1.Predicting intraoperative blood transfusion risk in hip fracture patients using explainable machine learning models
Fengting LU ; Xiaoming LI ; Dekui LI ; Xianyuan XIE ; Jiazhong WANG ; Qing YU ; Gan HUANG ; Jun SHEN
Chinese Journal of Blood Transfusion 2026;39(2):196-202
Objective: To investigate the factors influencing intraoperative blood transfusion in patients with hip fractures and to develop a machine learning (ML) model for predicting this risk. Methods: A total of 424 patients with hip fractures who underwent surgical treatment between November 2022 and March 2025 in our hospital were selected. Key feature variables of intraoperative blood transfusion risk were identified using the Boruta algorithm. Four different ML algorithms—support vector machine (SVM), linear discriminant analysis (LDA), mixed discriminant analysis (MDA), and extreme gradient boosting (XGBoost)—were used to develop predictive models for intraoperative blood transfusion risk. The predictive performance of the four ML models were evaluated using accuracy, precision, receiver operating characteristic (ROC) curves, precision-recall curves (PRC), precision-recall gain curves (PRGC), and F1 scores. Shapley additive interpretation (SHAP) was used to interpret the final model. Results: Among the 424 patients, 77(18.2%) received intraoperative blood transfusion. The Boruta algorithm identified albumin (ALB), activated partial thromboplastin time (APTT), types of anesthesia, types of fracture, and hemoglobin (Hb) as key feature variables for predicting intraoperative blood transfusion risk. In model evaluation, the SVM model outperforms the other three models across multiple metrics, including the area under the receiver operating characteristic curve (AUC), recall, recall gain, accuracy, precision, F1 score, and the area under the precision-recall curve (PRC-AUC). The SVM model, interpreted and visualized based on SHAP values, effectively predicted intraoperative blood transfusion risk in patients with hip fracture. A visual online application was developed based on the SVM model (https://pbo-nomogram.shinyapps.io/blood/). Conclusion: Preoperative low ALB and Hb levels, prolonged APTT, general anesthesia, and intertrochanteric fractures are risk factors for intraoperative blood transfusion in hip fracture patients. The risk prediction model for intraoperative blood transfusion constructed based on the SVM algorithm has optimal performance, which provides new ideas and methods for the clinical early identification of hip fracture patients with high transfusion risk and the implementation of targeted interventions.
2.Innovative Development and Cutting-edge Applications of Split Intein Technology
Jin-Qiu GAN ; Xiang-Yu DENG ; Xin-Yan WANG ; Jia-Bin LI
Progress in Biochemistry and Biophysics 2026;53(6):1520-1540
Inteins are unique protein insertion sequences capable of self-excision, enabling the covalent ligation of flanking extein peptides via amide bond formation. This process proceeds spontaneously without requiring external enzymes, cofactors, or chemical reagents, granting inteins exceptional biocompatibility and traceless performance in protein engineering applications. Split inteins represent a specialized and versatile subclass whose splicing domains are encoded by two separate gene fragments rather than a single continuous open reading frame. These fragments, known as the N-terminal (IntN) and C-terminal (IntC) split inteins, associate through non-covalent interactions including hydrophobic forces, hydrogen bonds, and van der Waals forces to assemble into an active three-dimensional structure, which then drives efficient extein ligation and enables protein trans-splicing. Protein trans-splicing mediated by split inteins has become a cornerstone for traceless protein ligation owing to its high specificity and irreversibility, fundamentally reshaping strategies for protein modification, assembly, and functional regulation. Compared with traditional chemical ligation methods, split intein systems require no complex chemical derivatization of peptide fragments and can operate efficiently at micromolar concentrations under physiological conditions, thus avoiding structural and functional damage caused by organic reagents. In contrast to enzymatic ligation tools such as sortase, split inteins eliminate the need for additional enzymes or cofactors, simplifying reaction systems, reducing costs, and minimizing non-specific side products. These distinctive advantages render split inteins highly promising for applications in chemical biology, synthetic biology, and biopharmaceutical development. In recent years, deepened mechanistic understanding has established structure-guided rational design as the primary approach to overcoming key limitations of split inteins, including intrinsic aggregation propensity, strict extein sequence dependence, and limited splicing efficiency. Bioinformatic tools have been used to identify aggregation-prone regions in the IntN fragment, and site-directed mutagenesis of hydrophobic residues, relocation of split sites, or removal of