Publications by authors named "Bin Gong"

98 Publications

Exposure to binge ethanol and fatty acid ethyl esters exacerbates chronic ethanol-induced pancreatic injury in hepatic alcohol dehydrogenase deficient deer mice.

Am J Physiol Gastrointest Liver Physiol 2022 Jan 5. Epub 2022 Jan 5.

Department of Pathology, The University of Texas Medical Branch at Galveston, Galveston, TX, United States.

Alcoholic chronic pancreatitis (ACP) is a fibroinflammatory disease of the pancreas. However, metabolic basis of ACP is not clearly understood. In this study, we evaluated differential pancreatic injury in hepatic alcohol dehydrogenase deficient (ADH) deer mice fed chronic ethanol (EtOH), chronic plus binge EtOH, and chronic plus binge EtOH and fatty acid ethyl esters (FAEEs, nonoxidative metabolites of EtOH) to understand the metabolic basis of ACP. Hepatic ADH and ADH normal (ADH) deer mice were fed Lieber-DeCarli liquid diet containing 3% (w/v) EtOH for three months. One week before the euthanization, chronic EtOH fed mice were further administered with an oral gavage of binge EtOH with/without FAEEs. Blood alcohol concentration (BAC), pancreatic injury and inflammatory markers were measured. Pancreatic morphology, ultrastructural changes, endoplasmic reticulum (ER)/oxidative stress were examined using H & E staining, electron microscopy, immunostaining, and/or Western blot, respectively. Overall, BAC was substantially increased in chronic EtOH fed groups of ADH vs. ADH deer mice. A significant change in pancreatic acinar cell morphology, with mild to moderate fibrosis and ultrastructural changes evident by dilatations and disruption of ER cisternae, ER/oxidative stress along with increased levels of inflammatory markers were observed in the pancreas of chronic EtOH fed groups of ADH vs. ADH deer mice. Furthermore, chronic plus binge EtOH and FAEEs exposure elevated BAC, enhanced ER/oxidative stress and exacerbated chronic EtOH-induced pancreatic injury in ADH deer mice suggesting a role of increased body burden of EtOH and its metabolism under reduced hepatic ADH in initiation and progression of ACP.
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http://dx.doi.org/10.1152/ajpgi.00263.2021DOI Listing
January 2022

Study on fracture behavior of molars based on three-dimensional high-precision computerized tomography scanning and numerical simulation.

Int J Numer Method Biomed Eng 2021 Dec 4:e3561. Epub 2021 Dec 4.

Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian, China.

A series of three-dimensional (3D) numerical simulations are conducted to investigate the gradual failure process of molars in this study. The real morphology and internal mesoscopic structure of a whole tooth are implemented into the numerical simulations through computerized tomography scanning, digital image processing, and 3D matrix mapping. The failure process of the whole tooth subject to compressions including crack initiation, crack propagation, and final failure pattern is reproduced using 3D realistic failure process analysis (RFPA3D) method. It is concluded that a series of microcracks are gradually initiated, nucleated, and subsequently interconnect to form macroscopic cracks when the teeth are under over-compressions. The propagation of the macroscopic cracks results in the formation of fracture surfaces and penetrating cracks, which are essential signs and manifestations of the tooth failure. Moreover, the simulations reveal that, the material heterogeneity is a critical factor that affects the mechanical properties and fracture modes of the teeth, which vary from crown fractures to crown-root fractures and root fractures depending on different homogeneity indices.
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http://dx.doi.org/10.1002/cnm.3561DOI Listing
December 2021

NAP1L1 interacts with hepatoma-derived growth factor to recruit c-Jun inducing breast cancer growth.

Cancer Cell Int 2021 Nov 13;21(1):605. Epub 2021 Nov 13.

Cancer Center, Integrated Hospital of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China.

Background: Breast cancer is a common cancer among women in the world. However, its pathogenesis is still to be determined. The role and molecular mechanism of Nucleosome Assembly Protein 1 Like 1 (NAP1L1) in breast cancer have not been reported. Elucidation of molecular mechanism might provide a novel therapeutic target for breast cancer treatment.

Methods: A bioinformatics analysis was conducted to determine the differential expression of NAP1L1 in breast cancer and find the potential biomarker that interacts with NAP1L1 and hepatoma-derived growth factor (HDGF). The expression of NAP1L1 in tissues was detected by using immunohistochemistry. Breast cancer cells were transfected with the corresponding lentiviral particles and siRNA. The efficiency of transfection was measured by RT-qPCR and western blotting. Then, MTT, Edu, plate clone formation, and subcutaneous tumorigenesis in nude mice were used to detect the cell proliferation in breast cancer. Furthermore, coimmunoprecipitation (Co-IP) assay and confocal microscopy were performed to explore the detailed molecular mechanism of NAP1L1 in breast cancer.

Results: In this study, NAP1L1 protein was upregulated based on the Clinical Proteomic Tumor Analysis Consortium (CPTAC) database. Consistent with the prediction, immunohistochemistry staining showed that NAP1L1 protein expression was significantly increased in breast cancer tissues. Its elevated expression was an unfavorable factor for breast cancer clinical progression and poor prognosis. Stably or transiently knocking down NAP1L1 reduced the cell growth in vivo and in vitro via repressing the cell cycle signal in breast cancer. Furthermore, the molecular basis of NAP1L1-induced cell cycle signal was further studied. NAP1L1 interacted with the HDGF, an oncogenic factor for tumors, and the latter subsequently recruited the key oncogenic transcription factor c-Jun, which finally induced the expression of cell cycle promoter Cyclin D1(CCND1) and thus the cell growth of breast cancer.

Conclusions: Our data demonstrated that NAP1L1 functions as a potential oncogene via interacting with HDGF to recruit c-Jun in breast cancer.
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http://dx.doi.org/10.1186/s12935-021-02301-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8590370PMC
November 2021

Host EPAC1 Modulates Rickettsial Adhesion to Vascular Endothelial Cells via Regulation of ANXA2 Y23 Phosphorylation.

Pathogens 2021 Oct 12;10(10). Epub 2021 Oct 12.

Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA.

Introduction: Intracellular cAMP receptor exchange proteins directly activated by cAMP 1 () regulate obligate intracellular parasitic bacterium rickettsial adherence to and invasion into vascular endothelial cells (ECs). However, underlying precise mechanism(s) remain unclear. The aim of the study is to dissect the functional role of the signaling pathway during initial adhesion of rickettsiae to EC surfaces.

