• Klíčová slova
• báze dat - systém DOS 5.0 - příručky,
• Publikační typ
• příručky MeSH

• Konspekt
• Programování. Software
• NLK Obory
• lékařská informatika

Podrobný popis datové struktury a algoritmů použitých v operačním systému UNIX verze V.

• MeSH
• informatika MeSH
• počítače MeSH
• software MeSH
• Publikační typ
• příručky MeSH

• Konspekt
• Programování. Software
• NLK Obory
• technika

The influence of maltose-modified poly(propylene imine) (PPI) dendrimers on dimyristoylphosphatidylcholine (DMPC) or dimyristoylphosphatidylcholine/dimyristoylphosphatidylglycerol (DMPC/DMPG) (3%) liposomes was studied. Fourth generation (G4) PPI dendrimers with primary amino surface groups were partially (open shell glycodendrimers - OS) or completely (dense shell glycodendrimers - DS) modified with maltose residues. As a model membrane, two types of 100nm diameter liposomes were used to observe differences in the interactions between neutral DMPC and negatively charged DMPC/DMPG bilayers. Interactions were studied using fluorescence spectroscopy to evaluate the membrane fluidity of both the hydrophobic and hydrophilic parts of the lipid bilayer and using differential scanning calorimetry to investigate thermodynamic parameter changes. Pulsed-filed gradient NMR experiments were carried out to evaluate common diffusion coefficient of DMPG and DS PPI in D2O when using below critical micelle concentration of DMPG. Both OS and DS PPI G4 dendrimers show interactions with liposomes. Neutral DS dendrimers exhibit stronger changes in membrane fluidity compared to OS dendrimers. The bilayer structure seems more rigid in the case of anionic DMPC/DMPG liposomes in comparison to pure and neutral DMPC liposomes. Generally, interactions of dendrimers with anionic DMPC/DMPG and neutral DMPC liposomes were at the same level. Higher concentrations of positively charged OS dendrimers induced the aggregation process with negatively charged liposomes. For all types of experiments, the presence of NaCl decreased the strength of the interactions between glycodendrimers and liposomes. Based on NMR diffusion experiments we suggest that apart from electrostatic interactions for OS PPI hydrogen bonds play a major role in maltose-modified PPI dendrimer interactions with anionic and neutral model membranes where a contact surface is needed for undergoing multiple H-bond interactions between maltose shell of glycodendrimers and surface membrane of liposome.

• MeSH
• dendrimery chemie   metabolismus   MeSH
• difenylhexatrien chemie   MeSH
• diferenciální skenovací kalorimetrie MeSH
• dimyristoylfosfatidylcholin chemie   metabolismus   MeSH
• fluidita membrány MeSH
• fluorescenční polarizace MeSH
• fosfatidylglyceroly chemie   metabolismus   MeSH
• hydrofobní a hydrofilní interakce MeSH
• lipidové dvojvrstvy chemie   metabolismus   MeSH
• liposomy chemie   metabolismus   MeSH
• magnetická rezonanční spektroskopie MeSH
• maltosa chemie   metabolismus   MeSH
• membránové lipidy chemie   metabolismus   MeSH
• polypropyleny chemie   metabolismus   MeSH
• statická elektřina MeSH
• vodíková vazba MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

ConspectusMagnetic resonance techniques represent a fundamental class of spectroscopic methods used in physics, chemistry, biology, and medicine. Electron paramagnetic resonance (EPR) is an extremely powerful technique for characterizing systems with an open-shell electronic nature, whereas nuclear magnetic resonance (NMR) has traditionally been used to investigate diamagnetic (closed-shell) systems. However, these two techniques are tightly connected by the electron-nucleus hyperfine interaction operating in paramagnetic (open-shell) systems. Hyperfine interaction of the nuclear spin with unpaired electron(s) induces large temperature-dependent shifts of nuclear resonance frequencies that are designated as hyperfine NMR shifts (δHF).Three fundamental physical mechanisms shape the total hyperfine interaction: Fermi-contact, paramagnetic spin-orbit, and spin-dipolar. The corresponding hyperfine NMR contributions can be interpreted in terms of through-bond and through-space effects. In this Account, we provide an elemental theory behind the hyperfine interaction and NMR shifts and describe recent progress in understanding the structural and electronic principles underlying individual hyperfine terms.The Fermi-contact (FC) mechanism reflects the propagation of electron-spin density throughout the molecule and is proportional to the spin density at the nuclear position. As the imbalance in spin density can be thought of as originating at the paramagnetic metal center and being propagated to the observed nucleus via chemical bonds, FC is an excellent indicator of the bond character. The paramagnetic spin-orbit (PSO) mechanism originates in the orbital current density generated by the spin-orbit coupling interaction at the metal center. The PSO mechanism of the ligand NMR shift then reflects the transmission of the spin polarization through bonds, similar to the FC mechanism, but it also makes a substantial through-space contribution in long-range situations. In contrast, the spin-dipolar (SD) mechanism is relatively unimportant at short-range with significant spin polarization on the spectator atom. The PSO and SD mechanisms combine at long-range to form the so-called pseudocontact shift, traditionally used as a structural and dynamics probe in paramagnetic NMR (pNMR). Note that the PSO and SD terms both contribute to the isotropic NMR shift only at the relativistic spin-orbit level of theory.We demonstrate the advantages of calculating and analyzing the NMR shifts at relativistic two- and four-component levels of theory and present analytical tools and approaches based on perturbation theory. We show that paramagnetic NMR effects can be interpreted by spin-delocalization and spin-polarization mechanisms related to chemical bond concepts of electron conjugation in π-space and hyperconjugation in σ-space in the framework of the molecular orbital (MO) theory. Further, we discuss the effects of environment (supramolecular interactions, solvent, and crystal packing) and demonstrate applications of hyperfine shifts in determining the structure of paramagnetic Ru(III) compounds and their supramolecular host-guest complexes with macrocycles.In conclusion, we provide a short overview of possible pNMR applications in the analysis of spectra and electronic structure and perspectives in this field for a general chemical audience.

