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Biomedical subjects

G Durand

Publications and source records attributed to G Durand.

At least 235 records · Page 13Linked to original sources
PubMed1987

Slow recovery of the fatty acid composition of sciatic nerve in rats fed a diet initially low in n-3 fatty acids.

The sciatic nerve of rats fed sunflower oil (6 mg 18:3-n-3/100 g of diet) presented dramatic alterations in the long chain polyunsaturated fatty acids in comparison with those fed soy oil (130 mg 18:3n-3/100 g of diet). In both 15-day-old and 60-day-old animals fed sunflower oil, 22:6n-3 (cervonic acid) was four-fold less, 22:5n-6 was 10-fold greater; adrenic acid (22:4n-6) was slightly greater and arachidonic acid (20:4n-6) was close to that in rats fed soy oil. The percentage distribution of total polyunsaturated fatty acids as well as the individual saturated and monounsaturated fatty acids were the same in both groups. When the sunflower oil-fed animals were switched to a soy oil-containing diet for either 15 or 60 days, the percentage distribution of 22:6n-3 increased slowly to reach the control value 2.5 months later. Conversely 22:5n-6 decreased slowly. The decay of 22:5n-6 was more rapid than the increase of 22:6n-3.

Animals↗
PubMed1986

Effect of phenobarbital on the oligosaccharide structure of rat alpha-acid glycoprotein.

We have recently shown that the administration of phenobarbital to rats leads to an increased serum alpha 1-acid glycoprotein content with alterations in the relative proportion of the sugar moiety. Therefore, alpha 1-acid glycoprotein was purified from normal (alpha 1-acid glycoproteine N) and phenobarbital-treated rats (alpha 1-acid glycoprotein PB) Glycans were separated by AX-10 chromatography and analysed by gas chromatography. It appears that, compared to alpha 1-acid glycoprotein N, alpha 1-acid glycoprotein PB had a higher carbohydrate content (31.7% compared to 26%) and a non-negligible amount of neutral oligosaccharide (12.2% compared to 1.3%). No tetrasialyl oligosaccharides in alpha 1-acid glycoprotein PB were detected, whereas their relative proportion in alpha 1-acid glycoprotein N was 27%.

Animals↗
PubMed1986

In vivo quantification of removal of asialo-orosomucoid from the circulation in anaesthetized streptozotocin-diabetic rats.

The in vivo kinetic of removal of 3H asialo-orosomucoid from plasma was investigated in control and streptozotocin-diabetic rats after intravenous injection of 1 mg of asialo-orosomucoid/100 g body wt. Michaelis-Menten kinetics of disappearance were observed. In diabetic rats the maximal rate (Vmax) of disappearance of 3H asialo-orosomucoid was decreased by 30% with no modification of Michaelis constant. Since no accumulation of desialylated orosomucoid in the circulation was observed, the slower rate of removal of 3H asialo-orosomucoid was attributed to a decrease in the number of hepatic asialoglycoprotein receptors which are largely involved in the catabolism of asialoglycoproteins. Our estimate on in vivo maximal rates was 10- to 20-fold greater than our previous in vitro estimate of the maximal rate of endocytosis. In contrast, the values of the Michaelis constant obtained in vivo and in vitro were very similar.

Animals↗
PubMed1986

Alterations in relative proportions of microheterogenous forms of human alpha 1-acid glycoprotein in liver disease.

To determine whether liver damage correlates with typical changes in alpha 1-acid glycoprotein (alpha 1-AGP) carbohydrate branching, we selected patients with liver disease determined by histological liver findings. The severity of their illness was assessed by a clinical classification depending on the presence singly or together of four clinical complications (jaundice, ascites, hepatic encephalopathy and weight loss). An alpha 1-AGP crossed immunoelectrophoresis with Concanavalin A, an easy-to-perform method, revealed 3 or 4 subpopulations, the areas of which were calculated. A ratio R was determined as the most anodic peak area relative to the other ones. In our experimental conditions a ratio R value exceeding 1 correlated with the presence of one or more clinical complications. These results, evidencing fluctuations in the proportion of the carbohydrate variants of alpha 1-AGP, lead us to propose such a ratio as an index for grading liver damage. The sensitivity of this test was 86% and its specificity was 83%.

Clinical Laboratory Techniques↗
PubMed1986

Dietary alpha-linolenic acid deficiency in the rat. I. Effects on reproduction and postnatal growth.

