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Clinical hemorheology and microcirculation [journal]
- Immunological evaluation of polystyrene and poly(ether imide) cell culture inserts with different roughness. [Journal Article]
- Clin Hemorheol Microcirc 2014 Jan 1; 56(3):285-6.
- Effect of erythrocyte aggregation at pathological levels on NO/O2 transport in small arterioles. [JOURNAL ARTICLE]
- Clin Hemorheol Microcirc 2014 Apr 14.
This study examined the effects of red blood cell (RBC) aggregation at pathological levels on NO/O2 transport in small arterioles. Transient gas diffusion simulations were performed with in vivo cell-free layer (CFL) widths data obtained from arteriolar flows in the rat cremaster muscle. The CFL data were measured at physiological and pathological levels of aggregation under reduced flow conditions (pseudoshear rate = 31.4 ± 10.5 s-1). Our results showed that the mean peak NO concentration significantly decreased with increasing the aggregation level from non-aggregating to normal-aggregating (P < 0.05)and to hyper-aggregating (P < 0.01) conditions. In contrast, the partial O2 pressure (PO2) in pathological aggregating conditions significantly increased from those under non-aggregating (P < 0.001) and normal-aggregating (P < 0.05) conditions. Although the NO scavenging by RBCs could be impaired with a thicker CFL at higher levels of aggregation, the overall decrease in NO production due to reduction of wall shear stress with the thicker CFL dominantly limited the NO availability in tissue. On the other hand, the O2 availability in tissue increased due to the relatively high core hematocrit in the blood lumen with the thicker CFL.
- Impact of fluid resuscitation with hypertonic-hydroxyethyl starch versus lactated ringer on hemorheology and microcirculation in hemorrhagic shock. [JOURNAL ARTICLE]
- Clin Hemorheol Microcirc 2014 Apr 9.
The choice of volume expander for fluid resuscitation in hemorrhagic shock is still debated. Changes in plasma viscosity (PV) are barely investigated while PV modulates functional capillary density, microcirculation and organ function. The present study evaluated the impact of 2 strategies of fluid resuscitation in hemorrhagic shock in pigs. Ten pigs were subjected to hemorrhagic shock and randomly assigned to a low viscosity fluid regimen (Lactated Ringer's, LR) group or a high viscosity regimen (hypertonic-hydroxyethyl starch, HES) for volume resuscitation. Sublingual microcirculatory flow and tissue oxygen tension were assessed together with macro- and microcirculatory, biochemical and rheological variables at baseline, 30 minutes after hemorrhagic shock, immediately after reaching resuscitation endpoints (R-0), and 60 minutes after resuscitation (R-60). PV decreased similarly in both groups following resuscitation (from 1.36 [1.32-1.38] to 1.21 [1.21-1.23] for LR, and from 1.32 [1.31-1.32] to 1.20 [1.17-1.21] mPa.s for HES). No differences were found between the groups for other rheological variables, microcirculatory flow or tissue oxygen tension at R-0 and R-60. Despite a 6-fold difference in the volumes required to achieve blood flow endpoints, commercially available volume expanders had similar effects on rheological and microcirculatory variables, irrespective of their viscosity. Our findings are consistent with the absence of clinically relevant differences between crystalloid and colloid resuscitation of hemorrhagic shock.
- Muscle VO2 and forearm blood flow repeatability during venous and arterial occlusions in healthy and coronary heart disease subjects. [JOURNAL ARTICLE]
- Clin Hemorheol Microcirc 2014 Apr 9.
This study aims were: 1) to assess forearm blood flow (FBF) and muscle oxygen consumption (mVO2) repeatability assessed with near-infra red spectroscopy (NIRS) during venous occlusions (VO) in middle aged healthy subjects and patients with stable coronary heart disease (CHD), 2) to assess the agreement between mVO2 calculated from NIRS signals during VO and arterial occlusion (AO) in 18 middle aged healthy subjects and 12 patients with CHD. FBF and mVO2 were measured using NIRS during 2 successive VO (1-min duration), followed by a 5-min AO. Repeatability for FBF and mVO2 during VO was assessed with intra class correlation (ICC), coefficient of variation (CV %) and agreement between VO and AO mVO2 was assessed with a Bland and Altman analysis. FBF and mVO2 during VO were highly reproducible in healthy (FBF: ICC 0.73, CV% 9.75; mVO2: ICC 0.89, CV% 12.6) and CHD subjects (FBF: ICC 0.95, CV% 10.26; mVO2: ICC 0.98, CV% 7.92). VO and AO mVO2 were in agreement in healthy (mean bias: 0.002 mL O2.min-1.100g-1) and CHD subjects (mean bias: 0.014 mL O2.min-1.100g-1). FBF and mVO2 measured with NIRS during VO and/or AO are highly reproducible methods to assess microvascular function in healthy subjects and stable CHD patients.
