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.

Objective To study the need for blood compatibility evaluation of medical devices that come into indirect contact with blood in order to accurately evaluate the risk of their interaction with blood.Methods Seven medical devices with indirect contact with blood were selected as samples including extension tubes of central venous catheters,port bodies of implantable drug delivery devices,infusion sets,receiving lines of dialysis equipment,auxiliary lines of left ventricular assist devices,blood monitors and catheter holders,with high-density polyethylene as the negative control,glass beads as the positive control and blank whole blood or plasma for the blank control.Partial thromboplastin time(PTT)test,platelet count test and hematology test(white blood cell and red blood cell count)were performed by direct contact method and indirect contact method,respectively.In the direct contact method,whole blood or plasma was in direct contact with the sample;while in the indirect contact method,whole blood or plasma was not in direct contact with the extraction solution,with no direct contact with the sample.Results With the indirect contact method the ratios(expressed as a percentage)of the PTT,platelate,WBC and RBC counts of the samples,positive and negative controls to those of the blank control were all higher than those with the direct contact method,and the indirect contact method had the sensitivity lower than that of the direct contact method.Conclusion Medical devices indirectly contacting blood have low risks for causing coagulation and platelet and hematologic adverse reactions,which are suggested to be evaluated for hemolysis testing only in case of the history of safe clinical use.[Chinese Medical Equipment Journal,2025,46(8):44-49]

Objective:To determine the incidence of acute focal bacterial nephritis (AFBN) in children with febrile urinary tract infections (UTI) and to identify associated risk factors.Methods:A retrospective cohort study included 181 children hospitalized with febrile UTI at Fujian Children′s Hospital from April 2021 to September 2023. Demographic data, clinical manifestations, and laboratory findings were collected. Patients were categorized into AFBN group and non-AFBN group based on AFBN diagnosis. The incidence of AFBN within this febrile UTI cohort was determined. The diagnostic value for pre-antibiotic blood white blood cell (WBC) count and C-reactive protein (CRP) level, along with post-treatment fever duration and pyuria duration for AFBN was evaluated using the area under curve (AUC) of the receiver operating characteristic (ROC).Results:The cohort comprised 181 children with febrile UTI (100 boys and 81 girls), age of 0.6 (0.3, 1.0) years. Eleven patients (6.1%) were diagnosed with AFBN. For predicting AFBN, the AUC was 0.71 (95% CI 0.55-0.85, P=0.026) for pre-antibiotic WBC count and 0.80 (95% CI 0.71-0.90, P=0.001) for pre-antibiotic CRP level, with optimal cutoff values of 16.0×10 9/L and 80.1 mg/L, respectively. For post-treatment parameters, the AUC was 0.79 (95% CI 0.69-0.92, P=0.001) for fever duration and 0.84 (95% CI 0.72-0.97, P<0.001) for pyuria duration, with optimal cutoff values of 1.9 d and 5.5 d, respectively. The combination of pre-antibiotic WBC count >16.0×10 9/L and CRP>80.1 mg/L yielded a sensitivity of 0.73 and a specificity of 0.86 for AFBN prediction. Similarly, the combination of post-treatment fever duration ≥2 d and pyuria duration >5 d demonstrated a sensitivity of 0.82 and specificity of 0.88. Conclusions:AFBN incidence was 6.1% in this cohort of children with febrile UTI. AFBN should be highly suspected in febrile UTI children presenting with either a pre-antibiotic WBC count >16.0×10 9/L and CRP >80.1 mg/L, or a post-treatment fever duration ≥2 d and pyuria duration >5 d.

