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Biomedical subjects

T Miyazaki

Publications and source records attributed to T Miyazaki.

At least 145 records · Page 8Linked to original sources
PubMed2000

Synthesis of regioselectively protected forms of cytidine based on enzyme-catalyzed deacetylation as the key step.

N4-Acetylcytidine (77%) and 2',3'-O, N4-triacetylcytidine (95%) were obtained from the hydrolysis of a common precursor, the peracetylated form of cytidine with Aspergillus niger lipase (Amano A) and Burkholderia cepacia esterase (SC esterase S), respectively, under very mild conditions. The experimental procedure for the conversion of triacetylcytidine to a corresponding phosphoramidite (82%), an intermediate for sugar nucleotide synthesis, is also elaborated.

Acetylation↗
PubMed2000

In vitro and in vivo suppression of osteoclast function by adenovirus vector-induced csk gene.

The proto-oncogene c-src, which encodes a non-receptor-type tyrosine kinase c-Src, has been shown to be essential for osteoclastic bone resorption by the finding that the targeted disruption of the c-src gene induced osteopetrosis in mice. The csk (C-terminal Src family kinase) gene encodes a cytoplasmic protein-tyrosine kinase that specifically phosphorylates the negative regulatory site of c-Src (Tyr-527), thereby inhibiting its kinase activity. To regulate osteoclast function by modulating the kinase activity of c-Src, we constructed an adenovirus vector that carries this gene. The recombinant adenovirus vector carrying csk cDNA induced Csk expression in mouse osteoclast-like cells formed in vitro and clearly reduced c-Src kinase activity in a dose-dependent manner. The expression of Csk caused cytoskeletal disorganization of osteoclast-like cells and strongly suppressed pit-forming activity of the cells in vitro. In addition, the viral vector carrying csk gene dramatically suppressed interleukin-1 alpha-induced bone resorption in vivo. Conversely, kinase-inactive Csk caused an increase in c-Src kinase activity and bone resorbing activity of the cells both in vitro and in vivo, acting as a dominant negative molecule against intrinsic Csk. These findings indicate that the inhibition of c-Src activity by adenovirus vector-mediated csk expression offers an efficient means for inhibiting pathological bone resorption by suppressing osteoclast function.

Adenoviridae↗
PubMed2000

Participation of reactive oxygen species in PGF2alpha-induced apoptosis in rat luteal cells.

Prostaglandin F(2alpha) (PGF(2alpha)) is implicated in the process of luteal regression in many species. Treatment of rat luteal tissue with PGF(2alpha) increases the generation of reactive oxygen species. Since reactive oxygen species have been implicated in apoptosis, the present study was undertaken to determine whether reactive oxygen species play a role in the PGF(2alpha)-induced apoptosis of rat luteal cells. Rat luteal cells were loaded with 6-carboxy-2, 7'-dichlorodihydro-fluorescein (CDCFH) diacetate, di (acetomethyl ester), which can be oxidized by reactive oxygen species to yield CDCF, a fluorescent molecule, and the cells were treated with different doses of PGF(2alpha). Incubation with 100 micromol PGF(2alpha) l(-1) induced an increase in CDCF fluorescence (P < 0. 05). Treatment of cells with PGF(2alpha) for 48 h in serum-free medium induced a dose-dependent increase in cell death, and these cells exhibited the morphological characteristics typical of apoptosis, including condensed or fragmented nuclei and fragmentation of internucleosomal DNA. Pretreatment of these cells with ascorbic acid, N,N'-dimethylthiourea, or superoxide dismutase, which acts as an antioxidant or a radical scavenger, prevented the PGF(2alpha)-induced apoptosis. These results demonstrate that PGF(2alpha) produces reactive oxygen species and induces apoptosis in rat luteal cells, indicating that the reactive oxygen species may induce apoptotic cell death during luteolysis.

Analysis of Variance↗
PubMed2000

Proliferation and differentiation of bone marrow cells on titanium plates treated with a wire-type electrical discharge machine.

