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T Ohno

Publications and source records attributed to T Ohno.

At least 127 records · Page 7Linked to original sources
PubMed2000

Ectopic expression of c-myc fails to overcome downregulation of telomerase activity induced by herbimycin A, but ectopic hTERT expression overcomes it.

Telomerase plays a key role in the maintenance of chromosomal stability in tumors, but the mechanism regulating telomerase activity is still unclear. Recent studies have suggested that c-myc may be vital for regulation of hTERT mRNA expression and telomerase activity. In this study, we investigated the changes of telomerase activity and telomerase-related genes induced by herbimycin A in K562 human chronic myelogeous leukemic cells. Telomerase activity showed a biphasic pattern in herbimycin A-treated K562 cells. Initially, the telomerase activity decreased along with the decline of cells in S and G2/M phases, but it recovered slightly at the end of treatment. Expression of mRNA for the telomerase catalytic subunit (hTERT) was decreased before the decline of telomerase activity, and increased slightly before the reactivation of telomerase activity. During herbimycin A treatment, both c-myc and cyclin D1 mRNA showed transient downregulation before the increase of G1 cells. Herbimycin A treatment caused the downregulation of both telomerase activity and hTERT mRNA in cyclin D1-transfected K562 cells, while telomerase activity was partially restored in c-Myc-transfected cells. In contrast, hTERT-transfected K562 cells maintained a high level of telomerase activity during herbimycin A treatment. Neither the template RNA component of telomerase (hTERC) nor telomerase-associated protein (TEP-1) were altered in any of the transfected K562 cells. These results indicate that telomerase activity is mainly regulated by hTERT, and that c-Myc protein is one of the positive regulators of hTERT in leukemic cells but is not enough to counteract the downregulation of telomerase activity by herbimycin A completely.

Benzoquinones↗
PubMed2000

Mechanism of prevention by capsaicin of ethanol-induced gastric mucosal injury--a study in the rat using intravital microscopy.

BACKGROUND: Capsaicin acts specifically on primary afferent neurones to release neuropeptides, including calcitonin gene-related peptide (CGRP), and prevents ethanol-induced mucosal injury. AIM: To investigate the microvascular changes in the gastric mucosa in response to ethanol using intravital microscopy to elucidate the mechanism of capsaicin-induced gastroprotection. METHODS: The posterior gastric wall in the rat was secured in an observation chamber and perfused with Tyrode's solution. The microcirculation was observed through a window made by removing a limited area of smooth muscle. RESULTS: Ethanol (50%) applied to the mucosa constricted the collecting venules and venules but dilated arterioles. The constriction of the collecting venules resulted in mucosal congestion, which caused mucosal injury. Application of capsaicin to the mucosa dilated the arterioles but not the collecting venules or venules. Arteriolar dilation was inhibited by a CGRP antagonist, CGRP-(8-37). Prior application of capsaicin prevented ethanol-induced constriction of the collecting venules, and the action of capsaicin was inhibited by prior application of CGRP-(8-37). CONCLUSIONS: The results suggest that the inhibition of ethanol-induced gastric injury by capsaicin is attributable to the suppression of collecting venule constriction, via CGRP release.

Animals↗
PubMed2000

Decreased insulin production and increased insulin sensitivity in the klotho mutant mouse, a novel animal model for human aging.

We have recently identified a novel gene, klotho (kl), which may suppress several aging phenotypes. A defect of kl gene expression in the mouse results in a syndrome resembling human aging, such as arteriosclerosis, skin atrophy, osteoporosis, and pulmonary emphysema. To determine whether mouse homozygotes for the kl mutation (kl/kl) show abnormal glucose metabolism, an oral glucose tolerance test (OGTT) was performed at 6 to 8 weeks of age. Blood glucose levels during the OGTT were significantly lower in kl/kl mice versus wild-type mice. The insulin content of the pancreas was significantly lower in kl/kl mice compared with wild-type mice. Decreased insulin production was also supported by Northern blot analysis showing lower levels of insulin mRNA in kl/kl mice. To examine how lower blood glucose levels may exist in kl/kl mice despite decreased insulin production, insulin tolerance tests (ITTs) were performed. The glucose decline following insulin injection was more severe in kl/kl mice versus wild-type mice, suggesting that insulin sensitivity was higher in kl/kl mice versus wild-type mice. In kl/kl mice, an augmented expression of GLUT4 in skeletal muscle was demonstrated by both Northern blot analysis and Western blot analysis. Thus, we conclude that insulin production is decreased and insulin sensitivity is increased in the klotho mouse, a novel animal model for human aging.

