ObjectiveThis study employs a special conformational engineering (CE) technology to construct an α-chymotrypsin-like active center, which includes a catalytic triad, an oxyanion hole, and a substrate-binding site, on silver nanoparticles (AgNPs), thereby creating an AgNP-based artificial hydrolase with high catalytic activity. This study provides a new approach for the design of highly efficient artificial enzymes and enzyme-mimicking. MethodsAgNPs were chosen as the scaffold to build the an α-chymotrypsin-like active center. A special CE procedure enables the designed peptide, Triad5, to adopt an α‑helical conformation on AgNPs, with the key catalytic residues located on one side of the α-helix forming a catalytic active center with a catalytic triad, an oxyanion hole, and a substrate-binding site. The CE procedure consists of three steps, including conformation induction via trifluoroethanol (TFE), conformation stabilization on AgNPs via Ag-S bonds, and TFE removal via lyophilization. Circular dichroism (CD) spectra were used to confirm the formation and stabilization of the α-helix conformation. Mutations of the key residues combined with stopped-flow kinetic experiments were used to demonstrate the indispensability of each key residue and the synergistic effects among the catalytic triad, the oxyanion hole, and the substrate-binding site. ResultsCD spectra show that the designed Triad5 alone is in random coil conformation; when conjugated on AgNPs, Triad5 still remains largely unstructured; but after the CE treatment, Triad5 adopts a typical α-helical conformation on AgNPs as designed, thus produces an AgNP-based artificial hydrolase, Silverzyme. Silverzyme exhibits extremely high hydrolytic activity towards p-nitrophenyl acetate (p-NPA), with an extremely high catalytic turnover number per active site of 3.5 s^-1, which is even higher than that of α-chymotrypsin. As a comparison, the AgNP-Triad5 conjugate without CE treatment shows much lower catalytic activity than Silverzyme, highlighting the important role of the right conformation of the active center for the catalytic activity and the power of the CE treatment. When the key residues of the catalytic triad of Silverzyme were mutated to alanine, the overall catalytic efficiency of this mutant dropped by about 2 orders of magnitude, unambiguously demonstrating the key role of the designed catalytic triad. Similarly, when the residues for the oxyanion hole were deleted, the mutant with the intact catalytic triad also showed significantly decreased catalytic activity, highlighting the indispensable role of the oxyanion hole for the catalytic activity. Unexpectedly, when both the catalytic triad and the oxyanion hole were kept intact, a slight change of the binding site also resulted in significantly decreased catalytic activity, indicating that the designed binding site is at the right position to align the substrate in the right orientation in the active center for catalytic hydrolysis. These results confirm the synergy among the catalytic triad, the oxyanion hole, and the substrate-binding site, indicating successful mimicking of the active center of α-chymotrypsin. Moreover, Silverzyme shows better thermal stability than α-chymotrypsin, and can even hydrolyze the tough non-activated ester diethyl phthalate, a priority pollutant by the United States Environmental Protection Agency (USEPA). ConclusionThis study successfully mimicked the complex catalytic active center of α-chymotrypsin using a conformational engineering strategy, and produced a highly active artificial hydrolase with a well-defined structure and catalytic mechanism. The findings highlight the significant potential of conformational engineering.

Objective:Previous studies have shown that insomnia is closely related to erectile dysfunction(ED).However,the causal relationship between them is still unclear.Mendelian randomization(MR)provides a new method for studying the relationship between the two,and the theory of heart-kidney interaction in TCM provides a new idea for exploring the causal relationship between them.Methods:Based on the statistical data collected by genome-wide association studies(GWAS),the causal relationship be-tween insomnia and ED was discussed by MR.Inverse variance weighted(IVW)is the main analysis method,and weighted median(WME),simple mode(SM),weighted mode(WM)and MR Egger method were the supplementary analysis to evaluate the causal effect.MR-Egger intercept test,Cochran Q test and leave-one-out method were used in sensitivity analysis to verify the reliability of MR results.Results:Thirty-nine SNPs significantly related to insomnia were finally included for MR analysis.The results of IVW method in MR analysis showed that insomnia had a significant causal relationship with the increased risk of ED(OR=3.111,95％CI=1.566-6.181,P=1.193 × 10-3).The results obtained by MR-Egger method,WME method,WM method and SM method were consistent with IVW method in the direction of effect.The sensitivity results suggested that the results of this study were robust.Conclusion:Our study reveals the causal relationship between insomnia and ED,which provides a new basis for future clinical practice and prevention and treatment of ED.

