| 1. |
- Grenegård, Magnus, et al.
(författare)
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The ATP-gated P2X1 receptor plays a pivotal role in activation of aspirin-treated platelets by thrombin and epinephrine
- 2008
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 283:27, s. 18493-18504
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Tidskriftsartikel (refereegranskat)abstract
- Human platelets express protease-activated receptor 1 (PAR1) and PAR4 but limited data indicate for differences in signal transduction. We studied the involvement of PAR1 and PAR4 in the cross-talk between thrombin and epinephrine. The results show that epinephrine acted via alpha(2A)-adrenergic receptors to provoke aggregation, secretion, and Ca(2+) mobilization in aspirin-treated platelets pre-stimulated with subthreshold concentrations of thrombin. Incubating platelets with antibodies against PAR4 or the PAR4-specific inhibitor pepducin P4pal-i1 abolished the aggregation. Furthermore, platelets pre-exposed to the PAR4-activating peptide AYPGKF, but not to the PAR1-activating peptide SFLLRN, were aggregated by epinephrine, whereas both AYPGKF and SFLLRN synergized with epinephrine in the absence of aspirin. The roles of released ATP and ADP were elucidated by using antagonists of the purinergic receptors P2X(1), P2Y(1), and P2Y(12) (i.e. NF449, MRS2159, MRS2179, and cangrelor). Intriguingly, ATP, but not ADP, was required for the epinephrine/thrombin-induced aggregation. In Western blot analysis, a low concentration of AYPGKF, but not SFLLRN, stimulated phosphorylation of Akt on serine 473. Moreover, the phosphatidyl inositide 3-kinase inhibitor LY294002 antagonized the effect of epinephrine combined with thrombin or AYPGKF. Thus, in aspirin-treated platelets, PAR4, but not PAR1, interacts synergistically with alpha(2A)-adrenergic receptors, and the PI3-kinase/Akt pathway is involved in this cross-talk. Furthermore, in PAR4-pretreated platelets, epinephrine caused dense granule secretion, and subsequent signaling from the ATP-gated P2X(1)-receptor and the alpha(2A)-adrenergic receptor induced aggregation. These results suggest a new mechanism that has ATP as a key element and circumvents the action of aspirin on epinephrine-facilitated PAR4-mediated platelet activation.
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| 2. |
- Heiskanen, Arto, et al.
(författare)
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Mediator-assisted simultaneous probing of cytosolic and mitochondrial redox activity in living cells.
- 2009
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 1096-0309 .- 0003-2697. ; 384:1, s. 11-19
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Tidskriftsartikel (refereegranskat)abstract
- This work describes an electron transfer mediator-assisted amperometric flow injection method for assessing redox enzyme activity in different subcellular compartments of the phosphoglucose isomerase deletion mutant strain of Saccharomyces cerevisiae, EBY44. The method is demonstrated using the ferricyanide-menadione double mediator system to study the effect of dicoumarol, an inhibitor of cytosolic and mitochondrial oxidoreductases and an uncoupler of the electron transport chain. Evaluation of the role of NAD(P)H-producing pathways in mediating biological effects is facilitated by introducing either fructose or glucose as the carbon source, yielding either NADH or NADPH through the glycolytic or pentose phosphate pathway, respectively. Respiratory noncompetent cells show greater inhibition of cytosolic menadione-reducing enzymes when NADH rather than NADPH is produced. Spectrophotometric in vitro assays show no difference between the cofactors. Respiratory competent cells show cytosolic inhibition only when NADPH is produced, whereas production of NADH reveals uncoupling at low dicoumarol concentrations and inhibition of complexes III and IV at higher concentrations. Spectrophotometric assays only indicate the presence of cytosolic inhibition regardless of the reduced cofactor used. This article shows the applicability of the amperometric method and emphasizes the significance of determining biological effects of chemicals in living cells.
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| 3. |
- Helldal, Michael, 1982-, et al.
