BACKGROUND:Endothelin has been found to be involved in the breakdown of the blood-spinal cord barrier after spinal cord injury,and stem cell-derived exosomes can reduce the permeability of the blood-spinal cord barrier and repair spinal cord injury. OBJECTIVE:To investigate whether exosomes produced by human umbilical cord mesenchymal stem cells can reduce the permeability of the blood-spinal cord barrier by inhibiting endothelin-1 expression,thus repairing spinal cord injury. METHODS:Exosomes were extracted from the cultured supernatant by the hyperspeed centrifugation method.The morphology of exosomes was observed by transmission electron microscope.The expression levels of tsg101 and CD63 were detected by western blot assay.Eighty SD rats were randomly divided into sham operation group,model group,exosome group,and endothelin-1 group(n=20).The modified Allen's method was used to create the rat model of spinal cord injury.In the endothelin-1 group,10 μL(1 μg/mL)endothelin-1 was injected directly into the injured area with a microsyringe.Immediately,1 day,2 days after operation,sham operation group and model group were injected with 200 μL PBS solution through the tail vein;the exosome group and endothelin-1 group were injected with 200 μL exosome(200 μg/mL)solution through the tail vein,respectively.Hind limb motor function scores were performed on days 1,3,7,14 and 21 after spinal cord injury.The blood-spinal cord barrier permeability was observed by Evans blue staining on day 7 after injury.The expression levels of tight junction proteins β-Catenin,ZO-1,Occludin and endothelin-1 in the spinal cord were detected by western blot assay. RESULTS AND CONCLUSION:(1)Basso-Beattie-Bresnahan score in the exosome group was significantly higher than that in the model group at 3-21 days after injury(P<0.05).Hematoxylin-eosin staining showed that spinal cord injury was greatly reduced in the exosome group compared with the model group.Basso-Beattie-Bresnahan score in the endothelin-1 group was significantly decreased compared with the exosome group(P<0.05).Spinal cord injury was more severe in the endothelin-1 group than that in the exosome group.(2)The expression of endothelin-1 in the model group was significantly increased compared with the sham operation group(P<0.05),and the expression of endothelin-1 in the exosome group was significantly decreased compared with the model group(P<0.05).(3)The blood-spinal cord barrier Evans blue exudate in the exosome group was significantly decreased compared with the model group(P<0.05).The expression levels of the tight junction proteins β-Catenin,Occludin and ZO-1 in the exosome group were increased(P<0.05);the Evans blue exudate in the endothelin-1 group was significantly increased compared with the exosome group(P<0.05).The expression level of tight junction protein was significantly decreased compared with the exosome group(P<0.05).(4)The results show that human umbilical cord mesenchymal cell-derived exosomes protect the permeability of the blood-spinal cord barrier by down-regulating the expression of endothelin-1 and play a role in the repair of spinal cord injury.

Objective:It explores critical issues of discounting in health technology assessment to provide a reference for improving discount rates in China.Methods:Based on literature review and empirical cases,it compares and analyzes the practical experience of the UK and Canada and the basis for discount rate setting in pharmacoeconomic evaluation and guidelines of various countries.Results:It is found that the social time preference and social opportunity cost approach provide research perspectives for discount rate calculation.How-ever,there are differences in the choice of discounting in international guidelines and pharmacoeconomic evaluation practices,which may reflect differences among countries regarding economic environment,healthcare systems,and values.Conclusion:It calls for more basic research on discounting and suggests the formulation of discount rates that align with our China's economic environment to provide deci-sion-makers with a reliable information foundation.

Objective:It explores critical issues of discounting in health technology assessment to provide a reference for improving discount rates in China.Methods:Based on literature review and empirical cases,it compares and analyzes the practical experience of the UK and Canada and the basis for discount rate setting in pharmacoeconomic evaluation and guidelines of various countries.Results:It is found that the social time preference and social opportunity cost approach provide research perspectives for discount rate calculation.How-ever,there are differences in the choice of discounting in international guidelines and pharmacoeconomic evaluation practices,which may reflect differences among countries regarding economic environment,healthcare systems,and values.Conclusion:It calls for more basic research on discounting and suggests the formulation of discount rates that align with our China's economic environment to provide deci-sion-makers with a reliable information foundation.

Objective:It explores critical issues of discounting in health technology assessment to provide a reference for improving discount rates in China.Methods:Based on literature review and empirical cases,it compares and analyzes the practical experience of the UK and Canada and the basis for discount rate setting in pharmacoeconomic evaluation and guidelines of various countries.Results:It is found that the social time preference and social opportunity cost approach provide research perspectives for discount rate calculation.How-ever,there are differences in the choice of discounting in international guidelines and pharmacoeconomic evaluation practices,which may reflect differences among countries regarding economic environment,healthcare systems,and values.Conclusion:It calls for more basic research on discounting and suggests the formulation of discount rates that align with our China's economic environment to provide deci-sion-makers with a reliable information foundation.

