Search

During the past 20 years, we have witnessed the following trends in aspirin usage: (i) a “dropping” trend, characterized by the early discontinuation of low-dose aspirin from dual antiplatelet therapy or triple antithrombotic therapy (oral anticoagulation plus dual antiplatelet therapy in patients with atrial fibrillation) following an acute coronary syndrome or after percutaneous coronary intervention; (ii) a “combinatorial” trend, featuring the addition of a lower dose of a P2Y12 inhibitor or direct oral anticoagulant drug to low-dose aspirin for the long-term treatment of stable patients with atherosclerotic cardiovascular disease; and (iii) a “repurposing” trend, characterized by growing interest in the oncologic community to assess the chemopreventive effect of aspirin against certain types of cancers (particularly of the gastrointestinal tract), both as primary prevention and adjuvant therapy. The aim of this review is to present the mechanistic rationale underlying these trends, discuss the design and findings of trials testing novel treatments or new therapeutic applications of aspirin, and report on the ISTH Congress results on this topic.

Background: Impaired glucose tolerance (IGT) is associated with increased cardiovascular morbidity and mortality. Enhanced thromboxane (TX)-dependent platelet activation plays a pivotal role in atherothrombosis and characterizes type 2 diabetes mellitus (DM). Whether this also pertains to IGT is currently unknown. We investigated whether TXA2 -dependent platelet activation, as reflected by 11-dehydro-TXB2 (TXM) urinary excretion, is comparably abnormal in IGT as in DM, is persistent over long-term follow-up, changes as a function of metabolic disease progression, and is influenced by food intake. Methods: We prospectively investigated subjects with IGT (n = 48) and two control groups with DM diagnosed either less than 12 months (n = 60) or 12 months or more (n = 58). Results: Baseline TXM excretion was comparable between subjects with IGT and DM, with no evidence of a circadian variation. During a 36-month follow-up, urinary TXM excretion was stable over time in the DM groups, while tended to increase in subjects with IGT. Increasing urinary TXM excretion over time was observed in the subjects who progressed to diabetes vs nonprogressors. Conclusions: We conclude that TXA2 -dependent platelet activation was at least as high in IGT as in patients with DM and further increased over time, especially in those who progressed to overt diabetes.

Low-dose aspirin is recommended by the U.S. Preventive Services Task Force for primary prevention of colorectal cancer in certain individuals. However, broader implementation will require improved precision prevention approaches to identify those most likely to benefit. The major urinary metabolite of PGE2, 11a-hydroxy-9,15-dioxo-2,3,4,5-tetranor-prostane-1,20-dioic acid (PGE-M), is a biomarker for colorectal cancer risk, but it is unknown whether PGE-M is modifiable by aspirin in individuals at risk for colorectal cancer. Adults (N 1⁄4 180) who recently underwent adenoma resection and did not regularly use aspirin or NSAIDs were recruited to a double-blind, placebo-controlled, randomized trial of aspirin at 81 or 325 mg/day for 8–12 weeks. The primary outcome was postintervention change in urinary PGE-M as measured by LC/MS. A total of 169 participants provided paired urine samples for analysis. Baseline PGE-M excretion was 15.9 = 14.6 (mean = S.D, ng/mg creatinine). Aspirin significantly reduced PGE-M excretion (=4.7 = 14.8) compared with no decrease (0.8 = 11.8) in the placebo group (P 1⁄4 0.015; mean duration of treatment 1⁄4 68.9 days). Aspirin significantly reduced PGE-M levels in participants receiving either 81 (-15%; P 1⁄4 0.018) or 325 mg/day (-28%; P < 0.0001) compared with placebo. In 40% and 50% of the individuals randomized to 81 or 325 mg/day aspirin, respectively, PGE-M reduction reached a threshold expected to prevent recurrence in 10% of individuals. These results support that aspirin significantly reduces elevated levels of PGE-M in those at increased colorectal cancer risk to levels consistent with lower risk for recurrent neoplasia and underscore the potential utility of PGE-M as a precision chemoprevention biomarker. The ASPIRED trial is registered as NCT02394769.

