Biomedical subjects

Takashi Kondo

Publications and source records attributed to Takashi Kondo.

At least 37 records · Page 2Linked to original sources

PubMed2006

Isolation and genetic analysis of Japanese encephalitis virus from a diseased horse in Japan.

Japanese encephalitis (JE) developed in an unvaccinated half-bred horse kept in Tottori Prefecture, Japan. The animal showed ataxia with pyrexia and low appetite, and ultimately died. A viral strain was isolated from the cerebrum of the horse and was identified as JE virus (JEV) by RT-PCR using JEV specific primers. The isolated JEV was classified into genotype I by nucleotide sequence analysis of the viral envelope gene. We believe that this is the first report of the genotype I strain being isolated from a horse.

Animals↗

PubMed2006

In vitro efficacies of oseltamivir carboxylate and zanamivir against equine influenza A viruses.

To investigate the possibilities of two NA inhibitors [oseltamivir carboxylate (OC) and zanamivir (ZA)] as the clinical agents for equine influenza A virus (EIV) infection, we examined the efficacies of these inhibitors against twelve EIVs in vitro. OC and ZA inhibited NA activities of all EIVs with 50% inhibitory concentrations with ranging from 0.017 to 0.130 and from 0.010 to 0.074 microM, respectively. OC and ZA inhibited plaque-forming of all EIVs in MDCK cells with 50% effective concentrations with ranging from 0.015 to 0.097 and from 0.016 to 0.089 microM, respectively, except for one strain (13.328 microM and 6.729 microM). These results suggest that these inhibitors are effective against most EIVs and might be useful for treatment of EI in horses.

Acetamides↗

PubMed2006

Efficacy of oseltamivir phosphate to horses inoculated with equine influenza A virus.

We investigated the efficacy of the oral administration of oseltamivir phosphate (OP) in horses experimentally infected with equine influenza A virus (H3N8). Nine horses were divided into three horses each of control, treatment and prophylaxis groups. An administration protocol for the treatment group (2 mg/kg of body weight, twice a day for five days) was started immediately after the onset of pyrexia (above 38.9 degrees C). An administration protocol for the prophylaxis group (2 mg/kg of body weight, once a day for five days) was started on a day before viral inoculation. In the treatment group, periods of virus excretion (mean days +/- standard deviation, 2.3 +/- 0.6) and pyrexia (2.0 +/- 0.0) were apparently shorter than those of the control group (6.0 +/- 0.0 and 8.0 +/- 1.0, respectively). In the prophylaxis group, although virus excretion and pyrexia were not prevented, the periods of virus excretion (5.0 +/- 0.0) and pyrexia (4.7 +/- 1.5) were shorter than those of the control group. Moreover, in the treatment and prophylaxis groups, bacterial counts of Streptococcus equi subsp. zooepidemicus known as the common pathogen of secondary bacterial pneumonia in bronchoalveolar lavage fluids collected seven days after inoculation were significantly fewer than that of the control group. The results indicated that the oral administration of OP to horses affected with equine influenza would contribute to reduce the magnitude of virus excretion, pyrexia and consequent secondary bacterial pneumonia.

Acetamides↗

PubMed2006

Overexpression of heat shock protein 70 restores the structural stability and functional defects of temperature-sensitive mutant of large T antigen at nonpermissive temperature.

The effects of heat shock protein 70 (Hsp70), a molecular chaperone, on the degradation and functional alterations of a mutant large T antigen induced by a nonpermissive temperature were examined. In this study, mouse tracheal epithelial TM02-3 cells harboring temperature-sensitive simian virus 40 large T antigen and stable TM02-3 cells overexpressing human Hsp70 and/or Hsp40 were used. Although the temperature shift from 33 degrees C (permissive temperature) to 39 degrees C (nonpermissive temperature) induced increases in the endogenous chaperones including Hsp70 and Hsp40, degradation of the T antigen, activation of the p53-p21(waf1) pathway, and an arrest of cell growth were observed in the mock cells. In contrast, these changes induced by the temperature shift were partially but significantly prevented in stable cells overexpressing human Hsp70 and/or Hsp40. A combination of Hsp70 and Hsp40 was the most effective, suggesting that Hsp40 may cooperate with Hsp70. Moreover, immunocytochemical observation indicated that human Hsp70 was expressed in the cytoplasm at 33 degrees C, but it colocalized with T antigen in the nucleus at 39 degrees C. These results suggest that overexpressed Hsp70 translocates from the cytoplasm to nucleus, and significantly restores the structural stability and functional defects of mutant large T antigen in the cells.

