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Biomedical subjects

C Leblanc

Publications and source records attributed to C Leblanc.

At least 37 records · Page 2Linked to original sources
PubMed1994

Allergenic exposure, IgE-mediated sensitization, and related symptoms in lawn cutters.

AIMS: The aims of the study conducted on lawn cutters were: (1) to evaluate exposure to pollens and molds; and (2) to assess the prevalence rate of IgE sensitization and symptoms in relation to exposure to pollens and molds. METHODS: Environmental assessment was done with the use of personal samplers on eight workers. Our population consisted of 181 municipal park workers, including 128 lawn cutters and 67 control subjects (blue-collar workers in the hospital). A questionnaire was administered, as well as skin prick tests with seven common inhalants including pollens and eight grass molds. The main outcome variables were grass or mold sensitization (at least one of eight molds) and work-related rhinitis, conjunctivitis, and rhinoconjunctivitis. Atopy and exposure to park-related allergens, as well as sensitization to grass pollens, were considered as explanatory factors. Smoking was taken into consideration as a covariant. Both presence and duration of occupational exposure to park-related allergens were considered as parameters of exposure. Duration of exposure (months x years of exposure as lawn cutters) was used as a continuous or as a categorical variable. RESULTS: Environmental monitoring showed that the concentration of pollens and molds decreased in magnitude from samples collected close to lawn cutters faces, short distance away in parks, and in the general environment. There was no difference in the prevalence rates for atopy between lawn cutters (32%) and control subjects (37%). Sensitization rates to grass pollen were also similar in lawn cutters (18%) and in control subjects (22%). However, there was a tendency for prevalence rates of sensitization to molds to be greater among lawn cutters (12% to Alternaria) compared with control subjects (5%). In the logistic model atopy was significantly related to grass sensitization (odds ratio [OR] = 7.2), mold sensitization (OR = 9.3), and sensitization to Alternaria (OR = 5.8). Grass sensitization was a significant risk factor for park-related rhinitis (OR = 5.8), conjunctivitis (OR = 5.0), and rhinoconjunctivitis (OR = 9.4). Exposure for 12 years or more was associated with rhinoconjunctivitis with an OR of 4.1 (95% confidence interval, 1.0-16.7). Smoking was not significantly related to any outcome. CONCLUSION: We conclude that among lawn cutters exposure to pollens and molds is higher than in the general population, atopy is the main determinant of sensitization to these aeroallergens, and sensitization and, to a much lesser extent, exposure to grass are determinants of symptoms.

Adult↗
PubMed1994

Airway inflammation after removal from the causal agent in occupational asthma due to high and low molecular weight agents.

In order to determine 1) the features of airway inflammation after removal from exposure to high (HMW) and low (LMW) molecular weight agents 2) if there are any differences in the pattern of inflammation induced by these two types of agents, we studied 18 subjects with a recently confirmed diagnosis of occupational asthma (OA) due to HMW (n = 11) and LMW (n = 7) agents. The duration of asthma symptoms varied from 2 to 108 months (mean 33 months), and withdrawal from exposure to the sensitizing agent from 3 to 24 weeks (mean 10 weeks). All subjects underwent measurements of expiratory flow rates, methacholine inhalation tests, and a flexible bronchoscopy with bronchoalveolar lavage (BAL) and bronchial biopsies. Endoscopic findings were compared with a group of 10 normal subjects. At the time of the bronchoscopy, asthma symptoms were minimal in most subjects. Although 15/18 subjects had normal forced expiratory volume in one second (FEV1 > 80% pred), all subjects had increased airway responsiveness to methacholine (provocation concentration producing a 20% fall in FEV1 = 0.2-10.0 mg.ml-1). BAL analysis showed similar median percentages of the total number of cells and differentials in control subjects and those exposed to HMW and LMW agents. Bronchial biopsies showed that mean inflammatory cell count, both epithelial and sub-epithelial, was similarly raised in OA subjects exposed to either HMW or LMW agents, compared to controls, except for epithelial lymphocyte count. In contrast to the controls, bronchial biopsy of both groups with OA also showed other changes such as extensive epithelial desquamation, ciliary abnormalities of the epithelial cells, smooth muscle hyperplasia and subepithelial fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Exposure to domestic animals and risk of immunologic sensitization in subjects with asthma.

