As funcões dos agregados plaquetários no rejuvenecimento da pele por meio da harmonização orofacial / The role of platelet aggregates in skin rejuvenation through orofacial harmonization

In severe COVID-19, which is characterized by blood clots and neutrophil-platelet aggregates in the circulating blood and different tissues, an increased incidence of cardiovascular complications and venous thrombotic events has been reported. The inflammatory storm that characterizes severe infections may act as a driver capable of profoundly disrupting the complex interplay between platelets, endothelium, and leukocytes, thus contributing to the definition of COVID-19-associated coagulopathy. In this frame, P-selectin represents a key molecule expressed on endothelial cells and on activated platelets, and contributes to endothelial activation, leucocyte recruitment, rolling, and tissue migration. Briefly, we describe the current state of knowledge about P-selectin involvement in COVID-19 pathogenesis, its possible use as a severity marker and as a target for host-directed therapeutic intervention.

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The role of monocytes in thrombotic disorders

Thrombosis and Haemostasis ◽

10.1160/th09-01-0023 ◽

2009 ◽

Vol 102 (11) ◽

pp. 916-924 ◽

Cited By ~ 50

Author(s):

Gregory Lip ◽

Eduard Shantsila

Keyword(s):

Innate Immunity ◽

Dendritic Cells ◽

Tissue Factor ◽

Physiological Role ◽

Coagulation Cascade ◽

Pathophysiological Role ◽

Platelet Aggregates

SummaryAlthough, the main physiological role of monocytes is attributed to innate immunity (that is, phagocytosis) and the development of tissue macrophages and dendritic cells, the pathophysiological role of these goes far behind these (simplistic) limits. Indeed, monocytes constitute a major source of blood tissue factor, a key element of the extrinsic coagulation cascade. Monocytes actively bind to platelets, thus forming very prothrombotic monocyte-platelet aggregates. Additionally, these cells link inflammation and the procoagulant state observed in various prothrombotic conditions. However, monocytes are also crucial for successful thrombus recanalisation. In this article, we review the available data on potential mechanisms that link monocytes with thrombosis-related processes.

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Haemodynamic flow conditions at the initiation of high-shear platelet aggregation: a combined in vitro and cellular in silico study

Interface Focus ◽

10.1098/rsfs.2019.0126 ◽

2020 ◽

Vol 11 (1) ◽

pp. 20190126 ◽

Cited By ~ 1

Author(s):

B. J. M. van Rooij ◽

G. Závodszky ◽

A. G. Hoekstra ◽

D. N. Ku

Keyword(s):

Platelet Aggregation ◽

In Silico ◽

Platelet Rich Plasma ◽

High Shear ◽

Shear Rates ◽

Flow Simulations ◽

In Silico Study ◽

Platelet Aggregates

The influence of the flow environment on platelet aggregation is not fully understood in high-shear thrombosis. The objective of this study is to investigate the role of a high shear rate in initial platelet aggregation. The haemodynamic conditions in a microfluidic device are studied using cell-based blood flow simulations. The results are compared with in vitro platelet aggregation experiments performed with porcine whole blood (WB) and platelet-rich-plasma (PRP). We studied whether the cell-depleted layer in combination with high shear and high platelet flux can account for the distribution of platelet aggregates. High platelet fluxes at the wall were found in silico . In WB, the platelet flux was about twice as high as in PRP. Additionally, initial platelet aggregation and occlusion were observed in vitro in the stenotic region. In PRP, the position of the occlusive thrombus was located more downstream than in WB. Furthermore, the shear rates and stresses in cell-based and continuum simulations were studied. We found that a continuum simulation is a good approximation for PRP. For WB, it cannot predict the correct values near the wall.

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The Lysis of Early Fibrin by Eosinophils

10.1055/s-0039-1680516 ◽

1977 ◽

Author(s):

Hau C. Kwaan ◽

Ali A. Hatem

Keyword(s):

Plasminogen Activator ◽

Fibrinolytic Activity ◽

Cell Membranes ◽

Red Cell ◽

Platelet Thrombus ◽

Platelet Aggregates ◽

Platelet Thrombi ◽

Arteries And Veins ◽

Morphologic Changes

This study examins the role of leukocytes within a thrombus by demonstrating the morphologic detail of their activities, the chemotactic properties of thrombi and the presence of plasminogen and possible plasminogen activator within eosinophils. A model which produces discrete, reproducible platelet thrombi in arteries and veins of dogs allowed timed studies of their early evolution. In this model, the growth of the thrombus was constantly monitored by a flowmeter and the thrombus could thus be removed at a selected period in its formation. It was then studied histologically for fibrin activity and also ultrastructually. Little fibrinolytic activity was found. In contrast to neutrophils which are concerned particularly with the phagocytosis and disruption of platelet aggregates, we observed that eosinophils participate in the lysis and disruption of the fibrin within these aggregates. The fibrin is rarely phagocytosed but is acted on at the surfaces of the eosinophils, usually in shallow invaginations of the cell membranes. The fibrin shows morphologic changes of lysis. It appears that eosinophils and neutrophils are concerned with the transformation of the early fibrin and platelet thrombus, rather than with the resolution of the formed, mainly fibrin and red cell thrombus.

