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Biomedical subjects

K Miyazawa

Publications and source records attributed to K Miyazawa.

At least 73 records · Page 4Linked to original sources
PubMed1999

Formation process of autophagosome is traced with Apg8/Aut7p in yeast.

We characterized Apg8/Aut7p essential for autophagy in yeast. Apg8p was transcriptionally upregulated in response to starvation and mostly existed as a protein bound to membrane under both growing and starvation conditions. Immunofluorescence microscopy revealed that the intracellular localization of Apg8p changed drastically after shift to starvation. Apg8p resided on unidentified tiny dot structures dispersed in the cytoplasm at growing phase. During starvation, it was localized on large punctate structures, some of which were confirmed to be autophagosomes and autophagic bodies by immuno-EM. Besides these structures, we found that Apg8p was enriched on isolation membranes and in electron less-dense regions, which should contain Apg8p-localized membrane- or lipid-containing structures. These structures would represent intermediate structures during autophagosome formation. Here, we also showed that microtubule does not play an essential role in the autophagy in yeast. The result does not match with the previously proposed role of Apg8/Aut7p, delivery of autophagosome to the vacuole along microtubule. Moreover, it is revealed that autophagosome formation is severely impaired in the apg8 null mutant. Apg8p would play an important role in the autophagosome formation.

Autophagy-Related Protein 8 Family↗
PubMed1999

Development of in vitro matured and fertilized bovine embryos cocultured with bovine oviductal epithelial cells obtained from oviducts ipsilateral to cystic follicles.

The present experiment was conducted to clarify the effect of bovine oviductal epithelial cells (BOEC) collected from oviducts ipsilateral to cystic follicles (CFs) using an in vitro coculture system on the development of in vitro matured/fertilized (IVM/IVF) bovine embryos. In the first comparison, the effect of the presence of CF on the development of the embryos cocultured with BOEC derived from the cows with CF (n = 18) and corpus hemorrhagicum (CH, n = 10) was examined. In the second comparison, the effect of the type of cyst [progesterone (P4)-dominant; n = 9, estradiol-17beta (E2)-dominant; n = 5] on the development of the embryos cocultured with BOEC derived from the cystic cows was examined. No difference was observed between CF and CH (control) groups in the mean developmental rates of embryos developed to > or =2-cell (86.3% vs. 86.4%), 8-16 cells (53.0% vs. 56.2%), blastocyst (24.2% vs. 24.8%) and hatched blastocyst (12.0% vs. 14.6%). However, the blastocyst production rate was significantly different (P<0.05) between the P4-dominant (19.8%) and E2-dominant (32.6%) groups. The rate of development from cleavage stage embryo to blastocyst was significantly different between P4-dominant (22.9%) and E2-dominant (37.9%) groups. Moreover, the blastocyst rate from 8-16 cells of E2-dominant group (61.6%) was significantly higher than that of P4-dominant one (39.5%). These results indicate that the effects of BOEC collected from oviduct ipsilateral to CFs on embryo development are variable, and the variability is closely associated with the steroid hormone profiles of the follicular fluid.

Animals↗
PubMed1999

Infectivity of feline enteroepithelial stages of Toxoplasma gondii isolated by Percoll-density gradient centrifugation.

The infectivity of the feline enteroepithelial stages of Toxoplasma gondii isolated by Percoll-density gradient centrifugation was examined by the trypan blue dye exclusion method by assaying their penetration into feline fibroblast cells in vitro and by inoculation of the intestinal mucosa of cats. A large population of the parasites showed trypan blue dye exclusion activity. When feline fibroblast cells were inoculated with feline enteroepithelial stage parasites, no intracellular parasites were found 18 h post-inoculation. Kittens inoculated intraduodenally with 2 x 10(6) feline enteroepithelial stage parasites shed oocysts between 2 and 8 days post-inoculation. These results indicate that the isolated feline enteroepithelial stage parasites display infectivity towards enterocytes of cats and are capable of gametogenesis.

Animals↗
PubMed1999

Etidronate (EHDP) inhibits osteoclastic-bone resorption, promotes apoptosis and disrupts actin rings in isolate-mature osteoclasts.

