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Biomedical subjects

Tooru Shimosegawa

Publications and source records attributed to Tooru Shimosegawa.

At least 55 records · Page 3Linked to original sources
PubMed2005

Endothelin-1 stimulates contraction and migration of rat pancreatic stellate cells.

AIM: Activated pancreatic stellate cells (PSCs) are implicated in the pathogenesis of pancreatic fibrosis and inflammation. Endothelin-1 (ET-1), which acts through G-protein coupled ET(A) and ET(B) receptors, has several biological activities. We here examined the ability of ET-1 to affect the cell functions of PSCs and the underlying molecular mechanisms. METHODS: PSCs were isolated from the pancreas of male Wistar rats after perfusion with collagenase, and cells between passages two and five were used. Expression of ET-1 and ET receptors was assessed by reverse transcription-PCR and immunostaining. Phosphorylation of myosin regulatory light chain (MLC), extracellular-signal regulated kinase (ERK), and Akt was examined by Western blotting. Contraction of PSCs was assessed on hydrated collagen lattices. Cell migration was examined using modified Boyden chambers. Cell proliferation was assessed by measuring the incorporation of 5-bromo-2'-deoxyuridine. RESULTS: Culture-activated PSCs expressed ET(A) and ET(B) receptors, and ET-1. ET-1 induced phosphorylation of MLC and ERK, but not Akt. ET-1 induced contraction and migration, but did not alter proliferation of PSCs. ET-1-induced contraction was inhibited by an ET(A) receptor antagonist BQ-123 and an ET(B) receptor antagonist BQ-788, whereas migration was inhibited by BQ-788 but not by BQ-123. A Rho kinase inhibitor Y-27632 abolished both contraction and migration. CONCLUSION: ET-1 induced contraction and migration of PSCs through ET receptors and activation of Rho-Rho kinase. ET(A) and ET(B) receptors play different roles in the regulation of these cellular functions in response to ET-1.

Animals↗
PubMed2005

Ellagic acid blocks activation of pancreatic stellate cells.

Activated pancreatic stellate cells (PSCs) play a pivotal role in the pathogenesis of pancreatic fibrosis and inflammation. Ellagic acid is a plant-derived polyphenol found in fruits and nuts, and has anti-oxidant and anti-inflammatory properties. But, little is known about the effects of ellagic acid on PSCs as well as on the activation of signal transduction pathways. We here evaluated the effects of ellagic acid on the activation and cell functions of PSCs. PSCs were isolated from rat pancreas tissue and used in their culture-activated, myofibroblast-like phenotype unless otherwise stated. Ellagic acid inhibited platelet-derived growth factor (PDGF)-BB-induced proliferation and migration, interleukin (IL)-1beta- and tumor necrosis factor (TNF)-alpha-induced monocyte chemoattractant protein-1 production, and expression of alpha-smooth muscle actin and collagen genes. Ellagic acid inhibited PDGF-BB-induced tyrosine phosphorylation of PDGF beta-receptor and the downstream activation of extracellular signal-regulated kinase and Akt. Ellagic acid inhibited IL-1beta- and TNF-alpha-induced activation of activator protein-1 and mitogen-activated protein kinases (extracellular signal-regulated kinase, c-Jun N-terminal kinase and p38 mitogen-activated protein kinase), but not of nuclear factor-kappaB. In addition, ellagic acid inhibited transformation of freshly isolated cells to an activated, myofibroblast-like phenotype. In conclusion, ellagic acid inhibited key cell functions and activation of PSCs.

Animals↗
PubMed2005

Mutations in the serine protease inhibitor Kazal Type 1 (SPINK1) gene in Japanese patients with pancreatitis.