Objective To explore the brain damage of SD rats under different time points of hypobaric hypoxia exposure.Methods A rat high-altitube cerebral edema(HACE)model was constructed by simulating an altitude of 6 000 m in a hypobaric hypoxia animal experimental chamber.Thirty-six SD male rats were randomly divided into the control group and the hypobaric hypoxia exposure 3,7 and 14 d groups,with 9 rats in each group.Except for the control group,the rats in each group were continuously exposed to hypobaric hypoxia for 3,7,and 14 d.At the end of the modeling period,serum was collected by blood sampling via the abdominal aorta,and brain tissue samples were taken.The wet-to-dry ratio(W/D)of brain tissue was calculated,and the levels of relevant oxidative enzymes in serum and brain tissue were measured.The expression levels of hypoxia-inducible factor-1α(HIF-1α)and aquaporin 4(AQP4)mRNAs in brain tissue were detected by real-time fluorescence quantitative polymerase chain reaction.Results The W/D of brain tissues in the control group and the group exposed to hypobaric hypoxia for 3,7 and 14 d were 4.46±0.12,4.98±0.16,5.07±0.18 and 4.95±0.07;the superoxide dismutase contents were(111.86±2.45),(90.73±1.48),(79.64±2.56)and(55.33±1.45)U·g-1;the glutathione contents were(126.91±5.18),(125.26±1.53),(56.20±2.17)and(122.73±1.78)μg·mL-1;the malondialdehyde contents were(230.94±2.00),(362.65±3.28),(407.34±3.47)and(237.50±1.59)nmol·g-1;the relative expression levels of HIF-1 α mRNA were 1.00±0,2.99±0.49,4.72±0.49 and 1.91±0.28;the relative expression levels of AQP4 mRNA were 1.00±0,2.62±0.34,8.38±0.84 and 5.27±0.42,respectively.Statistically significant differences were found between the above indexes in the 3,7 and 14 d of hypobaric hypoxia exposure group compared with the control group(P＜0.05,P＜0.01).Conclusion Different time of hypobaric hypoxia exposure can up-regulate the expression of AQPs proteins in HACE rats and cause the disruption of the blood-brain barrier,and the HACE model constructed in the hypobaric hypoxia chamber with 6 000 m intervention for 7 d was more stable.

Objective:To investigate the mechanisms of baicalin in treating septic acute liver injury through a combination of network pharmacology and animal experiments.Methods:Thirty male C57BL/6 mice (6 weeks old) were divided into five groups ( n=6): control group (normal saline), model group [lipopolysaccharide (LPS) 10 mg/kg, intraperitoneal injection], low-dose baicalin group (10 mg/kg), high-dose baicalin group (20 mg/kg), and baicalin-only group (20 mg/kg, without LPS). Baicalin was administered orally for 14 consecutive days prior to modeling. Mice were sacrificed 24 h after LPS injection. Alanine transaminase, aspartate transaminase liver tissue histopathology were measured; neutrophil infiltration was visualized using immunofluorescence; mRNA expression levels of interleukin (IL)-1β, IL-17, IL-6, and tumor necrosis factor (TNF)-α were detected by RT-qPCR; and the expression of Toll-like receptor 4 (TLR4) and phosphorylated nuclear factor (NF)-κB proteins were analyzed by Western blotting. Results:In the LPS model group, the ALT, AST, and histopathological injury score were (148.60±22.02) U/L, (81.58±11.59) U/L, and 8.50(7.75, 9.25), respectively. These indicators were significantly reduced in the high-dose baicalin group with (77.90±16.79) U/L, (49.92±14.89) U/L, and 1.00(1.00, 2.25) (all P<0.05). Compared with the LPS group, neutrophil infiltration in the liver of high-dose baicalin group was also significantly reduced [1.18%(0.98%, 1.22%) vs. 6.13%(5.41%, 8.69%), P<0.05]. RT-qPCR results showed that the relative mRNA expression levels of inflammatory cytokines IL-1β [(1.03±0.06) vs. (2.60±0.34)], IL-17 [(1.21±0.12) vs. (2.94 ± 0.39)], IL-6 [(1.37±0.26) vs. (2.73±0.18)], and TNF-α [(1.18±0.10) vs. (3.30±0.92)] were significantly decreased in the high-dose baicalin group compared with the LPS group (all P<0.05). Western blot analysis revealed that the relative protein expression levels of TLR4 [(1.25±0.13) vs. (1.73±0.06)] and phosphorylated NF-κB [(1.25±0.25) vs. (1.79±0.12)] were also significantly lower in the high-dose baicalin group (both P<0.05). Conclusion:Baicalin reduces liver injury in septic mice by downregula-ting the expression of pro-inflammatory cytokines IL-1β, IL-6, TNF-α, and IL-17, potentially through the inhibition of the TLR4/NF-κB signaling pathway.

