I Diretriz sobre o consumo de Gorduras e Saúde Cardiovascular Definição do grau dos níveis de evidência Recomendações Classe I: Condições para as quais há evidências conclusivas e, na sua falta, consenso geral de que o procedimento é seguro útil/eficaz. Classe II: Condições para as quais há evidências conflitantes e/ou divergência de opinião sobre segurança e utilidade/ eficácia do procedimento. Classe IIa: Peso ou evidência/opinião a favor do procedimento. A maioria aprova. Classe IIb: Segurança e utilidade/eficácia menos bem estabelecidas, não havendo predomínio de opniões a favor. Classe III: Condições para as quais há evidências e/ou consenso de que o procedimento não é útil/eficaz e, em alguns casos, pode ser prejudicial. Evidências Nível A: Dados obtidos a partir de múltiplos estudos randomizados de bom porte, concordantes e/ou de Metanálise robusta de estudos clínicos randomizados. Nível B: Dados obtidos a partir de Metanálise menos robusta, a partir de um único estudo randomizado ou de estudos não randomizados (observacionais). Nível C: Dados obtidos de opiniões consensuais de especialistas.

Membrane vesicles isolated from Escherichia coli grown under various conditions generate a transmembrane pH gradient (delta pH) of about 2 pH units (interior alkaline) under appropriate conditions when assayed by flow dialysis. Using the distribution of weak acids to measure delta pH and the distribution of the lipophilic cation triphenylmethylphosphonium to measure the electrical potential (delta psi) across the membrane, the vesicles are demonstrated to develop an electrochemical proton gradient (delta-muH+) of almost - 200 mV (interior negative and alkaline) at pH 5.5 in the presence of reduced phenazine methosulfate or D-lactate, the major component of which is a deltapH of about - 120 mV. As external pH is increased, deltapH decreases, reaching 0 at about pH 7.5 and above, while delta psi remains at about - 75 mV and internal pH remains at pH 7.5-7.8. The variations in deltapH correlate with changes in the oxidation of reduced phenazine methosulfate or D-lactate, both of which vary with external pH in a manner similar to that described for deltapH. Finally, deltapH and delta psi can be varied reciprocally in the presence of valinomycin and nigericin with little change in delta-muH+ and no change in respiratory activity. These data and those presented in the following paper (Ramos and Kaback 1976) provide strong support for the role of chemiosmotic phenomena in active transport and extend certain aspects of the chemiosmotic hypothesis.

Membrane vesicles isolated from E. coli generate a trans-membrane proton gradient of 2 pH units under appropriate conditions when assayed by flow dialysis. Using the distribution of weak acids to measure the proton gradient (ApH) and the distribution of the lipophilic cation triphenylmethylphosphonium to measure the electrical potential across the membrane (AI), the vesicles are shown to generate an electrochemical proton gradient (AiH+) of approximately -180 mV at pH 5.5 in the presence of ascorbate and phenazine methosulfate, the major component of which is a ApH of about -110 mV. As external pH is increased, ApH decreases, reaching o at pH 7.5 and above, while AI remains at about -75 mV and internal pH remains at pH 7.5. Moreover, the ability of various electron donors to drive transport is correlated with their ability to generate A4H+. In addition, ApH and Ad can be varied reciprocally in the presence of valinomycin and nigericin. These data and others (manuscript in preparation) provide convincing support for the role of chemiosmotic phenomena in active transport. Despite apparently contradictory initial observations (1-3), an increasing accumulation of experimental evidence (4-6) indicates that chemiosmotic phenomena, as postulated by Mitchell (7-10), play a central role in respiration-linked active transport in Escherichia coli membrane vesicles. It now seems clearly established that membrane vesicles prepared by the techniques developed in this laboratory retain the same orientation as the membrane in the intact cell (see ref. 11 for a summary of the evidence), and that oxidation of electron donors which drive transport in the vesicles results in the generation of a transmembrane electrical potential (interior negative) by means of electrogenic proton extrusion (6,(12)(13)(14). The potential is postulated to drive solute accumulation via facilitated diffusion of positively charged substrates such as lysine or via coupled movements of protons with neutral substrates such as lactose or proline (i.e., "symport").According to the chemiosmotic hypothesis, the total driving force generated by proton extrusion is the electrochemical potential of protons across the membrane (A,4H+) (7)(8)(9)(10) Moreover it has been shown that the potential causes the appearance of high affinity binding sites for dansyl-and azidophenylgalactosides on the outer surface of the membrane (4, 15) and that the potential is partially dissipated as a result of lactose accumulation (6). Although these findings provide evidence for the chemiosmotic hypothesis, it has also been demonstrated (6, 16) that vesicles are able to accumulate lactose and other substrates to intravesicular concentrations which are 100-fold or greater than those of the external medium.

Melatonin is now known to be a multifaceted free radical scavenger and antioxidant. It detoxifies a variety of free radicals and reactive oxygen intermediates including the hydroxyl radical, peroxynitrite anion, singlet oxygen and nitric oxide. Additionally, it reportedly stimulates several antioxidative enzymes including glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and superoxide dismutase; conversely, it inhibits a prooxidative enzyme, nitric oxide synthase. Melatonin also crosses all morphophysiological barriers, e.g., the blood-brain barrier, placenta, and distributes throughout the cell; these features increase the efficacy of melatonin as an antioxidant. Melatonin has been shown to markedly protect both membrane lipids and nuclear DNA from oxidative damage. In every experimental model in which melatonin has been tested, it has been found to resist macromolecular damage and the associated dysfunction associated with free radicals.

Conclusion: FISH is an ideal technique for analysis of chromosomal aberrations in paraffin-embedded, archival tissue specimens. While chromosome 20Q amplification has been suggested as a possible mediator of tumorigenesis in head and neck cancers, using FISH, we have shown no direct evidence of either amplification or deletion of the specific region 20q13 in head and neck squamous carcinoma.