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  • 1
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Hämolytisch-urämisches Syndrom ; Thrombotisch-thrombozytopenische Purpura ; Transkranielle Dopplersonographie ; Vasospasmen ; Key words Haemolytic uremic syndrome ; Thrombotic-thrombopenic purpura ; Vasospasms ; TCD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Cerebral involvement is typical for thrombotic microangiopathies like haemolytic uremic syndrome (HUS) and thrombotic-thrombopenic purpura (Moschcowitz disease or TTP). Symptoms are irritation, restless behaviour, disorientation, disturbance of consciousness, seizures, and focal neurological deficits. The lack of typical imaging changes or pathological observations may explain the unknown pathophysiological cascade leading to the neurological symptoms. We describe the development of HUS/TTP in a 52-year-old woman after acute pneumonia caused by Diplococcus pneumoniae. The patient showed an increasing psycho-organic syndrome with disorientation, followed by severe loss of consciousness and coma. Initially, computed tomography showed slight diffuse brain oedema, which was not found in later follow-up images. Magnetic resonance imaging was normal. The TCD examination revealed general velocity increases and vasospasms (especially MCA, ACA and PCA bilateral and BA). The reduction in blood flow velocities in the basal arteries was accompanied by a marked clinical improvement. The development of vasospasms may be an explanation for the neurological deficits in HUS/TTP. The origin of the vasospasms may be found in disturbed prostacyclin production, increased serotonin or platelet factor IV release, and leucocyte activation with consecutive endothelial damage.
    Notes: Zusammenfassung Mikroangiopathische hämolytische Anämien (thrombotisch-thrombozytopenische Purpura = TTP oder Moschcowitz-Syndrom, hämolytisch-urämisches Syndrom = HUS) gehen oft mit Beteiligungen des zentralen Nervensystemes einher. Typische Symptome sind Gereiztheit, Ruhelosigkeit, Verwirrtheitszustände, Bewußtseinstrübungen, Krampfanfälle oder fokalneurologische Ausfälle. Teilweise fehlende bildmorphologische und pathologisch-histologische Korrelate erschweren die Klärung der Pathogenese. Wir berichten über eine 52 jährige Patienten mit HUS/TTP aufgrund einer Pneumokokkensepsis. Sie entwickelte ein akutes hirnorganisches Psychosyndrom mit progredienter Bewußtseinsstörung bis zum Koma. Die initiale kraniale Computertomographie zeigte eine diskrete, allgemeine Hirnschwellung, welche sich unabhängig von der klinischen Verschlechterung zurückbildete. Die kraniale Kernspintomographie war unauffällig. In der transkraniellen Dopplersonographie fanden sich generalisierte Flußgeschwindigkeitssteigerungen (A. cerebri media, anterior und posterior beidseits sowie A. basilaris). Der ursächliche Zusammenhang zwischen Flußgeschwindigkeitssteigerungen und Bewußtseinsstörungen wird durch die Beobachtung wahrscheinlich gemacht, daß die klinische Besserung analog der Rückbildung der Flußgeschwindigkeitssteigerungen erfolgte. Bei HUS/TTP können Vasospasmen die Ursache neurologischer Ausfälle darstellen. Pathophysiologisch werden ein gestörter Prostacyclinstoffwechsel, eine Erhöhung von Serotonin und Plättchenfaktor IV und eine Leukozytenaktivierung als Ursachen diskutiert.
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  • 2
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Akute Polyradikulitis Guillain-Barré ; Leitungsblock ; Magnetstimulation ; F-Welle ; Motorische Neurographie ; Key words Acute polyradiculitis Guillain-Barré ; Conduction block ; Motor evoked potential ; F-wave ; Motor conduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary A 47-year-old woman developed acute Guillain-Barré-syndrome (GBS) within one day, presenting tetraparesis (muscle strength 1/5 for the upper and 2/5 for the lower extremities) and respiratory failure. On day 5 a cardiac pacemaker was necessary due to severe bradycardia. Electrophysiological studies were performed on days 2, 3, 5, 6, 8, 12, 15, 30 and 40. Our initial findings revealed normal motor conduction velocities and normal spinal motor evoked potentials. However, neither F-waves nor cortical motor evoked potentials could be registered from the upper or lower extremities. The motor conduction of the median nerve remained normal until day 6. The compound motor action potential declined thereafter and disappeared by day 12, indicatign axonal degeneration. No axonal degeneration occurred in the lower extremities. The cervical or lumbar magnetic stimulation excites nerve roots at the level of the foramen intervertebrale. Thus, our findings suggest a conduction block between the foramen intervertebrale and the point where the nerve roots enter the spinal cord.