BACKGROUND: The objective of the study was to determine whether exposure to domestic animals plays a significant role, beyond atopy, in the development of immediate sensitization to animal-derived antigens. METHODS: To test this hypothesis, 200 subjects with asthma (85 male subjects and 115 female subjects; mean age, 37 +/- 16 years) seen consecutively in an asthma clinic were enrolled in a cross-sectional survey. Each subject answered a questionnaire about allergy symptoms and past and current exposure to domestic animals. Skin prick testing with extracts of common inhalant allergens including antigens from eight species of animal (cat, dog, horse, rabbit, rat, mouse, guinea pig, and hamster) were also carried out. RESULTS: Seventy-nine percent of subjects were atopic, and 91% had kept animals at home at some point (figures were 80% for dogs, 68% for cats, 23% for rabbits, and 20% for rodents). Using two-by-two tables, we showed that skin reactivity to at least one animal antigen was strongly linked to atopy (86% of atopic subjects had skin reactions as compared with 34% of nonatopic subjects: p < 0.001) but not to previous and current exposure to domestic animals (78% of both exposed and never exposed subjects). However, with the use of logistic regression, the determinants of skin reactivity to animals were atopy (p < 0.001), followed by cumulative duration of exposure to domestic animals (p < 0.01). The number of animals times the number of species times the duration of exposure was also a significant determinant of skin reactivity (p = 0.05). CONCLUSIONS: We conclude that beyond the predominant role of atopy, cumulative duration of exposure to domestic animals is a significant determinant for immediate sensitization to animal-derived antigens in subjects with asthma.

Adult↗
PubMed1991

Further evidence for the presence of "small eaters" and "large eaters" among women.

One hundred thirty-four women, aged 36 +/- 4 (mean +/- SD) y, BMI 20 +/- 3 kg/m2, perceiving themselves as having either a low or high energy intake (EI), participated in a study to determine variations in EI. Information on EI and activity level was obtained from repeated 7-d records. The 40 subjects with the lowest EI (in kcal/kg body wt) were categorized as small eaters (SEs); the 40 subjects with the highest EI were considered to be large eaters (LEs). The absolute (in kcal) and relative (in kcal/kg body wt) EIs of the SE and LE groups were 1488 +/- 312 and 27 +/- 4 for the SE group, respectively and 2393 +/- 509 and 47 +/- 6 for the LE group, respectively. There was no significant difference in activity level or fat-free mass (FFM) between the groups. However, LEs weighed significantly less (51 vs 55 kg) and were leaner (22% body fat vs 33%) than were SEs. Individuals with similar FFM and activity level can vary significantly in EI needs.

Adult↗
PubMed1991

[Acquiring power].

Many nurses are intimidated by the notion of power, as if it somehow doesn't apply to them. They have only to take stock of their vast store of knowledge, experience, and accomplishments over the years to put themselves on the path to empowerment. Author Claire Leblanc highlights some of the outstanding achievements of the nursing profession--for example, playing an active role in the reform of the health care system. She also talks about future challenges, with respect to the changing role of the nurse and the need for higher educational standards. Co-operation and a collective sense of professional pride are the keys.

Health Policy↗
PubMed1990

Using MZ twins in experimental research to test for the presence of a genotype-environment interaction effect.

Despite some evidence that genotype-environment interaction (G x E) effects may be involved in the variation observed in behavioral and biological traits, few attempts have been made to detect and quantify this component of genetic variation in humans. We propose that one way to achieve this goal is to challenge several genotypes in a similar manner, submitting both members of several MZ twin pairs to an ethically acceptable experimental treatment capable of inducing an adaptative response. In this situation, the G x E effect can be assessed with a two-way analysis of variance for repeated measures on one factor, the treatment effect. In this design, twins are considered nested within the pair, whereas the treatment effect is considered a fixed variable. The intrapair resemblance in the response to the treatment is quantified with an intraclass correlation coefficient computed with between-sibhips and within-sibhips means of squares. To illustrate this approach, changes induced by long-term endurance training were studied in 10 MZ twin pairs. Significant intrapair resemblance in the response of maximal oxygen uptake was observed, with about 7 to 8 times more variance between pairs than within pairs. This design with MZ twins may be helpful in the study of human variation for multifactorial phenotypes.

Environment↗
PubMed1990

Effect of intensity of physical activity on body fatness and fat distribution.

