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In seiner umfangreichen Textproduktion bringt Slavoj Žižek Denkfiguren der Psychoanalyse Lacans und der Philosophie des deutschen Idealismus mit Werken der zeitgenossischen Popularkultur ins Gesprach. Er „erklart“ die Manifestationen der Popularkultur dabei nicht reduktionistisch, ausgehend von diesen theoretischen Positionen, sondern knupft an das reflexive Potential von Filmen, Romanen und Werbespotts an, um mit ihnen umgekehrt Theoreme Hegels und Lacans zu erlautern bzw. kritisch zu befragen. Einen wichtigen Stellenwert nehmen innerhalb dieses Projektes insbesondere Filme avancierter Regisseure wie Alfred Hitchcock, David Lynch und Krysztof Kieslowsky ein. Žižek bemuht sich um eine Kritik der Popularkultur, in der diese nicht nur als Objekt, sondern auch als Subjekt der Theoriebildung fungiert. Er erlautert sein Verfahren wie folgt: „Lacan mit Hitchcock — und nicht umgekehrt, handelt es sich doch keineswegs um eine psychoanalytische Interpretation Hitchcocks. Vielmehr geht es darum, in bestimmte Lacansche Konzepte etwas Licht hineinzubringen“ (Žižek 2002b: 2). Er begreift die filmischen Ideen der Regisseure nicht als Illustrationen theoretischer Kategorien, sondern als Formen der Reflexion auf sie. Žižek „nutzt“ die filmischen Reflexionen, um von ihnen aus die Theorien Hegels und Lacans — „besser“ als sie sich in sich selbst — verstehen zu konnen. Die Filmsequenzen, die er in seinen Texten kommentiert, dienen also nicht als Beispiele fur oder blose Illustrationen von theoretische(n) Figuren.

Die klassische Rhetorik sucht Antworten auf die Frage, wie mit Sprache Handlungen vollzogen, Überzeugungen vermittelt, Situationen verändert, Stimmungen gewendet und soziale Institutionen geschaffen werden. Andreas Hetzel rekonstruiert das Sprachdenken von Gorgias, Isokrates, Aristoteles, Cicero und Quintilian, um mit und ausgehend von diesen klassischen Autoren eine »Pragmatik jenseits der Handlungstheorie« zu entfalten. In Zurückweisung essentialistischer Implikationen neuzeitlicher Sprachphilosophie wird Sprache dabei als situierte, adressierte und sich erst in ihren (nicht zuletzt politischen) Wirkungen vollendende »Rede« verstanden.

Aims: Natalizumab inhibits adherence of leukocytes to the cerebral endothelium. Leukocytes play a role in regulating the vascular tone. Natalizumab may thus also affect cerebral vasoregulation. This observational study investigates whether neurovascular coupling and cerebral autoregulation are altered after routine clinical infusion of natalizumab in patients with relapsing remitting multiple sclerosis. Methods: In eighteen patients receiving a regular infusion of 300mg natalizumab, neurovascular coupling to visual stimulation (control system approach) and dynamic cerebral autoregulation (phase and gain of 0.1Hz oscillations) were serially measured by transcranial Doppler ultrasound (before, 2 hours and 2 days after the infusion). A repeated examination 28 days after infusion served as a control situation. Results: Neurovascular coupling was altered 2 hours and 2 days after infusion with an overshooting initial hemodynamic response. After 28 days, neurovascular coupling was similar to values before the infusion. Dynamic cerebral autoregulation, cerebral blood flow velocity and pulsatility index in the middle and posterior cerebral artery were unaltered. Neurovascular coupling was not related to age, sex, disease duration, time since last relapse, clinical severity, number of previous natalizumab infusions and occurrence of new headaches after the infusion. Conclusions: Natalizumab infusion is associated with a temporarily increased initial hyperemia to functional activation. Such a hyperreactivity suggests an increased bioavailability of nitric oxide during functional activation. This is perhaps caused by altered leukocyte concentration in the cerebral microcirculation. Hemodynamic effects of immunosuppressive agents acting at the cerebral microcirculation should be considered in future research. Ideally, they could play a role in noninvasively monitoring the direct biological effects of such drugs at their site of action. A placebo-controlled trial is thus warranted to confirm the results of this observational study.

