{"created":"2023-06-19T07:18:01.369907+00:00","id":3153,"links":{},"metadata":{"_buckets":{"deposit":"1a0e52af-cb51-403c-880c-8a1bb66a3080"},"_deposit":{"created_by":4,"id":"3153","owners":[4],"pid":{"revision_id":0,"type":"depid","value":"3153"},"status":"published"},"_oai":{"id":"oai:az.repo.nii.ac.jp:00003153","sets":["370:15:391"]},"author_link":["16156"],"item_10006_date_granted_11":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2006-03-15"}]},"item_10006_degree_grantor_9":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"麻布大学"}]}]},"item_10006_degree_name_8":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士(獣医学)"}]},"item_10006_description_22":{"attribute_name":"Abstract","attribute_value_mlt":[{"subitem_description":"Duchenne muscular dystrophy (DMD) is a hereditary disorder in human characterized by progressive muscular degeneration and necrosis. Clinically, it is marked by progressive muscular atrophy and weakness. DMD is caused by a mutation in a gene for a cytoskeletal protein called dystrophin, resulting in dysfunctional or deficient protein. Dystrophin is a key structure in the dystrophin-glycoprotein complex (DGC). The loss of dystrophin thus leads to destruction of the DGC in the sarcolemma, which in turn initiates a cascade of events in skeletal and cardiac myocytes, including membrane damages during muscle contraction, cellular destruction and replacement by fibrosis and fatty infiltration.\n The clinical manifestation includes abnormal gait due to muscle weakness and atrophy, difficulty walking, respiratory insufficiency and reduced cardiac function. These symptoms advance gradually and progressively, and in most patients death occurs unexpectedly at a young age or dead typically from respiratory failure, pneumonia or chronic cardiac failure. Recent advancements in medicine have reduced the risk of death from respiratory failure and prolonged the life span of DMD patients. On the other hand, cardiac failure is still the primary cause of death in DMD, as it is treated only conservatively. As such, development of a better animal model of DMD and characterization of cardiomyopathy in the model are promising approaches for pathophysiological understanding and development of therapeutic options for cardiac dysfunction in DMD. Further, these studies have a future potential in companion animal medicine to contribute to the therapy of canine X-linked muscular dystrophy (CXMD), which shares the same genetic background with DMD. To this end, the clinical and pathological presentations of cardiac dysfunction were characterized in dogs with Japanese CXMD(CXMD_J) in this study.\n Although CXMD_J shares the same genetic background with DMD, its phenotype is ill defined. In Chapter 2, the phenotype of CXMD_J, i.e., clinical symptoms and cardiac function, was examined in dogs with CXMD_J. In Chapter 3, to understand the course of cardiac alteration in CXMD_J, postnatal development of cardiomyopathy was followed in dogs with CXMD_J until 21 months of age. In Chapter 4, electrophysiological and histopathological studies were performed to analyze the results in Chapters 2 and 3 and to understand the pathology of cardiomyopathy in more detail. The results of this study provided a clue to the pathogenesis of cardiomyopathy in CXMD_J and demonstrated the usefulness of CXMD_J as an animal model of DMD.