misfolding-prone sequences has substantially reduced in vitro aggregation and improved soluble expression and assembly activity. Rational engineering of catalytic residues and adjacent flexible loops has relaxed strict amino acid preferences at extein junctions, enhancing sequence tolerance and reducing the risk of functional impairment in target proteins. Consensus design based on multiple sequence alignments has yielded ultra-fast splicing variants such as Cfa DnaE and Cat-TerL, which exhibit significantly accelerated kinetics and improved tolerance to denaturing conditions. Meanwhile, advances in structural biology have further clarified the conformational dynamics and catalytic mechanisms of splicing, supporting the precise design of high-performance intein modules. On this basis, electrostatic interaction tuning and metagenomic screening have yielded multiple mutually orthogonal split intein pairs, enabling selective multi-fragment protein ligation and providing new routes for the efficient synthesis of large multi-domain functional proteins. With these engineered split inteins offering continuously improved performance and expanded applicability, protein trans-splicing has been widely applied in numerous cutting-edge areas of protein research and biomedicine. In gene delivery, split intein-based systems overcome the packaging limit of adeno-associated viral vectors, enabling the accurate reconstitution of large therapeutic proteins and base editors in target cells, thereby enhancing the efficacy and scope of gene therapy for genetic diseases. In internal protein sequence editing, split inteins mediate precise sequence replacement and modification in flexible regions or loops of target proteins, without the need for complex multi-step ligation and protein refolding involved in traditional protein semisynthesis. In protein-protein interaction studies, intein-mediated splicing covalently captures transient and weak intracellular complexes, enabling sensitive, high-throughput interaction detection and drug screening. In synthetic biology, conditionally controllable splicing systems support the construction of diverse intracellular and cell-surface biological logic gates for the precise regulation of cellular behavior. In mechanistic biochemical research, split inteins enable photocatalytic proximity labeling and site-specific tagging, allowing the preparation of homogeneous protein samples carrying precise post-translational modifications such as ubiquitination and polyglutamylation for chromatin interactome analysis and epigenetic studies. Moreover, covalent trapping strategies using split inteins stabilize transient enzymatic intermediates, providing unprecedented insights into molecular mechanisms such as nucleosome ubiquitination that are difficult to elucidate using conventional methods. This review systematically summarizes key technological advances in split inteins over the past decade, highlighting engineering strategies, mechanistic insights, and the development of orthogonal components. It comprehensively surveys emerging applications at the frontiers of protein research, analyzes current core challenges, and proposes future directions, particularly emphasizing artificial intelligence-driven de novo design and novel splicing pathways to break existing technical bottlenecks. By enabling traceless, efficient, and versatile protein manipulation, split inteins continue to serve as indispensable tools that drive innovation in protein engineering and fundamental life science research.
3.Investigations of tick habitats and potential pathogens carried in urban environments of Jiangsu Province
Zhi-ming WU ; Ye TIAN ; Wei-fang YANG ; Hong-na CHEN ; Jian GAO ; Hui LIU ; Yu-fu ZHANG ; Gan CAO ; Hong-liang CHU
Acta Parasitologica et Medica Entomologica Sinica 2026;33(3):192-197
Objective To investigate the species composition, distribution, density, and pathogen-carrying status of host-seeking ticks in urban environments of Jiangsu Province, and to provide a scientific basis for the prevention and control of tick-borne diseases in urban settings. Methods From April to September 2023, a survey on host-seeking ticks was conducted in three types of habitats (city parks, residential areas, and street greenbelts) across 54 counties (cities, districts) of 13 prefecture-level cities in Jiangsu Province by using the flagging method. RStudio 4.4.3 (Windows version) was employed to perform chi-square test analysis on the species composition of ticks across different months, and Friedman test (for multiple paired samples) was applied to analyze monthly changes in the average tick density index among different habitats. Quantitative real-time PCR was performed to detect pathogens in the captured ticks. Results A total of 863 host-seeking ticks were captured from 54 habitats in 24 counties (cities, districts) of 11 prefecture-level cities (Nanjing, Wuxi, Changzhou, Suzhou, Nantong, Huai'an, Yancheng, Yangzhou, Zhenjiang, Taizhou, and Suqian) in Jiangsu Province, whereas no ticks were captured in Xuzhou and Lianyungang. The collected ticks belonged to three