Objective:To investigate the clinical characteristics of urea cycle disorder (UCD), the efficacy and safety of glyceryl phenylbutyrate (GPB) therapy in pediatric patients with UCD.Methods:This study was a retrospective, single-arm, multicenter clinical study. The clinical data of 20 pediatric patients with UCD who received GPB treatment at 9 hospitals nationwide between December 2021 and August 2024 were collected. The clinical manifestations, laboratory results, and molecular genetic characteristics were analyzed, ammonia levels and other laboratory results were evaluated pre-post GPB therapy by paired t-tests or Wilcoxon tests. Results:Among the 20 pediatric patients with UCD, there were 8 males and 12 females, and the onset age was 2.8 (1.4, 5.7) years. The ammonia levels were 174 (125, 342) μmol/L at first onset. The symptoms included vomiting in 6 cases, drowsiness in 5 cases, epilepsy in 5 cases, developmental delay in 5 cases, psychiatric and behavioral abnormalities in 3 cases, and lethargy in 1 case, and 18 cases exhibited abnormal liver function. Twenty cases included 6 UCD subtypes, with 11 cases being ornithine transcarbamylase deficiency. A total of 27 variants were identified, 11 (41%) of which were novel. The age of patients who began GPB therapy was 4.0 (1.5, 6.6) years. Ten cases stopped GPB after 4.2 (3.4, 5.3) months, with 4 patients undergoing liver transplantation and 6 discontinuing for financial reasons. The remaining ten patients continued GPB therapy for 11.6 (8.6, 14.0) months. The duration of GPB treatment was 6.0 (4.2, 12.3) months, at the final visit, the levels of ammonia, platelets and aspartate aminotransferase were lower compared to those of pre-treatment (all P<0.05). The serum albumin level was higher than that of pre-treatment ( P=0.016). Two patients suffered only one episode of acute hyperammonaemia, with ammonia levels of 232 and 141 μmol/L, respectively. Nine cases experienced adverse effects potentially related to GPB, decreased appetite in 6 cases, vomiting in 3 cases, abnormal skin oil odor in 2 cases, somnolence, fatigue and diarrhea each in 1 case, with symptoms improved within 6 (3, 10) days. Conclusions:UCD primarily manifests with neurological and gastrointestinal symptoms, and early diagnosis of UCD could be achieved through the analysis of ammonia. GPB may effectively reduce ammonia levels in UCD pediatric patients, with favorable safety and tolerability.

Objective To investigate the differences in demographic characteristics,reproductive health status,and the distribution of pregnancy-related diseases between couples conceived via assisted reproductive technology(ART)and naturally conceived couples,and to analyze the impact of ART treatment on the incidence of preterm birth(PTB)in singleton and twin and multiple pregnancies.Methods We conducted a retrospective analysis of the maternal and infant cohort data of Jing'an District from 2013 to 2020.Based on the conception method,the subjects were categorized into two groups:the ART group and the natural conception group.Chi-square test was applied to compare baseline characteristics and disease distributions differences between the two groups,and logistic regression models were used to evaluate the association between ART and the PTB risks.A causal mediation model was used to evaluate the mediating effect of twin and multiple pregnancy in the relationship between ART and PTB.Results A total of 117 717 parturients were included,6 265 in the ART group and 111 452 in the natural conception group.Compared with the natural conception group,couples in the ART group were significantly older and had a higher prevalence of reproductive system diseases.The incidences of diabetes and hypertensive disorders during pregnancy in ART parturient were 13.76%and 9.99%,respectively,which were significantly higher than 7.88%and 4.75%in the natural conception group(both P<0.001).The overall PTB rate in the ART group was 14.81%,higher than 5.35%in the natural conceptions group(P<0.001).The PTB rate in ART for singleton pregnancies in the ART group was 6.40%,higher than 4.83%in the natural conception group(P<0.001),while the PTB rate in ART for twin and multiple pregnancies in the ART group was 53.97%,lower than 60.42%in the natural conception group(P<0.05).Mediation analysis showed that 97.99%of the effect of ART on PTB was mediated by twin and multiple pregnancy,with ART increasing the PTB risk by 3.44 times through multiple pregnancy.Conclusion The overall PTB rate of ART recipients is higher than that of natural recipients,but ART does not increase the PTB risk in singleton and twin and multiple pregnancies.Twin and multiple pregnancy is the key mediating factor contributing to PTB in ART-conceived recipients.Compared with naturally conceived couples,ART conception couples own more advanced maternal age,and have higher risks of suffering gestational diabetes,gestational hypertension,and PTB.

Objective This study investigated feasible cases and their significance in promoting the"generalized"development of inspection through digital-intelligent equipment.Methods A qualitative research approach was used,involving interviews conducted between February 2025 and March 2025 with experts in traditional Chinese medicine diagnostics,clinical research methodology,medical engineering integration,and related disciplines,using both online and offline methods.In accordance with the Consolidated Criteria for Reporting Qualitative Research,feasible cases involving the specific application of digital equipment in various parts of observation were collected through item enrichment.The significance of extending observation capabilities via these cases was analyzed,along with the overall implications of integrating digital technologies with traditional inspection method.Results Interviews were completed with 11 experts from domestic universities and research institutes in the fields of traditional Chinese medicine diagnosis,medical engineering integration,and related disciplines.A total of 78 feasible cases of digital-intelligent inspection were identified,along with 69 insights regarding the significance of enhancing the inspection capabilities.These insights were synthesized into two dimensions and 23 holistic meanings.The first dimension is to expand the scope of inspection,including obtaining internal environmental characteristics,observing external environmental characteristics,expanding thermodynamic characteristic data,and crossing time and space.The second dimension is to improve the quality of observation and diagnosis information collection and analysis,including 19 specific meanings,such as standardized collection environment,objective quantification,and refined observation.Conclusion Digital-intelligent equipment plays a significant role in expanding the scope of inspection content and achieving high-quality acquisition and analysis of extensive inspection information.These advancements extend and enrich the capabilities of traditional inspection method in traditional Chinese medicine.