(författare)
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Environmental benefits riding the coattails of lean production : can an integration of environmental aspects and lean production result in synergies and a reduced risk of sub-opimisation
- 2009
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Ingår i: Proceedings of EcoDesign 2009. - Sapporo, Japan.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this study was to investigate how work with Lean and environmental aspects affect one another, and if possible and beneficial from a business point-of-view, how they could be integrated into a single model.It was found that several of the fundamental concepts concerning Lean and environmental aspects support one another. Further, Lean has the potential to improve the environmental performance of a company, and can contributeto the environmental work by its proactive approach, structured way of operating and long-term way of thinking. The environmental perspective can contribute to Lean with its more holistic view; additional cost savingsand improvements might be found when looking at the operations from an environmental point-of-view.The study showed that it is not only possible to integrate Lean and environmental work, but that it also has the potential to be beneficial from both a business and an environmental standpoint. Integration can reduce the risk of sub-optimization, and synergies can be achieved. With this knowledge, the authors composed a model for how Lean and environmental work can be practised and integrated.
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| 4. |
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| 5. |
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| 6. |
- Lindahl, Tomas L, et al.
(författare)
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Methods for evaluation of platelet function.
- 2009
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Ingår i: Transfusion and apheresis science. - : Elsevier BV. - 1473-0502 .- 1878-1683. ; 41:2, s. 121-125
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Tidskriftsartikel (refereegranskat)abstract
- There are a multitude of platelet function tests available, reflecting the complex nature of the platelet in haemostasis. No simple single test will ever cover all aspects of platelet function. Some tests focus on the aggregation of platelets, for example aggregometry, other on the swelling in response to hypotonic solutions, i.e. the well-known hypotonic shock response, or adhesion or coagulation and clot retraction, for example thromboelastography. In general there is a lack of clinical studies showing a predictive value of analysis of platelet concentrates.
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| 7. |
- Persdotter, Sofia, et al.
(författare)
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Cooperative inhibitory effects of budesonide and formoterol on eosinophil superoxide production stimulated by bronchial epithelial cell conditioned medium
- 2007
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Ingår i: International Archives of Allergy and Immunology. - : S. Karger AG. - 1423-0097 .- 1018-2438. ; 143:3, s. 201-210
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Tidskriftsartikel (refereegranskat)abstract
- Background: Improved asthma control by combinations of inhaled glucocorticosteroids (GCs) and long-acting beta(2)-agonists (LABAs) includes a reduced frequency and severity of exacerbations. In view of the association of exacerbations with increased airway inflammation, the question has arisen as to whether LABAs are able to complement the known anti- inflammatory activity of GCs. To address this, we studied the effects of a LABA, formoterol (FORM), and a GC, budesonide (BUD), alone and in combination, on bronchial epithelial cell-mediated eosinophil superoxide production in vitro. Methods: We employed 2 experimental approaches. First, superoxide production by human eosinophils incubated with conditioned medium (CM) from human bronchial epithelial cells cultured for 24 h with vehicle, BUD, FORM or BUD + FORM was measured (Epi/Eos assay). Second, eosinophils were stimulated with vehicle-CM to which the drugs were added (Eos assay). Superoxide production was determined as the superoxide dismutase-inhibitable reduction of ferricytochrome C. Results: CM increased eosinophil superoxide generation (p < 0.01) and epithelial-derived granulocyte macrophage colony-stimulating factor was the mediator responsible. In both assays, FORM dose-dependently inhibited eosinophil superoxide similarly and in the same concentration range as BUD. The BUD + FORM combination was more effective than BUD alone, and it completely inhibited CM-induced superoxide production in the Epi/Eos assay, suggesting complementary effects of both drugs on bronchial epithelial cells and eosinophils. Conclusions: The cooperative, inhibitory effects of BUD and FORM on eosinophils and bronchial epithelial cells, in terms of their effects on eosinophil superoxide production, may represent a possible mechanism for the enhanced anti-inflammatory efficacy of BUD and FORM combination therapy of asthma. Copyright (c) 2007 S. Karger AG, Basel
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| 8. |
- Ramström, Sofia, 1973-, et al.
