Dependence of the Protective Properties of Mixtures Based on Several Reaction Series on the Number and Concentrations of the Components

Mixtures based on azomethine, imidazobenzoimidazole, and pyrimidobenzoimidazole derivatives were tested as inhibitors of iron corrosion in 1 M H₂SO₄ in the presence of 0.25 mol/l NaCl. The number and concentrations of their components were varied with the aim of studying their influence on the protection effects of the mixtures. The resulting experimental dependences, of the protective effectiveness on the number and concentration of the components, as well as the polar properties of substituents in their molecules, can be interpreted in terms of the linear Gibbs energy relation (LGER). This conclusion is valid over a wide range of medium temperatures (20–60°C), provided the volume concentrations of compounds in each reaction series are kept constant.     

Free radical polymerization in ionic liquids—Influence of the IL-concentration and temperature

The influence of the ionic liquid (IL) 1-ethyl-3-methylimidazoliumethylsulfate ([EMIM]EtSO₄) on the polymerization kinetics of methyl methacrylate was investigated. ILs are liquids with relatively high polarities and viscosities. These two characteristic properties are strongly correlated with the rate coefficients of propagation k_p and termination k_t of polymerizations carried out in ILs. The rate constant of termination k_t decreases when the concentration of ionic liquid, and thus the viscosity is increased, whereas the propagation rate coefficient k_p increases with increasing IL content. The viscosity of ILs can be varied by either working with mixtures of ILs with conventional organic solvents – here the IL [EMIM]EtSO₄ was mixed with dimethyl formamide (DMF) – or by variation of the temperature. The studies were carried out to determine the influence of the viscosity on the propagation and the termination reaction as well as the molecular weight distribution.     

Using statistical models to identify factors that have a role in defining the abundance of ions produced by tandem MS

A database of 5448 peptide tandem mass spectra acquired in a quadrupole time-of-flight mass spectrometer was generated for peptides derived from proteins digested with trypsin. Peptides were identified from their mass spectra by the Mascot algorithm. Statistical models were then used to investigate factors influencing the abundance of ions formed. Separate models were formulated for b and y ions as it was thought that different factors may influence the formation of each type of ion. Several factors were found to have a highly significant influence on the abundance of ions formed. These include the actual mass of the ion formed after fragmentation as well as the location of the cleavage. The composition of the fragmenting peptide was also found to be important, and amino acids either side of the fragmentation site influenced the abundance of ions produced. To increase understanding of fragmentation mechanisms, the effect of several physicochemical properties of these residues was also investigated in a separate model. In conclusion, the models formulated for b and y ions provide useful characterization of the abundance of ions formed, and this information could be used to develop improved algorithms for peptide identification.     

Influence of hydrogen on the deformation morphology of vanadium (1 0 0) micropillars in the α-phase of the vanadium–hydrogen system

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Co-Stimulation of Oxytocin and Arginine-Vasopressin Receptors Affect Hypothalamic Neurospheroid Size

Oxytocin (OXT) is a neuropeptide involved in a plethora of behavioral and physiological processes. However, there is a prominent lack of 3D cell culture models that investigate the effects of OXT on a cellular/molecular level. In this study, we established a hypothalamic neuronal spheroid model to investigate the cellular response in a more realistic 3D setting. Our data indicate that the formation of spheroids itself does not alter the basic characteristics of the cell line and that markers of cellular morphology and connectivity are stably expressed. We found that both OXT and arginine vasopressin (AVP) treatment increase spheroid size (surface area and volume), as well as individual nucleus size, which serves as an indicator for cellular proliferation. The cellular response to both OXT and AVP seems mainly to be mediated by the AVP receptor 1a (V1aR); however, the OXT receptor (OXTR) contributes significantly to the observed proliferative effect. When we blocked the OXTR pharmacologically or knocked down the OXTR by siRNA, the OXT- or AVP-induced cellular proliferation decreased. In summary, we established a 3D cell culture model of the neuronal response to OXT and AVP and found that spheroids react to the treatment via their respective receptors but also via cross-talk between the two receptor types.     

