In vivo interaction of pulmonary intravascular macrophages with activated platelets in microvessels of equine lung after multiple exposures to halothane, isoflurane, and thiamylal: A comparative ultrastructural and cytochemical study

The PIM of sheep, calf, goat and horse has a characteristic ultrastructural feature in the form of a unique, heparin sensitive, globular surface coat present around the plasma membrane with an intervening electron lucent space of 32-40 nm. We previously showed the active involvement of this surface coat in the phagocytosis of tracer material like monastral blue and cationized ferritin. The surface coat is capable of reconstitution in vivo following disruption with heparin. The present study was aimed to investigate whether PIM is the source of surface coat or not. In the recent years the BFA has been extensively used to understand the secretory pathways in the cells because of its ability to cause a rapid and reversible block to the anterograde transport of proteins from the endoplasmic reticulum to the Golgi.Sheep (n=6) were weighed, their plasma volume was calculated indirectly and based on which a sufficient single intravenous dose of BFA was given so as to reach a concentration of 4-5 microgram/ml of plasma.

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In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100083035 ◽

1978 ◽

Vol 36 (2) ◽

pp. 434-435

Author(s):

D. Reis ◽

B. Vian ◽

J. C. Roland

Keyword(s):

Cell Wall ◽

Self Assembly ◽

Plant Cell Wall ◽

Higher Plants ◽

Three Dimensional ◽

Cytochemical Study ◽

Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

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Mitochondrial matrix calcium ions regulate energy production in myocardium: A cytochemical study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134429 ◽

1990 ◽

Vol 48 (2) ◽

pp. 166-167

Author(s):

W.A. Jacob ◽

R. Hertsens ◽

A. Van Bogaert ◽

M. De Smet

Keyword(s):

Energy Metabolism ◽

Calcium Ions ◽

Energy Production ◽

Regulation Of Respiration ◽

Free Calcium ◽

Mitochondrial Matrix ◽

Cytochemical Study ◽

Nmr Techniques

In the past most studies of the control of energy metabolism focus on the role of the phosphorylation potential ATP/ADP.Pi on the regulation of respiration. Studies using NMR techniques have demonstrated that the concentrations of these compounds for oxidation phosphorylation do not change appreciably throughout the cardiac cycle and during increases in cardiac work. Hence regulation of energy production by calcium ions, present in the mitochondrial matrix, has been the object of a number of recent studies.Three exclusively intramitochondnal dehydrogenases are key enzymes for the regulation of oxidative metabolism. They are activated by calcium ions in the low micromolar range. Since, however, earlier estimates of the intramitochondnal calcium, based on equilibrium thermodynamic considerations, were in the millimolar range, a physiological correlation was not evident. The introduction of calcium-sensitive probes fura-2 and indo-1 made monitoring of free calcium during changing energy metabolism possible. These studies were performed on isolated mitochondria and extrapolation to the in vivo situation is more or less speculative.

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Anti-β2 Glycoprotein I Antibodies Cause Inflammation and Recruit Dendritic Cells in Platelet Clearance

Thrombosis and Haemostasis ◽

10.1055/s-0037-1616059 ◽

2001 ◽

Vol 86 (11) ◽

pp. 1257-1263 ◽

Cited By ~ 6

Author(s):

Attilio Bondanza ◽

Angelo Manfredi ◽

Valérie Zimmermann ◽

Matteo Iannacone ◽

Angela Tincani ◽

...

Keyword(s):

