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91.
Aki Nakayama Shougo Koyoshi Shinsuke Morisawa Takashi Yagi 《Mutation Research - Genetic Toxicology and Environmental Mutagenesis》2000,470(2):975
Benzene is one of the chemicals widely contaminating the environment. Benzene is suggested to be a human leukemogen. When benzene is absorbed in the human body, it is metabolized firstly in the liver and subsequently in the bone marrow where it provokes initiation of leukemia. In the present study, we analyzed mutations induced by p-benzoquinone (p-BQ), a benzene metabolite, in human cells using a shuttle vector plasmid pMY189, and compared frequencies, types and spectra of the mutations with those of the mutations previously revealed in mouse cells using a similar plasmid pNY200. We found that p-BQ induces mutations in human and mouse cells at similar frequencies but with different types of mutagenesis. The proportion of tandem base mutations was significantly lower in human cells than in mouse cells. Most base substitutions were induced in G:C base pairs in both human and mouse cells. However, the proportion of G:C→C :G transversion is significantly higher in human cells. These findings indicate that the p-BQ-induced DNA damage in human and mouse cells is processed in a different manner, and that extrapolation of mice findings on experimental benzene carcinogenesis to human cancer risk assessment should be conducted carefully. 相似文献
92.
Makiko Oboshi Yoshiro Naito Hisashi Sawada Shinichi Hirotani Toshihiro Iwasaku Yoshitaka Okuhara Daisuke Morisawa Akiyo Eguchi Koichi Nishimura Kenichi Fujii Toshiaki Mano Masaharu Ishihara Tohru Masuyama 《PloS one》2015,10(5)
BackgroundDeep vein thrombosis (DVT) is a major cause of pulmonary thromboembolism and sudden death. Thus, it is important to consider the pathophysiology of DVT. Recently, iron has been reported to be associated with thrombotic diseases. Hence, in this study, we investigate the effects of dietary iron restriction on the process of thrombus resolution in a rat model of DVT.MethodsWe induced DVT in 8-week-old male Sprague-Dawley rats by performing ligations of their inferior venae cavae. The rats were then given either a normal diet (DVT group) or an iron-restricted diet (DVT+IR group). Thrombosed inferior venae cavae were harvested at 5 days after ligation.ResultsThe iron-restricted diet reduced venous thrombus size compared to the normal diet. Intrathrombotic collagen content was diminished in the DVT+IR group compared to the DVT group. In addition, intrathrombotic gene expression and the activity of matrix metalloproteinase-9 were increased in the DVT+IR group compared to the DVT group. Furthermore, the DVT+IR group had greater intrathrombotic neovascularization as well as higher gene expression levels of urokinase-type plasminogen activator and tissue-type plasminogen activator than the DVT group. The iron-restricted diet decreased intrathrombotic superoxide production compared to the normal diet.ConclusionsThese results suggest that dietary iron restriction affects the process of thrombus resolution in DVT. 相似文献
93.
Keiko Mitsunaga-Nakatsubo Miyuki Kanda Ken Yamazaki Hiroto Kawashita Akiko Fujiwara Kazumi Yamada Koji Akasaka Hiraku Shimada Ikuo Yasumasu 《Development, growth & differentiation》1992,34(6):677-684
A marked increase in the Na+ , K+ -ATPase activity of sea urchin embryos occurred following an elevation of its mRNA level, revealed by Northern blotting analysis, in developmental period between the swimming blastula and the late gastrula stage. cDNA clone of Na+ , K+ -ATPase α-subunit, obtained from γgt10 cDNA library of sea urchin gastrulae, was digested with EcoRl ad Hindlll. The obtained 268 bp cDNA fragment, hybridized to a 4.6 Kb RNA, was used as probe for Northern blotting analysis. The level of Na+ , K+ -ATPase mRNA was higher in embryo-wall cell fraction isolated from late gastrulae (ectoderm cells) than the level in the bag fraction, containing mesenchyme cells (mesoderm cells) and archenteron (endoderm cells). The activity of Na+ , K+ -ATPase and the level of its mRNA were higher in animalized embryos obtained by pulse treatment with A23187 for 3 hr, starting at the 8–16 cell stage and were considerably lower in vegetalized embryos induced by 3 hr treatment with Li+ than that in normal embryos at the post gastrula corresponidng stage. Augmentation of Na+ , K+ -ATPase gene expression can be regarded as a marker for ectoderm cell differentiation at the post gastrula stage, which results from determination of cell fate in prehatching period. 相似文献
94.
