Researches on Mesenchymal Stem Cells for Treatment of Spinal Cord Injury: A Visualization Analysis / 中国康复理论与实践

Results and Conclusion A total of 236 authors were included, out of whom 49 authors published more than three papers, and high-yielding authors were mainly represented by Zeng Y S and Chen L. There were 162 countries/institutions involved, out of which 85 published more than three papers. Seventy-five journals were included, out of which Exp Neurol was the one with the most articles. There were 107 key words included, and the hot words were spinal cord injury, MSCs, transplantation, bone marrow, repair, and functional recovery, which formed six cluster groups. The trend was to extract and culture progenitor cells and induce their directional differentiation; mechanism of immune regulation, anti-inflammatory and nerve regeneration in the treatment of spinal cord injury by MSCs, as well as the research of tissue engineering technology, biological materials in this field. Objective:To analyze the research status and hotspots of mesenchymal stem cells (MSCs) for treatment of spinal cord injury in the past five years. Methods:The related literatures from 2014 to 2018 in Science Citation Index-Expanded (SCI-E) of Web of Science (WOS) were included. CiteSpace software was used to analyze the cooperation relationship of authors, countries and research institutions. The keywords were taken as nodes for co-occurrence analysis, cluster analysis, dynamic frontier evolution and burst analysis. The co-citation of journals and literatures were taken as nodes for analysis, meanwhile, the visual maps were drawn and the results were analyzed.

Oxygen-sulfur exchange and the gas-phase reactivity of cobalt sulfide cluster anions with molecular oxygen.

We present here a study of gas-phase reactivity of cobalt sulfide cluster anions Co(m)S(n)(-) with molecular oxygen. Nascent Co(m)S(n)(-) clusters were prepared via a laser ablation source and reacted with oxygen in a fast flow reactor under thermal collision conditions. We chose (18)O2 in place of (16)O2 to avoid mass degeneration with sulfur, and a time-of-flight (TOF) mass spectrometer was used to detect the cluster distributions in the absence and presence of the reactant. It was found that oxygen-sulfur exchange occurs in the reactions for those with specific compositions (CoS)(n)(-) and (CoS)(n)S(-) (n = 2-5) according to a consistent pathway, "Co(m)S(n)(-) + (18)O2 → Co(m)S(n-1)(18)O(-) + S(18)O". Typically, for "Co2S2(-) + (18)O2" we have calculated the reaction coordinates by employing the density functional theory (DFT), where both the oxygen-sulfur exchange and SO molecule release are thermodynamically and kinetically favorable. It is noteworthy that the reaction with molecular oxygen (triplet ground state) needs to overcome a spin excitation as well as a large O-O activation energy. This study sheds light on the activation of molecular oxygen by cobalt sulfides on one hand and also provides insight into the regeneration mechanism of cobalt oxides from the counterpart sulfides in the presence of oxygen gas on the other hand.

Consecutive oxygen-for-sulfur exchange reactions between vanadium oxide cluster anions and hydrogen sulfide.

Vanadium oxide cluster anions Vm(16)On(-) and Vm(18)On(-) were prepared by laser ablation and reacted with hydrogen sulfide (H2S) in a fast flow reactor under thermal collision conditions. A time-of-flight mass spectrometer was used to detect the cluster distributions before and after the interactions with H2S. The experiments suggest that the oxygen-for-sulfur (O/S) exchange reaction to release water was evidenced in the reactor for most of the cluster anions: VmOn(-) + H2S → VmOn-1S(-) + H2O. For reactions of clusters VO3(-) and VO4(-) with H2S, consecutive O/S exchange reactions led to the generation of sulfur containing vanadium oxide cluster anions VO3-kSk(-) (k = 1-3) and VO4-kSk(-) (k = 1-4). Density functional theory calculations were performed for the reactions of VO3-4(-) with H2S, and the results indicate that the O/S exchange reactions are both thermodynamically and kinetically favorable, which supports the experimental observations. The reactions of VmOn(+) cluster cations with H2S have been reported previously (Jia, M.-Y.; Xu, B.; Ding, X.-L.; Zhao, Y.-X.; He, S.-G.; Ge, M.-F. J. Phys. Chem. C 2012, 116, 9043), and this study of cluster anions provides further new insights into the transformations of H2S over vanadium oxides at the molecular level.

Experimental and theoretical study of the reactions between MO2- (M = Fe, Co, Ni, Cu, and Zn) cluster anions and hydrogen sulfide.

Transition metal oxide cluster anions M(m)(18)O(n)(-) (M = Fe, Co, Ni, Cu, and Zn) were prepared by laser ablation and reacted with H2S in a fast flow reactor under thermal collision conditions. A time-of-flight mass spectrometer was used to detect the cluster distributions before and after the interactions with H2S. The experiments reveal a suite of oxygen/sulfur (O/S) exchange and oxygen/sulfydryl (O/SH) exchange reactions. The O/S exchange reaction to release water was evidenced for all of the MO2(-) cluster anions: MO2(-) + H2S → MOS(-) + H2O, whereas the O/SH exchange reaction to derive MOSH(-) and OH species was only observed for reactions of NiO2(-), CuO2(-), and ZnO2(-). Density functional theory calculations were performed for reaction mechanisms of MO2(-) + H2S (M = Fe, Co, Ni, Cu, and Zn). The computational results are generally in good agreement with the experimental results. This gas-phase study provides an insight into the metal dependent reactivity in the removal of H2S over metal oxides.