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Takeshi Hirayama

Publications and source records attributed to Takeshi Hirayama.

11 recordsLinked to original sources
PubMed2006

Hypercholesterolemia in rats with hepatomas: increased oxysterols accelerate efflux but do not inhibit biosynthesis of cholesterol.

Hypercholesterolemia is an important paraneoplastic syndrome in patients with hepatoma, but the nature of this defect has not yet been identified. We investigated the molecular mechanisms of hypercholesterolemia in a hepatoma-bearing rat model. Buffalo rats were implanted in both flanks with Morris hepatoma 7777 (McA-RH7777) cells. After 4 weeks, tumor weight was 5.5+/-1.7 g, and serum cholesterol level increased from 60+/-2 to 90+/-2 mg/dL. Protein and mRNA expression of the ATP-binding cassette transporters A1 and G1 (ABCA1 and ABCG1) was markedly higher in tumors than in livers. These increases were associated with activation of liver X receptor alpha (LXRalpha) as a result of the increased tissue oxysterol concentrations. The accumulation of oxysterols in the hepatomas appeared to be caused mainly by the upregulation of cholesterol biosynthesis, despite the increased tissue sterol concentrations. Overexpression of the sterol regulatory element-binding protein (SREBP) processing system relative to sterol concentration contributed to the resistance to sterols in this tumor. In addition, bile acid biosynthesis was inhibited despite the reduced expression of the small heterodimer partner (SHP) and activated LXRalpha, which also appeared to contribute to the accumulation of oxysterols followed by the acceleration of cholesterol efflux. In conclusion, hypercholesterolemia in McA-RH7777 hepatoma-bearing rats was caused by increased cholesterol efflux from tumors as a result of activation of LXRalpha. Overexpression of the SREBP processing system contributed to the activation of LXRalpha by maintaining high oxysterol levels in tissue.

ATP Binding Cassette Transporter 1↗
PubMed2005

Apoptosis and inhibition of the phosphatidylinositol 3-kinase/Akt signaling pathway in the anti-proliferative actions of dehydroepiandrosterone.

BACKGROUND: Dehydroepiandrosterone (DHEA) is an endogenous steroid that is synthesized mainly in the adrenal cortex; it is found in plasma as the sulfate-conjugated form (DHEA-S). Pharmacological doses of DHEA exhibit anti-proliferative effects on malignant cell lines and some tumors in experimental animals. The purpose of this study was to evaluate the effect of these steroids on proliferation in human cancer cell lines. METHODS: HepG2 and HT-29 cell lines were treated with DHEA or DHEA-S at 0-200 microM for 24 h or at 100 microM for 8-72 h, and then effects on cell growth, and the cell cycle and on apoptosis, were evaluated by 3-[4,5-dimethylthiazol]-2yl-2,5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry, respectively. Also, the effect of DHEA on phosphatidylinositol 3-kinase (PI3K)/Akt signaling was investigated in HepG2 cells by Western blotting. RESULTS: The growth of HepG2 and HT-29 cells was significantly inhibited by DHEA, in a dose- and time-dependent manner. This inhibition was greater in HepG2 than in HT-29 cells. Accumulation at G0/G1 phase in both cell lines was observed with DHEA treatment. However, apoptosis increased significantly only in HepG2 cells. In contrast, DHEA-S exhibited much weaker growth inhibitory and cytostatic effects on both cell lines, and apoptosis was not detected. In HepG2 cells treated with DHEA, apoptosis was associated with markedly reduced Akt phosphorylation (Thr308 and Ser473), suggesting that DHEA inhibited the PI3K/Akt signaling to induce apoptosis in these cells. CONCLUSIONS: These results suggest that the induction of apoptosis through the inhibition of the PI3K/Akt signaling pathway is one of the anti-proliferative mechanisms of DHEA in certain tumors, but that DHEA also promotes cell-cycle arrest without the induction of apoptosis.

