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Biomedical subjects

J Leblanc

Publications and source records attributed to J Leblanc.

At least 55 records · Page 3Linked to original sources
PubMed1983

Limitation of access to highly palatable foods increases the norepinephrine content of many discrete hypothalamic and amygdaloidal nuclei of rat brain.

The norepinephrine (NE) concentration of 14 discrete brain nuclei of rats fed with either purina rat chow or highly palatable foods, given ad libitum or in a restricted quantity isocaloric with the Purina rat chow diet, was measured by high performance liquid chromatography with electrochemical detection. The NE level was significantly increased in the n. suprachiasmaticus, n. paraventricularis, n. arcuatus and n. amygdaloideus (medialis, corticalis, centralis, basalis pars lateralis, lateralis pars posterior) of rats fed with palatable foods given in restricted amount. The increased NE level seems to be associated with the limitation of access to highly palatable food whilst the regimen composition and the palatability of foods are not implicated in this phenomenon. Some hypothalamic and amygdaloid NE-containing neurones can be affected by food-restriction stress, suggesting a role of this neuronal system in feeding activity.

Amygdala↗
PubMed1983

Physiological conflict in humans: fatigue vs. cold discomfort.

Six male human subjects were placed in a situation of physiological conflict, fatigue vs. cold discomfort. Dressed in swim suits and shoes they walked at 3 km X h-1 on a treadmill placed in a climatic chamber. The slope of the treadmill was varied from 0 to 24% and the ambient temperature (Ta) from 25 to 5 degrees C. The subjects could choose Ta when slope was imposed or the converse. They rated pleasure and displeasure of Ta and exercise. Deep body temperature and heart rate were monitored. The results show that the subjects adjusted their behavior to maintain approximatively steady deep body temperature and to limit heart rate below 120 beats X min-1. The physiological compromise was thus correlated to the drive for maximal pleasure-minimal displeasure in the two sensory dimensions fatigue and discomfort.

Adult↗
PubMed1983

Familial resemblance in catecholamine changes to cold stress and maximal exercise.

Parents and children from 38 families were submitted to a cold-stress and maximal treadmill test. The number of subjects varied depending on the measurements. Plasma epinephrine and norepinephrine, blood pressure and heart rate were measured before, during and after a cold hand immersion test (in a water bath at 5 degrees C for 2 min), as well as before and after maximal exercise (modified Balke). Scores were adjusted for the effects of age and sex through multiple-regression procedures (age + sex + age X sex + age2 + age3), yielding residuals which were submitted to analysis. Characteristic variations during cold stress were observed. Maximal exercise yielded a mean aerobic power of 43 ml/kg min-1 (SD = 10), a mean maximal heart rate of 192 (SD = 10) and a mean maximal blood lactate of 65 mg/100 ml (SD = 23). Family resemblances in cold stress and maximal exercise adaptive reactions were investigated by comparison of between-family over within-family means of squares. In response to the cold stress, there were indications of family lines in induced changes for systolic blood pressure, epinephrine, and total catecholamines at 1 min after the test (p less than or equal to 0.05). Furthermore, parent-child correlations were significant and reached 0.38 for epinephrine, 0.28 for norepinephrine, and 0.34 for total catecholamines. Familial concentrations could not be detected before or 8 min after the cold stress. There are no indications of family resemblance in plasma catecholamine concentrations following exposure to maximal-exercise stress. It is concluded that genetic variation is probably contributing only moderately to catecholamine changes under cold stress and very little under exercise stress.

Adolescent↗
PubMed1982

Effect of diet and exercise on norepinephrine-induced thermogenesis in male and female rats.

