Clin Lab
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Natriuretic peptides, atrial natriuretic peptide and brain natriuretic peptide, are key regulators in the homeostasis of salt and water excretion and in the maintenance of blood pressure. During heart failure, these peptides are highly activated because of volume overload and increased myocardial wall tension. Among all natriuretic peptides and neurohormones, brain natriuretic peptide and its N-terminal prohormone fragment have been shown to be the best markers to identify patients with heart failure. ⋯ Sensitive and specific assays without the need for plasma extraction are commercially available. The available data indicate that natriuretic peptides are powerful diagnostic and prognostic markers in heart failure patients. First data on treatment guidance are promising.
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Protease inhibitors are known by their inhibition of a viral protease that leads to production of immature and non-infectious virus particles. The novel protease inhibitor KALETRA is a co-formulation of lopinavir and ritonavir. Ritonavir reduces the metabolization of lopinavir by the cytochrome P450 3A4 isoenzyme which leads to markedly increased plasma levels of lopinavir(4). ⋯ An aliquot of 500 microl plasma, spiked with internal standard, was extracted with 500 microl 0.1 M ammonium hydroxide solution and 5 ml tert. -butyl ether. After drying under a nitrogen stream, the residue was redissolved in an eluent consisting of 50 mM phosphate buffer, pH 5.40 and acetonitrile (50:50, v/v). Chromatographic separation was accomplished on a C-18 column using a non-linear gradient elution and ultraviolet detection at 215 nm.