Dual cross-linked COL1/HAp bionic gradient scaffolds containing human amniotic mesenchymal stem cells promote rotator cuff tendon-bone interface healing.

The tendon-bone interface heals through scar tissue, while the lack of a natural interface gradient structure and collagen fibre alignment leads to the occurrence of retearing. Therefore, the promotion of tendon healing has become the focus of regenerative medicine. The purpose of this study was to develop a gradient COL1/ hydroxyapatite (HAp) biomaterial loaded with human amniotic mesenchymal stem cells (hAMSCs). The performance of common cross-linking agents, Genipin, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS), and dual cross-linked materials were compared to select the best cross-linking mechanism to optimize the biological and mechanical properties of the scaffold. The optimal COL1/HAp-loaded with hAMSCs were implanted into the tendon-bone rotator cuff interfaces in rats and the effect on the tendon-bone healing was assessed by micro-CT, histological analysis, and biomechanical properties. The results showed that Genipin and EDC/NHS dual cross-linked COL1/HAp had good biological activity and mechanical properties and promoted the proliferation and differentiation of hAMSCs. Animal experiments showed that the group using a scaffold loaded with hAMSCs had excellent continuity and orientation of collagen fibers, increased fibrocartilage and bone formation, and significantly higher biomechanical functions than the control group at the interface at 12 weeks post operation. This study demonstrated that dual cross-linked gradient COL1/HAp-loaded hAMSCs could promote interface healing, thereby providing a feasible strategy for tendon-bone interface regeneration.

Development and Validation of a Predictive Model for Chronic Postsurgical Pain After Arthroscopic Rotator Cuff Repair: A Prospective Cohort Study.

Purpose: Chronic pain management continues to present a significant challenge following arthroscopic shoulder surgery. Our purpose was to detect chronic postsurgical pain (CPSP) in patients who had undergone arthroscopic rotator cuff repair (ARCR) and develop a nomogram capable of predicting the associated risk. Patients and Methods: We collected the demographic and clinical data of 240 patients undergoing ARCR in our hospital from January 2021 to May 2022. The pain level was monitored and evaluated three months after ARCR. LASSO regression was used to screen out pain-predicting factors, which were subsequently used to construct a nomogram. Internal validation was carried out using Bootstrap resampling. The data of 78 patients who underwent ARCR in our hospital from August 2022 to December 2022 were also collected for external verification of the nomogram. The predictive model was evaluated using the receiver operating characteristic curve (ROC), calibration curve, and decision curve analysis (DCA). Results: Age, duration of preoperative shoulder pain (DPSP), C-reactive protein (CRP), number of tear tendons, and American Shoulder and Elbow Surgical Score (ASES) were screened by LASSO regression as predictive factors for CPSP. These factors were then used to construct a chronic pain risk nomogram. The area under the curve (AUC) of the predictive and validation models were 0.756 (95% CI: 0.6386-0.8731) and 0.806 (95% CI: 0.6825-0.9291), respectively. Furthermore, the calibration curves and decision curve analysis (DCA) for both models indicated strong performance, affirming the reliability of this predictive model. Conclusion: The CPSP risk model that has been developed exhibits strong predictive capabilities and practical utility. It offers valuable support to clinical healthcare professionals in making informed treatment decisions, reducing the unnecessary use of analgesic drugs, and optimizing the allocation of medical resources.

Upconversion Properties and Temperature-Sensing Behaviors of Alkaline-Earth-Metal Scandate Nanocrystals Doped with Er3+/Yb3+ Ions in the Presence of Alkali Ions (Li+, Na+, and K+).

Temperature-sensing media based on the fluorescence intensity ratio (FIR) of upconversion materials that suffer from low sensitivity owing to the small energy gap still have a need for new compounds with strong upconversion luminescence (UCL). In this work, a series of MSc2O4:Er3+/Yb3+ (M = Mg, Ca, Sr, and Ba) nanocrystals were prepared by a hydrothermal method using NaOH alkaline solution. The structure, morphology, and UCL characteristics of materials were investigated, and the red UCL of the CaSc2O4:Er3+/Yb3+ sample was dramatically enhanced by a factor of ∼12, ∼23, and ∼2000 compared with SrSc2O4, MgSc2O4, and BaSc2O4 samples, respectively. By adjusting alkali ions (Li+, Na+, K+), the UCL intensities of CaSc2O4:Er3+/Yb3+ and SrSc2O4:Er3+/Yb3+ samples were further improved, especially in the presence of Li+ ions. Excellent temperature-sensing behaviors are realized for CaSc2O4:Er3+/Yb3+ and SrSc2O4:Er3+/Yb3+ samples in the presence of Li+ ions, in which the maximum absolute sensitivity SA values are about 0.0041 and 0.0036 K-1 at 600 K and the corresponding relative sensitivity SR values are expressed as 1197/T2 and 1129/T2 (the current optimal SR = 1289/T2), respectively. The intense UCL and excellent SA and SR values indicate that CaSc2O4:Er3+/Yb3+ and SrSc2O4:Er3+/Yb3+ materials are promising candidates for application in high-temperature sensors working under 980 nm excitation.

