著者

安本 篤史

出版者

一般社団法人 日本血栓止血学会

雑誌

日本血栓止血学会誌 (ISSN:09157441)

巻号頁・発行日

vol.32, no.6, pp.715-722, 2021 (Released:2021-12-25)

参考文献数

48

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新型コロナウイルスによるパンデミックを収束させるために複数のワクチンが開発され,世界中でワクチン接種が進められる中,アデノウイルスベクターワクチン接種後に血小板減少症を伴う血栓症(thrombosis with thrombocytopenia syndrome: TTS)の症例が報告された.TTSはヘパリン起因性血小板減少症と病態が類似しており,血小板を活性化させる抗血小板第4因子抗体が原因で非典型的な部位に血栓症(脳静脈洞血栓症や内臓静脈血栓症など)を引き起こし,血小板減少と凝固異常を合併しやすいため高率に出血を伴うために初期治療が遅れると致死率が高いことで知られる.mRNAワクチンではほとんど発症報告がないことや若年者での発症が多いことから,アデノウイルスベクターワクチンを中止する国もでてきて,世界規模でTTSの病態解明が行われている.TTSの情報は日々更新されているため本稿の内容もすぐに古い情報となる.本稿を土台にして常に情報を更新しつづけていただきたい.

著者

安本 篤史

出版者

一般社団法人 日本血液学会

雑誌

臨床血液 (ISSN:04851439)

巻号頁・発行日

vol.63, no.9, pp.1233-1241, 2022 (Released:2022-10-05)

参考文献数

45

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抗血小板第4因子(PF4)抗体は,抗PF4/heparin複合体抗体として知られ,heparin起因性血小板減少症(HIT)の診断目的で測定される。HITではheparin曝露により産生される抗PF4抗体が原因で血小板減少症と血栓症を引き起こす疾患であるが,2021年,新型コロナウイルス感染症に対して開発されたアデノウイルスベクターワクチン後に発症する致死的なワクチン起因性免疫性血栓性血小板減少症(VITT)に抗PF4抗体が関与していることが報告された。HITとVITTは抗PF4抗体が原因であるという点で合致し,病態も類似している一方,重症度が大きく異なり,また抗PF4抗体の測定法により検出感度が異なるなど合致しない点もみられる。本稿では抗PF4抗体に関連したHITとVITTについて概説する。

著者

高附 磨理 荒木 俊彦 菅野 陽 安本 篤史 森下 英理子 塩田 宏嗣

出版者

日本神経学会

雑誌

臨床神経学 (ISSN:0009918X)

巻号頁・発行日

vol.62, no.6, pp.487-491, 2022 (Released:2022-06-24)

参考文献数

13

被引用文献数

1

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基礎疾患のない48歳男性.ChAdOx1 nCoV-19ワクチン1回目を接種した10日後より頭痛を自覚.血液検査で,血小板数の低下,Dダイマーの上昇を認め,DICも合併していた.頭部単純CTにて左頭頂部に微小出血,造影CTにて左横静脈洞,左S状静脈洞に静脈洞血栓を認めた.その後施行した頭部MRIにて,左頭頂部に静脈性出血性梗塞,くも膜下出血,全身造影CTにて門脈血栓症,腎梗塞の所見を認めた.新型コロナワクチン接種後の血小板減少症を伴う血栓症(thrombosis with thrombocytopenia syndrome,以下TTSと略記)と診断し,手引きに準じて治療を行い,自宅退院となった.本症例は,ChAdOx1 nCoV-19ワクチンに伴うTTSの国内1例目と考えられる.

著者

友田 昌宏 安本 篤史 桑谷 立

出版者

日本情報地質学会

雑誌

情報地質 (ISSN:0388502X)

巻号頁・発行日

vol.31, no.2, pp.47-52, 2020-06-25 (Released:2020-06-25)

参考文献数

16

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電子線マイクロアナライザー(electron probe microanalyzer; EPMA)は,岩石中の鉱物の化学組成の空間分布を定量的に明らかにすることが可能であり,岩石形成プロセスの解明のために大きな威力を発揮する分析装置である.一方,岩石中に多数存在する鉱物種の空間分布を正確に把握し,点分析すべき箇所を適切に決定することは,岩石学の深い知識と経験が必要となり,一般的に容易ではない.本研究では,代表的なクラスター解析手法であるK平均法を基にして,面分析結果から,鉱物の空間分布および各鉱物種の代表組成となりうる座標の候補を出力するプログラムを開発した.

