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Weller JM, Dorn F, Meissner JN, Stösser S, Beckonert NM, Nordsiek J, Kindler C, Riegler C, Keil F, Petzold GC, Bode FJ, Reich A, Nikoubashman O, Röther J, Eckert B, Braun M, Hamann GF, Siebert E, Nolte CH, Bohner G, Eckert RM, Borggrefe J, Schellinger P, Berrouschot J, Bormann A, Kraemer C, Leischner H, Petersen M, Stögbauer F, Boeck-Behrens T, Wunderlich S, Ludolph A, Henn KH, Gerloff C, Fiehler J, Thomalla G, Alegiani A, Schäfer JH, Tiedt S, Kellert L, Trumm C, Ernemann U, Poli S, Liman J, Ernst M, Gröschel K, Uphaus T. Antithrombotic treatment and outcome after endovascular treatment and acute carotid artery stenting in stroke patients with atrial fibrillation. Neurol Res Pract 2022; 4:42. [PMID: 36089621 PMCID: PMC9465921 DOI: 10.1186/s42466-022-00207-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 07/22/2022] [Indexed: 11/18/2022] Open
Abstract
Background Oral anticoagulation (OAC) is the mainstay of secondary prevention in ischemic stroke patients with atrial fibrillation (AF). However, in AF patients with large vessel occlusion stroke treated by endovascular therapy (ET) and acute carotid artery stenting (CAS), the optimal antithrombotic medication remains unclear.
Methods This is a subgroup analysis of the German Stroke Registry—Endovascular Treatment (GSR-ET), a prospective multicenter cohort of patients with large vessel occlusion stroke undergoing ET. Patients with AF and CAS during ET were included. We analyzed baseline and periprocedural characteristics, antithrombotic strategies and functional outcome at 90 days. Results Among 6635 patients in the registry, a total of 82 patients (1.2%, age 77.9 ± 8.0 years, 39% female) with AF and extracranial CAS during ET were included. Antithrombotic medication at admission, during ET, postprocedural and at discharge was highly variable and overall mortality in hospital (21%) and at 90 days (39%) was high. Among discharged patients (n = 65), most frequent antithrombotic regimes were dual antiplatelet therapy (DAPT, 37%), single APT + OAC (25%) and DAPT + OAC (20%). Comparing DAPT to single or dual APT + OAC, clinical characteristics at discharge were similar (median NIHSS 7.5 [interquartile range, 3–10.5] vs 7 [4–11], p = 0.73, mRS 4 [IQR 3–4] vs. 4 [IQR 3–5], p = 0.79), but 90-day mortality was higher without OAC (32 vs 4%, p = 0.02). Conclusions In AF patients who underwent ET and CAS, 90-day mortality was higher in patients not receiving OAC. Registration: https://www.clinicaltrials.gov; Unique identifier: NCT03356392. Supplementary Information The online version contains supplementary material available at 10.1186/s42466-022-00207-7.
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Goertz L, Liebig T, Siebert E, Özpeynirci Y, Pennig L, Celik E, Schlamann M, Dorn F, Kabbasch C. Treatment of Proximal Posterior Inferior Cerebellar Artery Aneurysms by Intrasaccular Flow Disruption: A Multicenter Experience. AJNR Am J Neuroradiol 2022; 43:1158-1163. [PMID: 35863779 PMCID: PMC9575426 DOI: 10.3174/ajnr.a7566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 05/12/2022] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Treatment of PICA aneurysms can be technically challenging by either surgical or endovascular means. Our aim was to report our preliminary experience with intrasaccular flow disruption using the Woven EndoBridge (WEB) for the treatment of proximal PICA aneurysms. MATERIALS AND METHODS Sixteen PICA aneurysms treated with the WEB at 3 institutions were retrospectively reviewed. Baseline patient and aneurysm characteristics, procedural specifics, clinical outcomes, and angiographic results were evaluated. RESULTS All aneurysms were located at the proximal, anteromedullary segment of the PICA. Seven aneurysms were ruptured. The median aneurysm size was 3.9 mm (range, 2-12 mm), and all aneurysms were wide-neck. WEB deployment failed in 1 case due to WEB protrusion in a small PICA aneurysm. Additional stent implantation was required for 2 aneurysms to improve intra-aneurysmal WEB positioning. One patient developed a partial posterior cerebral artery territory infarction with transient hemianopsia. Intraoperative rerupture of a ruptured aneurysm could be immediately stopped by WEB deployment due to intrasaccular stasis; however, it might have contributed to a slight disability of the patient. At last angiographic follow-up, 12/15 aneurysms (80%) were completely occluded and 3/15 (20%) had a neck remnant. CONCLUSIONS The preliminary results indicate that WEB treatment of proximal PICA aneurysms is feasible with a reasonable safety and efficacy profile. The advantages of intrasaccular flow disruption include preservation of the PICA, durable aneurysm occlusion, and omission of antiplatelet therapy. The low-profile WEB 17 delivery system might enable navigation to distal PICA aneurysms, which needs to be addressed further.
