Dianjun Sun

Geographical distribution of drinking-water with high iodine level and association between high iodine level in drinking-water and goitre: a Chinese national investigation

Excessive iodine intake can cause thyroid function disorders as can be caused by iodine deficiency. There are many people residing in areas with high iodine levels in drinking-water in China. The main aim of the present study was to map the geographical distribution of drinking-water with high iodine level in China and to determine the relationship between high iodine level in drinking-water and goitre prevalence. Iodine in drinking-water was measured in 1978 towns of eleven provinces in China, with a total of 28,857 water samples. We randomly selected children of 8-10 years old, examined the presence of goitre and measured their urinary iodine in 299 towns of nine provinces. Of the 1978 towns studied, 488 had iodine levels between 150 and 300 μg/l in drinking-water, and in 246 towns, the iodine level was >300 μg/l. These towns are mainly distributed along the original Yellow River flood areas, the second largest river in China. Of the 56 751 children examined, goitre prevalence was 6.3 % in the areas with drinking-water iodine levels of 150-300 μg/l and 11.0 % in the areas with drinking-water iodine >300 μg/l. Goitre prevalence increased with water and urinary iodine levels. For children with urinary iodine >1500 μg/l, goitre prevalence was 3.69 times higher than that for those with urinary iodine levels of 100-199 μg/l. The present study suggests that drinking-water with high iodine levels is distributed in eleven provinces of China. Goitre becomes more prevalent with the increase in iodine level in drinking-water. Therefore, it becomes important to prevent goitre through stopping the provision of iodised salt and providing normal drinking-water iodine through pipelines in these areas in China.

Iodine Deficiency and Excess Coexist in China and Induce Thyroid Dysfunction and Disease: A Cross-Sectional Study

Background In spite of the salt iodization, iodine deficiency disorders (IDD) have not been sustainably eliminated in China. There are coastal areas with low iodized salt coverage rates (iodine nutrition is inadequate) and other areas with excessive amounts of iodine in the drinking water. Objective This study aimed to clarify the association of iodine deficiencies resulting from a low coverage rate of iodized salt, excess iodine intake from drinking water with thyroid function and disease in adults. Design A cross-sectional study was conducted in adults in different iodine nutrition areas in three provinces in China. Results The prevalence of thyroid nodules was 15.52%, 8.66% and 22.17% in the iodine excess, sufficient and deficient groups, respectively. The prevalence of subclinical hypothyroidism was 20.09%, 10.41%, and 2.25% in the excess, sufficient and deficient iodine groups, respectively. The prevalence of subclinical hyperthyroidism and overt hyperthyroidism in the iodine deficient group was higher than that in the iodine excess group (u200a=u200a9.302, pu200a=u200a0.002) and iodine sufficient group (u200a=u200a7.553, pu200a=u200a0.006). Thyroid-stimulating hormone (TSH) was significantly correlated with excess iodine intake (βu200a=u200a1.764,Pu200a=u200a0.001) and deficient iodine intake (βu200a=u200a−1.219, Pu200a=u200a0.028). Conclusions Thyroid nodules are more likely to be present in the iodine excess and deficient areas than in the iodine sufficient areas. Subclinical hyperthyroidism and overt hyperthyroidism are more likely to be prevalent in the iodine deficient areas than in the iodine excess or sufficient areas. Subclinical hypothyroidism is more likely to be prevalent in the high iodine intake areas than in the iodine deficient or sufficient areas. Median TSH may be deemed as an alternative indicator for monitoring the iodine nutrition status of the adult population in iodine excess and deficient areas.

A national cross-sectional study on effects of fluoride-safe water supply on the prevalence of fluorosis in China.

Objective To assess the effects of provided fluoride-safe drinking-water for the prevention and control of endemic fluorosis in China. Design A national cross-sectional study in China. Setting In 1985, randomly selected villages in 27 provinces (or cities and municipalities) in 5 geographic areas all over China. Participants Involved 81u2005786 children aged from 8 to 12 and 594u2005698 adults aged over 16. Main outcome measure The prevalence of dental fluorosis and clinical skeletal fluorosis, the fluoride concentrations in the drinking-water in study villages and in the urine of subjects. Results The study showed that in the villages where the drinking-water fluoride concentrations were higher than the government standard of 1.2u2005mg/l, but no fluoride-safe drinking-water supply scheme was provided (FNB areas), the prevalence rate and index of dental fluorosis in children, and prevalence rate of clinical skeletal fluorosis in adults were all significantly higher than those in the historical endemic fluorosis villages after the fluoride-safe drinking-water were provided (FSB areas). Additionally, the prevalence rate of dental fluorosis as well as clinical skeletal fluorosis, and the concentration of fluoride in urine were found increased with the increase of fluoride concentration in drinking-water, with significant positive correlations in the FNB areas. While, the prevalence rate of dental fluorosis and clinical skeletal fluorosis in different age groups and their degrees of prevalence were significantly lower in the FSB areas than those in the FNB areas. Conclusions The provision of fluoride-safe drinking-water supply schemes had significant effects on the prevention and control of dental fluorosis and skeletal fluorosis. The study also indicated that the dental and skeletal fluorosis is still prevailing in the high-fluoride drinking-water areas in China.

