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Biomedical subjects

Y Urata

Publications and source records attributed to Y Urata.

At least 19 recordsLinked to original sources
PubMed2006

Solitary myofibroma of the lumbar vertebra: adult case.

We present the first known adult case of solitary myofibroma of bone, which affected a lumbar vertebra in a 33-year-old male. Radiography identified a purely lytic lesion with a sclerotic rim in the right pedicle of L1. CT showed an expansile lytic lesion with a sclerotic rim. MRI of the lesion revealed an isointense signal on T1-weighted images, an inhomogeneously hyperintense signal on T2-weighted images, and marked enhancement with gadolinium. Pathological study showed a mixed picture of nodular proliferation of spindle-shaped myoid cells and hemangiopericytomatous proliferation of short spindle/small round cells. The tumor cells were immunoreactive for smooth muscle actin and immunonegative for desmin. This case of solitary myofibroma of bone is exceptionally rare because of its occurrence in an adult older than 20 years of age and its location at an extra-craniofacial site.

Adult↗
PubMed2002

Treatment of asthma patients with herbal medicine TJ-96: a randomized controlled trial.

Alternative medicine use has increased at a remarkable pace all over the world in recent years. Although herbal medicine for the treatment of asthma is becoming the focus of public attention, randomized studies had not been performed, even in Eastern countries including Japan. This study was designed to investigate whether one of the Japanese government approved herbal complexes Saiboku-to (TJ-96) is effective for the treatment of atopic asthma, and to investigate whether this protective activity is associated with a reduction in eosinophilic inflammation. A double-blind, randomized, crossover design was used. Subjects received 2.5 g of TJ-96 or placebo orally 3 times daily for 4 weeks and then, after a washout period of at least 4 weeks, crossed over to receive the alternative treatment. We assessed the effects of pretreatment with TJ-96 on bronchoconstriction precipitated by inhalation of methacholine. Furthermore, eosinophil counts and measurement of eosinophilic cationic protein (ECP) were performed. After 4 weeks of treatment with TJ-96, values of PC20 -methacholine significantly improved in the treatment with TJ-96. Also, patients' symptoms, blood eosinophils, serum ECP, sputum eosinophils, and sputum ECP were significantly decreased. Our results suggest that TJ-96 has an antiinflammatory effect on bronchial eosinophilic infiltration. This study raises further interesting therapeutic possibilities and argues for further trials of new approaches to the treatment of asthma.

Adult↗
PubMed2001

Hammerhead ribozyme against gamma-glutamylcysteine synthetase sensitizes human colonic cancer cells to cisplatin by down-regulating both the glutathione synthesis and the expression of multidrug resistance proteins.

Multidrug resistance in cancer cells is often associated with an elevation in the concentration of glutathione (GSH) and the expression of gamma-glutamylcysteine synthetase (gamma-GCS), a rate-limiting enzyme for GSH. We constructed a hammerhead ribozyme against a gamma-GCS heavy subunit (gamma-GCSh) mRNA transcript and transfected it to human colonic cancer cells (HCT8DDP) resistant to cisplatin (CDDP). The effect of the ribozyme transfection on the drug resistance of cancer cells was studied. (a) Transfection of the ribozyme decreased the GSH level and the efflux of CDDP-GSH adduct, resulting in higher sensitivity of the cells to CDDP. (b) The transfection suppressed the expression of ATP-binding cassette (ABC) family of transporters such as MRP1, MRP2, and MDR1, and stimulated the expression of mutant p53. (c) An electrophoretic mobility shift assay showed that mutant p53 suppresses the SP1-DNA binding activity, suggesting that this mutant p53 is functional and it, in turn, suppresses the expression of ABC transporters. Collectively, transfection of anti-gamma-GCSh ribozyme reduced the synthesis of GSH and the expression of ABC transporters, which causes an increase in the sensitivity of cancer cells to anticancer drugs. Suppression of the SP1-DNA binding activity by p53 may be a factor of down-regulation of ABC transporters.

