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Biomedical subjects

D C May

Publications and source records attributed to D C May.

At least 19 recordsLinked to original sources
PubMed1992

Plastic surgeons' opinions of facial surgery for individuals with Down syndrome.

Plastic surgeons from Los Angeles and New York (N = 182) were surveyed on their opinions of facial plastic surgery for individuals with Down syndrome. Of the 100 respondents, 88 were familiar with the procedures, and 24 had performed the surgery. The surgeons indicated the circumstances for recommending the surgery, who would be required to give consent, the degree to which they thought individuals with Down syndrome could understand the nature of the surgery, and their opinion of the degree of discomfort associated with the surgery.

Attitude of Health Personnel↗
PubMed1988

Rapid binding of guanosine 5'-O-(3-thiotriphosphate) to an apparent complex of beta-adrenergic receptor and the GTP-binding regulatory protein Gs.

When reconstituted phospholipid vesicles that contain purified beta-adrenergic receptors and the GTP-binding regulatory protein Gs were preincubated with agonist before the addition of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), the typical receptor-stimulated GTP gamma S binding reaction was preceded by an even more rapid burst of GTP gamma S binding. This burst was studied in detail at 0 degree C. The rate of the burst was second order in nucleotide and Gs [k assoc approximately 2 X 10(7) (M.min)-1], consistent with diffusion-controlled binding. The magnitude of the burst was always less than the number of receptors present and was roughly linear with receptor number when similarly prepared vesicles were compared. There was no obvious quantitative correlation between the burst and the amount of Gs. The species that gave rise to the burst formed with t1/2 approximately 15 min at 0 degree C in the presence of agonist and decayed by approximately 3 min upon addition of antagonist or detergent. Formation and decay of this species was much faster at at 30 degrees C. The data suggest that a complex of agonist, receptor, and Gs that is primed for the rapid binding of guanine nucleotide can form and be analyzed in reconstituted vesicles.

Animals↗
PubMed1987

In vivo induction and reversal of nitroglycerin tolerance in human coronary arteries.

The mechanism by which tolerance to the clinical effects of organic nitrates develops has not been elucidated. This study was done to determine whether an intravenous infusion of nitroglycerin induces tolerance in the coronary vascular bed and whether such tolerance is reversed by the sulfhydryl-group donor N-acetylcysteine. We studied 19 subjects--17 with coronary artery disease and 2 without it--who had a mean age (+/- SD) of 54 +/- 9 years. Coronary sinus blood flow, which approximates blood flow to the left ventricle, was measured before and during intracoronary injections of nitroglycerin (10, 25, 50, and 100 micrograms). The patients then received a 24-hour intravenous infusion of saline (n = 7) or of nitroglycerin, 45 +/- 13 micrograms per minute (n = 12), after which the responses of coronary sinus flow to the same doses of intracoronary nitroglycerin used earlier were measured. In the seven patients given saline, the four doses of intracoronary nitroglycerin caused similar percentage increases in coronary sinus flow before and after the saline infusion. In the 12 patients given intravenous nitroglycerin, the four intracoronary doses caused percentage increases in coronary flow before the infusion of 30 +/- 9, 35 +/- 14, 41 +/- 12, and 52 +/- 15, respectively. After the infusion, the same doses of nitroglycerin caused smaller (P less than 0.05) percentage increases (16 +/- 6, 21 +/- 11, 23 +/- 12, and 27 +/- 11, respectively), indicating the development of partial tolerance. Subsequently, 7 of the 12 patients received N-acetylcysteine, after which intracoronary nitroglycerin caused percentage increases in coronary sinus flow similar to the values measured before the intravenous nitroglycerin was given (34 +/- 13, 32 +/- 8, 38 +/- 11, and 44 +/- 16, respectively). We conclude that the coronary vasodilator effect of nitroglycerin is attenuated by an intravenous infusion of nitroglycerin (that is, partial tolerance develops) and that tolerance to the agent can be reversed by administration of the sulfhydryl-group donor N-acetylcysteine. The mechanism by which N-acetylcysteine reverses tolerance will require further investigation.

Acetylcysteine↗
PubMed1986

Chronic sclerosing glomerulopathy (heroin-associated nephropathy) in intravenous T's and Blues abusers.

