Biomedical subjects

T Matsuda

Publications and source records attributed to T Matsuda.

At least 145 records · Page 8Linked to original sources

PubMed2001

[Lymph node excision with laparotomy and chemo-radiation therapy for a hepatocellular carcinoma patient with multiple lymph node metastases].

We reported a case of hepatocellular carcinoma (HCC) with multiple lymph node metastases. The patient was a 67-year-old male with C type liver cirrhosis. He underwent microwave coagulation therapy (MCT) for HCC (5 cm and 1.5 cm) 1.5 years before admission. Abdominal CT scan revealed a well-enhanced tumor (2 cm) in caudate lobe of the liver and excessive lymph node metastases, locating in the inferior phrenic, periportal and para-aortic area. The preoperative serum AFP and AFP-L3 levels were 41.9 ng/ml and 93.1%, respectively. At laparotomy, systematic dissection of the enlarged lymph nodes and MCT of the hepatic tumor was performed. After operation, residual inferior phrenic lymph node was treated with irradiation therapy (total 50.4 Gy). The lymph node showed complete response (CR) for about a year and the AFP-L3 level returned to the normal range. After 9 months, a supra-clavicular lymph node was detected on abdominal CT scan. Irradiation therapy (total 45 Gy) in combination with CDDP (100 mg) and 5-FU (4,000 mg) was applied. The lymph node had been assessed as partial response for 6 months. The patient lived quite well after these therapies, but died of hepatic failure 32 months after the initial operation. In conclusion, we recommend this therapeutic strategy using operative excision and chemo-radiation therapy for HCC with multiple lymph node metastases.

Aged↗

PubMed2001

[Early phase II clinical trial of amrubicin hydrochloride in patients with malignant lymphoma].

An early phase II multi-center collaborative study of amrubicin hydrochloride, a novel synthetic anthracycline derivative anticancer agent, was conducted for malignant lymphoma at 12 institutions nationwide. A total of 41 patients were enrolled in this study between January 1988 and October 1990. Of these, 36 patients, six patients with Hodgkin's disease (HD) and 30 patients with non-Hodgkin's lymphoma (NHL), were eligible for the study. The starting dose of amrubicin hydrochloride was 100 mg/m2 (body surface area) and it was administered once every three weeks, in principle. The efficacy was assessed for 34 patients, excluding two patients: one who has not been followed up adequately and the other violated the dosing schedule (once per week). The overall response rates (CR + PR) were 50.0% (3/6) for HD and 42.9% (12/28) for NHL. Furthermore, a relatively high response rate was noted in 8 (36.4%) of 22 NHL patients who had been treated with other anthracycline derivatives prior to the trial. The safety of amrubicin hydrochloride was assessed for 36 eligible patients. Leukopenia (grade 3 or higher) and thrombocytopenia were noted in 21 patients (58.3%) and 10 patients (27.8%), respectively. Anorexia, nausea/vomiting, fever, alopecia, decrease in hemoglobin and elevations of GOT and GPT levels were observed with a relatively high frequency. Other than myelosuppression, the following adverse reactions (grade 3 or higher) occurred during the course of the trial: diarrhea (two patients), alopecia (two patients), stomatitis (one patient), anorexia (one patient), nausea/vomiting (one patient) and fever (one patient). In conclusion, these results indicate that amrubicin hydrochloride is effective in the treatment of patients with malignant lymphoma.

Aged↗

PubMed2001

Functional alteration of brain dopaminergic system in isolated aggressive mice.

The present study examined the effects of social isolation on cortical dopamine (DA) release in vivo and on brain DA receptor functions to study the possible involvement of cortical DA neurons in an antiaggressive effect of the serotonin (5-HT)1A receptor agonist (S)-5-[3-[(1,4-benzodioxan-2-ylmethyl)amino] propoxy]-1,3-benzodioxole HCl (MKC-242). MKC-242 and the DA receptor agonist apomorphine reduced aggressive behavior in isolated mice. MKC-242 increased cortical DA release in vivo in mice, and the effect was antagonized by the 5-HT1A receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)cyclohexanecarboxamide. The basal level of extracellular DA in the frontal cortex was higher in isolated mice than in grouped mice. MKC-242-induced and high K(+)-induced increases in the cortical DA release were less pronounced in isolated mice than in grouped mice. The effect of apomorphine on locomotor activity was more pronounced in isolated mice than in grouped mice. These findings suggest that the isolation stress enhances cortical DA release and the brain DA receptor function and reduces the responses of the dopaminergic terminals to 5-HT1A receptor stimulation and high K(+)-induced depolarization.