Methods: In the present study, an established system that is anatomically based and quantifies bacterial adhesion to ECs in vivo was combined with novel fluidic force microscopy (FluidFM) to dissect the functional role of the signaling pathway in rickettsiae-EC adhesion.

Results: The deletion of the gene impedes rickettsial binding to endothelium in vivo. Rickettsial OmpB shows a host -dependent binding strength on the surface of a living brain microvascular EC (BMEC). Furthermore, ectopic expression of phosphodefective and phosphomimic mutants replacing tyrosine (Y) 23 of in -knock out BMECs results in different binding force to reOmpB in response to the activation of .

Conclusions: modulates rickettsial adhesion, in association with Y23 phosphorylation of the binding receptor . Underlying mechanism(s) should be further explored to delineate the accurate role of cAMP- system during rickettsial infection.
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http://dx.doi.org/10.3390/pathogens10101307DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8537355PMC
October 2021

Intracellular receptor EPAC regulates von Willebrand factor secretion from endothelial cells in a PI3K-/eNOS-dependent manner during inflammation.

J Biol Chem 2021 11 20;297(5):101315. Epub 2021 Oct 20.

Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA. Electronic address:

Coagulopathy is associated with both inflammation and infection, including infections with novel severe acute respiratory syndrome coronavirus-2, the causative agent Coagulopathy is associated with both inflammation and infection, including infection with novel severe acute respiratory syndrome coronavirus-2, the causative agent of COVID-19. Clot formation is promoted via cAMP-mediated secretion of von Willebrand factor (vWF), which fine-tunes the process of hemostasis. The exchange protein directly activated by cAMP (EPAC) is a ubiquitously expressed intracellular cAMP receptor that plays a regulatory role in suppressing inflammation. To assess whether EPAC could regulate vWF release during inflammation, we utilized our EPAC1-null mouse model and revealed increased secretion of vWF in endotoxemic mice in the absence of the EPAC1 gene. Pharmacological inhibition of EPAC1 in vitro mimicked the EPAC1-/- phenotype. In addition, EPAC1 regulated tumor necrosis factor-α-triggered vWF secretion from human umbilical vein endothelial cells in a manner dependent upon inflammatory effector molecules PI3K and endothelial nitric oxide synthase. Furthermore, EPAC1 activation reduced inflammation-triggered vWF release, both in vivo and in vitro. Our data delineate a novel regulatory role for EPAC1 in vWF secretion and shed light on the potential development of new strategies to control thrombosis during inflammation.
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http://dx.doi.org/10.1016/j.jbc.2021.101315DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8526113PMC
November 2021

A novel chemical biology and computational approach to expedite the discovery of new-generation polymyxins against life-threatening .

Chem Sci 2021 Sep 19;12(36):12211-12220. Epub 2021 Aug 19.

Biomedicine Discovery Institute, Infection & Immunity Program, Monash University Melbourne Australia +61 3 9905 6450 +61 3 9903 9702.

Multidrug-resistant Gram-negative bacteria represent a major medical challenge worldwide. New antibiotics are desperately required with 'old' polymyxins often being the only available therapeutic option. Here, we systematically investigated the structure-activity relationship (SAR) of polymyxins using a quantitative lipidomics-informed outer membrane (OM) model of and a series of chemically synthesized polymyxin analogs. By integrating chemical biology and all-atom molecular dynamics simulations, we deciphered how each residue of the polymyxin molecule modulated its conformational folding and specific interactions with the bacterial OM. Importantly, a novel designed polymyxin analog FADDI-287 with predicted stronger OM penetration showed improved antibacterial activity. Collectively, our study provides a novel chemical biology and computational strategy to expedite the discovery of new-generation polymyxins against life-threatening Gram-negative 'superbugs'.
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http://dx.doi.org/10.1039/d1sc03460jDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8457388PMC
September 2021

Spin-Seebeck effect and thermoelectric properties of one-dimensional graphene-like nanoribbons periodically embedded with four- and eight-membered rings.

Phys Chem Chem Phys 2021 Oct 27;23(41):23667-23672. Epub 2021 Oct 27.

Hubei Key Laboratory of Optical Information and Pattern Recognition, Wuhan Institute of Technology, Wuhan, 430073, China.

The spin-Seebeck effect together with a high spin thermoelectric conversion efficiency has been regarded as one of the core topics in spin caloritronics. In this work, we propose a spin caloritronic device constructed on hydrogen-terminated sawtooth graphene-like nanoribbons periodically embedded with four- and eight-membered rings to investigate the thermal spin currents and thermoelectric properties by using density functional theory combined with the non-equilibrium Green's function method. Our theoretical results show that spin-Seebeck currents are induced by the temperature gradient between two leads due to two isolated spin-up and spin-down transport channels above or below the Fermi level. Besides, the embedded four- and eight-membered rings break the mirror symmetry of graphene-like nanoribbons and increase the phonon scattering to lower the lattice conductivity, contributing to the enhancement of the spin figure of merit. Moreover, the increasing width of the nanoribbons can effectively enhance the spin-Seebeck currents and reduce their threshold temperatures to improve the device performances. These systematic investigations not only give us an in-depth understanding into the realistic spin caloritronic device applications of graphene-like nanoribbons, but also help us to choose feasible routes to improve the spin-Seebeck effect with a high spin figure of merit in nanostructures.
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http://dx.doi.org/10.1039/d1cp03652aDOI Listing
October 2021

Study of PLSR-BP model for stability assessment of loess slope based on particle swarm optimization.

Authors:
Bin Gong

Sci Rep 2021 09 9;11(1):17888. Epub 2021 Sep 9.

State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian, 116024, China.

The assessment of loess slope stability is a highly complex nonlinear problem. There are many factors that influence the stability of loess slopes. Some of them have the characteristic of uncertainty. Meanwhile, the relationship between different factors may be complicated. The existence of multiple correlation will affect the objectivity of stability analysis and prevent the model from making correct judgments. In this paper, the main factors affecting the stability of loess slopes are analyzed by means of the partial least-squares regression (PLSR). After that, two new synthesis variables with better interpretation to the dependent variables are extracted. By this way, the multicollinearity among variables is overcome preferably. Moreover, the BP neural network is further used to determine the nonlinear relationship between the new components and the slope safety factor. Then, a new improved BP model based on the partial least-squares regression, which is initialized by the particle swarm optimization (PSO) algorithm, is developed, i.e., the PLSR-BP model. The network with global convergence capability is simplified and more efficient. The test results of the model show satisfactory precision, which indicates that the model is feasible and effective for stability evaluation of loess slopes.
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http://dx.doi.org/10.1038/s41598-021-97484-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8429688PMC
September 2021

Electrochemical biosensor for cytokinins based on the CHASE domain of Arabidopsis histidine kinases 4.

