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Y Muto

Publications and source records attributed to Y Muto.

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

Analysis of Fas system in pulmonary injury of graft-versus-host disease after rat intestinal transplantation.

The lung is one of the primary targets of acute graft-versus-host disease (GVHD), which is the principal complication that occurs after allogeneic intestinal transplantation. The purpose of this study is to investigate the involvement of Fas/Fas ligand system in pulmonary injury after rat semi-allogeneic intestinal transplantation. The lungs were serially harvested from LEW x BN F1(LBNF1) recipients of either LEW heterotopic intestinal allografts or LBNF1 isografts, on days 1, 3, 5, 9, and 13 posttransplant. In light microscopy, pulmonary injury became apparent on day 13 in the allogeneic combination, showing a thickening of the alveolar septa. The incidence of apoptosis, examined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) biotin nick end-labeling, was observed to increase steadily in the alveolar cells accompanied by a progression of GVHD. In an immunohistochemical study, Fas was constitutively expressed in the lung, although Fas ligand was expressed most extensively on day 9. The immunoreactivity of both Fas and Fas ligand were observed in alveolar cells, in addition to leukocytes. An analysis by reverse transcription polymerase chain reaction also revealed that the expression of Fas mRNA was constitutive without any significant change, although that of Fas ligand mRNA increased substantially and peaked on day 9, which was significant compared to the isogeneic combination. In conclusion, transcriptionally up-regulated Fas ligand and increased number of apoptosis suggests that the Fas system may play a role in the pathophysiology of GVHD-induced pulmonary injury.

Animals↗
PubMed1999

Age-related decrease in brain-derived neurotrophic factor gene expression in the brain of the zitter rat with genetic spongiform encephalopathy.

The zitter rat exhibits a progressive degradation in neuronal cells and genetic spongiform encephalopathy with age. In order to elucidate the involvement of the expression of the neurotrophic factor in neuropathology of the rat, we quantified mRNA levels of neurotrophic factors (nerve growth factor, brain-derived neurotrophic factor (BDNF), and neurotrophin-3, ciliary neurotrophic factor and glial-cell-line-derived neurotrophic factor) in the zitter rat brain. Expression of the BDNF gene was lower in the zitter rat brain (cerebrum, cerebellum, and brainstem regions). Interestingly, kinase activity of mitogen activated protein kinase (MAPK) Erk2 involved in the expression of BDNF was also down regulated, despite an unchanging expression of MAPK protein. These results show the possible involvement of a MAPK pathway in BDNF mRNA reduction in the zitter rat brain.

Aging↗
PubMed1999

Solution structures of the first and second RNA-binding domains of human U2 small nuclear ribonucleoprotein particle auxiliary factor (U2AF(65)).

The large subunit of the human U2 small nuclear ribonucleoprotein particle auxiliary factor (hU2AF(65)) is an essential RNA-splicing factor required for the recognition of the polypyrimidine tract immediately upstream of the 3' splice site. In the present study, we determined the solution structures of two hU2AF(65) fragments, corresponding to the first and second RNA-binding domains (RBD1 and RBD2, respectively), by nuclear magnetic resonance spectroscopy. The tertiary structure of RBD2 is similar to that of typical RNA-binding domains with the beta1-alpha1-beta2-beta3-alpha2-beta4 topology. In contrast, the hU2AF(65) RBD1 structure has unique features: (i) the alpha1 helix is elongated by one turn toward the C-terminus; (ii) the loop between alpha1 and beta2 (the alpha1/beta2 loop) is much longer and has a defined conformation; (iii) the beta2 strand is (188)AVQIN(192), which was not predicted by sequence alignments; and (iv) the beta2/beta3 loop is much shorter. Chemical shift perturbation experiments showed that the U2AF-binding RNA fragments interact with the four beta-strands of RBD2 whereas, in contrast, they interact with beta1, beta3 and beta4, but not with beta2 or the alpha1/beta2 loop, of RBD1. The characteristic alpha1-beta2 structure of the hU2AF(65) RBD1 may interact with other proteins, such as UAP56.

Amino Acid Sequence↗
PubMed1999

Stable gene expression with VSV-G pseudotyped-retrovirus vector in the rat liver.

