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Tatsuya Yamashita

Publications and source records attributed to Tatsuya Yamashita.

16 recordsLinked to original sources
PubMed2025

The SELENOP Polymorphism rs7579 Predicts Hepatic Steatosis in Females With Insulin Resistance in the General Population.

CONTEXT: Selenoprotein P is a hepatokine associated with several metabolic processes. Rs7579 (C > T) is a SeP-related functional single nucleotide polymorphism. OBJECTIVE: In this study, we aimed to identify the environmental factors affecting the relationship between rs7579 and metabolic diseases, such as metabolic dysfunction-associated steatotic liver disease, in the general population. METHODS: This cross-sectional study was based on the Shika Study, a survey of residents in the Noto Peninsula of Ishikawa Prefecture. We analyzed a total of 900 adults, measuring full-length selenoprotein P (FL-SeP) serum levels using a sol-particle homogeneous immunoassay. RESULTS: We observed that selenium and FL-SeP serum levels were associated with dyslipidemia. In males, serum selenium was associated with dyslipidemia and hepatic steatosis. However, in females, FL-SeP tended to be associated with diabetes. Participants carrying the TT genotype and hepatic steatosis exhibited higher levels of liver enzymes, insulin, the homeostatic model assessment of insulin resistance (HOMA-IR), and the homeostasis model assessment of β-cell function than those without hepatic steatosis or with other genotypes. In females carrying the TT genotype of rs7579, hepatic steatosis, hypertension, diabetes, obesity, and metabolic syndrome were associated with higher HOMA-IR levels. CONCLUSION: In this study, we revealed that the association between metabolic diseases and HOMA-IR differed single nucleotide polymorphism genotype and sex dependently. In females carrying the TT genotype of rs7579, hepatic steatosis-associated metabolic disorders (diabetes, hypertension, obesity, and metabolic syndrome) were associated with higher HOMA-IR. The results of this study open the way to genetic signatures-based personalized preventive medicines.

CCDC152↗
PubMed2006

Virological effects and safety of combined double filtration plasmapheresis (DFPP) and interferon therapy in patients with chronic hepatitis C: A preliminary study.

PURPOSE: In patients with chronic genotype 1b hepatitis C and a high viral load, the viral load was reduced by double filtration plasmapheresis (DFPP), followed by combined interferon and ribavirin therapy. The safety and virological effects of this treatment method were preliminarily investigated. METHODS: In nine patients with chronic hepatitis C, DFPP was performed three times on days 1, 2, and 4, and the administration of interferon and ribavirin was initiated immediately after DFPP on day 1. RESULT: The HCV RNA was undetectable in all patients after the plasma was passed through a plasma fractionator (second filter) in the DFPP circuit. After 2 weeks, the HCV RNA tended to decrease in the DFPP group more than in the control group (-2.45+/-1.12 versus -1.57+/-0.95, P=0.073). However, this decrease was not attributable to a sustained virological response (SVR) (22.2% versus 18.2%, P=0.822). Most of the adverse events were caused by the interferon and ribavirin combination therapy. CONCLUSION: DFPP can be safely performed concomitantly with interferon and ribavirin combination therapy in chronic hepatitis C patients. The combination may contribute to an early virological response. The effect of DFPP on the SVR and its significance remain to be clarified.

Journal Article↗
PubMed2006

Identification of alpha-fetoprotein-derived peptides recognized by cytotoxic T lymphocytes in HLA-A24+ patients with hepatocellular carcinoma.