Aggression↗

PubMed2000

KB-R7943 inhibits store-operated Ca(2+) entry in cultured neurons and astrocytes.

We have studied cyclopiazonic acid (CPA)-sensitive store-operated Ca(2+) entry (SOCE) in cultured neurons and astrocytes and examined the effect of 2-[2-[4-(4-nitrobenzyloxy)phenyl]]isothiourea (KB-R7943), which is often used as a selective inhibitor of the Na(+)-Ca(2+) exchanger (NCX), on the SOCE. CPA increased transiently intracellular Ca(2+) concentration ([Ca(2+)](i)) followed by a sustained increase in [Ca(2+)](i) in neurons and astrocytes. The sustained increase in [Ca(2+)](i) depended on the presence of extracellular Ca(2+) and inhibited by SOCE inhibitors, but not by a Ca(2+) channel inhibitor. CPA also caused quenching of fura-2 fluorescence when the cells were incubated in Mn(2+)-containing medium. KB-R7943 at 10 microM inhibited significantly CPA-induced sustained increase in [Ca(2+)](i) in neurons and astrocytes. KB-R7943 also inhibited CPA-induced quenching of fura-2 fluorescence in the presence of extracellular Mn(2+). These results indicate that cultured neurons and astrocytes possess SOCE and that KB-R7943 inhibits not only NCX but also SOCE.

Animals↗

PubMed2000

Desensitization, surface expression, and glycosylation of a functional, epitope-tagged type I PACAP (PAC(1)) receptor.

To study desensitization and glycosylation of the type I pituitary adenylate cyclase-activating polypeptide (PACAP) receptor (PAC(1)R), a hemagglutinin (HA) epitope was inserted within the N-terminal extracellular domain, allowing immunological detection of PAC(1)R both in intact and permeabilized cells. PAC(1)R was tagged without loss of functions in ligand binding and ligand-stimulated cAMP production. In transiently transfected COS-7 cells, PAC(1)R was localized both in the plasma membrane and the cytoplasm around the nucleus. By immunoblot analysis, the immunoreactive bands with relative molecular masses ranging from 45 to 70 kDa were detected in the membrane fractions of PAC(1)R-expressing COS-7 cells. Digestion of the membranes with endoglycosidase F or treatment of the cells with tunicamycin decreased the size of the receptor to major bands of smaller size (approximately 45 and 48 kDa), suggesting that these two forms of PAC(1)R represent core proteins. Flow cytometric analysis indicated that the agonist promoted a disappearance of cell surface receptor. In accordance with this observation, preexposure of cells to PACAP38 induced a desensitization of PAC(1)R to the agonist response, although it did not cause a reduction in PAC(1)R mRNA or protein level and even slightly elevated them. These results suggest that agonist-induced desensitization of PAC(1)R involves the receptor sequestration.

Amino Acid Sequence↗

PubMed2000

Fidelity and processivity of DNA synthesis by DNA polymerase kappa, the product of the human DINB1 gene.

Mammalian DNA polymerase kappa (pol kappa), a member of the UmuC/DinB nucleotidyl transferase superfamily, has been implicated in spontaneous mutagenesis. Here we show that human pol kappa copies undamaged DNA with average single-base substitution and deletion error rates of 7 x 10(-3) and 2 x 10(-3), respectively. These error rates are high when compared to those of most other DNA polymerases. pol kappa also has unusual error specificity, producing a high proportion of T.CMP mispairs and deleting and adding non-reiterated nucleotides at extraordinary rates. Unlike other members of the UmuC/DinB family, pol kappa can processively synthesize chains of 25 or more nucleotides. This moderate processivity may reflect a contribution of C-terminal residues, which include two zinc clusters. The very low fidelity and moderate processivity of pol kappa is novel in comparison to any previously studied DNA polymerase, and is consistent with a role in spontaneous mutagenesis.

