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Objective: We prospectively assessed whether the combined measurements of fasting plasma glucose (FPG) and A1C were effective for predicting type 2 diabetes.Research Design and Methods: Study participants included 6,736 nondiabetic Japanese men aged 40-55 years. Type 2 diabetes was diagnosed in those who had an FPG >or=126 mg/dl or who were being treated with an oral antidiabetic agent or insulin. The models including FPG, A1C, and both were compared using the area under the receiver operating characteristic (AUROC) curves.Results: During the 4-year follow-up period, we confirmed 659 diabetes cases. In multivariate analysis, both FPG and A1C were independently associated with the risk of type 2 diabetes. The model including both FPG and A1C had a greater AUROC curve than that including FPG alone (0.853 vs. 0.818; P < 0.001) or A1C alone (0.853 vs. 0.771; P < 0.001).Conclusions: The combined measurement of FPG and A1C was effective for predicting type 2 diabetes. [ABSTRACT FROM AUTHOR]

Objective: Because skeletal muscle is one of the target tissues for insulin, skeletal muscle mass might be associated with type 2 diabetes. Serum creatinine is a possible surrogate marker of skeletal muscle mass. The purpose of this study was to determine whether serum creatinine level is associated with type 2 diabetes.Research Design and Methods: The study participants were nondiabetic Japanese men (n = 8,570) aged 40-55 years at entry. Type 2 diabetes was diagnosed if fasting plasma glucose was >or=126 mg/dl or if participants were taking oral hypoglycemic medication or insulin.Results: During the 4-year follow-up period, 877 men developed type 2 diabetes. Lower serum creatinine was associated with an increased risk of type 2 diabetes. The multiple-adjusted odds ratio for those who had serum creatinine levels between 0.40 and 0.60 mg/dl was 1.91 (95% CI 1.44-2.54) compared with those who had levels between 0.71 and 0.80 mg/dl.Conclusions: Lower serum creatinine increased the risk of type 2 diabetes. [ABSTRACT FROM AUTHOR]

The article discusses a study on the relationship between walking to work and the development of type 2 diabetes in Japanese men. It mentions that studies revealed that physical activity is effective in preventing diabetes. Men were examined based on their leisure-time physical activity, smoking habits and alcohol intake. The result of the study provided evidence that duration of the walk going to work has an independent effect on the risk of type 2 diabetes.

Cigarette smoking is a risk factor for type 2 diabetes and cardiovascular disease. Not known is whether smoking habit is associated with the risk of developing the metabolic syndrome among men. Study subjects consisted of 7355 Japanese men aged 40 to 55 years without the metabolic syndrome. The metabolic syndrome was defined using modified Adult Treatment Panel III criteria using body mass index in place of waist circumference. Data on smoking habit was obtained from questionnaires. During the 4-year follow-up period, we confirmed 806 cases of the metabolic syndrome. After adjustment for age, body mass index, systolic blood pressure, diastolic blood pressure, triglycerides, HDL cholesterol, fasting plasma glucose, alcohol daily consumption, and physical activity, the odds ratio (OR) of the metabolic syndrome among current smokers was 1.30 (95% confidence interval (CI) 1.04-1.61) in comparison to never smokers. Men who smoked more than 30 cigarettes a day had a higher risk compared with never smokers (OR 1.61, 95% CI 1.16-2.24) (Table 1). To evaluate the chronic effect of cigarettes smoking for the risk of the incidence of the metabolic syndrome, we assessed the relationship between pack-years and the risk of the metabolic syndrome. The value of pack-years is also associated with the increased risk of the metabolic syndrome in a dose-dependent manner. The multiple-adjusted OR for those whose pack-years value is more than 40 is 1.49 (95% CI 1.12-1.98). Furthermore, we assessed the association between cigarettes smoking and the incidence of the components of the metabolic syndrome. Cigarette smoking was associated with the risk of the incidence of hyperglycemia, high triglycerides, and low HDL cholesterol but not high blood pressure or high body mass index. In conclusion, cigarette smoking habit is an independent risk factor for the development of the metabolic syndrome. [ABSTRACT FROM AUTHOR]

Acetoaceto- o -toluidide (AAOT) is made from ortho -toluidine (OTD) and is used for the synthesis of pigments. A report of occupational urinary bladder carcinomas in Japanese workers chronically exposed to OTD and AAOT has recently been published. OTD is a well-known human urinary bladder carcinogen; however, little is known about the toxicity and the carcinogenicity of AAOT. The aim of the present study is to evaluate the toxic effects of AAOT on urinary bladder epithelium. In vitro, the cytotoxicities of AAOT and OTD were evaluated in rat (MYP3) and human (1T1) urothelial cells. The LC50 of AAOT was higher than that of OTD in both MYP cells and 1T1 cells. In vivo, 6-week-old male and female F344 rats were fed diets supplemented with 0%, 1.5%, or 3% AAOT for 4 weeks. Incidences of simple hyperplasia, cell proliferative activity, and γ-H2AX expression, which is a novel marker for the prediction of carcinogenicity, were significantly increased in a dose-dependent manner in the bladder urothelium of male and female rats administered AAOT. Furthermore, in male and female rats administered AAOT, the major urine metabolite of AAOT was OTD. These results demonstrate that AAOT has proliferation-enhancing activity and suggest that OTD metabolized from AAOT may play a pivotal role in the deleterious effects of AAOT in rats. The results of the present study also indicate that AAOT, like other carcinogenic aromatic amines, is likely to be a human bladder carcinogen. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to establish an efficient strategy for screening and surveillance for occupational cholangiocarcinoma. Methods: We evaluated the consecutive changes in laboratory findings during regular health examinations and in abdominal ultrasonography findings before the diagnosis of occupational cholangiocarcinoma in nine patients. The results of laboratory tests and abdominal ultrasonography at the time of diagnosis were also examined. Results: In all patients, the serum γ-glutamyl transpeptidase (γ-GTP) activity increased several years before the diagnosis of cholangiocarcinoma. The serum alanine aminotransferase (ALT) activity also increased several years before the diagnosis, following an increase in the serum aspartate aminotransferase (AST) activity in most patients. Abdominal ultrasonography before the diagnosis revealed regional dilatation of the bile ducts, which continued to enlarge. At the time of diagnosis, the γ-GTP, AST, and ALT activities were increased in nine, seven, and seven patients, respectively. The regional dilatation of bile ducts without tumor-induced stenosis, dilated bile ducts due to tumor-induced stenosis, space-occupying lesions, and/or lymph node swelling were observed. The serum concentrations of carbohydrate antigen 19-9 (CA 19-9) and/or carcinoembryonic antigen (CEA) were increased in all patients. Conclusions: Regular health examinations with a combination of ultrasonography and laboratory tests including the γ-GTP, AST, ALT, CA 19-9, and CEA levels are useful for screening and surveillance for occupational cholangiocarcinoma. [ABSTRACT FROM AUTHOR]

