Objective To prepare carboxymethylchitin and study its properties. Methods Chitin was prepared from fresh shrimp shells and then carboxymethylchitin was prepared by the methods of alkalization and etherification as well as by the purification technique. The deacetylation degree of carboxymethylchitin was determined by the doublejump potentiometric titration method; the substitution degree was determined by the element analysis method; the carboxymethyl substitution position was analyzed by the Fourier transform infrared spectroscopy apparatus and the nuclear magnetic resonance spectroscopy apparatus; the relative molecular weight and its polydispersity were determined by the gel permeation chromatography with the multiple angle laser light scattering detection; the biological properties were tested according to the GB/T 16886 biological evaluation on medical devices. Results Carboxymethylchitin could be prepared by alkalization and etherification from chitin which was prepared from fresh shrimp shells by decalcification and deproteinization. The deacetylation degree of carboxymethylchitin was 13.76% according to the doublejump potentiometric titration; the degrees of deacetylation and substitution were 14.53% and 1.239 0 respectively according to the element analysis. The IR spectrum showed that the substitutive position was N,O-substitution, and the 13C-NMR spectrum showed that substitutive position of carboxymethylchitin was mostly primary substitution of 6-OH, and according to the substitutive proportion, the substitutive turns were in the following decreasing order: 6-OH, NH2, and 3-OH. The weightaveraged and the numberaveraged molecular weights and polydispersity were 6.25×105, 5.60×105 and 1.22, respectively. The results from the biological property test showed that carboxymethylchitin was a biomaterial that was sterile, pyrogen-free, acute toxicity-free, cytotoxicity-free, intracutaneous irritationfree, skin sensitization-free and biomaterial genotoxicity-free, with no side or adverse effects on the related tissues after implantation into the human body. Conclusion Carboxymethylchitin prepared from chitin by alkalization and etherification is amacromolecule biomaterial that has a low degree of deacetylation, a high degreeof substitution, and a good biocompatibility.
Objective To study the result of using nerve conduit coated with chitin and filled with a guide-fiber to repair peripheral nerve defect. Methods Twenty-four female adult SD rats were made the model of 14 mm-gap on bilateral sciatic nerve under sterile condition. The rats were randomly divided into 4 groups(n=6),group A: polymer polyglycolic-lactic acid(PGLA) nerve conduit coated with chitin and filled with a guide-fiber as experimental group to repair 14 mm gap of rat sciatic nerve；group B: PGLA nerve conduit coated with chitin； group C: PGLA nerve conduit； group D: autograft (control group). The repair result was evaluated by normal observation, EMG testing and S-100 histological immunostaining analysis 4 and 12 weeks after operation.Results Four weeks after the operation，there were new regenerated immature fibers in groups A,B and C, 12 weeks after the operation, the regenerated nerve fibers were seen to have bridged the gap. There were myelinated fibers equably distributed and rarely newgenerated nerve fibers in distal parts of group D. The repair result of PGLA nerve conduit coated with a chitin and filled with guide-fiber was better than that of groups B and C（Plt;0.05）. There was significant difference of nerve fiber diameter，thickness of myelin sheath and fiber density in group D from those in groups A, B and C（Plt;0.05），but there were degenerative changes such as vacuoles insheaths and myelin separation in proximal and few new regenerated nerve fibers in distal parts of group D. Conclusion PGLA nerve conduit coated with chitin and filled with a guide-fiber offers a possible substitute for the repair of peripheral nerve defect.
OBJECTIVE: To study the feasibility of α-cyanoacrylate medical adhesive in fixation of intratemporal facial nerve when nerve was repaired within chitin chamber, and to investigate the nerve regeneration. METHODS: Nerve defect of 6 mm was made in left intratemporal facial nerves of 48 rabbits. All the defects were bridged with chitin chamber and were fixed by α-cyanoacrylate medical adhesive, surgical suture and natural union. Nerve function test and histomorphological examination were carried out at 1 month and 3 months after repair. RESULTS: It was observed that the nerve was fixed firmly to the chamber with no crack or crease by α-cyanoacrylate medical adhesive. The regenerated new nerve fibers were more regular and denser and the neurological function recovered much better in the group fixed by alpha-cyanoacrylate medical adhesive than in the groups those fixed by surgical suture and natural union. CONCLUSION: The medical adhesive is b in adhesion and beneficial to nerve repair; repair of intratemporal facial nerve defect within chitin chamber fixed by alpha-cyanoacrylate medical adhesive is feasible, simple and timesaving.
