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Biomedical subjects

L Potvin

Publications and source records attributed to L Potvin.

At least 19 recordsLinked to original sources
PubMed2004

Program sustainability: focus on organizational routines.

Program sustainability is an ongoing concern for most people in health promotion. However, the current notion of sustainability in organizations, namely routinization, needs refinement. This article examines organizational routines. In so doing, it refines the notion of sustainability and the assessment of routines. Drawing on the organizational literature, a routinized program is defined by the presence of routinized activities, meaning that these activities exhibit four characteristics of organizational routines: memory, adaptation, values and rules. To answer the question of how these characteristics are useful, we conducted an empirical study of the routinization of the Quebec Heart Health Demonstration Project in five community health centers. Our method consisted of a multiple-case study. We observed project activities in each center in 2000. The data came from documents and interviews with project actors. Our results show that, in one of the centers, no resources had been officially committed to project activities. Even so, the actors continued some activities on an informal basis. In another center, the activities satisfied three of the four routine characteristics. In the three others, activities satisfied all of the characteristics. These results suggest focusing the study of program sustainability on the routinization of activities resulting from it. They indicate four distinct degrees of sustainability: (1) the absence of sustainability; no program activity is continued; (2) precarious sustainability; some residual activities are pursued, at least unofficially; (3) weak sustainability; the program produces some official activities that are not routinized; and (4) sustainability through routinization; routinized activities result from the program.

Community Health Centers↗
PubMed2001

Permeabilization of model lipid membranes by Bacillus sphaericus mosquitocidal binary toxin and its individual components.

The high larvicidal effect of Bacillus sphaericus (Bs), a mosquito control agent, originates from the presence of a binary toxin (Bs Bin) composed of two proteins (BinA and BinB) that work together to lyse gut cells of susceptible larvae. We demonstrate for the first time that the binary toxin and its individual components permeabilize receptor-free large unilamellar phospholipid vesicles (LUVs) and planar lipid bilayers (PLBs) by a mechanism of pore formation. Calcein-release experiments showed that LUV permeabilization was optimally achieved at alkaline pH and in the presence of acidic lipids. BinA was more efficient than BinB, BinB facilitated the BinA effect, and their stoichiometric mixture was more effective than the full Bin toxin. In PLBs, BinA formed voltage-dependent channels of approximately 100-200 pS with long open times and a high open probability. Larger channels (> or =400 pS) were also observed. BinB, which inserted less easily, formed smaller channels (< or =100 pS) with shorter mean open times. Channels observed after sequential addition of the two components, or formed by their 1:1 mixture (w/w), displayed BinA-like activity. Bs Bin toxin was less efficient at forming channels than the BinA/BinB mixture, with channels displaying the BinA channel behavior. Our data support the concept of BinA being principally responsible for pore formation in lipid membranes with BinB, the binding component of the toxin, playing a role in promoting channel activity.

Bacillus↗
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↗
PubMed2001

Assessing socioeconomic effects on different sized populations: to weight or not to weight?

OBJECTIVE: Researchers in health care often use ecological data from population aggregates of different sizes. This paper deals with a fundamental methodological issue relating to the use of such data. This study investigates the question of whether, in doing analyses involving different areas, the estimating equations should be weighted by the populations of those areas. It is argued that the correct answer to that question turns on some deep epistemological issues that have been little considered in the public health literature. DESIGN: To illustrate the issue, an example is presented that estimates entitlements to primary physician visits in Manitoba, Canada based on age/gender and socioeconomic status using both population weighted and unweighted regression analyses. SETTING AND SUBJECTS: The entire population of the province furnish the data. Primary care visits to physicians based on administrative data, demographics and a measure of socioeconomic status (SERI), based on census data, constitute the measures. RESULTS: Significant differences between weighted and unweighted analyses are shown to emerge, with the weighted analyses biasing entitlements towards the more populous and advantaged population. CONCLUSIONS: The authors endorse the position that, in certain problems, data analyses involving population aggregates unweighted by population size are more appropriate and normatively justifiable than are analyses weighted by population. In particular, when the aggregated units make sense, theoretically, as units, it is more appropriate to carry out the analyses without weighting by the size of the units. Unweighted analyses yield more valid estimations.

Age Factors↗
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↗