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排序方式: 共有660条查询结果,搜索用时 15 毫秒
1.
Factors influencing women to undergo screening mammography 总被引:2,自引:0,他引:2
2.
Braffman BH; Coleman BG; Ramchandani P; Arger PH; Nodine CF; Dinsmore BJ; Louie A; Betsch SE 《Radiology》1994,190(3):797
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Rupture of the distal biceps tendon: evaluation with MR imaging 总被引:2,自引:0,他引:2
5.
Androgen receptor YAC transgenic mice carrying CAG 45 alleles show trinucleotide repeat instability 总被引:1,自引:15,他引:1
La Spada AR; Peterson KR; Meadows SA; McClain ME; Jeng G; Chmelar RS; Haugen HA; Chen K; Singer MJ; Moore D; Trask BJ; Fischbeck KH; Clegg CH; McKnight GS 《Human molecular genetics》1998,7(6):959-967
X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG
repeat expansion in the first exon of the androgen receptor (AR) gene.
Disease-associated alleles (37-66 CAGs) change in length when transmitted
from parents to offspring, with a significantly greater tendency to shift
size when inherited paternally. As transgenic mice carrying human AR cDNAs
with 45 and 66 CAG repeats do not display repeat instability, we attempted
to model trinucleotide repeat instability by generating transgenic mice
with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions
in their genomic context. Studies of independent lines of AR YAC transgenic
mice with CAG 45 alleles reveal intergenerational instability at an overall
rate of approximately 10%. We also find that the 45 CAG repeat tracts are
significantly more unstable with maternal transmission and as the
transmitting mother ages. Of all the CAG/CTG repeat transgenic mice
produced to date the AR YAC CAG 45 mice are unstable with the smallest
trinucleotide repeat mutations, suggesting that the length threshold for
repeat instability in the mouse may be lowered by including the appropriate
flanking human DNA sequences. By sequence-tagged site content analysis and
long range mapping we determined that one unstable transgenic line has
integrated an approximately 70 kb segment of the AR locus due to
fragmentation of the AR YAC. Identification of the cis - acting elements
that permit CAG tract instability and the trans -acting factors that
modulate repeat instability in the AR YAC CAG 45 mice may provide insights
into the molecular basis of trinucleotide repeat instability in humans.
相似文献
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Release of cytokines during generation of lymphokine-activated killer (LAK) cells by IL-2. 总被引:4,自引:0,他引:4
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G A Limb A Meager J Woolley M Wadhwa J Biggerstaff K A Brown R A Wolstencroft 《Immunology》1989,68(4):514-519
Supernatants of IL-2-activated mononuclear cells (MNC) that displayed an optimal lymphokine-activated killer (LAK) cell activity at 48-72 hr in culture were found to contain increased levels of tumour necrosis factor alpha (TNF alpha), interleukin-1 alpha (IL-1 alpha) and interferon-gamma (IFN-gamma) when compared with supernatants from mononuclear cells cultured in the absence of IL-2. The concentration of TNF alpha and IL-1 alpha produced by MNC at 24 hr was either increased or maintained by extending the cultures to 96 hr. In contrast, TNF beta was only detected at very low levels after 72-96 hr culture, irrespective of whether IL-2 was present or absent. Optimal concentrations of IL-2 needed to induce maximum release of TNF alpha, IL-1 alpha and IFN-gamma by MNC varied among different individuals. Enriched populations of lymphocytes secreted higher levels of all measured cytokines upon activation with IL-2 in contrast to untreated cells. Supernatants from purified monocyte preparations contained high concentrations of TNF alpha and IL-1 alpha regardless of the presence of IL-2 in the cell cultures. This work suggests that in addition to the generation of LAK cell activity, by promoting the release of other cytokines with potential anti-tumoricidal activity, IL-2 may be amplifying cell-mediated cytotoxicity, which is associated with protection against neoplastic disease. 相似文献
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It is well recognized that the ability to cryopreserve unfertilizedhuman oocytes would make a significant contribution to infertilitytreatment. However, despite considerable interest, very fewsuccessful pregnancies have arisen from cryopreserved oocytesafter thawing, insemination and transfer of the subsequent embryo.The reasons for this lack of progress may well result from adearth of information on how the various biophysical changesduring a cryopreservation regimen affect human oocyte function.Recently, fundamental studies on the effects of cooling, membranepermeability, cryoprotectant addition and ice formation havebeen performed on human oocytes by a number of groups, and theseform the basis of the current review. It is likely that successfulhuman oocyte cryopreservation will only follow once these factorsare fully understood, but the existing base of knowledge shouldprovide a platform for further improvements in the techniquescurrently employed. 相似文献
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