Acumulação de metais pesados pelo uso de insumos agrícolas na microbacia de Caetés, Paty do Alferes, RJ.

O município de Paty do Alferes, localizado na região serrana do Estado do Rio de Janeiro, inserido no bioma Mata Atlântica e com declividade de até 50%, tem exclusivamente a horticultura, com uso intensivo de insumos, como atividade econômica (40% de todo o tomate do estado e um grande percentual de outras hortaliças - repolho, pepino, vagem, pimentão), mas, em função do declínio rápido da produtividade, as áreas estão sendo abandonadas, dando lugar a pastagem com pouco manejo. Diante do diagnóstico do uso excessivo de agroquímicos, este trabalho teve o objetivo de avaliar o seu impacto na contaminação do solo, água, sedimentos e plantas hortícolas por metais pesados na microbacia de Caetés (Paty do Alferes, RJ) e a influência da topografia e do uso agrícola na acumulação de metais pesados. Para tanto selecionaram-se duas toposseqüências de solos representativas da microbacia de Caetés: (a) toposseqüência 1 (T1) apresenta menor declividade e pendente longa, com três formas distintas de uso: capoeira, pasto (antiga área de horticultura) e horticultura atual; (b) na outra (T2), observa-se declividade mais acentuada (45%) e pendente curta, sendo os tipos de uso do solo os mesmos de T1. Notou-se que a contaminação por metais pesados nos solos da microbacia de Caetés concentrou-se onde ocorria a aplicação intensiva de agroquímicos (áreas de horticultura), mas não atingiu os níveis críticos estabelecidos para solos e estava distribuída em formas químicas pouco biodisponíveis (tomate, pimentão, repolho e pepino). A acumulação de metais pesados só não foi maior devido ao terreno ser muito declivoso, o que promoveu um arraste excessivo e contínuo da camada arável, sendo depositado nos córregos pelo uso agrícola inadequado à topografia. Em virtude do processo erosivo, constataram-se nos sedimentos da microbacia de Caetés incrementos nos teores totais de metais pesados de acordo com a posição de coleta na área, todavia esses metais não estavam presentes em formas químicas biodisponíveis. Entretanto, houve contaminação da água do córrego e do açude, que apresentou teor total de Mn e Cd acima dos padrões máximos estabelecidos para água potável.bitstream/item/159432/1/bp05-1998.pdfConvênio Financiadora de Estudos e Projetos (FINEP), Comunidade Econômica Européia (CEE) e Fundo Nacional de Meio Ambiente (FNMA)

Unsaturated Fatty Acids Revert Diet-Induced Hypothalamic Inflammation in Obesity

Background: In experimental models, hypothalamic inflammation is an early and determining factor in the installation and progression of obesity. Pharmacological and gene-based approaches have proven efficient in restraining inflammation and correcting the obese phenotypes. However, the role of nutrients in the modulation of hypothalamic inflammation is unknown. Methodology/Principal Findings: Here we show that, in a mouse model of diet-induced obesity, partial substitution of the fatty acid component of the diet by flax seed oil (rich in C18:3) or olive oil (rich in C18:1) corrects hypothalamic inflammation, hypothalamic and whole body insulin resistance, and body adiposity. In addition, upon icv injection in obese rats, both v3 and v9 pure fatty acids reduce spontaneous food intake and body mass gain. These effects are accompanied by the reversal of functional and molecular hypothalamic resistance to leptin/insulin and increased POMC and CART expressions. In addition, both, v3 and v9 fatty acids inhibit the AMPK/ACC pathway and increase CPT1 and SCD1 expression in the hypothalamus. Finally, acute hypothalamic injection of v3 and v9 fatty acids activate signal transduction through the recently identified GPR120 unsaturated fatty acid receptor. Conclusions/Significance: Unsaturated fatty acids can act either as nutrients or directly in the hypothalamus, reverting dietinduced inflammation and reducing body adiposity. These data show that, in addition to pharmacological and geneti

