[Influence of fasting and the dietary lipid content on ketogenesis in isolated rabbit hepatocytes]. / Influence du jeûne et de la teneur en lipides du régime sur la cétogenèse dans les hépatocytes isolés de lapin.

Ketogenesis was measured in isolated liver cells from fed or 48 h starved rabbits given either a low fat diet (3%) or a high fat diet (18%). In the fed rabbits, ketogenesis with butyrate, octanoate and oleate was greatly enhanced by the high fat diet. In the starved animals the increase in ketogenesis was moderate and only observed with oleate and butyrate. Results are discussed in relation to in vivo observations.

[Hyperoctanoatemia and the hepatic encephalopathy of cirrhosis. 150 dosages in 61 patients (author's transl)]. / Hyperoctanoatémie de l'encéphalopathie hépatique des cirrhoses. 150 dosages chez 61 malades.

A new and sensitive method for determination of octanoate in serum by gas-liquid chromatography is described. It was validated by mass spectrometry. Octanoate concentrations were determined in the serum of 61 fasting cirrhotic patients of which 47 also had hepatic encephalopathy. Concentrations in arterial and venous blood were higher in cirrhotic patients with encephalopathy than in those without and higher in the latter than in controls. Arterial concentrations were higher than venous concentrations and octanoate and ammonia varied independently. A predominant endogenous origin is likely. Data obtained from studies using palmitic acid labeled at different loci suggest that recovered serum octanoate was formed mostly by incomplete oxidation of long chain fatty acids. Sodium octanoate infusion to rhesus monkeys studied polygraphically induces a temporary coma.

Fatty acids. II. The synthesis and gas-liquid chromatographic behaviour of five trimethylene-interrupted C18-diunsaturated fatty acids.

Five trimethylene-interrupted methyl octadecadiynoates, C18 delta-2a,-7a; delta-3a,-8a; delta-4a,-9a; delta-5a,-10a and delta-6a,-11a, and the corresponding cis,cis-octadecadienoates were synthesized, and their gas-liquid chromatographic properties were studied on Apiezon L, diethylene glycol succinate polyester and Silac 10C stationary phases. The equivalent chain lengths of these esters have been determined, and the separation of mixtures and the prediction of gas chromatographic behaviour of these isomers are discussed.

Genetic regulation of octane dissimilation plasmid in Pseudomonas.

The enzymes responsible for the oxidation of n-octane to octanoic acid or beyond in Pseudomonas oleovorans are octane inducible and are coded by genes borne on a transmissible extrachromosomal element. The octane to octanoate enzymes induced by octane are repressed by octanol. The chromosome also carries genes coding octanol oxidation enzymes that, in contrast, are induced by octanol, not by octane. The octane plasmid has been transferred from P. oleovorans to several other fluorescent Pseudomonas species. In exconjugants, the presence of both octane and camphor plasmids enhances their segregation rate.

Fatty acid biosynthesis in rabbit mammary gland during pregnancy and early lactation.

The pattern of fatty acids synthesized by mammary-gland explants from rabbits during pregnancy and early lactation has been studied. From day 12 to day 18 of pregnancy, long-chain (C(14:0)-C(18:1)) fatty acids were the major products. From day 18 to day 21 of pregnancy there was an increase of up to 12-fold in the rate of fatty acid synthesis per unit wet weight of tissue that was almost exclusively caused by the synthesis of octanoic fatty acid and decanoic fatty acid, which are characteristic of rabbit milk. These medium-chain fatty acids were mainly incorporated into triglycerides. From day 22 to day 27 of pregnancy there was little change in the rate of fatty acid synthesis and the proportions of fatty acids synthesized were essentially the same as those synthesized by the lactating gland, i.e. 80-90% octanoic acid plus decanoic acid. About 2-4 days before parturition a second lipogenic stimulus occurred, although the pattern of fatty acids synthesized did not change.