Sidney B. Rosalki

Serum γ-glutamyl transpeptidase activity in alcoholism

Abstract Serum γ-glutamyl transpeptidase (GGTP) activity was elevated in three-quarters of seventy-six anicteric alcoholics or heavy drinkers, 44 of whom (58%) were ambulant out-patients without clinical evidence of liver disease. Transaminase elevation was observed in less than one third, and alkaline phosphatase elevation in less than one tenth. GGTP was the only enzyme elevated in the group classified as heavy drinkers rather than alcoholics. GGTP determination is methodologically simple ; its measurement is considered to be a sensitive and highly specific test for the detection of liver cell injury in the suspected alcoholic and to be superior to transaminase determination for this purpose.

Gamma-glutamyl transpeptidase.

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 drugs 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.

Activation by pyridoxal 5-phosphate of aspartate transaminase in serum of patients with heart and liver disease.

When aspartate transaminase activity in serum is increased, pyridoxal 5-phosphate addition produces more pronounced activation of post-myocardial infarct sera than of sera from patients with chronic liver disease. Possible explanations for this are considered. Routine pre-incubation of sera with pyridoxal phosphate prior to aspartate transaminase determination is recommended.

Standardisation of isoenzyme assays with special reference to lactate dehydrogenase isoenzyme electrophoresis.

The many factors that may be involved in the standardisation of isoenzyme assays are illustrated by reference to lactate dehydrogenase separation by electrophoresis and isoenzyme demonstration by tetrazolium staining. Some proposals are made for a standardised lactate dehydrogenase isoenzyme procedure by this technique.

Transient presence in serum of an atypical alkaline phosphatase

Abstract We report the transient presence in serum of a rapidly-migrating, heat-labile, phenylalanine-resistant, homoarginine-sensitive abnormal alkaline phosphatase in a patient with mild gastro-intestinal disease. The features of the enzyme are distinct from those of other reported phosphatases. Unlike most abnormal phosphatases the enzyme was not associated with neoplasia.

A New Colorimetric Procedure for Blood Alcohol Determination

Abstract A new colorimetric procedure for blood alcohol determination is described. Blood proteins are precipitated, and the protein-free supernatant incubated with nicotinamide-adenine dinucleotide (NAD), alcohol dehydrogenase (ADH), nitro blue tetrazolium (nitro BT) and phenazine methosulphate (PMS). Ethanol in the sample reduces the NAD, and the reduced NAD so formed reduces nitro BT to a coloured formazan, PMS serving as an intermediate electron carrier. The reaction is allowed to proceed to completion and colour formation quantitatively relates to sample alcohol concentration. An ethanol standard of known concentration is included with each batch of determinations and sample alcohol concentration calculated from this. The method permits the examination of large numbers of samples with rapidity and precision and without the need for specialized apparatus. Comparison with an ultra-violet enzymatic procedure for blood alcohol determination, gave excellent agreement.

Separation of adenylate kinase isoenzymes on cellulose acetate membrane

Abstract A method is described for the electrophoretic separation and staining of adenylate kinase isoenzymes on cellulose acetate membrane. A discontinuous buffer system is used for separation, and separation and staining can be completed in one hour. The procedure has proved valuable in the study of human red cell adenylate kinase genetic polymorphism.