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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 68 (1999), S. 197-201 
    ISSN: 1432-0630
    Keywords: PACS: 36.40; 68.35; 81.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: 2 clusters with about 1000 molecules per unit charge are accelerated to up to 120 keV kinetic energy for mask projective surface bombardment. Patterning is achieved via physical as well as chemical surface erosion. Very smooth eroded surfaces result for bulk natural diamond, silicon, and glass. Polycrystalline, strongly faceted CVD diamond films are effectively planarized. Submicron structures with various wall inclinations can be generated. Atomic force microscopy of individual impact structures reveals nanometer-sized hillocks instead of craters. The collective motion of the impacted surface material is considered crucial for the cluster impact-induced nanomodifications. Atomic ion beam lithography is considered for comparison.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0942-0940
    Keywords: Traumatic aneurysm ; iatrogenic aneurysm ; cavernous carotid artery ; balloon occlusion ; extra-intracranial bypass ; yttrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We present 7 cases of false intracavernous carotid artery aneurysms. Four occurred after trauma and three were caused iatrogenically. Two of the latter occurred in patients with pituitary adenomas, one after transsphenoidal microsurgery and the other after yttrium [YI90] seed implantation into the sella. The third iatrogenic aneurysm was seen shortly after transcavernous tumour surgery. In five of our seven patients massive, delayed, lifethreatening epistaxis was the leading symptom. All traumatic cases were associated with immediate unilateral blindness or blurred vision and with skull base fractures. One of these had a concomitant carotid cavernous fistula. Treatment of choice of our 5 recent cases was permanent balloon occlusion of the intracavernous carotid artery at the level of the lesion. Collateral circulation was evaluated prior to definitive carotid occlusion using a balloon test occlusion. During the balloon test adequate collateral circulation was defined as symmetric angiographic filling of both hemispheres. Awake patients were neurologically examined continuously. In unconscious patients transcranial Doppler sonography, electroencephalographic and somatosensory evoked potential monitoring was used in addition. Intra-operative heparin administration was not reversed with protamin. A postoperative continuous heparin infusion was not found necessary. In our two early cases this technique was not available: In the first case we accomplished aneurysm occlusion by a surgically introduced Fogarty balloon catheter. Our second patient needed surgical trapping of the involved carotid after early unsuccessful attempts of selective aneurysm occlusion, After treatment no further epistaxis occurred. Follow-up angiography showed persistent aneurysm occlusion. The results were excellent in 5 cases and good in 1 case. One patient with bilateral lesions suffered a stroke after occlusion of the second, remaining carotid artery, despite functioning bilateral extra-intracranial bypasses. Four years later there is a mild dysphasia still present in this patient. The mean follow-up time was 75.6 months.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0942-0940
    Keywords: Keywords: Meningioma; vascular endothelial growth factor; pial supply; angiogenesis; brain oedema
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The correlation between angiographic neovascularization, peritumoural brain oedema (PTBOe) and the expression of vascular endothelial growth factor (VEGF) , was analysed in 30 patients with intracranial meningiomas. Pre-operative angiograms were examined for the existence of either an exclusively dural tumour blush or an additionally pial tumour supply from cerebral arteries. Furthermore the presence of macroscopic tumour-neovascularization and dysplastic changes of tumour-draining cerebral veins was evaluated. VEGF expression was investigated on histological tissue samples, using immunohistochemical techniques. VEGF immunohistochemistry and neuroradiological evaluations were performed in double blind fashion. Tumour volume and the amount of oedema were calculated by computerized tomography (CT) or magnetic resonance imaging (MRI). The oedema-tumour volume ratio was defined as oedema index (OeI). Compared to VEGF-negative meningiomas, tumours with striking VEGF staining revealed a significant higher mean oedema index (OeI=4,2 vs. OeI=1,5; p〈0.018), and a higher oedema incidence (91,7% vs. 44,4%; p〈0.046). Equally, meningiomas with additionally tumour supply from cerebral arteries were associated with a significant higher mean OeI (OeI=4.1 vs. OeI=1.2; p〈0.01) and oedema incidence (94,7% vs. 20,0%; p〈0,0023) than meningiomas with exclusively tumour supply from dural arteries. All meningiomas with striking VEGF-expression were associated with vascular tumour supply from cerebral arteries, but VEGF-negative tumours only in 50% (p〈0.029). These data suggest a link between VEGF-expression, arterial tumour supply and peritumoural brain oedema. The development of tumour supply from cerebral arteries may be important for formation of meningioma-related oedema. Therefore, VEGF may represent a potent mediator in the evolution of this type of vascularization in meningiomas.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0942-0940
