Age variations in the relation of body mass indices to estimates of body fat and muscle mass

In some chronic disease studies, distinctions have been made regarding the importance of body mass index (BMI) as a risk factor in younger versus older men and women. In order to determine the significance of these differences in BMI-disease associations, we determined the extent of age-dependent variations in the relation of BMIs to body composition in large probability samples of U.S. men and women from the First and Second U.S. National Health and Nutrition Examination Surveys (NHANES I and II). BMIs are more highly correlated with estimates of body fat in younger than in older men and women, and with muscle mass in older than in younger adults. Caution should be exercised in interpreting the significance of BMI as a risk factor for chronic disease, particularly in comparison of age groups.     

Effects of five days of bed rest with intermittent centrifugation on neurovestibular function

Objectives:

We tested whether intermittent short-radius centrifugation was effective for mitigating alteration in balance and gait following bed rest.

Methods:

Ten male subjects were exposed to 5 days of 6° head-down tilt bed rest with: (a) no countermeasure; (b) daily 1-g centrifugation for a continuous 30-min period; and (c) daily 1-g centrifugation for six periods of 5 min. During and after the bed rest, subjects were asked to scale the severity of neurovestibular symptoms that followed centrifugation or 80º head-up tilt. Following the bed rest, equilibrium scores were derived from anterior-posterior sway while standing on a foam pad with the eyes open or closed while making pitch head movements, and gait was evaluated by grading subjects’ performance during various locomotion tasks.

Results:

At the beginning of bed rest, one single 30-min period of centrifugation induced more severe neurovestibular symptoms than six periods of 5-min centrifugation. After bed rest, although equilibrium scores and gait performance were not significantly altered, subjects felt less neurovestibular dysfunction with orthostatic stress when centrifugation was used.

Conclusion:

Centrifugation was effective at reducing the severity of neurovestibular symptoms after bed rest, but this decrease was not different between one or multiple daily sessions.     

Impact of the Fukushima nuclear accident on obesity of children in Japan (2008–2014)

This study used prefecture-level panel data from Japan for the period 2008–2014 to investigate the influence of the 2011 Fukushima nuclear accident on the body mass index (BMI) z-score and obesity rates of children over time. I adopted a difference-in-differences approach and found the following: (1) for the cohort aged 5–7 years in 2010, the BMI z-score and obesity rates in disaster-affected areas were higher than in other areas, although this was not observed for the other cohorts; (2) for the cohort aged 5–7 years in 2010, the influence of the accident persisted even after 3 years; and (3) the differences in the BMI z-score and obesity rate before and after the accident were greater for Fukushima Prefecture than for the other affected areas (Iwate and Miyagi prefectures). I infer that health-conscious parents, whose children had lower BMIs, may have moved from Fukushima, thereby increasing the BMI z-score of the child population living in Fukushima by around 0.05 for the cohort aged 5–7 years. The enforced reduction in physical activity increased the BMI z-score of children living in Fukushima by around 0.19 for that cohort.     

Adjusting body mass for measurement error with invalid validation data

We propose a new method for using validation data to correct self-reported weight and height in surveys that do not measure respondents. The standard correction in prior research regresses actual measures on reported values using an external validation dataset, and then uses the estimated coefficients to predict actual measures in the primary dataset. This approach requires the strong assumption that the expectations of measured weight and height conditional on the reported values are the same in both datasets. In contrast, we use percentile ranks rather than levels of reported weight and height. Our approach requires the weaker assumption that the conditional expectations of actual measures are increasing in reported values in both samples. This makes our correction more robust to differences in measurement error across surveys as long as both surveys represent the same population. We examine three nationally representative datasets and find that misreporting appears to be sensitive to differences in survey context. When we compare predicted BMI distributions using the two validation approaches, we find that the standard correction is affected by differences in misreporting while our correction is not. Finally, we present several examples that demonstrate the potential importance of our correction for future econometric analyses and estimates of obesity rates.     

Association of the ins/del polymorphisms of uncoupling protein 2 (UCP2) with BMI in a Korean population

To elucidate the potential impact of the variants of the UCP2 gene on obesity phenotypes, we have genotyped four polymorphisms in UCP2 among 988 Korean subjects using TaqMan^® methods, and three common haplotypes with frequency greater than 0.1 were constructed in the Korean population. No significant associations were detected with the risk of metabolic syndrome by logistic regression analyses. However, the 45 base-pair ins/del polymorphism (+3474 ins/del) in the 3′ untranslated region (3′ UTR) showed significant association with body mass index (P = 0.007, P^corr = 0.02) and waist circumference (P = 0.005). Further subgroup analysis revealed that the genetic effects were more apparent among female subjects. In addition, a summary of the controversial genetic effects on obesity mediated by UCP2 polymorphisms from previous studies is also given. Our results suggest that subjects with a 45 bp insertion allele of UCP2+3474 ins/del might have a higher risk of developing obesity, although the biological effects of this variant are not completely known.     

