Effects of remote ischemic preconditioning in high-risk patients undergoing cardiac surgery (Remote IMPACT): a randomized controlled trial

Background:Remote ischemic preconditioning is a simple therapy that may reduce cardiac and kidney injury. We undertook a randomized controlled trial to evaluate the effect of this therapy on markers of heart and kidney injury after cardiac surgery.Methods:Patients at high risk of death within 30 days after cardiac surgery were randomly assigned to undergo remote ischemic preconditioning or a sham procedure after induction of anesthesia. The preconditioning therapy was three 5-minute cycles of thigh ischemia, with 5 minutes of reperfusion between cycles. The sham procedure was identical except that ischemia was not induced. The primary outcome was peak creatine kinase–myocardial band (CK-MB) within 24 hours after surgery (expressed as multiples of the upper limit of normal, with log transformation). The secondary outcome was change in creatinine level within 4 days after surgery (expressed as log-transformed micromoles per litre). Patient-important outcomes were assessed up to 6 months after randomization.Results:We randomly assigned 128 patients to remote ischemic preconditioning and 130 to the sham therapy. There were no significant differences in postoperative CK-MB (absolute mean difference 0.15, 95% confidence interval [CI] −0.07 to 0.36) or creatinine (absolute mean difference 0.06, 95% CI −0.10 to 0.23). Other outcomes did not differ significantly for remote ischemic preconditioning relative to the sham therapy: for myocardial infarction, relative risk (RR) 1.35 (95% CI 0.85 to 2.17); for acute kidney injury, RR 1.10 (95% CI 0.68 to 1.78); for stroke, RR 1.02 (95% CI 0.34 to 3.07); and for death, RR 1.47 (95% CI 0.65 to 3.31).Interpretation:Remote ischemic precnditioning did not reduce myocardial or kidney injury during cardiac surgery. This type of therapy is unlikely to substantially improve patient-important outcomes in cardiac surgery. Trial registration: ClinicalTrials.gov, no. {"type":"clinical-trial","attrs":{"text":"NCT01071265","term_id":"NCT01071265"}}NCT01071265.Each year, 2 million patients worldwide undergo cardiac surgery. For more than 25% of these patients, the surgery is complicated by myocardial infarction (MI) and/or acute kidney injury, both of which are strongly associated with morbidity and mortality.^1–3 Preventing MI and acute kidney injury after cardiac surgery would improve survival.An important cause of MI and acute kidney injury in patients undergoing cardiac surgery is ischemia–reperfusion injury.^4,5 This type of injury begins as ischemia, which is then exacerbated by a systemic inflammatory response upon restoration of organ perfusion.⁶ Remote ischemic preconditioning may mitigate ischemia–reperfusion damage. It is accomplished by inducing, before surgery, brief episodes of ischemia in a limb, which lead to widespread activation of endogenous cellular systems that may protect organs from subsequent severe ischemia and reperfusion.^7–9Small randomized controlled trials evaluating the efficacy of remote ischemic preconditioning have had mixed results.^10–17 Interpretation of their data is difficult because of small sample sizes and heterogeneity in the preconditioning procedures and patient populations (e.g., few trials have evaluated patients at high risk of organ injury and postoperative death). Whether remote ischemic preconditioning effectively mitigates ischemia–reperfusion injury therefore remains uncertain. We undertook the Remote Ischemic Preconditioning in Cardiac Surgery Trial (Remote IMPACT) to determine whether this procedure reduces myocardial and kidney injury. We proposed that a large trial to determine the effect on clinically important outcomes would be worthwhile only if a substantial effect on myocardial or kidney injury, or both, were observed in the current study.     

N-Benzyl-N-(tetrahydro-2H-pyran-4-yl)pyrrolidin-3-amines as selective dual serotonin/noradrenaline reuptake inhibitors

A series of N-benzyl-N-(tetrahydro-2H-pyran-4-yl)pyrrolidin-3-amine monoamine reuptake inhibitors are described. Selective dual 5-HT and NA reuptake inhibition was achieved, and analogues with weak CYP2D6 inhibition, good human in vitro metabolic stability and wide ligand selectivity, such as 12b, were identified.     

