Fluorimetric determination of the levels of urinary neopterin and serum thiobarbituric acid reactive substances in the nonagenarians

Twelve self-sustaining nonagenarians, 10 women and two men, aged 94+/-3 years, and eight institutionalised nonagenarians, eight women, aged 91+/-1 year as well as 11 control subjects, seven women and four men, aged 84+/-5 years entered the study. Urinary neopterin, an indicator of systemic immune activation, and serum thiobarbituric acid reactive substances (TBARS), a marker of lipoperoxidation, were determined initially, and collection of the blood and urine samples was repeated at 3-month interval. Neopterin was measured in the urine specimens by reversed-phase high performance liquid chromatography. A C(18) reversed-phase column 3.3x150 mm, 5 mum-diameter packing Separon SGX was used. Potassium phosphate buffer (15 mmol l(-1), pH 6.4) at flow rate of 0.8 ml min(-1) was used as mobile phase. After centrifugation (5 min, 1300xg) and diluting 100 mul of urine specimens with 1.0 ml of mobile phase containing 2 g of disodium-EDTA per litre, a 20 mul sample was injected on a column. Neopterin was identified by its native fluorescence (353 nm excitation, 438 nm emission). Creatinine was determined by Jaffé kinetic reaction after dilution of sample 1:50 (v/v). The concentration of neopterin in urine was expressed as neopterin/creatinine ratio (mumol mol(-1) creatinine). TBARS were determined spectrofluorometrically using LS-5 spectrofluorimeter (excitation wavelength 528 nm, emission wavelength 558 nm) after extraction with n-butanol treatment with thiobarbituric acid. The significance of differences between nonagenarians and control group was examined by ANOVA-Kruskal-Wallis tests, using statistical software NCSS 6.0.21 (Kaysville, UT, 1996). The decision on significance was based on P=0.05. Urinary neopterin was significantly higher in institutionalised compared to self-sustaining subjects and controls (625+/-565 vs. 203+/-63 mumol mol(-1) creatinine, and 198+/-128 mumol mol(-1) creatinine, respectively, P=0.006). The serum TBARS were higher in both groups of nonagenarians (3.23+/-1.16 mumol l(-1) and 2.69+/-0.39 vs. 2.12+/-0.83 mumol l(-1) for the self-sustaining, institutionalised and controls, respectively, P=0.023). We conclude that the fluorimetric determinations of urinary neopterin and serum TBARS can be useful for the monitoring health status in the elderly patients.     

Abraham Model Expressions for Describing Water-to-Diethylene Glycol and Gas-to-Diethylene Glycol Solute Transfer Processes at 298.15 K

A gas chromatographic headspace analysis method was used to experimentally determine gas-to-liquid partition coefficients and infinite dilution activity dilution for 14 different aliphatic and cyclic hydrocarbons (alkanes, cycloalkanes, alkenes, alkynes), eight different aromatic compounds (benzene, alkylbenzenes, halobenzenes), five different chloroalkanes (dichloromethane, trichloromethane, 1-chlorobutane, 1,2-dichloropropane, isopropylbromide), tetrahydrofuran, butyl acetate, and acetonitrile dissolved in diethylene glycol at 298.15 K. Solubilities were also measured at 298.15 K for 31 crystalline nonelectrolyte organic solutes including several polycyclic aromatic hydrocarbons and substituted benzoic acid derivatives. The experimental results of the headspace chromatographic and spectroscopic solubility measurements were converted to gas-to-diethylene glycol and water-to-diethylene glycol partition coefficients, and molar solubility ratios using standard thermodynamic relationships. Expressions were derived for solute transfer into diethylene glycol from the calculated partition coefficients and solubility ratios. Mathematical correlations based on the Abraham model describe the observed partition coefficient and solubility data to within 0.14 log₁₀ units (or less).     

Easily manufactured TiO2 hollow fibers for quantum dot sensitized solar cells

TiO(2) hollow fibers with high surface area were manufactured by a simple synthesis method, using natural cellulose fibers as template. The effective light scattering properties of the hollow fibers, originating from their micron size, were observed by diffuse reflectance spectroscopy. In spite of the micrometric length of the TiO(2) hollow fibers, the walls were highly porous and high surface area (78.2 m(2) g(-1)) was obtained by the BET method. TiO(2) hollow fibers alone and mixed with other TiO(2) pastes were sensitized with CdSe quantum dots (QDs) by Successive Ionic Layer Adsorption and Reaction (SILAR) and integrated as a photoanode in quantum dot sensitized solar cells (QDSCs). High power conversion efficiency was obtained, 3.24% (V(oc) = 503 mV, J(sc) = 11.92 mA cm(-2), FF = 0.54), and a clear correspondence of the cell performance with the photoanode structure was observed. The unique properties of these fibers: high surface area, effective light scattering, hollow structure to facile electrolyte diffusion and the rather high efficiencies obtained here suggest that hollow fibers can be introduced as promising nanostructures to make highly efficient quantum dot sensitized solar cells.     

