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Biomedical subjects

A Demers

Publications and source records attributed to A Demers.

18 recordsLinked to original sources
PubMed2002

CD36 mediates the cardiovascular action of growth hormone-releasing peptides in the heart.

Growth hormone-releasing peptides (GHRPs) are known as potent growth hormone secretagogues whose actions are mediated by the ghrelin receptor, a G protein-coupled receptor cloned from pituitary libraries. Hexarelin, a hexapeptide of the GHRP family, has reported cardiovascular activity. To identify the molecular target mediating this activity, rat cardiac membranes were labeled with a radioactive photoactivatable derivative of hexarelin and purified using lectin affinity chromatography and preparative gel electrophoresis. A binding protein of M(r) 84 000 was identified. The N-terminal sequence determination of the deglycosylated protein was identical to rat CD36, a multifunctional glycoprotein, which was expressed in cardiomyocytes and microvascular endothelial cells. Activation of CD36 in perfused hearts by hexarelin was shown to elicit an increase in coronary perfusion pressure in a dose-dependent manner. This effect was lacking in hearts from CD36-null mice and hearts from spontaneous hypertensive rats genetically deficient in CD36. The coronary vasoconstrictive response correlated with expression of CD36 as assessed by immunoblotting and covalent binding with hexarelin. These data suggest that CD36 may mediate the coronary vasospasm seen in hypercholesterolemia and atherosclerosis.

Animals↗
PubMed2001

Short polyglutamine tracts in the androgen receptor are protective against breast cancer in the general population.

We studied the association of breast cancer with the polymorphic polyglutamine repeat of the androgen receptor (AR) in 255 incident cases of breast cancer and 461 matched controls from the Quebec City metropolitan area. Women for whom the sum of both of the AR (CAG)n-repeats alleles is 39 or less (short-allele AR genotypes) have one-half the risk of breast cancer compared with women for whom the sum of AR (CAG)n-repeats is 40 or more [odds ratio (OR), 0.5; 95% confidence interval (CI), 0.3-0.83; P = 0.007]. This association is stronger in postmenopausal women (180 cases, 297 controls; OR, 0.36; 95% CI, 0.19-0.7; P = 0.003). We also observed an interaction between the type of menopause (natural versus surgical) and the AR genotype on breast cancer risk. Alternately, when subjects were grouped according to their (CAG)n-repeat genotype [homozygous for short alleles (CAG)n < or = 20; other genotypes ("long allele")], results were similar (OR. 0.5; 95% CI, 0.27-0.82; P = 0.007). Thus, women with short-alleles AR genotypes appear to be protected against breast cancer. Short-alleles AR genotypes were observed in 16% of the general population as represented by the control group. Short polyglutamine repeats in the AR protein have been reported to be associated with an increase in the capacity of the receptor to activate transcription of reporter genes in vitro. Furthermore, androgens have been previously shown to inhibit in vitro the growth of breast cancer cell lines. This suggests that differences in the number of polyglutamines in the AR protein may influence individual risk of breast cancer, especially in postmenopausal women, and that this apparent protection could be the consequence of an increased response/sensitivity to androgens.

Breast Neoplasms↗
PubMed2001

The prevalence of elevated psychological distress among Canadian undergraduates: findings from the 1998 Canadian Campus Survey.

For a study of elevated psychological distress, the authors used data based on a national probability sample of 7,800 Canadian undergraduate students from 16 universities. They used the 12-item General Health Questionnaire to assess mental health. Thirty percent of the students in the sample reported elevated psychological distress, which varied significantly according to sex, region, year of study, and recreational and academic orientation. Rates of elevated distress were significantly higher among the students than among the general population in Canada.

Adolescent↗
PubMed2000

Risk and aggressiveness of breast cancer in relation to plasma organochlorine concentrations.

Several organochlorines identified as "hormone mimics" were proposed as possible risk factors for breast cancer. We conducted a case-control study to assess breast cancer risk and disease aggressiveness in relation to plasma concentrations of several organochlorine compounds. Plasma lipid concentrations of 11 chlorinated pesticides and 14 polychlorinated biphenyl congeners were measured in 315 women newly diagnosed with breast cancer, 219 hospital-based controls, and 307 population controls from the Quebec City area (Canada). Concentrations of hormonally active organochlorines or their surrogates were compared between cases and controls as well as between groups of cases defined according to tumor size and axillary-lymph-node involvement. We found similar levels of organochlorines in cases and controls and no relationship between the relative risk of breast cancer and organochlorine exposure. However, the probability of lymph-node invasion among cases increased with exposure to 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene [p,p'-DDE; odds ratio, 2.54; 95% confidence interval (CI), 1.20-5.35; between the highest and the lowest tertiles]. Furthermore, p,p'-DDE exposure was associated with a dose-related increased relative risk of exhibiting both lymph-node involvement and a large tumor. Indeed odds ratio raised to 2.33 (95% CI, 0.94-5.77) for the second tertile relative to the first tertile and reached 3.51 (95% CI, 1.41-8.73) for the third tertile relative to the first tertile. Similar associations were noted with beta-hexachlorocyclohexane, oxychlordane, and transnonachlor. We conclude that exposure to persistent, hormonally active organochlorines during adulthood is not associated with breast cancer risk. The possibility that some organochlorines and especially p,p'-DDE may increase breast cancer aggressiveness deserves further attention.

