ilustr., grafy, sch.
- MeSH
- Amphetamines analysis MeSH
- Urinalysis * methods MeSH
- Solid Phase Extraction MeSH
- Fluorescence Polarization Immunoassay MeSH
- Mass Spectrometry MeSH
- Designer Drugs * analysis poisoning MeSH
- Poisoning * diagnosis MeSH
- Gas Chromatography-Mass Spectrometry MeSH
- Chromatography, High Pressure Liquid MeSH
Plants adjust their growth according to gravity. Gravitropism involves gravity perception, signal transduction, and asymmetric growth response, with organ bending as a consequence [1]. Asymmetric growth results from the asymmetric distribution of the plant-specific signaling molecule auxin [2] that is generated by lateral transport, mediated in the hypocotyl predominantly by the auxin transporter PIN-FORMED3 (PIN3) [3-5]. Gravity stimulation polarizes PIN3 to the bottom sides of endodermal cells, correlating with increased auxin accumulation in adjacent tissues at the lower side of the stimulated organ, where auxin induces cell elongation and, hence, organ bending. A curvature response allows the hypocotyl to resume straight growth at a defined angle [6], implying that at some point auxin symmetry is restored to prevent overbending. Here, we present initial insights into cellular and molecular mechanisms that lead to the termination of the tropic response. We identified an auxin feedback on PIN3 polarization as underlying mechanism that restores symmetry of the PIN3-dependent auxin flow. Thus, two mechanistically distinct PIN3 polarization events redirect auxin fluxes at different time points of the gravity response: first, gravity-mediated redirection of PIN3-mediated auxin flow toward the lower hypocotyl side, where auxin gradually accumulates and promotes growth, and later PIN3 polarization to the opposite cell side, depleting this auxin maximum to end the bending. Accordingly, genetic or pharmacological interference with the late PIN3 polarization prevents termination of the response and leads to hypocotyl overbending. This observation reveals a role of auxin feedback on PIN polarity in the termination of the tropic response.
- MeSH
- Arabidopsis genetics growth & development physiology MeSH
- Gravitropism * MeSH
- Indoleacetic Acids metabolism MeSH
- Gravity Sensing * MeSH
- Arabidopsis Proteins genetics metabolism MeSH
- Plant Growth Regulators metabolism MeSH
- Plant Shoots growth & development MeSH
- Feedback, Physiological MeSH
- Publication type
- Journal Article MeSH
Cíl: V rámci procesu in vitro fertilizace (IVF) zhodnotit možnost použití stavu meiotického vřeténka jako indikátoru zralosti oocytů za účelem optimalizace načasování vitrifikace. Pacienti a metody: V rámci léčby neplodnosti 38leté ženy a 43letého muže metodou IVF-ICSI (intracytoplazmatická injekce spermie) byla zobrazena dělicí vřeténka jako markery zralosti oocytů před jejich vitrifikací z důvodu azoospermie u partnera. Oocyty, u nichž byl úhel mezi polárním tělískem a meiotickým vřeténkem ≤ 30°, případně měly špatně viditelné meiotické vřeténko, byly vitrifikovány 4 hod po vyhodnocení meiotického vřeténka (8 hod po odběru oocytů). Standardně jsou oocyty vitrifikovány 6 hod po odběru oocytů. Výsledky: Delší doba inkubace oocytů pacientky umožnila, aby oocyty před vitrifikací plně dozrály (do fáze MII) a po rozmrazení byly připraveny pro oplodnění. U partnera pacientky byly následně získány vitální spermie po léčbě tamoxifenem, oocyty byly rozmrazeny a oplodněny získanými spermiemi, s následným embryotransferem a porodem zdravého dítěte v termínu. Závěr: Meiotické vřeténko je možné použít jako marker plné zralosti u oocytů před jejich vitrifikací u starších žen. Po rozmrazení byly oocyty zralé a připravené pro oplodnění metodou ICSI.
Aim: Within the in vitro fertilization (IVF) process, to evaluate the possibility of using the state of the meiotic spindle of oocytes as an indicator of maturity in order to optimize the timing of vitrification. Patients and methods: In the presented report, the cause of couple infertility was a combination of a 38-year-old female and 43-year-old male with azoospermia, which was an indication for oocyte vitrification. Oocyte polar bodies and optically birefringent meiotic spindles were visualized by polarized light microscopy and their states and relative positions were used as indicators of oocyte maturation, i.e. readiness for vitrification. Oocytes which had an angle between the polar body and meiotic spindle a ≤ 30° or had a poorly visible meiotic spindle were vitrified 4 hours post-meiotic spindle evaluation (8 hours after ovum pick-up). Results: After thawing, oocytes were fully maturated and prepared for intracytoplasmic sperm injection (ICSI). Following treatment with tamoxifen, vital sperm were retrieved from the patient’s partner, the oocytes were thawed and fertilized with the obtained sperm, with subsequent embryo transfer and delivery of a healthy baby at term. Conclusion: The meiotic spindle can be used as an oocyte maturation pointer in older women. After thawing, the oocytes were fully matured and ready for fertilization by ICSI.