For successful dental implants, it is necessary to obtain satisfactory osteointegration at the site of both the cortical and trabecular bones in the jaw. Bone marrow stromal cells differentiate into osteoblast-lineage cells and have an important role in bone remodeling. In this experiment, the responsiveness of bone marrow cells to a titanium plate with a rough surface was compared with that of a titanium plate with a smooth surface. The rough surface was created by treating with a wire-type electrical discharge machine, and the smooth plate was produced by polishing with 1.500-grade emery paper. The results indicated that, though bone marrow cells proliferated on both plates, the proliferation pattern and cell growing time on the plates were different. While the cells on the smooth plate proliferated along the grooves produced by polishing, the cells on the rough plate proliferated randomly and more rapidly. As bone marrow cells consisted of heterogeneous cell populations involving hematopoietic cells, we collected bone marrow mesenchymal stromal cells that proliferated on plastic dishes and studied the proliferation and differentiation of these cells. Stromal cells on the rough plate more actively proliferated than those on the smooth plate. In long-term culture, the cells on the rough plate showed higher alkaline phosphatase activity and produced cell nodules. The cells on the smooth plate were stripped off the plate without nodule formation. These results indicated that bone marrow stromal cells on the rough plate could more rapidly proliferate and differentiate into osteoblast-lineage cells compared with those on the smooth plate.

Animals↗
PubMed2000

Quantitation of macrophage migration inhibitory factor (MIF) using the one-step sandwich enzyme immunosorbent assay: elevated serum MIF concentrations in patients with autoimmune diseases and identification of MIF in erythrocytes.

We raised monoclonal antibodies against human macrophage migration inhibitory factor (MIF), and developed a one-step sandwich enzyme-linked immunosorbent assay (ELISA) method highly specific for human MIF. The ELISA system utilizes a solid phase monoclonal antibody as a capture antibody and a horseradish peroxidase-conjugated monoclonal antibody as a detector antibody. We used this ELISA method to evaluate the serum level of MIF in 240 healthy volunteers (140 males and 100 females). We found no significant difference in MIF concentration with respect to age. A significant difference was found with respect to sex, with the mean value (+/- SD) for male subjects of 5.3+/-2.3, and that for female subjects of 4.6+/-2.3 ng/ml (p<0.05). We next measured the serum MIF contents of patients with autoimmune diseases, and found that MIF levels were significantly elevated in patients with systemic lupus erythematosus and rheumatoid arthritis, 20.0+/-11.0 ng/ml and 21. 7+/-11.2 ng/ml, respectively. Using anti-MIF antibody-immobilized sepharose column chromatography, we discovered for the first time that MIF was present in erythrocytes. Taken together these results suggest that MIF plays a major role in autoimmune diseases and, moreover, potentially induces various patho-logical outcomes in cases of hemolytic disorders.

Adult↗
PubMed2000

Labor reduction for mold preparation of a commercial titanium cast denture system using a heat-shock method.

The purpose of this study was to investigate the application of a heat-shock method to fabricate titanium cast plates. Duplications of a maxillary model were prepared using DM under different firing schedules. Molds with patterns on the duplications were made by an outer investment (D), followed by heat shock at 850 degrees C. Duplications heat shocked at 850 degrees C after 30 min from mixing exploded within a few minutes. This explosion was successfully avoided by a drying procedure prior to the heat-shock. The molds were available for the heat shock at 850 degrees C when the duplicate models were prepared by firing either using the conventional method and the heat shock above method described. Therefore, we could reduce the preparation time from about 16 hr with the conventional method to about 10 hr at the longest with the heat-shock method. These results suggested that the heat-shock method was labor-saving for fabricating titanium cast denture plates when controlling preliminary conditions prior to use.

Dental Casting Investment↗
PubMed2000

Early onset of hemophagocytic syndrome following allogeneic bone marrow transplantation.

