BACKGROUND:Bone tissue loss caused by tumors and trauma can have an adverse effect on postoperative rehabilitation.Therefore,scaffold materials are usually implanted during treatment.However,the existing implant materials are relatively simple and lack antibacterial properties.Early implantation may lead to iatrogenic autoinfection and have an adverse effect on osteogenesis.OBJECTIVE:To construct a KR-12-a5 polypeptide-nanohydroxyapatite-small intestinal submucosa composite scaffold and evaluate its feasibility as a material for promoting bone defect repair.METHODS:The small intestinal submucosa scaffold and the small intestinal submucosa scaffold containing 25,50,and 100 mg/mL nanohydroxyapatite(referred to as nHA-SIS scaffold)were prepared by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride/N-hydroxysuccinimide cross-linking method.The appropriate scaffold was screened for subsequent experiments by mechanical property testing.The antibacterial properties of KR-12-a5 polypeptide solution against Staphylococcus aureus,Streptococcus gordonii,and Fusobacterium nucleatum were detected.The nHA-SIS scaffolds were immersed in 250,500,and 1 000 μg/mL KR-12-a5 peptide solutions for 24 hours,and then freeze-dried to obtain peptide-loaded nanohydroxyapatite-porcine small intestinal submucosa composite scaffolds(denoted as P-nHA-SIS scaffolds).The sustained-release properties of the three groups of scaffolds were characterized.The nHA-SIS scaffolds and the three groups of P-nHA-SIS scaffolds were co-cultured with Staphylococcus aureus,Streptococcus gordonii,and Fusobacterium nucleatum for 24 hours or 48 hours.The scaffolds with strong antibacterial ability were screened by live and dead bacteria staining and scanning electron microscopy for subsequent experiments.The degradation properties and water absorption rates of the uncross-linked small intestinal submucosa scaffolds,cross-linked small intestinal submucosa scaffolds,nHA-SIS scaffolds,and P-nHA-SIS scaffolds were characterized.The extracts of cross-linked small intestinal submucosal scaffolds,nHA-SIS scaffolds,and P-nHA-SIS scaffolds were co-cultured with MC3T3-E1 cells.CCK-8 assay and live-dead cell staining were performed.The effects of the extracts of the three scaffolds on the migration of MC3T3-E1 cells were detected by Transwell chamber assay.RESULTS AND CONCLUSION:(1)The elastic modulus and compressive strength of 25,50,and 100 mg/mL nHA-SIS scaffolds were higher than those of small intestinal submucosal scaffolds(P＜0.05),among which the elastic modulus and compressive strength of 25 mg/mL nHA-SIS scaffolds were the highest,and this group of scaffolds were selected for subsequent experiments to load peptides.(2)KR-12-a5 peptide had strong antibacterial activity against common bacteria in bone defects(Staphylococcus aureus,Streptococcus gordonii,and Fusobacterium nucleatum).The three groups of P-nHA-SIS scaffolds all had sustained release properties.With the increase of peptide mass concentration,the antibacterial property of P-nHA-SIS scaffold was enhanced.Among them,the P-nHA-SIS scaffold loaded with 500 μg/mL peptide had achieved a satisfactory antibacterial effect,and this group of scaffolds would be selected in the future.(3)The degradation rate of the three groups of cross-linked scaffolds was lower than that of the uncross-linked scaffolds,and the water absorption rate was greater than that of the uncross-linked scaffolds.P-nHA-SIS scaffolds could promote the proliferation and migration of MC3T3-E1 cells without affecting the activity of MC3T3-E1 cells.(4)The results show that P-nHA-SIS scaffolds have strong antibacterial properties and the ability to promote the proliferation and migration of MC3T3-E1 cells,and are expected to be used in bone defect repair.

