Detection of MMP activity in living cells by a genetically encoded surface-displayed FRET sensor

AbstractMatrix metalloproteinases (MMPs) are secretory endopeptidases. They have been associated with invasion by cancer-cell and metastasis. Previous studies have demonstrated that proteolytic activity could be detected using fluorescence resonance energy transfer (FRET) with mutants of GFP. To monitor MMP activity, we constructed vectors that encoded a MMP Substrate Site (MSS) between YFP and CFP. In vitro, YFP–MSS–CFP can be used to detect MMP activity and 1,10-phenathroline inhibition of MMP activity. In living cells, MMPs are secreted proteins and act outside of the cell, and therefore YFP–MSS–CFPdisplay was anchored on the cellular surface to detect extracellular MMP. A pDisplay-YC vector expressing the YFP–MSS–CFPdisplay on the cellular surface was transfected into MCF-7 cells that expressed low levels of MMP. Efficient transfer of energy from excited CFP to YFP within the YFP–MSS–CFPdisplay molecule was observed, and real-time FRET was declined when MCF-7 was incubated with MMP2. However, no such transfer of energy was detected in the YFP–MSS–CFPdisplay expressing MDA-MB 435s cells, in which high secretory MMP2 were expressed. The FRET sensor YFP–MSS–CFPdisplay can sensitively and reliably monitor MMP activation in living cells and can be used for high-throughput screening of MMP inhibitors for anti-cancer treatments

Quantitative systematic review of the transformational leadership style as a driver of nurses' organisational commitment

Aims To explore the association between nurses' perceptions of their nurse manager's transformational leadership style and nurses' organisational commitment. Design Narrative systematic review. Data Sources The CINAHL Complete, MEDLINE, PubMed, Business Source Complete, Cochrane Library, along with OpenGrey t were systematically searched for observational studies written in English, between January 2009 and December 2020. Review Methods This systematic review is based on the guidelines of the Cochrane Handbook, and PRISMA-P. Two reviewers independently selected studies. The quality of evidence was assessed using the Joanna Briggs Institute (JBI) Critical Appraisal Tool for Cross-Sectional Studies. Results Seven cross-sectional studies with 2885 participants were included. Six studies reported that the transformational leadership style was positively related to nurses' organisational commitment, and the remaining study reported a negative association. Conclusions Six studies were found that the transformational leadership style is a driver of nurses' organisational commitment. Only one study reported that transformational leadership style negatively associated with acute care nurses' organisational commitment. However, the negative finding is less valid, as the study data indicates that the nurse managers' ineffective transformational leadership style in the acute care unit or the culture influence, which may have influenced the results. Impacts It provides the guideline, recommendation, and important evidence to support nursing managers adopting the transformational leadership style to promote nurse retention helping to alleviate the nursing shortage. This is beneficial to the well-being of the nurse. Meanwhile, this can help the health organisation reducing the cost of nurses' turnover and recruiting new nurses. It is also good for address future ageing population healthcare problem in the long term

Robust passivity and passification of stochastic fuzzy time-delay systems

The official published version can be obtained from the link below.In this paper, the passivity and passification problems are investigated for a class of uncertain stochastic fuzzy systems with time-varying delays. The fuzzy system is based on the Takagi–Sugeno (T–S) model that is often used to represent the complex nonlinear systems in terms of fuzzy sets and fuzzy reasoning. To reflect more realistic dynamical behaviors of the system, both the parameter uncertainties and the stochastic disturbances are considered, where the parameter uncertainties enter into all the system matrices and the stochastic disturbances are given in the form of a Brownian motion. We first propose the definition of robust passivity in the sense of expectation. Then, by utilizing the Lyapunov functional method, the Itô differential rule and the matrix analysis techniques, we establish several sufficient criteria such that, for all admissible parameter uncertainties and stochastic disturbances, the closed-loop stochastic fuzzy time-delay system is robustly passive in the sense of expectation. The derived criteria, which are either delay-independent or delay-dependent, are expressed in terms of linear matrix inequalities (LMIs) that can be easily checked by using the standard numerical software. Illustrative examples are presented to demonstrate the effectiveness and usefulness of the proposed results.This work was supported by the Teaching and Research Fund for Excellent Young Teachers at Southeast University of China, the Specialized Research Fund for the Doctoral Program of Higher Education for New Teachers 200802861044, the National Natural Science Foundation of China under Grant 60804028 and the Royal Society of the United Kingdom

