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K Suyama

Publications and source records attributed to K Suyama.

At least 37 records · Page 2Linked to original sources
PubMed2001

Coagulation process proceeds on cultured human mesangial cells via expression of factor V.

BACKGROUND: In a previous clinicopathological study, we observed mesangial factor V expression accompanied by the intact form of cross-linked fibrin deposition in the active type of IgA nephropathy. The conversion of prothrombin to thrombin by factor Xa is potently accelerated more than 104-fold by the presence of factor V, which is a membrane-bound cofactor. Another membrane-bound cofactor, tissue factor, is known to play an initiating role in the coagulation cascade and to be synthesized in mesangial cells (MCs) by the stimulation of tumor necrosis factor-alpha (TNF-alpha). However, the synthesis of factor V, which plays on the terminating stage of prothrombin activation, has not been reported previously in MCs by in vitro study. Our current study tested the coagulation process via expression of factor V by the stimulation of proinflammatory cytokine, TNF-alpha, in cultured human MCs. METHODS: To evaluate factor V protein expression, immunoperoxidase staining with densitometric evaluation and Western blot analysis were conducted after stimulation of TNF-alpha. To test factor V activity, stimulated MCs were incubated in combination with factor Xa, prothrombin, fibrinogen and factor XIII, and fibrin production on MCs was assessed after immunoperoxidase staining on the cell surface. In a blocking test using an antibody against factor V, suppression of fibrin production was evaluated to clarify the role of factor V activity. For the evaluation of factor V mRNA expression in cultured human MCs, in situ hybridization and Northern blot analysis were performed. RESULTS: Factor V protein expression in MCs after TNF-alpha stimulation increased both time- and dose-dependently. As a marker of factor V activity with exogenous factor Xa, fibrin production on TNF-alpha-stimulated MCs was increased in a time-dependent manner and was inhibited by the addition of anti-factor V antibody. Factor V mRNA was identified in MCs by in situ hybridization and showed an increase after stimulation with TNF-alpha on Northern blot analysis. CONCLUSIONS: Our data suggest that the coagulation process proceeds on MCs as the result of increased expression of endogenous factor V activity on its cell surface in cooperation with exogenous factor Xa.

Antibodies↗
PubMed2001

Clinical usefulness of a multielectrode basket catheter for idiopathic ventricular tachycardia originating from right ventricular outflow tract.

INTRODUCTION: It often is difficult to determine the optimal ablation site for idiopathic ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT) when the VT or premature ventricular complex (PVC) does not occur frequently. The aim of our study was to evaluate the usefulness of a multielectrode basket catheter for ablation of idiopathic VT originating from the RVOT. METHODS AND RESULTS: Radiofrequency (RF) catheter ablation was performed using a 4-mm tip, quadripolar catheter in 50 consecutive patients with 81 VTs originating from the RVOT with (basket group = 25 patients with 45 VTs) or without (control group = 25 patients with 36 VTs) predeployment of a multielectrode basket catheter composed of 64 electrodes. Deployment of the multielectrode basket catheter was possible and safe in all 25 patients in the basket group. Ablation was successful in 25 (100%) of 25 patients in the basket group and in 22 (88%) of 25 patients in the control group. The total number of RF applications and the number of RF applications per PVC morphology did not differ between the two groups. However, both the fluoroscopic and ablation procedure times per PVC morphology were shorter in the basket group than in the control group (36.8+/-14.1 min vs 52.0+/-32.5 min, P = 0.04; 60.0+/-14.6 vs 81.5+/-51.2 min, P = 0.05). This difference was more pronounced in the 29 patients in whom VT or PVC was not frequently observed. CONCLUSION: The multielectrode basket catheter is safe and useful for determining the optimal ablation site in patients with idiopathic VT originating from the RVOT, especially in those without frequent VT or PVC.

Activation Analysis↗
PubMed2001

Localized right ventricular morphological abnormalities detected by electron-beam computed tomography represent arrhythmogenic substrates in patients with the Brugada syndrome.