Adult↗
PubMed1999

The validity of the CAGE scale to screen for heavy drinking and drinking problems in a general population survey.

BACKGROUND: The CAGE scale is a short test developed in the 1970s to screen for alcoholism or covert drinking problems. The reliability and validity of the scale has been demonstrated in the majority of studies conducted in clinical settings, but the validity of the scale in general population surveys has not yet been shown conclusively. AIMS: The goal of this study was to assess the criterion validity of the CAGE scale in a general population survey. METHOD: Data from a large general health survey conducted in 1992 in the province of Quebec (Canada) (N = 23,564) were used to define various measures of heavy drinking and drinking problems and to calculate, for male and female drinkers separately, standard measures of sensitivity, specificity and positive predictive value at different cutoff scores on the CAGE. FINDINGS: With respect to both male and female drinkers, with all operational definitions of heavy drinking and useful cutoff scores on the CAGE, the scale was shown to be unable to discriminate between heavy drinkers and non-heavy drinkers. Prevalence of drinking problems among CAGE positive drinkers was also very low. CONCLUSION: These results do not support the use of the CAGE as a screening tool for heavy drinking and drinking problems in a general population survey or as a tool to estimate the prevalence of drinking problems in the population.

Adolescent↗
PubMed1999

Concentration of organochlorines in human brain, liver, and adipose tissue autopsy samples from Greenland.

Organochlorines are persistent lipophilic compounds that accumulate in Inuit people living in circumpolar countries. Organochlorines accumulate as a result of the Inuits' large consumption of sea mammal fat; however, available data are limited to blood lipids, milk fat, and adipose tissue. We report results of organochlorine determination in liver, brain, omental fat, and subcutaneous abdominal fat samples collected from deceased Greenlanders between 1992 and 1994. Eleven chlorinated pesticides and 14 polychlorinated biphenyl congeners were measured in tissue lipid extracts by high-resolution gas chromatography with electron capture detection. Mean concentrations of polychlorinated biphenyls, 2, 2'-bis(4-chlorophenyl)-1,1-dichloroethylene, ss-hexachlorocyclohexane, hexachlorobenzene, mirex, trans-nonachlor, and oxychlordane in adipose tissue samples from Greenlanders were 3-34-fold higher than those measured using the same analytical method in samples from Canadians in Quebec City, Quebec. Brain lipids contained lower concentrations of all organochlorines than lipids extracted from other tissues. Organochlorine residue levels in lipid extracts from liver, omental fat, and subcutaneous abdominal fat samples were similar, with the exception of ss-hexachlorocyclohexane, which reached a greater concentration in liver lipids than in lipids from both adipose tissues (4-fold; p < 0. 05). Comparisons with available international data on adipose tissue levels reveal that the organochlorine body burden in the Inuit population of Greenland is presently among the highest resulting from environmental exposure.

Adipose Tissue↗
PubMed1999

Wives' convergence with their husbands' alcohol use: social conditions as mediators.

OBJECTIVE: This study examines, in a general population, how the association of wives' alcohol use with their husbands' is mediated by social conditions such as working and child-rearing roles, age, marital happiness and socioeconomic levels. METHOD: Data come from the Québec Health and Social Survey 1992-93. The sample comprised 6,582 couples; 3,872 couples after weighting. Regression analyses assessed the contribution of husbands' drinking to wives' drinking, independently, as well as in interaction with social conditions. Frequency of drinking in general and frequency of five or more drinks per occasion (5+) were analyzed. RESULTS: Wives' drinking is positively related to their husbands' drinking, both in terms of frequency of drinking and, to a lesser degree, of frequency of 5+. The drinking frequency association is not modified by working or child-rearing roles, nor by age, but is more marked for couples of higher socioeconomic levels and for wives happy with marital life. The frequency of 5+ association is not modified by marital happiness or by wives' working roles, but is more marked for couples of higher socioeconomic levels, for couples with a child at home and for younger women. CONCLUSIONS: This study highlights the contribution of social factors to the association of wives' drinking with their husbands' and suggests that these social factors operate through structuring marital drinking interactions. Further research is needed to clarify the complex social processes that mediate the spousal drinking association.

