Concentration-dependent Changes Research Articles

Levetiracetam modulates brain metabolic networks and transcriptomic signatures in the 5XFAD mouse model of Alzheimer's disease.

Subcritical epileptiform activity is associated with impaired cognitive function and is commonly seen in patients with Alzheimer's disease (AD). The anti-convulsant, levetiracetam (LEV), is currently being evaluated in clinical trials for its ability to reduce epileptiform activity and improve cognitive function in AD. The purpose of the current study was to apply pharmacokinetics (PK), network analysis of medical imaging, gene transcriptomics, and PK/PD modeling to a cohort of amyloidogenic mice to establish how LEV restores or drives alterations in the brain networks of mice in a dose-dependent basis using the rigorous preclinical pipeline of the MODEL-AD Preclinical Testing Core. Chronic LEV was administered to 5XFAD mice of both sexes for 3 months based on allometrically scaled clinical dose levels from PK models. Data collection and analysis consisted of a multi-modal approach utilizing 18F-FDG PET/MRI imaging and analysis, transcriptomic analyses, and PK/PD modeling. Pharmacokinetics of LEV showed a sex and dose dependence in Cmax, CL/F, and AUC0-∞, with simulations used to estimate dose regimens. Chronic dosing at 10, 30, and 56 mg/kg, showed 18F-FDG specific regional differences in brain uptake, and in whole brain covariance measures such as clustering coefficient, degree, network density, and connection strength (i.e., positive and negative). In addition, transcriptomic analysis via nanoString showed dose-dependent changes in gene expression in pathways consistent 18F-FDG uptake and network changes, and PK/PD modeling showed a concentration dependence for key genes, but not for network covariance modeling. This study represents the first report detailing the relationships of metabolic covariance and transcriptomic network changes resulting from LEV administration in 5XFAD mice. Overall, our results highlight non-linear kinetics based on dose and sex, where gene expression analysis demonstrated LEV dose- and concentration-dependent changes, along with cerebral metabolism, and/or cerebral homeostatic mechanisms relevant to human AD, which aligned closely with network covariance analysis of 18F-FDG images. Collectively, this study show cases the value of a multimodal connectomic, transcriptomic, and pharmacokinetic approach to further investigate dose dependent relationships in preclinical studies, with translational value toward informing clinical study design.

Sugar-based Cryoprotectants Stabilize Liposomal Vesicles by Exhibiting a Cholesterol-like Effect.

Liposomal vesicles tend to fuse and aggregate during lyophilization. To avoid these events, cryoprotectants are added to the dispersion before lyophilization. Herein, we have compared the effect of three commonly used cryoprotectants (mannitol, MTL; trehalose, THL; and β-cyclodextrin, β-CD) upon structural characteristics of liposomes. The formulation was prepared using ethanol injection method, and cryoprotectants were tested at three dose levels (2, 6, and 10 mM). We have elucidated their effect on soy lecithin (SL) liposomes formulated with and without cholesterol (CHL). Characterizations were performed using scattering, thermal, and spectroscopic techniques. CHL molecules interacted hydrophobically with the SL bilayer. In spite of triggering a noticeable increase in the hydrodynamic diameter (about 30 nm), CHL promoted the stabilization of vesicles. Hydrogen bonding interactions were verified by the shift in -OH stretching over 3300-3500 cm-1. This manifested in an increased phase transition temperature (Tm) of SL liposomes. Tm increased further upon incorporation of cryoprotectants, particularly with β-CD. Enthalpic changes were indicative of an affinity interaction between phospholipids and cryoprotectants, regardless of the presence of CHL. β-CD showed concentration-dependent changes in the energetics of this interaction. The affinity of cryoprotectant-liposome interaction has been ranked as β-CD ≫ THL > MNT.

