The effects on increasing cardiac output with adrenaline or isoprenaline on arterial haemoglobin oxygen saturation and shunt during one-lung ventilation

Publisher's copy made available with the permission of the publisher © 2000 Australian Society of AnaesthetistsTheoretically, if the cardiac output were increased in the presence of a given intrapulmonary shunt, the arterial haemoglobin oxygen saturation (SaO2) should improve as the venous oxygen extraction per ml of blood decreases. To test this hypothesis, eight pigs were subjected to one-lung ventilation and adrenaline and isoprenaline infusions used to increase the cardiac output. The mixed venous oxygen, shunt fraction and oxygen consumption were measured. With both adrenaline and isoprenaline, although there was a small rise in mixed venous oxygen content, there was a fall in SaO2. With adrenaline, the mean shunt rose from 48% to 65%, the mean oxygen consumption rose from 126 ml/min to 134 ml/min and the mean SaO2 fell from 86.9% to 82.5%. With isoprenaline, the mean shunt rose from 45% to 59%, the mean oxygen consumption rose from 121 ml/min to 137 ml/min and the mean SaO2 fell from 89.5% to 84.7%. It is concluded that potential improvement in SaO2, which might occur from a catecholamine-induced increase in mixed venous oxygen content during one-lung ventilation, is more than offset by increased shunting and oxygen consumption which reduce SaO2.W.J. Russell, M.F. Jameshttp://www.aaic.net.au/Article.asp?D=200010

Reaction Front in an A+B -> C Reaction-Subdiffusion Process

We study the reaction front for the process A+B -> C in which the reagents move subdiffusively. Our theoretical description is based on a fractional reaction-subdiffusion equation in which both the motion and the reaction terms are affected by the subdiffusive character of the process. We design numerical simulations to check our theoretical results, describing the simulations in some detail because the rules necessarily differ in important respects from those used in diffusive processes. Comparisons between theory and simulations are on the whole favorable, with the most difficult quantities to capture being those that involve very small numbers of particles. In particular, we analyze the total number of product particles, the width of the depletion zone, the production profile of product and its width, as well as the reactant concentrations at the center of the reaction zone, all as a function of time. We also analyze the shape of the product profile as a function of time, in particular its unusual behavior at the center of the reaction zone

The Gup1 homologue of Trypanosoma brucei is a GPI glycosylphosphatidylinositol remodelase

Glycosylphosphatidylinositol (GPI) lipids of Trypanosoma brucei undergo lipid remodelling, whereby longer fatty acids on the glycerol are replaced by myristate (C14:0). A similar process occurs on GPI proteins of Saccharomyces cerevisiae where Per1p first deacylates, Gup1p subsequently reacylates the anchor lipid, thus replacing a shorter fatty acid by C26:0. Heterologous expression of the GUP1 homologue of T. brucei in gup1Delta yeast cells partially normalizes the gup1Delta phenotype and restores the transfer of labelled fatty acids from Coenzyme A to lyso-GPI proteins in a newly developed microsomal assay. In this assay, the Gup1p from T. brucei (tbGup1p) strongly prefers C14:0 and C12:0 over C16:0 and C18:0, whereas yeast Gup1p strongly prefers C16:0 and C18:0. This acyl specificity of tbGup1p closely matches the reported specificity of the reacylation of free lyso-GPI lipids in microsomes of T. brucei. Depletion of tbGup1p in trypanosomes by RNAi drastically reduces the rate of myristate incorporation into the sn-2 position of lyso-GPI lipids. Thus, tbGup1p is involved in the addition of myristate to sn-2 during GPI remodelling in T. brucei and can account for the fatty acid specificity of this process. tbGup1p can act on GPI proteins as well as on GPI lipids

Vadose zone measurement and modeling Mensurações e modelagem na zona não saturada

The following treatise is a summary of some of the ongoing research activities in the soil physics program at the University of California in Davis. Each of the four listed areas win be presented at the Workshop on special topics on soil physics and crop modeling in Piracicaba at the University of Sao Paulo. We limited ourselves to a general overview of each area, but will present a more thorough discussion with examples at the Workshop.<br>O presente texto é o resumo das atuais atividades do programa de física do solo na Universidade da Califórnia, em Davis. As quatro áreas aqui relacionadas serão apresentadas no "Workshop on special topics about soil physics and crop modeling and simulation" na Universidade de São Paulo, em Piracicaba. O texto se restringe a urna abordagem geral de cada área, porém discussões e exemplos mais detalhados serão apresentados no Workshop