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  • 1
    ISSN: 1432-0533
    Keywords: prostaglandin F2α ; Immunohistochemistry ; Ischemia ; Recirculation ; Carbodiimide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Immunohistochemical localization of prostaglandin F2α (PG F2α) was studied in 24 rats. In 21 rats, global brain ischemia was produced for 5 min by Pulsinelli's method. Prior to decapitation, 13 were recirculated for 5 min, while the remaining eight were not. Three recirculated rats were pretreated with indomethacin before the occlusion. Hypotension was induced during the occlusion to 40–50 mm Hg of mean arterial blood pressure in 11 rats including those unrecirculated, recirculated and pretreated with indomethacin. Three normal rats without occlusion of arteries served as control. The brains were snap frozen and 10-μm cryostat sections were incubated in rabbit anti-PG F2α serum and stained by the indirect immunofluorescence method after fixation in carbodiimide and in Zamboni's solution. Positive staining for PG F2α was noted mainly in pial vessels in normal and ischemic rats both with and without hypotension. The rats recirculated without hypotensive ischemia revealed a positive reaction in the walls of pial and parenchymal vessels. All rats recirculated after the hypotensive occlusion showed positive staining in blood vessels, in the cytoplasm of neurons (especially in hippocampi) and in the interfascicular oligodendrocytes. The above results indicate that recirculation after ischemia results in an increase in PG F2α in parenchymal vessels, neurons and oligodendrocytes.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Subarachnoid hemorrhage ; Prostaglandin F2-alpha ; Hippocampus ; Purkinje cell ; Intracranial hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of subarachnoid hemorrhage (SAH) with various degrees of increase in intracranial pressure (ICP) on the staining of prostaglandin F2-alpha (PG F2α) were studied in rat brains. SAH was produced in 18 rats by injection of 0.18–0.20 ml of autologous arterial blood/100 g body weight into the cisterna magna. By changing the speed of injection, the ICP was transiently increased by 346±68 (mean±S.D.) mm Hg in eight rats (including three pretreated with indomethacin), by 200±42 mm Hg in five rats, and by 6±4 mm Hg in the other five. Three rats injected with the same volume of mock cerebrospinal fluid (CSF) with ICP increased by 217±67 mm Hg and five normal rats without injection served as controls. All animals were decapitated 15 min after injection. The cryosections were stained for PG F2α using an indirect immunofluorescence method. Positive staining for PG F2α was noted only in pial vessels in all normal and mock-CSF-injected rats. In SAH rats with ICP increased by 6±4 mm Hg, there was a positive reaction in hippocampal neurons and Purkinje cells as well as blood vessels. SAH rats with higher ICP showed stronger PG F2α staining in the above areas, as well as in cerebellar granule cells. All rats pretreated with indomethacin showed a smaller increase in staining. The above results indicate that subarachnoid blood clots per se produce a rapid increase of PG F2α in neurons and blood vessels of both cerebrum and cerebellum, and that this increase is augmented by intracranial hypertension.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0533
    Keywords: Prostaglandin F2-alpha ; Immunohistochemistry ; Transient increase ; Hippocampus ; Purkinje cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The changes in prostaglandin F2-alpha (PG F2α) staining over 3 days of recirculation in both fore-and hindbrains were studied. Five minutes of global ischemia was produced in 24 rats by Pulsinelli's method with hypotension around 50 mm Hg of mean arterial blood pressure. Eight rats (including three pretreated with indomethacin) were recirculated for 5 min, three for 1 h, five for 2 h and five for 3 days. Five normal rats without occlusion of vessels served as controls. The brains were snap frozen. Ten-micrometer cryosections were stained for PG F2α by the indirect immunofluorescence method after fixation in carbodiimide and in Zamboni's solution. Positive staining for PG F2α was noted in pial vessels in all normal and ischemic rats. Recirculated rats revealed the strongest reaction at 5 min after recirculation in blood vessels and in neuronal cytoplasm (especially in hippocampi and in Purkinje cells). The intensity of staining was markedly reduced after 1 h. Rats pretreated with indomethacin showed less increase in staining. The above results indicate that recirculation after ischemia produces a transient increase in PG F2α in blood vessels and neurons of both fore- and hindbrains.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0942-0940