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Affiliation(s)
- L Goertz
- From the Department of Radiology and Neuroradiology (L.G., L.P., E.C., M.S., C.K.), University of Cologne, Faculty of Medicine, University Hospital Cologne, Cologne, Germany
| | - T Liebig
- Department of Neuroradiology (T.L., Y.Ö.), University Hospital Munich, Munich, Germany
| | - E Siebert
- Department of Neuroradiology (E.S.), University Hospital of Berlin (Charité), Berlin, Germany
| | - Y Özpeynirci
- Department of Neuroradiology (T.L., Y.Ö.), University Hospital Munich, Munich, Germany
| | - L Pennig
- From the Department of Radiology and Neuroradiology (L.G., L.P., E.C., M.S., C.K.), University of Cologne, Faculty of Medicine, University Hospital Cologne, Cologne, Germany
| | - E Celik
- From the Department of Radiology and Neuroradiology (L.G., L.P., E.C., M.S., C.K.), University of Cologne, Faculty of Medicine, University Hospital Cologne, Cologne, Germany
| | - M Schlamann
- From the Department of Radiology and Neuroradiology (L.G., L.P., E.C., M.S., C.K.), University of Cologne, Faculty of Medicine, University Hospital Cologne, Cologne, Germany
| | - F Dorn
- Department of Neuroradiology (F.D.), University Hospital Bonn, Bonn, Germany
| | - C Kabbasch
- From the Department of Radiology and Neuroradiology (L.G., L.P., E.C., M.S., C.K.), University of Cologne, Faculty of Medicine, University Hospital Cologne, Cologne, Germany
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Danyel LA, Miszczuk M, Connolly F, Villringer K, Bohner G, Rossel-Zemkouo M, Siebert E. Time Course and Clinical Correlates of Retinal Diffusion Restrictions in Acute Central Retinal Artery Occlusion. AJNR Am J Neuroradiol 2021; 42:1661-1666. [PMID: 34266868 DOI: 10.3174/ajnr.a7201] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 04/04/2021] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND PURPOSE Retinal diffusion restrictions were recently identified as a regular finding in acute central retinal artery occlusion. We sought to investigate the influence of technical MR imaging and clinical parameters on the detection rate of retinal diffusion restrictions on standard brain DWI. MATERIALS AND METHODS In this retrospective cohort study, MR imaging scans of patients with central retinal artery occlusion were assessed by 2 readers for retinal diffusion restrictions on DWI performed within 2 weeks after vision loss. The influence of clinical and technical MR imaging parameters and the time interval between symptom onset and DWI on the presence of retinal diffusion restrictions were evaluated. RESULTS One hundred twenty-seven patients (mean age, 69.6 [SD 13.9] years; 59 women) and 131 DWI scans were included. Overall, the MR imaging sensitivity of retinal diffusion restrictions in acute central retinal artery occlusion was 62.6%-67.2%. Interrater and intrarater agreement for retinal diffusion restrictions was "substantial" with κinter = 0.70 (95% CI, 0.57-0.83) and κintra = 0.75 (95% CI, 0.63-0.88). Detection of retinal diffusion restrictions did not differ with differences in field strengths (1.5 versus 3T, P = .35) or sequence type (P = .22). Retinal diffusion restrictions were consistently identified within the first week with a peak sensitivity of 79% in DWI performed within 24 hours after symptom onset. Sensitivity of retinal diffusion restrictions declined in the second week (10.0%, P < .001). Absence of retinal diffusion restrictions was more prevalent in patients without fundoscopic retinal edema (60% versus 27.1%, P = .004) and with restitution of visual acuity at discharge (75% versus 28.4%, P = .006). CONCLUSIONS Retinal diffusion restrictions in acute central retinal artery occlusion can be reliably identified on DWI performed within 24 hours and 1 week after onset of visual impairment. Detectability of retinal diffusion restrictions is dependent on the clinical course of the disease.
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Affiliation(s)
- L A Danyel
- From the Department of Neurology (L.A.D., F.C.)
| | - M Miszczuk
- Institute for Neuroradiology (M.M., G.B., E.S.)
| | - F Connolly
- From the Department of Neurology (L.A.D., F.C.)
| | | | - G Bohner
- Institute for Neuroradiology (M.M., G.B., E.S.)
| | - M Rossel-Zemkouo
- Department of Ophthalmology (M.R.-Z.), Charité-Universitätsmedizin, Berlin, Germany
| | - E Siebert
- Institute for Neuroradiology (M.M., G.B., E.S.)
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Miszczuk M, Bauknecht H, Kleine J, Liebig T, Bohner G, Siebert E. Direct Puncture of the Carotid Artery as a Bailout Vascular Access Technique for Mechanical Thrombectomy in Acute Ischemic Stroke—The Revival of an Old Technique in a Modern Setting. J Vasc Surg 2020. [DOI: 10.1016/j.jvs.2020.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Tiedt S, Herzberg M, Küpper C, Feil K, Kellert L, Dorn F, Liebig T, Alegiani A, Dichgans M, Wollenweber FA, Alber B, Bangard C, Berrouschot J, Bode F, Boeckh-Behrens T, Bohner G, Bormann A, Braun M, Eckert B, Fiehler J, Flottmann F, Gerloff C, Hamann G, Henn K, Kastrup A, Kraemer C, Krause L, Lehm M, Liman J, Lowens S, Mpotsaris A, Nolte C, Papanagiotou P, Petersen M, Petzold G, Pfeilschifter W, Psychogios M, Reich A, von Rennenberg R, Röther J, Schäfer J, Siebert E, Siedow A, Solymosi L, Thomalla G, Thonke S, Wagner M, Wunderlich S, Zweynert S. Stroke Etiology Modifies the Effect of Endovascular Treatment in Acute Stroke. Stroke 2020; 51:1014-1016. [DOI: 10.1161/strokeaha.119.028383] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background and Purpose—
Stroke etiology drives thrombus composition. We thus hypothesized that endovascular treatment shows different efficacy in cardioembolic versus noncardioembolic large-vessel occlusions (LVOs).
Methods—
Procedural characteristics, grade of reperfusion, and functional outcome at discharge and 90 days were compared between patients with cardioembolic versus noncardioembolic LVO from the GSR-ET (German Stroke Registry–Endovascular Treatment; n=2589). To determine associations with functional outcome, adjusted odds ratios and 95% CIs were calculated using ordinal multivariable logistic regression models adjusting for potential baseline confounder variables.
Results—
Endovascular treatment of cardioembolic LVO had a higher rate of successful reperfusion (85.6% versus 81.0%;
P
=0.002) and a higher rate of complete reperfusion after a single thrombectomy pass (45.7% versus 38.1%;
P
<0.001) compared with noncardioembolic LVO. Cardioembolic LVO was associated with better functional outcome at discharge (adjusted odds ratio, 1.61 [95% CI, 1.37–1.88]) and 90 days (adjusted odds ratio, 1.29 [95% CI, 1.09–1.53]). In mediation analysis, reperfusion explained 47% of the effect of etiology on functional outcome at discharge.
Conclusions—
These results provide evidence for higher efficacy of endovascular treatment in cardioembolic LVO compared with noncardioembolic LVO.
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Affiliation(s)
- Steffen Tiedt
- From the Institute for Stroke and Dementia Research (S.T., M.D., F.A.W.), University Hospital, LMU Munich, Germany
| | - Moriz Herzberg
- From the Institute for Stroke and Dementia Research (S.T., M.D., F.A.W.), University Hospital, LMU Munich, Germany
- Institute of Neuroradiology (M.H., F.D., T.L.), University Hospital, LMU Munich, Germany
| | - Clemens Küpper
- Department of Neurology (C.K., K.F., L.K., F.A.W.), University Hospital, LMU Munich, Germany
| | - Katharina Feil
- Department of Neurology (C.K., K.F., L.K., F.A.W.), University Hospital, LMU Munich, Germany
| | - Lars Kellert
- Department of Neurology (C.K., K.F., L.K., F.A.W.), University Hospital, LMU Munich, Germany
| | - Franziska Dorn
- Institute of Neuroradiology (M.H., F.D., T.L.), University Hospital, LMU Munich, Germany
| | - Thomas Liebig
- Institute of Neuroradiology (M.H., F.D., T.L.), University Hospital, LMU Munich, Germany
| | - Anna Alegiani
- Department of Neurology, University Medical Center Hamburg-Eppendorf, Germany (A.A.)
