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 analyze the disease burden of early-onset colorectal cancer (EOCRC) at the global, regional, and national levels from 1990 to 2021, and to predict the disease burden trend from 2022 to 2026. Methods Based on the Global Burden of Disease (GBD) database, the incidence, mortality, and disability-adjusted life year (DALY) rate of EOCRC across 204 countries and regions from 1990 to 2021 were obtained. The time trends of these indicators were assessed by calculating the estimated annual percentage change (EAPC), and the contributions of ten risk factors to the EOCRC burden were analyzed. The autoregressive integrated moving average (ARIMA) model was used to predict the disease burden from 2022 to 2026. Results From 1990 to 2021, the number of new global EOCRC cases increased from 107 310 to 211 890, with the incidence rising from 3.96 to 5.37 per 100 000 people. In 2021, global EOCRC incidence, mortality, and DALY rate increased with age; males had higher rates than females in terms of incidence, mortality, and DALY rate in all age groups. In 2021, East Asia had the highest number of new cases, deaths, and DALY. From 1990 to 2021, the global EAPC for incidence rate was 0.96%, and death rate was –0.38%. ARIMA model indicated that from 2022 to 2026, the global incidence of EOCRC would continue to rise, while mortality and DALY rate would be expected to decline. Conclusions The disease burden of EOCRC has significantly increased globally from 1990 to 2021, with notable regional, age, and sex differences. By 2026, the mortality and DALY rate of EOCRC will decline, while the incidence is expected to further increase, highlighting the urgency of taking active measures to address the growing trend of EOCRC.

OBJECTIVES: To report the development, validation, and findings of the Multi-dimensional Attention Rating Scale (MARS), a self-report tool crafted to evaluate six-dimension attention levels. METHODS: The MARS was developed based on Classical Test Theory (CTT). Totally 202 highly educated healthy adult participants were recruited for reliability and validity tests. Reliability was measured using Cronbach's alpha and test-retest reliability. Structural validity was explored using principal component analysis. Criterion validity was analyzed by correlating MARS scores with the Toronto Hospital Alertness Test (THAT), the Attentional Control Scale (ACS), and the Attention Network Test (ANT). RESULTS: The MARS comprises 12 items spanning six distinct dimensions of attention: focused attention, sustained attention, shifting attention, selective attention, divided attention, and response inhibition.As assessed by six experts, the content validation index (CVI) was 0.95, the Cronbach's alpha for the MARS was 0.78, and the test-retest reliability was 0.81. Four factors were identified (cumulative variance contribution rate 68.79%). The total score of MARS was correlated positively with THAT (r = 0.60, P < 0.01) and ACS (r = 0.78, P < 0.01) and negatively with ANT's reaction time for alerting (r = -0.31, P = 0.049). CONCLUSIONS The MARS can reliably and validly assess six-dimension attention levels in real-world settings and is expected to be a new tool for assessing multi-dimensional attention impairments in different mental disorders.
