Search PubMed⌕ Search

Biomedical subjects

D Ricquier

Publications and source records attributed to D Ricquier.

156 records · Page 9Linked to original sources
PubMed1979

Changes induced by cold adaptation in the brown adipose tissue from several species of rodents, with special reference to the mitochondrial components.

(1) The effects of cold adaptation upon the brown adipose tissue have been studied in rats, hamsters, mice, and guinea pigs. (2) Striking effects were found for total tissue as well as at the mitochondrial level, e.g., increases in protein and phospholipid contents, changes in phospholipid fatty acid composition (a decrease in the percentage of palmitic and palmitoleic acids and an increase in stearic and linoleic acids), and a change in the mitochondrial polypeptide composition (a marked increase in a 32000 molecular weight polypeptide, except for hamsters). (3) In situations where animals exhibit a greatly enhanced capacity for nonshivering thermogenesis (cold adaptation for rats, mice, and guinea pigs, birth for guinea pigs, and hibernation ability for hamsters, dormice, and garden dormice), brown fat mitochondria are characterized by the occurrence of large amounts of the 32000 molecular weight polypeptide characteristic of these mitochondria.

Adaptation, Physiological↗
PubMed1978

Effects of cold adaptation and re-adaptation upon the mitochondrial phospholipids of brown adipose tissue.

1. A study of the mitochondrial phospholipids, phospholipid fatty acid patterns and enzyme activities was investigated in brown tissue (B.A.T.) from rats chronically exposed to cold and/or treated with thyroxine. 2. The total activities of the oxidative enzymes were increased after cold exposure, but not after thyroxine treatment. 3. Cold exposure increased the amount of phosphatidylethanolamine, phosphatidylcholine, cardiolipin and lysophospholipids, the effect being greatest for phosphatidylethanolamine. At the same time, there were marked alterations in the fatty acid composition of the mitochondrial phospholipids (decrease of palmitic, palmitoleic and oleic acids ; increase of stearic, linoleic and arachidonic acids). 4. All these cold-induced alterations were reversed by re-adaptation of the animal to a normal temperature range. 5. The alterations of the fatty acid composition of phospholipids could be explained by changes in the rate of individual fatty acid biosynthesis.

Adaptation, Physiological↗
PubMed1977

Glycerol metabolism in the pregnant and virgin rats.

The parameters of in vivo glycerol kinetic curves were determined after a single injection of glycerol-1-14 C in pregnant and in virgin rats. The half-life of glycerol was found to be 9 min in pregnant rats and 17 min in virgin rats. There was no significant difference between the absolute turnover rates. The glycerol plasma space cannot be appreciated. The distribution volume expressed in milliliter of plasma appeared to be very high indicating that glycerol was not distributed only in the plasma. Glycerol was found to be a precursor of glucose and this conversion seemed to proceed more rapidly in the pregnant rat than in the virgin rat.

Animals↗
PubMed1976

Effects of chronic treatments upon the brown adipose tissue of young rats. I. Cold exposure and hyperthyroidism.

1. The gross composition, triglycerides and phospholipids of brown adipose tissue were studied in young and adult rats chronically treated with cold or thyroxine. 2. Cold induced an increase of the total water, protein and phospholipid of tissue while the main effect of thyroxine treatment was an accumulation of triglycerides. Thyroxine treatment prevented the cold-induced increase of phospholipid percentage in the tissue. 3. Cold exposure altered the fatty acid pattern of phospholipids, whereas thyroxine had smaller and different effects. 4. The differential effects of cold and hyperthyroidism upon triglycerides and phospholipids of brown adipose tissue are briefly discussed.

Adipose Tissue, Brown↗
PubMed1975

The lipoprotein lipase activity of brown adipose tissue during early post-natal development of the normal and hypothyroid rat.

The heparin-releasable LP lipase activity of BAT (brown adipose tissue), and the TG (triglyceride) content of plasma were determined in normal and hypothyroid rats during early post-natal development. The TG content of plasma increased sharply after the onset of suckling and decreased during the weaning period in normal rats, while it stayed at a high level in hypothyroid rats. LP lipase activity was maximal during the perinatal period and decreased later, being practically undetectable in one month old control animals; in contrast, LP lipase activity was still present in cretin rats at this age. The effects of several forms of treatment were also tested in weaned rats: a high-fat diet was not able to maintain the high LP lipase activity of suckling rats, but the activity was high if the animals were bred at a cold temperature. Thyroxine injections had no effect. These results are discussed in terms of the possible factors regulating the LP lipase activity in BAT.

Adipose Tissue, Brown↗
PubMedDate not supplied

Magnesium and thermoregulation. I. Newborn and infant. Is sudden infant death syndrome a magnesium-dependent disease of the transition from chemical to physical thermoregulation?

The sudden infant death syndrome (SIDS) remains a leading cause of death during the first year. The common epidemiological and pathological data which characterize SIDS include the curve for age at death (with 3 months as modal age), the stigmata of early maternal intrauterine injury, the seasonal predominance in winter, and the absence of an adequate cause of death at autopsy. Some data characterize risk factor subgroups: for example low socioeconomic level, environmental pollution, stress, and mistakes in baby care. Symptoms before death may be lacking, they may be common and non-specific, or rarely they may be acute, corresponding to "apparent life-threatening events" (ALTE). SIDS may be a magnesium-dependent disease of the transition from chemical to physical thermoregulation. This theory originates from a synthesis of our present knowledge of SIDS, maternal magnesium status, and thermoregulation in the baby. It is consistent with all the epidemiological and pathological prerequisites characterizing SIDS. It eliminates the hiatus between relatively minor thermal stress and induced lethal thermal stroke. Logical scepticism about the role of an implausible lethal superacute magnesium deficiency is no longer justified with regard to well established chronic marginal magnesium deficiency. Further experimental and clinical research will be interesting, i.e. ex vivo studies on brown adipose tissue (BAT) and magnesium deficiency under various conditions of thermal exposure. But even now the theory leads to three therapeutic consequences: (1) the need to define the importance of magnesium deficiency in diagnosis and treatment of ALTE; (2) an assessment of the use of new techniques of rewarming (i.e. extracorporeal circulation) in hypothermia cases to distinguish cot death from "apparent death"; (3) investigation of the prevention of SIDS with magnesium through a blinded and randomized multicentre prospective cooperative study of magnesium supplementation in pregnant and lactating women, followed not only in the mother, fetus, and neonate at birth, but also through the first year of life.

Body Temperature Regulation↗
PubMedDate not supplied

[Thermogenesis and obesity: molecular aspects].

The energizing balance of the body is the result of intake and output of energy. Intake corresponds to eating and output corresponds to basal metabolism, physical exercise and heat production. Recent studies conducted on man suggest that obesity could be associated with a lack of heat production. Thus, a decreased thermogenic consumption associated with eating could contribute to the development of obesity. This hypothesis seems valid as far as obese rodents are concerned. In this case, it is a known fact that a specific organ, the brown fatty tissue, main effector of the thermogenesis induced by cold and eating. The molecular mechanisms of heat production by the brown fatty tissue, have been recently explained. Brown adipocytes are present in man, but their specific contribution to the energizing balance or imbalance is not yet established. This will be subject of further studies.

Adipose Tissue, Brown↗