MPP1-based mechanism of resting state raft organization in the plasma membrane. Is it a general or specialized mechanism in erythroid cells?

Biological membranes are organized in various microdomains, one of the best known being called membrane rafts. The major function of these is thought to organize signaling partners into functional complexes. An important protein found in membrane raft microdomains of erythroid and other blood cells is MPP1 (membrane palmitoylated protein 1)/p55. MPP1 (p55) belongs to the MAGUK (membrane-associated guanylate kinase homolog) family and it is a major target of palmitoylation in the red blood cells (RBCs) membrane. The well-known function of this protein is to participate in formation of the junctional complex of the erythrocyte mem­brane skeleton. However, its function as a “raft organizer” is not well understood. In this review we focus on recent reports concerning MPP1 participation in membrane rafts organization in erythroid cells, including its role in signal transduction. Currently it is not known whether MPP1 could have a similar role in cell types other than erythroid lineage. We present also preliminary data regarding the expression level of MPP1 gene in several non-erythroid cell lines

Successful outcome of phytostabilization in Cr(VI) contaminated soils amended with alkalizing additives

This study analysed the effect of three alkalizing soil amendments (limestone, dolomite chalcedonite) on aided phytostabilization with Festuca rubra L. depending on the hexavalent chromium (Cr(VI)) level in contaminated soil. Four different levels of Cr(VI) were added to the soil (0, 50, 100 and 150 mg/kg). The Cr contents in the plant roots and above-ground parts and the soil (total and extracted Cr by 0.01 M CaCl2) were determined with flame atomic absorption spectrometry. The phytotoxicity of the soil was also determined. Soil amended with chalcedonite significantly increased F. rubra biomass. Chalcedonite and limestone favored a considerable accumulation of Cr in the roots. The application of dolomite and limestone to soil contaminated with Cr(VI) contributed to a significant increase in pH values and was found to be the most effective in reducing total Cr and CaCl2-extracted Cr contents from the soil. F. rubra in combination with a chalcedonite amendment appears to be a promising solution for phytostabilization of Cr(VI)-contaminated areas. The use of this model can contribute to reducing human exposure to Cr(VI) and its associated health risks. © 2020 by the authors.Ministerstwo Nauki i Szkolnictwa Wyższego: MNiS

5-Deazaalloxazine as photosensitizer of singlet oxygen and potential redox-sensitive agent

Flavins are a unique class of compounds that combine the features of singlet oxygen generators and redox-dependent fluorophores. From a broad family of flavin derivatives, deazaalloxazines are significantly underdeveloped from the point of view of photophysical properties. Herein, we report photophysics of 5-deazaalloxazine (1a) in water, acetonitrile, and some other solvents. In particular, triplet excited states of 1ain water and in acetonitrile were investigated using ultraviolet-visible (UV-Vis) transient absorption spectroscopy. The measured triplet lifetimes for 1a were all on the microsecond time scale (approximate to 60 mu s) in deoxygenated solutions. The quantum yield of S-1 -> T-1 intersystem crossing for 1ain water was 0.43 based on T1 energy transfer from 1a to indicaxanthin (5) acting as acceptor and on comparative actinometric measurements using benzophenone (6). 1a was an efficient photosensitizer for singlet oxygen in aerated solutions, with quantum yields of singlet oxygen in methanol of about 0.76, compared to acetonitrile similar to 0.74, dichloromethane similar to 0.64 and 1,2-dichloroethane similar to 0.54. Significantly lower singlet oxygen quantum yields were obtained in water and deuterated water (Phi(Delta)similar to 0.42 and 0.44, respectively). Human red blood cells (RBC) were used as a cell model to study the antioxidant capacity in vitro and cytotoxic activity of 1a. Fluorescence-lifetime imaging microscopy (FLIM) data were analyzed by fluorescence lifetime parameters and distribution for different parts of the emission spectrum. Comparison of multidimensional fluorescent properties of RBC under physiological-like and oxidative-stress conditions in the presence and absence of 1a suggests its dual activity as probe and singlet-oxygen generator and opens up a pathway for using FLIM to analyze complex intracellular behavior of flavin-like compounds. These new data on structure-property relationship contribute to the body of information required for a rational design of flavin-based tools for future biological and biochemical applications.National Science Centre, Poland 2017/27/B/ST4/02494 (OPUS), NCN CEUS-UNISONO 2020/02/Y/ST4/00042, 2018/29/B/ST4/01498 (Opus), POIR.04.04.00-00-441F/17-00, Grant Agency of the Czech Republic 2013/08/T/ST4/00640 (Etiuda), Foundation for Polish Science 21-14200K, Smart Growth Operational Programme 2014-2020 POIR.04.02.00-00-C004/19-00, Ministry of Science and Higher Education, Poland DIR/WK/2018/06info:eu-repo/semantics/publishedVersio

