Characterization of an antibody panel for immunohistochemical analysis of canine muscle cells

The immunohistochemical evaluation of selected markers in the left atrium of dogs with end-stage dilated cardiomyopathy and myxomatous mitral valve disease - a preliminary study

Background

Dilated cardiomyopathy (DCM) and myxomatous mitral valve disease (MMVD) are the most common diseases noted in dogs. Although their pathogenesis varies, both include a significant enlargement of the left atrium.

The study was carried out on left atrial specimens obtained from 56 dogs, including those from 34 dogs with clinically diagnosed MMVD, 15 dogs with DCM and 7 dogs without heart disease (control group). Dogs in the MMVD and the DCM groups presented with left atrial enlargement and stage D heart failure. The specimens underwent immunohistochemical examination using desmin, vimentin, periostin and caspase-3 antibodies.

Results

There were alterations in the expression of the studied proteins in the study groups compared to the control group. The changes included: irregularity of desmin cross-striation and desmosomes, a higher amount of vimentin-positive cells, a change in the periostin expression pattern from cytoplasmic to extracellular, and a lower expression of caspase-3. The alterations were more pronounced in the DCM group than in the MMVD group.

Conclusions

During heart failure, the pattern of desmin, vimentin, periostin and caspase-3 expression alters in the left atrium, regardless of the cause. The changes are more pronounced in dogs with DCM than in dogs with MMVD and similar left atrial enlargement, suggesting that volume overload may not be the only cause of myocardial changes in DCM.

A Comparative Review of Canine and Human Rhabdomyosarcoma With Emphasis on Classification and Pathogenesis

Rhabdomyosarcomas are a diverse group of malignant mesenchymal neoplasms exhibiting variable levels of differentiation toward skeletal myocytes. Neoplastic cells may resemble relatively undifferentiated myoblasts, satellite cells, or more differentiated elongated spindle cells and multicellular myotubes. In veterinary medicine, classification into subtypes and variants is based on an outdated system derived from human pathology and is solely based on histologic characteristics. In contrast, classification of human rhabdomyosarcoma is based on histologic, immunohistochemical, and molecular diagnostic techniques, and subclassification has clinical and prognostic relevance. Relevance of tumor subtyping has not been established in veterinary medicine. Recent discoveries of components of the molecular pathogenesis and genomes of human rhabdomyosarcomas have led to new diagnostic techniques and revisions of the human classification system. The current classification system in veterinary medicine is reviewed in light of these changes. Diagnosis of rhabdomyosarcoma using histopathology, electron microscopy, and the clinical aspects of human and canine rhabdomyosarcomas is compared. The clinical features and biologic behavior of canine rhabdomyosarcomas are compared with canine soft tissue sarcomas.

Immunohistochemical Evaluation of GATA-4 in Canine Testicular Tumors

GATA-4 is a transcription factor expressed in Sertoli cells and less commonly in Leydig (interstitial) cells but not germ cells in adult human beings, cattle, pigs, and mice. We examined GATA-4 in 76 formalin-fixed, paraffin-embedded canine testicular tumors, including 21 Sertoli cell tumors (SCT), 28 Leydig (interstitial) cell tumors (LCT), 24 seminomas (GCT), and 3 mixed germ cell sex cord-stromal tumors (MGSCT). Our hypothesis was that immunohistochemistry for GATA-4 could discriminate between germ cell and sex cord-stromal tumors of the canine testis. SCTs (21/21) had strong diffuse nuclear and weak and inconsistent cytoplasmic staining. LCTs (27/28) also had strong diffuse nuclear staining and much weaker and granular cytoplasmic staining. GCTs were negative for this marker. Sex cord-stromal cells of MGSCT were also positive. These results indicate that GATA-4 is mainly expressed in sex cord-stromal tumors and not in germ cell tumors of the canine testis.