Omega 3 Fatty Acid Inhibition of Inflammatory Cytokine-Mediated Connexin43 Regulation in the Heart

Background: The proinflammatory cytokine $Interleukin-1\beta$ $(IL-1\beta)$, which increases in the heart post myocardial infarction (MI), has been shown to cause loss of Connexin43 (Cx43) function, an event known to underlie formation of the arrhythmogenic substrate. Omega 3 Fatty acids exhibit antiarrhythmic properties and impact $IL-1\beta$ signaling. We hypothesize that Omega-3 fatty acids prevent arrhythmias in part, by inhibiting $IL-1\beta$ signaling thus maintaining functional Cx43 channels. Methods: Rat neonatal myocytes or Madin-Darby Canine Kidney Epithelial (MDCK) cells grown in media in the absence (Ctr) or presence of $30 \mu M$ docosahexaenoic acid (DHA, an Omega-3 Fatty acid) were treated with $0.1 \mu M$ activated $IL-1\beta$. We determined Cx43 channel function using a dye spread assay. Western blot and immunostaining were used to examine Cx43 levels/localization and downstream effectors of $IL-1\beta$. In addition we used a murine model of MI for 24 h to determine the impact of an Omega-3 fatty acid enriched diet on Cx43 levels/localization post MI. Results: $IL-1\beta$ significantly inhibited Cx43 function in Ctr cells $(200.9 \pm 17.7 \mu m [Ctr] vs. 112.8 \pm 14.9 \mu m [0.1 \mu M IL-1\beta], p<0.05)$. However, DHA-treated cells remained highly coupled in the presence of $IL-1\beta$ $[167.9 \pm 21.9 \mu m [DHA] vs. 164.4 \pm 22.3 \mu m [DHA + 0.1 \ muM IL-1\beta], p<0.05, n = 4]$. Additionally, western blot showed that $IL-1\beta$ treatment caused a 38.5% downregulation of Cx43 $[1.00 au [Ctr] vs. 0.615 au (0.1 \mu M IL-1\beta)$ which was completely abolished in DHA-treated cells $(0.935 au [DHA] vs. 1.02 au [DHA + 0.1 \mu M IL-1\beta), p < 0.05, n = 3]$. Examination of the downstream modulator of $IL-1\beta$, $NF\kappa \beta$ showed that while hypoxia caused translocation of $NF\kappa \beta$ to the nucleus, this was inhibited by DHA. Additionally we found that a diet enriched in Omega-3 Fatty acids inhibited lateralization of Cx43 in the post-MI murine heart as well as limited activation of fibroblasts which would lead to decreased fibrosis overall. Conclusions: Omega 3 Fatty acid treatment inhibited $IL-1\beta$-stimulated loss of Cx43 protein, and more importantly, inhibited loss of Cx43 function by inhibiting translocation of $NF\kappa \beta$. In the intact heart a diet enriched in Omega 3 Fatty Acids limited loss of Cx43 at the intercalated disk in the heart following MI. These data suggest that one of cardio-protective mechanisms by which Omega 3 Fatty acids work includes prevention of the pro-arrhythmic loss of Cx43 post MI and the attenuation of cardiac fibrosis after injury

Increased Cell–Cell Coupling Increases Infarct Size and Does not Decrease Incidence of Ventricular Tachycardia in Mice

Increasing connexin43 (Cx43) gap junctional conductance as a means to improve cardiac conduction has been proposed as a novel antiarrhythmic modality. Yet, transmission of molecules via gap junctions may be associated with increased infarct size. To determine whether maintaining open gap junction channels impacts on infarct size and induction of ventricular tachycardia (VT) following coronary occlusion, we expressed the pH- and voltage-independent connexin isoform connexin32 (Cx32) in ventricle and confirmed Cx32 expression. Wild-type (WT) mice injected with adenovirus-Cx32 (Cx32inj) were examined following coronary occlusion to determine infarct size and inducibility of VT. There was an increased infarct size in Cx32inj hearts as compared to WT (WT 22.9 ± 4%; Cx32inj 44.3 ± 5%; p < 0.05). Programmed electrical stimulation showed no difference in VT inducibility in WT and Cx32inj mice (VT was reproducibly inducible in 55% of shams and 50% of Cx32inj mice (p > 0.05). Following coronary occlusion, improving cell–cell communication increased infarct size, and conferred no antiarrhythmic benefit

