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排序方式: 共有906条查询结果,搜索用时 31 毫秒
1.
A new range of stand magnifiers has been released by the COIL company in the United Kingdom. Examination of these magnifiers reveals that they fail to deliver the rated magnifications labelled prominently on the appliances, as a result of the manufacturer's conformance with the requirements of the German DIN standard and the use of back vertex power (F'v) rather than equivalent dioptric power (Fm) of the magnifier. In this study we provide information on the optometric parameters of these new stand magnifiers that will assist the more accurate specification of improvements in vision expected from their use. 相似文献
2.
Jose S. Pulido Ikuko Sugaya Jordan Comstock Kiminobu Sugaya 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》2007,245(6):889-893
Purpose Reelin is important in the guidance of neuronal stem cells in the central nervous system during normal development. We wished
to determine whether reelin is expressed in the retina and cornea after injury.
Methods Mice underwent laceration of their retina as well as corneal epithelial debridement. The mice were sacrificed at 3 days, and
eyes were fixed and stained for reelin expression and reelin messenger ribonucleic acid (mRNA).
Results In normal eyes, reelin was expressed only at very low levels in the ganglion cell layer of the retina and the endothelial
cell layer of the cornea. In injured eyes, there was marked expression in reelin immunoreactivity in the retina and cornea.
Reelin gene expression was seen in the retina and cornea.
Conclusions Reelin is expressed during normal retinogenesis. This study shows that reelin is also upregulated following injury to the
retina and cornea. The expression of reelin following injury suggests that reelin may play an important role in regulating
stem cell trafficking in neuronal and nonneuronal tissues following injury similar to its role in normal organogenesis.
For consideration of publication in Graefe’s Archive for Clinical and Experimental Ophthalmology. 相似文献
3.
D Rudy D A Sica T Comstock J Davis J Savory A C Schoolwerth 《The International journal of artificial organs》1991,14(10):625-629
The influence of a sodium citrate/citric acid mixture on the gastrointestinal (GI) absorption of aluminum (Al) from an Al(OH)3 preparation was evaluated in six stable maintenance hemodialysis patients. Plasma Al concentrations were determined serially after each of the following treatment sequences (I) Al(OH)3; (II) Al(OH)3 + sodium citrate/citric acid; (III) sodium citrate/citric acid; (IV) Al(OH)3 + NaHCO3. AUC0-8 for plasma Al from 0 to 8 hours was significantly greater (p less than 0.05) for Al(OH)3 + sodium citrate/citric acid (73 +/- 23 micrograms.hr/l; mean +/- SEM) than Al(OH)3 (16 +/- 30 micrograms.hr/l); sodium citrate/citric acid (-27 +/- 14 micrograms.hr/l); or Al(OH)3 + NaHCO3 (6 +/- 22 micrograms.hr/l). The 24 hour Al level remained above baseline (p less than 0.03) following Al(OH)3 + sodium citrate/citric acid (31 +/- 12 (pre) vs 54 +/- 14 micrograms/l (post), in contradistinction to study limb: l (34 +/- 14 vs 30 +/- 12 micrograms/l); III (79 +/- 40 vs 65 +/- 35 micrograms/l); and IV (71 +/- 37 vs 66 +/- 42 micrograms/l). We conclude that the GI absorption of Al from Al(OH)3 is enhanced by citrate in patients undergoing hemodialysis and that elevations of plasma Al persist longer. The concomitant administration of citrate and Al-containing phosphate (PO4) binders should be avoided in patients with end-stage renal disease (ESRD). NaHCO3 may serve as an alternative therapy for metabolic acidosis with less risk of enhancing Al absorption. 相似文献
4.
