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排序方式: 共有776条查询结果,搜索用时 0 毫秒
1.
Rupture of the distal biceps tendon: evaluation with MR imaging 总被引:2,自引:0,他引:2
2.
3.
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
4.
5.
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
6.
7.
KM Kanal NJ Hangiandreou AM Sykes HE Eklund PA Araoz JA Leon BJ Erickson 《Journal of digital imaging》2002,14(1):30-37
The aims of this work were to measure the accuracy of one continuous speech recognition product and dependence on the speaker's
gender and status as a native or nonnative English speaker, and evaluate the product's potential for routine use in transcribing
radiology reports. IBM MedSpeak/Radiology software, version 1.1 was evaluated by 6 speakers. Two were nonnative English speakers,
and 3 were men. Each speaker dictated a set of 12 reports. The reports included neurologic and body imaging examinations performed
with 6 different modalities. The dictated and original report texts were compared, and error rates for overall, significant,
and subtle significant errors were computed. Error rate dependence on modality, native English speaker status, and gender
were evaluated by performing ttests. The overall error rate was 10.3 +/- 3.3%. No difference in accuracy between men and women
was found; however, significant differences were seen for overall and significant errors when comparing native and nonnative
English speakers (P = .009 and P = .008, respectively). The speech recognition software is approximately 90% accurate, and
while practical implementation issues (rather than accuracy) currently limit routine use of this product throughout a radiology
practice, application in niche areas such as the emergency room currently is being pursued. This methodology provides a convenient
way to compare the initial accuracy of different speech recognition products, and changes in accuracy over time, in a detailed
and sensitive manner. 相似文献
8.
The viral transneuronal labeling method was used to demonstrate that orexin-containing neurons of the lateral hypothalamic area (LHA) are linked via multisynaptic connections to different sympathetic outflow systems. Two different types of transneuronal tracing experiments were performed: single- and double-virus studies. In the first series of experiments, Bartha pseudorabies virus (PRV), a retrograde transneuronal tracer, was injected into single sympathetic targets, viz., stellate ganglion, adrenal gland, celiac ganglion, and kidney. Six to 7 days post-injection, orexin (hypocretin) neurons were transneuronally labeled. In a second set of experiments, the double-virus tracing method was used to determine whether single orexin LHA neurons are linked to two different sympathetic outflow systems. Two isogenic forms of Bartha PRV were used that differed by a single gene. beta-Galactosidase Bartha PRV was injected into the stellate ganglion and green fluorescent protein Bartha PRV into the adrenal gland of the same rat. The reverse placement of viral injections was made in another set of rats. In both paradigms, some orexin LHA neurons were transneuronally labeled with both viruses, indicating that they are capable of modulating multiple sympathetic outflow systems. These findings raise the possibility that orexin LHA neurons regulate general sympathetic functions, such as those that occur during arousal or the fight-or-flight response. 相似文献
9.
Subjective tinnitus is a common problem with many etiologies. Objective tinnitus, in which the sound is perceived by both the patient and the examiner, is less common. Objective tinnitus of the vascular type, in which a pulse synchronous bruit is heard by an independent observer, is frequently related to an underlying arterial or arteriovenous malformation, most commonly a dural arteriovenous fistula (DAVF) involving the transverse and sigmoid sinuses. The remaining cases are usually termed "essential" vascular tinnitus, and are presumed to have a venous etiology. In these cases, the audible noise is generally assumed to be produced within the sino-jugular connection, or within an enlarged jugular bulb. We present four documented cases of objective pulse synchronous tinnitus due to focal narrowing (acquired and developmental) of the mid-portion of the transverse dural sinus. In all cases, a bruit was audible directly over a focal constriction in the sinus, demonstrated by cerebral angiography or direct catheter venography. In one case, selective venography revealed a distensible sinus narrowing, associated with a jet of contrast marking fast flow within a developmental sinus segmentation. In another case, a loud pulse synchronous bruit was heard directly over a focal transverse sinus stenosis, which was detected by angiography at the site of a vascular surgical clip. In this case, magnetic resonance (MR) falsely predicted sinus occlusion. In two other cases, an audible bruit was also heard directly overlying a narrowed transverse sinus, seen in the venous phase of angiography. Transverse sinus stenosis is an unappreciated cause of objective pulsatile tinnitus, and we believe that this mechanism may underlie many cases of "essential" or venous etiology tinnitus not otherwise anatomically explained. Non-invasive testing, computed tomography (CT) and MR and non-directed angiography may overlook it. Conventional catheter arteriography or venography should be performed in such cases, with attention to the dural sinuses, if other tests fail to define the anatomic basis of the audible bruit. 相似文献
10.
Gerd Geerling Norbert Koop Andreas Tüngler Ralf Brinkmann Christopher Wirbelauer Reginald Birngruber Horst Laqua 《Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft》1999,96(5):306-311
Purpose: Pulsed holmium lasers are currently used to correct hyperopia by means of laser thermokeratoplasty (LTK). Series of μs laser
pulses are applied with a high repetition rate to induce shrinkage of corneal collagen fibers. The pulsed energy application
results in intrastromal temperature peaks of up to 200 °C. A continuously emitting laser diode can – as we demonstrated recently
in an invivo study on minipigs – be used for LTK and may be of advantage because the temperature rise is more steady. The
aim of this study was to examine the safety, amount, and stability of hyperopic correction of diode LTK on blind human eyes.
Methods: We used a laserdiode that was set to continuously emit light at λ = 1.854 μm/μa = 1.04 mm–1(group I, n = 4) or 1.87 μm/μa = 1.92 mm–1 (group II, n = 4). Radiation energy was 100 to 150 mW for 10 s per coagulation. Eight coagulations on a single ring (group I) and 16 coagulations
on a double ring (group II) diameter were applied in the cornea concentric to the entrance pupil by means of a vacuum-fixed
application mask (group I = conjunctival fixation; group II = corneal fixation) and a handpiece with a focusing optic. Preoperatively
as well as 1 week, 1, 2, 3, 6 12 and 18 months postoperative ophthalmologic controls were performed and the corneal refractive
power was measured.
Results: In group I initial refractive changes of up to + 4.9 D were achieved (1 week postoperative). However, due to the great penetration
depth of the laser irradiation, large endothelial defects resulted beneath the stromal coagulations. In group II an initial
refractive change of up to + 6.8 D was achieved and as a result of the reduced penetration depth, the endothelial cell damage
was much reduced. Partial regression of the refractive effect occured in all subjects, which continued in higher refractive
changes during the 2nd postoperative year. The refractive effect at 12 months was + 0.6 to + 1.5 D in group I and + 0.9 to + 5.7 D in group II.
At 12 months the induced astigmatism was 0.5 to 2.2 D in group I and 0.3 to 1.6 D in group II. No serious adverse effects
were noticed.
Conclusion: A continously emitting laser diode working at a wavelength of 1.87 μm can be used to correct hyperopia by means of LTK safely
and effectively. Regression occurs predominantly in the first 6 postoperative months. Further studies must be conducted to
determine the importance of patient inherent parameters such as age in establishing a nomogram.
相似文献