6,7-Dihydro-5H-pyrrolo[1,2-a] imidazoles as potent and selective α1A adrenoceptor partial agonists

Novel pyrroloimidazoles have been identified as potent partial agonists of the α_1A adrenergic receptor, with good selectivity over the α_1B, α_1D and α_2A receptor subtypes. Pyrimidine 19 possessed attractive CNS drug-like properties with good membrane permeability and no evidence for P-gp mediated efflux.     

Character distribution maps: a visualization method for comparative cladistics

The rise of computational methods and widespread availability of phylogenetic software packages has resulted in a dramatic increase in the number of phylogenetic analyses published each year. We anticipate that as the number of workers and the number of analyses continues to increase, interest in so‐called ‘meta‐analyses’ that compare not just the resultant trees, but the data themselves, will also increase. Here, we demonstrate a simple method for authors to facilitate such comparisons by visually representing the character data included in their analyses, the Character Distribution Map (CDM).     

The use of flow microfluorimetry in the analysis of the phenotype expression of mouse histocompatibility antigens

Quantitation of the expression of cell surface antigens has hitherto been limited to analysis by either cytotoxicity tests or radioimmune assays (5, 15). We report here the use of a new methodology to analyze and quantitate the expression of mouse histocompabililty antigens (H-2 locus) in hybrid clones and parental cell types. The binding of fluorescein-tagged antibody is measured on a cell-to-cell basis in large viable cell populations using flow microfluorimetric techniques. These techniques have been used to measure hapten and immunoglobulin binding to lymphocyte populations (8, 9, 14). However, this is the first report in which these techniques have been used to examine the expression of the H-2 locus. The advantage of this approach is twofold: first, a large and statistically significant sample population may be analyzed one cell at a time, thus revealing the fine detail of heterogeneity in the expression of the cell surface markers within a population. Second, as has been demonstrated for analysis of specific components of the immune system, this method does permit fluorescence-activated sorting of cell types according to their different surface populations (8, 9, 14).     

Heterogeneity in the rate of benzo[a]pyrene metabolism in single cells: quantitation using flow cytometry

We describe a method for quantitating heterogeneity in the rate of benzo[a]pyrene metabolism in single cells by using flow cytometry. We have used the technique to study the response of Hepa-1c1c7 mouse hepatoma cells to the microsomal enzyme inducer 2,3,7,8-tetrachlorodibenzo-p-dioxin. Cells responded in a relatively homogeneous fashion at different times of induction with a maximally inducing concentration of the inducer. However, the induction response could be heterogeneous at a submaximal inducer concentration. We found even higher heterogeneity of enzyme activity among low-activity variants derived from the Hepa-1c1c7 cell line. When cells of either high or low activity were isolated from such a clonal population, propagated, and reanalyzed, they displayed average enzyme activity and heterogeneity identical to the parental cells; therefore, the heterogeneity represents transient, nonheritable differences between cells within the population.     

Neutral additive genetic variance in a metapopulation

For neutral, additive quantitative characters, the amount of additive genetic variance within and among populations is predictable from Wright's FST, the effective population size and the mutational variance. The structure of quantitative genetic variance in a subdivided metapopulation can be predicted from results from coalescent theory, thereby allowing single-locus results to predict quantitative genetic processes. The expected total amount of additive genetic variance in a metapopulation of diploid individual is given by 2Ne sigma m2 (1 + FST), where FST is Wright's among-population fixation index, Ne is the eigenvalue effective size of the metapopulation, and sigma m2 is the mutational variance. The expected additive genetic variance within populations is given by 2Ne sigma e2(1-FST), and the variance among demes is given by 4FSTNe sigma m2. These results are general with respect to the types of population structure involved. Furthermore, the dimensionless measure of the quantitative genetic variance among populations, QST, is shown to be generally equal to FST for the neutral additive model. Thus, for all population structures, a value of QST greater than FST for neutral loci is evidence for spatially divergent evolution by natural selection.