Background Although short sleep duration has been reported to be associated with future cardiometabolic diseases, it is not fully understood whether sleep duration is prospectively associated with the risk of each lipid profile abnormality. Methods Subjects were nondiabetic Japanese, 40–55 years of age, who were not taking oral lipid-lowering medications: for the incidence of low high-density lipoprotein cholesterol (HDL-C), 7627 men with an HDL-C level ≥40 mg/dL; for high triglycerides, 6973 men with a triglyceride level <200 mg/dL; for high low-density lipoprotein cholesterol (LDL-C), 7273 men with an LDL-C level <160 mg/dL; for high non-HDL-C, 7415 men with a non-HDL-C level <190 mg/dL; and for high total cholesterol (TC), 7196 men with a TC level <240 mg/dL. Lipid profile abnormalities were defined according to the Adult Treatment Panel III guidelines of the National Cholesterol Education Program. Results During the 6-year observation period, there were 1022 cases of low HDL-C. Multiple-adjusted hazard ratios for low HDL-C were 0.79 (95% confidence interval, 0.64–0.97) for sleep durations of 5 to <7 h and 0.62 (0.46–0.83) for ≥7 h compared with <5 h. There were 1473 cases of high triglycerides. Multiple-adjusted hazard ratios for high triglycerides were 0.81 (0.68–0.98) for sleep durations of 5 to <7 h and 0.90 (0.72–1.13) for ≥7 h compared with <5 h. However, no association between sleep duration and the risk of future high LDL-C, non-HDL-C, or TC was observed. Conclusions Moderate and/or long sleep durations decreased the risk of future low HDL-C and high triglycerides. [ABSTRACT FROM AUTHOR]

Objective Butyrylcholinesterase is synthesized in the liver. The serum butyrylcholinesterase level has been cross-sectionally reported to be higher in patients with diabetes, hyperlipidaemia, obesity and fatty liver than in those without them. It is not known whether serum butyrylcholinesterase is associated with the risk of future type 2 diabetes. Design A prospective cohort study. Participants A total of 8470 Japanese men aged 40-55 years without type 2 diabetes at baseline. Measurements Type 2 diabetes was diagnosed if a fasting plasma glucose ( FPG) level was ≥7·0 mmol/l, if a HbA1c level was ≥6·5% or if participants were taking oral hypoglycaemic medication or insulin. Results During the 42 227 person-years of follow-up, 868 cases had developed type 2 diabetes. Serum butyrylcholinesterase was significantly positively correlated with body mass index ( BMI), FPG, alanine aminotransferase ( ALT), γ-glutamyltransferase ( GGT) and triglycerides ( TG), whereas negatively with high-density lipoprotein ( HDL) cholesterol. In Cox proportional hazards models, after adjusting for age, BMI, FPG, alcohol consumption, smoking habit, walk to work, regular leisure-time physical activity and family history of diabetes, the highest quartile (398-806 IU/l) of serum butyrylcholinesterase increased the risk of type 2 diabetes compared with the lowest quartile (56-311 IU/l) [hazard ratio ( HR) 1·41 (95% confidence interval ( CI), 1·14-1·74)]. After further adjusting for ALT and GGT, this association remained [ HR 1·40 (95% CI, 1·13-1·73)]. Furthermore, this association was significant independent of TG and HDL cholesterol. Conclusions Elevated serum butyrylcholinesterase was independently associated with an increased risk of future type 2 diabetes. [ABSTRACT FROM AUTHOR]

Aim: The prevalence of underweight women, who have an increased risk for small-for-gestational-age (SGA) birth, is increasing in Japan. We examined the associations of pre-pregnancy body mass index and gestational weight gain (GWG) with SGA birth among Japanese women. Material and Methods: We conducted a prospective cohort study of 1391 women who delivered full-term singleton babies. SGA was defined as below the 10th percentile of birthweight at each gestational age, baby sex, and parity. We calculated the 5th percentile of birthweight in the same way for another threshold for SGA. According to pre-pregnancy body mass index, we divided the participants into three groups: underweight (<18.5 kg/m2), normal weight (18.5-24.9 kg/m2), and overweight and obese (≥25.0 kg/m2). Results: SGA birth was observed most frequently among the underweight group (13.8%). Underweight was associated with an increased risk of SGA birth. The multiple-adjusted odds ratio for underweight was 1.96 (95% confidence interval, 1.23-3.11) compared with normal weight. Sufficient GWG reduced the incidence and the multiple-adjusted odds ratio for 1-kg increase of GWG was 0.86 (0.81-0.92). The same tendency was observed for the delivery of infants below the 5th birthweight percentile. Women with underweight and normal weight who had 9.0 kg or less of GWG had a significantly higher risk of SGA birth than women with normal weight who had 9.1-11.0 kg of GWG. Conclusions: Underweight and poor GWG were associated with a higher incidence of SGA birth. However, the incidence of SGA birth among underweight women was not increased significantly if they had sufficient GWG. [ABSTRACT FROM AUTHOR]

Tonsillectomy is being frequently used in Japan, while Western nephrologists are more reluctant to adopt tonsillectomy as a treatment for IgAN…(In this issue of NDT) Isseki et al. report the outcome of 200 Japanese patients with biopsy-proven IgAN followed in mean for up to 7 years after renal biopsy.Background Indication of tonsillectomy in IgA nephropathy is controversial. The purpose of this study was to examine the efficacy of tonsillectomy on remission and progression of IgA nephropathy. Methods We conducted a single-center 7-year historical cohort study in 200 patients with biopsy-proven IgA nephropathy. Study outcomes were clinical remission defined as disappearance of urine abnormalities at two consecutive visits, glomerular filtration rate (GFR) decline defined as 30% GFR decrease from baseline and GFR slope during the follow-up. Results Seventy of the 200 patients received tonsillectomy. Tonsillectomy was associated with increased incidence of clinical remission (P + 0.01, log-rank test) and decreased incidence of GFR decline (P = 0.01, log-rank test). After adjustment for age and gender, hazard ratios in tonsillectomy were 3.90 (95% confidence interval 2.46–6.18) for clinical remission and 0.14 (0.02–1.03) for GFR decline. After further adjustment for laboratory (baseline mean arterial pressure, GFR, 24-h proteinuria and hematuria score), histological (mesangial score, segmental sclerosis or adhesion, endocapillary proliferation and interstitial fibrosis) or treatment variables (steroid and renin–angiotensin system inhibitors), similar results were obtained in each model. Even after exclusion of 69 steroid-treated patients, results did not change. GFR slopes in tonsillectomy and non-tonsillectomy groups were 0.60 ± 3.65 and − 1.64 ± 2.59 mL/min/1.73 m2/year, respectively. In the multiple regression model, tonsillectomy prevented GFR decline during the follow-up period (regression coefficient 2.00, P = 0.01). Conclusion Tonsillectomy was associated with a favorable renal outcome of IgA nephropathy in terms of clinical remission and delayed renal deterioration even in non-steroid-treated patients. [ABSTRACT FROM PUBLISHER]

