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Medical Dictionary


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pyrophosphokinases (pi′ro-fos-fo-ki′nas-ez)
Enzymes (EC 2.7.6.x) transferring a pyrophosphoric group ( e.g., phospho-α-d-ribosyl-pyrophosphate synthetase). SYN: pyrophosphotransferases.

pyrophosphoric acid (pi′ro-fos-for′ik)
An anhydride of phosphoric acid obtained by heating phosphoric acid to 213°C; it forms pyrophosphates with bases, and its esters are important in energy metabolism and in biosynthesis.

pyrophosphorylases (pi′ro-fos-for′il-as-ez)
Trivial name applied to the nucleotidyltransferases that catalyze the transfer of the AMP of ATP to another residue with the release of inorganic pyrophosphate, or the attachment of a nucleoside pyrophosphate to a polynucleotide with release of inorganic orthophosphate.

pyrophosphotransferases (pi′ro-fos-fo-trans′fer-as-ez)
SYN: pyrophosphokinases.

pyropoikilocytosis (pi′ro-poy-kil-o-si-to-sis)
A rare recessive disorder manifested by severe hemolysis, marked poikilocytosis, and a characteristic sensitivity of the red cells to heat-induced fragmentation in vitro; apparently due to a defect in spectrin self-association. SYN: hereditary p.. hereditary p. SYN: p..

pyroscope (pi′ro-skop)
An instrument for measuring temperature by comparing the light of a heated object with a light standard. [pyro- + G. skopeo, to view]

pyrosis (pi-ro′sis)
Substernal pain or burning sensation, usually associated with regurgitation of acid-peptic gastric juice into the esophagus. SYN: heartburn. [G. a burning]

pyrotherapy (pi′ro-thar′a-pe)
Treatment of disease by inducing an artificial fever in the patient. SYN: therapeutic fever.

pyrotic (pi-rot′ik)
1. Relating to pyrosis. 2. SYN: caustic.

pyrotoxin (pi′ro-tok′sin)
Obsolete term for a toxic substance produced in the tissues during the progress of a fever.

pyroxylin (pi-rok′si-lin)
Consists chiefly of cellulose tetranitrate, obtained by the action of nitric and sulfuric acids on cotton; used in the preparation of collodion. SYN: colloxylin, dinitrocellulose, nitrocellulose, soluble gun cotton, xyloidin. [pyro- + G. xylon, wood]

pyrrobutamine phosphate (pir-o-bu′ta-men)
An antihistamine.

pyrrolase (pir′o-las)
SYN: tryptophan 2,3-dioxygenase.

pyrrol blue (pir′ol) [C.I. 42700]
An acid triarylmethane dye employed as a vital dye and as an elastin stain. SYN: Isamine blue.

pyrrole (pir′ol)
Divinylenimine;a heterocyclic compound found in many biologically important substances. SYN: azole, imidole.

pyrrolidine (pi-rol′i-den)
1. Tetrahydropyrrole;pyrrole to which four H atoms have been added; the structural basis of proline and hydroxyproline. 2. A class of alkaloids containing a p. (1) moiety or a p. derivative.

pyrrolidine-2-carboxylate
SYN: proline.

pyrrolidone-5-carboxylate (pi-rol′i-don)
SYN: 5-oxoproline.

5-pyrrolidone-2-carboxylic acid
SYN: 5-oxoproline.

pyrroline (pir′o-len)
A group of isomers of pyrrole to which two H atoms have been added; 1-p. has a double bond between the nitrogen and an adjacent carbon.

1-pyrroline-5-carboxylate dehydrogenase
An enzyme that catalyzes the reversible reaction of 1-pyrroline 5-carboxylate and NAD+ to form l-glutamate and NADH; this enzyme plays a role in proline and ornithine metabolism; 1-pyrroline 5-carboxylate is in equilibrium with glutamate γ-semialdehyde; a deficiency of this enzyme is associated with type II hyperprolinemia.

pyrroline-2-carboxylate reductase
An oxidoreductase reducing 1-pyrroline-2-carboxylate to l-proline with NAD(P)H. SYN: proline dehydrogenase, proline oxidase.

