The Anopheles gambiae ATP-binding cassette transporter family: phylogenetic analysis and tissue localization provide clues on function and role in insecticide resistance.

The role of ATP-binding cassette (ABC) transporters in conferring insecticide resistance has received much attention recently. Here we identify ABC transporters differentially expressed in insecticide-resistant populations of the malaria vector, Anopheles gambiae. Although we found little evidence that the orthologues of the multidrug resistance proteins described in other species are associated with resistance in An. gambiae we did identify a subset of ABC proteins consistently differentially expressed in pyrethroid-resistant populations from across Africa. We present information on the phylogenetic relationship, primary sites of expression and potential role of ABC transporters in mediating the mosquito's response to insecticides. Furthermore we demonstrate that a paralogous group of eight ABCG transporters, clustered on chromosome 3R, are highly enriched in the legs of An. gambiae mosquitoes, consistent with a proposed role for this ABC subfamily in transport of lipids to the outer surface of the cuticle. Finally, antibodies raised against one of the most highly expressed ABC transporters in adult females, ABCG7 (AGAP009850), localized this transporter to the pericardial cells. These data will help prioritize members of this gene family for further localization and functional validation studies to identify the in vivo function of these transporters in the mosquito and determine whether elevated expression of members of this family contribute to insecticide resistance.

Instant loading with intraoral welding technique and PRAMA implants: a new prosthetic approach.

When splinting multiple implants passive fit of the framework should be achieved to avoid excessive force distribution on the implants. Recently, a protocol was suggested for immediate loading of multiple implants by welding a titanium bar to implant abutments directly in the oral cavity so as to create a customized, precise and passive metal-reinforced provisional restoration. The intraoral welding technique subsequently proves to be a successful option in the full-arch immediate restorations of the mandible and maxilla. The aim of this article is to present a case report in which a new prosthetic approach, using trans-mucosal implants, is described. Dental implants are instantly loaded with a provisional prosthesis supported by an intraoral welded titanium framework to obtain a precise passive fit of the immediate loaded prosthesis.

Short-term in vivo modifications of platelet NADPH oxidase 2 (NOX2) and prostaglandin F2α in HIV-1 patients on abacavir-based therapies.

OBJECTIVES: The aim of the study was to investigate the in vivo effect of abacavir (ABC) on platelet oxidative stress. METHODS: We performed a randomized pilot study including 39 HIV-1-infected patients, 17 on zidovudine/lamivudine (ZDV/3TC) and 22 on tenofovir/emtricitabine (TDF/FTC). Ten patients on ZDV/3TC and eight patients on TDF/FTC were randomly allocated to switching the nucleoside backbone to ABC/3TC. At baseline and after 6 months, platelet oxidative stress was assessed by platelet NADPH oxidase 2 (NOX2)-derived peptide (sNOX2-dp), a marker of NOX2 activation, and platelet prostaglandin F2α (8-iso-PGF2α ). Platelet activation was measured by soluble CD40L (sCD40L). RESULTS: At baseline, no differences between ZDV/3TC or TDF/FTC recipients were found. After 6 months, patients switching from ZDV/3TC showed a decrease of sNOX2-dp (from 20.9±5.7 to 12.5±3.8 pg/ml, p=0.002) and 8-iso-PGF2α (from 154.3±41.9 to 122.9±28.0 pmol/l, p=0.025). No effects on platelet oxidative stress biomarkers were observed in subjects from TDF/FTC, who showed a significant increase in blood glucose (p=0.043) and total cholesterol (p=0.027). ABC showed no effect on sCD40L levels in both groups. CONCLUSIONS: ABC reduced platelet sNOX2-dp and 8-iso-PGF2α in HIV-1 subjects switching from ZDV/3TC but not in those from TDF/FTC after 6 months. No changes in platelet activation were found in both groups.

Enhanced Soluble Serum CD40L and Serum P-Selectin Levels in Primary Aldosteronism.