Adolescent↗
PubMed1997

Solitary drinking: a risk factor for alcohol-related problems?

This paper investigates whether solitary drinking is a risk factor for alcohol-related problems using data from a general population of drinkers in Montréal, Canada. Three indicators of solitary drinking were used: (1) having had a drink alone; (2) frequency of solitary drinking; and (3) having had five drinks or more in a solitary setting. Among the 2015 respondent drinkers of a telephone survey, 31% reported drinking alone, of whom 27% did so more than once a week, and 17% had had five drinks or more alone at least once. Problems with family or social relationships, physical health, work, budget, physical security and happiness or view of life, self-reported as being alcohol-related, were measured by seven binary items. Strong positive associations were found at the univariate level between overall alcohol-related problems and both solitary drinking and having had five or more drinks alone, whereas frequency of solitary drinking had no effect. Only the relationship with having five or more drinks alone remained statistically significant in logistic regressions controlling for potential confounders. No evidence was found that solitary drinking per se is a risk factor for alcohol-related problems unless large quantities of alcohol are involved.

Adolescent↗
PubMed1996

Changing society, changing drinking: solitary drinking as a non-pathological behaviour.

This study describes solitary drinking as it appears in a general population. The data are derived from a telephone survey carried out in April 1993 on a representative sample of 2015 adult drinkers from the Montréal metropolitan area. Thirty-one percent of the respondents (n = 633) reported drinking without being in the company of other people. First, solitary drinking is described according to drinking contexts and drinking patterns. Secondly, a comparison of solitary drinkers with those who did not report this behaviour is presented according to socio-demographic characteristics, social representations of drinking and overall drinking patterns. Finally, a logistic regression analysis is performed to identify the main characteristics of the drinkers associated with solitary drinking. The results show that solitary drinking occurs mainly at home, at the end of the day, to accompany a meal, to mark a transition between work and leisure or to accompany a rest time. The quantity involved in solitary drinking is generally moderate. The results also show that solitary drinking is associated with gender, living alone, employment status, tension-reduction and harmful representations of drinking. However, the main predictor of solitary drinking is overall drinking frequency, indicating the constituent place of alcohol in solitary drinkers' life-style.

Adult↗
PubMed1996

When anthropology meets epidemiology: using social representations to predict drinking patterns.

Based on a sample of 2,015 adult drinkers from the Montreal metropolitan area (Quebec, Canada), this study investigates the relationship between eight social representations of drinking (i.e., compensatory, convivial, relaxing, disinhibitory, harmful, sexually enhancing, conventional, socially enabling) and drinking measures (QF Index, drinking frequency, and maximum number of drinks on one occasion) according to age and sex. The representations explain up to 34% of the variance in drinking measures. Representations differed in the strength of their relation to drinking measures and in population prevalence. Strength of relation to drinking and prevalence rates were relatively independent. Representations were generally more strongly endorsed by men than women, although they were related in the same way to drinking behaviors. Representations were also more strongly endorsed by younger than by older respondents, and they related differently to drinking in each age group. The implications of these results for prevention are discussed.

Adolescent↗
PubMed1992

Increased avidity of mutant IgM antibodies caused by the absence of COOH-terminal glycosylation of the mu H chain.

We have previously described the isolation of two hybridoma variants secreting higher avidity IgM (D5 and 7F5), starting from the E11 hybridoma cell line, which produces an antibody specific for the A Ag of the ABO blood group system. In order to explain at the molecular level this increased reactivity, cDNA encoding the H and L chains of the E11, D5, and 7F5 mAb were cloned and sequenced. Comparison of the nucleotide sequences showed a single point mutation in each of the two mAb produced by the hybridoma variants. The mutations were both located in the H chain C region and caused a Ser to Phe substitution at position 565 in the D5 mAb and a Asn to Tyr substitution at position 563 in the 7F5 mAb. Both substitutions modified the consensus glycosylation sequence (Asn-X-Ser/Thr) located in the tail piece of the secretory mu-chain. The absence of glycosylation at this site was confirmed by CNBr cleavage of the [14C]mannose-labeled mAb. The two single point mutations were solely responsible for the increased avidity of the antibodies, as confirmed by site-directed mutagenesis of the E11 mu-chain and serologic analysis of the mutated E11 antibodies. We conclude that the absence of glycosylation at Asn 563 is responsible for the increased avidity of the mutant, possibly by altering the quaternary structure of the IgM polymer. To our knowledge, this is the first report that point mutations in the H chain C region can influence the reactivity of IgM mAb.

