Immobilized enzyme-based enzyme electrode biosensors, characterized by high sensitivity and efficiency, strong specificity, and compact size, demonstrate broad application prospects in life science research, disease diagnosis and monitoring, etc. Immobilization of enzyme is a critical step in determining the performance (stability, sensitivity, and reproducibility) of the biosensors. Random immobilization (physical adsorption, covalent cross-linking, etc.) can easily bring about problems, such as decreased enzyme activity and relatively unstable immobilization. Whereas, directional immobilization utilizing amino acid residue mutation, affinity peptide fusion, or nucleotide-specific binding to restrict the orientation of the enzymes provides new possibilities to solve the problems caused by random immobilization. In this paper, the principles, advantages and disadvantages and the application progress of enzyme electrode biosensors of different directional immobilization strategies for enzyme molecular sensing elements by specific amino acids (lysine, histidine, cysteine, unnatural amino acid) with functional groups introduced based on site-specific mutation, affinity peptides (gold binding peptides, carbon binding peptides, carbohydrate binding domains) fused through genetic engineering, and specific binding between nucleotides and target enzymes (proteins) were reviewed, and the application fields, advantages and limitations of various immobilized enzyme interface characterization techniques were discussed, hoping to provide theoretical and technical guidance for the creation of high-performance enzyme sensing elements and the manufacture of enzyme electrode sensors.

OBJECTIVE To investigate the mechanism of catalpol affecting the differentiation of helper T cell 17 （Th17） by interfering the expressions of pyruvate kinase M2 （PKM2） and lactate dehydrogenase A （LDHA）. METHODS The naive CD4+ T cells were selected from the spleen of C57BL/6 mice， and were differentiated into Th17 cells by adding directional differentiation stimulants for 72 hours. At the same time， the cells were treated with 0 （directed control）， 20， 40 and 80 μg/mL catalpol. The flow cytometry was used to detect the proportion of Th17 cell differentiation in cells； the colorimetric method was adopted to detect the levels of pyruvate and lactate in cell culture supernatant； mRNA expressions of retinoid-related orphan nuclear receptor gamma t （RORγt）， PKM2 and LDHA were detected by qRT-PCR method； Western blot was used to detect the expression levels of PKM2， LDHA， signal transducer and activator of transcription 3 （STAT3）， and phosphorylated STAT3 （p-STAT3） proteins in cells. RESULTS Compared with the directed control group， after 72 hours of treatment with 20， 40， 80 μg/mL catalpol， the differentiation ratio of Th17 cells were decreased by 6.74%， 8.41%， 9.24%， and the levels of pyruvate and lactate in the cell culture supernatant， the mRNA expressions of PKM2， LDHA and RORγt as well as the protein expressions of PKM2 and LDHA and the phosphorylation of STAT3 were significantly reduced （P＜0.05）. CONCLUSIONS Catalpol can reduce the glycolysis level by down-regulating the expressions of PKM2 and LDHA， thereby inhibiting the differentiation of Th17 cells.

Objective To explore the effect of barretinib on mice with acute lung injury(ALI)by regulating the Janus kinase 2(JAK2)/signal transducer and activator of transcription 3(STAT3)pathway.Methods The male C57BL/6 mice were randomly divided into control group,model group and experimental-L,-M-H groups.Except for the control group,the other four groups were constructed ALI models by intraperitoneal injection of lipopolysaccharide.The control and model groups were given equal volume 0.9％NaCl by gavage.The experimental-H,-M,-L groups were administered with 1.00,0.50 and 0.25 mg·mL-1 barretinib solution 200 μL by gavage.Five groups were treated for 48 hours with once every 12 hours.The levels of inflammatory cytokine in bronchoalveolar lavage fluid were measured by enzyme linked immunosorbent assay.The expression levels of Occludin,JAK2 and STAT3 in mouse lung tissue were detected by Western blot.Results The levels of tumor necrosis factor-α in bronchoalveolar lavage fluid for experimental-M,-H groups,model group and control group were(228.48±25.41),(198.53±23.11),(317.32±32.85)and(48.93±2.59)ng·L-1;the levels of interleukin-6 were(118.81±14.85),(98.58±13.82),(172.23±25.94)and(49.47±3.06)ng·L-1;the relative expression levels of Occludin were 0.48±0.13,0.49±0.11,0.28±0.09 and 0.69±0.21;the phospho-JAK2/JAK2 ratios were 0.51±0.13,0.32±0.09,0.75±0.21 and 0.16±0.05;the phospho-STAT3/STAT3 ratios were 0.43±0.11,0.27±0.08,0.78±0.21 and 0.17±0.05,respectively.The differences of above indicators were statistically significant between the experimental-M,-H groups,control group and model group(all P＜0.05).Conclusion Barretinib can reduce the lung inflammatory response and improves the level of tight junction protein in lung tissue to protect ALI mice by inhibiting the JAK2/STAT3 signaling pathway.