Bisphosphonates, therapeutic reagents against tumoral bone diseases (Paget's disease or osteoporosis), are potent inhibitors of bone resorption. The mechanisms by which they directly act on mature osteoclasts remain unclear. Using a recently developed technique for isolation of highly purified mammalian mature osteoclasts, we demonstrated that etidronate [ethane-1-hydroxy-1,1-diphosphonate (EHDP), 1-hydroxy-1,1-ethylidenebisphosphonate], inhibited directly osteoclastic bone-resorbing activity by pit assay. In addition, EHDP also directly induced apoptosis and disrupted actin rings in osteoclasts. The data support previous data on non-purified osteoclasts and results in vivo.

Actins↗
PubMed1999

Ultrastructural characteristics of Babesia caballi in equine erythrocytes in vitro.

Babesia caballi cultured continuously in equine erythrocytes was examined by transmission electron microscopy. The use of cultured B. caballi permitted examination of a large number of parasitized cells with various stages of intra erythrocytic development. The piriform merozoites of B. caballi were composed of an outer membrane and an inner double-membrane complex. Numerous micronemes and three rhoptries were found in the pellicle of the merozoite, and a spherical body was seen in the anterior part of the merozoite which usually lay adjacent to the nucleus and the pellicle. These findings were similar to those for merozoites of bovine Babesia parasites such as B. bigemina. The trophozoites were surrounded by a single membrane, were continuously changing their body shape with extension and retraction of the pseudopod. A long pseudopod extended far into the host cell cytoplasm, and was finally completely enclosed in a cell, but did not have hemozoin pigment, the breakdown product of hemoglobin digestion.

Animals↗
PubMed1999

A fibrinolytic enzyme from a marine green alga, Codium latum.

A fibrinolytic enzyme was isolated from a marine green alga, Codium latum, and designated C. latum protease (CLP). It also had fibrinogenolytic activity, hydrolyzing A alpha, B beta and gamma chains with preference in this order. As CLP hydrolyzed oxidized insulin B chain at position Arg22-Gly23, and the peptide map of lysozyme digested with CLP was similar to that with trypsin, CLP would be expected to have a high substrate specificity, similar to that of trypsin. Protease activity peaked at pH 10, and was completely inhibited by diisopropyl fluorophosphate (DFP). Therefore, we conclude that CLP is a trypsin-like serine protease.

Animals↗
PubMed1999

IL-6 synthesis by rheumatoid synoviocytes is autonomously upregulated at the transcriptional level.

BACKGROUND: Involvement of IL-6 in the pathogenesis of rheumatoid arthritis has recently been demonstrated, but the mechanism of its production by rheumatoid synoviocytes is still poorly defined. OBJECTIVE: The purpose of this study was to clarify the cellular and molecular mechanisms involved in the spontaneous production of IL-6 by fibroblast-like synoviocytes obtained from patients with rheumatoid arthritis. METHODS: Cloned synoviocytes were established by the limiting dilution method. IL-6 synthesis was evaluated by ELISA and Northern blot analysis. IL-6 gene transcription and transcription factors were analyzed by the transient transfection of luciferase reporter plasmids and the electrophoretic mobility shift assay, respectively. RESULTS: IL-6 synthesis by cloned rheumatoid synoviocytes was spontaneously upregulated at the transcriptional level. Enhanced IL-6 production by high-producing clones was independent of cytokines from other cell populations or autocrine production of tumor necrosis factor-alpha and IL-1. Deletion analysis showed that the IL-6 promoter was regulated by 2 positive elements (-159 to -142 base pair and -77 to -59 base pair). The transcriptional activity of the latter element was upregulated in clones showing high IL-6 production. The binding activity of NF-kappaB p50/p65 heterodimer and RBP-Jkappa was enhanced in these clones. CONCLUSION: IL-6 production by rheumatoid synoviocytes is autonomously upregulated at the transcriptional level and spontaneous activation of NF-kappaB and RBP-Jkappa seems to be involved.

Arthritis, Rheumatoid↗
PubMed1999

Vitamin K2 induces apoptosis of a novel cell line established from a patient with myelodysplastic syndrome in blastic transformation.