| | | | - Frank A. Wollenweber
- From the Institute for Stroke and Dementia Research (S.T., M.D., F.A.W.), University Hospital, LMU Munich, Germany
- Department of Neurology (C.K., K.F., L.K., F.A.W.), University Hospital, LMU Munich, Germany
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Goertz L, Liebig T, Siebert E, Herzberg M, Pennig L, Schlamann M, Borggrefe J, Krischek B, Dorn F, Kabbasch C. Low-Profile Intra-Aneurysmal Flow Disruptor WEB 17 versus WEB Predecessor Systems for Treatment of Small Intracranial Aneurysms: Comparative Analysis of Procedural Safety and Feasibility. AJNR Am J Neuroradiol 2019; 40:1766-1772. [PMID: 31488499 DOI: 10.3174/ajnr.a6183] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 07/14/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND PURPOSE The Woven EndoBridge 17 has recently been introduced to the market for facilitated endovascular treatment of small bifurcation aneurysms (≤7 mm) with low-profile microcatheters. We compared the Woven EndoBridge 17 with its predecessor versions in terms of procedural safety and feasibility. MATERIALS AND METHODS This was a multicenter review of aneurysms ranging from 3 to 7 mm treated with the Woven EndoBridge between 2011 and 2019. Aneurysm characteristics, procedural parameters, and complications were retrospectively compared between treatment with the Woven EndoBridge 17 and a control group that was treated with its predecessor versions, using inverse probability of treatment weighting. RESULTS Thirty-eight aneurysms treated with a Woven EndoBridge 17 (mean size, 4.9 ± 1.5 mm) and 70 treated with a predecessor version of the Woven EndoBridge 17 (mean size, 5.6 ± 1.4 mm) were included. The predecessor version of the Woven EndoBridge 17 had a higher failure rate (10.3%) than the Woven EndoBridge 17 (0%, P = .05). Additional stent placement was performed more often with the predecessor version of the Woven EndoBridge 17 (10.0%) than with the Woven EndoBridge 17 (2.6%, adjusted P = .005). The predecessor version of the Woven EndoBridge 17 was associated with a higher thromboembolic event rate (14.3%) than the Woven EndoBridge 17 (5.3%, adjusted P = .002). Neurologic complications (Woven EndoBridge 17: 2.6%; predecessor version of the Woven EndoBridge 17: 2.9%, adjusted P = 1.0) and immediate complete aneurysm occlusion rates (Woven EndoBridge 17: 57.9%; predecessor version of the Woven EndoBridge 17: 54.3%, adjusted P = .21) did not differ significantly between groups. CONCLUSIONS In the current study, the Woven EndoBridge 17 was associated with a potentially lower thromboembolic event rate than the predecessor version of the Woven EndoBridge 17, without compromising the immediate aneurysm occlusion rate. Long-term clinical and angiographic outcome analysis will be necessary to draw a definite conclusion.
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Affiliation(s)
- L Goertz
- From the Department of Neuroradiology (L.G., L.P., M.S., J.B., C.K.), University Hospital of Cologne, Cologne, Germany .,Center for Neurosurgery (L.G., B.K.), University of Cologne, Faculty of Medicine and University Hospital, Cologne, Germany
| | - T Liebig
- Department of Neuroradiology (T.L., M.H., F.D.), University Hospital Munich, Munich, Germany
| | - E Siebert
- Department of Neuroradiology (E.S.), University Hospital of Berlin (Charité), Berlin, Germany
| | - M Herzberg
- Department of Neuroradiology (T.L., M.H., F.D.), University Hospital Munich, Munich, Germany
| | - L Pennig
- From the Department of Neuroradiology (L.G., L.P., M.S., J.B., C.K.), University Hospital of Cologne, Cologne, Germany
| | - M Schlamann
- From the Department of Neuroradiology (L.G., L.P., M.S., J.B., C.K.), University Hospital of Cologne, Cologne, Germany
| | - J Borggrefe
- From the Department of Neuroradiology (L.G., L.P., M.S., J.B., C.K.), University Hospital of Cologne, Cologne, Germany
| | - B Krischek
- Center for Neurosurgery (L.G., B.K.), University of Cologne, Faculty of Medicine and University Hospital, Cologne, Germany
| | - F Dorn
- Department of Neuroradiology (T.L., M.H., F.D.), University Hospital Munich, Munich, Germany
| | - C Kabbasch
- From the Department of Neuroradiology (L.G., L.P., M.S., J.B., C.K.), University Hospital of Cologne, Cologne, Germany
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Tezyk V, Rossignol C, Sergent N, Djurado E, Laurencin J, Siebert E. Cyclic voltammetry and high-frequency series resistance of La0.6Sr0.4Co0.2Fe0.8O3-δ electrode deposited on GDC: Effect of the electrode microstructure and the oxygen partial pressure. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2019.02.066] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Laurencin J, Hubert M, Sanchez DF, Pylypko S, Morales M, Morata A, Morel B, Montinaro D, Lefebvre-Joud F, Siebert E. Degradation mechanism of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ /Gd 0.1 Ce 0.9 O 2-δ composite electrode operated under solid oxide electrolysis and fuel cell conditions. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.05.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Laurencin J, Hubert M, Couturier K, Bihan TL, Cloetens P, Lefebvre-Joud F, Siebert E. Reactive Mechanisms of LSCF Single-Phase and LSCF-CGO Composite Electrodes Operated in Anodic and Cathodic Polarisations. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2015.06.080] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Liman TG, Bohner G, Endres M, Siebert E. Discharge status and in-hospital mortality in posterior reversible encephalopathy syndrome. Acta Neurol Scand 2014; 130:34-9. [PMID: 24329761 DOI: 10.1111/ane.12213] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2013] [Indexed: 11/30/2022]
Abstract
BACKGROUND Posterior reversible encephalopathy syndrome is a serious and increasingly recognized disorder, but data from observational studies on outcome and mortality in posterior reversible encephalopathy syndrome (PRES) are scarce. We aimed to determine the frequency and associations of in-hospital death and discharge status in a large cohort of patients with PRES. METHOD We retrospectively reviewed the radiological report databases of our university hospitals between January 1999 and March 2011 for patients with PRES. Patients fulfilling the criteria for PRES after detailed investigation of clinical charts and imaging studies were included. Clinical charts, paraclinical and brain imaging data at onset as well as available data on in-hospital mortality and discharge status were analyzed. RESULTS A total of 103 patients were included. Five (4.8%) patients died during hospital stay, 27 (26.2%) remained hospitalized after discharge. In univariate analyses, significant differences were found between patients discharged home from hospital and patients referred to rehabilitation or who died in hospital for the following variables: severe edema (P = 0.013), etiology of PRES (P = 0.001), altered mental state at onset (P = 0.003), altered coagulation (P = 0.004), and length of hospital stay >30 days (P < 0.001). CONCLUSION Features of a severe course of PRES such as severe edema and altered mental state are significantly more frequent in patients who were referred to inpatient rehabilitation or died in hospital. Prospective studies are warranted to establish factors that are associated with unfavorable outcome in PRES.
