Search

Applications of nonequilibrium low-temperature oxygen electron-beam plasma (EBP) for the controllable processing of biopolymers (crab shell chitosan and softwood lignocellulose) are described. Water-soluble chitooligosaccharides with weight-average molecular mass $M_{w} = 800$ –2000 Da and polymerization degree varying from dimers to heptamers were obtained after the EBP-stimulated chitosan destruction; trimers being the most predominant. Water solutions of the EBP-produced chitosan oligomers enhanced the seeds germination and stimulated green mass formation in barley Hordeum vulgare. The EBP processing of lignocellulose resulted in its amorphization and formation of additional oxygen containing functional groups at the surface of the biomaterial. [ABSTRACT FROM AUTHOR]

The transcription factor (TF) HIF1 is one of the most important factors of adaptation to chronic cerebral hypoxia. However, under the conditions of acute hypoxia and reoxygenation, the stress response TF (NRF2) becomes important. The interaction between these proteins at the level of regulation of antioxidant defense and glucose metabolism has been shown previously in hypoxia-sensitive cancer tumors. Here, we have studied the effect of severe hypobaric hypoxia (SH) on HIF1- and NRF2-dependent processes in the rat neocortex. We revealed the joint regulation of glutathione-dependent antioxidant systems by these proteins, which influenced the total antiradical activity and the cellular redox status. In particular, HIF1 inhibition prevented the SH-induced oxidative shift 23 h after reoxygenation, which was accompanied by an increase in the content of total glutathione and the activity of glutathione reductase. Both of these effects were NRF2-dependent, which suggests that this transcription factor is activated in response to SH in combination with HIF1 inhibition. The data confirm the previous hypothesis about the maladaptive effect of HIF1 under the conditions of acute hypoxia and reoxygenation and point to the contribution of NRF2 the protective mechanisms in the post-hypoxic period. The hypothesis of interaction between these transcription factors in the (post)hypoxic period requires further verification and may have substantial influence on understanding the molecular pathomechanisms of cerebral hypoxia. [ABSTRACT FROM AUTHOR]

In the present study, we estimated the levels of various forms of glutathione and the state of the glutathione antioxidant system in the subcellular fractions of the rat brain and in the liver during early postnatal ontogeny. Several groups of animals were studied, including 10-, 20-, and 30-day-old male Wistar rats, which allowed us to study different periods of brain maturation. It was shown that during the postnatal development of the rat brain from day 10 to day 30 the contents of both reduced and oxidized forms of glutathione decreased. In early ontogeny, when the activity of most of antioxidant enzymes is low, reduced glutathione may perform an antioxidant function. On the other hand, despite the decrease in the absolute value, the portion of GSH in the total glutathione pool increased and modified the redox state of the cells toward a more reduced condition. The decrease in the GSH level may be related to lower activity of glutathione reductase, which reduces oxidized glutathione, or to increased activity of the antioxidant enzymes, such as glutathione peroxidase and glutathione-S-transferase, which use GSH as a cofactor in their reactions. [ABSTRACT FROM AUTHOR]

In this work, new efficient drug delivery systems based on cellulose nanofiber–titania nanocomposites grafted with three different types of model drugs such as diclofenac sodium, penicillamine-D and phosphomycin were successfully synthesized and displayed distinctly different controlled long-term release profiles. Three different methods of medicine introduction were used to show that various interactions between TiO2 and drug molecules could be used to control the kinetics of long-term drug release. All synthesis reactions were carried out in aqueous media. The morphology, chemical structure and properties of the obtained materials were characterized by SEM, TEM and AFM microscopy, nanoparticle tracking analysis, X-ray diffraction, and TGA analysis. According to FT-IR and UV-Vis spectroscopy data, the titania binds to cellulose nanofibers via formation of ester bonds and to drug molecules via formation of surface complexes. The drug release kinetics was studied in vitro for diclofenac sodium and penicillamine-D spectrophotometrically and for phosphomycin using a radio-labeling analysis with 33P-marked ATP as a model phosphate-anchored biomolecule. The results demonstrated that the obtained nanocomposites could potentially be applied in transdermal drug delivery for anesthetics, analgesics and antibiotics. [ABSTRACT FROM AUTHOR]

TiO2 materials were prepared froma titanium isopropoxide precursor by sol-gel processing in watermedia with or without various templates (polyethylenimine or Pluronic P-123). The photocatalytic efficiency of the samples was found to depend strongly on the use of and type of template added. Titania/Pluronic sols resulted in homogeneous anatase TiO2-rutile with uniform particle size distribution after calcination (400°C). Optical properties of the samples were characterized by UV-Vis spectroscopy and crystalline structures by X-ray diffraction. A surfactant-assisted sol-gel process retarded crystallization of the anatase and rutile titania, which resulted in smaller grain sizes and presumably a larger active surface area. The morphology of the surfaces was obtained by AFM techniques. The highest photobleaching rate was found for samples deposited from the sol with the addition of the Pluronic P-123 surfactant, and it was almost twice as high as that for films deposited from sols with polyethylenimine. 1. Introduction Titania coatings with high specific surface area and with narrow pore size distribution have a big prospect of practical application in such areas as solar energy transformation [1] and photocatalysis [2-7] for water and air clearing and processing, as self-cleaning coatings for windows and tiles [8]. The pore size and specific surface area substantially affect the physical properties of these materials and can play a significant role in their activity. For example, catalytic application demands an adjustable porosity for optimization of rate of reagent diffusion towards adsorption centers and a large surface area for the maximum interaction between the reagent flow and the catalyst surface. Titania-based coatings can be synthesized by various methods, but sol-gel process is the most applied as this method possesses some advantages, such as homogeneity at molecular level, a wide range of a precursor selection, control over microstructure, low demands upon reagent purity, possibility of a fine adjustment of the end product properties, simplicity of process, and low temperature and cost. Synthesis of titania by sol-gel method is usually attained by hydrolysis of titanium alkoxide precursors. Nevertheless, two various approaches can be applied accordingly to process parameters. So far, the most [ABSTRACT FROM AUTHOR]

Describes the involvement of brain dopaminergic structures in neuroimmunomodulation. Decrease of the intensity of immune response in rats immunized with sheep red blood cells; Increase of the activity of central DAergic system; Mechanisms of neuroimmunomodulation.