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 clinical effect of percutaneous endoscopic posterolateral trans-facet lumbar interbody fusion (PE-PTLIF) in treating degenerative lumbar spondylolisthesis. METHODS: The data of 38 patients with degenerative lumbar spondylolisthesis treated with PE-PTLIF from December 2019 to June 2021 were retrospectively analyzed, including 18 males and 20 females, aged from 39 to 75 years old with an average of (60.2±8.9) years old;1 patient with L_3,4, 23 patients with L_4,5, 14 patients with L₅S₁;29 patients with degreeⅠand 9 patients with degreeⅡaccording to Meyerding grading. Operative time, intraoperative blood loss, drainage volume, postoperative hospital stay and complcations were observed, visual analogue scale (VAS) was used to evaluate degree of lumbar and leg pain before operation, 3 d and 3, 6 and 12 months after operation, respectively. Oswestry disability index (ODI) was used to evaluate degree of low back pain dysfunction before operation, 3, 6 and 12 months after operation. The modified MacNab standard was used to evaluate clinical efficacy at 12 months after operation. Dural sac cross-sectional area (DSCSA), intervertebral disc height (IDH), lumbar spondylolisthesis rate (SR), lumbar lordosis angle (LL) and segmental lordosis angle (SL) were compared before operation and 12 months after operation. Interbody fusion at 12 months was evaluated according to Bridwell intervertebral fusion standard. RESULTS: All patients were followed up for 13 to 28 months with an average of (18.47±4.12) months. The operative time was (181.68±19.34) min, intraoperative blood loss was (152.87±57.03) ml, drainage volume was (48.18±11.43) ml, and postoperative hospital stay was (9.45±2.18) d and 3 patients occurred complications. VAS of lumbar pain before operation, 3 days, 3, 6 and 12 months after operation were (6.68±1.16), (4.32±1.13), (2.18±0.70), (1.89±0.56) and (1.57±0.72), respectively. VAS of leg pain were (6.24±1.42), (2.95±1.09), (1.76±0.71), (1.68±0.74) and (1.26±0.69) respectively. Preoperative and postoperative 3, 6 and 12 months of ODI were (63.21±11.21) %, (25.24±6.46) %, (20.97±6.26) % and (17.73±5.88) %, respectively. Postoperative VAS of lumbar and leg pain and ODI were significantly lower than those of preoperative time points (P<0.05). According to the modified MacNab standard, 23 patients got excellent result, 10 good, 3 fair, and 2 poor at 12 months after operation. Postoperative DSCSA, IDH, SR, LL and SL at 12 months were (128.32±21.95) mm², (11.19±1.66) mm, (4.44±2.19)%, (49.32±5.63)°, (9.16±1.90)°, respectively, and were improved compared with preoperative [(58.36±18.11) mm², (8.19±2.06) mm (18.43±4.78) %, (42.38±4.94) ° and (8.06±2.06) °] (P<0.05). Thirty-four patients obtained gradeⅠfusion, 3 patients woth gradⅡfusion and 1 patient with grade Ⅲ fusion at 12 months after operation according to Bridwell intervertebral fusion standard. CONCLUSION PE-PTLIF could provide effective method for the treatment of gradeⅠand gradeⅡdegenerative lumbar spondylolisthesis. It has advantages of less bleeding, sufficient decompression, fast postoperative recovery and high fusion rate, which could effectively relieve lumbar and leg pain, restore vertebral space height and improve lumbar sagittal balance. PE-PTLIF is a safe and minimally invasive surgery.
