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S Shimada

Publications and source records attributed to S Shimada.

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

Expression of receptor-activity modifying protein (RAMP) mRNAs in the mouse brain.

Receptor activity modifying proteins (RAMPs) comprise a family of accessory proteins for G protein-coupled receptors (GPCRs). They function as receptor modulators that determine the ligand specificity of receptors for calcitonin gene-related peptide (CGRP), amylin and adrenomedullin (ADM). Here we demonstrate for the first time the characteristic distributions of the RAMP family mRNAs in the brain. Northern blot analysis revealed that mRAMP 1 and 3 mRNAs were intensely expressed in the brain, but mRAMP2 mRNA less abundantly. In situ hybridization studies showed the heterogenous and unique distributions of mRAMP mRNAs; RAMP1 mRNA was widely expressed throughout the brain including the cerebral cortex, caudate putamen, amygdaloid complex, hippocampus, cerebellum and ependyma, mRAMP2 was most abundant in the hippocampus, cerebellum, pia mater and blood vessels, while mRAMP3 was specifically distributed in a variety of thalamic nuclei and the cerebellum. In addition, RAMP1 and -3 genes were also detected in the subfornical organ and area postrema, which are members of circumventricular organs lacking blood-brain barrier. The present results help in understanding the diversification and regulation of receptor functions for calcitonin family peptides, and potentially other GPCRs in the brain.

Animals↗
PubMed2001

Discovery of a novel compound: insight into mechanisms for acrylamide-induced axonopathy and colchicine-induced apoptotic neuronal cell death.

The exposure of humans and experimental animals to certain industrial toxins such as acrylamide is known to cause nerve damage classified as axonopathy, but the mechanisms involved are poorly understood. Here we show that acrylamide induces morphological changes and tyrosine phosphorylation of focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (Pyk2), a member of the FAK subfamily, in human differentiating neuroblastoma SH-SY5Y cells. Furthermore, we identified a novel molecule designated 'compound-1' that inhibits the morphological and biochemical events. Daily oral administrations of the compound also effectively alleviated behavioral deficits in animals elicited by acrylamide in inclined plane testing, landing foot spread testing and rota-rod performance testing. The compound also effectively inhibited the biological and biochemical responses caused by another axonopathy inducer, colchicine, including tyrosine phosphorylation of Pyk2, formation of an 85-kDa poly(ADP-ribose)polymerase (PARP) fragment and apoptosis-associated induction of the NAPOR gene as well as neuronal cell death. Our findings not only provide insight into FAK and Pyk2 functions in neuronal cells, but may also be important in the development of therapeutic agents for peripheral neuropathy and neurodegeneration.

Acrylamides↗
PubMed2001

A single amino acid substitution in MDEG2 specifically alters desensitization of the proton-activated cation current.

To clarify functional roles of MDEG2 (mammalian degenerin-2), a modulatory subunit of proton-activated cation channels, in MDEG1/MDEG2 heteromer, we replaced the Gly481 residue in MDEG2 with cysteine or phenylalanine and characterized them electrophysiologically. Expression of MDEG1 in Xenopus oocytes elicited proton-activated cation currents that were rapidly desensitized. Co-expression of MDEG1 and MDEG2 (or MDEG2-G481C) displayed similar current traces as MDEG1 alone. In contrast, co-expression of MDEG1 and MDEG2-G481F dramatically attenuated desensitization of the proton-activated currents. Interestingly, the G481F mutation in MDEG2 did not alter other channel properties including maximal whole-cell currents, ionic selectivity, pH-sensitivity and affinity for amiloride. Thus, Gly481 in MDEG2 specifically controls inactivation process of the MDEG1/MDEG2 channel.

Acid Sensing Ion Channels↗
PubMed2001

Identification of coding single-nucleotide polymorphisms in human taste receptor genes involving bitter tasting.

