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Biomedical subjects

S B Harris

Publications and source records attributed to S B Harris.

At least 73 records · Page 4Linked to original sources
PubMed1998

Absence of association between genetic variation of the beta 3-adrenergic receptor and metabolic phenotypes in Oji-Cree.

OBJECTIVE: To assess the association between the common missense variant, Y64R, in the gene encoding the beta 3-adrenergic receptor, ADRB3, and intermediate phenotypes related to obesity and NIDDM in Canadian Oji-Cree. RESEARCH DESIGN AND METHODS: We determined genotypes of the ADRB3 Y64R polymorphism in 508 clinically and biochemically well-characterized adult Oji-Cree, of whom 115 had NIDDM. We tested for associations with multivariate analysis of variance. RESULTS: We found the ADRB3 R64 allele frequency to be 0.40 in this population, which is the highest yet observed in a human population. Furthermore, 15% of subjects were R64/R64 homozygotes, compared with a virtual absence of homozygotes in European study samples. However, we found no statistically significant associations of the ADRB3 Y64R genotype either with the presence of NIDDM, with indexes of obesity, or with intermediate quantitative biochemical traits related to NIDDM. CONCLUSIONS: Despite the very high frequency of the ADRB3 R64 allele in this sample of aboriginal people, it was not associated with any metabolic phenotype. This suggests that the ADRB3 R64 allele is probably not a major determinant of obesity or NIDDM in these aboriginal Canadians.

Adipose Tissue↗
PubMed1998

Disease patterns among Canadian aboriginal children. Study in a remote rural setting.

OBJECTIVE: To describe disease patterns among children in an isolated aboriginal community, and to compare them with patterns found among other aboriginal and non-aboriginal Canadian children. DESIGN: Retrospective review of logbooks and patient charts extracted from nursing station records for all visits to the community's nursing station between April 1, 1990, and March 31, 1991. SETTING: An isolated aboriginal community located in northwestern Ontario. PARTICIPANTS: All aboriginal children younger than 5 years. MAIN OUTCOME MEASURES: Disease-specific incidence per 100 person-years by age, sex, and season. RESULTS: Upper and lower respiratory tract infections, skin conditions, otitis media, and chickenpox were the leading causes of illness. Except for chickenpox, these illnesses occurred at a significantly higher rate among infants than among children 1 to 4 years old. No important differences were found by sex for any condition, except asthma where boys predominated. Autumn and winter seasonal patterns were most evident for respiratory tract infections. The rate of illness for most conditions was higher than that reported among other aboriginal and non-aboriginal Canadian children. CONCLUSIONS: The illnesses most frequently seen in these children are respiratory tract infections and skin conditions. Etiologic factors are likely to be related to multiple interacting forces (both environmental and genetic) and require further investigation.

Age Distribution↗
PubMed1997

Low dietary fiber and high protein intakes associated with newly diagnosed diabetes in a remote aboriginal community.

The high prevalence of diabetes mellitus in North American aboriginal populations may be due to recent changes in lifestyle, including the adoption of a high-fat, low-fiber diet. To determine whether fat or fiber intakes were associated with new cases of diabetes, we studied 72% (728/1018) of residents aged > 9 y from a remote aboriginal community in northern Ontario using the 75-g oral-glucose-tolerance test and 24-h dietary recall. The mean fat intake of this population (36% of energy) was typical for North America, but fiber intake (1.2 g/MJ) was very low. Logistic-regression analysis, adjusted for age, sex, and body mass index, showed that a 1-SD increase in fiber intake reduced the risk of having diabetes by 39% (P = 0.026) whereas the same increase in protein intake increased the risk by 38% (P = 0.027). There was no significant effect of energy, fat, starch, or simple sugars. These data support Trowell's original dietary-fiber hypothesis that "... dietary fiber depleted starchy foods are conducive to the development of diabetes mellitus in susceptible human genotypes."

Adolescent↗
PubMed1997

Common genomic variation in the APOC3 promoter associated with variation in plasma lipoproteins.