Objective This study investigated the impact of occupational mercury(Hg)exposure on human gene transcription and expression,and its potential biological mechanisms. Methods Differentially expressed genes related to Hg exposure were identified and validated using gene expression microarray analysis and extended validation.Hg-exposed cell models and PTEN low-expression models were established in vitro using 293T cells.PTEN gene expression was assessed using qRT-PCR,and Western blotting was used to measure PTEN,AKT,and PI3K protein levels.IL-6 expression was determined by ELISA. Results Combined findings from gene expression microarray analysis,bioinformatics,and population expansion validation indicated significant downregulation of the PTEN gene in the high-concentration Hg exposure group.In the Hg-exposed cell model(25 and 10 μmol/L),a significant decrease in PTEN expression was observed,accompanied by a significant increase in PI3K,AKT,and IL-6 expression.Similarly,a low-expression cell model demonstrated that PTEN gene knockdown led to a significant decrease in PTEN protein expression and a substantial increase in PI3K,AKT,and IL-6 levels. Conclusion This is the first study to report that Hg exposure downregulates the PTEN gene,activates the PI3K/AKT regulatory pathway,and increases the expression of inflammatory factors,ultimately resulting in kidney inflammation.

Objective This study explored the potentially modifiable factors for depression and major depressive disorder (MDD) from the MR-Base database and further evaluated the associations between drug targets with MDD.Methods We analyzed two-sample of Mendelian randomization (2SMR) using genetic variant depression (n = 113,154) and MDD (n = 208,811) from Genome-Wide Association Studies (GWAS). Separate calculations were performed with modifiable risk factors from MR-Base for 1,001 genomes. The MR analysis was performed by screening drug targets with MDD in the DrugBank database to explore the therapeutic targets for MDD. Inverse variance weighted (IVW), fixed-effect inverse variance weighted (FE-IVW), MR-Egger, weighted median, and weighted mode were used for complementary calculation.Results The potential causal relationship between modifiable risk factors and depression contained 459 results for depression and 424 for MDD. Also, the associations between drug targets and MDD showed that SLC6A4, GRIN2A, GRIN2C, SCN10A, and IL1B expression are associated with an increased risk of depression. In contrast, ADRB1, CHRNA3, HTR3A, GSTP1, and GABRG2 genes are candidate protective factors against depression.Conclusion This study identified the risk factors causally associated with depression and MDD, and estimated 10 drug targets with significant impact on MDD, providing essential information for formulating strategies to prevent and treat depression.