T2Rs comprise a G-protein-coupled receptor superfamily that contains functionally defined bitter taste receptors. Here we report the tissue expressions and coding single-nucleotide polymorphisms (cSNPs) in human T2R genes (hT2R3, hT2R4, and hT2R5) on chromosome 7q31. We first demonstrated that hT2R3, hT2R4, and hT2R5 are actually expressed in the circumvallate papillae of the human tongue by reverse transcription-polymerase chain reaction (RT-PCR). We identified six cSNPs within the T2R receptor genes. The hT2R4 and hT2R5 contained four and one cSNPs that cause missense mutations, respectively, while hT2R3 included one silent nucleotide mutation. However, we could not find any nonsense mutations that resulted in a frameshift or a premature stop codon within the open reading frames. Genotype frequencies of each cSNP were in Hardy-Weinberg equilibrium. The identification of nucleotide diversity and amino acid polymorphisms in human T2R receptors could help clarify individual differences in the acceptability and sensitivity to bitter compounds.

Base Sequence↗
PubMed2001

Simultaneous determination of taxol and its metabolites in microsomal samples by a simple thin-layer chromatography radioactivity assay--inhibitory effect of NK-104, a new inhibitor of HMG-CoA reductase.

The inhibitory effect of NK-104, a potent inhibitor of HMG-CoA reductase, on taxol metabolism was examined using radio-TLC. This method is described for in vitro measurement of taxol metabolites as an alternative to the commonly used HPLC assay. After incubation of 14C-taxol with human liver microsomes, the supernatants were developed using a solvent system consisting of toluene-acetone-formic acid (60:39:1, v/v) and quantified with a bioimaging analyzer. The described method provides a valuable tool for the simultaneous determination of unchanged taxol and its major metabolites. There was no inhibitory effect of NK-104 on CYP-mediated metabolism of taxol in human liver microsomes.

Antineoplastic Agents, Phytogenic↗
PubMed2001

Frequent p53 mutation in brain (fetal)-type glycogen phosphorylase positive foci adjacent to human 'de novo' colorectal carcinomas.

'de novo' carcinogenesis has been advocated besides 'adenoma carcinoma sequence' as another dominant pathway leading to colorectal carcinoma. Our recent study has demonstrated that the distribution of brain (fetal)-type glycogen phosphorylase (BGP) positive foci (BGP foci) has a close relationship with the location of 'de novo' carcinoma. The aims of the present study are to investigate genetic alteration in the BGP foci and to characterize them in the 'de novo' carcinogenesis. 17 colorectal carcinomas without any adenoma component expressing both immunoreactive p53 and BGP protein were selected from 96 resected specimens from our previous study. Further investigations to examine the proliferating cell nuclear antigen (PCNA)-labelling index, and the p53 and the codon 12 of K-ras mutation using the polymerase chain reaction-single strand conformation polymorphism were performed in the BGP foci, BGP negative mucosa and carcinoma. The BGP foci were observed sporadically in the transitional mucosa adjacent to the carcinoma in all cases. The PCNA labelling index in the BGP foci was significantly higher than that in the BGP negative mucosa (P< 0.001). p53 mutations were observed in 8 carcinomas, but no K-ras mutation was detected. Interestingly, although none of the overexpressions of p53 protein was detected immunohistochemically in the BGP positive foci, the p53 gene frequently (41.2% of the BGP foci tested) mutated in spite of no K-ras mutation. The present study demonstrates potentially premalignant foci in the colorectal transitional mucosa with frequent p53 gene mutation. It is suggested that BGP foci are promising candidates for the further investigation of 'de novo' colorectal carcinogenesis.

Adenoma↗
PubMed2001

Cloning of a lymphatic peptide/histidine transporter.

