Search results for "Platelet"
showing 10 items of 786 documents
Inhibition of inflammatory responses by epitaondiol and other marine natural products
1995
The marine metabolites pacifenol, stypotriol triacetate and epitaondiol were tested for their effects on a number of inflammatory responses. Epitaondiol exhibited a potent topical anti-inflammatory activity related to inhibition of leukocyte accumulation. The other compounds showed a lower potency, similar to that of indomethacin. None of the compounds affected superoxide generation by human neutrophils but pacifenol effectively inhibited the degranulation response. This compound and epitaondiol decreased the release of eicosanoids with a higher potency on the cyclo-oxygenase pathway. Only epitaondiol inhibited human recombinant synovial phospholipase A2 activity in a concentration-dependen…
Activation of cGMP-dependent Protein Kinase Iβ Inhibits Interleukin 2 Release and Proliferation of T Cell Receptor-stimulated Human Peripheral T Cells
2000
Several major functions of type I cGMP-dependent protein kinase (cGK I) have been established in smooth muscle cells, platelets, endothelial cells, and cardiac myocytes. Here we demonstrate that cGK Ibeta is endogenously expressed in freshly purified human peripheral blood T lymphocytes and inhibits their proliferation and interleukin 2 release. Incubation of human T cells with the NO donor, sodium nitroprusside, or the membrane-permeant cGMP analogs PET-cGMP and 8-pCPT-cGMP, activated cGK I and produced (i) a distinct pattern of phosphorylation of vasodilator-stimulated phosphoprotein, (ii) stimulation of the mitogen-activated protein kinases ERK1/2 and p38 kinase, and, upon anti-CD3 stimu…
A peptide from the staphylococcal protein Efb binds P‐selectin and inhibits the interaction of platelets with leukocytes
2022
AimsP-selectin is a key surface adhesion molecule for the interaction of platelets with leukocytes. We have shown previously that the N-terminal domain of S. aureus extracellular fibrinogen-binding protein (Efb) binds to P-selectin and interferes with platelet-leukocyte aggregate formation. Here, we aimed to identify the minimal Efb motif required for binding platelets and to characterise its ability to interfering with the formation of platelet-leukocyte aggregates.Methods and ResultsUsing a library of synthetic peptides, we mapped the platelet-binding site to a continuous 20 amino acid stretch. The peptide Efb68-87 was able to bind to resting and, to a greater extent, thrombin-stimulated …
Influence of traditional Chinese anti-inflammatory medicinal plants on leukocyte and platelet functions.
2003
Abstract The enzymes 5-lipoxygenase and elastase are therapeutic targets in dermatological disorders such as psoriasis. Fifteen extracts from traditional Chinese medicinal plants used to treat topical inflammations were screened for their inhibitory effect on lipoxygenase, cyclooxygenase and elastase activity in intact leukocytes and platelets. Astragalus membranaceus, Forsythia suspensa and Poria cocos inhibited 5-lipoxygenase, with IC50 values of 141, 80 and 141 μg mL−1, respectively. The latter two species, along with Angelica dahurica and Angelica pubescens, also inhibited elastase (IC50 values of 80, 123, 68 and 93 μg mL−1, respectively), while A. pubescens, Atractylodes macrocephala, …
Blood flow patterns spatially associated with platelet aggregates in murine colitis.
2009
In the normal murine mucosal plexus, blood flow is generally smooth and continuous. In inflammatory conditions, such as chemically-induced murine colitis, the mucosal plexus demonstrates markedly abnormal flow patterns. The inflamed mucosal plexus is associated with widely variable blood flow velocity as well as discontinuous and even bidirectional flow. To investigate the mechanisms responsible for these blood flow patterns, we used intravital microscopic examination of blood flow within the murine mucosal plexus during dextran sodium sulphate-and trinitrobenzenesulfonic acid-induced colitis. The blood flow patterns within the mucosal plexus demonstrated flow exclusion in 18% of the vessel…
Preparation and Application of an Innovative Thrombocyte/Leukocyte-Enriched Plasma to Promote Tissue Repair in Chelonians
2015
Platelet concentrates are widely used in mammalian regenerative medicine to improve tissue healing. Chelonians (Testudines) would benefit from the application of thrombocyte preparations to regenerate damaged tissues, since traumatic injuries are leading causes of morbidity and mortality for both wild-living and domesticated animals. The aim of this study was to establish a protocol that optimized the recovery of the thrombocytes from blood samples and to show the efficacy of thrombocyte-enriched plasma in chelonians. Peripheral blood samples were obtained from Testudo spp. (n = 12) and Trachemys scripta elegans (n = 10). Blood cells were fractionated by sodium diatrizoate-sodium polysucros…
Transforming growth factors (TGF-alpha and TGF-beta1) in the determination of vitality and wound age: immunohistochemical study on human skin wounds.
2002
In continuation of former investigations on proinflammatory cytokines, in the present study the relevance of the transforming growth factors TGF-alpha and TGF-beta1 was evaluated for the diagnosis of vitality and wound age. Paraffin sections from human skin wounds due to sharp force influence, which had been collected in operations and autopsies, were investigated using immunohistochemistry. The wound age varied from a few minutes to a maximum of 6 weeks with focus on the early post-traumatic interval up to 5h. Samples from uninjured skin were available as controls. TGF-alpha (n=74) was weakly expressed in normal skin and showed a marked increase in epidermal reactivity after a wound age of…
The histone deacetylase sirtuin 2 is a new player in the regulation of platelet function
2015
SummaryBackground Histone deacetylases (HDACs) play a key role in signaling in many cell types. However, little is known about the participation of HDACs, particularly sirtuins (SIRTs), in platelet reactivity. Objective To investigate the role of HDACs in platelets, we examined the effects of SIRT inhibition on platelet function and protein acetylation in human platelets. Methods We used washed platelets obtained from healthy subjects. Cambinol (SIRT1 and SIRT2 inhibitor), AGK2 (specific SIRT2 inhibitor) and EX527 (specific SIRT1 inhibitor) were used as SIRT inhibitors. Platelets were stimulated with collagen, thrombin, or U46619, and platelet responses were determined according to optical …
Phosphorylation of CalDAG-GEFI by protein kinase A prevents Rap1b activation.
2013
Summary Background Signaling via protein kinase A (PKA) and protein kinase G (PKG) is critical for maintaining platelets in the resting state. Both kinases down-regulate the activity of the small GTPase Rap1b, a critical signaling switch for integrin activation and platelet aggregation. However, the mechanism of Rap1b regulation by PKA and PKG is largely unknown. Objective To identify the PKA phosphorylation sites in calcium and diacylglycerol-regulated guanine nucleotide exchange factor I (CalDAG-GEFI), the main GEF for Rap1b in platelets, and the effect of CalDAG-GEFI phosphorylation in Rap1b activation. Methods The phosphorylation sites in CalDAG-GEFI were identified by radio-active phos…
High-throughput elucidation of thrombus formation reveals sources of platelet function variability
2019
In combination with microspotting, whole-blood microfluidics can provide high-throughput information on multiple platelet functions in thrombus formation. Based on assessment of the inter-and intra-subject variability in parameters of microspot-based thrombus formation, we aimed to determine the platelet factors contributing to this variation. Blood samples from 94 genotyped healthy subjects were analyzed for conventional platelet phenotyping: i.e. hematologic parameters, platelet glycoprotein (GP) expression levels and activation markers (24 parameters). Furthermore, platelets were activated by ADP, CRP-XL or TRAP. Parallel samples were investigated for whole-blood thrombus formation (6 mi…