Depletion of delta 9 desaturase (EC 1.14.99.5) activity in lactating rat during protein restriction.

The effects of protein restriction on the activity of delta9 desaturase (EC 1.14.99.5) were investigated in lactating rats. A control group was fed a balanced diet (20% casein) for 14 days, whereas the experimental groups were fed a low-protein diet (8% casein), supplemented with or without L-methionine (0.4%), for 14 days. The enzyme activity was measured by incubations of hepatic microsomal pellets with (1-14C) stearic acid. Results showed a decreased delta9 desaturase activity, after 2,7 and 14 days of depleted diet, of -50, -40 and -33% respectively, compared with control. The supplementation of the low-protein diet with 0.4% methionine, which favours food consumption as well as growth, did not improve the altered delta9 desaturase activity. Our data evidenced that delta9 desaturase activity is depleted by protein restriction during lactation, when the protein needs are high for the biosynthesis of animal tissues. This change has to be considered as a sign of depressed delta9 desaturase biosynthesis or modifications of enzymatic properties, or both.

Effect of chronic magnesium supplementation on magnesium distribution in healthy volunteers evaluated by 31P-NMRS and ion selective electrodes.

AIMS: The role of magnesium (Mg) intake in the prevention and treatment of diseases is greatly debated. Mg biodistribution after chronic Mg supplementation was investigated, using state-of-the-art technology to detect changes in free ionized Mg, both at extra- and intracellular levels. METHODS: Thirty young healthy male volunteers participated in a randomised, placebo (P)-controlled, double-blind trial. The treated group (MgS) took 12 mmol magnesium lactate daily for 1 month. Subjects underwent in vivo 31P-NMR spectroscopy and complete clinical and biological examinations, on the first and last day of the trial. Total Mg was measured in plasma, red blood cells and 24 h urine ([Mg]U ). Plasma ionized Mg was measured by ion-selective electrodes. Intracellular free Mg concentrations of skeletal muscle and brain tissues were determined noninvasively by in vivo 31P-NMR at 3T. NMR data were automatically processed with the dedicated software MAGAN. RESULTS: Only [Mg]U changed significantly after treatment (in mmol/24 h, for P, from 4.2+/-1.4 before to 4.1+/-1.3 after and, for MgS, from 3.9+/-1.1 before to 5. 1+/-1.1 after, t=2.15, P=0.04). The two groups did not differ, either before or after the trial, in any other parameter, whether clinical, biological or in relation with the Mg status. CONCLUSIONS: Chronic oral administration of Mg tablets to young healthy male volunteers at usual pharmaceutical doses does not alter Mg biodistribution. This study shows that an adequate and very complete noninvasive methodology is now available and compatible with the organization of clinical protocols which aim at a thorough evaluation of Mg biodistribution.

Inositol and choline levels in the diet and neutral lipid hepatic content of lactating rat.

During lactation a methionine supplemented low protein diet or a sufficient protein diet containing 40% of fructose induced an important hepatic lipidosis. Inositol supplementation, but not choline supplementation, strongly reduced, in the case of a low protein diet, and suppressed, in the case of a sufficient protein diet, this lipidosis.

Hypophosphatemia after cardiothoracic surgery.

The incidence of hypophosphatemia during the first 48 h following cardiothoracic surgery was prospectively studied in 74 patients. Hypophosphatemia, defined by a serum phosphate below 2.50 mg/dl, was observed in 19 of 34 (56%) patients after thoracic surgery and in 20 of 40 (50%) patients after cardiac surgery. As a whole, hypophosphatemia occurred earlier after thoracic than after cardiac surgery. After thoracic surgery, hypophosphatemia was milder for patients in whom bleeding was more severe. The anticoagulant solution CPD used in stored blood was identified as an important source of phosphate. These results indicate hypophosphatemia is a common finding after cardiothoracic surgery. Since severe hypophosphatemia can be related to phosphate depletion, phosphate supplements could be warranted especially during thoracic surgery when blood transfusions are less than 1000 ml.

[Methionine supplementation in the diet of the pregnant rat. 2. Riboflavin metabolism and hepatic concentration of water, lipid and protein]. / Supplémentation en méthionine du régime alimentaire de la ratte gestante. 2. Métabolisme de la riboflavine et composition hépatique en eau, lipides et protéines.

Dietary addition of methionine suppresses the liver lipidosis in gestating rat fed a diet containing 9% by weight of casein. Riboflavin metabolism is not affected by this addition neither in the dam nor in the newborn rat. Riboflavin content in liver increases in the dam along with the protein content of the diet but does not change in the newborn rat.

[Dietary methionine supplementation in the pregnant rat. 1. Food intake of the dam and body weight of the newborn offspring]. / Supplémentation en méthionine du régime alimentaire de la ratte gestante. 1. Consommation de nourriture de la mère et poids du nouveau-né.

A decrease from 18 to 9% of the dietary casein level induces lower food intake in the gestating female rat and weight loss in the newborn rat. Addition of methionine to the diet containing 9% casein improves food intake in the last period of pregnancy. Body weight of the newborn rat is also increased and becomes identical to that of rats born from mothers fed 18% dietary casein.

