Massive Accumulation of Myofibroblasts in the Critical Isthmus Is Associated With Ventricular Tachycardia Inducibility in Post-Infarct Swine Heart

Objectives In this study the authors determined the extent of cellular infiltration and dispersion, and regional vascularization in electrophysiologically (EP) defined zones in post–myocardial infarction (MI) swine ventricle. Background The critical isthmus (CI) in post-MI re-entrant ventricular tachycardia (VT) is a target for catheter ablation. In vitro evidence suggests that myofibroblasts (MFB) within the scar border zone (BZ) may increase the susceptibility to slow conduction and VT, but whether this occurs in vivo remains unproven. Methods Six weeks after mid–left anterior descending coronary artery occlusion, EP catheter-based mapping was used to assess susceptibility to VT induction. EP data were correlated with detailed cellular profiling of ventricular zones using immunohistochemistry and spatial distribution analysis of cardiomyocytes, fibroblasts, MFB, and vascularization. Results In pigs with induced sustained monomorphic VT (mean cycle length: 353 ± 89 ms; n = 6) the area of scar that consisted of the BZ (i.e., between the normal and the low-voltage area identified by substrate mapping) was greater in VT-inducible hearts (iVT) than in noninducible hearts (non-VT) (p 100 times that in normal myocardium and >5 times higher than that in the BZ in non-VT hearts) and by a 1.7-fold increase in blood vessel density within the dense scar region extending towards the CI. Sites of local abnormal ventricular activity potentials exhibited cellularity and vascularization that were intermediate to the CI in iVT and BZ in non-VT hearts. Conclusions The authors reported the first cellular analysis of the VT CI following an EP-based zonal analysis of iVT and non-VT hearts in pigs post-MI. The data suggested that VT susceptibility was defined by a remarkable number of MFB in the VT CI, which appeared to bridge the few remaining dispersed clusters of cardiomyocytes. These findings define the cellular substrate for the proarrhythmic slow conduction pathway

A compatible interaction of Alternaria brassicicola with Arabidopsis thaliana ecotype DiG: evidence for a specific transcriptional signature

<p>Abstract</p> <p>Background</p> <p>The interaction of <it>Arabidopsis </it>with <it>Alternaria brassicicola </it>provides a model for disease caused by necrotrophs, but a drawback has been the lack of a compatible pathosystem. Infection of most ecotypes, including the widely-studied line Col-0, with this pathogen generally leads to a lesion that does not expand beyond the inoculated area. This study examines an ecotype, Dijon G (DiG), which is considered sensitive to <it>A. brassicicola</it>.</p> <p>Results</p> <p>We show that the interaction has the characteristics of a compatible one, with expanding rather than limited lesions. To ask whether DiG is merely more sensitive to the pathogen or, rather, interacts in distinct manner, we identified genes whose regulation differs between Col-0 and DiG challenged with <it>A. brassicicola</it>. Suppression subtractive hybridization was used to identify differentially expressed genes, and their expression was verified using semi-quantitative PCR. We also tested a set of known defense-related genes for differential regulation in the two plant-pathogen interactions. Several known pathogenesis-related (<it>PR</it>) genes are up-regulated in both interactions. <it>PR1</it>, and a monooxygenase gene identified in this study, <it>MO1</it>, are preferentially up-regulated in the compatible interaction. In contrast, <it>GLIP1</it>, which encodes a secreted lipase, and <it>DIOX1</it>, a pathogen-response related dioxygenase, are preferentially up-regulated in the incompatible interaction.</p> <p>Conclusion</p> <p>The results show that DiG is not only more susceptible, but demonstrate that its interaction with <it>A. brassicicola </it>has a specific transcriptional signature.</p

Nucleoplasty – General Overview

The management of disc protrusion is multidisciplinary. In the midway between conservative treatment and open surgery are minimal invasive procedures.Nucleoplasty is a new treatment of discogenic leg pain using bipolar radiofrequency device for vaporising a small volume of nucleus pulposus. Percutaneous removal of nuclear tissue is thought to lower nuclear pressure, thereby reducing nerve root tension and allowing retraction of the protrusion.Causes of discogenic pain are discussed. Indications of the procedure and surgical technique and the literature results are presented