Biomedical subjects

L Potvin

Publications and source records attributed to L Potvin.

At least 19 recordsLinked to original sources

PubMed2001

Correlates and predictors of adiposity among Mohawk children.

BACKGROUND: High rates of Type 2 diabetes in Native populations underlie the need for research on risk factors, including physical activity (PA) and obesity. METHODS: In 1994 and in 1996, 103 girls and 95 boys [mean age (standard deviation): 7.5 (1.3) years] attending elementary schools in two Mohawk communities completed a questionnaire assessing demographic and lifestyle variables. In addition, height, weight, and subscapular skinfold thickness (SSF) were measured and children performed a run/walk fitness (R/W) test. Gender-specific multiple linear regression assessed the impact of baseline variables on the log of SSF at baseline and follow-up. RESULTS: In cross-sectional analyses among boys and girls, the common correlates of baseline SSF included failing to achieve the minimal fitness standard for the R/W test and being involved in summer sports. Additional correlates identified only among girls included excessive television watching, lower PA, and involvement in community sports. Longitudinal predictors among girls were younger age, being from the comparison community, excessive TV, and PA. Among boys, only baseline SSF predicted follow-up SSF. Girls who watched excessive TV had SSFs 30 and 14% greater than those who watched less TV at baseline and follow-up, respectively. CONCLUSION: TV viewing was the only consistent determinant of adiposity among girls.

Anthropometry↗

PubMed2000

Patient perception of quality following a visit to a doctor in a primary care unit.

BACKGROUND: Assessment of the quality of primary care services may be enhanced by including patient perceptions as well as professional judgment of quality. There is a need for reliable and valid instruments to measure these perceptions. OBJECTIVES: (i) To present a scale for measuring patient perception of quality of care following a visit to a doctor; and (ii) to analyse the responses given by patients recruited in primary care units in the Montreal region. The scale is composed of 22 items regrouped into three sub-scales referring to the patient-physician relationship (five items); the technical aspects of care (12 items); and the outcomes of the visit (five items). Distinctive features of the scale are that it focuses on patients' opinions about quality rather than on satisfaction, and that it includes items related to outcomes of the visit. METHODS: A survey was conducted on 473 patients who visited a physician in 11 primary care units in the Montreal region. Randomly selected patients received mailed questionnaires 5-7 days following their visit. Various statistical procedures were used to assess the reliability and the validity of the global scale and the sub-scales, and to analyse patients' patterns of response. RESULTS: The analysis of the psychometric properties of the global scale and the three sub-scales provides favourable evidence concerning their reliability and validity. The results of the factor analysis, the inter-item correlations and the Cronbach's alpha coefficients all support the distinction made between the interpersonal processes, the technical processes and the outcomes, and, at the same time, confirm the complex nature of the notion of perceived quality. The analysis of patients' responses allows the identification of items associated with global perception about quality of care. This global perception results from patients' perception of the physician's professional and interpersonal skills as well as from the outcomes of care. CONCLUSION: The scale can be used by physicians or primary health care units and has a wide range of applications.

Attitude to Health↗

PubMed2000

Knowledge of cardiovascular disease risk factors among the Canadian population: relationships with indicators of socioeconomic status.

BACKGROUND: We examined the ability of adult Canadians to recall cardiovascular disease risk factors to determine the associations between their ability to recall risk factors for cardiovascular disease and their socioeconomic status. METHODS: This study used the database assembled by the Canadian Heart Health Surveys Research Group between 1986 and 1992--a stratified representative sample comprising 23,129 Canadian residents aged 18 to 74. Nurses administered a standard questionnaire asking respondents to list the major risk factors for cardiovascular disease: fat in food, smoking, lack of exercise, excess weight, elevated blood cholesterol and high blood pressure. Six logistic regressions examined the multivariate associations between ability to recall each risk factor with education, income adequacy, occupation, sex, age, marital status and province of residence. RESULTS: More people knew about the behaviour-related risk factors for cardiovascular disease than about the physiologic risk factors: 60% recalled fat in food, 52% smoking and 41% lack of exercise, but only 32% identified weight, 27% cholesterol and 22% high blood pressure. Education was the socioeconomic status indicator most strongly and consistently associated with the ability to recall risk factors for cardiovascular disease. The odds ratios of reporting an association of the risks between people with elementary education and those with university degrees varied between 0.16 (95% confidence interval 0.12 to 0.22) for lack of exercise to 0.55 (95% confidence interval 0.39 to 0.77) for smoking. INTERPRETATION: People in categories at greater risk of cardiovascular disease, such as those aged 65 or more or those with only elementary education, are less able to recall important cardiovascular disease risk factors.

