Photoactivated DNA analogs of substrates of the nucleotide excision repair system and their interaction with proteins of NER-competent extract of HeLa cells. Synthesis and application of long model DNA

Long linear DNA analogs of nucleotide excision repair (NER) substrates have been synthesized. They are 137-mer duplexes containing in their internal positions nucleotides with bulky substitutes imitating lesions with fluorochloroazidopyridyl and fluorescein groups introduced using spacer fragments at the 4N and 5C positions of dCMP and dUMP (Fap-dC- and Flu-dU-DNA) and DNA containing a (+)-cis-stereoisomer of benzo[a]pyrene-N2-deoxyguanidine (BP-dG-DNA, 131 bp). The interaction of the modified DNA duplexes with the proteins of NER-competent HeLa extract was investigated. The substrate properties of the model DNA in the reaction of specific excision were shown to vary in the series Fap-dC-DNA << Flu-dU-DNA < BP-dG-DNA. During the experiments on affinity modification of the proteins of NER-competent extract, Fap-dC-DNA (137 bp) containing a ³²P-label in the photoactive nucleotide demonstrated properties of a highly efficient and selective probe. The set of the main targets of labeling included polypeptides of the extract with the same values of apparent molecular weights (35–90 kDa) as when using the shorter (48 bp) Fap-dC-DNA. Besides, some of the extract proteins were shown capable of specific and effective interaction with the long analog of NER substrate. Electrophoretic mobility of these proteins coincided with the mobilities of DNA-binding subunits of XPC-HR23B and PARP1 (∼127 and T]115 kDa, respectively). The 115-kDa target protein was identified as PARP1 using NAD⁺-based functional testing. The results suggest that the linear Fap-dC-DNA is an unrepairable substrate analog that can compete with effective NER substrates in the binding of the proteins responsible for lesion recognition and excision.     

Complex radiodiagnosis of oropharyngeal neoplasms

The paper describes the magnetic resonance imaging (MRI) and spiral computed tomographic (SCT) symptoms of malignant and benign tumors of the oral cavity and throat. It also depicts different types of tumors, such as squamous cell carcinoma, adenocarcinoma, papilloma, and lipoma. The MRI and SCT symptoms of malignant and benign tumors, as well as metastatic lesion in lymph nodes and destruction of bone elements are described in detail.     

Effect of gold nanoparticles on mouse spermatogenesis

The response of the mouse male germ cells exposed to gold nanoparticles (??2.5 nm) was studied. Our investigation demonstrates that treatment with Au nanoparticles for four days does not impair the architecture of the spermatogenic epithelium. Cytogenetic evaluation using micronucleus assay showed that gold nanoparticles can affect the chromosomes of early primary spermatocytes. However, gold nanoparticles did not induce chromosome abnormalities in spermatogonial stem cells. Further, the cauda epididymal sperm was isolated on the 14th day after treatment and was incubated in SDS solution (Na dodecyl sulphate) and then in a solution containing DTT (dithiothreitol) to induce nuclear chromatin decondensation. Observations showed that after four days of treatment of spermiogenic (postmeiotic) cells with gold nanoparticles the decondensation process had no differences from the control. On the contrary, in the experiment with the same cells and period of fixation but with a single exposure to gold nanoparticles, the number of mature gametes with totally decondensed nuclei reached 100% as opposed to 44% in the controls.     

Dynamic characteristics of the external respiratory function in young male residents of the north during the annual cycle

The following aspects were studied during the annual cycle in young men (aged 19.0 ± 0.9 years) living in northern European Russia (62°N): the peak and instantaneous volumetric flow rates (PVFR and IVFR, respectively) at the moments of expiration of 25, 50, and 75% of the forced vital capacity of the lungs (FVC); the average volumetric expiratory flow rate in the process of expiration from 25 to 75% of FVC; the respiratory rate; and the time of attainment of PVFR and FVC. The pulmonary function parameters were determined using an SPM-01-R-D microprocessor spirograph. It was found that only the velocity characteristics of the external respiratory function significantly (the F test) changed in young men during the annual cycle; the time functions were not significantly different. A greater variation in the velocity parameters of the external respiratory function was found during the annual cycle compared to those for the inhabitants of temperate latitudes, which is indicative of adaptive reactions of the external respiratory function and a slightly restricted bronchial patency at the level of mediumand, especially, small-caliber bronchi. The PVFR and IVFR at the moments of expiration of 25, 50, and 75% of FVC and the average volumetric expiratory flow rate in the 25–75% range of the FVC in the male residents of the North are higher during the cold season and lower in the warm season.     