The effects of a dietary alpha-linolenic acid (18 : 3 n-3) deficiency on reproduction and postnatal growth in rats were studied during 3 successive gestations and 4 successive generations. Female rats received respectively a semi-synthetic diet in which the lipids were incorporated either as sunflower oil at 1.5% (deficient diet) or as soya oil at 1.87% (control diet). Both diets supplied the same amount of linoleic acid (18 : 2 n-6) (940 mg/100 g of diet), but the sunflower oil supplied 22 times less alpha-linolenic acid than the soya diet (6 mg vs 130 mg/100 g of diet). The results showed that, in our experimental conditions, the alpha-linolenic acid deficiency had no effect on fecundity (% of pregnant females), fertility (number of pups/litter), pup birth weight, food intake and weight of pregnant or lactating females, or pup growth during suckling. However, this deficiency did cause abnormally high rates of perinatal mortality from birth to postpartum day 3, namely on the average, for successive gestations: 18.5% in deficient pups vs 5.2% in the controls, and for successive generations: 16.6% in deficient pups vs 5.3% in the controls. Rat n-3 PUFA requirement during reproduction has been discussed; it appears to be more than 100 mg/100 g of feed. But this need should also be estimated in relation to n-6 PUFA supply; for female rats during reproduction, the ratio n-6: n-3 should be less than 10.

Aging↗
PubMed1986

Recovery of altered fatty acid composition induced by a diet devoid of n-3 fatty acids in myelin, synaptosomes, mitochondria, and microsomes of developing rat brain.

Rats were fed a semisynthetic diet containing either sunflower oil or soya oil. Half the litter fed with sunflower oil diet was changed to a soya oil diet when the pups were 15 days old (during active myelination). Fatty acid analysis was then performed on subcellular fractions of the animals fed (a) soya oil, (b) sunflower oil, and (c) soya oil replacing sunflower oil from the 15th day, to determine the speed of the recovery. All material from animals fed sunflower oil showed an important reduction in docosahexaenoic acid (22:6 n-3), compensated by an increase in docosapentaenoic acid (22:5 n-6), whereas arachidonic acid (20:4 n-6) was not affected. In all fractions examined, when sunflower oil was replaced by soya oil in 15-day-old pups the recovery started from the very first day but lasted more than 2 months (this recovery was determined by the increase of 22:6 n-3 up to the normal value and decrease of the 22:5 n-6). In addition a delay was found for myelin recovery, starting only from the 25th day.

Animals↗
PubMed1986

Inhibitory effect of sodium arsenite and azide on asialoglycoprotein receptor mediated endocytosis in suspended rat hepatocytes.

The inhibitory effect of sodium arsenite and azide on asialoorosomucoid endocytosis was tested using isolated rat hepatocytes. Under either continuous flux conditions or a single synchronous wave of ligand endocytosis we confirm that azide inhibits the recycling of the receptors and we provide evidence for the involvement of thiol groups in the internalization step. In addition pretreatment of hepatocytes with azide allows us to demonstrate that receptor endocytosis proceeds independently of the presence of any specific ligand.

Animals↗
PubMed1986

[Gluconeogenesis, ketogenesis, and ureogenesis in isolated hepatocytes from diabetic rats: effects of insulin].

The intermediary metabolism in hepatocytes isolated from diabetic rats has been studied. The incubation medium is a Krebs-Henseleit buffer containing albumin-bound oleate (1 mmol/l). The high rates of gluconeogenesis, ureogenesis and ketogenesis were consistent with the diabetic state of the rats. Insulin (8 X 10(-7) mol/l) decreased glucose and urea productions from alanine (10 mmol/l) by 30%; beta-hydroxybutyrate production, oleate utilization and malate efflux (calculated) from mitochondria were also decreased. No effect of insulin was found with lactate (10 mmol/l) as gluconeogenic substrate. The glycogen content of cells was constant during the time of incubation (4h). These data suggest that the oxidation-reduction state of mitochondria and the cytoplasmic oxaloacetate concentration could be important factors in the action of insulin.

Alanine↗
PubMed1985

Kinetic evidence of a surface membraneous step during the endocytosic process of 3H-labelled asialoorosomucoid and its alteration in diabetic mellitus rats.

The apparent internalization rate constant of asialoorosomucoid in normal and diabetic hepatocytes was determined using different experimental processes, either following a synchronous wave of prebound ligand or a continuous flux ligand endocytosis, either alone or simultaneously. In continuous flux conditions, no difference between normal and diabetic hepatocytes appeared (k = 0.15 +/- 0.04 and 0.11 +/- 0.02 min-1, respectively). In contrast, in the one-turn endocytosis of prebound ligand, k was lower for diabetic hepatocytes than for normal ones whether it was measured alone (0.20 +/- 0.03 and 0.59 +/- 0.09 min-1, respectively) or simultaneously with a continuous flux of unlabelled ligand (0.25 +/- 0.03 and 0.70 +/- 0.08 min-1, respectively). These differences are attributed to an impediment or a delay in the preclustering of receptors in coated pits at the cell surface of diabetic cells.

Animals↗
PubMed1985

Study of hepatic binding protein activity in jejuno-ileal by-passed rat hepatocytes.

