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Medical Dictionary - Dictionary of Medicine and Human Biology


Medical Dictionary


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deoxyribosyl (de-oks-e-ri′bo-sil)
The radical formed from deoxyribose by removal of the OH from the C-1 carbon; e.g., deoxyadenosine. Cf.:deoxyriboside.

deoxyribosyltransferases (de-oks′e-ri′bo-sil-trans′fer- as-es)
Enzymes that catalyze the transfer of 2-deoxy-d-ribose from deoxyribosides to free bases.

deoxyribotide (de-oks-e-ri′bo-tid)
Misnomer for deoxyribonucleotide or deoxynucleotide derived, by analogy with nucleoside-nucleotide, from incorrect usage of deoxyriboside.

deoxyribovirus (de-ok′se-vi′rus)
SYN: DNA virus.

deoxythymidine (dT) (de-oks′e-thi′mi-den)
SYN: thymidine.

deoxythymidylic acid (dTMP) (de-oks′e-thi-mi-dil′ik)
A component of DNA; originally and properly called thymidylic acid, but use of deoxy- is less ambiguous, as ribothymidylic acid is now known to exist. SYN: thymine deoxyribonucleotide.

deoxyuridine (de-oks′e-ur′i-den)
A derivative of uridine in which one or more of the hydroxyl groups on the ribose moiety has been replaced by a hydrogen; e.g., 2′-d. is a rare naturally occurring deoxynucleoside.

deozonize (de-o′zo-niz)
To deprive of ozone.

dependence (de-pen′dens)
The quality or condition of relying upon, being influenced by, or being subservient to a person or object reflecting a particular need. [L. dependeo, to hang from] anchorage d. the need of normal cells to have an appropriate surface to attach to in order for them to grow in culture. substance d. a pattern of behavioral, physiologic, and cognitive symptoms that develop due to substance use or abuse; usually indicated by tolerance to the effects of the substance and withdrawal symptoms that develop when use of the substance is terminated.

dependency (de-pen′dens-e)
The state of being dependent. pyridoxine d. with seizure an inherited disorder (autosomal recessive) apparently associated with deficient brain type I glutamate decarboxylase; seizures can be controlled with vitamin B6.

Dependovirus (de-pen′do-vi-rus)
A genus of small defective single-stranded DNA viruses in the family Parvoviridae that depend on adenoviruses for replication. SYN: adeno-associated virus, adenosatellite virus. [L. dependeo, to be dependent upon, + virus]

depersonalization (de-per′son-al-i-za′shun)
A state in which one loses the feeling of one's own identity in relation to others in one's family or peer group, or loses the feeling of one's own reality. SYN: d. syndrome.

de Pezzer
O., 19th century French physician. See de Pezzer catheter.

dephasing
In magnetic resonance imaging, following alignment by a radiofrequency pulse, the gradual loss of orientation of the magnetic atomic nuclei due to random molecular energy transfer or relaxation.

dephosphorylation (de-fos′for-i-la′shun)
Removal of a phosphoric group, usually hydrolytically and by enzyme action, from a compound.

depigmentation (de-pig-men-ta′shun)
Loss of pigment which may be partial or complete. SEE ALSO: achromia (1) .

depilate (dep′i-lat)
To remove hair by any means. Cf.:epilate. [L. de-pilo, pp. -atus, to deprive of hair, fr. de- neg. + pilo, to grow hair]

depilation (dep-i-la′shun)
SYN: epilation.

depilatory (de-pil′a-to-re)
1. SYN: epilatory (1) . 2. An agent that causes the falling out of hair. SYN: epilatory (2) . chemical d. a topically applied d. substance.

depletion (de-ple′shun)
1. The removal of accumulated fluids or solids. 2. A reduced state of strength from too many free discharges. 3. Excessive loss of a constituent, usually essential, of the body, e.g., salt, water, etc. salt d. excessive loss of sodium chloride from the body in urine, sweat, etc.; a cause of secondary dehydration. water d. reduction in the total volume of body water; dehydration.

depolarization (de-po′lar-i-za′shun)
1. A relative reduction in magnitude of polarization; in nerve cells, d. may result from an increase in the permeability of the cell membrane to sodium ions. 2. The destruction, neutralization, or change in direction of polarity. dendritic d. the loss of a negative charge in the dendrites of a nerve cell.

depolarize (de-po′lar-iz)
To deprive of polarity.