BACKGROUND/AIMS: Recent studies have shown an association between the N34S mutation in the serine protease inhibitor Kazal type 1 (SPINK1) gene and chronic pancreatitis (CP). We here examined the prevalence of SPINK1 mutations in Japanese patients with pancreatitis. METHODS: Genomic DNA was prepared from 80 Japanese patients with CP, 36 patients with acute pancreatitis (AP), and 165 healthy controls. All exons and the promotor region of the SPINK1 gene were amplified by the polymerase chain reaction, and directly sequenced. RESULTS: We found four types of mutation (N34S, IVS1-37T>C, -215G>A, and IVS3 + 2T>C) and two types of polymorphism (-253T>C and 272C>T). The N34S mutation cosegregated with IVS1-37T>C, and was present in 8 CP and 1 AP patients. The -215G>A mutation was in a complete linkage with IVS3 + 2T>C, and was present in 8 CP and 1 AP patients. The prevalences of [N34S; IVS1-37T>C] and [-215G>A; IVS3 + 2T>C] were significantly higher in patients with familial pancreatitis (38 and 13%, respectively) and with idiopathic CP (13 and 16%) than normal subjects (0.6 and 0%). In addition, the frequency of [N34S; IVS1-37T>C] mutation was higher in patients with autoimmune CP (33%). CONCLUSION: The SPINK1 gene mutations were associated with pancreatitis also in Japan.

Acute Disease↗
PubMed2005

Green tea polyphenol epigallocatechin-3-gallate blocks PDGF-induced proliferation and migration of rat pancreatic stellate cells.

AIM: To clarify the effects of epigallocatechin-3-gallate (EGCG) on the platelet-derived growth factor (PDGF)-BB-induced proliferation and migration of pancreatic stellate cells (PSCs). METHODS: PSCs were isolated from rat pancreas tissue and used in their culture-activated, myofibroblast-like phenotype. Cell proliferation was assessed by measuring the incorporation of 5-bromo-2'-deoxyuridine. Cell migration was assessed using modified Boyden chambers. Cyclin D1, p21Waf1, and p27Kip1 expression and phosphorylation of PDGF beta-receptor, extracellular signal-regulated kinase, and Akt were examined by Western blotting. Activation of phospha-tidylinositol 3-kinase was examined by kinase assay using phosphatidylinositol as a substrate. Cell cycle was assessed by flow cytometry after staining with propidium iodide. RESULTS: EGCG at non-cytotoxic concentrations inhibited PDGF-induced proliferation and migration. This effect was associated with the inhibition of cell cycle progression beyond the G1 phase, decreased cyclin D1 and increased p27Kip1 expression. EGCG inhibited tyrosine phosphorylation of PDGF beta-receptor and downstream activation of extracellular signal-regulated kinase and phosphatidylinositol 3-kinase/Akt pathways. CONCLUSION: EGCG inhibited PDGF-BB-induced proliferation and migration of PSCs through the inhibition of PDGF-mediated signaling pathways.

Animals↗
PubMed2005

Activation of JAK-STAT pathway is required for platelet-derived growth factor-induced proliferation of pancreatic stellate cells.

AIM: To clarify the role of Janus kinase-signal transducers and activators of transcription (JAK-STAT) pathway in platelet-derived growth factor (PDGF) induced proliferation in activated pancreatic stellate cells (PSCs). METHODS: PSCs were isolated from rat pancreas tissue, and used in their culture-activated, myofibroblast-like phenotype. STAT-specific binding activity was assessed by electrophoretic mobility shift assay. Activation of Src, JAK2, STAT1, STAT3, and ERK was determined by Western blotting using anti-phospho-specific antibodies. Cell proliferation was assessed by measuring the incorporation of 5-bromo-2'-deoxyuridine. RESULTS: PDGF-BB induced STAT-specific binding activity, and activation of Src, JAK2, STAT1, STAT3, and ERK. Ethanol and acetaldehyde at clinically relevant concentrations decreased basal activation of JAK2 and STAT3. PDGF-induced activation of STAT1 and STAT3 was inhibited by a Src inhibitor PP1 and a JAK2 inhibitor AG490, whereas PDGF-induced activation of ERK was inhibited by PP1, and not by AG490. PDGF-induced proliferation was inhibited by PP1 and AG490 as well as by STAT3 antisense oligonucleotide. CONCLUSION: PDGF-BB activated JAK2-STAT pathway via Src-dependent mechanism. Activation of JAK2-STAT3 pathway, in addition to ERK, may play a role in PDGF-induced proliferation of PSCs.

