Medical Dictionary

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dithranol (dith′ra-nol)
SYN: anthralin.

Dittrich
Franz, German pathologist, 1815–1859. See D. plugs, under plug, D. stenosis.

diuresis (di-u-re′sis)
Excretion of urine; commonly denotes production of unusually large volumes of urine. [G. dia, throughout, completely, + ouresis, urination] alcohol d. d. following the ingestion of alcoholic beverages; due, in part, to inhibition of the output of antidiuretic hormone by the neurohypophysis. osmotic d. d. due to a high concentration of osmotically active substances in the renal tubules ( e.g., urea, sodium sulfate), which limit the reabsorption of water. water d. d. following the drinking of water; due to reduced secretion of the antidiuretic hormone of the neurohypophysis in response to the lowered osmotic pressure of the blood.

diuretic (di-u-ret′ik)
1. Promoting the excretion of urine. 2. An agent that increases the amount of urine excreted. cardiac d. a d. that acts by increasing function of the heart, and thereby improves renal perfusion. direct d. a d. whose primary effect is on renal tubular function. indirect d. a d. that acts by increasing cardiac function or by increasing the state of hydration. loop d. a class of d. agents ( e.g., furosemide, ethacrynic acid) that act by inhibiting reabsorption of sodium and chloride, not only in the proximal and distal tubules but also in Henle loop. mercurial diuretics d. drugs containing organic mercury ( e.g., Mercuhydrin) that promote substantial salt and water loss through the kidney. Among the first potent d. agents used in congestive heart failure, but now obsolescent. osmotic diuretics drugs, such as mannitol, which by their osmotic effects retain water during urine formation and thus dilute electrolytes in the urine, making resorption less efficient; they promote the elimination of water and electrolytes in the urine. potassium sparing diuretics d. agents that, unlike most diuretics, retain potassium; examples are triamterene and amiloride. Often used together with diuretics that promote the loss of both sodium and potassium. Used in hypertension and in congestive heart failure.

diurnal (di-er′nal)
1. Pertaining to the daylight hours; opposite of nocturnal. 2. Repeating once each 24 hours, e.g., a d. variation or a d. rhythm. Cf.:circadian. [L. diurnus, of the day]

divalence, divalency (di-va′lens, di-va′len-se)
SYN: bivalence.

divalent (di-va′lent, div′a-)
SYN: bivalent (1) .

divalproex sodium (di-val′pro-eks)
Pentanoic acid, 2-propyl-, sodium salt (2:1); an anticonvulsant used in absence seizures and related seizure disorders. Derived from valproic acid.

divarication (di′var-i-ka′shun)
SYN: diastasis (1) . [L. divaricare, to spread asunder]

divergence (di-ver′jens)
1. A moving or spreading apart or in different directions. 2. The spreading of branches of the neuron to form synapses with several other neurons. [L. di-, apart, + vergo, to incline]

divergent (di-ver′jent)
Moving in different directions; radiating.

diverticula (di-ver-tik′u-la)
Plural of diverticulum.

diverticular (di-ver-tik′u-lar)
Relating to a diverticulum.

diverticulectomy (di′ver-tik-u-lek′to-me)
Excision of a diverticulum.

diverticulitis (di′ver-tik-u-li′tis)
Inflammation of a diverticulum, especially of the small pockets in the wall of the colon which fill with stagnant fecal material and become inflamed; rarely, they may cause obstruction, perforation, or bleeding.

diverticuloma (di′ver-tik-u-lo′ma)
Development of a granulomatous mass in the wall of the colon. [diverticulum + G. -oma, tumor]

diverticulopexy (di-ver-tik′u-lo-pek-se)
An operation to obliterate a diverticulum without resecting it, usually by securing the tip to a nearby structure so the diverticulum no longer fills. [diverticulum + G. pexis, fixation]

diverticulosis (di′ver-tik-u-lo′sis)
Presence of a number of diverticula of the intestine, common in middle age; the lesions are acquired pulsion diverticula.

