Microstructure study of poly(isobutyl acrylate) and poly(<Emphasis Type="Italic">sec</Emphasis>-butyl acrylate) by incremental analysis of <Superscript>13</Superscript>C NMR spectra

Microstructure of poly(isobutyl acrylate) (PiBuA) and poly(sec-butyl acrylate) (PsBuA), prepared by free radical and anionic polymerization, was investigated by ¹³C NMR spectroscopy. The carbonyl signal in the 100 MHz ¹³C NMR spectra of both homopolymers provided sufficient resolution to perform detailed analysis of distribution of configurational sequences at the pentad/heptad level. Application of Bernoulli and first order Markov statistics to determine probabilities of configurational sequences and incremental calculation to estimate chemical shifts of the individual sequences allowed for positive simulation of carbonyl signals.     

Surface and interfacial fourier transform infrared spectroscopic studies of latexes. XIV. Surface phase separation in polystyrene/poly-n-butyl acrylate latex films

This study focuses on the behavior of sodium dioctylsulfosuccinate (SDOSS) in 50/50 w/w % polystyrene/poly(butyl acrylate) (p-Sty/p-BA) latex films. Specifically, mobility and orientation are examined in the context of the film formation by the use of dynamic mechanical thermal analysis and attenuated total reflectance (ATR) Fourier transform infrared (FT-IR) spectroscopy. While for the homopolymer blends of p-Sty and p-BA, two T_g values resulting from a phase separation of p-Sty and p-BA phases are observed, only a single T_g is detected for a copolymer of the same mixture, indicating a single phase within the film. ATR FTIR spectroscopic data indicate that the phase separation of p-Sty and p-BA blends does not occur uniformly across the film. After coalescence, p-Sty particles produce a significant degree of stratification at approximately 1.6 μm from the film surface. At this depth, the polystyrene rings assume preferentially parallel orientation to the film surface. At the same time, the hydrophilic groups of SDOSS surfactant (SO⁻₃Na⁺) are oriented preferentiallyparallel to the surface. Under high relative humidity conditions, water is able to diffuse into the film and swells the surface layers, thus causing them to expand. As a result, the top, predominately poly-n-BA surface becomes “thicker», and p-Sty phase appears to be near 2.3 μm from the surface. The polystyrene rings maintain their preferential parallel orientation to the surface, but the hydrophilic groups of SDOSS are able to diffuse into the film with the water uptake and are thus not present at the filmair interface. © 1996 John Wiley & Sons, Inc.     

Extracellular Nucleotides Affect the Proangiogenic Behavior of Fibroblasts,Keratinocytes, and Endothelial Cells

Chronic wound healing is currently a severe problem due to its incidence and associated complications. Intensive research is underway on substances that retain their biological activity in the wound microenvironment and stimulate the formation of new blood vessels critical for tissue regeneration. This group includes synthetic compounds with proangiogenic activity. Previously, we identified phosphorothioate analogs of nucleoside 5′-O-monophosphates as multifunctional ligands of P2Y6 and P2Y14 receptors. The effects of a series of unmodified and phosphorothioate nucleotide analogs on the secretion of VEGF from keratinocytes and fibroblasts, as well as their influence on the viability and proliferation of keratinocytes, fibroblasts, and endothelial cells were analyzed. In addition, the expression profiles of genes encoding nucleotide receptors in tested cell models were also investigated. In this study, we defined thymidine 5′-O-monophosphorothioate (TMPS) as a positive regulator of angiogenesis. Preliminary analyses confirmed the proangiogenic potency of TMPS in vivo.     

Cytokine Receptors—Regulators of Antimycobacterial Immune Response

Cytokine receptors are critical regulators of the antimycobacterial immune response, playing a key role in initiating and coordinating the recruitment and activation of immune cells during infection. They recognize and bind specific cytokines and are involved in inducing intracellular signal transduction pathways that regulate a diverse range of biological functions, including proliferation, differentiation, metabolism and cell growth. Due to mutations in cytokine receptor genes, defective signaling may contribute to increased susceptibility to mycobacteria, allowing the pathogens to avoid killing and immune surveillance. This paper provides an overview of cytokine receptors important for the innate and adaptive immune responses against mycobacteria and discusses the implications of receptor gene defects for the course of mycobacterial infection.     

Catalytic Sulfation of Betulin with Sulfamic Acid: Experiment and DFT Calculation

Betulin is an important triterpenoid substance isolated from birch bark, which, together with its sulfates, exhibits important bioactive properties. We report on a newly developed method of betulin sulfation with sulfamic acid in pyridine in the presence of an Amberlyst^®15 solid acid catalyst. It has been shown that this catalyst remains stable when being repeatedly (up to four cycles) used and ensures obtaining of sulfated betulin with a sulfur content of ~10%. The introduction of the sulfate group into the betulin molecule has been proven by Fourier-transform infrared, ultraviolet-visible, and nuclear magnetic resonance spectroscopy. The Fourier-transform infrared (FTIR) spectra contain absorption bands at 1249 and 835–841 cm⁻¹; in the UV spectra, the peak intensity decreases; and, in the nuclear magnetic resonance (NMR) spectra, of betulin disulfate, carbons С3 and С28 are completely shifted to the weak-field region (to 88.21 and 67.32 ppm, respectively) with respect to betulin. Using the potentiometric titration method, the product of acidity constants K₁ and K₂ of a solution of the betulin disulfate H⁺ form has been found to be 3.86 × 10^–6 ± 0.004. It has been demonstrated by the thermal analysis that betulin and the betulin disulfate sodium salt are stable at temperatures of up to 240 and 220 °C, respectively. The density functional theory method has been used to obtain data on the most stable conformations, molecular electrostatic potential, frontier molecular orbitals, and mulliken atomic charges of betulin and betulin disulfate and to calculate the spectral characteristics of initial and sulfated betulin, which agree well with the experimental data.     