The Impact of Supply Voltage Waveform Distortion on Non-Intentional Emission in the Frequency Range 2–150 kHz: An Experimental Study with Power-Line Communication and Selected End-User Equipment

Knowledge of the conducted emissions in the frequency range 2–150 kHz contains some gaps related to the impact of the harmonics in the supply voltage on the nature of these emissions. It can be noticed that the conducted emissions from non-sinusoidal power supplies have not been studied sufficiently, and that the impact of this distortion may be greater than the generally known results of emission tests carried out under standardized test conditions. This paper is aimed at investigating experimental cases of the influence of supply voltage waveform distortion on non-intentional emission in the range 2–150 kHz and the efficiency of power line communication based on selected PRIME (PoweRline Intelligent Metering Evolution) power line communication (PLC) technology. A series of experimental laboratory studies were investigated, representing the operation of the investigated PLC system with different types of end-user equipment (LED—Light Emitting Diode, CFL—Compact Fluorescent Lamp, induction motor with frequency converter) working under a distorted supply voltage condition obtained by the programmable power supply for different scenarios of the admissible harmonics contribution in the range 0–2 kHz. The scenarios included limits defined in standards EN 50160 and IEC 61000-4-13. The researchers used spectral analysis with a notation to emission limits, compatibility levels, and mains signalling, as well as statistics of the PLC communication. The obtained results provide important conclusions, which may be applied both in the development of the design of the appliances in question and the higher frequency emission testing methods

Novel N7-Arylmethyl Substituted Dinucleotide mRNA 5′ cap Analogs: Synthesis and Evaluation as Modulators of Translation

Dinucleotide analogs of the messenger RNA cap (m7GpppN) are useful research tools and have potential applications as translational inhibitors or reagents for modification of in vitro transcribed mRNAs. It has been previously reported that replacing the methyl group at the N7-position with benzyl (Bn) produces a dinucleotide cap with superior properties. Here, we followed up on this finding by synthesizing 17 novel Bn7GpppG analogs and determining their structure–activity relationship regarding translation and translational inhibition. The compounds were prepared in two steps, including selective N7-alkylation of guanosine 5′-monophosphate by arylmethyl bromide followed by coupling with imidazole-activated GDP, with total yields varying from 22% to 62%. The compounds were then evaluated by determining their affinity for eukaryotic translation initiation factor 4E (eIF4E), testing their susceptibility to decapping pyrophosphatase, DcpS—which is most likely the major cellular enzyme targeting this type of compound—and determining their translation inhibitory properties in vitro. We also synthesized mRNAs capped with the evaluated compounds and tested their translational properties in A549 cells. Our studies identified N7-(4-halogenbenzyl) substituents as promising modifications in the contexts of either mRNA translation or translational inhibition. Finally, to gain more insight into the consequences at the molecular level of N7-benzylation of the mRNA cap, we determined the crystal structures of three compounds with eIF4E

Sulfanyl porphyrazines: Molecular barrel-like self-assembly in crystals, optical properties and in vitro photodynamic activity towards cancer cells

