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.

Aiming at the problems of missing important features, inconspicuous details and unclear textures in the fusion of multimodal medical images, this paper proposes a method of computed tomography (CT) image and magnetic resonance imaging (MRI) image fusion using generative adversarial network (GAN) and convolutional neural network (CNN) under image enhancement. The generator aimed at high-frequency feature images and used double discriminators to target the fusion images after inverse transform; Then high-frequency feature images were fused by trained GAN model, and low-frequency feature images were fused by CNN pre-training model based on transfer learning. Experimental results showed that, compared with the current advanced fusion algorithm, the proposed method had more abundant texture details and clearer contour edge information in subjective representation. In the evaluation of objective indicators, Q ^AB/F, information entropy (IE), spatial frequency (SF), structural similarity (SSIM), mutual information (MI) and visual information fidelity for fusion (VIFF) were 2.0%, 6.3%, 7.0%, 5.5%, 9.0% and 3.3% higher than the best test results, respectively. The fused image can be effectively applied to medical diagnosis to further improve the diagnostic efficiency.
Image Processing, Computer-Assisted/methods* ; Neural Networks, Computer ; Tomography, X-Ray Computed ; Magnetic Resonance Imaging/methods* ; Algorithms

Objective To analyze the epidemiological characteristics of hepatitis A in Guangxi from 2010 to 2020, and to provide a scientific basis for formulating effective prevention and control strategies. Methods Descriptive epidemiological method was used to analyze the incidence data of hepatitis A in Guangxi from 2010 to 2020. Results From 2010 to 2020, a total of 8,742 cases of hepatitis A were reported in Guangxi, with an average annual incidence rate of 1.66 /100,000. There were 5 298 male cases (60.60%), and 3,444 female cases (39.40%). The incidence rate decreased from 2.73/100 000 in 2010 to 1.38/100 000 in 2020. The onset seasonality was strong in 2010, but there was no obvious seasonality in other years. A total of 5 891 cases (67.39%) were aged from 25 to 64 years. Farmers accounted for 59.79% of the cases. A total of 7 hepatitis A outbreaks were reported during 2010-2020, including 273 cases，accounting for 3.12% of the total cases．The incidence rates of hepatitis A in Hezhou (3.97/100 000), Wuzhou (2.98/100 000), Hechi (2.44/100 000), Guigang (2.00/100 000) and Beihai (1.79/100 000) were relatively higher than other places. Conclusion The number of reported hepatitis A cases in Guangxi has been declining year by year, and the prevention and control measures of hepatitis A vaccine prevention are effective. The surveillance of hepatitis A should be strengthened, and prevention and control strategies should be formulated for high-risk areas and key populations.

Objective:To observe the effect of electroacupuncture at Baihui (DU20) and Shenshu (BL23) acupoints on learning-memory ability and expression of the relative protein of P35/P25-cyclin-dependent kinase 5 (CDK5)-Tau phosphorylation signaling pathway in the prefrontal cortex (PFC) in rats with Alzheimer's disease (AD), so as to reveal its potential mechanisms in treating AD. Methods:Male adult Sprague-Dawley rats were randomly divided into normal control group, sham group, model group and treatment group with six rats in each group. The AD model was constructed by bilateral hippocampal injection of Aβ_25-35 in latter two groups. Equal amount of normal saline was injected into the sham group. The treatment group was acupunctured at Baihui and Shenshu once a day for ten days. All the rats were tested with Morris Water Maze. Immunohistochemistry staining and Western blotting were used to detect the related protein of P35/P25-CDK5-Tau protein phosphorylation in the PFC. Results:Compared with the normal control group and the sham group, the escape latency and escape length increased (P < 0.05) and the times crossing the platform reduced (P < 0.05) in the model group; compared with the model group, the escape latency and escape length reduced (P < 0.05), and the times crossing the platform increased (P < 0.05) in the treatment group. The optical density of P35/P25 and CDK5 were significantly higher in the model group than in the normal control group and the sham group (P < 0.01), and they were lower in the treatment group than in the model group (P < 0.001). The relative expression of P35/P25, CDK5, Tau[pS199] and Tau[pS202] were higher in the model group than in the normal control group and the sham group (P < 0.05), and the expression of the above proteins was lower in the treatment group than in the model group (P < 0.05). Conclusion:Electroacupuncture could improve the learning-memory and spatial exploration ability, which associate with inhabiting the P35/P25-CDK5-Tau protein phosphorylation signaling pathway in the PFC to delay the development of AD.

