Selenazolinium salts as "small molecule catalysts" with high potency against ESKAPE bacterial pathogens

In view of the pressing need to identify new antibacterial agents able to combat multidrug-resistant bacteria, we investigated a series of fused selenazolinium derivatives (1–8) regarding their in vitro antimicrobial activities against 25 ESKAPE-pathogen strains. Ebselen was used as reference compound. Most of the selenocompounds demonstrated an excellent in vitro activity against all S. aureus strains, with activities comparable to or even exceeding the one of ebselen. In contrast to ebselen, some selenazolinium derivatives (1, 3, and 7) even displayed significant actions against all Gram-negative pathogens tested. The 3-bromo-2-(1-hydroxy-1-methylethyl)[1,2]selenazolo[2,3-a]pyridinium chloride (1) was particularly active (minimum inhibitory concentrations, MICs: 0.31–1.24 µg/mL for MRSA, and 0.31–2.48 µg/mL for Gram-negative bacteria) and devoid of any significant mutagenicity in the Ames assay. Our preliminary mechanistic studies in cell culture indicated that their mode of action is likely to be associated with an alteration of intracellular levels of glutathione and cysteine thiols of different proteins in the bacterial cells, hence supporting the idea that such compounds interact with the intracellular thiolstat. This alteration of pivotal cysteine residues is most likely the result of a direct or catalytic oxidative modification of such residues by the highly reactive selenium species (RSeS) employed

Degradation of thin solar-sail membrane films under interplanetary medium

Thin metallized films are used in wide field applications of deployable membrane structures. Flexible and thin polyimide foils are covered by highly reflecting metallic surfaces. Unfortunately metals while interact with the solar wind particles indicate formation of tiny molecular hydrogen bubbles on their surface, i.e. ~0.4 μm in diameter. Such bubbles occur as a consequence of recombination processes of the solar protons and the metals’ electrons. Our aim was to experimentally confirm the formation of the bubbles under simulated conditions which mimic those present in the interplanetary space and find physical conditions, i.e. temperature of the membrane material, dose and kinetic energy of the incident protons at which the bubble formation process takes place. We have studied and select possible materials which may protect the metallized surfaces against the phenomenon. Three protection coatings have been chosen, the silicon- and the titanium- dioxide as well as titanate nanotubes. We have experimentally confirmed that metallic specimens exposed to flux of low energy protons (2.5 keV) indicate formation of tiny bubbles on their surface. High surface density of bubbles has its direct influence on the surface thermo-optical properties, which have a major impact on propulsion efficiency of any sail-craft

Modelling of the interactions between magnetic nanoparticles in aqueous solutions

The ability of magnetic nanoparticles and their aggregates to form larger structures or new materials is primarily based on the interactions between individual particles. The article analyzes the behavior of spherical nanoparticles Fe3O4 placed in an aqueous base solution as a result of their mutual interactions, i.e. repulsive (electrostatic forces) and attractive (van der Waals forces and dipolar magnetic forces) for the full range of parameter values. Considering the application of magnetic aqueous suspensions in industry or environmental research, the presented method allows for a preliminary selection of the parameters of the dispersed material and the solution so as to obtain a suspension with the desired properties

Effect of Magnetic Heating on Stability of Magnetic Colloids

Stable aqueous suspension of magnetic nanoparticles is essential for effective magnetic hyperthermia and other applications of magnetic heating in an alternating magnetic field. However, the alternating magnetic field causes strong agglomeration of magnetic nanoparticles, and this can lead to undesirable phenomena that deteriorate the bulk magnetic properties of the material. It has been shown how this magnetic field influences the distribution of magnetic agglomerates in the suspension. When investigating the influence of the sonication treatment on magnetic colloids, it turned out that the hydrodynamic diameter as a function of sonication time appeared to have a power-law character. The effect of magnetic colloid ageing on magnetic heating was discussed as well. It was shown how properly applied ultrasonic treatment could significantly improve the stability of the colloid of magnetic nanoparticles, ultimately leading to an increase in heating efficiency. The optimal sonication time for the preparation of the magnetic suspension turned out to be time-limited, and increasing it did not improve the stability of the colloid. The obtained results are important for the development of new materials where magnetic colloids are used and in biomedical applications

The Concept of Using 2D Self-Assembly of Magnetic Nanoparticles for Bioassays

It can be observed that magnetic iron-oxide nanoparticles are increasingly used in bioassay methods. This is due to their stability in aqueous solutions, ease of functionalization, biocompatibility and very low toxicity. Here, we show that the recent discovery of the ability of magnetic nanoparticles to self-assemble into 2D structures of ordered chains may be exploited for bioassays. This would open up the possibility of controlled immobilization of proteins, enzymes, DNA or RNA and other molecular systems on spatially ordered nanostructures. In this work, fluorescein was used as an example. Also shown is the possibility of using Raman spectroscopy to analyze material accumulated on such structures. The observed formation of regularly spaced chains of magnetic nanoparticles takes place during the drying process of a thin layer of magnetic liquid placed on an appropriately prepared low-density polyethylene (LDPE) film

