Akira Matsuhashi

Influence of chain length of N-acetyl-D-glucosamine and D-glucosamine residues on direct and complement-mediated chemotactic activities for canine polymorphonuclear cells

The direct and complement-mediated chemotactic activities (CA) of N-acetyl-d-glucosamine (GlcNAc), d-glucosamine (GlcN), GlcNAc and GlcN oligomers, chitin and chitosan for canine polymorphonuclear cells (PMNs) were investigated in vitro. GlcNAc6 and GlcN56 provided the most effective stimulation of CA, with GlcN6 having a seven-fold stronger effect than GlcNAc6. Serum incubated with chitin and chitosan (37 °C, 30min) had a similar CA to that of zymosan. The total complement activity (CH50) of serum mixed with chitin and chitosan was lower than control level, but monomers and oligomers of GlcNAc or GlcN did not decrease complement activity. Subcutaneous injection of GlcN6 and chitosan enhanced more PMN migration than GlcNAc6 and chitin in vivo. It was demonstrated that GlcN residues induced higher direct CA than GlcNAc residues, while complement-mediated CA was only induced by chitin and chitosan, but not by GlcNAc, GlcN and their oligomers.

Chitosan-inducing hemorrhagic pneumonia in dogs

Abstract Various amounts of chitosan (10–200 mg/kg) were administered subcutaneously to dogs. Anorexia and mortality were observed in dogs given doses above 50 mg/ kg, and above 150 mg/kg, respectively. In hematologic findings leukocytosis and increasing of serum LDH2 and LDH3 isoenzymes were characteristic. From the findings of autopsy, severe hemorrhagic pneumonia was observed in all dead dogs. Chitosan causes lethal pneumonia to dogs.

Subcutaneous injected chitosan induces systemic activation in dogs

Abstract Systemic activation by subcutaneous administration of chitin, chitosan, and chitosan oligomer was investigated in dogs by determining the chemiluminescence (CL) response of circulating polymorphonuclear cells (PMN). Chitin (10 and 100mg/kg), chitosan oligomer (10mg/kg), latex beads (10mg/kg) and physiological saline (10ml) did not cause activation of PMN. However, chitosan caused systemic activation of PMN in a dose-dependent manner. The peak CL response of PMN was significantly increased in the 1 and 10mg/kg chitosan groups at 3 days after administration. In addition, chitosan (10mg/kg) prevented a decrease of the CL response in dogs given dexamethasone. Serum obtained from the 10mg/kg chitosan group significantly activated PMN from normal dogs. At 3 days after chitosan administration, the serum level of complement component 3 (C3) was increased about 1.6 times that of the prechitosan C3 level. In conclusion, subcutaneous administration of chitosan induces systemic activation of both PMN and serum.

Chitin induces type IV collagen and elastic fiber in implanted non-woven fabric of polyester

The non-woven fabric of polyester (control) and the composite material of the non-woven fabric of polyester and chitin (Chitipack P) were implanted to bovine flexor tendon. After 3 weeks implantation, type IV collagen and elastic fibers were significantly increased and type I collagen was decreased in Chitipack P in comparison with control. The breaking strength was about twice as high in Chitipack P than in control. The polykaryocytes in the control were more difficult to digest for the collagens. Angiogenesis in the implanted non-woven fabric and in the neighboring resected tendons was much stronger in Chitipack P. Chitin induced type IV collagen and elastic fibers in the prostheses.

Effect of chitin on nonwoven fabric implant in tendon healing

Abstract In 12 sheep (24 forelimbs), a 12 mm section of flexor digitorum superficialis tendon was removed. The tendons were repaired with (1) suture only (control group, n = 8), (2) suture plus implanted nonwoven polyester fiber (NWF group, n = 8), and (3) suture plus implanted nonwoven fiber and chitin complex (CP group, n = 8). All tendons were immobilized for 6 weeks. Macroscopic and histomorphometric evaluations were performed on two limbs from each treatment group in weeks 1, 3, 6, and 12. Macroscopic findings showed no significant differences among the three groups in any parameters. At the implant area, histomorphometry indicated that immature and intermediate fibroplasia was significantly greater in the CP group compared to the NWF group in week 1 and in weeks 3 and 6, respectively. In the area surrounding the implant, there were no significant differences among the three groups.

Systemic effect of chitin after intravenous administration to dogs

Abstract The systemic effect of chitin and chitin oligomer after intravenous administration was investigated in dogs by determining the chemiluminescence (CL) response and the white blood cell count (WBC). Chitin oligomer (2mg/kg) and physiological saline (5ml) did not have a systemic effect. However, in the dogs injected with chitin, WBC decreased significantly from 1 to 4 h after injection and then increased gradually to 1.4 times the pre-injection level at 72 h, while CL was significantly increased 1–2 h after injection.