Medical Dictionary

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dwarfism (dworf′izm)
A condition or a group of conditions in which the standing height of the person is below the 3rd percentile. achondroplastic d. achondroplasia. acromelic d. SYN: acromesomelic d.. acromesomelic d. a form of short-limb d. characterized by pug-nose and shortening particularly striking in the distal segment of the limbs, i.e., the forearms and lower legs, fingers and toes; autosomal recessive inheritance. SYN: acromelic d., acromesomelia. aortic d. underdevelopment of physical stature associated with severe aortic stenosis. asexual d. d. in which adult sexual development is deficient. ateliotic d. SYN: panhypopituitarism. camptomelic d. d. with shortening of the lower limbs due to anterior bending of the femur and tibia. chondrodystrophic d. chondrodystrophy. deprivation d. short stature due to emotional deprivation. SYN: psychosocial d.. diastrophic d. [MIM*222600] SYN: diastrophic dysplasia. disproportionate d. d. characterized by more significant shortening of the limbs or the trunk; when the limbs are primarily involved, the shortening may predominate in the proximal segments (rhizomelia), middle segments (mesomelia), or distal segments (acromelia); usually results from hereditary intrinsic skeletal dysplasias. Fröhlich d. d. with Fröhlich syndrome. Hunter-Thompson d. [MIM*201250] a severe form of acromesomelic d., characterized by shortening of the distal segments of the limbs; lower extremities are more severely affected than the upper limbs; often associated with dislocations of elbows, knees, and hips. Autosomal recessive inheritance, caused by mutations in the cartilage-derived morphogenetic protein 1 (CDMP1) gene on chromosome 20q. hypothyroid d. SYN: infantile hypothyroidism. infantile d. SYN: infantilism (1) . Laron type d. d. associated with an absent or very low levels of somatomedin C (insulinlike growth factor I) or abnormalities in receptor activity. lethal d. d. leading to intrauterine or neonatal death. Lorain-Lévi d. SYN: pituitary d.. mesomelic d. d. with shortness of the forearms and lower legs. metatropic d. [MIM*250600] a skeletal dysplasia characterized by disproportionate d. in which the trunk is long relative to the limbs at birth but undergoes reversal of this proportion with subsequent development with severe and progressive kyphoscoliosis; there is metaphyseal flare of long bones, the pelvis is halberd-shaped, and the coccyx is long, resulting in a sacral appendage; autosomal recessive inheritance. micromelic d. d. with abnormally short or small limbs. panhypopituitary d. type I is an autosomal recessive disorder with deficient human growth hormone, ACTH, FSH, etc., having delayed sexual development, hypothyroidism, and adrenal insufficiency; type II is similar but is an X-linked disorder. phocomelic d. d. in which the diaphyses of the long bones are abnormally short or the intermediate parts of the limbs are absent. physiologic d. d. characterized by normal development that is at a strikingly lesser rate than that for members of the same family, race, or other races. SYN: primordial d., true d.. pituitary d. a rare form of d. caused by the absence of a functional anterior pituitary gland; may be present at birth or develop during early childhood. SYN: Lorain-Lévi d., Lorain-Lévi infantilism, Lorain-Lévi syndrome, pituitary infantilism. primordial d. SYN: physiologic d.. proportionate d. d. characterized by a symmetric shortening of the limbs and trunk; generally results from chemical, endocrine, nutritional, or nonosseous abnormalities. psychosocial d. SYN: deprivation d.. rhizomelic d. one of the syndromes of chondrodysplasia punctata (q.v.), autosomal recessive, with variable skin keratinization disorders and variable facial, cardiac, optic, and central nervous system abnormalities; epiphyseal stippling is also present. There are multiple enzymatic defects, including peroxisomal ones, and affected infants fail to thrive and usually die in infancy. Robinow d. SYN: Robinow syndrome. Seckel d. SYN: Seckel syndrome. senile d. d. characterized by craniofacial anomalies with progeroid appearance. sexual d. d. with normal sexual development. Silver-Russell d. SYN: Silver-Russell syndrome. snub-nose d. [MIM*127100] d. characterized by low birth weight, snub nose, and stocky build; autosomal dominant inheritance. There is a similar autosomal recessive phenotype [MIM*223600]. SYN: dominantly inherited Lévi disease. thanatophoric d. a lethal d. characterized by micromelia, bowed long bones, enlarged head, flattened vertebral bodies, and muscular hypotonia; lack of pulmonary ventilation causes respiratory difficulties with cyanosis leading to death within the first few hours or days after birth. true d. SYN: physiologic d..

