To determine the dynamic changes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in respiratory and fecal specimens in children with coronavirus disease 2019 (COVID-19). From January 17, 2020 to February 23, 2020, three paediatric cases of COVID-19 were reported in Qingdao, Shandong Province, China. Epidemiological, clinical, laboratory, and radiological characteristics and treatment data were collected. Patients were followed up to March 10, 2020, and dynamic profiles of nucleic acid testing results in throat swabs and fecal specimens were closely monitored. Clearance of SARS-CoV-2 in respiratory tract occurred within two weeks after abatement of fever, whereas viral RNA remained detectable in stools of pediatric patients for longer than 4 weeks. Two children had fecal SARS-CoV-2 undetectable 20 days after throat swabs showing negative, while that of another child lagged behind for 8 days. SARS-CoV-2 may exist in children's gastrointestinal tract for a longer time than respiratory system. Persistent shedding of SARS-CoV-2 in stools of infected children raises the possibility that the virus might be transmitted through contaminated fomites. Massive efforts should be made at all levels to prevent spreading of the infection among children after reopening of kindergartens and schools.

BACKGROUND AND OBJECTIVES: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a newly identified pathogen that mainly spreads by droplets. Most published studies have been focused on adult patients with coronavirus disease 2019 (COVID-19), but data concerning pediatric patients are limited. In this study, we aimed to determine epidemiological characteristics and clinical features of pediatric patients with COVID-19. METHODS: We reviewed and analyzed data on pediatric patients with laboratory-confirmed COVID-19, including basic information, epidemiological history, clinical manifestations, laboratory and radiologic findings, treatment, outcome, and follow-up results. RESULTS: A total of 74 pediatric patients with COVID-19 were included in this study. Of the 68 case patients whose epidemiological data were complete, 65 (65 of 68; 95.59%) were household contacts of adults. Cough (32.43%) and fever (27.03%) were the predominant symptoms of 44 (59.46%) symptomatic patients at onset of the illness. Abnormalities in leukocyte count were found in 23 (31.08%) children, and 10 (13.51%) children presented with abnormal lymphocyte count. Of the 34 (45.95%) patients who had nucleic acid testing results for common respiratory pathogens, 19 (51.35%) showed coinfection with other pathogens other than SARS-CoV-2. Ten (13.51%) children had real-time reverse transcription polymerase chain reaction analysis for fecal specimens, and 8 of them showed prolonged existence of SARS-CoV-2 RNA. CONCLUSIONS: Pediatric patients with COVID-19 presented with distinct epidemiological, clinical, and radiologic characteristics from adult patients. Nearly one-half of the infected children had coinfection with other common respiratory pathogens. It is not uncommon for pediatric patients to have prolonged fecal shedding of SARS-CoV-2 RNA during the convalescent phase.

Carboxymethyl chitosan-graft-polylactide (CMCS-PLA) and carboxymethyl chitosan (CMCS) hydrogels were prepared by using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) as crosslinking agent and catalyst at room temperature. The biocompatibility of the hydrogels was evaluated with the aim of assessing their potential as drug carrier. Various aspects of biocompatibility were considered, including MTT assay, agar diffusion test, release of lactate dehydrogenase (LDH), hemolytic test, plasma recalcification time (PRT), and dynamic clotting time. MTT assay showed that the cytotoxicity level of both hydrogels to L-929 cells was 0 or 1. The LDH release of CMCS and CMCS-PLA was 26 and 29%, respectively, which is slightly higher than that of the negative control (21%) and much lower than that of the negative control (87%). The hemolysis ratio of CMCS and CMCS-PLA was 1.4 and 1.7%, respectively, suggesting outstanding anti-hemolysis properties of both materials. The PRT value of CMCS and CMCS-PLA was higher by 77 and 99% than the value of the positive control. All the results revealed that the hydrogels present good cytocompatibility and hemocompatibility in vitro. In vivo degradation and tissue compatibility were evaluated by subcutaneous injection in the dorsal area of rats. CMCS and CMCS-PLA hydrogels were completely degraded and the inflammatory response also completely disappeared around hydrogels after 19 days in vivo. It is thus concluded that hydrogels formed of CMCS and CMCS-PLA with outstanding biocompatibility are promising as potential drug carrier.

Background: With the ongoing outbreak of Coronavirus Disease 2019 (COVID-19), infected patients within and beyond the epidemic area, Wuhan, China, showed different epidemiological and clinical characteristics. There is a paucity of data concerning coinfection with other common respiratory pathogens in COVID-19 patients outside of Wuhan. Methods: We conducted a double-centre study recruiting 68 patients with severe acute respiratory coronavirus 2 (SARS-CoV-2) infection confirmed by nucleic acid testing in Qingdao and Wuhan from January 17 to February 16, 2020. Indirect immunofluorescence was performed to detect the specific IgM antibody against common respiratory pathogens in collected acute phase serum. Results: Of the 68 patients with SARS-CoV-2 infection, 30 (44.12%) were from Qingdao. The median age of Qingdao and Wuhan patients were 50 (IQR: 37-59) and 31 (IQR: 28-38) years, respectively, and the majority of patients were female in Qingdao (60.00%) and Wuhan (55.26%). Among COVID-19 patients in Qingdao, 24 (80.00%) of them had IgM antibodies against at least one respiratory pathogen, whereas only one (2.63%) of the patients in Wuhan had positive results for serum IgM antibody detection ( P <0.0001). The most common respiratory pathogens detected in Qingdao COVID-19 patients were influenza virus A (60.00%) and influenza virus B (53.33%), followed by mycoplasma pneumoniae (23.33%) and legionella pneumophila (20.00%). While the pattern for coinfection in patients with community-acquired pneumonia in Qingdao was quite different, with a positive rate of only 20.90%. Interpretation: We reported a large proportion of COVID-19 patients with coinfection of seasonal respiratory pathogens in Qingdao, northeast China, which differed greatly from the patients in Wuhan, central China. Precautions are needed when dealing with COVID-19 patients beyond the epidemic centre who have coinfection with other respiratory pathogens. We highly recommend adding SARS-CoV-2 to routine diagnostic testing in capable hospitals to prevent misdetection of the virus.

The Wnt family is a large class of highly conserved cysteine-rich secretory glycoproteins that play a vital role in various cellular and physiological courses through different signaling pathways during embryogenesis and tissue homeostasis 3. Wnt5a is a secreted glycoprotein that belongs to the noncanonical Wnt family and is involved in a wide range of developmental and tissue homeostasis. A growing body of evidence suggests that Wnt5a affects embryonic development, signaling through various receptors, starting with the activation of β-catenin by Wnt5a. In addition to affecting planar cell polarity and Ca²⁺ pathways, β-catenin also includes multiple signaling cascades that regulate various cell functions. Secondly, Wnt5a can bind to Ror receptors to mediate noncanonical Wnt signaling and a significant ligand for Ror2 in vertebrates. Consistent with the multiple functions of Wnt5A/Ror2 signaling, Wnt5A knockout mice exhibited various phenotypic defects, including an inability to extend the anterior and posterior axes of the embryo. Numerous essential roles of Wnt5a/Ror2 in development have been demonstrated. Therefore, Ror signaling pathway become a necessary target for diagnosing and treating human diseases. The Wnt5a- Ror2 signaling pathway as a critical factor has attracted extensive attention.