Sulfated Phenolic Substances: Preparation and Optimized HPLC Analysis

Sulfation is an important reaction in nature, and sulfated phenolic compounds are of interest as standards of mammalian phase II metabolites or pro-drugs. Such standards can be prepared using chemoenzymatic methods with aryl sulfotransferases. The aim of the present work was to obtain a large library of sulfated phenols, phenolic acids, flavonoids, and flavonolignans and optimize their HPLC (high performance liquid chromatography) analysis. Four new sulfates of 2,3,4-trihydroxybenzoic acid, catechol, 4-methylcatechol, and phloroglucinol were prepared and fully characterized using MS (mass spectrometry), ¹H, and ¹³C NMR. The separation was investigated using HPLC with PDA (photodiode-array) detection and a total of 38 standards of phenolics and their sulfates. Different stationary (monolithic C18, C18 Polar, pentafluorophenyl, ZICpHILIC) and mobile phases with or without ammonium acetate buffer were compared. The separation results were strongly dependent on the pH and buffer capacity of the mobile phase. The developed robust HPLC method is suitable for the separation of enzymatic sulfation reaction mixtures of flavonoids, flavonolignans, 2,3-dehydroflavonolignans, phenolic acids, and phenols with PDA detection. Moreover, the method is directly applicable in conjunction with mass detection due to the low flow rate and the absence of phosphate buffer and/or ion-pairing reagents in the mobile phase.     

Lipid Nanoparticles for Broad-Spectrum Nucleic Acid Delivery

Lipid nanoparticles (LNPs) are the most advanced nonviral modality for nucleic acid (NA) delivery, and have recently gained enormous attention in the fields of RNA therapeutics and vaccine development. Here, ionizable adamantane-based lipidoids named XMaNs, which circumvent the usual need for laborious optimization of LNP components for highly diverse types of NAs, are described. The non-toxic XMaN6 lipidoid is highly versatile in entrapment and delivery of siRNA, mRNA, plasmid DNA, and a cyclic dinucleotide. XMaN6-based LNPs efficiently deliver: 1) siRNA into human primary hepatocytes and cell lines that are hard-to-transfect; 2) mRNA into mouse liver; 3) plasmid DNA; 4) 2′,3′-cGAMP into cells and activated the cGAS-STING pathway three orders of magnitude more efficiently than 2′,3′-cGAMP alone. To our knowledge, such universality in delivering different NA types has not been previously described and can accelerate translation of LNPs into the clinic.     

Dual‐Action Flexible Antimicrobial Material: Switchable Self‐Cleaning,Antifouling, and Smart Drug Release

A switchable material with a smart antimicrobial dual‐action functionality, which is based on a highly stretchable silicon polymer gradiently doped with polyyrrole, is proposed. The material exhibits superhydrophobic and self‐cleaning properties, high aerophilicity as well as the possibility of smart, electrically triggerable release of an incorporated drug. During the immersion of the material in water, an air gap is formed on its surface which prevents a formation of biofouling, attachment of microorganisms, and burst release of the incorporated drug. An application of external electric field switches the surface properties from the superhydrophobic to highly hydrophilic state that enables a wetting of the material surface and electrically triggered release of a loaded drug. After the electric field switching off and sample drying, the material surface returns to its intrinsic superhydrophobic state with the original self‐cleaning properties so that the material surface can be simply cleaned, removing the bacteria. High flexibility and stretchability are additional favorable properties of the proposed smart antimicrobial material, making it a suitable candidate for a range of medical and related applications.     

Identification of Nrl1 Domains Responsible for Interactions with RNA-Processing Factors and Regulation of Nrl1 Function by Phosphorylation

Pre-mRNA splicing is a key process in the regulation of gene expression. In the fission yeast Schizosaccharomyces pombe, Nrl1 regulates splicing and expression of several genes and non-coding RNAs, and also suppresses the accumulation of R-loops. Here, we report analysis of interactions between Nrl1 and selected RNA-processing proteins and regulation of Nrl1 function by phosphorylation. Bacterial two-hybrid system (BACTH) assays revealed that the N-terminal region of Nrl1 is important for the interaction with ATP-dependent RNA helicase Mtl1 while the C-terminal region of Nrl1 is important for interactions with spliceosome components Ctr1, Ntr2, and Syf3. Consistent with this result, tandem affinity purification showed that Mtl1, but not Ctr1, Ntr2, or Syf3, co-purifies with the N-terminal region of Nrl1. Interestingly, mass-spectrometry analysis revealed that in addition to previously identified phosphorylation sites, Nrl1 is also phosphorylated on serines 86 and 112, and that Nrl1-TAP co-purifies with Cka1, the catalytic subunit of casein kinase 2. In vitro assay showed that Cka1 can phosphorylate bacterially expressed Nrl1 fragments. An analysis of non-phosphorylatable nrl1 mutants revealed defects in gene expression and splicing consistent with the notion that phosphorylation is an important regulator of Nrl1 function. Taken together, our results provide insights into two mechanisms that are involved in the regulation of the spliceosome-associated factor Nrl1, namely domain-specific interactions between Nrl1 and RNA-processing proteins and post-translational modification of Nrl1 by phosphorylation.     