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Affiliation(s)
- T. G. Liman
- Department of Neurology; Charité - Universitätsmedizin Berlin; Berlin Germany
- Center for Stroke Research Berlin; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - G. Bohner
- Department of Neuroradiology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - M. Endres
- Department of Neurology; Charité - Universitätsmedizin Berlin; Berlin Germany
- Center for Stroke Research Berlin; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - E. Siebert
- Department of Neuroradiology; Charité - Universitätsmedizin Berlin; Berlin Germany
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Siebert E, Spors B, Bohner G, Endres M, Liman TG. Posterior reversible encephalopathy syndrome in children: radiological and clinical findings - a retrospective analysis of a German tertiary care center. Eur J Paediatr Neurol 2013. [PMID: 22954513 DOI: 10.1016/j.ejpn.2012.08.003s1090-3798(12)00189-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
PURPOSE To report the radiological and clinical spectrum of posterior reversible encephalopathy syndrome (PRES) in children in a German tertiary referral center. METHODS The radiological report data bases of the authors' university hospitals were searched for paediatric patients with PRES. Clinical and paraclinical data as well as various imaging features at symptom onset and during follow-up were tabulated in patients fulfilling the criteria for PRES. RESULTS A total of 18 paediatric patients with PRES were included into the study. Mean age was 9 years (IQR 7-12), 38.9% were females. Most frequent predisposing causes were renal and haemato-oncologic diseases frequently associated with endotheliotoxic cytostatic medication. Frontal lesions occurred as frequently as parietal lesions followed by occipital lesions. The superior frontal sulcus topographic lesion pattern occurred as frequent as the parieto-occipital one. In 38% of cases residual lesions were encountered with focal laminar necroses being most frequent. Initial clinical syndromes associated with PRES included seizures in 18, altered mental state in 5, and hemiparesis and visual disturbances in 2 children. Mean arterial blood pressure at onset of PRES was 140/85 mmHg (IQR systolic: 124-169, diastolic: 78-93 mmHg). CONCLUSION Paediatric PRES in this cohort comprises a broad radiological and clinical spectrum. The occurrence of frontal lesions, a superior frontal sulcus associated lesion pattern, and the development of focal laminar necrosis appear to be frequent in children.
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Affiliation(s)
- E Siebert
- Department of Neuroradiology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
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Liman TG, Bohner G, Heuschmann PU, Scheel M, Endres M, Siebert E. Clinical and radiological differences in posterior reversible encephalopathy syndrome between patients with preeclampsia-eclampsia and other predisposing diseases. Eur J Neurol 2012; 19:935-43. [DOI: 10.1111/j.1468-1331.2011.03629.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Liman TG, Bohner G, Heuschmann PU, Endres M, Siebert E. The clinical and radiological spectrum of posterior reversible encephalopathy syndrome: the retrospective Berlin PRES study. J Neurol 2011; 259:155-64. [DOI: 10.1007/s00415-011-6152-4] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 06/15/2011] [Indexed: 10/18/2022]
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Katchanov J, Siebert E, Klingebiel R, Endres M. Infectious vasculopathy of intracranial large- and medium-sized vessels in neurological intensive care unit: a clinico-radiological study. Neurocrit Care 2010; 12:369-74. [PMID: 20146025 DOI: 10.1007/s12028-010-9335-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Infections are a well-known cause of cerebral vasculopathy and vasculitis. We aimed to analyze the frequency of intracranial vasculopathy attributable to infection, the spectrum of causative microorganisms, imaging, and cerebrospinal fluid (CSF) characteristics as well as clinical course and outcome. METHODS We used our institution's medical record system to identify all patients diagnosed with nonatherosclerotic central nervous system vasculopathy from January 1, 1999 through February 28, 2009. We reviewed their clinical charts, imaging data, and results of CSF studies. RESULTS Twenty-five adult patients with nonatherosclerotic cerebral vasculopathy of large- and medium-sized intracranial vessels were identified. Eight patients had vasculopathy attributable to infection (32%). The underlying pathologies were acute bacterial meningitis (n = 4), varicella zoster virus (VZV) infection (n = 2), borreliosis (n = 1), and syphilis (n = 1). In six patients, magnetic resonance angiography was performed and showed vasculopathic changes in all patients examined (100%). In both patients with VZV-associated vasculopathy, the arterial wall enhanced on magnetic resonance imaging. The CSF examination of the patients with infectious vasculopathy showed a significantly higher white blood cell count. The outcome of the infectious cohort was unfavorable with one death, two patients with locked-in syndrome, and five patients discharged from intensive care with severe neurological deficits. CONCLUSION In this cohort, one-third of all cases of nonatherosclerotic vasculopathy were due to infectious vasculopathy of large and medium intracranial vessels.
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Affiliation(s)
- J Katchanov
- Department of Neurology, Charité-Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Germany.
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Bauknecht HC, Siebert E, Dannenberg A, Bohner G, Jach C, Diekmann S, Scheurig C, Klingebiel R. Image quality and radiation exposure in 320-row temporal bone computed tomography. Dentomaxillofac Radiol 2010; 39:199-206. [PMID: 20395460 DOI: 10.1259/dmfr/14139527] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES The aim was to define image quality and radiation exposure in the recently introduced 320-row CT of the temporal bone (tb) in comparison to a 16-row tb CT. METHODS A cadaveric head phantom was used for repeated tb volume CT studies (80-120 kV, 25-150 mAs), performed in a 320-row scanner (single rotation, 0.5 mm slice thickness, kernel FC 51) in comparison to 16-row helical CT using standard acquisition parameters (SAP) of 120 kV and 75 mAs (kernel FC 53). Qualitative image evaluation was performed by two radiologists using a 5-point visual analogue scale. Image noise (D(SD)) was determined by region of interest (ROI) based measurements in cadaveric as well as water phantom studies. Dosimetric measurements of the effective dose (ED) and organ dose (OD) of the lens were performed. RESULTS Image quality of 320-row tb CT was equivalent to 16-row CT for SAP scans, resulting in image noise levels (D(SD) 16-/320-row) of 109/237 and 206/446 for air and bone respectively. D(SD) differences were predominantly (>90%) attributable to the different kernels available for tb studies in 16- and 320-row CT. Radiation exposure for 16-/320-row SAP scans amounted to 0.36/0.30 mSv (ED) and 10.0/8.4 mGy (lens dose). CONCLUSION 320-row volume acquisition in tb CT delivers equivalent image quality to 16-row CT while decreasing radiation exposure figures by one sixth. Image noise increase in 320-row CT is negligible with respect to image quality.
