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Dive into the research topics where Masanori Yokoba is active.

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Featured researches published by Masanori Yokoba.


Journal of Clinical Oncology | 2006

Phase II Trial of Amrubicin for Treatment of Refractory or Relapsed Small-Cell Lung Cancer: Thoracic Oncology Research Group Study 0301

Sayaka Onoda; Noriyuki Masuda; Takashi Seto; Kenji Eguchi; Yuichi Takiguchi; Hiroshi Isobe; Hiroaki Okamoto; Takashi Ogura; Akira Yokoyama; Nobuhiko Seki; Yoshiko Asaka-Amano; Masao Harada; Akihiro Tagawa; Hiroshi Kunikane; Masanori Yokoba; Kazutsugu Uematsu; Takayuki Kuriyama; Yumi Kuroiwa; Koshiro Watanabe

PURPOSE This multicenter, phase II study was conducted to evaluate the activity of amrubicin, a topoisomerase II inhibitor, against refractory or relapsed small-cell lung cancer (SCLC). PATIENTS AND METHODS SCLC patients with measurable disease who had been treated previously with at least one platinum-based chemotherapy regimen and had an Eastern Cooperative Oncology Group performance status of 0 to 2 were eligible. Two groups of patients were selected: patients who experienced first-line treatment failure less than 60 days from treatment discontinuation (refractory group), and patients who responded to first-line treatment and experienced disease progression > or = 60 days after treatment discontinuation (sensitive group). Amrubicin was administered as a 5-minute daily intravenous injection at a dose of 40 mg/m2 for 3 consecutive days, every 3 weeks. RESULTS Between June 2003 and December 2004, 60 patients (16 refractory and 44 sensitive) were enrolled. The median number of treatment cycles was four (range, one to eight). Grade 3 or 4 hematologic toxicities comprised neutropenia (83%), thrombocytopenia (20%), and anemia (33%). Febrile neutropenia was observed in three patients (5%). Nonhematologic toxicities were mild. No treatment-related death was observed. The overall response rates were 50% (95% CI, 25% to 75%) in the refractory group, and 52% (95% CI, 37% to 68%) in the sensitive group. The progression-free survival, overall survival, and 1-year survival in the refractory group and the sensitive group were 2.6 and 4.2 months, 10.3 and 11.6 months, and 40% and 46%, respectively. CONCLUSION Amrubicin exhibits significant activity against SCLC, with predictable and manageable toxicities; this agent deserves to be studied more extensively in additional trials.


American Journal of Respiratory and Critical Care Medicine | 2010

Inhaled granulocyte/macrophage-colony stimulating factor as therapy for pulmonary alveolar proteinosis.

Ryushi Tazawa; Bruce C. Trapnell; Yoshikazu Inoue; Toru Arai; Toshinori Takada; Yasuyuki Nasuhara; Nobuyuki Hizawa; Yasunori Kasahara; Koichiro Tatsumi; Masayuki Hojo; Haruyuki Ishii; Masanori Yokoba; Naohiko Tanaka; Etsuro Yamaguchi; Ryosuke Eda; Yoshiko Tsuchihashi; Konosuke Morimoto; Masanori Akira; Masaki Terada; Junji Otsuka; Masahito Ebina; Chinatsu Kaneko; Toshihiro Nukiwa; Jeffrey P. Krischer; Kohei Akazawa; Koh Nakata