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Flow studies on human GPVI-deficient blood under coagulating and noncoagulating conditions

Blood Advances ◽

10.1182/bloodadvances.2020001761 ◽

2020 ◽

Vol 4 (13) ◽

pp. 2953-2961 ◽

Cited By ~ 5

Author(s):

Magdolna Nagy ◽

Gina Perrella ◽

Amanda Dalby ◽

M. Francisca Becerra ◽

Lourdes Garcia Quintanilla ◽

...

Keyword(s):

Von Willebrand Factor ◽

Transmembrane Domain ◽

Stop Codon ◽

Premature Stop Codon ◽

Glycoprotein Vi ◽

Heterozygous Variant ◽

Platelet Aggregates ◽

Von Willebrand ◽

Willebrand Factor

Abstract The role of glycoprotein VI (GPVI) in platelets was investigated in 3 families bearing an insertion within the GP6 gene that introduces a premature stop codon prior to the transmembrane domain, leading to expression of a truncated protein in the cytoplasm devoid of the transmembrane region. Western blotting and flow cytometry of GP6hom (homozygous) platelets confirmed loss of the full protein. The level of the Fc receptor γ-chain, which associates with GPVI in the membrane, was partially reduced, but expression of other receptors and signaling proteins was not altered. Spreading of platelets on collagen and von Willebrand factor (which supports partial spreading) was abolished in GP6hom platelets, and spreading on uncoated glass was reduced. Anticoagulated whole blood flowed over immobilized collagen or a mixture of von Willebrand factor, laminin, and rhodocytin (noncollagen surface) generated stable platelet aggregates that express phosphatidylserine (PS). Both responses were blocked on the 2 surfaces in GP6hom individuals, but adhesion was not altered. Thrombin generation was partially reduced in GP6hom blood. The frequency of the GP6het (heterozygous) variant in a representative sample of the Chilean population (1212 donors) is 2.9%, indicating that there are ∼4000 GP6hom individuals in Chile. These results demonstrate that GPVI supports aggregation and PS exposure under flow on collagen and noncollagen surfaces, but not adhesion. The retention of adhesion may contribute to the mild bleeding diathesis of GP6hom patients and account for why so few of the estimated 4000 GP6hom individuals in Chile have been identified.

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The potential role of the erbium: YAG laser in skin rejuvenation†*

Aesthetic Surgery Journal ◽

10.1016/s1090-820x(98)80015-0 ◽

1998 ◽

Vol 18 (2) ◽

pp. 147-149 ◽

Cited By ~ 1

Author(s):

MRCLARK

Keyword(s):

Potential Role ◽

Skin Rejuvenation ◽

Yag Laser

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Role of the PAR4 Thrombin Receptor in Stabilizing Platelet-platelet Aggregates as Revealed by a Patient with Hermansky-Pudlak Syndrome

Thrombosis and Haemostasis ◽

10.1055/s-0037-1613071 ◽

2002 ◽

Vol 87 (04) ◽

pp. 722-727 ◽

Cited By ~ 68

Author(s):

Lidija Covic ◽

Christopher Singh ◽

Hedy Smith ◽

Athan Kuliopulos

Keyword(s):

Thrombin Receptor ◽

Aggregate Formation ◽

Dense Granules ◽

Normal Individuals ◽

Platelet Aggregate ◽

Adp Release ◽

Platelet Aggregates ◽

Adp Receptor ◽

Hermansky Pudlak Syndrome

SummaryIndividuals with Hermansky-Pudlak Syndrome (HPS) lack platelet dense granules and have no ADP-autocrine response. Despite these platelet deficiencies, HPS patients exhibit a surprisingly mild bleeding phenotype. We hypothesize that activation of the PAR4 thrombin receptor compensates for the lack of an ADP-autocrine response by the P2Y12 ADP receptor in individuals with HPS. Here, we determine that PAR4 activation by thrombin occurs well after ADP release from dense granules in normal individuals. However, the signal from PAR4 stabilizes platelet-platelet aggregate formation in the absence of P2Y12 activation by ADP. Thus, the strong signal emanating from PAR4 during platelet aggregation would provide an explanation for the mild bleeding diathesis of HPS.

