Traumatic brain injury and the effects of diazepam, diltiazem, and MK-801 on GABA-A receptor subunit expression in rat hippocampus

<p>Abstract</p> <p>Background</p> <p>Excitatory amino acid release and subsequent biochemical cascades following traumatic brain injury (TBI) have been well documented, especially glutamate-related excitotoxicity. The effects of TBI on the essential functions of inhibitory GABA-A receptors, however, are poorly understood.</p> <p>Methods</p> <p>We used Western blot procedures to test whether <it>in vivo </it>TBI in rat altered the protein expression of hippocampal GABA-A receptor subunits α1, α2, α3, α5, β3, and γ2 at 3 h, 6 h, 24 h, and 7 days post-injuy. We then used pre-injury injections of MK-801 to block calcium influx through the NMDA receptor, diltiazem to block L-type voltage-gated calcium influx, or diazepam to enhance chloride conductance, and re-examined the protein expressions of α1, α2, α3, and γ2, all of which were altered by TBI in the first study and all of which are important constituents in benzodiazepine-sensitive GABA-A receptors.</p> <p>Results</p> <p>Western blot analysis revealed no injury-induced alterations in protein expression for GABA-A receptor α2 or α5 subunits at any time point post-injury. Significant time-dependent changes in α1, α3, β3, and γ2 protein expression. The pattern of alterations to GABA-A subunits was nearly identical after diltiazem and diazepam treatment, and MK-801 normalized expression of all subunits 24 hours post-TBI.</p> <p>Conclusions</p> <p>These studies are the first to demonstrate that GABA-A receptor subunit expression is altered by TBI <it>in vivo</it>, and these alterations may be driven by calcium-mediated cascades in hippocampal neurons. Changes in GABA-A receptors in the hippocampus after TBI may have far-reaching consequences considering their essential importance in maintaining inhibitory balance and their extensive impact on neuronal function.</p

Coherent two-dimensional Fourier transform spectroscopy using a 25 Tesla resistive magnet.

We performed nonlinear optical two-dimensional Fourier transform spectroscopy measurements using an optical resistive high-field magnet on GaAs quantum wells. Magnetic fields up to 25 T can be achieved using the split helix resistive magnet. Two-dimensional spectroscopy measurements based on the coherent four-wave mixing signal require phase stability. Therefore, these measurements are difficult to perform in environments prone to mechanical vibrations. Large resistive magnets use extensive quantities of cooling water, which causes mechanical vibrations, making two-dimensional Fourier transform spectroscopy very challenging. Here, we report on the strategies we used to overcome these challenges and maintain the required phase-stability throughout the measurement. A self-contained portable platform was used to set up the experiments within the time frame provided by a user facility. Furthermore, this platform was floated above the optical table in order to isolate it from vibrations originating from the resistive magnet. Finally, we present two-dimensional Fourier transform spectra obtained from GaAs quantum wells at magnetic fields up to 25 T and demonstrate the utility of this technique in providing important details, which are obscured in one dimensional spectroscopy

Efficacy and safety of cangrelor in patients with peripheral artery disease undergoing percutaneous coronary intervention – Insights from the CHAMPION program

Abstract Background Peripheral artery disease (PAD) is associated with an increased risk of ischemic events following percutaneous coronary intervention (PCI). More aggressive antiplatelet therapy may mitigate this risk. The present study evaluates the efficacy of cangrelor in patients with PAD undergoing PCI. Methods and results This is a pooled analysis from the CHAMPION PCI, CHAMPION PLATFORM, AND CHAMPION PHOENIX trials, evaluating cangrelor versus either clopidogrel or placebo in PCI patients. The occurrence of the primary endpoint of death, myocardial infarction, or ischemia-driven revascularization (IDR) was assessed in patients with and without PAD. GUSTO severe bleeding at 48 h was also evaluated. There were 1720 (7%) patients with PAD and 22,802 (93%) without PAD. After adjustment for differences in baseline variables, PAD patients, compared with those without PAD, experienced increased odds of the primary endpoint (OR [95% CI] = 1.27 [0.91, 1.77], P = 0.16) and GUSTO severe bleeding (OR [95% CI] = 3.24 [1.28, 8.21], P = 0.01). In PAD patients, the primary endpoint was 4.7% with cangrelor vs. 7.2% with clopidogrel (OR [95% CI] = 0.64 [0.42,0.96]); in patients without PAD the primary endpoint was 3.5% with cangrelor vs. 4.2% with clopidogrel (OR [95% CI] = 0.83 [0.72,0.95]), P-interaction 0.23. Among patients with or without PAD, there was no significant difference in the rate of GUSTO severe bleeding with cangrelor compared with control, P-interaction 0.86. Conclusions In a pooled analysis of the CHAMPION studies, PAD was associated with increased rates of ischemic and bleeding complications. Cangrelor reduced the odds of ischemic events, without increasing GUSTO severe bleeding. Clinical trial registration clinicaltrials.gov identifiers: CHAMPION PCI ( NCT00305162 ), CHAMPION PLATFORM ( NCT00385138 ), CHAMPION PHOENIX ( NCT01156571

