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Biomedical subjects

M Shimomura

Publications and source records attributed to M Shimomura.

14 recordsLinked to original sources
PubMed1992

32P-postlabeling analysis of DNA adducts in rats during estrogen-induced hepatocarcinogenesis and effect of tamoxifen on DNA adduct level.

DNA adduct formation in the liver, pancreas, kidneys and uterus in ethynylestradiol (EE)-induced carcinogenesis and the effect of tamoxifen (TAM) on DNA adduct formation were evaluated in female Wistar JCL rats using the 32P-postlabeling method. Hyperplastic nodules were noted in the liver of all rats 4 months after the first oral administration of 0.075 mg of EE, and hepatocellular carcinoma was detected in 8.1% of rats treated with EE for 12 months. DNA adducts increased in the liver for 4 months, reaching a level of 7.3 adducts/10(7) nucleotides and decreasing thereafter. Formation of DNA adducts was also noted in the pancreas and kidney, but the adduct levels were lower than those in the liver. TAM inhibited estrogen receptors (ER) in liver tissues and completely suppressed the development of hyperplastic nodules or hepatocellular carcinoma but did not affect DNA adduct formation in the liver. In this model, therefore, EE is considered to cause mutations of hepatocytes due to DNA adduct formation without mediation by ER and to induce initiated cells to develop into hepatocellular carcinoma in the presence of ER-mediated hormonal activities.

Animals↗
PubMed1992

Sequence-specific DNA recognition by basic peptides.

A chiral template with C2 symmetry has been used for modeling a dimeric interface of DNA binding protein. An oligopeptide derived from the basic region of MyoD, a recently described "helix-loop-helix" class of DNA binding protein, has been tethered to the template. Among the four models which differ in chirality and polarity with respect to the arrangement of two subunits, only one dimer model with right-handed and C-terminus to C-terminus arrangement of the peptide subunits binds DNA containing native MyoD binding sequence.

DNA↗
PubMed1991

Processing of Kanji and Kana characters within Japanese words.

Two experiments were conducted to examine the temporal relationship between whole-word and character processing in Japanese. Two kinds of Japanese script were used as stimuli: Kanji, an ideographic script, and Kana, a syllabic script. In Experiment 1, Kanji word processing and Kanji character processing were examined using a successive visual comparison task. The whole-word advantage (Marmurek, 1986) was not found. In Experiment 2, Kana words and characters were used. As in Experiment 1, no whole-word advantage was found. The absence of the whole-word advantage is attributed to the fact that Kanji and Kana characters represent higher level units of processing than alphabetic letters. The difference between word and nonword processing was shown by manipulations of the visual similarity and the homophony between stimuli presented successively. Visual similarity affected both words and nonwords, whereas homophony affected words only.

Attention↗
PubMed1991

[Multidisciplinary therapy after hepatectomy for hepatocellular carcinoma from the view point of tumor recurrence].

This study was performed to elucidate the risk factors of early recurrence after hepatectomy for the 112 patients with hepatocellular carcinoma, excluding absolute non-curative resections and operative deaths, and effects of early prophylactic management were evaluated. In Cox's multivariate analysis, 3 pathological factors of portal vein invasion, intrahepatic metastasis and capsule formation or capsule infiltration as well as the nuclear DNA ploidy pattern were significantly correlated to postoperative recurrence. The patients with 2 or more pathological factors or with DNA aneuploid tumors developed recurrence at early postoperative period. However, even in the DNA aneuploid tumors, the patients with high DNA index and low S-phase fraction showed relatively better prognosis. Argyrophilic proteins of nucleolar organizer regions (AgNOR) were also correlated well to nuclear DNA analysis, showing one of the good indicators for estimating biological malignant nature. Therefore, intra-arterial regional chemolipiodolization therapy should be performed for these high risk patients at early period after hepatectomy. With these managements we have been getting much lower incidence of early recurrence.

Carcinoma, Hepatocellular↗
PubMed1991

DNA recognition by synthetic peptides as a model for the dimeric proteins.

A Chiral template possessing a C2 axis has been utilized to study an effect in the dimer formation of oligopeptides. Oligopeptide rich in basic amino acids are used as subunits that would interact with DNA, and the subunits are aligned according to the C2 axis of the template. Synthesis, characterization and DNA binding study of these dimeric peptides will be discussed.

