Binyan Wang

Efficacy of Folic Acid Therapy in Primary Prevention of Stroke Among Adults With Hypertension in China: The CSPPT Randomized Clinical Trial

IMPORTANCE Uncertainty remains about the efficacy of folic acid therapy for the primary prevention of stroke because of limited and inconsistent data. OBJECTIVE To test the primary hypothesis that therapy with enalapril and folic acid is more effective in reducing first stroke than enalapril alone among Chinese adults with hypertension. DESIGN, SETTING, AND PARTICIPANTS The China Stroke Primary Prevention Trial, a randomized, double-blind clinical trial conducted from May 19, 2008, to August 24, 2013, in 32 communities in Jiangsu and Anhui provinces in China. A total of 20,702 adults with hypertension without history of stroke or myocardial infarction (MI) participated in the study. INTERVENTIONS Eligible participants, stratified by MTHFR C677T genotypes (CC, CT, and TT), were randomly assigned to receive double-blind daily treatment with a single-pill combination containing enalapril, 10 mg, and folic acid, 0.8 mg (n = 10,348) or a tablet containing enalapril, 10 mg, alone (n = 10,354). MAIN OUTCOMES AND MEASURES The primary outcome was first stroke. Secondary outcomes included first ischemic stroke; first hemorrhagic stroke; MI; a composite of cardiovascular events consisting of cardiovascular death, MI, and stroke; and all-cause death. RESULTS During a median treatment duration of 4.5 years, compared with the enalapril alone group, the enalapril-folic acid group had a significant risk reduction in first stroke (2.7% of participants in the enalapril-folic acid group vs 3.4% in the enalapril alone group; hazard ratio [HR], 0.79; 95% CI, 0.68-0.93), first ischemic stroke (2.2% with enalapril-folic acid vs 2.8% with enalapril alone; HR, 0.76; 95% CI, 0.64-0.91), and composite cardiovascular events consisting of cardiovascular death, MI, and stroke (3.1% with enalapril-folic acid vs 3.9% with enalapril alone; HR, 0.80; 95% CI, 0.69-0.92). The risks of hemorrhagic stroke (HR, 0.93; 95% CI, 0.65-1.34), MI (HR, 1.04; 95% CI, 0.60-1.82), and all-cause deaths (HR, 0.94; 95% CI, 0.81-1.10) did not differ significantly between the 2 treatment groups. There were no significant differences between the 2 treatment groups in the frequencies of adverse events. CONCLUSIONS AND RELEVANCE Among adults with hypertension in China without a history of stroke or MI, the combined use of enalapril and folic acid, compared with enalapril alone, significantly reduced the risk of first stroke. These findings are consistent with benefits from folate use among adults with hypertension and low baseline folate levels. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00794885.

An extreme-sib-pair genome scan for genes regulating blood pressure.

Hypertension, a risk factor for many cardiovascular, cerebrovascular, and renal diseases, affects one in four Americans, at an annual cost of>

A genome-wide scan for loci linked to forearm bone mineral density

30 billion. Although genetic mutations have been identified in rare forms of hypertension, including Liddle syndrome and glucocorticoid-remediable aldosteronism, the abundance of plausible candidate genes and potential environmental risk factors has complicated the genetic dissection of more prevalent essential hypertension. To search systematically for chromosomal regions containing genes that regulate blood pressure, we scanned the entire autosomal genome by using 367 polymorphic markers. Our study population, selected from a blood-pressure screen of >200,000 Chinese adults, comprises rare but highly efficient extreme sib pairs (207 discordant, 258 high concordant, and 99 low concordant) and all but a single parent of these sibs. By virtue of the sampling design, the number of sib pairs, and the availability of genotyped parents, this study represents one of the most powerful of its kind. Although no regions achieved a 5% genomewide significance level, maximum LOD-score values were >2.0 (unadjusted P<.001) for regions containing five markers (D3S2387, D11S2019, D15S657, D16S3396, and D17S1303), in our primary analysis. Other promising regions identified through secondary analyses include loci near D4S3248, D7S2195, D10S1423, D20S470, D20S482, D21S2052, PAH, and AGT.

