Adsorption of haematoporphyrins on the planar bilayer membrane

Adsorption of haematoporphyrin derivatives with different hydrophobicities of peripheral groups on a planar bilayer lipid membrane (BLM) was studied in the dark and upon illumination by the visible light. Haematoporphyrin molecules were shown to adsorb on the BLM as anions. The adsorption changed the boundary potential at the membrane/water interface, in particular, it altered the potential in the diffuse part of the double layer outside the membrane and increased an additional unscreenable potential drop inside it. Illumination decreased the value of the negative potential drop due probably to the appearance of a positive charge in the haematoporphyrin macrocycle. The adsorption of haematoporphyrins affected the BLM conductivity induced by different ionophores, which can be explained by changes in membrane structure. Haematoporphyrin derivatives with higher hydrophobicities adsorbed deeper inside the membrane, caused greater changes in its structure and displayed a stronger photodynamic effect.     

Eukaryotic DNA topoisomerase and in vitro recombination between circular supercoiled plasmid DNA's in an in vitro system

Eukaryotic DNA topoisomerase II was shown to catalyze recombination between circular supercoiled plasmid DNAs in vitro. The results obtained are discussed with regard to the organization of eukaryotic chromosomes in the form of topologically independent domains (loops).     

Compressed sensing of complex-valued data

Compressed sensing (CS) is a recently proposed technique that allows the reconstruction of a signal sampled in violation of the traditional Nyquist criterion. It has immediate applications in reduction of acquisition time for measurements, simplification of hardware, reduction of memory space required for data storage, etc. CS has been applied usually by considering real-valued data. However, complex-valued data are very common in practice, such as terahertz (THz) imaging, synthetic aperture radar and sonar, holography, etc. In such cases CS is applied by decoupling real and imaginary parts or using amplitude constraints. Recently, it was shown in the literature that the quality of reconstruction for THz imaging can be improved by applying smoothness constraint on phase as well as amplitude. In this paper, we propose a general l_p minimization recovery algorithm for CS, which can deal with complex data and smooth the amplitude and phase of the data at the same time as well has the additional feature of using a separate sparsity promoting basis such as wavelets. Thus, objects can be better detected from limited noisy measurements, which are useful for surveillance systems.     

Separation and characterization of Na+,K(+)-ATPase containing vesicles

Na+,K(+)-ATPase was reconstituted in vesicles prepared by a dialysis method. Ion-exchange chromatography was used to obtain well characterized fractions from the inhomogeneous vesicle preparation. Lipid and protein content was determined by optical methods during the elution process. It was possible to separate fractions with distinct enzymatic and transport activities. A protocol was set up, which allowed to calculate the average number of 5-IAF labeled ion pumps per vesicle in the different fractions. The dependence of the number of protein molecules per vesicle was studied as function of the initial protein concentration added to the lipid solution before dialysis. The transport activity disappears completely at very low protein concentrations (3.3 micrograms protein per mg lipid). This observation is in favor of the proposal discussed in the literature, that the heterodimer (alpha beta)2 is the transport-active form of the Na+,K(+)-ATPase. The presented method can be applied to all reconstituted vesicle preparations in which the proteins can be labeled quantitatively with a fluorescence dye.     

The antioxidant properties of lycopene

The antioxidant properties of the carotenoid lycopene were compared in three different model oxidative systems. In egg yolk liposomes, in the presence of 2.5 mM FeSO4 and 200 mM ascorbate, lycopene, alpha-tocopherol, and beta-carotene inhibited the accumulation of lipid peroxidation products reacting with 2-thiobarbituric acid (TBARS) in a dose-dependent mode, with the concentration of half-inhibition being 80, 30 and 130 mM, respectively. In the liposomes subjected to illumination with a He-Ne laser (632.8 nm) at a dose of 10.5 J/cm2, in the presence of 32.5 micrograms/ml hematoporphyrin derivatives (Fotogem, NIOPIC, Russia) TBARS accumulated, and this effect was inhibited by lycopene, alpha-tocopherol, and dihydroquercetin with approximately equal efficiencies (the half-inhibition concentrations were 10(-5) mM). In both systems studied, sodium azide at a concentration of 10 mM inhibited the TBARS accumulation by no more than 20%. Apparently, the inhibitory action of not only alpha-tocopherol, but also beta-carotene and lycopene was the result of their antiradical action, rather than quenching of the singlet oxygen in an aqueous medium. The introduction of lycopene, as well as beta-carotene in liposomes subjected to Fe(2+)-induced lipid peroxidation decreased the chemiluminescence (CL) intensity at the stage of CL slow flash, with no essential influence on the lag period. These data suggest that the effect of lycopene on lipid peroxidation was the result of its interaction with free radicals rather than chelating ferrous ions. The antiradical activity of lycopene was also confirmed by the method of luminol photochemiluminescence (PCL). Lycopene increased the PCL lag period (L) and decreased the PCL amplitude (A), which implies its antiradical and SOD-like activity in this system.     

