Age-dependent decrease of circulating T follicular helper cells correlates with disease severity in elderly patients with COVID-19.

Overwhelming evidence has shown that aging is a significant risk factor for COVID-19-related hospitalizations, death and other adverse health outcomes. Particular T cell subsets that susceptible to aging and associated with COVID-19 disease severity requires further elucidation. Our study recruited 57 elderly patients with acute COVID-19 and 27 convalescent donors. Adaptive immunity was assessed across the COVID-19 severity spectrum. Patients underwent age-dependent CD4+ T lymphopenia, preferential loss of circulating T follicular regulatory cells (cTfh) subsets including cTfh-em, cTfh-cm, cTfh1, cTfh2, cTfh17 and circulating T follicular regulatory cells (cTfr), which regulated antibody production through different pathways and correlated with COVID-19 severity, were observed. Moreover, vaccination improved cTfh-cm, cTfh2, cTfr proportion and promoted NAb production. In conclusion, the elderly had gone through age-dependent cTfh subsets deficiency, which impeded NAb production and enabled aggravation of COVID-19 to critical illness, whereas SARS-CoV-2 vaccine inoculation helped to rejuvenate cTfh, cTfr and intensify NAb responses.

Tactile stimulation promotes the recovery of motor function in rats with cerebral ischaemia.

OBJECTIVES: Tactile stimulation (TS) can promote neurogenesis and motor function recovery in rats with hypoxic-ischaemic brain injury, but the underlying mechanism is not clear. This study aimed to assess the effects of TS on neurological function in rats after cerebral ischaemia and explore the underlying mechanism. METHODS: Adult SD rats were randomly divided into a sham operation (SHAM) group, middle cerebral artery occlusion with tactile stimulation (TS-MCAO) group and middle cerebral artery occlusion with sedentary intervention (SED-MCAO) group. Twenty-four hours after MCAO, rats in the TS-MCAO group received TS for 20 min/d 5 d/w for 4 weeks. Cerebral blood flow (CBF), changes in body weight, behavioural scores, the infarct volume, corticospinal tract integrity, and neurochemical changes were measured, and Golgi-Cox staining, transmission electron microscopy and Western blotting were performed. RESULTS: CBF recovery was improved in the TS-MCAO group compared with the SED-MCAO group. Body weight and behavioural scores in the TS-MCAO group significantly changed after 28 days of intervention. After 14 and 28 days of intervention, the infarct volume decreased significantly, the ratios of fractional anisotropy increased and the ratios of apparent diffusion coefficient decreased, the ratios of Nacetylaspartate (NAA)/creatine (Cr) and glutamate (Glu)/ Cr increased. After 28 days of intervention, the complexity and density of dendrites, the number of synapses and the expression of synaptic plasticity-related proteins increased in the peri-infarct cortex. CONCLUSION: TS can improve motor performance in rats with cerebral ischaemia and the improvement is correlated with synaptic plasticity. This finding would be helpful to provide a rehabilitation program for patients following stroke.

Density functional theory study of C2F5I synthesis over activated carbon catalyst.

Quantum chemistry calculations based on the density functional theory (DFT) are carried out to investigate the reaction mechanism of C2F5I synthesis catalyzed by activated carbon. The possible adsorption configurations of fluorocarbon intermediates are analyzed carefully. Also, the related transition states and reaction pathway are analyzed. According to calculation, firstly, the dehydrofluorination of C2HF5, as the rate-determining step, is catalyzed by the carboxyl acid groups. Secondly, the tetrafluoroethylidene radicals disproportionate on graphite (001) surface instead of rearrangement or dimerization. Next, the fluorine abstractions between fluorocarbon intermediates over graphite (001) surfaces proceed successfully. Finally, the desorbed pentafluoroethyl abstracts iodine atom from molecular iodine spontaneously to afford C2F5I. In adition, our calculations reveal that the carbon deposit in experiment is caused by the fluorine abstraction from fluoroethinyl. The suggested mechanism corresponds with our calculations and available experiments.