Interactions of phospholipase D with 1,2 diacyl-sn-glycerol-3-phosphorylcholine,dodecylsulfate, and Ca2+

Some properties of the pure, soluble phospholipase D (phosphatidycholine phosphatido hydrolase, EC 3.1.4.4) interactions with phosphatidyl choline (1,2 diacyl-sn-glycerol-3-phosphoryl choline) in a system also containing dodecylsulfate and Ca²⁺ ions were studied. Concentrations of Ca²⁺ greater than 50 mM were necessary both for activity and adsorption of the enzyme to the “supersubstrate.” Ethylenediamine tetraacetic acid caused inhibition of activity, greater than one would expect from its chelating capacity. A nonlinear increase in activity with the increase of enzyme protein was observed, suggesting a subunit aggregation into a higher mol wt protein, catalytically more active. Upon centrifugation of the supersubstrate-enzyme complex at 4.5×10⁵ g·min at 30 C, most of the substrate molecules sedimented regardless of the pH. The reverse was true when centrifugation was done at 1 C. Phospholipase D hydrolyzed phosphatidylcholine molecules present in the supersubstrate at temperatures around 0 C at a rate 1/5 that of a maximal value measured at 30C. The Arrhenius plot was linear in the range from 0 to 30 C, and at that temperature the curve broke with a smaller slope. Activation energy of 9.1 Kcal/mol, below 30 C, was calculated. Adsorption of the enzyme to the sedimentable supersubstrate occurred at pH 8.0, regardless of temperature. At pH 5.6, a considerable portion of phosphatidylcholine was degraded at 30 C, thus minimizing the capacity of the supersubstrate to adsorb the enzyme. Although Mg²⁺ could replace Ca²⁺ in the formation of sedimentable supersubstrate, it neither assists in adsorption of the enzyme nor in activation of the phosphatidylcholine hydrolysis.     

The Role of CXCL16 in the Pathogenesis of Cancer and Other Diseases

CXCL16 is a chemotactic cytokine belonging to the α-chemokine subfamily. It plays a significant role in the progression of cancer, as well as the course of atherosclerosis, renal fibrosis, and non-alcoholic fatty liver disease (NAFLD). Since there has been no review paper discussing the importance of this chemokine in various diseases, we have collected all available knowledge about CXCL16 in this review. In the first part of the paper, we discuss background information about CXCL16 and its receptor, CXCR6. Next, we focus on the importance of CXCL16 in a variety of diseases, with an emphasis on cancer. We discuss the role of CXCL16 in tumor cell proliferation, migration, invasion, and metastasis. Next, we describe the role of CXCL16 in the tumor microenvironment, including involvement in angiogenesis, and its significance in tumor-associated cells (cancer associated fibroblasts (CAF), microglia, tumor-associated macrophages (TAM), tumor-associated neutrophils (TAN), mesenchymal stem cells (MSC), myeloid suppressor cells (MDSC), and regulatory T cells (T_reg)). Finally, we focus on the antitumor properties of CXCL16, which are mainly caused by natural killer T (NKT) cells. At the end of the article, we summarize the importance of CXCL16 in cancer therapy.     

Model of Environmental Membrane Field for Transmembrane Proteins

The water environment determines the activity of biological processes. The role of such an environment interpreted in the form of an external field expressed by the 3D Gaussian distribution in the fuzzy oil drop model directs the folding process towards the generation of a centrally located hydrophobic core with the simultaneous exposure of polar residues on the surface. In addition to proteins soluble in the water environment, there is a significant group of membrane proteins that act as receptors or channels, including ion channels in particular. The change of the polar (water) environment into a highly hydrophobic (membrane) environment is quite radical, resulting in a different hydrophobicity distribution within the membrane protein. Modification of the notation of the force field expressing the presence of the hydrophobic environment has been proposed in this work. A modified fuzzy oil drop model with its adaptation to membrane proteins was used to interpret the structure of membrane proteins–mechanosensitive channel. The modified model was also used to describe the so-called negative cases—i.e., for water-soluble proteins with a clear distribution consistent with the fuzzy oil drop model.     

Scent Marking in Male Premating Behavior of Bombus confusus

Premating behavior in the species Bombus confusus Schenck, 1859 was studied. The marking habits of bumblebee males were revealed and the use of their labial gland secretion in scent marks was proved chemically. Identical compounds were present both in the labial gland secretion and on male-marked objects. This chemical proof is reported for the first time from natural conditions of a B. confusus locality. Males' flight activities, site tenacity, and male–male interactions are described in detail. Contrary to literature reports, male B. confusus behavior does not basically differ from that of already known perching bumblebee species.     

Unusual Fatty Acids in the Fat Body of the Early Nesting Bumblebee, <Emphasis Type="Italic">Bombus pratorum</Emphasis>

Unusual fatty acids with 24, 26, and 28 carbon atoms were found in triacylglycerols (TAGs) isolated from fat body tissue of bumblebee Bombus pratorum. The most abundant one was (Z,Z)-9,19-hexacosadienoic acid. Its structure was determined by mass spectrometry after derivatization with dimethyl disulfide and by infrared spectroscopy. ECL (equivalent chain length) values of its methyl ester were determined on both DB-1 and DB-WAX capillary columns. (Z,Z)-9,19-Hexacosadienoic acid is quite rare in nature. So far it has been identified only in marine sponges, and this work is the first evidence of its occurrence in a terrestrial organism. HPLC/MS analysis of the bumblebee TAGs showed that (Z,Z)-9,19-hexacosadienoic acid is present in one third of all TAG molecular species. As it was found in all sn-TAG positions, it is likely that (Z,Z)-9,19-hexacosadienoic acid is transported to tissues. Interestingly, labial gland secretion of B. pratorum was found to contain (Z,Z)-7,17-pentacosadiene, a hydrocarbon with markedly similar double bond positions and geometry. Possible biosynthetic relationships between these two compounds are discussed.     

