ウシの心臓原発腫瘍の病理学的研究 : 新分類名「牛の心臓血管筋腫」の提唱

動物においてもヒトにおいても自然発生性の心臓原発腫瘍は少ない。ウシにおいてもその発生率が低いため，ウシの心臓腫瘍に関する報告の多くは症例報告あるいはウシに関する他の目的の研究における偶発病変の簡単な記載にとどまり，光顕的，電顕的あるいは免疫組織化学的に詳細に検討した報告はない。日本では，食肉衛生検査所においてときおり，心臓腫瘍が見出されており，これらの一部を除いては，様々な診断名で議論されて来た。しかしながら，この診断名の確定されていない心臓腫瘍の症例数が増すに従い，これらの腫瘍に共通する肉眼的・組織学所見が見出され，同一の腫瘍と見做されるようになった(仮称;ウシの心臓内腫瘍/Bovine intracardiac tumor，以下BICTと略す)。　本研究の目的は，牛の心臓原発腫瘍を発生状況，光顕的，電顕的並びに免疫組織化学的に検討し，BICTの本態と起源を明らかにすることである。　本研究には18年間に各地の食肉衛生検査所で収集された41例のウシの心臓腫瘍が提供された。発生部位は，心外膜に発生したもの3例と心筋内あるいは心内膜に発生したもの38例で，左心室に生じたものが25例(うち心外膜1例，心筋内1例，心内膜23例)，右心室に生じたもの13例(うち心内膜13例)，左心耳に生じたもの1例(心内膜)及び右心房に生じたもの1例(心外膜)であった。これらは組織学的に7種類に分類された。その内訳は，BICT33例，平滑筋肉腫3例，平滑筋腫1例，血管平滑筋腫1例，神経線維腫1例、悪性心膜中皮腫及び悪性大動派小体腫1例であった。BICTは，採取されたウシの心臓腫瘍の80.5%を占め，ウシでは最も出現頻度の高い心臓腫瘍と考えられた。BICTの発生頻度は，4ヵ所の食肉衛生検査所における調査によると，10万頭あたり0.59から1.75頭で，平均1.22頭であった。担腫瘍動物の品種は33例のうち25例(83.3%)がホルスタイン種で，5例が黒毛和種であった。また，33例中20例(66.7%)が去勢雄，10例が雌で，年齢は，18から84カ月齢，平均33.2ヵ月齢であった。BICT33例中29例(87.9%)が孤在性の腫瘍で，21例(63.6%)が左心室に発生した。腫瘍塊は乳頭筋を含む弁複合体にのみ発生し，いずれも心内性であった。なお，両側の心室に発生した例はなかった。大きさは米粒大から直径10cmで，転移は認められなかった。　病理組織学的に，BICTにはときに観兵式状配列を示す細胞束を形成する紡錐形細胞の増殖部(pattern A)と海綿状血管腫に類似する扁平な細胞で内張りされる多くの血管あるいは血管腔よりなる(pattern B)の2つの異なる組織像が認められた。いずれのパターンも，多形性で，好酸性の細胞質と周囲に基底膜様構造をもつ大型細胞が認められ，pattern Aの部分では散在あるいは集簇していた。この細胞はときに細胞質突起を伸ばして，他の細胞と連絡し，細胞間にスリット状の間隙あるいは明瞭は管腔を持つ管状物(tube)を形成していた。これらのtubeは吻合あるいは分岐して，細胞性網工をつくり，部位によっては明らかな血管路を形成しており，これらは多細胞性血管形成と見做された。また，散在する大型細胞はしばしば1個あるいは複数の空胞をもち，ときにその空胞内に赤血球が存在し，これは単細胞性血管形成と見做された。pattern Bにみられた多くの血管腔は扁平な細胞によって内張りされ，それらの中に大型で，異型性を示し，クロマチンに富む核を持つ大型細胞が観察された。また，腫瘍組織には，pattern A及びBの組織以外に平滑筋束や粘液腫性の部分がみられた。　これらの共通する構成要素について詳細に検討を行った。免疫組織化学的には，pattern Aに存在する紡錐形細胞のほとんどにactinおよびsmooth muscle actinがみられたが，desminはみられなかった。平滑筋束では，今回の検索に使用したすべての筋系マーカー(actin，smooth muscle actin，desmin)が陽性であった。他方，平滑筋束を除く腫瘍組織のすべての成分が，vimentin陽性であった。pattern AとBにみられた大型細胞の細胞質には瀰漫性にtypeIV collagenが証明され，血管内皮のマーカーであるvon Willebrand factorもときに証明され。血管腔を内張りする扁平細胞にもvon Willebrand factorが証明されるものもあった。大型細胞周囲の基底膜様構造，tubeあるいは血管腔の基底膜は，type IV collagen陽性であった。　電顕的に，BICTの主成分である紡錐形細胞は、円形から類円形の核をもち，細胞質には様々な量の中間径フィラメントを含み，細胞周囲に基底膜を伴っていた。水腫性の部分に散在する大型細胞には，多数の細胞小器官と細胞周囲に塊状の基底膜様物質および自由縁に微絨毛がみられた。tubeを形成する細胞にはときに飲小胞と細胞間接着装置を形成する指状嵌合が認められた。担空胞細胞は、少数の微絨毛をもつ通常のcytoplasmic luminaと呼ばれる細胞質内管腔，中間径フィラメントおよび基底膜をもっていた。大型細胞により内張りされるtube，0.3から1.9μmで，様々な厚さの基底膜によって囲まれていた。基底膜は概ね連続していたが，大型細胞の細胞質突起の挿入により，突然菲薄化したり，途切れたりしていた。基底膜の多層化あるいは塊状化は，循環血のみられる血管路(canalized channel)で目立った。pattern Bの血管腔を内張りする扁平細胞には少数の微絨毛と辺縁ひだ様の構造が，また，その肥大した細胞には多くの微絨毛と細胞小器官が認められた。　以上の検索結果は，BICTの主成分である紡錐形細胞が，平滑筋へ分化する能力あるいは平滑筋の性格を有する細胞であり，大型細胞は血管内皮としての特徴を有し，単細胞性と多細胞性の血管形成によって血管路をつくる能力をもつ細胞であることを示唆していた。このことから，BICTは血管筋腫の範疇に入るものと考えられた。しかし，BICTでは，1つの腫瘍の中に紡錐形細胞の平滑筋への様々な分化像と，血管内皮の性格を育する大型細胞が様々な血管形成の形態と段階をとって毛細血管を盛んに形成する所見が認められ，ヒトの血管筋腫とは異なっていた。さらに，BICTと同様の組織像を持つ腫瘍は，ヒトおよびウシ以外の動物で報告がなく，ウシにおいても心臓にのみ発生することから，BICTに対して，新分類名"牛の心臓血管筋腫Bovine cardiac angiomyoma"(以下BCAMと略記する)を付することを提唱したい。　BCAMにみられる血管形成は，血管原性腫瘍にみられる像よりむしろ創傷修復の過程にみられるものに類似しており，細胞密度の低い部分は心臓の線維三角の幼若組織あるいは弁のspongiosaに類似していた。また，平滑筋束は紡錐形細胞の最終分化像とも見做された。このようなBCAMの組織学的な異質性，発生部位，年齢などの要因から，著者は平滑筋への分化能と血管形成能をもつ心内膜床のような胎生期の組織，あるいは心内膜下の多潜能をもつ間葉系の細胞を起源とする過誤腫的な腫瘍と結論する。腫瘍組織内の大型細胞の細胞質内に大量のtype IV collagenが証明されたが，これは新しい知見でBCAMの診断上重要な腫瘍マーカーとなるであろう。