Thiourea and Guanidine Compounds and Their Iridium Complexes in Drug-Resistant Cancer Cell Lines: Structure-Activity Relationships and Direct Luminescent Imaging

Thiourea and guanidine units are found in nature, medicine, and materials. Their continued exploration in applications as diverse as cancer therapy, sensors, and electronics means that their toxicity is an important consideration. Iridium complexes present new opportunities for drug development and imaging in terms of structure and photoactivity. We have systematically synthesised a set of thiourea and guanidine compounds and iridium complexes thereof, and elucidated structure–activity relationships for cellular toxicity in three ovarian cancer cell lines and their cisplatin-resistant sub-lines. We have been able to use the intrinsic luminescence of iridium complexes to visualise the effect of both structure alteration and cellular resistance mechanisms. These findings provide starting points for the development of new drugs and consideration of safety issues for novel thiourea-, guanidine-, and iridium-based materials.     

Survival of three Mycobacterium avium subsp. hominissuis isolates in fish products after hot smoking and frying

Fish mycobacteriosis should be considered as one possible means of transmission of mycobacterial infections to humans. In our study, we examined the survival of three field Mycobacterium avium subsp. hominissuis (MAH) isolates in fish meat during thermal processing technologies using culture and quantitative real‐time PCR (qPCR) methods. Minced carp meat mixture was artificially contaminated with known amount of MAH cells and survival and absolute numbers of MAH was monitored after hot smoking and frying. The viability of MAH was significantly lower after the frying process, whereas in response to hot smoking viable MAH cells could still be cultured even after 10 min at 70 °C. Significant differences in thermal stability were also observed among the three different MAH isolates. The human isolate was the most resistant, whereas the environmental isolate was the least resistant, which is probably due to host adaptability. In this work we confirmed that MAH can survive temperatures of 70 °C and thus can pose a risk to consumers.     

Fluorescent probing of membrane potential in walled cells: diS-C3(3) assay in Saccharomyces cerevisiae

Membrane-potential-dependent accumulation of diS-C₃(3) in intact yeast cells in suspension is accompanied by a red shift of the maximum of its fluorescence emission spectrum, λ_max, caused by a readily reversible probe binding to cell constituents. Membrane depolarization by external KCl (with or without valinomycin) or by ionophores causes a fast and reproducible blue shift. As the potential-reporting parameter, the λ_max shift is less affected by probe binding to cuvette walls and possible photobleaching than, for example, fluorescence intensity. The magnitude of the potential-dependent red λ_max shift depends on relative cell-to-probe concentration ratio, a maximum shift (572→582 nm) being found in very thick suspensions and in cell lysates. The potential therefore has to be assessed at reasonably low cell (≤5×10⁶ cells/ml) and probe (10⁻⁷ M) concentrations at which a clearly defined relationship exists between the λ_max shift and the potential-dependent accumulation of the dye in the cells. The redistribution of the probe between the medium and yeast protoplasts takes about 5 min, but in intact cells it takes 10–30 min because the cell wall acts as a barrier, hampering probe penetration into the cells. The barrier properties of the cell wall correlate with its thickness: cells grown in 0·2% glucose (cell wall thickness 0·175±0·015 μm, n=30) are stained much faster and the λ_max is more red-shifted than in cells grown in 2% glucose (cell wall thickness 0·260±0·043 μm, n=44). At a suitable cell and probe concentration and under standard conditions, the λ_max shift of diS-C₃(3) fluorescence provides reliable information on even fast changes in membrane potential in Saccharomyces cerevisiae. © 1998 John Wiley & Sons, Ltd.     

Effect of plasma sizing on basalt fibers adhesion with wood-working resins

European Journal of Wood and Wood Products - Basalt fabric with manufacturer-made silane sizing was additionally treated by propane-butane enriched atmospheric pressure nitrogen plasma for 15 and...     

Export of arsenic from forested catchments under easing atmospheric pollution

Massive lignite burning in Central European power plants peaked in the 1980s. Dissolved arsenic in runoff from upland forest ecosystems is one of the ecotoxicological risks resulting from power plant emissions. Maxima in As concentrations in runoff from four forest catchments have increased 2-5 times between 1995 and 2006, and approach the drinking water limit (10 microg L(-1)). To assess the fate of anthropogenic As, we constructed input/output mass balances for three polluted and one relatively unpolluted forest catchment in the Czech Republic, and evaluated the pool size of soil As. The observation period was 11 years, and the sites spanned a 6-fold As pollution gradient. Two of the polluted sites exhibit large net As export via runoff solutes (mean of 4-5 g As ha(-1) yr(-1) for the 11-year period; up to 28 g As ha(-1) yr(-1) in 2005). This contrasts with previous studies which concluded that forest catchments are a net sink for atmogenic arsenic both at times of increasing and decreasing pollution. The amount of exported As is not correlated with the total As soil pool size, which is over 78% geogenic in origin, but correlates closely with water fluxes via runoff. Net arsenic release is caused by an interplay of hydrological conditions and retreating acidification which may mobilize arsenic by competitive ligand exchange. The effects of droughts and other aspects of climate change on subsequent As release from soil were not investigated. Between-site comparisons indicate that most pollutant As may be released from humus.