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Biomedical subjects

D Richard

Publications and source records attributed to D Richard.

At least 163 records · Page 9Linked to original sources
PubMed1986

[Anti LAV/HTLV III antibodies in blood donors: preliminary results of pool screening of 5 samples].

Serological performances obtained with five reagents for anti-LAV/HTLVIII antibody screening were compared in individual test and in pool. A panel of 55 selected samples and 2,079 pools prepared from 10,395 unselected samples of blood donors was studied. A first dilution is achieved by pooling, then a second dilution allows to obtain the exact working dilution recommended for the test. The sensitivity in pool method is always similar to the sensitivity in individual test, no false negative was observed. The specificity, evaluated on unselected samples, is slightly inferior to that observed in individual test: false-positive rate is in generally less than 3% compared to 2% average rate routinely observed with individual test. These results allow to propose this method, which save about 75% of the reagent cost, for blood donor screening in all laboratories and especially in developing countries.

Antibodies, Viral↗
PubMed1986

Exercise suppression of thermoregulatory thermogenesis in warm- and cold-acclimated rats.

An evaluation was made of the effects of an acute exercise bout on nonshivering thermogenesis (NST) in cold-acclimated rats (4 degrees C for 6 weeks) and shivering thermogenesis in 24 degrees C-acclimated rats (24 degrees C for 6 weeks). Assessment techniques included indirect calorimetry during treadmill running and brown adipose tissue (BAT) mitochondrial guanosine diphosphate (GDP) binding immediately following a treadmill run. Calorimetric results for 24 degrees C-acclimated rats running at 4 degrees C indicated total substitution of shivering thermogenesis by exercise-derived heat. No difference in GDP-binding, an index of BAT nonshivering thermogenic activity, was observed between exercised and nonexercised 24 degrees C-acclimated rats. Calorimetric results for cold-acclimated rats running at 4 degrees C indicated a total suppression in the energy cost associated with NST, exercise-derived heat replacing or substituting for NST. Examining BAT properties in the exercised cold-acclimated rats revealed a significant 40% decrease in BAT mitochondrial GDP-binding. These results suggest that during running, metabolic heat due to the exercise totally replaces shivering in 24 degrees C-acclimated rats and totally replaces BAT nonshivering thermogenesis in cold-acclimated rats.

Acclimatization↗
PubMed1986

Thermogenesis in response to various intakes of palatable food.

Complete energy balance studies were made on groups of overfed (A) and underfed (B) Wistar rats. In experiment A one group was fed cafeteria diet ad libitum (the intake was 29% larger than the control), two other groups were fed the same diet but in restricted quantities (18 and 9% above control), and a fourth group, fed a stock diet, served as control. In experiment B, caloric intake was restricted by 12 and 31% in two groups fed cafeteria diet, and by 21 and 34% in two other groups fed stock diet. The experiments lasted 41 days and during that period the protein gain was comparable between the control and the cafeteria-29% group (643.4 +/- 33.3 vs. 578.1 +/- 25.0) but the fat gain was significantly different between the two groups (863.2 +/- 81.6 vs. 1663.2 +/- 99.8 kJ). When energy expenditure (EE) (metabolizable energy less storage added to the cost of storage) is expressed as a percentage of metabolizable energy (ME) intake no significant difference was found among the groups. The average value was congruent to 75%. This finding would not support the presence of dietary-induced thermogenesis in animals overfed on the cafeteria diet. However, since the obligatory cost associated with storing energy would not explain the higher EE of the overfed groups, it is suggested that the level of ME intake exerts continuous proportional regulatory action on EE and, as a result, energy is spared by underfeeding and it is wasted by overfeeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue, Brown↗
PubMed1986

Lipoprotein lipase in adipose tissues of exercise-trained, cold-acclimated rats.

The combined effects of exercise training and cold acclimation on serum lipids and on the activity of lipoprotein lipase (LPL) in epididymal white (WAT) and interscapular brown adipose tissues (BAT) of the rat were evaluated. Sedentary and exercise-trained (treadmill) rats were housed and trained at either 24 or 4 degrees C for 45 days. Although neither treatment given alone influenced serum total cholesterol, exercise training in the cold resulted in a 54% increase in this variable. Serum triglycerides were lowered to 80% of control values by exercise training and to 44% of control by cold acclimation. Both treatments resulted in lower insulin and thyroxine concentrations, while triiodothyronine levels were unaffected. Total LPL activity in WAT was increased twofold by exercise training at both temperatures, whereas cold acclimation stimulated WAT LPL activity to a lesser extent. Exercise training had no overall effect on LPL activity of BAT, whereas cold acclimation increased the latter in both sedentary (217%) and trained (420%) animals. These results emphasize the potential importance of LPL-mediated lipid assimilation in the metabolic events that lead to energy production in response to environmental stresses and lend support to the notion that the regulation of LPL activity is tissue specific.