pyrroline-5-carboxylate reductase
An oxidoreductase reversibly reducing 1-pyrroline-5-carboxylate to l-proline with NAD(P)H; a deficiency of this enzyme is associated with type I hyperprolinemia. SYN: proline dehydrogenase, proline oxidase.

pyruvaldoxine (pi′roo-val-dok′sen)
SYN: isonitrosoacetone.

pyruvate (pi′roo-vat)
A salt or ester of pyruvic acid. active p. an intermediate formed in the oxidative decarboxylation of p.. Cf.:p. dehydrogenase (lipoamide). SYN: α-lactyl-thiamin pyrophosphate. p. carboxylase ligase catalyzing reaction of ATP, p., and HCO32−, to form ADP, orthophosphate, and oxaloacetate; biotin and acetyl-CoA are involved; an absence of this enzyme results in neuronal loss in the cerebral cortex, leading to mental retardation. p. decarboxylase α-carboxylase; α-ketoacid carboxylase;a thiamin-pyrophosphate–dependent carboxylase of yeast catalyzing decarboxylation of a 2-oxoacid ( e.g., p.) to an aldehyde ( e.g., acetaldehyde) without oxidoreduction and without lipoamide, in contrast to p. dehydrogenase (lipoamide). p. dehydrogenase a structurally distinct collection of enzymes containing p. dehydrogenase (lipoamide), dihydrolipoyl transacetylase, and dihydrolipoyl dehydrogenase. p. dehydrogenase (cytochrome) an oxidoreductase catalyzing reaction between ferricytochrome b1 and p. to yield acetate and CO2, and ferrocytochrome b1. p. dehydrogenase (lipoamide) an oxidoreductase catalyzing conversion of p. and (oxidized) lipoamide to CO2 and S6-acetyldihydrolipoamide in two successive reactions: the first between p. and thiamin pyrophosphate to yield CO2 and α-hydroxyethylthiamin pyrophosphate (active p.); the second between the last named and lipoamide to regain the thiamin pyrophosphate and yield S6-acetylhydrolipoamide. Cf.:α-ketodecarboxylase. p. kinase (PK) phosphoenolp. kinase;a phosphotransferase catalyzing transfer of phosphate from phosphoenolp. to ADP, forming ATP and p.; other nucleoside phosphates can participate in the reaction; a key step in glycolysis; a deficiency in p. kinase will lead to hemolytic anemia. p. oxidase an oxidoreductase catalyzing the reaction of p., phosphate, and O2 to yield acetyl phosphate, CO2, and H2O2.

pyruvic acid (pi-roo′vik)
2-Oxopropanoic acid; α-ketopropionic acid; acetylformic acid; pyroacemic acid;the simplest α-keto acid; an intermediate compound in the metabolism of carbohydrate; in thiamin deficiency, its oxidation is retarded and it accumulates in the tissues, especially in nervous structures. The enol form, enol p., when phosphorylated, plays an important metabolic role. See phosphoenolp..

pyruvic aldehyde
SYN: methylglyoxal.

pyruvic-malic carboxylase
SYN: malate dehydrogenase.

6-pyruvoyltetrahydropterin synthase (6-PTS)
An enzyme that catalyzes a step in the synthesis of tetrahydrobiopterin; a deficiency of this enzyme will result in one form of hyperphenylalaninemia.

pyrvinium pamoate (pir-vin′i-um)
A highly effective drug used in the eradication of human pinworms. SYN: viprynium embonate.

Pythium insidiosum (pith′e-um in-sid′e-um)
A species of fungi found in water or wet soil, and a cause of hyphomycosis or pythiosis.

pythogenesis (pi-tho-jen′e-sis)
1. Origination from decaying matter. 2. The causation of decay. [G. pytho, to decay, + genesis, origin]

pythogenic, pythogenous (pi-tho-jen′ik, pi-thoj′e-nus)
Originating from filth or putrescence.

pyuria (pi-u′re-a)
Presence of pus in the urine when voided. [G. pyon, pus, + ouron, urine]

p-rosolic acid (ro-sol′ik)
SYN: aurin.

p-sulfamylacetanilide (sul′fa-mil-as-e-tan′il-id)
SYN: N4-acetylsulfanilamide.

p-terphenyl (ter-fen′il)
C6H5–C6H4–C6H5;useful as a primary scintillator in liquid scintillation counting.




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