OBJECTIVE To develop a high-throughput screening assay for the discovery of Omicron variant main protease(OM-Mpro) inhibitors based on the principle of fluorescence resonance energy transfer(FRET). METHODS The recombinant OM-Mpro enzyme was expressed in Escherichia coli Rosetta(DE3) cells, and further purified by a HisTrapTM chelating column. Subsequently, the enzymatic activity of OM-Mpro and wild type main protease(WT-Mpro) enzymes and inhibition of nirmatrelvir against both proteases were measured using FERT assay. With the FRET assay, OM-Mpro inhibitors were identified via high-throughput screening of an approved drug library. RESULTS The active OM-Mpro enzyme was successfully prepared from E. coli cells. OM-Mpro and WT-Mpro enzymes possessed the same enzymatic activity, and OM-Mpro remained susceptible to nirmatrelvir in vitro. Through high-throughput screening of the marketed drug library, it was found that cetylpyridinium chloride(CPC) is a mixed-type OM-Mpro inhibitor in vitro with an IC50 value of 8.76 μmol·L−1. CONCLUSION A robust FRET assay has been successfully developed based on the production of active OM-Mpro enzyme for screening of its inhibitors, and CPC is identified as a potential lead compound against OM-Mpro in vitro. This study provides a promising avenue for rapid discovery of broad-spectrum antivirals against coronavirus protease.

Objective:To evaluate the value of metagenomic Next Generation Sequencing (mNGS) for the pathogenetic diagnosis of bloodstream infections in patients with sepsis.Methods:A retrospective analysis was performed on 105 sepsis cases who received blood mNGS and blood culture tests during their hospitalization in the Intensive Care Department of the Affiliated Hospital of North Sichuan Medical College from September 2021 to August 2023, and the results were compared and analyzed. According to mNGS and blood culture results, the cases were divided into the positive group and negative group.The distribution of pathogens in the enrolled patients were analyzed, and the diagnostic performance and consistency of blood culture and mNGS were compared. The differences in clinical characteristics of patients in each group were analyzed, and the pathogenic diagnostic value of mNGS for bloodstream infections in patients with sepsis was evaluated.Results:①Among 105 blood samples, 61 cases (58.10%) had positive results of mNGS, and 32 cases (30.48%) had positive results of blood culture. The positive rate of mNGS was higher than that of blood culture, and the difference was statistically significant ( P < 0.05).The accuracy of mNGS was lower than that of blood culture②The mean values of ESR, PCT and CRP in positive group were higher than those in negative group, and the proportion of septic shock was higher than that in negative group, and the differences were statistically significant ( P < 0.05). There was no significant difference in 28-day mortality rate between the two groups ( P > 0.05). Conclusions:mNGS is beneficial to the etiological diagnosis and treatment of bloodstream infection in patients with sepsis.