diverticulum, pl .diverticula (di-ver-tik′u-lum, u-la) [tA]
A pouch or sac opening from a tubular or saccular organ, such as the gut or bladder. [L. deverticulum (or di-), a by-road, fr. de-verto, to turn aside] allantoenteric d. SYN: allantoic d.. allantoic d. an endoderm-lined outpouching of the hindgut representing the primordium of the allantois; in most amniotes, it grows into the extraembryonic celom; in humans, the distal part of the allantoic lumen is rudimentary, not extending beyond the body stalk. SYN: allantoenteric d.. diverticula ampullae ductus deferentis [TA] SYN: diverticula of ampulla of ductus deferens. caliceal d. a congenital or acquired distention of a kidney calix that renders it susceptible to calculus formation. SEE ALSO: Fraley syndrome. cervical d. a d. in the neck derived from retention of part of one of the pharyngeal pouches (endodermal) or branchial grooves (ectodermal) of the embryo. diverticula of colon diverticula, which are herniations of mucosa and submucosa through or between fibers of the major muscle layer (muscularis propria) of the colon. Usually multiple, it occurs in 50% of western populations above the age of 70, but is much less common in other populations. Can cause bleeding and episodes of severe inflammation. SYN: colonic diverticula. colonic diverticula SYN: diverticula of colon. diverticula of ampulla of ductus deferens [TA] the irregular sacculations of the ampullary part of the ductus deferens near its termination in the ejaculatory duct. SYN: diverticula ampullae ductus deferentis [TA] . duodenal d. a d. of the duodenum, often of large size, that is occasionally found projecting from the duodenum near the duodenal papilla. epiphrenic d. a d. which originates just above the cardioesophageal junction and usually protrudes to the right side of the lower mediastinum. false d. a d. of the intestine that passes through a defect in the muscular wall of the gut and thus does not include a layer of muscle in its wall. Heister d. bulb of jugular vein. hypopharyngeal d. SYN: pharyngoesophageal d.. Kommerell d. not a true d., but a bulblike swelling at the origin of the left subclavian artery due to a remnant of the left fourth aortic arch; associated vascular ring compression syndromes involve persistent right aortic arch; the left subclavian artery may pass behind the esophagus; the d. may be large enough to compress the trachea and esophagus even after the vascular ring has been divided and may need to be resected or affixed to the chest wall or vertebral fascia. laryngotracheal d. a d. from the floor of the caudal end of the pharynx which gives rise to the epithelium and glands of the larynx, trachea, bronchi, and lungs. Once this d. separates from the foregut, it is referred to as a tube. Meckel d. the remains of the yolk stalk of the embryo, which, when persisting abnormally as a blind sac or pouch in the adult, is located on the ileum a short distance above the cecum; it may be attached to the umbilicus and, if the lining includes gastric mucosa, peptic ulceration and bleeding may result. metanephric d. an outgrowth from the caudal portion of the mesonephric duct on either side, which grows cephalodorsally to make contact with the masses of metanephrogenous tissue (nephric blastemas) and give rise to the epithelial lining of the ureter and of the pelvis and the collecting ducts of the kidney. Nuck d. SYN: processus vaginalis of peritoneum. pancreatic diverticula the ventral and dorsal endodermal buds from the embryonic foregut that constitute the primordia of the parenchyma of the pancreas. Pertik d. an abnormally deep recessus pharyngeus. pharyngoesophageal d. most common d. of the esophagus; a pulsion d. developing between the inferior pharyngeal constrictor and the cricopharyngeus muscle. SYN: hypopharyngeal d., Zenker d.. pituitary d. a tubular outgrowth of ectoderm from the stomodeum of the embryo; it grows dorsad toward the infundibular process of the diencephalon, around which it forms a cuplike mass, giving rise to the pars distalis and pars juxtaneuralis of the hypophysis. SYN: craniopharyngeal canal, hypophyseal pouch, Rathke d., Rathke pocket, Rathke pouch. pulsion d. a d. formed by pressure from within, frequently causing herniation of mucosa through the muscularis. Rathke d. SYN: pituitary d.. thyroid d., thyroglossal d. the endodermal bud from the floor of the embryonic pharynx; the primordium of the parenchyma of the thyroid gland. tracheobronchial d. the endodermal lung primordium which will give rise to the epithelial lining of the respiratory tract. SYN: lung bud. traction d. a d. formed by the pulling force of contracting bands of adhesion, occurring mainly in the distal esophagus, from tuberculous hilar or mediastinal lymphadenitis. true d. a term denoting a d. that includes all the layers of the wall from which it protrudes. urethral d. a saclike outpouching of the urethral wall, either from a congenital defect or, more commonly, as a result of chronic penetrating inflammation. ventricular d. a congenital outpouching of the right or left ventricle. vesical d. a d. of the bladder wall; may be either true or false type. Zenker d. SYN: pharyngoesophageal d..

