Deformation Of Cell Membrane Research Articles

Negatively curved cellular membranes promote BAIAP2 signaling hub assembly.

Plasma membrane deformations are associated with curvature-dependent protein enrichment that contributes to a wide array of cellular functions. While the spatio-temporal protein dynamics at membrane indentations is well characterized, relatively little is known about protein kinetics at outwardly deforming membrane sites. This is in part due to the lack of high throughput approaches to systematically probe the curvature-dependence of protein-membrane interactions. Here, we developed a nanopatterned array for multiplexed analysis of protein dynamics at negatively curved cellular membranes. Taking advantage of this robust and versatile platform, we explored how membrane shape influences the prototypic negative curvature sensing protein BAIAP2 and its effector proteins. We find assembly of multi-protein signaling hubs and increased actin polymerization at outwardly deformed membrane sections, indicative of curvature-dependent BAIAP2 activation. Collectively, this study presents technical and conceptual advancements towards a quantitative understanding of spatio-temporal protein dynamics at negatively curved membranes.

Piezo1-pannexin-1-P2X3 axis in odontoblasts and neurons mediates sensory transduction in dentinal sensitivity.

According to the "hydrodynamic theory," dentinal pain or sensitivity is caused by dentinal fluid movement following the application of various stimuli to the dentin surface. Recent convergent evidence in Vitro has shown that plasma membrane deformation, mimicking dentinal fluid movement, activates mechanosensitive transient receptor potential (TRP)/Piezo channels in odontoblasts, with the Ca2+ signal eliciting the release of ATP from pannexin-1 (PANX-1). The released ATP activates the P2X3 receptor, which generates and propagates action potentials in the intradental Aδ afferent neurons. Thus, odontoblasts act as sensory receptor cells, and odontoblast-neuron signal communication established by the TRP/Piezo channel-PANX-1-P2X3 receptor complex may describe the mechanism of the sensory transduction sequence for dentinal sensitivity. To determine whether odontoblast-neuron communication and odontoblasts acting as sensory receptors are essential for generating dentinal pain, we evaluated nociceptive scores by analyzing behaviors evoked by dentinal sensitivity in conscious Wistar rats and Cre-mediated transgenic mouse models. In the dentin-exposed group, treatment with a bonding agent on the dentin surface, as well as systemic administration of A-317491 (P2X3 receptor antagonist), mefloquine and 10PANX (non-selective and selective PANX-1 antagonists), GsMTx-4 (selective Piezo1 channel antagonist), and HC-030031 (selective TRPA1 channel antagonist), but not HC-070 (selective TRPC5 channel antagonist), significantly reduced nociceptive scores following cold water (0.1ml) stimulation of the exposed dentin surface of the incisors compared to the scores of rats without local or systemic treatment. When we applied cold water stimulation to the exposed dentin surface of the lower first molar, nociceptive scores in the rats with systemic administration of A-317491, 10PANX, and GsMTx-4 were significantly reduced compared to those in the rats without systemic treatment. Dentin-exposed mice, with somatic odontoblast-specific depletion, also showed significant reduction in the nociceptive scores compared to those of Cre-mediated transgenic mice, which did not show any type of cell deletion, including odontoblasts. In the odontoblast-eliminated mice, P2X3 receptor-positive A-neurons were morphologically intact. These results indicate that neurotransmission between odontoblasts and neurons mediated by the Piezo1/TRPA1-pannexin-1-P2X3 receptor axis is necessary for the development of dentinal pain. In addition, odontoblasts are necessary for sensory transduction to generate dentinal sensitivity as mechanosensory receptor cells.

Cetirizine more potently exerts mast cell-stabilizing property than diphenhydramine.