RATIONALE Inhaled granulocyte/macrophage-colony stimulating factor (GM-CSF) is a promising therapy for pulmonary alveolar proteinosis (PAP) but has not been adequately studied. OBJECTIVES To evaluate safety and efficacy of inhaled GM-CSF in patients with unremitting or progressive PAP. METHODS We conducted a national, multicenter, self-controlled, phase II trial at nine pulmonary centers throughout Japan. Patients who had lung biopsy or cytology findings diagnostic of PAP, an elevated serum GM-CSF antibody level, and a Pa(O(2)) of less than 75 mm Hg entered a 12-week observation period. Those who improved (i.e., alveolar-arterial oxygen difference [A-aDO(2)] decreased by 10 mm Hg) during observation were excluded. The rest entered sequential periods of high-dose therapy (250 microg Days 1-8, none Days 9-14; x six cycles; 12 wk); low-dose therapy (125 microg Days 1-4, none Days 5-14; x six cycles; 12 wk), and follow-up (52 wk). MEASUREMENTS AND MAIN RESULTS Fifty patients with PAP were enrolled in the study. During observation, nine improved and two withdrew; all of these were excluded. Of 35 patients completing the high- and low-dose therapy, 24 improved, resulting in an overall response rate of 62% (24/39; intention-to-treat analysis) and reduction in A-aDO(2) of 12.3 mm Hg (95% confidence interval, 8.4-16.2; n = 35, P < 0.001). No serious adverse events occurred, and serum GM-CSF autoantibody levels were unchanged. A treatment-emergent correlation occurred between A-aDO(2) and diffusing capacity of the lung, and high-resolution CT revealed improvement of ground-glass opacity. Twenty-nine of 35 patients remained stable without further therapy for 1 year. CONCLUSIONS Inhaled GM-CSF therapy is safe, effective, and provides a sustained therapeutic effect in autoimmune PAP. Clinical trial registered with www.controlled-trials.com/isrctn (ISRCTN18931678), www.jmacct.med.or.jp/english (JMA-IIA00013).


Chest | 2014

Duration of Benefit in Patients With Autoimmune Pulmonary Alveolar Proteinosis After Inhaled Granulocyte-Macrophage Colony-Stimulating Factor Therapy

Ryushi Tazawa; Yoshikazu Inoue; Toru Arai; Toshinori Takada; Yasunori Kasahara; Masayuki Hojo; Shinya Ohkouchi; Yoshiko Tsuchihashi; Masanori Yokoba; Ryosuke Eda; Hideaki Nakayama; Haruyuki Ishii; Takahito Nei; Konosuke Morimoto; Yasuyuki Nasuhara; Masahito Ebina; Masanori Akira; Toshio Ichiwata; Koichiro Tatsumi; Etsuro Yamaguchi; Koh Nakata

BACKGROUND Treatment of autoimmune pulmonary alveolar proteinosis (aPAP) by subcutaneous injection or inhaled therapy of granulocyte-macrophage colony-stimulating factor (GM-CSF) has been demonstrated to be safe and efficacious in several reports. However, some reports of subcutaneous injection described transient benefit in most instances. The durability of response to inhaled GM-CSF therapy is not well characterized. METHODS To elucidate the risk factors for recurrence of aPAP after GM-CSF inhalation, 35 patients were followed up, monitoring for the use of any additional PAP therapies and disease severity score every 6 months. Physiologic, serologic, and radiologic features of the patients were analyzed for the findings of 30-month observation after the end of inhalation therapy. RESULTS During the observation, 23 patients remained free from additional treatments, and twelve patients required additional treatments. There were no significant differences in age, sex, symptoms, oxygenation indexes, or anti-GM-CSF antibody levels at the beginning of treatment between the two groups. Baseline vital capacity (% predicted, %VC) were higher among those who required additional treatment (P<.01). Those patients not requiring additional treatment maintained the improved disease severity score initially achieved. A significant difference in the time to additional treatment between the high %VC group (%VC≥80.5) and the low %VC group was seen by a Kaplan-Meier analysis and a log-rank test (P<.0005). CONCLUSIONS These results demonstrate that inhaled GM-CSF therapy sustained remission of aPAP in more than one-half of cases, and baseline %VC might be a prognostic factor for disease recurrence. TRIAL REGISTRY ISRCTN Register and JMACCT Clinical Trial Registry; No.: ISRCTN18931678 and JMAIIA00013; URL: http://www.isrctn.org and http://www.jmacct.med.or.jp.


Respiratory Physiology & Neurobiology | 2003

Respiratory muscle electromyogram and mouth pressure during isometric contraction.

