Spontaneous emission of color centers at 4eV in hexagonal boron nitride under hydrostatic pressure

The light emission properties of color centers emitting in 3.3-4 eV region are investigated for hydrostatic pressures ranging up to 5GPa at liquid helium temperature. The light emission energy decreases with pressure less sensitively than the bandgap. This behavior at variance from the shift of the bandgap is typical of deep traps. Interestingly, hydrostatic pressure reveals the existence of levels that vary differently under pressure (smaller increase of the emission wavelength compared to the rest of the levels in this energy region or even decrease of it) with pressure. This discovery enriches the physics of the color centers operating in the UV in hBN.Comment: 16 pages, 3 figure

Search for fibrous aggregates potentially useful in regenerative medicine formed under physiological conditions by self-assembling short peptides containing two identical aromatic amino acid residues

This study investigates the propensity of short peptides to self-organize and the influence of aggregates on cell cultures. The dipeptides were derived from both enantiomers of identical aromatic amino acids and tripeptides were prepared from two identical aromatic amino acids with one cysteine or methionine residue in the C-terminal, N-terminal, or central position. The formation or absence of fibrous structures under physiological conditions was established using Congo Red and Thioflavine T assays as well as by microscopic examination using normal and polarized light. The in vitro stability of the aggregates in buffered saline solution was assessed over 30 days. Materials with potential for use in regenerative medicine were selected based on the cytotoxicity of the peptides to the endothelial cell line EA.hy 926 and the wettability of the surfaces of the films, as well as using scanning electron microscopy. The criteria were fulfilled by H-dPhedPhe-OH, H-dCysdPhedPhe-OH, H-CysTyrTyr-OH, H-dPhedPhedCys-OH, H-TyrTyrMet-OH, and H–TyrMetTyr–OH. Our preliminary results suggest that the morphology and cell viability of L919 fibroblast cells do not depend on the stereochemistry of the self-organizing peptides

Investigating the Effects of Statins on Cellular Lipid Metabolism Using a Yeast Expression System

In humans, defects in lipid metabolism are associated with a number of severe diseases such as atherosclerosis, obesity and type II diabetes. Hypercholesterolemia is a primary risk factor for coronary artery disease, the major cause of premature deaths in developed countries. Statins are inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), the key enzyme of the sterol synthesis pathway. Since yeast Saccharomyces cerevisiae harbours many counterparts of mammalian enzymes involved in lipid-synthesizing pathways, conclusions drawn from research with this single cell eukaryotic organism can be readily applied to higher eukaryotes. Using a yeast strain with deletions of both HMG1 and HMG2 genes (i.e. completely devoid of HMGR activity) with introduced wild-type or mutant form of human HMGR (hHMGR) gene we investigated the effects of statins on the lipid metabolism of the cell. The relative quantification of mRNA demonstrated a different effect of simvastatin on the expression of the wild-type and mutated hHMGR gene. GC/MS analyses showed a significant decrease of sterols and enhanced conversion of squalene and sterol precursors into ergosterol. This was accompanied by the mobilization of ergosterol precursors localized in lipid particles in the form of steryl esters visualized by confocal microscopy. Changes in the level of ergosterol and its precursors in cells treated with simvastatin depend on the mutation in the hHMGR gene. HPLC/MS analyses indicated a reduced level of phospholipids not connected with the mevalonic acid pathway. We detected two significant phenomena. First, cells treated with simvastatin develop an adaptive response compensating the lower activity of HMGR. This includes enhanced conversion of sterol precursors into ergosterol, mobilization of steryl esters and increased expression of the hHMGR gene. Second, statins cause a substantial drop in the level of glycerophospholipids

Delivery of the VIVIT Peptide to Human Glioma Cells to Interfere with Calcineurin-NFAT Signaling

The activation of NFAT (nuclear factor of activated T cells) transcription factors by calcium-dependent phosphatase calcineurin is a key step in controlling T cell activation and plays a vital role during carcinogenesis. NFATs are overexpressed in many cancers, including the most common primary brain tumor, gliomas. In the present study, we demonstrate the expression of NFATs and NFAT-driven transcription in several human glioma cells. We used a VIVIT peptide for interference in calcineurin binding to NFAT via a conserved PxIxIT motif. VIVIT was expressed as a fusion protein with a green fluorescent protein (VIVIT-GFP) or conjugated to cell-penetrating peptides (CPP), Sim-2 or 11R. We analyzed the NFAT expression, phosphorylation, subcellular localization and their transcriptional activity in cells treated with peptides. Overexpression of VIVIT-GFP decreased the NFAT-driven activity and inhibited the transcription of endogenous NFAT-target genes. These effects were not reproduced with synthetic peptides: Sim2-VIVIT did not show any activity, and 11R-VIVIT did not inhibit NFAT signaling in glioma cells. The presence of two calcineurin docking sites in NFATc3 might require dual-specificity blocking peptides. The cell-penetrating peptides Sim-2 or 11R linked to VIVIT did not improve its action making it unsuitable for evaluating NFAT dependent events in glioma cells with high expression of NFATc3