Concentration-dependence of specific rotation of optically active glycerol analogues and structurally related compounds: The significance of intermolecular hydrogen bonding

Specific rotation of optically active glycerol analogues, (S)-3-(benzyloxy)propane-1,2-diol [(S)-1], (S)-3-methoxypropane-1,2-diol [(S)-6] and (S)-3-phenoxypropane-1,2-diol [(S)-13], changed its sign from (+) to (–) with increasing concentration in CHCl3, whereas no significant concentration-dependent change was observed in MeOH. The 1H NMR spectrum of (S)-1 showed concentration-dependent changes of the chemical shift in CDCl3. Intermolecular interaction by OH⋯OH hydrogen bonds was suggested by single crystal X-ray crystallography of (S)-13. The concentration-dependent changes of specific rotation of (S)-1, (S)-6, and (S)-13 in CHCl3 can therefore be presumed to be due to self-assembly of these compounds via intermolecular hydrogen bonding at high concentration. The remarkable concentration-dependent changes in specific rotation were also observed to occur in the compounds with related chemical structures, such as (S)-3-hydroxy-4-methoxy-4-oxobutanoic acid [(S)-10], (S)-1-[(2-methylpropan-2-yl)oxycarbonyl]pyrrolidine-2-carboxylic acid [Boc-L-Pro-OH, (S)-14], (R)-3-hydroxy-4,4-dimethylhydrofran-2(3H)-one [(R)-15], (R)-tetrahydrofuran-2-carboxylic acid [(R)-16], (S)-3-methyl-2-[(2-methylpropan-2-yl)oxycarbonylamino]butanoic acid [Boc-L-Val-OH, (S)-17], (R)-oxiran-2-ylmethanol [(R)-18], and (4S)-4-isopropyloxazolidin-2-one [(S)-19]. The existence of intermolecular interaction by C=O⋯HO hydrogen bonds was suggested by single crystal X-ray crystallography of (S)-10, (S)-13, and (S)-14. Thus, this series of chiral compounds have multiple functional groups in appropriate positions that serve as hydrogen-bond donors and/or acceptors, resulting in significant concentration-dependent changes of specific rotation.

Spin-crossover cobalt(II) complexes exhibiting temperature- and concentration-dependent optical changes in solution.

This work investigated the spin states of the cobalt(II) complexes [Co(L1)2](X)2 (1·X; L1 = 4'-(4-N,N'-diphenylaminophenyl)-2,2':6',2''-terpyridine, X = PF6, BPh4) and [Co(L2)2](X)2 (2·X; L2 = 4'-(4-N,N'-dimethylaminophenyl)-2,2':6',2''-terpyridine, X = PF6, BPh4) in the solid state and in solution. In the solid state, 1·PF6 and 2·PF6, both containing smaller PF6- counter anions, showed gradual spin-crossover. In contrast, 1·BPh4 and 2·BPh4 remained in the high-spin state over the temperature range of 5-400 K due to a lower degree of molecular cooperativity. Each of the cobalt(II) complexes exhibited effects of temperature and concentration on their absorption spectra that were related to the spin states in various organic solvents. This work provides new insights into the spectroscopic properties resulting from the spin states of cobalt(II) complexes in solution.

Ratio-fluorescent and naked-eye visualized dual-channel sensing strategy for Cu2+ and alkaline phosphatase activity assay.

The levels of Cu2+ and alkaline phosphatase (ALP) are the important indicators of the developed stage of the relative diseases. Herein, a binary ratio-fluorescent and smartphone-assisted visual strategy basing on 4'-aminomethyl-4, 5', 8-trimethylpsoralen (AMT) and the oxidation of o-phenylenediamine was developed. Under the action of Cu2+, the fluorescent molecule, 3-diaminophenazine (DAP) formed which can act as a fluorescent acceptor of the ratio-fluorescent sensor. The emission spectrum of AMT overlapped with the excitation spectrum of DAP and, thus, it can act as the fluorescent donor of the ratio-fluorescent sensor. With the increasing concentration of Cu2+ and ALP, the fluorescent intensity of AMT decreased and the fluorescent intensity of DAP increased. The dual-emission reverse change ratio-fluorescent sensor realized the sensitive detection Cu2+ and ALP with the detection limits of 2nM and 0.03 U/mL, respectively. In addition, the acceptable recoveries were obtained when the Cu2+ and ALP in spiked samples were detected. Furthermore, the relative activity of ALP was assessed by increasing the concentrations of the inhibitor Na3VO4 and IC50 of 25μM was obtained. Importantly, the target concentration-dependent color change of DAP allowed us to utilize R/B ratio values to design the smartphone-assisting visual detection model of Cu2+ and ALP activity with the detection limits of 0.1μM and 0.18 U/mL. This simple, flexible, dual-mode sensor strategy has a potential for disease diagnosis and drug screening.

