Objective To evaluate the association between baseline serum vitamin D levels and the occurrence， progression， and mortality risk of cardio-renal-metabolic disease （CRMD）， and to explore the modifying effect of population characteristics. Methods Based on a prospective cohort study of 377 861 participants free of CRMD at baseline from the UK Biobank， the Cox model and a multi-state model （MSM） were used to analyze the associations between serum vitamin D levels and the risk of first CRMD （FCRMD）， cardio-renal-metabolic multimorbidity （CRMM）， and death. In addition， restricted cubic spline and stratified analyses were conducted. Results A total of 64 804 FCRMD events and 15 725 CRMM events were observed. The Cox model showed that both insufficient and deficient serum vitamin D levels significantly increased the risk of FCRMD， CRMM， and death. The risk of CRMM was the highest in the serum vitamin D deficiency group （HR=1.29， 95%CI：1.24-1.35）. The MSM indicated that deficient serum vitamin D level increased the risk of progression from FCRMD to CRMM by 13% and the risk of death after CRMD by more than 21%， and its association was most significant on cardiovascular disease and type 2 diabetes pathways. Serum vitamin D concentration was associated with CRMD risk in a U-shaped pattern， with the lowest point approximately at 50 nmol/L. Stratified analysis indicated that the risk of occurrence and progression of CRMD was significantly higher in obese individuals and those with low socioeconomic status. Conclusion Low serum vitamin D levels were significantly associated with an increased risk of CRMD occurrence and progression， and the association was more pronounced in obese and low socioeconomic status populations. Maintaining an appropriate serum vitamin D level may help prevent the occurrence and progression of CRMD.

Objective To evaluate the vaccine effectiveness （VE） of trivalent inactivated influenza vaccine （IIV3） against laboratory-confirmed influenza among the elderly aged ≥60 years in Taizhou， Zhejiang Province. Methods Influenza-like illness （ILI） cases aged ≥60 years who had throat swab specimens collected at four influenza surveillance sentinel hospitals in Taizhou between Oct 2018 and Apr 2024 were included. A test-negative design （TND） case-control study was conducted， in which influenza-positive and influenza-negative cases were frequency matched at a 1∶1 ratio based on hospital， date of visit （±30 days） and age （60-69 years and ≥70 years）. A Logistic regression model was used to estimate the vaccine effectiveness （VE） of the IIV3. Results A total of 386 eligible participants were included after matching， with 193 cases in both the influenza-positive and influenza-negative groups. The vaccination coverage of IIV3 was 21.2% in the influenza-positive group and 36.8% in the influenza-negative group. The overall VE of IIV3 against laboratory-confirmed influenza among the elderly aged ≥60 years was 56.5% （95%CI：29.9%-73.3%）. The VE against influenza A and B was 48.4% （95%CI：11.9%-70.2%） and 79.3% （95%CI： 36.8%-93.9%）， respectively. The VE was 64.8% （95%CI： 27.3%-83.8%） among those aged 60-69 years and 49.8% （95%CI：1.5%-74.8%）. Among the elderly with and without chronic diseases， VE was 57.0% （95%CI：20.3%-77.3%） and 57.9% （95%CI：10.2%-80.9%）， respectively. Conclusion IIV3 provides moderate protection against influenza in medically attended elderly individuals aged ≥60 years.The findings further support the effectiveness of influenza vaccination in reducing the risk of influenza infection among the elderly.