Masanori Yokoba; Tadashi Abe; Masato Katagiri; Tomoyuki Tomita; Paul Easton

When extra-diaphragmatic muscles are activated progressively under approximately isometric conditions, we expect a corresponding increase in respiratory muscle output. Therefore, we examined relative recruitment shown as the latency to onset of EMG activity, and the relationship between mouth pressure and electromyogram activity of the neck accessory and transversus abdominis (TRANS) muscles during respiratory maneuvers against occlusion. Fine wire electrodes were inserted into the scalene (SCLN), sternocleidomastoid (STERNO), trapezius (TRAPZ) and TRANS in six awake, healthy subjects. Mouth pressure, raw and moving average EMG signals were recorded during gradual production of expiratory or inspiratory mouth pressure to maximum (MPmax) at FRC in the standing posture. Group mean linear regression lines of EMG activity versus mouth pressure were strongly significant for SCLN and TRANS, less for STERNO, and least for TRAPZ. The SCLN and STERNO showed EMG activities with low, and TRAPZ showed EMG activity only with high, mouth pressure. At 90% MPmax, TRAPZ was much less active compared with TRANS, SCLN, or STERNO. These results suggest that over a wide range of respiratory effort there is a significant difference in the relationship between mouth pressure and EMG activity in the accessory muscles, with differential recruitment of individual respiratory muscles.


Respiratory Medicine | 2012

Direct evidence that GM-CSF inhalation improves lung clearance in pulmonary alveolar proteinosis

Kazumasa Ohashi; Atsuyasu Sato; Toshinori Takada; Toru Arai; Takahito Nei; Yasunori Kasahara; Natsuki Motoi; Masayuki Hojo; Shinya Urano; Haruyuki Ishii; Masanori Yokoba; Ryosuke Eda; Hideaki Nakayama; Yasuyuki Nasuhara; Yoshiko Tsuchihashi; Chinatsu Kaneko; Hiroko Kanazawa; Masahito Ebina; Etsuro Yamaguchi; Jacqueline Kirchner; Yoshikazu Inoue; Koh Nakata; Ryushi Tazawa

BACKGROUND Autoimmune pulmonary alveolar proteinosis (aPAP) is caused by granulocyte/macrophage-colony stimulating factor (GM-CSF) autoantibodies in the lung. Previously, we reported that GM-CSF inhalation therapy improved alveolar-arterial oxygen difference and serum biomarkers of disease severity in these patients. It is plausible that inhaled GM-CSF improves the dysfunction of alveolar macrophages and promotes the clearance of the surfactant. However, effect of the therapy on components in bronchoalveolar lavage fluid (BALF) remains unclear. OBJECTIVES To figure out changes in surfactant clearance during GM-CSF inhalation therapy. METHODS We performed retrospective analyses of BALF obtained under a standardized protocol from the same bronchus in each of 19 aPAP patients before and after GM-CSF inhalation therapy (ISRCTN18931678, JMA-IIA00013; total dose 10.5-21 mg, duration 12-24 weeks). For evaluation, the participants were divided into two groups, high responders with improvement in alveolar-arterial oxygen difference ≥13 mmHg (n = 10) and low responders with that < 13 mmHg (n = 9). RESULTS Counts of both total cells and alveolar macrophages in BALF did not increase during the therapy. However, total protein and surfactant protein-A (SP-A) were significantly decreased in high responders, but not in low responders, suggesting that clearance of surfactant materials is correlated with the efficacy of the therapy. Among 94 biomarkers screened in bronchoalveolar lavage fluid, we found that the concentration of interleukin-17 and cancer antigen-125 were significantly increased after GM-CSF inhalation treatment. CONCLUSIONS GM-CSF inhalation decreased the concentration of total protein and SP-A in BALF, and increase interleukin-17 and cancer antigen-125 in improved lung of autoimmune pulmonary alveolar proteinosis.


International Journal of Clinical Oncology | 2009

Effect of gefitinib on warfarin antithrombotic activity.

Susumu Arai; Hisashi Mitsufuji; Yasuto Nishii; Sayaka Onoda; Shinichiro Ryuge; Mayuko Wada; Ken Katono; Maiko Iwasaki; Akira Takakura; Sakiko Otani; Michiko Yamamoto; Tomoko Yanaihara; Masanori Yokoba; Masaru Kubota; Masato Katagiri; Tomoya Fukui; Hirosuke Kobayashi; Nobuo Yanase; Noriyuki Masuda

