Search

Enrichment of lithium isotopes by displacement chromatography on strong acid cation exchanger was investigated. Narrow particle fraction of Dowex 50 WX 2 cation exchanger having diameter of 150-200 µm and total exchange capacity of 1.31 meq mL was used as stationary phase. As a mobile phase, 1 mol L solution of ammonium nitrate solution was used. Shape and position of Li chromatographic peak, was determined by atomic emission spectroscopy (AES). Isotope ratio was estimated by ICP-MS after 1, 8 and 10 enrichment steps. Value of separation factor for Li in one step was determined to be 1.027. [ABSTRACT FROM AUTHOR]

Pulmonary hypertension is a group of diseases characterized by elevated pulmonary artery pressure and pulmonary vascular resistance with significant morbidity and mortality. The most prevalent type is pulmonary hypertension secondary to left heart disease (PH-LHD). The available experimental models of PH-LHD use partial pulmonary clamping by technically nontrivial open-chest surgery with lengthy recovery. We present a simple model in which the reduction of the cross-sectional area of the ascending aorta is achieved not by external clamping but by partial intravascular obstruction without opening the chest. In anesthetized rats, a blind polyethylene tubing was advanced from the right carotid artery to just above the aortic valve. The procedure is quick and easy to learn. Three weeks after the procedure, left heart pressure overload was confirmed by measuring left ventricular end-diastolic pressure by puncture (1.3 ± 0.2 vs. 0.4 ± 0.3 mmHg in controls, mean ± SD, P < 0.0001). The presence of pulmonary hypertension was documented by measuring pulmonary artery pressure by catheterization (22.3 ± 2.3 vs. 16.9 ± 2.7 mmHg, P = 0.0282) and by detecting right ventricular hypertrophy and increased muscularization of peripheral pulmonary vessels. Contributions of a precapillary vascular segment and vasoconstriction to the increased pulmonary vascular resistance were demonstrated, respectively, by arterial occlusion technique and by normalization of resistance by a vasodilator, sodium nitroprusside, in isolated lungs. These changes were comparable, but not additive, to those induced by an established pulmonary hypertension model, chronic hypoxic exposure. Intravascular partial aortic obstruction offers an easy model of pulmonary hypertension induced by left heart disease that has a vasoconstrictor and precapillary component. NEW & NOTEWORTHY We present a new, simple model of a clinically important type of pulmonary hypertension, that induced by left heart failure. Left ventricular pressure overload is induced in rats by inserting a blinded cannula into the ascending aorta via carotid artery access. This partial intravascular aortic obstruction, which does not require opening of the chest and prolonged recovery, causes pulmonary hypertension, which has a precapillary and vasoconstrictor as well as a vascular remodeling component.

Amanita strobiliformis (European Pine Cone Lepidella) is an ectomycorrhizal fungus of the Amanitaceae family known to hyperaccumulate Ag in the sporocarps. Two populations (ecotypes) of A. strobiliformis collected from two urban forest plantations in Prague, Czech Republic, were investigated. The concentrations of Ag, Cu, Cd, and Zn were determined in the mushrooms. The metal mobility and fractionation in the soils was investigated by single extractions and sequential extraction. The soil distribution of A. strobiliformis mycelium was assessed by quantitative polymerase chain reaction (qPCR). The metal uptake from the soil into the mushroom sporocarps was traced by Pb isotopic fingerprinting. The findings suggested that A. strobiliformis (i) accumulates primarily Ag from the topsoil layer (circa 12cm deep) and (ii) accumulates Ag associated with the "reducible soil fraction". The concentrations of all metals, particularly Ag and Cu, were significantly higher in the A. strobiliformis sporocarps from one of the investigated sites (Klíčov). The elevated concentrations of Ag in the sporocarps from Klíčov can possibly be attributed to the higher Ag content in the topsoil layer found at this site. However, the simultaneously elevated concentrations of Cu in A. strobiliformis from Klíčov cannot be explained by the differences in the geochemical background and should be attributed to biological factors., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Tetrahydrobiopterin (BH4) is an essential cofactor for nitric oxide synthases (NOS). Oxidative stress oxidises BH4 to dihydrobioptein (BH2), resulting in the uncoupling of the two enzymatic domains of NOS and the production of superoxide rather than NO (NOS uncoupling). Oxidative stress is known to be increased in the early stage of chronic hypoxia. This study investigated the participation of NOS uncoupling in the early phase of hypoxia-induced pulmonary hypertension in rats. Rats were exposed to 10% O(2) for 4 days. We investigated the effect of BH4 in vitro on isolated rat lungs and isolated rat peripheral pulmonary blood vessels and in vivo on exhaled NO concentration in exhaled air. BH4 attenuated hypoxic pulmonary vasoconstriction in isolated lungs and its effect was reversed by l-NAME (NOS inhibitor). The main finding of the study is that the effect of BH4 was smaller in rats exposed to 4 days of hypoxia than in normoxic controls. The finding was similar in isolated pulmonary blood vessels. BH4 increased exhaled NO in both normoxic and hypoxic rats. This increase was blunted by l-NIL (specific iNOS inhibitor) and therefore attributable to iNOS. We conclude that BH4 increased NO production in both normoxic and hypoxic rats. The increase was, however, smaller in hypoxic lungs than in controls. We assume that the smaller increase in NO production in hypoxic lungs is due to the decreased BH4/BH2 ratio in chronic hypoxia and NOS uncoupling resulting from this condition., (Copyright © 2012 Elsevier B.V. All rights reserved.)