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Biomedical subjects

T Mizuno

Publications and source records attributed to T Mizuno.

At least 73 records · Page 4Linked to original sources
PubMed2001

[Complete response in a case of advanced gastric cancer with liver and intra-abdominal lymph node metastases treated by combined chemotherapy of TS-1 and CDDP].

A 67-year-old male patient with gastric cancer of Borrmann type 2 and liver and intra-abdominal lymph node metastases was treated by combined chemotherapy of TS-1 and CDDP TS-1 (100 mg/day) was administered for 14 days followed by 14 days rest as one course. CDDP (70 mg/m2) was administered in 24-hour continuous intravenous infusion at 8 days after the start of TS-1. After 3 courses of treatment, X-ray and endoscopic examinations revealed complete disappearance of the primary tumor and no cancer cells were detected by endoscopic biopsy. A CT-scan also showed complete disappearance of metastatic sites. This combined chemotherapy was finished after 5 courses, and no high grade toxicities (WHO grade 3 or 4), specifically nausea, diarrhea, or leucocytopenia, were seen. This TS-1/CDDP chemotherapy seemed to be effective for advanced gastric cancer in view of toxicities, antitumor effect and QOL of the patient.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2000

The human homolog of Saccharomyces cerevisiae Mcm10 interacts with replication factors and dissociates from nuclease-resistant nuclear structures in G(2) phase.

Mcm10 (Dna43), first identified in Saccharomyces cerevisiae, is an essential protein which functions in the initiation of DNA synthesis. Mcm10 is a nuclear protein that is localized to replication origins and mediates the interaction of the Mcm2-7 complex with replication origins. We identified and cloned a human cDNA whose product was structurally homologous to the yeast Mcm10 protein. Human Mcm10 (HsMcm10) is a 98-kDa protein of 874 amino acids which shows 23 and 21% overall similarity to Schizosaccharomyces pombe Cdc23 and S. cerevisiae Mcm10, respectively. The messenger RNA level of HsMcm10 increased at the G(1)/S-boundary when quiescent human NB1-RGB cells were induced to proliferate as is the case of many replication factors. HsMcm10 associated with nuclease-resistant nuclear structures throughout S phase and dissociated from it in G(2) phase. HsMcm10 associated with human Orc2 protein when overexpressed in COS-1 cells. HsMcm10 also interacted with Orc2, Mcm2 and Mcm6 proteins in the yeast two-hybrid system. These results suggest that HsMcm10 may function in DNA replication through the interaction with Orc and Mcm2-7 complexes.

Amino Acid Sequence↗
PubMed2000

Distinct regulation of brain mitochondrial carrier protein-1 and uncoupling protein-2 genes in the rat brain during cold exposure and aging.

Mitochondrial uncoupling proteins (UCPs) have been postulated to be regulators of thermogenesis, energy balance, and oxidative stress. Brain mitochondrial carrier protein-1 (BMCP1) is a new member of the UCP family, but little is known about the gene regulation and the role of BMCP1 in the central nervous system. In the present study, we first cloned BMCP1 cDNA encoding 325 amino acids from rat brain. The BMCP1 mRNA showed a distinct distribution pattern compared with that of UCP2 gene in human brain. Cold exposure did not affect the mRNA levels of BMCP1 and UCP2 in rat whole brain, but did increase the expression of UCP2 in the spinal cord. The mRNA level of BMCP1 in the brain of 26-month-old rats was decreased by 30% and that of UCP2 increased by 60% compared with the levels in 6-month-old rats. These results suggest differential roles of BMCP1 and UCP2 in thermoregulation and aging.

Acclimatization↗
PubMed2000

High precision NMR structure of YhhP, a novel Escherichia coli protein implicated in cell division.

YhhP, a small protein of 81 amino acid residues encoded by the yhhP gene in the Escherichia coli database, is implicated in cell division although the precise biological function of this protein has not been yet identified. A variety of microorganisms have similar proteins, all of which contain a common CPxP sequence motif in the N-terminal region. We have determined the three-dimensional solution structure of YhhP by NMR spectroscopy in order to obtain insight into its biological function. It folds into a two-layered alpha/beta-sandwich structure with a betaalphabetaalphabetabeta fold, comprising a mixed four-stranded beta-sheet stacked against two alpha-helices, both of which are nearly parallel to the strands of the beta-sheet. The CPxP motif plays a significant structural role in stabilizing the first helix as a part of the new type N-capping box where the Cys-Pro peptide bond adopts a cis configuration. The structure of YhhP displays a striking resemblance to the C-terminal ribosome-binding domain of translation initiation factor IF3 (IF3C). In addition, the surface charge distribution of the RNA-recognition helix of IF3C is nearly the same as that of the corresponding helix of YhhP. These results suggest a structure-based hypothesis in which binding to an RNA target plays an essential role in the function of this ubiquitous protein.