Eliminating Iodine Deficiency in China: Achievements, Challenges and Global Implications

The prevention of iodine deficiency through salt iodization has been recognized as a global success story, and China stands at the forefront of this achievement with one of the most successful programs in the world. High level political commitment, national mandatory legislation, a state-managed edible salt industry and a complex and highly sophisticated surveillance system have facilitated the success of the program. Challenges have arisen however, including: (i) concern that adequate iodine status in pregnant women cannot be achieved without causing above adequate iodine intakes in children; (ii) declining iodine intake as a result of reductions in salt consumption and increased consumption of processed foods, which may not be made with iodized salt; (iii) the existence of areas with high iodine content in the water; and (iv) declines in household use of iodized salt due to concerns about excess iodine intake and thyroid disease. This article reviews the achievements and challenges of the Chinese Iodine Deficiency Disorders (IDD) Elimination Program and reflects on lessons learned and implications for other national salt iodization programs.

Intra-individual variation in urinary iodine concentration: effect of statistical correction on population distribution using seasonal three-consecutive-day spot urine in children

Objective To determine the effect of statistical correction for intra-individual variation on estimated urinary iodine concentration (UIC) by sampling on 3 consecutive days in four seasons in children. Setting School-aged children from urban and rural primary schools in Harbin, Heilongjiang, China. Participants 748 and 640 children aged 8–11u2005years were recruited from urban and rural schools, respectively, in Harbin. Primary and secondary outcome measures The spot urine samples were collected once a day for 3 consecutive days in each season over 1u2005year. The UIC of the first day was corrected by two statistical correction methods: the average correction method (average of days 1, 2; average of days 1, 2 and 3) and the variance correction method (UIC of day 1 corrected by two replicates and by three replicates). The variance correction method determined the SD between subjects (Sb) and within subjects (Sw), and calculated the correction coefficient (Fi), Fi=Sb/(Sb+Sw/di), where di was the number of observations. The UIC of day 1 was then corrected using the following equation: Results The variance correction methods showed the overall Fi was 0.742 for 2u2005days’ correction and 0.829 for 3u2005days’ correction; the values for the seasons spring, summer, autumn and winter were 0.730, 0.684, 0.706 and 0.703 for 2u2005days’ correction and 0.809, 0.742, 0.796 and 0.804 for 3u2005days’ correction, respectively. After removal of the individual effect, the correlation coefficient between consecutive days was 0.224, and between non-consecutive days 0.050. Conclusions The variance correction method is effective for correcting intra-individual variation in estimated UIC following sampling on 3 consecutive days in four seasons in children. The method varies little between ages, sexes and urban or rural setting, but does vary between seasons.

Prolactin rs1341239 T allele may have protective role against the brick tea type skeletal fluorosis.

Objective Prolactin (PRL) has been reported to be associated with increased bone turnover, and increased bone turnover is also a feature of skeletal fluorosis (SF). Autocrine/paracrine production of PRL is regulated by the extrapituitary promoter and a polymorphism in the extrapituitary PRL promoter at -1149 (rs1341239) is associated with disturbances of bone metabolism in other diseases. Here, we have investigated the possibility that the rs1341239 polymorphism is associated with SF, which results from the consumption of brick tea. Design We conducted a cross-sectional study in Sinkiang, Qinghai, Inner Mongolia in China. Demography survey questionnaires were completed and physical examination and X-ray diagnoses were used to diagnose SF. Brick tea water fluoride intake (IF) and urinary fluoride (UF) were tested by an F-ion selective electrode method. A Sequenom MassARRAY system was used to determine PRL gene polymorphisms. Results Subjects who were younger than 45 years of age and carried the T allele had a significantly decreased risk of SF [OR = 0.279 (95%CI, 0.094–0.824)] compared to those carrying the homozygous G allele. This phenomenon was only observed in Kazakh subjects [OR = 0.127 (95%CI, 0.025–0.646)]. Kazakh females who carried T alleles has a decreased risk of SF [OR = 0.410 (95%CI, 0.199–0.847)]. For Kazakh subjects which IF is less than 3.5 mg/d, a decreased risk of SF was observed among the participants who carried T alleles [OR = 0.118 (95%CI, 0.029–0.472)]. Overall, subjects with 1.6–3.2 mg/L UF and carried T alleles had a significantly decreased risk of SF [OR = 0.476 (95%CI, 0.237–0.955)] compared to homozygous G allele carriers. This phenomenon was only observed in Kazakh subjects [OR = 0.324 (95%CI, 0.114–0.923)]. Conclusions Our results suggested that the PRL rs1341239 T allele decreases the risk of brick tea SF.

