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Biomedical subjects

Y Shibata

Publications and source records attributed to Y Shibata.

At least 145 records · Page 8Linked to original sources
PubMed1999

Synthesis and antimalarial activity of cyclic peroxides, 1,2,4,5, 7-pentoxocanes and 1,2,4,5-tetroxanes.

A variety of 1,2,4,5,7-pentoxocane and 1,2,4,5-tetroxane derivatives were prepared as potential peroxide antimalarial agents. In both series of cyclic peroxides, the steric and electronic effects of the substituents attached to the peroxide ring exert a remarkable influence on the antimalarial activity. For some cyclic peroxides, which were found to be highly effective in vitro, the study in vivo has been also conducted.

Animals↗
PubMed1999

A new boronated porphyrin (STA-BX909) for neutron capture therapy: an in vitro survival assay and in vivo tissue uptake study.

A new boronated porphyrin compound (STA-BX909) was developed as a possible agent for boron neutron capture therapy. The boron concentration was measured by an in vivo rat experimental brain tumor model and an in vitro cell culture study. This agent was compared to sodium borocaptate (BSH) which has been used in clinical trials of boron neutron capture therapy. In the 9L rat brain tumor model, STA-BX909 achieved a higher boron tumor/blood ratio 24 h after injection in comparison to BSH. A boron concentration study in cultured glioma cell lines (U-251, U-87, 9L) demonstrated an increased boron concentration as a function of exposure time to STA-BX909, while the boron concentration remained stable with increasing exposure time to BSH. Use of a colony forming assay with thermal neutron irradiation revealed more cytotoxicity with STA-BX909 than BSH when the same concentration of 10B was administered. We concluded that STA-BX909 may be an effective drug for use in boron neutron capture therapy and that it merits further investigation.

Animals↗
PubMed1999

Induction of differentiation of pre-NKT cells to mature Valpha14 NKT cells by granulocyte/macrophage colony-stimulating factor.

Valpha14 NKT cells express an invariant antigen receptor encoded by Valpha14 and Jalpha281 gene segments as well as natural killer (NK) markers, including NK1.1. Here, we describe a precursor population of NKT cells (pre-NKT) that expresses NK1.1, T cell antigen receptor beta, pTalpha, and RAG1/2 but not Valpha14 and surface CD3epsilon. Such pre-NKT cells were differentiated successfully in vitro into mature CD3epsilon+ Valpha14(+) NKT cells by IL-15 and granulocyte/macrophage colony-stimulating factor (GM-CSF) in conjunction with stroma cells. Interestingly, only GM-CSF without stroma cells induced the Valpha14-Jalpha281 gene rearrangement in the pre-NKT cells. This also was confirmed by the findings that the number of mature Valpha14 NKT cells and the frequency of Valpha14-Jalpha281 rearrangements were decreased significantly in the mice lacking a GM-CSF receptor component, common beta-chain. These results suggest a crucial role of GM-CSF in the development of Valpha14 NKT cells in vivo.

Animals↗
PubMed1999

A novel dnaK operon from Porphyromonas gingivalis.

The nucleotide sequence of the dnaK operon cloned from Porphyromonas gingivalis revealed that the operon does not contain homologues of either dnaJ or grpE. However, there were two genes which encode small heat shock proteins immediately downstream from the dnaK and they were transcribed together with dnaK as one unit. The ATPase activity of the P. gingivalis DnaK was synergistically stimulated up to 40-fold in the simultaneous presence of Escherichia coli DnaJ and GrpE. These results suggest that the DnaK homologue of P. gingivalis, with its unique genetic structure and evolutionary features, works as a member of the DnaK chaperone system.

Adenosine Triphosphatases↗
PubMed1999

Determination and characterization of the hemagglutinin-associated short motifs found in Porphyromonas gingivalis multiple gene products.

