Neuropeptide Y- and vasoactive intestinal polypeptide-like immunoreactivity in adjuvant arthritis: effects of capsaicin treatment.

The occurrence of the neuropeptides vasoactive intestinal polypeptide (VIP) and neuropeptide Y (NPY) in ankle joints and dorsal root ganglia (L2-L6) was analyzed in normal and arthritic Lewis rats. In addition the effect of capsaicin pretreatment was investigated. The study included 92 rats consisting of 4 groups, 23 rats in each; normal rats, normal rats given capsaicin, arthritic rats and arthritic rats pretreated with capsaicin. The localization of the neuropeptides was assessed by immunohistochemistry and the tissue concentrations were determined by radioimmunoassay (RIA). In the arthritic rats, there was a slight increase in NPY immunoreactive nerve fibres in the ankle joint synovium and bone marrow, as compared to normal rats. Notably, there was an intense fluorescence and significant increase (p < 0.01, 41%) in the number of NPY-positive megakaryocytes in the tibial bone marrow of arthritic rats. RIA showed that the concentration of NPY-like immunoreactivity (LI) was increased by 50% in the ankle joint. Pretreatment with capsaicin did not affect the increased level of NPY-LI in the ankle joint of arthritic rats. The concentration of NPY-LI in the dorsal root ganglia was not altered in arthritic rats, nor was it affected by the capsaicin treatment. No NPY immunoreactive cells could be detected in the dorsal root ganglia. The number of VIP immunoreactive nerve fibres observed in ankle joints of arthritic and normal rats did not differ. However, RIA measurements showed an 11% increase in the VIP concentration in arthritic rats, which was unaffected by capsaicin treatment. In dorsal root ganglia, RIA disclosed a 21% increase in VIP-LI, although no VIP-positive cells could be detected. Capsaicin treatment did not affect the increased concentration of VIP-LI in the dorsal root ganglia.

Incorporation of autoclaved autogeneic bone supplemented with allogeneic demineralized bone matrix. An experimental study in the rabbit.

Resected, autoclaved, and reimplanted bone supplemented with allogeneic demineralized bone matrix (DABM) was compared with nonsupplemented bone in the reconstruction of bilateral ulnar defects in seven adult rabbits. The reconstructions were studied in vivo with the use of serial radiography, scintigraphy (99mTc-MDP), and bone mineral determination. After sacrifice at 16 weeks, the ulnar specimens were analyzed with the use of high-resolution radiography, autoradiography (45Ca), and histologic study. Scintigraphically, the uptake was significantly higher in the DABM-supplemented implants during the entire investigation. Bone mineral content was significantly higher at four and eight weeks in the DABM-supplemented implants, compared with the nonsupplemented implants, but later it equalized. New bone formation, as reflected by 45Ca incorporation, still occurred at 16 weeks in both types of implants, but it was more intense in the DABM-supplemented ones. Radiography and histologic analysis showed more new bone in the DABM-supplemented reconstructions than in the nonsupplemented ones. High-resolution radiography showed complete incorporation of all seven DABM-supplemented implants, whereas there was nonunion in five of seven nonsupplemented reconstructions. The current study indicates that resected, autoclaved, and reimplanted diaphyseal segments supplemented with demineralized allogeneic bone matrix incorporate better than nonsupplemented implants of autoclaved autologous bone.

Incorporation of nonviable bone grafts. Autoclaved autogeneic and frozen allogeneic bone grafts compared in the rabbit.

In 14 adult rabbits the middle third of the ulna was resected bilaterally followed by reimplantation of resected bone after autoclaving on one side and transplantation of allogeneic bone on the other. In 7 animals the bilateral implants were supplemented with allogeneic bone matrix. The reconstructions were studied in vivo by serial radiography, scintigraphy, and bone mineral determination. The animals were killed at 16 weeks, and the ulnar reconstructions further studied by high resolution radiography, 45Ca autoradiography, and histology. In both types of nonsupplemented reconstructions, new bone formation was poor; nonunion occurred in three out of seven autoclaved reimplants and in five out of seven allogeneic transplants. Supplemented with allogeneic bone matrix, both types of reconstructions exhibited abundant new bone formation and complete incorporation of all implants. Enhancement of new bone formation is probably more important than the type of nonviable bone graft chosen for reconstruction of large skeletal defects.

Diaphyseal reconstruction by autoclaved bone. Reimplantation experiments in rabbits.

In 8 adult rabbits, reconstruction of large humeral defects by reimplantation of resected, autoclaved bone supplemented with allogeneic bone matrix was investigated with respect to incorporation (radiography, histology), bone metabolic activity (scintigraphy, autoradiography), and strength (torsional test). Radiography showed that seven out of eight implants were incorporated at 3 months. Scintigraphy and autoradiography disclosed bone metabolic activity in the reconstructions still 8 months postoperatively. Histological investigations evidenced abundant new viable bone that partially had replaced the implants at 8 months. The torsional test disclosed that the strength of the reconstructions was 84 per cent of normal 8 months after reimplantation. Our experiment supports the concept of reimplantation of autoclaved tumorous bone supplemented with allogeneic bone matrix in reconstruction after local resection.