Endothelial Damage, Neutrophil Extracellular Traps and Platelet Activation in COVID-19 vs. Community-Acquired Pneumonia: A Case-Control Study.

COVID-19 has been a diagnostic and therapeutic challenge. It has marked a paradigm shift when considering other types of pneumonia etiology. We analyzed the biomarkers related to endothelial damage and immunothrombosis in COVID-19 in comparison to community-acquired pneumonia (CAP) through a case-control study of 358 patients with pneumonia (179 hospitalized with COVID-19 vs.

Neutrophil Extracellular Traps and Platelet Activation for Identifying Severe Episodes and Clinical Trajectories in COVID-19.

The role of NETs and platelet activation in COVID-19 is scarcely known. We aimed to evaluate the role of NETs (citrullinated histone H3 [CitH3], cell-free DNA [cfDNA]) and platelet activation markers (soluble CD40 ligand [CD40L] and P-selectin) in estimating the hazard of different clinical trajectories in patients with COVID-19. We performed a prospective study of 204 patients, categorized as outpatient, hospitalized and ICU-admitted.

Neutrophil extracellular traps (NETs) in patients with STEMI. Association with percutaneous coronary intervention and antithrombotic treatments.

Background: Neutrophil extracellular traps (NETs) are formed by DNA, histones and proteolytic enzymes, and are produced by activated neutrophils through different mechanisms. In turn, NETs can activate platelets and coagulation cascade favoring thrombotic processes. The aims of this study were to analyze levels and kinetics of NETs in ST-segment elevation myocardial infarction (STEMI) patients and correlate them with antithrombotic therapy and cardiovascular outcomes at follow-up.

Neutrophil extracellular traps are increased in patients with acute ischemic stroke: prognostic significance.

Neutrophil extracellular traps (NETs) are networks of DNA, histones, and proteolytic enzymes produced by activated neutrophils through different mechanisms. NET formation is promoted by activated platelets and can in turn activate platelets, thus favoring thrombotic processes. NETs have been detected in venous and arterial thrombosis, but data in stroke are scarce.

Vasoactive properties of antihypertensive lactoferrin-derived peptides in resistance vessels: Effects in small mesenteric arteries from SHR rats.

Aims: Bovine lactoferrin (LF) hydrolysates and peptides identified thereof have shown antihypertensive effects in rat models, mainly but not exclusively by angiotensin-converting enzyme inhibition. In this study we aimed to assess the vasoactive effects and mechanisms of an ultrafiltered (<3kDa) pepsin LF hydrolysate (LFH) and a heptapeptide identified in a LF hydrolysate produced by yeast proteolysis (DPYKLRP) in peripheral resistance arteries from spontaneously hypertensive rats (SHRs).

Main Methods: We used a myograph system for isometric tension recording in isolated small mesenteric arteries from SHRs.

Regulation of Platelet Function by Acetylation/Deacetylation Mechanisms.

Reversible acetylation of histones is a well-known mechanism of epigenetic regulation of gene expression. More recently, studies have demonstrated that acetylation/deacetylation in several proteins regulate multiple aspects of cellular activity, especially those associated with energetic metabolism. Platelets are key participants in haemostasis and cardiovascular diseases.

Platelet function in malignant hematological disorders.

Purpose Of Review: In this article, we summarize the current knowledge on new roles played by platelets and their interactions with blood components, and their possible implications in malignant hematological disorders.

Recent Findings: Recent reports in the literature are revealing that platelets are important partners in different aspects of physiology and pathophysiology beyond hemostasis and thrombosis, including but not restricted to inflammation, cancer or host defense. Moreover, several studies suggest that platelet interactions with other blood cells could regulate functional and biochemical responses of each other.

Characterisation of DWI-MRI confirmed cerebral infarcts in patients with subarachnoid haemorrhage and their association with MMP-9 levels.

Objectives: It has been suggested that metalloproteinase-9 (MMP-9) could predict the onset of cerebral vasospasm after subarachnoidal haemorrhage (SAH). The aim of this study was to analyse, in patients with SAH, the difference between patients with MRI ischaemic infarcts and patients without, and to investigate the role of metalloproteases as a prognostic factor for ischaemic infarcts.

Methods: Sixty eight consecutive patients with SAH and diffusion-weighted magnetic resonance imaging (DWI-MRI) done 3 weeks after SAH.

Assessment of platelet function in acute ischemic stroke patients previously treated with aspirin.

Background: Platelet inhibition measured by platelet function tests could be critical to understand the reasons for early recurrence and to guide therapeutic recommendations. We assess the platelet function during the acute phase of ischemic stroke in patients pretreated with aspirin who continue their treatment with aspirin only, are started on clopidogrel only, or add clopidogrel to aspirin.

Methods: Sixty-four patients were taking aspirin before the stroke.

Serine/threonine phosphatases regulate platelet αIIbβ3 integrin receptor outside-in signaling mechanisms and clot retraction.

Aims: We studied the role of serine/threonine phosphatases (PSTPs) on αIIbβ3 signaling and the potential selectivity of the level of PSTP inhibition with okadaic acid (OA) on αIIbβ3 signaling for regulation of platelet aggregation and clot retraction.

