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Biomedical subjects

Karsten Krueger

Publications and source records attributed to Karsten Krueger.

12 recordsLinked to original sources
PubMed2006

High impact running improves learning.

Regular physical exercise improves cognitive functions and lowers the risk for age-related cognitive decline. Since little is known about the nature and the timing of the underlying mechanisms, we probed whether exercise also has immediate beneficial effects on cognition. Learning performance was assessed directly after high impact anaerobic sprints, low impact aerobic running, or a period of rest in 27 healthy subjects in a randomized cross-over design. Dependent variables comprised learning speed as well as immediate (1 week) and long-term (>8 months) overall success in acquiring a novel vocabulary. Peripheral levels of brain-derived neurotrophic factor (BDNF) and catecholamines (dopamine, epinephrine, norepinephrine) were assessed prior to and after the interventions as well as after learning. We found that vocabulary learning was 20 percent faster after intense physical exercise as compared to the other two conditions. This condition also elicited the strongest increases in BDNF and catecholamine levels. More sustained BDNF levels during learning after intense exercise were related to better short-term learning success, whereas absolute dopamine and epinephrine levels were related to better intermediate (dopamine) and long-term (epinephrine) retentions of the novel vocabulary. Thus, BDNF and two of the catecholamines seem to be mediators by which physical exercise improves learning.

Adult↗
PubMed2005

Endovascular gamma irradiation for the prevention restenosis after angioplasty of femoropopliteal de novo stenoses.

The purpose of this study was to investigate the effectiveness and detect side effects of centered, overlapped endovascular gamma irradiation after angioplasty of de novo femoropopliteal stenoses. Thirty patients (age 65.3+/-9.2 years) with arterial occlusive disease were prospectively enrolled to receive endovascular gamma irradiation (192-iridium, 14 Gy centered at 2 mm vessel wall) immediately after percutaneous transluminal angioplasty (PTA) of femoropopliteal stenoses. Irradiation overlapped dilatation by 1-2 cm at each end. Follow-up involved angiography after 12 months; duplex sonography; and interviews before and after PTA and at 1, 6, and 12 months follow-up. PTA and centered endovascular irradiation were performed successfully in all patients. Three thromboembolic complications occurred during irradiation. Angiographic and clinical follow-up was possible in 28 patients. The angiographic degree of stenosis was 73.8%+/-16.3% before and 3.6%+/-23.5% after PTA and was 3.5%+/-43.7% at the 1-year follow-up. Restenosis (>50%) of the target lesion developed in three patients (10.7%) and edge stenoses (>30%) in nine patients (32.1%). An aneurysm of the irradiated segment in one patient was treated by stenting. The rate of retreatment was 17.9%. The vessel diameter after endovascular gamma irradiation and PTA of femoropopliteal stenoses remained stable. Restenosis, induction of edge stenoses, and aneurysm were reasons for reinterventions.

Aged↗
PubMed2005

Postcatheterization pseudoaneurysm: results of US-guided percutaneous thrombin injection in 240 patients.

PURPOSE: To prospectively evaluate ultrasonographically (US) guided percutaneous thrombin injection for treatment of femoral artery and brachial artery pseudoaneurysms. MATERIALS AND METHODS: The university institutional review board approved the study. Informed consent was obtained from all patients. Two hundred forty patients with postcatheterization femoral artery (n = 132) or brachial artery (n = 8) pseudoaneurysms were treated with US-guided bovine thrombin (1.000 IU/mL) injection. At diagnosis, 107 (44.6%) patients received anticoagulation therapy; 159 (66.2%), antiplatelet therapy; and 76 (31.7%), both therapies. Pseudoaneurysm size, length and width of pseudoaneurysm neck, thrombin dose, therapy outcome, and complications were documented. The peak blood flow in peripheral arteries was determined before and after thrombin injection. Follow-up duplex US was performed 12-24 hours, 5-7 days, and 21-25 days after treatment. A nonpaired t test was used to compare differences in age between the male and female patients. Two-way analysis of covariance was performed to analyze the influences of factors that may have been related to the amount of thrombin used. RESULTS: Mean pseudoaneurysm volume was 4.69 cm3 +/- 5.49 (standard deviation). Simple and complex pseudoaneurysms were treated in 165 and 75 patients, respectively. A total of 260 thrombin injections were performed: 1.04 injections per patient with a simple pseudoaneurysm and 1.17 injections per patient with a complex pseudoaneurysm. The mean injected thrombin dose was 425.31 IU +/- 341.75 for all pseudoaneurysms, 382.12 IU +/- 281.00 for simple pseudoaneurysms only, and 520.33 IU +/- 434.64 for complex pseudoaneurysms only. There was only a computational correlation between pseudoaneurysm size and thrombin dose (r2 = 0.07). The primary success rate was 93.8% overall, 95.8% for simple pseudoaneurysms, and 89% for complex pseudoaneurysms. The secondary success rate was 99.6% overall, 100% for simple pseudoaneurysms, and 99% for complex pseudoaneurysms. Early (at < or =24 hours) reperfusion occurred in one simple and five complex pseudoaneurysms. Four late reperfusions-two in simple and two in complex pseudoaneurysms-were detected at 1-week follow-up; no late reperfusions were detected at 3 weeks. Thromboembolic complications occurred in two patients and resolved spontaneously. One mild allergic reaction and no infections occurred. CONCLUSION: US-guided percutaneous thrombin injection enables successful, safe management of postcatheterization pseudoaneurysms.

