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Medical Dictionary - Dictionary of Medicine and Human Biology

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a
  • abbr: absolute.
  • abbr: absorbency; absorbent.
  • abbr: acetum.
  • abbr: acid; acidity.
  • abbr: actin.
  • abbr: allergist; allergy.
  • abbr: alpha.
  • abbr: anode.
  • abbr: anterior.
  • abbr: artery.
  • abbr: asymmetric; asymmetry.
α, upper case A
  • Alpha, the first letter of the Greek alphabet
  • a classifier in the nomenclature of many sciences
  • Bunsen solubility coefficient
  • the first in a series
  • a position immediately adjacent to a carboxyl group
  • the first of a series of closely related compounds
  • an aromatic substituent on an aliphatic chain
  • the direction of a chemical bond away from the viewer
  • alpha particle
  • angle of optic rotation
  • degree of dissociation
[α]
Symbol for specific optic rotation.

α1PI
Abbreviation for human α1-protease inhibitor.

A
  • One of the four ABO blood groups characterized by the presence of antigens designated by the letter A and by the presence of antibodies against the antigens present in the B blood group
  • Ampere
  • adenine
  • alanine
  • alveolar gas
  • absorbance
  • adenosine or adenylic acid in polynucleotides
  • alanine or alanyl in polypeptides
  • first substrate in a multisubstrate enzyme-catalyzed reaction
  • Helmholtz energy
Å
Symbol for angstrom.

°A
Symbol for degree absolute; replaced by K (kelvin).

A−
Symbol for anion.

a
  • ante
  • area
  • asymmetric
  • auris
  • artery
  • arteria
  • atto-
  • systemic arterial blood
  • absorption coefficient
  • absorptivity
  • total acidity
a-, an-
Not, without, -less; equivalent to L. in- and E. un-. [G. not, un-, usually an- before a vowel]

AA, aa
Abbreviation for amino acid; aminoacyl.

aa
Abbreviation for arteries [TA], arteriae [TA].

aa.
Abbreviation for G. ana, of each; used in prescription writing following the name of two or more ingredients.

AAA
Abbreviation for abdominal aortic aneurysm; commonly, procedure for surgical correction of an A..

Aad
Abbreviation for α-aminoadipic acid.

AAF
Abbreviation for 2-acetylaminofluorene; 2-acetamidofluorene.

Aagenaes
O., Norwegian physician. See A. syndrome.

AAMC
Abbreviation for Association of American Medical Colleges.

AAR
Abbreviation for antigen-antibody reaction.

Aaron
Charles D., U.S. physician, 1866–1951. See A. sign.

Aarskog
Dagfinn J., Norwegian pediatrician, *1928. See A.-Scott syndrome.

AASH
Abbreviation for adrenal androgen-stimulating hormone.

AAV
Abbreviation for adeno-associated virus.

ab
Abdominal, e.g. exercising the abs.

Ab
Abbreviation for antibody.

ab
Abbr: abort; abortion

ab-, abs-
1. From, away from, off. 2. Prefix applied to electrical units in the CGS-electromagnetic system to distinguish them from units in the CGS-electrostatic system (prefix stat-) and those in the metric system or SI (no prefix). [L. ab, from, usually abs- before c, q, and t; often a- before m, p, or v]

AB
The one of the four ABO blood groups characterized by the presence of antigens designated by the letters A and B and by the absence of antibodies against these antigens.

Abadie
Joseph Louis Irénée Jean, French neurosurgeon, 1873–1946. See A. sign of tabes dorsalis.

abampere (ab-am′per)
Electromagnetic unit of current equal to 10 absolute amperes; a current that exerts a force of 2π dynes on a unit magnetic pole at the center of a circle of wire 1 cm in radius.

A band
One of the cross striations in striated muscle that contain myosin filaments and appear dark under the light microscope and light in polarized light.

abapical (a-bap′i-kal)
Opposite the apex.

abarognosis (a-bar′og-no′sis)
Loss of ability to appreciate the weight of objects held in the hand, or to differentiate objects of different weights. When the primary senses are intact, caused by a lesion of the contralateral parietal lobe. [G. a- priv. + baros, weight, + gnosis, knowledge]

abasia (a-ba′ze-a)
Inability to walk. See gait. [G. a- priv. + basis, step] atactic a., ataxic a. difficulty in walking due to ataxia of the legs.

abasia-astasia
See astasia-abasia.

abasic (a-ba′sik)
1. Affected by, or associated with, abasia. 2. Refers to loss of pyrimidine sites in DNA. SYN: abatic.

abatement (a-bat′ment)
1. A diminution or easing. 2. Reduction, ultimately elimination, of public health nuisances such as smoke, loud noise. [abate, fr. M.E. abaten, fr. O.Fr. abattre, to beat down, fr. L. L. batto, to beat, + -ment] sound a. generic term for any measures to reduce environmental noise.

abatic (a-bat′ik)
SYN: abasic.

abaxial, abaxile (ab-ak′se-al, -ak′sil)
1. Lying outside the axis of any body or part. 2. Situated at the opposite extremity of the axis of a part.

Abbe
Robert W., American surgeon, 1851–1928. Abbe is known for his pioneer work in the use of radium to treat cancer, for the use of X-rays to detect kidney stones, and for the use of catgut rings to support the intestines during operations for intestinal anastomosis. One of the foremost surgeons of his day, he specialized in plastic surgery for a time. See also A. flap.

Abbé
Ernst K., German physicist, 1840–1905. See Abbé condenser.

Abbe-Estlander operation
The grafting of a flap of tissue from one lip of the oral cavity to the other lip to correct a defect using a pedicle with an arterial supply.

Abbott
Alexander C., U.S. bacteriologist, 1860–1935. See A. stain for spores.

Abbott
W. Osler, U.S. physician, 1902–1943. See A. tube, Miller-A. tube.

Abbott artery
See under artery.

abciximab
Monoclonal antibody with antithrombotic properties used for the prevention and treatment of arterial occlusive disorders.

abcoulomb (ab-koo-lom′)
A unit of electrical charge equal to 10 coulombs. The charge that passes over a given surface in 1 sec if a current of 1 abampere is flowing across the surface. [ab + coulomb]

abdomen (ab-do′men, ab′do-men) [TA]
The part of the trunk that lies between the thorax and the pelvis. The a. does not include the vertebral region posteriorly but is considered by some anatomists to include the pelvis (abdominopelvic cavity). It includes the greater part of the abdominal cavity (cavitas abdominis [TA]), and is divided by arbitrary planes into nine regions. SEE ALSO: abdominal regions, under region. SYN: venter (1) [TA] . [L. a., etym. uncertain] acute a. any serious acute intra-abdominal condition (such as appendicitis) attended by pain, tenderness, and muscular rigidity, and for which emergency surgery must be considered. SYN: surgical a.. carinate a. a sloping of the sides with prominence of the central line of the a.. navicular a. SYN: scaphoid a.. a. obstipum rarely used term for deformity of the a. due to congenitally short rectus muscles. pendulous a. an a. with greatly relaxed muscular walls that sag down over the pubic region. protuberant a. unusual or prominent convexity of the a., due to excessive subcutaneous fat, poor muscle tone, or an increase in intraabdominal content. scaphoid a. a condition in which the anterior abdominal wall is sunken and presents a concave rather than a convex contour. SYN: navicular a.. surgical a. SYN: acute a..

abdominal (ab-dom′i-nal)
Relating to the abdomen.

abdomino-, abdomin-
The abdomen, abdominal. [L. abdomen, abdominis]

abdominocentesis (ab-dom′i-no-sen-te′sis)
Paracentesis of the abdomen. [abdomino- + G. kentesis, puncture]

abdominocyesis (ab-dom′i-no-si-e′sis)
1. SYN: abdominal pregnancy. 2. SYN: secondary abdominal pregnancy. [abdomino- + G. kyesis, pregnancy]

abdominocystic (ab-dom-i-no-sis′tik)
SYN: abdominovesical. [abdomino- + G. kystis, bladder]

abdominogenital (ab-dom′i-no-gen′i-tal)
Relating to the abdomen and the genital organs.

abdominohysterectomy (ab-dom′i-no-his-ter-ek′to-me)
SYN: abdominal hysterectomy.

abdominohysterotomy (ab-dom′i-no-his-ter-ot′o-me)
SYN: abdominal hysterotomy.

abdominopelvic (ab-dom′i-no-pel′vik)
Relating to the abdomen and pelvis, especially the combined abdominal and pelvic cavities.

abdominoperineal (ab-dom′i-no-par-i-ne′al)
Relating to both abdomen and perineum, as in a. resection of the rectum.

abdominoplasty (ab-dom′i-no-plas-te)
An operation performed on the abdominal wall for cosmetic purposes. [abdomino- + G. plastos, formed]

abdominoscopy (ab-dom-i-nos′ko-pe)
SYN: laparoscopy. [abdomino- + G. skopeo, to examine]

abdominoscrotal (ab-dom′i-no-skro′tal)
Relating to the abdomen and the scrotum.

abdominothoracic (ab-dom′i-no-tho-ras′ik)
Relating to both abdomen and thorax.

abdominovaginal (ab-dom′i-no-vag′i-nal)
Relating to both abdomen and vagina.

abdominovesical (ab-dom′i-no-ves′i-kal)
Relating to the abdomen and urinary bladder, or to the abdomen and gallbladder. SYN: abdominocystic.

abduce (ab-doos′)
SYN: abduct.

abducens (ab-doo′senz)
SYN: abducent. [L.] a. oculi SYN: lateral rectus (muscle).

abducent (ab-doo′sent)
1. Abducting; drawing away, especially away from the median plane. 2. SYN: a. nerve [CN VI]. SYN: abducens. [L. abducens]

abduct (ab-dukt′)
To move away from the median plane. SYN: abduce.

abduction (ab-duk′shun)
1. Movement of a body part away from the median plane (of the body, in the case of limbs; of the hand or foot, in the case of digits). 2. Monocular rotation (duction) of the eye toward the temple. 3. A position resulting from such movement. Cf.:adduction. [L. abductio]

abductor (ab-duk′ter, -tor)
SYN: a. (muscle).

Abegg
Richard, Danish chemist, 1869–1910. See A. rule.

Abell-Kendall method
See under method.

Abelson
Herbert T., U.S. pediatrician, *1941. See A. murine leukemia virus.

abembryonic (ab′em-bre-on′ik)
The area of the blastocyst opposite the region where the embryo is formed. [L. ab, from, + embryonic]

abenteric (ab-en-ter′ik)
A rarely used term meaning away from the intestine, said of a morbid process occurring elsewhere that would normally occur in the intestine. [L. ab, from, + G. enteron, intestine]

Abernethy
John, British surgeon and anatomist, 1764–1831. See A. fascia.

aberrant (ab-er′ant)
1. Differing from the normal; in botany or zoology, said of certain atypical individuals in a species. 2. Wandering off; said of certain ducts, vessels, or nerves deviating from the normal course or pattern. 3. SYN: ectopic (1) . [L. aberrans]

aberration (ab-er-a′shun)
1. Deviating from the normal course or pattern. 2. Deviant development or growth. SEE ALSO: chromosome. [L. aberratio] chromatic a. the difference in focus or magnification of an image arising because of a difference in the refraction of different wavelengths composing white light. SYN: chromatism (2) , color a., newtonian a.. chromosome a. any deviation from the normal number or morphology of chromosomes; also the phenotypic consequences thereof. color a. SYN: chromatic a.. coma a. 1. the distortion of image formation created when a bundle of light rays enters an optical system not parallel to the optic axis. 2. in botany, any tuft, as the hairs on a seed, or the greenery on a radish or a pineapple. SYN: coma (3) . [G. kome, hair, foliage] curvature a. lack of spatial correspondence causing the image of a straight extended object to appear curved. dioptric a. SYN: spherical a.. distortion a. the faulty formation of an image arising because the magnification of the peripheral part of an object is different from that of the central part when viewed through a lens. SEE ALSO: Petzval surface. lateral a. in spherical a., the distance between paraxial focus of central rays on the optic axis. longitudinal a. in spherical a., the distance separating the focus of paraxial and peripheral rays on the optic axis. mental a. disturbed thought or behavior that connotes a psychological or psychiatric impairment. See delusion. meridional a. an a. produced in the plane of a single meridian of a lens. monochromatic a. a defect in an optical image arising because of the nature of lenses; the main types are spherical, coma, curvature, and distortion a., and astigmatism of oblique pencils. newtonian a. SYN: chromatic a.. optical a. failure of rays from a point source to form a perfect image after traversing an optical system. spherical a. a monochromatic a. occurring in refraction at a spherical surface in which the paraxial and peripheral rays focus along the axis at different points. SYN: dioptric a.. ventricular a. SYN: aberrant ventricular conduction.

aberrometer (ab-er-rom′e-ter)
An instrument for measuring optical aberration or any error in experimentation. [L. aberratio, aberration, + G. metron, measure]

abetalipoproteinemia (a-ba′ta-lip′o-pro′ten-e′me-a) [MIM*200100]
A disorder characterized by an absence of low-density beta-lipoprotein, presence of acanthocytes in blood, retinal pigmentary degeneration, malabsorption, engorgement of upper intestinal absorptive cells with dietary triglycerides, and neuromuscular abnormalities; autosomal recessive inheritance, caused by mutation in the gene encoding microsomal triglyceride transfer protein (MTP) on chromosome 4q. SYN: Bassen-Kornzweig syndrome. [G. a-, priv., + β, + lipoprotein + -emia, blood] normotriglyceridemic a. a. with normal levels of triglycerides. This inherited disorder (possibly autosomal recessive) is probably due to the absence of apolipoprotein B-100.

abeyance (a-ba′ans)
A state of temporary abolition of function. [fr. O. Fr.]

abfarad (ab-far′ad)
Electromagnetic unit of capacity equal to 109 farads.

ABG
Abbreviation for arterial blood gas. See blood gases, under gas.

abhenry (ab-hen′re)
Electromagnetic unit of inductance equal to 10−9 henry.

ability (a-bil′i-te)
The physical, mental, or legal competence to function. [L. habilitas, aptitude]

abiotic (a-bi-ot′ik)
1. Incompatible with life. 2. Without life.

abiotrophy (ab-e-ot′ro-fe)
An age-dependent manifestation of a genetically determined trait. [G. a- priv. + bios, life, + trophe, nourishment]

abirritation (ab-ir-i-ta′shun)
Obsolete term for diminution or abolition of irritability in a part. [L. ab, from, + irrito, pp. -atus, to irritate]

abl
An oncogene found in the Abelson strain of mouse leukemia virus and involved in the Philadelphia chromosome translocation in chronic granulocytic leukemia.

ablastemic (a-blas-tem′ik)
Not germinal or blastemic. [G. a- priv. + blastema, sprout]

ablastin (a-blas′tin)
An antibody that seems to inhibit reproduction of trypanosomes; found in rats infected with Trypanosoma lewisi. [G. a- priv. + blastos, germ]

ablate (ab-lat′)
To remove, or to destroy the function of. [L. au- fero, pp. ab- latus, to take away]

ablation (ab-la′shun)
Removal of a body part or the destruction of its function, as by a surgical procedure, morbid process, or noxious substance. [L. see ablate] electrode catheter a. a method of ablating the site of origin of arrhythmias whereby high-energy electrical current is delivered by intravascular catheters. endometrial a. therapeutic selective endometrial destruction. laparoscopic uterosacral nerve a. laparoscopic transection via laser (usually KTP or argon) of the uterosacral nerves for the treatment of primary dysmenorrhea.

ablepharia (a-blef-ar′e-a)
Congenital absence of the eyelids. SEE ALSO: cryptophthalmus, microblepharon. [G. a- priv. + blepharon, eyelid]

abluent (ab′loo-ent)
1. Cleansing. 2. Anything with cleansing properties. [L. abluens, fr. ab-luo, to wash off]

ablution (ab-loo′shun)
An act of washing or bathing. [L. ablutio, washing off, cleansing]

abnerval (ab-ner′val)
Away from a nerve; denoting specifically a current of electricity passing through a muscular fiber in a direction away from the point of entrance of the nerve fiber. SYN: abneural (1) .

abneural (ab-noor′al)
1. SYN: abnerval. 2. Away from the neural axis. [L. ab, away from, + G. neuron, nerve]

abnormal (ab-nor′mal)
Not normal; differing in any way from the usual state, structure, condition, or rule.

abnormality (ab-nor-mal′i-te)
1. The state or quality of being abnormal. 2. An anomaly, deformity, malformation, impairment, or dysfunction. figure-of-8 a. a radiographic appearance associated with total anomalous drainage of the pulmonary venous circulation into enlarged right and anomalous left superior venae cavae, that produces a globular density above the heart; the silhouette suggests the figure 8; e.g., TAPVR. SEE ALSO: anomalous pulmonary venous connections, total or partial, under connection. SYN: snowman a.. neuronal migration a. SYN: cortical dysplasia. snowman a. SYN: figure-of-8 a..

ABO blood group
See Blood Groups appendix.

abohm (ab′om)
Electromagnetic unit of resistance equal to 10−9 ohm.

aborad, aboral (ab-o′rad, -ral)
In a direction away from the mouth; opposite of orad. [L. ab, from, + os (or-), mouth]

abort (a-bort′)
1. To give birth to an embryo or fetus before it is viable. SEE ALSO: miscarry. 2. To remove products of conception prematurely to destroy the offspring. 3. To arrest a disease in its earliest stages. [L. aborior, to fail at onset]

aborticide (ah-bor′ti-sid)
SYN: abortifacient (1) . [L. flabboriri, to miscarry + cadere, to kill.]

abortient (a-bor′shent)
SYN: abortifacient (1) .

abortifacient (a-bor-ti-fa′shent)
1. Producing abortion. SYN: aborticide, abortient, abortigenic, abortive (3) . 2. An agent that produces abortion. [L. abortus, abortion, + facio, to make]

abortigenic (a-bor-ti-jen′ik)
SYN: abortifacient (1) . [L. abortus, abortion, + genesis, production]

abortion (a-bor′shun)
1. Expulsion from the uterus of an embryo or fetus prior to the stage of viability (20 weeks' gestation or fetal weight <500 g). A distinction made between a. and premature birth: premature infants are those born after the stage of viability but prior to 37 weeks. A. may be either spontaneous (occurring from natural causes) or induced (artificial or therapeutic). 2. The arrest of any action or process before its normal completion. ampullar a. a. resulting from pregnancy in the ampulla of the fallopian tube. complete a. 1. the complete expulsion or extraction from its mother of a fetus or embryo; 2. complete expulsion of any other product of gestation. ( e.g., blighted ovum). criminal a. termination of pregnancy in violation of law. SYN: illegal a.. elective a. an a. without medical justification but done in a legal way, as in the United States. habitual a. SYN: recurrent a.. illegal a. SYN: criminal a.. incomplete a. a. in which part of the products of conception have been passed but part (usually the placenta) remains in the uterus. induced a. a. brought on purposely by drugs or mechanical means. inevitable a. a. characterized by rupture of the membranes or the cervical dilation in a previable pregnancy in the presence of vaginal bleeding and uterine contractions. infected a. a septic complication of an a.. menstrual extraction a. a technique for aspiration of early products of conception from the uterus a few days after the first missed menstrual period. missed a. a. in which the fetus dies in utero but the product of conception is retained in utero for two months or longer. recurrent a. the loss of 3 or more sequential pregnancies before 20 weeks of gestation. SYN: habitual a.. septic a. an infectious a. complicated by fever, endometritis, and parametritis. spontaneous a. a. that has not been artificially induced. SYN: miscarriage. therapeutic a. a. induced because of the mother's physical or mental health, or to prevent birth of a deformed child or a child resulting from rape. threatened a. cramplike pains and slight show of blood that may or may not be followed by the expulsion of the fetus during the first 20 weeks of pregnancy. tubal a. rupture of an oviduct, the seat of ectopic pregnancy, or extrusion of the product of conception through the fimbriated end of the oviduct; aborted ectopic pregnancy, the pregnancy having originated in a fallopian tube. SYN: aborted ectopic pregnancy.

abortionist (a-bor′shun-ist)
One who interrupts a pregnancy.

abortive (a-bor′tiv)
1. Not reaching completion; e.g., said of an attack of a disease subsiding before it has fully developed or completed its course. 2. SYN: rudimentary. 3. SYN: abortifacient (1) . [L. abortivus]

abortus (a-bor′tus)
Any product (or all products) of an abortion. [L.]

aboulia (a-boo′le-a)
SYN: abulia.

