x
x
- MeSH
- adenosin aplikace a dávkování MeSH
- frakční průtoková rezerva myokardu účinky léků MeSH
- kardiologické zobrazovací techniky metody přístrojové vybavení MeSH
- koronární angiografie metody přístrojové vybavení MeSH
- lidé MeSH
- nemoci koronárních tepen * diagnostické zobrazování MeSH
- optická koherentní tomografie metody MeSH
- spektrofotometrie infračervená metody přístrojové vybavení MeSH
- srdeční katetrizace metody MeSH
- stupeň závažnosti nemoci MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
Stereospecific nucleation of mesoporous hybrid microspheres composed of CaCO3 and carrageenan was appended to one side of bacterial cellulose membrane synthesized in static cultures of Gluconacetobacter hansenii to develop an implantable drug delivery device. The synthesis of the hybrid microparticles proceeds by self-assembly mechanism in the presence of calcium and contains tailorable amounts of doxorubicin. However, in the absence of the particles, doxorubicin was distributed along the BC film, but without control release of drug. Infrared spectroscopy, confocal and scanning electron microscopies analyses demonstrate that the doxorubicin is entrapped inside the hybrid particles with approximately 80% drug loading compared to the 11% obtained for native bacterial cellulose. Doxorubicin content in the hybrid particles can be increased by a factor of 10 (from 258.6 to 2586.3 nmol ml−1), and also by the quantities of particles regulated by the CaCO3–carrageenan content and the physicochemical microenvironment. The hybrid BC system can be considered as smart device since the kinetic release of doxorubicin from the hybrid cellulose system rise from 1.50 to 2.75 μg/membrane/day when the pH decreases from 7.4 to 5.8 at 37 °C, a pathologic simulated environment. The hybrid microparticle system can be potentially used as an implantable drug delivery system for personalized oncological therapies.
- MeSH
- bakteriální polysacharidy biosyntéza farmakologie metabolismus MeSH
- biomedicínský výzkum metody trendy MeSH
- celulosa * biosyntéza farmakologie MeSH
- doxorubicin aplikace a dávkování farmakologie MeSH
- elektronová mikroskopie metody využití MeSH
- Gluconacetobacter růst a vývoj účinky léků MeSH
- individualizovaná medicína metody trendy využití MeSH
- karagenan * biosyntéza metabolismus MeSH
- konfokální mikroskopie metody využití MeSH
- lékové transportní systémy metody využití MeSH
- lidé MeSH
- nanokompozity chemie mikrobiologie využití MeSH
- protinádorové látky aplikace a dávkování terapeutické užití toxicita MeSH
- spektrofotometrie infračervená metody využití MeSH
- statistika jako téma metody MeSH
- techniky in vitro MeSH
- uhličitan vápenatý * chemická syntéza metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
PURPOSE OF THE STUDY: Each method of sterilisation has some effect on the structure and properties of UHMWPE and thus also on joint replacement longevity. This study was designed to compare, using objective methods of measurement, several kinds of sterilisation and to recommend the one which has the best prospect for making joint replacements last longer. MATERIAL AND METHODS: Two groups of UHMWPE samples were tested. Group 1 included virgin GUR 1020 polyethylene, non-modified and non-sterilised (Meditech, Germany). Group 2 comprised of three sets of samples sterilised with formaldehyde, gamma irradiation and ethylene oxide, respectively. In both groups, physicochemical properties were assessed by infrared spectroscopy (IR), and the oxidation (OI) and trans-vinyl (VI) indices, which show the degree of oxidation of a material, were determined. Free-radical concentrations were measured by the method of electron spin resonance (ESR). The mechanical properties of each sample were studied using small punch tests (SPT) and testing microhardness (MH). Any change in mechanical properties can affect, to various degrees, the quality and longevity of a prosthetic joint. RESULTS: The samples sterilised by gamma irradiation showed higher values of both the OI (0.37) and the VI index (0.038) than the other samples (OI, 0.02 to 0.05 and VI, 0). Also, the free-radical concentration was detectable only in the gamma-sterilised