Relationship between Cu and Zn extractable foliar contents and BCR sequential extraction in soil treated with organic amendments.

The application of organic wastes to soils, such as municipal solid waste compost (MSWC) or treated urban sewage sludge (USS) is a current practice for maintaining soil organic matter, reclaiming degraded soils and supplying plant nutrients. Since USS and MSWC may contain organic contaminants, heavy metals or pathogens, this practice represents a potential problem to the environment. In the case of heavy metals both bioavailability and toxicity seems to be critically dependent on the chemical form of the element. In this work, a pot experiment was carried out with different levels of MSWC and USS, as well as an inorganic solution of Cu and Zn. The aim was to obtain information about their bioavailability, mobility and toxicity and correlation among the different soil extracted fractions (F1--Exchangeable metal associated with carbonated phases, F2--Reducible metal or associated with Fe and Mn oxides, F3--Oxidizable metal bound to organic matter) with the Cu and Zn foliar (Cu(F) and Zn(F)) and pseudo totals contents (Cu(Ptotal) and Zn(Ptotal)), using the BCR sequential and aqua regia extraction procedure. Both of these methods were adequate to predict the Cu and Zn available to the plant, as high values on the Cu(F)-Cu(sigma123), Cu(F)-Cu(Ptotal), Zn(F)-Zn(sigma123) and Zn(F)-Zn(Ptotal) correlations were verified. Copper bounded mainly to F3, while Zn bounded to F1, F2 and F3 fractions and the regression analysis revelled that Cu and Zn ryegrass absorption were made mainly on F1 and F3 for Cu and F1 for Zn.

Human heart-infiltrating T-cell clones from rheumatic heart disease patients recognize both streptococcal and cardiac proteins.

BACKGROUND: beta-Hemolytic streptococcal infection in developing countries still causes thousands of causes of rheumatic heart disease, demanding surgical valve correction. Antigenic mimicry between self and streptococcal components has been proposed as the triggering factor leading to autoimmunity in individuals with genetic susceptibility. Although heart streptococcal-M protein cross-reactive antibodies have been demonstrated, heart tissue damage seems to be T lymphocyte-dependent. We studied the infiltrating T lymphocytes in rheumatic heart lesions with the aim of understanding the role of cellular immune response at the site of the lesions. METHODS AND RESULTS: We obtained 107 T-cell clones from surgical fragments of cardiac tissue from four rheumatic heart disease patients. We tested their capacity to recognize streptococcal M protein-derived synthetic peptides and heart proteins. We found eight infiltrating T-cell clones from all four patients that simultaneously recognize streptococcal M and heart proteins. Among the M-protein sequences tested, only synthetic peptides corresponding to regions 1 through 25, 81 through 103, and 163 through 177 were simultaneously recognized with heart protein fractions. Interestingly, regions 81 through 103 and 163 through 177 have been known to bear heart cross-reactive epitopes at the antibody level. Five of these clones are CD4+, and one is CD8+. CONCLUSIONS: The presence of heart-M protein cross-reactive T-cell clones in rheumatic heart lesions suggests their direct involvement in the pathogenesis of this disease. The dissection of protective and pathogenic epitopes of streptococcal M protein is an important step in allowing the development of a safe anti-streptococcal synthetic vaccine.