The molecular mechanisms underlying the develop-ment and metastasis of prostate cancer remain elusive.This comprehensive review delves into the intricate role of cofilin,an actin-binding protein,in the pathogenesis and progression of prostate cancer.Cofilin is a significant protein in cytoskeletal dynamics,and any dysregulation may result in the morphological changes in normal cells and the invasion and metastasis of tumor cells.Research has revealed that the activity of cofilin is regula-ted by various mechanisms,including phosphorylation/dephos-phorylation and interactions with other molecules.Moreover,this review discusses promising therapeutic interventions,such as co-filin inhibitors and gene therapy,which have demonstrated effica-cy in preclinical models.The challenge of clinically preventing the transition to castration-resistant prostate cancer and tumor metastasis is widely recognized,necessitating the development of precise drug treatments and biomarker identification.As a key regulatory protein,cofilin provides a more comprehensive refer-ence for the prevention and treatment of prostate diseases.

Objective To observe the application effect of bedside contrast-enhanced ultrasound combined with gas-water alternating injection method in severe patients with nasointestinal catheterization.Methods A total of 150 severe patients who were admitted to intensive care unit(ICU)and emergency intensive care unit(EICU)and required nasointestinal catheterization were collected.Patients were separated into the blind insertion method group(catheterization without other auxiliary equipment,n=50),the ultrasound method group(ultrasound-guided catheterization,n=53),and the combined method group(bedside contrast-enhanced ultrasound combined with gas-water alternating injection method,n=47)according to the wishes of patients or their families.The catheterization success rate,feeding standard-reaching rate within one week,catheterization time and incidence of adverse events were compared between three groups.Kappa test was used to compare the consistency of three methods with X-ray examination results after catheterization.Receiver operating characteristic(ROC)curve was used to evaluate the catheterization effect.Results The catheterization success rate and the feeding standard-reaching rate within one week were increased successively in the blind insertion method group,the ultrasound method group and the combined method group,and the catheterization time shortened in turn(P＜0.05).The consistency of blind insertion method,ultrasound method,combined method with X-ray examination was strong(Kappa=0.730),very strong(Kappa=0.835)and very strong(Kappa=0.911),respectively.Results of ROC curve showed that the areas under the ROC curve of the blind insertion method group,the ultrasound method group and the combined method group increased in turn,which were 0.838(95%CI:0.661-1.000),0.918(95%CI:0.763-1.000)and 0.988(95%CI:0.959-1.000),and the combined method group had the best catheterization effect.There were no significant differences in the incidence of adverse events such as hiccup,abdominal distension,diarrhea,aspiration and gastrointestinal bleeding between the three groups(P>0.05).Conclusion Bedside contrast-enhanced ultrasound combined with gas-water alternating injection method can improve the success rate of nasointestinal catheterization in severe patients,shorten the catheterization time and without increasing the incidence of adverse events.

