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Biomedical subjects

G de Gaetano

Publications and source records attributed to G de Gaetano.

At least 37 records · Page 2Linked to original sources
PubMed2001

Wine and cardiovascular disease.

The objective of the European project FAIR CT 97 3261 "Wine & Cardiovascular Disease" was to have insight into the biological effects and mechanisms of wine constituents as protective factors against cardiovascular disease and to evaluate their clinical relevance in the context of a regular and moderate wine consumption (1, 2). The project aimed at evaluating the effects of red wine polyphenolic extracts (RWPE) on the major components contributing to the pathophysiology of atherosclerosis and thrombosis, namely vascular tone, haemostatic system, oxidative processes, and plaque development, in selected in vitro, ex vivo, and in vivo models (3-6). Evidence was obtained that RWPE might improve vascular function mainly through nitric oxide (NO)-mediated mechanisms, interfere with haemostatic and oxidative processes involved in the progression of vascular damage, and modulate early events of atherosclerosis. These effects were studied on cellular and plasmatic blood components and on vascular function in experimental animal models. A study in 40 healthy volunteers, performed in Barcelona, showed a significant increase in HDL cholesterol (HDL-C) levels and a decreased oxidation of LDL after red wine ingestion (30 g alcohol daily for 4 weeks) as compared to the same amount of alcohol given as spirit. A significant fall was seen, after red wine, in the expression of several markers of cardiovascular risk measured on circulating cell surface or in plasma of volunteers. Finally, a meta-analysis of all available epidemiological studies indicated a significant negative association of moderate wine consumption (150-300 ml daily) with the risk of major cardiovascular events. In conclusion, this FAIR project contributed to the establishment of a biological plausibility to the epidemiological association of moderate wine consumption with prevention of cardiovascular disease. Red wine and RWPE altogether may prove to be beneficial against the major killer of European citizens.

Animals↗
PubMed1999

Platelet/polymorphonuclear leukocyte interaction: P-selectin triggers protein-tyrosine phosphorylation-dependent CD11b/CD18 adhesion: role of PSGL-1 as a signaling molecule.

Polymorphonuclear leukocyte (PMN) adhesion to activated platelets is important for the recruitment of PMN at sites of vascular damage and thrombus formation. We have recently shown that binding of activated platelets to PMN in mixed cell suspensions under shear involves P-selectin and the activated beta2-integrin CD11b/CD18. Integrin activation required signaling mechanisms that were sensitive to tyrosine kinase inhibitors.1 Here we show that mixing activated, paraformaldehyde (PFA)-fixed platelets with PMNs under shear conditions leads to rapid and fully reversible tyrosine phosphorylation of a prominent protein of 110 kD (P approximately 110). Phosphorylation was both Ca2+ and Mg2+ dependent and was blocked by antibodies against P-selectin or CD11b/CD18, suggesting that both adhesion molecules need to engage with their respective ligands to trigger phosphorylation of P approximately 110. The inhibition of P approximately 110 phosphorylation by tyrosine kinase inhibitors correlates with the inhibition of platelet/PMN aggregation. Similar effects were observed when platelets were substituted by P-selectin-transfected Chinese hamster ovary (CHO-P) cells or when PMN were stimulated with P-selectin-IgG fusion protein. CHO-P/PMN mixed-cell aggregation and P-selectin-IgG-triggered PMN/PMN aggregation as well as P approximately 110 phosphorylation were all blocked by antibodies against P-selectin or CD18. In each case PMN adhesion was sensitive to the tyrosine kinase inhibitor genistein. The antibody PL-1 against P-selectin glycoprotein ligand-1 (PSGL-1) blocked platelet/PMN aggregation, indicating that PSGL-1 was the major tethering ligand for P-selectin in this experimental system. Moreover, engagement of PSGL-1 with a nonadhesion blocking antibody triggered beta2-integrin-dependent genistein-sensitive aggregation as well as tyrosine phosphorylation in PMN. This study shows that binding of P-selectin to PSGL-1 triggers tyrosine kinase-dependent mechanisms that lead to CD11b/CD18 activation in PMN. The availability of the beta2-integrin to engage with its ligands on the neighboring cells is necessary for the tyrosine phosphorylation of P approximately 110.

