Analogs of squalene and oxidosqualene inhibit oxidosqualene cyclase of <Emphasis Type="Italic">Trypanosoma cruzi</Emphasis> expressed in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

Recently, a number of inhibitors of the enzyme oxidosqualene cyclase (OSC; EC 5.4.99.7), a key enzyme in sterol biosynthesis, were shown to inhibit in mammalian cells the multiplication of Trypanosoma cruzi, the parasite agent of Chagas’ disease. The gene coding for the OSC of T. cruzi has been cloned and expressed in Saccharomyces cerevisiae. The expression in yeast cells could be a safe and easy model for studying the activity and the selectivity of the potential inhibitors of T. cruzi OSC. Using a homogenate of S. cerevisiae cells expressing T. cruzi OSC, we have tested 19 inhibitors: aza, methylidene, vinyl sulfide, and conjugated vinyl sulfide derivatives of oxidosqualene and squalene, selected as representative of different classes of substrate analog inhibitors of OSC. The IC₅₀ values of inhibition (the compound concentration at which the enzyme is inhibited by 50%) are compared with the values obtained using OSC of pig liver and S. cerevisiae. Many inhibitors of pig liver and S. cerevisiae OSC show comparable IC₅₀ for T. cruzi OSC, but some phenylthiovinyl derivatives are 10–100 times more effective on the T. cruzi enzyme than on the pig or S. cerevisiae enzymes. The expression of proteins of pathogenic organisms in yeast seems very promising for preliminary screening of compounds that have potential therapeutic activity.     

The Seniors’ Outdoor Survey (SOS Tool): comparing ratings and reliability between Italy and the USA

To test applicability of an environmental assessment instrument in new settings, the ratings and reliability of the SOS Tool were compared in diverse settings with a similar climate: Milan, Italy; and Bryan/College Station, Texas, USA. This instrument evaluates physical environment support for outdoor usage by residents at senior facilities. Two trained raters assigned ratings (using a 1–7 scale) to the 60 instrument items at each setting (Italy: 94 outdoor spaces, 67 facilities; US: 22 outdoor spaces, 12 facilities). Overall mean ratings were similar across both sites (6% difference), and three of the five domains had comparable mean ratings. Mean inter-rater reliability was good in both settings but higher in Italy (ICC = .97 versus .82). Despite geographic/cultural differences, mean ratings for most items and domains were surprisingly similar between Italy and the US. This finding, and the high inter-rater reliability found in both settings, suggest this instrument may be useful in a wide range of settings.     

Electrochemical and corrosion behaviour of work-hardened commercial austenitic stainless steels in acid solutions

This paper describes the results of a study concerning the electrochemical and corrosion behaviour of AISI Types 304L and 316L stainless steels, cold worked under various conditions, in 1M H₂SO₄ and in 0.1M HCl de-aerated solutions. Anisotropic behaviour of specimen surfaces with different orientations to the direction of deformation has been observed. Stress corrosion cracking of the deformed steels can occur at room temperature in the 0.1M HCl solution both in the active and transition regions of the polarization curves.     

Bryophytes as indicators of trace metals pollution in the River Brenta (NE Italy)

The performance of aquatic bryophytes for detecting metal pollution was tested along the River Brenta, in NE Italy. Nine sampling sites were selected, three of them along short tributaries with no anthropic influence upstream, the others along the main bed of the river. Two sites were deliberately placed downstream from a previously known pollution focus. The multivariate analysis (classification and ordination) of the matrix of 10 metals and 38 samples revealed: (i) a good discrimination between 'clean' and potentially polluted sites; (ii) two contamination syndromes, one by As and, to a lesser degree, Pb, and the other by Cr, due to agricultural and industrial activities, respectively; and (iii) the previously known pollution focus was clearly detected. The magnitude of contamination was estimated by means of a comparison between local backgrounds and concentrations of metals measured. The distance of aquatic bryophytes from the center of the river was negatively correlated with metal concentrations, which suggests that this factor should be taken into account in the implementation of sampling protocols.     

Influence of the operating conditions on the electrochemical disinfection process of natural waters at BDD electrodes

Results are reported of an investigation of the oxidation products formed during electrolyses of aqueous solutions of NaCl, in which the initial concentration of chloride ions was maintained at levels normally present in natural waters. The Design of Experiments (DOE) technique has been used effectively to plan a framework of experiments, in which the main operative parameters: current density, electrolyte stirring rate, and cell geometry, were varied at two levels. Their effects, as well as their possible interactions have been evaluated on the yield of chloride oxidation and on the selectivity of the reaction towards the formation of hypochlorite.