[Glutathione (author's transl)]

Damage of erythrocytes by activated oxygen generated in hypoxic rat liver

The implication of activated oxygen in the interaction between hypoxic rat liver and circulating erythrocytes was investigated. Reduced species of oxygen generated in hypoxic liver owing to accelerated purine nucleotide degradation via xanthine oxidase initiate alterations of plasma membrane and glutathione system of erythrocytes. Osmotic fragility, hemolysis rate and erythrocytic GSSG:GSH ratio may be considered as appropriate indicators of oxidative load in liver and other tissues. Addition of erythrocytes to the perfusion medium attenuates the GSSG efflux of hypoxic liver from 2.7 +/- 0.5 nmol x g w.w.-1 x min-1 to 1.4 +/- 0.2 nmol x g w.w.-1 x min-1 Thus, circulating erythrocytes protect the liver against oxidative attack.

Cerebrospinal fluid markers of disturbed brain cell metabolism

Reversibly and irreversibly disturbed brain cell metabolism may be monitored in an indirect way by the analyses of enzymes in the CSF according to the hypothesis of cell swelling induced by energy shortage. Adenylate kinase fulfils the criteria for an ideal CSF marker with the exception that it is not organspecific, which necessitates precautions to avoid influence of AK in erythrocytes and serum. When taking such limitating factors into account, AK determinations may be diagnostically useful in combination with radiological and clinical observations. Besides, it is possible that a combination of AK analyses and clinical signs are useful in the prognostication in individual patients suffering from global cerebral ischemia and cerebral infarction.

Cerebrospinal fluid content of adenylate kinase, lactate and glutathione in patients with meningitis

Adenylate kinase activity and lactate concentration were measured in the cerebrospinal fluid (CSF) of 5 patients with bacterial meningitis, of 4 patients with probable bacterial meningitis, and of 18 patients with serous meningitis. Furthermore, for comparison measurements were also performed in CSF of 27 patients with meningism. Concomitantly glutathione was measured in CSF in most of the patients. Significantly higher values of these 3 parameters were found in the CSF of patients with bacterial and probable bacterial meningitis compared with those having serous meningitis and meningism. Adenylate kinase activity and lactate concentration in patients with serous meningitis were significantly higher than in those with meningism. All patients with a clinical diagnosis of meningitis studied so far also displayed an adenylate kinase activity in their CSF. The determination of adenylate kinase, lactate and glutathione levels in CSF might be a useful aid for the diagnosis not only of meningitis but also for the discrimination between bacterial and serous meningitis.

[Enzyme deficiencies of blood cells in bone marrow insufficiency (author's transl]

Numerous enzyme defects-deficiency of pyruvate kinase, phosphofructo-kinase, glocosephosphate isomerase, adenylate kinase, 2,3-diphosphoglycerate mutase and glutathione reductase--in red blood cells have been described to be connected with dyserythropoietic or refractory anemias and panmyelopathies of different origin. These enzyme deficiencies also have been demonstrated in red cells of patients with acute leukemia. Most likely the enzyme deficiencies are acquired and are not important for the origin of anemia or bone marrow insufficiency. Partial derepression of fetal genes, qualitative and quantitative perturbations of genetic expression, and posttranslational variations of the enzyme protein by low molecular factors from plasma, erythrocytes or leukemic cells have been discussed as a reason of enzyme deficiency. The decrease of glutathione reductase deficiency is dependent of FAD deficiency.

Biologically important thiol-disulfide reactions and the role of cyst(e)ine in proteins: an evolutionary perspective

Selected aspects of the reactions of thiols and disulfides are reviewed in an evolutionary context with special emphasis on the implications of the transition from a reducing to an oxidizing atmosphere on the earth. It is argued that thiols were important in prebiotic chemistry and in primitive metabolism but that disulfides, owing to their general instability in a reducing environment, came to be of importance as structural links in proteins only after the transition to an oxidizing atmosphere. The occurrence of glutathione is reviewed and discussed in terms of the role of glutathione in maintaining a reducing intracellular environment. The occurrence of cysteine and cystine in intracellular and extracellular proteins of bacteria and of animals is examined in terms of the redox state of the environment in which the protein functions. Thiol-disulfide changes associated with the dormant state are described and the role of cellular water content in dormancy is discussed. The potential significance of reactions between thiols and products of oxidative metabolism is discussed with special emphasis upon thiol additions to carbonyl and alpha, beta-unsaturated carbonyl groups and their possible role in steroid-receptor interaction.

[Enzyme deficiencies in glycolysis and nucleotide metabolism of red blood cells in nonspherocytic hemolytic anemia (author's transl)]

The detection of enzyme deficiencies in glycolytic and nucleotide metabolism of human red blood cells has enriched the pathophysiological knowledge on the origin of nonspherocytic hemolytic anemias (NSHA). So far for 11 of 13 glycolytic enzymes deficiencies have been described which are connected with alterations of biochemical enzymatic properties. The most frequent enzyme deficiencies are those of GPI and PK. By performance of special electrophoretic techniques genetic studies allow the demonstration of homozygote and double heterozygote defect carriers. Up to now only adenylate kinase and pyrimidine 5' nucleotidase deficiencies have been detected as genetically determined in altered nucleotide metabolism. The metabolic alterations of several enzymopathies have been characterized so well, that the pathophysiological relations between enzyme deficiency and NSHA probably have been found to be a sufficient explanation.