Serum DDT, age at menarche, and abnormal menstrual cycle length

Abstract Osteoporosis is a chronic disorder characterized by low bone mass and fragility fractures. It affects more than 25 million men and women in the United States alone. Although several candidate genes, such as the vitamin-D-receptor gene or the estrogen-receptor gene, have been suggested in the pathogenesis of osteoporosis, the genetic dissection of this disorder remains a daunting task. To search systematically for chromosomal regions containing genes that regulate bone mineral density (BMD), we scanned the entire autosomal genome by using 367 polymorphic markers among 218 individuals (153 sibpairs) from 96 nuclear families collected from three townships of Anqing, China. In these 96 families, DNA samples from both parents were available for 82 (85.4%) families. By using age- and gender-adjusted forearm BMD measurements, a peak on chromosome 2 near D2S2141, D2S1400, and D2S405, a region previously linked to spinal BMD, showed evidence of linkage to both proximal and distal forearm BMD (multipoint LOD=2.15 and 2.14 for proximal and distal forearm BMD, respectively). One region on chromosome 13 (multipoint LOD=1.67) in the proximity of D13S788 and D13S800 showed evidence of linkage to distal forearm BMD only. Possible candidate genes included CALM2 (calmodulin 2) at 2p21.3-p21.1, a putative STK (serine/threonine kinase) at 2p23–24, POMC (pro-opiomelanocortin) at 2p23.3, and COL4A1 and COL4A2 (collagen IV alpha-1 and alpha-2 subunits) at 13q34. Because of the limited sample size, the suggestive evidence of linkage of this study should be considered as tentative and needs to be replicated in other larger populations.

Precise and Continuous Time and Frequency Synchronisation at the 5×10-19 Accuracy Level

Background: Although dichlorodiphenyl trichloroethane (DDT) exposure is known to affect human endocrine function, few previous studies have investigated the effects of DDT exposure on age at menarche or menstrual cycle length. Methods: A cross sectional study was conducted to study the effects of DDT exposure on age at menarche and menstrual cycle length among 466 newly married, nulliparous female Chinese textile workers aged 20–34 years enrolled between 1996 and 1998. Serum was analysed for DDT and its major metabolites. Multivariate linear regression was used to estimate DDT exposure effects on age at menarche and multivariate logistic regression was used to estimate DDT exposure effects on odds of experiencing short or long cycles. Results: Relative to those in the lowest DDT quartile, the adjusted mean age at menarche was younger in those in the fourth quartile (−1.11 years). Modeled as a continuous variable, a 10 ng/g increase in serum DDT concentration was associated with an adjusted reduction in age at menarche of 0.20 years. Relative to those in the lowest DDT quartile, odds of any short cycle (<21 days) in the previous year were higher for those in the fourth quartile (odds ratio = 2.78; 95% CI 1.07 to 7.14). There were no associations between serum DDT concentrations and odds of experiencing a long cycle (>40 days). Conclusion: Results suggest that DDT exposure was associated with earlier age at menarche and increased risk of experiencing a shortened menstrual cycle.

A Genomewide Search for Quantitative-Trait Loci Underlying Asthma

The synchronisation of time and frequency between remote locations is crucial for many important applications. Conventional time and frequency dissemination often makes use of satellite links. Recently, the communication fibre network has become an attractive option for long-distance time and frequency dissemination. Here, we demonstrate accurate frequency transfer and time synchronisation via an 80 km fibre link between Tsinghua University (THU) and the National Institute of Metrology of China (NIM). Using a 9.1 GHz microwave modulation and a timing signal carried by two continuous-wave lasers and transferred across the same 80 km urban fibre link, frequency transfer stability at the level of 5×10−19/day was achieved. Time synchronisation at the 50 ps precision level was also demonstrated. The system is reliable and has operated continuously for several months. We further discuss the feasibility of using such frequency and time transfer over 1000 km and its applications to long-baseline radio astronomy.

Leptin concentrations in relation to overall adiposity, fat distribution, and blood pressure in a rural Chinese population

A genomewide screen for quantitative-trait loci (QTLs) that underlie asthma was performed on 533 Chinese families with asthma, by the unified Haseman-Elston method. Nine asthma-related phenotypes were studied, including forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), airway responsiveness as indicated by methacholine (MTCH)-challenge test, serum total immunoglobulin E (TIgE), serum-specific immunoglobulin E, eosinophil count in peripheral blood, and skin-prick tests with three different allergens (cockroach, Dermatophagoides pteronyssinus, and D. farinae). Our study showed significant linkage between airway responsiveness to MTCH and D2S1780 on chromosome 2 (P<.00002) and provided suggestive evidence (P<.002) for six additional possible QTLs: D10S1435 and D22S685, for FEV1; D16S412, for FVC; D19S433, for airway responsiveness to MTCH; D1S518, for TIgE; and D4S1647, for skin reactivity to cockroach. No significant or suggestive evidence of linkage for the other four traits was found.