AIMS: This study was designed to determine, using electron-beam CT, whether there are morphological abnormalities in patients with the Brugada syndrome and to elucidate the relationship between those abnormalities and arrhythmogenesis. METHODS AND RESULTS: Twenty-six consecutive patients with the Brugada syndrome and 23 age- and gender-matched control subjects (controls) were evaluated for morphological abnormalities using electron beam CT. Electron beam CT demonstrated morphological abnormalities of the right ventricle in 21 (81%) of 26 patients, but in only two (9%) of 23 controls. The sites of morphological abnormalities were the right ventricular outflow tract area in 17 patients and the inferior wall of the right ventricle in four patients. Of the seven patients with monoform premature ventricular contractions recorded only in the acute phase, four of the five patients with premature ventricular contractions from the right ventricular outflow tract area had morphological abnormalities in the right ventricular outflow tract area, and the other two patients with premature ventricular contractions from the inferior wall of the right ventricle had morphological abnormalities in the inferior wall of the right ventricle. CONCLUSION: The sites of morphological abnormalities detected by electron beam CT in patients with the Brugada syndrome were related to the origins of premature ventricular contractions recorded only in the acute phase, which may trigger ventricular fibrillation. These morphological abnormalities may be related to arrhythmogenic substrates in patients with the Brugada syndrome.

Adult↗
PubMed2001

A study of pretreatment nomograms to predict pathological stage and biochemical recurrence after radical prostatectomy for clinically resectable prostate cancer in Japanese men.

BACKGROUND: Accurate pretreatment identification of the risks that prostate cancer has extended beyond the gland and that it will recur would significantly influence practice patterns. Preoperative nomograms to predict such risks have not been developed for the oriental male population. METHODS: Construction of nomograms to predict preoperatively pathological outcome and early biochemical failure following radical prostatectomy in Japanese males was based on logistic regression analysis, with predicted probabilities and 95% confidence intervals for the final model being obtained by repeating the analysis on 1000 bootstrap samples from the original cohort. RESULTS: Prostate-specific antigen level, clinical stage and biopsy Gleason score contributed significantly to the prediction of pathological stage and of biochemical failure in the univariate analysis (p < 0.001). Combined use of these three variables predicted these treatment outcomes better than any single variable (p < 0.001). Nomograms combining these three variables to predict final pathological findings and early biochemical failure were then developed. The medians and 95% confidence intervals of the predicted probabilities are presented in the nomograms. CONCLUSIONS: This information enables clinicians to use their nomograms when counseling Japanese patients, leading to more informed treatment decisions and helping to identify those with a high risk of early biochemical failure. The nomograms may also be used to assure comparability of different treatment modalities in investigational trials.

Aged↗
PubMed2001

Up-regulated TGF-beta mRNA expression in splenic T cells of high IgA-prone mice: a murine model of IgA nephropathy with glomerulosclerosis.

BACKGROUND/AIMS: Recently, we established a high serum IgA-prone inbred (HIGA) mouse strain as a murine model of spontaneous IgA nephropathy by selective mating of high serum IgA ddY mice, and found that they showed enhanced production of glomerular extracellular matrix components with increased expression of TGF-beta mRNA and protein in the kidneys. In this study, we examined the roles of lymphocytes in the development of high serum IgA in this strain. METHODS: We performed flow cytometric analyses of T and B cells in splenic mononuclear cells (SMNCs) from these mice using BALB/c mice as normal controls. We also compared serum TGF-beta1 concentrations and TGF-beta mRNA expression levels in the B-cell-depleted (T-cell-rich) fraction of SMNCs in these mice. RESULTS: HIGA mice showed significantly fewer CD3-positive cells compared with BALB/c mice when young, but not when aged. The CD4/CD8 ratio of HIGA mice was lower than that of BALB/c mice, but this difference was not significant. Although the number of B220-positive cells did not vary significantly, the ratio of surface IgA-positive B cells was significantly increased in both young and adult HIGA mice. The B-cell-depleted SMNCs from HIGA mice exhibited higher levels of expression of TGF-beta and TGF-beta1 mRNA than controls from a young age, which were maintained throughout life, but there were no differences in PDGF, MCP-1 or bFGF expression between these two strains. In contrast to local mRNA expression, serum TGF-beta1 concentration was decreased in HIGA mice compared with BALB/c controls. CONCLUSION: These findings suggest that the mating procedure performed to establish HIGA mice selected for a unique phenotype of local up-regulation of TGF-beta production in the kidneys, as well as T cells that may contribute to both the early and consistently high serum IgA expression and enhanced production of renal extracellular matrix components in HIGA mice. Additionally, TGF-beta1 may act locally, not systemically, in a paracrine or autocrine manner.

