Changes In Membrane Permeability Research Articles

Comparative physiological and transcriptomic analysis of sono-biochemical control over post-acidification of Lactobacillus delbrueckii subsp. bulgaricus

Thermosonication (UT) prestress treatments combining with varied fermentation patterns has been revealed as an effective method to regulate post-acidification as exerted by Lactobacillus delbrueckii subsp. bulgaricus (L. delbrueckii), but sono-biochemical controlling mechanisms remain elusive. This study employed physiological and transcriptomic analysis to explore the response mechanism of L. delbrueckii to UT-induced microstress (600 W, 33 kHz, 10 min). UT stress-induced inhibition of acidification of L. delbrueckii during (post)-fermentation was first confirmed, relying on the UT process parameters such as stress exposure duration and UT power. The significantly enhanced membrane permeability in cells treated by 600 W for 10 min than the microbes stressed by 420 W for 20 min suggested the higher dependence of UT-derived stresses on the treatment durations, relative to the ultrasonic powers. In addition, ultrasonication treatment-induced changes in cell membrane integrity enhanced and/or disrupted permeability of L. delbrueckii, resulting in an imbalance in intracellular conditions associated with corresponding alterations in metabolic behaviors and fermentation efficiencies. UT-prestressed inoculum exhibited a 21.46% decrease in the membrane potential during the lag phase compared to untreated samples, with an intracellular pH of 5.68 ± 0.12, attributed to the lower activities of H+-ATPase and lactate dehydrogenase due to UT stress pretreatments. Comparative transcriptomic analysis revealed that UT prestress influenced the genes related to glycolysis, pyruvate metabolism, fatty acid synthesis, and ABC transport. The genes encoding 3-oxoacyl-[acyl-carrier-protein] reductases I, II, and III, CoA carboxylase, lactate dehydrogenase, pyruvate oxidase, glucose-6-phosphate isomerase, and glycerol-3-phosphate dehydrogenase were downregulated, thus identifying the relevance of the UT microstresses-downregulated absorption and utilization of carbohydrates with the attenuated fatty acid production and energy metabolisms. These findings could contribute to provide a better understanding of the inactivated effects on the post-acidification of L. delbrueckii by ultrasonic pretreatments, thus providing theoretical basis for the targeted optimization of acidification inhibition efficiencies for yogurt products during chilled preservation processes.

Oxidized guanosines induce mitochondrial dysfunction and loss of viability in β-cells

The production of reactive oxygen species and oxidative stress promote β-cell dysfunction and impair insulin secretion, thereby contributing to the pathogenesis of type 2 diabetes mellitus (T2DM). The nucleobase guanine is highly sensitive to oxidation, which results in the formation of 8-oxoguanosine (8oxoG) and 8-oxodeoxyguanosine (8oxodG). The urinary excretion of 8oxoG is associated with the risk of mortality in people with T2DM, including from diabetic complications such as cardiovascular disease. However, the cellular mechanisms responsible for this association are poorly defined. Therefore, in this study, we examined the effect of 8oxoG, 8oxodG and other oxidized guanosine derivatives, on the INS-1E β-cell line. Exposure of INS-1E cells to 8oxoG and 8oxodG decreased metabolic activity and promoted cell death by apoptosis. The change in cell viability was similar to that induced by treatment of INS-1E cells with the inflammatory cytokines interleukin 1β (Il-1β) and tumour necrosis factor α (TNFα). Changes in mitochondrial membrane permeability and superoxide radical formation were also observed with 8oxoG, but there was no significant change in the oxidation state of mitochondrial cytochromes or hydrogen peroxide levels in the INS-1E cells. Interestingly, exposure to 8oxoG and 8-oxodG also increased the mRNA expression of stress response genes, including NADPH dehydrogenase quinone 1 (NQO1), and thioredoxin-interacting protein (TXNIP). Together, these results support a potential role of oxidized guanosine derivatives in the induction of β-cell dysfunction, which could be relevant to the pathogenesis of T2DM.

Isoquercitrin alleviates pirarubicin-induced cardiotoxicity in vivo and in vitro by inhibiting apoptosis through Phlpp1/AKT/Bcl-2 signaling pathway.

