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  • 1
    Electronic Resource
    Electronic Resource
    The variations of lenticulostriate arteries in the middle cerebral artery aneurysms (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 555-559 
    Details
    ISSN: 0942-0940
    Keywords: Lenticulostriatal artery ; variation ; aneurysm ; middle cerebral artery ; intra-operative study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study attempts to analyse the intra-operative anatomical findings of the lenticulostriate artery (LSA) in 60 patients with middle cerebral artery (MCA) aneurysms who were operated on at the Neurosurgical Department of Atatürk University Medical School, Erzurum, Türkiye. All patients underwent radical surgery for aneurysm by the right or left pterional approach. The findings were recorded during surgical intervention using slides and videotapes of the operations. On average there were 4 (range, 1–14, total number=240) LSAs, in one hemisphere, per case with MCA aneurysm. Twenty percent of LSAs (n=48) arise from the prebifurcation part of the M1 segment, 65% (n=156) arise from the postbifurcation part of the M1 segment, and 15% (n=36) arise from the proximal part of the M2 segment. The great majority of the LSAs (85%, n=204) orginated along the proximal part of the MCA. Of a total of 240 LSAs, 125 (52%) originated from one single large vessel, a stem artery which then divided after 2–10 mm into many branches, 85 (35%) originated as two large proximal trunks, and 30 (13%) originated as multiple small arteries arising along the whole infero-medial wall of the M1 segment of MCA. We concluded that recognition of the anatomical variations of the LSA and detailed knowledge of the microvascular relationships of the MCA aneurysms, will allow neurosurgeons to construct a better and safer microdissection plan, to save time, and to prevent postoperative neurological deficits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411176
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of short-term intravenous insulin administration on the glucagon response to a carbohydrate meal in adult onset and juvenile type diabetes (1977)
    Springer
    Diabetologia 13 (1977), S. 629-636 
    Details
    ISSN: 1432-0428
    Keywords: A-cell ; diabetes ; insulin ; plasma ; glucagon response to glucose and insulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary These experiments were designed to determine whether the abnormal glucagon response of diabetics to a glucose meal can be restored to normal by the short-term administration of exogenous insulin in amounts sufficient to produce normal and above normal plasma insulin levels. The immunoreactive glucagon (IRG) response of nine nondiabetics to oral glucose was compared with that of ten juvenile and ten adult type diabetics. In the absence of exogenous insulin, the IRG response of diabetics was strikingly different from the nondiabetics, rising paradoxically, whereas in nondiabetics there was a decline in IRG. When plasma insulin levels were raised to normal by infusion of insulin (0.06 U/kg for 2 hr), the abnormal IRG response of adult type diabetics was not improved; the IRG response of the juvenile type patients was improved, but remained abnormal. Raising plasma insulin briefly to greater than normal concentrations inproved the IRG response during the glucose meal in both groups, but in the adult group total IRG suppression was still only half that of the nondiabetics; in the juvenile type group it was reduced to the nondiabetic level, but at glucose and insulin levels far above those of nondiabetics. The results are compatible with the view that the glucose-sensing function of the A-cells is, at least in part, mediated by or requires insulin. In juvenile diabetics, the abnormality is corrected by raising plasma insulin to above normal levels; adult onset diabetics appear to be less sensitive even to large doses of insulin during a carbohydrate load.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01236318
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  • 3
    Electronic Resource
    Electronic Resource
    The variations of sylvian veins and cisterns in anterior circulation aneurysms (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 1380-1385 
    Details
    ISSN: 0942-0940
    Keywords: Sylvian vein ; Sylvian cistern ; surgical pitfall ; pterional approach ; aneurysm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The anatomical variations of Sylvian vein and cistern were investigated during the pterional approach in 230 patients with 276 aneurysms of anterior circulation arteries, that were operated on at the Neurosurgical Department of Atatürk University Medical School, Erzurum, Turkiye. All patients underwent radical surgery for aneurysm by the right or left pterional approach. The findings were recorded during surgical intervention and observed through the slides and videotapes of the operations. In our study, we surgically classified the variations of the Sylvian vein, according to its branching and draining patterns. Type I: The fronto-orbital (frontosylvian), fronto-parietal (parietosylvian) and