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The aim of the study was to evaluate genotoxic effects of Pirimor-50®, a pirimicarb-based formulation (50 % active ingredient), in human lymphocyte cultures and Vicia faba root meristems. Furthermore, the objective was to examine a combined influence of insecticide treatment with mammalian microsomal S9 and vegetal S10 metabolic fractions or S10 mix metabolic transformation extracts (after Vicia faba primary roots treatment with Pirimor-50®). We used sister chromatid exchange assay-SCE and measured cell cycle progression and proliferation (proportion of M1-M3 metaphases and replication index ratio-RI). Two processes were used for plant promutagen activation: in vivo activation-Pirimor-50®was applied for 4 h to the plant and then S10 mix was added to lymphocytes; and, in vitro activation-lymphocytes were treated with Pirimor-50®and S10 or S9 for 2 h. Direct treatment induced significantly higher SCE frequencies in meristems at 0.01 mg mL-1. In lymphocytes, significantly higher SCE was at 1 mg mL-1with decrease in RI and M1-M3 metaphase proportions at 0.5 mg mL-1and cell division stop at 2.5 mg mL1. S10 mix lymphocyte treatment showed significantly elevated SCE values at 2-2.5 mg mL-1, with cell death at 3 mg mL-1. Lymphocyte treatment with Pirimor-50®together with S9 or S10 showed slightly elevated SCE frequency but had a significant influence on RI decrease, with lowest values in S9 treatment. Since no data are available on the genotoxicity of Pirimor-50®, this study is one of the first to evaluate and compare its direct effect in two bioassays, animal and vegetal, and also the effect of plant and animal metabolism on its genotoxic potential.

This study evaluated direct and metabolic genotoxic effects caused by Lannate-90®, a methomyl-based formulation (90 % active ingredient), in human lymphocyte cultures using sister chromatid exchange assay (SCE). Two processes were used for the plant promutagens evaluation: in vivoactivation, applying the insecticide systemically in plants for 4 h and subsequently adding plant metabolites containing extracts to lymphocyte cultures; and in vitroactivation, where the insecticide was incubated with Vicia fabaS10 mix plus human lymphocyte culture. Direct treatment with the insecticide significantly increased SCE frequency in human lymphocytes (250-750 mgL−1), with cellular death observed at 1000 mgL−1concentration. Using the extracts of Vicia fabatreated with Lannate-90®to treat human lymphocytes, a dose-response relationship was observed. In lymphocyte cultures treated directly with the insecticide for 2 h, a negative response was obtained. When S10 mix was added, SCE frequency did not change significantly. Meanwhile, a mixture of S9 mammalian metabolic mix and Lannate-90®increased the SCE frequency, with an observed concentration-dependent response. Although Lannate-90®induced cellular death at the highest concentrations, it did not cause a delay in cell proliferation in any of the treatments, confirming its genotoxic action. This study is one of the first to evaluate and compare the direct effect of Lannate-90®in two bioassays, animal and vegetal, and the effect of plant and animal metabolism on its genotoxic potential.

Electroactive macroporous polyvinylidene fluoridecotrifluoroethylene membranes have been produced by solvent evaporation at room temperature, starting with a diluted solution of the copolymer in dimethylformamide. The pore architecture consists of interconnected spherical pores. This architecture is independent of the membrane thickness. The thickness of the membranes ranges from a few to several hundred µm, using spin coating and evaporation in static conditions, respectively. The pore structure is explained by a spinodal decomposition of the liquidliquid phase separation and crystallization in the copolymerrich phase.

The objective of this paper is to analyze the international settlement system and its implications for the development of a global telecommunications network in an industry scenario that is moving beyond international accounting rates. The international dimension of funding developing countries' universal service policies is then discussed. It is pointed out that increasing competition in international markets, diverting traffic flows and retail price collection from developing to rich countries could lower the total revenue that the former obtain from international services, even when the received net settlement payments increase. The expected international settlement reforms asked for by the ITU and the US federal regulator could also intensify this phenomenon. Therefore, our conclusion is that such reforms may require adequate safe-guards to deliver financial support to developing world network infrastructure, also considering the positive externalities accruing to rich countries.

The conditions for immobilizing the new L-aminoacylase-producing bacterial strain, Pseudomonas sp. BA2, by entrapment in κ-carrageenan gel, were investigated. The optimal gel concentration and cell load were determined. The addition of CoCl2 and N-acetyl-L-alanine to the immobilizing matrix enhanced L-aminoacylase activity. The enzymatic properties of immobilized Pseudomonas sp. BA2 were investigated. Enzyme activity in immobilized cells was optimal at a pH of 6·5 using 0·15 mol dm^-3 Tris–maleate buffer at 45°C. The presence of 0·7 mmol dm^-3 CoCl2 in the enzymatic reaction mixture improved L-aminoacylase activity. The immobilized cell preparation was used for the production of L-alanine from N-acetyl-DL-alanine in a batch reactor. Conversions of 100% were obtained using substrate concentrations ranging from 20 to 200 mmol dm^-3. The reactor production was 0·74 mol h^-1 g cell^-1 dm^-3 which is noticeably higher than that previously reported in the literature. © 1998 Society of Chemical Industry