Transcriptional and phenotypic comparisons of Ppara knockout and siRNA knockdown mice

RNA interference (RNAi) has great potential as a tool for studying gene function in mammals. However, the specificity and magnitude of the in vivo response to RNAi remains to be fully characterized. A molecular and phenotypic comparison of a genetic knockout mouse and the corresponding knockdown version would help clarify the utility of the RNAi approach. Here, we used hydrodynamic delivery of small interfering RNA (siRNA) to knockdown peroxisome proliferator activated receptor alpha (Ppara), a gene that is central to the regulation of fatty acid metabolism. We found that Ppara knockdown in the liver results in a transcript profile and metabolic phenotype that is comparable to those of Ppara(−/−) mice. Combining the profiles from mice treated with the PPARα agonist fenofibrate, we confirmed the specificity of the RNAi response and identified candidate genes proximal to PPARα regulation. Ppara knockdown animals developed hypoglycemia and hypertriglyceridemia, phenotypes observed in Ppara(−/−) mice. In contrast to Ppara(−/−) mice, fasting was not required to uncover these phenotypes. Together, these data validate the utility of the RNAi approach and suggest that siRNA can be used as a complement to classical knockout technology in gene function studies

Association of Chromosome 9p21 with Subsequent Coronary Heart Disease events:A GENIUS-CHD study of individual participant data

BACKGROUND:Genetic variation at chromosome 9p21 is a recognized risk factor for coronary heart disease (CHD). However, its effect on disease progression and subsequent events is unclear, raising questions about its value for stratification of residual risk. METHODS:A variant at chromosome 9p21 (rs1333049) was tested for association with subsequent events during follow-up in 103,357 Europeans with established CHD at baseline from the GENIUS-CHD Consortium (73.1% male, mean age 62.9 years). The primary outcome, subsequent CHD death or myocardial infarction (CHD death/MI), occurred in 13,040 of the 93,115 participants with available outcome data. Effect estimates were compared to case/control risk obtained from CARDIoGRAMPlusC4D including 47,222 CHD cases and 122,264 controls free of CHD. RESULTS:Meta-analyses revealed no significant association between chromosome 9p21 and the primary outcome of CHD death/MI among those with established CHD at baseline (GENIUS-CHD OR 1.02; 95% CI 0.99-1.05). This contrasted with a strong association in CARDIoGRAMPlusC4D OR 1.20; 95% CI 1.18-1.22; p for interaction Conclusions: In contrast to studies comparing individuals with CHD to disease free controls, we found no clear association between genetic variation at chromosome 9p21 and risk of subsequent acute CHD events when all individuals had CHD at baseline. However, the association with subsequent revascularization may support the postulated mechanism of chromosome 9p21 for promoting atheroma development

Rapid intravascular injection into limb skeletal muscle: a damage assessment study

We have recently developed a simple and highly efficient methodology for delivering plasmid DNA (pDNA) to skeletal muscle cells of mammalian limbs. The procedure involves the rapid intravascular injection of a large volume of saline (containing pDNA) into the vasculature of the distal limb. As a result of the robust delivery methodology involved, it is important to understand the effects of the injection procedure on the skeletal muscle tissue in the targeted limb. In previous studies, only modest and transient muscle damage was noted. In this study we quantitatively assessed the degree of muscle damage in rat limbs following intravascular injections using muscle histology (H&E staining), membrane integrity (Evans blue staining), and leukocyte infiltration (immunohistochemistry) assays. The rapid extravasation of fluid during the injection process resulted in edema of the muscle tissue of the targeted limb; however, the edema was transient and resolved within 24 h. Consistent with observations from previous studies, minimal levels of myofiber damage were detected. Immunohistochemical labeling indicated that increased numbers of neutrophils (CD43+) and macrophages (ED1+ and ED2+) were present in the muscle tissue interstitium shortly after injection but that elevations were relatively modest and resolved by 2 weeks postinjection

Evaluation of Hydrodynamic Limb Vein Injections in Nonhuman Primates

The group of Dr. Jon A. Wolff reports results from a study examining the effects of a variety of parameters, such as rate and volume of injection, on the efficiency of hydrodynamic limb vein injection mediated gene transfer of luciferase in rats and nonhuman primates

Apixaban Plus Mono Versus Dual Antiplatelet Therapy in Acute Coronary Syndromes: Insights From the APPRAISE-2 Trial

Item does not contain fulltextBACKGROUND: Bleeding limits anticoagulant treatment in patients with acute coronary syndromes (ACS). OBJECTIVES: We investigated whether background concomitant antiplatelet therapy influences the effects of apixaban after ACS. METHODS: This study examined high-risk ACS patients who were treated with aspirin or aspirin plus clopidogrel and who were randomized to apixaban 5 mg twice daily or placebo. In a post-hoc analysis, we assessed whether the effect of apixaban on efficacy and safety outcomes varied by the concomitant antiplatelet regimen by using simple Cox modeling and marginal structural models with propensity scores and antiplatelet therapy as a time-dependent covariate. RESULTS: At baseline, of 7,364 patients, 16.3% (n = 1,202) were on aspirin alone, and 79.0% (n = 5,814) were on aspirin plus clopidogrel. A total of 19.2% (n = 1,415) switched antiplatelet therapy during follow-up. No differential effect of apixaban versus placebo was observed for the composite endpoint of cardiovascular death, myocardial infarction, and ischemic stroke in patients taking aspirin (12.21 per 100 patient-years vs. 13.21 per 100 patient-years; adjusted hazard ratio [HR]: 0.91; 95% confidence interval [CI]: 0.62 to 1.32) or aspirin plus clopidogrel (13.22 vs. 14.24; adjusted HR: 0.95; 95% CI: 0.78 to 1.14; pinteraction = 0.84). Compared with placebo, apixaban increased Thrombolysis In Myocardial Infarction major bleeding in patients taking aspirin (1.48 vs. 0.25; adjusted HR: 6.62; 95% CI: 0.75 to 51.73) and in patients taking aspirin plus clopidogrel (2.58 vs. 1.02; adjusted HR: 2.44; 95% CI: 1.34 to 4.45; pinteraction = 0.41). Similar results were obtained with marginal structural models and in patients treated with and without percutaneous coronary intervention. CONCLUSIONS: Post-ACS treatment with apixaban versus placebo showed no efficacy, but it increased bleeding regardless of concomitant therapy with aspirin alone or aspirin plus clopidogrel. (Apixaban for Prevention of Acute Ischemic Events 2 [APPRAISE-2]; NCT00831441)