Structural polymorphism of the liquid-crystalline dispersions formed from the double-stranded DNA molecules complexed with synthetic polycations

The double-stranded, linear DNA molecules form the liquid-crystalline dispersions (LCD) in water-salt solutions containing positively charged polyconidin molecules. It was established from the analysis of the absorption spectra of the LCDs formed from (DNA-polyconidin) complexes, that the mean size of the particles of these dispersions is equal to -6000 angstroms. The small-angle X-ray data show, that in the LCD particles different density of packing of the (DNA-polycation) complexes is realized. The comparison of the X-ray data of the liquid-crystalline phases of (DNA-polyconidin) complexes formed under various conditions with the phase diagram, that reflects the polymorphism of the linear double-stranded DNA liquid crystals, demonstrates that the hexagonal mode of the LCD packing is existing in 0.15-0.4 M NaCl solutions, whereas in 0.4-0.55 M NaCl solutions-- the cholesteric one. As a result of specific spatial organization the cholesteric LCD possesses of an abnormal optical activity in the CD spectrum. The similar situation takes place in the case of another synthetic polycation--poly(2,5-ionen), whose chemical structure differs from that of polyconidin. Thus, the structural polymorphism of the (DNA-polyconidine) LCDs was evidenced. It means that change of NaCl concentration opens a gate to control the spatial packing of the molecules of (DNA-polycation) complexes in the particles of LCDs. The supposition about mechanism of formation of the DNA cholesteric liquid-crystalline state in the narrow interval of NaCl concentrations was suggested.     

A comparative X-ray diffraction and circular dichroism study of DNA compact particles formed in water-salt solutions, containing poly(ethylene glycol).

Comparative CD and X-ray diffraction studies of DNA compact particules which were obtained in PEG-containing water-salt solutions, have been carried out. Compact particles, formed from native DNA, produce a psi CD spectrum (characterized by a negative band at lambda-270 nm) and a small-angle X-ray diffraction pattern, which shows two reflections: I at 34-40 A and II at 80-90 A (together with its second-order reflection). Compact particules, formed from DNA molecules with partially disordered secondary structure, do not produce the psi CD spectrum and the reflection I, while the reflection II remains unchanged. It is suggested that the spacing of 34-40 A is associated with a side-by-side packing of DNA fragments in "microcrystallization' regions in compact particules and that such "microcrystallization' accounts for the generation of the psi CD spectrum.     

Localization of 28-kDa peroxiredoxin in rat epithelial tissues and its antioxidant properties

Peroxiredoxins are a novel family of antioxidant proteins that specifically prevent enzymes from metal-catalyzed oxidation. The localization of a member of the mono-cystein subfamily of peroxiredoxins, the 28-kDa protein, in different rat tissues and its antioxidant properties were investigated. By immunoblotting, the 28-kDa peroxiredoxin was found to be most highly concentrated in olfactory epithelium and present in all tissues tested (skin, lung, trachea, kidney, womb, and brain). Immunostaining with rabbit polyclonal antibody raised against the 28-kDa peroxiredoxin revealed the particularly high level of the 28-kDa peroxiredoxin immunoreactivity in air-contacting areas (apical regions and mucus of the olfactory and respiratory epithelium and skin epidermis), which are continually exposed to numerous air-borne reactive oxygen species. In the apical regions of the olfactory and respiratory epithelium, the 28-kDa-peroxiredoxin immunogold labeling outlined microvilli and cilia and was mainly located in sustentacular cells and in respiratory and goblet cells, as electron-microscopic analysis revealed. In skin epidermis, the 28-kDa peroxiredoxin immunoreactivity was confined to the granular layer and specifically concentrated in sebaceous glands of hair follicle. In situ hybridization with 33P-labeled antisense RNA probe revealed the expression of the 28-kDa peroxiredoxin mRNA in tissues with a high level of the 28-kDa peroxiredoxin immunoreactivity. Immunodepletion of the 28-kDa peroxiredoxin profoundly decreased the antioxidant activity of the olfactory tissue extract.     

Sorption of plasma proteins by fluorocarbon emulsions stabilized by various surfactants

It has been found in in vivo and in vitro experiments that, as a perfluorocarbon emulsion stabilized by Proxanol 268 comes in contact with blood plasma proteins, plasma proteins with molecular masses from 25 to 170 kDa and above are adsorbed on the surface of emulsion particles. Among the adsorbed proteins, fibronectin and fibrinogen were identified by immunoblotting. In in vivo experiments, during circulation in the blood flow, considerable amounts of plasma proteins are adsorbed on Proxanol-stabilized emulsion particles; the amount of adsorbed proteins increases with the time the particles are in the blood flow. Considerably lesser amounts of proteins are adsorbed during circulation in the blood flow on emulsion particles stabilized by egg yolk phospholipids, and their qualitative composition differs from the composition of proteins adsorbed on Proxanol-stabilized emulsion particles. A preliminary incubation of the Proxanol-stabilized emulsion with heparin decreases the amount of the adsorbed proteins and changes their qualitative composition.