Multiple Drug-Induced Stress Responses Inhibit Formation of Escherichia coli Biofilms

In most ecosystems, bacteria exist primarily as structured surface-associated biofilms that can be highly tolerant to antibiotics and thus represent an important health issue. Here, we explored drug repurposing as a strategy to identify new antibiofilm compounds, screening over 1,000 compounds from the Prestwick Chemical Library of approved drugs for specific activities that prevent biofilm formation by Escherichia coli. Most growth-inhibiting compounds, which include known antibacterial but also antiviral and other drugs, also reduced biofilm formation. However, we also identified several drugs that were biofilm inhibitory at doses where only a weak effect or no effect on planktonic growth could be observed. The activities of the most specific antibiofilm compounds were further characterized using gene expression analysis, proteomics, and microscopy. We observed that most of these drugs acted by repressing genes responsible for the production of curli, a major component of the E. coli biofilm matrix. This repression apparently occurred through the induction of several different stress responses, including DNA and cell wall damage, and homeostasis of divalent cations, demonstrating that biofilm formation can be inhibited through a variety of molecular mechanisms. One tested drug, tyloxapol, did not affect curli expression or cell growth but instead inhibited biofilm formation by suppressing bacterial attachment to the surface. IMPORTANCE The prevention of bacterial biofilm formation is one of the major current challenges in microbiology. Here, by systematically screening a large number of approved drugs for their ability to suppress biofilm formation by Escherichia coli, we identified a number of prospective antibiofilm compounds. We further demonstrated different mechanisms of action for individual compounds, from induction of replicative stress to disbalance of cation homeostasis to inhibition of bacterial attachment to the surface. Our work demonstrates the potential of drug repurposing for the prevention of bacterial biofilm formation and suggests that also for other bacteria, the activity spectrum of antibiofilm compounds is likely to be broad

Scanning cross-correlator for monitoring uniform 3D ellipsoidal laser beams

The specific features of experimental implementation of a cross-correlator with a scan rate above 1600 cm s(-1) and a spatial delay amplitude of more than 15 mm are considered. The possibility of measuring the width of femtosecond pulses propagating in a train 300 mu s in duration with a repetition rate of 1 MHz is demonstrated. A time resolution of 300 fs for the maximum time window of 50 ps is attained.The cross-correlator is aimed at testing 3D pulses of a laser driver of an electron photo-injector

Magnetic Properties of NiO Nano Particles: Contributions of the Antiferromagnetic and Ferromagnetic Subsystems in Different Magnetic Field Ranges up to 250 kOe

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The magnetic properties of antiferromagnetic NiO nanoparticles prepared by thermal decomposition of nickel hydroxocarbonate are investigated. According to the data of magnetization measurements in fields of up to 250 kOe, the magnetic moment linearly grows in strong fields, which is caused by the contribution of the antiferromagnetically ordered nanoparticle core, and the antiferromagnetic susceptibility corresponds to that of bulk polycrystalline NiO. This allowed the antiferromagnetic and ferromagnetic contributions to the total magnetic response of a sample to be quantitatively determined. The latter occurs due to the incomplete spin compensation in an antiferromagnetic nanoparticle caused by defects on its surface. It is demonstrated that to correctly determine the superparamagnetic blocking temperature, it is necessary to take into account the antiferromagnetic susceptibility of the particle core

Magnetic Properties of NiO Nano Particles: Contributions of the Antiferromagnetic and Ferromagnetic Subsystems in Different Magnetic Field Ranges up to 250 kOe

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The magnetic properties of antiferromagnetic NiO nanoparticles prepared by thermal decomposition of nickel hydroxocarbonate are investigated. According to the data of magnetization measurements in fields of up to 250 kOe, the magnetic moment linearly grows in strong fields, which is caused by the contribution of the antiferromagnetically ordered nanoparticle core, and the antiferromagnetic susceptibility corresponds to that of bulk polycrystalline NiO. This allowed the antiferromagnetic and ferromagnetic contributions to the total magnetic response of a sample to be quantitatively determined. The latter occurs due to the incomplete spin compensation in an antiferromagnetic nanoparticle caused by defects on its surface. It is demonstrated that to correctly determine the superparamagnetic blocking temperature, it is necessary to take into account the antiferromagnetic susceptibility of the particle core