Obesity as a risk factor for cardiovascular disease

Purinergic P2X7 receptor functional genetic polymorphisms are associated with the susceptibility to obesity in Chinese postmenopausal women

OBJECTIVE

We conducted a case-control study to investigate the associations of functional single-nucleotide polymorphisms in the purinergic P2X7 receptor (P2X7R) gene (rs2393799, rs7958311, rs1718119, rs2230911, and rs3751143) with obesity and overweight in a population of Chinese postmenopausal women.

METHODS

Our study included 180 obese women, 179 overweight women, and 204 controls. All participants were genotyped at the P2X7R rs2393799, rs7958311, rs1718119, rs2230911, and rs3751143 loci via allele-specific polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism procedures. The relationships between P2X7R genetic polymorphisms and their associated haplotypes with obesity (body mass index [BMI] ≥30 kg/m] and overweight (25 kg/m ≤ BMI < 30 kg/m) were evaluated.

RESULTS

Our results showed that P2X7R rs2230911G and rs1718119A were associated with an increased risk of obesity; in particular, both carriers of the rs2230911G allele and GG/(CG + GG) genotypes (G vs C, P < 0.001, odds ratio [OR] 2.87, 95% confidence interval [CI] 1.98-4.16; GG vs CC, P < 0.001, OR 8.76, 95% CI 3.29-23.35; CG + GG vs CC, P < 0.001, OR 2.54, 95% CI 1.63-3.95) and carriers of the rs17181191A allele and GA/(GA + AA) genotypes (A vs G, P < 0.001, OR 2.97, 95% CI 1.86-4.74; GA vs GG, P = 0.001, OR 2.72, 95% CI 1.55-4.79; GA + AA vs GG, P < 0.001, OR 3.05, 95% CI 1.79-5.19) were at a higher risk of obesity. No association with obesity or overweight was observed for the other three P2X7R polymorphisms (rs2393799, rs7958311, and rs3751143). Haplotype analysis indicated that P2X7R rs1718119A-rs2230911G-rs3751143C appeared to be a significant risk haplotype with obesity (P = 0.0005, OR 2.37, 95% CI 1.45-3.90).

CONCLUSIONS

P2X7R functional genetic polymorphisms and their estimated haplotypes are associated with obesity in Chinese postmenopausal women.

Effects of Body Mass Index on the Lipid Profile and Biomarkers of Inflammation and a Fibrinolytic and Prothrombotic State

AIM

Both an overweight status and obesity are associated with high cardiovascular morbidity and mortality. The aim of this study was to examine the effects of obesity on different underlying mechanisms, i.e. inflammation, fibrinolysis and a prothrombotic state, in a young high-risk population in the Mediterranean area.

METHODS

The study population included 237 subjects (median age: 44 years). We recorded the presence of cardiovascular risk factors and premature ischaemic heart disease and performed weight stratification using the body mass index (BMI) according to the established World Health Organization (WHO) criteria. We also measured the serum/plasma lipid, fibrinogen, D-dimer, von Willebrand factor, tissue plasminogen activator antigen (t-PA), plasminogen activator inhibitor-1 antigen (PAI-1) and high-sensitivity C-reactive protein (CRP-hs) levels in samples of peripheral blood.

RESULTS

The subjects with premature ischaemic heart disease and hypertension had higher BMI values (p＜0.01), and the subjects with an increased weight showed an unadjusted detrimental lipid profile, with a proinflammatory, prothrombotic state and abnormal fibrinolytic parameters. According to a multivariate analysis, the HDL-cholesterol (r(2)=0.176; p＜0.001), t-PA antigen (r(2)=0.235; p＜0.001), PAI-1 antigen (r(2)=0.164; p＜0.001) and CRP-hs (r(2)=0.096; p=0.019) levels were significantly related to the weight stratification.

CONCLUSIONS

A high BMI is a common finding in young populations at high risk of cardiovascular disease. In the current study, the patients with an increased BMI demonstrated an unhealthy lipid profile, as well as a proinflammatory and prothrombotic state and abnormal fibrinolytic parameters.

Correlation between body mass index and waist circumference in nigerian adults: implication as indicators of health status

BACKGROUND

Anthropometric measures have been widely used for body weight classification in humans. Waist circumference has been advanced as a useful parameter for measuring adiposity. This study evaluated the correlation between body mass index (BMI) and waist circumference and examined their significance as indicators of health status in adults.

