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Biomedical subjects

Y Kohgo

Publications and source records attributed to Y Kohgo.

At least 19 recordsLinked to original sources
PubMed2000

Overexpression of hemochromatosis protein, HFE, alters transferrin recycling process in human hepatoma cells.

HFE is a MHC class 1-like protein that is mutated in hereditary hemochromatosis. In order to elucidate the role of HFE protein on cellular iron metabolism, functional studies were carried out in human hepatoma cells (HLF) overexpressing a fusion gene of HFE and green fluorescent protein (GFP). The expression of HFE-GFP was found to be localized on cell membrane and perinuclear compartment by fluorescent microscopy. By co-immunoprecipitation and Western blotting, HFE-GFP protein formed a complex with endogenous transferrin receptor and beta(2)-microglobulin, suggesting that this fusion protein has the function of HFE reported previously. We then examined the (59)Fe uptake and release, and internalization and recycling of (125)I-labeled transferrin in order to elucidate the functional roles of HFE in the cell system. In the transfectants, HFE protein decreased the rate of transferrin receptor-dependent iron ((59)Fe) uptake by the cells, but did not change the rate of iron release, indicating that HFE protein decreased the rate of iron influx. Scatchard analysis of transferrin binding to HFE-transfected cells showed an elevation of the dissociation constant from 1.9 to 4. 3 nM transferrin, indicating that HFE protein decreased the affinity of transferrin receptor for transferrin, while the number of transferrin receptors decreased from 1.5x10(5)/cell to 1. 2x10(5)/cell. In addition, the rate of transferrin recycling, especially return from endosome to surface, was decreased in the HFE-transfected cells by pulse-chase study with (125)I-labeled transferrin. Our results strongly suggest an additional role of HFE on transferrin receptor recycling in addition to the decrease of receptor affinity, resulting in the reduced cellular iron.

Carcinoma, Hepatocellular↗
PubMed2000

Inhibition of food intake by central injection of anti-orexin antibody in fasted rats.

It has been shown that intracerebroventricular injection of synthetic orexins stimulated food intake in rats. This pharmacological evidence suggests that orexins may have a role for the central regulation of feeding. In the present study, we investigated the hypothesis of whether endogenous orexins indeed play a vital role in feeding behavior. An anti-orexin polyclonal antibody was used throughout the study. First, we examined the specificity of the antibody to orexin by Western blot analysis and immunohistochemistry. Next, the effects of central injection of the orexin antibody on food intake in 24-h-fasted rats were evaluated. Western blot analysis revealed that the orexin antibody detected synthetic orexin-A. Immunohistochemical study showed that orexin-positive neurons were identified only in the lateral hypothalamic area, in agreement with previous reports. Neither control antibody nor the orexin antibody preabsorbed with excess amount of orexin-A detected neurons, indicating that the orexin antibody is specific. Intracisternal but not intraperitoneal injection of the orexin antibody dose-dependently suppressed feeding. All these results suggest that immunoneutralization of endogenous orexins in the brain reduced food intake. In other words, we suggest that endogenous brain orexin may have a physiologically relevant action on feeding behavior.

Animals↗
PubMed2000

Morphogenesis of nonpolypoid colorectal adenomas and early carcinomas assessed by cell proliferation and apoptosis.