Adult↗
PubMed1999

Modulation of haemostatic function and prevention of experimental thrombosis by red wine in rats: a role for increased nitric oxide production.

1. The effects of ethyl alcohol and wine (red and white) on haemostatic parameters and experimental thrombosis were studied in rats; NO was evaluated as a possible mediator of these effects. 2. We found that red wine (12% alcohol) supplementation (8.4 +/- 0.4 ml d-1 in drinking water, for 10 days) induced a marked prolongation of 'template' bleeding time (BT) (258 +/- 13 vs 132 +/- 13 s in controls; P < 0.001), a decrease in platelet adhesion to fibrillar collagen (11.6 +/- 1.0 vs 32.2 +/- 1.3%; P < 0.01) and a reduction in thrombus weight (1.45 +/- 0.33 vs 3.27 +/- 0.39 mg; P < 0.01). 3. Alcohol-free red wine showed an effect similar to red wine. In contrast, neither ethyl alcohol (12%) nor white wine (12% alcohol) affected these systems. 4. All these effects were also observed after red wine i.v. injection (1 ml kg-1 of 1:4 dilution) 15 min before the experiments. 5. The effects of red wine were prevented by the NO inhibitor, N omega nitro-L-arginine-methyl ester (L-NAME). L-arginine, not D-arginine, reversed the effect of L-NAME on red wine infusion. 6. Red wine injection induced a 3 fold increase in total radical-trapping antioxidant parameter values of rat plasma with respect to controls, while white wine and alcohol did not show any effect. 7. Our study provides evidence that red wine modulates primary haemostasis and prevents experimental thrombosis in rats, independently of its alcohol content, by a NO-mediated mechanism.

Administration, Oral↗
PubMed1999

Recent advances in platelet-polymorphonuclear leukocyte interaction.

Epidemiological evidence suggests a positive correlation between the number of PMN and the risk of ischemic vascular disease. The observation that activated PMN induce platelet activation my provide some biological plausibility to the role of PMN in thrombogenesis. Between other PMN products, cathepsin G, a protease released during PMN activation, is a potent platelet agonist. However, the antiproteinases present in plasma could virtually abolish its activity. Indeed it was shown that, when PMN were stimulated after interaction with platelets in mixed cell population, P-selectin-mediated platelet-PMN adhesion may result in the formation of a sequestered microenvironment in which cathepsin G activity is protected by antiproteases. P-selectin-mediated adhesion was also shown to facilitate the transcellular metabolism of arachidonic acid, resulting in increased production of both thromboxane B2 and leukotriene C4. PMN adhesion to activated platelets in mixed cell suspensions subjected to high shear rate can be modeled as an adhesion cascade involving a P-selectin-dependent recognition step followed by an adhesion-strengthening interaction mediated by the beta(2)-integrin Mac-1. Moreover, an intermediate tyrosine-kinase-dependent signal regulating beta(2)-integrin adhesiveness is required. Indeeed activated platelets express not only P-selectin but also different beta(2)-integrin ligands including fibrinogen and ICAM-2. Some of the functional responses elicited by P-selectin on PMN could be prevented by specific antibody to the P-selectin glycoprotein ligand-1, indicating that this adhesive receptor is able to transduce an 'outside-in' signal when engaged by the ligand. By using activated platelets, P-selectin-expressing CHO cells and soluble recombinant P-selectin, P-selectin was shown to trigger protein tyrosine phosphorylation in PMN and the tyrosine kinase-dependent function of Mac-1. In conclusion, adherence of activated platelets to PMN may be a key event in the sequence of thrombus formation. The recognition of the essential contribution of PMN beta(2)-integrins in addition to P-selectin in platelet-PMN adhesion provides an additional evidence to the broad range of function and mechanisms in which PMN integrins are involved and may be potential targets for pharmacological intervention.

Animals↗
PubMed1999

Platelet contribution to leukotriene production in inflammation: in vivo evidence in the rabbit.

