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Biomedical subjects

C Leblanc

Publications and source records attributed to C Leblanc.

64 records · Page 4Linked to original sources
PubMed1976

Relationships between skeletal maturity and submaximal working capacity in boys 8 to 18 years.

Skeletal age (SA) height, weight, PWC130, Vo2 at 130 heart rate (Vo130) and cardiorespiratory adaptation to work at 3 kgm-sec-1 were measured in 237 boys ranging in age from 8 to 18 years. Correlations for the total population for the variables of the study are generally higher with SA than with chronological age (CA), although there is no significant difference between the two sets of correlations. Analysis of linear trend indicate that significant nonlinear components are more frequent in the relationships between the variables and SA than with CA.Multiple regression analyses for each variate as dependent variable indicate that height and body weight generally contribute more to the explained variance, while SA is the next best predictor. CA is the least significant of the four independent variables. The total variance explained between any of the submaximal working capacity related measures acting as dependent variable and CA, height and weight is not significantly affected by the presence or absence of SA. The present study thus indicates that SA is not a significant factor in explaining submaximal working capacity, beyond CA, height and weight, when considered over the 8 to 18 year age span. However, when considering shorter age spans, or when considering the adolescent period (12-16 years), SA correlates better with PWC130 (.320 less than r less than .675) and with Vo130 (.299 less than r less than .772).

Adolescent↗
PubMed1975

Ultrastructural localization of in vivo-bound complement in bullous pemphigoid.

Antihuman complement component C3 labeled with horseradish peroxidase was used to reveal the ultrastructural localization of complement in two cases of bullous pemphigoid. The complement deposits were shown to be exclusively located in the space between the plasma membrane of the basal cells and the basal lamina. This corresponds exactly to the ultrastructural localization of immunoglobulins in bullous pemphigoid.

Biopsy↗
PubMedDate not supplied

Familial resemblance in fatness indicators.

Family resemblance in fatness has been studied in 481 individuals from 114 families of French descent living in the greater Quebec city area. Subjects were measured for the following fatness indicators: triceps, biceps, subscapular, suprailiac, abdominal and medial calf skinfolds. The sum of these six skinfolds as well as a prediction of percent body fat (Durnin and Rahaman 1967) were also considered. Data were standardized for appropriate age and sex classes yielding SS scores. The influence of relevant lifestyle variables (energy intake, energy expenditure and socioeconomic status) were statistically removed from SS yeilding residual scores (RS) that were then submitted to familial analyses. Analyses of variance indicate that there is a larger between family variation than within (P less than or equal to 0.01) for SS when considering either the whole nuclear family or sibships; in these instances, the intra-class correlation ranges from 0.15 to 0.26. There was, however, no significant resemblance among spouses for the SS fatness indicators. Similar values were essentially found for RS fatness indicators. Furthermore, husband-wife inter-class correlations were not significant with the exception of subscapular and calf skinfold RS. Covariations between biological relatives are however significant (0.16 less than or equal to r less than or equal to 0.24, P less than or equal to 0.01) for SS and remain essentially unchanged after statistical control over the lifestyle variables (0.16 less than or equal to r less than or equal to 0.40, P less than or equal to 0.01). The findings that spouses do not covary significantly in fatness, while biological relatives of traditional nuclear families exhibit a significant degree of resemblance even after statistical control over daily energy intake, daily energy expenditure and socioeconomic status provide evidence supporting the hypothesis that there is a substantial genetic effect in human fatness.

Adolescent↗
PubMedDate not supplied

Submaximal power output in adopted and biological siblings.

Submaximal power output was determined in relative steady state on a bicycle ergometer at a heart rate of 150 beats per minute (PWC150). PWC150 was measured in 880 individuals, 9 to 26 years of age, belonging to 46 sibships of adopted sibs, 66 sibships of unrelated individuals including adoptees, 33 sibships of first-degree cousins, 225 sibships of biological sibs, 56 sibships of DZ twins and 54 sibships of MZ twins. PWC150, PWC150/kg of body weight, PWC150/kg lean body mass, PWC150/cm of height and PWC150/m2 of body surface area were submitted to analysis of variance and correlation analysis after statistical control over age and sex of subjects. Few significant resemblances were found in PWC measurements for adoptive siblings, unrelated sibs and cousins. Sibling resemblance was, however, significant for the sibships of biological sibs, and of DZ and MZ twins. Interclass correlations reached significance only in pairs of biological brothers and sisters, and in pairs of DZ and MZ twins. Estimates of total genetic effect in PWC150/kg in a population of free-living children, adolescents and young adults vary from 0.30 to 0.48. It is concluded that submaximal power output is only moderately affected by the genotype.

Adolescent↗
PubMedDate not supplied

Genetic and environmental sources of variation in physical fitness.

The technique of path analysis was used to assess inherited and environmental variance components in physical fitness indicators measured in 1630 subjects from 375 families of French descent living in the greater Québec city area. For that purpose, submaximal power output (PWC150/kg), muscular endurance, muscular strength, reaction time and movement time were evaluated during a visit of the family to the laboratory. Inter-class correlations in various types of relatives were computed from scores adjusted for linear and non-linear effects of age and sex by a regression procedure (Y = age + sex + (age X sex) + age2). Correlations were then used in the path analytic BETA model which allows the partition of transmissible variance (t2) into genetic (h2) and cultural (b2) components. Results indicated that t2 accounted for 18% (movement time) to 63% (muscular strength) of the phenotypic variance. The contribution of genetic factors was found to be negligible for PWC150/kg and movement time, and accounted for about 20% of the phenotypic variance for reaction time and muscular endurance and 30% for muscular strength, while non-transmissible variance (1 - t2) accounted for 37% (muscular strength) to 82% (movement time) of the phenotypic variance. These results suggest that biological variation observed in the physical fitness level of a healthy population is mainly associated with non-transmissible environment factors and that the contribution of heredity is moderate and clearly lower than previously reported.

Adolescent↗
PubMedDate not supplied

Genetic and environmental determinants of serum lipids and lipoproteins in French Canadian families.

The contribution of genetic and environmental factors in serum triglycerides (TG), total cholesterol (CHOL), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), and HDL-C/CHOL ratio were studied in 1630 subjects from 375 families of French descent by using a path analysis procedure. Familial correlations were computed in several pairs of biological relatives and relatives by adoption after adjustment for age and gender effects and after further adjustment for physical fitness, level of habitual physical activity, total body fat and fat distribution, diet, smoking, and alcohol consumption. The model of path analysis allowed the separation of transmissible variance (t2) into genetic (h2) and cultural (b2) components of inheritance. Under the most parsimonious solution and after adjustment for age, gender, and concomitants, the transmissible variance was entirely accounted for by genetic factors (t2 = h2), with h2 estimates of 0.52, 0.55, 0.60, and 0.63 for TG, CHOL, LDL-C, HDL-C, and HDL-C/CHOL, respectively. These estimates were similar to those obtained after adjustment for age and gender effects only. The contribution of nontransmissible environmental factors ranged from 0.48 for TG to 0.37 for HDL-C/CHOL ratio. These results suggest that both genetic and environmental factors contribute to the variation in blood lipids and lipoproteins in this population and that nongenetic influences are not associated with cultural factors transmitted across generations.

Adolescent↗