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OBJECTIVE@#To determine the environmental contamination degree of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in corona virus disease 2019 (COVID-19) wards, to offer gui-dance for the infection control and to improve safety practices for medical staff, by sampling and detecting SARS-CoV-2 nucleic acid from the air of hospital wards, the high-frequency contact surfaces in the contaminated area and the surfaces of medical staff's protective equipment in a COVID-19 designated hospital in Wuhan, China.@*METHODS@#From March 11 to March 19, 2020, we collected air samples from the clean area, the buffer room and the contaminated area respectively in the COVID-19 wards using a portable bioaerosol concentrator WA-15. And sterile premoistened swabs were used to sample the high-frequency contacted surfaces in the contaminated area and the surfaces of medical staff's protective equipment including outermost gloves, tracheotomy operator's positive pressure respiratory protective hood and isolation clothing. The SARS-CoV-2 nucleic acid of the samples were detected by real-time fluorescence quantitative PCR. During the isolation medical observation period, those medical staff who worked in the COVID-19 wards were detected for SARS-CoV-2 nucleic acid with oropharyngeal swabs, IgM and IgG antibody in the sera, and chest CT scans to confirm the infection status of COVID-19.@*RESULTS@#No SARS-CoV-2 nucleic acid was detected in the tested samples, including the 90 air samples from the COVID-19 wards including clean area, buffer room and contaminated area, the 38 high-frequency contact surfaces samples of the contaminated area and 16 surface samples of medical staff's protective equipment including outermost gloves and isolation clothing. Moreover, detection of SARS-CoV-2 nucleic acid by oropharyngeal swabs and IgM, IgG antibodies in the sera of all the health-care workers who participated in the treatment for COVID-19 were all negative. Besides, no chest CT scan images of medical staff exhibited COVID-19 lung presentations.@*CONCLUSION@#Good ventilation conditions, strict disinfection of environmental facilities in hospital wards, guidance for correct habits in patients, and strict hand hygiene during medical staff are important to reduce the formation of viral aerosols, cut down the aerosol load, and avoid cross-infection in isolation wards. In the face of infectious diseases that were not fully mastered but ma-naged as class A, it is safe for medical personnel to be equipped at a high level.
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Humans , Betacoronavirus , COVID-19 , China , Coronavirus Infections , Medical Staff , Pandemics , Pneumonia, Viral , Protective Devices , SARS-CoV-2 , Severe Acute Respiratory Syndrome/prevention & controlABSTRACT
Objective: To investigate the effect of cartilage tissue engineering scaffold PVA/ι-CA on the biological behavior of the ATDC-5 cells,and to evaluate its feasibility on constructing tissue engineering cartilage. Methods:The polyvinyl alcohol (PVA)and carrageenan were used to make the composite scaffold material PVA/ι-CA according to a certain proportion by physical blending technology and repeated freezing thawing method,and the porosity and pore size of PVA/ι-CA were detected.The ATDC-5 cells were seeded into the composite scaffold and its growth was observed; the expressions of collagen type Ⅱ in the ATDC-5 cells were tested by immunohistochemical staining and immunofluorescence staining; the morphology of the ATDC-5 cells was confirmed by Toluidine blue staining.The growth and secretion of extracellular matrix of the ATDC-5 cells were observed under scanning electron microscope (SEM);the proliferative rates of ATDC-5 cells in composite scaffold materials in negative control group (added with DMEM culture media)and experimental group (added with DMEM contain scaffold)were determined by MTT assay.The composite scaffolds were implanted subcutaneously in the SD rats.The histocompatibility and vascularization in vivo of the composite scaffolds were evaluated.Results:The average porosity of cartilage tissue engineering scaffold PVA/ι-CA was (86.88±3.88)%,and the average pore size was 20-40 μm.The HE staining results showed that the ATDC-5 cells grew well with the polygon and plumpness morphology. All the samples were stained positive for collagen type Ⅱ by immunohistochemistry and immunofluorescence staining,which verified the normal phenotype of chondrocytes on the scaffolds. All the sample were stained positive for toluidine blue staining,which verified ECM deposition of the ATDC-5 cells on the scaffolds.The number of the positive cells was significantly increased with the prolongation of time.After cultured for 7 d,few of the ATDC-5 cells presented polygonal;after cultured for 14 d,the ATDC-5 cells distributed more densely,and contacted with each other on the scaffold;after cultured for 21 - 28 d,the ATDC-5 cells filled the interconnected pores of the scaffolds,synthesizing a significant amount of neo-formed ECM.The proliferation of ATDC-5 cells in PVA/ι-CA grew fast during 7-14 d,and it became slow during 21-28 d;the difference was not statistically significant compared with control group (P >0.05).The subcutaneous implantation results showed the inflammatory reactions were slight at the early stage and eviated gradually,there was an increasing angiogenesis at the late stage,and the degradation and absorption of the meterial were slight.Conclusion:PVA/ι-CA composite material will be an ideal material for the cartilage tissue engineering.
