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Objective:To effectively express the receptor binding domain (RBD) of SARS-CoV-2 spike protein in Pichia pastoris and to evaluate its immunogenicity. Methods:The gene encoding the RBD protein was synthesized and cloned into the pPICZαA plasmid. After linearization, the plasmid was transferred and integrated into the genome of Pichia pastoris. The expressed RBD protein in culture supernatant was analyzed by Western blot and Biolayer interferometry. After screening, a single clone expressing the RBD protein was selected. The high-level expression of RBD protein was achieved by optimizing the fermentation process, including the salt concentration adjusting of the medium and induction condition optimization (pH, temperature and duration). The immunogenicity of the expressed RBD protein was evaluated in a mouse model. Results:A single clone with a high expression level of RBD protein was obtained and named RBD-X33. The expression level of RBD protein in the fermentation supernatant reached up to 240 mg/L after optimization of the induction condition (HBSM medium, pH=6.5±0.3, 22℃ and 120 h). In the mouse experiment, the recombinant RBD protein was formulated with Alum+ CpG dual adjuvant and injected into mice. The binding IgG antibody levels were up to 2.7×10 6 tested by ELISA and the neutralizing antibody levels were up to 726.8 tested by live virus neutralizing antibody assay (prototype). Conclusions:The RBD protein could be efficiently expressed in Pichia pastoris and induce stronger immune response in animals. This study suggested that the recombinant SARS-CoV-2 RBD protein expressed in Pichia pastoris could serve as a candidate antigen in the development of SARS-CoV-2 vaccine.
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Acute pancreatitis(AP)is one of the common diseases of the digestive system. It can be categorized into mild acute pancreatitis(MAP),moderately severe acute pancreatitis(MSAP)and severe acute pancreatitis(SAP). Early treatment can reduce the incidence of complications and mortality of AP. Biological markers have attracted much attention for their accessibility,high reproducibility and stability. Searching for biological markers with clinical values helps guide the stratified diagnosis and treatment of AP. This article reviewed the advances in study on biological markers for early prediction value of severity of AP.
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Objective To evaluate the effect of plan-do-check-act (PDCA)cycle method in improving disinfection efficacy of object surface in intensive care unit (ICU).Methods On the basis of management of healthcare-associat-ed infection (HAI)and prevention of multidrug-resistant organisms,disinfection efficacy of object surface in an ICU was intervened,data about surface object specimens taken before,during,and after intervention,HAI in patients, as well as detection of MDROs were collected.Results The total qualified rate of specimens taken before,during, and after intervention was 58.24%,76.74%,and 88.71 %,respectively,there was an increased tendency,the difference was significant (χ2 =17.41 ,P =0.009);the incidence of HAI was 3.72%,2.42%,and 1 .78%,respec-tively,there was a decreased tendency(χ2 =6.03,P =0.039),case infection rate was 4.36%,2.75%,and 2.37%respectively,there was a decreased tendency (χ2 = 7.24,P = 0.046 );detection rate of MDROs was 34.03%, 27.45%,and 14.05%,respectively,there was a decreased tendency (χ2 =33.84,P =0.007),the percentage of pa-tients who were detected MDROs and HAI caused by MDROs showed a decreased tendency(χ2 =6.14,6.02,both P<0.05).Conclusion The implementation of PDCA cycle can effectively improve disinfectant efficacy of ICU object surface,and reduce the incidence of MDRO HAI.
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Objective To analyze risk factors and antimicrobial use for hospital-acquired pneumonia (HAP)due to multidrug-resistant organisms (MDROs)in an intensive care unit(ICU),so as to perform risk assessment and guide antimicrobial use.Methods From January 2012 to December 2013,HAP patients were conducted retrospective co-hort study,risk factors for MDRO-HAP and rationality of antimicrobial use were analyzed.Results A total of 110 cases of HAP occurred in ICU,63 cases (57.27%)were MDR-HAP.Logistic regression analysis revealed that re-cent hospital stay ≥5 days (OR=19.94),transference from other hospitals (OR =19.33),infection type of late-onset HAP (OR=7.98),and antimicrobial use in recent 90 days (OR =3.42)were independent risk factors for MDR-HAP.Initial empirical anti-infective treatment revealed that there were no significant difference in timing of antimicrobial administration within 24 hours after clinical diagnosis was confirmed,and rationality of antimicrobial selection between MDR-HAP group and non-MDR-HAP group (both P >0.05);The isolation rate of pathogens in MDR-HAP group was lower than non-MDR-HAP group (73.02% vs 91 .49% P 0.05 );the rationality rate of therapy course in MDR-HAP group was higher than no-MDR-HAP group,but rationality rate of combination use of antimicrobial agents was slightly lower than the latter (both P < 0.05 ).Conclusion Patients in ICU should be conducted risk factor assessment,and according prevention and control measures should be formulated,so as to reduce the occurrence of MDR-HAP,health care workers should standardized the initial empirical anti-infective treatment.
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Objective To compare the myocardial damage in patients with severe valvular heart disease undergoing open heart surgery under propofol and sevoflurane combined anesthesia.Methods Thirty-two patients with severe heart valvular disease undergoing open heart surgery were randomized into 3 groups:midazolam group (group M,n =8),propofol group (group P,n =12) and sevoflurane group (group S,n =12).Midazolam 1-5 mg,vecuronium 0.15 mg/kg and fentanyl 10-20 μg/kg were injected intravenously in group M.Propofol 1-2 mg/kg,vecuronium 0.15 mg/kg and fentanyl 10 μg/kg were injected intravenously in group P.In group S,the patients inhaled sevoflurane until the eyelash reflex disappeared,the end-tidal concentration of sevoflurane was 0.5 ％-2.0％,and vecuronium 0.15 mg/kg and fentanyl 10μg/kg were injected intravenously.The patients were mechanically ventilated after tracheal intubation.Anesthesia was maintained with iv infusion of midazolam 0.1 mg· kg-1 · h-1,fentanyl 0.2 μg· kg-1 · min-1,and vecuronium 0.12 mg· kg-1 · h-1 in group M,with iv infusion of propofol 150 μg· kg-1 · min-1 and fentanyl μg· kg-1 · min-1 in group P,or with inhalation of 0.5％-2.0％sevoflurane in group S.CPB was established routinely.The concentration of sevoflurane was 0.5 ％-1.0％ during CPB.Venous blood samples were collected before anesthesia (T1),at 20 min and 2 h after aortic unclamping (T2,3),and at 24 h after operation (T4) for determination of the levels of plasma lactic dehydrogenase (LDH),creatine kinase (CK),creatine kinase MB (CK-MB),cardiac troponin Ⅰ (cTnⅠ),superoxide dismutase (SOD)and tumor necrosis factor (TNF)-α.Myocardial tissues were taken at T2 for determination of heme oxygenase-1 (HO-1) expression and for examination of the myocardial ultrastructure.Results Compared with group M,the levels of plasma LDH,CK-MB,and CK were significantly decreased at T2-4,the levels of plasma SOD and cTnⅠ were significantly increased at T2,3,and the expression of HO-1 was up-regulated at T2 in groups P and S,and the levels of plasma TNF-α were significantly decreased at T2-4 in group P and at T2,3 in group S (P ＜ 0.05).The pathologic changes induced by I/R were less severe in groups P and S than in group M.Conclusion Both propofol and sevoflurane can attenuate the myocardial damage in patients with severe valvular heart disease undergoing open heart surgery and the effects are comparable.