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  • 1
    ISSN: 0942-0940
    Keywords: Subarachnoid haemorrhage ; cerebral vasospasm ; cerebral artery ; energy metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The contents of glycogen and ATP in the major cerebral arteries were examined in dogs undergoing subarachnoid haemorrhage (SAH). SAH was produced by a single injection of autologous arterial blood (1 ml/kg body weight) into the cisterna magna. Vertebral angiograms showed biphasic basilar arterial narrowings after the injection of blood: Early arterial narrowing occurred immediately after the injection and continued for a few hours. Late arterial narrowing occurred from Day 1 to Day 14 of post-SAH period, and recovered to the normal level on Day 21 of post-SAH period. The content of glycogen in the large pial arteries significantly decreased from Day 1 to Day 14 and returned to the control level on Day 21. The content of ATP in the large pial arteries also decreased from Day 1 to Day 7 and returned to the control level on Day 14. These results show that energy stores in the major cerebral arteries might be diminished during late arterial narrowing.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0942-0940
    Keywords: Subarachnoid haemorrhage ; chronic cerebral vasospasm ; calcium antagonist ; AT877 ; HA 1077
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The initial dose-escalating clinical trial of a novel calcium antagonist, AT877, in patients with aneurysmal subarachnoid haemorrhage is reported. AT877 is characterized by its strong spasmolytic activity, its inhibition of intracellular calcium ion activity, and the inhibiton of several protein kinases. A total of 113 patients (Hunt and Hess grades I to IV) who had undergone surgery within 3 days of aneurysmal rupture entered the study. Patients were divided into 5 groups according to the total daily dose of AT877: I: 20 mg; II: 40 mg; III: 60 mg; IV: 90 mg; and V: 120–180 mg. AT877 was given by intravenous infusion over 30 min two or three times a day for 14 days after surgery. Although AT877 did not completely abolish angiographic vasospasm, severe vasospasm was seen less frequently in patients given higher doses. Vasospasm was the cause of a poor clinical outcome (Glasgow outcome scale rating 3 or greater) in 19%, 7%, 9%, 8%, and 6% of the patients in groups I to V, respectively. The results indicated a favourable clinical effect of AT877 at doses above 40 mg per day. Only mild hypotension was seen, even when 60 mg of AT877 was infused over 30 min. AT877 appears to be effective in patients with subarachnoid haemorrhage. Part of its effect may be attributable to protection of the brain from ischaemic insults due to chronic cerebral vasospasm. However, the drug still needs to be evaluated in a placebo-controlled double-blind trial (which is currently being carried out).
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0533
    Keywords: Neuroblastoma ; Differentiation ; Retinoic acid ; Proto-oncogene ; Tyrosine phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Four human neuroblastoma cell lines exhibited differences in their ability to differentiate into neuron-like cells in response to three different treatments, serum deprivation, or additions of dibutyryl cyclic-AMP or retinoic acid. Expression of N-myc gene product was reduced in neuroblastoma cell line SK-N-DZ differentiated by retinoic acid as compared with untreated cells. On the contrary, expression of c-src gene product, pp60c-src, was considerably enhanced in differentiated SK-N-DZ cells. Tyrosine phosphorylation of several cellular proteins was found to be enhanced in differentiated cells. Alteration in expression of these proto-oncogene products might be important in the differentiation of neuroblastoma cells into neuron-like cells.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0533
    Keywords: Cerebellum ; Granular layer ; Autolysis ; Brain death
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In a study of duration of brain death, granular layer autolysis (GLA) of the cerebellar cortex was analyzed in 45 patients who died of acute cerebrovascular diseases (CVDs). Twelve patients who died of causes other than intracranial disease served as controls. Tonsillar herniation occurred in all who died of acute CVDs. More advanced GLA was seen in the central folia adjacent to the central white medullary body of the cerebellum as compared with the peripheral folia. Widespread GLA involving the most of the peripheral folia was found solely in patients in whom brain death had been present over 18 h. Of the 12 control patients, 4 showed GLA only in the central folia. Although GLA of the central folia might develop during immersion fixation of the brain, the alteration of the peripheral folia is assumed to develop in the period of brain death. Widespread GLA extending to the peripheral folia could be a pathological finding characteristic of brain death, where intracranial blood flow could be absent or significantly reduced. Brain death for little less than 1 day would be necessary for GLA to develop.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between RNA/DNA ratio and egg productivity of adult Paracalanus sp. females was investigated in the frontal area of the Kuroshio current off Kinkazan Island and Boso Peninsula, Pacific coast of Japan in 1989 and 1990, respectively. In the Kuroshio front off Kinkazan Island, the RNA/DNA ratio of females in the surface layer ranged from 3.87 to 6.92 along a transect 8 miles across the front. In the Kuroshio front off Boso Peninsula, the RNA/DNA ratio varied between 5.15 and 7.27 for 32 h in the course of tracking a drifter launched in the front. The RNA/DNA ratio of the females in both frontal areas tended to increase together with ambient chlorophyll-a concentration, and the relationship fitted to Ivlev's formula (P〈0.05). The number of eggs laid in filtered sea-water during 24 h (egg productivity) was also positively correlated with the ambient chlorophyll a concentration (P〈0.05). There was a positive correlation (P〈0.001) between RNA/DNA ratio and egg productivity, and RNA/DNA ratios accounted for about 70% of variation of the egg productivity. Judging from RNA/DNA ratios and female egg productivity in both frontal areas, relatively large physiological or reproductive changes could possibly occur in small temporal and spatial scales in association with change in phytoplankton abundance.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0942-0940