\n\nChapter 2: Evaluation of clinical symptoms and cardiac function in CXMD_J\n\n On average, DMD patients develop clinical symptoms at 1.5 years of age and are diagnosed by age 5. Skeletal muscle degeneration generally starts as weakness or atrophy in the pelvicrural muscle and quadriceps and spreads to the shoulder blade and upper limbs. These symptoms are typically accompanied by pseudohypertrophy of calf muscles. By the age of 10, most patients lose ability to walk and often develop macroglossia and thoracic deformity, which are followed by respiratory muscle disorder and cardiomyopathy. Electrocardiogram (ECG) demonstrates abnormalities such as sinus tachycardia and deep, narrow Q waves in lead I, aVL, V5 and V6. Echocardiography may reveal a high-echo density in the left ventricular posterior wall. In this part of the study, physical examination, ECG and echocardiography were performed in dogs with CXMD_J at 5, 7 and 1O months of age. At 5 months, the dogs had already developed macroglossia, sialorrhea and atrophy in the temporal muscles. At 7 months, abnormal vocalization and muscle contractures in the proximal limbs were observed. There was no further progression in clinical symptoms at 10 months of age. ECG revealed deep Q waves at 5 months and an increased Q/R ratio in lead II, III and aVF. In one dog, a high-echo region was found near the left ventricular papillary muscle by echocardiography. These results indicated that clinical manifestations of CXMD_J were very similar to those of GRMD.\n\nChapter 3: Time course analysis of clinical development and the onset of cardiomyopathy in CXMD_J\n\n In Chapter 2, clinical, ECG and echocardiographic analyses outlined the course and manifestations of CXMD_J and indicated that these findings were similar to those of GRMD. In this chapter, the earlier development of CXMD_J was followed in further detail. As a result, clinical symptoms appeared as early as 3 months of age and progressively developed until about 6 months. Thereafter, the symptoms remained stable. ECG showed deep Q waves and increased Q/R in lead II, III and AVF from 7 weeks of age. No morphological abnormality or cardiac dysfunction was found by echocardiography. A heart rate variability analysis of 24-hr ECG at the age of 5, 8, 12 and 17 months showed continuously elevated heart rates as well as frequent incidences of ventricular arrhythmia in dogs with CXMD_J compared to the control dogs. In addition, dogs with CXMD_J showed smaller diurnal variability in the average high frequency power (HF), and the low frequency/high frequency (LF/HF) ratio was decreased during the day and increased at night. These findings were also similar to those in DMD and were indicative of disturbance in the autonomic nervous function. From these results, it was found that clinical symptoms and abnormal ECG readings appeared as early as 3 months old in CXMD_J. Furthermore, early asymptomatic myocardial abnormalities were detected by heart rate variability analysis, which implicated autonomic nervous dysfunction, as well as by ECG and blood test as forms of arrhythmia.