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Biomedical subjects

M Shibahara

Publications and source records attributed to M Shibahara.

11 recordsLinked to original sources
PubMed2002

Dermatitis herpetiformis in Japan: an update.

BACKGROUND: Although dermatitis herpetiformis (DH) is a relatively common disease in Caucasian populations, it is rare in Asian populations including the Japanese. We encountered a Japanese case of DH which showed granular IgA and C3 deposits in the papillary dermis and which was associated with gluten-sensitive enteropathy but no HLA-B8/DR3/DQ2. OBJECTIVE: The purpose of this study is to describe the characteristics of Japanese DH cases, since most of them have been reported in Japanese language and dermatologists outside Japan are not familiar with the characteristics of Japanese DH. METHODS: We have reviewed all 34 Japanese DH cases reported previously. RESULTS: We found several features of Japanese DH compared with Caucasian DH, such as a high frequency of the fibrillar pattern, rarity of gluten-sensitive enteropathy and an absence of the HLA-B8/DR3/DQ2 haplotype. CONCLUSION: There might be significant differences in pathophysiology between Caucasian and Japanese DH cases.

Biopsy, Needle↗
PubMed2001

Mannosylerythritol lipid induces characteristics of neuronal differentiation in PC12 cells through an ERK-related signal cascade.

Rat pheochromocytoma PC12 cells undergo neuronal differentiation in response to nerve growth factor (NGF). The differentiation involves protein kinase cascades that include the kinases MEK and ERK, as well as activation of the transcription factors c-Jun and c-Fos. We show here, that exposure of PC12 cells to mannosylerythritol lipid (MEL), a yeast extracellular glycolipid, enhances the activity of acetylcholinesterase and interrupts the cell cycle at the G1 phase, with resulting outgrowth of neurites and partial cellular differentiation. Treatment with MEL stimulates the phosphorylation of ERK to a similar extent as treatment with NGF, although, the appearance of phosphorylated ERK is somewhat delayed. Both the MEL-induced outgrowth of neurites and the increase in the activity of acetylcholinesterase are prevented by PD98059, a specific inhibitor of MEK. Northern blotting analysis of c-jun transcripts and analysis of transcription in PC12 cells of a c-jun/CAT reporter construct demonstrated a significant increase in the rate of transcription of the c-jun gene upon treatment with MEL. The sequence elements required for the MEL-mediated activation of transcription of the c-jun gene are located between nucleotides -126 and -79 in the 5' flanking region. Our results suggest that MEL induces characteristics of neuronal differentiation in PC12 cells, with transactivation of the c-jun gene, via an ERK-related signal cascade that is partially overlapping the pathways activated in response to NGF. These results might provide the groundwork for the use of microbial extracellular glycolipids as novel reagents for the treatment of cancer cells.

Acetylcholinesterase↗
PubMed2001

Involvement of nitric oxide in chondrocyte cell death in chondro-osteophyte formation.

OBJECTIVE: To examine the nitric oxide (NO) production relevant to chondrocyte cell death in order to elucidate the mechanism of chondro-osteophyte formation in osteoarthrotic joints. DESIGN: Human chondro-osteophytes were obtained during total hip arthroplasty. Expression of inducible nitric oxide synthase (iNOS) mRNA was determined by in-situ hybridization. Localization of iNOS and nitrotyrosine at protein level were examined by immunohistochemistry. Cell death of chondrocytes were confirmed by both TUNEL method and transmission electron microscopy. RESULTS: The various populations of proliferative and hypertrophic chondrocytes expressed iNOS mRNA and iNOS as well as nitrotyrosine protein. Approximately 30% of hypertrophic chondrocytes forming chondro-osteophyte showed positive reaction to TUNEL staining. Electron microscopy confirmed both disintegrated and apoptotic chondrocytes in these zones. In the deep hypertrophic zone calcification was seen around each of the matrix vesicles and some masses of cell debris. CONCLUSION: Chondro-osteophyte formation involves NO production by chondrocytes. The expression and localization of iNOS and nitrotyrosine in chondro-osteophytes suggest the significant role of NO in chondrocyte hypertrophy and apoptosis.