DESIGN AND METHODS

The subject included 489 healthy adults from Ota, Nigeria, aged between 20 and 75 years, grouped into early adulthood (20-39 years), middle adulthood (40-59 years) and advanced adulthood (60 years and above). Weight, height and abdominal circumference were measured. BMI was calculated as weight kg/height2 (m2) and World Health Organization cut-offs were used to categorize them into normal, underweight, overweight and obese.

RESULTS

Abnormal weight categories accounted for 60 % of the subjects (underweight 11 %, overweight 31%, and obese 18%). The waist circumference of overweight and obese categories were significantly (P<0.05) higher than the normal weight category. There was no significant difference between waist circumference of underweight and normal subjects. The correlation coefficient values of BMI with waist circumference (r=0.63), body weight (r=0.76) and height (r=-0.31) were significant (P<0.01) for the total subjects.

CONCLUSIONS

The study indicates that waist circumference can serve as a positive indicator of overweight and obesity in the selected communities; however, it may not be used to determine underweight in adults. Regular BMI and waist circumference screening is recommended as an easy and effective means of assessing body weight and in the prevention of weight related diseases in adults. Significance for public healthThis manuscript describes the correlation between body mass index, waist circumference and body weight of two communities in Ota, Ogun State, Nigeria and the use of these anthropometric measures for body weight classification in human populations of the selected communities. This was carried out to evaluate the health status of the indigenes of the two communities for proper health awareness and public health intervention programmes.

Moderate Exercise and Fibrinolytic Potential in Obese Sedentary Men with Metabolic Syndrome

OBJECTIVE

To investigate the impact of 30-minute walking exercise at 70% VO2max on tissue plasminogen activator (t-PA) Ag and plasminogen activator inhibitor type 1 (PAI-1) Ag in obese sedentary males.

RESEARCH METHODS AND PROCEDURES

A controlled observational study of the effect of a 30-minute acute exercise bout at 70% VO2max on plasma t-PA antigen and PAI-1 antigen in 10 obese sedentary males matched for age, ethnic origin, and smoking status with 10 nonobese sedentary male controls.

RESULTS

The obese group remained hypofibrinolytic compared with the nonobese group at all time-points before, during, and after exercise. t-PA increased in both groups with exercise before returning to baseline values 30 minutes after exercise. PAI-1 did not significantly change in either group with exercise but rose significantly 30 minutes after exercise in the obese group.

DISCUSSION

The reduction in fibrinolytic potential in the obese group represents an increase in acute thrombotic risk and could account for the increased incidence of exercise-associated myocardial infarction observed in sedentary obese groups.

Rapid increases in obesity in Jamaica, compared to Nigeria and the United States

Background

Weight gain in adulthood is now common in many populations, ranging from modest gains in developing countries to a substantial percentage of body weight in some Western societies. To examine the rate of change across the spectrum of low to high-income countries we compared rates of weight change in samples drawn from three countries, Nigeria, Jamaica and the United States.

Methods

Population samples from Nigeria (n = 1,242), Jamaica (n = 1,409), and the US (n = 809) were selected during the period 1995–1999 in adults over the age of 19; participation rates in the original survey were 96%, 60%, and 60%, respectively. Weight in (kg) was measured on 3 different occasions, ending in 2005. Multi-level regression models were used to estimate weight change over time and pattern-mixture models were applied to assess the potential effect of missing data on estimates of the model parameters.

Results

The unadjusted weight gain rate (standard error) was 0.34(0.06), 1.26(0.12), 0.34(0.19) kg/year among men and 0.43(0.06), 1.28(0.10), 0.40(0.15) kg/year among women in Nigeria, Jamaica, US, respectively. Regression-adjusted weight change rates were significantly different across country, sex, and baseline BMI. Adjusted weight gain in Nigeria, Jamaica and US was 0.31(0.05), 1.37(.04), and 0.52(0.05) kg/year respectively. Women in Nigeria and the US had higher weight gains than men, with the converse observed among Jamaicans. The obese experienced weight loss across all three samples, whereas the normal weight (BMI < 25) had significant weight gains. Missing data patterns had an effect on the rates of weight change.

