Marek Postula

Genome-wide Association Study Using Pooled DNA to Identify Candidate Markers Mediating Susceptibility to Postoperative Nausea and Vomiting

Background:A family history has been established as a risk factor for postoperative nausea and vomiting (PONV), but the identities of susceptibility genes remain unknown. The goal of this study was to identify the genetic loci that may contribute to PONV susceptibility in an adult population. Methods:The authors performed a genome-wide association study involving pooling of DNA obtained from 122 patients with severe PONV and 129 matched controls. Each pool was hybridized to a single nucleotide polymorphism (SNP) microarray, and probe intensity was used to predict allele frequency. Differences in allele frequency between SNP in the PONV and control groups were ranked after accounting for the pooling error. The highest ranking SNPs were selected for individual genotyping in the subjects from whom the DNA pool was comprised and in the new verification cohort consisting of 208 subjects (104 PONV patients and 104 controls). Results:The authors identified 41 SNP targets showing substantial difference in allelic frequency between pools. These markers were first genotyped in the individual DNA samples from which the pools were comprised. The authors observed evidence for an association between PONV and 19 different loci in the genome. In the separate verification cohort, the association with PONV was observed for four SNPs. This association remained significant after correcting for multiple testing (P < 0.0023) for one SNP (rs2165870), which is located upstream of the promoter for the muscarinic acetylcholine receptor 3 subtype (CHRM3) gene. Conclusions:The authors performed the genome-wide association study for PONV using pooled DNA samples. Through individual genotyping, they confirmed association of at least one SNP that is predictive of PONV susceptibility.

Baseline platelet size is increased in patients with acute coronary syndromes developing early stent thrombosis and predicts future residual platelet reactivity. A case-control study

INTRODUCTION Pre-procedural predictors of early stent thrombosis (ST) and future response to platelet inhibitors are in demand. We sought to evaluate the impact of baseline platelet indices on the occurrence of early ST and future residual platelet reactivity. MATERIALS AND METHODS Hundred and eight patients with acute coronary syndromes (ACS) in whom stents were implanted were included: 36 consecutive ST cases and 72 matched controls. Platelet indices assessed with flow cytometry before stent implantation were retrieved from the departments data base. Residual platelet reactivity specific to aspirin (aspirin reaction units-ARU) and clopidogrel (P2Y12 reaction units-PRU) was assessed prospectively with VerifyNow under dual antiplatelet treatment. RESULTS Platelet size reported as mean platelet volume (MPV) or proportion of large platelets (LPLT) was significantly higher in ST cases compared with controls (10.4, 95% confidence intervals [CI], 10.1-10.8 vs. 9.7, CI, 9.5-9.9, P=0.0004 and 35.8, CI, 34.2-37.3 vs. 33.3, CI, 32.2-34.3, P=0.007, respectively). Dual aspirin and clopidogrel poor-responsiveness was diagnosed significantly more often in ST cases than in controls (19.6% vs. 1.4%, P=0.004), whereas no difference was observed for single aspirin or clopidogrel poor-responsiveness. A strong correlation was found between MPV and both, ARU (r=0.66, P<0.0001) and PRU (r=0.55, P<0.0001). Similarly, higher LPLT was associated with higher ARU (r=0.47, P<0.0001) and PRU (r=0.38, P=0.0001). CONCLUSIONS Baseline platelet size is increased in patients with ACS developing early ST and correlates with future residual platelet reactivity under aspirin and clopidogrel therapy. Dual but not isolated aspirin or clopidogrel poor-responsiveness appears to be associated with early ST.

Genetic determinants of platelet reactivity during acetylsalicylic acid therapy in diabetic patients: evaluation of 27 polymorphisms within candidate genes