Humans ; Adult ; Male ; Attention/physiology* ; Female ; Middle Aged ; Reproducibility of Results ; Young Adult ; Psychometrics

Objective:To explore the clinical and genetic characteristics of two children diagnosed with two rare genetic diseases simultaneously.Methods:Two children with comorbidity of two genetic diseases due to dual genetic mutations diagnosed at the Third Affiliated Hospital of Zhengzhou University respectively in May 2022 and March 2023 were selected as the study subjects. Clinical and genetic data of the two children were retrospectively analyzed. This study has been approved by the Ethics Committee of the Third Affiliated Hospital of Zhengzhou University (Ethic No. 2021-062-01).Results:Child 1 was a 2-year-and-4-month-old boy whose clinical manifestations included facial dysmorphism, developmental delay, short stature, microcephaly, cleft palate, cryptorchidism, hypospadias, recurrent infections and immunological abnormalities. Whole exome sequencing revealed that he had harbored a heterozygous c.6595delT (p.Y2199Ifs*65) variant of the KMT2D gene and a heterozygous c. 1892G>A (p.R631Q) variant of the PIK3R1 gene. This has led to a dual genetic diagnosis of Kabuki syndrome and PI3Kδ-related immunodeficiency type 36. Child 2 was a 15-year-old girl whose clinical manifestations included epilepsy, Albright′s hereditary osteodystrophy, long body trunk, short limbs, hypocalcemia, hyperphosphatemia and hyperparathyroidism. The child also had a family history of short stature. Whole exome sequencing revealed that she had harbored a heterozygous c. 2T>C (p.Met1? ) variant of the GNAS gene and deletion of exons 2 to 6 of the SHOX gene. The two variants have led to dual diagnose of pseudohypoparathyroidism and X-linked idiopathic short stature. Conclusion:When the clinical phenotype of a genetic disease is complex and cannot be fully explained with a single genetic variant, multiple pathogenic variants should be considered, and this may lead to the diagnosis of co-morbid genetic diseases. To adopt or supplement corresponding genetic testing in time and re-analyze the genetic data may facilitate accurate diagnosis of comorbid genetic diseases.

Objective:To investigate the prevalence of baseline dyslipidemia in HIV-infected people before starting antiviral therapy (ART) in China.Methods:The data were collected from HIV/AIDS ART database of Chinese Disease Prevention and Control Information System. A national sample of HIV- infected people who initiated ART from 2018 to 2023 was used to collect baseline information, including sociodemographic characteristics and laboratory test results. According to the Chinese Lipid Management Guidelines (2023) and the National Cholesterol Education Program Adult Treatment Panel Ⅲ guidelines, triglyceride (TG) ≥1.7 mmol/L or total cholesterol (TC) ≥5.2 mmol/L were identified as dyslipidemia. Statistical analysis was performed with software SAS 9.4. An unconditional logistic regression model was used to analyze the factors influencing TG and TC abnormalities in HIV-infected patients before ART.Results:A total of 359 952 adults infected with HIV were included in this study, the prevalence rate of dyslipidemia was 38.41% (138 263/359 952). The abnormal rates of TG and TC were 31.40% (113 041/359 952) and 13.75% (49 494/359 952), respectively. In all age groups except for the 25-44 age groups, the abnormal rates of TG and TC were higher in HIV-infected women than in HIV-infected men. In HIV-infected patients, women, those aged 45-64 years, those lived in northeast region, those had heterosexual transmission, and those with BMI ≥28.0 kg/m 2, CD4 +T lymphocytes counts ≥500 cells/μl had higher rates of baseline dyslipidemia (all P<0.05). Conclusions:The abnormal rate of TG in HIV-infected people before ART was higher in China from 2018 to 2023, especially in HIV-infected women, and the abnormal rate of TG and TC increased with age. Attention should be paid to the clinical diagnosis and ART selection in the treatment of HIV infection.

Objective In this study,we investigated the correlation between the scores for different Liebowitz Social Anxiety Scale(LSAS)subscale models and the metabolic activity in specific regions of the brain using 18F-fluorodeoxyglucose(FDG)positron emission tomography/computed tomography(PET/CT)(18F-FDG PET),thereby improving the understanding of the neurobiological characteristics of social anxiety.Methods A total of 39 cognitively normal participants(29 men and 10 women,aged 30-63 years)were enrolled.All participants underwent LSAS assessment and brain 18F-FDG PET scanning.Correlations between metabolic activities in various brain regions and scores from the different LSAS subscales were analyzed accordingly.Results LSAS subscale scores were significantly correlated with metabolic activity in specific brain regions.In the Safren model,the score for the observation by others subscale was positively correlated with the left fusiform gyrus(P<0.001,false discovery rate[FDR]-corrected)and the left caudate tail(P<0.001,FDR-corrected),suggesting a close association between mood states related to observation by others and the metabolic activity in these regions.In the Baker model,the score for the eating and drinking subscale was negatively correlated with the right precuneus(P<0.001,FDR-corrected),while the score for the assertiveness subscale was positively correlated with the left caudate nucleus(P<0.001,FDR-corrected).These findings revealed the complex associative patterns between various mood and behavioral dimensions and metabolic activities in specific brain regions.Conclusion Social anxiety symptoms are closely associated with metabolic changes in specific brain regions,including the left insula,left caudate tail,and right precuneus.Moreover,different social situations activate distinct brain regions.Compared with individuals with social anxiety disorder,normal individuals exhibit involvement of fewer brain regions when experiencing social anxiety.These findings provide new experimental evidence for understanding the neural mechanisms underlying social anxiety.

