Disasters involving radioactive materials are one of the most dangerous accidents a living organism can be exposed to. Individuals and first responders are in risk during accidents or interventions, due to radioactive debris impact, due to the use of depleted uranium ammunition or a malevolent act against individuals. Moreover, radioactive contamination of wounds causes internal exposure in the body and standard decontamination procedures cannot be applied. In order to deal with such situations, we are developing a measurement system consisting of a robotic arm, an array of various detectors and a corresponding methodology, which allows quantifying timely the spatial distribution of contamination and the radiation dose for the adequate medical response. The aim of this publication is to the present current status of the development of the described apparatus.

• MeSH
• lidé MeSH
• radiometrie * MeSH
• uran * MeSH
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• lidé MeSH
• Publikační typ
• časopisecké články 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
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• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

In this article, we describe the preparation and cytotoxic properties of a small focused library of lupane and 18α-oleanane triterpenoids that contain a combination of two structural motifs known to enhance the biological activities. First, we introduced two fluorine atoms to position 2 of the skeleton. Second, we synthesized a set of hemiester prodrugs, which were intended to increase the solubility and activity. Starting from betulin, we obtained two hydroxyketones (derivatives of dihydrobetulinic acid and allobetulin) and their fluorination using DAST provided 2,2-difluoro-3-oxo-compounds as the main products. Then the 3-oxo group in each derivative was reduced by NaBH4 to obtain 3β-hydroxy compounds suitable for modifying by various hemiesters. We prepared 21 compounds, 11 of them new, their cytotoxicity was tested on T lymphoblastic leukemia CCRF-CEM cells first and the most active derivatives were selected for screening on another six tumor and two non-tumor cell lines. All of them showed selectivity against cancer lines with therapeutic index between 2 and 8. All hemiesters had activity in the same range as the free hydroxyl derivatives and they would be suitable prodrugs for future in vivo experiments. Interestingly, all hemiesters of 2,2-difluorodihydrobetulonic acid had higher activity against p53 knock-out p53-/- cancer cell line than against the non-mutated analog. In active derivatives, the cell cycle was analyzed by flow cytometry and several compounds slowed down cell cycle progression through G0/G1 or S-phase.

• MeSH
• antitumorózní látky fytogenní chemická syntéza   chemie   farmakologie   MeSH
• apoptóza účinky léků   MeSH
• buněčný cyklus účinky léků   MeSH
• fibroblasty účinky léků   MeSH
• fluorované uhlovodíky chemická syntéza   chemie   farmakologie   MeSH
• léky antitumorózní - screeningové testy MeSH
• lidé MeSH
• molekulární konformace MeSH
• nádorové buňky kultivované MeSH
• proliferace buněk účinky léků   MeSH
• triterpeny chemie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
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• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH