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Biomedical subjects

A Tremblay

Publications and source records attributed to A Tremblay.

At least 289 records · Page 16Linked to original sources
PubMed1988

Relationships between body fatness, adipose tissue distribution and blood pressure in men and women.

The relationships between body fatness, fat distribution and blood pressure (BP) were studied in 234 women and 238 men, aged 18-50 years. In both sexes, subcutaneous (s.c.) fat (assessed by the measurement of s.c. skinfolds) and percent body fat (measured by underwater weighing) were correlated significantly with diastolic (0.27 less than or equal to r less than or equal to 0.37, p less than 0.0005) and systolic (0.17 less than or equal to r less than or equal to 0.29, p less than 0.01) BP. In either sex, the proportion of s.c. trunk fat as reflected by the ratio of trunk/extremity skinfolds showed significant associations with diastolic (men: r = 0.35, women: r = 0.20, p less than 0.01) and systolic BP (men: r = 0.15, women: r = 0.17, p less than 0.05). Control for the effects of covariables potentially affecting BP (energy intake, energy expenditure, maximal oxygen consumption, cigarette smoking, alcohol intake and age) revealed significant effects of age and alcohol intake on BP in men. In women, only age appeared to be associated with BP variation. Partial correlations after control for age and alcohol intake indicated a significant association between the trunk/extremity skinfolds ratio and diastolic BP in men. Such a correlation was not found in women after control for the effect of age. Analysis of variance (2 x 2 factorial with fixed effects) confirmed that, in men, the distribution of s.c. body fat was, per se, associated with diastolic BP (F = 8.43, p less than 0.01), whereas the proportional of s.c. trunk fat was not related to systolic BP in both sexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1988

Familial resemblance in energy intake: contribution of genetic and environmental factors.

Total energy intake and intakes of carbohydrate, fat, and protein as well as the percentage of energy derived from these nutrients were calculated from a 3-d dietary record in 1597 subjects living in 375 families of French descent. Familial correlations were computed in pairs of biological relatives and relatives by adoption and used in the path-analysis BETA model to determine the contribution of genetic and nongenetic factors in the familial resemblance observed in energy intake. No significant genetic effect was found for intake of any nutrient tested (h2 less than or equal to 11%) and cultural inheritance was found to be more important than genetic inheritance. Nontransmitted environmental factors, including home environmental effects, were found to account for more than 50% of the variation observed in the energy-intake components. These results suggest that the average genetic influence on nutrient intake is negligible and that nongenetic effects associated mainly with home environmental effects are the major affecters of energy intake.

Adolescent↗
PubMed1988

Physical training and changes in regional adipose tissue distribution.

Obesity has been associated with numerous metabolic complications, such as changes in the concentration and/or composition of plasma lipoproteins, glucose intolerance and hyperinsulinemia leading to diabetes and hypertension. The relation of obesity to cardiovascular disease has not, however, been consistently reported. Recent prospective studies have clearly indicated that the distribution of adipose tissue was a significant cardiovascular risk factor and numerous studies have shown that metabolic disturbances were more closely associated with the level of abdominal fat than excess adiposity per se. As obese men generally store their energy excess in the abdominal region and women in the peripheral fat depots, the metabolic complications of obesity seem to be more closely related to adiposity in men than in women. It is suggested that the sex dimorphism observed in adipose tissue localization could partly explain the greater cardiovascular risk associated with obesity in men than in women. Indeed, obese women with a "male" (abdominal) distribution of body fat have greater metabolic complications than women with lower body fat. When aerobic exercise-training is used to induce weight loss, men generally lose more fat than women. In men, the loss of adipose tissue appears to be central, potentially reducing the risk of cardiovascular disease, whereas a relative resistance to fat loss is observed in women compared to men. Although resistance to fat loss is noted in women, those with a "male" distribution of adipose tissue (high waist-to-hip ratio and high intra-abdominal fat deposition) and with associated metabolic complications greatly benefit from aerobic exercise-training.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1988

Abdominal adipose tissue and serum HDL-cholesterol: association independent from obesity and serum triglyceride concentration.

