BACKGROUND:Osteoporosis is a high-risk factor for dental implant treatment.The preparation of tissue engineering scaffolds with sustained-release Alendronate and its application in oral implant surgery for osteoporosis patients is a current hot topic in oral bone tissue engineering research.OBJECTIVE:To prepare alendronate/chitosan/polyvinyl alcohol composite hydrogel film and characterize its sustained release properties.METHODS:(1)Chitosan/polyvinyl alcohol composite hydrogel films with varying mass ratios(mass ratios of chitosan and polyvinyl alcohol were 3:7,5:5,and 7:3,respectively),chitosan and polyvinyl alcohol hydrogel films were prepared using a physical crosslinking method.By characterizing the morphology,water contact angle,mechanical properties,swelling rate,and cell compatibility of the hydrogel film,a suitable hydrogel film was screened as a carrier of alendronate.(2)Chitosan/polyvinyl alcohol composite hydrogel films containing 0,0.4,1.2,and 2.0 mg/L alendronate were prepared,and rat bone marrow mesenchymal stem cells were co-cultured with the four groups of hydrogel films.The cytocompatibility of the hydrogel films was detected by CCK-8 assay and CD44 immunofluorescence staining.The drug-loaded chitosan/polyvinyl alcohol composite hydrogel films were immersed in PBS.The drug release performance of the composite hydrogel films was detected by ultraviolet-visible spectroscopy.RESULTS AND CONCLUSION:(1)The characterization results showed that with the increase of the mass of polyvinyl alcohol in the hydrogel film,the structural density of the hydrogel film increased,the porosity decreased,the water contact angle(all within 90°),the elongation at break and the compressive strength increased,and the equilibrium swelling rate decreased.It had no effect on the proliferation of rat bone marrow mesenchymal stem cells.Chitosan hydrogel film could promote the adhesion of rat bone marrow mesenchymal stem cells.The 3:7 and 5:5 ratio composite hydrogel films did not affect the adhesion of rat bone marrow mesenchymal stem cells.Polyvinyl alcohol hydrogel film and 7:3 ratio composite hydrogel film inhibited the adhesion of rat bone marrow mesenchymal stem cells.Based on the above results,the 5:5 composite hydrogel film was selected as the carrier of alendronate.(2)CCK-8 assay results showed that the composite hydrogel film containing 0.4 and 1.2 mg/L alendronate had no cytotoxicity.CD44 immunofluorescence staining results showed that the composite hydrogel film containing 0.4 mg/L alendronate did not affect the adhesion of rat bone marrow mesenchymal stem cells,while the composite hydrogel film containing 1.2 and 2.0 mg/L alendronate inhibited the adhesion of rat bone marrow mesenchymal stem cells.Chitosan/polyvinyl alcohol composite hydrogel film containing 0.4,1.2,and 2.0 mg/L alendronate released alendronate in the first 6 hours,and then released alendronate evenly and stably,with a release time of more than 96 hours.(3)The results showed that the chitosan/polyvinyl alcohol composite hydrogel film with a ratio of 5:5 had good physical and chemical properties and cytocompatibility,and could be used as a sustained-release carrier of alendronate.