Bioelectrochemistry 2021 Oct 8;141:107872. Epub 2021 Jun 8.

College of Life Science, South-central University for Nationalities, Wuhan 430074, PR China. Electronic address:

In this study, An AHK4 CHASE domain was used to construct an electrochemical cytokinin biosensor using ferrocene as the electrochemical mediator. Upon addition of cytokinin, the binding of cytokinin and AHK4 led to dimerization, which blocked electron transfer between ferrocene and the electrode, and the redox peak current of ferrocene was gradually reduced. Cytokinin was detected by recording the change of the ferrocene redox peak current. The biosensor shows a linear range of 50-400 nM with a linear regression equation of i = 0.0086c + 0.732 (R = 0.993) with i in μA and c in nM and a detection limit (LOD) of 1.5 nM (S/N = 3). The biosensor exhibits excellent performance that avoids interference of other types of plant hormones and was successfully applied to the detection of cytokinins in bean sprouts.
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http://dx.doi.org/10.1016/j.bioelechem.2021.107872DOI Listing
October 2021

Highly efficient nano-Fe/Cu bimetal-loaded mesoporous silica Fe/Cu-MCM-41 for the removal of Cr(VI): Kinetics, mechanism and performance.

J Hazard Mater 2021 Sep 8;418:126344. Epub 2021 Jun 8.

Shaanxi provincial Center for Disease Control and Prevention, Xian 710054, China. Electronic address:

Zero valent iron (Fe) can reduce Cr(VI) in water, where Fe and Fe(Ⅱ) are possible electron donors, but passivation and aggregation easily occur to Fe. To improve the performance of Fe, a new hybridization strategy of Fe/Cu bimetal and silica-based mesoporous molecular sieve MCM-41 for the removal of Cr(VI) from water has been proposed. The results show that the two-dimensional mesoporous structure of MCM-41 can provide skeleton support for Fe, improve the mass transfer rate, and overcome the aggregation bottleneck of Fe. The Cr(VI) removal rate reached 98.98% (pH = 2) after 40 min. The analytical results revealed Cr(VI) removal process: Cr(VI) adsorbed onto Fe/Cu-MCM-41 by electrostatic attraction and other molecular inter-atomic forces. The second metal, Cu, can inhibit the passivation of Fe and promote Fe(Ⅱ)through the formation of Fe/Cu battery, thereby promoting the electron transfer. The resulting Cr(Ⅲ) is precipitated as FeCrO and CrFe(OH).
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http://dx.doi.org/10.1016/j.jhazmat.2021.126344DOI Listing
September 2021

Scalable synthesis of monodisperse and recyclable sulphonated polystyrene microspheres for sustainable elimination of heavy metals in wastewater.

Environ Technol 2021 Jun 20:1-13. Epub 2021 Jun 20.

School of Food Science and Engineering, South China University of Technology, Guangzhou, People's Republic of China.

Herein, we demonstrate a scalable method for fabricating monodisperse sulphonated polystyrene (SPS) microspheres with abundant sulphonic acid groups and excellent heavy metal removal ability. A comprehensive characterization through SEM, EDS, FT-IR, TG, XRD and XPS confirmed the formation of the SPS microspheres. Take advantage of the abundant sulphonic acid groups on the surface of microspheres, as well as the superior monodisperse properties, adsorption ability of SPS microspheres both in quantity and speed have been enhanced. The adsorption equilibrium obeyed the Langmuir isotherm model with the theoretical maximum capacities of 49.16, 15.38 and 13.89 mg·g for Pb, Zn and Cu, respectively (30°C, pH = 3.5). Besides, the adsorption equilibriums of Pb onto SPS microspheres can be achieved within only 1 min and the adsorption kinetics can be fitted by a pseudo-second-order kinetics model. More importantly, because of the micron structure of the SPS microspheres, it could overcome the excessive hydrophilia brought by rich sulphonic acid groups and thereby easily separated, which maintain a good recyclable capacity after five regeneration cycles. With the excellent adsorption ability and reusability, SPS microspheres can efficiently handle the polluted water in a convenience and rapid process, which satisfies the sustainable pollution treatment in heavy metals elimination.
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http://dx.doi.org/10.1080/09593330.2021.1936200DOI Listing
June 2021

Recent Advances in the Prediction of Fouling in Membrane Bioreactors.

Membranes (Basel) 2021 May 24;11(6). Epub 2021 May 24.

Department of Automation, College of Electrical and Information Engineering, Lanzhou University of Technology, Lanzhou 730050, China.

Compared to the traditional activated sludge process, the membrane bioreactor (MBR) has several advantages such as the production of high-quality effluent, generation of low excess sludge, smaller footprint requirements, and ease of automatic control of processes. The MBR has a broader prospect of its applications in wastewater treatment and reuse. However, membrane fouling is the biggest obstacle for its wider application. This paper reviews the techniques available to predict fouling in MBR, discusses the problems associated with predicting fouling status using artificial neural networks and mathematical models, summarizes the current state of fouling prediction techniques, and looks into the trends in their development.
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http://dx.doi.org/10.3390/membranes11060381DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8225185PMC
May 2021

Mine Vegetation Identification via Ecological Monitoring and Deep Belief Network.

Plants (Basel) 2021 May 30;10(6). Epub 2021 May 30.

School of Environmental Studies, China University of Geosciences, Wuhan 430074, China.

