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Medical Dictionary


hydrochlorothiazide (hi′dro-klor-o-thi′a-zid)
A potent orally effective diuretic and antihypertensive agent related to chlorothiazide; can cause hypokalemia and hyperglycemia.

hydrocholecystis (hi′dro-ko-le-sis′tis)
Rarely used term for an effusion of serous fluid into the gallbladder. [hydro- + G. chole, bile, + kystis, bladder]

hydrocholeresis (hi′dro-ko-ler-e′sis, -kol-er-)
Increased output of a watery bile of low specific gravity, viscosity, and solid content. [hydro- + G. chole, bile, + hairesis, a taking]

hydrocholeretic (hi′dro-ko-ler-et′ik)
Pertaining to hydrocholeresis.

hydrocodone (hi-dro-ko′don)
A potent analgesic derivative of codeine used as an antitussive and analgesic. Often used combined with aspirin or acetaminophen. SYN: dihydrocodeinone.

hydrocolloid (hi-dro-kol′oyd)
A gelatinous colloid in unstable equilibrium with its contained water, useful in dentistry for impressions because of its dimensional stability under controlled conditions. irreversible h. a h. whose physical state is changed by an irreversible chemical reaction when water is added to a powder and an insoluble substance is formed. reversible h. a h. composed of a base substance whose physical state may be changed from a solid or semisolid to a liquid by the application of heat and then changed to that of an elastic gel by cooling.

hydrocolpocele, hydrocolpos (hi-dro-kol′po-sel, -kol′pos)
Accumulation of mucus or other nonsanguineous fluid in the vagina. [hydro- + G. kolpos, bosom (vagina)]

hydrocortamate hydrochloride (hi-dro-kor′ta-mat)
An ester-salt of hydrocortisone, used topically in the treatment of acute and chronic dermatoses.

hydrocortisone (hi-dro-kor′ti-son)
A reduction product (at C-11) of cortisone; a steroid hormone secreted by the adrenal cortex (the active hormone secreted in the greatest quantity by the adrenals) and the most potent of the naturally occurring glucocorticoids in humans; an antiinflammatory agent. SYN: cortisol. h. acetate an ester of h. with similar actions and uses as h.. SYN: cortisol acetate. h. cyclopentylpropionate an ester of h.. h. cypionate the cyclopentanepropionic ester of cortisone, for oral administration. h. hydrogen succinate a form of h. administered intravenously. h. sodium phosphate an anti-inflammatory agent for intravenous or intramuscular administration. h. sodium succinate a very soluble ester salt of h. (cortisol), used parenterally in the management of emergencies resulting from acute adrenal insufficiency.

hydrocotarnine (hi′dro-ko-tar′nen)
An alkaloidal principle derived from cotarnine; it is the basic hydrolytic product of narcotine; also obtained from the mother liquors of thebaine.

hydrocyanic acid (hi′dro-si-an′ik)
HCN;a colorless, very toxic liquid, with the odor of bitter almonds, present in bitter almonds (amygdalin), the stones of peaches, plums and other fruits, and laurel leaves; inhalation of 300 p.p.m. causes death. SYN: hydrogen cyanide, prussic acid.

hydrocyanism (hi-dro-si′an-izm)
Poisoning with hydrocyanic acid.

hydrocyst (hi′dro-sist)
A cyst with clear, watery contents. [hydro- + G. kystis, bladder]

hydrocystoma (hi′dro-sis-to′ma)
1. An eruption of deeply seated vesicles, due to retention of fluid in the sweat follicles. 2. SYN: hidrocystoma. [hydro- + G. kystis, bladder, + -oma, tumor]

hydrodipsia (hi-dro-dip′se-a)
Water thirst, a characteristic of animals that ordinarily drink water. [hydro- + G. dipsa, thirst]

hydrodipsomania (hi′dro-dip′so-ma′ne-a)
Periodic episodes of uncontrollable thirst, occasionally found in epileptic patients. [hydro- + G. dipsa, thirst, + mania, frenzy]

hydrodiuresis (hi′dro-di-u-re′sis)
Diuresis effected by water.

hydrodynamics (hi′dro-di-nam′iks)
The branch of physics concerned with the flow of liquids. [hydro- + G. dynamis, force]

hydroencephalocele (hi′dro-en-sef′a-lo-sel)
SYN: hydrencephalocele.

hydrofluoric acid (hi-dro-flor′ik)
A solution of hydrogen fluoride gas in water; a poisonous, caustic, foaming liquid that is used to clean metals and can etch glass; extremely irritating to skin and lungs.