Objective To explore the effects and mechanism of Shengxian Yixin Granules in treating ventricular remodeling in rats with myocardial infarction based on the PI3K/AKT signaling pathway.Methods A total of 60 SD rats were randomly selected six rats as the control group,and the remaining 54 rats were used as the modeling group.Sham-operation and left anterior descending coronary artery ligation were performed respectively.The modeled rats were divided into model group,Shengxian Yixin Granules group,740Y-P group and Shengxian Yixin Granules+740Y-P group,and were given corresponding intervention for 28 days.Left ventricular ejection fraction(LVEF)and left ventricular fractional shortening(LVFS)were measured by echocardiography,and left ventricular hypertrophy index was calculated,the myocardial morphology was observed by HE and Masson staining,and the protein expressions of p-PI3K,PI3K,p-AKT and AKT were detected by Western blot,RT-qPCR was used to detect the mRNA expressions of type Ⅰ collagen(Col1)and type Ⅲ collagen(Col3),and ELISA was used to detect the contents of serum cardiac troponin T(cTnT),creatine kinase-MB(CK-MB),Col1 and Col3.Results Compared with the control group,the LVEF and LVFS in the model group significantly decreased(P<0.01),the left ventricular hypertrophy index increased(P<0.01);myocardial cells were arranged disorderly,some cells were necrotic,ruptured and their nuclei were dissolved,with obvious neutrophil infiltration,the collagen fiber significantly increased,the protein expressions of p-PI3K and p-AKT in myocardial tissue significantly increased(P<0.05),and the mRNA expression of Col1 and Col3 significantly increased(P<0.01);the contents of serum cTnT,CK-MB,Col1 and Col3 significantly increased(P<0.05,P<0.01).Compared with the model group,the LVEF and LVFS in Shengxian Yixin Granules group significantly improved(P<0.05,P<0.01),and left ventricular hypertrophy index decreased(P<0.05);myocardial necrosis,neutrophil infiltration and collagen fiber deposition were reduced,the protein expressions of p-PI3K and p-AKT in myocardial tissue significantly decreased(P<0.05),and the mRNA expressions of Col1 and Col3 significantly decreased(P<0.01);the contents of serum cTnT,CK-MB,Col1 and Col3 significantly decreased(P<0.05,P<0.01).LVEF and LVFS in 740Y-P group significantly decreased(P<0.01),and left ventricular hypertrophy index increased(P<0.05);a large number of myocardial cells were necrotic and ruptured,fibers were torn obviously,and many scar tissues were formed,the protein expressions of p-PI3K and p-AKT in myocardial tissue significantly increased(P<0.05),the mRNA expressions of Col1 and Col3 significantly increased(P<0.01);the contents of serum cTnT,CK-MB,Col1 and Col3 significantly increased(P<0.05,P<0.01).Shengxian Yixin Granules+740Y-P could improve the damage of 740Y-P to the heart.Conclusion Shengxian Yixin Granules can improve ventricular remodeling in rats with heart failure,reduce myocardial fibrosis,and improve cardiac function through the PI3K/AKT signaling pathway.

Objective To investigate the distribution and antimicrobial resistance profiles of common pathogens isolated from cerebrospinal fluid(CSF)in CHINET program from 2015 to 2021.Methods The bacterial strains isolated from CSF were identified in accordance with clinical microbiology practice standards.Antimicrobial susceptibility test was conducted using Kirby-Bauer method and automated systems per the unified CHINET protocol.Results A total of 14 014 bacterial strains were isolated from CSF samples from 2015 to 2021,including the strains isolated from inpatients(95.3％)and from outpatient and emergency care patients(4.7％).Overall,19.6％of the isolates were from children and 80.4％were from adults.Gram-positive and Gram-negative bacteria accounted for 68.0％and 32.0％,respectively.Coagulase negative Staphylococcus accounted for 73.0％of the total Gram-positive bacterial isolates.The prevalence of MRSA was 38.2％in children and 45.6％in adults.The prevalence of MRCNS was 67.6％in adults and 69.5％in children.A small number of vancomycin-resistant Enterococcus faecium(2.2％)and linezolid-resistant Enterococcus faecalis(3.1％)were isolated from adult patients.The resistance rates of Escherichia coli and Klebsiella pneumoniae to ceftriaxone were 52.2％and 76.4％in children,70.5％and 63.5％in adults.The prevalence of carbapenem-resistant E.coli and K.pneumoniae(CRKP)was 1.3％and 47.7％in children,6.4％and 47.9％in adults.The prevalence of carbapenem-resistant Acinetobacter baumannii(CRAB)and Pseudomonas aeruginosa(CRPA)was 74.0％and 37.1％in children,81.7％and 39.9％in adults.Conclusions The data derived from antimicrobial resistance surveillance are crucial for clinicians to make evidence-based decisions regarding antibiotic therapy.Attention should be paid to the Gram-negative bacteria,especially CRKP and CRAB in central nervous system(CNS)infections.Ongoing antimicrobial resistance surveillance is helpful for optimizing antibiotic use in CNS infections.

