| 1. |
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| 2. |
- Braun, Oscar, et al.
(författare)
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Residual platelet ADP reactivity after clopidogrel treatment is dependent on activation of both the unblocked P2Y(1) and the P2Y (12) receptor and is correlated with protein expression of P2Y (12).
- 2007
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Ingår i: Purinergic Signalling. - : Springer Science and Business Media LLC. - 1573-9546 .- 1573-9538. ; 3:3, s. 195-201
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Tidskriftsartikel (refereegranskat)abstract
- Two ADP receptors have been identified on human platelets: P2Y(1) and P2Y(12). The P2Y(12) receptor blocker clopidogrel is widely used to reduce the risks in acute coronary syndromes, but, currently, there is no P2Y(1) blocker in clinical use. Evidence for variable responses to clopidogrel has been described in several reports. The mechanistic explanation for this phenomenon is not fully understood. The aim of this study was to examine mechanisms responsible for variability of 2MeS-ADP, a stable ADP analogue, induced platelet reactivity in clopidogrel-treated patients. Platelet reactivity was assessed by flow cytometry measurements of P-selectin (CD62P) and activated GpIIb/IIIa complex (PAC-1). Residual 2MeS-ADP activation via the P2Y(12) and P2Y(1) receptors was determined by co-incubation with the selective antagonists AR-C69931 and MRS2179 in vitro. P2Y(1) and P2Y(12) receptor expression on both RNA and protein level were determined, as well as the P2Y(12) H1 or H2 haplotypes. Our data suggest that the residual platelet activation of 2MeS-ADP after clopidogrel treatment is partly due to an inadequate antagonistic effect of clopidogrel on the P2Y(12) receptor and partly due to activation of the P2Y(1) receptor, which is unaffected by clopidogrel. Moreover, a correlation between increased P2Y(12) protein expression on platelets and decreased response to clopidogrel was noticed, r(2)=0.43 (P<0.05). No correlation was found between P2Y(12) mRNA levels and clopidogrel resistance, indicating post-transcriptional mechanisms. To achieve additional ADP inhibition in platelets, antagonists directed at the P2Y(1) receptor could be more promising than the development of more potent P2Y(12) receptor antagonists.
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| 3. |
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| 4. |
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| 5. |
- Castro, C. M., et al.
(författare)
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Adenosine A2A receptor null chondrocyte transcriptome resembles that of human osteoarthritic chondrocytes
- 2021
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Ingår i: Purinergic Signalling. - : Springer Science and Business Media LLC. - 1573-9538 .- 1573-9546. ; 17, s. 439-448
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Tidskriftsartikel (refereegranskat)abstract
- Adenosine signaling plays a critical role in the maintenance of articular cartilage and may serve as a novel therapeutic for osteoarthritis (OA), a highly prevalent and morbid disease without effective therapeutics in the current market. Mice lacking adenosine A2A receptors (A2AR) develop spontaneous OA by 16 weeks of age, a finding relevant to human OA since loss of adenosine signaling due to diminished adenosine production (NT5E deficiency) also leads to development of OA in mice and humans. To better understand the mechanism by which A2AR and adenosine generation protect from OA development, we examined differential gene expression in neonatal chondrocytes from WT and A2AR null mice. Analysis of differentially expressed genes was analyzed by KEGG pathway analysis, and oPOSSUM and the flatiron database were used to identify transcription factor binding enrichment, and tissue-specific network analyses and patterns were compared to gene expression patterns in chondrocytes from patients with OA. There was a differential expression of 2211 genes (padj<0.05). Pathway enrichment analysis revealed that pro-inflammatory changes, increased metalloprotease, reduced matrix organization, and homeostasis are upregulated in A2AR null chondrocytes. Moreover, stress responses, including autophagy and HIF-1 signaling, seem to be important drivers of OA and bear marked resemblance to the human OA transcriptome. Although A2AR null mice are born with grossly intact articular cartilage, we identify here the molecular foundations for early-onset OA in these mice, further establishing their role as models for human disease and the potential use of adenosine as a treatment for human disease.
