The Journal of Toxicological Sciences
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Volume 32 , Issue 2
May
Showing 1-11 articles out of 11 articles from the selected issue
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Original Article
  • Suleiman AMBALI, Dayo AKANBI, Noble IGBOKWE, Muftau SHITTU, Mohammed K ...
    Volume 32 (2007) Issue 2 Pages 111-120
    Released: May 31, 2007
    JOURNALS FREE ACCESS
    Chlorpyrifos (CPF) is one of the most widely used organophosphorous insecticides in agriculture with its attendant adverse health outcomes. This study aimed at evaluating the effect of subchronic oral CPF administration on hematological and serum biochemical indices, and the possible ameliorating effect of vitamin C on the indices in mice. Thirty mice divided into 3 groups of 10 mice each were used for this study. Mice in group I (control) were dosed with vegetable oil, while those in group II were given CPF (21.3 mg/kg~ 1/5th LD50) only. Mice in group III were pretreated with vitamin C (100 mg/kg) prior to dosing with CPF 30 min later (Vitamin C + CPF-treated group). This regime was given to each group of mice three times a week for a period of ten weeks. During the study period, mice were examined for signs of toxicity, and weight of each mouse was measured every week. At the end of the study period, blood samples were collected from the mice and analyzed for packed cell volume (PCV), total red blood cell (RBC), white blood cell (WBC) and total protein (TP). Serum obtained from the blood was analyzed for Na +, K+ and Cl−, urea, creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP). The results showed that mice in the vitamin C + CPF-treated group exhibited milder signs of toxicity and significant increase in weight gain (p<0.01) compared to the CPF-treated group. No significant increase in weight in the CPF-treated group was observed compared to the control. There was a significant increase in PCV, RBC, Hb, TP and creatinine, but a significant decrease was obtained in WBC, ALT and AST in the CPF-treated group compared to the control. All the parameters with the exception of WBC, ALT and AST (which increased significantly), were significantly decreased in the vitamin C + CPF-treated group compared to CPF-treated group. ALP was significantly elevated in the CPF-treated group compared to both the control and vitamin C + CPF-treated group. No significant changes in urea and the measured electrolytes in all three groups, except a significant decrease in the concentration of Na+ was observed in the CPF-treated group compared to the control. The study demonstrated that pretreatment of CPF-administered mice with vitamin C significantly altered some important hematological and serum biochemical parameters, revealing the protective action of the vitamin against some organ damage induced by CPF.
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  • Nobuhiro GOI, Yuuko HIRAI, Hitoshi HARADA, Akira IKARI, Takahiko ONO, ...
    Volume 32 (2007) Issue 2 Pages 121-127
    Released: May 31, 2007
    JOURNALS FREE ACCESS
    Saliva is the first body fluid to encounter exogenous materials or gases such as cigarette smoke (CS). The aim of this study was to examine whether smoking affects oral peroxidase (OPO) reactivity to mental stress. The subjects were 39 non-smokers and 10 smokers. In the experiment, the Kraepelin psychodiagnostic test as a psychological stressor and saliva was sampled 30 min before, just before, immediately after, and 30 min after the beginning of the test. OPO reactivity to the test between smokers and non-smokers was measured in addition to uric acid concentration, flow rate, IgA, thiocyanate (SCN−) concentration, amylase activity as a salivary stress marker, and ultra-weak chemiluminescence (UCL) level, which is indicative of salivary antioxidative and antibacterial abilities. Moreover, we studied the effect of smoking on the response of salivary peroxidase (SPO) and myeloperoxidase (MPO) activity to mental stress, respectively. The results showed that the IgA concentration, amylase activity, SCN− concentration, and UCL level are higher in the non-smoking group than smoking group and the IgA concentration and UCL level increased in the non-smokers significantly just after the Kraepelin test. The levels of SCN− were higher in smokers than in non-smokers and OPO activity was greater in the non-smoking group in all sessions. Furthermore, only the non-smokers had significantly increased MPO activity just after the test. MPO may play a crucial role in the response to acute psychological stress besides inflammation, and CS suppresses this response significantly.
