Biomedical subjects

J LeBlanc

Publications and source records attributed to J LeBlanc.

At least 73 records · Page 4Linked to original sources

PubMed1984

Diet-induced thermogenesis with relation to training state in female subjects.

The purpose of this study was to investigate the effect of exercise training on meal-induced thermogenesis in 30 female subjects with an average age of 26 years, an average weight of 53.5 kg, and an average height of 162.4 cm. Three groups of 10 subjects were formed with an average maximum aerobic capacity (VO2max) of 57.5 mL X kg-1 X min-1 and a percent body fat of 17.5% for group 1 (competition athletes), of 49.9 mL X kg-1 X min-1 and 21.2% for group 2 (moderately active), and 38.9 mL X kg-1 X min-1 and 22.2% for group 3 (sedentary subjects). Oxygen uptake (VO2), respiratory quotient (R), and heart rate (HR) were measured at intervals for 45 min before and 120 min after a standard meal containing 800 kCal (1 kCal = 4.184 kJ). The increases in VO2 produced by the meal were significantly smaller (P less than 0.05) in group 1 than in group 3. Following the meal, R was significantly increased (P less than 0.01) from its initial value in the three groups, but it remained significantly lower in the well-trained subjects than in the nontrained. HR, which was initially higher (P less than 0.01) in group 3, was slightly increased after the meal, but the response was the same for all groups. These results show a diminished meal-induced thermogenesis in exercise-trained female subjects associated with reduced carbohydrate oxidation.

Adult↗

PubMed1984

Reduced postprandial heat production with gavage as compared with meal feeding in human subjects.

The postprandial changes in resting metabolic rate (RMR) were measured in eight subjects after the ingestion of 735 kcal taken in the form of a meal or fed by stomach tube. A much larger increase in RMR was found with meal feeding (MF) as compared with tube feeding (TF). Measurements of respiratory quotient (RQ) indicated that the increase in RMR with MF is related to increased glucose oxidation, whereas with TF it is possibly explained primarily by the cost of energy storing. Determination of plasma norepinephrine (NE) indicated that the sympathetic nervous system is activated by MF but not by TF. Similarly, plasma glucose and insulin determinations have shown that the secretion of insulin is increased during food ingestion but only with the MF situation. Thus in the 30 min after the beginning of the meal, an increased glucose oxidation was observed that is possibly related to an enhanced NE and insulin secretion; such effects were nonexistent in the TF situation. These results would not substantiate the notion of the specific dynamic action of food and would indicate that independent of the composition of the ingested nutrients, the postprandial increase in RMR is also influenced by sensory and cognitive stimulations.

Adult↗

PubMed1984

Hormonal factors in reduced postprandial heat production of exercise-trained subjects.

The influence of exercise training on postprandial heat production was investigated in human subjects. Whereas resting metabolic rate was comparable for trained and nontrained subjects, the heat increment of feeding (HIF) after subjects consumed a meal containing 755 kcal was approximately 50% smaller in the trained subjects. Measurements of respiratory quotient also indicated a reduction of about 50% in glucose oxidation associated with exercise training. The levels of plasma norepinephrine increased significantly (P less than 0.01) from 200 to 300 pg/ml in the sedentary subjects, but the changes observed in trained subjects were not significant. During the early phase of the meal, plasma levels of insulin were increased, even before nutrients appeared in the blood. Throughout the study the enhanced sensitivity to insulin of the trained subjects was confirmed. the postprandial heat production was diminished in exercise-trained subjects, and it is suggested that this could be related to a reduced activity of the sympathetic nervous system. Another possibility is that this reduction in HIF is related to a facilitation of glucose disposal in the form of glycogen rather than in the form of lipids.

Adult↗

PubMed1984

Subclavian arterioplasty. Repair of coarctation of the aorta in the first year of life.

Between June, 1977, and December, 1982, 106 infants underwent subclavian flap arterioplasty for repair of coarctation of the aorta in the first year of life. This technique was utilized because of our previous experience with the end-to-end technique in 181 infants, in whom there was a recurrence rate of 42% at 5 years. The recurrence rate in 78 of the 81 survivors who have been followed up for a mean of 18.8 months +/- 15.9 months (standard error) is 17.3% at 1 year and 11.1% at 2 and 3 years postoperatively. The presence of associated disease affects mortality: only one death in 34 patients with isolated coarctation; three deaths in 24 with coarctation plus ventricular septal defect; and 21 deaths in 45 infants with coarctation and complex lesions. Our present approach in the group with coarctation plus ventricular septal defect is to repair the coarctation without banding the pulmonary artery and then to close the defect if the infant remains in failure. Operative survival was 13 of 13 without pulmonary artery banding and 11 of 14 with pulmonary artery banding.