- Plasma viscosity is increased in subjects with elevated ankle brachial index. [JOURNAL ARTICLE]
- Clin Hemorheol Microcirc 2014 Mar 24.
Peripheral artery occlusive disease (PAOD) is associated with increased cardiovascular risk (CVR). Recently it has been reported that also the increased stiffness of lower limb arteries is associated with increased CVR. In particular, subjects with poorly compressible arteries (PCA) appear to have a CVR even higher than that of subjects with PAOD. Limited data are available on the role of hemorheological factors in determining increase in arterial stiffness. Our study aimed to investigate possible association between blood and plasma viscosity and elevated ankle brachial index (ABI).Subjects were free-living participants to a cardiovascular disease screening campaign. Sixty-two subjects with ABI ranging 1.3-1.4, and 20 with ABI >1.4 were matched with 124 and 40 control subjects, respectively. Cardiovascular disease risk factors (blood pressure, blood lipids, glucose, cigarette smoking, obesity) were evaluated by routine methods. Blood and plasma viscosities were measured by a cone-plate viscometer. Ankle-brachial index was computed as measure of arterial stiffness.Compared with controls, who were carefully matched for age, sex and all cardiovascular risk factors, subjects with elevated ABI values had increased levels of plasma viscosity (1.42 ± 0.11 vs. 1.35 ± 0.10 cP, p < 0.001, for subjects with ABI ranging 1.3-1.4, and 1.41 ± 0.10 vs. 1.33 ± 0.10 cP, p < 0.01, for subjects with ABI >1.4). No difference in blood viscosity was observed.The present investigation provides evidence that plasma viscosity is increased in subjects with elevated ABI values, independently of other cardiovascular risk factors. This finding contributes to explain the high CVR of patients with PCA.
- Erythrocyte deformability and nitric oxide mobilization under pannexin-1 and PKC dependence. [JOURNAL ARTICLE]
- Clin Hemorheol Microcirc 2014 Mar 4.
The erythrocyte adenosine triphosphate (ATP) is utilised for protein phosphorylation and exported through the pannexin 1 hemichannel (Px1) in the microcirculation. The physiological stimuli for ATP release are dependent of blood shear rate level and of the tissue oxygen content. The deoxygenated and oxygenated states of haemoglobin are respectively bound and unbound to N terminal domain of the protein band 3 of the erythrocyte membrane in dependence of its degree of phosphorylation. The protein tyrosine kinase (PTK) and protein tyrosine phosphatase (PTP) contribute to the phosphorylation degree of band 3 and are modulated by protein kinase C (PKC). Chelerythrine (Che) is a competitive inhibitor of ATP for PKC and a negative modulator of erythrocyte deformability. The aim of this study was to assess the mobilization of nitric oxide (NO) in erythrocyte in absence and presence of Che and Px1 inhibitor (carbenoxolone). Erythrocyte deformability was evaluated in presence of carbenoxolone (Carb). Regarding the effects observed in the erythrocyte by presence of Che or Carb, the values of efflux of NO and the concentration of nitrosogluthatione are similar and with no changes in relation to their absence. Px1inhibition by Carb 10 μM ameliorates the erythrocyte deformability at a shear force of 0.6 and 1.2 Pa. The PKC inhibitor shows similar effects to the Carb on the mobilization of nitric oxide in erythrocyte. The blockage of ATP release by Carb from erythrocytes suggests a possible benefit to develop in ischemia reperfusion or in inflammatory response where will be needed to rescue the excess of NO present and ameliorate the red blood cell deformability at low shear rates.
- Comparison of contrast-enhanced ultrasound and compression elastography in the follow-up after endovascular aortic aneurysm repair. [JOURNAL ARTICLE]
- Clin Hemorheol Microcirc 2014 Mar 4.
To compare compression elastography and contrast enhanced ultrasound in the follow-up after endovascular aortic aneurysm repair.In this retrospective study a cohort of 33 patients with both CEUS and elastography follow-up examinations after EVAR were included. The examinations were done with a Siemens S 2000 with curved array 4 MHz multi-frequency transducer.Regarding our inclusion and exclusion criteria we obtained 33 patients. CEUS was used as the preferred examination in determining the presence of an endoleak. The true positive rate for the detection of Endoleaks with compression elastography was 42.4% (14/33), the false positive rate was 12.1% (4/33), the true negative rate was 15.2% (5/33) and the false negative rate was 30.3% (10/33). The sensitivity of compression elastography was therefore 58.3% and the specifity was 55.6%. Kappa coefficient was 0.115.Compression elastography does not seem to have any additional advantages in the detection and classification of endoleaks in comparison to CEUS.