Electrical bending instability in electrospinning visco‐elastic solutions

The electrical bending instability in charged liquid jets is the phenomenon determining the process of electrospinning. A model of this phenomenon is lacking however, mostly due to the complicated interplay between the viscosity and elasticity of the solution. To investigate the bending instability, we performed electrospinning experiments with a solution of polyethylene oxide in water/ethanol. Using a fast camera and sensitive multimeter, we deduced an experimental dispersion relation describing the helix pitch length as a function of surface charge. To understand this relation, we developed a theoretical model for the instability for a wide range of visco‐elastic materials, from conducting to nonconducting. The theoretical dispersion relation shows good agreement with the experimental results. Using the new model, we find that the elastic tension in the visco‐elastic threads plays an important role in triggering the instability. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1036–1042     

Transition metal ions-doped polyaniline/graphene oxide nanostructure as high performance electrode for supercapacitor applications

Journal of Solid State Electrochemistry - Polyaniline/graphene oxide (PANI/GO) co-doped with Zn2+ and Fe3+ was synthesized via a simple and low cost one-step chronoamperometry method on stainless...     

Fluorometric assay of lipoperoxides and chromatographic analysis of alpha-tocopherol and fatty acids as biomarkers of risk from coronary atherosclerosis

There has been growing interest in the quantitative determination of biochemical predictors of atherogenesis. The aim of the present study was to investigate association of lipoperoxidation biomarkers known to be pro-atherogenic (thiobarbituric acid reactive substance activity, TBARS) or anti-atherogenic (alpha-tocopherol) with the fatty acid status, and relate it to the coronary artery disease (CAD) as assessed by coronary angiography in patients with stable angina pectoris. We found that serum lipoproteins and TBARS did not differ significantly. However there was significant correlation of TBARS with total vitamin E (P=0.02) and vitamin E in very low-density lipoprotein (VLDL) (P=0.02) and low-density lipoprotein (LDL) (P=0.01), with LDL-linoleic acid (P=0.01), and high-density lipoprotein-linoleic acid (P=0.02). There was significant correlation of total vitamin E (P=0.01) and VLDL-vitamin E (P=0.01) with the degree of CAD. We conclude that TBARS and alpha-tocopherol could not be evaluated as biomarkers for the severity of CAD among the patients with stable angina pectoris.     

Development and validation of HPLC method for the determination of α-tocopherol in human erythrocytes for clinical applications

In this work, a simple isocratic reversed-phase HPLC method for determination of alpha-tocopherol in human erythrocytes has been developed and validated. After separation of plasma the erythrocytes were washed three times with 0.9% sodium chloride containing 0.01% butylated hydroxytoluene (BHT) as antioxidant and then were diluted 1:1 (v/v) with the same solution. In the liquid-liquid extraction (LLE) procedure, 2500 microL of n-hexane was added to 500 microL of erythrocytes. After 2 min this mixture was deproteinized by addition of cool ethanol (500 microL, 5 min) denatured with 5% methanol containing alpha-tocopherol acetate (20 micromol L(-1)), as internal standard, and then extracted for 5 min by vortex mixing. After centrifugation (10 min, 1600xg) an aliquot (2000 microL) of the clean extract was separated and evaporated under nitrogen. The residue was dissolved in 400 microL methanol and analysed by reversed-phase HPLC on a 4.6 mmx150 mm, 5 microm Pecosphere C18 column; the mobile phase was 100% methanol, flow rate 1.2 mL min(-1). The volume injected was 100 microL and detection was by diode-array detector at a wavelength of 295 nm. The extraction recovery of alpha-tocopherol from human erythrocytes was 100.0+/-2.0%. The detection limit was 0.1 micromol L(-1) and a linear calibration plot was obtained in the concentration range 0.5-20.0 micromol L(-1). Within determination precision was 5.2% RSD (n=10), between determination precision was 6.1% RSD (n=10). The method was applied successfully in a clinical study of patients with acute pancreatitis and for determination of the reference values in the healthy Czech population.     

Oxidation of bisnaphthols to spironaphthalenones,revisited

Bis(2‐hydroxy‐1‐naphthyl)methane derivatives have been efficiently converted to their corresponding spirans through three methods, i.e. oxidation by TCCA under mild reaction conditions, Ph₃Bi catalyzed air oxidation, and by electrochemical reaction. The first two methods are diastereoselective and give either of the two possible diastereomers, while the electrochemical method produces equal amounts of these diastereomers.     

Silica Sulfuric Acid and Al(HSO4)3: As Efficient Catalysts for the Formylation of Alcohols by Using Ethyl Formate under Heterogeneous Conditions

A mixture of ethyl formate and a catalytic amount of silica sulfuric acid or Al(HSO₄)₃ as suitable formylating systems can formylate various alcohols to their corresponding formate ester derivatives under mild, nearly neutral and heterogeneous conditions at room temperature with good to excellent yields.