- MeSH
- Spindle Apparatus * ultrastructure MeSH
- Biomarkers * analysis MeSH
- Adult MeSH
- Fertilization in Vitro * methods MeSH
- Infertility therapy MeSH
- Humans MeSH
- Oocytes pathology growth & development ultrastructure MeSH
- Polar Bodies MeSH
- Tamoxifen therapeutic use MeSH
- Vitrification MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Case Reports MeSH
PURPOSE: The tear film lipid layer (TFLL) covers the tear film, stabilizing it and providing a protective barrier against the environment. The TFLL is divided into polar and non-polar sublayers, but the interplay between lipid classes in these sublayers and the structure-function relationship of the TFLL remains poorly characterized. This study aims to provide insight into TFLL function by elucidating the interactions between polar and non-polar TFLL lipids at the molecular level. METHODS: Mixed films of polar O-acyl-ω-hydroxy fatty acids (OAHFA) or phospholipids and non-polar cholesteryl esters (CE) were used as a model of the TFLL. The organization of the films was studied by using a combination of Brewster angle and fluorescence microscopy in a Langmuir trough system. In addition, the evaporation resistance of the lipid films was evaluated. RESULTS: Phospholipids and OAHFAs induced the formation of a stable multilamellar CE film. The formation of this film was driven by the interdigitation of acyl chains between the monolayer of polar lipids and the CE multilayer lamellae. Surprisingly, the multilayer structure was destabilized by both low and high concentrations of polar lipids. In addition, the CE multilayer was no more effective in resisting the evaporation of water than a polar lipid monolayer. CONCLUSIONS: Formation of multilamellar films by major tear film lipids suggest that the TFLL may have a similar structure. Moreover, in contrast to the current understanding, polar TFLL lipids may not mainly act by stabilizing the non-polar TFLL sublayer, but through a direct evaporation resistant effect.
- MeSH
- Cholesterol Esters MeSH
- Lipids MeSH
- Fatty Acids MeSH
- Tears * MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Mesoporous material SBA-15 was functionalized with different polar and nonpolar groups: 3-aminopropyl, (SBA-15-NH2), 3-isocyanatopropyl (SBA-15-NCO), 3-mercaptopropyl (SBA-15-SH), methyl (SBA-15-CH3) and phenyl (SBA-15-Ph). The resulting surface grafted materials were investigated as matrices for controlled drug delivery. Anticancer agent, pemetrexed (disodium pemetrexed heptahydrate) was selected as a model drug and loaded in the unmodified and functionalized SBA-15 materials. Materials were characterized by elemental analysis, infrared spectroscopy, transmission electron microscopy, nitrogen adsorption/desorption analysis, small angle X-ray scattering, powder X-ray diffraction, solid state NMR spectroscopy and thermogravimetry. It was shown that surface modification has an impact on both encapsulated drug amount and release properties. Release experiments were performed into two media with different pH: simulated body fluid (pH = 7.4) and simulated gastric fluid (pH = 2). In general, the effect of pH was reflected by the lower release of pemetrexed under acidic conditions (pH = 2) compared to slightly alkaline saline environment (pH = 7.4). The release rate of pemetrexed from propylamine-, propylisocyanate- and phenyl-modified SBA-15 was found to be effectively controlled by intermolecular interactions as compared to that from pure SBA-15, SBA-15-SH, and SBA-15-CH3, that evidenced a steady and similar release. The highest release was observed for methyl-functionalized material whose hydrophobic surface accelerates the pemetrexed release. The data obtained from release studies were fitted using various kinetic models to determine the pemetrexed release mechanism and its release rate. The best correlations were found for Korsmeyer-Peppas and Higuchi models. Moreover, the theoretical three-parameter model for drug release kinetic was applied to calculate the strength of drug-support interactions. The in vitro cell study was performed on SKBR3 cancer cells and obtained results demonstrated that the modification of the mesoporous silica material by grafted polar/nonpolar groups may significantly affect the compatibility of this material with cells, drug release from this material and subsequent biological activity of PEM.
