内藤 久雄

BACKGROUND: People worldwide are routinely exposed to tellurium mainly via dietary ingestion. There has been no study to clarify the contribution of tellurium to blood pressure in humans or animals. METHODS: In this cross-sectional study conducted in a general population of 2592 residents in Japan, the associations of urinary tellurium levels with blood pressure and prevalence of hypertension were investigated. The potential sources of tellurium were also investigated. An interventional study in mice confirmed the effect of tellurium exposure on blood pressure. RESULTS: Linear and logistic regression analyses with consideration of confounders including urinary sodium-potassium ratio showed significant positive associations of urinary tellurium level with prevalence of hypertension and blood pressure. Cereals/beans and vegetables/fruits were determined to be potential dietary sources of tellurium exposure. Intermediary analysis suggested that increased intake of cereals/beans, but not that of vegetables/fruits, is positively associated with the tellurium-mediated risk of hypertension. Correspondingly, the mouse study showed that exposure to a putative human-equivalent dose of tellurium via drinking water increased blood pressure with an elevated level of urinary tellurium. The temporally increased blood pressure was decreased to the normal level by a break of tellurium exposure with a reduced level of urinary tellurium. CONCLUSIONS: The interdisciplinary approach provided the first evidence that tellurium exposure is a potential risk for increase of blood pressure. Since the human urinary tellurium level in this study is comparable with the levels in general populations in other Asian and European countries in previous studies, exposure to tellurium may be a latent universal risk for hypertension.

AIMS: There has been a shortage of human studies to elucidate the association between serum arsenic levels and the prevalence of hypertension. This study multidirectionally investigated associations among arsenic exposure, dietary ingestion, and the risk of hypertension by combined human epidemiological and mouse experimental studies. METHODS AND RESULTS: This study focused on the total arsenic level in fasting serum, a biomarker of arsenic exposure. Associations among ingestion frequencies of 54 diet items of Japanese food separated into six categories, total arsenic level in fasting serum, and the prevalence of hypertension were investigated in 2709 general people in Japan. Logistic regression analysis demonstrated a dose-dependent association between serum arsenic level and hypertension and a positive association between the ingestion of fish meat and hypertension. Further analysis showed that the latter association was fully mediated by increased fasting serum arsenic levels in humans. Similarly, oral exposure to the putative human-equivalent dose of arsenic species mixture with the same ratios in a common fish meat in Japan increased systolic blood pressure and arsenic levels in fasting serum in mice. CONCLUSION: This interdisciplinary approach suggests that fish-meat ingestion is a potential risk factor for arsenic-mediated hypertension. Because the increased consumption of fish meat is a recent global trend, health risks of the increased ingestion of arsenic via fish meat should be further investigated.

Occupational exposure to trichloroethylene (TCE) causes a systemic skin disorder with hepatitis known as TCE hypersensitivity syndrome (TCE-HS). Human Leukocyte Antigen (HLA)-B*13:01 is its susceptibility factor; however, the immunological pathogenesis of TCE-HS remains unknown. We herein examined the hypothesis that autoantibodies to CYP2E1 are primarily involved in TCE-HS. A case-control study of 80 TCE-HS patients, 186 TCE-tolerant controls (TCE-TC), and 71 TCE-nonexposed controls (TCE-nonEC) was conducted to measure their serum anti-CYP2E1 antibody (IgG) levels. The effects of TCE exposure indices, such as 8-h time-weighted-average (TWA) airborne concentrations, urinary metabolite concentrations, and TCE usage duration; sex; smoking and drinking habits; and alanine aminotransferase (ALT) levels on the antibody levels were also analyzed in the two control groups. There were significant differences in anti-CYP2E1 antibody levels among the three groups: TCE-TC > TCE-HS patients > TCE-nonEC. Antibody levels were not different between HLA-B*13:01 carriers and noncarriers in TCE-HS patients and TCE-TC. The serum CYP2E1 measurement suggested increased immunocomplex levels only in patients with TCE-HS. Multiple regression analysis for the two control groups showed that the antibody levels were significantly higher by the TCE exposure. Women had higher antibody levels than men; however, smoking, drinking, and ALT levels did not affect the anti-CYP2E1 antibody levels. Anti-CYP2E1 antibodies were elevated at concentrations lower than the TWA concentration of 2.5 ppm for TCE exposure. Since HLA-B*13:01 polymorphism was not involved in the autoantibody levels, the possible mechanism underlying the pathogenesis of TCE-HS is that TCE exposure induces anti-CYP2E1 autoantibody production, and HLA-B*13:01 is involved in the development of TCE-HS.