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| 6. |
- Chizhmakov, Igor, et al.
(författare)
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Molecular mechanism for opioid dichotomy : bidirectional effect of mu-opioid receptors on P2X(3) receptor currents in rat sensory neurones
- 2015
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Ingår i: Purinergic Signalling Purinergic Signalling. - : Springer Science and Business Media LLC. - 1573-9538 .- 1573-9546. ; 11:2, s. 171-181
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Tidskriftsartikel (refereegranskat)abstract
- Here, we describe a molecular switch associated with opioid receptors-linked signalling cascades that provides a dual opioid control over P2X(3) purinoceptor in sensory neurones. Leu-enkephalin inhibited P2X(3)-mediated currents with IC50 similar to 10 nM in similar to 25 % of small nociceptive rat dorsal root ganglion (DRG) neurones. In contrast, in neurones pretreated with pertussis toxin leu-enkephalin produced stable and significant increase of P2X(3) currents. All effects of opioid were abolished by selective mu-opioid receptor antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP), nonselective inhibitor naloxone, and by PLC inhibitor U73122. Thus, we discovered a dual link between purinoceptors and mu-opioid receptors: the latter exert both inhibitory (pertussis toxin-sensitive) and stimulatory (pertussis toxin-insensitive) actions on P2X(3) receptors through phospholipase C (PLC)-dependent pathways. This dual opioid control of P2X(3) receptors may provide a molecular explanation for dichotomy of opioid therapy. Pharmacological control of this newly identified facilitation/inhibition switch may open new perspectives for the adequate medical use of opioids, the most powerful pain-killing agents known today.
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| 7. |
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| 8. |
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| 9. |
- Erlinge, David
(författare)
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P2-polymorphisms and cardiovascular disease
- 2008
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Ingår i: Purinergic Signalling. - : Springer Science and Business Media LLC. - 1573-9546 .- 1573-9538. ; 4:S1, s. 135-135
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Konferensbidrag (refereegranskat)
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| 10. |
- Erlinge, David, et al.
(författare)
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P2 receptors in cardiovascular regulation and disease.
- 2008
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Ingår i: Purinergic Signalling. - : Springer Science and Business Media LLC. - 1573-9546 .- 1573-9538. ; 4:1, s. 1-20
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Tidskriftsartikel (refereegranskat)abstract
- The role of ATP as an extracellular signalling molecule is now well established and evidence is accumulating that ATP and other nucleotides (ADP, UTP and UDP) play important roles in cardiovascular physiology and pathophysiology, acting via P2X (ion channel) and P2Y (G protein-coupled) receptors. In this article we consider the dual role of ATP in regulation of vascular tone, released as a cotransmitter from sympathetic nerves or released in the vascular lumen in response to changes in blood flow and hypoxia. Further, purinergic long-term trophic and inflammatory signalling is described in cell proliferation, differentiation, migration and death in angiogenesis, vascular remodelling, restenosis and atherosclerosis. The effects on haemostasis and cardiac regulation is reviewed. The involvement of ATP in vascular diseases such as thrombosis, hypertension and diabetes will also be discussed, as well as various heart conditions. The purinergic system may be of similar importance as the sympathetic and renin-angiotensin-aldosterone systems in cardiovascular regulation and pathophysiology. The extracellular nucleotides and their cardiovascular P2 receptors are now entering the phase of clinical development.
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| 11. |
- Ferreira, Raphael, 1990, et al.
(författare)
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Photoswitch kinase inhibitors
- 2014
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Ingår i: Purinergic Signalling. - 1573-9538 .- 1573-9546. ; 10:4, s. 767-768
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 12. |
- Fredholm, BB
(författare)
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Some reflections after a long life in science
- 2024
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Ingår i: Purinergic signalling. - : Springer Science and Business Media LLC. - 1573-9546 .- 1573-9538. ; 20:2, s. 207-208
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 13. |
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| 14. |
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| 15. |
- Kruse, Robert, 1972-, et al.
