In vivo expression of P-glycoprotein in isolated rat brain mierovessels is compared with that in vitro in primary cultures of brain endothelial cells. More P-glycoprotein is detected by Western immunoblotting in microvessels than in cultured endothelium. RT-PCR with isnform-specific primers and immunobiotting with a mdrlb-specific antibody reveals only mdrla in vivo but both mdrla and mdrlb in vitro. Thus mdrla decreases whereas mdrlb increases during culture. P-Glycoprotein activity is evident in vitro, with resistance modulators, e.g. verapamil, producing increases in intracenular [3H]vincristine accumulation. Endothelial cells cultured from epididymal fat pad microvaseulature and aorta contain little or no P-glycoprotein. Here, resistance modulators are less effective.

The vapor deposition of many molybdenum-containing films relies on the delivery of volatile compounds with the general bis(tert-butylimido)molybdenum(VI) framework, both in atomic layer deposition and chemical vapor deposition. We have prepared a series of (tBuN)2MoCl2 adducts using neutral N,N’-chelates and investigated their volatility, thermal stability, and decomposition pathways. Volatility has been determined by thermogravimetric analysis, with the 1,4-di-tert-butyl-1,3-diazabutadiene adduct (5) found to be the most volatile (1 Torr of vapor pressure at 135 ºC). Thermal stability was measured primarily using differential scanning calorimetry, and the 1,10-phenanthroline adduct (4) was found to be the most stable, with an onset of decomposition of 303 ºC. We have also investigated molybdenum compounds with other alkyl-substituted imido groups: these compounds all follow a similar decomposition pathway, γ-H activation, with varying reaction barriers. The tert-pentyl, 1-adamantyl, and a cyclic imido (from 2,5-dimethylhexane-2,5-diamine) were systematically studied to probe the kinetics of this pathway. All of these compounds have been fully characterized, including via single-crystal X-ray diffraction, and a total of 19 unique structures are reported.

No abstract

The entry of substrates into, and the export of glururonides from, the lumen of hepatic endoplasmic reticulum (ER) in vitro (sealed microsomes) has been measured using radioactivity-labelled materials and a rapid filtration assay. Analysis of liver microsomes from a jaundiced patient showed the accumulation of bilirubin glucuronides within the lumen of the ER. Further analysis of these hepatic microsomes revealed that newly synthesized 1-naphthol glucuronide could exit from the microsomes whereas bilirubin glucuronide was accumulated within the microsomes. These results suggest the existence of mechanisms for the sorting of small molecules, destined for export through bile canalicular or basolateral plasma membranes, by ER. Furthermore, these sorting processes may be regulated by specific transporters within the ER.