Objective: To investigate the association between screen time (ST) during leisure time and anxiety-depression symptoms among middle school students, so as to provide a basis for formulating relevant intervention measures. Methods: From November to December 2023, a stratified cluster random sampling method was used to select 2 542 students from junior and senior high school in Taiyuan City. A self designed questionnaire, the Generalized Anxiety Disorder Scale (GAD-7), and the Patient Health Questionnaire (PHQ-9) were used to investigate ST and anxiety/depression symptoms among middle school students. The Logistic regression model was used to explore the association of ST with symptoms of anxiety and depression, as well as with anxiety and depression comorbiditles (CAD). Results: The detection rates of anxiety symptoms, depression symptoms, and CAD were 13.69%, 15.77%, and 10.11%, respectively. The median ST was 2.00 h/d [interquartile range ( IQR =2.38) for weekly averages], with 0.33 h/d ( IQR =1.67) on work days and 5.00 h/d ( IQR=5.50) on rest days. Logistic regression analysis indicated that the total ST of mobile phones during rest days ( OR =1.07, 1.10, 1.11) and the averages ST of mobile phones over a week ( OR = 1.20 , 1.22, 1.29), as well as the total ST of all screen types during rest days ( OR =1.04, 1.04, 1.05) and the averages ST of all screen types over a week ( OR =1.08, 1.09, 1.21) were positively correlated with anxiety symptoms, depression symptoms, and CAD (all P <0.01). Conclusions Among middle school students in Taiyuan City, screen time is positively correlated with symptoms of anxiety or depression and the comorbidity of anxiety and depression, especially smartphone screen time and weekend screen use. Therefore, measures should be implemented to reduce unnecessary screen time among middle school students, especially the use of mobile phones, in order to mitigate the occurrence of anxiety and depression.

OBJECTIVE To analyze the risk factors for multidrug-resistant organism （MDRO） infection in patients with prolonged invasive mechanical ventilation （IMV） complicated by ventilator-associated pneumonia （VAP） in the intensive care unit （ICU）， thus providing a reference for improving the clinical effect of VAP treatment in this region. METHODS A retrospective analysis was performed on the clinical data of patients who were admitted to the ICU in Shexian Branch of the Second Affiliated Hospital of Zhejiang University School of Medicine （hereinafter referred to as “our hospital”） from October 2022 to February 2025， received prolonged IMV， and developed VAP. The distribution and drug resistance of pathogens were statistically analyzed. Patients were divided into the MDRO group and the non-MDRO group according to whether an MDRO infection occurred. Univariate analysis and multivariate Logistic regression analysis were used to screen independent risk factors for MDRO infection. RESULTS A total of 281 pathogenic strains were cultured from 97 patients， including 262 Gram-negative bacteria （93.24%）， 9 Gram-positive bacteria （3.20%）， and 10 fungi （3.56%）. The main Gram-negative bacteria were Pseudomonas aeruginosa， Klebsiella pneumoniae subspecies pneumoniae， and Acinetobacter baumannii. The former two showed high resistance rates （all≥25%） to common antibiotics such as imipenem， while A. mail：64375689@qq.com baumannii demonstrated high resistance to most antimicrobial agents. The main Gram-positive bacteria were Staphylococcus aureus subspecies aureus and S. haemolyticus， which were resistant to multiple antibiotics such as clindamycin （resistance rates all＞30%）. Among 281 pathogenic strains， 121 were MDRO， 62 were resistant to carbapenems， and 33 produced extended-spectrum β-lactamases. The serum albumin＜28 g/L， ICU stay≥14 days， and use of benzodiazepines were independent risk factors for MDRO infection in patients with prolonged IMV and VAP in our hospital’s ICU （odds ratios were 3.289， 2.991 and 2.680， 95% confidence intervals were 1.183-9.144， 1.021-8.765， and 1.012- 7.094， respectively， P＜0.05）. CONCLUSIONS Pathogens infecting patients with prolonged IMV and VAP in the ICU are mainly Gram-negative bacteria， with P. aeruginosa， K. pneumoniae subspecies pneumoniae and A. baumannii， accounting for a high proportion， and the drug resistance situation is severe. Serum albumin＜28 g/L， ICU stay≥14 days， and use of benzodiazepines are independent risk factors for MDRO infection in such patients.

