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  • 1
    Language: English
    In: Analytical chemistry, 15 January 2010, Vol.82(2), pp.658-63
    Description: Monitoring of blood coagulation and fibrinolysis is an important issue in treatment of patients with cardiovascular problems and in surgery when blood gets into contact with artificial surfaces. In this work a new method for measuring the coagulation time (prothrombin time, PT) of human whole-blood samples based on a quartz crystal microbalance (QCM) biosensor is presented. The 10 MHz sensors used in this work respond with a frequency shift to changes in viscosity during blood clot formation. For driving and for readout of the quartz, both a network analyzer and an oscillator circuit were utilized. The sensor surfaces were specifically coated with a thin polyethylene layer. We found that both frequency analysis methods are suitable to measure exact prothrombin times in a very good conformity with a mechanical coagulometer as a reference. The anticoagulant effect of heparin on the prothrombin time was exemplarily shown as well as the reverse effect of the heparin antagonist polybrene. The change of the viscoelastic properties during blood coagulation, reflected by the ratio of frequency and dissipation shifts, is discussed for different dilutions of the whole-blood samples. In conclusion, QCM is a distinguished biosensor technique to determine prothrombin time and to monitor heparin therapy in whole-blood samples. Due to the excellent potential of miniaturization and the availability of direct digital signals, the method is predestinated for incorporation and integration into other devices and is thus opening the field of application for inline coagulation diagnostic in extracorporeal blood circuits.
    Keywords: Prothrombin Time ; Quartz ; Biosensing Techniques -- Methods
    ISSN: 00032700
    E-ISSN: 1520-6882
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  • 2
    Language: English
    In: PLoS ONE, 2012, Vol.7(6), p.e38455
    Description: Extracorporeal circulation (ECC) and hypothermia are used to maintain stable circulatory parameters and improve the ischemia tolerance of patients in cardiac surgery. However, ECC and hypothermia induce activation mechanisms in platelets and leukocytes, which are mediated by the platelet agonist ADP and the phosphoinositide-3-kinase (PI3K) p110β. Under clinical conditions these processes are associated with life-threatening complications including thromboembolism and inflammation. This study analyzes effects of ADP receptor P 2 Y 12 and P 2 Y 1 blockade and PI3K p110β inhibition on platelets and granulocytes during hypothermic ECC. Human blood was treated with the P 2 Y 12 antagonist 2-MeSAMP, the P 2 Y 1 antagonist MRS2179, the PI3K p110β inhibitor TGX-221, combinations thereof, or PBS and propylene glycol (controls). Under static in vitro conditions a concentration-dependent effect regarding the inhibition of ADP-induced platelet activation was found using 2-MeSAMP or TGX-221. Further inhibition of ADP-mediated effects was achieved with MRS2179. Next, blood was circulated in an ex vivo ECC model at 28°C for 30 minutes and various platelet and granulocyte markers were investigated using flow cytometry, ELISA and platelet count analysis. GPIIb/IIIa activation induced by hypothermic ECC was inhibited using TGX-221 alone or in combination with P 2 Y blockers (p〈0.05), while no effect of hypothermic ECC or antiplatelet agents on GPIIb/IIIa and GPIbα expression and von Willebrand factor binding was observed. Sole P 2 Y and PI3K blockade or a combination thereof inhibited P-selectin expression on platelets and platelet-derived microparticles during hypothermic ECC (p〈0.05). P 2 Y blockade alone or combined with TGX-221 prevented ECC-induced platelet-granulocyte aggregate formation (p〈0.05). Platelet adhesion to the ECC surface, platelet loss and Mac-1 expression on granulocytes were inhibited by combined P 2 Y and PI3K blockade (p〈0.05). Combined blockade of P 2 Y 12 , P 2 Y 1 and PI3K p110β completely inhibits hypothermic ECC-induced activation processes. This novel finding warrants further studies and the development of suitable pharmacological agents to decrease ECC- and hypothermia-associated complications in clinical applications.
