Estudo da labilidade de Cu(II), Cd(II), Mn(II) e Ni(II) em substâncias húmicas aquáticas utilizando-se membranas celulósicas organomodificadas

In this work commercial filters papers were organomodified with tetraethylorthosilicate (TEOS) and 3-aminopropyltriethoxysilane (3-APTS), aiming at the development of a new analytical procedure for in-situ speciation of labile and inert metal species in aquatic systems. Parameters that exert influence on the metal lability such as pH, chelating time, concentration and characteristics of the organic matter were studied in the laboratory using tests for metal recuperation. The results showed slower kinetics for Cu ion than for Ni, Mn and Cd in the absence of aquatic humic substances (AHS). The relative lability observed for complexed metals in aquatic humic substances using organomodified filter papers was Cu>>Cd>Ni>Mn. The pH values, structural characteristics and concentration of AHS exert strong influence on the lability of the metals. The results obtained showed that the utilization of organomodified filter papers can be an interesting and promising alternative for in situ characterization of metal lability in aquatic systems.

Renal and antibacterial effects induced by myotoxin I and II isolated from Bothrops jararacussu venom

Bothrops jararacussu myotoxin I (BthTx-I; Lys 49) and II (BthTX-II; Asp 49) were purified by ion-exchange chromatography and reverse phase HPLC. In this work we used the isolated perfused rat kidney method to evaluate the renal effects of B. jararacussu myotoxins I (Lys49 PLA(2)) and II (Asp49 PLA(2)) and their possible blockage by indomethacin. BthTX-1 (5 mu g/ml) and BthTX-II (5 mu g/ml) increased perfusion pressure (PP; ct(120) = 110.28+/-3.70 mmHg; BthTX I = 171.28+/-6.30* mmHg; BthTX II = 175.50+/-7.20* mmHg), renal vascular resistance (RVR; ct(120) = 5.49+/-0.54 mmHg/ml.g(-1) min(-1); BthTX I = 8.62+/-0.37* mmHg/ml g(-1) min(-1); BthTX II=8.9+/-0.36* mmHg/ml g(-1) min(-1)), urinary flow (UF; ct(120)= 0.14+/-0.01 ml g(-1) min(-1); BthTX I=0.32+/-0.05* ml g(-1) min(-1); BthTX II=0.37+/-0.01* ml g(-1) min(-1)) and glomerular filtration rate (GFR; ct(120)=0.72+/-0.10 ml g(-1) min(-1); BthTX I=0.85+/-0.13* ml g(-1) min(-1); BthTX II=1.22+/-0.28* ml g(-1) min(-1)). In contrast decreased the percent of sodium tubular transport (%TNa+; ct(120)=79,76+/-0.56; BthTX I=62.23+/-4.12*; BthTX II=70.96+/-2.93*) and percent of potassium tubular transport (%TK+;ct(120)=66.80+/-3.69; BthTX I=55.76+/-5.57*; BthTX II=50.86+/-6.16*). Indomethacin antagonized the vascular, glomerular and tubular effects promoted by BthTX I and it's partially blocked the effects of BthTX II. In this work also evaluated the antibacterial effects of BthTx-I and BthTx-II against Xanthomonas axonopodis. pv. passiflorae (Gram-negative bacteria) and we observed that both PLA2 showed antibacterial activity. Also we observed that proteins Also we observed that proteins chemically modified with 4-bromophenacyl bromide (rho-BPB) decrease significantly the antibacterial effect of both PLA(2). In conclusion, BthTx I and BthTX II caused renal alteration and presented activity antimicrobial. The indomethacin was able to antagonize totally the renal effects induced by BthTx I and partially the effects promoted by BthTx II, suggesting involvement of inflammatory mediators in the renal effects caused by myotoxins. In the other hand, other effects could be independently of the enzymatic activity of the BthTX II and the C-terminal domain could be involved in both effects promoted for PLA(2). (C) 2005 Elsevier Ltd. All rights reserved.

Coeficientes de difusão de metais em materiais não convencionais (agarose e acetato de celulose) usados na técnica de difusão em filmes finos por gradientes de concentração

The DGT technique allows one to measure quantitatively free and labile metal species in aquatic systems. Nevertheless, for this approach, knowledge is required of the diffusion coefficients of the analytes in a diffusive layer. In this study, the diffusion coefficients of Hg(II), As(III), Mn(II), Mg(II), Cu(II), Cd(II) were determined in agarose gel and those of Ba(II), Cd(II), Cu(II), Mg(II), Mn(II) e Zn(II) in cellulose acetate membranes. These materials presented good performance and the reported results can be used as a data base for further DGT studies.