Cloning and expression of the A 2a adenosine receptor from guinea pig brain

A full-length complementary DNA (cDNA) clone encoding the guinea pig brain A 2 adenosine receptor has been isolated by polymerase chain reaction (PCR) and low-stringency-hybridization screening of a guinea pig brain cDNA library. This cDNA contains a long open reading frame encoding a 409-amino acid-residue protein which is highly homologous to the A 2 adenosine receptors previously cloned from other species. Hydrophobicity analysis of the deduced protein sequence reveals seven hydrophobic regions, characteristic of a member of the G-protein-coupled receptor superfamily. Radioligand binding assay and functional (GTPase and cAMP) assays of the receptor, transiently expressed in mammalian cells, demonstrate typical characteristics of the A 2 type adenosine receptor. The messenger RNA (mRNA) of this A 2 receptor is found in the brain, heart, kidney and spleen. Receptor autoradiography with [ 3 H]CGS21680, a specific A 2 agonist, and in situ hybridization with A 2 cRNA probe in guinea pig brain indicate that the receptor is expressed exclusively in the caudate nucleus. The pharmacological profile and anatomical distribution of this receptor indicate that it is of the A 2a subtype. This work represents the first cloning of an A 2a receptor in a rodent species, offers a complete pharmacological characterization of the receptor and provides an anatomical comparison between binding profile and gene expression of the receptor.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45410/1/11064_2004_Article_BF00971338.pd

Calcification of the heart: mechanisms and therapeutic avenues

IntroductionCoronary artery calcification (CAC) is reflective of atherosclerotic disease and incrementally predictive of future cardiovascular events (CVE), independent of traditional risk factors. Extra coronary calcium such as aortic valve calcification, which can be identified and quantified by computed tomography (CT) imaging, has shown to predict future CVE in both asymptomatic and symptomatic (i.e. stable angina and acute coronary syndrome [ACS]) settings. It has hence been a vital tool in studies involving new therapies for cardiovascular disease. Areas covered: In this review, promising therapies on the horizon are reviewed, along with the role of cardiac CT and coronary calcification in these studies. A Medline search for peer-reviewed publications using keywords related to coronary calcium score, aortic valve calcium, and therapies targeting the same was carried out. Expert commentary: CT scanning provides a distinct means of detecting and quantifying coronary plaque as well as valvular calcification with excellent reproducibility. Based on voluminous data available, the absence of coronary calcium serves as a factor to de-risk patients for cardiovascular risk stratification and management algorithms. Newer therapies have shown to lower progression of coronary calcification, thus being beneficial in slowing progression of atherosclerotic disease. As British Epidemiologist Geoffrey Rose states, the best predictor of a life-threatening disease is the early manifestation of that disease. As CAC represents the early manifestation of atherosclerosis, it is the best-known stratifier of risk today, and its clinical use will continue to rise