Pathophysiologic mechanisms of obesity and related metabolic disorders: an epidemiologic study using questionnaire and serologic biomarkers

Association Between Weight Gain From Young to Middle Adulthood and Metabolic Syndrome Across Different BMI Categories at Young Adulthood

OBJECTIVES

We aimed to assess the dose-response association between weight gain from young to middle adulthood and odds of metabolic syndrome, across body mass index (BMI) categories at young adulthood.

METHODS

Based on a national population-based screening project, middle-aged (35-64 years) participants who recalled weight at age 25 years and received standardized measurements were included. Multivariable adjusted restricted cubic splines and logistic regression models were applied.

RESULTS

In total, 437,849 participants were included (62.1% women, 52.0 ± 7.6 years). Larger weight gains from young to middle adulthood were associated with higher odds of metabolic syndrome at middle adulthood, with odds of 2.01 (1.98-2.05), 1.93 (1.92-1.94), and 1.67 (1.64-1.7) per 5-kg weight gain across participants who were underweight, normal-weight, and overweight/obese at young adulthood, respectively. After further adjusting for current BMI, larger weight gains still correlated with higher odds of metabolic syndrome among underweight and normal-weight participants, while an inverted U-shaped association was observed in overweight/obese participants.

CONCLUSIONS

Weight maintenance from young to middle adulthood could be effective to mitigate metabolic syndrome burden, especially among underweight and normal-weight people. Historical weight gain confers varied information about metabolic syndrome risk independent of attained BMI across BMI categories at young adulthood.

Impact of Obesity and Ozone on the Association Between Particulate Air Pollution and Cardiovascular Disease and Stroke Mortality Among US Adults

Background

Cardiovascular diseases (CVDs) and stroke are the highest and third highest causes of death, respectively, in the whole United States. It is well established that both long‐ and short‐term exposure to particulate air pollution (particulate matter with diameters <2.5 μm [PM_2.5]) increases the risks of both CVD and stroke mortality.

Methods and Results

We combined county‐level data for CVD and stroke mortality, and prevalence of hypertension and obesity, with spatial patterns of PM_2.5 and ozone in a cross‐sectional ecological study. We found significant positive associations between both CVD (β=15.4, P<0.001) and stroke (β=2.7, P<0.001) mortality with PM_2.5. Ozone had significant link with just CVD (β=1372.1, P<0.001). Once poverty, ethnicity, and education were taken into account, there were still significant positive associations between PM_2.5 and both CVD (β=1.2, P<0.001) and stroke (β=1.1, P<0.001) mortality. Moreover, the association between CVD and ozone remained after adjustment for these factors (β=21.8, P<0.001). PM_2.5 and ozone were independent risk factors. The impact of PM_2.5 on CVD and stroke mortality was strongly dependent on the prevalence of obesity. Hypertension partially mediated the associations of PM_2.5 and mortality from CVD and stroke.

Conclusions

There was a spatial association between PM_2.5 exposure and the leading causes of death and disability in United States. The effect of PM_2.5 was considerably greater in areas where obesity is more prevalent. Hypertension is a possible mediator of the association of PM_2.5 and both CVD and stroke.

Exposure to fine particulate matter and acute effects on blood pressure: effect modification by measures of obesity and location

BACKGROUND

Observational studies and controlled experiments have provided evidence that airborne particulate matter (PM) is capable of acutely increasing blood pressure (BP) in certain scenarios. The goal of this study was to evaluate whether and to what extent obesity and community location affect relationships between fine particulate matter (PM(2.5)) and blood pressure (BP) measures.

METHODS

Using data from a stratified random sample survey of adults conducted in 2002-3 in Detroit, Michigan, we tested body mass index (BMI) and waist circumference (WCIR) in separate models as effect modifiers of the relationship between PM(2.5) exposure and BP. We also tested interactions with community location. Models were adjusted for covariates with established pro-hypertensive effects.

RESULTS

PM(2.5) exposure was positively associated with increased pulse pressure (PP) for those categorised as obese (BMI> or =30) across lags 2 (beta 4.16, p<0.05) and 3 days (beta 2.55, p<0.05) prior to BP measure. WCIR similarly modified the effect of exposure to PM(2.5) on PP (beta 4.34, p<0.003). The observed effects were enhanced in the community with closer proximity to local emissions of PM(2.5), and for residents classified as obese (BMI> or =30) or with WCIR above high-risk cuts points.