Nonpolypoid neoplasms, as well as ordinary polypoid tumours, are occasionally found in the colorectum. To clarify whether cell kinetic status affects the macroscopic morphology of colorectal neoplasms, we investigated proliferative indices (PI), apoptotic indices (AI), and the expression of apoptosis-related gene products. We examined 110 colorectal neoplasms comprised of 36 polypoid, 38 flat elevated and 36 depressed tumours. According to WHO's criteria these tumours consisted of 61 adenomas with low grade dysplasia (LGD), 30 adenomas with high grade dysplasia (HGD) and 19 carcinomas with submucosal invasion. Apoptotic cells were detected by TUNEL staining. Proliferating cells and apoptosis-related gene products were assessed by immunohistochemistry for Ki-67, p53, Bcl-2, and Bax antigens. AI were closely associated with macroscopic morphology in adenomas but not in carcinomas. PI were relatively constant among the three macroscopic types in adenomas and carcinomas. Median AI values of polypoid, flat elevated and depressed tumours were 1.8%, 2.1% and 4.6% for adenomas with LGD, 0.8%, 2.4% and 6.2% for adenomas with HGD and 2.9%, 4.0% and 3.6% for carcinomas, respectively. Overall PI were significantly higher in carcinomas than in adenomas with LGD, whereas AI were not different. Although the incidence of expression was significantly higher in carcinomas for p53 and in adenomas for Bcl-2 than the others, the expression of apoptosis-related gene products (p53, Bcl-2 and Bax) was similar among polypoid, flat elevated and depressed tumours. Macroscopic morphology of colorectal adenomas is determined by the apoptosis not by proliferation, and high apoptosis found in depressed adenomas implies their low net growth.

Adenoma↗
PubMed2000

Immunochemical characterization of monoclonal protein in the serum of a patient with Waldenstr]om's macroglobulinemia showing both pyroglobulin and cryoglobulin properties.

A patient with Waldenstr]om's macroglobulinemia whose serum demonstrated properties of both pyroglobulin and cryoglobulin was studied. A monoclonal (M) protein in the serum of the patient was identified by immunoelectrophoresis (IEP) and immunofixation electrophoresis (IFE) as IgM-lambda. The M-protein was separated by gel permeation high-performance liquid chromatography (HPLC). Cryoglobulin in the serum was isolated by the method of cold precipitation. The cryoglobulin was identified as IgM-lambda type by IEP and was the same M-protein as that which occurred in this patient's serum. The purified cryoglobulin also had the properties of a pyroglobulin. Neither property disappeared following pretreatment with 2-mercaptoethanol (2-ME), urea, and Triton X-100 detergent, and deglycosylation with N-glycanase (E.C. 3.5.1.52). We suggest that these abnormal properties were caused by the molecular abnormality of the IgM-lambda M-protein.

Aged↗
PubMed2000

Expression of glucocorticoid receptor beta in lymphocytes of patients with glucocorticoid-resistant ulcerative colitis.

BACKGROUND & AIMS: Recently, the glucocorticoid receptor beta (hGRbeta) was suggested to play a role as a dominant negative regulator for determining glucocorticoid response. The aim of this study was to clarify whether reverse-transcription polymerase chain reaction (RT-PCR) analysis of hGRbeta messenger RNA (mRNA) can predict the response to glucocorticoids in patients with ulcerative colitis. METHODS: Total RNA obtained from peripheral blood mononuclear cells (PBMCs) of 23 patients with ulcerative colitis and 20 healthy volunteers was reverse transcribed; the resulting complementary DNA was amplified using specific primers for hGRalpha and hGRbeta. Protein expression of hGR in PBMCs was confirmed by immunoprecipitation-Western blot analysis. RESULTS: The expression of hGRalpha mRNA (477 base pairs) was detected in all patients and all healthy volunteers. In contrast, a hGRbeta mRNA (366 base pairs) was detected in 1 (9.1%) of 11 glucocorticoid-sensitive patients, 10 (83.3%) of 12 glucocorticoid-resistant patients, and 2 (10%) of 20 healthy volunteers. The positive rate of hGRbeta mRNA in the resistant group was significantly higher than that in the sensitive group (P = 0.0019). The hGRbeta band could be detected by immunoprecipitation-Western blotting in hGRbeta mRNA-positive patients. CONCLUSIONS: The results show that the expression of hGRbeta mRNA in PBMCs examined by RT-PCR may serve as a novel predictor of glucocorticoid response in ulcerative colitis.