Cetirizine, a second-generation antihistamine, and diphenhydramine, a first-generation antihistamine, are among the most widely used anti-allergic drugs. In addition to longer duration of action and less incidence of sedative side effects, recent clinical studies also indicate a higher potency of cetirizine than diphenhydramine in the treatment or prevention of allergic disorders. In the present study, using the differential-interference contrast (DIC) microscopy, we examined the effects of cetirizine and diphenhydramine (1 μM to 1 mM) on the degranulation from rat peritoneal mast cells. Using fluorescence imaging of a water-soluble dye, lucifer yellow, we also examined their effects on the deformation of the plasma membrane. At relatively higher concentrations (100 μM, 1 mM), both cetirizine and diphenhydramine significantly reduced the numbers of degranulating mast cells. Of note, at 1 mM, cetirizine more markedly reduced the number than diphenhydramine, almost entirely suppressing the degranulation of mast cells. Additionally, 1 mM cetirizine and levocetirizine, another second-generation antihistamine, almost totally inhibited the process of exocytosis in mast cells and washed out the trapping of the lucifer yellow on the cell surface, while diphenhydramine and chlorpheniramine, another first-generation antihistamine, did not. This study provided in vitro evidence for the first time that cetirizine more potently inhibited the process of exocytosis in mast cells than diphenhydramine, indicating its higher potency as a mast cell-stabilizer. Such mast cell-stabilizing property of cetirizine could be ascribed to its counteracting effect on the plasma membrane deformation in degranulating mast cells.

Pharmacological Profile of Nigella sativa Seeds in Combating COVID-19 through In-Vitro and Molecular Docking Studies

COVID-19 infection is associated with elevated oxidative stress, systemic hyper-inflammatory responses, endothelial dysfunction, and red blood cell membrane deformability. Nigella sativa extract is widely used in alternative and complementary medicine systems in a large population, due to its highly therapeutic, economic, natural, and safe nature. The aim of this study was to evaluate the effect of N. sativa extract on oxidative stress, hemolysis, proteolysis, and glycation through in vitro studies, as well as to find out its anti-viral potential against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) using in silico studies. N. sativa seed extract (at 600 µg/mL) displayed 67.33% scavenging activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test, and 70.28% hydrogen peroxide reducing activity. N. sativa exhibited anti-proteolytic activity by decreasing heat-induced denaturation of bovine serum albumin (BSA) and egg albumin by 63.14% and 57.95%, respectively, and exhibited anti-proteinase potential of 66.28% at 600 μg/mL. In addition, heat-induced hemolysis and hypersalinity-induced hemolysis were inhibited by 57.86% and 61.7%, respectively, by the N. sativa seeds. N. sativa also inhibited browning intensity by 56.38%, and percent aggregation index by 51.38%, amyloid structure by 48.28%, and AGE-specific fluorescence by 52.18%, thereby protecting the native structure of BSA from glycation. The binding interactions between bioactive molecules of N. sativa seed with SARS-CoV-2 spike glycoprotein were proven by using in silico molecular docking tools. The functional amino acids involved in the interactions are Asp467, Thr108, Thr114, Ile468, Asn234, Gln155, Glu465, Arg466, Gly232, and Ile233, indicating the inhibiting property of N. sativa on SARS-CoV-2. Finally, we may infer that phytoconstituents of N. sativa seeds have the potential to protect against the spike protein of SARS-CoV-2. Studies on N. sativa seeds might act as a path to develop a potent alternative therapy against viral infections, especially COVID-19 infection, in the future. However, the limitations linked with the use of natural products are also needed to be considered in this regard.

Impact of Superoxide Dismutase Genetic Polymorphism (SOD2 Val16Ala) and Superoxide Dismutase Level on Disease Severity in a Cohort of Egyptian Sickle Cell Disease Patients.

BackgroundOxidative stress plays a pivotal role in the pathophysiology of sickle cell disease (SCD) and its associated disease complications. Superoxide Dismutases (SODs) are protective enzymes against oxidative stress. SOD2 deficiency results in the accumulation of oxidized red cell proteins, increased rate of hemoglobin oxidation, decreased red cell membrane deformability, and subsequently decreased red cells survival.ObjectiveThe current study was designed to determine the effect of SOD2 Val16Ala gene polymorphism (rs4880) on SOD2 level and their possible impact on SCD disease severity in a cohort of Egyptian SCD patients.MethodsGenotyping SOD2 Val16Ala polymorphism by TaqMan allelic discrimination assay for hundred SCD patients and a hundred age-sex matched healthy controls revealed the genotypic and allelic frequencies of the studied polymorphism in the SCD patients were close to that of the controls.ResultsSerum SOD2 level was significantly lower in those having the polymorphic genotypes (p=0.005). SOD2 level inversely correlates with the annual rate of hospitalization (r=−0.023, p= 0.038).ConclusionSOD2 Val16Ala polymorphism was associated with low serum SOD2 level that may predict disease severity.

