Contrast Enhanced Micro-Computed Tomography Resolves the 3-Dimensional Morphology of the Cardiac Conduction System in Mammalian Hearts

The general anatomy of the cardiac conduction system (CCS) has been known for 100 years, but its complex and irregular three-dimensional (3D) geometry is not so well understood. This is largely because the conducting tissue is not distinct from the surrounding tissue by dissection. The best descriptions of its anatomy come from studies based on serial sectioning of samples taken from the appropriate areas of the heart. Low X-ray attenuation has formerly ruled out micro-computed tomography (micro-CT) as a modality to resolve internal structures of soft tissue, but incorporation of iodine, which has a high molecular weight, into those tissues enhances the differential attenuation of X-rays and allows visualisation of fine detail in embryos and skeletal muscle. Here, with the use of a iodine based contrast agent (I2KI), we present contrast enhanced micro-CT images of cardiac tissue from rat and rabbit in which the three major subdivisions of the CCS can be differentiated from the surrounding contractile myocardium and visualised in 3D. Structures identified include the sinoatrial node (SAN) and the atrioventricular conduction axis: the penetrating bundle, His bundle, the bundle branches and the Purkinje network. Although the current findings are consistent with existing anatomical representations, the representations shown here offer superior resolution and are the first 3D representations of the CCS within a single intact mammalian heart

Secretion of Novel SEL1L Endogenous Variants Is Promoted by ER Stress/UPR via Endosomes and Shed Vesicles in Human Cancer Cells

We describe here two novel endogenous variants of the human endoplasmic reticulum (ER) cargo receptor SEL1LA, designated p38 and p28. Biochemical and RNA interference studies in tumorigenic and non-tumorigenic cells indicate that p38 and p28 are N-terminal, ER-anchorless and more stable relative to the canonical transmembrane SEL1LA. P38 is expressed and constitutively secreted, with increase after ER stress, in the KMS11 myeloma line and in the breast cancer lines MCF7 and SKBr3, but not in the non-tumorigenic breast epithelial MCF10A line. P28 is detected only in the poorly differentiated SKBr3 cell line, where it is secreted after ER stress. Consistently with the presence of p38 and p28 in culture media, morphological studies of SKBr3 and KMS11 cells detect N-terminal SEL1L immunolabeling in secretory/degradative compartments and extracellularly-released membrane vesicles. Our findings suggest that the two new SEL1L variants are engaged in endosomal trafficking and secretion via vesicles, which could contribute to relieve ER stress in tumorigenic cells. P38 and p28 could therefore be relevant as diagnostic markers and/or therapeutic targets in cancer

Physical inactivity:A risk factor and target for intervention in renal care

Regular physical activity is associated with an increased quality of life and reduced morbidity and mortality in the general population and in patients with chronic kidney disease (CKD). Physical activity, cardiorespiratory fitness, and muscle mass decrease even in the early stages of CKD, and continue to decrease with disease progression; notably, full recovery is generally not achieved with transplantation. The combined effects of uraemia and physical inactivity drive the loss of muscle mass. Regular physical activity benefits cardiometabolic, neuromuscular and cognitive function across all stages of CKD, and therefore provides an approach to address the multimorbidity of the CKD population. Interestingly, maintenance of muscle health is associated with renoprotective effects. Despite evidence of its benefits, physical activity and exercise management are not routinely addressed in the care of these patients. Although studies defining the optimum frequency, duration and intensity of physical activity are lacking, evidence from related fields can guide practical approaches to the care of patients with renal disease. Optimization of metabolic and nutritional status alongside promotion of physical activity is recommended. Behavioural approaches are now recognized as crucial in helping patients to adopt lifestyle changes and might prove valuable in integrating physical activity into renal care