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91.
High-level expression and purification of a recombinant human erythropoietin produced using a baculovirus vector 总被引:1,自引:0,他引:1
Conditions presently have been established for the high-level expression and simplified purification of recombinant human erythropoietin produced in Spodoptera frugiperda cells. Expression, as mediated by infection with a recombinant baculovirus, was accomplished in suspension culture using reduced levels of serum and media supplements experimentally determined to provide optimum levels of factor production (500,000 U/L). Purification of this recombinant human erythropoietin to virtual homogeneity (greater than or equal to 99%) was accomplished via a simple three-step procedure involving isocratic elution from DEAE-Sephacel, reverse-phase high performance liquid chromatography (HPLC) on a C4 medium, and the single-step elution of purified hormone from concanavalin A agarose. Overall, an 890-fold purification was accomplished with a recovery of 80% as assayed in vitro. Biologically, this purified erythropoietin is highly active, possessing a specific activity in vitro of 200,000 U/mg protein. Chemically, this erythropoietin (molecular weight [mol wt] 26,200) appears exceptionally uniform in its oligosaccharide constitution (30%) as contrasted with heterogeneously glycosylated erythropoietins derived from mammalian cells (mol wt 30,000 to 38,000; 40% to 50% complex-type oligosaccharide). Thus, human erythropoietin as presently produced in an insect cell line comprises not only an abundant source of highly active, readily purified hormone for studies of its mechanism of action and cell surface receptor, but also represents a uniquely homogeneous form that should prove advantageous for direct structural analyses. 相似文献
92.
93.
During computed tomography (CT) pelvimetry of two pregnant women, bony abnormalities of the fetuses were noted on the scout images that were not confirmed at delivery. To explore the cause of these artifacts, specimen long bones were manipulated in various ways during CT scout imaging. Artifacts like those seen during in vivo imaging were found to be caused by motion of the object. The CT scout view is an example of an image produced by a digital system that uses a scanning beam. This type of digital system is being used for several types of body imaging including screening for scoliosis and chest radiography. Attention to motion artifacts should decrease diagnostic errors and aid further development of these systems. 相似文献
94.
Rokey R; Verani MS; Bolli R; Kuo LC; Ford JJ; Wendt RE; Schneiders NJ; Bryan RN; Roberts R 《Radiology》1986,158(3):771-774
The feasibility of using magnetic resonance (MR) imaging to estimate myocardial infarct size was explored in an in vitro model using only the inherent differences in contrast between infarcted and noninfarcted myocardium. Eight dogs underwent coronary occlusion; their hearts were removed 6 hours later. Estimates of T2 for normal and infarcted myocardium were derived from MR images. Infarct size was quantified anatomically using triphenyltetrazolium-chloride (TTC) staining and compared with MR estimates. The T2 values derived from the images clearly discriminated between infarcted (126 +/- 22 msec) and normal myocardium (88 +/- 10 msec, P less than .05), providing images with good contrast between normal and infarcted myocardium. Comparable differences in T2 values were also noted from spectrometric determinations. Estimates of infarct size by MR imaging compared well with TTC estimates (r = 0.98) over a wide range of infarct sizes from 3% to 29% of the left ventricular mass. These results suggest the potential for in vivo quantification of infarct size based on the inherent contrast difference between infarcted and normal myocardium. 相似文献
95.
A case of recurrent hemoptysis following bronchial artery embolization is presented. The bleeding was successfully controlled by embolization of the thyrocervical trunk. 相似文献
96.
Hepatic parenchymal gas was demonstrated by computed tomography in a boy who had sustained severe blunt trauma to the abdomen 12 hours earlier. There was no clinical evidence of infection. Although previous reports have suggested that hepatic parenchymal gas indicates the presence of infection, such gas may also be a manifestation of severe blunt trauma without infection. 相似文献
97.
98.
Human breast lesions: characterization with proton MR spectroscopy 总被引:31,自引:0,他引:31
99.
JESPER NØRREGAARD PHILIP TØNNESEN KÅRE SIMONSEN LARS PETERSEN URBAIN SÄWE 《Addiction (Abingdon, England)》1992,87(8):1189-1194
Reports of smoking cessation studies often claim that many relapsed subjects reduce their smoking. We investigated the smoking habits of relapsers 1 year after quitting in a smoking cessation trial using nicotine or placebo patches. All 289 participants in that study were summoned to a 1-year follow-up visit–148 (57%) of 259 relapsers attended, as did all 30 sustained abstainers. Fewer than 1% of the subjects had quit spontaneously after the primary relapse. Daily cigarette consumption, standard nicotine yield per cigarette, saliva cotinine concentration, expired carbon monoxide level and two nicotine dependency scales were assessed at entry and at the 1-year follow-up. In five of these six smoking-related characteristics, there was a small but significant mean reduction of 7%-27%. A significant weight gain of 0.5 ± 2.9 kg (mean ± SD) was recorded in the relapsers compared with 4.8 ± 4.2 kg for abstainers (p < 0.001). It is concluded that smoking habits in relapsers are relatively unchanged, and thus the most important outcome measure in smoking cessation trials is abstinent subjects. 相似文献
100.
P.N. Cooper D. Neary D. Denning G.M. Cleator RE. Klapper 《European journal of neurology》1996,3(3):267-271
Two cases of Coxsackie B viral meningo-encephalitis in pregnant women are described. Both patients recovered well and delivered healthy babies, but because of delay in establishing the aetiology of their infections both mothers, and one child, received acyclovir therapy. The differential diagnosis of non-pyogenic meningo-encephalitis in late pregnancy can present particular problems: clinicians caring for such women should remain aware of the potential for enteroviral infection in their patients, and take appropriate action to prevent cross-infection in neonatal units. 相似文献