Role of pigment epithelium-derived factor (PEDF) on arsenic-induced neuronal apoptosis

Chronic exposure to high levels of arsenic is closely associated with nervous system disorders that harm learning, memory, and intelligence. Studies have shown that the primary characteristic of brain damage is neuronal apoptosis. Arsenic induces apoptosis in a variety of nerve cells. Therefore, substance that inhibit apoptosis promise to mitigate arsenic toxicity. Pigment epithelium-derived factor (PEDF) is widely distributed in brain tissues and has various effects on neurons, including induction of apoptosis. Our previous study suggested that PEDF might augment arsenic-induced apoptosis in rat brains. In this study of 151 adults with normal, mild, moderate, and high exposure to arsenic, the measured serum PEDF levels were 15.46u202f±u202f5.87u202fng/mL, 17.33u202f±u202f8.22u202fng/mL, 19.43u202f±u202f9.51u202fng/mL and 21.65u202f±u202f14.46u202fng/mL, respectively. Multiple linear regression analysis revealed an independent positive correlation between serum PEDF levels and arsenic exposure in drinking water. To study the underlying mechanism of arsenic-induced apoptosis, we exposed PEDF-transfected PC12u202fcells to NaAsO2. We discovered that NaAsO2--induced mitochondrial apoptosis was enhanced in cells that over expressed PEDF. Moreover, p53 up regulated modulator of apoptosis (PUMA) gene and B-cell lymphoma 2 (Bcl-2) protein were primary factors in the progression of arsenic-induced apoptosis. Taken together, our results suggest that PEDF inhibition might mitigate arsenic toxicity to nerve cells.

Nitric oxide is involved in the hypothyroidism with significant morphology changes in female Wistar rats induced by chronic exposure to high water iodine from potassium iodate

Epidemiological studies indicated that chronic exposure to high water iodine is associated with primary hypothyroidism (PH) and subclinical hypothyroidism (SCH). However, the mechanism is not well understood. In this study, we explored whether chronic exposure to high water iodine from potassium iodate (KIO3) can induce hypothyroidism in addition to determining if nitric oxide (NO) is involved in the pathogenesis. 96 female Wistar rats were divided into six groups: control, I1000μg/L, I3000μg/L, I6000μg/L, N-nitro-L-arginine methylester (L-NAME) and L-NAME+I6000μg/L. After 3 months, urine iodine concentration, thyroid hormone, NO and nitric oxide synthase (NOS) serum levels were determined. Additionally, thyroid expression of inducible nitric oxide synthase (iNOS) was also investigated. Thyroid morphology was observed under light microscopy and transmission electron microscope. SCH as indicated by elevated serum thyrotropin (TSH) was induced among rats exposed to 3000u202fμg/L I-, while rats treated with 6000u202fμg/L I- presented PH characterized by elevated TSH and lowered total thyroxine in serum. Moreover, serum NO, NOS and iNOS expression in the thyroid were significantly increased in I3000μg/L and I6000μg/L groups. Changes in thyroid function and morphology in the L-NAME+I6000μg/L group were extenuated compared to I6000μg/L group. These findings suggested that chronic exposure to high water iodine from KIO3 likely induces hypothyroidism with significant morphology changes in female Wistar rats and NO appears to be involved in the pathogenesis.

Should urinary iodine concentrations of school-aged children continue to be used as proxy for different populations? Analysis of data from Chinese national surveys

I deficiency is a worldwide public health problem. Median urinary I concentration in school-aged children has been used globally as a proxy for all populations. This study aims to determine whether median urinary I concentration of school-aged children is an appropriate indicator of I nutritional status in different adult populations. This is a secondary data analysis of two national I Deficiency Disorder surveys (2011, 2014) and two regional surveys (in coastal areas, 2009, and in high-risk areas, 2009-2014). Population groups included in these surveys were school-aged children (8-10 years), pregnant women, lactating women, women of childbearing age and adults (men and women, 18-45 years). All participants were self-reported healthy without history of thyroid diseases or were not using thyroid medicines. The median urinary I concentration of school-aged children was matched with that of the other population at the county level. The matched populations had similar iodised salt supply, food and water I, food composition and I content in salt. Weak or moderate correlation of median urinary I concentrations was observed between school-aged children and pregnant women and between children and lactating women. However, the agreement was stronger between children and women of childbearing age and between children and adult men and women. The results could be affected by cut-off values, data aggregation level and sample size. Using median urinary I concentration of school-aged children tends to overestimate that of pregnant women and lactating women. Median urinary I concentration of school-aged children can be used for assessing I nutrition in the adult population.

CHAPTER 33:Dietary Calcium and Osteoprotegerin

Calcium is an essential trace element of human body. It is both the constructor and regulator of the body, and the source of our human life. Osteoprotegerin (OPG) is a glycoprotein involved in bone metabolism and plays a regulatory role in the immune, the skeletal and the circulatory systems. In recent years, the level of circulating OPG has become an independent biomarker of cardiovascular disease, not only for patients with acute or chronic heart disease, but also for healthy people. Furthermore, OPG has been involved in various inflammations and is closely associated with diabetes mellitus and poor glycaemic control. In view of the function of calcium and the role of OPG in calcification, the potential interaction between dietary calcium and OPG deserves much attention.