species, with Haemaphysalis longicornis being the dominant species (accounting for 82.62%), followed by Haemaphysalis flava and Hae. phasiana. The average density index of ticks in positive habitats was 3.20 ticks/ (flag·100 m). In terms of tick density among prefecture-level cities, Wuxi had the highest density[13.55 ticks/(flag·100 m)], whereas Nanjing and Taizhou had the lowest[both,0.20 ticks/(flag·100 m)]. With respect to the types of positive habitats,46 positive city parks,7 positive residential areas, and 1 positive street greenbelt were found, with the average tick density index being 3.46, 1.86, and 3.60 ticks/flag · 100 m, respectively. No statistically significant differences were observed in the monthly variations in the average tick density index among different habitats (P>0.05). Pathogen detection showed no Bandavirus dabieense, Rickettsia, or Borrelia burgdorferi in the collected ticks. Conclusions Host-seeking ticks have established populations in urban environments across most prefecture-level cities in Jiangsu Province, with Hae. longicornis identified as the dominant species. City parks serve as the primary breeding habitats for these ticks. Strengthening tick surveillance and control measures in densely populated and frequently visited areas, such as city parks and residential neighborhoods, is crucial for the effective prevention and control of urban tick-borne diseases.
4.Value of retinal multimodal imaging in the diagnosis and treatment of cerebrovascular and neurological disorders
Yu LIU ; Zifeng ZHANG ; Manhong LI ; Yusheng WANG ; Xiaolin GAN ; Jiaxing SUN
International Eye Science 2026;26(11):1956-1961
As an extension of the central nervous system, the retina is the only tissue in the body that allows direct in vivo observation of both neural and vascular structures, offering a unique non-invasive window for the assessment of cerebral neurovascular diseases. Recent studies have shown that multimodal imaging techniques—such as fundus photography, optical coherence tomography(OCT), and OCT angiography(OCTA)—enable quantitative analysis of retinal indicators including vascular caliber, fractal dimension, retinal nerve fiber layer thickness, and microvascular density. These metrics can, to some extent, reflect the severity and progression risk of cerebrovascular and neurodegenerative diseases such as stroke, Alzheimer's disease, and Parkinson's disease. Consequently, retinal imaging holds promise as a powerful tool for early screening, risk stratification, and treatment monitoring. This article systematically reviews the application of retinal imaging technologies in the diagnosis and management of cerebral neurovascular disorders, with a particular focus on the important role of artificial intelligence(AI)-driven image analysis in enhancing screening efficiency, improving risk assessment accuracy, and promoting multidisciplinary collaborative care, thereby providing insights for clinical translation.
5.Efficacy and Safety of Qihuang Acupuncture Theory Combined with Opioid Analgesics in the Treatment of Moderate to Severe Cancer Pain in Lung Cancer Patients:a Randomize-Controlled Trial
Yingqi WANG ; Ruifang YU ; Jinpeng HUANG ; Guiya LIAO ; Ziyan GAN ; Zhenhu CHEN ; Xiaobing YANG ; Chunzhi TANG
Journal of Traditional Chinese Medicine 2025;66(4):358-366
ObjectiveTo observe the analgesic efficacy and safety of Qihuang acupuncture theory combined with opioid analgesics in patients with moderate to severe cancer pain due to lung cancer. MethodsPatients with moderate to severe cancer pain from lung cancer were randomly divided into Qihuang acupuncture group and control group, with 33 cases in each group. The control group was treated with long-acting opioid analgesics at maintenance doses and supplementary analgesic medications as needed. In case of breakthrough pain, short-acting opioids were used for rescue. The Qihuang acupuncture group received Qihuang acupuncture treatment in addition to the treatment used in the control group, administered once every other day, with 3 sessions constituting one treatment course. The treatment duration for both groups was 5 days. The primary outcome was the change in pain intensity, measured using the numerical rating scale (NRS) before and after treatment, and the NRS change rate was calculated. Secondary endpoints included the daily NRS change rate, the Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) score, the European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire (EORTC QLQ-C30) score, and the 24-hour equivalent hydrocodone sustained-release tablet dose. Laboratory tests, including routine blood, urine, stool, liver function, and kidney function, were performed before and after treatment. Adverse events were recorded throughout the trial. ResultsAll patients completed the trial, and both groups showed a decrease in average NRS scores and PS scores after treatment, with the Qihuang acupuncture group showing lower average NRS scores and PS scores than the control group (P<0.05 or P<0.01). After treatment, the NRS change rate in the Qihuang acupuncture group was (0.42±0.17), significantly higher than that in the control group (0.14±0.27, P<0.01). The daily NRS change rate during treatment was also higher in the Qihuang acupuncture group compared to the control group (P<0.01). The Qihuang acupuncture group showed an increase in overall health status and functional scores in the EORTC QLQ-C30, and a decrease in symptom scores for fatigue, nausea and vomiting, pain, dyspnea, insomnia, appetite loss, constipation, and financial difficulties. In contrast, overall health status and constipation scores in the control group increased, while scores of fatigue, nausea and vomiting, pain, and appetite loss decreased (P<0.05 or P<0.01). After treatment, the 24-hour equivalent hydrocodone sustained-release tablet dose did not show significant difference in the Qihuang acupuncture group (P>0.05), while the control group showed a significant increase in the 24-hour dose (P<0.01). No significant abnormalities were observed in laboratory tests before and after treatment in either group. During the study, the incidence of nausea and vomiting as well as constipation in the Qihuang acupuncture group was both 3.03% (1/33), while the incidence in the control group was 27.27% (9/33) and 36.36% (12/33), respectively, with the Qihuang acupuncture group showing significantly lower incidence (P<0.01). No serious adverse reactions were observed in either group. ConclusionQihuang acupuncture therapy combined with opioid analgesics is more effective than using opioids alone in relieving pain in patients with moderate to severe cancer pain due to lung cancer. It can improve the patients' physical condition and quality of life, reduce the dose of opioid analgesics, and has good safety.
6.Clinical Observation on Clinical Efficacy of Traditional Chinese Medicine Sequential Therapy for the Treatment of Patients with Psoriasis Vulgaris in Shenzhen
Qinmei GU ; Binyan LI ; Yanjie LIU ; Yu SU ; Rong ZHANG ; Haifang GAN
Journal of Guangzhou University of Traditional Chinese Medicine 2025;42(5):1126-1132
Objective To observe the clinical efficacy of traditional Chinese medicine(TCM)sequential therapy in treating patients with psoriasis vulgaris in Shenzhen,and to explore the syndrome differentiation and treatment for the patients with psoriasis vulgaris in Shenzhen region.Methods From January 2019 to February 2024,70 cases of psoriasis vulgaris admitted to Shenzhen Bao'an Traditional Chinese Medicine Hospital Affiliated to Guangzhou University of Chinese Medicine(Shenzhen Bao'an Traditional Chinese Medicine Hospital Group)were retrospectively analyzed.The patients were divided into the observation group(39 cases)and the control group(31 cases)according to the treatment plans.In the control group,only topical application of Calcipotriol Ointment was given throughout the treatment,while in the observation group the patients were treated with TCM sequential therapy according to the illness stage on the basis of treatment for the control group,i.e.,internal administration of modified Shuiniujiao Huanglian Decoction was given in the acute stage and modified Sijunzi Shuiniujiao Decoction was given in the remission stage.Both groups were treated for 3 months.Before and after the treatment,the changes of Psoriasis Area and Severity Index(PASI)scores,Dermatology Life Quality Index(DLQI)scores and TCM syndrome scores in the two groups were observed.After treatment,the clinical efficacy and drug safety of the two groups were evaluated.Results(1)After 3 months of treatment,the total effective rate of the observation group was 89.74%(35/39),and that of the control group was 74.19%(23/31).The intergroup comparison(tested by chi-square test)showed that the efficacy of the observation group was significantly superior to that of the control group(P<0.05).(2)After treatment,the PASI scores for evaluating the severity of skin lesions in the two groups were significantly decreased compared with those before treatment(P<0.05),and the decrease in the observation group was significantly superior to that in the control group(P<0.05).(3)After treatment,the DLQI scores for evaluating the quality of life in the two groups were significantly decreased compared with those before treatment(P<0.05),and the decrease in the observation group was significantly superior to that in the control group(P<0.05).(4)After treatment,the scores of TCM syndromes such as erythema,itching,vexation and dry mouth in the two groups were significantly decreased compared with those before treatment(P<0.05),and the decrease in the observation group was significantly superior to that in the control group(P<0.05).(5)During the treatment period,no obvious adverse reactions occurred in the two groups of patients,with high safety.Conclusion On the basis of conventional western medicine treatment,application of TCM sequential therapy exerts certain clinical efficacy in treating patients with psoriasis vulgaris in Shenzhen region,and the combined therapy is effective on controlling the patients'illness conditions,significantly alleviating the symptoms and improving the quality of life of the patients.