Alpha-fetoprotein (AFP) has been proposed as a potential target forT-cell-based immunotherapy for hepatocellular carcinoma (HCC), but the number of its epitopes that have been identified is limited and the status of AFP-specific immunological responses in HCC patients has not been well-characterized. To address the issue, we examined the possibility of inducing AFP-specific cytotoxic T cells (CTLs) using novel HLA-A*2402-restricted T-cell epitopes (HLA, human leukocyte antigen) derived from AFP and then analyzed the relationship between its frequency of occurrence and clinical features associated with patients having HCC. Five AFP-derived peptides containing HLA-A*2402 binding motifs and showing high binding affinity to HLA-A*2402 induced CTLs to produce IFN-gamma and kill an AFP-producing hepatoma cell line. The frequency of AFP-specific CTLs was 30-190 per 1 x 10(6) peripheral blood mononuclear cells, which was the same as that of other immunogenic cancer associated antigen-derived epitopes. Analyses of the relationships between AFP-specific CTL responses and clinical features of patients with HCC revealed that AFP epitopes were more frequently recognized by CTLs in patients with advanced HCC correlating to tumor factors or the stage of TNM classification. The analyses of CTL responses before and after HCC treatments showed that the treatments changed the frequency of AFP-specific CTLs. In conclusion, we identified five HLA-A*2402-restricted T-cell epitopes derived from AFP. The newly identified AFP epitopes could be a valuable component of HCC immunotherapy and for analyzing host immune responses to HCC.

Aged↗
PubMed2006

Cytotoxic T cell responses to human telomerase reverse transcriptase in patients with hepatocellular carcinoma.

Human telomerase reverse transcriptase, hTERT, has been identified as the catalytic enzyme required for telomere elongation. hTERT is expressed in most tumor cells but seldom expressed in most human adult cells. It has been reported that 80% to 90% of hepatocellular carcinomas (HCCs) express hTERT, making the enzyme a potential target in immunotherapy for HCC. In the current study, we identified hTERT-derived, HLA-A*2402-restricted cytotoxic T cell (CTL) epitopes and analyzed hTERT-specific CTL responses in patients with HCC. Peptides containing the epitopes showed high affinity to bind HLA-A*2402 in a major histocompatibility complex binding assay and were able to induce hTERT-specific CTLs in both hTERT cDNA-immunized HLA-A*2402/Kb transgenic mice and patients with HCC. The CTLs were able to kill hepatoma cell lines depending on hTERT expression levels in an HLA-A*2402-restricted manner and induced irrespective of hepatitis viral infection. The number of single hTERT epitope-specific T cells detected by ELISPOT assay was 10 to 100 specific cells per 3 x 10(5) PBMCs, and positive T cell responses were observed in 6.9% to 12.5% of HCC patients. hTERT-specific T cell responses were observed even in the patients with early stages of HCC. The frequency of hTERT/tetramer+ CD8+ T cells in the tumor tissue of patients with HCC was quite high, and they were functional. In conclusion, these results suggest that hTERT is an attractive target for T-cell-based immunotherapy for HCC, and the identified hTERT epitopes may be valuable both for immunotherapy and for analyzing host immune responses to HCC.

Animals↗
PubMed2006

The development and clinical features of splenic aneurysm associated with liver cirrhosis.

OBJECTIVES: Splenic artery aneurysm (SAA) is usually asymptomatic, but can be fatal if it ruptures. Portal hypertensive patients with varix or splenomegaly are sometimes complicated by SAA. However, there have been no large-scale clinical studies regarding whether liver cirrhosis itself is associated with splenic aneurysm regardless of varix or splenomegaly. METHODS: In the present study, we retrospectively analyzed 303 cirrhotic patients examined with arteriography. The diagnosis and characteristics of SAAs were determined, and the relation with splenic artery diameter was evaluated. RESULTS: Nine patients (2.97%) had 12 complicated SAAs. The aneurysms, which measured 4-22 mm in diameter, were all saccular, and occurred commonly in the splenic hilum (50.0%). A correlation was noted between splenic artery diameter and aneurysm diameter (R(2)=0.706). Aneurysm growth was strongly associated with an increase in diameter of the splenic artery trunk (R(2)=0.705), which is closely related to arterial flow. CONCLUSIONS: SAA is considered a complication of cirrhosis. The increase in splenic artery diameter may result in SAA enlargement and rupture. Elective procedures should be considered based on the follow-up of main trunk or diameter of the splenic artery in addition to SAA size, a known risk factor of aneurysmal rupture.

Adult↗
PubMed2006

[A case of recurrent pancreatic cancer responding to TS-1 combined gemcitabine chemotherapy after UFT combined gemcitabine chemotherapy resulting progressive disease].

