Shankuan Zhu

The metabolic syndrome is associated with elevated circulating C-reactive protein in healthy reference range, a systemic low-grade inflammatory state.

OBJECTIVE: To elucidate the underlying mechanisms between C-reactive protein (CRP) and cardiovascular disease, we exa-mined the association of circulating CRP in healthy reference range (≤1.0 mg/dl) measured by high-sensitive CRP assay with the metabolic syndrome (MS).DESIGN: Cross-sectional study of circulating CRP in adult men.SUBJECTS: A total of 3692 Japanese men aged 34–69 y.MEASUREMENTS: Serum CRP, total cholesterol, triglycerides, LDL-cholesterol, fasting glucose, fasting insulin, uric acid, systolic blood pressure, diastolic blood pressure, and body mass index (BMI).RESULTS: There was a statistically significant positive correlation between CRP and BMI (r=0.25), total cholesterol (r=0.096), triglycerides (r=0.22), LDL-cholesterol (r=0.12), fasting glucose (r=0.088), fasting insulin (r=0.17), uric acid (r=0.13), systolic blood pressure (r=0.12), and diastolic blood pressure (r=0.11), and a significant negative correlation of CRP with HDL-cholesterol (r=0.24). After adjusting for age, smoking, and all other components of MS, obesity, hypertriglyceridemia, hyper-LDL-cholesterolemia, diabetes, hyperinsulinemia, and hyperuricemia were significantly associated with both mildly (≥0.06 mg/dl) and moderately (≥0.11 mg/dl) elevated CRP. Compared with men who had no such components of the MS, those who had one, two, three, four, and five or more components were, respectively, 1.48, 1.84, 1.92, 3.42, and 4.17 times more likely to have mildly elevated CRP levels (trend P<0.001). As for moderately elevated CRP, the same association was observed.CONCLUSIONS: These results indicate that a variety of components of the MS are associated with elevated CRP levels in a systemic low-grade inflammatory state.

Sleep and Obesity in Preschool Children

OBJECTIVE To examine the relationship between sleep and obesity in children 3 to 4 years old in Shanghai, China. STUDY DESIGN A total of 1311 Chinese children from 10 kindergarten classes in Shanghai, aged 3 to 4 years, who were participating in the kindergarten entrance health examination in 2000, were included in the study. Body weight and height were measured, and a questionnaire was given to the childrens parents about sleep and physical and social characteristics of the children and their family. The main outcome measure was obesity, defined as body mass index (kg/m2) > or = 95th percentile for the children. RESULTS Compared with children reporting > or = 11 hours of sleep per night, the odds ratio for childhood obesity was 4.76 (95% CI, 1.28-17.69) for children with <9 hours of sleep, and 3.42 (95% CI, 1.12-10.46) for children with 9.0 to 9.4 hours of sleep, after adjustment for age, sex, and other risk factors. Children with caregivers who slept less, who had mothers with higher education, or who co-slept with caregivers had less nighttime sleep than other children. CONCLUSION Short sleep duration is positively associated with obesity in preschool children, and short nighttime sleep duration is significantly related to bedtime and co-sleeping with caregivers.

Obesity and Risk for Death Due to Motor Vehicle Crashes

OBJECTIVES We examined the role of body mass index (BMI) and other factors in driver deaths within 30 days after motor vehicle crashes. METHODS We collected data for 22 107 drivers aged 16 years and older who were involved in motor vehicle crashes from the Crashworthiness Data System of the National Automotive Sampling System (1997-2001). We used logistic regression and adjusted for confounding factors to analyze associations between BMI and driver fatality and the associations between BMI and gender, age, seatbelt use, type of collision, airbag deployment, and change in velocity during a crash. RESULTS The fatality rate was 0.87% (95% confidence interval [CI]=0.50, 1.24) among men and 0.43% (95% CI=0.31, 0.56) among women involved as drivers in motor vehicle crashes. Risk for death increased significantly at both ends of the BMI continuum among men but not among women (P<.05). The association between BMI and male fatality increased significantly with a change in velocity and was modified by the type of collision, but it did not differ by age, seatbelt use, or airbag deployment. CONCLUSIONS The increased risk for death due to motor vehicle crashes among obese men may have important implications for traffic safety and motor vehicle design.