    Keywords: Reperfusion ; cerebral ischemia ; Sprague-Dawley rat ; middle cerebral artery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A reproducible model of reversible, focal ischemia was developed for use with the normotensive, Sprague-Dawley rat. Blood flow to the left cerebral hemisphere was interrupted by occluding simultaneously the left middle cerebral artery and both carotid arteries (CCA). The arterial occlusion lasted for 1, 2 or 3 hours after which animals survived for 3 days. The volume of brain infarction was determined utilizing computer-assisted measurements of serial brain sections stained with triphenyltetrazolium. Tissue infarctions of variable size were observed following arterial occlusions which persisted 1 or 2 hours. In contrast, remarkably-consistent infarction size was obtained following a three hours period of occlusion. Tissue edema was also estimated by measuring the volumes of the two hemispheres and expressing these values as a ratio for each animal. The volume ratio was significantly greater in the 3 hour ischemic group, indicating the occurrence of edema in the infarcted hemisphere. These results demonstrate that reversible vascular occlusion in the normal, Sprague-Dawley rat results in consistent amounts of tissue infarction. This approach represents an attractive model system for studying the pathophysiological effects of transient, focal ischemia and for testing the effects of putative, therapeutic strategies.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0942-0940
    Keywords: MRI ; rat, brain ; stereotactic atlas ; Gamma Knife
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A stereotactic device (SDM) was developed for performing consistent magnetic resonance imaging (MRI) of the rat brain. The SDM was developed by adapting a radiofrequency transmit/receive head coil of 4.4 cm inner diameter (quadrature birdcage head coil), and utilizing partial acrylic construction for the positioning elements. The small head coil provides improved resolution and accuracy of the image, while the stereotactic holder permits repeatable and accurate imaging of identified brain structures. This system provides several advantages over existing experimental MRI devices. The SDM ensures that the head is always placed in the center of the coil in a uniform fashion. Standardized positioning of the skull optimizes image quality and provides a consistent orientation of the brain. In addition, a widely-utilized coordinate system described by Paxinos and Watson can be employed to assist in the identification of structures and to facilitate surgical planning. The SDM is compatible with a recently-developed stereotactic device for radiosurgery with the Gamma Knife, thus permitting the planning and performance of experimental radiosurgery using the same coordinate system. The SDM also provides the ability to perform MRI and radiosurgery at different times, thus avoiding the need for prolonged anesthesia during an experimental study. Finally, the SDM allows repeated MRI of the same, identifiable positions in the brain during longitudinal experimental studies. The utility of this device is demonstrated here by examining the time course of cerebral damage that evolved within a radiosurgical focus after gamma irradiation.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 14 (1966), S. 96-104 
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei 3 Fällen konnten die Hirngefäße nicht angiographisch mit Kontrastmittel gefüllt werden. Bei allen 3 Fällen wurde gleichzeitig der intrakranielle Druck im supratentoriellen Raum über einen Katheter gemessen. Er lag gleich hoch wie der Blutdruck. Bei einem Patienten wurde ein rechtsseitiges Brachialisangiogramm ausgeführt. Dabei fand sich außerdem ein Zirkulationsstillstand der A. vertebralis in Höhe des Hinterhauptsloches. Die Autoren vertreten die Ansicht, daß die Ursache der Nichtfüllung der intrakraniellen Gefäße bei erheblicher intrakranieller Drucksteigerung auf einer mechanischen Kompression der Gefäße beruht, und zwar im Bereiche des Sinus sagittalis oder an der Einmündung der zerebralen Venen in die Sinus.
