The Effects of Long-Term High Water Iodine Levels in the External Environment on the Carotid Artery.

Iodine excess typically affects thyroid function in the human body and may damage carotid artery. Four investigation plots with different water iodine levels were selected in Shandong Province, China. These included a low, medium, and high iodine group and an iodine excess group whose water iodine content was < 10, 50-150, 150-300, and > 300 µg/L, respectively. Residents aged 20-65 years answered a questionnaire and underwent carotid artery ultrasonography, and their height, weight, and urinary iodine concentrations were measured. A total of 2026 individuals participated in the study. Urinary iodine concentration increased with increased water iodine levels. The medial thickening rate and intimal roughness rate in the iodine excess group were significantly higher than in the other three groups. After controlling for factors such as gender, age, and BMI, iodine excess remained as a risk factor for carotid intima-media thickening. Excess water iodine in the external environment is a risk factor for intima-media thickening of the carotid artery, suggesting that iodine excess may cause vascular injury and promote atherosclerosis.

Effects of long-term excessive iodine intake on blood lipids in Chinese adults: a cross-sectional study.

OBJECTIVE: The aim of this study was to evaluate the effects of long-term excessive iodine intake on blood lipids in adults. METHODS: Three counties from Dezhou city and Liaocheng city in the Shandong province of China were selected as survey locations. Three to five villages were selected from each county and then categorized by the iodine concentration detected in the groundwater into Low (<10 µg/L), Medium (10-150 µg/L), High (150-300 µg/L), and Excessive (>300 µg/L) groups. A self-reported questionnaire was completed by each subject to provide demographic characteristics. Body height, weight, and blood pressure were recorded by trained staff. Blood lipids were measured. RESULTS: A total of 2156 subjects were recruited for the final analysis. The serum triglyceride (TRIG) was significantly higher in the Excessive group than in the other three groups (P < 0.05). Total cholesterol (TCHOL) and low-density lipoprotein-cholesterol (LDL-C) showed downward trends with the increases in the water iodine concentration. A statistical significance of the crude correlation coefficient was detected between the water iodine concentration and the TRIG, TCHOL, or LDL-C (P < 0.05). A significant correlation was also noted between the water iodine concentration and TCHOL or LDL-C after adjustment for covariates. High iodine concentration was a significant protective factor for TCHOL and LDL-C in adults, whereas elevated BMI and advancing age were risk factors for both variables. CONCLUSION: An association was identified between iodine excess and low TCHOL or LDL-C. In areas with excessive iodine, iodine intake should be considered in studies examining the factors that influence blood lipids.

Anthropometry-based 24-h urinary creatinine excretion reference for Chinese children.

To establish 24-h urinary creatinine excretion reference ranges based on anthropometry in healthy Chinese children, a cross-sectional survey was conducted using twice-sampled 24-h urine and anthropometric variables. Age- and sex-specific 24-h creatinine excretion reference ranges (crude and related to individual anthropometric variables) were derived. During October 2013 and May 2014, urine samples were collected. Anthropometric variables were measured in the first survey. Data of 710 children (377 boys and 333 girls) aged 8-13 years who completed the study were analyzed. No significant difference was observed in 24-h urine volumes between the two samples (median [interquartile range): 855.0 [600.0-1272.0) mL vs. 900.0 [660.0-1220.0) mL, P = 0.277). The mean 24-h urine creatinine excretion was regarded as representative of absolute daily creatinine excretion in children. Sex-specific, body-weight-adjusted creatinine excretion reference values were 15.3 mg/kg/day (0.1353 mmol/kg/day) for boys and 14.3 mg/kg/day (0.1264 mmol/kg/day) for girls. Differences were significant between boys and girls within the same age group but not across different age groups within the same sex. Ideal 24-h creatinine excretion values for height were derived for potential determination of the creatinine height index. These data can serve as reference ranges to calculate ratios of analyte to creatinine. The creatinine height index can be used to assess somatic protein status.

Associations between iodine intake, thyroid volume, and goiter rate in school-aged Chinese children from areas with high iodine drinking water concentrations.