Abstract Despite identification of arsenic intake from well drinking water in developing countries as a crucial hazard for health, the health effects of diet-mediated intake of arsenic on health in developed countries have remained unclear. The Japanese diet, which is regarded as a healthy diet, includes a high intake of seafoods that contain high levels of arsenic. The associations among intake of Japanese food including 54 food items classified into 6 categories, arsenic exposure and hypertension were investigated in 2,709 adults in Japan. Logistic regression analysis including serum sodium and potassium levels as confounders indicated a positive association between fasting serum level of arsenic (fsl-As) and prevalence of hypertension. Seaweed, bone-edible small fish and fish meat in seafoods were strong contributors to the increased fsl-As among the food items examined. Fish meat intake was identified as the greatest contributor to prevalence of hypertension. Since 94% of arsenic has been reported to be caused by dietary intake in Japan, our results suggest that increased fsl-As caused by intake of fish meat could be a potential risk for hypertension. Considering the worldwide trend of increased fish meat intake, arsenic in fish meat might be a new global hazardous material.

BACKGROUND: There is limited evidence regarding the relationship between Diabetes mellitus (DM) in middle age and mild cognitive impairment after a follow-up. Therefore, we investigated the relationship between fasting blood glucose (FBG) levels in middle age and cognitive function (assessed using the Japanese version of the Montreal Cognitive Assessment (MoCA-J) in later life, following over 15 years of follow-up in the Aichi Workers' Cohort Study in Japan. METHODS: Participants were 253 former local government employees aged 60-79 years in 2018 who participated in a baseline survey conducted in 2002. Using baseline FBG levels and self-reported history, participants were classified into the normal, impaired fasting glucose (IFG) and, and DM groups. Total MoCA-J score ranges from 0 to 30, and cognitive impairment was defined as MoCA-J score ≤25 in this study. A general linear model was used to estimate the mean MoCA-J scores in the FBG groups, adjusted for age, sex, educational year, smoking status, alcohol consumption, physical activity, body mass index, systolic blood pressure, total cholesterol, and estimated glomerular filtration rate. RESULTS: The mean MoCA-J score in the total population was 25.0, and the prevalence of MoCA-J score ≤25 was 49.0%. Multivariable-adjusted total MoCA-J scores were 25.2, 24.8, and 23.4 in the normal, IFG, and DM groups, respectively. The odds ratio of MoCA-J score ≤25 in the DM group was 3.29. CONCLUSIONS: FBG level in middle age was negatively associated with total MoCA-J scores assessed later in life, independent of confounding variables.

We developed a highly sensitive method for quantifying 21 bile acids (BAs) in the rat liver by capillary liquid chromatography tandem mass spectrometry (cLC/MS/MS) with one-pot extraction. High recovery rates were obtained for the one-pot methods with either methanol (MeOH) extraction or MeOH/acetonitrile (ACN) (1:1, v/v) mixture extraction; the results obtained for the MeOH/ACN mixture solution were better than the results obtained for MeOH. Thus, we determined that the one-pot method with MeOH/ACN was the most suitable method for the efficient extraction of BAs in the liver. Targeted BAs were well separated by cLC with gradient elution using ammonium acetate (NH4OAc)-MeOH mobile phases. Method validation proved that the intra-day and inter-day accuracies and precisions were primarily less than ±20 and 20% relative standard deviation, respectively. Also, the limit of detection (LOD) and the limit of quantitation (LOQ) were 0.9-10 and 2.3-27 ng/g liver, which proves the high sensitivity of the method. Finally, we quantitated 21 BA concentrations in the liver samples of normal and nonalcoholic steatohepatitis (NASH) rats, both of which were derived from stroke-prone spontaneously hypertensive five (SHRSP5) /Dmcr rat. The hepatic BA profiles were found to be substantially different between the normal and NASH groups; the two groups were clearly separated along the first component axis in the score plots of the principal component analysis. In particular, 10 BAs (β-muricholic acid (MCA), glyco (G-) cholic acid (CA), G-chenodeoxycholic acid (CDCA), tauro (T-) CA, T-CDCA, T-ursodeoxycholic acid (UDCA), T-lithocholic acid (LCA), T-hiodeoxycholic acid (HDCA), T-α-MCA, and T-β-MCA) were significantly different between the two groups using Welch's t-test with the false discovery rate correction method, demonstrating BA disruption in the NASH model rat. In conclusion, this method was able to quantify 21 BAs in the rat liver and will evaluate the hepatic BA pathophysiology of rat disease models.