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Affiliation(s)
- H C Bauknecht
- Department of Neuroradiology, Chariteplatz 1, Berlin, Germany.
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Diekmann S, Siebert E, Juran R, Roll M, Deeg W, Bauknecht HC, Diekmann F, Klingebiel R, Bohner G. Dose exposure of patients undergoing comprehensive stroke imaging by multidetector-row CT: comparison of 320-detector row and 64-detector row CT scanners. AJNR Am J Neuroradiol 2010; 31:1003-9. [PMID: 20110373 DOI: 10.3174/ajnr.a1971] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND AND PURPOSE Recently introduced 320-detector row CT enables whole brain perfusion imaging compared to a limited scanning area in 64-detector row CT. Our aim was to evaluate patient radiation exposure in comprehensive stroke imaging by using multidetector row CT consisting of standard CT of the head, CTA of cerebral and cervical vessels, and CTP. MATERIAL AND METHODS Organ doses were measured by using LiF-TLDs located at several organ sites in an Alderson-Rando phantom. Effective doses were derived from these measurements. Stroke protocols including noncontrast head CT, CTA of cerebral and cervical vessels, and CTP were performed on 320- and 64-detector row scanners. RESULTS Measured effective doses for the different scanning protocols ranged between 1.61 and 4.56 mSv, resulting in an effective dose for complete stroke imaging of 7.52/7.54 mSv (m/f) for 64-detector row CT and 10.56/10.6 mSv (m/f) for 320-detector row CT. The highest organ doses within the area of the primary beam were measured in the skin (92 mGy) and cerebral hemispheres (69.91 mGy). Use of an eye-protection device resulted in a 54% decrease of the lens dose measured for the combo protocol for whole-brain perfusion with the 320-detector row CT scanner. CONCLUSIONS Phantom measurements indicate that comprehensive stroke imaging with multidetector row CT may result in effective radiation doses from 7.52 mSv (64-detector row CT) to 10.6 mSv (320-detector row CT). The technique of 320-detector row CT offers additional information on the time course of vascular enhancement and whole-brain perfusion. Physicians should weigh the potential of the new technique against the higher radiation dose that is needed. Critical doses that would cause organ damage were not reached.
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Affiliation(s)
- S Diekmann
- Department of Neuroradiology, Charité Centrum 6, Campus Mitte, Charité-University Medicine Berlin, Germany.
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Siebert E, Bohner G, Dewey M, Bauknecht C, Klingebiel R. Dose related, comparative evaluation of a novel bone-subtraction algorithm in 64-row cervico-cranial CT angiography. Eur J Radiol 2010; 73:168-74. [DOI: 10.1016/j.ejrad.2008.07.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2008] [Revised: 07/09/2008] [Accepted: 07/10/2008] [Indexed: 11/29/2022]
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Stricker S, Prüss H, Horvath R, Baruffini E, Lodi T, Siebert E, Endres M, Zschenderlein R, Meisel A. A variable neurodegenerative phenotype with polymerase gamma mutation. J Neurol Neurosurg Psychiatry 2009; 80:1181-2. [PMID: 19762913 DOI: 10.1136/jnnp.2008.166066] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Roche V, Hadjar A, Deloume J, Pagnier T, Revel R, Roux C, Siebert E, Vernoux P. Physicochemical origins of electrochemical promotion of LSM/YSZ. Catal Today 2009. [DOI: 10.1016/j.cattod.2009.03.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Siebert E, Bohner G, Bauknecht HC, Diekmann S, Klingebiel R. Bestimmung zerebraler Zirkulationszeiten mittels 320-Zeilen CT. ROFO-FORTSCHR RONTG 2009. [DOI: 10.1055/s-0029-1221756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Siebert E, Bohner G, Dewey M, Bauknecht C, Klingebiel R. Komparative Evaluation eines neuen Algorithmus zur Knochensubtraktion für die 64-Zeilen CT-Angiographie der supraaortalen Gefäße. ROFO-FORTSCHR RONTG 2008. [DOI: 10.1055/s-2008-1074010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Siebert E, Endres M, Hartmann C, Klingebiel R. [Hypoxic encephalopathy in clinically suspected herpes encephalitis: value of MRI imaging]. ROFO-FORTSCHR RONTG 2007; 179:748-50. [PMID: 17492544 DOI: 10.1055/s-2007-963163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Siebert E, Bauknecht HC, Masuhr F, Bohner G, Klingebiel R. Vergleich von 3D kontrastmittelgestützter und 2D TOF MR-Venographie bei Patienten mit Verdacht auf Sinusvenenthrombose. ROFO-FORTSCHR RONTG 2007. [DOI: 10.1055/s-2007-977368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Siebert E, Kentenich M, Franiel T, Bohner G, Klingebiel R. Die Bedeutung fortgeschrittener Bildgebungstechniken bei der Diagnose des atypischen Glioblastoms. ROFO-FORTSCHR RONTG 2007. [DOI: 10.1055/s-2007-977400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Deseure J, Bultel Y, Dessemond L, Siebert E, Ozil P. Modelling the porous cathode of a SOFC: oxygen reduction mechanism effect. J APPL ELECTROCHEM 2006. [DOI: 10.1007/s10800-006-9208-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Rosini S, Siebert E. Electrochemical sensors for detection of hydrogen in air: model of the non-Nernstian potentiometric response of platinum gas diffusion electrodes. Electrochim Acta 2005. [DOI: 10.1016/j.electacta.2004.11.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Behrens T, Maziak W, Weiland SK, Rzehak P, Siebert E, Keil U. Symptoms of asthma and the home environment. The ISAAC I and III cross-sectional surveys in Münster, Germany. Int Arch Allergy Immunol 2005; 137:53-61. [PMID: 15785082 DOI: 10.1159/000084613] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2004] [Accepted: 12/28/2004] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The indoor home environment has been shown to be associated with the presence of respiratory symptoms and atopic disease. METHODS Two cross-sectional surveys (1995-2000) were conducted, using data from the ISAAC phase I and III surveys, collected in Münster, Germany (n = 6,996, response 81.8%). We analyzed the prevalence ratio (PR) for several indoor exposures and asthma-related outcomes in 6- to 7-year-old children, adjusting for potential confounders. RESULTS Positive associations were observed regarding exposure to molds, environmental tobacco smoke, cooking with gas and space heating with fossil fuels, but most associations were not statistically significant. Surprisingly, presence of a carpet was negatively associated with most respiratory conditions. When restricting the analysis to participants without avoidance of a carpet due to a history of atopic disease, the protective associations disappeared. Mostly, present pet ownership did not show positive associations with respiratory symptoms. However, ownership at different times in life revealed positive associations, particularly in regard to birds owned in the first year of life (PR 1.51, 95% CI 1.11-2.06, for sleep disturbance due to wheeze and PR 1.28, 95% CI 1.01-1.63, for wheeze during the last 12 months, respectively). CONCLUSIONS Only few indoor factors were positively associated with the studied outcomes. The change of associations in participants that reported allergy-related avoidance of carpets suggests that the observed effects are a result of asthmatics' changed behavior. The effect of allergy-related change in behavior and the results observed concerning the ownership of pets at different ages underline the need of establishing a precise temporal relationship between disease and exposure.