Adrenocorticotropic Hormone↗
PubMed2000

Preferential down-regulation of phospholipase C-beta in Ewing's sarcoma cells transfected with antisense EWS-Fli-1.

EWS-Fli-1, a fusion gene found in Ewing's sarcoma and primitive neuro-ectodermal tumour (PNET), encodes a transcriptional activator and promotes cellular transformation. We have made stable Ewing's sarcoma cells expressing antisense EWS-Fli-1 transcripts by transfecting the antisense EWS-Fli-1 expression plasmid. These cells showed partial loss of endogenous EWS-Fli-1 proteins and suppression of the cell growth. To elucidate the molecular mechanisms underlying the growth inhibition, we examined the changes of signal transducing proteins by immunoblot analysis in Ewing's sarcoma cells stably expressing antisense EWS-Fli-1 transcripts. Western blotting of the cell proteins revealed that expressions of phospholipase Cbeta2 and beta3 (PLCbeta2, PLCbeta3), and also protein kinase C alpha and beta (PKCalpha, beta) were significantly reduced by transfecting with antisense EWS-Fli-1. The inositol phosphates production by bradykinin (BK), but not platelet-derived growth factor (PDGF), was suppressed in these cells. These results suggest that the PLCbeta2 and PLCbeta3 may play a role in tumour proliferation in Ewing's sarcoma cells.

DNA, Antisense↗
PubMed2000

Lack of association between TTV viral load and aminotransferase levels in patients with hepatitis C or non-B-C.

TT virus (TTV) is a newly identified un-enveloped single-stranded DNA virus. Although TTV was initially thought to be a new hepatitis virus, it is still unclear whether it causes hepatitis. To clarify the natural history and pathogenesis of TTV infection, serial serum samples from patients with chronic hepatitis were analysed. TTV DNA was quantified by real-time detection polymerase chain reaction assay (RTD-PCR), which was adapted for TTV. Five patients with chronic hepatitis, 4 with hepatitis C and 1 with non-B-C, were studied. The study period ranged from 9 to 50 months. In 3 patients there were frequent increases in TTV DNA titres, but no concomitant elevation of the aminotransferase (ALT) levels. In 2 patients who were treated with interferon, the changes in TTV titres were not synchronized with those of the ALT levels. Thus, in cases of chronic hepatitis, no correlation was observed between the serum TTV DNA titres and the ALT levels.

Adult↗
PubMed2000

Long-term prospective study on the natural history of Wolff-Parkinson-White syndrome detected during a heart screening program at school.

UNLABELLED: In the period 1985 to 1993, a total of 802 school-aged children (284 first-graders and 518 seventh-graders) were referred to our hospital for further evaluation of electrocardiographic abnormalities. Among them, 57 (male 24 and female 33) children were confirmed as having Wolff-Parkinson-White (WPW) syndrome based on the findings of 12-lead surface electrocardiograms (ECG). According to Lindsay's criteria, the locations of the accessory pathways were as follows: Left-lateral in 10 (18%), left-posterior in 2 (4%), right-free-wall in 28 (49%), anterior-septum in 13 (23%) and posterior-septum in 3 (5%). One 12-y-old girl had multiple accessory pathways. Six patients had associated diseases: Ebstein's anomaly in 4, epilepsy in 1 and mental retardation with scoliosis in 1. Follow-up periods ranged from 2.0 to 13.0 y (mean +/- SD: 8.0 +/- 3.3 y) for 23 first-graders with WPW syndrome, and from 2.0 to 13.0y (mean +/- SD: 7.3 +/- 4.2y) for 34 seventh-graders, respectively. Initially, 5 children had at least one episode of supraventricular tachycardia (SVT) by history and 6 children developed SVT during the follow-up. One girl with multiple accessory pathways and recurrent SVT required long-term drug therapy. CONCLUSIONS: The outcome of children with WPW syndrome detected by a heart screening program at school was favorable. Our 8 y follow-up of 57 children with WPW syndrome will serve as additional information concerning the indication of radio-frequency catheter ablation therapy for WPW syndrome in children.

Adolescent↗
PubMed2000

Virolysis and in vitro neutralization of HIV-1 by humanized monoclonal antibody hNM-01.