OBJECTIVE--It has been reported that moderate alcohol consumption decreased the risk of type 2 diabetes but that elevated liver enzymes increased it. The comparative importance of alcohol consumption and liver enzymes as predictors of type 2 diabetes remains unconfirmed. RESEARCH DESIGN AND METHODS--The participants included 8,576 Japanese men, aged 40-55 years, without type 2 diabetes at entry. Type 2 diabetes was diagnosed if a fasting plasma glucose level was ≥126 mg/dl or if participants were taking oral hypoglycemic medications or insulin. RESULTS--During the 4-year follow-up period, we confirmed 878 cases. In multivariate models, moderate daily alcohol consumption (16.4-42.6 g ethanol/day) decreased the risk of type 2 diabetes, and higher levels of γ-glutamyhransferase (GGT) and alanine aminotransferase (ALT) increased the risk. In joint analyses of alcohol consumption and liver enzymes, moderate drinkers with the lowest tertile of GGT had the lowest risk of type 2 diabetes. Compared with them, nondrinkers with the highest GGT had the highest risk of type 2 diabetes (odds ratio 3.18 [95% CI 1.75-5.76]). At every level of GGT, moderate or heavy alcohol drinkers (≥42.7 g ethanol/day) had a lower risk of type 2 diabetes than nondrinkers. The relationship of ALT and daily alcohol consumption with the risk of type 2 diabetes was almost the same as that of GGT. CONCLUSIONS--GGT, ALT, and daily alcohol consumption were independently associated with the risk of type 2 diabetes. Nondrinkers with the highest GGT or ALT had a high risk of type 2 diabetes. [ABSTRACT FROM AUTHOR]

Abstract: A new clinical syndrome with prominent cerebellar symptoms in patients living in Kamisu City, Ibaraki Prefecture, Japan, is described. Since the patients ingested drinking water containing diphenylarsinic acid (DPA), a stable degradation product of both diphenylcyanoarsine and diphenylchloroarsine, which were developed for use as chemical weapons and cause severe vomiting and sneezing, DPA was suspected of being responsible for the clinical syndrome. The purpose of the present study was to elucidate prominent cerebellar symptoms due to DPA. The aim of the study was to determine if single (15 mg/kg) or continuous (5 mg/kg/day for 5 weeks) oral administration of DPA to ICR-strain mice induced oxidative and/or nitrosative stress in their brain. Significantly positive staining with malondialdehyde (MDA) and 3-nitrotyrosine (3-NT) was observed in the cerebellar Purkinje cells by repeated administration (5 mg/kg/day) with DPA for 5 weeks that led to the cerebellar symptoms from a behavioral pharmacology standpoint and by single administration of DPA (15 mg/kg). Furthermore, it is possible that the production of 3-NT was not caused by peroxynitrite formation. The present results suggest the possibility that arsenic-associated novel active species may be a factor underlying the oxidative and nitrosative stress in Purkinje cells due to exposure to DPA, and that the damage may lead to the cerebellar symptoms. [Copyright &y& Elsevier]

Abstract: An analytical method using a combination of solid-phase extraction (SPE) and gas chromatography with a flame thermionic detector (GC/FTD) was developed for determination of N-methyl-2-pyrrolidone (NMP), N-methylsuccinimide (MSI), and 2-hydroxy-N-methylsuccinimide (2-HMSI) in human urine. The SPE cartridge of poly(divinylbenzene/hydroxymethacrylate) used was directly loaded with urine sample, followed by elution with methyl isobutyl ketone (MIBK) and subsequent centrifugation, and the supernatant was injected into the capillary GC using a DB1701. This method allowed efficient separation of NMP, MSI, and 2-HMSI, which were nearly free of interference by other GC peaks arising from urine. Recoveries of NMP, MSI, and 2-HMSI from the SPE cartridge were about 98, 101, and 67%, respectively, with limits of detection of 0.04, 0.02, and 0.06mg/L, respectively, which met the regulatory requirements. The present method was used for assay in biological monitoring of workers exposed to NMP in their occupational environment. [Copyright &y& Elsevier]

Abstract: Epidemiological studies indicated that human arsenic exposure can induce urinary bladder cancer. Methylation of inorganic arsenic can generate more reactive and toxic organic arsenical species. In this regard, it was recently reported that the methylated arsenical metabolite, dimethylarsinic acid [DMA(V)], induced urinary bladder tumors in rats. However, other methylated metabolites, like monomethylarsonic acid [MMA(V)] and trimethylarsine oxide (TMAO) were not carcinogenic to the urinary bladder. In order to compare the early effects of DMA(V), MMA(V), and TMAO on the urinary bladder transitional cell epithelium at the scanning electron microscope (SEM) level, we investigated the sub-chronic (13 weeks) toxicological effects of MMA(V) (187 ppm), DMA(V) (184 ppm), TMAO (182 ppm) given in the drinking water to male and female F344 rats with a focus on the urinary bladder in this study. Obvious pathological changes, including ropy microridges, pitting, increased separation of epithelial cells, exfoliation, and necrosis, were found in the urinary bladders of both sexes, but particularly in females receiving carcinogenic doses of DMA(V). Urine arsenical metabolic differences were found between males and females, with levels of MMA(III), a potential genotoxic form, higher in females treated with DMA(V) than in males. Thus, this study provides clear evidence that DMA(V) is more toxic to the female urinary bladder, in accord with sensitivity to carcinogenesis. Important gender-related metabolic differences including enhanced presentation of MMA(III) to the urothelial cells might possibly account for heightened sensitivity in females. However, the potential carcinogenic effects of MMA(III) need to be further elucidated. [Copyright &y& Elsevier]

This study presents the research on the chemical analysis and genotoxicity of 28 virgin/recycled paper products in food-contact use. In the chemical analysis, paper products were extracted by reflux with ethanol, and analyzed by gas chromatography/mass spectrometry. 4,4′-bis(dimethylamino)benzophenone (Michler''s ketone: MK), 4,4′-bis(diethylamino)benzophenone (DEAB), 4-(dimethylamino)benzophenone (DMAB) and bisphenol A (BPA) were found characteristically in recycled products. Seventy-five percent of the recycled paper products contained MK (1.7–12 μg/g), 67% contained DEAB (0.64–10 μ g/g), 33% contained DMAB (0.68–0.9 μg/g) and 67% contained BPA (0.19–26 μg/g). Although, BPA was also detected in virgin paper products, the detection levels in the recycled products were ten or more times higher than those in the virgin products. The genotoxicity of paper and paperboard extracts and compounds found in them were investigated by Rec-assay and comet assay. Of the 28 products tested by Rec-assay using Bacillus subtilis, 13 possessed DNA-damaging activity. More recycled than virgin products (75% against 25%) exhibited such activity, which, of the compounds, was observed in BPA, 1,2-benzisothiazoline-3-one (BIT), 2-(thiocyanomethylthio)benzothiazole, 2,4,5,6-tetrachloro-isophthalonitrile, 2,4,6-trichlorophenol (TCP), and pentachlorophenol. The critical toxicant in one virgin paper product was concluded to be BIT. Eight samples with DNA-damaging activity were also tested by comet assay using HL-60 cells; six induced comet cells significantly (five times or higher than the control) without a decrease of viable cells. TCP, BZ, DEAB, and BIT also caused a slight increase in comet cells. In conclusion, we showed that most recycled paper products contain chemicals such as MK, DEAB, DMAB, and BPA, and possess genotoxicity. However, the levels of the chemicals in the recycled products could not explain their genotoxic effects. [Copyright &y& Elsevier]

