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Biomedical subjects

Y Matsuura

Publications and source records attributed to Y Matsuura.

At least 19 recordsLinked to original sources
PubMed1995

Telomerase activity in gastric cancer.

Although many genetic alterations have been reported in gastric cancer, it is not known whether all gastric tumors are capable of indefinite proliferative potential, e.g., immortality. The expression of telomerase and stabilization of telomeres are concomitant with the attainment of immortality in tumor cells; thus, the measurement of telomerase activity in clinically obtained tumor samples may provide important information useful both as a diagnostic marker to detect immortal cancer cells in clinical materials and as a prognostic indicator of patient outcome. Telomerase activity was analyzed in 66 primary gastric cancers with the use of a PCR-based assay. The majority of tumors (85%) displayed telomerase activity, but telomerase was undetectable in 10 tumors (15%), 8 of which were early stage tumors. Most of the tumors with telomerase activity were large and of advanced stages, including metastases. Survival rate of patients of tumors with detectable telomerase activity was significantly shorter than that of those without telomerase activity. Alterations of telomere length (reduced/elongated terminal restriction fragments) were detected in 14 of 66 (21%) gastric cancers, and all 14 had telomerase activity. Cellular DNA contents revealed that all 22 aneuploid tumors had detectable telomerase activity. The present results indicate that telomerase activation may be required as a critical step in the multigenetic process of tumorigenesis, and that telomerase is frequently but not always activated as a late event in gastric cancer progression.

Base Sequence↗
PubMed1995

Molecular cloning of a human protein that binds to the retinoblastoma protein and chromosomal mapping.

We have isolated distinct clones for cellular proteins that bind to the retinoblastoma protein by direct screening of cDNA expression libraries using purified pRB as a probe. The total nucleotide sequence of one of these clones, RBQ-3, was determined and found to encode a protein of 66 kDa localized in the nucleus. The RBQ-3 preferentially binds to underphosphorylated pRB. The region used for binding to this protein was mapped to the E1A-binding pocket B of pRB, which has sequence similarity to the general transcription factor TFIIB. We have mapped the gene to 1q32 using polymerase chain reaction analysis on a human-hamster hybrid cell panel and chromosomal fluorescence in situ hybridization.

Amino Acid Sequence↗
PubMed1995

Differential expression of the two types of histone H2A genes in wheat.

Five histone H2A cDNA clones have been isolated from a wheat cDNA library. They were divided into two groups, termed type 1 and type 2, based on their deduced amino acid sequences and their gene expression patterns. Three type 1 clones had ORFs encoding proteins similar to angiosperm histone H2As known so far, whereas two type 2 clones encoded an identical protein, which was more similar to Norway spruce (gymnosperm) H2A than to the angiosperm H2As. The C-terminus of the type 2 H2A was shorter than that of the type 1 H2As and lacked the characteristic SPKK motif that is conserved in angiosperm H2As. Northern analysis revealed that the mRNA levels of the type 1 H2A genes were high in proliferating cells during germination and in various tissues of young seedlings, while the mRNA levels of the type 2 genes were high in non-proliferating cells in which the type 1 gene was poorly expressed. This result suggests that the expression of these two groups of H2A genes is differently regulated during development in wheat.

Amino Acid Sequence↗
PubMed1995

Molecular states of fungal nuclease composed of heterogeneous subunits as estimated from the effects of urea and chelating agents.

Fungal nuclease composed of subunits with molecular weights of 8.0 x 10(4) (80K subunit), 5.0 x 10(4) (50K subunit), and 2.5 x 10(4) (25K subunit) (K. Ito, Y. Matsuura, and N. Minamiura (1994) Arch. Biochem. Biophys. 309, 160-167) was inactivated by urea and dissociated into its subunits. The urea inactivation depended on the concentration of urea, the incubation period and the temperature. The urea-inactivated enzyme had about 25% activity restored by removal of urea, and the native form of the enzyme was also reconstituted. The urea inactivation and the dissociation of subunits were almost completely prevented by Ca2+ but not by glycerol. The enzyme was also inactivated by ethylenediaminetetraacetic acid (EDTA). From this method of inactivation, the 50K and 25K subunits were still associated, but the complex showed no nuclease activity. About 80% of the activity of the EDTA-inactivated enzyme was restored by the addition of Ca2+ or Sr2+ and 20-40% by Mn2+, Ba2+, Mg2+, or Co2+. The reactivation of the enzyme by these metal ions was accompanied by the reconstitution of the native form of the enzyme. The enzyme was inactivated by ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid (EGTA) at much higher concentrations compared with the inactivation by EDTA. On the other hand, dissociation of the subunits by EGTA proceeded in a manner similar to that of the inactivation of the enzyme by EDTA. The 50K and 25K subunits were still associated, and the complex showed nuclease activity. These results indicated that the enzyme contains two kinds of metal ions. One metal ion, represented by Ca2+, is thought to stabilize the quanternary structure of the enzyme, especially to connect the 80K subunit and the complex of the 50K and 25K subunits. Another metal ion, represented by Mg2+, is thought to be bound to the complex of the 50K and 25K subunits and to be required for activity appearance of the complex. Along with these results, possible molecular states of the enzyme under various conditions are proposed.

