| 1. |
- Hansson, Kenny, 1972-, et al.
(författare)
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Comparative studies with surface plasmon resonance and free oscillation rheometry on the inhibition of platelets with cytochalasin E and monoclonal antibodies towards GPIIb/IIIa
- 2002
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Ingår i: Biosensors & bioelectronics. - 0956-5663 .- 1873-4235. ; 17:9, s. 761-771
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Tidskriftsartikel (refereegranskat)abstract
- In the haemostatic system a multitude of processes are intertwined in fine-tuned interactions that arrest bleeding, keep the circulatory system open, and the blood flowing. The occurrence of both surface and bulk interactions adds an additional dimension of complexity. These insights have led to the belief that global overall procedures can inform on the likely behaviour of the system in health and disease. Two sensing procedures: surface plasmon resonance (SPR), which senses surface interactions, and free oscillation rheometry (FOR), which senses interactions within the bulk, have been combined and evaluated. The contribution of blood cells, mainly platelets, to the SPR and FOR signals was explored by simultaneous SPR and FOR measurement during native whole blood coagulation, accelerated via the platelets through addition of SFLLRN peptide and inhibition of platelet aggregation with abciximab (ReoPro®) and of shape change with cytochalasin E. The SPR technique was found to be sensitive to inhibition of blood cell functions such as adhesion to and spreading on surfaces, as well as platelet aggregation. SPR seemed not to be directly sensitive to fibrin polymerisation in coagulating whole blood. The FOR technique detected the coagulation as a bulk phenomenon, i.e. the gelation of the blood due to fibrin formation was detected. The combination of SPR and FOR may therefore be suitable for studies on blood cell functions during coagulation.
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| 2. |
- Hansson, Kenny, 1972-
(författare)
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Real-time analysis of blood coagulation and fibrinolysis : new rheological and optical sensing techniques for diagnosis of haemostatic disorders.
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The haemostatic system has a dual paradoxical function in the body. It should arrest bleeding whenever needed, but also keep the blood flowing in the circulatory system without any obstructing blood clots. The system is complex with maoy intertwined processes that interact to produce a fine-tuned regulation of the performance. In case of malfunction in this regulation there may be an excessive coagulation ability, thrombophilia, or bleeding tendency, haemophilia. These are common disorders in the Western societies and may be lethal. The long-term airo of this work is therefore to improve the laboratory diagnosis of haemostatic disorders, for thrombophilia in particular. To achieve this goal a global approach has been chosen, meaning that the environment in which a blood sample is analysed should mimic the physiology of the haemostatic system to better elucidate the overall situation in a particular individual. A first attempt to assess the susceptibility for tissue plasminogen activator induced lysis and coagulum structure in plasma as markers for deep vein thrombosis showed promising results with 47% abnormals among the DVT patients included in the study. To improve this assay new sensing techniques were needed, since one of the most important conditions included in a global assay is analysis of whole blood, i.e. blood with all types of blood cells present. Whole blood is opaque and excludes the traditional optical methods that have been used for coagulation analysis. Several candidate techniques have been identified and surface plasmon resonance (SPR), quartz crystal microbalance-dissipation (QCM-D), and free oscillation rheometry (FOR) have been evaluated for haemostatic studies in this thesis. SPR is an optical surface sensitive technique that has showed promising results for measurements in blood plasma during coagulation and fibrinolysis and for whole blood coagulation. The SPR responses were sensitive to treatments with heparin and oral anticoagulants, which are substances used to treat thrombosis. QCM-D that is sensitive to mass deposition and viscoelastic changes in the sample at the quartz crystal surface has been tested in combination with SPR and provided new information about the viscoelastic properties of the coagulum, although with similar sensing depth as SPR. The idea of combined sensing techniques was reconsidered and resulted in a combination of SPR and FOR for siroultaneous real-time measurements in a blood sample. FOR is bulk sensitive and probes rheological changes in the sample. The combination was applied in studies of plasma and whole blood coagulation as well as plasma fibrinolysis. Coagulation studies including chemical surface modifications by using thiol-based self-assembled monolayers were also attempted. Finally, the FOR/SPR combination was found to be sensitive to inhibition of platelet aggregation and blood cell shape changes iroplying that studies on the cellular component of the blood is possible. In conclusion, the combination of FOR and SPR is a promising sensing system for an improved global assay for haemostatic disorders.