Coagulation Factor Xa Has No Effects on the Expression of PAR1, PAR2, and PAR4 and No Proinflammatory Effects on HL-1 Cells.

Atrial fibrillation (AF), characterised by irregular high-frequency contractions of the atria of the heart, is of increasing clinical importance. The reasons are the increasing prevalence and thromboembolic complications caused by AF. So-called atrial remodelling is characterised, among other things, by atrial dilatation and fibrotic remodelling. As a result, AF is self-sustaining and forms a procoagulant state. But hypercoagulation not only appears to be the consequence of AF. Coagulation factors can exert influence on cells via protease-activated receptors (PAR) and thereby the procoagulation state could contribute to the development and maintenance of AF. In this work, the influence of FXa on Heart Like-1 (HL-1) cells, which are murine adult atrial cardiomyocytes (immortalized), was investigated. PAR1, PAR2, and PAR4 expression was detected. After incubations with FXa (5-50 nM; 4-24 h) or PAR1- and PAR2-agonists (20 µM; 4-24 h), no changes occurred in PAR expression or in the inflammatory signalling cascade. There were no time- or concentration-dependent changes in the phosphorylation of the MAP kinases ERK1/2 or the p65 subunit of NF-κB. In addition, there was no change in the mRNA expression of the cell adhesion molecules (ICAM-1, VCAM-1, fibronectin). Thus, FXa has no direct PAR-dependent effects on HL-1 cells. Future studies should investigate the influence of FXa on human cardiomyocytes or on other cardiac cell types like fibroblasts.

Environmental chemicals change extracellular lipidome of mature human white adipocytes

Certain environmental chemicals affect the body's energy balance and are known as metabolism disrupting chemicals (MDCs). MDCs have been implicated in the development of metabolic diseases, such as obesity and type 2 diabetes. In contrast to their well-known impact on developing adipocytes, MDC effects leading to altered energy balance and development of insulin resistance in mature white adipocytes, constituents of adult adipose tissue, are largely unclear.Here, we investigated the effects of six well-established environmental MDCs (bisphenol A (BPA), perfluorooctanoic acid (PFOA), triclosan (TCS), p,p-dichlorodiphenyl-dichloroethylene (ppDDE), tributyltin chloride (TBT) and triphenyl phosphate (TPP)) on mature human white adipocytes derived from mesenchymal stem cells in vitro. We aimed to identify biomarkers and sensitive endpoints of their metabolism disrupting effects. While most of the tested exposures had no effect on adipocyte glucose consumption, lipid storage and assessed gene expression endpoints, the highest concentration of triclosan affected the total lipid storage and adipocyte size, as well as glucose consumption and mRNA expression of the glucose transporter GLUT1, leptin and adiponectin. Additionally, an increased expression of adiponectin was observed with TPP and the positive control PPARγ agonist rosiglitazone.In contrast, the lipidomic analysis of the cell culture medium after a 3-day exposure was extremely sensitive and revealed concentration-dependent changes in the extracellular lipidome of adipocytes exposed to nearly all studied chemicals. While some of the extracellular lipidome changes were specific for the MDC used, some effects were found common to several tested chemicals and included increases in lysophosphatidylcholines, glycerophospholipids and ceramides and a decrease in fatty acids, with possible implications in inflammation, lipid and glucose uptake.This study points to early signs of metabolic disruption and likely systemic effects of mature adipocyte exposure to environmental chemicals, as well as to the need to include lipidomic endpoints in the assessment of adverse effects of MDCs.

Mechanosensitivity and mechanotransductive properties of osteoclasts.