Conclusion

Weight change in sample cohorts from a middle-income country was greater than in cohorts from either of the low- or high-income countries. The steep trajectory of weight gain in Jamaica, relative to Nigeria and the US, is most likely attributable to the accelerating effects of the cultural and behavioral shifts which have come to bear on transitional societies.

The anti-obesity effect of rimonabant is associated with an improved serum lipid profile

We investigated the effects of chronic treatment with the CB1 receptor antagonist rimonabant (10 mg/kg/day p.o. for 10 weeks) in mice with established obesity (5-month high-fat diet). Untreated obese mice showed a weight gain of 46% (45.0 +/- 0.6 g vs. 30.8 +/- 0.5 g) compared with age-matched animals fed a standard diet. Rimonabant treatment, commencing after 5-month high-fat diet, produced a marked and sustained decrease in body weight (34.5 +/- 0.8 g vs. 47.2 +/- 0.5 g in the high-fat vehicle group, p < 0.001). The anti-obesity effect of rimonabant was similar to that obtained by switching obese mice from high-fat diet to standard laboratory diet during 10 weeks (final weight 33.7 +/- 0.6 g) and was associated with only transient (14 days) reduction in energy intake. Serum leptin, insulin and glucose levels were markedly elevated in obese animals. Rimonabant treatment significantly reduced these elevations (leptin -81%, insulin -78%, glucose -67%, p < 0.001 in all cases vs. high-fat vehicle group). In addition, rimonabant treatment modestly but significantly increased serum adiponectin levels (+18%, p < 0.05 vs. high-fat vehicle group). Obese mice demonstrated abnormal serum lipid profiles. Although rimonabant did not modify high-density lipoprotein cholesterol (HDLc) and had modest effects on total cholesterol, it significantly reduced triglycerides and low-density lipoprotein cholesterol (LDLc) and, notably, increased the HDLc/LDLc ratio (12.4 +/- 0.8 vs. 7.9 +/- 0.2 in high-fat vehicle group, p < 0.001). Therefore, in a model of established obesity, chronic rimonabant treatment produces a marked and sustained decrease in body weight (equivalent to that achieved by dietary change) which is associated with favourable modifications in serum biochemical and lipid profiles.

Relationship among habitual tea consumption, percent body fat, and body fat distribution

OBJECTIVE

To disclose the possible relationship between habitual tea consumption and changes in total body fat and fat distribution in humans.

RESEARCH METHODS AND PROCEDURES

A cross-sectional survey of 1,210 epidemiologically sampled adults (569 men and 641 women) were enrolled in our study. Tea consumption and other lifestyle characteristics were obtained by structured questionnaires. Percent body fat (BF%) was measured using bioelectrical impedance analysis. Body fat distribution was assessed using waist-to-hip ratio (WHR).

RESULTS

Among the 1,103 analyzed subjects, 473 adults (42.9%) consumed tea once or more per week for at least 6 months. The habitual tea drinkers were male-dominant, more frequently current smokers, and alcohol or coffee drinkers than the nonhabitual tea drinkers. Habitual tea drinkers for more than 10 years showed a 19.6% reduction in BF% and a 2.1% reduction in WHR compared with nonhabitual tea drinkers. The multiple stepwise regression models revealed that men, older age, higher BMI, and current smokers were positive factors for BF% and WHR. In contrast, longer duration of habitual tea consumption and higher total physical activity were negative factors for BF%. Longer duration of habitual tea consumption, higher socioeconomic status, and premenopausal status were negative factors for WHR.

DISCUSSION

An inverse relationship may exist among habitual tea consumption, BF%, and body fat distribution, especially for subjects who have maintained the habit of tea consumption for more than 10 years.

Homeostasis model assessment of insulin resistance in relation to the incidence of cardiovascular disease: the San Antonio Heart Study

OBJECTIVE

The prospective association between insulin levels and risk of cardiovascular disease (CVD) is controversial. The objective of the present study was to investigate the relationship of the homeostasis model assessment of insulin resistance (HOMA-IR), as well as insulin levels, with risk of nonfatal and fatal CVD over the 8-year follow-up of the San Antonio Heart Study.