Objective To develop and externally validate an improved extended prediction model for vaginal birth after cesarean section （VBAC）. Methods A total of 848 pregnant women who attempted a trial of labor after cesarean section （TOLAC） were retrospectively enrolled at Obstetrics and Gynecology Hospital， Fudan University from Jan 2016 to Mar 2024. The development dataset comprised 705 women， while the other 143 women constituted the external validation dataset. Variable selection was executed using the LASSO regression method. Model development was performed using multivariate Logistic regression techniques and was presented as a nomogram. Results The total VBAC rate was 82.0%. The base model included maternal age， interpregnancy interval， previous vaginal delivery， previous emergency cesarean section， birth weight of the newborn from the previous cesarean section. The AUC was 0.622 （95%CI：0.566-0.677）. For further development and external validation of the extended model （including spontaneous labor onset in the third trimester）， the AUCs were 0.737 （95%CI：0.697-0.790） and 0.657 （95%CI：0.535-0.780）， respectively. The calibration curves indicated a good accordance between predicted probabilities and observed incidences of VBAC. Internal validation performed by bootstrap resampling confirmed the model’s robust performance. An optimal predicted probability cut-off of 0.832 was identified by decision curve analysis and clinical considerations. Conclusion The extended model which added the variable of “spontaneous labor onset” for predicting the probability of achieving VBAC in the first trimester， exhibited relatively adequate performance. Women with an extended model-derived probability score of 0.832 or higher may consider TOLAC to improve the proportion and success rate of TOLAC.

Objective To investigate the role and underlying mechanism by which mouse dental pulp stem cells-derived exosome （DPSCs-exo） promote the differentiation of oligodendrocyte precursor cells （OPCs） into mature oligodendrocytes （OLs） via MSTRG.19716.1. Methods The copy number of MSTRG.19716.1 in DPSCs-exo and OPCs was determined by RT-qPCR. Mouse OPCs were pretreated with exosome inhibitor Dynasore （20 μmol/L） or pretransfected with siRNA-MSTRG.19716.1， followed by treatment with 10 and 100 μg/mL DPSCs-exo for 48 h. The expression of O4 （a biomarker of OL） and myelin basic protein （MBP） was detected by immunofluorescence assay. The relative expression levels of MSTRG.19716.1， miR-294-3p and oligodendrocyte transcription factor 2 （OLIG2） mRNA were measured by RT-qPCR. A luciferase reporter assay was performed to verify the binding of miR-294-3p to Olig2 mRNA and the regulatory effect of MSTRG.19716.1 on this interaction. Uptake of DPSC-exo was assessed by exosome tracing assay， and OLIG2 protein expression was determined by ELISA. Results MSTRG.19716.1 was significantly enriched in DPSCs-exo compared with that in OPCs. Treatment with DPSCs-exo significantly increased MBP expression and the proportion of O4-positive cells in OPCs， and this effect was markedly inhibited by Dynasore. Further studies showed that miR-294-3p could bind to Olig2 mRNA， whereas MSTRG.19716.1 suppressed this interaction. Uptake of DPSCs-exo significantly upregulated MSTRG.19716.1 levels and promoted OLIG2 protein expression in OPCs. These effects were markedly attenuated after transfection with siRNA-MSTRG.19716.1. Conclusion DPSCs-exo promote the differentiation of OPCs into OLs by delivering MSTRG.19716.1， which upregulates OLIG2 protein expression in OPCs.

Objective To evaluate the continuity of primary healthcare services among patients with diabetes， analyze the bidirectional associations with health outcomes and medical costs， and provide evidence for improving continuity of care in county-level healthcare institutions. Methods We included 4 104 patients diagnosed with diabetes in Yuhuan City， Zhejiang Province， who had at least three outpatient visits per year between 2021 and 2024. Data were obtained from residents’ health records， chronic disease follow-up records， and the county medical consortium information system. Service continuity indicators were constructed， including the usual provider of care （UPC） index， the primary healthcare index （PHCI）， and a binary variable， which was established to indicate whether the patient’s usual provider of care was a primary healthcare institution （primary healthcare institutions as usual provider of care， PHC-UPC）. The measurement periods were defined as T1 （2021-2022） and T2 （2023-2024）. Cross-lagged panel models were employed to examine the dynamic associations between primary healthcare continuity， hospitalization， glycemic control， and medical costs. Results Both PHCI and PHC-UPC at T1 were associated with a lower likelihood of hospitalization at T2 （γ=-0.047， P<0.05； γ=-0.042， P<0.05）， while poor glycemic control at T1 was associated with a lower PHCI at T2 （γ=-0.023， P<0.05）. For costs， higher PHCI and PHC-UPC at T1 were significantly associated with lower outpatient and inpatient expenditures at T2 （P<0.001）. Conclusion The continuity of primary healthcare services among patients with diabetes in Yuhuan City was generally at a relatively high level， which was associated with subsequent reductions in healthcare expenditures and a lower risk of hospitalization. Meanwhile， patients with suboptimal glycemic control demonstrated higher continuity of primary care utilization in the subsequent period.

