time-resolved X-ray diffraction
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X-ray structure analysis results have been widely used in the pharmaceutical research, development and control, especially for mapping polymorphism, to determine the chirality of active substances, in the pharmaceutical documentation and patent policy for many years. The greatest progress in X-ray diffraction techniques has been made in improving the quality of the poor material for successful data collection (magnetically oriented microcrystal arrays, serial snapshot crystallography). Prospects of the pharmaceutical application of X-ray crystallography lie in the acceleration of data collection, time-resolved structural studies obtained from the material of pharmaceutical batches without modification, and, in addition to that, in solving structures of semi-solid and amorphous phases and monitoring structural changes in drug formulations.
- MeSH
- difrakce rentgenového záření MeSH
- duševní vlastnictví MeSH
- farmaceutická technologie MeSH
- krystalografie rentgenová * metody přístrojové vybavení využití MeSH
- léčivé přípravky * analýza MeSH
- spektrální analýza metody přístrojové vybavení využití MeSH
- stereoizomerie MeSH
- Publikační typ
- práce podpořená grantem MeSH
Short illumination wavelength allows an extension of the diffraction limit toward nanometer scale; thus, improving spatial resolution in optical systems. Soft X-ray (SXR) radiation, from "water window" spectral range, λ=2.3-4.4 nm wavelength, which is particularly suitable for biological imaging due to natural optical contrast provides better spatial resolution than one obtained with visible light microscopes. The high contrast in the "water window" is obtained because of selective radiation absorption by carbon and water, which are constituents of the biological samples. The development of SXR microscopes permits the visualization of features on the nanometer scale, but often with a tradeoff, which can be seen between the exposure time and the size and complexity of the microscopes. Thus, herein, we present a desk-top system, which overcomes the already mentioned limitations and is capable of resolving 60 nm features with very short exposure time. Even though the system is in its initial stage of development, we present different applications of the system for biology and nanotechnology. Construction of the microscope with recently acquired images of various samples will be presented and discussed. Such a high resolution imaging system represents an interesting solution for biomedical, material science, and nanotechnology applications.
- MeSH
- biologie metody MeSH
- fibroblasty cytologie MeSH
- karcinom patologie MeSH
- mikroskopie přístrojové vybavení metody MeSH
- myši MeSH
- nádory tračníku patologie MeSH
- nanotechnologie metody MeSH
- počítačové zpracování obrazu MeSH
- rentgenové záření MeSH
- uhlík MeSH
- voda MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared on transparent membranes which are very fragile and difficult to manipulate. We present processes for the fabrication of samples with magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for Lorentz transmission electron microscopy and magnetic transmission x-ray microscopy studies. The samples are prepared on silicon nitride membranes and the fabrication consists of a spin coating, UV and electron-beam lithography, the chemical development of the resist, and the evaporation of the magnetic material followed by a lift-off process forming the final magnetic structures. The samples for the Lorentz transmission electron microscopy consist of magnetic nanodiscs prepared in a single lithography step. The samples for the magnetic x-ray transmission microscopy are used for time-resolved magnetization dynamic experiments, and magnetic nanodiscs are placed on a waveguide which is used for the generation of repeatable magnetic field pulses by passing an electric current through the waveguide. The waveguide is created in an extra lithography step.
Apoptosis signal-regulating kinase 1 (ASK1, also known as MAP3K5), a member of the mitogen-activated protein kinase kinase kinase (MAP3K) family, regulates diverse physiological processes. The activity of ASK1 is triggered by various stress stimuli and is involved in the pathogenesis of cancer, neurodegeneration, inflammation, and diabetes. ASK1 forms a high molecular mass complex whose activity is, under non-stress conditions, suppressed through interaction with thioredoxin and the scaffolding protein 14-3-3. The 14-3-3 protein binds to the phosphorylated Ser-966 motif downstream of the ASK1 kinase domain. The role of 14-3-3 in the inhibition of ASK1 has yet to be elucidated. In this study we performed structural analysis of the complex between the ASK1 kinase domain phosphorylated at Ser-966 (pASK1-CD) and the 14-3-3ζ protein. Small angle x-ray scattering (SAXS) measurements and chemical cross-linking revealed that the pASK1-CD·14-3-3ζ complex is dynamic and conformationally heterogeneous. In addition, structural analysis coupled with the results of phosphorus NMR and time-resolved tryptophan fluorescence measurements suggest that 14-3-3ζ interacts with the kinase domain of ASK1 in close proximity to its active site, thus indicating this interaction might block its accessibility and/or affect its conformation.
- MeSH
- difrakce rentgenového záření MeSH
- fosforylace MeSH
- katalytická doména MeSH
- lidé MeSH
- maloúhlový rozptyl MeSH
- MAP kinasa-kinasa-kinasa 5 antagonisté a inhibitory chemie genetika metabolismus MeSH
- nukleární magnetická rezonance biomolekulární MeSH
- proteiny 14-3-3 chemie genetika metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
A highly prospective drug for the X-ray induced photodynamic therapy (PDTX), LuAG:Pr3+@SiO2-PpIX nanocomposite, was successfully prepared by a three step process: photo-induced precipitation of the Lu3Al5O12:Pr3+(LuAG:Pr3+) core, sol-gel technique for amorphous silica coating, and a biofunctionalization by attaching the protoporphyrin IX (PpIX) molecules. The synthesis procedure provides three-layer nanocomposite with uniform shells covering an intensely luminescent core. Room temperature radioluminescence (RT RL) spectra as well as photoluminescence (RT PL) steady-state and time resolved spectra of the material confirm the non-radiative energy transfer from the core Pr3+ions to the PpIX outer layer. First, excitation of Pr3+ions results in the red luminescence of PpIX. Second, the decay measurements exhibit clear evidence of mentioned non-radiative energy transfer (ET). The singlet oxygen generation in the system was demonstrated by the 3'-(p-aminophenyl) fluorescein (APF) chemical probe sensitive to the singlet oxygen presence. The RT PL spectra of an X-ray irradiated material with the APF probe manifest the formation of singlet oxygen due to which enhanced luminescence around 530 nm is observed. Quenching studies, using NaN3as an1O2inhibitor, also confirm the presence of1O2in the system and rule out the parasitic reaction with OH radicals. To summarize, presented features of LuAG:Pr3+@SiO2-PpIX nanocomposite indicate its considerable potential for PDTX application.