Background: Impaired glucose tolerance (IGT) is associated with increased cardiovascular morbidity and mortality. Enhanced thromboxane (TX)-dependent platelet activation plays a pivotal role in atherothrombosis and characterizes type 2 diabetes mellitus (DM). Whether this also pertains to IGT is currently unknown. We investigated whether TXA2-dependent platelet activation, as reflected by 11-dehydro-TXB2 (TXM) urinary excretion, is comparably abnormal in IGT as in DM, is persistent over long-term follow-up, changes as a function of metabolic disease progression, and is influenced by food intake. Methods: We prospectively investigated subjects with IGT (n = 48) and two control groups with DM diagnosed either less than 12 months (n = 60) or 12 months or more (n = 58). Results: Baseline TXM excretion was comparable between subjects with IGT and DM, with no evidence of a circadian variation. During a 36-month follow-up, urinary TXM excretion was stable over time in the DM groups, while tended to increase in subjects with IGT. Increasing urinary TXM excretion over time was observed in the subjects who progressed to diabetes vs nonprogressors. Conclusions: We conclude that TXA2-dependent platelet activation was at least as high in IGT as in patients with DM and further increased over time, especially in those who progressed to overt diabetes.

N/A

Contains fulltext : 200583.pdf (publisher's version ) (Closed access)

Contains fulltext : 200583.pdf (publisher's version ) (Closed access)

Contains fulltext : 200583.pdf (publisher's version ) (Closed access)

Once-daily (od), low-dose aspirin (75–100 mg) is recommended to reduce the thrombotic risk of patients with essential thrombocytemia (ET). This practice is based on data extrapolated from other high-risk patients and an aspirin trial in polycythemia vera, with the assumption of similar aspirin pharmacodynamics in the two settings. However, the pharmacodynamics of low-dose aspirin is impaired in ET, reflecting accelerated renewal of platelet cyclooxygenase (COX)-1. ARES is a parallel-arm, placebo-controlled, randomized, dose-finding, phase II trial enrolling 300 ET patients to address two main questions. First, whether twice or three times 100 mg aspirin daily dosing is superior to the standard od regimen in inhibiting platelet thromboxane (TX)A2 production, without inhibiting vascular prostacyclin biosynthesis. Second, whether long-term persistence of superior biochemical efficacy can be safely maintained with multiple vs. single dosing aspirin regimen. Considering that the primary study end point is serum TXB2, a surrogate biomarker of clinical efficacy, a preliminary exercise of reproducibility and validation of this biomarker across all the 11 participating centers was implemented. The results of this preliminary phase demonstrate the importance of controlling reproducibility of biomarkers in multicenter trials and the feasibility of using serum TXB2 as a reliable end point for dose-finding studies of novel aspirin regimens.

Graft failure occurs in a sizeable proportion of coronary artery bypass conduits. We herein review relevant current evidence to give an overview of the incidence, pathophysiology, and clinical consequences of this multifactorial phenomenon. Thrombosis, endothelial dysfunction, vasospasm, and oxidative stress are different mechanisms associated with graft failure. Intrinsic morphological and functional features of the bypass conduits play a role in determining failure. Similarly, characteristics of the target coronary vessel, such as the severity of stenosis, the diameter, the extent of atherosclerotic burden, and previous endovascular interventions, are important determinants of graft outcome and must be taken into consideration at the time of surgery. Technical factors, such as the method used to harvest the conduits, the vasodilatory protocol, the storage solution, and the anastomotic technique, also play a major role in determining graft success. Furthermore, systemic atherosclerotic risk factors, such as age, sex, diabetes mellitus, hypertension, and dyslipidemia, have been variably associated with graft failure. The failure of a coronary graft is not always correlated with adverse clinical events, which vary according to the type, location, and reason for failed graft. Intraoperative flow verification and secondary prevention using antiplatelet and lipid-lowering agents can help reducing the incidence of graft failure.