Base Pair Mismatch↗

PubMed2000

A cytosolic protein-tyrosine phosphatase PTP1B specifically dephosphorylates and deactivates prolactin-activated STAT5a and STAT5b.

Prolactin (PRL) plays a central and crucial role in the regulation of milk protein gene expression in mammary epithelial cells. PRL binding to its cognate receptor leads to receptor dimerization and activation of the tyrosine kinase Janus kinase 2 (JAK2), associated with the membrane-proximal, intracellular domain of the receptor. In turn, JAK2 phosphorylates and activates STAT5, a member of the signal transducers and activators of transcription (STAT) family. We have recently reported that 16 different protein-tyrosine phosphatases (PTP) were expressed in lactating mouse mammary gland and mammary epithelial cells (Aoki, N., Kawamura, M., Yamaguchi-Aoki, Y., Ohira, S., and Matsuda, T. (1999) J. Biochem. (Tokyo) 125, 669-675). We investigated the involvement of each PTP in PRL signaling. Among the 12 phosphatases including SHP-2 examined, a cytosolic phosphatase PTP1B was found to specifically dephosphorylate STAT5a and STAT5b in transfected COS7 and in vitro. Nuclear translocation of STAT5a and STAT5b was largely inhibited upon overexpression of PTP1B. The PRL-dependent transcriptional activation of the beta-casein gene promoter was also inhibited by PTP1B. Furthermore, retrovirus-mediated overexpression of PTP1B resulted in dephosphorylation of endogenous STAT5 and down-regulation of beta-casein gene expression in mammary epithelial COMMA-1D cells when the cells were treated with lactogenic hormones. Endogenous tyrosine-phosphorylated STAT5 proteins in mammary epithelial COMMA-1D cells as well as tyrosine-phosphorylated STAT5a and STAT5b expressed in COS7 cells were co-precipitated by substrate-trapping mutants of recombinant PTP1B. These results strongly suggest that PTP1B dephosphorylates PRL-activated STAT5a and STAT5b, thereby negatively regulating PRL-mediated signaling pathway.

Animals↗

PubMed2000

Proofreading of DNA polymerase eta-dependent replication errors.

Human DNA polymerase eta, the product of the skin cancer susceptibility gene XPV, bypasses UV photoproducts in template DNA that block synthesis by other DNA polymerases. Pol eta lacks an intrinsic proofreading exonuclease and copies DNA with low fidelity, such that pol eta errors could contribute to mutagenesis unless they are corrected. Here we provide evidence that pol eta can compete with other human polymerases during replication of duplex DNA, and in so doing it lowers replication fidelity. However, we show that pol eta has low processivity and extends mismatched primer termini less efficiently than matched termini. These properties could provide an opportunity for extrinsic exonuclease(s) to proofread pol eta-induced replication errors. When we tested this hypothesis during replication in human cell extracts, pol eta-induced replication infidelity was found to be modulated by changing the dNTP concentration and to be enhanced by adding dGMP to a replication reaction. Both effects are classical hallmarks of exonucleolytic proofreading. Thus, pol eta is ideally suited for its role in reducing UV-induced mutagenesis and skin cancer risk, in that its relaxed base selectivity may facilitate efficient bypass of UV photoproducts, while subsequent proofreading by extrinsic exonuclease(s) may reduce its mutagenic potential.

Base Pair Mismatch↗

PubMed2000

Cross-talk between signal transducer and activator of transcription 3 and estrogen receptor signaling.