Spontaneous primary cardiac tumors are uncommon in animals and man. They are rare in bovine species. Because of this low incidence, most documents on bovine cardiac tumors are case reports and brief descriptions of incidental findings. There has been no report dealing with bovine cardiac tumors by light and electron microscopy and immunohistochemistry. In Japan, veterinarians working as meat inspectors occasionally have encountered such cases. Several different diagnoses were made for these tumors because of the complicated morphlogy. Most of them seemed to belong to one group that was tentatively named "bovine intracardiac tumor" (BICT). The purpose of this study is to describe the profile, light and electron microscopic findings and immunohistochemical features of bovine primary cardiac tumors and to clarify the controversial origin of BICT. Forty- one neoplasms in the bovine heart were collected and supplied by meat inspectors during the last18 years. Among these, 38 neoplasms were located in the intracardiac portion including endocardium and myocardium; 3 in the pericardial portion; 25 in the left ventricle(1 pericardial, 1 intramural and 1 endocardial), 13 in the right ventricle(13 endocardial), 1 in left autial auricle(endocardial) and 1 in right atrium(pericardial). These 41 cases included 7 types of tumors; 33 BICT, 3 leiomyosarcoma, 1 leiomyoma, 1 vascular leiomyoma, 1 neurofibroma, 1 malignant mesothelioma and 1 malignant chemodectoma. BICT comprised 80.5% of bovine cardiac tumors in this series, suggesting the commonest primary cardiac tumor in cattle. The occurrence rate of BICT was between 0.59 and 1.75 per 100,000 slaughtered cattle. The average was 1.22 per 100,000 slaughtered cattle among 4 meat inspection fascilities. Twenty-five cases (83.3%) out of 33 occurred in Holstein-Friesian cattle and 5 cases in Japanese Black. Twenty cases (66.7%) out of 33 were seen in castrated male and 10 cases in female. Age of affected animals varied from 18 to 84 month-old and the average was 33.2 month-old. Twenty-nine cases (87.9%) were solitary and 21 cases were (63.6%) located in the left ventricle, involving papillary muscles and valves. None involved both ventricles. Size of BICT ranged from a rice grain to a large spherical mass measuring about 10 cm in diameter, while no metastasis was seen. Light microscopy revealed two different patterns of tissues in BICT: 1) spindle cell proliferation forming the cellular fascicles with some palisading areas (pattern A) and 2) numerous blood vessels or spaces lined with flattened cells resembling to cavernous hemangioma (pattern B). Large cells were seen in both patterns of areas. Pleomorphic large cells having eosinophlic cytoplasm surrounded by basement membrane (BM)-like substance were scattered and/or clustered in pattern A areas. Extended cytoplasmic processes of large cells were in contact with each other, forming tubes with slit-like and/or conspicuous lumen. Such tubes showed bifurcation and anastomosis to form cellular networks, gradually developing into canalized vascular channels [so-called multi-cellular angiogenesis]. Large cells [physaliferous cells] frequently had single or multiple vacuolar spaces including red blood cells compared to single cell angiogenesis. Many blood spaces were lined by flattened endothelial cells and sometimes plump endothelial cells which had large, bizarre and hyperchromatic nuclei. Smooth muscle bundles and myxomatous areas were present in the tumor tissue. Immunohistochemistry revealed that the majority of spindle cells and the major component of pattern A areas were positive for actin and smooth muscle actin, but negative for desmin. Smooth muscle