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.

Aim To investigate the regulatory mecha-nisms of donepezil on the expression and enzymatic ac-tivity of cytochrome P450 3A4(CYP3A4),elucidate the synergistic impact of hypoxia on CYP3A4 function,and reveal its potential association with drug-induced cardiotoxicity,particularly QT interval prolongation.Methods Western blot,co-immunoprecipitation,and gene knockdown techniques were employed to evaluate the effects of donepezil and hypoxia on CYP3A4 pro-tein expression.CYP3A4 enzymatic activity was as-sessed using an in vitro incubation system with rat liver microsomes combined with high-performance liquid chromatography(HPLC),and the half-maximal inhib-itory concentration(IC50)was determined.Results Donepezil(10 μmol·L-1)and hypoxia reduced CYP3A4 protein expression to 31.75％and 45.90％of the control levels,respectively.Both interventions activated the gp78-mediated ubiquitin-proteasome path-way,significantly increasing CYP3A4 ubiquitination levels by 2.1-fold compared to the control group,thereby promoting proteasomal degradation.Donepezil inhibited CYP3A4 enzyme activity with an IC50 of 83.4μmol·L-1,and hypoxia synergistically enhanced this inhibitory effect,reducing the IC50 to 20.79 μmol·L-1.Conclusion Donepezil downregulates CYP3A4 function through dual mechanisms involving ubiquitin-mediated proteasomal degradation and direct enzymatic inhibition.Hypoxia potentiates this effect,leading to impaired metabolism of CYP3A4 substrate drugs,ele-vated plasma drug concentrations(1.6-2.3-fold in-crease compared to normal metabolic conditions),and an increased risk of QT interval prolongation and other forms of cardiotoxicity.

Aim To investigate the effect of Shenqi Dihuang decoction(SQDH)on henoch-schonlein pur-pura nephritis(HSPN)rats by regulating AMPK/Sirt1/Nrf2 mediated ferroptosis and the possible mech-anism.Methods Thirty SD rats were randomly divid-ed into a control group(Control),HSPN group,SQDH low-dose group(SQDH-L,5.4 g·kg-1),SQDH high-dose group(SQDH-H,21.6 g·kg-1),and SQDH high-dose+AMPK inhibitor group(SQDH-H+CC,20 mg·kg-1),with six rats in each group.Except for the control group,all other groups of rats were injected intraperitoneally with ovalbumin and complete Freund's adjuvant to establish HSPN rat models.After the successful construction of the model,each group of rats was orally administered with the cor-responding dosage or physiological saline once a day for five weeks.HE staining was used to observe the his-topathological changes in renal tissues;immunohisto-chemistry(IHC)was employed to detect the deposition of IgA and IgG in renal tissues;serum biochemical pa-rameters of renal function and urinary protein levels were measured;commercial assay kits were utilized to determine oxidative stress markers and Fe2+levels in renal tissues;Western blot analysis was performed to assess ferroptosis-related proteins and the protein ex-pression of the AMPK/Sirt1/Nrf2 signaling pathway in renal tissues.Results Compared with the control group,the HSPN group showed significant pathological damage in kidney tissue,with significantly increased scores,increased deposition of IgA and IgG in kidney tissue,decreased serum total protein(TP)and albu-min(ALB),and average increases in serum creatinine(Cre),urea nitrogen(BUN),and urinary protein levels(P＜0.05).The levels of MDA,ROS,Fe2+,and ACSL4 protein expression in the kidney tissue sig-nificantly increased,while SOD activity,SLC7A11,GPX4,p-AMPK/AMPK,Sirt1,and Nrf2 protein ex-pression significantly decreased(P＜0.05).Com-pared with the HSPN group,the pathological damage to renal tissue was reduced,IgA and IgG deposition in renal tissue decreased,TP and ALB decreased,Cre,BUN,and urinary protein levels were all reduced(P＜0.05),and the levels of MDA,ROS,Fe2+,and ACSL4 protein expression in renal tissue were signifi-cantly reduced in each dose group of SQDH rats.SOD activity,SLC7A11,GPX4,p-AMPK/AMPK,Sirt1,and Nrf2 protein expression significantly increased(P＜0.05).Compared with the SQDH-H group,the AMPK inhibitor CC could inhibit the AMPK/Sirt1/Nrf2 signaling pathway induced ferroptosis and reverse the protective effect of SQDH on renal injury in HSPN rats.Conclusions SQDH can improve renal injury in HSPN rats,and its mechanism may be related to the activation of AMPK/Sirt1/Nrf2 signaling pathway to in-hibit ferroptosis.

