Acrylic bone cement is self-curing cement comprising of liquid and powder component of methyl methacrylate (MMA). It has been used extensively in orthopedics; however, adverse effects were associated with its use. Hence we investigated in this paper the possibility of new cement utilizing methacrylates with lower toxicity than MMA. LD50s of candidate monomers were determined with administration to the medullary cavity of the rat’s femur. 2-Ethylhexyl methacrylate (EHMA) and trimethylolpropane trimethacrylate (TMP) demonstrated greater LD50 values of 187 mg/kg and 380 mg/kg, respectively, than MMA (108 mg/kg); they were selected as the liquid components of the new cement. The copolymer of EHMA and cyclohexyl methacrylate was then selected as the powder component. With this combination, we developed the new cement (EHMA cement). Temperature rise during polymerization of EHMA cement was 9°C–13°C, which was signifi cantly lower than that of conventional cement. The compression strength of the polymerized EHMA cement was 57 MPa without TMP, and 67 MPa with TMP (15 wt%). Thus we concluded that new EHMA cement was slightly inferior in the compression strength than the conventional cement. However, it was characterized by the low toxicity of utilized monomers and the low temperature rise during polymerization.

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The aim of this study was to investigate changing mechanical properties of the bolus during mastication and to quantify mechanical properties of the fi nal bolus at swallowing. Changing mechanical properties of the bolus of three different types of foods (rice cracker, cheese and peanuts) by twelve normal dentitions were investigated by principal component analysis (PCA) on six mechanical properties (rupture energy, elasticity, viscosity, hardness, cohesiveness and adhesiveness). The raw data of cohesiveness immediately before swallowing was always constant. In all three food samples, the results by PCA on six parameters indicated that cohesiveness was independent from the remaining fi ve parameters, and two factors were extracted on these fi ve parameters by PCA. Furthermore, factor structure of bolus at swallowing showed no difference between the three food samples in spite of the variations in the raw data. The mechanical properties of swallowable bolus were clarifi ed for the fi rst time.

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Aim: T cell-mediated immunity is involved in the pathogenesis of atherosclerosis and arteriosclerosis. This study examined whether the 4-1BB pathway affects the development of arteriosclerosis after vascular injury. Methods and Results: The left or right femoral arteries of adult male mice weighing 22 to 25 g were injured with a straight spring wire. The injured artery was excised 28 days later. Confocal microscopy revealed intense expression of both 4-1BB and 4-1BBL in the developing neointima and media. Similar results were obtained on immunoblotting analysis of lysates of the injured arteries. We gave mice an injection of 100 μg or 200 μg 4-1BB-fused with human immunoglobulin (Ig) every other day over the course of 5 days. As compared with untreated controls (intima/media ratio, 2.13 ± 0.37, n=10), the intima/media ratio was smaller in mice treated with 200 μg of 4-1BBIg (1.20 ± 0.30, n=6, p<0.05), but not in mice treated with 100 μg of 4-1BBIg (1.56 ± 0.27, n=9). Conclusions: 4-1BB inhibits neointimal hyperplasia after vascular injury. Our fi ndings suggest that 4-1BB is involved in injury-induced neointimal hyperplasia and may be an effective target for the treatment of neointimal hyperplasia.

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