Histopathologic Evolution of Cardiomyopathy in a Canine Model of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a recessive X-linked disorder characterized for mutation in dystrophin gene and manifested by progressive degeneration and necrosis of skeletal and cardiac muscle with replacement leading to generalized muscular weakness and atrophy. The dog Golden Retriever Muscular Dystrophy (GRMD) is the best experimental model for DMD, with genotypic and phenotypic manifestations closely of human disease. Similar to patients with DMD, heart failure is a major cause of death in GRMD animals. The objective of this study was to evaluate the pathological progression of myocardial lesions from GRMD dogs in different ages in order to clarify the pathogenesis of Duchenne´s cardiomyopathy. Fragments of left and right ventricle and interventricular septum, from 18 GRMD dogs between 6 to 51 months were collected, fixed, dehydrated, clarified, and finally embedded in paraffin. Five micrometer thick serial sections were obtained and stained with Hematoxylin-Eosin (HE), Picrosirius red, and Von Kossa. Histological analyses were performed at the light microscopy. Myocardial lesions were observed in all GRMD dogs and the sequence of cardiac lesion classified according to according to the age included: abnormal calcium accumulation, myofibrillar necrosis, proliferation of granulation tissue, endomysial and perimysial fibrosis, and finally myocardial fatty infiltration. Interestingly, several Anitschkow cells, the hallmark of rheumatic carditis, were detected in inflammatory infiltrate present at granulation tissue. Our results demonstrate the sequence of cardiac lesions that determine the cardiomyopathy in Golden Retriever dogs affected by DMD and exhibit, for the first time, the Anitschkow cells in the histological findings of this cardiomyopathy. These results are relevant for to clarify the pathogenesis of cardiomyopathy in dogs and humans affected by DMD

Involvement of organic systems in golden retriever X-linked muscular dystrophy

Duchenne muscular dystrophy is a lethal genetic disease characterized by progressive muscle degeneration that usually had been used the Golden Retriever as a model for studying the disease (GRMD - Golden Retriever Muscular Dystrophy). A total of 16 male dystrophic Golden Retrievers dogs between 5 to 51 months of age were examined in the present study. The animals were classified as dystrophic according to two simultaneous complementary criteria: genotypic analysis and serum creatine kinase levels. The macroscopic abnormalities of the different organs and tissues and histopathological features were described using hematoxylin-eosin. The lesions in the skeletal muscles associated with the digestive problems resulted in cachexia with different intensities in all the dystrophic dogs. Cardiac muscle involvement was found in 87,5% of the GRMD dogs resulting, however, in cardiac failure in only 18,8% of the animals. The musculature of the diaphragm was hypertrophic in all affected animals resulting in progressive respiratory muscle weakness and at later stages in respiratory failure (81,25%). The liver abnormalities found in dystrophic dogs were originated mainly from heart disease and developed progressively. Hyperemia of mucosa and granular material indicated changes in the functioning and emptying of bladder. The germinative lineage cells presented moderate to severe degeneration probably due to degeneration of the scrotum and cremaster muscle which prevented the proper thermo-regulation of the testicle. Our results highlight the fact that there is significant impairment of the cardiac, respiratory and skeletal muscle systems in GRMD dogs since the age of five months. In addition, significant alterations of the gastrointestinal tract, urinary and reproductive systems are indicating the presence of degenerative lesions in the smooth musculature

Myxosporidiosis in intensively-reared Piaractus mesopotamicus: Histopathological diagnosis by means of Ziehl-Neelsen staining

Amostras de diferentes órgãos de Piaractus mesopotamicus mantidos em criação intensiva foram coletadas e processadas mediante as técnicas histológicas usuais para obtenção de cortes que foram corados com hematoxilina-eosina e pelo método de Ziehl-Neelsen. Ao exame em microscopia de luz foi possível identificar mixosporídeos dos gêneros Henneguya sp. e Myxobolus sp. em brânquia e rim de P. mesopotamicus respectivamente. Plasmódios com esporos imaturos de Henneguya sp. foram localizados ao longo das lamelas secundárias e mensurados (comprimento total 30,45±4,84µm e largura 3,52±0,33µm) e no rim esporos de Myxobolus sp. (comprimento total 8,94±0,82µm e largura 5,59±0,39µm). Na análise histopatológica das brânquias observaram-se plasmódios contendo esporos de Henneguya sp., com localização intralamelar e intravascular, em diferentes estágios de desenvolvimento. No rim identificaram-se esporos de Myxobolus sp., na região peritubular e no interstício e glomérulo, circundados por melanomacrófagos. em poucos casos foi registrada hemorragia focal. O uso da coloração de Ziehl-Neelsen permitiu identificar particularidades dos esporos, facilitou sua biometria e classificação em comparação com a hematoxilina-eosina, demonstrando sua utilidade no diagnóstico histopatológico da referida parasitose.Samples of different organs from intensively-reared Piaractus mesopotamicus were collected and processed using routine histological techniques in order to produce thin sections for staining with hematoxylin-eosin and with the Ziehl-Neelsen method. Through examination under an optical microscope, myxosporidians of the genera Henneguya sp. and Myxobolus sp. were identified, respectivelyin the gills and kidneys of P. mesopotamicus. Plasmodia with immature spores of Henneguya sp. were located along the secondary lamellae, with total length of 30.45±4.84µm and width of 3.52±0.33µm. Spores of Myxobolus sp. were located in the kidneys, with total length of 8.94±0.82µm and width of 5.59±0.39µm. Histopathological analysis of the gills showed plasmodia containing spores of Henneguya sp., at intralamellar and intravascular localities, at different stages of development. Spores of Myxobolus sp. were identified in the kidneys, in the peritubular region and in the interstices and glomerulus, surrounded by melanomacrophages. Focal hemorrhage was recorded in a few cases. Ziehl-Neelsen staining allowed to identify particular features of the spores and facilitated biometry and enabled classification in comparison with hematoxylin-eosin, thus demonstrating its usefulness for histopathological diagnosis of the parasitosis.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Acute aerocystitis in Piaractus mesopotamicus: Participation of eicosanoids and pro-inflammatory cytokines

A total of 360 pacus (Piaractus mesopotamicus) were used to study vascular permeability (VP) and inflammatory cell component (CC) in induced aerocystitis in P. mesopotamicus through inoculation of inactivated Aeromonas hydrophila, and the effect of steroidal and nonsteroidal anti-inflammatory drugs. It was observed that after inoculation of A. hydrophila, the maximum VP occurred 180 min post-stimulus (MPS). Pretreatment with anti-inflammatory drugs inhibited VP, and the inhibitory effect of dexamethasone was seen earlier than the effects caused by meloxicam and indomethacin. Inoculation of the bacterium caused a gradual increase in the accumulation of cells, which reached a maximum 24 h post-stimulus (HPS). Pretreatment with dexamethasone, indomethacin and meloxicam reduced the accumulation of lymphocytes, thrombocytes, granulocytes and macrophages. There was no significant difference between the different doses of the drugs tested. The results suggest that eicosanoids and pro-inflammatory cytokines participate in chemical mediation in acute inflammation in pacus. © 2013 Elsevier Ltd