- The last bite was deadly - About responsibility in scientific publishing. [JOURNAL ARTICLE]
- Clin Hemorheol Microcirc 2014 Mar 4.
Some open access journals are believed to have devaluated the highly respected image of the scientific journal. This has been, it is claimed, verified. Yet the project we believe failed and we show why we think that it failed. The study itself was badly conducted and the report, which Science published, was itself a perfect example of "bad science". If the article that was published in Science were to be taken as one of the "test" articles and Science as a victim journal (a perfect control though), the study would show the opposite of what author concluded in his paper: 100% of the controls (normal non-open access journals, in the present study this was Science) the "bait" paper for publication, while in the experimental group only about 60% (open access journals) accepted the bait paper for publication. The conclusion is that, with respect to non-open access and open access, the probability of accepting pseudoscience is well in favor of this being done by a non-open access journal. Since this interpretation is based on some facts that were not included in the project itself, the only warranted result of this study would be that nothing could be concluded from it. It is concluded that the method that Bohannon used was heavily flawed and in addition immoral; that the report that was published by Science was inconclusive and that the act of publishing such report cannot be morally justified either. Various methods to improve the quality of published papers exist but scientific fraud with "good intentions" as a method to promote scientific publishing should be avoided.
- Numerical analysis of 3D blood flow and common carotid artery hemodynamics in the carotid artery bifurcation with stenosis. [JOURNAL ARTICLE]
- Clin Hemorheol Microcirc 2014 Feb 28.
The results for blood flow in the carotid artery bifurcation on the basis of numerical simulation of Navier-Stokes equations are presented in this study. Four cases of carotid bifurcation are considered: common carotid artery (CCA) bifurcation without stenoses and with one, two and three stenoses are presented too. The results are found by performing numerical simulations considering one pulse wave period based on the finite volume discretization of Navier-Stokes equations. The structures of the flow around the bifurcation are received. Using the numerical simulation the authors can trace the deformation of the pulse wave from common the carotid artery (CCA) to the internal carotid artery (ICA) and external carotid artery (ECA). The axial velocity and wall shear stress (WSS) distribution and contours are presented considering the characteristic time points. The results of the WSS distribution around the bifurcation allow a prediction of the probable sites of stenosis growth.
- Interaction of poly(ether imide) films with early immune mechanisms. [JOURNAL ARTICLE]
- Clin Hemorheol Microcirc 2014 Feb 28.
With the worldwide increase of atherosclerosis, the need for new engineered patient specific implants such as stents or vascular grafts is still emerging. Recently, very smooth poly(ether imide) (PEI) films were, based on their excellent hemocompatibility and compatibility with endothelial cells, suggested as potential biomaterial for cardiovascular applications. In atherosclerosis, immune mechanisms such as complement activation, but also cellular responses such as monocytes and neutrophils activation, can mediate the inflammatory response. Therefore, it is important that the implant material itself does not trigger the inflammatory response. Early immune mechanisms - e.g. macrophage activation, complement induction, generation of reactive oxygen species (ROS), and the secretion of inflammatory cytokines by leukocytes - could potentiate the inflammatory responses, and may thereby alter endothelial cells behaviour or facilitate platelet activation. Therefore, it is important to evaluate the immuno-compatibility of PEI-films. The PEI-films were fabricated from commercially available PEI, which was dissolved in dichloromethane and pulled out on a cleaned, smooth glass surface and subsequently, solvent residues were removed during the drying procedure. Using a murine macrophage reporter cell line possible material bound microbial contaminations and material intrinsic immuno-stimulatory properties were investigated. The macrophages were viable after adhering on the PEI-films and did not show signs of activation, indicating that the used PEI-film was free of microbial contaminations. To determine whether PEI-films induced complement activation, the release of C5a in pooled human plasma was analyzed. The detected C5a levels did not differ between PEI-films and tissue culture plates (TCP), which served as control material. Furthermore, in whole human blood, the generation of ROS as well as the cytokine production were investigated by flow cytometry and by multiplex bead arrays, respectively. The production of IL-6 and TNF-α as well as the generation of ROS by immune cells of the whole blood was not induced upon contact with PEI-films. The immunological evaluation of PEI-films revealed that no substantial activation of the investigated early immune mechanisms occurred. Altogether, this data demonstrate that PEI is immuno-compatible and from that perspective may be a suitable biomaterial for cardiovascular applications.