It has been recently shown that an excess of abdominal fat was associated with reduced serum HDL-cholesterol level, supporting previous studies that have reported a relationship between fat distribution and cardiovascular risk factors. Since a negative relationship has been observed between serum triglyceride and HDL-cholesterol concentrations, the associations between body fat distribution and HDL-cholesterol level was studied with control over serum triglycerides in a sample of 429 healthy adult men. The relative distribution of subcutaneous fat, as reflected by the trunk to extremity skinfolds (T/E) ratio and the absolute amount of subcutaneous abdominal fat, obtained by the measurement of the abdominal skinfold thickness, were significantly correlated with serum triglycerides (r = 0.27 and 0.35 respectively, P less than 0.0001), with serum HDL-cholesterol (r = -0.14, P less than 0.01, and -0.26, P less than 0.0001) and with the serum HDL-cholesterol/total cholesterol ratio (r = -0.25 and -0.39, P less than 0.0001). Analysis of variance on two factors, the T/E ratio and the body mass index (BMI), revealed significant and independent effects of adiposity and relative distribution of subcutaneous fat on serum lipids and HDL-cholesterol (0.05 greater than P less than 0.001). However, when comparable analyses of variance were performed to study the respective contributions of obesity (as measured by the BMI) and the absolute amount of abdominal fat (as measured by the abdominal skinfold), most of the variance in serum triglycerides, cholesterol and HDL-cholesterol was explained by abdominal fat alone and not by the BMI. Therefore, it appeared that with the exception of the HDL-cholesterol/total cholesterol ratio, the association between obesity and serum lipids and HDL-cholesterol was, in the present sample, primarily explained by the amount of abdominal fat. As reported by others, serum triglyceride level was negatively correlated with HDL-cholesterol (r = -0.33, P less than 0.0001) and the HDL-cholesterol/total cholesterol ratio (r = -0.54, P less than 0.0001). After cholesterol and HDL-cholesterol scores were adjusted for the effect of triglycerides, the T/E ratio was no longer associated with serum HDL-cholesterol whereas the abdominal skinfold remained significantly correlated with serum HDL-cholesterol concentration (r = -0.16, P less than 0.01). These results suggest that a portion of the association between body fat topography and serum HDL-cholesterol is mediated by the effect of fat distribution on serum triglycerides.(ABSTRACT TRUNCATED AT 400 WORDS)

Abdominal Muscles↗
PubMed1988

Sensitivity to overfeeding: the Quebec experiment with identical twins.

The role of the genotype in the response to short-term overfeeding was assessed by submitted six pairs of male monozygotic twins to a 4.2 MJ (1000 kcal) per day energy intake surplus for a period of 22 consecutive days. Individual differences in fat mass and fat-free mass gains were observed in response to overfeeding but they were not randomly distributed. Indeed, the within-pair resemblance in the response was striking when compared to the heterogeneity found among the pairs in adiposity and fat-free mass gains. The intrapair resemblance in the response to overfeeding as assessed by the intraclass coefficient computed with the individual changes, reached 0.88 for total fat mass and 0.76 for fat-free mass. A similar trend for a genetically determined pattern of adaptation to overfeeding was observed for resting metabolic rate (intraclass = 0.63), thermic effect of a meal (intraclass = 0.62), and energy cost of submaximal exercise (intraclass = 0.78) when the data were analysed in terms of changes in oxygen uptake. On the other hand, no major alterations in glucose and insulin response to a glucose load or a test meal, in cardio-pulmonary adaptation to submaximal exercise and in maximal exercise tolerance were found with overfeeding. In contrast, the response of suprailiac fat cell lipolysis (intraclass of about 0.7) and heparin releasable adipose tissue lipoprotein lipase (intraclass - 0.82) varied among individuals but was highly homogeneous within genotypes. Similarly, a genotype-overfeeding interaction effect was seen for serum triglycerides (intraclass = 0.69), HDL-cholesterol (intraclass = 0.85), and the HDL-cholesterol to total cholesterol ratio (intraclass = 0.82). Multiple correlation analyses suggest that much of the variance in the response of fat mass (R = 0.65) and fat-free mass (R = 0.81) is accounted for by alterations in the energy expenditure components assessed in the study. If one takes into account the measurement errors always present in such complex studies and the fact that only a limited fraction of the energy expenditure of activity was considered by design, one can conclude that the genotype determines to a large extent the response variation to short-term overfeeding. In particular, the genotype-overfeeding interaction effect for body composition changes seems to be mediated by the various energy expenditure components, themselves characterized by significant genotype-overfeeding interaction effects.(ABSTRACT TRUNCATED AT 400 WORDS)

Adipose Tissue↗
PubMed1988

Effect of a three-day interruption of exercise-training on resting metabolic rate and glucose-induced thermogenesis in training individuals.

Exercise-training has been shown to influence resting components of energy expenditure in lean and obese individuals. Moreover, experimental data suggest that the effect of training on these components could represent an acute effect of exercise. In this regard, the present study was undertaken to determine whether resting metabolic rate (RMR) and glucose-induced thermogenesis (GIT) could be modified depending on the delay elapsing between the last exercise session of a training program and calorimetric measurements. Eight trained individuals were tested 16 h after a 90-min exercise bout and following a 3-day interruption of training. A significant decrease in RMR (-6.6 percent, P less than 0.05) was observed in response to exercise cessation. On the other hand, an increased GIT was noted following the 3-day rest period and this effect was also statistically significant. These results show that short-term interruption of training can affect substantially RMR and GIT in trained individuals, indicating that the time elapsing since the last exercise session must be taken into account in the interpretation of the effects of physical training on both these parameters.