The effect of blood viscosity on shear-induced hemolysis using a magnetically levitated shearing device.

Blood contacting medical devices, including rotary blood pumps, can cause shear-induced blood damage that may lead to adverse effects in patients. Due in part to an inadequate understanding of how cell-scale fluid mechanics impact red blood cell membrane deformation and damage, there is currently not a uniformly accepted engineering model for predicting blood damage caused by complex flow fields within ventricular assist devices (VADs). We empirically investigated hemolysis in a magnetically levitated axial Couette flow device typical of a rotary VAD. The device is able to accurately control the shear rate and exposure time experienced by blood and to minimize the effects of other uncharacterized stresses. Using this device, we explored the effects of both hematocrit and plasma viscosity on shear-induced hemolysis to characterize blood damage based on the viscosity-independent shear rate, rather than on shear stress. Over a shear rate range of 20 000 - 80 0001/s, the Index of Hemolysis (IH) was found to be dependent upon and well-predicted by the shear rate alone. IH was independent of hematocrit, bulk viscosity, or the suspension media viscosity and less correlated to shear stress (MSE=0.46-0.75) than to shear rate (MSE=0.06-0.09). This study recommends that future investigations of shear-induced blood damage report findings with respect to the viscosity-neutral term of shear rate, in addition to the bulk whole blood viscosity measured at an appropriate shear rate relevant to the flow conditions of the device.

Non-Cavitation Targeted Microbubble-Mediated Single-Cell Sonoporation.

Sonoporation employs ultrasound accompanied by microbubble (MB) cavitation to induce the reversible disruption of cell membranes and has been exploited as a promising intracellular macromolecular delivery strategy. Due to the damage to cells resulting from strong cavitation, it is difficult to balance efficient delivery and high survival rates. In this paper, a traveling surface acoustic wave (TSAW) device, consisting of a TSAW chip and a polydimethylsiloxane (PDMS) channel, was designed to explore single-cell sonoporation using targeted microbubbles (TMBs) in a non-cavitation regime. A TSAW was applied to precisely manipulate the movement of the TMBs attached to MDA-MB-231 cells, leading to sonoporation at a single-cell level. The impact of input voltage and the number of TMBs on cell sonoporation was investigated. In addition, the physical mechanisms of bubble cavitation or the acoustic radiation force (ARF) for cell sonoporation were analyzed. The TMBs excited by an ARF directly propelled cell membrane deformation, leading to reversible perforation in the cell membrane. When two TMBs adhered to the cell surface and the input voltage was 350 mVpp, the cell sonoporation efficiency went up to 83%.

Neurotherapeutic implications of sense and respond strategies generated by astrocytes and astrocytic tumours to combat pH mechanical stress.

AimsAstrocytes adapt to acute acid stress. Intriguingly, cancer cells with astrocytic differentiation thrive even better in an acidic microenvironment. How changes in extracellular pH (pHe) are sensed and measured by the cell surface assemblies that first intercept the acid stress, and how this information is relayed downstream for an appropriate survival response remains largely uncharacterized.Methods In vitro cell‐based studies were combined with an in vivo animal model to delineate the machinery involved in pH microenvironment sensing and generation of mechanoadaptive responses in normal and neoplastic astrocytes. The data was further validated on patient samples from acidosis driven ischaemia and astrocytic tumour tissues.ResultsWe demonstrate that low pHe is perceived and interpreted by cells as mechanical stress. GM3 acts as a lipid‐based pH sensor, and in low pHe, its highly protonated state generates plasma membrane deformation stress which activates the IRE1‐sXBP1‐SREBP2‐ACSS2 response axis for cholesterol biosynthesis and surface trafficking. Enhanced surface cholesterol provides mechanical tenacity and prevents acid‐mediated membrane hydrolysis, which would otherwise result in cell leakage and death.ConclusionsIn summary, activating these lipids or the associated downstream machinery in acidosis‐related neurodegeneration may prevent disease progression, while specifically suppressing this key mechanical ‘sense‐respond’ axis should effectively target astrocytic tumour growth.