Amino Acid Sequence↗
PubMed2000

Dehydroaltenusin, a mammalian DNA polymerase alpha inhibitor.

Dehydroaltenusin was found to be an inhibitor of mammalian DNA polymerase alpha (pol alpha) in vitro. Surprisingly, among the polymerases and DNA metabolic enzymes tested, dehydroaltenusin inhibited only mammalian pol alpha. Dehydroaltenusin did not influence the activities of the other replicative DNA polymerases, such as delta and epsilon; it also showed no effect even on the pol alpha activity from another vertebrate (fish) or plant species. The inhibitory effect of dehydroaltenusin on mammalian pol alpha was dose-dependent, and 50% inhibition was observed at a concentration of 0.5 microm. Dehydroaltenusin-induced inhibition of mammalian pol alpha activity was competitive with the template-primer and non-competitive with the dNTP substrate. BIAcore analysis demonstrated that dehydroaltenusin bound to the core domain of the largest subunit, p180, of mouse pol alpha, which has catalytic activity, but did not bind to the smallest subunit or the DNA primase p46 of mouse pol alpha. These results suggest that the dehydroaltenusin molecule competes with the template-primer molecule on its binding site of the catalytic domain of mammalian pol alpha, binds to the site, and simultaneously disturbs dNTP substrate incorporation into the template-primer.

Animals↗
PubMed2000

Novel RING finger proteins, Air1p and Air2p, interact with Hmt1p and inhibit the arginine methylation of Npl3p.

Heterogeneous nuclear ribonucleoproteins (hnRNPs) are involved in the mRNA processing and export and are post-translationally modified by methylation at arginine residues in their arginine-glycine-rich (RGG) domains. We screened the factors that can interact with the RGG domain of Npl3p only in the presence of Hmt1p with the two-hybrid system in Saccharomyces cerevisiae. An isolated clone, YIL079, encodes a novel RING finger protein that was not directly bound to Npl3p but associated with the N terminus of Hmt1p. Thus, we designated the gene product Air1p (arginine methyltransferase-interacting RING finger protein). Air1p inhibited the Hmt1p-mediated methylation of Npl3p in vitro. Overexpression of Air1p repressed the Hmt1p-dependent growth of cells. Since homology searches indicate that the YDL175 gene product has significant identity (45%) with Air1p, we designated the gene AIR2. Air2p also has a RING finger domain and was bound to Hmt1p. Although single disruption of either gene gave no effect on the cell growth, cells lacking Air1p and Air2p grew at an extremely slow rate with accumulated poly(A)(+) RNA in the nucleus. Thus, Air1p and Air2p may affect mRNA transport by regulating the arginine methylation state of heterogeneous nuclear ribonucleoproteins.

ATP-Binding Cassette Transporters↗
PubMed2000

Twenty-three Cases of Primary Cornea Guttata.

Purpose: An evaluation of the clinical aspects of patients with primary cornea guttata and the morphology of their corneal endothelial cells.Methods: Twenty-three patients who visited Kanazawa Medical University Hospital or related hospitals in Ishikawa or Fukui prefectures and were diagnosed as having primary cornea guttata by slit lamp microscopy and contact specular microscopy underwent an analysis of corneal endothelial cells as well as their clinical status.Results: In 23 cases, the number of men and young people under 30 years of age was low, with 4 and 2 cases respectively. There was no visual impairment due to cornea guttata. In the specular microscopic findings, the size and density of dark areas varied according to each case and there was asymmetry in some cases. The parameters of the endothelial cells, comprising mean cell area, hexagonality, and the coefficient of variation, were almost within normal limits except for one eye of a 79-year-old man who was speculated to be at an early stage of Fuch's endothelial corneal dystrophy. Three cases had received cataract surgery, but showed no statistical changes in endothelial morphology before or after the surgery.Conclusion: Cornea guttata is thought to be a disease which is not uncommon in Japanese people and which does not bring about visual impairment or abnormalities in corneal endothelial cell parameters except for a small number of patients. Such cases with remarkably decreased cell densities should be considered to be at an early stage of Fuch's dystrophy.