Objective To evaluate the impact of the free medication delivery program in Deqing County， Zhejiang Province， on the utilization and medical costs of outpatient and inpatient of hypertension-related diseases， as well as control rate of hypertension. Methods Data on control rates of hypertension from 2014 to 2021， monthly averages of outpatient and inpatient visits and related costs for hypertension-related diseases from 2014 to 2021， and free medication delivery records from 2018 to 2021 in Deqing County were collected. χ² tests and interrupted time series analyses with multiple intervention points were carried out. Results Coverage of the free antihypertensive medication delivery program showed an increasing trend. By 2021， 20.91% of patients with hypertension had received free medications. Before program implementation （from Jan 2014 to Apr 2018）， outpatient visits and inpatient visits related to hypertension-associated diseases increased by an average of 411.47 visits and 0.81 visits per month， respectively. Total outpatient and inpatient expenditures increased by an average of CNY 58 410.57 and CNY 5 355.88 per month， respectively. The average outpatient expenditure per visit increased by CNY 0.44 per month， while no significant change was observed in average inpatient expenditure per visit. After program implementation （May 2018 to Dec 2019）， outpatient visits changed from an increasing trend to a decreasing trend， with an average monthly reduction of 182.36 visits. No statistically significant change was observed in the trend of total outpatient expenditures， whereas average outpatient expenditure per visit continued to increase， with an average monthly increase of CNY 0.79. Inpatient visits decreased by an average of 1.64 visits per month， total inpatient expenditures decreased by CNY 29 831.58 per month， and average inpatient expenditure per visit decreased by CNY 119.40 per month. Meanwhile， the hypertension control rate gradually improved， reaching 73.16% in 2021. Conclusion The free antihypertensive medication distribution program in Deqing County improved the control rate of hypertension， reduced inpatient service utilization and associated economic burden， and decreased outpatient visits， although the average cost per outpatient visit further increased.

Objective To retrospectively analyze the associated factors of postoperative fever and urosepsis after flexible ureteroscopy， and to preliminary establish a urosepsis prediction scoring system. Methods To analyze the clinical data of patients diagnosed with renal calculi and ureteral calculi who underwent one-stage ureteroscopic ureterolithotomy in Minhang Hospital， Fudan University from Dec 2022 to Dec 2023 in a retrospective cohort study， preoperative blood routine， urine routine， midcourse urine culture， C-reactive protein （CRP），procalcitonin （PCT） and unenhanced CT findings were analyzed. Logistic regression analysis was used to screen the risk factors of postoperative urosepsis， and nomogram was used to score the risk factors. Results Of the enrolled 571 patients in this study， 73 cases had systemic infection， and 19 cases had urosepsis. Univariate analysis showed that elevated blood leukocyte count， elevated urine leukocyte count， elevated CRP， elevated PCT， positive urine bacterial culture， thickening of renal pelvis， hydronephrosis， extrarenal exudation， and stone burden were associated with postoperative fever and urosepsis. In addition， positive urinary nitrite was associated with postoperative fever. Multivariate analysis showed that elevated blood leukocyte count （OR=2.62，P=0.01）， positive urinary bacteria culture （OR=5.21，P=0.04）， thickening of renal pelvis （OR=11.31，P<0.01） and extrarenal exudation （OR=9.53，P<0.01） were significantly associated with postoperative fever. Positive urine culture （OR=6.84， P=0.04）， thickening of renal pelvis （OR=5.92， P=0.02） and extrarenal exudation （OR=7.01，P=0.03） were significantly associated with postoperative urosepsis. Based on Logistic multivariable analysis， nomogram map could forecast the risk probability of systemic infection and urosepsis after endoscopic urological surgery in patients with lithiasis. The internal validation results showed that the predicted value of the calibration curve of the nomogram model was basically consistent with the actual value， and the AUCs of the training cohort and the test cohort were 0.86 （0.80-0.91） and 0.82 （0.74-0.91） respectively， indicating that the model had a positive net benefit. Conclusion Renal pelvic wall thickening， extrarenal exudation， and positive bacterial urine culture were three factors associated with urosepsis in patients with upper urinary tract calculi. A predictive scoring system for urosepsis was established and applied， and it may assist in decision-making regarding the surgical plan and timing for patients with upper urinary tract calculi.