Porphyromonas gingivalis is a Gram-negative anaerobic bacterial species implicated as an important pathogen in the development of adult periodontitis. In our studies of P. gingivalis and ways to protect against periodontal disease, we have prepared the monoclonal antibody mAb-Pg-vc and its recombinant antibody, which are capable of inhibiting the hemagglutinating activity of P. gingivalis (Shibata, Y., Kurihara, K., Takiguchi, H., and Abiko, Y. (1998) Infect. Immun. 66, 2207-2212). To clarify the antigenically related hemagglutinating domains, we attempted to determine the minimum motifs responsible for P. gingivalis hemagglutinin. Initially, the 9-kilobase EcoRI fragment encoding the 130-kDa protein was cloned from the P. gingivalis chromosome using mAb-Pg-vc. Western blot analysis of nested deletion clones, the competition experiments using synthetic peptides, and the binding assay of the phage-displayed peptides using the mAb-Pg-vc allowed us to identify the minimum motifs, PVQNLT. Furthermore, the presence of multi-gene family coding for this epitope was confirmed via Southern blot analysis and PCR using the primers complementary to the domain corresponding to this epitope. It is suggested that the hemagglutinin-associated motif may be PVQNLT and that the gene families specifying this motif found in P. gingivalis chromosome encode many hemagglutinin and/or hemagglutinin-related proteases.

Adhesins, Bacterial↗
PubMed1999

Conformational fluctuation of native-like and molten-globule-like cytochrome c observed by time-resolved hole burning.

Nanosecond to millisecond conformational fluctuations of Zn-substituted cytochrome c (ZnCytc) have been studied by the time-resolved transient hole-burning method. The investigation of low-temperature dynamics has been made on the ZnCytc solution sample in a water-glycerol mixture. The conformational fluctuations in the native-like and the molten-globule (MG)-like states have been compared for the aqueous solution samples at room temperature. ZnCytc in the MG-like state has been prepared by adding 200 mM NaClO4 to the protein solution with a pH of 2.1, and the formation of the MG-like state has been confirmed by both the far-UV CD and the visible absorption spectra. The hole spectrum of ZnCytc has been found to consist of two nearly degenerate components, that is, the Qx and Qy bands. The temporal change in the Qx component hole spectrum has been extracted by fitting the observed hole spectrum to the three-Gaussian form. The experimental results for ZnCytc dissolved in a water-glycerol mixture have revealed that the conformational fluctuation of ZnCytc is suppressed around 200 K, which is nearly the same temperature as the glass-like transition point of Zn-substituted myoglobin (ZnMb) and also as the glass-transition point of the solvent. This supports the idea of the solvent-induced glass-like transition of a protein. It has been also found that at physiological temperatures the time scale of the conformational fluctuation of ZnCytc lies around a few tens of nanoseconds, which is 2-3 orders of magnitude faster than that of ZnMb. The experimental results for the aqueous solution samples have shown that the difference between the native-like and the MG-like states is not conspicuous. However, they are indicative of the appearance of the slower conformational fluctuation in the MG-like state.

Animals↗
PubMed1999

Solvent effects on conformational dynamics of Zn-substituted myoglobin observed by time-resolved hole-burning spectroscopy.

Equilibrium conformational fluctuation of Zn-substituted myoglobin (ZnMb) has been studied in the nanosecond to millisecond time region and 180-300 K temperature region by the time-resolved transient hole-burning spectroscopy. In this technique, the conformational fluctuation of the protein is observed as the temporal variation of the hole spectrum burned by irradiation of the laser pulse. ZnMb solution samples in various solvent conditions were prepared and investigated to elucidate the solvent effect on the conformational dynamics of Mb. The configuration coordinate model assuming the harmonic energy landscape has given a fairly good description of the time dependence of the hole spectra. The observed temporal behavior of both the hole shift and the hole broadening was well expressed by the same stretched exponential correlation function with a rather small and almost temperature-independent beta of 0.26. It was found that the correlation time tauc of the conformational fluctuation of ZnMb determined by this analysis depends linearly on the solvent viscosity regardless of the solvent composition and temperature. This means the almost 0 activation energy for the fluctuation process and can not be understood by simply assuming the Arrhenius-type crossing of the barriers separating the conformational substates. It is shown that this linear viscosity dependence of tauc, as well as the temperature-independent beta, is qualitatively explained in the framework of the hierarchically constrained dynamics (HCD) model [Palmer, R. G. et al. (1984) Phys. Rev. Lett. 53, 958-961] with the postulate that the dynamics in the lowest level in the HCD model corresponds in the actual system to the configuration fluctuations of the solvent molecules surrounding the protein.