BACKGROUND: Excessive iodine intake may have adverse effects on the thyroid, particularly in children, but the safe upper iodine intake concentration in children is unclear. OBJECTIVE: We assessed the adverse effects of high iodine intake from iodine-rich drinking water on thyroid size in children by examining associations between thyroid volume (Tvol), total goiter rate (TGR), and iodine intake. DESIGN: In a multistage cross-sectional survey, we collected two 24-h urine samples on 2 nonconsecutive days and determined 24-h urinary iodine excretion, then calculated habitual daily iodine intake. Ultrasonographic Tvol was measured, and TGR was calculated based on international and Chinese reference ranges for Tvol in children. RESULTS: This study included 2089 children from Shandong province, where the median (IQR) drinking water iodine concentration was 183 µg/L (69-406 µg/L). The median (IQR) 24-h urinary iodine concentrations for the 2 collections were 381 µg/L (203-649 µg/L) and 398 µg/L (202-687 µg/L), respectively. The median (IQR) habitual daily iodine intake of children was 298 µg/d (186-437 µg/d). Tvols were slightly higher in boys than in girls (P = 0.035). The overall TGR was 9.7% and did not differ by sex. The TGR was ∼5% for children aged 7-10 and 11-14 y at iodine intakes of 200-249 and 250-299 µg/d, respectively. With the use of logistic regression and 2-step linear regression, a nonlinear association was observed between Tvol, TGR, and iodine intake, with a threshold intake of 150 µg/d. CONCLUSIONS: Tvol begins to increase in children when iodine intake is ≥150 µg/d, and the TGR exceeds 5% when daily iodine intake is ≥250 µg/d for children aged 7-10 y and ≥300 µg/d for children aged 11-14 y. Our findings suggest that 150-249 and 150-299 µg/d seem to be safe upper iodine intake ranges for children aged 7-10 and 11-14 y, respectively. This trial was registered at clinicaltrials.gov as NCT02915536.

Urinary iodine excretion (UIE) estimated by iodine/creatinine ratio from spot urine in Chinese school-age children.

OBJECTIVE: To assess the validity of urinary iodine excretion (UIE) estimated by urinary iodine/creatinine ratio (UI/Cr) from spot urines in Chinese school-age children. DESIGN: A cross-sectional survey was performed in which twice-repeated collections of 24-h urine, and spot urine samples were obtained within 1 month. MEASUREMENTS: Urinary iodine concentration (UIC), urinary creatinine concentration (UCr), urine volume (Uvol) of spot and 24-h urine samples were measured. Measured 24-h UIE was calculated from 24-h UIC multiplied by 24-h Uvol, while the estimated 24-h UIE was calculated from spot UI/Cr multiplied by 24-h urinary creatinine excretion (24-h UCrE). RESULTS: No significant difference was observed in 24-h Uvol between two repeated collections (P = 0·70), while spot UIC, 24-h UIC, spot UI/Cr and measured 24-h UIE were significantly different (P < 0·05). The estimated 24-h UIE was 247 (136-431) µg/day in the first collection, lower than the measured 24-h UIE of 329 (183-536) µg/day (P < 0·001), while no significant difference was observed (P = 0·30) in the second sampling as the estimated 24-h UIE was 355 (168-624) µg/day and the measured 24-h UIE 350 (181-615) µg/day. The spot UIC (r = 0·57, P < 0·001), spot UI/Cr (r = 0·63, P < 0·001) and the estimated 24-h UIE (r = 0·83, P < 0·001) were strongly correlated with the measured 24-h UIE in the first collection. Likewise, in the second sampling, spot UIC (r = 0·60, P < 0·001), spot UI/Cr (r = 0·72, P < 0·001) and the estimated 24-h UIE (r = 0·89, P < 0·001) were also correlated with measured 24-h UIE. The Bland-Altman results indicated 95% of subjects were expected to locate within the limits of agreement (LOA), but showed an underestimation of the urinary iodine excretion by the estimated 24-h UIE. In addition, moderate-to-good agreement was found for the estimated and measured 24-h UIE, with kappa values of 0·55 and 0·66. CONCLUSIONS: Estimated 24-h UIE by UI/Cr ratio from spot urine could represent a valid and reliable alternative for measured 24-h UIE in estimating iodine excretion in children.

