Chronic exposure to zinc oxide nanoparticles increases ischemic-reperfusion injuries in isolated rat hearts

The use of zinc oxide nanoparticles (ZnO NPs) in numerous products is increasing, although possible negative implications of their long-term consumption are not known yet. Our aim was to evaluate the chronic, 6-week oral exposure to two different concentrations of ZnO NPs on isolated rat hearts exposed to ischemic-reperfusion injury and on small intestine morphology. Wistar rats of both sexes (n = 18) were randomly divided into three groups: (1) 4 mg/kg ZnO NPs, (2) 40 mg/kg ZnO NPs, and (3) control. After 6 weeks of treatment, the hearts were isolated, the left ventricular pressure (LVP), the coronary flow (CF), the duration of arrhythmias and the lactate dehydrogenase release rate (LDH) were measured. A histological investigation of the small intestine was performed. Chronic exposure to ZnO NPs acted cardiotoxic dose-dependently. ZnO NPs in dosage 40 mg/kg maximally decreased LVP (3.3-fold) and CF (2.5-fold) and increased the duration of ventricular tachycardia (all P < 0.01) compared to control, whereas ZnO NPs in dosage 4 mg/kg acted less cardiotoxic. Goblet cells in the small intestine epithelium of rats, treated with 40 mg ZnO NPs/kg, were enlarged, swollen and numerous, the intestinal epithelium width was increased. Unexpectedly, ZnO NPs in both dosages significantly decreased LDH. A 6-week oral exposure to ZnO NPs dose-dependently increased heart injuries and caused irritation of the intestinal mucosa. A prolonged exposure to ZnO NPs might cause functional damage to the heart even with exposures to the recommended daily doses, which should be tested in future studies.     

Synthesis and structure of <Emphasis Type="Italic">N</Emphasis>-substituted (1-ferrocenylethyl)amine derivatives

N-Acetyl-(1-ferrocenylethyl)amine (8) was synthesized by N-acylation of (1-ferrocenylethyl)amine (7) in 84% yield. Reaction of N-acetyl-[1-(1′-bromo-ferrocenyl)ethyl]amine (4) (which was prepared by multistep sequence starting from bromoferrocene) with n-BuLi/ClCOOEt gave 77% of N-acetyl-N-ethoxycarbonyl-(1-ferrocenylethyl)amine (6) instead of the expected ethyl 1′-[1-(acetamido)ethyl]ferrocene-1-carboxylate (5). Both structures were undoubtedly confirmed by (HR)MS spectroscopy and single crystal X-ray structure analysis.     

Ferrocene-dipeptide conjugates derived from aminoferrocene and 1-acetyl-1′-aminoferrocene: synthesis and conformational studies

In this study we present the synthesis and conformational analysis of mono- and disubstituted ferrocene bioconjugates bearing dipeptide chains (Boc-AA-AA-Fn-X, AA=Gly, l-Ala, l-Val). The conformational preferences of novel aminoferrocene derived conjugates with X=H, as well as their 1-acetyl analogues (X=COMe), were investigated by spectroscopic techniques (IR, NMR and CD) and corroborated by DFT calculations. Chirally organized structures, stabilized through intrachain hydrogen bonds, prevail in solution when X=H. The resulting 10-membered hydrogen-bond ring is destabilized by heteroannular introduction of an acetyl group when X=COMe.     

The Use of 4-Cyanoaminomethylene-2-phenyl-5(4h)-oxazolone in the Synthesis of Some Heteroarylaminomethylene Substituted 5(4H)-Oxazolones

The use of 4-cyanoaminomethylene-2-phenyl-5(4H)-oxazolone in the synthesis of some 4-heteroarylaminomethylene-2-phenyl-5(4H)-oxazolones was studied. Synthesis of 4-(1,2,4-oxadiazol-3-yl)aminomethylene-2-phenyl-5(4H)-oxazolone is described.     

Mechanisms involved in gene electrotransfer using high- and low-voltage pulses--an in vitro study

Gene electrotransfer is an established method for gene delivery which uses high-voltage pulses to increase permeability of cell membrane and thus enables transfer of genes. Currently, majority of research is focused on improving in vivo transfection efficiency, while mechanisms involved in gene electrotransfer are not completely understood. In this paper we analyze the mechanisms of gene electrotransfer by using combinations of high-voltage (HV) and low-voltage pulses (LV) in vitro. We applied different combinations of HV and LV pulses to CHO cells and determined the transfection efficiency. We obtained that short HV pulses alone were sufficient to deliver DNA into cells for optimal plasmid concentrations and that LV pulse did not increase transfection efficiency, in contrast to reported studies in vivo. However, for sub-optimal plasmid concentrations combining HV and LV pulses increased transfection rate. Our results suggest that low-voltage pulses increase transfection in conditions where plasmid concentration is low, typically in vivo where mobility of DNA is limited by the extracellular matrix. LV pulses provide additional electrophoretic force which drags DNA toward the cell membrane and consequently increase transfection efficiency, while for sufficiently high concentrations of the plasmid (usually used in vitro) electrophoretic LV pulses do not have an important role.     

