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Medical Dictionary


proinsulin (pro-in′su-lin)
A single-chain precursor of insulin.

projection (pro-jek′shun)
1. A pushing out; an outgrowth or protuberance. 2. The referring of a sensation to the object producing it. 3. A defense mechanism by which a repressed complex in the individual is denied and conceived as belonging to another person, as when faults that the person tends to commit are perceived in or attributed to others. 4. The conception by the consciousness of a mental occurrence belonging to the self as of external origin. 5. Localization of visual impressions in space. 6. In neuroanatomy, the system or systems of nerve fibers by which a group of nerve cells discharges its nerve impulses (“projects”) to one or more other cell groups. 7. The image of a three-dimensional object on a plane, as in a radiograph. 8. In radiography, standardized views of parts of the body, described by body part position, the direction of the x-ray beam through the body part, or by eponym. SYN: norma (3) , salient (1) , view. [L. projectio; fr. pro- jicio, pp. -jectus, to throw before] anteroposterior p. SYN: AP p.. AP p. the alternative frontal radiographic p., used mainly in bedside or portable radiography. SYN: anteroposterior p.. apical lordotic p. SYN: backprojection. axial p. radiographic p. devised to obtain direct visualization of the base of the skull. SYN: axial view, base p., submental vertex p., submentovertical p., verticosubmental view. base p. SYN: axial p.. Caldwell p. inclined PA radiographic p. devised to permit visualization of orbital structures unobstructed by the petrous ridges. SYN: Caldwell view. cross-table lateral p. lateral p. radiography of a supine subject using a horizontal x-ray beam. enamel p. extension of enamel into furcation. erroneous p. SYN: false p.. false p. the faulty visual sensation arising secondarily to underaction of an ocular muscle. SYN: erroneous p.. Fischer p. sugars. frog-leg lateral p. a lateral p. of the femoral neck made with the thigh maximally abducted. Granger p. view, reversed half-axial view; uncommonly used PA view of the skull. half-axial p. SYN: Towne p.. Haworth p. sugars. lateral p. radiographic p. with the x-ray beam in a coronal plane. maximum intensity p. (MIP) a computerized image display method, used in MR angiography and helical computed tomography; a series of slices are combined with display of the brightest pixel on any slice at each location, and suppression of the background; simulates a p. angiogram. oblique p. any radiographic p. between frontal and lateral. occipitomental p. SYN: Waters p.. PA p. the standard frontal chest film p.; radiographic skull p. with the petrous ridge superimposed on the orbits. SYN: posteroanterior p.. posteroanterior p. SYN: PA p.. Rhese p. oblique radiographic view of the skull to show the optic foramen. Stenvers p. oblique radiographic p. of the skull devised to provide an unobstructed view of the petrous bone, bony labyrinth, internal auditory canal, and meatus. SYN: Stenvers view. submental vertex p. SYN: axial p.. submentovertical p. SYN: axial p.. Towne p. reverse tilted AP radiographic p. devised to permit demonstration of the entire occipital bone, foramen magnum, and dorsum sellae, as well as the petrous ridges. SYN: half axial view, half-axial p., Towne view. visual p. a perceptual synthesis involving visual mechanisms. Waters p. a PA radiographic view of the skull made with the orbitomeatal line at an angle of 37° from the plane of the film, to show the orbits and maxillary sinuses. SYN: occipitomental p., Waters view.

Prokaryotae (pro-kar-e-o′te)
A superkingdom of cellular organisms that includes the kingdom Monera (bacteria and blue-green algae) and is characterized by the prokaryotic condition, minute size (0.2–10 μm for bacteria), and absence of the nuclear organization, mitotic capacities, and complex organelles that typify the superkingdom Eukaryotae. SYN: Procaryotae.

prokaryote (pro-kar′e-ot)
A member of the superkingdom Prokaryotae; an organismic unit consisting of a single and presumably primitive moneran cell, or a precellular organism, which lacks a nuclear membrane, paired organized chromosomes, a mitotic mechanism for cell division, microtubules, and mitochondria. SEE ALSO: Prokaryotae, Monera, eukaryote. SYN: procaryote.

prokaryotic (pro′kar-e-ot′ik)
Pertaining to or characteristic of a prokaryote. SYN: procaryotic.