• Publikační typ
• časopisecké články MeSH

The main task of the research is to acquire fundamental knowledge about the effect of polymer structure on the physicochemical properties of films. A novel meta-material that can be used in manufacturing sensor layers was developed as a model. At the first stage, poly(sodium 4-styrenesulfonate) (PNaSS) cross-linked microspheres are synthesized (which are based on strong polyelectrolytes containing sulfo groups in each monomer unit), and at the second stage, PNaSS@PEDOT microspheres are formed. The poly(3,4-ethylenedioxythiophene) (PEDOT) shell was obtained by the acid-assisted self-polymerization of the monomer; this process is biologically safe and thus suitable for biomedical applications. The suitability of electrochemical impedance spectroscopy for E. coli detection was tested; it was revealed that the attached bacterial wall was destroyed upon application of constant oxidation potential (higher than 0.5 V), which makes the PNaSS@PEDOT microsphere particles promising materials for the development of antifouling coatings. Furthermore, under open-circuit conditions, the walls of E. coli bacteria were not destroyed, which opens up the possibility of employing such meta-materials as sensor films. Scanning electron microscopy, X-ray photoelectron spectroscopy, water contact angle, and wide-angle X-ray diffraction methods were applied in order to characterize the PNaSS@PEDOT films.

• MeSH
• bicyklické sloučeniny heterocyklické chemie   MeSH
• Escherichia coli * MeSH
• mikrosféry MeSH
• polymery * chemie   MeSH
• Publikační typ
• časopisecké články MeSH

INTRODUCTION: Remote navigation systems represent a novel strategy for catheter ablation of atrial fibrillation (AF). The goal of this study is to describe a single-center experience with the electromechanical robotic system (Sensei, Hansen Medical) in treatment of patients with paroxysmal AF. METHODS: Out of 200 patients who underwent robotically guided ablation for AF between 2007 and 2009 at our institute, 100 patients (29 women, age 56.5 ± 10 years) had paroxysmal AF refractory to antiarrhythmic drugs. Electroanatomic mapping using NavX system (St. Jude Medical) provided anatomical shell for subsequent circumferential ablation with robotic catheter (Artisan) loaded with a 3.5-mm, open-irrigation, cooled-tip ablation catheter. RESULTS: A mean of 69 radiofrequency current applications (duration 2082 ± 812 seconds) were delivered to achieve circumferential electrical isolation of pulmonary venous antra. Total procedural time reached 222 ± 54 minutes. The mean fluoroscopic time was 11.9 ± 7.8 minutes. There were no major procedure-related complications. After a median follow-up of 15 months (range 3-28 months), 63% of the patients were free from any atrial arrhythmias ≥ 30 seconds after the single procedure. Success rate increased to 86% after 1.2 procedures. Multivariate analysis revealed that only predictor of recurrent AF/AT was shorter overall procedural time (207 ± 36 vs 236 ± 64 minutes in patients with and without recurrences, respectively, P = 0.0068). CONCLUSIONS: This study demonstrates feasibility and safety of robotic navigation in catheter ablation for paroxysmal AF. Midterm follow-up documents success rate comparable to other technologies and potential for improvement in more extensive ablation along the ridges with thicker myocardium.

