HAuCl, Putative General Aquaporins Blocker, Reduces Platelet Spreading, Filopodia Formation, Procoagulant Response, and Thrombus Formation Under Flow.

: Recent studies indicate that aquaporin (AQP) water channels have a regulatory function in human platelet secretion and in procoagulant response of murine platelets. However, the engagement of AQPs in morphological changes, procoagulant response, and thrombus formation in human blood has never been investigated. : Confocal microscopy was used to study platelet spreading, filopodia formation, ballooning, and thrombus formation under flow.

Aquaporins in human platelets: intracellular localization and possible role in granule and lysosome secretion.

This study was undertaken to establish the presence and the role of aquaporins (AQPs) in human platelets. Immunodetection with polyclonal antibodies and fluorescent microscopy suggest the presence of AQP isoforms - 0-7 and 9-12 - localized (in resting platelets) in the plasma membrane and in the dense and alpha granules. In thrombin- or monensin-treated platelets, the granules' AQPs become visible in the whole cell body, indicating the granules' swelling.

Involvement of hyperglycemia in the development of platelet procoagulant response: the role of aldose reductase and platelet swelling.

: Rise in mean platelet volume (MPV) has been demonstrated to be associated with increased platelet reactivity. In diabetes patients, augmented MPV was proposed to contribute to increased risk of thrombotic complications. Therefore, the aim of this study was to investigate whether under hyperglycemic conditions, aldose reductase (AR)-mediated sorbitol formation and associated rise in cell volume, which subsequently results in platelet hyperactivation.

Reduced clot retraction rate and altered platelet energy production in patients with asthma.

Objective: Asthma enhances the risk of pulmonary embolism. The mechanism of this phenomenon is unclear.

Methods: We evaluated the kinetics of clot formation, clot retraction rate (CRR), clot volume at 40 min, the rate of lactate production (a marker of aerobic glycolysis in platelets in contracting clots), blood eosinophil count (EOS), nitric oxide in exhaled breath (FENO), and spirometry (FEV1) in 50 healthy controls and in 81 allergic asthmatics (41 subjects with steroid-naïve asthma and 40 with steroid-treated asthma).

Peroxynitrite may affect fibrinolysis via the reduction of platelet-related fibrinolysis resistance and alteration of clot structure.

We tested the hypothesis that in vitro peroxynitrite (ONOO(-), a product of activated inflammatory cells) may affect fibrinolysis in human blood through the reduction of platelet-related fibrinolysis resistance. It was found that ONOO(-) (25-300 µM) accelerated lysis of platelet-fibrin clots (in PRP) dose-dependently, whereas fibrinolysis of platelet-free clots was slightly inhibited by ≥ 1000 µM stressor. Concentrations of ONOO(-) affecting the lysis of platelet-rich clots, inhibited clot retraction (CR) in a dose-dependent manner.

Platelet-related fibrinolysis resistance in patients suffering from PV. Impact of clot retraction and isovolemic erythrocytapheresis.

Using patients with polycythemia vera (PV) as an experimental model, we evaluated the impact of clot retraction (CR) and architecture of the clot on fibrinolysis. We studied the kinetics of clot retraction and the fibrinolysis rate in whole blood from 48 PV patients and 48 healthy controls. Measurements were performed before and after isovolemic eryhrocytapheresis (ECP).

Peroxynitrite may affect clot retraction in human blood through the inhibition of platelet mitochondrial energy production.

Peroxynitrite (ONOO(-)) contributes to hemostasis abnormalities associated with inflammatory states by a poorly understood mechanism. Here we show that ONOO(-) may affect clot retraction (CR), an important step in hemostasis, by reducing contractility of human platelets resulting from the inhibition of mitochondrial energy production. Reduced CR may result in thromboembolic and hemorrhage events.

Peroxynitrite--altered platelet mitochondria--a new link between inflammation and hemostasis.