(författare)
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IL-8 and global gene expression analysis define a key role of ATP in renal epithelial cell responses induced by uropathogenic bacteria
- 2014
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Ingår i: Purinergic Signalling Purinergic Signalling. - Dordrect, Netherlands : Springer. - 1573-9538 .- 1573-9546. ; 10:3, s. 499-508
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Tidskriftsartikel (refereegranskat)abstract
- The recent recognition of receptor-mediated ATP signalling as a pathway of epithelial pro-inflammatory cytokine release challenges the ubiquitous role of the TLR4 pathway during urinary tract infection. The aim of this study was to compare cellular responses of renal epithelial cells infected with uropathogenic Escherichia coli (UPEC) strain IA2 to stimulation with ATP-gamma-S. A498 cells were infected or stimulated in the presence or absence of apyrase, that degrades extracellular ATP, or after siRNA-mediated knockdown of ATP-responding P2Y(2) receptors. Cellular IL-8 release and global gene expression were analysed. Both IA2 and A498 cells per se released ATP, which increased during infection. IA2 and ATP-gamma-S caused a similar to 5-fold increase in cellular release of IL-8 and stimulations performed in the presence of apyrase or after siRNA knockdown of P2Y(2) receptors resulted in attenuation of IA2-mediated IL-8 release. Microarray results show that both IA2 and ATP-gamma-S induced marked changes in gene expression of renal cells. Thirty-six genes were in common between both stimuli, and many of these are key genes belonging to classical response pathways of bacterial infection. Functional analysis shows that 88 biological function-annotated cellular pathways were identical between IA2 and ATP-gamma-S stimuli. Results show that UPEC-induced release of IL-8 is dependent on P2Y(2) signalling and that cellular responses elicited by UPEC and ATP-gamma-S have many identical features. This indicates that renal epithelial responses elicited by bacteria could be mediated by bacteria- or host-derived ATP, thus defining a key role of ATP during infection.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Olivecrona, Göran, et al.
(författare)
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Coronary artery reperfusion: The ADP receptor P2Y(1) mediates early reactive hyperemia in vivo in pigs.
- 2004
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Ingår i: Purinergic Signalling. - : Springer Science and Business Media LLC. - 1573-9546 .- 1573-9538. ; 1:1, s. 59-65
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Tidskriftsartikel (refereegranskat)abstract
- The physiological mechanisms that regulate reactive hyperemia are not fully understood. We postulated that the endothelial P2Y(1) receptor that release vasodilatory factors in response to ADP might play a vital role in the regulation of coronary flow. Intracoronary flow was measured with a Doppler flow-wire in a porcine model. 2-MeSADP (10(-5) M), ATP (10(-4) M) or UTP (10(-4) M) alone or as co-infusion with a selective P2Y(1) receptor blocker, MRS 2179 (10(-3) M) was locally delivered through the tip of a coronary angioplasty balloon. In separate pigs the coronary artery was occluded with the balloon for 10 min. During the first and tenth minutes of coronary ischemia, 2.5 ml of MRS 2179 (10(-3) M) was delivered distal to the occlusion in 8 pigs, 10 pigs were used as controls. MRS 2179 fully inhibited the 2-MeSADP-mediated coronary flow increase (P < 0.05) with no effect on UTP, indicating selective P2Y(1) inhibition. ATP-mediated flow increase was significantly inhibited by MRS 2179. During reactive hyperemia following coronary occlusion, flow increased by nearly sevenfold. MRS 2179, however, reduced the post-ischemic hyperemia by a mean of 46% during the period 1-2.5 min following balloon deflation (P < 0.05), which corresponds to peak velocity flow during reperfusion. In conclusion, MRS 2179, a selective P2Y(1) receptor blocker, significantly reduces the increased coronary flow caused both by 2-MeSADP and reactive hyperemia in coronary arteries. Thus, ADP acting on the endothelial P2Y(1) receptor may play a major role in coronary flow during post-ischemic hyperemia.
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| 20. |
- Sathanoori, Ramasri, et al.
(författare)
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Shear stress modulates endothelial KLF2 through activation of P2X4.
