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H Koga

Publications and source records attributed to H Koga.

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

Involvement of p21(WAF1/Cip1), p27(Kip1), and p18(INK4c) in troglitazone-induced cell-cycle arrest in human hepatoma cell lines.

Peroxisome proliferator-activated receptor gamma (PPARgamma) regulates cell growth and differentiation. Recent evidence has suggested that PPARgamma ligands had anti-tumor effects through inhibiting cell growth and inducing cell differentiation in several types of malignant neoplasm. In the present study, we investigated: 1) the expression of PPARgamma in both human hepatoma cell lines and 5 resected human hepatocellular carcinoma (HCC) tissues; 2) the growth-inhibitory effect of troglitazone, a PPARgamma ligand, on those hepatoma cells; and 3) the molecular mechanisms of troglitazone-induced cell-cycle arrest. Five hepatoma cell lines, HLF, HuH-7, HAK-1A, HAK-1B, and HAK-5, were used. The mRNA expression levels of PPARgamma, p21(WAF1/Cip1), and p27(Kip1) were determined by real-time quantitative reverse transcription-polymerase chain reaction. The expression of cell cycle-regulating proteins, such as p21, p27, p18(INK4c), cyclin E, and pRb, was examined using Western blotting. PPARgamma was constitutively expressed in all the cell lines and the HCC tissues used in this study. A cytostatic effect of troglitazone was found in those cell lines, and this inhibition of cell growth was dosage-dependent. G0/G1 arrest was apparently demonstrated in flow cytometric analysis in HLF, HAK-1A, HAK-1B, and HAK-5, all of which showed an increased expression of p21 protein. However, HuH-7, lacking p21 protein expression, did not demonstrate clear arrest in the cell-cycle analysis. HLF, which was deficient in the protein product of the retinoblastoma tumor-suppressor gene (pRb), responded most profoundly to troglitazone, showing an increased expression in not only p21, but also in p27 and in p18. These findings suggested that p21, p27, and p18 might be involved in troglitazone-induced cell-cycle arrest in human hepatoma cells.

CDC2-CDC28 Kinases↗
PubMed2001

Alterations in tight junctions differ between primary biliary cirrhosis and primary sclerosing cholangitis.

Tight junctions (TJ) of biliary epithelial cells (BEC) and hepatocytes prevent bile regurgitation from the biliary tract. Alterations in these TJs may participate in chronic cholestatic liver diseases such as primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). We examined the localization of 2 TJ proteins, ZO-1 and 7H6, in these diseases. Frozen sections from livers of PBC, PSC, extrahepatic cholestasis (Ex-C), and hepatitis C-associated cirrhosis (LC-C), as well as histologically normal livers, were processed for double-fluorescence immunohistochemistry. In controls and cirrhosis, 7H6 and ZO-1 colocalized surrounding the luminal space of the bile ducts and outlined the bile canalicular spaces between hepatocytes. In untreated PBC, immunostaining for ZO-1 in BEC of bile ducts 40 to 80 microm in diameter was preserved, but that for 7H6 was diminished to absent. In PBC treated with ursodeoxycholic acid (UDCA), immunostaining for 7H6 was well preserved. In PSC as well as in Ex-C, immunostaining for both 7H6 and ZO-1 was well preserved in bile ducts. In hepatocytes, ZO-1 showed preserved immunoreactivity, but immunostaining for 7H6 frequently disappeared. The percentage of bile ducts with immunostaining for 7H6 in all bile ducts with immunostaining for ZO-1 was significantly reduced in PBC compared with that in control, LC-C, Ex-C, and PSC (all P <.0001). Substantial alteration in the TJ protein occurs predominantly in bile ducts in PBC and in hepatocytes in PSC, suggesting increased paracellular permeability along different paracellular routes for bile regurgitation in these chronic cholestatic liver diseases.

Adolescent↗
PubMed2001

[Clinical significance of eosinophilic cationic protein in serum and bronchoalveolar lavage fluid of adult patients with mycoplasmal pneumonia].