The patient diagnosed as recurrent pancreatic cancer was treated with UFT combined gemcitabine (GEM) chemotherapy. After one cycle of therapy, the anti-tumor effect was progressive disease with obstructive jaundice and enlargement of lymph node metastasis and liver metastasis. The chemotherapy was changed to TS-1 combined GEM chemotherapy and resulted in partial response. Only grade 3 leukopenia was observed as an adverse effect. Some cases may be effectively treated by TS-1 combined chemotherapy after treatment failure of UFT combined GEM chemotherapy. This therapy is simple and possible to continue safely on an ambulatory basis while maintaining quality of life.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

Berry splenic artery aneurysm rupture in association with segmental arterial mediolysis and portal hypertension.

A rare case of berry splenic artery aneurysm (SAA) rupture associated with segmental arterial mediolysis (SAM) and portal hypertension is reported. A 66-year-old woman, diagnosed as having liver cirrhosis and portal hypertension 6 years earlier, suddenly developed a lancinating pain in the upper abdomen and lost consciousness. She recovered consciousness while being transferred to hospital by ambulance. During the investigations, her level of consciousness suddenly deteriorated. Ultrasonography showed a massive intraperitoneal hemorrhage, and she died 5(1/2) h after admission. On gross examination at autopsy it was not possible to find the rupture point of the vessel because the pancreas was embedded in a massive hematoma. However, careful dissection of the pancreatic tail after fixation revealed a berry aneurysm measuring 0.8 cm in diameter in a branch adjacent to the bifurcation in the distal third of the main splenic artery. Microscopic examination detected a rupture of the aneurysm. The histology of the arterial wall proximal to the aneurysm showed typical SAM. In general, berry SAA caused by SAM is rare and unlikely to rupture. The SAA in the present case likely occurred and ruptured due to the combination of SAM and portal hypertension.

Aged↗
PubMed2004

An open-label study of administration of EH0202, a health-food additive, to patients with chronic hepatitis C.

BACKGROUND: In this study, we examined the effect of EH0202, a mixture of four herbal extracts that are known to induce interferons, on hepatitis C virus (HCV)-RNA levels in patients with chronic hepatitis C. METHODS: This was an open-label uncontrolled study. The study subjects ingested food containing EH0202 daily for 3 months, which was equivalent to 1 g of desiccated herbs daily. Clinical symptoms, hematology and biochemical examinations, urine, and HCV-RNA levels were examined before, during (1 month), and after the EH0202 treatment (3 months). RESULTS: Among the 35 patients who successfully completed the study, there were improvements in malaise (seen in 6 patients before and in 2 after EH0202 treatment), bloating sensation in the abdomen (seen in 2 before and in none after treatment), and nausea and vomiting (seen in 2 before and in 1 after treatment). There were no changes in hematology or biochemical examination parameters. There was a statistically significant decrease in HCV-RNA levels in patients with high viral titers after 3 months of EH0202 administration. No serious adverse events were observed with the EH0202 treatment. CONCLUSIONS: These findings suggest that EH0202 may be safe and useful in the treatment of patients with chronic hepatitis C. Further studies are, however, needed to obtain a definitive conclusion.

Adult↗
PubMed2003

Enantioselective borodeuteride reduction of aldimines catalyzed by cobalt complexes: preparation of optically active deuterated primary amines.

[reaction: see text] The enantioselective borodeuteride reduction catalyzed by optically active beta-ketoiminato cobalt complexes was applied to N-(di(o-tolyl)phosphinyl)aldimines to afford the corresponding optically active deuterated primary amines in high yields with high enantiomeric excesses after simple deprotection. The present deuteride reduction of aldimines is in the opposite sense of the enantioselective for the previously reported borohydride reduction of ketones or diphenylphosphinyl aldimines. The stereochemical course in these enantioselective reductions is discussed.

Journal Article↗
PubMed2002

Direct interaction between nucleolin and hepatitis C virus NS5B.