OBJECTIVE: To evaluate the nerve regeneration after implantation of chitin tubes containing nerve growth factor(NGF) in the rabbit facial nerve. METHODS: Bilateral 8 mm defect of superior buccal divisions of the facial nerves were made in 16 New Zealand rabbits. Chitin tubes containing NGF were implanted into the gaps, and autologous nerves were implanted into the right gaps as control. The nerve regeneration was evaluated with electrophysiological and ultrastructural examination after 8 and 16 weeks of operation. RESULTS: Chitin tubes containing NGF successfully induced the nerve regeneration, regularly arranged myelinated and unmyelinated axons could be observed across the 8 mm gaps, and the myelin sheath was thick with clear lamellar structure at 8 weeks after operation, The regenerated nerve fibers increased and were more mature at 16 weeks after operation. There were no significant difference in electrical impulse conduction velocity through the neural regeneration between the experimental and control sides (P gt; 0.05). CONCLUSION: Chitin tubes containing NGF can provide optimal conditions for regeneration of rabbit facial nerve.
In order to study the effect of chitin and chitosan on the growth of Schwann cell (SC) of rats in vitro, the SC was isolated from sciatic nerve and brachial plexus of new-born rats. After the enzymatic and mechanical dissociation, the cell suspension was vaccinated on chitin membrane and chitosan fluid-coated glass coverslips. Then, the growth of SC was examined at 1, 3, 7 days after culture under light microscope and scanning electron microscope. The results showed that 94 percent of the cell grown from was SC and only 6% was fibroblast (FB), while that of the control SC 71% and FB 29% in population. The number of SC in chitosan suspension was more than that in chitin. Therefore, the conclusion was that the chitin and chitosan was histocompatible to SC, and chitosan suspension was superior to chitin, and both could inhibit the growth of fibroblast.
The biomaterial, chitin, was used to create a nerve regeneration chamber for bridging healing experiment of sciatic nerve of rats having a defect of 12mm. The crude Schwann cells were introduced into the chambers in one group and the other group had no crude Schwann cells in the chamber and the results of the two groups were compared with those having the nerve defects bridged with skeletal muscles. The specimens were observed by macroscopic, microdissection. electrophysiologic testing, HRP retrograde labelling, histologic and electron microscopic examinations at 4, 8, and 12 weeks after the operation. The results showed that atthe 8th week, the regenerating nerve fibers from the cephalad ends had united with the fibers of the caudal ends of the divided nerves either the crude Schwanneclls were introduced or not, but the morphology of the regenerating nerve, the way of regeneration and the recovery of the function of the extremities were far superior in the group that no cruds Schwann cells had been introduced than those with crude Schwann cell introduced and those bridged by skeletal muscles.
In this experiment, two proximal ends of themedian and ulnar nerves of rabbit wereapproxirnated within the chitin tube for thepurpose to inhibit the neuroma formation. Byobservation under light and transmission electronmicrnscopo and immunohistochemistry, wefound that: (1) the axons of the two proximalstumpe could regenerate in the chitin tube for 2to 5mm, and then ceased to grow when anaxonal overlap happened resulting in inhibitingneuroma formation; (2) chitin tube could bedegradated a...
Thiry wistar rats were used and divided in 2 groups. A segment of 6mm was excised in the sciatic nerve which were then bridged with chitin and skelal muscle. at 4,8,12 weeks after operation, In the chitin group a satisfactory regeneration of nerve fibers was evident with electrophysiologic and histologic examinations, and HRP retrogade labelling evaluation. The possible mechanism of enhancing nerve regeneration of chitin was also discussed.
The chitin abstracted from silkworm chrysalis was subjected to toxicological study including: (1)systematic toxicological test, (2)pyretogenic test, (3)primary cutaneous irritative test, (4)intradermal injection test, (5)cutaneous allergic test. (6)conjunctival irritative test, (7)hemolysis test, (8)bacterial toxicity test, (9)dominant lethal test, and (10)mutagenetictest. The results showed that chitin is atoxic, non-irritative, non-allergenic, nonpyretogenic, non-hemolytic, non-mutagenic, and non-lethal mutagenic. Therefore, chitin is a compatible biomaterial for implanting into the tissue.
ObjectiveTo systematically review the association between the level of plasma YKL-40 and obstructive sleep apnea hypopnea syndrome (OSAHS).MethodsWe searched PubMed, EMbase, MEDLINE, CNKI, WanFang Data, VIP database and supplemented by Google academic retrieval to collect case-control studies about the association between the level of plasma YKL-40 and OSAHS from inception to April 2017. Two reviewers independently screened literature, extracted data and evaluated the risk of bias of included studies. And then, meta-analysis was performed by RevMan 5.3 software.ResultsA total of 5 case-control studies were included, involving 755 OSAHS patients and control population. The results of meta-analysis showed that the level of plasma YKL-40 in OSAHS patients was higher than that in control group (SMD=1.20, 95%CI 0.33 to 2.06, P=0.007). The subgroup analysis showed that the level of plasma YKL-40 in OSAHS patients from Asia was significantly higher than that in control group (SMD=1.79, 95%CI 0.83 to 2.75, P=0.000 2). The comparison between different severity of OSAHS showed that the wild-medium group had lower plasma level of YKL-40 than the severe group (SMD=–0.83, 95%CI –1.46 to –0.19, P=0.01).ConclusionYKL-40 may play an important role in the pathogenesis of OSAHS. Due to limited quantity and quality of the included studies, more high quality studies are needed to verify above conclusions.