The contribution of platelets to arachidonic acid transcellular metabolism may represent an important pathway of leukotriene (LT) production. The aim of this study was to investigate the role of platelets on LT production in an acute inflammatory model in the rabbit. Preliminary experiments showed that rabbit whole blood (5 ml) stimulated in vitro with the calcium ionophore A23187 produced LTB4 (52.7+/-13.9 ng) and the mixed 5,12-DiHETE (7.25+/-0.75 ng). In A23187-stimulated thrombocytopenic blood, LTB4 was significantly reduced to 19.5+/-8.6 ng and 5,12-DiHETE was undetectable. Peptido-LTs were undetectable in both conditions. In experiments using washed cells, addition of thrombin-activated platelets to fMLP-activated PMN resulted in the appearance of 5,12-DiHETE and in more than twofold increase of LTB4 synthesis. When 3H-arachidonic acid-labelled platelets were mixed with unlabelled PMN and challenged with fMLP and thrombin, radioactive LTB4 and 5,12-DiHETE were produced, indicating that platelet-derived arachidonic acid was utilized by PMN 5-lipoxygenase. Intravenous infusion of fMLP (2.5 nmol/kg/min) in the rabbit induced marked granulocytopenia, thrombocytopenia and increased TxB2 plasma concentrations within 3 min. Electron microscopy of lungs showed morphologically activated and aggregated platelets occluding the capillary lumen. Activation and recruitment of circulating cells was accompanied by the production of LTB4 (peak levels at 1 min: 30.0+/-9.5 ng/ml) and LTE4 (peak levels at 10 minutes: 77.8+/-11.6 ng/ml). The areas under the blood concentration-time curve (AUC, ng min/ml) corresponded to 812+/-182 and 3692+/-658 for LTB4 and LTE4, respectively. In immunologically thrombocytopenic rabbits, the AUC for LTB4 (86.0+/-23.0) and LTE4 (1165+/-542) were both significantly different from controls while in rabbits treated with an anti-leukocyte antiserum, both LTB4 and LTE4 were similar to controls. This experimental model provides in vivo evidence that platelets, involved in an acute inflammatory event contribute to the transcellular production of LTs.

Animals↗
PubMed1998

Effect of trans-resveratrol, a natural polyphenolic compound, on human polymorphonuclear leukocyte function.

1. Polymorphonuclear leukocytes (PMN) may contribute to the pathogenesis of acute coronary heart disease (CHD). 2. Epidemiological and laboratory evidence suggests that red wine, by virtue of its polyphenolic constituents, may be more effective than other alcoholic beverages in reducing the risk of CHD mortality. 3 The aim of the present study was to investigate the effects of trans-resveratrol (3,4',5-trihydroxy-trans-stilbene), a polyphenol present in most red wines, on functional and biochemical responses of PMN, upon in vitro activation. 4. trans-Resveratrol exerted a strong inhibitory effect on reactive oxygen species produced by PMN stimulated with 1 microM formyl methionyl leucyl phenylalamine (fMLP) (IC50 1.3+/-0.13 microM, mean+/-s.e.mean), as evaluated by luminol-amplified chemiluminescence. 5. trans-Resveratrol prevented the release of elastase and beta-glucuronidase by PMN stimulated with the receptor agonists fMLP (1 microM, IC50 18.4+/-1.8 and 31+/-1.8 microM), and C5a (0.1 microM, IC50 41.6+/-3.5 and 42+/-8.3 microM), and also inhibited elastase and beta-glucuronidase secretion (IC50 37.7+/-7 and 25.4+/-2.2 microM) and production of 5-lipoxygenase metabolites leukotriene B4 (LTB4), 6-trans-LTB4 and 12-trans-epi-LTB4 (IC50 48+/-7 microM) by PMN stimulated with the calcium ionophore A23187 (5 microM). 6. trans-Resveratrol significantly reduced the expression and activation of the beta2 integrin MAC-1 on PMN surface following stimulation, as revealed by FACS analysis of the binding of an anti-MAC-1 monoclonal antibody (MoAb) and of the CBRM1/5 MoAb, recognizing an activation-dependent epitope on MAC-1. Consistently, PMN homotypic aggregation and formation of mixed cell-conjugates between PMN and thrombin-stimulated fixed platelets in a dynamic system were also prevented by transresveratrol. 7. These results, indicating that trans-resveratrol interferes with the release of inflammatory mediators by activated PMN and down-regulates adhesion-dependent thrombogenic PMN functions, may provide some biological plausibility to the protective effect of red wine consumption against CHD.