divicine (di′vis-en)
A base with alkaloidal properties present in Lathyrus sativus that is responsible, in part at least, for the latter's poisonous action. See lathyrism.

divisio
SYN: division. divisiones anteriores plexus brachialis [TA] SYN: anterior divisions of (trunks of) brachial plexus, under division. d. autonomica systematis nervosi peripherici [TA] SYN: autonomic division of nervous system. d. lateralis dextra hepatis [TA] SYN: right lateral division of liver. d. lateralis sinistra left lobe of liver. d. lateralis sinistra hepatis [TA] SYN: left lateral division of liver. d. medialis dextra hepatis [TA] SYN: right medial division of liver. d. medialis sinistra hepatis [TA] SYN: left medial division of liver. divisiones posteriores plexus brachialis [TA] SYN: posterior divisions of (trunks of) brachial plexus, under division.

division (di-vizh′un)
A separating into two or more parts. SEE ALSO: ramus. SYN: divisio. anterior primary d. SYN: anterior ramus of spinal nerve. anterior divisions of (trunks of) brachial plexus [TA] portion of the superior, middle, and inferior trunks of the brachial plexus that are destined to serve the anterior or flexor compartments of the upper limb. SYN: divisiones anteriores plexus brachialis [TA] . autonomic d. of nervous system [TA] that part of the nervous system which represents the motor innervation of smooth muscle, cardiac muscle, and gland cells. It consists of two physiologically and anatomically distinct, mutually antagonistic components: the sympathetic and parasympathetic parts. In both of these parts the pathway of innervation consists of a synaptic sequence of two motor neurons, one of which lies in the spinal cord or brainstem as the presynaptic (preganglionic) neuron, the thin but myelinated axon of which (presynaptic (preganglionic) or B fiber) emerges with an outgoing spinal or cranial nerve and synapses with one or more of the postsynaptic (postganglionic or, more strictly, ganglionic) neurons composing the autonomic ganglia; the unmyelinated postsynaptic fibers in turn innervate the smooth muscle, cardiac muscle, or gland cells. The presynaptic neurons of the sympathetic part lie in the intermediolateral cell column of the thoracic and upper two lumbar segments of the spinal gray matter; those of the parasympathetic part compose the visceral motor (visceral efferent) nuclei of the brainstem as well as the lateral column of the second to fourth sacral segments of the spinal cord. The ganglia of the sympathetic part are the paravertebral ganglia of the sympathetic trunk and the lumbar and sacral prevertebral or collateral ganglia; those of the parasympathetic part lie either near the organ to be innervated or as intramural ganglia within the organ itself except in the head, where there are four discrete parasympathetic ganglia (ciliary, otic, pterygopalatine, and submandibular). Impulse transmission from presynaptic to postsynaptic neuron is mediated by acetylcholine in both the sympathetic and parasympathetic parts; transmission from the postsynaptic fiber to the visceral effector tissues is classically said to be by acetylcholine in the parasympathetic part and by noradrenalin in the sympathetic part; recent evidence suggests the existence of further noncholinergic, nonadrenergic classes of postsynaptic fibers. SYN: divisio autonomica systematis nervosi peripherici [TA] , pars autonomica systematis nervosi peripherici [TA] , autonomic part of peripheral nervous system&star, autonomic nervous system, involuntary nervous system, systema nervosum