Pathogenic mechanisms of mycoplasmal pneumonia is not fully understood at present though some kind of cell-mediated hypersensitivity is closely related to its mechanisms. Though eosinophilia in peripheral blood are sometimes revealed in patient with mycoplasmal pneumonia, it is not unclear whether eosinophils related to its pathogenesis, or not. We evaluated the clinical significance of ECP in serum and BAL fluid in patients with mycoplasmal pneumonia. The diagnosis of mycoplasmal pneumonia was confirmed both by serological diagnosis from paired serum and by the polymerase chain reaction (PCR) methods using specific primers of the Mycoplasma pneumoniae for detecting specific DNA from bronchial washing fluids. ECP level in serum were measured in 27 patients (11 male, 16 female, average age 31.7 yo) with mycoplasmal pneumonia by ELISA methods. ECP level in BALF were also measured in ten of all patients. The level of ECP in serum was high in 17 cases (63%) of the total cases. In addition the level of ECP in BALF was also high in all tested patients (10 cases). There was a correlation between serum ECP level and days from onset. There was also a correlation between serum ECP level and WBC counts, the degree of PaO2. These results suggested that ECP derived from activated eosinophils in the lung might in part play a role in the pathogenesis of mycoplasmal pneumonia.

Adult↗
PubMed2001

Functional impact of human collagen alpha2(XI) gene polymorphism in pathogenesis of ossification of the posterior longitudinal ligament of the spine.

Ossification of the posterior longitudinal ligament (OPLL) of the spine is the leading cause of myelopathy in Japan. In earlier studies, we provided genetic linkage and allelic association evidence of distinct differences in the human collagen alpha2(XI) gene (COL11A2) that might constitute inherited predisposition to OPLL. In the present study, a strong allelic association with non-OPLL (p = 0.0003) was observed with an intron 6 polymorphism [intron 6 (-4A)], in which the intron 6 (-4A) allele is more frequently observed in non-OPLL subjects than in OPLL patients. In addition, a newly identified polymorphism in exon 6 [exon 6 (+28A)] was in linkage disequilibrium with the intron 6 (-4A). The functional impact of the polymorphisms was analyzed by comparing the differences in messenger RNA (mRNA) splicing by reverse-transcription polymerase chain reaction (RT-PCR) analysis in cultured cells from the interspinous ligament and an in vitro exon trapping study. The intron 6 (-4A) allele resulted in skipping exon 6 and retaining exon 7, while the exon 6 (+28A) allele was not associated with alteration in mRNA splicing. Similar mRNA species were observed in undifferentiated osteoblast (Ob) cells and in cells from posterior longitudinal ligament of non-OPLL subjects. The region containing exons 6-8 is an acidic subdomain presumably exposed to the surface that could interact with molecules of the extracellular matrix. Accordingly, retaining exon 7 together with removal of exon 6 observed in intron 6 (-4A) could play a protective role in the ectopic ossification process because the same pattern was observed in undifferentiated Ob cells and nonossified posterior longitudinal ligament cells.

Alternative Splicing↗
PubMed2001

Element concentrations in urine of patients suffering from chronic arsenic poisoning.

In order to know the element levels in the urine of patients with chronic arsenic poisoning caused by arsenic assimilated from burning coal via air and food, we investigated various elements in the urine of 16 patients with this disease and 16 controls living in the same county in Guizhou Province of China. Concentrations of 25 elements (Al, As, Ba, Be, Bi, Ca, Cd, Cr, Cu, Fe, Ga, Mg, Mn, Mo, Ni, P, Pb, Rb, Sb, Se, Sn, Sr, Ti, V and Zn) were determined by an inductively coupled plasma mass spectrometer or an inductively coupled plasma atomic emission spectrometer. The average concentrations of Cu, Ga and Sn as well as As in the patients were significantly higher, and those of Cr, Rb, Sr and Ti in the patients were significantly lower than the control values. Al, Ba, Mn, Ni and Se were under detection limit in the patients, though they could be detected in the controls. There were no positive correlations between the concentration of As and the concentrations of other elements, including Cu, Ga and Sn in the patients. The results of this study suggest that As from burning coal might influence the urinary excretion of some elements.

Adult↗
PubMed2001

Relation of type II transforming growth factor-beta receptor to hepatic fibrosis and hepatocellular carcinoma.