24-Hour Urine Samples Are More Reproducible Than Spot Urine Samples for Evaluation of Iodine Status in School-Age Children.

BACKGROUND: Variation in different urinary measurements for evaluation of iodine status is of concern to clinicians and researchers. OBJECTIVE: This study evaluated variations between urine iodine concentration (UIC), spot and 24-h urine sample creatinine concentrations, and 24-h urine iodine excretion (24-h UIE) in repeated samples from school-age children. METHODS: Urine samples (24 h and morning spot) were collected on 2 occasions from 981 children in Ningjin and Lingxian counties, China. Samples from Ningjin were collected in October and November 2013, and samples from Lingxian were collected in April and May 2014. Morning spot urine iodine concentration (MUIC), morning spot urine creatinine, 24-h UIC, and 24-h urine creatinine were measured in all samples. The 24-h UIE was calculated by multiplying the 24-h UIC by the 24-h urine volume. RESULTS: In Ningjin County, the 24-h UIC and 24-h UIE did not differ between repeated collections [192 and 172 µg/L, respectively, for 24-h UIC (P = 0.08); 123 and 120 µg/L, respectively, for 24-h UIE (P = 0.56)], whereas the MUIC was lower in November 2013 than in October 2013 (170 and 190 µg/L, respectively; P = 0.034). In Lingxian County, no significant differences were observed in 24-h UIC between the repeated collections (230 and 218 µg/L, respectively; P = 0.79), whereas the 24-h UIE and MUIC were higher in the samples collected in May 2014 than in April 2014 [161 and 155 µg/L, respectively, for 24-h UIE (P = 0.002); 244 and 203 µg/L, respectively, for MUIC (P < 0.001)]. When data from both counties were combined, no difference was observed between repeated 24-h UIC (214 compared with 196 µg/L; P = 0.17) and 24-h UIE (143 compared with 143 µg/d; P = 0.06), but MUICs were lower in the first collection than in the second collection (199 and 207 µg/L, respectively; P = 0.002). The κ values were >0.4 for 24-h UIC and mean UIE, whereas relatively low κ values were observed for MUIC and mean UIE. CONCLUSION: The 24-h UIC was more accurate and reproducible than the MUIC in evaluating iodine status in a large-scale population study of school-age children.

Selenium Level and Dyslipidemia in Rural Elderly Chinese.

OBJECTIVE: Higher selenium level has been hypothesized to have the potential to reduce the risk of cardiovascular diseases including dyslipidemia. However, results from previous studies are inconsistent. This study aims to determine the association between selenium level and dyslipidemia in elderly Chinese with relatively low selenium status. METHODS: A cross-sectional study of 1859 participants aged 65 or older from four rural counties in China was conducted. Serum total cholesterol (TC), triglycerides (TG), high density lipoprotein-cholesterol (HDLC) and low-density lipoprotein-cholesterol (LDLC), nail selenium concentration and APOE genotype were measured in all subjects. The four types of dyslipidemia were defined as >5.17 mmol/L for High-TC, >1.69 mmol/L for High-TG, >3.36 mmol/L for High-LDLC, and <1.04 mmol/L for Low-HDLC according to Chinese Guidelines on Prevention and Treatment of Dyslipidemia in Adults. Logistic models adjusting for age, gender, APOE genotype, body mass index, alcohol consumption, smoking, physical activity, medication use for cardiovascular diseases were used to examine the relationship between selenium levels and the risk of dyslipidemia. RESULTS: Mean nail selenium concentration was 0.465 µg/gin this sample. Rates for High-TC, High-LDLC, High-TG, Low-HDLC were 18.13%, 13.23%, 12.21% and 32.76% respectively. Results from logistic models indicated that higher selenium levels were significantly associated with higher risk of High-TC, High-LDLC and lower risk of Low-HDLC adjusting for covariates (p < 0.0001). Compared with the lowest selenium quartile group, participants in selenium quartile groups 2, 3 and 4 had significantly higher rates of High-TC, High-LDLC, High-TG, and lower rate of Low-HDLC adjusting for covariates. No significant association was observed between selenium level and the risk of High-TG. APOEε4 carriers had higher rates of High-TC and High-LDLC. There was no interaction between selenium level and APOE with the rates of dyslipidemia. CONCLUSIONS: Our results suggest long-term selenium exposure level may be associated with the risk of dyslipidemia in elderly population. Future studies are needed to examine the underlying mechanism of the association.