autonomicum, vegetative nervous system, visceral motor system, visceral nervous system. cleavage d. the rapid mitotic d. of the zygote with decrease in size of individual cells or blastomeres and the formation of a morula. SEE ALSO: cleavage (1) . conjugate d. simultaneous d. of haploid nuclei, as in Basidiomycota. craniosacral d. of autonomic nervous system SYN: parasympathetic part of autonomic d. of peripheral nervous system. direct nuclear d. SYN: amitosis. equatorial d. nuclear d. in which each chromosome divides equally. indirect nuclear d. SYN: mitosis. lateral d. of left liver left lobe of liver. left lateral d. of liver [TA] in the surgical schema for subdividing the liver, the portion that lies to the left of the approximately vertical plane of the left hepatic vein and includes the left posterior and anterior lateral segments (hepatic segments II and III); it corresponds with the left anatomic lobe of the liver, and so is demarcated externally by the falciform ligament on the diaphragmatic surface and by the fissures for the ligamentum venosum and ligamentum teres on the viscera surface. SYN: divisio lateralis sinistra hepatis [TA] . left medial d. of liver [TA] in the surgical schema for subdividing the liver, the portion that lies between the approximately vertical planes of the left and middle hepatic veins and includes the left medial segment (hepatic segment IV); on the diaphragmatic surface, it is approximately the left third of the anatomic right lobe of the liver; on the visceral surface, its inferior portion corresponds to the quadrate lobe. SYN: divisio medialis sinistra hepatis [TA] . meiotic d. SYN: meiosis. mitotic d. SYN: mitosis. multiplicative d. reproduction by simultaneous d. of a mother cell into a number of daughter cells. If the process occurs without fertilization of the mother cell, or encystment, the daughter cells are called merozoites; if they develop within a cyst, and usually after fertilization, they are called sporozoites. posterior primary d. SYN: posterior ramus of spinal nerve. posterior divisions of (trunks of) brachial plexus [TA] portion of the superior, middle, and inferior trunks of the brachial plexus that are destined to serve the posterior or extensor compartments of the upper limb. SYN: divisiones posteriores plexus brachialis [TA] . reduction d. reduction of chromosomes. Remak nuclear d. SYN: amitosis. right lateral d. of liver [TA] in the surgical schema for subdividing the liver, the portion that lies to the right of the approximately vertical plane of the right hepatic vein and includes the right anterior and posterior lateral segments (hepatic segments VI and VII); it is approximately the right third of the right anatomic lobe of the liver. SYN: divisio lateralis dextra hepatis [TA] . right medial d. of liver [TA] in the surgical schema for subdividing the liver, the portion that lies between the approximately vertical planes of the right and middle hepatic veins and includes the right anterior and posterior medial segments (hepatic segments V and VIII); it is approximately the middle third of the anatomic right lobe of the liver. SYN: divisio medialis dextra hepatis [TA] .

div. in p. aeg.
Abbreviation for L. divide in partes aequales, divide into equal parts.

divulse (di-vuls′)
To tear away or apart. [L. divello, pp. di-vulsus, to pull apart]

divulsion (di-vul′shun)
1. Removal of a part by tearing. 2. Forcible dilation of the walls of a cavity or canal.

divulsor (di-vul′ser, -sor)
An instrument for forcible dilation of the urethra or other canal or cavity.