Objective To explore the brain damage of SD rats under different time points of hypobaric hypoxia exposure.Methods A rat high-altitube cerebral edema(HACE)model was constructed by simulating an altitude of 6 000 m in a hypobaric hypoxia animal experimental chamber.Thirty-six SD male rats were randomly divided into the control group and the hypobaric hypoxia exposure 3,7 and 14 d groups,with 9 rats in each group.Except for the control group,the rats in each group were continuously exposed to hypobaric hypoxia for 3,7,and 14 d.At the end of the modeling period,serum was collected by blood sampling via the abdominal aorta,and brain tissue samples were taken.The wet-to-dry ratio(W/D)of brain tissue was calculated,and the levels of relevant oxidative enzymes in serum and brain tissue were measured.The expression levels of hypoxia-inducible factor-1α(HIF-1α)and aquaporin 4(AQP4)mRNAs in brain tissue were detected by real-time fluorescence quantitative polymerase chain reaction.Results The W/D of brain tissues in the control group and the group exposed to hypobaric hypoxia for 3,7 and 14 d were 4.46±0.12,4.98±0.16,5.07±0.18 and 4.95±0.07;the superoxide dismutase contents were(111.86±2.45),(90.73±1.48),(79.64±2.56)and(55.33±1.45)U·g-1;the glutathione contents were(126.91±5.18),(125.26±1.53),(56.20±2.17)and(122.73±1.78)μg·mL-1;the malondialdehyde contents were(230.94±2.00),(362.65±3.28),(407.34±3.47)and(237.50±1.59)nmol·g-1;the relative expression levels of HIF-1 α mRNA were 1.00±0,2.99±0.49,4.72±0.49 and 1.91±0.28;the relative expression levels of AQP4 mRNA were 1.00±0,2.62±0.34,8.38±0.84 and 5.27±0.42,respectively.Statistically significant differences were found between the above indexes in the 3,7 and 14 d of hypobaric hypoxia exposure group compared with the control group(P＜0.05,P＜0.01).Conclusion Different time of hypobaric hypoxia exposure can up-regulate the expression of AQPs proteins in HACE rats and cause the disruption of the blood-brain barrier,and the HACE model constructed in the hypobaric hypoxia chamber with 6 000 m intervention for 7 d was more stable.

Background and Aims:Papillary thyroid carcinoma(PTC),the most common type of thyroid cancer,has been rapidly increasing in incidence worldwide,posing a serious threat to individual health and public healthcare systems.Exposure to low-to-moderate doses of ionizing radiation is more relevant to the daily lives of the general population and,therefore,raises greater public health concerns.It has also been widely recognized as a potential factor in immune system remodeling.This study was conducted to investigate the impact of low-to-moderate dose ionizing radiation on the tumor immune microenvironment of PTC,aiming to reveal the potential hazards of such radiation exposure in PTC patients.Methods:Two datasets(GSE29265 and GSE35570)containing RNA-seq data and corresponding clinical information were retrieved and downloaded from the GEO database.These datasets included thyroid cancer samples from patients exposed to ionizing radiation due to the Chernobyl disaster,as well as sporadic thyroid cancer cases.After data cleaning,merging,batch effect correction,differential gene expression analysis,functional enrichment analysis,immune cell infiltration analysis,and tumor microenvironment analysis were performed using R language.Results:In tumor samples,the radiation-exposed group exhibited significant differential gene expression compared to the sporadic group,with three genes upregulated and 27 genes downregulated.These differentially expressed genes were primarily enriched in biological functions closely related to immune responses,including chemokine activity,immune cell chemotaxis,and tumor immunity.Immune cell infiltration analysis indicated that radiation exposure had a limited impact on immune cell infiltration in normal samples.However,in tumor samples,the immune and ESTIMATE scores were significantly lower in the radiation-exposed group than in the sporadic group.Further analysis revealed that total T cells,CD4+T cells,CD8+T cells,B cells,and cytotoxic lymphocytes exhibited significantly lower infiltration levels in the tumor microenvironment of the radiation-exposed group than the sporadic group.Conclusion:Although low-to-moderate dose ionizing radiation has a relatively minor impact on normal thyroid tissue,it significantly reduces the infiltration of various immune cell subtypes in the PTC tumor microenvironment.This reduction in immune infiltration may have important implications for disease progression.