Primary aldosteronism (PA) is one of the most frequent forms of secondary hypertension, associated with atherosclerosis and higher risk of cardiovascular events. Platelets play a key role in the atherosclerotic process. The aim of the study was to evaluate the platelet activation by measuring serum levels of soluble CD40L (sCD40L) and P-selectin (sP-selectin) in consecutive PA patients [subgroup: aldosterone-secreting adrenal adenoma (APA) and bilateral adrenal hyperplasia (IHA)], matched with essential hypertensive (EH) patients. The subgroup of APA patients was revaluated 6-months after unilateral adrenalectomy. In all PA group, we measured higher serum levels of both sP-selectin (14.29±9.33 pg/ml) and sCD40L (9.53±4.2 ng/ml) compared to EH patients (9.39±5.3 pg/ml and 3.54±0.94 ng/ml, respectively; p<0.001). After removal of APA, PA patients showed significant reduction of blood pressure (BP) values, plasma aldosterone (PAC) levels and ARR-ratio, associated with a significant reduction of sP-selectin (16.74±8.9 pg/ml vs. 8.1±3.8 pg/ml; p<0.01) and sCD40L (8.6±1 ng/ml vs. 5.24±0.94 ng/ml; p<0.001). In PA patients, we found a significant correlation between sP-selectin and sCD40L with PAC (r=0.52, p<0.01; r=0.50, p<0.01, respectively); this correlation was stronger in APA patients (r=0.54; p<0.01 r=0.63; p<0.01, respectively). Our results showed that PA is related to platelet activation, expressed as higher plasma values of sCD40L and sP-selectin values. Surgical treatment and consequent normalization of aldosterone secretion was associated with significant reduction of sCD40L and sP-selectin values in APA patients.

Effect of L-carnitine on oxidative stress and platelet activation after major surgery.

BACKGROUND: The surgical/anesthesia trauma is associated with an increased production of reactive oxygen species (ROS). This enhanced oxidative stress leads to cell damage resulting in various complications such as sepsis, myocardial injury and increased mortality. The aim of this study was to investigate the role of antioxidant treatment with l-carnitine in oxidative stress and platelet activation in patients undergoing major abdominal surgery. METHODS: Forty patients scheduled for abdominal surgery were randomly allocated to l-carnitine, administered with a rapid infusion (0.05 g/kg) diluted in 250 ml of saline solution, vs. placebo treatment just before the surgical intervention. At baseline and after treatment, oxidative stress was evaluated by detection of circulating levels of soluble NOX2-derived peptide (sNOX2-dp), a marker of NADPH oxidase activation, and by analyzing platelet ROS formation. Platelet activation was studied by dosing sCD40L. RESULTS: We observed an increase of soluble sNOX2-dp, sCD40L and ROS production in the placebo group compared with the baseline after the surgical intervention. Conversely, in the l-carnitine-treated group, sNOX2-dp, sCD40L and ROS production did not significantly differ from the baseline. A linear correlation analysis showed that Δ of ROS correlated with Δ of sNOX2 (R(s) =0.817; P<0.001) and Δ of sCD40L (R(s) =0.780; P<0.001). Multiple linear regression analysis showed that the only independent predictive variable associated with Δ of ROS was Δ of serum NOX2 levels (SE=0.05; standardized coefficient ß=1.075; P<0.001). CONCLUSION: Our findings suggest that l-carnitine could be helpful in modulating oxidative stress and platelet activation during major abdominal surgery-dependent oxidative damage.

Peripheral arterial disease has a strong impact on cardiovascular outcome in patients with acute coronary syndromes: from the START Antiplatelet registry.

