Purification and characterization of 3':5'-cyclic GMP-dependent protein kinase

Guanosine 3':5'-cyclic monophosphate (cGMP)-dependent protein kinase has been purified to homogeneity from bovine lung by affinity chromatography and characterized. Partially purified protein kinase, specifically activated by low concentrations of cGMP (22 NM), was adsorbed onto 8-(2-aminoethyl)-amino-adenosine 3':5'-cyclic monophosphate-Sepharose. After washing to remove nonspecific proteins, cGMP-dependent protein kinase was specifically eluted by 0.1 mM cGMP. The purified protein contained cGMP-dependent protein kinase and specific cGMP binding activities. Purification of the holoenzyme was possible because subunit dissociation does not occur upon cyclic nucleotide binding. cGMP-dependent protein kinase holoenzyme has an apparent molecular weight of 150,000 as determined by glycerol density gradient sedimentation. On sodium dodecyl sulfate/polyacrylamide gel electrophoresis, a single protein band of 71,000 molecular weight was observed that suggested the holoenzyme is a dimer composed of subunits of identical molecular weight. cGMP-dependent protein kinase required high concentrations of Mg+2 for optimal activity; a heat-stable protein kinase modulator which inhibited adenosine 3':5'-cyclic monophosphate-dependent protein kinase activity had no effect on the activity of purified cGMP-dependent protein kinase.

Monitoring Energy Metabolism with Indirect Calorimetry: Instruments, Interpretation, and Clinical Application

Indirect calorimetry is the best measure to guide calorie administration during nutrition support. This article presents an update of the types of currently available indirect calorimeters and reviews the recent advances that guide the clinical application of indirect calorimetry. The emphasis of this report is placed on issues that the practicing clinician can use to evaluate, interpret, and apply measurements of energy expenditure.

Brain death during pregnancy: tocolytic therapy and aggressive maternal support on behalf of the fetus

We report a case of maternal brain death at 25 weeks gestation in which aggressive maternal hemodynamic, respiratory, and metabolic support and tocolytic drug therapy resulted in prolongation of pregnancy for 25 days. The indication for delivery was torulopsis giabrata amnionitis, which may have occurred due to transmembrane or transplacental route. The baby was treated for fungal sepsis, and did well. Premature labor may occur spontaneously after maternal brain death, and may be precipitated by infection or by maternal drug therapy. The myriad of hemodynamic and endocrine issues associated with maternal brain death complicate the choice of tocolytic drugs, but this case illustrates that uterine activity can be successfully blocked, potentially diminishing risks to the newborn, following the tragedy of maternal brain death during pregnancy.