Objective:It explores critical issues of discounting in health technology assessment to provide a reference for improving discount rates in China.Methods:Based on literature review and empirical cases,it compares and analyzes the practical experience of the UK and Canada and the basis for discount rate setting in pharmacoeconomic evaluation and guidelines of various countries.Results:It is found that the social time preference and social opportunity cost approach provide research perspectives for discount rate calculation.How-ever,there are differences in the choice of discounting in international guidelines and pharmacoeconomic evaluation practices,which may reflect differences among countries regarding economic environment,healthcare systems,and values.Conclusion:It calls for more basic research on discounting and suggests the formulation of discount rates that align with our China's economic environment to provide deci-sion-makers with a reliable information foundation.

Objective:It explores critical issues of discounting in health technology assessment to provide a reference for improving discount rates in China.Methods:Based on literature review and empirical cases,it compares and analyzes the practical experience of the UK and Canada and the basis for discount rate setting in pharmacoeconomic evaluation and guidelines of various countries.Results:It is found that the social time preference and social opportunity cost approach provide research perspectives for discount rate calculation.How-ever,there are differences in the choice of discounting in international guidelines and pharmacoeconomic evaluation practices,which may reflect differences among countries regarding economic environment,healthcare systems,and values.Conclusion:It calls for more basic research on discounting and suggests the formulation of discount rates that align with our China's economic environment to provide deci-sion-makers with a reliable information foundation.

Objective:It explores critical issues of discounting in health technology assessment to provide a reference for improving discount rates in China.Methods:Based on literature review and empirical cases,it compares and analyzes the practical experience of the UK and Canada and the basis for discount rate setting in pharmacoeconomic evaluation and guidelines of various countries.Results:It is found that the social time preference and social opportunity cost approach provide research perspectives for discount rate calculation.How-ever,there are differences in the choice of discounting in international guidelines and pharmacoeconomic evaluation practices,which may reflect differences among countries regarding economic environment,healthcare systems,and values.Conclusion:It calls for more basic research on discounting and suggests the formulation of discount rates that align with our China's economic environment to provide deci-sion-makers with a reliable information foundation.

Objective:It explores critical issues of discounting in health technology assessment to provide a reference for improving discount rates in China.Methods:Based on literature review and empirical cases,it compares and analyzes the practical experience of the UK and Canada and the basis for discount rate setting in pharmacoeconomic evaluation and guidelines of various countries.Results:It is found that the social time preference and social opportunity cost approach provide research perspectives for discount rate calculation.How-ever,there are differences in the choice of discounting in international guidelines and pharmacoeconomic evaluation practices,which may reflect differences among countries regarding economic environment,healthcare systems,and values.Conclusion:It calls for more basic research on discounting and suggests the formulation of discount rates that align with our China's economic environment to provide deci-sion-makers with a reliable information foundation.

Objective:It explores critical issues of discounting in health technology assessment to provide a reference for improving discount rates in China.Methods:Based on literature review and empirical cases,it compares and analyzes the practical experience of the UK and Canada and the basis for discount rate setting in pharmacoeconomic evaluation and guidelines of various countries.Results:It is found that the social time preference and social opportunity cost approach provide research perspectives for discount rate calculation.How-ever,there are differences in the choice of discounting in international guidelines and pharmacoeconomic evaluation practices,which may reflect differences among countries regarding economic environment,healthcare systems,and values.Conclusion:It calls for more basic research on discounting and suggests the formulation of discount rates that align with our China's economic environment to provide deci-sion-makers with a reliable information foundation.

ObjectiveTo investigate the application of endoscopy in obtaining the great saphenous vein （GSV） during coronary artery bypass grafting （CABG） and explore the learning curve， with a particular focus on common challenges encountered during the learning process and their impact on early clinical outcomes. MethodsA retrospective analysis was conducted on clinical data from 83 patients who underwent off-pump CABG with endoscopic GSV harvesting at the First Affiliated Hospital of Zhengzhou University from July 2013 to April 2014. Patients were categorized into four groups based on the chronological order of their hospitalization： Group A （novice group， n=20）， Group B （proficient group， n=20）， Group C （progressive group， n=20）， and Group D （mature group， n=23）. Differences in perioperative and midterm follow-up outcomes among the groups were analyzed to determine the learning curve period. ResultsThe study population had a mean age of （60.22±8.06） years and a mean body weight of （69.77±11.66） kg. Comorbidities included hypertension （24 cases）， diabetes （26 cases）， and subacute cerebral infarction （14 cases）. The novice group exhibited significantly shorter GSV length-to-harvest time ratio relative to the other three groups （P<0.001） and a significantly higher incidence of main vein damage （P=0.006）. However， there was no statistically significant difference in graft patency at the 1-year follow-up. ConclusionThorough and reliable technical training in endoscopic GSV harvesting is essential to minimize vascular injury caused by novice operators. Approximately 20 cases of hands-on experience and a careful self-analysis of procedural challenges are likely required to achieve proficiency in GSV harvesting.