Dwyer
Frederick, English orthopaedic surgeon, 1920–1975. See D. osteotomy.

Dy
Symbol for dysprosium.

dyad (di′ad)
1. A pair. SYN: diad (2) . 2. In chemistry, a bivalent element. 3. A pair of persons in an interactional situation, e.g., patient and therapist, husband and wife. 4. The double chromosome resulting from the splitting of a tetrad during meiosis. 5. Two units treated as one. 6. A pair of cells resulting from the first meitotic division. [G. dyas, the number two, duality]

dyclonine hydrochloride (di′klo-nen)
A topical local anesthetic.

dydrogesterone (di-dro-jes′ter-on)
A synthetic steroid, derived from retroprogesterone, with progestational effects.

dye (di)
A stain or coloring matter; a compound consisting of chromophore and auxochrome groups attached to one or more benzene rings, its color being due to the chromophore and its dyeing affinities to the auxochrome. Dyes are used for intravital coloration of living cells, staining tissues and microorganisms, as antiseptics and germicides, and some as stimulants of epithelial growth. For individual dyes, see the specific names. Commonly but improperly used for radiographic contrast medium. [A.S. deah, deag] acidic dyes dyes that ionize in solution to produce negatively charged ions or anions; they consist of sodium salts of phenols and carboxylic acid dyes; their solutions tend to be neutral or slightly alkaline; examples are eosin and aniline blue. acridine dyes derivatives of the compound acridine that is closely related to xanthene; important as fluorochromes in histology, cytochemistry, and chemotherapy; examples include acriflavine, acridine orange, and quinacrine mustard. azin dyes d. derivatives of phenazine that include important histologic stains, such as neutral red, azocarmine G., and safranin O. azo dyes dyes in which the azo group is the chromophore and joins benzene or naphthalene rings; they include a large number of biologic stains, such as Congo red and oil red O; also used clinically to promote epithelial growth in the treatment of ulcers, burns, and other wounds; many have anticoagulant action. azocarmine dyes dyes giving a dark purplish red color as histologic stains. basic dyes dyes which ionize in solution to give positively charged ions or cations; the auxochrome group is an amine which can form a salt with an acid like HCl; solutions are usually slightly acidic; examples include basic fuchsin and toluidine blue O. chlorotriazine dyes dyes containing one or more chlorotriazine moieties that react with polysaccharides. diphenylmethane dyes dyes in which the central carbon connecting two phenyl groups lacks an amino or imino group; the chromophore is the quinoid ring; an alternative formulation is as a ketonimide; the most common example is auramine O. ketonimine dyes dyes in which the chromophore is &bivbond;C&dbond;NH connected to two benzene rings; alkylamino groups are added para to the methane carbon on both rings. The most important member for biological purposes is auramine O; an alternative formulation is as a diphenylmethane d.. natural dyes dyes obtained from animals or plants; examples include carmine, obtained from cochineal in the dried female insect Dactylopius coccus of Central America, and hematoxylin, extracted from the bark of the logwood tree Haematoxylon campechianum in the Caribbean area. nitro dyes dyes in which the chromophore is &cbond;NO2, which is so acidic that all dyes in this group are of the acid type; important examples in cytoplasmic staining are picric acid and naphthol yellow S. oxazin dyes similar to azin dyes except that one of the connecting N atoms is replaced by O; most important representatives are brilliant cresyl blue, orcein, litmus, and cresyl violet. rosanilin dyes several triaminotriphenylmethane dyes or mixtures of them often sold under the name of basic fuchsin; rosanilin dyes differ from other triphenylmethane dyes in that the amino groups are unsubstituted, and they may have methyl groups introduced directly onto the benzene rings; the four possible such dyes are pararosanilin, rosanilin, new fuchsin, and magenta II. salt d. SYN: neutral stain. synthetic dyes organic d. compounds originally derived from coal-tar derivatives; presently produced by synthesis from benzene and its derivatives; examples include eosin, methylene blue, and fluorescein. thiazin dyes similar to azin dyes except that one of the connecting N atoms is replaced by S; includes many important biologic stains, especially in hematology, e.g., azure A, azure B, and methylene blue. triphenylmethane dyes a group of dyes that includes pararosanilin, as well as many others used in histology and cytology; employed as nuclear, cytoplasmic, and connective tissue stains; important in histochemistry as in the preparation of Schiff reagent. xanthene dyes derivatives of the compound xanthene; include the pyronins, rhodamines, and fluoresceins.