Male and female rats were fed standard laboratory chow or a highly palatable diet (cafeteria diet) for 10 wk. The cafeteria diet caused an increase in caloric intake and in body weight, and it induced thermogenesis that was associated with elevated plasma triiodothyronine (T3) levels, increased brown adipose tissue size, and enhanced metabolic response to norepinephrine. For a comparable caloric intake, body-weight gain was significantly greater in female than in male rats possibly because of difference in thermogenesis as suggested by the response to norepinephrine. Exercise training (swimming 2 h/day for 10 wk) reduced food intake and body-weight gain and failed to increase norepinephrine-induced thermogenesis in rats fed laboratory chow. In animals fed the cafeteria diet, food intake and body-weight gain were also reduced by exercise training, which at the same time diminished the diet-induced thermogenesis as evidenced by the diminution of 1) brown fat hypertrophy, 2) the elevation of plasma T3, and 3) the hyperthermic response to injected norepinephrine. It is suggested that the thyroid hormone and catecholamines through their actions on the brown adipose tissue are the important regulatory of thermogenesis. Exercise training would reduce the diet-induced thermogenesis by preventing increased T3 production. Enhanced thermogenesis may be considered an adaptive reaction as it serves to reduce fat deposition in animals fed cafeteria diet and to promote nonshivering heat production in the cold. On the other hand, exercise training reduces thermogenesis and thus prevents energy wasting.

Adipose Tissue↗
PubMed1981

A manual semi-micro method for quantitation of haemagglutination.

A manual semi-micro method for quantitation of haemagglutination is described. It appears to be of wide use for most agglutination reactions usually performed in test tube, including Coombs-test. It is easy to handle and requires the usual equipment of an immunohaematological laboratory. The accuracy obtained for quantitation of antibody concentrations is similar to that of the auto-analyser.

Autoanalysis↗
PubMed1981

Protein synthesis, amino acid uptake, and pools during isoproterenol-induced hypertrophy of the rat heart and tibialis muscle.

Chronic administration of isoproterenol (ISO) produces hypertrophy of the rat heart and tibialis muscle. With doses of 0.1, 0.3, and 0.6 mg/kg, hypertrophy of the heart is significantly by the 3rd day of treatment. Maximum cardiac enlargement attained with doses of 0.3 and 0.6 mg/kg occurs after 21 days and averages 40% above control values. ISO increases tibialis muscle weight by 15%. Incorporation of 14C-labeled amino acids into total heart and tibialis muscle protein is stimulated by ISO. Maximum stimulation occurs 2-3 h after the fifth daily injection of ISO. The stimulation of incorporation is greater during the first few days of treatment and decreases gradually thereafter. A single injection of ISO decreases the total amino acid concentration of the serum, heart and tibialis muscle whereas the rate of amino acid uptake by the heart and tibialis muscle is increased by ISO. The production of hypertrophy of the heart and tibialis muscle in diabetic or castrated animals by ISO suggests that insulin and testosterone are not essential in the mechanism of ISO-induced hypertrophy.

Amino Acids↗
PubMed1980

Transaxillary pleurectomy for treatment of spontaneous pneumothorax.

In the 16-year period 1962 to 1978, 409 transaxillary apical pleurectomies were carried out for definitive treatment of spontaneous pneumothorax in 362 patients. Surgical indications included recurrence (336), bilaterality of the disease (23), persistent air leak (22), and nonexpansion of the lung (10). There was 1 operative death (unsuspected brain tumor), and 3 patients required reexploration for clot removal. The average postoperative period of hospitalization was 6 days. Three hundred ten patients (86% of all patients) were contacted for follow-up 1 to 16 years after operation (average, 4.5 years). There were two documented episodes of recurrent ipsilateral pneumothorax (0.6%). Postoperative pulmonary function studies were done in 40 patients (unilateral, 29; bilateral, 11) 2 to 5 years after operation. The results indicate that there are no significant abnormalities compared with predicted values.

Adolescent↗
PubMed1975

Nonshivering thermogenesis and cold resistance in rats under severe cold conditions.

Following either chronic exposure to 6 degrees C, or outdoor winter exposure, or chronic treatment with tyramine rats were exposed to -40 degrees C and their oxygen consumption and colonic temperature monitored. Fall in body temperature with time of exposure followed a sigmoid curve which had an inflection point around 32.9 degrees C. Both the time required for body temperature to reach this point and hypothermic resistance defined as the total O2 consumed up to the inflection time were useful indices of resistance to severe cold; Three days before the cold tests, capacity for norepinephrine-induced nonshivering thermogenesis was measured in all animals by examination of their metabolic response to tyraminemthe magnitude of response to tyramine correlated well with hypothermic resistance only for those rats chroncally treated with tyramine. It is concluded that it is impossible to predict with any reasonable degree of confidence the cold resistance of a rat from its tyramine response. In cold-acclimated rats, factors in addition to norepinephrine sensitivity are significantly involved in cold resistance and deserve further studies.

Acclimatization↗