Impact of CYP2C19 Polymorphisms on Clinical Outcomes and Antiplatelet Potency of Clopidogrel in Caucasian Poststroke Survivors.

BACKGROUND: Variable response after clopidogrel is well documented and may affect major adverse clinical events after stroke. Impact of CYP2C19 genetic polymorphisms is an established marker linked to variable response after clopidogrel. However, the association of certain genetic polymorphisms with prediction of major adverse clinical events following stroke still remains controversial, especially in Caucasians. STUDY QUESTION: The primary aim was to evaluate the impact of CYP2C19 allele *2 in heterozygote form on major adverse clinical events in Caucasian poststroke survivors treated with clopidogrel. The secondary aim was to analyze the potential link between CYP2C19 genetic polymorphism and variable response after clopidogrel. STUDY DESIGN: One hundred thirty patients of Caucasian origin following documented ischemic stroke were included. Platelet reactivity was assessed by light transmittance aggregometry (LTA) and matched with various CYP2C19 loss-of-function genetic polymorphisms and major adverse clinical events (composite of vascular deaths, stroke/transient ischemic attack, and myocardial infarction). RESULTS: Over the mean follow-up of 14.9 months, 19 patients experienced major adverse clinical events. The risk of major adverse clinical events was nearly 3-fold in loss-of-function allele carriers (hazard ratio = 2.904; 95% confidence interval, 1.083-7.786; P = 0.013), whereas the risk of ischemic stroke or transient ischemic attack alone was also higher (hazard ratio = 3.170; 95% confidence interval, 1.281-7.849; P = 0.034). Platelet activity was strongly associated with allele *2 status (rs = 0.21, P = 0.016) but not with other genetic polymorphisms. Carriers of allele*2 exhibited lower platelet response to adenosine diphosphate-mean LTA (30.1% vs. 42.0%; P = 0.017). There were no significant differences in LTA results with other agonists. Strong association of increase in adenosine diphosphate-induced aggregation with diabetes mellitus (rs = 0.20, P = 0.023), increasing age (rs = 0.23, P = 0.008), and conversely diminishing over increased weight (rs = 0.23, P = 0.009) was also detected. The carriers of other gene allele variants lack uniformed impact on variable response after clopidogrel. CONCLUSIONS: Even heterozygous CYP2C19*2 allele carriers among Caucasian patients after ischemic stroke had a higher risk of major adverse clinical events. The LTA, however, did not predict major adverse clinical events. The exact clinical utility of these findings is still uncertain and requires large outcome-driven randomized trial in Caucasians for proof of concept.

Ischemic Postconditioning and Nitric Oxide Administration Failed to Confer Protective Effects in a Porcine Model of Extracorporeal Cardiopulmonary Resuscitation.

The protective effects of ischemic postconditioning (IPC) and nitric oxide (NO) administration have been demonstrated in several ischemic scenarios. However, current evidence regarding the effect of IPC and NO in extracorporeal cardiopulmonary resuscitation remains lacking. Fifteen female swine (body weight 45 kg) underwent veno-arterial extracorporeal membrane oxygenation (ECMO) implantation; cardiac arrest-ventricular fibrillation was induced by rapid ventricular pacing. After 20 min of cardiac arrest, blood flow was restored by increasing the ECMO flow rate to 4.5 L/min. The animals (five per group) were then randomly assigned to receive IPC (three cycles of 3 min ischemia and reperfusion), NO (80 ppm via oxygenator), or mild hypothermia (HT; 33.0°C). Cerebral oximetry and aortic blood pressure were monitored continuously. After 90 min of reperfusion, blood samples were drawn for the measurement of troponin I, myoglobin, creatine-phosphokinase, alanine aminotransferase, neuron-specific enolase, cystatin C, and reactive oxygen metabolite (ROM) levels. Significantly higher blood pressure and cerebral oxygen saturation values were observed in the HT group compared with the IPC and NO groups (P < 0.05). The levels of troponin I, myoglobin, creatine phosphokinase, and alanine aminotransferase were significantly lower in the HT group (P < 0.05); levels of neuron-specific enolase, cystatin C, and ROM were not significantly different. IPC and NO were comparable in all monitored parameters. The results of the present study indicate that IPC and NO administration are not superior interventions to HT for the maintenance of blood pressure, cerebral oxygenation, organ protection, and suppression of oxidative stress following extracorporeal cardiopulmonary resuscitation.

The bleeding risk during warfarin therapy is associated with the number of variant alleles of CYP2C9 and VKORC1 genes.

