Further studies of dopamine metabolism and function in Tetrahymena

The large amounts of dopamine accumulated by cells of Tetrahymena pyriformis strain NT-1 and secreted into their growth medium were found to depend primarily upon an extracellular, non-enzymatic conversion of tyrosine to L-dihydroxyphenylalanine (L-DOPA); L-DOPA was then rapidly taken into the cells and transformed into dopamine enzymatically. Efforts to find physiologically significant dopamine binding sites on the cell surface or dopamine-sensitive adenylate cyclase activity were unsuccessful, suggesting that the catecholamine does not function in Tetrahymena as it does in higher animals.     

Further studies of sulphasalazine metabolism in the treatment of ulcerative colitis.

Sixty-four outpatients with ulcerative colitis receiving maintenance treatment with sulphasalazine were studied to relate disease activity to serum concentrations of sulphapyridine. Of 43 patients in remission, 32 had serum sulphapyridine levels over 20 microgram/ml. Ten of the 21 patients with active disease were for various reasons taking inadequate doses of sulphasalazine, as indicated by low serum sulphapyridine levels, and of the remaining 11 patients, who had serum levels over 20 microgram/ml, nine had faecal stasis proximal to active distal colitis and went into remission when treated with hydrophilic colloid or bran and an unchanged sulphasalazine dosage. This suggests that to be effective the metabolites of sulphasalazine must be delivered in the faeces to the lumen of the diseased distal segment of the colon. High serum concentrations of sulphapyridine produce side effects; therefore slow acetylators of sulphapyridine need lower doses of sulphasalazine. Estimations of serum sulphapyridine concentrations, as well as identifying the patient''s acetylation phenotype, can also be useful in assessing his compliance with treatment.     

Further studies on the regulation of amino sugar metabolism in Bacillus subtilis

1. Glucosamine 6-phosphate deaminase [2-amino-2-deoxy-d-glucose 6-phosphate ketol-isomerase (deaminating), EC 5.3.1.10] of Bacillus subtilis has been partially purified. Its K_m is 3·0mm. 2. Extracts of B. subtilis contain N-acetylglucosamine 6-phosphate deacetylase (K_m 1·4mm), glucosamine 1-phosphate acetylase and amino sugar kinases (EC 2.7.1.8 and 2.7.1.9). 3. Glucosamine 6-phosphate synthetase (l-glutamine–d-fructose 6-phosphate aminotransferase, EC 2.6.1.16) is repressed by growth of B. subtilis in the presence of glucosamine, N-acetylglucosamine, N-propionylglucosamine or N-formylglucosamine. Glucosamine 6-phosphate deaminase and N-acetylglucosamine 6-phosphate deacetylase are induced by N-acetylglucosamine. Amino sugar kinases are induced by glucose, glucosamine and N-acetylglucosamine. The synthesis of glucosamine 1-phosphate acetylase is unaffected by amino sugars. 4. Glucose in the growth medium prevents the induction of glucosamine 6-phosphate deaminase and of N-acetylglucosamine 6-phosphate deacetylase caused by N-acetylglucosamine; glucose also alleviates the repression of glucosamine 6-phosphate synthetase caused by amino sugars. 5. Glucosamine 6-phosphate deaminase increases in bacteria incubated beyond the exponential phase of growth. This increase is prevented by glucose.     

Further studies on the effects of dehydroepiandrosterone on hepatic metabolism in BHE rats

Two experiments were conducted to determine the effects of dehydroepiandrosterone (DHEA) on de novo fatty acid synthesis and oxygen consumption in BHE rats fed a 65% glucose diet. In Experiment 1, starved glucose-refed rats were injected ip with 120 mg of DHEA/kg body wt and hepatic de novo fatty acid synthesis was measured. DHEA-treated rats synthesized less fatty acid in response to starvation refeeding than nontreated rats. In Experiment 2, weanling rats were fed the glucose diet for 4 weeks. One-hundred twenty milligrams of DHEA/kg were injected daily for 3 weeks. Body weight gain, epididymal fat pad weight, and carcass lipid were less in the DHEA-treated rats than in the control rats. Mitochondrial respiration was less and liver size was greater in DHEA-treated rats compared with control rats. Whole body oxygen consumption was increased in DHEA-treated rats, suggesting that this steroid might be stimulating futile energy cycles involving lipid and protein turnover possibly through its effect on glucocorticoid and thyroid hormone function.     

Further studies on the carbohydrate metabolism of immature Schistosoma mansoni

Further studies on the carbohydrate metabolism of immature Schistosoma mansoni. International Journal for Parasitology 3: 783–787. Analysis of whole cercariae, cercarial bodies and tails and schistosomula shows the tail contains 26 per cent of the cercarial nitrogen, 46 per cent of the glycogen and 59 per cent of the cytochrome oxidase. 32 per cent of the total nitrogen and 22 per cent of the glycogen of the cercarial body is lost during penetration. Oxygen uptake of adult worms but not of cercariae increases between 30 and 37°C. A temperature of 41°C partly inhibits cercarial oxygen uptake but not that of adult worms. Incubation of schistosomula, 21-day-old and adult worms in nitrogen increases the rate of glycolysis.     

Further studies of the effects of an anovulatory drug on lipid metabolism in the rat

The effect of various levels of the oral contraceptive drug, Enovid E, on serum and liver lipid levels of adult female rats has been investigated. Doses ranging from 0.052 to 1.04 mg/day have been employed in rats fed control or cholesterol-containing diets. It has been confirmed that after administration of even low, physiological doses of the drug, esterified cholesterol in serum and adrenals decreases rapidly while at the same time it accumulates in the liver; cholesteryl oleate is increased while the relative amount of cholesteryl arachidonate is reduced. Serum phospholipids also are decreased; the alpha/beta lipoprotein ratio is significantly reduced due to the decrease of alpha-lipoproteins. Most of these changes also occur in cholesterol-fed rats. The observed effects are not related to a decreased food intake.