BACKGROUND:In recent years,there has been an explosion of research in the field of physical activity and cognition of older adults,and the research hotspots and topics in this field are constantly evolving.However,a comprehensive review of the literature in this field is lacking. OBJECTIVE:To explore the current international research hotspots and contents in the field of physical activity and cognition of older adults using bibliometrics. METHODS:The Web of Science Core Collection Database,including SCI-EXPANDED,SSCI,A&HCI,CPCI-S,CPCI-SSH,BKCI-S,BKCI-SSH,ESCI,CCR-EXPANDED,IC,etc.,was searched for relevant literature in English.CiteSpace software was used to visualize and analyze 2593 documents collected in the Web of Science database. RESULTS AND CONCLUSION:The evolution of the topics of physical activity and cognition of older adults includes five stages:research on companion robots for older adults,research on the risk of diseases such as dementia,research on cognitive ability and its related ability,research on the relationship between physical activity level and cognitive ability in older adults,and research on different intervention methods and their mechanisms.The research in this field tends to be diversified.On the basis of the research on diseases and cognitive risk reduction,more attention has been paid to the effects of different physical activity modalities on cognition and the related mechanisms,which is the current research hotspot and will be the main research trend in the future.

The present study was designed to analyze the metabolites of all-trans-retinal (atRal) and compare the cytotoxicity of atRal versus its derivative all-trans-retinoic acid (atRA) in human retinal pigment epithelial (RPE) cells. We confirmed that atRA was produced in normal pig neural retina and RPE. The amount of all-trans-retinol (atROL) converted from atRal was about 2.7 times that of atRal-derived atRA after incubating RPE cells with 10 μmol/L atRal for 24 h, whereas atRA in medium supernatant is more plentiful (91 vs. 29 pmol/mL), suggesting that atRA conversion facilitates elimination of excess atRal in the retina. Moreover, we found that mRNA expression of retinoic acid-specific hydroxylase CYP26b1 was dose-dependently up-regulated by atRal exposure in RPE cells, indicating that atRA inactivation may be also initiated in atRal-accumulated RPE cells. Our data show that atRA-caused viability inhibition was evidently reduced compared with the equal concentration of its precursor atRal. Excess accumulation of atRal provoked intracellular reactive oxygen species (ROS) overproduction, heme oxygenase-1 (HO-1) expression, and increased cleaved poly(ADP-ribose) polymerase 1 (PARP1) expression in RPE cells. In contrast, comparable dosage of atRA-induced oxidative stress was much weaker, and it could not activate apoptosis in RPE cells. These results suggest that atRA generation is an antidotal metabolism pathway for atRal in the retina. Moreover, we found that in the eyes of ABCA4^-/-RDH8^-/- mice, a mouse model with atRal accumulation in the retina, the atRA content was almost the same as that in the wild type. It is possible that atRal accumulation simultaneously and equally promotes atRA synthesis and clearance in eyes of ABCA4^-/-RDH8^-/- mice, thus inhibiting the further increase of atRA in the retina. Our present study provides further insights into atRal clearance in the retina.
ATP-Binding Cassette Transporters/physiology* ; Alcohol Oxidoreductases/physiology* ; Animals ; Cell Survival/drug effects* ; Cells, Cultured ; Humans ; Inactivation, Metabolic ; Mice ; Retina/metabolism* ; Retinal Pigment Epithelium/metabolism* ; Swine ; Tretinoin/pharmacology*

Organ preservation fluid could mitigate cold ischemia injury and maintain normal function of the grafts. At present, how to reduce a series of injury caused by cold ischemia of donor liver and improve the preservation quality of grafts are the hot and challenging spots in this field. Currently, preservation fluid in clinical practice has not achieved ideal preservation effect, especially for the protection of marginal donor organs. In the context of severe donor shortage, the key solution is still to explore the optimal preservation protocol for donor liver to prevent grafts from cold ischemia injury. In this article, the mechanism of donor liver injury during cold ischemia, the classification and evolution of donor liver preservation fluid were summarized, the development direction and challenges of donor liver preservation fluid were discussed, aiming to provide novel ideas and references for the research and development of donor liver preservation fluid.