生化指标与2 型糖尿病患者实验诊断及预后相关性研究

目的：研究BMI、HbA1c、病程、相关代谢指标与2 型糖尿病（T2DM）诊断及预后的关系。方法：收集379 例T2DM 患者与383 例健康体检者,采用生化分析仪分析二组人群的生化指标,采用高效液相色谱法检测T2DM 组HbA1c 水平,胰岛素及C 肽采用电化学发光法检测。计量资料采用t 检验、单因素方差及相关性分析,计数资料采用卡方检验分析。结果：对各组结果进行比较显示（1）T2DM 患者的BMI、FBG、TG、LDL-C、BUN、UA、HbA1c 水平明显高于正常对照组（P均<0.01),HDL-C、CREA 水平明显低于对照组（P均<0.01);（2 ）TC、LDL-C、BUN、CREA及2hINS 与年龄相关。（3）肥胖组的TG、CREA、UA、FCP、2hCP 高于非肥胖组（P 均<0.05);（4 ）初诊T2DM 患者的FBG、TG、HbAlc、LDL-C 水平明显高于5 年以上患者（P均<0.05),而HDL-C 低于5 年以上患者（P<0.05);（5 ）HbA1c≥ 11%组的FBG水平明显高于HbA1c≤ 8%及HbA1c＝8～11%组（P<0.01）,而UA、FINS、FCP、2hINS、2hCP 水平明显低于HbA1c<8%组（P 均<0.01);FBG、TG 与HbA1c 水平呈正相关（P<0.05）;FINS、FCP、2hINS、2hCP、UA与HbA1c 水平呈负相关（P<0.01);结论：BMI、FBG、TG、LDL-C、BUN、UA、HDL-C、CREA均可作为T2DM诊断的参考指标。其中LDL-C、BUN、CREA、2hINS 指受年龄影响。TG、CREA、UA、FCP(空腹C-肽）、2hCP与肥胖相关。FBG、TG、HbAlc、LDL-C、HDL-C与病程相关;FBG、TG、HbA1c、FINS、FCP、2hINS、2hCP、UA与HbA1c 相关。     

生化指标与2型糖尿病患者实验诊断及预后相关性研究

目的：研究BMI、HbA1c、病程、相关代谢指标与2型糖尿病（T2DM）诊断及预后的关系。方法：收集379例T2DM患者与383例健康体检者,采用生化分析仪分析二组人群的生化指标,采用高效液相色谱法检测T2DM组HbA1c水平,胰岛素及C肽采用电化学发光法检测。计量资料采用t检验、单因素方差及相关性分析,计数资料采用卡方检验分析。结果：对各组结果进行比较显示（1）T2DM患者的BMI、FBG、TG、LDL-C、BUN、uA、HbA1c水平明显高于正常对照组（P均〈0．01）,HDL-C、CREA水平明显低于对照组（P均〈0．01）;（2）TC、LDL—C、BUN、CREA及2hINS与年龄相关。（3）肥胖组的TG、CREA、UA、FCP、2hCP高于非肥胖组（P均〈0．05）;（4）初诊T2DM患者的FBG、TG、HbA1c、LDL-C水平明显高于5年以上患者（P均〈0．05）,而HDL-c低于5年以上患者（P〈0．05）;（5）HbA1c≥11％组的FBG水平明显高于HbA1c≤8％及HbA1c=8-11％组（P〈0．01）,而UA、FINS、FCP、2hINS、2hCP水平明显低于HbA1c〈8％组（P均〈0．01）;FBG、TG与HbA1c水平呈正相关（P〈0．05）;FINS、FCP、2hINS、2hCP、UA与HbA1c水平呈负相关（P〈0．01）;结论：BMI、FBG、TG、LDL-C、BUN、UA、HDL-C、CREA均可作为T2DM诊断的参考指标。其中LDL—C、BUN、CREA、2hINs指受年龄影响。TG、CREA、uA、FCP（空腹C-肽）、2hCP与肥胖相关。FBG、TG、HbA1c、LDL-C、HDL-C与病程相关;FBG、TG、HbA1c、FINS、FCP、2hINS、2hCP、UA与HbA1c相关。     

Fat, muscles, and wages

Recent studies in health economics have generated two important findings: that as a measure of fatness the body mass index (BMI) is biased; and that, when it comes to analyzing wage correlates, both fat-free mass (FFM) and body fat (BF) are better suited to the task. We validate these findings for Germany using the BIAdata Base Project and the German Socio-Economic Panel. While we find no significant correlation between BMI and wages in any of our models, simple linear regression models featuring both contemporary and time-lagged fatness measures indicate that FFM and, to a lesser extent, BF are associated with hourly wages: more specifically, the relationship between FFM/BF and hourly wages is about two to three times higher for females than for males. In contrast, fixed-effects models indicate that there is no correlation between hourly wages and both FFM and BF with one exception: a significant correlation (and one in line with expectations) is found to be the rule among job changers.