Journal Article↗
PubMed2000

Inhibitory effect of stromal cell derived factor-1 on the replication of divergent strains of feline immunodeficiency virus in a feline T-lymphoid cell line.

The effect of a CXC-chemokine, stromal cell derived factor-1 (SDF-1), on the replication of divergent strains of feline immunodeficiency virus (FIV) was examined in order to identify the mechanism of cell entry of FIV. A chemotaxis assay, using a modified Boyden chamber method, confirmed the biological activity of recombinant human (rh) SDF-1 for a feline T-lymphoid cell line (Kumi-1). The viral replication of FIV, as measured by the reverse transcriptase (RT) activity in the culture supernatant, was significantly suppressed by addition of rhSDF-1 in a dose-dependent manner in Kumi-1 cells. Furthermore, PCR analysis of the FIV proviral genome indicated that the inhibitory effect of rhSDF-1 on the replication of FIV in Kumi-1 cells was due to the inhibitory effect in the early event of replication. The inhibitory effect on viral replication by exogenous rhSDF-1 was shown for four divergent FIV isolates of subtypes A, B, and D in Kumi-1 cells.

Animals↗
PubMed2000

Up-regulation of natriuretic peptides in the ventricle of Csx/Nkx2-5 transgenic mice.

A cardiac homeobox-containing gene Csx/Nkx2-5, which is essential for cardiac development, is abundantly expressed in the adult heart as well as in the heart primordia. Targeted disruption of this gene results in embryonic lethality due to abnormal heart morphogenesis. To elucidate the role of Csx/Nkx2-5 in the adult heart, we generated transgenic mice which overexpress human Csx/Nkx2-5. The transgene was expressed abundantly in the heart and the skeletal muscle. mRNA levels of several cardiac genes including natriuretic peptides, CARP, MLC2v, and endogenous Csx/Nkx2-5 were increased in the ventricle of the transgenic mice. Electron microscopic analysis revealed that the ventricular myocardium of the transgenic mice had many secretory granules, which disappeared after administration of vasopressin. These results suggest that Csx/Nkx2-5 regulates many cardiac genes and induces formation of secretory granules in the adult ventricle.

Animals↗
PubMed2000

The SixA phospho-histidine phosphatase modulates the ArcB phosphorelay signal transduction in Escherichia coli.

The Escherichia coli SixA protein is the first discovered prokaryotic phospho-histidine phosphatase, which was implicated in a His-to-Asp phosphorelay. The sixA gene was originally identified as the one that interferes with, at its multi-copy state, the cross-phosphorelay between the histidine-containing phosphotransmitter (HPt) domain of the ArcB anaerobic sensor and its non-cognate OmpR response regulator. Nevertheless, no evidence has been provided that the SixA phosphatase is indeed involved in a signaling circuitry of the authentic ArcB-to-ArcA phosphorelay in a physiologically meaningful manner. In this study, a SixA-deficient mutant was characterized with special reference to the ArcB signaling, which allows E. coli cells to respond to not only external oxygen, but also certain anaerobic respiratory conditions. Here evidence is provided for the first time that the SixA phosphatase is a crucial regulatory factor that is involved in the ArcB signaling, particularly, under certain anaerobic respiratory growth conditions. We propose a novel mechanism, involving an HPt domain and a phospho-histidine phosphatase, by which a given multi-step His-to-Asp signaling can be modulated.

Anaerobiosis↗
PubMed2000

Preferential induction of RET/PTC1 rearrangement by X-ray irradiation.

Ionizing radiation is a well known risk factor of thyroid cancer development, but the mechanism of radiation induced carcinogenesis is not clear. The RET/PTC oncogene, an activated form of the RET proto-oncogene, is frequently observed in papillary thyroid carcinoma (PTC); RET/PTC1, -2 and -3 are known to be the three major forms. High frequencies of RET/PTC rearrangements have been observed in radiation-associated PTC, such as those appearing post-Chernobyl or post-radiotherapy, but the rearrangement types differ between these two populations. We investigated whether a specific type of RET/PTC rearrangement was induced by X-rays in vivo and in vitro. In human normal thyroid tissues transplanted in scid mice, the RET/PTC1 rearrangement was predominantly detected throughout the observation period (up to 60 days) after X-ray exposure of 50 Gy. On the other hand, RET/PTC3 was detected only 7 days after X-irradiation, and no transcript of RET/PTC2 was detected. These results are supported by the results of an in vitro study. The RET/PTC1 rearrangement was preferentially induced in a dose-dependent manner by X-rays within a high dose range (10, 50 and 100 Gy) in four cell lines. On the other hand, RET/PTC3 was induced at a much lower frequency, and no induction of RET/PTC2 was observed. These results suggest that the preferential induction of the RET/PTC1 rearrangement may play an important role in the early steps of thyroid carcinogenesis induced by acute X-irradiation.