Introduction: Due to the cardiotoxicity of pirarubicin (THP), it is necessary to investigate new compounds for the treatment of THP-induced cardiotoxicity. Isoquercitrin (IQC) is a natural flavonoid with anti-oxidant and anti-apoptosis properties. Thus, the present study aimed to investigate the influence of IQC on preventing the THP-induced cardiotoxicity in vivo and in vitro. Methods: The optimal concentration and time required for IQC to prevent THP-induced cardiomyocyte damage were determined by an MTT assay. The protective effect was further verified in H9c2 and HCM cells using dichlorodihydrofluorescein diacetate fluorescent probes, MitoTracker Red probe, enzyme-linked immunosorbent assay, JC-1 probe, and real time-quantitative polymerase chain reaction (RT-qPCR). Rats were administered THP to establish cardiotoxicity. An electrocardiogram (ECG) was performed, and cardiac hemodynamics, myocardial enzymes, oxidative stress indicators, and hematoxylin-eosin staining were studied. Voltage-dependent anion channel 1 (VDAC1), adenine nucleotide translocase 1 (ANT1), and cyclophilin D (CYPD) were detected by qRT-PCR, and the Phlpp1/AKT/Bcl-2 axis proteins were detected by western blot, confirming that IQC markedly increased cell viability and superoxide dismutase (SOD) levels, diminished the levels of ROS and MDA, and elevated mitochondrial function and apoptosis in vivo and in vitro. Results: Results showed that IQC reduced THP-induced myocardial histopathological injury, electrocardiogram (ECG) abnormalities, and cardiac dysfunction in vivo. IQC also decreased serum levels of MDA, BNP, CK-MB, c-TnT, and LDH, while increasing levels of SOD and GSH. We also found that IQC significantly reduced VDAC1, ANT1, and CYPD mRNA expression. In addition, IQC controlled apoptosis by modulating Phlpp1/AKT/Bcl-2 signaling pathways. IQC markedly increased H9c2 and HCM cell viability and SOD levels, diminished the levels of ROS and MDA, and elevated mitochondrial function in H9c2 and HCM cells to defend against THP-induced cardiomyocyte apoptosis in vitro. The AKT inhibitor IMQ demonstrated that IQC lacked antioxidant and anti-apoptotic properties. Moreover, our data showed that IQC regulates Phlpp1 expression, thereby influencing the expression levels of p-AKT, cytochrome c, caspase-3, caspase-9, Bcl-2, and Bax. Discussion: In conclusion, our results indicate that IQC protects the changes in mitochondrial membrane permeability in cardiomyocytes by regulating the Phlpp1/AKT/Bcl-2 signaling pathway, inhibits the release of cytc from the mitochondrial inner membrane to the cytoplasm, forms apoptotic bodies, induces cell apoptosis, and reduces THP induced cardiotoxicity.

Synthesis and antibacterial properties of alkyl substituted sulfonium salt

The development of new antibacterial agents is particularly important in the battle against pathogenic microorganisms. In this study, sulfonium ions were used as the structural core to synthesize alkyl-substituted ionic compounds as antibacterial agents. The antimicrobial activity of sulfonium ionic compounds against Escherichia coli and Staphylococcus aureus was analyzed by measurement of the minimum inhibitory concentration and minimum bactericidal concentration. The effects of sulfonium salts on cell membrane integrity and permeability were investigated by detecting the extracellular proteins leakage of E. coli and S. aureus upon contact treatment, and observing the bacteria’s ultrastructural changes with transmission electron microscopy. The results showed that all the sulfonium salts exhibited resistant activity. Sulfonium salt with alkyl chain length of 16 carbon presented the strongest resistance with MIC of 30 and 3.75 μmol/L, and MBC of 120 and 60 μmol/L against E. coli and S. aureus, respectively. After treatment with sulfonium salts, the permeability of the membrane of E. coli and S. aureus cells changed, and the exudation of extracellular proteins increased significantly. The transmission electron microscope showed that the surface of the bacteria had shrunk and the cell walls had burst. The group of sulfonium salt compounds can destroy the integrity of cell membrane and change membrane permeability to achieve antibacterial purposes.