BACKGROUND: Peripheral arterial disease (PAD) was reported to increase the risk of new cardiovascular events in patients with acute coronary syndromes (ACS). However, most of the evidence comes from randomized clinical trials. We aimed to assess the impact of PAD on cardiovascular outcome and treatment decisions in ACS patients in a current real-life setting. METHODS: START-ANTIPLATELET is a multicenter registry enrolling ACS patient. Baseline clinical characteristics and treatment at discharge were recorded and follow-up was repeated at 6-months and 1-year. PAD was defined as intermittent claudication and/or previous revascularization. RESULTS: Among 1442 patients enrolled, 103 (7.1%) had PAD. PAD patients were older (71.8 ± 10.6vs66.2 ± 12.6 yrs., p < 0.0001), more frequently hypertensive (90.3vs68.6%, p< 0.0001), hypercholesterolemic (66vs52%, p= 0.037), diabetic (51.5vs24%, p= 0.0001), obese (28.2vs19.3%, p= 0.029) and with previous TIA (7.8vs2.8%, p= 0.005) or stroke (11.7vs3.1%, p< 0.0001). Clinical presentation and acute treatment were similar in non-PAD and PAD patients, but the latter were discharged significantly less frequently on dual antiplatelet therapy (DAPT) (68.9vs85%, p= 0.005). After a median follow-up time of 11.1 months, major cardio/cerebrovascular event-free survival [MACCE, including cardiovascular death, MI, TIA and stroke, target-vessel revascularization (TVR) and major arterial ischemic events] was significantly shorter (9.0vs11.2 months, p= 0.02; HR 3.2, 2.4-8.4) in PAD patients and net adverse cardiovascular events (NACE = MACCE plus major hemorrhages) were significantly more frequent (19.1%vs10.5%, p = 0.049). CONCLUSIONS: PAD identifies a subgroup of ACS patients at significantly increased cardiovascular risk, but these patients tend to be undertreated. Patients admitted for ACS should be screened for PAD and optimal medical therapy at discharge should be implemented.

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.

Effect of coffee drinking on platelets: inhibition of aggregation and phenols incorporation.

Epidemiological studies indicate a J-shaped relationship linking coffee consumption and cardiovascular risk, suggesting that moderate coffee consumption can be beneficial. Platelet aggregation is of critical importance in thrombotic events, and platelets play a major role in the aetiology of several CVD. The aim of this study was to evaluate the effect of coffee drinking on platelet aggregation ex vivo, using caffeine as control. A crossover study was performed on ten healthy subjects. In two different sessions, subjects drank 200 ml coffee, containing 180 mg caffeine, or a capsule of caffeine (180 mg) with 200 ml water. Platelets were separated from plasma at baseline and 30 and 60 min after coffee drinking. Platelet aggregation was induced with three different agonists: collagen, arachidonic acid and ADP. Coffee drinking inhibited collagen (P < 0.05 from baseline at time 30 min) and arachidonic acid (P < 0.05 from baseline at time 60 min) induced platelet aggregation. Caffeine intake did not affect platelet aggregation induced by the three agonists. Coffee consumption induced a significant increase of platelet phenolic acids (likely present as glucuronate and sulphate derivatives), caffeic acid, the principal phenolic acid in coffee, raising from 0.3 (SEM 0.1) to 2.4 (SEM 0.6) ng/mg (P < 0.01). Caffeine was not detectable in platelets. Coffee drinking decreases platelet aggregation, and induces a significant increase in phenolic acid platelet concentration. The antiplatelet effect of coffee is independent from caffeine and could be a result of the interaction of coffee phenolic acids with the intracellular signalling network leading to platelet aggregation.

Aging and Adherence to the Mediterranean Diet: Relationship with Cardiometabolic Disorders and Polypharmacy.