Hypertension is an important risk factor for nonalcoholic steatohepatitis. We have previously demonstrated that hypertensive rats fed a high fat and cholesterol (HFC) diet incurred a more severe hepatic inflammatory response and fibrosis. Here we investigated the role of hypertension in NASH by comparing HFC-induced hepatic fibrogenesis between spontaneously hypertensive rats (SHRs) and their normotensive Wistar Kyoto counterpart. Compared to the counterpart, the HFC diet led to stronger aggregation of CD68-positive macrophages in SHRs. HFC feeding also resulted in significantly higher upregulation of the fibrosis-related gene alpha-smooth muscle actin in SHR. The HFC diet induced higher overexpression of serum tissue inhibitor of metalloproteinase-1 (TIMP1) and greater suppression of matrix metalloproteinase-2 (MMP2):TIMP1, MMP8:TIMP1, and MMP9:TIMP1 ratios, as a proxy of the activities of these MMPs in SHR. Administration of the antihypertensive agent hydralazine to SHRs significantly ameliorated HFC-induced liver fibrosis; it suppressed the aggregation of CD68-positive macrophages and the upregulation of platelet-derived growth factor receptor beta, and collagen, type 1, alpha-1 chain. In conclusion, a hypertensive environment exacerbated the hepatic fibrogenetic effects of the HFC diet; while the effects were partially reversed by the antihypertensive agent hydralazine. Our data suggest that antihypertensive drugs hold promise for treating NASH exacerbated by hypertension.

We examined the association between objective and perceived neighborhood characteristics and self-reported leisure-time physical activity (PA) in older Japanese residents living in areas ranging from metropolitan to rural in 2016. Objective measures used were walkability and the numbers of parks/green spaces and sports facilities within 500 or 1000 m of subjects' homes, calculated using geographic information systems. Subjective measures were the subjects' perceptions of their neighborhoods, assessed using a structured questionnaire. All variables were divided into three groups, and the lowest tertile was used as the reference. We assessed the location and frequency of strolling or brisk walking, moderate-intensity PA, and vigorous-intensity PA (sports) using a self-reported questionnaire and defined as performing a certain type of PA 3-4 times/week as a habit. Living in a neighborhood in the highest tertile for walkability and number of parks/green spaces as well as perception of having good access to recreational facilities, observing others exercising and the presence of walkable sidewalks was associated with walking and sports habits (multivariable odds ratios (ORs): 1.33-2.46, all p < 0.05). Interestingly, objective measures of PA-friendly environmental features were inversely associated with moderate-intensity PA habits, potentially because moderate-intensity PA consisted predominantly of gardening. In conclusion, living in an environment supportive of PA, whether objectively or subjectively measured, is related to leisure-time PA habits among older Japanese adults.

Occupational trichloroethylene (TCE) exposure can cause hypersensitivity syndrome (TCE-HS). The human leukocyte antigen (HLA)-B*13:01 is reportedly an important allele involved in TCE-HS onset. However, the threshold exposure level causing TCE-HS in relation to HLA-B*13:01 remains unknown. We conducted a case-control study comprising 37 TCE-HS patients and 97 age- and sex-matched TCE-tolerant controls from the Han Chinese population. Urine and blood of patients were collected on the first day of hospitalization, and those of controls were collected at the end of their shifts. Urinary trichloroacetic acid (TCA) was measured as an exposure marker, and end-of-shift levels in the patients were estimated using the biological half-life of 83.7 h. HLA-B genotype was identified using DNA from blood. Crude odds ratios (ORs) for TCE-HS in the groups with urinary TCA concentration >15 mg/L to ≤50 mg/L and of >50 mg/L were 21.9 [95% confidence interval (CI) 4.2-114.1] and 27.6 (6.1-125.8), respectively, when the group with urinary TCA ≤15 mg/L was used as a reference. The frequency of HLA-B*13:01, the most common allele in the patients, was 62.2% (23/37), which was significantly higher than 17.5% (17/97) in the TCE-tolerant controls, with a crude OR of 8.4 (3.1-22.6). The mutually-adjusted ORs for urinary TCA >15 to ≤50 mg/L, >50 mg/L, and for HLA-B*13:01 were 33.4 (4.1-270.8), 34.0 (5.3-217.1), and 11.0 (2.4-50.7), respectively. In conclusion, reduction of TCE exposure to ≤15 mg/L is required for TCE-HS prevention because urinary TCA concentration >15 mg/L showed increased risk of TCE-HS, regardless of whether the patients had the HLA-B*13:01 allele.

