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N Leduc

Publications and source records attributed to N Leduc.

16 recordsLinked to original sources
PubMed2006

Variations in sucrose and ABA concentrations are concomitant with heteroblastic leaf shape changes in a rhythmically growing species (Quercus robur).

In rhythmically growing woody species such as common oak (Quercus robur L.), stem growth is discontinuous and a bud forms at regular intervals at the shoot apex. These buds are composed of different types of leaves: laminate, aborted lamina and scale. The change in heteroblastic leaf shape from laminate to aborted lamina leaves is regarded as one of the events marking shoot growth arrest. To better understand the determinism of heteroblastic leaf shape change and thus, of rhythmicity, we studied morphogenetic events during the early days of the second flush of growth in oak, as well as changes in sucrose metabolism and abscisic acid (ABA) concentrations in control plants expressing the heteroblastic leaf shape change and in defoliated plants showing no heteroblastic leaf shape change and producing only laminate leaves. In control plants, the leaf shape change was underway on Day 5 of the second flush with the differentiation of the first two aborted lamina leaves. Sucrose concentration in the apices of control plants decreased between Days 3 and 5 during differentiation of the aborted lamina leaves. An inverse pattern was observed in defoliated plants, suggesting that sucrose acts as a signal triggering heteroblastic leaf shape changes. During the same period, acid cell wall invertase activity was high in young stem and laminate leaves of control plants, whereas the activity remained constant and low in the apices. If the laminate leaves were removed, the increase in apical sucrose concentration was proportionally higher than the decrease in apical acid vacuolar invertase activity, suggesting that, in the absence of young leaves, sucrose is imported to the apex. The sucrose concentration in the apex is therefore likely to be affected by trophic competition with the expanding laminate leaves. The decrease in apex sucrose concentration may be one of the mechanisms driving heteroblastic leaf shape change. Differentiation of aborted lamina leaves was followed by a decrease in the organogenic activity of the shoot apical meristem (SAM) between Days 7 and 9. High concentrations of ABA are associated with differentiation of aborted lamina and scale leaves and with low SAM organogenic activity. Shoot apical meristem organogenic activity remained high and ABA concentration in the apex remained low in defoliated plants producing only photosynthetic leaves. These results suggest that (1) ABA is involved in the gradual conversion of embryonic leaves to abnormal leaves, thereby regulating heteroblastic leaf shape changes and (2) changes in ABA concentration influence the intensity of SAM organogenic activity. Heteroblastic development and therefore rhythmic growth could be the result of competition between apices and laminate leaves, with competition first involving sucrose and thereafter ABA.

Abscisic Acid↗
PubMed2002

[Prior use of a telephone-nursing triage service by patients of emergency services].

OBJECTIVES: A province-wide telephone-nursing triage service was implemented in Quebec, Canada, in order, among other objectives, to decrease overcrowding in hospital emergency rooms. This study analyses prior use of Info-Sante CLSC telephone service by patients of emergency services. METHODS: Structured interviews were conducted with 850 patients of a general hospital emergency room and of walk-in medical clinics. Patients were recruited while waiting to see the physician between 8h and 23 h, 7 days a week, from November 1997 to June 1998. Information was collected on knowledge and use of the telephone-nursing triage service, health problem and perceived health status, information-seeking behaviour on health services, utilisation habits, social support, and socio-demographic characteristics. Interval estimates and multiple logistic regressions were performed. RESULTS: Of the patients who were aware of this service, 17,4% (CI(95)=0,14 - 0,20) had used it prior to their medical visit. Among these, 85,1% had received a recommendation to consult a doctor. Among the users who were at the hospital emergency room at the time of the study, 56,4% were advised to consult a walk-in clinic or a CLSC, 28,2% their family doctor and only 12,8% a hospital emergency room. The probability of prior recourse to the telephone nursing service is influenced significantly by the duration of the health problem (2-4 days versus<2 days: OR(adjusted)=2,03), new health problem (OR(adjusted)=1,98) and by the frequenting of walk-in clinics rather than hospital emergency rooms (OR(adjusted)=0,31). CONCLUSION: Despite a heightened awareness of the telephone-nursing triage service, few users of emergency services make use of it and, when they do, follow rather loosely the recommendation towards the type of service judged appropriate for their needs.

