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Biomedical subjects

S Shimizu

Publications and source records attributed to S Shimizu.

At least 163 records · Page 9Linked to original sources
PubMed2000

Gene cloning and overproduction of low-specificity D-threonine aldolase from Alcaligenes xylosoxidans and its application for production of a key intermediate for parkinsonism drug.

The dtaAX gene encoding a pyridoxal 5'-phosphate (pyridoxal-P)-dependent low-specificity D-threonine aldolase was cloned from the chromosomal DNA of Alcaligenes xylosoxidans IFO 12669. It contains an open reading frame consisting of 1,134 nucleotides corresponding to 377 amino acid residues. The predicted amino acid sequence displayed 54% identity with that of D-threonine aldolase from gram-positive bacteria Arthrobacter sp. DK-38, but showed no significant similarity with those of other known pyridoxal-P enzymes. This gram-negative bacterial enzyme was highly overproduced in recombinant Escherichia coli cells, and the specific activity of the enzyme in the cell extract was as high as 18 U/mg (purified enzyme 38.6 U/mg), which was 6,000 times higher than that from the wild-type Alcaligenes cell extract. The recombinant enzyme was thus feasibly purified to homogeneity by ammonium sulfate fractionation and DEAE-Toyopearl chromatography steps. The recombinant low-specificity D-threonine aldolase was shown to be an efficient biocatalyst for resolution of L-beta-3,4-methylenedioxyphenylserine, an intermediate for production of a therapeutic drug for Parkinson's disease.

Alcaligenes↗
PubMed2000

Genetic mapping of the rat mutation creeping and evaluation of its positional candidate gene reelin.

We have previously described a rat autosomal recessive mutation, creeping (cre), causing severe ataxia and disarrangement of neuronal cells in the central nervous system. The mutant strain has recently been successfully inbred, named Komeda Zucker creeping (KZC) rat. In the present study, we have performed a genetic analysis of the creeping mutation, and mapped it to rat Chromosome (Chr) 4. Comparative mapping, together with the similarity of the phenotype, suggested that the creeping mutation is homologous to the mouse reeler mutation. In fact, reelin expression was markedly reduced in the homozygous mutant (cre/cre) animals compared with the normal littermates. Thus, the KZC rat should become a useful biological model with a novel mutation in the reelin gene.

Animals↗
PubMed2000

Laparoscopically assisted distal gastrectomy for early gastric cancer: is it superior to open surgery?

BACKGROUND: The purpose of this study was to compare clinical outcomes between laparoscopically assisted and open distal gastrectomy for early gastric cancer. METHODS: The records of 21 patients who underwent laparoscopically assisted distal gastrectomy (LG) for preoperative diagnosis of intramucosal gastric carcinoma between January 1996 and August 1998 were reviewed and compared with those of 31 open distal gastrectomy patients during the same period. RESULTS: Age, gender, and size and histologic differentiation of the lesions were matched. Those located at the body of the stomach (p = 0.011) and those macroscopically depressed (p = 0.049) were subjected more frequently to open surgery. Laparoscopically assisted gastrectomy required significantly longer operative time (p < 0.001) with less extensive lymph node dissection (p < 0.001). However, time to start of walking (p = 0.032), time to flatus (p = 0.002), duration of postoperative fever (p = 0.027), and postoperative hospital stay (p = 0.001) were significantly shorter in the LG group, and this group had a lower white blood cell count on the first postoperative day (p = 0.010). Blood loss and time to oral intake were comparable between the groups. Complications included one conversion to open surgery, one leakage, and one stenosis in the LG group, and two leakages and an atelectasis in the OG group. CONCLUSIONS: Although LG requires longer surgical time, this retrospective study suggests that it is superior to open surgery in terms of faster postoperative recoveries, shorter hospital stays, and cosmetic outcomes.

Adenocarcinoma↗
PubMed2000

Age-dependent prevalence of mutations at the GLC1A locus in primary open-angle glaucoma.