Basal Metabolism↗
PubMed1988

Inheritance of the amount and distribution of human body fat.

Despite recent advances, controversy continues about the inheritance of the amount and distribution of body fat. We have studied the genetic and 'cultural' (nongenetic) transmission between generations of the body mass index, sum of six skinfold measurements, percentage of body fat, fat mass, fat-free mass, and two indicators of fat distribution. These data were obtained in 1698 members of 409 families, which included the following pairs of family members: spouses, (maximum number of pairs = 348), foster parent-adopted child (322), siblings by adoption (120), first-degree cousins (95), uncle/aunt-nephew/niece (88), parent-natural child (1239), full sibs (370), dizygotic twins (69), and monozygotic twins (87). The total transmissible variance ranged from about 40 percent for the amount of subcutaneous fat to 60 percent for the pattern of subcutaneous fat distribution. Biological inheritance accounted for only 5 percent of the variance for subcutaneous fat and the body mass index, but 20 to 30 percent for the percentage of body fat, fat mass, fat-free mass, and fat distribution. These data suggest that the amount of internal fat is influenced by heredity more than the amount of subcutaneous fat. Furthermore, we consistently found that nongenetic influences are quite important in determining the amount and distribution of body fat in the population. These estimates may differ in the subpopulation of obese individuals.

Adipose Tissue↗
PubMed1987

Heredity and changes in body composition and adipose tissue metabolism after short-term exercise-training.

The purpose of the experiment was to investigate the genotype dependency of body composition and adipose tissue metabolism following short-term exercise-training. Six pairs of male, sedentary monozygotic twins took part in a 22 day ergocycle training program at 58% VO2max, with a mean exercise duration of 116 min x day-1. Body weight, fat mass, percent body fat and VO2max, were evaluated before and after the training program. From a suprailiac region fat biopsy, the following adipose tissue metabolic variables were evaluated: fat cell diameter, basal and epinephrine stimulated lipolysis, basal and insulin stimulated lipogenesis from glucose and heparin releasable lipoprotein lipase activity. The exercise-training program increased (p less than 0.01) VO2max and decreased (p less than 0.01) body weight, fat mass and percent body fat. Variation in response within twin pairs was not significantly different than response between pairs in the aforementioned variables. However, a significant within pair resemblance (p less than 0.01) for changes in fat free mass was observed. Adipose tissue metabolic indicators exhibited a large interindividual variation in response to exercise-training. Significant within twin pair resemblance was observed only for basal lipogenesis. Moreover, the non significant within twin pair resemblance for changes in body fat and adipose tissue metabolic indicators suggests that heredity is not a major factor influencing changes in body fat and adipose tissue indicators to short-term training resulting in negative energy balance. Changes in fat free mass were, however, closely coupled to the genotype.

Adipose Tissue↗
PubMed1987

Acute effects of endurance exercise on human adipose tissue metabolism.

In order to study the acute effects of exercise on adipose tissue metabolism, 27 sedentary male subjects, 18 to 27 years of age, performed a prolonged aerobic exercise test. Biopsies of adipose tissue were obtained from the suprailiac fat depot before and immediately after a 90-minute period of exercise on ergocycle at an average intensity of 88% of maximal heart rate. Fat cells, isolated by collagenase digestion, were measured for their glucose conversion into triglycerides and for lipolytic activity. Adipose tissue lipoprotein lipase activity released by heparin was also determined. Mean basal and insulin-stimulated glucose conversion into triglycerides decreased significantly with exercise (P less than .05) while adipose tissue lipoprotein lipase activity increased (P less than .01). Fat cell lipolysis increased during exercise only for its epinephrine-stimulated values (P less than .05). The total amount of work performed during the test was correlated only with changes in lipoprotein lipase activity (r = .42, P less than .05). Finally, the changes induced by exercise in lipoprotein lipase activity (r = .37, P less than .05) and insulin-stimulated glucose conversion into triglycerides (r = .61, P less than .01) were positively correlated with fat cell weight. These results indicate that adipose tissue metabolic activities are selectively influenced by endurance exercise. They also suggest that these metabolic changes are not closely coupled with the amount of work performed in a prolonged exercise bout.

Adipose Tissue↗
PubMed1987

Genotype-influenced changes in serum HDL cholesterol after short-term overfeeding in man: association with plasma insulin and triglyceride levels.