Dimethylarsinic acid [DMA, (CH3)2AsO(OH)] causes cancer in the urinary bladder of rats. However, its mechanism of cancer or the ultimate carcinogenic form is not yet known. Rats administered dimethylarsinic acid excrete three unknown arsenic compounds (termed M-1, M-2, and M-3) in urine or feces, and these compounds are presumed to be produced by intestinal bacteria. Escherichia coli A3-6 isolated from a rat yielded two unknown arsenic compounds (M-2 and M-3) from dimethylarsinic acid and M-1 from trimethylarsine oxide (TMAO) in the presence of cysteine (Cys). Contents of M-2 and M-3 varied with cysteine concentration. The cytotoxicity and genotoxicity of the bacteria-free solution of dimethylarsinic acid or trimethylarsine oxide metabolized by E. coli A3-6 were studied using V79 cells. Dimethylarsinic acid (1 mM) metabolized by E. coli A3-6 in the presence of cysteine (1 mM) was highly cytotoxic (50% survival reduction concentration; 2.1 μM As) in V79 cells, and the toxic substance appeared to be M-2. The metabolite solution (at 2.5–10 μM total As) induced c-mitosis and tetraploids, and caused mitotic arrest, since it increased mitotic cells at the cytotoxic dose. The metabolite solution also significantly increased sister chromatid exchange (SCE) and chromosomal aberrations, most of which were chromatid gaps and chromatid breaks. A3-6 converted 96.1% of trimethylarsine oxide to M-1 in the presence of cysteine. This metabolite solution did not exhibit cytotoxicity or genotoxicity. The reported M-2 concentration in urine of rats administered levels of DMA via drinking water known to cause bladder tumors was sufficient to exhibit cytotoxic and genotoxic effects in urinary bladder. Thus, we hypothesize that intestinal bacteria play an important role in carcinogenicity of dimethylarsinic acid. [Copyright &y& Elsevier]

Although numerous epidemiological studies have indicated that human arsenic exposure is associated with increased incidences of bladder, liver, skin, and lung cancers, limited attempts have been made to understand mechanisms of carcinogenicity using animal models. Dimethylarsinic acid (DMA), an organic arsenic compound, is a major metabolite of ingested inorganic arsenics in mammals. Recent in vitro studies have proven DMA to be a potent clastogenic agent, capable of inducing DNA damage including double strand breaks and cross-link formation. In our attempts to clarify DMA carcinogenicity, we have recently shown carcinogenic effects of DMA and its related metabolites using various experimental protocols in rats and mice: (1) a multi-organ promotion bioassay in rats; (2) a two-stage promotion bioassay by DMA of rat urinary bladder and liver carcinogenesis; (3) a 2-year carcinogenicity test of DMA in rats; (4) studies on the effects of DMA on lung carcinogenesis in rats; (5) promotion of skin carcinogenesis by DMA in keratin (K6)/ornithine decarboxylase (ODC) transgenic mice; (6) carcinogenicity of DMA in p53(+/-) knockout and Mmh/8-OXOG-DNA glycolase (OGG1) mutant mice; (7) promoting effects of DMA and related organic arsenicals in rat liver; (8) promoting effects of DMA and related organic arsenicals in a rat multi-organ carcinogenesis test; and (9) 2-year carcinogenicity tests of monomethylarsonic acid (MMA) and trimethylarsine oxide (TMAO) in rats. The results revealed that the adverse effects of arsenic occurred either by promoting and initiating carcinogenesis. These data, as covered in the present review, suggest that several mechanisms may be involved in arsenic carcinogenesis. [Copyright &y& Elsevier]

A method for the determination of trivalent arsenicals in urine was examined. Trivalent arsenicals, extracted as complexes with diethylammonium diethyldithiocarbamate (DDDC) into carbon tetrachloride, were determined by liquid chromatography–inductively coupled plasma mass spectrometry (LC–ICP-MS). The trivalent methylated arsenicals monomethylarsonous acid (MMA(III)), dimethylarsinous acid (DMA(III)), and trimethylarsine (TMA) were detected in urine of rats that had received dimethylarsinic acid (DMA(V)) or monomethylarsonic acid (MMA(V)) at concentration of 200 μg ml−1 in drinking water for 24 weeks. This method is the first to permit quantification of trivalent methylated arsenicals in urine without significant changes in concentration during storage or pretreatment. [Copyright &y& Elsevier]

Presents a study which investigated the relationship between daily alcohol consumption and the risk of type 2 diabetes in a large Japanese cohort. Research design and methods; Results; Conclusions.

Presents information on a study regarding the effect of impaired fasting glucose (IFG) in increasing the risk of hypertension on Japanese cohorts during 1980 and 1990. Diagnosis of diabetes, IFG and hypertension; Biochemical measurements and clinical characteristics of the study; Result and discussion.

Objectives: We aimed to develop a method to determine workers' personal exposure levels to N-(phosphonomethyl)glycine (glyphosate) for their risk assessments., Methods: The proposed method was assessed as follows: recovery, stability of samples on storage, method limit of quantification, and reproducibility. Glyphosate in air was sampled using an air-sampling cassette containing a glass fiber filter. Ultrapure water was used to extract glyphosate from sampler filters. After derivation with 9-fluorenylmethyloxycarbonyl chloride, samples were analyzed by high-performance liquid chromatography using a fluorescence detector., Results: Spiked samples indicated an overall recovery of 101%. After 7 days of storage at 4°C, recoveries were approximately 100%. The method limit of quantification was 0.060 μg/sample. Relative standard deviations representing overall reproducibility, defined as precision, were 1.4%-1.8%., Conclusions: The method developed in this study allows 4-h personal exposure monitoring of glyphosate at 0.250-500 μg/m 3 . Thus, this method can be used to estimate worker exposure to glyphosate., (© 2022 The Authors. Journal of Occupational Health published by John Wiley & Sons Australia, Ltd on behalf of The Japan Society for Occupational Health.)

Seaweeds contain large amounts of organoarsenic compounds, mostly arsenosugars (AsSug) and arsenolipids (AsLipid). AsSug is mainly metabolized into dimethylarsinic acid (DMA V ) in humans. However, this metabolic process is not well understood. We investigated the metabolism of an AsSug, 3-[5'-deoxy-5'-(dimethylarsinoyl)-β-ribofuranosyloxy]-2-hydroxypropylene glycol (AsSug328), in the gastrointestinal tract using an in vitro artificial gastrointestinal digestion system. AsSug328 was incubated with gastric juice for 4 h, with bile-pancreatic juice for 0.5 h, and finally with enteric bacteria solution for 24 h. The conversion of arsenic compounds after artificial digestion was analyzed by HPLC-ICP-MS and HPLC-ESI-Q-TOF-MS. Our results show that artificial gastrointestinal digestion converted AsSug328 into thio-AsSug328. However, no formation of DMA V was detected. Under the artificial digestion system, the 5-deoxyribofuranose structure of AsSug was maintained. Therefore, AsSug should be absorbed in the intestinal tract after its sugar moiety is partially decomposed. They are then possibly metabolized to DMA V in the liver and subsequently excreted through urine.