OBJECTIVES: To investigate the association between adherence to the Mediterranean Diet (Med-Diet), cardiometabolic disorders and polypharmacy. DESIGN: Cross-sectional study. SETTING: Geriatrics outpatient clinic, Policlinico Umberto I, Sapienza University of Rome. PARTICIPANTS: 508 patients (219 male, 289 female) aged 50 to 89 who were evaluated for cardiovascular and metabolic disorders. METHODS AND MEASUREMENTS: Patients underwent a comprehensive medical assessment including medical history and the use of medications. Adherence to Med-Diet was assessed using the validated Med-Diet 14-item questionnaire; for the analysis, patients were divided in high (≥8) and medium-low (<8) adherence. Polypharmacy was defined as taking ≥5 medications. RESULTS: 476 patients completed the study. Mean age was 70.4 years; 58% female. Median Med-Diet score was 8 (interquartile range, 6-9). Patients with medium-low adherence had higher body mass index (p=0.029) and higher prevalence of arterial hypertension (p<0.001), previous coronary (p=0.002) and cerebrovascular events (p=0.011), diabetes, (p<0.001) and dyslipidemia (p=0.001) compared to those at high adherence. Med-Diet score decreased with the number of cardiometabolic disorders (p<0.001). The prevalence of polypharmacy was 39%. Consumption of olive oil (p=0.005), vegetables, (p<0.001), wine (p=0.017), legumes (p=0.028), fish (p=0.046) and nuts (p=0.045) were all inversely associated with the overall number of medications. In a multivariable regression model, medium-low adherence to Med-Diet was independently associated to polypharmacy (O.R.:1.859; 95% CI 1.142 to 3.025; p=0.013), after adjusting for possible confounding factors. CONCLUSION: Med-Diet was inversely associated with cardiometabolic disorders and with polypharmacy, suggesting that improved Med-Diet adherence might potentially delay the onset of age-related health deterioration and reduce the need of multiple medications.

Oxidative stress-mediated platelet CD40 ligand upregulation in patients with hypercholesterolemia: effect of atorvastatin.

OBJECTIVES: We speculated that in patients with hypercholesterolemia CD40L overexpression could depend on low-density lipoprotein (LDL)-induced enhanced intraplatelet formation of O(2)*(-) and statin could reduce platelet CD40L via interference with platelet O(2)*(-) production. BACKGROUND: CD40L is a protein with inflammatory and thrombotic properties. CD40L is upregulated in platelets from hypercholesterolemic (HC) patients but the underlying mechanism is unclear. METHODS: Collagen-induced platelet CD40L and platelet O(2)*(-) expression were investigated in 40 HC patients and 40 healthy subjects. HC patients were then randomized to either a diet (n = 20) (group A) or atorvastatin 10 mg day (n = 20) (group B); the above variables were measured at baseline and after 3 and 30 days of treatment. O(2)*(-) and CD40L were also measured in vitro in LDL-treated platelets with or without nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor or atorvastatin added. RESULTS: Compared with controls, HC patients showed higher values of platelet CD40L (P < 0.001) and O(2)*(-) (P < 0.001). Platelet CD40L was significantly correlated with O(2)*(-) (P < 0.001). The interventional trial showed no changes in group A and a significant and parallel decrease in platelet CD40L (P < 0.001) and O(2)*(-) (P < 0.001) in group B. In vitro studies demonstrated that LDL-induced platelet CD40L and GP IIb/IIIa (PAC1 binding) activation via the NADPH oxidase pathway. CD40L upregulation was counteracted by atorvastatin in a dose-dependent fashion. CONCLUSIONS: This study suggests that in patients with hypercholesterolemia platelet CD40L is upregulated via NADPH oxidase-dependent O(2)*(-) generation. Atorvastatin downregulated CD40L with an oxidative stress-mediated mechanism likely involving platelet NADPH oxidase, an effect that seemed to be independent of its cholesterol-lowering action.

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.

Assessment of risk factors for candidemia in non-neutropenic patients hospitalized in Internal Medicine wards: A multicenter study.

