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 explore the mechanism by which curcumin improves behavioral deficits in mice with Parkinson's disease(PD)through fecal microbiota transplantation.Methods A subacute model of PD in mice was induced by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP).Fecal microbiota from both the model group and the curcumin(Cur)-treated group(80 m g/kg)were collected and analyzed.The experiment involving fecal microbiota transplantation was structured into four distinct groups,fecal microbiota solvent transplantation group(FMTcon),model fecal microbiota transplantation group(FMTmodel),MPTP-induced model group(model),and model group subjected to fecal microbiota transplantation following curcumin treatment(model+FMTCur).The motor skills of the mice were assessed by using rod rotation,pole climbing experiment,and open field tests.Immunofluorescence techniques were employed to observe the expression tyrosine hydroxylase(TH)-positive neurons in the substantia nigra of the brain.Additionally,the gene expression of tumor necrosis factor-α(TNF-α)in the midbrain of mice was analyzed,alongside the protein expression of nuclear factor-κB(NF-κB)and nucleotide binding oligomerization domain-like receptor protein 3(NLRP3).Results The subacute PD animal model in mice was successfully established,and fecal microbiota were separated and gathered.The model group exhibited significant motor impairment,as evidenced by a shortened rod rotation time(P＜0.05),prolonged pole climbing time(P＜0.05),significantly reduced total movement distance within the open field(P＜0.001),and decreased time spent in the central zone(P＜0.01).The relative expression level of TH+neurons in the substantia nigra was significantly reduced(P＜0.01).Moreover,mRNA expression of TNF-α in the midbrain increased significantly(P＜0.01),along with significant elevations in protein expression of NF-κB(P＜0.001),phosphorylated NF-κB(p-NF-κB)(P＜0.01),NLRP3(P＜0.001),and Caspase-1(P＜0.01).The transplanted model microbial group(FMTmodel)also exhibited motor impairment,manifested by a trend of shortened rod rotation time,prolonged pole climbing time,a significant decrease in total movement distance within the open field(P＜0.01),and a trend of shortened time spent in the central zone.The relative expression level of TH+neurons in the substantia nigra decreased significantly(P＜0.05).Additionally,mRNA expression of TNF-α in the midbrain increased significantly(P＜0.01),along with notable elevations in the protein expression of NF-κB(P＜0.05),and Caspase-1(P＜0.01).Treatment with curcumin in the fecal microbiota transplantation group of mice(model+FMTCur)showed improvements in motor abilities,evidenced by shortened pole climbing time(P＜0.05),significantly prolonged rod rotation time(P＜0.01),and extended time spent in the central zone(P＜0.05).The relative expression level of TH+dopaminergic neurons in the substantia nigra increased significantly(P＜0.05).Moreover,mRNA expression of TNF-α in the midbrain decreased significantly(P＜0.01),along with notable reductions in the protein expression of NF-κB(P＜0.001),p-NF-κB(P＜0.01),NLRP3(P＜0.05),and Caspase-1(P＜0.01).Conclusion Fecal microbiota transplantation in PD model mice can induce behavioral deficits,damage TH+neurons in the substantia nigra,and trigger neuroinflammation in the brain.Subsequent curcumin treatment can ameliorate these deficits,reverse damage to TH+neurons,reduce neuroinflammatory factors,and decrease the expression of NF-κB and NLRP3 pathways.This preliminary evidence suggests that curcumin may improve Parkinsonian behavioral deficits in mice by modulating the gut microbiota.

Apical microsurgery is accurate and minimally invasive, produces few complications, and has a success rate of more than 90%. However, due to the lack of awareness and understanding of apical microsurgery by dental general practitioners and even endodontists, many clinical problems remain to be overcome. The consensus has gathered well-known domestic experts to hold a series of special discussions and reached the consensus. This document specifies the indications, contraindications, preoperative preparations, operational procedures, complication prevention measures, and efficacy evaluation of apical microsurgery and is applicable to dentists who perform apical microsurgery after systematic training.
Microsurgery/standards* ; Humans ; Apicoectomy ; Contraindications, Procedure ; Tooth Apex/diagnostic imaging* ; Postoperative Complications/prevention & control* ; Consensus ; Treatment Outcome