Animals↗
PubMed2001

Immortalized gonadotropin-releasing hormone neurons (GT1-7 cells) exhibit synchronous bursts of action potentials.

Although it has been assumed that synchronized firing of gonadotropin-releasing hormone (GnRH) neurons is necessary for pulsatile GnRH secretion, there is no clear evidence for this. In the present study we simultaneously recorded spontaneous action potentials from multiple cells. Immortalized GnRH neurons (GT1-7 cells) were cultured on a multi-electrode dish (MED) and action potentials recorded by an extracellular recording method. One to two weeks after the beginning of culture, spontaneous action potentials appeared, exhibiting bursts composed of 5-10 action potentials. Burst activity was intermittent and periodic with mean burst intervals of 13.3 s. Furthermore, burst activity was recorded almost simultaneously from several micro-electrodes, suggesting that electrical activities of GT1-7 cells were synchronized with each other. Periodic bursts were completely and reversibly blocked by 1-5 microM tetrodotoxin, indicating that voltage-dependent Na(+) channels are involved in their generation. gamma-Aminobutyric acid (GABA) given at a 10-microM concentration shortened inter-burst intervals, whereas 10 microM bicuculline lengthened them. Finally, the gap junctional blockers n-octyl alcohol (1 mM) and carbenoxolone (100 microM) reversibly blocked periodic burst activity. The present study provides direct evidence that the electrical activity of GT1-7 cells exhibits synchronous and periodic bursts composed of action potentials. In addition, endogenous GABA is involved in GT1-7 cells in determining burst frequency. Although the precise mechanism of synchronized burst activities needs to be clarified, gap junctional communications among GT1-7 cells are at least partially involved.

1-Octanol↗
PubMed2001

Asymptomatic brain tumor detected at brain check-up.

Brain check-up was performed in 4000 healthy subjects who underwent medical and radiological examinations for possible brain diseases in our hospital from April 1996 to March 2000. Magnetic resonance imaging revealed 11 brain tumors which consisted of six meningiomas, three pituitary adenomas, one astrocytoma, and one epidermoid cyst. The detection rate of incidental brain tumor in our hospital was 0.3%. Nine patients underwent surgery, with one case of morbidity due to postoperative transient oculomotor nerve paresis. The widespread use of brain check-up may increasingly detect asymptomatic brain tumors. Surgical indications for such lesions remain unclear, and the strategy for treatment should be determined with consideration of the patient's wishes.

Adenoma↗
PubMed2001

[A case of gastrointestinal stromal tumor of rectum, difficult to differentiate from leiomyosarcoma of prostate].

A 70 year-old male was seen at the hospital with the chief complaints of frequent miction and incomplete urinary retention. A hen's egg-sized firm mass was palpable in anterior wall of rectum by digital rectal examination. Intravenous urography showed severe bilateral hydronephroureter. Transrectal ultrasound, CT scan and MRI revealed a mass with 5 cm in diameter between prostate and rectum, and the margin of them were unclear. On needle biopsy of the tumor, leiomyosarcoma of the prostate was suspected. We performed radical cytectomy and created continent urinary reserver. Because the tumor and rectum could not be lysed, part of the rectum was resected. Histological examination showed gastrointestinal stromal tumor (GIST) of rectum. GIST of rectum is a rare entity, and in case of contact with the prostate, it is difficult to differentiate from leiomyosarcoma of prostate.

Aged↗
PubMed2000

Mode of onset of ventricular fibrillation in patients with Brugada syndrome detected by implantable cardioverter defibrillator therapy.