Layered photoconductive polymers: anisotropic morphology and correlation with photorefractive reflection grating response

We demonstrate that the mesophase morphology of the layered photorefractive polymers has a substantial influence on the photorefractive properties, especially in reflection grating geometries with a minimal grating spacing. The layered morphology of the photoconductive polymers based on poly(p-phenyleneterephthalate) (PPT) with pendent carbazole (CZ) groups can be efficiently controlled by changing their molecular weight. Photorefractive composites based on PPT-CZ polymers with different chromophores, diethylaminodicyanostyrene (DDCST) or piperidinodicyanostyrene (PDCST), show anisotropic morphology induced by the squeezing flow during sample preparation. The contributions of the highest occupied molecular orbital levels of the chromophores and of the degree and anisotropy of the layered crystalline structure to the charge transport and trapping result in a high efficiency of the PDCST composite and a similar response speed in DDCST and PDCST composites in the reflection grating geometry, although of about six times lower photoconductivity in the less-ordered PDCST composite.     

Supercritical Carbon Dioxide Extraction of Four Medicinal Mediterranean Plants: Investigation of Chemical Composition and Antioxidant Activity

With everyday advances in the field of pharmaceuticals, medicinal plants have high priority regarding the introduction of novel synthetic compounds by the usage of environmentally friendly extraction technologies. Herein, a supercritical CO₂ extraction method was implemented in the analysis of four plants (chamomile, St. John’s wort, yarrow, and curry plant) after which the non-targeted analysis of the chemical composition, phenolic content, and antioxidant activity was evaluated. The extraction yield was the highest for the chamomile (5%), while moderate yields were obtained for the other three plants. The chemical composition analyzed by gas chromatography-high-resolution mass spectrometry (GC-HRMS) and liquid chromatography-high-resolution mass spectrometry (LC-HRMS) demonstrated extraction of diverse compounds including terpenes and terpenoids, fatty acids, flavonoids and coumarins, functionalized phytosterols, and polyphenols. Voltammetry of microfilm immobilized on a glassy carbon electrode using square-wave voltammetry (SWV) was applied in the analysis of extracts. It was found that antioxidant activity obtained by SWV correlates well to 1,1-diphenyl-2-picrylhidrazine (DPPH) radical assay (R² = 0.818) and ferric reducing antioxidant power (FRAP) assay (R² = 0.640), but not to the total phenolic content (R² = 0.092). Effective results were obtained in terms of activity showing the potential usage of supercritical CO2 extraction to acquire bioactive compounds of interest.     

Comparison of bacterial and phage display peptide libraries in search of target-binding motif

Genetic engineering allows modification of bacterial and bacteriophage genes, which code for surface proteins, enabling display of random peptides on the surface of these microbial vectors. Biologic peptide libraries thus formed are used for high-throughput screening of clones bearing peptides with high affinity for target proteins. There are reports of many successful affinity selections performed with phage display libraries and substantially fewer cases describing the use of bacterial display systems. In theory, bacterial display has some advantages over phage display, but the two systems have never been experimentally compared. We tested both techniques in selecting streptavidin-binding peptides from two commercially available libraries. Under similar conditions, selection of phage-displayed peptides to model protein streptavidin proved convincingly better.     

Thermodynamic analysis of the interaction of partially hydrophobic cationic polyelectrolytes with sodium halide salts in water

Isothermal titration calorimetry was used to determine the temperature and concentration dependence of the enthalpy of mixing of 3,3- and 6,6-ionene fluorides, bromides, and iodides with low molecular weight salts (NaF, NaCl, NaBr, and NaI) in water. The magnitudes of the enthalpies, measured in the temperature range from 273 to 318 K, depended on the number of methylene groups on the ionene polyion (hydrophobicity), and on the anion of the added salt (ion-specificity). All enthalpies of mixing of 3,3- and 6,6-ionene fluorides with low molecular weight salts (NaCl, NaBr, and NaI) were negative, which is in contrast to the predictions of standard theories of polyelectrolyte solutions. This fact was interpreted in the light of the ion–water short-range interactions that are not accounted for in those theories. In contrast, the enthalpies of mixing of 3,3- and 6,6-ionene bromides and iodides with NaF were positive, being in accord with theory. Using the calorimetric data, we performed a model thermodynamic analysis of the polyelectrolyte–salt mixing process to obtain changes in the apparent standard Gibbs free energy, enthalpy, entropy, and heat capacity relative to the pure ionene fluorides in water. The results prove that halide ions replace fluoride counterions with a strength increasing in the order chloride < bromide < iodide. The process is enthalpy governed, accompanied by a positive change in the heat capacity.     

Preparation and characterisation of ribonuclease monolithic bioreactor

In gene therapy and DNA vaccination, RNA removal from DNA preparations is vital and is typically achieved by the addition of ribonuclease into the sample. Removal of ribonuclease from DNA samples requires an additional purification step. An alternative is the implementation of immobilized ribonuclease. In our work, ribonuclease was covalently coupled onto the surface of methacrylate monoliths via epoxy or imidazole carbamate groups. Various immobilization conditions were tested by changing immobilization pH. Ribonuclease immobilized on the monolith via imidazole carbamate groups at pH 9 was found to be six times more active than the ribonuclease immobilized on the monolith via epoxy groups. Under optimal immobilization conditions the Michaelis-Menten constant, Km, for cytidine-2,3-cyclic monophosphate, and turnover number, k3 were 0.52 mM and 4.6s(-1), respectively, and mirrored properties of free enzyme. Enzyme reactor was found to efficiently eliminate RNA contaminants from DNA samples. It was active for several weeks of operation and processed 300 column volumes of sample. Required residence time to eliminate RNA was estimated to be around 0.5 min enabling flow rates above 1 column volume per min.