Co-exposure to pentachlorophenol (PCP) and cadmium (Cd) triggers apoptosis-like cell death in Eschericia coli

Pentachlorophenol (PCP) - cadmium (Cd) complex pollution has been identified as a form of persistent soil pollution in south China, exerting detrimental impacts on the indigenous soil bacterial communities. Hence, it is worthwhile to investigate whether and how bacterial populations alter in response to these pollutants. In this study, Escherichia coli was used as a model bacterium. Results showed that PCP exposure caused bacterial cell membrane permeability changes, intracellular ROS elevation, and DNA fragmentation, and triggered apoptosis-like cell death at low exposure concentration and necrosis at high exposure concentration. Cd exposure caused severe oxidative damage and cell necrosis in the tested bacterial strain. The co-exposure to PCP and Cd elevated the ROS level, stimulated the bacterial caspase activity, and induced DNA fragmentation, thereby leading to an apoptosis-like cell death. In conclusion, PCP-Cd complex pollution can cause bacterial population to decrease through apoptosis-like cell death pathway. However, it is worth noting that the subpopulation survives under the complex pollution stress.

Antibacterial activity and action mode of crude bacteriocin C2-1 from Ligilactobacillus salivarius C2-1 against Listeria monocytogenes CICC 21633

The potential use of Ligilactobacillus salivarius-derived bacteriocin for the control of L. monocytogenes was investigated. The purpose of the study was to explore the antibacterial action mode of crude bacteriocin C2-1 from Ligilactobacillus salivarius C2-1 against Listeria monocytogenes CICC 21633. The inhibition zone diameter of crude bacteriocin C2-1 was 27.82 ± 0.3 mm against L. monocytogenes CICC 21633, and the minimum inhibitory concentration (MIC) of bacteriocin C2-1was 13.98 μg/mL. Bacteriocin C2-1 significantly inhibited the normal growth of L. monocytogenes CICC21633, is sensitive to proteinase K, trypsin, and pepsin, and has good thermal stability and acid tolerance. The antibacterial mode of bacteriocin C2-1 against L. monocytogenes CICC 21633 was discussed based on changes in cell membrane permeability, integrity, and morphological structure of L. monocytogenes CICC 21633 by measuring the conductivity, UV-absorbing substance content and the observation via scanning electron microscopy, respectively. These results demonstrated that bacteriocin C2-1 affected the cell membrane permeability and integrity of L. monocytogenes CICC 21633, resulting in intracellular material leakage. Furthermore, bacteriocin-producing genes were identified in the genome sequence using antiSMASH and BAGEL4 assays. Bacteriocin C2-1 might be a good biological food preservative to prevent L. monocytogenes infestation.

Gram-Positive Bacterial Membrane-Based Biosensor for Multimodal Investigation of Membrane-Antibiotic Interactions.

As membrane-mediated antibiotic resistance continues to evolve in Gram-positive bacteria, the development of new approaches to elucidate the membrane properties involved in antibiotic resistance has become critical. Membrane vesicles (MVs) secreted by the cytoplasmic membrane of Gram-positive bacteria contain native components, preserving lipid and protein diversity, nucleic acids, and sometimes virulence factors. Thus, MV-derived membrane platforms present a great model for Gram-positive bacterial membranes. In this work, we report the development of a planar bacterial cytoplasmic membrane-based biosensor using MVs isolated from the Bacillus subtilis WT strain that can be coated on multiple surface types such as glass, quartz crystals, and polymeric electrodes, fostering the multimodal assessment of drug-membrane interactions. Retention of native membrane components such as lipoteichoic acids, lipids, and proteins is verified. This biosensor replicates known interaction patterns of the antimicrobial compound, daptomycin, with the Gram-positive bacterial membrane, establishing the applicability of this platform for carrying out biophysical characterization of the interactions of membrane-acting antibiotic compounds with the bacterial cytoplasmic membrane. We report changes in membrane viscoelasticity and permeability that correspond to partial membrane disruption when calcium ions are present with daptomycin but not when these ions are chelated. This biomembrane biosensing platform enables an assessment of membrane biophysical characteristics during exposure to antibiotic drug candidates to aid in identifying compounds that target membrane disruption as a mechanism of action.

