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Biomedical subjects

Michio Imawari

Publications and source records attributed to Michio Imawari.

33 records · Page 2Linked to original sources
PubMed2003

A case of primary esophageal tuberculosis diagnosed by identification of Mycobacteria in paraffin-embedded esophageal biopsy specimens by polymerase chain reaction.

We present a case of primary esophageal tuberculosis diagnosed by polymerase chain reaction (PCR) of paraffin-embedded esophageal biopsy specimens. A 42-year-old Japanese woman visited our clinic because of dysphagia. Radiologic and endoscopic examinations revealed a stenotic lesion with reddish mucosa and multiple ulcers in the middle esophagus. There was no associated lesion outside the esophagus. Histological and bacteriological studies of esophageal biopsy specimens and gastric aspirates did not give a definitive diagnosis. However, mycobacterial DNA was detected by PCR of paraffin-embedded esophageal biopsy specimens. She then was diagnosed as having primary esophageal tuberculosis. The esophageal mucosal lesion almost healed after 1 month of antituberculosis medication with residual annular stenosis which was resolved later by endoscopic balloon dilation.

Adult↗
PubMed2003

Proteasome is required for class I-restricted presentation by Fcgamma receptor-mediated endocytosis in primary biliary cirrhosis.

There is a considerable database on the effector mechanisms for CD8 recognition of PDC-E2 in primary biliary cirrhosis (PBC). In particular, the specific roles of MHC class I, the mitochondrial autoepitope, and the liver-specific T cell precursor frequency, are defined for HLA-A2.1 patients. There is evidence for a role of MHC class I-mediated presentation of exogenous antigens, or cross-presentation, in the development of the antimitochondrial response and a contributory role of Fcgamma receptor-mediated uptake of autoantigen-autoantibody complexes for the induction of a PDC-E2 specific autoreactive CTL response. Based on this background, we examined potential intracellular pathways for processing the immunodominant mitochondrial autoantigen, PDC-E2, by dendritic cells (DC). In particular, we studied the effects of the proteasome inhibitor lactacystin and the endosomal acidification inhibitor bafilomycin on the induction of PDC-E2-specific CTL response in PBC. Importantly, our data indicate that pre-treatment with either lactacystin or bafilomycin inhibits the PDC-E2 immune complex-induced CTL response. The processing and presentation of PDC-E2 by CD8(+)T cells is mediated by proteasomes and facilitated by Fcgamma receptor-mediated endocytosis. This data reflects another layer of interaction between components of the immune system in the development of autoimmunity. Further characterization of autoantigen uptake and processing may lead to potential therapeutic intervention.

Acetylcysteine↗
PubMed2003

Frequencies of interferon-gamma and interleukin-10 secreting cells in peripheral blood mononuclear cells and liver infiltrating lymphocytes in chronic hepatitis B virus infection.

Cytokine balance may play an important role in effective antiviral immunity. We determined the frequencies of interferon-gamma (IFN-gamma)-, interleukin-4 (IL-4)-, and interleukin-10 (IL-10)-secreting cells in response to HBV antigens in peripheral blood mononuclear cells (PBMCs) and liver-infiltrating lymphocytes (LILs) using an enzyme-linked immuno spot (ELISpot) assay and related them to serum ALT and HBV DNA levels, and hepatic histological findings. PBMCs were obtained from 25 patients with chronic hepatitis B, from eight of whom LILs were also obtained, and 12 healthy controls. On stimulation with hepatitis B core antigen (HBcAg), the median (range) frequencies of IFN-gamma- and IL-10-secreting cells were 25 (7-71) and 54 (26-101) cells/10(4) PBMCs, respectively, in patients with chronic hepatitis B, and 4 (0-12) and 36 (7-63) cells/10(4) PBMCs, respectively, in healthy controls. The frequencies of HBcAg-specific IFN-gamma-secreting cells in PBMCs and LILs of chronic hepatitis B patients correlated with serum ALT levels. Those of LILs correlated with serum ALT levels and HAI scores. In conclusion, HBcAg-specific IFN-gamma-secreting cells may play a role in liver damage in chronic HBV infection. Excessive IL-10 production by PBMCs and LILs in response to HBcAg may suppress antiviral immune responses and contribute to persistent infection.