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  • Kohji TANAKA, Naoki KIYOSAWA, Kyoko WATANABE, Sunao MANABE
    Volume 32 (2007) Issue 2 Pages 129-134
    Released: May 31, 2007
    JOURNALS FREE ACCESS
    In our previous study, we demonstrated that the initial hepatic injury caused by bromobenzene (BB) was no longer detected in rats despite subsequent dosing, indicating that the liver acquired resistance to BB-induced hepatotoxicity. In this experiment, microarray analysis was conducted to characterize this resistance. The liver samples for the analysis utilized were obtained from previous experiments where F344 rats were treated intraperitoneally with BB (150 mg/kg). At 24 hr post-dose, hepatic injury was confirmed by monitoring the AST values and then the rats were maintained at the same dosing regimen for an additional 8 days. The gene expression profiles of the BB-treated rat livers were compared with a vehicle-treated group by Affymetrix RG_U34A arrays. As results, a decreased expression level of CYP3A9 and an increased expression level of GST Yc2 and glutathione peroxidase (GPX) were detected. These changes indicated suppression of the phase I reaction and induction of the phase II reaction (glutathione conjugation). Increased expression levels of epoxide hydrolase (EH) and NAD(P)H:quinone oxidoreductase (NQO1) also suggested the involvement of EH- and NQO1-mediated hydrolysis other than glutathione conjugation with resistance in the phase II reaction. Moreover, an increased expression level of abcc3 (multidrug resistance protein 3; Mrp3) was significantly noted. Based on the present findings, it was suggested that Mrp3 in the phase III reaction (drug elimination) contributed to the resistance to BB hepatotoxicity in addition to the suppression of the phase I reaction (metabolic activation) and the induction of the phase II reaction (detoxification). Among them, the factors which contributed most were considered to be the increased GST Yc2 and Mrp3, based on the degree of the gene expression changes.
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  • Akikazu SAKUDO, Etsuro YOSHIMURA, Roumiana TSENKOVA, Kazuyoshi IKUTA, ...
    Volume 32 (2007) Issue 2 Pages 135-141
    Released: May 31, 2007
    JOURNALS FREE ACCESS
    A procedure has been used for the classification and quantification of metals on the basis of a chemometric analysis of visible and near-infrared (Vis-NIR) spectra of metals such as Cu, Mn and Fe in the brain, liver, kidney and testis of mice without digestion. Transmittance spectra in the 600- to 1000-nm region subjected to partial least-squares (PLS) regression analysis and leave-out cross-validation facilitated development of chemometrics models for predicting metal concentration. From the models, Cu, Mn and Fe yielded the coefficients of determination in cross-validation (R2VAL) as 0.8013, 0.9021 and 0.8295 with standard errors of cross-validation (SECV) of 3.399, 0.8237 and 76.512 μg per g tissue, respectively. The respective detection limits of Cu, Mn and Fe were 12.19, 2.616 and 266.32 μg per g tissue. Furthermore, the regression coefficients of the models showed specific patterns for the respective metals. These results suggest that Vis-NIR spectroscopy may have a great potential for analysis of native state of metals in tissues.
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  • Yoshitaka HIGA, Mayumi KAWABE, Kyoko NABAE, Yosuke TODA, Sachiko KITAM ...