Dix
M.R., 20th century British otologist. See D.-Hallpike maneuver.

dixyrazine (di-zir′a-zen)
A phenothiazine compound used as an antipsychotic.

dizygotic, dizygous (di′zi-got′ik, di-zi′gus)
Relating to twins derived from two separate zygotes, i.e., bearing the same genetic relationship as full sibs but sharing a common intrauterine environment. [G. di-, two, + zygotos, yoked together]

dizziness (diz′i-nes)
Imprecise term commonly used to describe various symptoms such as faintness, giddiness, imbalance, lightheadedness, unsteadiness, or vertigo. SEE ALSO: vertigo. [A. S. dyzig, foolish]

djenkolic acid (jeng-kol′ik)
S,S′-Methylenebiscysteine;a sulfur-containing amino acid, resembling cystine but with a methylene bridge between the two sulfur atoms; very insoluble. [djenkol bean, bean in which first isolated]

dl-
Prefix (in small capital letters) denoting a substance consisting of equal quantities of the two enantiomorphs, d and l; replaces the older dl- as a more exact definition of structure.

dl-narcotine (nar′ko-ten)
SYN: gnoscopine.

DM
Abbreviation for adamsite; diabetes mellitus; diastolic murmur; dopamine.

DMA
Abbreviation for dimethoxyamphetamine.

DMARD
Acronym for disease modifying antirheumatic drugs, under drug.

DMC
Abbreviation for p,p,′-dichlorodiphenyl methyl carbinol.

D.M.D.
Abbreviation for Doctor of Dental Medicine.

dmf, DMF
Abbreviation for decayed, missing, and filled teeth. SEE ALSO: dmfs caries index.

dmfs, DMFS
Abbreviation for decayed, missing, and filled surfaces. SEE ALSO: d. caries index.

DMPP
Abbreviation for dimethylphenylpiperazinium.

DMSA
See 99mTc-dimercaptosuccinic acid.

DMSO
Abbreviation for dimethyl sulfoxide.

DMT
Abbreviation for N,N-dimethyltryptamine.

DN
Abbreviation for dibucaine number.

DNA
Abbreviation for deoxyribonucleic acid. For terms bearing this abbreviation, see subentries under deoxyribonucleic acid.

DNA diagnostics
SYN: genetic testing. See DNA markers, familial screening, prenatal screening.

dnaG
SYN: primase.

DNA markers
Segments of chromosomal DNA known to be linked with heritable traits or diseases. Although the markers themselves do not produce the conditions, they exist in concert with the genes responsible and are passed on with them. Certain markers, restriction fragment length polymorphisms, consist of segments of DNA that can be identified on autoradiographs (produced after digestion of the DNA by restriction enzymes and segregation of the resulting fragments through gel electrophoresis).

DNAse, DNAase, DNase
Abbreviations for deoxyribonuclease.

DNP, Dnp
1. Abbreviation for 2,4-dinitrophenol. 2. Abbreviation for deoxyribonucleoprotein.

DNR
Abbreviation for “do not resuscitate.”

Dns, DNS
Abbreviations for dansyl.

D.O.
Abbreviation for Doctor of Osteopathy.

DOA
Abbreviation for dead on arrival.

dobutamine (do-bu′ta-men)
A synthetic derivative of dopamine characterized by prominent inotropic but weak chronotropic and arrhythmogenic properties; a cardiotonic agent.

DOC
Abbreviation for deoxycorticosterone; deoxycholate.

d'Ocagne
Philbert M., French mathematician, 1862–1938. See d'Ocagne nomogram.