Animals↗

PubMed2006

Impact of lung preservation solutions, Euro-Collins vs. low-potassium dextran, on early graft function: a review of five clinical studies.

Currently, intracellular fluid type solutions that are prepared by modification of Euro-Collins solution (EC) have been the most commonly used by clinical lung transplant programs, which have been associated with a high rate of reperfusion injury. On the basis of the wealth of experimental data demonstrating the benefit of extracellular fluid type solutions over EC, one of the extracellular solutions, low-potassium dextran solution (LPD), became commercially available and has recently been applied to clinical settings. To date there have been 5 clinical studies comparing the effect of EC with LPD on early lung graft function. This article reviewed these 5 reports to determine whether the beneficial effects of LPD, as observed in experimental settings, can also be identified in clinical lung preservation. Four studies were retrospective reviews and one was a prospective non-randomized study. Of these 5 studies, 3 studies demonstrated significantly improved recipient oxygenation in the LPD group compared with the EC group in the early post-operative period. In addition, a significantly shorter duration on mechanical ventilation in the LPD group was shown in 2 studies, and improved reperfusion scores or pulmonary compliance was shown in one study each. Four of 5 studies concluded that graft preservation with LPD leads to superior early graft function after lung transplantation. The impact of LPD on prolonged lung preservation and also on long term results of graft function will be a subject of future investigation.

APACHE↗

PubMed2006

[Indication and procedure of video-assisted thoracoscopic surgery to thymic disease].

We retrospective reviewed minimally invasive video-assisted thoracoscopic surgery (VATS) to thymic diseases. These procedures were performed using intercostal and infrasternal approach with a sternum-elevator. Indications of this method are benign thymic lesions [mature teratoma, thymic cyst and myasthenia gravis (MG)] and small thymoma (non-invasive Masaoka stage I-II, less than 5 cm in diameter and nontouching to the left brachiocephalic vein). Fifty patients underwent VATS for 13 hemithymectomies (7 thymomas, 5 mature teratomas and 1 thymic cyst) and 37 extended thymectomies (25 nonthymomatous MGs and 12 thymomatous MGs). Conversion to sternotomy was required in 3 cases of nonthymomatous MG because of bleeding from thymic vein in 1 case and pleural adhesion in 2 cases. Four cases of thymomatous MG were successfully treated with partial lung resection and/or small pericardial resection by VATS. New bipolar vessel sealing system (LigaSure V) is safer and more useful than metal clip and ultrasonic coagulator in VATS for thymic vein sealing, extraction of upper poles of thymus and incision of mediastinal pleura near phrenic nerve. VATS thymectomy should be useful from the standpoint of less invasive, less pain, rapid recovery, and good cosmetic results.

Female↗

PubMed2005

An echo-contrast agent, Levovist, lowers the ultrasound intensity required to induce apoptosis of human leukemia cells.

To verify the effect of echo-contrast agent (ECA) on apoptosis induced by ultrasound, leukemia cell lines (Jurkat, Molt-4 and U937) were sonicated at intensities previously shown to induce optimal apoptosis with or without Levovist, an ECA. The results showed that loss of viability and apoptosis can be induced in all three cell lines, apoptosis highest with Molt-4, based on viability and DNA fragmentation assay. Such finding was supported by corresponding increase of cells with low mitochondrial membrane potential, high superoxide production, increased intracellular calcium concentration, and phosphorylation of histone H2AX after sonication. Optimal ultrasound condition was 0.3W/cm(2), 1MHz, 10% duty factor pulsed at 100Hz; but in the presence of Levovist, an apparent shift of cell killing induction was observed at 0.2W/cm(2). While these results further confirmed previous findings on ultrasound-induced apoptosis, they also suggest that use of an enhancing factor, such as addition of ECA, may be useful in cancer therapy when a much lower intensity is desired.

