Differential diagnosis of ascites in internal medicine: clinical case.

Ascites and hydrothorax may be the symptoms of congestive heart failure and do not always reflects presense of the decompensated liver cirrhosis. Clinical examination of patient with chronic hepatitis C which cyanosis of the lips, cervival veins pulsation, a triple heart rhythm indicated on pathology of the heart (constrictive pericarditis), which was confirmed by instrumental methods. Congestive heart failure has lead to the congestive liver in a young female patient. Regression of all the symptoms of heart failure occurred after surgical treatment (pericardectomy).

pH-induced changes in electronic absorption and fluorescence spectra of phenazine derivatives.

The visible electronic absorption and fluorescence spectra as well as fluorescence polarization degrees of imidazo-[4,5-d]-phenazine (F1), 2-methylimidazo-[4,5-d]-phenazine (F2), 2-trifluoridemethylimidazo-[4,5-d]-phenazine (F3), 1,2,3-triazole-[4,5-d]-phenazine (F4) and their glycosides, imidazo-[4,5-d]-phenazine-N1-beta-D-ribofuranoside (F1rib), 1,2,3-triazole-[4,5-d]-phenazine-N1-beta-D-glucopyranoside (F4gl), were investigated in aqueous buffered solutions over the pH range of 0-12, where the spectral transformations were found to be reversible. The effects of protonation and deprotonation on spectral properties of these dyes were studied. We have determined the ranges of pH, where individual ionic species are predominant. In aqueous buffered solutions the fluorescence was found only for neutral species of F1, F1rib, F2, and F4gl dyes, whereas for the ionic forms of these dyes, as well as for F3 and F4 ones, the fluorescence has not been detected. The concentrational deprotonation pKa values were evaluated from experimental data. It was shown that donor-acceptor properties of the substituent group in the second position of the pentagonal ring substantially affect the values of the deprotonation constants and the character of protonation for chromophore. The substitution of a hydrogen atom in the NH-group by the sugar residue blocks the formation of the anionic species, and results in enhancement of the dye emission intensity. The steep emission dependence for F1 and F1rib over pH range of 0-7 with intensities ratio of IpH 7/IpH 1=60 allows us to propose them as possible indicator dyes in luminescence based pH sensors for investigation of processes accompanied by acidification, e.g. as gastric pH-sensors. A comparative analysis of the studied dyes has shown that F4gl is the most promising compound to be used as a fluorescent probe for investigation of molecular hybridization of nucleic acids.

Absorption and fluorescent spectral studies of imidazophenazine derivatives.

Absorption and fluorescent spectra as well as fluorescence polarization degree of imidazo-[4,5-d]-phenazine (F1) and its two modified derivatives, 2-trifluoridemethylimidazo-[4,5-d]-phenazine (F2) and 1,2,3-triazole-[4,5-d]-phenazine (F3), were investigated in organic solvents of various polarities and hydrogen bonding abilities. Extinction coefficients of F2 and F3 are increased, their fluorescence Stokes shifts are reduced in comparison with those for unmodified imidazophenazine. For F3 a red shift of the longwave absorption band is observed by 15-20 nm. Modifications of imidazophenazine have led to a sufficient increase of fluorescence polarization degrees that enables to use F2 and F3 as promising fluorescent probes with polarization method application. The configuration, atomic charge distribution and dipole moments of the isolated dye molecules in the ground state were calculated by the DFT method. The computation has revealed that ground state dipole moments of F1, F2, and F3 differ slightly and are equal to 3.5, 3.2, and 3.7D, respectively. The changes in dipole moments upon the optical excitation for all derivatives estimated using Lippert equation were found to be Deltamu = 9 D. The energies of the electronic S1<--S0 transition in solvents of different proton donor abilities were determined, and energetic diagram illustrating the substituent effect was plotted. For nucleoside analogs of these compounds, covalently incorporated into a nucleotide chain, we have considered a possibility to use them as fluorescent reporters of hybridization of antisense oligonucleotides, as well as molecular anchors for its stabilization.

Conformational transitions and aggregation in poly(dA)-poly(dT) system induced by Na+ and Mg2+ ions.

Effects of Mg(2+) ions on thermally induced conformational transitions in the synthetic poly(dA).poly(dT) and poly(dA).2poly(dT) were studied in the buffered solutions (pH 6.9), containing 0.1 or 1M NaCl at polynucleotide concentration of 0.1-0.3mM (in nucleic bases). The experiments consist of measurements of the UV absorption and intensity of conventional visible static light scattering. The diagram of conformational transitions in the poly(dA)-poly(dT)-Mg(2+) system was constructed on a basis of experimental data obtained. Anomalously strong light scattering, like critical opalescence, has been revealed at 0.1M NaCl and [Mg(2+)]>/=20mM in the melting range of both polynucleotides, which eventually disappeared after the completion of polymer strands separation. The effect presumably is caused by a fluctuation process of polymer strands complexing which arises at a certain concentration of Mg(2+) ions.

Anchorage of oligonucleotide hybridization by tethered phenazine nucleoside analogue.

UV absorption and fluorescence techniques with a thermal denaturation procedure were used in studies of the anchorage of an oligonucleotide hybridization by a covalently tethered nucleoside analogue of an intercalating imidazophenazine derivative (Pzn). The formation by the (dT)(10)Pzn conjugate of the duplex complex with (dA)(15) and the triplex complex with (dA)(15) or poly(dA).poly(dT) was studied in buffered solutions with 0.11 and/or 1M sodium ions at the oligomer strand concentration of 10 microM. Because of the Pzn emission sensitivity to the interaction with adenine bases, a fluorescence technique was found to be effective in the detection of melting transitions. The attached Pzn substantially enhanced the thermal stability of complexes formed by (dT)(10) because of the intercalation mechanism, which increased the temperature of half-dissociation of the duplex by 10-12 degrees C and of the triplexes by approximately 13 degrees C. With the assumption of a two-state model of transition, the thermodynamic parameters for duplex formations were derived. The investigated variant of conjugation has a certain advantage over the widely used attachment via a flexible linker, consisting of a predetermined location of the Pzn chromophore in target sequences that makes it useful as a fluorescent reporter of the hybridization correctness. Molecular modeling was used to construct the geometries of the intercalation sites that turned out to be in conformity with the behavior of the Pzn fluorescence.

Fluorescence and binding properties of phenazine derivatives in complexes with polynucleotides of various base compositions and secondary structures.

The interactions of two phenazine derivatives, one with a neutral chromophore (glycoside) and the other with a cationic one (quaternary salt), with various synthetic single- and double-stranded polynucleotides and natural DNA were studied by fluorescence techniques, conducting measurements of steady-state fluorescence intensity and polarization degree as well as fluorescence lifetime. These dyes show fluorescence quenching upon intercalation into the GC sequences of the double-stranded nucleic acids and an increase in fluorescence emission and lifetime upon incorporation into the AT and AU sequences. GC base pairs in continuous deoxynucleotide sequences were found to be preferred as binding sites for both phenazines, in contrast to AT base pairs. On the contrary, the continuous ribonucleotide GC sequence binds the phenazines more weakly than does the AU sequence. With regard to the interaction of the phenazines with single-stranded polynucleotides, a stacking interaction of the dye chromophores with the nucleic bases was observed. In that case the guanine residue quenches the cationic phenazine fluorescence, while the stacking interaction with the other bases results in an increase in the fluorescence quantum yield. Unlike the cationic dye, the fluorescence of the neutral phenazine was quenched by both purine bases.