Summary.  Aims: Decreased platelet responsiveness to acetylsalicylic acid (ASA) reported previously in diabetic patients could be attributed to patient‐based, clinical, genetic and cellular factors. The objective of the present study was to investigate the effect of the genomic polymorphism on the platelet reactivity in diabetic patients treated with ASA. Methods and results: The study cohort consisted of 295 Caucasians with diabetes type 2 who had been taking ASA tablets at the dose of 75 mg per day for at least 3 months for primary or secondary prevention of myocardial infarction (MI). Platelet reactivity analyzes were performed using VerifyNow ASA and PFA‐100 assays. Genotyping for the selected 27 single nucleotide polymorphisms (SNPs) within 19 genes was performed using a Sequenom iPLEX platform. The results indicate that the statistically significant differences in platelet reactivity were observed in the PFA‐100 assay for SNPs in following genes: TXBA2R (rs1131882), ADRA2A (rs4311994), PLA2G7 (rs7756935) and 9p21.3 (rs10120688) (P = 0.02, P = 0.03, P = 0.02, P = 0.03, respectively, all significance levels corrected for multiple comparisons). When using the VerifyNow ASA test, a weak nominal statistical significance (i.e. before multiple comparison testing) was observed for two SNPs in the GPVI gene: rs1671152 and rs1613662 [P = 0.025 (0.5) for both SNPs, corrected for multiple comparisons test]. Conclusions: The results from the present study suggest that the four analyzed genes may contribute to platelet reactivity measured with the PFA‐100 assay in the diabetic population treated with ASA.

Effect of ASA dose doubling versus switching to clopidogrel on plasma inflammatory markers concentration in patients with type 2 diabetes and high platelet reactivity: The AVOCADO study

BACKGROUND The aim of the study was to compare the effects of 2 strategies of antiplatelet treatment (i.e., 150 mg ASA vs. 75 mg clpoidogrel) on plasma level of inflammatory markers in type 2 diabetes mellitus (T2DM) patients with high platelet reactivity (HPR). METHODS Study cohort consisted of 304 T2DM patients on chronic ASA therapy (75 mg per day) participating in the Aspirin Versus/Or Clopidogrel in Aspirin-resistant Diabetics inflammation Outcomes (AVOCADO) study. Patients with HPR defined as Platelet Function Analyzer (PFA)-100 collagene/epinephrine closure time (CEPI-CT) < 193 s (n = 80) were randomized to 150 mg of ASA or 75 mg of clopidogrel in 2:3 ratio, respectively. Concentrations of the selected inflammatory markers, including tumor necrosis factor (TNF)-α, interleukin (IL)-6, solubleCD40 ligand (sCD40L), and high sensitivity C-reactive protein (hsCRP), were measured and compared in both treatment groups before and after 8 weeks of treatment in both groups. RESULTS Out of 234 patients included into final analysis, the total of 34.2% (n = 80) patients displayed HPR, of which 14.1% (n = 33) were randomized into 150 mg of ASA group and 20.1% (n = 47) into 75 mg of clopidogrel group. Treatment with clopidogrel was a positive predictor (stepwise multiple regression analysis) of reduction of sCD40L concentration (odds ratio [OR] 4.15; p = 0.013), while treatment with 150 mg ASA was a positive predictor of reduction of IL-6 concentration (OR 4.38; p = 0.033). There was no statistically significant differences between clopidogrel and ASA 150 mg treatment in respect to predictive value for decreased hsCRP concentrations or increased TNF-α concentrations. CONCLUSIONS Increasing the dose of ASA from 75 mg to 150 mg daily or switching ASA 75 mg to clopidogrel 75 mg daily may reduce concentrations of some inflammatory markers (in particular hsCRP, IL-6 and CD40L) in T2DM patients with HPR treated previously with 75 mg of ASA.

Perioperative exacerbation of valproic acid-associated hyperammonemia: a clinical and genetic analysis.

We present a case of significant deterioration of chronic hyperammonemia after general anesthesia for neurosurgery despite aggressive treatment. Preoperative evaluation demonstrated that hyperammonemia was most likely related to valproic acid treatment. Genomic analysis revealed that the patient was heterozygotic for a missense polymorphism in the carbamoyl phosphate synthase 1 gene (4217C>A, rs1047891). This mutation was previously suggested to be associated with chronic hyperammonemia. Replacement of threonine with asparagine decreases the activity of carbamoyl phosphate synthase in the urea cycle. Genetic screening can potentially identify a population at risk before initiation of antiepileptic therapy.