anterior temporal (temporosylvian) veins drain into one sylvian vein. Type II: Two superficial Sylvian veins with separated basal vein draining into the sphenoparietal and Rosenthal's basal vein. Type III: Two superficial Sylvian veins draining into the sphenoparietal and the superior petrosal veins. Type IV: Hypoplastic superficial Sylvian vein and the deep one. Four types of Sylvian vein variations were defined as follows. The Type I was seen in 45% (n = 103), the Type II was found in 29% (n = 67), Type III was recorded in 15% (n = 34) and Type IV, or hypoplastic and deep form was discovered in 11% (n = 26) of patients. The course of the Sylvian vein was on the temporal side (Temporal Coursing) in 70 percent of the cases (n= 160), on the frontal side (Frontal Coursing) in 19% of the patients (n = 45) and in 8 percent of the cases (n= 18) in the deep localization (Deep Coursing). Only 3 percent of the cases (n = 7) showed a mixed course. The variations of the Sylvian cisterns were classified into three types, according to the relationships between the lateral fronto-orbital gyrus and the superior temporal gyrus. In Sylvian Type, the frontal and temporal lobes are loosely (Sylvian Type A, Large) or tightly (Sylvian Type B, Close and Narrow) approximated on the surface thereby covering the area of the Sylvian cistern. In frontal type, the proximal part of the lateral fronto-orbital gyrus herniated into the temporal lobe. In temporal type, the proximal part of the superior temporal gyrus herniated into the lateral fronto-orbital gyrus. The variations of the Sylvian cisterns in 230 patients were as follows: in 31% (n = 71) Sylvian Type A, in 21% (n = 48) Sylvian Type B, in 34% (n = 78) Frontal Type, and in 14% (n = 33) Temporal Type. We concluded that venous perfusion disorder of the brain is the most important factor during the pterional approach. Careful intraoperative assessment and protection of the Sylvian vein, which is a surgical pitfall, is an indispensable part of the operation. The recognition of the anatomical variations of the Sylvian vein and cistern, and the detailed knowledge of the microvascular relationships at that level will allow the neurosurgeon to construct a better and safter microdissection plan, to save time and can prevent postoperative neurological deficits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411115
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of very early cisternal irrigation on basilar artery spasm after SAH in the rat model (1991)
    Springer
    Acta neurochirurgica 113 (1991), S. 69-73 
    Details
    ISSN: 0942-0940
    Keywords: Cerebral vasospasm ; subarachnoid haemorrhage ; cisternal irrigation ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors have investigated the effect of very early irrigation of the cerebrospinal fluid (CSF) space in the haemorrhage rat model of vasospasm. Fifteen rats had basilar cistern irrigation with physiological saline for 3 hours after subarachnoid haemorrhage (SAH), and fifteen control rats had subarachnoid haemorrhage without irrigation of clot. The changes in basilar arteries diameters were determined by angiograms obtained from the rats. The post haemorrhage angiograms showed significant basilar artery spasm in both groups (P⩽0.0005, t-test). However in the last angiogram the basilar artery diameter was found to have the same value measured before subarachnoid haemorrhage in the irrigation group whereas no obvious change was observed in the control group. In the irrigation group the mean diameter of the basilar artery in the last angiogram was 0.412 mm. (0.30 mm to 0.50 mm). None of the animals, treated by cisternal irrigation, showed angiographic vasospasm while the latter group did (P⩽0.0005). Animals treated with physiological saline irrigation had a median clot grade of 0.40 (range grade 0 to 2); control rats had a median grade 2.86 (range grade 1 to 4, P〈0.001, Mann-Withney U test), on the brain stem, indicating significant reduction of clot by lavage. In conclusion, performance of experimental physiological saline irrigation at a very early time after subarachnoid haemorrhage prevents the arteriographic and morphological changes of both acute and late vasospasms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01402117
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  • 5
    Electronic Resource
    Electronic Resource
    Postoperative anosmia after removal of pituitary gland adenomas using the pterional approach (1992)
    Springer
    Acta neurochirurgica 119 (1992), S. 101-103 
    Details
    ISSN: 0942-0940
    Keywords: Pterional approach ; pituitary gland adenomas ; postoperative anosmia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary There have been several studies on anosmia following operations on anterior circulation aneurysms, but no similar study has yet been reported on pituitary gland adenomas which required the transcranial approach. In this study, 38 cases with pituitary gland adenomas, for whom the pterional approach was employed, were observed retrospectively from the point of view of postoperative olfactory nerve function. In the postoperative period only one case complained of impaired sense of smell on the operated side. Eight cases objectively showed olfactory nerve disfunctions. The olfactory nerve function could be preserved at a relatively high rate of 79 per cent. This high rate, we think, resulted from the microtechnique employed as well as the relatively cautious frontal retraction which was less than 1,5 cm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01541791