BACKGROUND: An increasing prevalence of candidemia has been reported in Internal Medicine wards (IMWs). The aim of our study was to identify risk factors for candidemia among non-neutropenic patients hospitalized in IMWs. METHODS: A multicenter case-control study was performed in three hospitals in Italy. Patients developing candidemia (cases) were compared to patients without candidemia (controls) matched by age, time of admission and duration of hospitalization. A logistic regression analysis identified risk factors for candidemia, and a new risk score was developed. Validation was performed on an external cohort of patients. RESULTS: Overall, 951 patients (317 cases of candidemia and 634 controls) were included in the derivation cohort, while 270 patients (90 patients with candidemia and 180 controls) constituted the validation cohort. Severe sepsis or septic shock, recent Clostridium difficile infection, diabetes mellitus, total parenteral nutrition, chronic obstructive pulmonary disease, concomitant intravenous glycopeptide therapy, presence of peripherally inserted central catheter, previous antibiotic therapy and immunosuppressive therapy were factors independently associated with candidemia. The new risk score showed good area under the curve (AUC) values in both derivation (AUC 0.973 95% CI 0.809-0.997, p<0.001) and validation cohort (0.867 95% CI 0.710-0.931, p<0.001). A threshold of 3 leads to a sensitivity of 87% and a specificity of 83%. CONCLUSION: Non-neutropenic patients admitted in IMWs have peculiar risk factors for candidemia. A new risk score with a good performance could facilitate the identification of candidates to early antifungal therapy.

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.

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.

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.

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.

Extra virgin olive oil use is associated with improved post-prandial blood glucose and LDL cholesterol in healthy subjects.

OBJECTIVES: Extra virgin olive oil (EVOO) is a key component of the Mediterranean diet and seems to account for the protective effect against cardiovascular disease. However, the underlying mechanism is still elusive. DESIGN: We tested the effect of EVOO, added to Mediterranean-type meal, on post-prandial glycemic and lipid profile. SUBJECTS: Post-prandial glycemic and lipid profile were investigated in 25 healthy subjects who were randomly allocated in a cross-over design to a Mediterranean-type meal added with or without 10 g EVOO (first study), or Mediterranean-type meal with EVOO (10 g) or corn oil (10 g; second study). Glycemic profile, which included glucose, insulin, dipeptidyl-peptidase-4 (DPP-4) protein and activity, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), and lipid profile, which included, low-density lipoprotein (LDL) cholesterol (LDL-C), oxidized LDL (ox-LDL), triglycerides and high-density lipoprotein (HDL) cholesterol (HDL-C), were analyzed before and 2 h after the meal. RESULTS: In the first study, 2 h after meal, subjects who assumed a meal with EVOO had significantly lower blood glucose (P<0.001), DPP-4 protein (P<0.001) and activity (P<0.001), LDL-C (P<0.001) and ox-LDL (P<0.001) and higher insulin (P<0.05), GLP-1 (P<0.001) and GIP (P<0.05) compared with those without EVOO. The second study showed that compared with corn oil, EVOO improved both glycemic and lipid profile. Thus, a significantly smaller increase of glucose (P<0.05), DPP4 protein (P<0.001) and activity (P<0.05) and higher increase of insulin (P<0.001) and GLP-1 (P<0.001) were observed. Furthermore, compared with corn oil, EVOO showed a significantly less increase of LDL-C (P<0.05) and ox-LDL (P<0.001). CONCLUSIONS: We report for the first time that EVOO improves post-prandial glucose and LDL-C, an effect that may account for the antiatherosclerotic effect of the Mediterranean diet.

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.

Concomitant activation of Gi and Gq protein-coupled receptors does not require an increase in cytosolic calcium for platelet aggregation.

U46619 is a potent platelet agonist, its binding to the thromboxane A2 receptor resulting in Gq-binding protein-mediated responses; nevertheless, it is unable to cause platelet aggregation, unless released ADP is present. In this study we demonstrate that Gi activation is the step U46619 lacks to cause platelet aggregation; in fact, when platelets were treated with an ADP scavenger system, the response to U46619 was restored by the addition of epinephrine, which activates platelets via a Gi protein. The concomitant activation of Gi and Gq proteins does not require increased cytosolic calcium to cause aggregation, as assessed by the fact that platelets treated with the intracellular calcium chelator BAPTA were able to respond to U46619 provided ADP or epinephrine was present. Moreover, as the calcium ionophore ionomycin, at low concentrations, potentiated the response to U46619 but not to epinephrine, we may conclude that calcium influx preferentially activates a Gi downstream signalling pathway.

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.