Caveolin contributes to the modulation of basal and β-adrenoceptor stimulated function of the adult rat ventricular myocyte by simvastatin: A novel pleiotropic effect

The number of people taking statins is increasing across the globe, highlighting the Importance of fully understanding statins effects on the cardiovascular system. The beneficial impact of statins extends well beyond regression of atherosclerosis to include direct effects on tissues of the cardiovascular system (pleiotropic effects). Pleiotropic effects on the cardiac myocyte are often overlooked. Here we consider the contribution of the caveolin protein, whose expression and cellular distribution is dependent on cholesterol, to statin effects on the cardiac myocyte. Caveolin is a structural and regulatory component of caveolae, and is a key regulator of cardiac contractile function and adrenergic responsiveness. We employed an experimental model in which inhibition of myocyte HMG CoA reductase could be studied in the absence of paracrine influences from non-myocyte cells. Adult rat ventricular myocytes were treated with 10 μM simvastatin for 2 days. Simvastatin treatment reduced myocyte cholesterol, caveolin 3 and caveolar density. Negative inotropic and positive lusitropic effects (with corresponding changes in [Ca2]¡) were seen in statin-treated cells. Simvastatin significantly potentiated the inotropic response to β2-, but not β1-, adrenoceptor stimulation. Under conditions of β2-adrenoceptor stimulation, phosphorylation of phospholamban at Ser16and troponin I at Ser23/24was enhanced with statin treatment. Simvastatin increased NO production without significant effects on eNOS expression or phosphorylation (Ser1177), consistent with the reduced expression of caveolin 3, its constitutive Inhibitor. In conclusion, statin treatment can reduce caveolin 3 expression, with functional consequences consistent with the known role of caveolae in the cardiac cell. These data are likely to be of significance, particularly during the early phases of statin treatment, and in patients with heart failure who have altered ß-adrenoceptor signalling. In addition, as caveolin is ubiquitously expressed and has myriad tissue-specific functions, the impact of statin-dependent changes in caveolin is likely to have many other functional sequelae

The 5x1 DAFNE Study Protocol: A cluster randomised trial comparing a standard 5 day DAFNE course delivered over 1 week against DAFNE training delivered over 1 day a week for 5 consecutive weeks.

Background Structured education programmes are now established as an essential component to assist effective self-management of diabetes. In the case of Type 1 diabetes, the Dose Adjustment For Normal Eating (DAFNE) programme improves both glycaemic control and quality of life. Traditionally delivered over five consecutive days, this format has been cited as a barrier to participation by some patients, such as those who work full-time. Some centres in the UK have organised structured education programmes to be delivered one day a week over several consecutive weeks. This type of format may add benefit by allowing more time in which to practice skills between sessions, but may suffer as a result of weaker peer support being generated compared to that formed over five consecutive days. Methods/design We aim to compare DAFNE delivered over five consecutive days (1 week course) with DAFNE delivered one day a week over five weeks (5 week course) in a randomised controlled trial. A total of 213 patients were randomised to attend either a 1 week or a 5 week course delivered in seven participating centres. Study outcomes (measured at baseline, 6 and 12 months post-course) include HbA1c, weight, self-reported rates of severe hypoglycaemia, psychosocial measures of quality of life, and cost-effectiveness. Generalisability was optimised by recruiting patients from DAFNE waiting lists at each centre, and by mailing eligible patients from hospital clinic lists. The inclusion and exclusion criteria were identical to those used to recruit to a standard DAFNE course (e.g., HbA1c <12%, with no lower limit). Qualitative interviews were undertaken with a sub-sample of n=30 patients and their course educators (n=11) to help understand and interpret differences and similarities in outcomes between the two arms, and to identify logistical problems and unanticipated issues arising from the adaptation and delivery of a 5 week course. Discussion This trial has been designed to test the hypothesis that the benefits of delivering a structured education programme over 5 weeks are comparable to those observed after a 1 week course. The results of the trial and the qualitative sub-study will both inform the design and delivery of future DAFNE courses, and the development of structured education programmes in other fields of medicine