Objective To investigate the antimicrobial resistance of clinical isolates from elderly patients(≥65 years)in major medical institutions across China.Methods Bacterial strains were isolated from elderly patients in 52 hospitals participating in the CHINET Antimicrobial Resistance Surveillance Program during the period from 2015 to 2021.Antimicrobial susceptibility test was carried out by disk diffusion method and automated systems according to the same CHINET protocol.The data were interpreted in accordance with the breakpoints recommended by the Clinical and Laboratory Standards Institute(CLSI)in 2021.Results A total of 514 715 nonduplicate clinical isolates were collected from elderly patients in 52 hospitals from January 1,2015 to December 31,2021.The number of isolates accounted for 34.3％of the total number of clinical isolates from all patients.Overall,21.8％of the 514 715 strains were gram-positive bacteria,and 78.2％were gram-negative bacteria.Majority(90.9％)of the strains were isolated from inpatients.About 42.9％of the strains were isolated from respiratory specimens,and 22.9％were isolated from urine.More than half(60.7％)of the strains were isolated from male patients,and 39.3％isolated from females.About 51.1％of the strains were isolated from patients aged 65-＜75 years.The prevalence of methicillin-resistant strains(MRSA)was 38.8％in 32 190 strains of Staphylococcus aureus.No vancomycin-or linezolid-resistant strains were found.The resistance rate of E.faecalis to most antibiotics was significantly lower than that of Enterococcus faecium,but a few vancomycin-resistant strains(0.2％,1.5％)and linezolid-resistant strains(3.4％,0.3％)were found in E.faecalis and E.faecium.The prevalence of penicillin-susceptible S.pneumoniae(PSSP),penicillin-intermediate S.pneumoniae(PISP),and penicillin-resistant S.pneumoniae(PRSP)was 94.3％,4.0％,and 1.7％in nonmeningitis S.pneumoniae isolates.The resistance rates of Klebsiella spp.(Klebsiella pneumoniae 93.2％)to imipenem and meropenem were 20.9％and 22.3％,respectively.Other Enterobacterales species were highly sensitive to carbapenem antibiotics.Only 1.7％-7.8％of other Enterobacterales strains were resistant to carbapenems.The resistance rates of Acinetobacter spp.(Acinetobacter baumannii 90.6％)to imipenem and meropenem were 68.4％and 70.6％respectively,while 28.5％and 24.3％of P.aeruginosa strains were resistant to imipenem and meropenem,respectively.Conclusions The number of clinical isolates from elderly patients is increasing year by year,especially in the 65-＜75 age group.Respiratory tract isolates were more prevalent in male elderly patients,and urinary tract isolates were more prevalent in female elderly patients.Klebsiella isolates were increasingly resistant to multiple antimicrobial agents,especially carbapenems.Antimicrobial resistance surveillance is helpful for accurate empirical antimicrobial therapy in elderly patients.

