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Examples of bioactive peptides derived from internal sequences of proteins are known for decades. The great majority of these findings appear to be fortuitous rather than the result of a deliberate and methodological-based enterprise. In the present work, we describe the identification and the biological activities of novel antimicrobial peptides unveiled as internal fragments of various plant proteins founded on our hypothesis-driven search strategy. All putative encrypted antimicrobial peptides were selected based upon their physicochemical properties that were iteratively selected by an in-house computer program named Kamal. The selected peptides were chemically synthesized and evaluated for their interaction with model membranes. Sixteen of these peptides showed antimicrobial activity against human and/or plant pathogens, some with a wide spectrum of activity presenting similar or superior inhibition efficacy when compared to classical antimicrobial peptides (AMPs). These original and previously unforeseen molecules constitute a broader and undisputable set of evidences produced by our group that illustrate how the intragenic concept is a workable reality and should be carefully explored not only for microbicidal agents but also for many other biological functions.

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Background. To compare Child Behavior Checklist (CBCL) findings for a large Brazilian general population sample with those for US children considering: (a) mean problem item ratings; (b) fit of the US-derived CBCL 8-syndrome model; (c) scale internal consistency measured by Cronbach's alphas; (d) effects of society, age, gender on CBCL problem scores; and (e) ability to discriminate referred from non-referred children. Methods. Parents of 1228 non-referred 6-to-11-year-olds from three different regions of Brazil and 247 referred 6-to-11-year-olds from one clinic rated their children's behavioural and emotional problems using the CBCL/6-18. Results. Results for mean item ratings and scale internal consistencies were very similar to those found in the US and in Uruguay. Confirmatory factor analysis indicated that Brazilian data showed the best fit to the US 8-syndrome model of all countries studied to date. Gender patterns were comparable to those reported in other societies, but mean problem scores for non-referred Brazilian children were higher than those for US children. Therefore, the CBCL discriminated less well between non-referred and referred children in Brazil than in the US. Conclusions. Overall, our findings replicated those reported in international comparisons of CBCL scores for 31 societies, thereby providing support for the multicultural robustness of the CBCL in Brazil.

Although the mechanism of action of antimicrobial peptides (AMPs) is not clear, they can interact electrostatically with the cell membranes of microorganisms. New ocellatin-PT peptides were recently isolated from the skin secretion of Leptodactylus pustulatus. The secondary structure of these AMPs and their effect on Leishmania infantum cells, and on different lipid surface models was characterized in this work. The results showed that all ocellatin-PT peptides have an α-helix structure and five of them (PT3, PT4, PT6 to PT8) have leishmanicidal activity; PT1 and PT2 affected the cellular morphology of the parasites and showed greater affinity for leishmania and bacteria-mimicking lipid membranes than for those of mammals. The results show selectivity of ocellatin-PTs to the membranes of microorganisms and the applicability of biophysical methods to clarify the interaction of AMPs with cell membranes.