Solvothermal synthesis of a novel mixed valence Cu(I)/Cu(II) complex containing sulphate, malate and 4,4-bipyridine, [CuCu2(mal)(SO4)(bpy)2 · H2O]n. Unique binding mode of the malate anion

The reaction of CuSO₄ · 5H₂O with 4,4^′-bipyridine and malic acid at 140 °C under solvothermal conditions afforded a mixed valence three-dimensional coordination polymer [Cu^ICu^II₂(mal)(SO₄)(bpy)₂ · H₂O]_n, (1). The building unit consists of a Cu²⁺-dimer in which copper centers are bridged by malate and sulphate anions. SO₄²⁻ anion further connects dimeric unit with the Cu¹⁺ center. Building units are linked by 4,4^′-bipyridine ligands to form double chains, that are interconnected into 3D network through additional sulphate bridge.     

(S)-(+)-linalool,a mate attractant pheromone component in the bee Colletes cunicularius

Enantiomerically pure (S)-(+)-linalool was the main constituent in the extracts of the cephalic secretions of virgin females, mated females, freshly emerged males, and patrolling males of the solitary bee Colletes cunicularius. After copulation, the content of (S)-(+)-linalool emitted by the female was strongly reduced. Electrophysiological experiments revealed that both enantiomers of linalool elicited responses from the antennae of the males. Field tests using the pure enantiomers and the racemate of linalool showed that the number of male bees attracted was highest for (S)-(+)-linalool. The search flight activity in the mating flight area increased dramatically when patrolling males were presented with (S)-(+)-linalool vs (R)-(–)-linalool. Taken together, these data indicate a mate attractant pheromone function of (S)-(+)-linalool.     

Protective properties of SiO2 with SiO2 and Al2O3 nanoparticles sol-gel coatings deposited on FeCrAl alloys

Five layer SiO₂ coatings containing SiO₂ or Al₂O₃ nanopowders were deposited on FeCrAl alloy support by sol-gel method. Studies of protective properties of the coatings were carried out during high temperature cyclic oxidation. Changes in surface topography, structure and chemical composition of the surface layer of FeCrAl alloy were investigated. It has been shown that the type of nanofillers present in the SiO₂ coating (about 2.5?wt%) affects morphology of Al₂O₃ growing scale and determines the heat resistance of FeCrAl alloy. The lowest relative mass change (approx. 1.3%) after 10 oxidation cycles in air at 900?°C (one cycle = 12?h) was measured for the samples with coatings containing hydrophilic nanosilica (Aerosil 380) as filler. The protective efficiency of the coatings in the process of high-temperature oxidation is from 66% to 85%. The thickness of the formed scale and the value of the parabolic rate constant depend on the type of nanopowder in the coating.     

Biocompatible surface modification of poly(ethylene terephthalate) focused on pathogenic bacteria: Promising prospects in biomedical applications

Poly(ethylene terephthalate)—PET, is one of the most common polyesters, widely used in biomedical applications ranging from catheters to stents, vascular grafts, heart valves, sutures, and scaffolds. PET surface modification is necessary to impart desired properties for biomedical applications, making the polymer biocompatible, noncytotoxic and antibacterial that can preferably resist biofilm formation caused by pathogenic bacteria. A novel approach to anticorrosive wet chemical surface modification of PET by insertion of alkyl and hydroxyl groups was achieved by using Grignard reagents and confirmed by several different characterization methods including Fourier transform infrared spectroscopy (FTIR), water contact angle (WCA) measurement, free surface energy (FSE) measurement, scanning electron microscopy (SEM), and atomic force microscopy (AFM). High antibacterial efficiency against four different types of biofilm active, pathogenic bacterial strains namely: Staphylococcus aureus, Escherichia coli, methicillin‐resistant S. aureus (MRSA), and Pseudomonas aeruginosa was established on the modified PET surface. Biocompatibility higher than 84% of the modified samples has been proved. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44990.     

Adsorption of hydrophilic and hydrophobic pharmaceuticals on RO/NF membranes: Identification of interactions using FTIR

This article examines the adsorption of pharmaceuticals on reverse osmosis (RO) and nanofiltration (NF) membranes. The membranes were characterized in terms of Fourier transformation infrared (FTIR) spectra, surface charge, hydrophobicity, pore size distribution, and roughness. Five pharmaceuticals were used to determine their rejection and possible interactions with the membranes. Albendazole, a hydrophobic pharmaceutical, adsorbed on the NF (NF270) and RO (XLE) membranes. FTIR spectra showed significant changes (new peaks/bonds) on the membranes, confirming that adsorption plays an important role in the overall mechanism of rejection in the case of hydrophobic compounds. Hydrophilic pharmaceuticals (sulfaguanidine, trimethoprim, hydrocortisone, and procaine) did not adsorb on the XLE membrane, showing that size exclusion and electrostatic repulsion were both dominant removal mechanisms. This article gives new insights into NF membranes in the treatment of hydrophilic compounds. The results clearly show the adsorption of hydrophilic compounds on the NF membranes since H‐bonds and π–π interactions were observed on their FTIR spectra. Therefore, both the hydrophobic and the hydrophilic adsorption have to be taken into account when considering the removal mechanism, especially in the case of NF membranes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44426.