Dendritic Cells ◽

Inflammatory Responses ◽

Glycoprotein I ◽

Activated Platelets ◽

Tnf Α ◽

Per Se ◽

Antigen Presenting ◽

Antiinflammatory Cytokine

SummaryScavenger phagocytes are mostly responsible for the in vivo clearance of activated or senescent platelets. In contrast to other particulate substrates, the phagocytosis of platelets does not incite pro-inflammatory responses in vivo. This study assessed the contribution of macrophages and dendritic cells (DCs) to the clearance of activated platelets. Furthermore, we verified whether antibodies against the β2 Glycoprotein I (β2GPI), which bind to activated platelets, influence the phenomenon. DCs did not per se internalise activated platelets. In contrast, macrophages efficiently phagocytosed platelets. In agreement with the uneventful nature of the clearance of platelets in vivo, phagocytosing macrophages did not release IL-1β, TNF-α or IL-10. β2GPI bound to activated platelets and was required for their recognition by anti-ββ2GPI antibodies. DCs internalised platelets opsonised by anti-ββ2GPI antibodies. The phagocytosis of opsonised platelets determined the release of TNF-α and IL-1β by DCs and macrophages. Phagocytosing macrophages, but not DCs, secreted the antiinflammatory cytokine IL-1β0. We conclude that anti-ββ2GPI antibodies cause inflammation during platelet clearance and shuttle platelet antigens to antigen presenting DCs.

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A Comparison of the Effect of Decorsin and Two Disintegrins, Albolabrin and Eristostatin, on Platelet Function

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649933 ◽

1995 ◽

Vol 74 (05) ◽

pp. 1316-1322 ◽

Cited By ~ 13

Author(s):

Mary Ann McLane ◽

Jagadeesh Gabbeta ◽

A Koneti Rao ◽

Lucia Beviglia ◽

Robert A Lazarus ◽

...

Keyword(s):

Platelet Aggregation ◽

Platelet Function ◽

Sequence Similarity ◽

Platelet Aggregation Inhibitors ◽

Antiplatelet Drug ◽

Rgd Sequence ◽

Fibrinogen Receptor ◽

Activated Platelets

SummaryNaturally-occurring fibrinogen receptor antagonists and platelet aggregation inhibitors that are found in snake venom (disintegrins) and leeches share many common features, including an RGD sequence, high cysteine content, and low molecular weight. There are, however, significant selectivity and potency differences. We compared the effect of three proteins on platelet function: albolabrin, a 7.5 kDa disintegrin, eristostatin, a 5.4 kDa disintegrin in which part of the disintegrin domain is deleted, and decorsin, a 4.5 kDa non-disintegrin derived from the leech Macrobdella decora, which has very little sequence similarity with either disintegrin. Decorsin was about two times less potent than albolabrin and six times less potent than eristostatin in inhibiting ADP- induced human platelet aggregation. It had a different pattern of interaction with glycoprotein IIb/IIIa as compared to the two disintegrins. Decorsin bound with a low affinity to resting platelets (409 nM) and to ADP-activated platelets (270 nM), and with high affinity to thrombin- activated platelets (74 nM). At concentrations up to 685 nM, it did not cause expression of a ligand-induced binding site epitope on the (β3 subunit of the GPIIb/IIIa complex. It did not significantly inhibit isolated GPIIb/IIIa binding to immobilized von Willebrand Factor. At low doses (1.5-3.0 μg/mouse), decorsin protected mice against death from pulmonary thromboembolism, showing an effect similar to eristostatin. This suggested that decorsin is a much more potent inhibitor of platelet aggregation in vivo than in vitro, and it may have potential as an antiplatelet drug.

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A P-Selectin/CD62P Monoclonal Antibody (LYP-20), in Tandem with Flow Cytometry, Detects in vivo Activated Circulating Rat Platelets in Severe Vascular Trauma

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648952 ◽

1994 ◽

Vol 72 (05) ◽

pp. 745-749 ◽

Cited By ~ 7

Author(s):

Elza Chignier ◽

Maud Parise ◽

Lilian McGregor ◽

Caroline Delabre ◽

Sylvie Faucompret ◽

...

Keyword(s):

