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Biomedical subjects

P R Beck

Publications and source records attributed to P R Beck.

28 records · Page 2Linked to original sources
PubMed1978

Influence of detergents and organic solvent extraction on human gamma-glutamyltransferase activity.

Human serum and urinary gamma-glutamyltransferase (gamma-GT) have been found to react differently towards the detergents Triton X-100 and sodium lauryl sulphate (SDS). Serum gamma-GT was virtually unaffected by Triton X-100 at a concentration of 5% whereas urinary gamma-GT was 10-15% activated under similar conditions. There was a 100-fold difference in the response of serum and urinary gamma-GT to SDS. The enzyme activity in urine was completely destroyed by 0.02% SDS, whereas it required 2.0% to destroy the serum enzyme. These latter differences, however, were found to result from the environments of the serum and urinary enzyme rather than to intrinsic factors within the molecule. Extraction of serum gamma-GT from normal individuals with n-butanol resulted in little or no loss of activity from the aqueous phase, whereas more than 30% activity was lost from normal urines. Extraction using various mixtures of butanol and di-isopropyl ether (DIPE) produced largely similar results, except that 25% DIPE: 75% butanol mixture produced a marked loss of activity from serum. It is suggested that gamma-GT activity in human body fluids may be dependent on the presence of a lipid fraction.

Butanols↗
PubMed1978

Butanol extraction of serum and urinary gamma-glutamyltransferase and its application in clinical diagnosis.

Gamma-glutamyltransferase (gamma-GT) activity was measured in serum and urine before and after extraction with n-butanol. Residual gamma-GT activity after extraction of normal serum with butanol was more than 75%, whereas for normal urine the figure was less than 68%. The loss of activity from urine was not affected by prior dialysis, and the stabilisation which resulted from adding bovine serum albumin at a concentration of 40 g/l did not approach the residual activity with normal serum. In patients with a variety of renal diseases, residual gamma-GT activity in the urine after butanol extraction was inversely correlated with the creatinine clearance. Butanol extraction was performed on serum samples from 182 patients with a variety of diseases. Eighty-one per cent of patients with elevated gamma-GT activities caused by hepatobiliary disease had an increased loss of activity after butanol extraction. By contrast, only 34% of patients with increases gamma-GT activities in whom there was no clinical or other biochemical evidence of hepatic disease, had increased loss of gamma-GT activity after butanol. The reasons for differences between urinary and serum gamma-GT in response to butanol, and the implications in interpreting serum gamma-GT activities are discussed.

Butanols↗
PubMed1977

Aminoglycoside antibiotics and renal function: changes in urinary gamma-glutamyltransferase excretion.

The urinary excretion of the renal proximal tubular enzyme, gamma-glutamyltransferase (gamma-GT), has been studied in 41 patients receiving tobramycin, gentamicin or streptomycin for a variety of infections. All patients receiving tobramycin or gentamicin have shown increased excretion of gamma-GT in the urine. Only 46% of those receiving streptomycin have shown an increase in gamma-GT excretion and this is of a lesser degree. A change in creatinine clearance which could only be explained by antibiotic administration was detected in three patients (2 on gentamicin, 1 on streptomycin). The degree of elevation of urinary gamma-GT activity was greater when the initial creatinine clearance was lower, and it is therefore suggested that those patients with pre-existing renal dysfunction should be monitored particularly carefully for signs of nephrotoxicity from these antibiotics. Urinary gamma-GT is a useful enzyme in the investigation of renal drug effects.

Adult↗
PubMed1976

Effect of tobramycin on urinary gamma-glutamyltransferase activity: Studies in a case of renal carcinoma.

Gamma-Glutamyltransferase activity was studied in a man presenting with recurrent septicemia owing to pyonephrosis and renal carcinoma. Increased activity in the urine was ascribable to administration of the aminoglycoside antibiotic, tobramycin. That the renal carcinoma did not contribute to the increased values was confirmed by homogenization and enzyme histochemistry of the tumor. Although the activity of this enzyme in serum was greater than normal, this persisted postoperatively, and thus was not related to the renal carcinoma.

Aged↗
PubMed1975

A stabilising factor for gamma-glutamyl transpeptidase in urine.

Urinary gamma-glutamyl transpeptidase (gamma-GT) has been found to be stable when stored at room temperature and 4 degrees C. Activity is lost rapidly when urine is frozen but prior dialysis will prevent this loss. Urea is the major factor responsible for the loss of activity; albumin is protective at concentrations of 6 g/l or more. A factor of 10 000-30 000 molecular weight which will prevent the loss of urinary gamma-GT activity on freezing has been found in serum and urine; it has high potency in serum and in urine from patients with chronic renal failure, but only low potency in normal urine. Its nature is unknown but it is heat stable.

Albumins↗
PubMedDate not supplied

Folic acid and total parenteral nutrition.

The stability of folic acid in a variety of solutions used for parenteral nutrition has been determined over a 2-wk period. Provided that the acidity of the solution remains above pH 5.0 the folate, in the concentrations usually used for parenteral nutrition, will remain stable in solution, and all of the folate added to the solution will be delivered to the patient. The applicability of this in vitro work to a group of patients requiring parenteral nutrition was assessed, in order to determine a suitable dose. A dose of 0.2 mg of folic acid daily was inadequate to meet the requirements of these patients. In contrast a dose of 1.2 mg daily for 7 days was sufficient to cause an increase in the serum folate concentration.

Dose-Response Relationship, Drug↗