- 2015
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Ingår i: Purinergic Signalling. - : Springer Science and Business Media LLC. - 1573-9546 .- 1573-9538. ; 11:1, s. 139-153
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Tidskriftsartikel (refereegranskat)abstract
- Vascular endothelial cells that are in direct contact with blood flow are exposed to fluid shear stress and regulate vascular homeostasis. Studies report endothelial cells to release ATP in response to shear stress that in turn modulates cellular functions via P2 receptors with P2X4 mediating shear stress-induced calcium signaling and vasodilation. A recent study shows that a loss-of-function polymorphism in the human P2X4 resulting in a Tyr315>Cys variant is associated with increased pulse pressure and impaired endothelial vasodilation. Although the importance of shear stress-induced Krüppel-like factor 2 (KLF2) expression in atheroprotection is well studied, whether ATP regulates KLF2 remains unanswered and is the objective of this study. Using an in vitro model, we show that in human umbilical vein endothelial cells (HUVECs), apyrase decreased shear stress-induced KLF2, KLF4, and NOS3 expression but not that of NFE2L2. Exposure of HUVECs either to shear stress or ATPγS under static conditions increased KLF2 in a P2X4-dependent manner as was evident with both the receptor antagonist and siRNA knockdown. Furthermore, transient transfection of static cultures of human endothelial cells with the Tyr315>Cys mutant P2X4 construct blocked ATP-induced KLF2 expression. Also, P2X4 mediated the shear stress-induced phosphorylation of extracellular regulated kinase-5, a known regulator of KLF2. This study demonstrates a major physiological finding that the shear-induced effects on endothelial KLF2 axis are in part dependent on ATP release and P2X4, a previously unidentified mechanism.
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| 21. |
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| 22. |
- Tan, Chanyuan, et al.
(författare)
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High glucose and free fatty acids induce beta cell apoptosis via autocrine effects of ADP acting on the P2Y(13) receptor.
- 2013
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Ingår i: Purinergic Signalling. - : Springer Science and Business Media LLC. - 1573-9546 .- 1573-9538. ; 9:1, s. 67-79
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Tidskriftsartikel (refereegranskat)abstract
- While high levels of glucose and saturated fatty acids are known to have detrimental effects on beta cell function and survival, the signalling pathways mediating these effects are not entirely known. In a previous study, we found that ADP regulates beta cell insulin secretion and beta cell apoptosis. Using MIN6c4 cells as a model system, we investigated if autocrine/paracrine mechanisms of ADP and purinergic receptors are involved in this process. High glucose (16.7 mmol/l) and palmitate (100 μmol/l) rapidly and potently elevated the extracellular ATP levels, while mannitol was without effect. Both tolbutamide and diazoxide were without effect, while the calcium channel blocker nifedipine, the volume-regulated anion channels (VRAC) inhibitor NPPB, and the pannexin inhibitor carbenoxolone could inhibit both effects. Similarly, silencing the MDR1 gene also blocked nutrient-generated ATP release. These results indicate that calcium channels and VRAC might be involved in the ATP release mechanism. Furthermore, high glucose and palmitate inhibited cAMP production, reduced cell proliferation in MIN6c4 and increased activated Caspase-3 cells in mouse islets and in MIN6c4 cells. The P2Y(13)-specific antagonist MRS2211 antagonized all these effects. Further studies showed that blocking the P2Y(13) receptor resulted in enhanced CREB, Bad and IRS-1 phosphorylation, which are known to be involved in beta cell survival and insulin secretion. These findings provide further support for the concept that P2Y(13) plays an important role in beta cell apoptosis and suggest that autocrine/paracrine mechanisms, related to ADP and P2Y(13) receptors, contribute to glucolipotoxicity.
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| 23. |
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| 24. |
- Voss, Ulrikke, et al.
(författare)
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The enteric nervous system of P2Y13 receptor null mice is resistant against high-fat-diet- and palmitic-acid-induced neuronal loss.
