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S Sekine

Publications and source records attributed to S Sekine.

At least 37 records · Page 2Linked to original sources
PubMed1999

Inhibitory effect of methylene blue-induced photooxidation on intimal thickening of vein graft.

BACKGROUND: We have previously speculated that methylene blue-induced photooxidation of adventitial surface for 5 minutes can completely inhibit the intimal and medial growth of surgically prepared saphenous vein in vitro. In this study, inhibitory effect of methylene blue-induced photooxidation on intimal thickening of vein graft in vivo was investigated. METHODS: Jugular vein grafts were photooxidized in 0.01% methylene blue solution for 5 minutes, and interposed into arterial circulation for 4 weeks in rabbits. Vein grafts were studied by morphometry and immunohistochemistry. RESULTS: The intimal thickening of photooxidized vein grafts were suppressed significantly compared with those in the nonphotooxidized group. Proliferated cell nuclear antigen (PCNA) index (total PCNA-positive cells/total cell count x 100%) of vein graft was significantly higher in the nonphotooxidized group than those in the photooxidized group. CONCLUSIONS: Methylene blue-induced photooxidation is effective in the inhibition of intimal thickening of vein graft interposed in the arterial circulation for 4 weeks in vivo.

Animals↗
PubMed1999

The identity determinants required for the discrimination between tRNAGlu and tRNAAsp by glutamyl-tRNA synthetase from Escherichia coli.

We previously elucidated the major determinant set for Escherichia coli tRNAGlu identity (U34, U35, C36, A37, G1*C72, U2*A71, U11*A24, U13*G22**Alpha46, and Delta47) and showed that the set is sufficient to switch the identity of tRNAGln to Glu [Sekine, S., Nureki, O., Sakamoto, K., Niimi, T., Tateno, M., Go, M., Kohno, T., Brisson, A., Lapointe, J. & Yokoyama, S. (1996) J. Mol. Biol. 256, 685-700]. In the present study, we attempted to switch the identity of tRNAAsp, which has a sequence similar to that of tRNAGlu, and consequently possesses many nucleotide residues corresponding to the Glu identity determinants (U35, C36, A37, G1*C72, and U11*A24). A simple transplantation of the rest of the major determinants (U34, U2*A71, U13*G22**Alpha46, and Delta47) to the framework of tRNAAsp did not result in a sufficient switch of the tRNAAsp identity to Glu. To confer an optimal glutamate accepting activity to tRNAAsp, two other elements, C4*G69 in the middle of the acceptor stem and C12*G23**C9 in the augmented D helix, were required. Consistently, the two base pairs, C4*G69 and C12*G23, in tRNAGlu had been shown to exist in the interface with glutamyl-tRNA synthetase (GluRS) by phosphate-group footprinting. We also found the two elements in the framework of tRNAGln, and determined that their contributions successfully changed the identity of tRNAGln to Glu in the previous study. By the identity-determinant set (C4*G69 and C12*G23**C9 in addition to U34, U35, C36, A37, G1*C72, U2*A71, U11*A24, U13*G22**Alpha46, and Delta47) the activity of GluRS was optimized and efficient discrimination from the noncognate tRNAs was achieved.

Acylation↗
PubMed1999

Effect of modified nucleotides on Escherichia coli tRNAGlu structure and on its aminoacylation by glutamyl-tRNA synthetase. Predominant and distinct roles of the mnm5 and s2 modifications of U34.

Overproducing Escherichia coli tRNAGlu in its homologous host results in the presence of several distinctly modified forms of this molecule that we name modivariants. The predominant tRNAGlu modivariant in wild-type E. coli contains five modified nucleosides: Psi13, mnm5s2U34, m2A37, T54 and Psi55. Four other overproduced modivariants differ from it by, respectively, either the presence of an additional Psi, or the presence of s2U34, or the lack of A37 methylation combined with either s2U34 or U34. Chemical probing reveals that the anticodon loop of the predominant modivariant is less reactive to the probes than that of the four others. Furthermore, the modivariant with neither mnm5s2U34 nor m2A37 has additional perturbations in the D- and T-arms and in the variable region. The lack of a 2-thio group in nucleoside 34, which is mnm5s2U in the predominant tRNAGlu modivariant, decreases by 520-fold the specificity of E. coli glutamyl-tRNA synthetase for tRNAGlu in the aminoacylation reaction, showing that this thio group is the identity element in the modified wobble nucleotide of E. coli tRNAGlu. The modified nucleosides content also influences the recognition of ATP and glutamate by this enzyme, and in this case also, the predominant modivariant is the one that allows the best specificity for these two substrates. These structural and kinetic properties of tRNAGlu modivariants indicate that the modification system of tRNAGlu optimizes the stability of tRNAGlu and its action as cofactor of the glutamyl-tRNA synthetase for the recognition of glutamate and ATP.