Apoptosis↗

PubMed2005

Comparison between sonodynamic effect and photodynamic effect with photosensitizers on free radical formation and cell killing.

Although enhancement of ultrasound-induced cell killing by photodynamic reagents has been shown, the sonochemical mechanism in detail is still not clear. Here, comparison between sonodynamic effect and photodynamic effect with photosensitizers at a concentration of 10 microM on free radical formation and cell killing was made. When electron paramagnetic-resonance spectroscopy (EPR) was used to detect 2,2,6,6-tetramethyl-4-piperidone-N-oxyl (TAN) after photo-irradiation or sonication with 2,2,6,6-tetramethyl-4-piperidone (TMPD), the order of TAN formation in the photo-irradiated samples was as follows: rhodamine 6G (R6) > sulforhodamine B (SR) > hematoporphyrin (Hp) > rhodamine 123 (R123) > rose bengal (RB)>erythrosine B (Er) = 0; although there was time-dependent TAN formation when the samples were sonicated, no significant difference among these agents were observed. All these agents suppressed ultrasound-induced OH radical formation detected by EPR-spin trapping. Sensitizer-derived free radicals were markedly observed in SR, RB and Er, while trace level of radicals derived from R6 and R123 were observed. Enhancement of ultrasound-induced decrease of survival in human lymphoma U937 cells was observed at 1.5 W/cm(2) (less than inertial cavitation threshold) for R6, R123, SR and Er, and at 2.3 W/cm(2) for R6, R123, Er, RB and SR. On the other hand, photo-induced decrease of survival was observed for R6, Hp and RB at the same concentration (10 microM). These comparative results suggest that (1) (1)O(2) is not involved in the enhancement of ultrasound-induced loss of cell survival, (2) OH radicals and sensitizer-derived free radicals do not take part in the enhancement, and (3) the mechanism is mainly due to certain mechanical stress such as augmentation of physical disruption of cellular membrane by sensitizers in the close vicinity of cells and/or cavitation bubbles.

Electron Spin Resonance Spectroscopy↗

PubMed2005

Mechanism of cell death induction by nitroxide and hyperthermia.

Heat stress and nitroxides induce reactive oxygen species (ROS) and proapoptotic effects. The underlying mechanisms remain largely elusive. Here we report that Tempo (2,2,6,6-tetramethylpiperidine-N-oxyl) is a potent thermosensitizer for promoting cell death in human leukemia U937 cells. Treatment with Tempo (10 mM, 37 degrees C/30 min) and hyperthermia (44 degrees C/30 min) induced 30 and 70-80% apoptosis, respectively, through Bax-mediated cytochrome c release and DEVDase activation. The Tempo/heat combination also caused Bax-mediated cytochrome c release, but switched heat-induced apoptosis to the particular pyknotic cell death, resulting in the irreparable inhibition of proliferation. Tempo and heat stress, but not the combination, caused an early transient elevation of H2O2/O2*- and a late induction of only O2*-, respectively. Mitochondrial Ca2+ overloads were indistinguishable after any treatment. Heat stress induced the pan-caspase inhibitor zVAD-fmk-suppressible low-Deltapsi (mitochondrial membrane potential) in 75% of cells as a result of DEVDase activation. In contrast, Tempo yielded low-Deltapsi by deprivation of the mitochondrial H+ gradient. The combined treatment induced 97% zVAD-resistant low-Deltapsi cells through irreversible mitochondrial dysfunction. Together, thus, Tempo or heat stress induced Bax-mediated mitochondrial apoptosis with the possible help of ROS or mitochondrial Ca2+, and Tempo when combined with hyperthermia acts a sensitizer by inducing irreparable pyknotic cell death through irreversible mitochondrial dysfunction.