Age Factors↗

PubMed1984

Serous fluid leakage: a complication following the modified Blalock-Taussig shunt.

Polytetrafluoroethylene tubular grafts are useful in performing a systemic-to-pulmonary artery shunt (modified Blalock-Taussig). They allow a controlled-volume shunt, avoid kinking of the pulmonary artery, and preserve distal flow in the subclavian artery. Unfortunately, occasionally excessive serous fluid will drain through the interstices of the fabric. This results in excessive and prolonged chest tube drainage and/or localized seroma formation around the graft. This complication occurred in 26 children, an incidence of 18.8% of the 138 modified Blalock-Taussig operations. Repeat thoracotomy was required in four of these children--for evacuation of seroma mass in three and for relief of cardiac tamponade in one. Four other children required reinsertion of pleural or pericardial chest drains for excessive serous drainage persisting as long as 6 weeks after operation. Wrapping of the graft with silicone sheeting to facilitate subsequent takedown of the shunt led to seroma formation in five of nine children. We believe this practice should be abandoned. Excessive drainage of serous fluid through the interstices of PTFE grafts in almost 20% of our patients has compromised an otherwise satisfactory result of the modified Blalock-Taussig operation.

Blood Vessel Prosthesis↗

PubMed1983

The influence of high carbohydrate diet on plasma glucose and insulin of trained subjects.

In previous studies we have shown that when endurance athletes refrain from daily exercise for three days, they rapidly loose their enhanced insulin sensitivity. This finding suggests that a precompetitive high carbohydrate diet with reduced training might alter plasma glucose and insulin regulation. To test this hypothesis, six long distance runners were recruited to participate in a five-day experiment. During the first two days, the subjects fasted while running 16 km d-1. Thereafter, they consumed 16.3 MJ (3900 kcal) and 539 g carbohydrate per day for three days while remaining inactive. Before and after each portion of this experiment, an intravenous glucose tolerance test (IVGTT) was performed in fasting state. As expected, fasting with exercise induced a considerable deterioration of glucose tolerance, as reflected by lower K value and higher total area glucose during IVGTT. The high carbohydrate refeeding restored glucose tolerance to a level comparable to that observed when subjects maintain their usual life habits. However, while a decrease in insulin sensitivity is observed in subjects inactive for three days, the insulin sparing effect of exercise training is retained if this period of inactivity is preceded by two days of fast accompanied by exercise. These results show that glucose disposal and insulin response to glucose injection are not adversely modified by the precompetitive "glycogen loading" procedure.

Blood Glucose↗

PubMed1983

Diminished dietary thermogenesis in exercise-trained human subjects.

The influence of exercise-training on dietary-induced thermogenesis (DIT) was investigated in humans. The resting metabolic rate was identical in trained and non-trained subjects, but the response to a meal containing 1,636 kcal (6.9 MJ) was markedly lower in trained subjects. Mean dorsal skin temperature, as measured by thermography, was not influenced by training. A significant correlation was observed between postprandial RQ and DIT, which indicates that the reduced energy expenditure noted in trained subjects is related to a greater lipid oxidation. This sparing effect of exercise-training on energy utilization in the form of carbohydrate, is interpreted as adaptive in the sense that energy is preserved for the purpose of producing work.

Adult↗

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↗

PubMed1983

Pancreatic insulin response in relation to exercise training.

The present study was undertaken to measure the effects of exercise training on pancreatic insulin secretion in response to glucose and nonglucose stimuli. Wistar female rats with an initial body weight of approximately 180 g were divided into trained and sedentary groups. After a period of 10 weeks of training, glucose-, tolbutamide-, and arginine-tolerance tests were performed in vivo in both trained and untrained animals. The tests were done in nonanesthetized animals 40 h after the last exercise bout. It was found that exercise training leads to a diminution of plasma insulin levels after either glucose, tolbutamide, or arginine administration. These results present direct evidence that exercise training reduces plasma insulin response not only to glucose but also to nonglucidic secretagogues.