Silicon oxide-protected nickel nanoparticles as biomass-derived catalysts for urea electro-oxidation.

The urea electro-oxidation reaction (UOR) is explored as a new technique for energy conversion and the removal of urea via electrochemical means in wastewater. Nickel (Ni) nanoparticles grown on nanosheets were prepared by a facile hydrothermal reaction and a subsequent calcination process of silicon oxide/nitrogen-doped carbon (SiOx/NC) as the precursor, in which SiOx/NC with a natural three-dimensional (3D) interconnected structure was obtained from bamboo leaves. The nickel/silicon oxide/nitrogen-doped carbon (Ni/SiOx/NC, denoted as Y) obtained at 900 °C (Y3), exhibits the most optimal catalytic properties for the UOR with a low potential of 1.384 V vs. RHE at 10 mA cm-2. The protective role of SiOx was also explored via the partial etching of SiOx (Y3-NaOH), and the results show that the overpotential of the curve increased rapidly after long-term test. The findings indicate that full exploitation of the comprehensive advantages of biomass materials is beneficial for alleviating the problems encountered in the development of energy-related technologies.

Synthesis of Co0.5 Mn0.1 Ni0.4 C2 O4 ⋠n H2 O Micropolyhedrons: Multimetal Synergy for High-Performance Glucose Oxidation Catalysis.

Owing to the synergy between metals, trimetal oxalate micropolyhedrons have been synthesized by means of a room-temperature coprecipitation strategy. The effect of their nanoscale size on their electrochemical performance toward glucose oxidation was investigated. In particular, the Co0.5 Mn0.1 Ni0.4 C2 O4 ⋅n H2 O micropolyhedrons illustrated prominent electrocatalytic activity for the glucose oxidation reaction. Additionally, the Co0.5 Mn0.1 Ni0.4 C2 O4 ⋅n H2 O micropolyhedrons, when used as an electrode material, illustrated an excellent lower limit of detection (1.5 µm), a wide detection concentration range (0.5-5065.5 µm), and a high sensitivity (493.5 µA mm-1 cm-2 ). Further analysis indicated that the effectively improved conductivity may have been due to the small size of the materials, and it was easier to form a flat film when Nafion was coated onto the glassy carbon electrode.

Crystal structure of the condensation domain from lovastatin polyketide synthase.

The highly reducing iterative polyketide synthases responsible for lovastatin biosynthesis contains a section homologous to condensation (CON) domain observed in nonribosomal peptide synthetases (NRPSs). In the present study, we expressed the isolated lovastatin CON domain and solved the crystal structure to 1.79 Šresolution. The overall structure shows similarity to canonical condensation domains of NRPSs, containing the N-terminal and C-terminal subdomains that resemble enzymes of chloramphenicol acetyltransferase family, whereas distinct structural features are observed at the active site. The acceptor entry of the substrate channel is blocked by a flexible loop, thereby preventing the loading of substrate for a new round of chain elongation. The mutation of conserved catalytic motif located at the midpoint of substrate channel agrees with the incapability of CON to catalyzed amide-bond formation. The structure helps to understand the function of CON in lovastatin biosynthesis.

Substrate-bound structures of a ketoreductase from amphotericin modular polyketide synthase.

Ketoreductase (KR) domains of modular polyketide synthases (PKSs) control the stereochemistry of C2 methyl and C3 hydroxyl substituents of polyketide intermediates. To understand the molecular basis of stereocontrol exerted by KRs, the crystal structure of a KR from the second module of the amphotericin PKS (AmpKR2) complexed with NADP+ and 2-methyl-3-oxopentanoyl-pantetheine was solved. This first ternary structure provides direct evidence to the hypothesis that a substrate enters into the active site of an A-type KR from the side opposite the coenzyme to generate an L-hydroxyl substituent. A comparison with the ternary complex of a G355T/Q364H mutant sheds light on the structural basis for stereospecificity toward the substrate C2 methyl substituent. Functional assays suggest the pantetheine handle shows obvious influence on the catalytic efficiency and the stereochemical outcome. Together, these findings extend our current understanding of the stereochemical control of PKS KR domains.

Stereospecificity of Enoylreductase Domains from Modular Polyketide Synthases.

An enoylreductase (ER) domain of a polyketide synthase module recruiting a methylmalonate extender unit sets the C2 methyl branch to either the S or R configuration during processing of a polyketide intermediate carried by an acyl carrier protein (ACP) domain. In the present study, pantetheine- and ACP-bound trans-2-methylcrotonyl substrate surrogates were used to scrutinize the stereospecificity of the ER domains. The pantetheine-bound thioester was reduced to mixtures of both 2 R and 2 S products, whereas the expected 2 S epimer was almost exclusively generated when the cognate ACP-bound substrate surrogate was utilized. The analogous incubation of an ER with the substrate surrogate carried by a noncognate ACP significantly increased the generation of the unexpected 2 R epimer, highlighting the dependence of stereospecificity on proper protein-protein interactions between ER and ACP domains. The ER mutant assays revealed the involvement of the conserved tyrosine and lysine in stereocontrol. Taken together, these results expand the current understanding of the ER stereochemistry and help in the engineering of modular PKSs.