Amino Acid Sequence↗
PubMed1992

[Support provided by third parties and the reaction of close female caregivers in the care of elderly persons with loss of autonomy].

This article is about the relation between, on the one hand, support provided by third parties and, on the other, the burden and the depression experienced by the main female supporters who care for the elderly suffering from physical or cognitive problems. The authors examine the hypothesis that social support is not homogeneous across the board and that the different types of support are likely to have different effects on elders with adverse reactions to the caring process. Data originates from a study that was conducted in the Montréal area in 1990 with 159 female supporters living with an elder requiring care who requested support services from formal and informal networks. Hierarchical regression analyses show that the variables in connection with care dispensed by the network play a limited role in attempting to explain the depression and burden levels. Furthermore, these analyses confirm the hypothesis of the variables' narrow range of influence.

Activities of Daily Living↗
PubMed1990

Light scattering studies of the effect of Ca2+ on the structure of porcine submaxillary mucin.

The effects of calcium ions on the solution properties of porcine submaxillary mucin (PSM) have been investigated by static and dynamic light scattering. The weight average molecular weights of PSM fractions are unaffected by the addition of up to 0.5M CaCl2: these data are within experimental error of those for solutions in 0.1M NaCl. The distribution of relaxation frequencies derived from the dynamic data shows the existence of two distinct relaxation modes. The average relaxation times have been interpreted to yield the z-average translational diffusion coefficient and the longest intramolecular relaxation time tau1. A plot of tau1 vs the mean value of 1/Rh-3z is linear, and consistent with plots of such data recorded for PSM in 0.1m NaCl and 6M GdnHCl solutions. However, the tau values and the associated results for the mean value of R-1h-1z in 0.5M CaCl2 are smaller than those determined in 0.1M NaCl. This suggests that the conformation of PSM in CaCl2 solution is more contracted than those in the other two solvents. These results are consistent with the compact packaging of mucin in the secretary granules that have elevated Ca2+ levels.

Animals↗
PubMed1989

Dynamic light scattering studies of porcine submaxillary mucin fractions in dilute solution at intermediate scattering vectors.

We report dynamic light scattering measurements over a wide range of scattering vectors for fractionated samples of porcine submaxillary mucin (PSM) glycoproteins in two different solvents: 0.1M NaCl, and 6M GdnHCl. The relaxation spectrum has been successfully resolved into a slow mode corresponding to pure translational diffusion and a fast mode containing information on the relaxation times for intramolecular motion. Analysis of the slow mode permits a light scattering evaluation of the polydispersity of these high molecular weight mucin glycoprotein fractions. Determination of the longest intramolecular relaxation times tau 1 shows that these are much longer for the PSM fractions in 0.1M NaCl compared to 6M GdnHCl. These data are consistent with earlier studies showing that the chain conformation is the same in both solvents, but that in 0.1M NaCl, the PSM glycoprotein undergoes a self-association process that is end-to-end in nature. Since the tau 1 value is intimately related to the viscoelastic behavior of PSM solutions and gels, it is interesting to speculate that the end-to-end association process may be physiologically important.

Animals↗
PubMedDate not supplied

Integration of midwives into the Quebec health care system. L'Equipe d'Evaluation des Projets-Pilotes Sages-Femmes.

This paper reports on one aspect of the evaluation of the midwifery pilot projects in Quebec: the identification of the professional and organizational factors, as well as the mode of integrating midwives into the maternity care system, that would promote the best outcomes and the autonomy of midwives. The research strategy involved a multiple-case study, in which each midwifery pilot project represented a case. Based on a qualitative approach, the study employed various sources of data: individual interviews and focus groups with key informants, site observations and analyses of written documents. Results show that midwives were poorly integrated into the health care system during the evaluation. Four main reasons were identified: lack of knowledge about the practice of midwifery on the part of other health care providers; deficiencies in the legal and organizational structure of the pilot projects; competition over professional territories; and gaps between the midwives' and other providers' professional cultures. Recommendations are provided to facilitate the integration of midwives into the health care system.

Attitude of Health Personnel↗
PubMedDate not supplied

[Evaluation of results of a nutritional marketing intervention in Montreal restaurants].

This article reviews two major questions examined in conjunction with the evaluation of the feasibility of a nutritional marketing program in restaurants. The first question focuses on the acceptance by restaurateurs of this type of initiative and the second, on the receptiveness of consumers. The evaluation allows us to render a positive judgement regarding the project while recognizing its limitations. The evaluation also points to a number of ways in which the program should be changed if it is expanded.

Advertising↗