Adenosine Triphosphate↗
PubMed1999

Chronic sclerosing sialadenitis of the submandibular gland associated with idiopathic retroperitoneal fibrosis.

We report a case of a 57-year-old man who developed a fibrosclerosing lesion in the submandibular gland and idiopathic retroperitoneal fibrosis (IRF) involving the unilateral periureteral region within a year. Both lesions were resected surgically because of the suspicion of neoplasm. Pathologic examination revealed similar histologic and immunohistochemical features for both lesions, namely, fibrosclerosis with prominent hyalinizing collagen bundles and proliferation of myofibroblastic cells, and a non-neoplastic reactive nature. There was infiltration by lymphocytes with prominent lymph follicles, plasma cells and macrophages. The histologic and immunohistochemical findings suggest that the two lesions were of a similar pathogenesis, which was possibly mediated by macrophages. We think that the present case may be an unusual form of multifocal fibrosclerosis. Although sialolithiasis is thought to be a major pathogenic factor for chronic sclerosing sialadenitis of the submandibular gland, the present case suggests that certain cases might have an etiology similar to IRF.

Biomarkers↗
PubMed1998

Isolation and characterization of a cDNA for human mouse, and rat full-length stem cell growth factor, a new member of C-type lectin superfamily.

cDNA encoding stem cell growth factor (SCGF; 245 aa), a novel human growth factor for primitive hematopoietic progenitor cells, has been previously reported (Hiraoka, A., Sugimura, A., Seki, T., Nagasawa, T., Ohta, N., Shimonishi, M., Hagiya, M. and Shimizu, S. Proc. Natl. Acad. Sci. USA 94, 7577-7582, 1997). Here we report the cloning and characterization of a full-length SCGF cDNA. This protein consists of 323, 328 and 328 aa in the human, murine and rat forms, the latter two of which share 85.1% and 83.3% aa identity, and 90.4% and 90.4% aa similarity to the human protein, respectively. Because the newly identified human clone encodes the protein longer by 78 aa than that previously identified, we term the longer clone as hSCGF-alpha and the shorter one as hSCGF-beta. The computer-assisted homology search reveals that SCGF is a new member of the C-type lectin superfamily, and that SCGF shows the greatest homology to tetranectin among the members of the family (27.2-33.7% aa identity and 46.0-53.6% aa similarity). SCGF transcripts are detected in spleen, thymus, appendix, bone marrow and fetal liver. Fluorescent in situ hybridization mapping indicates that the SCGF gene is located on chromosome 19 at position q13.3 for human form and on chromosome 7 at position B3-B5 for murine form, which are close to flk-2/flt3 ligand and interleukin-11 genes of both human and murine species.

Amino Acid Sequence↗
PubMed1998

Identification and characterization of a novel SH3-domain binding protein, Sab, which preferentially associates with Bruton's tyrosine kinase (BtK).

Protein interaction cloning method was used to identify a novel molecule, Sab, which binds to the SH3 domain of Bruton's tyrosine kinase (Btk), the deficient cytoplasmic tyrosine kinase in human X-linked agammaglobulinemia and murine X-linked immunodeficiency. Immunoprecipitation using the anti-Sab antibody identified the protein product of the gene as a 70 kDa molecule. While Sab does not have a proline-rich sequence, it was shown to bind to Btk through the commonly conserved structure among SH3 domains. Remarkably, Sab exhibited a high preference for binding to Btk rather than to other cytoplasmic tyrosine kinases, which suggests a unique role of Sab in the Btk signal transduction pathway.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Structure of the mouse klotho gene and its two transcripts encoding membrane and secreted protein.

We previously established a novel mouse model for human aging and identified the genetic foundation responsible for it. A defect in expression of a novel gene, termed klotho (kl), leads to a syndrome resembling human aging in mice. The kl gene encodes a single-pass membrane protein whose extracellular domain carries homology to beta-glucosidases. In this report, we present the entire mouse kl gene organization. The mouse kl gene spans about 50 kilobases and consists of five exons. The promoter region lacks a TATA-box and contains four potential binding sites for SP1. We further show that two kl gene transcripts encoding membrane or secreted protein are generated through alternative transcriptional termination. These findings provide fundamental information for further study of the kl gene which may regulate aging in vivo.

Alternative Splicing↗
PubMed1998

Hypoproteinemia caused by tricuspid regurgitation: report of a case.