sample. Values obtained for mechanical properties were as follows: peak load in the range of 58.48 N (gamma irradiation) to 59.60 N (ethylene oxide); ultimate load in the range of 46.69 N (gamma irradiation) to 57.50 N (ethylene oxide); ultimate displacement in the range of 4.29 mm (gamma irradiation) to 4.58 mm (virgin polyethylene and formaldehyde); and work to failure in the range of 185.18 mJ (gamma irradiation) to 205.89 mJ (virgin polyethylene). Microhardness values were obtained in the following ranges: 41.2 to 44.6 MPa (virgin polyethylene); 40.2 to 44.1 MPa (formaldehyde); 46.1 to 49.3 MPa (gamma irradiation); and 40.3 to 44.2 MPa (ethylene oxide). DISCUSSION: The samples sterilised with formaldehyde and ethylene oxide have mechanical properties very similar to virgin polyethylene, they are not damaged by oxidation and do not contain free radicals. Owing to these characteristics, the immediate and long-term oxidation stability of the three samples is higher. The sample sterilised by gamma irradiation showed the presence of free radicals and immediate and long-term oxidative degradation. This results in the deterioration of mechanical properties and the growth of crystallinity due to enhanced oxidation and leads to higher polyethylene microhardness. CONCLUSIONS: Sterilisation with gamma irradiation results in oxidative degradation and mechanical property deterioration, which is one of the potential risks of a shorter life span of joint replacements. The use of ethylene oxide or formaldehyde does not change polymer properties nor has any effect on oxidation of materials. Therefore, a longer life expectancy of the joint replacements sterilised with ethylene oxide can be expected. The life span of their joint replacements is a key issue for the patients. Prosthetic joint loosening is painful and the patient often requires re-implantation. A higher number of re-implantations is associated with higher costs for the institution involved and, consequently, for the whole health care system. Although this study basically deals with chemical issues, it informs the surgeon of the latest developments leading to the improvement of implanted materials, which can increase the life expectancy of joint replacements and patients' satisfaction.
- MeSH
- artroplastiky kloubů metody MeSH
- ethylenoxid farmakologie MeSH
- formaldehyd farmakologie MeSH
- lidé MeSH
- polyethylen terapeutické užití MeSH
- protézy kloubů * škodlivé účinky klasifikace MeSH
- selhání protézy MeSH
- spektrofotometrie infračervená metody MeSH
- srovnávací výzkum účinnosti MeSH
- sterilizace metody MeSH
- testování materiálů metody MeSH
- záření gama * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- srovnávací studie MeSH
Thirteen mono-N-acyl derivatives of 2,6-diaminopimelic acid (DAP)-new potential inhibitors of the dapE-encoded N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE; EC 3.5.1.18)-were analyzed and characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies and two capillary electromigration methods: capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC). Structural features of DAP derivatives were characterized by IR and NMR spectroscopies, whereas CZE and MEKC were applied to evaluate their purity and to investigate their electromigration properties. Effective electrophoretic mobilities of these compounds were determined by CZE in acidic and alkaline background electrolytes (BGEs) and by MEKC in acidic and alkaline BGEs containing a pseudostationary phase of anionic detergent sodium dodecyl sulfate (SDS) or cationic detergent cetyltrimethylammonium bromide (CTAB). The best separation of DAP derivatives, including diastereomers of some of them, was achieved by MEKC in an acidic BGE (500 mM acetic acid [pH 2.54] and 60mM SDS). All DAP derivatives were examined for their ability to inhibit catalytic activity of DapE from Haemophilus influenzae (HiDapE) and ArgE from Escherichia coli (EcArgE). None of these DAP derivatives worked as an effective inhibitor of HiDapE, but one derivative-N-fumaryl, Me-ester-DAP-was found to be a moderate inhibitor of EcArgE, thereby providing a promising lead structure for further studies on ArgE inhibitors.