Adolescent↗
PubMed2000

Fas-mediated apoptosis of peripheral blood mononuclear cells in patients with hepatitis C.

In the present study, we demonstrated that a close relationship exists between hepatitis C virus (HCV) infection of peripheral blood mononuclear cells (PBMCs) and cell-surface Fas expression in patients with hepatitis C, and showed the possibility of PBMCs apoptosis via a Fas-mediated system. The expression of Fas on PBMCs was found by flowcytometric analysis to be significantly increased in these patients. In addition, the treatment of patients' PBMCs with anti-Fas antibody induced cell death, with nuclear condensation and fragmentation and cellular DNA fragmentation. These data indicate that the patients' PBMCs expressed a large amount of functional Fas on the cell surface and were susceptible to stimulation against Fas, causing apoptotic cell death. We then quantified the serum-soluble Fas ligand (sFasL), which was known to bind to Fas and induce the apoptotic signals into the sensitized cells. The patients' serum sFasL levels were significantly higher than those of normal subjects and showed a good negative correlation with their PBMC number. To demonstrate the correlation between Fas expression and HCV infection, nested reverse transcriptase polymerase chain reaction (RT-PCR) was performed to detect HCV RNA. Interestingly, HCV RNA was preferentially detected from Fas-positive cells but not from Fas-negative cells, which had been isolated from PBMCs by magnetic beads. These results suggest that HCV infection of PBMCs might induce Fas expression and additional stimulation such as sFasL might induce apoptosis in these Fas-expressing cells. These mechanisms, in addition to hypersplenism, may explain the decrease in the number of PBMCs observed in patients with chronic hepatitis C.

Adult↗
PubMed2000

Temporary use of an accuflex stent for unextractable common bile duct stones.

Endoscopic management has become the main therapeutic approach for the extraction of common bile duct (CBD) stones, and successful removal can be achieved in 80-90% patients using conventional balloon and basket techniques. However, if it is difficult to completely fragment a stone, or to clear the CBD, which may occur for a variety of reasons, the therapeutic problem will remain. When bile duct stones can not be removed, a viable management option is to place a biliary stent to ensure drainage. However, recent studies of long-term biliary stenting, with a plastic stent, showed a relatively high rate of morbidity and mortality. We report an alternative, unique treatment for unextractable common bile duct stones, using the temporal placement of an expandable metallic stent (EMS) to facilitate passage of fragments through the papilla.

Aged↗
PubMed2000

Autoantibodies against the specific epitope of human tropomyosin(s) detected by a peptide based enzyme immunoassay in sera of patients with ulcerative colitis show antibody dependent cell mediated cytotoxicity against HLA-DPw9 transfected L cells.

BACKGROUND AND AIMS: Recent studies suggest that tropomyosin (TM) may act as a putative autoantigen in ulcerative colitis (UC). Recently, we identified, by computer homology analysis, a specific peptide (HIAEDADRK) in human TM that can bind to HLA-DPw9. The aim of this study was to investigate the presence of autoantibodies against this peptide in UC. METHODS: Antibodies were measured by ELISA with a synthetic peptide in 20 healthy volunteers, 48 patients with UC, 26 with Crohn's disease (CD), eight with primary sclerosing cholangitis (PSC), and six with primary biliary cirrhosis (PBC). The functional significance of antibodies was investigated by antibody dependent cell mediated cytotoxicity (ADCC) against DPw9 transfected L cells using a standard (51)Cr release assay. RESULTS: Optical density values (mean (SD)) of sera from patients with UC (1.40 (0. 52)) and PSC (1.65 (0.12)) were significantly higher than those from healthy volunteers (0.32 (0.28)) (p<0.05), CD (0.50 (0.34)) (p<0.05) and PBC (0.14 (0.09)) (p<0.05). Values in UC decreased with clinical improvement. The ADCC activity of UC sera correlated well with antibody titre against this synthetic peptide. CONCLUSIONS: Anti-TM antibody was detected in UC sera by a specific peptide based ELISA with high reproducibility. This peptide may be an antigenic epitope of TM involved in the immunopathogenesis of UC and, perhaps, PSC.

