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Biomedical subjects

L Potvin

Publications and source records attributed to L Potvin.

At least 55 records · Page 3Linked to original sources
PubMed1993

Why alert residents are more or less willing to cohabit with cognitively impaired peers: an exploratory model.

This study tested a model of the willingness of alert residents to cohabit with cognitively impaired peers in nursing homes. A systematic sample of 435 alert residents living on mixed care units selected in 19 nursing homes were interviewed. Four factors were of particular influence on the willingness to cohabit: alert residents' negative emotional reactions to living with the cognitively impaired, their knowledge of confusion, disturbance generated by dysfunctional behaviors, and benefits of cohabitation for the cognitively impaired as perceived by alert residents.

Aged↗
PubMed1993

Factors influencing the practice of vaginal birth after cesarean section.

OBJECTIVES: Vaginal birth after cesarean has been recommended for most women with previous cesarean sections for the past 10 years. This practice, however, has not yet been generalized because high variations can still be observed among countries, hospitals, and physicians. METHODS: A case-control study involving 635 case patients and 2593 control patients was carried out to determine which characteristics of the physician, the patient, or the hospital were important in the adoption of this practice. RESULTS: The results of the multiple stepwise logistic regression analysis indicate a higher likelihood that women will experience vaginal birth after cesarean if their physicians had cesarean rates under 20%, had less than 5% of their patients considered at risk, and were younger than 54 years old. Vaginal birth after cesarean was also favored by hospitals characterized by a high degree of neonatal and obstetrical specialization, and a patient population with a low level of education. CONCLUSIONS: This policy is still in the developmental stage, as evidenced by the great variability between hospitals and physicians in rates of vaginal birth after cesarean. Further efforts are required for this policy to become the norm.

Adult↗
PubMed1992

Blockade of insulin sensitive steady-state R-type Ca2+ channel by PN 200-110 in heart and vascular smooth muscle.

The effect of high K+ concentration, insulin and the L-type Ca2+ channel blocker PN 200-110 on cytosolic intracellular free calcium ([Ca2+]i) was studied in single ventricular myocytes of 10-day-old embryonic chick heart, 20-week-old human fetus and rabbit aorta (VSM) single cells using the Ca(2+)-sensitive fluorescent dye, Fura-2 microfluorometry and digital imaging technique. Depolarization of the cell membrane of both heart and VSM cells with continuous superfusion of 30 mM [K+]o induced a rapid transient increase of [Ca2+]i that was followed by a sustained component. The early transient increase of [Ca2+]i by high [K+]o was blocked by the L-type calcium channel antagonist nifedipine. However, the sustained component was found to be insensitive to this drug. PN 200-110 another L-type Ca2+ blocker was found to decrease both the early transient and the sustained increase of [Ca2+]i induced by depolarization of the cell membrane with high [K+]o. Insulin at a concentration of 40 to 80 microU/ml only produced a sustained increase of [Ca2+]i that was blocked by PN 200-110 or by lowering the extracellular Ca2+ concentration with EGTA. The sustained increase of [Ca2+]i induced by high [K+]o or insulin was insensitive to metabolic inhibitors such as KCN and ouabain as well to the fast Na+ channel blocker, tetrodotoxin and to the increase of intracellular concentrations of cyclic nucleotides. Using the patch clamp technique, insulin did not affect the L-type Ca2+ current and the delayed outward K+ current. These results suggest that the early increase of [Ca2+]i during depolarization of the cell membrane of heart and VSM cells with high [K+]o is due to the opening and decay of an L-type Ca2+ channel. However, the sustained increase of [Ca2+]i during a sustained depolarization is due to the activation of a resting (R) Ca2+ channel that is insensitive to lowering [ATP]i and sensitive to insulin.

Animals↗
PubMed1992

The Roseto effect: a 50-year comparison of mortality rates.