Investigating the Role of Extracellular Matrix Stiffness in Modulating the Ferroptosis Process in Hepatocellular Carcinoma Cells via Scanning Electrochemical Microscopy.

Extracellular matrix (ECM) stiffness modulates a variety of cellular processes, including ferroptosis, a process with significant potential implications for hepatocellular carcinoma (HCC) fibrosis and cirrhosis. However, the exact relationship between ECM stiffness and HCC ferroptosis is yet unclarified, partially due to the lack of in situ information on key parameters of the ferroptosis process of living HCC cells. This study pioneers the use of in vitro mechanical microenvironment models of HCC and the scanning electrochemical microscopy (SECM) technique for understanding this interplay. We first cultured HuH7 cells on 4.0, 18.0, and 44.0 kPa polyacrylamide (PA) gels to simulate early, intermediate, and advanced HCC ECM stiffness, respectively. Then, we used SECM to in situ monitor changes in cell membrane permeability, respiratory activity, and reactive oxygen species (ROS) levels of erastin-induced HuH7 cells on PA gels, finding that increasing ECM stiffness potentiates ferroptosis, including increased membrane permeabilization and H2O2 release as well as reduced respiratory activity. Through further transcriptome sequencing and molecular biology measurements, we identified a critical role for focal adhesion kinase (FAK)-mediated yes-associated protein (YAP) in regulating the ferroptosis process dependent on ECM stiffness, which provides novel insights into the mechanical regulation of ferroptosis in HCC cells and may pave the way for innovative therapeutic strategies.

Neher and Sakmann: Single Ion Channels.

Most biological functions have their basis in a rapid change in cell membrane permeability. Hodgkin and Huxley showed regulation of the flow of molecules and ions between the nerve cell and its environment (Nobel Prize 1963), by recording macroscopic currents. Two Germans Neher and Sakmann showed that specific ion channels actually exist, and specific membrane proteins act as gates or agents for active transport regulating in physiological and pathological processes.

Combination of a pH-responsive peptide amphiphile and a conventional antibiotic in treating Gram-negative bacteria

BackgroundClinical treatments ofgastric infections using antibiotics suffer from the undesired killing of commensal bacteria and emergence of antibiotic resistance. It is desirable to develop pH-responsive antimicrobial peptides (AMPs) that kill pathogenic bacteria such as H. pyloriand resistant E. coli under acidic environment with minimal impact to commensal bacteria whilst not causing antibiotic resistance. ExperimentsUsing a combined approach of cell assays, molecular dynamics (MD) simulations and membrane models facilitating biophysical and biochemical measurements including small angle neutron scattering (SANS), we have characterized the pH-responsive physiochemical properties and antimicrobial performance of two amphiphilic AMPs, GIIKDIIKDIIKDI-NH2 and GIIKKIIDDIIKKI-NH2 (denoted as 3D and 2D, respectively), that were designed by selective substitutions of cationic residues of Lys (K) in the extensively studied AMP G(IIKK)3I-NH2 with anionic residue Asp (D). FindingsWhilst 2D kept non-ordered coils across the entire pH range studied, 3D displayed a range of secondary structures when pH was shifted from basic to acidic, with distinct self-assembly into nanofibers in aqueous environment. Further experimental and modeling studies revealed that the AMPs interacted differently with the inner and outer membranes of Gram-negative bacteria in a pH-responsive manner and that the structural features characterized by membrane leakage and intramembrane nanoaggregates revealed from fluorescence spectroscopy and SANS were well linked to antimicrobial actions. Different antimicrobial efficacies of 2D and 3D were underlined by the interplay between their ability to bind to the outer membrane lipid LPS (lipopolysaccharide), outer membrane permeability change and inner membrane depolarization and leakage. Furthermore, AMP’s binding with the inner membrane under acidic condition caused both the dissipation of membrane potential (Δψ) and the continuous dissipation of transmembrane ΔpH, with Δψ and ΔpH being the key components of the proton motive force. Combinations of antibiotic (Minocycline) with the pH-responsive AMP generated the synergistic effects against Gram-negative bacteria only under acidic condition. These features are crucial to target applications to gastric infections, anti-acne and wound healing.