A case of tricuspid regurgitation (TR) complicated by severe hypoproteinemia is presented herein. A 68-year-old man who had undergone coronary artery bypass grafting (CABG) for postinfarction angina suffered repeated inferior myocardial infarction due to obstruction of the proximal right coronary artery, 3 years after which he developed systemic edema. Investigations revealed TR associated with hypoproteinemia; however, treatment consisting of aggressive diuretic therapy and albumin administration proved ineffective. The hypoproteinemia manifested as protein-losing enteropathy clinically, and the tricuspid valve was replaced to eliminate high venous pressure. The serum protein levels became normalized after the operation. Although TR is generally well tolerated in the absence of pulmonary hypertension, surgical management is recommended for patients with severe protein deficiency resistant to medical treatment.

Aged↗
PubMed1998

Halofuginone inhibits neointimal formation of cultured rat aorta in a concentration-dependent fashion in vitro.

Halofuginone, an anticoccidial quinoazolinone, can specifically inhibit collagen type alpha1 (I) synthesis and gene expression, and also inhibits cultured smooth muscle cell proliferation. The aim of this study was to investigate the effect of halofuginone on neointimal formation of rat aorta after culture in a concentration-dependent manner in vitro. Thoracic aorta of Wistar rats was removed and manipulated to damage the endothelium under sterile conditions, and culture for 15 days in halofuginone-free or halofuginone-added culture medium (n = 20). Segments of cultured aorta were studied by histologic and immunohistochemical methods. Proliferation of neointimal layers consisting of loose multilayer cellular structure was observed in the halofuginone-free control group after 15 days of rat aorta culture, and neointimal formation was significantly decreased as an increasing concentration of halofuginone was added. As with precultured fresh aorta, no intimal proliferation was observed in the cultured segments of aorta with 500 ng/ml halofuginone added to culture medium. The proliferation of cell nuclear antigen index was significantly higher in the halofuginone-free control group than that in the halofuginone-added groups. The present results suggest that halofuginone can inhibit neointimal formation of rat aorta after culture in a concentration-dependent fashion in vitro.

Animals↗
PubMed1998

An effective method for improving hemostasis in aortic root replacement with a composite graft.

Hemostasis during aortic root replacement with a composite graft, consisting of a separate Dacron graft and a valve, was markedly improved by using a supra-annular aortic wall reinforcing suture (SAWR). Between February 1994 and January 1998, 14 consecutive patients (10 men and 4 women) underwent replacement of the aortic valve and ascending aorta with the SAWR technique. No intraoperative bleeding of the aortic proximal suture line or early death occurred in this group. No patient required reoperation for bleeding of anastomoses. Three of 10 patients who underwent elective operations were operated on successfully without blood transfusion. In addition, no clinical complications related to the SAWR technique were observed in the follow-up period. We conclude that the SAWR technique can be performed easily and may be an effective method for improving proximal hemostasis.

Aortic Dissection↗
PubMed1998

Cloning of human polyubiquitin cDNAs and a ubiquitin-binding assay involving its in vitro translation product.

During large-scale in vitro translation analysis of a human full-length cDNA bank, we found a clone producing a remarkably smaller translation product than that expected from the open reading frame. The cDNA encodes a polyubiquitin, UbC, composed of nine tandem repeats of the ubiquitin unit. The bank contained twelve UbC cDNAs including four full-length ones. Sequencing analysis of these clones showed that UbC cDNAs can be classified into two types, UbC1 and UbC2, in each of which there are six polymorphic nucleotide variations. The present UbC cDNA was in vitro translated in a rabbit reticulocyte or wheat germ extract to produce a free ubiquitin labeled with [35S]methionine. The labeled ubiquitin could be used as a substrate for thiol ester formation with ubiquitin-activating enzyme E1 or ubiquitin-conjugating enzyme E2.

Amino Acid Sequence↗
PubMed1998

Microsatellite instability and frameshift mutations in the Bax gene in hereditary nonpolyposis colorectal carcinoma.

We studied microsatellite instability (MI) and bax gene abnormalities in colorectal carcinomas from 36 patients diagnosed as having hereditary nonpolyposis colorectal cancers (HNPCC) according to the clinical criteria (12 with confirmed HNPCC in group A and 24 at high risk of HNPCC in group B) and from 20 randomly selected patients with other colorectal cancers. MI was examined at 4 dinucleotide microsatellite loci and one mononucleotide locus. Frameshift mutations in the bax gene were detected by polymerase chain reaction-single strand conformation polymorphism analysis. MI was detected in 7 of the 12 patients in group A and 12 of the 24 in group B. Three MI patterns were identified: type 1, MI in both mono- and dinucleotide repeats; type 2, MI only in mononucleotide repeats and type 3, MI only in dinucleotide repeats. Most MI-positive patients in group A showed type 1 MI, whereas in group B, 5 showed type 1, 3 showed type 2 and 4 showed type 3. Frameshift mutations in the bax gene correlated strongly with type 1 and type 2 MI. These results indicate that mutations of different DNA mismatch repair genes may cause several types of MI and result in several different clinical phenotypes of HNPCC. The bax gene may be one of the target genes which play a role in the tumorigenesis of HNPCC.