OBJECTIVES: Earlier studies found striking differences in mortality from myocardial infarction between Roseto, a homogeneous Italian-American community in Pennsylvania, and other nearby towns between 1955 and 1965. These differences disappeared as Roseto became more "Americanized" in the 1960s. The present study extended the comparison over a longer period of time to test the hypothesis that the findings from this period were not due to random fluctuations in small communities. METHODS: We examined death certificates for Roseto and Bangor from 1935 to 1985. Age-standardized death rates and mortality ratios were computed for each decade. RESULTS: Rosetans had a lower mortality rate from myocardial infarction over the course of the first 30 years, but it rose to the level of Bangor's following a period of erosion of traditionally cohesive family and community relationships. This mortality-rate increase involved mainly younger Rosetan men and elderly women. CONCLUSIONS: The data confirmed the existence of consistent mortality differences between Roseto and Bangor during a time when there were many indicators of greater social solidarity and homogeneity in Roseto.

Adult↗
PubMed1992

[Intervention framework of the Quebec Healthy Heart Demonstration Project].

Cardiovascular diseases are Canada's primary cause of death and hospitalisation, and are the second major cause of restricted physical activity. Quebec province, with a mortality rate of 399/100,000, has figures even higher than the national average of 323/100,000, and 7 out of every 10 Quebecois present at least one of the major cardio-vascular risk factors. Following an exploratory task force on this question, the Canadian government initiated a partnership programme with the provinces wherein the federal government and provincial governments would each contribute one million Canadian dollars over a five year period for heart disease prevention programmes. Quebec province selected three different projects in which multifactorial, multisectorial community-based programmes were to be implemented. The sites chosen for the projects were: a rural region situated on the banks of the St. Laurence River, a Montreal suburban district, and a multi-ethnic, socio-economic disadvantaged community in downtown Montreal. Despite a common public health approach and the ultimate goal of improving heart health through the lowering of risk factors, each project had its own specific major intervention strategy and primary target population. The projects were linked by a study design to evaluate community and family mechanisms which favour the adoption of low risk behaviours. A coordinating committee was formed to supervise the overall project which included strategic planning, consultancy services to project staff, methodology, development and implementation, and evaluation. Each specific project team was free, however, to choose its particular orientations.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular Diseases↗
PubMed1991

Estimating the reliability of continuous measures with Cronbach's alpha or the intraclass correlation coefficient: toward the integration of two traditions.

The epidemiological literature has been ambiguous concerning reliability estimates for continuous variables. Reproducibility and internal consistency have been presented as different aspects of reliability, the former being estimated with some form of intraclass correlation coefficient, the latter with Cronbach's alpha. Based on demonstrations available in the literature this paper recalls that both estimates are based on the same measurement model and on the same definition of reliability. It also highlights the conditions under which they are equivalent and provides practical suggestions concerning the estimation of reliability, based on design considerations.

Analysis of Variance↗
PubMed1990

[Neuromuscular disorders].

In this study, the author focuses on three neuromuscular disorders that have historically been isolated to a specific region in Québec. The author is convinced that appropriate nursing interventions can help in the detection of these disorders and can, using data on social behavior, help eliminate harmful genetic mutations.

Health Education↗
PubMed1988

Mandatory driver training and road safety: the Quebec experience.

In January 1983, the Quebec Government made driver training courses mandatory for any person seeking a first driver's license. Using accident and licensure data over a five-year period, we conducted an evaluation of the impact of the enactment of mandatory driver training on: the risk of accident for newly licensed drivers; the mortality and morbidity of these accidents; the number of new drivers; and the mean age of licensure. Results of our time series analyses show that this legislation had no appreciable effect on the risk of accident or on the mortality/morbidity rate per accident for newly licensed drivers aged 18 and over. However, since 1983, the number of women under 18 years of age getting their first driver's license has increased by 20 per cent, and their mean age has decreased from over 18 to under 18. Mandatory driver training may have increased the numbers and risks of accidents for young, primarily female, drivers.

Accidents, Traffic↗
PubMed1985

Effect of antigen stimulation on antigen-specific IgE-plaque-forming cells from peripheral-blood lymphocytes of atopics.