Adolescent↗

PubMed1999

A 10-year study of mortality in a cohort of patients with myotonic dystrophy.

OBJECTIVE: To determine the age and causes of death as well as the predictors of survival in patients with myotonic dystrophy (DM). METHODS: In a longitudinal study, a cohort of 367 patients with definite DM was followed for 10 years. RESULTS: During the 10-year period, 75 of the 367 DM patients (20%) died. The mean age at death (53.2 years, range 24 to 81) was similar for men and women. Among these 75 patients, 32 (43%) died of a respiratory problem, 15 (20%) of cardiovascular disease, 8 (11%) of a neoplasia, and 8 (11%) died suddenly. The ratio of observed to expected deaths was significantly increased to 56.6 (95% confidence interval [CI] 38.7 to 78.0) for respiratory diseases, 4.9 (95% CI 2.7 to 7.7) for cardiovascular diseases, and 2.5 (95% CI 1.1 to 4.6) for neoplasms. The mean age at death was 44.7 years for the childhood phenotype of DM, 47.8 years for the early-adult, 55.4 years for the adult, and 63.5 years for the mild phenotype (F = 4.8, p = 0.005). The age-adjusted risk of dying was 3.9 (95% CI 1.3 to 11.0) times greater for a patient with a distal weakness and 5.6 (95% CI 2.2 to 14.4) times greater for a patient with proximal weakness as compared with a person without limb weakness. CONCLUSIONS: Life expectancy is greatly reduced in DM patients, particularly in those with early onset of the disease and proximal muscular involvement. The high mortality reflects an increase in death rates from respiratory diseases, cardiovascular diseases, neoplasms, and sudden deaths presumably from cardiac arrhythmias.

Adolescent↗

PubMed1999

Anthropometric characteristics of Mohawk children aged 6 to 11 years: a population perspective.

OBJECTIVE: Recent studies have concluded that Native North American children have higher proportions of overweight and obesity than children from the general North American population. This study presents anthropometric data on a representative sample of children from the Mohawk Nation that can be used for comparison with other Native American populations. DESIGN: This is a cross-sectional study comparing distributions of anthropometric characteristics of Mohawk children to the corresponding age and gender data from the Second National Health and Nutrition Examination Survey (NHANES II). Weight, height, triceps and subscapular skinfold thickness, and waist and hip circumferences were measured in 527 children. SUBJECTS/SETTING: All children in grades 1 to 6 (aged 6 to 11 years) in the 3 elementary schools of 2 Mohawk communities in Canada, for whom parental consent was obtained, were enrolled in the present study. There were no exclusion criteria. With a participation rate of 83%, the 527 children enrolled in this study represent an unbiased sample of the population from 2 Mohawk territories. RESULTS: Compared with children studied in NHANES II, Mohawk children were similar in height and triceps skinfolds but were generally heavier, had thicker subscapular skinfolds, and had greater waist and hip circumferences. These differences were greater in older children. Mohawk children who had extreme-high weight values compared with their population means were heavier than their NHANES II counterparts. APPLICATIONS/CONCLUSIONS: Results indicated that, on average, Mohawk children seem to be slightly heavier than children in NHANES II. Except for those with extreme overweight values, Mohawk children show less variation of weight and body mass index than children in NHANES II. Finally, overweight Mohawk children seem to be more likely to carry their excess body fat truncally, compared with overweight children from NHANES II. Health practitioners working with Native American populations should be careful when assessing childhood obesity. Simple comparisons of weight or body mass index with NHANES standards may lead to inappropriate risk assessments.