BACKGROUND: Warfarin is commonly used for the treatment and prevention of arterial and venous thromboembolism but its use is hindered by the risk of bleeding. The main reason for this risk is a narrow therapeutic index and a wide response variability after warfarin treatment. These shortcomings affect clinical outcomes including bleeding complications and may be associated with variant polymorphisms in the CYP2C9 and VKORC1 genes. AIM: It was the aim of this study to assess the impact of the total variant allele count of CYP2C9 and VKORC1 genes on bleeding related to warfarin treatment. METHODS: In a retrospective cohort-design study, patients were genotyped for polymorphisms in genes CYP2C9 (*1, *2, *3) and VKORC1 (haplotype A, B). Extensive clinical data were obtained. Adjusted hazard ratios (HR) for the occurrence of major bleeding events (MBE) were counted separately for the induction and maintenance phases of warfarin therapy. RESULTS: Out of the 329 patients in our clinical database, 194 patients were eligible and included in the analysis. MBE occurred in 51 patients (26.3%) during a mean follow-up of 26 months: 6 patients (11.8%) experienced early MBE during warfarin initiation, and 45 MBE occurred during the maintenance phase. The adjusted HR for MBE risk for patients with any CYP2C9 variant allele was 1.962 [95% confidence interval (CI) 1.08-3.56, p = 0.027]; for the VKORC1 AA haplotype, HR was 1.841 (95% CI 0.97-3.48, p = 0.06), while for 3 variant allele carriers of both genes, HR was 4.34 (95% CI 1.95-9.65, p < 0.001). Despite the insignificant association of the VKORC1 genotype with bleeding in our study, we have noted a warfarin dose-dependent effect with risk significance ascending: CYP2C9 *1/*1 + VKORC1 B/B < CYP2C9 *1/*1 + VKORC1 A/B < CYP2C9 *1/*2 + VKORC1 B/B. CONCLUSION: Patients who are carriers of 3 variant alleles of the genes CYP2C9 and VKORC1 exhibited a significantly higher risk of MBE during the initiation and maintenance phases of warfarin therapy. Vigilant and careful management of patients with a higher variant allele count, including switching to newer anticoagulants, could be considered in this high-risk cohort.

Mild therapeutic hypothermia is superior to controlled normothermia for the maintenance of blood pressure and cerebral oxygenation, prevention of organ damage and suppression of oxidative stress after cardiac arrest in a porcine model.

BACKGROUND: Mild therapeutic hypothermia (HT) has been implemented in the management of post cardiac arrest (CA) syndrome after the publication of clinical trials comparing HT with common practice (ie, usually hyperthermia). Current evidence on the comparison between therapeutic HT and controlled normothermia (NT) in CA survivors, however, remains insufficient. METHODS: Eight female swine (sus scrofa domestica; body weight 45 kg) were randomly assigned to receive either mild therapeutic HT or controlled NT, with four animals per group. Veno-arterial extracorporeal membrane oxygenation (ECMO) was established and at minimal ECMO flow (0.5 L/min) ventricular fibrillation was induced by rapid ventricular pacing. After 20 min of CA, circulation was restored by increasing the ECMO flow to 4.5 L/min; 90 min of reperfusion followed. Target core temperatures (HT: 33°C; NT: 36.8°C) were maintained using the heat exchanger on the oxygenator. Invasive blood pressure was measured in the aortic arch, and cerebral oxygenation was assessed using near-infrared spectroscopy. After 60 min of reperfusion, up to three defibrillation attempts were performed. After 90 min of reperfusion, blood samples were drawn for the measurement of troponin I (TnI), myoglobin (MGB), creatine-phosphokinase (CPK), alanin-aminotransferase (ALT), neuron-specific enolase (NSE) and cystatin C (CysC) levels. Reactive oxygen metabolite (ROM) levels and biological antioxidant potential (BAP) were also measured. RESULTS: Significantly higher blood pressure and cerebral oxygenation values were observed in the HT group (P<0.05). Sinus rhythm was restored in all of the HT animals and in one from the NT group. The levels of TnI, MGB, CPK, ALT, and ROM were significantly lower in the HT group (P<0.05); levels of NSE, CysC, and BAP were comparable in both groups. CONCLUSIONS: Our results from animal model of cardiac arrest indicate that HT may be superior to NT for the maintenance of blood pressure, cerebral oxygenation, organ protection and oxidative stress suppression following CA.

CSF and serum orosomucoid (alpha-1-acid glycoprotein) in patients with multiple sclerosis: a comparison among particular subgroups of MS patients.

INTRODUCTION: To compare cerebrospinal fluid (CSF) and serum orosomucoid (alpha-1-acid glycoprotein-AAG) concentrations in various subgroups of patients with multiple sclerosis (MS). MATERIALS AND METHODS: CSF and serum AAG concentrations, AAG quotient (i.e., CSF AAG/serum AAGx10(3)) and index were determined in a group of 59 patients with clinically definite or probable MS. Patients were subdivided according to the disease form, disease severity according to an expanded disability status scale (EDSS), its treatment, disease duration and sex. RESULTS: CSF AAG was increased in 52.5% of the patients and AAG quotient even in 64.4%. An increase in the CSF AAG concentration, as well as in AAG quotient and index, appear only after several years of disease duration, while no significant correlation with age has been found. This suggests that CSF AAG changes in MS represent a secondary, unspecific phenomenon and that this protein is not relevant for the aethiopathogenesis of the disease. Nevertheless, the finding of subnormal CSF AAG levels in some MS patients in remission (never observed in those in the attack) implies the possibility that CSF AAG may be used as a "state marker" in MS. Serum AAG levels were significantly lower in secondary progressive form and in severely disabled patients. This observation suggest that serum AAG values determination might have some prognostic significance. Further studies are, however, needed. Serum AAG should be investigated in parallel with other CSF and serum protein fractions in order to establish a pannel of examinations enabling multiple statistical analyses. This approach may lead to the finding of a "complex state marker" enabling thus to evaluate more precisely disease course in individual patients and to accept appropriate therapeutic measures.