Humans ; Male ; Female ; Spondylolisthesis/surgery* ; Middle Aged ; Spinal Fusion/methods* ; Lumbar Vertebrae/surgery* ; Aged ; Adult ; Retrospective Studies ; Endoscopy/methods*

Spinal surgical site infection (SSI), especially deep SSI after internal fixation is difficult in treatment, with long course of disease and poor prognosis. At present, there are many controversies in the diagnosis and treatment of spinal SSI, with unsatisfactory overall efficacy of its diagnosis and treatment. Besides, no diagnosis and treatment guideline based on evidence-based medicine has been in existence. To this end, the Spinal Infection Group of the Orthopedic Branch of the Chinese Medical Doctor Association and the Spinal Infection Group of the Spinal Surgery Branch of the Chinese Rehabilitation Medicine Association jointly organized relevant experts to formulate Evidence-based clinical guideline for the diagnosis and treatment of surgical site infection in spinal trauma ( version 2024) based on an evidence-based approach. A total of 10 recommendations were proposed on the diagnosis and treatment of spinal SSI, so as to provide a clinical reference for the diagnosis and treatment of spinal SSI.

Spinal surgical site infection (SSI), especially deep SSI after internal fixation is difficult in treatment, with long course of disease and poor prognosis. At present, there are many controversies in the diagnosis and treatment of spinal SSI, with unsatisfactory overall efficacy of its diagnosis and treatment. Besides, no diagnosis and treatment guideline based on evidence-based medicine has been in existence. To this end, the Spinal Infection Group of the Orthopedic Branch of the Chinese Medical Doctor Association and the Spinal Infection Group of the Spinal Surgery Branch of the Chinese Rehabilitation Medicine Association jointly organized relevant experts to formulate Evidence-based clinical guideline for the diagnosis and treatment of surgical site infection in spinal trauma ( version 2024) based on an evidence-based approach. A total of 10 recommendations were proposed on the diagnosis and treatment of spinal SSI, so as to provide a clinical reference for the diagnosis and treatment of spinal SSI.

Objective: To investigate surgical strategies and the corresponding benefits for patients with perihilar cholangiocarcinoma(pCCA). Methods: A total of 81 patients with pCCA who underwent radical excision in the Department of Biliary and Pancreatic Surgery of Sun Yat-Sen Memorial Hospital between January 2014 and December 2021 were retrospectively collected.The cohort consisted of 50 male and 31 female patients,with an age of (62.5±11.5)years(range:26 to 83 years).Seventy-five cases were diagnosed with jaundice,60 of whom received preoperative biliary drainage,while 20 patients received portal vein embolization.Their serum bilirubin level within one week before the operation(M(IQR)) was 44.3 (41.9) μmol/L(range:8.0 to 344.2 μmol/L).Preoperative imaging examinations were performed to evaluate the Bismuth-Corlette type of pCCA,showing 3,6,21,27,and 24 cases of Bismuth-Corlette type Ⅰ,Ⅱ,Ⅲa,Ⅲb,and Ⅳ,respectively.The primary outcome was overall survival (OS),and the secondary outcomes were relapse-free survival (RFS),90-day postoperative morbidity and 90-day postoperative mortality.OS and RFS were estimated using the Kaplan-Meier method and compared by the Log-rank test.Significant prognostic factors were determined using univariate and multivariable Cox proportional hazard regression analyses. Results: In the cohort of 81 pCCA patients,67 cases(82.7%) underwent major hepatectomy while 3 cases received major hepatectomy combined with pancreaticoduodenectomy.Thirty-four patients underwent hepatectomy combined with vascular resection and reconstruction(18 cases of portal vein resection and reconstruction alone;9 cases of hepatic artery resection and reconstruction alone;7 cases of combination of portal vein and hepatic artery resection and reconstruction).Margin negative(R0 excision) were achieved in 53.1%(43/81) of these patients.The operation duration was (627±136)minutes(range:565 to 940 minutes),and the intraoperative blood loss was 400(455)ml(range:200 to 2 800 ml).The 90-day postoperative mortality was 3.7%(3/81).Grade 3-4 postoperative morbidity was 23.4% (19/81) according to the Clavien-Dindo classification of surgical complications.Up to the last follow-up at September 2022,the follow-up time was 34.0(24.2)months (range:0.4 to 103.6 months).Three patients who died within 90 days after surgery were excluded from the survival analysis.The median OS was 36.10 months (95%CI:18.23 to 42.97 months) and the 1-,3-and 5-year OS rates were 85.3%,46.8% and 27.3%,respectively.The median OS of 41 patients with negative margins was 47.83 months(95%CI:36.90 to 58.80 months) and that of 37 patients with positive margins was 20.47 months(95%CI:10.52 to 30.58 months).The median RFS of 70 patients with R0 and R1 resection was 24.50 months(95%CI:12.15 to 31.85 months)and the 1-,3-and 5-year RFS rates were 65.2%,45.7% and 29.9%,respectively.The median RFS of 41 patients with R0 resection was 38.57 months(95%CI:21.50 to 55.63 months) and that of 29 patients with R1 resection was 10.83 months(95%CI:2.82 to 19.86 months). Conclusions: The primary therapy for pCCA is radical surgical resection.A precise preoperative evaluation and sufficient preparation can reduce postoperative morbidity.Surgical treatment can achieve a better survival outcome by increasing the radical resection rate.

