This study examined the inhibitory effect of a new bisphosphonate (TRK-530) on wear debris-mediated bone resorption in a rat osteolysis model involving continuous infusion of high density polyethylene (HDPE) particles. TRK-530 (TRK) is a novel synthetic bispliosphonate that has been shown to decrease the level of tumor necrosis factor alpha (TNF-a) in the bone marrow of rats with adjuvant arthritis. Forty Wistar rats were randomized to two groups ( i i = 20 each). In each rat, 8 Kirsliner (K) wire was inserted into tlie femur and HDPE particles were continuously infused into the knee joint. Thereafter, the animals were subcutaneously injected with saline (control group) or I mg/kg of TRK (TRK group) every second day, and were sacrificed at 4 or 8 weeks after surgery. Radiographs obtained a t the time of sacrifice were evaluated for periprosthetic osteolysis. We also examined the thickness of the reactive membrane a s well as the number of osteoclast-like cells around tlie K-wire. In addition, we examined the expression of genes for bone-resorbing cytokines in the reactive membrane. Radiographic peri-implant osteolysis was more frequent in the control group coinpared with the TRK group at each time of assessinent 0, < 0.01). The interfacial membrane was significantly thinner in the TRK group coinpared with the control group ( p < 0.01) and the average number of osteoclast-like cells around tlie Kwire was significantly fewer in the TRK group (p < 0.01). I n addition, the expression of interleukin 1 -alpha messenger ribonucleic acid (IL-la niRNA) and TNF-a niRNA was suppressed in the T R K group at each time of assessnient. We conclude that the T R K can inhibit the formation of inflaniinatory peri-implant osteolysis induced by HDPE particles.

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ABSTRACT. Leptin is the ob gene product secreted from adipocytes in mammals, and thereby its plasma level reflects body fat content. To establish an assay method for leptin in the dog, rabbit anti-canine leptin antibody was obtained using canine recombinant leptin as an antigen. This antibody reacted to canine leptin much stronger than mouse, rat and human leptins. Sandwich enzyme-linked immunosorbent assay (ELISA) using this antibody was developed. The serum leptin levels of 13 healthy dogs were in a range from 1.4 to 5.6 ng/ml with the mean ± SEM of 3.0 ± 0.3 ng/ml.-KEY WORDS: canine, ELISA, leptin.

Study Design. Retrospective case-control study. Objective. To investigate the prevalence and characteristics of diffuse idiopathic skeletal hyperostosis (DISH) in vertebral fracture patients admitted to our hospital. Summary of Background Data. Although vertebral fracture is generally treated conservatively with rest and use of a corset, surgery with rigid internal fixation is recommended for vertebral fractures in patients with DISH. Thus, treatment strategies for vertebral fracture differ according to the presence or absence of DISH. However, only a few studies have investigated the prevalence of DISH in vertebral fracture patients. Methods. A total of 159 patients (49 men and 110 women, with a mean age of 82.9 years) who were diagnosed with fresh vertebral fracture and required admission to HITO Hospital. The diagnosis of fresh vertebral fracture was made using x-ray imaging, computed tomography, and magnetic resonance imaging, and the presence or absence of DISH was assessed. In addition, age, sex, bone mineral density ( % young adult mean), blood test results, treatment, and length of hospital stay were compared between patients with and without DISH. Results. The proportion of patients with DISH among the patients with vertebral fracture was 33.9% (54 of 159 patients). The proportions in men and women were 38.8% and 31.8%, respectively, with no significant difference between sexes (P = 0.39). The patients in the DISH group were older than those in the non-DISH group (83.6 vs. 79.4 years, P = 0.009), and the DISH group had higher glycated hemoglobin A1c (P = 0.005), higher bone mineral density (P = 0.042), and longer length of hospital stay (P = 0.0001) compared with those in the non-DISH group. Conclusion. The proportion of patients with DISH among the vertebral fracture patients was 33.9%. Given that patients with DISH may require different treatment approaches, careful observation is needed. Level of Evidence: 3

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