Neurovascular coupling and cerebral autoregulation are two brain intrinsic vasoregulative mechanisms that rapidly adjust local cerebral blood flow. This study examined if stenotic disease affects both mechanisms in the posterior cerebral artery. Ten patients with altogether 13 stenosed (≥50%) posterior cerebral artery (PCA) sides were studied. In addition, 6 control persons without a PCA stenosis were examined. Cerebral blood flow velocity was assessed from both PCAs with transcranial Doppler sonography; blood pressure was measured noninvasively via fingerplethysmography. Neurovascular coupling was assessed by a control system approach using a standard visual stimulation paradigm. Cerebral autoregulation dynamics were measured from spontaneous oscillations of blood pressure and cerebral blood flow velocity by transfer function analysis (phase and gain). The parameters of neurovascular coupling and cerebral autoregulation did not show relevant differences between controls, nonstenosed sides, and stenosed sides. The 3 severely stenosed PCA sides showed a trend to a minor functional flow velocity change and attenuation of the neurovascular coupling mechanism in relation to sides with moderate stenosis. Phase and gain were not altered on sides with PCA stenosis. We conclude that in a group of patients with mainly moderate stenosis of the PCA neurovascular coupling and dynamic autoregulation dynamics seem to be unaltered.

Für die letzten Jahrzehnte lässt sich eine Konzentration negativistischer Selbstbeschreibungen in Wissenschaften, Philosophie und Künsten diagnostizieren. Prominent werden in diesem Zusammenhang Begriffe wie Ambivalenz, Überdeterminiertheit, Unentscheidbarkeit und Unberechenbarkeit. Sie deuten auf einen Prozess des Umbruchs in der Struktur unserer Selbst- und Weltverhältnisse hin, in dem alle Bestimmungen des Wissens und Handelns einem zunehmenden Unbestimmtwerden ausgesetzt sind. Negativität wird dabei am Scheitern anthropologischer Versuche, das Wesen des Menschen zu erfassen, ebenso erfahrbar wie an den antinomischen Strukturen moralischer Prinzipien oder den Schwierigkeiten, die sich für die Naturwissenschaften aus der Unbeherrschbarkeit ihrer Gegenstände ergeben. Das Buch setzt sich zum Ziel, die unterschiedlichen Facetten dieser Negativitätserfahrung zu ergründen.

Objective To compare the diagnostic performance of high-resolution magnetic resonance imaging (MRI) and color-coded duplex sonography (CCDS) in patients with giant cell (temporal) arteritis (GCA). Methods Results of high-resolution MRI and CCDS in 59 patients with suspected GCA were compared with the final clinical diagnosis (based on the American College of Rheumatology GCA criteria and a 6-month followup study). Sensitivity, specificity, and positive and negative predictive values (PPV, NPV) were calculated for each method. In 41 of the patients, imaging results were also compared with the findings of a temporal artery (TA) biopsy. Results Thirty-six of the 59 patients (61%) were ultimately diagnosed as having GCA. Sensitivity of high-resolution MRI and CCDS was 69% and 67%, respectively, specificity was 91% and 91%, PPV was 93% and 92%, and NPV was 66% and 64%, respectively. TA biopsy findings were positive in 24 of the 41 biopsied patients (59%). Sensitivity of high-resolution MRI and CCDS compared with TA biopsy was 83% and 79%, respectively, specificity was 71% and 59%, PPV was 80% and 73%, and NPV was 75% and 67%, respectively. The differences between high-resolution MRI and CCDS were not significant. Conclusion The diagnostic power of high-resolution MRI and CCDS in detecting GCA was comparable. Either of these noninvasive techniques may have value in the evaluation of patients with suspected GCA, and decisions regarding which technique to use may depend on the clinical setting.