Objective To examine the changing prevalence and antimicrobial resistance profiles of Burkholderia cepacia in 52 hospitals across China from 2015 to 2021.Methods A total of 9 261 strains of B.cepacia were collected from 52 hospitals between January 1,2015 and December 31,2021.Antimicrobial susceptibility of the strains was tested using Kirby-Bauer method or automated antimicrobial susceptibility testing systems according to a unified protocol.The results were interpreted according to the breakpoints released in the Clinical & Laboratory Standards Institute(CLSI)guidelines(2023 edition).Results A total of 9 261 strains of B.cepacia were isolated from all age groups,especially elderly patients.The proportion was 11.1％(1 032 strains)in children,significantly lower than the proportion in adults.About half(46.5％,4 310/9 261)of the strains were isolated from patients at least 60 years old and 42.3％(3 919/9 261)of the strains were isolated from young adults.Most isolates(71.1％)were isolated from sputum and respiratory secretions,followed by urine(10.7％)and blood samples(8.1％).B.cepacia isolates were highly susceptible to the five antimicrobial agents recommended in the CLSI M100 document(33rd edition,2023).B.cepacia isolates showed relatively higher resistance rates to meropenem and levofloxacin.However,the resistance rates to ceftazidime,trimethoprim-sulfamethoxazole,and minocycline remained below 8.1％.The percentage of B.cepacia strains resistant to levofloxacin was the highest compared to other antibiotics in any of the three age groups(from 12.4％in the patients＜18 years old to 20.6％in the patients aged 60 years or older).Conclusions B.cepacia is one of the clinically important non-fermenting gram-negative bacteria.Accurate and timely reporting of antimicrobial susceptibility test results and ongoing antimicrobial resistance surveillance are helpful for rational prescription of antimicrobial agents and proper prevention and control of nosocomial infections.

Objective: To explore the effect of YTH domain family protein 1(YTHDF1) on the activation, proliferation and migration of hepatic stellate cells(HSCs) by regulating mitochondrial fission mediated by mitochondrial fission protein 1(Fis1). Methods: The mouse hepatic stellate cell line JS-1 was treated with 5 ng/ml TGF-β1 for 24 h to induce its activation and proliferation, andYTHDF1-siRNA was used to construct aYTHDF1silencing model.The experiment was divided into Control group, TGF-β1 group, TGF-β1+si-NC group and TGF-β1+si-YTHDF1 group.Expression changes ofYTHDF1,Fis1and key indicators of fibrosis, type Ⅰ collagen(CollagenⅠ) and α-smooth muscle actin(α-SMA) were detected through reverse transcription quantitative polymerase chain reaction(RT-qPCR) and Western blot; CCK-8 was used to detect cell proliferation ability; Transwell migration assay and cell scratch assay were used to detect cell migration ability; immunofluorescence staining experiment was used to detect the effect ofYTHDF1onFis1-mediated mitochondrial fission; finally, JC-1 staining was used to experimentally detect the effect ofYTHDF1on mitochondrial membrane potential. Results: Compared with the Control group, RT-qPCR and Western blot experimental results showed that the expression ofYTHDF1andFis1increased in the TGF-β1 group(P<0.05,P<0.01;P<0.000 1), as well as the fibrosis markersCollagenⅠand the expression level of α-SMA increased(P<0.01;P<0.001,P<0.000 1); while adding CCK-8, the experimental results showed that the proliferation ability of HSCs in the TGF-β1 group was enhanced(P<0.000 1); Transwell experimental results showed that the migration ability of HSCs in the TGF-β1 group was enhanced(P<0.01); the cell scratch experiment results showed that the migration ability of HSCs in the TGF-β1 group was enhanced(P<0.000 1); the immunofluorescence experiment results showed that the TGF-β1 group Mito-Tracker Red staining andFis1co-localization signal increased(P<0.05); JC-1 staining experiment results showed that the mitochondrial membrane potential increased in the TGF-β1 group(P<0.01). Compared with the TGF-β1+si-NC group, RT-qPCR and Western blot experimental results showed that the expression ofYTHDF1andFis1in the TGF-β1+si-YTHDF1 group was reduced(P<0.01;P<0.001), and fibrosis markers the levels ofCollagenⅠandα-SMAwere reduced(P<0.01;P<0.001,P<0.01).CCK-8 experimental results showed that the proliferation ability of HSCs in the TGF-β1+si-YTHDF1 group was weakened(P<0.000 1); Transwell experiment results showed that the migration ability of HSCs in the TGF-β1+si-YTHDF1 group was weakened(P<0.001); cell scratch experiment results showed that the migration ability of HSCs in the TGF-β1+si-YTHDF1 group was weakened(P<0.000 1); immunofluorescence experiment results showed that the Mito-Tracker Red staining andFis1co-localization signal decreased in the TGF-β1+si-YTHDF1 group(P<0.01); JC-1 staining experiment results showed that mitochondrial membrane potential decreased in the TGF-β1+si-YTHDF1 group(P<0.05). Conclusion YTHDF1promotes the activation, proliferation and migration capabilities of HSCs by positively regulatingFis1-mediated mitochondrial fission. This suggests thatYTHDF1may be a key gene involved in regulating the activation, proliferation and migration of HSCs.