ObjectiveTo observe the effect of Linggui Zhugantang （LG） on the blood-brain barrier （BBB） model of Alzheimer's disease （AD） in vitro and to explore the mechanism of LG in repairing the BBB injury in AD. MethodA total of 50 male SPF rats were randomized into five groups： high-dose （4.8 g·kg^-1）， medium-dose （2.4 g·kg^-1）， and low-dose （1.2 g·kg^-1） LG groups， western medicine （0.5 g·kg^-1 donepezil hydrochloride） group， and normal group （normal saline of equivalent volume）. They received （ig） corresponding drugs twice a day for 7 d. Drug-containing serum was respectively collected from the abdominal aorta 1 h after the last administration. The BBB injury of AD in vitro was induced with the cell co-culture method， and 6 groups were designed： normal group， model group， high-， medium-， and low-dose LG groups， and western medicine group. The model group was added with 100 μL amyloid β_1-42 （Aβ_1-42， final concentration： 5 μmol·L^-1）， and high-dose， medium-dose， and low-dose LG groups and the western medicine group were added with corresponding 10% drug-containing serum in addition to the 100 μL Aβ_1-42 （final concentration： 5 μmol·L^-1）. Cell survival rate was detected by methyl thiazolyl tetrazolium （MTT） assay， expression of BBB-related skeleton proteins （claudin-5， ZO-1， occludin）， matrix metalloproteinase-2 （MMP-2）， and matrix metalloproteinase-9 （MMP-9） by Western blot， and content of inflammatory factors interleukin-1β （IL-1β）， interleukin-6 （IL-6）， and tumor necrosis factor-α （TNF-α） by enzyme-linked immunosorbent assay （ELISA）. BBB Aβ transporter low-density lipoprotein receptor-related protein 1 （LRP-1） and advanced glycation end product receptor （RAGE） at different time points in high-dose， medium-dose， and low-dose LG groups were determined by Real-time PCR and Western blot. ResultCell survival rate of the model group was lower than that of the normal group （P<0.05） and the survival rates of the western medicine group and high-dose LG group was higher than that in the model group （P<0.05）. The skeleton proteins were down-regulated and MMP-2 and MMP-9 were up-regulated in the model group compared with those in the normal group （P<0.05）. The expression of skeleton proteins was higher （P<0.05） and that of MMP-2 and MMP-9 was lower （P<0.05） in the western medicine group and high-dose LG group than in the model group. Compared with the model group， only the medium-dose LG group showed the up-regulation （P<0.05） of claudin-5 （P<0.05） and the decrease （P<0.05） of MMP-2. IL-1β， IL-6， and TNF-α in the model group were up-regulated （P<0.05） compared with those in the normal group， and those inflammatory factors in the western medicine group and high-dose and medium-dose LG groups were lower （P<0.05） than those in the model group. LRP-1 expression was up-regulated and RAGE expression was down-regulated at 3 h compared with those at 0 h （P<0.05）， while the expression of the two became stable at 6， 12， 24， 36 h. At 3 h， LRP-1 expression was down-regulated and RAGE expression was up-regulated in model group compared with those in the normal group at 3 h （P<0.05）. Moreover， the LRP-1 content was higher and RAGE content was lower in the western medicine group and high-dose LG group than in the model group. ConclusionLG can repair the BBB injury in vitro by inhibiting the expression of inflammatory factors and MMP-2， MMP-9， promoting the expression of skeletal proteins， and regulating the balance of transporters.

