Defective NOTCH signaling drives increased vascular smooth muscle cell apoptosis and contractile differentiation in bicuspid aortic valve aortopathy: A review of the evidence and future directions.

Bicuspid aortic valve (BAV) disease remains the most common congenital cardiac disease and is associated with an increased risk of potentially fatal aortopathy including aortic aneurysm and dissection. Mutations in the NOTCH1 gene are one of only a few genetic anomalies identified in BAV disease; however evidence for defective NOTCH signaling, and its involvement in the characteristic histological changes of VSMC apoptosis and differentiation in ascending aortae of BAV patients is lacking. This review scrutinizes the evidence for the interactions of NOTCH signaling, cellular differentiation and apoptosis in the context of aortic VSMCs and provides focus for future research efforts in the diagnosis of BAV aortopathy and prevention of catastrophic complications through NOTCH signaling manipulation.

Epithelial-derived IL-18 regulates Th17 cell differentiation and Foxp3⁺ Treg cell function in the intestine.

Elevated levels of interleukin-18 (IL-18) are found in many chronic inflammatory disorders, including inflammatory bowel disease (IBD), and polymorphisms in the IL18R1-IL18RAP locus are associated with IBD susceptibility. IL-18 is an IL-1 family cytokine that has been proposed to promote barrier function in the intestine, but the effects of IL-18 on intestinal CD4(+) T cells are poorly understood. Here we demonstrate that IL-18R1 expression is enhanced on both effector and regulatory CD4(+) T cells in the intestinal lamina propria, with T helper type 17 (Th17) cells exhibiting particularly high levels. We further show that, during steady state, intestinal epithelial cells constitutively secrete IL-18 that acts directly on IL-18R1-expressing CD4(+) T cells to limit colonic Th17 cell differentiation, in part by antagonizing IL-1R1 signaling. In addition, although IL-18R1 is not required for colonic Foxp3(+) regulatory T (Treg) cell differentiation, we found that IL-18R1 signaling was critical for Foxp3(+) Treg cell-mediated control of intestinal inflammation, where it promoted the expression of key Treg effector molecules. Thus IL-18 is a key epithelial-derived cytokine that differentially regulates distinct subsets of intestinal CD4(+) T cells during both homeostatic and inflammatory conditions, a finding with potential implications for treatment of chronic inflammatory disorders.

An observational study of intraoperative transfusion management in a cardiac surgical unit in Trinidad and Tobago.

OBJECTIVE: To investigate the intraoperative transfusion requirements in off-pump coronary artery bypass grafting (OPCABG) and the cost implication of blood products and cell savers on a background of limited resources. METHODS: Prospective data collection identified 60 patients undergoing OPCABG surgery at the Eric Williams Medical Sciences Complex, Trinidad and Tobago. Data relating to these patients (including preoperative haemoglobin (Hb), graft number, presence of diabetes, ejection fraction, preoperative serum creatinine, intraoperative blood use and blood loss) and costing for cell saver disposables and prepared donor (or allogenic) blood were obtained. RESULTS: Twenty units of packed red blood cells (pRBCs) were given in theatre to 27% (16 of 60) of patients. Transfusion requirement was significantly lower in patients with fewer grafts, higher preoperative Hb level and non-diabetic patients. Cell saver disposables and one unit of pRBCs were estimated to cost TT$5000 and TT$1700, respectively. Each patient's transfusion cost TT$2125.00 per unit. CONCLUSION: The study demonstrates the financial implications of routine cell saver use in OPCABG in a setting of limited resources. The cost-effectiveness of routine cell saver use remains to be elucidated, but we recommend the selective use of cell savers in patients who are at a higher risk for transfusion.

Spontaneous frequency of rabbit atrioventricular node myocytes depends on SR function.

Spontaneous Ca(2+) release from the sarcoplasmic reticulum (SR) appears to play an important role in cardiac sinoatrial node pacemaking. However, comparatively little is known about the role of intracellular Ca(2+) in the atrioventricular node (AVN). Intracellular Ca(2+) was therefore monitored in cells isolated from the rabbit AVN, using fluo-3 in conjunction with confocal microscopy. These cells displayed spontaneous Ca(2+) transients and action potentials. Ca(2+) transients were normally preceded by a small, slow increase (ramp) of intracellular Ca(2+) which was sometimes, but not always, accompanied by Ca(2+) sparks. During the Ca(2+) transient, intracellular [Ca(2+)] increased initially at the cell periphery and propagated inhomogeneously to the cell centre. The rate of spontaneous activity was decreased by ryanodine (1muM) and increased by isoprenaline (500nM); these changes were accompanied by a decrease and increase, respectively, in the slope of the preceding Ca(2+) ramp, with no significant change in Ca(2+) spark characteristics. Rapidly reducing bathing [Na(+)] inhibited spontaneous activity. These findings provide the first information on Ca(2+) handling at the sub-cellular level and link cellular Ca(2+) cycling to the genesis of spontaneous activity in the AVN.