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Although a large percentage of the volume of human restenotic arterial lesions is occupied by extracellular matrix (ECM), the composition and organization of this ECM are not well characterized. In this study, restenotic segments taken from 30 human peripheral arteries by directional atherectomy at times ranging from 13 days to 36 months after angioplasty were analyzed for specific patterns of ECM composition and organization by light and electron microscopic histochemistry and immunohistochemistry. Histochemical analysis revealed the presence of distinct zones, enriched either in proteoglycans or fibrillar collagen. Most sections contained these regions juxtaposed to each other. The frequency of these two distinct ECMs did not change as a function of time after angioplasty. The collagen-rich zone usually contained elongated smooth muscle cells spaced close together except in regions resembling fibrous plaques. The proteoglycan-rich ECM contained both elongated and stellate-shaped smooth muscle cells randomly arranged and separated by wide distances. This region resembled the loose-connective-tissue-containing myxoid region typical of restenotic lesions. Immunohistochemical analysis of these regions revealed that the proteoglycan-containing zone stained intensely for versican, a large interstitial chondroitin sulfate proteoglycan, whereas the collagen-containing areas were mostly negative for versican but positive for type I collagen. The versican-positive regions also immunostained for biglycan, a small leucine-rich dermatan sulfate proteoglycan, and sparsely for elastin. However, both of these ECM molecules were present in the versican-negative type I collagen-positive regions of the lesions. These results suggest that the development of restenotic lesions involves localized deposits of specific ECM molecules that may play a role in the asymmetric renarrowing of this tissue after angioplasty. 相似文献
43.
Coulson Seana; Federmeier Kara D.; Van Petten Cyma; Kutas Marta 《Canadian Metallurgical Quarterly》2005,31(1):129
Researchers using lateralized stimuli have suggested that the left hemisphere is sensitive to sentence-level context, whereas the right hemisphere (RH) primarily processes word-level meaning. The authors investigated this message-blind RH model by measuring associative priming with event-related brain potentials (ERPs). For word pairs in isolation, associated words elicited more positive ERPs than unassociated words with similar magnitudes and onset latencies in both visual fields. Embedded in sentences, these same pairs showed large sentential context effects in both fields. Small effects of association were observed, confined to incongruous sentences after right visual hemifield presentation but present for both congruous and incongruous sentences after left visual hemifield presentation. Results do not support the message-blind RH model but do suggest hemispheric asymmetries in the use of word and sentence context during real-time processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Inside Cover: Substantial Receptor‐induced Structural Rearrangement of Rotavirus VP8*: Potential Implications for Cross‐Species Infection (ChemBioChem 15/2015) 下载免费PDF全文
46.
Transporting QoS adaptive flows 总被引:4,自引:0,他引:4
Distributed audio and video applications need to adapt to fluctuations in delivered quality of service (QoS). By trading
off temporal and spatial quality to available bandwidth, or manipulating the playout time of continuous media in response
to variation in delay, audio and video flows can be made to adapt to fluctuating QoS with minimal perceptual distortion. In
this paper, we extend our previous work on a QoS Architecture (QoS-A) by populating the QoS management planes of our architecture
with a framework for the control and management of multilayer coded flows operating in heterogeneous multimedia networking
environments. Two key techniques are proposed: i) an end-to-end rate-shaping scheme which adapts the rate of MPEG-coded flows
to the available network resources while minimizing the distortion observed at the receiver; and ii) an adaptive network service,
which offers “hard” guarantees to the base layer of multilayer coded flows and “fairness” guarantees to the enhancement layers
based on a bandwidth allocation technique called Weighted Fair Sharing. 相似文献
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BACKGROUND AND PURPOSE: A rapid but transient expression of c-fos after cerebral ischemia has been extensively documented. However, the mechanism of this induction and whether induction of c-fos is neuroprotective or detrimental to the brain after ischemia is presently not clear. Fasting before transient cerebral ischemia has been shown to reduce delayed neuronal necrosis and infarct volume. The purpose of the present study was to examine the effect of preischemic fasting for 24 hours on the expression of c-fos after transient focal cerebral ischemia. METHODS: Focal cerebral ischemia was induced by temporary occlusion of the right middle cerebral artery and both common carotid arteries for 60 minutes. Male Long-Evans rats weighting 250 to 300 g were randomly divided into two groups: fed (control group) and food deprived for 24 hours (fasted group) before ischemic surgery. Infarct volumes were measured on the basis of triphenyltetrazolium chloride-delineated infarct areas, and plasma glucose levels were determined by the glucose oxidase method. Temporal and spatial expression of c-fos was assessed by Northern blot analysis, in situ hybridization, and immunohistochemistry. RESULTS: Fasting for 24 hours before 60 minutes of ischemia resulted in a 26.6% decrease in preischemic plasma glucose levels and a 74.5% reduction in infarct volumes in the fasted group compared with the control group. A rapid but transient induction of c-fos mRNA was observed in the ischemic cortex in control animals after 60 minutes of ischemia. Fasting not only prolonged but also enhanced the intensity of c-fos expression in the ischemic cortex. Regional c-fos expression was also different between these two groups. CONCLUSIONS: The results support the contention that c-fos expression may be compatible with its purported neuroprotective role in selected experimental paradigms. The signaling mechanisms underlying the effect of fasting and subsequent lowering of plasma glucose levels on postischemic c-fos expression remain to be explored. 相似文献
49.
This letter proposes a method for estimating the instantaneous excess delay in time-varying mobile radio channel impulse response measurement data using image processing techniques. The method is shown by example to produce more accurate mean power delay profiles than those produced assuming either constant or linearly varying excess delay 相似文献
50.