[Effect of methionine supplementation of a diet low in riboflavin and at 2 levels of protein on metabolism of riboflavin in the lactating rat]. / Influence de la supplémentation en méthionine d'un régime alimentaire pauvre en riboflavine a 2 niveaux d'apport protéique sur le métabolisme de la riboflavine chez la ratte allaitante.

Lactating female rats were fed diets A or B containing 18 and 12% of casein respectively, or similar diets but supplemented with 0.4% of methionine (diets AM or BM). The animals and their pups were sacrificed at the 18th day of lactation. Control non lactating female rats fed the same diets for the same period of time were also sacrificed. Total riboflavin and its various forms (flavin adenin dinucleotide, flavin mononucleotide + free riboflavin) were measured in various tissues as well as in the milk which was collected from the stomach of the pups after a time controlled suck. In the lactating females fed diets A and B as well as in the control animals fed the same diets the concentrations of riboflavin and of its various forms in plasma, liver and carcass are unchanged. However in group B, they are higher in milk and in tissues of the pups. These results seem to be due to a decrease in food intake by the lactating females fed diet B which results in a decrease in milk production which in turn induces a lower growth rate of the pups although the riboflavin consumption by the latter is unchanged. Addition of methionine to the diet B (diet BM) induces the same effects as diet A which contains the highest amount of proteins but addition of methionine to the diet A (diet AM) has no further incidence. Therefore the present study has not revealed any direct effect of methionine on riboflavin metabolism in lactating female rats and their pups since the effects are similar to an increase of the total protein level in the diet. In both cases they seem to be simply related to an increase of the food consumption.

[Tissue thiamine, riboflavin and vitamin B6 in the aged rat. II. Effects of vitamin supplementation in the diet on the excretion of vitamins and its tissue levels]. / Thiamine, riboflavine et vitamine B6 tissulaires chez le rat agé. II. Influence d'une surcharge vitaminique administrée dans le régime sur l'excrétion des vitamines et sur leurs taux tissulaires.

Nine and twenty-one months old rats fed a balanced diet were given for 5 weeks an extra supplementation in thiamine, riboflavin and vitamin B6. Control animals were given the same diet but without vitamin extra supplementation. Fecal and urinary vitamin excretions were determined during this 5 weeks period. They were shown to be less important in older rats than in younger ones. Influence of aging and vitamin supplementation on the vitamin contents of organs and tissues were studied on these animals: previous results were confirmed [see LECLERC, Ann. nutrit, Aliment., 1976, 30, 10--25]. From these results and others published elsewhere, it is conclused that in older animals there could be an increased intestinal destruction of the above mentionned vitamin although changes in vitamin metabolism can be involved too.

[Thiamine, riboflavin and vitamin B6 contents of organs in the aged rat. I. Effect of vitamin supplementation administered in drinking water]. / Thiamine, riboflavine et vitamine B6 tissulaires chez le rat agé. I--Influence d'une surcharge vitaminique administrée dans l'eau de boisson.

Respectualy ten and twenty-two months old rats, fed an equilibrated diet, were given daily and for one month an extra supplementation of thiamine, riboflavin and vitamin B6 in drinking water. Control animals of the same age were fed identical diets but without vitamin extra supplementation. Vitamin contents of organs (liver, heart, kidneys, spleen, lungs, brain) were determined in order to evaluate both the influence of aging and of vitamin supplementation. Twenty-three months old rats show lower values of thiamin contents (except in liver and brain), riboflavin contents (except in heart and spleen) and vitamin B6 contents (except in heart, lungs and brain) than younger rats. Vitamin extra-supplementation reduces some of these differences: thiamine contents in heart, kidneys and spleen, riboflavin contents in brain, vitamin B6 contents in kidneys and spleen. In all other cases, the extra-supplementation has no effect. Therefore, it seems that the decrease in vitamin contents in organs of old rats is, in many cases an unavoidable consequence of aging.

[Influence of protein-enriched food on tissue vitamin content in pregnant and lactating rats]. / Influence d'un enrichissement de la ration alimentaire en protéines sur certaines teneurs vitaminiques tissulaires chez la ratte gestante et lactante

Two groups of female rats were fed, during gestation and until weaning of their pups, diets containing respectively 18% (normal protein diet) and 27% (high protein diet) by weight of casein. Two control groups of female rats were fed the same diet. Thiamin, riboflavin and vitamin B6 contents were measured in: - liver and carcass of the mothers before and immediately after delivery or at weaning (21st day), - whole body of the new born rats or in liver and carcass of 21 days old pups. - liver and carcass of the control animals. The high protein diet, as compared to the normal diet, gives the following results: 1) There is no variation of the thiamin content in control animals, female rats at delivery, new born rats. However, at weaning, carcasses of mothers and pups (mainly liver) are enriched in thiamin. 2) On the other hand, riboflavin content in tissues increases in control animals (liver and carcass), in mothers before and after delivery (carcass) but particularly in mothers at the end of lactation (liver and carcass) and it is also the case with pups at weaning (carcass). Only in new born rats do both diets have the same effect. 3)The influence of the high protein diet on vitamin B6 content in tissues is complex. The content is not modified in control animals, in mothers at delivery and in new born rats. At the end of lactation (mothers) and at weaning (pups), the vitamin B6 content increases in liver but strongly decreases in carcass.