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Medical Dictionary - Dictionary of Medicine and Human Biology


Medical Dictionary


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buttermilk
The fluid containing casein and lactic acid, left after the process of making butter.

butter yellow [C.I. 11160]
A fat-soluble yellow dye (MW 225) that has hepatic carcinogenic action in experimental animals; used as an indicator of pH (red, at pH 2.9, yellow at pH 4.0). SYN: dimethylaminoazobenzene, methyl yellow.

buttocks (but′oks) [TA]
The prominence formed by the gluteal muscles on either side. SYN: nates [TA] , clunes&star, breech.

button (but′on)
A structure, lesion, or device of knob shape. [M.E., fr. O.Fr. bouton, fr. bouter, to thrust, fr. Germanic] Biskra b. SYN: Oriental b.. Murphy b. a device used for intestinal anastomosis; it consists of two round, hollow cylinders that insert into each end of the transected intestine; the intestine is secured to each of the components with a suture and the ends are brought into approximation and the two cylinders joined with a locking mechanism; the apparatus is degradable and within approximately 10 days dissolves and is sloughed into the lumen of the intestine. A modification of an obsolete metal device bearing the same name. Oriental b. the lesion occurring in cutaneous leishmaniasis. SYN: Biskra b.. peritoneal b. a device used to drain ascitic fluid to subcutaneous space.

buttonhole (but′on-hol)
1. A short straight cut made through the wall of a cavity or canal. 2. The contraction of an orifice down to a narrow slit; i.e., the so-called mitral b. in extreme mitral stenosis. See b. stenosis.

butyl (bu′til)
CH3(CH2)3&cbond;;a radical of n-butane. b. alcohol several isomeric forms are known: primary b. alcohol, 1-butanol, propylcarbinol, the b. alcohol of fermentation; isobutyl alcohol, isopropylcarbinol, 2-methyl-1-propanol, which is narcotic in high concentrations; secondary b. alcohol, ethylmethylcarbinol, 2-butanol; and tertiary b. alcohol, trimethylcarbinol, 2-methyl-2-propanol, a denaturant for ethanol. b. aminobenzoate a local anesthetic, very insoluble and only slightly absorbed. SYN: butamben.

butylated hydroxyanisole (BHA) (boo-ti-lat′ed hi′drok-se-an′i-sol)
Exhibits antioxidant properties; often used with butylated hydroxytoluene propyl gallate, hydroquinone, methionine, lecithin, thiodipropionic acid, etc. Used as an antioxidant, especially in foods.

butylated hydroxytoluene (BHT)
Antioxidant for food, animal feed, petroleum products, synthetic rubbers, plastics, animal and vegetable oils, soap; also an antiskinning agent in paints and inks.

butylparaben (bu-til-par′a-ben)
An antifungal preservative.

butyraceous (bu-tir-a′shi-us)
Buttery in consistency.

butyrate (bu′ti-rat)
A salt or ester of butyric acid.

butyrate-CoA ligase
Fatty acid thiokinase (medium chain), a ligase forming acyl-CoA's from medium-chain fatty acids and CoA with the conversion of ATP to AMP and pyrophosphate. A key step in activation of fatty acids. SYN: acyl-activating enzyme (2) , butyryl-CoA synthetase, octanoyl-CoA synthetase.

butyric (bu-tir′ik)
Relating to butter.

butyric acid (bu-tir′ik)
An acid of unpleasant odor occurring in butter, cod liver oil, sweat, and many other substances. It exists in two forms: normal b. (also written as n-b.), butanoic acid, which occurs in combination with glycerol in cow's butter; and isobutyric acid, 2-methylpropanoic acid, one of the intermediates in valine catabolism, found in combination with glycerol in croton oil and elsewhere.

butyrocholinesterase (bu′tir-o-ko-lin-es′ter-as)
Pseudocholinesterase or plasma cholinesterase. To be distinguished from true or tissue cholinesterase. SEE ALSO: cholinesterase. SYN: butyrylcholine esterase, pseudocholinesterase.