ABP
Abbreviation for androgen binding protein.

ABPA
Abbreviation for allergic bronchopulmonary aspergillosis.

ABR
Abbreviation for auditory brainstem response. See auditory brainstem response.

abrachia (a-bra′ke-a)
Congenital absence of arms. See amelia. [G. a- priv. + brachion, arm]

abrachiocephaly, abrachiocephalia (a-bra′ke-o-sef′a-le, -se-fa′le-a)
Congenital absence of arms and head. SYN: acephalobrachia. [G. a- priv. + brachion, arm, + kephale, head]

abrade (a-brad′)
1. To wear away by mechanical action. 2. To scrape away part or all of the surface layer from a part. [L. ab-rado, pp. -rasus, to scrape off]

Abrahams
Robert, U.S. physician, 1861–1935. See A. sign.

Abrams
Albert, U.S. physician, 1863–1924. See A. heart reflex.

abrasion (a-bra′zhun)
1. An excoriation, or circumscribed removal of the superficial layers of skin or mucous membrane. SYN: abraded wound. 2. A scraping away of a portion of the surface. 3. In dentistry, the pathological grinding or wearing away of tooth substance by incorrect tooth-brushing methods, foreign objects, bruxism, or similar causes. SYN: grinding. Cf.:attrition. [see abrade] brush burn a. brush burn. gingival a. a lesion of the gingiva resulting from mechanical removal of a portion of the surface epithelium. tooth a. loss or wearing away of tooth structure caused by the abrasive characteristics of substances other than foods.

abrasive (a-bra′siv)
1. Causing abrasion. 2. Any material used to produce abrasions. 3. A substance used in dentistry for abrading, grinding, or polishing.

abrasiveness (a-bra′siv-nes)
1. That property of a substance that causes surface wear by friction. 2. The quality of being able to scratch or wear away another material.

abreact (ab-re-akt′)
1. To show strong emotion while reliving a previous traumatic experience. 2. To discharge or release repressed emotion.

abreaction (ab-re-ak′shun)
In freudian psychoanalysis, an episode of emotional release or catharsis associated with the bringing into conscious recollection previously repressed unpleasant experiences. motor a. the release of an unconscious thought, idea, or impulse through motor or muscular expression.

abrin (ab′rin)
A phytotoxin from jequirity seeds or Indian liquorice, the red seeds (Abrus precatorius); used in ophthalmology.

abruption (ab-rup′shun)
A tearing away, separation, or detachment.

abruptio placentae (ab-rup′she-o pla-sen′te)
Premature detachment of a normally situated placenta.

Abrus (a′brus)
A genus of leguminous plants. The root of A. precatorius, Indian liquorice, is sometimes used as a substitute for liquorice; the seeds are toxic and may cause vomiting, diarrhea, convulsions, and death if chewed. [more correctly Habrus, from G. habros, graceful]

abscess (ab′ses)
A localized collection of pus, often associated with swelling and other signs of inflammation.
A cavity formed by liquefactive necrosis within solid tissue. [L. abscessus, a going away]

  • acute abscess: a recently formed abscess with little or no fibrosis in the wall of the cavity, aka hot abscess.
  • alveolar abscess: an abscess situated within the alveolar process of the jaws, most often caused by extension of infection from an adjacent nonvital tooth, aka dental abscess, dentoalveolar abscess, root abscess.
  • amebic abscess: an area of liquefaction necrosis of the liver or other organ containing amebae, often following amebic dysentery, aka tropical abscess.
  • apical abscess: periapical abscess.
  • apical periodontal abscess: periapical abscess.
  • appendiceal abscess: an intraperitoneal abscess, usually in the right iliac fossa, resulting from extension of infection in acute appendicitis, especially with perforation of the appendix, aka periappendiceal abscess.
  • Bartholin abscess: an abscess of the vulvovaginal gland.
  • Bezold abscess: an abscess deep to the superior part of the sternocleidomastoid muscle due to suppurative destruction of the mastoid tip cells in mastoiditis.
  • bicameral abscess: an abscess with two separate cavities or chambers.
  • bone abscess: suppuration within the medullary cavity (osteomyelitis), cortex, or periosteum of bone.
  • Brodie abscess: a chronic abscess of bone surrounded by dense fibrous tissue and sclerotic bone.
  • bursal abscess: suppuration within a bursa.
  • caseous abscess: an abscess containing white solid or semisolid material of cheeselike consistency; usually tuberculous. SEE ALSO: cheesy abscess.
  • cheesy abscess: an abscess that contains necrotic tissue with a cheeselike consistency; typically seen in tuberculosis. SEE ALSO: caseous abscess.
  • cholangitic abscess: (ko-lan-ji′-tik) a focal area of pus formation in the liver resulting from infection arising in the biliary tract.
  • chronic abscess: a long-standing collection of pus surrounded by fibrous tissue.
  • cold abscess: an abscess without heat or other usual signs of inflammation;
  • crypt abscesses: abscesses in crypts of Lieberkühn of the large intestinal mucosa; a characteristic feature of ulcerative colitis.
  • dental abscess, dentoalveolar abscess: alveolar abscess.
  • diffuse abscess: a collection of pus not circumscribed by a well-defined capsule.
  • Douglas abscess: suppuration in Douglas pouch.
  • dry abscess: the remains of an abscess after the pus is absorbed.
  • Dubois abscesses: small cysts of the thymus containing polymorphonuclear leukocytes but lined by squamous epithelium; reported in congenital syphilis but also found in the absence of syphilis, aka Dubois disease, thymic abscesses.
  • embolic abscess: an abscess arising distal to the point of arrest of a septic embolus.
  • fecal abscess: stercoral abscess.
  • follicular abscess: an abscess in a hair, tonsillar, or other follicle.
  • gas abscess: an abscess containing gas. Frequently caused by gas-forming organisms such as Enterobacter aerogenes or Escherichia coli.
  • gingival abscess: an abscess confined to the gingival soft tissue, aka gumboil, parulis.
  • gravitation abscess: perforating abscess.
  • gummatous abscess: an abscess due to the softening and breaking down of a gumma, especially in bone.
  • hematogenous abscess: an abscess caused by blood-borne organisms.
  • hot abscess: acute abscess.
  • hypostatic abscess: perforating abscess.
  • ischiorectal abscess: an abscess involving the ischiorectal fossa.
  • lateral alveolar abscess: an alveolar abscess located along the lateral root surface of a tooth, aka pericemental abscess.
  • lateral periodontal abscess: an abscess that forms at the depth of a periodontal pocket due to multiplication of pyogenic microorganisms or the presence of foreign material.
  • mastoid abscess: an abscess due to coalescence of the mastoid air cells in mastoiditis.
  • metastatic abscess: a secondary abscess formed, at a distance from the primary focus, as a result of the transportation of pyogenic bacteria by the lymph or bloodstream.
  • migrating abscess: perforating abscess.
  • miliary abscess: one of a number of minute collections of pus, widely disseminated throughout an area or the whole body.
  • Munro abscess: Munro microabscess.
  • orbital abscess: a collection of pus between the orbital periosteum and the lamina papyracea; frequently an extension of purulent infection of the paranasal sinuses, usually the ethmoids.
  • otitic abscess: a brain abscess, usually involving the temporal lobe or cerebellar hemisphere, secondary to suppuration of the middle ear.
  • palatal abscess:1. a lateral periodontal abscess associated with the lingual surface of a maxillary tooth; 2. an alveolar abscess that has eroded the cortical plate, allowing extension into the palatal soft tissues.
  • pancreatic abscess: an abscess in the pancreatic or peripancreatic area usually related to pancreatitis.
  • parafrenal abscess: an abscess that occurs on either side of the frenum of the penis.
  • parametric abscess, parametritic abscess: an abscess in the connective tissue of the broad ligament of the uterus.
  • paranephric abscess: an abscess in the region of the kidney, outside the renal fascia.
  • parapharyngeal abscess: an abscess lying lateral to the pharynx.
  • parotid abscess: suppuration in the parotid gland; an often rapidly progressing complication of parotitis.
  • Pautrier abscess: Pautrier microabscess.
  • pelvic abscess: an abscess in the pelvic peritoneal cavity, developing as a complication of diffuse peritonitis or of localized peritonitis associated with abdominal or pelvic inflammatory disease, such as salpingitis; the pus frequently collects in the rectovesical or rectouterine pouch.
  • perforating abscess: an abscess that breaks down tissue barriers to enter adjacent areas, aka gravitation abscess, hypostatic abscess, migrating abscess, wandering abscess.
  • periapical abscess: an alveolar abscess localized around the apex of a tooth root, aka apical abscess, apical periodontal abscess.
  • periappendiceal abscess: appendiceal abscess.
  • periarticular abscess: an abscess surrounding a joint, but not necessarily involving it.
  • pericemental abscess: lateral alveolar abscess.
  • pericoronal abscess: an abscess developing in the inflamed dental follicular tissue overlying the crown of a partially erupted tooth.
  • perinephric abscess: an abscess within Gerota fascia but outside the renal capsule.
  • periodontal abscess: an alveolar abscess or a lateral periodontal abscess.
  • perirectal abscess: an abscess in connective tissue adjacent to the rectum or anus.
  • peritonsillar abscess: extension of tonsillar infection beyond the tonsillar capsule with abscess formation between the capsule and the musculature of the tonsillar fossa.
  • periureteral abscess: an abscess surrounding the ureter.
  • periurethral abscess: an abscess involving the tissues around the urethra, particularly the corpus spongiosum.
  • phlegmonous abscess: circumscribed suppuration characterized by intense surrounding inflammatory reaction that produces induration and thickening of the affected area.
  • Pott abscess: tuberculous abscess of the spine.
  • premammary abscess: an abscess in the subcutaneous tissue covering the mammary gland.
  • psoas abscess: an abscess, usually tuberculous, originating in tuberculous spondylitis and extending through the iliopsoas muscle to the inguinal region.
  • pulp abscess: an abscess involving the soft tissue within the pulp chamber of a tooth, usually a sequela of caries or less frequently of trauma.
  • pyemic abscess: a hematogenous abscess resulting from pyemia, septicemia, or bacteremia, aka septicemic abscess.
  • radicular abscess: alveolar abscess, an abscess around a tooth root.
  • residual abscess: an abscess recurring at the site of a former abscess resulting from persistence of microbes and pus.
  • retrobulbar abscess: an abscess posterior to the globe of the eye.
  • retrocecal abscess: an abscess located posterior to the cecum, usually resulting from perforation of a retrocecal appendix.
  • retropharyngeal abscess: an abscess arising, usually, in retropharyngeal lymph nodes, most commonly in infants.
  • ring abscess: an acute purulent inflammation of the corneal periphery in which a necrotic area is surrounded by an annular girdle of leukocytic infiltration.
  • root abscess: alveolar abscess.
  • satellite abscess: an abscess closely associated with a primary abscess.
  • septicemic abscess: pyemic abscess.
  • stellate abscess: a star-shaped necrotic area surrounded by histiocytes, seen within swollen lymph nodes in lymphogranuloma venereum and cat scratch fever.
  • stercoral abscess: a collection of pus and feces, aka fecal abscess.
  • sterile abscess: 1. an abscess whose contents are not caused by pyogenic bacteria. 2. an abscess that when aspirated or cultured does not grow bacteria.
  • stitch abscess: suture abscess.
  • subdiaphragmatic abscess: subphrenic abscess.
  • subepidermal abscess: a microscopic abscess located in the dermis just beneath the epidermis.
  • subhepatic abscess: an abscess located immediately beneath the liver.
  • subperiosteal abscess: an abscess between the periosteum and cortical plate of the bone.
  • subphrenic abscess: an abscess directly beneath the diaphragm, aka subdiaphragmatic abscess.
  • subungual abscess: suppuration extending beneath a fingernail or toenail, usually from a paronychia.
  • sudoriferous abscess: a collection of pus in a sweat gland.
  • suture abscess: a purulent exudate surrounding a stitch, particularly a corneal stitch, aka stitch abscess.
  • thymic abscesses: Dubois abscesses.
  • Tornwaldt abscess: chronic infection of the pharyngeal bursa. SEE ALSO: Tornwaldt syndrome.
  • tropical abscess: amebic abscess.
  • tuboovarian abscess: a large abscess involving a uterine tube and an adherent ovary, resulting from extension of purulent inflammation of the tube.
  • verminous abscess: worm abscess.
  • wandering abscess: perforating abscess.
  • worm abscess: abscess due to parasitic worms or in which worms are found, aka verminous abscess.
abscissa (ab-sis′a)
In a plane cartesian coordinate system, the horizontal axis (x). Cf.:ordinate. [L. ab-scindo, pp. -scissus, to cut away from]

abscission (ab-si′shun)
Cutting away. [L. ab-scindo, pp. -scissus, to cut away from]

absconsio (ab-skon′she-o)
A recess, cavity, or depression; used especially in osteology to denote a bony cavity which accommodates the head of another bone. [Mod. L. fr. abs-condo, pp. -conditus or -consus, to hide]

abscopal (ab-sko′pal, -skop′al)
Denoting the effect that irradiation of a tissue has on remote nonirradiated tissue. [ab- + G. skopos, target, + -al]

absence (ab′sens)
Paroxysmal attacks of impaired consciousness, occasionally accompanied by spasm or twitching of cephalic muscles, which usually can be brought on by hyperventilation; depending on the type and severity of the a., the EEG may show an abrupt onset of a 3-sec spike and wave pattern as in simple a., or in atypical cases, a 4-sec spike and wave or faster spike complexes. The clinical states accompanying these EEG abnormalities may be classified as: 1) a. with no overt manifestations, e.g., simple a.; epileptic a.; subclinical a.; 2) a. with clonic movements, e.g., myoclonic a.; 3) a. with atonic states, e.g., atonic a.; 4) a. with tonic contractions, e.g., hypertonic muscular contraction; 5) a. with automatisms, e.g., various stereotyped movements, usually of the face or hands; 6) a. with atypical features, e.g., bizarre motor activity. [L. absentia] pure a. SYN: simple a.. simple a. a brief clouding of consciousness accompanied by the abrupt onset of 3-sec spikes and waves on EEG. SYN: pure a..

abs. feb.
Abbreviation for L. absente febre, when fever is absent.

Absidia (ab-sid′e-a)
A genus of fungi (family Mucoraceae) commonly found in nature. Thermophilic species survive in compost piles at temperatures exceeding 45°C and may cause mucormycosis (zygomycosis) in humans.

absinthe (ab′sinth)
A liqueur consisting of an alcoholic extract of absinthium and other bitter herbs.

absinthin (ab′sin-thin)
A bitter principle, C30H40O8, obtained from absinthium.

absinthium (ab-sin′the-um)
The dried leaves and tops of Artemisia a. (family Compositae). The infusion is now seldom used, but it has been used as a tonic; in large or frequently repeated doses it produces headache, trembling, and epileptiform convulsions. SYN: wormwood. [L., fr. G. apsinthion]

absinthol (ab-sin′thawl)
SYN: thujone.

absolute (ab′so-loot)
Unconditional; unlimited; uncombined; undiluted (as in case of alcohol); certain. [L. absolutus, complete, pp. of ab-solvo, to loosen from]

absorb (ab-sorb′)
1. To take in by absorption. 2. To reduce the intensity of transmitted light. [L. ab-sorbeo, pp. -sorptus, to suck in]

absorbance (A, A) (ab-sor′bans)
In spectrophotometry, log of the ratio of the radiant power of the incident radiation to the radiant power of the transmitted radiation. SYN: absorbancy, absorbency, extinction (2) , optic density. specific a. a. per unit of concentration. See specific absorption coefficient.

absorbancy (ab-sor′ban-se)
SYN: absorbance.

absorbefacient (ab-sor-be-fa′shunt)
1. Causing absorption. 2. Any substance possessing such quality. [L. ab-sorbeo, to suck in, + facio, to make]

absorbency (ab-sor′ben-se)
SYN: absorbance.

absorbent (ab-sor′bent)
1. Having the power to absorb, soak up, or take into itself a gas, liquid, light rays, or heat. SYN: absorptive, bibulous. 2. Any substance possessing such power. 3. Material (usually caustic) for removal of carbon dioxide from circuits in which rebreathing occurs; e.g., anesthesia and basal metabolism equipment.

absorber head (ab-sor′ber hed)
Portion of a rebreathing anesthesia circuit that contains carbon dioxide absorbent; often referred to as a canister.

absorption (ab-sorp′shun)
1. The taking in, incorporation, or reception of gases, liquids, light, or heat. Cf.:adsorption. 2. In radiology, the uptake of energy from radiation by the tissue or medium through which it passes. See half-value layer, photoelectric effect, attenuation. [L. absorptio, fr. absorbeo, to swallow] cutaneous a. SYN: percutaneous a.. disjunctive a. a. of living tissue in immediate relation with a necrosed part, producing a line of demarcation. electron resonance a. electron spin resonance. external a. the a. of substances through skin, mucocutaneous surfaces, or mucous membranes. interstitial a. the removal of water or of substances in the interstitial fluid by the lymphatics. parenteral a. a. by any route other than the alimentary tract. pathologic a. parenteral a. of any excremental or pathologic material into the bloodstream, e.g., pus, urine, bile, etc. percutaneous a. the a. of drugs, allergens, and other substances through unbroken skin. The corneal layer of epidermis is the principal barrier. SYN: cutaneous a.. photoelectric a. interaction of a gamma photon with matter in which the incident photon is completely absorbed, giving up all its energy by displacing and accelerating an inner shell electron. SEE ALSO: photoelectric effect.