BACKGROUND:Bone tissue loss caused by tumors and trauma can have an adverse effect on postoperative rehabilitation.Therefore,scaffold materials are usually implanted during treatment.However,the existing implant materials are relatively simple and lack antibacterial properties.Early implantation may lead to iatrogenic autoinfection and have an adverse effect on osteogenesis.OBJECTIVE:To construct a KR-12-a5 polypeptide-nanohydroxyapatite-small intestinal submucosa composite scaffold and evaluate its feasibility as a material for promoting bone defect repair.METHODS:The small intestinal submucosa scaffold and the small intestinal submucosa scaffold containing 25,50,and 100 mg/mL nanohydroxyapatite(referred to as nHA-SIS scaffold)were prepared by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride/N-hydroxysuccinimide cross-linking method.The appropriate scaffold was screened for subsequent experiments by mechanical property testing.The antibacterial properties of KR-12-a5 polypeptide solution against Staphylococcus aureus,Streptococcus gordonii,and Fusobacterium nucleatum were detected.The nHA-SIS scaffolds were immersed in 250,500,and 1 000 μg/mL KR-12-a5 peptide solutions for 24 hours,and then freeze-dried to obtain peptide-loaded nanohydroxyapatite-porcine small intestinal submucosa composite scaffolds(denoted as P-nHA-SIS scaffolds).The sustained-release properties of the three groups of scaffolds were characterized.The nHA-SIS scaffolds and the three groups of P-nHA-SIS scaffolds were co-cultured with Staphylococcus aureus,Streptococcus gordonii,and Fusobacterium nucleatum for 24 hours or 48 hours.The scaffolds with strong antibacterial ability were screened by live and dead bacteria staining and scanning electron microscopy for subsequent experiments.The degradation properties and water absorption rates of the uncross-linked small intestinal submucosa scaffolds,cross-linked small intestinal submucosa scaffolds,nHA-SIS scaffolds,and P-nHA-SIS scaffolds were characterized.The extracts of cross-linked small intestinal submucosal scaffolds,nHA-SIS scaffolds,and P-nHA-SIS scaffolds were co-cultured with MC3T3-E1 cells.CCK-8 assay and live-dead cell staining were performed.The effects of the extracts of the three scaffolds on the migration of MC3T3-E1 cells were detected by Transwell chamber assay.RESULTS AND CONCLUSION:(1)The elastic modulus and compressive strength of 25,50,and 100 mg/mL nHA-SIS scaffolds were higher than those of small intestinal submucosal scaffolds(P＜0.05),among which the elastic modulus and compressive strength of 25 mg/mL nHA-SIS scaffolds were the highest,and this group of scaffolds were selected for subsequent experiments to load peptides.(2)KR-12-a5 peptide had strong antibacterial activity against common bacteria in bone defects(Staphylococcus aureus,Streptococcus gordonii,and Fusobacterium nucleatum).The three groups of P-nHA-SIS scaffolds all had sustained release properties.With the increase of peptide mass concentration,the antibacterial property of P-nHA-SIS scaffold was enhanced.Among them,the P-nHA-SIS scaffold loaded with 500 μg/mL peptide had achieved a satisfactory antibacterial effect,and this group of scaffolds would be selected in the future.(3)The degradation rate of the three groups of cross-linked scaffolds was lower than that of the uncross-linked scaffolds,and the water absorption rate was greater than that of the uncross-linked scaffolds.P-nHA-SIS scaffolds could promote the proliferation and migration of MC3T3-E1 cells without affecting the activity of MC3T3-E1 cells.(4)The results show that P-nHA-SIS scaffolds have strong antibacterial properties and the ability to promote the proliferation and migration of MC3T3-E1 cells,and are expected to be used in bone defect repair.

