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  • 1
    Electronic Resource
    Electronic Resource
    The Susceptibility of Cerebral Endothelial Cells to Astroglial Induction of Blood-Brain Barrier Enzymes Depends on Their Proliferative State (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 57 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Primary cultures of brain capillary endothelial cells (BCECs) were used to investigate the induction of blood-brain barrier (BBB) characteristics in vitro. Enzymatic activities of γ-glutamyltranspeptidase (γ-GT) and alkaline phos-phatase (ALP) were taken as indicators for the expression of the BBB phenotype. We were able to show that a coculture system with a direct cell-cell contact between astroglial cells and BCECs is the necessary precondition for an increase of these enzyme activities that are lost in pure BCEC cultures. Coculture with both astrocytes and C6-glioma cells reestablishes the BBB phenotype whereas conditioned media as well as an astrocyte-derived extracellular matrix were ineffective. The susceptibility of the BCECs to an astroglial stimulus depends on the proliferative state of the BCECs. Cells in an early highly proliferate culture phase were stimulated to express an enzymatic activity level similar to the in vivo situation. Confluent BCEC monolayers were not induced at all. With the ALP we observed a spatial induction within a BCEC colony. Astrocyte-induced ALP activity was first observed at an outer belt of BCEC colonies in direct contact with the astrocyte layer. However, this signal is transferred to the center of the colony with time in culture. We conclude that direct contact of BCECs with astroglial cells is necessary for the induction of the BBB phenotype in cultured BCECs and that this signal may be transferred from induced to noninduced BCECs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb06411.x
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  • 2
    Electronic Resource
    Electronic Resource
    Cardiac Output Is Not Affected During Intraoperative Testing of the Automatic Implantable Cardioverter Defibrillator (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 7 (1996), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Cardiac Output and ICD Implantation. Introduction: Perioperative mortality of patients undergoing implantation of automatic implantable cardioverter defibrillators (ICDs) has been reduced dramatically following the availibility of trans venous-subcutaneous defibrillation leads. However, patients with severely reduced left ventricular function show a substantial rate of nonsudden cardiac mortality within the first year. Whether repeated intraoperative inductions of ventricular tachycardia/fibrillation (VT/VF) during implantation lead to hemodynamic deterioration and thus might contribute to development of end-stage heart failure in these patients is unknown. The purpose of the present study was to determine cardiac output and hemodynamic performance during transvenous-subcutaneous ICD implantation in patients with severe left ventricular dysfunction. Methods and Results: In 11 patients with a left ventricular ejection fraction (EF) ≤ 0.35, cardiac output was measured automatically with a combined continuous cardiac output/mixed venous oxygen saturation pulmonary artery catheter system. ICD implantation was performed during standardized general anesthesia. In the 11 patients (EF = 27 ± 2% [mean ± SEM]) a total of 95 episodes of VT/VF followed by defibrillation were induced (epsiodes per patient = 9 ± 1; range 6 to 11). Cardiac index was 2.2 ± 0.2 L·min-1·min-2 after induction of anesthesia (before start of surgery), and 1.9 ± 0.1 L·min-1·m-2 immediately before first induction of VT/VF. After the last episode of VT/VF, cardiac index was 2.1 ± 0.2 L·min-1·m-2. Cardiac index measured 1, 2, and 3 minutes after induction of VT/VF was not significantly different when compared to the preinduction value during any episode of VT/VF induction. Similarly, stroke volume index was 39 ± 5 mL·m-2 immediately before first induction of VT/VF and 36 ± 3 mL·m-2 after the last episode of VT/VF (NS). At the end of surgery, hemodynamic parameters did not exhibit any significant difference when compared to the data obtained before start of ICD implantation and testing. Conclusion: Extensive defibrillation tests during transvenous-subcutaneous ICD implantation in patients with severe left ventricular dysfunction are not associated with acute deterioration of cardiac performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1996.tb00518.x