CONCLUSIONS

This community-based study suggests that positive associations between PM(2.5) exposure and PP and systolic BP are enhanced in areas proximate to sources of PM (2.5) emissions. These patterns were observed for all residents, but were more visible and consistent among those who were obese. Research is needed to examine the mechanistic pathways by which air particles interact with obesity and location to affect BP, and inform community interventions to reduce the population burden of hypertension and related co-morbidities.

Incidence of metabolic syndrome according to combinations of lifestyle factors among middle-aged Japanese male workers

OBJECTIVE

To examine a combination of healthy lifestyles on the risk of metabolic syndrome (MetS) to inform future interventions.

METHODS

A total of 1897 men aged 35-60 years participated in an annual health check-up in 2002 and 2005. MetS was defined by AHA/NCEP criteria. Logistic regression analyses were used to estimate age- and BMI-adjusted odds ratios (ORs) of MetS incidence for each healthy lifestyle (regular physical activity, adherence to healthy eating behaviors, not current smoking, and maintaining a stable weight since one's mid-twenties), separately (Model 1) and simultaneously (Model 2). A points system was developed to derive 3-year risk of MetS incidence by assigning a specific point to each healthy lifestyle.

RESULTS

MetS developed in 285 (15.0%) subjects after the follow-up. The ORs of MetS for each healthy lifestyle ranged from 0.42 to 0.64 (Model 2). Three-year risk of MetS incidence was predicted to differ from 1% to 60% according to the individual point total of the points system. The population-attributable fraction of MetS in subjects whose point total was not in the highest quartile was 71%.

CONCLUSION

Adherence to healthy lifestyles was associated with a lower risk of MetS among apparently healthy middle-aged Japanese male workers.

Development of new quantitative diagnosis machine to evaluate the baroreflex sensitivity of an artery for patients with hypertension

Text book in all medical school showed that the baroreflex system is one of the most important regulatory systems. When blood pressure increases, heart rate decrease and an artery is dilated with the baroreflex system. By decrease of cardiac output and arterial resistances, blood pressure returns to the normal value. However, there is no diagnostic method, which can measure the sensitivity of a baroreflex system of the artery by the simple methodology. We had challenged invention of the new machine, which could diagnose the sensitivity of the baroreflex system of not only a heart, but also an artery. In this system, the measurement sections are only an electrocardiography (ECG) and peripheral pulse wave. These time series is inputted into a personal computer system, and analyzed quantitatively. Responses of the artery were measured with pulse wave velocity (PWV) calculated from pulse wave transmission time from heart to an artery. In this system, the heart rate change corresponding to the blood-pressure change in time series sequence is observed. Delay time was measured by the cross correlation function. Slope of the blood pressure (BP) change and heart rate (HR) change showed the sensitivity of the baroreflex system of heart. Furthermore, this system can measure the sensitivity of the baroreflex system of an artery. Change of PWV in response to the BP change was observed. We found that significant correlation was observed in the time sequence between BP change and PWV change after delay time calculated from cross correlation. Clinical research was started through allowance of the Ethics Committee. Decreased sensibility in the hypertensive patient's baroreflex system was observed as a result of the clinical research. Furthermore, alteration of the baroreflex sensitivity before and after the drug administration was evaluated. For example, Azelnidipine, Calcium antagonists improved the baroreflex sensitivity of the artery in several cases. This system may be useful f- or the follow up of the hypertensive patients.

Distinct patterns of fat metabolism in skeletal muscle of normal-weight, overweight, and obese humans

The link between body weight, lipid metabolism, and health risks is poorly understood and difficult to study. Magnetic resonance spectroscopy (MRS) permits noninvasive investigation of lipid metabolism. We extended existing two-dimensional MRS techniques to permit quantification of intra- and extramyocellular lipid (IMCL and EMCL, respectively) compartments and their degree of unsaturation in human subjects and correlated these results with body mass index (BMI). Using muscle creatine for normalization, we observed a statistically significant (P < 0.01) increase in the IMCL-to-creatine ratio with BMI (n = 8 subjects per group): 5.9 +/- 1.7 at BMI < 25, 10.9 +/- 1.82 at 25 < BMI < 30, and 13.1 +/- 0.87 at BMI > 30. Similarly, the degree of IMCL unsaturation decreased significantly (P < 0.01) with BMI: 1.51 +/- 0.08 at BMI < 25, 1.30 +/- 0.11 at 25 < BMI < 30, and 0.90 +/- 0.14 at BMI > 30. We conclude that important aspects of lipid metabolism can be evaluated by two-dimensional MRS and propose that degree of unsaturation measured noninvasively may serve as a biomarker for lipid metabolic defects associated with obesity.