Curcumin and Weight Loss: Does It Work?

Obesity is a global health problem needing urgent research. Synthetic anti-obesity drugs show side effects and variable effectiveness. Thus, there is a tendency to use natural compounds for the management of obesity. There is a considerable body of knowledge, supported by rigorous experimental data, that natural polyphenols, including curcumin, can be an effective and safer alternative for managing obesity. Curcumin is a is an important compound present in Curcuma longa L. rhizome. It is a lipophilic molecule that rapidly permeates cell membrane. Curcumin has been used as a pharmacological traditional medicinal agent in Ayurvedic medicine for ∼6000 years. This plant metabolite doubtless effectiveness has been reported through increasingly detailed in vitro, in vivo and clinical trials. Regarding its biological effects, multiple health-promoting, disease-preventing and even treatment attributes have been remarkably highlighted. This review documents the status of research on anti-obesity mechanisms and evaluates the effectiveness of curcumin for management of obesity. It summarizes different mechanisms of anti-obesity action, associated with the enzymes, energy expenditure, adipocyte differentiation, lipid metabolism, gut microbiota and anti-inflammatory potential of curcumin. However, there is still a need for systematic and targeted clinical studies before curcumin can be used as the mainstream therapy for managing obesity.     

Relaxation dynamics of excited states of Tm3+ ions in TeO2-ZnO-Na2O-Y2O3 glasses

Tellurite glasses with the composition of xTm_2O_3-(6-x)Y_2O_3-3Na_2O-25ZnO-66TeO_2(where 0≤x≤6)were obtained by the melt-quenching technique.Absorption(300 K),excitation(300 K) and fluorescence spectra(300 K) as well as fluorescence decay curves of Tm~(3+)-doped title glasses are presented and discussed in details.The Judd-Ofelt analysis based on the room temperature absorption spectrum was applied for determination of fundamental fluorescence properties such as radiative transition probabilities(A_T),branching ratios(β_R),radiative lifetimes(τ_R) of the emitting levels of the Tm~(3+) ion and stimulated emission cross-sections(σ_(em)).Fluorescence spectra were recorded and analysed in the visible and near-infrared spectral range.The emission and effective cross-section were calculated for the ~3F_4→~3H_6 transition,showing that the investigated glasses are promising laser host materials,operating at 1.8 μm.The observed concentration quenching and non-exponential decay curves from the ~1 G_4 and ~3H_4 states indicate nonradiative energy transfer between Tm~(3+) ions.The analysis of non-exponential fluorescence decay curves from the ~1 G_4 and ~3H_4 levels was carried out in framework of the InokutiHirayama and Yokota-Tanimoto models and energy transfer microparameters were determined.The self-quenching model was proposed for describing relaxation of the first excited state of the Tm~(3+) ion.     

Investigating the Potential Use of Chemical Biopsy Devices to Characterize Brain Tumor Lipidomes

The development of a fast and accurate intraoperative method that enables the differentiation and stratification of cancerous lesions is still a challenging problem in laboratory medicine. Therefore, it is important to find and optimize a simple and effective analytical method of enabling the selection of distinctive metabolites. This study aims to assess the usefulness of solid-phase microextraction (SPME) probes as a sampling method for the lipidomic analysis of brain tumors. To this end, SPME was applied to sample brain tumors immediately after excision, followed by lipidomic analysis via liquid chromatography-high resolution mass spectrometry (LC-HRMS). The results showed that long fibers were a good option for extracting analytes from an entire lesion to obtain an average lipidomic profile. Moreover, significant differences between tumors of different histological origin were observed. In-depth investigation of the glioma samples revealed that malignancy grade and isocitrate dehydrogenase (IDH) mutation status impact the lipidomic composition of the tumor, whereas 1p/19q co-deletion did not appear to alter the lipid profile. This first on-site lipidomic analysis of intact tumors proved that chemical biopsy with SPME is a promising tool for the simple and fast extraction of lipid markers in neurooncology.     

Chemical composition of the cell wall of probiotic and brewer’s yeast in response to cultivation medium with glycerol as a carbon source

The structure of cell wall of yeasts (genus Saccharomyces) is one of the factors that determine their health-promoting properties connected to the presence of β-glucans and mannoprotein. The aim of the study was to determine the influence of glycerol as a carbon source on structural polymers of cell wall (β-glucan and mannoprotein) of probiotic yeasts Saccharomyces cerevisiae var. boulardii and brewer’s yeasts S. cerevisiae R9. Significant increase of the percentage of polysaccharide content in the cell wall dry weight of S. cerevisiae R9 brewer’s yeasts was noted (in the range of 10–20 %) after cultivation in medium containing glycerol at a concentration of 2–5 % and pH 4.0. The highest content of carbohydrates in probiotic yeasts’ cell wall (58 %) was observed after cultivation in medium containing 3 % of glycerol and pH 5.0. The cell wall of probiotic yeasts was characterized by higher content of mannoprotein comparing with cell wall preparation of brewer’s yeasts S. cerevisiae R9 composed mainly of β-glucans. After cultivation in mediums with 2 and 3 % of glycerol, the cell of brewer’s yeasts contained the highest amount of β(1,3/1,6)-glucan in dry weight of the cell wall (about 36 %). Glycerol at a concentration of 3 and 5 % also intensified mannoprotein biosynthesis in cell wall of S. cerevisiae R9, approximating their content to those noted in the cells of probiotic yeasts (about 29 % (w/w) of dry weight of the cell wall) after cultivation in a medium of pH 5.0 containing 3 % of glycerol.