The aim of the present review is to analyze how thinking about the cardiovascular safety of nonsteroidal antiinflammatory drugs has evolved during the past two decades, and discuss to what extent the additional information from the Prospective Randomized Evaluation of Celecoxib Integrated Safety Versus Ibuprofen or Naproxen study may alter our current mechanistic understanding and/or clinical practice.

The mechanism of action of low-dose aspirin in the prevention of colorectal cancer (CRC) remains largely hypothetical. We aimed to compare the effects of low-dose aspirin (100 mg/day for 7 days) given to 40 individuals undergoing CRC screening on the extent of cyclooxygenase (COX)-1 acetylation at serine-529 (AceCOX-1), in blood platelets vs. colorectal mucosa, at 7 (group 1) and 24 h (group 2) after dosing. A significantly (P < 0.01) lower %AceCOX-1 was detected in colonic and rectal mucosa (average 64%) vs. platelets (average 75%) in both groups. This effect was associated with an average 46% (P < 0.01) and 35% (P < 0.05) reduction in prostaglandin (PG) E2 levels and phosphorylated S6 (p-S6) levels, respectively. Rectal mucosal levels of p-S6/S6 significantly (P < 0.01) correlated with PGE2. These findings demonstrate that low-dose aspirin produces long-lasting acetylation of COX-1 and downregulation of p-S6 in human colorectal mucosa, an effect that may interfere with early colorectal carcinogenesis.

Item does not contain fulltext

Item does not contain fulltext

Item does not contain fulltext

The endothelium-derived peptide, endothelin, has been shown to exert powerful constrictor activity in both isolated and in situ coronary arteries. Recent in vitro data on isolated cardiac myocytes suggest that the substance might also possess electrophysiologic properties. We investigated the possibility that endothelin (ET-1) may exert proarrhythmic effects when infused selectively in the coronary circulation of open-chest-anesthetized dogs. Animals were instrumented for the measurement of left anterior descending (LAD) or left circumflex (LCX) coronary artery blood flow, left systolic ventricular pressure (LSVP), dP/dtmax, mean arterial pressure (MAP), and epicardial electrocardiogram (ECG; three leads). Data were recorded during infusion (2 min) of saline (n = 5) or increasing doses of endothelin (5-80 pmol/kg) given selectively in either the LCX (n = 10) or the LAD (n = 10). When infused into the LCX, endothelin produced a dose-dependent decrease in flow (40 +/- 23% at 80 pmol/kg, mean +/- SD, p less than 0.01) with a concomitant increase in coronary resistance and a decrease in dP/dtmax and MAP. ECG changes typical of myocardial ischemia paralleled the decrease in flow and culminated in ventricular fibrillation at the highest dose (80% of dogs). Endothelin caused similar hemodynamic effects when infused in the LAD, but fatal arrhythmias occurred for lower doses and for little or no change in coronary blood flow. Thirty percent of the animals died at 10 and 60% died at 20 pmol/kg, doses that induced only a moderate decrease (8 +/- 7 and 21 +/- 12%, respectively) in LAD total blood flow. Ventricular tachycardia always preceded ventricular fibrillation and death.(ABSTRACT TRUNCATED AT 250 WORDS)

COX-2 influences megakaryopoiesis

Item does not contain fulltext

Item does not contain fulltext

Item does not contain fulltext

platelet fucntion and aspirin intake

PURPOSE: This study aimed to assess whether haplotypes in XRCC1 and SNPs in OGG1 and XRCC3 were associated with an increased risk of developing breast cancer (BC) and early adverse reactions after radiotherapy. METHODS: 43 Italian breast cancer patients and 31 healthy controls were genotyped for XRCC1(-77T-->C,194,399), OGG1-326 and XRCC3-241 by RFLP-PCR. RESULTS: XRCC1-77T-->C, XRCC1-194, OGG1 and XRCC3 were not associated with BC. On the contrary, we found a significant association (p or=3 SNPs [OR = 2.72 (0.99-7.39), p = 0.04]. CONCLUSION: In our study, the 399-Gln allele of XRCC1 increased significantly the risk of BC and it may act as a dominant allele [Arg/Arg vs. (Gln/Gln + Arg/Gln), OR = 4.67 (95% CI 1.65-13.23), p = 0.005]. The combination of variant alleles at codon 399 and in position -77 could affect XRCC1 protein activity, impairing genome integrity and promoting cancer occurrence. Also, the number of SNPs in several genes involved in BER and HRR mechanisms made higher the risk of sporadic BC. We can conclude that genetic variants in multiple repair pathways may have a joint or additive effect in cancer risk.

