Alexandros Kokkinos

Time-dependent changes in the expression of thyroid hormone receptor α1 in the myocardium after acute myocardial infarction: possible implications in cardiac remodelling

The present study investigated whether changes in thyroid hormone (TH) signalling can occur after acute myocardial infarction (AMI) with possible physiological consequences on myocardial performance. TH may regulate several genes encoding important structural and regulatory proteins particularly through the TR alpha 1 receptor which is predominant in the myocardium. AMI was induced in rats by ligating the left coronary artery while sham-operated animals served as controls. This resulted in impaired cardiac function in AMI animals after 2 and 13 weeks accompanied by a shift in myosin isoforms expression towards a fetal phenotype in the non-infarcted area. Cardiac hypertrophy was evident in AMI hearts after 13 weeks but not at 2 weeks. This response was associated with a differential pattern of TH changes at 2 and 13 weeks; T(3) and T(4) levels in plasma were not changed at 2 weeks but T(3) was significantly lower and T(4) remained unchanged at 13 weeks. A twofold increase in TR alpha 1 expression was observed after 13 weeks in the non-infarcted area, P<0.05 versus sham operated, while TR alpha 1 expression remained unchanged at 2 weeks. A 2.2-fold decrease in TR beta 1 expression was found in the non-infarcted area at 13 weeks, P<0.05, while no change in TR beta 1 expression was seen at 2 weeks. Parallel studies with neonatal cardiomyocytes showed that phenylephrine (PE) administration resulted in 4.5-fold increase in the expression of TR alpha 1 and 1.6-fold decrease in TR beta 1 expression versus untreated, P<0.05. In conclusion, cardiac dysfunction which occurs at late stages after AMI is associated with increased expression of TR alpha 1 receptor and lower circulating tri-iodothyronine levels. Thus, apo-TR alpha 1 receptor state may prevail contributing to cardiac fetal phenotype. Furthermore, down-regulation of TR beta 1 also contributes to fetal phenotypic changes. alpha1-adrenergic signalling is, at least in part, involved in this response.

Study of Postprandial Lipaemia in Type 2 Diabetes Mellitus: Exenatide versus Liraglutide

Therapeutic approaches based on the actions of the incretin hormone GLP-1 have been widely established in the management of T2DM. Nevertheless, much less research has been aimed at elucidating the role of GLP-1 in lipid metabolism and in particular postprandial dyslipidemia. Exenatide and liraglutide are two GLP-1 receptor agonists which are currently available as subcutaneously administered treatment for T2DM but their chronic effects on postprandial lipaemia have not been well investigated. The aim of this study is to examine the effect of treatment with either liraglutide or exenatide for two weeks on postprandial lipaemia in obese subjects with T2DM. This study was a single-center, two-armed, randomized, controlled 2-week prospective intervention trial in 20 subjects with T2DM. Patients were randomized to receive either liraglutide or exenatide treatment and underwent a standardized meal tolerance test early in the morning after 10 h fast at baseline (visit 1, beginning of treatment) and after a two-week treatment period (visit 2). Exenatide and liraglutide both appear to be equally effective in lowering postprandial lipaemia after the first administration and after a two-week treatment. The mechanisms which lead to this phenomenon, which seem to be independent of gastric emptying, are yet to be studied.

Update on Cardiovascular Effects of Older and Newer Anti-diabetic Medications

It is known that Cardiovascular (CV) disease is the leading cause of morbidity and mortality in individuals with type 2 diabetes. Over the last years, one of the most discussed topics is the CV safety of anti-diabetic medications. Regarding CV safety of older antidiabetic agents the data are less clear and conclusions about their CV safety are mostly based on randomized controlled trials designed to assess their glucose lowering efficacy. In this review, we summarize the current knowledge about the CV safety of older and newer antidiabetic medications. According to the published literature metformin is the first line agent for the treatment of type 2 diabetes and seems to have cardio-protective effects. The choice of the second line agent when metformin monotherapy fails to achieve HbA1c targets is less clear. In the light of the findings of the EMPA-REG OUTCOME trial and the recently published LEADER and SUSTAIN 6 trials, empagliflozin, liraglutide and semaglutide seem reasonable options as second line agents for patients with CV disease. Sulfonylureas on the other hand, with the exception of gliclazide, should be avoided in those patients, although CV safety trials are still lacking. In individuals without CV disease any of the other classes of anti-diabetic medication can be selected on a patient-centered approach. Saxagliptin, alogliptin, sitagliptin and lixisenatide have been evaluated in CV safety trials and have neutral effects on CV outcomes, while pioglitazone may have some CV benefits. Saxagliptin and alogliptin, however, should be avoided in patients with heart failure, while pioglitazone is contraindicated in this population.