Ductus arteriosus sling: report of a newly recognised anomaly and its surgical correction.

Surgical exploration of a 7-week-old infant with a diagnosis of 'pulmonary artery sling' (left pulmonary artery arising from the right) revealed the true nature of the abnormality to be persistence of the ductus arteriosus which connected the right pulmonary artery to the aortic isthmus. This malformation has not been described previously. It has the same symptomatology as 'pulmonary artery sling' and it may be treated by surgical ligation and division. We suggest the term 'ductus arteriosus sling' to describe this rare congenital anomaly.     

Properties of the cytoplasmic progestin-binding protein in the rabbit uterus

An exchange assay for the measurement of total cytoplasmic progestin binding sites has been developed on rabbit uterine cytosol using the highly potent progestin, R5020 (17,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione) labelled to a high specific activity. This compound has several advantages over progesterone: it is not bound by plasma corticosteroid binding globulin; it has high affinity for the progestin receptor; it binds virtually as fast as progesterone to the receptor, but the complex formed dissociated 8 times slower; its binding is not displaced by more than 2% by compounds devoid of progestational activity (estrogens, testosterone, dexamethasone, aldosterone). Bound endogenous progesterone was exchanged by tritiated R 5020 in a time compatible with receptor stability. At 0 C, total exchange of filled sites occurred in less than 4 h; at this temperature the R 5020-receptor complex was stable for at least 28 h. The conformation of the R 5020-receptor complex was investigated in sucrose density gradients under various experimental conditions. Unlike progesterone, it was possible to detect a 7S peak in uterine cytosol obtained from rabbits injected with a tracer dose of [3H]R 5020 1 h prior to sacrifice.     

The nature of [3H]imipramine binding to synaptosomes

In contrast to serotonin “uptake”, the saturable binding of imipramine to rat brain synaptosomes does not involve an active transport process, since it is independent of time, temperature and Na⁺ K⁺-ATPase. It is moreover unaffected by a high concentration of serotonin. confirming that the “uptake” site for this amine is not implicated. Analysis of the saturation curve for binding of imipramine to intact synaptosomes gives a binding constant of 3.5 ± 1.0 × 10^?5 M. Identical binding characteristics are found with a synaptosomal membrane “ghost” fraction. When the membrane fraction is solubilized in Triton X-100, saturable binding is still observed but the affinity for imipramine decreases while the number of binding sites increases. Diverse psychoactive compounds effectively compete with imipramine for binding to synaptosomal membranes and the order of their activity is correlated with their lipophilicity. It is suggested that these compounds interact with a lipophilic pocket of low affinity and low specificity. If a more specific interaction exists and is associated with inhibition of transmitter amine “uptake” by tricyclic antidepressants, it could be masked by this process.