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Biomedical subjects

D Richard

Publications and source records attributed to D Richard.

At least 19 recordsLinked to original sources
PubMed1992

The 5-hydroxytryptamine agonist fenfluramine increases Fos-like immunoreactivity in the brain.

This study was designed to assess the effects of the 5-hydroxytryptamine (5-HT) indirect agonist fenfluramine on the brain distribution of Fos- and corticotropin-releasing factor-like immunoreactivity (F-LI and CRF-LI). A single intraperitoneal injection of either DL-fenfluramine (25 mg/kg) or saline was given to resting Sprague-Dawley rats housed on a 12-12 h light-dark cycle and fed libitum. Sixty min following injections, rats were killed and brains removed and sliced (40 microns thick) in a coronal plane from the anterior olfactory bulb to the brainstem. Brain slices were then stored at -40 degrees C pending the tissue localization of F-LI and CRF-LI. F-LI and CRF-LI were determined by means of a double immunostaining procedure using the peroxidase-avidin:biotin complex (ABC) method. Fenfluramine injection led to a marked increase in F-LI in the caudate-putamen (CPu), the parvocellular division of the hypothalamic paraventricular nucleus (PVN), and the central amygdaloid nucleus (CeA). In the PVN, most of the F-LI was co-localized with CRF-LI. There was no attempt to identify which types of neurons displayed F-LI in CPu and CeA. While F-LI was readily observable in all rats treated with fenfluramine, it was not discernible in the control animals. This study provides evidence for an involvement of the immediate-early genes c-fos in the central action of fenfluramine.

Amygdala↗
PubMed1992

Effects of fasting and food restriction on sympathetic activity in brown adipose tissue in mice.

The activity of the sympathetic nervous system in mice that were either fed ad libitum, food restricted or fasted was estimated by measuring the accumulation of dopamine following the inhibition of dopamine beta-hydroxylase activity. Mice in each group were injected with the dopamine beta-hydroxylase inhibitor 1-cyclohexyl-2-mercaptoimidazole and were exposed to either 30 degrees C (warm) or 4 degrees C (cold). Mice were killed 1 h after the injection. Both heart and brown adipose tissue were then quickly removed and homogenized in ice-cold perchloric acid. Dopamine and noradrenaline were determined using high performance liquid chromatography. Regardless of whether mice were warm or cold exposed, both content and concentration of brown adipose tissue and dopamine were predictably higher in 1-cyclohexyl-2-mercaptoimidazole-injected mice than in non-injected animals. In mice fed ad libitum, post-injection content and concentration of dopamine in both brown adipose tissue and heart were higher in cold-exposed mice than in warm-exposed animals. In food-restricted and fasted mice, post-injection concentrations of dopamine in brown adipose tissue were higher in cold-exposed mice than in warm-exposed animals. In food-restricted and fasted mice there was no difference between warm- and cold-exposed animals with respect to post-injection contents and concentrations of dopamine in heart tissue. In fasted mice there was no difference between warm- and cold-exposed animals in post-injection content of dopamine in brown adipose tissue. This study provides further evidence that fasting, in contrast to food restriction, may blunt the tissue sympathetic nervous system response in brown adipose tissue of cold-exposed mice.

Adipose Tissue, Brown↗
PubMed1992

Adrenalectomy attenuates the effect of chemical castration on energy balance in rats.

The individual and combined influences of castration and adrenalectomy on energy balance in rats were investigated in a 2 x 2 factorial design. Castration was chemically achieved by treating rats with Buserelin, a gonadotropin-releasing hormone (GnRH) agonist. During the treatment, the rats were weighed every 2 or 3 d, and the total amount of food consumed was determined. At the end of the 14-d treatment period, rats were killed and their carcasses were analyzed for protein, fat and energy content. In the sham-operated groups, body weight gain was greater in Buserelin-treated rats than in saline-infused animals. However, in the adrenalectomized rats, there was no difference in body weight gain between the Buserelin- and saline-infused animals. In sham-operated groups, body protein and body fat gains were significantly larger in Buserelinthan in saline-infused animals. In saline-infused groups, protein gain was greater in adrenalectomized than in sham-operated animals. On the other hand, in the Buserelin-infused rats, there was no difference in the protein gain between the adrenalectomized and sham-operated rats. The adrenalectomized groups of rats ate less and deposited less fat and energy than their respective sham-operated counterparts. In the sham-operated groups, both the intake and the gain of energy were larger in the Buserelin-treated than in saline-infused rats. The present study indicates that adrenalectomy can significantly attenuate the influence of castration on energy gain, providing evidence that adrenals and ovaries can interact in the regulation of energy balance.