Objective:To determine the incidence of acute focal bacterial nephritis (AFBN) in children with febrile urinary tract infections (UTI) and to identify associated risk factors.Methods:A retrospective cohort study included 181 children hospitalized with febrile UTI at Fujian Children′s Hospital from April 2021 to September 2023. Demographic data, clinical manifestations, and laboratory findings were collected. Patients were categorized into AFBN group and non-AFBN group based on AFBN diagnosis. The incidence of AFBN within this febrile UTI cohort was determined. The diagnostic value for pre-antibiotic blood white blood cell (WBC) count and C-reactive protein (CRP) level, along with post-treatment fever duration and pyuria duration for AFBN was evaluated using the area under curve (AUC) of the receiver operating characteristic (ROC).Results:The cohort comprised 181 children with febrile UTI (100 boys and 81 girls), age of 0.6 (0.3, 1.0) years. Eleven patients (6.1%) were diagnosed with AFBN. For predicting AFBN, the AUC was 0.71 (95% CI 0.55-0.85, P=0.026) for pre-antibiotic WBC count and 0.80 (95% CI 0.71-0.90, P=0.001) for pre-antibiotic CRP level, with optimal cutoff values of 16.0×10 9/L and 80.1 mg/L, respectively. For post-treatment parameters, the AUC was 0.79 (95% CI 0.69-0.92, P=0.001) for fever duration and 0.84 (95% CI 0.72-0.97, P<0.001) for pyuria duration, with optimal cutoff values of 1.9 d and 5.5 d, respectively. The combination of pre-antibiotic WBC count >16.0×10 9/L and CRP>80.1 mg/L yielded a sensitivity of 0.73 and a specificity of 0.86 for AFBN prediction. Similarly, the combination of post-treatment fever duration ≥2 d and pyuria duration >5 d demonstrated a sensitivity of 0.82 and specificity of 0.88. Conclusions:AFBN incidence was 6.1% in this cohort of children with febrile UTI. AFBN should be highly suspected in febrile UTI children presenting with either a pre-antibiotic WBC count >16.0×10 9/L and CRP >80.1 mg/L, or a post-treatment fever duration ≥2 d and pyuria duration >5 d.

Objective:To investigate the clinical characteristics of urea cycle disorder (UCD), the efficacy and safety of glyceryl phenylbutyrate (GPB) therapy in pediatric patients with UCD.Methods:This study was a retrospective, single-arm, multicenter clinical study. The clinical data of 20 pediatric patients with UCD who received GPB treatment at 9 hospitals nationwide between December 2021 and August 2024 were collected. The clinical manifestations, laboratory results, and molecular genetic characteristics were analyzed, ammonia levels and other laboratory results were evaluated pre-post GPB therapy by paired t-tests or Wilcoxon tests. Results:Among the 20 pediatric patients with UCD, there were 8 males and 12 females, and the onset age was 2.8 (1.4, 5.7) years. The ammonia levels were 174 (125, 342) μmol/L at first onset. The symptoms included vomiting in 6 cases, drowsiness in 5 cases, epilepsy in 5 cases, developmental delay in 5 cases, psychiatric and behavioral abnormalities in 3 cases, and lethargy in 1 case, and 18 cases exhibited abnormal liver function. Twenty cases included 6 UCD subtypes, with 11 cases being ornithine transcarbamylase deficiency. A total of 27 variants were identified, 11 (41%) of which were novel. The age of patients who began GPB therapy was 4.0 (1.5, 6.6) years. Ten cases stopped GPB after 4.2 (3.4, 5.3) months, with 4 patients undergoing liver transplantation and 6 discontinuing for financial reasons. The remaining ten patients continued GPB therapy for 11.6 (8.6, 14.0) months. The duration of GPB treatment was 6.0 (4.2, 12.3) months, at the final visit, the levels of ammonia, platelets and aspartate aminotransferase were lower compared to those of pre-treatment (all P<0.05). The serum albumin level was higher than that of pre-treatment ( P=0.016). Two patients suffered only one episode of acute hyperammonaemia, with ammonia levels of 232 and 141 μmol/L, respectively. Nine cases experienced adverse effects potentially related to GPB, decreased appetite in 6 cases, vomiting in 3 cases, abnormal skin oil odor in 2 cases, somnolence, fatigue and diarrhea each in 1 case, with symptoms improved within 6 (3, 10) days. Conclusions:UCD primarily manifests with neurological and gastrointestinal symptoms, and early diagnosis of UCD could be achieved through the analysis of ammonia. GPB may effectively reduce ammonia levels in UCD pediatric patients, with favorable safety and tolerability.