BackgroundDespite the literature indicating adverse interactions between warfarin and cytotoxic agents, whether such an interaction occurs when warfarin and gefitinib are used concomitantly is unknown. We analyzed the prevalence of the concomitant use of warfarin and gefitinib, and the incidence of prothrombin time-international normalized ratio (PT-INR) alterations or adverse interactions in concomitant users of warfarin and gefitinib.MethodsWe conducted a retrospective study of patients with non-small cell lung cancer treated at the Kitasato University Hospital who received concomitant warfarin and gefitinib between September 2002 and January 2007. Medical information, including the indication for warfarin use, warfarin dosing and dosing changes, and exposure to gefitinib were collected from computerized databases and medical records.ResultsTwelve (4.1%) of 296 patients treated with gefi— tinib received warfarin. PT-INR elevation occurred in 6 patients (50.0%). Two (16.7%) of the 12 patients had liver metastases. Liver dysfunction was associated with PT-INR elevation (P = 0.0100).ConclusionAs there is a possibility of PT-INR abnormalities occurring during the concomitant use of gefitinib and warfarin, clinicians should be aware of this interaction. Because of the potentially severe consequences of this interaction, close monitoring of PT-INR and warfarin dose adjustment are recommended for patients receiving warfarin and gefitinib, especially during the first 2 weeks in the beginning of warfarin therapy.


Chest | 2010

Parasternal Muscle Activity Decreases in Severe COPD With Salmeterol-Fluticasone Propionate

Paul Easton; Harvey G. Hawes; Christopher Doig; Malcolm Johnson; Masanori Yokoba; Eric Wilde

BACKGROUND The effect of the long acting beta(2)-agonist/corticosteroid combination salmeterol-fluticasone propionate (SFC) on respiratory muscles and ventilation in severe COPD is unknown. As COPD hyperinflation worsens, diaphragm efficiency decreases, and a compensatory increase in chest wall inspiratory muscle activity occurs. If a bronchodilator successfully alleviates hyperinflation and improves diaphragm efficiency in severe COPD, then the extraordinary activation of the chest wall may be relieved. We examined directly the effect on the parasternal intercostal respiratory chest wall muscle and ventilation of four puffs of salmeterol 25 microg and fluticasone propionate 125 microg via the metered dose combination inhaler in 12 patients with severe Global Initiative on Obstructive Lung Disease stage III-IV COPD, mean FEV(1) = 0.91 L (32% predicted). METHODS We measured parasternal intercostal electromyogram (EMG) recorded from implanted fine-wire electrodes, ventilation, and breathing pattern, during resting and CO(2)-stimulated breathing. Full pulmonary function tests were recorded at the beginning and end of the study. RESULTS In this patient group, severe airflow obstruction and hyperinflation were poorly reversible after SFC: FEV(1) increased 4.2%, functional residual capacity decreased 1.4%, and inspiratory capacity increased 5.9%. However, with SFC there was a significant increase in minute ventilation, tidal volume, and mean inspiratory flow. There was a very large decrease in directly recorded parasternal EMG, with parasternal EMG disappearing completely in some patients after SFC. CONCLUSIONS In severe COPD, with minimal change in hyperinflation or pulmonary mechanics, salmeterol-fluticasone induced a significant decrease in activity of the chest wall parasternal inspiratory muscle. This may be of practical benefit to reverse the extensive use of the chest wall muscles and alleviate dyspnea in severe COPD.


Clinical Science | 2013

Angiotensin-converting enzyme inhibition curbs tyrosine nitration of mitochondrial proteins in the renal cortex during the early stage of diabetes mellitus in rats

Naohito Ishii; Pamela K. Carmines; Masanori Yokoba; Hiroyuki Imaizumi; Tsuyoshi Ichikawa; Hideki Ikenagasa; Yoshio Kodera; Masamichi Oh-Ishi; Yoshikazu Aoki; Tadakazu Maeda; Tsuneo Takenaka; Masato Katagiri