We report a 40-year-old man who presented with acute onset of hemophagocytic syndrome (HPS) after allogeneic bone marrow transplantation (alloBMT) for acute myelogenous leukemia. On day 8 after alloBMT, the patient suddenly manifested high-grade fever, transfusion-resistant severe anemia, and thrombocytopenia. Neither veno-occlusive disease nor thrombotic microangiopathy was documented. The level of ferritin in serum was elevated to 1192 ng/mL. A bone marrow aspiration test on day 16 showed a markedly increased number of activated macrophages showing massive hemophagocytosis. Serum levels of interferon-gamma, soluble interleukin-2 receptor, interleukin-6, tumor necrosis factor-alpha, and macrophage colony-stimulating factor (M-CSF) were elevated. From these findings, we determined his transfusion-resistant cytopenias to be attributable to HPS. No viruses (including cytomegalovirus, Epstein-Barr virus, human herpes-virus-6, parvovirus B19, and adenovirus B11) were detected in serum or urine by polymerase chain reaction amplification. We speculate that in addition to the administration of M-CSF, hypercytokinemia during the early phase post-alloBMT might have contributed to the onset of HPS in this patient. Methylprednisolone pulse therapy was very effective for the treatment of the HPS. This case reveals that HPS could develop after alloBMT, even when engraftment of hematopoietic cells is not confirmed.

Adult↗
PubMed2000

The diagnostic value of 123I-IMP SPECT in non-Hodgkin's lymphoma of the central nervous system.

UNLABELLED: N-isopropyl-p-[123I]iodoamphetamine (IMP) SPECT is of low diagnostic value in patients with brain tumors, because brain tumors are visualized as uptake defects. Some reports have described non-Hodgkin's lymphoma of the central nervous system (CNS) as showing high uptake on delayed 123I-IMP SPECT images, suggesting its usefulness in diagnosing CNS lymphoma. In this study, we investigated the clinical value of 123I-IMP SPECT as a diagnostic tool for CNS lymphoma. METHODS: Ninety-six patients with brain tumors, including 12 patients with CNS lymphoma, underwent 123I-IMP SPECT. Eleven patients had primary CNS lymphoma, and 1 had a parenchymal brain metastasis from a breast lymphoma. The total number of lesions was 18, 14 of which were in the cerebral parenchyma, 3 in the brain stem, and 1 in the ventricle. Early SPECT images were initiated 15-30 min after intravenous injection of 111 MBq 123I-IMP, and delayed images were collected 4 h later. SPECT images were visually analyzed with a color-grading scale. Tumor-to-normal activity ratio (T/N) and tumor-to-cerebellum activity ratio (T/C) were calculated for both early and delayed images for semiquantitative analysis. RESULTS: By visual estimation, more than a 3-cm3 volume of CNS lymphoma was detected as an obvious focus of increased accumulation on delayed images. All other brain tumors tested appeared as decreased accumulation on delayed images. T/Ns and T/Cs on delayed images of CNS lymphomas, including tumors less than 3 cm3 in volume, were 1.48+/-0.42 and 1.08+/-0.16, respectively. These ratios in patients with glioma (0.30+/-0.05 and 0.31+/-0.07 respectively) or meningioma (0.34+/-0.10 and 0.41+/-0.17, respectively) showed a significant difference from those in patients with CNS lymphoma (P < 0.0005). CONCLUSION: 123I-IMP SPECT is a helpful tool for diagnosing CNS lymphoma.

Adult↗
PubMed2000

[Relief of subacute herpetic pain and postherpetic neuralgia with repeated application of 10% lidocaine cream].

Analgesic efficacy of repeated application of a lidocaine cream formula was investigated in herpes zoster patients with subacute pain with no further improvement after continued treatment since their acute stage (S-HZ group, n = 23), and in patients to whom past treatments had not provided adequate pain relief (PHN group, n = 28). In both groups, visual analog scale (VAS) values decreased significantly from their corresponding values before the present treatment with few cases of side effects and complete disappearances of the pain in 21.6% of all the patients. The results indicate that the repeated application of the lidocaine cream is a safe and effective treatment method. Significantly higher effectiveness was achieved in the S-HZ group in terms of the difference in the VAS values between before and after the treatment, effectiveness in improving the activities of daily life, and overall efficacy evaluation.