Models, Chemical↗
PubMed1999

Studies on fertilization in the teleost. III. The relationship between nuclear behavior and the histone H1 kinase activity in anesthetized medaka eggs

To investigate the mechanisms of fertilization in the teleostean egg, the relationship between the nuclear behavior and the activity of histone H1 kinase was examined in medaka, Oryzias latipes, eggs that were anesthetized at sperm penetration. Inseminated in the anesthetized state, most eggs failed to undergo the propagative waves of increase in cytoplasmic Ca(2+) and exocytosis of cortical alveoli (CABD). The sperm-penetrated eggs that exhibited no or partial CABD only around the animal pole underwent a transient contraction of the cortical cytoplasm toward the animal pole region and were designated nonactivated eggs. Temporary compaction of the second meiotic metaphase (MII) chromosomes was accompanied by contractile movement of the cortical cytoplasm, but not by completion of the second meiotic division. The activity of histone H1 kinase in nonactivated eggs remained high, although it decreased slightly concurrent with sperm penetration. Cyclin B and cdc2 levels remained unchanged as well. The nonactivated eggs began to transform the penetrated sperm nucleus into metaphase chromosomes in the cortical cytoplasm facing the inner end of micropylar canal within 20 min postinsemination (PI). Two figures of typical metaphase chromosomes were found in the animal pole area at </=40 min PI. Chromosome condensation in nonactivated eggs was not inhibited by actinomycin D, nor was the high activity of histone H1 kinase reduced. In the presence of cycloheximide or 6-dimethylaminopurine (6-DMAP), however, the compact sperm nucleus and the MII chromosomes transformed to interphase nuclei without CABD or extrusion of the polar body, although the activity of histone H1 kinase remained high. These results suggest that in the fish egg, transformation of MII chromosomes to an interphase nucleus may not be caused by loss of MPF activity, but rather than by the loss of activity of a short-lived protein kinase(s), sensitive to 6-DMAP that is independent of CABD in the cascade reactions triggered by increased cytoplasmic calcium. Copyright 1999 Wiley-Liss, Inc.

Journal Article↗
PubMed1999

Functional expression of beta1 and beta2 integrins on tumor infiltrating lymphocytes (TILs) in colorectal cancer.

Integrins play an important role in various lymphocyte functions. In this study, tumor-infiltrating lymphocytes (TIL) were isolated from colorectal cancer tissues and the expression of beta1 and beta2 integrins on the TIL was quantitatively examined with two-color flow cytometry. In comparison with peripheral blood lymphocytes (PBL), TIL expressed a lower level of common beta1 chain (CD29) in both CD4 and CD8 subpopulations. Among the associated alpha chains, the expressions of alpha1 (CD49a) and alpha2 (CD49b) were slightly higher in TIL than in PBL, whereas alpha4 (CD49d) and alpha6 (CD49f) were markedly downregulated in TIL. Both alphaL (CD11a) and beta2 (CD18) were reduced in CD8(+) TIL but not in CD4(+) TIL. TIL with the CD8(+) cytotoxic phenotype showed significantly decreased binding to purified intracellular adhesion molecules (ICAM)-1, and vascular adhesion cell molecule (VCAM)-1, and HT29 colon cancer cells, compared with the in counterparts in PBL. The peculiar expression pattern and functional down regulation of these integrins may explain why TIL in colorectal cancer cannot eradicate the malignant cells.

Aged↗
PubMed1999

The use of an external-internal shunt in the treatment of extracranial internal carotid artery saccular aneurysms: technical case report.

BACKGROUND: Extracranial internal carotid artery aneurysms (EICAA) are rare lesions. Resection and grafting is the preferred method of management. However, the details of shunt use in surgery for this type of aneurysm has been described in few articles. We describe an external-internal shunt with intra-aneurysmal trans-orifice insertion. CASE REPORT: A 55-year-old woman presented with a 5-year history of a progressively enlarging pulsatile neck mass. An examination revealed no neurological deficit. Right carotid angiogram showed a saccular EICAA involving the ICA distal to the bifurcation, with kinking of the internal carotid artery (ICA). The dome of the EICAA extended from the upper border of C4 to the midportion of C2 and the maximum diameter was 4 cm. RESULTS: Using the shunt technique, we successfully removed the aneurysm and reconstructed the ICA. The end-to-end anastomosis was easy because the shunt was involved only in the distal free end of the ICA, but not in the proximal free end of the ICA. CONCLUSION: This technique could be an option for the treatment of EICCA when a shunt is needed to maintain the cerebral circulation.

Anastomosis, Surgical↗
PubMed1999

Claudin-1 contributes to the epithelial barrier function in MDCK cells.

