The purpose of this study was to investigate the influence of 4-META/MMA-TBB adhesive resin (4-META resin) on osteodentinogenesis of transplanted pulp in vivo. Dental pulp was obtained from the incisors of adult rabbits. 4-META resin was applied to the pulp tissue, and the pulp tissue with 4-META resin was autotransplanted beneath the renal capsule with the pulp side touching the kidney. Pulp tissue alone was also transplanted as a control. The animals were sacrificed at 3, 7, and 14 days after the experiment, and the specimens were examined morphologically. At 3 days, proliferation of mesenchymal cells was observed, and alkaline phosphatase activity (ALP) and osteocalcin were detected throughout the entire transplanted pulp area. In the experimental case, a thin, highly electron dense zone and a granular layer were observed. Under this layer, only a cell-membrane-like structure, a cell with an unclear nucleus, a nucleus alone, and an organelle-like structure could be seen. Furthermore, an exudative layer with many neutrophils was observed, and apoptotic-body-like structures were also found in some areas. On days 7 and 14 in the control group, osteoblast-like cells had proliferated, and osteodentin formation was initiated throughout the entire transplanted pulp area. In the experimental cases at 7 and 14 days, the entire transplanted area had become osteodentin except for a thin fibrous layer under the 4-META resin. These results suggested that the components of 4-META resin such as MMA and 4-MET (A), which guide the polymerization, might cause degeneration of, but not disturb, the wound healing of the pulp tissue.

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Interleukin-1 (IL-1), which is produced by Kupffer cells and sinusoidal endothelial cells, may play an important role in immunological and microvascular responses to a variety of stimuli in the liver. The responses of the hepatic microvasculature including phagocytic activity of sinusoidal lining cells to IL-1α were examined in C₅₇Bl/6 mice in vivo and using electron microscopy. One hour after recombinant mouse IL-1α was injected at doses of 80 U, the low dose group, and 800 U, the high dose group, the phagocytic activity of sinusoidal lining cells showed significant differences between the two treated groups and between the two groups and the controls. In the low dose group, the numbers of sinusoids containing blood flow and of leukocytes adhering to the sinusoidal lining remained unchanged, but the former decreased and the latter increased significantly in the high dose group. Ultrastructurally, Kupffer cells that phagocytosed latex particles appeared to have decreased in number while the sinusoidal endothelial cells became phagocytic. A considerable number of leukocytes were seen adhering to the sinusoidal endothelium. These findings demonstrate that IL-1α not only elicited sticking and plugging by leukocytes in sinusoids but also activated phagocytic functions in the hepatic sinusoidal endothelial cells. These endothelial responses are similar to those seen following FV₃ virus infection, chronic administration of ethanol, or a combination of cocaine and ethanol, or during extracorporal perfusion, suggesting that IL-1 may participate in these responses.

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When arthroscopy of the temporomandibular joint (TMJ) is performed, we often observe differences in the resistance of hydraulic pressure during intra-articular pumping. It can be speculated that intra-articular adhesion and contracture of the capsule and ligament may cause these differences in resistance. In order to measure the changes in intra-articular hydraulic pressure before and after arthroscopic ablation surgery, seven cases were examined by balloon pumping technique. We concluded that the values of intra-articular hydraulic pressure are implicated in the severity of the internal derangement of TMJ.

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