Effect of Excessive Potassium Iodide on Rat Aorta Endothelial Cells.

The aim of the current study was to investigate the effect of excess iodine on rat aorta endothelial cells and the potential underlying mechanisms. Rat aorta endothelial cells were cultured with iodide ion (3506, 4076, 4647, 5218, 5789, 6360, 6931, and 7512 mg/L) for 48 h. Morphological changes of cells were observed with microscope after Wright-Giemsa staining and acridine orange staining. Cell proliferation was determined with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and cell apoptosis was assessed with flow cytometry. The activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), endothelial nitric oxide synthase (eNOS), induced nitric oxide synthase (iNOS), and concentrations of malondialdehyde (MDA), glutathione (GSH), and protein carbonyl in culture medium were determined with colorimetric method. The expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was detected by enzyme linked immunosorbent assay. The results showed that excess iodine induced abnormal morphologic changes of cells, inhibited cell proliferation, and increased apoptosis rate. Iodine also reduced the activity of SOD, GSH-Px, and concentrations of GSH and increased the concentrations of MDA and protein carbonyl in a dose-dependent manner. Moreover, excess iodine decreased the activity of eNOS and increased the activity of iNOS and the expression of ICAM-1 and VCAM-1 in culture medium. Our results suggested that excess iodine exposure increased oxidative stress, caused damage of vascular endothelial cells, and altered the expression of adhesion factors and the activity of NOS. These changes may explain the mechanisms underlying excess iodine-induced vascular injury.

The association between selenium and lipid levels: a longitudinal study in rural elderly Chinese.

OBJECTIVE: A protective effect of selenium on lipid levels has been reported in populations with relatively low selenium status. However, recent studies found that high selenium exposure may lead to adverse cardiometabolic effects, particularly in selenium-replete populations. We examined the associations of selenium status with changes in lipid levels in a 7-year follow up of an elderly Chinese cohort including participants from selenium-deplete areas. METHODS: Study population consisted of 140 elderly Chinese aged 65 or older with nail selenium levels measured at baseline (2003-2005). Lipid concentrations were measured in fasting blood samples collected at baseline and the 7-year follow-up (2010-2012). Analysis of covariance (ANCOVA) models was used to determine the association between baseline selenium status and changes in lipid levels from baseline to follow-up adjusting for other covariates. RESULTS: Mean (±standard deviation) baseline selenium concentration was 0.41±0.2mg/kg. In prospective analysis, we found that individuals in the highest selenium quartile group showed 1.11 SD decrease on total-cholesterol (p<0.001), 0.41 SD increase on HDL-cholesterol (p<0.001) and 0.52 SD decrease on triglyceride after 7 years than those in the lowest selenium quartile group. The similar trends were seen with significant lipid changes in the 2nd and 3rd quartile groups. CONCLUSION: Selenium has modest beneficial effects on blood lipid levels in a population with relatively low selenium status. Our result suggests adequate dietary selenium intake as a potential prevention strategy for lowering lipid levels in selenium deplete populations.

The relationship between cholesterol and cognitive function is homocysteine-dependent.