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Affiliation(s)
- T Behrens
- Institute of Epidemiology and Social Medicine, University of Münster, Münster, Germany
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Rosini S, Siebert E. Solid-state internal reference electrode based on quinhydrone for hydrogen sensor with acid-doped polybenzimidazole. Electrochim Acta 2004. [DOI: 10.1016/j.electacta.2003.09.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Steiner B, Siebert E, Kempermann G, Kupsch A, Winter C. Enriched environment and physical activity increase cell proliferation and improve motor skills in 6-OHDA modell of Parkinson's disease. Akt Neurol 2004. [DOI: 10.1055/s-2004-833154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Heidrich J, Wellmann J, Hense HW, Siebert E, Liese AD, Löwel H, Keil U. [Classical risk factors for myocardial infarction and total mortality in the community--13-year follow-up of the MONICA Augsburg cohort study]. Z Kardiol 2003; 92:445-54. [PMID: 12819993 DOI: 10.1007/s00392-003-0930-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE The MONICA (MONItoring of trends and determinants in CArdiovascular disease) project in the region of Augsburg, Southern Germany, is the first population-based cohort study in Germany investigating the association of the risk factors hypertension, hypercholesterolemia and smoking with incident myocardial infarction and total mortality, and to assess their impact at the population level. METHODS At baseline, 1074 men and 1013 women aged 45-64 years were randomly selected from the population in the Augsburg region and extensively interviewed and examined regarding their cardiovascular risk profile. They were traced over 13 years from 1984-1997. We calculated incidence rates, hazard rate ratios, population attributable risks (PAR), and rate advancement periods (RAP) according to the three risk factors and their combinations. RESULTS Among men, 107 myocardial infarctions and 204 total mortality events occurred during the study period; in women the number of total mortality cases was 102. The three classical risk factors were associated with incident myocardial infarction in men and with total mortality in men and women over a period of 13 years. Heavily smoking men had a particularly high risk of total mortality (HRR=4.2; 95% CI 2.5-7.0) and myocardial infarction (HRR=3.8; 1.9-7.6). Men with treated hypertension were at equally high risk for both total mortality (HRR=2.4; 1.5-3.7) and myocardial infarction (HRR=2.4; 1.3-4.3). In women, treated hypertension (HRR=2.5; 1.5-4.1) and hypercholesterolemia (HRR=2.0; 1.2-3.3) were most strongly related to total mortality. Regarding the association of risk factor combinations and myocardial infarction among men, the presence of all three risk factors simultaneously (HRR=7.9; 3.6-17.3) and the combination smoking/hypercholesterolemia (HRR=5.8; 3.2-10.5) were particularly hazardous. In total, the three risk factors contributed 54% of the burden of myocardial infarction in the male study population. The rate advancement periods for myocardial infarction related to treated hypertension, hypercholesterolemia and heavy smoking were 10.5, 5.8 and 15.8 years, respectively. CONCLUSIONS Our results confirm the outstanding impact of the classical risk factors on myocardial infarction and total mortality in a southern German population. Coronary heart disease is largely preventable through risk factor reduction. Therefore, risk factor counselling, education and treatment are crucial to prevent people from developing the disease or dying prematurely.
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Affiliation(s)
- J Heidrich
- Institut für Epidemiologie und Sozialmedizin, Universität Münster, Domagkstr. 3, 48129 Münster, Germany.
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Cali C, Foix D, Taillades G, Siebert E, Gonbeau D, Pradel A, Ribes M. Copper (II) selective electrode based on chalcogenide materials: study of the membrane/solution interface with electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. Materials Science and Engineering: C 2002. [DOI: 10.1016/s0928-4931(02)00053-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Kapeller R, Moriarty A, Strauss A, Stubdal H, Theriault K, Siebert E, Chickering T, Morgenstern JP, Tartaglia LA, Lillie J. Tyrosine phosphorylation of tub and its association with Src homology 2 domain-containing proteins implicate tub in intracellular signaling by insulin. J Biol Chem 1999; 274:24980-6. [PMID: 10455176 DOI: 10.1074/jbc.274.35.24980] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A mutation in the tub gene leads to maturity-onset obesity, insulin resistance, and progressive retinal and cochlear degeneration in mice. tub is a member of a growing family of genes that encode proteins of unknown function that are remarkably conserved across species. The absence of obvious transmembrane domain(s) or signal sequence peptide motif(s) suggests that Tub is an intracellular protein. Additional sequence analysis revealed the presence of putative tyrosine phosphorylation motifs and Src homology 2 (SH2)-binding sites. Here we demonstrate that in CHO-IR cells, transfected Tub is phosphorylated on tyrosine in response to insulin and insulin-like growth factor-1 and that in PC12 cells, insulin but not EGF induced tyrosine phosphorylation of endogenous Tub. In vitro, Tub is phosphorylated by purified insulin receptor kinase as well as by Abl and JAK 2 but not by epidermal growth factor receptor and Src kinases. Furthermore, upon tyrosine phosphorylation, Tub associated selectively with the SH2 domains of Abl, Lck, and the C-terminal SH2 domain of phospholipase Cgamma and insulin enhanced the association of Tub with endogenous phospholipase Cgamma in CHO-IR cells. These data suggest that Tub may function as an adaptor protein linking the insulin receptor, and possibly other protein-tyrosine kinases, to SH2-containing proteins.
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Affiliation(s)
- R Kapeller
- Millennium Pharmaceuticals, Inc., Cambridge, Massachusetts 02139, USA.
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Abstract
The electrochemical noise from dry NASICON-based surface electrodes and pregelled Ag-AgCl electrodes is evaluated in saline solutions and on the skin. The electrochemical noise from the electrode/electrolyte interface is found to be negligible (less than 1 microV peak to peak). On the skin, the noise level is highly dependent on the patient. At high frequencies, the skin/electrode interface noise is equal to 'thermal noise' and can be related to the real part of the skin/electrode impedance. At low frequencies (F < 100 Hz), excess noise is observed that varies as f-2. It is tentatively ascribed to a non-stationary process or noise of electrochemical origin due to the ionic nature of the skin. The contribution of residual EMG signal of low amplitude (5 microV peak to peak) is suggested for electrodes with large surface area.
