The biochemical maturation of the lung in late gestation and in the young animal is regulated by glucocorticoids. The present study was aimed at dissociating the different glucocorticoid receptor sites involved in these regulatory functions. The obese Zucker rat was selected as a model for this study as it exhibits hypersensitivity to glucocorticoid hormone action by virtue of its elevated receptor numbers and activity. Two synthetic steroid analogues were administered to obese animals; RU28362, a specific type II receptor agonist, and the type II antagonist RU486. RU28362 promoted a strong catabolic effect, which was associated with reduced food intake and the abolition of growth in the rats. The agonist, RU28362, attenuated developmental increases in antioxidant enzyme activities, and altered the growth of the tissue. At the age studied, development of the lung phosphatidylcholine (PC) system was almost complete, but RU28362 increased disaturated PC 16:0/16:0 concentrations by almost 2-fold, and altered the molecular composition of total pulmonary PC. RU486 attenuated the growth of the rats and reduced their food intake. Treatment with the type II antagonist attenuated lung growth and increased the activities of pulmonary copper zinc (Cu/Zn) and manganese (Mn) superoxide dismutases. RU486 had no effect on lung PC concentrations and molecular composition. The data suggest a role for type I glucocorticoid receptors in the regulation of the antioxidant enzyme system in the lung, as type II antagonism will channel endogenous glucocorticoid binding to the type I site. Type II receptor binding would appear to play a role in regulating the lung PC content. 相似文献
A competitive enzyme-linked immunoadsorbent assay (ELISA) technique has been developed to facilitate quantitative analysis of the earliest step in the initiation of the extrinsic pathway of coagulation, i.e., complex formation of factor VII/VIIa with tissue factor. The ELISA measures the binding of biotinylated human plasma factor VII to relipidated recombinant human tissue factor. Quantitation of the relative affinity (expressed as IC50) of any factor VII molecular population or structural analogue for tissue factor can be determined by competitive binding. Subnanomolar concentrations of both wild-type recombinant human factor VII (rFVII) and rFVII(R152Q), a mutation at the FVII activation site, competed effectively with biotinylated plasma-derived factor VII in binding to tissue factor. In contrast, the affinity of rFVII(R79Q), a mutation in the first epidermal growth factor-like domain, was 12-fold lower. Following activation of rFVII(R79Q), its affinity for tissue factor and enzymatic activity increased 4-fold and 6-fold, respectively. For wild-type rFVII, enzymatic activity rose significantly following activation. However, its affinity for tissue factor was unchanged. We conclude that both the activation state of factor VII and the mutation of amino-acid residues within the first epidermal growth factor-like domain may alter the affinity of factor VII for tissue factor. 相似文献
This study examines the extent to which variations in consumers' sensory assessments of food arise from the inability to report accurately sensory perceptions, from confusion regarding the criteria by which to assess samples, or from differences in their oral breakdown of the products.
Twenty consumers assessed the tenderness of a range of 8 hot, freshly roasted meat samples using Time Intensity (TI). Overall a significant correlation was found between the maximum recorded intensity (Imax) of their TI curves and single sensory scores given by a trained panel. Correlation was significant for only 42% of the consumers individually. Significant correlations were found between the amount of masticatory muscle activity undertaken during chewing (measured using electromyography) and Imax for all but 2 of the consumers. Thus subjects' perceptions were accurately described by their chewing work, suggesting between subject differences in perception arose from differences in the way chewing work was applied to break down the samples. The sensory input from the masticatory muscles may represent the major determinant of perceived tenderness of meat. 相似文献
The experiments reported here were designed to test the suggestion of many researchers that selective attention to visual features of a prey can account for search-image effects. In 3 experiments pigeons ate wheat and vetch grains presented on multicolored and gray gravel trays. In Experiment 1 search-image effects were evident when grains were cryptic but not when they were conspicuous. Experiment 2 demonstrated that search images can be activated when the grains encountered are either cryptic or conspicuous but that search images affect search performance only when the grains are cryptic. Experiment 3 demonstrated that search images are short-term in nature: A 3-min delay between successive encounters with a type of grain disrupted an activated search image. The discussion addresses how these results further develop a model in which search images are viewed as selective attention to visual features of a prey. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
In this paper we use data derived from interviews with 215 female homicide offenders incarcerated or on parole in New York to examine their drug use prior to and at the time of the homicide, their victims' drug use, and their perceptions as to the drug-relatedness of the homicides. We found that about 7 out of 10 respondents had been regular users of some drug at some point in their lives prior to their incarceration, while over half had been addicted to a substance. Over one-third of the respondents who were present at the scene were "high" on a drug at the time, while about half of the victims of these homicides used drugs before the homicide. Almost two-thirds of the homicides committed by respondents who were present at the scene were perceived to be drug-related. Alcohol, crack, and powdered cocaine were the drugs most likely to be related to these homicides. The implications of our findings are discussed. 相似文献