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Immunothrombotic Dysregulation in COVID-19 Pneumonia Is Associated With Respiratory Failure and Coagulopathy

Circulation ◽

10.1161/circulationaha.120.048488 ◽

2020 ◽

Vol 142 (12) ◽

pp. 1176-1189 ◽

Cited By ~ 40

Author(s):

Leo Nicolai ◽

Alexander Leunig ◽

Sophia Brambs ◽

Rainer Kaiser ◽

Tobias Weinberger ◽

...

Keyword(s):

Respiratory Failure ◽

Severe Acute Respiratory Syndrome ◽

Disease Severity ◽

Severe Pneumonia ◽

Corona Virus ◽

Coagulation Tests ◽

Myocardial Involvement ◽

Platelet Aggregates ◽

Polymerase Chain

Background: Severe acute respiratory syndrome corona virus 2 infection causes severe pneumonia (coronavirus disease 2019 [COVID-19]), but the mechanisms of subsequent respiratory failure and complicating renal and myocardial involvement are poorly understood. In addition, a systemic prothrombotic phenotype has been reported in patients with COVID-19. Methods: A total of 62 subjects were included in our study (n=38 patients with reverse transcriptase polymerase chain reaction–confirmed COVID-19 and n=24 non–COVID-19 controls). We performed histopathologic assessment of autopsy cases, surface marker–based phenotyping of neutrophils and platelets, and functional assays for platelet, neutrophil functions, and coagulation tests, as well. Results: We provide evidence that organ involvement and prothrombotic features in COVID-19 are linked by immunothrombosis. We show that, in COVID-19, inflammatory microvascular thrombi are present in the lung, kidney, and heart, containing neutrophil extracellular traps associated with platelets and fibrin. Patients with COVID-19 also present with neutrophil-platelet aggregates and a distinct neutrophil and platelet activation pattern in blood, which changes with disease severity. Whereas cases of intermediate severity show an exhausted platelet and hyporeactive neutrophil phenotype, patients severely affected with COVID-19 are characterized by excessive platelet and neutrophil activation in comparison with healthy controls and non–COVID-19 pneumonia. Dysregulated immunothrombosis in severe acute respiratory syndrome corona virus 2 pneumonia is linked to both acute respiratory distress syndrome and systemic hypercoagulability. Conclusions: Taken together, our data point to immunothrombotic dysregulation as a key marker of disease severity in COVID-19. Further work is necessary to determine the role of immunothrombosis in COVID-19.

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Vigorous exercise acutely changes platelet and B-lymphocyte CD39 expression

Journal of Applied Physiology ◽

10.1152/japplphysiol.00315.2004 ◽

2005 ◽

Vol 98 (4) ◽

pp. 1414-1419 ◽

Cited By ~ 15

Author(s):

Antonino Coppola ◽

Ludovico Coppola ◽

Liliana dalla Mora ◽

Francesco M. Limongelli ◽

Antonio Grassia ◽

...

Keyword(s):

Platelet Aggregation ◽

B Lymphocytes ◽

Platelet Activation ◽

Critical Role ◽

Strenuous Exercise ◽

Platelet Glycoprotein ◽

Vigorous Exercise ◽

Platelet Aggregates

CD39/ATP diphosphohydrolase is expressed on B lymphocytes, cytotoxic T lymphocytes, monocytes, platelets, and endothelial cells, and it has a critical role in the inhibition of platelet responsiveness. To determine whether strenuous exercise could acutely change expression of CD39 in platelets and lymphocytes, eight healthy sedentary men, 34 yr old (SD 7), and eight physically active men, 34 yr old (SD 6), performed graded upright cycle ergometry to volitional exhaustion. Blood samples collected both at baseline and after exercise test were employed to measure CD39 expression in platelets and lymphocytes. The percentage of circulating platelet-platelet aggregates, the “in vitro” ADP and collagen-induced platelet aggregation, and the expression of both platelet glycoprotein IIb-IIIa (PAC-1) and P-selectin (CD62) were also considered markers of platelet activation. After strenuous exercise, all subjects demonstrated significant platelet activation as judged by the increased percentage of platelet-platelet aggregates. The in vitro ADP-induced platelet aggregation and the expression of CD62P on ADP-stimulated platelets significantly increased in sedentary but not in active subjects. After exercise, all of the subjects showed a significant reduction of CD39 expression in platelet [sedentary: from 2.2 (SD 0.8) to 1.1% (SD 0.8), P = 0.008; active: from 0.6 (SD 0.2) to 0.35% (SD 0.1), P = 0.009] and an increase of CD39 expression in B lymphocytes [sedentary: from 47 (SD 13) to 60% (SD 11), P = 0.0039; active: from 46 (SD 11) to 59% (SD 11), P = 0.0038]. Taken together, these findings confirm the critical role of this ADPase in inhibition of platelet responsiveness, also suggesting a possible role of B lymphocytes in thromboregulation mechanism.

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