We hypothesized that common genomic variation that affected the expression and/or function of the products of the APOC3, APOE, FABP2, and PON1 genes would be associated with variation in biochemical phenotypes in a previously unstudied human sample. We determined genotypes of functional genomic variants of APOC3, APOE, FABP2, and PON1 in 509 adult aboriginal Canadians from an isolated community in Northern Ontario. We tested for genotype associations with plasma lipoprotein traits. We found that (1) common variation at nucleotide -455 of the APOC3 promoter was associated with variation in plasma triglycerides (P = .006) and (2) common variation of APOE determining plasma isoforms of apo E was associated with variation in plasma apo B (P = .009). Analysis of subjects classed by APOC3 markers showed that homozygosity for presence of a C at nucleotide -455 and a T at nucleotide -482 was associated with significantly increased plasma triglycerides in both men and women. Furthermore, this allele was approximately twice as frequent in subjects within the highest quartile of plasma triglycerides as in subjects within the lowest quartile. Since the DNA variation detected by the APOC3 markers affects in vitro expression of the gene product, it is possible that the marker itself caused the associations. However, the associations could also have resulted from linkage disequilibrium with other functional variants in APOC3 or the closely linked APOA1 and/or APOA4 genes.

Adolescent↗
PubMed1997

Common genomic variants associated with variation in plasma lipoproteins in young aboriginal Canadians.

We hypothesized that common genomic variants would be associated with variation in lipoprotein phenotypes in young subjects. We determined genotypes of FABP2, PON, APOC3, and APOE in 188 aboriginal Canadians, aged 9 to 17 years. We found that 13 of 32 possible genotype-phenotype associations were significant: (1) the FABP2 codon 54 genotype was associated with variation in plasma triglycerides (P = .045); (2) the PON codon 192 genotype was associated with variation in plasma total and LDL cholesterol and apoB (P = .0099, P = .0088, and P = .016, respectively); (3) the APOC3 insulin-response-element genotype was associated with variation in plasma triglycerides, HDL cholesterol, apoA-I, the total cholesterol to HDL cholesterol ratio, and the apoB to apoA-I ratio (P = .0014, P = .0069, P = .045, P = .0021, and P = .0081, respectively); and (4) the APOE restriction isotype was associated with variation in plasma LDL cholesterol, apoB, the total cholesterol to HDL cholesterol ratio, and the apoB to apoA-I ratio (P = .025, P = .034, P = .045, and P = .047, respectively). The average young age and relative absence of age-dependent secondary environmental factors could have eased the identification of small genetic effects on lipoprotein phenotypes in this study sample.

Adolescent↗
PubMed1997

Angiotensinogen gene variation associated with variation in blood pressure in aboriginal Canadians.

We measured blood pressure and related clinical phenotypes in 497 adult native Canadians from an isolated community in Northern Ontario. We analyzed their DNA for genotypes of angiotensinogen. We found that the frequency of the T235 variant of the angiotensinogen gene was 0.89 in this sample. This variant was associated with a significantly increased systolic pressure but not diastolic pressure. We also found that sex and body mass were each highly significantly associated with variation in both systolic and diastolic pressures. We found a significant association between age and variation in systolic pressure but not diastolic pressure. We also found a highly significant association between plasma apolipoprotein B concentration and variation in diastolic pressure but not systolic pressure. The high frequency of the angiotensinogen T235 variant suggests that subjects in this young, essentially normotensive population might be predisposed to hypertension, which may become more apparent in the presence of secondary factors.

Adult↗
PubMed1997

Paraoxonase-2 gene (PON2) G148 variant associated with elevated fasting plasma glucose in noninsulin-dependent diabetes mellitus.

Defining the genetic determinants of NIDDM requires evidence from several complementary approaches, including both linkage and association analyses using both discrete phenotypes and intermediate quantitative traits. We tested for association between common genomic variation in three genes that map to chromosome 7q21-q22 and quantitative traits related to NIDDM in a sample of Oji-Cree. We found that a common genomic variation in codon 148 (alanine or glycine) of the paraoxonase-2 gene (PON2) demonstrated a significant association with a variation in fasting plasma glucose (P < 0.0001). Furthermore, we found a significant association between a variation in fasting plasma glucose and the interaction term comprised of a PON2 codon 148 genetic variation and the presence of noninsulin-dependent diabetes mellitus (NIDDM; P < 0.0001). We then analyzed subjects according to PON2 genotype and NIDDM status. In subjects with NIDDM, the PON2 codon 148 G/G homozygotes had significantly higher mean fasting plasma glucose than subjects with the other two genotypes (P < 0.0001). However, in non-NIDDM subjects, there was no difference in mean fasting plasma glucose among any of the genotypes. There was no association of the PON2 genotype with NIDDM itself, with impaired glucose tolerance, or with other quantitative traits related to NIDDM in this sample. These findings suggest that 1) the PON2 G148 gene variant worsens glycemia in subjects with NIDDM; 2) defining the physiological role of the PON2 gene product would be worthwhile; and 3) genetic factors can modify the severity of clinical phenotypes in subjects with NIDDM.