Catalpol is the main active ingredient of an extract from Radix rehmanniae, which in a previous study showed a protective effect against various types of tissue injury. However, a protective effect of catalpol on uterine inflammation has not been reported. In this study, to investigate the protective mechanism of catalpol on lipopolysaccharide (LPS)-induced bovine endometrial epithelial cells (bEECs) and mouse endometritis, in vitro and in vivo inflammation models were established. The Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling pathway and its downstream inflammatory factors were detected by enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), western blot (WB), and immunofluorescence techniques. The results from ELISA and qRT-PCR showed that catalpol dose-dependently reduced the expression of pro-inflammatory cytokines such as tumor necrosis factor α (TNF-α), interleukin (IL)-1β, and IL-6, and chemokines such as C-X-C motif chemokine ligand 8 (CXCL8) and CXCL5, both in bEECs and in uterine tissue. From the experimental results of WB, qRT-PCR, and immunofluorescence, the expression of TLR4 and the phosphorylation of NF-κB p65 were markedly inhibited by catalpol compared with the LPS group. The inflammatory damage to the mouse uterus caused by LPS was greatly reduced and was accompanied by a decline in myeloperoxidase (MPO) activity. The results of this study suggest that catalpol can exert an anti-inflammatory impact on LPS-induced bEECs and mouse endometritis by inhibiting inflammation and activation of the TLR4/NF-κB signaling pathway.
Animals ; Cattle ; Chemokines/genetics* ; Cytokines/genetics* ; Endometritis/drug therapy* ; Epithelial Cells/drug effects* ; Female ; Inflammation/prevention & control* ; Iridoid Glucosides/therapeutic use* ; Lipopolysaccharides/pharmacology* ; Mice ; NF-kappa B/physiology* ; Signal Transduction/drug effects* ; Toll-Like Receptor 4/physiology*

Chlortetracycline (CTC), one kind of common antibiotic for prevention and treatment of various diseases, also exhibits good performance in accelerating the growth of livestock. Macleaya cordata, a traditional Chinese medicine, is usually used as a natural additive in livestock because of its anti-microbial, anti-fungal, anti-inflammatory, and pesticidal activity. In this work, we studied whether M. cordata helps regulate the growth-promoting effect of CTC on broiler chickens. It is demonstrated that M. cordata improves the growth-promoting effect of CTC on growth performance indices of broiler chickens, such as survival rate, daily weight, and feed to weight rate. M. cordata also delays the maximum of CTC residues in plasma. It may depend on the higher values of operational taxonomic unit (OTU) and the indices of α diversity driven by simultaneous use of CTC and M. cordata.
Animals ; Anti-Bacterial Agents/pharmacology* ; Chickens/growth & development* ; Chlortetracycline/pharmacology* ; Drugs, Chinese Herbal/pharmacology* ; Duodenum/pathology* ; Female ; Gastrointestinal Microbiome ; Male ; Medicine, Chinese Traditional