• MeSH
• chirurgie s pomocí počítače MeSH
• fibrilace síní epidemiologie   chirurgie   MeSH
• hodnocení rizik MeSH
• katetrizační ablace statistika a číselné údaje   MeSH
• komorbidita MeSH
• lidé středního věku MeSH
• lidé MeSH
• pooperační komplikace epidemiologie   prevence a kontrola   MeSH
• prognóza MeSH
• recidiva MeSH
• rizikové faktory MeSH
• robotika statistika a číselné údaje   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH

Structural properties of plasmenyl-glycerophospholipids (plasmalogens) have been scarcely studied for plasmalogens with long polyunsaturated fatty acid (PUFA) chains, despite of their significance for the organization and functions of the cellular membranes. Elaboration of supramolecular assemblies involving PUFA-chain plasmalogens in nanostructured mixtures with lyotropic lipids may accelerate the development of nanomedicines for certain severe pathologies (e.g., peroxisomal disorders, cardiometabolic impairments, and neurodegenerative Alzheimer's and Parkinson's diseases). Here, we investigate the spontaneous self-assembly of bioinspired, custom-produced docosapentaenoyl (DPA) plasmenyl (ether) and ester phospholipids in aqueous environment (pH 7) by synchrotron small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM). A coexistence of a liquid crystalline primitive cubic Im3m phase and an inverted hexagonal (HII) phase is observed for the DPA-ethanolamine plasmalogen (C16:1p-22:5n6 PE) derivative. A double-diamond cubic Pn3m phase is formed in mixed assemblies of the phosphoethanolamine plasmalogen (C16:1p-22:5n6 PE) and monoolein (MO), whereas a coexistence of cubic and lamellar liquid crystalline phases is established for the DPA-plasmenyl phosphocholine (C16:1p-22:5n6 PC)/MO mixture at ambient temperature. The DPA-diacyl phosphoinositol (22:5n6-22:5n6 PI) ester lipid displays a propensity for a lamellar phase formation. Double membrane vesicles and multilamellar onion topologies with inhomogeneous distribution of interfacial curvature are formed upon incorporation of the phosphoethanolamine plasmalogen (C16:1p-22:5n6 PE) into dioleoylphosphocholine (DOPC) bilayers. Nanoparticulate formulations of plasmalogen-loaded cubosomes, hexosomes, and various multiphase cubosome- and hexosome-derived architectures and mixed type nano-objects (e.g., oil droplet-embedding vesicles or core-shell particles with soft corona) are produced with PUFA-chain phospholipids and lipophilic antioxidant-containing membrane compositions that are characterized by synchrotron SAXS and cryo-TEM imaging. The obtained multiphase nanostructures reflect the changes in the membrane curvature induced by the inclusion of DPA-based PE and PC plasmalogens, as well as DPA-PI ester derivative, and open new opportunities for exploration of these bioinspired nanoassemblies.

• Publikační typ
• časopisecké články MeSH

Carefully controlled gas exchange across the eggshell is essential for the development of the avian embryo. Water vapour conductance (G(H2O)) across the shell, typically measured as mass loss during incubation, has been demonstrated to optimally ensure the healthy development of the embryo while avoiding desiccation. Accordingly, eggs exposed to sub-optimal gas exchange have reduced hatching success. We tested the association between eggshell G(H2O) and putative life-history correlates of adult birds, ecological nest parameters and physical characteristics of the egg itself to investigate how variation in G(H2O) has evolved to maintain optimal water loss across a diverse set of nest environments. We measured gas exchange through eggshell fragments in 151 British breeding bird species and fitted phylogenetically controlled, general linear models to test the relationship between G(H2O) and potential predictor parameters of each species. Of our 17 life-history traits, only two were retained in the final model: wet-incubating parent and nest type. Eggs of species where the parent habitually returned to the nest with wet plumage had significantly higher G(H2O) than those of parents that returned to the nest with dry plumage. Eggs of species nesting in ground burrows, cliffs and arboreal cups had significantly higher G(H2O) than those of species nesting on the ground in open nests or cups, in tree cavities and in shallow arboreal nests. Phylogenetic signal (measured as Pagel's λ) was intermediate in magnitude, suggesting that differences observed in the G(H2O) are dependent upon a combination of shared ancestry and species-specific life history and ecological traits. Although these data are correlational by nature, they are consistent with the hypothesis that parents constrained to return to the nest with wet plumage will increase the humidity of the nest environment, and the eggs of these species have evolved a higher G(H2O) to overcome this constraint and still achieve optimal water loss during incubation. We also suggest that eggs laid in cup nests and burrows may require a higher G(H2O) to overcome the increased humidity as a result from the confined nest microclimate lacking air movements through the nest. Taken together, these comparative data imply that species-specific levels of gas exchange across avian eggshells are variable and evolve in response to ecological and physical variation resulting from parental and nesting behaviours.

• MeSH
• druhová specificita MeSH
• fylogeneze MeSH
• hnízdění fyziologie   MeSH
• ptáci genetika   fyziologie   MeSH
• vaječná skořápka fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• molekulární biologie MeSH
• proteiny MeSH
• Publikační typ
• monografie MeSH

• Konspekt
• Biochemie. Molekulární biologie. Biofyzika
• NLK Obory
• biochemie
• molekulární biologie, molekulární medicína

• MeSH
• software MeSH
• Publikační typ
• příručky MeSH

• Konspekt
• Počítačová věda. Výpočetní technika. Informační technologie
• NLK Obory
• technika