Antibody humanization by transplanting the complimentarity determining region (CDR) to a human framework aims to reduce the response of the human immune system against a foreign molecule during passive immunization. We transferred the CDR from the murine monoclonal antibody (MAb) NM-01 to a human IgG frame. The humanized NM-01 (hNM-01) recognizes the same epitope on Human Immunodeficiency Virus type 1 (HIV-1) envelope as its murine progenitor, but with greater efficiency, and shows enhanced neutralization of HIV-1. We have shown that this increase in reactivity may be attributed to residue 4 of the humanized kappa chain, where the presence of a methionine residue rather than the murine leucine appears to promote a more advantageous conformation of the antigen-binding site, perhaps via packing interactions with the V(kappa) CDR1. The capacity of humanized NM-01 to neutralize direct clinical isolates was also examined with the expectation that hNM-01 will prove suitable for development as a therapeutic agent. This reshaped antibody reacted with several clinical isolates of HIV-1 tested. Moreover, we proved the ability of this antibody of its activation of complement by flow cytometry and electron microscopy analysis. Although hNM-01 alone was capable of neutralizing HIV-1, the presence of complement enhanced neutralization. The enhancement of complement activation was also observed in hNM-01 than murine progenitor. This finding supports a potential role for antibody-dependent complement-mediated virolysis and more effective neutralization in HIV-1 therapy.

Amino Acid Sequence↗
PubMed2000

Altered expression of amyloid precursors proteins after traumatic brain injury in rats: in situ hybridization and immunohistochemical study.

The expression of alternatively spliced mRNAs for amyloid precursor protein (APP) isoforms and their translation products were examined in the rat cerebral cortex 1, 3, 6, and 12 h and 1, 3, and 7 days (n = 4-5 in each group) after fluid-percussion brain injury. In situ hybridization studies demonstrated that the expression of APP695 mRNA decreased in and around the damaged area of the cerebral cortex exposed to fluid-percussion injury 1 h after the insult. On the other hand, APP751/770 mRNAs were increased in the regions surrounding the damaged cortical areas 1 day after the injury. An increase of immunoreactive APP was detected in the regions around the damaged cortical areas 3 h after traumatic injury and maintained for the following 3 days. The APP immunoreactivity in the damaged cortices declined to the level of sham-operated animals by post-experimental day 7. Using an anti-amyloid beta (Abeta) protein (17-24) antibody, no deposits of immunoreactive Abeta (17-24) were observed in any of the samples examined in these experiments. These results suggest that the induction of Kunitz-type protease inhibitor (KPI) domain-containing APP mRNAs and the increased accumulation of APP are involved in the physiological and neuropathological responses of brains under various neurodegenerative conditions, including head trauma.

Alternative Splicing↗
PubMed2000

Exit block of focal repetitive activity in the superior vena cava masquerading as a high right atrial tachycardia.

An unusual case of atrial tachycardia (AT) originating from the superior vena cava (SVC) is reported. A 34-year-old man without structural heart disease underwent catheter ablation for drug-resistant AT. During the tachycardia, low-amplitude spiky electrograms with a cycle length of 120 to 175 msec were recorded in the SVC and exhibited 2:1 exit block to the atria, masquerading as the atrial activation observed with high right AT. These spiky electrograms also were observed during sinus rhythm, but they appeared immediately after the local atrial electrograms. The spikes were traced to a point 3 cm above the junction of the right atrium. Radiofrequency ablation at the site of the earliest appearance of the spike in the SVC successfully eliminated the tachycardia. During the following 15 months, no clinically significant atrial arrhythmias, including atrial fibrillation, occurred. This report indicates that careful mapping, including inside the SVC, will be a requisite in patients with high right atrial tachyarrhythmias.

Adult↗
PubMed2000

Cytokine expression and production by purified Helicobacter pylori urease in human gastric epithelial cells.

Cytokines have been proposed to play an important role in Helicobacter pylori-associated gastroduodenal diseases, but the exact mechanism of the cytokine induction remains unclear. H. pylori urease, a major component of the soluble proteins extracted from bacterial cells, is considered to be one of the virulence factors for the inflammation in the gastric mucosa that is produced in H. pylori infection. However, the response of human gastric epithelial cells to the stimulation of urease has not been investigated. In the present study, we used human gastric epithelial cells in a primary culture system and examined whether H. pylori urease stimulates the gastric epithelial cells to induce proinflammatory cytokines by reverse transcription-PCR and enzyme-linked immunosorbent assay. First, by using peripheral blood mononuclear cells (PBMC) and a gastric cancer cell line (MKN-45 cells), we confirmed the ability of purified H. pylori urease to induce the production of proinflammatory cytokines. Furthermore, we demonstrated that the human gastric epithelial cells produced interleukin-6 (IL-6) and tumor necrosis factor alpha, but not IL-8, following stimulation with purified urease. The patterns of cytokine induction differed among human PBMC, MKN-45 cells, and human gastric epithelial cells. These results suggest that the human gastric epithelial cells contribute to the induction of proinflammatory cytokines by the stimulation of H. pylori urease, indicating that the epithelial cells were involved in the mucosal inflammation that accompanied H. pylori infection.

