Does polarity of A2b adenosine receptor expression determine characteristics of receptor desensitization?
1) a single receptor subtype, here modeled by the A2b receptor, differentially desensitizes based on the membrane domain on which it is expressed, 2) agonist exposure on one domain can result in desensitization of receptors on the opposite domain, 3) cross-domain desensitization can display strict polarity, and 4) receptor trafficking may play a role in the cross-desensitization process.
The value of ultrasound examination before the 10th weeks of pregnancy is not validated when the patient has no complaint even if it appears as the most powerful mean to assess the accurate gestational age and observing fetal cardiac activity is the best prognostic variable for the outcome of the fetus.