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Paramagnetic macrocyclic chelates show promise as magnetic resonance (MR) imaging contrast agents due to stability and relaxivity comparable to those of DTPA-type chelates. For the three copper and manganese macrocyclic complexes studied in aqueous solution, T1 and T2 relaxivities ranged from 0.14 to 5.88 mM-1sec-1 at 6.25 MHz. In rats, the intravenous administration of 16 mumol/kg of Mn(cyclam) caused the liver T1 relaxation rate to double at 15 minutes after injection. T1 measurements by pulsed MR imaging and manganese analyses on excised tissue showed that both relaxation rate (1/T1) and manganese content of liver and kidney increase linearly with the dosage of Mn(cyclam). The linear relationship between 1/T1 and manganese content can be considered an "in tissue" relaxivity plot for the agent. The resulting relaxivity is 54 mM-1sec-1 in liver, compared with 3.1 mM-1sec-1 in aqueous solution. Although this work is preliminary, the implication for medical MR imaging applications is that macrocyclic contrast agents can be effective at approximately one-tenth the current typical dose used for gadolinium DTPA. 相似文献
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Meijboom A Jansen A Kampman M Schouten E 《The International journal of eating disorders》1999,25(3):327-334
OBJECTIVE: Although self-esteem and overconcern with body shape and weight are considered to be closely connected in bulimia nervosa, little empirical research has been done to investigate the alleged link. METHOD: In this study, we examined experimentally whether overconcern with body shape and weight was connected with self-esteem in an analogue sample of high restrained eaters by means of a subliminal lexical decision task. RESULTS: It could indeed be demonstrated that low self-esteem and overconcern with body shape and weight are associated in high restrained eaters: after priming low self-esteem, the accessibility of subliminally presented body shape and weight stimuli was increased. The effect was not found with a supraliminal lexical decision task. DISCUSSION: Apparently, the automatic, nonconscious processing of body shape and weight words was influenced in high restrained eaters with a low state self-esteem, whereas the strategic, conscious processing was not. As soon as the body shape and weight stimuli were processed consciously, the initial increased accessibility was countered and the effect disappeared. 相似文献
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R. P. Beekman F. J. A. Beek M. G. Hazekamp E. J. Meijboom 《European journal of pediatrics》1997,156(7):516-520
In a 2 year period seven patients who presented with stridor, without respiratory compromise, and three patients without
obstructive symptoms were prospectively selected, and underwent MRI. In eight patients with a vascular ring and a pulmonary
sling, MRI delineated the vascular abnormality and normal great vessels were found in two patients.
Conclusion MRI successfully delineates the great vessels and demonstrates the presence of a vascular ring and pulmonary sling.
Received: 15 May 1996 / Accepted: 17 January 1997 相似文献