Acclimatization↗
PubMed1986

Effects of ovarian hormones on energy balance and brown adipose tissue thermogenesis.

This study was carried out to investigate the nutritional energetics of ovariectomized rats with or without ovarian hormone replacement. Rats were divided into five groups: 1) sham operated, 2) ovariectomized, 3) ovariectomized and treated with progesterone, 4) ovariectomized and treated with estradiol, or 5) ovariectomized and treated with estradiol and progesterone. After 36 days of treatment, energy contents of all five groups were determined together with energy content of food and feces. Brown adipose tissue thermogenesis was assessed through mitochondrial GDP binding assay. Results show that ovariectomy leads to a 16% increase in metabolizable energy intake. This increase was accompanied by a twofold increase in body energy gain. Progesterone did not further affect energy intake and gain in ovariectomized rats. However, increases in both food intake and energy gain were prevented by the estradiol replacement therapy. There was no difference in energy expenditure between sham-operated and ovariectomized rats in the absence of estradiol. In estradiol-treated animals, energy expenditure (kJ.kg body wt-0.75 . day-1) showed a slight increase. There was no difference in protein content of interscapular brown adipose tissue between all five groups. GDP binding was slightly reduced in ovariectomized estradiol-treated rats. It is concluded from this study that ovarian hormones produce their effects on energy balance mainly by altering food intake.

Adipose Tissue, Brown↗
PubMed1986

Energy balance in exercise-trained rats acclimated at two environmental temperatures.

The present study was carried out to investigate the effects of exercise training on energy balance in male rats acclimated at two different environmental temperatures. Sedimentary and exercised rats were housed and trained at either 24 or 4 degrees C, with the training program consisting of running on a motor-driven treadmill within their respective environments. After 45 days, energy, protein, and fat contents of rats were determined together with the energy content of food and feces. The results show that metabolizable energy intake was reduced by 10% in exercise-trained groups. Substantial differences in energy gains were observed between sedentary and trained rats; sedentary rats showed almost three times more energy gain than trained rats. Carcass analysis revealed the energy gain differences to be mainly due to varied amounts of fat deposition. Energy expenditure (kJ) excluding the cost of exercise training was corrected for metabolic body size (BW 0.75), which in turn showed no significant differences between trained rats and their respective sedentary controls. The present results suggested that exercise training in rats leads to neither increase nor decrease in energy expenditure through components additional to physical activity. The present results also indicated that brown adipose tissue thermogenesis, as assessed through mitochondrial guanosine 5'-diphosphate binding, was not significantly modified by exercise training, regardless of the temperature at which the rats were housed and trained.

Acclimatization↗
PubMed1986

Brown adipose tissue thermogenesis during pregnancy in mice.

The thermogenic activity of interscapular brown adipose tissue has been assessed at different stages of pregnancy in mice. In late pregnancy there was a hypertrophy of the tissue which reversed at parturition. Neither the total protein content nor the total cytochrome oxidase activity of the tissue changed significantly throughout pregnancy or into early lactation (2-3 days, post-partum). However, mitochondrial GDP binding, an index of the activity of the proton conductance pathway, was significantly decreased at the end of pregnancy with a further decrease in early lactation. Moderate food restriction had no effect on either cytochrome oxidase activity or mitochondrial GDP binding at the end of pregnancy, as compared with pregnant animals fed ad libitum. Food restriction did, however, prevent the hypertrophy of brown adipose tissue in late pregnancy. It is concluded that brown adipose tissue thermogenesis is not significantly decreased in the pregnant mouse until shortly before parturition, even in animals subject to food restriction. It is also concluded that the normal dietary stimulation of thermogenesis in response to hyperphagia is suppressed in the pregnant animal.

Adipose Tissue, Brown↗
PubMed1985

Energetic efficiency during pregnancy in mice fed ad libitum or pair-fed to the normal energy intake of unmated animals.

