Lipoxygenase and other enzymes of arachidonic acid metabolism in the brain of chicks affected by nutritional encephalomalacia.

1. Prostaglandin endoperoxide synthetase (PES) and lipoxygenase (Lox) activities were compared in the cerebella and cerebra of vitamin E-sufficient young chicks and in chicks in which nutritional encephalomalacia (NE) was induced by a diet deficient in vitamin E. 2. Eicosanoid production patterns were qualitatively similar in the brains of both groups of chicks, but prostaglandin production was 50-60% less in cerebella of ataxic chicks, compared to control cerebella, while the opposite trend was observed in the cerebellar Lox pathway, as measured by radioimmunoassay of 15-HETE. 3. Cerebellar phospholipase A2 activity was twice that of the cerebrum but was not affected by NE. 4. Purification of Lox activity from the cerebellar homogenates produced a lower yield and enrichment when the starting material was taken from ataxic chicks, compared to the controls. 5. In addition there were qualitative differences in the purified fractions from both groups, as seen by pH optima and kinetics. 6. The results are consistent with the view that the cerebellum has less antioxidant protection than the cerebrum and that its higher phospholipase A2 activity and greater propensity to oxygenate arachidonic acid via the Lox pathway at the expense of the PES pathway may render this region of the brain particularly vulnerable to oxidative damage in NE.

Lipoxygenase activity in the brain regions of young chicks: isolation and some properties.

1. The lipoxygenase (LOX) oxygenation pathway of arachidonic acid was investigated in the cerebellum and cerebral hemispheres of young chicks. 2. Lipoxygenase products consisted mainly of 15-hydroxyeicosatetraenoic acid (15-HETE), accompanied by the 15-hydroperoxy analog (15-HPETE) and the 5-HETE product. 3. The yield of 15-HETE was 3 times greater in the cerebellar system than in the cerebrum. 4. PLA2 activity of the cerebellum was twice that of the cerebrum. 5. Affinity chromatography revealed 2 brain fractions with LOX activity which were assayed with either linoleic or arachidonic acid as substrate. 6. The fraction eluted with 0.2 M sodium acetate pH 5.0, produced a higher yield and enrichment of LOX activity than the eluate obtained with 0.1 M Tris-HCl buffer (pH 8.0). 7. A considerably higher yield and enrichment of the enzyme was achieved when the starting material was the cerebellum, compared to the cerebrum. 8. The optimal pH for both purified fractions from cerebrum and cerebellum was 6.5, with either linoleic or arachidonic acid as substrate. 9. The cerebral LOX yielded Michaelis-Menten kinetics when linoleic acid was the substrate, while the corresponding plots for the cerebellar enzyme were sigmoidal. 10. Arachidonic acid as substrate produced sigmoidal plots, except at pH 5.0, where Michaelis-Menten kinetics were observed. 11. These results and the elevated activities of PLA2 and 15-LOX could be significant in relation to the special vulnerability of the cerebellum in chick nutritional encephalomalacia.

A study of blood total protein and albumin levels in psychiatric patients.

Statistical analyses showed that blood levels of albumin and total protein in psychiatric patients (N = 97) were significantly lower than those for the nonpsychiatric controls used to standardize the test values (N = 2,793). Levels did not differ as a function of discharge diagnosis. Thus, low blood total protein and albumin levels seem characteristic of the overall psychiatric inpatient population.

Reactive hypoglycemia and A-cell ('pancreatic') glucagon deficiency in the adult.

Serum glucose, A-cell (IRGA) and total glucagon (IRGT), insulin, growth hormone, cortisol, triiodothyronine, and thyroxine values were measured in the fasting state and in response to oral glucose, intravenously administered arginine, and a meal of pan-broiled ground beef in 31 symptomatic patients and 11 normal subjects. Twenty-four patients and 11 control subjects had normal glucose tolerance (group 1); seven patients had reactive hypoglycemia (group 2). Under all conditions, serum IRGA value was significantly lower in group 2 than in group 1. Glucose, arginine, or meat increased serum IRGT levels. This response did not differ significantly in the two groups, nor did the secretion of the other measured hormones. We conclude that A-cell insufficiency can contribute to reactive hypoglycemia in the adult.