Although peptide transport across the plasma membrane has been characterized well in the kidney and the intestine, the functional relevance of this transport in other organs has not been addressed. Here we report the cloning of a cDNA for a novel peptide/histidine transporter found in the rat (rPHT2), whose mRNA is expressed mainly in the lymphatic system. rPHT2 encodes a protein of 582 amino acids and showed 49% identity with the brain PHT (PHT1) [Yamashita, Shimada, Guo, Sato, Kohmura, Hayakawa, Takagi and Tohyama (1997) J. Biol. Chem. 272, 10205-10211]. rPHT2 mRNA was abundant in lung, spleen and thymus, and detected faintly in brain, liver, adrenal gland and heart by Northern-blot analysis and reverse transcriptase PCR (RT-PCR). Intense signals for the gene were found in immunocytes using in situ hybridization. Ectopic expression of rPHT2 protein in HEK-293T cells and BHK cells was not found on the cell surface, but was found on the lysosomal membrane using light- and electron-microscopic analysis. Recombinant rPHT2 protein reconstituted into liposomes showed proton-dependent transport activity with histidine and histidyl-leucine. These findings suggest that rPHT2 is involved in the protein catabolic pathway in the lymphatic system.

Amino Acid Sequence↗
PubMed2001

A 14-3-3 protein homologue is expressed in feline enteroepithelial-stages of Toxoplasma gondii.

Fourteen cDNA clones encoding epitopes of proteins of Toxoplasma gondii feline enteroepithelial-stages parasites were isolated and expressed in Escherichia coli in an effort to determine the antigenecity of the parasites. Sequence analysis showed that four of the cDNA clones had a 930-bp open-reading frame encoding a product showing similarity to the 14-3-3 protein mRNA sequence.(1) Southern hybridization of DIG-labeled positive clone with T. gondii genomic DNA cleaved with EcoRI, BamHI and HindIII resulted in one or two bands in each case. In an immunofluorescence assay, polyclonal and monoclonal antibodies raised against the expressed protein showed strong reactivity with feline enteroepithelial-stages parasites and sporozoites. In a complementation assay in which a plasmid carrying the protein-coding region of the isolated cDNA was introduced into a Saccharomyces cerevisiae mutant, strain DS9-22, the expressed protein showed complementation of the function of the 14-3-3 protein in yeast transformants. These findings suggest that T. gondii parasites produce a protein showing partial homology with members of the 14-3-3 protein family and this protein is expressed in feline enteroepithelial-stages parasites.

14-3-3 Proteins↗
PubMed2001

Diffuse brain injury induces local expression of Na+/myo-inositol cotransporter in the rat brain.

We studied expression of an osmoprotective gene, sodium/myo-inositol cotransporter (SMIT) in Marmarou's animal model for human diffuse brain injury by in situ hybridization and immunohistochemistry. In rats with diffuse brain injury, transient upregulation of SMIT mRNA was exclusively observed in the lateral area of pyramidal tract in lower brainstem. The expression was induced at 1 h after injury, peaked at 24 h, and returned to almost control levels at 48 h. Upregulated expression was found mainly in small glia-like cells. By immunohistochemistry using antibodies to phosphorylated mitogen-activated protein (MAP) kinases, inductions of phosphorylated p44/42 MAP kinase were also observed after diffuse brain injury. Interestingly, the distribution patterns of induced phosphorylated p44/42 MAP kinase were completely coincident with those of upregulated SMIT mRNA after diffuse brain injury. These results suggest that diffuse brain injury induces local expression of SMIT by activation of p44/42 MAP kinase cascade. The confined SMIT induction may reflect regional differences of damage and/or cellular differences in sensitivity to neuropathological stresses caused by this injury.

Animals↗
PubMed2001

Prenatal diagnosis of agnathia-holoprosencephaly: three-dimensional imaging by helical computed tomography.

We report a case of agnathia-holoprosencephaly which was prenatally diagnosed based on helical computed tomography (CT) images obtained at 23 weeks of gestation. Ultrasound examination first showed the presence of alobar holoprosencephaly, but the facial structures were not clearly detailed. However, three-dimensional imaging by helical CT precisely demonstrated the most striking feature of agnathia: absence of the mandible. This technique provided us valuable information that contributed to the in utero diagnosis. In utero helical CT is a useful examination tool for the diagnosis of osteogenic abnormalities.

