A full-length cDNA was isolated from a rat striatal library by using low-stringency screening with two PCR fragments, one spanning transmembrane domains 3-6 of the mouse 6 opioid receptor and the other unidentified but homologous to the mouse 6 receptor from rat brain. The novel cDNA had a long open reading frame encoding a protein of 380 residues with 59% identity to the mouse 6 receptor and topography consistent with a seven-helix guanine nucleotidebinding protein-coupled receptor. COS-1 cells transfected with the coding region of this clone showed high-affinity binding to ic opioid receptor-selective ligands such as dynorphin A and U-50,488 and also nonselective opioid ligands such as bremazocine, ethylketocyclazocine, and naloxone. Not bound at all (or bound with low affimity) were dynorphin A-(2-13), enantiomers of naloxone and levophanol [i.e., (+)-naloxone and dextrorphan], and selective ,u and 8 opioid receptor ligands. Activation of the expressed receptor by X receptor agonists led to inhibition of cAMP. Finally, in situ hybridization revealed a mRNA distribution in rat brain that corresponded well to the distribution of binding sites labeled with i-selective ligands. These observations indicate that we have cloned a cDNA encoding a rat ic receptor of the wc subtype.

SummaryThe regulators of G protein signaling (RGS) are a family of cellular proteins that play an essential regulatory role in G protein-mediated signal transduction. There are multiple RGS subfamilies consisting of over twenty different RGS proteins. They are basically the guanosine triphosphatase (GTPase)-accelerating proteins that specifically interact with G protein α subunits. RGS proteins display remarkable selectivity and specificity in their regulation of receptors, ion channels, and other G protein-mediated physiological events. The molecular and cellular mechanisms underlying such selectivity are complex and cooperate at many different levels. Recent research data have provided strong evidence that the spatiotemporal-specific expression of RGS proteins and their target components, as well as the specific protein-protein recognition and interaction through their characteristic structural domains and functional motifs, are determinants for RGS selectivity and specificity. Other molecular mechanisms, such as alternative splicing and scaffold proteins, also significantly contribute to RGS selectivity. To pursue a thorough understanding of the mechanisms of RGS selective regulation will be of great significance for the advancement of our knowledge of molecular and cellular signal transduction.

Purpose The purpose of this work is to develop a 3D black-blood imaging method for simultaneously evaluating carotid and intracranial arterial vessel wall with high spatial resolution and excellent blood suppression with and without contrast enhancement. Methods DANTE preparation module was incorporated into SPACE sequence to improve blood signal suppression. Simulations and phantom studies were performed to quantify image contrast variations induced by DANTE. DANTE-SPACE, SPACE and 2D TSE were compared for apparent SNR, CNR and morphometric measurements in fourteen healthy subjects. Preliminary clinical validation was performed in six symptomatic patients. Results Apparent residual luminal blood was observed in 5 (pre-CE) and 9 (post-CE) subjects with SPACE, and only 2 (post-CE) subjects with DANTE-SPACE. DANTE-SPACE showed 31% (pre-CE) and 100% (post-CE) improvement in wall-to-blood CNR over SPACE. Vessel wall area measured from SPACE was significantly larger than that from DANTE-SPACE due to possible residual blood signal contamination. In patients DANTE-SPACE showed the potential to detect vessel wall dissection and identify plaque components. Conclusion DANTE-SPACE significantly improved arterial and venous blood suppression compared with SPACE. Simultaneous high-resolution carotid and intracranial vessel wall imaging to potentially identify plaque components was feasible with scan time under 6 minutes.

No abstract