A. A. S. C. Machado

Sediments as monitors of heavy metal contamination in the Ave river basin (Portugal): multivariate analysis of data.

The concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) were determined in river sediments collected at the Ave river basin (Portugal) to obtain a general classification scenery of the pollution in this highly polluted region. Multivariate data analysis techniques of clustering, principal components and eigenvector projections were used in this classification. Five general areas with different polluting characteristics were detected and several individual heavy metal concentration abnormalities were detected in restricted areas. A good correlation between the overall metal contamination determined by multivariate analysis and metal pollution indexes for all sampling stations was obtained. Some preliminary experiments showed that the metal concentrations normalised to the volatile matter content in the sediment fraction with grain size <63 microm seems to be an adequate method for assessing metal pollution.

Defibrotide as salvage therapy for refractory veno-occlusive disease of the liver complicating allogeneic bone marrow transplantation.

A 30-year-old woman developed veno-occlusive disease of the liver during an allogeneic BMT for acute leukemia. Treatment with recombinant human tissue plasminogen activator and heparin resulted in an incomplete and transient response followed by progressive disease. The patient was then given defibrotide (DF), a mammalian tissue-derived polydeoxyribonucleotide developed for the treatment of a number of vascular disorders, which has thrombolytic and anti-thrombotic properties. No significant bleeding or other major toxicities were observed during treatment and she made a full recovery. At 6 months after the onset of VOD her liver function tests and color flow Doppler ultrasound scan are normal. Our experience supports the preliminary results already obtained with DF. Its efficacy should be evaluated in a prospective randomized fashion.

Characterization of the Acid-Base Properties of Humic Substances by Chemometric Analysis of Synchronous Fluorescence and pH Potentiometric Data

Abstract A procedure for the analysis of the acid-base characteristics of humic substances based on a self-modeling analysis of synchronous fluorescence spectra, collected at varying pH, and on a non-linear least squares adjustment of potentiometic pH data, is described. The data analysis methodology consists of two steps: first, the number of acid-base systems and the corresponding spectra and distribution diagrams are calculated by evolving factor analysis (EFA) with concentration constraints of the spectroscopic data; second, the potentiometric data is analyzed by a standard non-linear least square procedure using as fixed parameters the number of components and their pKas, determined in the first step of the analysis. As an example, for a sample of marine fulvic acids studied at pH between 2 and 11, four acid-base systems were found with average pKas: 3.1, 4.8, 8.0 and 10.0. The concentrations of the corresponding systems were: 2.55(5), 1.95(7), 0.14(4) and 1.8(3) meq/g.