Anthropometry↗

PubMed1999

Depressive symptoms in the late postpartum among low socioeconomic status women.

BACKGROUND: Postpartum depression has been the focus of much research in the past 15 years, but little is known about factors associated with depression of longer duration or later onset. The purpose of this longitudinal study was to analyze the relationship between stressful life conditions and postnatal depression in a group of women of low socioeconomic status from the third week to the sixth month postpartum. METHODS: Nulliparas who met criteria for low socioeconomic status were recruited from the prenatal care clinics of four Montreal hospitals. Questionnaires were verbally administered in the home at 30 weeks' gestation, at 3 and 9 weeks postpartum, and at 6 months postpartum. Blockwise multiple linear regression analyses were performed by entering predictor variables that included sociodemographic characteristics, chronic stressors, life events, and social support network. RESULTS: Sixty-eight women participated in the study. At 6 months postpartum, 38.2 percent of the mothers had a Beck Depression Inventory score of 10 or more. After accounting for previous depression, analyses indicated that chronic stressors (maternal health problems, infant difficulty, lack of money for basic needs, frequent conflicts with network members) and poor social support (informational and emotional) were associated with postnatal depressive symptoms. CONCLUSIONS: Health practitioners should recognize that high depressive symptomatology frequently occurs among low socioeconomic status first-time mothers at six months postpartum. Chronic stressors and inadequate social support are the most important factors associated with this problem.

Adult↗

PubMed1999

Socio-environmental factors and postnatal depressive symptomatology: a longitudinal study.

This study analyses the relationships between stressful life conditions and postnatal depressive symptomatology in a group of women of low socioeconomic status (SES) and a group of women of high SES from the third to the ninth week postpartum. Nulliparous pregnant women were recruited from the prenatal care clinics of four hospitals. Multiple linear regression analyses demonstrated that after accounting for SES group membership and depressive symptomatology during pregnancy, early postnatal chronic stressors (frequent conflictual episodes with network members, maternal health problems) and social support were linked to later postnatal depressive symptomatology.

Case-Control Studies↗

PubMed1998

Cry1Ac, a bacillus thuringiensis toxin, triggers extracellular Ca2+ influx and Ca2+ release from intracellular stores in Cf1 cells

Intracellular Ca2+ concentration was measured in single Cf1 cells (Choristoneura fumiferana, spruce budworm) loaded with Fura-2, a Ca2+-sensitive fluorescent probe. Cf1 cells displayed Ca2+ surges in response to Cry1Ac and Cry1C proteins, two Cf1-toxic Bacillus thuringiensis products, but not to Cry1Aa and Cry3A, which are not toxic to Cf1 cells. In the presence of extracellular Ca2+, the toxin-induced Ca2+ response was insensitive to methoxyverapamil, a voltage-dependent Ca2+ channel blocker, but was abolished by lanthanum, a general inhibitor of Ca2+ transport. In the absence of external Ca2+, Cry1Ac induced a small intracellular Ca2+ transient which was inhibited by TMB-8, a blocker of Ca2+ release from inositol-1,4,5-trisphosphate-sensitive pools. Under these conditions, thapsigargin, which inhibits intracellular Ca2+-ATPases, elicited a Ca2+ surge when applied alone. However, subsequent addition of Cry1Ac failed to induce a Ca2+ signal, indicating a depletion of intracellular Ca2+ pools. In Cf1 cells, therefore, bioactive B. thuringiensis toxins triggered intracellular Ca2+ surges which were mainly due to the influx of extracellular Ca2+ through toxin-made pores, as confirmed by planar lipid bilayer experiments. Furthermore, TMB-8- and thapsigargin-sensitive Ca2+ stores contributed to the Cry1Ac-induced Ca2+ signal.

Journal Article↗

PubMed1998

Family process in health research: extending a family typology to a new cultural context.