PH-responsive bentonite nanoclay carriers control the release of benzothiazolinone to restrain bacterial wilt disease

Ralstonia solanacearum (R. solanacearum) is one of the most devastating pathogens in terms of losses in agricultural production. Bentonite (Bent) is a promising synergistic agent used in development of effective and environmentally friendly pesticides against plant disease. However, the synergistic mechanism of Bent nanoclays with benzothiazolinone (BIT) against R. solanacearum is unknown. In this work, acid-functionalized porous Bent and cetyltrimethylammonium bromide (CTAB) were employed as the core nanoclays, and BIT was loaded into the clay to form BIT-loaded CT-Bent (BIT@CT-Bent) for the control of bacterial wilt disease. BIT@CT-Bent exhibited pH-responsive release behavior that fit the Fickian diffusion model, rapidly releasing BIT in an acidic environment (pH = 5.5). The antibacterial effect of BIT@CT-Bent was approximately 4 times greater than that of the commercial product BIT, and its biotoxicity was much lower than that of BIT under the same conditions. Interestingly, R. solanacearum attracted BIT@CT-Bent into the nanocomposites and induced cytoplasmic leakage and changes in membrane permeability, indicating an efficient and synergistic bactericidal effect that rapidly reduced bacterial density. In addition, BIT@CT-Bent significantly inhibited R. solanacearum biofilm formation and swimming activity, by suppressing the expression of phcA, solR and vsrC. Indeed, exogenous application of BIT@CT-Bent significantly suppressed the virulence of R. solanacearum on tobacco plants, with control effect of 75.48%, 72.08% and 66.08% at 9, 11 and 13 days after inoculation, respectively. This study highlights the potential of using BIT@CT-Bent as an effective, eco-friendly bactericide to control bacterial wilt diseases and for the development of sustainable crop protection strategies.

Synthesizing Carbon Quantum Dots via Hydrothermal Reaction to Produce Efficient Antibacterial and Antibiofilm Nanomaterials.

This study aimed to synthesize antibacterial carbon quantum dots (SP-CDs) from polyethyleneimine and spermidine via hydrothermal reaction. It was revealed that SP-CDs, with small size (7.18 nm) and high positive charge (+31.15 mV), had good fluorescence properties and lots of amino groups on their surfaces. The inhibition effect of SP-CDs on Staphylococcus aureus was better than that towards Escherichia coli, and the SP-CDs also had an inhibitory effect on multi-drug-resistant E. coli. The mechanism of SP-CDs shows that the SP-CDs were adsorbed on the surface of the negatively charged cell membrane through electrostatic interaction. SP-CDs can cause changes in membrane permeability, resulting in a shift of the cell membrane from order to disorder and the decomposition of chemical components, followed by the leakage of cell contents, resulting in bacterial death. SP-CDs can also significantly inhibit biofilm formation, destroy mature biofilms and reduce the number of living cells. Moreover, SP-CDs had negligible antimicrobial resistance even after 18 generations of treatment. This study proves that SP-CDs effectively inhibit the proliferation of foodborne pathogens, providing new feasibility for the application of carbon-based nanomaterials in the food industry.

Tumor-targeting hydroxyapatite nanoparticles for remodeling tumor immune microenvironment (TIME) by activating mitoDNA-pyroptosis pathway in cancer