Apoptosis↗
PubMed2005

Frequent occurrence of apoptosis is not associated with pathogenic infectious pancreatic necrosis virus (IPNV) during persistent infection.

Infectious pancreatic necrosis virus (IPNV), a member of the genus Aquabirnavirus and family Birnaviridae, is an unenveloped icosahedral virus with two segments of double-stranded RNA. IPNV causes acute infection in salmonid fry and fingerlings with high mortality. However, this mortality is low as the age increases and survivors become IPNV-carrier fish. In this study, IPNV persistent infection was established in rainbow trout with no clinical signs or mortality. TUNEL staining and immunohistochemistry showed that IPNV antigen-positive cells did not have an apoptotic nucleus in almost all tissue sections and leucocyte smears, indicating that apoptosis was not induced in IPNV antigen-positive cells. The IPNV genome detected by in situ RT-PCR was more frequent than detection of the IPNV antigen by immunohistochemistry in the kidney, spleen, and liver. This result implies that the successive replication would not occur in many IPNV-infected cells. Further, apoptotic cells were predominant in the tissue sections where the signal-positive cells were frequently detected. Therefore, the presence of apoptosis in this study might be associated with host defense mechanisms, which eliminates IPNV-infected cells by the recognition of IPNV genome at the early stage of infection.

Animals↗
PubMed2005

Giant pleomorphic adenoma of the parotid gland with malignant transformation.

A 72-year-old female is described who was admitted to the hospital with a giant mixed tumor of the left parotid gland that had grown to a weight of 6051 g within 20 years and ultimately underwent resection of the mass. Histopathological examination revealed adenocarcinoma cells with hyperchromatic nuclei and mitotic figures proliferated in pleomorphic adenoma. Many authors have reported giant tumors weighing more than a few kilograms of the parotid glands, and most were benign. The present tumor was the sixth largest among all the parotid tumors, including both benign and malignant, which were reported. Furthermore, our case was the largest one confirmed as malignant recorded in the world literature. The tumor was successfully resected with no marked facial nerve paralysis.

Adenoma, Pleomorphic↗
PubMed2005

Quantification of aquabirnaviruses isolated from different host species by real-time RT-PCR.

Real-time reverse transcription (RT)-PCR was developed to detect and quantify successfully aquatic birnaviruses (ABVs) from fish tissue and seawater samples. This method detected marine birnavirus (MABV) RNA in several samples, and the detection was specific for ABVs. Monitoring the MABV strain Y-6 RNA quantification by real-time RT-PCR showed replication kinetics of MABV after experimental infection in vitro. We found the quantity of ABVs isolated from different host species by using combined virus absorption in cell culture and real-time RT-PCR. Although all specimens showed no symptoms of viral infection, ABVs were detected regardless of host species. In conclusion, real-time RT-PCR was shown to be a sensitive and reliable tool to detect and quantify ABVs in cultured fish. This method is useful procedure to show details of horizontal or vertical infections by ABVs in the breeding water of aquatic animals.

Animals↗
PubMed2005

[Interaction mechanism of marine birnavirus (MABV) in fish cell lines].