High concentrations of airborne asbestos in the ambient air are still a serious problem of air quality in numerous localities around the world. Since 2002, elevated concentrations of asbestos minerals of unknown origin have been detected in the ambient air of Pilsen, Czech Republic. To determine the asbestos fibre sources in this urban air, a systematic study was conducted. First, 14 bulk dust samples were collected in Pilsen at nine localities, and 6 bulk samples of construction aggregates for gravel production were collected in a quarry in the Pilsen-Litice district. The quarry is the largest quarry in the Pilsen region and the closest quarry to the built-up urban area. X-ray diffraction of the asbestos minerals revealed that monoclinic amphibole (MA, namely actinolite based on subsequent SEM-EDX analysis) in the bulk samples accounted for < 1-33% of the mass and that the highest values were found in the bulk dust samples from the railway platform of the Pilsen main railway station. Simultaneously, 24-h samples of airborne particulate matter (PM) at three localities in Pilsen were collected. Actinolite was identified in 40% of the PM samples. The relationship between the meteorology and presence of actinolite in the 24 PM10 samples was not proven, probably due to the long sampling integration time. Therefore, highly time-and-size-resolved PM sampling was performed. Second, sampling of size-segregated aerosols and measurements of the wind speed (WS), wind direction (WD), precipitation (P) and hourly PM10, PM2.5 and PM1 were conducted in a suburban locality near the quarry in two monthly highly time-resolved periods (30, 60, 120 min). Three/eight PM size fractions were sampled by a Davis Rotating-drum Uniform-size-cut Monitor (3/8DRUM) and analysed for the presences of asbestos fibres by scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDX). Asbestos fibre detection in highly time-resolved PM samples and current WD and WS determination allows the apportionment directionality of asbestos fibre sources. The number of critical actinolite asbestos fibres (length ≥ 5 μm and width < 3 μm, 3:1) increased with the PM1-10/PM10 and PM2.5-10/PM10 ratios, WS > 2 m s-1 and precipitation < 1 mm. Additionally, the number of critical actinolite asbestos fibres was not related to a specific WD. Therefore, we conclude that the sources of airborne critical actinolite asbestos fibres in Pilsen's urban area are omnipresent. Frequent use of construction aggregates and gravel from the metamorphic spilite quarries in the Pilsen region and in many localities around the urban area is a plausible explanation for the omnipresence of the critical actinolite asbestos fibres concentration in Pilsen's ambient air. Mitigation strategies to reduce the concentrations of critical actinolite asbestos fibres must be developed. Continuous monitoring and performing SEM-EDX analysis of highly time-and-size-resolved PM samples, correlated with fast changing WS and WD, seems to be a strong tool for efficiently controlling the mitigation strategies of critical actinolite asbestos fibres.
- MeSH
- aerosoly analýza MeSH
- azbest chemie MeSH
- látky znečišťující vzduch analýza MeSH
- mikroskopie elektronová rastrovací MeSH
- monitorování životního prostředí metody MeSH
- pevné částice chemie MeSH
- prach analýza MeSH
- velikost částic MeSH
- znečištění ovzduší MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
... Chemistry Is Based on Carbon Compounds 44 -- Cells Use Four Basic Types of Small Molecules 45 ix -- X ... ... Patterns -- They Create 154 -- Image Reconstruction Techniques Based on -- Diffraction Can Be Used to ... ... Extract Additional -- Information from Electron Micrographs 157 -- X-ray Diffraction Reveals the Three-dimensional ... ... During the S Phase -- Replication Times During the S Phase Are Correlated with Interphase Chromatin ... ... Structure -- How Is the Timing of DNA Replication Controlled? ...
xxxix, 1146 s. : il., tab. ; 28 cm
- MeSH
- biologie buňky MeSH
- molekulární biologie MeSH
- Publikační typ
- monografie MeSH
- Konspekt
- Biochemie. Molekulární biologie. Biofyzika
- NLK Obory
- biologie
- cytologie, klinická cytologie
... Fewer Than 500 Genes -- OF GENOMES AND THE TREE OF LIFE e lowered by a Variety of Free-Energy Sources r x ... ... Sequences of Two Species Differ in Proportion to re ength of Time Since They Have Separately Evolved ... ... One -- Part of the Cell Cycle 258 -- Different Regions on the Same Chromosome Replicate at Distinct Times ... ... Can Be Selectively Disrupted With Small -- Molecules 459 -- Protein Structure Can Be Determined Using X-Ray ... ... Diffraction 460 -- NMR Can Be Used to Determine Protein Structure in Solution 461 -- Protein Sequence ...
Sixth edition xxxiv, 1430 stran v různém stránkování : ilustrace (převážně barevné) ; 29 cm
- Konspekt
- Biochemie. Molekulární biologie. Biofyzika
- NLK Obory
- molekulární biologie, molekulární medicína
- NLK Publikační typ
- učebnice vysokých škol