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Affiliation(s)
- C Gondran
- Laboratoire d'lonique et d'Electrochimie du Solide de Grenoble, ENSEEG, BP 75, Saint Martin d'Hères, France
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Siebert E, Hammouche A, Kleitz M. Impedance spectroscopy analysis of La1 − xSritxMnO3-yttria-stabilized zirconia electrode kinetics. Electrochim Acta 1995. [DOI: 10.1016/0013-4686(94)00361-4] [Citation(s) in RCA: 257] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Bartrolí J, Alerm L, Fabry P, Siebert E. Conductive epoxy-graphite composite as a solid internal reference in a NASICON-based sodium ion-selective electrode for flow-injection analysis. Anal Chim Acta 1995. [DOI: 10.1016/0003-2670(94)00655-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
A NASICON-type ceramic (high sodium ion conductor) is proposed to record bioelectric signals. The electrode does not need gel before its application. The principle of the measurements is based on a sodium ion exchange between the skin and the material. Electrical measurements performed in saline solutions show that the electrode is slightly polarisable. The skin-electrode impedance was investigated. The impedance decreases as a function of the time of application. The resistive component is the major source of the impedance change. This can be explained by the perspiration process which occurs immediately with time after the application of the NASICON-based electrode on the skin. The skin condition is also an important parameter. NaCl saline solution or abrasion causes the resistance to decrease markedly.
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Affiliation(s)
- C Gondran
- Laboratorie d'lonique et d'Electrochimie du Solide de Grenoble, Ecole Nationale Supérieure d'Electrochimie et d'Electrométallurgie de Grenoble, Saint Martin d'Hères, France
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Kochevar IE, Moran M, Lyon N, Flotte T, Siebert E, Gange RW. Effects of systemic indomethacin, meclizine, and BW755C on chronic ultraviolet B-induced effects in hairless mouse skin. J Invest Dermatol 1993; 100:186-93. [PMID: 8429241 DOI: 10.1111/1523-1747.ep12462804] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Chronic exposure of hairless mice to ultraviolet B (UVB) radiation is associated with inflammation as well as an altered macromolecular composition of the dermis. This study was designed to determine whether or not various systemic anti-inflammatory agents inhibit chronic UVB-induced changes in the macromolecular content of the dermis and, if so, whether each agent had the same or different effects. The agents and doses were chosen for their ability to inhibit the changes induced by a single exposure to UVB radiation (increased vasopermeability, neutrophil accumulation, and skin-fold thickness). Indomethacin, a cyclooxygenase inhibitor, and meclizine, an H1 histamine receptor antagonist, were administered from slow-release pellets. BW755C, a combined cyclooxygenase and lipoxygenase inhibitor, was administered intraperitoneally 30 min prior to UVB exposure. Animals were exposed to UVB three times per week for 20-26 weeks or were unirradiated. The elastin, glycosaminoglycan and collagen content of the skin were determined by measuring the desmosine, uronic acid, and hydroxyproline levels, respectively. The amount of each macromolecule per area of skin increased after chronic UVB exposure. The increase in desmosine was inhibited by indomethacin; the increase in hydroxyproline was inhibited by meclizine and BW755C. None of the agents inhibited the uronic acid increase. These results suggest that chronic inflammation contributes to the dermal changes seen in chronically UVB-exposed skin and that different inflammatory mediators are involved in the increases observed in elastin, glycosaminoglycans, and collagen.
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Affiliation(s)
- I E Kochevar
- Wellman Laboratories of Photomedicine, Department of Dermatology, Massachusetts General Hospital, Boston 02114
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Hanada K, Gange RW, Siebert E, Hasan T. Protective effects of cadmium chloride against UVB injury in mouse skin and in cultured human cells: a possible role of cadmium-induced metallothionein. Photodermatol Photoimmunol Photomed 1991; 8:111-5. [PMID: 1804290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Metallothionein (MT) is a cysteine-rich protein with antioxidant and metal-chelating activities that is readily inducible by exposure to a variety of stimuli including heavy metals such as cadmium (Cd2+). We have investigated the protective effects of Cd2+ treatment on sunburn cell (SBC) induction in mouse skin in vivo and human cell survival in vitro after UVB exposure. The number of SBC in mouse ear skin was significantly reduced in Cd(2+)-treated mice (10 mumol CdCl2/kg) with each UVB dose (25, 50 and 100 mJ/cm2) compared with controls. Delay of UVB exposure after Cd2+ administration (24 h) and higher doses of CdCl2 (10-30 mumol/kg) were more efficient in reducing SBC formation. Human bladder cancer cells (MGH-U1) made tolerant to Cd2+ by repeated low dose exposure, or cells acutely exposed to high Cd2+ concentration showed increased tolerance (cell survival) to UVB injury. Electrophoretic-autoradiographic analysis of [35S]-cysteine-labeled protein synthesized by cultured cells after Cd2+ treatment revealed increased MT-like protein content. These results suggest that MT is inducible by exposure to Cd2+ in our system and may be a photoprotective agent against UVB-induced oxidative damage in mammalian skin.
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Affiliation(s)
- K Hanada
- Wellman Laboratories of Photomedicine, Department of Dermatology, Harvard Medical School, Boston, Massachusetts
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Miller KH, Butt H, Bamberg E, Fendler K, Hess B, Siebert E, Engelhard M. The reaction cycle of bacteriorhodopsin: an analysis using visible absorption, photocurrent and infrared techniques. Eur Biophys J 1991. [DOI: 10.1007/bf00183532] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
We have optimized Northern analysis at several steps. Overnight electrophoresis was replaced by short gel runs and overnight capillary transfer by rapid vacuum-blotting adapted to Northern analysis. Short uv irradiation was used as a substitute for the usual RNA fixation by baking. Direct staining of RNA before electrophoresis made it possible to check RNA integrity and to evaluate the quality of the size separation immediately after electrophoresis. In this system, RNA transfer onto the membrane support could also be quickly assessed after the blotting step. The net result of all modifications was a doubling of the autoradiography signal compared with that obtained by modern Northern protocols. At the same time, the duration of the procedure was shortened drastically, allowing an autoradiography signal to be obtained within 24 h.
