Objective. Pluripotent mesenchymal stem cells (MSC) have been isolated and well characterized from several tissue sources, including bone marrow stroma. MSC from different animals showed slight differences in morphology and in the potential to differentiate. In the present study, we isolated MSC from bovine bone marrow and induced chondrogenesis in order to establish a new experimental model of stem cell research. Methods. Bone marrow was harvested from 8 calves. For inducing chondrogenesis, MSC were cultured in pellet culture system in a chemically defined medium supplemented with 0 and 10 ng/mL of transforming growth factor b1 (TGF-b1).

Plasma histamine concentrations (PHCs) were measured serially over 9 months or until death in 11 dogs with mast cell tumors (MCTs). Eight dogs had grossly visible disease and the other 3 dogs had microscopic disease. Initial PHCs in the dogs with gross disease were significantly higher than PHCs in healthy dogs (median, 0.73 ng/mL and 0.19 ng/mL respectively; P Ͻ .009), whereas initial PHCs in dogs with microscopic disease showed no difference from controls. Seven dogs subsequently had progressive increases in PHC, and developed hyperhistaminemia (median, 14.0 ng/mL; range, 5.11-30.1 ng/mL). These 7 dogs died from MCTs, and 1 had general weakness with rapid lysis of a large tumor burden after radiation therapy. PHCs of the other 4 dogs were less than 1 ng/mL during the study. These 4 dogs were still alive with adequate control of the tumor at the conclusion of the study. Four of the 11 dogs initially had gastrointestinal (GI) signs, which abated soon after administration of histamine-2 (H-2) blockers. No significant difference was found between PHCs in dogs with GI signs and those without GI signs (median, 0.86 ng/mL and 0.35 ng/mL, respectively). Thereafter, 7 dogs had serious GI complications for which H-2 blocker therapy was ineffective. PHCs in these 7 dogs were extremely high (median, 12.2 ng/mL; range, 3.42-30.1 ng/mL). Results of this study demonstrated that PHC was one factor related to disease progression, and indicated that marked hyperhistaminemia was associated with the GI signs refractory to H-2 blocker therapy in dogs with MCTs.

ABSTRACT. Odontogenic cysts, which showed cystic radiolucency in the jaw bone by radiographic examination and computed tomography, were enucleated by operation in 3 dogs. One dog had a odontogenic keratocyst in the incisive bone of the right maxilla and another 2 cases revealed dentigerous cysts in the mandible. These cyst walls were enucleated or transpired by semiconductor laser. Afterwards, osteogenesis was confirmed at the defective part of jaw bone by extirpation of the cyst in all cases, and no recurrence has been noted in any cases. Odontogenic cyst is a disease which should be treated by surgical extirpation or transpiration. KEY WORDS: canine, dentigerous cyst, odontogenic keratocyst.

ABSTRACT. A new cell line (CoMS) was established from a 3-year-old male mongrel dog with mast cell tumor of the oral mucosa. CoMS cells grow in suspension with a doubling time of 27.0 ± 0.7 hr. The cytoplasmic granules were formalin-sensitive, showed diverse appearances in their ultrastructural findings and contained heparin proteoglycan and neutral protease chymase. Calcium ionophore A23187, substance P and concanavalin A caused significant histamine release from CoMS cells, while compound 48/80 failed to release histamine. This cell line will make an available source for studies on canine mast cell tumors. KEY WORDS: canine, cell line, mast cell tumor.J. Vet. Med. Sci. 63(9): 1031-1034, 2001 Mast cell tumor (MCT) is one of the common neoplasms in dogs, accounting for 7% to 21% of all skin tumors and 11% to 27% of all malignant skin tumors [19]. There are still some dilemmas caused by its unpredictable biological behaviors with regard to diagnosis and treatment of MCT [9]. Studies on several neoplastic cell lines of human or rodent mast cells such as HMC-1, P-815 and RBL-2H3 have provided many informations about mast cell biology [17,18,20]. There will be anatomical, biochemical, immunological and pharmacological differences between human, rodent and canine mast cells. Available cell lines of canine MCT are therefore required for the research on this disease.In this paper, we describe a successful establishment of a new canine MCT cell line named CoMS in continuous culture and report morphology, histamine release activity and granular components such as proteases and heparin of CoMS cells.CoMS cell line was obtained from a mucosal mass in the lower lip of a 3-year-old male mongrel dog with MCT. The dog was referred to the Veterinary Teaching Hospital of Hokkaido University with massive swelling of a left lower lip and both cervical lymph nodes. The clinical managements were consisted of surgical excision, radiotherapy and chemotherapy. In spite of these treatments, the dog died of deterioration of general conditions 56 days after the first admission. Multiple gastroduodenal ulcers and multiple distant metastases to the internal organs such as the liver, spleen, kidneys and lungs but no metastasis to the skin were observed at necropsy.The specimen of CoMS collected at surgery was initially maintained in vivo passage in 5-week-old female C.B-17 severe combined immunodeficiency (SCID) mice (Clea Lab., Tokyo, Japan) by subcutaneous implantation, then the tumor tissues excised from the mice were used for establishment of the cell line in vitro.These tumor tissues were minced finely in RPMI 1640 medium containing 2 mg/ml sodium bicarbonate, 25 mM Hepes buffer, 100 U/ml penicillin and 100 µg/ml streptomycin, filtrated through a stainless mesh and washed two times in phosphate buffered saline. The isolated cells were then suspended and incubated in the above RPMI 1640 medium with 10% heat inactivated fetal calf serum (FCS) at 37°C in a humidified atmosphere of 5% CO 2 and were passaged every 4 to 6 day. The cell line n...