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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Acta neurochirurgica 82 (1986), S. 50-56 
    ISSN: 0942-0940
    Schlagwort(e): Pulse pressure ; intracranial pressure pulse wave ; elastance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The pulse pressure (PP) of the intracranial pressure pulse wave (ICPPW) was measured in experimental and clinical hydrocephalus: namely, obstructive and kaolin-induced hydrocephalus as an experimental study, and noncommunicating and communicating hydrocephalus as a clinical study. At approximately the same ICP level, the PP was much higher in the obstructive hydrocephalus group and slightly higher in the kaolin-induced hydrocephalus group than in the controls. Also the PP level in noncommunicating hydrocephalus patients [3.19mm Hg (SD: 1.04)] was significantly (P〈0.05) higher than that in the communicating hydrocephalus patients [1.88 mm Hg (SD: 0.60)]. The results of our research suggest that the stronger the disturbance of the communication of the CSF between cranial cavity and spinal cavity the higher the PP of ICPPW. This results from the distensibility of the spinal dural sac and exerts a great influence on the elasticity and the PP of the cranial system. It is reasonable, therefore, to suggest that a marked increase in the ratio of the PP to the ICP in the normal or slightly high ICP hydrocephalus may indicate disturbance of the CSF flow, especially loss of CSF communication between the cranial and spinal compartments.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 43 (1987), S. 1786-1788 
    ISSN: 1600-5759
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Acta neurochirurgica 112 (1991), S. 28-36 
    ISSN: 0942-0940
    Schlagwort(e): Cerebral aneurysm ; cisternal drainage ; vasospasm ; hydrocephalus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effect of continuous cisternal drainage on cerebral vasospasm was studied under strict criteria in 140 patients with ruptured intracranial aneurysms. The degree of subarachnoid haemorrhage (SAH) on the computed tomography scan was graded from I to IV. The patients were classified according to the total amount of cisternal drainage into three groups, regardless of the duration of the drainage and whether or not it was accompanied by irrigation; i.e., those with less than 500 mL (group 1∶57 cases), those with 500–3000 mL (group 2∶ 44 cases), and those with 3000–9500 mL (group 3∶ 39 cases). While correlations could be found between both clinical and SAH grades with the severity of vasospasm, closer correlation could be found in the SAH grades. In analyzing the cases with subarachnoid haemorrhage grades III–IV (severe clots), the angiographic vasospasm was less severe in groups 2 and 3 than in group 1, and the incidences of permanent symptomatic vasospasm and low-density area on computed tomography were lower in groups 2 and 3 than in group 1. Regarding the surgical outcome in cases with SAH grades III–IV, the mortality rate was lower in groups 2 and 3 (22% and 19%) than in group 1 (33%). Further, the rate of good recovery was higher in groups 2 and 3 (61% and 57%) than in group 1 (28%). However, there were no differences between groups 2 and 3 in cerebral vasospasm or in surgical outcome. As a shortcoming of continuous cisternal drainage, the need for shunt operation was higher in groups 2 and 3 than in group 1.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1432-2099
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 1432-2013
    Schlagwort(e): Cardiac myocytes ; ATP-sensitive K+ current ; K+ accumulation ; Nicorandil ; T-tubules
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The mechanism of nicorandil-induced large inward tail current (I tail) in single guinea-pig ventricular cells was investigated using the whole-cell patch-clamp technique. In the presence of 0.5–1.0 mM nicorandil, an activator of adenosine 5′-triphosphate (ATP)-sensitive K+ current (I KATP), a depolarization pulse causing a large outward current was followed by a large inward I tail on the repolarization step to the holding potential at-85 mV. The larger the outward current, the greater the I tail. The amplitude of I tail increased as a single exponential function (τ=74.9 ms) as the duration of preceding depolarization was prolonged. Both the outward current and I tail were inhibited nearly completely after application of glibenclamide (1 μM), a specific blocker of I KATP. Substitution of K+ with Cs+ in both the external and internal solutions resulted in a virtual elimination of I tail. I tail was well preserved under the condition where Ca2+ entry during the preceding depolarization was largely inhibited or where external Na+ was replaced by Li+. A transient positive shift of reversal potential for the net current was observed at the peak of I tail. At 30 mM external K+ concentration, I tail was almost eliminated. From these findings, it is concluded that the I tail is a K+ current associated with an alteration of the K+ equilibrium potential (E K) following a substantial K+ efflux. This E K change is most likely explained by an accumulation of K+in transverse tubules (T-tubules) since I tail was not induced in atrial cells in which T-tubules are poorly developed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Child's nervous system 7 (1991), S. 327-331 
    ISSN: 1433-0350
    Schlagwort(e): CO2 reactivity ; Autoregulation ; Fetal brain ; Intraventricular hemorrhage
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Intraventricular hemorrhage (IVH) in preterm infants is well known to be associated with the high morbidity and mortality of this group. Previous studies have suggested altered cerebral blood flow (CBF) as an important pathologic factor. We measured the CBF in nearterm rabbit fetuses using the hydrogen clearance technique. The local CBF of the rabbit fetuses was significantly low compared with that of the maternal rabbits. The response of CBF to changes in PaCO2 was observed in rabbit fetuses. The CO2 reactivity index of the fetal rabbit was lower than that of the maternal rabbit. This low CO2 reactivity might reflect the immaturity of the fetal brain and its low CBF. We were unable to monitor the fetal blood pressure, but the fetal CBF remained stable when the maternal blood pressure was altered. It is well known that IVH in preterm infants originates from the subependymal germinal matrix and that this has many fragile vessels. Our observation suggests that even a small increase of CBF during hypercapnia might have a large effect towards producing hemorrhage.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Journal of materials science 10 (1991), S. 1095-1097 
    ISSN: 1573-4811
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Journal of materials science 29 (1994), S. 5773-5778 
    ISSN: 1573-4803
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract In order to improve the surface characteristics of polymethylmethacrylate (PMMA), oxide thin-film coatings were applied using the sol-gel dip-coating technique. The Si(OC2H5)4 (TEOS), CH3Si(OC2H5)3 (MTES) or Ti(O-i-C3H7)4 (TIP) was used as a starting material for SiO2 or TiO2 coating. The hardness of the alkoxy-derived oxide-coated PMMA was increased from 200 MPa for non-coated PMMA with increasing film thickness. By optimizing the heating conditions and the hydrolysis conditions, and by repeating the dip-coating/heating processes, a hardness as high as 325 MPa was achieved in the PMMA triply coated with the TEOS-derived SiO2 film using the withdrawal velocity of 0.30 mms−1 and heat treatment at 80°C. The increase in hardness with the thickness of coating film was saturated before reaching that of bulk silica-dried gel (ca. 500 MPa), which may be due to the increased porous nature of the thick films.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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