BACKGROUND: Pseudotyped-retrovirus-mediated gene transfer to the regenerating rat liver was investigated in vivo and the findings were compared with those for retrovirus-mediated gene transfer. MATERIALS AND METHODS: Four weeks prior to gene transfer, the spleen was transpositioned to the left subcutaneous position to develop a port-splenic shunt. Twenty-four hours after a partial hepatectomy (68%) was performed, the liver was perfused in situ and kept in contact with either a pseudotyped-retrovirus vector encoding LacZ (7 x 10(7) cfu/ml, Group 1) or a retrovirus vector encoding LacZ (1 x 10(4) cfu/ml, Group 2) for 30 min. The animals were sacrificed at various points after gene transfer, and X-gal staining, reversed polymerase chain reaction (RT-PCR), and ONPG assay were performed to detect the transferred LacZ cDNA. RESULTS: In X-gal staining, the transferred LacZ cDNA started to show a strong beta-galactosidase activity in 30 to 50% of the hepatocytes at 3 days after gene transfer. Positive staining continued to be recognized until 28 days with a slight decrease in its intensity thereafter. On the other hand, Group 2 animals showed weak staining, which was observed in about 10 to 15% of the hepatocytes from 3 days after gene transfer and then decreased thereafter. In RT-PCR, positive mRNA of LacZ was detected constitutively until 28 days after gene transfer in Group 1, whereas two-thirds of the samples showed a negative band in Groups 2 at 3 days after gene transfer. CONCLUSION: In conclusion, the pseudotyped-retrovirus vector was useful in establishing a stable and strong expression of the in vivo gene transfer, while targeting the regenerating liver.

Animals↗
PubMed1999

Analysis of the Fas system and Bcl-2 in rat liver allograft rejection.

BACKGROUND: Apoptosis is involved in the mechanism of cell death observed in liver allograft rejection. The liver cells are sensitive to Fas-mediated apoptosis; however, little is known about the involvement of the Fas system in liver allograft rejection. We used rat models to investigate the expression of Fas/Fas ligand and apoptosis-related proteins during liver allograft rejection. MATERIALS AND METHODS: DA rats to Lewis, and Lewis to Lewis orthotopic liver transplantation were performed; liver samples were collected on days 1, 3, 5, 7, and 9 postoperatively (each n = 3). Apoptosis was monitored by TUNEL and electron microscopy. The expression of Fas, FasL, bcl-2, and bax was examined at the mRNA level and by means of immunohistochemistry. RESULTS: The TUNEL index in the allografts and isografts on day 7 was 20.1 +/- 1.5 and 7.7 +/- 2.6/1000 cells, respectively. Fas and bax mRNA were constitutively expressed in both of the groups. The expression of Fas ligand mRNA in the allografts which rose on day 5 was 10 times stronger compared to that in the isografts. On the other hand, bcl-2 mRNA was generally expressed in the isografts while it decreased in the allografts. The immunohistochemical analysis also showed an increased reactivity of Fas ligand on day 5 in the allograft, which was observed both in parenchymal and nonparenchymal cells. CONCLUSIONS: These results strongly suggest that Fas/Fas ligand interaction mediates the liver injury during allograft rejection. In addition, other regulatory factors of apoptosis, such as bcl-2, might also be involved in this pathogenesis.

Animals↗
PubMed1999

Structural basis for recognition of the tra mRNA precursor by the Sex-lethal protein.

The Sex-lethal (Sxl) protein of Drosophila melanogaster regulates alternative splicing of the transformer (tra) messenger RNA precursor by binding to the tra polypyrimidine tract during the sex-determination process. The crystal structure has now been determined at 2.6 A resolution of the complex formed between two tandemly arranged RNA-binding domains of the Sxl protein and a 12-nucleotide, single-stranded RNA derived from the tra polypyrimidine tract. The two RNA-binding domains have their beta-sheet platforms facing each other to form a V-shaped cleft. The RNA is characteristically extended and bound in this cleft, where the UGUUUUUUU sequence is specifically recognized by the protein. This structure offers the first insight, to our knowledge, into how a protein binds specifically to a cognate RNA without any intramolecular base-pairing.

Amino Acid Sequence↗
PubMed1999

Protective effects of ulinastatin against ischemia-reperfusion injury.

We investigated the protective effect of urinary trypsin inhibitor (ulinastatin: UTI) in vitro, in relation to the neutrophil activity in hepatic ischemia/reperfusion (I/R) injury. The rat liver was removed and preserved in cold Ringer's lactate solution for 60 min, followed by 120 min of reperfusion with oxygenated perfusate. The rats were divided into four groups (n = 8 in each group). The livers were perfused with Krebs-Henseleit (K-H) solution containing no additives in group 1, 50,000 U/kg of UTI in group 2, 3.5 x 10(6) of neutrophils in group 3, and both neutrophils and UTI in group 4. In group 3, the AST and ALT levels were always higher than those in other three groups at any point evaluated (P < 0.01) and the LDH levels were observed to be significantly higher than those in other three groups at 0, 5, 10, 60, and 90 min after reperfusion (P < 0. 01). These increase were suppressed by additional pretreatment with UTI in group 4. The bile flow during reperfusion was significantly suppressed in group 3 compared to that of group 4, at both 30 (P < 0. 01) and 60 (P < 0.05) min after reperfusion. The MPO activity after reperfusion in group 3 also significantly increased compared to other three groups (P < 0.01). These data thus suggest that UTI ameliorated the ischemia/reperfusion injury in vitro by inhibiting of neutrophil accumulation in the postischemic liver.