Adipose Tissue↗
PubMed1992

Tissue specificity of SNS response to exercise in mice exposed to low temperatures.

The present study was carried out to investigate the tissue specificity of the sympathetic nervous system (SNS) response to acute exercise in adult mice exposed to four ambient temperatures. SNS activity estimates in heart, pancreas, and brown adipose tissue (BAT) were obtained from the measurement of the dopamine (DA) tissue contents 1 h after the inhibition of the DA-beta-hydroxylase with 1-cyclohexyl-2-mercaptoimidazole (CHMI). DA was measured by electrochemical detection after the separation of the monoamine using high-performance liquid chromatography. In both heart and pancreas, temperature and activity influenced DA tissue contents after the CHMI injection. In these tissues, and regardless of whether mice were resting or exercising, the DA contents gradually increased while the ambient temperature was dropped from a thermoneutral temperature of 32 to 5 degrees C. In BAT, however, there was a significant interaction between temperature and activity on the tissue DA content; in contrast to what was observed in resting animals, DA did not uniformly augment in exercising mice when the temperature was decreased from 32 to 5 degrees C. In summary, the present results show that exercise can attenuate the stimulating effect of cold on SNS activity in BAT. This effect is seemingly specific to BAT because, in mice exposed to low ambient temperatures, SNS activity in both heart and pancreas is not lower in exercising than in resting animals.

Adipose Tissue, Brown↗
PubMed1992

Synaptic activation of rat supraoptic neurons by osmotic stimulation of the organum vasculosum lamina terminalis.

Intracellular recordings were obtained from neurons of the supraoptic nucleus in superfused explants of rat hypothalamus in vitro. Transient hyperosmotic stimulation of the organum vasculosum lamina terminalis (OVLT) area caused long-lasting increases in the frequency of excitatory post-synaptic potentials and an associated rise in the rate of action potential discharge. Such responses could be evoked by small (less than + 2%) increases in osmolality, but not by isotonic solutions. These results suggest that the OVLT plays a functional role in the osmoregulation of neurohypophyseal hormone release.

Action Potentials↗
PubMed1991

Acute ethanol treatment induces a bimodal response of phospholipid acylation rates in rat red blood cells.

A single intraperitoneal injection of ethanol (4 g/kg) in rats elicited a bimodal response of acylation rates in phosphatidylcholine and phosphatidylethanolamine of intact red blood cells. Within an initial period, ethanol inhibited acylation rates. The inhibition then reversed, leading to increased values which persisted as long as ethanol was present in plasma. Acylation rates were not correlated to ethanol concentrations in plasma. We suggest that red cells first desensitize to, then overcompensate for the inhibitory effect of ethanol on acylation reactions. These adaptive changes may be one of the events mediating membrane tolerance to ethanol.

Acylation↗
PubMed1991

Effects of exercise on energy balance in meal-fed mice.

