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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 109 (1987), S. 3808-3810 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    ISSN: 0942-0940
    Keywords: Cerebral vasospasm ; subarachnoid haemorrhage ; vascular permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The time course of the blood-arterial wall barrier disruption following experimental subarachnoid haemorrhage (SAH) was studied in 24 rabbits. Animals with SAH received two successive blood injections through the cisterna magna. Horseradish peroxidase (HRP) was given intravenously 30 minutes before sacrifice to assess the integrity of the barrier. In the basilar arteries taken from animals that were sacrificed 4 days after the first SAH, HRP-reaction products were diffusely observed in the subendothelial space. Three weeks following the first SAH, permeation of HRP was still observed in half of the animals. However, in animals sacrificed 7 weeks after the first SAH, no permeation of HRP into the subendothelial space was noted. Opening of the interendothelial space seemed to be the major mechanism for HRP permeation into the subendothelial space rather than transendothelial vesicular transport. Disruption of the bloodarterial wall barrier in the major cerebral arteries following SAH may play a role in the pathogenesis of vasospasm.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0942-0940
    Keywords: Subarachnoid haemorrhage ; cerebral vasospasm ; vascular permeability ; FITC-dextran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Disruption of the blood-arterial wall barrier in the major cerebral arteries occurs following subarachnoid haemorrhage (SAH) and may be related to the pathogenesis of cerebral vasospasm. Using FITC dextrans of various sizes, the present study was undertaken to determine if the barrier disruption shortly after SAH occurs equally to various sized tracers. Forty-two Sprague-Dawley rats were divided into 5 groups. Four groups were injected with FITC-dextrans of differing molecular weights (MW): FD4 (MW=4,080), FD40 (MW=40,500), FD 70 (MW=71,400), and FD 150 (MW=156,900). One group was injected with horseradish peroxidase (HRP: MW=40,000). Each group was further divided into two subgroups: with or without SAH. SAH was induced by injecting arterial blood into the cisterna magna. To assess the integrity of the blood-arterial wall barrier by transmission electron microscope, the tracers were intravenously injected prior to sacrificing the animals. The groups without SAH showed no permeability of tracers into the subendothelial spaces of the basilar arteries. In contrast, with the exception of FD 150, FITC-dextrans (FD 4, FD 40, FD 70) were noticed in the subendothelial spaces. The distribution of FITC-dextrans in the elastic lamina was similar to that of HRP. These results suggest that barrier disruption occurs with a wide range of molecular sizes of FITC-dextrans, although there seems to be some limitation to the permeation of the larger molecules. The present study suggests that the mechanism of barrier disruption of the major cerebral arteries in the acute stage following SAH may be vesicular rather than by separation of tight junctions.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 90 (1988), S. 144-151 
    ISSN: 0942-0940
    Keywords: Thromboxane A2 ; Blood-arterial wall permeability ; Major cerebral arteries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Thromboxane, a highly vasoactive substance, is found in the cerebrospinal fluid of patients and experimental animals following subarachnoid haemorrhage. A stable synthetic analogue of thromboxane A2 was administered intracisternally in rabbits. This resulted in an increase in endothelial permeability of the major cerebral arteries to Evans Blue dye and horseradish peroxidase. Thromboxane may be involved in the pathogenesis of cerebral vasospasm and may be related to the contrast enhancement of the arteries in the basal cisterns on CT scans of patients who are prone to develop arterial narrowing.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 4531-4535 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Single-crystal gallium nitride was grown on each of the two polar {0001} planes of 6H-silicon carbide substrates utilizing metal-organic vapor-phase epitaxy. The substrate polarity is clearly shown to strongly influence the surface morphology and the photoluminescence property of the layer. The examination of the layer surfaces using x-ray photoelectron spectroscopy revealed that {0001} GaN grown on the basal planes of SiC changes its polarity in accordance with the substrate polarity.
    Type of Medium: Electronic Resource
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