absorptive (ab-sorp′tiv)
SYN: absorbent (1) .

absorptivity (a) (ab-sorp-tiv′i-te)
1. SYN: specific absorption coefficient. 2. SYN: molar absorption coefficient. 3. The ability of a material to absorb electromagnetic radiation. molar a. SYN: molar absorption coefficient.

abstinence (ab′sti-nens)
Refraining from the use of certain articles of diet, alcoholic beverages, illegal drugs, or from sexual intercourse. [L. abs-tineo, to hold back, fr. teneo, to hold]

abstract (ab′strakt)
1. A preparation made by evaporating a fluid extract to a powder and triturating with milk sugar. 2. A condensation or summary of a scientific or literary article or address. [L. ab-straho, pp. -tractus, to draw away] structured a. summary description of a published paper, in which information about the study reported in the paper is set out in a systematic, stylized form under headings such as aims, methods, main outcome measures, results, conclusions.

abstraction (ab-strak′shun)
1. Distillation or separation of the volatile constituents of a substance. 2. Exclusive mental concentration. 3. The making of an abstract from the crude drug. 4. Malocclusion in which the teeth or associated structures are lower than their normal occlusal plane. SEE ALSO: odontoptosis. 5. The process of selecting a certain aspect of a concept from the whole. [L. abs-traho, pp. -tractus, to draw away]

abstriction (ab-strik′shun)
In fungi, the formation of asexual spores by cutting off portions of the sporophore through the growth of dividing partitions. [L. ab-, from, + strictura, a contraction]

abterminal (ab-ter′mi-nal)
In a direction away from the end and toward the center; denoting the course of an electrical current in a muscle. [L. ab, from, + terminus, end]

abulia (a-boo′le-a)
1. Loss or impairment of the ability to perform voluntary actions or to make decisions. 2. Reduction in speech, movement, thought, and emotional reaction; a common result of bilateral frontal lobe disease. SYN: aboulia. [G. a- priv. + boule, will]

abulic (a-boo′lik)
Relating to, or suffering from, abulia.

abundance (a-bun′dans)
The average number of types of macromolecules ( e.g., mRNAs) per cell.

abuse (a-bus′)
1. Misuse, wrong use, especially excessive use, of anything. 2. Injurious, harmful, or offensive treatment, as in child a. or sexual a. child a. the psychological, emotional, and sexual a. of a child, typically by a parent, stepparent, or parent surrogate. See domestic violence. drug a. habitual use of drugs not needed for therapeutic purposes, such as solely to alter one's mood, affect, or state of consciousness, or to affect a body function unnecessarily (as in laxative a.); nontherapeutic use of drugs. elder a. the physical or emotional a., including financial exploitation, of an elderly person, by one or more of the individual's children, nursing home caregivers, or others. sexual a. See domestic violence. spouse a., spousal a. See domestic violence. substance a. maladaptive pattern of use of a drug, alcohol, or other chemical agent that may lead to social, occupational, psychological, or physical problems.

abutment (a-but′ment)
In dentistry, a natural tooth or implanted tooth substitute, used for the support or anchorage of a fixed or removable prosthesis. auxiliary a. a tooth other than the one supporting the direct retainer, assisting in the overall support of a removable partial denture. ball and socket a. an a. connected to a fixed partial denture by a ball and socket-shaped nonrigid connector. dovetail stress-broken a. an a. connected to a fixed partial denture by a nonrigid connector that is trapezoidal in cross-section. intermediate a. a natural tooth, or an implanted tooth substitute, without other natural teeth in proximal contact, used along with the mesial and distal abutments to support a prosthesis; often called a “pier.” isolated a. a lone-standing tooth, or root, used as an a. with edentulous areas mesial and distal to it. splinted a. the joining of two or more teeth into a rigid unit by means of fixed restorations to form a single a. with multiple roots.

ABVD
Abbreviation for a chemotherapy regimen of Adriamycin (doxorubicin), bleomycin, vinblastine, and dacarbazine; used to treat neoplastic diseases, such as Hodgkin lymphoma.

abvolt (ab′volt)
The CGS electromagnetic unit of difference of potential equal to 10−8 V. The potential difference between two points such that 1 erg of work will be done when 1 abcoulomb of charge moves from point to point.

abzyme (ab′zim)
SYN: catalytic antibody. [antibody + enzyme]

AC
Abbreviation for alternating current.

Ac
Symbol for actinium; acetyl.

aC
Symbol for arabinosylcytosine.

a.c.
Abbreviation for L. ante cibum, before a meal or ante cibos, before meals.

AC/A
Abbreviation for accommodative convergence-accommodation ratio.

acacia (a-ka′she-a)
The dried gummy exudation from A. senegal and other species of A. (family Leguminosae), prepared as a mucilage and syrup; used as an emollient, demulcent excipient, and suspending agent in pharmaceuticals and foods; formerly used as a transfusion fluid. SYN: gum arabic. [G. akakia]

acalculia (a′kal-ku′le-a)
A form of aphasia characterized by the inability to perform simple mathematical problems; found with lesions of various areas of the cerebral hemispheres, and often an early sign of dementia. [G. a- priv. + L. calculo, to reckon]

acampsia (a-kamp′se-a)
Rarely used term for stiffening or rigidity of a joint for any reason. [G. a- priv. + kampto, to bend]

acanth-
See acantho-.

acantha (a-kan′tha)
1. A spine or spinous process. 2. The spinous process of a vertebra. [G. akantha, a thorn]

acanthamebiasis (a-kan′tha-me-bi′a-sis)
Infection by free-living soil and water amebae of the genus Acanthamoeba that may result in a necrotizing dermal or tissue invasion, a fulminating and usually fatal primary amebic meningoencephalitis, or a subacute or chronic granulomatous amebic encephalitis.

Acanthamoeba (a-kan-tha-me′ba)
A genus of free-living ameba (family Acanthamoebidae, order Amoebida) found in and characterized by the presence of acanthopodia. Human infection includes invasion of skin or colonization following injury, corneal invasion and colonization, and possibly lung or genitourinary tract colonization; a few cases of brain or CNS invasion have occurred, but not solely by the olfactory epithelium route of entry as with the more virulent infections caused by Naegleria fowleri. Species responsible are chiefly A. culbertsoni, but cases have been reported involving A. castellanii, A. polyphaga, and A. astronyxis, though most cases have been chronic rather than fulminating and rapidly fatal as with Naegleria fowleri infection. [G. akantha, thorn, spine, + Mod. L. amoeba, fr. G. amoibe, change]

acanthella (a-kan-thel′a)
An intermediate larva stage of Acanthocephala, formed within the arthropod host; a preinfective, nonencysted stage leading to the infective cystacanth. [G. akantha, thorn, spine]

acanthesthesia (a-kan-thes-the′ze-a)
Paresthesia of a pinprick. [G. akantha, thorn, + aisthesis, sensation]

Acanthia lectularia (a-kan′the-a lek-tu-lar′e-a)
Early name for Cimex lectularius. [G. akantha, thorn, prickle; L. lectus, a bed]

acanthion (a-kan′the-on)
The tip of the anterior nasal spine. SYN: akanthion. [G. akantha, thorn]

acantho-
A spinous process; spiny, thorny. [G. akantha, a thorn, the backbone, the spine, fr. ake, a point, + anthos, a flower]

Acanthocephala (a-kan-tho-sef′a-la)
The thorny-headed worms, a phylum (formerly considered a class) of obligatory parasites without an alimentary canal, characterized by an anterior introvertible spiny proboscis. They superficially resemble nematodes but are cestode like in other traits, and hence are grouped as a distinctive phylum of helminths. In the adult stage they are parasites of vertebrate animals, mostly fish and amphibians; the larval stage is passed in invertebrates, chiefly crustaceans and insects. [acantho- + G. kephale, head]

acanthocephaliasis (a-kan′tho-sef-a-li′a-sis)
An illness caused by infection with a species of Acanthocephala.

Acanthocheilonema (a-kan′tho-ki-lo-ne′ma)
A genus of filarial worms parasitic in man, now considered part of the genus Mansonella. [acantho- + G. cheilos, lip, + nema, thread]

acanthocyte (a-kan′tho-sit)
An erythrocyte characterized by multiple spiny cytoplasmic projections, as in acanthocytosis. [acantho- + G. kytos, cell]

acanthocytosis (a-kan′tho-si-to′sis)
A rare condition in which the majority of erythrocytes are acanthocytes; a regular feature of abetalipoproteinemia; also sometimes present in severe hepatocellular disease. SYN: acanthrocytosis.

acanthoid (a-kan′thoyd)
Spine-shaped.

acantholysis (ak-an-thol′i-sis)
Separation of individual epidermal keratinocytes from their neighbor, as in conditions such as pemphigus vulgaris and Darier disease. [acantho- + G. lysis, loosening]

acanthoma (ak-an-tho′ma)
A tumor formed by proliferation of epithelial squamous cells. SEE ALSO: keratoacanthoma. [acantho- + G. -oma, tumor] clear cell a. a small sharply demarcated benign epidermal tumor of a leg or arm with acanthosis and accumulation of glycogen in keratinocytes having pale-staining cytoplasm.

acanthopodia (a-kan-tho-po′de-a)
Toothlike pseudopodia observed in some amebae, typically in members of the genus Acanthamoeba. [acantho- + G. pous, podos, foot]

acanthor (a-kan′thor)
The spindle-shaped embryo, with rostellar hooks and body spines, formed within the egg shell of Acanthocephala; this stage burrows into the body cavity of its first intermediate host, usually a crustacean in aquatic cycles, or insects in terrestrial cycles. [G. akantha, thorn or spine]

acanthosis (ak-an-tho′sis)
An increase in the thickness of the stratum spinosum of the epidermis. [acantho- + G. -osis, condition] glycogenic a. elevated gray-white plaques of distal esophageal or vaginal mucosa, with epithelium thickened by proliferation of large glycogen-filled squamous cells. a. nigricans an eruption of velvet warty benign growths and hyperpigmentation occurring in the skin of the axillae, neck, anogenital area, and groin; in adults, may be associated with internal malignancy, endocrine disorders, or obesity; a benign hereditary type occurs in children. SEE ALSO: pseudoacanthosis nigricans. [L. fr. niger, black]

acanthotic (ak-an-thot′ik)
Pertaining to or characteristic of acanthosis.

acanthrocyte (a-kan′thro-sit)
Obsolete term for acanthocyte.

acanthrocytosis (a-kan′thro-si-to′sis)
Obsolete term for acanthocytosis. SYN: acanthocytosis.

acapnia (a-kap′ne-a)
Absence of carbon dioxide in the blood; sometimes used erroneously for hypocapnia. [G. a- priv. + kapnos, smoke]

acarbose (a-kar′bos)
An oligosaccharide alpha-glucosidase inhibitor; adjunctive therapy in type 2 diabetes mellitus to blunt postprandial hyperglycemia.

acardia (a-kar′de-a)
Congenital absence of the heart; a condition sometimes occurring in one member of monozygotic twins or in one member of conjoined twins when pair partner monopolizes the placental blood supply; can also occur in triplet pregnancies. [G. a- priv. + kardia, heart]

acardiac (a-car′de-ak)
Without a heart.

acardius (a-kar′de-us)
A twin without a heart that remains viable by using the placental circulation of its mate. a. acephalus acephalocardius;an acardiac conceptus in which the head and thoracic organs are absent; ribs and vertebrae may be present, and upper limbs are either absent or defective. a. amorphus a shapeless product of conception covered by skin and hair. a. anceps an acardiac fetus with partly developed head and deformed face, trunk, and limbs.

acariasis (ak-ar-i′a-sis)
Any disease caused by mites, usually a skin infestation. See mange. psoroptic a. infestation of mammalian skin with Psoroptes mites. sarcoptic a. infestation of skin with Sarcoptes scabiei. See scabies (1) .

acaricide (a-kar′i-sid)
An agent that kills acarines; commonly used to denote chemicals that kill ticks. [Mod. L. acarus, a mite, fr. G. akari + L. caedo, to cut, kill]

acarid (ak′a-rid)
A general term for a member of the family Acaridae or for a mite. SYN: acaridan. [G. akari, mite]

Acaridae (a-kar′i-de)
A family of the order Acarina, a large group of exceptionally small mites, usually 0.5 mm or less, abundant in dried fruits and meats, grain, meal, and flour; frequently a cause of severe dermatitis among persons hypersensitized by frequent handling of infested products.

acaridan (a-kar′i-dan)
SYN: acarid.

Acarina (ak-a-ri′na)
An order of Arachnida that includes the mites and ticks. [G. akari, a mite]

acarine (ak′a-rin)
A member of the order Acarina.

acarodermatitis (ak′a-ro-der-ma-ti′tis)
A skin inflammation or eruption produced by a mite. [G. akari, mite, + derma (dermat-), skin] a. urticarioides infestation with the grain itch mite, Pyemotes ventricosus. See grain itch.

acaroid (ak′a-royd)
Resembling a mite. [G. akari, mite, + eidos, resemblance]

acarology (ak-a-rol′o-je)
The study of acarine parasites, the ticks and mites, and the diseases they transmit. [G. akari, mite, + logos, study]

acarophobia (ak′a-ro-fo′be-a)
Morbid fear of small parasites, small particles, or of itching. [G. akari, mite, + phobos, fear]

Acarus (ak′a-rus)
A genus of mites of the family Acaridae. [G. akari, mite] A. balatus a tropical species of mite that causes a particularly severe type of scabies-like irritation. A. folliculorum SYN: Demodex folliculorum. A. gallinae SYN: Dermanyssus gallinae. A. hordei the barley mite, a species that penetrates beneath the skin. A. rhizoglypticus hyacinthi a species of mite that develops in spoiled onions and may cause dermatitis. A. scabei former term for Sarcoptes scabiei.

acaryote (a-kar′e-ot)
SYN: akaryocyte.

acatalasemia [MIM*115500]
SYN: acatalasia.

acatalasia (a-kat-a-la′ze-a) [MIM*115500]
Absence or deficiency of catalase from blood and tissues, often manifested by recurrent infection or ulceration of the gums and related oral structures and caused by mutations in the catalase gene (CAT) on 11p. Homozygotes may have complete absence (Japanese variety) or very low levels (Swiss variety) of catalase; heterozygotes have reduced catalase levels (hypocatalasia), which overlap with the normal range. SYN: acatalasemia, Takahara disease.

acathectic (ak-a-thek′tik)
Rarely used term relating to acathexia.

acathexia (ak-a-thek′se-a)
Rarely used term for an abnormal release of secretions. [G. a- priv. + kathexis, retention]

acathexis (ak-a-thek′sis)
Rarely used term for a mental disorder in which certain objects or ideas fail to arouse an emotional response in the individual. [G. a- priv. + kathexis, retention]

acathisia (ak-a-thiz′e-a)
SYN: akathisia.

acaudal, acaudate (a-kaw′dal, a-kaw′dat)
Having no tail. [G. a- priv. + L. cauda, tail]

ACC
Abbreviation for anodal closure contraction.

accelerans (ak-sel′er-anz)
1. Accelerating. 2. Obsolete term for an accelerator (sympathetic) nerve to the heart. [L. accelerator]

accelerant (ak-sel′er-ant)
SYN: accelerator (3) .

acceleration (ak-sel-er-a′shun)
1. The act of accelerating. 2. The rate of increase in velocity per unit of time; commonly expressed in g units; also expressed in centimeters or feet per second squared. 3. The rate of increasing deviation from a rectilinear course. See radial a.. [see accelerator] angular a. the rate of change of angular velocity; e.g., when a centrifuge rotor is speeding up, or when there is a simultaneous change in velocity and direction, as in an aircraft in a tight spin. linear a. the rate of change of velocity without a change in direction; e.g., when the speed of an aircraft increases while flying a straight pathway. radial a. the centripetal a. of a particle or vehicle moving along a curved path at a constant velocity; e.g., turning a curve in an automobile, pulling out of a dive, or performing a loop maneuver in an aircraft. In aviation, a. varies directly with the square of the air speed and inversely with the radius of the turn (a = V2r, where V is air speed and r is radius of turn).

accelerator (ak-sel′er-a-ter)
1. Anything that increases rapidity of action or function. 2. In physiology, a nerve, muscle, or substance that quickens movement or response. 3. A catalytic agent used to hasten a chemical reaction. SYN: accelerant. 4. In nuclear physics, a device that accelerates charged particles ( e.g., protons) to high speed in order to produce nuclear reactions in a target, for the study of subatomic structure or for the production of radionuclides or for radiation therapy. [L. accelerans, pres. p. of ac-celero, to hasten, fr. celer, swift] linear a. (LINAC) a device imparting high velocity and energy to atomic and subatomic particles; an important device for radiation therapy. proserum prothrombin conversion a. (PPCA) obsolete term for factor VIII. prothrombin a. obsolete term for factor V. serum a. obsolete term for factor VII. serum prothrombin conversion a. (SPCA) obsolete term for factor VII.

accelerin (ak-sel′er-in)
Obsolete term for what was once considered an intermediary product of coagulation but is no longer thought to exist.

accelerometer (ak-sel-er-om′e-ter)
An instrument for measuring the rate of change of velocity per unit of time.

accentuator (ak-sent′u-a-ter)
A substance, such as aniline, the presence of which allows a combination between a tissue or histologic element and a stain that might otherwise be impossible. [L. accentus, accent, fr. cano, to sing]

acceptor (ak-sep′ter)
1. A compound that will take up a chemical group ( e.g., an amine group, a methyl group, a carbamoyl group) from another compound (the donor); under the action of alanine transaminase, l-glutamic acid is an amine donor while pyruvic acid is an amine a.. 2. A receptor that binds a hormone. [L. ac-cipio, pp. -ceptus, to accept] hydrogen a. SYN: hydrogen carrier.

accès pernicieux (ak-sa′ per-ni-syu′)
A series of severe attacks of falciparum malaria, sometimes occurring in apparently mild cases; roughly classified as cerebral and algid. [Fr., pernicious attacks or symptoms]

access (ak′ses)
A way or means of approach or admittance. In dentistry: 1. The space required for visualization and for manipulation of instruments to remove decay and prepare a tooth for restoration. 2. The opening in the crown of a tooth required to allow adequate admittance to the pulp space to clean, shape, and seal the root canal(s). SYN: a. opening. [L. accessus]

accessorius (ak-ses-o′re-us)
SYN: accessory. [L.] a. willisii SYN: accessory nerve [CN XI].

accessory (ak-ses′o-re)
In anatomy, denoting certain muscles, nerves, glands, etc. that are auxiliary or supernumerary to some similar, generally more important thing. SYN: accessorius. [L. accessorius, fr. ac-cedo, pp. -cessus, to move toward]

accident (ak′si-dent)
An unplanned or unintended but sometimes predictable event leading to injury, e.g., in traffic, industry, or a domestic setting, or such an event developing in the course of a disease. [L. ac-cido, to happen] cardiac a. sudden cardiac catastrophe, such as may result from coronary occlusion. cerebrovascular a. (CVA) an imprecise term for cerebral stroke. serum a. anaphylactic shock resulting from injection of serum of a different species for therapeutic purposes. SEE ALSO: serum sickness.