Main Methods: We used washed platelets from normal donors and OA as inhibitor of PSTPs. Clot retraction was induced by 1U/mL of thrombin.

The administration of a loading dose of aspirin to patients presenting with acute myocardial infarction while receiving chronic aspirin treatment reduces thromboxane A2-dependent platelet reactivity.

Abstract The optimal dose of aspirin for patients presenting with acute myocardial infarction (AMI) while receiving chronic aspirin therapy has not been clearly established. We evaluated whether continued treatment with 100 mg of aspirin or a loading dose (200-500 mg) influences thromboxane A2 (TX) suppression or platelet reactivity. Sixty-four consecutive patients with AMI and 98 healthy subjects (82 aspirin-free and 16 receiving 100 mg daily for a week) were evaluated.

Pharmacological inhibition of platelet reactivity. Clinical and pharmacodynamic effects.

Platelets play an important role in both normal hemostasis and pathological thrombus formation. The key role of platelets in thrombosis is highlighted by the clinical benefit of treatment with antiplatelet drugs. Aspirin, either alone or in combination with clopidogrel in high-risk patients, is the most widely used antiplatelet agent.

TXA2 synthesis and COX1-independent platelet reactivity in aspirin-treated patients soon after acute cerebral stroke or transient ischaemic attack.

Introduction: The pharmacological target of aspirin is the inhibition of cyclooxygenase-1 (COX1) and thromboxane-A2 (TX) synthesis. Very few data are available on TX assessment in patients with stroke. We studied platelet TX synthesis, COX1-independent platelet reactivity, the influence of platelet-erythrocyte interactions and the potential association between platelet responses and the severity of stroke, evaluated with a clinical score (NIHSS).

Improvement of the circulatory function partially accounts for the neuroprotective action of the phytoestrogen genistein in experimental ischemic stroke.

We tested the hypothesis that the phytoestrogen genistein protects the brain against ischemic stroke by improving the circulatory function in terms of reduced production of thromboxane A2 and leukocyte-platelet aggregates, and of preserved vascular reactivity. Ischemia-reperfusion (90 min-3 days, intraluminal filament) was induced in male Wistar rats, and functional score and cerebral infarct volume were the end points examined. Genistein (10mg/kg/day) or vehicle (β-cyclodextrin) was administered at 30 min after ischemia or sham-operation.

Reduction of platelet cytosolic phospholipase A2 activity by atorvastatin and simvastatin: biochemical regulatory mechanisms.

Unlabelled: Statins have demonstrated effects beyond reducing cholesterol level that may contribute to their clinical benefit, including effects on platelet biochemistry and function.

Objectives: To explore and compare the antiplatelet effect of two lipophilic statins (atorvastatin and simvastatin) and one hydrophilic statin (pravastatin) concerning: a) collagen-induced platelet aggregation and thromboxane A2 (TXA2) synthesis; b) the additive effect of statins on TXA2 synthesis in platelets treated with a submaximally effective concentration of aspirin and c) the biochemical mechanisms involved.

Methods And Results: Washed human platelets were incubated with statins (1-20μM), and stimulated with collagen (1μg/ml) or arachidonic acid (AA) (200μM) and TXB2 was quantified by ELISA.

Influence of COX-inhibiting analgesics on the platelet function of patients with subarachnoid hemorrhage.

Background: Platelet function of patients with subarachnoid hemorrhage (SAH) may play an important part in both rebleeding and delayed cerebral ischemia, but little is known about aggregation pathways during the acute phase of stroke. Analgesics are used regularly in the first days after bleeding, and some can potentially inhibit the cyclooxygenase (COX) enzyme. We examined the platelet function of patients with SAH in order to describe their basal situation and determine whether the administration of intravenous nonsteroidal antiinflammatory drugs (NSAIDs) affected platelet aggregation.

Residual cyclooxygenase-1 activity and epinephrine reduce the antiplatelet effect of aspirin in patients with acute myocardial infarction.

Aspirin treatment is essential in patients with acute myocardial infarction (AMI) to block platelet thromboxane (TXA)₂ synthesis. Epinephrine is known to enhance platelet reactivity induced by other agonists and to be elevated in patients with AMI due to stress. Our objective was to study the influence of epinephrine on platelet TXA₂ synthesis in patients treated with aspirin for AMI at early onset (within 48 hours) and the potential biochemical mechanisms involved in the functional response.

Effect of atorvastatin on platelet thromboxane A(2) synthesis in aspirin-treated patients with acute myocardial infarction.

Inhibition of platelet thromboxane A(2) (TXA(2)) by aspirin is critical in patients with acute myocardial infarction (AMI), but some patients have persistent platelet TXA(2) production within 48 hours of the onset of AMI. Statins are known to reduce TXA(2) in aspirin-free patients with hypercholesterolemia. We hypothesized that treatment with aspirin plus atorvastatin could reduce persistent TXA(2) synthesis and aspirin resistance in patients with AMI.