The repair of bone defects is heavily influenced by the dynamic osteogenic microenvironment. Static scaffolds constructed by traditional 3D printing technology cannot simulate the dynamic nature of the microenvironment during bone defect repair due to the fixed structure, uncontrollable release of active factors, and difficult regeneration of blood vessels, among other factors. Breaking through the limitations of these static scaffolds and realizing the intelligent and dynamic regulation of the osteogenic microenvironment is a key scientific issue in the field of bone tissue engineering. 4D printing technology combines the dynamic responsiveness of bone restoration materials with the concept of intelligent design to regulate the micro and macro structure of scaffolds. This technology provides a new method for bone tissue engineering by responding to endogenous and exogenous stimuli and creating a better osteogenic microenvironment through functionalized design, including drug delivery and antibacterial function. However, this technology currently suffers from challenges related to dynamic response material design, insufficient precision of printing technology, and mismatches between multi-stimulus response systems, metabolic rhythms of bone tissue, and functionalized composite scaffolds. Future research should focus on the development of smart response materials with excellent dynamic responses and bioactivity, the creation of new printing technologies, and the design of personalized and precise bone repair solutions. The aim of this paper is to review the current research status of 4D printing for bone tissue engineering in terms of material types, response mechanisms, and applications to provide a theoretical basis for the development and clinical application of functional bone repair materials in the future.

ObjectiveTo investigate the association of physical activity and balance ability with disability, and to further examine the mediating role of balance ability in the relationship between physical activity and disability. MethodsBased on data from 2021 to 2023 National Health and Nutrition Examination Survey (NHANES) cycle, a multivariable Logistic regression model was constructed to evaluate the independent association of physical activity and balance ability with disability, with covariates adjusted in four steps. An interaction model was further developed to assess the multiplicative interaction between physical activity and balance ability. Mediation analysis was performed using the Baron and Kenny three-step approach to examine the mediating role of balance ability, and the proportion of the mediation effect was calculated. The significance of the mediation effect was assessed using the Delta method, and robustness was verified through the Bootstrap method with a fixed random seed. Multiple sensitivity analyses were conducted to ensure the stability of the results. ResultsA total of 3 902 participants were included, with a prevalence of disability of 17.7%. Multivariable regression analysis showed that, after adjusting for all covariates, both light-intensity physical activity (LIPA) (OR = 0.489, 95%CI 0.380 to 0.629, P < 0.001) and high-intensity physical activity (HIPA) (OR = 0.493, 95%CI 0.371 to 0.656, P < 0.001) were significantly associated with a reduced risk of disability, whereas impaired balance ability was significantly associated with an increased risk (OR = 1.579, 95%CI 1.266 to 1.970, P < 0.001). The interaction effect analysis showed that the interaction between physical activity and balance ability were not significant (P > 0.05), however, the main effect of LIPA remained robust (β = -0.597, SE = 0.221, OR = 0.550, P = 0.007), while impaired balance ability was significantly associated with an increased risk of disability (β = 0.577, SE = 0.231, OR = 1.780, P = 0.012). The mediation analysis further indicated that balance ability played a robust mediating role in the association between LIPA and disability, with a mediation proportion of 21.1%. The indirect effect (a × b) was statistically significant (P < 0.001), and the 95% confidence intervals derived from the bootstrap method did not include zero. ConclusionPhysical activity and balance ability are significantly associated with disability, and balance ability may mediate the relationship between physical activity and disability, highlighting its potential value in disability risk assessment and intervention strategies.

Acute-on-chronic liver failure （ACLF） is a syndrome of multiple organ failure on the basis of underlying chronic liver disease and has an extremely high short-term mortality rate， while there is still a lack of unified diagnostic criteria around the world. Radiology plays an important role in the evaluation and prognostic prediction of ACLF， constituting a multi-dimensional assessment system covering morphology， function， and hemodynamics. Computed tomography can be used for the measurement of liver volume and the diagnosis of sarcopenia by providing key morphological and nutritional parameters. Magnetic resonance imaging （MRI）， especially gadobenate dimeglumine-enhanced MRI， enables quantitative assessment of liver function and has critical significance for predicting short-term survival rate. Ultrasonography and elastography techniques facilitate the early warning of ACLF onset and the dynamic monitoring of its progression through noninvasive measurement of liver stiffness and hemodynamic parameters. This article systematically reviews the pivotal role of these three imaging modalities in the diagnosis and monitoring of ACLF， and integrating the strengths of multiple imaging techniques with clinical indicators to construct diagnostic and prognostic models may become a key future direction for achieving early intervention and improving clinical outcomes in ACLF.

