Association of arsenobetaine with beta-cell function assessed by homeostasis model assessment (HOMA) in nondiabetic Koreans: data from the fourth Korea National Health and Nutrition Examination Survey (KNHANES) 2008-2009

Research for type 2 diabetes mellitus in endemic arsenism areas in central China: role of low level of arsenic exposure and KEAP1 rs11545829 polymorphism

Type 2 diabetes mellitus (T2DM) is one of the major public health problems worldwide; both genetic and environmental factors are its risk factors. Arsenic, an environmental pollutant, might be a risk factor for T2DM, but the association of low-to-moderate level arsenic exposure with the risk of T2DM is still inconsistent. Single nucleotide polymorphisms (SNPs) can affect the development of T2DM, but the study on KEAP1 rs11545829 (G>A) SNP is few. In this paper, we explored the effect of KEAP1 rs11545829 (G>A) SNP and low-to-moderate level arsenic exposure on risk of T2DM in a cross-sectional case-control study conducted in Shanxi, China. Total of 938 participants, including 318 T2DM cases and 618 controls, were enrolled. Blood glycosylated haemoglobin (HbA1c) was detected by Automatic Biochemical Analyzer, and participants with HbA1c≧6.5% were diagnosed as T2DM. Urinary total arsenic (tAs, mg/L), as the indicator of arsenic exposure, was detected by liquid chromatography-atomic fluorescence spectrometry (LC-AFS). Genomic DNA was extracted and the genotypes of KEAP1 rs11545829 SNP were examined by multiplex polymerase chain reaction (PCR). The urinary tAs concentration in recruited participants was 0.075 (0.03-0.15) mg/L, and was associated with an increased risk of T2DM (OR = 8.45, 95% CI 2.63-27.17); rs11545829 mutation homozygote AA genotype had a protective effect on risk of T2DM (OR = 0.42, 95 % CI 0.25-0.73). Although this protective effect of AA genotype was found in participants with higher urinary tAs level (>0.032 mg/L) (OR = 0.48, 95% CI 0.26-0.86), there was no interaction effect for arsenic exposure and rs11545829 SNP on risk of T2DM. In addition, BMI modified the association between rs11545829 SNP and the risk of T2DM (RERI = -1.11, 95% CI -2.18-0.04). The present study suggest that low-to-moderate level arsenic exposure may be a risk factor, while KEAP1 rs11545829 SNP mutation homozygote AA genotype may be a protective factor for risk of T2DM, especially for T2DM patients with urinary tAs level>0.032 mg/L.

Arsenic exposure during pregnancy and postpartum maternal glucose tolerance: evidence from Bangladesh

BACKGROUND

Arsenic exposure has been associated with gestational diabetes mellitus. However, the extent to which arsenic exposure during pregnancy is associated with postpartum glucose intolerance is unknown.

METHODS

We studied 323 women in Bangladesh. We assessed arsenic exposure in early pregnancy via toenail and water samples. We measured fasting glucose and insulin in serum at a mean (SD) of 4.0 (3.5) weeks post-delivery. We ran covariate-adjusted, linear regression models to examine associations of arsenic concentrations with HOMA-IR, a marker of insulin resistance, and HOMA-β, a marker of beta cell function.

RESULTS

Median (IQR) arsenic concentration was 0.45 (0.67) μg/g in toenails and 2.0 (6.5) μg/L in drinking water. Arsenic concentrations during pregnancy were not associated with insulin resistance or beta cell function postpartum. HOMA-IR was 0.07% (- 3.13, 3.37) higher and HOMA-β was 0.96% (- 3.83, 1.99) lower per IQR increment in toenail arsenic, but effect estimates were small and confidence intervals crossed the null.

CONCLUSIONS

Although arsenic exposure during pregnancy has been consistently associated with gestational diabetes mellitus, we found no clear evidence for an adverse effect on postpartum insulin resistance or beta cell function.

Joint effect of urinary arsenic species and serum one-carbon metabolism nutrients on gestational diabetes mellitus: A cross-sectional study of Chinese pregnant women

BACKGROUND

Growing evidence indicates that arsenic (As) exposure can increase the risk of gestational diabetes mellitus (GDM). However, little is known about As species and GDM and the combined effect of As and one-carbon metabolism (OCM) on GDM.