bundles were stained for all muscular markers employed in the present study. All components of tumor tissue located apart from the apparent smooth muscle bundles were stained positively for vimentin. Cytoplasms of large cells in both pattern A and B areas were sometimes stained positively for von Willebrand factor. Some flattened lining cells of blood spaces were also positive for von Willebrand factor. BM-like structures around large cells, cellular tubes and vasculer spaces in pattern B were positive for type IV collagen. Type IV collagen stained diffusely in the cytoplasm of large cells were sparsely distributed in both patterns. Ultrastructural studies using formalin-fixed materials proved some important features of this tumor. Predominating spindle cells had oval to irregular-shaped nucleus, various amounts of intermediate filaments and BM. Large cells in myxomatous area had a number of organelles, massive BM-like substance at the periphery and microvilli on the free margin. Cells forming tubes often exhibited pinocytic vesicles and interdigitation to form junctional complexes. Physaliferous cells had intracytoplasmic lumens with a few microvilli, intermediate filaments and BM. Tubes lined with large cells were surrounded by BM varying in thickness between 0.3 to 1.9 μm. BM ran along the tubes, but often suddenly became thinning or ruptured due to the insertion of cytoplasmic processes of large cells. Degradation of BM was scattered in the canalized vascular channels in which lining cells showed polyptychial or massive arrangement. Flattened lining cells had a few microvilli, marginal fold- like structure and interdigitation in pattern B area. Plump lining cells had numerous microvilli and organelles. These findings suggest that the spindle cells as major component of BICT are immature mesenchymal cells having a capability to differentiate toward smooth muscle cells and large cells are endothelial cells having capabilities to form vascular canals by single cell and multicellular angiogenesis. Therefore, BICT will be included in the category of angiomyoma. However, there were some differences between BICT and angiomyoma in man. Spindle cells and large cells that were two important components in BICT retained the abilities to differentiate toward smooth muscle and vascular endothelium with varying degree. Large cells formed capillary vessels. There are no reports on tumors having a morphology similar to those of BICT in man and animals except for bovines. In addition, BICT was observed only in the heart. The author proposed a new classification "bovine cardiac angiomyoma (BCAM)" to BICT. BCAM mimicked the angiogenesis in the wound healing rather than that in the angiogenic tumors. Low cellularity area resembled the primitive tissue and cells seen in fibrous triangle and spongiosa of valve. Smooth muscular bundles seen in the tumor tissue might be the cluster of differentiated spindle cells. From histological heterogeneity, sites of origin and age factors described above, the author concluded that BCAM had a hamartomatous nature originated from pluripotential mesenchymal cells having capabilities to differentiate smooth muscles and to form vascular structures in the subendocardium or embryonic tissue as endocardial cushion. Abundant type IV collagen was present in the cytoplasm of large cells. This new finding will be an important tumor marker for diagnosing BCAM.博士(獣医学)麻布大