hydrogel (hi′dro-jel)
A colloid in which the particles are in the external or dispersion phase and water in the internal or dispersed phase. Cf.:hydrosol.

hydrogen (H) (hi′dro-jen)
1. A gaseous element, atomic no. 1, atomic wt. 1.00794. 2. The molecular form (H2) of the element. SYN: dihydrogen. [hydro- + G. -gen, producing] activated h. h. removed by a dehydrogenase, e.g., via a flavoprotein, from a metabolite for transference to another substance with which it combines. arseniureted h. SYN: arsine. h. bromide HBr;a colorless gas that has a very irritating odor and fumes in moist air; in aqueous solution, it is hydrobromic acid. h. chloride HCl;a very soluble gas which, in solution, forms hydrochloric acid. h. cyanide SYN: hydrocyanic acid. h. dehydrogenase a flavoprotein catalyzing the conversion of NAD+ to NADH by molecular h. (H2); i.e., H2 + NAD+ → H+ + NADH. h. dioxide SYN: h. peroxide. heavy h. SYN: h.-2. h. peroxide an unstable compound readily broken down to water and oxygen, a reaction catalyzed by various powdered metals and by the enzyme, catalase; a 3% solution is used as a mild antiseptic for skin and mucous membranes. SYN: h. dioxide, hydroperoxide. h. phosphide SYN: phosphine. phosphureted h. SYN: phosphine. h. sulfide H2S;a colorless, flammable, toxic gas with a familiar “rotten egg” odor, formed in the decomposition of organic matter containing sulfur; used as a reagent, and in the manufacture of chemicals. SYN: sulfureted h.. sulfureted h. SYN: h. sulfide.

hydrogen-1 (1H)
The common h. isotope, making up 99.985% of the h. atoms occurring in nature. SYN: protium.

hydrogen-2 (2H)
The isotope of h. of atomic wt. 2; the less common stable isotope of h., making up 0.015% of the h. atoms occurring in nature; the nucleus consists of a proton and a neutron. SYN: deuterium, heavy hydrogen.

hydrogen-3 (3H)
A hydrogen isotope of atomic wt. 3; weakly radioactive, emitting beta particles to become the stable helium-3; half-life, 12.32 years. SYN: tritium.

hydrogenase (hi′dro-je-nas, hi-droj′e-nas)
1. Any enzyme that removes a hydride ion (or H:−) from NADH (or NADPH). SYN: hydrogenlyase. 2. The enzyme that catalyzes the reaction of 2H+ with ferricytochrome or ferredoxin to generate H2.

hydrogenation (hi′dro-je-na′shun, hi-droj′e-na-shun)
Addition of hydrogen to a compound, especially to an unsaturated fat or fatty acid; thus, soft fats or oils are solidified or “hardened.”

hydrogen exponent
The decadic logarithm of the hydrogen ion concentration in blood or other fluid; its negative is the pH of that fluid.

hydrogenlyase (hi′dro-gen-li′as)
SYN: hydrogenase (1) .

hydrokinetic (hi′dro-ki-net′ik)
Pertaining to the motion of fluids and the forces giving rise to such motion.

hydrokinetics (hi′dro-ki-net′iks)
That branch of kinetics concerned with fluids in motion.

hydrolabile (hi-dro-la′bil)
Unstable in the presence of water.

hydrolability (hi′dro-la-bil′i-te)
A state in which the fluid in the tissues readily changes in amount.

hydrolases (hi′dro-las-ez)
Enzymes (EC class 3) cleaving substrates with addition of H2O at the point of cleavage; e.g., esterases, phosphatases, nucleases, peptidases. SYN: hydrolyzing enzymes. cysteine h. h. that utilize an active site cysteinyl residue for the catalytic event. serine h. h. that utilize an active site seryl residue for the catalytic event.

hydro-lyases (hi-dro-li′as-ez)
A class of lyases (EC 4.2.1.x) comprising enzymes removing H and OH as water, leading to formation of new double bonds within the affected molecule; the trivial names usually contain dehydratase or hydratase.

hydrolymph (hi′dro-limf)
The circulating fluid in many of the invertebrates.

hydrolysate (hi-drol′i-sat)
A solution containing the products of hydrolysis.

hydrolysis (hi-drol′i-sis)
A chemical process whereby a compound is cleaved into two or more simpler compounds with the uptake of the H and OH parts of a water molecule on either side of the chemical bond cleaved; h. is effected by the action of acids, alkalies, or enzymes. Cf.:hydration. SYN: hydrolytic cleavage. [hydro- + G. lysis, dissolution]

hydrolytic (hi-dro-lit′ik)
Referring to or causing hydrolysis.