ObjectiveTo express and purify the endolysin PlyL from the Bacillus anthracis prophage LambdaBa02 in prokaryotic cells, and to explore its role in the detection of Bacillus anthracis, so as to provide a novel strategy for the specific and rapid detection of Bacillus anthracis.MethodsAccording to the sequence of Bacillus anthracis vaccine strain CVCC40205 registered in GenBank, the plyL gene was amplified by PCR with plyL gene-specific primers and inserted into the prokaryotic expression vector pET28a(+) to construct the recombinant expression plasmid pET28a(+)-His-plyL, which was then transformed into E.coli BL21(DE3) and induced by IPTG. The induced expression conditions were optimized to enhance soluble expression, and the recombinant PlyL protein was purified via nickel-affinity chromatography. The lytic activity of recombinant PlyL protein was assessed by measuring absorbance values, and an ELISA method was established to evaluate the sensitivity and specificity of Bacillus anthracis detection.ResultsThe recombinant expression plasmid pET28a(+)-His-plyL was confirmed to be correctly constructed by NdeⅠ and XhoⅠ double digestion and sequencing. The optimal induction conditions were 0. 5 mmol/L IPTG at 16 ℃ for 16 h. The relative molecular mass of the expressed recombinant PlyL protein was about 28 600. After purification and concentration, the final concentration of the protein was2. 55 mg/mL, and the purity reached 80. 6%. The purified recombinant PlyL protein could reduce the A_(600)value of Bacillus anthracis culture solution. The sensitivity of the preliminarily established ELISA method for detecting Bacillus anthracis was1 × 10~3 CFU/mL, and there was no cross-reactivity against closely related strains such as Bacillus cereus and Bacillus thuringiensis(P < 0. 000 1).ConclusionThe recombinant PlyL protein was successfully expressed and purified in prokaryotic cells, which exhibits both efficient lytic activity and species specificity, making it a promising novel tool for the rapid detection of Bacillus anthracis.

Meconium is changed from defoliated intestinal villi with apoptosis. A meconium corpuscle is a limited architecture in the meconium at the light microscopic level. In histological and immunohistochemical sections of the abdomen from 40 fetuses at 20–31 weeks of gestation, we found 12 fetuses with meconium and examined the architecture.A solid or loose meconium was seen depending on sites. The solid meconium in the colon and rectum contained numerous spherical or rugby ball-like corpuscles comprising of a core with tightly-packed atrophied cells and a laminar fibrous sheath.The solid meconium surrounded and incorporated villi that maintained the original architecture. The loose meconium was seen not only in the stomach and duodenum but also, depending on specimens, in the colon and rectum. It was composed of a large mucosal fold, a single small villus and/or fragmented epithelia. Notably, these mucosal tissues still contained chromogranin-positive gastrointestinal cells and cytokeratin-positive epithelia. A large ring-like meconium was composed of the entirely circular mucosa or epithelia that seemed to be detached along the muscularis mucosae or the basal lamina.A sheath-like fibrous structure in meconium seemed to originate from the lamina propria and basal lamina of villi. A defoliation of villi with apoptosis seemed difficult to explain a detachment of the entirely circular mucosa or epithelia in large fetuses examined. The latter event might require a specific mechanism such as an in utero intussusception in which a proximal side of the colon was invaginated into the distal lumen.

Macrophages are innate immune cells connected with the development of inflammation. Retinoic acid has previously been proved to have anti-inflammatory and anti-arthritic properties. However, the exact mechanism through which retinoic acid modulates arthritis remains unclear. This study aimed to investigate whether retinoic acid ameliorates rheumatoid arthritis by modulating macrophage polarization. This study used retinoic acid to treat mice with adjuvant arthritis and evaluated anti-inflammatory effects by arthritis score, thermal nociceptive sensitization test, histopathologic examination and immunofluorescence assays. In addition, its specific anti-arthritic mechanism was investigated by flow cytometry, cell transfection and inflammatory signaling pathway assays in RAW264.7 macrophages in vitro. Retinoic acid significantly relieved joint pain and attenuated inflammatory cell infiltration in mice. Furthermore, this treatment modulated peritoneal macrophage polarization, increased levels of arginase 1, as well as decreased inducible nitric oxide synthase expression. In vitro, we verified that retinoic acid promotes macrophage transition from the M1 to M2 type by upregulating mitogen-activated protein kinase (MAPK) phosphatase 1 (MKP-1) expression and inhibiting P38, JNK and ERK phosphorylation in lipopolysaccharide-stimulated RAW264.7 cells. Notably, the therapeutic effects of retinoic acid were inhibited by MKP-1 knockdown. Retinoic acid exerts a significant therapeutic effect on adjuvant arthritis in mice by regulating macrophage polarization through the MKP-1/MAPK pathway, and play an important role in the treatment of rheumatic diseases.