In recent years, immunotherapy has emerged as a promising strategy for treating solid tumors, although its efficacy remains limited to a subset of patients. Transforming non-responsive “cold” tumor types into immuno-responsive “hot” ones is critical to enhance the efficacy of immune-based cancer treatments. Pyroptosis, a programmed cell death mechanism, not only effectively eliminates tumor cells but also triggers a potent inflammatory response to initiate anti-tumor immune activities. This sheds light on the potential of pyroptosis to sensitize tumors to immune therapy. Hence, it is urgent to explore and develop novel treatments (e.g., nanomedicines) which are capable of inducing pyroptosis. In this study, we constructed tumor-targeting nanoparticles (CS-HAP@ATO NPs) by loading atorvastatin (ATO) onto chondroitin sulfate (CS) modified hydroxyapatite (HAP) nanoparticles (CS-HAP). CS was strategically employed to target tumor cells, while HAP exhibited the capacity to release calcium ions (Ca2+) in response to the tumor microenvironment. Moreover, ATO disrupted the mitochondrial function, leading to intracellular energy depletion and consequential changes in mitochondrial membrane permeability, followed by the influx of Ca2+ into the cytoplasm and mitochondria. CS and HAP synergetically augmented mitochondrial calcium overload, inciting the production of substantial amount of reactive oxygen species (ROS) and the subsequent liberation of oxidized mitochondrial DNA (OX-mitoDNA). This intricate activation process promoted the assembly of inflammasomes, most notably the NLRP3 inflammasome, followed by triggering caspase-1 activation. The activated caspase-1 was able to induce gasderminD (GSDMD) protein cleavage and present the GSDM-N domain, which interacted with phospholipids in the cell membrane. Then, the cell membrane permeability was raised, cellular swelling was observed, and abundant cell contents and inflammatory mediators were released. Ultimately, this orchestrated sequence of events served to enhance the anti-tumor immunoresponse within the organism.

Three snake venoms from Bothrops genus induced apoptosis and cell cycle arrest in K562 human leukemic cell line

Cancer is indisputably one of the leading causes of death worldwide. Snake venoms are a potential source of bioactive compounds, complex mixtures constituted mainly of proteins and peptides with several pharmacological possibilities, including the potential to inhibit tumoral cell growth. In the present study, it was evaluated the antitumor effect of crude venom of Bothrops erythromelas (BeV), Bothrops jararaca (from Southern and Southeastern- BjsV and BjsdV, respectively) and Bothrops alternatus (BaV) in in vitro Chronic myeloid leukemia (CML) cancer cell line model. After 24 h of cell exposure to 10 and 50 μg/mL, BjsV, BjsdV, and BaV exerted a decrease in cell viability in both concentrations. BeV was not cytotoxic and, therefore wasn’t chosen for further mechanism of action investigation. Furthermore, morphological alterations show modification typical of apoptosis. Also, was observes a significant cell cycle arrest in the S phase by BjsdV and BaV treatment. Flow cytometry evidenced the involvement of changes in the cell membrane permeability and the mitochondrial function by BjsV and BjsdV, corroborating with the triggering of the apoptotic pathway by the venom administration. BjsV, BjsdV, and BaV also led to extensive DNA damage and were shown to modulate the gene expression of transcripts related to the cell cycle progression and suppress the expression of the BCR-ABL1 oncogene. Altogether, these findings suggest that the venoms trigger the apoptosis pathway due to mitochondrial damage and cell cycle arrest, with modulation of intracellular pathways important for CML progression. Thus, indicating the pharmacological potential of these venoms in the development of new antitumoral compounds.

Unraveling the mechanistic insights of sophorolipid-capped gold nanoparticle-induced cell death in Vibrio cholerae.