OBJECTIVE: To explore the protective effects and underlying mechanisms of H ₂S against lipid peroxidation-mediated carbonyl stress in the uranium-treated NRK-52E cells. METHODS: Cell viability was evaluated using CCK-8 assay. Apoptosis was measured using flow cytometry. Reagent kits were used to detect carbonyl stress markers malondialdehyde, 4-hydroxynonenal, thiobarbituric acid reactive substances, and protein carbonylation. Aldehyde-protein adduct formation and alcohol dehydrogenase, aldehyde dehydrogenase 2, aldo-keto reductase, nuclear factor E2-related factor 2 (Nrf2), and cystathionine β-synthase (CBS) expression were determined using western blotting or real-time PCR. Sulforaphane (SFP) was used to activate Nrf2. RNA interference was used to inhibit CBS expression. RESULTS: GYY4137 (an H ₂S donor) pretreatment significantly reversed the uranium-induced increase in carbonyl stress markers and aldehyde-protein adducts. GYY4137 effectively restored the uranium-decreased Nrf2 expression, nuclear translocation, and ratio of nuclear to cytoplasmic Nrf2, accompanied by a reversal of the uranium-decreased expression of CBS and aldehyde-metabolizing enzymes. The application of CBS siRNA efficiently abrogated the SFP-enhanced effects on the expression of CBS, Nrf2 activation, nuclear translocation, and ratio of nuclear to cytoplasmic Nrf2 and concomitantly reversed the SFP-enhanced effects of the uranium-induced mRNA expression of aldehyde-metabolizing enzymes. Simultaneously, CBS siRNA reversed the SFP-mediated alleviation of the uranium-induced increase in reactive aldehyde levels, apoptosis rates, and uranium-induced cell viability. CONCLUSION H ₂S induces Nrf2 activation and nuclear translocation, which modulates the expression of aldehyde-metabolizing enzymes and the CBS/H ₂S axis. Simultaneously, the Nrf2-controlled CBS/H ₂S axis may at least partially promote Nrf2 activation and nuclear translocation. These events form a cycle-regulating mode through which H ₂S attenuates the carbonyl stress-mediated NRK-52E cytotoxicity triggered by uranium.
NF-E2-Related Factor 2/genetics* ; Animals ; Hydrogen Sulfide/pharmacology* ; Rats ; Signal Transduction/drug effects* ; Lipid Peroxidation/drug effects* ; Cell Line ; Uranium/toxicity* ; Antioxidant Response Elements ; Kidney/metabolism* ; Oxidative Stress/drug effects* ; Cell Survival/drug effects* ; Apoptosis/drug effects*

The scientific research and innovation capabilities of medical students are intrinsically linked to the sustained and high-quality development of national healthcare initiatives.Cultivating outstanding medi-cal students with independent scientific capabilities and innovative consciousness is a critical component in the education and training of high-level medical professionals.Our investigation revealed that within the imperfections of the cultivating model,some faculty and students at medical schools have an insufficient understanding of scientific research and innovation and lack motivation for engaging in such activities,which hinder the progression of scientific research activities.Consequently,we initiated a teaching practice and exploratory study on the"tutorial system"aimed at fostering medical students'scientific research and innovation abilities.Based on the principle of"research informing teaching,teaching and research advan-cing together,"this study implements a"tutorial system"coordinated by tutors,supplemented by graduate and undergraduate student mentors,to cultivate innovative thinking,stimulate interest in scientific re-search,and enhance practical and research skills among medical students.Through collaborative efforts within"scientific research innovation teams,"various educational methods—including preliminary re-search,in-class and extracurricular activities,intra-group and inter-group interactions,and theoretical and practical applications—are employed to improve and strengthen the cultivation of medical students'scientif-ic research and innovation abilities.This study aims to provide valuable references for optimizing medical education management systems and enhancing the quality of medical student training.

Aim To explore the effects of D-limonene on the steatosis of primary mouse hepatocytes and its potential mechanism of action.Methods Oleic acid-induced steatosis in primary mouse hepatocytes was used as a model to observe the effects of D-limonene on cell viability,cellular lipid content,and intracellular expression of proteins such as AMP-activated protein kinase(AMPK),acetyl-coenzyme A carboxylase 1(ACC1),and carnitine palmitoyl transferase 1A(CPT1A).Results It was found that a low dose of D-limonene could effectively enhance the viability of primary mouse hepatocytes.When oleic acid at a con-centration of 300 μmol·L-1 successfully induced steatosis in primary mouse hepatocytes,D-limonene re-duced the lipid content of the cells,and D-limonene up-regulated the cellular AMPK expression level,down-regulated the cellular ACC1 and fatty acid synthetase(FAS)expression levels,which in turn promoted the overexpression of CPT1A.Conclusions D-limonene has the effect of reducing lipid deposition in primary mouse hepatocytes,and the mechanisms may be related to the activation of AMPK,the inhibitions of ACC1 and FAS,and the up-regulation of CPT1A protein expres-sion level.