We have previously reported that vitamin K2 (VK2) has a potent apoptosis inducing activity toward various types of primary cultured leukemia cells including acute myelogenous leukemia arising from myelodysplastic syndromes (MDS). We established a novel cell line, designated MDS-KZ, from a patient with MDS in blastic transformation, and further investigated the effects of VK2 using this novel cell line. MDS-KZ shows complex chromosomal anomaly including -4, 5q-, -7, 13q+, 20q-, consistent with that seen in the original patient. Culture of MDS-KZ cells in RPMI1640 medium containing 10% FBS lead to steady but very slow proliferation with a doubling time of 14 days. However, the cellular growth rate was significantly accelerated in the presence of various growth factors such as granulocyte colony-stimulating factor, stem cell factor, granulocyte-macrophage colony-stimulating factor, interleukin-3, and thrombopoietin. Most of the cultured cells show the morphological features of myeloblasts. They are positive for CD7, CD33, CD34, CD45, CD117, and HLA-DR. However, about 10% of the cells are more mature metamyelocytes and neutrophils with various dysplastic characteristics such as pseudo-Pelger nuclear anomaly and hypersegmentation, suggesting a potential for differentiation in this cell line. As previously reported for cultured primary leukemia cells, exposure to VK2, but not to VK1, resulted in induction of apoptosis of MDS-KZ cells in a dose-dependent manner (IC50: 5 microM). In addition, VK2 treatment induced down-regulation of BCL-2 and up-regulation of BAX protein expression with concomitant activation of caspase-3 (CPP32). A tetrapeptide functioning as antagonist of caspase-3, Ac-DEVD-H, suppressed the VK2-induced inhibition of cell growth, suggesting that caspase-3 is, at least in part, involved in VK2-induced apoptosis. These observations suggest that the MDS-KZ cell line can serve as a model for the study of the molecular mechanisms of VK2-induced apoptosis.

Aged↗
PubMed1999

SDF-1 suppresses cytokine-induced adhesion of human haemopoietic progenitor cells to immobilized fibronectin.

The process of haemopoietic cell homing to the microenvironment includes migration and adhesion. SDF-1 is a C-X-C chemokine that acts as a chemoattractant for haemopoietic progenitors. Adhesion of haemopoietic progenitors to immobilized fibronectin is up-regulated by stimulation with cytokines. We assessed the effects of SDF-1 on cytokine-induced adhesion of progenitor cells to fibronectin. In factor-dependent human MO7e cells and primary CD34+ cord blood cells, treatment with SDF-1 dose-dependently suppressed cytokine-induced adhesion. Pretreatment with pertussis toxin reversed adhesion-inhibition, suggesting that activation of G-coupled proteins are involved in the intracellular signalling of this process. These data suggest that SDF-1 not only acts as a chemoattractant but also participates in modulating adhesiveness of haemopoietic progenitors to extracellular matrix components.

Cell Adhesion↗
PubMed1999

Multiple sites of proteolytic cleavage to release soluble forms of hepatocyte growth factor activator inhibitor type 1 from a transmembrane form.

Hepatocyte growth factor activator inhibitor type 1 (HAI-1) is a Kunitz-type serine protease inhibitor, which was identified as a potent inhibitor of hepatocyte growth factor (HGF) activator from the conditioned medium of a human carcinoma cell line. HGF activator is a blood coagulation factor XII-like serine protease that is responsible for proteolytic activation of the inactive single chain precursor of HGF in injured tissues. The predicted sequence of the primary translation product of HAI-1, which has a hydrophobic sequence in its COOH-terminal region, suggested that HAI-1 is first produced in a membrane-associated form. In this study, we identified a transmembrane form of HAI-1 integrated in the plasma membrane of cultured cells using a monoclonal antibody against HAI-1. We also identified several soluble forms of HAI-1 in the conditioned medium of the cells, indicating that multiple sites are present in the transmembrane form of HAI-1 at which proteolytic cleavage releases the extracellular domain. At least two proteases, one of which is a metalloprotease, appear to be responsible for the release. Further, the soluble forms of HAI-1 have different inhibitory activity against HGF activator. These findings suggest that proteolytic processing plays important roles in regulation of the inhibitory activity of HAI-1.