7.COCKROACH SURVEILLANCE IN LANZHOU FROM 2016 TO 2023
Ying ZHANG ; Jing ZUO ; Qing-Ming SHI ; Zi-Peng LI ; Wen-Juan BA ; Zhi-Qing LI ; Ai-Miao LIAO ; Jing-Jing YU ; Guo-Jing BAO ; Xing LI ; Jun GAN ; Xiao-Lei YE
Acta Parasitologica et Medica Entomologica Sinica 2025;32(2):119-122
Objective To investigate the population composition,seasonal dynamics,and infestation levels of cockroaches in Lanzhou,China,and to provide information for the scientific development of cockroach control strategies.Methods Monitoring was conducted at three locations using the sticky trap method.Habitats included farm product markets,catering establishments,hotels,hospitals,and residential areas.Results From 2016 to 2023,the average cockroach density was 0.77 insects per board,with an average infestation rate of 10.84%.Blattella germanica was the dominant species.Seasonal density of cockroaches showed an approximately unimodal distribution,peaking in September.The highest average density and infestation rates were observed in farm product markets.Conclusions Cockroach density and infestation levels in Lanzhou remained relatively low.A comprehensive prevention and control strategy focusing on environmental management in key areas should be implemented according to the seasonal fluctuations.
8.Feasibility study on conduction system fluorescence imaging by anterograde perfusion with fluorescent dyes-labeled antibody in ex vivo rat hearts
Yifei REN ; Kai YU ; Changping GAN ; Ke DIAN
Chinese Journal of Clinical Thoracic and Cardiovascular Surgery 2025;32(11):1621-1628
Objective To evaluate the feasibility of imaging the rat cardiac conduction system (CCS) using transaortic antegrade perfusion of Alexa Fluor 633-labeled antibodies targeting hyperpolarization-activated cyclic nucleotide-gated cation channel 4 (HCN4) and connexin (Cx). The study also sought to optimize antibody dosage, perfusion duration, and assess the photostability of the dye. Methods Ex vivo rat heart model with transaortic antegrade perfusion was established using 33 male SPF-grade Sprague-Dawley (SD) rats. Primary and secondary antibody solutions were sequentially perfused in an antegrade manner. After perfusion for predetermined durations, the atrioventricular junction was observed, and the fluorescence intensity of the corresponding area was recorded. Five dose-gradient groups (n=3 rats/group), five perfusion time-gradient groups (n=3 rats/group), and ten continuous LED light exposure time-gradient groups (using 3 rats prepared with a fixed dose and time) were established to observe and record regional fluorescence intensity. Standard immunofluorescence staining was performed on both paraffin and frozen sections for comparative histological analysis. Results A region of aggregated red fluorescent signal was observed in the atrioventricular junction. Following semi-quantitative fluorescence intensity analysis of HCN4/Cx43 and validation through comparative histology, this structure was identified as the atrioventricular node (AVN) region. The AVN-to-background fluorescence intensity ratio showed no statistically significant differences among groups with increasing antibody dosage (P>0.05). The ratio increased with longer antibody perfusion times. Furthermore, no statistically significant differences in the ratio were observed among groups with extended light exposure (P>0.05). Conclusion Transaortic antegrade perfusion of fluorescently labeled antibodies can successfully image the AVN within the CCS of ex vivo rat hearts. Increasing the antibody dosage does not significantly improve the AVN imaging effect. Longer antibody perfusion time results in better imaging quality of the AVN. The fluorescent dye maintains sufficient visualization of the AVN even after prolonged (8 h) exposure to light.
