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  • 1
    Electronic Resource
    Electronic Resource
    Immunohistochemical demonstration of transient increase in prostaglandin F2-alpha after recirculation in global ischemic rat brains (1988)
    Springer
    Acta neuropathologica 76 (1988), S. 496-501 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00686389
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  • 2
    Electronic Resource
    Electronic Resource
    Histological changes in the normal rat brain after gamma irradiation (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 451-459 
    Details
    ISSN: 0942-0940
    Keywords: Radiosurgery ; Gamma Knife ; radiation necrosis ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Radiation-induced changes in the parietal cortex of Wistar rats were observed at various time points after gamma surgery. Maximum dosages of 50, 75, and 120 Gy were given at the iso-center of the radiation using a 4-mm collimator. Conventional histochemical and immunocytochemical analyses, and computer-assisted videomicroscopy were utilized to examine perfusion-fixed brain tissue. Irradiation at a dosage of 50 Gy elicited morphological changes of astrocytes in the parietal cortex at 3 months. Vasodilatation became obvious at 12 months; fibrin deposition was observed in the dilated capillary wall. Neither leakage of Evans Blue from the vasculature into the tissue nor necrosis was observed across the 12 month observation period. Irradiation at a dosage of 75 Gy resulted in morphological changes of astrocytes within 1 month. Dilatation of vessels and capillary thickening were observed at 3 months. Evans Blue leakage and necrosis were observed at 4 months after 75 Gy irradiation. At this time, the walls of arterioles became thickened by subintimal accumulation of fibrin and hyaline substance; this sometimes resulted in occlusion of the lumen. Significant hemispheric swelling was observed at 4 months. Irradiation at a dosage of 120 Gy elicited changes in astrocytic morphology within 3 days. Evans Blue leakage into the tissue was observed by 3 weeks. Vasodilatation became marked at this time point and rarefaction was observed in the irradiated cortex. Necrosis was observed at 4 weeks, however, no significant swelling was observed. Taken together, these findings demonstrate time-dependent and dosage-dependent changes in normal cerebral tissue after Gamma Knife irradiation. These results provide a basis for gauging the impact of gamma surgery in regions of eloquent tissue. An enhanced understanding of the cellular responses to radiosurgery will contribute to developing and evaluating future applications for gamma surgery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01420308
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  • 3
    Electronic Resource
    Electronic Resource
    Enhanced magnetic resonance imaging of the rat brain using a stereotaetic device with a small head coil: Technical note (1995)
    Springer
    Acta neurochirurgica 133 (1995), S. 87-92 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01404955
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  • 4
    Electronic Resource
    Electronic Resource
    Rapid increase of prostaglandin F2-alpha in neurons after subarachnoid hemorrhage in rats: an immunohistochemical study (1989)
    Springer
    Acta neuropathologica 78 (1989), S. 621-628 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00691289
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  • 5
    Electronic Resource
    Electronic Resource
    A stereotactic device for experimental Gamma Knife radiosurgery in rats (1993)
    Springer
    Acta neurochirurgica 125 (1993), S. 156-160 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01401844
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  • 6
    Electronic Resource
    Electronic Resource
    Occlusion of the anterior cerebral artery after gamma knife irradiation in a rat (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 983-991 
    Details
    ISSN: 0942-0940
    Keywords: Gamma Knife ; radiosurgery ; artery ; arteriosclerosis ; vasculitis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The anterior cerebral artery of rats was irradiated at the level of the circle of Willis by Gamma Knife with a maximum dose of 25, 50, or 100 Gy. Occlusion of the anterior cerebral artery was observed in one rat which was followed for 20 months after irradiation of 100 Gy. Cerebral infarction was found at the midline-frontal region and the cingulate gyrus. Arterial wall thickening with fibrosis, splitting of the internal elastic membrane, luminal organized thrombus, and migration of smooth muscle cells into the thrombus were observed. In the anterior cerebral artery, thrombus formation seemed to occur after the endothelial injury and this may play a prominent role for occlusion. In small arteries, various changes were observed in the irradiated tissue. These included fibrosis and thrombus, thickened smooth muscle layer, lymphocytic infiltration, and thickening of vessel wall with fibrosis and fibrinous thrombosis with leakage of fibrin into the surrounding tissue after different doses of radiation and at different observation times. These changes were comparable to the ordinary vascular response to injury including healing vasculitis and arteriosclerosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411289
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  • 7
    Electronic Resource
    Electronic Resource
    Accuracy of an experimental stereotactic system for MRI-based Gamma Knife irradiation in the rat (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 1103-1108 
    Details
    ISSN: 0942-0940
    Keywords: Gamma Knife ; MRI ; Stereotactic atlas ; rat ; stereotactic device
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Stereotactic devices for experimental Gamma Knife irradiation and magnetic resonance imaging (MRI) have recently been developed for experimental studies using rats [6, 7]. The present study examined the accuracy of these devices using the following two approaches. In the first approach, Gamma Knife irradiation was performed using the stereotactic device with targets based on a standard stereotactic atlas. Gadolinium-enhanced T1-weighted magnetic resonance imaging was performed using the MRI stereotactic device. Animals were then sacrificed after Evans blue injection, and the rat brain was sliced using an attachment to the stereotactic device. The center coordinates of the gadolinium-enhanced area from the MRI and Evans blue-stained area from the tissue sections were obtained using a computer-assisted image analysis system. These coordinates were compared with the target coordinates planned from the stereotactic atlas. In the second approach, a thermoluminescence dosimeter was implanted in the rat brain. Stereotactic MRI was performed using the stereotactic MRI device, and the coordinates of the implant were obtained. Gamma Knife irradiation was then performed at this target using the stereotactic device. The absorbed dose was measured and compared with the planning dose. These experiments demonstrated a spatial error of 0.6 mm (standard error ± 0.07) between Gamma Knife irradiation based on a comparison of the atlas coordinates and the lesion, and a spatial error of 1.0 mm (standard error ± 0.13) based on a comparison of the stereotactic MR images and the lesion. Gamma Knife irradiation based on MR images using the stereotactic device demonstrated a maximum error of 10% in absorbed dose at the target center. Together, the stereotactic devices for Gamma Knife irradiation and magnetic resonance imaging provide useful tools for Gamma Knife research in an animal model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01412315
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