The usefulness of collagen fibers and the YIGSR sequence (Tyr-lle-Gly-Ser-Arg) of laminin for nerve regeneration were examined in vivo. Type I collagen gel (G-group), Type I collagen fibers (F-group), Type I collagen fibers coated with laminin (L-group) or the YIGSR sequence (Y-group) were packed into silicone tubes, 15 mm long, and transplanted to the sciatic nerves of Wistar rats. Empty silicone tubes were used as the control. The animals were sacrificed 8 weeks after transplantation. Bridging of the nerve was confirmed in the F-(7/12), Y-(7/10) and L-group (6/10), but no bridging was observed in any of the animals of the G- and control group. Nerve regeneration among the space of collagen fibers was observed, and it was suggested that fibroblasts infiltrated the gap in the substance of the degenerated collagen fibers were followed by Schwann cells on the basis of immunocytochemistry. The number of myelinated axons per regenerated tissue in the tube (density), and total area of myelinated axons per measured regenerated tissue in the tube (% axon area) in each the L- and Y-group were significantly higher than that in the F-group (P < 0.05). These results suggest the possibility of obtaining adequate nerve regeneration with new artificial materials only.

Changes in bone mineral density with age were measured in the distal radius of healthy adults using dual energy X-ray absorptiometry. A total of 2789 healthy women (20-95 years old) and 1255 healthy men (20-87 years old), and 72 women (52-94 years old) and 23 men (51-79 years old) with fractures of the distal radius were assessed. Bone mineral density remains relatively stable in men despite aging, and was significantly higher than in women in every decade. In women aged 70 years and more, the bone mineral density was significantly lower in the fracture group than the non-fracture group. In men with fractures of the distal radius, there were no significant differences between bone mineral density and age. In the fracture groups loss of radial inclination after reduction correlated with decreased bone mineral density, but there was no significant regression between bone mineral density and the decrease in radial length or palmar tilt.

We evaluated neurotization after transplantation with lyophilized nerves, muscles, and arteries, and examined the possibility of practical application of long bridging grafts. Grafts of 10 mm and 25 mm of lyophilized nerves, muscles, and arteries harvested from Fisher rats were transplanted to the sciatic nerves of recipient Lewis rats. The histological changes undergone by short grafts were observed at weekly intervals. The sham-operated and isograft groups were used to compare the results of long grafts. In both the nerve and muscle-graft group, regenerated axons grew out through the residual basement membrane tube. But in the muscle graft group, phagocytosis of myofibril debris took longer than that of degenerated axons. No statistical differences were found between results of TSI, induced EMG, and quantitative analysis of myelinated axons in the nerve and muscle graft groups. No neurotization was noted in the long artery graft. In long grafts, laminin found on the basement membrane may not be sufficient to accelerate neurotization, and arteries should not be used for tubulization.