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of RGD peptide coating of titanium implants on periimplant bone formation in the alveolar crest (2002)
    Oxford, UK : Blackwell Science, Ltd
    Clinical oral implants research 13 (2002), S. 0 
    Details
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The aim of the present study was to analyse the effect of organic coating of titanium implants on periimplant bone formation and bone/implant contact. Three types of implants were used: (i) Ti6Al4V implants with polished surface (control 1) (ii) Ti6Al4V implants with collagen coating (control 2) (iii) Ti6Al4V implants with collagen coating and covalently bound RGD peptides. All implants had square cross-sections with an oblique diameter of 4.6 mm and were inserted press fit into trephine burr holes of 4.6 mm in the mandibles of 10 beagle dogs. The implants of five animals each were evaluated after a healing period of 1 month and 3 months, during which sequential fluorochrome labelling of bone formation was performed. Bone formation was evaluated by morphometric measurement of the newly formed bone around the implant and the percentage of implant bone contact. After 1 month there was only little bone/implant contact, varying between 2.6 and 6.7% in the cortical bone and 4.4 and 5.7% in the cancellous bone, with no significant differences between the three types of implants. After 3 months, implants with polished surfaces exhibited 26.5 and 31.2% contact in the cortical and cancellous bone, respectively, while collagen-coated implants had 19.5 and 28.4% bone contact in these areas. Implants with RGD coating showed the highest values with 42.1% and 49.7%, respectively. Differences between the surface types as such were not significant, but the increase in bone/implant contact from 1 to 3 months postoperatively was significant only in the group of RGD-coated implants (P = 0.008 and P = 0.000). The results of this pilot study thus provide only weak evidence that coating of titanium implants with RGD peptides in the present form and dosage may increase periimplant bone formation in the alveolar process. The results therefore require further verification in a modified experimental setting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0501.2002.130312.x
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  • 4
    Electronic Resource
    Electronic Resource
    Midline granuloma presenting as orbital cellulitis (1996)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 234 (1996), S. 137-139 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract ⊎ Background: Lethal midline granuloma usually presents with rhinorrhoea and redness of the skin above the nose. Early ocular symptoms are very rare. We here describe a patient who presented with acute orbital cellulitis. ⊎ Patient: A 73-year-old woman had a 24-h history of severe pain around her left eye. We saw the typical clinical picture of orbital cellulitis. A CT scan revealed a diffuse infiltration of the left upper and lower lid, the anterior orbit and the ethmoidal sinuses. ⊎ Result: On surgical exploration we found a granular, partly necrotic tumour. Histological examination revealed an angiocentric nasal T-cell lymphoma (midline granuloma). ⊎ Conclusion: Midline granuloma should be included in the differential diagnosis of acute orbital cellulitis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00695254
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  • 5
    Electronic Resource
    Electronic Resource
