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Biomedical subjects

P Hayden

Publications and source records attributed to P Hayden.

18 recordsLinked to original sources
PubMed1989

Diabetes mellitus and periodontal disease in an Irish population.

The prevalence of periodontitis was studied in a population of 157 insulin dependent diabetes mellitus patients aged 8-78 years attending the outpatients diabetic clinic of a large general hospital in Cork, Ireland. Every third diabetic patient attending the clinic was selected for examination. The dental parameters measured were plaque index (PI), gingivitis index (GI), periodontal pocket depth (PD) and periodontal attachment loss (PAL). Diabetic control was measured by estimating percentage haemoglobin glycolysation (% Hb Alc) known duration of diabetes (KDD) and insulin dependence. It was found that none of the diabetic measurements showed any consistent pattern in relation to any of the periodontal measurements. The findings are in agreement with other studies which suggest that no significant correlation between diabetic parameters and periodontal disease can be demonstrated. When the diabetic patient suffered periodontitis it was due to factors (such as genetic predisposition) other than impaired glucose metabolism.

Adolescent↗
PubMed1987

Diuretic renography in evaluating dilated upper urinary tract in children.

The diuretic renogram provides a previously unavailable noninvasive method for assessing and following urinary tract dilation of diverse cause, and defining true obstruction in children. Technetium-99m-DTPA (diethylenetriaminepentaacetic acid) is injected intravenously and a posteriorly placed gamma scintillation camera used to image the kidneys, ureters, and bladder. Furosemide is subsequently injected to stimulate a diuresis, and the washout pattern of isotope is monitored (time-activity histogram). Nonobstructive, obstructive, and poor renal function patterns were seen. Forty patients with varying degrees of hydroureteronephrosis were evaluated. Tracings were performed serially and compared with the clinical course in time, as well as with pressure flow studies and operative findings. All patients with a nonobstructed diuretic renogram did well, except for 1 boy in whom ureteropelvic obstruction developed later. Difficulty in evaluating the obstructive renogram pattern occurred only in some children with severe (grade V) hydronephrosis. Further standardization of the diuretic renogram with regard to time of diuretic injection, state of patient hydration, and regions of imaging may improve diagnostic accuracy.

Child↗
PubMed1986

The role of glutathione conjugate metabolism and cysteine conjugate beta-lyase in the mechanism of S-cysteine conjugate toxicity in LLC-PK1 cells.

A cell line derived from pig kidney, LLC-PK1, was grown in a culture system in which the cells express morphological and biochemical characteristics of the proximal tubule. This model was used to investigate the mechanism of S-cysteine conjugate toxicity and the role of glutathione conjugate metabolism. LLC-PK1 cells have the degradative enzymes of the mercapturate pathway, and S-(1,2-dichlorovinyl)-L-cysteine and S-(1,2-dichlorovinyl)-L-glutathione are toxic. S-(1,2-Dichlorovinyl)-L-glutathione is not toxic when the cells are pretreated with AT-125, an inhibitor of gamma-glutamyl transpeptidase. The cells respond to a variety of toxic cysteine conjugates. Cysteine conjugate beta-lyase activity is not detectable by standard assays, but can be measured using radiolabeled S-(1,2-dichlorovinyl)-L-cysteine. Pyruvate stimulates the beta-elimination reaction with S-(1,2-dichlorovinyl)-L-cysteine as substrate 2-3-fold. The data suggest that a side transamination reaction regulates the flux of substrate through the beta-elimination pathway; therefore, cysteine conjugate beta-lyase in LLC-PK1 cells may be regulated by transamination, and measurement of lyase activity in some systems may require the presence of alpha-ketoacids. Aminoxyacetic acid blocks both the metabolism of S-(1,2-dichlorovinyl)-L-cysteine to a reactive species which covalently binds to cellular macromolecules and toxicity. Glutathione inhibits the binding of the sulfur containing cleavage fragment to acid insoluble material in vitro. The data provide direct evidence that S-(1,2-dichlorovinyl)-L-cysteine is metabolized to a reactive species which covalently binds to cellular macromolecules, and the binding is proportional to toxicity.

Acetylcysteine↗
PubMed1976

The ability of stutterers and nonstutterers to initiate and terminate phonation during production of an isolated vowel.

This study tested the hypothesis that stutterers have difficulty initiating and terminating phonation independent of the acts of running speech and stuttering. Ten young adult stutterers served as the experimental group. They were matched as a group for age and sex with 10 normal speakers. Subjects from both groups were tested individually. The experimental task required that subjects start and stop phonation as quickly as possible upon hearing each member of a seried of 1000-Hz pure tones appear and then disappear. Subjects' vocalizations were permanently recorded on an optical oscillograph. Results showed that both groups improved (shortened) their voice initiation and termination times from the beginning to the end of the experiment. Typically, however, the stutterers were significantly slower than the control subjects on most of the temporal measures.

Adolescent↗