Antineoplastic Agents↗
PubMed2001

Simultaneous signalling through c-mpl, c-kit and CXCR4 enhances the proliferation and differentiation of human megakaryocyte progenitors: possible roles of the PI3-K, PKC and MAPK pathways.

We assessed the effect of signalling through CXCR4 on the proliferation and differentiation of human megakaryocytic progenitor cells (CFU-Meg) in the presence or absence of stem cell factor (SCF) and/or thrombopoietin (TPO), using peripheral blood-derived CD34(+)IL-6R(-) cells as a target. TPO alone induced a significant number of CFU-Meg colonies. Although stromal cell-derived factor-1 (SDF-1) or SCF alone did not support CFU-Meg colony formation, these factors had a synergistic effect on CFU-Meg colony formation in the presence of TPO. The combination of SDF-1, SCF and TPO induced twice as many CFU-Meg colonies as TPO alone. To investigate the mechanism of this synergistic action, we examined the effects of various protein kinase inhibitors on CFU-Meg colony formation. LY294002 and GF109203X (inhibitors of PI3-K and PKC respectively) completely or partially inhibited this synergistic action. In contrast, a MEK inhibitor (PD98059) did not inhibit CFU-Meg colony formation. It significantly increased the higher ploidy classes (16N to 64N) of megakaryocytes supported by TPO, TPO + SCF, TPO + SDF-1, and TPO + SCF + SDF-1, whereas it abolished the effect of SDF-1 on the increase of higher ploidy classes of megakaryocytes supported by TPO. These results suggest that MAPK may negatively or positively regulate the nuclear maturation of megakaryocytes, known as endomitosis. In the presence of PD98059, proplatelet formation (PPF) was significantly augmented, suggesting that the MAPK pathway may also inhibit the initiation of PPF. In conclusion, simultaneous activation of three signals through c-mpl, c-kit and CXCR4 can induce the in vitro proliferation and differentiation of CFU-Meg, and SDF-1 is a potentiator of human megakaryocytopoiesis.

Cell Cycle Proteins↗
PubMed2001

Alteration of antioxidants during the progression of heart disease in streptozotocin-induced diabetic rats.

Involvement of oxidative stress is implicated in the progression of complication of diabetes mellitus. With respect to heart diseases, we have studied role of oxidative stress/antioxidants using rats treated with streptozotocin to induce diabetes (DM). Hemodynamic and echocardiographic measurements showed thickening of the wall and an increase in the internal dimension of the left ventricle (LV) in DM rats at 8th week. Decrease in diastolic posterior wall velocity and rate of LV pressure change, and increase in LV end diastolic pressures also proved cardiac dysfunction. These changes were further developed in DM rats after 12 weeks. Utilizing rat hearts at 8th and 12th weeks, the following estimations were performed. There was a decrease in the activity of Mn-superoxide dismutase (SOD), suggesting abnormal mitochondrial metabolism of reactive oxygen species. The level of glutathione (GSH) decreased concomitant with a decrease in the expression of gamma-glutamylcysteine synthetase (gamma-GCS). The expression of transforming growth factor-beta1 (TGF-beta1), known as a growth factor and a suppressor of GSH synthesis, elevated in DM rat hearts. Immunohistochemical estimation showed an increase in type IV collagen in DM hearts. Collectively, it was suggested a linkage between mitochondrial damage to generate reactive oxygen species and inactivation of Mn-SOD and elevation of the expression of TGF-beta1 to lead suppression of GSH synthesis and induction of fibrous change for the consequent cardiac dysfunction in DM.

Animals↗
PubMed2001

Doxorubicin-induced DNA intercalation and scavenging by nuclear glutathione S-transferase pi.

