The in vitro effects of verbascoside on human platelet aggregation.

Preliminary in vitro and animal studies have shown that verbascoside, a phenolic compound, may have several favourable biological activities, including an influence on endothelial function and on platelet aggregation. We sought to evaluate the effects of verbascoside, biotechnologically produced from plant cell cultures, on human platelet aggregation (PA). The blood from 40 aspirin-naïve volunteers with at least one cardiovascular risk factor was preincubated in vitro with verbascoside (1 and 2 mg/dL) and aspirin (100 µM). The blood from 20 patients with a prior diagnosis of coronary heart disease who were chronically assuming aspirin was preincubated in vitro with verbascoside (1 and 2 mg/dL). PA is measured with a light transmission aggregometry and multiplate analyzer. As compared to reference, preincubation with verbascoside resulted in a significant inhibition of adenosine diphosphate (ADP) and arachidonic acid (AA)-induced PA (p < 0.01 for both). Verbascoside 2 mg/dL did not show a stronger effect as compared to verbascoside 1 mg/dL (p = 0.4). As expected, the in vitro addition of aspirin reduced AA induced PA (p < 0.01), but not that induced by ADP (p = 0.5). The addition of verbascoside to the blood of aspirin-treated patients did not improve the values of PA after AA stimulus (p = 0.8), whereas it ensured a stronger inhibition after ADP stimulus (p < 0.01). Verbascoside in vitro affects PA by mildly inhibiting aggregation, triggered both by ADP and AA. These preliminary data, while intriguing, require confirmation in subjects receiving verbascoside orally in order to determine whether these findings are clinically relevant.

Interaction with heparin protects tissue transglutaminase against inactivation by heating and by proteolysis.

The considerable affinity of tissue transglutaminase for heparin was the basis for use of heparin-based affinity matrices for enzyme purification. Interaction of transglutaminase with heparin might mimic the physiological binding to membrane heparan sulfates, accounting for the limited but significant fraction of enzyme exposed at cell surface to crosslink ECM proteins. Exploring effects of heparin on transglutaminase activity and stability, we have noted that heparin only slightly affects activity in vitro, but the protein against heat treatment and proteolysis.

Oxygen, reactive oxygen species and tissue damage.

The diatomic molecule of oxygen contains two uncoupled electrons and can therefore undergo reduction, yielding several different oxygen metabolites, which are collectively called Reactive Oxygen Species or ROS. They are invariably produced in aerobic environments through a variety of mechanisms, which include electron "leakage" during biologic oxidations, action of flavin dehydrogenases and specific membrane associated secretion, as well as by physical activation of oxygen by irradiation, e.g. UV sun-light. Organisms have developed efficient protective mechanisms against excessive accumulation of ROS, which include superoxide anion, hydrogen peroxide and hydroxyl radical, since all these metabolites are highly reactive and affect almost every kind of organism, either directly or through conversion into other derivatives, notably NO-derived radicals or RNS. Depending on their tissue concentration they can either exert beneficial physiologic effects (control of gene expression and mitogenesis) or damage cell structures, including lipids and membranes, proteins and nucleic acids, leading to cell death. In this brief overview we summarize the present state-of-the-art, restricting the discussion to the role of ROS in physiology and pathology, not taking into account RNS. Discussion will focus on basic chemical and biochemical features of ROS, underlining how ROS can promote severe diseases, including neoplastic, cardiovascular and neurodegenerative diseases. This brief discussion should clarify the present huge interest in ROS, in the perspective to develop new and specific therapeutic approaches.

In vitro characterization of circulating endothelial progenitor cells isolated from patients with acute coronary syndrome.

