New Experimental Models of Retinal Degeneration for Screening Molecular Photochromic Ion Channel Blockers.

Application of molecular photochromic ion channel blockers to recover the visual function of a degenerated retina is one of the promising trends in photopharmacology. To this day, several photochromic azobenzene-based compounds have been proposed and their functionality has been demonstrated on cell lines and knockout mouse models. Further advance necessitates testing of the physiological activity of a great number of new compounds. The goal of this study is to propose animal models of photoreceptor degeneration that are easier to obtain than knockout mouse models but include the main features required for testing the physiological activity of molecular photoswitches. Two amphibian-based models were proposed. The first model was obtained by mechanical deletion of the photoreceptor outer segments. The second model was obtained by intraocular injection of tunicamycin to induce the degeneration of rods and cones. To test our models, we used 2-[(4-{(E)-[4-(acryloylaminophenyl]diazenyl}phenyl)amino]-N,N,N-triethyl-2-oxoethanammonium chloride (AAQ), one of the compounds that have been studied in other physiological models. The electroretinograms recorded from our models before and after AAQ treatment are in agreement with the results obtained on knockout mouse models and reported in other studies. Hence, the proposed models can be used for primary screening of molecular photochromic ion channel blockers.

Analysis of Immunogenicity of Intracellular CTAR Fragments of Epstein-Barr Virus Latent Phase Protein LMP1.

Intracellular fragments of latent phase protein LMP1 of Epstein-Barr virus, denoted as CTAR1/2/3, can trigger a variety of cell cascades and contribute to the transforming potential of the virus. Generation of recombinant proteins CTAR1/2/3 is expected to yield more ample data on functional and immunogenic characteristics of LMP1. We created genetic constructs for prokaryotic expression of LMP1 CTAR fragments and selected optimal conditions for their production and purification. Using a new library of LMP1 CTAR fragments, we carried out epitope mapping of a diagnostic anti-LMP1 antibody S12. Analysis of polyclonal serum antibodies from mice immunized with full-length LMP1 confirmed immunogenicity of CTAR elements comparable with that of full-length protein.

Mathematical model of polymerase chain reaction with temperature-dependent parameters.

The course of the real-time polymerase chain reaction (PCR) is determined by the temperature dependence of the kinetics of the component reactions, particularly the DNA strand hybridization. To investigate the effect of thermal processes on the reaction behavior, a mathematical model in which the variable rate constant of dissociation of "primer-single strand" complexes depends on temperature was proposed. The reaction medium temperature, which depends on time, was also introduced into the model. The proposed model of real-time PCR makes it possible to analyze different aspects of the reaction, which are important for the development of instruments and reagents for PCR.

[Current possibilities of clinical applications of breast tumors typing expression].

Whole-genome expression analysis methods significantly clarified contemporary breast cancer classification. Besides today clinical practice lacks the use of expression methods due to complexity of conduction, analysis and lack of clinical application. Further studies of breast cancer expression characteristics and clinical trials with stratification based of phonotypical features may improve the results of existing anticancer agents. Creation of limited clinically applicable test system, which incorporates all the specific breast cancer subtypes is currently needed.

[INFLUENCE OF OLEAMIDE OF WATER AND ION TRANSPORT IN THE OSMOREGULATORY ORGANS].

Application of oleamide (final concentration of 10 µM) at the skin basal surface of the frog, Rana temporaria L., augmented the short-circuit current (SCC) from 59.8 ± 2.5 to 78.2 ± 1.4 µA/cm2. Oleamide added to the serous membrane of the frog urinary bladder at a final dose of 1 µM induced more than 30-fold increase of osmotic permeability. The addition of arginine-vasotocin on the background of oleamide action further increased SCC across the isolated frog skin and osmotic permeability of the frog urinary bladder. Intraperitoneal injection of oleamide at a dose of 0.1 mM/100 g BW to water-loaded non-anesthetized Wistar rats decreased diuresis by 22%, enhanced solute-free water reabsorption and urinary sodium excretion by 31% and 55% respectively, but did not affect the renal potassium excretion. The results obtained provide evidence of similarity of oleamide and neurohypophyseal hormones effects on water and ion transport in epithelial cells of osmoregulatory organs in vertebrates.

[Magnetic nanoparticles and intracellular delivery of biopolymers].

The basic methods of intracellular delivery of biopolymers are present in this review. The structure and synthesis of magnetic nanoparticles, their stabilizing surfactants are described. The examples of the interaction of nanoparticles with biopolymers such as nucleic acids and proteins are considered. The final part of the review is devoted to problems physiology and biocompatibility of magnetic nanoparticles.

Rate equation approach to understanding the ion-catalyzed formation of peptides.

The salt-induced peptide formation is important for assessing and approaching schemes of molecular evolution. Here, we present experimental data and an exactly solvable kinetic model describing the linear polymerization of L-glutamic amino acid in water solutions with different concentrations of KCl and NaCl. The length distributions of peptides are well fitted by the model. Strikingly, we find that KCl considerably enhances the peptide yield, while NaCl does not show any catalytic effect in most cases under our experimental conditions. The greater catalytic effect of potassium ions is entirely interpreted by one and single parameter, the polymerization rate constant that depends on the concentration of a given salt in the reaction mixture. We deduce numeric estimates for the rate constant at different concentrations of the ions and show that it is always larger for KCl. This leads to an exponential increase of the potassium- to sodium-catalyzed peptide concentration ratio with length. Our results show that the ion-catalyzed peptides have a higher probability to emerge in excess potassium rather than in sodium-rich water solutions.