Progression to acute myeloid leukemia/myelodysplastic syndromes (AML/MDS) is a possible evolution of polycythemia vera (PV), but whether some patients are at increased natural risk for this complication and how much the contribution of pharmacologic cytoreduction can affect the natural course of the disease remain uncertain. The European Collaboration on Low-dose Aspirin in Polycythemia Vera (ECLAP) prospective project included 1638 patients with PV. AML/MDS was diagnosed in 22 patients after a median of 2.5 years from recruitment in the study and a median of 8.4 years from the diagnosis of PV. Variables associated with progression to AML/MDS were assessed using different models of multivariate analysis. Older age was confirmed as the main independent risk factor (hazard ratio [HR], 4.30; 95% confidence interval [95% CI], 1.16-15.94; P = .0294), whereas overall disease duration failed to reach statistical significance (more than 10 years: HR, 1.91; 95% CI, 0.64-5.69; P = .2466). Exposure to P32, busulphan, and pipobroman (HR, 5.46; 95% CI, 1.84-16.25; P = .0023), but not to hydroxyurea (HU) alone (HR, 0.86; 95% CI, 0.26-2.88; P = .8021), had an independent role in producing an excess risk for progression to AML/MDS compared with treatment with phlebotomy or interferon.

Contains fulltext : 58492.pdf (publisher's version ) (Closed access)

Item does not contain fulltext

1 oktober 2004, Item does not contain fulltext

Contains fulltext : 58492.pdf (publisher's version ) (Closed access)

Item does not contain fulltext

01 oktober 2004, Item does not contain fulltext

Item does not contain fulltext

The two isoforms of cyclooxygenase (COX) catalyze the initial step in the formation of biologically important prostanoids, such as prostaglandin (PG) E2, and thromboxane (TX) A2, in a variety of pathophysiologic processes. These include modulation of the inflammatory reaction, gastrointestinal (GI) cytoprotection and ulceration, angiogenesis and cancer, hemostasis and thrombosis, renal hemodynamics, and progression of kidney disease. Thus, it is not surprising that drugs inhibiting the activity of COX isozymes may have desirable as well as untoward effects on a variety of human diseases. Low-dose aspirin provides a paradigm of COX-isozyme-selective and cell-specific inhibition, by virtue of its short half-life and its ability to inactivate COX irreversibly (1). Other nonsteroidal anti-inflammatory drugs (NSAIDs) lack these unique pharmacokinetic and pharmacodynamic features and do not usually achieve the same degree of persistent platelet COX-1 inhibition as is obtained with low-dose aspirin. The coxib drugs, such as rofecoxib and celecoxib, were developed to spare COX-1 activity in GI mucosa and platelets, and this is achieved more or less effectively depending upon the biochemical selectivity of the individual agents (2). There is no evidence that coxibs inhibit COX-2 at sites different from those normally inhibited by nonaspirin NSAIDs, although the functional consequences of COX-2 inhibition may vary in the face of unopposed COX-1 activity at sites of cell-cell interactions. Here, we discuss the beneficial and harmful consequences of selective COX-1 versus COX-2 inhibition and suggest a mechanistic interpretation of their major clinical read-outs. A leading theme is that the extent and persistence of platelet COX-1 inhibition represent a major determinant of the efficacy and safety of the currently available classes of COX inhibitors. It should be emphasized that the relationships between inhibition of COX-isozyme activity, reduced prostanoid formation, and chan

