Phase Diagram of Ternary Cholesterol/Palmitoylsphingomyelin/Palmitoyloleoyl-Phosphatidylcholine Mixtures: Spin-Label EPR Study of Lipid-Raft Formation

AbstractFor canonical lipid raft mixtures of cholesterol (chol), N-palmitoylsphingomyelin (PSM), and 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), electron paramagnetic resonance (EPR) of spin-labeled phospholipids—which is insensitive to domain size—is used to determine the ternary phase diagram at 23°C. No phase boundaries are found for binary POPC/chol mixtures, nor for ternary mixtures with PSM content <24 mol %. EPR lineshapes indicate that conversion from the liquid-disordered (Lα) to liquid-ordered (Lo) phase occurs continuously in this region. Two-component EPR spectra and several tie lines attributable to coexistence of gel (Lβ) and fluid phases are found for ternary mixtures with low cholesterol or low POPC content. For PSM/POPC alone, coexistence of Lα and Lβ phases occurs over the range 50−95.5 mol % PSM. A further tie line is found at 3 mol % chol with endpoints at 50 and ≥77 mol % PSM. For PSM/chol, Lβ−Lo coexistence occurs over the range 10−38 mol % chol and further tie lines are found at 4.5 and 7 mol % POPC. Two-component EPR spectra indicative of fluid-fluid (Lα−Lo) phase separation are found for lipid compositions: 25%<PSM<65%, 5%<chol<30–35%, 65%>POPC>10%, and confirmed by nonlinear EPR. Tie lines are identified in the Lα−Lo coexistence region, indicating that the fluid domains are of sufficient size to obey the phase rule. The three-phase triangle is bounded approximately by the compositions 40 and 75 mol % PSM with 10 mol % chol, and 60 mol % PSM with 25 mol % chol. These studies define the compositions of raft-like Lo phases for a minimal realistic biological lipid mixture

Remote consequences of polychemical and radiation therapy: cardiac valve disease complicated by infective endocarditis. Diagnostic and management problems

One of the quite frequent long-term effects of radiation therapy of malignant tumors, such as breast cancer and Hodgkin’s lymphoma primarily, when the irradiation of the mediastinum is performed, is the development of radiation-induced valvular disease. It is noted that the clinical manifestation of valve dysfunction can typically arise approximately 5 years after a course of anticancer radiotherapy. Thereafter in these patients increases the risk of infective endocarditis. However, in therapeutic and oncological clinical practice the difficulty of identifying and making the differential diagnosis of endocarditis in patients with “cancer” history is still quite common. At the moment cases of infective endocarditis after polychemotherapy and radiation therapy are not widely covered for cardiologists and internists in the medical literature. In addition before starting specific treatment due to the possible threat of infectious complications, including endocarditis, in oncology guidelines it is recommended to patients to make a thorough oral cavity sanitation, while the internists are little aware of this need, both at the stage of antitumor therapy and at late period. Today, with the increasing number of patients who are healed or achieved long-term remission after the anticancer treatment, including elderly people, it is necessary to raise the awareness among internists about occurrence options of comorbid disease in these group

Polyphenylenepyridines Based on Acetylaromatic Compounds

Nitrogen-containing polyphenylene type polymers containing pyridine rings were synthesized. The polymer-forming reaction is based on the interaction of diacetylarylene and triethylorthoformate with the formation of a pyrylium salt and subsequent treatment of the intermediate product with ammonia. The optimal ratios of the reagents for the formation of the pyridine fragment were determined. The mechanism of the main reaction is discussed. The formation of the pyridine ring and phentriyl (1,3,5-triphenylsubstituted benzene) fragments was confirmed using 1H NMR data of the example of model reactions. After heating at a temperature of 450 °C, when a more complete polycondensation process occurs, the polymers reach high values of thermal characteristics—10% weight loss in an inert atmosphere corresponds to 600 °C. The structure of the synthesized polymers was confirmed using elemental analysis, IR, XPS, and EPR spectroscopy. The conjugation length in cross-linked polyphenylene pyridines can be controlled by varying the arylene bridge groups between the phentriyl fragments, which opens up opportunities for the development of new composite materials for electrical applications

The Biological Traumatization of Crops Due to the Enzyme Stage of Enzyme-Mycotic Seed Depletion

In the light of Vavilov&rsquo;s Law, grain traumatization in the standing crop of wheat and other crops due to the enzyme stage of enzyme-mycotic seed depletion (EMSD) was confirmed, the parameters of open and hidden harmfulness were detected, and a scale of plant resistance to such traumatization was developed. The current study demonstrates that pathogen contamination in grains occurs before harvesting and its degree is determined by favorable humidity and temperature conditions and by the open and hidden grain traumatization due to the enzyme stage of EMSD, i.e., the grain&rsquo;s hydrolytic enzymes providing a growth substrate for a fungal spread that is later substituted by pathogen enzymes leading to grain spoiling and self-warming. The most common technique to preserve grain quality is to support a moisture level that prevents further spreading of the fungi. The grains that are contaminated with very low temperature and humidity levels facilitate the germinability and high quality of the grain. The new ways to withstand EMSD should, first of all, include a selection of activities. Using biological, biochemical and physical (X-ray) methods, genetic sources of resistance towards EMSD were found in the VIR world collection that is recommended for further selection. These sources have become a basis for the varieties, such as Moskovskaya 39, Ilot (winter wheat), Gremme and Gremme 2U (hulless spelt), Alcoran (winter spelt) and Kanysh (spring wheat)

Chemical Oxidative Polymerization of Methylene Blue: Reaction Mechanism and Aspects of Chain Structure

The kinetic regularities of the initial stage of chemical oxidative polymerization of methylene blue under the action of ammonium peroxodisulfate in an aqueous medium have been established by the method of potentiometry. It was shown that the methylene blue polymerization mechanism includes the stages of chain initiation and growth. It was found that the rate of the initial stage of the reaction obeys the kinetic equation of the first order with the activation energy 49 kJ · mol−1. Based on the proposed mechanism of oxidative polymerization of methylene blue and the data of MALDI, EPR, and IR spectroscopy methods, the structure of the polymethylene blue chain is proposed. It has been shown that polymethylene blue has a metallic luster, and its electrical conductivity is probably the result of conjugation over extended chain sections and the formation of charge transfer complexes. It was found that polymethylene blue is resistant to heating up to a temperature of 440 K and then enters into exothermic transformations without significant weight loss. When the temperature rises above 480 K, polymethylene blue is subject to endothermic degradation and retains 75% of its mass up to 1000 K