Tight junctions (TJs) create a paracellular permeability barrier and also act as a fence preventing intermixing of proteins and lipids between the apical and basolateral plasma membranes. Recently, claudin-1 has been identified as an integral membrane protein localizing at TJs, and introduced claudin-1 can form TJ-like networks in fibroblasts. To investigate the function of claudin-1, MDCK cells were transfected with a mammalian expression vector containing myc-tagged mouse claudin-1, and four stable clones were obtained. The myc-tagged claudin-1 precisely colocalized with both occludin and ZO-1 at cell-cell contact sites, indicating that exogenous claudin-1 was properly targeted to the TJs. Immunoblot analysis revealed that overexpression of claudin-1 increased expression of ZO-1 but not of occludin or ZO-2. The barrier functions of these cells were evaluated by transepithelial electrical resistance (TER) and paracellular flux. Claudin-1-expressing cells exhibited about four times higher TER than wild-type MDCK cells. Consistent with the increase of TER, the cells overexpressing claudin-1 showed reduced paracellular flux, estimated at 4 and 40 kD FITC-dextrans. These results suggest that claudin-1 is involved in the barrier function at TJs.

Animals↗
PubMed1999

Analysis of factors related to jugular venous oxygen saturation during cardiopulmonary bypass.

OBJECTIVE: To investigate preoperative clinical conditions and/or intraoperative physiologic variables related to jugular venous oxygen saturation (SjO2) during cardiopulmonary bypass (CPB). DESIGN: Prospective study. SETTING: General hospital, single institution. PARTICIPANTS: One hundred forty patients (52 women, 88 men) who underwent coronary artery bypass grafting. MEASUREMENTS AND MAIN RESULTS: The authors measured SjO2 at five times during surgery. Multiple stepwise regression analysis showed a significant correlation of SjO2 with (1) arterial carbon dioxide partial pressure (PaCO2) before CPB (standard regression coefficient [(SC)] = 0.435), (2) cerebral perfusion pressure (CPP) during initiation of CPB (SC = 0.259), (3) PaCO2, tympanic temperature (TT), bubble oxygenator, and cerebral small infarctions (CSIs) during hypothermic CPB (SC = 0.507, -0.237, -0.192, and -0.189, respectively), (4) CPP, PaCO2, CSIs, and bubble oxygenator during rewarming (SC = 0.476, 0.294, -0.220, and -0.189, respectively), and (5) PaCO2 after CPB (SC = 0.480; p < 0.01). Correlation coefficients between SjO2 and CPP during rewarming were 0.40 (0.46 without CSI and 0.37 with CSI; p < 0.01). These results indicate that the relationship between CPP and SjO2 was significant in patients with CPP less than 40 mmHg during rewarming. CONCLUSION: During rewarming, when cerebral perfusion and oxygen demand change abruptly, but not during stable hypothermic CPB, CPP was a significant factor related to sjO2.

Aged↗
PubMed1999

Isolation and characterization of the rml gene homologs from Porphyromonas gingivalis.

We cloned four genes from the Porphyromonas gingivalis chromosome, the gene products of which catalyze the anabolism of dTDP-L-rhamnose from D-glucose-1-phosphate when they were expressed in Escherichia coli. The amino acid sequences deduced from these genes showed significant homology to proteins encoded by the rml genes involved in dTDP-L-rhamnose biosynthesis in other gram-negative bacteria. Reverse transcriptase polymerase chain reaction analysis revealed that these four genes are expressed as a single transcript in P. gingivalis. To clarify the role of the rml gene homologs in this organism, construction of mutants defective in the rml gene homologs was attempted by allelic exchange. Unexpectedly, any mutants defective in the rml gene homologs were unable to be isolated, and the allelic exchange was possible only if the wild-type rml gene homologs were present on the chromosome. These results suggest that the rml gene homologs might be essential for the viability of P. gingivalis under the culture conditions used in this study.

Bacterial Proteins↗
PubMed1999

Inhibition of haematogenous metastasis of colon cancer in mice by a selective COX-2 inhibitor, JTE-522.

