Copy of `Dorland's Medical Dictionary`

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Dorland's Medical Dictionary Category: Health and Medicine > Medical Dictionary Date & country: 31/12/2010, USA Words: 39128

wuchereriasis
(voo-ker″e-ri´ә-sis) infection with roundworms of the genus Wuchereria; see also filariasis.

Wurster test
(for hydrogen peroxide) test paper is saturated with the solution of tetramethylparaphenylenediamine; hydrogen peroxide turns it to a blue-violet color. (for tyrosine) the suspected material is dissolved in boiling water and a little quinone; formation of a ruby-red color that changes slowly to brown is a po...

Wyburn-Mason syndrome
(wi´bәrn-ma´sәn) arteriovenous aneurysms on one or both sides of the brain, with ocular anomalies, especially in the retina, facial nevi, and sometimes mental retardation.

Wyeomyia virus
a virus belonging to the Bunyamwera serogroup of the genus Bunyavirus and occurring in Central and South America and Trinidad. It causes a febrile illness.

Xanax
(zan´aks) trademark for a preparation of alprazolam, an antianxiety agent.

xanthelasma
(zan″thәl-az´mә) planar xanthoma on an eyelid, characterized by soft light-colored spots or plaques.

xanthemia
(zan-the´me-ah) carotenemia.

xanthic
(zan´thik) yellow. pertaining to xanthine.

xanthine
(zan´thēn) a purine compound found in most bodily tissues and fluids; it is a precursor of uric acid. Methylated xanthine compounds such as caffeine, theobromine, and theophylline are used for their bronchodilator effects.

xanthine test
see specific tests, including Hoppe-Seyler test (def. 2) and Weidel test (defs. 2, 3).

xanthinuria
(zan″thin-u´re-ә) excess of xanthine in the urine, due to a hereditary disorder of purine metabolism in which there is a deficiency of the enzyme xanthine oxidase.

xanthochromatic
(zan″tho-kro-mat´ik) xanthochromic.

xanthochromia
(zan″tho-kro´me-ә) yellowish discoloration of the skin or spinal fluid. Xanthochromic spinal fluid usually indicates hemorrhage into the central nervous system and is due to the presence of xanthematin, a yellow pigment derived from hematin.

xanthochromic
(zan″tho-kro´mik) yellow-colored; called also xanthochromatic.

xanthocyanopsia
(zan″tho-si″ә-nop´se-ә) inability to perceive red or green tints, vision being limited to yellow and blue.

xanthoderma
(zan″tho-der´mә) any yellowish discoloration of the skin, as in carotenemia or jaundice.

xanthogranuloma
(zan″tho-gran″u-lo´mә) a tumor having histologic characteristics of both granuloma and xanthoma. juvenile xanthogranuloma a benign, self-limited disorder of infants and children, usually present at birth, characterized by a nodule or nodules of various colors, f...

xanthogranulomatous cholecystitis
a type of chronic cholecystitis characterized by proliferative fibrosis and infiltration by lipid-laden macrophages; it is often accompanied by obstruction from gallstones.

xanthoma
(zan-tho´mә) a benign tumor composed of lipid-laden foam cells (histiocytes containing lipid material). The most common types are in the skin, but xanthomas also appear elsewhere in the body, such as in bones, the heart, blood vessels, the liver, or other organs. adj., xantho´matous., adj.

xanthoma cell
foam cell (def. 2).

xanthomatosis
(zan″tho-mә-to´sis) any of various conditions marked by the presence of xanthomas. xanthomatosis bulbi fatty degeneration of the cornea due to disordered lipid metabolism and presence of xanthomas. chronic idiopathic xanthomatosis Hand-Schüller-...

xanthopsia
(zan-thop´se-ә) chromatopsia in which objects are seen as yellow.

xanthosine
(zan´tho-sēn) a nucleoside composed of xanthine and ribose.

xanthosis
(zan-tho´sis) yellowish discoloration; degeneration with yellowish pigmentation.

xanthurenic acid
(zanth″u-ren´ik) a metabolite of L-tryptophan, present in normal urine and in increased amounts in vitamin B6 deficiency.

Xe
xenon.

xenobiotic
(zen″o-bi-ot´ik) a chemical compound foreign to a given biological system. With respect to animals and humans, xenobiotics include drugs, drug metabolites, and environmental compounds such as pollutants that are not produced by the body. In the environment, xenobiotics include synthetic pesticides, herbicide...

xenodiagnosis
(zen″o-di″әg-no´sis) diagnosis by means of finding, in the feces of clean laboratory-bred bugs fed on the patient, infective forms of the organism causing a disease, such as in early stages of Chagas disease. diagnosis of trichinosis by taking meat suspected of being infected with Trichin...

xenogeneic
(zen″o-jә-ne´ik) in transplantation biology, denoting individuals or tissues from individuals of different species and hence of disparate cell type. Called also heterogenous and heterologous.