Adolescent↗
PubMed2000

Balloon-occluded endoscopic retrograde ileography.

For diagnostic ileography, the authors developed balloon-occluded endoscopic retrograde ileography and performed 77 studies in 36 consecutive patients with Crohn disease. Balloon-occluded endoscopic retrograde ileography proved to be useful in visualization of minute mucosal lesions such as aphthous ulcers and lymphoid hyperplasia in the distal ileum, and satisfactory ileographic images of Crohn disease were obtained in 54 (70%) studies.

Adolescent↗
PubMed2000

Cocaine-amphetamine-regulated transcript (CART) acts in the central nervous system to inhibit gastric acid secretion via brain corticotropin-releasing factor system.

Recent study has indicated that cocaine-amphetamine-regulated transcript (CART) is an anorectic chemical in the brain. In the present study, we examined the hypothesis that CART may act in the central nervous system to alter gastric function. Food consumption, gastric acid secretion, and gastric emptying were measured after injection of CART into the cerebrospinal fluid in 24-h fasted Sprague Dawley rats. Central injection of CART inhibited food intake, gastric acid secretion, and gastric emptying. In contrast, ip injection of CART failed to inhibit gastric acid secretion and gastric emptying, suggesting that CART acts in the brain to suppress gastric acid secretion and gastric emptying. In the vagotomized animals, centrally administered CART did inhibit pentagastrin-stimulated gastric acid secretion. The CART-induced acid inhibition was also observed in rats treated with indomethacin, a cyclooxygenase inhibitor. In contrast, pretreatment with central administration of a CRF receptor antagonist, alpha-helical CRF9-41, completely blocked the central CART-induced inhibition of gastric acid secretion. All these results suggest that CART acts in the brain to inhibit gastric function via brain CRF system. The vagal pathway and the prostaglandin system are not involved in the acid inhibition.

Animals↗
PubMed1999

Activation of PPARgamma inhibits cell growth and induces apoptosis in human gastric cancer cells.

We investigated the expression of peroxisome proliferator-activated receptor gamma (PPARgamma) and the role of PPARgamma in cell growth in human gastric cancer cells. Reverse transcription-polymerase chain reaction, Northern blot and Western blot analyses showed that a human gastric cancer cell line, MKN45, expressed PPARgamma mRNA and protein. Luciferase assay in MKN45 cells showed that troglitazone, a selective ligand for PPARgamma, transactivated the transcription of a peroxisome proliferator response element-driven promoter. Troglitazone or pioglitazone, selective ligands for PPARgamma, inhibited the growth of MKN45 cells in a dose-dependent manner. Co-incubation of MKN45 cells with troglitazone induced DNA ladder formation. These results suggest that human gastric cancer cells express PPARgamma and that activation of PPARgamma inhibits cell growth and induces apoptosis in gastric cancer cells.

Acyl-CoA Oxidase↗
PubMed1999

Stimulation of gastric acid secretion by centrally administered orexin-A in conscious rats.

Orexins are novel neuropeptides that are localized in neurons within the lateral hypothalamus and regulate feeding behavior. The lateral hypothalamus also plays an important role in the central regulation of gut function. We therefore hypothesized that orexins might be involved in the central control of gastric acid secretion. To address this question, we examined the effect of central injection of orexins on gastric acid secretion in rats. Intracisternal injection of synthetic orexin-A but not orexin-B dose-dependently stimulated acid secretion while intraperitoneal administration of orexin-A failed to stimulate acid secretion. Vagotomy or atropine abolished the action by central orexin-A. These data suggest for the first time that orexin-A may act in the brain to stimulate gastric acid secretion by modulating the vagal system. Considering its stimulatory action on feeding, we hypothesize here that orexin-A is a candidate mediator of cephalic phase gastric secretion.