Adult↗
PubMed2001

An accessory role of TCRgammadelta (+) cells in the exacerbation of inflammatory bowel disease in TCRalpha mutant mice.

T cell receptor alpha mutant (TCRalpha (-/-)) mice, which spontaneously develop colitis under conventional conditions, did not show any signs of colitis under germ-free conditions, leaving TCRalpha (-)beta (+) cells (beta (dim) cells) and TCRgamma delta (+) cells much reduced. Moreover, TCRalpha (-/-) mice with alymphoplastic mutation (aly/aly TCRalpha (-/-) mice), which lack Peyer's patches and peripheral lymph nodes, did not suffer from colitis. While both beta (dim) cells and TCRgamma delta (+) cells were present in the colons of aly/aly TCRalpha (-/-) mice and aly/+ TCRalpha (-/-) mice, cytotoxicity of colonic TCRgamma delta (+) cells in aly/aly TCRalpha (-/-) mice was almost abolished. Transfer of TCRgamma delta (+) cells from TCRalpha (-/-) mice into scid/scid mice or aly/aly TCRalpha (-/-) mice could not induce colitis, but injection of anti-TCRdelta mAb into TCRalpha (-/-) mice prevented colitis from developing. Finally, TCRalpha (-/-) mice expressing transgenic (Tg) KN6-TCRgamma delta hardly developed colitis, accompanied by colonization of non-cytotoxic Tg TCRgamma delta (+) cells in their colonic mucosa. These results demonstrate that intestinal resident TCRgamma delta (+) cells may be involved in the exacerbation of inflammatory bowel disease in TCRalpha (-/-) mice.

Animals↗
PubMed2001

Suppression of lens stalk cell apoptosis by hyaluronic acid leads to faulty separation of the lens vesicle.

How the lens vesicle separates normally from the surface ectoderm has not been adequately explained. Apoptosis is an important mechanism that induces tissue development and morphogenesis by physiological cell death during normal development, and hyaluronic acid has been shown to regulate the apoptotic process in various tissues. To elucidate the normal and abnormal processes of lens vesicle separation, we investigated the distribution of apoptotic cells and hyaluronic acid in normal and abnormal lens vesicle development. The offspring from pregnant C57BL/6NJcl mice were removed by laparotomy on days 9, 10, 11, 12, 13, 14, 15, 16 or 18 of gestation. Tissue blocks of the eyes were fixed in 4% paraformaldehyde solution and embedded in paraffin wax. Serial sections of the eye were cut, and sections containing normal lens tissues and spontaneously occurring faulty separation of the lens vesicle were chosen for subsequent procedures. These sections were stained either with TUNEL method for detection of apoptosis or with biotinylated hyaluronic acid binding protein (HABP) for hyaluronic acid. Then TUNEL-positive and HABP-positive reactions in the lens tissues were examined by light microscopy. In normal eye development, the lens stalk connecting the surface ectoderm with the lens vesicle was observed from day 11 through day 12 of gestation, and the lens stalk completely disappeared on day 13 of gestation in this strain. In normally regressive lens stalk, several TUNEL-positive cells were identified, and no positive staining for HABP was seen. However, in spontaneously occurring persistent lens stalk tissues on days 14, 15, 16 and 18 of gestation, no TUNEL-positive cells were detectable, and evident HABP-positive reactions were seen. In eyes on day 12 of gestation with possibly presumed faulty separation of the lens vesicle, no TUNEL-positive cells were detectable and evident HABP-positive reactions were seen in the lens stalk areas. The results indicated that cell death by apoptosis is anatomically closely associated with, appears to be essential for normal regression of the lens stalk, and its failure to occur leads to faulty separation of the lens vesicle. In addition, excessive hyaluronic acid in the lens stalk area may be a possible cause of the lack of apoptosis, inducing its faulty separation.

Animals↗
PubMed2001

Involvement of three or more lymph nodes predicts poor prognosis in submucosal gastric carcinoma.