Design and development of a peptide-based adiponectin receptor agonist for cancer treatment

<p>Abstract</p> <p>Background</p> <p>Adiponectin, a fat tissue-derived adipokine, exhibits beneficial effects against insulin resistance, cardiovascular disease, inflammatory conditions, and cancer. Circulating adiponectin levels are decreased in obese individuals, and this feature correlates with increased risk of developing several metabolic, immunological and neoplastic diseases. Thus, pharmacological replacement of adiponectin might prove clinically beneficial, especially for the obese patient population. At present, adiponectin-based therapeutics are not available, partly due to yet unclear structure/function relationships of the cytokine and difficulties in converting the full size adiponectin protein into a viable drug.</p> <p>Results</p> <p>We aimed to generate adiponectin-based short peptide that can mimic adiponectin action and be suitable for preclinical and clinical development as a cancer therapeutic. Using a panel of 66 overlapping 10 amino acid-long peptides covering the entire adiponectin globular domain (residues 105-254), we identified the 149-166 region as the adiponectin active site. Three-dimensional modeling of the active site and functional screening of additional 330 peptide analogs covering this region resulted in the development of a lead peptidomimetic, ADP 355 (H-DAsn-Ile-Pro-Nva-Leu-Tyr-DSer-Phe-Ala-DSer-NH₂). In several adiponectin receptor-positive cancer cell lines, ADP 355 restricted proliferation in a dose-dependent manner at 100 nM-10 μM concentrations (exceeding the effects of 50 ng/mL globular adiponectin). Furthermore, ADP 355 modulated several key signaling pathways (AMPK, Akt, STAT3, ERK1/2) in an adiponectin-like manner. siRNA knockdown experiments suggested that ADP 355 effects can be transmitted through both adiponectin receptors, with a greater contribution of AdipoR1. <it>In vivo</it>, intraperitoneal administration of 1 mg/kg/day ADP 355 for 28 days suppressed the growth of orthotopic human breast cancer xenografts by ~31%. The peptide displayed excellent stability (at least 30 min) in mouse blood or serum and did not induce gross toxic effects at 5-50 mg/kg bolus doses in normal CBA/J mice.</p> <p>Conclusions</p> <p>ADP 355 is a first-in-class adiponectin receptor agonist. Its biological activity, superior stability in biological fluids as well as acceptable toxicity profile indicate that the peptidomimetic represents a true lead compound for pharmaceutical development to replace low adiponectin levels in cancer and other malignancies.</p

The Secret Life of the Anthrax Agent Bacillus anthracis: Bacteriophage-Mediated Ecological Adaptations

Ecological and genetic factors that govern the occurrence and persistence of anthrax reservoirs in the environment are obscure. A central tenet, based on limited and often conflicting studies, has long held that growing or vegetative forms of Bacillus anthracis survive poorly outside the mammalian host and must sporulate to survive in the environment. Here, we present evidence of a more dynamic lifecycle, whereby interactions with bacterial viruses, or bacteriophages, elicit phenotypic alterations in B. anthracis and the emergence of infected derivatives, or lysogens, with dramatically altered survival capabilities. Using both laboratory and environmental B. anthracis strains, we show that lysogeny can block or promote sporulation depending on the phage, induce exopolysaccharide expression and biofilm formation, and enable the long-term colonization of both an artificial soil environment and the intestinal tract of the invertebrate redworm, Eisenia fetida. All of the B. anthracis lysogens existed in a pseudolysogenic-like state in both the soil and worm gut, shedding phages that could in turn infect non-lysogenic B. anthracis recipients and confer survival phenotypes in those environments. Finally, the mechanism behind several phenotypic changes was found to require phage-encoded bacterial sigma factors and the expression of at least one host-encoded protein predicted to be involved in the colonization of invertebrate intestines. The results here demonstrate that during its environmental phase, bacteriophages provide B. anthracis with alternatives to sporulation that involve the activation of soil-survival and endosymbiotic capabilities