    Keywords: Research Article ; Biology ; Medicine ; Immunology ; Molecular Biology ; Surgery ; Physiology ; Hematology ; Pharmacology
    E-ISSN: 1932-6203
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  • 3
    Language: English
    In: 2015, Vol.10(8), p.e0135527
    Description: Systemic inflammatory response syndrome (SIRS) is a common complication after cardiovascular surgery that in severe cases can lead to multiple organ dysfunction syndrome and even death. We therefore set out to identify reliable early biomarkers for SIRS in a prospective small patient study for timely intervention. 21 Patients scheduled for planned cardiovascular surgery were recruited in the study, monitored for signs of SIRS and blood samples were taken to investigate biomarkers at pre-assigned time points: day of admission, start of surgery, end of surgery, days 1, 2, 3, 5 and 8 post surgery. Stored plasma and cryopreserved blood samples were analyzed for cytokine expression (IL1β, IL2, IL6, IL8, IL10, TNFα, IFNγ), other pro-inflammatory markers (sCD163, sTREM-1, ESM-1) and response to endotoxin. Acute phase proteins CRP, PCT and pro-inflammatory cytokines IL6 and IL8 were significantly increased (p〈0.001) at the end of surgery in all patients but could not distinguish between groups. Normalization of samples revealed significant increases in IL1β changes (p〈0.05) and decreased responses to endotoxin (p〈0.01) in the SIRS group at the end of surgery. Soluble TREM-1 plasma concentrations were significantly increased in patients with SIRS (p〈0.01). This small scale patient study could show that common sepsis markers PCT, CRP, IL6 and TNFα had low predictive value for early diagnosis of SIRS after cardiovascular surgery. A combination of normalized IL1β plasma levels, responses to endotoxin and soluble TREM-1 plasma concentrations at the end of surgery are predictive markers of SIRS development in this small scale study and could act as an indicator for starting early therapeutic interventions.
    Keywords: Research Article
    E-ISSN: 1932-6203
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  • 4
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  • 5
    In: Circulation, 2011, Vol.123(22), pp.2579-2590
    Description: BACKGROUND—: Recent work has suggested that the formation of platelet-neutrophil complexes (PNCs) aggravates the severity of inflammatory tissue injury. Given the importance of vasodilator-stimulated phosphoprotein (VASP) for platelet function, we pursued the role of VASP on the formation of PNCs and its impact on the extent of myocardial ischemia-reperfusion (IR) injury. METHODS AND RESULTS—: In initial in vitro studies we found that neutrophils facilitated the movement of platelets across endothelial monolayers. Phosphorylation of VASP reduced the formation of PNCs and transendothelial movement of PNCs. During myocardial IR injury, VASP animals demonstrated reduced intravascular formation of PNCs and reduced presence of PNCs within the ischemic myocardial tissue. This was associated with reduced IR injury. Studies using platelet transfer and bone marrow chimeric animals showed that hematopoietic VASP expression was crucial for the intravascular formation of PNCs the presence of PNCs within ischemic myocardial tissue and the extent of myocardial IR injury. Furthermore, phosphorylation of VASP on Ser or Ser reduced intravascular PNC formation and presence of PNCs within ischemic myocardial tissue. This finding was associated with reduced myocardial IR injury. CONCLUSION—: Previously unappreciated, the phosphorylation of VASP performs a key function for the formation of PNCs that is crucially important for the extent of myocardial IR injury.
    Keywords: Medicine ; Anatomy & Physiology;
    ISSN: 0009-7322
    E-ISSN: 15244539
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  • 6
    Language: English
    In: Analytical Chemistry, 03/2010, Vol.82(5), pp.2164-2164
    ISSN: 0003-2700
    E-ISSN: 1520-6882
    Source: American Chemical Society (via CrossRef)
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  • 7
    Language: English
    In: Analytical and Bioanalytical Chemistry, May 15, 2014, Vol.406(14), p.3395(12)
    Description: Implant-related infections are a major challenge in clinical routine because of severe complications, for example infective endocarditis (IE). The purpose of this study was to investigate the real-time interaction of S. gordonii with proteins and cells important in the development of IE, in a flow system, by use of a quartz-crystal microbalance (QCM). Acoustic sensors were biologically modified by preconditioning with sterile saliva, platelet-poor plasma (PPP), or plateletrich plasma (PRP), followed then by perfusion of a bacterial suspension. After perfusion, additional fluorescence and scanning electron microscopic (SEM) studies were performed. The surface structure of S. gordonii was analyzed by atomic force microscopy (AFM). Compared with S. gordonii adhesion on the abiotic sensor surface following normal mass loading indicated by a frequency decrease, adhesion on saliva, PPP, or PRP-conditioned sensors resulted in an increase in frequency. Furthermore, adhesion induced slightly increased damping signals for saliva and PPP-coated sensors but a decrease upon bacterial adhesion to PRP, indicating the formation of a more rigid biofilm. Microscopic analysis confirmed the formation of dense and vital bacterial layers and the aggregation of platelets and bacteria. In conclusion, our study shows that the complex patterns of QCM output data observed are strongly dependent on the biological substrate and adhesionmechanisms of S. gordonii. Overall, QCMsheds new light on the pathways of such severe infections as IE. Keywords Quartz-crystal microbalance * Endocarditis * Bacterial adhesion * Saliva*Platelets * Plasma.