BACKGROUND: Multivariate analyses has shown that the status of lymph node metastasis and the depth of tumor penetration through the gastric wall are the most important prognostic factors in patients with advanced gastric carcinoma after curative operation. A clinicopathological study was carried out to clarify a simple and optimal prognostic indicator for early gastric cancer. METHODS: Retrospective analyses of 982 patients with early gastric cancer (562 with mucosal [M] and 420 with submucosal [SM] tumor) treated by gastrectomy with D2 lymph node dissection were performed. RESULTS: The incidence of lymph node metastasis from M and SM tumors was 2.5% (14/562) and 20.2% (85/420), respectively. There were no apparent prognostic indicators in patients with M tumors. In patients with SM tumors, the cancer-specific 5-year survival of those with lymph node metastasis was significantly lower than that of those without such metastasis (77.6% vs 98.2%; P < 0.001). An sharp decrease in survival was seen between patients with two positive nodes and those with three positive nodes, and the cancer-specific 5-year survival rate of patients with three or more metastatic lymph nodes was significantly lower than that of those with one or two nodes (P < 0.001; univariate analysis). Multivariate analysis revealed that the involvement of three or more lymph nodes was the sole independent prognostic determinant (P = 0.016); the level of nodal metastasis was not an independent prognostic factor (P = 0.384). All patients with N2 lymph node echelons (according to the Japanese Research Society for Gastric Cancer classification of the draining lymph nodes of the stomach) in the group with one or two positive nodes survived for more than 5 years. CONCLUSION: The sole independent prognostic factor in SM gastric cancer is the involvement of three or more metastatic lymph nodes. We suggest that this simple prognostic indicator for the follow-up of early gastric cancer, and this could lead to potentially effective adjuvant chemotherapy.

Adult↗
PubMed2001

Gastric and intestinal phenotypes of gastric carcinoma with reference to expression of brain (fetal)-type glycogen phosphorylase.

PURPOSE: Although reports have suggested that differentiated gastric carcinomas have different phenotypes, i.e., gastric and intestinal type, this classification is complicated and can be confusing. Our previous studies have demonstrated a close relationship between carcinogenesis in differentiated-type gastric cancer and the expression of brain (fetal)-type glycogen phosphorylase (BGP). The purpose of this study was to investigate the relationship between the mucin phenotype of gastric carcinoma and BGP expression. METHODS: Ninety-six specimens of gastric carcinoma were studied using specific anti-BGP antibody. Correlation of BGP expression with intestinal and gastric phenotypes was determined with the anti-mucin antibodies, HGM, CD10, and MUC2. RESULTS: BGP was expressed in 82.6% (38/46) of differentiated type and in 24.0% (12/50) of undifferentiated type carcinomas. The incidence of BGP positivity was significantly greater in the differentiated-type carcinoma than in the undifferentiated type (P < 0.001). The proportions of gastric, mixed and intestinal types in differentiated and undifferentiated gastric carcinomas were 13.0%, 47.8%, and 39.2%, and 56.0%, 32.0%, and 12.0%, respectively. In both differentiated and undifferentiated types, the phenotype of gastric and intestinal mucin expression corresponded very well with BGP expression, that is, more than 90% of carcinomas with gastric type did not express BGP, whereas approximately 90% of carcinomas with intestinal type did express BGP. CONCLUSIONS: The classification of gastric and intestinal phenotypes of gastric carcinoma in terms of BGP expression was simpler and clearer than such classification in terms of mucin immunohistochemistry. It is suggested that BGP is a useful biomarker for the classification of intestinal and gastric type carcinoma of the human stomach, including classification from the carcinogenetic point of view.

Carcinoma↗
PubMed2001

A new procedure of percutaneous microwave coagulation therapy under artificial hydrothorax for patients with liver tumors in the hepatic dome.