prolabial (pro-la′be-al)
Denoting the isolated central soft-tissue segment of the upper lip in the embryonic state and in an unrepaired bilateral cleft palate.

prolabium (pro-la′be-um)
1. The exposed carmine margin of the lip. 2. The isolated central soft-tissue segment of the upper lip in the embryonic state and in an unrepaired bilateral cleft palate. [pro- + L. labium, lip]

prolactin (PRL) (pro-lak′tin)
A protein hormone of the anterior lobe of the hypophysis that stimulates the secretion of milk and possibly, during pregnancy, breast growth. SYN: galactopoietic hormone, lactation hormone, lactogenic hormone, lactotropin, mammotropic factor, mammotropic hormone. [pro- + L. lac, lact-, milk, + -in]

prolactinoma (pro-lak-ti-no′ma)
SYN: prolactin-producing adenoma.

prolamines (pro-lam′enz, pro′la-menz, -minz)
Proteins insoluble in water or neutral salt solutions, soluble in dilute acids or alkalies, and in 50–90% alcohol; e.g., gliadin, zein, hordein; all have relatively high proline contents.

prolapse (pro-laps′)
1. To sink down, said of an organ or other part. 2. A sinking of an organ or other part, especially its appearance at a natural or artificial orifice. SEE ALSO: procidentia, ptosis. [L. prolapsus, a falling] p. of the corpus luteum ectropion of the corpus luteum, due to eversion of the granulosa membrane through the opening in the ruptured follicle; this occurs normally in certain animals. mitral valve p. excessive retrograde movement of one or both mitral valve leaflets into the left atrium during left ventricular systole, often allowing mitral regurgitation; responsible for the click-murmur of Barlow syndrome, and rarely may be due to rheumatic carditis, a connective tissue disorder such as Marfan syndrome, or ruptured chorda tendinea (“flail mitral leaflet”). Morgagni p. chronic inflammation of Morgagni ventricle. p. of umbilical cord presentation of part of the umbilical cord ahead of the fetus; it may cause fetal death due to compression of the cord between the presenting part of the fetus and the maternal pelvis. p. of the uterus downward movement of the uterus due to laxity and atony of the muscular and fascial structures of the pelvic floor, usually resulting from injuries of childbirth or advanced age; p. occurs in three forms; first degree p., the cervix of the prolapsed uterus is well within the vaginal orifice; second degree p., the cervix is at or near the introitus; third degree p. (procidentia uteri), the cervix protrudes well beyond the vaginal orifice. SYN: descensus uteri, falling of the womb. valvular p. p. that may involve any valve or combination of valves, but usually the mitral valve. Pulmonic valve p. is extremely rare.

prolective (pro′lek-tiv)
Pertaining to data collected by planning in advance proportional mortality ratio. Number of deaths from a given cause in a specified period, per 100 or per 1000 total deaths. [pro- + L. lego, pp. lectum, to gather]

prolepsis (pro-lep′sis)
Recurrence of the paroxysm of a periodical disease at regularly shortening intervals. [G. p., anticipation]

proleptic (pro-lep′tik)
Relating to prolepsis. SYN: subintrant.

proleukocyte (pro-loo′ko-sit)
SYN: leukoblast.

prolidase (pro′li-das)
SYN: proline dipeptidase.

proliferate (pro-lif′e-rat)
To grow and increase in number by means of reproduction of similar forms. [L. proles, offspring, + fero, to bear]

proliferation (pro-lif-e-ra′shun)
Growth and reproduction of similar cells. diffuse mesangial p. SYN: mesangial proliferative glomerulonephritis. gingival p. SYN: gingival hyperplasia.

proliferative, proliferous (pro-lif′er-a-tiv, -er-us)
Increasing the numbers of similar forms.

prolific (pro-lif′ik)
Fruitful; bearing many children. [L. proles, offspring, + facio, to make]

proligerous (pro-lij′er-us)
Germinating; producing offspring. [L. proles, offspring, + gero, to bear]

prolinase (pro′li-nas)
SYN: prolyl dipeptidase.

