Yasuyuki Horisaka

Muscle tissue reactions to implantation of bone matrix gelatin

Histologic changes of muscle tissue in the early stage of heterotopic osteogenesis induced by syngeneic insoluble bone matrix gelatin (BMG) with bone morphogenetic protein in rats was observed by light and electron microscopy. BMG induced cartilage in muscle tissue by Day 7 after its implantation, woven bone by Day 10, and lamellar bone with bone marrow by Day 14. The new findings in this work include (1) the disappearance of the basement membrane of muscle fibers; (2) the activation of the satellite cells of muscle fibers; (3) the appearance of fibroblastlike cells that closely resembled activated satellite cells among the degenerated muscle fibers or on the surface of the BMG; and (4) the change of fibroblastlike cells to chondroblasts or osteoblasts. These findings suggest that intramuscular implantation of BMG caused the conspicuous disappearance of the basement membrane of the muscle fiber and may play a part in osteogenesis induced by BMG.

Effect of Bupivacaine on Muscle Tissues and New Bone Formation Induced by Demineralized Bone Matrix Gelatin

Heterotopic bone formation induced by demineralized bone matrix gelatin (BMG) in bupivacaine-HCl-treated skeletal muscle was examined histologically. BMG was obtained by dehydrating diaphyseal shafts of femora and tibiae of male, 4-week-old Sprague-Dawley (SD) rats, cutting it into chips, and demineralizing and extracting the chips with various solutions. The BMG was implanted into the rectus abdominis muscle of male, 5-week-old SD rats, bupivacaine-HCl was injected at the same site, and the resulting plaques of tissues were examined histologically on days 5, 10, 15 and 20 after BMG implantation. Heterotopic bone formation occurred in all animals. The bupivacaine-treated group had more degenerated and injured muscle fibers, and more osteocytes than the control group. Electron microscopy showed that the basement membrane of muscle fibers was discontinuous and that many mononucleated cells resembling activated satellite cells were present on day 5. Many fibroblasts, undifferentiated mesenchymal cells and myogenic cells were seen in the area around the BMG. In new bones there were few osteocytes on day 10, but their numbers were increased on days 15 and 20 after implantation, especially in the bupivacaine-treated group. The population of osteocytes that increased rapidly may have included mononucleated cells similar to activated satellite cells.

Influence of Palatal Form of Molar Region on Tongue Movement for Pronunciation of /s/ Sound.

The purpose of this study was to investigate the influence of palatal form changing with the position of upper posterior artificial teeth on tongue movement for pronunciation of /s/sound. Subjects were seven males and speech material was /asa/. Two experimental palatal plates were made for each subject: a normal 1.5-mm-thick plate and the plate augmented by a 4-mm-thick lateral seal of palatal surface. Tongue-palatal contacts were measured by a dynamic palatography when wearing either of the two plates. The influence of the palatal form was estimated using the following parameters: the onset of the tongue-palate contact, maximum contact speed, the timing of the constriction for /s/, and palatogram pattern at the constriction and consonant duration for /s/.The speech behavior when wearing the augmented plate was divided into 4 groups comparing to normal plate:Group 1: Tongue-palate contact started earlier, maximum contact speed decreased and the timing of the constriction was constant.Group 2: The onset of tongue-palate contact and maximum contact speed were constant. Butthe timing of the constriction was delayed.Group 3: Tongue-palate contact started earlier, maximum contact speed decreased and thetiming of the constriction was delayed.Group 4: Temporal aspect of tongue-palate contact was constant. But the consonant durationwas shorter and abnormal palatogram pattern was observed.