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Affiliation(s)
- R A Kroczek
- Max-Planck-Society Research Unit for Immunology/Rheumatology, Department of Internal Medicine III, University of Erlangen, Federal Republic of Germany
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Swann DA, Garg HG, Hendry CJ, Hermann H, Siebert E, Sotman S, Stafford W. Isolation and partial characterization of dermatan sulfate proteoglycans from human post-burn scar tissues. Coll Relat Res 1988; 8:295-313. [PMID: 3215004 DOI: 10.1016/s0174-173x(88)80002-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Dermatan sulfate (DS) proteoglycans (PGs) were extracted from human post-burn scar (Sc) tissues with 4M guanidinium chloride and isolated from the extracts by DEAE-cellulose chromatography and by differential ethanol precipitation. The DS.PGs were further purified by Sepharose CL-6B column chromatography. The average molecular weight (Mr) of hypertrophic scar (HSc) tissue DS.PGs was 39,000 based on sedimentation equilibrium measurements. Alkaline borohydride treatment of DS.PGs liberated glycosaminoglycan (GAG) chains and the presence of xylitol indicated that these chains were attached to protein core by xylosyl residues. The average Mr of the DS.GAG chain from HSc and normal scar (NSc) samples were 23,500 and 20,000 respectively. After digestion of the HSc and NSc, DS.PGs with chondroitinase ABC in the presence of proteinase inhibitors, two peptide components with Mr values of 21,500 and 17,000 were detected by SDS-polyacrylamide gel electrophoresis using reducing conditions. Analysis of the protein core fractions derived from NSc and HSc DS.PGs by Sepharose CL-6B column chromatography showed the presence of a single NH2-terminal amino acid (aspartic acid) and also that the fractions with different KAV values had an identical NH2-terminal sequence (A1-A5). The A1-A23 sequence of NSc DS.PG (major fraction, C): NH2Asp-Glu-Ala-O-Gly-Ile-Gly-Pro-Glu-Val-Pro-Asp-Asp-Arg-Asp-Phe-G lu-Pro- Ser-Leu-Gly-Pro-Val was the same as reported for a DS.PG isolated from human fetal membrane (HFM) tissue (Brennan et al., 1984). ELISA inhibition assay using monoclonal antibodies raised in rabbit against the NH2-terminal peptide (containing 15 amino acids) of human fetal membrane tissue were found to cross-react with HSc and NSc DS.PGs. Monoclonal antibodies to bovine skin DS.PGs protein core (Pearson et al., 1983) did not show any cross-reactivity with scar DS.PGs. These results show that the scar DS.PGs described here are different from normal bovine skin DS.PGs in the size and type of the protein core, and that in all the samples, the peptide components have the same NH2-terminal amino acid sequence.
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Affiliation(s)
- D A Swann
- Department of Surgery, Shriners Burns Institute, Boston, MA 02114
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Hazod W, Siebert E. Automorphisms on a Lie group contracting modulo a compact subgroup and applications to semistable convolution semigroups. J THEOR PROBAB 1988. [DOI: 10.1007/bf01046936] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Savage K, Siebert E, Swann D. The effect of platelet-derived growth factor on cell division and glycosaminoglycan synthesis by human skin and scar fibroblasts. J Invest Dermatol 1987; 89:93-9. [PMID: 3598205 DOI: 10.1111/1523-1747.ep12580438] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The effect of platelet-derived growth factor (PDGF) on cell division and glycosaminoglycan (GAG) synthesis by fibroblasts isolated from skin and scar was measured. We found that PDGF stimulates cell division more efficiently in normal skin fibroblasts than in scar fibroblasts and decreases GAG synthesis in skin and scar fibroblasts. Using a 4-h pulse label with [3H]thymidine ([3H]Thd) following a 20-h incubation of confluent monolayer cultures with 0-5 units PDGF/ml Dulbecco's modified Eagle's medium, we found a concentration-dependent increase in [3H]Thd incorporation. After incubation of fibroblasts with [3H]glucosamine and 35SO4 in the presence or absence of PDGF, labeled constituents were isolated from the extracellular, pericellular, and cellular fractions by pronase digestion and column chromatography on Sepharose CL4B or DEAE-cellulose and analyzed by cellulose acetate electrophoresis. The presence of PDGF decreased the total amount of 35S incorporated into macromolecules by skin and scar fibroblasts and resulted in an altered distribution of labeled GAGs. Dermal fibroblasts exposed to PDGF for 24 h incorporated a greater percentage of radiolabeled 35S into dermatan sulfate prime (DS') and less into dermatan sulfate (DS) in the extracellular fractions and a greater percentage of 35S into heparan sulfate (HS) in the pericellular fractions than did parallel cultures grown in the absence of PDGF. It is thought than PDGF may have an effect on scar formation by increasing the fibroblast population in the wound tissue and by affecting the total amount and types of matrix components synthesized.
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Siebert E. Infinitely divisible statistical experiments. METRIKA 1986. [DOI: 10.1007/bf01894767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Cytogenetic studies were performed on cell material obtained from surgical specimens of 50 human breast carcinomas and from 61 cancerous effusions of 46 patients. Classical cytogenetic analyses of numerical chromosome changes and marker chromosomes revealed the non-random involvement of chromosomes #X and #22 as monosomics, of chromosomes #3, #7, and #19 as trisomics, and chromosome #1 (particularly p 13 to q 12) in marker formation. Karyotypic evolution was followed in vitro and in vivo and showed a highly individualistic pattern of stability and variability. In addition, a systematic screening for the presence of cytogenetic equivalents of gene amplification (double minutes 'DM', homogeneously staining regions 'HSR') was carried out. A high incidence of DM-positive cases was detected in primary tumors (48%) as well as in metastatic cells from effusions (40%), with the frequency of DM-containing metaphases ranging from 1 to 100% in the positive cases. This finding supports the assumption of the fundamental biological importance of gene amplification in human solid tumors. Furthermore, chromosome breakage and micronuclei were observed in breast carcinoma cells as an apparent consequence of therapy-independent mutability.
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Abstract
Utilizing the phenomenon of premature chromosome condensation (PCC) studies were carried out on interphase chromatin of metastatic cells from 52 cancerous effusions obtained from 45 patients presenting with various solid carcinomas. A highly individual pattern of distribution of the various interphase stages was detected, reflecting the heterogeneity of human solid tumors in an advanced stage. Nevertheless a variety of clinical, biologic, and technical factors were examined for their possible influence on these PCC patterns. The duration in culture was one of the influencing factors, as were the time lapse between the first diagnosis and the sampling of the respective effusion, or the nature of cytostatic therapy. Cytogenetic equivalents of gene amplification, as represented by "double minutes", could be found in the prematurely interphase chromatin of 35 of the 52 effusions. G1-PCC proved to be most reliable with regard to screening of double minutes. In addition, an adequate quality of Giemsa banding was achieved in PCC of 21 out of 24 effusions yielding a sufficient number of well-spread PCC. In six of these 21 cases PCC was superior to metaphase analysis in obtaining karyotypes, while the same was true for 14 of the 52 effusions screened for double minutes. Thus the PCC technique was shown to be an indispensable additional source of cytogenetic information in cells of human solid tumors.
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