Atomic force microscopy in the assessment of erythrocyte membrane mechanical properties with exposure to various physicochemical agents

Background: Mechanical properties of cell membranes and their structural organization are considered among the most important biological parameters affecting the functional state of the cell. Under the influence of various pathogenic factors, erythrocyte membranes lose their elasticity. The resulting changes in their biomechanical characteristics is an important, but poorly studied topic. It is of interest to study the deformation of native erythrocytes to a depth compatible with their deformation in the bloodstream.Aim: To investigate the patterns of deep deformation and the particulars of structural organization of native erythrocyte membranes before and after their exposure to physicochemical agents in vitro.Materials and methods: Cell morphology, nanostructure characteristics, and membrane deformation of native erythrocytes in a solution of hemoconservative CPD/SAGM were studied with atomic force microscope NTEGRA Prima. Hemin, zinc ions (Zn2+), and ultraviolet (UV) radiation were used as modifiers. To characterize the membrane stiffness, we measured the force curves F(h), hHz (the depth to which the probe immersion is described by interaction with a homogeneous medium), and the Young's modulus values of the erythrocyte membrane.Results: Exposure to hemin, Zn2+ and UV radiation led to transformation of the cell shape, appearance of topological defects and changes in mechanical characteristics of erythrocyte membranes. Under exposure to hemin, Young's modulus increased from 10±4 kPa to 27.2±8.6 kPa (p<0.001), exposure to Zn2+, to 21.4±8.7 kPa (p=0.002), and UV, to 18.8±5.6 kPa (p=0.001). The hHz value was 815±210 nm for the control image and decreased under exposure to hemin to 420±80 nm (p<0.001), Zn2+, to 370±90 nm (p<0.001), and UV, to 614±120 nm (p=0.001).Conclusion: The results obtained contribute to a deeper understanding of interaction between membrane surfaces of native erythrocytes and small vessel walls. They can be useful in clinical medicine as additional characteristics for assessment of the quality of packed red blood cells, as well as serve as a basis for biophysical studies into the mechanisms of action of oxidative processes of various origins.

Reprint of: Mechanosensitive ion channels in cell migration.

Cellular processes are initiated and regulated by different stimuli, including mechanical forces. Cell membrane mechanosensors represent the first step towards the conversion of mechanical stimuli to a biochemical or electrical response. Mechanosensitive (MS) ion channels form a growing family of ion gating channels that respond to direct physical force or plasma membrane deformations. A number of calcium (Ca2+) permeable MS channels are known to regulate the initiation, direction, and persistence of cell migration during development and tumour progression. While the evidence that links individual MS ion channels to cell migration is growing, a unified analysis of the molecular mechanisms regulated downstream of MS ion channel activation is lacking. In this review, we describe the MS ion channel families known to regulate cell migration. We discuss the molecular mechanisms that act downstream of MS ion channels with an emphasis on Ca2+ mediated processes. Finally, we propose the future directions and impact of MS ion channel activity in the field of cell migration.

Tunneling nanotubes and related structures: molecular mechanisms of formation and function.

Tunneling nanotubes (TNTs) are F-actin-based, membrane-enclosed tubular connections between animal cells that transport a variety of cellular cargo. Over the last 15 years since their discovery, TNTs have come to be recognized as key players in normal cell communication and organism development, and are also exploited for the spread of various microbial pathogens and major diseases like cancer and neurodegenerative disorders. TNTs have also been proposed as modalities for disseminating therapeutic drugs between cells. Despite the rapidly expanding and wide-ranging relevance of these structures in both health and disease, there is a glaring dearth of molecular mechanistic knowledge regarding the formation and function of these important but enigmatic structures. A series of fundamental steps are essential for the formation of functional nanotubes. The spatiotemporally controlled and directed modulation of cortical actin dynamics would be required to ensure outward F-actin polymerization. Local plasma membrane deformation to impart negative curvature and membrane addition at a rate commensurate with F-actin polymerization would enable outward TNT elongation. Extrinsic tactic cues, along with cognate intrinsic signaling, would be required to guide and stabilize the elongating TNT towards its intended target, followed by membrane fusion to create a functional TNT. Selected cargoes must be transported between connected cells through the action of molecular motors, before the TNT is retracted or destroyed. This review summarizes the current understanding of the molecular mechanisms regulating these steps, also highlighting areas that deserve future attention.

