TY - JOUR A1 - Koessler, Juergen A1 - Hermann, Stephanie A1 - Weber, Katja A1 - Koessler, Angela A1 - Kuhn, Sabine A1 - Boeck, Markus A1 - Kobsar, Anna T1 - Role of Purinergic Receptor Expression and Function for Reduced Responsiveness to Adenosine Diphosphate in Washed Human Platelets JF - PLoS One N2 - Background Washing of platelets is an important procedure commonly used for experimental studies, e.g. in cardiovascular research. As a known phenomenon, responsiveness to adenosine diphosphate (ADP) is reduced in washed platelets, although underlying molecular mechanisms—potentially interfering with experimental results—have not been thoroughly studied. Objectives Since ADP mediates its effects via three purinergic receptors P2Y1, P2X1 and P2Y12, their surface expression and function were investigated in washed platelets and, for comparison, in platelet-rich-plasma (PRP) at different time points for up to 2 hours after preparation. Results In contrast to PRP, flow cytometric analysis of surface expression in washed platelets revealed an increase of all receptors during the first 60 minutes after preparation followed by a significant reduction, which points to an initial preactivation of platelets and consecutive degeneration. The activity of the P2X1 receptor (measured by selectively induced calcium flux) was substantially maintained in both PRP and washed platelets. P2Y12 function (determined by flow cytometry as platelet reactivity index) was partially reduced after platelet washing compared to PRP, but remained stable in course of ongoing storage. However, the function of the P2Y1 receptor (measured by selectively induced calcium flux) continuously declined after preparation of washed platelets. Conclusion In conclusion, decreasing ADP responsiveness in washed platelets is particularly caused by impaired activity of the P2Y1 receptor associated with disturbed calcium regulation, which has to be considered in the design of experimental studies addressing ADP mediated platelet function. KW - platelets KW - flow cytometry KW - adenosine KW - statistical data KW - platelet activation KW - platelet aggregation KW - phosphorylation KW - blood plasma Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-146400 VL - 11 IS - 1 ER - TY - JOUR A1 - Haring, Bernhard A1 - Wyler von Ballmoos, Moritz C. A1 - Appel, Lawrence J. A1 - Sacks, Frank M. T1 - Healthy Dietary Interventions and Lipoprotein (a) Plasma Levels: Results from the Omni Heart Trial N2 - Background: Increased lipoprotein(a) [Lp(a)] levels are associated with atherosclerotic cardiovascular disease. Studies of dietary interventions on changes in Lp(a) are sparse. We aimed to compare the effects of three healthy dietary interventions differing in macronutrient content on Lp(a) concentration. Methods: Secondary analysis of a randomized, 3-period crossover feeding study including 155 (89 blacks; 66 whites) individuals. Participants were given DASHtype healthy diets rich in carbohydrates [Carb], in protein [Prot] or in unsaturated fat [Unsat Fat] for 6 weeks each. Plasma Lp(a) concentration was assessed at baseline and after each diet. Results: Compared to baseline, all interventional diets increased mean Lp(a) by 2 to 5 mg/dl. Unsat Fat increased Lp(a) less than Prot with a difference of 1.0 mg/dl (95% CI, -0.5, 2.5; p=0.196) in whites and 3.7 mg/dl (95% CI, 2.4, 5.0; p<0.001) in blacks (p-value between races=0.008); Unsat Fat increased Lp(a) less than Carb with a difference of 20.6 mg/dl, 95% CI, -2.1, 0.9; p=0.441) in whites and 21.5 mg/dl (95% CI, -0.2, -2.8; p=0.021) in blacks (p-value between races=0.354). Prot increased Lp(a) more than Carb with a difference of 0.4 mg/dl (95% CI, -1.1, 1.9; p=0.597) in whites and 2.2 mg/dl (95%CI, 0.9, 3.5; p=0.001) in blacks (p-value between races=0.082). Conclusion: Diets high in unsaturated fat increased Lp(a) levels less than diets rich in carbohydrate or protein with greater changes in blacks than whites. Our results suggest that substitutions with dietary mono- and polyunsaturated fatty acids in healthy diets may be preferable over protein or carbohydrates with regards to Lp(a). KW - diet KW - carbohydrates KW - blood plasma KW - heart KW - food consumption KW - cholesterol KW - fatty acids KW - plasma proteins Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-111005 ER - TY - JOUR A1 - Högger, Petra A1 - Kurlbaum, Max A1 - Mülek, Melanie T1 - Facilitated Uptake of a Bioactive Metabolite of Maritime Pine Bark Extract (Pycnogenol) into Human Erythrocytes JF - PLoS ONE N2 - Many plant secondary metabolites exhibit some degree of biological activity in humans. It is a common observation that individual plant-derived compounds in vivo are present in the nanomolar concentration range at which they usually fail to display measurable activity in vitro. While it is debatable that compounds detected in plasma are not the key effectors of bioactivity, an alternative hypothesis may take into consideration that measurable concentrations also reside in compartments other than plasma. We analysed the binding of constituents and the metabolite δ-(3,4-dihydroxy-phenyl)-γ-valerolactone (M1), that had been previously detected in plasma samples of human consumers of pine bark extract Pycnogenol, to human erythrocytes. We found that caffeic acid, taxifolin, and ferulic acid passively bind to red blood cells, but only the bioactive metabolite M1 revealed pronounced accumulation. The partitioning of M1 into erythrocytes was significantly diminished at higher concentrations of M1 and in the presence of glucose, suggesting a facilitated transport of M1 via GLUT-1 transporter. This concept was further supported by structural similarities between the natural substrate α-D-glucose and the S-isomer of M1. After cellular uptake, M1 underwent further metabolism by conjugation with glutathione. We present strong indication for a transporter-mediated accumulation of a flavonoid metabolite in human erythrocytes and subsequent formation of a novel glutathione adduct. The physiologic role of the adduct remains to be elucidated. KW - blood plasma KW - cell metabolism KW - drug metabolism KW - glucose KW - glucos metabolism KW - glutathione KW - plasma proteins KW - red blood cells Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96656 ER - TY - JOUR A1 - Schupp, Nicole A1 - Ali, Badreldin H. A1 - Beegam, Sumyia A1 - Al-Husseni, Isehaq A1 - Al-Shukaili, Ahmed A1 - Nemmar, Abderrahim A1 - Schierling, Simone A1 - Queisser, Nina T1 - Effect of gum arabic on oxidative stress and inflammation in adenine-induced chronic renal failure in rats JF - PLoS One N2 - Inflammation and oxidative stress are known to be involved in the pathogenesis of chronic kidney disease in humans, and in chronic renal failure (CRF) in rats. The aim of this work was to study the role of inflammation and oxidative stress in adenine-induced CRF and the effect thereon of the purported nephroprotective agent gum arabic (GA). Rats were divided into four groups and treated for 4 weeks as follows: control, adenine in feed (0.75%, w/w), GA in drinking water (15%, w/v) and adenine+GA, as before. Urine, blood and kidneys were collected from the rats at the end of the treatment for analysis of conventional renal function tests (plasma creatinine and urea concentration). In addition, the concentrations of the pro-inflammatory cytokine TNF-a and the oxidative stress markers glutathione and superoxide dismutase, renal apoptosis, superoxide formation and DNA double strand break frequency, detected by immunohistochemistry for c-H2AX, were measured. Adenine significantly increased the concentrations of urea and creatinine in plasma, significantly decreased the creatinine clearance and induced significant increases in the concentration of the measured inflammatory mediators. Further, it caused oxidative stress and DNA damage. Treatment with GA significantly ameliorated these actions. The mechanism of the reported salutary effect of GA in adenine-induced CRF is associated with mitigation of the adenine-induced inflammation and generation of free radicals. KW - adenine KW - blood plasma KW - creatinine KW - inflammation KW - inflammatory diseases KW - Kidneys KW - Oxidative stress KW - Water resources Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-95787 ER -