Myocardial edema after ischemia/reperfusion is not stable and follows a bimodal pattern: Imaging and histological tissue characterization

It is widely accepted that edema occurs early in the ischemic zone and persists in stable form for at least 1 week after myocardial ischemia/reperfusion. However, there are no longitudinal studies covering from very early (minutes) to late (1 week) reperfusion stages confirming this phenomenon. This study sought to perform a comprehensive longitudinal imaging and histological characterization of the edematous reaction after experimental myocardial ischemia/reperfusion. The study population consisted of 25 instrumented Large-White pigs (30 kg to 40 kg). Closed-chest 40-min ischemia/reperfusion was performed in 20 pigs, which were sacrificed at 120 min (n = 5), 24 h (n = 5), 4 days (n = 5), and 7 days (n = 5) after reperfusion and processed for histological quantification of myocardial water content. Cardiac magnetic resonance (CMR) scans with T2-weighted short-tau inversion recovery and T2-mapping sequences were performed at every follow-up stage until sacrifice. Five additional pigs sacrificed after baseline CMR served as controls. In all pigs, reperfusion was associated with a significant increase in T2 relaxation times in the ischemic region. On 24-h CMR, ischemic myocardium T2 times returned to normal values (similar to those seen pre-infarction). Thereafter, ischemic myocardium-T2 times in CMR performed on days 4 and 7 after reperfusion progressively and systematically increased. On day 7 CMR, T2 relaxation times were as high as those observed at reperfusion. Myocardial water content analysis in the ischemic region showed a parallel bimodal pattern: 2 high water content peaks at reperfusion and at day 7, and a significant decrease at 24 h. Contrary to the accepted view, myocardial edema during the first week after ischemia/reperfusion follows a bimodal pattern. The initial wave appears abruptly upon reperfusion and dissipates at 24 h. Conversely, the deferred wave of edema appears progressively days after ischemia/reperfusion and is maximal around day 7 after reperfusion.

Structural brain connectivity and cognitive ability differences: A multivariate distance matrix regression analysis

Neuroimaging research involves analyses of huge amounts of biological data that might or might not be related with cognition. This relationship is usually approached using univariate methods, and, therefore, correction methods are mandatory for reducing false positives. Nevertheless, the probability of false negatives is also increased. Multivariate frameworks have been proposed for helping to alleviate this balance. Here we apply multivariate distance matrix regression for the simultaneous analysis of biological and cognitive data, namely, structural connections among 82 brain regions and several latent factors estimating cognitive performance. We tested whether cognitive differences predict distances among individuals regarding their connectivity pattern. Beginning with 3,321 connections among regions, the 36 edges better predicted by the individuals' cognitive scores were selected. Cognitive scores were related to connectivity distances in both the full (3,321) and reduced (36) connectivity patterns. The selected edges connect regions distributed across the entire brain and the network defined by these edges supports high-order cognitive processes such as (a) (fluid) executive control, (b) (crystallized) recognition, learning, and language processing, and (c) visuospatial processing. This multivariate study suggests that one widespread, but limited number, of regions in the human brain, supports high-level cognitive ability differences. Hum Brain Mapp, 2016. © 2016 Wiley Periodicals, Inc.