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.

With the rapid development of artificial intelligence(AI),how to digitize the teaching of Medical Immunology is a new challenge posed by the times and education.This study is based on the advanced teaching model of Medical Immunology,which includes lectures-PAD class-flipped classrooms-expert lecture.By introducing knowledge mapping and AI teaching assistant into the entire learning process,the students not only deepen their understanding of the knowledge system of Medical Immunology,but also ex-ercise their ability to apply immunological knowledge to solve practical clinical problems,enhance their self-learning ability,expres-sion ability,communication ability,on-site performance ability,and cultivate a spirit of unity,cooperation,and exploration.The practice of empowering Medical Immunology teaching with digital intelligence achieves the integration of theory and application,the linkage between in class and out of class teaching,the connection between commonalities and individualities,and the union of abili-ties and qualities in Medical Immunology teaching.It also provides practical basis for exploring the implementation path of digital intel-ligence empowerment in Medical Immunology teaching.

Objective:To analyze the differences in pediatric CT radiation dose and scanning parameter Settings between children's specialized hospitals and general hospitals, and to provide reference for the optimization strategy of pediatric CT radiation dose.Methods:From July to August 2022, a stratified sampling method was used to select 7 comprehensive hospitals and 2 children's hospitals in Tianjin, and on-site survey was conducted to collect the dose data of children's head, chest, and abdomen and pelvic CT examinations in these hospitals. The Wilcoxon rank sum test was used to analyze the differences in CTDI vol and DLP of the same age group and examination site among different types of hospitals, and the stepwise regression analysis method was used to analyze the effects of age, examination site, and scanning parameters on radiation dose CTDI vol and DLP. Results:The CTDI vol and DLP of head (1-<5, 5-<10, 10-<15 years old group), chest (5-<10, 10-<15 years old group) and abdomen (1-<5, 5-<10, 10-<15 years old group) in children's specialized hospitals were lower than those in general hospitals (head, 1-<5, 5-<10, 10-<15 years old group, CTDI vol: Z=-9.32, -6.17, -9.86, P<0.001, DLP, Z=-4.41, -4.14, -5.76, P<0.001; chest, 5-<10, 10-<15 years old group, CTDI vol: Z=-3.84, -5.35, P<0.001, DLP, Z=-3.59, -4.63, P<0.001; abdomen, 1-<5、5-<10 and 10-<15 years old group, CTDI vol: Z=-7.88, -7.78, -8.53, P<0.001, DLP, Z=-7.24, -5.92, -3.44, P<0.001). The CT radiation dose in children was positively correlated with age, tube voltage, tube current time product and scan length, and negatively correlated with pitch and hospital type (general hospital and children's hospital) . Conclusion:There are some differences in the CT radiation dose and scanning parameters between children's hospitals and general hospitals. The results indicate that there is still much room for improvement in the optimization of radiation dose in pediatric CT examination.

Objective To compare the impact of NaClO and EDTA pretreatment on the enamel surfaces pore exposure rate,resin in-filtration effectiveness and shear bond strength between the enamel white spot lesions(WSLs)and resin composite.Methods A total of 104 sound premolars were selected for the study.4 mm×4 mm×2 mm enamel blocks from 64 sound premolars were cut in the center of the buccal surfaces of the teeth.All blocks were randomly divided into five groups:group SE(sound enamels as negative control);group DE(enamel blocks demineralised as positive control);group RI(resin infiltration);group N/RI(5.25％NaClO pretreatment and resin infiltration)and group E/RI(17％EDTA pretreatment and resin infiltration).The pore exposure rate of enamel surfaces and resin penetration depths were observed by scanning electron microscopy(SEM)and confocallaser scanning microscopy(CLSM)in each group.The remaining 40 premolars were cut from the cervical roots and the residual crowns were embedded in self-condensing resin ma-terial(buccal surfaces of the enamel exposed only).According to the grouping information,the samples were given the corresponding pretreatments and resin infiltration respectively and were bonded with a cylindrical resin cylinder on the buccal enamel surface for shear bond test.The shear bond strength and fracture modes were recorded and analyzed in each group.Results Compared to group RI,the pore exposure rate of the enamel surface,resin penetration depths,and percentage of resin penetration area in the N/RI and E/RI groups were significantly increased(P＜0.05).The shear bond strength of the samples in group SE was the highest,and the lowest in group DE.Compared to group DE,the shear bond strength in groups RI,N/RI,and E/RI was significantly increased(P＜0.05).Con-clusion Enamel surface pretreatment with 5.25％NaClO or 17％EDTA has been demonstrated to effectively enhance the enamel pore exposure rate,resin penetration depth and the shear bond strength between WSLs and resin composite.