Objective To investigate the correlation between impulse oscillometry （IOS） parameters and ventilatory and gas exchange functions in patients with interstitial lung disease （ILD）， and to evaluate the clinical application value of IOS in the assessment of pulmonary function in ILD. Methods This retrospective study enrolled 119 patients with ILD confirmed by a multidisciplinary team between Nov 2022 and Apr 2024.All patients completed conventional pulmonary function tests （including ventilatory and gas exchange functions） and IOS examinations. Patients were stratified into subgroups based on the percentage of predicted forced vital capacity （FVC%pred） for ventilatory function and the percentage of predicted diffusing capacity of the lung for carbon monoxide （DLCO%pred） for gas exchange function. Differences in IOS parameters among groups with varying degrees of functional impairment were compared， and the correlations between IOS parameters and FVC%pred as well as DLCO%pred were analyzed. Results Among the IOS parameters， total respiratory impedance （Z5， Z5%）， total airway resistance （R5， R5%）， peripheral airway resistance （R5-R20）， resonant frequency （Fres）， and reactance area （AX） all increased significantly with the severity of ventilatory impairment （all P<0.05）， while peripheral reactance （X5） became more negative （P<0.001）. Central airway resistance （R20） showed no significant difference in intergroup comparisons. Regarding gas exchange function， except for limited associations observed for X5 and AX with DLCO%pred （P<0.05）， the remaining IOS parameters showed no significant differences across the DLCO%pred subgroups. Correlation analysis showed that all IOS parameters were significantly correlated with FVC%pred （all P<0.05）， with AX showing the strongest correlation （r_s=-0.462）. In contrast， their correlations with DLCO%pred were generally weaker （|r_s|<0.4）. Specifically， Z5% （r_s=-0.242）， R5% （r_s=-0.189）， R5-R20 （r_s=-0.254）， X5 （r_s=0.313）， Fres （r_s=-0.263）， and AX （r_s=-0.358） showed statistically significant but weak correlations with DLCO%pred （all P<0.05）. Analysis of clinical symptoms and signs showed that ILD patients with clinical symptoms had significantly higher R5-R20 than the asymptomatic group （P=0.013）， and more negative peripheral reactance （X5） values （P=0.035）. Patients with positive physical signs had significantly more negative X5 values than those without physical signs （P=0.010）. ROC curve analysis showed that AX and R5-R20 had moderate discriminative efficacy for identifying abnormal ventilatory function， with the AUC of 0.7456 and 0.7265， respectively. Conclusion IOS parameters are closely associated with the degree of ventilatory impairment in ILD patients， and are sensitive in reflecting changes in peripheral airway resistance and lung elasticity. However， their value in assessing gas exchange function is limited. IOS can serve as an effective auxiliary tool for evaluating ventilatory function in ILD patients， especially for those unable to cooperate with conventional pulmonary function tests. A comprehensive assessment should be performed by combining IOS with DLCO and other conventional indicators.

