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Rats were sacrificed at different times after injection of 14C-orotate and liver nuclei were isolated and incubated in a cell-free system made of soluble cytoplasmic fraction from non-irradiated rat livers. The release of ribonucleoproteins from labelled nuclei to the incubation medium was measured on nuclei from normal and total-body irradiated rats (500 to 2000 R). When using short labelling times in vivo (30 min), which would label predominantly messenger-type RNP, the nuclear transport activity was depressed at early times (3 h) after whole-body irradiation, but increased at later times (24 h). When the labelling time in vivo is increased to 2 h, no significant difference was observed between control and irradiated groups. Transport of the stable ribosomal-type RNP, observed 24 h after both labelling and irradiation, was depressed. These results are discussed in view of previous personal studies on radiation effect on liver RNA synthesis and polyribosomes formation in vivo.

Blood plasma lipids of women about seventy years old who had suffered from cardiovascular diseases (AVC) were studied and compared with the plasma lipids of women of about the same age without cardiac troubles. A great difference appears in the unesterified fatty acids of the phospholipids from cardiac women: we have observed a decreasing level of polyunsaturated fatty acids with a carbon chain of more than 18 carbons, and a decreasing ratio between the total concentration of the two precursors (linoleic acid omega and alpha-linolenic acid omega 3) and the total concentration of their long chain polyunsaturated derived fatty acids. On the contrary, we did not observe any significant variation of the unesterified fatty acid level in the plasma. The triglyceride and cholesterol levels also were not different between the two groups of patients. The hypothesis of a lack of elongation and of desaturation of linoleic and alpha-linolenic acids by competitive inhibition with oleic acid seems improbable, since the plasmatic concentration of oleic acid was not statistically different.

Pentane measurement in exhaled gases was proposed as a safe method to evaluate the importance of lipoperoxidation in vivo, in man and in animals. However we have observed that pentane, which arises from lipoperoxide decomposition, is significantly consumed by cytochrome P-450-rich liver microsomes. This pentane consumption is completely inhibited after heating the microsomes at 100 degrees C, and is considerably reduced by metyrapone, a cytochrome P-450 inhibitor. Hepatic metabolism of pentane, particularly after cytochrome P-450 induction, constitutes a risk of error, when pentane exhalation is taken as an index of lipoperoxidation in vivo.