Biomedical subjects
Publications and source records attributed to Ken Sato.
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BACKGROUND/AIMS: Hepatitis C virus (HCV) infection is a significant global public health problem. In clinical studies, zinc has been closely related to the pathogenesis of chronic hepatitis C. However, the role of zinc in both viral replication and the expression of viral proteins remains unclear. We aimed to clarify the effect of zinc on the replication of HCV in vitro. METHODS: We incubated subgenomic HCV replicon cells (sO) and genome-length HCV RNA-replicating cells (O) treated with several chemicals including trace elements. Total RNAs were collected and subjected to real-time reverse-transcriptase polymerase chain reaction in order to examine the level of HCV RNA replication, and Western blotting was performed to confirm the expression of viral proteins. RESULTS: Iron salts and interferon-alpha suppressed HCV RNA replication and protein expression in both sO and O cells. Zinc salts effectively reduced the viral replication in the genome-length HCV RNA replication system but not in the subgenomic HCV replicon system. CONCLUSIONS: We demonstrated that zinc may play an important role as a negative regulator of HCV replication in genome-length HCV RNA-replicating cells. Zinc supplementation thus appears to offer a novel approach to the development of future strategies for the treatment of intractable chronic hepatitis C.
Oral metastases from hepatocellular carcinoma are very rare. We encountered a case of hepatocellular carcinoma with a solitary metastasis to the mandible as an initial manifestation. The patient was a 76-year-old man who was admitted for left mandibular swelling. A biopsy specimen of mandible was suspected to be a metastatic tumor. The histological findings, abdominal computed tomography, bone scintigraphy, and F-18 fluorodeoxyglucose-positron emission tomography (FDG-PET) revealed it to be a solitary metastasis from hepatocellular carcinoma. As a result, he was diagnosed to have liver cirrhosis due to a hepatitis C virus infection and hepatocellular carcinoma with a solitary metastasis to the mandible. The primary lesion was treated with transcatheter arterial embolization (TAE), and the metastasis to the mandible was surgically resected. The patient survived for 9 months after treatment without recurrence.
The term ectopic varices is used to describe dilated portosystemic collateral veins in unusual locations other than the gastroesophageal region. We recently experienced a rare case of ectopic varices that developed in the right diaphragm and ruptured into the pleural cavity. A 68-year-old female with hepatocellular carcinoma complicated with liver cirrhosis was admitted due to an acute onset of dyspnea and right bloody pleural effusion. Because of the patient's advanced hepatocellular carcinoma and poor condition, conservative therapies such as hemostats and blood transfusion were selected. Even though the bleeding to the pleural cavity stopped spontaneously, the patient died due to a progression of liver failure. Autopsy revealed a huge collateral vein in the right diaphragm. The etiology, prevalence, relationship with portal hypertension, and treatment of ectopic varices are discussed herein.
5-FU is the drug most frequently used to treat biliary tract cancer, while dihydropyrimidine dehydrogenase (DPD) is known to be a principal factor in 5-FU drug resistance. However, whether DPD activity and mRNA levels correlate with response to 5-FU is unknown for biliary tract cancers. The precise mechanism of DPD regulation also remains to be elucidated. In the present study, we quantitatively analyzed DPD mRNA in 8 biliary tract cancer cell lines using real-time RT-PCR, and assessed whether DPD mRNA levels correlate with DPD activity or the sensitivity to 5-FU. Finally, we examined the epigenetic gene silencing of DPD using one of the 8 lines, a gallbladder cancer cell line with deficient DPD expression, KMG-C. Strong correlation was found between DPD activity and DPD mRNA expression in the 8 cancer cell lines (R=0.797, P=0.0148). DPD mRNA expression and DPD activity exhibited positive correlation with the IC50 for 5-FU (R=0.658, R=0.644, respectively), although these relationships were not statistically significant. In the KMGC cells with deficient DPD mRNA levels, restoration of DPD expression was observed by 5-Aza-2' deoxycytidine (5-aza-C) treatment in a dose-dependent manner, suggesting gene suppression by promoter hypermethylation. Combined bisulfite restriction analysis was performed to analyze the methylation on CpG islands around the 5'-flanking region and intron 1 of the DPD gene, however, no methylated CpG sites were identified in these regions. In addition, the restored DPD expression level was more strongly induced by the histone deacetylase (HDAC) inhibitor, trichostatin A (TSA), than 5-aza-C treatment. These findings suggest that other mechanisms, including histone modification, may be important for DPD suppression. In conclusion, these results may aid the selection of 5-FU chemotherapy following determination of DPD expression in biliary tract cancers. Furthermore, epigenetic gene silencing appears to be an important mechanism of DPD suppression in biliary tract cancer.
Irritable bowel syndrome (IBS) is a very common gastrointestinal disorder. The prevalence of IBS is about 10-15% of the general population. Epidemiological studies suggested that the prevalence of IBS decreased with age, but IBS remains an important gastrointestinal illness in the aged. But there has been very few research examining on IBS in elderly. Whether advancing age impacts on IBS is largely unknown and how the disorder manifest in the elderly remains unclear. Aging is connected with an increasing prevalence of many chronic neurological difficulties, cardiovascular diseases and mental disabilities. The management of the IBS needs to take the age-related issues into account in elderly. Clinical therapeutic trials should be undertaken in elderly people to ascertain treatment.
