In a previous investigation carried out in this Laboratory (Beloff-Chain et al. 1953) it was found that isolated rat diaphragm synthesized glycogen from glucose and from glucose 1 -phosphate to about the same extent when the substrate concentration, calculated as glucose, was 2 %. There was little or no glycogen synthesis from glucose 6-phosphate at this concentration. Further, it was shown that insulin had no stimulatory effect on glycogen synthesis from glucose 1-phosphate as it had from glucose.

1) The metabolism of two l4C-labe1led hexoses and one hexose analogue, viz. mannose, fructose and glucosamine, has been compared with that of glucose for slices of rat cerebral cortex incubated in vitro.(2) The metabolism of [U-14C]mannose was essentially identical to that of glucose; oxygen consumption and COB production were similar and maximal at a substrate concentration of 2.75 mM. Incorporation of label into lactate, aspartate, glutamate and GABA was similar for the two substrates at 5.5 m~ substrate concentration.(3) With [U-14Clfructose, maximal oxygen consumption and C 0 2 production were obtained at a substrate concentration of 11 m. At 5.5 mM, incorporation into lactate was 5 per cent, into glutamate and GABA 30 per cent, into alanine 63 per cent and into aspartate 93

New Zealand male rabbits, on a moderate dietary fat intake (10.2% w/w) received, as the major dietary lipid, butter, olive oil and corn oil, respectively, for a period of 8 weeks. At the end of the dietary treatment, plasma total cholesterol was significantly decreased in the corn oil group, compared to butter, whereas the olive oil-consuming rabbits had an intermediate cholesterolemia; the corn oil and olive oil groups had significantly elevated high-density lipoprotein (HDL) cholesterolemia, compared to the butter group. Maximal platelet aggregability, with collagen and arachidonic acid, did not appear to differ in the three treatment groups. Thromboxane B₂ release in the sera of treated rabbits was slightly higher after corn oil administration. The arterial release of prostacyclin (PGI₂), tested by perfusing platelet-rich plasma through the aorta of donor rabbits, was lowest in the corn oil group. Corn oil is the most effective dietary fat in reducing cholesterolemia, but it may also reduce PGI₂ release from arteries. Butter has the most unfavorable effect on lipidemia and HDL-cholesterol, whereas dietary olive oil shows an intermediate lipid-lowering activity but preserves arterial PGI₂ production.

A semisynthetic diet containing adequate amounts of vitamin E and 10% (w/w) of a mixture of polyunsaturated oils subjected to heating and characterized by elevated indexes of thermal alteration (polar component, dimer triglyceride, altered triglyceride contents and reduced alpha-tocopherol levels) was fed to growing male rats for a period of eight weeks. It resulted in a selective alteration of the production of vascular eicosanoids (elevation of platelet thromboxane formation and decrease of vascular prostacyclin release) compared to the values found in rats fed a diet containing a fresh mixture of polyunsaturated oils. Major nutritional parameters, plasma lipids and the fatty acid profiles of plasma, liver and heart lipids were not different in the two groups of animals. Supplementation of an excess vitamin E (300 mg/kg) to the diet containing heated fat neutralized the adverse effects of heated fat on vascular eicosanoid production.

The fate of uniformly labelled 14 C glucose in rat-brain slices has been followed by a quantitative application of the radio paper-chromatography technique. After 60 min incubation with brain tissue approximately 60% of the glucose disappearing from the medium was accounted for as lactic acid, about 20% as CO 2 and most of the remainder as free amino-acids. Of the total glucose metabolized approximately 9% was converted into glutamic acid, 1.5% alanine, 3% γ -amino-butyric acid and 2.4% aspartic acid. Glutamic acid was the first of the amino-acids to be formed from glucose, and was detectable after 3 min incubation of brain tissue with 14 C glucose. Insulin had no effect on glucose metabolism in brain slices. Under anaerobic conditions the total glucose metabolized by brain slices was only about 10% of that found under aerobic conditions; of the total glucose disappearing from the medium anaerobically about 80% was accounted for as lactic acid and the remainder as free unchanged glucose in the tissue cells.