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Biomedical subjects

R Drescher

Publications and source records attributed to R Drescher.

12 recordsLinked to original sources
PubMed2006

[Angiographic follow-up after carotid artery stenting of bifurcation stenosis].

PURPOSE: The purpose of this prospective study was to determine the restenosis grade, the intima hyperplasia and the stent expansion via angiographic follow-up six months after carotid artery stenting. MATERIALS AND METHODS: In 100 patients, angiographic follow-up was performed 5.9 months (range: 2.9-11.4 months) after carotid artery stenting. The restenosis grade, the intima hyperplasia and the stent expansion were measured by selective angiography of the treated carotid artery. RESULTS: The mean restenosis grade was 16 % (range: 0-78 %). In 6 of 100 patients (6 %), a restenosis grade of > 50 % was measured. In 4 patients the restenosis grade was 50-70 %. In 2 patients the restenosis grade was > 70 %. In 91 of 100 patients (91 %), the restenosis was localized in the former area of stenosis of the carotid artery, and in 9 of 100 patients (9 %), the restenosis was localized in the cranial stent end. The mean grade of intima hyperplasia was 31 % (range: 2-70 %). The mean increase in stent expansion at the time of follow-up was 10 % (range: 0-59 %). No correlation was able to be determined between the grade of stenosis and the grade of restenosis (rho = 0.017, range: - 0.180-0.213), between the grade of residual stenosis and the grade of restenosis (rho = 0.257, range: 0.064-0.431) and between intima hyperplasia and the grade of restenosis (rho = 0.476, range: 0.309-0.615). CONCLUSIONS: Carotid artery stenting is associated with a low incidence of high-grade restenosis 6 months after an intervention. The intima hyperplasia, which can be observed in each Wallstent, is partly compensated by the expansion of the self-expandable stent. Without a correlation between the grade of residual stenosis and the grade of restenosis, low-grade residual stenosis can be accepted. Therefore, we recommend undersized postdilation of the Wallstent.

Aged↗
PubMed2004

[Direct MR-arthrography of the shoulder with maximum capsular distension for surgical planning].

PURPOSE: To evaluate the effectiveness of direct MR arthrography of the glenohumeral joint with maximum distension of the joint capsule in patients with glenohumeral instability for preoperative diagnosis and for determining the method of surgical intervention. MATERIALS AND METHODS: MR arthrography of the shoulder joint was performed on a 1.5 T system in 38 patients. All patients suffered from anterior or bidirectional instability. Using a fluoroscopically guided posterior approach, a 1 % dilution of dimeglumine gadopentetate (5 mmol Gd-DTPA/l) was injected until full capsular stretching was achieved. MR imaging protocol included fat-saturated transversal, oblique-coronal and oblique-sagittal T1-weighted spin-echo, T1-weighted 3-D and transversal T2-weighted Flash-2D. RESULTS: MR imaging revealed significant capsule distention in 22 patients and ventral capsule defects in 9 patients. Labral lesions were depicted in 25 patients, bicipital tendon lesions in 4 patients and partial ruptures of the rotator cuff in 3 patients. 15 of the 38 patients underwent surgery. Areas of pathologic laxity of the glenohumeral capsule were correctly described in all cases. In 12 of 15 patients, the best method of intervention could be determined prospectively. In 3 of 15 patients, the necessary operation was overestimated. Regarding labral ruptures, MRI had a sensitivity of 88 %, a specificity of 86 %, and a diagnostic accuracy of 87 %. CONCLUSION: Direct glenohumeral MR arthrography allows accurate preoperative evaluation of labral and tendinous structures. Judging the capsular laxity allows the determination of the optimal method of surgical intervention. The maximum extent of a stabilizing operation can be predicted preoperatively.

Adult↗
PubMed2001

[Cerebral protection with balloon occlusion during carotid artery stent implantation--first experiences].

PURPOSE: To assess the technical feasibility and the results of cerebral protection with the GuardWire Plus Temporary Occlusion & Aspiration System during carotid artery stenting for high-grade stenosis. PATIENTS AND METHODS: In 20 patients 20 carotid artery stenoses were treated with stent placement under cerebral protection. A contralateral carotid occlusion was an exclusion criteria for the use of the protection device. In all cases only aspiration, but no flushing was used before deflation of the occlusion balloon. In 17 of 20 patients diffusion-weighted (DW-)MRT imaging of the brain was performed before and 24 hours after the procedure. RESULTS: The stent implantation was successfully performed in all patients. In 3 patients neurologic symptoms occurred during the occlusion time. In these 3 patients the symptoms immediately disappeared after deflation of the balloon. In one case there was dilatation of the internal carotid artery at the site of the balloon inflation. In 3 of the 17 DW-MR images new ipsilateral cerebral lesions, in one case a new contralateral lesion occurred after the procedure. CONCLUSIONS: The cerebral protection procedure is technically feasible. The occlusion of the internal carotid artery was not tolerated by all patients. The DW-MR imaging demonstrated cerebral lesions indicating the occurrence of cerebral microemboli during the procedure. Further investigations are necessary to determine if the use of the cerebral protection device will improve the results of the carotid artery stenting for high-grade stenoses.

Aged↗
PubMed2001

Diffusion-weighted MR imaging after angioplasty or angioplasty plus stenting of arteries supplying the brain.