Dyggve
Holger, Danish pediatrician, 1913–1984. See D.-Melchior-Clausen syndrome.

-dymus
1. Suffix to be combined with number roots; e.g., didymus, tridymus, tetradymus. 2. Occasionally used shortened form for -didymus. [G. -dymos, fold]

dynamics (di-nam′iks)
1. The science of motion in response to forces. 2. In psychiatry, used as a contraction of psychodynamics. 3. In the behavioral sciences, any of the numerous intrapersonal and interpersonal influences or phenomena associated with personality development and interpersonal processes. [G. dynamis, force] group d. a term used to represent the study of underlying features of group behavior, e.g., motives, attitudes; it is concerned with group change rather than with static characteristics.

dynamo-
Combining form denoting force, energy. [G. dynamis, power]

dynamogenesis (di′na-mo-jen′e-sis)
The production of force, especially of muscular or nervous energy. SYN: dynamogeny. [dynamo- + G. genesis, production]

dynamogenic (di′na-mo-jen′ik)
Producing power or force, especially nervous or muscular power or activity.

dynamogeny (di-na-moj′e-ne)
SYN: dynamogenesis.

dynamograph (di-nam′o-graf)
An instrument for recording the degree of muscular power. [dynamo- + G. grapho, to write]

dynamometer (di-na-mom′e-ter)
An instrument for measuring the degree of muscular power. SYN: ergometer. [dynamo- + G. metron, measure]

dynamoscope (di-nam′o-skop)
A modified stethoscope for auscultation of the muscles. [dynamo- + G. skopeo, to examine]

dynamoscopy (di-na-mos′ko-pe)
Auscultation of a contracting muscle.

dynatherm (di′na-therm)
An apparatus for inducing diathermy. [G. dynamis, force, + therme, heat]

dyne (din)
The unit of force in the CGS system, replaced in the SI system by the newton (1 N = 105 dynes), that gives a body of 1 g mass an acceleration of 1 cm/sec2; expressed as F (dynes) = m (grams) × a (cm/sec2). [G. dynamis, force]

dynein (din′en)
A protein associated with motile structures, exhibiting adenosine triphosphatase activity; it forms “arms” on the outer tubules of cilia and flagella. It functions as a molecular motor. SEE ALSO: tubulin, d. arm. [dyne + protein]

dynorphin (di′nor-fin)
An endogenous opioid ligand that acts as an agonist at opiate receptors. Extremely potent, widely distributed neuropeptide that has 17 amino acid residues and contains leu5-enkephalin as its NH2-terminal sequence.

dyphylline (di-fil′in)
Exhibits characteristic peripheral vasodilator and bronchodilator actions of other theophylline compounds.

dys-
Bad, difficult, un-, mis-; opposite of eu-. Cf.:dis-. [G.]

dysacousia, dysacusia (dis-a-ku′se-a)
SYN: dysacusis.

dysacusis (dis-a-ku′sis)
1. Any impairment of hearing involving difficulty in processing details of sound as opposed to any loss of sensitivity to sound. 2. Pain or discomfort in the ear from exposure to sound. SYN: dysacousia, dysacusia. [dys- + G. akousis, hearing]

dysadaptation (dis′ad-ap-ta′shun)
Inability of the retina and iris to accommodate well to varying intensities of light.

dysantigraphia (dis′an-te-graf′e-a)
A form of agraphia in which the subject is unable to copy written or printed matter. [dys- + G. antigrapho, to write back]

dysaphia (dis-a′fe-a, dis-af′e-a)
Impairment of the sense of touch. [dys- + G. haphe, touch]

dysaphic (dis-a′fik)
Relating to impaired tactile sensibility.