Dehydroepiandrosterone and dehydroepiandrosterone sulfate are steroids which may be associated with the development of breast cancer. To examine the association between serum levels of dehydroepiandrosterone and dehydroepiandrosterone sulfate and the risk of developing premenopausal breast cancer, we measured hormone levels in 15 women who donated blood to a community-based serum bank in 1974 and who subsequently developed premenopausal breast cancer and in 29 matched controls from the same group of volunteers. The mean serum level of dehydroepiandrosterone among cases was 10% lower than among controls. The risk of developing breast cancer for women in the highest tertile compared with the lowest tertile of serum dehydroepiandrosterone was 0.40 with a suggestion of a dose-response trend with increasing levels. No consistent association between dehydroepiandrosterone sulfate and the risk of premenopausal breast cancer was evident. In contrast to postmenopausal breast cancer, a protective effect of dehydroepiandrosterone against premenopausal breast cancer is suggested, but because of the small sample size, the results of this study need to be replicated by others. 相似文献
5.
Pheochromocytoma and paraganglioma: comparison of MR imaging with CT and I-131 MIBG scintigraphy 总被引:6,自引:0,他引:6
To ascertain the magnetic resonance (MR) imaging characteristics of pheochromocytomas and paragangliomas and to compare MR with computed tomography (CT) and iodine-131 metaiodobenzylguanidine (I-131 MIBG), 19 patients (18 with pheochromocytomas, one with a paraganglioma) were studied. The 18 patients with pheochromocytomas had had positive findings with I-131 MIBG scintigraphy. Abdominal pheochromocytomas were generally hypointense compared with normal liver on T1-weighted MR images and extremely hyperintense on T2-weighted MR images. MR imaging was preferable to CT in the evaluation of primary pheochromocytomas due to superior tissue characterization, particularly in the patient with hypertension and borderline catecholamine levels. For patients with recurrent or metastatic disease, the data suggest that I-131 MIBG scintigraphy is the examination of choice. 相似文献
6.
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9.
Chaperonin-mediated assembly of wild-type and mutant subunits of human propionyl-CoA carboxylase expressed in Escherichia coli 总被引:1,自引:0,他引:1
We developed a bacterial expression system for the human alpha and beta
cDNAs of propionyl-CoA carboxylase (PCC). These cDNAs (less the putative
mitochondrial matrix targeting presequences) were co-expressed in
Escherichia coli on one plasmid vector with each cDNA having its own
IPTG-inducible promoter. Only negligible amounts of active PCC were
measured despite the presence of both alpha and beta subunits as indicated
by Western blot analysis and the almost complete biotinylation of the alpha
subunit. Co-expression of this plasmid with a second plasmid vector
over-expressing the E. coli chaperonin proteins, groES and groEL, resulted
in a several hundred-fold increase in PCC specific activity, to a level
comparable with that found in crude human liver extracts. PCC was partially
purified on monomeric avidin affinity resin and the presence of both alpha
and beta subunits was demonstrated, thereby confirming the assembly of both
subunits into an active enzyme. Deficiency of either alpha PCC or beta PCC
results in propionic acidemia, an autosomal recessive disorder. We used
this expression system to characterize one missense mutation previously
described in five Japanese alleles, namely C1283T (Thr428lle) in beta PCC.
This mutation, when expressed in E.coli under the same conditions as that
of wild-type PCC, had null activity, despite the presence of assembled
alpha PCC and beta PCC subunits. This bacterial expression system can be
useful for analysis of either alpha PCC or beta PCC mutations. Our findings
indicated that the groES and groEL chaperonin proteins were essential for
folding and assembly of the human PCC heteromeric subunits.
相似文献
10.
The capsule and O antigen in Vibrio cholerae O139 Bengal are associated with a genetic region not present in Vibrio cholerae O1. 总被引:11,自引:2,他引:11
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L E Comstock D Maneval Jr P Panigrahi A Joseph M M Levine J B Kaper J G Morris Jr J A Johnson 《Infection and immunity》1995,63(1):317-323
Vibrio cholerae O139 Bengal, although closely related to V. cholerae O1 El Tor, produces a polysaccharide capsule and has a distinct O antigen. We have identified a chromosomal region of at least 11 kb, as defined by three TnphoA mutations, that is required for the expression of both polysaccharides. Electron microscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis show that these TnphoA mutants have lost the abilities both to express capsule and to produce lipopolysaccharide beyond the core oligosaccharide. Reactivity with O139 typing serum and resistance to serum are also lost in the mutants. DNA probes for this region do not hybridize with O1 V. cholerae but do react with other vibrios, implying that the region was recently acquired. 相似文献