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 compare the efficacy and safety of sodium zirconium cyclosilicate and calcium polystyrene sulphonate in the treatment of hyperkalemia in chronic kidney disease(CKD).Methods Hospitalized patients with CKD hyperkalemia admitted to Qingyuan People's Hospital from January 2022 to November 2023 were retrospectively selected as study objects,and were divided into sodium zirconium cyclosilicate group and calcium polystyrene sulphonate group according to different drug use.The two groups of patients were matched with 1:1 propensity score,and finally 43 pairs of data were successfully matched.The efficacy and incidence of adverse reactions were compared between two groups of patients after matching.Results After treatment,the serum potassium level in both groups was significantly lower than that before treatment(P<0.05),but there was no significant difference in serum potassium level between two groups(P>0.05).There was no significant difference in the total effective rate between two groups(χ2=1.242,P=0.537).After treatment,the blood sodium level in sodium zirconium cyclosilicate group was significantly higher than that before treatment(P<0.05),there was no significant difference in blood calcium level before and after treatment(P>0.05).There was no significant difference in serum sodium and serum calcium before and after treatment in calcium polystyrene sulphonate group(P>0.05).There was one patient with hypokalemia in each group,and no treatment related adverse reactions such as nausea,edema,constipation,abdominal bloating and diarrhea were observed,and no abnormal laboratory test results were found.Conclusion The clinical efficacy of sodium zirconium cyclosilicate and calcium polystyrene sulphonate in treatment of hyperkalemia in CKD patients is comparable,and the safety is good.

Objective:To investigate whether intermittent fasting alleviates insulin resistance in a polycystic ovary syndrome(PCOS) mouse model through the regulation of autophagy.Methods:Fifty 3-week-old female C57BL/6J mice were randomly assigned into the following groups using a random number table: normal control(NC) group( n=10), maintained on a standard chow diet; high-fat diet(HFD) group( n=10) fed a diet with 60% of calories derived from fat; and PCOS model group( n=30), established by combining a HFD with dehydroepiandrosterone(DHEA) administration. Successful modeling was confirmed by disrupted estrous cycles, hyperandrogenism, and polycystic ovarian morphology. The PCOS model mice were further divided into three groups: PCOS group( n=9), PCOS with intermittent fasting group(PCOS+ IF, n=9), and PCOS with intermittent fasting plus the autophagy inhibitor 3-methyladenine(3-MA) group(PCOS+ IF+ 3-MA, n=9). Autophagy levels were assessed by detecting markers LC3 and p62 and observing autophagosomes via transmission electron microscopy. Glucose tolerance test(GTT) and insulin tolerance test(ITT) were performed, and the area under the curve(AUC) was calculated to evaluate insulin resistance. Western blotting was used to detect phosphorylation levels of phosphatidylinositol 3-kinase(PI3K), protein kinase B(Akt), mammalian target of rapamycin(mTOR), and p70S6 kiase(p70S6K). Results:Compared with the NC group, the PCOS model group showed absent estrous cycles, significantly elevated serum testosterone, sex hormone binding globulin, and luteinizing hormone(LH) levels( P<0.001), and polycystic ovarian changes on hematoxylin-eosin staining, confirming successful model establishment. Immunohistochemistry, transmission electron microscopy, and Western blotting demonstrated that autophagy levels were increased in the PCOS+ IF group compared with the PCOS group, while 3-MA administration reduced the intermittent fasting - induced autophagy. The AUC values for both GTT and ITT were significantly lower in the PCOS+ IF group than those in the PCOS group( P<0.001, P=0.003), but increased in the PCOS+ IF+ 3-MA group compared to the PCOS+ IF group( P<0.001, P=0.020). Western blotting analysis showed that phosphorylation levels of PI3K, Akt, mTOR, and p70S6K were significantly decreased in the PCOS+ IF group compared with the PCOS group( P=0.002, P=0.001, P=0.001, and P<0.001, respectively), and increased in the PCOS+ IF+ 3-MA group compared with the PCOS+ IF group( P=0.021, P=0.041, P=0.047, and P=0.024, respectively). Conclusions:Intermittent fasting alleviates insulin resistance in a PCOS mouse model through inhibitiing PI3K/Akt/mTOR signaling pathway and promoting autophagy.