Currently,human health due to corona virus disease 2019(COVID-19)pandemic has been seriously threatened.The coronavirus severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)spike(S)protein plays a crucial role in virus transmission and several S-based therapeutic approaches have been approved for the treatment of COVID-19.However,the efficacy is compromised by the SARS-CoV-2 evolvement and mutation.Here we report the SARS-CoV-2 S protein receptor-binding domain(RBD)inhibitor licorice-saponin A3(A3)could widely inhibit RBD of SARS-CoV-2 variants,including Beta,Delta,and Omicron BA.1,XBB and BQ1.1.Furthermore,A3 could potently inhibit SARS-CoV-2 Omicron virus in Vero E6 cells,with EC50 of 1.016 pM.The mechanism was related to binding with Y453 of RBD deter-mined by hydrogen-deuterium exchange mass spectrometry(HDX-MS)analysis combined with quan-tum mechanics/molecular mechanics(QM/MM)simulations.Interestingly,phosphoproteomics analysis and multi fluorescent immunohistochemistry(mIHC)respectively indicated that A3 also inhibits host inflammation by directly modulating the JNK and p38 mitogen-activated protein kinase(MAPK)path-ways and rebalancing the corresponding immune dysregulation.This work supports A3 as a promising broad-spectrum small molecule drug candidate for COVID-19.

The 2-(2-phenylethyl)chromones were separated from agarwood of Aquilaria agallocha Roxb. and their anti-KRAS mutant non-small cell lung cancer (NSCLC) activities were evaluated. 2-(2-Phenyethyl)chromones in agarwood were separated and purified by silica gel, RP-18 reverse phase silica gel, MCI gel CH20P, Diol, and semi preparative HPLC chromatography techniques, while the structures of the compounds were identified by extensive spectroscopic analysis, such as 1D and 2D NMR and ESI-MS. The cell counting kit 8 (CCK-8) assay was used to screen the anti-tumor activity of the isolated monomeric compounds on three KRAS-mutant NSCLC cells. The cell proliferation, cloning formation, adhesion ability, and cell cycle arrest activity of compound 8 were analyzed. Molecular docking and Western blot experiments were used to study the mechanism of compound 8. The in vivo anti-tumor activity of the compound 8 was evaluated by zebrafish cell derived xenograft (CDX) model. Nineteen known 2-(2-phenylethyl)chromones were isolated from the ethyl acetate extract of agarwood. On A549 (KRAS G12S) cells, compounds 8, 10, and 19 showed good inhibitory activity, on H23 (KRAS G12C) cells, compounds 7, 8, and 19 showed good inhibitory activity, and on H358 (KRAS G12C) cells, compounds 8, 10, and 16 showed good inhibitory activity. Compound 8 had the best inhibitory activity in all three cell lines. It effectively inhibited cell proliferation, clone formation, adhesion ability, and arrested the H23 cell cycle at G2/M phase. Compound 8 could also inhibit the expression of c-Met and its downstream signaling pathways, effectively inhibiting tumor growth in zebrafish CDX model. In conclusion, among the nineteen known 2-(2-phenylethyl)chromones, compound 8 had the best activity and significantly inhibited the proliferation of KRAS-mutant NSCLC cells by arresting the cells in the G2/M phase.

Objective To explore the modal testing method for the three-axis manned centrifuge under elastic boundary conditions with considerations on its complicated structure and high rotational inertia.Methods Modal testing was carried out with a three-axis manned centrifuge under elastic boundary conditions as the subject and a force hammer as the excitation source according to GJB 2706A-2008 Modal tests method for spacecraft and GB/T 11349.3-1992 Experimental determination of mechnical mobility measurements using impact excitation.Four times of hammering were carried out at each excitation position,and the data of the four times of hammering underwent linear average computation.Data acquisition was implemented with a three-axis accelerometer and a 64-channel data collector,and the modal data were analyzed using a frequency response function based on the Test.Lab modal test and analysis software.Results The coherence coefficient of the excitation signal was not lower than 0.8 in the 30 Hz band;the first three orders of the system's intrinsic vibrations were all torsional vibrations,with the frequencies of 9.15,15.66 and 19.22 Hz,respectively;the first order frequency of the system was about 9.15 Hz for both Z18 and Z21 excitation positions,and each of the second and third order frequencies similar situations were observed for also had a roughly equal value for the two excitation positions.Conclusion The force hammer testing method is applicable for the modal testing of the three-axis manned centrifuge,ensuring equipment safety and subject comfort.Referen-ces are provided for the following structural optimization design.[Chinese Medical Equipment Journal,2024,45(8):38-43]