Objective To evaluate the effects of antiretroviral therapy(ART)for the prevention of mother-to-child transmission(PMTCT)of acquired immune deficiency syndrome(AIDS)on the growth and development of 18-month-old children born by human immunodeficiency virus(HIV)-positive pregnant women in Lingshan County,Guangxi Zhuang Autonomous Region,and provide scientific evidence for improving the ART medication plan for PMTCT.Methods Lingshan County,ranking the first in the HIV-epidemic counties of Guangxi,was selected as the research site.According to the design of retrospective case-control study,we assigned all the subjects into the case group and the control group:(1)The case group included the HIV-positive pregnant women who had received ART for PMTCT and their HIV-negative infants in Lingshan County from 2010 to 2017.The historical cards and PMTCT data of them were collected from the national PMTCT database.(2)The control group included the healthy pregnant women and their healthy babies born in the Lingshan Maternity and Infant Hospital in 2017,and the children's growth and development data were collected.The stunted growth in children was defined as at least one of the three main indicators of body height,body weight,and head circumference below the normal range.Results The number of HIV-positive mothers and their infants in the case group was 391 and 368,respectively,and 87.21%(341/391)and 95.38%(351/368)of mothers and infants respectively received ART medication.The HIV positive rate,mortality rate,and mother-to-child transmission rate of 18-month-old children were 1.36%(5/368),4.35%(16/368),and 2.01%(5/249),respectively.The incidence of stunted growth of 18-month-old children in the case group and the control group was 42.12%(155/368)and 23.06%(101/438),respectively,with significant difference(
Case-Control Studies ; China/epidemiology* ; Female ; Growth and Development ; HIV ; HIV Infections/prevention & control* ; Humans ; Infant ; Infectious Disease Transmission, Vertical/prevention & control* ; Mothers ; Pregnancy ; Pregnancy Complications, Infectious/drug therapy* ; Retrospective Studies

OBJECTIVE: To study the clinical efficacy and complications of Endobutton titanium plate and clavicle hook plate in the treatment of acromioclavicular dislocation. METHODS: Total 48 patients with Rockwood Ⅲ to Ⅴ acromioclavicular joint dislocation from March 2015 to May 2019 were retrospectively divided into two groups according to different surgical methods. Among the patients, 23 patients were treated with Endobutton loop titanium plate fixation (observation group), including 15 males and 8 females, ranging in age from 23 to 59 years old, with an average of(36.2±8.1) years old;Rockwood type Ⅲ in 6 cases, type Ⅳ in 11 cases and type Ⅴ in 6 cases. Twenty-five patients were treated with clavicular hook plate(control group), including 17 males and 8 females, ranging in age from 22 to 54 years old, with an average of (34.7±6.4) years old; Rockwood type Ⅲ in 6 cases, type Ⅳ in 14 cases and type Ⅴ in 5 cases. The operation time, intraoperative bleeding, hospitalization time, visual analogue scale (VAS) of pain, Constant-Murley score of shoulder function and postoperative complications were compared between the two groups. RESULTS: All the patients were followed up, and the duration ranged from 24 to 51 months, with a mean of (30.5±6.5) months. The amountof bleeding and hospitalization time in the observation group were (71.9±4.0) ml and(8.2±1.6) d respectively;and those in the control group were (97.6±13.4) ml and (12.8±1.2) d respectively. There was significant difference between the two groups ( CONCLUSION Compared with clavicular hook plate internal fixation in the treatment of acromioclavicular joint dislocation, Endobutton loop titanium plate internal fixation technology has the advantages of less surgical bleeding, shorter hospitalization time, less postoperative pain, good recovery of shoulder joint function and less complications.