This study aims to prepare lipid bilayer-coated calcium phosphate core-shell nanoparticles (LCAPNs), which can dissolve in an acidic environment to improve the tumor cell toxicity of antitumor drug. Paclitaxel (PTX) loaded lipid coated calcium phosphate nanoparticles (PTX-LCAPNs) were prepared by thin-film dispersion method. The morphology, particle size and in vitro release behavior were characterized. Meanwhile, the intracellular uptake, intracellular dissolution, cell toxicity of PTX-LCAPNs and intracellular accumulation of PTX were evaluated in human HCC cell line (Huh-7). The results suggested that the mean diameter of the spherical LCAPNs was 124.73±6.41 nm. The PTX-LCAPNs demonstrated little drug leakage in simulated normal physiological conditions, while a rapid release was observed in simulated intracellular condition in vitro. Moreover, the PTX-LCAPNs achieved 1.7 fold improvement in the intracellular PTX concentration leading to 5-fold reduction in half maximal inhibitory concentration (IC₅₀) values of PTX compared with calcium phosphate nanoparticles loaded with PTX (PTX-CAPNs), demonstrating a stronger cancer cell lethality.

This study aims to synthesize new phospholipids, 1,3-dipalmaminophospholipid(Pad-PC-Pad), and prepare shear-stress sensitive liposomes(SSSL). ¹H NMR and MS indicated that Pad-PC-Pad were fully synthesized successfully. SSSL were prepared by filming-rehydration method with Pad-PC-Pad, which loaded calcein with aggregation-caused quenching(ACQ)characteristics to evaluate shear-stress sensitivity of liposomes and release behavior of liposomes in vitro. The results showed that the particle size of liposomes was 106.91 ± 1.24 nm and liposomes had lenticular morphology under transmission electron microscope. The release of calcein was increased with ultrasonic power, which suggests that the liposomes is shear-stress sensitive. Moreover, the liposomes exhibited a releasing effect for obstructed region under high shear-stress in a model system. Therefore, we synthesized quick functional phospholipid Pad-PC-Pad and the liposomes made from Pad-PC-Pad was shear-stress sensitive, which may be used for treatment of thrombosis.

BACKGROUNDEverlasting cellular proliferation is the fundamental feature during gliomagenesis and Ki-67 is one of the classical proliferation markers in human glioblastoma multiforme (GBM). However, the driver genes or core pathways for cellular proliferation in GBM have not been elucidated systematically.

METHODSWe evaluated by immunohistochemistry the prognostic value of Ki-67 expression in the clinical outcome of 156 Chinese patients with GBM and a total of 64 GBM samples were selected for further Agilent genome-wide microarray analysis. On the basis of the microarray data from Tiantan (n = 64) and The Cancer Genome Atlas (TCGA) (n = 202) database, differentially expressed genes between the GBM subgroups with high or low level of Ki-67 expression were identified using Significance Analysis of Microarrays (SAM). Gene Ontology (GO) and KEGG Pathway analyses were then undertaken for the Ki-67 associated genes to identify the most significant biological processes and signaling pathways.

RESULTSWe confirmed that Ki-67 was an independent prognostic indicator in the largest Chinese patient cohort of 156 GBM samples via immunohistochemical staining. Survival analysis of Ki-67 over-expression revealed a highly significant association with a worse clinical outcome (P = 0.010 for progression-free survival; P = 0.007 for overall survival). Comparative and integrated analysis between Tiantan and TCGA database identified a 247-gene "proliferation signature" (205 up-regulated and 42 down-regulated genes) that distinguished Ki-67 expression phenotypes. GO and KEGG Pathway analyses further indicated that Ki-67 expression phenotype was associated with distinct changes in gene expression associated with the regulation of cellular growth and proliferation.

CONCLUSIONSProliferation marker Ki-67 is an independent prognostic indicator in Chinese GBM patients. And Ki-67 associated proliferation signature identified through genome-wide microarray analysis may provide potential targets for anti-proliferation therapy in GBM.

Cell Proliferation ; Computational Biology ; Gene Expression Profiling ; methods ; Glioblastoma ; genetics ; metabolism ; Humans ; Immunohistochemistry ; In Vitro Techniques ; Ki-67 Antigen ; genetics ; metabolism ; Oligonucleotide Array Sequence Analysis