Based on the characteristics of remote sensing images of mine vegetation, this research studied the application of deep belief network model in mine vegetation identification. Through vegetation identification and classification, the ecological environment index of mining area was determined according to the analysis of vegetation and coverage. Deep learning algorithm is adopted to improve the depth study, the vegetation coverage in the analysis was studied. Parameters and parameter values were selected for identification by establishing the optimal experimental design. The experimental results were compared with remote sensing images to determine the accuracy of deep learning identification and the effectiveness of the algorithm. When the sample size is 2,000,000 pixels, through repeated tests and classification effect comparison, the optimal parameter setting suitable for mine vegetation identification is obtained. Parameter setting: the number of network layers is 3 layers; the number of hidden layer neurons is 60. The learning rate is 0.01 and the number of iterations is 2. The average recognition rate of vegetation coverage was 95.95%, outperforming some other models, and the accuracy rate of kappa coefficient was 0.95, which can accurately reflect the vegetation coverage. The clearer the satellite image is, the more accurate the recognition result is, and the accuracy is closer to 100%. The identification of vegetation coverage has important guiding significance for determining the area and area of ecological restoration.
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http://dx.doi.org/10.3390/plants10061099DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8228051PMC
May 2021

Endothelial Exosome Plays a Functional Role during Rickettsial Infection.

mBio 2021 05 11;12(3). Epub 2021 May 11.

Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA

Spotted fever group rickettsioses (SFRs) are devastating human infections. Vascular endothelial cells (ECs) are the primary targets of rickettsial infection. Edema resulting from EC barrier dysfunction occurs in the brain and lungs in most cases of lethal SFR, but the underlying mechanisms remain unclear. The aim of the study was to explore the potential role of -infected, EC-derived exosomes (Exos) during infection. Using size exclusion chromatography (SEC), we purified Exos from conditioned, filtered, bacterium-free media collected from -infected human umbilical vein ECs (HUVECs) (-ECExos) and plasma of - or -infected mice (-plsExos). We observed that rickettsial infection increased the release of heterogeneous plsExos, but endothelial exosomal size, morphology, and production were not significantly altered following infection. Compared to normal plsExos and ECExos, both -plsExos and -ECExos induced dysfunction of recipient normal brain microvascular ECs (BMECs). The effect of -plsExos on mouse recipient BMEC barrier function is dose dependent. The effect of -ECExos on human recipient BMEC barrier function is dependent on the exosomal RNA cargo. Next-generation sequencing analysis and stem-loop quantitative reverse transcription-PCR (RT-qPCR) validation revealed that rickettsial infection triggered the selective enrichment of endothelial exosomal mir-23a and mir-30b, which potentially target the endothelial barrier. To our knowledge, this is the first report on the functional role of extracellular vesicles following infection by obligately intracellular bacteria. Spotted fever group rickettsioses are devastating human infections. Vascular endothelial cells are the primary targets of infection. Edema resulting from endothelial barrier dysfunction occurs in the brain and lungs in most cases of lethal rickettsioses, but the underlying mechanisms remain unclear. The aim of the study was to explore the potential role of -infected, endothelial cell-derived exosomes during infection. We observed that rickettsial infection increased the release of heterogeneous plasma Exos, but endothelial exosomal size, morphology, and production were not significantly altered following infection. -infected, endothelial cell-derived exosomes induced dysfunction of human recipient normal brain microvascular endothelial cells. The effect is dependent on the exosomal RNA cargo. Next-generation sequencing analysis revealed that rickettsial infection triggered the selective enrichment of endothelial exosomal mir-23a and mir-30b, which potentially target the endothelial barrier. To our knowledge, this is the first report on the functional role of extracellular vesicles following infection by obligately intracellular bacteria.
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http://dx.doi.org/10.1128/mBio.00769-21DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8262936PMC
May 2021

Cell-Type Apoptosis in Lung during SARS-CoV-2 Infection.

Pathogens 2021 Apr 23;10(5). Epub 2021 Apr 23.

Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA.

The SARS-CoV-2 pandemic has inspired renewed interest in understanding the fundamental pathology of acute respiratory distress syndrome (ARDS) following infection. However, the pathogenesis of ARDS following SRAS-CoV-2 infection remains largely unknown. In the present study, we examined apoptosis in postmortem lung sections from COVID-19 patients and in lung tissues from a non-human primate model of SARS-CoV-2 infection, in a cell-type manner, including type 1 and 2 alveolar cells and vascular endothelial cells (ECs), macrophages, and T cells. Multiple-target immunofluorescence assays and Western blotting suggest both intrinsic and extrinsic apoptotic pathways are activated during SARS-CoV-2 infection. Furthermore, we observed that SARS-CoV-2 fails to induce apoptosis in human bronchial epithelial cells (i.e., BEAS2B cells) and primary human umbilical vein endothelial cells (HUVECs), which are refractory to SARS-CoV-2 infection. However, infection of co-cultured Vero cells and HUVECs or Vero cells and BEAS2B cells with SARS-CoV-2 induced apoptosis in both Vero cells and HUVECs/BEAS2B cells but did not alter the permissiveness of HUVECs or BEAS2B cells to the virus. Post-exposure treatment of the co-culture of Vero cells and HUVECs with a novel non-cyclic nucleotide small molecule EPAC1-specific activator reduced apoptosis in HUVECs. These findings may help to delineate a novel insight into the pathogenesis of ARDS following SARS-CoV-2 infection.
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http://dx.doi.org/10.3390/pathogens10050509DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8145065PMC
April 2021

Cell-type apoptosis in lung during SARS-CoV-2 infection.

bioRxiv 2020 Dec 24. Epub 2020 Dec 24.

The SARS-CoV-2 pandemic has inspired renewed interest in understanding the fundamental pathology of acute respiratory distress syndrome (ARDS) following infection because fatal COVID-19 cases are commonly linked to respiratory failure due to ARDS. The pathologic alteration known as diffuse alveolar damage in endothelial and epithelial cells is a critical feature of acute lung injury in ARDS. However, the pathogenesis of ARDS following SRAS-CoV-2 infection remains largely unknown. In the present study, we examined apoptosis in post-mortem lung sections from COVID-19 patients and lung tissues from a non-human primate model of SARS-CoV-2 infection, in a cell-type manner, including type 1 and 2 alveolar cells and vascular endothelial cells (ECs), macrophages, and T cells. Multiple-target immunofluorescence (IF) assays and western blotting suggest both intrinsic and extrinsic apoptotic pathways are activated during SARS-CoV-2 infection. Furthermore, we observed that SARS-CoV-2 fails to induce apoptosis in human bronchial epithelial cells (i.e., BEAS2B cells) and primary human umbilical vein endothelial cells (HUVECs), which are refractory to SARS-CoV-2 infection. However, infection of co-cultured Vero cells and HUVECs or Vero cells and BEAS2B cells with SARS-CoV-2 induced apoptosis in both Vero cells and HUVECs/BEAS2B cells, but did not alter the permissiveness of HUVECs or BEAS2B cells to the virus. Post-exposure treatment of the co-culture of Vero cells and HUVECs with an EPAC1-specific activator ameliorated apoptosis in HUVECs. These findings may help to delineate a novel insight into the pathogenesis of ARDS following SARS-CoV-2 infection.
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http://dx.doi.org/10.1101/2020.12.23.424254DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781315PMC
December 2020

A sequence embedding method for enzyme optimal condition analysis.