    Visual field defects in optic neuritis and anterior ischemic optic neuropathy: distinctive features (1998)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 236 (1998), S. 188-192 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract • Background: We analyzed the value of visual field defects in the differential diagnosis of optic neuritis (ON) and non-arteritic anterior ischemic optic neuropathy (AION). • Methods: Ninety-nine consecutive patients with acute-onset optic neuropathy formed the basis for this study. Compressive and vasculitic neuropathies were excluded. Eighty-six patients fulfilled the criteria for either ON (50 patients): ≤ 35 years, normal disk, recovery of visual function, or AION (36 patients): ≥ 60 years, swelling of the disk, no recovery of visual function. Without knowledge of other clinical data, visual fields obtained by Goldmann perimetry were classified into five types of defects (forced choice). With the correct diagnosis at hand, fields were reviewed for characteristic features. • Results: Forced-choice classification into defect types [%]: Central scotoma ON 68, AION 18; superior altitudinal defect ON 13, AION 7; inferior altitudinal defect ON 8, AION 52; peripheral defect ON 1, AION 5; diffuse defect ON 10, AION 18. Search for pathognomonic defects: A scotoma centered on the fixation point with a sloping border occurred exclusively in ON (25 of 50 patients). An inferior altitudinal defect with a sharp border along the horizontal meridian, particularly in the nasal periphery, occurred only in AION (10 of 36 patients). A steep centrocecal scotoma occurred in 3 of the 36 AION cases and not at all in the ON cases. Scotomas in the center breaking through to the periphery, superior altitudinal defects (with a sloping border along the horizontal meridian) and diffuse depressions verging on blindness occurred in both ON and AION. • Conclusion: A scotoma centered on the fixation point with a sloping border is highly characteristic of ON, while an inferior altitudinal defect with a sharp border along the horizontal meridian, particularly in the nasal periphery, is highly characteristic of AION. To identify these diagnostic criteria, it can be necessary to examine full fields. With restriction of perimetry to 30° a large central scotoma can be mistaken for a diffuse defect and the border in the nasal periphery can be missed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004170050062
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  • 6
    Electronic Resource
    Electronic Resource
    Proper and normal solutions of the Fokker-Planck equation (1981)
    Springer
    Archive for rational mechanics and analysis 76 (1981), S. 193-246 
    Details
    ISSN: 1432-0673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280460
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  • 7
    Electronic Resource
    Electronic Resource
    Hängt der Fundus-perimetrisch bestimmte Rand des blinden Flecks von der Oberflächenform der Papille ab? (1997)
    Springer
    Der Ophthalmologe 94 (1997), S. 360-363 
    Details
    ISSN: 1433-0423
    Keywords: Key words Scanning laser tomography ; Scanning laser ophthalmoscope ; Fundus perimetry ; Optic disc type ; Schlüsselwörter Scanning-Laser-Tomographie ; Scanning-Laser-Ophthalmoskop ; Fundusperimetrie ; Papillentyp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Fragestellung: Wir wollten herausfinden, ob die Form der Papillenoberfläche die Lage der Außengrenzen bzw. die Größe des blinden Flecks beeinflußt. Patienten und Methode: Wir untersuchten 10 Augen mit einem temporalen parapapillaren Konus (und flacher temporaler Exkavation der Papille) und als Kontrollgruppe 6 Augen ohne Konus. Die Kontrollaugen wiesen keine oder eine ,,normale`` zentrale Exkavation auf. Mittels Fundusperimetrie mit dem Scanning-Laser-Ophthalmoskop (SLO) untersuchten wir die Lichtunterschiedsempfindlichkeit (LUE) entlang des horizontalen Meridians der Papillen. Die Oberflächenform der Papillen wurde mit dem Heidelberg-Retinatomographen (HRT) bestimmt. Ergebnisse: Stimuli mit hoher Leuchtdichte (Goldmann IV, 4 dB) wurden in den 10 Augen mit Konus nur bis 0,8° innerhalb des temporalen Rands des Konus, aber bis 1,9° innerhalb des nasalen Papillenrands gesehen. Diese Papillen hatten immer einen prominenten nasalen Papillenrand im Gegensatz zu einer flachen Exkavation temporal. Eine solche nasotemporale Asymmetrie, weder bezüglich der Struktur noch bezüglich der Funktion, konnte bei keinem der 6 Kontrollaugen nachgewiesen werden. Schlußfolgerung: Die Größe eines Skotoms hängt auch von der Oberflächenform des getesteten Gebiets ab. Prominente Anteile der Papille erscheinen weniger blind als flache Anteile, wahrscheinlich weil sie Licht auf empfindliche benachbarte Netzhautanteile streuen.
