Noninvasive estimation of the oxygen status of experimental tumors by diffuse optical spectroscopy

The potentialities of diffuse optical spectroscopy for noninvasive estimation of the oxygen status of experimental tumors have been demonstrated. The distribution of total, oxygenated, and deoxygenated hemoglobin, as well as the level of oxygen saturation of blood have been assessed using two tumor models differing in the histological structure and functional characteristics. The results obtained by the optical method have been verified by immunohistochemical examination of tissue specimens with an exogenous hypoxia marker pimonidazole.     

Verification of a decrease in the rigidity of the phage λ DNA polymeric chain in low ionic strength aqueous solutions by testing the polymer-polymer interlink interactions

Changes in the rigidity of the polymeric chain of phage λ double-strand DNA have been studied by laser correlation spectroscopy. It was shown that, as the ionic strength increases, the effect of the screening of the hydrodynamic interaction of the links of the polymeric chain specific for polymeric coils arises in a DNA solution. It is assumed that the screening occurs when the threshold of the overlapping of DNA coils is achieved. The overlapping of coils is the result of a previously observed significant rise of DNA coil size from abnormally small DNA coils in low ionic strength buffers (about 10⁻² M Na⁺ or less) to maximum possible large coils in the 5SSC and 5SSC-like buffers. Further analysis of the far interlink interactions in linear lambda phage DNA coils in similar buffers at pH 7 and 4 confirms the earlier proposal about the role of H+ ions in the appearance of abnormally small DNA coils. The abnormal decrease in the DNA coil size in low ionic strength buffers is not a specific feature of λ phage DNA only.     

Biological activity of water-soluble nanostructures of dihydroquercetin with cyclodextrins

The biological properties of dihydroquercetin (DHQ) modified by including it into the ring of β-cyclodextrin (β-CD) to give it more water-soluble properties have been investigated. It was shown that the peroral administration of the DHQ/β-CD complex provides a long increase of DHQ concentration in rat blood (up to 7.5 h), and, unlike pure DHQ, the complex does not accumulate in the liver. As DHQ is released from the complex, it penetrates into liposome membranes, changing their thermodynamic characteristics. DHQ decreases the specific heat absorption, enthalpies, and temperature maximum of lipid melting and increases the transition half-width. This property is used to estimate the stability of the DHQ/β-CD complex. It was shown that complex DHQ/β-CD is not stable, and DHQ molecules slowly leave the complex in water environment. Seven and a half hours after the peroral injection of drugs, DHQ was found in the blood plasma of rats to which water-soluble complex DHQ/βCD was injected and in the liver of rats to which free DHQ was injected. Thus, DHQ/βCD not only is a more water-soluble complex but also it slowly releases DHQ, supporting long a low concentration of the free form of DHQ and providing the penetration of DHQ into the blood stream. After several weeks of feeding old mice with antioxidants, the activity of mitochondrial enzymes was restored to the level observed in young animals.     

Nanocrystalline ceria based materials—Perspectives for biomedical application

Nanocrystalline ceria possesses a unique complex of physical and chemical properties making it highly bioactive material. In this review, modern data on the action of nanocrystalline ceria on cells, micro- and macroorganisms are analyzed. Special attention is paid to the analysis of the factors affecting protective properties of CeO₂ with respect to the living systems.     

The structural and dynamic model of the serotonin 5-HT3 receptor. Comparative analysis of the structure of the channel domain of pentameric ligand-gated ion channels

The three-dimensional structure of the 5-HT3 receptor is currently unknown. An available structure of the nicotinic acetylcholine receptor closely related by homology to the 5-HT3 receptor was used as a template for the computer-based homology modeling of the 5-HT3 receptor. The study of the ion migration through the channel by the steered molecular dynamics method has shown that the steric factor in the region of residue Thr279 and the region of Glu272, Asp293 influences the ion transmission. The characteristic of the close interaction between the ion and the amino acid substitutions of the 5-HT3 channel was studied by computing the energy profile using constraint force molecular dynamic simulations. The amino acid sequence responsible for selective ion transmission has been investigated. The structure of the channel domain of the serotonin 5-HT3 receptor as a universal functional unit of the ligand-gated ion channels was discussed.     

Estimation of luminescent properties of the derivatives of polymethine probes on their interaction with cells of different types

The spectral and luminescent properties of the derivatives of polymethine probes based on 3,3′-dialkyloxacarbocyanine bromide (H-510) and 1,1′-dialkyl-3,3,3′,3′-tetramethylindodicarbocyanine bromide (D-307) (where alkyl is ethyl or octadecyl groups) on accumulation in bone marrow and liver cells of rats have been compared. The general regularities in the interaction between the probes and the membrane microenvironment have been revealed for each type of the cells. It was found that the structural features of membranes and the length of the chains of alkyl substitutes essentially affect the redistribution of dye molecules in the binding centers of particular types, as evidenced by changes in the spectral characteristics of probes. It has been shown by microfluorimetry that the accumulation of short-chain derivatives in single cells is representative of the distinctions in the parameters of their functional metabolic state, which coincides with the present view of the heterogeneous structure of these cellular populations. The hormonal action and the influence of incubation without serum on the intensity of cellular processes were accompanied by changes in the fluorescence of cells stained with the ethyl derivatives of the probes H-510 and D-307. This fact allows us to consider them as optical indicators of the cellular activity. The dye D-307 was found to be more resistant to photodestruction than H-510 both in single cells and model system.     

Bumblebees (Hymenoptera,Apidae) in the forest-tundra and tundra of Northeast Europe

Ways of formation of the topical bumblebee complexes are considered on the basis of long-term research carried out in 2002–2009, in different regions of the Nenets Autonomous Area. The specific features of species distribution are analyzed, and the role of anthropogenic changes in the plant communities for the bumblebees is revealed. The complex of the dominant species in the forest-tundra and tundra zones of Northeast Europe is determined.     

Estimation of the biological age in females of the taiga tick (Ixodes persulcatus: Ixodidae) by changing of fat resources in the organism

The method of estimation of the biological age in hungry tick females by revealing of the degree of lipid inclusions in the cells of the midgut and of the fat body is assumed. In order to estimate the degree of fat reserves in hungry females, live ticks were dissected and fragments of their internal organs were vitally stained with the saturated solution of Sudan III in 70% ethanol. Three age-specific groups were established, including (I) young females whose intestines and fat body were filled with fat inclusions; (II) mature females whose fat reserves were partially expended; and (III) old females possessing solitary fat inclusions in their midgut and fat body.     

Vanadyl bisacetylacetonate protects β cells from palmitate-induced cell death through the unfolded protein response pathway

Endoplasmic reticulum (ER) stress induced by free fatty acids (FFA) is important to β-cell loss during the development of type 2 diabetes. To test whether vanadium compounds could influence ER stress and the responses in their mechanism of antidiabetic effects, we investigated the effects and the mechanism of vanadyl bisacetylacetonate [VO(acac)₂] on β cells upon treatment with palmitate, a typical saturated FFA. The experimental results showed that VO(acac)₂ could enhance FFA-induced signaling pathways of unfolded protein responses by upregulating the prosurvival chaperone immunoglobulin heavy-chain binding protein/78-kDa glucose-regulated protein and downregulating the expression of apoptotic C/EBP homologous protein, and consequently the reduction of insulin synthesis. VO(acac)₂ also ameliorated FFA-disturbed Ca²⁺ homeostasis in β cells. Overall, VO(acac)₂ enhanced stress adaption, thus protecting β cells from palmitate-induced apoptosis. This study provides some new insights into the mechanisms of antidiabetic vanadium compounds.