\n\nChapter 4: Analysis of ventricular impulse propagation in CXMD_J using the CARTO system\n\n The analyses in Chapter 2 and 3 elucidated the timing of the onset of clinical symptoms and ECG abnormalities in dogs with CXMD_J. These studies also revealed autonomic disturbance, which had not been reported previously. However, the link between the ECG abnormalities and cardiomyopathy remains to be studied. To determine the cause of observed ECG abnormalities, the cardiac electrophysiology of CXMD_J was analyzed using the CARTO system in this chapter. Autopsy was also performed for histopathological analysis. The CARTO analysis performed in the control dogs and CXMD_J dogs at 5, 9 and 21 months of age revealed a difference in ventricular impulse conduction between these dogs. In the control dogs at 5 and 9 months, the action potentials started from the interventricular septum and spread to the left ventricular free wall, the apex and to the right ventricle. The impulse terminated in the cardiac base. This sequence of ventricular electric activation was similar to that of healthy adult dogs. However, in 5- and 9-month-old dogs with CXMD_J, the ventricular impulse was initiated at the cranial region of the left ventricular free wall, not at the interventricular septum. The impulse then bifurcated to the apex and to the interventricular septum, indicating that the mode of ventricular electric conduction is different from that of the control dogs. At 21 months of age, the control dogs showed similarly normal impulse propagation in the ventricles. In 21-month-old CXMD_J dogs impulse conduction was different from those observed at 5 and 9 months and delayed in island-shaped regions along the lateral side of the left ventricular free wall. These observations suggested that, in CXMD_J, the impulse traveling from the left ventricular free wall to the interventricular septum was responsible for deep Q waves observed by ECG\n By histopathological analysis, no degeneration was found in ordinary cardiac muscle fibers in young CXMD_J dogs. However, fiber degeneration was evident in CXMD_J dogs older than 15 months. In contrast, degeneration of specialized cardiac fibers (i.e., Purkinje fibers) was observed at 5 months of age. Together, the delayed impulse conduction in the left ventricle in 21-month-old CXMD_J dogs was thought to be a consequence of altered vector potentials due to degeneration in ordinary cardiac muscle fibers and Purkinje fibers\n\nConclusion and Prospectus\n\n The present study confirmed that clinical presentations and ECG abnormalities in CXMD_J closely resemble to those of GRMD. A novel form of abnormality in ECG, autonomic disturbance were also found during early development of CXMD_J. Further, cardiac impulse conduction is altered in CXMD_J, and histopathological examination revealed degeneration of Purkinje fibers. These characteristics are novel and have not been reported in previous studies of DMD, Golden Retriever muscular dystrophy (GRMD) and CXMD. The study demonstrated that CXMD_J is an excellent animal model for characterization of DMD pathology, especially for pathogenesis of clinically important cardiomyopathy. The model is also promising in understanding the pathology of CXMD in veterinary medicine.