We have determined simultaneously the density of beta-adrenoceptors in human myometria (by (-)-[125I]iodopindolol binding) derived from 36 women undergoing cesarean section and in the corresponding circulating lymphocytes (by (-)-[125I]iodocyanopindolol binding). In myometrial membranes about 80% to 85% of the beta-adrenoceptors were of the beta 2-subtype. The density of myometrial and lymphocyte beta-adrenoceptors in women treated with the beta 2-adrenoceptor agonist hexoprenaline to prevent preterm labor was about 65% to 70% lower than that in nontreated women. Concomitantly, in hexoprenaline-treated women the 10 mumol/L isoproterenol-evoked increase in lymphocyte cyclic adenosine monophosphate content (as index for lymphocyte beta-adrenoceptor responsiveness) was diminished to a similar extent. Combining all data resulted in a significant positive correlation between myometrial and lymphocyte beta-adrenoceptor densities (r = 0.7303; n = 36; p less than 0.001). It is possible that determination of beta-adrenoceptor function in circulating lymphocytes may be a useful model to monitor myometrial beta-adrenoceptor changes during tocolytic therapy.
The growth of copper on the hexagonally reconstructed Pt(100) surface has been studied in UHV by scanning tunneling microscopy (STM). The copper film grows anisotropically and initially almost in a bilayer fashion due to a high diffusion barrier at copper island edges and a reduced mobility on the Cu islands. The substrate reconstruction is lifted only locally by Cu island formation. This lifting leads to an ordered incorporation of platinum excess atoms into the first layer of the growing copper film: At 340 K, parallel, monatomically wide platinum chains are formed, whereas at 650 K, broader line structures appear in which the platinum atoms are again hexagonally arranged. Up to nine monolayers, the Cu films remain pseudomorphic with the Pt(100) substrate but undergo an fcc f bct transition beyond 4 monolayers.
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