Objective:To explore the short-term clinical effects of deep cervical lymph node-venous anastomosis in the treatment of Alzheimer’s disease (AD).Methods:A prospective exploratory study was conducted on the treatment of AD patients using the cervical deep lymph node-venous anastomosis technique in Scar and Wound Treatment Department, Plastic Surgery Hospital, Chinese Academy of Medical Sciences, from September to October 2024. The patients underwent high-frequency ultrasound to locate deep cervical lymph nodes and the external jugular vein. Under general anesthesia, bilateral deep cervical lymph node-venous anastomoses were performed. Indocyanine green (ICG) lymphography was conducted via subcutaneous injection behind the ear to visualize lymph nodes in levels Ⅱ and Ⅲ. After making a skin incision along the posterior margin of the sternocleidomastoid muscle, the external jugular vein, internal jugular veins, and associated lymph nodes were exposed. Adjacent veins were selected for anastomosis of lymph node. Using microsurgical techniques, end-to-side or end-to-end anastomosis was completed for lymph nodes in levels Ⅱ and Ⅲ. Preoperative assessments included the mini-mental state examination (MMSE, a higher score indicates better cognitive function), Alzheimer’s disease assessment scale-cognitive subscale (ADAS-Cog, a higher score indicates greater impairment of cognitive function), Alzheimer’s disease cooperative study scale for activities of daily living (ADCS-ADL, a higher score indicates better ability to perform daily activity), and neuropsychiatric inventory (NPI, a higher score indicates more severe behavioral and emotional symptom). Postoperative follow-up included the same scales to observe changes in cognitive function, activities of daily living, and emotional communication.Results:Four patients (1 male, 3 females, aged 58-79 years) with AD were included. All were diagnosed based on cerebrospinal fluid biomarkers. All patients successfully underwent bilateral deep cervical lymph node-venous anastomoses. On average, 4.3 (2-7 per person) anastomoses were performed per patient. Surgical procedures lasted an average of 6.5 h (5.5-8.5 h) with minimal blood loss (less than 50 ml). Patients resumed normal activity within 6 hours postoperatively and were discharged after an average of 4.1 d (3.5-5.0 d). Postoperative complications included one case each of aspiration pneumonia, lower limb venous thrombosis, and transient delirium, all of whom resolved without long-term effects. Clinical symptoms, including memory decline, mood swings, and anxiety, showed varying degrees of improvement. Patients reported enhanced quality of life, emotional stability, and social engagement, confirming the procedure’s safety and potential cognitive benefits. At one month postoperatively, the MMSE scores of the four patients increased by an average of 0.8 points compared to preoperative levels. Additionally, the two patients who completed the ADAS-Cog assessments showed a decrease in their scores (reduced by 1.0 points and 11.3 points, respectively, compared to preoperative scores), indicating a certain degree of improvement in cognitive function during this period. The ADCS-ADL and NPI scores of four patients varied significantly, without showing any clear pattern.Conclusion:Lymphovenous anastomosis of the deep cervical lymph node-venous anastomosis may provide a new surgical intervention approach for AD, but further large-scale studies and long-term follow-up are needed to validate its safety and effectiveness.