OBJECTIVE To explore the effects of meropenem exposure and degradation levels on clinical efficacy in patients with purulent meningitis （PM）. METHODS A total of 131 PM patients treated with meropenem at the Affiliated Suzhou Hospital of Nanjing Medical University from January 2022 to June 2025 were prospectively included. Relevant data were collected and divided into a cured group （91 cases） and a non-cured group （40 cases） based on the efficacy. High-performance liquid chromatography-tandem mass spectrometry was used to determine the concentration of meropenem and its open-loop metabolites. Risk factors that affect efficacy were screened， and their predictive power and correlation were evaluated by univariate analysis， and multivariate Logistic regression analysis， receiver operating characteristic （ROC） curves， and correlation analysis. RESULTS Univariate analysis showed that serum creatinine， creatinine clearance rate， minimum inhibitory concentration of meropenem ≥16 μg/mL， cerebrospinal fluid red blood cell count， cerebrospinal fluid white blood cell count， cerebrospinal fluid glucose content， blood trough concentration， blood open-loop metabolite concentration/trough concentration ratio， and intrathecal injection were all correlated with efficacy （P＜0.05）. The results of multiple Logistic regression analysis showed that serum creatinine blood open-loop metabolite concentration/trough concentration ratio， intrathecal injection， and cerebrospinal fluid glucose content were influencing factors for suboptimal anti-infective ltt efficacy （P＜0.05）. ROC curve analysis showed that when the blood open-loop metabolite concentration/trough concentration ratio was greater than 2.854 （AUC＝0.647）， serum creatinine was less than 59.5 μmol/L （AUC＝0.647）， and cerebrospinal fluid glucose content was less than 3.37 mmol/L （AUC＝0.709）， the risk of treatment failure significantly increased （P＜0.05）. Correlation analysis showed that the blood trough concentration of meropenem was positively correlated with the concentration of its open-loop metabolites （R 2＝0.134 5， P＜0.000 1）. CONCLUSIONS Insufficient exposure level and rapid degradation of meropenem are key mechanisms affecting the anti-infective efficacy of PM. Elevated blood open-loop metabolite concentration/ trough concentration ratio， low serum creatinine level， lack of intrathecal injection， and low cerebrospinal fluid glucose content are independent risk factors for poor efficacy.

Twelve derivatives of asiatic acid were synthesized through acylation, alkylation, oxidative dehydrogenation and other reactions using asiatic acid from usoxane-type pentacyclic triterpenoids as the parent compound. Their structures were confirmed by 1H NMR and 13C NMR, and determined to be novel compounds never reported in literature. Through the MTT method, high-expression human cancer cells (A549 and SGC-7901) were selected for a preliminary in vitro anti-tumor activity study on these compounds. Among them, the IC50 of compound I1 were 11.39 and 9.08 μmol/L respectively, and those of compound I2 were 12.64 and 9.15 μmol/L respectively, which were close to those of sorafenib, a common drug for clinical use. The experimental results show that the synthesized asiatic acid derivatives have certain anti-proliferative effects on the two types of human cancer cells, A549 and SGC-7901, significantly higher than those of asiatic acid. Compounds I1 and I2 show quite strong anti-proliferative effects on human cancer cells A549 and SGC-7901.