Journal Article↗
PubMed2003

Role of Valpha 14 NKT cells in the development of impaired liver regeneration in vivo.

Although we have previously demonstrated that IL-12 stimulation increases the number of hepatic natural killer (NK) T (NKT) cells and enhances liver injury during the early phase of liver regeneration, the role of NKT cells has remained unknown. We therefore evaluated the influence of NKT cells activated by IL-12 or by alpha-galactosylceramide (alpha-GalCer) on murine liver regeneration using Valpha 14 NKT knockout (Jalpha 281(-/-)) mice. Levels of serum alanine aminotransferase (sALT) 24 hours after partial hepatectomy were enhanced in Jalpha 281(+/+) but not in Jalpha 281(-/-) mice by both procedures. Hepatic NKT cells expressed considerably more interferon (IFN) gamma and tumor necrosis factor alpha (TNF-alpha) messenger RNA (mRNA) after stimulation with both factors in Jalpha 281(+/+) mice. Either anti-IFN-gamma or TNF-alpha antibody inhibited the enhancement of liver injury. Furthermore, recombinant TNF-alpha injection similarly caused injury in hepatectomized livers of both Jalpha 281(+/+) and Jalpha 281(-/-) mice; indeed, adoptively transferred TNF-alpha(+/+) NKT cells enhanced liver injury after hepatectomy in TNF-alpha knockout mice. TNF receptor expressions on hepatocytes increased and peaked 24 hours after partial hepatectomy. In conclusion, simultaneous TNF-alpha synthesis and high levels of TNF receptor expression on hepatocytes cause severe liver damage by activated NKT cells during liver regeneration.

Animals↗
PubMed2002

Differential effect of cytotoxic T lymphocyte variant epitopes on generation and cytotoxicity in chronic hepatitis C virus infection.

Human leukocyte antigen (HLA) B44-restricted, hepatitis C virus (HCV)-specific cytotoxic T lymphocytes (CTLs) recognize HCV nucleoprotein amino acid residues 88-96 as an epitope. We previously reported the existence of variant peptide sequences at the epitope locus in three of 27 patients with HCV infection and HLA B44. Here we studied the effects of the variant peptide sequences on generation and cytotoxicity of CTLs. Two of the three variant peptides generated CTLs poorly although they activated well the cytotoxicity of CTLs. Such a differential activation of proliferation and cytotoxicity may contribute to the emergence of HCV with variant epitopes for CTLs.

Journal Article↗
PubMed2002

Contrast-enhanced endoscopic ultrasonography improves the preoperative localization of insulinomas.

We report a case in which endoscopic ultrasonography (EUS), intraductal ultrasonography (IDUS) and contrast-enhanced EUS using Levovist helped to localize insulinoma correctly. A 74-year-old woman complained of symptomatic fasting hypoglycemia with relatively high concentration of serum insulin level. Dynamic contrast-enhanced computed tomography revealed a small tumor of 8 mm diameter in the pancreatic head. Insulin secretion was strongly stimulated by calcium injection into the gastroduodenal artery. To clarify the precise localization, we performed EUS, IDUS and contrast-enhanced EUS. The tumor was enhanced clearly by Levovist, and the distance from the main pancreatic duct was more than 3 mm. Therefore, a preoperative decision could be made to use the enucleation method for resection of the tumor. The surgeon could enucleate the tumor in a brief operation according to the preoperative diagnosis, and serum glucose levels returned to normal range after the operation. Contrast-enhanced EUS using Levovist was shown to be a useful diagnostic method for precise localization of small insulinoma.

Aged↗
PubMedDate not supplied

Clinical significance in molecular detection of p53 mutation in serum of patients with colorectal carcinoma.