Observation and its Application of the Helicobacter by the Variable Pressure Scanning Electoron Microscope.

Hitachi High-Technologies Co.Medical Incorporated Association of Ishiyama ENT Clinic麻布大学Scedule:17-18 March 2003, Vemue: Kanazawa, Japan, Kanazawa Citymonde Hotel, Project Leader : Hayakawa, Kazuichi, Symposium Secretariat: XO kamata, Naoto, Edited by:Kamata, Naoto

カエルのツボカビ症の疫学的および病理学的研究

我々は, 2006年12月にアジア初のツボカビ症を発見した。これを受けて, カエルツボカビの日本在来種へのリスク評価のための研究を行った。その結果, 1) カエルツボカビ培養株の樹立に成功した。2) 野生下両生類の不審死, 大量死事例35事例72匹を検索し, 野生下では, まだ, ツボカビ症が発生してないことを確認した。3) 飼育下両生類で15箇所9種94匹にツボカビ症の流行を確認した。4) 在来種20種にカエルツボカビを感染させたところ, ヌマガエル, コガタハナサキガエル, ヤエヤマハラブチガエルがツボカビ症を発症し死亡した。以上のことから, 外来種両生類由来カエルツボカビは, 一部の在来種に悪影響を及ぼすことが明らかにされた。よって, 野外での拡散防止に努める必要がある。We confirmed the presence of chytrid fungus (Batrochochitrium dendrobatedis) for the first time in Japan in December, 2006. We underwent this and performed study for risk evaluation to Japanese native amphibians of Batrachochytrium dendrobatidis (Bd). As a result, 1) We succeeded in the establishment of Bd culture. 2) We have begun investigating the cause of mass deaths or unexplained death among wild native frogs. Of 35 episodes (72 individuals) examined so far, not one case of chytrid fungal infection has been identified. 3) Fifteen outbreaks have so far been identified involving 94 frogs in 9 species in captive and exotic amphibians. 4) Japanese native amphibians do show susceptibility to chytrid fungus. Three species (Fejervarya limnocharis, Rana (Eburana) utsunomiyaorum and Rana psaltis) of native frog are sensitive to the chytrid fungus, and die if infected experimentally with the C type. Based upon the foregoing, it was made clear that Bd which divided from exotic species amphibian gave bad influence to some native amphibian. Therefore, we have to try for nonproliferation in the outdoors of Bd