A compact multiband planar inverted-F antenna (PIFA) suitable for distributed radio-over-fiber repeater networks is modified into a planar structure. It is shown that the planar antenna performance is not degraded with respect to the original PIFA and further, a two layer design is demonstrated to offer improved feed matching. The European bands for GSM, DCS-1800, DECT, UMTS, Bluetooth and HiperLAN2 are all covered. A model of the antenna is introduced as a first stage to developing an equivalent circuit. 相似文献
Adequate moisture is very important during early age of portland cement concrete. The Single Point Magnetic Resonance Imaging technique was used to study the effects of various lengths of moist curing, and the use of curing compound, on the amount and distribution of evaporable water during drying of ordinary and high performance concrete. The specimens subjected to six different curing regimes, were cast in triplicate for a total of 72. After moist curing at 38°C, the specimens were subjected to uniaxial drying in an environmental chamber at 38°C and 40% relative humidity that simulated hot dry climate conditions. As the specimens were drying, Magnetic Resonance Imaging was used to study the evaporable water distribution, non-destructively and with millimetric resolution. The Magnetic Resonance Imaging profiles indicated a reduced moisture loss with increasing length of moist curing. Extended moist curing was especially beneficial for the two self-compacting concrete mixtures, particularly for the cover concrete. In all mixtures the use of curing compound was only marginally better than one day moist curing, but was significantly better than air curing, particularly for the cover concrete. The moisture diffusivity was evaluated from the transient moisture distribution profiles using the Boltzmann transformation method. The results indicated a strong dependence of the moisture diffusivity on the moisture content when above 80% saturation, whereas below this value it remains almost constant. The moisture diffusivity is significantly reduced with increased moist curing period. 相似文献
A series of first generation dendrimers provide important insight into the performance of dye-sensitised solar cells (DSSCs). The dendrimers are comprised of a substituted [cis-di(thiocyanato)-bis(2,2′-bipyridyl)ruthenium(II) complex, first generation biphenyl-based dendrons, and either four, eight, or twelve 2-ethylhexyloxy surface groups. The dendrimers were bound to the titanium dioxide of the DSSCs via carboxylate groups on one of the bipyridyl moieties in a similar manner to the ‘gold standard’ [cis-di(thiocyanato)-bis(4,4′-dicarboxylate-2,2′-bipyridyl)]ruthenium(II) 1 (N3). Exchanging one pair of the carboxylate groups on one bipyridyl ligand of N3 with styryl units to give [cis-di(thiocyanato)-(4,4′-dicarboxylate-2,2′-bipyridyl)-(4,4′-distyryl-2,2′-bipyridyl]ruthenium(II) 2 resulted in an improvement in device performance (7.19% ± 0.11% for 2 versus 6.94% ± 0.12% for N3). Devices containing the dendrimers also had good efficiencies but the performance was found to decrease with the increasing number of surface groups, which gives rise to an increase in the molecular volume of the dye. The device containing the dendrimer with four surface groups, 3, had a global efficiency of 6.32% ± 0.13%, which was comparable to N3 (6.94% ± 0.12%) in the same device configuration. In contrast, the dendrimer with twelve surface groups, 5, had an efficiency of 3.69% ± 0.19%. Complex 2 and all three dendrimers have the same core chromophore, which absorbs more light than N3. The decrease in efficiency with increasing molecular volume was therefore determined to be due to less dye being adsorbed. Hence molecular volume and molar extinction coefficient are both first order parameters in achieving high conversion efficiencies and must be taken into account when designing new dyes for DSSCs. 相似文献
The aim of this study was to examine the changes in the trend and seasonal patterns in fatal crashes in New Zealand in relation to changes in economic conditions between 1970 and 1994. The Harvey and Durbin (Journal of the Royal Statistical Society 149 (3) (1986) 187-227) structural time series model (STSM), an 'unobserved components' class of model, was used to estimate models for quarterly fatal traffic crashes. The dependent variable was modelled as the number of crashes and three variants of the crash rate (crashes per 10,000 km travelled, crashes per 1,000 vehicles, and crashes per 1000 population). Independent variables included in the models were unemployment rate (UER), real gross domestic product per capita, the proportion of motorcycles, the proportion of young males in the population, alcohol consumption per capita, the open road speed limit, and dummy variables for the 1973 and 1979 oil crises and seat belt wearing laws. UERs, real GDP per capita, and alcohol consumption were all significant and important factors in explaining the short-run dynamics of the models. In the long-run, real GDP per capita was directly related to the number of crashes but after controlling for distance travelled was not significant. This suggests increases in income are associated with a short-run reduction in risk but increases in exposure to a crash (i.e. distance travelled) in the long-run. A 1% increase in the open road speed limit was associated with a long-run 0.5% increase in fatal crashes. Substantial reductions in fatal crashes were associated with the 1979 oil crisis and seat belt wearing laws. The 1984 universal seat belt wearing law was associated with a sustained 15.6% reduction in fatal crashes. These road policy factors appeared to have a greater influence on crashes than the role of demographic and economic factors. 相似文献