Animals↗
PubMed1999

Early detection of apoptosis and fas ligand expression in hepatic graft-versus-host disease after rat small bowel transplantation.

BACKGROUND: The liver is one of the primary targets of acute graft-versus-host disease (GVHD), which is the principal complication that occurs after allogeneic intestinal transplantation. The purpose of this study is to investigate the involvement of the Fas/Fas ligand system in hepatic GVHD after rat semiallogeneic intestinal transplantation. MATERIALS AND METHODS: Liver samples were serially harvested from LEW x BN F(1) (LBNF(1)) recipients of either LEW heterotopic intestinal allografts (group 1) or LBNF(1) isografts (group 2), on Days 1, 3, 5, 9, and 13 posttransplant. RESULTS: In group 1, hepatic injuries as assessed by either serum aspartate aminotransferase (AST) level, alanine aminotransferase (ALT) level, or cellular infiltration on HE staining became apparent after Day 13. The incidence of apoptosis, examined by terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end-labeling (TUNEL), was observed to steadily increase in the liver from Day 5 accompanied by a progression of GVHD: 17.5 +/- 3.1 and 3.1 +/- 0.4 cells/field (200x) in groups 1 and 2, respectively. In an immunohistochemical study, Fas was constitutively expressed in the liver in both groups, while Fas ligand was expressed most extensively on Day 13 in group 1. Immunoreactivity of both Fas and Fas ligand was observed in hepatocytes, in addition to leukocytes. Analysis by reverse transcription polymerase chain reaction also revealed the expression of Fas mRNA to be constitutive in both groups, while that of Fas ligand mRNA increased significantly from Day 5 and peaked on Day 13 in group 1, and the expression was 10 times stronger than that for isogeneic combination (group 2). CONCLUSION: Early detection of upregulated Fas ligand and increased apoptosis is thus considered to be potentially a useful tool for the diagnosis of hepatic GVHD.

Animals↗
PubMed1999

Characteristics of hepatocellular carcinoma in patients with negative virus markers: clinicopathologic study of resected tumors.

Fifty-one cases of resected hepatocellular carcinoma (HCC) were retrospectively analyzed to evaluate the clinicopathologic features of HCC in patients with negative virus markers. The data were compared between three groups: hepatitis B surface antigen positive (HB, n = 11), hepatitis C virus antibody positive (HC, n = 21), and non-BC (both HbsAg and HCVAb negative, n = 12). Seven patients were excluded from the study because of operative death (n = 3), a history of alcohol abuse (n = 3), or the presence of dual positive HB and HC virus markers (n = 1). The data were analyzed by either an analysis of variance (ANOVA) or a contingency table. The age of the non-BC patients was higher (63.0 +/- 4.1, +/- SE) than that of HB patients (54.0 +/- 3.2, p < 0.05) but was identical to that of the HC group (62.0 +/- 1.8). Among the preoperative laboratory data, the serum glutamic oxaloacetate and glutamate pyruvate transaminoses (GOT, GPT) levels were statistically lower in the non-BC patients (32.8 +/- 4.8 and 28.0 +/- 4.4 IU/L, respectively) than in the HB and HC patients. The pathologic features of the resected specimens in the non-BC patients showed more invasive growth than in specimens from the HB or HC patients. The clinical stages (defined based on the criteria of the Japanese Association of Hepatocellular Carcinoma) were also more advanced in the non-BC patients than in the other groups. Postoperative survival time showed no significant difference among the groups. In conclusion, the non-BC patients had comparatively greater invasive growth and more advanced clinical stages than the HB and HC patients, despite the absence of liver cirrhosis, and so demonstrated the same poor survival data as observed in the HB and HC patients.

Adult↗
PubMed1999

Common bile duct blood clot: an unusual cause of ductal filling defects for calculi.