Objective To analyze the discussion topics， sentiment tendencies， and temporal trends of public discourse on smoke-free environment construction and smoke-free legislation in China based on data of Weibo platform from 2011 to 2021， and to provide empirical evidence for optimizing the formulation and implementation of smoke-free legislation. Methods Posts related to smoke-free environments published on the Weibo platform from Jan 2011 to Dec 2021 were collected using Python 3.11.3. Comments concerning smoke-free legislation were subsequently identified and extracted. Topic modeling and sentiment analysis were conducted separately for posts and comments， and the temporal trends of comments related to smoke-free legislation were characterized. Results A total of 102 733 valid Weibo posts and 455 016 comments related to smoke-free legislation were included. Among the posts on smoke-free environments， the most frequently discussed topics were the “smoker image” （n=988） and “smoking in indoor public places” （n=775）. Sentiment analysis of these topics showed that more than 90% of the posts conveyed negative attitudes. Among comments related to smoke-free legislation， the topic “strongly support the smoke-free policy” （n=848） was predominant. Overall， positive sentiment outweighed negative sentiment， with negative comments primarily expressing concerns regarding policy implementation. Temporal trend analysis showed that the volume of related comments increased gradually from 2016 to 2019， peaked around 2019， and then declined. Conclusion Smoke-free environments and tobacco control legislation remained subjects of sustained public attention on Weibo platform. Public discussion mainly focused on smoking behavior in specific settings， social cognition of smoking， and smoke-free regulations. Overall， the public generally holds negative attitudes toward smoking and broadly support smoke-free legislation， alongside calls for stronger policy enforcement. There is already a degree of consensus on smoke-free legislation at the level of public opinion.

Objective To compare gastric mucosa of corpus and antrum among obese， overweight and normal-weight individuals， to elucidate pathophysiological mechanisms for mucosal metabolic and immune dysregulation. Methods A retrospective cohort of gastric biopsies （2022-2025， Huadong Hospital， Fudan University） was classified by BMI： surgical obesity （Obese-S， n=518）， obesity found by gastroscope （Obese-E， n=35）， overweight （Overweight-E， n=114） and normal weight （Control-E， n=172）. Hematoxylin-eosin and immunohistochemical staining were applied to assess chronic inflammation， activity， atrophy， intestinal metaplasia （IM） and Helicobacter pylori （Hp） status. Results Hp positivity was significantly higher in Obese-S （25.1%）， Obese-E （34.3%） and Overweight-E （25.4%） groups compared with Control-E （14.0%） （all P<0.01）. Chronic inflammation in the gastric corpus was observed in 35.7%， 40.0%， 29.8%， and 13.9% of cases in the 4 groups （all P<0.05， vs. Control-E）， and activity occurred in 26.3%， 45.7%， 35.1%， and 20.4% of the cases （all P<0.05， vs. Control-E）. Hp positivity strongly correlated with both chronic and active inflammation （P<0.001）. Conversely， atrophy in gastric corpus showed the opposite trend： 0.4%， 11.4% and 10.5% respectively in the high BMI group， significantly lower than that in the Control-E group （16.3%） （all P<0.05）. IM accounted for 75.0%-100% of atrophic lesions. In gastric autrum， mucosal atrophy and IM were also less prevalent in the Obese-E and Overweight-E groups （all P<0.05， vs. Control-E）. Both atrophy and IM showed no correlation with Hp infection. Conclusion Higher BMI is associated with increased Hp infection and gastric corpus inflammation or active lesions， while IM and atrophy in gastric corpus declines， suggesting Hp-driven inflammation dominates gastric mucosa in obese individuals.

Objective To build an open-source behavioral science hardware and software system Bonsai Arduino Network Open Ephys （BANO） based on Bonsai and Arduino for mice observational fear learning research. Methods The system used the graphical programming interface provided by Bonsai software to design the behavioral experiment logic control flow and connected to an Arduino microcontroller to achieve real-time data interaction. The Arduino board controlled the output of sound stimuli and transistor-transistor logic （TTL） signals， and synchronized the TTL data to the Open Ephys electrophysiological recording system for synchronizing behavioral and neuroelectrophysiological data. Results This open-source platform could realize the programming of complex sound stimuli， trial randomization， video recording and auxiliary equipment output control， and could precise communicate and synchronize events with other external devices， providing high-quality information flow for subsequent neuroelectrophysiological signal and behavioral analysis. Conclusion This system provides a low-cost， flexible， and highly scalable behavioral training solution， which can promote the development of new tools and methods in open-source neuroscience behavioral science.