To evaluate the effect of intensity of physical activity on body fatness and fat distribution, observations of 1366 women and 1257 men who participated in the 1981 Canada Fitness Survey were analyzed. Subjects were tested for energy expenditure of leisure-time activities and estimated maximal oxygen uptake (VO2max), body fatness was measured by subcutaneous skinfold thicknesses, and anthropometric measurements were made. Subjects of both sexes were categorized into four subgroups on the basis of their participation in leisure-time activities of various intensities. In general, subjects practicing vigorous activities on a regular basis had lower subcutaneous skinfold thicknesses and waist-to-hip ratios (WHRs) than those not performing these activities. These differences remained statistically significant after a covariance analysis was used to remove the effect of total energy expenditure of leisure-time activities on subcutaneous fat and fat distribution. Moreover, the WHR remained significantly lower in subjects performing high-intensity exercise after the effect of subcutaneous fat on fat distribution was adjusted for.

Adipose Tissue↗
PubMed1990

Effect of dietary fat content on total and regional adiposity in men and women.

The relationship between dietary fat intake, adiposity and regional subcutaneous fat distribution was studied in 344 men and 335 women (aged 35-55 years). Three-day food records were used to estimate total energy intake (EI) and percent intake of all macronutrients. Subjects were categorized as having an EI that was low (lower quantile) or high (upper quantile) in fat. Results showed that both men and women with a higher percent of EI in the form of fat weighed significantly (P less than 0.05) more, and had higher subcutaneous adiposity indices than subjects with a low fat intake. There was also a significant difference for both sexes between low and high fat intake groups in trunk and extremity skinfolds and trunk/extremity skinfolds ratio adjusted for the sum of skinfolds. However, this effect was not present when correlations between percent fat intake and body composition or regional fat distribution variables adjusted for total fat intake per unit of body mass were computed. These results suggest that a greater EI in the form of fat influences total adiposity, as well as regional subcutaneous fat distribution, only when high fat consumers are compared to low fat consumers.

Adipose Tissue↗
PubMed1989

Genetic effect in resting and exercise metabolic rates.

Two studies dealing with the contribution of the genotype in individual differences for resting metabolic rate (RMR), thermic effect of a 4.2 MJ carbohydrate meal (TEM), and energy cost of submaximal exercise are reported. The genetic effect for RMR and TEM was studied in 31 pairs of parent-child, 21 pairs of dizygotic (DZ) twins, and 37 pairs of monozygotic (MZ) twins, whereas the heritability of the energy cost of submaximal exercise was determined from data on 22 pairs of DZ twins and 31 pairs of MZ twins. The heritability of RMR reached approximately 40% of the variance remaining after adjustment for age, gender, and fat-free mass, (FFM). The genetic effect for TEM was equivalent to at least 40% to 50% of the variation in the energy expended during four hours after the meal test. A highly significant genetic effect was found for fasting plasma glucose (greater than .72), but the results for fasting plasma insulin are unclear. No significant genetic variance was seen for the glucose and insulin response to the carbohydrate meal. Finally, heritability for the metabolic rate during cycle exercise was high (greater than or equal to .46) at low power output, but it became nonsignificant when the energy cost reached about 6 times the RMR.

Adolescent↗
PubMed1989

Genetic and environmental influences on level of habitual physical activity and exercise participation.

In order to quantify genetic and environmental determinants of physical activity level, 1,610 subjects from 375 families who lived in the greater Québec city area completed a three-day activity record in 1978-1981. Level of habitual physical activity, which includes all the usual activities of life, and exercise participation, which includes activities requiring at least five times the resting oxygen consumption and more, were derived from this record. Familial correlations were computed in several pairs of biologic relatives and relatives by adoption after adjustment for the effects of age, sex, physical fitness, body mass index, and socioeconomic status, and analyzed with a model of path analysis that allows the separation of the transmissible effect between generations (t2) into genetic (h2) and cultural (b2) components of inheritance. The transmission was found to be statistically significant, but was accounted for by genetic factors for level of habitual physical activity (t2 = h2 = 29%), and by cultural factors for exercise participation (t2 = b2 = 12%). Although non-transmissible environmental factors remain the major determinants of these two physical activity indicators in this population, the results suggest that children can acquire from their parents certain customs regarding exercise behavior and that the propensity toward being spontaneously active could be partly influenced by the genotype.

Activities of Daily Living↗
PubMed1989

Body mass index as a discriminant function among health-related variables and risk factors.