dysarteriotony (dis-ar-ter-e-ot′o-ne)
Abnormal blood pressure, either too high or too low. [dys- + G. arteria, artery, + tonos, tension]

dysarthria (dis-ar′thre-a)
A disturbance of speech due to emotional stress, to brain injury, or to paralysis, incoordination, or spasticity of the muscles used for speaking. SYN: dysarthrosis (1) . [dys- + G. arthroo, to articulate] ataxic d. d. caused by cerebellar lesions. hyperkinetic d. d. caused by chorea and myoclonus. hypokinetic d. d. caused by the rigid types of extrapyramidal disease. lower motor neuron d. d. caused by dysfunction of the motor nuclei and the lower pons or medulla, or other neural connections, central and peripheral to the muscles of articulation. rigid d. SYN: spastic d.. spastic d. d. caused by lesions along the corticobulbar tracts. SYN: rigid d..

dysarthric (dis-ar′thrik)
Relating to dysarthria.

dysarthrosis (dis-ar-thro′sis)
1. SYN: dysarthria. 2. Malformation of a joint. 3. A false joint. [dys- + G. arthrosis, joint]

dysautonomia (dis′aw-to-no′me-a)
Abnormal functioning of the autonomic nervous system. [dys- + G. autonomia, self-government] familial d. [MIM*223900] a congenital syndrome with specific disturbances of the nervous system and aberrations in autonomic nervous system function such as indifference to pain, diminished lacrimation, poor vasomotor homeostasis, motor incoordination, labile cardiovascular reactions, hyporeflexia, frequent attacks of bronchial pneumonia, hypersalivation with aspiration and difficulty in swallowing, hyperemesis, emotional instability, and an intolerance for anesthetics; autosomal recessive inheritance. Mapped to human chromosome 9q31–q33. SYN: Riley-Day syndrome.

dysbarism (dis′bar-izm)
General term for the symptom complex resulting from exposure to decreased or changing barometric pressure, including all physiologic effects resulting from such changes with the exception of hypoxia, and including the effects of rapid decompression. [dys- + G. baros, weight]

dysbasia (dis-ba′ze-a)
1. Difficulty in walking. 2. The difficult or distorted walking that occurs in persons with certain mental disorders. [dys- + G. basis, a step] d. angiosclerotica, d. angiospastica obsolete terms meaning intermittent difficulty in walking due to peripheral vascular causes. d. lordotica progressiva an affection characterized by lordoscoliosis of the lower portion of the vertebral column, occurring when the patient stands or walks and usually disappearing when the patient lies down. SYN: torsion neurosis.

dysbetalipoproteinemia (dis-ba′ta-lip-o-pro′ten-e′me-a)
SYN: type III familial hyperlipoproteinemia.

dysbolism (dis′bo-lizm)
Abnormal, but not necessarily morbid, metabolism, as in alkaptonuria. [dys- + G. bole (metabole), + -ismos, metabolism]

dysbulia (dis-boo′le-a)
Weakness and uncertainty of volition. [dys- + G. boule, will]

dysbulic (dis-boo′lik)
Relating to, or characterized by, dysbulia.

dyscalculia (dis-kal-ku′le-a)
Difficulty in performing simple mathematical problems; commonly seen in parietal lobe lesions. [dys- + L. calculo, to compute, fr. calculus, pebble, counter]

dyscephalia (dis-se-fa′le-a)
Malformation of the head and face. SYN: dyscephaly. [dys- + G. kephale, head] d. mandibulo-oculofacialis [MIM*234100] a syndrome of bony anomalies of the calvaria, face, and jaw, with brachygnathia, narrow curved nose, and multiple ocular defects including microphthalmia, microcornea, and cataract, often with alopecia overlying skull sutures, or alopecia areata, or absence of eyebrows. The pattern of inheritance is undecided. SYN: Hallermann-Streiff syndrome, Hallermann-Streiff-François syndrome, mandibulo-oculofacial syndrome, oculomandibulodyscephaly, oculomandibulofacial syndrome, progeria with cataract, progeria with microphthalmia.