Quality of Dietary Supplements Containing Plant-Derived Ingredients Reconsidered by Microbiological Approach

Dietary supplements cover a wide range of products, the most popular are those containing plant-based ingredients. Supplements are consumed by consumers of all ages as well as by both healthy and sick people. The lack of unified regulation in this sector increases the probability that supplements are poor chemical and microbiological quality and can be dangerous for patients. The aim of this paper is to highlight selected issues associated with the microbiological quality of dietary supplements containing plant materials. We focus on the most recent reports referring to bacterial and fungal contaminations as well as the presence of mycotoxins. Dietary supplements containing plant ingredients commonly show a variety of microbial contaminants, which might be crucial for consumer safety. They often contain microorganisms potentially pathogenic to humans. Metabolites produced by microorganisms may pose a threat to the health of consumers. Because of that, in this review, we emphasize the risk that may be associated with the lack of appropriate studies of the quality of the supplements

Stress level and life satisfaction among academic athletes

Wstęp. Stres jest nieodłącznym elementem życia, a jego długotrwałe doświadczanie może mieć negatywny wpływ na zdrowie fizyczne i psychiczne człowieka. Sportowcy akademiccy mogą być szczególnie narażeni na stres ze względu na konieczność łączenia treningów z obowiązkami akademickimi. Celem badań było ustalenie powiązań pomiędzy poziomem odczuwanego stresu a poczuciem satysfakcji z życia u sportowców akademickich z uwzględnieniem płci i rodzaju uprawianej dyscypliny. Założono, że wyższy poziom stresu wiąże się z niższym poziomem satysfakcji z życia. Materiał i metody. Badaniem objętych zostało 209 sportowców akademickich (153 mężczyzn i 56 kobiet), uprawiających różne dyscypliny indywidualne i zespołowe. Wykorzystano Skalę Odczuwanego Stresu (PSS-10) oraz Skalę Satysfakcji z Życia (SWLS). Dodatkowo, za pośrednictwem ankiety, zebrano informacje na temat uprawianej dyscypliny sportu. Wyniki. Niższy poziom odczuwanego stresu wiąże się z wyższym poziomem satysfakcji z życia w grupie sportowców akademickich (zarówno wśród kobiet, jak i mężczyzn, a także po uwzględnieniu podziału na typ uprawianej dyscypliny sportowej tj. indywidualna vs zespołowa). Satysfakcja z życia kobiet, biorących udział w badaniu własnym, była wyższa w porównaniu z mężczyznami, natomiast pod względem poziomu odczuwanego stresu nie wystąpiły pomiędzy nimi istotne różnice. Rodzaj uprawianej dyscypliny nie różnicował wyników w zakresie poziomu odczuwanego stresu i satysfakcji życiowej. Wnioski. Wyniki badań wskazują na rolę jaką w poczuciu satysfakcji z życia ogrywa poziom odczuwanego stresu. W badanej grupie – sportowców akademickich, temat ten wydaje się być szczególnie ważny i zasługuje na dalsze analizy.Background. While stress is an integral part of human life, being exposed to it for a more extended period can have a negative impact on a person’s physical and mental health. Academic athletes may be particularly exposed to stress due to the need to combine sports training with academic duties. The study aimed to establish the connections between the level of stress and life satisfaction among academic athletes, with regard to their gender and the type of discipline practised. It was assumed that a higher level of stress is associated with a lower level of life satisfaction. Material and methods. The study included 209 academic athletes (153 men and 56 women), practising various individual and team sports. The Perceived Stress Scale (PSS-10) and the Satisfaction with Life Scale (SWLS) were used. Additionally, the information about the sports being practised was collected via the survey. Results. The lower level of the perceived stress is associated with a higher level of life satisfaction in the group of academic athletes (both among women and men, and also taking into account the division into the type of sport practised, i.e. individual vs team one). Life satisfaction among women who took part in the study was higher than among men; however, in terms of the level of the perceived stress, there were no significant differences between the two groups. The type of discipline practised did not differentiate the results of the level of the perceived stress and the life satisfaction. Conclusions. The results of the research indicate the role that the level of the perceived stress has for the sense of satisfaction with one’s life. This issue seems to be particularly relevant in the surveyed group, i.e. academic athletes, that deserves further analysis