Search results for "Platelet"

Change in Protein Phenotype without a Nucleus: Translational Control in Platelets

2004

For most cells the nucleus takes center stage. Not only is it the largest organelle in eukaryotic cells, it carries most of the genome and transcription of DNA to RNA largely takes place in the nucleus. Because transcription is a major step in gene regulation, the absence of a nucleus is limiting from a biosynthetic standpoint. Consequently, the anucleate status of platelets has stereotyped it as a cell without synthetic potential. It is now clear, however, that this viewpoint is far too simplistic. In response to physiologic stimuli, platelets synthesize biologically relevant proteins that are regulated via gene expression programs at the translational level. This process does not require …

Vitamin C blocks inflammatory platelet-activating factor mimetics created by cigarette smoking.

1997

Cigarette smoking within minutes induces leukocyte adhesion to the vascular wall and formation of intravascular leukocyte-platelet aggregates. We find this is inhibited by platelet-activating factor (PAF) receptor antagonists, and correlates with the accumulation of PAF-like mediators in the blood of cigarette smoke-exposed hamsters. These mediators were PAF-like lipids, formed by nonenzymatic oxidative modification of existing phospholipids, that were distinct from biosynthetic PAF. These PAF-like lipids induced isolated human monocytes and platelets to aggregate, which greatly increased their secretion of IL-8 and macrophage inflammatory protein-1alpha. Both events were blocked by a PAF r…

Eltrombopag in chronic hepatitis C

2014

Chronic hepatitis C is a public health problem worldwide. Unfortunately, not all patients may benefit from antiviral therapy due to thrombocytopenia. Its causes are represented by portal hypertension and platelet sequestration in the spleen, decreased serum levels or activity of thrombopoietin, the bone marrow suppression induced by hepatitis C virus and a possible adverse effect of interferon. Thrombopoietin receptor analogs may contribute to increase platelet counts in these patients. Eltrombopag binds to another region of the thrombopoietin receptor compared to endogenous thrombopoietin and stimulates the proliferation and maturation of megakaryocytes and the platelet production in a dos…

Anti-metastatic activity of heparin is probably associated with modulation of SDF-1-CXCR4 axis

2006

Buffy coat-derived platelets cryopreserved using a new method: Results from in vitro studies

2018

Abstract Cryopreservation for the long-term storage of platelets (PLTs) is a useful method to overcome the limits of platelet shortage. This is an in vitro prospective study to evaluate the count, viability, and function of buffy coat-derived pooled platelet concentrates (BC-PLTs), treated with dimethyl sulphoxide (DMSO) and cryopreserved (CRY BC-PLTs) at −80 °C with a modified Valeri method. PLTs were stored in 6% DMSO with a patented kit. Overall, 49 BC-PLTs from 245 healthy volunteer donors were prepared, cryopreserved, and analysed before and after 3, 6, and 9 months of storage. In flow cytometry, a statistically significant reduction in CD 42b (92.7 ± 4.29% at T0 vs. 23.6 ± 27.5% at T3…

Comparative study on biological effects of the guinea pig complement-peptide C3a and C3a-related synthetic oligopeptides

1980

Dose-response experiments with guinea pig C3a and a synthetic hexapeptide (amino acid residues 72–77), representing the COOH-terminal sequence of human C3a, were performed in two recently described bioassay systems for C3a, i.e. cytotoxicity against tumor cells measured as LDH and 51Cr-release and non cytolytic serotonin release from guinea pig platelets. Compared to the classical anaphylatoxic assay (guinea pig ileum contraction), nearly identical reactivities were observed in all three test systems with C3a and, although quantitatively different, with hexapeptide.

Differences in non-MHC restricted cytotoxic activities of human peripheral blood lymphocytes after transfusion with allogeneic leukocytes or platelet…

1990

Abstract MHC-unrestricted cytotoxic activity of peripheral blood lymphocytes (PBL) from 4–6 healthy donors was investigated before and after transfusion with allogeneic leukocytes or platelets. Natural killer and lectin-dependent cellular cytotoxicity (LDCC) of PBL was tested against K562 and Raji target cells in a 4-h and 16-h 51 Cr-release assay, respectively. After allotransfusion with leukocytes, we found increased cytotoxic activity of each donor's PBL against all the three targets on day 3 or 7. The highest non-specific cytotoxic activity was detected against the relatively NK resistant Raji target cells. The increase of cytotoxic activity was lowest against the LDCC target (PHA-treat…

Haemostasis in chronic kidney disease

2013

The coagulation system has gained much interest again as new anticoagulatory substances have been introduced into clinical practice. Especially patients with renal failure are likely candidates for such a therapy as they often experience significant comorbidity including cardiovascular diseases that require anticoagulation. Patients with renal failure on new anticoagulants have experienced excessive bleeding which can be related to a changed pharmacokinetic profile of the compounds. However, the coagulation system itself, even without any interference with coagulation modifying drugs, is already profoundly changed during renal failure. Coagulation disorders with either episodes of severe bl…

Time-resolved characterization of cAMP/PKA-dependent signaling reveals that platelet inhibition is a concerted process involving multiple signaling p…

2014

One of the most important physiological platelet inhibitors is endothelium-derived prostacyclin which stimulates the platelet cyclic adenosine monophosphate/protein kinase A (cAMP/PKA)-signaling cascade and inhibits virtually all platelet-activating key mechanisms. Using quantitative mass spectrometry, we analyzed time-resolved phosphorylation patterns in human platelets after treatment with iloprost, a stable prostacyclin analog, for 0, 10, 30, and 60 seconds to characterize key mediators of platelet inhibition and activation in 3 independent biological replicates. We quantified over 2700 different phosphorylated peptides of which 360 were significantly regulated upon stimulation. This com…

The evolving role of platelets in inflammation.

2003

Platelets are small in size and simple in structure. Nevertheless, these anucleate cytoplasts utilize complex molecular systems to regulate a variety of biological functions. Here we review evolutionary paths, traditional roles, and previously unrecognized biological capacities of platelets that interface thrombosis with inflammation and potentially identify new roles in inflammatory diseases.