PURPOSE: To screen a population with primary open-angle glaucoma for mutations in the gene that encodes the trabecular meshwork inducible glucocorticoid response protein (TIGR), also known as myocilin (MYOC). METHODS: Ophthalmologic information was collected for study subjects with primary open-angle glaucoma and their relatives. Mutation screening of 74 primary open-angle glaucoma probands was conducted by sequencing TIGR/MYOC coding sequence and splice sites. RESULTS: In 23 families we detected 13 nonsynonymous sequence changes, nine of which appear to be mutations likely to cause or contribute to primary open-angle glaucoma. Two mutations, Arg272Gly and Ile499Ser, and one nonsynonymous sequence variant, Asn57Asp, are novel. We found mutations in nine of 25 juvenile glaucoma probands (36%) and two of 49 adult-onset glaucoma probands (4%). Age classification of families rather than individual probands revealed mutations in three of nine families with strictly juvenile primary open-angle glaucoma (33%), and no mutations in 39 families with strictly adult-onset primary open-angle glaucoma (0%). In families with mixed-onset primary open-angle glaucoma containing both juvenile primary open-angle glaucoma and adult-onset primary open-angle glaucoma cases, we found mutations in eight of 26 families (31%). CONCLUSIONS: Our data suggest that Gly252Arg, Arg272Gly, Glu323Lys, Gln368STOP, Pro370Leu, Thr377Met, Val426Phe, Ile477Asn, and Ile499Ser are likely to play roles that cause or contribute to the etiology of autosomal dominant primary open-angle glaucoma. Our finding of more TIGR/MYOC mutations in families with mixed-onset primary open-angle glaucoma than in the families with strictly adult-onset primary open-angle glaucoma implies that the presence of relatives with juvenile primary open-angle glaucoma in a family could be used as a basis for identifying a subset of the population with adult-onset primary open-angle glaucoma with higher prevalence of TIGR/MYOC mutations. To address this issue, and to refine estimations of mutation prevalence in these age-defined subpopulations, prospective study of a larger population ascertained entirely through adult-onset primary open-angle glaucoma probands will be needed.

Adolescent↗
PubMed2000

Expression of human telomerase subunit genes in primary lung cancer and its clinical significance.

BACKGROUND: Three major components of human telomerase, RNA component (hTERC), telomerase-associated protein (TEP1), and catalytic subunit (hTERT) have been cloned recently. The aim of this study was to examine the expression of these genes and to search for clinical usefulness. METHODS: Expression of these genes was evaluated by reverse transcription-polymerase chain reaction in 92 human lung cancers and in 32 non-neoplastic lung tissues. In 15 patients, both telomerase activity by telomeric repeat amplification protocol assay and expression were evaluated. RESULTS: hTERT expression was best associated with telomerase activity with a concordance of 77%. In 92 lung cancer tissues, hTERC, TEP1, and hTERT were expressed in 100%, 93%, and 89%, respectively. Whereas most adjacent non-neoplastic lung tissues expressed hTERC and TEP1 (94% and 100%, respectively), hTERT was detected in only 1 of 32 normal lungs. However, there was no relationship between hTERT expression and clinicopathologic features. CONCLUSIONS: hTERT expression can be a surrogate for telomerase activity that may serve as a novel biomarker of lung cancer with high specificity and sensitivity.

Adenocarcinoma↗
PubMed2000

Cyclosporin A, but not bursectomy, abolishes the protective immunity of chickens against Leucocytozoon caulleryi.