    Notes: Background: We wanted to find out whether the borders of the blind spot depend on the surface topography of the optic disc and its surrounding area. Patients and methods: We therefore examined ten eyes with parapapillary atrophy adjacent to the temporal side of the disc. Fundus perimetry was performed under direct fundus control using a Rodenstock scanning laser ophthalmoscope. We examined the horizontal meridian of the optic discs in 0.5° steps using Goldmann IV-stimuli with 10 different degrees of brightness and the Goldmann stimulus I, 0 dB (greatest luminance). Six eyes with symmetric, ,,normal`` excavation served as controls. Optic disc topography was measured with the Heidelberg Retina Tomograph (HRT). Results: Stimuli with a large luminance power (Goldmann IV, 4 dB) were seen up to 0.8° centrally (i. e., towards the optic disc center) from the temporal edge of the parapapillary atrophy, but up to 1.9° centrally from the nasal optic disc border (P〈0.01). Horizontal HRT section profiles of the optic disc consistently showed prominent nasal disc borders contrasting with a shallow excavation within the temporal parapapillary atrophy. In all six subjects with a normally shaped disc there was no such ,,naso-temporal asymmetry.`` Conclusions: The size of scotomas depends on the surface topography of the tested area. The prominent nasal part of the optic disc appears less ,,blind`` than the shallow temporal part, probably due to more intensive light scattering by the prominent nasal part of the disc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003470050129
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  • 8
    Electronic Resource
    Electronic Resource
    Shadow generation for volumetric data sets (1998)
    Springer
    The visual computer 14 (1998), S. 83-94 
    Details
    ISSN: 1432-2315
    Keywords: Key words: Volume visualization ; Scientific visualization ; Medical imaging ; Shadow Z-buffer ; Shadow map
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Z -buffer technique for fast and efficient shadow generation. Volumetric data contain information about the grid points only. Such data do not provide surface information that could be projected immediately onto the shadow map. To solve this problem, we have implemented two techniques. The first uses a modified adaptive version of the well-known marching cubes algorithm for the special characteristics of medical data sets. The algorithm uses material properties for a precise representation of object boundaries, generating volumetric objects quickly and effectively. There are two representations of the same data set: we use a view-independent approximation to display shadows and the original representation of the volume for object visualization in full precision. The second algorithm uses a ray-tracing approach to create shadow maps. The same routine is used for object rendering, but is restricted to depth-value generation. Semitransparent objects are handled by storing an intensity profile in addition to the depth value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003710050125
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  • 9
    Electronic Resource
    Electronic Resource
    Molecular ion implantation in silicon (1997)
    Springer
    Microchimica acta 125 (1997), S. 313-316 
    Details
    ISSN: 1436-5073
    Keywords: molecular ion implantation ; silicon nitride layers ; resonant nuclear reaction analysis ; non-Rutherford RBS ; nitrogen depth profile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 15N2 + molecular ions were implanted with 10keV (j=10 μA/cm2) under high vacuum conditions close to room temperature in 〈100〉 silicon (c-Si) to study the13N depth distributions, particularly the dependence of peak concentration and dose on the ion fluence. The analysis were performed by the resonant nuclear reaction15N(p, αγ)12C(NRA). A maximum peak concentration of 65 at.% was measured. Thin stoichiometric silicon nitride layers with a thickness of approx. 20 nm (15 at.% nitrogen at the specimen surface) were produced by this low-energy implantation of15N2 + ions with an ion fluence of 1.5·1017 ions/cm2. NRA analysis of 38 keV15N2 + and 19keV15N+ ion implantations were performed to compare the15N depth distributions. No significant changes in the depth distributions are measured, that means, the molecular15N2 + ions are already disintegrated passing the very first atomic layers of the sample during implantation. Non-Rutherford RBS with4He+ ions and 3.45 MeV was performed in order to confirm the results obtained by NRA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01246204
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  • 10
    Electronic Resource
    Electronic Resource
    Nitrogen depth distribution, interface and structure analysis of SiNx layers produced by low-energy ion implantation (1997)
    Springer
    Microchimica acta 125 (1997), S. 337-341 
    Details
    ISSN: 1436-5073
    Keywords: ion implantation ; silicon nitride layers ; TEM analysis ; resonant nuclear reaction analysis ; nitrogen depth profile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thin silicon nitride (SiN x ) layers with the stoichiometric N/Si ratio of 1.33 in the maximum of the concentration depth distributions of nitrogen were produced by implanting 10 keV15N 2 + in 〈100〉 silicon at room temperature under high vacuum conditions. The depth distribution of the implanted isotope was measured by resonance nuclear reaction analysis (NRA), whereas the layer structure of the implanted region and the geometrical thickness of the layers were characterised by high resolution transmission electron microscopy (TEM). SiN x layers with a thickness of about 30 nm were determined by NRA. Channeling Rutherford backscattering spectrometry was used to determine the disorder in the silicon substrate. Sharp interfaces of a few nanometers between the highly disordered implanted region and the crystalline structure of the substrate thickness were observed by TEM. The high thermal stability of SiN x layers with N/Si ratios from under to over stoichiometric could be shown by electron beam rapid thermal annealing (1100 °C for 15 s, ramping up and down 5 °C/s) and NRA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01246208
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