Radiation sterilization of anthracycline antibiotics in solid state.

The impact of ionizing radiation generated by a beam of electrons of 25-400 kGy on the stability of such analogs of anthracycline antibiotics as daunorubicin (DAU), doxorubicin (DOX), and epidoxorubicin (EPI) was studied. Based on EPR results, it was established that unstable free radicals decay exponentially with the half-time of 4 days in DAU and DOX and 7 days in EPI after irradiation. Radiation-induced structural changes were analyzed with the use of spectrophotometric methods (UV-Vis and IR) and electron microscope imaging (SEM). A chromatographic method (HPLC-DAD) was applied to assess changes in the contents of the analogs in the presence of their impurities. The study showed that the structures of the analogs did not demonstrate any significant alterations at the end of the period necessary for the elimination of unstable free radicals. The separation of main substances and related substances (impurities and potential degradation products) allowed determining that no statistically significant changes in the content of particular active substances occurred and that their conversion due to the presence of free radicals resulting from exposure to an irradiation of 25 kGy (prescribed to ensure sterility) was not observed.

Multiferroic BiFeO3 nanoparticles studied by electron spin resonance, X-ray diffraction and transmission electron microscopy methods.

The properties of multiferroic BiFeO3 nanoparticles with core-shell structure produced by mechanically activated room temperature synthesis were studies by electron spin resonance spectroscopy and X-ray diffraction. The data reveal essential differences in ordered and disordered regions among as-prepared and annealed samples. The thermally-induced increase in the average size of the grains and disappearance of the disordered grain shell determined from the electron spin resonance and X-ray diffraction are in a good agreement and were confirmed by transmission electron microscopy observations. Ferro- and ferrimagnetic ordering was observed in as-prepared BiFeO3 nanograins, whereas antiferromagnetic order was apparent in the annealed material. The results show that the electron spin resonance spectroscopy can be considered as an useful method to determine the type of magnetic ordering in multiferroic nanoparticles.

Proton dynamics in Rb(3)H(SO(4))(2) doped with Mn(2+) studied by EPR and impedance spectroscopy.

The temperature dependence of the linewidth ΔB(pp) and spin Hamiltonian parameters of Rb(3)H(SO(4))(2) (RHS) crystals were studied by X-band continuous-wave electron paramagnetic resonance. Direction cosines of the zero-field-splitting (ZFS) tensor and the coordination of the Mn(2+) impurities in the crystal lattice were determined in the temperature range 20-450 K. The EPR spectra of crystalline samples and their irreversible changes into pseudo-powder spectra after heating above the superprotonic phase transition temperature were found. Our studies of electric conductivity have shown that, for crystals doped with Mn(2+) ions, the conductivity values increase after heating by about one order of magnitude at intermediate temperatures (below the transition temperature to the superionic phase) in comparison with those of the pure RHS.

New aspects of the low-concentrated aniline polymerization in the solution and in SiC nanocrystals dispersion.

Results of the simultaneous in-situ UV-vis and open-circuit potential (OCP) monitoring of the low-concentrated aniline (An) polymerization in the presence of camphorsulfonic acid (CSA) suggested that during the induction period (IP) step a transition state formed, which probably included anilinium cation and the oxidant anion, antecedent to a propagation step. No aniline oligomers were registered at this stage but they appeared at the beginning of the propagation step under the investigation conditions. The moments of formation of insoluble pernigraniline phase and appearance of emeraldine units in the growing pernigraniline chains were ascertained by the comparison of kinetic and OCP profiles of the polymerization process both in the solution and in SiC dispersion water mediums. It is deduced that pernigraniline reduction by aniline molecules begins earlier than it is generally accepted (i.e., earlier than OCP maximum is reached) and probably in parallel to a continuing appearance of pernigraniline units even in the same chains that undergo the reduction. It was found that an addition of the SiC dispersion phase into the polymerization mixture accelerates differently all stages of the aniline polymerization. Finally, this polymerization process leads to the formation of polyaniline (PANI)-CSA shell with thickness in the range from 0.5 nm to a few nm at the SiC nanocrystals surface.

Increased proapoptotic activity of electron beam irradiated doxorubicin and epirubicin in multidrug-resistant human leukemic cells.

This study evaluated the effect of electron beam irradiation on the cytotoxic activity of anthracycline antibiotics such as doxorubicin (DOX), epirubicin (EPI), and dunorubicin (DAU) in human acute lymphoblastic leukemia cell line CCRF-CEM and its multidrug-resistant variant CCRF-VCR1000 cell line characterized by the overexpression of ABCB1 gene. Drugs were irradiated at doses of 10 and 25 kGy. Data from EPR studies proved that the highest concentration of free radicals was found in DOX and that the number of stable free radicals is always greater after irradiation. In in vitro studies, a higher cytotoxic activity of irradiated DOX and EPI in multidrug-resistant CCRF-VCR1000 cells was observed. This tendency was maintained during the storage at 4 °C for 90 days. Changes in CCRF-CEM cells' viability were not dependent on the irradiation status and its dose and were only drug-concentration dependent in all measurement time points. It was proved that increased potency of 25 kGy e-beam irradiated drugs results from their enhanced proapoptotic activity. Apoptotic cell death observed in CCRF-VCR1000 cells treated with irradiated drugs was caspase-8, -9, and -3 dependent and related to the increased Bax/Bcl-2 ratio. No significant differences in the effects of irradiated and non-irradiated drugs on p53 and NFκB transcription factor level and their translocation to the nucleus were noted. Increased activity of the irradiated drugs was not dependent on ABCB1 level.