Vertical distribution and influencing factors of deep soil organic carbon in a typical subtropical agricultural watershed

Acknowledgement This study was financially supported by the National Key Research and Development Program of China (2018YFE0107000), the National Natural Science Foundation of China (42107334), the Second Tibetan Plateau Scientific Expedition and Research Program (2019QZKK0306), and the China Postdoctoral Science Foundation (2021TQ0337, 2021M703305). Special thanks go to our colleagues of Soils in Time and Space team for their help during field survey and laboratory analysis.Peer reviewe

Simvastatin Blocks Blood-Brain Barrier Disruptions Induced by Elevated Cholesterol Both In Vivo and In Vitro

Background. Hypercholesterolemia and disruptions of the blood brain barrier (BBB) have been implicated as underlying mechanisms in the pathogenesis of Alzheimer's disease (AD). Simvastatin therapy may be of benefit in treating AD; however, its mechanism has not been yet fully understood. Objective. To explore whether simvastatin could block disruption of BBB induced by cholesterol both in vivo and in vitro. Methods. New Zealand rabbits were fed cholesterol-enriched diet with or without simvastatin. Total cholesterol of serum and brain was measured. BBB dysfunction was evaluated. To further test the results in vivo, rat brain microvascular endothelial cells (RBMECs) were stimulated with cholesterol in the presence/absence of simvastatin in vitro. BBB disruption was evaluated. Results. Simvastatin blocked cholesterol-rich diet induced leakage of Evan's blue dye. Cholesterol content in the serum was affected by simvastatin, but not brain cholesterol. Simvastatin blocked high-cholesterol medium-induced decrease in TEER and increase in transendothelial FITC-labeled BSA Passage in RBMECs. Conclusions. The present study firstly shows that simvastatin improves disturbed BBB function both in vivo and in vitro. Our data provide that simvastatin may be useful for attenuating disturbed BBB mediated by hypercholesterolemia

Release Characteristics, Mucus Permeability, and Cellular Uptake of Glabridin/Hydroxypropyl-β-Cyclodextrin Inclusion Complex

GLD/HP-β-CD inclusion complexes were prepared by encapsulating glabridin (GLD) with hydroxypropyl (HP) and β-cyclodextrin (β-CD) to improve the solubility of GLD in water. The morphology, the existing form of GLD, the interaction between GLD and HP-β-CD and the spatial conformation of the inclusion complexes were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and molecular docking, respectively. Furthermore, the dissolution and release characteristics of GLD/HP-β-CD inclusion complexes were investigated in vitro in simulated gastric and intestinal fluids. The permeability of GLD/HP-β-CD through the mucus layer was studied using the Transwell method, and the spatial conformation and interaction of GLD and mucins were investigated by molecular docking. The small intestinal uptake of GLD in GLD/HP-β-CD inclusion complexes was studied using Caco-2 cells, and the effect of the vector HP-β-CD on GLD uptake and the possible underlying mechanism were investigated. The results showed that the encapsulation efficiency and drug loading of GLD in GLD/HP-β-CD were 90.03% and 14.51%, respectively, and HP-β-CD could significantly increase the saturation solubility of GLD in water to 109.36 mg/mL. SEM showed that the GLD/HP-β-CD solid inclusion complexes were irregularly flake-shaped. DSC showed that GLD in the GLD/HP-β-CD inclusion complexes was present in an amorphous non-crystalline form. FTIR and DSC fully demonstrated that HP-β-CD encapsulated GLD in the cavity to form an inclusion complex. Molecular docking showed that GLD molecules were able to completely enter the cavity of HP-β-CD, the optimal binding energy between GLD and HP-β-CD was −7.37 kcal/mol, and the interaction between molecules was mainly maintained by van der Waals force. Compared with free GLD, the cumulative dissolution rate of GLD/HP-β-CD at 1 h in simulated gastric and intestinal fluids was increased by 15.75 and 12.4 folds, respectively, and the total cumulative release rate at 24 h in simulated gastric and intestinal fluids was increased by 54 folds. The apparent permeability coefficient through the mucus layer was increased from 9.24 × 10-9 to 1.43 × 10-5 cm/s. Molecular docking showed a strong interaction between GLD and the mucin MUC2, and the uptake by Caco-2 cells was increased from 0.039 to 0.349 mg/g. The present study shows that GLD/HP-β-CD complexes can significantly increase the dissolution and release of GLD, and greatly improve the permeability of GLD through the mucus layer of the intestinal epithelial surface and the uptake of GLD by intestinal epithelial cells, thereby having the potential to enhance GLD absorption and improve the bioavailability of GLD