AIM: To investigate the in vivo effects of NK2 on liver regeneration after partial hepatectomy (PH). METHODS: Survival after PH was observed with 21 NK2 transgenic mice and 23 wild-type (WT) mice over 10 d. Liver regeneration was analyzed using histology and immunohistochemistry. Expressions of genes were analyzed using Northern blot analysis, immunoprecipitation and immunoblotting, and reverse transcriptase polymerase chain reaction assay. Kaplan-Meier method and the log-rank test were used for analyzing the survival after PH. Differences in the results of immunohistochemistry and percentage of liver regeneration was determined by the Student's t-test. RESULTS: More than half of NK2 transgenic mice died within 48 h after PH. After PH, increased deposition of small lipid droplets in hepatocytes was evident and hepatic proliferation was inhibited in NK2 transgenic mice. The hepatic expression and kinase activity of HGF receptor, c-Met, were unchanged among WT mice and NK2 transgenic mice after PH. The expression of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in liver tissues were prolonged in NK2 transgenic mice that died after PH. CONCLUSION: Our findings indicate that over-expression of NK2 inhibits liver regeneration after PH.
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Adult onset type II citrullinemia (CTLN2) is an autosomal recessive disease accompanied with hyperammonemia and a sudden onset of psychiatric disorders. We demonstrated three male patients with CTLN2 having a liver histology of non-alcoholic steatohepatitis (NASH). Patients with NASH were analyzed for the causative gene of CTLN2, SLC25A13 and discussed.
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Acute esophageal necrosis (AEN) is extremely rare and the pathogenesis of this is still unknown. We report a case of AEN caused by alcohol abuse. In our case, the main pathogenesis could be accounted for low systemic perfusion caused by severe alcoholic lactic acidosis. After the healing of AEN, balloon dilatation was effective to manage the stricture.
It has been reported that malignancies of natural killer (NK) cell precursors, which are present in both myeloid and lymphoid antigens, are characterized by immature lymphoblastoid morphology with CD7+, CD33+ and CD56+ phenotype. Here, we report a 18-year-old man who was diagnosed with CD33- and CD13- NK cell precursor acute leukemia at first diagnosis. Following a 3-year remission state, he had a relapse as a testicular tumor and CD33+ myeloid/NK cell precursor acute leukemia after allogenic BMT. This case suggests that myeloid antigens are not necessary for diagnosis of myeloid/NK cell precursor acute leukemia.
Prolactin, a peptide hormone essential for the development and function of reproductive organs, is involved in development of breast, prostate and colorectal cancers. However, the role of prolactin on the carcinogenesis of ovarian carcinomas is unclear. In this study, we show that mRNA of prolactin receptor is expressed in 5 out of 9 ovarian carcinoma cell lines, 15 out of 17 cases of surgical samples and all of normal ovarian surface epithelium, while prolactin transcript is detected only in 1 ovarian carcinoma cell line and in 1 of the surgical samples. For the prolactin receptor-positive ovarian carcinoma cells, exogenous prolactin did not affect the proliferation but markedly inhibited apoptosis. Therefore, actual cell growth was enhanced by prolactin in a dose-dependent manner. The blocking of prolactin receptor by antibody severely impaired the antiapoptotic and growth-promoting effects of prolactin. Interestingly, the cisplatin-induced cell death of the prolactin receptor-positive cells was significantly inhibited by pretreatment with prolactin. These findings indicate a responsiveness of ovarian carcinomas to prolactin and suggest that the prolactin/prolactin receptor system may be a new therapeutic target of ovarian carcinomas.
Here we identify a new regulator of endocytosis called RME-6. RME-6 is evolutionarily conserved among metazoans and contains Ras-GAP (GTPase-activating protein)-like and Vps9 domains. Consistent with the known catalytic function of Vps9 domains in Rab5 GDP/GTP exchange, we found that RME-6 binds specifically to Caenorhabditis elegans RAB-5 in the GDP-bound conformation, and rme-6 mutants have phenotypes that indicate low RAB-5 activity. However, unlike other Rab5-associated proteins, a rescuing green fluorescent protein (GFP)-RME-6 fusion protein primarily localizes to clathrin-coated pits, physically interacts with alpha-adaptin, a clathrin adaptor protein, and requires clathrin to achieve its cortical localization. In rme-6 mutants, transport from the plasma membrane to endosomes is defective, and small 110-nm endocytic vesicles accumulate just below the plasma membrane. These results suggest a mechanism for the activation of Rab5 in clathrin-coated pits or clathrin-coated vesicles that is essential for the delivery of endocytic cargo to early endosomes.