Objective To explore the factors influencing cognitive frailty in elderly inpatients with chronic heart failure(CHF)during hospitalisation,8 prediction models were developed with various machine learning algorithms to identify the best model as a guidance for medical staff on clinical interventions.Methods Convenience sampling method was used to select 650 elderly CHF inpatients who stayed in our hospital between September 2023 and June 2024 as the study objects in the cross-sectional investigation.A total of 607 patients had completed the study.The patients were divided into a cognitive frailty group and a non-cognitive frailty group according to the presence or absence of cognitive frailty.Variables were initially screened using univariate analysis and stepwise Logistic regression.The total sample was then randomly divided into a training set(n=424)and a testing set(n=183)of a 7:3 ratio.Eight predictive models were created using the algorithms of neural network(NN),k-nearest neighbour(KNN),linear discriminant analysis(LDA),support vector machine(SVM),naive Bayes(NB),logistic regression,decision tree(DT)and random forest(RF)on the training set.The predictive performance of the models was compared using the data of the testing set.Results The prevalence of cognitive frailty in elderly CHF inpatients was 48.3%.Results of Logistic regression showed that age,marital status,education,body mass index,multi-morbidity,nutritional status,medication,frequency of weekly exercise and the living conditions were the key factors(P<0.05).The overall accuracy in classification of the eight predictive models ranged from 0.803 to 0.847,with F1-values of 0.778 to 0.833,precision of 0.848 to 0.897,and recall rate of 0.700 to 0.778.The area under the receiver operating characteristic curve was 0.820 to 0.901.Conclusion Of the eight predictive models,the prediction model created with LDA shows the best performance and prediction in terms of comprehensive prediction metrics,while the prediction model created with NN shows the worst performance in comprehensive prediction.

AIM To explore the relieving effect of Er Miao Wan on atopic dermatitis in mice.METHODS In vivo experiment:BALB/c mice were randomly divided into normal group,model group,dexamethasone group(2 mg/kg)and high,medium and low dose groups of Er Miao Wan(4.68,2.34 and 1.17 g/kg).The mouse model of atopic dermatitis was established by repeatedly smearing DNCB solution,and the model was given orally for 21 days.The skin lesion condition on the back of mice,ear swelling degree,and the weight difference between ear lobes were observed and recorded.HE staining was used to observe the histopathological changes in the skin lesion tissues of mice.Toluidine blue(TB)staining was used to observe the infiltration of mast cells in skin lesions.The expression of macrophage marker F4/80 in skin lesions was detected by IHC.The serum levels of TSLP,IL-4,IL-5 and total IgE were detected by ELISA.In vitro experiment:RAW264.7 cells in logarithmic growth period were given 400,200 and 100 μg/mL Er Miao Wan for intervention.Cell proliferation was detected by CCK-8 method.NO level in cell supernatant was detected by Griess method.TNF-α,IL-1 β and IL-6 levels in cell supernatant were detected by ELISA method.The expressions of proteins related to the MAPK/NF-κB signaling pathway in cells was detected by Western blot.RESULTS In vivo experiment:Compared with the model group,the scores of back skin lesions,the swelling degree of right ear and the weight difference between left and right ear pieces in the high-dose group of Er Miao Wan decreased(P＜0.05,P＜0.01),the thickness of skin lesions decreased,the infiltration of mast cells and macrophages decreased(P＜0.05,P＜0.01),and the inflammatory factors TSLP,IL-4,IL-5 and total IgE levels in serum decreased(P＜0.05,P＜0.01),and the expression of F4/80 in the skin lesions decreased(P＜0.01).In vitro experiment:Compared with the model group,the levels of NO,TNF-α,IL-1 β and IL-6 in Er Miao Wan 400 and 200 μg/mL groups decreased(P＜0.05,P＜0.01),and the phosphorylation levels of P38,JNK and P65 proteins decreased(P＜0.05,P＜0.01).CONCLUSION Er Miao Wan can alleviate skin lesion inflammation in DNCB-induced atopic dermatitis mice,and its mechanism may be related to inhibiting the activation of MAPK/NF-κB signaling pathway of macrophage,reducing macrophage infiltration and reducing Th2 cytokines.