OBJECTIVES: Occupational exposure to trichloroethylene (TCE) induces trichloroethylene hypersensitivity syndrome (TCEHS), which causes hypersensitivity dermatitis and hepatitis. However, whether TCE itself or its two metabolites, trichloroethanol (TCEOH) and trichloroacetic acid (TCA), are involved in TCEHS remains unclear. Therefore, in this study we explored the allergens causing TCEHS and characterized TCEHS-related liver injury in guinea pigs. METHOD: The guinea pig maximization test was performed using TCE, TCEOH, and TCA as candidate allergens. Skin inflammation was scored, and liver function and histopathological changes were evaluated by biochemical tests and hematoxylin and eosin staining, respectively. RESULTS: The sensitization rates for TCE, TCEOH, and TCA were 90.0%, 50.0%, and 0.0%, respectively. In the TCE and TCEOH experimental groups, the skin showed varying degrees of erythema with eosinophil granulocyte infiltration in the dermis. Additionally, serum alanine aminotransferase and γ-glutamyl transpeptidase levels increased significantly, and histological analysis revealed focal hepatocellular necrosis with inflammatory cell infiltration in the liver. CONCLUSIONS: TCE is the main cause of allergy and TCEOH is a secondary factor for allergy in guinea pigs. TCE and TCEOH can cause immune-mediated skin sensitization complicated by focal hepatic necrosis.

Exposure of pregnant mice to di(2-ethylhexyl)phthalate (DEHP) induces maternal lipid malnutrition and decreases the number of live fetuses/pups. In this study, we aimed to clarify the relationship between maternal lipid malnutrition and the nutritional status of the neonatal, lactational, and adult offspring, as well as the role of peroxisome proliferator-activated receptor α (PPARα) in these relationships. Sv/129 wild-type (mPPARA), Ppara-null, and PPARα-humanized (hPPARA) mice were fed diets containing 0, 0.01, 0.05, or 0.1% DEHP in utero and/or during the lactational stage. The male offspring were killed on postnatal day 2 or 21, or after 11 weeks. Exposure to either 0.05% or 0.1% DEHP during both the in utero and lactational periods decreased serum glucose concentrations in 2-day-old mPPARA offspring. These dosages also decreased both serum and plasma leptin levels in both 2- and 21-day-old mPPARA offspring. In contrast, exposure to DEHP only during the lactational period did not decrease leptin levels, suggesting the importance of in utero exposure to DEHP. Exposure to 0.05% DEHP during the in utero and lactational periods also increased food consumption after weaning in both mPPARA and hPPARA mice; this was not observed in Ppara-null offspring. In conclusion, in utero exposure to DEHP induces neonatal serum glucose malnutrition via PPARα. DEHP also decreases serum and plasma leptin concentrations in offspring during the neonatal and weaning periods, in association with PPARα, which presumably results in increased of food consumption after weaning.

Objective: An association between smoking and nonalcoholic fatty liver disease has been reported. However, objective quantification of intrahepatic fat via magnetic resonance spectroscopy (MRS) in relation to smoking has rarely been performed in previous studies. Moreover, the possible pathways via which smoking could induce ectopic fat accumulation have not yet been addressed. The current study aimed to examine the association between smoking status and intrahepatic fat quantity and explore the possible mediating effects of triglycerides (TG) and adiponectin. Subjects and methods: Magnetic resonance imager (MRI) spectra were analyzed to quantify intrahepatic fat in 45 men who were on average 62.3 years of age. Smoking status and alcohol intake were self-reported. Accelerometers were used to record daily total physical activity. Fasting blood TG and adiponectin levels were measured enzymatically. Differences in mean intrahepatic fat values according to smoking status were assessed using analysis of covariance. Results: A stepwise increase in mean intrahepatic fat was observed between never, former, and current smokers, respectively, independent of age, physical activity, alcohol intake, and body mass index (BMI) (P=0.005). Adjustment for TG and adiponectin significantly attenuated this association (P=0.074). Conclusion: Current smoking was significantly associated with increased intrahepatic fat, which may be a result of adipocyte dysfunction, manifested as high circulating TG concentrations and low adiponectin levels.

