The impact of probiotic cell-free metabolites in MDR Pseudomonas aeruginosa: antibacterial properties and effect on antibiotic resistance genes expression.

There is a significant demand for novel antibacterial agents against multidrug-resistant (MDR) gram-negative bacteria. Recently, probiotics have been noted for their antibacterial properties against various pathogens. This study aimed to investigate the effects of probiotic cell-free supernatants on MDR Pseudomonas aeruginosa. Clinical isolates demonstrating the highest degree of antibiotic resistance were chosen, and the antibacterial effect of probiotic metabolites was evaluated using an agar-well diffusion assay. In addition, the effect of probiotics on the expression of resistance genes was evaluated using real-time PCR. The CFS was assessed using GC-MS to determine the antibacterial compounds. The supernatants inhibited the growth of the isolates (P < 0.0001); however, there was no noticeable difference in the effectiveness of the probiotics. In addition, the supernatants decreased the expression levels of mexD, mexB, mexF, and ampC, and an increase in oprD was observed in some groups. After the assessment of Lactobacillus acidophilus by GC-MS, antibacterial compounds, such as acetamide, nonadecane, 9-methyl, and tetradecane, were determined. Our findings showed that probiotic metabolites can effectively inhibit the growth of MDR P. aeruginosa. Gene expression analysis also revealed that the mechanism of antibacterial action was most likely related to the regulation of efflux pumps.

Homo-oligomerization of transmembrane α-domain of integrin.

Integrins contribute to form focal adhesions complex. Therefore, simulation of integrin interactions can be helpful in clarifying the mechanism of focal adhesion formation. Interactions of integrins can also initiate signal transduction in the focal adhesions. Since integrins contain α and ß subunits that are separated in an active state, studying both subunits separately is crucial, since, in the active state of integrins, the distance between these subunits is long enough that they do not influence one another significantly. Thus, this study aims to investigate the tendency of α subunits of integrins to form homodimers. All simulations were carried out via MARTINI coarse grain (CG) molecular dynamics technique. α subunits were placed in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid bilayer at a distance of 5 nm, and they were allowed to diffuse in the lipid bilayer. All simulations showed that α subunits have a tendency to form stable dimers.

Dynamic response of axonal microtubules under suddenly applied end forces.

Axon is a filament in neuronal system and axonal microtubules are bundles in axons. In axons, microtubules are coated with microtubule-associated protein tau, a natively unfolded profuse filamentous protein in the central nervous system. These proteins are responsible for the cross-linked structure of the axonal microtubule bundles. Through complimentary dimerization with other tau proteins, bridges are formed to nearby microtubules to create bundles. The transverse reinforcement of microtubules by cross-linking to the cytoskeleton has been shown to enhance their ability to bear compressive loads. Though microtubules are conventionally regarded as bearing compressive loads, in certain circumstances such as in traumatic stretch injury, they are placed in tension. We employ Standard Linear Solid, a viscoelastic model, to computationally simulate microtubules. This study investigates the dynamic response of two dimensional axonal microtubules under suddenly applied end forces. We obtain the results for steady state behavior of axonal microtubule for different forces.