BMC Bioinformatics 2020 Nov 10;21(1):512. Epub 2020 Nov 10.

School of Software, Shandong University, Shunhua Road, Jinan, 250101, China.

Background: An enzyme activity is influenced by the external environment. It is important to have an enzyme remain high activity in a specific condition. A usual way is to first determine the optimal condition of an enzyme by either the gradient test or by tertiary structure, and then to use protein engineering to mutate a wild type enzyme for a higher activity in an expected condition.

Results: In this paper, we investigate the optimal condition of an enzyme by directly analyzing the sequence. We propose an embedding method to represent the amino acids and the structural information as vectors in the latent space. These vectors contain information about the correlations between amino acids and sites in the aligned amino acid sequences, as well as the correlation with the optimal condition. We crawled and processed the amino acid sequences in the glycoside hydrolase GH11 family, and got 125 amino acid sequences with optimal pH condition. We used probabilistic approximation method to implement the embedding learning method on these samples. Based on these embedding vectors, we design a computational score to determine which one has a better optimal condition for two given amino acid sequences and achieves the accuracy 80% on the test proteins in the same family. We also give the mutation suggestion such that it has a higher activity in an expected environment, which is consistent with the previously professional wet experiments and analysis.

Conclusion: A new computational method is proposed for the sequence based on the enzyme optimal condition analysis. Compared with the traditional process that involves a lot of wet experiments and requires multiple mutations, this method can give recommendations on the direction and location of amino acid substitution with reference significance for an expected condition in an efficient and effective way.
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http://dx.doi.org/10.1186/s12859-020-03851-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7653822PMC
November 2020

Effects of seasonal ambient heat stress on expression of microRNAs in the mammary gland of Holstein cows.

Int J Biometeorol 2021 Feb 29;65(2):235-246. Epub 2020 Oct 29.

College of Animal Science and Technology, Anhui Agricultural University, Hefei, 230036, People's Republic of China.

This study was conducted to assess the link of miRNA expressions in cow's mammary gland undergoing heat stress. Twelve Holstein cows were allocated either to undergo heat stress (HS) or remain in a thermoneutral environment (non-heat stress, NS), respectively. The experiment with HS cows was carried out in August, and the experiment with NS cows was done in November. After a month, three cows from each group were slaughtered, and mammary gland samples were obtained, and then miRNA were extracted from the samples for later sequencing. From the miRNA-seq, we obtained a total of 124 differentially expressed miRNAs in HS and NS cows' mammary gland. The differentially expressed miRNA could be predicted to influence multiple target genes. The target interleukin-1 (IL-1), which play a role in regulating the function of mammary gland in dairy cows, could be affected by bta-let-7c, bta-let-7e, bta-miR-181d, bta-miR-452, and bta-miR-31. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that mitogen-activated protein kinase (MAPK) pathway plays an important role in the mammary glands of dairy cows and bta-miR-25 and bta-miR-382 may influence MAPK pathway through c-Jun N-terminal kinase (JNK) gene to affect the function of mammary gland in HS cows. In conclusion, this study characterized expression profile of miRNAs in the Holstein cows' mammary gland under summer heat stress or not. We observed miRNA expression during heat stress, which was significantly different from non-heat stress states. A comprehensive analysis of the miRNA's expression will be helpful to further study the link of miRNAs with mechanisms regulating heat stress in the cow mammary gland.
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http://dx.doi.org/10.1007/s00484-020-02025-5DOI Listing
February 2021

Synthetic Bilayers on Mica from Self-Assembly of Hydrogen-Bonded Triazines.

Langmuir 2020 Nov 27;36(44):13301-13311. Epub 2020 Oct 27.

Mark Wainwright Analytical Centre, University of New South Wales, Room G61, Chemical Sciences Building (F10), Kensington, NSW 2052, Australia.

This study describes organic thin films prepared under a range of conditions from a model series of bis--alkyl chloro-triazines functionalized with short alkyl chains from ethyl to hexyl. The pure films were characterized using atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). When cast on mica, these compounds assemble as crystalline sheets made up of a synthetic bilayer along the crystallographic -plane with an internal hydrogen-bonded domain between external alkyl chains. These micron-scale surfaces stack along the -axis, and increasing the alkyl chain length results in changes to the crystal morphology from needles to nanoscale plates. Thicker films produce nanoscale, pyramidal stacks of bilayers. Compared to atomically flat mica, a rougher, unetched silicon substrate produced irregular domains in the secondary bilayer. Films of mixtures comprising the ethyl derivative with butyl, pentyl, or hexyl derivative were imaged using time-of-flight secondary-ion mass spectrometry (ToF-SIMS) that indicated a trend toward a constant stoichiometry with increasing alkyl chain length. AFM of mixed films on mica showed single bilayers of height <2 nm, with an acceptable correlation to the XRD measurements, supporting a constant stoichiometry. These materials permit easy modification of mica to a micron-scale, atomically flat hydrophobic surface, and the use of mixtures with different alkyl chain lengths suggests a method to improve the quality of functional organic thin films.
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http://dx.doi.org/10.1021/acs.langmuir.0c02377DOI Listing
November 2020

Simulations of octapeptin-outer membrane interactions reveal conformational flexibility is linked to antimicrobial potency.

J Biol Chem 2020 11 10;295(47):15902-15912. Epub 2020 Sep 10.