Objective:To investigate the effect and mechanism of bone marrow mesenchymal stem cell (BMSC) on pyroptosis of rats with kidney injury.Methods:Bone marrow of 4-5 week-old female Sprague-Dawley (SD) rats was isolated in vitro and BMSC was obtained. The third generations of BMSC were used to further experiments. Fifteen 6 week-old SD rats were cluster-randomized divided into control group, kidney injury group and BMSC group (5 rats in each group). Rats in kidney injury group were injected with lipopolysaccharide (LPS) 1 mg/kg via tail vein; the control group was given the same amount of normal saline. BMSC group was injected with 0.5 mL BMSC (including 2×10 6 BMSC) via tail vein after modeling; the kidney injury group received the same amount of normal saline. On day 3 after these injections, serum creatinine (SCr) was detected by picric acid method, and blood urea nitrogen (BUN) was detected by diacetyl monoxime. The levels of cystatin C (Cys C), interleukins (IL-1β and IL-18) in blood were detected by enzyme-linked immunosorbent assay (ELISA). The rats were then sacrificed and their kidneys were removed for subsequent detection. The mRNA expression levels of NOD-like receptor protein 3 (NLRP3) and cysteinyl aspartate-specific protease-1 (caspase-1) of kidney were detected by quantificational real-time quantitative polymerase chain reaction (qRT-PCR). The protein expression levels of NLRP3 and caspase-1 of kidney were detected by Western blotting. Results:In vitro, after bone marrow cell suspension was cultured for 24 hours, a large number of round adherent cells and suspended cells appeared in each culture flask. After 4-5 days of culture, a large number of long spindle cells adhered to the wall, and there were still obvious impurity cells. After trypsin digestion and passage to the third generation, the long spindle adherent cells grew mainly in the culture flask and were basically purified as BMSC. In vivo, compared with the control group, the levels of SCr, BUN, Cys C, IL-1β and IL-18 in kidney injury group were increased [SCr (μmol/L): 85.22±2.29 vs. 21.80±0.59, BUN (mmol/L): 11.50±0.64 vs. 5.86±0.83, Cys C (mg/L): 0.13±0.01 vs. 0.11±0.02, IL-1β (ng/L): 31.49±1.42 vs. 4.74±0.49, IL-18 (ng/L): 29.01±1.95 vs. 1.52±0.03, all P < 0.05]. The mRNA and protein expression levels of NLRP3, caspase-1 were significantly increased [NLRP3 mRNA (2 -ΔΔCt): 3.635±0.296 vs. 1.000±0.002, caspase-1 mRNA (2 -ΔΔCt): 4.020±0.228 vs. 1.001±0.003; NLRP3 protein (NLRP3/β-actin): 1.560±0.868 vs. 0.902±0.036, caspase-1 protein (caspase-1/β-actin): 1.392±0.097 vs. 0.895±0.046, all P < 0.05]. Compared with kidney injury group, the levels of SCr, BUN, IL-1β and IL-18 in BMSC group were significantly decreased [SCr (μmol/L): 51.64±3.84 vs. 85.22±2.29, BUN (mmol/L): 9.90±0.46 vs. 11.50±0.64, IL-1β (ng/L): 24.20±1.45 vs. 31.49±1.42, IL-18 (ng/L): 12.97±1.25 vs. 29.01±1.95, all P < 0.05]. The mRNA and protein expression levels of NLRP3, caspase-1 were significantly decreased [NLRP3 mRNA (2 -ΔΔCt): 1.488±0.136 vs. 3.635±0.296, caspase-1 mRNA (2 -ΔΔCt): 1.643±0.143 vs. 4.020±0.228; NLRP3 protein (NLRP3/β-actin): 1.227±0.053 vs. 1.560±0.868, caspase-1 protein (caspase-1/β-actin): 1.159±0.107 vs. 1.392±0.097, all P < 0.05]. Conclusion:In vivo, BMSC may attenuate pyroptosis in LPS-induced kidney injury rats.

The main protease (Mpro) of SARS-CoV-2 is a highly conserved and mutation-resistant coronaviral enzyme, which plays a pivotal role in viral replication, making it an ideal target for the development of novel broad-spectrum anti-coronaviral drugs. In this study, a codon-optimized Mpro gene was cloned into pET-21a and pET-28a expression vectors. The recombinant plasmids were transformed into E. coli Rosetta(DE3) competent cells and the expression conditions were optimized. The highly expressed recombinant proteins, Mpro and Mpro-28, were purified by HisTrapTM chelating column and its proteolytic activity was determined by a fluorescence resonance energy transfer (FRET) assay. The FRET assay showed that Mpro exhibits a desirable proteolytic activity (25 000 U/mg), with Km and kcat values of 11.68 μmol/L and 0.037/s, respectively. The specific activity of Mpro is 25 times that of Mpro-28, a fusion protein carrying a polyhistidine tag at the N and C termini, indicating additional residues at the N terminus of Mpro, but not at the C terminus, are detrimental to its proteolytic activity. The preparation of active SARS-CoV-2 Mpro through codon-optimization strategy might facilitate the development of the rapid screening assays for the discovery of broad-spectrum anti-coronaviral drugs targeting Mpro.
COVID-19 ; Codon/genetics* ; Cysteine Endopeptidases/genetics* ; Escherichia coli/genetics* ; Humans ; Peptide Hydrolases ; SARS-CoV-2 ; Viral Nonstructural Proteins/genetics*