Pulpotomy, which belongs to vital pulp therapy, has become a strategy for managing pulpitis in recent decades. This minimally invasive treatment reflects the recognition of preserving healthy dental pulp and optimizing long-term patient-centered outcomes. Pulpotomy is categorized into partial pulpotomy (PP), the removal of a partial segment of the coronal pulp tissue, and full pulpotomy (FP), the removal of whole coronal pulp, which is followed by applying the biomaterials onto the remaining pulp tissue and ultimately restoring the tooth. Procedural decisions for the amount of pulp tissue removal or retention depend on the diagnostic of pulp vitality, the overall treatment plan, the patient's general health status, and pulp inflammation reassessment during operation. This statement represents the consensus of an expert committee convened by the Society of Cariology and Endodontics, Chinese Stomatological Association. It addresses the current evidence to support the application of pulpotomy as a potential alternative to root canal treatment (RCT) on mature permanent teeth with pulpitis from a biological basis, the development of capping biomaterial, and the diagnostic considerations to evidence-based medicine. This expert statement intends to provide a clinical protocol of pulpotomy, which facilitates practitioners in choosing the optimal procedure and increasing their confidence in this rapidly evolving field.
Humans ; Calcium Compounds/therapeutic use* ; Consensus ; Dental Pulp ; Dentition, Permanent ; Oxides/therapeutic use* ; Pulpitis/therapy* ; Pulpotomy/standards*

Intentional tooth replantation (ITR) is an advanced treatment modality and the procedure of last resort for preserving teeth with inaccessible endodontic or resorptive lesions. ITR is defined as the deliberate extraction of a tooth; evaluation of the root surface, endodontic manipulation, and repair; and placement of the tooth back into its original socket. Case reports, case series, cohort studies, and randomized controlled trials have demonstrated the efficacy of ITR in the retention of natural teeth that are untreatable or difficult to manage with root canal treatment or endodontic microsurgery. However, variations in clinical protocols for ITR exist due to the empirical nature of the original protocols and rapid advancements in the field of oral biology and dental materials. This heterogeneity in protocols may cause confusion among dental practitioners; therefore, guidelines and considerations for ITR should be explicated. This expert consensus discusses the biological foundation of ITR, the available clinical protocols and current status of ITR in treating teeth with refractory apical periodontitis or anatomical aberration, and the main complications of this treatment, aiming to refine the clinical management of ITR in accordance with the progress of basic research and clinical studies; the findings suggest that ITR may become a more consistent evidence-based option in dental treatment.
Humans ; Tooth Replantation/methods* ; Consensus ; Periapical Periodontitis/surgery*

Cemental tear is a rare and indetectable condition unless obvious clinical signs present with the involvement of surrounding periodontal and periapical tissues. Due to its clinical manifestations similar to common dental issues, such as vertical root fracture, primary endodontic diseases, and periodontal diseases, as well as the low awareness of cemental tear for clinicians, misdiagnosis often occurs. The critical principle for cemental tear treatment is to remove torn fragments, and overlooking fragments leads to futile therapy, which could deteriorate the conditions of the affected teeth. Therefore, accurate diagnosis and subsequent appropriate interventions are vital for managing cemental tear. Novel diagnostic tools, including cone-beam computed tomography (CBCT), microscopes, and enamel matrix derivatives, have improved early detection and management, enhancing tooth retention. The implementation of standardized diagnostic criteria and treatment protocols, combined with improved clinical awareness among dental professionals, serves to mitigate risks of diagnostic errors and suboptimal therapeutic interventions. This expert consensus reviewed the epidemiology, pathogenesis, potential predisposing factors, clinical manifestations, diagnosis, differential diagnosis, treatment, and prognosis of cemental tear, aiming to provide a clinical guideline and facilitate clinicians to have a better understanding of cemental tear.
Humans ; Dental Cementum/injuries* ; Consensus ; Diagnosis, Differential ; Cone-Beam Computed Tomography ; Tooth Fractures/therapy*

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 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.