Objective To develop an ICU patient care difficulty index based on psychosocial factors and to evaluate its reliability and validity,thereby providing a comprehensive tool for assessing the difficulties in ICU patient care.Methods Guided by Guarinoni theory,an index system was developed through systematic literature reviews,semi-structured interviews,two rounds of Delphi expert consultation and the analytic hierarchy process.Based on the drafted system,a questionnaire was formulated.The tests for validity and reliability were conducted on 290 patients selected by convenience sampling.Results The finalised ICU patient care difficulty index system was composed of 5 primary indices(the general condition of the patient,disease condition,nursing condition,social support,and organizational characteristics),13 secondary indices and 27 tertiary indices.The Kendall's coefficient of coordination W values were 0.380 and 0.498,respectively,indicating a statistically significant agreement(both P<0.001).The system demonstrated a robust reliability(Cronbach's α=0.896)and a good internal consistency.Validity was confirmed through a scale level-content validity index(S-CVI)of 0.94 and the item level-content validity indices(I-CVI)ranged from 0.87 to 1.00.Structural validity analysis,based on 8 extracted public factors,showed a cumulative variance contribution rate of 66.34%.Conclusion The ICU patient care difficulty index system shows a high reliability and validity,making it a valuable tool for accurately quantification of the difficulty in ICU patient care.This system provides a scientific basis for allocation of ICU nursing resource and performance distribution.

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.

Oropharyngeal squamous cell carcinoma(OPSCC)is a malignant tumor originating from the squamous epithelium of the oro-pharyngeal mucosa,accounting for more than 90％of oropharyngeal malignancies.In recent years,human papillomavirus(HPV)infec-tion has become one of the primary etiological factors of oropharyngeal squamous carcinoma.The incidence of HPV-associated oropharyn-geal squamous carcinoma has been rising annually,with a noticeable trend toward younger populations,posing a significant threat to hu-man health.Due to the distinct biological behavior and clinical characteristics of HPV-associated oropharyngeal squamous carcinoma com-pared to its non-HPV-related counterpart,the diagnostic and treatment strategies for oropharyngeal squamous carcinoma have undergone substantial changes.Prevention and screening for oropharyngeal squamous carcinoma are of critical importance.The diagnostic and treat-ment process involves multi-disciplinary collaboration,including oral and maxillofacial surgery,otolaryngology,head and neck surgery,oncology,radiology and pathology.Based on evidence from clinical practice,a comprehensive,integrated diagnostic and therapeutic ap-proach has been established,centered around the concept of"prevention,screening,diagnosis,treatment,and rehabilitation",covering the entire patient lifecycle and providing a valuable reference for clinical practice.

Objective To investigate the mechanism by which blue light irradiation-activated microglia mediate immune cell recruitment and exacerbate retinal damage,and to explore the role of microglial depletion in inhibiting immune infiltration and protecting the retina.Methods SPF-grade C57BL/6J mice were randomly divided into control group,blue light irradiation group,and PLX5622 pretreatment blue light irradiation group.A retinal injury model was established by continuous LED blue light irradiation for 2 days.In the PLX5622 pretreatment group,microglia were specifically depleted before blue light irradiation.After modeling,HE staining and OCT examination were used to examine retinal histomorphological changes;ERG examination was performed to evaluate retinal function;DHE staining and RT-qPCR were used to detect oxidative stress and inflammatory responses,and Iba1,CD68,CD11b immunofluorescence staining and flow cytometry were used to analyze microglial activation status and immune cell infiltration.Results After blue light irradiation,the retinal outer nuclear layer thickness was significantly reduced;ERG a-wave and b-wave amplitudes decreased;expression of oxidative stress-related genes Nrf2,Sod2,and HO-1 was upregulated;expression of inflammatory factors IL-1β,TNF-α,and ICAM-1 increased;the number of Iba1-positive microglia increased and migrated extensively to the outer nuclear layer;the proportion of CD68+cells and CD11b+immune cells was elevated;and activated microglia aggregated around blood vessels to mediate immune cell infiltration.After PLX5622 pretreatment to deplete microglia,immune cell infiltration was significantly reduced;inflammatory responses were alleviated;retinal structural damage was markedly improved,and visual function was protected.Conclusions Blue light irradiation activates microglia and promotes their migration to the injury area.Activated microglia mediate immune cell recruitment and infiltration,exacerbating retinal inflammatory damage.Microglial depletion can effectively inhibit immune infiltration,rescue retinal structure and function,and provide new therapeutic strategies for the prevention and treatment of blue light-related ocular diseases.