OBJECTIVES: We sought to demonstrate the mode of spontaneous onset of ventricular fibrillation (VF) in patients with Brugada syndrome. BACKGROUND: The electrophysiologic mechanisms of VF in Brugada syndrome have not been fully investigated. METHODS: Nineteen patients (all male, mean age 47 +/- 12 years) with Brugada syndrome were treated with an implantable cardioverter defibrillator (ICD). The implanted devices were capable of storing electrograms during an arrhythmic event. We investigated the mode of spontaneous onset of VF according to the electrocardiographic features during the episode of VF, which were obtained from stored electrograms of ICDs and/or electrocardiographic (ECG) monitoring. RESULTS: During a follow-up of 34.7 +/- 19.4 months (range 14 to 81 months), 46 episodes of spontaneous VF attacks were documented in 7/19 (37%) patients. The event-free period between ICD implantation and the first spontaneous occurrence of VF was 14.6 +/- 12.1 months (range 3.7 to 27.4 months). We investigated 33/46 episodes of VF, for which electrocardiographic features (10 to 20 s before and during VF) were obtained from ICDs and/or ECG monitoring in five patients. A total of 22/33 episodes of VF were preceded by premature ventricular contractions (PVCs), which were almost identical to the initiating PVCs of VF. Furthermore, in three patients who had multiple VF episodes, VF attacks were always initiated by the same respective PVC. The coupling interval of the initiating PVCs of VF was 388 +/- 28 ms. CONCLUSIONS: Spontaneous episodes of VF in patients with Brugada syndrome were triggered by specific PVCs. These findings may provide important insights into the pathophysiological mechanisms causing VF in Brugada syndrome.

Bundle-Branch Block↗
PubMed2000

Chlorination of harman and norharman with sodium hypochlorite and co-mutagenicity of the chlorinated products.

Harman and norharman are widely distributed in the environment and consequently contaminate in domestic waste-water. It has been reported that they have co-mutagenic activity in the presence of non- mutagenic aromatic amines such as aniline and o-toluidine with S9 mix. When these beta-carbolines were treated with sodium hypochiorite under mild conditions, chlorinated derivatives were produced. Among them, 6-chloroharman and 6-chloronorharman showed much more potent co-mutagenic activities than harman and norharman in the presence of o-toluidine toward Salmonella typhimurium TA98 with S9 mix. These results suggest that the chlorination of harman and norharman occurs during disinfection at the sewage plant to produce potent co-mutagens that contaminate river water.

Biotransformation↗
PubMed2000

Bisphenol derivative of allysine for high-performance liquid chromatographic analysis of allysine residue of proteins.

Allysine is the most important precursor of physiologically essential cross-links formation in collagen and elastin and is formed by enzymatic oxidative deamination of lysine residues. Because it is a highly reactive aldehyde, many cross-linking amino acid residues may arise from its reaction with other allysine residues or lysine or even histidine residues. We purified and isolated an allysine bisphenol derivative, 1-amino-1-carboxy-5,5-bis-p-hydroxyphenylpentane (ACPP), from the reaction products of phenol and allysine residue of bovine ligamentum nuchae by acid hydrolysis in 6 M HCl. The structure of ACPP was verified by UV, fast atom bombardment-MS, 1H- and 13C-nuclear magnetic resonance spectroscopies. The optimal reaction condition for ACPP synthesis accompanied by hydrolysis of such proteins was investigated and an ion-paired high-performance liquid chromatographic method for determination of allysine as ACPP was also developed.

2-Aminoadipic Acid↗
PubMed2000

Anti-ischemic effect of a novel cardioprotective agent, JTV519, is mediated through specific activation of delta-isoform of protein kinase C in rat ventricular myocardium.