Acromioclavicular Joint/surgery* ; Adult ; Bone Plates ; Case-Control Studies ; Female ; Humans ; Joint Dislocations/surgery* ; Male ; Middle Aged ; Retrospective Studies ; Treatment Outcome ; Young Adult

BACKGROUND: Benvitimod cream, a novel synthetic small molecule, was effective in treating mild-to-moderate plaque psoriasis. We conducted a phase III clinical trial to assess the efficacy and safety of benvitimod cream in patients with mild-to-moderate plaque psoriasis. METHODS: We randomly assigned 686 patients (2:1:1) to receive 1% benvitimod cream, 0.005% calcipotriol ointment or placebo twice a day for 12 weeks. The primary efficacy end points were the percentage of patients with a 75% or greater reduction from baseline in the psoriasis area and severity index (PASI 75) score and with a score of 0 or 1 in static physician's global assessment (sPGA) at week 12. RESULTS: The results showed that 50.4% of patients in the benvitimod group achieved PASI 75, which was significantly higher than that in the calcipotriol (38.5%, P < 0.05) and placebo (13.9%, P < 0.05) groups. The proportion of patients achieving an sPGA score 0 or 1 was 66.3% in the benvitimod group and 63.9% in the calcipotriol group, which were both significantly higher than that in the placebo group (34%, P < 0.05). In the long-term follow-up study, 50.8% of patients experienced recurrence. After retreatment with 1% benvitimod, 73.3% of patients achieved an sPGA score of 0 or 1 again at week 52. Adverse events included application site irritation, follicular papules, and contact dermatitis. No systemic adverse reactions were reported. CONCLUSION: During this 12-week study, benvitimod cream was demonstrated with high effectiveness and safety in patients with mild-to-moderate plaque psoriasis. TRIAL REGISTRATION Chinese Clinical Trial Registry (ChiCTR), ChiCTR-TRC-13003259; http://www.chictr.org.cn/showprojen.aspx?proj=6300.
Double-Blind Method ; Follow-Up Studies ; Humans ; Ointments ; Psoriasis/drug therapy* ; Resorcinols ; Severity of Illness Index ; Stilbenes ; Treatment Outcome

An ideal animal model of azoospermia would be a powerful tool for the evaluation of spermatogonial stem cell (SSC) transplantation. Busulfan has been commonly used to develop such a model, but 30%-87% of mice die when administered an intraperitoneal injection of 40 mg kg^-1. In the present study, hematoxylin and eosin staining, Western blot, immunofluorescence, and quantitative real-time polymerase chain reaction were used to test the effects of busulfan exposure in a mouse model that received two intraperitoneal injections of busulfan at a 3-h interval at different doses (20, 30, and 40 mg kg^-1) on day 36 or a dose of 40 mg kg^-1 at different time points (0, 9, 18, 27, 36, and 63 days). The survival rate of the mice was 100%. When the mice were treated with 40 mg kg^-1 busulfan, dramatic SSC depletion occurred 18 days later and all of the germ cells were cleared by day 36. In addition, the gene expressions of glial cell line-derived neurotrophic factor (GDNF), fibroblast growth factor 2 (FGF2), chemokine (C-X-C Motif) ligand 12 (CXCL12), and colony-stimulating factor 1 (CSF1) were moderately increased by day 36. A 63-day, long-term observation showed the rare restoration of endogenous germ cells in the testes, suggesting that the potential period for SSC transplantation was between day 36 and day 63. Our results demonstrate that the administration of two intraperitoneal injections of busulfan (40 mg kg^-1 in total) at a 3-h interval to mice provided a nonlethal and efficient method for recipient preparation in SSC transplantation and could improve treatments for infertility and the understanding of chemotherapy-induced gonadotoxicity.
Adult Germline Stem Cells/transplantation* ; Animals ; Azoospermia/chemically induced* ; Busulfan/toxicity* ; Disease Models, Animal ; Infertility, Male/chemically induced* ; Injections, Intraperitoneal ; Male ; Mice ; Spermatogenesis/drug effects* ; Spermatogonia/drug effects* ; Stem Cell Transplantation/methods*