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991.
Pulmonary clearance of inhaled 99mTc-DTPA: effects of surfactant depletion by lung lavage 总被引:4,自引:0,他引:4
The influence of surfactant depletion on clearance from the lungs of inhaled technetium-99m-labeled diethylenetriamine pentaacetate (99mTc-DTPA) was studied in rabbits. Surfactant was removed by repeated lung lavage with isotone saline. To minimize structural damage to the lungs, pressure generated insufflation with short expiration was utilized. Aerosolized 99mTc-DTPA was administered via a bag-in-bottle system. Radioactivity was measured with a gamma camera and time-activity curves were obtained over the base of the right lung. Six nonlavaged rabbits served as controls. In six lavaged rabbits clearance of 99mTc-DTPA was significantly faster than in controls. In three rabbits given natural surfactant into the trachea after lung lavage, 99mTc-DTPA was eliminated faster than in controls but slower than in surfactant-depleted animals. The results indicate a role of surfactant on clearance rate of 99mTc-DTPA from rabbit lungs. Measurements of 99mTc-DTPA clearance may be useful in studying the function of the surfactant system in different lung disorders. 相似文献
992.
Psychrolutes marmoratus and Cottunculus granulosus, two psychrolutids, inhabit the shelf and continental slope of the southern South America between 45 and 1,250 m. Over this
range, the P. marmoratus is found in depths of less than 400 m, whilst C. granulosus inhabits waters of >200 m. There is a trend of increasing total length with increasing water depth for P. marmoratus and the converse for C. granulosus. The total lengths of the species are different in the depth zone that they overlap in (200–400 m), and we hypothesise that
this may reduce interspecific competition. Both are specialised carcinophagous feeding on crabs, large isopods and sea spiders,
but they also prey upon polychaets and gastropods. There was no difference in the feeding spectra of similar-sized fish sampled
at the same depth, indicating a similar foraging strategy. In contrast to this, the feeding spectra are quite different between
the species over different depths as well as at different adult sizes. The feeding niche breadth in these species is similar
to other slope dwelling fish in the area. 相似文献
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995.
N.m.r. studies of metabolism in perfused organs 总被引:1,自引:0,他引:1
J J Ackerman P J Bore D G Gadian T H Grove G K Radda 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1980,289(1037):425-436
Several metabolites and intracellular pH in intact organs can be studied in a non-destructive manner by phorphorus nuclear magnetic resonance (31P n.m.r.). This possibility was demonstrated by us nearly five years ago. Since then we have developed the appropriate physiological techniques and improved the n.m.r. method for the study of animal hearts and kidneys. Here we described measurements aimed at clarifying three problesm. (1) Having measured the enzyme-catalysed fluxes between phosphocreatine and ATP by the method of saturation transfer n.m.r., we examine the relations between energy supply and heart rate in the isolated perfused rat heart. (2) We describe experiments to establish the validity of the perfusion model. For the first time, we report 31P n.m.r. measurements of an in vivo rat heart and compare the results with those obtained for the perfused rat heart. (3) Ischaemia and metabolism in rabbit kidneys is investigated to establish the relation between functional and metabolic recovery after a renal transplant operation. 相似文献
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999.
With the view of incorporating quaternary ammonium salts (QAs) in marine paints, nineteen of these were tested against a community of marine bacteria, at a temperature and salinity close to those of seawater. The concentration of QAs and the length of the main substituting chain are the main parameters affecting the growth and adhesion of bacteria, but the nature of (i) the other chains, (ii) the counter‐ion and (iii) the rings when inserted in the QA molecule also influenced the bacteria. Increasing the concentration of the QAs decreased the growth rate of the bacteria, the maximum cell density at the plateau and the rate of adhesion. The effect of increasing the length of the main chain depended on the range of carbon numbers. Below 7 carbon atoms, the growth rate was not significantly modified, but the numbers of cells at the plateau increased in contrast with the adhesion rate which decreased rapidly. Increasing the length of the chain to between 7 and 16 carbon atoms resulted in a decrease in the growth rate, a decrease and then a stabilisation in the numbers of cells at the plateau and no further change in the adhesion rate. Possibly an increase in growth rate, adhesion rate and in the numbers of cells at the plateau may occur above 16 carbon atoms. In contrast, the length of the other chains influenced positively the cell concentration at the plateau, and more generally the efficiency of QAs decreased substantially when these chains had the same numbers of carbon atoms. QAs with iodide as counter‐ion were more effective than those with chloride or bromide and phenyl was more effective than benzyl as rings inserted in QAs. The minimum inhibitory concentrations (MIC) were often very high if compared to standard methods with laboratory strains, and this can be tentatively explained by the dominance of Gram— bacteria in the community assayed, the development of resistant strains in the cultures used with time and the presence of organic matter in the culture medium. 相似文献
1000.
Using affinity capillary electrophoresis to study the interaction of the extracellular binding domain of erythropoietin receptor with peptides. 总被引:1,自引:0,他引:1
G W Caldwell P A McDonnell J A Masucci D L Johnson L K Jolliffe 《Journal of biochemical and biophysical methods》1999,40(1-2):17-25
We have shown that affinity capillary electrophoresis (ACE) can be utilized to screen peptides that bind to the extracellular binding domain of the erythropoietin receptor (EBP). The comparison of the cyclic peptides GGTYSCHFGPLTWVCKPQGG (EMP1) GGTYSCHFGPLTAVCKPQGG (EMP13), and LGRKYSCHFGPLTWVCQPAKKD (EMP37) with the linear peptides HFGPLTWV (EMP26) and FMRF as ACE buffer additives were investigated. When EMP1 and EMP37 were the buffer additives, an abrupt change in the electrophoretic mobility of EBP was observed in the electropherogram. When EMP13, EMP26, and FMRF were examined under identical ACE conditions as EMP1 and EMP37, no significant change in the electrophoretic mobility of EBP was observed. These results correlate well with previously reported IC50 competitive binding data; that is, EMP1 and EMP37 bind to EBP while EMP13 and EMP26 bind very weakly. These observations strongly infer that peptide.EBP dimerization were induced by EMP1, and EMP37 but not by EMP13, EMP26 or FMRF. This ACE method provides a rapid tool for the detection of small peptides or drugs that bind to EBP. 相似文献