The Experts below are selected from a list of 5481 Experts worldwide ranked by ideXlab platform
J. Tranum-jensen - One of the best experts on this subject based on the ideXlab platform.
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Specialized membrane areas in non-activated and thrombin-activated platelets.
Scandinavian Journal of Haematology, 2009Co-Authors: O. Behnke, J. Tranum-jensenAbstract:Filipin, a complex of polyene antibiotics, forms morphologically distinctive complexes with cholesterol in cell membranes under proper experimental conditions. When applied to non-activated, discoid platelets, filipin-induced lesions (FIL) occurred in rows at the platelet equator, suggesting a specialized membrane organization at the platelets' largest circumference. In some thrombin-activated platelets we observed surface membrane blebbing and release of lipid Vesicles that predominantly originated from the plasma membrane proper, but some originated from (unidentified) platelet granules. FIL were initially present in high numbers over the entire bleb, they accumulated later at the neck of blebs, while the Released Vesicle was free of FIL. Absence of intramembrane protein particles (IMP) from the membranes of blebs and Vesicles suggests that Released Vesicles are essentially without cholesterol and intrinsic membrane proteins and may consist predominantly of phospholipids. Membrane blebbing and Vesicle release may represent unmasking and release of procoagulant platelet factor 3 activity.
O. Behnke - One of the best experts on this subject based on the ideXlab platform.
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Specialized membrane areas in non-activated and thrombin-activated platelets.
Scandinavian Journal of Haematology, 2009Co-Authors: O. Behnke, J. Tranum-jensenAbstract:Filipin, a complex of polyene antibiotics, forms morphologically distinctive complexes with cholesterol in cell membranes under proper experimental conditions. When applied to non-activated, discoid platelets, filipin-induced lesions (FIL) occurred in rows at the platelet equator, suggesting a specialized membrane organization at the platelets' largest circumference. In some thrombin-activated platelets we observed surface membrane blebbing and release of lipid Vesicles that predominantly originated from the plasma membrane proper, but some originated from (unidentified) platelet granules. FIL were initially present in high numbers over the entire bleb, they accumulated later at the neck of blebs, while the Released Vesicle was free of FIL. Absence of intramembrane protein particles (IMP) from the membranes of blebs and Vesicles suggests that Released Vesicles are essentially without cholesterol and intrinsic membrane proteins and may consist predominantly of phospholipids. Membrane blebbing and Vesicle release may represent unmasking and release of procoagulant platelet factor 3 activity.
Marco Pittau - One of the best experts on this subject based on the ideXlab platform.
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proteomics and pathway analyses of the milk fat globule in sheep naturally infected by mycoplasma agalactiae provide indications of the in vivo response of the mammary epithelium to bacterial infection
Infection and Immunity, 2011Co-Authors: Maria Filippa Addis, Salvatore Pisanu, Stefania Ghisaura, Daniela Pagnozzi, Gavino Marogna, Alessandro Tanca, Grazia Biosa, Carla Cacciotto, Alberto Alberti, Marco PittauAbstract:Milk fat globules (MFGs) are Vesicles Released in milk as fat droplets surrounded by the endoplasmic reticulum and apical cell membranes. During formation and apocrine secretion by lactocytes, various amounts of cytoplasmic crescents remain trapped within the Released Vesicle, making MFGs a natural sampling mechanism of the lactating cell contents. With the aim of investigating the events occurring in the mammary epithelium during bacterial infection, the MFG proteome was characterized by two-dimensional difference gel electrophoresis (2-D DIGE), SDS-PAGE followed by shotgun liquid chromatography-tandem mass spectrometry (GeLC-MS/MS), label-free quantification by the normalized spectral abundance factor (NSAF) approach, Western blotting, and pathway analysis, using sheep naturally infected by Mycoplasma agalactiae. A number of protein classes were found to increase in MFGs upon infection, including proteins involved in inflammation and host defense, cortical cytoskeleton proteins, heat shock proteins, and proteins related to oxidative stress. Conversely, a strikingly lower abundance was observed for proteins devoted to MFG metabolism and secretion. To our knowledge, this is the first report describing proteomic changes occurring in MFGs during sheep infectious mastitis. The results presented here offer new insights into the in vivo response of mammary epithelial cells to bacterial infection and open the way to the discovery of protein biomarkers for monitoring clinical and subclinical mastitis.
Paula B Tracy - One of the best experts on this subject based on the ideXlab platform.