Objectives: The purpose of this study was to develop a simple and accurate gas chromatography-mass spectrometry (GC-MS) method for simultaneous determination of four urinary metabolites from four organic solvents, that is, hippuric acid (HA) from toluene, methylhippuric acid (MHA) from xylene, and mandelic acid (MA) and phenylglyoxylic acid (PGA) from styrene or ethylbenzene for biological monitoring., Methods: The four metabolites were directly methyl-esterified with 2,2-dimethoxypropane and analyzed using GC-MS. The proposed method was validated according to the US Food and Drug Administration guidance. The accuracy of the proposed method was confirmed by analyzing a ClinChek ® -Control for occupational medicine (RECIPE Chemicals +Instruments GmbH)., Results: Calibration curves showed linearity in the concentration range of 10-1000 mg/L for each metabolite, with correlation coefficients >0.999. For each metabolite, the limits of detection and quantification were 3 mg/L and 10 mg/L, respectively. The recovery was 93%-117%, intraday accuracy, expressed as the deviation from the nominal value, was 92.7%-103.0%, and intraday precision, expressed as the relative standard deviation (RSD), was 1.3%-4.7%. Interday accuracy and precision were 93.4%-104.0% and 1.2%-9.5%, respectively. The analytical values of ClinChek obtained using the proposed method were sufficiently accurate., Conclusions: The proposed method is a simple and accurate which is suitable for routine analyses that could be used for biological monitoring of occupational exposure to four organic solvents., (© 2019 The Authors. Journal of Occupational Health published by John Wiley & Sons Australia, Ltd on behalf of The Japan Society for Occupational Health.)

Dimethylmonothioarsinical acid (DMMTA V ), a metabolite of arsenosugars (AsSug) and arsenolipids (AsLP), which are major organoarsenicals contained in seafoods, has been a focus of our attention due to its toxicity. It has been reported that the toxicity of DMMTA V differs according to the host cell type and that dimethylarsinous acid (DMA III ), which is a higher active metabolite of inorganic and organo arsenic compounds, may be the ultimate substance. To further elucidate the details of the mechanisms of DMMTA V , we carried out toxicological characterization by comparing DMMTA V and DMA III using HepaRG cells, which are terminally differentiated hepatic cells derived from a human hepatic progenitor cell line that retains many characteristics, e.g, primary human hepatocytes including the morphology and expression of key metabolic enzymes (P450 s and GSTs, etc.) and complete expression of all nuclear receptors. HepaRG cells were induced to undergo differentiation by DMSO, which result red in increased levels of metabolic enzymes such as P450 and GST, in non-differentiated cells the cellular toxicities of DMMTA V and DMA III were reduced and the induction of toxicity by DMMTA V was increased by GSH but not by DMA III . Both DMA III and DMMTA V induce apoptosis and increase caspase 3/7 activity. DMA III exposure increased the activity of caspase-9. On the contrary, DMMTA V exposure resulted in markedly elevated activity of caspase-8 as well as caspase-9. These results suggest there are differences between the signaling pathways of apoptosis in DMA III and DMMTA V and that between their active metabolites. Consequently, the ultimate metabolic substance of toxicity induction of DMMTA V may not only be DMA III , but may also be partly due to other metabolic substances produced through the activation mechanism by GSH., (Copyright © 2018. Published by Elsevier GmbH.)

Objectives: This study aimed to evaluate the relationship between cumulative exposure to 1,2-dichloropropane (1,2-DCP) and incidence risk of cholangiocarcinoma among workers in the offset proof-printing section of a small printing company in Osaka, Japan., Methods: We identified 95 workers of a printing company (78 men and 17 women) who had been exposed to 1,2-DCP between 1987 and 2006, and calculated the standardised incidence ratio (SIR) of cholangiocarcinoma from 1987 to 2012. We estimated cumulative exposure to 1,2-DCP and calculated SIRs in four exposure categories. We also calculated incidence rate ratios (RRs) adjusted by sex, age, calendar year and dichloromethane (DCM) exposure for three exposure categories using Poisson regression analysis., Results: Cumulative exposures to 1,2-DCP ranged from 32 to 3433 ppm-years (mean, 851 ppm-years) and the SIR was 1171 (95% CI 682 to 1875). In the analysis of the four exposure categories, SIRs increased significantly in the three highest exposure categories, but not in the lowest category. Adjusted RRs in the middle and high exposure categories were 14.9 (95% CI 4.1 to 54.3) and 17.1 (95% CI 3.8 to 76.2), respectively, in the analysis without lag time, and were 11.4 (95% CI 3.3 to 39.6) and 32.4 (95% CI 6.4 to 163.9), respectively, in the analysis with a 5-year lag. The trend analysis revealed a significant increase in RR in association with increasing cumulative exposure to 1,2-DCP. DCM exposure was not significantly associated with the development of cholangiocarcinoma., Conclusions: The present study demonstrated an exposure-response relationship between exposure to 1,2-DCP and the development of cholangiocarcinoma., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

The purpose of the present study was to elucidate the metabolic processing of dimethylmonothioarsinic acid (DMMTA(V)), which is a metabolite of inorganic arsenic and has received a great deal of attention recently due to its high toxicity. The metabolites produced from an in vitro reaction with GSH were analyzed by high performance liquid chromatography-time of flight mass spectrometer (HPLC-TOFMS), HPLC with a photodiode array detector (PDA), and also gas chromatography-mass spectrometry (GC-MS) and GC with a flame photometric detector (FPD). The reaction of dimethylarsinic acid (DMA(V)) with GSH did not generate DMA(V)-SG but did generate dimethylarsinous acid (DMA(III)) or DMA(III)-SG. On the contrary, we confirmed that the reaction of DMMTA(V) with GSH directly produced the stable complex of DMMTA(V)-SG without reduction through a trivalent dimethylated arsenic such as DMA(III) and DMA(III)-SG. Furthermore, the present study suggests the production of hydrogen sulfide (H2S) and dimethylmercaptoarsine (DMA(III)-SH), a trivalent dimethylated arsenic, as well as DMA(III) and DMA(III)-SG in the decomposition process of DMMTA(V)-SG. These results indicate that the toxicity of DMMTA(V) depends not only on the formation of DMA(III) but also on at least those of H2S and DMA(III)-SH., (Copyright © 2015 Elsevier GmbH. All rights reserved.)