Mechanical loading is essential for maintaining bone health. Here, we aimed to investigate the role of ATP and ADP in the mechanotransduction of bone-resorptive osteoclasts. Single osteoclast in primary cultures from 10 to 12-wk-old mice was mechanically stimulated by a gentle touch with a micropipette. Changes in cytosolic free calcium [Ca2+]i were analyzed in Fura-2 loaded osteoclasts. The cell injury was assessed by analyzing the cellular Fura-2 loss and classified as severe or mild using k-means. Osteoclasts responded to mechanical stimuli with transient calcium elevation (primary responders) and transduced these signals to neighboring cells, which responded with delayed calcium elevations (secondary responders). Severely injured osteoclasts had higher calcium transients than mildly injured cells. Fluid shear stress similarly induced reversible cell injury in osteoclasts. Secondary responses were abolished by treatment with A-804598, a specific inhibitor of P2X7, but not suramin, a broad P2 receptor blocker. Osteoclasts responded to ATP and ADP with concentration-dependent changes in [Ca2+]i. We performed osteoclast micropipette stimulation in the presence of phosphoenolpyruvate and pyruvate kinase which converted all ADP in solution to ATP, or with hexokinase converting all ATP to ADP. Osteoclasts with mild membrane injury demonstrated similar calcium responses in ATP and ADP-rich environments. However, when the mechanotransductive signal to severe osteoclast injury was converted to ADP, the fraction of secondary responders and their [Ca2+]i amplitude was higher. This study suggests the importance of osteoclast mechanobiology and the role of ADP-mediated signaling in conditions of altered mechanical loading associated with bone loss.NEW & NOTEWORTHY Osteoclasts are rarely considered as cells that participate in mechanical signaling in bone. We show that osteoclasts are capable of sensing and transmitting mechanical signals to neighboring cells. Mechanical stimulation commonly induces minor repairable membrane injury in osteoclasts. ATP and especially ADP were found to play important roles in the mechanoresponsiveness of osteoclasts. This study highlights the importance of osteoclast mechanobiology especially in conditions of altered mechanical loading associated with bone loss, such as in microgravity.

Bei Mu Gua Lou San facilitates mucus expectoration by increasing surface area and hydration levels of airway mucus in an air-liquid-interface cell culture model of the respiratory epithelium

BackgroundBei Mu Gua Lou San (BMGLS) is an ancient formulation known for its moisturizing and expectorant properties, but the underlying mechanisms remain unknown. We investigated concentration-dependent effects of BMGLS on its rehydrating and mucus-modulating properties using an air-liquid-interface (ALI) cell culture model of the Calu-3 human bronchial epithelial cell line and primary normal human bronchial epithelial cells (NHBE), and specifically focused on quantity and composition of the two major mucosal proteins MUC5AC and MUC5B.MethodsALI cultures were treated with BMGLS at different concentrations over three weeks and evaluated by means of histology, immunostaining and electron microscopy. MUC5AC and MUC5B mRNA levels were assessed and quantified on protein level using an automated image-based approach. Additionally, expression levels of the major mucus-stimulating enzyme 15-lipoxygenase (ALOX15) were evaluated.ResultsBMGLS induced concentration-dependent morphological changes in NHBE but not Calu-3 ALI cultures that resulted in increased surface area via the formation of herein termed intra-epithelial structures (IES). While cellular rates of proliferation, apoptosis or degeneration remained unaffected, BMGLS caused swelling of mucosal granules, increased the area of secreted mucus, decreased muco-glycoprotein density, and dispensed MUC5AC. Additionally, BMGLS reduced expression levels of MUC5AC, MUC5B and the mucus-stimulating enzyme 15-lipoxygenase (ALOX15).ConclusionsOur studies suggest that BMGLS rehydrates airway mucus while stimulating mucus secretion by increasing surface areas and regulating goblet cell differentiation through modulating major mucus-stimulating pathways.