depolymerase (de-pol′i-mer-as)
Name used originally, before hydrolytic action was understood, for an enzyme catalyzing the hydrolysis of a macromolecule to simpler components. See nuclease.

deposit (de-poz′it)
1. A sediment or precipitate. 2. A pathological accumulation of inorganic material in a tissue. [L. de-pono, pp. -positus, to lay down] brickdust d. a sediment of urates in the urine. SYN: sedimentum lateritium.

depravation (dep′ra-va′shun)
SYN: depravity. [L. depravatio, fr. depravo, pp. -atus, to corrupt]

depraved (de-pravd′)
Deteriorated or degenerate; corrupt. [L. depravo, to corrupt]

depravity (de-prav′i-te)
A depraved act or the condition of being depraved. SYN: depravation.

deprenyl (de′pren-il)
An inhibitor of monoamine oxidase selective for the type B isozyme. The drug is used as an antiparkinsonian agent. It does not give rise to the hypertensive crisis that can occur when nonselective monoamine oxidase inhibitors are taken in the presence of dietary sources of tyramine. SYN: selegiline.

depressant (de-pres′ant)
1. Diminishing functional tone or activity. 2. An agent that reduces nervous or functional activity, such as a sedative or anesthetic. [L. de-primo, pp. -pressus, to press down]

depressed (de-prest′)
1. Flattened from above downward. 2. Below the normal level or the level of the surrounding parts. 3. Below the normal functional level. 4. Dejected; lowered in spirits.

depression (de-presh′un) [TA]
1. Reduction of the level of functioning. 2. SYN: excavation (1) . 3. Displacement of a part downward or inward. 4. A temporary mental state or chronic mental disorder characterized by feelings of sadness, loneliness, despair, low self-esteem, and self-reproach; accompanying signs include psychomotor retardation or less frequently agitation, withdrawal from social contact, and vegetative states such as loss of appetite and insomnia. SYN: dejection (1) , depressive reaction, depressive syndrome. [L. depressio, fr. deprimo, to press down] agitated d. d. with excitement and restlessness. anaclitic d. impairment of an infant's physical, social, and intellectual development following separation from its mother or from a mothering surrogate; characterized by listlessness, withdrawal, and anorexia. endogenous d. any depressive disorder occurring in the absence of external precipitants and believed to have a biologic origin. SYN: endogenomorphic d., nonreactive d.. exogenous d. similar signs and symptoms as endogenous d. but the precipitating factors are social or environmental and outside the individual. involutional d. d. or psychosis first occurring in the involutional years (40 to 55 for women, 50 to 65 for men). lingual salivary gland d. an indentation on the lingual surface of the mandible within which a portion of the submandibular gland lies; it appears radiographically as a sharply circumscribed ovoid radiolucency between the mandibular canal and the inferior border of the posterior mandible. SYN: Stafne bone cyst, static bone cyst. major d. a mental disorder characterized by sustained d. of mood, anhedonia, sleep and appetite disturbances, and feelings of worthlessness, guilt, and hopelessness. Diagnostic criteria (DSM-IV) for a major depressive episode include a depressed mood, a marked reduction of interest or pleasure in virtually all activities, or both, lasting for at least 2 weeks. In addition, 3 or more of the following must be present: gain or loss of weight, increased or decreased sleep, increased or decreased level of psychomotor activity, fatigue, feelings of guilt or worthlessness, diminished ability to concentrate, and recurring thoughts of death or suicide. See endogenous d., exogenous d., bipolar disorder. SYN: clinical d., major depressive disorder.Approximately 20 million persons a year suffer depressive illness in the U.S. About 10% of men and 25% of women experience major d. at some time in their lives, and 15–30% of these commit suicide. The negative impact of this disease on the economy of the U.S. is estimated at $16 billion annually. Risk factors for d. are drug or alcohol abuse, chronic physical illness, stressful life events, social isolation, a history of physical or sexual abuse, and a family history of depressive illness. D. can be masked by substance abuse. In elderly persons it may be mistaken for senile dementia, and vice versa; the two may coexist. The disorder is believed to represent an electrochemical malfunction of the limbic system involving disturbances in the metabolism of the neurotransmitters dopamine and serotonin. In persons with familial d., the number of glial cells in the subgenual prefrontal cortex is significantly smaller than in mentally healthy persons. Treatment with psychopharmaceutical agents, including tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase (MAO) inhibitors, and others, effectively controls most cases of clinical d.. Cognitive psychotherapy has demonstrated some success in reversing d.. Refined methods of electroconvulsive shock therapy (ECT) have been used with increasing frequency since the 1980s, generally for cases that do not respond to other treatment. Even in severe d. the response rate with ECT is 80% or higher. This mode of therapy has a faster onset of action, causes fewer side effects than drug therapy, and is particularly useful in elderly patients. nonreactive d. SYN: endogenous d.. d. of optic disk [TA] the normally occurring d. or pit in the center of the optic disk. SYN: excavatio disci [TA] , excavatio papillae, excavation of optic disk, physiologic cup, physiologic excavation. pacchionian depressions SYN: granular foveolae, under foveola. postdrive d. slowing of the heart, often with a rate-dependent blockade of AV and/or VA conduction following rapid atrial stimulation. pterygoid d. SYN: pterygoid fovea. reactive d. a psychological state occasioned directly by an intensely sad external situation (frequently loss of a loved person), relieved by the removal of the external situation ( e.g., reunion with a loved person). spreading d. a decrease of activity evoked by local stimulation of the cerebral cortex and spreading slowly over the whole cortex.