Objective:To investigate the effects of wza gene deletion in Klebsiella pneumoniae on capsule formation ability and bacteriophage sensitivity. Methods:The wza deletion mutant strain was constructed through a temperature-sensitive plasmid-mediated homologous recombination. The growth curves of W14 and Δ wza were detected by measuring the optical density OD 600. In order to analyze the effect of gene wza on bacterial capsule formation, wild-type strain W14 and Δ wza mutant strain were detected by transmission electron microscope, and their capsule contents were measured by quantifying the uronic acid contents. The plaque assay was used to detect bacterial sensitivity to bacteriophage in wild-type strain W14 and Δ wza mutant strain. The t test was used to compare whether there were differences in the contents of uronic acid in the capsules of wild-type strain W14 and Δ wza mutant strain. Results:The PCR results revealed that the Δ wza mutant strain was successfully constructed. Compared with wild-type strain W14, the growth curves of Δ wza on the solid plates demonstrated a slightly slower growth. However, no difference in growth was observed among wild-type strain W14 and Δ wza mutant strains in LB broth. The transmission electron microscope results showed that wza gene deletion resulted in the loss of capsule in bacteria. The uronic acid content assay suggested that the capsule content was significantly decreased in Δ wza mutant strain (45.963±2.795) μg/ml compared with wild-type strain W14 (138.800±5.201) μg/ml. There was a statistical difference between the two groups ( t=27.233, P<0.001). The plaque assay indicated that bacteria lost its sensitivity to bacteriophage when gene wza was deleted. Conclusion:Deletion of the wza gene impairs bacterial capsule formation ability and can affect bacterial sensitivity to bacteriophage phiW14.

Objective:To express and purify the phage depolymerase from hypervirulent Klebsiella pneumoniae (hv Kp) serotype K1 and validate its function. Methods:Phage that infected serotype K1-type hv Kp was isolated from hospital sewage. The biology and morphology of the phage were determined by plaque assay and transmission electron microscopy. The whole genome of the phage was sequenced by the Illumina HiSeq 2500 platform. The presence of depolymerase was determined by observing the plaque halo. Bioinformatic analysis and prokaryotic protein expression system were further used to predict and identify phage depolymerase. The depolymerase gene fragment was obtained by PCR and cloned into the pET28a expression vector, and the expression and purification of the depolymerase were completed in strain BL21. The depolymerase activities on the capsular polysaccharide of serotype K1-type hv Kp clinical isolates were detected by plaque assay and low-speed centrifugation assay. Results:A lytic phage (phiA2) that infected serotype K1-type hv Kp clinical isolate was isolated from hospital sewage. It was typical of the Caudovirales order and Autographiviridae family, and its whole genome was 43 526 bp in length and contained 51 coding domain sequences. The phage phiA2-derived depolymerase phiA2-dep was predicted, expressed and purified. The plaque assay and low-speed centrifugation assay indicated that the depolymerase phiA2-dep had good lytic activity on the capsular polysaccharide of serotype K1-type hv Kp clinical isolates. Conclusion:Depolymerase phiA2-dep can specifically degrade the capsular polysaccharide of serotype K1-type hv Kp, which has potential application value in treating bacterial infection.

Objective:To investigate the effects of wza gene deletion in Klebsiella pneumoniae on capsule formation ability and bacteriophage sensitivity. Methods:The wza deletion mutant strain was constructed through a temperature-sensitive plasmid-mediated homologous recombination. The growth curves of W14 and Δ wza were detected by measuring the optical density OD 600. In order to analyze the effect of gene wza on bacterial capsule formation, wild-type strain W14 and Δ wza mutant strain were detected by transmission electron microscope, and their capsule contents were measured by quantifying the uronic acid contents. The plaque assay was used to detect bacterial sensitivity to bacteriophage in wild-type strain W14 and Δ wza mutant strain. The t test was used to compare whether there were differences in the contents of uronic acid in the capsules of wild-type strain W14 and Δ wza mutant strain. Results:The PCR results revealed that the Δ wza mutant strain was successfully constructed. Compared with wild-type strain W14, the growth curves of Δ wza on the solid plates demonstrated a slightly slower growth. However, no difference in growth was observed among wild-type strain W14 and Δ wza mutant strains in LB broth. The transmission electron microscope results showed that wza gene deletion resulted in the loss of capsule in bacteria. The uronic acid content assay suggested that the capsule content was significantly decreased in Δ wza mutant strain (45.963±2.795) μg/ml compared with wild-type strain W14 (138.800±5.201) μg/ml. There was a statistical difference between the two groups ( t=27.233, P<0.001). The plaque assay indicated that bacteria lost its sensitivity to bacteriophage when gene wza was deleted. Conclusion:Deletion of the wza gene impairs bacterial capsule formation ability and can affect bacterial sensitivity to bacteriophage phiW14.