NMR spectroscopic elucidation of the structure of a glycerol teichoic acid-like O-specific polysaccharide of the bacterium Hafnia alvei strain PCM 1199

The structure of the acidic O-specific polysaccharide of a Gram-negative bacterium, H. alvei strain PCM 1199, was studied by NMR spectroscopy including two-dimensional correlation spectroscopy (COSY), total correlation spectroscopy (TOCSY), nuclear Overhauser effect spectroscopy (NOESY), 1H, 13C heteronuclear single-quantum coherence (HSQC), 1H, 13C heteronuclear multiple-bond correlation (HMBC), and one-dimensional 1H, 31P heteronuclear multiple-quantum coherence (HMQC) experiments. It was found that the polysaccharide contains D-galactose, 2-acetamido-2-deoxy-D-glucose, 4-acetamido-4,6-dideoxy-D-glucose, glycerol, and phosphate in the ratios 1:2:1:1:1, as well as O-acetyl groups in non-stoichiometric amounts. The polysaccharide is similar in structure to teichoic acids of Gram-positive bacteria and has the following structure of the repeating unit: 3)-beta-D-Galp-(1-->3)-alpha-D-GlcpNAc-(1-->3)-beta-D-Quip4NAc-(1- ->1)-Gro- 3-P-(O--> [formula: see text] beta-D-GlcpNAc [formula: see text] The O-specific polysaccharide of H. alvei PCM 1199 is structurally related to another teichoic acid-like O-specific polysaccharide of H. alvei PCM 1205 studied by us earlier.     

Hematoporphyrin derivative or phthalocyanine photosensitized hemolysis of erythrocytes under laser irradiation

Lower arch crowding and dimensions were measured on study models of 46 untreated subjects, 20 male and 26 female, at age 18 years (T1), 21 years (T2), and 28 years (T3), and the changes during the observation periods calculated. Only very small changes, few of them detectable clinically, were found. The findings are discussed in relation to the changes reported in untreated subjects in other age groups and in orthodontically-treated subjects after retention.     

Effect of carnosine and its components on free-radical reactions

This study compared the competency to stand trial (CST) of 108 juveniles (ages 7 to 16 years) and 145 adults (17 years or older) undergoing pretrial, court-ordered forensic psychiatric evaluations. Adults were superior on both global and specific competency abilities (p < .001). Clustered by age (<13, 13 and 14, 15 and 16 years old), preteens accused of crimes failed to meet a Dusky v. United States standard, while 13- and 14-year-olds displayed an equal mix of abilities and deficits. Mid-adolescents (ages 15 and 16) were equivalent to adults in CST abilities except in their knowledge about plea bargaining elements. The ramifications of CST in felony juvenile transfer to adult court as well as the needs for ecologically valid, empirically based CST research on adolescents is discussed.     

Biophysical study of the globular organisation of interphase chromosomes

The globular model of interphase chromosomes is studied using methods involving the statistical physics of polymers. An interphase chromatid is represented as a flexible chain of structural sub-units, or superdomains (SDs). Each SD is simulated as a number of chromatin fibre loops fixed at a nuclear matrix core. A chain of SDs is further folded in the nucleus in a compact conformation owing to volumetric interactions between SDs. The algorithm used is extended to incorporate the chain anchorage at different points. Excluded volume effects are taken into account in Monte Carlo simulation at both the SD and whole chromosome level. A variety of structures is observed in computer experiments. The simulation results correlate with the available experimental data.