Objective:To explore the causal relationship between human immune cell phenotypes and keloids.Methods:This study was based on a two-sample Mendelian randomization (MR) analysis. Human immune cell phenotypes were considered as the exposure factors, and keloid was the outcome. Data on immune cell phenotypes (3 757 samples) and keloids (668 samples) were obtained from the genome-wide association study database. Using single nucleotide polymorphisms (SNPs) significantly associated with immune cell phenotypes as instrumental variables with the influence of weak instrumental variables being excluded, two-sample MR analysis was employed to evaluate the causal relationship between 731 human immune cell phenotypes and keloids. The inverse variance weighted (IVW) method was used to infer causal relationships, and the MR-Egger, weighted median, and weighted mode methods were used for validation. For SNPs of immune cell phenotypes meeting the hypothesis, the Cochran Q test was used to assess heterogeneity, and the MR-Egger regression and MR-PRESSO outlier tests were used to evaluate horizontal pleiotropy.Results:A total of 18 204 SNPs meeting the significant threshold ( P<1×10??) were selected as instrumental variables for 731 immune cell phenotypes, and none of these SNPs were weak instrumental variables (with F values all >10). According to the IVW method, 21 immune cell phenotypes were identified with potential causal relationships to keloids, among which the CD62L - monocyte absolute count, CD19 on naive-mature B cell, CD19 on IgD + B cell, CD27 on plasma blast-plasma cell, CD86 on CD62L + myeloid dendritic cell, CD45 on natural killer T cell, CD25 on CD39 + CD4 + regulatory T cell, CD45 on monocytic myeloid-derived suppressor cells, CD8 on effector memory CD8 + T cell, and CD45RA on resting CD4 + regulatory T cell showed significant positive correlations with keloids (with odds ratios of 1.12, 1.09, 1.08, 1.21, 1.13, 1.12, 1.17, 1.11, 1.10, and 1.07, respectively, 95% confidence intervals of 1.03-1.23, 1.02-1.16, 1.01-1.15, 1.06-1.38, 1.02-1.25, 1.01-1.24, 1.03-1.33, 1.00-1.23, 1.00-1.20, and 1.01-1.13, respectively, P<0.05), while the activated and secreted CD4 + regulatory T cell absolute count, CD25 on unswitched memory B cell, plasmacytoid dendritic cell absolute count, CD14 on monocytic myeloid-derived suppressor cells, CD8 on natural killer T cell, CD20 on IgD + CD38 + B cell, CD11c + CD62L - monocyte absolute count, CD66b ++ myeloid cell absolute count, CD11c on granulocytes, CD14 on CD14 + CD16 + monocyte, and CD3 on central memory CD8 + T cell showed significant negative correlations with keloids (with odds ratios of 0.95, 0.93, 0.93, 0.93, 0.91, 0.89, 0.89, 0.88, 0.87, 0.86, and 0.85, respectively, 95% confidence intervals of 0.90-1.00, 0.87-0.99, 0.88-0.99, 0.87-0.99, 0.84-1.00, 0.81-0.98, 0.81-0.98, 0.79-0.99, 0.78-0.96, 0.75-0.99, and 0.74-0.96, respectively, P<0.05). MR-Egger method confirmed the potential causal relationship existing respectively between CD25 on CD39 + CD4 + regulatory T cell, CD86 on CD62L + myeloid dendritic cell, CD19 on IgD + B cell, CD45RA on resting CD4 + regulatory T cell, CD3 on central memory CD8 + T cell and keloids (with odds ratios of 1.32, 1.22, 1.11, 1.09, and 0.73, respectively, 95% confidence intervals of 1.03-1.70, 1.04-1.44, 1.02-1.21, 1.01-1.19, and 0.55-0.95, respectively, P<0.05). The weighted median method confirmed the potential causal relationship existing respectively between CD45 on natural killer T cell, activated and secreted CD4 + regulatory T cells absolute count, CD20 on IgD + CD38 + B cell, CD66b ++ myeloid cell absolute count and keloids (with odds ratios of 1.15, 0.93, 0.87, and 0.83, respectively, 95% confidence intervals of 1.01-1.31, 0.86-1.00, 0.77-0.98, and 0.71-0.96, respectively, P<0.05). Among them, the potential causal relationship between CD20 on IgD + CD38 + B cell and keloids was further verified by the weighted mode method (with odds ratio of 0.86, 95% confidence interval of 0.77-0.97, P<0.05). According to the aforementioned IVW method analysis results, the SNPs associated with the 21 immune cell phenotypes that had a significant causal relationship with keloids showed no significant heterogeneity ( P>0.05) or significant horizontal pleiotropy ( P>0.05). Conclusions:From a genetic perspective, the potential causal relationships between 21 human immune cell phenotypes and keloids have been revealed, of which 10 immune cell phenotypes may be risk factors for keloids, while 11 immune cell phenotypes may act as protective factors for keloids.