The energetic efficiency of pregnant mice pair-fed to the ad libitum energy intake of unmated mice or given unrestricted access to food was investigated. Mice were divided into three groups of similar mean body weight, and two groups were then mated, with the third serving as unmated controls. After d 19 of pregnancy the energy content of all three groups was determined, together with the energy content of the food and feces. Both groups of pregnant mice showed a considerable increase in body weight but the weight gain of the pair-fed group was less than that of the mice fed ad libitum. There was a substantial difference in energy gain and gross efficiency between the two pregnant groups, both parameters being almost zero in the pair-fed mice. Only the pregnant mice fed ad libitum showed a higher energy gain and a higher gross efficiency than the nonpregnant mice, and approximately half of the extra energy intake of the pregnant mice fed ad libitum was deposited. The difference in energy gain between the ad libitum-fed and pair-fed pregnant groups was entirely accounted for by differences in maternal energy stores; there was no difference in the number of fetuses nor their energy density. It is concluded from the present study that there is no increase in overall energetic efficiency in pregnant mice restricted to the normal energy intake of nonpregnant animals; the increase in gross efficiency seen in pregnant mice fed ad libitum in associated with their increased energy intake.

Animal Nutritional Physiological Phenomena↗
PubMed1984

Effect of exercise training on the rates of fatty acid synthesis in mice.

The present study has investigated the respective effects of training and exercise on the rates of fatty acid synthesis in mice. Male C57B1 10ScSn mice were trained by forced swimming in a tank at 36 degrees C for 2 h each day for a 28-day period. Rates of fatty acid synthesis were determined in vivo by measuring the incorporation of tritium from 3H2O into tissue fatty acids. At the end of the training programme, both sedentary and trained mice were assigned to either exercising or resting groups. The results obtained show that both training and exercise affected the rates of fatty acid synthesis, regardless of whether the results are expressed per gram of tissue or per whole tissue. Training led to significant decreases in the rates of synthesis in the liver, interscapular brown adipose tissue, epididymal white adipose tissue, and the remaining carcass, particularly in resting mice. The rates of fatty acid synthesis in the major lipogenic tissues were also lower during exercise than under sedentary conditions. The reduction in synthesis in brown adipose tissue was noteworthy in view of the high capacity of this tissue for fatty acid synthesis. In conclusion, it is suggested that in exercise-trained mice carbohydrate is shunted away from the synthesis of lipid in favour of energy storage as glycogen.

Adipose Tissue↗
PubMed1984

Evaluation of pyridoxine intake and pyridoxine status among aged institutionalised people.

The vitamin B6 status of 60 institutionalised elderly subjects (group A: 31 men, mean age = 77 yr and 29 women, mean age = 84 yr) and 41 healthy young adults (group B or control group: 18 men, mean age = 30 yr and 23 women, mean age = 27 yr) was evaluated using erythrocyte aspartate aminotransferase activity coefficient (alpha EGOT) and plasma pyridoxal phosphate (PLP) level (vitamin B6-deficient subjects = alpha greater than 2.0 and PLP less than 80 nmol/l). The kilocalorie, protein and pyridoxine intakes were also estimated. Regarding calories and protein, the diets may be generally considered satisfactory in respect to the French 1981 RDA. The mean dietary intake of vitamin B6 was less than 2 mg/day in all groups. Ninety per cent of the aged, 80 per cent of females in group B in contrast to 56 per cent of males in group B consumed less than their individual vitamin B6 requirements as determined by a probability method. As the incidence of vitamin B6 biochemical deficiency was much higher in the group A (71% for males and 86% for females) than in the control group (11% for males and 30% for females), it is concluded that the high incidence of biochemical vitamin B6 deficiency noted in the aged appeared more relevant from an altered metabolism of the vitamin than from a too low energy intake. Supplements with high doses of vitamin B6 to aged subjects caused a significant decrease in alpha EGOT and a significant increase in PLP levels.

Adult↗
PubMed1983

Effect of acclimation temperature on the concentration of the mitochondrial 'uncoupling' protein measured by radioimmunoassay in mouse brown adipose tissue.

The effect of acclimation temperature on the concentration of the mitochondrial 'uncoupling' protein (Mr 32000) from brown adipose tissue of mice has been investigated. The uncoupling protein was measured by a specific radioimmunoassay. Between 33 degrees C (thermoneutrality) and -2 degrees C there was a progressive increase with decreasing environmental temperature in the amount of uncoupling protein. For mice at -2 degrees C the mitochondrial concentration of the protein was 9-times higher than at 33 degrees C, while the total amount of the protein in interscapular brown adipose tissue was estimated to be nearly 80-times greater at -2 degrees C compared to 33 degrees C.

Acclimatization↗
PubMed1983

Optokinetic nystagmus in the pigeon (Columba livia). II. Role of the pretectal nucleus of the accessory optic system (AOS).