Cerebral autoregulation (CAR) is a control machanism of the brain keeping cerebral blood flow constant albeit the arterial blood pressure varies. Impaired CAR may be associated with an increased risk of cerebral ischemic events in patients with obstructive cerebrovascular disease. Spontaneous blood pressure oscillations are analyzed using a nonparametric and two parametric transfer function estimators, i.e. the autoregressive-moving-average model with exogenous inputs or the vector-autoregressive model. Performance of the methods was compared using data from patients with unilateral stenosis or occlusion. We also analyzed reproducibility by comparing partitions of the data an with data from other patients which have been measured twice. Results show that there is no significant difference between methods (ANOVA, p > 0.27), and that CAR measurements can be performed reproducibly (Kendall’s τ, p < 0.0016) by all three methods. In conclusion, CAR measurements by means of spontaneous oscillations can be obtained stably and the presented parametric approaches can serve for future online application of CAR measurement.

Knowledge on autoregulation of cerebellar blood flow in humans is scarce. This study investigated whether cerebellar autoregulation dynamics and CO2 reactivity differ from those of the supratentorial circulation. In 56 healthy young adults, transcranial Doppler (TCD) monitoring of the posterior inferior cerebellar artery (PICA) and, simultaneously, of the contralateral middle cerebral artery (MCA) was performed. Autoregulation dynamics were assessed by the correlation coefficient method (indices Dx and Mx) from spontaneous blood pressure fluctuations and by transfer function analysis (phase and gain) from respiratory-induced 0.1 Hz blood pressure oscillations. CO2 reactivity was measured via inhalation of air mixed with 7% CO2. The autoregulatory indices Dx and Mx did not differ between the cerebellar (PICA) and cerebral (MCA) vasculature. Phase and gain, which describe faster aspects of autoregulation, showed slightly better values in the PICA compared with the MCA (higher phase, P = 0.005; lower gain, P = 0.007). Correlation between absolute autoregulation values in the PICA and the MCA was significant ( P < 0.001). The TCD CO2 reactivity was significantly lower in the PICA ( P < 0.001), which could be influenced by an assumed PICA dilation under hypercapnia. In conclusion, dynamic autoregulation in the human cerebellum is well operating and has slightly faster regulatory properties than the anterior cerebral circulation.

The combination of morphologic and hemodynamic information can help in assessing the risk of embolic stroke associated with thrombi and plaques in the descending aorta. For two acute stroke patients, the determination of individual embolic pathways using flow-sensitive four-dimensional (4D) MRI are reported. 3D visualization of local flow patterns, i.e., retrograde flow channels originating at the site of the atheroma, in conjunction with exact plaque localization, suggested potential embolization of high-risk plaques in the descending aorta although they are located downstream from the supraaortic arteries. Our findings indicate that taking plaques of the descending aorta into consideration may help improve the spectrum of pathologies considered as high-risk sources for brain ischemia. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc.

Objectives: To evaluate a new three dimensional (3D) MRI protocol for the reliable detection of aortic high risk plaques compared with transoesophageal echocardiography (TOE) and to test the reliability of additional MRI in stroke of undetermined aetiology. Methods: 74 acute stroke patients were examined by both TOE and MRI at 3 Tesla with special regard to aortic high risk plaques (ie, ⩾4 mm, superimposed thrombi). ECG synchronised pre- and post-contrast T1 weighted 3D imaging (spatial resolution ∼1 mm3) covering the thoracic aorta was employed. In plaques ⩾3 mm, additional two dimensional T2 imaging and time resolved (CINE) imaging sequences were performed. Aetiology of brain ischaemia was classified according to modified TOAST (Trial of Org 10172 in Acute Stroke Treatment) criteria. Aortic high risk embolic sources detected by MRI in patients with cryptogenic stroke were evaluated. Results: Differences in maximum aortic wall thickness for TOE and MRI were not statistically significant for all aortic segments. The overall number of high risk plaques detected by MRI (n = 74) was substantially higher compared with TOE (n = 47). Most noticeably, MRI identified aortic high risk pathologies in 8/26 (30.8%) patients with cryptogenic stroke after standard diagnostics, including TOE (n = 2: dissection or thrombus; n = 6: plaques ⩾4 mm). Conclusions: Our results demonstrate the feasibility of this 3D MRI protocol for the reliable detection of aortic high risk plaques in acute stroke patients. Because of improved visualisation of the aortic arch and the detection of additional embolic sources not seen by standard diagnostics, this novel technique may become a valuable tool for future patients with cryptogenic stroke.