Chickens that survive primary infection with Leucocytozoon caulleryi show strong resistance to reinfection. Using bursectomized (BX) or cyclosporin A (CsA)-treated chickens, we performed experiments to determine which type of immunity, humoral or cellular immunity, plays an important role in the resistance of chickens against reinfection with L. caulleryi. BX chickens were inoculated with 2, 20 or 200 sporozoites of L. caulleryi intravenously at 3 weeks of age. Some BX chickens which were inoculated with 2 or 20 sporozoites survived the primary infection. These birds had no parasites in their peripheral blood after challenge infection with 5 x 10(3) sporozoites, even though they had no antibody to L. caulleryi. In contrast, CsA-treated chickens had parasitemia, serum-soluble antigen and antibodies, as did untreated chickens during primary infection. After secondary infection, CsA-treated chickens had parasitemia and serum-soluble antigen, even though they had specific antibodies to L. caulleryi whereas untreated chickens showed no parasitemia. The number of CD4(+), CD8(+), T cell receptor (TCR) alpha ss-bearing cells and TCRgamma delta-bearing cells decreased markedly in the peripheral blood of CsA-treated chickens compared to those of untreated chickens. Lymphocyte proliferation in response to concanavalin A, and T cell growth factor production, were also markedly suppressed in CsA-treated chickens. These results suggest that cell-mediated immunity plays an important role in the development of resistance of chickens against reinfection with L. caulleryi.

Animals↗
PubMed2000

An integrated service digital network (ISDN)-based international telecommunication between Samsung Medical Center and Hokkaido University using telecommunication helped radiotherapy planning and information system (THERAPIS).

This study introduces the integrated service digital network (ISDN)-based international teleradiotherapy system (THERAPIS) in radiation oncology between hospitals in Seoul, South Korea and in Sapporo, Japan. THERAPIS has the following functions: (1) exchange of patient's image data, (2) real-time teleconference, and (3) communication of the treatment planning, dose calculation and distribution, and of portal verification images between the remote hospitals. Our preliminary results of applications on eight patients demonstrated that the international telecommunication using THERAPIS was clinically useful and satisfactory with sufficient bandwidth for the transfer of patient data for clinical use in radiation oncology.

Japan↗
PubMed2000

Nitrile hydrolases.

A number of nitrile-related enzymes have been screened over the past year for use in synthetic applications. There have also been significant advances in our understanding of the structures and modes of regulation of metal-containing nitrile hydratases. Enzyme structural characterization has provided new insights into how the molecular structure determines the enzyme function and how an enzyme can be endowed with new properties. This information has important implications for potential future applications other than the present industrial production of acrylamide and nicotinamide.

Aminohydrolases↗
PubMed2000

Involvement of reactive oxygen species and nitric oxide in gastric ischemia-reperfusion injury in rats: protective effect of tetrahydrobiopterin.

The purpose of this study was to examine whether tetrahydrobiopterin (BH4), a cofactor of nitric oxide (NO) synthase, attenuates gastric ischemia-reperfusion injury induced by clamping of the celiac artery. Gastric injury was assessed by a formation of gastric mucosal erosions. The gastric injury was observed at 30 and 60 min after reperfusion following 30-min ischemia and was reduced by superoxide dismutase (SOD), catalase, or NO synthase inhibitors. Therefore, reactive oxygen species (ROS) and NO seem to be implicated in the ischemia-reperfusion injury. Treatment with BH4 reduced the ischemia-reperfusion injury. Pretreatment with sepiapterin, a precursor of BH4, also reduced the ischemia-reperfusion injury with an increase in BH4 content in serum and stomach. Both the increase in BH4 content and the protective effect of sepiapterin were prevented of pretreatment with N-acetylserotonin, an inhibitor of BH4 synthesis. These results suggest that the increase in BH4 content may protect against gastric ischemia-reperfusion injury via reduction of ROS and/or NO toxicity. BH4 might be useful as a therapeutic agent for gastric ischemia-reperfusion injury.

Animals↗
PubMed2000

Administration of bacterial lipopolysaccharide to rats induces heme oxygenase-1 and formation of antioxidant bilirubin in the intestinal mucosa.

Heme oxygenase (HO)-1, the rate-limiting enzyme in heme degradation, is induced by oxidative stress and its major end product, bilirubin, is a potent physiological antioxidant. We studied the induction of HO-1 and bilirubin production in intestinal mucosa using a rat model of sepsis. E. coli lipopolysaccharide was administered intraperitonealy to male Wistar rats and intestinal mucosa was harvested. Intestinal lipid peroxides increased significantly at 1 hr and peaked at 170% of the control value at 5 hr. GSH significantly decreased at 3 hr, reaching the nadir of 50% of the control value at 5 hr. HO-1 mRNA was maximally induced fivefold at 3 hr and HO-1 protein maximally increased to 10 times the control value at 7.5 hr. Both bilirubin and bilirubin oxidative metabolites were maximally increased at 10 hr, to 4.3 and 3.7 times the control value, respectively. These data suggest that oxidative stress in sepsis quickly induces HO-1 in intestinal mucosa and that subsequent production of bilirubin works as an antioxidant. The small intestinal mucosa is an active participant in the general response to sepsis.

