Functionalized Peptide Fibrils as a Scaffold for Active Substances in Wound Healing

Technological developments in the field of biologically active peptide applications in medicine have increased the need for new methods for peptide delivery. The disadvantage of peptides as drugs is their low biological stability. Recently, great attention has been paid to self-assembling peptides that can form fibrils. Such a formulation makes bioactive peptides more resistant to enzymatic degradation and druggable. Peptide fibrils can be carriers for peptides with interesting biological activities. These features open up prospects for using the peptide fibrils as long-acting drugs and are a valid alternative to conventional peptidic therapies. In our study, we designed new peptide scaffolds that are a hybrid of three interconnected amino acid sequences and are: pro-regenerative, cleavable by neutrophilic elastase, and fibril-forming. We intended to obtain peptides that are stable in the wound environment and that, when applied, would release a biologically active sequence. Our studies showed that the designed hybrid peptides show a high tendency toward regular fibril formation and are able to release the pro-regenerative sequence. Cytotoxicity studies showed that all the designed peptides were safe, did not cause cytotoxic effects and revealed a pro-regenerative potential in human fibroblast and keratinocyte cell lines. In vivo experiments in a dorsal skin injury model in mice indicated that two tested peptides moderately promote tissue repair in their free form. Our research proves that peptide fibrils can be a druggable form and a scaffold for active peptides.     

Dopamine D2 Receptor Agonist Binding Kinetics—Role of a Conserved Serine Residue

The forward (k_on) and reverse (k_off) rate constants of drug–target interactions have important implications for therapeutic efficacy. Hence, time-resolved assays capable of measuring these binding rate constants may be informative to drug discovery efforts. Here, we used an ion channel activation assay to estimate the k_ons and k_offs of four dopamine D₂ receptor (D₂R) agonists; dopamine (DA), p-tyramine, (R)- and (S)-5-OH-dipropylaminotetralin (DPAT). We further probed the role of the conserved serine S193^5.42 by mutagenesis, taking advantage of the preferential interaction of (S)-, but not (R)-5-OH-DPAT with this residue. Results suggested similar k_offs for the two 5-OH-DPAT enantiomers at wild-type (WT) D₂R, both being slower than the k_offs of DA and p-tyramine. Conversely, the k_on of (S)-5-OH-DPAT was estimated to be higher than that of (R)-5-OH-DPAT, in agreement with the higher potency of the (S)-enantiomer. Furthermore, S193^5.42A mutation lowered the k_on of (S)-5-OH-DPAT and reduced the potency difference between the two 5-OH-DPAT enantiomers. Kinetic K_ds derived from the k_off and k_on estimates correlated well with EC₅₀ values for all four compounds across four orders of magnitude, strengthening the notion that our assay captured meaningful information about binding kinetics. The approach presented here may thus prove valuable for characterizing D₂R agonist candidate drugs.     

Effect of Posttranslational Modifications on the Structure and Activity of FTO Demethylase

The FTO protein is involved in a wide range of physiological processes, including adipogenesis and osteogenesis. This two-domain protein belongs to the AlkB family of 2-oxoglutarate (2-OG)- and Fe(II)-dependent dioxygenases, displaying N⁶-methyladenosine (N⁶-meA) demethylase activity. The aim of the study was to characterize the relationships between the structure and activity of FTO. The effect of cofactors (Fe²⁺/Mn²⁺ and 2-OG), Ca²⁺ that do not bind at the catalytic site, and protein concentration on FTO properties expressed in either E. coli (^ECFTO) or baculovirus (^BESFTO) system were determined using biophysical methods (DSF, MST, SAXS) and biochemical techniques (size-exclusion chromatography, enzymatic assay). We found that ^BESFTO carries three phosphoserines (S184, S256, S260), while there were no such modifications in ^ECFTO. The S256D mutation mimicking the S256 phosphorylation moderately decreased FTO catalytic activity. In the presence of Ca²⁺, a slight stabilization of the FTO structure was observed, accompanied by a decrease in catalytic activity. Size exclusion chromatography and MST data confirmed the ability of FTO from both expression systems to form homodimers. The MST-determined dissociation constant of the FTO homodimer was consistent with their in vivo formation in human cells. Finally, a low-resolution structure of the FTO homodimer was built based on SAXS data.     

Rheological Model for Simulation of Hot rolling of New Generation Steel Strips for Automotive Applications

The main objective of this paper is the development of a rheological model for automotive steels for the conditions of hot strip rolling and implementation of this model in a finite element program is. Three types of steels were investigated, IF, dual phase and TRIP steel. Plastometric tests were performed on a Gleeble 3800 simulator for the temperature range 850‐1200°C and strain rates 3‐150 s^?1. Inverse analysis was applied to eliminate the influence of disturbances occurring in the plastometric tests and to determine the real flow stress of the material. The coefficients in the flow stress equation were evaluated and this equation was implemented in the FEM code as the constitutive law. The model was validated by comparison of measured and calculated loads in the compression tests and by strip rolling experiments conducted in the laboratory mill. Validation confirmed a good predictive capability of the rheological model.     