Aged↗
PubMed2000

Human anti-Dia monoclonal antibodies for mass screening.

The use of monoclonal antibodies (mabs) to blood group antigens is constantly increasing for routine typing. Two heterohybridoma cell lines, HMR15 and HMR22, were established by Epstein-Barr virus transformation of peripheral blood lymphocytes from a blood donor with anti-Dia. HMR15 mab directly agglutinated Di(a+) red cells, and HMR22 mab agglutinated Di(a+) red cells exclusively by the indirect antiglobulin test. Reactivities of both HMR15 and HMR22 mabs were specific for Dia and had good correlation with the reactivity of a commercial, polyclonal antiserum. The binding of monoclonal antibodies to antigen-positive red cells was mutually blocked by each other as well as by polyclonal anti-Dia. Immunoprecipitates by HMR22 mab with a Di(a+) preparation showed a 120 kDa band that was stained by anti-band 3. Dia typing of 2427 blood donors with the mabs and polyclonal typing serum detected 244 Di(a+) individuals (10.1%). No discrepancy was observed between the mabs and the polyclonal antiserum. HMR15 and HMR22 mabs are useful Dia typing reagents and can substitute for commercial antiserum.

Journal Article↗
PubMed1999

Functional communications between the apical and equatorial domains of GroEL through the intermediate domain.

The Escherichia coli GroEL subunit consists of three domains with distinct functional roles. To understand the role of each of the three domains, the effects of mutating a single residue in each domain (Y203C at the apical, T89W at the equatorial, and C138W at the intermediate domain) were studied in detail, using three different enzymes (enolase, lactate dehydrogenase, and rhodanese) as refolding substrates. By analyzing the effects of each mutation, a transfer of signals was detected between the apical domain and the equatorial domain. A signal initiated by the equatorial domain triggers the release of polypeptide from the apical domain. This trigger was independent of nucleotide hydrolysis, as demonstrated using an ATPase-deficient mutant, and, also, the conditions for successful release of polypeptide could be modified by a mutation in the apical domain, suggesting that the polypeptide release mechanism of GroEL is governed by chaperonin-target affinities. Interestingly, a reciprocal signal from the apical domain was suggested to occur, which triggered nucleotide hydrolysis in the equatorial domain. This signal was disrupted by a mutation in the intermediate domain to create a novel ternary complex in which GroES and refolding protein are simultaneously bound in a stable ternary complex devoid of ATPase activity. These results point to a multitude of signals which govern the overall chaperonin mechanism.

Adenosine Triphosphate↗
PubMed1999

Structural modification of Fas C-terminal tripeptide and its effects on the inhibitory activity of Fas/FAP-1 binding.

We report the structural requirements of the C-terminal tripeptide derivative of Fas (Ac-Ser-Leu-Val-OH, 1) for the inhibitory activity of Fas/FAP-1 binding. The presence of a carboxyl group and a L-Val residue at the C-terminus is essential for the inhibitory activity, and the hydroxyl group of Ser plays an important role as the donor of a hydrogen bond. The introduction of hydrophobic groups to the N-terminal region of 1, especially the phenylaminocarbonyl group (41), showed a remarkable increase in potency. Further improvement was observed by the attachment of the Glu residue to the meta-position of the phenyl ring of 41 (51). The ester derivative of 41 (56) had the ability to induce apoptosis which was dependent on the concentration of anti-Fas antibody in the colon cancer cell line, DLD-1, which expresses both Fas and FAP-1 and is resistant to Fas-induced apoptosis. We are now investigating whether FAP-1 is a main target of 56 and whether the inhibition of Fas/FAP-1 binding by 56 retrieves the apoptotic signal.

Antibodies↗
PubMed1999

Gill lamellar pillar cell necrosis, a new birnavirus disease in Japanese eels.