accident-prone
1. Having a greater number of accidents than would be expected of the average person in similar circumstances. 2. Having personality characteristics predisposing one to accidents.

acclimation (ak-li-ma′shun)
SYN: acclimatization.

acclimatization (a-kli′ma-ti-za′shun)
Physiological adjustment of an individual to a different climate, especially to a change in environmental temperature or altitude. SYN: acclimation.

accommodation (a-kom′o-da′shun)
1. The act or state of adjustment or adaptation. 2. In sensorimotor theory, the alteration of schemata or cognitive expectations to conform with experience. [L. ac-commodo, pp. -atus, to adapt, fr. modus, a measure] amplitude of a. the difference in refractivity of the eye at rest and when fully accommodated. a. of eye the increase in thickness and convexity of the eye's lens in response to ciliary muscle contraction in order to focus the image of an external object on the retina. histologic a. change in shape of cells to meet altered physical conditions, as the flattening of cuboidal cells in cysts as a result of pressure. SYN: pseudometaplasia. negative a. the decrease of a. that occurs when shifting from near vision to distance vision. a. of nerve the property of a nerve by which it adjusts to a slowly increasing strength of stimulus, so that its threshold of excitation is greater than it would be were the stimulus strength to have risen more rapidly. positive a. increased refractivity of the eye that occurs when shifting from the distance to a near object. range of a. the distance between an object viewed with minimal refractivity of the eye and one viewed with maximal a.. relative a. quantity of a. required for single binocular vision for any specified distance, or for any particular degree of convergence.

accommodative (a-kom′o-da-tiv)
Relating to accommodation.

accomplice (a-kom′plis)
A bacterium that accompanies the main infecting agent in a mixed infection and that influences the virulence of the main organism. [M.E., fr. O.Fr., fr. L. comples, closely connected]

accouchement (a-koosh-mawn′)
Childbirth, particularly parturition. SEE ALSO: birth. [Fr. from coucher, to lie down] a. forcé (for-sa′) forced, artificially hastened delivery, by means of forceps, version, etc.; originally applied to rapid dilation of the cervix with the hands, with version and forcible extraction of the fetus.

accoucheur (a-koo-sher′)
Obsolete term for obstetrician.

accrementition (ak′re-men-tish′un)
1. Reproduction by budding or germination. 2. SYN: accretion (1) . [L. accresco, pp. -cretus, to increase]

accretio cordis (a-kre′she-o kor′dis)
Adhesion of the pericardium to adjacent extracardiac structures.

accretion (a-kre′shun)
1. Increase by addition to the periphery of material of the same nature as that already present; e.g., the manner of growth of crystals. SYN: accrementition (2) . 2. In dentistry, foreign material (usually plaque or calculus) collecting on the surface of a tooth or in a cavity. 3. A growing together. [L. accretio, fr. ad, to, + crescere, to grow]

accrochage (ak-ro-shahj′)
Intermittent synchronization of two different rhythms of the heart with one influencing the behavior of the other when neither is dominant; seen in cases of atrioventricular dissociation when an atrial beat falls shortly after a ventricular beat, the latter causing the atrial beat to occur sooner than expected. [Fr. hooking, hitching]

accuracy (ak′ku-ra-se)
The degree to which a measurement, or an estimate based on measurements, represents the true value of the attribute that is being measured. In the laboratory, a. of a test is determined when possible by comparing results from the test in question with results generated using reference standards or an established reference method.

ACD
Abbreviation for acid-citrate-dextrose.

ACE
Abbreviation for angiotensin-converting enzyme.

acebutolol (as-e-bu′to-lol)
A β-adrenergic blocking agent.

aceclidine (a-sek′li-den)
A cholinergic drug used for topical therapy of glaucoma.

acedapsone (as-e-dap′son)
A derivative of dapsone with a longer duration of action; used to enhance the malaria chemoprophylaxis of quinine or of a combination of chloroquine-primaquine, and believed to act by interference with the utilization of folic acid.

acedia (a-se-de′-a)
Obsolete term for a mental syndrome, the chief features of which are listlessness, carelessness, apathy, and melancholia.

acefylline piperazine (a-sef′i-len)
A diuretic and smooth muscle relaxant.

ACEI
Abbreviation for angiotensin-converting enzyme inhibitors, under inhibitor.

acellular (a-sel′u-lar)
1. Devoid of cells. SYN: noncellular (2) . 2. A term applied to unicellular organisms that do not become multicellular and are complete within a single cell unit; frequently applied to protozoans to emphasize their complete organization within a single cell. [G. a- priv. + L. cellula, a small chamber]

acelom (a-se′lom)
Absence of a true celom or body cavity lined with mesothelium; typically found in Platyhelminthes (flatworms), which have a syncytial mass of parenchymal cells instead of a true body cavity. [G. a- priv. + koiloma, hollow (celom)]

acelomate, acelomatous (a-se′lo-mat, a-se-lo′ma-tus)
Not having a celom or body cavity.

acenocoumarin (a-se-no-koo′ma-rin)
SYN: acenocoumarol.

acenocoumarol (a-se-no-koo′ma-rol)
An orally effective synthetic anticoagulant of the coumarin type, with similar actions. SYN: acenocoumarin, nicoumalone.

acentric (a-sen′trik)
Lacking a center; in cytogenetics, denoting a chromosome fragment without a centromere. [G. a- priv. + kentron, center]

acephalia, acephalism (a-se-fa′le-a, a-sef′a-lizm)
1. SYN: acephaly. 2. SYN: acephalus.

acephaline (a-sef′a-lin)
Denoting members of the protozoan suborder Acephalina (order Eugregarinida), characterized by simple noncompartmentalized bodies, that parasitize invertebrates.

acephalobrachia (a-sef′a-lo-bra′ke-a)
SYN: abrachiocephaly. [G. a- priv. + kephale, head, + brachion, arm]

acephalocardia (a-sef′a-lo-kar′de-a)
Absence of head and heart as seen in a parasitic twin. [G. a- priv. + kephale, head, + kardia, heart]

acephalocheiria, acephalochiria (a-sef′a-lo-ki′re-a)
Congenital absence of head and hands. [G. a- priv. + kephale, head, + cheir, hand]

acephalocyst (a-sef′a-lo-sist)
A hydatid cyst with no daughter cyst; a sterile hydatid, so called because it fails to develop scoleces (tapeworm heads). [G. a- priv. + kephale, head, + kystis, bladder]

acephalogasteria (a-sef′a-lo-gas-ter′e-a)
Congenital absence of head, thorax, and abdomen as seen in a parasitic twin with pelvis and legs only.

acephalopodia (a-sef′a-lo-po′de-a)
Congenital absence of head and feet. [G. a- priv. + kephale, head, + pous, foot]

acephalorrhachia (a-sef′a-lo-rak′e-a)
Congenital absence of head and vertebral column. [G. a- priv. + kephale, head, + rhachis, spine]

acephalothoracia (a-sef′a-lo-thor-ase-a)
Congenital absence of head and thorax. [G. a- priv. + kephale, head, + thorax, chest]

acephalous (a-sef′a-lus)
Headless.

acephalus (a-sef′a-lus)
A headless fetus. SYN: acephalia (2) , acephalism. [G. a- priv. + kephale, head] a. acormus (a-kor′mus) condition in which a head without a body is attached to the placenta by an umbilical cord. a. dibrachius a fetus lacking a head but having two recognizably developed upper limbs. a. dipus a fetus lacking a head but showing two recognizably developed lower limbs. a. monobrachius a fetus lacking a head and showing only one recognizable upper limb. a. monopus a fetus lacking a head and with fusion of the lower extremities so extreme that only a single foot is recognizable. a. sympus a fetus lacking a head and showing fusion of the lower limbs.

acephaly (a-sef′a-le)
Congenital absence of the head. SYN: acephalia (1) , acephalism. [G. a- priv. + kephale, head]

acerola (a-se-ro-la)
Fruit of a bushy tree that grows in Central and South America and Puerto Rico. The berry is the richest known source of vitamin C (ascorbic acid).

acervulus (a-ser′vu-lus)
SYN: corpora arenacea, under corpus. [Mod. L. dim. of L. acervus, a heap]

acestoma (a-ses-to′ma)
Exuberant granulations that form a cicatrix. [G. akestos, curable, + -oma, tumor]

acesulfame (a-se-sul-fam)
A synthetic, noncaloric sweetener similar to saccharin.

acet-, aceto-
Combining forms denoting the two-carbon fragment of acetic acid.

acetabula (as-e-tab′u-la)
Plural of acetabulum.

acetabular (as-e-tab′u-lar)
Relating to the acetabulum.

acetabulectomy (as′e-tab-u-lek′to-me)
Excision of the acetabulum. [acetabulum + G. ektome, excision]

acetabuloplasty (as-e-tab′u-lo-plas-te)
Any operation aimed at restoring the acetabulum to as near a normal state as possible. [acetabulum + G. plastos, formed]

acetabulum, pl .acetabula (as-e-tab′u-lum, -la) [TA]
A cup-shaped depression on the external surface of the hip bone, with which the head of the femur articulates. SYN: cotyle (2) , cotyloid cavity. [L. a shallow vinegar vessel or cup]

acetal (as′e-tal)
Product of the addition of 2 mol of alcohol to one of an aldehyde, thus: RCHO + 2R′OH → RCH(OR′)2 + H2O; in mixed acetals ( e.g., glycosides), two different alcohols are bound to the original aldehyde group. SEE ALSO: hemiacetal, hemiketal, ketal. a. phosphatide older trivial name for alk-1-enylglycerophospholipid.

acetaldehyde (as-e-tal′de-hid)
An intermediate in yeast fermentation of carbohydrate and in alcohol metabolism. It is a central agent for the toxic effects of ethanol. SYN: acetic aldehyde, ethanal. activated a. the activated form of a. that is formed during the decarboxylation of active pyruvate. Formed in alcohol fermentation and in carbohydrate metabolism. SYN: α-hydroxyethylthiamin pyrophosphate.

acetamide (as-et-am′id, a-set′a-mid)
CH3CONH2;used in biomedical research. SYN: acetic amide.

2-acetamidofluorene (AAF) (as′et-am′i-do-flor′en)
SYN: 2-acetylaminofluorene.

acetaminophen (as-et-a-me′no-fen)
An antipyretic and analgesic, with potency similar to aspirin. SYN: paracetamol.

acetaminosalol (as-e-tam′in-o-sal′ol)
Used as an analgesic, antipyretic, and intestinal antiseptic. SYN: phenetsal.

acetarsol (as-e-tar′sol)
SYN: acetarsone.

acetarsone (as-e-tar′son)
Used in the treatment of amebiasis, and as a local application in Vincent angina and in trichomoniasis vaginitis. The diethylamine salt is used as an antisyphilitic. SYN: acetarsol.

acetate (as′e-tat)
A salt or ester of acetic acid. active a. SYN: acetyl-CoA. a. kinase [EC 2.7.2.1] a phosphotransferase forming acetyl phosphate and ADP from ATP and a.. An important enzyme in the formation of “high-energy” phosphate in certain microorganisms. SYN: acetokinase. a. thiokinase SYN: acetyl-CoA ligase.

acetate-CoA ligase
SYN: acetyl-CoA ligase.

acetazolamide (as′e-ta-zol′a-mid)
The heterocyclic sulfonamide, 5-acetylamido-1,3,4-thiadiazole-2-sulfonamide, which inhibits the action of carbonic anhydrase in the kidney, increasing the urinary excretion of sodium, potassium, and bicarbonate, reducing excretion of ammonium, raising the pH of the urine, and lowering the pH of the blood; used in respiratory acidosis for diuresis and to stimulate respiratory drive, in glaucoma to reduce intraocular pressure, and in epilepsy. A. sodium has the same actions and uses as a., but is more soluble and thus more suitable for parenteral administration.

acetenyl (a-se′ten-il)
SYN: ethynyl.

acetic (a-se′tik, -set′ik)
1. Denoting the presence of the two-carbon fragment of a. acid. 2. Relating to vinegar; sour. [L. acetum, vinegar]

acetic acid
A product of the oxidation of ethanol and of the destructive distillation of wood; used locally as a counterirritant and occasionally internally, and also as a reagent; contained in vinegars. SYN: ethanoic acid. diluted a. contains 6% w/v of a.. glacial a. contains 99% absolute a.; a caustic for removal of corns and warts.

acetic aldehyde
SYN: acetaldehyde.

acetic amide
SYN: acetamide.

aceticoceptor (a-se′ti-ko-sep′tor)
A side chain of molecules with a special affinity for the acetic acid radical. [L. acetum, vinegar, + capio, to take]

acetify (a-set′i-fi)
To cause acetic fermentation; to make vinegar or become vinegar. [L. acetum, vinegar, + facio, to make; or fieri, to be made, to become]

acetimeter (as-e-tim′e-ter)
An apparatus for determining the content of acetic acid in vinegar or other fluid. SYN: acetometer. [L. acetum, vinegar, + G. metron, measure]

aceto-
See acet-.

acetoacetate (as′e-to-as′e-tat)
A salt or ion of acetoacetic acid. A ketone body formed in ketogenesis. SYN: diacetate (1) . a. decarboxylase [EC 4.1.1.4] a carboxy-lyase cleaving CO2 from a. to form acetone.

acetoacetic acid (as′e-to-a-se′tik)
One of the ketone bodies, formed in excess and appearing in the urine in starvation or diabetes.

acetoacetyl-CoA (as′e-to-a-se′til)
Intermediate in the oxidation of fatty acids and in the formation of ketone bodies; also formed from two molecules of acetyl-CoA; major role is condensation with acetyl-CoA to form the important β-hydroxy-β-methylglutaryl-CoA. SYN: acetoacetyl-coenzyme A. acetoacetyl-CoA reductase [EC 1.1.1.36] an oxidoreductase catalyzing interconversion of a 3-oxoacyl-CoA and NADPH, and the corresponding d-3-hydroxyacyl-CoA, and NADP+. A step in fatty acid synthesis. acetoacetyl-CoA thiolase SYN: acetyl-CoA acetyltransferase.

acetoacetyl-coenzyme A (as′e-to-as′e-til-ko-en′zim)
SYN: acetoacetyl-CoA.

acetoacetyl-succinic thiophorase (as′e-to-as′e-til-suk-sin′ik)
SYN: 3-oxoacid-CoA transferase.

acetohexamide (as-e-to-heks′a-mid)
An oral hypoglycemic agent that stimulates pancreatic insulin secretion; most useful therapeutically in mild cases of non-insulin-dependent diabetes mellitus.

acetohydroxamic acid (as′e-to-hi-drok′sa-mik)
An inhibitor of urease, used as adjunctive therapy in chronic urea-splitting urinary infections.

acetoin (as-et′-o-in)
A condensation product of two molecules of acetaldehyde.

acetokinase (as′e-to-ki′nas)
SYN: acetate kinase.

acetol (as′e-tol)
Obsolete term for 1-hydroxy-2-propanone, or hydroxyacetone; also used as a proprietary name for certain commercial items.

α-acetolactic acid (as′e-to-lak′tik)
An intermediate in pyruvic acid catabolism and valine biosynthesis.

acetolysis (as-e-tol′i-sis)
Decomposition of an organic compound with the addition of the elements of acetic acid at the point of decomposition; analogous to hydrolysis and phosphorolysis.

acetomenaphthone (as′e-to-me-naf′thon)
SYN: menadiol diacetate.

acetometer (as-e-tom′e-ter)
SYN: acetimeter.

acetone (as′e-ton)
A colorless, volatile, flammable liquid; extremely small amounts are found in normal urine, but larger quantities occur in urine and blood of diabetic persons, sometimes imparting an ethereal odor to the urine and breath. It is one of the ketone bodies. The synthetic is used as a solvent in some pharmaceutical and commercial preparations. SYN: dimethyl ketone.

acetonemia (as′e-to-ne′me-a)
The presence of acetone or acetone bodies in relatively large amounts in the blood, manifested at first by erethism, and later by a progressive depression. [acetone + G. haima, blood]

acetonemic (as′e-to-ne′mik)
Relating to or caused by acetonemia.

acetonitrile (as′e-to-ni′tril)
Methyl cyanide;a colorless fluid of aromatic odor, soluble in water and alcohol.

acetonuria (as′e-to-noor′e-a)
Excretion in the urine of large amounts of acetone, an indication of incomplete oxidation of large amounts of lipids; commonly occurs in diabetic acidosis. [acetone + G. ouron, urine]

acetophenazine maleate (as-e-to-fe′na-zen mal′e-at)
A phenothiazine tranquilizer.

acetophenetidin (as′e-to-fe-net′i-din)
SYN: phenacetin.

acetosulfone sodium (as′e-to-sul′fon)
A leprostatic administered orally.

acetous (as′e-tus)
Relating to vinegar; sour-tasting.

acetowhitening (a-se′to- hwit′en-ing)
Blanching of skin or mucous membranes after application of 3–5% acetic acid solution, a sign of increased cellular protein and increased nuclear density; used particularly on genital skin and mucous membranes, including the uterine cervix, to identify zones of squamous cell change for biopsy and condyloma acuminatum for treatment. SYN: visual inspection with acetic acid. [acetic acid + whitening]

acetrizoate sodium (as-e-tri-zo′at)
Salt of 3-acetamido-2,4,6-triiobenzoic acid, a formerly used water-soluble radiographic contrast medium.

acetum, pl .aceta (a-se′tum, -ta)
SYN: vinegar. [L. vinum a., soured wine, vinegar]

aceturate (a-set′u-rat)
USAN-approved contraction for N-acetylglycinate, CH3CONHCH2COO-.

acetyl (Ac) (as′e-til)
CH3CO–;an acetic acid molecule from which the hydroxyl group has been removed. a. chloride a colorless liquid used as a reagent; also corrosive, causing severe burns because of hydrolysis to HCl. a. phosphate a “high-energy” phosphate that acts as an acetate donor in the metabolism of various bacteria. a. transacylase SYN: ACP-acetyltransferase.

acetyladenylate (as′e-til-a-den′il-at)
Mixed anhydride between the carboxyl group of acetic acid and the phosphoric residue of adenosine 5′-monophosphoric acid.

