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41.
Proton magnetization transfer contrast (MTC) imaging, using continuous wave off-resonance irradiation, was performed on the rat brain in vivo at 4.7 Tesla. The observed MTC was studied in three different brain regions: the corpus callosum, the basal ganglia, and the temporal lobe. By systematically varying the offset frequency and the amplitude of the RF irradiation, the observed signal intensities for each region of interest were modeled using a system including free water and a pool of protons with restricted motions (R. M. Henkelman, X. Huang, Q. Xiang, G. J. Stanisz, SD Swanson, M. J. Bronskill, Magn. Res. Med. 29, 759 (1993)). Most of the relaxation parameters of both proton pools remained fairly constant for the three regions of interest, with a T2 value of about 9 micros for the immobilized protons, whereas the rate of exchange increased significantly from the temporal lobe to the corpus callosum. The optimal acquisition parameters for the improved MTC under steady-state saturation were found to be 2-10 kHz offset frequency and 500-800 Hz RF irradiation amplitude. Conversely, an irradiation amplitude of 3 kHz at an offset frequency of 12 kHz is required to minimize the direct effect of off-resonance irradiation. Such an approach could be extended to human brain imaging with the aim of characterizing tissue-specific disease.  相似文献   
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Mutation of the granulocyte-macrophage colony-stimulating factor (GM-CSF) gene by homologous recombination causes progressive pulmonary alveolar proteinosis (PAP) in GM-CSF-deficient mice (GM-/-). The present study tested whether adenovirus-mediated expression of GM-CSF alters the progression of PAP in GM-/- mice. Adult mice were pretreated with an anti-T cell receptor (TCR) antibody to block T cell-mediated immune response, followed by intratracheal instillation of deltaE1-E3 replication-deficient adenovirus expressing mouse GM-CSF (Av1mGM). Mice were killed 1, 3, and 5 weeks after treatment to assess lungs for GM-CSF, surfactant protein B (SP-B), alveolar macrophage maturation, and type II cell proliferation. GM-CSF was detected in BAL fluid from GM-/- mice 1 week after Av1mGM treatment, and GM-CSF mRNA was detected by RT-PCR through 5 weeks. Five weeks after Av1mGM treatment, PAP was improved and SP-B decreased as assessed by ELISA and immunostaining. Increased numbers of alveolar macrophages stained with alpha-naphthyl acetate esterase (alpha-NAE) following treatment with Av1mGM. Local expression of GM-CSF with a recombinant adenovirus ameliorated PAP in the GM-/- mice in association with enhanced maturation of alveolar macrophages.  相似文献   
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The photochromogenic mycobacteria do not all belong to one homogeneous species. With a simple heat-stable esterase (HSE) test it is possible to divide photochromogenic mycobacteria into two groups: HSE-positive--strongly pathogenic strains; and HSE-negative--weakly pathogenic strains. HSE-positive strains are mostly associated with pulmonary disease. HSE-negative strains are seldom associated with pulmonary disease, but are often associated with renal disease. It is rather difficult to draw a clear dividing line between pathogenic and non-pathogenic photochromogenic mycobacteria; and such a distinction probably does not exist in nature.  相似文献   
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A prospective study of the effects of the i.v. injection of 75 mg meperidine, alone or combined with 25 mg promethazine, was conducted by continuous and direct monitoring of the fetus and of intrauterine pressure. The study was carried out in 16 primiparas and 24 multiparas in active spontaneous labor with cervical dilatation of 3 to 4 cm. Administration of meperidine and of meperidine with promethazine was associated with an increase in uterine activity of 31 to 45% (Montevideo units), respectively. The most marked effects were on the amplitude of the uterine contractions. There was no significant change in uterine tone. A tetanic response was recorded in two patients who vomited after the administration of meperidine with promethazine and was followed by slowing of the fetal heart rate. In no other cases were there significant changes in fetal heart rate. Except for the latter two patients, no adverse effect of meperidine or of meperidine with promethazine on the fetal heart rate was noted. The condition of the newborns at birth was excellent in all but three cases, in two of which maternal amniotic infection and high fever were present.  相似文献   
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Market forces present the nursing profession with an urgency to prepare gerontological nurses to assume significant roles in the managed care industry. An understanding of the current managed care environment underscores the need for training. Nurses require a "managed care" skill-set encompassing a firm grasp of the organization, financing, delivery, and policy implications of managed care as well as advanced practice clinical skills and a sound business orientation. The importance of the consumer as a significant player in managed care is highlighted.  相似文献   
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鄂尔多斯盆地东南部中生界油气成藏条件分析   总被引:13,自引:0,他引:13  
在对鄂尔多斯分轩东南部构造、沉积演化及地层特征认识的基础上,分析了该地区油气成藏的主要地质条件,认为三叠系延长组三角洲砂体是该地区油气聚集的主要场所,局部也可能发育延安组河道砂岩油气藏,由差异压实作用形成的低幅度鼻褶构造是油气富集成藏的关键因素,延长组上覆地层遭受剥蚀的程度决定了油气藏保存条件的好坏。  相似文献   
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