- 2014
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Ingår i: Purinergic Signalling. - : Springer Science and Business Media LLC. - 1573-9546 .- 1573-9538. ; 10:3, s. 455-464
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Tidskriftsartikel (refereegranskat)abstract
- Gastrointestinal symptoms have a major impact on the quality of life and are becoming more prevalent in the western population. The enteric nervous system (ENS) is pivotal in regulating gastrointestinal functions. Purinergic neurotransmission conveys a range of short and long-term cellular effects. This study investigated the role of the ADP-sensitive P2Y13 receptor in lipid-induced enteric neuropathy. Littermate P2Y13 (+/+) and P2Y13 (-/-) mice were fed with either a normal diet (ND) or high-fat diet (HFD) for 6 months. The intestines were analysed for morphological changes as well as neuronal numbers and relative numbers of vasoactive intestinal peptide (VIP)- and neuronal nitric oxide synthase (nNOS)-containing neurons. Primary cultures of myenteric neurons from the small intestine of P2Y13 (+/+) or P2Y13 (-/-) mice were exposed to palmitic acid (PA), the P2Y13 receptor agonist 2meSADP and the antagonist MRS2211. Neuronal survival and relative number of VIP-containing neurons were analysed. In P2Y13 (+/+), but not in P2Y13 (-/-) mice, HFD caused a significant loss of myenteric neurons in both ileum and colon. In colon, the relative numbers of VIP-containing submucous neurons were significantly lower in the P2Y13 (-/-) mice compared with P2Y13 (+/+) mice. The relative numbers of nNOS-containing submucous colonic neurons increased in P2Y13 (+/+) HFD mice. HFD also caused ileal mucosal thinning in P2Y13 (+/+) and P2Y13 (-/-) mice, compared to ND fed mice. In vitro PA exposure caused loss of myenteric neurons from P2Y13 (+/+) mice while neurons from P2Y13 (-/-) mice were unaffected. Presence of MRS2211 prevented PA-induced neuronal loss in cultures from P2Y13 (+/+) mice. 2meSADP caused no change in survival of cultured neurons. P2Y13 receptor activation is of crucial importance in mediating the HFD- and PA-induced myenteric neuronal loss in mice. In addition, the results indicate a constitutive activation of enteric neuronal apoptosis by way of P2Y13 receptor stimulation.
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| 25. |
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| 26. |
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| 27. |
- Zhou, ZC
(författare)
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Purinergic interplay between erythrocytes and platelets in diabetes-associated vascular dysfunction
- 2021
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Ingår i: Purinergic signalling. - : Springer Science and Business Media LLC. - 1573-9546 .- 1573-9538. ; 17:4, s. 705-712
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Tidskriftsartikel (refereegranskat)abstract
- Cardiovascular complications in diabetes are the leading causes for high morbidity and mortality. It has been shown that alteration of purinergic signaling contributes to diabetes-associated cardiovascular complications. Red blood cells (RBCs) and platelets play a fundamental role in regulation of oxygen transport and hemostasis, respectively. Of note, these cells undergo purinergic dysfunction in diabetes. Recent studies have established a novel function of RBCs as disease mediators for the development of endothelial dysfunction in type 2 diabetes (T2D). RBC-released ATP is defective in T2D, which has implication for induction of vascular dysfunction by dysregulating purinergic signaling. Platelets are hyperactive in diabetes. ADP-mediated P2Y1 and P2Y12 receptor activation contributes to platelet aggregation and targeting P2Y receptors particularly P2Y12 receptor in platelets is effective for the treatment of cardiovascular events. In contrast to other P2Y12 receptor antagonists, platelet-targeting drug ticagrelor has potential to initiate purinergic signaling in RBCs for the beneficial cardiovascular outcomes. It is increasingly clear that altered vascular purinergic signaling mediated by various nucleotides and nucleoside contributes to diabetes-associated vascular dysfunction. However, the contribution of complex purinergic networks between RBCs and platelets to the vascular dysfunction in diabetes remains unclear. This study discusses the possible interplay of RBCs and platelets via the purinergic network for diabetes-associated vascular dysfunction.