Applications of α-phosphonovinyl tosylates in the synthesis of α-arylethenylphosphonates via Suzuki-Miyaura cross-coupling reactions.

It has been demonstrated for the first time that α-phosphonovinyl tosylates could efficiently couple with a range of arylboronic acids to access α-arylethenylphosphonates. The unprecedented procedure exhibits excellent functional group tolerance, giving the terminal vinylphosphonates in good to excellent isolated yields (60-99%) under mild reaction conditions.

[Study on femoral 3D reconstruction and computer aid low-temperature deposition manufacturing].

Serious femoral damages are a common human bone disease. Rebuilding the femur and studying its mechanical properties are a continuous medical research topic, but traditional femoral prosthesis often cause some problems such as prosthesis loosening. In this work, we selected a healthy male, took his femur scanning by CT, and rebuilt high-precision femur prototypes by Mimics10.0 software, then chose the material having good biocompatibility and biodegradable, utilizing low-temperature deposition manufacturing (LDM) technology for the femoral manufacturing. This approach, fabricating the femur via LDM technology, laid a foundation for the later research on the femoral implantation in the human body.

[Design of a three-dimensionally controlled multi-cell-assembly system based on the control of a mixer nozzle].

Three-dimensionally controlled cell-assembly technique makes fabricating tissues and organs in vitro to be possible. However, for real tissues and organs with complex structure and various cells, fabricating tissues and organs in vitro need a technique that could assemble and locate multi cells and materials precisely in the space. Facing the needs of multi-cell assembly, we designed a mixer nozzle and the matching pulse switching circuit which based on the single-nozzle cell assembly system, and developed a multi-cell-assembly system. We also carried out some assembly experiments with this system using materials that were similar to the multi-component extracellular matrix materials. The results demonstrated that the system could assemble various cells and materials into three-dimensional inhomogeneous structures precisely.

[Study on computer-aided deposition manufacturing of vascular tissue engineering scaffolds at low temperature].

Since there is a clinical need for the tissue-engineered vascular graft (TEVG), fabricating the vascular scaffold individually appears to be necessary. In this work, we have developed the traditional tubular scaffold and branch vascular scaffold utilizing low-temperature deposition manufacturing (LDM) technology. Then different tubular scaffolds were fabricated by changing the processing parameters, and the morphological properties of the scaffolds were assessed. The scaffolds reproduced the structure of 3D vascular model accurately. Wall thickness of the scaffold increased with the increase of velocity ratio (V(L)/V(s)) and nozzle temperature, and both the micropore size and wall roughness were positively correlated with the nozzle temperature. However, the porosity was barely affected by the nozzle temperature. This approach, fabricating vascular scaffold with special structure and appearance features via LDM technology, is potential for the individual fabrication of vascular scaffold.

Protective effects of baicalin and octreotide on intestinal mucosa of rats with severe acute pancreatitis.

BACKGROUND/AIMS: To compare the protective effects of baicalin and octreotide on intestinal mucosa of rats with severe acute pancreatitis and to explore the application value of baicalin as a new drug. METHODS: Severe acute pancreatitis rats were randomly divided into a model control group, baicalin-treated group and octreotide-treated group. An equal number of normal rats were included in a sham-operated group. At 3, 6 and 12 hours (h) after operation, mortality rate, pathological changes in the intestinal mucosa of the terminal ileum, expression levels of nuclear factor (NF)-kappaB, Bax and Bcl-2 proteins, and apoptosis indices in the rats in each group were evaluated. Endotoxin and tumor necrosis factor (TNF)-alpha contents in blood were also determined. RESULTS: At 12h after operation, the survival rates in both the baicalin-treated group and octreotide-treated group were higher than in the model control group, and the difference was significant (p<0.05). At all time points after the operation, endotoxin and TNF-alpha values as well as the expression levels of NF-kappaB protein and pathological severity scores in the intestinal mucosa in the two treated groups were, to varying degrees, significantly lower than those in the model control group (p<0.05, p<0.01 and p<0.001, respectively). Moreover, the expression level of Bax protein at 3h postoperatively as well as the expression level of Bax protein and apoptosis indices at 6h postoperatively in the two treated groups were significantly higher than those in the model control group (p<0.01). CONCLUSIONS: Baicalin and octreotide exert significant protective effects on severe acute pancreatitis-induced intestinal mucosa injury via a mechanism that is associated with inhibiting inflammatory mediators and inducing apoptosis. In comparison with the pharmacological action of octreotide, we believe that baicalin, as a new drug, has similar protective effects on the intestinal mucosa of severe acute pancreatitis rats, and therefore deserves further study and development.