Antibacterial mechanism of Brevinin-2GHk, an antimicrobial peptide from Fejervarya limnocharis skin

To investigate the secondary structure, physicochemical properties and antibacterial activity of Brevinin- 2GHk (BR2GK), an antimicrobial peptide from frog skin, and explore its antibacterial mechanism. BR2GK was synthesized, purified with high performance liquid chromatography (HPLC) and identified using mass spectrometry. Circular dichroism was used to determine the secondary structure and physicochemical properties of BR2GK. Two-fold dilution method was used to determine the antibacterial activity of BR2GK, and its antibacterial mechanism was explored using laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM). The hemolytic activity of BR2GK was analyzed in red blood cells. Isothermal titration calorimetry (ITC) and surface plasmon resonance imaging (SPRi) were employed to detect the binding of BR2GK to lipopolysaccharide (LPS), and the antioxidant activity of BR2GK was evaluated using biochemical kits. The synthesized BR2GK, with a purity exceeding 95% after purification, had the basic characteristics of cationic antimicrobial peptides. BR2GK consisted mainly of α-helical structure in SDS solution and exhibited a broad-spectrum antibacterial activity. Antibacterial activity assay showed that BR2GK had inhibitory and killing activity against a variety of strains with a minimum inhibitory concentration (MIC) of 2.76 μmol/L against Staphylococcus aureus. Observation with LSCM and SEM showed that BR2GK at an active concentration caused bacterial cell membrane damage, cell swelling, contraction, deformation, and massive exudation of intracellular contents without causing hemolysis. ITC showed that the binding affinity KD of BR2GK to LPS was 18.2±0.8 μmol/L. The antioxidant test showed that BR2GK was capable of effectively scavenging NO, ABTS and DPPH. BR2GK, as a broad-spectrum antibacterial peptide with also a strong antioxidant capacity, does not cause hemolysis and is capable of binding to LPS. BR2GK has an important value for future design and synthesis of antimicrobial peptides with stronger antibacterial activity and lower cytotoxicity.

Deformation Measurements of Neuronal Excitability Using Incoherent Holography Lattice Light-Sheet Microscopy (IHLLS)

Stimuli to excitable cells and various cellular processes can cause cell surface deformations; for example, when excitable cell membrane potentials are altered during action potentials. However, these cellular changes may be at or below the diffraction limit (in dendrites the structures measured are as small as 1 µm), and imaging by traditional methods is challenging. Using dual lenses incoherent holography lattice light-sheet (IHLLS-2L) detection with holographic phase imaging of selective fluorescent markers, we can extract the full-field cellular morphology or structural changes of the object’s phase in response to external stimulus. This approach will open many new possibilities in imaging neuronal activity and, overall, in light sheet imaging. In this paper, we present IHLLS-2L as a well-suited technique for quantifying cell membrane deformation in neurons without the actuation of a sample stage or detection microscope objective.

Sol-Gel Synthesis of Dy-Substituted Ni0.4Cu0.2Zn0.4(Fe2-xDyx)O4 Nano Spinel Ferrites and Evaluation of Their Antibacterial, Antifungal, Antibiofilm and Anticancer Potentialities for Biomedical Application.

BackgroundThe constant rise of microbial biofilm formation and drug resistance to existing antimicrobial drugs poses a significant threat to community health around the world because it reduces the efficacy and efficiency of treatments, increasing morbidity, mortality, and health-care expenditures. As a result, there is an urgent need to develop novel antimicrobial agents that inhibit microbial biofilm formation.MethodsThe [Ni0.4Cu0.2Zn0.4](Fe2-xDyx)O4(x≤0.04) (Ni-Cu-Zn) nano spinel ferrites (NSFs) have been synthesized by the sol–gel auto-combustion process and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray (EDX) and transmission electron microscopy (TEM). The antimicrobial, antibiofilm and antiproliferative activities of Ni-Cu-Zn NSFs were also examined.ResultsThe XRD pattern confirms the secondary phase DyFeO3 and Fe2O3 for substituted Dy3+ samples, and the crystallite size ranged from 10 to 19 nm. TEM analysis of NSFs revealed that the particles were cube-shaped and 15nm in size. NSFs exhibited significant antimicrobial, antibiofilm and antiproliferative activity. At concentration of 1 mg/mL, it was found that the NSFs (ie, x=0.0, x=0.01, x=0.02, x=0.03 and x=0.04) inhibit biofilm formation by 27.6, 26.2, 58.5, 33.3 and 25% for methicillin-resistant Staphylococcus aureus (MRSA) and 47.5, 43.5, 48.6, 58.3 and 26.6% for Candida albicans, respectively. SEM images demonstrate that treating MRSA and C. albicans biofilms with NSFs significantly reduces cell adhesion, colonization and destruction of biofilm architecture and extracellular polymeric substances matrices. Additionally, SEM and TEM examination revealed that NSFs extensively damaged the cell walls and membranes of MRSA and C. albicans. Huge ultrastructural alteration such as deformation, disintegration and separation of cell wall and membrane from the cells was observed, indicating significant loss of membrane integrity, which eventually led to cell death. Furthermore, it was observed that NSF inhibited the cancer cell growth and proliferation of HCT-116 in a dose-dependent manner.ConclusionThe current study demonstrated that the synthesized Ni-Cu-Zn NSFs could be used to develop potential antimicrobial surface coatings agents for a varieties of biomedical-related materials and devices in order to prevent the biofilms formation and their colonization. Furthermore, the enhanced antiproliferative properties of manufactured SNFs suggest a wide range of biomedical applications.