2-acetylaminofluorene (AAF) (as′e-til-am′i-no-flor′en)
A potent carcinogenic compound. SYN: 2-acetamidofluorene.

acetylase (a-set′il-as)
Any enzyme catalyzing acetylation or deacetylation, as in the formation of N-acetylglutamate from glutamate plus acetyl-CoA, or the reverse; acetylases are usually called acetyltransferases.

acetylation (a-set-i-la′shun)
Formation of an acetyl derivative.

acetylcarbromal (a-se′til-kar-bro′mal)
A sedative replaced by benzodiazepines and newer drugs.

acetylcholine (ACH, Ach) (as-e-til-ko′len)
The acetic ester of choline, the neurotransmitter substance at cholinergic synapses, which causes cardiac inhibition, vasodilation, gastrointestinal peristalsis, and other parasympathetic effects. It is liberated from preganglionic and postganglionic endings of parasympathetic fibers and from preganglionic fibers of the sympathetic as a result of nerve injuries, whereupon it acts as a transmitter on the effector organ; it is hydrolyzed rapidly into choline and acetic acid by acetylcholinesterase in the tissues and by pseudocholinesterase in the blood. a. chloride a miotic, administered as an ophthalmic solution for parasympathomimetic effect; used in cataract surgery.

acetylcholinesterase (as′e-til-ko-lin-es′ter-as)
The cholinesterases that hydrolyze acetylcholine to acetate and choline within the central nervous system and at peripheral neuroeffector junctions ( e.g., motor endplates and autonomic ganglia). SYN: choline esterase I, “e”-type cholinesterase, specific cholinesterase, true cholinesterase.

acetyl-CoA
Condensation product of coenzyme A and acetic acid, symbolized as CoAS∼COCH3; intermediate in transfer of two-carbon fragment, notably in its entrance into the tricarboxylic acid cycle and in fatty acid synthesis. SYN: acetyl-coenzyme A, active acetate. acetyl-CoA acetyltransferase an acetyltransferase forming acetoacetyl-CoA from two molecules of acetyl-CoA, releasing one CoA. A key step in ketogenesis and sterol synthesis. SYN: acetoacetyl-CoA thiolase, acetyl-CoA thiolase, thiolase. acetyl-CoA acylase SYN: acetyl-CoA hydrolase. acetyl-CoA acyltransferase an enzyme catalyzing the thioclastic cleavage by coenzyme A of β-ketoacyl-CoA, forming an acyl-CoA with a carbon chain shorter by two atoms, the missing two atoms appearing as acetyl-CoA. A step in fatty acid degradation. SEE ALSO: acetyl-CoA acetyltransferase. SYN: 3-ketoacyl-CoA thiolase, β-ketothiolase. acetyl-CoA carboxylase a ligase that catalyzes the reaction of acetyl-CoA, CO2, H2O, and ATP, with a divalent cation as catalyst and covalently bound biotin, to form malonyl-CoA, ADP, and Pi (or the reverse decarboxylase); N-carboxybiotin is an intermediate. A crucial enzyme in fatty acid synthesis. acetyl-CoA deacylase SYN: acetyl-CoA hydrolase. acetyl-CoA:α-glucosaminide acetyltransferase an enzyme involved in the synthesis of certain carbohydrate moieties on proteins. A deficiency of this enzyme leads to mucopolysaccharidosis type III C. acetyl-CoA hydrolase a hydrolase that cleaves acetate and coenzyme A from acetyl-CoA. SYN: acetyl-CoA acylase, acetyl-CoA deacylase. acetyl-CoA ligase a ligase that catalyzes the reaction of acetate and CoA and ATP to form AMP, pyrophosphate, and acetyl-CoA. A key step in the activation of acetate. SYN: acetate thiokinase, acetate-CoA ligase, acetyl-activating enzyme, acetyl-CoA synthetase. acetyl-CoA synthetase SYN: acetyl-CoA ligase. acetyl-CoA thiolase SYN: acetyl-CoA acetyltransferase.

acetyl-coenzyme A (as′e-til-ko-en′zim)
SYN: acetyl-CoA.

acetylcysteine (as′e-til-sis′te-in)
A mucolytic agent that reduces the viscosity of mucous secretions; used to prevent liver injury produced by acetaminophen toxicity.

acetyldigitoxin (a-se′til-dij-i-tok′sin)
The α-acetyl ester of digitoxin derived from lanatoside A, having the same actions and uses as digitoxin, but more rapid onset and shorter duration of action.

acetyldigoxin (a-se′til-di-jok′sin)
A digitalis glycoside with properties similar to those of digoxin; derived from digilanide C.

α-N-acetylgalactosaminidase (as′e-til-gal-ak-tos-a-min-i-das)
An enzyme that hydrolyzes 2-acetamido-2-deoxy-α-d-galactosides to the alcohol and free 2-acetamido-2-deoxy-d-galactose. A deficiency of this enzyme will result in Schindler disease.

α-N-acetylglucosaminidase (as′e-til-glu-cos-a-min-i-das)
An enzyme that hydrolyzes glycosides of N-acetylglucosamine producing the alcohol and N-acetylglucosamine. A deficiency of this enzyme results in mucopolysaccharidosis III B.

acetylmethadol (as′e-til-meth-a-dol)
An opioid analgesic which exists in 4 different optical isomers. The l isomers are active and l-a. (LAM) has a long duration of action and has been tried as a substitute for methadone in methadone maintenance programs and in programs where methadone is to be withdrawn, as in physical dependence of the morphine type.

acetylornithine deacetylase (as′e-til-or′ni-then) [EC 3.5.1.16]
An enzyme catalyzing the hydrolysis of N2-acetyl-l-ornithine to l-ornithine and acetate.

3-acetylpyridine (as′e-til-pir′i-den)
An antimetabolite of nicotinamide that produces symptoms of nicotinamide deficiency in mice; a neurotoxin that damages hypothalamus, brainstem, and basal ganglia.

acetylsalicylic acid (as′e-til-sal-i-sil′ik)
SYN: aspirin.

acetyl sulfisoxazole
A derivative of sulfisoxazole with the same actions and uses; an antibacterial sulfa drug.

acetyltannic acid (as′e-til-tan′ik)
An astringent formerly used for treatment of diarrhea. SYN: diacetyltannic acid, tannylacetate.

acetyltransferase (as′e-til-trans′fer-as)
Any enzyme transferring acetyl groups from one compound to another. SEE ALSO: acetyl-CoA a., choline a., dihydrolipoamide S-a.. SYN: transacetylase.

AcG, ac-g
Abbreviation for accelerator globulin.

ACH, Ach
Abbreviation for acetylcholine.

Ach
See ACH.

achalasia (ak-a-la′-ze-a)
Failure to relax; referring especially to visceral openings such as the pylorus, cardia, or any other sphincter muscles. [G. a- priv. + chalasis, a slackening] a. of the cardia SYN: esophageal a.. cricopharyngeal a. functional obstruction at the level of the upper esophageal sphincter due to failure of relaxation of the cricopharyngeal muscles; often associated with a pharyngoesophageal diverticulum. SYN: a. of the upper sphincter, hypertensive upper esophageal sphincter. esophageal a. failure of normal relaxation of the lower esophageal sphincter associated with uncoordinated contractions of the thoracic esophagus, resulting in functional obstruction and difficulty swallowing. SYN: a. of the cardia, cardiospasm. a. of the upper sphincter SYN: cricopharyngeal a..

Achard
Emile C., French physician, 1860–1941. See A. syndrome, A.-Thiers syndrome.

ache (ak)
A dull, poorly localized pain, usually one of less than severe intensity. bone a. a dull pain in one or more bones, often severe; an extreme variety occurs in dengue. stomach a. pain in the abdomen, usually arising in the stomach or intestine. SYN: gastralgia, gastrodynia.

acheilia (a-ki′le-a)
Congenital absence of the lips. [G. a- priv. + cheilos, lip]

acheilous, achilous (a-ki′lus)
Characterized by or relating to acheilia.

acheiria (a-ki′re-a)
1. Congenital absence of one or both hands. 2. Anesthesia in, with loss of the sense of possession of, one or both hands. 3. A form of dyscheiria in which the patient is unable to tell on which side of the body a stimulus has been applied. [G. a- priv. + cheir, hand]

acheiropody, achiropody (a-ki-rop′o-de, a-ki-rop′o-de) [MIM*200500]
Congenital absence of the hands and feet; autosomal recessive inheritance. [G. a- priv. + cheir, hand, + podos, foot]

acheirous, achirous (a-ki′rus)
Characterized by or relating to acheiria (1).

Achenbach
Walter, 20th century German internist. See A. syndrome.

Achilles
Mythical Greek warrior, vulnerable only in the heel. See A. bursa, A. reflex, A. tendon.

achillobursitis (a-kil′o-ber-si′tis)
Inflammation of a bursa in proximity to the tendo calcaneus. SYN: retrocalcaneobursitis.

achillotenotomy (a-kil′o-ten-ot′o-me)
Cutting the Achilles tendon. [Achilles (tendon) + G. tenon, tendon, + tome, a cutting]

achiral (a-ki′ral)
Not chiral; denoting an absence of chirality. [G. a- priv. + cheir, hand]

achlorhydria (a-klor-hi′dre-a)
Absence of hydrochloric acid from the gastric juice. [G. a- priv. + chlorhydric (acid)]

achlorophyllous (a-klor-of′i-lus)
Without chlorophyll, as in fungi.

Acholeplasma, pl .Acholeplasmata (a-ko-le-plas′ma, mah-ta)
A genus of bacteria (order Mycoplasmatales) that have characteristics identical to those of the species in the genus Mycoplasma, with the exception that the acholeplasmas do not require sterol for growth; saprophytic and parasitic species occur. The type species is A. laidlawii. A. axanthum a species originally found in a murine leukemia cell line; ecology bovine, porcine, botanical. A. laidlawii a species that occurs as a saprophyte in sewage, manure, humus, and soil; type species of the genus A.. SYN: Mycoplasma laidlawii.

acholia (a-ko′le-a)
Suppressed or absent secretion of bile. [G. a- priv. + chole, bile]

acholic (a-kol′ik)
Without bile, as in a. (pale) stools.

acholuria (a-ko-loo′re-a)
Absence of bile pigments from the urine in certain cases of jaundice. [G. a- priv. + chole, bile, + ouron, urine]

acholuric (a-ko-loo′rik)
Without bile in the urine.

achondrogenesis (a-kon-dro-jen′e-sis)
Neonatal lethal dwarfism characterized by severe bone dysplasia of all four limbs, micromelia, enlarged skull, and a short trunk with delayed or absent ossification of the lower spine and pubic bones. There are various types. [G. a- priv. + chondros, cartilage, + genesis, origin] Type IA a. [MIM*200600] a. with hypervascular cartilage and hypercellular bone; uncertain inheritance pattern. SYN: Houston-Harris syndrome. Type IB a. [MIM*600972] a. with severely disorganized intracartilaginous ossification; autosomal recessive inheritance, caused by mutation in the diastrophic dysplasia sulfate transporter gene (DTDST) on chromosome 5q. SYN: Parenti-Fraccaro syndrome. Type II a. [MIM*200610] a. with autosomal dominant inheritance, caused by mutation in the collagen type II gene (COL2A1) on chromosome 12q. SYN: Langer-Saldino syndrome.

achondroplasia (a-kon-dro-pla′ze-a) [MIM*100800 *134934]
This chondrodystrophy, characterized by an abnormality in conversion of cartilage to bone, is the most common form of short-limb dwarfisim; characterized by short stature with rhizomelic shortening of the limbs, large head with frontal bossing and midface hypoplasia, exaggerated lumbar lordosis, limitation of elbow extension, genu varum, trident hand, characteristic radiographic skeletal findings, and neurologic symptoms complicating hydrocephalus and spinal canal stenosis. Autosomal dominant inheritance with most cases sporadic, caused by mutation in the fibroblast growth factor receptor 3 gene (FGFR3) on chromosome 4p. [G. a- priv. + chondros, cartilage, + plasis, a molding] homozygous a. severe a. caused by inheritance of two a. alleles, one from each parent; usually fatal in the first year of life.

achondroplastic (a-kon-dro-plas′tik)
Relating to or characterized by achondroplasia.

achordate, achordal (a-kor′dat, a-kor′dal)
Referring to animal forms below the Chordata that do not develop a notochord or chorda.

achoresis (a-ko-re′sis)
Permanent contraction of a hollow viscus, such as the stomach or bladder, whereby its capacity is reduced. [G. a- priv. + choreo, to make room, fr. choros, space]

Achorion (a-ko′re-on)
Former name for dermatophytes now placed in the genus Trichophyton or Microsporum. [G. achor, dandruff]

achroacyte (a-kro′a-sit)
A colorless cell. [G. a- priv. + chroa, color, + kytos, a hollow (cell)]

achrodextrin (ak-ro-deks′trin)
SYN: achroodextrin. [G. a- priv. + chroma, color, + dextrin]

achromacyte (a-kro′ma-sit)
SYN: achromocyte.

achromasia (ak-ro-ma′se-a)
1. Pallor associated with hippocratic facies, emaciation, and weakness, often heralding a moribund state. SYN: cachectic pallor. 2. SYN: achromia. [G. achromos, colorless]

achromat (a-kro′mat)
A person exhibiting achromatopsia. [G. a- priv. + chroma, color]

achromatic (ak-ro-mat′ik)
1. Colorless. 2. Not staining readily. 3. Refracting light without chromatic aberration. [G. a- priv. + chroma, color]

achromatin (a-kro′ma-tin)
The weakly staining components of the nucleus, such as the nuclear sap and euchromatin.

achromatinic (a-kro-ma-tin′ik)
Relating to or containing achromatin.

achromatism (a-kro′ma-tizm)
1. The quality of being achromatic. 2. The annulment of chromatic aberration by combining glasses of different refractive indexes and different dispersion.

achromatocyte (a-kro-mat′o-sit)
SYN: achromocyte.

achromatolysis (a-kro-ma-tol′i-sis)
Dissolution of the achromatin of a cell or of its nucleus. SYN: karyoplasmolysis.

achromatophil (a-kro-mat′o-fil)
1. Not being colored by the histologic or bacteriologic stains. SYN: achromophilic, achromophilous. 2. A cell or tissue that cannot be stained in the usual way. SYN: achromophil. [G. a- priv. + chroma, color, + philos, fond]

achromatophilia (a-kro′mat-o-fil′e-a)
A condition of being refractory to staining processes.

achromatopsia, achromatopsy (a-kro-ma-top′se-a, a-kro′ma-top-se) [MIM*216900]
This is the compete form of a., characterized by severe deficiency of color perception, associated with nystagmus, photophobia, reduced visual acuity, and “day blindness”; autosomal recessive inheritance, caused by mutation in the cone photoreceptor cGMP-gated cation channel, alpha-subunit 3 gene (CNGA3) on chromosome 2q. SYN: achromatic vision, monochromasia, monochromasy, monochromatism (2) . [G. a- priv. + chroma, color, + opsis, vision] atypical a. incomplete a. with normal visual acuity and no nystagmus. Cf.:dyschromatopsia. complete a. a. with absent color vision, nystagmus, reduced visual acuity, and light aversion. SYN: rod monochromatism, typical a.. incomplete a. [MIM*200930] impaired but not absent color vision with less severely reduced visual acuity than in complete a., associated with photophobia and nystagmus; autosomal recessive inheritance. An autosomal dominant [MIM*180020] form and several X-linked [MIM*304020, MIM*300085, and MIM*303700] forms exist. typical a. SYN: complete a..

achromatosis (a-kro-ma-to′sis)
SYN: achromia. [G. a- priv. + chroma, color]

achromatous (a-kro′ma-tus)
Colorless.

achromaturia (a-kro-ma-too′re-a)
The passage of colorless or very pale urine. [G. a- priv. + chroma, color, + ouron, urine]

achromia (a-kro′me-a)
1. Hypopigmentation; absence or loss of natural pigmentation of the skin and iris; may be congenital or acquired. SEE ALSO: depigmentation. 2. Lack of capacity to accept stains in cells or tissue. SYN: achromasia (2) , achromatosis. [G. a- priv. + chroma, color] a. parasitica a phase of lessening or absence of pigmentation in cutaneous lesions, caused by the fungus Malassezia furfur. SEE ALSO: tinea versicolor.

achromic (a-kro′mik)
Colorless.

Achromobacter (a′kro-mo-bak′ter)
A Gram-negative bacterial genus of uncertain clinical significance, closely related to members of the Alcaligenes and Ochrobactrum species.

achromocyte (a-kro′mo-sit)
A hypochromic, crescent-shaped erythrocyte, probably resulting from artifactual rupture of a red cell with loss of hemoglobin. SYN: achromacyte, achromatocyte, ghost corpuscle, phantom corpuscle, Ponfick shadow, shadow corpuscle, shadow (3) , Traube corpuscle. [G. a- priv. + chroma, color, + kytos, hollow (cell)]

achromophil (a-kro′mo-fil)
SYN: achromatophil.

achromophilic, achromophilous (a-kro-mo-fil′ik, a-kro-mof′i-lus)
SYN: achromatophil (1) .

achromotrichia (a-kro-mo-trik′e-a)
Absence or loss of pigment in the hair. SEE ALSO: canities. [G. a- priv. + chroma, color, + thrix, hair]

achroodextrin (ak-ro′o-deks′trin)
Dextrin of low molecular weight, formed from starch in a stage of the digestion of the latter by amylase; it gives no color reaction with iodine. Cf.:amylodextrin, erythrodextrin. SYN: achrodextrin. [G. achromos, uncolored, + dextrin]

achylia (a-ki′le-a)
1. Absence of gastric juice or other digestive secretions. 2. Absence of chyle. [G. a- priv. + chylos, juice] a. gastrica diminished or abolished secretion of gastric juice associated with atrophy of the mucous membrane of the stomach. a. pancreatica deficiency or absence of pancreatic secretion, usually resulting in fatty stools, emaciation, and impaired nutrition.

achylous (a-ki′lus)
1. Lacking in gastric juice or other digestive secretions. 2. Having no chyle. [G. achylos, without juice]

acicular (a-sik′u-lar)
Needle-shaped or needle-pointed; applied particularly to leaves and crystals. [L. a., small pin]

acid (as′id)
1. A compound yielding a hydrogen ion in a polar solvent ( e.g., in water); acids form salts by replacing all or part of the ionizable hydrogen with an electropositive element or radical. 2. In popular language, any chemical compound that has a sour taste (given by the hydrogen ion). 3. Sour; sharp to the taste. 4. Relating to a.; giving an a. reaction. For individual acids, see specific names. [L. acidus, sour] bile acids steroid acids found in bile; e.g., taurocholic and glycocholic acids, used therapeutically when biliary secretion is inadequate and for biliary colic. Their physiologic roles include fat emulsification. Their synthesis is reduced in disorders of the peroxisomes. Br&slash;onsted a. an a. that is a proton donor. conjugate a. the protonated compound of two compounds that differ in structure only by the presence of the labile proton. dibasic a. an a. containing two ionizable atoms of hydrogen in the molecule. See a. (1) . fatty a. fatty a.. inorganic a. an a. made up of molecules not containing organic radicals; e.g., HCl, H2SO4, H3PO4. Lewis a. an a. that is an electron pair acceptor. monobasic a. an a. containing one ionizable atom of hydrogen in the molecule. See a. (1) . organic a. an a. made up of molecules containing organic radicals; e.g., acetic a., citric a., which contain the ionizable &cbond;COOH group. polybasic a. an a. containing more than three ionizable atoms of hydrogen in the molecule. See a. (1) . wax a. a long-chain monocarboxylic a. with an even number of carbons, often found esterified in waxes ( e.g., lauric a.).