We report a case of obstructive jaundice caused by a blood clot in the common bile duct in a 75-year-old man with cirrhosis. Five years prior to his admission, he had undergone a left hepatectomy for hepatocellular carcinoma. At the present admission, he appeared icteric, and endoscopic retrograde cholangiography revealed filling defects in the common bile duct. Choledochotomy was therefore performed for possible common duct stones, and exploration of the duct showed blood clot casts filling the duct. The casts were easily removed, and the patient's postoperative course was uneventful. However, he developed ascites and jaundice 1 month later and died of liver failure approximately 3 months after undergoing the choledochotomy. Autopsy revealed hemorrhagic necrosis in the proximal intrahepatic duct of the posterior segment, which was considered to be the cause of the observed hemobilia, as well as the blood clot in the common bile duct at surgery. We report this rare case and discuss the cause of hemobilia.

Aged↗
PubMed1999

Radiation-associated ischemic coloproctitis: report of two cases.

Radiation-associated ischemic coloproctitis is a rare clinical entity caused by vascular insufficiency to the rectosigmoid colon. It most commonly occurs after radiotherapy for gynecological cancer. We present herein the cases of two patients who developed radiation-associated coloproctitis with transmural necrosis and eventual perforation. Perforation of the rectosigmoid colon occurred 3.5 years after radiotherapy in case 1, a 46-year-old woman, and presented as a well-defined small area of transmural necrosis. Conversely, in case 2, a 55-year-old woman, it occurred 1.5 years after radiotherapy, and presented as segmental, diffuse transmural necrosis. The lesion in case 1 had been caused by intramural vascular obliteration due to marked fibrosis of the bowel wall, while that in case 2 had been caused by occlusion of the mesenteric artery with thrombosis. Both patients underwent Hartmann's resection without rectal excision, and survived the perforative event.

Colon, Sigmoid↗
PubMed1999

Analyses of microsatellite instability and the transforming growth factor-beta receptor type II gene mutation in sporadic human gastrointestinal cancer.

Microsatellite instability (MSI) and transforming growth factor-beta receptor type II (RII) gene mutation have been reported in many types of tumors and their instance seem to vary among the tumors investigated. To determine the relation between MSI and RII gene mutation in sporadic gastrointestinal cancer development, 21 esophageal, 19 gastric, and 27 colorectal cancers were investigated. The presence of MSI was screened by single strand conformation polymorphism (SSCP) method using six microsatellite markers. RII gene mutations were detected by SSCP method and direct sequencing. MSI was detected in seven of 21 (33.3%) esophageal cancers, three of 19 (15.8%) gastric cancers and seven of 27 (25.9%) colorectal cancers. However, RII gene mutations were observed in only two of seven (28.6%) MSI-positive colorectal cancers. Our data suggest that among sporadic gastrointestinal cancers, colorectal cancers seem to be the most frequent target organ involved in carcinogenesis through RII gene mutation, which thus appears to be related to organ specificity.

Base Sequence↗
PubMed1999

Increased 9,13-di-cis-retinoic acid in rat hepatic fibrosis: implication for a potential link between retinoid loss and TGF-beta mediated fibrogenesis in vivo.

BACKGROUND/AIMS: During hepatic fibrosis, hepatic stellate cells (HSCs) transform into myofibroblastic cells and lose their intracellular droplets of retinyl esters, the storage form of vitamin A. Recently, we have demonstrated that 9,13-di-cis-retinoic acid (RA), a geometric isomer identified as a stable and major metabolite of vitamin A in circulation, stimulates the synthesis of plasminogen activator (PA) and induces PA/plasmin-dependent latent transforming growth factor (TGF)-beta activation in HSC cultures, probably via induction and activation of RA receptor (RAR) alpha. The aim of the present study was to address a potential link between the loss of retinyl esters to increased formation of RA(s), which might play a role in facilitating TGF-beta-mediated liver fibrogenesis in vivo. METHODS: We examined the effect of 9,13-di-cis-RA on transactivating activity of RARalpha in HeLa cells as well as its effect on PA- and TGF-beta-dependent collagen synthesis in rat and human HSC cultures. We measured the changes in 9,13-di-cis-RA levels both during activation of rat HSCs in vitro and during porcine serum-induced rat hepatic fibrosis in vivo and correlated this with RAR alpha/beta, PA, TGF-beta and type I procollagen mRNA expression in the fibrotic liver. RESULTS: 9,13-di-cis-RA transactivated RARalpha, and provoked PA/plasmin and TGF-beta-dependent procollagen synthesis in HSCs. 9,13-di-cis-RA levels were increased both in activated HSCs in vitro and in fibrotic liver accompanying the enhanced expression of RAR alpha/beta, PA, TGF-beta and procollagen in vivo. CONCLUSIONS: These findings suggest a potential link between 9,13-di-cis RA formation and hepatic fibrosis via formation of TGF-beta in vivo, and thus provide further insight into the biologic role of retinoids during hepatic fibrogenesis.