To describe family context in health research, the authors tested a typology of families developed in California with a sample of families in Quebec, Canada. Family scales from the California study were submitted to focus groups, translated, and standardized on a sample of 209 parents. A panel of experts then revised the scales to make them relevant to Quebec families and to health promotion. Data from the new and revised scales were collected on 509 Quebec couples (1,018 spouses) and were clustered separately by gender, using K means. The procedure classified all respondents into family types that paralleled the original typology. Discriminant analyses indicated that family profile variables significantly distinguished family types. Comparisons with family, stress, and health variables further differentiated among the types and expanded their meaning. The study demonstrates a method for redefining and extending family data in health research with different cultural groups.

Adult↗

PubMed1998

Measuring lay people's perceptions of the quality of primary health care services in developing countries. Validation of a 20-item scale.

INTRODUCTION: Methodologies that have been developed and validated in accordance with accepted scientific standards are needed to monitor and assess the quality of primary health care in developing countries. OBJECTIVE: To present the results of reliability and validity testing of a new instrument of measurement intended to document the user's opinion on the quality of primary health care services. METHODS: The 20-item scale includes three subscales related to health care delivery personnel and facilities. There were 241 people in one city and two villages in Upper Guinea who responded to the questionnaire. An item analysis preceded the test of psychometric properties of the three subscales and of the total score. Reliability was estimated by analyses of internal consistency and the Cronbach's alpha coefficient. A variety of statistical procedures were used to test factorial validity, trait validity (convergent and discriminant) and nomological validity. RESULTS: The reliability of the subscales ranged from 0.71 to 0.88. The validity analyses supported the initial dimensionality and suggested good construct validity. CONCLUSION: Results confirm the value of the use of the scale developed and highlight the need to take into account the diversity of how quality is perceived by lay people in developing countries. It is suggested that the process of formalization of this type of measurement scale be pursued.

Adult↗

PubMed1998

Developing a Code of Research Ethics for research with a Native community in Canada: a report from the Kahnawake Schools Diabetes Prevention Project.

This paper describes the background and evolution of a Code of Research Ethics that was developed for a primary diabetes prevention project in the Native Mohawk community of Kahnawake in Canada. Embodying the principles of participatory research, this code was written by the researchers in conjunction with the community in the first year of the three-year project. The code ensures that the community is a full partner for the entire research process. For this project a Community Advisory Board is representative of the community.

Canada↗

PubMed1998

Are drivers with CVD more at risk for motor vehicle crashes? Study of men aged 45 to 70.

OBJECTIVE: To examine whether male drivers aged 45 to 70 years suffering from cardiovascular disease (CVD) are more likely to be involved in motor vehicle crashes (MVC) that are reported to the police. DESIGN: Population-based case-control study. SETTING: Data on drivers' ages and medical conditions were compiled from the Societé de l'assurance automobile du Québec's (SAAQ) computerized files. A questionnaire was mailed to all subjects to collect additional information on annual distances driven and various driving behaviours. PARTICIPANTS: Age-stratified population-based random sample. Subjects were 2504 drivers involved in MVCs during a 6-month period; controls were 2520 drivers not involved in crashes. MAIN OUTCOME MEASURES: Proportion of drivers with CVD involved in MVCs. RESULTS: Response rate to the questionnaire was 35.5%. Analysis of the SAAQ files' entire sample of 5024 drivers showed that drivers suffering from CVD were less likely to be involved in MVCs (odds ratio [OR] 0.82, 95% confidence interval [CI] 0.67 to 0.99) than drivers without CVD. Although the estimate of risk remains unchanged when adjusted for age, it becomes statistically insignificant. It also remains unchanged and statistically insignificant when adjusted for yearly distance driven and driver behaviour, as shown by responses to the questionnaire. Drivers suffering from CVD drove significantly less each year (8900 km) than drivers without medical conditions (13,000 km). CONCLUSION: This study shows no increased risk of motor vehicle crashes for drivers suffering from CVD.

Accidents, Traffic↗

PubMed1998

Psychological distress and use of ambulatory medical services in the Quebec Medicare system.