Marine birnavirus (MABV) is a member of the genus Aquabirnavirus of the family Birnaviridae. MABV is an unenveloped icosahedral virus about 60 nm in diameter with two genomes of double-stranded RNA. MABV adsorbed not only onto the cell surfaces of susceptible (CHSE-214 and RSBK-2) cells but also onto resistant (FHM and EPC) cells. Furthermore, the virus entered into the cytoplasm through the endocytotic pathway in CHSE-214, RSBK-2 and FHM cells but did not penetrate EPC cells. The virus was found to bind to an around 250 kDa protein on CHSE-214, RSBK-2, FHM and EPC cells. The syntheses of viral proteins pVP2, NS and VP3 and further proteolytic processing after viral infection were examined by using Western blot analysis. pVP2, NS and VP3 were detected in the cytosolic fractions of CHSE-214, RSBK-2 and FHM cells at 4 h after infection. At this time, VP3 underwent further proteolytic processing in the cytosolic fractions of CHSE-214 and RSBK-2 cells. The expression of pVP2, NS and VP3 increased and pVP2 and NS also underwent further proteolytic processing similar to VP3 in the cytosolic fractions of CHSE-214, RSBK-2 and FHM cells at 8 h after infection. The further proteolytic processing of VP3 was detected in the nuclear fractions of CHSE-214, RSBK-2, but VP3 was detected as a single band in the nuclear fraction of FHM cells. pVP2 and NS were detected as thin bands only in the nuclear fractions of CHSE-214 cells. The results of Western blot analysis demonstrated that pVP2, NS and VP3 are localized in the nuclear fraction when they were independently expressed in CHSE-214, RSBK-2, FHM and EPC cells. The expression pattern in the cytosolic fraction was identical among the four cell lines when pVP2 and NS were independently expressed. However, pVP2 and NS were not detected in the nuclear fraction of CHSE-214 cells. Further proteolytic processing of VP3 was detected in both cytosolic and nuclear fractions of RSBK-2 ,FHM and EPC cells (Low level in EPC cell), but not in CHSE-214 cells when VP3 was independently expressed. Then, the processes of preVP2 to form morphological assemblages in the presence of VP3 or the cleavage of VP3 into two proteins in CHSE-214 cells were studied. When preVP2- and VP3 were co-expressed, virion like particles (64 nm, diameter) were observed close to the nuclear membrane by electron microscopy. The co-expression of preVP2 and the cleaved VP3 proteins led to an efficient assembly of tubules (22 nm, diameter). Further important finds will be obtained by this infection system using 4 fish cell lines in the next couple of years.

Animals↗
PubMed2004

Disrupted coordinate regulation of farnesoid X receptor target genes in a patient with cerebrotendinous xanthomatosis.

Cerebrotendinous xanthomatosis (CTX), sterol 27-hydroxylase (CYP27A1) deficiency, is associated with markedly reduced chenodeoxycholic acid (CDCA), the most powerful activating ligand for farnesoid X receptor (FXR). We investigated the effects of reduced CDCA on FXR target genes in humans. Liver specimens from an untreated CTX patient and 10 control subjects were studied. In the patient, hepatic CDCA concentration was markedly reduced but the bile alcohol level exceeded CDCA levels in control subjects (73.5 vs. 37.8 +/- 6.2 nmol/g liver). Cholesterol 7alpha-hydroxylase (CYP7A1) and Na+/taurocholate-cotransporting polypeptide (NTCP) were upregulated 84- and 8-fold, respectively. However, small heterodimer partner (SHP) and bile salt export pump were normally expressed. Marked CYP7A1 induction with normal SHP expression was not explained by the regulation of liver X receptor alpha (LXRalpha) or pregnane X receptor. However, another nuclear receptor, hepatocyte nuclear factor 4alpha (HNF4alpha), was induced 2.9-fold in CTX, which was associated with enhanced mRNA levels of HNF4alpha target genes, CYP7A1, 7alpha-hydroxy-4-cholesten-3-one 12alpha-hydroxylase, CYP27A1, and NTCP. In conclusion, the coordinate regulation of FXR target genes was lost in CTX. The mechanism of the disruption may be explained by a normally stimulated FXR pathway attributable to markedly increased bile alcohols with activation of HNF4alpha caused by reduced bile acids in CTX liver.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

Pathological findings of bronchiectases caused by Mycobacterium avium intracellulare complex.