Experiments were performed to evaluate the hypothesis that ACE (angiotensin-converting enzyme) inhibition (enalapril) suppresses 3-NT (3-nitrotyrosine) production in the renal cortex during the early stage of Type 1 DM (diabetes mellitus) in the rat. Enalapril was administered chronically for 2 weeks to subsets of STZ (streptozotocin)-induced DM and vehicle-treated sham rats. O2− (superoxide anion) and NOx (nitrate+nitrite) levels were measured in the media bathing renal cortical slices after 90 min incubation in vitro. SOD (superoxide dismutase) activity and 3-NT content were measured in the renal cortex homogenate. Renal cortical nitrated protein was identified by proteomic analysis. Renal cortical production of O2− and 3-NT was increased in DM rats; however, enalapril suppressed these changes. DM rats also exhibited elevated renal cortical NOx production and SOD activity, and these changes were magnified by enalapril treatment. 2-DE (two-dimensional gel electrophoresis)-based Western blotting revealed more than 20 spots with positive 3-NT immunoreactivity in the renal cortex of DM rats. Enalapril treatment blunted the DM-induced increase in tyrosine nitration of three proteins ACO2, GDH1 and MMSDH (aconitase 2, glutamate dehydrogenase 1 and methylmalonate-semialdehyde dehydrogenase), each of which resides in mitochondria. These data are consistent with enalapril preventing DM-induced tyrosine nitration of mitochondrial proteins by a mechanism involving suppression of oxidant production and enhancement of antioxidant capacity, including SOD activation.


Respiratory Physiology & Neurobiology | 2008

Aminophylline increases parasternal intercostal muscle activity during hypoxia in humans.

Yasuto Nishii; Yasumasa Okada; Masanori Yokoba; Masato Katagiri; Tomoko Yanaihara; Noriyuki Masuda; Paul Easton; Tadashi Abe

To clarify the mechanism of action of aminophylline on the hypoxic ventilatory response in humans, we analyzed the effects of aminophylline on respiratory neural output. To evaluate the respiratory neural output, we analyzed the electromyogram (EMG) of the parasternal intercostal muscle, one of the major inspiratory muscles, in eight healthy subjects. Both before and during aminophylline administration, measurements of ventilatory parameters with EMG recordings were conducted in room air, mild hypoxia (F(I)(o)(2) 0.15), and severe hypoxia (F(I)(o)(2) 0.11). Before administering aminophylline, hypoxic stimulation elicited ventilatory augmentation in a hypoxia-intensity dependent manner. Administration of aminophylline caused significant increases in ventilation (V (I)), tidal volume (V(T)), respiratory frequency (f(R)), and the respiration-related phasic moving averaged EMG amplitude (tidal EMG), at corresponding levels of hypoxia compared to before aminophylline. Augmentation patterns of hypoxia-induced increases in V(T) and tidal EMG showed close similarity. These results indicate that augmentation of hypoxic ventilatory response by aminophylline is mainly mediated by an increase in the respiratory neural drive in healthy humans.


Pulmonary Pharmacology & Therapeutics | 2015

Aminophylline increases respiratory muscle activity during hypercapnia in humans

Masanori Yokoba; Tsuyoshi Ichikawa; Akira Takakura; Naohito Ishii; Yuya Yamada; Tomoaki Tsukushi; Noriyuki Masuda; Paul Easton; Masato Katagiri

BACKGROUND Theophylline is an old drug traditionally used as a bronchodilator, although it was recently shown to possess anti-inflammatory properties, enhance the actions of corticosteroid actions, and stimulate the respiratory neuronal network. Theophylline has been recognized as an important drug for not only asthma but also corticosteroid-insensitive chronic obstructive pulmonary disease (COPD). To clarify the role of theophylline in hypercapnic ventilatory responses in humans, we analyzed the effects of aminophylline administered at the usual clinical therapeutic doses on ventilation and augmentation of respiratory muscle contractility in room air and under 3 conditions of hypercapnia. STUDY DESIGN We performed electromyography (EMG) of the parasternal intercostal muscle (PARA) and transversus abdominis muscle (TA) in 7 healthy subjects and recorded both ventilatory parameters and EMG data in room air and under 3 conditions of hypercapnia before (control) and during aminophylline administration. RESULTS Before aminophylline administration (control), hypercapnic stimulation elicited ventilatory augmentation in a hypercapnia intensity-dependent manner. Ventilatory parameters (tidal volume, frequency of respiration, and minute ventilation) showed significant increases from lower PaCO2 levels during aminophylline administration when compared with the corresponding values before aminophylline administration. EMG activity of both PARA and TA increased significantly at each level of hypercapnia, and those augmentations were shown from lower PaCO2 levels during aminophylline administration. CONCLUSION Aminophylline administered at the usual clinical therapeutic dose increases ventilation and EMG activity of both inspiratory and expiratory muscles during hypercapnia in healthy humans.

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