Objective:To investigate the changes in and correlations between melanin-concentrating hormone (MCH) and androgen levels in the serum of patients with polycystic ovary syndrome (PCOS), aiming to provide a novel research perspective for its diagnosis.Methods:A cross-sectional study. A total of 307 subjects were enrolled from the physical examination center and endocrinology clinic of the Affiliated Hospital of Zunyi Medical University from June 2023 to June 2024. The cohort comprised 114 healthy controls and 193 patients with PCOS, diagnosed according to the Rotterdam criteria. The patients were grouped into four phenotypes: Phenotype A (hyperandrogenemia [HA]+ovulatory dysfunction [OA]+polycystic ovarian morphology [PCOM], n=44), Phenotype B (HA+OA, n=50), Phenotype C (HA+PCOM, n=46), and Phenotype D (OA+PCOM, n=53). Clinical data were collected for all subjects. Serum MCH levels were determined by enzyme-linked immunosorbent assay. The relationship between MCH and androgen-related risk factors for PCOS was analyzed using Spearman partial correlation analysis and stepwise multiple linear hierarchical regression. Binary logistic regression was used to analyze factors influencing PCOS onset. The diagnostic value of MCH for PCOS was evaluated using a receiver operating characteristic (ROC) curve. Results:There were no significant differences in age and height between the healthy control group and the PCOS phenotypic groups (both P>0.05). MCH levels [17.63 (12.69, 22.00), 17.31 (11.05, 20.09), 17.82 (11.47, 19.40), 16.50 (11.14, 19.41) μg/L vs. 12.14 (9.78, 15.05) μg/L], homeostatic model assessment of insulin resistance, fasting plasma glucose, fasting serum lisulin, body mass index, and weight were significantly higher across all four PCOS phenotypes (A, B, C, and D) than in healthy controls (all P<0.05), whereas sex hormone-binding globulin (SHBG) contents were significantly lower ( P<0.05). Free androgen index (FAI), total testosterone (TES) and dehydroepiandrosterone (DHEA) levels were significantly higher in PCOS phenotypes A, B, and C than in the control group and PCOS phenotype D (all P<0.05). Spearman partial correlation analysis revealed no significant correlation between MCH and TES, DHEA, or FAI in healthy controls and patients with non-HA PCOS (all P>0.05). However, in PCOS patients with HA, MCH showed a significant positive correlation with TES and DHEA ( r=0.227 and 0.196, respectively; both P<0.05), but not FAI ( P>0.05). Stepwise multiple linear hierarchical regression analysis showed that MCH was positively correlated with TES, DHEA and luteinizing hormone and negatively correlated with SHBG (all P<0.05). Binary logistic regression indicated that an increase in MCH may be a potential risk factor for PCOS occurrence ( OR=1.113, 95% CI 1.012-1.224, P=0.028). ROC analysis showed that MCH has diagnostic value for PCOS ( P<0.05), with an area under the curve of 0.713. Conclusion:Serum MCH is closely related to FAI, TES, and DHEA levels in PCOS patients and may play an important role in the etiology and progression of the syndrome.