In the present study, it was shown that allergen challenge in vitro produced an increase in the number of antigen-specific IgE-plaque-forming cells of peripheral-blood lymphocytes from grass- or ragweed-allergic patients. Thus, the blood lymphocytes of all twelve (four rye grass I and eight AgE) sensitive donors responded whereas the blood lymphocytes of five non-atopic controls were unresponsive to antigen challenge. Allergen challenge doses of 10(-10)-10(-12) g/ml were found to give the greatest number of plaque-forming cells whereas the number of plaque-forming cells at challenging doses between 10(-9) and 10(-7) g/ml were either the same or less than those obtained with unchallenged cells. The results are discussed as to whether this in vitro model system represents in vivo response to allergen of the allergic patient.

Antibody-Producing Cells↗
PubMed1985

Detection of antigen-specific IgE-plaque-forming cells from peripheral-blood lymphocytes of ragweed- and grass-allergic patients.

The reverse haemolytic plaque assay was developed to measure antigen (AgE or rye grass I)-specific IgE-plaque-forming cells from the peripheral-blood lymphocytes of ragweed- and grass-allergic patients. The anti-IgE-developing antisera was shown to be isotype-specific, and the response of the assay was inhibited by 52% by the addition of 10 pg of antigen. In addition, the assay was shown to have a reproducibility (s.d.) of 15%. The blood lymphocytes from all fifteen atopic (grass and ragweed) patients were shown to form antigen-specific IgE-plaque-forming cells during the pollen season (mean value 115 cells) and up to 6 months after the season (mean value 56 cells). Cycloheximide appears to block the formation of the plaque-forming cells. This method appears to be sensitive and reproducible enough to study in vitro IgE antibody synthesis of peripheral-blood lymphocytes from atopics.

Antibody Specificity↗
PubMed1980

Role of T gamma and T mu sub-set lymphocytes in allergic disease.

In the present study, 48 students (30 non-atopics and 18 rhinitic allergic individuals) were studied for relative concentrations of T (E-rosette-forming sheep red blood cells) and T mu and T gamma sub-sets. Insignificant differences in T-cells were found between the two groups and only slightly higher T mu and slightly lower T gamma relative concentrations were observed. However, examinations of T mu/T gamma ratios for each individual revealed a strikingly higher ratio between these two groups, particularly in those individuals whose IgE exceeded 200 u/ml. Interpretation of the role of the T mu and T gamma sub-sets, particularly with regard to helper and supressor activities in allergic disease, is discussed in the text.

Adolescent↗
PubMed1979

Immunoglobulin E response during viral infections.

One hundred and three patients (90 nonatopics and 13 atopics) with respiratory infections to various viral agents were studied retrospectively with respect to IgE immunoglobulin levels during acute (1 to 7 days) and convalescent (8 to 30 days) phases of infection. It was found that 59% of patients had a decrease of 20% or more in IgE level, 27% remained the same, and only 14% showed a rise 20% or more from the acute to the convalescent phases of infection. IgE levels decreased up to 3 to 4 wk after symptoms and the degree of decrease was more apparent for the nonatopics who had higher IgE levels in their acute phase of infection. Less dramatic decrease in IgE was observed for the 13 atopics studied. The changes in IgE levels during the viral infectious period are discussed in terms of possible cellular mechanisms that may control IgE immunoglobulin.

Acute Disease↗
PubMed1978

A study on the IgE levels of military recruits and association with HLA antigens.

To identify antigen marker(s) on lymphocytes for the immunoregulation of IgE immunoglobulin. For this purpose, IgE determinations were performed on 58 recruits who were arbitrarily selected for HLA typing. Thirty-three recruits with IgE values ranging from 24 to 142 U/ml (71 U/ml (71 U/ml average) showed a slight increase in incidence for HLA-A23, -A33 and BW-15 when compared to a group of 25 recruits whose IgE values ranged from 153 to 2128 U/ml (615 U/ml average). Examination for C-loci specificity indicated that CW-1, CW-3 and CW-4 similar for both groups; however, the "low" IgE group had a frequency of 55.5% of recruits possessing CW-2 antigen compared with only 15% for the "high" group. The value for the "high" IgE appears to be similar to that of the normal population (10% incidence) and only slightly elevated when compared to 7% (2/29) found when the identical CW-2 antisera were tested with laboratory personnel. Thus the associations of HLA-CW2 with the recruits within the "low" IgE group suggests that this HLA marker may be an expression for a suppressed response for IgE immunoglobulin. Viral and bacterial infections, found frequently in these recruits, are discussed as a possible cause of this suppression.