Aspergillus↗
PubMed1995

Correlating telomerase activity levels with human neuroblastoma outcomes.

Telomerase activity was analysed in 100 neuroblastoma cases. Although telomerase activity was not detected in normal adrenal tissues or benign ganglioneuromas, almost all neuroblastomas (94%) did express it, suggesting an important role for telomerase in neuroblastoma development. Neuroblastomas with high telomerase activity had other genetic changes (for example, N-myc amplification) and an unfavourable prognosis, whereas tumours with low telomerase activity were devoid of such genetic alterations and were associated with a favourable prognosis. Three neuroblastomas lacking telomerase activity regressed (stage IVS). Thus telomerase expression may be required as a critical step in the multigenetic process of tumorigenesis, and two different pathways may exist for the development of neuroblastoma.

Adrenal Gland Neoplasms↗
PubMed1995

Nuclear localization of the truncated hepatitis C virus core protein with its hydrophobic C terminus deleted.

The core protein of hepatitis C virus (HCV) is considered to be cleaved from the N terminus of the large precursor polyprotein by cellular signalase. The HCV cDNA encoding the core protein was expressed (i) in monkey COS cells by a plasmid expression vector driven by the SR alpha promoter, and (ii) in insect cells by a recombinant baculovirus. The expressed product had an M(r) of 22,000 and was located in the cytoplasm. When the C-terminal hydrophobic domains were deleted, however, the truncated core proteins were translocated into the nucleus. The truncated core proteins were located in the nucleus even when they were expressed as a fusion protein with E. coli beta-galactosidase, which is essentially localized in the cytoplasm. Plasmids containing HCV cDNAs with a deletion in one of the regions encoding clusters of basic amino acids were expressed in COS cells and the localization of the core protein was examined. The residues PRRGPR were suggested to play an important role in nuclear localization. HCV is an RNA virus and its life cycle was originally considered to be confined to the cytoplasm; the present study, however, suggests that the HCV core protein can translocate into the nucleus under certain circumstances.

Amino Acid Sequence↗
PubMed1995

Characterization of an established human hepatoma cell line constitutively expressing non-structural proteins of hepatitis C virus by transfection of viral cDNA.

A human hepatoma cell line constitutively expressing proteins of hepatitis C virus (HCV) was established by transfection with cDNA encoding part of the virus nonstructural (NS) genome region. Proteins consistent with authentic processing at NS3/NS4A, NS4A/NS4B and NS4B/NS5A were identified. Pulse-chase experiments indicated that the cleavage between NS3 and NS4A occurred first and cleavage at other sites followed. Expression of specific surface antigens in response to the presence of HCV proteins was analysed by flow cytometry. A significant increase in CD26 expression was observed in cells expressing the HCV proteins. CD26 plays an important role in cellular signal transduction. Its upregulation in response to the presence of HCV proteins may play a role in viral pathology.

Base Sequence↗
PubMed1995

Proteolytic activity of NS3 serine proteinase of hepatitis C virus efficiently expressed in Escherichia coli.

The serine proteinase of hepatitis C virus (HCV) non-structural protein NS3 was efficiently expressed in an active form as a fused protein with oligohistidine in Escherichia coli. The recombinant fusion protein was purified to near homogeneity by affinity chromatography on a metal chelation column. Trans-cleavage activity of this protein was investigated by using the substrate NS5 protein expressed in insect cells. The purified serine proteinase trans-cleaved the partially purified NS5 protein. In contrast, the NS3 proteins with mutations at the proposed catalytic site, Ser1165 or His1083, lost the trans-cleavage activity. Analysis of the authentic enzyme and variants with site-directed mutations provides a useful tool for understanding the structure-function relationship of the NS3 serine proteinase. We then developed an in vivo trans-cleavage assay system by coexpression of the NS3 proteinase and the NS5 substrate in E coli, and examined the effect of known inhibitors of serine proteinase. Inhibition of its proteolytic activity by N-p-tosyl-L-lysine chloromethyl ketone (TLCK) was observed, but only at high concentrations. The in vitro and in vivo trans-cleavage assays for NS3 serine proteinase will facilitate efficient testing for inhibitors of the replication of HCV and specific treatment for hepatitis C.