Glutathione S-transferase (GST) functions in xenobiotic biotransformation and drug metabolism. Increased expression of GSTpi, an isozyme of GST, has been found in cancer cells resistant to doxorubicin hydrochloride (DOX) or cis-diamminedichloroplatinum (II) (CDDP), and this increase was believed to be correlated with drug resistance of cancer cells. GST is mainly expressed in the cytoplasm; GSTpi in the nucleus has been reported in cancer cells, but the meaning of this result is not known. Here, we studied changes in the amount of nuclear GSTpi after exposure of cancer cells to anticancer drugs, and role of the nuclear GSTpi in drug resistance. We found nuclear GSTpi in cancer cells resistant to DOX, and the amount of nuclear GSTpi was enhanced by treatment of the cancer cells with DOX or CDDP. We also found that a mushroom lectin, an inhibitor of nuclear transport, inhibited the nuclear transfer of GSTpi, suggesting the existence of a specific transport system for the nuclear transfer of GSTpi. Nuclear GSTpi protected DNA against damage by anticancer drugs. These results suggest a possible role of GSTpi in the acquisition of resistance to anticancer drugs by cancer cells.

Antineoplastic Agents↗
PubMed2000

Attenuation of expression of gamma-glutamylcysteine synthetase by ribozyme transfection enhance insulin secretion by pancreatic beta cell line, MIN6.

Low levels of intracellular antioxidant enzyme activities as well as glutathione (GSH) concentrations have been described in pancreatic beta cells. We examined the effects of intracellular GSH depletion on insulin secretion and the role of intracellular GSH in signal transduction in beta cell line, MIN6 cells. Anti-gamma-glutamylcysteine synthetase (gamma-GCS) heavy subunit ribozyme was stably transfected to MIN6 cells to reduce intracellular GSH concentration. In the presence of 10 mM glucose, ribozyme-transfected cells (RTC) increased insulin secretion from 0.58 microg/10(6) cells/h in control cells (CC) to 1.48 microg/10(6) cells/h. This was associated with increased intracellular Ca(2+) concentration in RTC, detected by fluo-3 staining. Our results demonstrated that intracellular GSH concentration might influence insulin secretion by MIN6 cells, and suggest that enhanced insulin secretion by beta cells conditioned by chronic depletion of GSH is mediated by increased intracellular Ca(2+) concentration.

Adenosine Triphosphate↗
PubMed2000

Clonal expansion in evolution of chronic hepatitis to hepatocellular carcinoma as seen at an X-chromosome locus.

Clonal analysis has shown that hepatocellular carcinoma arises from a single cell. However, the clonality of precancerous lesions and adjacent nonneoplastic tissues is not clear. We analyzed a human androgen receptor locus to elucidate the clonal state of liver tissues including post-hepatitic lesions associated with hepatocarcinogenesis. The analysis was based on a restriction fragment length polymorphism involving an androgen receptor locus on the X chromosome, taking advantage of physiologic random inactivation by methylation of 1 of 2 X chromosomes in females during embryogenesis. Clonality was assessed in 79 randomly located tissue samples microdissected from noncirrhotic liver, including a total of 40 morphologically normal sites in 4 normal livers and 39 sites from a single HCV-infected liver. In addition, 51 regenerative nodules, 4 areas of adenomatous hyperplasia, and 18 hepatocellular carcinomas were sampled. All samples were obtained from livers involved by various neoplasms. Eight of forty samples (20.0%) from the four normal livers and 20 of the 39 samples (51.3%) from the single HCV-infected liver showed a monoclonal pattern. Moreover, 30 of 51 regenerative nodules (58.9%) showed a monoclonal pattern. No histologic differences were evident between mono- and polyclonal nodules. On the other hand, the 18 carcinomas and 4 areas of adenomatous hyperplasia all were monoclonal. Mean calculated monoclonal areas of normal liver and liver with chronic hepatitis were 1.1 and 3.3 mm(2). Our results suggest that areas representing a single clone of hepatocytes are present in normal liver, and these progressively expand as changes advance from chronic hepatitis to hepatocellular carcinoma.

Aged↗
PubMed2000

Comparative study of lymphocyte-suppressive potency between prednisolone and methylprednisolone in rheumatoid arthritis.

