ABSTRACT. A seven-year-old male elk (Cervus elaphus nelsoni) was euthanized and necropsied after having a 3-week history of body weight loss, emaciation, excessive salivation, teeth grinding, fever, anorexia, and respiratory distress. The elk was imported into Korea from Canada on March 9, 1997. Gross pathologic findings were restricted to a diffuse fibrinous pneumonia. Microscopic lesions included mild neuronal vacuolation and spongiform change in the neuropil of selected brain stem nuclei and generalized astrocytosis. Immunohistochemistry for protease-resistant prion protein (PrP res ) was positive in all brain sections but more pronounced in the section of the obex of the medulla. And the PrP res was also detected by western immunoblotting in the brain and spinal cord. All the remaining elk and deer that had been in contact with this elk were destroyed and negative for chronic wasting disease (CWD). To our knowl edge, this is the first case of CWD occurring outside of the U.S.A. and Canada.

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Transmissible venereal tumor (TVT) is a well-documented transplantable tumor in dogs, with no breed or sex predilection and a low metastatic rate. In this report, a 2-year-old intact female Mastiff that had numerous, rapidly growing masses throughout the subcutis mainly at the dorsal body plane, the caudal half of the ventral abdomen, and around the vulva was euthanized due to poor prognosis. Neoplastic nodules similar to those seen in the subcutis were also noted in the lung, anterior mediastinum, liver, spleen, kidney, and superficial and deep lymph nodes in both abdominal and thoracic cavities. The neoplastic nodules from the subcutis as well as metastatic foci revealed similar cytologic and histologic features, which were consistent with canine TVT. By immunohistochemical staining, the neoplastic cells were positive for lysozyme and vimentin but were negative for cytokeratin, desmin, CD3, and CD79a. The diagnosis of the TVT was further supported by the identification and analysis of long interspersed nuclear elements (LINE) from paraffin-embedded tumor tissue. This case is a rare example of TVT with multiorgan metastasis. In this case, the polymerase chain reaction technique was useful in differential diagnosis of canine round cell tumors because this technique can be applied in retrospective as well as future study.

Summary Pig embryonic stem cells (pESCs) have been considered an important candidate for preclinical research on human therapies. However, the lack of understanding of pig pluripotent networks has hampered establishment of authentic pESCs. Here, we report that FGF2, ACTVIN, and WNT signaling are essential to sustain pig pluripotency in vitro . Newly derived pESCs were stably maintained over an extended period, and capable of forming teratomas that contained three germ layers. Transcriptome analysis showed that pESCs were developmentally similar to late epiblasts of preimplantation embryos and in terms of biological functions resembled human rather than mouse pluripotent stem cells. However, the pESCs had distinct features such as coexpression of SSEA1 and SSEA4, two active X chromosomes, and a unique transcriptional pattern. Our findings will facilitate both the development of large animal models for human stem cell therapy and the generation of pluripotent stem cells from other domestic animals for agricultural use.

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