Convolution-deconvolution cyclic voltammetric equilibria study on cadmium(II)-L-histidinate in aqueous solutions.

POLAG computer programme was employed for processing convoluted-deconvoluted cyclic voltammetric data to study cadmium(II)-L-histidinate system. This was performed in 0.1 mol/dm(3) NAClO(4) aqueous solution at different pH's at 298K. The results show that the reduction of cadmium(II) and its complexes proceeds via a reversible and diffusion-controlled wave of two electrons at the entire range of pH. The system was studied at two ranges of pH (6.73-7.44 and 8.53-8.92). It was evident that the system at the first range of pH is well described by the presence of a mixture of binary complexes, [Cd(HisO.H)], [Cd(HisO.H(2))(2)] and a ternary one [Cd(HisO.H)(HisO.H(2))]. For the second pH range, it was revealed that the most likely model corresponds to the presence of a mixture of [Cd(HisO)(2)] and [Cd(OH)] species. The overall stability constants were computed. The structure of the detected complexes was discussed on the basis of ligating sites of histidine.

Potentiometric determination of the dissociation constants of L-histidine, proline and tryptophane in various hydroorganic media.

The dissociation constant values of L-histidine, proline and tryptophane were determined at 25 +/- 0.1 degrees C by potentiometric pH titration in pure water and different hydroorganic solvent media. The organic solvents used were methanol, ethanol, N,N-dimethylformamide, dimethyl sulfoxide, acetone and dioxane. Initial estimates of the dissociation constant values of the different amino acids studied have been refined with ESAP2M computer program. It was observed that changing the medium permittivity as the solvent is enriched in methanol or ethanol has little influence on the pK*(a) values of the amino acids studied. The results obtained are discussed in terms of average macroscopic properties of the mixed solvents and the possible variation in microheterogeneity of the salvation shells around the solute.

Calcium and phosphorus metabolic changes in children with hepatic bilharziasis.

Investigations were done to study the calcium and phosphorus metabolic changes in 35 children with hepatic bilharziasis, of whom 12 were ascitic. Thirteen normal children served as controls. Despite a normal serum level of both calcium and inorganic phosphate in the Bilharzial group, yet both were increased in urine. The mean values obtained from the ascitic fluid were 70% and 90.2% of their serum levels, respectively. The corrected creatinine clearance was significantly diminished, while PEI was significantly increased, and the % TRP significantly decreased, with still a more marked decrease in the ascitic cases. Following a phosphate lead the serum inorganic phosphate level showed a significantly more rapid lowering in both bilharzial groups, as compared to the control group. On the other hand bilharzial cases responded to the intravenous calcium load by a significant retention of calcium in the serum.