BACKGROUND AND PURPOSE: It has been suggested that daily intake of aspirin is associated with a reduction of cognitive decline, both in normal and in demented subjects, but the mechanism is unclear. We have therefore studied the relationship between thromboxane (TX) A(2) biosynthesis, as reflected by the urinary excretion of 11-dehydro-TXB(2), and the presence of dementia in patients after acute stroke. METHODS: Patients from the Rotterdam Stroke Databank were screened for dementia between 3 and 9 months after stroke. Patients had a full neurological examination, neuropsychological screening, and, if indicated, extensive neuropsychological examination. Criteria used for the diagnosis of dementia were from the Diagnostic and Statistical Manual of Mental Disorders, Third Edition (Revised). Urine samples were taken at the time of screening. Urinary 11-dehydro-TXB(2) was measured by means of a previously validated radioimmunoassay. RESULTS: Dementia was diagnosed in 71 patients, and urine samples were available for 62. Median value (range) of 11-dehydro-TXB(2) was 399 (89 to 2105) pmol/mmol creatinine for demented patients versus 273 (80 to 1957) for 69 controls with stroke but without dementia (P=0.013). No difference was found between 44 patients with vascular dementia, 404 (89 to 2105) pmol/mmol creatinine, and 18 patients with Alzheimer's disease plus cerebrovascular disease, 399 (96 to 1467) pmol/mmol creatinine (P=0.68). In a stepwise logistic regression analysis, in which possible confounders such as use of antiplatelet medication, cardiovascular risk factors, and type of stroke were taken into account, increased urinary excretion of 11-dehydro-TXB(2) remained independently related to the presence of dementia (OR 1.12, 95% CI 1.03 to 1.22 per 100 pmol/mmol creatinine). The difference in metabolite excretion rates between demented and nondemented patients was most prominent within the subgroup of ischemic stroke patients who received aspirin (P<0.01). CONCLUSIONS

BACKGROUND AND PURPOSE: Enhanced thromboxane (TX) biosynthesis has previously been reported in the acute phase after ischemic stroke. We investigated whether enhanced urinary excretion of 11-dehydro-TXB2, a noninvasive index of platelet activation, was present in the chronic phase after a transient ischemic attack (TIA) or stroke, including intracerebral hemorrhage. METHODS: We obtained a single urinary sample from 92 patients between 3 and 9 months after onset of stroke or TIA. The urinary excretion of the major enzymatic metabolite of TXA2, 11-dehydro-TXB2, was measured by a previously validated radioimmunoassay. The excretion rates were compared with those of 20 control patients with nonvascular neurological diseases. RESULTS: Urinary 11-dehydro-TXB2 averaged 294+/-139, 413+/-419, and 557+/-432 pmol/mmol creatinine for patients with TIA, ischemic stroke, and intracerebral hemorrhage, respectively; the values were higher in all subgroups (P<0.01) than that in control patients (119+/-66 pmol/mmol). Increased 11-dehydro-TXB2 excretion was present in 59% of all patients, in 60% (P<0.001) of patients with TIA, in 56% (P<0.001) of patients with ischemic stroke, and in 73% (P<0.001) of patients with intracerebral hemorrhage. Atrial fibrillation, no aspirin use, and severity of symptoms at follow-up contributed independently to the level of 11-dehydro-TXB2 excretion in a multiple linear regression analysis. CONCLUSIONS: Platelet activation is often present in patients in the chronic phase after stroke, including those with intracerebral hemorrhage. Persistent platelet activation, which is associated with atrial fibrillation and poor stroke outcome, can be substantially suppressed by aspirin treatment.