We compared lymphocyte-suppressive potencies of prednisolone and methylprednisolone in rheumatoid arthritis (RA). IC(50)s of the glucocorticoids (GCs) on concanavalin A-induced blastogenesis of peripheral-blood mononuclear cells (PBMCs) from 44 RA patients and 30 healthy subjects were estimated in vitro, and differences in the IC(50)s of the two GCs were evaluated. The mean (+/-SD) IC(50)s for prednisolone and methylprednisolone on PBMC-blastogenesis of RA were 17.2+/-17.1 and 12.6+/-18.4 ng/ml, respectively, and no significant differences were observed between prednisolone-IC(50) and methylprednisolone-IC(50). In contrast, the mean IC(50)s of prednisolone and methylprednisolone on healthy PBMCs were 19.4+/-22. 4 and 3.7+/-3.9 ng/ml, respectively, and thus methylprednisolone potency was significantly higher than prednisolone potency (p<0.01). Methylprednisolone potency against PBMCs in RA patients exhibiting a high level of rheumatoid factor (RF) (>20 IU/ml) and the rheumatoid arthritis particle-agglutination value (RAPA) (>80) was significantly higher than that of patients exhibiting a lower level of RF or RAPA (p<0.05). In prednisolone-IC(50), however, such differences between the two patient-subgroups were not observed. Unlike reported cases of renal transplantation and healthy subjects, there was no difference in the lymphocyte-suppressive potencies for both prednisolone and methylprednisolone on RA-PBMCs. However, PBMCs from RA patients exhibiting high levels of RF or RAPA are more sensitive to methylprednisolone rather than prednisolone.

Aged↗
PubMed2000

Obesity-sleep apnea (Pickwickian) syndrome: autopsy findings and a medicolegal review.

A 24-year-old obese woman was found dead in her boyfriend's apartment in his absence. She had been admitted to the hospital six times previously because of diminished consciousness, respiratory failure, and pneumonia. A diagnosis of obesity-sleep apnea (Pickwickian) syndrome was made. An autopsy showed that she had an extremely small larynx, intra-alveolar hemorrhage, edema, pulmonary lymphocyte infiltration, and severe focal myocardial fibrosis. No fresh myocardial lesion, coronary arterial lesion, or findings of heart failure were seen. The woman's elder sister had also died of the same disease at the age of 23. The cause of death was diagnosed as respiratory failure and pneumonia with the sleep-apnea syndrome as the underlying cause of death. Although no autopsy reports of the sleep-apnea syndrome have been published in the field of forensic pathology, this syndrome is a predominant cause of sudden death in obese persons and could be a hidden cause of accidental death in such persons.

Journal Article↗
PubMed2000

A long-term survival case of multiple hepatocellular carcinoma with metachronous lymph node metastasis.

A long-term survival case of multiple hepatocellular carcinoma (HCC) with metachronous metastasis to a lymph node is reported. The patient, a 66-year-old woman, had two primary HCC nodules, one each in the left and right hepatic lobes, which were resected. She developed a lymph node lesion and a secondary HCC 45 and 62 months after the first operation, respectively. She has been well for the 7 years since the first operation despite undergoing hepatic resection for HCC twice as well as lymph node resection. Clonal analysis, based on the methylation pattern of the X chromosome-linked androgen receptor gene, suggested that the two primary tumors were multicentric and that the lymph node lesion had arisen by metastasis from the primary tumor in the right hepatic lobe.

Journal Article↗
PubMed2000

Mitogen-activated protein kinase, ERK1/2, is essential for the induction of vascular endothelial growth factor by ionizing radiation mediated by activator protein-1 in human glioblastoma cells.

Vascular Endothelial Growth Factor (VEGF)/Vascular Permeability Factor plays an important role in angiogenesis and cell proliferation of cancer cells. Glioblastoma cells are most malignant and show resistance to radiation therapy inducing VEGF to cause angiogenesis and brain edema. In the present study, the regulatory mechanism of the expression of VEGF by ionizing radiation was studied in three human glioblastoma cells. Induction of VEGF mRNA by ionizing radiation was dependent on dose and incubation time. Activator protein-1 (AP-1) was activated by 10 Gy of ionizing radiation in 1 h in T98G glioblastoma cells on an electrophoretic mobility shift assay. We constructed chimeric genes containing various regions of the VEGF promoter gene and the coding region for chloramphenicol acetyltransferase (CAT) and transiently transfected them to T98G cells. CAT assay with the VEGF promoter gene containing an AP-1 site demonstrated that the promoter activity of the VEGF gene was enhanced by ionizing radiation. Immunological analysis of the activity of mitogen-activated protein kinase, ERK1/2, showed that this activity is up-regulated by ionizing radiation. These results suggest that ERK1/2 pathway is involved in the up-regulation of VEGF expression ionizing radiation mediated by AP-1, which may lead to further neovascularization and proliferation of glioblastoma cells resistant to radiation therapy.