OBJECTIVE: To document the impact of psychological distress symptoms on the use of ambulatory medical services in a universal insurance coverage context. DATA SOURCES: Data from the Quebec Health Survey (1987) linked with billing data from the Quebec Medicare system. The time frame for the utilization variables is one year before and one year after the QHS survey. STUDY DESIGN: LISREL was used to test a model introducing perceived health need as an explanatory factor of the relationship between psychological distress and the number of visits to a physician. Two samples were formed from the matched file. Sample A (n = 2,000) was used in an exploratory phase to adequately specify the model. Sample B (n = 2,000) was used to confirm the results obtained with Sample A. PRINCIPAL FINDINGS: The proposed model explained 35 percent of the number of visits to a physician in Sample A and 24 percent in Sample B. The effect of psychological distress symptoms on the respondent's perceived health need was as important as the effect of physical health status. The effect of the respondent's previous health services utilization on the number of visits to a physician was also significant. CONCLUSIONS: These results may be interpreted to indicate that in a universal insurance coverage context, psychological distress is a significant predictor of perceived health need.

Adolescent↗

PubMed1997

Risk stratification after myocardial infarction using signal-averaged electrocardiographic criteria adjusted for sex, age, and myocardial infarction location.

BACKGROUND: The objectives were to investigate the factors influencing signal-averaged ECGs (SAECGs) recorded in patients after myocardial infarction (MI) and to develop criteria for predicting arrhythmic events (AEs) that account for these factors. METHODS AND RESULTS: SAECGs were recorded 5 to 15 days after MI in 2461 patients without bundle-branch block. The duration (QRSd), terminal potential (VRMS), and terminal duration (LAS) of the filtered QRS were measured. During follow-up (17 +/- 8 months), AEs (arrhythmic death; ventricular tachycardia, VT; ventricular fibrillation, VF) occurred in 80 patients (3.3%). Receiver operating characteristic curves showed that QRSd discriminated patients with all types of AEs, but VRMS and LAS discriminated only VT patients; QRSd minus LAS also discriminated AE patients. Sex, age, and MI location significantly affected the SAECG; survivors without VT or VF were divided into subgroups (2 sex x 4 age x 2 MI), and QRSd values exceeding the 70th percentile in each subgroup predicted AEs with a sensitivity of 65.4%. An unadjusted QRSd criterion showed the same overall sensitivity and specificity but with less uniform values for each subgroup. A Cox model was constructed by use of multiple prognostic indicators, and in rank order, QRSd, previous MI, and Killip class were predictive of AEs. CONCLUSIONS: SAECG adjustments for sex, age, and MI location did not improve sensitivity and specificity but produced a more uniform predictive performance. The proposed criteria are based only on QRSd, because late potentials (VRMS and LAS) did not discriminate patients with sudden death. Duration of high-level activity during QRS (QRSd-LAS) can predict AEs, suggesting that the arrhythmogenic substate involves a large mass of myocardium.

Age Factors↗

PubMed1997

Prevalence of stages of change for physical activity in rural, suburban and inner-city communities.

This study documented the differing prevalence rates for stages of change for physical activity across rural, suburban and inner city communities using survey methods and controlling for education, gender and disease status. Respondents (n = 4768) were participants in the baseline survey for the evaluation of the Québec Heart Health Demonstration Project, a health promotion program implemented in various communities throughout the province of Québec. A total of 2639 female and 2087 male parents answered a questionnaire they received from their grade 4 to grade 6 children. The questionnaire dealt with demographic information, health-related behaviors, and intentions for these behaviors. The response rates were 90%, 77% and 70% in the rural, suburban and inner city communities respectively. Results showed that prevalence rates differed significantly between communities with rural communities having the highest rates of readiness for physical activity in comparison to suburban and inner city communities. These findings suggest that above and beyond individual difference variables, structural components such as type of community are related to people's readiness for physical activity involvement.

Adult↗

PubMed1997

Regular exercise in 30- to 60-year-old men: combining the stages-of-change model and the theory of planned behavior to identify determinants for targeting heart health interventions.