INTRODUCTION: Previous studies have identified hyperlipidemia as a potential risk factor for dementia and Alzheimer's disease. However, studies on cholesterol measured in late-life and cognitive function have been inconsistent. Few studies have explored nonlinear relationships or considered interactions with other biomarker measures. METHODS: A cross-sectional sample of 1,889 participants from four rural counties in the People's Republic of China was included in this analysis. Serum total cholesterol, high-density lipoprotein, triglycerides, and homocysteine levels were measured in fasting blood samples. A composite cognitive score was derived based on nine standardized cognitive test scores. Analysis of covariance models were used to investigate the association between biomarker measures and the composite cognitive scores. RESULTS: There was a significant interaction between the homocysteine quartile group and the cholesterol quartile group on cognitive scores (P=0.0478). In participants with normal homocysteine levels, an inverse U-shaped relationship between total cholesterol level and cognitive score was found, indicating that both low and high cholesterol levels were associated with lower cognitive scores. In participants with high homocysteine levels, no significant association between cholesterol and cognition was found. CONCLUSION: The relationship between cholesterol levels and cognitive function depends upon homocysteine levels, suggesting an interactive role between cholesterol and homocysteine on cognitive function in the elderly population. Additional research is required to confirm our findings in other populations, and to explore potential mechanisms underlying the lipid-homocysteine interaction.

Geographical distribution patterns of iodine in drinking-water and its associations with geological factors in Shandong Province, China.

County-based spatial distribution characteristics and the related geological factors for iodine in drinking-water were studied in Shandong Province (China). Spatial autocorrelation analysis and spatial scan statistic were applied to analyze the spatial characteristics. Generalized linear models (GLMs) and geographically weighted regression (GWR) studies were conducted to explore the relationship between water iodine level and its related geological factors. The spatial distribution of iodine in drinking-water was significantly heterogeneous in Shandong Province (Moran's I = 0.52, Z = 7.4, p < 0.001). Two clusters for high iodine in drinking-water were identified in the south-western and north-western parts of Shandong Province by the purely spatial scan statistic approach. Both GLMs and GWR indicated a significantly global association between iodine in drinking-water and geological factors. Furthermore, GWR showed obviously spatial variability across the study region. Soil type and distance to Yellow River were statistically significant at most areas of Shandong Province, confirming the hypothesis that the Yellow River causes iodine deposits in Shandong Province. Our results suggested that the more effective regional monitoring plan and water improvement strategies should be strengthened targeting at the cluster areas based on the characteristics of geological factors and the spatial variability of local relationships between iodine in drinking-water and geological factors.

Cognitive function, body mass index and mortality in a rural elderly Chinese cohort.

BACKGROUND: Previous studies have shown that poor cognition and low body mass index were associated with increased mortality. But few studies have investigated the association between cognition and mortality across the entire cognitive spectrum while adjusting for BMI. The objective of this study is to examine the associations between cognitive function, BMI and 7-year mortality in a rural elderly Chinese cohort. METHODS: A prospective cohort of 2,000 Chinese age 65 and over from four rural counties in China were followed for 7-years. Cognitive function, BMI and other covariate information were obtained at baseline. Cox's proportional hazard models were used to determine the effects of cognitive function and BMI on mortality risk. RESULTS: Of participants enrolled, 473 (23.7%) died during follow-up. Both lower cognitive function (HR = 1.48, p = 0.0049) and lower BMI (HR = 1.6, p < 0.0001) were independently associated with increased mortality risk compared to individuals with average cognitive function and normal weight. Higher cognitive function was associated with lower mortality risk (HR = 0.69, p = 0.0312). We found no significant difference in mortality risk between overweight/obese participants and those with normal weight. CONCLUSIONS: Cognitive function and BMI were independent predictors of mortality risk. Intervention strategies for increasing cognitive function and maintaining adequate BMI may be important in reducing morality risk in the elderly population.

Effect of combined excess iodine and low-protein diet on thyroid hormones and ultrastructure in Wistar rats.