Objective To establish a stable,reliable,and clinically relevant porcine model of endotoxin-induced acute respiratory distress syndrome(ARDS).Methods Ten 8-month-old male Bama minipigs were deeply sedated,followed by invasive mechanical ventilation and electrocardiographic monitoring.Lipopolysaccharide(LPS)was intravenously pumped at 600 μg/(kg·h)for 3 hours,then maintained at 15 μg/(kg·h)thereafter.Dynamic monitoring was performed at five time points after LPS injection(LPS 0,1,3,5,and 8 h),including arterial blood gas analysis and chest computed tomography(CT)scans.Pathological examination of lung tissues obtained via bronchoscopic biopsy(HE staining and transmission electron microscopy)was conducted.These indicators were comprehensively used to evaluate the success of the animal model.Results At 5 hours after LPS administration,8 minipigs developed symptoms such as skin cyanosis,elevated body temperature,and respiratory distress.The oxygenation index decreased to<300 mmHg.Chest CT scans showed diffuse pulmonary infiltrates.Histopathology revealed alveolar edema and hyaline membrane formation.Transmission electron microscopy demonstrated disruption of pulmonary blood-air barrier,depletion of lamellar bodies in type Ⅱ pneumocytes,inflammatory cell infiltration,and exudation of plasma proteins and fibrin.Compared with LPS 0 h,at LPS 8 h,the oxygenation index and arterial blood pH were significantly decreased(P<0.001),while blood lactic acid and serum potassium were significantly increased(P<0.05);serum calcium and base excess were significantly decreased(P<0.05),and the lung injury score based on HE-stained lung sections was significantly increased(P<0.01).Conclusion The porcine ARDS model established by continuous LPS injection can dynamically simulate the pathophysiological characteristics and typical pathological manifestations of clinical septic ARDS,making it an effective tool to study the pathogenesis,prevention,and treatment strategies of septic ARDS.

Objective To examine the changing prevalence and antimicrobial resistance profiles of Burkholderia cepacia in 52 hospitals across China from 2015 to 2021.Methods A total of 9 261 strains of B.cepacia were collected from 52 hospitals between January 1,2015 and December 31,2021.Antimicrobial susceptibility of the strains was tested using Kirby-Bauer method or automated antimicrobial susceptibility testing systems according to a unified protocol.The results were interpreted according to the breakpoints released in the Clinical & Laboratory Standards Institute(CLSI)guidelines(2023 edition).Results A total of 9 261 strains of B.cepacia were isolated from all age groups,especially elderly patients.The proportion was 11.1％(1 032 strains)in children,significantly lower than the proportion in adults.About half(46.5％,4 310/9 261)of the strains were isolated from patients at least 60 years old and 42.3％(3 919/9 261)of the strains were isolated from young adults.Most isolates(71.1％)were isolated from sputum and respiratory secretions,followed by urine(10.7％)and blood samples(8.1％).B.cepacia isolates were highly susceptible to the five antimicrobial agents recommended in the CLSI M100 document(33rd edition,2023).B.cepacia isolates showed relatively higher resistance rates to meropenem and levofloxacin.However,the resistance rates to ceftazidime,trimethoprim-sulfamethoxazole,and minocycline remained below 8.1％.The percentage of B.cepacia strains resistant to levofloxacin was the highest compared to other antibiotics in any of the three age groups(from 12.4％in the patients＜18 years old to 20.6％in the patients aged 60 years or older).Conclusions B.cepacia is one of the clinically important non-fermenting gram-negative bacteria.Accurate and timely reporting of antimicrobial susceptibility test results and ongoing antimicrobial resistance surveillance are helpful for rational prescription of antimicrobial agents and proper prevention and control of nosocomial infections.

