Potential application of let-7a antagomir in injured peripheral nerve regeneration

Neurotrophic factors,particularly nerve growth factor,enhance neuronal regeneration.However,the in vivo applications of nerve growth factor are largely limited by its intrinsic disadvantages,such as its short biological half-life,its contribution to pain response,and its inability to cross the blood-brain barrier.Considering that let-7(human miRNA)targets and regulates nerve growth factor,and that let-7 is a core regulator in peripheral nerve regeneration,we evaluated the possibilities of let-7 application in nerve repair.In this study,anti-let-7a was identified as the most suitable let-7 family molecule by analyses of endogenous expression and regulatory relationship,and functional screening.Let-7a antagomir demonstrated biosafety based on the results of in vivo safety assessments and it entered into the main cell types of the sciatic nerve,including Schwann cells,fibroblasts and macrophages.Use of hydrogel effectively achieved controlled,localized,and sustained delivery of let-7a antagomir.Finally,let-7a antagomir was integrated into chitosan conduit to construct a chitosan-hydrogel scaffold tissue-engineered nerve graft,which promoted nerve regeneration and functional recovery in a rat model of sciatic nerve transection.Our study provides an experimental basis for potential in vivo application of let-7a.

Biological characteristics of dynamic expression of nerve regeneration related growth factors in dorsal root ganglia after peripheral nerve injury

The regenerative capacity of peripheral nerves is limited after nerve injury.A number of growth factors modulate many cellular behaviors,such as proliferation and migration,and may contribute to nerve repair and regeneration.Our previous study observed the dynamic changes of genes in L4–6 dorsal root ganglion after rat sciatic nerve crush using transcriptome sequencing.Our current study focused on upstream growth factors and found that a total of 19 upstream growth factors were dysregulated in dorsal root ganglions at 3,9 hours,1,4,or 7 days after nerve crush,compared with the 0 hour control.Thirty-six rat models of sciatic nerve crush injury were prepared as described previously.Then,they were divided into six groups to measure the expression changes of representative genes at 0,3,9 hours,1,4 or 7 days post crush.Our current study measured the expression levels of representative upstream growth factors,including nerve growth factor,brain-derived neurotrophic factor,fibroblast growth factor 2 and amphiregulin genes,and explored critical signaling pathways and biological process through bioinformatic analysis.Our data revealed that many of these dysregulated upstream growth factors,including nerve growth factor,brain-derived neurotrophic factor,fibroblast growth factor 2 and amphiregulin,participated in tissue remodeling and axon growth-related biological processes Therefore,the experiment described the expression pattern of upstream growth factors in the dorsal root ganglia after peripheral nerve injury.Bioinformatic analysis revealed growth factors that may promote repair and regeneration of damaged peripheral nerves.All animal surgery procedures were performed in accordance with Institutional Animal Care Guidelines of Nantong University and ethically approved by the Administration Committee of Experimental Animals,China(approval No.20170302-017)on March 2,2017.

Robust temporal changes of cellular senescence and proliferation after sciatic nerve injury

Cellular senescence and proliferation are essential for wound healing and tissue remodeling.However,senescence-proliferation cell fate after peripheral nerve injury has not been clearly revealed.Here,post-injury gene expression patterns in rat sciatic nerve stumps(SRP113121)and L4–5 dorsal root ganglia(SRP200823)obtained from the National Center for Biotechnology Information were analyzed to decipher cellular senescence and proliferation-associated genetic changes.We first constructed a rat sciatic nerve crush model.Then,β-galactosidase activities were determined to indicate the existence of cellular senescence in the injured sciatic nerve.Ki67 and EdU immunostaining was performed to indicate cellular proliferation in the injured sciatic nerve.Both cellular senescence and proliferation were less vigorous in the dorsal root ganglia than in sciatic nerve stumps.These results reveal the dynamic changes of injury-induced cellular senescence and proliferation from both genetic and morphological aspects,and thus extend our understanding of the biological processes following peripheral nerve injury.The study was approved by the Animal Ethics Committee of Nantong University,China(approval No.20190226-001)on February 26,2019.

One-step green method to prepare progressive burning gun propellant through gradient denitration strategy

Gradiently denitrated gun propellant(GDGP)prepared by a“gradient denitration”strategy is obviously superior in progressive burning performance to the traditional deterred gun propellant.Currently,the preparation of GDGP employed a tedious two-step method involving organic solvents,which hinders the large-scale preparation of GDGP.In this paper,GDGP was successfully prepared via a novelty and environmentally friendly one-step method.The obtained samples were characterized by FT-IR,Raman,SEM and XPS.The results showed that the content of nitrate groups gradiently increased from the surface to the core in the surface layer of GDGP and the surface layer of GDGP exhibited a higher compaction than that of raw gun propellant,with a well-preserved nitrocellulose structure.The denitration process enabled the propellant surface with regressive energy density and good progressive burning performance,as confirmed by oxygen bomb and closed bomb test.At the same time,the effects of different solvents on the component loss of propellant were compared.The result showed that water caused the least component loss.Finally,the stability of GDGP was confirmed by methyl-violet test.This work not only provided environmentally friendly,simple and economic preparation of GDGP,but also confirmed the stability of GDGP prepared by this method.

Role of traditional Chinese medicine in the initiative practice for health

To achieve awareness of the initiative practice for health concept in the Chinese population,traditional Chinese medicine(TCM)doctors should popularize TCM culture and knowledge among young people,people with a low level of education,in low-income populations,and in rural populations.

A Convenient Fluorescent-labeled Assay for in vitro Measurement of DNA Mismatch Repair Activity

Objective The assay of DNA mismatch repair （MMR） activity can be used as a biomarker for environmental condition detection and human disease diagnosis. Radioactive 32p-endlabeled DNA containing mismatch is extensively used as the substrate for MMR activity analyses. The aim of the present study is to develop a simple non-radioactive, but equally specific and sensitive method for the MMR activity assay. Methods A fluorescent label was chosen to replace the radioactive isotope label. Sensitive evaluation of the fluorescent label was carried out for the first time, and then the fluorescent label was compared with the isotope label in the MMR activity and DNA binding assays. Result LOD （limit of detection） of the fluorescent label was about 0.1 fmol and the relative signal strength displayed a pretty good linear relationship. Moreover, the fluorescent label method has equivalent sensitivity and performance as compared with the classical radioactive method in experiments. Conclusion In light of the sensitivity, reproducibility, safety, rapidity and long lifespan of the fluorescent label, this improved method can be applied to evaluation of biologic and toxic effects of environmental pollutants on man and other forms of life.

Intravitreally injected ranibizumab versus photodynamic therapy for CNV secondary to choroidal osteoma:a 7-year follow-up case report

Dear Editor,We present a case of bilateral choroidal neovascularization(CNV)secondary to choroidal osteoma involving the macula and investigate the effect of intravitreal injection of ranibizumab and photodynamic therapy(PDT)in a sevenyear follow-up.Informed consent for patient information and images to be published was obtained from the patient included in the study based on the Declaration of Helsinki,which was approved by the Ethics Committee of Southwest Hospital.