Objective:To express and purify the phage depolymerase from hypervirulent Klebsiella pneumoniae (hv Kp) serotype K1 and validate its function. Methods:Phage that infected serotype K1-type hv Kp was isolated from hospital sewage. The biology and morphology of the phage were determined by plaque assay and transmission electron microscopy. The whole genome of the phage was sequenced by the Illumina HiSeq 2500 platform. The presence of depolymerase was determined by observing the plaque halo. Bioinformatic analysis and prokaryotic protein expression system were further used to predict and identify phage depolymerase. The depolymerase gene fragment was obtained by PCR and cloned into the pET28a expression vector, and the expression and purification of the depolymerase were completed in strain BL21. The depolymerase activities on the capsular polysaccharide of serotype K1-type hv Kp clinical isolates were detected by plaque assay and low-speed centrifugation assay. Results:A lytic phage (phiA2) that infected serotype K1-type hv Kp clinical isolate was isolated from hospital sewage. It was typical of the Caudovirales order and Autographiviridae family, and its whole genome was 43 526 bp in length and contained 51 coding domain sequences. The phage phiA2-derived depolymerase phiA2-dep was predicted, expressed and purified. The plaque assay and low-speed centrifugation assay indicated that the depolymerase phiA2-dep had good lytic activity on the capsular polysaccharide of serotype K1-type hv Kp clinical isolates. Conclusion:Depolymerase phiA2-dep can specifically degrade the capsular polysaccharide of serotype K1-type hv Kp, which has potential application value in treating bacterial infection.

Intravascular large B-cell lymphoma(IVLBCL)is an aggressive extranodal large B-cell lymphoma,cocurrence in the same organ with other malignancies is very rare,especially in the lung.Here,we report a rare case of lung adenocarcinoma with IVLBCL.The patient was admitted to the hospital due to diarrhea associated with fever and cough.A computed tomography(CT)scan of the chest showed an irregular patchy high-density shadow in the upper lobe of the right lung with ground-glass opacity at the margin.After admission,the patient was given anti-infection treatment,but still had inter-mittent low fever(up to 37.5 oC).The pathological diagnosis of percutaneous lung biopsy(PLB)was lepidic-predominant ad-enocarcinoma with local infiltration,which was proved to be invasive nonmucinous adenocarcinoma of the lung with IVLBCL after surgery.This paper analyzed the clinicopathological characteristics and reviewed the relevant literature to improve the knowledge of clinicians and pathologists and avoid missed diagnosis or misdiagnosis.

An important issue facing university education is the adaptation and transformation of freshmen.In order to guide students to adapt to the needs of research-based learning,Jilin University has opened a freshman seminar for all first-year undergraduate students,emphasizing the cultivation of students'thinking patterns and learning abilities.For medical students,it is necessary to ap-ply the learned medical knowledge to clinical problem analysis.Therefore,it is particularly important to cultivate students'integrated thinking from basic to clinical at the beginning of enrollment.In recent years,organ system integration has gradually been carried out in medical schools both domestically and internationally.In the course of integrating the immune system and diseases,the morphology of the immune system is relatively abstract and difficult to observe.In the early stages of enrollment,students still lack the thinking of organ system integration,and the initial stage of immune system integration courses is difficult to carry out.Therefore,we aimed to guide students towards adaptability and academic transformation through freshman seminars,explored the integration of the immune system's organ system as a pathway,and used the BOPPPS teaching model as a means for preliminary exploration.In the freshman seminar,the main focus is on the"morphology and structure-mechanism and function-disease-diagnosis-treatment"of the immune sys-tem,helping students establish a learning mindset that integrates disease diagnosis and treatment based on basic medical courses such as immunology and anatomy.Using BOPPPS to reform the"teaching"of teachers,establishing a student-centered teaching model from six aspects:bridge,objective,pre-assessment,participatory learning,post-assessment and summary,can better guide students to actively think and participate in the entire learning process,focus on the construction of students'fragmented knowledge thinking mode,internalize medical humanities literacy,and improve the quality of medical talent cultivation in colleges and universities.