Adult↗
PubMed2000

Development of a TT virus DNA quantification system using real-time detection PCR.

Although TT virus (TTV) was isolated from a cryptogenic posttransfusion hepatitis patient, its pathogenic role remains unclear. It has been reported that the majority of the healthy population is infected with TTV. To elucidate the differences between TTV infection in patients with liver diseases and TTV infection in the healthy population, a quantification system was developed. TTV DNA was quantified by a real-time detection PCR (RTD-PCR) assay on an ABI Prism 7700 sequence detector. With this system, TTV DNA was quantified in 78 hepatitis C virus (HCV)-infected patients (63 with elevated serum alanine aminotransferase [ALT] levels and 15 with normal ALT levels) and in 70 voluntary blood donors (BDs). The quantification range was 2.08 to 7.35 log copies/ml. The intra-assay and interassay coefficients of variation were 0.37 to 6.33% and 0.60 to 7.07%, respectively. The mean serum TTV DNA levels in the HCV-infected patients with both elevated and normal ALT levels and BDs were 3.69 +/- 0.89, 3.45 +/- 0.76, and 3.45 +/- 0.67 log copies/ml, respectively. Comparison of the serum TTV DNA levels among the HCV-infected patients revealed that they were not related to the serum ALT and HCV core protein levels or to the histopathological score on liver biopsy. This study showed that (i) the RTD-PCR assay for the detection of TTV was accurate and had a high degree of sensitivity, (ii) the mean serum TTV DNA level was similar among HCV-infected patients, irrespective of their ALT level, and also among BDs, and (iii) a high serum TTV DNA level does not affect the serum ALT and HCV levels or liver damage in HCV-infected patients.

Blood Donors↗
PubMed2000

RT-PCR suggests human skeletal muscle origin of alveolar soft-part sarcoma.

In 1952, Christopherson et al. proposed that alveolar soft-part sarcoma (ASPS) was a distinct entity with unique clinical and pathological features. Since their report, its histogenesis has not been determined. In order to clarify the histogenesis of ASPS, a study using reverse transcription polymerase chain reaction using cDNAs from MyoD1 and myogenin, and the actin filament from human-skeletal-muscle-related mRNAs has been performed in 5 cases of ASPS. The expression of MyoD1 and myogenin was determined in 5 and 2 cases of the 5 cases, respectively. Moreover, expression of the many mRNAs from the actin filament of skeletal muscle was also found in ASPS. According to these findings, it is now postulated that ASPS is of skeletal muscle origin.

Actins↗
PubMed2000

Meloxicam inhibits prostaglandin E(2) generation via cyclooxygenase 2 in the inflammatory site but not that via cyclooxygenase 1 in the stomach.

We studied the effects of meloxicam on prostanoid levels, both in the inflammatory site in rat carrageenin-induced pleurisy and in the rat stomach injected with 1 mol/l NaCl solution, to clarify the relationship between its low gastric toxicity and its relative cyclooxygenase (COX) 2 selectivity. NS-398 (3 mg/kg), a highly selective COX-2 inhibitor, and meloxicam (3 mg/kg) exhibited anti-inflammatory effects in the pleurisy model. Prostaglandin (PG) E(2) thromboxane (TX) B(2) and 6-keto-PGF(1alpha) were detectable in the inflammatory site. Anti-inflammatory doses of NS-398 and meloxicam each suppressed the intrapleural PGE(2) level at 5 h as potently as piroxicam (3 mg/kg) as aspirin (100 mg/kg), both of which are nonselective COX inhibitors. NS-398 was much less potent than the other three in suppressing the levels of TXB(2) and 6-keto-PGF(1alpha). These results suggest that PGE(2) may be produced mainly via COX-2 in this model and that meloxicam may inhibit COX-2 in the inflammatory site. Piroxicam completely inhibited the increase in gastric PGE(2) induced by administering 1 mol/l NaCl solution into the rat stomach. Nimesulide (3 mg/kg), another selective COX-2 inhibitor, however, never affected this increase, suggesting that the gastric PGE(2) may be produced via COX-1. The anti-inflammatory dose of meloxicam caused statistically nonsignificant suppression of the PGE(2) level, by approximately 50%. These results suggest that the potent anti-inflammatory effect of meloxicam, accompanied with low gastric toxicity, may be related to its relative selectivity for COX-2 over COX-1.