acid-citrate-dextrose (ACD)
A citrate anticoagulant used for the collection and preservation of whole blood. It has largely been replaced by newer anticoagulants (CPD, Adsol) that allow for longer shelf life for blood and blood products.

acidemia (as-i-de′me-a)
An increase in the H-ion concentration of the blood or a fall below normal in pH. Individual types of a. are listed by specific name, e.g., isovalericacidemia, aminoacidemia, etc. [acid + G. haima, blood]

acid-fast (as′id-fast)
Denoting bacteria that are not decolorized by acid-alcohol after having been stained with dyes such as basic fuchsin; e.g., the mycobacteria and nocardiae.

acidify (a-sid′i-fi)
1. To render acid. 2. To become acid.

acidity (a-sid′i-te)
1. The state of being acid. 2. The acid content of a fluid. total a. (a) an obsolete expression of gastric a., the a. being determined by titration with sodium hydroxide, using phenolphthalein as indicator.

acidophil, acidophile (a-sid′o-fil, a-sid′o-fil)
1. One of the acid-staining cells of the anterior pituitary. 2. A microorganism that grows well in a highly acid medium. [acid + G. philos, fond]

acidophilic (as′i-do-fil′ik, a-sid′o-fil-ik)
Having an affinity for acid dyes; denoting a cell or tissue element that stains with an acid dye, such as eosin. SYN: oxychromatic.

acidosis (as-i-do′sis)
A pathologic state characterized by an increase in the concentration of hydrogen ions in the arterial blood above the normal level, 40 nmol/L, or pH 7.4; may be caused by an accumulation of carbon dioxide or acidic products of metabolism, or by a decrease in the concentration of alkaline compounds. [acid + G. -osis, condition] carbon dioxide a. SYN: respiratory a.. compensated a. an a. in which the pH of body fluids is normal; compensation is achieved by respiratory or renal mechanisms. compensated respiratory a. retention of bicarbonate by the renal tubules to minimize the effect on the pH of the blood of retention of carbon dioxide by the lungs, such as occurs with hypoventilation. diabetic a. a type of metabolic a. caused by accumulation of ketone bodies in diabetes mellitus. hypercapnic a. SYN: respiratory a.. hyperchloremic a. SYN: renal tubular a.. lactic a. a type of metabolic a. caused by accumulation of lactic acid due to tissue hypoxia, drug effect, or unknown etiology. metabolic a. decreased pH and bicarbonate concentration in the body fluids caused either by the accumulation of acids or by abnormal losses of fixed base from the body, as in diarrhea or renal disease. primary renal tubular a. a metabolic defect in the mechanism of urinary acidification that may be either the transient type, with onset in infancy, or the persistent type, with onset in childhood or adult years; both types are familial. renal tubular a. a clinical syndrome characterized by decreased ability to acidify urine, and by low plasma bicarbonate and high plasma chloride concentrations, often with hypokalemia; often complicated by osteomalacia, nephrocalcinosis, or renal calculi. SEE ALSO: primary renal tubular a., secondary renal tubular a.. SYN: hyperchloremic a.. respiratory a. a. caused by retention of carbon dioxide; due to inadequate pulmonary ventilation or hypoventilation, with decrease in blood pH unless compensated by renal retention of bicarbonate. SYN: carbon dioxide a., hypercapnic a.. secondary renal tubular a. renal tubular a. that may occur as a complication of hypercalcemic states, hyperglobulinemic disorders, and in some other chronic renal conditions; a regular component of De Toni-Fanconi syndrome. starvation a. ketoacidosis resulting from lack of food intake, leading to fat catabolism to provide energy, releasing acidic ketone bodies. uncompensated a. an a. in which the pH of body fluids is subnormal, because restoration of normal acid-base balance is not possible or has not yet been achieved.

acidotic (as-i-dot′ik)
Pertaining to or indicating acidosis.

acid red 87
SYN: eosin y.

acid red 91
SYN: eosin B.

aciduria (as-i-doo′re-a)
1. Excretion of an acid urine. 2. Excretion of an abnormal amount of any specified acid. Individual types of a. are prefixed by the specific acid; e.g., aminoaciduria, ketoaciduria. [acid + G. ouron, urine] argininosuccinic a. [MIM*207900] an autosomal-recessive disorder characterized by excessive urinary excretion of argininosuccinic acid, epilepsy, ataxia, mental retardation, liver disease, and friable, tufted hair; presumed to be the consequence of a deficiency of an enzyme responsible for splitting argininosuccinic acid to arginine and fumaric acid. SYN: arginosuccinate lyase deficiency.

aciduric (as-i-doo′rik)
Pertaining to bacteria that tolerate an acid environment. [acid + L. duro, to endure]

acinar (as′i-nar)
Pertaining to the acinus. SYN: acinic.

Acinetobacter (as-i-ne′to-bak′ter)
A genus of nonmotile, aerobic bacteria (family Moraxellaceae) containing Gram-negative or -variable coccoid or short rods, or cocci, often occurring in pairs. Spores are not produced. These bacteria grow on ordinary media without the addition of serum. They are oxidase-negative and catalase-positive; carbohydrates are oxidized or not attacked at all, and arginine dihydrolase is not produced. They are a frequent cause of nosocomial infections; often resistant to many antibiotics, they can also cause severe primary infections in immunocompromised people. The type species is A. calcoaceticus. SYN: Lingelsheimia. A. calcoaceticus a species of bacteria originally found in a quinate enrichment; strains of this organism previously identified as Bacterium anitratum were found in the genitourinary tract; it is the type species of the genus A.. SYN: Lingelsheimia anitrata.

acini (as′i-ni)
Plural of acinus.

acinic (a-sin′ik)
SYN: acinar.

aciniform (a-sin′i-form)
SYN: acinous. [L. acinus, grape, + forma, shape]

acinose (as′i-nos)
SYN: acinous.

acinous (as′i-nus)
Resembling an acinus or grape-shaped structure. SYN: aciniform, acinose.

acinus, gen. and pl. acini (as′i-nus, -ni)
One of the minute grape-shaped secretory portions of an acinous gland. Some authorities use the terms a. and alveolus interchangeably, whereas others differentiate them by the constricted openings of the a. into the excretory duct. [L. berry, grape] liver a. a functional unit of the liver, comprising all of the liver parenchyma supplied by a terminal branch of the portal vein and hepatic artery; typically involves segments of two lobules lying between two terminal hepatic venules. SYN: Rappaport a.. pulmonary a. that part of the airway consisting of a respiratory bronchiole and all of its branches. SYN: primary pulmonary lobule, respiratory lobule. Rappaport a. SYN: liver a..

aclasia (a-kla′ze-a)
SYN: aclasis.

aclasis (ak′la-sis)
A state of continuity between normal and abnormal tissue. SYN: aclasia. [G. a- priv. + klasis, a breaking away, a fragment] tarsoepiphyseal a. (tar′-so-ep′i-fiz′e- al) epiphysealis hemimelica, affects ankles and knees, leading to limitation of motion. SYN: Trevor disease.

acme (ak′me)
The period of greatest intensity of any symptom, sign, or process. [G. akme, the highest point]

acne (ak′ne)
An inflammatory follicular, papular, and pustular eruption involving the pilosebaceous apparatus. SEE ALSO: a. vulgaris. [probably a corruption (or copyist's error) of G. akme, point of efflorescence]
  • a. artificialis a. produced by external irritants, such as tar (chloracne), or drugs internally administered, such as iodides or bromides. SYN: a. venenata.
  • bromide a. follicular eruption on face, trunk, and extremities, due to bromide ingestion. SEE ALSO: bromoderma.
  • a. cachecticorum a. occurring in persons who have a debilitating constitutional disease; characterized by large, soft, purulent, ulcerative, cystic, and scarred lesions.
  • a. ciliaris follicular papules and pustules on the free edges of the eyelids.
  • a. conglobata severe cystic a., characterized by cystic lesions, abscesses, communicating sinuses, and thickened, nodular scars; usually sparing the face.
  • a. cosmetica low-grade, non-inflammatory a. lesions from repeated application of comedogenic agents in cosmetics.
  • cystic a. severe a. in which the predominant lesions are follicular cysts which rupture and scar.
  • a. fulminans (ak′ne ful′mi-nanz) severe scarring a. associated with fever, polyarthralgia, crusted ulcerative lesions, weight loss, and anemia. [fulmen, fulminis, thunder, lightning]
  • a. generalis a. lesions involving the face, chest, and back.
  • halogen a. an acneform eruption caused by bromides or iodides.
  • a. hypertrophica a. vulgaris in which the lesions, on healing, leave hypertrophic scars.
  • iodide a. a follicular eruption on the face, trunk, and extremities, due to injection or ingestion of iodide in a hypersensitive individual. SEE ALSO: iododerma.
  • a. medicamentosa a. caused or exacerbated by drugs, e.g., lithium, halogens, or steroids.
  • a. necrotica miliaris SYN: a. varioliformis.
  • a. neonatorum a condition in newborn male infants, characterized by papules, pustules, and comedones on forehead and cheeks, usually resolving in a few months.
  • pomade a. a form of a. caused by repeated application of hair creams containing oils that block release of sebum from hair follicles; most commonly seen on forehead and temples in young African Americans.
  • a. punctata a. with black open comedones.
  • a. pustulosa a. vulgaris in which pustular lesions predominate.
  • a. rosacea SYN: rosacea.
  • steroid a. folliculitis or follicular hyperkeratosis resulting from topical or oral administration of steroids.
  • tar a. SYN: chloracne.
  • tropical a. a severe type of a. of the entire trunk, shoulders, upper arms, buttocks, and thighs; occurs in hot, humid climates.
  • a. varioliformis a pyogenic infection involving follicles occurring chiefly on the forehead and temples; involution of the umbilicated and crusting lesions is followed by scar formation. SYN: a. necrotica miliaris.
  • a. venenata SYN: a. artificialis.
  • a. vulgaris an eruption, predominantly of the face, upper back, and chest, composed of comedones, cysts, papules, and pustules on an inflammatory base; the condition occurs in a majority of people during puberty and adolescence, due to androgenic stimulation of sebum secretion, with plugging of follicles by keratinization, associated with proliferation of Propionibacterium acnes. Follicular suppuration may lead to scarring. Topical treatments include tretinoin, benzoyl peroxide, and antibiotics. Sunlight, systemic antibiotics, and oral 13-cis-retinoic acid (except in pregnancy) are also effective. SEE ALSO: a..

acneform (ak′ne-form)
Resembling acne. SYN: acneiform.

acneiform (ak-ne′i-form)
SYN: acneform.

acnemia, aknemia (ak-ne′me-a)
1. Congenital absence of legs. 2. Atrophy of the muscles of the calves of the legs. [G. a- priv. + kneme, leg]

ACNM
Abbreviation for American College of Nuclear Medicine.

ACNP
Abbreviation for American College of Nuclear Physicians.

acokanthera (ak-o-kan′ther-a)
Juice from the leaves and stems of A. ouabaio (family Apocynaceae), a South African arrow poison containing ouabain. [G. akoke, a point, + antheros, blooming]

acolous (ak′o-lus)
Without limbs. [G. a- priv. + kolon, limb]

aconitase (a-kon′i-tas)
SYN: aconitate hydratase.

aconitate hydratase (a-kon′i-tat)
An iron-containing enzyme catalyzing the dehydration of citric acid to cis-aconitic acid, a reaction of significance in the tricarboxylic acid cycle. SYN: aconitase.

aconite (ak′o-nit)
The dried root of Aconitum napellus (family Ranunculaceae), monkshood or wolfsbane; a powerful and rapid-acting poison formerly used as an antipyretic, diuretic, diaphoretic, anodyne, cardiac and respiratory depressant, and externally as an analgesic.

aconitine (a-kon′i-ten)
The exceedingly poisonous active principle (diterpene alkaloid) of Aconitum sp. and Delphinium sp., formerly used as a cardiac sedative and applied externally for neuralgia.

acorea (a-ko′re-a)
Congenital absence of the pupil of the eye. [G. a- priv. + kore, pupil]

Acosta
Joseph (José) de, Spanish Jesuit missionary, 1539–1600. See A. disease.

acoustic (a-koos′tik)
Pertaining to sound, e.g., a. meatus, a. nerve. [Gr. akoustikos]

acousticophobia (a-koos′ti-ko-fo′be-a)
Morbid fear of sounds. [G. akoustikos, acoustic, + phobos, fear]

acoustics (a-koos′tiks)
The science concerned with sound. [G. akoustikos, relating to sound]

ACP
Abbreviation for acyl carrier protein; American College of Physicians.

ACP-acetyltransferase
Enzyme transferring acetyl from acetyl-CoA to ACP and releasing CoA to begin fatty acid synthesis. SYN: acetyl transacylase.

ACP-malonyltransferase
An enzyme transferring malonyl from malonyl-CoA to ACP and releasing free CoA; a key step in fatty acid synthesis. SYN: malonyl transacylase.

ACPS
Abbreviation for acrocephalosyndactyly.

acquired (a-kwird′)
Denoting a disease, predisposition, abnormality, that is not inherited. [L. ac-quiro (adq-), to obtain, fr. quaero, to seek]

acquisition (ak-wi-zish′un)
In psychology, the empiric demonstration of an increase in the strength of the conditioned response in successive trials of pairing the conditioned and unconditioned stimuli. gradient-recalled a. in the steady state a type of gradient echo sequence with free induction decay sampling in magnetic resonance imaging; also called “fast imaging with steady-state precession.” This family of sequences is faster than spin echo techniques, and is used for magnetic resonance angiography and cardiac imaging.

ACR
Abbreviation for American College of Radiology.

acral (ak′ral)
Relating to or affecting the peripheral parts, e.g., limbs, fingers, ears, etc. [G. akron, extremity]

Acrania (a-kra′ne-a)
A group of the phylum Chordata whose members possess a notochord, gill slits, and nerve cord but no vertebrae, ribs, or skull; e.g., Amphioxus, tunicates, and acorn worms. [G. a- priv. + kranion, skull]

acrania (a-kra′ne-a)
Complete or partial absence of a skull; associated with anencephaly. [G. a- priv. + kranion, skull]

acranial (a-kra′ne-al)
Having no cranium; relating to acrania or an acranius.

acranius
A malformed fetus exhibiting acrania.

Acrel
Olaf, Swedish surgeon, 1717–1806. See A. ganglion.

Acremonium (ak-re-mo′ne-um)
A genus of fungi (family Moniliaceae, order Moniliales) that causes eumycotic mycetoma; three species, A. falciforme, A. kiliense, and A. recifei, produce whitish to yellow grains in the tissues. Produces keratomycosis, occasionally other infections, and the antibiotic cephalosporin.

acribometer (ak-ri-bom′e-ter)
An instrument for measuring very minute objects. [G. akribes, exact, + metron, measure]

acrid (ak′rid)
Sharp, pungent, biting, or irritating. [L. acer (acr-), pungent]

acridine (ak′ri-den)
10-Azaanthracene;a dye, dye intermediate, and antiseptic precursor (9-aminoacridine, acriflavine, proflavine hemisulfate) derived from coal tar and irritating to skin and mucous membranes. SYN: dibenzopyridine. tetramethyl a. SYN: a. orange.

acridine orange [C.I. 46005]
3,6-bis(dimethylamino)acridine hydrochloride;a basic fluorescent dye useful as a metachromatic stain for nucleic acids; also used in screening cervical smears for abnormal and malignant cells, where unusual amounts of DNA and RNA occur during proliferation and in tumors (DNA fluoresces yellow to green; RNA fluoresces orange to red). SYN: tetramethyl acridine.

acridine yellow
A faintly yellow solution with strong bluish-violet fluorescence; used as a topical antiseptic and as a fluorescent stain in histology. SYN: 5-aminoacridine hydrochloride, 9-aminoacridine hydrochloride.

acriflavine (ak-ri-fla′vin) [C.I. 46000]
An acridine dye, a mixture of 3,6-diamino-10-methylacridinium chloride and 3,6-diaminoacridine; formerly used as a topical and urinary antiseptic, and used as one of Kasten fluorescent Schiff reagents to reveal polysaccharides and DNA.

acrimonia (ak-ri-mo′ne-a)
In ancient humoral pathology, a sharp, pungent, disease-provoking humor. [L. pungency]

acrimony (ak′ri-mo-ne)
The quality of being intensely irritant, biting, or pungent. [L. acrimonia, pungency]

acrinol (ak′ri-nol)
SYN: ethacridine lactate.

acrisorcin (ak-ri-sor′sin)
A synthetic topical antifungal agent.

acritical (a-krit′i-kal, a-)
Rarely used term for: 1. Not critical; marked by no crisis; denoting diseases terminating by lysis. 2. Indeterminate, especially concerning prognosis. [G. a- priv. + kritikos, critical]

acro-
Combining form meaning: 1. Extremity, tip, end, peak, topmost. 2. Extreme. [G. akron, highest point, extremity; akros, topmost, outermost, inmost, extreme, tip]

acroagnosis (ak′ro-ag-no′sis)
Loss or impairment of the sensory recognition of a limb. Absence of acrognosis.

acroanesthesia (ak′ro-an-es-the′ze-a)
Anesthesia of one or more of the extremities. [acro- + G. an- priv. + aisthesis sensation]

acroarthritis (ak-ro-arth-ri′tis)
Inflammation of the joints of the hands or feet. [acro- + G. arthron, joint, + -itis]

acroasphyxia (ak′ro-as-fik′se-a)
Impaired digital circulation, possibly a mild form of Raynaud disease, marked by a purplish or waxy white color of the fingers, with subnormal local temperature and paresthesia. SYN: dead fingers, waxy fingers. [acro- + G. asphyxia, stoppage of the pulse]

acroataxia (ak′ro-a-tak′se-a)
Ataxia affecting the distal portion of the extremities, i.e., hands and fingers, feet, and toes. Cf.:proximoataxia. [acro- + ataxia]

acroblast (ak′ro-blast)
Component of the developing spermatid composed of numerous Golgi elements; it contains the proacrosomal granules. [acro- + G. blastos, germ]

acrobrachycephaly (ak′ro-brak-i-sef′a-le)
Type of craniosynostosis with premature closure of the coronal suture, resulting in abnormally short anteroposterior diameter of the skull. [acro- + G. brachys, short, + kephale, head]

acrocentric (ak-ro-sen′trik)
Having the centromere close to one end; said of normal chromosomes 13–15 and 21–22. [acro- + G. kentron, center]

acrocephalia (ak-ro-se-fa′le-a)
SYN: oxycephaly.

acrocephalic (ak-ro-se-fal′ik)
SYN: oxycephalic.