The International Agency for Research on Cancer (IARC) has concluded that dimethylarsinic acid [(CH3)2AsO(OH), DMA(V)], a main metabolite of inorganic arsenic, is responsible for carcinogenesis in urinary bladder and lung in rodents, and various modes of carcinogenic action have been proposed. One theory concerning the mode of action is that the biotransformation of dimethylarsinous acid [(CH3)2AsOH, DMA(III)] from DMA(V) plays an important role in the carcinogenesis by way of reactive oxygen species (ROS) production. Furthermore, dimethylmonothioarsinic acid [(CH3)2AsS(OH), DMMTA(V)], a metabolite of DMA(V), has also been noted because of its higher toxicity. However, the metabolic mechanisms of formation and disappearance of DMA(III) and DMMTA(V), and their toxicity are not fully understood. Thus, the purpose of the present study was to clarify the mechanism of metabolic formation of DMMTA(V) and DMA(V) from DMA(III). The in vitro transformation of arsenicals by treatment with liver homogenate from rodents and sulfur transferase was detected by HPLC-ICP-MS and HPLC-tandem MS. DMMTA(V) is produced from DMA(III) but not DMA(V) by cellular fractions from mouse liver homogenates and by rhodanese from bovine liver in the presence of thiosulfate, a sulfur donor. Not only DMMTA(V) thus produced but also DMA(III) are re-converted into DMA(V) by an in vitro addition of S9 mix. These findings indicate that the metabolic process not only of DMA(III) to DMA(V) or DMMTA(V) but also of DMMTA(V) to DMA(V) consists of a complicated mode of interaction between monooxygenase including cytochrome P450 (CYP) and/or sulfur transferase., (Copyright © 2014 Elsevier GmbH. All rights reserved.)

Background: Cholangiocarcinoma has been reported in workers exposed to chlorinated organic solvents and has consequently been classified as an occupational disease (occupational cholangiocarcinoma) by the Japanese Ministry of Health, Labour and Welfare. This study aimed to identify the characteristics of nine workers newly diagnosed with occupational cholangiocarcinoma., Methods: This study was a retrospective study conducted in 13 hospitals and three universities. Clinicopathological findings of nine occupational cholangiocarcinoma patients from seven printing companies in Japan were investigated and compared with 17 cholangiocarcinoma patients clustered in a single printing company in Osaka., Results: Patient age at diagnosis was 31-57 years. Patients were exposed to 1,2-dichloropropane and/or dichloromethane. Serum γ-glutamyl transpeptidase activity was elevated in all patients. Regional dilatation of the intrahepatic bile ducts without tumor-induced obstruction was observed in two patients. Four patients developed intrahepatic cholangiocarcinoma and five developed hilar cholangiocarcinoma. Biliary intraepithelial neoplasia and/or intraductal papillary neoplasm of the bile duct was observed in four patients with available operative or autopsy specimens., Conclusions: Most of these patients with occupational cholangiocarcinoma exhibited typical findings, including high serum γ-glutamyl transpeptidase activity, regional dilatation of the bile ducts, and precancerous lesions, similar to findings previously reported in 17 occupational cholangiocarcinoma patients in Osaka., (© 2014 Japanese Society of Hepato-Biliary-Pancreatic Surgery.)

Background: An outbreak of cholangiocarcinoma occurred among workers in the offset color proof-printing department at a printing company in Japan. The aim of this study was to clarify the characteristics of the patients with cholangiocarcinoma., Methods: This was a retrospective study conducted in 13 Japanese hospitals between 1996 to 2013. The clinicopathological findings of cholangiocarcinoma developed in 17 of 111 former or current workers in the department were investigated. Most workers were relatively young., Results: The cholangiocarcinoma was diagnosed at 25-45 years old. They were exposed to chemicals, including dichloromethane and 1,2-dichloropropane. The serum γ-glutamyl transpeptidase activity was elevated in all patients. Dilated intrahepatic bile ducts without tumor-induced obstruction were observed in five patients. The cholangiocarcinomas arose from the large bile ducts. The precancerous or early cancerous lesions, such as biliary intraepithelial neoplasia and intraductal papillary neoplasm of the bile ducts, as well as non-specific bile duct injuries, such as fibrosis, were observed in various sites of the bile ducts in all eight patients for whom operative specimens were available., Conclusions: The present results showed that cholangiocarcinomas occurred at a high incidence in relatively young workers of a printing company, who were exposed to chemicals including chlorinated organic solvents., (© 2014 Japanese Society of Hepato-Biliary-Pancreatic Surgery.)

This study describes the history of the occupational diseases and the preventive measures by the laws in Japan. The first serious occupational diseases occurred in mining industry in the late 19th century because the working conditions were inferior. The mining industry ordinance was enforced in 1890 as the first law that prescribed working conditions, safety and health, and injury compensation. The most serious infection disease was tuberculosis, and the mortality was 180-260 per 100,000 during 1903-45. Since the prohibition on asbestos was late for 2006, the outbreak of asbestos-related diseases will continue until 2070. Although occupational poisonings have significantly decreased, unregulated chemicals recently caused many cases of cholangiocarcinoma among offset printing workers. Mental health disorders have been increasing in the various working places indicating stressful environment.

Objectives: An outbreak of neurological health disorder caused by drinking well water occurred in 2003 at one apartment building in Kamisu, Ibaraki, Japan. This was the first case of mass poisoning due to well water contaminated with diphenylarsinic acid (DPAA). Subsequently, other residents in Kamisu were confirmed to have drunk well water containing lower concentrations of DPAA. The present study aimed to investigate neurological and other subjective symptoms and miscarriage occurrences after DPAA exposure., Methods: Subjects were residents of Kamisu aged 10-65 years in 2004. Twenty residents (high-level exposure group) had lived in the apartment building and drunk well water containing DPAA at arsenic concentrations of 2,262 μg/L. The moderate/low-level exposure group (67 residents) had drunk other well water containing DPAA at arsenic concentrations of 2-230 μg/L (mean: 85 μg/L) and DPAA was detected in their hair or nails. A control group (134 residents), matched to the latter group by sex and age, had only drunk tap water. Public health nurses completed a questionnaire on symptoms, pregnancy, and miscarriage through interviews., Results: Dizziness, unsteadiness, dysesthesia, writing disturbance, diplopia, insomnia, melancholy, headache, itchiness, weight change, diarrhea, cough, and dyspnea were significantly higher in the moderate/low-level exposure group than in the control group. A similar tendency was found in the high-level exposure group. From 1999 through 2003, no miscarriages occurred among 15 pregnancies in the control group, while three miscarriages occurred among five pregnancies in the moderate/low-level group., Conclusion: DPAA exposure via well water caused miscarriage, in addition to neurological and other subjective symptoms.

The incidence of cholangiocarcinoma among the past or present workers in the department of offset color proof-printing at a printing company in Osaka was extremely high. The workers were relatively young and were exposed to several chemicals including organic solvents such as dichloromethane and 1,2-dichloropropane. Although the exact cause of cholangiocarcinoma in the patients remain unknown, it is likely that the development of cholangiocarcinoma was triggered during exposure to these chemicals. Some chemicals can act as environmental factors that lead to the development of cholangiocarcinoma. Therefore, we believe that cholangiocarcinoma is a new type of occupational cancer.

