Imaging thrombosis with 99mTc-labeled RAM.1-antibody in vivo.

Platelets play a major role in thrombo-embolic diseases, notably by forming a thrombus that can ultimately occlude a vessel. This may provoke ischemic pathologies such as myocardial infarction, stroke or peripheral artery diseases, which represent the major causes of death worldwide. The aim of this study was to evaluate the specificity of radiolabeled Rat-Anti-Mouse antibody (RAM.1).We describe a method to detect platelets by using a RAM.1 coupled with the chelating agent hydrazinonicotinic acid (HYNIC) conjugated toWe demonstrated a quick and strong affinity of the radiolabeled RAM.1 for the platelet thrombus. Results clearly demonstrated the ability of this radioimmunoconjugate for detecting thrombi from 10 min post injection with an exceptional thrombi uptake. Using FeClThanks to the high sensitivity of SPECT, we provided evidence that [journal articleresearch support, non-u.s. gov't2018 062018 03 17importe

Immobilized fibrinogen activates human platelets through GPVI

GPVI, a major platelet activation receptor for collagen and fibrin, is considered as a particularly promising safe antithrombotic target. In this study, we show that human GPVI signals upon platelet adhesion to fibrinogen. Full spreading of human platelets on fibrinogen is abolished in platelets from GPVI-deficient patients suggesting that fibrinogen activates platelets through GPVI. While mouse platelets fail to spread on fibrinogen, human-GPVI-transgenic mouse platelets show full spreading and increased Ca2+ signalling through the tyrosine kinase Syk. Direct binding of fibrinogen to human GPVI was shown by surface plasmon resonance and by increased adhesion of human GPVI-transfected Rbl-2H3 cells to fibrinogen relative to mock-transfected cells. Blockade of human GPVI with the Fab of the monoclonal antibody 9O12 impairs platelet aggregation on preformed platelet aggregates in flowing blood independent of collagen and fibrin exposure. These results demonstrate that human GPVI binds to immobilized fibrinogen and show that this contributes to platelet spreading and platelet aggregation under flow

Identification of a unique filamin A binding region within the cytoplasmic domain of glycoprotein Ibα

Binding of the platelet GPIb/V/IX (glycoprotein Ib/V/IX) receptor to von Willebrand factor is critical for platelet adhesion and aggregation under conditions of rapid blood flow. The adhesive function of GPIbα is regulated by its anchorage to the membrane skeleton through a specific interaction with filamin A. In the present study, we examined the amino acid residues within the cytoplasmic tail of GPIbα, which are critical for association with filamin A, using a series of 25-mer synthetic peptides that mimic the cytoplasmic tail sequences of wild-type and mutant forms of GPIbα. Peptide binding studies of purified human filamin A have demonstrated a major role for the conserved hydrophobic stretch L(567)FLWV(571) in mediating this interaction. Progressive alanine substitutions of triple, double and single amino acid residues within the Pro(561)–Arg(572) region suggested an important role for Trp(570) and Phe(568) in promoting GPIbα binding to filamin A. The importance of these two residues in promoting filamin A binding to GPIbα in vivo was confirmed from the study of Chinese-hamster ovary cells expressing GPIbα Trp(570)→Ala and Phe(568)→Ala substitutions. Phenotypic analysis of these cell lines in flow-based adhesion studies revealed a critical role for these residues in maintaining receptor anchorage to the membrane skeleton and in maintaining cell adhesion to a von Willebrand factor matrix under high-shear conditions. These studies demonstrate a novel filamin A binding motif in the cytoplasmic tail of GPIbα, which is critically dependent on both Trp(570) and Phe(568)

The basement membrane protein nidogen-1 supports platelet adhesion and activation

The core structure of the extracellular basement membrane is made up of self-assembling networks of collagen and laminin which associate with each other through the bridging adapter proteins including the sulfated monomeric glycoprotein nidogen. While collagen and laminin are known to support platelet adhesion and activation via β1 integrins and glycoprotein (GP) VI, respectively, whether nidogen contributes to platelet activation and hemostasis is unknown. In this study, we demonstrate that recombinant human nidogen-1 supports platelet adhesion and stimulates platelet activation in a phospholipase-C γ-2 (PLCγ2), Src and Syk kinase-dependent manner downstream. Platetet adhesion to nidogen-1 was inhibited by blocking the platelet receptors GPVI and β1 integrins. Platelet adhesion to nidogen-1 activated the IκB kinase (IKK) complex, while pharmacological inhibition of IKK blocked platelet spreading on nidogen. Taken together our results suggest that nidogen may play a redundant role in hemostasis by activating platelets downstream of GPVI

Growing winter wheat cultivars under different management intensities in France: A multicriteria assessment based on economic, energetic and environmental indicators

International audienceSince the 1970s, winter wheat management in France has focused on growing high-yielding cultivars with the intensive use of external inputs. However, over the last 10 years, breeding priorities have changed in favour of the development of cultivars with multiple resistance to fungal diseases and lodging. Low-input strategies have also been developed, to reduce costs and to meet environmental targets. In this study, we assessed the economic, energetic and environmental performances of three cultivars (C) grown under four management intensities. Two of these cultivars (Isengrain and Tremie) are both high-yielding and disease-susceptible, whereas the third (Oratorio) is multiresistant to diseases and lodging but has a lower potential yield. The four crop management systems (CM) were designed with a decrease in input level (seeds, N fertilizer, fungicides, growth regulator) from CM1 to CM4. We set up a multi-year ant multi-site network to test the C-CM pairs in a wide range of environments. The evaluation of C-CM pairs was based on a set of indicators dealing with economics (profitability, input and machinery costs per tonne), environment (pesticide use, N recovery), and energy (energy use efficiency, energy costs). As regards profitability and costs per tonne, we assessed the vulnerability of the C-CM pairs to several grain and oil price scenarios. The demonstration of synergy between the two types of innovation (multiresistant cultivars, low-input management) is a major result: each makes the other more profitable, increasing its chances of adoption in the field. The ecology-based technology package, involving the use of lower-yielding multiresistant cultivars under lower external input levels, was more profitable when grain prices were low (less than (sic)123-157 per tonne (for low and high oil prices, respectively)). By contrast, the intensive technology package, consisting of high-yielding cultivars and high levels of external inputs (N, fungicides and growth regulators), was more profitable when grain prices exceeded (sic)123-157 per tonne (for low and high oil prices, respectively). However, it was less optimal in terms of fossil energy use and potential on environmental impact. In a context of fluctuating grain and oil prices and a need to preserve resources (e.g. fossil energy, water quality), our results demonstrate the potential benefits of using low-input crop management systems. with cultivars displaying multiple resistance to diseases and lodging (Oratorio-CM3). The loss of productivity (1 t ha(-1) less than for Isengrain-CM2) due to the lower yield potential of the multiresistant cultivar and the lower levels of inputs must be seen as a necessary evil if we are to decrease the overuse of resources. There is a need to adapt current procedures for cultivar evaluation, to promote the breeding of multiresistant cultivars for low-input systems. New cultivars should be evaluated under a range of conditions, from high- to low-input systems. (C) 2011 Elsevier B.V. All rights reserved