Ventral stress fibers induce plasma membrane deformation in human fibroblasts.

Interactions between the actin cytoskeleton and the plasma membrane are important in many eukaryotic cellular processes. During these processes, actin structures deform the cell membrane outward by applying forces parallel to the fiber’s major axis (as in migration) or they deform the membrane inward by applying forces perpendicular to the fiber’s major axis (as in the contractile ring during cytokinesis). Here we describe a novel actin–membrane interaction in human dermal myofibroblasts. When labeled with a cytosolic fluorophore, the myofibroblasts displayed prominent fluorescent structures on the ventral side of the cell. These structures are present in the cell membrane and colocalize with ventral actin stress fibers, suggesting that the stress fibers bend the membrane to form a “cytosolic pocket” that the fluorophores diffuse into, creating the observed structures. The existence of this pocket was confirmed by transmission electron microscopy. While dissolving the stress fibers, inhibiting fiber protein binding, or inhibiting myosin II binding of actin removed the observed pockets, modulating cellular contractility did not remove them. Taken together, our results illustrate a novel actin–membrane bending topology where the membrane is deformed outward rather than being pinched inward, resembling the topological inverse of the contractile ring found in cytokinesis.

Counteraction of Biofilm Formation and Antimicrobial Potential of Terminalia catappa Functionalized Silver Nanoparticles against Candida albicans and Multidrug-Resistant Gram-Negative and Gram-Positive Bacteria.

Biofilms not only protect bacteria and Candida species from antibiotics, but they also promote the emergence of drug-resistant strains, making eradication more challenging. As a result, novel antimicrobial agents to counteract biofilm formation are desperately needed. In this study, Terminalia catappa leaf extract (TCE) was used to optimize the TCE-capped silver nanoparticles (TCE-AgNPs) via a one-pot single-step method. Varied concentrations of TCE have yielded different sized AgNPs. The physico-chemical characterization of TCE-AgNPs using UV-Vis, SEM, TEM, FTIR, and Raman spectroscopy have confirmed the formation of nanostructures, their shape and size and plausible role of TCE bio-active compounds, most likely involved in the synthesis as well as stabilization of NPs, respectively. TCE-AgNPs have been tested for antibiofilm and antimicrobial activity against multidrug-resistant Pseudomonas aeruginosa (MDR-PA), methicillin-resistant Staphylococcus aureus (MRSA), and Candida albicans using various microbiological protocols. TCE-Ag-NPs−3 significantly inhibits biofilm formation of MDR-PA, MRSA, and C. albicans by 73.7, 69.56, and 63.63%, respectively, at a concentration of 7.8 µg/mL, as determined by crystal violet microtiter assay. Furthermore, SEM micrograph shows that TCE-AgNPs significantly inhibit the colonization and adherence of biofilm forming cells; individual cells with loss of cell wall and membrane integrity were also observed, suggesting that the biofilm architecture and EPS matrix were severely damaged. Moreover, TEM and SEM images showed that TCE-AgNPs brutally damaged the cell wall and membranes of MDR-PA, MRSA, and C. albicans. Additionally, extreme ultrastructural changes such as deformation, disintegration, and separation of cell wall and membrane from the cells, have also been observed, indicating significant loss of membrane and cell wall integrity, which eventually led to cell death. Overall, the research revealed a simple, environmentally friendly, and low-cost method for producing colloidal TCE-AgNPs with promising applications in advanced clinical settings against broad-spectrum biofilm-forming antibiotic-resistant bacteria and candida strains.

