ABSTRACT
The unprecedented coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a serious threat to global public health. Development of effective therapies against SARS-CoV-2 is urgently needed. Here, we evaluated the antiviral activity of a remdesivir parent nucleotide analog, GS441524, which targets the coronavirus RNA-dependent RNA polymerase enzyme, and a feline coronavirus prodrug, GC376, which targets its main protease, using a mouse-adapted SARS-CoV-2 infected mouse model. Our results showed that GS441524 effectively blocked the proliferation of SARS-CoV-2 in the mouse upper and lower respiratory tracts via combined intranasal (i.n.) and intramuscular (i.m.) treatment. However, the ability of high-dose GC376 (i.m. or i.n. and i.m.) was weaker than GS441524. Notably, low-dose combined application of GS441524 with GC376 could effectively protect mice against SARS-CoV-2 infection via i.n. or i.n. and i.m. treatment. Moreover, we found that the pharmacokinetic properties of GS441524 is better than GC376, and combined application of GC376 and GS441524 had a synergistic effect. Our findings support the further evaluation of the combined application of GC376 and GS441524 in future clinical studies. ImportanceSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), which has seriously threatened global public health and economic development. Currently, effective therapies to treat COVID-19 are urgently needed. In this study, we assessed the efficacy of the preclinical inhibitors GC376 and GS441524 using a mouse-adapted SARS-CoV-2 infected mouse model for the first time. Our results showed that low-dose combined application of GC376 and GS441524 could effectively protect mice from HRB26M infection in the upper and lower respiratory tracts. Hence, the combined application should be developed and considered for future clinic practice.
ABSTRACT
Coronaviruses that infect humans belong to the Alpha-coronavirus (including HCoV-229E) and Beta-coronavirus (including SARS-CoV and SARS-CoV-2) genera. In particular, SARS-CoV-2 is currently a major threat to public health worldwide. However, no commercial vaccines against the coronaviruses that can infect humans are available. The spike (S) homotrimers bind to their receptors through the receptor-binding domain (RBD), which is believed to be a major target to block viral entry. In this study, we selected Alpha-coronavirus (HCoV-229E) and Beta-coronavirus (SARS-CoV and SARS-CoV-2) as models. Their RBDs were observed to adopt two different conformational states (lying or standing). Then, structural and immunological analyses were used to explore differences in the immune response with RBDs among these coronaviruses. Our results showed that more RBD-specific antibodies were induced by the S trimer with the RBD in the "standing" state (SARS-CoV and SARS-CoV-2) than the S trimer with the RBD in the "lying" state (HCoV-229E), and the affinity between the RBD-specific antibodies and S trimer was also higher in the SARS-CoV and SARS-CoV-2. In addition, we found that the ability of the HCoV-229E RBD to induce neutralizing antibodies was much lower and the intact and stable S1 subunit was essential for producing efficient neutralizing antibodies against HCoV-229E. Importantly, our results reveal different vaccine strategies for coronaviruses, and S-trimer is better than RBD as a target for vaccine development in Alpha-coronavirus. Our findings will provide important implications for future development of coronavirus vaccines. ImportanceOutbreak of coronaviruses, especially SARS-CoV-2, poses a serious threat to global public health. Development of vaccines to prevent the coronaviruses that can infect humans has always been a top priority. Coronavirus spike (S) protein is considered as a major target for vaccine development. Currently, structural studies have shown that Alpha-coronavirus (HCoV-229E) and Beta-coronavirus (SARS-CoV and SARS-CoV-2) RBDs are in lying and standing state, respectively. Here, we tested the ability of S-trimer and RBD to induce neutralizing antibodies among these coronaviruses. Our results showed that Beta-CoVs RBDs are in a standing state, and their S proteins can induce more neutralizing antibodies targeting RBD. However, HCoV-229E RBD is in a lying state, and its S protein induces a low level of neutralizing antibody targeting RBD. Our results indicate that Alpha-coronavirus is more conducive to escape host immune recognition, and also provide novel ideas for the development of vaccines targeting S protein.