Cholera is one of the leading causes of mortality and morbidity worldwide. The treatment of cholera includes rehydration therapy, often combined with the administration of antibiotics (in severe cases). With the emergence and rapid spread of antimicrobial resistance, such microbial pathogens have become a compelling medical problem and a global threat. To combat the resistance to antibiotics, there is an urgent need for the discovery of novel and potent antimicrobial agents. The discovery of antimicrobial nanoparticles as an alternative to the existing antimicrobial regime has increased the hope for its use as one of the most promising tools against an array of microbial pathogens, including multidrug-resistant bacteria. Our recent report demonstrated that sophorolipid-capped gold nanoparticles (AuNPs-SL) exhibit potent antibacterial activity against Vibrio cholerae; however, the killing mechanism remained obscure. Metal nanoparticle-mediated killing of microbes occurs through non-specific mechanisms. To develop antimicrobial nanoparticles with better efficacy, knowledge of their specific mechanism of action is essential. In this work, we deduced the mechanistic insights of AuNPs-SL mediated cell death of V. cholerae. We observed that AuNPs-SL treatment evokes reactive oxygen species (ROS) formation. The surge in the ROS level triggers the overexpression of ROS-responsive genes, depolarization of the membrane, change in membrane permeability and leakage of intracellular proteins and DNA, depletion of ATP levels in the cell, DNA damage, and subsequent cell death. This study shows the possibility of use of AuNPs-SL as an alternative potential antimicrobial agent. IMPORTANCE Vibrio cholerae, a Gram-negative bacterium, is the causative agent of a fatal disease, "cholera." Prevention of cholera outbreak is possible by eliminating the bacteria from the environment. However, antimicrobial resistance developed in microorganisms has posed a threat and challenges to its treatment. Application of nanoparticles is a useful and effective option for the elimination of such microorganisms. Metal-based nanopaticles exhibit microbial toxicity through non-specific mechanisms. To prevent resistance development and increase antibacterial efficiency, rational designing of nanoparticles is required. Thus, knowledge on the exact mechanism of action of nanoparticles is highly essential. In this study, we explore the possible mechanisms of antibacterial activity of AuNPs-SL against V. cholerae. We show that the interaction of AuNPs-SL with V. cholerae enhances ROS production and membrane depolarization, change in permeability, and leakage of intracellular content. This action leads to the depletion of cellular ATP level, DNA damage, and subsequent cell death.

Dynamic calcium-mediated stress response and recovery signatures in the fungal pathogen, Candida albicans.

Intracellular calcium signaling plays an important role in the resistance and adaptation to stresses encountered by fungal pathogens within the host. This study reports the optimization of the GCaMP fluorescent calcium reporter for live-cell imaging of dynamic calcium responses in single cells of the pathogen, Candida albicans, for the first time. Exposure to membrane, osmotic or oxidative stress generated both specific changes in single cell intracellular calcium spiking and longer calcium transients across the population. Repeated treatments showed that calcium dynamics become unaffected by some stresses but not others, consistent with known cell adaptation mechanisms. By expressing GCaMP in mutant strains and tracking the viability of individual cells over time, the relative contributions of key signaling pathways to calcium flux, stress adaptation, and cell death were demonstrated. This reporter, therefore, permits the study of calcium dynamics, homeostasis, and signaling in C. albicans at a previously unattainable level of detail.

Investigating synergism and mechanism during sequential inactivation of Staphylococcus aureus with ultrasound followed by UV/peracetic acid

This study explored the inactivation of Staphylococcus aureus (S. aureus) by ultrasound (US) and peracetic acid (PAA) coupling with UV simultaneously (US/PAA/UV) or sequentially (US→PAA/UV) for the strengthened disinfection. The result showed that US→PAA/UV system had excellent inactivation performance with 5.05-log in a short time. Besides US, UV, PAA and free radicals, the contribution of the synergy of all components to the entire disinfection were obvious under US→PAA/UV system. The inactivation performance of S. aureus significantly decreased with the increase of humic acid (HA) concentration and pH; however, the rising temperature contributes to the enhancement of the inactivation efficiency under the US→PAA/UV system. The disinfection mechanism includes a decrease of cell agglomeration, a loss of intracellular substance, and changes of cell structure and membrane permeability, as evidenced through a nanoparticle size analyzer, scanning electron microscope (SEM), transmission electron microscope (TEM) and laser confocal microscopy (LSCM). Furthermore, the inactivation efficiency of the US→PAA/UV system for the total bacteria from actual sewage (the untreated inflow) was high, which reached 3.86-log. In general, the pretreatment of US combined with UV/PAA showed a promising application in the rapid disinfection of sewage.

Exploring Nitrogen-Functionalized Graphene Composites for Urinary Catheter Applications.