It is proposed that non-steroidal anti-inflammatory drugs (NSAIDs) reduce colorectal tumorigenesis by inhibition of cyclooxygenase (COX). COX is a key enzyme in the conversion of arachidonic acid to prostaglandins and two isoforms of COX have been characterized, COX-1 and COX-2. Multiple studies have shown that COX-2 is expressed at high levels in colorectal tumours and play a role in colorectal tumorigenesis. Recently it has been reported that selective inhibition of COX-2 inhibits colon cancer cell growth. In this study we investigated the effect of a selective COX-2 inhibitor (JTE-522) on haematogenous metastasis of colon cancer. For this purpose, we selected a murine colon cancer cell line, colon-26, that constitutively expresses the COX-2 protein. The subclone P expressed a high level of COX-2 and the subclone 5 expressed a low level. The colon-26 subclones were injected into the tail vein of BALB/c mice. JTE-522 was given intraperitoneally every day from the day prior to cancer cell injection, and the mice were sacrificed 16 days after cell injection. Lung metastases were compared between groups with and without JTE-522. In the mice injected with subclone P, the number of lung metastatic nodules was significantly reduced in the treated group. However, in the mice injected with subclone 5, there was little difference between the control and the treated groups. These results indicate that there may be a direct link between inhibition of haematogenous metastasis of colon cancer and selective inhibition of COX-2, and that selective COX-2 inhibitors may be a novel class of therapeutic agents not only for colorectal tumorigenesis but also for haematogenous metastasis of colon cancer.

Animals↗
PubMed1999

Polymorphisms of HLA-DM genes in Japanese patients with psoriasis vulgaris.

We analysed the polymorphisms of HLA-DM genes in 85 unrelated Japanese patients with psoriasis vulgaris and 52 healthy controls using the polymerase chain reaction-restriction fragment length polymorphism method. The frequency of DMA*0101 was decreased (79% vs. 89%, P < 0.05) and that of DMA*0102 was increased (20% vs. 11%, P < 0.05) in the patients. However, neither of these remained significant after P-values were corrected for the number of comparisons made (Pc > 0.05). As we reported previously, HLA-C molecules are assumed to play a more important part than HLA-DM genes in the development of psoriasis vulgaris.

Adult↗
PubMed1999

Abnormalities of developmental cell death in Dad1-deficient mice.

BACKGROUND: Dad1, the defender against apoptotic cell death, comprises the oligosaccharyltransferase complex and is well conserved among eukaryotes. In hamster BHK21-derived tsBN7 cells, loss of Dad1 causes apoptosis which cannot be prevented by Bcl-2. RESULTS: To determine the role of Dad1 function in vivo, we prepared by gene targeting, mice harbouring a disrupted Dad1 gene. Homozygous mutants died shortly after they were implanted with the characteristic features of apoptosis. In an in vitro blastocyst culture system, Dad1-null cells displayed abnormalities which were comparable to those obtained in vivo. However, oligosaccharyltransferase activity was apparently retained even after the Dad1-null cells were destined to die. Some live-born heterozygous mutants displayed soft-tissue syndactyly. Mild thymic hypoplasia was also indicated in heterozygotes. CONCLUSION: These results suggest the involvement of the Dad1 gene in the acquisition of a common syndactyly phenotype, as well as in the control of programmed cell death during development.

Animals↗
PubMed1999

Studies on fertilization of the teleost. II. Nuclear behavior and changes in histone H1 kinase.

In order to understand the dynamic responses of gamete nuclei upon fertilization in the fish, Oryzias latipes, the relationship between changes in the activity of histone H1 kinase and nuclear behavior was examined during fertilization. Kinase activity rapidly decreased concomitant with the initiation of the propagative exocytosis of cortical alveoli following sperm attachment to the egg plasma membrane post-insemination (PI). Activity again increased 30 min PI. Similar changes in kinase activity, migration and syngamy of pronuclei, and subsequent cleavage were observed with aphidicolin or actinomycin D treatment, except that formation of abnormal metaphase chromosomes was retarded in aphidicolin-treated zygotes. Pretreatment of unfertilized eggs with cycloheximide or 6-dimethylaminopurine (6-DMAP) caused no nuclear changes. The activity of histone H1 kinase in these eggs rapidly declined following sperm penetration and exocytosis, but did not undergo subsequent increase in the presence of these inhibitors. In these eggs with low histone H1 kinase activity, the fertilization process from sperm penetration to syngamy occurred normally, but the pronuclear membrane did not break down and the chromosomes did not condense. The present data suggest that in fish eggs, DNA replication as well as the synthesis and phosphorylation of proteins, especially cyclin B, are required for normal formation of metaphase chromosomes at the first cleavage, but not for fertilization events from sperm penetration through to nuclear migration resulting in syngamy.

Adenine↗