Hepatocarcinogenesis is closely related to hepatic fibrosis. In this study, we investigated the relationship of type II transforming growth factor-beta receptor (T beta RII) to hepatic fibrosis and hepatocellular carcinoma (HCC). In vivo: liver tissues were obtained from 30 patients (10 chronic hepatitis, 7 cirrhosis, 13 HCC). Protein expression and immunolocalization of T beta RII were examined by Western blot analysis and immunohistochemistry. In vitro: T beta RII protein expression in hepatoma cell lines (HepG2, Hep3B, HLE, HLF and Huh7) was examined by Western blot analysis. Next, we transfected T beta RII cDNA to Huh7, and compared the change of cell number and observed the induction of apoptosis after TGF-beta1 treatment using a FACScan flow cytometer. In vivo: T beta RII immunolocalization in liver tissues was significantly decreased in patients with HCC compared with that of patients with chronic hepatitis or liver cirrhosis. In Western blot analysis, T beta RII expression in tissues attenuated in comparison with that in non-tumor tissues in some patients with HCC. In vitro: T beta RII protein expression in HLE, HLF and Huh7 cells was weaker than that in HepG2 and Hep3B cells. In Huh7 cells transfected T beta RII cDNA, cell arrest and apoptosis were obviously induced. These results indicated that human HCC has a reduced expression of T beta RII for TGF-beta1. This may provide a selective growth advantage to HCC to escape the inhibitory growth signals of TGF-beta1, and may be linked with critical steps in the growth of hepatoma cells.

Aged↗
PubMed2001

[Multiple brain abscesses associated with Rendu-Osler-Weber disease: report of two cases].

Two cases of multiple brain abscesses associated with congenital pulmonary arteriovenous fistula are reported. A 57-year-old male with Rendu-Osler-Weber disease complicated by pulmonary arteriovenous fistula developed multiple brain abscesses in the right parietal region. He responded well to surgical drainage and antibiotic therapy, and the pulmonary arteriovenous fistula, located in the left lower lobe, was resected. A 26-year-old female with Rendu-Osler-Weber disease complicated by pulmonary arterivenous fistula developed recurrent multiple brain abscesses in both the frontal and right parietal regions. The brain abscesses were successfully treated with aspiration and antibiotic therapy. She had a history of two previous brain abscesses in the right parietal regions that were excised on separate occasions at 16 and 23 years of age. Although pulmonary arteriovenous fistula was confirmed by angiography, in this case surgical removal of the pulmonary lesions was not indicated due to multiple vascular shunting. The patient had no recurrence of brain abscess with oral antibiotic therapy.

Adult↗
PubMed2001

[Intracranial occlusion of the internal carotid artery after minor closed head injury].

Thrombosis of the extracranial portion of the internal carotid artery as a result of nonpenetrating head and neck injury is not uncommon. However, intracranial occlusion of the internal carotid artery after minor head and neck injury without skull fracture is rare. We report a case of 14-year-old male who suffered a minor head injury during an athletic meeting of his school and developed a right hemiparesis and a lethargy state resulting from thrombosis of the supraclinoid portion of the left internal carotid artery. On admission, skull films and a CT scan revealed no abnormality. One hour later, he fully recovered. One day later, no definite lesions were detected on T1-weighted and T2-weighted image of MRI, but an abnormal high signal lesion in the left frontal lobe was detected on diffusion-weighted image of MRI. On additional MR angiography, intracranial occlusion of the internal carotid artery due to dissection was demonstrated.

Adolescent↗
PubMed2000

Interaction of the Unc-51-like kinase and microtubule-associated protein light chain 3 related proteins in the brain: possible role of vesicular transport in axonal elongation.

We identified two mammalian ULK1 (Unc-51-like kinase involved in neurite extension) binding proteins by yeast two-hybrid screening. Both proteins showed high structural similarity to microtubule-associated protein (MAP) light chain 3 (LC3). One is identical to the Golgi-associated ATPase Enhancer of 16 kDa (GATE-16), an essential factor for intra-Golgi transport [39]. The other is identical to the gamma 2-subunit of GABA-A receptor associated protein (GABARAP) which has a possible role in receptor transport [46]. Using the yeast two-hybrid system and the in vitro GST pull-down assay, we found that the N-terminal proline/serine rich (PS) domain of ULK1 (amino acid 287-416) is required for ULK1-GATE-16 and ULK1-GABARAP protein interactions. However, the kinase activity of ULK1 affected neither ULK1-GATE-16 nor ULK1-GABARAP interaction. Immunohistochemical analysis using ULK1 and GABARAP antibodies showed that the ULK1 and the GABARAP proteins co-localized to many kind of neurons such as pyramidal cells of the hippocampus, mitral cells of the olfactory bulb, and Purkinje cells of the cerebellum. In HeLa cells, endogenous ULK1 and tagged GABARAP showed punctate structures in the cytosol, and were colocalized. These results suggest that the interaction of ULK1 and GABARAP is important to vesicle transport and axonal elongation in mammalian neurons.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Dialysis-related spinal canal stenosis: a clinicopathological study on amyloid deposition and its AGE modification.