Animals↗
PubMed2005

A case of acute hepatitis with positive autoantibodies who actually had hepatitis E virus infection.

Hepatitis E virus (HEV) is one of the major causative agents of acute hepatitis in many developing countries. On the other hand, recent intensive investigation has revealed the existence of non-imported cases in industrialized countries. We encountered a sporadic patient with hepatitis E in 1999, who had had no recent travel abroad. He was a 67-year-old Japanese, and his laboratory data were negative for serum markers of hepatitis A, B and C virus infection and positive anti-nuclear antibody, anti-smooth muscle antibody and high level of serum immunoglobulin G. He scored as probable autoimmune hepatitis (AIH) with the scoring system by the international AIH group. He was given a diagnosis of acute cryptogenic hepatitis including acute onset AIH in those days, but the recent retrospective examination with frozen stocked serum revealed his exact diagnosis. In conclusion, we must take HEV infection into consideration for the diagnosis of cryptogenic acute hepatitis even in the developed countries, and some patients with hepatitis E could demonstrate positive for autoantibodies similar to clinical features of AIH. This case demonstrated the needs for further studies about clinical feature of acute hepatitis E virus infection.

Journal Article↗
PubMed2005

High prevalence of hepatitis delta virus infection detectable by enzyme immunoassay among apparently healthy individuals in Mongolia.

A previous study revealed a high prevalence of hepatitis B surface antigen (HBsAg) and hepatitis delta virus (HDV) RNA among 249 apparently healthy individuals (mean+/-standard deviation age, 48.4+/-13.9 years; 126 males and 123 females) in Ulaanbaatar, Mongolia. To investigate further the prevalence of HDV infection there, the same serum samples obtained from the cohort were tested for the presence of immunoglobulin G (IgG) class antibody to HDV (anti-HDV) by a newly developed enzyme-linked immunosorbent assay using recombinant hepatitis delta antigen protein expressed in the pupae of silkworm as the antigen probe. Anti-HDV was detected in 42 persons (16.9%), among whom 22 (52.4%) were positive for HBsAg and 20 (47.6%) had detectable HDV RNA. Among 170 persons with anti-HBc in the absence of HBsAg, 20 (11.8%) tested positive for anti-HDV, and 1 of the 20 subjects was positive for HDV RNA. Of note, none of 55 anti-HBc-negative persons had anti-HDV, supporting the specificity of the anti-HDV assay. The optical density (OD) value of anti-HDV was significantly higher among HDV RNA-positive subjects (n=21) than among HDV RNA-negative subjects (n=21) (2.513+/-0.514 vs. 0.836+/-0.550, P<0.0001). The present study confirmed the extremely high prevalence of HDV infection in Mongolia, and identified a person who was positive for both anti-HDV and HDV RNA despite negativity for HBsAg and HBV DNA probably due to viral interference. The anti-HDV assay may be useful for further epidemiological studies on HDV infection in larger cohorts in urban and rural areas of Mongolia, where elucidation of the transmission route of HDV is required urgently.

Adult↗
PubMed2005

Helicobacter heilmannii infection in a child after successful eradication of Helicobacter pylori: case report and review of literature.