Aged↗
PubMed2000

CD44 expression in soft tissue sarcomas.

Recent studies have shown that expression of alternatively splicing variants of CD44 is correlated with prognosis for several kinds of malignant tumors. However, little is known about the expression of CD44 standard and variant isoforms in soft tissue sarcomas. In this study 47 cases of soft tissue sarcoma [18 malignant fibrous histiocytomas (MFHs), 13 synovial sarcomas (SSs), 7 malignant schwannomas (MSs), and 9 liposarcomas (LSs)] were examined immunohistochemically. The monoclonal antibodies to the standard form of CD44 (CD44H) and variant exons of CD44v3, 4, 5, 6, 7, 9, and v10 were used. We analyzed the membranous expression pattern of CD44H and CD44 variant exons and assessed the relation between expression of CD44s and metastasis-free survival rates (MFSR) of patients with soft tissue sarcoma. A few sarcomas expressed CD44v3 (2/47) and v7 (2/47), but none of the sarcomas expressed CD44v10. CD44v4 (5/47), v5 (4/47), v6 (10/47), and v9 (9/47) are relatively common types of variant isoforms in soft tissue sarcomas. Expression of CD44v6 is more frequently detected in high-grade than in low-grade tumors. CD44v6 or CD44v9 expression was correlated with metastasis-free survival of patients with soft tissue sarcomas.

Adolescent↗
PubMed2000

Increased osteocyte apoptosis during the development of femoral head osteonecrosis in spontaneously hypertensive rats.

We investigated the presence of osteocyte apoptosis in the necrotic trabeculae of the femoral head of spontaneously hypertensive rat (SHR) using the in situ nick end labeling (TUNEL) method and transmission electron microscopy. The occurrence of osteonecrosis and ossification disturbance was significantly higher in SHR compared with Wistar Kyoto (WKY) rats, and Wistar (WT) rats used as control animals (P < 0.01). A high population of TUNEL positive osteocytes was detected mainly in 10- and 15-week-old SHRs. Sectioned examination of the femoral head of SHRs and WKY rats by electron microscopy revealed apoptotic cell appearances such as aggregation of chromatin particles and lipid formation. In contrast, a positive reaction was significantly lower in osteocytes in the femoral heads of WT rats (P < 0.01). Our results indicate that apoptosis forms an important component of the global pathologic process affecting the femoral head of SHR, which leads to osteonecrosis in this region.

Animals↗
PubMed1999

Mannosylerythritol lipid is a potent inducer of apoptosis and differentiation of mouse melanoma cells in culture.

Malignant melanomas are tumors that are well known to respond poorly to treatment with chemotherapeutic reagents. We report here that mannosylerythritol lipid (MEL), an extracellular glycolipid from yeast, markedly inhibited the growth of mouse melanoma B16 cells in a dose-dependent manner. Exposure of B16 cells to MEL at 10 microM and higher concentrations caused the condensation of chromatin, DNA fragmentation, and sub-G1 arrest, all of which are hallmarks of cells that are undergoing apoptosis. Analysis of the cell cycle also suggested that both the MEL-mediated inhibition of growth and apoptosis were closely associated with growth arrest in the G1 phase. Moreover, MEL exposure stimulated the expression of differentiation markers of melanoma cells, such as tyrosinase activity and the enhanced production of melanin, which is an indication that MEL triggered both apoptotic and cell differentiation programs. Forced expression of Bcl-2 protein in stably transformed B16 cells had a dual effect: it interfered with MEL-induced apoptosis but increased both tyrosinase activity and the production of melanin as compared with these phenomena in vector-transfected MEL-treated control B16 cells. These results provide the first evidence that growth arrest, apoptosis, and the differentiation of mouse malignant melanoma cells can be induced by a microbial extracellular glycolipid.

Animals↗
PubMed1999

Expression of CD44 variants in osteosarcoma.