The effects of exercise on energy balance have been investigated in mice accustomed to eating their daily food ration in three meals. A meal period lasts 1 hour, and during that period mice were allowed to eat unrestrictedly a pelleted stock diet. Two series of experiments were conducted. In one series of experiments indirect calorimetric measurements were carried out in untrained mice that were assigned to 3 experimental groups; a first group of mice was allowed to rest; a second group of mice was exercised immediately before one of the 3 meals; a third group of mice was exercised immediately after one of the 3 meals. The exercise bout consisted of 1 hour of forced exercise on a rodent treadmill at a speed of 20 meters per minute. O2 consumption (VO2) and CO2 production were monitored throughout a full day except at the time the exercising animals were on the treadmill. In a second series of experiments long-term energy balance measurements were carried out. Mice were then assigned to experimental conditions similar to those previously described for 31 days during which period food intake and body weight were continuously monitored. At the end of 31 days of experiment, mice were killed, and their carcasses were individually analysed for their contents of energy, fat and protein. Carcass and food gross energy contents were assessed by bomb calorimetry. At the end of the long-term energy balance trial, the percentage of fat, the energy gain, the energy density and the weight of the dry carcass were significantly lower in exercised groups of mice than in the resting group of animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The involvement of the sympathetic nervous system in meal-induced thermogenesis in mice.

The acute effect of food intake on the activity of the sympathetic nervous system (SNS) in both heart and brown adipose tissue (BAT) was investigated in mice. Upon delivery to the laboratory mice were housed singly and divided into two groups. Half the mice were accustomed to eat their daily food ration in two meals whereas the other half were given continuous access to food. SNS activity in both heart and BAT was estimated by measuring the accumulation of dopamine (DA) after having blocked the transformation of dopamine into noradrenaline (NA) with 1-cyclohexyl-2-mercapto-imidazole (CHMI). CHMI inhibits the enzyme dopamine beta-hydroxylase. On the day SNS activity was assessed, continuously fed (CF) or meal-fed (MF) mice were injected with either saline or CHMI one hour before being killed. In order to assess the anticipatory effects of being fed, a group of mice already accustomed to the meal-feeding schedule were not allowed to eat after the injections. Additional CF and MF mice were killed without being injected in order to determine the basal levels of both DA and NA. The results show that the accumulation of DA in both heart and BAT was higher in MF than CF mice regardless of whether MF mice were or were not fed after the injection of CHMI. It therefore appears that the intake of food may increase SNS activity in various tissues in mice, and that such a response may be largely of cephalic origin.

Adipose Tissue↗
PubMed1991

Reversible increase in energy deposition following castration induced by a gonadotropin releasing hormone agonist.

The effects on energy balance of a potent gonadotropin releasing hormone (GnRH) agonist, have been investigated in rats. Female rats initially weighing 180 g were divided into three groups. One group of rats underwent a bilateral ovariectomy whereas the two remaining groups were sham-operated. Rats in one of the two sham-operated groups were treated with Buserelin which was administrated by means of miniosmotic pumps. The remaining rats were implanted with minipumps that delivered saline. After 28 days of treatment, half of the rats in each group were killed by decapitation whereas the remaining animals had their pumps removed so that the Buserelin treatment stopped. The post-treatment lasted 28 days after which period, rats were killed. Body weight and food intake were measured over every 2 or 3 day periods. Carcasses were analyzed for their contents in protein, fat and energy. During the treatment period, rats that were ovariectomized and those treated with Buserelin increased their food intakes and energy depositions. The increase in energy deposition reflected an increase not only in fat but also in protein deposition. During the post-treatment period, metabolizable energy intake of rats that were administered Buserelin returned to the levels of placebo-treated rats. Twenty-eight days post-treatment, the carcass energy contents of the Buserelin-treated rats were no longer different from those of placebo-treated rats. In conclusion, Buserelin induces an increase in energy deposition that is readily reversed upon cessation of the treatment.

Animals↗
PubMed1991

Prevalence of infections and their risk factors in geriatric institutions: a one-day multicentre survey.

This one-day prevalence survey of 1919 patients (74% females and 44% aged greater than or equal to 85 years) in nine geriatric hospitals, six of them located in France and three in Switzerland, indicated a high prevalence of infections in elderly institutionalized patients (infection rate: 18.7% in males and 15.4% in females). The risk factors for infection were identified and the relative risks assessed. Prevention of infections in geriatric wards should be one of the goals of every care-giver. A low rate of infection in elderly inpatients is thus likely to be associated with care of good quality.

Aged↗
PubMed1990

Counterregulatory response to insulin-induced hypoglycemia in trained and nontrained humans.