Adult↗
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

What factors determine whether individuals found to have hypercholesterolaemia at mass screening accept advice to visit their physician.

OBJECTIVE: This study aims to identify the determinants of compliance with the recommendation to visit a physician for advice which was given to individuals whose cholesterolemia was > 6.2 mmol/l at mass screening for risk factors of cardiovascular diseases. METHODS: Data were collected from 1144 adults found to be hypercholesterolemic during a screening programme in 54 work sites and 29 public areas and contacted by phone two to six months later. Based on the Health Belief Model, perceived seriousness, perceived self-efficacy, and cues to action were measured. Potential determinants of compliance to the recommendation were examined using multivariate analyses. RESULTS: Mean compliance was 58.6%. For the perceived seriousness dimension of the Health Belief Model, personal history of CVD or risk factors, and prior awareness of cholesterol levels were important determinants. Those already treated for hypercholesterolemia comply twice as much as those who were aware and untreated. Among cues to action, higher cholesterol levels and hypertension are associated with greater compliance; however, smokers were less likely to comply. The dimension of perceived self-efficacy, as measured by ease of access to health services and prior success in eating habit modification, is also associated with compliance to the recommendation. Compliance increases significantly with age. For those previously aware of their elevated cholesterol level, variables representing perceived self-efficacy were no longer determinants. For those previously unaware of their elevated cholesterol level, variables representing CVD perceived threat do not influence compliance. CONCLUSION: The Health Belief Model appears to be an appropriate framework to the determinants of compliance with the recommendation to visit a doctor during mass screening.

Adult↗
PubMed1998

Compliance of frail elderly with health services prescribed at discharge from an acute-care geriatric ward.

OBJECTIVES: A model of compliance by frail elderly with prescribed healthcare services was developed and tested. The discrepancy between primary care, geriatric and community health center (CLSC) services prescribed at discharge after comprehensive geriatric evaluation and treatment was measured, as were those services actually used during a 6-week interval (compliance). In this model, compliance was directly related to elders' intention to adhere to prescribed services, but this relationship was modified by organizational factors, reinforcing factors, and changes in health status during the observation period. Intention to adhere resulted from individual and reinforcing factors existing before discharge. METHODS: This model was tested on 211 patients discharged to community settings from an acute-care hospital geriatrics ward. Information was obtained through interviews with the patients or care givers and from hospital, outpatient, and local community health center charts. RESULTS: On average, patients used 56.9% of services prescribed; 13% of patients did not use any of the services prescribed for them, whereas 22% used all the services prescribed. Intention to adhere was influenced by patients' perception of the benefits of prescribed services and by their perception of the ease of access to transportation. Intention itself was not found to be an important determinant of overall compliance. Among organizational factors, having the ward staff make a follow-up appointment with the patients' family doctor and with the geriatric clinic before discharge and communication with the local community health center increased overall compliance. Moreover, patients who perceived they had access to transportation and to an accompanying person were more likely to comply. CONCLUSIONS: The results suggest that when discharging patients to the community, steps taken for them by the discharging healthcare providers will improve compliance.

Aged↗
PubMed1998

[Health promotion for immigrant women in Quebec].

Over the past fifteen years, the Canadian population has undergone increasing cultural diversification. Many researchers have investigated the role of culture with respect to social and health services. Most studies confirm the fact that increased cultural diversification related to immigration challenges the public health system in many ways. Certain groups, such as economically challenged immigrant women, may pose even greater problems to the health system. While these individuals are in relatively good health upon arrival to Canada, there is a need to ensure that adequate health promotion as well as disease prevention strategies are instituted. It is important to examine the concepts of health promotion and disease prevention through a cultural perspective. Little research has been done in this area. Concepts of promotion and prevention as they are understood by immigrants may not always coincide with North American or European definitions. Therefore, it is essential to consider life conditions that surround potential health promotion and prevention behaviors of immigrants. Empowerment, economic integration and acculturation are among the many factors that need to be taken into account when studying immigrants' health promotion behavior. Here, we present a critical analysis of current knowledge in this field. This is followed by research recommendations aimed at facilitating the development of health promotion and prevention strategies that are appropriate to the needs of Canadian, and more specifically of immigrant women in Québec.