Adult↗
PubMed2005

Percutaneous treatment of a splenic artery pseudoaneurysm by thrombin injection.

Pseudoaneurysms in the visceral arteries are rare complications of pancreatitis. In the reported case, a 42-year-old man with a splenic pseudoaneurysm was successfully treated by computed tomography (CT)-guided direct thrombin injection into the pseudoaneurysm lumen. Selective catheterization of the splenic artery had proven technically impossible. During the procedure, contrast medium was injected via a pigtail catheter into the aorta for planning, correct positioning of the needle tip, and control imaging after injection. CT examinations 1 day, 3 weeks, and 6 months after treatment demonstrated complete occlusion shrinkage of the pseudoaneurysm, and the patient was symptom-free.

Adult↗
PubMed2004

De novo femoropopliteal stenoses: endovascular gamma irradiation following angioplasty--angiographic and clinical follow-up in a prospective randomized controlled trial.

PURPOSE: To assess and report the follow-up results of a randomized controlled trial on centered endovascular gamma irradiation performed after percutaneous transluminal angioplasty (PTA) for de novo femoropopliteal stenoses. MATERIALS AND METHODS: Thirty patients who underwent PTA for de novo femoropopliteal stenoses were randomly assigned to undergo 14-Gy centered endovascular irradiation (irradiation group, n = 15) or no irradiation (control group, n = 15). Intraarterial angiography was performed 6, 12, and 24 months after treatment; duplex ultrasonography (US), the day before and after PTA and 1, 3, 6, 9, 12, 18, and 24 months later. Treadmill tests and interviews were performed the day before PTA and 1, 3, 6, 9, 12, 18, and 24 months later. Results of angiography, duplex US, treadmill tests, and interviews were evaluated with the nonpaired t or the Fisher exact test. RESULTS: Baseline characteristics did not differ significantly between the two groups. Mean absolute individual changes in degree of stenosis, compared with the degrees of stenosis shortly after PTA, in the irradiation group versus in the control group were -10.6% +/- 22.3 versus 39.6% +/- 24.6 (P <.001) at 6 months, -2.0% +/- 34.2 versus 40.6% +/- 32.6 (P =.002) at 12 months, and 7.4% +/- 43.2 versus 37.7% +/- 34.5 (P =.043) at 24 months. The rates of target lesion restenosis at 6 (P =.006) and 12 (P =.042) months were significantly lower in the irradiation group. The numbers of target lesion re-treatments were similar between the groups, but target vessel re-treatments were more frequent in the irradiation group. There were no significant differences in interview or treadmill test results between the two groups at t test analysis. CONCLUSION: The degree of stenosis was significantly reduced 6, 12, and 24 months after angioplasty of de novo femoropopliteal stenoses in the patients who underwent endovascular irradiation.

Aged↗
PubMed2004

How thrombus model impacts the in vitro study of interventional thrombectomy procedures.

RATIONALE AND OBJECTIVES: Numerous experimental models are used to investigate the effectiveness of thrombectomy devices. We aimed to study the systematic effects of different in vitro thrombus models on the results of experimental thrombectomy and examined how thrombi formed in vitro and ex vivo differ. METHODS: Three variables involved in human in vitro thrombogenesis were investigated: spontaneous or thrombin-induced clotting, age (1 or 5 days old), and storage temperature (4 degrees C or 21 degrees C). The fibrin content of in vitro and fresh or old ex vivo thrombi was measured by histologic studies. Ten experiments were performed with each of 8 different in vitro thrombus types using (1) ultrasound thrombolysis, (2) Oasis thrombectomy, (3) Amplatz thrombectomy, and (4) Straub-Rotarex catheters. Thrombus weight was measured after standardized treatment. RESULTS: The fibrin content was markedly lower in all in vitro than in fresh and old ex vivo thrombi. In vitro thrombus type had no impact on the effectiveness of ultrasound thrombolysis and Amplatz thrombectomy. Thrombogenesis type affected Oasis and Straub-Rotarex catheter use. Storage temperature had a systematic impact on the outcome of Oasis thrombectomies. CONCLUSION: The fibrin content of in vitro thrombi differs substantially from that of fresh and old ex vivo human thrombi. Experimental conditions may systematically impact experimental evaluation of thrombectomy procedures. In vitro thrombi with thrombin-induced thrombogenesis should be favored for use in thrombectomy experiments.

Catheterization↗
PubMed2002

Aneurysmal re-rupture during selective cerebral angiography.

Two cases of aneurysmal re-rupture during intracranial angiography are presented. This event is accompanied by disastrous consequences with regard to the clinical condition of the patient, as is evident from the cases presented as well as from the literature. Acute alterations of intraluminal pressure as well as a time interval of less than 6 h seems to increase the risk of re-bleeding during angiography. The introduction of and the growing experience with CT and MR angiography may in the near future provide sufficient diagnostic information for surgical planning and thus help to overcome the risk of aneurysmal re-rupture during intra-arterial angiography.