OBJECTIVE: To review clinical application and research progress of different types of intelligent responsive hydrogels in repairing articular cartilage injury. METHODS: The animal experiments and clinical studies of different types of intelligent responsive hydrogels for repairing articular cartilage injury were summarized by reviewing relevant literature at home and abroad. RESULTS: The intrinsic regenerative capacity of articular cartilage following injury is limited. Intelligent responsive hydrogels, including those that are temperature-sensitive, light-sensitive, enzyme-responsive, pH-sensitive, and other stimuli-responsive hydrogels, can undergo phase transitions in response to specific stimuli, thereby achieving optimal functionality. These hydrogels can fill the injured cartilage area, promote the proliferation and differentiation of chondrocytes, and expedite the repair of the damaged site. With advancements in cartilage tissue engineering materials research, intelligent responsive hydrogels offer a novel approach and promising potential for the treatment of cartilage injuries. CONCLUSION Intelligent responsive hydrogel is a kind of flexible, controllable, efficient, and stable polymer, which has similar structure and functional properties to articular cartilage, and has become one of the important biomaterials for cartilage repair. However, there is still a lack of unified treatment standards and simple and efficient preparation technology.
Hydrogels/therapeutic use* ; Cartilage, Articular/injuries* ; Tissue Engineering/methods* ; Humans ; Animals ; Chondrocytes/cytology* ; Biocompatible Materials/chemistry* ; Tissue Scaffolds/chemistry*

BACKGROUND: The mechanisms distinguishing metabolically healthy from unhealthy phenotypes within the same BMI categories remain unclear. This study aimed to investigate the associations between regional fat distribution and metabolically unhealthy phenotypes in Chinese adults across different BMI categories. METHODS: This cross-sectional study involving 11833 Chinese adults aged 20 years and older. Covariance analysis, adjusted for age, compared the percentage of regional fat (trunk, leg, or arm fat divided by whole-body fat) between metabolically healthy and unhealthy participants. Trends in regional fat percentage with the number of metabolic abnormalities were assessed by the Jonckheere-Terpstra test. Odds ratios (ORs) and their 95% confidence intervals (CIs) were estimated by logistic regression models. All analyses were performed separately by sex. RESULTS: In non-obese individuals, metabolically unhealthy participants exhibited higher percent trunk fat and lower percent leg fat compared to healthy participants. Additionally, percent trunk fat increased and percent leg fat decreased with the number of metabolic abnormalities. After adjustment for demographic and lifestyle factors, as well as BMI, higher percent trunk fat was associated with increased odds of being metabolically unhealthy [highest vs. lowest quartile: ORs (95%CI) of 1.64 (1.35, 2.00) for men and 2.00 (1.63, 2.46) for women]. Conversely, compared with the lowest quartile, the ORs (95%CI) of metabolically unhealthy phenotype in the highest quartile for percent arm and leg fat were 0.64 (0.53, 0.78) and 0.60 (0.49, 0.74) for men, and 0.72 (0.56, 0.93) and 0.46 (0.36, 0.59) for women, respectively. Significant interactions between BMI and percentage of trunk and leg fat were observed in both sexes, with stronger associations found in individuals with normal weight and overweight. CONCLUSIONS Trunk fat is associated with a higher risk of metabolically unhealthy phenotype, while leg and arm fat are protective factors. Regional fat distribution assessments are crucial for identifying metabolically unhealthy phenotypes, particularly in non-obese individuals.
Adult ; Aged ; Female ; Humans ; Male ; Middle Aged ; Young Adult ; Adipose Tissue ; Body Fat Distribution ; Body Mass Index ; China/epidemiology* ; Cross-Sectional Studies ; Health Surveys ; Phenotype