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P Pignatelli

Publications and source records attributed to P Pignatelli.

At least 19 recordsLinked to original sources
PubMed2006

LDL are oxidatively modified by platelets via GP91(phox) and accumulate in human monocytes.

Oxidative stress-mediated LDL modification has a key role in initiation of the atherosclerotic process. Platelets produce reactive oxidant species (ROS) upon stimulation with agonist, but it is uncertain whether they are able to oxidatively modify LDL. Human platelets taken from healthy subjects were incubated with LDL, then stimulated with collagen. Compared with unstimulated platelets, collagen-stimulated platelets induced LDL modification as shown by enhanced conjugated dienes and lysophosphatidylcholine formation, electrophoretic mobility, Apo B-100 degradation, and monocyte LDL uptake. Activated platelets also induced a marked reduction of vitamin E contained in LDL. A significant inhibition of LDL oxidation was observed in platelets treated with arachidonyl trifluomethyl ketone (AACOCF3), an inhibitor of phospholipase A2. The experiments reported above were also conducted in patients with hereditary deficiency of gp91phox, the central core of NADPH oxidase, and in patients with hypercholesterolemia. Platelets from gp91 phox-deficient patients produced a small amount of ROS and weakly modified LDL. Conversely, platelets from hypercholesterolemic patients showed enhanced ROS formation and oxidized LDL more than platelets from healthy subjects. This study provides evidence that platelets modify LDL via NADPH oxidase-mediated oxidative stress, a phenomenon that could be dependent on arachidonic acid activation. This finding suggests a role for platelets in favoring LDL accumulation within atherosclerotic plaque.

Blood Platelets↗
PubMed2006

Enhanced soluble CD40L in patients with the metabolic syndrome: Relationship with in vivo thrombin generation.

AIMS/HYPOTHESIS: The metabolic syndrome is associated with proinflammatory and prothrombotic states. This study was designed to assess the behaviour of soluble CD40 ligand (sCD40L) and prothrombin fragment F (1+2), a marker of thrombin generation, in patients with the metabolic syndrome. METHODS: We investigated 106 patients with the metabolic syndrome, diagnosed according to the ATPIII report, and 104 subjects without the metabolic syndrome. RESULTS: Plasma values of sCD40L and F (1+2) were higher in patients with the metabolic syndrome (4.11+/-1.64 vs 2.61+/-0.89 ng/ml and 1.54+/-0.49 vs 0.87+/-0.21 nmol/l, respectively; p < 0.001) and were significantly correlated (r = 0.925, p < 0.001). Stepwise multiple linear regression analysis showed that sCD40L was significantly associated with F (1+2), female sex and waist circumference. CONCLUSIONS/INTERPRETATION: Patients with the metabolic syndrome have enhanced values of plasma sCD40L and F (1+2). The study provides further insight into the relationship between metabolic syndrome, inflammation and thrombosis.

Adult↗
PubMed2006

Polyphenols enhance platelet nitric oxide by inhibiting protein kinase C-dependent NADPH oxidase activation: effect on platelet recruitment.

Several studies demonstrated an inverse association between polyphenol intake and cardiovascular events. Platelet recruitment is an important phase of platelet activation at the site of vascular injury, but it has never been investigated whether polyphenols influence platelet recruitment. The aim of the study was to analyze in vitro whether two polyphenols, quercetin and catechin, were able to affect platelet recruitment. Platelet recruitment was reduced by NO donors and by NADPH oxidase inhibitors and was enhanced by L-NAME, an inhibitor of NO synthase. Quercetin and catechin, but not single polyphenol, significantly inhibited platelet recruitment in a concentration-dependent fashion. The formation of superoxide anion was significantly inhibited in platelets incubated with quercetin and catechin but was unaffected by a single polyphenol. Incubation of platelets with quercetin and catechin resulted in inhibition of PKC and NADPH oxidase activation. Treatment of platelets with quercetin and catechin resulted in an increase of NO and also down-regulated the expression of GpIIb/IIIa glycoprotein. This study shows that the polyphenols quercetin and catechin synergistically act in reducing platelet recruitment via inhibition of PKC-dependent NADPH oxidase activation. This effect, resulting in NO-mediated platelet glycoprotein GpIIb/IIIa down-regulation, could provide a novel mechanism through which polyphenols reduce cardiovascular disease.

Adult↗
PubMed2005

Polyphenols synergistically inhibit oxidative stress in subjects given red and white wine.