- MeSH
- Hydrogen-Ion Concentration MeSH
- Delayed-Action Preparations chemistry pharmacokinetics pharmacology MeSH
- Humans MeSH
- Cell Line, Tumor MeSH
- Neoplasms drug therapy metabolism pathology MeSH
- Silicon Dioxide * chemistry pharmacokinetics pharmacology MeSH
- Pemetrexed * chemistry pharmacokinetics pharmacology MeSH
- Surface Properties MeSH
- Antineoplastic Agents * chemistry pharmacokinetics pharmacology MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Recent advances in polarizable force fields have revealed that major reparameterization is necessary when the polarization energy is treated explicitly. This study is focused on the torsional parameters, which are crucial for the accurate description of conformational equilibria in biomolecules. In particular, attention is paid to the influence of polarization on the (i) transferability of dihedral terms between molecules, (ii) transferability between different environments, and (iii) additivity of dihedral energies. To this end, three polarizable force fields based on the induced point dipole model designed for use in AMBER are tested, including two recent ff02 reparameterizations. Attention is paid to the contributions due to short range interactions (1-2, 1-3, and 1-4) within the four atoms defining the dihedral angle. The results show that when short range 1-2 and 1-3 polarization interactions are omitted, as for instance in ff02, the 1-4 polarization contribution is rather small and unlikely to improve the description of the torsional energy. Conversely, when screened 1-2 and 1-3 interactions are included, the polarization contribution is sizeable and shows potential to improve the transferability of parameters between different molecules and environments as well as the additivity of dihedral terms. However, to reproduce intramolecular polarization effects accurately, further fine-tuning of the short range damping of polarization is necessary.
of light 6 -- Interference and coherence .6 -- Applications of interference and coherence .7 -- Polarization .8 -- Applications of polarization .10 -- Diffraction .10 -- Scattering 12 -- Reflection 12 -- Transmission 49 -- First approximation: ignore image quality .50 -- The paraxial approximation 50 -- The small-angle principle, and the lensmeter 75 -- Afocal systems 77 -- Ophthalmic prisms 78 -- Plane parallel plate 79 -- Angle
xii, 304 stran : ilustrace ; 25 cm
The textbook focuses on basic and clinical science, ophthalmology, optics, refraction and contact lenses. Intended for professional public and for university students.
- MeSH
- Clinical Medicine MeSH
- Contact Lenses MeSH
- Ophthalmology MeSH
- Optics and Photonics MeSH
- Refraction, Ocular MeSH
- Science MeSH
- Conspectus
- Ortopedie. Chirurgie. Oftalmologie
- Učební osnovy. Vyučovací předměty. Učebnice
- NML Fields
- oftalmologie
- věda a výzkum
- NML Publication type
- učebnice vysokých škol
light . 6 -- Interference and coherence . 6 -- Applications of interference and coherence 7 -- Polarization 8 -- Applications,.of polarization . 10 -- Diffraction 10 -- Scattering 12 -- Reflection . 12 -- Transmission -- First approximation: ignore image quality 50 -- V -- The paraxial approximation 50 -- The small-angle and the lensmeter 75 -- Afocal systems . 77 -- Ophthalmic prisms . 78 -- Plane parallel plate 79 -- Angle
xii, 304 stran : ilustrace ; 25 cm
The textbook focuses on basic and clinical science, ophthalmology, optics, refraction, and contact lenses. Intended for professional public and for university students.
- MeSH
- Clinical Medicine MeSH
- Contact Lenses MeSH
- Ophthalmology MeSH
- Optics and Photonics MeSH
- Refraction, Ocular MeSH
- Science MeSH
- Conspectus
- Učební osnovy. Vyučovací předměty. Učebnice
- Ortopedie. Chirurgie. Oftalmologie
- NML Fields
- oftalmologie
- věda a výzkum
- NML Publication type
- učebnice vysokých škol
Rotating Dipoles and Angle-Averaged Potentials 84 -- 4.11. Interactions Involving the Polarization of Molecules 91 -- 5.1. Other Polarization Mechanisms and the Effects -- of Polarization on Electrostatic Interactions 94 -- Unification of Polarization Interactions 99 -- 5.8. Contact Angle Hysteresis 439 -- 17.7.
Third edition xxx, 674 stran : 24 cm il. ;
- MeSH
- Chemistry, Physical MeSH
- Publication type
- Monograph MeSH
- Conspectus
- Fyzikální chemie
- NML Fields
- chemie, klinická chemie
The complex index of refraction in the spectral range of 0.74 to 4.5 eV is studied by variable-angle spectroscopic ellipsometry in ferroelectric K0.5Na0.5NbO3 films. The 20-nm-thick cube-on-cube-type epitaxial films are grown on SrTiO3(001) and DyScO3(011) single-crystal substrates. The films are transparent and exhibit a significant difference between refractive indices Δn = 0.5 at photon energies below 3 eV. The energies of optical transitions are in the range of 3.15-4.30 eV and differ by 0.2-0.3 eV in these films. The observed behavior is discussed in terms of lattice strain and strain-induced ferroelectric polarization in epitaxial perovskite oxide films.