    Abstract: Résumé Le non-remplissage de la circulation cérébrale par le produit de contraste lors de l'angiographie a été démontré chez 3 malades. Dans ces trois cas, la pression intra-crânienne était mesurée par un cathéter placé dans l'espace supra-tentoriel; il fut démontré que celle-ci était la même que la pression artérielle. Un artériogramme brachial droit pratiqué sur un malade, montre un arrêt de la circulation de l'artère vertébrale au niveau du « foramen magnum ». Nous pensons que le non-remplissage observé lors d'une hypertension intra-crânienne-sévère est le résultat d'une compression mécanique des vaisseaux cérébraux et qui, spécifiquement, se remarque au niveau du sinus sagittal ou à la jonction des veines cérébrales et des sinus.
    Notes: Summary Non-filling of the cerebral circulation with contrast material at the time of angiography has been demonstrated in three patients. In all three cases intracranial pressure was measured from a catheter in the supratentorial space and determined to be equal to the blood pressure. A right brachial arteriogram was performed in one patient, and arrest of flow in the vertebral artery at the level of the foramen magnum was also found. We believe that the non-filling phenomenon which occurs in the presence of severe intracranial hypertension is due to mechanical compression of the cerebral vessels, and specifically, that this occurs at the level of the sagittal sinus or at the junction of the cerebral veins with the sinuses.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 125 (1993), S. 156-160 
    ISSN: 0942-0940
    Keywords: Gamma Knife ; radiosurgery ; rat ; stereotaxis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A rat stereotactic device was designed for use in Gamma Knife radiosurgery. Experimental radiosurgical lesions were made in superficial and deep cerebral structures to verify the accuracy of the coordinate system, which is based on a standard rat stereotactic atlas. Calculated dosages were shown to be accurate utilizing thermoluminescence dosimetry. Two additional features of the device permit the surgical positioning and placement of electrodes, and postmortem slicing of the brain according to the same coordinate system. This new apparatus allows precise and repeatable gamma irradiation of the rat brain without the need for expensive and time-consuming imaging techniques. Studies of this type will provide a rapid means for examining the effects of radiosurgery on the central nervous system.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The pharmacological action of a leukotriene antagonist FPL 55712 was studied on canine cerebral arterial segments. FPL 55712 at concentrations of 10−6M and 10−5M showed dosedependent inhibition of the constrictor responses of the artery to prostaglandin F2α. The constrictor responses of the artery to either serotonin or haemoglobin were suppressed by 10−5M FPL 55712, while 10−6M FPL 55712 failed to alter the responses. The KCL-induced constriction was not affected by treatment with either 10−6M or 10−5M FPL 55712. The present results suggest that FPL 55712 has vasodilator properties other than those related to the inhibition of leukotrienes.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0942-0940
    Keywords: Endothelium-dependent relaxation ; hypoxia ; subarachnoid haemorrhage ; vasospasm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An important role of endothelium-dependent relaxation in the local regulation of vascular tone has been suggested. In the present study, the effect of hypoxia on endothelium-dependent relaxation was investigated in canine and rabbit basilar and in rabbit common carotid arteriesin vitro, using an isometric tension recording method. Hypoxia was introduced by changing the gas mixture in thein vitro chamber from 95% O2-5% CO2 to 95% N2-5% CO2. Thrombin and acetylcholine were used to induce endothelium-dependent relaxation. Thrombin at 0.1 and 1.0U/ml, respectively, caused dose-dependent relaxation of the canine basilar artery precontracted by 10−6M prostaglandin F2α. Acetylcholine also evoked dose-dependent relaxation of rabbit basilar and common carotid arteries precontracted by serotonin. Under hypoxic conditions, the relaxing effect of thrombin or acetylcholine decreased both in canine and in rabbit arteries, although it was not significant in rabbit basilar arteries. It has been postulated that following subarachnoid haemorrhage, diffusion of oxygen to the walls of the major cerebral arteries might be impaired by the subarachnoid clot. This could cause hypoxia of the arteries and contribute to vasospasm by suppressing endothelium-dependent relaxation, as well as by enhancing the contractile responses of the cerebral arteries to the vasoconstrictor agents in the bloody cerebrospinal fluid.
    Type of Medium: Electronic Resource
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