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Objective To evaluate the effects of epinephrine and phenylephrine on evoked potentials in a rat model of acute hemorrhagic shock. Methods Eighteen SPF healthy male Sprague-Dawley rats, aged 11 weeks, weighing 250-350 g, were divided into 3 groups ( n=6 each) using a random number table meth-od: acute hemorrhagic shock group ( HS group) , epinephrine group ( E group) and phenylephrine group ( P group). The animals were anesthetized with intraperitoneal 10％ chloral hydrate 300 mg∕kg and tracheos-tomized, and spontaneous breathing was kept. Acute hemorrhagic shock was induced by withdrawing 40％ of the blood volume from the right internal jugular vein. Epinephrine 2 μg·kg-1 ·min-1 ( 0. 01 mg∕ml, 0. 3 ml) and phenylephrine 20μg·kg-1·min-1 (0. 1 mg∕ml, 0. 3 ml) were intravenously infused after the end of blood letting in E and P groups, respectively. Mean arterial pressure ( MAP ) , somatosensory evoked po-tential (SSEP) and motor evoked potentials (MEP) were recorded before blood letting, at the time of with-drawing 20％of the blood volume, at the end of blood letting, and at 3 min after administration ( at the corre-sponding time point in group HS) . Results The MAP and amplitudes of MEP and SSEP were significantly decreased at the end of blood letting than at the time of withdrawing 20％ of the blood volume in three groups (P<0. 05). Compared with HS group, the MAP and amplitudes of MEP and SSEP were significantly in-creased at 3 min after administration in E group, and the MAP was increased at 3 min after administration ( P<0. 05 or 0. 01) , and no significant change was found in amplitudes of MEP and SSEP in P group ( P>0. 05) . Conclusion Epinephrine exerts no effect on evoked potential monitoring, however, phenylephrine affects the accuracy of evoked potential monitoring in a rat model of acute hemorrhagic shock.
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Objective To determine the optimum dose of nalbuphine prepared for patient-controlled intravenous analgesia (PCIA) after caesarean section.Methods A total of 100 parturients,aged 22-40 yr,weighing 60-90 kg,of American Society of Anesthesiologists physical status Ⅰ or Ⅱ,at ≥ 37 weeks of gestation,scheduled for elective caesarean section,were divided into 4 groups (n=25 each) using a random number table:sufentanil 2.0 μ,g/kg group (group S),nalbuphine 1.5 mg/kg group (group N1),nalbuphine 2.0 mg/kggroup (group N2,) and nalbuphine2.5 mg/kggroup (group N3).In S,N1,N2 and N3 groups,sufentanil 2.0 μg/kg and nalbuphine 1.5,2.0 and 2.5 mg/kg were added to PCIA solution,respectively,tropisetron 12 mg was added,and PCIA solution was then diluted to 100 ml in normal saline.The PCA pump was set up to deliver a 1 ml bolus dose with a 10-min lockout interval and background infusion at 2 ml/h after a loading dose of 3 ml.Tramadol 50 mg was intravenously injected as a rescue analgesic to maintain visual analogue scale score at rest ≤ 4 or during activity (cough) ≤ 6.The highest Ramsay sedation score,requirement for rescue analgesics,the number of unsuccessfully delivered doses,the number of attempts and occurrence of nausea and vomiting,pruritus and somnolence within 48 h after operation were recorded.Results Compared with group S,the number of unsuccessfully delivered doses,the number of attempts and requirement for rescue analgesics were significantly decreased in N2 and N3 groups,the incidence of somnolence and the highest Ramsay sedation scores were increased in group N3 (P＜0.05),and no significant change was found in the parameters mentioned above in group N1 (P＞ 0.05).Compared with group N1,the number of unsuccessfully delivered doses,the number of attempts and requirement for rescue analgesics were significantly decreased in N2 and N3 groups,and the incidence of somnolence and the highest Ramnsay sedation scores were increased in group N3 (P＜0.05).Compared with group N2,the incidence of somnolence and the highest Ramsay sedation scores were significantly increased (P＜0.05),and no significant difference was found in the number of unsuccessfully delivered doses,the number of attempts or requirement for rescue analgesics in group N3 (P＞0.05).Conclusion The optimum dose of nalbuphine prepared for PCIA after caesarean section is 2.0 mg/kg.