xenogeneic antigen
an antigen common to members of one species but not to members of other species; called also heterogeneic antigen.

xenogeneic transplantation
transplantation of a xenograft; called also heterotransplantation.

xenogenous
(zen-oj´ә-nәs) xenogeneic. caused by a foreign body.

xenograft
(zen´o-graft″) a graft of tissue transplanted between animals of different species; called also heterograft, heterologous graft, and heteroplastic graft.

xenon
(Xe) (ze´non) a chemical element, atomic number 54, atomic weight 131.30. The radioactive isotope 133Xe is used in assessment of pulmonary function, lung imaging, and cerebral blood flow studies. xenon-133 a radioisotope of xenon having a half-life of 5.3 days and a...

xenon arc lamp
one producing light of high intensity in a wide continuum of wavelengths; used with optical filters to simulate solar radiation.

xenoparasite
(zen″o-par´ә-sīt) an organism not usually parasitic on a particular species, but which becomes so because of a weakened condition of the host.

xenophobia
(zen″o-fo´be-ә) irrational fear of strangers.

xenophonia
(zen″o-fo´ne-ә) alteration in the quality of the voice.

xenophthalmia
(zen″of-thal´me-ә) inflammation caused by a foreign body in the eye.

Xenopsylla
(zen″op-sil´ә) a genus of fleas, including more than 30 species, many of which transmit disease-producing microorganisms. X. cheo′pis is the rat flea, which transmits Yersinia pestis, the causative organism of plague, as well as Rickettsia typhi, the causative organism of murine typhus.

xeroderma
(zēr″o-der´mә) excessive dryness of the skin, a mild form of ichthyosis. xeroderma pigmentosum a rare, autosomal recessive, sometimes fatal pigmentary and atrophic disease in which the skin and eyes are extremely sensitive to ultraviolet radiation. It begins in c...

xerography
(ze-rog´rә-fe) xeroradiography.

xeroma
(zēr-o´mә) xerophthalmia.

xeromammography
(zēr″o-mә-mog´rә-fe) xeroradiography of the breast.

xeromenia
(zēr″o-me´ne-ә) the appearance of constitutional symptoms at the menstrual period without any flow of blood.

xerophthalmia
(zēr″of-thal´me-ә) abnormal dryness and thickening of the surface of the conjunctiva and cornea due to a deficiency of vitamin A or to local disease; called also ophthalmoxerosis.

xeroradiography
(zēr″o-ra″de-og´rә-fe) the making of an x-ray image by a dry, totally photoelectric process, using metal plates coated with a semiconductor such as selenium; images produced differ from those of conventional radiography in that margins between tissues of varying densities are more clearly defined....

xerosialography
(zēr″o-si″ә-log´rә-fe) sialography in which the images are recorded by xerography.

xerosis
(zēr-o´sis) abnormal dryness, as of the eye (xerophthalmia), skin (xeroderma), or mouth (xerostomia).

xerostomia
(zēr″o-sto´me-ә) dryness of the mouth from salivary gland dysfunction; persons with this often have high rates of dental caries.

xerotomography
(zēr″o-tә-mog´rә-fe) tomography in which the images are recorded by xeroradiography.

xiphocostal
(zi″fo-) (zif″o-kos´tәl) pertaining to the xiphoid process and ribs.

xiphoid
(zif´oid) (zi´foid) sword-shaped; called also ensiform. xiphoid process.

xiphoid bone
xiphoid process.

xiphoid cartilage
xiphoid process.

xiphoid process
the pointed process of cartilage, supported by a core of bone, connected with the lower end of the sternum. Called also xiphoid.

xiphoiditis
(zi″foi-) (zif″oi-di´tis) inflammation of the xiphoid process.

xiphopagus
(zi-fop´-) (zĭ-fop´ә-gәs) symmetrical conjoined twins united in the region of the xiphoid process.

XO
symbol for the karyotype in which there is only one sex chromosome, an X chromosome, the other X or Y being absent; it is observed in most cases of Turner syndrome.

XXY syndrome
Klinefelter syndrome.

xylitol
(zi´lĭ-tol) a five-carbon sugar alcohol derived from xylose and as sweet as sucrose; used as a noncariogenic sweetener and also as a sugar substitute in diabetic diets.

Xylocaine
(zi´lo-kān) trademark for preparations of lidocaine, a topical anesthetic.

xylometazoline
(zi″lo-met″ә-zo´lēn) an adrenergic used in the form of the hydrochloride salt as a topical nasal decongestant.

xylose
(zi´lōs) a pentose found in mucopolysaccharides of connective tissue, sometimes the urine, and vegetable gum. D-Xylose is used in a diagnostic test of intestinal absorption (see malabsorption syndrome).

xylulose
(zi´lu-lōs) a pentose sugar occurring as D-xylulose and L-xylulose, one of the few L- sugars found in nature; it is sometimes excreted in the urine (see pentosuria).

xysma
(zis´mә) material resembling bits of membrane in stools of diarrhea.

