Graphene oxide-composited chitosan scaffold contributes to functional recovery of injured spinal cord in rats

The study illustrates that graphene oxide nanosheets can endow materials with continuous electrical conductivity for up to 4 weeks. Conductive nerve scaffolds can bridge a sciatic nerve injury and guide the growth of neurons;however, whether the scaffolds can be used for the repair of spinal cord nerve injuries remains to be explored. In this study, a conductive graphene oxide composited chitosan scaffold was fabricated by genipin crosslinking and lyophilization. The prepared chitosan-graphene oxide scaffold presented a porous structure with an inner diameter of 18–87 μm, and a conductivity that reached 2.83 mS/cm because of good distribution of the graphene oxide nanosheets, which could be degraded by peroxidase. The chitosan-graphene oxide scaffold was transplanted into a T9 total resected rat spinal cord. The results show that the chitosan-graphene oxide scaffold induces nerve cells to grow into the pores between chitosan molecular chains, inducing angiogenesis in regenerated tissue, and promote neuron migration and neural tissue regeneration in the pores of the scaffold, thereby promoting the repair of damaged nerve tissue. The behavioral and electrophysiological results suggest that the chitosan-graphene oxide scaffold could significantly restore the neurological function of rats. Moreover, the functional recovery of rats treated with chitosangraphene oxide scaffold was better than that treated with chitosan scaffold. The results show that graphene oxide could have a positive role in the recovery of neurological function after spinal cord injury by promoting the degradation of the scaffold, adhesion, and migration of nerve cells to the scaffold. This study was approved by the Ethics Committee of Animal Research at the First Affiliated Hospital of Third Military Medical University(Army Medical University)(approval No. AMUWEC20191327) on August 30, 2019.

The comparisons on total RNA from different source-original neurons applied in LMPC

Objective To compare the quality and quantity of total RNA from different source-original neurons applied in LMPC technique. Methods （ 1 ） Aglient 2100 bioanalyzer and RT-PCR were used to check the concentration and fragmentation of total RNA from unfixed, temporal fixed and fixed 12 h hypothalamus sections; （2）Different neurons of PVN and SON were collected by LMPC, CRH, TRH, AVP, OT mRNA level were measured by RT-PCR; （3）Labeled neurons by injecting CTB into stomach and non-labeled neurons in DMV collected by LMPC were checked for house keeping genes by RT-PCR. Results （ 1 ） Unfixed section had higher concentration and better quality of total RNA compared with fixed sections applied in LMPC ; relative short amplicons such as GAPDH, NSE, MCH and MCAR were successfully obtained from fixed and unfixed and long amplicon of GR can only be obtained from unfixed material; （2） In magnocellular PVN and SON the expressions of AVP and OT were more special than those in the parvocellular PVN. Oppositely, the expressions of CRH, TRH in the parvocellular were more special than the other two ; （3） The expressions of house keeping genes had no significant difference between labeled and non-labeled DMV neurons. Conclusion The quality and quantity of total RNA from unfixed brain tissues were better than fixed tissues applied in LMPC and the CTB tracer which may differentiate neurons had no significant effect on physiology of the neurons applied in LMPC. The results showed that the LMPC technique is suitable for the qualitative and quantitative study on individual neurons at mRNA level.

Enzymes activity of intestinal grafts after liver small bowel transplantation in rats

OBJECTIVES: To investigate the activity alterations of enzymes in intestine grafts after liver/small bowel transplantation in rats and the relations of these changes to immune rejection of grafts. METHODS: A model of liver/small bowel transplantation (LSBT) was established in closed colony SD and Wistar rats. The activity of enzymes including triphosphatase (ATPase), alkalinophosphatase (AKP), acytelcholinesterase (AchE), oxidesynthase (NOS) and monoamine oxidase (MAO) in bowel grafts was studied histochemically at regular postoperative intervals. RESULTS: The activity of enzymes in the wall of the grafts disappeared eventually in isolated small bowel transplantation (SBT) rats. In contrast, the activity in LSBT rats remained and recovered postoperatively. CONCLUSIONS: The rejection in grafted intestine could be prevented or delayed in LSBT rats. The changes in the activity of enzymes and neurons might be used to detect the rejection and function of the graft.

Conducting polypyrrole in tissue engineering applications

Polypyrrole （PPy）, the earliest prepared conducting polymer, has good biocompatibility, easy synthesis and flexibility in processing. Compared with metal and inorganic materials, doped PPy has better mechanical match with live tissue, resulting in its many applications in biomedical field. This mini-review presents some information on specific PPy properties for tissue engineering applications, including its synthesis, doping, bio-modiflcation. Although some challenges and unanswered problems still remain, PPy as novel biomaterial has promoted the development tissue engineering for its clinical application in the future.

Electrophoretic deposition of Al_(2)O_(3)/ZrO_(2) layer with controllable thickness in ethanol medium

ZrO_(2) toughened Al_(2)O_(3)(Al_(2)O_(3)/ZrO_(2))ceramic layers with required thickness were prepared by electrophoretic deposition(EPD)method using ethanol suspensions with stabilizing agent of polyethyleneimine(PEI)under constant-voltage mode in this paper.The deposition of Al_(2)O_(3)/ZrO_(2) ceramic powders occurred on the titanium alloy cathode.A stable suspension with 1wt% PEI in ethanol at pH 5 was prepared in terms of the zeta potential and sedimentation of the suspension.The effects of the suspension concentration,applied voltage,deposition time and processing method of titanium alloy cathode on the coating thickness and morphology were investigated.The deposition layers on titanium alloys with smooth surfaces and thickness of 0.35–1.2 mm could be obtained by adjusting the aforementioned parameters.In addition,after being sintered at 1500℃ for 3 h in air atmosphere,ZrO_(2) toughened Al_(2)O_(3) ceramic layers became smooth and dense.