Biomedical subjects
Publications and source records attributed to S Tasaka.
Muon neutrino disappearance probability as a function of neutrino flight length L over neutrino energy E was studied. A dip in the L/E distribution was observed in the data, as predicted from the sinusoidal flavor transition probability of neutrino oscillation. The observed L/E distribution constrained nu(micro)<-->nu(tau) neutrino oscillation parameters; 1.9x10(-3) 0.90 at 90% confidence level.
A search for a nonzero neutrino magnetic moment has been conducted using 1496 live days of solar neutrino data from Super-Kamiokande-I. Specifically, we searched for distortions to the energy spectrum of recoil electrons arising from magnetic scattering due to a nonzero neutrino magnetic moment. In the absence of a clear signal, we found micro(nu)</=(3.6x10(-10))micro(B) at 90% C.L. by fitting to the Super-Kamiokande day-night spectra. The fitting took into account the effect of neutrino oscillation on the shapes of energy spectra. With additional information from other solar neutrino and KamLAND experiments constraining the oscillation region, a limit of micro(nu)</=(1.1x10(-10))micro(B) at 90% C.L. was obtained.
We present the results of a search for low energy nu(e) from the Sun using 1496 days of data from Super-Kamiokande-I. We observe no significant excess of events and set an upper limit for the conversion probability to nu(e) of the 8B solar neutrino. This conversion limit is 0.8% (90% C.L.) of the standard solar model's neutrino flux for total energy=8-20 MeV. We also set a flux limit for monochromatic nu(e) for E(nu(e))=10-17 MeV.
A search for the relic neutrinos from all past core-collapse supernovae was conducted using 1496 days of data from the Super-Kamiokande detector. This analysis looked for electron-type antineutrinos that had produced a positron with an energy greater than 18 MeV. In the absence of a signal, 90% C.L. upper limits on the total flux were set for several theoretical models; these limits ranged from 20 to 130 macro nu(e) cm(-2) s(-1). Additionally, an upper bound of 1.2 macro nu(e) cm(-2) s(-1) was set for the supernova relic neutrino flux in the energy region E(nu)>19.3 MeV.
Solar neutrino measurements from 1258 days of data from the Super-Kamiokande detector are presented. The measurements are based on recoil electrons in the energy range 5.0-20.0 MeV. The measured solar neutrino flux is 2.32+/-0.03(stat)+0.08-0.07(syst)x10(6) cm(-2) x s(-1), which is 45.1+/-0.5(stat)+1.6-1.4(syst)% of that predicted by the BP2000 SSM. The day vs night flux asymmetry (Phi(n)-Phi(d))/Phi(average) is 0.033+/-0.022(stat)+0.013-0.012(syst). The recoil electron energy spectrum is consistent with no spectral distortion. For the hep neutrino flux, we set a 90% C.L. upper limit of 40x10(3) cm(-2) x s(-1), which is 4.3 times the BP2000 SSM prediction.
We report the result of a search for neutrino oscillations using precise measurements of the recoil electron energy spectrum and zenith angle variations of the solar neutrino flux from 1258 days of neutrino-electron scattering data in Super-Kamiokande. The absence of significant zenith angle variation and spectrum distortion places strong constraints on neutrino mixing and mass difference in a flux-independent way. Using the Super-Kamiokande flux measurement in addition, two allowed regions at large mixing are found.
The structure activity relationships were studied on newly synthesized 1,4-dihydropyridine derivatives possessing a 1-pentyl group at the 4-position, and 3-pyridylpropylester was found to be one of the effective fragments for overcoming P-glycoprotein mediated multidrug-resistance (MDR) in cultured human cancer cells, in vitro. 3-Pyridylpropylester was also found to be one of the effective fragments for increasing the life span of P-glycoprotein overexpressing MDR P388 leukemia-bearing mice, in vivo. All compounds had weak calcium antagonistic activities, but there appeared no relationship between MDR reversing effect and calcium antagonistic activity.
The previously published atmospheric neutrino data did not distinguish whether muon neutrinos were oscillating into tau neutrinos or sterile neutrinos, as both hypotheses fit the data. Using data recorded in 1100 live days of the Super-Kamiokande detector, we use three complementary data samples to study the difference in zenith angle distribution due to neutral currents and matter effects. We find no evidence favoring sterile neutrinos, and reject the hypothesis at the 99% confidence level. On the other hand, we find that oscillation between muon and tau neutrinos suffices to explain all the results in hand.