Inhibition of Carotenoid Biosynthesis by CRISPR/Cas9 Triggers Cell Wall Remodelling in Carrot

Recent data indicate that modifications to carotenoid biosynthesis pathway in plants alter the expression of genes affecting chemical composition of the cell wall. Phytoene synthase (PSY) is a rate limiting factor of carotenoid biosynthesis and it may exhibit species-specific and organ-specific roles determined by the presence of psy paralogous genes, the importance of which often remains unrevealed. Thus, the aim of this work was to elaborate the roles of two psy paralogs in a model system and to reveal biochemical changes in the cell wall of psy knockout mutants. For this purpose, Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR associated (Cas9) proteins (CRISPR/Cas9) vectors were introduced to carotenoid-rich carrot (Daucus carota) callus cells in order to induce mutations in the psy1 and psy2 genes. Gene sequencing, expression analysis, and carotenoid content analysis revealed that the psy2 gene is critical for carotenoid biosynthesis in this model and its knockout blocks carotenogenesis. The psy2 knockout also decreased the expression of the psy1 paralog. Immunohistochemical staining of the psy2 mutant cells showed altered composition of arabinogalactan proteins, pectins, and extensins in the mutant cell walls. In particular, low-methylesterified pectins were abundantly present in the cell walls of carotenoid-rich callus in contrast to the carotenoid-free psy2 mutant. Transmission electron microscopy revealed altered plastid transition to amyloplasts instead of chromoplasts. The results demonstrate for the first time that the inhibited biosynthesis of carotenoids triggers the cell wall remodelling.     

Comparison of manual vs. speech-based interaction with in-vehicle information systems

This study examined whether speech-based interfaces for different in-vehicle-information-systems (IVIS) reduce the distraction caused by these systems. For three frequently used systems (audio, telephone with name selection, navigation system with address entry and point of interest selection) speech, manual control and driving without IVIS (baseline) were compared. The Lane Change Task was used to assess driving performance. Additionally, gaze behavior and a subjective measure of distraction were analyzed. Speech interfaces improved driving performance, gaze behavior and subjective distraction for all systems with the exception of point-of-interest entry. However, these improvements were overall not strong enough to reach the baseline performance level. Only in easy segments of the driving task the performance level was comparable to baseline. Thus, speech-based IVIS have to be further developed to keep the cognitive complexity at an adequate level which does not disturb driving. However, looking at the benefits, speech control is a must for the car of the future.     

Presence of β-Lactamase-producing Enterobacterales and Salmonella Isolates in Marine Mammals

Marine mammals have been described as sentinels of the health of marine ecosystems. Therefore, the aim of this study was to investigate (i) the presence of extended-spectrum β-lactamase (ESBL)- and AmpC-producing Enterobacterales, which comprise several bacterial families important to the healthcare sector, as well as (ii) the presence of Salmonella in these coastal animals. The antimicrobial resistance pheno- and genotypes, as well as biocide susceptibility of Enterobacterales isolated from stranded marine mammals, were determined prior to their rehabilitation. All E. coli isolates (n = 27) were screened for virulence genes via DNA-based microarray, and twelve selected E. coli isolates were analyzed by whole-genome sequencing. Seventy-one percent of the Enterobacterales isolates exhibited a multidrug-resistant (MDR) pheno- and genotype. The gene bla_CMY (n = 51) was the predominant β-lactamase gene. In addition, bla_TEM-1 (n = 38), bla_SHV-33 (n = 8), bla_CTX-M-15 (n = 7), bla_OXA-1 (n = 7), bla_SHV-11 (n = 3), and bla_DHA-1 (n = 2) were detected. The most prevalent non-β-lactamase genes were sul2 (n = 38), strA (n = 34), strB (n = 34), and tet(A) (n = 34). Escherichia coli isolates belonging to the pandemic sequence types (STs) ST38, ST167, and ST648 were identified. Among Salmonella isolates (n = 18), S. Havana was the most prevalent serotype. The present study revealed a high prevalence of MDR bacteria and the presence of pandemic high-risk clones, both of which are indicators of anthropogenic antimicrobial pollution, in marine mammals.     

Über die Formänderung von Holz nach aufgehobener Quellungsbehinderung

Ohne Zusammenfassung

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On the strains of wood after termination of swelling restraint

     

Molecular-beam epitaxy growth and characterization of mid-infrared quantum cascade laser structures

The development of molecular-beam epitaxy (MBE) of GaAs/AlGaAs heterostructures, used for fabrication of ∼9 μm quantum cascade lasers (QCLs), is reported. The X-ray diffractometry (XRD) structural characterization, as an integral part of this process, is presented as well. Some conclusions, concerning the relationships between the used type of epitaxial technology and the necessity of special procedures of growth rate (V_gr) calibration, are reached. The influence of the structural features of the QCL active region on the electronic band structure is calculated, and consequently some predictions as to the device electrical properties are presented as well.