RESEARCH DESIGN AND METHODS

Between 1984 and 1988, randomly selected Mexican-American and non-Hispanic white residents of San Antonio participated in baseline examinations that included fasting blood samples for glucose, insulin, and lipids, a glucose tolerance test, anthropometric measurements, and a lifestyle questionnaire. Between 1991 and 1996, 2,569 subjects who were free of diabetes at baseline were reexamined using the same protocol.

RESULTS

Over the follow-up period, 187 subjects experienced an incident cardiovascular event (heart attack, stroke, heart surgery, angina, or CVD death). Logistic regression analysis indicated that risk of a CVD event increased across quintiles of HOMA-IR after adjustment for age, sex, and ethnicity (P for trend <0.0001; quintile 5 vs. quintile 1, odds ratio [OR] 2.52, 95% CI 1.46-4.36). Additional adjustment for LDL, triglyceride, HDL, systolic blood pressure, smoking, alcohol consumption, exercise, and waist circumference only modestly reduced the magnitude of these associations (P for trend 0.02; quintile 5 vs. quintile 1, OR 1.94, 95% CI 1.05-3.59). Furthermore, there were no significant interactions between HOMA-IR and ethnicity, sex, hypertension, dyslipidemia, glucose tolerance (impaired glucose tolerance versus normal glucose tolerance), or obesity. The magnitude and direction of the relationship between insulin concentration and incident CVD were similar.

CONCLUSIONS

We found a significant association between HOMA-IR and risk of CVD after adjustment for multiple covariates. The topic remains controversial, however, and additional studies are required, particularly among women and minority populations.

Down-regulation of heart HFABP and UCP2 gene expression in diet-induced (cafeteria) obese rats

Long-term exposure to hypercaloric high fat diet induced marked tissue fatty acid accumulation and may influence cell function. Previous results in our laboratory showed that uncoupling proteins (UCPs) and fatty acid-binding protein (FABP) gene expression are changed in adipose tissue and skeletal muscle tissue in diet-induced (cafeteria) obese animals. The aim of this study was to examine heart FABP (HFABP) and UCP2 gene expressions in dietary obese rats. Rats fed on a high-fat diet for 65 days had significantly higher fat stores and body weight than control rats. Interestingly, we found that both HFABP and UCP2 mRNA levels were significantly reduced in cafeteria-obese rats when compared to control animals. Moreover, a statistically significant correlation was observed between the two gene expression levels. The down-regulation of heart HFABP and UCP2 parallels the lower lipid utilization which may account for an enhanced fat deposition. It is plausible that these two genes are regulated by the same family of transcription factors.

Differences in the relation of obesity to serum triacylglycerol and VLDL subclass concentrations between black and white children: the Bogalusa Heart Study

BACKGROUND

Obese children and adults, particularly those with abdominal obesity, have an elevated serum triacylglycerol concentration. Furthermore, triacylglycerol concentrations are generally higher in whites than in blacks, and the relation of obesity to triacylglycerol concentrations may be stronger in whites. However, there is little information on the relation of obesity to the metabolically distinct subclasses of VLDL in children.

OBJECTIVE

The objective was to examine possible differences between blacks (n = 367) and whites (n = 549) in mean concentrations of triacylglycerols, in mean concentrations of small and large VLDL, and in the relation of waist circumference to concentrations of triacylglycerol and VLDL subclasses.

DESIGN

We measured VLDL subclass concentrations and assessed the relation of various obesity indexes to triacylglycerols in a cross-sectional study of 10- to 17-y-olds.

RESULTS

The mean triacylglycerol concentration was 0.3 mmol/L (25 mg/dL) higher in white than in black children, primarily because of a 0.2-mmol/L (140%) difference in mean concentrations of large VLDL. In contrast, the mean concentrations of small VLDL differed by only 0.05 mmol/L (29%). In addition, the relations of waist girth to concentrations of triacylglycerol and large VLDL were 2- to 6-fold stronger among white children than among black children. Although white children had higher concentrations of large VLDL than did black children, this difference increased from 0.1 to 0.4 mmol/L across quintiles of waist circumference. Waist circumference was not significantly related to concentrations of small VLDL.

CONCLUSION

These contrasting associations with obesity, which differ between white and black children, suggest that information on VLDL subclasses could provide additional information on the risk of obesity-related ischemic heart disease.