A female-emitted pheromone component is associated with reduced male courtship in the parasitoid wasp Spalangia endius

During courtship interactions, the courted individual may not always be prepared to mate. For example, mating or courtship may be detrimental to its fitness and resistance is expected under these circumstances. As such, various resistance strategies have evolved, from physically fending off courting individuals to producing behavioural signals of unreceptivity. In the parasitoid wasp Spalangia endius, females rarely re-mate and mated females are avoided by males in favour of virgin females. Further, mated females appear to advertise their mating status by the release of a pheromone component (methyl 6-methylsalicylate), but direct evidence of the nature of this release is lacking. Here we used real-time chemical analysis to track the emission of the pheromone component during courtship interactions between virgin males and either virgin or mated females. We found that females actively release methyl 6-methylsalicylate when courted and that significantly greater concentrations are released by previously mated females. Further, high concentrations of this component are associated with both the prevention and termination of courtship

Endothelin-1 and isoprenaline co-stimulation causes contractile failure which is partially reversed by MEK inhibition

Objective: The mitogen-activated kinase kinases (MEK)-extracellular signal-regulated kinases (ERK) signaling pathway is activated by agonists like catecholamines or endothelin-1 (ET-1) and has been implicated in cardiac pathology, such as the progression from cardiac hypertrophy to failure. The purpose of the present study, performed in an in vitro model of contractile failure, was to evaluate whether MEK inhibition prevents functional deterioration. Methods and results: Contractile dysfunction was induced in reconstituted rat heart tissue by concomitant treatment with ET-1 (10 nmol/l) and isoprenaline (ISO, 10 nmol/l) for 5 days. While basal force of contraction was unchanged, contractile responsiveness to beta-adrenoceptor agonists was markedly impaired (active force declined to 51% of controls) and was associated with decreased lusitropy. Moreover, in ET-1 + ISO-treated heart tissues, reprogramming of gene expression was observed with an increased ratio of beta-myosin heavy chain (MHC) to alpha-MHC mRNA and increased transcript levels of ANF and skeletal/smooth Muscle alpha-actin isoforms. The MEK inhibitor U0126 (10 mu mol/l) almost completely prevented the reduction in p-adrenergic responsiveness and the negative lusitropic effect of ET-1+ISO co-stimulation. In addition, U0126 completely normalized ANF gene expression, but did not affect or only marginally affected expression of MHC and a-actin isoforms. Conclusions: These results suggest that interruption of the MEK-ERK signaling pathway with a specific MEK inhibitor prevents, in part, the occurrence of a pathologic phenotype secondary to excessive stimulation with neurotulmoral factors. The MEK-ERK pathway seems to be all important but not exclusive regulatory pathway responsible for the development of contractile dysfunction. (c) 2005 European Society of Cardiology. Published by Elsevier B.V All rights reserved

Modeling predictors of changes in glycemic control and diabetes-specific quality of life amongst adults with type 1 diabetes 1 year after structured education in flexible, intensive insulin therapy

Few studies have identified determinants of glycemic control (HbA1c) and diabetes-specific quality of life (DSQoL) in adults with type 1 diabetes. To identify factors predicting outcomes following structured diabetes education. 262 participants completed biomedical and questionnaire assessments before, and throughout 1 year of follow-up. The proportion of variance explained ranged from 28 to 62 % (DSQoLS) and 14–20 % (HbA1c). When change in psychosocial variables were examined, reduced hypoglycemia fear, lower ‘perceived diabetes seriousness’, greater self-efficacy and well-being predicted QoL improvements from baseline to 3-months. Increased frequency of blood glucose testing predicted improvements in HbA1c from baseline to 6-months. Greater benefits may be achieved if programs focus explicitly on psychosocial factors. Self-care behaviours did not predict HbA1c suggesting existing assessment tools need refinement. Evaluation of treatment mechanisms in selfmanagement programs is recommended