Adult↗
PubMed2002

Protocol of a thromboembolic stroke model in the rat: review of the experimental procedure and comparison of models.

RATIONALE AND OBJECTIVE: Different models to study the pathophysiology of cerebral ischemia and to evaluate therapeutic strategies exist. Described is the detailed procedure of a thromboembolic stroke model in the rat most closely resembling human embolic stroke and compare the model to other equivalent rodent models. MATERIALS AND METHODS: An evaluation of a new thromboembolic stroke model was performed on 35 male Wistar rats. After preparation of the carotid artery, a catheter was introduced into the external carotid artery. During injection of autologous, fibrin-rich emboli into the internal carotid artery the common carotid artery was temporarily occluded. Regional cerebral blood flow (rCBF) and lesion size were determined. RESULTS: Twelve fibrin-rich blood clots of 1.5 mm in length were necessary in order reliably to occlude the origin of the middle cerebral artery. A stable decrease of rCBF and lesion size was confirmed by autoradiography, diffusion, and perfusion MRI, TTC-staining, biochemical imaging, and histology. CONCLUSION: In this animal model, the situation of human cerebral ischemia is simulated closely. The model is suitable for investigations of the pathophysiology of stroke and facilitates studies on the effects of thrombolytic therapy.

Animals↗
PubMed2002

Endovascular gamma irradiation of femoropopliteal de novo stenoses immediately after PTA: interim results of prospective randomized controlled trial.

PURPOSE: To report an interim analysis of whether centered endovascular irradiation with the iridium 192 ((192)Ir) source immediately after percutaneous transluminal angioplasty (PTA) of de novo femoropopliteal stenoses lowers the restenosis rate. MATERIALS AND METHODS: Thirty patients undergoing PTA to treat femoropopliteal stenoses were randomized for prophylaxis against restenosis with centered endovascular irradiation with a (192)Ir source (a dose of 14 Gy 2 mm deep to the vessel wall, irradiation group) or no irradiation (control group). Angiographic follow-up was available for 22 patients at 6 months (irradiation group, n = 10) and 12 patients at 12 months (irradiation group, n = 6). Duplex sonography, treadmill testing, and interviews were performed the day before and the day after PTA and after 1, 3, 6, 9, and 12 months. Results of angiography, duplex sonography, treadmill testing, and interviews were evaluated with a t test and multivariate analysis of variance (clinical characteristics, chi(2) test). RESULTS: Baseline characteristics were comparable in the two groups. Interim analysis of the 6-month follow-up data revealed a trend toward a significantly lower restenosis rate in the irradiation group. The change in the degree of stenosis compared with that after PTA was -14.7% +/- 20.8 (mean +/- SD) in the irradiation group versus 37.7% +/- 27.3 in the control group (P =.001) and became even more marked at 12 months (-9.5% +/- 34.5 vs 45.5% +/- 40.7 [P =.03], respectively). The follow-up results of treadmill testing and interviews showed a nonsignificant benefit for the irradiation group. One thromboembolic complication occurred during irradiation. No side effects were observed during follow-up. CONCLUSION: Endovascular irradiation with a centered (192)Ir source immediately after PTA of de novo femoropopliteal stenoses reduces the restenosis rate.

Angiography, Digital Subtraction↗
PubMedDate not supplied

Centered endovascular irradiation to prevent postangioplasty restenosis of arteriovenous fistula in hemodialysis patients; Results of a feasibility study.

PURPOSE: To report follow-up results of a prospective trial on centered endovascular gamma-irradiation (CEGI) after percutaneous transluminal angioplasty (PTA) for stenosis of arteriovenous fistula in hemodialysis patients. METHODS AND MATERIALS: Eight patients receiving PTA for recurrent (n = 4) or de novo arteriovenous fistula stenoses were treated with CEGI with iridium-192 (14 Gy). Angiography was performed after 6 and 12 months or if problems reoccurred during hemodialysis. Parameters of hemodialysis and duplex sonography were determined the day before and after PTA and after 1, 3, 6, 9, and 12 months. RESULTS: CEGI was performed successfully and without complications in seven patients. In six patients, restenosis occurred 6-52 weeks (mean 20.8 +/- 17.9 weeks) after PTA and required PTA. Parameters of hemodialysis and duplex sonography deteriorated during follow-up. CONCLUSIONS: Centered endovascular gamma-irradiation with iridium 192 immediately after PTA of fistula stenoses was a safe and feasible method but did not prevent restenosis.

Aged↗
PubMedDate not supplied

Endovascular gamma-irradiation to prevent recurrent femoral in-stent restenosis. A case report.

We report about a patient with twice recurrence of femoral in-stent restenoses. Centered endoluminal gamma-irradiation with 192 iridium was performed immediately after the second stent recanalization. The irradiation dose was 14 Gy calculated at 2-mm depth of vessel wall. One-year follow-up demonstrates neither clinical nor angiographic evidence of restenosis.

Arterial Occlusive Diseases↗