\n\n","subitem_description_type":"Other"}]},"item_10006_description_7":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"ヒトにおけるDuchenne muscular dystrophy (DMD)は、進行性の筋肉変性、壊死を主病変とし、臨床的には進行性の筋萎縮および筋力低下を生じる遺伝性の疾患である。DMDは、ジストロフィン遺伝子の異常により細胞骨格蛋白質であるジストロフィンに異常をきたすために生じる。ジストロフィンはDGC (dystrophin-glicoprotein-complex) の主要な構成成分であり、ジストロフィンの異常は、筋線維鞘(sarcolemma)のDGC消失につながる。すなわち筋収縮に際し、細胞膜の損傷を招来し細胞破壊が生じる結果、骨格筋および心筋において脂肪浸潤および結合組織置換などの進行性変性が生じる。臨床的には、筋力低下および萎縮に伴う歩様異常、歩行困難ならびに呼吸機能低下、さらに心機能低下などが認められ、それらは次第に進行し、ほとんどの患者が呼吸不全、肺炎、慢性心不全あるいは突然死により若齢で死亡する。近年、医療の進歩により呼吸不全による死亡のリスクが減少し、ライフスパンが長くなっている一方で、心不全においては保存的治療を余儀なくされ、DMDにおける死因の重要な原因になっている。よりよいDMDモデル動物を確立し、その心機能障害を解明することは、DMDにおける心不全に対する病態の解明ならびに治療法開発に大きく貢献すると考えられる。さらに将来的に伴侶動物の医療における筋ジストロフィー動物の治療にも貢献するものと思われる。これまでにゴールデン・レトリーバーX連鎖性筋ジストロフィー (GRMD) がモデル動物として用いられているが、大型であることから飼育管理が難しく、形質の維持に大きな労力を費やすなどの問題もあり、より優れたモデル動物の導入が必要とされてる。以上のことから本研究は、DMDと同様の遺伝異常を持つCanine X-Linked Muscular dystrophy in Japan(CXMD_J)における心機能障害の病態について検討を行った。\n　CXMD_Jは、DMDと遺伝的背景は同様であるが、心機能障害についての詳細な検討はなされていない。第2章ではCXMDJにおける臨床徴候、および心機能について評価を行った。さらに、CXMDJにおける詳細なる心機能障害を把握するため、第3章では、出生時より生後21ヵ月齢まで経時的に検査を行いその動向について検討を加えた。第4章では、第2章および第3章において得られた成績についてさらに電気生理学および病理組織学的検討を加え、心筋障害の病態について検討した。これらの結果からCXMDJにおける心筋障害のメカニズムを解明する手がかりが得られ、ならびにCXMDJのDMDモデル動物としての有用性が示唆された。\n【第2章】CXMD_Jにおける臨床徴候および心機能の評価。\n　DMD患者は、2歳で臨床徴候が認められ、5歳までに診断される。骨格筋病変として腰帯筋、大腿四頭筋の筋力低下および萎縮に始まり、ついで肩甲骨、四肢近位部に波及し、腓腹筋の仮性肥大を伴う。、しばしば巨舌などを生じ、さらに胸郭変形および呼吸筋、心筋障害を発現し、10歳前後で歩行不能となる。心電図上の所見としてI、aVL、V5ならびにV6誘導あるいは、II、III、aVF誘導における深く幅の狭いQ波の出現、洞性頻脈等の異常がみられる。心エコー上左心室後壁に高信号所見を認める例もみられる。CXMD_Jにおいて生後5ヶ月齢、7ヶ月齢、および10ヶ月齢時に身体検査、心電図検査ならびに心エコー検査を実施した。その結果、生後5ヶ月齢時、既に巨舌、流涎および側頭筋の萎縮が認められ、生後7ヶ月齢時では、異常発声ならびに体幹近位部における四肢筋肉の硬縮が認められた。その後は臨床徴候の悪化は認められなかった。生後5ヶ月齢ですでにQ波振幅の増大、Q/R比の増大がII、IIIおよびaVF誘導において認められた。心エコー検査においては、1例にのみ左心室乳頭筋領域に高エコー所見が認められた。以上のことから、CXMD_JはGRMDと酷似していることが確認された。\n【第3章】CXMD_Jにおける臨床徴候および心機能障害出現時期と経時的変化について\n　第2章においてCXMD_Jにおける臨床所見、心電図ならびに心エコー所見での概要が確認され、GRMDの所見と類似することが確認された。そこで本章では、その詳細についてさらに若齢期から経時的観察を実施し検討を加えた。その結果、CXMD_Jにおいて臨床徴候は生後3ヶ月齢より発現して、生後6ヶ月齢ころまで進行し、その後は小康状態で推移することが判明した。心電図検査においては、生後7週齢よりII、III、AVF誘導においてQ波振幅の増大およびQ/R比の増大が認められた。心エコー上、生後21ヶ月齢の時点では、心機能低下および形態学的な異常は認められなかった。生後5ヶ月齢、8ヶ月齢、12ヶ月齢および17ヶ月齢における24時間心電図による心拍変動解析の結果、CXMD_Jは対照犬と比較し、心拍数は一貫して高く保時され、また心室性不整脈の発現数が多い傾向が認められた。さらにCXMD_JはHF powerの日内変動が小さくLF/HFは日中低下し、夜間上昇する結果となった。すなわちDMD患者と同様の傾向を示し、自律神経機能に変化が生じていることが示唆された。\n　これらの結果よりCXMD_Jでは生後3ヶ月齢より臨床徴候および心電図において異常を呈することが明らかとなった。さらに、心拍変動解析では自律神経機能に変化を来たしており、不整脈の出現状況においても異常が認められたことから、顕性化する以前における心機能の異常をdetectしていることが示唆された。\n【第4章】CXMD_JにおけるCARTOシステムによる心室興奮伝播様式の検討\n　第2章および第3章の成績より、CXMDJ犬における臨床徴候、および心電図異常の発現時期が明らかとなり、さらにこれまで知られていなかった不整脈の出現および、自律神経機能に変化を生じていることなどの所見が得られた。しかしながら心電図の異常所見と心筋障害との関係は明らかにされておらず、心電図異常の成因は不明のままである。第4章では、心電図異常の成因を解明する目的でCARTOシステムを用いた電気生理学的検討を行うと同時に、病理解剖を実施し、病理組織学的検討を行った。