The theory of planned behavior and the stages-of-change model were used to gain a clearer understanding of the factors associated with regular exercise in order to plan more effective programs in heart disease prevention. The study was conducted using a self-administered postal questionnaire sent to a sample of 2,269 men 30 to 60 years of age. Nearly a quarter (23.3%) of respondents were physically inactive, of whom 10.5% were in the precontemplation and 12.8% in the contemplation stages; 42.1% exercised less than twice a week, of whom 22.4% were in the preparation I and 19.7% in the preparation II stages. Only 34.6% were in the action stage, exercising regularly for at least 20 minutes twice a week or more with the intention of continuing to do so. Logistic regression indicated that the variables derived from the theory of planned behavior, namely attitude, subjective norm and perceived behavioral control, were differently associated with the stages of behavior. Perceived behavioral control was strongly significant in all stages. Attitude was related with stages in which individuals have intention of exercising (contemplation and preparation II). In contrast, subjective norm seemed to be associated with stages in which individuals have no intention of doing so (precontemplation and preparation I). By identifying the specific needs of sub-groups, the results can help define programs most likely to accelerate men to the stage of regular exercise, part of an effective strategy for heart health promotion in this high-risk population.

Adult↗

PubMed1997

Single-site mutations in the conserved alternating-arginine region affect ionic channels formed by CryIAa, a Bacillus thuringiensis toxin.

The role of the third domain of CryIAa, a Bacillus thuringiensis insecticidal toxin, in toxin-induced membrane permeabilization in a receptor-free environment was investigated. Planar lipid bilayer experiments were conducted with the parental toxin and five proteins obtained by site-directed mutagenesis in block 4, an arginine-rich, highly conserved region of the protein. Four mutants were constructed by replacing the first arginine in position 21 by a lysine (R521K), a glutamine (R521Q), a histidine (R521H), or a glutamic acid (R521E). A fifth mutant was obtained by replacing the fourth arginine by a lysine (R527K). Like CryIAa, the mutants formed cation-selective channels. A limited but significant reduction in channel conductance was observed for all mutants except R521H. The effect was more dramatic for the voltage dependence of the channels formed by R521K and R521Q, which was reversed compared to that of the parental toxin. This study provides the first direct evidence of a functional role for domain III in membrane permeabilization. Our results suggest that residues of the positive arginine face of block 4 interact with domain I, the putative pore-forming region of CryIAa.

Amino Acid Sequence↗

PubMed1996

Diet and exercise profiles of 30- to 60-year-old male smokers: implications for community heart health programs.

The aim of this study was to estimate the prevalence of diet and exercise behaviors in middle-aged male smokers and identify their determinants of behaviors, with the ultimate goal of designing more effective interventions in a community heart health program. Self-administered, postal questionnaires produced a sample of n = 671 male smokers, 30 to 60 years of age residing in Laval, Quebec's second most populous city. Variables for the study were derived from the theory of planned behavior. Correspondence analysis explained 65% of the variance, classifying smokers into five groups based on diet and exercise behavior. Group 1, smokers with diet and exercise behaviors deemed inadequate for heart health, comprised 43% of the total. Groups 2 and 3, smokers with a diet deemed inadequate or needing improvement respectively, and Group 4, smokers with inadequate exercise, comprised 42% of the total. Group 5, smokers with neither of the other high-risk behaviors, comprised 15% of the total. Four significant variables contrasted Groups 1 to 4 with group 5: age, number of cigarettes smoked daily, and perceived behavioral control (PBC) in both diet and exercise. However, coefficients for age and smoking were weak for all groups. Coefficients for PBC in diet were high and negative only for smokers with an inadequate one. For PBC in exercise, they were high and negative only for smokers who exercised inadequately. Intervention groups based on specific deficiencies in diet and exercise behaviors were then identified. Therefore, the results suggest that smoking cessation programs may be made more effective by targeting specific sub-groups and by providing resources and opportunities to counteract the lack of perceived behavioral control in middle-aged male smokers vis-a-vis diet and exercise.

Adult↗