The standard form of CD44 (CD44H) is a transmembranous glycoprotein, widely distributed on a variety of human lymphoid cells, epithelial cells and tumours. CD44 has many variant forms, which are generated by alternative splicing. In recent years, CD44 has been reported to be related to the degree of tumour differentiation, tumour cell invasion, and metastasis. We investigated 44 tumour specimens in 39 patients with osteosarcoma immunochemically to analyse the expression of CD44 standard (CD44H) and variant exon-encoded gene products (CD44v3, v4, v5, v6, v7, v9, and v10). Furthermore, the relationship between CD44 expression and the clinical outcome of patients with osteosarcoma was analysed. Membrane accentuation and exclusive cytoplasmic reactivity were analysed as separate staining patterns. Tumour cells and some multinucleated giant cells were markedly stained. CD44H, v3, v4, v5, v6, v7, v9, and v10 were expressed in 85%, 49%, 54%, 59%, 46%, 5%, 28%, and 10% of the specimens respectively. The cumulative 5-year metastasis-free survival was 58% in CD44v6-negative cases and 24% in CD44v6-positive cases (P=0.046). However, the cumulative 5-year metastasis-free survival was not significantly different between cases positive and negative for other variants of CD44. Multivariate analysis (Cox proportional-hazard model) with CD44v6 expression (positive or negative), chemotherapy (intensive or non-intensive), tumour site (proximal or distal), and age (at least 30 years or less than 30 years) showed that expression of CD44v6 and chemotherapy were important prognostic factors in patients with osteosarcoma. Overexpression of CD44 isoforms containing variant v6 is correlated with poor prognosis in patients with osteosarcoma.

Adolescent↗
PubMed1999

Structure, tissue distribution, and pharmacological characterization of Xenopus orexins.

We isolated the Xenopus gene encoding prepro-orexin to predict the structures of orexins in submammalian chordates. Putative mature Xenopus orexin-A and -B are highly similar to each mammalian counterpart. Especially, the C-terminal 10 residues were highly conserved among these species and isopeptides. Immunohistochemical examination of Xenopus brain revealed that orexin-containing neurons were highly specifically localized in the ventral hypothalamic nucleus. A rich network of immunoreactive fibers was found in various regions of the Xenopus brain. The distribution was similar to that of mammalian orexins. Xenopus orexin-A and -B specifically bind and activate human orexin receptors expressed in Chinese hamster ovary cells. Of interest, Xenopus orexin-B had several-fold higher affinity to human OX2R compared with human orexins. These results suggest that Xenopus orexin-B might be a useful pharmacological tool as an OX2R selective high-affinity agonist.

Amino Acid Sequence↗
PubMed1990

Composition of long-chain bases in sphingomyelin of the guinea pig Harderian gland.

Sphingomyelin from the guinea pig Harderian gland was isolated and characterized. The purified sphingomyelin gave a broad spot on thin-layer chromatography. The fatty acid composition of the whole sphingomyelin was 71% nonhydroxy acids and 29% 2-hydroxy acids. Methyl-branched fatty acids were only 2% of the total acids. The long-chain bases were composed of straight-chain sphingenines (50%) and sphinganines (6%). Methyl-branched long-chain bases were 44% of the bases. The sphingomyelin was further separated into four fractions (I, II, III, IV) by high-performance liquid chromatography. The ratio of fractions I, II, III, and IV was approximately 2:5:2:1, respectively. The fatty acids of fractions I and II consisted of nonhydroxy acids and those of fractions III and IV were 2-hydroxy acids. The long-chain bases of fractions I and III were sphinganines including 10-, 9-, and 8-methylsphinganines and anteiso-sphinganines. These methyl-branched bases occupied about 70% of the total sphinganines. The long-chain bases of fractions II and IV consisted of sphingenines. The methyl-branched unsaturated bases were only 30% of the total sphingenines, all in the anteiso-form. Thus, the sphingomyelin obtained from guinea pig Harderian gland had complex compositions of fatty acids and long-chain bases, and half the number of long-chain bases had methyl branches. The methyl-branched fatty acids were only a minor component. These characteristics are similar to those of cerebrosides isolated from the same source.

Animals↗