Animals↗
PubMed2000

VDAC regulation by the Bcl-2 family of proteins.

The Bcl-2 family of proteins consists of anti-apoptotic and pro-apoptotic members, which determine the life or death of cells by altering mitochondrial membrane permeability. Pro-apoptotic Bcl-2 family members increase mitochondrial membrane permeability, resulting in the release of mitochondrial apoptogenic factors such as cytochrome c that activates death proteases called caspases, whereas anti-apoptotic family members prevent this increase of mitochondrial membrane permeability. The release of cytochrome c is central to apoptotic signal transduction in mammals, and has been studied extensively, leading to the development of several models for cytochrome c release including rupture of the mitochondrial outer membrane and involvement of specific channels. This article describes the important role of a mitochondrial outer membrane channel, the voltage-dependent anion channel (VDAC), in apoptogenic cytochrome c release and its regulation by Bcl-2 family members, and also discusses the molecular architecture of the life - death switch in mammalian cells. Cell Death and Differentiation (2000) 7, 1174 - 1181

Animals↗
PubMed2000

Natural disasters and alcohol consumption in a cultural context: the Great Hanshin Earthquake in Japan.

AIMS: To assess changes in alcohol consumption attributable to the Great Hanshin Earthquake to test the assumption that alcohol consumption increases after natural disasters. METHODS: Quarterly alcohol sales figures were compared for three periods: before, immediately after and subsequent to the Great Hanshin Earthquake in three areas of the Hyogo prefecture: the severely affected area, the moderately affected area and the unaffected area. Possible confounding by population movement, damage to retail outlets and normal variation in sales, was assessed. FINDINGS: The quantity of alcoholic beverages consumed in the heavily damaged areas as well as throughout the prefecture decreased from the 1994 pre-disaster level, both immediately after the Great Hanshin Earthquake (January-March 1995) and 2 years after the disaster. This finding remained once possible confounding factors were taken into consideration. CONCLUSIONS: More attention should be placed on drinking in the cultural context where a disaster occurs. It may sometimes deter, rather than encourage, drinking among the affected population.

Alcohol Drinking↗
PubMed2000

3,4-Dihydrocoumarin hydrolase with haloperoxidase activity from Acinetobacter calcoaceticus F46.

A novel lactonohydrolase, an enzyme that catalyzes the hydrolysis of 3,4-dihydrocoumarin, was purified 375-fold to apparent homogeneity, with a 22.7% overall recovery, from Acinetobacter calcoaceticus F46, which was isolated as a fluorene-assimilating micro-organism. The molecular mass of the native enzyme, as estimated by high-performance gel-permeation chromatography, is 56 kDa, and the subunit molecular mass is 30 kDa. The enzyme specifically hydrolyzes 3,4-dihydrocoumarin, and the Km and Vmax for 3,4-dihydrocoumarin are 0.806 mM and 4760 U.mg-1, respectively. The N-terminal and internal amino acid sequences of the enzyme show high similarity to those of bacterial non-heme haloperoxidases. The enzyme exhibits brominating activity with monochlorodimedon in the presence of H2O2 and 3, 4-dihydrocoumarin or an organic acid, such as acetate and n-butyrate.

Acids, Acyclic↗
PubMed2000

Ultrastructure of early phase hepatic metastasis of human colon carcinoma cells with special reference to desmosomal junctions with hepatocytes.