Baculoviridae↗
PubMed1995

[Evaluation of serum granulocyte colony stimulating factor and granulocyte counts in patients with extracorporeal circulation].

To clarify the physiologic roles of granulocyte colony stimulating factor (G-CSF) in increasing granulocyte after extracorporeal circulation (ECC). The serum levels of G-CSF, C3a, granulocyte elastase and granulocyte count were examined in 26 patients undergone open heart surgery. These patients were divided into two groups, the long perfusion group (11 patients) and the short perfusion group (15 patients). Granulocyte increased immediately after ECC and reached maximum 48 hours after ECC in both groups. C3a showed significant increase at the end of ECC and decreased rapidly after ECC in both group. G-CSF showed high levels 3 and 6 hours after ECC in the short perfusion group and moderate increase prolonged until 48 hours after ECC in the long perfusion group. Granulocyte elastase showed high levels 6 hours after ECC and decreased to the normal value 48 hours after ECC in the short perfusion group, and high levels prolonging until 48 hours after ECC in the long perfusion group. Increase of granulocyte count might be affected with increase of compliment (C3a) and G-CSF at the early and late phase after ECC, respectively. Granulocyte elastase increased differently by the duration of perfusion time.

Adult↗
PubMed1995

Mac-1 expression and superoxide generation of the peripheral polymorphonuclear leukocyte following gastrectomy and esophagectomy.

The aim of this study was to evaluate the characteristics of the polymorphonuclear leukocyte (PMN) function after surgical stress. We investigated Mac-1 expression and superoxide generation by peripheral PMNs and serum granulocyte-colony stimulating factor (G-CSF) concentrations in 15 patients who underwent either gastrectomy (n = 8) or esophagectomy (n = 7). The serum G-CSF rapidly increased within 24 hours after operation. The maximum levels of serum G-CSF in the cases of esophagectomy were about 5-8 fold those of gastrectomy, although the increases in PMN counts within 24 hours of esophagectomy were lower than those after gastrectomy. Mac-1 expression and superoxide generation by PMN counts and serum G-CSF. After esophagectomy, Mac-1 expression on peripheral PMNs remained elevated through the 7th day after operation, while superoxide generation by PMNs in response to PMA declined to below preoperative levels after the 3rd day. These results suggest that, after major surgery such as esophagectomy, there is a discrepancy between Mac-1 expression and superoxide generation by the peripheral PMN despite a high level of serum G-CSF.

Aged↗
PubMed1995

[Complications of endocardial biopsy in heart transplant patients].

Despite the increasing use of alternative techniques, endomyocardial biopsy remains the primary method for diagnosing cardiac allograft rejection. Between March 1986 and May 1994, 2,894 endomyocardial biopsies performed on 183 heart transplant patients were reviewed. A total of 53 (1.8%) complications occurred. 33 (1.1%) complications were associated with the introduction, including carotid puncture (0.9%), neurological reaction (0.1%), and pneumothorax (0.1%). Complications during biopsy included arrhythmias (0.4%) and ventricular perforation (0.2%). In addition, we observed three episodes of allergic reaction to a reusable biotome, three episodes of liver biopsy, and one case of pacemaker dislodgement. All complications were without significant long-term sequelae. In contrast to the cardiomyopathy population, no severe ventricular perforations or deaths occurred. Thus although endomyocardial biopsy has some risk, it continues to be a safe and effective way of monitoring rejection.

Adolescent↗
PubMed1995

[A case report of closing aortic dissection with cardiac tamponade which developed re-dissection three weeks later].

A 57-year-old female with hypotension and consciousness disturbance was referred to our institute. Echocardiography and plain CT revealed cardiac tamponade, but no apparent evidence of aortic dissection was obtained. With sudden onset of hypotension, she was immediately operated without information of aortography, enhanced CT, and MRI. Approximately 200 g of pericardial hemorrhage and slight subadventitial hematoma was grossly found and surface ultrasonography revealed the mild localized intramural hematoma (crescent-shaped translucent layer of at most 5 mm in width) at the proximal ascending aorta. Because neither false lumen with blood flow nor intimal flap was found, pericardial drainage without aortic replacement was performed. However, DeBakey type II of aortic dissection with wide false lumen was found with CT and MRI within three weeks, and re-operation was carried out. The dissection ranged from the ostium of right coronary artery to the beginning of innominate artery, but did not involve the coronary arteries and major branches of aortic arch. The surface ultrasonography and transesophageal echocardiography, as well as preoperative CT and MRI, demonstrated that false lumen was thrombosed except at the anterior aspect of mid-portion of ascending aorta. The ascending aorta was replaced. A careful follow-up is mandatory for even a localized intramural hematoma, which can progress into aortic dissection in a short period.

Aortic Dissection↗