Apoptosis↗

PubMed2005

Expression of heme oxygenase-1 due to intracellular reactive oxygen species induced by ultrasound.

The present study was undertaken to elucidate the mechanism by which ultrasound induces the expression of heme oxygenase-1 (HO-1). When human lymphoma U937 cells were exposed to a 1 MHz continuous wave for 1 min, HO-1 expression examined by real-time quantitative polymerase chain reaction and immunoblotting was observed at intensities above the cavitational threshold. No induction of HO-1 expression was observed in the cells exposed for 1 min to 42 degrees C, a temperature higher than that during sonication. When a potent antioxidant, N-acetyl-l-cysteine, was added to the culture medium before or after sonication, the induction was attenuated, indicating that reactive oxygen species (ROS) are involved. However, the addition of catalase did not affect the induction, and no HO-1 was observed on the addition of pre-sonicated medium, suggesting that hydrogen peroxide due to the recombination of hydroxyl radicals generated extracellularly was not involved. The addition of free radical scavengers, glutathion-monoethyl ester, dimethyl sulfoxide and D(-)-mannitol, suppressed the induction. A decrease in mitochondrial membrane potential and the generation of superoxide were also observed in the sonicated cells, suggesting that mitochondria were the source of intracellularly generated ROS. These results indicate that superoxide secondarily generated from damaged mitochondria, not hydroxyl radicals generated in medium directly by sonication, give rise to intracellular oxidative stress inducing HO-1 expression.

Acetylcysteine↗

PubMed2005

Altered expression of chemokine receptor CXCR5 on T cells of myasthenia gravis patients.

Myasthenia gravis (MG) is characterized by the T cell-dependent production of anti-acetylcholine receptor (AChR) antibodies. The chemokine receptor CXCR5 regulates lymphocyte migration and is expressed on a subset of CD4+ T cells named follicular helper T cells (T(FH)), the key modulators of antibody production by B cells. We studied the frequency of CXCR5-positive lymphocytes in the peripheral blood of MG patients before and after therapy (thymectomy plus glucocorticoid). Before therapy, the MG patients showed a significantly higher frequency of CXCR5+ CD4+ T cells in the peripheral blood compared with the control group, while no significant difference in the percentages of CXCR5+ CD4+ T cells was observed between the patients of the hyperplasia group and those of the thymoma group. The CXCR5+ CD4+ T cell frequency correlated with the disease severity. The CXCR5+ CD4+ T cell frequency of MG patients positive for other autoantibodies together with anti-AChR antibodies was significantly higher than in those having only anti-AChR antibodies. After therapy, the CXCR5+ CD4+ T cell percentage decreased gradually to the control level with a significant inverse correlation between the CXCR5+ CD4+ T cell frequency and duration after the initiation of MG therapy. The CXCR5+ CD4+ T cell populations in the hyperplastic thymuses and thymomas were not significantly different from those in the control thymuses. These results suggest that CXCR5+ CD4+ T cells play an important role in the disease activity of MG and that some MG patients have a systemic abnormality in T cell-dependent antibody production.

Adult↗

PubMed2005

Ultrasound liberates nitric oxide (NO) from the caged NO compound N,N'-bis(carboxymethyl)-N,N'-dinitroso-p-phenylenediamine sodium salt.

To determine whether nitric oxide (NO) can be released from a cage compound N,N'-bis(carboxymethyl)-N,N'-dinitroso-p-phenylenediamine sodium salt (BNN 5 Na), we sonicated different concentrations of BNN 5 Na solutions containing an NO spin trap, (MGD)2Fe2+, and then measured (MGD)2Fe2+-NO signal using electron paramagnetic resonance (EPR). We also investigated the role of cavitation by saturating the solutions with Ar, He or Xe gases before sonication. The result showed that ultrasound can liberate NO from caged NO compound at rates highest with Xe and lowest with He. These results suggest that high-temperature due to cavitations induced by ultrasound are capable of releasing NO from caged NO compounds. This finding also opens up to a new possibility for the use of ultrasound in a controlled release of active compound (e.g. drug) from its caged form for therapeutic purposes.