The aim of the present study was to illustrate the combined effect of excess iodine and low-protein diet on the thyroid, and the potential molecular mechanism of this effect. One hundred ninety-two Wistar rats were randomly divided into the following groups: normal; 10- (10HI), 50- (50HI), or 100-fold excess iodine (100HI); low-protein; and low-protein combined with 10- (L10HI), 50- (L50HI), or 100-fold excess iodine (L100HI). At the end of 2, 4, or 6 months, the rats were sacrificed for iodine concentration and thyroid hormone analyses. The histological appearance of the thyroid gland was observed at the end of 6 months. At the end of 6 months, the serum total thyroxine (TT4), free thyroxine (FT4), total triiodothyronine (TT3), and free triiodothyronine (FT3) levels in the 100HI, L10HI, L50HI, and L100HI groups were significantly lower than the control group (P < 0.05 or P < 0.01). Serum TT4, FT4, TT3, and FT3 levels in the low-protein excess iodine groups were significantly lower than the groups with an equal amount of excess iodine alone (P < 0.05 or P < 0.01). Light and electron microscopy showed that excess iodine caused damage to the ultrastructure of thyroid and apoptosis of follicular epithelial cells. In the 100HI, L50HI, and L100HI groups, thyroid follicular epithelial cells became flattened, and follicles became distended with colloid. The damage was more serious in low-protein groups. The present findings demonstrated that the low-protein diet aggravated the damage to the thyroid caused by excess iodine alone.

[Spatial distribution characteristics of iodine in drinking water in Shandong province between year 2008 and 2010].

OBJECTIVE: To detect the spatial distribution characteristics of iodine in drinking water of residents in Shandong province with spatial autocorrelation analysis. METHODS: The county-based study set Shandong province as a research site. A total of 108 164 water samples from 140 counties were collected. The drinking water iodine data in county-level city between 2008 to 2010 were obtained from Shandong Institute of Prevention and Control for Endemic Disease and was merged with an electronic map to build a spatial database. Global and local Moran's I index were calculated, respectively, and spatial autocorrelation and cluster range of iodine distribution in drinking water in Shandong province were studied by SaTScan software. RESULTS: All counties were further grouped according to the "criteria of delimitation for IDD endemic areas" and "determination and classification of the areas of high water iodine and the endemic areas of iodine excess goiter", and 90 counties were iodine deficiency (< 10 µg/L), 31 were iodine suitable (10 - 150 µg/L), and 19 (> 150 µg/L) were high iodine. For the overall study area, the iodine distribution in drinking water in Shandong province existed spatial autocorrelation (Moran's I = 0.52, Z = 7.4, P < 0.01). For the local scale, the drinking water iodine in 18 counties of Dezhou, Liaocheng and Heze city in western Shandong province was clustered, the local Moran's I were between 0.22 - 1.00 (P < 0.01), which were all high-high clusters, indicating the positive spatial correlation. Spatial analysis using SaTScan software detected two cluster areas including 20 counties, which the centers located in Xiajin and Dingtao county, the cluster radiuses were 57.47 km and 65.58 km respectively. The analysis results were consistent with the results of local spatial autocorrelation. CONCLUSION: There are apparent spatial autocorrelation and strong spatial heterogeneity existed in the iodine distribution in drink water in Shandong province.

Late life leisure activities and risk of cognitive decline.

BACKGROUND: Studies concerning the effect of different types of leisure activities on various cognitive domains are limited. This study tests the hypothesis that mental, physical, and social activities have a domain-specific protection against cognitive decline. METHODS: A cohort of a geographically defined population in China was examined in 2003-2005 and followed for an average of 2.4 years. Leisure activities were assessed in 1,463 adults aged 65 years and older without cognitive or physical impairment at baseline, and their cognitive performances were tested at baseline and follow-up examinations. RESULTS: High level of mental activity was related to less decline in global cognition (ß = -.23, p < .01), language (ß = -.11, p < .05), and executive function (ß = -.13, p < .05) in ANCOVA models adjusting for age, gender, education, history of stroke, body mass index, Apolipoprotein E genotype, and baseline cognition. High level of physical activity was related to less decline in episodic memory (ß = -.08, p < .05) and language (ß = -.15, p < .01). High level of social activity was associated with less decline in global cognition (ß = -.11, p < .05). Further, a dose-response pattern was observed: although participants who did not engage in any of the three activities experienced a significant global cognitive decline, those who engaged in any one of the activities maintained their cognition, and those who engaged in two or three activities improved their cognition. The same pattern was observed in men and in women. CONCLUSIONS: Leisure activities in old age may protect against cognitive decline for both women and men, and different types of activities seem to benefit different cognitive domains.