著者

吉田 健太 桑谷 立 安本 篤史 原口 悟 上木 賢太 岩森 光

出版者

日本地球惑星科学連合

雑誌

日本地球惑星科学連合2018年大会

巻号頁・発行日

2018-03-14

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Geochemical data from geological samples show compositional trends that reflect the material differentiation and assimilation occurred during certain geological processes. These trends often comprise groups in a multidimensional compositional space and are distributed in real space as geological units ranging from millimeters to kilometers in scale (e.g., Ueki and Iwamori, 2017). Therefore, spatial contextual information combined with chemical affinities could provide fundamental information about the sources and generation processes associated with the samples.However, conventional clustering algorithms such as k-means and fuzzy c-means (FCM) cluster analysis do not fully utilize the spatial distribution information of geologic samples. In this study, we propose a new clustering method for geochemical datasets with location coordinates. A spatial FCM algorithm originally constructed for image segmentation was modified to deal with a sparse and unequal-spaced dataset. The proposed algorithm evaluates the membership function modified using a weighting function calculated from neighboring samples within a certain radius.We applied new algorithm to a geochemical dataset of granitoids in the Ina-Mikawa district of the Ryoke belt that was compiled by Haraguchi et al. (2017), showing that samples collected from the same geological unit are likely to be classified as the same cluster. Moreover, overlapping geochemical trends are classified consistently with spatial distribution, and the result is robust against noise addition compared with standard FCM analysis.The proposed method can be calculated in the “GEOFCM” Excel® sheet provided as supplementary material and on our website (http://dsap.jamstec.go.jp). Geological datasets with precise location coordinates are becoming increasingly available, and the proposed method can help find overviews of complicated multidimensional data structure.

著者

安本 篤史 平島 崇男 中村 大輔 吉田 健太 桑谷 立

出版者

日本地球惑星科学連合

雑誌

日本地球惑星科学連合2018年大会

巻号頁・発行日

2018-03-14

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Eclogite from the Nové Dvory (ND), Czech Republic, in the Gföhl Unit of the Moldanubian Zone of the Bohemian Massif records extreme pressure and temperature conditions (>4GPa, >1000℃; Nakamura et al., 2004). The formation process of the ND eclogite is expected to give insights to understand tectonics of convergence zone at the deep depth. However, origins of the ND eclogite are controversial whether it was high-pressure cumulate (Medaris et al., 1995) or metagabbro (Obata et al., 2006). The controversy is partially due to ambiguous control factors of garnet zoning pattern in low-variant systems like bi-mineralic eclogite. For example, Nakamura et al. (2013) reported diverse zoning patterns of garnet within a thin-section scale of bi-mineralic eclogite. Their sample comprises a layer containing Fe-rich core garnet and another one containing Mg-rich core garnet. These zoned garnet grains show similar rim compositions. Nakamura et al. (2013) suggested that such zoning patterns are not only the result of changes in pressure and temperature conditions, but also in local bulk compositions. Yet, the origin of the mm-scale layering structure remained unclear. This study aims at revealing the formation process of the ND eclogite from the origin of the layering structure.The study samples are bi-mineralic eclogite composed of garnet-rich matrix and pyroxene-rich layer. Within each sample, garnet grains vary core compositions by layers, but show identical rim compositions regardless of their locations. For example, ND0207 contains a 3-mm thick pyroxene-rich layer. In ND0207, garnet grains in the garnet-rich matrix more than 10mm apart from pyroxene-rich layer has Mg-Cr-poor core (Fe:Mg:Ca=35:32:33 and Cr2O3<0.1wt%), those in the garnet-rich matrix near pyroxene-rich layer has Mg-rich Cr-poor core (Fe:Mg:Ca=23:55:22 and Cr2O3<0.1wt%), and those in pyroxene-rich layer has Mg-Cr-rich core (Fe:Mg:Ca=30:49:21, Cr2O3=1wt%). These garnet grains show similar rim compositions (Fe:Mg:Ca ≈ 28:42:30, Cr2O3 < 0.3 wt%), and contain omphacite only in their rim. Compositions of the omphacite inclusions are Na-rich in the garnet-rich matrix (Na2O=4-5wt%, Cr2O3<0.1wt%, XMg=Mg/(Mg+Fe) = 0.83-0.87), and Cr-Mg-rich in pyroxene-rich layer (Na2O=3-4wt%, Cr2O3<0.4wt%, XMg=0.85–0.90).Chemical compositions of the layering structure are determined by a quantitative mapping technique using electron probe micro analyzer (Yasumoto et al., under review). The result revealed that garnet-rich matrix increases Cr2O3 (0.0 to 0.3wt%) and XMg (0.5 to 0.8) from the relatively homogeneous part of the garnet-rich matrix to pyroxene-rich layer. This trend is concordant to the variation of chemical compositions of the minerals.The significant chemical variation of minerals suggests that the ND eclogite or its protolith was not produced only by accumulation. A comparison of (local) bulk compositions reveal that the garnet-rich matrix corresponds to the Gföhl eclogite (Beard et al., 1992; Medaris et al., 1995; Obata et al., 2006) and the gabbroic rocks from South Indian Ridge (Niu et al., 2002), whereas the pyroxene-rich layer corresponds to the Gföhl pyroxenites (Medaris et al., 1995). In addition, prograde relict amphibole is identified in the ND eclogite (Yasumoto et al., 2016), and the ND pyroxenite is considered to be accumulated from melt (Svojtka et al., 2016). These facts suggest that the ND eclogite was metagabbro that was partially infiltrated and metasomatised by pyroxenitic melt under high-pressure conditions. Chemical variation of garnet cores and lack of omphacite in the garnet cores indicate that the layering structure was present before the omphacite growth. In other words, the melt infiltrated before eclogite-facies metamorphism. Driving force of the changes in local bulk compositions can be prograde heating (Nakamura et al., 2013) or dehydration of amphibole during eclogitization.