Consistent Reduction in Periprocedural Myocardial Infarction With Cangrelor as Assessed by Multiple Definitions

BACKGROUND: Cangrelor is an intravenous P2Y12 inhibitor approved to reduce periprocedural ischemic events in patients undergoing percutaneous coronary intervention not pretreated with a P2Y12 inhibitor. METHODS: A total of 11 145 patients were randomized to cangrelor or clopidogrel in the CHAMPION PHOENIX trial (Cangrelor versus Standard Therapy to Achieve Optimal Management of Platelet Inhibition). We explored the effects of cangrelor on myocardial infarction (MI) using different definitions and performed sensitivity analyses on the primary end point of the trial. RESULTS: A total of 462 patients (4.2%) undergoing percutaneous coronary intervention had an MI as defined by the second universal definition. The majority of these MIs (n=433, 93.7%) were type 4a. Treatment with cangrelor reduced the incidence of MI at 48 hours (3.8% versus 4.7%; odds ratio [OR], 0.80; 95% confidence interval [CI], 0.67-0.97; P=0.02). When the Society of Coronary Angiography and Intervention definition of periprocedural MI was applied to potential ischemic events, there were fewer total MIs (n=134); however, the effects of cangrelor on MI remained significant (OR, 0.65; 95% CI, 0.46-0.92; P=0.01). Similar effects were seen in the evaluation of the effects of cangrelor on MIs with peak creatinine kinase-MB ≥10 times the upper limit of normal (OR, 0.64; 95% CI, 0.45-0.91) and those with peak creatinine kinase-MB ≥10 times the upper limit of normal, ischemic symptoms, or ECG changes (OR, 0.63; 95% CI, 0.48-0.84). MIs defined by any of these definitions were associated with increased risk of death at 30 days. Treatment with cangrelor reduced the composite end point of death, MI (Society of Coronary Angiography and Intervention definition), ischemia-driven revascularization, or Academic Research Consortium definite stent thrombosis (1.4% versus 2.1%; OR, 0.69; 95% CI, 0.51-0.92). CONCLUSIONS: MI in patients undergoing percutaneous coronary intervention, regardless of definition, remains associated with increased risk of death in the current era. Cangrelor compared with clopidogrel significantly reduces MI regardless of the definition. CLINICAL TRIAL REGISTRATION: URL: http://clinicaltrials.gov. Unique identifier: NCT01156571

Ticagrelor monotherapy in patients with concomitant diabetes mellitus and chronic kidney disease: a post hoc analysis of the GLOBAL LEADERS trial.

BACKGROUND Patients with both diabetes mellitus (DM) and chronic kidney disease (CKD) are a subpopulation characterized by ultrahigh ischemic and bleeding risk after percutaneous coronary intervention. There are limited data on the impact of ticagrelor monotherapy among these patients. METHODS In this post hoc analysis of the GLOBAL-LEADERS trial, the treatment effects of the experimental (one-month dual-antiplatelet therapy [DAPT] followed by 23-month ticagrelor monotherapy) versus the reference regimen (12-month DAPT followed by 12-month aspirin alone) were analyzed according to DM/CKD status. The primary endpoint was a composite endpoint of all-cause death or new Q-wave myocardial infarction at 2-years. The patient-oriented composite endpoint (POCE) was defined as the composite of all-cause death, any stroke, site-reported MI and any revascularization, whereas net adverse clinical events (NACE) combined POCE with BARC type 3 or 5 bleeding events. RESULTS At 2 years, the DM + /CKD + patients had significantly higher incidences of the primary endpoint (9.5% versus 3.1%, adjusted HR 2.16; 95% CI [1.66-2.80], p < 0.001), BARC type 3 or 5 bleeding events, stroke, site-reported myocardial infraction, all revascularization, POCE, and NACE, compared with the DM-/CKD- patients. Among the DM + /CKD + patients, after adjustment, there were no significant differences in the primary endpoints between the experimental and reference regimen; however, the experimental regimen was associated with lower rates of POCE (20.6% versus 25.9%, HR 0.74; 95% CI [0.55-0.99], p = 0.043, pinteraction = 0.155) and NACE (22.7% versus 28.3%, HR 0.75; 95% CI [0.56-0.99], p = 0.044, pinteraction = 0.310), which was mainly driven by a lower rate of all revascularization, as compared with the reference regimen. The landmark analysis showed that while the experimental and reference regimen had similar rates of all the clinical endpoints during the first year, the experimental regimen was associated with significantly lower rates of POCE (5.8% versus 11.0%, HR 0.49; 95% CI [0.29-0.82], p = 0.007, pinteraction = 0.040) and NACE (5.8% versus 11.2%, HR 0.48; 95% CI [0.29-0.82], p = 0.007, pinteraction = 0.013) in the second year. CONCLUSION Among patients with both DM and CKD, ticagrelor monotherapy was not associated with lower rates of all-cause death or new Q-wave, or major bleeding complications; however, it was associated with lower rates of POCE and NACE. These findings should be interpreted as hypothesis-generating. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov (NCT01813435)