Objective To summarize the changing prevalence of carbapenem resistance in Enterobacterales based on the data of CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021 for improving antimicrobial treatment in clinical practice.Methods Antimicrobial susceptibility testing was performed using a commercial automated susceptibility testing system according to the unified CHINET protocol.The results were interpreted according to the breakpoints of the Clinical & Laboratory Standards Institute(CLSI)M100 31st ed in 2021.Results Over the seven-year period(2015-2021),the overall prevalence of carbapenem-resistant Enterobacterales(CRE)was 9.43％(62 342/661 235).The prevalence of CRE strains in Klebsiella pneumoniae,Citrobacter freundii,and Enterobacter cloacae was 22.38％,9.73％,and 8.47％,respectively.The prevalence of CRE strains in Escherichia coli was 1.99％.A few CRE strains were also identified in Salmonella and Shigella.The CRE strains were mainly isolated from respiratory specimens(44.23±2.80)％,followed by blood(20.88±3.40)％and urine(18.40±3.45)％.Intensive care units(ICUs)were the major source of the CRE strains(27.43±5.20)％.CRE strains were resistant to all the β-lactam antibiotics tested and most non-β-lactam antimicrobial agents.The CRE strains were relatively susceptible to tigecycline and polymyxins with low resistance rates.Conclusions The prevalence of CRE strains was increasing from 2015 to 2021.CRE strains were highly resistant to most of the antibacterial drugs used in clinical practice.Clinicians should prescribe antimicrobial agents rationally.Hospitals should strengthen antibiotic stewardship in key clinical settings such as ICUs,and take effective infection control measures to curb CRE outbreak and epidemic in hospitals.

Objective To characterize the changing species distribution and antibiotic resistance profiles of respiratory isolates in hospitals participating in the CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021.Methods Commercial automated antimicrobial susceptibility testing systems and disk diffusion method were used to test the susceptibility of respiratory bacterial isolates to antimicrobial agents following the standardized technical protocol established by the CHINET program.Results A total of 589 746 respiratory isolates were collected from 2015 to 2021.Overall,82.6％of the isolates were Gram-negative bacteria and 17.4％were Gram-positive bacteria.The bacterial isolates from outpatients and inpatients accounted for(6.0±0.9)％and(94.0±0.1)％,respectively.The top microorganisms were Klebsiella spp.,Acinetobacter spp.,Pseudomonas aeruginosa,Staphylococcus aureus,Haemophilus spp.,Stenotrophomonas maltophilia,Escherichia coli,and Streptococcus pneumoniae.Each microorganism was isolated from significantly more males than from females(P＜0.05).The overall prevalence of methicillin-resistant S.aureus(MRSA)was 39.9％.The prevalence of penicillin-resistant S.pneumoniae was 1.4％.The prevalence of extended-spectrum β-lactamase(ESBL)-producing E.coli and K.pneumoniae was 67.8％and 41.3％,respectively.The overall prevalence of carbapenem-resistant E.coli,K.pneumoniae,Enterobacter cloacae,Pseudomonas aeruginosa,and Acinetobacter baumannii was 3.7％,20.8％,9.4％,29.8％,and 73.3％,respectively.The prevalence of β-lactamase was 96.1％in Moraxella catarrhalis and 60.0％in Haemophilus influenzae.The H.influenzae isolates from children(＜18 years)showed significantly higher resistance rates to β-lactam antibiotics than the isolates from adults(P＜0.05).Conclusions Gram-negative bacteria are still predominant in respiratory isolates associated with serious antibiotic resistance.Antimicrobial resistance surveillance should be strengthened in clinical practice to support accurate etiological diagnosis and appropriate antimicrobial therapy based on antimicrobial susceptibility testing results.