Extreme deformability of insect cell membranes is governed by phospholipid scrambling.

Organization of dynamic cellular structure is crucial for a variety of cellular functions. In this study, we report that Drosophila and Aedes have highly elastic cell membranes with extremely low membrane tension and high resistance to mechanical stress. In contrast to other eukaryotic cells, phospholipids are symmetrically distributed between the bilayer leaflets of the insect plasma membrane, where phospholipid scramblase (XKR) that disrupts the lipid asymmetry is constitutively active. We also demonstrate that XKR-facilitated phospholipid scrambling promotes the deformability of cell membranes by regulating both actin cortex dynamics and mechanical properties of the phospholipid bilayer. Moreover, XKR-mediated construction of elastic cell membranes is essential for hemocyte circulation in the Drosophila cardiovascular system. Deformation of mammalian cells is also enhanced by the expression of Aedes XKR, and thus phospholipid scrambling may contribute to formation of highly deformable cell membranes in a variety of living eukaryotic cells.

Mechanosensitive ion channels in cell migration.

Cellular processes are initiated and regulated by different stimuli, including mechanical forces. Cell membrane mechanosensors represent the first step towards the conversion of mechanical stimuli to a biochemical or electrical response. Mechanosensitive (MS) ion channels form a growing family of ion gating channels that respond to direct physical force or plasma membrane deformations. A number of calcium (Ca2+) permeable MS channels are known to regulate the initiation, direction, and persistence of cell migration during development and tumour progression. While the evidence that links individual MS ion channels to cell migration is growing, a unified analysis of the molecular mechanisms regulated downstream of MS ion channel activation is lacking. In this review, we describe the MS ion channel families known to regulate cell migration. We discuss the molecular mechanisms that act downstream of MS ion channels with an emphasis on Ca2+ mediated processes. Finally, we propose the future directions and impact of MS ion channel activity in the field of cell migration.

Evaluation of erythrocyte deformability in patients with hypertension

Background. In the longterm course of hypertension, changes occur not only at the systemic, but also at the membrane level. The predominance of red blood spherocytic cells in hypertension, due to the low deformability of their membrane, can lead to further deterioration of the perfusion of the microcirculatory bed and the development of oxygen starvation of tissues. It is important to assess the extent of gas exchange disorders in organs and tissues in hypertension as early as possible in order to choose the correct and timely treatment strategy for patients with this disease. Currently, in order to assess the ability of red blood cells to deformability in the conditions of clinical units, it is necessary to have special equipment, certain conditions and specialist qualifications.Design and methods. We have developed a method of evaluating deformability of erythrocytes in hypertensive patients. The method includes measuring the patient’s blood pressure, blood sampling, lipidogram, measuring red blood cell parameters on a hematological analyzer with the calculation of the red blood cell sphericity index, and calculating the indicator of the red blood cell membrane deformability by the proposed formula.Conclusions. This method allows of timely diagnostics of the systemic microcirculation abnormality in hypertensive patients. The proposed method is intended for pathophysiologists, physicians, cardiologists, specialists of clinical laboratory diagnostics, it can also be applied for research purposes.

Ohmic heating increases inactivation and morphological changes of Salmonella sp. and the formation of bioactive compounds in infant formula

The effect of ohmic heating (OH) (50, 55, and 60 °C, 6 V/cm) on the inactivation kinetics (Weibull model) and morphological changes (scanning electron microscopy and flow cytometry) of Salmonella spp. in infant formula (IF) was evaluated. In addition, thermal load indicators (hydroxymethylfurfural and whey protein nitrogen index, HMF, and WPNI) and bioactive compounds (DPPH, total phenolics, ACE, α-amylase, and α-glucosidase inhibitory activities) were also studied. OH presented a more intense inactivation rate than conventional heating, resulting in a reduction of about 5 log CFU per mL at 60 °C in only 2.91 min, being also noted a greater cell membrane deformation, higher formation of bioactive compounds, and lower values for the thermal load parameters. Overall, OH contributed to retaining the nutritional value and improve food safety in IF processing.