Objective:To investigate the clinical effect of indocyanine green angiography (ICGA)-assisted design and harvest of expanded flaps for scar reconstruction.Methods:This study was a retrospective observational study. From April 2019 to August 2023, 19 patients with scars (8 males, 11 females; aged 3-38 years) treated at the Plastic Surgery Hospital of Peking Union Medical College and Chinese Academy of Medical Sciences met the inclusion criteria. The scars were distributed on the head, face, trunk, and extremities. In stage Ⅰ surgery, skin soft tissue expanders were implanted in suitable areas around the scars for skin soft tissue expansion. In stage Ⅱ surgery, the scar tissue was excised, resulting in wound areas ranging from 100 to 210 cm 2, and expanded flaps were designed. ICGA was used to identify target perforators and their accompanying veins, and the flap design was adjusted to ensure the inclusion of complete arterial and venous axes. The expanded flap with an area of 120 to 240 cm2 was harvested using unilateral back-cut technique and transferred to the recipient site, and the donor site wound was sutured directly. The durations of the arterial and venous phases of ICGA during flap design were recorded. The length-to-width ratios of the back-cut flaps were calculated for different regions. After stage Ⅱ surgery, the blood perfusion and survival of the flap, the wound healing at the donor site, and the occurrence of complications were observed. During follow-up, the appearance, color, and texture of the patient's flap were observed. Results:The arterial phase of ICGA lasted 10-27 (18±5) s, and the venous phase lasted 78-116 (100±10) s. The length-to-width ratios of the back-cut flaps were 1.22±0.32, 1.63±0.12, and 1.15±0.21 for the head and neck, trunk, and limb regions, respectively. After stage Ⅱ surgery, one patient had a large area of insufficient blood perfusion in the flap. By comparing ICGA images before and after flap transfer, the sutures at the oral commissure were loosened, the blood flow of the flap was restored. The blood perfusion of the flaps in other patients was good. All flaps survived completely, with well-healed donor site wounds and no complications. During 0.5-14.0 months of follow-up, all flaps of patients demonstrated excellent appearance, with color and texture matching the surrounding skin.Conclusions:As a means of superficial blood flow visualization, ICGA can not only clearly show the microvascular distribution of the expanded flap before operation, assist in optimizing the design of the flap, but also evaluate the blood perfusion of the flap after operation, reduce the occurrence of complications, and provide a full-process navigation for the harvesting of expanded flaps, thereby improving the safety of flap transfer for scar reconstruction.

The advantages of few-shot learning in arrhythmia detection were introduced.The research progress of few-shot learning strategies,including metric learning,transfer learning and data augmentation,was reviewed when applied to arrhythmia detection.The limitations of few-shot learning in arrhythmia detection were analyzed.It was pointed out that the graph neural network and new incremental learning techniques would be involved in the future development of few-shot learning in arrhythmia detection.[Chinese Medical Equipment Journal,2025,46(8):104-112]