Argon↗

PubMed2005

Estrogen inhibits cell proliferation through in situ production in human thymoma.

PURPOSE: We showed previously estrogen receptor (ER) alpha as an independent prognostic marker in human thymoma. Estrogen sulfotransferase (EST), steroid sulfatase (STS), 17beta-hydroxysteroid dehydrogenase (17beta-HSD), and aromatase are considered to play important roles in hormone metabolism of estrogen-dependent tumors. EXPERIMENTAL DESIGN: We examined estrogen production using primary cultures of human thymoma epithelial cells (TEC), intratumoral estradiol (E(2)) concentrations, and status of these enzymes above using immunohistochemistry or semiquantitative reverse transcription-PCR. We then correlated these findings with clinicopathologic variables and/or clinical outcome in 132 patients. RESULTS: E(2) inhibited cell proliferation via ERalpha in TEC, which synthesized estrone and E(2). Intratumoral E(2) concentrations were inversely correlated with EST, positively correlated with STS or 17beta-HSD type 1, and significantly higher in lower-grade or early-stage thymoma. EST status was positively correlated with tumor size, clinical stage, histologic differentiation, and Ki-67 labeling index and significantly associated with adverse clinical outcome and turned out to be a potent independent prognostic factor. STS and/or 17beta-HSD type 1 status was inversely correlated with Ki-67 labeling index and associated with lower histologic grade or early clinical stages. CONCLUSIONS: E(2) inhibits proliferation of TEC through ERalpha, which suggests that E(2) may be effective in treatment of thymoma, especially inoperable tumor, possibly through suppressing its cell proliferation activity. EST status is a potent prognostic factor in thymoma through inactivating estrogens. In situ estrogen synthesis through intracrine mechanism therefore may play important roles in tumorigenesis and/or development of thymoma through regulation of cell proliferation in an intracrine manner.

17-Hydroxysteroid Dehydrogenases↗

PubMed2005

Analysis of yearly changes in levels of antibodies to Japanese encephalitis virus nonstructural 1 protein in racehorses in central Japan shows high levels of natural virus activity still exist.

Recent reductions in numbers of human and equine Japanese encephalitis (JE) cases in Japan have seen calls to end JE vaccination. Here, we analyzed yearly variations of natural JE virus activity, using sera collected serially in 1998-2003 from racehorses residing in Ibaraki and Shiga prefectures, both located in central Japan. A total of 208 sera from 24 individuals in Ibaraki and 259 from 27 in Shiga were examined for antibodies to JE virus nonstructural 1 (NS1) protein, a marker of natural infection. The natural infection rate in epizootic seasons, which was determined by a significant increase in NS1 antibody level, was 4.2-26.7% in Ibaraki and 0-41.7% in Shiga, indicating that high levels of JE virus activity still existed in central Japan.

Animals↗

PubMed2005

Progesterone receptor in non-small cell lung cancer--a potent prognostic factor and possible target for endocrine therapy.

A possible involvement of gender-dependent factors has been postulated in development of human non-small-cell lung cancers (NSCLC), but its details remain unclear. In this study, we examined biological significance of progesterone receptor in NSCLCs. Progesterone receptor immunoreactivity was detected in 106 of 228 NSCLCs (46.5%). Progesterone receptor-positive NSCLC was frequently detected in female and adenocarcinoma, and was inversely associated with tumor-node-metastasis stage and histologic differentiation. Progesterone receptor status was also associated with better clinical outcome of the patients, and a multivariate analysis revealed progesterone receptor status as an independent prognostic factor. Progesterone-synthesizing enzymes were detected in NSCLCs, and tissue concentration of progesterone was higher in these cases (n = 42). Immunoblotting analyses showed the presence of progesterone receptor in three NSCLC cell lines (A549, LCSC#2, and 1-87), but not in RERF-LC-OK or PC3. Transcriptional activities of progesterone receptor were increased by progesterone in these three progesterone receptor-positive NSCLC cells by luciferase assays. Cell proliferation was inhibited by progesterone in these progesterone receptor-positive NSCLC cells in a dose-dependent manner, which was inhibited by progesterone receptor blocker. Proliferation of these tumor cells injected into nude mice was also dose-dependently inhibited by progesterone, with a concomitant increase of p21 and p27 and a decrease of cyclin A, cyclin E, and Ki67. Results of our present study suggested that progesterone receptor was a potent prognostic factor in NSCLCs and progesterone inhibited growth of progesterone receptor-positive NSCLC cells. Therefore, progesterone therapy may be clinically effective in suppressing development of progesterone receptor-positive NSCLC patients.