Chorzy trudni typowiOstra niedrożność poprzednio zwężonego pnia lewej tętnicy wieńcowej powikłana masywną zatorowością płucną oraz zatrzymaniem krążenia

A case of a 53-year-old male with acute myocardial infarction complicated by cardiac arrest is presented. Due to neurological complications which were transient, the patient was not selected for primary angioplasty. Three days later his condition significantly improved and the patient was transferred to internal ward were he developed cardiogenic shock due to a massive pulmonary embolism. Thrombolysis and low molecular weight heparin were effective and the patient did well during subsequent hospitalisation period. Coronary angiography was performed 4 weeks from hospital admission and revealed a total left main coronary occlusion with good collateral circulation from the right coronary artery. Finally, the patient underwent successful CABG

Filtration of Nanoparticle Agglomerates in Aqueous Colloidal Suspensions Exposed to an External Radio-Frequency Magnetic Field

The study investigated the phenomenon of the fast aggregation of single-domain magnetic iron oxide nanoparticles in stable aqueous colloidal suspensions due to the presence of a radio-frequency (RF) magnetic field. Single-domain nanoparticles have specific magnetic properties, especially the unique property of absorbing the energy of such a field and releasing it in the form of heat. The localized heating causes the colloid to become unstable, leading to faster agglomeration of nanoparticles and, consequently, to rapid sedimentation. It has been shown that the destabilization of a stable magnetic nanoparticle colloid by the RF magnetic field can be used for the controlled filtration of larger agglomerates of the colloid solution. Two particular cases of stable colloidal suspensions were considered: a suspension of the bare nanoparticles in an alkaline solution and the silica-stabilized nanoparticles in a neutral solution. The obtained results are important primarily for biomedical applications and wastewater treatment

The Use of Ultra-Small Fe3O4 Magnetic Nanoparticles for Hydrothermal Synthesis of Fe3+-Doped Titanate Nanotubes

A method of the hydrothermal synthesis of Fe3+-doped titanate nanotubes (TNT) is reported in which the ultra-small Fe3O4 nanoparticles are used as the sources of Fe3+ ions. The magnetic nanoparticles with a diameter of about 2 nm are added during the washing stage of the hydrothermal procedure. During washing, they gradually degrade and at the same time, the titanate product is transformed into nanotubes. The obtained nanotubes were characterized by structural and magnetic measurements. It was found that, depending on the value of the external magnetic field, they may show the property of room temperature ferromagnetism, paramagnetism or they may be diamagnetic. It was also shown that the modified TNTs have greater photocatalytic activity compared to unmodified TNTs

Influence of Adriblastin and Bleomycin on Wistar rat mothers and fetus development

Introduction. Gestation is a very sensitive time both to mother and child. Any substance, factor, or environmental condition disturbing homeostasis may cause congenital defects, anomalies or even death. Teratology evaluates those potential factors and their influence. Also, medicinal products used during pregnancy may be teratogenic. Adriblastin, also known as Doxorubicin, and Bleomycin are widely used cytostatic drugs in oncology. Aim. Aim of this study was to evaluate the embryotoxic effects of Doxorubicin and Bleomycin in an animal model. Materials and methods. Fertilised Wistar rat females were given each drug intraperitoneally between the 8th and 15th gestation day, and compared to control group receiving placebo (distilled water, 0.9% NaCl). Another group received acetyl salicylic acid, as a model, well known teratogen. Changes in mothers’ weight from baseline, implantation of embryos, any discrepancies in mothers wombs and health as well as defects in fetuses were evaluated and compared. Fetus skeletons were stained by Dowson’s method to visualise bone defects. Results and conclusion. Both Adriblastin and Bleomycin were teratogenic, producing significantly more embryo absorptions, and fetal defects compared to placebo. The effects of the two cytostatics were similar to the model teratogen acetyl salicylic acid

Influence of Adriblastin and Bleomycin on Wistar rat mothers and fetus development

Introduction. Gestation is a very sensitive time both to mother and child. Any substance, factor, or environmental condition disturbing homeostasis may cause congenital defects, anomalies or even death. Teratology evaluates those potential factors and their influence. Also, medicinal products used during pregnancy may be teratogenic. Adriblastin, also known as Doxorubicin, and Bleomycin are widely used cytostatic drugs in oncology. Aim. Aim of this study was to evaluate the embryotoxic effects of Doxorubicin and Bleomycin in an animal model. Materials and methods. Fertilised Wistar rat females were given each drug intraperitoneally between the 8th and 15th gestation day, and compared to control group receiving placebo (distilled water, 0.9% NaCl). Another group received acetyl salicylic acid, as a model, well known teratogen. Changes in mothers’ weight from baseline, implantation of embryos, any discrepancies in mothers wombs and health as well as defects in fetuses were evaluated and compared. Fetus skeletons were stained by Dowson’s method to visualise bone defects. Results and conclusion. Both Adriblastin and Bleomycin were teratogenic, producing significantly more embryo absorptions, and fetal defects compared to placebo. The effects of the two cytostatics were similar to the model teratogen acetyl salicylic acid