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Aims and Objectives To determine the health‐related quality of life (HRQoL) of COVID‐19 patients after discharge and its predicting factors. Background COVID‐19 has caused a worldwide pandemic and led a huge impact on the health of human and daily life. It has been demonstrated that physical and psychological conditions of hospitalised COVID‐19 patients are impaired, but the studies focus on physical and psychological conditions of COVID‐19 patients after discharge from hospital are rare. Design A multicentre follow‐up study. Methods This was a multicentre follow‐up study of COVID‐19 patients who had discharged from six designated hospitals. Physical symptoms and HRQoL were surveyed at first follow‐up (the third month after discharge). The latest multiple laboratory findings were collected through medical examination records. This study was performed and reported in accordance with STROBE checklist. Results Three hundred eleven patients (57.6%) were reported with one or more physical symptoms. The scores of HRQoL of COVID‐19 patients at third month after discharge, except for the dimension of general health, were significantly lower than Chinese population norm ( p < .001). Results of logistic regression showed that female (odds ratio (OR): 1.79, 95% confidence interval (CI): 1.04–3.06), older age (≥60 years) (OR: 2.44, 95% CI: 1.33–4.47) and the physical symptom after discharge (OR: 40.15, 95% CI: 9.68–166.49) were risk factors for poor physical component summary; the physical symptom after discharge (OR: 6.68, 95% CI: 4.21–10.59) was a risk factor for poor mental component summary. Conclusions Health‐related quality of life of discharged COVID‐19 patients did not come back to normal at third month after discharge and affected by age, sex and the physical symptom after discharge. Relevance to clinical practice Healthcare workers should pay more attention to the physical and psychological rehabilitation of discharged COVID‐19 patients. Long‐term follow‐up on COVID‐19 patients after discharge is needed to determine the long‐term impact of COVID‐19.

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Bilayered porous scaffolds have recently attracted interest because of their considerable promise for repairing osteochondral defects. However, determination of optimal pore size in bilayered porous scaffolds remains an important issue. This study investigated the in vivo effects of pore size in bilayered scaffolds using a rabbit model of osteochondral defects. We fabricated five types of integrated bilayered poly(lactide-co-glycolide) (PLGA) scaffolds with different pore sizes in the chondral and osseous layers (50-100 µm, 100-200 µm, 200-300 µm, and 300-450 µm). A subset of bilayered scaffolds seeded with or without allogenic bone marrow mesenchymal stem cells (BMSCs) was implanted in rabbit osteochondral defects. All of the cell/scaffold composite constructs supported the simultaneous regeneration of articular cartilage and subchondral bone, but the best results were observed in cell-seeded PLGA scaffolds with 100-200 µm pores in the chondral layer and 300-450 µm pores in the osseous layer. Our study supports the concept that the effects of pore size on osteochondral repair should be taken into consideration during scaffold design for tissue engineering.

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Poly(lactide-co-glycolide)-bilayered scaffolds with the same porosity or different ones on the two layers were fabricated, and the porosity effect on in vivo repairing of the osteochondral defect was examined in a comparative way for the first time. The constructs of scaffolds and bone marrow-derived mesenchymal stem cells were implanted into pre-created osteochondral defects in the femoral condyle of New Zealand white rabbits. After 12 weeks, all experimental groups exhibited good cartilage repairing according to macroscopic appearance, cross-section view, haematoxylin and eosin staining, toluidine blue staining, immunohistochemical staining and real-time polymerase chain reaction of characteristic genes. The group of 92% porosity in the cartilage layer and 77% porosity in the bone layer resulted in the best efficacy, which was understood by more biomechanical mimicking of the natural cartilage and subchondral bone. This study illustrates unambiguously that cartilage tissue engineering allows for a wide range of scaffold porosity, yet some porosity group is optimal. It is also revealed that the biomechanical matching with the natural composite tissue should be taken into consideration in the design of practical biomaterials, which is especially important for porosities of a multi-compartment scaffold concerning connected tissues.

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Nucleus pulposus (NP) cells experience hyperosmotic stress in spinal discs; however, how these cells can survive in the hostile microenvironment remains unclear. Autophagy has been suggested to maintain cellular homeostasis under different stresses by degrading the cytoplasmic proteins and organelles. Here, we explored whether autophagy is a cellular adaptation in rat notochordal cells under hyperosmotic stress. Hyperosmotic stress was found to activate autophagy in a dose- and time-dependent manner. SQSTM1/P62 expression was decreased as the autophagy level increased. Transient Ca(2+) influx from intracellular stores and extracellular space was stimulated by hyperosmotic stress. Activation of AMPK and inhibition of p70S6K were observed under hyperosmotic conditions. However, intercellular Ca(2+) chelation inhibited the increase of LC3-II and partly reversed the decrease of p70S6K. Hyperosmotic stress decreased cell viability and promoted apoptosis. Inhibition of autophagy led to SQSTM1/P62 accumulation, reduced cell viability, and accelerated apoptosis in notochordal cells under this condition. These evidences suggest that autophagy induction via the Ca(2+)-dependent AMPK/mTOR pathway might occur as an adaptation mechanism for notochordal cells under hyperosmotic stress. Thus, activating autophagy might be a promising approach to improve viability of notochordal cells in intervertebral discs.