OBJECTIVES

We aimed to examine the associations between As species and GDM and evaluate the potential interactions of folate, vitamin B₁₂, and homocysteine (Hcy) with As species on GDM prevalence.

METHOD

We measured levels of arsenite (As³⁺), arsenate (As⁵⁺), dimethylarsinic acid (DMA), and arsenobetaine (AsB) species in urine and folate, vitamin B₁₂, and Hcy in serum from 396 pregnant women in Tianjin, China. The diagnosis of GDM was based on an oral glucose tolerance test. Associations of As species in urine with GDM were evaluated using generalized linear models (GLMs) and Bayesian kernel machine regression (BKMR). Additive interactions of As and OCM with GDM were estimated by determining the relative excess risk due to interaction (RERI).

RESULTS

Of the 396 pregnant women, 89 were diagnosed with GDM. Continuous increases in urinary inorganic As were associated with GDM in the GLMs, with adjusted odds ratios of 2.12 (95% CI: 0.96, 4.71) for As³⁺, and 0.27 (95% CI: 0.07, 0.98) for As⁵⁺. The BKMR in estimating the exposure-response functions showed that As³⁺ and AsB were positively associated with GDM. However, As⁵⁺ showed a negative relationship with GDM. Although the additive interactions between As exposure and OCM indicators were not significant, we found that pregnant women with higher urinary As³⁺ and total As accompanied by lower serum vitamin B₁₂ were more likely to have higher odds of GDM (3.12, 95% CI: 1.32, 7.38 and 3.10, 95% CI: 1.30, 7.38, respectively).

CONCLUSIONS

Our data suggest a positive relation between As³⁺ and GDM but a negative relation between As⁵⁺ and GDM. Potential additive interaction of As and OCM with GDM requires further investigation.

Maternal and childhood exposure to inorganic arsenic and airway allergy - A 15-Year birth cohort follow-up study

BACKGROUND

The prevalence of allergic diseases in children has increased globally. Early-life exposure to inorganic arsenic has been found to be associated with impaired immune function and decreased lung function in children; however, the results are inconsistent. We aimed to evaluate the effect of prenatal and childhood exposure to inorganic arsenic on allergic diseases in children, through a 15-year follow-up birth cohort study, conducted in central Taiwan.

METHODS

Children born to women enrolled in the Taiwan Maternal and Infant Cohort Study (TMICS-pilot) from December 2000 to November 2001 were recruited and followed every 2-3 years until the age of 14 years. Urinary specimens were collected in the pregnant women during the 3rd trimester and the followed children. Diagnoses of allergic diseases were based on physician diagnoses using the International Study of Asthma and Allergies in Childhood questionnaire. Urinary arsenic speciation was performed using high-performance liquid chromatography and inductively coupled plasma dynamic reaction cell mass spectrophotometry.

RESULTS

Of the 261 children from 358 mother-infant pairs for this study, those with asthma and allergic rhinitis reported a higher prevalence of maternal allergy (49.47%) than did non-allergic children (29.81%). In the fully adjusted model, levels of maternal urine (iAs + MMA + DMA) greater than the median were found to be significantly associated with an increased risk of asthma (OR = 4.28; 95% CI 1.32, 13.85). Levels of urinary (iAs + MMA + DMA) in children higher than the median were associated with an increased risk of allergic rhinitis (OR = 2.26; 95% CI 1.20, 4.26).

CONCLUSION

Prenatal and childhood exposure to inorganic arsenic were found to be significantly associated with the occurrence of asthma and allergic rhinitis in children, respectively. Further large cohort follow-up studies are important to validate the association between inorganic arsenic exposure and allergic diseases in children.

Insulin resistance and pancreatic β cell dysfunction are associated with thyroid hormone functions: A cross-sectional hospital-based study in Turkey

BACKGROUND AND AIMS

The prevalence of thyroid disease in diabetic patients is significantly higher than the general population. This indicates a possible interaction between thyroid functions and insulin sensitivity. This study aimed to investigate the relationship between insulin resistance (IR), pancreatic β cell function, and thyroid function tests.