Biomedicine Discovery Institute, Infection & Immunity Program, Department of Microbiology, Monash University, Melbourne, Victoria, Australia. Electronic address:

The octapeptins are lipopeptide antibiotics that are structurally similar to polymyxins yet retain activity against polymyxin-resistant Gram-negative pathogens, suggesting they might be used to treat recalcitrant infections. However, the basis of their unique activity is unclear because of the difficulty in generating high-resolution experimental data of the interaction of antimicrobial peptides with lipid membranes. To elucidate these structure-activity relationships, we employed all-atom molecular dynamics simulations with umbrella sampling to investigate the conformational and energetic landscape of octapeptins interacting with bacterial outer membrane (OM). Specifically, we examined the interaction of octapeptin C4 and FADDI-115, lacking a single hydroxyl group compared with octapeptin C4, with the lipid A-phosphoethanolamine modified OM of Octapeptin C4 and FADDI-115 both penetrated into the OM hydrophobic center but experienced different conformational transitions from an unfolded to a folded state that was highly dependent on the structural flexibility of their respective N-terminal fatty acyl groups. The additional hydroxyl group present in the fatty acyl group of octapeptin C4 resulted in the molecule becoming trapped in a semifolded state, leading to a higher free energy barrier for OM penetration. The free energy barrier for the translocation through the OM hydrophobic layer was ∼72 kcal/mol for octapeptin C4 and 62 kcal/mol for FADDI-115. Our results help to explain the lower antimicrobial activity previously observed for octapeptin C4 compared with FADDI-115 and more broadly improve our understanding of the structure-function relationships of octapeptins. These findings may facilitate the discovery of next-generation octapeptins against polymyxin-resistant Gram-negative 'superbugs.'
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http://dx.doi.org/10.1074/jbc.RA120.014856DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7681018PMC
November 2020

Molecular dynamics simulations informed by membrane lipidomics reveal the structure-interaction relationship of polymyxins with the lipid A-based outer membrane of Acinetobacter baumannii.

J Antimicrob Chemother 2020 12;75(12):3534-3543

Biomedicine Discovery Institute, Infection & Immunity Program and Department of Microbiology, Monash University, Melbourne, Australia.

Background: MDR bacteria represent an urgent threat to human health globally. Polymyxins are a last-line therapy against life-threatening Gram-negative 'superbugs', including Acinetobacter baumannii. Polymyxins exert antimicrobial activity primarily via permeabilizing the bacterial outer membrane (OM); however, the mechanism of interaction between polymyxins and the OM remains unclear at the atomic level.

Methods: We constructed a lipid A-based OM model of A. baumannii using quantitative membrane lipidomics data and employed all-atom molecular dynamics simulations with umbrella sampling techniques to elucidate the structure-interaction relationship and thermodynamics governing the penetration of polymyxins [B1 and E1 (i.e. colistin A) representing the two clinically used polymyxins] into the OM.

Results: Polymyxin B1 and colistin A bound to the A. baumannii OM by the initial electrostatic interactions between the Dab residues of polymyxins and the phosphates of lipid A, competitively displacing the cations from the headgroup region of the OM. Both polymyxin B1 and colistin A formed a unique folded conformation upon approaching the hydrophobic centre of the OM, consistent with previous experimental observations. Polymyxin penetration induced reorientation of the headgroups of the OM lipids near the penetration site and caused local membrane disorganization, thereby significantly increasing membrane permeability and promoting the subsequent penetration of polymyxin molecules into the OM and periplasmic space.

Conclusions: The thermodynamics governing the penetration of polymyxins through the outer leaflet of the A. baumannii OM were examined and novel structure-interaction relationship information was obtained at the atomic and membrane level. Our findings will facilitate the discovery of novel polymyxins against MDR Gram-negative pathogens.
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http://dx.doi.org/10.1093/jac/dkaa376DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7662177PMC
December 2020

EPAC regulates von Willebrand factor secretion from endothelial cells in a PI3K/eNOS-dependent manner during inflammation.

bioRxiv 2020 Sep 4. Epub 2020 Sep 4.

Coagulopathy is associated with both inflammation and infection, including infection with the novel SARS-CoV-2 (COVID-19). Endothelial cells (ECs) fine tune hemostasis via cAMP-mediated secretion of von Willebrand factor (vWF), which promote the process of clot formation. The e xchange p rotein directly a ctivated by c AMP (EPAC) is a ubiquitously expressed intracellular cAMP receptor that plays a key role in stabilizing ECs and suppressing inflammation. To assess whether EPAC could regulate vWF release during inflammation, we utilized our -null mouse model and revealed an increased secretion of vWF in endotoxemic mice in the absence of the EPAC1 gene. Pharmacological inhibition of EPAC1 mimicked the -/- phenotype. EPAC1 regulated TNFα-triggered vWF secretion from human umbilical vein endothelial cells (HUVECs) in a phosphoinositide 3-kinases (PI3K)/endothelial nitric oxide synthase (eNOS)-dependent manner. Furthermore, EPAC1 activation reduced inflammation-triggered vWF release, both and . Our data delineate a novel regulatory role of EPAC1 in vWF secretion and shed light on potential development of new strategies to controlling thrombosis during inflammation.

Key Point: PI3K/eNOS pathway-mediated, inflammation-triggered vWF secretion is the target of the pharmacological manipulation of the cAMP-EPAC system.
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http://dx.doi.org/10.1101/2020.09.04.282806DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7480044PMC
September 2020

Outer Membranes of Polymyxin-Resistant with Phosphoethanolamine-Modified Lipid A and Lipopolysaccharide Loss Display Different Atomic-Scale Interactions with Polymyxins.

ACS Infect Dis 2020 10 15;6(10):2698-2708. Epub 2020 Sep 15.

Biomedicine Discovery Institute, Infection & Immunity Program, Department of Microbiology, Monash University, Melbourne, VIC 3800, Australia.

Resistance to the last-line polymyxins is increasingly reported in multidrug-resistant Gram-negative pathogens, including , which develops resistance via either lipid A modification (e.g., with phosphoethanolamine [pEtN]) or even lipopolysaccharide (LPS) loss in the outer membrane (OM). Considering these two different mechanisms, quantitative membrane lipidomics data were utilized to develop three OM models representing polymyxin-susceptible and -resistant strains. Through all-atom molecular simulations with enhanced sampling techniques, the effect of lipid A-pEtN modification and LPS loss on the action of colistin (i.e., polymyxin E) was examined for the first time, with a focus on the dynamics and energetics of colistin penetration into these OMs. Lipid A-pEtN modification improved the OM stability, impeding the penetration of colistin into the OM; this differed from the current literature that lipid A-pEtN modification confers resistance by diminishing the initial interaction with polymyxins. In contrast, the LPS deficiency significantly reduced the negative charges on the OM surface, diminishing the binding of colistin. Moreover, both lipid A-pEtN modification and LPS loss also constituted colistin resistance through disturbing the conformational transitions of the colistin molecule. Collectively, atomic-scale interactions between polymyxins and different bacterial OMs are very different and the findings may facilitate the discovery of new-generation polymyxins against Gram-negative 'superbugs'.
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http://dx.doi.org/10.1021/acsinfecdis.0c00330DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7554230PMC
October 2020

Polymyxins Bind to the Cell Surface of Unculturable and Cause Unique Dependent Resistance.