Interleukin-6 (IL-6) is a multifunctional cytokine that plays important roles in the immune system, hematopoiesis, and acute phase reactions. Estrogens have significant roles in a variety of biological events, such as the development and maintenance of female reproductive organs, and bone and lipid metabolism. Previous studies demonstrated that estrogens suppress IL-6-induced osteoporosis and the growth of multiple myeloma cells by repressing IL-6 and IL-6 receptor gene expression. Here we present a novel mechanism for the inhibitory effect of estrogens on IL-6 function. IL-6-induced activation of signal transducer and activator of transcription 3 (STAT3) activity and STAT3-mediated gene expression were suppressed by 17beta-estradiol (E2) in breast cancer cells. E2-mediated inhibition of STAT3 activation was reversed by tamoxifen, an estrogen receptor (ER) antagonist. We provide evidence that the inhibitory action of ER on STAT3 activity was due to direct physical interactions between STAT3 and ER which represents a novel form of cross-talk between STAT3 and ER signaling pathways.

Cell Line, Transformed↗

PubMed2000

Posttransplant infusion of donor-specific blood induces immunological unresponsiveness in rat hepatic allografts.

BACKGROUND: We previously reported that pretransplant donor-specific blood transfusion (DST) induces CD45RC-CD4+ T cells, Th2-like effector cells, and prolongs rat hepatic allograft survival. Our study investigated the effects of posttransplant DST on rat hepatic allograft survival. METHODS: Three days after transplantation, LEW (RT1(1)) recipient rats with ACI (RT1a) livers were injected i.v. with freshly heparinized donor-specific blood. The time kinetics of CD45RC-CD4+ and CD45RC+CD4+ T cell subsets in hepatic infiltrates were examined. RESULTS: Posttransplant DST significantly prolonged rat hepatic allograft survival. Interferon (IFN)-gamma, interleukin (IL)-12, and IL-18 mRNA levels in hepatic allografts of untreated recipients were significantly greater than in recipients treated with posttransplant DST. However, hepatic allografts of recipients treated with posttransplant DST showed significantly higher IL-4, IL-10, and transforming growth factor (TGF)-beta mRNA levels than untreated recipients. The ratio of CD45RC-CD4+ T cells to CD45RC+CD4+ T cells was significantly higher in hepatic allografts treated with posttransplant DST than in untreated animals. Immunostaining with anti-rat dendritic cell (OX-62) monoclonal antibody revealed that OX-62+ cells were distributed to the splenic red pulp of animals treated with posttransplant DST and to the splenic white pulp in untreated animals. Most OX62+ cells isolated from the spleen of recipients treated with posttransplant DST expressed donor RT1Ba class II major histocompatibility complex antigens, suggesting that OX-62+ cells were of donor origin. CONCLUSION: Posttransplant DST was associated with persistent infiltration of CD45RC-CD4+ T cells, Th2-like effector cells, in rat hepatic allografts, causing immunologic unresponsiveness and establishment of microchimerism in the spleen.

Animals↗

PubMed2000

Protein inhibitor of activated STAT3 regulates androgen receptor signaling in prostate carcinoma cells.

Protein inhibitor of activated STAT3 (PIAS3) is a specific inhibitor of signal transducer and activator of transcription 3 (STAT3). PIAS3 binds to STAT3 and inhibits its DNA-binding activity, and thereby STAT3-mediated gene activation. PIAS1, another member of the PIAS family, was recently shown to interact with the androgen receptor (AR), a nuclear hormone receptor that has an important role in both physiological and pathological processes, and acts as a cofactor for AR. Here we demonstrate that PIAS3 is expressed in prostate cancer cells and its expression is induced in response to dihydrotestosterone (DHT) treatment. Ectopic overexpression of PIAS3 suppressed AR-mediated gene activation induced by DHT-stimulation in LNCaP cells. We provide evidence that these activities were due to direct physical interactions between PIAS3 and AR. These results indicate that PIAS3 acts as a coregulator of AR signaling pathway in prostate cancer cells.

Blotting, Northern↗

PubMed2000

XAB2, a novel tetratricopeptide repeat protein involved in transcription-coupled DNA repair and transcription.

