Kinins are vasoactive peptide hormones that can confer protection against the development of hypertension. Because their efficacy is greatly influenced by the rate of enzymatic degradation, the activities of various kininases in plasma and blood of spontaneously hypertensive rats (SHR) were compared with those in normotensive Wistar-Kyoto rats (WKY) to identify pathogenic alterations. Either plasma or whole blood was incubated with bradykinin (10 microM). Bradykinin and kinin metabolites were measured by high-performance liquid chromatography. Kininase activities were determined by cumulative inhibition of angiotensin I-converting enzyme (ACE), carboxypeptidase N (CPN), and aminopeptidase P (APP), using selective inhibitors. Plasma of WKY rats degraded bradykinin at a rate of 13.3 +/- 0.94 micromol x min(-1) x l(-1). The enzymes ACE, APP, and CPN represented 92% of this kininase activity, with relative contributions of 52, 25, and 16%, respectively. Inclusion of blood cells at physiological concentrations did not extend the activities of these plasma kininases further. No differences of kinin degradation were found between WKY and SHR. The identical conditions of kinin degradation in WKY and SHR suggest no pathogenic role of kininases in the SHR model of genetic hypertension.

No abstract

Metal–organic frameworks (MOFs) have great potential as an efficient alternative to current separation and purification procedures of a large variety of solvent mixtures—a critical process in many applications. Due to the huge number of existing MOFs, it is of key importance to identify high-throughput analytical tools, which can be used for their screening and performance ranking. In this context, the present work introduces a simple, fast, and inexpensive approach by compact low-field proton nuclear magnetic resonance (NMR) relaxometry to investigate the efficiency of MOF materials for the separation of a binary solvent mixture. The mass proportions of two solvents within a particular solvent mixture can be quantified before and after separation with the help of a priori established correlation curves relating the effective transverse relaxation times T2eff and the mass proportions of the two solvents. The new method is applied to test the separation efficiency of powdered UiO-66(Zr) for various solvent mixtures, including linear and cyclic alkanes and benzene derivate, under static conditions at room temperature. Its reliability is demonstrated by comparison with results from 1H liquid-state NMR spectroscopy.

No abstract