Three cases operated for spinal canal stenosis induced by dialysis-related amyloidosis (DRA) were investigated clinicopathologically. Cases were all-male, and had undergone hemodialysis around 20 years. In two cases, cervical plain X-rays showed only minor spondylotic changes. However, magnetic resonance imaging (MRI), myelography, and computed tomography (CT) showed extradural thickness with compression on the cervical spinal cord and cauda equina. In one case cervical X-rays showed typical destructive spondyloarthropathy (DSA), and MRI showed compression myelopathy. Surgical treatment on both cervical and lumbar spine in two cases and on cervical spine only in one case successfully reduced the symptoms. Extradural thickened tissue and ligament flavum obtained during surgery were studied histopathologically and immunostained by using anti-CD68, anti-beta2-microglobulin (beta2m), and anti-advanced glycation end product (AGE) antibody. Congo red stain showed diffuse or nodular amyloid deposition, and immunostaining with anti-beta2m and anti-AGE antibodies also demonstrated the same distribution pattern. Thus, beta2m-positive amyloid tissue in the extradural thickness (extradural amyloid deposition) was immunohistochemically demonstrated to be modified with AGE. Inflammatory reaction with histiocytic and giant cell infiltration was also shown around the amyloid tissues. There were CD68-positive cells, and some cells were positive for AGE and beta2m. These findings suggest that beta2m accumulation and inflammatory reaction finally promote destruction of connective tissues. MRI, CT and/or myelography are necessary for diagnosing spinal canal stenosis accompanied by DRA. In conclusion, we propose a more comprehensive concept of dialysis-related spinal canal stenosis, which includes both DSA and myeloradiculopathy induced by extradural thickness.

Amyloid↗
PubMed2000

Copper does not alter the intracellular distribution of ATP7B, a copper-transporting ATPase.

Wilson's disease is a genetic disorder characterized by the accumulation of copper in the body due to a defect of biliary copper excretion. However, the mechanism of biliary copper excretion has not been fully clarified. We examined the effect of copper on the intracellular localization of the Wilson disease gene product (ATP7B) and green fluorescent protein (GFP)-tagged ATP7B in a human hepatoma cell line (Huh7). The intracellular organelles were visualized by fluorescence microscopy. GFP-ATP7B colocalized with late endosome markers, but not with endoplasmic reticulum, Golgi, or lysosome markers in both the steady and copper-loaded states. ATP7B mainly localized at the perinuclear regions in both states. These results suggest that the main localization of ATP7B is in the late endosomes in both the steady and copper-loaded states. ATP7B seems to translocate copper from the cytosol to the late endosomal lumen, thus participating in biliary copper excretion via lysosomes.

Adenosine Triphosphatases↗
PubMed2000

Identification of genomic DNA sequences bound by mutant p53 protein (Gly245-->Ser) in vivo.

Mutant p53 proteins were shown to exert complex DNA-interactions in vitro, like binding to MAR-DNA, but so far it is unknown whether such interactions also occur in vivo. Therefore we analysed the binding of mutant (mut) p53 (Gly245-->Ser) in Onda 11 glioma cells to cellular DNA in vivo, using p53-specific chromatin immunoprecipitation (CHIP) after in vivo cross-linking of mut p53 to genomic DNA with cisplatin. We identified genomic DNA fragments to which mut p53 (Gly245-->Ser) could be cross-linked in vivo. Purified recombinant mut p53 (Gly245-->Ser) was able to bind specifically to such elements in PCR-EMSA in vitro, supporting the idea that this mut p53 protein interacts with genomic DNA in vivo. The genomic DNA fragments identified are vastly different in sequence, but display as a common feature a high likelihood to adopt a non B-DNA conformation. Therefore we propose that structural determinants within these DNA elements are important for their interaction with mut p53 (Gly245-->Ser) in vivo. Oncogene (2000) 19, 4178 - 4183

Amino Acid Substitution↗
PubMed2000

Results of a longer than 10-year follow-Up of patients with rheumatoid arthritis treated by occipitocervical fusion.