An 11-year-old boy with Helicobacter pylori-associated duodenal ulcer was successfully treated with a combination of lansoprazole, amoxicillin, and clarithromycin. Endoscopy and gastric biopsies were repeated 2 and 12 months later, showing ulcer healing and eradication of H. pylori. However, a 3-year follow-up study demonstrated H. heilmannii in the antral mucosa based on its characteristic morphology and positive urease test and negative culture. The patient had no contact with domestic animals such as cats and dogs. A 7-day course with lansoprazole, amoxicillin, and clarithromycin was performed again, resulting in successful eradication of the organism. Pediatric cases with H. heilmannii infection reported are reviewed.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2005

Serum pepsinogen concentrations as a measure of gastric acid secretion in Helicobacter pylori-negative and -positive Japanese subjects.

BACKGROUND: Although previous studies have indicated that serum pepsinogen I levels, as well as the pepsinogen I/II ratio, were positively correlated with maximal gastric output, the relationship may be different between Helicobacter pylori-negative and -positive subjects. The aim of this study was to investigate the relation between serum pepsinogen concentrations and gastric acid secretion in H. pylori-positive and -negative subjects separately. METHODS: The presence of H. pylori infection, the serum pepsinogen concentrations, and gastric acid secretion were investigated in 182 subjects without localized lesions in the upper gastrointestinal tract. Serum pepsinogen concentration was measured by radioimmunoassay, and maximal gastric acid output was estimated by an endoscopic gastrin test, as we have previously shown. RESULTS: In H. pylori-positive subjects, serum pepsinogen I levels and the pepsinogen I/II ratio were significantly correlated with gastric acid secretion, although the latter showed a better correlation (r=0.40 and 0.53, respectively). On the other hand, in H. pylori-negative subjects, serum pepsinogen concentrations were well correlated with acid secretion (r=0.57), but there was no relation between the pepsinogen I/II ratio and acid secretion. CONCLUSIONS: The correlations between serum pepsinogens and gastric acid secretion differ, depending on the presence or absence of H. pylori infection. With the use of serum pepsinogens as a simple measure of gastric acid secretion, therefore, consideration of H. pylori infection status is needed. Because the determination of the acid secretory level has some clinical implications in both H. pylori-positive and -negative subjects, its estimation by serum pepsinogen concentrations can be of practical use.

Adult↗
PubMed2005

Tumor necrosis factor-alpha mediates pancreatitis responses in acinar cells via protein kinase C and proline-rich tyrosine kinase 2.

BACKGROUND & AIMS: Although tumor necrosis factor alpha is implicated as an important mediator of the inflammatory response in acute pancreatitis, its role in other pathologic features of the disease remains unknown. We investigated the role for tumor necrosis factor alpha in cytoskeletal responses and the underlying signaling mechanisms in pancreatic acinar cells. METHODS: In isolated rat pancreatic acini and AR42J cells, we determined the effect of tumor necrosis factor alpha on the actin cytoskeleton by rhodamine-phalloidin. Using pharmacological and molecular approaches, we assessed the involvement of protein kinase C, Src kinases, and proline-rich tyrosine kinase 2 in the process. We also studied the involvement of these signaling pathways in tumor necrosis factor-alpha-induced nuclear factor-kappaB activation and apoptosis. RESULTS: Tumor necrosis factor-alpha increased the tyrosine phosphorylation of proline-rich tyrosine kinase 2 in acinar cells. The broad-spectrum protein kinase C inhibitor and the Src kinase inhibitor both inhibited tumor necrosis factor-alpha-induced proline-rich tyrosine kinase 2 phosphorylation, but at different tyrosine residues. Using protein kinase C isoform-specific inhibitors and the antisense approach, we showed that protein kinase C delta and mediate proline-rich tyrosine kinase 2 tyrosine phosphorylation. Tumor necrosis factor-alpha caused disorganization of the actin cytoskeleton by a mechanism dependent on protein kinase C, Src kinases, and proline-rich tyrosine kinase 2. Inhibition of protein kinase C, but not Src kinases, decreased tumor necrosis factor-alpha-induced apoptosis. Furthermore, with antisense transfections, we showed that protein kinase C delta and , but not proline-rich tyrosine kinase 2, mediate tumor necrosis factor alpha-induced nuclear factor-kappaB activation. CONCLUSIONS: Tumor necrosis factor-alpha activates proline-rich tyrosine kinase 2 to cause cytoskeletal disorganization and nuclear factor-kappaB to cause inflammatory response, and it triggers cell death signaling through divergent mechanisms mediated by protein kinase C. The results provide insights into the mechanisms in pancreatic acinar cells that link tumor necrosis factor alpha to critical processes in acute pancreatitis.

