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31.
Y Wu EC Unger TP McCreery RH Sweitzer D Shen G Wu MD Vielhauer 《Canadian Metallurgical Quarterly》1998,33(12):880-885
RATIONALE AND OBJECTIVES: A thrombus-specific ultrasound contrast agent, MRX-408, has been developed recently. This agent consists of phospholipid-coated microbubbles with a ligand capable of targeting the GPIIb/IIIa receptor, thereby allowing the microbubbles to bind with thrombi rich in activated platelets. In vitro and in vivo animal experiments have been conducted to examine imaging enhancement and sonothrombolysis using this agent compared with a nontargeted agent. METHODS: For clot binding, blood-smeared slides were incubated with microbubbles and examined under a light microscope. Change in backscatter signals from the blood clots after binding was examined by both an ultrasound scanner and two single-element transducers arranged in a transmitter-receiver pair. For clot lysis, either 1-MHz or 20-KHz ultrasound was used to enhance the lysing effects of MRX-408 with or without urokinase. RESULTS: Evidence of binding was demonstrated under a microscope. In vitro experiments showed that the "acoustic signature", or properties, of blood clots changed after binding. Clots became more echogenic and nonlinear. In vivo fundamental ultrasound imaging confirmed that as a result of binding, blood clots were more visible, the area of detection was improved, and shadowing behind clots was more noticeable. Under 1-MHz ultrasound and 30 minutes of treatment, lysis efficiency reached 34% with MRX-408, whereas there was no visible clot lysis with saline. CONCLUSION: The results of these preliminary studies show that as a contrast agent, MRX-408 enhanced clots under ultrasound imaging and facilitated sonothrombolysis with or without thrombolytic drugs. 相似文献
32.
Smooth muscle cell to elastic lamina connections in developing mouse aorta. Role in aortic medial organization 总被引:1,自引:0,他引:1
EC Davis 《Canadian Metallurgical Quarterly》1993,68(1):89-99
BACKGROUND: The structural and functional intigration of smooth muscle cells and elastic laminae in the aortic media is not well established. Detailed information concerning normal ultrastructural features of the aortic media will provide a better understanding of the medial changes that occur in vascular diseases such as hypertension and aortic aneurysms. EXPERIMENTAL DESIGN: The ultrastructural development and organization of connections between smooth muscle cells and elastic laminae in the mouse aortic media were studied by light and electron microscopy. RESULTS: Early in development, the smooth muscle cells become linked to the elastic laminae by bundles of microfibrils. These microfibrils become progressively infiltrated with elastin so as to form extensions of elastin from the elastic laminae in the adult media. Each elastin extension spans obliquely from the elastic lamina to the surface of the smooth muscle cell where it attaches in a region of membrane occupied by an intracellular membrane-associated dense plaque. On the cytoplasmic face of the plaque, a contractile filament bundle penetrates and anchors in an orientation similar to that of the extracellular elastin extension. The contractile filament bundle traverses the cell obliquely and anchors in a dense plaque on the opposite side of the cell that is in turn linked to the next elastic lamina by another elastin extension. The extracellular elastin extensions and the intracellular contractile filament bundles thus form a "contractile-elastic unit," a continuous line of structures that links adjacent elastic laminae. The oblique orientation of the contractile-elastic units reverses direction in successive smooth muscle cell layers in a herringbone-like pattern. Thus, tension transmitted to one elastic lamina by the smooth muscle cells on either side results in a uniform force exerted on the elastic lamina in one circumferential direction, that on the adjacent elastic laminae being in the opposite direction. CONCLUSIONS: Results from this study demonstrate the presence of smooth muscle cell to elastic lamina connections that form early in development as contractile-elastic units; basic units of aortic medial ultrastructure. The overall organization of the contractile-elastic units within the aortic media is proposed to provide a means for coordinating contractile and elastic tensions in response to mechanical stresses imposed on the vessel wall. 相似文献
33.
EC Miller 《Canadian Metallurgical Quarterly》1993,80(10):684-688
Three states have established psychiatric security review boards mandated to primarily provide protection from the potentially destructive behavior of insanity acquitees. Each year in Florida there are 100 of these patients; 5% have been involved in capital offenses. These boards, as compared with the extant judiciary system, are more effective and parsimonious and serve the end of primary prevention. It is recommended that the plea, "not guilty by reason of insanity," be changed to "guilty but insane." The change is largely semantic but should result in greater prosecutorial and public acceptance of the insanity plea and be more in keeping with individual freedom for patients as provided under the Constitution. 相似文献
34.