Objective:To investigate the features, diagnostic value and clinical significance of prenatal ultrasound for umbilical cord ulcer (UCU).Methods:Ultrasonographic characteristics of three fetuses with UCU diagnosed at Guangzhou Women and Children's Medical Center from January 2014 to June 2020 were reviewed. Relevant articles published from January 1, 1990, to June 1, 2020, were retrieved from Wanfang, CNKI and PubMed databases and analyzed. Likelihood ratio, adjusted Chi-square test and Fisher's exact test were used to analyze the association between the pathological results and fetal outcomes. Results:(1) Among the three fetuses with UCU, two were complicated by upper gastrointestinal obstruction and one by intrauterine infection. Two of them survived and one died after birth. Prenatal ultrasound examination of the umbilical cord and amniotic cavity showed one case was normal, while the other two showing features such as flocculent hypoechoic sign around the umbilical cord, cloudy hyperechoic sign ejecting from the umbilical cord lesion in dynamic observation, exposed umbilical vessels and ribbon-like echo around the umbilical cord. (2) No reported case of UCU had been found in any publications in China. A total of 39 reported cases of UCU complicated by duodenal or jejunal obstruction were retrieved from English literature, among which intrauterine fetal death, neonatal death and live births accounted for 30.8% (12/39), 28.2% (11/39) and 41.0% (16/39), respectively. Six cases with intrauterine abnormalities detected by prenatal ultrasound survived after emergent cesarean section, showing a positive detection rate of 15.4% (6/39), of which three obtained a snapshot of umbilical cord bleeding and three were characterized by lamellar and linear echoes around the amniotic cavity or umbilical cord. Hemorrhagic amniotic fluid was observed in 66.7% (26/39) of the fetuses and decreased heart rate occurred in 35.9%(14/39). The site, number and pathological grade of UCU were not related to the pregnancy outcomes (all P>0.05). Conclusions:Prenatal ultrasound for detecting abnormalities in umbilical cord and amniotic cavity is of a certain value in the diagnosis of UCU. Lamellar and linear echoes around the umbilical cord may be the ultrasonographic characteristics of UCU. The real-time detection of UCU bleeding by prenatal ultrasound can provide direct evidence for timely clinical treatment.

In canonical Wnt/β-catenin signaling pathway, β-catenin/TCF4 (T-cell factor 4) interaction plays an important role in the pathogenesis and development of non-small cell lung cancer (NSCLC), and it is tightly associated with the proliferation, chemoresistance, recurrence and metastasis of NSCLC. Therefore, suppressing β-catenin/TCF4 interaction in Wnt/β-catenin signaling pathway would be a new therapeutic avenue against NSCLC metastasis. In this study, considering the principle of enzyme-linked immunosorbent assay (ELISA), an optimized high-throughput screening (HTS) assay was developed for the discovery of β-catenin/TCF4 interaction antagonists. Subsequently, this ELISA-like screening assay was performed using 2 μg/mL GST-TCF4 βBD and 0.5 μg/mL β-catenin, then a high Z' factor of 0.83 was achieved. A pilot screening of a natural product library using this ELISA-like screening assay identified plumbagin as a potential β-catenin/TCF4 interaction antagonist. Plumbagin remarkably inhibited the proliferation of A549, H1299, MCF7 and SW480 cell lines. More importantly, plumbagin significantly suppressed the β-catenin-responsive transcription in TOPFlash assay. In short, this newly developed ELISA-like screening assay will be vital for the rapid screening of novel Wnt inhibitors targeting β-catenin/TCF4 interaction, and this interaction is a potential anticancer target of plumbagin in vitro.
Carcinoma, Non-Small-Cell Lung ; Cell Line, Tumor ; Enzyme-Linked Immunosorbent Assay ; High-Throughput Screening Assays ; Humans ; Lung Neoplasms ; Transcription Factor 4/genetics* ; beta Catenin/genetics*

Objective:To study the real-world outcome of China FDA-approved Sofosbuvir (SOF)/Velpatasvir (VEL) in Northwest China.Methods:In this multicenter, prospective, real-world cohort study, we recruited patients from 10 sites from Northwest China, who were chronically infected with HCV GTs 1-6 from 06/2018 to 09/2019. Patients received SOF (400mg)/VEL (100mg) for 12 weeks, and with ribavirin 900-1200 mg for GT3 cirrhosis and for any genotype decompensated cirrhosis. The primary endpoint was sustained virological response at 12-weeks post-treatment (SVR12) and safety. The secondary endpoint was the change of liver function after the achievement of SVR12.Results:Totally, 143 patients were enrolled in the study, four patients were lost to follow-up and one died during the follow-up, 138 patients were included in per-protocol analysis. Of the 138 patients, the mean age 53 years, 53.6% male, 94.2% Han nationality, 53.6% liver cirrhosis, 10.1% HBsAg +, 6.5% renal dysfunction, 5.1% treatment-experienced, and 16.7% patients received ribavirin treatment. The genotype distribution was as follows: 35.5% GT1, 42.8% GT2, 15.9% GT3, and 5.8% un-typed. The SVR12 rate was 96.5% (138/143, 95% CI: 93.5%-99.6%) for intention-to-treat analysis, and in per-protocol analysis, all 138 patients obtained SVR12 (100%). Compared with baseline, the serum total bilirubin, ALT and AFP levels decreased (all P < 0.05), as well as increased ALB and platelet count (all P < 0.001) at post-treatment 12-weeks. Overall adverse events (AEs) rate is 29.0%, and the most common AEs were anemia (14.5%) and fatigue (8.0%). Severe side effects (edema and fatigue) occurred in 2 patients, one of whom needed a short-term interruption of treatment due to fatigue. Conclusion:In this real-world cohort study, 12-week SOF/VEL regimen with or without ribavirin achieved high SVR12 rates (96.5%-100% overall) with excellent safety profile among patients with HCV GT1/2/3 infection including patients with GT3 and cirrhosis, and led to improvement of liver function.