Animals↗

PubMed1983

A murine monoclonal antibody against blood group H type-1 and -2 structures.

A murine anti-H monoclonal antibody was produced. This antibody, called sp115, is an IgM that does not agglutinate classical Bombay. Sp115 may differentiate the two categories of H-deficient phenotypes. It detects H substance in both plasma and fresh saliva. Tissue antigen is found when using this antibody. The specificity of sp115 antibody was determined by adsorption with, and elution from synthetic oligosaccharide immunoadsorbents. Sp115 does not distinguish H type-1 and H type 2-structures.

ABO Blood-Group System↗

PubMed1982

Variations in plasma glucose, insulin, growth hormone and catecholamines in response to insulin in trained and non-trained subjects.

Previous studies have shown a reduced insulin secretion in trained subjects challenged by a glucose load. In the present study the response to insulin of 8 athletes was compared to that of 8 non-trained subjects. The disappearance of plasma insulin was not different between the two groups, but the level of hypoglycemia was greater in the trained subjects. The injection of insulin increased the plasma levels of epinephrine (E) and norepinephrine (NE) in both groups of subjects, but the raise in E was greater in the trained subjects. Similarly, the increase of growth hormone (GH) was greater in the trained subjects. These findings substantiate previous results showing a decreased insulinic index and an increased insulin binding to monocytes in trained subjects. It is also suggested that the enhanced E and GH secretion found in trained subjects injected with insulin, is possibly related to the greater fall in plasma glucose in the trained subjects compared to the non-trained subjects.

Adult↗

PubMed1982

Role of exercise-training in the prevention of hyperinsulinemia caused by high energy diet.

The present study was undertaken to determine whether exercise-training done in combination with feeding a high energy diet could modulate carbohydrate metabolism. Male rats were divided into exercise-trained or sedentary groups that received either a palatable high energy diet or merely standard laboratory diet. After 10 weeks of training, the animals were subjected to an intravenous glucose tolerance test. Body weight, epididymal fat pads, and adipocyte volume were reduced following training. The results also showed that exercise-training protects against deterioration of glucose tolerance produced by high energy diet. Training prevented the elevation of basal as well as glucose challenged insulin levels induced by the high energy diet in spite of a high fat as well as high overall energy intake. A highly significant coefficient of correlation (r = 0.78, P less than 0.01) was observed between the size of adipocytes and the insulin response to glucose load and suggests that the prevention of hyperinsulinemia in rats fed high energy foods while training could be associated with the ability to prevent obesity.

Adipose Tissue↗

PubMed1982

Catecholamines and triiodothyronine variations and the calorigenic response to norepinephrine in cold-adapted and exercise-trained rats.

A comparison was made of the thermogenic response to norepinephrine (NE) in cold-adapted (2 h per day at -15 degrees C for 5 weeks) and in exercise-trained rats (2 h swimming per day for 5 weeks). The oxygen consumption and the plasma catecholamine elevation were comparable for both conditions. Similarly plasma corticosterone determinations indicated comparable elevations in acute stress exposure and reduced responses in both exercise-trained and cold-adapted rats. The marked increase in colonic temperature which was observed in cold-adapted animals injected with NE (30 micrograms/100 g s.c.) was not found in exercise-trained rats. Similarly the brown adipose tissue was double in size in the cold-adapted rats but remained unchanged with exercise training. An important elevation of triiodothyronine (T3) was found in cold-exposed rats, either adapted or not. However, exercise was found to decrease plasma T3 in trained and nontrained rats. The results indicate that swimming for 2 h and exposure to cold (-15 degrees C) for 2 h produced comparable elevation of plasma corticosterone and catecholamine, and of oxygen consumption. However, only the cold-adapted animals develop a NE-induced thermogenesis. It is suggested that thyroid hormones are necessary as permissive factor, in stress-induced thermogenesis.

Acclimatization↗

PubMed1982

Interactions between dietary obesity and exercise-training on carbohydrate metabolism.