Background: Moderate alcohol consumption is associated with a decreased risk of type 2 diabetes. However, the relationship between drinking patterns, such as the weekly frequency of alcohol consumption and the quantity per drinking day, and the incidence of type 2 diabetes has not been sufficiently addressed., Methods: Study participants included 10 631 Japanese men aged 40-55 years without type 2 diabetes at entry. Type 2 diabetes was diagnosed if a fasting plasma glucose level was ≥7.0 mmol/l or if participants were taking diabetes medications. Data on alcohol consumption were obtained from questionnaires., Results: During the 37 172 person-years of follow-up, we confirmed 878 cases of type 2 diabetes. Frequent alcohol consumption was associated with a low risk of type 2 diabetes. Compared to non-drinkers, the multiple-adjusted HR for those who drank 4-7 days weekly was 0.76 (95% CI, 0.63 to 0.92). To assess the association between drinking pattern and type 2 diabetes, we examined the joint association of the weekly frequency and the quantity per drinking day with type 2 diabetes. Men who consumed 0.1-2.0 or 2.1-4.0 US standard drinks per drinking day on 4-7 days weekly had a lower risk of type 2 diabetes (HR 0.74, 95% CI 0.58 to 0.95; HR 0.74, 95% CI 0.60 to 0.91, respectively) compared to non-drinkers., Conclusions: More frequent alcohol consumption lowered the risk of type 2 diabetes. Light to moderate alcohol consumption per drinking day on 4-7 days weekly lowered the risk of type 2 diabetes compared to non-drinkers.

Background: Daphnia magna is a useful aquatic organism for testing ecological toxicities of environmental pollutants. However, there were only a few studies on agricultural chemicals using these organisms., Methods: We investigated acute and subchronic toxicities of 30 agricultural chemicals commonly used in Japan in D. magna. Acute toxicity of the agricultural chemicals was determined using the concentrations yielding 50% immobility of D. magna after 24 hr and 48 hr exposure as end points. D. magna was cultivated with the chemical and algae until the first brood production. Lethal toxicity and the number of survival broods were determined within 13 days., Results: All insecticides among the agricultural chemicals exhibited the strongest acute toxicity (LC50 from 0.00053 to 0.037 mg/L). More than 50% of the herbicides and fungicides did not exhibit acute toxicity at 10 mg/L. Chlornitrofen, pencycuron, and fenitrothion showed significantly lower LC50 values at 8 days than at 24 hr and 48 hr. Isoprothiolane, flutolanil, and thiophanatemethyl significantly delayed the first brood at concentrations less than half of those for LC50 (8 days). Thiobencarb, iprodione, flutolanil, mepronil, and thiophanatemethyl significantly reduced the size of the first brood at concentrations less than half of those for LC50 (8 days)., Conclusions: In this study, chlornitrofen, pencycuron, and fenitrothion were suggested to have slow-acting toxicity. Also, thiobencarb, iprodione, flutolanil, mepronil, and thiophanatemethyl were suggested to have parthenogenetic toxicity.

Dimethylarsinous acid (DMAIII) induced tetraploidy and multinucleation in V79 cells. While the highest yield of tetraploids and multinucleated cells was at 1.25 microM of DMAIII, the mitotic index was highest at DMAIII 2.5 microM due to mitotic arrest. Mitosis was not observed at 5 microM. We observed V79 cells treated with DMAIII and visualized with rhodamine-phalloidin. Abnormal actin location was observed in the dividing cells which were treated with DMAIII and visualized with rhodamine-phalloidin. These findings suggested strongly that DMAIII inhibits not only formation of the normal mitotic spindle but cytokinesis and induces the formation of multinuclear cells.

Background: Arsenic in drinking water remains a major public problem in Bangladesh, although arsenic mitigation programs began there a decade ago. The purpose of this study was to examine the effectiveness of this program by determining the relationship between current arsenic levels in well water and the high level of urinary arsenic excretion., Methods: A community-based cross-sectional study was conducted in the Pabna district of Bangladesh between May and July 2005. We included 174 married couples and collected their drinking water from 138 wells. The allowable limit for arsenic in drinking water is 50 microg/L in Bangladesh, while the normal level of urinary arsenic is < or =40 microg x 1.5 L(-1) x day(-1) by Dhaka Community Hospital., Results: Of 348 subjects, 304 exceeded the urinary arsenic level of 40 microg x 1.5 L(-1) x day(-1). Of all wells, 44.2% had arsenic levels >50 microg/L. Multiple-adjusted odds ratios of urinary arsenic level >40 microg x 1.5 L(-1) x day(-1) were 8.90 (95% CI: 3.31-23.93) for the arsenic level in well water of 11-50 microg/L, and 53.07 (11.91-236.46) for that of 51-332 microg/L, compared with < or =10 microg/L. When the Bangladeshi standard arsenic level in drinking water of 50 microg/L was used, the sensitivity in detecting subjects with a urinary arsenic level >40 microg x 1.5 L(-1) x day(-1) was 50%, although when the World Health Organization (WHO) guideline value of 10 microg/L was used, it was 76.3%., Conclusions: Green marked wells, which the Bangladesh government regards as safe, are not always safe. The mitigation programs should use the WHO guideline arsenic level to determine the safety of well water for drinking.

Formaldehyde is a carcinogen to which humans are exposed daily, but few methods are available to quantify formaldehyde in biological samples. We developed a simple, sensitive and rapid technique for the quantification of formaldehyde in urine by derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine, using a headspace sampler coupled to a gas chromatograph equipped with an electron capture detector. The detection limit was 1.08 microg/L. The overall recovery of formaldehyde spiked in urine was 99%. The concentration of formaldehyde in urine obtained from healthy volunteers ranged from 56.85 to 144.57 microg/L. This method can be used successfully to measure formaldehyde in urine.

A total of 455 highly tetracycline-resistant Escherichia coli strains were isolated from 84 healthy swine from abattoirs and it was found that 56.9, 43.1, 22.2, 15.4, 2.6 and 1.5% of strains were resistant to chloramphenicol, ampicillin, kanamycin, trimethoprim-sulphamethoxazole, ofloxacin and gentamicin respectively. Interestingly, E. coli strains isolated from certain finisher hog groups exhibited resistance against 2-7 antimicrobials, but strains isolated from multiparous sow groups in each herd were resistant to only 2-4 antimicrobial agents. When randomly selected 108 tetracycline-resistant isolates were tested for the presence of resistance genes, the following genes tet(A) (n = 6), tet(B) (n = 95), tet(D) (n = 1) or both tet(A) and tet(B) (n = 6) were found to be distributed among them. Furthermore, 52 isolates carried the integrase 1 gene and 24 strains gave five different PCR amplicon profiles using primers from the variable region of integron. Extensive nucleotide sequence analyses of these amplicons revealed the presence of dhfrI, dhfrXII, dfr17, aadA, aadA2, aadA5, aadA21, aacA4 and catB3 genes which code for different antibacterial resistance proteins.

