323 research outputs found

    4. Circulatory Regulator.

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    Hygroscopic properties of levoglucosan and related organic compounds characteristic to biomass burning aerosol particles

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    Biomass burning, which is characterized by pyrolysis as well as vaporization and condensation of biomass constituents, is a significant source of atmospheric organic aerosols. In this study, hygroscopic properties of five organic compounds (levoglucosan, D-glucose, and vanillic, syringic, and 4-hydroxybenozoic acids), which are major pyrolysis products of wood, were measured using a tandem differential mobility analyzer. Levoglucosan, which is typically the most abundant species in wood burning aerosols, showed a significant hygroscopic growth for particles with a diameter of 100 nm. No efflorescence was observed under the measured relative humidity, and a supersaturated condition of levoglucosan-water particles was observed. The growth factors of levoglucosan are 1.08, 1.18, 1.23, and 1.38 at relative humidity (RH) of 60, 80, 85, and 90%, respectively. The measured hygroscopic curves are in general consistent with those estimated from ideal solution theory and Uniquac Functional-Group Activity Coefficient (UNIFAC) and Conductor-Like Screening Model for Real Solvent (COSMO-RS) methods. Significant hygroscopic growth was also observed for D-glucose, whose growth factor is quite similar to that of levoglucosan. However, three model pyrolysis products of lignin (i.e., vanillic-, syringic-, and 4-hydroxybenzoic acids) did not show any hygroscopic growth under the RH conditions up to 95%. On the basis of the organic composition of wood burning aerosols, the water absorption attributed to levoglucosan in wood burning aerosols is calculated to be up to 30% of the organic mass at 90% RH. This study demonstrates that oxygenated organics emitted from biomass burning could significantly enhance the hygroscopic properties of atmospheric aerosols

    Pathophysiological significance and clinical application of ANP and BNP in patients with heart failure

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    Plasma levels of ANP and BNP increase in accordance with the severity of the heart failure. In severe cases, the amount of BNP secreted surpasses that of ANP. The main secretion site of BNP is the ventricles, and that of ANP is the atria. However, ANP is also secreted from the ventricles as heart failure advances, and thus the ventricles are important sites for both BNP and ANP. It is well known that myocardial stretch is a key factor in the stimulation of the secretion of ANP and BNP, although neurohumoral factors also play a role in the secretion mechanism. The major physiological effects of ANP and BNP are vasodilation, natriuresis, and inhibition of the renin-angiotensin-aldosterone (RAA) and the sympathetic nervous systems; all of which are supposed to suppress the progression of heart failure. The inhibitory action of ANP and BNP on the RAA system has been considered to be an extra-cardiac effect. We recently reported the activation of an angiotensin-converting enzyme and aldosterone production in failing human hearts. ANP and BNP, however, would inhibit aldosterone production, not only in the adrenal cortex but also in cardiac tissue. ANP, and especially BNP, are useful markers of the heart's status during treatment for heart failure. The infusion of synthetic ANP (hANP) or BNP (Nesiritide®) is effective in the treatment of acute heart failure. In Japan, BNP occupies an important position in the diagnosis of chronic heart failure, as ANP does in the treatment of acute heart failure.Key words: natriuretic peptide, heart failure, myocardial infarction, cardiomyopathy, aldosterone. </jats:p
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