Reexpansion of a collapsed lung induces increased microvascular permeability leading to reexpansion pulmonary edema (REPE). This study was designed to prove the hypothesis that local overproduction of interleukin-8 (IL-8) induces inflammatory cell accumulation which leads to the induction of REPE. Initially, we examined the detailed characteristics of a rabbit model of REPE in association with IL-8 production and its mRNA expression. The lung tissue to plasma ratio of radiolabeled albumin (T/P ratio), the lung wet to dry ratio, and bronchoalveolar lavage (BAL) neutrophil counts were significantly increased in the reexpanded lung. IL-8 concentrations and mRNA expression were significantly increased in the reexpanded lung homogenate. Immunohistochemically, alveolar macrophages (AMs) and epithelial cells in the reexpanded lung and AMs in the collapsed lung were positive for IL-8. Second, we examined the effect of pretreatment with a specific monoclonal anti-IL-8 antibody (Ab) or control IgG on the development of REPE. The T/P ratio and BAL neutrophil counts were conspicuously decreased by pretreatment with anti-IL-8 Ab, but not with control IgG. On a histopathological study, lung injury and leukocyte infiltration were attenuated by the pretreatment with anti-IL-8 Ab. In conclusion, IL-8 production is enhanced in the reexpanded lung, and contributes to the development of REPE. The pretreatment with anti-IL-8 antibody may be useful as a novel protective therapy for this disease.
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The clinical and immunoregulatory effects of long-term macrolide antibiotic therapy for patients with chronic lower respiratory tract infections (CLRTI) were investigated. Clinical parameters and neutrophil chemotactic mediators in the epithelial lining fluid (ELF) of CLRTI patients (n = 10) were examined before and after 3 months oral administration of roxithromycin (RXM). The in vitro effects of RXM were also examined on the release of these mediators from alveolar macrophages (AM) and neutrophils. Arterial oxygen tension (p<0.05), vital capacity (VC) (p<0.001), %VC (p<0.05) and forced expiratory volume in one second (p<0.01) were improved after RXM treatment, but airway bacteria were not eradicated. Among the mediators, the levels of interleukin (IL)-8, neutrophil elastase (NE) and leukotriene B4 (LTB4) were higher in ELF than in plasma of CLRTI patients and they decreased after RXM treatment (n = 7, p<0.05 for each). RXM concentrations were significantly increased in the bronchoalveolar lavage cells of the treated patients. In in vitro experiments, RXM showed inhibitory effects on IL-8 release from AM and neutrophils. In conclusion, interleukin-8, neutrophil elastase and leukotriene B4 contribute to the neutrophilic inflammation in the airways of chronic lower respiratory tract infection patients and the clinical effects of roxithromycin may, in part, be attributable to the suppression of excess release of the chemotactic mediators from inflammatory cells.
Newly synthesized 1,4-dihydropyridine derivatives possessing alkyl chains at the 4-position screened whether they could overcome P-glycoprotein-mediated multidrug resistance in cultured cancer cells and also leukemia-bearing animals. Of these derivatives, some could overcome drug resistance to doxorubicin and vincristine in multidrug resistant human cancer cell lines. Combined administration of vincristine and some of the derivatives significantly increased the life span of P-glycoprotein overexpressing multidrug-resistant P388 leukemia-bearing mice. The calcium antagonistic activities, an undesirable effects, were weaker than that of verapamil. These results suggested that the introduction of alkyl groups at the 4-position were effective for both overcoming multidrug resistance and reducing the calcium antagonistic activity.
A 55-year-old woman was admitted to our hospital with progressive dyspnea that had begun one month before. Chest rentogenogram revealed groundglass appearance and reticular shadows bilaterally. Pulmonary function tests showed both decreased vital capacity and diffusing capacity. Bronchoalveolar lavage fluid had a high lymphocyte fraction with a low CD4+/CD8+ ratio. Thoracoscopic lung biopsy revealed thick, fibro-edematous interstitium and diffuse infiltration of lymphocytes. We also observed an intra-alveolar exudate with infiltration of histiocytes and lymphocytes. The clinical features and pathological findings were consistent with subacute interstitial pneumonia, which was the entity proposed by Kawabata and colleagues. The patient developed acute respiratory failure four days after lung biopsy and died despite steroid pulse therapy. Although subacute interstitial pneumonia has been reported to respond to steroid therapy, and to have a good prognosis, we believe that subacute interstitial pneumonia could fatally worsen when associated with lung biopsy, infection, or some other stimulus.
A 60-year-old man was admitted to our hospital complaining of non-productive cough. He had worked in Africa and received a blood transfusion after a traffic accident in 1985. On admission, the patient had remarkable hypoxemia and a decreased CD4+ lymphocyte count. A serological test for human immuno-deficiency virus (HIV)-1 was positive. His chest radiographs showed diffuse reticular and linear opacities, and broncoalveolar lavage findings established a diagnosis of Pneumocystis carinii pneumonia (PCP). A high-resolution CT of the chest revealed peripheral infiltrates and low attenuation areas (LAA) consistent with severe emphysematous alterations. We administered high-dose methylprednisolone and trimethoprim-sulphamethoxazole (TMP-SMX). Because of marked eosinophilia, TMP-SMX was discontinued, and the patient was given inhaled pentamidine isothiocyanate. Although there was a striking clinical improvement, the emphysema-like lesion on chest CT remained unaltered. LAA on CT had been modest in 1994, but had markedly enlarged during the three years thereafter, leading us to speculate that most of the LAA lesions recognized on admission might have developed in association with PCP. Pulmonary function tests showed an obstructive ventilatory defect and impaired diffusing capacity. Although PCP classically presents with diffuse ground-glass or fine granular opacities, thin-walled cavities or other atypical findings have recently been reported, especially in AIDS patients. There have been several reports about emphysema-like lesions associated with PCP. It was suggested that these lesions might be due to lung parenchyma destruction induced by HIV itself or increased elastase release from HIV-infected macrophages. This is the first report of PCP with pulmonary emphysematous lesions in Japan.