DNA↗
PubMed1990

Sphingolipids and glycerolipids. I. Chemical structures and ionophoretic activities of soya-cerebrosides I and II from soybean.

Two glycosphingolipids named soya-cerebrosides I and II were isolated from soybean, the seeds of Glycine max Merrill (Leguminosae), and their chemical structures have been elucidated on the basis of physicochemical evidence and several chemical degradation reactions. By using a newly constructed liquid membrane-type apparatus (W-08) for measurement of ion-transport and ion-binding activities and by employing a method using human erythrocyte membranes for measurement of ion-permeability, it has been found that soya-cerebroside II exhibits ionophoretic activity for Ca2+ ion.

Cerebrosides↗
PubMed1990

Cardiac sports rehabilitation for patients with ischemic heart disease.

This paper summarizes data gathered from an 8 years sports cardiac rehabilitation program at Kyoto University and satellite hospital (Takeda Hospital). In total, 185 patients were rehabilitated under our original program with no serious cardiac accidents. Compliance was 58.2% after 6 months of this rehabilitation. In patients selected to evaluate the value of rehabilitation, exercise study with treadmill and 201Tl scintigraphic study showed improvement in exercise tolerance (in 58% of patients) and in perfusion on exercise (in 40%). Coronary angiographic study showed regression of arterial narrowing in 16% of the patients studied. We conclude that in addition to emotional and psychological support, our sports cardiac rehabilitation is safe and effective in improving exercise tolerance and cardiac perfusion.

Coronary Angiography↗
PubMed1977

Desulfuration of l-cysteine through transamination and transsulfuration in rat liver.

Desulfuration of L-cysteine by rat liver via a pathway of transamination followed by transsulfuration was studied using cyanide as a sulfur acceptor. More than a 5-fold increase in formation of thiocyanate from L-cysteine and cyanide was observed in the presence of 2-oxoglutarate and pyruvate. L-Cysteine aminotransferase and 3-mercaptopyruvate sulfurtransferase activities in the same preparations were also determined. It was concluded that L-cysteine was desulfurated through transamination and transsulfuration of the resulting 3-mercaptopyruvate, and that the rate-limiting step appears to be the transamination reaction.

Animals↗
PubMed1977

Effects of maleic acid administration on urinary excretion of DCEC, and on tissue protein, in the rat.

Administration of maleic acid to rats caused increased urinary excretion of S-(1,2-dicarboxyethyl)cysteine [DCEC] and increased binding of maleic acid to tissue proteins. The trichloroacetic acid precipitate from a combined fraction of supernatant and microsome gave the maximum amount of DCEC after hydrolysis. It would appear that aminoaciduria produced by maleate was partially due to increased destruction of some succinylated tissue proteins.

Amino Acids, Dicarboxylic↗
PubMed1977

Transaminase of L-cysteine in rat liver mitochondria.

Transamination of L-cysteine in rat liver was examined. Specific activity of the reaction in mitochondria was found higher than that in cytosol. The mitochondrial reaction was shown to be catalyzed by two different enzymes. The first was active with 2-oxoglutarate and inactivated by heating at 60 degrees C for 10 minutes; the activity was protected from heat inactivation by the presence of 2-oxoglutarate. The second enzyme was active with pyruvate and more stable than the first under heat treatment; 2-oxoglutarate had little protective effect on this second enzyme. The two enzyme activities were separated by heat treatment and ammonium sulfate fractionation.

Animals↗
PubMed1976

Studies on a patient with iminopeptiduria. I. Identification of urinary iminopeptides.

A patient suffering from recurrent ulcers on the legs was found to excrete large amounts of iminodipeptides in the urine. Among the iminodipeptides excreted, Glu-Hyp, Asp-Pro, Glu-Pro, Leu-Hyp, Gly-Pro, Thr-Pro, Ser-Pro, Ala-Pro, Val-Pro, Ile-Pro, Leu-Pro, and Phe-Pro were identified and their quantities estimated. Some of the iminopeptides had to be synthesized for purposes of identification.

Amino Acid Metabolism, Inborn Errors↗