It is known that genotoxic N-nitroso carcinogens induce DNA damage in mouse liver within a few hours and induce mutations within 28 days after their administration. However, related-gene expression ...changes at these time points in liver were not fully elucidated. Differential gene expression induced by two genotoxic N-nitroso carcinogens in mouse liver was examined 4 h and 28 days after their administration with in-house oligonucleotide microarray (268 genes) and quantitative real-time PCR, and compared to that of a non-genotoxic carcinogen and a non-carcinogenic toxin. Diethylnitrosamine (DEN, 80 mg/kg bw), dipropylnitrosamine (DPN, 250 mg/kg bw), phenobarbital sodium (30 mg/kg bw) and ethanol (1000 mg/kg bw) were injected intraperitoneally into groups of male 9-week-old B6C3F1 mice and liver was dissected after 4 h and 28 days. mRNA from pooled livers was reverse-transcribed to cDNA, and Cy3- and Cy5-labeled cDNA was competitively hybridized with in-house made microarray, scanned and analyzed; additionally, quantitative real-time PCR was performed for selected genes. Differential gene expression between two genotoxic N-nitroso carcinogens and phenobarbital and ethanol was observed in 11 genes 4 h after administration, including seven tumor suppressor p53 target genes, viz. c-Jun, Ccng1, Mdm2, p21, Bax, Hsp27 and Snk; the other genes were Mbd1, Hmox-1, Ccnf and Rad52. However, only some degree of differential gene expression of p21, Ccng1 and Snk was observed 28 days after administration; no other differentially-expressed genes were evident. The present results suggest that DEN and DPN induce differential gene expression in p53 target genes in liver within a few hours after administration and that these acute responses remained only partially in liver after 28 days.
The Non-genotoxic Carcinogen Study Group in the Environmental Mutagen Society of Japan organised the second step of the inter-laboratory collaborative study on one-stage and two-stage cell ...transformation assays employing BALB/c 3T3 cells, with the objective of confirming whether the respective laboratories could independently produce results relevant to initiation or promotion. The method was modified to use a medium consisting of DMEM/F12 supplemented with 2% fetal bovine serum and a mixture of insulin, transferrin, ethanolamine and sodium selenite, at the stationary phase of cell growth. Seventeen laboratories collaborated in this study, and each chemical was tested by three to five laboratories. Comparison between the one-stage and two-stage assays revealed that the latter method would be beneficial in the screening of chemicals. In the test for initiating activity with the two-stage assay (post-treated with 0.1μg/ml 12-O-tetradecanoylphorbol-13-acetate), the relevant test laboratories all obtained positive results for benzoapyrene and methylmethane sulphonate, and negative results for phenanthrene. Of those laboratories assigned phenacetin for the initiation phase, two returned positive results and two returned negative results, where the latter laboratories tested up to one dose lower than the maximum dose used by the former laboratories. In the exploration of promoting activity with the twostage assay (pretreated with 0.2μg/ml 3-methylcholanthrene), the relevant test laboratories obtained positive results for mezerein, sodium orthovanadate and TGF-β1, and negative results for anthralin, phenacetin and phorbol. Two results returned for phorbol 12,13-didecanoate were positive, but one result was negative — again, the maximum dose to achieve the latter result was lower than that which produced the former results. These results suggest that this modified assay method is relevant, reproducible and transferable, provided that dosing issues, such as the determination of the maximum dose, are adequately considered. The application of this two-stage assay for screening the initiating and promoting potential of chemicals is recommended for consideration by other research groups and regulatory authorities.