HLA Antigens↗
PubMed1978

Viral infections and IgE levels.

Six non-atopic patients with respiratory infections to a variety of viruses demonstrated a consistent drop in IgE levels (35% to 87%) in the convalescent phase compared to the acute phase of infection, suggesting that the viral agent affects T lymphocytes to suppress and hence B lymphocytes to secrete IgE immunoglobulin.

Asthma↗
PubMedDate not supplied

Medical conditions and the risk of motor vehicle crashes in men.

OBJECTIVE: To determine whether men aged 45 to 70 years with any medical condition are at an increased risk of involvement as drivers in police-reported motor vehicle crashes. DESIGN: Case-control study. SETTING: Province-wide population-based sampling. PARTICIPANTS: A total of 2504 drivers randomly selected from those involved as a driver in a motor vehicle crash (cases) and 2520 men not involved in a crash (controls) during a 6-month period. DATA COLLECTION: The Societé de l'assurance automobile du Quebec (SAAQ) computerized files provided data on crashes, age, and medical conditions. A mailed questionnaire elicited information on usual mileage and driving conditions. RESULTS: Data from the SAAQ files were obtained for all 5024 drivers. The overall response rate to the mailed survey was 35.5% with no statistically significant differences in the distribution of characteristics between respondents and nonrespondents. There was no increase in crude (odds ratio, 0.99; 95% confidence interval, 0.85-1.17) or age-adjusted risk of crashes for men with a medical condition in the entire sample of subjects (N = 5024). Among respondents to the mailed questionnaire only, men with a medical condition showed no increased crude risk of crashes (odds ratio, 0.99; 95% confidence interval, 0.76-1.27); no difference was observed after adjustment for age, mileage driven, driver behaviors, and sociodemographic characteristics (odds ratio, 0.91; 95% confidence interval, 0.64-1.31). CONCLUSIONS: Unlike previous studies, the risk estimate was derived from a population-based sample of drivers and adjusted for age, mileage driven, driver behaviors, and sociodemographic characteristics in multivariate analyses. The adjusted estimates failed to show an increased risk of motor vehicle crashes for drivers with a medical condition.

Accidents, Traffic↗
PubMedDate not supplied

The Kahnawake Schools Diabetes Prevention Project: intervention, evaluation, and baseline results of a diabetes primary prevention program with a native community in Canada.

OBJECTIVES: Kahnawake Schools Diabetes Prevention Project is a 3-year community-based, primary prevention program for non-insulin-dependent diabetes mellitus in a Mohawk community near Montreal, Canada. Objectives are to improve healthy eating and encourage more physical activity among elementary school children. METHODS: Intervention incorporates behavior change theory, Native learning styles, the Ottawa Charter for Health Promotion, and a health promotion planning model. Evaluation uses a mixed longitudinal and cross-sectional design to measure obesity, fitness, eating habits, and physical activity of elementary school children in the experimental and comparison communities. Intermediate variables are self-efficacy and perceived parental support. Process evaluation provides feedback to the intervention. RESULTS: During 3 years, 63 distinct interventions that included a Health Education Program reinforced by school events, a new Community Advisory Board, a recreation path, and community-based activities promoting healthy lifestyles were implemented. Baseline consent rates were 87 and 71% in the experimental and comparison schools. As expected, anthropometric data increase with age. Between 9 and 10 years there are increased weight, height, BMI, and skinfold thicknesses; decreased fitness; and increased television watching. CONCLUSIONS: Implementing a Native community-based diabetes prevention program is feasible through participatory research that incorporates Native culture and local expertise.

Child↗