depressive (de-pres′iv)
1. Pushing down. 2. Pertaining to or causing depression.

depressor (de-pres′or)
1. A muscle that flattens or lowers a part. 2. Anything that depresses or retards functional activity. 3. An instrument or device used to push certain structures out of the way during an operation or examination. 4. An agent that decreases blood pressure. SYN: hypotensor, vasodepressor (2) . [L. de-primo, pp. -pressus, to press down] tongue d. an instrument with a broad flat extremity used for pressing down the tongue to facilitate examination of the oral cavity and pharynx.

deprivation (dep′ri-va′shun)
Absence, loss, or withholding of something needed. emotional d. lack of adequate and appropriate interpersonal or environmental experiences, or both, usually in the early developmental years. sensory d. diminution or absence of usual external stimuli or perceptual experiences, commonly resulting in psychological distress and aberrant functioning if continued too long.

depsipeptide (dep′se-pep′tid)
An oligo- or polypeptide containing one or more ester bonds as well as peptide bonds. SEE ALSO: peptolide. [G. deseo, to knead, blend, + peptide]

depth (depth)
Distance from the surface downward. anesthetic d. the degree of central nervous system depression produced by a general anesthetic agent; a function of potency of the anesthetic and the concentration in which it is administered. focal d., d. of focus the greatest distance through which an object point can be moved while maintaining a clear image. SYN: penetration (3) .

deptropine citrate (dep′tro-pen)
An antihistaminic agent with anticholinergic properties. SYN: dibenzheptropine citrate.

depulization (de-pu′li-za′shun)
Destruction of fleas which convey the plague bacillus from animals to humans. [L. de, from, + pulex (pulic-), flea]

depurant (dep′u-rant)
1. An agent or means used to effect purification. 2. An agent that promotes the excretion and removal of waste material. [L. de- intens. + puro, pp. -atus, to make pure]

depuration (dep-u-ra′shun)
Purification; removal of waste products or foul excretions.

depurative (dep′u-ra-tiv)
Tending to depurate; depurant.

dequalinium acetate (de-kwah-lin′e-um)
An antimicrobial agent. SYN: decamine.

dequalinium chloride
Dequalinium acetate, with chloride replacing acetate, used as an antimicrobial agent primarily in lozenges for the treatment of mouth and throat infections.

de Quervain
Friedrich Joseph, Swiss surgeon, 1868–1940. See de Quervain disease, de Quervain tenosynovitis, de Quervain thyroiditis.

deradelphus (dar-a-del′fus)
Conjoined twins with a single head and neck and separate bodies below the thoracic level. See conjoined twins, under twin. [G. dere, neck, + adelphos, brother]

derailment (de-ral′ment)
A symptom of a thought disorder in which one constantly gets “off the track” in one's thoughts and speech; similar to loosening of association.

deranencephaly, deranencephalia (dar-an′en-sef′a-le, -se-fa′le-a)
1. Congenital malformation in which the head is absent, although there is a rudimentary neck. 2. Defect of the brain and upper part of the spinal cord. [G. dere, neck, + an-, priv., + kephale, head]

derangement (de-ranj′ment)
1. A disturbance of the regular order or arrangement. 2. Rarely used term for a mental disturbance or disorder. [Fr.]