Acute Disease↗
PubMed2005

Accumulation of CCR5+ T cells around RANTES+ granulomas in Crohn's disease: a pivotal site of Th1-shifted immune response?

Immunological abnormalities are implicated in the pathogenesis of inflammatory bowel disease (IBD), that is, Crohn's disease and ulcerative colitis. In particular, Crohn's disease is considered to be a T helper type 1 (Th1)-shifted disease. Chemokines and their receptors are involved in various immune responses including Th1- and Th2 responses. In this study, we analyzed chemokines and their receptors by immunohistochemistry, using frozen sections derived from 33 patients with Crohn's disease and 24 with ulcerative colitis. In inflamed mucosa, small mononuclear cells predominantly expressed CCR5 and CXCR3, the receptors selectively expressed on Th1 cells, without significant differences between Crohn's disease and ulcerative colitis. We then focused on the noncaseating granulomas that are characteristic of Crohn's disease. Granuloma cells, observed in all the layers of intestinal tissues, were positive for RANTES/CCL5 protein along their cell membranes. Lymphocytes surrounding granulomas were mostly CCR5+ and CXCR3+ T cells with CD4+ and CD8+ cells at similar frequencies. Granuloma cells were positive for RANTES mRNA by in situ hybridization. By contrast, lymphoid aggregates in Crohn's disease and lymphoid follicles in the normal intestinal mucosa were characterized by abundant B cells, a predominance of CD4+ T cells over CD8+ T cells, and low frequencies of cells expressing CCR5 or CXCR3. Together with the notion that granuloma cells are possible antigen-presenting cells, our results suggest that the noncaseating granulomas could be one of the crucial sites of Th1-shifted immune responses in Crohn's disease.

Adolescent↗
PubMed2005

Autoimmune pancreatitis with hepatic inflammatory pseudotumor.

We report a case of autoimmune pancreatitis (AIP) with hepatic inflammatory pseudotumor (IP). The patient was clinically diagnosed as having multiple metastatic tumors originated from cholangiocellular carcinoma as well as autoimmune pancreatitis and underwent left lobectomy of the liver. Histological examination showed a diffuse or dense lymphoplasmacytic infiltration with obliterating phlebitis but an absence of neoplastic proliferation both in the liver tumor and in the biopsy specimen of the pancreas. Abundant IgG4-positive plasma cells were seen in the lesions. This is the first case report that shows a simultaneous occurrence of hepatic IP and AIP, suggesting that these lesions appeared on the background of the recently proposed entity of IgG4-related systemic disease.

Autoimmune Diseases↗
PubMed2005

Living related liver transplantation for acute fulminant hepatitis B: experience from two possible hyper-acute cases.

Fulminant hepatic failure, which is represented by fulminant hepatitis, is fatal in most cases unless prompt liver transplantation is performed. Even if liver transplantation is performed, irreversible neurological damage is often complicated. In this case report, we describe two cases of fulminant hepatitis induced by acute hepatitis B virus infection, both of which were successfully rescued by living related liver transplantation without significant complications. The case 1 was a 45-year-old Japanese male. He complained general malaise and anorexia. His local physician diagnosed him as acute hepatitis B, and referred to our hospital. Due to severe coagulopathy, plasma exchange was performed 3 times. However, his hepatic coma progressed rapidly along with rapid decrease of both his direct/indirect bilirubin (D/T) ratio and serum blood urea nitrogen (BUN) levels. Living related liver transplantation was performed under the diagnosis of acute fulminant hepatitis B. The case 2 was a 34-year-old Japanese male. His complaints were fever and skin rush. He was referred to our hospital under the diagnosis of acute hepatitis B. On the second day after admission, he developed grade II hepatic coma, which deteriorated into grade III in spite of intensive therapy including plasma exchange. He also demonstrated rapid decrease of both D/T ratio and serum BUN level. Living related liver transplantation was performed on the next day. Both cases recovered without any evidence of neurological sequelae. In general, it is extremely difficult to rescue fulminant hepatitis by conservative treatments, particularly in cases with rapid progression. Although emergency liver transplantation may be an only option to rescue in such a case, living related liver transplantation has an advantage in view of urgent organ donation over cadeveric transplantation.

