Oxidation Chemistry of 3,7-Dimethylxanthine - a Central Behavioural Stimulant at Solid Electrodes

The electrochemical oxidation of 3,7-dimethylxanthine has been studied in the pH range 2.1-10.7 at pyrolytic graphite, platinum and glassy carbon electrodes. The electrooxidation of 3,7-dimethylxanthine at solid electrodes proceeds in a single 4e, 4H+ pH dependent step to give a diimine species which decomposes in Chemical followup steps. The UV absorbing intermediate generated during electrooxidation of 3,7-dimethylxanthine decayed approximately at the same rate as that of xanthine and followed the first order kinetics. The products of electrooxidation of 3,7-dimethylxanthine were characterized and a reaction scheme is suggested to explain their formation. The effect of introducing methyl groups into the electrooxidation of xanthine is also presented

Oxidation Chemistry of 3,7-Dimethylxanthine - a Central Behavioural Stimulant at Solid Electrodes

The electrochemical oxidation of 3,7-dimethylxanthine has been studied in the pH range 2.1-10.7 at pyrolytic graphite, platinum and glassy carbon electrodes. The electrooxidation of 3,7-dimethylxanthine at solid electrodes proceeds in a single 4e, 4H+ pH dependent step to give a diimine species which decomposes in Chemical followup steps. The UV absorbing intermediate generated during electrooxidation of 3,7-dimethylxanthine decayed approximately at the same rate as that of xanthine and followed the first order kinetics. The products of electrooxidation of 3,7-dimethylxanthine were characterized and a reaction scheme is suggested to explain their formation. The effect of introducing methyl groups into the electrooxidation of xanthine is also presented

Adsorption studies on the removal of hexavalent chromium from aqueous solution using a low cost fertilizer industry waste material

Low cost fertilizer industry waste material called carbon slurry, produced in generators of fuel oil based industrial generators was converted into an effective and efficient adsorbent for the removal of hexavalent chromium (VI) from aqueous solutions.The waste was chemically treated, activated, characterized and used for the adsorption of chromium. The work involves batch experiments to investigate the effect of contact time, pH, temperature, concentration and adsorbent dose on the extent of adsorption by carbon slurry. The maximum adsorption was found at 70 min., 2.0 pH, 4.0 g/L dose, 303 K temperature. Maximum adsorption capacity (15.24 mg/g) of Cr(VI) on carbon slurry was observed at 100 mg/L initial Cr(VI ) concentration. Langmuir and Freundlich adsorption isotherm models were applied to analyze adsorption data, and both were found to be applicable to this adsorption system, in terms of relatively high regression values. Thermodynamic parameters showed that the adsorption of Cr(VI) onto carbon slurry was feasible, spontaneous and exothermic under studied conditions. Kinetics of adsorption was found to follow pseudo second order rate equation. Column studies have been carried out to compare these with the batch capacities. The recovery of Cr(VI) and chemical regeneration of the spent column have also been tried. In all, the results indicated that the adsorbent used in this work proved to be effective material for the treatment of chromium bearing aqueous solutions

Differential pulse voltammetric investigations of uric acid in aqueous and micelle systems

283-289Differential pulse voltammetric behaviour of uric acid has been studied in phosphate buffers of pH 2.3-11.2 at glassy carbon electrode. A well-defined 2e, 2H+,pH-dependent oxidation peak has been noticed and the conjugate base found as the electroactive species. Cationic surfactants have been found to significantly effect the Ep and ip. At concentrations below CMC, the change in Ep is predominantly due to adsorption effects, whereas at concentrations above CMC electrocatalysis and micellar catalysis shifted the Ep towards less positive potentials. The voltammetric behaviour in the presence of surfactants indicates that the 2e oxidation proceeds in two 1e steps and the formation of cationic free radical is suggested. The products of electrode reaction have been found to be the same in aqueous and micelle systems

Phospholipase C from two bacterial strains acts differently on pure phospholipids and membrane bound glycosylphosphatidylinositol (GPI) anchors

92-99Phospholipase C (PLC) was purified to homogeneity from the culture filtrate of Bacillus cereus (65-fold, 540 U/mg protein) and B. thuringiensis (76-fold, 306 U/mg protein) by conventional techniques of enzyme purification. The purified enzymes have the molecular mass of 34 kDa and 38 kDa respectively, as determined by SDS-PAGE. Both the PLCs exhibited identical sensitivity to <span style="mso-bidi-font-family:Arial;mso-bidi-language: HI">pH, temperature, cations, anions and inhibitors like glutathione and p-chloromercuribenzoate. PLC-Bc showed a preference for phosphatidylinositol, while PLC-Bt favoured phosphatidylcholine as the substrate. Although both the enzymes were able to hydrolyze pure phosphatidylinositol, distinct differences were observed in their activity on phosphatidylinositol-anchored membrane proteins. PLC-Bc cleaved and released alkaline phosphatase, a GPI-anchored marker enzyme from microsomal membranes to a greater extent, than PLC-Bt. Experiments with sperm membranes, followed by SOS-PAGE revealed that the pattern of proteins released from their GPI-anchors by PLC-Bc and PLC-Bt were dissimilar. Although some proteins were cleaved in common by both PLCs, some others including a prominent 57 kDa protein were resistant to PLC-Bt, but sensitive to cleavage by PLC-Bc. The type of modification in the GPI anchor, special environment on membranes, and relative charge of host plasma membrane to the charge of PLC may be the factors that are responsible for the differential action of two enzymes. </span

Blockade of Neutrophil's Chemokine Receptors CXCR1/2 Abrogate Liver Damage in Acute-on-Chronic Liver Failure.

Neutrophils serve as critical players in the pathogenesis of liver diseases. Chemokine receptors CXCR1 and CXCR2 are required for neutrophil chemotaxis to the site of inflammation/injury and are crucial in hepatic inflammatory response. However, key mechanism of neutrophil-mediated liver injury in acute-on-chronic liver failure (ACLF) remains highly elusive; which could be targeted for the development of new therapeutic interventions