B. Yang H. P. Degischer H. Presslinger G. Xia P. Reisinger 《BHM Berg- und Hüttenm?nnische Monatshefte》2005,150(9):313-320
High temperature tensile test results of speciments from continuously cast steel slabs are investigated during cooling from 1250°C. Experiments in the temperature range from 1025°C down to room temperature are presented for nine heats of steels with carbon contents varying between 0.038 and 0.96 mass%. The influence of secondary precipitates on strength, strain hardening and reduction of area at fracture are discussed in relation to a temperature normalized by Ar3. The embrittlement of the hypereutectic steel by tertiary carbides indicates severe crack sensitivity below A. The minimum toughness just above Ar3 is attributed to increased N and Nb content. 相似文献
35.
Ph. Hehenberger P.-J. Wagner H. Reisinger T. Grasser 《Microelectronics Reliability》2009,49(9-11):1013-1017
Initial NBTI degradation is often explained by elastic hole trapping which also considerably distorts long-term measurements. In order to clarify this issue, short-term NBT stress measurements are performed using different temperatures, stress voltages, and oxide thicknesses. The data shows a clear temperature activation and a super-linear voltage dependence, thereby effectively ruling out elastic hole tunneling. Rather, our data supports an explanation based on a thermally activated hole capture mechanism. 相似文献
36.
37.
Retrospective analyses of data from the authors' program of research on hypnosis and memory are presented, with special emphasis on effects observed among low hypnotizable individuals. In Experiment 1, participants completed seven forced-recall trials in an attempt to remember a series of pictures that had been shown 1 week earlier. For half the participants, the middle five trials were carried out using hypnotic procedures; the remaining participants performed all recall attempts in a motivated waking condition. Hypnosis failed to enhance correct recall for either high or low hypnotizable participants beyond the hypermnesia and reminiscence effects associated with repeated retrieval attempts over time. However, whereas high hypnotizable participants produced substantial numbers of confident recall errors (i.e., intrusions) independent of the use of hypnosis, low hypnotizable participants exposed to hypnotic procedures reported significantly more intrusions than their counterparts in the waking condition. In Experiment 2, participants were asked to identify whether specific recollections, reported during two forced-interrogatory recall tests conducted 1 week earlier, had originated in the first or second of those tests. A general bias to misattribute previously reported recollections to the first of two recall occasions was observed; however, the effect was greatest among low hypnotizables who had undergone the second recall attempt in hypnosis. The findings imply that highly hypnotizable individuals are not unique in their vulnerability to distortions of memory induced by hypnotic techniques. Individuals of lesser hypnotic capacity also manifest memory alterations when exposed to such procedures. 相似文献
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39.
The homeobox gene Otx2 is a mouse cognate of the Drosophila orthodenticle gene, which is required for development of the brain, rostral to rhombomere three. We have investigated the mechanisms involved in this neural function and specifically the requirement for Otx2 in the visceral endoderm and the neuroectoderm using chimeric analysis in mice and explant recombination assay. Analyses of chimeric embryos composed of more than 90% of Otx2-/- ES cells identified an essential function for Otx2 in the visceral endoderm for induction of the forebrain and midbrain. The chimeric studies also demonstrated that an anterior neural plate can form without expressing Otx2. However, in the absence of Otx2, expression of important regulatory genes, such as Hesx1/Rpx, Six3, Pax2, Wnt1 and En, fail to be initiated or maintained in the neural plate. Using explant-recombination assay, we could further demonstrate that Otx2 is required in the neuroectodem for expression of En. Altogether, these results demonstrate that Otx2 is first required in the visceral endoderm for the induction, and subsequently in the neuroectoderm for the specification of forebrain and midbrain territories. 相似文献
40.
Aiming at finding out the ergonomics conditions of the nursing personnel in a hospital admission unit, the authors utilized as a methodological presupposition the search for a global experienced work situation through the analysis of some elements as: the man (nursing worker); the work activity (prescribed duty, real activities and work position) and the environment (temperature, noise and illumination). The authors selected the Cardiology admission unit for the site of their research. The results verified that the nursing workers the mentioned unit face problems related to salaries, work installations, relationship, work organization, levels of formation and the activities executed. The authors suggested some recommendations. 相似文献