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D Petit

Publications and source records attributed to D Petit.

At least 73 records · Page 4Linked to original sources
PubMed1982

Lack of induction of VLDL apoprotein synthesis by medium chain fatty acids in the isolated rat liver.

Long chain fatty acids (greater than C16) are known to induce the liver synthesis of very low density lipoprotein (VLDL) apoproteins. Since medium chain (less than C16) triglycerides are used as dietary fats and in parenteral nutrition, we have investigated the relative uptake, esterification and oxidation of 14C-labelled fatty acids of a chain length of C10-C14 by the perfused rat liver compared to palmitic acid at two different concentrations: tracer (control) and overload (200 or 600 mumol/200 ml perfusate). The effect on VLDL apoprotein synthesis was simultaneously estimated by 3H-leucine incorporation. The results show: (1) a rapid liver uptake of all fatty acids; (2) a substantial incorporation into liver lipids of C12-C14 and C16, and (3) a higher oxidation rate of medium chain compared to long chain fatty acids; a lack of induction of VLDL apolipoprotein by an overload of fatty acids shorter than palmitic acid in spite of their utilisation for liver and VLDL lipid synthesis. Possible explanations for these differences are discussed.

Animals↗
PubMed1976

Effects of glycerol on VLDL secretion by the isolated rat liver.

Stimulation of VLDL production by increasing fatty acid availability is now well established. However, a possible regulatory role of glycerol, another lipid precursor, in VLDL synthesis by the liver has not yet been substaniated. The present experiments investigate this problem using the isolated perfused rat liver. [14C] Glycerol uptake and metabolism were studied at two different glycerol concentrations: 1 mumol/perfusate (control) or 1.6 mmol/perfusate. VLDL production and lipid synthesis were investigated using [14C]leucine and several labelled fatty acids as precursors in control and glycerol-overloaded livers. Neoglycogenesis and lipogenesis from glycerol carbons are negligible in our conditions. The absolute amount of glycerol, but not the precentage, taken up by the liver, increased after raising its concentration in the perfusate. A major part of exogenous (plasmatic) glycerol was esterified with endogenous (non plasmatic) fatty acids. Incorporation of radioactive fatty acids into liver or plasma lipids was lower than in the the control group. Significant differences were observed between saturated and unsaturated fatty acids used as lipid precursors. Production of VLDL as assessed by radioactive leucine and fatty acid incorporation in the VLDL of the perfusate was depressed by glycerol. Glycerol partly inhibits the normal stimulation of VLDL production by plasmatic fatty acid overload.

Animals↗
PubMed1970

Place and modality analysis in nucleus of posterior commissure.

1. Single units (157) responsive to somatic stimulation in the nucleus of the posterior commissure were examined in the cat under chloralose anaesthesia. 87.3% responded to stimulation of all four limbs, 2.4% to three limbs, 8.7% to two limbs and 2% to one limb.2. 44.7% of units could be activated by phasic hair movement; 52.4% responded additionally to auditory stimuli and 34.6% to visual stimuli, although there are marked differences in degree of heterosensory convergence between hair-sensitive units and others.3. Analysis by spike numbers and latencies show marked preference for contralateral limbs.4. Results are compared with those obtained under identical experimental conditions from units of the gigantocellular bulbar reticular formation, and show that anatomically discrete areas of the reticular formation are capable of differential analysis of afferent input.

Animals↗