    Keywords: Atomic Force Microscopy – Usage ; Endocarditis – Health Aspects ; Quartz Crystals – Analysis
    ISSN: 1618-2642
    Source: Cengage Learning, Inc.
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  • 8
    Language: English
    In: Analytical and bioanalytical chemistry, May 2014, Vol.406(14), pp.3395-406
    Description: Implant-related infections are a major challenge in clinical routine because of severe complications, for example infective endocarditis (IE). The purpose of this study was to investigate the real-time interaction of S. gordonii with proteins and cells important in the development of IE, in a flow system, by use of a quartz-crystal microbalance (QCM). Acoustic sensors were biologically modified by preconditioning with sterile saliva, platelet-poor plasma (PPP), or platelet-rich plasma (PRP), followed then by perfusion of a bacterial suspension. After perfusion, additional fluorescence and scanning electron microscopic (SEM) studies were performed. The surface structure of S. gordonii was analyzed by atomic force microscopy (AFM). Compared with S. gordonii adhesion on the abiotic sensor surface following normal mass loading indicated by a frequency decrease, adhesion on saliva, PPP, or PRP-conditioned sensors resulted in an increase in frequency. Furthermore, adhesion induced slightly increased damping signals for saliva and PPP-coated sensors but a decrease upon bacterial adhesion to PRP, indicating the formation of a more rigid biofilm. Microscopic analysis confirmed the formation of dense and vital bacterial layers and the aggregation of platelets and bacteria. In conclusion, our study shows that the complex patterns of QCM output data observed are strongly dependent on the biological substrate and adhesion mechanisms of S. gordonii. Overall, QCM sheds new light on the pathways of such severe infections as IE.
    Keywords: Biosensing Techniques ; Blood Platelets -- Metabolism ; Endocarditis -- Diagnosis
    ISSN: 16182642
    E-ISSN: 1618-2650
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  • 9
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  • 10
    Language: English
    In: PLoS ONE, 01 January 2015, Vol.10(11), p.e0143527
    Description: The aim of the study was to explore the prevalence and risk factors for technical-induced hemolysis in adults supported with veno-venous extracorporeal membrane oxygenation (vvECMO) and to analyze the effect of hemolytic episodes on outcome. This was a retrospective, single-center study that included 318 adult patients (Regensburg ECMO Registry, 2009-2014) with acute respiratory failure treated with different modern miniaturized ECMO systems. Free plasma hemoglobin (fHb) was used as indicator for hemolysis. Throughout a cumulative support duration of 4,142 days on ECMO only 1.7% of the fHb levels were above a critical value of 500 mg/l. A grave rise in fHb indicated pumphead thrombosis (n = 8), while acute oxygenator thrombosis (n = 15) did not affect fHb. Replacement of the pumphead normalized fHb within two days. Neither pump or cannula type nor duration on the first system was associated with hemolysis. Multiple trauma, need for kidney replacement therapy, increased daily red blood cell transfusion requirements, and high blood flow (3.0-4.5 L/min) through small-sized cannulas significantly resulted in augmented blood cell trauma. Survivors were characterized by lower peak levels of fHb [90 (60, 142) mg/l] in comparison to non-survivors [148 (91, 256) mg/l, p≤0.001]. In conclusion, marked hemolysis is not common in vvECMO with modern devices. Clinically obvious hemolysis often is caused by pumphead thrombosis. High flow velocity through small cannulas may also cause technical-induced hemolysis. In patients who developed lung failure due to trauma, fHb was elevated independantly of ECMO. In our cohort, the occurance of hemolysis was associated with increased mortality.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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