Impact of proton pump inhibitors on efficacy of antiplatelet strategies with ticagrelor or aspirin after percutaneous coronary intervention:Insights from the GLOBAL LEADERS trial

BACKGROUND Several studies have suggested that proton pump inhibitors (PPIs) may reduce the antiplatelet effects of clopidogrel and/or aspirin, possibly leading to cardiovascular events. AIMS We aimed to investigate the association between PPI and clinical outcomes in patients treated with ticagrelor monotherapy or conventional antiplatelet therapy after percutaneous coronary intervention (PCI). METHODS This is a subanalysis of the randomized GLOBAL LEADERS trial, comparing the experimental antiplatelet arm (23-month ticagrelor monotherapy following 1-month dual antiplatelet therapy [DAPT]) with the reference arm (12-month aspirin monotherapy following 12-month DAPT) after PCI. Patient-oriented composite endpoints (POCEs: all-cause mortality, myocardial infarction, stroke, or repeat revascularization) and its components were assessed stratified by PPI use as a time-dependent covariate in patients with the experiment or reference antiplatelet arm. RESULTS Among 15,839 patients, 2115 patients (13.5%) experienced POCE at 2 years. In the reference arm, the use of PPIs was independently associated with POCE (hazard ratio [HR]: 1.27; 95% confidence interval [CI]: 1.12-1.44) and its individual components, whereas it was not in the experimental arm (HR: 1.04; 95% CI: 0.92-1.19; pinteraction  = 0.035). During the second-year follow-up, patients taking aspirin with PPIs had a significantly higher risk of POCE compared to those on aspirin without PPIs (HR: 1.57; 95% CI: 1.27-1.94), whereas the risk did not differ significantly irrespective of PPI in ticagrelor monotherapy group (HR: 1.03; 95% CI: 0.83-1.28; pinteraction  = 0.008). CONCLUSIONS In contrast to conventional antiplatelet strategy, there were no evidence suggesting the interaction between ticagrelor monotherapy and PPIs on increased cardiovascular events, which should be confirmed in further studies. CLINICAL TRIAL REGISTRATION URL: https://clinicaltrials.gov

Prehospital ticagrelor in ST-segment elevation myocardial infarction

Background:The direct-acting platelet P2Y receptor antagonist ticagrelor can reduce the incidence of major adverse cardiovascular events when administered at hospital admission to patients with ST-segment elevation myocardial infarction (STEMI). Whether prehospital administration of ticagrelor can improve coronary reperfusion and the clinical outcome is unknown. Methods: We conducted an international, multicenter, randomized, double-blind study involving 1862 patients with ongoing STEMI of less than 6 hours' duration, comparing prehospital (in the ambulance) versus in-hospital (in the catheterization laboratory) treatment with ticagrelor. The coprimary end points were the proportion of patients who did not have a 70% or greater resolution of ST-segment elevation before percutaneous coronary intervention (PCI) and the proportion of patients who did not have Thrombolysis in Myocardial Infarction flow grade 3 in the infarct-related artery at initial angiography. Secondary end points included the rates of major adverse cardiovascular events and definite stent thrombosis at 30 days. Results: The median time from randomization to angiography was 48 minutes, and the median time difference between the two treatment strategies was 31 minutes. The two coprimary end points did not differ significantly between the prehospital and in-hospital groups. The absence of ST-segment elevation resolution of 70% or greater after PCI (a secondary end point) was reported for 42.5% and 47.5% of the patients, respectively. The rates of major adverse cardiovascular events did not differ significantly between the two study groups. The rates of definite stent thrombosis were lower in the prehospital group than in the in-hospital group (0% vs. 0.8% in the first 24 hours; 0.2% vs. 1.2% at 30 days). Rates of major bleeding events were low and virtually identical in the two groups, regardless of the bleeding definition use