Polo-like kinase 1 (Plk1) is widely regarded as one of the most promising targets for cancer therapy due to its essential role in cell division and tumor cell survival. At present, most Plk1 inhibitors have been developed based on kinase domain, some of which are in clinical trial. However, inhibitors targeting kinase domain face off-target effect and drug resistance owing to the conserved nature and the frequent mutations in the ATP-binding pocket. In addition to a highly conserved kinase domain, Plk1 also contains a unique Polo-Box domain (PBD), which is essential for Plk1's subcellular localization and mitotic functions. Inhibitors targeting Plk1 PBD show stronger selectivity and less drug resistance for cancer therapy. Therefore, Plk1 PBD is an attractive target for the development of anti-cancer agents. In this review, we will summarize the up-to date drug discovery for targeting Plk1 PBD, including the molecular structure and cellular functions of Plk1 PBD. Small-molecule inhibitors targeting Plk1 PBD not only provide an opportunity to specifically inhibit Plk1 activity for cancer treatment, but also unveil novel biological basis regarding the molecular recognition of Plk1 and its substrates.
Cell Cycle Proteins/genetics* ; Neoplasms/drug therapy* ; Protein Kinase Inhibitors/pharmacology* ; Protein-Serine-Threonine Kinases/genetics* ; Proto-Oncogene Proteins/genetics*

To prepare polyclonal antibody (PcAb) against Escherichia coli filamentous thermosensitive protein Z (Ec-FtsZ), the artificially synthesized gene fragment coding Ec-FtsZ was subcloned into pET-22b(+) plasmid, and Ec-FtsZ protein was expressed in E. coli BL21(DE3) cell under an optimal bacterial expression condition. Then Ec-FtsZ protein was purified by HisTrap affinity chromatography, and the GTPase (Guanosine triphosphatase) activity of purified Ec-FtsZ protein was further analyzed by malachite green assay. Subsequently, the purified Ec-FtsZ protein was used to immunize rat subcutaneously for preparation of anti-Ec-FtsZ PcAb. The results of enzyme-linked immunosorbent assay (ELISA), Western blotting analysis and immunofluorescence assay showed that the titer of PcAb was 1:256 000, and PcAb exhibited a perfect antigenic specificity against purified and endogenous Ec-FtsZ protein. All these data indicated that the anti-Ec-FtsZ PcAb is successfully prepared, which can be used for further cellular function study and biochemical analysis of Ec-FtsZ protein in vivo.
Animals ; Antibodies ; Antibody Specificity ; Bacterial Proteins ; Blotting, Western ; Cytoskeletal Proteins ; Enzyme-Linked Immunosorbent Assay ; Escherichia coli ; Plasmids ; Rats

To develop an enzyme-linked immunosorbent assay (ELISA)-based high throughput screening (HTS) method for β-catenin/Lef1 interaction antagonists screening, Escherichia coli Rosetta (DE3) competent cells were transformed with β-catenin-pET-30a(+) plasmid. β-catenin protein was expressed after induction and purified using affinity chromatography. The biological activity of purified β-catenin was further analyzed by GST Pulldown assay. The β-catenin/GST-Lef1 binding model was established using ELISA principle, and the ELISA-based HTS method was further optimized through determination of an optimal coated concentration of GST-Lef1 and working concentration of β-catenin. The results showed that β-catenin protein was successfully expressed and purified. The GST Pulldown assay demonstrated a perfect biological activity for purified β-catenin. Subsequently, the ELISA-based HTS method was performed using 10 μg/mL GST-Lef1 and 6 μg/mL β-catenin, with the Z factor of 0.76. Taken together, we have successfully developed a simple, robust and reliable ELISA-based HTS method for screening of novel Wnt inhibitors targeting β-catenin/Lef1 interaction.
Antineoplastic Agents ; Enzyme-Linked Immunosorbent Assay ; High-Throughput Screening Assays ; Lymphoid Enhancer-Binding Factor 1 ; beta Catenin