A group of 206 subjects (30-55 years) were studied with the objective of quantifying the relationships between fitness indicators (relative body weight (BMI), aerobic power, muscular endurance), health indicators and risk factors, (appraised age, cost of health services consumed, blood pressure (SBP and DBP), blood lipids (CHO and HDL), cigarette smoking). BMI was significantly correlated with the risk indicators in the male sample (.302 less than or equal to r less than or equal to .364) and in the female sample (.217 less than or equal to r less than or equal to .521). All coefficients were in the direction of the established biological assumption as concerns hazards to health. The discriminant analysis revealed that in the total group of men, 77% (p less than or equal to .001) of the subjects could be classified either in high or low BMI (greater than Q75 or less than or equal to Q25) on the basis of the scores in SBP, HDL, HDL/CHO. In the subgroup of women greater than or equal to 40 years, statistically significant classification occurred in 100% of the cases (p less than or equal to .001) on the basis of DBP, CHO, HDL/CHO, NCIG. The results indicate that BMI is a fitness determinant which is valid, convenient and easy to use in the detection of unfavorable health indices and when clinical intervention is justified.

Adult↗
PubMed1989

Evidence for the existence of small eaters and large eaters of similar fat-free mass and activity level.

The objective of this study was to identify individuals of the same age, sex, activity level and fat-free mass who differed in their level of energy intake (EI). Estimates of energy intake and physical activity level were derived from three-day food and activity records from 430 individuals 17-54 years of age. Body composition was measured by underwater weighing and body fat and fat-free mass were obtained. Subjects were grouped into four categories based on age and sex (females aged 17-34 and 35-54 years and males aged 17-34 and 35-54 years). Subjects were identified as small eaters (SE) or large eaters (LE) according to kJ of EI per kg body weight, SE being from the lower quartile and LE from the upper quartile of their distributions. The results showed that, on average, LE consumed almost twice as many kJ per kg body weight as SE (about 200 versus 100). In addition middle-aged male and female SE were significantly (P less than 0.001) heavier than middle-aged male and female LE respectively. The mean body weight for the male SE was 82 +/- 12 kg (mean +/- s.d.) against 69 +/- 9 kg for the LE, while it was 66 +/- 10 kg against 52 +/- 5 kg for the female SE and LE. The male and female SE also had a significantly higher percentage body fat in both age groups. In general, there was no difference in fat-free mass and activity level between the SE and LE. It is concluded that there exist groups of individuals who have a considerable difference in their EI and adiposity even though they have similar levels of activity and fat-free mass.

Activities of Daily Living↗
PubMed1988

Effect of the amount of body fat on the age-associated increase in serum cholesterol.

This study investigates the contribution of body fat stores on the age-associated increase in serum cholesterol and triglyceride levels. Percentage of body fat was measured by hydrostatic weighing, and serum cholesterol, triglyceride, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol levels were determined in a sample of 472 healthy men and women ages 18-50 years. In both sexes, body fat mass was significantly correlated with serum cholesterol (r = 0.21 in men and r = 0.24 in women, P less than 0.01) and triglyceride (r = 0.33 in men and r = 0.24 in women, P less than 0.01) levels. After adjustment for the association between age and serum cholesterol, no correlation was observed between body fat mass and serum cholesterol (r = 0.01 in men and r = 0.09 in women). After correction for age, serum triglyceride levels remained significantly correlated with body fat mass (r = 0.26 and r = 0.17 in men and women, respectively, P less than 0.05). As body fat also increases with age, the possibility that a partial correlation coefficient procedure eliminated a portion of the age effect mediated by an age-related increase in fat, was addressed by performing further analyses. Within each sex subsample two sets of analyses were performed on (a) three groups of subjects individually paired for age but with different levels of body fat stores, and (b) three groups of subjects paired for the amount of body fat but differing in age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
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

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

Inter-generation transmission of physical fitness in the Canadian population.

Body weight, height, body mass index, skinfold measurements, waist-to-hip ratio (WHR), somatotype components, muscular endurance and strength, flexibility, resting heart rate and submaximal power output (PWC150/kg) were measured in 13,804 subjects during the 1981 Canada Fitness Survey. Familial correlations were computed to determine the contribution of transmissible (t2) and environmental (e2) factors in physical fitness by path analysis. Transmissibility estimates (t2) under 0.30 for weight, height, WHR and PWC150/kg, above 0.40 for mesomorphy, ectomorphy, push-up test and flexibility, and between 0.30 and 0.40 for the other measurements were obtained. These results suggest that e2 account for more than 50% of the variation and that the average total biological and cultural inheritance from parents to offspring in physical fitness of Canadians accounts for 30% to 40% of the phenotypic variation.

Adolescent↗