Animals↗
PubMed1999

Elevated intracellular IFN-gamma levels in circulating CD8+ lymphocytes in patients with fulminant hepatitis.

BACKGROUND/AIMS: Fulminant hepatitis usually takes a rapidly progressive course, terminating in death within a short period. Experimental studies have demonstrated that immunological mechanisms play an important role, especially those involving virus-specific CD8+ cytotoxic T lymphocytes and their production of interferon-gamma (IFN-gamma). However, there are no immunological markers for prediction of the development of fulminant hepatitis in man. METHODS: Peripheral blood lymphocytes from four patients with fulminant hepatitis, six with acute hepatitis and 11 healthy volunteers as normal controls were analyzed. Intracellular IFN-gamma production in both CD8 positive and negative T lymphocytes was assessed by flow cytometry. RESULTS: Populations of CD8+ IFN-gamma+ T lymphocytes were significantly increased in patients with fulminant hepatitis, as compared with those with acute hepatitis and normal controls. Production of IFN-gamma in CD8+ T lymphocytes of patients with fulminant hepatitis was also elevated, furthermore significantly correlating with the prothrombin time (r=-0.64, p<0.01). CONCLUSIONS: The capacity for IFN-gamma production by CD8+ lymphocytes is up-regulated in fulminant hepatitis, and this may be important for the development of fulminant hepatitis.

Adult↗
PubMed1999

Analyses of microsatellite instability and the transforming growth factor-beta receptor type II gene mutation in sporadic breast cancer and their correlation with clinicopathological features.

To determine the incidence of microsatellite instability (MSI) and its relationship with both clinicopathologic parameters and patient survival, 101 cases of breast cancer were investigated. In addition, transforming growth factor-beta (TGF-beta) receptor type II (RII) gene mutation was also examined to clarify the relation to MSI in breast cancer development. MSI and RII gene mutation were screened by single strand conformation polymorphism (SSCP). The mutations of the RII gene were confirmed by a direct sequence. An association between the MSI status and the clinicopathological features was examined to assess the potential of the MSI status as a prognostic indicator in sporadic breast cancer cases. MSI was detected in 12 of 101 (11.9%) breast cancer cases. The positive MSI breast cancer cases showed relatively more advanced disease than negative MSI cases, and also exhibited relatively poorer prognoses. No RII gene mutations were observed in any of the breast cancer cases. Our data suggest that the MSI status may thus be a useful indicator for the prognosis of sporadic breast cancer cases. However, the breast seems to be an infrequent target organ for cancer development through RII gene mutations. As a result, tumor progression through this pathway appears to be related to organ specificity. For positive MSI breast cancers, other target genes therefore still need to be identified.

Breast Neoplasms↗
PubMed1999

Effects of cytokines on the binding of leukocytes to cultured rat hepatocytes and on the expression of ICAM-1 by hepatocytes.

Adhesions of leukocytes to hepatocytes and sinusoidal endothelial cells mediates the induction and progression of hepatic injury. However, in contrast to endothelial cells, information regarding the regulation of interactions between leukocytes and hepatocytes is limited. In the present study, we investigated the effect of inflammatory mediators including lipopolysaccharide (LPS), staphylococcal enterotoxin B (SEB), interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) on the adhesion of polymorphonuclear leukocytes or lymphocytes to primary cultured rat hepatocytes, and on the expression of intercellular adhesion molecule-1 (ICAM-1) gene in hepatocytes. Both polymorphonuclear leukocyte and lymphocyte adhesion to hepatocytes were enhanced after exposure of hepatocytes to IFN-gamma and TNF-alpha, but not after exposure to LPS, SEB or IL-1beta. The adhesion induced by either IFN-gamma or TNF-alpha was inhibited by monoclonal antibodies against ICAM-1 or lymphocyte function-associated antigen-1 (LFA-1). Nonstimulated hepatocytes expressed faintly ICAM-1 mRNA, which increased slightly during the culture period. ICAM-1 mRNA expression was up-regulated to a greater extent by incubating hepatocytes with IFN-gamma or TNF-alpha, and peaked after 12 hr of incubation with TNF-alpha and after 24 hr with IFN-gamma. These results indicate that IFN-gamma and TNF-alpha induce the expression of ICAM-1 on parenchymal hepatocytes and that the LFA-1-ICAM-1 pathway plays an important role in the interaction between hepatocytes and neutrophils or lymphocytes.

Animals↗