Objective:To explore the safety, effectiveness, and short-term outcomes of transoral robotic surgery (TORS) for supraglottic laryngeal cancer.Methods:A retrospective analysis was conducted on patients with supraglottic laryngeal cancer who underwent TORS at Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Tongji Hospital of Tongji Medical College of Huazhong University of Science and Technology, Eye Ear Nose and Throat Hospital of Fudan University, and the First Affiliated Hospital of China Medical University between January 2018 and April 2024. Data on operative time, intraoperative blood loss, postoperative hospital stay, perioperative tracheostomy, nasogastric feeding, complications, and short-term follow-up were analyzed. Statistical analysis was performed using Python.Results:A total of 27 patients with supraglottic laryngeal cancer were included from the four centers, including 24 males and 3 females, with a median age of 66 (65, 68) years [ M( Q1, Q3), same below]. There were 26 cases of squamous cell carcinoma and 1 case of adenoid cystic carcinoma.The TNM staging included T1 in 10 cases (37.04%), T2 in 13 cases (48.15%), and T3 in 4 cases (14.81%); N0 in 14 cases (51.85%), N1 in 7 cases (25.93%), and N2 in 6 cases (22.22%). The Da Vinci Si system was used in 23 cases, and the Da Vinci Xi in 4 cases. The robotic surgical time was 53 (30, 58) min. Concurrent neck dissection was performed in 25 cases, neoadjuvant therapy was given preoperatively in 8 cases (29.63%), and postoperative radiotherapy was administered in 13 cases (48.15%). Tracheostomy was performed in 11 cases (40.74%). Nasogastric tube placement was required in 23 cases (85.19%), with a median duration of 16 (12, 21) days. The postoperative hospital stay was 9.19±4.07 days. The median follow-up time was 12 (3, 30) months. Local recurrence occurred in 2 cases. The 3-year overall survival rate was 100%, and the 3-year disease-free survival rate was 94.1%. Conclusion:With appropriate patient selection, TORS for supraglottic laryngeal cancer demonstrates satisfactory short-term outcomes, thereby offering advantages in safety, efficacy, and minimal invasiveness, which can be considered a new treatment option for this condition.

ObjectiveIn nature, objects cast shadows due to illumination, forming the basis for stereoscopic perception. Birds need to adapt to changes in lighting (meaning they can recognize stereoscopic shapes even when shadows look different) to accurately perceive different three-dimensional forms. However, how neurons in the key visual brain area in birds handle these lighting changes remains largely unreported. In this study, pigeons (Columba livia) were used as subjects to investigate how neurons in pigeon’s ventrolateral mesopallium (MVL) represent stereoscopic shapes consistently, regardless of changes in lighting. MethodsVisual cognitive training combined with neuronal recording was employed. Pigeons were first trained to discriminate different stereoscopic shapes (concave/convex). We then tested whether and how light luminance angle and surface appearance of the stereoscopic shapes affect their recognition accuracy, and further verify whether the results rely on specify luminance color. Simultaneously, neuronal firing activity of neurons was recorded with multiple electrode array implanted from the MVL during the presentation of difference shapes. The response was finally analyzed how selectively they responded to different stereoscopic shapes and whether their selectivity was affected by the changes of luminance condition (like lighting angle) or surface look. Support vector machine (SVM) models were trained on neuronal population responses recorded under one condition (light luminance angle of 45°) and used to decode responses under other conditions (light luminance angle of 135°, 225°, 315°) to verify the invariance of responses to different luminance conditions. ResultsBehavioral results from 6 pigeons consistently showed that the pigeons could reliably identify the core 3D shape (over 80% accuracy), and this ability wasn’t affected by changes in light angle or surface appearance. Statistical analysis of 88 recorded neurons from 6 pigeons revealed that 83% (73/88) showed strong selectivity for specific 3D shapes (selectivity index>0.3), and responses to convex shapes were consistently stronger than to concave shapes. These shape-selective responses remained stable across changes in light angle and surface appearance. Neural patterns were consistent under both blue and orange lighting. The decoding accuracy achieves above 70%, suggesting stable responses under different conditions (e.g., different lighting angles or surface appearance). ConclusionNeurons in the pigeon MVL maintain a consistent neural encoding pattern for different stereoscopic shapes, unaffected by illumination or surface appearance. This ensures stable object recognition by pigeons in changing visual environments. Our findings provide new physiological evidence for understanding how birds achieve stable perception (“invariant neural representations”) while coping with variations in the visual field.