butyroid (bu′ti-royd)
1. Buttery. 2. Resembling butter.

butyrometer (bu-ti-rom′e-ter)
An instrument for determining the amount of butterfat in milk. [G. boutyron, butter, + metron, measure]

butyrophenone (bu′tir-o-fe′non)
One of a group of derivatives of 4-phenylbutylamine that have neuroleptic activity; e.g., haloperidol.

butyrous (bu′ti-rus)
Denoting a tissue or bacterial growth of butterlike consistency.

butyryl (bu′ti-ril)
SYN: butanoyl.

butyrylcholine esterase (bu′ti-ril-ko′len es′ter-as)
SYN: butyrocholinesterase.

butyryl-CoA
Condensation product of coenzyme A and n-butanoic acid; an intermediate in fatty acid degradation and in biosynthesis. butyryl-CoA synthetase SYN: butyrate-CoA ligase.

Buzzard
Thomas, English physician, 1831–1919. See B. maneuver.

Buzzi
Fausto, coworker of Ernst Schweninger. See Schweninger-B. anetoderma.

Byars
Louis T., 20th century U.S. surgeon, (1906-) See B. flap.

Byler
Amish kindred in the U.S. See B. disease.

bypass (bi′pas)
1. A shunt or auxiliary flow. 2. To create new flow from one structure to another through a diversionary channel. SEE ALSO: shunt. aortocoronary b. SYN: coronary artery b.. aortoiliac b. an operation in which a vascular prosthesis is united with the aorta and iliac artery to relieve obstruction of the lower abdominal aorta, its bifurcation, and the proximal iliac branches. aortorenal b. a vascular prosthesis of synthetic material, autologous tissue, or heterologous tissue that circumvents and obstruction of the renal artery. bowel b. SYN: jejunoileal b.. cardiopulmonary b. diversion of the blood flow returning to the heart through a pump oxygenator (heart-lung machine) and then returning it to the arterial side of the circulation; used in operations upon the heart to maintain extracorporeal circulation. coronary artery b. conduit, usually a vein graft or internal mammary artery, surgically interposed between the aorta and a coronary artery branch to coronary shunt blood beyond an obstruction. SYN: aortocoronary b.. extra-anatomic b. a vascular b. that does not conform to the preexisting anatomy. extracranial-intracranial b. a vascular shunt created by the anastomosis of an extracranial vessel to an intracranial vessel, usually, the superficial temporal artery to a cortical branch of the middle cerebral artery. femoropopliteal b. a vascular prosthesis of synthetic material, autologous tissue, or heterologous tissue that circumvents an obstruction in the femoral artery. gastric b. high division of the stomach, anastomosis of the small upper pouch of the stomach to the jejunum, and closure of the distal part of the stomach that is retained; used for treatment of severe obesity. jejunoileal b. anastomosis of the upper jejunum to the terminal ileum for treatment of severe obesity. SYN: bowel b., jejunoileal shunt. left heart b. any procedure that shunts blood returning from the pulmonary circulation to the systemic circulation without passing through the left heart. This is utilized during some cardiac surgery and experimentally during severe left heart failure or cardiogenic shock. partial ileal b. division of the small intestine approximately 100 cm proximal to the ileocecal valve, closure of the distal end, and anastomosis of the proximal end to the cecum. right heart b. introduction of a circuit shunting blood from the venae cavae around the right atrium and ventricle and directly into the pulmonary artery.

byssinosis (bis-i-no′sis)
Obstructive airway disease in people who work with unprocessed cotton, flax, or hemp; caused by reaction to material in the dust and thought to include endotoxin from bacterial contamination. Sometimes called &dquor;Monday morning asthma&dquor; since patients improve when away from work on the weekend. SYN: cotton-dust asthma, cotton-mill fever, mill fever. [G. byssos, flax, + -osis, condition]

byte
A group of adjacent bits, commonly 4, 6, or 8, operating as a unit for the storage and manipulation of data in a computer.