Circulating DNA can be isolated from serum of patients with various carcinomas and p53 mutation can be observed in colorectal carcinoma. The aim of this study was to investigate the correlation between p53 mutation in DNA extracted from colorectal carcinoma and that in DNA extracted from serum of patients with colorectal carcinoma. The clinical significance in molecular detection of p53 mutation in serum of patients with colorectal carcinomas was also investigated. DNA was extracted from tumors and non-tumorous colorectal tissues of 46 patients with single sporadic colorectal carcinomas of stage I (n=6), stage II (n=18), stage III (n=15), and stage IV (n=7) according to the TNM classification. Circulating DNA was also extracted from the serum of the 46 patients with colorectal carcinoma and from 7 healthy volunteers for normal control. Mutations of the p53 gene were analyzed using a fluorescence-based polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) method. DNA sequences were determined in DNA fragments with shifted peaks by SSCP methods. Mutations in tumors were found in 22 (48%) of 46 patients, and mutations in serum were found in 3 (14%) of these 22 patients. Of 4 patients with stage IV disease, 3 (75%) had serum p53 mutation and the mutation pattern of these 3 patients was the same in both tumor and serum. No correlation was seen between p53 mutation in serum and the level of serum DNA. There was no significant difference between the presence of p53 mutation in serum and tumor size, depth of invasion, vascular invasion, or lymph node metastasis. However, liver metastasis showed significant difference (p=0.0026). The presence of p53 mutation in serum was associated with a clinically advanced stage accompanied by liver metastasis.

Adult↗
PubMedDate not supplied

Increased tyrosine kinase activites may lead to the phenotypic differences of gastric cancer cells.

BACKGROUND: The aim of this study was to elucidate possible mechanisms responsible for the phenotypic difference in gastric cancer cells between the intestinal type and the diffuse type. MATERIALS AND METHODS: The gastric cancer cell lines MKN7 and KATO-III were used. Expression of adhesion molecules and protein tyrosine phosphorylation were examined by immunoblotting. Protein-protein interactions were determined by immunoblotting following immunoprecipitation. ERK activity was assessed by immunoblotting using anti-phospho-ERK antibody. RESULTS: E-cadherin expression in KATO-III was decreased compared to that in MKN7. The expression of alpha-, beta- and gamma-catenin was not significantly different; beta- and gamma-catenin were highly tyrosine phosphorylated in KATO-III but not in MKN7. In KATO-III, a number of tyrosine phosphorylated proteins, including extracellular signal-regulated protein kinases (ERKs) and epidermal growth factor receptor (EGFR), were observed irrespective of EGF stimulation and induction of ERK activity and EGFR tyrosine phosphorylation by EGF were less than that in MKN7. CONCLUSION: Increased tyrosine kinase activities may cause diminished expression of E-cadherin and tyrosine phosphorylation of catenins, resulting in the abrogated cell-cell adhesion in gastric cancer cells.

Cadherins↗
PubMedDate not supplied

Cytidine-phosphate-guanosine oligodeoxynucleotides and interferon-alpha-expressing tumor cells effectively induce dendritic cell maturation in vitro.

BACKGROUND: Dendritic cells (DCs) play an important role in immune response and cytidine-phosphate-guanosine (CpG) oligodeoxynucleotides (ODN) as well as interferon (IFN)-alpha have been proven to induce DC maturation. In this study, the synergistic effects of CpG-ODN and IFN-alpha on DC maturation were evaluated. MATERIALS AND METHODS: Surface molecules on DCs and the stimulatory responses of DCs to allogeneic splenocytes were analyzed after cultivation with CpG-ODN and IFN-alpha-overexpressing murine colorectal cancer MC38 cells (MC38-IFNalpha). RESULTS: Co-incubation with CpG-ODN and MC38-IFNalpha, but not wild-type MC38 cells (MC38-WT), effectively up-regulated co-stimulatory molecules on the DCs. CpG, in combination with IFN-alpha, stimulated IL-1beta and TNF-alpha production by DCs effectively. When DCs preincubated with CpG-ODN and MC38-IFNalpha were co-incubated with allogeneic splenocytes in vitro, the proliferation of these splenocytes was significantly enhanced compared with that of splenocytes incubated with CpG-ODN and MC38-WT cells (p = 0.041). CONCLUSION: Since CpG-ODN and IFN-alpha have synergistic effects on DC maturation, they may induce potent antitumor immune responses and combination therapy should be considered for clinical application.

Animals↗