    Volume 32 (2007) Issue 2 Pages 143-159
    Released: May 31, 2007
    JOURNALS FREE ACCESS
    Kojic acid (KA) has been widely used as a quasi-drug ingredient. Possible promotion activity of KA was suggested on livers of mouse and rat by findings obtained in genotoxicity and carcinogenicity studies performed thus far. Therefore, in order to examine safety as a quasi-drug ingredient, we investigated the presence of initiation activity in rat liver and the photo-genotoxicity and carcinogenicity in mouse skin. In medium-term carcinogenesis test in rats, 2.0% KA was orally given to F344/DuCrj rats for 4 weeks of the initiation period, followed by the combination of partial hepatectomy and treatment with a hepatocarcinogenesis promoter, phenobarbital (PB). As a result, glutathione S-transferase placental form (GST-P) positive foci of 0.2 mm or more in diameter in the KA group, which is usually used in determination of pre-cancerous lesions, did not increase significantly in both numbers and areas compared with those of the non-initiated controls. In the concurrent analysis, however, numbers of GST-P-positive foci of two cells or more and 0.1 mm or more in diameter increased slightly, and possible weak initiation activity of KA was equivocal. However, considering the known fact that KA exerts promotion activity in the liver of F344 rats by long-term dietary administration, it was suggested that the observed slight increase of the numbers of GST-P-positive foci in rat liver was the effect of promotion activity of KA rather than the initiation activity. In DNA adducts formation assay in a rat liver, no clear adducts derived from KA were detected in male F344/DuCrj rats administered 0.5% or 2% KA orally, and KA was considered not to form DNA adducts in rat liver. In the in vitro photo-reverse mutation assay with bacteria, KA exerted weak photo-mutagenicity. Furthermore, in chromosome aberration study in Chinese hamster lung cells (CHL/IU cells) with UV irradiation, KA induced chromosome aberration at high-dose (1.4 mg/mL) treatment with UV irradiation, but was negative without UV irradiation. However, in the in vivo photo-micronucleus study in mouse, in which 1.0 or 3.0% KA containing cream was applied twice to the back of the animals with a 24-hr interval, KA did not induce micronuclei in mouse epidermal cells. Based on these results, it is considered that the risk of KA to exert photo-carcinogenicity is quite low in the skin. In skin carcinogenesis bioassay for initiation-promotion potential, 3.0% KA cream formulation was applied to the back of the mouse for 1 week (once a day, total 7 times) and for 19 weeks (5 times a week, total 95 times) during the initiation and the promotion stages, respectively. No skin nodules were observed in any animal skins formed due to KA treatment given in either stage. Therefore, KA is considered not to possess initiation nor promotion activity of skin carcinogenesis. Furthermore, from the above findings, it is suggested that KA is virtually safe as a quasi-drug ingredient.
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  • MIYAZAKI, Satoko MIWA, Hirohiko KODAMA, Harutami YAMADA, Koichi NAGAT ...
    Volume 32 (2007) Issue 2 Pages 161-177
    Released: May 31, 2007
    JOURNALS FREE ACCESS
    In the present study, we investigated the potential toxic effects of 2-week oral treatment with T-0126, a novel microsomal triglyceride transfer protein (MTP) inhibitor, on the liver and intestine in male and female rats. Administration of T-0126 decreased serum lipids and resulted in fat accumulation in the liver and the small intestine. In addition, slight changes in the liver, including an increase in serum aminotransferase (AST and ALT) activity, presence of focal inflammatory lesions, and prolongation of PT and APTT were observed after treatment with T-0126. These changes may be related to a mechanism based on malabsorption of fat, fat-soluble antioxidants, and vitamin K, although we cannot exclude other potential mechanisms such as direct cytotoxicity of T-0126.
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Letter
  • Mariko IWASAKI, Itaru SATO, Yihe JIN, Norimitsu SAITO, Shuji TSUDA
    Volume 32 (2007) Issue 2 Pages 179-184
    Released: May 31, 2007
    JOURNALS FREE ACCESS
    The positive list system became effective from May 29, 2006 to improve the regulation of residual agricultural chemicals (pesticides, feed additives and veterinary drugs) in foods. In accordance with the system, we investigated pesticide residues in 50 agricultural products purchased in Morioka city from March to November 2006. Analyses were performed according to the "Multiresidue Method for Agricultural Chemicals by GC/MS", the Notice of the Ministry of Health, Labour and Welfare. Five pesticides and two non-agricultural chemicals were detected from 16 samples. Ortho-phenylphenol (OPP) was detected from 8 samples: immature pea, snap bean, kiwi, plain-boiled bamboo shoot, mango, white asparagus, lemon and domestic shiitake mushroom. Maximum residue limits (MRLs) have not been established for these products, and they exceeded the uniform level of 0.01 ppm. DDT was detected from Philippines banana (0.30 ppm) and Korean paprika (0.45 ppm). The residual level in Philippines banana was lower than the MRL, but Korean paprika exceeded its MRL. Chlorpyrifos, Thiabendazole and Imazaril were detected from citrus imported from the U.S.A., but their residue levels were lower than the respective MRLs. Aniline and 2-pyrrolidone were detected from several imported products. These two may not be regulated by the positive list system because they are not agricultural chemicals, although their derivatives are used as pesticides or veterinary drugs. Three problems have been revealed from this survey: 1) application of the uniform level to minor agricultural products, 2) residues of non-agricultural chemicals whose toxicity is uncertain, 3) metabolites of agricultural chemicals, which are also regulated by the positive list system, have not been clearly defined.
