Neuroendocrine cells are of the peptide and amine secreting cells and because of endodermal origin, exist in respiratory and gastrointestinal system. The report confirms the presence of a tumor using immunohistochemical methods. A hepatic mass was detected in a 10-year-old male mixed–breed dog which was referred with clinical history of frequent vomiting, anorexia, lethargy and syncope. Biochemical and hematological abnormalities included elevation of ALT and AST levels, leukocytosis and anemia. Radiographically the large hepatic mass and multifocal metastatic nodular areas in the other organs were observed. At necropsy the liver had a multilobulated firm mass involving whole caudate lobe of the liver. On the cut section, the tumor was grey sanguineous with hemorrhagic surface and numerous necrotic foci. Microscopically, there were unencapsulated, highly cellular neoplastic proliferations with few hemorrhagic foci in the liver that had a trabecular pattern to Rosette formation which were separated by a fibrovascularstroma. The neoplastic cells were round to oval, with granular eosinophilic cytoplasm and hyperchromatic nuclei. Metastases were observed in lungs, kidneys, mesenteric lymph nodes and even in the arteries of the tunica albuginae of the testes. Immunohistochemically, neoplastic cells were immunoreactive for NSE and S100 protein. They were negative for CEA, Chromogranine A, CD34, AE1/AE3, CK20 and Hepatic Antigen (HA). Negative CEA, CK20, CD34 and HA disproved the probability for collangiocarcinoma, metastatic carcinoma, hematopoietic and vascular origin and hepatocellular carcinoma of this tumor respectively. Immunohistochemical demonstration of NSE and S100 protein supported the diagnosis of the Carcinoid like. However, negative reaction for Chromogranine A does not disprove neuroendocrine carcinoma diagnosis.

Melanomas are the most common oral malignancy in dogs. Cell proliferation and connexin expression has been shown to differ in canine melanotic and amelanotic oral melanomas. This study aimed to analyze the c-Kit protein expression in melanotic and amelanotic melanomas from canine buccal cavity. A total of 34 canine buccal melanomas (19 melanotic and 15 amelanotic).were collected. The amelanotic melanomas presented faster evolution and higher incidence of metastasis than melanotic tumors. A significantly higher number of c-Kit positive cells were observed in amelanotic neoplasms. In addition, the intensity of c-Kit immunolabeling was predominantly stronger in amelanotic melanomas. These results confirm a potential role for c-Kit in canine oral melanomas with clear differences in expression patterns between the two histological types of tumor, melanotic and amelanotic. This study highlights the importance of a detailed study of c-Kit mutations in canine oral melanomas to better understand the molecular mechanisms implicated in the development of this disease.

OBJECTIVE To characterize the expression of monocarboxylate transporters (MCTs) 1 and 4 and the ancillary protein CD147 in the intestinal tract of healthy equids and determine the cellular location of CD147 in the intestinal epithelium. ANIMALS 12 healthy horses and ponies slaughtered for meat production or euthanized for reasons unrelated to gastrointestinal tract disease. PROCEDURES The entire gastrointestinal tract was removed from each equid within 45 minutes after slaughter or euthanasia. Tissue samples were obtained from the antimesenteric side of the duodenum, jejunum, ileum, middle part of the cecum, sternal flexure of the ventral colon, pelvic flexure, sternal flexure of the dorsal colon, and descending colon (small colon). Expressions of MCT1, MCT4, and the ancillary protein CD147 were examined in tissue samples from each of the 8 intestinal locations by means of quantitative PCR assay, immunoblotting, and immunohistochemical analyses. RESULTS Expression of MCT1 was most abundant in the cecum and colonic sites, whereas expression of MCT4 was predominantly in the proximal section of the intestine (small intestinal sites and cecum). Immunohistochemical analysis revealed that MCT1 and CD147 were present in the membranes of enterocytes (in crypts and villi). CONCLUSIONS AND CLINICAL RELEVANCE The anatomic distribution of MCT1 and MCT4 in the equine intestinal tract determined in this study together with the previous knowledge of the sites of substrate absorption indicated that MCT1 might predominantly contribute to the uptake of short-chain fatty acids in the large intestine and MCT4 might predominantly contribute to the uptake of lactate in the small intestine.

