Prolonged time to pregnancy in residents exposed to ionising radiation in cobalt-60-contaminated buildings.

OBJECTIVES: Radiation-induced cytogenetic damage in somatic cells has raised concern that low-dose ionising radiation can also damage germ cells and influence gamete production and/or function, resulting in decreased fertility. Time to pregnancy (TTP) was used to investigate whether exposure to gamma-radiation affected fertility among the residents of cobalt-60-contaminated buildings in Taiwan. METHODS: This was a retrospective pregnancy-based study of 357 pregnancies born to 124 exposed couples. Both the cumulative dose and the dose rate for each pregnancy was estimated based on a physical dose reconstruction programme. The comparison population consisted of 612 pregnancies born to 225 couples randomly sampled from the Taiwan general population. Information on TTP was collected by personal interviews. Fecundability ratios (FRs) were calculated with a discrete proportional hazards model. RESULTS: For exposed mothers, fertility decreased significantly when unprotected intercourse began during the period of living in the radiation-contaminated buildings (FR 0.75, 95% CI 0.61 to 0.92). The effect was borderline significant for fathers (FR 0.83, 95% CI 0.68 to 1.02). There was evidence that prolonged TTP was associated with the rate of exposure for both mothers and fathers (tests for trend: female, p=0.0006; male, p=0.03), especially evident for dose rates > or =10 mSv/year (female, FR 0.60, 95% CI 0.43 to 0.84; male, FR 0.68, 95% CI 0.49 to 0.96). CONCLUSIONS: Our findings suggest that exposure to low-dose ionising radiation of cobalt-60-contaminated buildings may decrease fertility, especially in females. Fertility declined with increasing concurrent dose but not with cumulative dose.

Neutron reflectivity study of the complexation of DNA with lipids and surfactants at the surface of water.

Complexation of lipids and surfactants with short DNA fragments at the air-water interface has been studied by neutron reflectivity. Complexation with zwitterionic lipids occurs in the presence of divalent cations, and ion specificity has been demonstrated (binding is less effective with Ba2+ than with Mg2+ or Ca2+). One and two DNA layers have been observed for dilute and more compact lipid monolayers, respectively. Two DNA layers have also been found with the soluble cationic surfactant dodecyltrimethylammonium bromide (DTAB), except close to the precipitation boundary. This result is opposite to that found in ellipsometry where very thick layers are found in this region. It is possible that the ellipsometry signal is due to highly hydrated bulk complexes adsorbing at the surface, not seen by neutrons because of unfavorable contrast conditions. Long DNA was found to be less keen to form surface complexes than short DNA fragments.

Obesity and hepatitis B infection are associated with increased risk of metabolic syndrome in university freshmen.

OBJECTIVE: To investigate the prevalence of metabolic syndrome and its associated risk factors in a cohort of university freshmen. DESIGN: A cross-sectional study in a university health center in North Taiwan. SUBJECTS: A total of 8226 students (mean age: 19.2+/-2.3 years) receiving pre-entrance health examinations and lifestyle questionnaires during the 2005-2006 academic year were recruited. MEASUREMENTS: A fasting plasma glucose, lipids, uric acid and hepatitis B serology were measured for each subject. The prevalence of metabolic syndrome and its individual components were examined using the America Heart Association and National Heart Lung Blood Institute criteria. The risk factors for metabolic syndrome were identified using a multivariate logistic regression analysis. RESULTS: The prevalence of overweight, obesity and metabolic syndrome was 12.7% (17.0% in men and 7.6% in women), 13.0% (18.4% in men and 6.4% in women) and 4.6% (6.4% in men and 2.4% in women). The risk for metabolic syndrome increased with an increase of body mass index and plasma uric acid level, and decreased with the vigorous physical activity and current alcohol drinking. Furthermore, as compared to subjects with seroprotective titers from hepatitis B vaccination (anti-HBs(+) and anti-HBc(-)), those without protective titers of anti-HBs after vaccination or without hepatitis B infection (anti-HBs(-) and anti-HBc(-)) had 34% higher risk for metabolic syndrome, and those with natural infection of hepatitis B (anti-HBc(+)) had 58% higher risk for metabolic syndrome. CONCLUSIONS: Overweight, obesity and metabolic syndrome were more common among men than women in university freshmen. Hepatitis B vaccination with anti-HBs(+) was associated with a lower risk of metabolic syndrome as compared to anti-HBs(-). However, hepatitis B infection presented with anti-HBc(+) was associated with a higher risk of metabolic syndrome. The interplay between hepatitis B infection, hepatitis B vaccination and metabolic syndrome needs further investigation.