Objective To construct a prokaryotic expression vector of the anti-CRISPR protein AcrIE10， and to determine the crystal structure of AcrIE10 protein by X-ray diffraction technology. Methods With the genomic DNA of Klebsiella pneumoniae as the template， the acrIE10 gene was inserted into the pET28a-SUMO expression vector to construct the recombinant plasmid pET28a-SUMO-AcrIE10， which was then transformed into the competent cell BL21 （DE3）. We adjusted the environmental temperature during the protein purification process to explore the optimal purification conditions for the anti-CRISPR protein （AcrIE10）. Using Ni-NTA affinity chromatography and gel filtration chromatography， a pure and high-concentration protein solution was obtained. Then we cultivated and screened crystals， and collected protein crystal diffraction data at Shanghai Synchrotron Radiation Facility beamline station. Results The recombinant plasmid pET28a-SUMO-AcrIE10 was constructed and transformed into competent BL21 （DE3） cells. After removing the 6×His and SUMO tag proteins， the optimal purification temperature was 20 ℃. After purification by Ni-NTA affinity chromatography and gel filtration chromatography， the protein solution concentration was 18 g/L. Appropriate crystals were grown under the conditions of PEG 3000 （w/v=10%）， imidazole （0.1 mol/L）， hydrochloric acid （pH=8.0） and lithium sulfate （0.2 mol/L）. The crystal diffraction resolution was 2.39 Å. The crystal structure of AcrIE10 apo was successfully resolved. The structure analysis showed that the AcrIE10 protein assembled in a homodimeric form. Its overall folding consisted of a short β-sheet （β1） and six α-helices （α1-α6）. β1 and α1， α2 formed the N-terminal domain of the AcrIE10 protein， which was a typical ribbon-helix-helix （RHH） domain. Conclusion The AcrIE10 protein of Klebsiella pneumoniae can be highly expressed in the prokaryotic expression system. By removing the 6×His and SUMO tags and using a purification temperature of 20 ℃， the AcrIE10 protein can be obtained more efficiently. The AcrIE10 protein has a typical RHH domain， suggesting that it might be a bifunctional protein.

Objective To develop prognostic prediction models for treatment regimens in advanced primary hepatocellular carcinoma （HCC） using machine learning （ML）， identify key prognostic indicators， and evaluate the clinical decision-making utility of each model. Methods A retrospective analysis was conducted on 120 patients with advanced HCC admitted to Yixing People’s Hospital from Jun 2010 to Jun 2024. The overall survival （OS） of patients receiving chemotherapy alone， targeted therapy combined with immunotherapy， and triple therapy of targeted therapy plus radiotherapy and immunotherapy was compared. OS was evaluated using Kaplan-Meier curves. Cox proportional hazards models were used to determine key prognostic factors， including serological indicators and tumor markers. Five models， namely Logistic regression （LR）， support vector machine （SVM）， random forest （RF）， extreme gradient boosting （XGBoost）， and the light gradient boosting machine （LightGBM） were employed to predict prognosis under different treatment modalities， and their performance was evaluated using leave-one-out cross-validation （LOOCV）. The shapley additive explanation （SHAP） value analysis was used to assess the contribution of model features. Results Combined therapy significantly prolonged OS （all P<0.000 1）. Multivariate Cox regression revealed that alpha-fetoprotein （AFP） and β2-microglobulin （β2-MG） were associated with a favorable prognosis， while C-reactive protein （CRP） and platelet-to-lymphocyte ratio （PLR） were poor prognostic factors. In the binary classification task， the RF and XGBoost models outperformed the others. SHAP analysis further confirmed that CRP was the most significant factor contributing to model predictions. Conclusion The triple therapy significantly improves the prognosis of advanced HCC. ML models can accurately predict survival outcomes under different treatment modalities and identify prognostic markers， providing data support for individualized treatment decisions.