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  • Sadhana SHRIVASTAVA, Anjana JADON, Sangeeta SHUKLA
    Volume 32 (2007) Issue 2 Pages 185-192
    Released: May 31, 2007
    JOURNALS FREE ACCESS
    In the present study an attempt has been made to evaluate the effect of Tiron along with Zinc, Selenium and Vitamin E against vanadium intoxication in female albino rats. Toxicant caused significant increase in the activities of serum transaminases, serum alkaline phosphatase and lactate dehydrogenase. Significant decrease was observed in blood sugar, serum albumin and triglyceride levels whereas serum proteins, cholesterol and urea levels increased significantly during toxicity (p ≤ 0.001). Hepatic lipid peroxidation increased significantly, whereas significant depletion was observed in reduced glutathione after vanadium administration. The activity of glucose-6-phosphatase in the liver was also inhibited significantly after vanadium administration. A significant rise was observed in glycogen content of liver and kidney after toxicant exposure. Activities of alkaline phosphatase, adenosine triphosphatase and succinic dehydrogenase were inhibited significantly on the contrary activity of acid phosphatase elevated in kidney. Histopathological examination of the liver and kidney using light and ultramicroscopic study also substantiated the above findings. It was found that therapy with Tiron was effective but significant recovery in all the parameters was found with Tiron + Se followed by Tiron+ VitE and Tiron +Zn.
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  • Hirotomo YAMADA, Kaoru SUZUKI, Shinji KOIZUMI
    Volume 32 (2007) Issue 2 Pages 193-196
    Released: May 31, 2007
    JOURNALS FREE ACCESS
    Although Zn is an essential trace metal for humans, a comprehensive view of its effects on cellular functions has not been obtained. We used a DNA microarray to assess transcriptional alterations in human HeLa cells after exposure to a moderate concentration of Zn (100 μM ZnSO4). Out of 9,182 human genes, expression was increased in 7 genes and decreased in 4 genes twofold or greater. Four of the 7 upregulated genes were those coding for metallothionein isoforms or related proteins. An unexpectedly small extent of changes in gene expression might reflect rapid sequestration of Zn ions by metallothioneins, and the absence of most of the other protective responses indicated the non-toxic nature of Zn at this concentration. Comparison with our previous DNA microarray results for 5 μM CdSO4-exposed HeLa cells revealed several genes that are regulated by both metals in parallel, and a gene reciprocally regulated by them.
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  • Shobhana. G. NAYAK, Renuka SATISH, Gokulnath
    Volume 32 (2007) Issue 2 Pages 197-199
    Released: May 31, 2007
    JOURNALS FREE ACCESS
    Hemolytic uremic syndrome (HUS) has been associated with a variety of infective as well as non-infective causes. HUS as a toxic manifestation of exposure to herbicides/pesticides has not been reported so far in literature. We report a subject who presented with clinical features of features of HUS after intentional suicidal ingestion of the herbicidal agent monochloroacetic acid (MCA). A 55-year-old farmer was admitted with a history of consumption of monochloroacetic acid with vomiting, hematochezia and oligo-anuria. Our investigations revealed severe renal failure, metabolic acidosis, anemia, and thrombocytopenia with evidence of intravascular hemolysis. He was treated for HUS with plasma transfusions and haemodialysis in view of renal failure. During the course of hospital admission he developed acute antero-septal myocardial infarction and subsequently succumbed to the disease. MCA is used as an herbicidal agent and also a bleaching agent for silkworm cocoons. The toxicity of MCA has included metabolic acidosis, rhabdomyolysis and renal failure; however HUS has not been described in the literature. Extra −renal manifestations of HUS such as cardiomyopathy have also been infrequently described. This case is presented to highlight an as yet unknown toxicity of MCA.
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Toxicogenomics/proteomics Reports
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