Adult↗

PubMed2005

Dynamic rearrangement of telomeres during spermatogenesis in mice.

Chromosomal structure within the nucleus influences various biological processes such as transcription and replication. Telomeres are located at the end of eukaryotic chromosomes and they can be a decisive factor for correct chromosomal positioning. To gain new insight into telomere dynamics, we examined telomere length and positional changes during spermatogenesis using improved fluorescence in situ hybridization (FISH) and in situ telomeric repeat amplification protocols (TRAP) on histological sections. FISH revealed telomere length and chromosome position within nuclei change dynamically. Telomere extension occurred during spermiogenesis. In situ TRAP analysis verified elevated telomerase activity in elongating spermatids. Together, these data show that elongated spermatids have longer telomeres than precursor spermatogenic cells. This observation indicates that telomere elongation in haploid cells occurs after meiosis and in the absence of genomic replication. Analyses of testes from telomerase null mice further support the significance of telomere dynamics during spermatogenesis and the existence of an alternative telomere extension pathway.

Animals↗

PubMed2005

Apoptosis induced by the sonomechanical effects of low intensity pulsed ultrasound in a human leukemia cell line.

To obtain an optimal condition for ultrasound (US)-induced apoptosis that could be useful for cancer therapy, we applied low intensity pulsed US to sonicate U937 cells in vitro. Cells were then incubated at different time intervals before measuring apoptosis. The apoptosis was assessed by DNA fragmentation and phosphatidylserine externalization. The pattern of the decrease in mitochondrial membrane potential was determined by flow cytometry. Optimal apoptosis (70.0+/-13.8%) with minimal lysis was attained with 1 MHz ultrasound 0.3 W/cm2, 10% duty factor at 100 Hz for 1 min) at 12 h after sonication. Lack of US-induced free radical detection and absence of Heme oxygenase-1, an intracellular oxidative stress marker, up-regulation in cells, suggest that sonomechanical, not sonochemical, effects are the main mechanism involved.

Apoptosis↗

PubMed2005

Genes involved in nonpermissive temperature-induced cell differentiation in Sertoli TTE3 cells bearing temperature-sensitive simian virus 40 large T-antigen.

Sertoli TTE3 cells, derived from transgenic mice bearing temperature-sensitive simian virus 40 large T (tsSV40LT)-antigen, proliferated continuously at a permissive temperature (33 degrees C) whereas inactivation of the large T-antigen by a nonpermissive temperature (39 degrees C) led to differentiation as judged by elevation of transferrin. To clarify the detailed mechanisms of differentiation, we investigated the time course of changes in gene expression using cDNA microarrays. Of the 865 genes analyzed, 14 genes showed increased levels of expression. Real-time quantitative PCR revealed that the mRNA levels of p21(waf1), milk fat globule membrane protein E8, heat-responsive protein 12, and selenoprotein P were markedly elevated. Moreover, the differentiated condition induced by the nonpermissive temperature significantly increased mRNA levels of these four genes in several cell lines from the transgenic mice bearing the oncogene. The present results regarding changes in gene expression will provide a basis for a further understanding of molecular mechanisms of differentiation in both Sertoli cells and cell lines transformed by tsSV40LT-antigen.

Animals↗