The kinetic constants of internalization of asialoorosomucoid were determined for normal and jejuno-ileal by-passed rat hepatocytes. In by-passed rats the maximum velocity of asialoorosomucoid internalization is decreased 3-fold, without any modification of apparant constant of internalization. Moreover, the rate constant of internalization was the same in the two groups of rats. These data suggest that the process of asialoorosomucoid internalization is not altered in by-passed hepatocytes and that the decrease of maximal velocity is only due to a decrease of total uptake receptor number.

Animals↗
PubMed1985

Comparative changes in the lipogenic enzyme activities and in the in vivo fatty acid synthesis in liver and adipose tissues during the post-weaning growth of male rats.

Changes in the specific activities of acetyl-CoA-carboxylase (ACX), malic enzyme (ME) and glucose-6-phosphate dehydrogenase (G-6-PD) were compared to changes in de novo lipogenesis measured by in vivo incorporation of [3H] of tritiated water into fatty acids of liver and of perirenal and dorsal subcutaneous adipose tissues. In the adipose tissues, the specific activities of the three enzymes rather closely followed fluctuations in the rate of fatty acid synthesis. In the liver, ACX and especially ME activities were satisfactory indicators of de novo lipogenesis; G-6-PD activity did not depend on de novo lipogenesis.

Acetyl-CoA Carboxylase↗
PubMed1985

[Fructose utilization by hepatocytes isolated from fed obese fa/fa Zucker rats. Metabolic fate of fructose in the absence of the modulator].

The utilization of fructose by isolated hepatocytes was investigated in fed obese Zucker fa/fa rats compared with their lean littermates (Fa/?) and Sprague-Dawley rats. Hepatocytes were incubated during 3 h using U14C fructose (20 mM). Our results show: a significant increase of fructose consumption, glucose, lactate and pyruvate production and faster turnover of glycogen by fa/fa rats. In these animals, synthesis of acylglycerol was also significantly enhanced. Our results suggest that fructose in fa/fa rats was used preferentially as precursor for lipid synthesis not only by the liver but also by the adipose tissue after a prior transformation into glucose by hepatocytes. All these abnormalities result in an accumulation of acylglycerols maintaining an obesity state in fa/fa rats.

Animals↗
PubMed1985

D-galactosamine-induced liver injury: a rat model to study the heterogeneity of the oligosaccharide chains of alpha 1-acid glycoprotein.

The effect of D-galactosamine on the structure of the glycan moiety of alpha 1-acid glycoprotein was studied throughout a nine days experiment. It was shown that: D-galactosamine led to an alteration of the Concanavalin A crossed immunoelectrophoresis pattern and to a decreased sialic acid content of alpha 1-acid glycoprotein. The undersialylation of alpha 1-acid glycoprotein was not linked to a change in the relative ratio of various Concanavalin A forms. At the end of the experiment (9 days after galactosamine injection), the Concanavalin A non-reactive forms of alpha 1-acid glycoprotein remained elevated whereas alanine transaminase activity, total protein and alpha-acid glycoprotein had returned to a control level. D-galactosamine-treated rats seem to be a suitable model for the study of the very fast cyclic modulations of the synthesis of the glycan moiety of glycoproteins.

Animals↗
PubMed1985

[Adipose tissue cellularity in the piglet as a function of the level of energy supply of the maternal diet and the number of young per litter].

Adipose tissue cellularity has been evaluated in piglets at birth and at weaning at 35 days in relation with the energy supply of the maternal diet during gestation (group B: 3 000 KcalED/day: group N; 6 500 KcalED/day; group H: 10 000 Kcal/day) and with the number of piglets per litter during suckling. This approximation was obtained by simultaneously measuring piglet carcass triglyceride content and the mean diameter of the lipid inclusions of the fat cell population. At birth there were no significant differences between N and H piglets. However, B piglets weighed less and had lower lipid stores than the piglets of the other two groups. This lower adiposity was due to the smaller number of fat cells (about--25%). A weaning piglet weight and adiposity depended on both the energy supply of the maternal diet during gestation and the number of piglets per litter. These differences were due to the number of fat cells; this number was usually greater when the maternal diet during gestation had a higher energy level and the number of piglets per litter was smaller. Between birth and weaning the number of fat cells increased by a factor related with the number of piglets per litter; this factor was 1.9 or 2.5, depending on whether the sow suckled 4 or 8 piglets.

Adipose Tissue↗
PubMed1985

[Specific contribution of dietary polyunsaturated fatty acids of the n-3 series to the development of nervous system membranes].

Polyunsaturated fatty acids, especially omega 3 fatty acids, made a specific contribution to the nervous tissue. Retarded intrauterine growth caused a twofold reduction in the oligodendrocyte ratio of omega 3/omega 6 while the same ratio increased by more than twofold in the neurons. A fatty acid-poor diet composed of arachid or sunflower oil dramatically altered the composition of cells and subcellular particles when compared with a soya or rapeseed oil diet containing omega 3 fatty acids; phosphatidylethanolamine was particularly affected. Nerve cell culture showed that brain essential fatty acids are probably docosahexaenoic acid and arachidonic acid.

Animals↗