BACKGROUND: A new 1,4-benzothiazepine derivative, JTV519, has a strong protective effect against Ca(2+) overload-induced myocardial injury. We investigated the effect of JTV519 on ischemia/reperfusion injury in isolated rat hearts. METHODS AND RESULTS: At 30 minutes of reperfusion after 30-minute global ischemia, the percent recovery of left ventricular developed pressure was improved, and the creatine phosphokinase and lactate dehydrogenase leakage was reduced in a concentration-dependent manner when JTV519 was administered in the coronary perfusate both at 5 minutes before the induction of ischemia and at the time of reperfusion. The myocardial protective effect of JTV519 was completely blocked by pretreatment of the heart with GF109203X, a specific protein kinase C (PKC) inhibitor. In contrast, the effect of JTV519 was not affected by alpha(1)-, A(1)-, and B(2)-receptor blockers that couple with PKC in the cardiomyocyte. Both immunofluorescence images and immunoblots of JTV519-treated left ventricular myocardium and isolated ventricular myocytes demonstrated that this agent induced concentration-dependent translocation of the delta-isoform but not the other isoforms of PKC to the plasma membrane. CONCLUSIONS: The mechanism of cardioprotection by JTV519 against ischemia/reperfusion injury involves isozyme-specific PKC activation through a receptor-independent mechanism. This agent may provide a novel pharmacological approach for the treatment of patients with acute coronary diseases via a subcellular mechanism mimicking ischemic preconditioning.

Animals↗
PubMed2000

naked cuticle encodes an inducible antagonist of Wnt signalling.

During animal development, cells have to respond appropriately to localized secreted signals. Proper responses to Hedgehog, transforming growth factor-beta, epidermal growth factor and fibroblast growth factor/Ras signals require cognate inducible antagonists such as Patched, Dad, Argos and Sprouty. Wnt signals are crucial in development and neoplasia. Here we show that naked cuticle (nkd), a Drosophila segment-polarity gene, encodes an inducible antagonist for the Wnt signal Wingless (Wg). In fly embryos and imaginal discs nkd transcription is induced by Wg. In embryos, decreased nkd function has an effect similar to excess Wg; at later stages such a decrease appears to have no effect. Conversely, overproduction of Nkd in Drosophila and misexpression of Nkd in the vertebrate Xenopus laevis result in phenotypes resembling those of loss of Wg/Wnt function. nkd encodes a protein with a single EF hand (a calcium-binding motif) that is most similar to the recoverin family of myristoyl switch proteins. Nkd may therefore link ion fluxes to the regulation of the potency, duration or distribution of Wnt signals. Signal-inducible feedback antagonists such as nkd may limit the effects of Wnt proteins in development and disease.

Amino Acid Sequence↗
PubMed2000

Surface expression of Rh-associated glycoprotein (RhAG) in nonerythroid COS-1 cells.

In the Rh blood system, RhAG (Rh-associated glycoprotein, or Rh50) is thought to be involved in Rh30 (D, CE) expression by forming a protein complex on the red cell surface. To obtain further insight into the Rh complex, we chose nonerythroid COS-1 cells instead of proerythroblast-like K562 cells, which produce endogenous Rh proteins as cell host, for the expression of both RhAG and RhD. The RhAG cDNA was subcloned into a retroviral vector, and a stable COS-1 cell line was then established via retroviral transduction. Surface expression of RhAG on the COS-1 cells was monitored by flow cytometry using mouse monoclonal anti-RhAG(2D10). Under these conditions, we detected significant expression of RhAG on the cell surface, compared to stable COS-1 cells transduced with the vector alone. To confirm the results, we isolated RhAG by immunoprecipitation from the lysate of the COS-1 cells, which were metabolically labeled with [(35)S]-methionine. A strong band of the 32 kd on SDS-PAGE was obtained, corresponding to the results obtained from other cultured cells (K562 cell and others), which always produce partially glycosylated RhAG with a molecular weight of 32 kd. Thus, RhAG was expressed without Rh30 and other Rh-related glycoproteins (LW, glycophorin B) in nonerythroid cells. Using the same strategy, however, we could not express RhD epitopes on COS-1 cells even in the presence of RhAG cDNA, suggesting that other factors might be required for the surface expression of RhD antigen. (Blood. 2000;95:336-341)

Animals↗
PubMed2000

Biological action of keratinocyte growth factor in BeWo cells, a human choriocarcinoma cell line.