Yale SK virus
a strain of poliovirus.

Yankauer sunction tip
(yang´kow-er) a tip attached to a suction tube for bedside suctioning of an artificial airway.

yaw
(yaw) a lesion of yaws. the deviation of an object from its usual path. mother yaw the initial cutaneous lesion of yaws; called also frambesioma.

yawning
(yawn´ing) a deep, involuntary inhalation with the mouth open, often accompanied by the act of stretching; called also oscitation.

yaws
(yawz) a highly infectious disease caused by the spirochete Treponema pertenue, transmitted primarily by direct contact with an infected person. The first symptom, usually about a month after exposure, is a single granulomatous lesion, an inflammatory but painless elevation of the skin. Called the “mother yaw,R...

Yb
ytterbium.

yeast
(yēst) any of various unicellular, nucleated, usually rounded fungi that reproduce by budding; some are fermenters of carbohydrates, and a few are pathogenic for humans. dried yeast dried cells of any suitable strain of Saccharomyces cerevisiae, usually a by-product of the brew...

yellow
(yel´o) a color between orange and green, produced by energy of wavelengths between 570 and 590 nm. a dye or stain with this color. visual yellow all-transretinal.

yellow adipose tissue
white adipose tissue.

yellow atrophy
massive hepatic necrosis.

yellow blindness
popular name for tritanopia.

yellow cartilage
elastic cartilage.

yellow fever
an acute, infectious type of hemorrhagic fever, transmitted by the female of certain species of mosquitoes, most commonly Aedes aegypti. Symptoms include sudden onset of intense fever, headache, muscular aches, and prostration. A few days after onset, the body temperature falls, only to rise again later. The pulse starts out rapid, b...

yellow fever vaccine
a preparation of attenuated yellow fever virus, used to immunize against yellow fever.

yellow fever virus
a flavivirus that causes yellow fever in Central and South America and Africa. It is transmitted by mosquitoes.

yellow ligaments
ligamenta flava.

yellow nail syndrome
a syndrome consisting of a yellow to greenish discoloration of the nails, which may be smooth, thickened, excessively curved on the long axis, and slow growing, and may become loose and be shed. It is often associated with lymphedema, especially of the lower limbs.

Yersinia
(yәr-sin´e-ә) a genus of nonmotile, oval or elongated, nonencapsulated, gram-negative bacteria (family Enterobacteriaceae). Y. pes´tis causes plague in humans and rodents; it is transmitted from rat to rat and from rat to human by the rat flea, and between humans by the human body louse. Y. enterocoli´tica c...

yin-yang principle
the Chinese philosophy that there are two energy flows within everything in the universe. Yang, the so-called “positive” principle, tends to stimulate and contract, and is linked to maleness, the sun, and heat. Yin, the so-called “negative” principle, tends to sedate and expand, and is linked to femaleness, da...

yoke
(yōk) a connecting structure. jugum.

yoked muscles
muscles that normally act simultaneously and equally, such as muscles involved in moving the eyes.

yolk
(yōk) the stored nutrient of the ovum.

yolk sac
the extraembryonic membrane connected with the midgut; in vertebrates below true mammals, it contains a yolk mass.

yolk sac carcinoma
yolk sac tumor a malignant germ cell tumor of children that represents a proliferation of both yolk sac endoderm and extraembryonic mesenchyme. It produces α-fetoprotein and most often occurs in the testes, but is also seen in the ovaries and some extragonadal sites. Called also endodermal sinus tumor.

Young operation
an operation for penile epispadias, with formation of a new urethral tube. perineal prostatectomy.

Young syndrome
(yung) obstructive azoospermia associated with chronic respiratory infections of sinuses and lungs.

Young test
(for cataract) on a disk with a varied number of pinholes in different portions, the patient's ability to recognize the number of holes is a test of the integrity of macular function.

Young-Helmholtz theory
the theory that color vision depends on three sets of retinal receptors, corresponding to the colors of red, green, and violet.

ytterbium
(Yb) (ĭ-tur´be-әm) a chemical element, atomic number 70, atomic weight 173.04.

yttrium
(Y) (ĭ´tre-әm) a chemical element, atomic number 39, atomic weight 88.905. yttrium 90 an artificial radioactive isotope of yttrium that emits high energy beta particles and localizes predominantly in bone; used as a tracer in nuclear medicine.

zafirlukast
(zә-fir´loo-kast) a leukotriene receptor antagonist used in treatment of asthma, administered orally.

Zahorsky disease
(zә-hor´ske) exanthema subitum.

zalcitabine
(zal-si´tә-bēn) a nucleoside analogueantiretroviral agent that inhibits the action of reverse transcriptase; used in the treatment of human immunodeficiency virus (HIV) infection, administered orally.

zaleplon
(zal´ә-plon) a nonbenzodiazepine sedative and hypnotic used in the short-term treatment of insomnia; administered orally.