The aim of the present series of experiments was to investigate the hormonal counterregulatory response to insulin-induced hypoglycemia in trained and nontrained healthy individuals. Five endurance athletes and six controls were administered intravenous insulin infusion at a rate of 0.15 U/kg/h until plasma glucose reached 50 mg/dL. The mean duration of the infusion in the trained and nontrained subjects corresponded to 18.6 and 26.3 minutes (P less than .01), suggesting that the former were characterized by an increased insulin sensitivity. Plasma glucose levels were similar in the two groups at the end of the insulin infusion, as well as during the postinfusion recovery period. Forty-five minutes after the end of the infusion, plasma glucose levels were not significantly different from the preinfusion levels in the two groups. During this period of glycemia recovery, the increases in plasma glucagon, epinephrine, norepinephrine, and growth hormone were at least 50% lower in the trained than in the nontrained subjects. The increase in heart rate and oxygen uptake during the same period of time was significantly higher in the trained subjects. To determine whether this reduced hormonal response to hypoglycemia was due to reduced insulin levels or to an increased sensitivity to counterregulatory hormones, we investigated the effect of epinephrine on plasma glucose in two other groups of trained and nontrained subjects. In response to a constant epinephrine infusion of 0.01 or 0.1 micrograms/kg fat-free mass (FFM)/min, plasma glucose levels increased similarly in the two groups. In conclusion, these results indicate that trained subjects are characterized by a normal recovery from hypoglycemia despite a reduced response of counterregulatory factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Glucose↗
PubMed1990

Involvement of corticotropin-releasing factor in the anorexia induced by exercise.

The role of corticotropin-releasing factor (CRF) in the sex-dependent anorexia induced by exercise was investigated in male Wistar rats. Each rat was implanted with a permanent guide cannula that was stereotaxically positioned close to the right lateral ventricle of the brain. During the recovery period, which lasted 10 days, rats were accustomed to eat three meals per day. The onset of each meal occurred every 8 hours. During a meal, rats were allowed free access to a pelleted stock diet for one hour. Ten days after the surgery, rats were injected in the right lateral ventricle of the brain with either saline or 100 micrograms of alpha-helical CRF (9-41), a selective CRF antagonist. Fifteen minutes after the injections, half of the rats were forced to exercise while the others were allowed to rest. The exercise consisted of a moderately intense period of running on a motor-driven treadmill during 40 minutes. Immediately after the period of exercise, animals were offered food, and the amount eaten during the meal period was carefully measured. The results indicate that the exercised rats ate less food than resting animals when saline was infused prior to subjecting the animals to running. In addition, in saline-treated animals, growth of exercised rats was slower than that of resting rats during the day following exercise. Contrastingly, in rats infused with alpha-helical CRF (9-41) exercise exerted no effect on food intake, neither did it reduce body weight gain of the rats. The present results suggest that CRF plays a major role in the anorexia caused by exercise in male rats.

Animals↗
PubMed1990

Lipoprotein lipase activity in white adipose tissue of rats subjected to exercise--rest cycles.

This study was conducted to determine serum lipid levels and the activity of lipoprotein lipase in epididymal white adipose tissue of rats undergoing exercise training. During the 8-week period of treatment, one group of rats was kept sedentary and the remaining animals were exercise trained either continually (1 h of daily treadmill running) or intermittently (alternate weeks of daily running and inactivity). Exercise training, either continual or intermittent, decreased postprandial serum total and high-density lipoprotein cholesterol concentrations, which returned to sedentary levels in the intermittently trained animals following a week of rest. Lipoprotein lipase activity in whole epididymal adipose pad was lower in rats trained continually than in the sedentary group at the end of the treatment. The intermittent training program elicited large fluctuations in both the specific (per milligram of protein) and total (per tissue) activity of lipoprotein lipase in white adipose tissue. During rest periods, enzyme activity rose to levels that were higher than those of sedentary rats, whereas lipase activity was below that of sedentary animals following a week of running. In the last exercise--rest cycle, body weight gain of the intermittently trained rats was nearly abolished during the week of running, but it increased above that of sedentary animals during weeks of rest. The present results suggest that the modulation of lipoprotein lipase activity in white adipose tissue is one of the adaptations that take place to accommodate the fluctuations in the rate of energy deposition that occur in the rat during an intermittent training program.