It has been argued whether bronchiectasis is truly caused by MAC infection or just a predisposed condition in which MAC colonizes. Our present study was designed to evaluate the pathological findings of bronchiectases caused by Mycobacterium avium intracellulare complex (MAC) lung infection and to demonstrate MAC in the lesion of bronchiectases. A retrospective study was performed in nine cases with positive cultures for MAC in whom lung resections were performed. A determination of whether or not MAC caused pulmonary disease was made using the 1997 criteria required by the American Thoracic Society. In addition, MAC were cultured from all nine lung specimens. Pathological findings of bronchiectases were evaluated in these nine patients. Destruction of bronchial cartilage and smooth muscles layer, obstruction of airway by granulomas, and ulceration of bronchial mucosa were frequently observed. Our present study demonstrates that destruction of fundamental bronchial structure due to extensive granuloma formation throughout the airways was likely the main cause of bronchiectases in MAC infection.

Adult↗
PubMed2002

Immunohistochemical distribution of epithelioid cell, myofibroblast, and transforming growth factor-beta1 in the granuloma caused by Mycobacterium avium intracellulare complex pulmonary infection.

The present study was designed to evaluate the distribution of epithelioid cells, myofibroblasts, and TGF-beta1 in the formation of granuloma caused by Mycobacterium avium intracellulare complex (MAC) lung infection. A retrospective study was performed for 9 cases of positive MAC culture in which lung resections were performed between January 1989 and August 1999. Resected lung specimens were evaluated histologically and immunohistochemically for CD68 (stain for monocytes and macrophages, and epithelioid cells) and alpha-smooth muscle actin as well as vimentin (stain for myofibroblasts), and TGF-beta1 was performed. When granuloma was initially formed, no myofibroblasts were found, but as caseous necrosis appeared, the thin epithelioid cell layer was detected and the outer myofibroblast layer gradually became thick. In the cavitary wall, the layer of epithelioid cells and multinucleated giant cells surrounded necrosis, and was associated with the outer layer of myofibroblasts. In addition, the anti-TGF-beta1 antibody stained the cytoplasm of epithelioid cells and multinucleated giant cells, preceding the advent of myofibroblasts. In summary, our present study evaluated distributions of epithelioid cells, myofibroblasts, and TGF-beta along with the morphogenesis of granuloma, and clearly demonstrated the immunohistochemical difference between granuloma with caseous necrosis and granulomas without caseous necrosis.

Actins↗
PubMed2002

Pathological analysis of the cavitary wall in Mycobacterium avium intracellulare complex pulmonary infection.

OBJECTIVE: The present study was designed to evaluate the process of cavity formation in Mycobacterium avium intracellulare complex (MAC) lung infection, pathologically and clinically. METHODS: Using resected lung specimens, we first evaluated the distribution of MAC as well as the distribution of myofibroblasts in MAC lung infection according to several pathological findings classified as bronchiectasis, centrilobular nodules, cavity, nodules, bronchiolitis, or consolidation. Resected lung specimens (9 cases) were evaluated by special staining: Ziehl-Neelsen's method and immunohistochemically for CD68 (stain for monocytes and macrophages) and alpha-smooth muscle actin (stain for myofibroblasts). Chest CT findings were also examined in these 9 patients. In addition, the serial chest CT scans were reviewed in another 3 patients to evaluate the process of cavity formation, radiologically. RESULTS: Although extensive granuloma formations were observed in every pathological classification, MAC was demonstrated only in the necrotic tissue of the inner surface of the cavitary wall, which was connected to the airway. Myofibroblasts which expressed alpha-smooth muscle actin were intensely demonstrated in the cavitary wall compared with other pathological classifications. In the cavitary wall, the layer of epithelioid cells and multinucleated giant cells surrounded necrosis, and the layer of myofibroblasts surrounded the layer of epithelioid cells. Chest CT findings demonstrated that the cavitary walls were relatively thick. The evaluation of serial chest CT scans demonstrated that cavities were formed from previously existing nodules. CONCLUSIONS: Detection of mycobacteria in the cavitary wall, massive infiltration of myofibroblasts compared with other pathological classifications, and connection to the drainage bronchus, were believed to be important in the process of cavity formation in MAC pulmonary infection.

Adult↗