dyscephaly (dis-sef′a-le)
SYN: dyscephalia.

dyscheiral, dyschiral (dis-ki′ral)
Relating to dyscheiria.

dyscheiria, dyschiria (dis-ki′re-a)
A disorder of sensibility in which, although there is no apparent loss of sensation, the patient is unable to tell which side of the body has been touched (acheiria), or refers it to the wrong side (allocheiria), or to both sides (syncheiria). [dys- + G. cheir, hand]

dyschezia (dis-ke′ze-a)
Difficulty in defecation. [dys- + G. chezo, to defecate]

dyschondrogenesis (dis-kon-dro-jen′e-sis)
Abnormal development of cartilage. [dys- + G. chondros, cartilage, + genesis, production]

dyschondroplasia (dis-kon-dro-pla′ze-a)
SYN: enchondromatosis. [dys- + G. chondros, cartilage, + plasis, a forming] d. with hemangiomas SYN: Maffucci syndrome.

dyschondrosteosis (dis′kon-dros-te-o′sis) [MIM*127300]
A skeletal dysplasia, more severe in females and with a female preponderance, characterized by bowing of radius, dorsal dislocation of the distal ulna with limited movement of the elbow and wrist (wrist deformity is called Madelung deformity), and mesomelic dwarfism; dominant inheritance, caused by mutation in the short stature homeobox gene (SHOX) on the pseudoautosomal region of Xp. Langer mesomelic dysplasia, the homozygous form of d., is also caused by homozygous mutations in the SHOX gene. SYN: Leri pleonosteosis, Leri-Weill disease, Leri-Weill syndrome. [dys- + G. chondros, cartilage, + osteon, bone, + -osis, condition]

dyschroia, dyschroa (dis-kroy′a, -kro′a)
A bad complexion; discoloration of the skin. [dys- + G. chroia, chroa, color]

dyschromatopsia (dis′kro-ma-top′se-a)
A condition in which the ability to perceive colors is not fully normal. Cf.:anomalous trichromatism, dichromatism, monochromatism, chromatopsia. [dys- + G. chroma, color, + opsis, vision]

dyschromatosis (dis-kro-ma-to′sis)
An asymptomatic anomaly of pigmentation occurring among the Japanese; may be localized or diffuse. [dys- + G. chroma, color, + -osis, condition]

dyschromia (dis-kro′me-a)
Any abnormality in the color of the skin.

dyscinesia (dis′si-ne′ze-a)
SYN: dyskinesia.

dyscontrol (dis-kon-trol′)
SYN: intermittent explosive disorder.

dyscoria (dis-ko′re-a)
Abnormality in the shape of the pupil. [dys- + G. kore, pupil of eye]

dyscrasia (dis-kra′ze-a)
1. A morbid general state resulting from the presence of abnormal material in the blood, usually applied to diseases affecting blood cells or platelets. 2. Old term indicating disease. [G. bad temperament, fr. dys- + krasis, a mixing] blood d. a diseased state of the blood; usually refers to abnormal cellular elements of a permanent character.

dyscrasic, dyscratic (dis-kra′sik, krat′ik)
Pertaining to or affected with dyscrasia.

dysdiadochokinesia, dysdiadochocinesia (dis-di-ad′o-ko-ki-ne′ze-a)
Impairment of the ability to perform rapidly alternating movements. [dys- + G. diadochos, working in turn, + kinesis, movement]

dysdiadochokinesis (dis′di-ad-o-ko-ki-ne′sis)
SYN: adiadochokinesis.

dysemia (dis-e′me-a)
Any abnormal condition or disease of the blood. [dys- + G. haima, blood]

dysencephalia splanchnocystica (dis′en-se-fa′le-a splangk-no-sis′ti-ka) [MIM*249000]
A malformation syndrome, lethal in the perinatal period, and characterized by intrauterine growth retardation, sloping forehead, occipital encephalocele, ocular anomalies, cleft palate, polydactyly, polycystic kidneys, and other malformations; autosomal recessive inheritance. Mapped to human chromosome 17q21–q24. SYN: Meckel syndrome, Meckel-Gruber syndrome.

dysenteric (dis-en-tar′ik)
Relating to or suffering from dysentery.

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