Colorectal Neoplasms↗
PubMed1998

The implication of anthracosis in the development of pulmonary adenocarcinoma.

The relationship between anthracosis, which is the deposition of black dust matter in the lung parenchyma, and the development of pulmonary adenocarcinoma has not been fully characterized. In order to clarify whether background black dust matter deposition could be implicated in the development of pulmonary adenocarcinoma, we measured the level of anthracosis at autopsy in 47 patients who had died of pulmonary adenocarcinoma. Both lungs of all 47 cadavers were examined. Twenty-micrometer sections were cut from formalin-fixed, paraffin-embedded blocks of the largest cut surface of each lung. Black dust matter was extracted from the sections and blotted onto a nitrocellulose membrane. The density of the blotted black dust matter was then analyzed using an imaging densitometer. There were no significant differences in the density of black dust matter deposition between lungs affected by pulmonary adenocarcinoma and control lungs. However, well differentiated adenocarcinomas tended to develop more frequently than poorly differentiated ones in lungs showing less deposition. We found a very strong correlation between the degree of black dust matter deposition and smoking history. Patients with severe anthracosis tended to have a poorer prognosis than those with mild anthracosis.

Adenocarcinoma↗
PubMed1998

Long-term thrombosis after transvenous permanent pacemaker implantation.

To assess the efficacy of prophylactic administration of anticoagulant and antiaggregant drugs to prevent venous thrombosis after long-term transvenous permanent pacemaker implantation, venograms were performed in 100 consecutive patients at the elective replacement of the pacemaker. Mean follow-up period after initial transvenous permanent pacemaker implantation was 6.0 years. The venograms demonstrated normal in 77 patients. The remaining 23 venograms showed venous stenosis in 11 patients and total obstruction in 12 patients. Twenty-one of these 23 patients had venous collateral circulation. No difference was found in the incidence of venous abnormalities according to the route of entry, the lead insulation, the total number of the implanted leads, and anticoagulant and antiaggregant drugs. All these patients have remained asymptomatic. In conclusion, the incidence of venous thrombosis after long-term transvenous pacing is 23% and the causes of venous thrombosis may be endothelial trauma and underlying venous stenosis. As this article describes a retrospective limited study, we cannot find the efficacy of prophylactic administration of anticoagulant and antiaggregant drugs to prevent venous thrombosis formation after transvenous permanent pacemaker implantation. Further prospective study will be needed to assess the efficacy of prophylactic administration of anticoagulant and antiaggregant drugs.

Aged↗
PubMed1998

Surgical treatment of the coronary artery to pulmonary artery fistulas in adults.

Coronary artery to pulmonary artery fistula (CA-PAF) is a rare congenital anomaly. The purpose of this retrospective study was to analyze 11 adult patients with CA-PAFs treated surgically, and to evaluate the surgical management and long-term results. There were no surgical deaths and all patients survived the follow-up periods (mean 7.2 years). All symptomatic patients improved their New York Heart Association functional class. As surgical correction is safe and effective, with good long-term results, all the patients with CA-PAF in adults can be candidates for surgery to prevent life-threatening complications.

Adult↗
PubMed1998

Experimental study on the scavenging effects of ginsenosides on oxygen free radicals using model of heterotopic heart transplantation in rats.

Oxygen-derived free radicals play an important role in myocardial injury associated ischemia and reperfusion. To investigate whether ginsenosides, as an additive agent of cardioplegic solution, can decrease toxicity of oxygen free radicals in myocardial injury, a heterotopic heart transplantation model in Wistar rats was employed. St. Thomas II cold cardioplegia containing ginsenosides 80 mg/l was used in the experimental group. St. Thomas II cold cardioplegia alone was used in the control group. After global ischemia for 60 minutes and reperfusion for 30 minutes of a transplanted heart, SOD activity in the myocardium treated with ginsenosides was significantly higher than that in the control group (N=10, p< 0.01), whereas the MDA in the myocardium treated with ginsenosides were markedly lower than that of the control group (p< 0.01). The amounts of oxygen free radicals in the myocardium treated with ginsenosides were significantly lower than that of the control group (p <0.001). This study demonstrates that ginsenosides, as a proper additive agent of cardioplegic solution, can decrease toxicity of oxygen free radicals, suggesting one of the mechanisms for its protective effects against myocardial ischemia and reperfusion injury.

Animals↗