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BACKGROUND:Polyvinyl alcohol (PVA) hydrogel with similar porous structure and mechanical properties to the natural cartilage is very suitable for the repair of articular cartilage. However, the pure PVA hydrogel after lyophilization wil be accompanied by the shrinkage of the polymer network and the col apse of the pores, leading to the inhomogeneous performance of the material even in the state of re-swel ing. Addition of the active polymer wil increase the cel adhesion ability of PVA hydrogel. OBJECTIVE:To construct PVA/lota-carrageenan (l-CA) composite materials with different mass fractions of l-CA and evaluate the biocompatibility with vascular endothelial cel s. METHODS:PVA/l-CA composite films with different contents of l-CA were fabricated and then co-cultured with vascular endothelial cel s. Attachment, proliferation and morphological changes of vascular endothelial cel s on the composite were observed by scanning electron microscope and MTT assay to evaluate its biocompatibility. PVA/l-CA three-dimensional scaffold with different contents of l-CA were constructed, and hemolysis experiment was conducted according to the biological evaluation standards of medical devices, and the porosity and pore size were observed using scanning electron microscope. RESULTS AND CONCLUSION:In vitro experimental results showed that the addition of l-CA could significantly increase the biological activity of PVA hydrogel, and promote the cel attachment and proliferation on the scaffold. The hemolysis rate of each experimental group was less than 5%(the accepted safety standard), suggesting that the composite materials were in accordance with the standard of medical devices for hemolysis experiment. These findings indicate that the composite scaffolds with 20%-30%l-CA possess the pore size suitable for cel growth and proliferation and the porosity beneficial for transportation of nutrients and metabolites, which can serve as an excel ent scaffold for tissue engineering.
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Objective To construct novel 3-D composite bionic network and evaluate the histocompatibility . Meth?ods The novel 3-D composite bionic network was prepared from chitosan, hydroxyapatite, gelatin and pectin in certain ra?tio by biomimtic approach, which was co-cultured with MC3T3-E1. The cell compatibility was studied by using inverted phase contrast microscope, routine paraffin section staining, scanning electron microscopy and F-DA staining. The resultant scaffold material was implanted into the dorsal subcutaneous space of SD rats. The histocompatibility, blood vessel capabili?ties and the degradation of the material were observed 2, 4, 8 and 12 weeks after surgery. Results The structure of novel 3-D composite bionic network was three-dimensional and porous. The cells attached on scaffolds attached and grew well with polygonal or fusiform form. It was found that inflammatory reactions were alleviated gradually in the early stage . There was an increasing angiogenesis at late stage. Materials degraded and absorbed more slowly. Conclusion The present study sug?gests that the novel 3-D composite bionic network has good histocompatibility with easy vascularization, and will be a candi?date scaffold for bone tissue engineering.