Graphene has been broadly studied, particularly for the fabrication of biomedical devices, owing to its physicochemical and antimicrobial properties. In this study, the antibiofilm efficacy of graphene nanoplatelet (GNP)-based composites as coatings for urinary catheters (UCs) was investigated. GNPs were functionalized with nitrogen (N-GNP) and incorporated into a polydimethylsiloxane (PDMS) matrix. The resulting materials were characterized, and the N-GNP/PDMS composite was evaluated against single- and multi-species biofilms of Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Both biofilm cell composition and structure were analyzed. Furthermore, the antibacterial mechanisms of action of N-GNP were explored. The N-GNP/PDMS composite showed increased hydrophobicity and roughness compared to PDMS. In single-species biofilms, this composite significantly reduced the number of S. aureus, P. aeruginosa, and K. pneumoniae cells (by 64, 41, and 29%, respectively), and decreased S. aureus biofilm culturability (by 50%). In tri-species biofilms, a 41% reduction in total cells was observed. These results are aligned with the outcomes of the biofilm structure analysis. Moreover, N-GNP caused changes in membrane permeability and triggered reactive oxygen species (ROS) synthesis in S. aureus, whereas in Gram-negative bacteria, it only induced changes in cell metabolism. Overall, the N-GNP/PDMS composite inhibited biofilm development, showing the potential of these carbon materials as coatings for UCs.

Effects of Nitro-Oxidative Stress on Biomolecules: Part 1-Non-Reactive Molecular Dynamics Simulations.

Plasma medicine, or the biomedical application of cold atmospheric plasma (CAP), is an expanding field within plasma research. CAP has demonstrated remarkable versatility in diverse biological applications, including cancer treatment, wound healing, microorganism inactivation, and skin disease therapy. However, the precise mechanisms underlying the effects of CAP remain incompletely understood. The therapeutic effects of CAP are largely attributed to the generation of reactive oxygen and nitrogen species (RONS), which play a crucial role in the biological responses induced by CAP. Specifically, RONS produced during CAP treatment have the ability to chemically modify cell membranes and membrane proteins, causing nitro-oxidative stress, thereby leading to changes in membrane permeability and disruption of cellular processes. To gain atomic-level insights into these interactions, non-reactive molecular dynamics (MD) simulations have emerged as a valuable tool. These simulations facilitate the examination of larger-scale system dynamics, including protein-protein and protein-membrane interactions. In this comprehensive review, we focus on the applications of non-reactive MD simulations in studying the effects of CAP on cellular components and interactions at the atomic level, providing a detailed overview of the potential of CAP in medicine. We also review the results of other MD studies that are not related to plasma medicine but explore the effects of nitro-oxidative stress on cellular components and are therefore important for a broader understanding of the underlying processes.

Low-intensity pulsed ultrasound in obstetrics and gynecology: advances in clinical application and research progress.

In the past decade, research on ultrasound therapy in obstetrics and gynecology has rapidly developed. Currently, high-intensity ultrasound has been widely used in clinical practice, while low-intensity ultrasound has gradually emerged as a new trend of transitioning from pre-clinical research to clinical applications. Low-intensity pulsed ultrasound (LIPUS), characterized by a non-invasive low-intensity pulse wave stimulation method, employs its non-thermal effects to achieve safe, economical, and convenient therapeutic outcomes. LIPUS converts into biochemical signals within cells through pathways such as cavitation, acoustic flow, and mechanical stimulation, regulating molecular biological mechanisms and exerting various biological effects. The molecular biology mechanisms underlying the application of LIPUS in obstetrics and gynecology mainly include signaling pathways, key gene expression, angiogenesis, inflammation inhibition, and stem cell differentiation. LIPUS plays a positive role in promoting soft tissue regeneration, bone regeneration, nerve regulation, and changes in cell membrane permeability. LIPUS can improve the treatment benefit of premature ovarian failure, pelvic floor dysfunction, nerve damage caused by intrauterine growth restriction, ovariectomized osteoporosis, and incomplete uterine involution through the above biological effects, and it also has application value in the adjuvant treatment of malignant tumors such as ovarian cancer and cervical cancer. This study outlines the biological mechanisms and applications of LIPUS in treating various obstetric and gynecologic diseases, aiming to promote its precise application and provide a theoretical basis for its use in the field.