Nucleotide excision repair is a highly versatile DNA repair system responsible for elimination of a wide variety of lesions from the genome. It is comprised of two subpathways: transcription-coupled repair that accomplishes efficient removal of damage blocking transcription and global genome repair. Recently, the basic mechanism of global genome repair has emerged from biochemical studies. However, little is known about transcription-coupled repair in eukaryotes. Here we report the identification of a novel protein designated XAB2 (XPA-binding protein 2) that was identified by virtue of its ability to interact with XPA, a factor central to both nucleotide excision repair subpathways. The XAB2 protein of 855 amino acids consists mainly of 15 tetratricopeptide repeats. In addition to interacting with XPA, immunoprecipitation experiments demonstrated that a fraction of XAB2 is able to interact with the transcription-coupled repair-specific proteins CSA and CSB as well as RNA polymerase II. Furthermore, antibodies against XAB2 inhibited both transcription-coupled repair and transcription in vivo but not global genome repair when microinjected into living fibroblasts. These results indicate that XAB2 is a novel component involved in transcription-coupled repair and transcription.

Amino Acid Motifs↗

PubMed2000

A novel cytoplasmic GTPase XAB1 interacts with DNA repair protein XPA.

The xeroderma pigmentosum group A protein (XPA) plays a central role in nucleotide excision repair (NER). To identify proteins that bind to XPA, we screened a HeLa cDNA library using the yeast two-hybrid system. Here we report a novel cytoplasmic GTP-binding protein, designated XPA binding protein 1 (XAB1). The deduced amino acid sequence of XAB1 consisted of 374 residues with a molecular weight of 41 kDa and an isoelectric point of 4.65. Sequence analysis revealed that XAB1 has four sequence motifs G1-G4 of the GTP-binding protein family in the N-terminal half. XAB1 also contains an acidic region in the C-terminal portion. Northern blot analysis showed that XAB1 mRNA is expressed ubiquitously, and immunofluorescence analysis revealed that XAB1 is localized mainly in the cytoplasm. Consistent with the GTP-binding motif, purified recombinant XAB1 protein has intrinsic GTPase activity. Using the yeast two-hybrid system, we elucidated that XAB1 binds to the N-terminal region of XPA. The deletion of five amino acids, residues 30-34 of XPA, required for nuclear localization of XPA abolished the interaction with XAB1. These results suggest that XAB1 is a novel cytoplasmic GTPase involved in nuclear localization of XPA.

Adenosine Triphosphatases↗

PubMed2000

Na(+)-Ca(2+) exchanger isoforms in rat neuronal preparations: different changes in their expression during postnatal development.

We examined the relative amounts of Na(+)-Ca(2+) exchanger (NCX) isoform mRNAs in cultured neurons, astrocytes and developmental rat brain. NCX1 transcript was predominant in neurons and astrocytes, but NCX2 transcript was about four-fold higher than NCX1 or NCX3 transcript in adult rat cortex. NCX2 transcript in the cortex increased markedly during postnatal development, whereas NCX1 and NCX3 transcripts decreased. Na(+)-dependent 45Ca(2+) uptake in the cortical homogenate increased significantly during postnatal development.

Animals↗

PubMed2000

CV-2619 protects cultured astrocytes against reperfusion injury via nerve growth factor production.

In this study, we examined the effect of the neuroprotective agent 2, 3-dimethoxy-5-methyl-6-(10-hydroxydecyl)-1,4-benzoquinone (CV-2619) on reperfusion injury in cultured rat astrocytes after exposure to hydrogen peroxide (H(2)O(2))-containing medium. CV-2619 (10 nM to 10 microM) significantly attenuated the reperfusion-induced decrease in cell viability. The compound showed an anti-apoptotic effect in this astrocyte injury model. Antioxidants such as ascorbic acid, alpha-tocopherol and reduced glutathione also inhibited H(2)O(2) exposure-induced cytotoxicity. CV-2619 did not affect the levels of reactive oxygen species, but it increased nerve growth factor (NGF) production. The effect of CV-2619 on H(2)O(2) exposure-induced cytotoxicity was blocked by cycloheximide and anti-NGF antibody. The protective effect of CV-2619 was antagonized by the mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase inhibitor 2'-amino-3'-methoxyflavone and the phosphatidylinositol-3 kinase inhibitor wortmannin. These findings suggest that the effect of CV-2619 is mediated at least partly by NGF production in astrocytes and that ERK and phosphatidylinositol-3 kinases play a role in the downstream mechanism.