Aromatase inhibitor-associated musculoskeletal symptoms （AIMSS） have become an important issue affecting quality of life and treatment adherence in patients receiving endocrine therapy for breast cancer. A systematic literature search was conducted in Chinese and international databases for studies on AIMSS management strategies and their implementation and outcomes from database inception to Feb 22， 2025. A total of 15 studies were included. Existing AIMSS management strategies mainly involved exercise interventions， technology-assisted support， and multidisciplinary/comprehensive interventions. Overall， these strategies were beneficial for short-term pain relief and functional improvement. However， limitations remained in long-term adherence and sustained implementation. The main implementation barriers included limited accessibility of health resources， inadequate adaptation to information technology， and insufficient follow-up support mechanisms. Major facilitators included individualized adaptation of interventions， nurse-led multidisciplinary collaboration， technology-enabled support， and the integration of nursing and patient education into information-based symptom management pathways. Future efforts should be guided by implementation science to build a closed loop between evidence and practice， adopt stratified management according to symptom severity， integrate digital technologies， and optimize multidisciplinary collaboration and resource allocation so as to promote the sustainable implementation of AIMSS management in patients with breast cancer receiving endocrine therapy.

Infectious diseases cause millions of deaths annually， and the emergence of novel pathogens and antimicrobial resistance has further increased the diagnostic and therapeutic burden. Conventional approaches have clear limitations in terms of efficiency and sensitivity； therefore， innovative technologies are urgently needed to achieve rapid and accurate diagnosis and timely treatment of infectious diseases. This review summarizes research progress on the application of artificial intelligence in infectious disease diagnostics and therapeutics， including pathogen detection， medical imaging analysis， antimicrobial resistance testing， epidemic trend prediction and surveillance， and portable rapid on-site diagnostics， providing insights for both basic research and clinical practice in infectious disease management.

Male infertility accounts for approximately 5% of reproductive health problems among men of reproductive age. Chromosomal translocations are closely associated with male infertility. The breakpoint of the translocation may disrupt or dysregulate important genes involved in spermatogenesis. In order to investigate the association between chromosome 2p21 translocation and male infertility， we performed detailed medical history review， semen analysis， cytogenetic analysis， and a review of related gene function in three carriers of a 2p21 translocation. Our findings suggested that this translocation might affect sperm count， motility and function by disrupting genes crucial for spermatogenesis， namely EPCAM， MSH2 and EPAS1， thereby leading to male infertility. Therefore， it is important to consider the 2p21 translocation in genetic counseling and treatment of male infertility， and further research is needed to elucidate its specific impact on the underlying mechanisms of spermatogenesis.

Longitudinal population studies often involve repeated measurements of symptom scores， biomarkers， health behaviors， or functional status in the same individuals. Although reporting a single overall mean trajectory can describe average change at the population level， it fails to capture substantive differences in patterns of change across individuals. For example， some individuals remain stable over time， whereas others follow trajectories characterized by early decline， rapid deterioration， or persistently low levels. Group-based trajectory modeling （GBTM） is a semiparametric approach， based on finite mixture models， that uses a finite set of latent trajectories to approximate longitudinal patterns in different subgroups within a population. This article presents the methodological framework of classical GBTM through a complete analytical workflow， covering （1） its underlying principles， model structure， and outcome distributions； （2） key distinctions from related trajectory models； （3） model building， model selection， and assessment of classification quality； and （4） analysis of factors associated with trajectory group membership，as well as an overview of commonly used R tools. A case study using longitudinal mini-mental state examination （MMSE） data from older adults in the PAQUID cohort illustrates a standard four-step workflow for applying GBTM： data preparation and model specification； comparison of candidate models； identification of trajectory groups and assessment of classification quality； and exploratory analysis of associated factors. The example demonstrates how age-related changes in cognitive function among older adults can be summarized by four trajectories： relatively preserved， accelerating decline， lower-level slow decline， and early rapid decline. The value of GBTM lies not in claiming to discover naturally occurring disease subtypes， but in proposing and presenting interpretable subgroup trajectory patterns that clarify population heterogeneity and generate testable hypotheses for subsequent stratified research on etiology， prediction， and intervention.