Dercum
Francis X., U.S. neurologist, 1856–1931. See D. disease.

derealization (de-re′a-li-za′shun)
An alteration in one's perception of the environment such that things that are ordinarily familiar seem strange, unreal, or two-dimensional.

dereism (de′re-izm)
Mental activity in fantasy in contrast to reality. [L. de, away, + res, thing]

dereistic (de-re-is′tik)
Living in imagination or fantasy with thoughts that are incongruent with logic or experience.

derencephalia (dar-en-se-fa′le-a)
SYN: derencephaly.

derencephalocele (dar-en-sef′a-lo-sel)
In derencephaly, protrusion of the rudimentary brain through a defect in the upper cervical spinal canal. [G. dere, neck, + enkephalos, brain, + kele, hernia]

derencephaly (dar-en-sef′a-le)
Cervical rachischisis and anencephaly, a malformation involving an open cranial vault with a rudimentary brain usually crowded back toward bifid cervical vertebrae. SYN: derencephalia. [G. dere, neck, + enkephalos, brain]

derepression (de-re-presh′un)
A homeostatic mechanism for regulating enzyme production in an inducible enzyme system: an inducer, usually a substrate of a specific enzyme pathway, by combining with an active repressor (produced by a regulator gene) deactivates it; the release of the previously repressed operator is followed by enzyme production.

derivation (dar-i-va′shun)
1. The source or process of an evolution. SYN: revulsion. 2. The drawing of blood or the body fluids to one part to relieve congestion in another. [L. derivatio, fr. derivo, pp. -atus, to draw off, fr. rivus, a stream]

derivative (de-riv′a-tiv)
1. Relating to or producing derivation. 2. Something produced by modification of something preexisting. 3. Specifically, a chemical compound that may be produced from another compound of similar structure in one or more steps, as in replacement of H by an alkyl, acyl, or amino group.

derm-, derma-
The skin; corresponds to L. cut-. See entries under cut. [G. derma]

dermabrader (derm′a-brad-er)
A motor-driven device used in dermabrasion.

dermabrasion (der-ma-bra′zhun)
Operative procedure to efface acne scars or pits performed with sandpaper, rotating wire brushes, or other abrasive materials.

Dermacentor (der-ma-sen′ter)
An ornate, characteristically marked genus of hard ticks (family Ixodidae) that possess eyes and 11 festoons; it consists of some 20 species whose members commonly attack dogs, humans, and other mammals. [derm- + G. kentor, a goader] D. albopictus the winter tick, a species found principally on horses, cattle, elk, moose, and deer in Canada and the northern and western United States; it is a one-host tick, but humans are sometimes attacked when skinning or dressing deer. D. andersoni the wood tick; the vector of Rocky Mountain spotted fever; also transmits tularemia and causes tick paralysis; there are characteristic black and white markings on the large scutum of the male. D. marginatus a tick species found across Europe and the vector of a human rickettsiosis caused by Rickettsia slovaca. D. occidentalis the Pacific Coast tick, a species found on all domestic herbivores, deer, dogs, humans, and other animals in California and Oregon. D. reticulatus a common species attacking sheep, oxen, goats, and deer, and sometimes troublesome to humans; it is found in Europe, Asia, and America. D. variabilis the American dog tick, a species that is a common pest of dogs along the eastern seaboard of the U.S., a vector of tularemia, and a principal vector of Rickettsia rickettsii which causes Rocky Mountain spotted fever in the central and eastern U.S.; may also cause tick paralysis.

Dermacoccus (der-ma-kok′us)
A genus of Gram-positive, aerobic cocci found on human skin.

dermad (der′mad)
In the direction of the outer integument. [derm- + L. ad, to]

dermal (der′mal)
Relating to the skin. SYN: dermatoid (2) .

Dermanyssus gallinae (der-ma-nis′us ga-le′-ne)
The red hen-mite, a parasite of chickens, pigeons, and other birds; it sometimes attacks humans and causes an itching eruption, especially in sensitized individuals. SYN: Acarus gallinae. [derm- + G. nysso, to prick; L. gallina, hen]

dermat-
The skin. SEE ALSO: derm-, dermato-, dermo-. [G. derma]

dermatalgia (der-ma-tal′je-a)
Localized pain, usually confined to the skin. SYN: dermatodynia. [dermat- + G. algos, pain]




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