Vascular endothelial dysfunction induced by 3 bromofluoranthene via MAPK mediated NF B proinflammatory pathway and intracellular ROS generation

Abstract 3-Bromofluoranthene (3-BrFlu) is the secondary metabolite of fluoranthene, which is classified as a polycyclic aromatic hydrocarbon, through bromination and exists in the fine particulate matter of air pollutants. Endothelial dysfunction plays a critical role in the pathogenesis of cardiovascular and vascular diseases. Little is known about the molecular mechanism of 3-BrFlu on endothelial dysfunction in vivo and in vitro assay. In the present study, 3-BrFlu included concentration-dependent changes in ectopic angiogenesis of the sub-intestinal vein and dilation of the dorsal aorta in zebrafish. Disruption of vascular endothelial integrity and up-regulation of vascular endothelial permeability were also induced by 3-BrFlu in a concentration-dependent manner through pro-inflammatory responses in vascular endothelial cells, namely SVEC4-10 cells. Generation of pro-inflammatory mediator PGE2 was induced by 3-BrFlu through COX2 expression. Expression of COX2 and generation of pro-inflammatory cytokines, including TNFa and IL-6, were induced by 3-BrFlu through phosphorylation of NF-kB p65, which was mediated by phosphorylation of MAPK including p38 MAPK, ERK and JNK. Furthermore, generation of intracellular ROS was induced by 3-BrFlu, which is associated with the down-regulated activities of the antioxidant enzyme (AOE), including SOD and catalase. We also found that 3-BrFlu up-regulated expression of the AOE and HO-1 induced by 3-BrFlu through Nrf-2 expression. However, the 3-BrFlu-induced upregulation of AOE and HO-1 expression could not be revised the responses of vascular endothelial dysfunction. In conclusion, 3-BrFlu is a hazardous substance that results in vascular endothelial dysfunction through the MAPK-mediated-NFkB pro-inflammatory pathway and intracellular ROS generation.

Bile Is a Selective Elevator for Mucosal Mechanics and Transport.

Mucus mechanically protects the intestinal epithelium and impacts the absorption of drugs, with a largely unknown role for bile. We explored the impacts of bile on mucosal biomechanics and drug transport within mucus. Bile diffused with square-root-of-time kinetics and interplayed with mucus, leading to transient stiffening captured in Brillouin images and a concentration-dependent change from subdiffusive to Brownian-like diffusion kinetics within the mucus demonstrated by differential dynamic microscopy. Bile-interacting drugs, Fluphenazine and Perphenazine, diffused faster through mucus in the presence of bile, while Metoprolol, a drug with no bile interaction, displayed consistent diffusion. Our findings were corroborated by rat studies, where co-dosing of a bile acid sequestrant substantially reduced the bioavailability of Perphenazine but not Metoprolol. We clustered over 50 drugs based on their interactions with bile and mucin. Drugs that interacted with bile also interacted with mucin but not vice versa. This study detailed the dynamics of mucus biomechanics under bile exposure and linked the ability of a drug to interact with bile to its abbility to interact with mucus.

3D printing MOF nanozyme hydrogel with dual enzymatic activities and visualized glucose monitoring for diabetic wound healing

Promoting rapid healing of diabetic wounds caused by hyperglycemia, bacterial infection, and chronic inflammation is a global challenge. To address this issue, we design and prepare a novel cerium-based MOF nanozyme hydrogel via 3D printing technology to provide a personalized hydrogel wound dressing. The hydrogel is unique in that cerium-based MOFs are grown into the hydrogel network, simplifying the printing process of MOF hydrogel. The prepared hydrogel exhibits specific catalytic activity to various oxygen free radicals and glucose concentration-dependent color changes due to the interconversion between different valence cerium ions. This feature allows for indirect monitoring of glucose content around the wound. Additionally, the hydrogel presented high antibacterial properties and biocompatibility. In animal experiments, diabetic wounds in rats with a size of 1 cm2 fully healed within 21 days due to the synergistic effect of the anti-inflammatory and hyperglycemia capabilities of the cerium-based MOF nanozyme hydrogel. The results suggest that this novel hydrogel will revolutionize traditional treatment methods in diabetic wounds and provide an efficient, rapid, personalized treatment program.