    Keywords: Aneurysms in primates ; experimental conditions ; hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To find out the optimum experimental conditions for the induction of saccular cerebral aneurysms in primates, various procedures for inducing renal hypertension were used in cynomolgous monkeys treated with ligation of unilateral carotid artery and betaamino-propionitrile feeding. Animals were divided into four groups. In the first group, both kidneys were simultaneously compressed with a figure-eight ligation. In the second group, the kidneys were ligated at an interval of one week. In the third and fourth groups, posterior branches of both renal arteries were ligated at the same time, or at an interval of one week, respectively. Hypertension about 200 mmHg was produced only in the last group and aneurysms were noted in more than half of these hypertensive animals. The best procedure for renal hypertension to induce cerebral aneurysms was proved to be ligation of the posterior branches of both renal arteries at an interval of one week. We can conclude that lasting severe hypertension is essential for inducing cerebral aneurysms in monkeys.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0942-0940
    Keywords: Cerebral aneurysm ; endovascular surgery ; EVAL mixture ; liquid embolus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Embolization of three surgically difficult cerebral aneurysms was performed using our newly developed non-adhesive embolic material, EVAL mixture (ethylene vinyl alcohol copolymer). Conventional embolic materials such as detachable balloons or microcoils were not used because of a large or irregular aneurysmal neck. After temporary occlusion of the parent artery with a superselective balloon catheter, the EVAL mixture was slowly injected through a microcatheter placed in the aneurysm or parent artery. The locations of the aneurysms were anterior communicating artery, basilar artery-posterior cerebral artery and basilar artery-anterior inferior cerebellar artery (BA-AICA). One aneurysmal occlusion and 2 parent artery occlusions were performed. Patients had no persistent deficits. The patient with the BA-AICA aneurysm associated with an arteriovenous malformation died of rupture of the residual AVM due to haemodynamic change 2 weeks after embolization. In selected and limited cases, embolization of surgically difficult cerebral aneurysms using EVAL mixture was more effective and safer than embolization using conventional embolic materials such as balloons and microcoils.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 139 (1997), S. 478-479 
    ISSN: 0942-0940
    Keywords: Magnetic resonance imaging ; cerebral infarction ; neoplastic angioendotheliosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0942-0940
    Keywords: Cerebral aneurysm ; internal elastic lamina ; degenerative changes ; catabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to investigate the developmental mechanism of saccular cerebral aneurysms, changes in the internal elastic lamina at the junction of the anterior cerebral artery and the olfactory artery were electronmicroscopically studied in 6 control and 6 experimental rats undergoing ligation of the left carotid artery and branches of both renal arteries. In the control group, spontaneous destructive changes occurred on the luminal side of the internal elastic lamina and progressed from the luminal towards the abluminal side as the elastic lamina advanced to the apex. Close to the apex, these changes invaded and disrupted the whole elastic lamina. The elastic lamina was replaced by sparsely lined up lumps of elastic tissue in the walls of early aneurysmal alterations, and was atrophied and disappeared totally in the walls of aneurysmal alterations that had reached an advanced stage. These spontaneous changes were in agreement with reports in the literature and our own previous investigations. From the findings in the experimental rats it becomes likely that the aneurysmal changes in the elastic lamina are exaggerated forms of the normal catabolic metabolism. Therefore its synthesis on the abluminal side no longer balances with the catabolism on the luminal side. It is strongly suggested that aneurysmal alterations progress from the luminal towards the abluminal side of arterial walls and that the lytic process of elastase might play a role in the degenerative changes in aneurysmal development.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 122 (1993), S. 244-249 
    ISSN: 0942-0940
    Keywords: Cerebral aneurysm ; experimental aneurysm ; rheology ; haemodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A surgical procedure to expose the arterial bifurcation at the base of the rat brain was developed without sacrificing the animal. Using this technique, visualization of flow in and around the induced cerebral aneurysm was achieved by detecting and following fluorescent particles in the blood stream. Cerebral aneurysms were produced by ligating one common carotid artery, inducing experimental hypertension and feeding them with beta-aminopropionitrile. Flow studies of the arterial bifurcation with an early aneurysmal formation showed that there were spiral flows proximal and distal to the bifurcation. This was the first direct visualization of the actual flow in and around cerebral aneurysms in a vital state. This technology can add further information on the development, growth and rupture of cerebral aneurysms.
    Type of Medium: Electronic Resource
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