It is known that genotoxic N-nitroso carcinogens induce DNA damage in mouse liver within a few hours and induce mutations within 28 days after their administration. However, related-gene expression ...changes at these time points in liver were not fully elucidated. Differential gene expression induced by two genotoxic N-nitroso carcinogens in mouse liver was examined 4 h and 28 days after their administration with in-house oligonucleotide microarray (268 genes) and quantitative real-time PCR, and compared to that of a non-genotoxic carcinogen and a non-carcinogenic toxin. Diethylnitrosamine (DEN, 80 mg/kg bw), dipropylnitrosamine (DPN; 250 mg/kg bw), phenobarbital sodium (30 mg/kg bw) and ethanol (1000 mg/kg bw) were injected intraperitoneally into groups of male 9-week-old B6C3F1 mice and liver was dissected after 4 h and 28 days. mRNA from pooled livers was reverse-transcribed to cDNA, and Cy3- and Cy5-labeled cDNA was competitively hybridized with in-house made microarray, scanned and analyzed; additionally, quantitative real-time PCR was performed for selected genes. Differential gene expression between two genotoxic N-nitroso carcinogens and phenobarbital and ethanol was observed in 11 genes 4 h after administration, including seven tumor suppressor p53 target genes, viz. c-Jun, Ccng1, Mdm2, p21, Bax, Hsp27 and Snk; the other genes were Mbd1, Hmox-1, Ccnf and Rad52. However, only some degree of differential gene expression of p21, Ccng 1 and Snk was observed 28 days after administration; no other differentially-expressed genes were evident. The present results suggest that DEN and DPN induce differential gene expression in p53 target genes in liver within a few hours after administration and that these acute responses remained only partially in liver after 28 days.
The Non-genotoxic Carcinogen Study Group of the Environmental Mutagen Society of Japan organised the first step of an interlaboratory validation study on an improved cell transformation assay ...employing Balb/c 3T3 A31-1-1 cells. Nineteen laboratories participated in this study. The modified transformation assay was evaluated for its responsiveness, its inter-laboratory reproducibility and its transferability. In this study, a mixture of Dulbecco's modified Eagle's medium and nutrient mixture F12, supplemented with insulin-transferrin-ethanolamine-sodium selenite and 2% fetal bovine serum (FBS) was used during the period of expression of transformed foci, instead of the usual minimum essential medium with 10% FBS. 20-Methylcholanthrene (MCA) and 12-O-tetradecanoylphorbol-13-acetate (TPA) were selected as a prototype initiator and a tumour promoter, respectively. Two series of experiments were conducted. In the first series, the transformation activity of MCA was examined at various concentrations. In the absence of the promoting treatment with TPA, exposure to MCA only weakly induced transformed foci. In the presence of 0.1 micrograms/ml TPA, all laboratories observed significant dose-dependent increases in the number of transformed foci with increasing MCA concentrations. In the second series of experiments, various concentrations of TPA were tested. In the absence of initiating treatment with MCA, exposure to TPA weakly induced transformed foci in about half of the laboratories. In the presence of 0.2 micrograms/ml MCA, all the laboratories observed significant dose-dependent increases in the number of transformed foci with increasing TPA concentrations. The results from this study support the usefulness of this modified two-stage transformation assay with Balb/c 3T3 cells.
Objective The prognosis of patients with protein-energy malnutrition seems to be affected by electrolyte abnormalities as well as poor nutritional status. Consequently, we hypothesize that one of the ...beneficial effects of nutrition support is improvement of electrolyte abnormalities in patients with malnutrition. In order to examine the hypothesis, a clinical study on the relationship between nutritional support and electrolyte abnormalities was performed. Methods Three hundred and fifteen patients to whom we performed nutrition support from August, 2006 to May, 2009 were enrolled in the present study. Based on estimated energy expenditure calculated in Harris Benedict equations, these patients were divided into following two groups: adequate nutrient intake group (adequate group) and inadequate nutrient intake group (inadequate group). Nutritional status, renal function and electrolyte abnormalities were analyzed and compared between initial and final points of nutrition support team intervention in each group. Results Renal function was comparable between initial and final points in both adequate group and inadequate group. In contrast, nutritional status was improved only in adequate group. Concerning electrolyte abnormalities, sodium and phosphorus seem to be closely related to nutrition therapy. Conclusion Nutrition support is useful for improvement of electrolyte abnormalities, especially in sodium and phosphorus, as well as nutritional status improvement.
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