Selenium level and depressive symptoms in a rural elderly Chinese cohort.

BACKGROUND: Selenium is considered a protective agent against free radicals through the maintenance of better enzyme activity. The few studies examining the relationship between selenium and depression have yielded inconsistent results and none of these studies considered the role of cognitive function in this context. METHODS: A cross-sectional evaluation of 1737 rural Chinese age 65 and over from two provinces in China was conducted. Depressive symptoms were assessed using the Geriatric Depression Scale (GDS). Cognitive function was assessed using various cognitive instruments. Selenium measures were obtained from nail samples. Other information collected included demographic characteristics and medical history. Analysis of covariance models were used to identify factors associated with GDS score. RESULTS: Higher selenium levels were associated with lower GDS scores adjusting for demographic and medical conditions (p=0.0321). However, the association between selenium and depressive symptoms was no longer significant when cognitive function score was adjusted in the model (p=0.2143). CONCLUSIONS: Higher selenium level was associated with lower depressive symptoms without adjusting for cognition in this cohort. However, after cognition was adjusted in the model the association between selenium and depressive symptoms was no longer significant, suggesting that selenium's association with depressive symptoms may be primarily through its association with cognitive function.

Normative data for neuropsychological tests in a rural elderly Chinese cohort.

Normative information is important for appropriate interpretation of cognitive test scores as a critical component of dementia diagnosis in the elderly population. A cross-sectional evaluation of 1826 participants aged 65 years and older from four rural counties in China was conducted using six cognitive instruments including tests of global cognitive function (the Community Screening Instrument for Dementia), memory (Word List Learning and Recall tasks from the Consortium to Establish a Registry for Alzheimer's Disease, IU Story), language (Animal Fluency Test), and executive function (IU Token). Multiple regression models adjusting for demographic variables were used to provide standardized residuals z-scores and corresponding percentile ranking for each cognitive test. In all cognitive tests older age was associated with worse test performance while exposure to education was related to better cognitive test performance. We also detected a significant gender difference with men scoring better than women and a significant gender by education interaction on two tests. The interaction indicates that gender difference in test scores was much smaller in participants with more education than those who had less or no education. These demographically adjusted, regression-based norms can be a useful tool to clinicians involved with differential diagnosis of cognitive and memory disorders in older adults in rural China.

[Epidemiological investigation on endemic fluorosis along the Yellow River alluvial plain of Shandong province].

OBJECTIVE: To investigate the current prevalent status of endemic fluorosis in the floodplain area of the lower Yellow River in Shandong province. METHODS: According to "The National Technical Scheme for Endemic Disease Control in 2008", 16 counties were chosen to carry out the epidemiological survey of endemic fluorosis. Three villages were chosen in each county, to determine the fluoride content of drinking water and to check the dental fluorosis of children aged 8 to 12 year old, the skeletal fluorosis of adults over 16 years of age. Both children and adults were tested for urine fluoride. The content of fluoride in drinking water and urine was determined by F-ion selective electrode while dental fluorosis of children aged 8 to 12 years old was diagnosed by Dean's method and adults skeletal fluorosis by the National Standard for "Diagnosis of endemic skeletal fluorosis" (WS 192-2008). RESULTS: The investigation was taken place in 26 'improved-water-quality' villages in 16 counties, among which 19 villages had water fluoride content ≤ 1.00 mg/L and accounted for 73.08% (19/26), 7 villages had water fluoride content > 1.00 mg/L and accounted for 26.92% (7/26), with the highest water fluoride content as 3.73 mg/L. In 22 'yet to improve-water quality' villages in 16 counties, 5 villages had water fluoride content ≤ 1.00 mg/L (accounted for 22.73%), 17 villages had water fluoride content > 1.00 mg/L (accounted for 77.27%), with the highest water fluoride content as 3.38 mg/L. The overall rate of dental fluorosis among children aged 8 to 12 years old was 52.18% (1042/1997), with the index of dental fluorosis as 1.17 and the rate of dental damage as 8.01% (160/1997). The urinary fluoride values above 1.40 mg/L were found in 65.00% (845/1300) of children aged 8 to 12 years old, with the highest urinary fluoride concentrations as 18.53 mg/L. The rate of skeletal fluorosis by clinic and X-rays in adults older than 16 years old were 4.35% (1121/25 781) and 11.36% (5/44), respectively. The urinary fluoride values above 1.60 mg/L were found as 63.92% (606/948) in adults older than 16 years old, with the highest urinary fluoride concentrations as 21.35 mg/L. CONCLUSION: The status of endemic fluorosis had not been effectively controlled and the situation for endemic fluorosis control was still critical in the floodplain area of the lower Yellow River in Shandong province, suggesting that the preventive approaches on endemic fluorosis control should be strengthened.