Background: To investigate whether there is: (1) a specific temporal course of cerebral dysautoregulation in acute ischemic stroke, and (2) a separate detrimental effect of recombinant tissue plasminogen activator (rtPA) on autoregulation dynamics in this situation. Methods: We studied 16 patients with acute middle cerebral artery (MCA) occlusion and rtPA thrombolysis (intra-arterial or intravenous application, or both). Controls were 71 healthy adults and 11 patients with minor stroke not receiving rtPA. Dynamic autoregulation was recorded from spontaneous fluctuations of blood pressure and MCA flow velocity (transcranial Doppler) using two well-described approaches (index Mx, phase shift). Three measurements were performed (study 1: 20 ± 9 h of ictus; study 2: 64 ± 10 h; study 3: 112 ± 7 h). Results: Two groups of clinical outcome were identified: good (modified Rankin scale ≤2, n = 9, MCA infarct volume = 14 ± 16%), poor (modified Rankin scale >2, n = 7, MCA infarct volume = 62 ± 21%). In the good outcome group, no relevant changes in Mx and phase were observed on both MCA sides compared with controls. In the poor outcome group, the index Mx deteriorated over studies 1–3 on affected sides, with worse values compared to the controls (p < 0.05). Phase was already impaired on affected sides of poor outcome patients in study 1 (p < 0.01 vs. controls) and tended to decrease further until study 3. Phase also decreased moderately on contralateral sides in poor outcome patients from studies 1 to 3 (p < 0.05, nonsignificant compared with controls). Conclusions: Cerebral autoregulation is increasingly impaired, mainly on the affected side, over the first 5 days of major ischemic stroke after unsuccessful rtPA thrombolysis. It is bilaterally preserved in minor stroke after successful rtPA thrombolysis, indicating no separate detrimental effect of rtPA on the cerebral autoregulatory mechanism.

Dynamic cerebral autoregulation assessed from blood pressure transients can be considerably impaired in severe internal carotid artery (ICA) obstruction. It is unknown whether impaired autoregulation indicates an increased risk of subsequent ischemic events in this situation. 165 patients with ICA stenosis (> 70 %) or occlusion were prospectively followed until anterior circulation stroke, transient ischemic attack, carotid recanalization without prior event, death or study end. Transcranial Doppler sonography was used to determine autoregulation in both middle cerebral arteries from spontaneous blood pressure fluctuations (correlation coefficient indices Dx and Mx) and respiratory- induced 0.1 Hz oscillations (phase). Standard CO(2) reactivity (CO(2)R) was additionally assessed. All indices were classified as impaired vs. preserved according to reference values from 79 agematched controls. During median follow-up of 24.5 months, there were 16 ischemic events over ipsilateral sides. Competing risk analysis revealed a significant predictive effect on ipsilateral ischemic events for impaired Dx (rate ratio 8.2 [95 % confidence interval 1.7-39], p = 0.0079), phase (5.0 [2-13], p = 0.0007) and CO(2)R (9.4 [2.2-40], p = 0.0025). Restricting analysis to severe stenosis alone (n = 103), only impaired phase (rate ratio 8.6 [1.6-45], p = 0.01) remained as a significant predictor. In a continuous statistical model, only Dx and Mx were significant predictors of ischemic events (p = 0.012 and p = 0.016). In conclusion, impaired dynamic cerebral autoregulation indicates an increased risk of subsequent ischemic events in severe obstructive ICA disease. Its clinical application might thus be of help in identifying higher risk patients.