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| 3. |
- Hansson, Kenny, 1972-, et al.
(författare)
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Surface plasmon resonance and free oscillation rheometry in combination : a useful approach for studies on haemostasis and interactions between whole blood and artificial surfaces
- 2002
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Ingår i: Biosensors & bioelectronics. - 0956-5663 .- 1873-4235. ; 17:9, s. 747-759
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Tidskriftsartikel (refereegranskat)abstract
- In haemostatic and biomaterial research biological processes at surfaces and in the bulk phase of the surface-contacting medium are important. The present work demonstrates the usefulness of the combination of surface plasmon resonance (SPR), sensitive to changes in refractive index at surfaces, and free oscillation rheometry (FOR), sensitive to rheological properties of the bulk, for simultaneous real-time measurements on coagulation and fibrinolysis of blood plasma and coagulation of whole blood. SFLLRN stimulated coagulation of native whole blood presented a higher SPR signal with different appearance than plasma coagulation, while the FOR signals corresponding to plasma and whole blood coagulation were similar. This indicated that the SPR technique was more sensitive to cell-surface interactions than to fibrin formation in whole blood during coagulation, while the FOR technique were equally sensitive to coagulation in whole blood and plasma. Spontaneous coagulation of native whole blood in contact with methyl- and hydroxyl-terminated self-assembled monolayers (SAM) on gold and gold surfaces regenerated after coagulation were also studied. The regenerated gold surfaces displayed the shortest coagulation times, although the contact-activation of blood coagulation for these surfaces was low. The methylated and hydroxylated surfaces were comparable in terms of coagulation activation, while the hydroxylated surfaces presented FOR signals that indicated detaching of the coagulum from the surface. The combination of SPR and FOR is well suited for studies of cell– and protein–surface interactions and simultaneous bulk processes. Possible applications are investigations of blood cell defects in patients and monitoring of native whole blood interactions with artificial surfaces.
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| 4. |
- Vikinge, Trine P., et al.
(författare)
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Blood plasma coagulation studied by surface plasmon resonance
- 2000
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Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668 .- 1560-2281. ; 5:1, s. 51-55
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Tidskriftsartikel (refereegranskat)abstract
- A surface plasmon resonance (SPR) apparatus was used to investigate blood plasma coagulation in real time as a function of thromboplastin and heparin concentrations. The response curves were analyzed by curve fitting to a sigmoid curve equation, followed by extraction of the time constant. Clotting activation by thromboplastin resulted in increased time constant, as compared to spontaneously clotted plasma, in a dose dependent way. Addition of heparin to the thromboplastin-activated plasma counteracted this effect. Atomic force microscopy (AFM) pictures of sensor surfaces dried after completed clotting, revealed differences in fibrin network structures as a function of thromboplastin concentration, and the fiber thickness increased with decreased thromboplastin concentration. The physical reason for the SPR signal observed is ambiguous and is therefore discussed. However, the results summarized in the plots and the fibrin network properties observed by AFM correlate well with present common methods used to analyze blood coagulation.
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| 5. |
- Vikinge, Trine P., et al.
(författare)
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Comparison of surface plasmon resonance and quartz crystal microbalance in the study of whole blood and plasma coagulation
- 2000
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Ingår i: Biosensors & bioelectronics. - 0956-5663 .- 1873-4235. ; 15:11-12, s. 605-613
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Tidskriftsartikel (refereegranskat)abstract
- The coagulation of blood plasma and whole blood was studied with a surface plasmon resonance (SPR) based device and a quartz crystal microbalance instrument with energy dissipation detection (QCM-D). The SPR and QCM-D response signals were similar in shape but differing in time scales, reflecting differences in detection mechanisms. The QCM-D response time was longer than SPR, as a physical coupling of the sample to the substrate is required for molecules to be detected by the QCM-method. Change of sample properties within the evanescent field is sufficient for detection with SPR. Both the SPR signals and the QCM-D frequency and dissipation shifts showed dependency on concentrations of coagulation activator and sensitivity to heparin additions. The ratio of dissipation to frequency shifts, commonly considered to reflect viscoelastic properties of the sample, varied with the concentration of activator in blood plasma but not in whole blood. Additions of heparin to the thromboplastin activated whole blood sample, however, made the ratio variation reoccur. Implications of these observations for the understanding of the blood coagulation processes as well as the potential of the two methods in the clinic and in research are discussed.
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