Objective To design and implement a high-precision ear pulse wave physiological signal detection device for human centrifuge training to solve the problems in measurement and calibration of pilot ear pulse wave signal during human centrifuge training.Methods The high-precision ear pulse wave physiological signal detection device was composed of an ear pulse wave acquisition sensor,a signal acquisition and control unit and a host signal processing module.The ear pulse wave acquisition sensor had an ear-clip-like shape and consisted of an outer shell,an inner shell and an elastic steel plate;the signal acquisition and control unit was made up of an power supply module,a constant voltage module for the light source,a signal acquisition module,a master control module and a data transmission module,which had its software developed with an embedded system;the host signal processing module divided the signal processing into 2 phases of signal pre-processing and pulse wave signal monitoring and display.The detection performance of the device was verified by using a physiological electrical signal calibrator to test the ear pulse wave signals detected with the device;the effectiveness and stability of the device were validated by implementing human centrifuge training experiments with different loads.Results The voltage measurement error,amplitude-frequency characteristics and common mode rejection ratio detected by this device were all within the permitted ranges of JJG 760-2003 Verification Regulation for Electro Cardiac Monitor and JJG 954-2019 Verification Regulation of Digital Electroencephalographs;the device was capable of detecting the ear pulse wave signals of pilot during human centrifuge training in real time with little interference from motion and stable signal quality.Conclusion The device can accurately clarify the changes in the amplitude of the pilot's ear pulse wave during human centrifuge training and effectively reflect the changes in the pilot's cerebral blood flow under positive acceleration.[Chinese Medical Equipment Journal,2024,45(9):35-40]

Aim To explore whether platelet-derived growth factor C(PDGFC)derived from cancer-associat-ed fibroblasts(CAFs)can promote resistance of breast cancer cells to doxorubicin(DOX)and the underlying mechanisms.Methods CAFs and normal fibroblasts(NFs)were extracted from freshly resected breast cancer tissue and adjacent normal breast tissue respec-tively.Conditioned medium(CM)from CAFs and NFs was collected and co-cultured with breast cancer cells.Cell proliferation and toxicity were assessed using a Cell Counting Kit-8(CCK-8).The expression of PDG-FC in CAFs,NFs and corresponding CM was detected by Western blot and ELISA respectively.The influence of CAFs-CM on intracellular doxorubicin content in breast cancer cells was observed by fluorescence mi-croscopy.The impact of CAFs-CM on apoptosis-related proteins BAX and BCL2 was predicted and valifated u-sing the Starbase database and Western blot.The changes in ROS levels,mitochondrial membrane po-tential,and mitochondrial membrane proteins TOM20 and COX Ⅳ in breast cancer cells were measured using DCFH-DA fluorescence staining,JC-1 assay,and Western blot.Results CAFs-CM decreased the intra-cellular doxorubicin content and inhibited the sensitivi-ty of breast cancer cells to doxorubicin.Additionally,the expression of apoptosis protein BAX decreased while the anti-apoptotic protein BCL2 increased in breast cancer cells cultured with CAFs-CM.Further-more,CAFs-CM led to decreased ROS levels and in-creased mitochondrial membrane potential in breast cancer cells accompanied with elevated expression of mitochondrial membrane proteins TOM20 and COX Ⅳ.Further study found that PDGEF was highly expressed in CAFs and CAFs-CM,recombinant human PDGFC produced resistance of breast cancer cells to DOX simi-lar to CAFs-CM,and the specific inhibitors of PDGFRα significantly inhibited CAFs-CM.Further mechanistic studies revealed that PDGFC in CAFs-CM induced chemoresistance by activating PI3K-mTOR signaling pathway.Conclusion PDGFC secreted by CAFs promotes doxorubicin resistance in breast cancer cells through PI3K-mTOR signaling pathway,which provides a new perspective for the development of anti-cancer drugs targeting CAFs.