Das Von-Hippel-Lindau-Syndrom ist eine hereditare Tumorerkrankung. Die interdisziplinare Versorgung der Patienten ist von zentraler Bedeutung, weil die Erkrankung nicht nur die Augen, sondern zahlreiche weitere Zielorgane betrifft. Klassische Veranderungen sind Hamangioblastome von Kleinhirn, Medulla oblongata und Ruckenmark, Nierenkarzinome, Phaochromozytome, Pankreaszysten und Inselzelltumoren sowie Tumoren des Endolymphsacks des Innenohrs. Das Untersuchungsprogramm umfasst die augenarztliche Untersuchung, MRT von Kopf, Ruckenmark und Abdomen. Jahrliche Kontrollen werden empfohlen. Die Durchfuhrung der Untersuchungen, die die Grundlage einer rechtzeitigen und meist erfolgreichen Therapie darstellen, ist eine organisatorische Herausforderung.

To evaluate the accuracy of Doppler sonography compared with angiography, temporary test occlusion of the internal carotid artery (ICA) was performed as paramenter for prediction of tolerance in case of sacrifice of the ICA. The vessel occlusion was done in 67 patients by manual compression over 10 seconds and by twenty minutes lasting balloon insufflation.The results (table 1) show a good correlation between dopplersonographic and angiographic testing in terms of collateral circulation. However, Doppler sonography proved to be more indicative for predicting clinically insufficient collateral supply.

Migraine affects the autonomous nervous system and a recent investigation has also proposed a severe disturbance of dynamic cerebral blood flow regulation in the middle cerebral artery during spontaneous blood pressure oscillations. This study investigates whether dynamic cerebral autoregulation is impaired in persons with migraine among a normal cohort. Out of 94 adults studied to establish normal values for dynamic autoregulation, 19 suffered from migraine according to IHS criteria (10 of them with aura). Transcranial Doppler sonography and fingerplethysmography were used to determine dynamic autoregulation of both middle cerebral arteries following spontaneous low frequency (0.06-0.12 Hz) blood pressure fluctuations (phase and gain of transfer function, correlation coefficient indices Dx and Mx). No significant differences were found for the low frequency variability of blood pressure (power spectral density) and various indices of dynamic cerebral autoregulation between persons with and without migraine. Moreover, no differences were observed between persons with migraine, with and without aura. This study based on a normal cohort does not support the presence of generally impaired cerebral autoregulation dynamics in persons with migraine. Future studies should focus on posterior circulation and particular cerebellar autoregulation.

Die Frage nach den Möglichkeitsbedingungen und motivationalen Ressourcen von Demokratie scheint heute aktueller denn je. Der vorliegende Band stellt sich dieser Frage und erkundet Perspektiven einer umfassenden Demokratisierung von Gesellschaft. Die Autoren beziehen sich dabei - teils zustimmend, teils kritisch - auf die Positionen eines radikaldemokratischen Diskurses (E. Laclau, Ch. Mouffe, J. Derrida, J. Rancière et al.), der sich gegenwärtig darum bemüht, das Politische und die Demokratie jenseits der etablierten Pfade klassischer politischer Theorien neu zu denken. Damit verbunden ist das übergreifende Anliegen der Beiträger, das Politische, das als Kraft einer demokratischen Selbstinstituierung von Gesellschaft verstanden wird, gegen die zunehmende Ökonomisierung aller Lebensbereiche zu verteidigen.