BACKGROUND: The current understanding of the functional characteristics of circulating endothelial progenitor cells (EPC) is limited, especially in patients affected by cardiovascular diseases. In this study, we have analyzed the in vitro clonogenic capacity of circulating EPC, also known as endothelial colony-forming cells (ECFC), in patients with acute coronary syndrome (ACS), in comparison to the colony forming unit-endothelial-like cells (CFU-EC) of hematopoietic/monocytic origin. METHODOLOGY/PRINCIPAL FINDINGS: By culturing peripheral blood mononuclear cells (PBMC) of patients with ACS (n = 70), CFU-EC were frequently isolated (from 77% of ACS patients), while EPC/ECFC were obtained only in a small subset (13%) of PBMC samples, all harvested between 7-14 days after the acute cardiovascular event. Notably, ex-vivo generation of EPC/ECFC was correlated to a higher in vitro release of PDGF-AA by the corresponding ACS patient PBMC. By using specific endothelial culture media, EPC/ECFC displayed in vitro expansion capacity, allowing the phenotypic and functional characterization of the cells. Indeed, after expansion, EPC/ECFC exhibited a normal diploid chromosomal setting by FISH analysis and an immunophenotype characterized by: i) uniform positivity for the expression of CD105, CD31, CD146 and Factor VIII, i) variable expression of the CD34, CD106 and CD184 markers, and iii) negativity for CD45, CD90, CD117 and CD133. Of interest, in single-cell replanting assays EPC/ECFC exhibited clonogenic expansion capacity, forming secondary colonies characterized by variable proliferation capacities. CONCLUSION/SIGNIFICANCE: Our data indicate that a careful characterization of true EPC is needed in order to design future studies in the clinical autologous setting of patients with ACS.

Three-year follow-up of the MULTIcentre evaluation of Single high-dose Bolus TiRofiban versus Abciximab with Sirolimus-eluting STEnt or Bare-Metal Stent in Acute Myocardial Infarction StudY (MULTISTRATEGY).

BACKGROUND: The Multicentre Evaluation of Single high-dose Bolus TiRofiban versus Abciximab with Sirolimus-eluting Stent or Bare Metal Stent in Acute Myocardial Infarction Study [MULTISTRATEGY]) randomised 745 patients with ST-elevation myocardial infarction to receive high-dose bolus (HDB) tirofiban or abciximab infusion and sirolimus-eluting (SES) or uncoated-stent (BMS) implantation. Tirofiban was non-inferior to abciximab in terms of ST-segment resolution after intervention, whereas 8 month-major adverse cardiac events occurred in 14.5% in the BMS and 7.8% in the SES groups (P = 0.0039), reflecting a reduction of reintervention rates (10.2% vs. 3.2%). A three-year follow-up was performed to extend previous short- to mid-term findings. METHODS AND RESULTS: Complete data at 3 years was available for 736 patients (99%). All-cause mortality was 6.7% in the tirofiban and 7.8% in the abciximab (P = 0.56) and 7.5% in the BMS vs 7.0 in the SES groups, P = 0.79. The composite of all-cause death or MI was identical at 12.9% in tirofiban and abciximab groups, P = 0.99 and it occurred in 13.2% in the BMS vs. 12.6% in the SES groups (P = 0.83). The need for reintervention remained more than twice as common with BMS (13.7%; versus 6.2%, P = 0.0006). The cumulative rate of stent thrombosis (ST) did not differ. This is inspite of a higher very late definite, probable or possible ST thrombosis rate in the SES group. CONCLUSIONS: The 3-year follow-up of MULTISTRATEGY demonstrated comparable outcomes with HDB Tirofiban or abciximab and a sustained efficacy of SES to reduce reintervention with no difference in death, repeat MI or ST.

Prasugrel versus tirofiban bolus with or without short post-bolus infusion with or without concomitant prasugrel administration in patients with myocardial infarction undergoing coronary stenting: the FABOLUS PRO (Facilitation through Aggrastat By drOpping or shortening Infusion Line in patients with ST-segment elevation myocardial infarction compared to or on top of PRasugrel given at loading dOse) trial.