Percutaneous microwave coagulation therapy (PMCT) has been widely used as an effective minimal invasive therapy for small liver tumors. The occurrence of a sonographic masked space due to the presence of the lung, however, has become a major obstacle to visualizing the whole tumor in the hepatic dome. To facilitate the use of PMCT for liver tumors in the hepatic dome, we developed PMCT in combination with the artificial hydrothorax method (percutaneous transdiaphragmatic MCT: PTD-MCT). Our new approach for PMCT to the hepatic tumors located in Couinaud's segments VIII or VII just under the diaphragm resulted in a successful treatment. The separation of the lung from the diaphragm by the infusion of saline into the pleural cavity enabled us not only to visualize the whole tumor in the hepatic dome to accurately target the tumor, but also helped us to avoid injuring the lung. PTD-MCT is therefore strongly recommended for the treatment of liver tumors in the hepatic dome.

Aged↗
PubMed2001

Usefulness of stable HbA(1c) for supportive marker to diagnose diabetes mellitus in Japanese subjects.

To evaluate the adequacy and usefulness of the stable glycated hemoglobin (HbA(1c)) value of 6.5% suggested by the Japan Diabetic Society in 1999 for supportive diagnostic marker of diabetes, we assessed the sensitivity and specificity of an HbA(1c) value of 6.5% in patients who were newly diagnosed by the 75 g oral glucose tolerance test (75g-OGTT). A total of 866 Japanese subjects underwent the 75g-OGTT and HbA(1c) measurement (normal range: 4.3-5.8%). They were divided into three groups [normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and diabetes mellitus (DM)], using the WHO criteria, since no subject with impaired fasting glycemia (IFG) was observed. The cut-off value of HbA(1c) separating DM from NGT or DM from IGT on cumulative distribution curve analysis was 5.9% (sensitivity 0.76 and specificity 0.86) and 5.9% (sensitivity 0.76 and specificity 0.77), respectively. The sensitivity of an HbA(1c) of 6.5% for separation of DM from NGT or IGT by the same analysis was 0.49 and 0.49, respectively. Similarly, the specificity for separation of DM from NGT or IGT was 0.98 and 0.98, respectively. These results mean that 49% of diabetic subjects show an HbA(1c)> or =6.5%, and 51% have an HbA(1c) less than 6.5%, while only 2% of NGT and IGT subjects have an HbA(1c)> or =6.5%, and 98% have a value less than 6.5%. Therefore, the sensitivity of an HbA(1c) value of 6.5% in separating DM from NGT or IGT is low, and thus 6.5% is too high value to use when screening for diabetes. However, the specificity is very high, so an HbA(1c) of 6.5% is a useful supportive marker to diagnose diabetes.

Adult↗
PubMed2001

Massive intravenous immunoglobulin treatment in women with four or more recurrent spontaneous abortions of unexplained etiology: down-regulation of NK cell activity and subsets.

PROBLEM: The aims of this study were to investigate the efficacy of massive intravenous immunoglobulin (MIVIg) treatment for women with recurrent spontaneous abortion (RSA) of unexplained etiology, and to investigate changes in peripheral natural killer (NK) cell activity and subsets. METHOD OF STUDY: MIVIg treatment was performed in 18 pregnancies from 15 women with 4 or more consecutive RSA of unexplained etiology. NK cell activity and subsets were assessed in 8 of the pregnancies. RESULTS: 14 pregnancies resulted in live births and 4 resulted in abortions with chromosome abnormality. The pre-infusion NK cell activity (mean + SD. 40.9 + 17.0%) at 4.4 +/- 0.5 weeks of gestation (GW) decreased to 15.0 +/- 7.90% at post-infusion status (5.4 +/- 0.5 GW). Pre-infusion percentages of CD56+ CD16- cells (3.5 +/- 2.1%) and CD56+ CD16- cells (16.8 +/- 8.8%) decreased to 3.0 +/- 2.2% and 11.1 +/- 6.9%, respectively, after MIVIg treatment. CONCLUSIONS: MIVIg treatment was effective in all 14 pregnancies from RSA women of unexplained etiology, excluding 4 abortions with chromosome abnormality. Peripheral NK cell activity and subsets were suppressed by MIVIg treatment.

Abortion, Habitual↗