Glutathione metabolism. II. The oxidation and reduction of glutathione in intact erythrocytes

The epidemiology of favism

Favism is a potential obstacle to the use of the fava bean in the development of a locally produced, inexpensive weaning food for the Middle East and North Africa. The purposes of this study were to define the epidemiology of favism, to evaluate the advisability of using the fava bean in a weaning food, and to suggest ways of avoiding or eliminating the toxic factor in the bean. Field observations, locally acquired data, and a literature review suggested that the use of the fava bean in a weaning food would be hazardous, but that the hazard might be overcome by using certain strains of the bean or, more particularly, by using old dried beans. The disease is usually directly related in time to the harvesting and availability of fresh beans, but it is also associated with fresh dried beans. On the basis of the age distribution of the disease, patterns of bean consumption, and local food taboos it appears that the toxic factor is concentrated in the skin of the bean, that it is heat-stable, that in dried beans it decreases with age, and that it crosses into the breast milk of lactating mothers. It also appears that disease expression may be a result of the interaction of several host factors, such as nutritional status and the consumption of other foods. These observations are consistent with the results of laboratory studies, which incriminate vicine, divicine, and DOPA in the etiology of favism.

THE RELATIONSHIP OF HYDROGEN PEROXIDE TO THE INHIBITION OF THE GLYOXALASE ACTIVITY OF INTACT ERYTHROCYTES BY X-RADIATION

The x-irradiation of a dilute suspension of erythrocytes results in a decrease in the glyoxalase activity of the cells as a result of a fall in the reduced glutathione level. The present paper deals with the possible role of H(2)O(2) in this reaction. The addition of intact erythrocytes to physiological saline previously irradiated with 150,000 r or 225,000 r results in a fall in the glyoxalase activity of the cells. The inhibition is prevented by the preincubation of the irradiated saline with catalase and is reversed by the addition of plasma, glucose, adenosine, and inosine to the cell suspension. An inhibition of the glyoxalase activity is also produced by the addition of H(2)O(2) to the suspension of erythrocytes. The inhibitory effect of H(2)O(2) can be prevented and largely reversed by plasma, glucose, adenosine, and inosine. Methylglyoxal is also protective under these conditions. Hydrogen peroxide formed continuously and in low concentrations by enzyme systems appears to be more effective than added H(2)O(2) in inhibiting the glyoxalase system. The inhibition by H(2)O(2)-producing enzyme systems is minimized by the addition of catalase, plasma, glucose, methylglyoxal, and to a lesser extent, by adenosine and inosine, and is accentuated by the addition of sodium azide. The results are discussed in relation to the role of H(2)O(2) and catalase in the toxicity of ionizing radiations.

THE EFFECT OF X-RADIATION ON THE GLUTATHIONE METABOLISM OF INTACT ERYTHROCYTES IN VITRO

The x-irradiation of intact washed erythrocytes results in an inhibition of the glyoxalase activity of the cells chiefly as a result of a decrease in the reduced glutathione level. The percentage inhibition is markedly increased by an increase in the dilution of the cells in physiological saline suggesting that the effect of radiation is indirect, via the production in the aqueous medium of free radicals, H(2)O(2), etc. This is supported by the decrease in the inhibition produced by lowering the oxygen tension or by the addition of catalase. The inhibition of glyoxalase activity is also decreased by the addition of methylglyoxal, plasma, adenosine, inosine, glucose, and a number of other sugars to the erythrocyte suspension prior to radiation. Furthermore, some reactivation of the glyoxalase system results from the addition of plasma, glucose, adenosine, and inosine following radiation. These results are discussed in relation to the role of SH compounds, particularly glutathione, in the toxicity of ionizing radiations.