Acculturation↗
PubMed1997

First evidence of a calcium transient in flowering plants at fertilization.

We report here the first evidence of a transient elevation of free cytosolic Ca2+ following fusion of sperm and egg cell in a flowering plant by the use of an in vitro fertilization system recently developed in maize. Imaging changes in cytosolic Ca2+ at fertilization was undertaken by egg cell loading with the fluorescent Ca2+ indicator dye fluo-3 under controlled physiological conditions. The gamete adhesion step did not induce any cytosolic Ca2+ variation in the egg cell, whereas the fusion step triggered a transient cytosolic Ca2+ rise in the fertilized egg cell, lasting several minutes. This rise occurred after the establishment of gamete cytoplasm continuity. Through these observations, we open the way to the identification of the early signals induced by fertilization in flowering plants that give rise to the calcium transient and to investigations of the role of Ca2+ during egg activation and early zygote development in plants, as has been reported for other better characterized animal and algae systems.

Aniline Compounds↗
PubMed1996

Isolated maize zygotes mimic in vivo embryonic development and express microinjected genes when cultured in vitro.

We established conditions for the regeneration of natural maize zygotes isolated from pollinated plants with the goal of investigating the molecular control of early embryogenesis in higher plants. Viable zygotes were excised from embryo sacs by minimal enzymatic digestion and microdissection. Viable zygotes transferred to coculture with androgenic microspores from barley developed into embryo-like structures in 61% of the cases. No development was observed when zygotes were cultured in the presence of maize anthers undergoing androgenetic embryogenesis. Zygote-derived embryo-like structures regenerated into fertile plants through secondary embryogenesis when transferred to solid medium. The first zygotic division was asymmetrical and bipolar structures similar to pretransitional embryos observed in planta were later produced as observed using light and electron microscopy. Conditions for efficient microinjection of DNA into zygotes were established. Calcofluor and PATAG staining of zygotes showed that cell wall regeneration occurred as early as 20 min after enzymatic isolation and that after 2 hr, each zygote was bordered with cell wall material. Through quantitative microphotometry, DNA synthesis during the first cell cycle of the zygote was shown to occur between isolation and 12 hr of culture. Microinjection of two types of reporter genes (GUS gene and anthocyanin regulatory genes) demonstrates transient expression in plant zygotes. On average, 3.5% of microinjected zygotes showed transgenic expression. Reporter gene expression was observed in zygotes at different time points of their first cell cycle.

Cell Cycle↗
PubMed1995

Prosthetic relining and dietary counselling in elderly women.

A reduced consumption of hard-textured fibrous foods may promote the development of digestive disturbances in more susceptible elderly people who wear prostheses having deficient masticatory function. The purpose of this study was to evaluate the effects of a program combining denture relining and dietary counselling on the masticatory performance, fibre intake, and prevalence of digestive symptoms in elderly women with low chewing efficiency. This program was provided to 55 women between 55 and 74 years of age. Chewing ability was assessed quantitatively with the Swallowing Threshold Test Index (STTI), and qualitatively according to the participants' experience in chewing five specific foods. Nutritional data were collected using a food frequency questionnaire. The mean value of the STTI was significantly increased at three weeks and at six to nine months after completion of relining by 37 and 31 per cent, respectively. Subjects included one more food in their diet at the end of the six- to nine-month period only. Fibre intake from vegetables was significantly increased by 18 per cent, while colonic and gastrointestinal symptoms were both reduced. Prosthetic relining increased the masticatory performance of elderly women, but not to a functional level. In addition, dietary counselling stimulated subjects to eat foods that had previously been avoided. These observations suggest that the improvement of chewing efficiency, combined with dietary counselling, could reduce the presence of digestive symptoms.