Monoclonal Antibody ◽

Flow Cytometry ◽

Platelet Activation ◽

Peripheral Blood ◽

Vascular Trauma ◽

Activated Platelets ◽

Group I ◽

Group Ii ◽

Rat Platelets

SummaryP-selectin, also known as CD62P, GMP140 or PADGEM, is present in platelet a-granules and endothelial cell Weibel-Palade bodies and is very rapidly expressed on the surface of these cells on activation. In this study, an anti P-selectin monoclonal antibody (LYP20) was used, in tandem with flow cytometry, to identify activated platelets at the site of induced vascular trauma or in peripheral blood. Moreover, electron microscopy was performed to characterize sites of vascular trauma and quantify the number of adhering platelets. The same induced vascular trauma was observed to result into animals responding in 2 different ways (Group I, Group II) following the degree of platelet activation. Five rats, out of 14 with induced vascular trauma, had more than half of their circulating platelets expressing P-selectin when drawn at the site of the trauma (67.4% ± 3.44) or in peripheral blood (78.5% ± 2.5) (Group I). In the remaining 9 animals a much smaller proportion of circulating platelets expressed P-selectin when assayed from trauma sites (18% ± 3.34) or in peripheral blood (18.0% ± 4.30) (Group II). Enhanced P-selectin expression by circulating platelets in Group I, compared to Group II, appears to be linked to the degree of activated platelets adhering at sites of trauma (171 ± 15 × 103 platelets versus 48 ± 31 × 103 platelets per mm2). In the 5 control animals, that were not operated on, platelets expressing P-selectin when drawn at the site of a mock trauma (7.0% ± 1.84) or in the peripheral blood (11.2% ± 3.30) showed little activation. In addition, no platelet adhesion was seen on the vascular bed of these animals. Results from this study show that analysis of P-selectin (CD62P) expression, in circulating platelets, is a valuable and rapid marker of platelet activation following severe vascular trauma induced in rats. However, activated platelets were not detected to the same extent in the peripheral blood of all animals having undergone vascular trauma. It is conceivable that platelets, depending on the degree of activation, may be actively sequestered in organs and prevented from circulating. Alternatively, P-selectin may be rapidly endocytosed, or not expressed, by activated circulating platelets depending on the type of agonists implicated in vivo activation.

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Accumulation of Tissue Factor into Developing Thrombi In Vivo Is Dependent upon Microparticle P-Selectin Glycoprotein Ligand 1 and Platelet P-Selectin

Journal of Experimental Medicine ◽

10.1084/jem.20021868 ◽

2003 ◽

Vol 197 (11) ◽

pp. 1585-1598 ◽

Cited By ~ 501

Author(s):

Shahrokh Falati ◽

Qingde Liu ◽

Peter Gross ◽

Glenn Merrill-Skoloff ◽

Janet Chou ◽

...

Keyword(s):

Tissue Factor ◽

Blood Coagulation ◽

Thrombus Formation ◽

Recipient Mouse ◽

Wild Type ◽

Activated Platelets ◽

Injury Model ◽

Platelet Thrombus ◽

Flowing Blood

Using a laser-induced endothelial injury model, we examined thrombus formation in the microcirculation of wild-type and genetically altered mice by real-time in vivo microscopy to analyze this complex physiologic process in a system that includes the vessel wall, the presence of flowing blood, and the absence of anticoagulants. We observe P-selectin expression, tissue factor accumulation, and fibrin generation after platelet localization in the developing thrombus in arterioles of wild-type mice. However, mice lacking P-selectin glycoprotein ligand 1 (PSGL-1) or P-selectin, or wild-type mice infused with blocking P-selectin antibodies, developed platelet thrombi containing minimal tissue factor and fibrin. To explore the delivery of tissue factor into a developing thrombus, we identified monocyte-derived microparticles in human platelet–poor plasma that express tissue factor, PSGL-1, and CD14. Fluorescently labeled mouse microparticles infused into a recipient mouse localized within the developing thrombus, indicating that one pathway for the initiation of blood coagulation in vivo involves the accumulation of tissue factor– and PSGL-1–containing microparticles in the platelet thrombus expressing P-selectin. These monocyte-derived microparticles bind to activated platelets in an interaction mediated by platelet P-selectin and microparticle PSGL-1. We propose that PSGL-1 plays a role in blood coagulation in addition to its known role in leukocyte trafficking.

