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The diagnosed COVID-19 cases revealed that the incubation periods (IP) varied a lot among patients. However, few studies had emphasized on the different clinical features and prognosis of patients with different IP. A total of 330 patients with laboratory-confirmed COVID-19 were enrolled and classified into immediate onset group(IP10 days, L group, 75 cases) based on IP. The difference of clinical characteristics and prognosis of the two groups were compared. There were more patients with fever in I group than in L group(P = 0.003), and counts of all the total lymphocytes, total T lymphocytes, CD4 + and CD8 + T lymphocytes were significantly different between the two groups(all P

With the development of minimally invasive techniques, injectable materials have become one of the major hotspots in the biomaterial field. We have developed an injectable bone regeneration composite (IBRC) using calcium alginate hydrogel as matrix to carry nano-hydroxyapatite/collagen particles. In this work, we evaluated the homogeneity of IBRC by dry/wet weight ratio test. The results showed that the structural homogeneity was determined by controlling the molar ratios of trisodium phosphate to calcium sulfate rather than alginate concentration in the studied ranges. Pore sizes of wet IBRC samples were characterized by thermoporometry. The pore properties of dried IBRC were tested by mercury porosimetry. Average pore size and porosity of dried IBRC declined with increasing alginate concentration. In contrast, surprisingly, pore size of wet homogeneous IBRC increased with increasing alginate concentration. Meanwhile, the swelling ratio did not increase with varying alginate concentration, but the swelling degree increased with increasing alginate concentration. In vitro cell culture showed that IBRC had no obvious cytotoxic effect on the rat bone mesenchymal stem cells. The morphology and viability of cells were also related to MR value. IBRC had good histocompatibility with a mild short-term inflammatory response in rat dorsum muscle. In addition, the excellent ability of IBRC to promote bone healing was confirmed by 5-mm-diameter cranial defects using histological analysis and bone mineral density measurement.