In birds, the accessory optic system (AOS) includes two nuclei: the nucleus ectomamillaris (nEM) and the pretectal nucleus superficialis synencephali (nSS). The role of the nSS in the production of a horizontal optokinetic nystagmus (OKN) was studied in the pigeon, by comparing the OKN before and after a unilateral lesion of this nucleus. The lesions were performed either by electrolysis or by local application of kainic acid (KA); the KA lesions gave more stable modifications of the OKN than the electrolytic lesions. A quantitative analysis of the slow-phase velocity (V) of the OKN was carried out on the animals receiving KA lesions. Lesion of the nSS provokes the almost total disappearance of the OKN for stimulation of the contralateral eye in the temporo-nasal direction, and a reduction of the OKN for stimulation in the naso-temporal direction. Thus, the nSS is essential for the production of the OKN in the temporo-nasal direction, but it also participates in the production of the OKN in the naso-temporal direction (slow-phase direction). The same lesion produces a large increase of the OKN (V) when the ipsilateral eye is stimulated in the temporo-nasal direction, and a smaller increase following stimulation in the naso-temporal direction. These increases suggest some kind of inhibitory (or disfacilitatory) interactions between the nSS (or the associated system) on one side, and the contralateral optokinetic centers. The lesion of one nSS does not provoke a deficit when the stimulation is binocular. This result probably reflects the combined effect of both monocular inputs. After a pretectal KA injection, a spontaneous nystagmus of the contralateral eye, in the naso-temporal direction, can be seen for several hours. The mechanism is still unknown, but it might be related to a reverse optokinetic after nystagmus (R-OKAN). The anatomical and physiological data so far available consistently support the hypothesis of a functional equivalence between the nSS in birds and the nucleus of the optic tract in mammals.

Animals↗
PubMed1983

Adaptive changes in the concentration of the mitochondrial 'uncoupling' protein in brown adipose tissue of hamsters acclimated at different temperatures.

The effect of acclimation at different temperatures on the activity of interscapular brown adipose tissue has been investigated in the hamster, a hibernator. Between 31 degrees and 4 degrees C the cytochrome oxidase activity of the tissue increased 4- to 5-fold, mitochondrial GDP binding per mg of mitochondrial protein doubled, and the amount of uncoupling protein rose from 1.7% to 5.4% of total mitochondrial protein. It is concluded that there are clear adaptive changes induced by temperature in brown adipose tissue of the hamster, but the changes are limited in comparison with those in the mouse.

Acclimatization↗
PubMed1983

Daily variations of plasma glucose and insulin in physically-trained and sedentary subjects.

The variations in plasma glucose and insulin levels were measured at 30-minute intervals throughout the day in physically trained and in sedentary subjects. The subjects exercised for 75 minutes at 65% of VO2max in the first experiment and refrained from heavy exercise in the second experiment. In all situations the physically trained subjects overall had lower plasma glucose and insulin levels than the nontrained subjects. In addition, the positive correlation between plasma glucose and plasma insulin levels observed in the physically trained subjects was significantly smaller than that note in the nontrained subjects, indicating reduced insulin requirements in physically-trained persons. During the period of exercise, glucose levels increased significantly in the trained subjects only. In the period that followed exercise, that is between 1:30 PM and 9:00 PM, the physically trained subjects had plasma glucose levels that were higher than those noted during the comparable hours not preceded by exercise; no comparable difference were found with insulin. Calculation of the total area for insulin indicated a reduction of insulin requirement of about 40% associated with physical training.

Adult↗
PubMed1983

Influence of a palatable, high-fat diet, and exercise training on the high-density lipoprotein to total cholesterol ratio in the rat.

The influence of a palatable, high-energy diet, and exercise training on the levels of serum total cholesterol (CHOL) and CHOL carried by high-density lipoproteins (HDL CHOL) was investigated. Female rats were fed either a laboratory chow or a diet made of palatable food items containing a high level of fat. The animals receiving the latter were divided into groups fed either ad libitum, or pair-fed, on a calorie basis, with the chow-fed animals. Half of the animals were submitted to a swimming program for 4 wk. Body weight, total and HDL CHOL were measured at the end of the treatments. Exercise-trained rats ingested the same amount of calories as their sedentary counterparts, while the animals fed with high-energy diet ate almost twice as many calories as the chow-fed groups. The sedentary animals fed the palatable diet had higher body weights than the chow-fed animals, and exercise prevented this weight increase. Exercise did not have any significant effect on serum total CHOL, but increased significantly the HDL/total CHOL ratio by 15% in the chow-fed animals. The palatable diet increased total CHOL, and decreased the HDL/total CHOL ratio in sedentary animals, whereas the ratio in their trained counterparts was comparable to that of the sedentary chow-fed group. Exercise can thus prevent both weight gain and a decrease in HDL/total CHOL ratio produced by a palatable, high-energy diet in the female rat.

Animals↗