「動物の手と足：その形態と機能」展の記録

An exhibition entitled as “Hands and legs of mammals: the morphology and variations” was held at Azabu University from June to September, 2010. Bones were chosen from many specimens preserved at the specimen store at Azabu University. At the introduction corner, a cat specimen was exhibited in order to explain the principle of mammal body morphology. At the “hindleg corner”, hindlegs of six terrestrial mammals were exhibited. The visitors could compare the “lifting heels” and simplification of the legs in “running” mammals. At the “foreleg corner”, forelegs of a dolphin and a Japanese macaque, whole body of a bat, a flying squirrel, and a mole were exhibited. This corner showed how the mammal forelegs are modified according to the differences in life styles of the animals. At the “femur corner”, femurs of six species of terrestrial mammals were exhibited. This corner told the femurs of larger mammals are more robust than those of smaller mammals, which is explained by physical reasons. At the last corner, forelegs of a giraffe, an elephant, and a horse were exhibited to emphasize the differences of the size and shape as “long”, “gigantic”, and “simple” bones. All the specimens were arranged on boards of deep blue backgrounds which are contrastive to whitish bones, and Chinese kanji letters to symbolize the functions of the bones were laid out

第9回麻布大学学術展示「動物の目：視る器官を学ぶ」展の記録

視覚を司る器官である眼を動物学的視点から解説するとともに，おもに白内障について臨床的立場から説明する展示をおこなった。展示タイトルとしては学外者にもなじみやすいように「目」を用いた。眼の構造をカメラと比較して説明した。視野と，その機能を視界の広さの違う動物を対比させることで解説した。頭部の大きさに対する眼球の大きさの違いとその生物学的意義を解説した。眼疾病について解説した。展示物としてはウシの眼の液浸標本，数種の哺乳類，鳥類の頭骨，それらのアクリル板を設置して立体視の範囲をわかりやすく示した展示物，眼底カメラなどを示した。Animal eyes as the organ of sight were exhibited in terms of zoology as well as treatments of eye diseases. The structure of eyes was explained using comparison with cameras. Relative size of eyes of different mammals and birds and the significance of it was explained with specimens. The degree of overlap of two eyes of different animals was shown. Dr. N. Kanemaki’s insights into the management of eye diseases were introduced

Leptospirosis in Squirrels Imported from United States to Japan

We diagnosed leptospirosis in 2 patients exposed to southern flying squirrels imported from the United States to Japan. Patients worked with exotic animals in their company. Leptospira isolates from 1 patient and 5 of 10 squirrels at the company were genetically and serologically identical and were identified as Leptospira kirschneri

Exotic Small Mammals as Potential Reservoirs of Zoonotic Bartonella spp.

To evaluate the risk for emerging human infections caused by zoonotic Bartonella spp. from exotic small mammals, we investigated the prevalence of Bartonella spp. in 546 small mammals (28 species) that had been imported into Japan as pets from Asia, North America, Europe, and the Middle and Near East. We obtained 407 Bartonella isolates and characterized them by molecular phylogenetic analysis of the citrate synthase gene, gltA. The animals examined carried 4 zoonotic Bartonella spp. that cause human endocarditis and neuroretinitis and 6 novel Bartonella spp. at a high prevalence (26.0%, 142/546). We conclude that exotic small mammals potentially serve as reservoirs of several zoonotic Bartonella spp

Genetic Characterization of Coronaviruses from Domestic Ferrets, Japan

We detected ferret coronaviruses in 44 (55.7%) of 79 pet ferrets tested in Japan and classified the viruses into 2 genotypes on the basis of genotype-specific PCR. Our results show that 2 ferret coronaviruses that cause feline infectious peritonitis–like disease and epizootic catarrhal enteritis are enzootic among ferrets in Japan

チーター（Acinonyx jubatus）における半規管の配置と直交性について

The purpose of this study was to clarify the spatial orientation of the semicircular canals in the cheetah (Acinonyx jubatus) using computed tomography (CT). CT scan was performed on the skull of a cheetah. Scanning data were reconstructed into the cross-sectional images, and then the landmark coordinates were determined to define the planes of the semicircular canals and the cross-sections of the skull. In the cheetah, the lateral semicircular canal was parallel to the base of the skull. The angles between the anterior and posterior semicircular canals was lager than 90 degrees, and each canal showed the similar angle with the sagittal cross-section of the skull, although these planar directions were different. One limitation of this study is that here we provided only one specimen, and thus the present results need to be confirmed by examining a larger number of cases in future studies. However, the method outlined in this study provided quantitative descriptions of orientations and orthogonalities of the semicircular canals of the cheetah. This is potentially useful for indentifying the morphological features of the semicircular canals in felids