Adv Sci (Weinh) 2020 Aug 8;7(15):2000704. Epub 2020 Jun 8.

Infection & Immunity Program Biomedicine Discovery Institute and Department of Microbiology Monash University Melbourne 3800 Australia.

Multidrug-resistant is a top-priority pathogen globally and polymyxins are a last-line therapy. Polymyxin dependence in (i.e., nonculturable on agar without polymyxins) is a unique and highly-resistant phenotype with a significant potential to cause treatment failure in patients. The present study discovers that a polymyxin-dependent strain possesses mutations in both (lipopolysaccharide biosynthesis) and (reactive oxygen species scavenging) genes. Correlative multiomics analyses show a significantly remodeled cell envelope and remarkably abundant phosphatidylglycerol in the outer membrane (OM). Molecular dynamics simulations and quantitative membrane lipidomics reveal that polymyxin-dependent growth emerges only when the lipopolysaccharide-deficient OM distinctively remodels with ≥ 35% phosphatidylglycerol, and with "patch" binding on the OM by the rigid polymyxin molecules containing strong intramolecular hydrogen bonding. Rather than damaging the OM, polymyxins bind to the phosphatidylglycerol-rich OM and strengthen the membrane integrity, thereby protecting bacteria from external reactive oxygen species. Dependent growth is observed exclusively with polymyxin analogues, indicating a critical role of the specific amino acid sequence of polymyxins in forming unique structures for patch-binding to bacterial OM. Polymyxin dependence is a novel antibiotic resistance mechanism and the current findings highlight the risk of 'invisible' polymyxin-dependent isolates in the evolution of resistance.
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http://dx.doi.org/10.1002/advs.202000704DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7403960PMC
August 2020

Annexin A2 depletion exacerbates the intracerebral microhemorrhage induced by acute rickettsia and Ebola virus infections.

PLoS Negl Trop Dis 2020 07 20;14(7):e0007960. Epub 2020 Jul 20.

Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America.

Intracerebral microhemorrhages (CMHs) are small foci of hemorrhages in the cerebrum. Acute infections induced by some intracellular pathogens, including rickettsia, can result in CMHs. Annexin a2 (ANXA2) has been documented to play a functional role during intracellular bacterial adhesion. Here we report that ANXA2-knockout (KO) mice are more susceptible to CMHs in response to rickettsia and Ebola virus infections, suggesting an essential role of ANXA2 in protecting vascular integrity during these intracellular pathogen infections. Proteomic analysis via mass spectrometry of whole brain lysates and brain-derived endosomes from ANXA2-KO and wild-type (WT) mice post-infection with R. australis revealed that a variety of significant proteins were differentially expressed, and the follow-up function enrichment analysis had identified several relevant cell-cell junction functions. Immunohistology study confirmed that both infected WT and infected ANXA2-KO mice were subjected to adherens junctional protein (VE-cadherin) damages. However, key blood-brain barrier (BBB) components, tight junctional proteins ZO-1 and occludin, were disorganized in the brains from R. australis-infected ANXA2-KO mice, but not those of infected WT mice. Similar ANXA2-KO dependent CMHs and fragments of ZO-1 and occludin were also observed in Ebola virus-infected ANXA2-KO mice, but not found in infected WT mice. Overall, our study revealed a novel role of ANXA2 in the formation of CMHs during R. australis and Ebola virus infections; and the underlying mechanism is relevant to the role of ANXA2-regulated tight junctions and its role in stabilizing the BBB in these deadly infections.
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http://dx.doi.org/10.1371/journal.pntd.0007960DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7392349PMC
July 2020

Structure-Interaction Relationship of Polymyxins with the Membrane of Human Kidney Proximal Tubular Cells.

ACS Infect Dis 2020 08 17;6(8):2110-2119. Epub 2020 Jul 17.

Biomedicine Discovery Institute, Infection & Immunity Program and Department of Microbiology, Monash University, Clayton, Melbourne, Victoria 3800, Australia.

Multidrug-resistant Gram-negative bacteria are a serious global threat to human health. Polymyxins are increasingly used in patients as a last-line therapy to treat infections caused by these life-threatening 'superbugs'. Unfortunately, polymyxin-induced nephrotoxicity is the major dose-limiting factor and understanding its mechanism is crucial for the development of novel, safer polymyxins. Here, we undertook the first all-atom molecular dynamics simulations of the interaction between four naturally occurring polymyxins A, B, M and colistin A (representative structural variations of the polymyxin core structure) and the membrane of human kidney proximal tubular cells. All polymyxins inserted spontaneously into the hydrophobic region of the membrane where they were retained, although their insertion abilities varied. Polymyxin A completely penetrated into the hydrophobic region of the membrane with a unique folded conformation, whereas the other three polymyxins only inserted their fatty acyl tails into this region. Furthermore, local membrane defects and increased water penetration were induced by each polymyxin, which may represent the initial stage of cellular membrane damage. Finally, the structure-interaction relationship of polymyxins was investigated based on atomic interactions at the cell membrane level. The hydrophobicity at positions 6/7 and stereochemistry at position 3 regulated the interactions of polymyxins with the cell membrane. Collectively, our results provide new mechanistic insights into polymyxin-induced nephrotoxicity at the atomic level and will facilitate the development of new-generation polymyxins.
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http://dx.doi.org/10.1021/acsinfecdis.0c00190DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7485602PMC
August 2020

Combination BET Family Protein and HDAC Inhibition Synergistically Elicits Chondrosarcoma Cell Apoptosis Through RAD51-Related DNA Damage Repair.

Cancer Manag Res 2020 10;12:4429-4439. Epub 2020 Jun 10.

Department of Orthopedics, The Third Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, People's Republic of China.

Background: Chondrosarcoma is the second-most common type of bone tumor and has inherent resistance to conventional chemotherapy. Present study aimed to explore the therapeutic effect and specific mechanism(s) of combination BET family protein and HDAC inhibition in chondrosarcoma.