Blood Platelets↗
PubMed1997

Kinetics of endogenous leukotriene B4 and E4 production following injection of the chemotactic peptide FMLP in the rabbit.

The kinetic profiles of leukotriene B4 (LTB4) and E4 (LTE4) after intravenous administration (30 nmol/kg) of the inflammatory peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) were evaluated in male rabbits. LTB4 and LTE4 reached the maximal concentration of 84.2 +/- 60.0 and 162.2 +/- 51.4 nmol/L (mean +/- s.d.), at 2 and 5 min, respectively. The first elimination phase for LTB4 and LTE4, after FMLP administration, showed an apparent half-life of 24.6 +/- 6.7 and 36.9 +/- 13.0 min, respectively. The area under the blood concentration-time curve (AUC, nmol min/L) of LTB4 and LTE4 was 2178 +/- 1591 and 7627 +/- 3052, respectively. LTE4 and N-ac-LTE4 were the major components excreted in the urine, mostly in the first time interval (0-12 h) of urinary collection after FMLP treatment; 11-trans-LTE4 was recovered in the second interval (12-24 h). Two other more polar compounds, potential metabolites, were recovered in the first interval of urine collection. Knowledge of the kinetic characteristics of endogenously produced leukotrienes may be useful in understanding the role of these eicosanoids in inflammatory and thrombotic disease, as well as in evaluating the efficacy of drugs designed to modulate their production and effect.

Animals↗
PubMed1997

Prolongation of bleeding time by acute hemolysis in rats: a role for nitric oxide.

The present study was aimed at clarifying the interaction between red blood cell trauma and bleeding observed in some clinical conditions. Acute hemolysis provoked by distilled water injection was followed by a significant prolongation of the "template" bleeding time in rats. Comparable effects were observed after injection of an isotonic lysate of washed red blood cells. N omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) formation from L-arginine, normalized bleeding time when given to rats before hemolysis induction. The occurrence of hemolysis decreased ex vivo platelet adhesion to collagen without affecting platelet aggregation and induced a transient drop in blood pressure, the latter occurring during the first minute after injection. L-NAME pretreatment increased ex vivo platelet adhesion but did not affect either platelet aggregation or fall in blood pressure. All the effects of L-NAME were blunted by treating the animals with the NO precursor L-arginine but not D-arginine. Incubation of the erythrocyte lysate with apyrase prevented the prolongation of bleeding time induced by the hemolysate. Moreover, ADP administration, at doses that did not increase hemoglobin levels, induced effects similar to those observed after hemolysis (on template bleeding time and ex vivo platelet adhesion), which were also reversed by L-NAME and restored by L-arginine. ADP is abundantly released from (hemo)lysed red blood cells and is known to stimulate release of NO, a potent vasodilator and inhibitor of platelet adhesion. ADP-dependent NO release could be responsible for bleeding time prolongation, due to abnormalities in platelet-vessel wall interaction, during acute hemolysis. Lysis of white blood cells may also contribute to prolongation of bleeding time. Because ADP could not be detected in these cells, we postulate that other mechanisms also can be involved in bleeding time prolongation after blood cell activation in vivo.

Adenosine Diphosphate↗
PubMed1997

Enhanced response to chemotactic activation of polymorphonuclear leukocytes from patients with heart valve replacement.

Artificial surfaces activate blood components. Since anticoagulant and antiplatelet therapy fail to abolish thromboembolic complications in patients with mechanical heart valve replacement (MHVR), other mechanisms might contribute to switch on a thrombotic event. We therefore investigated the reactivity to chemotactic activation of PMN from patients with MHVR. PMN responses were analyzed in 3 groups: 130 patients with MHVR and oral anticoagulant therapy, with or without aspirin, 57 patients on a comparable antithrombotic regimen, but without MHVR and 50 healthy subjects. In vitro studies showed that the release of cathepsin G and elastase from fMLP-stimulated PMN was significantly higher in the MHVR group, the leukocyte content of alpha 1-antitrypsin (an inhibitor of both enzymes) being similar in all three groups. CD11b expression after stimulation with fMLP was also significantly higher on PMN from MHVR patients than from control patients or healthy volunteers, while PMN CD11b basal expression was similar in all three groups. This increased PMN response in vitro in the absence of an obvious activation in vivo, may reflect a modified reactivity of circulating PMN passing through the artificial valves. Increased reactivity to local stimuli might allow PMN to participate in thrombus formation, despite conventional antithrombotic therapy.