Insulin resistance, obesity, and metabolic syndrome among non-diabetic pre- and post-menopausal women in North Taiwan.

OBJECTIVE: To investigate the relationship between the metabolic syndrome and its related factors among non-diabetic pre- and post-menopausal women in North Taiwan. DESIGN: A cross-sectional study in a medical center in North Taiwan. SUBJECTS: Five hundred and ninety-four, non-diabetic middle-aged women (age range=40-64 years, mean=48.9+/-5.4 years) were recruited. MEASUREMENTS: The fasting plasma glucose, insulin, lipids levels and anthropometric indices were measured. The homeostasis model assessment was applied to estimate the degree of insulin resistance (HOMA-IR). Metabolic syndrome was defined by using the National Cholesterol Education Panel (NCEP) criteria and modified NCEP criteria (waist circumference >80 cm). RESULTS: The prevalence of metabolic syndrome was 6.2% using NCEP criteria, and 8.9% using modified NCEP criteria. Post-menopausal women had a higher prevalence of metabolic syndrome and its individual components compared to pre-menopausal women except hyperglycemia and low HDL-C. In multiple logistic regression analysis with adjustment for age and menopausal status, both BMI and HOMA-IR were independently associated with the metabolic syndrome. CONCLUSION: The prevalence of metabolic syndrome was higher in post-menopausal than pre-menopausal women. Both obesity and insulin resistance may play an important role in the development of metabolic syndrome among the middle-aged women in North Taiwan.

Plasma leptin is associated with insulin resistance independent of age, body mass index, fat mass, lipids, and pubertal development in nondiabetic adolescents.

OBJECTIVE: The rising epidemic worldwide in overweight and obese children requires urgent attention. Leptin has been found to be associated with body weight control and possibly affects insulin sensitivity. Since insulin resistance is associated with obesity in adults and possibly in adolescents, we set out to investigate the association of plasma leptin level with various anthropometric indices, body fat mass (FM), lipids, and insulin resistance (IR) index in nondiabetic adolescents. DESIGN: A cross-sectional study from three high schools in Taipei City in Taiwan. SUBJECTS: A total of 402 nondiabetic subjects (162 boys and 240 girls; age range, 10-19 y; mean age, 15.8+/-1.9 y, and mean body mass index (BMI), 24.8+/-4.6 kg/m(2)) were recruited. MEASUREMENTS: The fasting plasma leptin, plasma glucose, insulin, lipids, and anthropometric indices including height, weight, waist (WC) and hip circumferences, and waist-to-hip ratio (WHR) were examined. Total body FM and percentage body fat (FM%) were obtained from dual-energy X-ray absorptiometry. The homeostasis model was applied to estimate the degree of IR. RESULTS: The plasma leptin levels were significantly higher in girls (17.45+/-10.13 ng/ml) than boys (8.81+/-6.71 ng/ml, P<0.001). The plasma leptin levels were positively correlated to BMI, WC, WHR, FM, FM%, and triglycerides (TG). The IR index was positively correlated to BMI, WC, WHR, FM, FM%, TG, and leptin. Using the multivariate linear regression models, we found that plasma leptin remains significantly associated with IR index even after adjusting for age, gender, BMI, FM, WC, Tanner stage, and TG. CONCLUSION: Plasma leptin was associated with IR index independent of age, gender, BMI, FM, WC, Tanner stage, and TG. Plasma leptin levels in adolescents could be a predictor for the development of the metabolic syndrome disorders and cardiovascular diseases.

Assessing progression and efficacy of treatment for diabetic retinopathy following the proliferative pathway to blindness: implication for diabetic retinopathy screening in Taiwan.