Adipose Tissue↗
PubMed1990

Hypothalamic paraventricular nucleus lesions do not prevent anorectic effect of exercise in male rats.

The effects of a hypothalamic paraventricular nucleus (PVN) lesion on energy balance were investigated in exercise-trained rats. Male Wistar rats weighing initially 250 g were divided into four groups. Two groups of rats underwent a bilateral PVN lesion, whereas the two remaining groups were sham operated. The PVN lesions were done electrolytically. One group from each surgical treatment was exercised, while the other group was kept in sedentary conditions. Rats were exercised on a rodent motor-driven treadmill at moderate intensity, 1 h/day for 21 consecutive days. Food intake and body weight were measured each day during the study. At the end of the treatment period, rats were killed, and carcasses were analyzed for their energy content. Serum corticosterone was measured by a competitive protein-binding assay. Energy gain and energy intake were lower in exercised rats than in sedentary controls, regardless of whether they were sham or PVN lesioned. Concurrently, there was no difference in the energy gain between PVN-lesioned and sham-operated rats, despite the fact that PVN-lesioned rats ended the experiment with a larger body weight than the sham-lesioned animals. Serum corticosterone levels were lower in PVN-lesioned rats than in sham-lesioned rats. In conclusion, the present results indicate that the PVN, the hypothalamic nucleus predominantly controlling the pituitary-adrenal axis activity, is not a prominent structure in the regulation of energy balance in exercised male Wistar rats.

Animals↗
PubMed1990

[Chemical composition of feces from bovines, sheep and goats feeding from Sahelo-Sudanese natural or farming fields: its use for estimating the nutritive value of their diet].

The chemical composition of grazing cattle, sheep and goat feces is described according to animal species, type of range (natural pasture or fields after crops) and season in a sub-Sahelian environment. Nutritive value (organic matter digestibility and digestible crude protein) of forages can be estimated from some chemical fecal criteria.

Animal Feed↗
PubMed1990

[Surgical treatment of basocellular carcinoma of the auricular concha. Our experiences apropos of 11 cases].

Next to an anatomical come back authors describe different surgical technics they used for the rebuilding of the ear concha, after exeresis of basal cells epitheliomas: Post auricular island flap. Pretragian flaps superior pedicle. Post auricular flaps with a superior pedicle in two or one time. Clinical cases show what they said. To conclude, authors insist on the advantages of surgery: It allows, in the "conchal area" a protection of contiguous cartilage, in addition to a total check-up of the tumor. Surgical treatment can also be used to correct failures or resumption after radiotherapy.

Aged↗
PubMed1989

The role of exercise in thermogenesis and energy balance.

The role of exercise training in energy balance has been reviewed. Recent well-conducted studies showed that exercise may increase energy expenditure not only during the period of exercise itself but during the postexercise period as well. This notion of excess postexercise oxygen consumption (EPOC), which has been a controversial issue for many years, is now becoming a generally well-accepted concept, the consensus being that EPOC takes place following prolonged and strenuous exercise bouts. Besides, the role of EPOC in long-term energy balance remains to be determined. Long-term energy balance studies carried out in rats show that exercise affects energy balance by altering food intake and promoting energy expenditure. In male rats exercise causes a marked decrease in energy intake which contributes, in association with the expenditure of exercise itself, to retard lean and fat tissue growth. From the suppressed deposition of lean body mass, decreases in basal metabolic rate can be predicted in males. In female rats, exercise does not affect food intake; the lower energy gain of exercise-trained females results from the elevated expenditure rate associated with exercise itself. In both male and female rats, there is no evidence that exercise training affects energy expenditure other than during exercise itself unless the habitual feeding pattern of the rats is radically modified. The interactive effects of diet and exercise, which have to be further investigated in long-term energy balance, emerge as a promising area of research.

Animals↗