proline (Pro) (pro′len)
Pyrrolidine-2-carboxylic acid;the l-isomer is found in proteins, especially the collagens. SYN: pyrrolidine-2-carboxylate. p. aminopeptidase SYN: p. iminopeptidase. p. dehydrogenase SYN: pyrroline-2-carboxylate reductase, pyrroline-5-carboxylate reductase. p. dipeptidase an enzyme cleaving aminoacyl-l-p. bonds in dipeptides containing a C-terminal p. residue; a deficiency of this enzyme results in hyperimidodipeptiduria. SYN: imidodipeptidase, peptidase D, prolidase. p. iminopeptidase a hydrolase cleaving l-prolyl residues from the N-terminal position in peptides. SYN: p. aminopeptidase. p. oxidase SYN: pyrroline-2-carboxylate reductase, pyrroline-5-carboxylate reductase. p. racemase an enzyme that reversibly converts d-p. to l-p.. d-p. reductase an oxidoreductase reversibly reacting d-p. with NADH to produce 5-aminovalerate and NAD+.

prolyl (Pro, prolyl) (pro′lil)
The acyl radical of proline. p. dipeptidase an enzyme cleaving l-p.-amino acid bonds in dipeptides containing N-terminal p. residues. SYN: iminodipeptidase, prolinase, prolylglycine dipeptidase. p. hydroxylase an enzyme that catalyzes the hydroxylation of certain p. residues in collagen precursors using molecular oxygen, ferrous ion, ascorbic acid, and α-ketoglutarate; a vitamin C deficiency directly affects the activity of this enzyme; one form of this enzyme (p. 4-hydroxylase) synthesizes 4-hydroxyprolyl residues while another produces 3-hydroxyprolyl residues.

prolylglycine dipeptidase (pro′lil-gli′sen)
SYN: prolyl dipeptidase.

promastigote (pro-mas′ti-got)
Term now generally used instead of “leptomonad” or “leptomonad stage,” to avoid confusion with the flagellate genus Leptomonas. It denotes the flagellate stage of a trypanosomatid protozoan in which the flagellum arises from a kinetoplast in front of the nucleus and emerges from the anterior end of the organism; usually an extracellular phase, as in the insect intermediate host (or in culture) of Leishmania parasites. [pro- + G. mastix, whip]

promegaloblast (pro-meg′a-lo-blast)
The earliest of four maturation stages of the megaloblast. See erythroblast. SYN: pernicious anemia type rubriblast.

prometaphase (pro-met′a-faz)
The stage of mitosis or meiosis in which the nuclear membrane disintegrates and the centrioles reach the poles of the cell, while the chromosomes continue to contract.

promethazine hydrochloride (pro-meth′a-zen)
An antihistaminic with antiemetic properties, often used to enhance the efficacy of narcotics.

promethazine theoclate (pro-meth′a-zen)
Promethiazine salt of 8-chlorotheophylline; an antihistaminic drug used for motion sickness.

promethestrol dipropionate (pro-meth′es-trol di-pro′pe-o-nat)
A synthetic estrogen derived from stilbene.

promethium (Pm) (pro-me′the-um)
A radioactive element of the rare earth series, atomic no. 61; first chemically identified in 1945; 145Pm has the longest known half-life (17.7 years). [Prometheus, a Titan of G. myth who stole fire to give to mortals]