Acute Disease↗
PubMed2005

A patient with clinical features of acute hepatitis E viral infection and autoimmune hepatitis.

Hepatitis E virus (HEV) is one of the major causative agents of acute hepatitis in many developing countries. Recent intensive examination has revealed the existence of non-imported cases in industrialized countries. The patient was a 25-year-old Japanese female with acute hepatitis. Laboratory test demonstrated positive anti-nuclear antibody (ANA), anti-smooth muscle antibody (ASMA) and high level of serum immunoglobulin G (IgG). The patient was negative for serum markers of hepatitis A, B or C virus infection. She demonstrated a clinical course similar to severe autoimmune hepatitis, including response to prednisolone therapy. After a few years, with the availability of tests for the serum antibodies to HEV, we examined the frozen stocked sera of the patient and found her exact diagnosis was acute hepatitis E. Although we could not detect HEV-RNA, which is positive only in limited period of acute phase, serum IgA and IgG antibodies to HEV were positive and the titer of IgA and IgG antibodies were declined with the time course. In conclusion, we must take into consideration of HEV infection for the diagnosis of acute cryptogenic hepatitis including autoimmune hepatitis. Further studies are feasible to understand the pathogenesis of liver injuries induced by HEV infections.

Acute Disease↗
PubMed2005

Dissipating excess energy stored in the liver is a potential treatment strategy for diabetes associated with obesity.

For examining whether dissipating excess energy in the liver is a possible therapeutic approach to high-fat diet-induced metabolic disorders, uncoupling protein-1 (UCP1) was expressed in murine liver using adenoviral vectors in mice with high-fat diet-induced diabetes and obesity, and in standard diet-fed lean mice. Once diabetes with obesity developed, hepatic UCP1 expression increased energy expenditure, decreased body weight, and reduced fat in the liver and adipose tissues, resulting in markedly improved insulin resistance and, thus, diabetes and dyslipidemia. Decreased expressions of enzymes for lipid synthesis and glucose production and activation of AMP-activated kinase in the liver seem to contribute to these improvements. Hepatic UCP1 expression also reversed high-fat diet-induced hyperphagia and hypothalamic leptin resistance, as well as insulin resistance in muscle. In contrast, intriguingly, in standard diet-fed lean mice, hepatic UCP1 expression did not significantly affect energy expenditure or hepatic ATP contents. Furthermore, no alterations in blood glucose levels, body weight, or adiposity were observed. These findings suggest that ectopic UCP1 in the liver dissipates surplus energy without affecting required energy and exerts minimal metabolic effects in lean mice. Thus, enhanced UCP expression in the liver is a new potential therapeutic target for the metabolic syndrome.

Adipose Tissue↗
PubMed2005

[Endoscopic therapy for Barrett's esophagus].

There are many foreign reports about the endoscopic ablation therapy for Barrett's esophagus. Endoscopic ablation therapy include thermal therapy (electrocoagulation, laser etc.), photodynamic therapy or endoscopic resection and so on. Ablation of Barrett's esophagus by these therapy in combination with adequate acid suppression lead to mucosal replacement by squamous epithelium. But the true value of these endoscopic therapy has not been fully investigated. Further studies are required.

Barrett Esophagus↗