Prostaglandins (PGs) are lipid-derived mediators of rapid and localized cellular responses. Given the role of PG in supporting thymic T cell development, we investigated the expression of the PG synthases, also known as cyclooxygenases (COX)-1 and -2, in the biosynthesis of PGs in thymic stromal cell lines. The predominant isozyme expressed in cortical thymic epithelial cells was COX-1, while COX-2 predominated in the medulla. IFN-gamma up-regulated expression and activity of COX-2 in medullary cells, in which COX-2 was expressed constitutively. In contrast, IFN-gamma down-regulated COX-1 activity, but not expression, in cortical cells. Stromal cells support T cell development in the thymus, although the mediators of this effect are unknown. Selective inhibition of COX-2, but not COX-1, blocked the adhesion of CD4+CD8+ and CD4+CD8- thymocytes to medullary cell lines. No effect of the inhibitors was observed on the interactions of thymocytes with cortical epithelial lines. These data further support the differential regulation of COX-1 and COX-2 expression and function in thymic stromal cells. PGs produced by COX-2 in the medullary thymic stroma may regulate the development of thymocytes by modulating their interaction with stromal cells.

BACKGROUND AND PURPOSE: Both platelet activation and lipid peroxidation are potential sources of vasoactive eicosanoids that can be produced via the cyclooxygenase pathway, ie, thromboxane (TX) A2, or by free radical-catalyzed peroxidation of arachidonic acid, ie, isoprostanes. We investigated the biosynthesis of TXA2 and F2-isoprostanes, as reflected by the urinary excretion of 11-dehydro-TXB2 and 8-epi-prostaglandin (PG) F2 alpha respectively, in 62 consecutive patients (30 men, 32 women; mean age, 67 +/- 14 years) with acute ischemic stroke. METHODS: At least two consecutive 6-hour urine samples were obtained during the first 72 hours after onset of symptoms. Urinary eicosanoids were measured by previously described radioimmunoassays. RESULTS: Repeated periods of enhanced thromboxane biosynthesis were found in 52% of patients. Urinary 11-dehydro-TXB2 averaged 221 +/- 207 (mean +/- SD; n = 197; range, 13 to 967) pmol/mmol creatinine in 30 patients treated with cyclooxygenase inhibitors (mostly aspirin) at the time of study versus 392 +/- 392 (n = 186; range, 26 to 2533) in 32 untreated patients (P < .001). The corresponding values for 8-epi-PGF2 alpha excretion were 74 +/- 42 (range, 14 to 206) and 83 +/- 65 (range, 24 to 570) pmol/mmol creatinine (P > .05). The correlation between the two metabolites was moderate in both untreated patients (r = .41, P < .001) and patients with cyclooxygenase inhibitors (r = .31, P < .001). In a multiple regression analysis, increased thromboxane production was independently associated with severity of stroke on admission, atrial fibrillation, and treatment with cyclooxygenase-inhibiting drugs. CONCLUSIONS: We conclude that during the first few days after an acute ischemic stroke (1) platelet activation occurs repeatedly in a cyclooxygenase-dependent fashion; (2) platelet activation is not associated with concurrent changes in isoprostane biosynthesis; (3) platelet activation is independently associated with stroke severity and at

Several "in vitro" and "in vivo" studies indicate that heparin administration may affect platelet function. In this study we investigated the effects of prophylactic heparin on thromboxane (Tx)A2 biosynthesis "in vivo", as assessed by the urinary excretion of major enzymatic metabolites 11-dehydro-TxB2 and 2,3-dinor-TxB2. Twenty-four patients who were candidates for cholecystectomy because of uncomplicated lithiasis were randomly assigned to receive placebo, unfractionated heparin, low molecular weight heparin or unfractionated heparin plus 100 mg aspirin. Measurements of daily excretion of Tx metabolites were performed before and during the treatment. In the groups assigned to placebo and to low molecular weight heparin there was no statistically significant modification of Tx metabolite excretion while patients receiving unfractionated heparin had a significant increase of both metabolites (11-dehydro-TxB2: 3844 +/- 1388 vs 2092 +/- 777, p < 0.05; 2,3-dinor-TxB2: 2737 +/- 808 vs 1535 +/- 771 pg/mg creatinine, p < 0.05). In patients randomized to receive low-dose aspirin plus unfractionated heparin the excretion of the two metabolites was largely suppressed thus suggesting that platelets are the primary source of enhanced thromboxane biosynthesis associated with heparin administration. These data indicate that unfractionated heparin causes platelet activation "in vivo" and suggest that the use of low molecular weight heparin may avoid this complication.