METHODS

This cross-sectional study was conducted with adults who applied to Eskişehir Osmangazi University Hospital for general control. Fasting insulin, glucose, TSH, fT3, and fT4 levels in the serum of 1340 adult (18-60 aged) patients without any chronic diseases were examined retrospectively. The fT3/fT4 ratio, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), and HOMA-β values were calculated. The correlation between HOMA-IR and HOMA-β values with thyroid function tests and differences between hormone levels of patients with and without IR were evaluated.

RESULTS

There was a positive correlation between HOMA-IR and TSH, negative with fT4. Also, a positive correlation between HOMA-β and fT3, negative correlation with fT4 were observed. In the IR group, fT3 levels were found significantly higher and fT4 levels were significantly lower. TSH levels were higher in the IR group but not statistically significant. The fT3/fT4 ratio was found significantly higher in the IR group and was correlated positively with both HOMA-IR and HOMA-β.

CONCLUSION

Our results revealed that thyroid dysfunction prevalence is quite high in adults who have not yet been diagnosed with diabetes but have insulin resistance and the onset of pancreatic β cell dysfunction.

Endocrine disruption and obesity: A current review on environmental obesogens

Obesity represents an important public health concern because it substantially increases the risk of multiple chronic diseases and thereby contributing to a decline in both quality of life and life expectancy. Besides unhealthy diet, physical inactivity and genetic susceptibility, environmental pollutants also contribute to the rising prevalence of obesity epidemic. An environmental obesogen is defined as a chemical that can alter lipid homeostasis to promote adipogenesis and lipid accumulation whereas an endocrine disrupting chemical (EDC) is defined as a synthetic chemical that can interfere with the endocrine function and cause adverse health effects. Many obesogens are EDCs that interfere with normal endocrine regulation of metabolism, adipose tissue development and maintenance, appetite, weight and energy balance. An expanding body of scientific evidence from animal and epidemiological studies has begun to provide links between exposure to EDCs and obesity. Despite the significance of environmental obesogens in the pathogenesis of metabolic diseases, the contribution of synthetic chemical exposure to obesity epidemic remains largely unrecognised. Hence, the purpose of this review is to provide a current update on the evidences from animal and human studies on the role of fourteen environmental obesogens in obesity, a comprehensive view of the mechanisms of action of these obesogens and current green and sustainable chemistry strategies to overcome chemical exposure to prevent obesity. Designing of safer version of obesogens through green chemistry approaches requires a collaborative undertaking to evaluate the toxicity of endocrine disruptors using appropriate experimental methods, which will help in developing a new generation of inherently safer chemicals.

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Many environmental obesogens are endocrine disrupting chemicals that interfere with normal endocrine regulation of metabolism.

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Understanding the role of environmental obesogens in the epidemics of obesity is in an infant stage.

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Green chemistry approach aims to design a safer version of these chemicals by understanding their hazardous effects.

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Further studies are necessary to fully establish the hazardous effects of obesogens and their association to human obesity.

Arsenic and fasting blood glucose in the context of other drinking water chemicals: a cross-sectional study in Bangladesh

GOAL

The goal of this study was to evaluate the association between groundwater arsenic and fasting blood glucose in the context of other groundwater chemicals, in Bangladesh.

METHODS

Fasting blood glucose, gender, body mass index, sociodemographic variables, and diabetes medication use were measured among adults ≥ 35 years of age (n = 6587) participating in the Bangladesh Demographic and Health Survey (BDHS) 2011. Groundwater chemicals in 3534 well water samples were measured in the British Geological Survey (BGS) and Department of Public Health Engineering (DPHE) 1998-99 survey. We assigned the nearest BGS-DPHE well's chemical exposure to each BDHS participant. We used survey-estimation linear regression methods to model natural log-transformed fasting blood glucose, among those using groundwater as their primary drinking-water source, as a function of groundwater arsenic. We considered possible interactions between categorical arsenic exposure and each of 14 other groundwater chemicals dichotomized at their medians. The chemicals considered as possible effect modifiers included: aluminum, barium, calcium, iron, potassium, lithium, magnesium, manganese, sodium, phosphorous, silicon, sulfate, strontium, and zinc.