STUDY DESIGN: Evaluation of results a longer than 10-year follow-up of patients with upper cervical lesions due to rheumatoid arthritis who underwent occipitocervical fusion. OBJECTIVE: To determine the final outcome of patients with upper cervical lesions due to rheumatoid arthritis treated by occipitocervical fusion. SUMMARY OF BACKGROUND DATA: There are few studies reporting the final outcome of patients with rheumatoid arthritis treated by occipitocervical fusion and observed for longer than 10 years. METHODS: The subjects were 16 patients with rheumatoid arthritis with myelopathy who underwent occipitocervical fusion with a rectangular rod more than 10 years ago. All 16 patients had irreducible atlantoaxial dislocation, and 11 also had vertical dislocation of the axis. All patients had preoperative nuchal pain, and were classified into Class II (two patients), Class IIIA (nine patients), and class IIIB (five patients) according to Ranawat's preoperative neurologic classification. RESULTS: The atlas-dens interval remained the same as immediately after surgery. Vertical dislocation returned to the preoperative condition, despite successful surgical correction. Preoperative occipital pain disappeared or was reduced in all cases. Myelopathy improved in 12 of the 16 patients (75%) by more than one class in the Ranawat preoperative neurologic classification. Survival rate at 10 years after surgery was 38%; mean age at death was 70.7 years. The postoperative periods during which patients could walk by themselves ranged from 6 months to 13 years (mean, 7.5 years). CONCLUSIONS: Occipitocervical fusion for patients with rheumatoid arthritis is useful for decreasing nuchal pain, reducing myelopathy, and improving prognosis.

Aged↗
PubMed2000

Cigarette smoking, CYP1A1 MspI and GSTM1 genotypes, and colorectal adenomas.

Cigarette smoking has been related to increased risk of colorectal adenomas, but the underlying mechanisms are unknown. Genetic polymorphisms are known for enzymes involved in the activation of polycyclic aromatic hydrocarbons and other tobacco-related carcinogens. Polycyclic aromatic hydrocarbons are activated by cytochrome P4501A1 (CYP1A1) and detoxified by glutathione S-transferases. We investigated the relation of CYP1A1 MspI and GSTM1 genotypes to the risk of colorectal adenomas with special reference to interaction with cigarette smoking among 205 cases of colorectal adenomas and 220 controls with normal total colonoscopy in a male Japanese population. Cigarette smoking was strongly associated with increased risk of colorectal adenomas. Overall, neither the CYP1A1 MspI genotype nor the GSTM1 genotype was related to colorectal adenomas. A significant trend for increased risk of colorectal adenomas associated with smoking was observed for each of the CYP1A1 MspI genotypes, and the increasing trends did not differ by MspI genotype. The positive association between smoking and colorectal adenomas did not vary much with GSTM1 genotypes. Among former and current smokers, adenoma risk did not differ according to the combination of CYP1A1 MspI and GSTM1 genotypes. CYP1A1 MspI and GSTM1 genotypes do not seem to modify the risk of colorectal adenomas associated with cigarette smoking.

Adenoma↗
PubMed2000

NE-dlg, a mammalian homolog of Drosophila dlg tumor suppressor, induces growth suppression and impairment of cell adhesion: possible involvement of down-regulation of beta-catenin by NE-dlg expression.

Membrane-associated guanylate kinases (MAGUKs) are known to function as scaffolds for forming multiprotein complexes at the synaptic junctions of neuronal cells and at sites of epithelial cell-cell contact. In Drosophila, mutations of the lethal (1)-discs large (dlg) gene, which encodes a MAGUK protein, leads to post-synaptic structure defects in neuronal cells and neoplastic overgrowth of epithelial cells. We previously showed that NE-dlg (neuronal and endocrine dlg), a human homolog of the dlg, plays a crucial role in formation of synaptic structure in human neuronal cells. Here we demonstrate that NE-dlg, similar to Drosophila dlg, is involved in regulation of cell cycle progression and adhesive ability of non-neuronal cells. Overexpression of NE-dlg in proliferating cells including various cancer cell lines induced growth suppression and impairment of cell adhesive ability. Furthermore, NE-dlg overexpression caused the down-regulation of beta-catenin in cancer cells regardless of mutations in the APC (adenomatous polyposis coli) gene. The PDZ domains of NE-dlg were found to be essential for the growth suppression, loss of adhesive property and down-regulation of beta-catenin. We propose that NE-dlg regulates the cell growth and adhesive ability by controlling the level of beta-catenin through an APC-independent pathway. Inactivation of NE-dlg may therefore contribute to development and/or progression of human neoplasms.

Adaptor Proteins, Signal Transducing↗