Animals↗
PubMed1999

Localization of syndecan-1 in human gastric mucosa associated with ulceration.

Syndecans, cell surface heparan sulphate proteoglycans, are known to function as cell adhesion molecules and as a co-receptor for heparin-binding growth factors that have important roles in tissue homeostasis and repair, but the localization of syndecans in gastric mucosa and their role in gastric ulcer healing are not known. The licalization of syndecan-1, a subfamily protein of syndecans expressed on epithelial cells, was studied in 12 surgically resected human stomachs containing an ulcer or early scar tissue. Localization of syndecan-1 was detected both by immunohistochemistry and by in situ hybridization In non-ulcer sites of gastric mucosa, syndecan-1 protein was expressed at the basolateral surface of foveolar epithelial cells and the cells of intestinal metaplasia, and at the cell surface of stromal plasma cells. In addition, positive dots of syndecan-1 were found in the cytoplasmic area of parietal cells. Foveolar epithelial cells at active stage ulcer margins showed nearly the same intensity of staining as those at non-ulcer site mucosa. By contrast, enhanced staining was obtained in elongated regenerative foveolar cells at the healing ulcer margins and the early scar tissues. The migrating cells on ulcer floors also expressed syndecan-1 protein. The expression sites of syndecan-1 mRNA mostly coincided with those of syndecan-1 protein. These results suggest that syndecan-1 participates in cell adhesion mainly at the foveolar epithelium and plays a role in the healing of gastric ulcers by interacting with heparin-binding growth factors.

Gastric Mucosa↗
PubMed1999

Epithelial cell proliferation and gene mutation in the mucosa of gallbladder with pancreaticobiliary malunion and cancer.

The significant association between pancreaticobiliary malunion (PBM), especially undilated-type PBM, and a high risk of gallbladder cancer is known. Reflux and stasis of pancreatic juice induce various epithelial changes in the gallbladder. Recently, epithelial hyperplasia of the gallbladder was shown to be significantly and frequently associated with undilated-type PBM, and it is suggested that the majority of epithelial hyperplasia may exist at birth or be acquired in early childhood, and thereafter present throughout the lives of PBM patients. Cell kinetic studies demonstrated a significant stepwise increase in cellular proliferative activity from normal gallbladder mucosa, through epithelial hyperplasia to cancer. Epithelial hyperplasia with increased proliferative activity may predispose the mucosa to mutational events, thereby increasing cancer risk in PBM patients. K-ras mutations were frequently detected in gallbladder cancer in PBM patients and in epithelial hyperplasia as well. Epithelial hyperplasia is demonstrated to be an important premalignant lesion of gallbladder cancer. A multistep process of carcinogenesis as a consequence of multiple genetic alterations of oncogenes and tumor suppressor genes has been demonstrated in various organs; however, there is limited information on the molecular mechanism in gallbladder carcinogenesis with PBM. Recent findings support the idea that epithelial hyperplasia plays an important role in gallbladder carcinogenesis with PBM and also support the concept that neoplastic development in gallbladder with PBM also evolves through a multistep process associated with hyperproliferation and genetic alterations.

Adenocarcinoma↗
PubMed1999

An inverse correlation between serum leptin levels and hemoglobin A1c in patients with non-insulin dependent diabetes mellitus.

We measured serum leptin concentrations in 70 patients with diabetes mellitus to investigate the relationship between serum leptin levels and glycemic control. A positive correlation between serum leptin levels and body mass index or plasma insulin was obtained as reported previously. The present study also demonstrated an inverse association of serum leptin levels with hemoglobin A1c (HbA1c). Multiple regression analysis revealed that HbA1c was an independent determinant of serum leptin levels. These results suggest that HbA1c may be a factor to influence serum leptin levels and that hyperglycemia for a long period or poorly controlled diabetes may reduce leptin levels.

Adult↗