Methods: Two chondrosarcoma cells were treated with BET family protein inhibitor (JQ1) and histone deacetylase inhibitors (HDACIs) (vorinostat/SAHA or panobinostat/PANO) separately or in combination; then, the cell viability was determined by Cell Counting Kit-8 (CCK-8) assay, and the combination index (CI) was calculated by the Chou method; cell proliferation was evaluated by 5-ethynyl-2'-deoxyuridine (EdU) incorporation and colony formation assay; cell apoptosis and reactive oxygen species (ROS) level were determined by flow cytometry; protein expressions of caspase-3, Bcl-XL, Bcl-2, γ-H2AX, and RAD51 were examined by Immunoblotting; DNA damage was determined by comet assay; RAD51 and γ-H2AX foci were observed by immunofluorescence.

Results: Combined treatment with JQ1 and SAHA or PANO synergistically suppressed the growth and colony formation ability of the chondrosarcoma cells. Combined BET and HDAC inhibition also significantly elevated the ROS level, followed by the activation of cleaved-caspase-3, and the downregulation of Bcl-2 and Bcl-XL. Mechanistically, combination treatment with JQ1 and SAHA caused numerous DNA double-strand breaks (DSBs), as evidenced by the comet assay. The increase in γ-H2AX expression and foci formation also consistently indicated the accumulation of DNA damage upon cotreatment with JQ1 and SAHA. Furthermore, RAD51, a key protein of homologous recombination (HR) DNA repair, was found to be profoundly suppressed. In contrast, ectopic expression of RAD51 partially rescued SW 1353 cell apoptosis by inhibiting the expression of cleaved-caspase-3.

Conclusion: Taken together, our results disclose that BET and HDAC inhibition synergistically inhibit cell growth and induce cell apoptosis through a mechanism that involves the suppression of RAD51-related HR DNA repair in chondrosarcoma cells.
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http://dx.doi.org/10.2147/CMAR.S254412DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7294047PMC
June 2020

Increased talin-vinculin spatial proximities in livers in response to spotted fever group rickettsial and Ebola virus infections.

Lab Invest 2020 08 1;100(8):1030-1041. Epub 2020 Apr 1.

Department of Pathology, University of Texas Medical Branch, Galveston, TX, 77555, USA.

Talin and vinculin, both actin-cytoskeleton-related proteins, have been documented to participate in establishing bacterial infections, respectively, as the adapter protein to mediate cytoskeleton-driven dynamics of the plasma membrane. However, little is known regarding the potential role of the talin-vinculin complex during spotted fever group rickettsial and Ebola virus infections, two dreadful infectious diseases in humans. Many functional properties of proteins are determined by their participation in protein-protein complexes, in a temporal and/or spatial manner. To resolve the limitation of application in using mouse primary antibodies on archival, multiple formalin-fixed mouse tissue samples, which were collected from experiments requiring high biocontainment, we developed a practical strategic proximity ligation assay (PLA) capable of employing one primary antibody raised in mouse to probe talin-vinculin spatial proximal complex in mouse tissue. We observed an increase of talin-vinculin spatial proximities in the livers of spotted fever Rickettsia australis or Ebola virus-infected mice when compared with mock mice. Furthermore, using EPAC1-knockout mice, we found that deletion of EPAC1 could suppress the formation of spatial proximal complex of talin-vinculin in rickettsial infections. In addition, we observed increased colocalization between spatial proximity of talin-vinculin and filamentous actin-specific phalloidin staining in single survival mouse from an ordinarily lethal dose of rickettsial or Ebola virus infection. These findings may help to delineate a fresh insight into the mechanisms underlying liver specific pathogenesis during infection with spotted fever rickettsia or Ebola virus in the mouse model.
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http://dx.doi.org/10.1038/s41374-020-0420-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7111589PMC
August 2020

The micro-photoconductivity spectroscopy with the spectral capability extended to mid-infrared.

Rev Sci Instrum 2020 Jan;91(1):013105

Physics Department, Shanghai University, Shanghai 200444, China.

A microphotoconductivity (μPC) spectroscopy is developed with an ordinary monochromator and halogen and SiN globar lamps. The instrument may cover a wide spectral range from visible to mid-infrared. For the μ-PC instrumentation, the improvement of signal-to-noise ratio is a crucial issue. We demonstrate that the employment of the Wheatstone bridge provides an effective solution. The instrument has been successfully applied to the narrow bandgap semiconductors InGaAs and HgCdTe, which show the optical band edges at the wavelengths of 2.35 µm and 5.0 µm at 82 K, respectively. The minimization of the light spot is influenced by the intensity of the light source, and the 45 W globar allows the performance of μPC with a light spot of 30 µm diameter for the spectral range of 2.0-3.5 µm, whereas the light spot of 60 µm diameter is necessarily used for the spectral range around 5.0 µm.
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http://dx.doi.org/10.1063/1.5128855DOI Listing
January 2020

Direct electrochemistry of bacterial surface displayed cytokinin oxidase and its application in the sensitive electrochemical detection of cytokinins.

Bioelectrochemistry 2019 Dec 25;130:107336. Epub 2019 Jul 25.

Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, Key Lab for Biotechnology of National Commission for Nationalities, College of Life Science, South Central University for Nationalities, Wuhan 430074, PR China. Electronic address:

Cytokinin oxidase from Nipponbare (OsCKX4) was successfully displayed on the surface of E. coli cells by an ice nucleation protein from Pseudomonas borealis DL7 as an anchoring motif and a maltodextrin-binding protein(MBP) from E. coli as a solubility enhancer. The OsCKX4-displayed bacteria can be directly immobilized onto an electrode to selectively detect cytokinins, thus eliminating the need for enzyme extraction and purification. Direct electrochemistry of the cofactor FADH in OsCKX4 has been achieved on an edge-plane pyrolytic graphite electrode (PGE) with a formal potential (E) of -0.45 V at pH 7.0 in phosphate buffer. With the addition of isopentenyladenine, the reduction peak current for FADH decreased, and the oxidative peak current increased gradually. Therefore, a bacteria-OsCKX4-modified PGE has been developed for the detection of isopentenyladenine with a linear range of 1.0-11.0 μM and a lower limit of detection of 0.7 μM (S/N = 3). Slight interference was observed in the presence of other phytohormones, including brassinosteroid, abscisic acid, methylene jasminate and gibberellin. The proposed bacterial biosensor is stable, specific and simple and has great potential for applications that require the detection of cytokinins.
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http://dx.doi.org/10.1016/j.bioelechem.2019.107336DOI Listing
December 2019
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