A quadruplex RT-qPCR method was developed for rapid identification and diagnosis of transmissible gastroenteritis virus(TGEV)of swine,porcine epidemic diarrhea virus(PEDV),porcine deltacorona virus(PDCoV),and porcine rotavirus type A(PoRVA).The full-length sequences of PEDV(77 strains),TGEV(63 strains),PDCoV(17 strains)that are prevalent in China,as well as the 85 VP6 gene sequences of PoRVA,were downloaded from the NCBI database for homology analysis.Based on the relatively conserved sequences,the corresponding primers and probes for each virus were designed and used to establish the quadruplex RT-qPCR method.After optimization of the probes and the reaction conditions,the specificity,sensitivity,and repeatability were determined.Using the established method,109 clinical samples of diarrhea were tested and further compared with the results by standard method.The results showed that the quadruplex RT-qPCR method established in this experiment has good amplification effect,with the C,value linearly correlated with the copies of templates(R2＞0.99).Specificity assay demonstrated that the quadruplex RT-qPCR method can identify TGEV,PEDV,PDCoV,PRoVA strains,and do not de-tect African swine fever virus(ASFV),porcine circovirus type 2(PCV2),porcine reproductive and respiratory syndrome virus(PRRSV),classical swine fever virus(CSFV),pseudorabies virus(PRV)and other epidemic viruses.Sensitivity assay showed that the detection limits for TGEV,PEDV,PDCoV and PoRVA were 10,20,20 and 50 copies/μL,respectively.The method exhibits excellent reproducibility,with coefficients of variation(Cv)for both intra-and inter-assay repli-cates being less than 1％.Detection of 109 samples of diarrhea by this method yielded the coinci-dence rate of 100％with the industry standard,indicating high practical applicability.The devel-oped method possesses the advantages of strong strain compatibility,high sensitivity,strong speci-ficity,good repeatability and stability.It is suitable for virus diagnosis and large-scale clinical sam-ple testing,providing technical support for disease prevention and control as well as epidemiologi-cal investigation.

Objective To analyze the relationship of silent information regulator 2(SIRT2)with the occurrence and severity of cognitive impairment in patients with acute cerebral infarction(ACI).Methods Clinical data of 150 ACI patients(study group)complicated with cognitive im-pairment admitted in our hospital from May 2022 to May 2024 were collected and analyzed retro-spectively.According to the severity of cognitive impairment,they were divided into mild(45 cases),moderate(66 cases)and severe subgroups(39 cases).Another 125 ACI patients without cognitive dysfunction admitted in our hospital during the same period were recruited and served as the control group.Spearman correlation analysis was adopted to analyze the correlation between serum SIRT2 level and cognitive impairment and disease severity.ROC curve analysis was applied to assess the value of serum SIRT2 level for cognitive impairment and its severity,and its area under the curve(AUC)was calculated.Results The serum SIRT2 level was significantly higher in the study group than the control group(20.38±5.19 mg/L vs 14.66±4.49 mg/L,P＜0.05),so was in the severe subgroup than the moderate and mild subgroups,and in the moderate subgroup than the mild subgroup(P＜0.05).Spearman analysis showed that serum SIRT2 level was posi-tively correlated with the occurrence and severity of cognitive impairment(r=0.510,r=0.527,P＜0.01).ROC curve analysis indicated that the AUC value of serum SIRT2 level in evaluating the occurrence of cognitive impairment was 0.796(95％CI:0.743-0.842),with a cutoff value,sensitivity and specificity of 19.0 mg/L,63.33％and 84.00％,respectively,and the AUC value was 0.747(95％CI:0.655-0.824)in assessing the severity of cognitive impairment,with a cutoff value,sensitivity and specificity of 17.2 mg/L,75.76％and 71.11％,respectively(P＜0.05).Conclusion Serum SIRT2 level is closely associated with the occurrence and severity of cognitive impairment in ACI patients.