The characteristics of fermentation abilities of K. fragilis immobilized on Siran.

The aim of this paper was to evaluate the suitability of Siran, a highly porous mineral carrier, to immobilization of Kluyveromyces fragilis--directly lactose-fermenting yeast. The ethanol concentration in the post-fermentation mash was 4.7-5.8% v/v and was less advantageous than in previous experiments with calcium alginate (on average 6.04% v/v in 9 sequential fermentations). The introduction of another yeast strain to the experiment--S. cerevisiae--enhanced the efficiency of the lactose mash fermentation. The ethanol concentration in the mash in sequential series of the process increased on average to 6.14% v/v.

The selectivity of some fungal lipases.

Selectivity is one of the most important lipase properties which depends on a wide range of factors. In order to choose the right enzyme for a special purpose, it is necessary to check its selectivity. Fatty acid selectivity of lipases determined for natural substrales was different from that determined for p-nitrophenyl esters and those determined for each substrate. Enantoiselectivity of lipase from Mucor circinelloides (MCL) determined for 2 was over 100 (E > > 100). In this case, inversion of enantiopreferences was observed; the conversion was 10% and (R)-alcohol was preferentially produced

Improvement of beta-galactosidase immobilization and its application to ethanol fermentation of lactose.

To intensify ethanol fermentation of lactose, a co-immobilized biocatalyzer was used. It consisted of yeast cells of Saccharomyces cerevisiae co-immobilized with beta-galactosidase preparation from A. oryzae. The experiment was focused on the improvement of biocatalyzer operational stability. An increase in the concentration of a carrier (2% calcium alginate) did not improve the effectiveness of binding beta-galactosidase. However, its initial cross-linking with glutaraldehyde and its co-immobilization with distillery industrial yeast produced a stable biocatalyzer able to ferment mash from permeate (12% lactose) with an average efficiency of 6.5% v/v of alcohol during 10 experimental series (30 days).

The effect of some conditions on the secretion of extracellular beta-galactosidase synthesised by Kluyveromyces fragilis 28.

To induce extracellular secretion of beta-galactosidase synthesised by Kluyveromyces fragilis 28, it was used glycine, L-asparagine, L-leucine, dimethyl fluoride, dimethyl sulfoxide, cetyldimethylethylammonium bromide, penicillin G and glycolipids from Candida antarctica. The highest increase in the secretion of beta-galactosidase was obtained in the yeast culture cultivated in the medium with polypeptone when glycine was used as the secretion inductor. The extracellular activity of beta-galactosidase reached 0.416 A.U./ml, and was 10-fold higher than the beta-galactosidase activity reported in the control group.

The application of immobilized biocatalyzers to intensify the ethanol fermentation of lactose.

Ethanol fermentation of lactose mash by biocatalyzers immobilized in sodium alginate was studied in order to improve the process productivity and economy. The fermentation effectiveness of S.cerevisiae co-immobilized with a p-galactosidase and the directly lactose- fermenting immobilized yeast: K. fragilis and C. pseudotropicalis were compared The application of the immobilized K. fragilis produced desirable results and even after its 9th (18 days) fermentation, the immobilized yeast provided the stable high fermentation level (on average about 6 ralvol of ethano/) while maintaining its activity. Such lactose-mash fermentation was greater than in conventional method (by free cells). In addition, the application of s. cerevisiae co-immobilized with p-galactosidase produced somewhat greater ferm levels than the conventional method, however, the system stability deteriorated after 6 days of fermentation.

A comparative study on galactoologosaccharide synthesis by selected beta-galactosidase preparations.

The transgalactosilating ability of beta-galactosidase preparations obtained from Kluyveromyces fragilis, Penicillium canescens, and Escherichia coli was investigated. In samples of hydrolysates of 20% lactose solutions without or with a 2% addition of glucose, the galactose or fructose obtained with the use of the investigated preparations and the content of saccharides was determined with the HPLC method. Under experimental conditions, the highest quantity (56.0-64.1%) of galactooligosaccharides was synthesised by beta-galactosidase obtained from E. coli, while the lowest number (11.25-25.2%) was obtained by beta-galactosidase obtained from P. canescens. Beta-galactosidase from E. coli also synthesised considerable amounts of lactulose.

Low temperature short-range ordering caused by Mn²(+) doping of Rb3H(SO4)2.

The low temperature behaviour of Rb3H(SO4)2 and Rb3D(SO4)2 and their doped analogues was investigated by means of their dielectric response. Electron paramagnetic resonance was used to control the impurity concentration. Influence of different admixtures on ferroic properties is discussed. It has been shown that an appropriately chosen impurity in doped Rb3H(SO4)2 can lead to a short-range ordering similar to that observed for doped incipient ferroelectric-like SrTiO3 and KTaO3.