Genome-Wide Association Analysis Identifies a Mutation in the Thiamine Transporter 2 (SLC19A3) Gene Associated with Alaskan Husky Encephalopathy

Alaskan Husky Encephalopathy (AHE) has been previously proposed as a mitochondrial encephalopathy based on neuropathological similarities with human Leigh Syndrome (LS). We studied 11 Alaskan Husky dogs with AHE, but found no abnormalities in respiratory chain enzyme activities in muscle and liver, or mutations in mitochondrial or nuclear genes that cause LS in people. A genome wide association study was performed using eight of the affected dogs and 20 related but unaffected control AHs using the Illumina canine HD array. SLC19A3 was identified as a positional candidate gene. This gene controls the uptake of thiamine in the CNS via expression of the thiamine transporter protein THTR2. Dogs have two copies of this gene located within the candidate interval (SLC19A3.2 – 43.36–43.38 Mb and SLC19A3.1 – 43.411–43.419 Mb) on chromosome 25. Expression analysis in a normal dog revealed that one of the paralogs, SLC19A3.1, was expressed in the brain and spinal cord while the other was not. Subsequent exon sequencing of SLC19A3.1 revealed a 4bp insertion and SNP in the second exon that is predicted to result in a functional protein truncation of 279 amino acids (c.624 insTTGC, c.625 C>A). All dogs with AHE were homozygous for this mutation, 15/41 healthy AH control dogs were heterozygous carriers while 26/41 normal healthy AH dogs were wild type. Furthermore, this mutation was not detected in another 187 dogs of different breeds. These results suggest that this mutation in SLC19A3.1, encoding a thiamine transporter protein, plays a critical role in the pathogenesis of AHE.University of California, Davis. School of Veterinary Medicine. Center for Companion Animal Healt

Intraperitoneal antineoplastic drug delivery: experience with a cyclophosphamide, vincristine and prednisolone protocol in cats with malignant lymphoma.

In this retrospective study, the efficacy and safety were examined for an intraperitoneal chemotherapy protocol-cyclophosphamide, vincristine and prednisolone (IP-COP) in 26 cats with malignant lymphoma. Certainly in cats fiercely resisting IV administration the IP route is a more practical method, safer for the administrator and less stressful for the cat. Complete remission (CR) rate was 76.9% (n = 20). Median duration of first remission was 421 days. Estimated 1- and 2-year disease free period were 67.1 and 48.0%, respectively. Median duration of survival was 388 days and estimated overall 1- and 2-year survival periods were 54.7 and 46.9% respectively. Young cats had a more favourable prognosis. Reaching CR was essential for long-term survival. No specific IP-related adverse events (AE) were seen. AE were generally scored as mild and were not excessively abundant. These results indicate that the IP route is a safe and effective alternative for the administration of COP protocol chemotherapeutics

Cytogenic analysis of cell lines derived from metastases of a mammary carcinoma in a dog

Three cell lines derived from two metastases of a mammary carcinoma in a femal dog were analyzed cytogenetically. All three cell lines showed a modal chromosome number of 76, with ranges of 74-77, 72-78, and 73-78. A biarmed chromosome in addition to the X chromosomes was observed in all cells of one cell line, and in a part of the cells of the other two cell lines. Results of banding analyses indicated that this chromosome was identical in the three cell lines, and can thus be considered a clonal marker. Additional biarmed chromosomes have not been reported previously from mammary tumor cells, although their presence is rather common in other canine neoplasms

Expression of transferrin receptor-1 (TFR-1) in canine osteosarcomas

Due to high rates of proliferation and DNA synthesis, neoplastic cells have higher requirements of iron than normal cells. For that reason, neoplastic cells have remodelled iron metabolism pathways, over-expressing genes encoding for iron uptake proteins, among which Transferrin Receptor-1 (TFR-1). Accumulating evidence has proven that overexpression of TFR-1 and high Iron concentration, are both widespread condition of cancer cells, both essential to tumour onset and progression. We studied TFR-1 and PCNA immunohistochemical expression in fifteen (15) Canine osteoblastic osteosarcomas (COS). After immunohistochemical staining, counting of TFR-1 positive cells by two independent observers showed that 85%-95% of neoplastic cells were strongly labelled at cytoplasmic level by anti-TFR-1 antibody in all examined COS. Furthermore, 70%-80% of neoplastic cells were positively labelled at the nuclear level by PCNA. Surprisingly, about 100% of intratumour vascular endothelial cells were also positive, whereas extratumour vascular endothelial cells were negative. The latter is an interesting finding, as TFR-1 is usually not expressed in normal vasculature, with the exception of normal brain vascular endothelium, where it allows transport of transferrin, and thus iron, into tissues, suggesting a similar function here to support cancer growth. The early results presented highlight the relevance of TFR-1 expression in canine OS, suggesting therapies involving both TFR-1 and Iron metabolisms in dogs with osteosarcoma should be developed