Cytotoxicity and Genotoxicity Evaluation of Zanthoxylum rhoifolium Lam and In Silico Studies of Its Alkaloids.

The alkaloids isolated from Zanthoxylum rhoifolium have demonstrated great pharmacological potential; however, the toxic profiles of these extracts and fractions are still not well elucidated. This study evaluated the toxicity of the ethanol extract (EEZR) and neutral (FNZR) and alkaloid (FAZR) fractions. Chemical characterization was performed by chromatographic methods: thin-layer chromatography (TLC) and high-performance liquid chromatography coupled with diode array detection (HPLC-DAD). The cytotoxicity of the samples was evaluated in human hepatocellular carcinoma (HepG2) cells using the cell viability method (MTT) and mutagenicity by the Allium cepa assay (ACA). Alkaloids isolated from the species were selected for toxicity prediction using preADMET and PROTOX. The molecular docking of the topoisomerase II protein (TOPOII) was used to investigate the mechanism of cell damage. In the EEZR, FNZR, and FAZR, the presence of alkaloids was detected in TCL and HPLC-DAD analyses. These samples showed a 50% inhibitory concentration (IC50) greater than 400 μg/mL in HepG2 cells. In ACA, time- and concentration-dependent changes were observed, with a significant reduction in the mitotic index and an increase in chromosomal aberrations for all samples. Nuclear sprouts and a micronucleus of the positive control (PC) were observed at 10 µg/mL and in the FAZR at 30 µg/mL; a chromosomal bridge in FNZR was observed at 105 µg/mL, CP at a concentration of 40 µg/mL, and nuclear bud and mitotic abnormalities in the EEZR were observed at 170 µg/mL. The alkaloids with a benzophenanthridine were selected for the in silico study, as structural alterations demonstrated certain toxic effects. Molecular docking with topo II demonstrated that all alkaloids bind to the protein. In summary, the fractionation of Z. rhoifolium did not interfere with toxicity; it seems that alkaloids with a benzophenanthridine nucleus may be involved in this toxicity.

Proteomic analyses of primary human villous trophoblasts exposed to flame retardant BDE-47 using SWATH-MS

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants and recognized developmental toxicants that are detectable in placental tissues. Higher levels of in utero PBDE exposure have been associated with an increased risk of adverse birth outcomes. During pregnancy, cytotrophoblasts (CTBs) from the placenta play critical roles in the formation of the maternal-fetal interface via uterine invasion and vascular remodeling. The differentiation of these cells towards an invasive phenotype is crucial for proper placental development. We previously have shown that BDE-47 can impact CTB viability and hinder the ability of these cells to migrate and invade. To expand on potential toxicological mechanisms, we utilized quantitative proteomic approaches to identify changes in the global proteome of mid-gestation primary human CTBs after exposure to BDE-47. Using sequential window acquisition of all theoretical fragment-ion spectra (SWATH), we identified 3024 proteins in our CTB model of differentiation/invasion. Over 200 proteins were impacted as a function of BDE-47 exposure (1 μM and 5 μM) across the treatment period (15, 24, and 39 h). The differentially expressed molecules displayed time- and concentration-dependent changes in expression and were enriched in pathways associated with aggregatory and adhesive processes. Network analysis identified CYFIP1, a molecule previously unexplored in a placental context, to be dysregulated at BDE-47 concentrations previously seen to impact CTB migration/invasion. Our SWATH-MS dataset thus demonstrates BDE-47 impacts the global proteome of differentiating CTBs and serves as a valuable resource for further understanding of the relationship between environmental chemical exposures and placental development and function. Availability of data and materialRaw chromatograms are deposited on the MassIVE proteomic database (https://massive.ucsd.edu) under accession number MSV000087870. Normalized relative abundances are also available as Table S1.