Base Sequence↗
PubMed1999

Therapeutic efficacy of transcranial magnetic stimulation for hereditary spinocerebellar degeneration.

We applied transcranial magnetic stimulation (TMS) as a therapeutic approach for patients with spinocerebellar degeneration (SCD). The subjects were four familial SCD patients (three men and one woman) aged from 27 to 76 years old. They were genetically analysed as two spinocerebellar ataxia type 6 (SCA 6), one SCA 1, and one SCA 7. The durations of their illness ranged from 1 to 7 years. Ten consecutive magnetic pulses were delivered over the scalp corresponding to the right cerebellar hemisphere, the middle of the cerebellum and the left cerebellar hemisphere, respectively, every day for 21 days. In all patients, the time and the number of steps required for a 10 m walk examination were significantly decreased after TMS trial compared with those before TMS. The number of feasible steps in tandem gait test increased. The total length of tracing body balance for 30 seconds measured by gravinometer was significantly decreased. However, nystagmus, dysarthria or incoordination of the upper limbs did not change after TMS trial. It is of interest that the blood flow of the cerebellar hemisphere, putamen and pons were significantly increased during the TMS trial. Although we do not know the exact mechanism by which TMS improved the ataxic gait, we speculate the increase of blood flow in the cerebellum, putamen and pons takes part in the improvement. These findings suggest that TMS over the cerebellum may be an effective therapy for patients with SCD.

Adult↗
PubMed1999

[A trial for peripheral blood stem cell harvest by combination of G-CSF with ABVD regimen in the management of Hodgkin's disease].

We studied the possibility of performing peripheral blood stem cell (PBSC) harvests during the course of ABVD therapy by adding G-CSF to the treatment regimen. Six patients with high-risk Hodgkin's disease (HD) (5 untreated cases with bulky mass and 1 relapsed case) received G-CSF (5 micrograms/kg) subcutaneously from day 8 to day 13 of their first course of ABVD treatment; the numbers of CD34+ cells and CFU-GM were monitored. PBSC harvests were performed on day 12 and day 13 of subsequent ABVD plus G-CSF treatment courses. For all patients tested, we were able to harvest CFU-GM (3.78 +/- 1.19 x 10(5) colonies/kg) for peripheral blood stem cell transplants (PBSCT) by performing 2 to 4 cycles. of apheresis, without any modification to the original ABVD protocol. These findings suggest that ABVD plus G-CSF therapy is a strong candidate for the treatment of patients with high-risk HD who may undergo autologous PBSCT.

Adult↗
PubMed1999

[Prophylaxis of recurrence in superficial bladder carcinoma by intravesical chemotherapy--comparative study between instillation of combined double anticancer agents and single anticancer agent].

We performed a study to compare the usefulness of double or single anticancer agents in the prophylactic treatment after the transurethral resection (TUR) of superficial bladder cancer. We experienced 127 superficial bladder cancer cases. Of these cases, 42 were treated with intravesical adriamycin (ADR) and peplomycin (PEP), 56 with ADR, PEP, epirubicin (epi-ADR) or pirarubicin (THP) only, and the remaining 29 with TUR only. Nonrecurrence rates were significantly higher in the intravesical treated cases than in the cases with TUR only, and also significantly higher in the cases treated with ADR and PEP than the other treated cases. We concluded that intravesical chemotherapy with combined agents was more effective than with a single agent.

Administration, Intravesical↗
PubMed1999

Gene expression of prothrombin in human and rat kidneys: basic and clinical approach.