An intelligent fault diagnosis method for PV arrays based on an improved rotation forest algorithm

With the exponential growth of global photovoltaic (PV) power capacity, it is essential to monitor, detect and diagnose the faults in PV arrays for optimal operation. This paper presents an improved rotation forest (RoF) algorithm classifiers ensemble hybridized with extreme learning machine (ELM) for fault diagnosis of PV arrays, which mainly consists of feature selection and classification. In the feature selection step, all the attributes are ranked by the ReliefF algorithm and the top-ranked attributes are chosen to create the new training data subset. In the classification step, the base classifier decision tree of the RoF is replaced by the extreme learning machine to form a new hybrid RoF-ELM ensemble classifier. In the RoF-ELM algorithm, the feature space is first split into several subspaces and the best number of feature subsets is found through the traversal search method. Then, the bootstrap algorithm is employed to carry out bootstrap resampling for each feature subspace, and the principal component analysis (PCA) is then used to transform the resampled samples. Finally, the ELM base classifier is exploited to build each classification model and the final decision is determined by the simple voting approach. By combining the RoF ensemble method with the ELM classifier, the proposed RoF-ELM algorithm not only overcomes the overfitting problem of the basic RoF algorithm, but also improves the generalization ability of the basic ELM. In order to experimentally verify the proposed approach, different types and levels of faults have been created in a laboratory small scale grid-connected PV power system to obtain the fault data samples. Experimental results demonstrate that the RoF-ELM can achieve higher diagnosis accuracy and reliability compared to the basic RoF and ELM algorithms

Quantitatively assessing ecological stress of urbanization on natural ecosystems by using a landscape-adjacency index

Urban spatial expansion poses a threat to regional ecosystems and biodiversity directly through altering the size, shape, and interconnectivity of natural landscapes. Monitoring urban spatial expansion using traditional area-based metrics from remote sensing provides a feasible way to quantify this regional ecological stress. However, variation in landscape-adjacency relationships (i.e., the adjacency between individual landscape classes) caused by urban expansion is often overlooked. In this study, a novel edge-based index (landscape-adjacency index, LAdI) was proposed based on the spatial-adjacency relationship between landscape patches to measure the regional ecological stress of urban expansion on natural landscapes. Taking the entire Yangtze River Delta Urban Agglomerations (YRD) as a study area, we applied the LAdI for individual landscape classes (Vi) and landscape level (LV) to quantitatively assess change over time in the ecological stress of YRD from 1990 to 2015 at two spatial scales: municipal scale and 5 km-grid scale. The results showed that the vulnerable zones (LV ≥ 0.6) were mainly distributed in the north of the YRD, and cultivated land was the most vulnerable natural landscape (Vi ≥ 0.6) at the 5 km-grid scale. The most vulnerable landscape at the municipal scale was cultivated land in 19 of 26 cities in each period, and that in the remaining 7 cities varied at distinct urbanization stages. We used scatter diagrams and Pearson correlation analysis to compare the edge-based LAdI with an area-based index (percent of built-up area, PB) and found that: LV and PB had a significant positive correlation at both the municipal scale and 5 km-grid scale. But there were multiple LVs with different values corresponding to one PB with the same value at the 5 km-grid scale. Both indexes could represent the degree of urban expansion; however, the edge-based metric better quantified ecological stress under different urban-sprawl patterns sharing the same percent of built-up area. As changes in land use affect both the size and edge effect among landscape patches, the area-based PB and the edge-based LAdI should be applied together when assessing the ecological stress caused by urbanization