Masahiro Nagai

Dr. Masahiro Nagai


Research Focus & Metrics

Academic Career Length

33Years (1994-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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15 September 2001 in Blood
Verified
Journal Article
Open access
MNMasahiro Nagai
Masahiro Nagai
MBMeghan Brennan
Meghan Brennan
JSJill A. Sakai
Jill A. Sakai
CMCarlos A. Mora
Carlos A. Mora
SJSteven Jacobson
Steven Jacobson
It is thought that human T-cell lymphotropic virus type I (HTLV-I) preferentially infects CD4+ T cells in vivo. However, observations of high HTLV-I proviral load in patients with HTLV-I–associated myelopathy/tropical spastic paraparesis suggest that HTLV-I may infect other cell types in addition to CD4+ T cells. To identify in vivo T-cell tropisms of HTLV-I, real-time quantitative polymerase chain reaction (PCR) and intracellular protein staining were used. A high amount of HTLV-I proviral DNA was detected from purified CD8+ T cells by quantitative PCR (between 1.64 and 62.83 copies of HTLV-I provirus per 100 isolated CD8+ T cells). CD8+ T cells expressed HTLV-I–related antigens (HTLV-I Tax and p19 protein) after a short time in cultivation. These results demonstrate that CD8+ T cells are also infected with HTLV-I and express HTLV-I antigens at levels that are comparable to HTLV-I–infected CD4+ cells. Therefore, CD8+ cells are an additional viral reservoir in vivo for HTLV-I and may contribute to the pathogenesis of HTLV-I–mediated disorders.

8 December 2014 in Neurology and Clinical Neuroscience
Verified
Journal Article
Closed access
PDF file
HIHirotaka Iwaki
Hirotaka Iwaki
NNNoriko Nishikawa
Noriko Nishikawa
MNMasahiro Nagai
Masahiro Nagai
TTTomoaki Tsujii
Tomoaki Tsujii
HYHayato Yabe
Hayato Yabe
MNMasahiro Nomoto
Masahiro Nomoto

1 November 2015 in Clinical Neuropharmacology
Verified
Journal Article
Closed access
MNMasahiro Nomoto
Masahiro Nomoto
SKShin-Ichiro Kubo
Shin-Ichiro Kubo
MNMasahiro Nagai
Masahiro Nagai
TYTatsuo Yamada
Tatsuo Yamada
ATAkira Tamaoka
Akira Tamaoka
NHNobutaka Hattori
Nobutaka Hattori
This study is the first controlled trial to evaluate the efficacy and safety of subcutaneous apomorphine in Japanese patients with advanced Parkinson disease. A phase II, multicenter, randomized, double-blind, parallel-group trial was undertaken in 16 patients with advanced Parkinson disease with wearing-off phenomenon to compare subcutaneous apomorphine versus placebo. The maintenance dose of apomorphine (1-6 mg per dose), determined individually for each patient by titration, was additionally administered 3 times at 2-hour intervals in the multiple-dose phase in which pharmacokinetics was evaluated. The mean (SD) maintenance apomorphine dose was 3.4 (1.4) mg (range, 2-6 mg). The change in the Unified Parkinson's Disease Rating Scale motor score 20 minutes after maintenance dose administration was significantly greater in the apomorphine group than in the placebo group (least squares mean, -24.0 vs -4.1, P = 0.021). Apomorphine treatment resulted in an "on" state approximately 20 minutes after dose administration, lasting for approximately 60 minutes. Apomorphine was rapidly absorbed, with the maximum plasma concentration (Cmax) reached in 0.367 to 0.383 hour. It was quickly eliminated with a half-life of 0.520 to 0.793 hour, suggesting no accumulation during multiple-dose phase. The Cmax of apomorphine at effective dose was presumed to be approximately 20 ng/mL. Apomorphine was well tolerated. Subcutaneous apomorphine is expected to provide a new treatment option in Japan as a rescue therapy. Two-hour interval injections did not cause reduced responses, and effective blood concentration was presumed to be approximately 20 ng/mL similar, to the previous study conducted at North America.

1 January 1996 in YAKUGAKU ZASSHI
Verified
Journal Article
Open access
PDF file
NSNobuko Sakurai
Nobuko Sakurai
MNMasahiro Nagai
Masahiro Nagai
Cimicifugae Rhizoma have been used as an anti-inflammatory, analgesic and antipyretic remedy in the traditional Chinese medicines. Many 9,19-cyclolanostane glycosides have been isolated from Cimicifuga and related genera. Two biogenetically key compounds, acetylshengmanol xyloside and cimicifugoside H-1, were isolated and their chemical structures were elucidated by our group. The former compound seems to be the parent component of the other glycosides such as cimigenol xyloside from C. dahurica, C. iaponica and C. acerina. The latter glycoside, cimicifugoside H-1 was isolated together with cimicifugosides H-2-H-6 from commercial Cimicifugae Rhizoma. They are novel glycosides having a hydroxyl group ay C-11, and cimicifugosides H-3, H-4 and H-6 were trinor-triterpenol glycosides. Cimicifugoside H-1 changed into H-2, H-3 and H-4 under acidic or alkaline conditions. In this review, the structure elucidation of the above glycosides and their chemical transformation into other Cimicifuga glycosides are described.

1 January 2015 in Japanese Clinical Medicine
Verified
Journal Article
Open access
NNNoriko Nishikawa
Noriko Nishikawa
MNMasahiro Nagai
Masahiro Nagai
TTTomoaki Tsujii
Tomoaki Tsujii
WKWin T. Kyaw
Win T. Kyaw
NTNachi Tanabe
Nachi Tanabe
MNMasahiro Nomoto
Masahiro Nomoto
The number of patients with late-onset myasthenia gravis (MG) among patients ≥50 years has been increasing recently. We encountered three patients who developed elderly-onset MG at a particularly advanced age (≥80 years). All were female and positive for anti-acetylcholine receptor antibodies. About 4 years have passed since MG onset in all three patients and symptoms have been controlled without recurrence using a combination of oral low-dose prednisolone and tacrolimus. As many cases of elderly-onset MG do not require strong immunosuppression, we recommend minimum immunosuppressive treatment to avoid adverse events, particularly in patients at an advanced age of ≥80 years.

1 January 2009 in Parkinsonism & Related Disorders
Verified
Journal Article
Closed access
MNMasahiro Nomoto
Masahiro Nomoto
NNNoriko Nishikawa
Noriko Nishikawa
MNMasahiro Nagai
Masahiro Nagai
HYHayato Yabe
Hayato Yabe
ANAkiko Nakatsuka
Akiko Nakatsuka
MKMadoka Kubo
Madoka Kubo