Purpose: 1,2-Dichloropropane(DCP) is thought to induce cholangiocarcinoma(CCA) among Japanese printing workers in 2013. However no studies have shown DCP-induced CCA in rodents. Five kinds of rodents were exposed to DCP to find an appropriate animal model for DCP-induced CCA.<br>Methods: First, 12 C57BL/6J mice, Balb/cA mice, F344 rats, Syrian Hamsters and Guinea Pigs were divided into 4 groups equally and exposed to DCP at 0, 300, 1000 and 3000 ppm respectively. Then 32 Balb/cA mice and Syrian Hamsters were divvied into 4 groups equally and exposed to DCP at 0, 200, 400 and 800ppm respectively. After the last exposure livers were dissected out for immunohistochemistry with anti- GSTT1, GSTM1, GSTPi antibodies.<br>Result: Either in control or exposed group all of the animals expressed GSTT1 both at liver cells and bile duct cells. <br>Conclusion: GSTT1 expression cannot explain the gap between human and rodents in the case of DCP inducing CCA.

OBJECTIVES: It has been reported that 1,2-Dichloropropane (DCP) induced cholangiocarcinoma (CCA) in offset color proof-printing workers. However, exposure to DCP by inhalation or gavage for 2 year did not induce CCA in mice and rats. The present study mapped the hepatic distribution of GST, which is known to activate dihalogenated alkanes, and proliferative and fibrotic changes in bile ducts in various species to find the most appropriate animal model of DCP-induced CCA. METHODS: First, 12 each of C57BL/6J mice, Balb/cA mice, F344 rats, Syrian hamsters, and guinea pigs were divided into four equal groups and exposed to DCP at 0, 300, 1,000, or 3,000 ppm 8 hours/day for 7 days. Second, 32 Balb/cA mice and 32 Syrian hamsters were each divided into four equal groups and exposed to DCP at 0, 200, 400, and 800 ppm 6 hours/day for 14 days. After the last exposure, the animals were decapitated, and the livers were dissected out for histopathological evaluation. Immunostaining was conducted to determine the distribution of GSTT1, GSTM1, and GSTPi, as well as the expression of proliferation marker Ki67. RESULTS: GSTT1, GSTM1, and GSTPi were expressed in both hepatocytes and bile duct cells in all control and exposed animals. There was no clear difference in the expression of Ki67 between the exposed groups and the control. No fibrotic changes were observed in any species or strains examined. CONCLUSIONS: Expression of GSTT1 or other GST isozymes might not explain the difference in sensitivity of hepatocytes and the bile duct to DCP between humans and rodents.

PURPOSE: 1-Bromopropane (1-BP) intoxication is associated with depression and cognitive and memory deficits. The present study tested the hypothesis that 1-BP suppresses neurogenesis in the dentate gyrus, which is involved in higher cerebral function, in adult rats. METHODS: Four groups of 12 male Wistar rats were exposed to 0, 400, 800, 1000 ppm 1-BP, 8 h/day for 7 days. Another four groups of six rats each were exposed to 0, 400, 800 and 1000 ppm 1-BP for 2 weeks followed by 0, 200, 400 and 800 ppm for another 2 weeks, respectively. Another four groups of six rats each were exposed to 0, 200, 400 and 800 ppm 1-BP for 4 weeks. Rats were injected with 5-bromo-2'-deoxy-uridine (BrdU) after 4-week exposure at 1000/800 ppm to examine neurogenesis in the dentate gyrus by immunostaining. We measured factors known to affect neurogenesis, including monoamine levels, and mRNA expression levels of brain-derived neurotrophic factor (BDNF) and glucocorticoid receptor (GR), in different brain regions. RESULTS: BrdU-positive cells were significantly lower in the 800/1000 ppm-4-week group than the control. 1-Week exposure to 1-BP at 800 and 1000 ppm significantly reduced noradrenalin level in the striatum. Four-week exposure at 800 ppm significantly decreased noradrenalin levels in the hippocampus, prefrontal cortex and striatum. 1-BP also reduced hippocampal BDNF and GR mRNA levels. CONCLUSION: Long-term exposure to 1-BP decreased neurogenesis in the dentate gyrus. Downregulation of BDNF and GR mRNA expression and low hippocampal norepinephrine levels might contribute, at least in part, to the reduced neurogenesis.