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  • 6
    Electronic Resource
    Electronic Resource
    Heubner's artery variations in Anterior Communicating Artery Aneurysms (1994)
    Springer
    Acta neurochirurgica 127 (1994), S. 17-20 
    Details
    ISSN: 0942-0940
    Keywords: Recurrent artery of Heubner ; variation ; aneurysm ; anterior communicating artery ; intraoperative study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study attempts to analyse the intra-operative anatomical findings of the recurrent artery of Heubner in 48 patients with Anterior Communicating Artery Aneurysm who were operated on at the Neurosurgical Department of Atatürk University Medical School, Erzurum, Türkiye. All patients underwent radical surgery for aneurysm by the right pterional approach. The findings were recorded during surgical intervention and through the dias and videotapes of the operations. The artery of Heubner originated from the junction of the A 1 and A 2 segments of the anterior cerebral artery (ACA) in 58%, from the A 2 segment of ACA in 23%, and from the A 1 segment of ACA 4%. It was asymmetrically taking off in 13% and hypoplastic in 2% of the cases. Three types of recurrent artery courses were defined. The type I or the superior course was seen in 71 %, the type II or the anterior course was found in 25% and type III or the posterior course was recorded in 4% of patients. We concluded that the recognition of the anatomical variations of the recurrent artery of Heubner and the detailed knowledge of the microvascular relationships of the anterior communicating artery (ACoA) complex, will allow neurosurgeons to construct a better and safer microdissection plan, to save time, and so prevent postoperative neurological deficit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01808540
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  • 7
    Electronic Resource
    Electronic Resource
    Beobachtungen über die Aufstickung hochhitzebeständiger austenitischer Werkstoffe in Luft und Verbrennungsgasen (1980)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 31 (1980), S. 675-682 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Observations concerning nitridation of refractory austenitic materials in air and combustion gasesDamage due to nitridation has frequently encountered on radiation tubes of refractory materials used in industrial furnace construction. Nitridation occurs although the material surface is covered with an oxide layer. Investigations on specimens annealed in air for extended periods have shown that nitridation of materials numbers 1.4848 and 1.4840 starts after an annealing duration dependent on temperature and specimen geometry. At 900° C it begins after approx. 25000 hours, at 1000° C after approx. 1000 hours and at 1100° C after approx. only 100 hours, convex surface zones being preferentially affected. Nitrogen adsorption first results in a transformation from M23C6 to M2(C, N). The latter subsequently grows by chromium extraction from the matrix. The M6C-carbide found in these materials, too, and corresponding to the approximate formula (Cr3Ni2Si)C does not undergo structural changes by nitridation although carbon is partially substituted by nitrogen.Nitridation can probably be attributed to repeated cracking and healing of the oxide layer after a critical oxide layer thickness has been exceeded; this critical thickness is estimated to be approximately 20-30 microns.
    Notes: Schäden durch Aufstickung sind wiederholt an Strahlrohren aus hochhitzebeständigen Werkstoffen, die im Industrieofenbau Anwendung finden, beobachtet worden. Die Aufstickung erfolgt, obgleich die Werkstoffoberfläche mit einer Oxidschicht bedeckt ist.Untersuchungen an langzeitig in Luft geglühten Proben aus den Werkstoffen 1.4848 und 1.4840 zeigen, daß Aufstickung nach einer von Temperatur und Probengeometrie abhängigen Glühzeit einsetzt. Sie beginnt bei 900° C nach etwa 25.000 h, bei 1000° C nach etwa 1000 h und bei 1100° C nach bereits etwa 100 h bevorzugt an konvex geformten Oberflächenbereichen. Durch die Stickstoffaufnahme wird zunächst M23C6 in M2(C, N) umgeformt. Im weiteren Verlauf wächst dann M2(C, N) durch Chromentzug der Matrix. Das in diesen Werkstoffen auch auftretende M6C-Carbid der ungefähren Formel (Cr3Ni2Si)C wird durch die Aufstickung strukturell nicht verändert, jedoch wird ein Teil des C durch N substituiert.Ursache der Aufstickung ist wahrscheinlich ein wiederholtes Aufreißen und Ausheilen der Oxidschicht, sobald eine kritische Oxidschichtdicke überschritten wird. Diese kritische Oxidschichtdicke wird zu etwa 20-30 m̈m abgeschätzt.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19800310902
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