Background and Purpose— A recent study showed a dramatic increase in cerebral hemorrhage comprising atypical locations with low-frequency ultrasound–mediated recombinant tissue plasminogen activator–thrombolysis in humans. Here, we provide a possible explanation for this phenomenon by a side effect observed in a study using the similar ultrasound device. Methods— The study was originally undertaken to investigate by transcranial Doppler sonography, positron emission tomography and perfusion MRI whether transcranial application of wide-field low-frequency ultrasound (300 kHz) improves cerebral hemodynamics in patients with cerebral small vessel disease. Results— Showing no clear positive effect on cerebral hemodynamics in 4 patients and on cerebral perfusion (positron emission tomography) in 2 patients, the study has been terminated early because of a remarkable side effect in the first patient (a 62 year-old man) undergoing perfusion-MRI: detection of frontoparietal extravasation of Gadolinium contrast agent (applied during MRI perfusion imaging preinsonation) on MRI immediately postinsonation. Conclusions— Abnormal permeability of the human blood-brain barrier can be induced by wide-field low-frequency insonation. The observed excessive bleeding rate with low-frequency sonothrombolysis might thus be attributable to primary blood-brain barrier disruption by ultrasound.

Background and Purpose— Transesophageal echocardiography (TEE) is the gold standard in detecting high-risk (ie, aortic thrombi) and potential sources (ie, patent foramen ovale [PFO]) of cerebral embolism. We sought to evaluate the additional information and therapeutic impact provided by TEE in stroke patients and to characterize patients in whom TEE is indispensable. Methods— We included 503 consecutive patients (mean age 62.2 years) with acute brain ischemia. Each patient received TEE and the following routine diagnostics: ultrasound of brain supplying arteries, ECG or Holter-ECG, transthoracic echocardiography, and brain imaging (computed tomography or MRI). Stroke etiology was classified according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. High-risk sources in TEE were: aortic thrombi or plaques ≥4 mm, thrombi in left atrial cavity/left atrial appendage, spontaneous echo contrast, and left atrial flow velocity Results— Stroke etiology was determined by routine diagnostics in 276 of 503 patients (54.9%). Of the remaining 227 patients (undetermined etiology), 212 (93.4%) were candidates for oral anticoagulation (OA). TEE revealed a high-risk source, with indication for OA in 17 of them (8.0%). A potential source leading to OA was found in an additional 48 patients (22.6%). The remaining 147 patients (69.3%) were treated by platelet inhibitors or statins. Conclusions— TEE strongly influenced secondary prevention and led to OA in one third of our patients with stroke of undetermined etiology. TEE is indispensable in all patients being candidates for OA when routine diagnostics cannot clarify stroke etiology.

Nicht dass eine fundamentale Ungewissheit nicht immer schon zum Leben dazu gehört hätte oder eine mehr oder weniger konstante und universelle Bedingung menschlicher Existenz gewesen wäre, erÝ scheint als Problem, sondern - dass mit der Erfahrung einer Zunahme von Unbestimmtheit auch eine mit der Gesellschaft vernetzte TechÝ nik davon betroffen und in den Verunsicherungsprozess einbezogen ist; - dass gesellschaftliche Freiheits- und Optionsgewinne mit nachÝ haltigen Orientierungsverlusten Hand in Hand gehen; - dass die technowissenschaftliche Erzeugung von Wissen neuartige Zonen des Nichtwissens mit hervorbringt; - dass wir nicht wissen können, was wir eigentlich tun sollen und - dass der Umgang mit diesem Faktum die Startbedingung für eine zeitgemäß-unzeitgemäße Philosophie der Technik darstellt. Die Beiträge dieses Bandes (u.a. von Dreyfus, Dupuy, Hörning, Hubig, Nordmann und Willke) gehen nicht nur den unterschiedlichen Aspekten dieser Entwicklung nach. Sie unterÝ nehmen auch den Versuch, die sozio-technischen BestimmungsverÝ suche und Vereindeutigungsstrategien abzuschätzen, die in einer radikal modernen Welt durch die Aufgabe einer »Selbstfestlegung im Unbestimmten« (Luhmann) immer aufs Neue herausgefordert werden.