β-carotene 15,15′-dioxygenase
An enzyme catalyzing the reaction of β-carotene plus O2, producing two retinals. SYN: β-carotene-cleavage enzyme, carotenase.

β-chlorovinyldichloroarsine (klor′o-vi′nil-di-klor′o-ar′sen)
SYN: lewisite.

3β-coprostanol (kop-ros′tan-ol)
SYN: coprosterol.

β-corticotropin
Acid- or pepsin-degraded β-corticotropin. SYN: corticotropin (2) .

β-cortol
α-Cortol with a 20β-OH group; the 5β enantiomer of β-allocortol, found in urine.

β-cortolone
α-Cortolone with a 20β-OH group; the 5β enantiomer of β-allocortolone, found in urine.

β-cystathionase
SYN: cystathionine β-lyase.

β,β-dimethylcysteine (di-meth-il-sis′te-en)
SYN: penicillamine.

β-farnesene
One of the two isomers (trans) that occurs in the alarm pheromone of some aphids and also in various essential oils.

β-fructofuranosidase (fruk′to-foor-a-no-sid′as, fruk-)
β-h-Fructosidase;an enzyme hydrolyzing β-d-fructofuranosides and releasing free d-fructose; if the substrate is sucrose, the product is d-glucose plus d-fructose (invert sugar); invert sugar is more easily digestible than sucrose. SYN: invertase, invertin, saccharase.

β-galactosidase (ga-lak′to-si′das)
An enzyme that hydrolyzes the beta galactoside linkage in lactose-producing glucose and galactose; also hydrolyzes the chromogenic substrate IPTG (isopropylthiogalactoside) and thus is used as an indicator of fused genes and gene expression.

β-d-galactosidase
A sugar-splitting enzyme that catalyzes the hydrolysis of lactose into d-glucose and d-galactose, and that of other β-d-galactosides; it also catalyzes galactotransferase reactions; a deficiency of β-d-galactosidase leads to problems in the intestinal digestion of lactose; used in the production of milk products for adults who do not have the intestinal enzyme; a defect of one isozyme of β-d-galactosidase is associated with Morquio syndrome type B. Cf.:lactase persistence, lactase restriction. SYN: lactase.

β-galactosylceramidase
An enzyme that participates in the catabolism of certain ceramides; a deficiency of β-galactosylceramidase is associated with Krabbe disease.

β-glucocerebrosidase (gloo′ko-ser′e-bro-sid-as)
An enzyme that hydrolyzes β-glucosides in cerebrosides; a deficiency of this enzyme results in Gaucher disease.

β-d-glucosidase
A glucohydrolase similar to α-d-glucosidase, but attacking β-glucosides and releasing β-d-glucose. SYN: amygdalase, cellobiase, gentiobiase.

β-d-glucuronidase (gloo-koo-ron′i-das)
An enzyme catalyzing the hydrolysis of various β-d-glucuronides, liberating free d-glucuronic acid and an alcohol; a deficiency of this enzyme is associated with Sly syndrome. SYN: glusulase, glycuronidase.

β-HCG
SYN: chorionic gonadotropin.

β-hydroxybutyric acid
SYN: 3-hydroxybutyric acid.

β-hydroxyisobutyric acid (hi-droks′e-i-so-byu-ter-ik)
An intermediate in the degradation of l-valine.