hydrolyze (hi′dro-liz)
To subject to hydrolysis.

hydroma (hi-dro′ma)
SYN: hygroma.

hydromassage (hi′dro-ma-sahzh)
Massage produced by streams of water.

hydromeningocele (hi′dro-men-ing′go-sel)
Protrusion of the meninges of brain or spinal cord through a defect in the bony wall, the sac so formed containing cerebrospinal fluid. [hydro- + G. meninx, membrane, + kele, hernia]

hydrometer (hi-drom′e-ter)
An instrument for determining the specific gravity or density of a liquid. SYN: areometer, gravimeter. [hydro- + G. meron, measure]

hydrometra (hi-dro-me′tra)
Accumulation of thin mucus or other watery fluid in the cavity of the uterus. [hydro- + G. metra, uterus]

hydrometric (hi-dro-met′rik)
Relating to hydrometry or the hydrometer.

hydrometrocolpos (hi′dro-me-tro-kol′pos)
Distention of uterus and vagina by fluid other than blood or pus. [hydro- + G. metra, uterus, + kolpos, bosom (vagina)]

hydrometry (hi-drom′e-tre)
Determination of the specific gravity of a fluid by means of a hydrometer.

hydromicrocephaly (hi′dro-mi-kro-sef′a-le)
Microcephaly associated with an increased amount of cerebrospinal fluid.

hydromorphone hydrochloride (hi-dro-mor′fon)
A synthetic derivative of morphine, with analgesic potency about 10 times that of morphine. SYN: dihydromorphinone hydrochloride.

hydromphalus (hi-drom′fa-lus)
A cystic tumor at the umbilicus, most commonly a vitellointestinal cyst. [hydro- + G. omphalos, umbilicus]

hydromyelia (hi-dro-mi-e′le-a)
An increase of fluid in the dilated central canal of the spinal cord, or in congenital cavities elsewhere in the cord substance. [hydro- + G. myelos, marrow]

hydromyelocele (hi-dro-mi′e-lo-sel)
Protrusion of a portion of cord, thinned out into a sac distended with cerebrospinal fluid, through a spina bifida. [hydro- + G. myelos, marrow, + kele, tumor, hernia]

hydronephrosis (hi′dro-ne-fro′sis)
Dilation of the pelvis and calices of one or both kidneys. This may result from obstruction to the flow of urine, vesicoureteral reflux, or it may be a primary congenital deformity without an apparent cause. SYN: pelvocaliectasis, pyeloureterectasis. [hydro- + G. nephros, kidney, + -osis, condition]

hydronephrotic (hi′dro-ne-frot′ik)
Relating to hydronephrosis.

hydronium (hi-dro′ne-um)
See h. ion.

hydroparasalpinx (hi′dro-par-a-sal′pinks)
Accumulation of serous fluid in the accessory tubes of the oviduct. [hydro- + G. para, beside, + salpinx, trumpet]

hydropathic (hi-dro-path′ik)
Relating to hydropathy.

hydropathy (hi-drop′a-the)
The obsolete use of water to treat and cure disease.

hydropenia (hi-dro-pe′ne-a)
Reduction or deprivation of water. [hydro- + G. penia, poverty]

hydropenic (hi-dro-pe′nik)
Pertaining to or characterized by hydropenia.

hydropericardium (hi′dro-par-i-kar′de-um)
A noninflammatory accumulation of fluid in the pericardial sac.

hydroperitoneum, hydroperitonia (hi′dro-par-i-to-ne′um, -to′ne-a)
SYN: ascites. [hydro- + peritoneum]

hydroperoxidases (hi′dro-per-oks′i-da-sez)
Those oxidoreductases that require H2O2 as hydrogen acceptors; e.g., peroxidases, catalase.

hydroperoxide (hi′dro-per-ok′sid)
SYN: hydrogen peroxide.

hydrophil, hydrophile (hi′dro-fil, -fil)
A substance that is hydrophilic.

hydrophilia (hi-dro-fil′e-a)
A tendency of the blood and tissues to absorb fluid. [hydro- + G. philos, fond]

hydrophilic (hi-dro-fil′ik)
1. Denoting the property of attracting or associating with water molecules, possessed by polar radicals or ions, as opposed to hydrophobic (2). 2. Tending to dissolve in water. 3. Polar. SYN: hydrophilous.

hydrophilous (hi-drof′i-lus)
SYN: hydrophilic.


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