Prothrombin has remarkable affinity for calcium oxalate crystals. It is produced in renal tubular cells and is detected as a urinary form of prothrombin F1. The aim of this basic study was (1) to isolate prothrombin mRNA from normal human and rat kidneys; (2) to confirm expression level changes in stone-forming rat kidneys; and (3) to analyze the DNA sequence of renal prothrombin. The aim of the clinical investigation was to measure the serum levels of renal prothrombin in clinical cases of various urologic diseases. The expression of prothrombin mRNA in human kidneys and male Wistar rat kidneys was investigated using reverse transcription-PCR, with prothrombin (F1, F2, and thrombin) primers. Renal prothrombin levels were measured in the sera of patients with renal cell carcinoma, renal transplant donors, patients with chronic renal failure, and renal transplant recipients, using an enzyme-linked immunosorbent assay. Expression of cyclophilin as well as prothrombin mRNA could be detected. Prothrombin mRNA expression levels seemed to be increased in stone-forming rats. The DNA sequence of renal prothrombin differed from that of liver prothrombin at three points. Repeated measurements of renal prothrombin showed that values were high during the acute tubular necrosis period and tended to decrease with the recovery of renal function. Prothrombin mRNA expression could be confirmed in human and rat kidneys, as well as in stone-forming rat kidneys. Serum concentration measurements can be considered useful for assessment of recovery from acute tubular necrosis after renal transplantation and for diagnosis of acute rejection.

Adult↗
PubMed1999

[Treatment of stress incontinence by percutaneous bladder neck stabilization (Vesica)].

We experienced 9 cases of percutaneous bladder neck stabilization (Vesica) for patients with urinary incontinence who were diagnosed with stress incontinence from December 1995 to June 1998. None of the patients were able to control continence with any drugs. Chain cystography was performed on all of the patients before and after surgery. The posterior urethro-vesical angle before surgery was over 130 degrees in all of the patients, and it improved after the operation. Moreover, the mean volume of the pad test greatly decreased from 47 g to 1 g. All of the patients were treated with epidural anesthesia. The operation time was less than 60 minutes. The subjective and objective findings were satisfactory. We conclude that percutaneous bladder neck stabilization is a very useful surgical treatment for stress incontinence.

Aged↗
PubMed1998

Molecular cloning and characterization of a novel protein serine/threonine kinase highly expressed in mouse embryo.

By a PCR-based screen for cDNA clones of protein kinases, we have isolated a cDNA clone encoding a novel protein kinase (referred to as EDPK) of 305 amino acids. EDPK has a catalytic domain of 271 amino acids that contains all conserved subdomains characteristic of the protein kinase family. Only short sequences are present at the N- and C-terminal ends outside the catalytic domain. EDPK expressed in Escherichia coli and in mammalian cells phosphorylated serine and threonine, but not tyrosine, residues in an exogenous substrate. The amino acid sequence similarity between EDPK and known serine/threonine kinases was less than 35%. Thus, the newly isolated protein kinase EDPK is a novel member of the serine/threonine kinase family. Northern blot analysis showed that the EDPK mRNA was highly expressed in various stages of mouse embryo development. The expression of the mRNA was also found in a variety of mouse adult tissues. These results suggest that EDPK plays a crucial role in intracellular signaling not only during mouse development but also in adult tissues.

Amino Acid Sequence↗
PubMed1998

Structural organization and chromosomal localization of the human hepatocyte growth factor activator gene--phylogenetic and functional relationship with blood coagulation factor XII, urokinase, and tissue-type plasminogen activator.

The organization and structure of the gene coding for hepatocyte growth factor activator (HGFA) have been determined by isolation of unique clones from a human genomic library. These clones were characterized by restriction mapping, Southern blotting and DNA sequencing. The complete sequence of the gene was determined and found to span about 7.5 kilobases of DNA and consist of 14 exons separated by 13 introns. The coding region of HGFA consists of multiple putative domains that are homologous to those observed in blood coagulation factor XII (FXII). These regions were found as separate exons in the gene, and the exon/intron arrangement was similar to that of FXII, suggesting that the genes for HGFA and FXII have arisen through gene duplication events from a common ancestral gene. The major transcription initiation site is located 75 bp upstream of the translational start codon. The gene was mapped to chromosome 4p16, using spot-blot hybridization on sorted chromosomes and fluorescence in situ hybridization on metaphase chromosome spreads. The phylogenetic and functional relationships between HGFA and FXII as well as urokinase and tissue-type plasminogen activator are discussed.

Base Sequence↗