Animals↗
PubMed2000

Amyloid precursor protein in unique cholesterol-rich microdomains different from caveolae-like domains.

To determine the localization of the amyloid precursor protein (APP) on the cellular membrane, we performed membrane fractionation of cultured cells including that of Madin-Darby canine kidney (MDCK) and P19 cells transfected with human APP cDNA, non-transfected SH-SY5Y cells, and rat cerebral cortices. In MDCK cells, APP was exclusively present in abundance in the supernatant following solubilization of the plasma membranes using Triton X-100, and in high-density fractions of sucrose density gradient fractionation (SDGF) following Triton X-100 solubilization of whole cellular membranes. Caveolin-1 was not cofractionated with APP. In experiments using P19 cells and rat cerebral cortices, we detected two isoforms of APP. The APP with the apparently lower molecular weight (immature type) coexisted in abundance with integrin in the high-density fractions, whereas the APP with the apparently higher molecular weight (mature type) was recovered predominantly in the low-density fractions with cholesterol and GM1 gangliosides, the concentrations of which were higher than those in the bulk plasma membranes, but lower than those in caveolae-like domains (CLDs), following SDGF of Triton X-100-solubilized cellular membranes. The results of this study suggest the following; first, APP is not present in abundance in caveolae or CLDs, but is in unique cholesterol-rich microdomains; second, the targeting of APP to these unique microdomains may be linked to the maturation of APP in some cells.

Amyloid beta-Protein Precursor↗
PubMed2000

Activation of basal transcription by a mutation in SIN4, a yeast global repressor, occurs through a mechanism different from activator-mediated transcriptional enhancement.

The Saccharomyces cerevisiae protein Sin4 has been suggested to affect the transcription of various genes by locally altering chromatin structure. Previous studies have defined two classes of promoters: those which are activated by loss of SIN4 function (termed sin4-responsive promoters) and those which are not activated by sin4 mutations (termed sin4 non-responsive promoters). We analyzed the mechanism of this differential response of the two classes of promoters to a sin4 mutation. The sin4 non-responsive promoters were activated when upstream elements in the promoter region were eliminated. The upstream elements of sin4 non-responsive promoters were, in turn, found to repress the activity of the sin4-responsive promoters in an orientation-independent manner. The sin4-mediated activation was repressed by the Rme1- but not by the Tup1-Ssn6-mediated repression system. Activation of sin4-responsive promoters by Pho4 and the sin4 mutation was additive, and enhancement of transcription driven by sin4-responsive promoters was found to be due to an increase in the basal rate of transcription. The upstream regions in the sin4 non-responsive promoters contained elements that were able to inhibit activation of basal transcription. Based on these observations, we suggest that activation of basal transcription by a mutation in a gene for a global repressor, SIN4, occurs through a mechanism that differs from that responsible for activator-mediated transcriptional enhancement, and we therefore propose that basal transcription and activator-mediated transcription are repressed by different mechanisms.

Base Sequence↗
PubMed2000

The Prr1 response regulator is essential for transcription of ste11+ and for sexual development in fission yeast.

Schizosaccharomyces pombe expresses a putative transcription factor, named Prr1, which is intriguing in the sense that it contains a bacterial type of phospho-accepting receiver domain, preceded by a mammalian heat shock factor (HSF2)-like DNA-binding domain. The receiver domain is most probably involved in an as yet unidentified histidine-to-aspartate (His-to-Asp) phosphorelay pathway in S. pombe. In this study, the structure, function, and cellular localization of Prr1 were assessed in the context of oxidative stress and His-to-Asp phosphorelay. As the most intriguing result of this study, we found that Prr1 is essential not only for the expression of genes induced by oxidative stress (e.g., ctt1+ and trr1+), but also for the expression of ste11+, which in turn is responsible for the expression of a variety of genes required for sexual development. Accordingly, Prr1-deficient cells are not only hypersensitive to oxidative stress, but also severely defective in conjugation and/or spore formation. These results suggested that the transcription factor Prr1 plays a pivotal role in an as yet unknown signal transduction pathway that is implicated in sexual differentiation. These findings are discussed with special reference to the well-characterized transcription factors Pap1 and Atf1 of S. pombe.