β-hydroxy-β-methylglutaryl-CoA (HMG-CoA)
A key intermediate in the synthesis of ketone bodies, of steroids, and of farnesyl and geranyl derivatives. SYN: 3-hydroxy-3-methylglutaryl-CoA. β-hydroxy-β-methylglutaryl- lyase an enzyme, found primarily in liver and rumen epithelium that catalyzes the formation of acetyl-CoA and acetoacetate from β-hydroxy-β-methylglutaryl-CoA; a key step in ketogenesis; a deficiency of this enzyme leads to episodes of severe metabolic acidosis without ketosis. β-hydroxy-β-methylglutaryl- reductase an enzyme that catalyzes the rate-limiting step of cholesterol biosynthesis: β-hydroxy-β-methylglutaryl-CoA + 2NADPH + 2H+ → (R)-mevalonate + 2NADP+ + CoA. β-hydroxy-β-methylglutaryl- synthase an enzyme in mitochondria that catalyzes the reaction of acetyl-CoA with acetoacetyl-CoA and water to form (S)-β-hydroxy-β-methylglutaryl-CoA and coenzyme A, a step required for both ketogenesis and steroidogenesis to occur.

β-hydroxypropionic acid (hi-drok′se-pro′pe-on′ik)
A minor intermediate in propionate and methylmalonate metabolism. See β-hydroxypropionic aciduria.

β-hydroxypropionic aciduria
Elevated levels of β-hydroxypropionic acid in the urine; seen in defects in methylmalonic acid and propionate metabolism, as well as in ketotic hyperglycinemia syndrome.

3β-hydroxysteroid sulfatase (hi-drok′se-ster′oid)
An enzyme, found in most mammalian tissues, that is capable of hydrolyzing the sulfate ester bonds of a variety of sulfated sterols; a deficiency of this enzyme will result in X-linked ichthyosis.

β-ketoacyl-ACP reductase (ke-to-as′il)
SYN: 3-oxoacyl-ACP reductase.

β-ketoacyl-ACP synthase
SYN: 3-oxoacyl-ACP synthase.

β-ketohydrogenase (ke-to-hi′dro-jen-as)
SYN: 3-hydroxyacyl-CoA dehydrogenase.

β-ketoreductase (ke′to-re-duk′tas)
SYN: 3-hydroxyacyl-CoA dehydrogenase.

β-ketothiolase (ke-to-thi′o-las)
SYN: acetyl-CoA acyltransferase.

β-lactam
A class of broad-spectrum antibiotics that are structurally and pharmacologically related to the penicillins and cephalosporins.

β-lactamase (lak′ta-mas)
An enzyme produced by many species of bacteria that disrupts the four-membered β-lactam ring of penicillin and cephalosporin groups of antibiotics, destroying their antimicrobial activity. The ability of an organism to produce a β-lactamase may be chromosomal and constitutive or a plasmid-associated acquired property. SYN: cephalosporinase, lactamase, penicillinase (1) .

β-mercaptoethanol
SYN: 2-mercaptoethanol.

9-β-d-ribofuranosyladenine (ri′bo-foor-an′o-sil-ad′e-nen)
SYN: adenosine.

1-β-d-ribofuranosylcytosine (ri′bo-foor-an′o-sil-si′to-sen)
SYN: cytidine.

9-β-d-ribofuranosylguanine (ri′bo-foor-an′o-sil-gwah′nen)
SYN: guanosine.

9-β-ribofuranosylpurine (ri′bo-foo-ran′o-sil-poo′ren)
SYN: nebularine.

1-β-d-ribofuranosyluracil (ri′bo-foor-an′o-sil-ur′a-sil)
SYN: uridine.

β-sitosterol (si-to-ster′ol)
A phytosterol and anticholesteremic. SYN: cinchol.

β-sulfinylpyruvic acid (sul′fi-nil-pi-roo′vik)
An intermediate product of l-cysteine catabolism in mammalian tissue.

β-T
Symbol for β-tocopherol.

β-thionase (thi′o-nas)
SYN: cystathionine β-synthase.

β-tocopherol (β-T)
A lower homolog of α-tocopherol that contains one less methyl group in the aromatic nucleus and is less active biologically; accompanies α-tocopherol and γ-β-tocopherol.

β-tyrosinase
SYN: tyrosine phenol-lyase.




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