The current low consumption of n-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) led scientists to wonder about the possible enrichment of human food, including meats such as beef, with n-3 LCPUFA. However, their biosynthesis from dietary n-3 PUFA seems limited in mammalian tissues implying that a better understanding of the molecular mechanisms responsible for this down regulation is needed. This study aimed at identifying and comparing the limiting steps of n-3 LCPUFA synthesis in liver, intermuscular adipose tissue (IM-AT) and semitendinosus muscle (ST) from six Limousin bulls. Tissue FA composition was analysed by GLC and mRNA abundance of enzymes and transcription factors involved in n-3 LCPUFA synthesis was assessed by RT-qPCR. In liver, mRNA encoding proteins involved in n-3 LCPUFA synthesis were present in agreement with the significant high content of n-3 LCPUFA (8.4 mol% of total FA, 257 mg/100 g of fresh tissue) in this organ. In IM-AT, these mRNA were all present, but at a tenfold lower intensity than in liver in agreement with the low contents of n-3 LCPUFA in this tissue. In ST muscle, these mRNA were all present except elongase 5 mRNA which was only present as trace, the corresponding protein being undetectable, probably inducing a break of n-3 LCPUFA synthesis from 18:4n-3. In conclusion, Limousin bull ST muscle seemed unable to synthesize n-3 LCPUFA. However, the presence of 20:5n-3 (EPA) and 22:5n-3 (DPAn-3) in muscle raised the question of the origin of these n-3 LCPUFA.

The distinctive extra-virgin olive oil aroma consists of a complex mixture of volatile compounds. We comparatively studied the volatiles of eight autochthonous monovarietal extra-virgin olive oils from the north-east part of Algeria via headspace solid-phase microextraction GC-MS. We determined the effect of ripening of Chemlal olive fruit on aroma compounds. Twenty volatile analytes belonging to different chemical classes were identified and quantified. Both quantitative and qualitative differences were found among cultivars, indicating a close dependence of the composition of the volatile profile on the enzymatic pool, directly related to genetic characteristics. Moreover, differences in volatiles composition were observed for Chemlal oils during maturation.

N-3 long-chain (LC) PUFA are known to be beneficial for human development and health. These properties explain the increasing interest in promoting n-3 LC PUFA deposition in bovine muscles, leading to healthier meats. In this context, this study aimed to identify possible limiting steps in the bioconversion of 18:3n-3 into n-3 LC PUFA in the longissimus thoracis (LT) muscle of 36 Aberdeen Angus, Limousin, and Blond d'Aquitaine bulls (n = 12 per breed) that were fed, for the 105-d finishing period, either a concentrate-based diet (25% molasses straw to 75% concentrate, on a raw basis; CON) or the same CON diet supplemented with extruded linseed (44.5 g lipid/kg diet DM) mixed into the concentrate (LINS). The fatty acid (FA) composition of the LT muscle was determined by GLC, and the mRNA abundances for enzymes and transcription factors involved in n-3 LC PUFA synthesis were determined by quantitative real-time PCR. The total lipid concentration in the LT muscle was approximately 2.4-fold greater (P < 0.001) in Angus bulls than in the other breeds and composed of the greatest n-3 PUFA content (P < 0.001) including 18:3n-3 (P < 0.001) and n-3 LC PUFA (P < 0.02), primarily 20:5n-3 (P < 0.007) and 22:5n-3 (P < 0.04). These data were associated with a lesser gene expression (P < 0.02) of 2 enzymes [acyl-CoA oxidase 1 (ACOX1) and L-bifunctional protein (L-PBE)] and 2 transcription factors [liver X receptors (LXR) α and β] in the LT muscle of Angus bulls compared with gene expression in Limousin bulls. Moreover, the mRNA of elongase 5 was only present in trace amounts in the LT muscle of the 3 breeds. The addition of linseed to the diet resulted in greater deposition of 18:3n-3 (P < 0.001) in the LT muscles of the 3 breeds, without any major changes (P > 0.34) in the n-3 LC PUFA content. Dietary linseed stimulated (P < 0.04) the gene expression of all enzymes and transcription factors involved in n-3 LC PUFA synthesis except elongases 2 and 5 (P > 0.19), the expression of which remained weak and was not inducible. These results reveal a limited capacity for n-3 LC PUFA synthesis from 18:4n-3 (substrate of elongase 5) in the LT muscles of Blond d'Aquitaine, Limousin, and Angus bulls. Therefore, further investigations on the cellular regulation of elongase gene expression are needed to identify the physiological or nutritional factors that efficiently stimulate elongase expression in beef cattle.

The pharmacokinetics as well as erythrocyte and plasma protein binding of doxycycline were studied in fifteen patients with various renal function impairments after oral doxycycline polyphosphate single administration. Plasma half‐life (t 1/2), area under the plasma concentration‐time curve (AUC), urinary excretion, renal clearance, erythrocyte and plasma protein binding (%) were regressed vs creatinine clearance. No significant correlations were observed between t 1/2 or AUC and renal function nor plasma protein binding and plasma albumin concentrations. Significant correlations were obtained between urinary excretion, renal clearance, erythrocyte binding, plasma protein binding and creatinine clearance. Significant correlation was obtained between haematocrit and erythrocyte binding. Constancy of overall elimination parameters in renal failure is due to parallel increase in plasma free fraction of doxycycline.