The intravenous (IV) use of pentazocine (Talwin) and tripelennamine (pyribenzamine) has become a major form of drug abuse seen in the midwestern United States. Complications of this abuse have included psychotic reactions, acute pulmonary insufficiency, convulsions, and various infections. We have observed three patients in whom the IV use of these agents was associated with the nephrotic syndrome and renal histopathologic findings similar to that reported in heroin addicts with the so-called "heroin-associated nephropathy." Percutaneous renal biopsy demonstrated focal to diffuse segmental or global glomerulosclerosis by light microscopy. Electron microscopy revealed glomerular visceral epithelial cell foot process effacement and microvillus formation. Immunofluorescent studies were negative in the two patients studied. One patient presented in renal failure, and two others progressed to renal failure within 3 years of diagnosis. We suggest the term opiate nephropathy for this lesion in narcotics users, indicating its potential occurrence in non-heroin-using drug addicts.

Adult↗
PubMed1986

The avian beta-adrenergic receptor: primary structure and membrane topology.

Partial amino acid sequence information allowed the isolation of cDNA clones encoding the turkey erythrocyte beta-adrenergic receptor. Antisera raised against synthetic peptides encoded by the cDNA crossreacted with the purified receptor and appropriate tryptic fragments, confirming the identity of the cDNA. The receptor is composed of 483 amino acids and has a molecular mass of 54 kDa. Its sequence suggests that it is arranged predominantly in seven membrane-spanning sequences and a long cytoplasmic carboxyl-terminal domain. The extracellular amino-terminal domain contains a consensus sequence for N-glycosylation. The beta-adrenergic receptor displays overall structural similarity and weak sequence homology with rhodopsin. Because both proteins act by regulating GTP-binding proteins, a compact structure based on seven membrane-spanning regions may be a general model for receptors that act on G proteins.

Amino Acid Sequence↗
PubMed1986

Research on effects of color reversal on the visual perceptual and visuomotor performances of spastic cerebral palsied and other exceptional individuals.

Research pertaining to the effects of color-reversal (black and white) on the visual perceptual and visuomotor performances of spastic cerebral-palsied children and other exceptional individuals was examined. In general, evidence to date suggests that spastic cerebral-palsied children show significant improvement in visuomotor and visual perceptual performance with the color-reversal of the standard black-on-white figure-ground relationship in stimulus and response materials of standardized tests.

Brain Damage, Chronic↗
PubMed1985

Reconstitution of catecholamine-stimulated adenylate cyclase activity using three purified proteins.

beta-Adrenergic receptors, the GTP-binding regulatory protein that stimulates adenylate cyclase (Gs), and adenylate cyclase were each purified and reconstituted into unilamellar vesicles composed of phosphatidylethanolamine and phosphatidylserine (3:2, w/w). The molar ratio of receptor:Gs:adenylate cyclase was estimated to be about 1:10:1. Adenylate cyclase activity in the vesicles was stimulated up to 2.6-fold by beta-adrenergic agonists. Stimulation was dependent on the presence of guanine nucleotide, displayed appropriate beta-adrenergic selectivity and stereoselectivity for agonists, and was blocked appropriately by beta-adrenergic antagonists. Therefore, while additional proteins may modulate adenylate cyclase activity in native membranes, these results show that these three proteins are sufficient for the expression of hormone-stimulated adenylate cyclase.

Adenylyl Cyclases↗
PubMed1985

Evaluation of acute scrotum pain with testicular scanning.

Emergency room physicians frequently are faced with the evaluation of the patient with acute testicular pain. The rapid differentiation between testicular torsion and acute epididymitis is necessary although frequently difficult due to an atypical presentation. We describe four patients with testicular pain in whom testicular scanning provided useful adjunctive information regarding diagnosis. This technique clearly differentiates acute torsion, acute epididymitis, testicular rupture, and missed torsion with abscess formation, prompting appropriate therapy in each case. Testicular scanning provides a rapid, noninvasive method to assist in the evaluation of testicular pain.

Adolescent↗
PubMed1985

Effects of figure-ground reversal on the visual-perceptual and visuo-motor performances of cerebral palsied and normal children.