[Study on selenium exposure level related to cognitive function in rural elderly people].

OBJECTIVE: To know the relationship between selenium exposure level and cognitive function and its influencing factors in rural elderly people. METHODS: A cross-sectional survey of 200 local rural elderly people were conducted by using dietary questionnaire and six cognitive questionnaires. The local environment samples were collected including food and nail and blood sample of study individuals. The trace amount of selenium were determined with 2, 3-diaminonaphthalenet fluorometric determination. Multiple stepwise regression was used to examine the association between selenium exposure level and the composite Z score adjusting for age, gender, education, and other factors that might influence the cognitive scores. RESULTS: There were significant positively relationships between three selenium exposure indexes. The results showed that food selenium intake level and blood selenium level could significantly affected the Z score after adjusting age, education and other factors by using multiple stepwise regression analysis (P < 0.001). CONCLUSION: Lower selenium exposure level maybe associated with lower cognitive function in rural elderly people.

[Study on genetic polymorphism of human mismatch repair gene hMLH1 and susceptibility of papillary thyroid carcinoma in Chinese Han people].

OBJECTIVE: To explore the associations between the single nucleotide polymorphism of human mismatch repair gene hMLH1 and the papillary thyroid carcinoma (PTC) in Chinese Han people. METHODS: A hospital based 1:1 matched case-control study was carried out. The single nucleotide polymorphism (-93G > A, 1151T > A and 655A > G) for 204 pairs of cases with PTC as well as healthy controls was identified by PCR-RFLP, PCR-ASO and DNA sequencing. RESULTS: With univariate analysis, we found that compared to 1151TT genotype, the TA genotype could increase the PTC risk marginally, with odds ratio (OR) of 2.15 (95%CI: 0.99 - 4.85); While the mutant genotype TA + AA could increase the PTC risk statistically significant, with OR of 2.15(95%CI: 1.02 - 4.69). With 2 x 4 cross-over study, we found that compared to -93GG and 1151TT genotypes, individuals with both -93GA + AA and 1151TA + AA could increase the PTC risk marginally, with OR of 2.50 (95%CI: 0.96 - 6.67); While, compared to 655AA and 1151TT genotypes, individuals with both 655AA and 1151TA + AA could increase the PTC risk statistically significant, with OR of 2.50 (95%CI: 1.02 - 4.73). Multivariate and conditional logistic regression analysis showed the genotype of 1151TA, the history of receiving CT diagnosis, the history of tumor, the negative life events and eating seafood frequently could increase the risk of PTC, with OR of 6.79 (95%CI: 3.18 - 14.49), 3.35 (95%CI: 1.93 - 5.80), 39.03 (95%CI: 3.70 - 41.60) and 3.98 (95%CI: 1.81 - 8.73); While, eating fruit frequently could decrease the PTC risk. CONCLUSION: The 1151TA + AA genotype, the history of receiving CT diagnosis, the history of tumor, the negative life events and eating seafood frequently were the risk factors of PTC, while eating fruit frequently was the protective factor.