AIMS: The natural history and treatment efficacy of diabetic retinopathy (DR) play important roles in the evaluation of screening. Therefore, the natural history of DR and rates of transition after treatment (including metabolic control and laser photocoagulation) from no diabetic retinopathy (NDR) to blindness were quantified. METHODS: We studied a cohort of 795 patients with diabetes mellitus (DM) receiving fundus examination in the ophthalmology out-patient department of one medical centre between 1 January 1990 and 31 December 1992 in Taiwan. Follow-up data until 31 December 1998 were collected by chart review. Two multistate Markov models were proposed to assess the efficacy of the treatment regime in reducing progression to blindness. RESULTS: The average times spent in states (i) no diabetic retinopathy (NDR), (ii) background diabetic retinopathy (BDR), (iii) preproliferative diabetic retinopathy (PPDR), and (iv) proliferative retinopathy (PDR) were 10.86 years, 8.33 years, 1.67 years, and 2.17 years, respectively. Early detection of PPDR may lead to a 60% reduction in PDR and an 83% reduction in blindness. Simulated results based on these parameters show that an annual screening programme, a biennial screening regime and a 4-yearly screening regime can lead to 54% (95% confidence interval (CI): 44-62%), 51% (95% CI: 41-59%), and 46% (95% CI: 36-54%) reductions in blindness, respectively. CONCLUSIONS: Assessing the progression of DR following the proliferative pathway in this study suggests that screening for DR is worthwhile and that a 4-year interscreening interval for patients as yet without DR may be justified.

Optimal cut-off values for obesity: using simple anthropometric indices to predict cardiovascular risk factors in Taiwan.

BACKGROUND: The increased health risks associated with obesity have been found to occur in Asians at lower body mass indices (BMIs). To determine the optimal cut-off values for overweight or obesity in Taiwan, we examined the relationships between four anthropometric indices and cardiovascular risk factors. METHODS: The data were collected from four health-screening centers from 1998 to 2000 in Taiwan. Included were 55 563 subjects (26 359 men and 29 204 women, mean age=37.3+/-10.9 and 37.0+/-11.1 y, respectively). None had known major systemic diseases or were taking medication. Individual body weight, height, waist circumference (WC), and a series of tests related to cardiovascular risk (blood pressure, fasting plasma glucose, triglycerides, total cholesterol, low- and high-density lipoprotein cholesterol) were assessed and their relationships were examined. Receiver operating characteristic (ROC) analysis was used to find out the optimal cut-off values of various anthropometric indices to predict hypertension, diabetes mellitus and dyslipidemia. RESULTS: Of the four anthropometric indices we studied, waist-to-height ratio (WHtR) in women was found to have the largest areas under the ROC curve (women=0.755, 95% CI 0.748-0.763) relative to at least one risk factor (ie hypertension or diabetes or dyslipidemia). The optimal cut-off values for overweight or obesity from our study in men and women showed that BMIs of 23.6 and 22.1 kg/m(2), WCs of 80.5 and 71.5 cm, waist-to-hip ratios (WHpR) of 0.85 and 0.76, and WHtR of 0.48 and 0.45, respectively, may be more appropriate in Taiwan. CONCLUSIONS: WHtR may be a better indicator for screening overweight- or obesity-related CVD risk factors than the other three indexes (BMI, WC and WHpR) in Taiwan. Our study also supported the hypothesis that the cut-off values using BMI and WC to define obesity should be much lower in Taiwan than in Western countries.

Four anthropometric indices and cardiovascular risk factors in Taiwan.

OBJECTIVE: To examine the relationships between four anthropometric measurements and cardiovascular risk factors in Taiwan. DESIGN: The data was collected from four nationwide health screen centers in Taiwan from 1998 to 1999. SUBJECTS: A total of 38 556 subjects: 18 280 men and 20 276 women, mean age=37.0+/-11.1 y. None had any known major systemic diseases or were currently on medication. MEASUREMENTS: Individual body weight, height, waist circumference (WC), and cardiovascular risk factors (blood pressure, fasting plasma glucose, triglycerides, total cholesterol level, low-density and high-density-lipoprotein cholesterol level) were assessed and their relationships were examined. RESULTS: In both sexes, with increasing body mass index (BMI), WC, WHpR (waist-to-hip ratio) and WHtR (waist-to-height ratio), there were significantly higher risks of hypertension, impaired fasting glucose, diabetes and dyslipidemia (P<0.001) in almost all age groups. In the age groups older than 65, however, the relationships were statistically inconsistent. CONCLUSIONS: In Taiwan, the four anthropometric indexes (BMI, WC, WHpR, WHtR) are closely related to cardiovascular risk factors.