Blotting, Northern↗
PubMed1999

Co-expression of gamma-glutamylcysteine synthetase sub-units in response to cisplatin and doxorubicin in human cancer cells.

Glutathione (gamma-glutamylcysteinyl glycine, GSH) is believed to be important in the acquisition of resistance to anti-cancer drugs such as cisplatin (CDDP) and doxorubicin (DOX). gamma-Glutamylcysteine synthetase (gamma-GCS) is a key enzyme for maintaining intracellular GSH levels; it is composed of a catalytic heavy (gamma-GCSh) and a regulatory light (gamma-GCSl) sub-unit. In the present study, the expression of gamma-GCS sub-units was examined in human cancer cell lines. The levels of GSH, the expression of gamma-GCSh and gamma-GCSl mRNAs and proteins in human cancer cells were higher in CDDP-resistant cells and DOX-resistant cells than in the drug-sensitive cells. Treatment of CDDP/DOX-resistant human colonic-cancer cells (HCT8DDP) with CDDP and DOX caused simultaneous induction of the expression of gamma-GCSh and gamma-GCSl mRNAs. The transcriptional regulation of gamma-GCS was studied and it was observed that the DNA-binding activity of activator protein 1 (AP-1) is induced by CDDP and DOX using an electrophoretic mobility shift assay. We constructed chimeric genes containing various regions of the gamma-GCSh-promoter gene and the coding region for luciferase. The HCT8DDP cells transiently transfected with a plasmid containing an AP-1 site of the gamma-GCSh-promoter-luciferase construct showed increased luciferase activity when treated with CDDP and DOX. These results suggest that stimulation of the expression of gamma-GCSh by CDDP and DOX is mediated by AP-1, which relates to the resistance of cancer cells to the drug.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Protective role of glutathione synthesis in response to oxidized low density lipoprotein in human vascular endothelial cells.

Impairment of endothelial cells by oxidized low density lipoprotein (OxLDL) is believed to be the first step in atherogenesis. It is also believed that oxidative stress/antioxidant imbalance is involved in the cell damage by OxLDL. However, little is known about the interaction between OxLDL and antioxidants. In this study, we show that treatment of human vascular endothelial cells with OxLDL caused a gradual increase of glutathione (gamma-glutamylcysteinyl glycine, GSH) levels in 24 h. OxLDL increased the intracellular levels of reactive oxygen species (ROS) and stimulated the expression of gamma-glutamylcysteine synthetase (gamma-GCS), the rate-limiting enzyme for the GSH synthesis, the mitogen-activated protein kinase (MAPK) activity, and the AP-1-DNA binding activity. The luciferase activity of gamma-GCS promoter containing AP-1 site was activated by OxLDL. Collectively, OxLDL induces gamma-GCS expression mediated by AP-1 resulting in an increase of GSH levels. The MAPK activity stimulated by ROS may be involved in the activation of AP-1. The increase in GSH by OxLDL may afford cellular protection against OxLDL-induced oxidative stress.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1999

Melatonin induces gamma-glutamylcysteine synthetase mediated by activator protein-1 in human vascular endothelial cells.