Dispersion of low concentration of particulate or fibrillated protein fillers into plant protein melts and their impact on the elasticity and tenderness gap of plant-based foods

The development of plant-based foods has emerged as a promising strategy to decrease meat consumption. Using predominantly globular plant proteins challenges the crafting of cohesive, viscoelastic, and anisotropic structures similar to animal meat. In this study, we investigated the effect of incorporating low concentrations (<1%, w/w) of the polar gelatin or the non-polar zein on the mechanical properties of high moisture meat analogue prototypes. These proteins were studied in both particulate (bulk) and nano-fibrillated forms. Building on our previous work, soy protein (68% protein) and mung bean protein (81% protein) concentrates were chosen based on their distinct protein purity and high propensity to rearrange into new ordered secondary structural elements upon extrusion. Gelatin and zein were incorporated into the extrusion process via aqueous dispersion in particulate form or previously converted into nanofibers (210–440 nm diameter) using food-grade electrospinning. The incorporation of both fillers (either particulate or fibrillate) decreased the elasticity and Warner-Bratzler Shear Force (WBSF, known to be inversely correlated to meat tenderness) of mung bean extrudates. However, the addition of 0.1% fibrillated gelatin or particulate/fibrillated zein increased up to 44% or 22% the WBSF of soy extrudates, respectively. In all cases, the incorporation of fillers caused dramatic concentration-dependent changes in the secondary structures (FTIR) of soy proteins and the water mobility (LF-NMR) of extrudates. This work highlights the potential of multifunctional fillers and the combination of top-down (extrusion) and bottom-up (fibrillation) approaches to reduce the tenderness gap between animal meat and structured foods made with less-refined plant-protein fractions.

Stealthy Player in Lipid Experiments? EDTA Binding to Phosphatidylcholine Membranes Probed by Simulations and Monolayer Experiments.

Ethylenediaminetetraacetic acid (EDTA) is frequently used in lipid experiments to remove redundant ions, such as Ca2+, from the sample solution. In this work, combining molecular dynamics (MD) simulations and Langmuir monolayer experiments, we show that on top of the expected Ca2+ depletion, EDTA anions themselves bind to phosphatidylcholine (PC) monolayers. This binding, originating from EDTA interaction with choline groups of PC lipids, leads to the adsorption of EDTA anions at the monolayer surface and concentration-dependent changes in surface pressure as measured by monolayer experiments and explained by MD simulations. This surprising observation emphasizes that lipid experiments carried out using EDTA-containing solutions, especially of high concentrations, must be interpreted very carefully due to potential interfering interactions of EDTA with lipids and other biomolecules involved in the experiment, e.g., cationic peptides, that may alter membrane-binding affinities of studied compounds.

Phase segregation and miscibility of TiOx nanocomposites in Gd-doped ceria solid electrolyte material.

Electro-chemo-mechanical (ECM) coupling refers to mechanical deformation due to electrochemically driven compositional change in a solid. An ECM actuator producing micrometre-size displacements and long-term stability at room temperature was recently reported, comprising a 20 mol% Gd-doped ceria (20GDC), a solid electrolyte membrane, placed between two working bodies made of TiOx/20GDC (Ti-GDC) nanocomposites with Ti concentration of 38 mol%. The volumetric changes originating from oxidation or reduction in the local TiOx units are hypothesized to be the origin of mechanical deformation in the ECM actuator. Studying the Ti concentration-dependent structural changes in the Ti-GDC nanocomposites is therefore required for (i) understanding the mechanism of dimensional changes in the ECM actuator and (ii) maximizing the ECM response. Here, the systematic investigation of the local structure of the Ti and Ce ions in Ti-GDC over a broad range of Ti concentrations using synchrotron X-ray absorption spectroscopy and X-ray diffraction is reported. The main finding is that, depending on the Ti concentration, Ti atoms either form a cerium titanate or segregate into a TiO2 anatase-like phase. The transition region between these two regimes with Ti(IV) concentration between 19% and 57% contained strongly disordered TiOx units dispersed in 20GDC containing Ce(III) and Ce(IV) and hence rich with oxygen vacancies. As a result, this transition region is proposed to be the most advantageous for developing ECM-active materials.