CARTOシステムによる解析は、生後5ヶ月齢、9ヶ月齢および21ヶ月齢の対照犬およびCXMD_J犬について実施した。その結果、対照犬とCXMD_J犬では心室の興奮伝播様式に相違のあることが判明した。すなわち生後5ヶ月齢および9ヶ月齢の対照犬では、電気的興奮刺激が心室中隔から開始されついで左心室自由壁側、心尖部さらに右心室方向へと伝播し、最終的に心基底部に向かい終息する様式をとり、正常犬の心電図興奮伝播における概念と一致した所見が得られた。しかしながら、同時期のCXMD_J犬においては、心室の興奮開始部位は心室中隔ではなく、左心室自由壁上方であることが確認された。さらに興奮刺激は、左心室自由壁を心尖部方向へ向かうと同時に、心室中隔に向かって伝播する現象が捉えられ、対照犬と異なる電気的興奮伝播様式をとることが確認された。生後21ヶ月齢においても対照犬は、上記の対照犬と同様の心室興奮伝播様式をとることが確認された。生後21ヶ月齢のCXMD_Jにおいては、左心室自由壁の側壁に島状に興奮伝播の遅延する領域が認められ、生後5ヶ月齢および9ヶ月齢のCXMD_Jにおける伝播様式とは異なる様相を呈した。CXMD_J犬では、左心室自由壁から心室中隔に興奮が伝播することから、心電図Q波として表現される可能性があるものと推察された。\n　病理組織検査においては、個体差はあるものの若齢では固有心筋線維に変性を生じず、生後15ヶ月齢以上では固有心筋線維に変性が生じることが判明した。さらに特殊心筋線維(プルキンエ線維)においては生後5ヶ月齢で、すでに変性を生じることが確認された。生後21ヶ月齢におけるCXMD_J犬において心室の興奮伝播に遅延部位を認めた原因として、病理組織検査成績を考え合わせると、固有心筋および特殊心筋の変性がベクトル電位に変化をきたしたものと推察された。\n【総括】\n　以上本研究において、CXMD_JがGRMDの臨床所見および心電図異常所見と酷似していることが確認された。さらに、若齢期におけるCXMD_J犬の心電図異常、ならびに自律神経機能の変化、さらに心室興奮伝播様式の変化が確認され、さらに病理組織検査においてもプルキンエ線維の変性などの所見が認められた。これらの所見はこれまでのDMD、GRMDおよびCXMDにおける報告では言及されていない新たな所見であり、今回用いたCXMD_J犬はDMDの病態解明、特に重要な心機能障害の解明に非常に有用なモデル動物であることか確認されたと同時に、獣医学臨床上筋ジストロフィーを呈する動物に対して、病態解明の糸口を示すものと思われた。\n","subitem_description_type":"Abstract"}]},"item_10006_dissertation_number_12":{"attribute_name":"学位授与番号","attribute_value_mlt":[{"subitem_dissertationnumber":"甲第 108号"}]},"item_10006_version_type_18":{"attribute_name":"著者版フラグ","attribute_value_mlt":[{"subitem_version_resource":"http://purl.org/coar/version/c_ab4af688f83e57aa","subitem_version_type":"AM"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"弓削田, 直子"}],"nameIdentifiers":[{"nameIdentifier":"16156","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2013-02-05"}],"displaytype":"detail","filename":"diss_dv_kou0108.pdf","filesize":[{"value":"37.8 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"diss_dv_kou0108","url":"https://az.repo.nii.ac.jp/record/3153/files/diss_dv_kou0108.pdf"},"version_id":"d23a7aec-fc6b-4194-b81a-3b7b1f7daa98"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2014-08-19"}],"displaytype":"detail","filename":"diss_dv_kou0108_jab&rev.pdf","filesize":[{"value":"414.7 kB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"diss_dv_kou0108_jab&rev","url":"https://az.repo.nii.ac.jp/record/3153/files/diss_dv_kou0108_jab&rev.pdf"},"version_id":"09bd3335-edc5-42f7-98c4-bfc41ba731ef"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"jpn"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"Canine X-linked muscular dystrophy in Japan(CXMD_J) における心機能障害の病態に関する研究","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Canine X-linked muscular dystrophy in Japan(CXMD_J) における心機能障害の病態に関する研究"},{"subitem_title":"Characterization of cardiomyopathy in canine X-linked muscular dystrophy in Japan","subitem_title_language":"en"}]},"item_type_id":"10006","owner":"4","path":["391"],"pubdate":{"attribute_name":"公開日","attribute_value":"2013-01-16"},"publish_date":"2013-01-16","publish_status":"0","recid":"3153","relation_version_is_last":true,"title":["Canine X-linked muscular dystrophy in Japan(CXMD_J) における心機能障害の病態に関する研究"],"weko_creator_id":"4","weko_shared_id":4},"updated":"2023-06-19T08:14:55.504709+00:00"}