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排序方式: 共有937条查询结果,搜索用时 312 毫秒
1.
F G Diaz R D Fessler B Velardo C Kennedy H Wilner 《Journal of clinical neuroscience》1994,1(4):222-230
Aneurysms arising from the internal carotid circulation represent 85% of all intracranial aneurysms. The intimate relationship of the internal carotid artery and its branches with the brain and cranial nerves, and the distribution of the internal carotid artery flow, make these aneurysms challenging, and potentially complicated in their surgical management. Great attention to detail, and clear understanding of the operative anatomy of the carotid system, facilitate the safe and successful treatment of these aneurysms. The surgical experience with 475 anterior circulation aneurysms treated from 1980 to 1992 is presented. The aneurysms arose from the internal carotid artery: 230(40%), middle cerebral artery: 152(32%), and anterior cerebral artery: 133(28%). Of aneurysms arising from the internal carotid artery, there were 142(30%) from the posterior communicating artery; internal carotid bifurcation: 29(6%), and anterior choroidal artery: 19(4%). There were 62(13%) giant aneurysms evenly distributed among the middle cerebral, internal carotid bifurcation and anterior cerebral artery. Serious neurological morbidity was observed in 13(3%) patients, who presented a combination of different neurological symptoms including: hemiplegia 3, hemiparesis 6, dysphasia 7, and loss of vision 4. Two patients developed a myocardial infarct and survived. Mortality occurred in 16(3%); these patients died from: a hemispheric infarction 7, severe vasospasm 6, myocardial infarction 2, and pulmonary emboli 1. All aneurysms appeared angiographically obliterated. Vasospasm was observed in 75(16%) patients of which nine were symptomatic, and six of them died. Six major arterial trunks were occluded in the post-operative angiogram, and three patients had occlusion of the internal carotid artery, not identified during surgery. Three of these patients with unexpected occlusions died from a major cerebral infarction, and three had lasting hemipareses and dysphasia. Surgical correction of internal carotid aneurysms can be conducted safely when the anatomical characteristics of the intracranial vessels is preserved, and when these patients are treated with appropriate medical support. 相似文献
2.
Factors influencing women to undergo screening mammography 总被引:2,自引:0,他引:2
3.
Braffman BH; Coleman BG; Ramchandani P; Arger PH; Nodine CF; Dinsmore BJ; Louie A; Betsch SE 《Radiology》1994,190(3):797
4.
5.
Rupture of the distal biceps tendon: evaluation with MR imaging 总被引:2,自引:0,他引:2
6.
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
7.
8.
This paper describes a statistical image reconstruction method for x-ray CT that is based on a physical model that accounts for the polyenergetic x-ray source spectrum and the measurement nonlinearities caused by energy-dependent attenuation. Unlike our earlier work, the proposed algorithm does not require pre-segmentation of the object into the various tissue classes (e.g., bone and soft tissue) and allows mixed pixels. The attenuation coefficient of each voxel is modelled as the product of its unknown density and a weighted sum of energy-dependent mass attenuation coefficients. We formulate a penalized-likelihood function for this polyenergetic model and develop an iterative algorithm for estimating the unknown density of each voxel. Applying this method to simulated x-ray CT measurements of objects containing both bone and soft tissue yields images with significantly reduced beam hardening artefacts relative to conventional beam hardening correction methods. We also apply the method to real data acquired from a phantom containing various concentrations of potassium phosphate solution. The algorithm reconstructs an image with accurate density values for the different concentrations, demonstrating its potential for quantitative CT applications. 相似文献
9.
10.
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