Novel sulfanyl porphyrazines with peripheral 4-bromobenzyl and 4-biphenylylmethyl substituents were synthesized, characterized by photochemical methods and evaluated as sensitizers for photodynamic therapy (PDT). The X-ray crystallography study performed for sulfanyl porphyrazine with 4-biphenylylmethyl substituents revealed that the biphenylyl residues from two consecutive molecules form barrel-like cages with a macrocyclic core constituting a bottom and a top of the barrel and pyridine molecules enclosed inside. The optical properties of both porphyrazines were evaluated in various protic and aprotic solvents. To complement the conventional fluorescence measurements excitation-emission maps were recorded. The potential photosensitizing efficiency of the novel sulfanyl porphyrazines was evaluated by assessing the quantum yields of photosensitized singlet oxygen production. For this purpose the emission of light specific for the transition of singlet oxygen to ground state oxygen was measured. Photodynamic activities of porphyrazines and their liposomal formulations with different surface charge toward two oral squamous cell carcinoma cells (CAL 27, HSC-3) and human cervical epithelial adenocarcinoma cells (HeLa) were determined. Sulfanyl porphyrazines incorporated in cationic liposomes showed high activity, in contrast to the lack of activity of the free form porphyrazines in solution. Thus, cationic liposomes composed of 1,2-dioleoyl-3-trimethylammonium-propane and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine can be considered as a promising drug delivery system for the sulfanyl porphyrazines for the photodynamic therapy of cancers

Tetramethylalloxazines as efficient singlet oxygen photosensitizers and potential redox-sensitive agents

Abstract Tetramethylalloxazines (TMeAll) have been found to have a high quantum yield of singlet oxygen generation when used as photosensitizers. Their electronic structure and transition energies (S0 → Si, S0 → Ti, T1 → Ti) were calculated using DFT and TD-DFT methods and compared to experimental absorption spectra. Generally, TMeAll display an energy diagram similar to other derivatives belonging to the alloxazine class of compounds, namely π,π* transitions are accompanied by closely located n,π* transitions. Photophysical data such as quantum yields of fluorescence, fluorescence lifetimes, and nonradiative rate constants were also studied in methanol (MeOH), acetonitrile (ACN), and 1,2-dichloroethane (DCE). The transient absorption spectra were also analyzed. To assess cytotoxicity of new compounds, a hemolytic assay was performed using human red blood cells (RBC) in vitro. Subsequently, fluorescence lifetime imaging experiments (FLIM) were performed on RBC under physiological and oxidative stress conditions alone or in the presence of TMeAll allowing for pinpointing changes caused by those compounds on the intracellular environment of these cells

Evaluation of Polysaccharide–Peptide Conjugates Containing the RGD Motif for Potential Use in Muscle Tissue Regeneration

New scaffold materials composed of biodegradable components are of great interest in regenerative medicine. These materials should be: stable, nontoxic, and biodegrade slowly and steadily, allowing the stable release of biodegradable and biologically active substances. We analyzed peptide-polysaccharide conjugates derived from peptides containing RGD motif (H-RGDS-OH (1), H-GRGDS-NH2 (2), and cyclo(RGDfC) (3)) and polysaccharides as scaffolds to select the most appropriate biomaterials for application in regenerative medicine. Based on the results of MTT and Ki-67 assays, we can state that the conjugates containing calcium alginate and the ternary nonwoven material were the most supportive of muscle tissue regeneration. Scanning electron microscopy imaging and light microscopy studies with hematoxylin–eosin staining showed that C2C12 cells were able to interact with the tested peptide–polysaccharide conjugates. The release factor (Q) varied depending on both the peptide and the structure of the polysaccharide matrix. LDH, Alamarblue®, Ki-67, and cell cycle assays indicated that peptides 1 and 2 were characterized by the best biological properties. Conjugates containing chitosan and the ternary polysaccharide nonwoven with peptide 1 exhibited very high antibacterial activity against Staphylococcus aureus and Klebsiella pneumoniae. Overall, the results of the study suggested that polysaccharide conjugates with peptides 1 and 2 can be potentially used in regenerative medicine