Modulation of the Cardiac Myocyte Action Potential by the Magnesium-Sensitive TRPM6 and TRPM7-like Current

The cardiac Mg²⁺-sensitive, TRPM6, and TRPM7-like channels remain undefined, especially with the uncertainty regarding TRPM6 expression in cardiomyocytes. Additionally, their contribution to the cardiac action potential (AP) profile is unclear. Immunofluorescence assays showed the expression of the TRPM6 and TRPM7 proteins in isolated pig atrial and ventricular cardiomyocytes, of which the expression was modulated by incubation in extracellular divalent cation-free conditions. In patch clamp studies of cells dialyzed with solutions containing zero intracellular Mg²⁺ concentration ([Mg²⁺]_i) to activate the Mg²⁺-sensitive channels, raising extracellular [Mg²⁺] ([Mg²⁺]_o) from the 0.9-mM baseline to 7.2 mM prolonged the AP duration (APD). In contrast, no such effect was observed in cells dialyzed with physiological [Mg²⁺]_i. Under voltage clamp, in cells dialyzed with zero [Mg²⁺]_i, depolarizing ramps induced an outward-rectifying current, which was suppressed by raising [Mg²⁺]_o and was absent in cells dialyzed with physiological [Mg²⁺]_i. In cells dialyzed with physiological [Mg²⁺]_i, raising [Mg²⁺]_o decreased the L-type Ca²⁺ current and the total delayed-rectifier current but had no effect on the APD. These results suggest a co-expression of the TRPM6 and TRPM7 proteins in cardiomyocytes, which are therefore the molecular candidates for the native cardiac Mg²⁺-sensitive channels, and also suggest that the cardiac Mg²⁺-sensitive current shortens the APD, with potential implications in arrhythmogenesis.     

Lactobacilli isolated from the Armenian fermented milk product matsoun: Growth properties,antibacterial and proteolytic activity and their dependence on pH

Growth, antibacterial and proteolytic activities of two new lactobacilli strains isolated from matsoun (Armenian traditional dairy product) and their pH dependence were studied. The results demonstrated the antibacterial activity of lactobacilli against Gram‐positive and Gram‐negative test strains. This activity was stable when pH of cell culture medium was adjusted to the value of 6.5. At pH 8, the antibacterial activity of only one strain was stable. Both strains were able to hydrolyse casein in pH range of 5.5–8 with maximal activity at pH 5.5. Controlled pH conditions were suitable for biomass yield, while noncontrolled pH was better for expression of antibacterial activity.     

Changes in the Profiles of Metabolites Originating from Protein Degradation During Ripening of Dry Cured Ham

Ripening of dry cured ham involves a high number of complex enzymatic and chemical reactions. Due to long processing time, there is a need for analytical methods that can be applied to monitor the ripening in optimization of process conditions and development of new products. In this study, nontargeted metabolite analysis by mass spectrometry (MS) was employed to determine the ripening rates at different water activities in small-scale laboratory experiments and to follow the progress of the ripening of hams from a dry cured ham production facility. Approximately 1000 metabolites were detected. Of these, 90–95% had molecular masses below 800 Da, and more than 60% below 500 Da. In the order of 150 metabolites were putatively annotated. In addition to free amino acids and muscle metabolites, the nontargeted analysis revealed the time profiles of di- and tripeptides, as well as a high number of compounds generated by further conversion of amino acids, muscle metabolites and probably lipids. Statistical processing of the data sets showed that the metabolite profiles changed with the storage time, and that ripening of fresh and unsalted, dried meat, generated other profiles than salted samples. In conclusion, our approach represents a simple and efficient tool for comparison of process conditions and to follow the time course of the ripening, useful in product development and process optimization.     

The Effects of Sperm and Seminal Fluid of Immunized Male Mice on In Vitro Fertilization and Surrogate Mother–Embryo Interaction

The latest vaccination campaign has actualized the potential impact of antigenic stimuli on reproductive functions. To address this, we mimicked vaccination’s effects by administering keyhole limpet hemocyanin (KLH ) to CD1 male mice and used their sperm for in vitro fertilization (IVF). Two-cell embryos after IVF with spermatozoa from control (C) or KLH-treated (Im) male mice were transferred to surrogate mothers mated with vasectomized control (C) or KLH-treated (Im) male mice, resulting in four experimental groups: C–C, Im–C, C–Im, and Im–Im. The pre-implantation losses were significantly lower in the Im–C group than in the C–Im group. At the same time, the resorption rates reduced markedly in the C–Im compared to the Im–C group. Embryo and placenta weights were significantly higher in the Im–Im group. Although the GM-CSF levels were lower in the amniotic fluid of the gestating surrogate mothers in the Im–Im group, they were strongly correlated with embryo mass. The number–size trade-off was only significant in the Im–Im group. This suggests a positive, cooperative effect of spermatozoa and seminal fluid from immune-primed males on embryo growth and the optimal distribution of surrogate mother maternal resources despite the negative impact of males’ antigenic challenge on the IVF success rate.