Activating Transcription Factor 1↗
PubMed2000

Thickened intima of the aortic arch is a risk factor for stroke with coronary artery bypass grafting.

BACKGROUND: Perioperative stroke is one of the most serious complications of cardiac surgery. METHODS: Using transesophageal echocardiography, we estimated the intimal thickness of the thoracic aorta as an index of the severity of aortic atherosclerosis to determine the risk of stroke in coronary artery bypass grafting (CABG) patients. The study population comprised 315 consecutive patients who underwent isolated CABG with cardiopulmonary bypass. RESULTS: Five patients (1.6%) had perioperative cerebral stroke or systemic emboli. We compared the mean intimal thicknesses of the ascending aorta, aortic arch, and descending aorta. Mean thicknesses in patients without stroke were 2.07 +/- 0.76, 2.78 +/- 1.15, and 2.32 +/- 1.21 mm, respectively, and mean thicknesses in the stroke patients were 1.94 +/- 0.55, 6.94 +/- 3.79, and 3.39 +/- 1.85 mm, respectively. The patients with an intima of more than 5 mm at the aortic arch had a significantly greater incidence of perioperative stroke (p = 0.007). CONCLUSIONS: These results suggest that patients who have an aortic arch intima thickened to more than 5 mm are at a significantly high risk for perioperative stroke, and thus, the CABG procedure should be carefully evaluated to prevent such complications.

Aged↗
PubMed2000

Conformation and dynamics of melittin bound to magnetically oriented lipid bilayers by solid-state (31)P and (13)C NMR spectroscopy.

The conformation and dynamics of melittin bound to the dimyristoylphosphatidylcholine (DMPC) bilayer and the magnetic orientation in the lipid bilayer systems were investigated by solid-state (31)P and (13)C NMR spectroscopy. Using (31)P NMR, it was found that melittin-lipid bilayers form magnetically oriented elongated vesicles with the long axis parallel to the magnetic field above the liquid crystalline-gel phase transition temperature (T(m) = 24 degrees C). The conformation, orientation, and dynamics of melittin bound to the membrane were further determined by using this magnetically oriented lipid bilayer system. For this purpose, the (13)C NMR spectra of site-specifically (13)C-labeled melittin bound to the membrane in the static, fast magic angle spinning (MAS) and slow MAS conditions were measured. Subsequently, we analyzed the (13)C chemical shift tensors of carbonyl carbons in the peptide backbone under the conditions where they form an alpha-helix and reorient rapidly about the average helical axis. Finally, it was found that melittin adopts a transmembrane alpha-helix whose average axis is parallel to the bilayer normal. The kink angle between the N- and C-terminal helical rods of melittin in the lipid bilayer is approximately 140 degrees or approximately 160 degrees, which is larger than the value of 120 degrees determined by x-ray diffraction studies. Pore formation was clearly observed below the T(m) in the initial stage of lysis by microscope. This is considered to be caused by the association of melittin molecules in the lipid bilayer.

Amino Acid Sequence↗
PubMed2000

Relationship between indoor and outdoor carbonaceous particulates in roadside households.

Concentrations of particulate matter (PM) and carbonaceous particulates in indoor and outdoor air at roadside private households were measured in Osaka, Japan. The particulate samples were collected on filters using a portable AND sampler capable of separating particles into three different size ranges: over 10 microm, 2-10 microm (coarse) and below 2 microm (fine) in aerodynamic diameter. The filters were weighed and then analyzed for elemental carbon (EC) and organic carbon (OC) by thermal oxidation using a CHN CORDER. The results showed that indoor fine PM concentration is considerably affected by fine EC and the fine EC in indoor air is significantly correlated to that in outdoor air, r=0.86 (n=30, p<0.001). A simple estimation from EC content ratio in diesel exhaust particles indicated that about 30% of indoor particulates of less than 10 microm (PM10) were contributed from diesel exhaust. Additionally, the size characteristics of outdoor PM at roadside and background sites were examined using Andersen Cascade Impactors.

Journal Article↗