Using porcine blood, we tested the hypothesis that peroxynitrite (ONOO(-)) may affect platelet-fibrin clot formation, clot retraction rate (CRR) and fibrinolysis through the inhibition of platelet energy production. It was found that ONOO(-) reduces CRR and enlarges final clot size in platelet rich plasma (PRP) (IC(50)=100μM) and in whole blood (IC(50)=200μM) dose-dependently. In a reconstituted system (washed platelets+fibrinogen), CRR was inhibited by 5-100nM ONOO(-) (IC(50)=25nM).

Combination of LC-MS- and GC-MS-based metabolomics to study the effect of ozonated autohemotherapy on human blood.

Ozonated autohemotherapy (O3-AHT) is a medical approach during which blood obtained from the patient is ozonated and injected back into the body. Despite an increasing number of evidence that O3-AHT is safe, this type of therapy remains controversial. To extend knowledge about the changes in blood evoked by O3-AHT, LC-MS- and GC-MS-based metabolic fingerprinting was used to compare plasma samples obtained from blood before and after the treatment with potentially therapeutic concentrations of ozone.

Inflammatory markers and acid-base equilibrium in exhaled breath condensate of stable and unstable asthma patients.

Background: Nitrosative and acid stress play an important role in the pathogenesis of asthma. The aim of this study was to evaluate whether, in asthmatics, a link exists between the concentrations of nitrite/nitrate, ammonia and pH values in exhaled breath condensate (EBC) and asthma severity, lung function, exhaled nitric oxide (F(ENO)), total IgE, eosinophil cationic protein (ECP) and blood eosinophilia.

Methods: The above-mentioned parameters were measured in 19 healthy volunteers and 91 allergic asthmatics divided into three groups, i.

[Pathophysiological consequences of hemolysis. Role of cell-free hemoglobin].

Abundant hemolysis is associated with a number of inherent and acquired diseases including sickle-cell disease (SCD), polycythemia, paroxysmal nocturnal hemoglobinuria (PNH) and drug-induced hemolytic anemia. Despite different etiopathology of hemolytic diseases, many concomitant symptoms are comparable and include e.g.

Evaluation of hemostatic balance in blood from patients with polycythemia vera by means of thromboelastography: the effect of isovolemic erythrocytapheresis.

Polycythemia vera (PV) is associated with an increased frequency of thrombotic complications. This study was undertaken to evaluate the hemostatic balance in the blood of PV patients by means of thromboelastography (TEG). The effect of isovolemic erythrocytapheresis (ECP) on the hemostasis of PV patients was also studied.

[The role of interleukin 13 and interleukin 5 in asthma].

Asthma is a chronic inflammatory disorder of the airways in which many cells and cellular elements play roles. Interleukins 5 (IL-5) and 13 (IL-13) are cytokines which play important roles in the pathophysiology of asthma. Selective accumulation and activation of eosinophils in the bronchial mucosa is considered a central event in the pathogenesis of asthma.

The in vitro effect of eptifibatide, a glycoprotein IIb/IIIa antagonist, on various responses of porcine blood platelets.

The current study systematically evaluates the in vitro effect of eptifibatide, a GPIIb/IIIa blocker, on various responses of porcine platelets evoked by principal physiological stimulators. Eptifibatide at concentrations up to 40 mg/mL did not affect the calcium signal produced by thrombin, partly reduced the procoagulant response evoked by collagen, and strongly inhibited (IC50 approximately 11 mg/mL) adhesion of these cells to fibrinogen coated surfaces. Eptifibatide in a concentration-dependent manner reduced ADP, collagen, and thrombin-induced platelet aggregation (IC50 = 16-27 mg/mL), dense granule secretion (IC50 = 22-31 mg/mL) and lysosome secretion (IC50 = 25-50 mg/mL).

Vasopressin acts on platelets to generate procoagulant activity.

The aim of our study was to examine whether arginine vasopressin (AVP) is able to evoke in human platelets a procoagulant response due to activation of an Na+/H+ exchanger. It was found that treatment of platelets with AVP (20-100 nmol/l) results in generation of a weak calcium signal, activation of Na+/H+ exchanger, aggregation, and development of a procoagulant response. The AVP-evoked procoagulant response was dose and time dependent, weaker than that produced by collagen or monensin (mimics Na+/H+ exchanger), and less pronounced following the inhibition of Na+/H+ exchanger by 5-(N-ethyl-N-isopropyl) amiloride or genistein.