Anticoagulants↗
PubMed1997

Different requirement of intracellular calcium and protein kinase C for arachidonic acid release and serotonin secretion in cathepsin G-activated platelets.

Previous studies have shown that platelet stimulation with cathepsin G rapidly results in cytoplasmic calcium ([Ca2+]i) increase and activation of protein kinase C (PKC). To elucidate the relationship between these two biochemical events and their relative contribution to the regulation of platelet response to cathepsin G, arachidonic acid (AA) release and serotonin (5HT) secretion were studied. Platelets made Ca2+-depleted and -permeable by treatment with A23187 were compared to intact platelets to better dissociate calcium changes from other receptor-stimulated events. AA release elicited by cathepsin G in intact platelets was prevented by the Ca2+ chelator BAPTA; in Ca2+-depleted, -permeable platelets AA was released in direct response to added Ca2+ and was not increased by simultaneous stimulation with cathepsin G. In intact platelets, PKC inhibition by Ro 31-8220 or PKC induction with PMA either enhanced or reduced, respectively, cathepsin G-induced AA release. Both BAPTA and Ro 31-8220 prevented 5HT secretion from intact platelets; however, in Ca2+-depleted, -permeable platelets, cathepsin G was able to evoke 5HT secretion and p47 phosphorylation independently of [Ca2+]i increase, both effects being hampered by Ro 31-8220. Ca2+ and PKC therefore regulate PLA2 activity and 5HT secretion in cathepsin G-stimulated platelets in a different manner: the former is mainly triggered by [Ca2+]i increase, while PKC represents the major factor in determining dense granule secretion.

Arachidonic Acid↗
PubMed1996

Platelet/polymorphonuclear leukocyte interaction in dynamic conditions: evidence of adhesion cascade and cross talk between P-selectin and the beta 2 integrin CD11b/CD18.

Adhesion between platelets and polymorphonuclear leukocytes (PMN) is a key event in thrombosis and inflammation. Double color fluorescence-activated cell sorter (FACS) analysis was used to determine the extent and kinetics of adhesion of thrombin-activated platelets to resting or activated PMN when mixed cell populations were incubated in dynamic conditions. Activated platelets bound very rapidly to PMN. Mixed cell conjugates reached a maximum at 1 minute and were reversible within 10 minutes. Platelet/PMN adhesion required both Ca2+ and Mg2+ and was markedly increased by the presence of Mn2+. The latter made mixed cell conjugates stable up to 10 minutes. Adhesion of platelets required metabolic activity of PMN and was abolished by tyrosine kinase inhibitors. Furthermore, adhesion of platelets to PMN resulted in binding of a monoclonal antibody (MoAb 24) known as beta 2 integrins "activation reporter." When PMN were activated by exogenous stimuli, the adhesion of platelets was markedly increased: fMLP induced a rapid and transient effect, while PMA resulted in a slower, but stable, increase in mixed conjugates formation. The hypothesis that activated PMN beta 2 integrins are able to bind a counter-receptor on platelets was directly demonstrated by the increase of mixed cell conjugates following PMN treatment with KIM127 and KIM185, two anti-CD18 antibodies able to induce the active conformation of beta 2 integrins. Consistently, two other anti-CD18, as well as an anti-CD11b inhibitory antibody abolished platelet/PMN adhesion. PMN beta 2 integrin activation was not the only mechanism for activated platelet/PMN adhesion to occur: indeed, this phenomenon could also be inhibited by two anti-P-selectin antibodies. Resting platelets did not adhere to resting PMN, but markedly adhered to fMLP- or PMA-activated PMN. Resting platelet/fMLP-activated PMN adhesion was abolished by anti-CD18 antibodies, but not by anti-P-selectin antibodies. In conclusion, activated platelet/PMN interaction can be modeled as an adhesion cascade involving a P-selectin-dependent recognition step and a functional signal. The latter proceeds through tyrosine kinase activation and enables a beta 2 integrin-dependent adhesion to a not yet identified counter-receptor constitutively expressed on platelet surface.

Antibodies, Monoclonal↗