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Activated platelets induce Weibel-Palade–body secretion and leukocyte rolling in vivo: role of P-selectin

Blood ◽

10.1182/blood-2005-04-1530 ◽

2005 ◽

Vol 106 (7) ◽

pp. 2334-2339 ◽

Cited By ~ 124

Author(s):

Vandana S. Dole ◽

Wolfgang Bergmeier ◽

Heather A. Mitchell ◽

Sarah C. Eichenberger ◽

Denisa D. Wagner

Keyword(s):

Acute Inflammation ◽

Endothelial Activation ◽

Leukocyte Rolling ◽

Activated Platelets ◽

Baseline Levels ◽

Von Willebrand ◽

Willebrand Factor ◽

Body Secretion

AbstractThe presence of activated platelets and platelet-leukocyte aggregates in the circulation accompanies major surgical procedures and occurs in several chronic diseases. Recent findings that activated platelets contribute to the inflammatory disease atherosclerosis made us address the question whether activated platelets stimulate normal healthy endothelium. Infusion of activated platelets into young mice led to the formation of transient platelet-leukocyte aggregates and resulted in a several-fold systemic increase in leukocyte rolling 2 to 4 hours after infusion. Rolling returned to baseline levels 7 hours after infusion. Infusion of activated P-selectin-/- platelets did not induce leukocyte rolling, indicating that platelet P-selectin was involved in the endothelial activation. The endothelial activation did not require platelet CD40L. Leukocyte rolling was mediated solely by the interaction of endothelial P-selectin and leukocyte P-selectin glycoprotein ligand 1 (PSGL-1). Endothelial P-selectin is stored with von Willebrand factor (VWF) in Weibel-Palade bodies. The release of Weibel-Palade bodies on infusion of activated platelets was indicated by both elevation of plasma VWF levels and by an increase in the in vivo staining of endothelial P-selectin. We conclude that the presence of activated platelets in circulation promotes acute inflammation by stimulating secretion of Weibel-Palade bodies and P-selectin–mediated leukocyte rolling.

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Abstract 049: Novel Tirofiban Conjugate for the in vivo Detection of Activated Platelets

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.38.suppl_1.049 ◽

2018 ◽

Vol 38 (Suppl_1) ◽

Author(s):

Khanh Q Ha ◽

Xiaoxin Zheng ◽

Chase Kessinger ◽

Farouc Jaffer ◽

Jason McCarthy

Keyword(s):

Activated Platelets ◽

In Vivo Detection

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PSGL-1 regulates platelet P-selectin-mediated endothelial activation and shedding of P-selectin from activated platelets

Thrombosis and Haemostasis ◽

10.1160/th07-03-0207 ◽

2007 ◽

Vol 98 (10) ◽

pp. 806-812 ◽

Cited By ~ 46

Author(s):

Vandana Dole ◽

Wolfgang Bergmeier ◽

Ian Patten ◽

Junichi Hirahashi ◽

Tanya Mayadas ◽

...

Keyword(s):

Endothelial Activation ◽

Leukocyte Rolling ◽

Wild Type ◽

Platelet Surface ◽

Activated Platelets ◽

And Function ◽

Body Secretion

SummaryWe have previously shown that activated platelets in circulation stimulate release of endothelial Weibel-Palade bodies thus increasing leukocyte rolling in venules. P-selectin on the activated platelets mediates adhesion to leukocytes via PSGL-1 and is rapidly shed into plasma. We were interested in studying the role of PSGL-1 in regulating expression and function of platelet P-selectin. We show here that PSGL-1 is critical for the activation of endothelial cells in venules of mice infused with activated platelets. The interaction of platelet P-selectin with PSGL-1 is also required for P-selectin shedding, as P-selectin was retained significantly longer on the surface of activated platelets infused into PSGL-1-/- compared to wild-type mice. The leukocyte integrin αMβ2 (Mac-1) was not required for P-selectin shedding. In addition to shedding, P-selectin can be downregulated from the platelet surface through internalization and this is the predominant mechanism in the absence of PSGL-1. We demonstrate that leukocyte- neutrophil elastase,known to cleave P-selectin in vitro, is not the major sheddase for P-selectin in vivo. In conclusion, interaction of platelet P-selectin with PSGL-1 is crucial for activation of the endothelium andWeibel-Palade body secretion. The interaction with PSGL-1 also results in rapid shedding of P-selectin thus downregulating the inflammatory potential of the platelet.

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