prominence (prom′i-nens) [TA]
In anatomy, tissues or parts that project beyond a surface. SYN: prominentia [TA] . [L. prominentia] Ammon p. an external p. in the posterior pole of the eyeball during early embryogenesis. canine p. SYN: canine eminence. cardiac p. the conspicuous external bulge appearing on the ventral aspect of the human embryo as early as at the fourth week, indicative of the precocious development of the heart. p. of facial canal [TA] the p. on the medial wall of the tympanic cavity above the vestibular (oval) window produced by the presence of the facial canal. SYN: prominentia canalis facialis [TA] . forebrain p. SYN: frontonasal p.. frontonasal p. the unpaired embryonic p. formed by the tissues surrounding the forebrain vesicle. SYN: forebrain eminence, forebrain p., frontonasal process. hepatic p. the conspicuous external bulge appearing dorsocaudal to the cardiac p. on the body of the human embryo at about the fourth week, indicating the precocious development of the liver. hypothenar p. SYN: hypothenar eminence. laryngeal p. [TA] the projection on the anterior portion of the neck formed by the thyroid cartilage of the larynx; serves as an external indication of the level of the fifth cervical vertebra. SYN: prominentia laryngea [TA] , Adam's apple, protuberantia laryngea, thyroid eminence. lateral nasal p. an ectodermally covered mesenchymal swelling separating the embryonic olfactory pit from the developing eye; the ala of the nose develops from it. SYN: lateral nasal fold, lateral nasal process. p. of lateral semicircular canal [TA] the slight bulge in the medial wall of the epitympanic recess caused by the proximity of the lateral semicircular canal. SYN: prominentia canalis semicircularis lateralis [TA] . mallear p. [TA] a small p. at the upper end of the stria mallearis produced by the lateral process of the malleus. SYN: prominentia mallearis [TA] . medial nasal p. an ectodermally covered mesenchymal swelling lying medial to the olfactory placode or pit in the embryo; the nasal tip and philtrum of the lip develop from it. SYN: medial nasal fold, medial nasal process. spiral p. of cochlear duct [TA] a projecting portion of the spiral ligament of the cochlea, bounding the lower edge of the stria vascularis and containing within it a blood vessel, the vas prominens. SYN: prominentia spiralis ductus cochlearis [TA] . styloid p. [TA] a rounded eminence on the posterior (mastoid) wall of the tympanic cavity corresponding to the base of the styloid process. SYN: prominentia styloidea [TA] . thenar p. SYN: thenar eminence. tubal p. SYN: torus tubarius. p. of venous valvular sinus a slight eminence on the external wall of a vein correlating with the valvular sinus immediately proximal to the leaflets of the venous valve. SYN: agger valvae venae.

prominens (prom′i-nens)
Prominent; in anatomy, denoting a prominence. [L.]

prominentia, pl .prominentiae (prom-i-nen′she-a, -she-e) [TA]
SYN: prominence. [L. fr. promineo, to jut out, be prominent] p. canalis facialis [TA] SYN: prominence of facial canal. p. canalis semicircularis lateralis [TA] SYN: prominence of lateral semicircular canal. p. laryngea [TA] SYN: laryngeal prominence. p. mallearis [TA] SYN: mallear prominence. p. spiralis ductus cochlearis [TA] SYN: spiral prominence of cochlear duct. p. styloidea [TA] SYN: styloid prominence.

promitochondria (pro-mi-to-kon′dre-a)
Mitochondrial precursors with little internal structure ( E.G., no cristae) and no proteins of electron transport. SYN: premitochondria.

Acronym for proximal myotonic myopathy.

promonocyte (pro-mon′o-sit)
SYN: premonocyte.

promontorium, pl .promontoria (prom′on-to′re-um, -re-a) [TA]
SYN: promontory. [L. a mountain ridge, a headland, fr. promineo, to jut out] p. cavi tympani [TA] SYN: promontory of tympanic cavity. p. ossis sacri [TA] SYN: sacral promontory.

promontory (prom′on-to-re) [TA]
An eminence or projection; a projection of a part. SYN: promontorium [TA] . [L. promontorium] pelvic p. SYN: sacral p.. sacral p. [TA] the most prominent anterior projection of the base of the sacrum. SYN: promontorium ossis sacri [TA] , pelvic p., p. of the sacrum. p. of the sacrum SYN: sacral p.. tympanic p. SYN: p. of tympanic cavity. p. of tympanic cavity [TA] a rounded eminence on the labyrinthine wall of the middle ear, caused by the first coil of the cochlea. SYN: promontorium cavi tympani [TA] , tuber cochleae, tympanic p..

promoter (pro-mo′ter)
1. In chemistry, a substance that increases the activity of a catalyst. 2. In molecular biology, a DNA sequence at which RNA polymerase binds and initiates transcription.

promotion (pro-mo′shun)
Stimulation of tumor induction, following initiation, by a promoting agent that may of itself be noncarcinogenic. health p. according to the World Health Organization, the process of enabling people to increase control over and improve their health; it involves the population as a whole in the context of their everyday lives, rather than focusing on people at risk for specific diseases and is directed toward action on the determinants or causes of health.

