Testosterone concentrations in young healthy US versus Chinese men.

BACKGROUND: Previous small studies examining differences in testosterone concentrations by ethnicity found mixed results for Caucasians and Chinese men, which might be confounded by age differences and living standards. The aim of the present study is to examine the differences in total, free, and bioavailable testosterone concentrations between healthy young men from the United States (US) and from the most economically developed part of China, i.e., Hong Kong (HK). METHODS: Cross-sectional analysis based on 365 young men from the Third National Health and Nutrition examination Survey (NHANES III) in the US and 299 Chinese men recruited from university students. All participants were aged from 18 to 29 years. Main outcome measures were total testosterone (TT) and calculated bioavailable testosterone (Bio T) and free testosterone (FT). RESULTS: In both US and Chinese men, TT, FT, and Bio T concentration peaked at 20-24 years of age, at 23.19, 0.49, and 12.23 nmol/l in US men, and 20.72, 0.48 and 12.59 nmol/l in Chinese men, respectively. Among those aged 18-24 years, after adjusting for age, US men had higher TT (mean, 95% confidence interval: 21.64, 21.31-21.99 versus 20.20, 20.12-20.28 nmol/l), but not FT (0.47, 0.47-0.48 versus 0.47, 0.47-0.47 nmol/l) or Bio T (11.90, 11.83-11.97 versus 12.39, 12.35-12.42 nmol/l) than Chinese men. CONCLUSIONS: TT, but not FT or Bio T concentrations are lower in young healthy Chinese men than US men. These differences apparent in young men may be important in understanding different patterns of diseases between Western and Asian populations.

Intergenerational influences on diabetes in a developing population: the Guangzhou Biobank Cohort Study.

OBJECTIVES: Intergenerational "mismatch" and/or growth conditions may be relevant to the epidemic of diabetes in developing populations. In a rapidly developing southern Chinese population, we tested whether maternal environment, proxied by maternal literacy, or family socio-economic position (SEP), proxied by paternal literacy, were associated with fasting glucose and diabetes. To assess if intergenerational mismatch contributed, we tested whether the associations varied by life course SEP. METHODS: In 19,818 older (≥50 years) adults from the Guangzhou Biobank Cohort Study (phases 2 and 3), we used censored and logistic regression to assess the associations of maternal and paternal literacy with fasting glucose, elevated fasting glucose and diabetes and whether these associations varied by sex, age or life course SEP. RESULTS: Maternal, but not paternal, literacy was negatively associated with fasting plasma glucose (ß-coefficient -0.06 mmol/l, 95% confidence interval (CI) -0.11 to -0.01) and elevated fasting glucose (odds ratio (OR) 0.92, 95% CI 0.86-0.99) adjusted for age, sex, study phase, life course SEP, childhood growth, adiposity, number of offspring, and birth order. Associations of maternal and paternal literacy with fasting glucose, elevated fasting glucose and diabetes did not vary by sex, age or life course SEP. CONCLUSION: Offspring of literate mothers had lower risk for impaired glucose tolerance than offspring of illiterate mothers. Being raised by literate mothers may increase the likelihood of children with higher SEP and lower long-term disease risk, or better maternal conditions over generations may be associated with lower fasting glucose.

Report on the second Asia Autoimmunity Forum 3-5 March 2006, Hong Kong.

On March 3-5, 2006, The HK Society of Rheumatology, University of Hong Kong and Singapore National Arthritis Foundation organized the second Asia Autoimmunity Forum (AAF) in Hong Kong which was attended by over 200 delegates from around Asia. More than 20 invited international and regional experts in the field of autoimmune rheumatic diseases spoke on topics including the pathogenetic mechanisms, clinical aspects and novel therapeutic approaches of autoimmune rheumatic diseases. There were 8 plenary lectures and 4 symposia and the AAF provided an excellent avenue to promote the co-ordination and knowledge exchange in the area of autoimmune rheumatic diseases in Asia.

Genetically predicted 17ß-estradiol and systemic inflammation in women: a separate-sample Mendelian randomisation analysis in the Guangzhou Biobank Cohort Study.

BACKGROUND: Many chronic diseases are characterised by low-grade systemic inflammation. Oestrogens may promote immune response consistent with sex-specific patterns of diseases. In vitro culture and animal experiments suggest oestrogens are anti-inflammatory and might thereby protect against low-grade systemic inflammation. Evidence from epidemiological studies is limited. Using a Mendelian randomisation analysis with a separate-sample instrumental variable (SSIV) estimator, we examined the association of genetically predicted 17ß-estradiol with well-established systemic inflammatory markers (total white cell count, granulocyte and lymphocyte count). METHODS: A genetic score predicting 17ß-estradiol was developed in 237 young Chinese women (university students) from Hong Kong based on a parsimonious set of genetic polymorphisms (ESR1 (rs2175898) and CYP19A1 (rs1008805)). Multivariable linear regression was used to examine the association of genetically predicted 17ß-estradiol with systemic inflammatory markers among 3096 older (50+ years) Chinese women from the Guangzhou Biobank Cohort Study. RESULTS: Predicted 17ß-estradiol was negatively associated with white blood cell count (-6.3 10(3)/mL, 95% CI -11.4 to -1.3) and granulocyte count (-4.5 10(3)/mL, 95% CI -8.5 to -0.4) but not lymphocyte count (-1.5 10(3)/mL, 95% CI -3.4 to 0.4) adjusted for age only. Results were similar further adjusted for education, smoking, use of alcohol, physical activity, Body Mass Index, waist-hip ratio, age of menarche, age at menopause, use of hormonal contraceptives and hormone replacement therapy. CONCLUSIONS: Endogenous genetically predicted 17ß-estradiol reduced low-grade systemic inflammatory markers (white blood cell count and granulocyte count), consistent with experimental and ecological evidence of 17ß-estradiol promoting immune response. Replication in a larger sample is required.

Pathways to obesity in a developing population: The Guangzhou Biobank Cohort Study.

BACKGROUND: 'Environmental mismatch' may contribute to obesity in rapidly developing societies, because poor early life conditions could increase the risk of obesity in a subsequently more socio-economically developed environment. In a recently developing population (from southern China) we examined the association of life-course socio-economic position (SEP) with obesity. METHODS: In a cross-sectional study of 9998 adults from the Guangzhou Biobank Cohort Study (phase 2) examined in 2005-06, we used multivariable linear regression to assess the association of SEP at three life stages (proxied by parental possessions, education and longest held occupation) with obesity [body mass index (BMI) and waist-hip ratio (WHR)] in men and women. RESULTS: There was no evidence that socio-economic position trajectory had supra-additive effects on BMI or WHR. Instead in women, higher SEP at any life stage usually contributed to lower BMI and WHR; e.g. women with higher early adult SEP had lower BMI [-0.45; 95% confidence interval (CI) -0.71 to -0.19) and WHR (-0.02; 95% CI -0.02 to -0.012]. In contrast, in men, higher childhood SEP was associated with higher BMI (0.53; 95% CI 0.18 to 0.88) and WHR (0.01; 95% CI 0.003 to 0.02) as was high late adulthood SEP with BMI (0.36; 95% CI 0.07 to 0.64). CONCLUSIONS: This study provides little support for environmental mismatch over the life course increasing obesity in this rapidly transitioning southern Chinese population. However, our findings highlight different effects of the epidemiologic transition in men and women, perhaps with pre-adult exposures as a critical window for sex-specific effects.