Sakoda H Ogihara T Anai M Fujishiro M Ono H Onishi Y Katagiri H Abe M Fukushima Y Shojima N Inukai K Kikuchi M Oka Y Asano T 《American journal of physiology. Endocrinology and metabolism》2002,282(6):E1239-E1244
5-Aminoimidazole-4-carboxamide ribonucleoside (AICAR) reportedly activates AMP-activated protein kinase (AMPK) and stimulates glucose uptake by skeletal muscle cells. In this study, we investigated the role of AMPK in AICAR-induced glucose uptake by 3T3-L1 adipocytes and rat soleus muscle cells by overexpressing wild-type and dominant negative forms of the AMPKalpha2 subunit by use of adenovirus-mediated gene transfer. Overexpression of the dominant negative mutant had no effect on AICAR-induced glucose transport in adipocytes, although AMPK activation was almost completely abolished. This suggests that AICAR-induced glucose uptake by 3T3-L1 adipocytes is independent of AMPK activation. By contrast, overexpression of the dominant negative AMPKalpha2 mutant in muscle markedly suppressed both AICAR-induced glucose uptake and AMPK activation, although insulin-induced uptake was unaffected. Overexpression of the wild-type AMPKalpha2 subunit significantly increased AMPK activity in muscle but did not enhance glucose uptake. Thus, although AMPK activation may not, by itself, be sufficient to increase glucose transport, it appears essential for AICAR-induced glucose uptake in muscle. 相似文献
95.
Sugita Mamoru; Luo Lijun; Ohta Masaru; Itadani Hiraku; Matsubayashi Tohru; Sugiura Masahiro 《DNA research》1995,2(2):71-76
A part of the tRNALeu (UAA) gene containing a 240-nucleotidegroup I intron was amplified by PCR from cyanobacterium SynechococcusPCC 6301 genomic DNA. The pre-tRNA synthesized from the clonedPCR product was efficiently self-spliced in vitro under physiologicalconditions. The gene encoding the tRNALeu (UAA), trnL-UAA, wasisolated from a Synechococcus PCC 6301 genomic library and thenucleotide sequence of a 2,167-bp portion was determined. ThetrnL-UAA consists of a 34-bp 5' exon, a 240-bp group I intronand a 50-bp 3' exon. In addition, three open reading frames(ORF1, ORF2 and ORF3) were found in the 5' and 3' flanking regionsof trnL-UAA. The predicted protein sequence of ORF3, which islocated 74-bp upstream from trnL-UAA on the opposite strand,shows 66.2% amino acid identity to that of the SynechocystisPCC 6803 gene encoding subunit L of NADH dehydrogenase (ndhL). 相似文献
96.
Isao Matsui Shuzo Otani Masaharu Kamei Seiji Morisawa 《Chemico-biological interactions》1984,51(2):141-149
Effect of sodium butyrate on DNA synthesis and the induction of ornithine decarboxylase (EC 4.1.1.17), a rate-limiting enzyme of polyamine biosynthesis, was studied in phytohemagglutinin(PHA)-stimulated bovine lymphocytes. Millimolar concentrations of butyrate completely inhibited the incorporation of [3H] thymidine into the acid-insoluble fraction and reversibly suppressed the induction of ornithine decarboxylase. Other shortchain fatty acids were much less active than butyrate. These results suggest that the suppression of ornithine decarboxylase activity may be one of the reasons for the inhibition of DNA synthesis with butyrate in bovine lymphocytes, because our previous experimental results have shown that the induction of ornithine decarboxylase closely correlates with the DNA synthesis in growth-stimulated cells. 相似文献
97.
