Arsenic exposure and type 2 diabetes: results from the 2007-2009 Canadian Health Measures Survey

INTRODUCTION

Inorganic arsenic and its metabolites are considered dangerous to human health. Although several studies have reported associations between low-level arsenic exposure and diabetes mellitus in the United States and Mexico, this association has not been studied in the Canadian population. We evaluated the association between arsenic exposure, as measured by total arsenic concentration in urine, and the prevalence of type 2 diabetes (T2D) in 3151 adult participants in Cycle 1 (2007-2009) of the Canadian Health Measures Survey (CHMS).

METHODS

All participants were tested to determine blood glucose and glycated hemoglobin. Urine analysis was also performed to measure total arsenic. In addition, participants answered a detailed questionnaire about their lifestyle and medical history. We assessed the association between urinary arsenic levels and T2D and prediabetes using multivariate logistic regression while adjusting for potential confounders.

RESULTS

Total urinary arsenic concentration was positively associated with the prevalence of T2D and prediabetes: adjusted odds ratios were 1.81 (95% CI: 1.12-2.95) and 2.04 (95% CI: 1.03-4.05), respectively, when comparing the highest (fourth) urinary arsenic concentration quartile with the lowest (first) quartile. Total urinary arsenic was also associated with glycated hemoglobin levels in people with untreated diabetes.

CONCLUSION

We found significant associations between arsenic exposure and the prevalence of T2D and prediabetes in the Canadian population. Causal inference is limited due to the cross-sectional design of the study and the absence of long-term exposure assessment.

Kidney bioengineering in regenerative medicine: An emerging therapy for kidney disease

The prevalence of end-stage renal disease is emerging as a serious worldwide public health problem because of the shortage of donor organs and the need to take lifelong immunosuppressive medication in patients who receive a transplanted kidney. Recently, tissue bioengineering of decellularization and recellularization scaffolds has emerged as a novel strategy for organ regeneration, and we review the critical technologies supporting these methods. We present a summary of factors associated with experimental protocols that may shed light on the future development of kidney bioengineering and we discuss the cell sources and bioreactor techniques applied to the recellularization process. Finally, we review some artificial renal engineering technologies and their future prospects, such as kidney on a chip and the application of three-dimensional and four-dimensional printing in kidney tissue engineering.

Impact of iron precipitant on toxicity of arsenic in water: a combined in vivo and in vitro study

Removing arsenic (As) from drinking water is widely dependent on iron (Fe)-based coagulation/flocculation techniques. However, little is known about the influence of Fe precipitant on As toxicity. In this present study, the influence of Fe on As toxicity was determined at systems biology level by in vitro and in vivo experiments. In vitro study based on HepG2 cell line found that Fe increased the As toxicity on cell viability and DNA damage, indicating the synergetic toxic effects. However, when the Fe and As were simultaneously exposed to mice by drinking water for 90 days, the results showed that Fe reduced the changes of hepatic transcriptomic profiles and serum and urine metabolic profiles caused by As exposure, showing the antagonistic toxic effects. The antagonistic effects might be because Fe reduced As bioavailability and accumulation, which was verified by As and Fe levels in feces and liver. The results of this study indicate that Fe precipitant can influence the As toxicity. The interactions between As and Fe and their bioavailability might play important roles in the As toxicity. When assessing the safety of As in drinking water, it is necessary to fully consider the combined effects of As and Fe.

Novel ROS-activated agents utilize a tethered amine to selectively target acute myeloid leukemia

This study explores the possible use of reactive oxygen-activated DNA modifying agents against acute myeloid leukemia (AML). A key amine on the lead agent was investigated via cytotoxicity assays and was found necessary for potency. The two best compounds were screened via the NCI-60 cell panel. These two compounds had potency between 200 and 800nM against many of the leukemia cancer cell types. Subsequent experiments explored activity against a transformed AML model that mimics the molecular signatures identified in primary AML patient samples. A lead compound had an IC50 of 760nM against this AML cell line as well as a therapeutic index of 7.7±3 between the transformed AML model cell line and non-cancerous human CD34+ blood stem/progenitor cells (UCB). The selectivity was much greater than the mainstays of AML treatment: doxorubicin and cytarabine. This manuscript demonstrates that this novel type of agent may be useful against AML.

Novel oxidatively activated agents modify DNA and are enhanced by ercc1 silencing

Agents that chemically modify DNA form a backbone of many cancer treatments. A key problem for DNA-modifying agents is lack of specificity. To address this issue, we designed novel molecular scaffolds, termed An-Hq and An-Hq(2), which are activated by a hallmark of some cancers: elevated concentrations of reactive oxygen species. Elevated reactive oxygen species are linked to oncogenesis and are found to increase in several aggressive cancers. The agents are quinones that, upon oxidation, form highly electrophilic species. In vitro studies identified the mode of addition to DNA. The aniline portion of An-Hq serves to enhance nucleophilic addition to the ethyl phenyl ether instead of forming common Michael additions. Structural characterization showed that the agents add to 2'-deoxyguanosine at the N2,N3-positions. The product formed is a bulky hydroxy-N2,3-benzetheno-2'-deoxyguanosine adduct. In addition, the oxidatively activated agents added to 2'-deoxyadenosine and 2'-deoxycytidine but not thymidine or 2'-deoxyinosine. These findings are confirmed by primer extension analysis of a 392 base pair DNA. The full-length primer extension product was reduced by 69.0 ± 0.6% upon oxidative activation of An-Hq(2) as compared to controls. Little sequence dependence was observed with 76% of guanine, adenine, and cytosine residues showing an increase in extension stops between 2- and 4-fold above controls. Benzetheno-nucleobase addition to double-stranded DNA was confirmed by LC/MS of a self-complementary oligonucletide. Experiments were carried out to confirm in vivo DNA damage. Because of the lesion identified in vitro, we reasoned that nucleotide excision repair should be involved in reversing the effects of these oxidatively activated agents and enhance toxicity in Drosophila melanogaster. Using an RNAi-based approach, Ercc1 was silenced, and survival was monitored after injection of an agent. As expected, bulky cross-linking DNA-modifying agents, cisplatin and chlorambucil, showed statistically significant enhanced toxicity in Drosophila with silenced Ercc1. In addition, 5-fluorouracil, which does not produce bulky lesions, showed no selective toxicity. An-Hq and An-Hq(2) showed statistically significant toxicity in Drosophila with silenced Ercc1. Examination of cytotoxicity shows renal carcinoma cell lines as a target of these agents with a median IC(50) of 1.8 μM. Taken together, these data show that the designed oxidatively activated agents form distinct, bulky DNA modifications that prove difficult for cancer cells possessing an elevated reactive oxygen species phenotype to overcome. The modification produced is relatively unique among anticancer agents.