In the present study, we show that melatonin induces the expression of gamma-glutamylcysteine synthetase (gamma-GCS), the rate-limiting enzyme of glutathione (GSH) synthesis, in ECV304 human vascular endothelial cells. One micromolar melatonin induced the expression of gamma-GCS mRNA followed by an increase in the concentration of GSH with a peak at 24 h. An electrophoretic mobility shift assay showed that melatonin stimulates the DNA-binding activity of activator protein-1 (AP-1) as well as retinoid Z receptor/retinoid receptor-related orphan receptor alpha (RZR/RORalpha). ECV304 cells transiently transfected with a plasmid containing the gamma-GCS promoter-luciferase construct showed increased luciferase activity when treated with melatonin. The melatonin-dependent luciferase activity was found in the gamma-GCS promoter containing AP-1 site. The luciferase activity mediated by AP-1 was repressed in the promoter containing RZR/RORalpha site. In addition, cell cycle analysis showed that melatonin increases the number of cells in the G0/G1 phase; however, treatment of the cells with buthionine sulfoximine, a specific inhibitor of gamma-GCS, abolished the effect of melatonin on the cell cycle, suggesting induction of cell arrest by melatonin requires GSH. As conclusion, induction of GSH synthesis by melatonin protects cells against oxidative stress and regulates cell proliferation.

Buthionine Sulfoximine↗
PubMed1999

Regulation of gamma-glutamylcysteine synthetase expression in response to oxidative stress.

Glutathione (GSH) is synthesized by the activity of two ATP-requiring GSH synthesizing enzymes. Gamma-glutamylcysteine synthetase (gamma-GCS) is the rate limiting enzyme for the GSH synthesis. Gamma-GCS is a heterodimer of heavy, catalytic subunit and light, regulatory subunit and responsive to many stresses, such as heat shock, oxidative stress or cytokines. To know the regulation of the expression of gamma-GCS gene, in the present study, we show evidences that gamma-GCS heavy subunit is upregulated by oxidative stress by ionizing radiation and TNF-alpha mediated by nuclear factor-kappaB (NF-kappaB), and impairment of the expression of gamma-GCS by TNF-alpha in diabetic condition. Furthermore we describe the importance of GSH in the regulation of NF-kappaB subunits.

Animals↗
PubMed1999

Significance of glutathione-dependent antioxidant system in diabetes-induced embryonic malformations.

Hyperglycemia-induced embryonic malformations may be due to an increase in radical formation and depletion of intracellular glutathione (GSH) in embryonic tissues. In the past, we have investigated the role of the glutathione-dependent antioxidant system and GSH on diabetes-related embryonic malformations. Embryos from streptozotocin-induced diabetic rats on gestational day 11 showed a significantly higher frequency of embryonic malformations (neural lesions 21.5 vs. 2.8%, P<0.001; nonneural lesions 47.4 vs. 6.4%, P<0.001) and growth retardation than those of normal mothers. The formation of intracellular reactive oxygen species (ROS), estimated by flow cytometry, was increased in isolated embryonic cells of diabetic rats on gestational day 11. The concentration of intracellular GSH in embryonic tissues of diabetic pregnant rats on day 11 was significantly lower than that of normal rats. The activity of y-glutamylcysteine synthetase (gamma-GCS), the rate-limiting GSH synthesizing enzyme, in embryos of diabetic rats was significantly low, associated with reduced expression of gamma-GCS mRNA. Administration of buthionine sulfoxamine (BSO), a specific inhibitor of gamma-GCS, to diabetic rats during the period of maximal teratogenic susceptibility (days 6-11 of gestation) reduced GSH by 46.7% and increased the frequency of neural lesions (62.1 vs. 21.5%, P<0.01) and nonneural lesions (79.3 vs. 47.4%, P<0.01). Administration of GSH ester to diabetic rats restored GSH concentration in the embryos and reduced the formation of ROS, leading to normalization of neural lesions (1.9 vs. 21.5%) and improvement in nonneural lesions (26.7 vs. 47.4%) and growth retardation. Administration of insulin in another group of pregnant rats during the same period resulted in complete normalization of neural lesions (4.3 vs. 21.5%), nonneural lesions (4.3 vs. 47.4%), and growth retardation with the restoration of GSH contents. Our results indicate that GSH depletion and impaired responsiveness of GSH-synthesizing enzyme to oxidative stress during organogenesis may have important roles in the development of embryonic malformations in diabetes.

Animals↗