Effect of n−3 PUFA supplementation on cognitive function throughout the life span from infancy to old age: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND n-3 PUFAs play an important role in cognitive function. OBJECTIVE The objective was to investigate the effect of n-3 PUFA supplements on cognitive development, function, and decline throughout the life span. DESIGN The study included randomized controlled trials and provided ≥3 mo of treatment. Potential studies were independently screened in duplicate, and study characteristics and outcomes were extracted. A meta-analysis was performed by using fixed- or random-effects models. The results are presented as standardized mean differences (SMDs) with 95% CIs. RESULTS Of the 3692 citations retrieved, 34 studies of a total of 12,999 participants (1031 infants, 1517 children, 3657 adults, and 6794 elderly individuals) were included. Compared with placebo, n-3 PUFA supplements significantly improved cognitive development in infants, including the Mental Development Index (SMD: 0.33; 95% CI: 0.15, 0.52), the Psychomotor Development Index (0.27; 95% CI: 0.09, 0.45), and language (0.27; 95% CI: 0.13, 0.42), motor (0.29; 95% CI: 0.14, 0.43), and cognitive (0.31; 95% CI: 0.16, 0.45) abilities. However, n-3 PUFAs did not promote cognitive function in terms of composite memory, executive function, and processing speed domains in children, adults, or the elderly, except for the attention domain. No association was found between n-3 PUFA intake and improvements in cognitive performance in terms of recognition, immediate and delayed word recall, digit span backward and forward tests, rapid visual information processing, verbal fluency, and simple and choice reaction times. In addition, n-3 PUFA supplements were not associated with improvements in cognitive decline or with any effects on Alzheimer disease in elderly people. CONCLUSIONS n-3 PUFA supplements may significantly improve cognitive development in infants but do not improve cognitive performance in children, adults, or the elderly. n-3 PUFA intake, especially that of DHA supplements, may benefit cognitive development during infancy.

Associations of Body Mass Index and Anthropometric Indicators of Fat Mass and Fat Free Mass with All-cause Mortality among Women in the First and Second National Health and Nutrition Examination Surveys Follow-up Studies

PURPOSE This study tests whether fat mass (FM) and fat free mass (FFM) have opposite associations with mortality in a nationally representative sample of females. METHODS Data on 13,369 female participants from National Health and Nutrition Examination Surveys (NHANES) I and II (aged 25 to 75 years) were analyzed. Mean follow-up time was 16.1 years. Ninety-seven percent of the participants with 3020 deaths were successfully followed. Subscapular and triceps skinfolds thickness were used as a FM indicator (FMI). Upper arm circumference was used as a FFM indicator (FFMI). Cox regression tested the relationships of BMI, FM and FFM with all-cause mortality adjusting for various socio-demographic variables. RESULTS BMI had a U-shaped relationship with mortality with a nadir of approximately 27 kg/m(2). When FFMI was added to the model, the relationship between BMI and mortality became more monotonic increasing. FMI showed a significant negative relationship with mortality. CONCLUSIONS Contrary to expectations, both FFMI and FMI had negative relationships with mortality. These results differ from patterns previously observed in males and may reflect sex differences in fat distribution. Research using superior measures of body fat amount and distribution may resolve these discrepancies.

Bias in Estimates of Quantitative-Trait–Locus Effect in Genome Scans: Demonstration of the Phenomenon and a Method-of-Moments Procedure for Reducing Bias

An attractive feature of variance-components methods (including the Haseman-Elston tests) for the detection of quantitative-trait loci (QTL) is that these methods provide estimates of the QTL effect. However, estimates that are obtained by commonly used methods can be biased for several reasons. Perhaps the largest source of bias is the selection process. Generally, QTL effects are reported only at locations where statistically significant results are obtained. This conditional reporting can lead to a marked upward bias. In this article, we demonstrate this bias and show that its magnitude can be large. We then present a simple method-of-moments (MOM)-based procedure to obtain more-accurate estimates, and we demonstrate its validity via Monte Carlo simulation. Finally, limitations of the MOM approach are noted, and we discuss some alternative procedures that may also reduce bias.

BMI and Risk of Serious Upper Body Injury Following Motor Vehicle Crashes: Concordance of Real-World and Computer-Simulated Observations

Shankuan Zhu and colleagues use computer crash simulations, as well as real-world data, to evaluate whether driver obesity is associated with greater risk of body injury in motor vehicle crashes.