Lithological markers of protobazhenit mats splitting on sedimentary slope

Bazhenov abnormal sequences (BAS) are treated as result of protobazhenit plastic deformation by neocomian submarine slump on sedimentary slope. Protobazhenit mats had low bulk density (1.1-1.5 g/sm3) and positive buoyancy in silty-sandy mud of unconsolidated deposits (bulk density 1.7-1.8 g/sm3). Conceptual geomechanical model of BAS generation includes 6 studies: 1 - bedding (slipping) slide, breakage of under-achimovsky clay and protobazhenit, 2 - out-flow achimovsky sandy slump, 3 - slump pulp spreading under protobazhenit layer with its deformation and cracking, 4 - protobazhenit layer cracking due to local loading of growing sedimentary slope, 5 - secondary heaving sand injection through lateral protobazhenit brake side, 6 - burial stage. Up-floating of protobazhenit mats on semiliquid sedimentary slope occurred discretely with numerous subsidings, splittings and jumpings events. During sedimentary slope progradation mats had lack of Archimedes stability due to rising of sedimentary level, led to increment of hydraulic pressure on their side surfaces. The hydraulic fracturing conditions appeared when this pressure exceeded protobazhenit shear strength. Fracturing event was provoked by microseism or by hydraulic shock of gravity mass movement. Mat usually had splitted on two parts: lower part was fixed within sediments, upper one lifted to Archimedes equilibrium level. Splitting and up-lifting of mat produced debris flows, those were spreading on slope and enriched by protobazhenit’sinclasts. These outstanding debrit layers with bazhenitinclasts may be used as lithological markers of mats splitting events for achimovsky sequences. Theoretical model is illustrated by seismostratigraphic interpretation of achimovsky beds of Imilorskoe field of West Siberia. Two types of debrit layers with bazhenitinclasts was detected in well core. First type is generated byptotobazhenit layer’s breakage by non-uniform load of sedimentary slope (fixed in one well). The second type is associated with on-slope splitting and up-lifting of protobazhenit mats (traced in core of three wells)

Gene expression and genetic variation in human atria

BACKGROUND: The human left and right atria have different susceptibilities to develop atrial fibrillation (AF). However, the molecular events related to structural and functional changes that enhance AF susceptibility are still poorly understood. OBJECTIVE: The purpose of this study was to characterize gene expression and genetic variation in human atria. METHODS: We studied the gene expression profiles and genetic variations in 53 left atrial and 52 right atrial tissue samples collected from the Myocardial Applied Genomics Network (MAGNet) repository. The tissues were collected from heart failure patients undergoing transplantation and from unused organ donor hearts with normal ventricular function. Gene expression was profiled using the Affymetrix GeneChip Human Genome U133A Array. Genetic variation was profiled using the Affymetrix Genome-Wide Human SNP Array 6.0. RESULTS: We found that 109 genes were differentially expressed between left and right atrial tissues. A total of 187 and 259 significant cis-associations between transcript levels and genetic variants were identified in left and right atrial tissues, respectively. We also found that a single nucleotide polymorphism at a known AF locus, rs3740293, was associated with the expression of MYOZ1 in both left and right atrial tissues. CONCLUSION: We found a distinct transcriptional profile between the right and left atrium and extensive cis-associations between atrial transcripts and common genetic variants. Our results implicate MYOZ1 as the causative gene at the chromosome 10q22 locus for A