Aim of this study was to analyse the relationship between the plasma levels of polyphenols and the antioxidant activity of red and white wine. Twenty healthy subjects (HS) were randomly allocated to drink 300 ml of red (n = 10) or white n = 10 wine for 15 days. Ten HS who refrained from any alcohol beverage for 15 days were used as control. Urinary PGF-2alpha-III, a marker of oxidative stress and plasma levels of polyphenols were measured. Urinary PGF-2alpha-III significantly fell in subjects taking wine with a higher percentage decrease in subjects given red wine (-38.5 +/- 6%, p < 0.001) than in those given white wine (-23.1 +/- 6%). Subjects taking red wine had higher plasma polyphenols than those taking white wine (1.9 +/- 0.6 microM versus 1.5 +/- 0.33 microM, p < 0.001). Plasma polyphenols were inversely correlated with urinary PGF2alpha (r = 0.77, p < 0.001). No changes of urinary isoprostanes were observed in subjects who refrained from wine intake. In vitro study demonstrated that only a mixture of polyphenols, all in a range corresponding to that found in human circulation, inhibited LDL oxidation and PKC-mediated NADPH oxidase activation. Such inhibitory effects were more marked using the concentrations of polyphenols detected in human circulation after red wine intake. This study shows that red wine is more antioxidant than white wine in virtue of its higher content of polyphenols, an effect that may be dependent upon a synergism among polyphenols.

Dinoprost↗
PubMed2005

Persistent production of platelet thromboxane A2 in patients chronically treated with aspirin.

BACKGROUND: Patients treated with aspirin may have a reduced sensitivity to its antiplatelet effect. The mechanism accounting for such a reduced sensitivity might involve an impaired interaction of aspirin with cyclooxygenase-1 (COX)-1. OBJECTIVE: We sought to investigate whether platelets from patients under chronic treatment with aspirin still produce TxA2 and whether there is any relationship between the eventual persistent TxA2 formation and platelet aggregation. Finally, whether platelet-derived TxA2 can be inhibited by in vitro addition of aspirin. METHODS: Collagen-induced platelet aggregation and thromboxane-A2 (TxA2) were measured in 196 patients treated with aspirin (100-330 mg day(-1)) because of previous vascular events or presence of risk factors of atherosclerosis. RESULTS: Collagen-induced TxA2 production of the entire cohort was 128.7 +/- 21.6 pg 10(-8) cells, and was significantly correlated with platelet aggregation (Spearman's correlation coefficient = 0.44; P < 0.0001). Patients in the highest quartile of TxA2 showed higher platelet response to collagen (P < 0.0001) when compared with those in the lowest quartile. In a subgroup of 96 patients, platelets were treated in vitro with a TxA2 receptor antagonist (13-azaprostanoic acid) or aspirin before stimulation with collagen. 13-APA acid significantly inhibited platelet aggregation. Aspirin reduced (-72.9%) TxA2 production in patients with TxA2 values above the median but it was ineffective in those with TxA2 values below the median. CONCLUSION: In some patients chronically treated with aspirin platelet production of TxA2 may persist and account for enhanced platelet aggregation. Incomplete inhibition of COX-1 seems to be implicated in persistent TxA2 production.

Aged↗
PubMed2004

gp91phox-dependent expression of platelet CD40 ligand.

BACKGROUND: CD40 ligand (CD40L) expression on platelets is mediated by agonists, but the underlying mechanism is still unclear. METHODS AND RESULTS: CD40L expression was measured in platelets from healthy subjects both with and without the addition of antioxidants or a phospholipase A2 (PLA2) inhibitor and in platelets from 2 patients with an inherited deficiency of gp91phox. Immunoprecipitation analysis was also performed to determine whether normal platelets showed gp91phox expression. Unlike catalase and mannitol, superoxide dismutase inhibited agonist-induced platelet CD40L expression in healthy subjects. Immunoprecipitation analysis also showed that platelets from healthy subjects expressed gp91phox. In 2 male patients with inherited gp91phox deficiency, collagen-, thrombin-, and arachidonic acid-stimulated platelets showed an almost complete absence of superoxide anion (O(2)(-)) and CD40L expression. Incubation of platelets from healthy subjects with a PLA2 inhibitor almost completely prevented agonist-induced O(2)(-) and CD40L expression. CONCLUSIONS: These data provide the first evidence that platelet CD40L expression occurs via arachidonic acid-mediated gp91phox activation.

Adult↗
PubMed2004

Aspirin.

Explore the source record for details and available documents.

Aspirin↗
PubMed2002

Carnitine inhibits arachidonic acid turnover, platelet function, and oxidative stress.