Liver fibrosis is a key pathological process in the progression of chronic liver disease, and its early stage and accurate diagnosis are crucial for improving patient prognosis. In recent years, the non-invasive diagnosis of liver fibrosis has gradually shifted from the traditional model based on conventional serological indicators to an evaluation system that integrates new biomarkers and multi-omics technologies. This article systematically reviews the evolution of the serological evaluation system for non-invasive diagnosis of liver fibrosis, introduces the application progress of serological models, novel biomarkers, and the introduction of multimodal integration and artificial intelligence technology, and analyzes their advantages and limitations, with aim of providing novel ideas for achieving accurate diagnosis and assisting in clinical management of patients.

The scientific research and innovation capabilities of medical students are intrinsically linked to the sustained and high-quality development of national healthcare initiatives.Cultivating outstanding medi-cal students with independent scientific capabilities and innovative consciousness is a critical component in the education and training of high-level medical professionals.Our investigation revealed that within the imperfections of the cultivating model,some faculty and students at medical schools have an insufficient understanding of scientific research and innovation and lack motivation for engaging in such activities,which hinder the progression of scientific research activities.Consequently,we initiated a teaching practice and exploratory study on the"tutorial system"aimed at fostering medical students'scientific research and innovation abilities.Based on the principle of"research informing teaching,teaching and research advan-cing together,"this study implements a"tutorial system"coordinated by tutors,supplemented by graduate and undergraduate student mentors,to cultivate innovative thinking,stimulate interest in scientific re-search,and enhance practical and research skills among medical students.Through collaborative efforts within"scientific research innovation teams,"various educational methods—including preliminary re-search,in-class and extracurricular activities,intra-group and inter-group interactions,and theoretical and practical applications—are employed to improve and strengthen the cultivation of medical students'scientif-ic research and innovation abilities.This study aims to provide valuable references for optimizing medical education management systems and enhancing the quality of medical student training.

Objective Aimed at investigating the effect and molecular mechanism of artemisinin on hemo-dynamics and vascular remodeling in monocrotaline(MCT)-induced pulmonary arterial hypertension(PAH)rats.Methods 30 male SD rats were randomly divided into 3 groups(n=10):control group,MCT-induced PAH group(MCT group,60 mg/kg)and artemisinin intervention group(50 mg/kg).At 28 days after modeling,the right ventricular systolic pressure(RVSP),mean pulmonary artery pressure(mPAP),heart rate and right ventricular hypertrophy index(RVHI)were measured to evaluate the development of PAH.HE staining and α-SMA immuno-histochemistry were used to observe the morphology and assess muscularization of pulmonary arterioles,and the percentage of medial wall thickness(WT%),the percentage of vascular wall area(WA%)and the proportion of muscular vessels were calculated to evaluate the degree of pulmonary vascular remodeling.The mRNA and protein levels of HIF-1α and LDHA were detected by real-time PCR and Western blot,respectively.Pyruvate and lactate concentration in lung tissue was measured using pyruvate and lactateassay kit.Results Compared with the control group,the RVSP,mPAP,heart rate and RVHI were significantly increased in MCT-induced PAH rats(all P<0.05).Histological analysis showed that the increasedmedial wall thickness of small pulmonary arteries and vascular muscularization were observed in MCT-treated rats compared with control rats.WT%,WA%and muscularization degrees of pulmonary arterioles were higher in MCT-treated rats than those in the control group(all P<0.05),suggesting successful construction of PAH model.Compared with the MCT group,the RVSP,mPAP,heart rate and RVHI decreased in the rats treated with artemisinin(all P<0.05),accompanied with lower WT%and WA%(P<0.05),and muscularization of pulmonary arterioles was improved(P<0.05).Further study showed the mRNA and protein levels ofHIF-1α and LDHA in lung tissue of MCT-induced PAH rats were higher than those in the control group,the content of lactate and pyruvate and the ratio of lactate to pyruvate were higher than that in the control group(all P<0.05).However,the mRNA and protein levels of HIF-1α and LDHA in lung tissue of rats treated with artemisinin were lower than those in the MCT group,the content of lactate and pyruvate and the ratio of lactate to pyruvate were lower than that in the MCT group(all P<0.05).Conclusion Artemisinin improves hemodynamic and pulmonary vascular remodeling in PAH rats through inhibiting HIF-1α/LDHA signaling pathway-mediated glycolysis.