Objective To improve and refine the relevant regulations and guiding principles of warnings on drug instructions and labels in China.Methods This paper sorted out the drug instructions of small molecule anti-tumor drugs listed by the U.S.Food and Drug Administration(FDA)from 2005 to 2022,included the drugs mentioned in the QT interval prolongation risk,analyzed the clinical research and QT research results,and sorted out the identification and warning rules of the instructions.Results A total of 35 drugs were included,4 drugs wrote the risk of QT interval prolongation in the black box warning,21 drugs were wrote in the warning and precautions position,6 drugs were wrote in the adverse reaction section,and 2 drugs were only described under clinical pharmacology section.According to the severity of the QT interval prolongation caused by the drug and whether there were serious clinical consequences,they were displayed in the warnings(black box warnings),precautions(warnings and precautions)and adverse reactions in the instructions.Conclusion The aim of this article is to provide a reference for the writing of QT risk warning information of the instructions of domestic drug production enterprises and regulatory departments.It is recommended to clarify the severity of drug safety and the location of the instructions in clinical research,and continue to carry out safety monitoring and update the instructions in time after listing.

Objective:To investigate the predictive value of color Doppler ultrasound combined with electrocardio-gram for right heart dys function in patients with pulmonary heart disease(PHD).Methods:A total of 100 PHD patients admitted in Dongcheng Branch of First Affiliated Hospital of Anhui Medical University between January 2020 and December 2023 were retrospectively analyzed.According to results of 6min walking test(6MWT),pa-tients were divided into good right heart function group(n=64,≥350m)and right heart dysfunction group(n=36,＜350m).The indexes of cardiac color ultrasound[isovolumic relaxation time(IVRT),isovolumetric contraction time(IVCT)and right ventricular Tei index],ECG[24h mean R-R interval standard deviation(SDNN),normal R-R interval standard deviation per 5min(SDANN)and the ratio of low frequency components to high frequency components(LF/HF)]were compared between two groups.Receiver operating characteristic(ROC)curve was drawn to analyze the diagnostic value of color Doppler ultrasound,ECG and their combination for right heart dys-function in PHD patients.Spearman correlation coefficient was used to analyze the association of color Doppler ul-trasound,ECG and their combination with right heart dysfunction in PHD patients.Results:Compared with those in good right heart function group,patients in right heart dysfunction group had significant higher IVRT[(120.64±14.08)ms vs.(97.87±10.93)ms],IVCT[(84.28±12.33)ms vs.(71.92±10.61)ms]and Tei index[(0.85±0.11)vs.(0.63±0.07)](P＜0.001 all),and significant lower SDNN[(75.52±12.58)ms vs.(85.58±11.75)ms],SDANN[(63.86±10.92)ms vs.(76.75±11.71)ms]and LF/HF[(1.33±0.19)vs.(1.84±0.27)](P＜0.001 all).ROC curve indicated that the AUC of color Doppler ultrasound combined ECG in diagnosing right heart dysfunction in PHD patients was 0.911(95％CI 0.838～0.959),which was significantly higher than those of color Doppler ultrasound[0.775(95％CI 0.681～0.853),Z=2.404,P=0.016]and ECG[0.688(95％CI 0.588～0.777),Z=3.968,P=0.001]alone.Spearman correlation analysis indicated that there was a significant positive correlation of color Doppler ultrasound(r=0.547),ECG(r=0.375)and their combination(r=0.810)with right heart dysfunction in PHD patients(P＜0.001 all),and the correlation between combined detection and right heart dysfunction in PHD patients was significantly higher.Conclusion:Color Doppler ultrasound combined with ECG possesses high diagnostic performance for right heart dysfunction in PHD patients.