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Endotoxin enhances the expression of monocyte prothrombinase activity.
Blood, 1992Co-Authors: Ra Robinson, Laura A. Worfolk, Paula B TracyAbstract:Thrombin is generated on the surface of mononuclear cells (MNCs) through the assembly and function of the prothrombinase complex consisting of the enzyme factor Xa, the cofactor/factor Va, calcium ions, and an appropriate membrane surface for proper assembly of the protein constituents. Assays performed in the presence of factors Va and Xa indicated that endotoxin significantly enhanced the prothrombinase activity (1.5- to 2.5-fold; P less than .001) expressed by MNCs in a dose- and time-dependent manner. Monocytes present in the MNC suspensions were responsible for this increased activity through processes resulting in both enhanced cellular activity and the enhanced release of membranous Vesicles. Endotoxin was without effect on the expression of lymphocyte prothrombinase activity. Scanning electron microscopy techniques indicated that endotoxin resulted in extensive membrane blebbing of the monocytes present in the MNC suspensions with no effect on the morphology of the lymphocytes. Within 5 hours, endotoxin maximally enhanced the prothrombinase activity expressed by the monocyte membrane surface 2.8-fold, whereas 8 hours was required to maximally enhance the activity associated with the Released Vesicles by twofold. The observed increase in activity expressed by the monocyte membrane surface was due solely to endotoxin, since the activity expressed by the unstimulated monocyte membrane surface remained unaltered over time. In contrast, cell vesiculation, which occurred in the absence of any stimulus, was further enhanced by endotoxin. The increase in activity associated with the Released Vesicles from both stimulated and unstimulated cells paralleled an increase in the Vesicle number as determined by flow cytometric analyses. The Vesicle Released from both unstimulated and stimulated monocytes were indistinguishable in size as determined by image analysis and ranged between 0.05 and 0.3 microns in diameter. 2-Deoxy-D-glucose (2DG) significantly enhanced the prothrombinase activity expressed by the monocyte membrane surface, as well as the Released Vesicle fraction, when used alone or in addition to endotoxin. The enhanced activity associated with the Vesicle fraction again was attributed to the release of more Vesicles. In contrast, cycloheximide decreased the prothrombinase activity expressed by the monocyte membrane surface, as well as the activity associated with Vesicles Released from both stimulated and unstimulated cells. These data suggest that the expression of monocyte prothrombinase activity can be significantly enhanced by endotoxin through processes that alter the monocyte membrane surface and augment the vesiculation process. Both processes appear to be regulated by protein synthesis and adenosine triphosphate (ATP)-dependent mechanisms.
Maria Filippa Addis - One of the best experts on this subject based on the ideXlab platform.
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proteomics and pathway analyses of the milk fat globule in sheep naturally infected by mycoplasma agalactiae provide indications of the in vivo response of the mammary epithelium to bacterial infection
Infection and Immunity, 2011Co-Authors: Maria Filippa Addis, Salvatore Pisanu, Stefania Ghisaura, Daniela Pagnozzi, Gavino Marogna, Alessandro Tanca, Grazia Biosa, Carla Cacciotto, Alberto Alberti, Marco PittauAbstract:Milk fat globules (MFGs) are Vesicles Released in milk as fat droplets surrounded by the endoplasmic reticulum and apical cell membranes. During formation and apocrine secretion by lactocytes, various amounts of cytoplasmic crescents remain trapped within the Released Vesicle, making MFGs a natural sampling mechanism of the lactating cell contents. With the aim of investigating the events occurring in the mammary epithelium during bacterial infection, the MFG proteome was characterized by two-dimensional difference gel electrophoresis (2-D DIGE), SDS-PAGE followed by shotgun liquid chromatography-tandem mass spectrometry (GeLC-MS/MS), label-free quantification by the normalized spectral abundance factor (NSAF) approach, Western blotting, and pathway analysis, using sheep naturally infected by Mycoplasma agalactiae. A number of protein classes were found to increase in MFGs upon infection, including proteins involved in inflammation and host defense, cortical cytoskeleton proteins, heat shock proteins, and proteins related to oxidative stress. Conversely, a strikingly lower abundance was observed for proteins devoted to MFG metabolism and secretion. To our knowledge, this is the first report describing proteomic changes occurring in MFGs during sheep infectious mastitis. The results presented here offer new insights into the in vivo response of mammary epithelial cells to bacterial infection and open the way to the discovery of protein biomarkers for monitoring clinical and subclinical mastitis.