Multifrequency electron paramagnetic resonance (EPR) spectroscopy was applied to study Fe(III)−MCM-41 mesoporous molecular sieves with incorporated carotenoids. It was demonstrated that ...high-frequency/high-field EPR is a promising technique to increase spectral resolution for proper assignment of different Fe3+ sites, which cannot be resolved by the X-band experiments. The broad unresolved at 9 GHz EPR line in the g = 2 region is due to overlapping signals from Fe3+ sites with different zero field parameters. The peak with g = 2.45 is tentatively assigned to aggregated Fe3+. The signal with g = 2.07 can be attributed to Fe3+ coordinated to oxygen atoms on the surface of the pore. A narrow line with g x = g y = 2.003, g z = 1.99, and E/D = 0.3 was attributed to a single Fe3+ site. The X-band and 94 GHz EPR measurements indicated that extraframework iron species at the surface of the mesopores are mostly responsible for carotenoid oxidation in molecular sieves. ENDOR measurements revealed the orientation of 7‘-apo-7‘,7‘-dicyano-β-carotene and canthaxanthin within Fe−MCM-41.
Astroviral infection in Russian Federation Podkolzin, A T; Konovalova, T A; Iakovenko, M L ...
Voprosy virusologiĭ,
2013 May-Jun, Letnik:
58, Številka:
3
Journal Article
Recenzirano
The astroviral infections are considered among the most common pathogens of gastroenteritis in children. The incidence, molecular epidemiology and clinical manifestations of the astrovirus infection ...in children hospitalized with acute gastroenteritis, in various areas of the Russian Federation from 2004 to 2010 was determined.
Canthaxanthin and 8‘-apo-β-caroten-8‘-al radical cations chemically prepared on activated silica−alumina and in CH2Cl2 solution containing AlCl3 were studied by pulsed EPR and ENDOR spectroscopies. ...Both the 1D three-pulse ESEEM and the 2D HYSCORE spectra of the carotenoid−AlCl3 mixtures exhibited the 27Al nuclei peak at 3.75 MHz. This indicates electron-transfer interactions between carotenoids and AlIII ions resulting in the formation and stabilization of carotenoid radical cations. Davies ENDOR measurements of the canthaxanthin radical cation on silica−alumina determined the hyperfine couplings of β protons belonging to three different methyl groups with a H1 = 2.6 MHz, a H2 = 8.6 MHz, and a H3 ca. 13 MHz. The principal components of the proton hyperfine tensors were obtained from HYSCORE spectra in AlCl3 solutions and on the solid support. Identification of the protons was made on the basis of isotropic hyperfine couplings determined by RHF−INDO/SP molecular orbital calculations. In frozen AlCl3 solution, the C(7,7‘)-Hα and C(14,14‘)-Hα α protons were observed for canthaxanthin and the C(8 or 14‘)-Hα and C(15‘)-Hα were observed for 8‘-apo-β-caroten-8‘-al. On the silica−alumina support, the C(10,10‘)-Hα, C(11,11‘)-Hα, and C(15,15‘)-Hα α protons were measured for canthaxanthin and the C(12)-Hα and C(15‘)-Hα were measured for 8‘-apo-β-caroten-8‘-al. Some protons with large isotropic couplings (>10 MHz) determined from HYSCORE analysis could be assigned to β protons, but the principal components of their hyperfine tensors are much more anisotropic than those reported previously for β protons. We suggest that cis/trans isomerization of carotenoids on silica−alumina results in stabilization of di-cis isomers with large isotropic couplings for some α protons which are comparable to those of β protons. HYSCORE is a promising technique to increase spectral resolution for proper assignment of protons with large hyperfine anisotropy, which cannot be resolved by ENDOR spectroscopy.
Exogenous NO donor 3,3-bis-(nitroxymethyl)oxetane (NMO) was synthesized at the Institute for Problems of Chemical Physics (Russian Academy of Sciences). This compound was shown to inhibit cell death ...(apoptosis and necrosis) in cyclophosphamidesensitive and cyclophosphamide-resistant P388 murine tumor. p53 protein was expressed in both lines of tumor cells. NO donor NMO had little effect on p53 protein expression in cells of both stains. Our results suggest that the proapoptotic effect of NMO is mediated by the p53-independent molecular mechanisms.
EPR measurements demonstrate efficient charge separation on carotenoid-modified titanium dioxide nanoparticles (7 nm). Strong complexation of carotenoids containing terminal carboxy groups (−CO2H) ...with the TiO2 surface leads to electron transfer from the adsorbed carotenoid molecule to the surface trapping site. For these systems, EPR signals of the carotenoid radical cations Car•+ and the electrons trapped on the TiO2 are observed before irradiation (77 K). Their UV−visible spectra show an absorption band with a maximum near 650 nm that is characteristic of the trapped electrons. Surface modification of the TiO2 by other carotenoids results in the formation of a complex with an optical absorption band near 545 nm. These systems form charge-separated pairs Car•+···TiO2(e- tr)surf. TiO2(e- tr)latt. only upon 365−600 nm illumination at 77 K. Complexation of the TiO2 colloids with carotenoids enhances spatial charge separation, shifts the absorption threshold into the visible region, and thus greatly improves the reducing ability of the semiconductor. Photoreduction of acceptor molecules such as 2,5-dichloro-1,4-benzoquinone, nitrobenzene, and oxygen is demonstrated.
Four fractions of IgG antibodies to native DNA (nDNA) were obtained from blood of patients with systemic lupus erythematosus (SLE). These antibodies displayed a thermostable DNA-hydrolyzing activity ...and were different in affinity for DNA-cellulose and sorption on DEAE-cellulose. DNA-hydrolyzing antibodies to nDNA are metal-dependent endonucleases, cause mainly single-strand breaks in DNA, and are active over a wide range of pH. By atomic-force microscopy, three-dimensional images of DNA complexes with DNA-hydrolyzing antibodies to nDNA were obtained with nanometer resolution, and a nonprocessive action mechanism was shown for the DNase activity of antibodies to nDNA.
We have analyzed the efficacy of nootropic drug pantogam in the treatment of hyperkinetic disorders in children aged 6-12 years. The results of the randomized placebo-controlled trial demonstrated ...the decrease of major symptoms of hyperkinetic disorders (inattention, hyperactivity, impulsivity), comorbid mental and behavior disorders, the improvement of cognitive functions in the group of children treated with pantogam during 6 weeks and the absence of significant changes in the placebo group. It has been concluded that pantogam is effective in the treatment of hyperkinetic disorders in children.
Exogenous NO donor 3,3-bis-(nitroxymethyl)oxetane (NMO) was synthesized at the Institute for Problems of Chemical Physics (Russian Academy of Sciences). This compound was shown to inhibit Ca²⁺-ATPase ...isolated from normal muscular cells and tumor cells. Both hydrolytic and transport functions of the enzyme were inhibited under these conditions. These changes were probably related to changes in membrane structure caused by NO donor. Our results suggest that changes in intracellular Ca²⁺ concentration can modulate the formation of tumor drug resistance.
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