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991.
The production of granulocyte-macrophage colony-stimulating factor (GM-CSF) by lymphocytes was examined in murine malaria. When spleen cells or lymph node cells from P. berghei-infected mice were cultured in vitro with malaria antigen, the GM-CSF production correlated with the incubation time up to 72 hours. When lymphocytes obtained at various days after infection were cultured with the antigen, GM-CSF became detectable as early as 2 days after infection, reached a peak at day 9 and then rapidly decreased. Production of GM-CSF was antigen-specific, and related to the dose of antigen. Treatment of lymphocytes with anti-Thy-1.2 antibody and complement resulted in almost complete loss of GM-CSF-producing activity, while treatment with either anti-CD4 or anti-CD8 antibody and complement resulted in partial loss of GM-CSF-producing activity, indicating that both CD4+ and CD8+ T cells are involved in GM-CSF production in malaria. GM-CSF exhibits glycoprotein nature, and has an apparent molecular weight of 36,000. The molecular properties of this T-cell derived GM-CSF were compared with those of known lymphokine GM-CSF. 相似文献
992.
993.
Routes to thermosetting polyethersulphones (PES) by endcapping an hydroxy terminated oligomer with thermally reactive propargyl, vinylbenzyl and cyanate groups were investigated. Model compounds were prepared to establish suitable routes to the reactive oligomers. DSC was used to study curing behaviour of oligomers and model compounds. 相似文献
994.
S Sussman VC Parker C Lopes DL Crippens P Elder D Scholl 《Canadian Metallurgical Quarterly》1995,30(9):1141-1164
Two studies are described which provide evaluations for two brief videotapes developed as supplemental materials in the prevention of tobacco use among African-American adolescents. One videotape (the "soap opera") provides a more general audience-oriented presentation of prevention material and it was filmed primarily at a shopping mall, whereas the other videotape (the "rap") provides a "hip-hop generation" presentation, and it was filmed primarily at an outdoor hangout. The first study compared the two videotapes against each other. The second study compared the two videotapes combined in the same presentation, controlling for order of presentation, against a discussion group control. The results of the two studies indicated few differences in receptivity to the two videotapes among primarily African-American and Latino young adolescents. The rap videotape was rated as more accurate in its depiction of the African-American lifestyle, although both videotapes were equally liked. When shown together, the videotapes were not found to be superior in decreasing behavioral intention to smoke compared to a discussion group control. No change in trial of smoking was observed within or across conditions measured over a pre-post summer interval. These data suggest that "culturally sensitive" videotapes have no more of a short-term effect on youth than do other types of brief interventions which involve minority implementers. 相似文献
995.
With advancing age, a series of structural, architectural and compositional modifications take place in the vasculature. The diameter of the vessels tends to increase, and thickening of intimal and medial layers is often observed. In the subendothelial space, blood-derived leukocytes and an increased amount of "activated" smooth muscle cells are present. Extracellular matrix accumulates and becomes particularly rich in glycosaminoglycans. Collagen content increases, while elastin fibers appear progressively disorganized, thinner, and frequently fragmented. These changes in the normal architecture of the vessel wall, that could be referred to as "the vasculopathy of aging", are likely to be the consequence of adaptive mechanisms to maintain normal conditions of flow, mechanical stress and/or wall tension. Although many of these features are similar to the histological findings of the atherosclerotic vessels, atherosclerosis and age-related "vasculopathy" are two distinct phenomena. Nonetheless, several experimental observations in animal models suggest a special link between "the vasculopathy of aging" and atherosclerotic disease, and suggest a particular predisposition of the old vessel to develop the atherosclerotic lesion. Compared to vessels from young animals, older ones show a greater reactivity to mechanical injury and to chronic insults. This may reflect changes in the biology of the vessels that are "intrinsic" to the aging process. Indeed, aging affects the function and responsiveness of the endothelium and vascular smooth muscle cells. Endothelial permeability is increased with age, while ability to produce vasoactive substances declines. Smooth muscle cells from old individuals show a growth advantage over the young ones, and display an increased ability to migrate toward chemoattractants. Moreover, the accumulation of advanced glycation end products (AGEs) occurring with aging can trigger a series of cellular events, such as cellular oxidative stress, expression of leukocyte adhesion molecules, endothelial transmigration of monocytes, and smooth muscle cell chemotaxis, all considered important prelesional events in the atherogenesis process. Taken together, the changes occurring with aging, while unproven to initiate lesion formation per se, are likely to accelerate the development of the atherosclerotic plaque and contribute to increased severity of this disease in the elderly. 相似文献
996.
997.
Eight typically developing children first learned to select pictures in response to dictated words in a three-choice matching-to-sample format. Next, the matching-to sample baseline was transformed via a stimulus control shaping procedure: Matching trials displayed two pictures and a third stimulus (termed a "blank" comparison). The blank was to be selected if the dictated sample did not match either of the displayed pictures. The blank comparison baseline was then used to evaluate the children's response to matching displays that presented novel sample and comparison stimuli. The blank comparison method permitted the children to indicate whether the novel sample-comparison pair were related (by selecting the picture) or not related (by selecting the blank). The method was used to evaluate emergent symbolic mapping and learning of new word:picture matching relations by the children. This study illustrates new, potentially more informative methods for analyzing symbol mapping in young children. The methods were shown to have considerable promise for advancing theoretical analyses of emergent mapping in both behavior analytic and developmental language research. 相似文献
998.
If controlling or reducing healthcare costs while providing the best possible patient service is your goal, then word processing is an auxiliary method of information processing that you should examine closely. Handled properly, word processing delivers significant benefits: improved collections, increased cash flow, reduced paperwork, increased donations to healthcare foundations, improved productivity and improved document quality. Mishandled, word processing does little more than provide you with expensive typewriters. 相似文献
999.
1000.