Hiraku Y Sugimoto J Yamaguchi T Kawanishi S 《Archives of biochemistry and biophysics》1999,365(1):62-70
We investigated DNA damage induced by aminoacetone, a metabolite of threonine and glycine. Pulsed-field gel electrophoresis revealed that aminoacetone caused cellular DNA cleavage. Aminoacetone increased the amount of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in human cultured cells in a dose-dependent manner. The formation of 8-oxodG in calf thymus DNA increased due to aminoacetone only in the presence of Cu(II). DNA ladder formation was observed at higher concentrations of aminoacetone than those causing DNA cleavage. Flow cytometry showed that aminoacetone enhanced the generation of hydrogen peroxide (H2O2) in cultured cells. Aminoacetone caused damage to 32P-5'-end-labeled DNA fragments, obtained from the human c-Ha-ras-1 and p53 genes, at cytosine and thymine residues in the presence of Cu(II). Catalase and bathocuproine inhibited DNA damage, suggesting that H2O2 and Cu(I) were involved. Analysis of the products generated from aminoacetone revealed that aminoacetone underwent Cu(II)-mediated autoxidation in two different pathways: the major pathway in which methylglyoxal and NH+4 are generated and the minor pathway in which 2,5-dimethylpyrazine is formed through condensation of two molecules of aminoacetone. These findings suggest that H2O2 generated by the autoxidation of aminoacetone reacts with Cu(I) to form reactive species capable of causing oxidative DNA damage. 相似文献
98.
99.
Toshiya Katano Shin-ichi Nakano Osamu Mitamura Haruko Yoshida Hisayuki Azumi Yoshiki Matsuura Yuji Tanaka Hiraku Maezono Yasuhiro Satoh Takeshi Satoh Yuko Sugiyama Yasunori Watanabe Tetsuro Mimura Yuki Akagashi Hiroshi Machida Valentin V. Drucker Irina Tikhonova Olga Belykh Vladimir A. Fialkov Myung-Soo Han Sung-Ho Kang Masahito Sugiyama 《Limnology》2008,9(2):105-114
In Lake Baikal, picocyanobacteria are the most important primary producers during the summer. Freshwater picocyanobacteria
are discriminated into either the phycoerythrin (PE)-rich or the phycocyanin (PC)-rich types according to their pigment composition.
The distributions of these two types of picocyanobacteria were investigated in Barguzin Bay. The PC-rich type accounted for
>98% of the total picocyanobacteria at the station near the shore of the bay where river water flows directly in. In the offshore
area of the lake, all of the picocyanobacteria cells were of the PE-rich type. In addition, the occurrence of the PC-rich
type was restricted to the station, where the attenuation coefficient exceeded 0.25 m−1. Near the shore, where the turbidity was high (>1 NTU), the cell densities of both the PE- and PC-rich types increased away
from the river mouth. This indicates that the PC-rich type cells grow near the shore of the bay where turbidity is high. Since
the PC-rich type could not grow well when cells were incubated in offshore lake water, restricted distribution of the PC-rich
type could also be explained by their growth capability. The present study clearly demonstrated the shift in the pigment type
composition of picocyanobacteria from the coastal to the pelagic zone of Lake Baikal. The co-existence of the two pigment
types probably enables the abundance of the picocyanobacterial community to be stable over a broader range of environmental
conditions than would be possible for a single pigment type. 相似文献
100.
Satomi Tanimoto Tohru Nakazawa Yoshihisa Kudo Masaaki Morisawa 《Molecular reproduction and development》1994,39(4):409-414
Flux of K+ and changes in intracellular Ca2+ in the sperm of salmonid fishes were measured with spectrophotometry, ion electrode, microscopic fluorometry, and radioisotope accumulation. Release of K+ occurred at the initiation of sperm motility which is induced by decrease in external K+ and the K+ efflux and sperm motility were inhibited by K+ channel blockers. Intracellular Ca2+ increased within a short period in K+- free condition, and the accumulation of 45Ca in sperm cells was higher in motile sperm than that in immotile sperm. The efflux of K+ and the increase in intracellular Ca2+ were suppressed when external K+ concentration increased, i.e., sperm remained immotile. These results suggest that efflux of K+ through K+ channel and subseqent increase in intracellular Ca2+ are prerequisite for the initiation of sperm motility. © 1994 Wiley-Liss, Inc. 相似文献