promyelocyte (pro-mi′e-lo-sit)
1. The developmental stage of a granular leukocyte between the myeloblast and myelocyte, when a few specific granules appear in addition to azurophilic ones. 2. A large uninuclear cell occurring in the circulating blood of persons with myelocytic leukemia. SYN: premyelocyte, progranulocyte. [pro- + G. myelos, marrow, + kytos, cell]

pronasion (pro-na′ze-on)
The point of the angle between the septum of the nose and the surface of the upper lip, found at the point where a tangent applied to the nasal septum meets the upper lip. [pro- + L. nasus, nose]

pronate (pro′nat)
1. To perform pronation of the forearm or foot. 2. To assume, or to be placed in, a prone position. [L. pronatus, fr. prono, pp. -atus, to bend forward, fr. pronus, bent forward]

pronation (pro-na′shun) [TA]
The condition of being prone; the act of assuming or of being placed in a prone position; a specific rotational motion of the forearm that moves the palm into a downfacing position, a specific rotational motion of the foot in which the plantar surface is rotated outward. p. of foot eversion and abduction of the foot, raising the lateral edge. p. of forearm rotation of the forearm in such a way that the palm of the hand faces backward when the arm is in the anatomic position, or downward when the arm is extended at a right angle to the body.

pronator (pro-na′ter, tor) [TA]
A muscle that turns a part into the prone position. See muscle. [L.]

prone (pron)
Denoting: 1. The body when lying face downward. 2. Pronation of the forearm or of the foot. [L. pronus, bending down or forward]

pronephros, pl .pronephroi (pro-nef′ros, -roy)
1. The definitive excretory organ of primitive fishes. SYN: head kidney. 2. In the embryos of higher vertebrates, a vestigial structure consisting of a series of tortuous tubules emptying into the cloaca by way of the primary nephric duct; in the human embryo, the p. is a very rudimentary and temporary structure, followed by the mesonephros and still later by the metanephros. SYN: forekidney, primordial kidney. [pro- + G. nephros, kidney]

pronograde (pro′no-grad)
Walking or resting with the body horizontal, denoting the posture of quadrupeds; opposed to orthograde. [L. pronus, inclined forward, + gradior, to walk]

pronometer (pro-nom′e-ter)
SYN: goniometer (3) .

pronormoblast (pro-nor′mo-blast)
The earliest of four stages in development of the normoblast. SEE ALSO: erythroblast. SYN: proerythroblast, rubriblast.

pronucleus, pl .pronuclei (pro-noo′kle-us, -kle-i)
1. One of a pair of nuclei undergoing fusion in karyogamy. 2. In embryology, the nuclear material of the head of the spermatozoon (male p.) or of the ovum (female p.), after the ovum has been penetrated by the spermatozoon; each p. normally carries a haploid set of chromosomes, so that the merging of the pronuclei in fertilization reestablishes diploidy.

proofreading (pruf′red-ing)
The property of certain polymerases, e.g., DNA polymerase, to use their exonuclease activity to remove erroneously introduced bases and to replace them with the correct bases.

proopiomelanocortin (POMC) (pro-o′pe-o-mel′a-no-kor′tin)
A large molecule found in the anterior and intermediate lobes of the pituitary gland, the hypothalamus, and other parts of the brain as well as in the lungs, gastrointestinal tract, and placenta; the precursor of ACTH, CLIP, β-LPH, γ-MSH, β-endorphin, and met-enkephalin.

prootic (pro-o′tik)
In front of the ear. [pro- + G. ous, ear]

pro-oxidants (pro-oks′i-dants)
Compounds or agents capable of generating toxic oxygen species. Cf.:antioxidant.

propafenone (pro-paf′e-non)
Antiarrhythmic agent classified as a class IC type, thus resembling flecainide and encainide. Blocks fast sodium channels and has been used in the treatment of ventricular cardiac arrhythmias.

propagate (prop′a-gat)
1. To reproduce; to generate. 2. To move along a fiber, e.g., propagation of the nerve impulse. [L. propago, pp. -atus, to generate, reproduce]

propagation (prop-a-ga′shun)
The act of propagating.

propagative (prop-a-ga′tiv)
Relating to or concerned in propagation; denoting the sexual part of an animal or plant as distinguished from the soma.


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