Folic acid supplementation and cancer risk: A meta-analysis of randomized controlled trials

OBJECTIVE: : To examine the associations between leptin levels and body mass index (BMI), fat distribution (reflected by waist to hip ratio and skinfold measurements), and blood pressure in a rural Chinese population.DESIGN AND SUBJECTS: A cross-sectional study of 294 participants who provided blood samples.MEASUREMENTS: Plasma concentrations of leptin, BMI, waist to hip ratio, skinfold thickness, and blood pressure.RESULTS: The average leptin concentration was 5.2 µg/l (3.1 for men and 7.3 for women). In univariate analyses, leptin levels were significantly correlated with BMI (r=0.47), abdominal skinfold thickness (r=0.53), triceps skinfold thickness (r=0.56), waist circumference (r=0.41), hip circumference (r=0.51), waist to hip ratio (r=0.17), and diastolic blood pressure (r=0.13). In multivariate analyses controlling for age, sex, education, current smoking, and alcohol use, independent associations between leptin levels and BMI, waist to hip ratio, waist circumference, and abdominal skinfold thickness remained. However, the significant association between leptin and blood pressure disappeared after adjusting for BMI, whereas the association between BMI and blood pressure persisted after adjusting for leptin level.CONCLUSIONS: We observed a strong positive relationship between overall adiposity and leptin levels in both men and women in a rural Chinese population. In addition, leptin concentrations were significantly associated with central obesity measured by waist to hip ratio and abdominal skinfold, independent of overall obesity. The observed positive association between leptin and blood pressure was largely explained by BMI.

Heritability and Environmental Factors Affecting Vitamin D Status in Rural Chinese Adolescent Twins

There are growing data and a continuing controversy over the effect of folic acid supplementation on cancer risk. We conducted a meta‐analysis based on up‐to‐date published relevant randomized trials to further examine this issue. Relative risk (RR) was used to measure the effect of folic acid supplementation on risk of cancer using a random‐effects model. Overall, folic acid supplementation had no significant effect on total cancer incidence (13 trials, n = 49,406, RR = 1.05; 95% CI: 0.99–1.11, p = 0.13), colorectal cancer (seven trials, n = 33,824, 1.01; 0.82–1.23, p = 0.95), other gastrointestinal cancer (two trials, n = 20,228, 1.00; 0.75–1.33, p = 0.99), prostate cancer (five trials, n = 27,065, 1.17; 0.84–1.62, p = 0.35), other genitourinary cancer (two trials, n = 20,228, 0.97; 0.75–1.27, p = 0.84), lung cancer (five trials, n = 31,864, 1.00; 0.84–1.21, p = 0.97), breast cancer (four trials, n = 19,800, 0.82; 0.63–1.07, p = 0.15), hematological malignancy (three trials, n = 25,670, 0.87; 0.64–1.17, p = 0.35) and total cancer mortality (six trials, n = 31,930, 1.02; 0.90–1.15, p = 0.81). However, a significantly reduced risk was observed for melanoma (three trials, n = 19,128, 0.47; 0.23–0.94, p = 0.03). Furthermore, higher total cancer incidence risk was observed among those trials with a higher percent use of lipid‐lowering drugs (>60%, 1.10; 1.00–1.20, p = 0.04), or with lower percent baseline hypertension (≤70%, 1.08; 1.00–1.16, p = 0.057).Consistently, meta‐regression analyses suggested that the similar trend between percent use of lipid‐lowering drugs (p = 0.084) or percent baseline hypertension (p = 0.056) and log‐RR for total cancer incidence associated with folic acid supplementation. Our findings indicate that folic acid supplementation has no significant effect on total cancer incidence, colorectal cancer, prostate cancer, lung cancer, breast cancer or hematological malignancy, but reduces the risk of melanoma.

Genetic and Environmental Contributions to Phenotypic Components of Metabolic Syndrome: A Population-based Twin Study

CONTEXT Factors associated with the high prevalence of vitamin D deficiency in China are not well described, especially among Chinese adolescents. OBJECTIVES The aim of the study was to examine important environmental or sociodemographic factors influencing 25-hydroxyvitamin D [25(OH)D] levels and estimate its heritability. DESIGN A sample of 226 male and female adolescent twins aged 13-20 yr from a large prospective twin cohort of rural Chinese children and adolescents that has been followed for 6 yr were evaluated. MAIN OUTCOME MEASURE(S) Blood level of 25(OH)D was measured using tandem mass spectrometry methodology. RESULTS The overall mean (SD) 25(OH)D level was 18.0 (9.4) ng/ml, with wide variation by gender and season. In males (47.4% of subjects), the mean (SD) 25(OH)D level was 12.1 (4.2) ng/ml in non-summer and 27.4 (8.8) ng/ml in summer; in females, it was 10.1 (4.1) ng/ml in non-summer and 19.5 (6.3) ng/ml in summer. A multivariate model that included gender, age, season, physical activity, and student status demonstrated that male gender, summer season, and high physical activity significantly increased 25(OH)D levels. Summer season and male gender also significantly decreased the risk of being in the lowest 25(OH)D tertile. Overall, 68.9% of the variability in 25(OH)D level was attributable to additive genetic influence. Stratification by gender found that in males, 85.9% of the variability in 25(OH)D level was attributable to such influence, but in females, it was only 17%. CONCLUSION In this sample of rural Chinese adolescents, 25(OH)D level was influenced by gender, season, and physical activity level. There was a strong genetic influence on 25(OH)D level in males only.