    Notes: Zusammenfassung Eine 47jährige Patientin entwickelte innerhalb eines Tages eine akute Polyradikulitis Guillain-Barré (GBS) mit einer rein motorischen Tetraparese (Kraftgrad Arme 1/5, Beine 2/5) und Beatmungspflichtigkeit. Am 5. Tag war sie tetraplegisch und wegen Bradykardien schrittmacherpflichtig. Bei dieser Patientin wurden elektrophysiologische Untersuchungen am 2., 3., 5., 6., 8., 12., 15., 30. und 40. Tag durchgeführt. Der initiale Befund zeigte eine unauffällige fraktionierte motorische NLG des N. medianus und eine normale zervikale Magnetstimulation bei ausgefallener Medianus-F-Welle sowie ausgefallener corticaler Magnetstimulation. Die gleiche Konstellation fand sich für den N. tibialis. Die Medianus-NLG blieb bis zum Tag 6 normal, danach reduzierte sich das CMAP bis zum kompletten Ausfall ab dem 12. Tag als Hinweis auf eine sekundäre axonale Degeneration. Dagegen änderte sich die elektrophysiologische Konstellation an der unteren Extremität nicht. Da die Exzitation von Nervenwurzeln durch die Magnetstimulation auf der Höhe des Foramen intervertebrale erfolgt, muß die Läsion bei der initialen Befundkonstellation zwischen Foramen intervertebrale und Eintritt der Nervenwurzel ins Rückenmark liegen.
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1720-1722 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We study the optical nonlinear properties of bulk Cd0.13Zn0.87Te monocrystals at room temperature near the band gap. In time-resolved test and pump experiments, they manifest themselves by a defocalization and an induced absorption of the test beam in the presence of the pump beam. By measuring the spatial intensity profile of the test pulse transmitted through the sample, we determine the real and the imaginary parts of the refractive index as functions of the photon energy and time delay between pump and test pulses.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 1355-1358 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Bulk Cd1−xZnxTe ternary compounds are studied through nonlinear optical pump and probe experiments for different zinc concentrations x. These measurements, similar to excitation spectra, enable us to determine the frequency dependence of the optical nonlinearity. It is attributed to the presence of impurity levels in the material. The two-photon absorption through these states gives rise to a high induced absorption. © 1997 American Institute of Physics.
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  • 5
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We investigate the nonlinear absorption of C60-doped porous sol-gel glasses by single- and double-pulse pump–probe experiments. We find that the reverse saturable absorption (RSA) of these samples can be explained in the frame of a five level system as it is commonly used for C60 solutions. We observe a strong saturation of the RSA at high fluences, especially if the molecules are prepared in the triplet state. In a double-pulse pump–probe experiment we measure the triplet quantum yield for C60 solutions (0.8) and doped glasses (0.25) and the singlet and triplet absorption cross sections. In the first excited singlet state (S1) lifetimes of 1 ns and 65 ps are determined in solutions and glasses, respectively. We find that the dynamics of both depopulation processes, direct S1–S0 relaxation, and intersystem crossing is faster in glasses than in the case where C60 is in solution in a liquid aromatic solvent. We tentatively explain these findings by the absence of a stabilizing solvent and a perturbation of the molecular energy levels due to interaction with the solid glass matrix. We finally determine the lifetime of the triplet states in our glass samples to 2 μs. © 1999 American Institute of Physics.
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  • 6
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present measurements of induced absorption and its dynamics in C60-doped solid xerogel matrices. The measurements are performed in a pump-test geometry using picosecond pulses generated from a frequency doubled mode locked Nd:YAG laser at 532 nm. We observe an induced absorption leading to optical limiting. We find outstanding optical limiting qualities for single shot excitation but some degradation above a certain threshold intensity for repetitive pulses. Below this degradation threshold, the material is stable and its limiting dynamics is studied. A decrease of the initial laser-induced absorption with a time constant of 150 ps is observed, down to a very long-lived constant level. We attribute this dynamics of induced absorption to a transition from excited singlet to triplet electronic states in the C60 molecule. © 1998 American Institute of Physics.