    Keywords: Aneurysms ; basilar artery ; detachable coils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Thirteen patients with basilar artery bifurcation aneurysms, treated by electrothrombosis using electrically detachable coils, are presented. Nine of them presented after hemorrhage, two with mass effect, and two were found coincidentally with other ruptured aneurysms. Selection for endovascular therapy was based on the following criteria: 1) poor clinical condition (Hunt and Hess III-V); 2) high surgical risk; 3) age and poor medical condition; 4) morphological features (small necked aneurysms). With endovascular Guglielmi detachable coils aneurysm occlusion ranging from 70–100% was achieved in all cases. All five small necked and two large broad necked aneurysms were totally occluded. Two large aneurysms had a 95% occlusion and two other large aneurysms were 90% occluded. In another patient with a large broad based aneurysm only an 80% occlusion was achieved, because of tortuosity of the vertebrobasilar system. Our last patient, who presented as grade V clinically, was partially treated with a 70% aneurysmal occlusion. The clinical results were excellent in 10 and good in 2. The only poor outcome was seen in the grade V patient. There was no morbidity or mortality related to therapy. The only complication was an asymptomatic dissecting aneurysm at the origin of the vertebral artery. Angiographic follow up time ranged from 6 to 20 months with a mean of 9 months. Four patients were treated too recently to have their angiographic follow up at 6 months. Two patients were lost to follow up. Clinical follow up ranged from 1 to 17 months with a mean of 8.9 months. The analysis of our cases clearly shows that aneurysms, which were densely packed with coils, especially if small necked, were less likely to be reperfused and showed a longlasting stable result. Large broad based aneurysms were more likely to be reopened by blood flow after the first procedure, especially if loosely filled with coils, and needed up to 3 interventions to achieve a satisfying result, whereas later in the series a high percentage rate of occlusion was seen after the first procedure. We consider now also a less than 100% occlusion acceptable, because most of the aneurysms will rupture at the dome, which was occluded in all our cases. We conclude, that this new endovascular method is a viable alternative in the treatment of posterior circulation aneurysms with a high surgical risk, in old patients and those in poor clinical and medical condition.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0942-0940
    Keywords: Dural arteriovenous fistulas ; intracranial haemorrhage ; endovascular therapy ; operative approach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 30 cases of cranial dural arteriovenous fistulas, treated between 1983 and 1992, are reported. Twelve presented with an aggressive clinical couse including intracranial haemorrhage, progredient neurological deficit, medically intractable seizures, and cerebellar symptoms. The other 18 patients had a more benign clinical presentation with audible bruit, exophthalmus, chemosis, and cranial nerve dysfunction. One of the latter had symptoms of pseudotumour cerebri due to sinus occlusion with contralateral sinus stenosis. The most common location was at the transverse sinus, followed by the cavernous sinus, the tentorial ring, and the orbita. Four vessel angiography verified the diagnosis and demonstrated all fistulas, mainly supplied by branches of the external carotid artery. 16 of 18 benign lesions were treated by endovascular therapy alone. Two recent patients received adjuvant stereotactic radiosurgery. Among these 18 patients 2 remained untreated, one because of spontaneous fistula thrombosis prior to therapy and one because of poor medical condition. 12 of 16 treated benign dural fistulas were partially occluded. in 6 of them spontaneous fistula thrombosis occurred during the following months. Total endovascular obliteration was achieved in the remaining 4 patients. 7 of 12 aggressive fistulas were embolized only, one of them having additional radiosurgery. Two of them were totally obliterated and five partially. Surgery was performed in the remaining 5 aggressive fistulas. Complete microsurgical excision was achieved in 2 and partial in further two, who presented initially with a lifethreatening intracerebral clot. In one early case ligation of the external carotid artery was done, which is now obsolete. Over all 20 of 28 treated patients became asymptomatic or improved clinically. 3 of the remaining 8 patients were unchanged, two deteriorated despite therapy, and 3 worsened after therapy. All of the latter complications occurred early in our series due to thomboembolic events during the procedure. One surgical patient suffered from a new facial nerve palsy postoperatively. Follow up time in all treated patients was between 1 and 139 months with a mean of 48,3 months.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 134 (1995), S. 177-183 
    ISSN: 0942-0940
    Keywords: Brain aneurysms ; endovascular treatment ; GDC-embolization ; follow-up
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary GDC (Guglielmi detachable coil)-embolization for the treatment of brain aneurysms was first published by Guglielmi in 1991 [1,2] and has become an integral part of the treatment strategy for cerebral aneurysms in many places around the world. Low morbidity and mortality rates [3] are set against the limited possibilities of aneurysm neck occlusion, especially in large necked aneurysms. Depending on the architecture and on the kind of coil distribution, recanalization of the neck is more or less frequent. Nevertheless, rebleeding rates are low [4]. In our series of 211 brain aneurysms from March 1992 to June 1994, 74 (35%) patients underwent GDC-embolization. 4 patients received combined treatment (GDC-embolization and subsequent surgery). Follow-up angiography was performed on 41 patients (55%) at periods of 6, 12, and 24 months (mean follow-up 8 months). To demonstrate the results in a graphic display, the aneurysms were grouped according to location and size. The analysis of the follow-up results shows the highest occlusion stability in aneurysms of the basilar tip, followed by aneurysms of the PICA origin, the basilar trunk and the PCA. Less stability was obtained in aneurysms of the PCom followed by MCA, Acom and aneurysms of the internal carotid (Cl, ophthalmic). Aneurysms of the posterior circulation show generally better results than those located in the anterior circulation. This makes (in combination with the increased surgical difficulties of aneurysms in the posterior fossa) the GDC-treatment especially useful for posterior circulation aneurysms.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Gene 95 (1990), S. 303-304 
    ISSN: 0378-1119
    Keywords: Recombinant DNA ; gene family ; nucleotide sequence ; overlapping clones ; promoter architecture ; pseudogene
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Gene Structure and Expression 1088 (1991), S. 151-154 
    ISSN: 0167-4781
    Keywords: (Mus musculus) ; Gene family ; Histone gene ; Minor small nuclear ribonucleoprotein ; RNA 3' processing
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0375-9474
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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