Novel antiplatelet agents in the prevention of cardiovascular complications – focus on ticagrelor

Atherothrombosis, thrombus formation as a result of atherosclerotic plaque rupture, is a major modern health problem, often underlying coronary artery disease, stroke, and peripheral arterial disease. After the treatment of an acute thrombotic episode, long-term therapy is warranted as a secondary prophylaxis of such events and their complications. Because of the importance of platelets’ involvement in the initiation and propagation of thrombosis, antiplatelet drugs have come to the forefront of atherothrombotic disease treatment. Dual antiplatelet therapy of aspirin plus clopidogrel – the current standard – has its benefits, but it also has its limitations with regard to its pharmacologic properties and adverse effects. For these reasons, within the last decade or so, the investigation of novel antiplatelet agents has prospered. Here, we review the main pathways through which platelets participate in acute thrombosis and the interruption of these pathways by using novel antiplatelet agents, including P2Y12 receptor antagonists (the recently approved prasugrel, the probable next-in-line ticagrelor, and others). The need for a more individualized patient therapy is evident; although most of the aforementioned pharmaceuticals have the potential to contribute to this, their clinical utility remains to be seen.

The effect of doubling the dose of acetylsalicylic acid (ASA) on platelet function parameters in patients with type 2 diabetes and platelet hyperreactivity during treatment with 75 mg of ASA: a subanalysis of the AVOCADO study

BACKGROUND Individuals with diabetes are at 2- to 4-fold higher risk of cardiovascular disease than those without diabetes. High platelet reactivity (HPR) plays a pivotal role in atherothrombotic complications of diabetes. Polish and American diabetes associations recommend treating high-risk diabetic patients with low doses of acetylsalicylic acid (ASA) in primary and secondary prevention of cardiovascular events. Unfortunately, some patients show HPR despite treatment with ASA. AIM To determine the effect of doubling the dose of ASA on platelet reactivity in patients with type 2 diabetes and HPR despite treatment of with 75 mg of ASA. METHODS 304 type 2 diabetes patients treated with 75 mg of ASA were enrolled into the prospective, randomised, open-label Aspirin Versus/Or Clopidogrel in Aspirin-resistant Diabetics inflammation Outcomes (AVOCADO) study. Platelet reactivity was assessed by Platelet Function Analyser (PFA)-100®, VerifyNow® Aspirin Assay, and serum thromboxane B2 (sTXB2) and urinary 11-dehydrothromboxane B2 (u11dhTXB2) level measurements. Patients with HPR determined by collagen/epinephrine-induced closure time (CEPI-CT) measured by PFA-100® were randomised in a 2:3 ratio to receive 150 mg of ASA (Group 1) or 75 mg of clopidogrel (Group 2), respectively. Platelet reactivity was assessed at baseline and after 8 weeks of treatment. RESULTS Complete clinical data and blood samples were ultimately available for 260 of 304 patients initially enrolled to the study. Subsequently, six patients were excluded from the analysis based on suspected ASA non-compliance (sTXB2 level > 7200 pg/mL). Among 254 patients finally included into analysis, HPR was found in 90 (35.4%) patients of whom 38 patients were randomised to Group 1 and 52 patients to Group 2. Doubling the dose of ASA resulted in a significant CEPI-CT prolongation (Delta 111 s, p < 0.001) and reduction of sTXB2 level (Delta -101.3 pg/mL, p = 0.001) but did not significantly affect results of other platelet function tests. CONCLUSIONS Doubling the dose of ASA improved platelet reactivity in patients with type 2 diabetes and HPR.