acrocephalopolysyndactyly (ak′ro-sef′a-lo-pol′e-sin-dak′ti-le)
A group of congenital syndromes characterized by abnormal skull shape due to craniosynostosis, brachydactyly, syndactyly, and preaxial polydactyly of hands and/or feet; mental retardation is a variable feature. There are several autosomal recessive syndromes [MIM*201000, MIM*201020, and MIM*272350] and one autosomal dominant form [MIM*101600]. A former classification of a., type I to type IV, is now considered obsolete.

acrocephalosyndactyly (ACPS) (ak′ro-sef′a-lo-sin-dak′ti-le)
A group of congenital syndromes characterized by craniosynostosis with abnormal head shape and cutaneous and/or bony syndactyly. There are several types with most types inherited as autosomal dominant. The phenotypes of types II and IV are not well defined. [acrocephaly + G. syn, together, + daktylos, finger] type I a. SYN: Apert syndrome. type II a. SYN: Vogt cephalodactyly. type III a. SYN: Saethre-Chotzen syndrome. type V a. SYN: Pfeiffer syndrome.

acrocephalous (ak-ro-sef′a-lus)
SYN: oxycephalic.

acrocephaly (ak′ro-sef′a-le)
SYN: oxycephaly. [acro- + G. kephale, head]

acrochordon (ak-ro-kor′don)
SYN: skin tag. [acro- + G. chorde, cord]

acrocinesia, acrocinesis (ak′ro-si-ne′ze-a, -e′sis)
Excessive movement. SYN: acrokinesia. [acro- + G. kinesis, movement]

acrocontracture (ak′ro-kon-trak′choor)
Contracture of the joints of the hands or feet.

acrocyanosis (ak′ro-si-a-no′sis)
A circulatory disorder in which the hands, and less commonly the feet, are persistently cold and blue; some forms are related to Raynaud phenomenon. SYN: Crocq disease, Raynaud sign. [acro- + G. kyanos, blue, + -osis, condition]

acrocyanotic (ak′ro-si-a-not′ik)
Characterized by acrocyanosis.

acrodermatitis (ak′ro-der-ma-ti′tis)
Inflammation of the skin of the extremities. [acro- + G. derma, skin, + -itis, inflammation] a. chronica atrophicans a gradually progressive late skin manifestation of Lyme disease, appearing first on the feet, hands, elbows or knees, and composed of indurated, erythematous plaques that become atrophic, giving a tissue-paper appearance of the involved sites. a. continua SYN: pustulosis palmaris et plantaris. a. enteropathica [MIM*201100] a progressive hereditary defect of zinc metabolism in young children (onset 3 weeks to 18 months), often manifests first as a blistering, oozing, and crusting eruption on an extremity or around one of the orifices of the body, followed by loss of hair and diarrhea or other gastrointestinal disturbances; relieved by lifelong oral zinc supplementation; autosomal recessive trait. papular a. of childhood SYN: Gianotti-Crosti syndrome. a. perstans SYN: pustulosis palmaris et plantaris.

acrodermatosis (ak′ro-der-ma-to′sis)
Any cutaneous affection involving the more distal portions of the extremities. [acro- + G. derma, skin, + -osis, condition]

acrodont (ak′ro-dont)
Tooth attachment in some lower vertebrates (mainly fish) in which the teeth rest on the edge of the jaw bone rather than in sockets or alveoli. [acro- + G. odous, tooth]

acrodynia (ak-ro-din′e-a)
1. Pain in peripheral or acral parts of the body. 2. A syndrome caused almost exclusively in the past by mercury poisoning: in children, characterized by erythema of the extremities, chest, and nose, gastrointestinal symptoms and by polyneuritis (in Japan); in adults, characterized by anorexia, photophobia, sweating, and tachycardia. SYN: acrodynic erythema, dermatopolyneuritis, erythredema, Feer disease, pink disease. [acro- + G. odyne, pain]

acrodysesthesia (ak′ro-dis-es-the′ze-a)
Abnormal and unpleasant sensations in the peripheral portions of the extremities. [acro- + dysesthesia]

acrodysostosis (ak′ro-dis-os-to′sis) [MIM*101800]
A disorder in which the hands and feet are short with stubby fingers and toes. Growth retardation is progressive. Mental retardation and marked nasal hypoplasia are also present; autosomal dominant inheritance. [acro- + dysostosis]

acroesthesia (ak′ro-es-the′ze-a)
1. An extreme degree of hyperesthesia. 2. Hyperesthesia of one or more of the extremities. [acro- + G. aisthesis, sensation]

acrogenous (ak-roj′e-nus)
Denoting conida of fungi produced by the conidiogenous cell at the tip of a conidiophore. [acro- + G. genos, birth]

acrogeria (ak-ro-jer′e-a) [MIM*201200]
Reduction or loss of subcutaneous fat and collagen of the hands and feet, giving the appearance of premature aging. [acro- + G. geron, old]

acrognosis (ak-rog-no′sis)
Cenesthesia, or normal sensory perception, of the extremities. [acro- + G. gnosis, knowledge]

acrohyperhidrosis (ak′ro-hi′per-hi-dro′sis)
Hyperhidrosis of the hands and feet.

acrohyperkeratosis


acrokeratoelastoidosis (ak′ro-ker′a-to-e-las-toy-do′sis) [MIM*101850]
An autosomal dominant papular keratosis of the palms and soles, with disorganization of dermal elastic fibers; a similar, but acquired, condition may result from actinic damage of the hands. SEE ALSO: keratoelastoidosis. SYN: focal acrohyperkeratosis, type III punctate palmoplantar keratoderma. [acro + G. keras, horn, + elastos, beaten, + eidos, resemblance, + -osis, condition]

acrokeratosis (ak′ro-ker-a-to′sis)
Overgrowth of the horny layer of the skin, usually nodular configurations, of the dorsum of the fingers and toes, and occasionally on the rim of the ear and tip of the nose. [acro- + G. keras, horn, + -osis, condition] paraneoplastic a. a rare nail dystrophy with acral erythema and scaling associated with upper respiratory or upper alimentary cancer. SYN: Bazex syndrome.

acrokinesia (ak′ro-ki-ne′ze-a)
SYN: acrocinesia.

acromegalia (ak′ro-me-ga′le-a)
SYN: acromegaly.

acromegalic (ak′ro-me-gal′ik)
Pertaining to or characterized by acromegaly.

acromegalogigantism (ak′ro-meg′a-lo-ji′gan-tizm)
Gigantism in which the facial features, disproportionate enlargement of the extremities, and other signs of acromegaly are prominent. [acro- + G. megas, great, + gigas, giant]

acromegaloidism (ak-ro-meg′a-loyd-izm)
Rarely used term for a condition in which body proportions resemble those of acromegaly.

acromegaly (ak-ro-meg′a-le)
A disorder marked by progressive enlargement of peripheral parts of the body, especially the head, face, hands, and feet, due to excessive secretion of somatotropin; organomegaly and metabolic disorders occur; diabetes mellitus may develop. SYN: acromegalia. [acro- + G. megas, large]

acromelalgia (ak-ro-mel-al′je-a)
See erythromelalgia. [acro- + G. melos, limb, + algos, pain]

acromelia (ak-ro-mez-o-me′le-a)
SYN: acromesomelia.

acromelic (ak-ro-mel′ik)
Affecting the terminal part of a limb. [acro- + G. melos, limb]

acromesomelia (ak-ro-me-so-me′le-a)
SYN: acromesomelic dwarfism. SYN: acromelia. [acro- + G. melos, limb, + ia, condition]

acrometagenesis (ak′ro-met-a-jen′e-sis)
Abnormal growth of the extremities resulting in malformation. [acro- + G. meta, beyond, + genesis, origin]

acromial (a-kro′me-al)
Relating to the acromion.

acromicria (ak-ro-mik′re-a, ak-ro-mi′kre-a)
The antithesis of acromegaly; a condition in which the bones of the face and extremities are small and delicate; possibly due to a deficiency of somatotropin. [acro- + G. mikros, small]

acromioclavicular (a-kro′me-o-kla-vik′u-lar)
Relating to the acromion and the clavicle; denoting the articulation and ligaments between the clavicle and the acromion of the scapula. SYN: scapuloclavicular (1) .

acromiocoracoid (a-kro-me-o-kor′a-koyd)
SYN: coracoacromial.

acromiohumeral (a-kro′me-o-hu′mer-al)
Relating to the acromion and the humerus.

acromion (a-kro′me-on) [TA]
The lateral end of the spine of the scapula which projects as a broad flattened process overhanging the glenoid fossa; it articulates with the clavicle and gives attachment to part of the deltoid and trapezius muscles. Its lateral border is a palpable landmark (“the point of the shoulder”). SYN: acromial process. [G. akromion, fr. akron, tip, + omos, shoulder]

acromioplasty (a-kro′me-o-plas-ty)
A surgical reshaping of the acromion, frequently performed to remedy compression of the supraspinatus portion of the rotator cuff of the shoulder joint between the acromion and the greater tubercle of the humerus.

acromioscapular (a-kro′me-o-skap′u-lar)
Relating to both the acromion and body of the scapula.

acromiothoracic (a-kro′me-o-tho-ras′ik)
SYN: thoracoacromial.

acromphalus (ak-rom′fal-us)
Abnormal projection of the umbilicus. [acro- + G. omphalos, umbilicus]

acromyotonia (ak′ro-mi-o-to′ne-a)
Myotonia affecting the extremities only, resulting in spastic deformity of the hand or foot. SYN: acromyotonus. [acro- + G. mys, muscle, + tonos, tension]

acromyotonus (ak-ro-mi-ot′o-nus)
SYN: acromyotonia.

acroosteolysis (ak′ro-os-te-ol′i-sis) [MIM*102500]
Congenital condition manifested by palmar and plantar ulcerating lesions with osteolysis involving distal phalanges of the fingers and toes. Acquired acro-osteolysis has been reported in workers exposed to vinyl chloride. There is an autosomal disorder, Cheney syndrome [MIM*102500], in which this finding is combined with wormian bones, hypoplasia of the mandibular rami, and basilar osteoporosis. SEE ALSO: Cheney syndrome. [acro- + G. osteon, bone, + lysis, loosening]

acropachy (ak′ro-pak-e, a-krop′a-ke) [MIM*119900]
SYN: hereditary clubbing. [acro- + G. pachys, thick]

acropachyderma (ak′ro-pak-i-der′ma)
SYN: pachydermoperiostosis. [acro- + G. pachys, thick, + derma, skin]

acroparesthesia (ak′ro-par-es-thes′e-a)
1. Paresthesia of one or more of the extremities. 2. Nocturnal paresthesia involving the hands, most often of middle-aged women; formerly attributed to a lesion in the thoracic outlet, but now known to be a classic symptom of carpal tunnel syndrome. [acro- + paresthesia]

acropetal (a-krop′e-tal)
1. In a direction toward the summit. 2. Produced successively toward the apex, with the youngest conidium formed at the tip and the oldest at the base of a chain of conidia; pertaining to asexual spore production in fungi by successive budding of the distal spore in a spore chain. [acro- + L. peto, to seek]

acrophobia (ak-ro-fo′be-a)
Morbid fear of heights. [acro- + G. phobos, fear]

acropigmentation (ak′ro-pig-men-ta′shun)
Punctate and reticulate hyperpigmentation of the dorsal surfaces of the fingers and toes beginning in early childhood and usually increasing with age; more common in Asian persons of dark complexion.

acropleurogenous (ak′ro-ploo-roj′e-nus)
Denoting spores developing at the tip and along the sides of fungal hyphae.

acropustulosis (ak′ro-pus-tu-lo′sis)
Pustular eruptions of the hands and feet, often a form of psoriasis. [acro- + pustulosis] infantile a. a cyclically recurrent vesicopustular and crusting pruritic eruption, usually in black children, appearing soon after birth to 10 months; remission occurs at about 2 years of age.

acroscleroderma (ak′ro-skler-o-der′ma)
SYN: acrosclerosis. [acro- + G. skleros, hard, + derma, skin]

acrosclerosis (ak′ro-skle-ro′sis)
Stiffness and tightness of the skin of the fingers, with atrophy of the soft tissue and osteoporosis of the distal phalanges of the hands and feet; a limited form of progressive systemic sclerosis occurring with Raynaud phenomenon and scleroderma of the forearms. See CREST syndrome. SYN: acroscleroderma, sclerodactyly, sclerodactylia.

acrosin (ak′ro-sin)
A serine proteinase in spermatozoa similar in specificity to trypsin.

acrosome (ak′ro-som)
A caplike organelle or saccule derived from the golgi that surrounds the anterior two-thirds of the nucleus of a sperm cell. Within this cap are enzymes that are thought to facilitate entry of the sperm through the zona pellucida. [acro- + G. soma, body]

acrosomin (ak-ro-so′min)
A lipoglycoprotein complex present in the acrosomal cap.

acrospiroma (ak′ro-spi-ro′ma)
A tumor of the distal dermal segment of a sweat gland. [scro- + G. speira, coil, + -oma, tumor] eccrine a. SYN: clear cell hidradenoma.

acroteric (ak-ro-ter′ik)
Relating to the extreme peripheral or apical parts, such as the tips of fingers and toes, the end of the nose. [G. akroterion, the topmost point]

Acrotheca (ak-ro-the′ka)
Former name for species now placed in the genus Rhinocladiella or Fonsecaea. [see a.]

acrotheca (ak-ro-the′ka)
In fungi, a type of spore formation characteristic of the genus Fonsecaea, in which conidia are formed along the ends and sides of irregular club-shaped conidiophores. [acro- + G. theke, box, case]

acrotic (a-krot′ik)
1. Marked by great weakness or absence of the pulse; pulseless. [G. a- priv. + krotos, a striking] 2. Obsolete term relating to the surface of the body, especially the cutaneous glands. [G. akrotes, extremity]

acrotism (ak′ro-tizm)
Absence or imperceptibility of the pulse. [G. a- priv. + krotos, a striking]

acrotrophodynia (ak′ro-trof′o-din′e-a)
Pain, paresthesia, sensory loss, and trophic changes affecting the distal extremities, usually the feet, that can follow prolonged exposure of the limbs to cold and moisture. [acro- + G. trophe, nourishment, + odyne, pain]

acrotrophoneurosis (ak′ro-trof′o-noo-ro′sis)
Trophoneurosis of one or more of the extremities. [acro- + G. trophe, nourishment, + neuron, nerve, + -osis, condition]

acrylate (a′kril-at)
A salt or ester of acrylic acid.

acrylic (a-kril′ik)
Denoting certain synthetic plastic resins derived from a. acid. SEE ALSO: a. resin.

acrylic acids
A series of unsaturated aliphatic acids of the general formula R&dbond;CH&cbond;COOH; the prototype, acrylic acid (R = CH2) or 2-propenoic acid, is derived from propionic acid by reduction or from glycerol by dehydration.

ACT
Abbreviation for activated clotting time.

ACTH
Abbreviation for adrenocorticotropic hormone. big A. a form of A., produced by certain tumors, which is a larger and more acidic peptide molecule than little A., but is not immunochemically distinguishable from it and does not exert any of the biologic effects characteristic of A.; proteolytic digestion of big A. yields hormonally active little A CTH. little A. a term coined to denote the conventional A. molecule when contrasted with big A..

actin (ak′tin)
One of the protein components into which actomyosin can be split; it can exist in a fibrous form (F-a.) or a globular form (G-a.). F-a. the association of G-a. subunits into a fibrous (F) protein caused by an increase in salt concentration; the conversion of G-a. to F-a. is catalyzed by small concentrations of magnesium ion, is reversible, and is accompanied by the conversion of the bound ATP molecule to ADP and the conversion of one reactive -thiol group to an unreactive form. G-a. the globular (G) subunits of the a. molecule, having a molecular weight 42 kd and containing one molecule of ATP; it is soluble in dilute salt, polymerizing to F-a. when the ionic strength is increased.

acting out
An overt act or set of actions that provides an emotional outlet for the expression of emotional conflicts (usually unconscious).

actinic (ak-tin′ik)
Relating to the chemically active rays of the electromagnetic spectrum. [G. aktis (aktin-), a ray]

actinides (ak′tin-idz)
Those elements with atomic numbers 89 to 103, corresponding to the lanthanides in the Periodic Table. SYN: actinide elements. [actinium, first element of the series]

α-actinin (ak-tin′in)
An F-actin binding protein in vertebrate cells that cross-links actin filaments into regular parallel arrays. It is found in both the Z line and the I band.

actinium (Ac) (ak-tin′e-um)
An element, atomic no. 89, atomic wt. 227.05; it possesses no stable isotopes and exists in nature only as a disintegration product of uranium and thorium. [G. aktis, a ray]

actino-
Combining form meaning a ray, as of light; applied to any form of radiation or to any structure with radiating parts. SEE ALSO: radio-. [G. aktis, aktinos, a ray of light, a beam.]

actinobacillosis (ak′tin-o-bas-i-lo′sis)
A disease of cattle and swine, occasionally reported in humans, caused by the bacterium Actinobacillus lignieresii. It affects the soft tissues, often the tongue and cervical lymph nodes, where granulomatous swellings are formed that eventually break down to form abscesses.

Actinobacillus (ak′tin-o-ba-sil′lus)
A genus of very small, nonmotile, nonsporeforming, aerobic, facultatively anaerobic bacteria containing Gram-negative rods interspersed with coccal elements. The metabolism of these bacteria is fermentative. They are pathogenic to animals. The type species is A. lignieresii. [actino- + L. bacillus, a little rod] A. actinomycetemcomitans a species of doubtful taxonomic position; frequently associated with human periodontal disease as well as subacute and chronic endocarditis; occurs with actinomycetes in actinomycotic lesions. SYN: Haemophilus actinomycetemcomitans. A. lignieresii a species producing infections of the upper alimentary tract and mouth in cattle and swine (actinobacillosis) and suppurative lesions in the skin and lungs of sheep; it is the type species of its genus.

actinohematin (ak′ti-no-he′ma-tin)
A red respiratory pigment found in certain forms of Actinia (sea anemones). [actino- + G. haima, blood]

Actinomadura (ak′ti-no-ma-du′-ra)
A genus of aerobic Gram-positive, branching, nonacidfast filamentous bacteria; it may form aerial hyphae and may contain chains of up to 15 spores. [actino- + Madura, India] A. africana a bacterial species found in cases of mycetoma of the foot in Africa. A. latina a species of bacteria associated with mycetoma in South America. A. madurae an aerobic actinomycete; a cause of actinomycetoma. A. pelliertieri A. latina.

actinomycelial (ak′ti-no-mi-se′le-al)
Relating to the mycelium-like filaments of the Actinomycetales.