The carcinogenicity of monomethylarsonic acid (MMA(V)), a major metabolite of inorganic arsenics in human and experimental animals, was investigated in male Fischer 344 rats. A total of 129 rats at 10 weeks of age were randomly divided into three groups and received drinking water containing MMA(V) at doses of 0 (Control), 50, and 200 ppm ad libitum for 104 weeks. No significant differences were found between the control and the MMA(V)-treated groups regarding clinical signs, mortality, hematological, and serum biochemistry findings. Quantitative analysis of glutathione S-transferase placental form (GST-P) positive foci in liver revealed a significant increase of numbers and areas in the 200 ppm MMA(V)-treated group. In the urinary bladder MMA(V) induced simple hyperplasia and significantly elevated the proliferating cell nuclear antigen (PCNA)-positive index in the urothelium. A variety of tumors developed in rats of all groups, including the controls, but all were histologically similar to those known to occur spontaneously in F344 rats and there were no significant differences among the groups. Thus, it could be concluded that, under the present experimental conditions, MMA(V) induced lesions in the liver and urinary bladder, but did not cause tumor development in male F344 rats even after 2 years exposure.

Arsenic is a notorious environmental toxicant known to be carcinogenic for the skin, lung and urinary bladder in human beings. The carcinogenicity of trimethylarsine oxide (TMAO), one organic metabolite of inorganic arsenics in humans and experimental animals, was investigated here in male Fischer 344 rats in a 2-year carcinogenicity test. TMAO was administered to a total of 129 male rats ad libitum at concentrations of 0 (Control), 50 or 200 p.p.m. in the drinking water. In animals that died or were killed from the 87th week until the end of 104th week, incidences of hepatocellular adenomas were 14.3, 23.8 and 35.6% in the 0, 50 and 200 p.p.m.-treated groups, respectively; the multiplicities were 0.21, 0.33 and 0.53. Both were significantly increased in the 200 p.p.m.-treated group. While a variety of other tumors developed in various organs, they were present in all groups, including the controls, and were histologically diagnosed as those known to occur spontaneously in F344 rats. To test the contribution of reactive oxygen species (ROS) to TMAO tumorigenicity in the liver, 8-hydroxydeoxyguanosine (8-OHdG) formation was assessed by high performance liquid chromatography. The 8-OHdG values for the 200 p.p.m. TMAO group were significantly higher than those for the control group. Furthermore, as assessed by the proliferating cell nuclear antigen index, cell proliferation in the normally appearing parenchyma was elevated by the TMAO treatment. These results indicate that TMAO exerts liver tumorigenicity with possible mechanistic roles for oxidative DNA damage and enhanced cell proliferation.

There is abundant epidemiological evidence that arsenic is an environmental carcinogen related to human cancers of the skin, lung, liver and urinary bladder, in particular. Dimethylarsinic acid (DMA) has also been reported to act as a carcinogen/or a promoter in rat models. To elucidate molecular mechanisms, we conducted an 18 month carcinogenicity study of DMA in p53 heterozygous (+/-) knockout mice, which are susceptible to early spontaneous development of various types of tumors, and wild-type (+/+) C57BL/6J mice. Totals of 88-90 males, 7-8 weeks of age, were divided into three groups each administered 0, 50 or 200 p.p.m. DMA in their drinking water for 18 months. Mice that were found moribund or died before the end of the study were autopsied to evaluate the tumor induction levels, as well as those killed at the end. Both p53(+/-) knockout and wild-type mice demonstrated spontaneous tumor development, but lesions were more prevalent in the knockout case. Carcinogenic effect of DMA was evident by significant early induction of tumors in both treated p53(+/-) knockout and wild-type mice, significant increase of the tumor multiplicity in 200 p.p.m.-treated p53(+/-) knockout mice, and by significant increase in the incidence and multiplicity of tumors (malignant lymphomas) in the treated wild-type mice. By the end of 80 weeks, tumor induction, particularly malignant lymphomas and sarcomas, were similar in treated and control p53(+/-) knockout mice. No evidence for organ-tumor specificity of DMA was obtained. Molecular analysis using PCR-SSCP techniques revealed no p53 mutations in lymphomas from either p53(+/-) knockout or wild-type mice. In conclusion, DMA primarily exerted its carcinogenic effect on spontaneous development of tumors with both of the animal genotypes investigated here.

Arsenic is a well-documented human carcinogen, and contamination with this heavy metal is of global concern, presenting a major issue in environmental health. However, the mechanism by which arsenic induces cancer is unknown, in large part due to the lack of an appropriate animal model. In the present set of experiments, we focused on dimethylarsinic acid (DMA), a major metabolite of arsenic in most mammals including humans. We provide, for the first time, the full data, including detailed pathology, of the carcinogenicity of DMA in male F344 rats in a 2-year bioassay, along with the first assessment of the genetic alteration patterns in the induced rat urinary bladder tumors. Additionally, to test the hypothesis that reactive oxygen species (ROS) may play a role in DMA carcinogenesis, 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation in urinary bladder was examined. In experiment 1, a total of 144 male F344 rats at 10 weeks of age were randomly divided into four groups that received DMA at concentrations of 0, 12.5, 50 and 200 p.p.m. in the drinking water, respectively, for 104 weeks. From weeks 97-104, urinary bladder tumors were observed in 8 of 31 and 12 of 31 rats in groups treated with 50 and 200 p.p.m. DMA, respectively, and the preneoplastic lesion, papillary or nodular hyperplasias (PN hyperplasia), was noted in 12 and 14 rats, respectively. DMA treatment did not cause tumors in other organs and no urinary bladder tumors or preneoplastic lesions were evident in the 0 and 12.5 p.p.m.-treated groups. Urinary levels of arsenicals increased significantly in a dose-responsive manner except for arsenobetaine (AsBe). DMA and trimethylarsine oxide (TMAO) were the major compounds detected in the urine, with small amounts of monomethylarsonic acid (MMA) and tetramethylarsonium (TeMa) also detected. Significantly increased 5-bromo-2'-deoxyuridine (BrdU) labeling indices were observed in the morphologically normal epithelium of the groups treated with 50 and 200 p.p.m. DMA. Mutation analysis showed that DMA-induced rat urinary bladder tumors had a low rate of H-ras mutations (2 of 20, 10%). No alterations of the p53, K-ras or beta-catenin genes were detected. Only one TCC (6%) demonstrated nuclear accumulation of p53 protein by immunohistochemistry. In 16 of 18 (89%) of the TTCs and 3 of 4 (75%) of the papillomas, decreased p27(kip1) expression could be demonstrated. Cyclin D1 overexpression was observed in 26 of 47 (55%) PN hyperplasias, 3 of 4 (75%) papillomas, and 10 of 18 (56%) TCCs. As a molecular marker of oxidative stress, increased COX-2 expression was noted in 17 of 18 (94%) TCCs, 4 of 4 (100%) papillomas, and 39 of 47 (83%) PN hyperplasias. In experiment 2, 8-OHdG formation in urinary bladder was significantly increased after treatment with 200 p.p.m. DMA in the drinking water for 2 weeks compared with the controls. The studies demonstrated DMA to be a carcinogen for the rat urinary bladder and suggested that DMA exposure may be relevant to the carcinogenic risk of inorganic arsenic in humans. Diverse genetic alterations observed in DMA-induced urinary bladder tumors imply that multiple genes are involved in stages of DMA-induced tumor development. Furthermore, generation of ROS is likely to play an important role in the early stages of DMA carcinogenesis.