Aim To investigate the protective effect of Shengmai Yin on myocardial ischemia/reperfusion in-jury(MI/RI)in vitro and in vivo and to unravel the underlying mechanism.Methods SD rats were divid-ed into the sham group,model group,and Shengmai Yin group(SM).Rat MI/RI model was established.Cardiac function,infarct area,pathological changes,cardiomyocyte apoptosis,macrophage infiltration,and serum cTnT and CK-MB levels were measured.The mRNA and protein expressions of Calpain-1 and Cal-pain-2 were assessed.The hypoxia/reoxygenation(H/R)model was constructed in H9c2 cells.The active ingredients of Shengmai Yin were screened using net-work pharmacology and verified by CCK-8.In the car-diomyocytes H/R model,Fluo-4 AM staining was used to detect the changes of Ca2+levels.Results Com-pared with model group,LVEF and LVFS of Shengmai Yin-treated rats increased,myocardial infarction area was reduced,while myocardial tissue injury was allevi-ated.Myocardial apoptosis rate and the number of macrophages were reduced.Similarly,cTnT and CK-MB levels decreased.In addition,the expression lev-els of Calpain-1 and Calpain-2 mRNA and protein de-creased in the SM treatment group.Under the H/R model,all the active ingredients of Shengmai decoction had protective effects on cardiomyocytes,and the treat-ment could reduce the level of Ca2+in cardiomyocytes.Conclusions Shengmai Yin has protective effects on MI/RI in rats.This effect may be related to the de-crease in Ca2+levels,as well as Calpain-1 and Calap-in-2 mRNA and protein expression.

Objective To improve and refine the relevant regulations and guiding principles of warnings on drug instructions and labels in China.Methods This paper sorted out the drug instructions of small molecule anti-tumor drugs listed by the U.S.Food and Drug Administration(FDA)from 2005 to 2022,included the drugs mentioned in the QT interval prolongation risk,analyzed the clinical research and QT research results,and sorted out the identification and warning rules of the instructions.Results A total of 35 drugs were included,4 drugs wrote the risk of QT interval prolongation in the black box warning,21 drugs were wrote in the warning and precautions position,6 drugs were wrote in the adverse reaction section,and 2 drugs were only described under clinical pharmacology section.According to the severity of the QT interval prolongation caused by the drug and whether there were serious clinical consequences,they were displayed in the warnings(black box warnings),precautions(warnings and precautions)and adverse reactions in the instructions.Conclusion The aim of this article is to provide a reference for the writing of QT risk warning information of the instructions of domestic drug production enterprises and regulatory departments.It is recommended to clarify the severity of drug safety and the location of the instructions in clinical research,and continue to carry out safety monitoring and update the instructions in time after listing.

Aim To investigate the regulatory mecha-nisms of donepezil on the expression and enzymatic ac-tivity of cytochrome P450 3A4(CYP3A4),elucidate the synergistic impact of hypoxia on CYP3A4 function,and reveal its potential association with drug-induced cardiotoxicity,particularly QT interval prolongation.Methods Western blot,co-immunoprecipitation,and gene knockdown techniques were employed to evaluate the effects of donepezil and hypoxia on CYP3A4 pro-tein expression.CYP3A4 enzymatic activity was as-sessed using an in vitro incubation system with rat liver microsomes combined with high-performance liquid chromatography(HPLC),and the half-maximal inhib-itory concentration(IC50)was determined.Results Donepezil(10 μmol·L-1)and hypoxia reduced CYP3A4 protein expression to 31.75％and 45.90％of the control levels,respectively.Both interventions activated the gp78-mediated ubiquitin-proteasome path-way,significantly increasing CYP3A4 ubiquitination levels by 2.1-fold compared to the control group,thereby promoting proteasomal degradation.Donepezil inhibited CYP3A4 enzyme activity with an IC50 of 83.4μmol·L-1,and hypoxia synergistically enhanced this inhibitory effect,reducing the IC50 to 20.79 μmol·L-1.Conclusion Donepezil downregulates CYP3A4 function through dual mechanisms involving ubiquitin-mediated proteasomal degradation and direct enzymatic inhibition.Hypoxia potentiates this effect,leading to impaired metabolism of CYP3A4 substrate drugs,ele-vated plasma drug concentrations(1.6-2.3-fold in-crease compared to normal metabolic conditions),and an increased risk of QT interval prolongation and other forms of cardiotoxicity.