Actinomyces (ak′ti-no-mi′sez)
A genus of slow-growing, nonmotile, nonsporeforming, anaerobic to facultatively anaerobic bacteria (family Actinomycetaceae) containing Gram-positive, irregularly staining filaments; diphtheroid cells may be predominant. They exhibit true branching while forming mycelial type colonies. Most of the species produce a filamentous microcolony. The metabolism of these chemoheterotrophs is fermentative; the products of glucose fermentation include acetic, formic, lactic, and succinic acids but not propionic acid. A. may have characteristic sulfur granules in purulent drainage. These organisms are pathogenic for humans and other animals and can cause chronic suppurative infection in humans. Over 16 species have been described; type species is A. bovis. [actino- + G. mykes, fungus] A. bovis a species of bacteria causing actinomycosis in cattle; infection in humans is not established; it is the type species of its genus. A. israelii the most common species of a. causing human actinomycosis and, occasionally, infections in cattle. A. naeslundii a species whose natural habitat is the oral cavity; human infections occur and it produces periodontal destruction in some species of animals. A. odontolyticus a species whose normal habitat is the human oral cavity; it has been isolated from deep dental caries. A. viscosus a species that has been isolated from the oral cavity of humans and some species of other animals; it produces periodontal disease in animals and has been isolated from human dental calculus and root surface caries.

Actinomycetaceae (ak′ti-no-mi′se-ta′se-e)
A family of nonsporeforming, nonmotile, ordinarily facultatively anaerobic (some species are aerobic and others are anaerobic) bacteria (order Actinomycetales) containing Gram-positive, nonacidfast, predominantly diphtheroid cells which tend to form branched filaments in tissue or in some stages of cultural development; the filaments readily fragment, producing diphtheroid or coccoid forms. The metabolism of these chemoheterotrophic bacteria is fermentative. This family contains the genera Actinomyces (type genus), Arachnia, Bacterionema, Bifidobacterium, and Rothia.

Actinomycetales (ak′ti-no-mi′se-ta′lez)
An order of bacteria consisting of moldlike, rod-shaped, clubbed or filamentous forms with decided tendency to true branching, without endospores, but sometimes developing conidia; it includes the families Mycobacteriaceae, Actinomycetaceae, and Nocardiaceae.

actinomycetes (ak′ti-no-mi-se′tez)
A term used to refer to members of the genus Actinomyces; sometimes improperly used to refer to any member of the family Actinomycetaceae or order Actinomycetales.

actinomycetoma (ak′tin-o-mi-set-o′ma)
Mycetoma caused by higher bacteria. Cf.:eumycetoma.

actinomycin (ak′tin-o-mi′sin)
A group of peptide antibiotic agents, isolated from several species of Streptomyces (originally Actinomyces), that are active against Gram-positive bacteria, fungi, and neoplasms. Actinomycins are chromopeptides, most containing the chromophore actinocin, and are derivatives of phenoxazine that differ in their amino acids and their sequence in the peptide chains; they form complexes with DNA and therefore inhibit RNA synthesis, primarily the ribosomal type. a. A the first of the actinomycins isolated in crystalline form. a. C SYN: cactinomycin. a. D SYN: dactinomycin. a. F1 KS4;produced by a. C-elaborating strains of Streptomyces chrysomallus; used as an antineoplastic agent.

actinomycosis (ak′ti-no-mi-ko′sis)
A disease primarily of cattle and humans caused by the bacterium Actinomyces bovis in cattle and by A. israelii and Arachnia propionica in humans. These actinomycetes are part of the normal bacterial flora of the mouth and pharynx, but when introduced into tissue they may produce chronic destructive abscesses or granulomas that eventually discharge a viscid pus containing minute yellowish granules (sulfur granules). In humans, the disease commonly affects the cervicofacial area, abdomen, or thorax; in cattle, the lesion is commonly found in the mandible. SYN: actinophytosis (1) , lumpy jaw. [actino- + G. mykes, fungus, + -osis, condition]

actinomycotic (ak′ti-no-mi-kot′ik)
Relating to actinomycosis.

Actinomyxidia (ak′ti-no-mik-sid′e-a)
A sporozoan order having a double cellular envelope, three polar capsules, and eight spores; parasitic chiefly in segmented worms, such as the common earthworm. [actino- + G. myxa, mucus]

actinophage (ak-tin′o-faj)
A virus specific for actinomycetes. [actino(myces) + G. phago, to eat]

actinophytosis (ak′ti-no-fi-to′sis)
1. SYN: actinomycosis. 2. SYN: botryomycosis.

Actinopoda (ak-ti-nop′o-da)
A class of Sarcodina having slender pseudopodia with a central axial filament. [actino- + G. pous, foot]

actinosin (ak-tin′o-sin)
A phenoxazone derivative that is the chromophore of the actinomycins.

actinotherapy (ak′ti-no-thar′a-pe)
In dermatology, sunlight or ultraviolet light therapy.

action (ak′shun)
1. The performance of any of the vital functions, the manner of such performance, or the result of the same. 2. The exertion of any force or power, physical, chemical, or mental. [L. actio, from ago, pp. actus, to do] ball valve a. intermittent blockage of a tube or outlet of a cavity by some object or material that permits passage in one direction but not in the other. calorigenic a. increase of heat production of the body, as by the thyroid hormone. SYN: thermogenic a.. cumulative a. SYN: cumulative effect. salt a. any physicochemical effect produced by hypertonic concentrations of osmotically active electrolytes. sparing a. the manner in which a nonessential nutritive component, by its presence in the diet, lowers the dietary requirement for an essential component; thus, nonessential l-cysteine spares essential l-methionine and nonessential l-tyrosine spares essential l-phenylalanine. SYN: sparing phenomenon. specific a. the a. of a drug or a method of treatment which has a direct and especially curative effect upon a disease, e.g., the a. of vitamin B12 in pernicious anemia. specific dynamic a. (SDA) increase of heat production caused by the ingestion of food, especially of protein. thermogenic a. SYN: calorigenic a..

activate (ak′ti-vat)
1. To render active. 2. To make radioactive.

activation (ak-ti-va′shun)
1. The act of rendering active. 2. An increase in the energy content of an atom or molecule, through the raising of temperature, absorption of light photons, etc., which renders that atom or molecule more reactive. 3. Techniques of stimulating the brain by light, sound, electricity, or chemical agents, in order to elicit abnormal activity in the electroencephalogram. 4. Stimulation of peripheral nerve fibers to the point that action potentials are initiated. 5. Stimulation of cell division in an ovum by fertilization or by artificial means. 6. The act of making radioactive. SEE ALSO: cross-section. amino acid a. the formation of the amino acyl adenylate derivative ( E.G., during protein biosynthesis). EEG a. the low voltage, fast pattern of attentive wakefulness. feedback a. inhibitory or antiinhibitory a. on an enzyme by an end product of a biochemical pathway in which that enzyme plays a part. For example, the a. of factors VIII and V by thrombin during blood clotting. feed-forward a. the a. or stimulation of an enzyme by a precursor of the substrate of that enzyme. gene a. the process of a. of a gene so that it is expressed at a particular time. This process is crucial in growth and development.

activator (ak′ti-va-tor)
1. A substance that renders another substance, or catalyst, active, or that accelerates a process or reaction. 2. The fragment, produced by chemical cleavage of a proactivator, that induces the enzymic activity of another substance. 3. An apparatus for making substances radioactive; e.g., neutron generator, cyclotron. 4. A removable type of myofunctional orthodontic appliance that acts as a passive transmitter of force, produced by the function of the activated muscles, to the teeth and alveolar process that are in contact with it. 5. a protein that binds to a DNA sequence before RNA polymerase transcription. catabolite gene a. (CGA) SYN: catabolite (gene) a. protein. plasminogen a. a proteinase converting plasminogen to plasmin by cleavage of a single (usually Arg-Val) bond in the former. SYN: urokinase. polyclonal a. (pol-e-klo′nal) a substance that will activate T cells, B cells, or both regardless of their specificities. tissue plasminogen a. (TPA, tPA) 1. a naturally occurring thrombolytic serine protease that catalyzes the conversion of plasminogen to plasmin; 2. a genetically engineered protein used as a thrombolytic agent in myocardial infarction, stroke, and peripheral vascular thrombosis.TPA is a single-chain glycoprotein with a molecular weight of about 70 kD. Produced by endothelial cells at sites of vascular injury, it modulates thrombogenesis by converting fibrin-bound plasminogen to plasmin, cleaving the arginine-valine bond in the 560–561 position of plasminogen. As a result, fibrin strands in a clot are chemically degraded and platelet adhesion and aggregation are inhibited. TPA has little effect on plasminogen in the absence of fibrin, and its release does not significantly reduce systemic concentrations of fibrinogen. Alteplase, a synthetic TPA produced by recombinant DNA technology, improves outcome when administered intravenously in acute myocardial infarction and in selected cases of stroke and peripheral ischemia due to thrombosis. It has a circulating half-life of only 4–6 minutes, but persists in clots up to 7 hours. see thrombolytic therapy.

activin (ak′ti-vin)
Placental hormone that reaches maximum levels in maternal serum during labor. [active + -in]

activity (ak-tiv′i-te)
1. In electroencephalography, the presence of neurogenic electrical energy. 2. In physical chemistry, an ideal concentration for which the law of mass action will apply perfectly; the ratio of the a. to the true concentration is the a. coefficient (γ), which becomes 1.00 at infinite dilution. 3. For enzymes, the amount of substrate consumed (or product formed) in a given time under given conditions; turnover number. 4. The number of nuclear transformations (disintegrations) in a given quantity of a material per unit time. Units: curie (Ci), millicurie (mCi), becquerel (Bq), megabecquerel (MBq). SEE ALSO: radioactivity. blocking a. repression or elimination of electrical a. in the brain by the arrival of a sensory stimulus. insulinlike a. (ILA) a measure of substances, usually in plasma, that exert biologic effects similar to those of insulin in various bioassays; sometimes used as a measure of plasma insulin concentrations; always gives higher values than immunochemical techniques for the measurement of insulin. intrinsic sympathomimetic a. (ISA) the property of a drug that causes activation of adrenergic receptors so as to produce effects similar to stimulation of the sympathetic nervous system. nonsuppressible insulinlike a. (NSILA) plasma insulinlike a. not suppressed by antibodies to insulin and mostly present after pancreatectomy. Nonsuppressible insulinlike a. is mostly the action of polypeptide insulinlike growth factors IGF-I and IGF-II. optic a. the ability of a compound in solution (one possessing no plane of symmetry, usually because of the presence of one or more asymmetric carbon atoms) to rotate the plane of polarized light. plasma renin a. (PRA) estimation of renin in plasma by measuring the rate of formation of angiotensin I or II. pulseless electrical a. (PEA) SYN: electromechanical dissociation. specific a. 1. radioactivity per unit mass of the stated element or compound; 2. for an enzyme, the amount of substrate consumed (or product formed) in a given time under given conditions per milligram of protein; 3. a. per unit mass of the stated radionuclide. triggered a. one or a series of spontaneously generated heartbeats originating from an action potential that produces an after-depolarization which reaches activation threshold.

actomyosin (ak′-to-mi′o-sin)
A protein complex composed of actin and myosin; it is the essential contractile substance of muscle fiber, active with MgATP. platelet a. the contractile protein of platelets, responsible for clot retraction, platelet aggregation, and release of ADP and other biologic amines essential to platelet function. SYN: thrombosthenin.

Acuaria spiralis (ak-u-a′re-a spi-ra′lis)
A nematode parasite in the proventriculus and esophagus, and sometimes the intestine, of chickens, turkeys, pheasants, and other birds. [L. acus, needle; Mod. L. spiralis, spiral]

acuity (a-ku′i-te)
1. Sharpness, clearness, distinctness. 2. Severity. [thr. Fr., fr. L. acuo, pp. acutus, sharpen] absolute intensity threshold a. the minimal light that can be seen. resolution a. detection of a target having two or more parts, often measured by using the Snellen test types; indicated by two numbers: the first represents the distance at which an individual sees the test types (usually 6 m or 20 ft), and the second, the distance at which the test types subtend an angle of 5 min.; e.g., vision of 6/9 indicates a test distance of 6 m and recognition of symbols that subtend an angle of 5 min. at a distance of 9 m. SYN: visual a.. spatial a. detection of the shape of a test object; e.g., perceiving polygons of the same size but with different numbers of sides. stereoscopic a. the detection of differences in distance by superimposition of slightly different retinal images into a single image to the brain. Vernier a. detection of displacement of a portion of a line. visibility a. recognition of an object on a background of different character. visual a. (V) SYN: resolution a..

aculeate (a-ku′le-at)
Pointed; covered with sharp spines. [L. aculeatus, pointed, fr. acus, needle]

acumentin (ak-u-men′tin)
A neutrophil and macrophage motility protein that links to the actin molecule to control filament length.

acuminate (a-ku′mi-nat)
Pointed;tapering to a point. [L. acumino, pp. -atus, to sharpen]

acuology (ak-u-ol′o-je)
The study of the use of needles for therapeutic purposes, as in acupuncture. [L. acus, needle, + G. logos, study]

acupressure
Application of pressure in sites used for acupuncture with therapeutic intent.

acupuncture (ak-u-punk′choor)
Puncture with long, fine needles: 1. An ancient Asian system of therapy. 2. More recently, a. anesthesia or analgesia. [L. acus, needle, + puncture]

acusis (a-ku′sis)
The ability to perceive sound normally. SYN: normal hearing. [G. akousis, hearing]

acute (a-kut′)
1. Referring to a health effect, usually of rapid onset, brief, not prolonged; sometimes loosely used to mean severe. 2. Referring to exposure, brief, intense, short-term; sometimes specifically referring to brief exposure of high intensity. [L. acutus, sharp]

acyanotic (a-si-a-not′ik)
Characterized by absence of cyanosis.

acyclic (a-si′klik)
Not cyclic; denoting especially an a. compound.

acycloguanosine (a-si-klo-gwan′o-sen)
SYN: acyclovir.

acyclovir (a-si′klo-vir)
A synthetic acyclic purine nucleoside analog used as an antiviral agent in the treatment of genital herpes; the sodium salt is used for parenteral therapy. SYN: acycloguanosine.

acyl (as′il)
An organic radical derived from an organic acid by the removal of the carboxylic hydroxyl group.

acyl-ACP dehydrogenase, acyl-ACP reductase
SYN: enoyl-ACP reductase (NADPH).

acyladenylate (as′il-a-den′il-at)
A compound in which an acyl group is combined with AMP by elimination of H2O between the OHs of a carboxyl group and of the phosphate residue of AMP, usually initially in the form of ATP and eliminating inorganic pyrophosphate in the condensation.

acylation (as-i-la′shun)
Introduction of an acyl radical into an organic compound or formation of such a radical within an organic compound.

acylcarnitine (as′il-kar′ni-ten)
Condensation product of a carboxylic acid and carnitine. The transport form for a fatty acid crossing the inner mitochondrial membrane.

acyl-CoA
Condensation product of a carboxylic acid and coenzyme A; metabolic intermediate of importance, notably in the oxidation and synthesis of fat. SYN: acyl-coenzyme A. acyl-CoA dehydrogenase (NADPH) enzyme catalyzing the reversible reduction of enoyl-CoA derivatives of chain length 4–16, with NADPH as the hydrogen donor, forming acyl-CoA and NADP+. SYN: enoyl-CoA reductase. acyl-CoA synthetase 1. general term for enzymes (EC 6.2.1.x) that form acyl-CoA, now called ligases; 2. specifically, long-chain fatty acid–CoA ligase.

acyl-coenzyme A (as′il-ko-en′zim)
SYN: acyl-CoA.

1-acylglycerol-3-phosphate acyltransferase
See lysophosphatidic acid acyltransferase.

acyl-malonyl-ACP synthase
SYN: 3-oxoacyl-ACP synthase.

acylmercaptan (as′il-mer-kap′tan)
SYN: thioester.

acyltransferases (as-il-trans′fer-a-sez) [EC 2.3.x.x]
Enzymes catalyzing the transfer of an acyl group from an acyl-CoA to various acceptors. SYN: transacylases.

acystia (a-sis′te-a)
Congenital absence of the urinary bladder. [G. a- priv. + kystis, bladder]

A.D.
Abbreviation for auris dexter [L.], right ear.

ad-
Prefix denoting increase, adherence, to, toward; near; very. [L. ad, to, toward;]

-ad
In anatomical nomenclature, -ward; toward or in the direction of the part indicated by the main portion of the word. [L. ad, to]

ADA
Abbreviation for American Dental Association.

adacrya (a-dak′re-a)
Absence of tears; tearlessness. [G. a- priv. + dakryon, tear, + -ia]

adactylous (a-dak′ti-lus)
Without fingers or toes.

Adair-Koshland-Némethy-Filmer model (AKNF)
See under model.

adamantine (ad-a-man′ten)
Exceedingly hard; formerly used in reference to the enamel of the teeth. [G. adamantinos, very hard]

adamantinoma
pituitary a. SYN: craniopharyngioma.

Adamkiewicz
Albert, Polish pathologist, 1850–1921. See artery of A..

Adams
Sir William, British surgeon, 1760–1829.

Adams
Robert, Irish physician, 1791–1875. See A.-Stokes disease, Stokes-A. disease, A.-Stokes syncope, A.-Stokes syndrome, Stokes-A. syndrome, Morgagni-A.-Stokes syndrome.

Adam's apple
SYN: laryngeal prominence.

adamsite (DM) (ad′am-sit)
A vomiting agent that has been used in military training and in riot control. [Roger Adams, Am. chemist]

Adanson
Michel, French naturalist, 1727–1806. See adansonian classification.

adaptation (ad-ap-ta′shun)
1. Preferential survival of members of a species because of a phenotype that gives them an enhanced capacity to withstand the environment including the ecology. 2. An advantageous change in function or constitution of an organ or tissue to meet new conditions. 3. Adjustment of the sensitivity of the retina to light intensity. 4. A property of certain sensory receptors that modifies the response to repeated or continued stimuli at constant intensity. 5. The fitting, condensing, or contouring of a restorative material, foil, or shell to a tooth or cast so as to be in close contact. 6. The dynamic process wherein the thoughts, feelings, behavior, and biophysiologic mechanisms of the individual continually change to adjust to a constantly changing environment. SYN: adjustment (2) . 7. A homeostatic response. [L. ad-apto, pp. -atus, to adjust] dark a. the visual adjustment occurring under reduced illumination in which the retinal sensitivity to light is increased. SEE ALSO: dark-adapted eye, Purkinje shift. SYN: scotopic a.. light a. the visual adjustment occurring under increased illumination in which the retinal sensitivity to light is reduced. SEE ALSO: light-adapted eye, Purkinje shift. SYN: photopic a.. photopic a. SYN: light a.. reality a. the ability to adjust to the world as it exists. retinal a. adjustment to degree of illumination. scotopic a. SYN: dark a.. social a. adjustment to living in accordance with interpersonal, social, and cultural norms.

adapter, adaptor (a-dap′ter, -tor)
1. A connecting part, joining two pieces of apparatus. 2. A converter of electric current to a desired form.

adaptometer (ad-ap-tom′e-ter)
A device for determining the course of retinal dark adaptation and for measuring the minimum light threshold.

adaxial (ad-ak′se-al)
Toward an axis, or on one or other side of an axis.




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