BACKGROUND: While emotional distress, encompassing anxiety and depression, has been associated with negative clinical outcomes, its impact across various clinical departments and general hospitals has been less explored. Previous studies with limited sample sizes have examined the effectiveness of specific treatments (e.g., antidepressants) rather than a systemic management strategy for outcome improvement in non-psychiatric inpatients. To enhance the understanding of the importance of addressing mental health care needs among non-psychiatric patients in general hospitals, this study retrospectively investigated the impacts of emotional distress and the effects of early detection and management of depression and anxiety on hospital length of stay (LOS) and rate of long LOS (LLOS, i.e., LOS >30 days) in a large sample of non-psychiatric inpatients. METHODS: This retrospective cohort study included 487,871 inpatients from 20 non-psychiatric departments of a general hospital. They were divided, according to whether they underwent a novel strategy to manage emotional distress which deployed the Huaxi Emotional Distress Index (HEI) for brief screening with grading psychological services (BS-GPS), into BS-GPS ( n = 178,883) and non-BS-GPS ( n = 308,988) cohorts. The LOS and rate of LLOS between the BS-GPS and non-BS-GPS cohorts and between subcohorts with and without clinically significant anxiety and/or depression (CSAD, i.e., HEI score ≥11 on admission to the hospital) in the BS-GPS cohort were compared using univariable analyses, multilevel analyses, and/or propensity score-matched analyses, respectively. RESULTS: The detection rate of CSAD in the BS-GPS cohort varied from 2.64% (95% confidence interval [CI]: 2.49%-2.81%) to 20.50% (95% CI: 19.43%-21.62%) across the 20 departments, with a average rate of 5.36%. Significant differences were observed in both the LOS and LLOS rates between the subcohorts with CSAD (12.7 days, 535/9590) and without CSAD (9.5 days, 3800/169,293) and between the BS-GPS (9.6 days, 4335/178,883) and non-BS-GPS (10.8 days, 11,483/308,988) cohorts. These differences remained significant after controlling for confounders using propensity score-matched comparisons. A multilevel analysis indicated that BS-GPS was negatively associated with both LOS and LLOS after controlling for sociodemographics and the departments of patient discharge and remained negatively associated with LLOS after controlling additionally for the year of patient discharge. CONCLUSION Emotional distress significantly prolonged the LOS and increased the LLOS of non-psychiatric inpatients across most departments and general hospitals. These impacts were moderated by the implementation of BS-GPS. Thus, BS-GPS has the potential as an effective, resource-saving strategy for enhancing mental health care and optimizing medical resources in general hospitals.
Humans ; Retrospective Studies ; Male ; Length of Stay/statistics & numerical data* ; Female ; Middle Aged ; Adult ; Psychological Distress ; Inpatients/psychology* ; Aged ; Anxiety/diagnosis* ; Depression/diagnosis*

BACKGROUND: Early control of low-density lipoprotein cholesterol (LDL-C) is crucial for reducing the progress of cardiovascular disease. However, its additional role to the risk of primary osteoporosis in men with coronary heart disease was inconclusive. Our study aims to determine the association of LDL-C and its trajectories for osteoporosis risk in the middle-aged and aged men of China. METHODS: The retrospective cohort study of 1546 men aged 69.74 ± 11.30 years conducted in Beijing, China from 2015 to 2022. And the incidence of primary osteoporosis was annually recorded. LDL-C trajectories were further identified by latent class growth model using repeated measurements of LDL-C. The association of baseline LDL-C for osteoporosis was estimated using hazard ratio (HR) with 95% CI in Cox proportional hazard model, while mean level and trajectories of LDL-C for osteoporosis were evaluated using odds ratio (OR) with 95% CI in logistic regression model. RESULTS: During the median 6.2-year follow-up period, 70 men developed primary osteoporosis. The higher level of baseline LDL-C (HR = 1.539, 95% CI: 1.012-2.342) and mean LDL-C (OR = 2.190, 95% CI: 1.443-3.324) were associated with higher risk of osteoporosis in men with coronary heart disease after adjusted for covariates. Compared with those in the LDL-C trajectory of low-stable decrease, participants with medium-fluctuant trajectory, whose longitudinal LDL-C started with a medium LDL-C level and appeared an increase and then decrease, were negatively associated with osteoporosis risk (OR = 2.451, 95% CI: 1.152-5.216). And participants with initially high LDL-C level and then a rapid decrease demonstrated a tendency towards reduced risk (OR = 0.718, 95% CI: 0.212-2.437). CONCLUSIONS Elevated LDL-C level and its long-term fluctuation may increase the risk of primary osteoporosis in men. Early controlling a stable level of LDL-C is also essential for bone health.