Since the late 1980s, a birnaviral gill disease has been occurring in Japanese eels Anguilla japonica reared in warmwater ponds in western regions in Japan. Diseased eels mostly displayed marked formations of aneurysmal hematomas within gill lamellae and high mortalities. Histological examination revealed necrosis of pillar cells and subsequent aggregation of erythrocytes inside the lamellar capillaries, and proliferation of interlamellar epithelia onto the lamellae. Gastric gland cells were also necrotized. Electron microscopy revealed birnavirus infection in lamellar pillar cells. The causative birnavirus was isolated and cultured in fish cell lines and was found to be related to an infectious pancreatic necrosis virus (IPNV) Sp serotype by neutralization tests. The viral pathogenicity was confirmed by the results of histopathological examinations and infectivity experiments.

Anguilla↗
PubMed1999

Protein tyrosine kinase Pyk2 mediates the Jak-dependent activation of MAPK and Stat1 in IFN-gamma, but not IFN-alpha, signaling.

Two distinct types of interferon, IFN-alpha/beta and IFN-gamma, commonly exhibit antiviral activities by transmitting signals to the interior of the cell via their homologous receptors. Receptor stimulation results in the activation of distinct combinations of Janus family protein tyrosine kinases (Jak PTKs); Jak1/Tyk2 and Jak1/Jak2 for IFN-alpha/beta and IFN-gamma, respectively. Jak PTK activation by these IFNs is commonly followed by tyrosine phosphorylation of the transcription factor Stat1 at Y701, which is essential for dimerization, translocation to the nucleus and DNA-binding activity. To gain full transcriptional activity, Stat1 also requires serine phosphorylation at S727. In this paper we demonstrate that Pyk2, which belongs to another PTK family, is critical for the Jak-mediated MAPK and Stat1 activation by IFN-gamma, but not IFN-alpha. Pyk2 is selectively associated with Jak2 and activated by IFN-gamma. Overexpression of PKM, a dominant interfering form of Pyk2, in NIH 3T3 cells results in a strong inhibition of the IFN-gamma-induced activation of Erk2, serine phosphorylation of Stat1 and Stat1-dependent gene transcription. Finally, the antiviral action of IFN-gamma, but not IFN-alpha, is severely impaired by PKM overexpression. Thus, the two types of IFN may utilize distinct Jak-mediated Erk2, and possibly other MAPK activation pathways for their antiviral action.

3T3 Cells↗
PubMed1999

Role of interleukin (IL)-2 receptor beta-chain subdomains and Shc in p38 mitogen-activated protein (MAP) kinase and p54 MAP kinase (stress-activated protein Kinase/c-Jun N-terminal kinase) activation. IL-2-driven proliferation is independent of p38 and p54 MAP kinase activation.

We have shown recently that interleukin (IL)-2 activates the mitogen-activated protein (MAP) kinase family members p38 (HOG1/stress-activated protein kinase II) and p54 (c-Jun N-terminal kinase/stress-activated protein kinase I). Furthermore, the p38 MAP kinase inhibitor SB203580 inhibited IL-2-driven T cell proliferation, suggesting that p38 MAP kinase might be involved in mediating proliferative signals. In this study, using transfected BA/F3 cell lines, it is shown that both the acidic domain and the membrane-proximal serine-rich region of the IL-2Rbeta chain are required for p38 and p54 MAP kinase activation and that, as for p42/44 MAP kinase, this activation requires the Tyr338 residue of the acidic domain, the binding site for Shc. It is well established that the acidic domain of the IL-2Rbeta chain is dispensable for IL-2-driven proliferation, and thus our observations suggest that neither p38 nor p54 MAP kinase activation is required for IL-2-driven proliferation of BA/F3 cells. In addition, the tetravalent guanylhydrazone inhibitor of proinflammatory cytokine production, CNI-1493, can block the activation of p54 and p38 MAP kinases by IL-2 but has no effect on IL-2-driven proliferation of BA/F3 cells, activated primary T cells, or a cytotoxic T cell line. Furthermore, our observations provide evidence for the existence of an additional, unknown target of the p38 MAP kinase inhibitor SB203580, the activation of which is essential for mitogenic signaling by IL-2.

Animals↗