Adolescent↗
PubMed1997

The prevalence of NIDDM and associated risk factors in native Canadians.

OBJECTIVE: To determine the true prevalence of impaired glucose tolerance (IGT), NIDDM, and associated risk factors by age and sex in an isolated native community. RESEARCH DESIGN AND METHODS: A community-wide prevalence survey using a 75-g oral glucose tolerance test (OGTT) was undertaken in the remote native reserve of Sandy Lake, Ontario, Canada. Measurements for obesity included waist-to-hip circumference, BMI, and percentage body fat. RESULTS: A total of 728 individuals were enrolled, representing a community participation rate of 72%. The overall crude prevalence of NIDDM was 17.2% (18.1% females and 16.0% males) and increased to 26.1% overall (28.0% females and 24.2% males) when age-standardized. The prevalence of IGT was higher in females compared with males (age-standardized prevalence of 19.8 vs. 7.1%, respectively). Females had a higher prevalence of obesity, IGT, and NIDDM occurring at younger ages. Measures of obesity and fasting insulin levels were significantly associated with NIDDM in the 18-49 age-group. CONCLUSIONS: The prevalence rates of NIDDM in this study population are the highest reported to date in a Canadian native population and among the highest reported in the world. Females appear to be at much higher risk of developing obesity, IGT, and NIDDM and at a younger age. Due to the high prevalence rates of IGT and NIDDM in this young population, there is urgent need to develop culturally appropriate community-based public health intervention programs before the long-term complications of diabetes have a devastating effect on the residents.

Adolescent↗
PubMed1997

Serum immunoreactive leptin concentrations in a Canadian aboriginal population with high rates of NIDDM.

OBJECTIVE: To better understand the relationship between leptin and the anthropometric and physiological variables associated with diabetes, we measured this protein in an isolated Canadian aboriginal population with very high rates of NIDDM. RESEARCH DESIGN AND METHODS: There were 728 individuals aged 10-79 years who participated in a population-based survey to determine the prevalence of NIDDM and its associated risk factors. Fasting blood samples for glucose, insulin, triglyceride, and leptin were collected; a 75-g oral glucose tolerance test was administered and a second blood sample drawn after 120 min. Height, weight, and waist and hip circumference were determined, and percent body fat was estimated using biological impedance analysis. Fitness level was assessed in a subsample of individuals using a validated submaximal step test. The relationship between serum leptin and the other variables was assessed using Spearman's correlation coefficients and multiple linear regression. RESULTS: Serum leptin concentration was strongly correlated with adiposity, and levels were substantially higher in female subjects in all age-groups. For male subjects, percent body fat, fasting insulin level, and waist circumference were significant independent predictors of log serum leptin concentration in a multiple linear regression model (R2 = 0.582). For female subjects, these variables plus glucose tolerance status were included in the final model (R2 = 0.633). Fitness level, when included with the main effects of the above models, was a significant predictor for male subjects only. CONCLUSIONS: In an isolated aboriginal community with high rates of diabetes, we found significant independent relationships between leptin and percent body fat and between leptin and fasting insulin. As documented in other populations, the higher leptin concentration among female subjects may reflect differential leptin production from different adipose tissue beds, or leptin resistance. Independent relationships also existed among leptin and glucose tolerance status in female subjects and fitness level in male subjects.

Adolescent↗
PubMed1997

The epidemiology of diabetes in pregnant Native Canadians. A risk profile.