(författare)
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Platelet PAR1 receptor density-Correlation to platelet activation response and changes in exposure after platelet activation
- 2008
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Ingår i: Thrombosis Research. - : Elsevier BV. - 0049-3848 .- 1879-2472. ; 121:5, s. 681-688
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: A polymorphism (-14 A/T) affecting PAR1 expression on the platelet surface has recently been identified. A two-fold variation in receptor density, which correlated with the platelet response to PAR1-activating peptide (PAR1-AP), has been reported. Materials and methods: We used flow cytometry to measure the correlation between the number of PAR1 receptors and platelet activation. We also measured the changes in receptor exposure after platelet activation with PAR1-AP, ADP, PAR4-AP or a collagen-related peptide (CRP). Results: In our study, the PAR1 receptor number varied almost four-fold, from 547 to 2063 copies/platelet (mean ± S.D. 1276 ± 320, n = 70). The number of PAR1 receptors on resting platelets correlated to platelet fibrinogen binding and P-selectin expression following platelet activation with PAR1-AP (r2 = 0.30, p < 0.01 and r2 = 0.15, p < 0.05, respectively, n = 36). The correlation was not improved by exclusion of the ADP-component from the PAR1-AP-induced response. We found a trend, but no statistically significant differences in PAR1 receptor number and platelet reactivity between A/A individuals and T/A or T/T individuals. Ex vivo activation with PAR1-AP decreased PAR1 surface exposure to 71 ± 19% of the exposure on resting platelets (mean ± S.D., p < 0.01, n = 19), while activation by ADP, PAR4-AP or CRP significantly increased the exposure, to 151 ± 27%, 120 ± 21% and 138 ± 25%, respectively (n = 11, 11 and 10). Conclusions: This study shows a large variation in PAR1 receptor number in healthy individuals, a variation correlated to the platelet activation response. We found a significant reduction in PAR1 surface exposure after adding PAR1-AP, while activation with ADP, PAR4-AP or CRP increased the exposure.
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| 9. |
- Tynngård, Nahreen, et al.
(författare)
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Effects of different blood components on clot retraction analysed by measuring elasticity with a free oscillating rheometer
- 2006
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Ingår i: Platelets. - : Informa UK Limited. - 0953-7104 .- 1369-1635. ; 17:8, s. 545-554
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Tidskriftsartikel (refereegranskat)abstract
- Free oscillation rheometry (FOR) using the ReoRox® 4 instrument makes it possible, at bedside, to study the coagulation process in blood over time and gives information on clotting time and coagulum elastic properties. In order to find out how various factors influence the FOR analysis we studied the coagulation process and change of elasticity over time in non-anticoagulated and citrated blood samples, plasma samples with various platelet concentrations (0-200 109/l) and blood samples with various haematocrit (0-40%). Blood samples supplemented with fibrinogen were analysed to elucidate the importance of fibrinogen on elasticity. The importance of the GPIIb/IIIa receptor on platelets was investigated by comparing the elasticity development in blood samples in presence and absence of a GPIIb/IIIa receptor inhibitor, abciximab. Anticoagulation with citrate did not have major influence on the viscoelastic properties of the coagulum. Increasing number of platelets and increasing fibrinogen concentration resulted in higher elasticity while increasing haematocrit gave lower elasticity. Blood samples with GPIIb/IIIa receptor inhibitor had very low elasticity indicating the importance of functional GPIIb/IIIa receptors. In conclusion we consider FOR to be a useful method to study the elastic properties of the coagulum. Various factors such as the number of red blood cells and platelets as well as the fibrinogen concentration should be taken into consideration when evaluating the results. The ReoRox® 4 instrument had excellent measuring range and unusually small artefactual effects on clot elasticity induced by the instrument in comparison with published results on other instruments.
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| 10. |
- Tynngård, Nahreen, et al.
(författare)
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Free oscillation rheometry detects changes in clot properties in pregnancy and thrombocytopaenia
- 2008
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Ingår i: Platelets. - : Informa UK Limited. - 0953-7104 .- 1369-1635. ; 19:5, s. 373-378
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Tidskriftsartikel (refereegranskat)abstract
- Improved methods are needed to identify patients at risk for thrombotic or bleeding events. Free oscillation rheometry (FOR) is a technique that offers information on coagulation, based on contributions of all blood components, by measurement of clotting time and changes in clot elasticity. This is the first study that evaluates FOR parameters in subjects likely to represent hypercoagulability (pregnant women) and hypocoagulability (thrombocytopenic patients). Clotting time and blood clot elasticity were measured by FOR in blood samples obtained from women in different pregnancy trimesters (n = 58), in thrombocytopenic patients before and after a platelet transfusion (n = 20) and in healthy blood donors (n = 60). The clotting time was shorter and the clot elasticity higher in pregnant women compared to the non-pregnant female blood donors. The elasticity was higher in late pregnancy compared to early pregnancy. Compared to the blood donors, the thrombocytopenic patients had lower elasticity, which was increased by a platelet transfusion, but there was no difference in clotting time. The results suggest that FOR can provide new information on the haemostatic status of patients at risk of thrombotic or bleeding events as well as information on the haemostatic effect of a platelet transfusion.
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