The purpose of this study is to develop a shark single domain antibody(SdAb)targeting a unique B cell epitope in the SARS-CoV-2 spike protein,and explore its role in the immunological detection targeting SARS-CoV-2 spike protein S.A u-nique peptide S9 was artificially synthesized based on the sequence of a unique B cell epitope of SARS-CoV-2 spike protein,then it was conjugated to the carrier protein KLH.It was used as an immunogen for subcutaneous injection into shark back and boosted according to the standard immunization protocol.Blood collected from shark tail vein and peripheral blood lymphocytes(PBL)were isolated.Total RNA was purified from PBL and transcribed to cDNA by reverse transcription.Shark vNAR frag-ments were amplified from cDNA templates and cloned into pComb3XSS vector to obtain phage library.A positive clone named T01 was obtained through screening the phage library by indirect ELISA.Then its gene was cloned into the expression vector pET-28a.The SdAb T01 was then prokaryotically expressed and purified,and its specific recognition of the SARS-CoV-2 spike protein S was indentified by Western-blot(WB),indirect ELISA and IF A.T01 binds well with peptide S9 at EC50 value of 2.050±0.064 nmol/L.The purified SdAb T01 was proven by WB to be able to selectively detect recombinant spike protein sub-unit 1(S1)of SARS-CoV-2,with no cross-reactive to recombinant spike protein subunit 1 of other six human coronavirus.It was showed by ELISA that SdAb T01 can sensitively detect the recombinant N terminal domain(NTD)of SARS-CoV-2 pro-tein.Moreover,it also specifically recognizes the spike protein of SARS-CoV-2 that was transiently expressed in transfected HEK293 cells by IFA.Therefore,a shark single domain antibody targeting a unique B cell epitope in the spike protein of SARS-CoV-2 was successfully developed,and has shown potential immunodiagnostic value by WB,ELISA and IFA.Thus,it provides an effective tool for unique antigen detection of SARS-CoV-2.

Objective To observe the application effect of bedside contrast-enhanced ultrasound combined with gas-water alternating injection method in severe patients with nasointestinal catheterization.Methods A total of 150 severe patients who were admitted to intensive care unit(ICU)and emergency intensive care unit(EICU)and required nasointestinal catheterization were collected.Patients were separated into the blind insertion method group(catheterization without other auxiliary equipment,n=50),the ultrasound method group(ultrasound-guided catheterization,n=53),and the combined method group(bedside contrast-enhanced ultrasound combined with gas-water alternating injection method,n=47)according to the wishes of patients or their families.The catheterization success rate,feeding standard-reaching rate within one week,catheterization time and incidence of adverse events were compared between three groups.Kappa test was used to compare the consistency of three methods with X-ray examination results after catheterization.Receiver operating characteristic(ROC)curve was used to evaluate the catheterization effect.Results The catheterization success rate and the feeding standard-reaching rate within one week were increased successively in the blind insertion method group,the ultrasound method group and the combined method group,and the catheterization time shortened in turn(P＜0.05).The consistency of blind insertion method,ultrasound method,combined method with X-ray examination was strong(Kappa=0.730),very strong(Kappa=0.835)and very strong(Kappa=0.911),respectively.Results of ROC curve showed that the areas under the ROC curve of the blind insertion method group,the ultrasound method group and the combined method group increased in turn,which were 0.838(95%CI:0.661-1.000),0.918(95%CI:0.763-1.000)and 0.988(95%CI:0.959-1.000),and the combined method group had the best catheterization effect.There were no significant differences in the incidence of adverse events such as hiccup,abdominal distension,diarrhea,aspiration and gastrointestinal bleeding between the three groups(P>0.05).Conclusion Bedside contrast-enhanced ultrasound combined with gas-water alternating injection method can improve the success rate of nasointestinal catheterization in severe patients,shorten the catheterization time and without increasing the incidence of adverse events.