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101.
D S Faffe G H Silva P M Kurtz E M Negri V L Capelozzi P R Rocco W A Zin 《Journal of applied physiology》2001,90(4):1400-1406
The dynamic mechanical properties of lung tissue and its contents of collagen and elastic fibers were studied in strips prepared from mice instilled intratracheally with saline (C) or silica [15 (S15) and 30 days (S30) after instillation]. Resistance, elastance, and hysteresivity were studied during oscillations at different frequencies on S15 and S30. Elastance increased from C to silica groups but was similar between S15 and S30. Resistance was augmented from C to S15 and S30 and was greater in S30 than in S15 at higher frequencies. Hysteresivity was higher in S30 than in C and S15. Silica groups presented a greater amount of collagen than did C. Elastic fiber content increased progressively along time. This increment was related to the higher amount of oxytalan fibers at 15 and 30 days, whereas elaunin and fully developed elastic fibers were augmented only at 30 days. Silicosis led not only to pulmonary fibrosis but also to fibroelastosis, thus assigning a major role to the elastic system in the silicotic lung. 相似文献
102.
S. I. Tkachenko A. R. Mingaleev V. M. Romanova A. E. Ter-Oganes’yan T. A. Shelkovenko S. A. Pikuz 《Plasma Physics Reports》2009,35(9):734-753
Distribution of matter in the discharge channel formed upon a nanosecond electrical explosion of a single wire in air and
vacuum was studied experimentally. Simultaneous use of optical, UV, and X-ray diagnostics made it possible to distinguish
qualitatively different regions of the discharge channel, such as the current-carrying layers and the region occupied by a
weakly conducting cold plasma. Several series of experiments with 25-μm-diameter 12-mm-long wires made of different materials
were performed. The charging voltage and the current amplitude were varied in the ranges of U
0 = 10–20 kV and I
max ∼ 5–10 kA, respectively. Explosion regimes with a current pause and with and without current interruption, as well as with
wire preheating in air and vacuum, were studied. Shadow and schlieren images of the discharge channel were obtained using
optical probing at the second harmonic of a YAG: Nd+3 laser (λ = 0.532 μm, τ ∼ 10 ns). In the experiments carried out in vacuum, X-ray images of the discharge channel were also
obtained using an X-pinch as a point source of probing radiation and UV images were recorded using a four-frame MCP camera. 相似文献
103.
Disseminated nocardiosis in three macaque monkeys 总被引:1,自引:0,他引:1
Extrapulmonary nocardiosis was diagnosed at necropsy in two rhesus monkeys (Macaca mulatta) and one pigtailed monkey (M. nemestrina) over a four-year period in a large primate center. Typical lesions were multiple pyogranulomatous foci in the liver, intestines, peritoneum, lung and brain. Partially acid-fast, branching, filamentous organisms were seen in all lesions. Nocardia sp. was isolated from two cases. We postulate that two of the monkeys were infected by the oral route because of the distribution of lesions. 相似文献
104.
1. As trees age, they undergo significant physiological and morphological changes. Nevertheless, tree ontogeny and its impacts on herbivores are often overlooked as determinants of plant–herbivore population dynamics and the strength of plant–herbivore interactions. 2. Juniperus (Cupressaceae) is a dominant, long‐lived conifer that serves as the sole host to a specialised assemblage of caterpillars. Over the past 150 years, several juniper species in western North America have expanded their geographic occupancy at local and regional scales, which has resulted in an increase in the number of immature trees on the landscape. Using assays in the laboratory, the effects of tree ontogeny on caterpillar performance and oviposition preference for two juniper specialist caterpillars, Callophrys gryneus (Lycaenidae) and Glena quinquelinearia (Geometridae), were examined. The study considered whether responses to tree ontogeny were consistent across caterpillar species and juniper host species. 3. Tree age was found to be a reliable predictor of caterpillar performance, with caterpillars developing more quickly and growing larger when fed foliage from young trees. Differences in the phytochemical diversity between foliage from trees of different ages might help to explain observed differences in caterpillar performance. Interestingly, the specialist butterfly, C. gryneus, displayed an oviposition preference for foliage from old‐growth Juniperus osteosperma trees, despite the fact that larvae of this species performed poorly on older trees. 4. It is concluded that young juniper trees are an important resource for the specialised Lepidopteran community and that tree ontogeny is an important component of intraspecific variation, which contributes to the structure of plant–herbivore communities. 相似文献
105.
106.
107.
108.
Activity of phosphoenolpyruvate carboxylase of an anthracycline-producing streptomycete 总被引:1,自引:0,他引:1
During fermantation studies on the production of anthracycline antibiotics by Streptomyces C5, it was observed that among the intermediate metabolism enzymes tested, only phosphoenolpyruvate carboxylase (PEPCase; EC 4.1.1.31) increased significantly in specific activity during stationary phase. The specific activity of the Streptomyces C5 PEPCase increased ca. 3-fold during antibiotic production phase from the logarithmic phase levels. To characterize the regulation of the enzyme further, the Streptomyces C5 PEPCase was purified 150-fold from crude extracts. Acetyl-CoA and Mg2+ were shown to be required for PEPCase activity. The activity of the partially purified PEPCase was stimulated slightly by fructose 1,6-bisphosphate and AMP, and was inhibited severely by oxaloacetate, aspartate, malate, succinate, ATP, citrate, and CoASH. 相似文献
109.
Anatomical and neurophysiological findings have demonstrated neuronal connections between the diencephalic habenular nuclei and brain stem serotonergic raphe nuclei. Therefore we examined some neurochemical consequences of habenular lesions. Sixteen hours and one week after bilateral lesions serotonin metabolism (as reflected by concentrations of its metabolite, 5-hydroxyindoleacetic acid) was significantly increased in the dorsal but not the median raphe nuclei. Unilateral lesions produced a proportionally smaller augmentation. Motron locomotor activity was enhanced during the light and dark illumination phases in lesioned animals but only attained statistical significance during the day. 相似文献
110.
E. N. Medvedeva N. A. Neverova T. E. Fedorova V. A. Babkin E. S. Meteleva A. V. Dushkin T. G. Tolstikova M. V. Khvostov M. P. Dolgikh 《Russian Journal of Bioorganic Chemistry》2010,36(7):853-859
It has been found by gel-penetrating chromatography and quantitative 13C NMR spectroscopy that mechanochemical processing of arabinogalactan isolated from the wood of the Siberian larch changes
the molecular mass distribution, monosaccharide composition, and the degree of branching of its macromolecules. This is due
to the partial destruction of polysaccharide macromolecules and subsequent recombination of resulting fragments. The intensity
of these processes depends on the conditions of mechanochemical processing. Based on the data of IR and 13C NMR spectra, the conclusion has been drawn that no functionalization of arabinogalactan macromolecules occurs under these
conditions. The toxicopharmacological properties of mechanically processed arabinogalactan have been studied. Its acute toxicity
is >5000 mg/kg. 相似文献