Upconversion nanoparticles anchored MnO2 nanosheets for luminescence “turn on” detecting hydrogen peroxide

The sensitively and reliably detecting hydrogen peroxide (H2O2) is of significant for biology and environment protection fields. Herein, we reported a high sensitive H2O2 nanoprobe based on upconversion nanoparticles (UCNPs) anchored MnO2 nanosheets. In which, DNA modified NaYF4@NaYF4:Yb,Tm core–shell nanoparticles were anchored onto the MnO2 nanosheets surface via π-π stacking. Owing to the luminescence resonance energy transfer, the blue luminescence of UCNPs was effectively quenched by MnO2 nanosheets, then the luminescence could be restored by adding H2O2 for reducing MnO2 to Mn2+, and achieving a H2O2 concentration-dependent luminescence change, the detection limit could reach to 0.23 nM (S/N = 3). The proposed method could detect H2O2 in serum, lake water and real samples. Thus, a desired upconversion luminescence sensing strategy for detection H2O2 in life and environmental analysis was successfully constructed. It may be provide a potential tool in disease diagnosis and environmental monitoring fields.

Not so dangerous? PET microplastics toxicity on freshwater microalgae and cyanobacteria

Microalgae and cyanobacteria are among the most important primary producers and are responsible for the production of 50–80% of the oxygen on Earth. They can be significantly affected by plastic pollution, as the vast majority of plastic waste ends up in rivers and then the oceans. This research focuses on green microalgae Chlorella vulgaris (C. vulgaris), Chlamydomonas reinhardtii (C. reinhardtii), filamentous cyanobacterium Limnospira (Arthrospira) maxima (L.(A.) maxima) and how they are affected by environmentally relevant PET-MPs (polyethylene-terephtalate microplastics). Manufactured PET-MPs have asymmetric shape, size between 3 and 7 μm and were used in concentrations ranging from 5 mg/L to 80 mg/L. The highest inhibitory rate of growth was found in C. reinhardtii (−24%). Concentration-dependent changes in chlorophyll a composition were found in C. vulgaris and C. reinhardtii, not in L. (A.) maxima. Furthermore, cell damage was detected in all three organisms by CRYO-SEM (shriveling, cell wall disruption), but the cyanobacterium was the least damaged. A PET-fingerprint was detected on the surface of all tested organisms using FTIR, indicating the adherence of PET-MPs. The highest rate of PET-MPs adsorption was detected in L. (A.) maxima. Specifically, characteristic spectra were observed at ∼721, 850, 1100, 1275, 1342, and 1715 cm−1 which are specific for functional groups of PET-MPs. Nitrogen and carbon content significantly increased in L. (A.) maxima under exposure to 80 mg/L due to the PET-MPs adherence and mechanical stress. In all three tested organisms, weak exposure-related ROS generation was detected. In general, cyanobacteria seem to be more resistant to the effects of MPs. However, organisms in the aquatic environment are exposed to MPs over a longer time scale, so it is important to use the present findings for further longer-term experiments on environmentally relevant organisms.

Diverse targets of SMN2-directed splicing-modulating small molecule therapeutics for spinal muscular atrophy.

Designing an RNA-interacting molecule that displays high therapeutic efficacy while retaining specificity within a broad concentration range remains a challenging task. Risdiplam is an FDA-approved small molecule for the treatment of spinal muscular atrophy (SMA), the leading genetic cause of infant mortality. Branaplam is another small molecule which has undergone clinical trials. The therapeutic merit of both compounds is based on their ability to restore body-wide inclusion of Survival Motor Neuron 2 (SMN2) exon 7 upon oral administration. Here we compare the transcriptome-wide off-target effects of these compounds in SMA patient cells. We captured concentration-dependent compound-specific changes, including aberrant expression of genes associated with DNA replication, cell cycle, RNA metabolism, cell signaling and metabolic pathways. Both compounds triggered massive perturbations of splicing events, inducing off-target exon inclusion, exon skipping, intron retention, intron removal and alternative splice site usage. Our results of minigenes expressed in HeLa cells provide mechanistic insights into how these molecules targeted towards a single gene produce different off-target effects. We show the advantages of combined treatments with low doses of risdiplam and branaplam. Our findings are instructive for devising better dosing regimens as well as for developing the next generation of small molecule therapeutics aimed at splicing modulation.