OBJECTIVES: The authors sought to compare the effect on inhibition of platelet aggregation (IPA) of prasugrel therapy versus tirofiban bolus with or without a post-bolus short drug infusion in ST-segment elevation myocardial infarction (STEMI) patients. BACKGROUND: The degree and rapidity of IPA after prasugrel alone with or without concomitant glycoprotein IIb/IIIa inhibition in STEMI patients is unknown. METHODS: A total of 100 STEMI patients randomly received prasugrel 60 mg versus 25 µg/kg tirofiban bolus with or without post-bolus 2-h infusion of tirofiban, with or without concomitant prasugrel. IPA at light transmission aggregometry was performed throughout 24 h. The primary endpoint was IPA stimulated with 20 µmol/l adenosine diphosphate (ADP) at 30 min. RESULTS: At 30 min, patients in the prasugrel group showed a significantly lower IPA to 20 µmol/l ADP stimulation as compared with tirofiban-treated patients (36 ± 35 vs. 87 ± 31, p < 0.0001). Similarly, patients taking prasugrel showed a suboptimal degree of platelet inhibition for at least 2 h compared with tirofiban patients. Post-bolus tirofiban infusion was necessary to maintain a high level of IPA beyond 1 h after bolus administration if concomitant clopidogrel was given, whereas the bolus-only tirofiban and concomitant prasugrel led to the higher and more consistent IPA levels after both ADP and thrombin receptor-activating peptide stimuli than either therapy alone. CONCLUSIONS: Our study shows that prasugrel administration leads to a suboptimal IPA for at least 2 h in STEMI patients. Yet, prasugrel, given in association with a bolus only of glycoprotein IIb/IIIa inhibitor, obviates the need of post-bolus infusion and almost completely abolishes residual variability of IPA after treatment. (Facilitation through Aggrastat By drOpping or shortening Infusion Line in patients with ST-segment elevation myocardial infarction compared to or on top of PRasugrel given at loading dOse [The FABOLUS PRO trial]; NCT01336348).

Prediction of 1-year clinical outcomes using the SYNTAX score in patients with acute ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention: a substudy of the STRATEGY (Single High-Dose Bolus Tirofiban and Sirolimus-Eluting Stent Versus Abciximab and Bare-Metal Stent in Acute Myocardial Infarction) and MULTISTRATEGY (Multicenter Evaluation of Single High-Dose Bolus Tirofiban Versus Abciximab With Sirolimus-Eluting Stent or Bare-Metal Stent in Acute Myocardial Infarction Study) trials.

OBJECTIVES: This study sought to evaluate the impact of SYNTAX score (SXscore), and compare its performance in isolation and combination with the PAMI (The Primary Angioplasty in Myocardial Infarction Study) score, for the prediction of 1-year clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention. BACKGROUND: Patients with STEMI were excluded from the original SYNTAX score (SXscore) algorithm. Therefore, the utility of using the SXscore in this patient group remains undefined. METHODS: SXscore was calculated retrospectively in 807 patients with STEMI enrolled in the randomized STRATEGY (Single High-Dose Bolus Tirofiban and Sirolimus-Eluting Stent Versus Abciximab and Bare-Metal Stent in Acute Myocardial Infarction) and MULTISTRATEGY (Multicenter Evaluation of Single High-Dose Bolus Tirofiban Versus Abciximab With Sirolimus-Eluting Stent or Bare-Metal Stent in Acute Myocardial Infarction Study) clinical trials. Clinical outcomes of all-cause death, reinfarction, and clinically driven target vessel revascularization were subsequently stratified according to SXscore tertiles: SX(LOW) ≤ 9 (n = 311), 9 < SX(MID) ≤ 16 (n = 234), SX(HIGH) >16 (n = 262). RESULTS: At 1-year follow-up, all clinical outcomes including mortality, mortality/reinfarction, major adverse cardiac events (MACE) (a composite of all-cause death, reinfarction and target vessel revascularization), and definite, definite/probable, and any stent thrombosis were all significantly higher in patients in the highest SXscore tertile. SXscore was identified as an independent predictor of mortality, MACE, and stent thrombosis out to 1-year follow-up. The combination SYNTAX-PAMI score led to a net reclassification improvement of 15.7% and 4.6% for mortality and MACE, respectively. The C-statistics for the SXscore, PAMI score, and the combined SYNTAX-PAMI score were 0.65, 0.81, and 0.73 for 1-year mortality, and 0.68, 0.64, and 0.69 for 1-year MACE, respectively. CONCLUSIONS: SXscore does have a role in the risk stratification of patients with STEMI having primary percutaneous coronary intervention; however, this ability can be improved through a combination with clinical variables. (Multicentre 2×2 Factorial Randomised Study Comparing Tirofiban Versus Abciximab and SES Versus BMS in AMI; NCT00229515).