BACKGROUND AND PURPOSE: There has been concern regarding the safety of revascularization procedures of vessels supplying the brain vessels because of the risk of cerebral embolization during the procedure. We have observed a high incidence of hyperintense lesions on diffusion-weighted MR images of the brain after stenting at the carotid bifurcation. The hypothesis of this study is that diffusion-weighted MR imaging of the brain can reveal new diffusion abnormalities after angioplasty or angioplasty plus stenting of arteries supplying the brain, other than at the carotid bifurcation. Therefore, we prospectively obtained diffusion-weighted MR images of the brain before and after such revascularization procedures. METHODS: Thirty-seven revascularization procedures were performed in 32 patients. Eleven interventions were performed at the distal internal carotid artery, two at the external carotid artery, two at the common carotid artery, five at the innominate artery, five at the vertebral artery, and 12 at the proximal subclavian artery. Diffusion-weighted MR imaging of the brain was performed before and 24 hours after the procedures. RESULTS: After eight (22%) of 37 procedures, new hyperintensities were visible on the diffusion-weighted MR images. With six of these eight procedures, the hyperintensities occurred in the vascular territory supplied by the treated vessel. In total, 35 new cerebral lesions could be seen, 33 (94%) of which occurred in the vascular territory supplied by the treated vessel. None of the patients in whom new diffusion abnormalities were found had new neurologic symptoms or deficits. No new lesions could be seen after procedures at the subclavian artery. CONCLUSION: Revascularization procedures of arteries supplying the brain were associated with new lesions on the diffusion-weighted MR images of the brain after 22% of the procedures, provided that MR imaging could be performed, indicating the occurrence of cerebral microemboli during such procedures. Diffusion-weighted MR imaging of the brain can be used as a tool to assess the impact of modifications of procedural technique and/or the use of cerebral protection devices on the occurrence of such lesions.

Adult↗
PubMed2000

An additional transcript of the cdc25C gene from A431 cells encodes a functional protein.

Human p53 protein was found to be functional in fission yeast in terms of growth repression and checkpoint control. Expression of wild-type p53 or the hot spot mutant p53His273 results in dramatic morphological changes and loss of viability of recipient yeast cells. Overexpression of cdc25C phosphatase, the mitotic activator of cdc2, results in suppression of a p53-induced growth arrest. In order to understand the interplay between p53 and cdc25C in mammalian cells we isolated and sequenced cdc25C cDNA from the epidermoid carcinoma cell line A431, which is known to carry the p53His273 mutation. Two different transcripts of the human cdc25C gene were detected by RT-PCR analysis - one full-length transcript and a shortened version (cdc25Cdm) that carries two deletions in the 5'-region of the gene. In normal human skin fibroblasts only one full-length cdc25C transcript was detected. The two different transcripts code for proteins with a molecular weight of 55 kDa and 46 kDa, respectively. Both cdc25C cDNAs from A431 cells were found to complement a conditional lethal cdc25.22 mutant strain as well as a cdc25 deletion strain of Schizosaccharomyces pombe indicating that functional proteins were translated. Expression of cdc25Cdm variant leads to a stronger uncoupling of DNA replication from mitosis than expression of cdc25C suggesting that the deletion within the amino-terminus of cdc25C leads to a protein which might contribute some potential for oncogenic transformation. As with cdc25C, uncoupling of the DNA synthesis checkpoint by cdc25Cdm was reversed by coexpression of wild-type p53.

Alternative Splicing↗
PubMed1997

Human p53 restores DNA synthesis control in fission yeast.

The p53 gene is the most common target for genetic alterations in human cancers. As a transcriptional regulator p53 enhances the expression of proteins that control cellular proliferation. Although there is no evidence of a p53 homologous gene in yeast, the p53 protein was found to be functional in terms of growth repression and transactivation in yeast, suggesting that some features of p53 function are conserved. Here we report the construction and characterization of a p53 wild type expression strain of fission yeast. Upon induction of wild type p53 expression a dosage dependent growth arrest was observed rendering recipient yeast cells sensitive to UV irradiation in a p53 dosage dependent fashion. The observed growth arrest was efficiently suppressed by coexpression of human CDC25C phosphatase, which restored a normal resistance to UV irradiation in p53 and CDC25C coexpressing yeast cells. Furthermore, expression of CDC25C alone inactivated the DNA synthesis control whereas p53 and CDC25C coexpressing yeast cells showed an intact checkpoint control. Upon moderate expression of wild type p53 a restoration of the DNA synthesis control was also observed in a cdc2.3w mutant background, whereas a tumor mutant of p53 failed to restore this important checkpoint in fission yeast.

Cell Cycle Proteins↗
PubMedDate not supplied

Superior mesenteric artery aneurysm stent graft.

Visceral artery aneurysms represent 0.1% to 0.2% of all vascular aneurysms. They are mostly asymptomatic, but rupture is associated with a high mortality rate. We present a case of an asymptomatic aneurysm of the proximal superior mesenteric artery in a 64-year-old man that was successfully treated by implantation of a covered stent graft. The use of endovascular techniques to manage visceral artery aneurysms should be considered.

Aneurysm↗
PubMedDate not supplied

Clinical results of cerebral protection with a filter device during stent implantation of the carotid artery.

PURPOSE: To assess the technical feasibility and the clinical results of cerebral protection with the Angioguard emboli-capture guidewire system during carotid artery stenting (CAS) for high-grade stenoses. METHODS: In 20 patients 20 stenoses of the internal carotid artery were treated with stent implantation. In all patients diffusion-weighted (DW) magnetic resonance imaging (MRI) of the brain was performed before and 24 hr after the procedure. RESULTS: The filter device was effectively employed during all steps of the procedure in 16 of 20 patients, in two only postdilation could be protected, and in two no protection was possible. After three of the 20 procedures new ipsilateral cerebral lesions were visualized by DW-MRI. No new permanent neurologic deficits occurred. CONCLUSION: Cerebral protection with the filter device is technically feasible in most cases. DW-MRI demonstrated new cerebral lesions indicating the occurrence of cerebral microemboli during the protected procedures. Further investigations are necessary to determine whether the use of the cerebral protection device will improve the results of CAS.

Aged↗