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Thrombosis and Haemostasis 08/2010; 104(2):412-4. · 5.04 Impact Factor
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Journal of the American College of Cardiology 04/2010; 55(14):1502-3. · 14.16 Impact Factor
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ABSTRACT: Circulating adult CD34(+)VEGFR2(+) endothelial progenitor cells (EPCs) have been shown to differentiate into endothelial cells, thus contributing to vascular homeostasis. Furthermore, a subset of circulating CD14(+) monocytes coexpresses CD16 together with the angiopoietin receptor Tie2 and has been functionally implicated in tumor angiogenesis. However, clinically applicable protocols for flow cytometric quantification of EPCs and Tie2(+) monocytes in peripheral blood and a consensus on reference values remain elusive. The number of Tie2(+)CD14(+)CD16(mid) angiogenic monocytes and CD34(+)VEGFR2(+)CD45(low/-) EPCs was assessed in the peripheral venous blood of patients with stable coronary artery disease by three-color flow cytometry using specific monoclonal antibodies conjugated to PerCP, PE, PE-Cy7, APC, and APC-Cy7. Scatter multigating with exclusion of dead cells was performed to dissect complex mononuclear cell populations. This analysis was further refined by matching bright fluorochromes (PE-Cy7, PE, APC) with dimly expressed markers (CD34, VEGFR2, Tie2), by automatic compensation for minimizing fluorescence spillover and by using fluorescence-minus-one (FMO) controls to determine positive/negative boundaries. Presuming a Gaussian distribution, we obtained average values (mean +/- SD) of 1.45 +/- 1.29% for Tie2(+)CD14(+)CD16(mid) monocytes (n = 11, range: 0.12-3.64%) and 0.019 +/- 0.013% for CD34(+)VEGFR2(+)CD45(low/-) EPCs (n = 17, range: 0.003-0.042%). The intra- and inter-assay variability was 1.6% and 4.5%, respectively. We have optimized a fast and sensitive assay for the flow cytometric quantification of circulating angiogenic monocytes and EPCs in cardiovascular medicine. This protocol may represent a basis for standardized analysis and monitoring of these cell subsets to define their normal range and prognostic/diagnostic value in clinical use.
Cytometry Part A 10/2009; 75(10):848-53. · 3.73 Impact Factor
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Thomas Lauer,
Christian Heiss,
Jan Balzer,
Eva Kehmeier,
Sarah Mangold, Thorsten Leyendecker,
Jessica Rottler,
Christian Meyer,
Marc W Merx,
Malte Kelm,
Tienush Rassaf
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ABSTRACT: Age-dependent alterations of the vessel wall may predispose older individuals to increased cardiovascular pathology. Aging is associated with an impaired bioactivity of nitric oxide (NO). Plasma nitrite reflects NO-synthase activity under fasting conditions and is an important storage pool of NO. To test the hypothesis that aging is associated with an impaired capacity of the vasculature to increase plasma nitrite during exercise, 29 young and 28 old healthy individuals (25 +/- 1 years and 58 +/- 2 years; P < 0.001) without major cardiovascular risk factors were enrolled. Exercise stress was similar in both groups. Baseline nitrite did not differ (107 +/- 8 vs. 82 +/- 10 nmol/l, young vs. old; n.s.) although a trend toward higher nitrite levels in young individuals was seen. In young subjects, exercise increased plasma nitrite by 38 +/- 7% (P < 0.001) compared to only 13 +/- 8% (P = n.s.) in older subjects. L-NMMA blocked increases of nitrite. Endothelial function, as defined by flow-mediated-dilation (FMD) of the brachial artery via ultrasound, was impaired in older subjects (5.4 +/- 0.4% vs. 6.7 +/- 0.3%; P < 0.01). Multivariate analysis showed that age (P = 0.007), BMI (P = 0.010), and LDL (P = 0.021) were independent predictors of nitrite increase. The fact that aging is associated with an impaired capacity of the vasculature to adequately increase nitrite to physiological stimuli may contribute to attenuated maintenance and further deterioration of vascular homeostasis with aging.
Archiv für Kreislaufforschung 05/2008; 103(3):291-7. · 7.35 Impact Factor
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ABSTRACT: Nitrite is the main oxidation product of nitric oxide (NO) in plasma. It sensitively reflects changes in endothelial NO synthase (eNOS) activity under fasting conditions and serves as an endocrine NO donor, contributing to the regulation of blood flow through reaction with haemoglobin. As NO is necessary to maintain an adequate vascular response to the increased demands of blood flow, it is believed to be important for vasodilation induced by exercise.
To investigate whether the capacity of the vasculature to produce nitrite is associated with exercise performance.
With the use of chemiluminescence detection, nitrite concentrations in 55 healthy subjects (mean (SEM) age 40 (2) years; 22 men) were studied before and after an exercise test, and endothelial function was determined by measuring flow-mediated dilation of the brachial artery using high-resolution ultrasound. In a subset of subjects, the NOS inhibitor, N(G)-monomethyl-L-arginine, was applied to elucidate the effect of eNOS on changes in nitrite.
Exercise significantly (p<0.001) increased plasma nitrite from 97 (6) to 125 (8) nM. The relative increase in plasma nitrite was related to flow-mediated dilation (6.1 (0.3)%; r = 0.36; p = 0.01). N(G)-Monomethyl-L-arginine blocked increases in nitrite. Post-exercise nitrite concentration correlated with exercise performance, as determined by maximally reached stress power (r = 0.37; p<0.007), and inversely with age. Multivariate analysis showed that both age and post-exercise nitrite concentration were independent predictors of stress endurance and power.
The results suggest a role for plasma nitrite in the adaptation of haemodynamics during exercise. An impaired increase in plasma nitrite may limit exercise capacity.
British journal of sports medicine 10/2007; 41(10):669-73; discussion 673. · 2.55 Impact Factor