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  • 7
    ISSN: 0022-2313
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
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  • 8
    ISSN: 0022-2313
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
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  • 9
    ISSN: 0022-2313
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
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  • 10
    ISSN: 0044-2313
    Keywords: Copper(I) complex ; homoleptical copper(I) chalcogenolates ; synthesis ; crystal structures ; NMR spectra ; cryoscopic measurements ; electrochemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure of Copper(I)Chalcogenolate-2,2′-Bipyridine Complexes [CuS(2,4,6-iPr3C6H2)]4(Bipy)2 and [CuSe(2,4,6-iPr3C6H2)]2(Bipy)2The oligomeric homoleptical copper(I) chalcogenolate compounds [CuS(2,4,6-iPr3C6H2)]x=4,8 and [CuSe(2,4,6-iPr3C6H2)]6 react with 2,2′-bipyridine (Bipy) to yield the tetranuclear complex [CuS(2,4,6-iPr3C6H2)]4(Bipy)2 (4) and the dinuclear complex [CuSe(2,4,6-iPr3C6H2)]2(Bipy)2 (5). The structures of 4 and 5 were determined by X-ray analysis. In the eight-membered Cu4S4 core of 4 with chair conformation the copper atoms are linked by μ2-bridging selenolate ligands. Only two copper atoms are coordinated by 2,2′bipyridine. The corresponding copper(I) selenolate complex (5) forms a folded four-membered Cu2Se2 ring with μ2-bridging selenolate ligands. The Cu—Cu distance of 2.52 Å is relatively short. In contrast to the reaction performed with 2,2′-bipyridine, addition of phenantroline to 1 respectively 2 yields a dinuclear complex [CuS(2,4,6-iPr3C6H2)]2(Phen)2 (10). NMR spectroskopic and cryoscopic measurement of 4 show that this complex dissociates into smaller fragments in solution which undergo rapid exchange reactions. However, corresponding investigations performed on 5 indicate that the solid state structure is maintained in solution. The electrochemical behaviour of 4, 5 and 10 was studied in CH2Cl2 and in any case no reversible redox processes could be observed.
    Notes: Die oligomeren homoleptischen Kupfer(I)-chalkogenolat-Verbindungen [CuS(2,4,6-iPr3C6H2)]x=4,8 (1, 2) und [CuSe(2,4,6-iPr3C6H2)]6 (3) wurden mit 2,2′-Bipyridin (Bipy) zu dem tetranuklearen Kupferkomplex [CuS(2,4,6-iPr3C6H2)]4(Bipy)2 (4) und dem dinuklearen Komplex [CuSe(2,4,6-iPr3C6H2)]2(Bipy)2 (5) umgesetzt, deren Strukturen durch Einkristall-Röntgenstrukturanalysen bestimmt wurden. In dem achtgliedrigen Cu4S4-Ring von 4 mit Sesselkonformation sind die Kupferatome über μ2-verbrückende Thiolat-Liganden verknüpft, wobei nur 2 Kupferatome von 2,2′-Bipyridin koordiniert werden. Der entsprechende Kupfer(I)-selenolat-Komplex (5) bildet einen gefalteten viergliedrigen Cu2Se2-Ring mit μ2-verbrückenden Selenolat-Liganden. Der Cu—Cu-Abstand ist mit 2.52 Å relativ kurz. Im Gegensatz zu der Umsetzung mit 2,2′-Bipyridin entsteht aus 1 bzw. 2 und Phenantrolin (Phen) ein dinuklearer Komplex [CuS(2,4,6-iPr3C6H2)] 2(Phen)2 (10). Während 5 sich offensichtlich ohne Zerfall löst, wie NMR-spektroskopische und kryoskopische Untersuchungen zeigen, dissoziiert 4 in Lösung in kleinere Aggregate, die miteinander im Gleichgewicht stehen. Das elektrochemische Verhalten von 4, 5 und 10 wurde in CH2Cl2 studiert. In allen Fällen wurden keine reversiblen Redoxprozesse beobachtet.
    Additional Material: 3 Ill.
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