6-Ketoprostaglandin F1 alpha↗
PubMed2000

Benidipine inhibits apoptosis during ischaemic acute renal failure in rats.

We have investigated the effects of benidipine (hydrochloride), a calcium antagonist, against ischaemic acute renal failure in rats. Using histological examination, we studied whether the inhibition of apoptosis was associated with the protective effects of benidipine on the ischaemic renal injury. Acute renal failure was induced by the unilateral clamping of the left renal artery for 60 min, followed by reperfusion and contralateral nephrectomy. Drugs were given intravenously 5 min before the unilateral clamping. Prophylactic administrations of benidipine (10 microg kg(-1), i.v.) significantly ameliorated the development of renal failure as estimated by the measurements of serum creatinine and blood urea nitrogen 24 h after the reperfusion. Amlodipine (besilate, 100 and 300 microg kg(-1), i.v.) tended to attenuate renal dysfunction. Lisinopril (300 and 1000 microg kg(-1), i.v.), an angiotensin converting enzyme inhibitor, was ineffective in this acute renal failure model. Histological examination using the terminal transferase-mediated dUTP-biotin nick end-labelling (TUNEL) method to detect apoptotic cells revealed that the TUNEL-positive tubular epithelium was prominent in the renal cortex 24 h after the reperfusion. The TUNEL-positive cells were significantly reduced by pretreatment with benidipine. The results demonstrate that benidipine can ameliorate the ischaemic acute renal failure in rats and suggest that the renoprotective effect of benidipine was at least partly attributable to the reduction of apoptosis in tubular epithelial cells.

Acute Kidney Injury↗
PubMed2000

Antioxidant effects of calcium antagonists in rat brain homogenates.

We studied the antioxidant activities of calcium antagonists against autoxidation in rat brain homogenates. The homogenates were incubated for 30 min at 37 degrees C with or without a calcium antagonist and subsequently assayed for lipid peroxide content. Percent inhibition of the lipid peroxidation was used as an index of the antioxidant effect. Dihydropyridine calcium antagonists exhibited concentration-dependent (3-300 micromol/l) inhibitory effects against lipid peroxidation. The relative order of antioxidant potency and associated IC50 values (micromol/l) of the calcium antagonists for inhibition of the lipid peroxidation were as follows: nifedipine (51.5)>barnidipine (58.6)>benidipine (71.2)>nicardipine (129.3)>amlodipine (135.5)>nilvadipine (167.3)>nitrendipine (252.1)>> diltiazem (>300)=verapamil (>300). These results suggest that some dihydropyridine calcium antagonists show antioxidant properties. The antioxidant effects of the calcium antagonists may contribute to their pharmacological actions.

Animals↗
PubMed2000

Effect of the selective adenosine A1-receptor antagonist KW-3902 on lipopolysaccharide-induced reductions in urine volume and renal blood flow in anesthetized dogs.

We investigated the effects of KW-3902 (8-noradamantan-3-yl-1,3-dipropylxanthine), a potent and selective adenosine A1-receptor antagonist, on lipopolysaccharide (LPS)-induced reduction of urine volume (UV) in anesthetized dogs, in comparison with those of furosemide. LPS was intravenously administered at a dose of 0.5 mg/kg; and the heart rate (HR), systemic blood pressure (BP), renal blood flow (RBF) and UV were measured every 15 min for 4 h. Administration of LPS continuously decreased HR, BP, RBF and UV. KW-3902, furosemide or their corresponding vehicle was given as a bolus injection 5 min after the LPS injection. Treatment with KW-3902 (1 mg/kg, i.v.) ameliorated the LPS-induced decline of UV and RBF. Furosemide (3.2 mg/kg, i.v.) tended to ameliorate the LPS-induced decline of UV but not RBF, the duration of the effect being shorter than that of KW-3902. These results suggest that KW-3902 can ameliorate the oliguria and the decrease in RBF during the early phase of LPS-induced shock. Endogenous adenosine may be involved in the endotoxin-induced oliguria via the adenosine A1-receptor.

Animals↗