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| 28. |
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| 29. |
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| 30. |
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| 31. |
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| 32. |
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| 33. |
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| 34. |
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| 35. |
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| 36. |
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| 37. |
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| 38. |
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| 39. |
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| 40. |
- Johannesson, Björn, et al.
(författare)
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A Numerical Approach for Non-Linear Moisture Flow in Porous Materials with Account to Sorption Hysteresis
- 2010
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Ingår i: Transport in Porous Media. - : Springer Science and Business Media LLC. - 0169-3913 .- 1573-1634. ; 84:3, s. 735-754
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Tidskriftsartikel (refereegranskat)abstract
- A numerical approach for moisture transport in porous materials like concrete is presented. The model considers mass balance equations for the vapour phase and the water phase in the material together with constitutive equations for the mass flows and for the exchange of mass between the two phases. History-dependent sorption behaviour is introduced by considering scanning curves between the bounding desorption and absorption curves. The method, therefore, makes it possible to calculate equilibrium water contents for arbitrary relative humidity variations at every material point considered. The scanning curves for different wetting and drying conditions are constructed by using third degree polynomial expressions. The three coefficients describing the scanning curves is determined for each wetting and drying case by assuming a relation between the slope of boundary sorption curve and the scanning curve at the point where the moisture response enters the scanning domain. Furthermore, assuming that the slope of the scanning curve is the same as the boundary curve at the junction point, that is, at the point where the scanning curve hits the boundary curve once leaving the scanning domain, a complete cyclic behaviour can be considered. A finite element approach is described, which is capable of solving the non-linear coupled equation system. The numerical calculation is based on a Taylor expansion of the residual of the stated problem together with the establishment of a Newton-Raphson equilibrium iteration scheme within the time steps. Examples are presented illustrating the performance and potential of the model. Two different types of measurements on moisture content profiles in concrete are used to verify the relevance of the novel proposed model for moisture transport and sorption. It is shown that a good match between experimental results and model predictions can be obtained by fitting the included material constants and parameters.
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| 41. |
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| 42. |
- Hellström, Kristina M, 1971, et al.
(författare)
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The Oxide Scales Formed on a Dispersion-Strengthened Powder Metallurgical FeCrAl Alloy at 900 A degrees C in O-2 and in O-2 + H2O
- 2015
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Ingår i: Oxidation of Metals. - : Springer Science and Business Media LLC. - 1573-4889 .- 0030-770X. ; 84:1-2, s. 1-19
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Tidskriftsartikel (refereegranskat)abstract
- Early oxide scale growth on an oxide dispersion strengthened rapidly solidified powder FeCrAl material, Kanthal(A (R)) APMT, was investigated at 900 A degrees C in an O-2 + N-2 and an O-2 + H2O + N-2 environment for up to 168 h. Gravimetry was used to follow oxide growth and the oxide scale was examined with XRD. Scale morphology was investigated in detail with SEM/EDX, TEM/EDX/CBED. The alloy rapidly formed a protective two-layered alpha-alumina scale containing oxide nodules. Between the top and bottom alumina layers there was a zone containing chromia-rich particles 5-20 nm in diameter, corresponding to the original sample surface. The alumina scale mainly grew inward after 1 h of oxidation. Alumina scale growth at 900 A degrees C was initially somewhat faster in an O-2 + H2O + N-2 environment than in an O-2 + N-2 environment.
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| 43. |
- Di Falco, S., et al.
(författare)
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Estimating the Impact of Climate Change on Agriculture in Low-Income Countries: Household Level Evidence from the Nile Basin, Ethiopia
- 2012
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Ingår i: Environmental & Resource Economics. - : Springer Science and Business Media LLC. - 0924-6460 .- 1573-1502. ; 52:4, s. 457-478
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an empirical analysis of the impact of climate change on agriculture in a typical developing country. The economic implications of climate change are estimated by using both a farm productivity and a Ricardian framework. Data are drawn from about 1,000 farms producing cereal crops in the Nile Basin of Ethiopia. The thin plate spline method of spatial interpolation was used to predict household specific rainfall and temperature values using meteorological station data collected for 30 years across the regions. We found that climate change adaptation has a significant impact on both farm productivity and farm net revenues. We complement the analysis by providing an estimation of the determinants of adaptation. Extension services (both formal and farmer to farmer), as well as access to credit and information on future climate changes are key drivers of adaptation.