9.Effect of mindfulness-based cognitive therapy in the sense of personal control and illness perception of young and middle-aged patients after PCI
Weiling HAO ; Xiaoxiang YU ; Yanfang ZHAO ; Jiayu HAN ; Jing YU ; Shunna GAN ; Minrou XU ; Ying XU ; Meng YUAN ; Mingxing XU
Chinese Journal of Practical Nursing 2025;41(22):1681-1687
Objective:To investigate the effect of mindfulness-based cognitive therapy on the sense of personal control and illness perception of young and middle-aged patients after percutaneous coronary intervention (PCI), so as to provide theoretical and practical guidance for the psychological care of patients after PCI.Methods:A randomized controlled trial was conducted. From January 2022 to December 2023, young and middle-aged patients after PCI admitted to the Department of Cardiology, Qinhuai Medical District, Eastern Theater Command General Hospital of the Chinese People′s Liberation Army were selected as the research subjects by convenient sampling method, patients were divided into the experimental group and the control group by the random number table method. The control group was given routine nursing, and the experimental group was given mindfulness-based cognitive therapy on the basis of routine nursing. The Personal Mastery Scale (PMS), Cardiac Self-Efficacy Questionnaire (CSEQ), and Brief Illness Perception Questionnaire (BIPQ) were used to evaluate personal sense of control, self-efficacy, and illness perception before and after the intervention respectively.Results:A total of 80 young and middle-aged patients after PCI were included. There were 40 cases in the control group, including 25 males and 15 females, aged (49.43 ± 5.55) years old. There were 40 cases in the experimental group, including 19 males and 21 females, aged (49.03 ± 4.19) years old. Before the intervention, there was no statistically significant difference in the PMS, CSEQ and BIPQ scores between the two groups of patients (all P>0.05). After the intervention, the PMS, CSEQ scores of the patients in the experimental group were (23.03 ± 2.54), (45.85 ± 8.16) points respectively, which were higher than (21.95 ± 2.28), (39.05 ± 8.78) points in the control group, the BIPQ score of the patients in the experimental group was(39.63 ± 8.12) points, which was lower the (45.45 ± 8.64) points in the control group, the differences were statistically significant ( t=-2.00, -3.59, 3.11, all P<0.05). Conclusions:Mindfulness-based cognitive therapy can effectively improve the sense of personal control and self-efficacy of young and middle-aged patients after PCI, reduce the sense of threat to the disease.
10.Expert consensus on infection prevention and control of Creutzfeldt-Jakob disease in medical institutions
Tianxiang GE ; Yangyang JIA ; Chunhui LI ; Jianrong HUANG ; Xiujuan MENG ; Xiaodong GAO ; Jingping ZHANG ; Fu QIAO ; Lijuan XIONG ; Hui LIANG ; Wei LI ; Haiyan LOU ; Wenjuan WU ; Tianxin XIANG ; Jiansen CHEN ; Biao ZHU ; Kaijin XU ; Zhihui ZHOU ; Hongliu CAI ; Meihong YU ; Yan ZHANG ; Yanwan SHANGGUAN ; Haiting FENG ; Hangping YAO ; Lei GUO ; Tieer GAN ; Weihong ZHANG ; Jimin SUN ; Ye LU ; Qun LU ; Meng CAI ; Jin SHEN ; Yunsong YU ; Anhua WU ; Liu-yi LI ; Tingting QU
Chinese Journal of Infection Control 2025;24(4):437-450
Creutzfeldt-Jakob disease(CJD)is a rapidly progressive and fatal neurodegenerative disorder caused by prions,with certain infectivity and iatrogenic transmission risks.With the rapid progress and application of new dia-gnostic biomarkers and detection methods,as well as the construction and improvement of surveillance and reporting systems,the detection of CJD in patients domestically and internationally has shown an increasing trend year by year.Due to its long incubation period and heterogeneity of early symptoms,early identification and diagnosis of the disease is difficult,increasing the risk of transmission within medical institutions.Currently,there is a lack of con-sensus on the infection prevention and control of CJD.In order to timely identify and diagnose CJD as well as effec-tively block its transmission in medical institutions,this consensus summarizes 15 clinical concerns and formulates 24 specific recommendations based on the latest domestic and international research findings and clinical evidence,as well as combines with clinical practice,aiming to standardize healthcare-associated infection prevention and control measures for CJD and reduce its transmission risk in medical institutions.


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