Aim To investigate the effect of Shenqi Dihuang decoction(SQDH)on henoch-schonlein pur-pura nephritis(HSPN)rats by regulating AMPK/Sirt1/Nrf2 mediated ferroptosis and the possible mech-anism.Methods Thirty SD rats were randomly divid-ed into a control group(Control),HSPN group,SQDH low-dose group(SQDH-L,5.4 g·kg-1),SQDH high-dose group(SQDH-H,21.6 g·kg-1),and SQDH high-dose+AMPK inhibitor group(SQDH-H+CC,20 mg·kg-1),with six rats in each group.Except for the control group,all other groups of rats were injected intraperitoneally with ovalbumin and complete Freund's adjuvant to establish HSPN rat models.After the successful construction of the model,each group of rats was orally administered with the cor-responding dosage or physiological saline once a day for five weeks.HE staining was used to observe the his-topathological changes in renal tissues;immunohisto-chemistry(IHC)was employed to detect the deposition of IgA and IgG in renal tissues;serum biochemical pa-rameters of renal function and urinary protein levels were measured;commercial assay kits were utilized to determine oxidative stress markers and Fe2+levels in renal tissues;Western blot analysis was performed to assess ferroptosis-related proteins and the protein ex-pression of the AMPK/Sirt1/Nrf2 signaling pathway in renal tissues.Results Compared with the control group,the HSPN group showed significant pathological damage in kidney tissue,with significantly increased scores,increased deposition of IgA and IgG in kidney tissue,decreased serum total protein(TP)and albu-min(ALB),and average increases in serum creatinine(Cre),urea nitrogen(BUN),and urinary protein levels(P＜0.05).The levels of MDA,ROS,Fe2+,and ACSL4 protein expression in the kidney tissue sig-nificantly increased,while SOD activity,SLC7A11,GPX4,p-AMPK/AMPK,Sirt1,and Nrf2 protein ex-pression significantly decreased(P＜0.05).Com-pared with the HSPN group,the pathological damage to renal tissue was reduced,IgA and IgG deposition in renal tissue decreased,TP and ALB decreased,Cre,BUN,and urinary protein levels were all reduced(P＜0.05),and the levels of MDA,ROS,Fe2+,and ACSL4 protein expression in renal tissue were signifi-cantly reduced in each dose group of SQDH rats.SOD activity,SLC7A11,GPX4,p-AMPK/AMPK,Sirt1,and Nrf2 protein expression significantly increased(P＜0.05).Compared with the SQDH-H group,the AMPK inhibitor CC could inhibit the AMPK/Sirt1/Nrf2 signaling pathway induced ferroptosis and reverse the protective effect of SQDH on renal injury in HSPN rats.Conclusions SQDH can improve renal injury in HSPN rats,and its mechanism may be related to the activation of AMPK/Sirt1/Nrf2 signaling pathway to in-hibit ferroptosis.

Objective:To examine the impact of outpatient service utilization on hospitalization rates in patients with heart failure,with a focus on identifying the threshold effect,and to provide evidence to support the design of outpatient medical insurance reimbursement policies for heart failure patients.Methods:Using a stratified random sampling method,individual reimbursement data of heart failure pa-tients covered by Urban Employee Basic Medical Insurance in Zhejiang Province from year 2013 to 2017 were extracted.A panel fixed-effects logit regression model and a threshold effect model were applied to analyze the impact of annual outpatient service utilization in the previous year on the hospitalization rate in the current year and to identify the threshold effect.The annual outpatient service utilization indicators included the annual outpatient visits,annual outpatient expenses,annual outpatient drug expenses,and annual outpatient self-expenses within the policy.Hospitalization rate indicators comprised the annual hospitalization rate,rehospitalization rate within 30 days,and rehospitalization rate within 90 days.Results:(1)The study found that an increase in prior-year annual outpatient service utilization led to a decrease in the current-year annual hospitalization rate.However,the effects on the rehospitalization rate within 30 days and rehospitalization rate within 90 days were not statistically significant;(2)The thre-shold effect of prior-year annual outpatient service utilization on the current-year annual hospitalization rate was also identified.When the prior-year annual outpatient visits were less than or equal to the threshold(12 visits),the current-year annual hospitalization rate decreased as the prior-year annual outpatient visits increased and statistically significant,and the regression coefficient was not significant when the prior-year annual outpatient visits were higher than the threshold(12 visits).Correspondingly,the thresholds for annual outpatient expenses and annual outpatient self-expenses within policy in the previous year were 3 342.8 yuan and 736.9 yuan,respectively.Conclusion:There is a threshold effect of prior-year annual outpatient service utilization on the current year's annual hospitalization rate in heart failure patients.These results have important implications for designing outpatient health insurance policies for heart failure patients to improve the patients' utilization of outpatient services and decrease the hospitali-zation rates.Specifically,policymakers should consider the identified thresholds when designing reim-bursement policies for heart failure patients,which may help to optimize the use of medical resources and reduce the burden of medical expenses.