ヌードラットにおけるボルナ病ウイルス感染

1. 実験1および2においてCRP3株感染ラットは発症せず，CRNP5株は全例発症し，観察期間中に全例が死亡または重篤な症状(スコア3)となった。2. CRP3株およびCRNP5株感染ラットの脳では全例で，海馬病変を主体とする非炎症性の脳病変(脳症)が認められた。3. CRNP5株感染ラットでは大脳皮質菲薄化を伴う脳室拡張(hydrocephalus ex vacuo)が認められた。4. CRP3株とCRNP5株感染ラットの脳では神経細胞を主体とするBDV陽性所見が存在していた。5. 偽接種群のヌードラットは実験1及び2において臨床症状が認められず組織学的に正常であった。6. 脳を大脳皮質，脳幹部及び小脳に分割してウイルス力価を測定したところ，BDV-CRP3株感染群に比べBDV-CRNP5株感染群では脳幹部のウイルス力価が高かった。7. ボルナ病ウイルス感染ではT細胞性免疫応答を介さない発症機序があり，発症程度及び病変はウイルス株により異なることが示唆された。Fifty-three immunodeficient nude rats (four weeks old) were used in this experiment. The rats were inoculated with either CRNP5 strain or CRP3 strain of Borna disease virus (BDV) intracranially and were observed for seven weeks (experiment 1) or eight weeks (experiment 2). In experiment 1, if the inoculated rats showed clinical symptoms and developed severe Borna disease (BD) (score 3). the rats were killed and histological studies and virus titration of the brain samples were performed. If the rats did not show severe clinical symptoms, the rats were killed and histological studies and virus titration of the brain samples were performed at the end of the experiment. In experiment 2, the inoculated rats were killed chronologically in the second, fourth or eighth week after inoculation or when the inoculated rats showed clinical symptoms and developed severe BD (score 3).All CRNP5 inoculated rats developed neurological signs, suspected of indicating BD between 24 and 36 days after virus inoculation. Conversely, CRP3 inoculated rats did not develop any neurological signs during the course of either experiment.Histopathologically and immunohistochemically there were three common findings in both strains of BDV inoculated rats: 1) degeneration. necrosis and apoptosis of nerve cells and focal calcifications without inflammation, 2) gliosis, 3) BDV antigen positive reactions in the nerve cells and astrocytes. In CRP3 inoculated rats, atrophy of the dentate gyrus associated with degeneration, necrosis and apoptosis of the neurons of the granular layers of the dentate gyrus was the significant finding. In CRNP5 inoculated rats. there were three major changes: 1 ) hydrocephalus ex vacuo, 2) disarrangements of the nerve cells in the hippocampal CA3 region and degeneration. necrosis and apoptosis of the nerve cells of the granular layers of the dentate gyrus. In the brain samples of all inoculated nude rats. the virus was recovered and the titer of the virus was higher than other parts of the brain.In the previous athymic rats infections of BDV. the virus-specific nucleic acid and infectious virus were found in the inoculated rats. but there were no signs of BD and histopathological lesions

ULTRASTRUCTURAL STUDIES ON MUSCULAR ATROPHY IN MAREK'S DISEASE : I. DENERVATION ATROPHY IN CHICKEN SKELETAL MUSCLE A LIGHT AND ELECTRON MICROSCOPIC STUDY

When denervation was performed by nerve-cutting and nerve-crushing in chickens, three phases could be observed morphologically. The first phase was characterized by foregoing degenerative changes of the neuro-muscular junctions (axon terminals), followed by atrophic changes of the muscle fibers. The second phase was characterized by irregular arrangement of the myofilaments in atrophic muscle fibers and appearance of regenerative muscular changes by 20 days after denervation. By this time, no morphological differences could be discerned between the nerve-cut and the nerve-crushed specimens. The third phase was characterized by distinct morphological differences between the nerve-cut and the nerve-crushed specimens. This phase began from the 30-day after denervation. These differences became more marked day by day. On the 60- day after denervation, almost all muscle fibers showed normal structures of the myofibrils in the nerve-crushed specimens, whereas, muscle fibers were still atrophic in the nerve-cut specimens

ULTRASTRUCTURAL : STUDIES ON MUSCULAR ATROPHY IN MAREK'S DISEASE II. MUSCULAR LESIONS IN SPONTANEOUS CASES

The skeletal muscles of 14 spontaneous cases of MD were investigated by light and electron microscopy. The muscular lesions of MD were classified into 3 categories : Category I-myoatrophic changes, Category II-myodegenerative changes, and Category III-neoplastic proliferative changes. The present investigation was focused on the Category I lesions. Light microscopically, the atrophic fibers were sparsely distributed between the normal sized muscle fibers in mild cases. In the advanced stage, there were often clear-cut groups of atrophic fibers, and finally, groups of variable numbers of atrophic fibers were extensively seen. Electron microscopically, irregularity of the fiber outline was commonly seen. The process of myofibrillary breakdown was conspicuous and seemed to start with disruption of the regular alignment of the myofilaments and streaming of Z-bands. The intermyofibrillar spaces were enlarged. The central nuclei with irregular shapes were often arranged in a row and increased in number. Targetoid fibers, honeycomb-like structures, and satellite cell activity were also observed. These findings were similar to those seen in experimental denervation. Therefore, the authors attributed these atrophic changes to neurogenic origin

PATHOMORPHOLOGICAL OBSERVATI0NS ON EPIDERMAL PAPILLOMA OF FLATFISH (LIOPSETTA OBSCURA)

Morphological investigation was carried out on 10 flatfishes (Liopsetta obscura) which were collected in Odaito, the eastern part of Hokkaido, and they were diagnosed as epidermal papilloma. Electron microscopically, the characteristics of so-called "X-cells" were clarified. They were considered as free cells which were completely different from epidermal cells and general inflammatory cells. Aggregation of fine hollow particles (ca. 30 nm) in the nucleus and particles enclosed by a double membrane with a central core in the cytoplasm were found in the X-cells. Numerous virus-like particles (ca. 100 nm) were found in the nuclei of the degenerative epithelial cells of the epidermis. Etiological relationship between epidermal papilloma and virus-like particles are not yet unknown and further investigations are needed

Evaluation of weekly bathing in allergic dogs with methicillin-resistant Staphylococcal colonization

We evaluated the efficacy of weekly bathing in reducing methicillin-resistant Staphylococcus (MRS) colonization in canine allergic dermatitis in a pilot clinical trial. Six dogs with allergic dermatitis controlled by prescription medications were treated with weekly bathing for 1 month. The Canine Atopic Dermatitis Extent and Severity Index version 3 (CADESI-03) and pruritus scores and frequency of mecA-positive Staphylococcus spp. isolated from three body sites between weeks 0 and 4 were compared. There was no significant difference in CADESI-03 scores with bathing, whereas the pruritus scores were significantly reduced (p < 0.05). Furthermore, MRS frequency was decreased in four of the six dogs (p < 0.05). In conclusion, weekly bathing should be considered for reducing MRS colonization in canine allergic dermatitis