The present study addressed the important question of whether exercise-training could reduce insulin levels in exercise-trained rats made obese by a diet composed of palatable foods. Female rats were divided in exercise-trained or in sedentary groups which receive either a palatable high-energy diet or merely a standard laboratory chow. The high-energy diet was composed of supermarket foods including chocolate chips cookies, pop-corn, bologna, etc. Exercise-training program consisted of forced swimming, 6 d per week, 2 h per d, in water maintained at 36 degrees C. At the end of both fattening and exercise-training program, the animals were subjected to an intravenous glucose tolerance test. The results showed that high-energy diet and exercise-training had opposite effects on both glucose tolerance and insulin secretion: the former impaired glucose tolerance and increased insulin levels, whereas the latter leads to opposite adaptations. In addition, some abnormalities in insulin metabolism persisted in rats simultaneously assigned to exercise-training and high-energy diet. Thus, the present results also suggested that physical training alone could not reduce plasma insulin under control levels, and that a change in energy balance is possibly necessary to achieve this purpose.

Adipose Tissue↗

PubMed1982

In vitro studies of amphibian gastrula cells.

Experiments are presented to determine whether Rana pipiens gastrula cells differentiate in vitro as they do in vivo with respect to rate, morphology and spreading characteristics. Comparisons are made between presumptive germ layer cells isolated at late blastula, cultured for 24 h, and the same cell types form late gastrula cultured for 1 h (LeBlanc and Brick, 1981a). These cells are chronologically similar and should be morphologically similar at the end of their respective culture periods if in vivo and in vitro differentiation are proceeding in the same direction and rate. Five hour cultures of the same cell types were compared to 1 h cultures in media with enhanced Ca2+ (LeBlanc and Brick, 1981b) to study the role of Ca2+ as a modulator of spreading and production of cell protrusions, and the rate at which these occur, as these relate to morphogenetic movements. The data and inferences can be summarized as follows: (1) Some Rana pipiens late blastula and gastrula cells appear to differentiate morphologically in vitro similarly to their differentiation in vivo. (2) In vitro differentiation is autonomous indicating that determination occurred prior to late blastula, mid-gastrula or late gastrula depending on when cells were isolated. (3) The presence of two sub-populations is some germ layer cell isolate indicates determinative interactions had occurred prior to isolation. (4) Morphologic similarity of cells in standard culture for 5 h to the same cells in culture with additional Ca2+ for 1 h suggests that Ca2+ modulates spreading and projection formation and the rate at which these occur. (5) The upper cell surface of these cells may provide adhesive sites for plasmalemma projections from adjacent cells.

Animals↗

PubMed1982

[Effects of cold wind on the response to muscular exercise].

The purpose of the present studies was to determine if the response to exercise is modified by a cold wind. When the subjects exercised in the cold (with or without wind), cheek and forehead temperatures were higher, but the temperature of the nose was lower than in the resting state. The decrease in heart rate, normally observed when cold wind is blown on the face at rest, persisted and even became greater during exercise up to a heart rate of 150 beats/minute. However, this decrease was progressively eliminated as heart rate increased further up to maximum. These results have shown that a cold wind can diminish the heart rate response to submaximal exercise in comparison with a no wind condition (delta up to 20 beats/minute at a heart rate of 150 beats/minute).

Adult↗

PubMed1981

Norepinephrine mobilization of free fatty acids in endurance trained rats.

Wistar rats were trained to run, a male group on 6 days a week for 4 months at 28 m x min-1, and a female group on 5 days a week for 5-6 months at 31 m x min-1. Male rats were given continuous infusion of [1-14C] palmitate-albumin tracer via a jugular catheter at a constant infusion rate of 80 nCI x min-1. The effect of concurrent norepinephrine (NE) infusion on free fatty acid (FFA) mobilization was then studied in this group. NE increased plasma FFA levels similarly in both control and endurance trained male groups. Turnover of FFA, however, increased in response to NE relatively less in the trained group. Furthermore, NE caused the metabolic clearance rate of FFA (MCR) to decrease in control animals but not in runners. Colonic temperature was slightly increased by NE infusion in the control group only. Female rats were given a bolus injection of 5 microCi of [1-14C] palmitate-rat serum through a venous cannula. The disappearance of radioactivity in the circulation was measured. MCR values were higher in the trained group (p = 0.01). The effect of NE infusion on FFA levels was also studied in female animals. NE caused levels to increase in both control and trained rats. FFA concentrations were however more elevated in the control than in the trained group, before and during NE infusion. The relative increase tended to be less extensive in the trained group (p = 0.06). It is concluded that long term endurance training diminishes calorigenic and fat mobilizing actions of NE in the rat in vivo.

Animals↗