doctor (dok′ter)
1. A title conferred by a university on one who has followed a prescribed course of study, or given as a title of distinction; as d. of medicine, laws, philosophy, etc. 2. A physician, especially one upon whom has been conferred the degree of M.D. by a university or medical school. [L. a teacher, fr. doceo, pp. doctus, to teach]

doctrine (dok′trin)
A particular system of principles taught or advocated. [L. doceo, to teach] Arrhenius d. the theory of electrolytic dissociation (1887) that became the basis of our modern understanding of electrolytes: in an electrically conductive solution ( e.g., acid, base, or salt), free ions are present before electrolysis, and the proportion of molecules dissociated into ions can be calculated from measurements of electrical conductivity as well as of osmotic pressure. SYN: Arrhenius law. humoral d. the ancient Greek theory of the four body humors (blood, yellow and black bile, and phlegm) that determined health and disease. The humors were associated with the four elements (air, fire, earth, and water), which in turn were paired with one of the qualities (hot, cold, dry, and moist). A proper and evenly balanced mixture of the humors characterized health of body and mind; an imperfect balance resulted in disease. Temperament of body or mind also was supposed to be determined, e.g., sanguine (blood), choleric (yellow bile), melancholic (black bile), or phlegmatic (phlegm). SYN: fluidism, humoralism, humorism. Monro d. a d. that states that the cranial cavity is a closed rigid box and that therefore a change in the quantity of intracranial blood can occur only through the displacement of or replacement by cerebrospinal fluid. SYN: Monro-Kellie d.. Monro-Kellie d. SYN: Monro d..

docusate calcium (dok′u-sat)
A surface-active agent used in the treatment of constipation as a nonlaxative fecal softener. SYN: dioctyl calcium sulfosuccinate.

docusate sodium
A surface-active agent used as a dispersing agent in topically applied preparations. After oral administration it lowers the surface tension of the gastrointestinal tract and is used in the treatment of constipation as a wetting agent and stool softener. SYN: dioctyl sodium sulfosuccinate.

dodecane (do′de-kan)
n-C12H26;a straight, unbranched, saturated hydrocarbon containing 12 carbon atoms; the 12th member of the alkane series that begins with methane.

dodecanoyl-CoA synthetase (do-dek′an-o-il-ko-asin′the-tas)
SYN: long-chain fatty acid-CoA ligase.

dodecarbonium chloride (do-de-kar-bo′ne-um)
An antiseptic.

dodecyl (do′de-sil)
The radical of dodecane. d. gallate an antioxidant. d. sulfate sodium d. sulfate.

Döderlein
Albert, S.G., German obstetrician, 1860–1941. See D. bacillus.

Doerfler
Leo G., U.S. audiologist, *1919. See D.-Stewart test.

Dogiel
Jan von, Russian anatomist and physiologist, 1830–1905. See D. cells, under cell.

Dogiel
Alexander S., Russian histologist, 1852–1922. See D. corpuscle.

dogma
A theory or belief that is formally stated, defined, and thought to be true. central d. the proposition that while genetic information is transferred from parent to offspring via DNA duplication, within the cell, genetic information is transferred from DNA to mRNA (transcription) and then to protein (translation); proposed by Francis Crick.

dogmatic (dog-mat′ik)
See d. school. [G. dogmatikos, concerning opinions; d. iatroi, physicians who go by general principles; fr. dogma, an opinion]

dogmatist (dog′ma-tist)
A follower of the dogmatic school.

Döhle
Karl G.P., German histologist and pathologist, 1855–1928. See D. bodies, under body, D. inclusions, under inclusion.

Doisy
Edward A., U.S. biochemist and Nobel laureate, 1893–1986. See Allen-D. test, Allen-D. unit.

dol (dol)
A unit measure of pain. [L. dolor, pain]

dolicho-
Long. [G. dolichos]

dolichocephalic, dolichocephalous (dol-i-ko-se-fal′ik, -sef′a-lus)
Having a disproportionately long head; denoting a skull with a cephalic index below 75. SYN: dolichocranial. [dolicho- + G. kephale, head]

dolichocephaly, dolichocephalism (dol-i-ko-sef′a-le, sef′a-lizm)
The condition of being dolichocephalic.

dolichocolon (dol-i-ko-ko′lon)
A colon of abnormal length. [dolicho- + G. kolon, colon]

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