Animals↗

PubMed2000

Possible involvement of cyclophilin B and caspase-activated deoxyribonuclease in the induction of chromosomal DNA degradation in TCR-stimulated thymocytes.

TCR engagement of immature CD4(+)CD8(+) thymocytes induces clonal maturation (positive selection) as well as clonal deletion (negative selection) in the thymus. However, the cell death execution events of thymocytes during the negative selection process remain obscure. Using a cell-free system, we identified two different DNase activities in the cytosol of in vivo anti-TCR-stimulated murine thymocytes: one that induced chromosomal DNA fragmentation, which was inhibited by an inhibitor of caspase-activated DNase, and another that induced plasmid DNA degradation, which was not inhibited by an inhibitor of caspase-activated DNase. We purified the protein to homogeneity that induced plasmid DNA degradation from the cytosol of anti-CD3-stimulated thymocytes and found that it is identical with cyclophilin B (Cyp B), which was reported to locate in endoplasmic reticulum. Ab against Cyp B specifically inhibited the DNA degradation activity in the cytosol of anti-CD3-stimulated thymocytes. Furthermore, recombinant Cyp B induced DNA degradation of naked nuclei, but did not induce internucleosomal DNA fragmentation. Finally, we demonstrated that TCR engagement of a murine T cell line (EL4) with anti-CD3/CD28 resulted in the release of Cyp B from the microsome fraction to the cytosol/nuclear fraction. Our data strongly suggest that both active caspase-activated DNase and Cyp B may participate in the induction of chromosomal DNA degradation during cell death execution of TCR-stimulated thymocytes.

Animals↗

PubMed2000

Tantalum dust deflagration in a bag filter dust-collecting device.

An accidental tantalum powder deflagration with casualties occurred during the operation of a bag filter dust-collecting device. To understand the mechanism of the incident and its material hazards, experiments for determining the combustibility and ignition characteristics of the tantalum powder were performed. The magnitude of the tantalum dust explosion is classified as severe (K(st)=273), contrary to the classification found in the preceding literature. The minimum ignition energies for both a dust cloud and a dust layer of the tantalum powder were also found to be far lower than previous values. Judging from the observation of the surface with an SEM, the coral-like structure of each particle of the tantalum powder can enhance its fire and explosion hazards and affect its sensitivity to electrostatic sparks by increasing in particle surface area. A thin, non-conductive oxide layer of the tantalum powder surface has a high resistivity and generates electrostatic charge when rubbed with conductive materials like the wall of the collecting device. The authors conclude that the possible cause of the ignition was electrostatic discharge resulting from charging electrostatically.

Accidents, Occupational↗

PubMed2000

Surface microarchitectural design in biomedical applications: in vivo analysis of tissue ingrowth in excimer laser-directed micropored scaffold for cardiovascular tissue engineering.

A micropatterned microporous segmented polyurethane film (20 x 12 mm in size, 30 micrometer thick) with four regions was prepared by excimer laser microprocessing to provide an in vivo model of transmural tissue ingrowth in an open cell-structured scaffold specially designed for cardiovascular tissue engineering. Three microporous regions had the same circular micropores (30 micrometer diameter) but different pore density arrangements (percentage of total pore area against unit area was 0.3%, 1.1%, and 4.5%), and the other region remained nonporous. The covered stent, prepared by wrapping the regionally different density-microporous film on an expandable metallic stent (approximately 3.1 mm in diameter), was delivered to the luminal surface of canine common carotid arteries and placed after expansion of the stent to a diameter of approximately 8 mm using a balloon catheter. At 4 weeks of implantation, all the covered stents (n = 10) were patent. The luminal surfaces of the covered stents were almost confluently endothelialized both in nonporous and microporous regions. Histological examination showed that the neointimal wall was formed by tissue ingrowth from host through micropores (transmural) and anastomotic sites. Thrombus formation occurred frequently in the lowest density porous region and nonporous region. With an increase in pore density, the thickness of the neointimal wall decreased. This study demonstrated how the micropore density of implanted devices influences tissue ingrowth in arterial implantation.

Angioplasty, Balloon↗