The objective of this study was to develop a murine retinal/choroidal/scleral explant culture system to facilitate the intravitreous delivery of vectors. Posterior segment explants from adult mice of 2 different age groups (4 wk and 15 wk) were cultured in serum-free medium for variable time periods. Tissue viability was assessed by gross morphology, cell survival quantification, activated caspase-3 expression, and immunohistochemistry. To model ocular gene therapy, explants were exposed to varying transducing units of a lentiviral vector expressing the gene for green fluorescent protein for 48 h. Explant retinal cells remained viable for approximately 1 wk, although the ganglion cell layer developed apoptosis between 4 and 7 d. Following vector infusion into the posterior segment cups, viral transduction was noted in multiple retinal layers in both age groups. An age of donor mouse influence was noted and older mice did not transduce as well as younger mice. This explant offers an easily managed posterior segment ocular culture with minimum disturbance of the tissue, and may be useful for investigating methods of enhancing retinal gene therapy under controlled conditions.

Circulating monocytes and tissue macrophages were suggested to be susceptible to avian reovirus (ARV) infection. To determine if ARV infects and replicates in mononuclear phagocytes (KUL01-positive cells), we infected 3-day-old specific-pathogen-free chickens with ARV strain 2408 by inoculation of the left footpad. The left footpads and spleens were collected for analysis at 1.5 and 2.5 d after inoculation. Replication of ARV in the footpad and spleen was demonstrated by detection of the viral protein σNS using immunohistochemical testing and viral S1 RNA expression by real-time quantitative polymerase chain reaction (qPCR). Furthermore, immunofluorescent double-staining assay of cytocentrifuged cells and cryosections of the footpad and spleen for the viral protein σNS and the surface marker recognized by monoclonal antibody (MAb) KUL01 indicated that KUL01-positive cells costained with MAb H1E1, which recognizes ARV protein σNS. In addition, more ARV S1 RNA was measured by qPCR in the KUL01-positive cell samples prepared from the footpad or spleen 1.5 d after inoculation compared with non-KUL01-positive cell samples. The amounts of ARV S1 RNA in the spleen were significantly lower (P < 0.05) than the amounts in the footpad 1.5 d after inoculation. The results suggest that ARV infects mononuclear phagocytes and then replicates within these cells before migrating to the spleen, where it infects and replicates in KUL01-positive cells.

OBJECTIVE To characterize epithelial cells of the small intestine and colon in horses without clinical gastrointestinal abnormalities with an emphasis on the stem cell niche constituents. SAMPLE Mucosal biopsy specimens from small and large intestines obtained from 12 horses euthanized for reasons unrelated to gastrointestinal disease or systemic disease. PROCEDURES Intestinal biopsy specimens were collected by sharp dissection immediately following euthanasia. Specimens were prepared for immunohistochemical, immunofluorescence, and transmission electron microscopic imaging to detect and characterize each epithelial cell type. Antibodies against protein biomarkers for cellular identification were selected on the basis of expression in other mammalian species. RESULTS Intestinal epithelial cell types were identified by means of immunostaining and morphological characterization with transmission electron microscopy. Some differences in biomarker expression and antibody cross-reactivity were identified in equine tissue, compared with other species. However, each known type of mucosal epithelial cell was identified in equine tissue. CONCLUSIONS AND CLINICAL RELEVANCE The methodology used can enhance detection of stem cells and progenitor cells as well as postmitotic cell lineages in equine intestinal tissues. Results may have relevance to regenerative potential of intestinal mucosa and survival in horses with colic.

Mannheimia haemolytica is an important cause of pneumonia in feedlot cattle. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a redox-sensitive transcription factor responsible for the induction of antioxidant enzymes, such as heme oxygenase 1 (HO-1), within the lung. The expression of Nrf2 and HO-1 was immunohistochemically evaluated in 4 calves 24 h after experimental infection with M. haemolytica. Calves receiving normal saline served as controls. In the infected lungs, cytoplasmic Nrf2 expression was high in macrophages and bronchioles and low in alveolar epithelium, whereas nuclear expression was high in endothelial cells, macrophages, and bronchioles and lowest in alveolar epithelium. Normal lung samples displayed only faint Nrf2 cytoplasmic staining within bronchiolar epithelium. Expression of HO-1 was detected within the cytoplasm of macrophages and bronchiolar epithelial cells in all infected lung samples, whereas normal lungs displayed only weak cytoplasmic staining in bronchiolar epithelial cells. These findings suggest that bronchiolar epithelial cells and macrophages up-regulate Nrf2 expression early in the course of infection, which results in increased expression of HO-1 within these cells.