Emerging treatments in type 2 diabetes: focus on canagliflozin

Type 2 diabetes mellitus (T2DM) is a prevalent metabolic disorder, which affects more than 300 million people globally. The common effect of uncontrolled diabetes is the state of hyperglycemia, which results from beta-cell dysfunction as well as insulin resistance, which is accompanied with microvascular and macrovascular complications. As hyperglycemia defines diabetes, glycemic control is fundamental to the management of diabetes. Sodium glucose co-transporter 2 inhibitors (SGLT2) are a new group of oral antidiabetic medications that act by blocking the reabsorption of glucose, causing it to be excreted in the urine. Canagliflozin was the first SGLT2 inhibitor to be approved in the US by the Food and Drug Administration for the treatment and control of T2DM and on September 19, 2013, the Committee for Medicinal Products for Human Use of the European Medicines Agency adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Invokana®. Canagliflozin is a SGLT2 inhibitor, which acts upon the proximal tubules of the kidneys and reduces the renal threshold for glucose. It is highly selective, binding 250 times more potently to SGLT2 than sodium glucose co-transporter 1 inhibitor. This action allows a higher amount of glucose to be excreted within the urine, causing the patient’s plasma glucose level to be decreased and indirectly causing weight loss. Among the most common adverse events are hypoglycemia, headache, nausea, female genital and urinary tract infections, nasopharyngitis, and transient postural dizziness. Given its high efficacy in reducing hyperglycemia and good safety profile as either monotherapy or an add-on treatment to metformin, sulfonylureas, or insulin, canagliflozin seems to be a promising antihyperglycemic drug. Nevertheless, further large-scale and long-term studies should be conducted to evaluate the impact of canagliflozin on cardiovascular risk in T2DM patients.

The effect of off-pump coronary artery bypass grafting on platelet activation in patients on aspirin therapy until surgery day §

OBJECTIVE Antiplatelet therapy is a class I indication in perioperative care after coronary artery bypass grafting to prevent graft occlusion. We sought to determine whether continuation of aspirin until surgery day suppresses platelet activity in the early period after off-pump coronary artery bypass grafting (OPCAB). MATERIAL AND METHODS Forty-two patients at mean age of 62.5 (+/-7.9) years were included. Average risk rate (EuroScore logistic) was 2.2 (+/-1.7) %. In all patients collagen/epinephrine stimulated platelet plug formation (closure time, CT) (CEPI-CT, s) using a platelet function analyzer (PFA-100), troponin I (TnI), creatine kinase-MB (CK-MB), ST segment elevation were evaluated a day before surgery, 4h after chest closure, 24 and 120 h after surgery. RESULTS Preoperative mean CEPI-CT was 224.8 (+/-79.7)s. In 13 (30%) patients aspirin resistance (CEPI-CT<163 s.) was observed. In 4, 24 and 120 h time points CEPI-CT was significantly reduced: 164.4 (+/-79), 168.5 (+/-83.3) and 167.5 (+/-80.4), respectively (p<0,001). TnI and CK-MB (ng/ml) levels raised in respective time points: 4 h (0.26 range 4; 1.9 range 6), 24 h (0.2 range 6; 2.6 range 8), 120 h (0.04 range 2; 0.6 range 5). ST segment elevation (mV) changed in time: 4h (0.7 range 3.5), 48 h (0.7 range 2.8) and 120 h after surgery (0.2 range 1.5). There were no significant correlations between CEPI-CT and TnI, CK-MB, ST segment elevation found. CONCLUSION Aspirin therapy continued until surgery day does not protect against acute platelet activation in patients after OPCAB.

Metformin treatment may be associated with decreased levels of NT-proBNP in patients with type 2 diabetes

PURPOSE Individuals with type 2 diabetes (T2DM) are at increased risk of cardiovascular disease, including heart failure (HF). In patients with T2DM elevated serum concentrations of the N-terminal fragment of pro-B-type natriuretic peptide (NT-proBNP) correlate with cardiovascular morbidity and mortality. We aimed to identify predictors of increased serum NT-proBNP levels in patients with T2DM. METHODS The study included 185 patients with T2DM treated with either oral antidiabetic agents (49.7%) or insulin (17.8%), or both (32.5%). We divided the patients into two groups: with high (>200 pg/mL) and low (≤200 pg/mL) NT-proBNP concentrations. RESULTS We found differences between the patients with high and low NT-proBNP levels including age, prevalence of dyslipidemia and HF, history of previous myocardial infarction (MI), heart rate, hemoglobin level, platelet count, creatinine, urea and uric acid concentrations, use of beta-blockers, loop diuretics, metformin and insulin. In a multivariate analysis metformin was a negative predictor of increased NT-proBNP concentration. Age, history of HF and decreased estimated glomerular filtration rate (eGFR) were positive predictors. We found no correlation between NT-proBNP serum concentration and insulin treatment or history of coronary artery disease or MI. CONCLUSION Metformin correlates with lower concentrations of NT-proBNP in patients with T2DM.