BACKGROUND: We previously demonstrated in an immunohistochemical study that reduced expression of O(6)-methylguanine-DNA methyltransferase (MGMT) correlated with a poorer prognosis in patients with biliary tract cancers. The purpose of this study was to clarify how MGMT deficiency leads to a poor outcome in biliary tract cancer. Thus, we examined epigenetic (promoter methylation) and genetic (gene mutation) alterations in biliary tract cancer. METHODS: We examined 37 biliary tract cancer specimens from patients who underwent surgical resection. Promoter methylation was determined by one-step or two-step methylation-specific polymerase chain reaction. Gene mutation was identified by direct sequencing. The expression of MGMT protein in paraffin-embedded tissue was examined by immunohistochemistry. RESULTS: Frequencies of promoter methylation were 70% for p16/INK4a, 49% for MGMT, 46% for hMLH1, 41% for E-cadherin, and 32% for DAPK genes. MGMT methylation status was closely correlated with the MGMT protein expression determined by immunohistochemistry (P < .001). Although this was not statistically significant, biliary tract cancer tumors with MGMT methylation expressed multigene methylation more frequently than tumors without MGMT methylation (P = .071). A total of 33 mutations were identified in 4 cancer-related genes: p53, K-ras, beta-catenin, and p16/INK4a genes. The most common mutation was GC to AT transitions (58%), which were significantly associated with MGMT promoter methylation (P = .011). These findings suggest that loss of MGMT expression by promoter methylation results in accumulation of GC to AT gene mutations. CONCLUSIONS: Reduced MGMT expression may increase the malignant potential of biliary tract cancer through both epigenetic and genetic mechanisms.
COPII coat proteins are required for direct capture of cargo and SNARE proteins into transport vesicles from the endoplasmic reticulum (ER). Cargo and SNARE capture occurs during the formation of a 'prebudding complex' comprising a cargo, Sar1p-GTP and the COPII subunits Sec23/24p. The assembly and disassembly cycle of the prebudding complex on ER membranes is coupled to the Sar1p GTPase cycle. Using FRET to monitor a single round of Sec23/24p binding and dissociation from SNAREs in reconstituted liposomes, we show that Sec23/24p dissociates from v-SNARE and complexed t-SNARE with kinetics slower than Sar1p-GTP hydrolysis. Once Sec23/24p becomes associated with v-SNARE or complexed t-SNARE, the complex remains assembled during multiple rounds of Sar1p-GTP hydrolysis mediated by the GDP-GTP exchange factor Sec12p. These data suggest a model for the maintenance of kinetically stable prebudding complexes during the Sar1p GTPase cycle that regulates cargo sorting into transport vesicles.
Pancreatic or gastric metastases from other primary malignancies are rare, especially from leiomyosarcoma. We report a case of leiomyosarcoma in the left lower leg with metastases to the pancreas and stomach. A 61-year-old man had liver cirrhosis caused by hepatitis C virus infection and was followed up by his primary physician. Two years before presentation at our hospital, he had undergone surgical resection of leiomyosarcoma in the left lower leg and systemic chemotherapy for multiple metastatic tumors in the lung. On admission, endoscopic examination and computed tomography were performed for a routine checkup to exclude esophageal varices and liver tumor. Although the patient had no specific symptoms, multiple gastric and pancreatic metastases were identified by endoscopy and computed tomography, respectively. In general, metastases to the pancreas and stomach are rare. We discuss the clinical and diagnostic findings of pancreatic and gastric metastases by reviewing previously reported cases.
Natural killer T (NKT) cells share features of both classical T cells and NK cells. NKT are heterogenous populations, and recognize glycolipids associated with CD1d molecule. We investigated Th1/Th2 cytokine production as well as frequency and phenotype of circulating NKT cells in 14 healthy subjects and in patients during therapy with type C chronic hepatitis (CH; 14 cases) and hepatocellular carcinoma (HCC; 13 cases). Peripheral blood mononuclear cells (PBMC) were obtained before and 2 weeks later interferon (IFN)/ribavirin and radiofrequency ablation therapy for CH and HCC, respectively. PBMC were cultured for 10 days with alpha-galactosylceramide (alpha-GalCer) and interleukin-2 (IL-2). Frequencies and IFN-gamma/IL-4 production of NKT cells were analyzed using flow cytometry. Intrahepatic lymphocytes were analyzed in seven CH patients with liver biopsy specimen. Prevalence of circulating Valpha24+CD3+ T cells was 0.9+/-0.9% of PBMC for controls and increased to 8.5+/-8.9% (p<0.001) in response to alpha-GalCel. Similar frequency and expansion were noted in CH. The frequency increased during therapy. The prevalence in HCC tended to be high compared to controls and response to alpha-GalCel was well. Although frequency of Valpha24+Vbeta11+CD3+ T cells was low in all groups, the distribution pattern was similar to Valpha24+Vbeta11-CD3+ T cells. Prevalence of CD56+CD3+ T cells was low independent of therapy in CH (2-3%) compared to 5.0+/-4.0% of controls, although response to alpha-GalCel was not impaired. IFN-gamma production of Valpha24+CD3+ T cells did not differ among groups, but became greater after treatment in contrast to lowered IL-4 production. Frequencies of NKT populations were higher in liver than in peripheral blood. Our study suggests that CD1d-reactive T cells have distinct distribution in different populations and therapy for patients alters cytokine response of NKT cells.