To demonstrate ultrastructural events in the early phase of hepatic metastasis of human colon carcinoma, we intrasplenically injected a highly metastasizable, human colon carcinoma cell line LM-H3 (1 x 10(6) cells) into nude mice, and electron microscopically investigated the hepatic metastasis. At 24 h, tumor cells adhered to the endothelial wall of terminal portal venules and periportal sinusoids. At 48-72 h, after extravasation, they deeply invaded the hepatic cell plate and the interstitial tissue of the portal tract, in which they underwent proliferation and made the metastatic foci. Tumor cells were linked with each other or with surrounding hepatocytes by desmosomes. Desmosomes were maintained during the mitosis. When invading tumor cells were exposed to the bile canaliculi, they generated microvilli on the surface. Microvilli were also formed at the luminal surface of intracytoplasmic inclusions. In the interstitial tissue of the portal tract, tumor cells were closely associated with fibroblasts. However, no junctional specializations were seen between them. The present study demonstrated that human colon carcinoma cell line LM-H3 formed desmosomes with hepatocytes soon after invasion of the hepatic cell plate, suggesting the regulatory role of an interaction with hepatocytes in the growth of metastatic foci within the liver parenchyma.

Animals↗
PubMed2000

Temporal and spatial dispersion of repolarization during premature impulse propagation in human intact ventricular muscle: comparison between single vs double premature stimulation.

AIMS: This study was performed to determine whether or not the kinetics of action potential duration restitution during double premature stimuli (S3) differ from that during single premature stimuli (S2) in the human intact right ventricle. METHODS AND RESULTS: A monophasic action potential (MAP) was simultaneously recorded from the right ventricular apex (RVA) and outflow tract (RVOT) during programmed ventricular pacing in 11 patients with symptomatic bradyarrhythmias (five males, six females, mean age 58 years). In the five most recent patients, the RV pressure and its dp/dt were also obtained during the protocol. A substantial difference in the restitution of the MAP duration (MAPD) between S2 and S3 was observed at short diastolic intervals (< l00 ms), that is, the restitution curve of S2 showed an early biphasic pattern (upward hump), while such a phenomenon was not seen during the restitution of S3. All the quantitative parameters of MAPD restitution representing its kinetics were significantly greater in S3 than S2. Maximum attainable dispersion of repolarization between the two MAPs was significantly greater during S3 than S2 (76 +/- 17 vs 59 +/- 17 ms, P<0.05) and was mainly caused by the difference in the MAPD difference, thus by the difference in the restitution kinetics of S2 and S3. The dp/dt of the RV pressure was significantly greater during S3 than S2 for all diastolic intervals tested. CONCLUSION: It was concluded that similar to previously reported canine experimental studies, the APD restitution of S3 is substantially different from that of S2 in the human intact ventricle (endocardium).

Action Potentials↗
PubMed2000

Biochemical characterization, cloning, and sequencing of ADP-dependent (AMP-forming) glucokinase from two hyperthermophilic archaea, Pyrococcus furiosus and Thermococcus litoralis.

The ADP-dependent (AMP-forming) glucokinases from the hyperthermophilic archaea Pyrococcus furiosus and Thermococcus litoralis catalyze the phosphorylation of glucose using ADP as the essential phosphoryl group donor. Both enzymes were purified to homogeneity and characterized with regard to each other. The enzymes had similar enzymological properties as to substrate specificity, coenzyme specificity, optimum pH, and thermostability. However, a difference was observed in the subunit composition; while the T. litoralis enzyme is a monomer with a molecular mass of 52 kDa, the P. furiosus enzyme has a molecular mass of about 100 kDa and consists of two subunits with identical molecular masses of 47 kDa. The genes encoding these enzymes were cloned and sequenced. The gene for the P. furiosus enzyme contains an open reading frame for 455 amino acids with a molecular weight of 51,265, and that for the T. litoralis enzyme contains an open reading frame for 467 amino acids with a molecular weight of 53,621. About 59% similarity in amino acid sequence was observed between these two enzymes, whereas they did not show similarity with any ATP-dependent kinases that have been reported so far. In addition, two phosphate binding domains, and adenosine and glucose binding motifs commonly conserved in the eukaryotic hexokinase family were not observed.

Amino Acid Sequence↗