Anticoagulant action of low, physiologic, and high albumin levels in whole blood

<div><p>Albumin is the most abundant plasma protein. Critical illness is often associated with altered, predominately decreased, serum albumin levels. This hypoalbuminaemia is usually corrected by administration of exogenous albumin. This study aimed to track the concentration-dependent influence of albumin on blood coagulation in vitro. Whole blood (WB) samples from 25 volunteers were prepared to contain low (19.3 ± 7.7 g/L), physiological (45.2 ± 7.8 g/L), and high (67.5 ± 18.1 g/L) levels of albumin. Haemostatic profiling was performed using a platelet function analyzer (PFA) 200, impedance aggregometry, a Cone and Platelet analyzer (CPA), calibrated automated thrombogram, and thrombelastometry (TEM). Platelet aggregation-associated ATP release was assessed via HPLC analysis. In the low albumin group, when compared to the physiological albumin group, we found: i) shortened PFA 200-derived closure times indicating increased primary haemostasis; ii) increased impedance aggregometry-derived amplitudes, slopes, ATP release, as well as CPA-derived average size indicating improved platelet aggregation; iii) increased TEM-derived maximum clot firmness and alpha angles indicating enhanced clot formation. TEM measurements indicated impaired clot formation in the high albumin group compared with the physiological albumin group. Thus, albumin exerted significant anticoagulant action. Therefore, low albumin levels, often present in cancer or critically ill patients, might contribute to the frequently occurring venous thromboembolism.</p></div

Ethyl pyruvate inhibits oxidation of LDL in vitro and attenuates oxLDL toxicity in EA.hy926 cells

<div><p>Background</p><p>Ethyl pyruvate (EP) exerts anti-inflammatory and anti-oxidative properties. The aim of our study was to investigate whether EP is capable of inhibiting the oxidation of LDL, a crucial step in atherogenesis. Additionally, we examined whether EP attenuates the cytotoxic effects of highly oxidized LDL in the human vascular endothelial cell line EA.hy926.</p><p>Methods</p><p>Native LDL (nLDL) was oxidized using Cu²⁺ ions in the presence of increasing amounts of EP. The degree of LDL oxidation was quantified by measuring lipid hydroperoxide (LPO) and malondialdehyde (MDA) concentrations, relative electrophoretic mobilities (REMs), and oxidation-specific immune epitopes. The cytotoxicity of these oxLDLs on EA.hy926 cells was assessed by measuring cell viability and superoxide levels. Furthermore, the cytotoxicity of highly oxidized LDL on EA.hy926 cells under increasing concentrations of EP in the media was assessed including measurements of high energy phosphates (ATP).</p><p>Results</p><p>Oxidation of nLDL using Cu²⁺ ions was remarkably inhibited by EP in a concentration-dependent manner, reflected by decreased levels of LPO, MDA, REM, oxidation-specific epitopes, and diminished cytotoxicity of the obtained oxLDLs in EA.hy926 cells. Furthermore, the cytotoxicity of highly oxidized LDL on EA.hy926 cells was remarkably attenuated by EP added to the media in a concentration-dependent manner reflected by a decrease in superoxide and an increase in viability and ATP levels.</p><p>Conclusions</p><p>EP has the potential for an anti-atherosclerotic drug by attenuating both, the oxidation of LDL and the cytotoxic effect of (already formed) oxLDL in EA.hy926 cells. Chronic administration of EP might be beneficial to impede the development of atherosclerotic lesions.</p></div

Effects of low, physiologic, and high albumin concentrations on thrombin generation assessed by means of CAT and by F1+2 plasma levels.

<p>Effects of low, physiologic, and high albumin concentrations on thrombin generation assessed by means of CAT and by F1+2 plasma levels.</p

Effects of low, physiologic, and high albumin concentrations on platelet adhesion/aggregation assessed by means of CPA.

<p>Effects of low, physiologic, and high albumin concentrations on platelet adhesion/aggregation assessed by means of CPA.</p

Effect of HUT/LBNP on coagulation values.

<p>The effect of HUT/LBNP on thrombin Peak (<i>panel A</i>) and on ETP (<i>panel B</i>), both evaluated by means of CAT, and on plasma levels of prothrombin (<i>panel C</i>) and TFPI (<i>panel D</i>), as well as on TF (<i>panel E</i>) and on t-PA (<i>panel F</i>) are shown. Each graph represents a representative experiment.</p

Effects of low, physiologic, and high albumin concentrations on platelet aggregation.

<p>Effects of low, physiologic, and high albumin concentrations on platelet aggregation.</p

ATP levels and EC in EA.hy926 cells treated with highly or mildly oxidized LDL.

<p>EP concentration-dependently attenuated the cytotoxic effect of Cu²⁺-oxidized LDL demonstrated by the increase of ATP <b>(A)</b> and EC <b>(B)</b> in EA.hy926 cells. Data represent mean ± SD (n = 6); ** p < 0.05, *** p < 0.001.</p

Effects of low, physiologic, and high albumin concentrations on primary haemostasis.

<p>Effects of low, physiologic, and high albumin concentrations on primary haemostasis.</p

ATP levels and EC in EA.hy926 cells treated with highly oxidized LDL in the presence of increasing medium concentrations of EP.

<p>EP concentration-dependently attenuated the cytotoxic effects of highly Cu²⁺-oxidized LDL demonstrated by the increase of ATP levels <b>(A)</b> and EC <b>(B)</b> in EA.hy926 cells. Data represent mean ± SD (n = 6), ** p < 0.05, *** p < 0.001.</p

Test design and study protocol.

<p>Control blood was taken after 30 min supine rest (sample 1). The orthostatic stimulation phase started with passive 70° head-up for 4 min, then 15 mm Hg LBNP was commenced in this position and increased by 15 mm Hg every 4 min. After application of −45 mm Hg suction or after development of dizziness, LBNP was stopped and the table tilted back. Supine position was maintained for 20 min, at the end of which the last blood sample was taken (sampling point 11).</p