Determination of Serum γ-Glutamyl Transpeptidase Activity and its Clinical Applications
TL;DR: The L-y-g1utamyl-p-nitroanilide concentration of the substrate and pH chosen were those suggested by Orlowski (1965) and this concentration was found to be optimal, but because of the lower volume of serum in the incubation mixture the final concentration in the reaction mixture is slightly higher (5.6 mmol/I instead of 5·0 mmol/l).
Abstract: The L-y-g1utamyl-p-nitroanilide concentration of the substrate (6.25 mmol/l) and pH (9'0) chosen were those suggested by Orlowski (1965). However, because of the lower volume of serum in the incubation mixture the final concentration of L-yglutamyl-p-nitroanilide in the reaction mixture is slightly higher (5.6 mmol/I instead of 5·0 mmol/l). This concentration was found to be optimal. Optimal enzyme activity was observed over the pH range 8.0-8.5, and at pH 9.0 only 90% of maximal activity was observed. The original pH recommended was, however, retained because of the greater tendency of the substrate to precipitate on standing at lower pH levels. Glycylglycine, used as glutamyl group acceptor (Kulhanek and Dimov, 1966), yielded optimal activity at a substrate concentration of 0.05 mol/l (final concentration in reaction mixture, 0.045 molfl) and this concentration was adopted. The addition of magnesium chloride at a final concentration of 10 mmol/l was without effect, but at 100 mmol/l 6% inhibition was observed. Calcium chloride reduced activity by 6 % at 10 mrnol/l and by 31% at 100 rnrnol/I, Sodium chloride and azide were without effect at both concentrations. Manganese chloride, and zinc acetate or sulphate at a final concentration of 10 mmol/l gave rise to turbidity with the substrate. photometer is available, the molar extinction coefficient of p-nitroaniline may be used for the calculation of G.G.T.P. activity. Under the test conditions described, the O.D. of a p-nitroaniline solution of concentration 100 pomol/l corresponds to that yielded by a serum of G.G.T.P. activity 200 i.u./l. With this colorimeter O.D. increased linearly with increasing p-nitroaniline concentration only up to 100 pomol/l. Using other instruments, however, linearity extended to higher concentrations.
Citations
More filters
TL;DR: Serum γ-glutamyl transpeptidase activity was elevated in three-quarters of anicteric alcoholics or heavy drinkers, 44 of whom (58%) were ambulant out-patients without clinical evidence of liver disease.
412 citations
TL;DR: The present study suggested that naringenin may be beneficial in ameliorating the cadmium-induced oxidative damage in the liver of rats.
310 citations
Cites methods from "Determination of Serum γ-Glutamyl T..."
...Gamma glutamyl transferase (GGT) activity was determined by the method of Rosalki et al. (1970) using g-glutamyl-p-nitroanilide as substrate....
[...]
TL;DR: Poult villus size and area were smaller and mucosal enzyme activity was lower than that found in broilers and this may explain the initial slower growth rate in poults.
286 citations
TL;DR: This chapter discusses the measurement of the serum γ-glutamyl transpeptidase (GGTP) in the clinical laboratory and its application to diagnosis.
Abstract: Publisher Summary This chapter discusses the measurement of the serum γ-glutamyl transpeptidase (GGTP) in the clinical laboratory and its application to diagnosis. The enzyme GGTP catalyzes the transfer of γ-glutamyl groups from γ-glutamyl peptides to other peptides, to L-amino acids, and to water. The possible biological functions of GGTP include participation in peptide–nitrogen storage, in protein synthesis, in the regulation of tissue glutathione levels, and in the amino acid transport across cell membranes. The majority of GGTP determination procedures utilize Tris as buffer and γ-glutamyl p-nitroanilide as substrate. The automated p-nitroanilide method for the GGTP determination utilizes a continuous flow technique at 37°C using the Autoanalyzer II. The GGTP determination is of limited value for the diagnosis of myocardial infarction because of the high incidence of false positive and false negative values. The incidence and degree of plasma GGTP changes are correlated with a drug's ability to promote the hepatic enzyme induction. Enzyme changes may be dose or duration dependent, and individuals may show variation in enzyme changes consequent upon genetic variations in drug metabolism.
285 citations
TL;DR: These conventional tests are widely available and relatively inexpensive, and while having limited sensitivity and specificity in detection of excessive drinking, they also provide valuable data on complications of drinking, comorbid conditions that may be affected by drinking and, in some cases, prognosis.
Abstract: Aims The blood tests used traditionally as markers of excessive drinking are the liver enzymes, gamma glutamyltransferase (GGT), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and the red blood cell volume (mean corpuscular volume; MCV). Here we review the nature of these markers’ association with alcohol use, their practical application in detecting, assessing or monitoring drinking and increases in understanding of these markers in the past 10 years. Design Articles were identified via Medline search and perusal of bibliographies. Findings The conventional markers have imperfect sensitivity and specificity, but have an added clinical role in the detection of complications of drinking, and of comorbid conditions that may increase risk of drinking. GGT may in part be a marker of the oxidative stress associated with ethanol metabolism. Markers are more likely to be elevated in those aged more than 30 years and in regular drinkers with a longer drinking history. The markers may be useful in opportunistic case finding, in motivating patients to change drinking and in monitoring treatment response. Increased prevalence of obesity and hepatitis C must be considered in interpretation of liver enzyme results. The liver enzymes are prognostic indicators for several medical conditions and for mortality. Conclusions These conventional tests are widely available and relatively inexpensive. While having limited sensitivity and specificity in detection of excessive drinking, they also provide valuable data on complications of drinking, comorbid conditions that may be affected by drinking and, in some cases, prognosis.
280 citations
References
More filters
9,424 citations
TL;DR: The purpose of this article is to describe a few statistical tools and to illustrate how these tools may be useful in the practice of medicine.
Abstract: PRACTICING PHYSICIANS and statisticians may not seem to have many mutual interests, but perhaps they have more in common than is apparent at first. The purpose of this article is to describe a few statistical tools and to illustrate how these tools may be useful in the practice of medicine. As a starting point, consider a fairly frequently encountered medical problem, diabetes mellitus. According to some physicians, they believe that diabetics are best maintained at slightly elevated blood-glucose levels, but others feel that they should be maintained within limits of clinical normality. Which group is right or are they both right? And what is clinical normality and how is it determined? Suppose we consider the question of clinical normality first, partly because it is relatively easy to discuss and partly because it is a portion of the problem of maintaining diabetics in control. Normal Values According to one textbook, 1
298 citations
TL;DR: Differences are indicated between the action of serum on α-ketobutyrate and its action on pyruvate and that of crystalline lactic dehydrogenase.
Abstract: DURING the course of investigations into serum transaminase activities1, it was observed that α-ketobutyrate (2-oxobutanoate) underwent enzymic reduction in the presence of serum and reduced diphosphopyridine nucleotide. At the time this was interpreted as being due to serum lactic dehydrogenase because a commercial sample of crystalline lactic dehydrogenase prepared from rabbit skeletal muscle reduced α-ketobutyrate almost as readily as its normal substrate, pyruvate2. Further work, however, has indicated differences between the action of serum on α-ketobutyrate and its action on pyruvate.
219 citations
121 citations
TL;DR: A colorimetric method for the assay of γ-glutamyl transpeptidase activity in serum and serous fluids using a synthetic substrate, N-(dl-γ-glUTamyl) aniline, is described, based upon the measurement of anilines liberated by the enzymatic cleavage of the substrate.
65 citations