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Objective To evaluate the accuracy of remifentanil target-controlled infusion (TCI) system in children.Methods Thirty ASA Ⅰ patients (aged 3-12 years and weighing 10-40 kg) scheduled for elective ear-nose-throat or urological surgery were randomly divided into two groups (n =15 each):2 ng/ml remifentanil group (group Ⅰ) and 4 ng/ml remifentanil group (group Ⅱ).Anesthesia was induced with intravenous injection of propofol 2 mg/kg and TCI of remifentanil.Remifentanil was administered with a specific TCI system incorporating the pharmacokinetic parameters of Minto.The target plasma concentration of remifentanil was set at 2 or 4 ng/ml.Tracheal intubation was facilitated with vecuronium 0.1 mg/kg after the children lost consciousness.The children were mechanically ventilated.Anesthesia was maintained with TCI of remifentanil,intravenous infusion of propofol and intermittent intravenous injection of boluses of vecuronium.The target plasma concentration of remifentanil remained unchanged and bispectraI index value was maintained at 45-65 or auditory evoked potentials index value ＜ 30 through adjusting the infusion rate of propofol.Arterial blood samples were taken at 5,10,20,30,40,50 and 60 minutes after TCI of remifentanil was started for determination of blood remifentanil concentrations by high performance liquid chromatography.Median prediction performance error (MDPE),median absolute performance error (MDAPE) and wobble of remifentanil TCI system were calculated.Results The measured concentrations of remifentanil were significantly higher than the target plasma concentrations jn both groups (P ＜ 0.05).The MDPE,MDAPE and wobble were 20.0％,30.0％ and 25.0％ respectively in group Ⅰ,and 17.5％,17.5％ and 12.5％ respectively in group Ⅱ.The MDAPE and wobble were significantly decreased in group Ⅱ compared with group Ⅰ (P ＜ 0.05).Conclusion When remifentanil is administered using a specific TCI system incorporating the pharmacokinetic parameters of Minto in children of 3-12 years old,the accuracy is not high.
ABSTRACT
Objective To evaluate the accuracy of remifentanil target-controlled infusion (TCI) system in children.Methods Thirty ASA Ⅰ patients, aged 3-12 yr, weighing 10-40 kg, scheduled for elective ear-nosethroat or urological surgery, were randomly divided into 2 groups with 15 patients in each group:2 ng/ml remifentanil group (group Ⅰ) and 4 ng/ml remifentanil group (group Ⅱ). Anesthesia was induced with iv injection of propofol 2 mg/kg and TCI of remifentanil. Remifentanil was administered with a specific TCI system incorporating the pharmacokinetic parameters of Minto.The target plasma concentrations of remifentanil were set at 2 or 4 ng/ml. Tracheal intubation was facilitated with vecuronium 0.1 mg/kg after the children lost consciousness. The children were mechanically ventilated.Anesthesia was maintained with TCI of remifentanil, iv infusion of propofol and intermittent iv boluses of vecuronium. The target plasma concentration of remifentanil remained unchanged and bispectral index value was maintained at 45-65 or auditory evoked potentials index value ＜ 30 by adusting the infusion rate of propofol.Arterial blood samples were taken at 5, 10, 20, 30, 40, 50 and 60 min after TCI remifentanil was stared for determination of blood remifentanil concentrations by high performance liquid chromatography. Median prediction performance error (MDPE),median absolute performance error (MDAPE) and wobble of remifentanil TCI system were calculated. Results The measured concentrations of remifentanil were significantly higher than the target plasma concentrations in both groups (P＜0.05). The MDPE, MDAPE and wobble were 20.0% , 30.0% and 25.0% respectively in group Ⅰ , and 17.5%, 17.5% and 12.5% respectively in group Ⅱ . TheMDAPE and wobble were significantly decreased in group Ⅱ compared with group Ⅰ(P＜0.05).Conclusion When remifentanil is administered using a specific TCI system incorporating the pharmacokinetic parameters of Minto in children of 3-12 years old, the accuracy is not high.