Previously, we reported that the expression of keratinocyte growth factor (KGF) is enhanced in secretory phase endometrial and decidual cells in early pregnancy as compared with the expression of KGF in proliferative phase endometrial cells, in humans. In order to clarify the role of KGF in embryo-endometrial interaction, we analyzed the in vitro effect of KGF on the human chorionic gonadotropin (hCG) secretion and on DNA synthesis in chorionic villi which are in close contact with the endometrium/decidua in the early stage of pregnancy. In this study, we used the BeWo cell line, a human choriocarcinoma cell line that possesses the biological features of secreting various placental hormones including hCG. Furthermore, we investigated the expression of KGF receptor (KGF-R) in these cells. KGF significantly stimulated hCG secretion in cultured BeWo cells but did not affect [3H]-thymidine incorporation. KGF-R mRNA was detected in BeWo cells by reverse transcriptase-polymerase chain reaction. These results suggest that the expression of KGF, which is induced in endometrial/decidual cells by progesterone, plays an important role in the embryo-endometrial/ decidual interaction by stimulating hCG secretion rather than affecting cell proliferation.

Cell Division↗
PubMed2000

Prevention of death of axotomized hypoglossal neurones and promotion of regeneration by chitin grafting.

1. Chitin is known to promote skin wound healing. In this study, chitin, prepared from Zuwai crab shell, was used as a bridge between the proximal and distal stumps of cut hypoglossal nerves in shrews. We compared the effects of chitin on the regeneration of transected right hypoglossal nerve axons, with those of porcine dermis, bovine dermal aterocollagen, and autologous nerve bundles. 2. To assess the survival of neurones, the size of neuronal cell body, and number of motoneurones were determined in the absence of any bridged material and in the presence of porcine dermis, bovine dermal aterocollagen, chitin, or autologous nerve bundles as a bridge. 3. Our results revealed a significantly better outcome in chitin and autologous nerve bridged groups; the size of neuronal cell body and number of hypoglossal neurones were higher than in the other groups. Chitin also enhanced the regeneration of neurones; the number of horseradish peroxide positive neurones indicative of repaired axonal processes was significantly higher in chitin and autologous nerve-bridged groups than in other groups. 4. Our results demonstrated that the use of chitin sheet or autograft successfully prevented the death of severed neurones and promoted the regeneration of the lesioned nerve. Although the mechanisms underlying the effects of chitin are still unknown, chitin seems to be a potentially useful biocompatible material for nerve repair and regeneration.

Animals↗
PubMed2000

Biosynthesis of beta1,4- and beta1,beta1-galactopyranosyl xylopyranosides in the mammary gland of lactating cow.

Lactose is a principal carbohydrate in nearly all species of mammalian milk. In order to examine the acceptor substrate specificity of lactose synthase in vivo, D-xylose as an acceptor substrate was injected into the jugular vein of a Holstein cow during lactation, then a milk sample obtained by milking. beta1, beta1-galactopyranosyl xylopyranoside, a nonreducing disaccharide, was separated from the bovine milk sample after elimination of reducing sugars, identified by fast-atom bombardment (FAB)-MS and 1H-NMR analysis. A mixture of beta1,beta1- and beta1, 4-galactopyranosyl xylopyranoside fractions was also obtained by thin layer chromatography from the milk sample and elucidated by electrospray ionization (ESI)-MS and 1H NMR analysis. Comparison of the integrated intensity of the products shows that the beta1,beta1 and beta1,4 isomers are present in a ratio of 1.0 : 1.4, suggesting that D-xylose, transported from capillary blood across the plasma membrane of the mammary gland, was recognized by lactose synthase in its normal and reverse orientation owing to high symmetry of its structure. While the beta1,4-isomer is known as a fragment of the linkage region between the protein and the polysaccharide chain of proteoglycans, the beta1,beta1-isomer has not been identified in vivo. Here, we demonstrate that galactosylation of D-xylose transported from the capillary blood can occur by lactose synthase catalysis in the mammary gland while the usual galactosylation of D-glucose proceeds. In addition, these results suggest that the possibility of endogenous occurrence of the beta,beta-trehalose type disaccharide in the mammary gland of lactating mammals may not be ruled out.

Animals↗