RESULTS

Compared to persons exposed to groundwater arsenic ≤ 10 μg/L, the adjusted geometric mean ratio (GMR) of fasting blood glucose was 1.01 (95% confidence interval: 0.98, 1.04) for individuals exposed to groundwater arsenic concentrations > 10 μg/L and ≤ 50 μg/L, and was 1.01 (0.97, 1.03) for those with > 50 μg/L arsenic. There were no Bonferroni-significant interactions with other chemicals, after accounting for the large number of chemicals tested as modifiers.

CONCLUSIONS

In our analysis of groundwater chemistry data from 1998/99 and fasting blood glucose outcomes measured in nearby populations approximately a decade later, there was no overall association of fasting blood glucose with nearby historical groundwater arsenic. This null association was not significantly modified by the historical levels of other groundwater chemicals. These null results are inconclusive regarding shorter-term potential toxicity of arsenic for glucose regulation, if there are differences between the historical concentrations measured in nearby groundwater and the actual drinking water chemical exposures in the population during the etiologically relevant period for more acute phenotypes like fasting blood glucose. Drinking water supply-relevant, longitudinal exposure assessment with less measurement error is needed to more precisely evaluate the joint impacts of drinking water chemicals and establish if there is a sensitive time window for glycemic outcomes.

Circulating miRNA-126, -145 and -155 levels in Mexican women exposed to inorganic arsenic via drinking water

The aim of this research was to investigate circulating expression levels of three miRNAs (miR-126, miR-155, and miR-145) proposed as predictive CVD biomarkers in Mexican women exposed to inorganic arsenic via drinking water. Mean UAs concentration of 19.5 ± 14.0 μg/g creatinine was found after urine samples were analyzed (n = 105). Significant associations between UAs levels and serum expression levels of miR-155 (p < 0.05) and miR-126 (p < 0.05) were observed after adjustment for assessed co-variables. Alterations in the serum expression levels of miR-155 and miR-126 may be associated with the onset and development of cardiovascular diseases, hence miRNAs could be proposed as prognostic CVD biomarkers. Data found in this study are of concern and risk reduction plans are necessary for the assessed communities to prevent cardiovascular events in this population of women.

The role of arsenic in obesity and diabetes

As many individuals worlwide are exposed to arsenic, it is necessary to unravel the role of arsenic in the risk of obesity and diabetes. Therefore, the present study reviewed the effects of arsenic exposure on the risk and potential etiologic mechanisms of obesity and diabetes. It has been suggested that inflammation, oxidative stress, and apoptosis contribute to the pathogenesis of arsenic-induced diabetes and obesity. Though arsenic is known to cause diabetes through different mechanisms, the role of adipose tissue in diabetes is still unclear. This review exhibited the effects of arsenic on the metabolism and signaling pathways within adipose tissue (such as sirtuin 3 [SIRT3]- forkhead box O3 [FOXO3a], mitogen-activated protein kinase [MAPK], phosphoinositide-dependant kinase-1 [PDK-1], unfolded protein response, and C/EBP homologous protein [CHOP10]). Different types of adipokines involved in arsenic-induced diabetes are yet to be elucidated. Arsenic exerts negative effects on the white adipose tissue by decreasing adipogenesis and enhancing lipolysis. Some epidemiological studies have shown that arsenic can promote obesity. Nevertheless, few studies have indicated that arsenic may induce lipodystrophy. Arsenic multifactorial effects include accelerating birth and postnatal weight gains, elevated body fat content, glucose intolerance, insulin resistance, and increased serum lipid profile. Arsenic also elevated cord blood and placental, as well as postnatal serum leptin levels. The data from human studies indicate an association between inorganic arsenic exposure and the risk of diabetes and obesity. However, the currently available evidence is insufficient to conclude that low-moderate dose arsenic is associated with diabetes or obesity development. Therefore, more investigations are needed to determine biological mechanisms linking arsenic exposure to obesity and diabetes.