- MeSH
- amidohydrolasy antagonisté a inhibitory MeSH
- elektroforéza kapilární metody MeSH
- Escherichia coli enzymologie MeSH
- Haemophilus influenzae enzymologie MeSH
- inhibitory enzymů chemie farmakologie MeSH
- kyselina diaminopimelová chemie MeSH
- magnetická rezonanční spektroskopie metody MeSH
- spektrofotometrie infračervená metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
- MeSH
- biochemie * metody trendy MeSH
- chemické techniky analytické metody přístrojové vybavení trendy využití MeSH
- fluorescenční mikroskopie metody přístrojové vybavení MeSH
- publikování MeSH
- soudní lékařství * metody trendy MeSH
- spektrofotometrie infračervená metody přístrojové vybavení MeSH
- studium vysokoškolské MeSH
- výchova a vzdělávání * ekonomika organizace a řízení trendy MeSH
- Publikační typ
- práce podpořená grantem MeSH
- Klíčová slova
- 13-C-methacetin, infračervená spektroskopie, transmitance, absorbance, kumulovaná dávka,
- MeSH
- acetamidy * diagnostické užití chemie MeSH
- analýza rozptylu MeSH
- dechové testy * metody přístrojové vybavení MeSH
- dospělí MeSH
- jaterní cirhóza * MeSH
- jaterní testy * MeSH
- játra patofyziologie MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- ROC křivka MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- senzitivita a specificita MeSH
- spektrofotometrie infračervená metody přístrojové vybavení MeSH
- srdeční selhání MeSH
- studie případů a kontrol MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- srovnávací studie MeSH
Visible near-infrared (Vis-NIR) reflection spectroscopy and mid-infrared (mid-IR) reflection spectroscopy are cost- and time-effective and environmentally friendly techniques that could be alternatives to conventional soil analysis methods. Successful determination of spectrally active soil components, including soil organic matter (SOM), depends on the selection of suitable pretreatment and multivariate calibration techniques. The objective of the present review is to critically examine the suitability of Vis-NIR (350-2500 nm) and mid-IR (4000-400 cm(-1)) spectroscopy as a tool for SOM quantity and quality determination. Particular attention is paid to different pretreatment and calibration procedures and methods, and their ability to predict SOM content from Vis-NIR and mid-IR data is discussed. We then review the most recent research using spectroscopy in different calibration scales (local, regional, or global). Finally, accuracy and robustness, as well as uncertainty in Vis-NIR and mid-IR spectroscopy, are considered. We conclude that spectroscopy, especially the mid-IR technique in association with Savitzky-Golay smoothing and derivatization and the least squares support vector machine (LS-SVM) algorithm, can be useful in determining SOM quantity and quality. Future research conducted for the standardization of protocols and soil conditions will allow more accurate and reliable results on a global and international scale.
A new impurity was detected and determined using gradient ion-pair UHPLC method with UV detection in zolmitriptan (ZOL). Using MS, NMR and IR study the impurity was identified as (4S,4'S)-4,4'-(2,2'-(4-(dimethylamino)butane-1,1-diyl)bis(3-(2-(dimethylamino) ethyl)-1H-indole-5,2-diyl))bis(methylene)di(oxazolidin-2-one) (ZOL-dimer). The standard of ZOL-dimer was consequently prepared via organic synthesis followed by semipreparative HPLC purification. The UHPLC method was optimized in order to selectively detect and quantify other known and unknown process-related impurities and degradation products of ZOL as well. The presented method which was validated with respect to linearity, accuracy, precision and selectivity has an advantage of a very quick UHPLC chromatographic separation (less than 7 min including re-equilibration time) and therefore is highly suitable for routine analysis of related substances and stability studies of ZOL.
- MeSH
- hmotnostní spektrometrie metody MeSH
- kontaminace léku MeSH
- limita detekce MeSH
- magnetická rezonanční spektroskopie metody MeSH
- oxazolidinony chemie izolace a purifikace MeSH
- oxazoly izolace a purifikace MeSH
- spektrofotometrie infračervená metody MeSH
- spektrofotometrie ultrafialová metody MeSH
- techniky syntetické chemie metody MeSH
- tryptaminy chemie izolace a purifikace MeSH
- vysokoúčinná kapalinová chromatografie metody MeSH
- Publikační typ
- časopisecké články MeSH
Near-infrared (NIR) spectroscopy offers many advantages for a wide range of industrial applications. In combination with multivariate data analysis NIR spectroscopy offers interesting utilization for both qualitative and quantitative analysis. The method is fast and nondestructive and can be implemented in process analysis. The review presents recent pharmaceutical applications of NIR spectroscopy, e.g. in raw materials testing, direct analysis of dosage forms, and process monitoring and process control.