Carnitine is a physiological cellular constituent that favors intracellular fatty acid transport, whose role on platelet function and O(2) free radicals has not been fully investigated. The aim of this study was to seek whether carnitine interferes with arachidonic acid metabolism and platelet function. Carnitine (10-50 microM) was able to dose dependently inhibit arachidonic acid incorporation into platelet phospholipids and agonist-induced arachidonic acid release. Incubation of platelets with carnitine dose dependently inhibited collagen-induced platelet aggregation, thromboxane A(2) formation, and Ca(2+) mobilization, without affecting phospholipase A(2) activation. Furthermore, carnitine inhibited platelet superoxide anion (O(2)(-)) formation elicited by arachidonic acid and collagen. To explore the underlying mechanism, arachidonic acid-stimulated platelets were incubated with NADPH. This study showed an enhanced platelet O(2)(-) formation, suggesting a role for NADPH oxidase in arachidonic acid-mediated platelet O(2)(-) production. Incubation of platelets with carnitine significantly reduced arachidonic acid-mediated NADPH oxidase activation. Moreover, the activation of protein kinase C was inhibited by 50 microM carnitine. This study shows that carnitine inhibits arachidonic acid accumulation into platelet phospholipids and in turn platelet function and arachidonic acid release elicited by platelet agonists.

Arachidonic Acid↗
PubMed2002

Involvement of GD3 in platelet activation. A novel association with Fcgamma receptor.

Gangliosides are sialic acid-containing glycosphingolipids present in the outer leaflet of the plasma membrane of many cell types where they modulate adhesive processes. The main population of glycolipids in resting platelets is represented by ganglioside M3 (GM3). It has been demonstrated that following platelet activation ganglioside D3 (GD3) is rapidly formed from the GM3 pool. The present study was designed to evaluate the link between platelet activation and GD3 expression and to verify whether this ganglioside might play a role in modulating signal transduction events. Our results suggest that following platelet activation, GD3 is rapidly expressed on the platelet surface and internalised to the cytoskeleton where it transiently associates first with the Src family tyrosine kinase Lyn then with the Fc receptor gamma chain. This sequence of events ultimately leads to an enhanced CD32 (the Fc receptor isoform present in platelets) expression on the platelet membrane. These data drive us to speculate that GD3 might act as second messenger in the activatory cascade, which leads to CD32 expression and triggers platelet adhesion and spreading to the subendothelial matrix.

Adenosine Diphosphate↗
PubMed2001

Involvement of the glycoproteic Ib-V-IX complex in nickel-induced platelet activation.

We studied the effect of nickel ions on platelet function because hypernickelemia has been found in patients with acute myocardial infarction. We previously demonstrated that nickel can activate an intracellular pathway leading to cytoskeleton reorganization consequent to tyrosine phosphorylation of p60(src) in human platelets independently of integrin alpha-IIb-beta(3). Moreover, in von Willebrand factor-stimulated platelets, the tyrosine phosphorylation of pp60(c-src) is closely associated with the activation of phosphatidylinositol 3-kinase (PIK), and two adhesion receptors, glycoprotein (Gp)Ib and GpIIb/IIIa(alpha-IIb-beta(3)), are involved. In our study, 1 and 5 mM nickel in the presence of fibrinogen induced platelet aggregation (independently of protein kinase C activation) and secretion. The pretreatment with a PIK inhibitor, wortmannin, strongly decreased nickel-induced platelet aggregation. Platelet treatment with mocarhagin, a cobra venom metalloproteinase that cleaves GpIba, significantly reduced aggregation induced by 5 mM without affecting the response to other agonists such as adenosine diphosphate (ADP). Moreover, nickel caused PIK translocation to the cytoskeleton. Taken together, these observations suggest a partial involvement of both integrins alpha-IIb-beta(3) and GpIb-V-IX complex in Ni(2+)-induced platelet activation.

Cytoskeleton↗
PubMed2000

The flavonoids quercetin and catechin synergistically inhibit platelet function by antagonizing the intracellular production of hydrogen peroxide.

BACKGROUND: Epidemiologic studies have shown an inverse relation between moderate consumption of red wine and cardiovascular disease. Studies have shown that red wine and its component flavonoids inhibit in vivo platelet activation, but the underlying mechanism has not yet been identified. OBJECTIVE: Because we showed previously that collagen-induced platelet aggregation is associated with a burst of hydrogen peroxide, which in turn contributes to stimulating the phospholipase C pathway, the aim of this study was to investigate whether flavonoids synergize in inhibiting platelet function and interfere with platelet function by virtue of their antioxidant effect. DESIGN: We tested the effect of 2 flavonoids, quercetin and catechin, on collagen-induced platelet aggregation and hydrogen peroxide and on platelet adhesion to collagen. RESULTS: Catechin (50-100 micromol/L) and quercetin (10-20 micromol/L) inhibited collagen-induced platelet aggregation and platelet adhesion to collagen. The combination of 25 micromol catechin/L and 5 micromol quercetin/L, neither of which had any effect on platelet function when used alone, significantly inhibited collagen-induced platelet aggregation and platelet adhesion to collagen. Such a combination strongly inhibited collagen-induced hydrogen peroxide production, calcium mobilization, and 1,3,4-inositol triphosphate formation. CONCLUSIONS: These data indicate that flavonoids inhibit platelet function by blunting hydrogen peroxide production and, in turn, phospholipase C activation and suggest that the synergism among flavonoids could contribute to an understanding of the relation between the moderate consumption of red wine and the decreased risk of cardiovascular disease.

Blood Platelets↗
PubMed2000

Superoxide anion and hydroxyl radical release by collagen-induced platelet aggregation--role of arachidonic acid metabolism.

Previous study demonstrated that platelets undergoing anoxia-reoxygenation generate superoxide anion (O2-) and hydroxyl radical (OH ) which in turn contribute to activate arachidonic acid (AA) metabolism. However it has not been clarified if oxygen free radicals (OFRs) are also generated when platelets are aggregated by common agonists. We used two probes, i.e. lucigenin and salicylic acid (SA), to measure platelet release of O2- and OH(0), respectively. Among the agonists used, such as ADP, thrombin and collagen, the release of O2- and OH was observed mainly when platelets were stimulated with collagen. Such release was inhibited in platelets pre-treated by aspirin suggesting that AA metabolism was the main source of O2- and OH(0) formation. To further analyze this relationship, O2- and OH(0) formation was measured during AA-stimulated platelet aggregation (PA); we observed that O2- and OH(0) release were dependent upon AA concentration. Furthermore, we found that the incubation of platelets with AACOCF3, a potent inhibitor of cytosolic phospholipase A2, inhibited collagen-induced platelet O2- and OH(0) release. The incubation of platelets with salicylic acid or ascorbic acid, which blunt OH and O2- respectively, inhibited both collagen-induced platelet aggregation and AA-release. This study demonstrated that collagen-induced platelet aggregation is associated with O2- and OH formation, which is dependent upon AA release and metabolism.

Adenosine Diphosphate↗
PubMed1999

Concomitant activation of Gi protein-coupled receptor and protein kinase C or phospholipase C is required for platelet aggregation.

It has recently been suggested that the concomitant activation of two distinct G protein-coupled receptors (G(i) and G(q)) is essential for platelet aggregation: in fact, the thromboxane A2 synthetic agonist, U46619, which causes the selective activation of Gq, is not able to elicit fibrinogen receptor exposure unless ADP or epinephrine is present. In the present study we demonstrate that a direct Gq activation is not required for platelet aggregation and that the activation of an enzyme downstream of Gq, such as phospholipase C (PLC) or protein-kinase C (PKC), is sufficient for such a process. In fact, platelet aggregation occurred in response to the snake venom toxin convulxin, which activates the PLC isoform PLCgamma2 or to cytosolic PKC activator phorbol 12-myristate 13-acetate (PMA) provided a Gi protein-coupled receptor was activated by ADP or epinephrine. The evidence that the PKC inhibitor, Ro 31-8220 did not suppress platelet aggregation in response to convulxin plus ADP or epinephrine led us to conclude that PLC and PKC are both involved in platelet aggregation, although not concomitantly, provided a Gi protein-coupled receptor is activated.

Adenosine Diphosphate↗
PubMed1999

Another set of responses and correlated responses to selection on age at reproduction in Drosophila melanogaster.

Ageing is the decline in survival probability and fertility later in adult life. It can evolve through mutation accumulation and pleiotropy. Artificial selection by age at reproduction is a useful method for detecting the effects of pleiotropy, and for producing lines that differ in their rate of ageing for further analysis. However, the approach has encountered difficulties from gene-environment interaction and inadvertent selection. We have produced a new set of selection lines in Drosophila melanogaster, breeding from either 'young' or 'old' adults, and avoiding some of the difficulties present in previous studies. Breeding from older adults resulted in an evolutionary increase in survival but, contrary to all previous studies using this method, in no increase in late-life fertility. The increase in survival was accompanied by an evolutionary decline in fertility early in adult life, confirming the importance of pleiotropy in the evolution of ageing. Contrary to previous studies, there were no correlated responses to selection in the pre-adult period; development time, larval competitive ability and adult size achieved did not differ between the lines from the two selection regimes.

Aging↗