Long-term body weight variability is associated with elevated C-reactive protein independent of current body mass index among Japanese men

OBJECTIVE: To elucidate the effect of long-term weight variability on C-reactive protein (CRP) levels.DESIGN: Cross-sectional study of the circulating CRP.SUBJECTS: A total of 637 Japanese men aged 40–49 y in1997.MEASUREMENTS: Serum CRP levels, body mass index in 1997 (current BMI), the slope of weight on age (weight-slope) representing an individuals weight trend of direction and magnitude, and the root mean square error around the slope of weight on age (weight-RMSE) representing the weight fluctuation magnitude, as calculated by a simple linear regression model in which each value of the subjects five actual weights (aged 20, 25, 30 y, five years ago, and current) was a dependent variable and the subjects ages independent variables.RESULTS: After adjustment for age and confounders, including smoking and health status, the odds ratios of elevated CRP (≥0.06 mg/dl) were 1.83 (95% CI: 1.25–2.69), 2.63 (1.69–4.11), and 10.31 (2.17–48.98) for upper normal-weight (BMI: 22–<25 kg/m2), overweight (25–<30), and obese (≥30) persons, respectively, compared with lower normal-weight persons (18.5–<22). Adjusting for age, confounders, and current BMI, weight-slope was positively associated with CRP level especially among subjects with BMI≥25 kg/m2 (trend P<0.01), and weight-RMSE was positively associated with CRP level particularly among subjects with BMI <25 kg/m2 (trend P<0.05).CONCLUSION: Our results suggest a state of low-grade systemic inflammation not only in overweight and obese persons, but also in normal-weight persons with large weight fluctuation, possibly explaining in part the positive association between weight fluctuation and CVD.

Association between sleep duration and bone mineral density in Chinese women

BACKGROUND Short sleep duration has been found to be closely related to several endocrine and metabolic dysfunctions. However, evidence of the association between insufficient sleep and bone health was limited. OBJECTIVE The present study was aimed to examine the relationships between sleep duration and bone mineral density (BMD) in Chinese women. METHODS Six hundred and two women aged 18-80 years were analyzed. Sleep duration was collapsed to form categories of 5h or less, 6h, 7h, 8h, and 9h or more. Total and regional BMD were measured using dual-energy X-ray absorptiometry. Multiple regression analysis was performed to examine the relationships between sleep duration categories and BMD. RESULTS Women with a short sleeping duration were more likely to have lower total and all body regional BMD after adjusting for potential covariates (all p values for trend <0.05). Compared to those who slept 8h, individuals who slept 5h or less and 6h had significant lower total and regional BMD (β coefficients ranged -0.07 to -0.11, all p<0.05). When further divided women into 18-44 years old and 45 years or older groups, and reran the regression models, the significant associations between BMD and sleep duration were only observed in 45 years or older group. CONCLUSIONS Significant variations in total and regional BMD with sleep duration were observed in women. Decreased sleep duration closely associated with lower BMD, especially in middle-age and elderly women. These findings may lead to the development of better preventive approaches to osteoporosis in women through identification of potential modifiable risk factors.

Estimation of percentage body fat by dual-energy x-ray absorptiometry: evaluation by in vivo human elemental composition

Dual-energy x-ray absorptiometry (DXA) is widely applied for estimating body fat. The percentage of body mass as fat (%fat) is predicted from a DXA-estimated R(ST) value defined as the ratio of soft tissue attenuation at two photon energies (e.g., 40 keV and 70 keV). Theoretically, the R(ST) concept depends on the mass of each major element in the human body. The DXA R(ST) values, however, have never been fully evaluated by measured human elemental composition. The present investigation evaluated the DXA R(ST) value by the total body mass of 11 major elements and the DXA %fat by the five-component (5C) model, respectively. Six elements (i.e. C, N, Na, P, Cl and Ca) were measured by in vivo neutron activation analysis, and potassium (i.e. K) by whole-body (40)K counting in 27 healthy adults. Models were developed for predicting the total body mass of four additional elements (i.e. H, O, Mg and S). The elemental content of soft tissue, after correction for bone mineral elements, was used to predict the R(ST) values. The DXA R(ST) values were strongly associated with the R(ST) values predicted from elemental content (r = 0.976, P < 0.001), although there was a tendency for the elemental-predicted R(ST) to systematically exceed the DXA-measured R(ST) (mean +/- SD, 1.389 +/- 0.024 versus 1.341 +/- 0.024). DXA-estimated %fat was strongly associated with 5C %fat (24.4 +/- 12.0% versus 24.9 +/- 11.1%, r = 0.983, P < 0.001). DXA R(ST) is evaluated by in vivo elemental composition, and the present study supports the underlying physical concept and accuracy of the DXA method for estimating %fat.