Objective To investigate the effect of splenectomy on the repair of full-thickness skin tissue defects,as well as the impact of different recovery times after splenectomy on the healing of skin tissue defects.Methods According to a random number table,39 8-week-old female C57 mice were randomly divided into three groups:sham surgery group(sham group,n=13),splenectomy group with 3 days of recovery(Spx3d group,n=13),and splenectomy group with 3 weeks of recovery(Spx3w group,n=13).Full-thickness skin defects were created on the backs of the mice in each group.The wound healing conditions at different times after skin defects were observed,and the wound healing rates after the injury were calculated.Peripheral blood cell analysis was performed on day 14 after the defect,and tissue samples from the wound area were taken for hematoxylin and eosin(HE)staining to observe the granulation tissue thickness at the defect site and the re-epithelialization rate.Masson's trichrome staining was used to observe the proportion of collagen fibers.Results After splenectomy and sham surgery,the mice recovered well without significant discomfort.From 1 to 14 days after the skin defect modeling,the wound areas of the mice in all three groups gradually decreased.Compared with sham group,the wound areas were smaller in Spx3d and Spx3w groups at 3,5 and 7 days after the injury,and the differences were statistically significant(P<0.05).The wound healing rates were also significantly higher(P<0.05).Moreover,at 3 days and 5 days after the injury,the wound healing rates of Spx3d group were significantly higher than those of Spx3w group(P<0.05 or P<0.01).The peripheral blood white blood cell(WBC)count in Spx3w group was significantly higher than that in sham group and Spx3d group(P<0.01).The platelet counts in both sham group and Spx3w group were significantly higher than that in Spx3d group(P<0.05).Additionally,the lymphocyte and neutrophil counts in Spx3w group were markedly higher than those in sham group(P<0.05).No statistically significant differences in red blood cell(RBC)counts were observed among the three groups(P>0.05).HE staining results showed that compared with sham group,the wound healing of the mice in Spx3d and Spx3w groups were better,and the thickness of the granulation tissue in Spx3d group were better than that in Spx3w group.At 7 days,the thickness of the granulation tissue in Spx3d and Spx3w groups was significantly higher than that in sham group(P<0.01,P<0.05)and the re-epithelialization rate in Spx3d group was significantly higher than that in sham group and Spx3w group(P<0.05).At 14 days,the re-epithelialization rates of Spx3d and Spx3w groups were significantly higher than those of sham group(P<0.05).The results of Masson's staining showed that the collagen fiber proportion in the wounds of Spx3d group at 7 and 14 days and that of Spx3w group at 14 days were significantly higher than that in sham group(P<0.05).Conclusion The healing of skin defects in mice is accelerated after splenectomy,and the recovery time after splenectomy has a certain effect on the healing of skin defects.

Objective To establish a stable,reliable,and clinically relevant porcine model of endotoxin-induced acute respiratory distress syndrome(ARDS).Methods Ten 8-month-old male Bama minipigs were deeply sedated,followed by invasive mechanical ventilation and electrocardiographic monitoring.Lipopolysaccharide(LPS)was intravenously pumped at 600 μg/(kg·h)for 3 hours,then maintained at 15 μg/(kg·h)thereafter.Dynamic monitoring was performed at five time points after LPS injection(LPS 0,1,3,5,and 8 h),including arterial blood gas analysis and chest computed tomography(CT)scans.Pathological examination of lung tissues obtained via bronchoscopic biopsy(HE staining and transmission electron microscopy)was conducted.These indicators were comprehensively used to evaluate the success of the animal model.Results At 5 hours after LPS administration,8 minipigs developed symptoms such as skin cyanosis,elevated body temperature,and respiratory distress.The oxygenation index decreased to<300 mmHg.Chest CT scans showed diffuse pulmonary infiltrates.Histopathology revealed alveolar edema and hyaline membrane formation.Transmission electron microscopy demonstrated disruption of pulmonary blood-air barrier,depletion of lamellar bodies in type Ⅱ pneumocytes,inflammatory cell infiltration,and exudation of plasma proteins and fibrin.Compared with LPS 0 h,at LPS 8 h,the oxygenation index and arterial blood pH were significantly decreased(P<0.001),while blood lactic acid and serum potassium were significantly increased(P<0.05);serum calcium and base excess were significantly decreased(P<0.05),and the lung injury score based on HE-stained lung sections was significantly increased(P<0.01).Conclusion The porcine ARDS model established by continuous LPS injection can dynamically simulate the pathophysiological characteristics and typical pathological manifestations of clinical septic ARDS,making it an effective tool to study the pathogenesis,prevention,and treatment strategies of septic ARDS.