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| 44. |
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| 45. |
- Skedung, Lisa, et al.
(författare)
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Finger Friction Measurements on Coated and Uncoated Printing Papers
- 2010
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Ingår i: Tribology letters. - : Springer Science and Business Media LLC. - 1023-8883 .- 1573-2711. ; 37:2, s. 389-399
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Tidskriftsartikel (refereegranskat)abstract
- A macroscopic finger friction device consisting of a piezoelectric force sensor was evaluated on 21 printing papers of different paper grades and grammage. Friction between a human finger and the 21 papers was measured and showed that measurements with the device can be used to discriminate a set of similar surfaces in terms of finger friction. When comparing the friction coefficients, the papers group according to paper grade and the emerging trend is that the rougher papers have a lower friction coefficient than smoother papers. This is interpreted in terms of a larger contact area in the latter case. Furthermore, a decrease in friction coefficient is noted for all papers on repeated stroking (15 cycles back and forth with the finger). Complementary experiments indicate that both mechanical and chemical modifications of the surface are responsible for this decrease: (1) X-ray photoelectron spectroscopy measurements show that lipid material is transferred from the finger to the paper surface, (2) repeated finger friction measurements on the same paper sample reveal that only partial recovery of the frictional behaviour occurs and (3) profilometry measurements before and after stroking indicate small topographical changes associated with repeated frictional contacts.
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| 46. |
- Svensson, Teresia, 1975-, et al.
(författare)
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Is chloride a conservative ion in forest ecosystems?
- 2012
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Ingår i: Biogeochemistry. - : Springer. - 0168-2563 .- 1573-515X. ; 107:1-3, s. 125-134
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Tidskriftsartikel (refereegranskat)abstract
- Chloride (Cl-) has often been assumed to be relatively unreactive in forest ecosystems, and is frequently used as a conservative tracer to calculate fluxes of water and other ions. Recently, however, several studies have detailed cycling of Cl- in vegetation and soils. In this study Cl- budgets are compiled from 32 catchment studies to determine the extent to which Cl- is conserved in the passage through forest ecosystems. Chloride budgets from these sites vary from net retention (input/output) to net release (output/input). In the overall data set, including those sites with very high inputs of seasalt Cl-, there was a strong correspondence between inputs and outputs. However, sites with low Cl- deposition (<6 kg ha-1 year-1) consistently showed net release of Cl-, suggesting an internal source or a declining internal pool. The results indicate that Cl- may be a conservative ion in sites with high Cl- deposition, but in sites with low deposition Cl- may not be conservative. We discuss the possible causes of the Cl- imbalance and reasons why Cl- may not be conservative in ecosystem functions.
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| 47. |
- Weslien, Per, 1963, et al.
(författare)
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Carrot cropping on organic soil is a hotspot for nitrous oxide emissions
- 2012
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Ingår i: Nutrient Cycling in Agroecosystems. - : Springer Science and Business Media LLC. - 1385-1314 .- 1573-0867. ; 94:2-3, s. 249-253
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Tidskriftsartikel (refereegranskat)abstract
- The emissions of the greenhouse gas nitrous oxide (N2O) were measured from a non nitrogen fertilized carrot (Daucus carota ssp. sativa) field on an organic soil in Sweden during one cropping and post-harvest season. The cumulative emission during the measuring period of 149 days was 41 (±2.8) kg N2O ha−1. Dividing the measuring period into a cropping and a post-harvest period revealed that the presence of carrots strongly stimulated N2O emissions, as the emission during the cropping period was one order of magnitude higher compared to the post-harvest period. The N2O emission from the carrot field were higher than fluxes reported from cereal crop and grass production, but in the same order as reported fluxes from vegetable cropping on organic soils. In conclusion, our results indicate that the cultivation of root vegetable, such as carrots, on organic soil can be a high point source for N2O emissions.
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