Hepatitis C virus (HCV) NS5B is an RNA-dependent RNA polymerase (RdRP), a central catalytic enzyme in HCV replication. While studying the subcellular localization of a NS5B mutant lacking the C-terminal membrane-anchoring domain, NS5Bt, we found that expression of the green fluorescent protein (GFP)-fused form was exclusively nucleolar. Interestingly, the distribution of endogenous nucleolin changed greatly in the cells expressing GFP-NS5B, with nucleolin colocalized with GFP-NS5B in perinuclear regions in addition to the nucleolus, suggesting that NS5B retains the ability to bind nucleolin. The interaction between nucleolin and NS5B was demonstrated by GST pull-down assay. GST pull-down assay results indicated that C-terminal region of nucleolin was important for its binding to NS5B. Scanning clustered alanine substitution mutants library of NS5B revealed two sites on NS5B that binds nucleolin. NS5B amino acids 208-214 and 500-506 were both found to be indispensable for the nucleolin binding. We reported that the latter sequence is essential for oligomerization of NS5B, which is a prerequisite for the RdRP activity. C-terminal nucleolin inhibited the NS5B RdRP activity in a dose-dependent manner. Taken together, this indicates the binding ability of nucleolin may be involved in NS5B functions.

Animals↗
PubMed2002

Hepatitis C virus (HCV) NS5A binds RNA-dependent RNA polymerase (RdRP) NS5B and modulates RNA-dependent RNA polymerase activity.

Hepatitis C virus (HCV) NS5B is RNA-dependent RNA polymerase (RdRP), the essential catalytic enzyme for HCV replication. Recently, NS5A has been reported to be important for the establishment of HCV replication in vitro by the adaptive mutations, although its role in viral replication remains uncertain. Here we report that purified bacterial recombinant NS5A and NS5B directly interact with each other in vitro, detected by glutathione S-transferase (GST) pull-down assay. Furthermore, complex formation of these proteins transiently coexpressed in mammalian cells was detected by coprecipitation. Using terminally and internally truncated NS5A, two discontinuous regions of NS5A (amino acids 105-162 and 277-334) outside of the adaptive mutations were identified to be independently essential for the binding both in vivo and in vitro (Yamashita, T., Kaneko, S., Shirota, Y., Qin, W., Nomura, T., Kobayashi, K., and Mkyrakami, S. (1998) J. Biol. Chem. 273, 15479-15486). We previously examined the effect of His-NS5A on RdRP activity of the soluble recombinant NS5Bt in vitro (see Yamashita et al. above). Wild NS5A weakly stimulated at first (when less than 0.1 molar ratio to NS5B) and then inhibited the NS5Bt RdRP activity in a dose-dependent manner. The internal deletion mutants defective in NS5B binding exhibited no inhibitory effect, indicating that the NS5B binding is necessary for the inhibition. Taken together, our results support the idea that NS5A modulates HCV replication as a component of replication complex.

Animals↗
PubMed2001

Oligomeric interaction of hepatitis C virus NS5B is critical for catalytic activity of RNA-dependent RNA polymerase.

HCV NS5B is an RNA-dependent RNA polymerase (RdRP), a central catalytic enzyme for HCV replication, which has the "palm and fingers" substructure. We recently identified five novel residues critical for RdRP activity (Qin, W., Yamashita, T., Shirota, Y., Lin, Y., Wei, W., and Murakami, S. (2001) Hepatology 33, 728-737). Among them, GLU-18 and His-502, far from the catalytic center, may be involved in conformational change(s) for RdRP activity as addressed in some palm and fingers enzymes. We examined the possibility that NS5B is oligomerized, and we could detect the interaction between two different tagged NS5B proteins in vitro and transiently expressed in mammalian cells. By scanning 27 clustered and then point alanine substitutions in vivo and in vitro, Glu-18 and His-502 were found to be critical for the homomeric interaction in vivo and in vitro, strongly suggesting a close relationship between the oligomerization and RdRP activity of NS5B. All mutants with substitutions at these two residues failed to bind wild type NS5B, however E18H interacted with H502E in vitro and in vivo. Interestingly, the NS5B protein with E18H or H502E did not exhibit RdRP activity, but a mixture of the two mutant proteins did. These results clearly indicate that two residues of HCV NS5B are critical for the oligomerization that is prerequisite to RdRP activity.

Amino Acids↗