Six pairs of male monozygotic (MZ) twins were submitted to a 22-day overfeeding period during which they ingested a daily surplus of 1,000 kcal above their individual daily energy needs in the form of a mixed diet. Serum lipids, lipoproteins, and apoprotein A and B concentrations were measured before and after the overfeeding period. Percentage of body fat, fasting plasma glucose, and insulin levels as well as plasma glucose and insulin concentrations after a glucose challenge were also measured before and after overfeeding. Results showed that before overfeeding, MZ twins exhibited a significant intrapair resemblance for total serum cholesterol (CHOL), triglycerides (TG), low density lipoprotein cholesterol (LDL-C), and for the high density lipoprotein-cholesterol/total cholesterol ratio (HDL-C/CHOL) (8.2 less than or equal to F ratios less than or equal to 32.7, P less than .01). The overfeeding experiment induced significant increases only in serum CHOL (P less than .01) and in serum LDL-C (P less than .05). However, although mean group values of serum TG, HDL-C, and HDL-C/CHOL ratio were not significantly modified by overfeeding, there were large interindividual variations in the response of these variables to the experiment. Results suggest that changes in serum TG, HDL-C, and in the HDL-C/CHOL ratio were significantly associated with the genotype of the subjects as a significant intrapair resemblance in the response to overfeeding was observed for these variables (0.69 less than or equal to r less than or equal to .85, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Apolipoproteins A↗
PubMed1987

Familial aggregation in physical fitness, coronary heart disease risk factors, and pulmonary function measurements.

In order to test for the presence of familial aggregation in physical fitness and coronary heart disease risk factors, body fat, submaximal power output, muscular strength, muscular endurance, blood pressure, pulmonary functions, and several blood biochemical variables were measured in 304 nuclear families living in the Quebec city area. Analysis of variance indicated a larger between-family than within-family variation for all the variables. When all members of nuclear families were considered, intraclass correlations ranged from 0.21 to 0.34 (P less than or equal to 0.01). Interclass correlations computed for various pairs of relatives revealed significant parent-child and sibling correlations for all the variables (0.14 less than or equal to r less than or equal to 0.55; P less than or equal to 0.01). On the other hand, spousal correlations tended to be lower but significant (0.10 less than or equal to r less than or equal to 0.30; P less than or equal to 0.05) for all variables except subcutaneous fat and hemoglobin concentration. These results suggest that heredity and common lifestyle shared by members of nuclear families are responsible for the familial aggregation of physical fitness, coronary heart disease risk factors, and pulmonary functions. The findings also support the notion of considering the nuclear family as a unit of intervention in the application of preventive measures aimed at the reduction of several risk factors.

Adolescent↗
PubMed1987

Is the response of plasma glucose and insulin to short-term exercise-training genetically determined?

Six male monozygotic (MZ) twin pairs participated in the present study which was undertaken to assess the contribution of heredity to changes in plasma glucose and insulin in response to exercise-training. This group was submitted to a vigorous ergocycle exercise program inducing a surplus in energy expenditure of 1000 kcal/day over habitual energy expenditure during 22 consecutive days. An oral glucose tolerance test (OGTT, 75 g glucose) was performed before and about 16 hours after the experimental period. Fasting plasma glucose as well as its increase over basal level (delta area) during OGTT were not modified by exercise-training (p greater than 0.05), although a marked reduction in insulin was observed, both in the fasting state and during the OGTT (p less than 0.01). To assess the extent to which heredity influenced the response to the treatment, i.e. the genotype-training interaction, within and between MZ twin pairs means of squares were calculated. A significant intrapair resemblance in the response to exercise-training was observed for fasting insulin and delta insulin area/delta glucose area ratio during OGTT, but not for delta insulin area. These results provide some indications about a possible role of the genotype on the sensitivity to reduce plasma insulin in response to exercise-training. However, this hypothesis needs to be substantiated by other experimental data with control over the genotype of subjects.

Adolescent↗
PubMed1987

Heredity and overfeeding-induced changes in submaximal exercise VO2.

The present study investigated the role of heredity in determining changes in the energy cost of submaximal exercise in response to short-term overfeeding. Six pairs of monozygotic twins were subjected to a 1,000 kcal/day surplus for 22 days with careful experimental controls over food intake and physical activities. O2 consumption (VO2) was measured during a submaximal treadmill exercise test 165 min postprandially before and the morning after the overfeeding protocol. As expected, overfeeding induced significant increases in body weight and fat mass. No significant increase in mean exercise VO2 was observed after overfeeding. However, the interindividual variation in overfeeding-induced changes in exercise VO2 was large and not randomly distributed. When comparing intrapair variance for changes in exercise VO2 to interpair variance, a moderate to high within-pair resemblance in response, i.e., a genotype-overfeeding interaction, was observed. Changes in exercise VO2 were positively correlated with those in postexercise levels of blood catecholamines, particularly epinephrine. A negative correlation was found between changes in exercise VO2 and body fat gain. These results are consistent with the concept of a role for the sympathoadrenal system in the regulation of adaptive thermogenesis and the predisposition to store fat. Moreover, these data suggest that the sensitivity to adapt in exercise energy expenditure after overfeeding is inherited to a significant extent.

Adult↗