Aged↗
PubMed1993

Organizational and environmental determinants of the performance of public health units.

In the wake of the reform of the Quebec health care system in the early 1970s, thirty-two public health units (DSCs) were created. They were administratively and geographically integrated into short-term care hospitals throughout the province. This study aimed at determining: (1) the influence of environmental and organizational factors on the way in which those public health units carried out their mandate; (2) the influence of these same factors on their performance in terms of level of innovation and in terms of the fulfillment of their mandate as assessed by their main clients; and (3) the influence of their activities on their performance. Our results show that the most innovative units appear to be those that have directed a large part of their efforts toward research and that have maintained close ties with other institutions and agencies. The public health units main clients differ however on their perception of the DSCs' performance.

Community Health Services↗
PubMed1990

Content and methods of studies on the prevention and treatment of mental disorders in selected psychiatric journals.

Studies on psychiatric treatments published in 1986 were reviewed in five major psychiatric journals (Am. J. Psychiatry, Can. J. Psychiatry, Arch. Gen. Psychiatry, Am. J. Orthopsychiatry and Am. Acad. Child Psychiatry). Articles on prevention and treatment represent only 27% of the total of titles (194 out of 731 articles). The studies reviewed focus mostly on the treatment of adults, on psychoses, on the short term effect of treatment and on the effect of treatment rather than its process. Almost no information is published on the evaluation of the process or on the cost of treatment. Studies are for the most part original, but they tend to be studies without controls rather than randomized or non-randomized controlled trials. Interpretation of results rely essentially on statistical significance and almost no attention is paid to the evaluation of impact, in epidemiological terms, of the cause-effect relationship and to the clinical relevance of observed differences. Psychiatrists who read only a few major journals of psychiatry should get more information on therapeutic and preventive interventions in comparison to other components of clinical work and to clinical course of disease.

Humans↗
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↗
PubMedDate not supplied

[Emigration of Quebec physicians: motivation for departure and return].

Since the 80's, outmigration of physicians from Quebec is steadily increasing. About 46 percent of outmigrating doctors explain their move by factors related to their occupational life (higher income, greater opportunity in the academic career, larger amount of resources devoted to the health care system). Nearly 40 percent relate their decision to personal factors (greater job opportunity for their wife/husband, quality of family life...). The factors linked to the context of the receiving place (political climate, linguistic regulations, income tax level...) play a minor role on the migration decision. As concerns the returning physicians, 80 percent explain their decision by personal factors. The factors linked to the occupational life have a lower role. It appears therefore that doctor outmigration from Quebec is not directly determined by manpower policies adopted by the Province during the last two decades, except the policies directly linked to the income level of professionals.

Adult↗
PubMedDate not supplied

[Beyond the statistics: why are Quebec physicians emigrating?].

During the period 1986-1999, about 16% of the annual average number of active physicians in Quebec have left for the US or an other Canadian province. The absolute number was 2367. During the same period, 661 would have returned to Quebec. The majority of the outmigrating doctors were graduated from the anglophone university of the Province (although 44 percent are francophone) whereas the majority of the returning doctors were graduated from the 3 francophone universities of the Province. As a matter of fact, 78 percent of the returning doctors are francophone. The migration decision is equally linked to post-graduate training and occupational opportunities and job satisfaction. This feature should be related to an other: those who have returned to Quebec have had a geographic and occupational mobility level far lower than those who have not returned. Finally, it is noteworthy that there are significant differences between the doctors emigrating to the US and their colleagues going to an other Canadian province.

Adult↗
PubMedDate not supplied

[Innovation in the Quebec's community health departments].

Following the reform of the health care system in Quebec at the beginning of the 1970s, 32 Community Health Departments (départements de santé communautaire or DSC) were created; these new organizations were administratively and physically integrated into 32 acute care hospitals throughout the province. Our study investigates to what extent variations in the implementation of DSCs and in the way they have fulfilled their mandate influence the degree of innovation of their practices. The results show that DSCs devoting greater efforts to research activities and to their relationships with other health care establishments and agencies achieve a higher level of innovation in their practices.

Community Health Services↗