[Clinical significance of carriage of rare variants of connexin-26 genetic polymorphism in gastric cancer].

The authors present first results of investigations of the connexin-26 gene in DNA obtained from peripheral blood of 55 patients operated on for gastric cancer. Gastric cancer patients were found to have carriage of the Cx 26 gene that was reliably associated with the invasive ability of the tumor. Change of the connexin-26 gene in gastric cancer is evidence of an important role of intercellular gap junctions in the arising and development of gastric cancer.

[The role of gap junction communication in metastatic B16 melanoma in C57BL mice].

The study is concerned with the effects of non-specific blocking gap junction communication with oleamide as well as genesis and spreading of melanoma B16 metastases to the lung in mice C57B1. The blocking exerted no distinct influence on primary tumorigenesis but had a marked effect on metastatic spread. Oleamide treatment during tumor growth led to an increase in area covered by metastases. A correlation was established between metastatic frequency and dosage: 1 mg/kg was followed by an upsurge in frequency of secondary lung tumors while 10 mg/kg--by a drop.

[The scientific and clinical value of molecular genetic changes in the intercellular gap junctions observed in colon cancer]. / Znachenie molekuliarno-geneticheskikh izmenenii mezhkletochnykh shchelevykh kontaktov pri rake tolstoi kishki.

Colon cancer is one of the most widespread pathologies with high mortality due to recurrence and metastasis. The molecular methods of diagnosis, prognostication and biotherapy in colorectal cancer enjoyed a rapid progress during the recent decades. The hypothesis on the key role of impaired intercellular gap junctions in the onset and progression of malignant tumors is a promising trend in carcinogenesis research. We have recently discovered a variety of tumor-specific mutations of connexin 43 gene in advanced colorectal cancer (Oncogene. -2002.-Vol.21, No.32-pp.4992-4996), which confirms the above hypothesis in malignant tumor progression. We believe that further studies of connexins' mutation changes in tumor growth is a promising trend in research of its etiology and pathogenesis and in designing new methods of diagnostics and treatment of colonic and other gastrointestinal cancers.

[Circadian features of carcinogenesis of the large intestine induced by 1,2-dimethylhydrazine in rats]. / Tsirkadiannye osobennosti kantserogeneza tolstoi kishki, indutsirovannogo 1,2-dimetilgidrazinom u krys.

The study was concerned with comparison of carcinogenesis induced in the rat large intestine by 5 single doses of 1,2-dimethylhydrazine (DMH) 21 mg/kg injected at different circadian stages--either at 10 a.m. or 10 p.m. Evening injections were followed by significant decrease in incidence (from 91 to 75%) and size of tumor (27.2-15.5 mm2). Also, there were relatively fewer large tumors in the evening series.

Microvascular endothelium dysfunction in rats bearing 1,2-dimethylhydrazine-induced colon tumors.

Functional parameters (adhesivity, permeability, thrombogenicity and thromboresistance) of the mesenteric microvasculature endothelium in rats bearing 1,2-dimethylhydrazine (DMH) induced colon tumors were studied using a complex method, based upon computer-assisted microscopic video image processing. It was shown that paraneoplastic endothelial dysfunction in rat mesenteric microvessels is characterized by an increase in leukocyte adhesion to the endothelium, microvessel permeability and thrombogenic properties. It was demonstrated that the observed changes are the consequences of tumor growth and are related to tumor size and the duration of the process.

Microvascular endothelium dysfunction during growth of transplanted lymphosarcoma and glioma in rats.

The changes of endothelium functional parameters (adhesivity, permeability, thrombogenity and thromboresistance) in mesenteric microvasculature in rats with two transplanted tumors: fast-growing Pliss' lymphosarcoma (PLS) and slow-growing glioma-35 (G-35) were studied, using a complex method, based upon a computer-assisted microscopic video image processing. The endothelial dysfunction in mesenteric microvessels is characterized by the increase of leukocyte adhesion to the endothelial cells, microvessels permeability and their thromboresistance properties decrease in tumor-bearing rats. The observed changes are shown to be the nonspecific manifestation of the tumor process development. They are determined by the duration of the process development and are not dependent on the tumor node size.

[The effect of dexamethasone on the functional features in rats with Pliss lymphosarcoma transplant]. / Vliianie deksametazona na funktsional'nye svoistva mikrososudov u krys s limfosarkomoi plissa.

A computer-assisted method of video imaging the adhesive, permeability and thrombogenic properties of microvessels was used to study the effect of dexamethasone on the functional activity of the mesenteric microvascular endothelium in rats with Pliss' lymphosarcoma. Dexamethasone-21 Na-phosphate (0.1 mg/ml) was supplied to the desired mesenteric area and the necessary measurements were carried out. The latter showed that tumor growth was associated with microcirculation disturbances, namely, raised leukocyte adhesion to the mesenteric microvascular endothelium, microvascular permeability and thrombogenicity. Enhanced microvascular sensitivity to dexamethasone pointed to the important role played by changes in the adhesive properties of the endothelium among general paraneoplastic disorders of microcirculation.

[The microvascular permeability of the skin and mesentery in rats adapting to hypoxia]. / Pronitsaemost' mikrososudov kozhi i bryzheiki u krys pri adaptatsii k gipoksii.

Changes of the rat skin and mesenteric microvascular permeability for Na-fluorescine were studied during adaptation to intermittent hypobaric hypoxia. The data obtained revealed that the microvascular permeability increased on the 10 th day after the hypoxia and decreased within 25 days of hte adaptation to the hypoxia in both areas under study.