Three newly synthesized imidazothiazole derivatives (N276-12, N276-14, N276-17) were examined regarding their ability and mechanism as a chemosensitizing agent against multidrug resistance 1 (MDR1)-mediated and multidrug resistance-associated protein (MRP)-mediated MDR. All three N276 compounds almost completely reversed the acquired resistance to vincristine (VCR), vinblastine (VBL), and doxorubicin (DXR) in MDR1-overexpressing human cancer cell lines (KB/VJ300 and T24/VCR). Their reversal effect against acquired resistance to VCR, DXR, and etoposide (VP16) was partial but clearly observed in the cell line expressing MRP (KB/VP4). All three N276 compounds enhanced the intracellular accumulation of [3H]VCR in MDR1-overexpressing KB/VJ300 cells through the inhibition of the increased efflux of the drug. They (100 microM) almost completely inhibited the photoaffinity labeling of P-glycoprotein encoded by the MDR1 gene. All the N276 compounds also remarkably enhanced the sensitivity to VBL and DXR in both MDR1- and MRP-overexpressing renal cell carcinoma (RCC) cell line (NKK1), whereas they showed no potentiation of these anticancer agents in an RCC cell line (KPK1) expressing neither MDR1 nor MRP. The combination chemotherapy of VCR or VP16 with N276-12 significantly increased the life span of mice inoculated i.p. or i.v. with drug-resistant P388/VCR cells without any significant side effects, whereas chemotherapy with the anticancer agent alone did not increase the life span at all. These results suggest that these newly synthesized imidazothiazole derivatives can be a useful chemosensitizing agent against not only MDR1- but also MRP-mediated MDR.
In order to clarify the regulatory mechanisms of periodontal regeneration by basic fibroblast growth factor (bFGF), effects of bFGF on proliferation, alkaline phosphatase activity, calcified nodule formation and extracellular matrix synthesis of human periodontal ligament (PDL) cells were examined in this study. bFGF enhanced the proliferative responses of PDL cells in a dose-dependent manner. The maximum mitogenic effect of bFGF on PDL cells was observed at the concentration of 10 ng/ml. In contrast, bFGF inhibited the induction of alkaline phosphatase activity and the mineralized nodule formation by PDL cells. Moreover, employing the reverse transcription-polymerase chain reaction (RT-PCR) technique, we observed that the levels of laminin mRNA of human PDL cells was specifically upregulated by bFGF stimulation, but that of type I collagen mRNA was downregulated. On the other hand, the expression of type III collagen and fibronectin mRNA were not altered even when the cells were activated by bFGF. These results suggest that suppressing cytodifferentiation of PDL cells into mineralized tissue forming cells, bFGF may play a role in wound healing by inducing growth of immature PDL cells and that in turn accelerates periodontal regeneration.
We examined the expression of interleukin (IL)-8 receptors (Rs), type A (IL-8-RA) and type B (IL-8-RB), on peripheral blood and bronchoalveolar lavage (BAL) fluid neutrophils; we also examined IL-8 and other chemoattractants in the epithelial lining fluid (ELF) of patients with chronic lower respiratory tract infection (CLI) to elucidate the in vivo regulation of IL-8Rs. Neutrophils were stained with monoclonal antibodies specific for IL-8-RA and IL-8-RB. We detected higher levels of IL-8 (81.6 +/- 25.4 ng/ml, mean +/- SE), leukotriene (LT) B4, and IL-1 beta in the ELF of the CLI patients than in their serum (P < 0.05). The expression of IL-8Rs on BAL neutrophils was significantly lower than that on peripheral blood neutrophils (P < 0.01 for both). In vitro analysis showed that low-level IL-8 (50 ng/ml) alone did not affect IL-8R expression but that it was downregulated by high-level IL-8 (500 ng/ml) alone and by low-level IL-8 in combination with LTB4 or IL-1 beta. Staurosporine reduced the downmodulation by low-level IL-8 plus LTB4 or IL-1 beta but not by high-level IL-8 alone. We speculate that pulmonary IL-8-RA and IL-8-RB may have been downmodulated by the combined effect of local chemoattractants through, in part, a protein kinase C-dependent mechanism.
A 68-year-old man, who had continuing exposure to budgerigars, developed fatal acute respiratory failure following years of slowly progressive pulmonary deterioration. His lung function was characterized first by mild airflow obstruction and later by progressive loss of lung volume. Computed tomography showed progressive development of pulmonary fibrosis and honeycombing. His serum disclosed precipitins to pigeon antigen. During his final illness his chest radiograph showed widespread patchy consolidation. At autopsy, his lungs revealed left lower lobe bronchopneumonia, fibrosis and honeycombing at the bases and widespread evidence of diffuse alveolar damage with organized exudate in some alveoli. To our knowledge, this is the second reported fatality due to acute alveolar injury in bird fanciers' lung.