OBJECTIVE: The purpose of this study was to determine the prevalence of diabetes in pregnancy (gestational diabetes mellitus [GDM] and NIDDM) and to identify risk factors in the development of GDM in a native population in northwestern Ontario, Canada. RESEARCH DESIGN AND METHODS: A retrospective analysis of 1,305 singleton deliveries among Ojibwa-Cree women from northwestern Ontario, Canada, was conducted from 1990 to 1993 inclusive. GDM was diagnosed using a 3-h oral glucose tolerance test (OGTT) and defined according to standard guidelines. RESULTS: The overall prevalence of diabetes in pregnancy (NIDDM and GDM) was 11.6% (152 of 1,305) with a GDM prevalence of 8.4% (110 of 1,305). Among 741 women with complete data, prevalence rates increased with age, peaking at 46.9% in the age-group > or = 35 years. Significant risk factors for GDM included older maternal age, multiparity, prepregnancy obesity, a family history of diabetes, and a history of GDM in previous pregnancies. CONCLUSIONS: Diabetes in pregnancy among Ojibwa-Cree reported here represent the highest rates reported to date in a Canadian population. The high rates of maternal obesity and relative young age of this population further highlight the urgent need for diabetes screening and prevention in this population.

Adolescent↗
PubMed1997

Prevalence of anemia in First Nations children of northwestern Ontario.

OBJECTIVE: To estimate the prevalence of anemia among First Nations children of northwestern Ontario. DESIGN: Retrospective review of all hemoglobin determinations between 1990 and 1992 in the Sioux Lookout Zone. SETTING: The Sioux Lookout Zone Hospital, a secondary care referral hospital for 28 remote First Nations communities in northwestern Ontario, affiliated with the University of Toronto's Sioux Lookout Program. PARTICIPANTS: All First Nations children age 3 to 60 months who had produced venipuncture or fingerprick blood samples between 1990 and 1992 (614 children had a total of 1223 hemoglobin determinations). MAIN OUTCOME MEASURES: Prevalence of anemia by age, sex, geographical location, and diagnosis. Anemia was defined as a hemoglobin value less than 110g/L. RESULTS: Prevalence of anemia peaked in the age range of 6 to 24 months with prevalence rates of 51.7% to 79.3%. Conditions most commonly associated with anemia were respiratory tract infections. Children living in communities in the western part of the Sioux Lookout Zone were 1.64 times more likely to have anemia (95% confidence interval 1.15, 2.35) than children in the other communities. CONCLUSIONS: Anemia appears to be a serious public health problem among preschool children in the Sioux Lookout Zone.

Age Distribution↗
PubMed1996

Body image concepts differ by age and sex in an Ojibway-Cree community in Canada.

Community-based studies of body image concepts can be useful for developing health interventions to prevent obesity-related diseases such as diabetes and cardiovascular disease in specific populations. First Nations peoples, in particular, face increased obesity-related health problems as a result of acculturative changes in diet and activity. This study examined body shape perception in an Ojibway-Cree community in Northern Ontario, Canada. A set of figure outline drawings ranging from very thin to very obese were used to examine perceived body shape, body shape satisfaction and ideals of healthiness across sex and age groups. Overall, only 16% of the population were satisfied with their current body shape. People with a higher body mass index (BMI) were less satisfied with their bodies and thought they were less healthy than people with a lower BMI. While females had a significantly greater BMI than males, males and females did not differ significantly in perception of current body shape. On the other hand, females desired relatively smaller body shapes than males (P < 0.05). Older people chose significantly larger healthy body shapes than did younger people (P < 0.05). Differences between our results and those reported for Anglo populations indicate that while both groups prefer body shapes smaller than those they have currently, the Ojibway-Cree tend to prefer relatively larger body shapes. Knowledge of age and sex-related patterns of body image concepts in communities can assist in the design of obesity-reducing interventions targeting specific groups.

Adolescent↗
PubMed1996

Use of ethnographic methods for applied research on diabetes among the Ojibway-Cree in northern Ontario.

This article presents the results of applied ethnographic research aimed at developing a community-based diabetes prevention program in an isolated Ojibway-Cree community in northern Ontario. Using qualitative techniques, the authors describe diabetes in its sociocultural context and underlying belief systems that affect related activity and dietary behaviors. Local concepts of food and illness are dichotomized into "Indian" and "white man's" groupings, with Indian foods perceived as healthy and white man's foods felt to be unhealthy. Diabetes is believed to result from consumption of white man's "junk foods" (sugar, soda); some believe the disease can be avoided by eating traditional Indian foods such as game animals (moose, beaver, duck). While dietary linkages to diabetes are recognized, physical activity as a means of controlling obesity and decreasing the risk for diabetes is not part of the local ethnomedical model. This information is being used to develop culturally appropriate health education interventions.

Adolescent↗