The in-vitro effect of tirofiban, glycoprotein IIb/IIIa antagonist, on various responses of porcine blood platelets.

The present study systematically evaluates the in-vitro effect of tirofiban, glycoprotein IIb/IIIa (integrins alphaIIbbetaIII) antagonist, on porcine blood platelets. It was found that tirofiban at concentrations up to 5,000 ng/ml did not affect the calcium signal produced by thrombin. Tirofiban, in a concentration-dependent manner reduced platelet aggregation evoked by ADP (IC50 approximately 70 ng/ml), collagen (IC50 approximately 200 ng/ml), and thrombin (IC50 approximately 5,000 ng/ml).

N-acetyl-beta-hexosaminidase activity in asthma.

Background: N-acetyl-beta-hexosaminidase (beta-hex) is a lysosomal hydrolase, which is selectively secreted into the extracellular space by inflammatory cells. The aim of our study was to assess the activity of beta-hex in the plasma of asthmatic patients, and to establish whether it correlates with asthma severity and airway inflammation.

Methods: The study was conducted in a group of 46 asthmatic patients and 13 healthy volunteers.

The involvement of Na+/K(+)-ATPase in the development of platelet procoagulant response.

In circulation, platelets may come into contact with both exogenous (cardiac glycoside treatment) and endogenously produced inhibitors of Na+/K(+)-ATPase. We examined whether blocking of platelet Na+/K(+)-ATPase by ouabain results in generation of procoagulant activity. It was shown that an in vitro treatment of platelets with ouabain (20-200 microM for 20 to 60 min) is associated with an intracellular accumulation of sodium ([Na+](i)), generation of a weak calcium signal, and expression of procoagulant activity.

Cyclosporine enhances platelet procoagulant activity.

Background: Clinical use of cyclosporine (CsA) was suggested to be associated with an increased risk of thromboembolic complications. The molecular mechanisms underlying these effects remain unresolved.

Methods: We tested the hypothesis that CsA may produce platelet procoagulant activity due to its interaction with the platelet plasma membrane.

Peroxynitrite can affect platelet responses by inhibiting energy production.

Peroxynitrite (ONOO-) strongly inhibits agonist-induced platelet responses. However, the mechanisms involved are not completely defined. Using porcine platelets, we tested the hypothesis that ONOO- reduces platelet aggregation and dense granule secretion by inhibiting energy production.

Piracetam--an old drug with novel properties?

Piracetam (2-oxo-1-pyrrolidine-acetamide), the most common of the nootropic drugs, is a cyclic derivative of gamma-aminobutyric acid. The treatment with piracetam improves learning, memory, brain metabolism, and capacity. Piracetam has been shown to alter the physical properties of the plasma membrane by increasing its fluidity and by protecting the cell against hypoxia.

The role of Na+/H+ exchanger in serotonin secretion from porcine blood platelets.

This study was undertaken to evaluate whether a link exists between the activation of protein kinase C (PKC), operation of Na(+)/H(+) exchanger (NHE), cell swelling and serotonin (5-HT) secretion in porcine platelets. Activation of platelets by thrombin or phorbol 12-myristate 13-acetate (PMA), a PKC activator, initiated a rapid rise in the activity of Na(+)/H(+) exchanger and secretion of 5-HT. Both thrombin- and PMA-evoked activation of Na(+)/H(+) exchanger was less pronounced in the presence of ethyl-isopropyl-amiloride (EIPA), an NHE inhibitor, and by GF 109203X, a PKC inhibitor.

PST 2238 as an antihypertensive compound that antagonizes the effect of endogenous cardiac glycosides.

This review examines the role of endogenous cardiac glycosides (OLF--ouabain like factors) in the pathogenesis of hypertension. The discovery of ouabain as a new adrenal hormone affecting salt and water homeostasis has initiated research on a new group of compounds. OLF may provide new insights into the mechanisms and therapy of common cardiovascular diseases.