Individuals with brain damage often encounter visual perceptual and visuo-motor difficulties. Studies have indicated an improvement in exceptional individuals' performances when the colors of figure-ground materials were reversed. Effects of reversals were studied for spastic cerebral palsied and normal children's scores on the Developmental Test of Visual-motor Integration and the Motor-free Visual Perception Test. Normal children performed better than the cerebral palsied children on all tests; the cerebral palsied children performed best on the reversed-format Motor-free Visual Perception Test. Reversal affected neither group's scores on visual-motor integration.

Cerebral Palsy↗
PubMed1984

Acute carbamazepine intoxication: clinical spectrum and management.

Carbamazepine is an anticonvulsant drug in widespread use for the treatment of tonic-clonic and temporal lobe seizure disorders. Acute intoxication with this agent results in both neurologic and cardiovascular dysfunction. Neurologic manifestations may range from mild ataxia to profound coma with respiratory failure and are correlated with the plasma drug level. Cardiovascular effects appear primarily as conduction system disturbances. Treatment of carbamazepine overdose consists of aggressive orogastric lavage followed by activated charcoal administration with catharsis. Continuous electrocardiographic monitoring and close observation are necessary until plasma carbamazepine levels fall to therapeutic anticonvulsant levels. In cases of severe intoxication with respiratory failure and prolonged intubation, charcoal hemoperfusion has been reported to result in rapid improvement.

Acute Disease↗
PubMed1984

Acute synovitis caused by an organism of the Rhodochrous taxon.

A 36-year-old man with systemic lupus erythematosus developed synovitis of the right wrist caused by an organism of the Rhodochrous taxon. The capacity of this pathogen to produce a granulomatous inflammatory reaction in human tissues is discussed. The isolate was sensitive to chloramphenicol, gentamicin, carbenicillin and colistin in in-vitro tests and the infection responded promptly to treatment with chloramphenicol.

Actinomycetales↗
PubMed1983

Effect of probenecid on dyphylline elimination.

Dyphylline is a methylxanthine bronchodilator with such a short a biologic t 1/2 that development of practical dosing regimens has been difficult. Because its rapid renal elimination suggests active secretion, the effect of 1 gm probenecid on single-dose elimination kinetics of dyphylline was determined. Twelve subjects (six male, six female) participated in a crossover design. Subjects were their own controls and received dyphylline, 20 mg/kg orally, alone and after probenecid. The dyphylline t 1/2 increased from 2.57 +/- 0.45 to 4.88 +/- 1.2 hr, whereas the elimination rate constant decreased from 0.276 +/- 0.056 to 0.150 +/- 0.037 hr-1 after probenecid. There was no significant change in the dyphylline apparent volume of distribution. Dyphylline total body clearance fell from 173 +/- 20 to 95 +/- 12 ml/kg . hr. The combined use of these drugs may lead to a practical dyphylline dosage schedule in aminophylline-hypersensitive patients or those incapacitated by theophylline gastrointestinal side effects.

Chromatography, High Pressure Liquid↗
PubMed1982

Effects of cimetidine on caffeine disposition in smokers and nonsmokers.

The absorption, distribution, and elimination of caffeine, 2 mg/kg by mouth, were evaluated in six smokers and six nonsmokers before and on the fourth day of administration of cimetidine, 300 mg by mouth every 6 hr. Caffeine absorption, assessed by the maximal serum caffeine concentration (C max) and the time to reach Cmax (t max), was very rapid relative to elimination. The total body clearance (TBC) of caffeine was higher (2.49 +/- 0.35 and 1.59 +/- 0.19 ml/kg/min, P less than 0.05) and the elimination half-life (t1/2) shorter (190 +/- 15 and 276 +/- 30 min, P less than 0.05) in smokers than nonsmokers, but Cmax, tmax, and the apparent volume of distribution (Vd, app) did not differ (P greater than 0.05). Cimetidine decreased the TBC of caffeine by 31% (to 1.73 +/- 0.28 ml/kg/min, P less than 0.05) and by 42% (to 0.92 +/- 0.11 ml/kg/min, P less than 0.01) in smokers and nonsmokers. The increases in t1/2 were 45% (to 276 +/- 25 min, P less than 0.05) and 96% (to 542 +/- 123 min, P less than 0.05). Cmax, tmax, and Vd, app were unaffected by cimetidine. Caffeine induced similar slight increases in blood pressure and pulse rate in smokers and nonsmokers both before and during cimetidine dosing.

Adult↗