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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 3205-3212 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Dielectric potting materials (encapsulants) are used to prevent air breakdown in high-voltage electrical devices. We report breakdown strengths in void-filled encapsulants, stressed with unipolar voltage pulses of the order of 10 μs duration. High strengths, on the order of 100 kV mm−1, are measured under these test conditions. The materials studied include low-density open celled gel-derived foams with cell sizes of 4 μm or less, closed celled CO2-blown polystyrene and urethane foams, and epoxies containing 48 vol % of hollow glass microballoon (GMB) fillers. These last specimens varied the void gas (N2 or SO2) and also the void diameters (tens to hundreds of μm). Our measurements are thought to be directly sensitive to the rate of field-induced ionization events in the void gas; however, the breakdown strengths of the materials tested appeared to vary in direct proportion with the conventional Paschen-law gas-discharge inception threshold, the electric stress at which gas-ionization avalanches become possible. The GMB-epoxy specimens displayed this type of dependence of breakdown strength on the void-gas density and void size, but the measurements were an order of magnitude above the conventional predictions. Small-celled foams also showed increased breakdown strengths with decreased cell size, although their irregular void geometry prevented a direct comparison with the more uniformly structured microballoon-filled encapsulants. The experimental observations are consistent with a breakdown mechanism in which the discharge of a few voids can launch a full breakdown in the composite material. © 2002 American Institute of Physics.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5962-5971 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report breakdown strengths in a void-filled dielectric material, epoxy containing 48 vol % hollow glass microballoon filler, which is stressed with unipolar voltage pulses of the order of 10 μs duration. The microballoon voids had mean diameters of approximately 40 μm and contained SO2 gas at roughly 30% atmospheric pressure. This void-filled material displays good dielectric strength (of the order of 100 kV mm−1) under these short-pulse test conditions. Results from a variety of electrode geometries are reported, including arrangements in which the electric stress is highly nonuniform. Conventional breakdown criteria based on mean or peak electric stress do not account for these data. A statistics-based predictive breakdown model is developed, in which the dielectric is divided into independent, microballoon-sized "discharge cells" and the spontaneous discharge of a single cell is presumed to launch full breakdown of the composite. We obtain two empirical parameters, the mean and standard deviation of the spontaneous discharge field, by fitting breakdown data from two electrode geometries having roughly uniform fields but with greatly differing volumes of electrically stressed material. This model accounts for many aspects of our data, including the inherent statistical scatter and the dependence on the stressed volume, and it provides informative predictions with electrode geometries giving highly nonuniform fields. Issues related to computational spatial resolution and cutoff distance are also discussed. © 2002 American Institute of Physics.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 82 (2002), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The motor signs of Parkinson's disease have been partly attributed to an overinhibition of the external globus pallidus (GP) that results from hyperactivity of striatopallidal GABA/enkephalinergic neurons. The goals of this study were to measure basal levels of extracellular fluid GABA in the GP of normal cats, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated parkinsonian cats and cats spontaneously recovered from MPTP-induced parkinsonism, and to examine the effects of opioid receptor activation on potassium (K+)-evoked GABA release in the GP in these animals. Basal GP GABA levels were increased 75% from normal in parkinsonian animals 1 week after MPTP administration and returned to control levels in recovered animals 6 weeks afterMPTP administration. No significant differences were observed in K+-evoked GABA release across conditions. The opioid receptor agonist [D-Ala2]-Met-Enkephalinamide (DALA) significantly attenuated K+-evoked GABA release in the GP of MPTP-treated symptomatic and recovered cats, but had no significant effect on GABA release in normal animals. These data show that basal GP GABA levels are elevated coincident with expression of parkinsonian signs and return to normal in animals that have functionally compensated for a nigrostriatal lesion. DALA-induced inhibition of pallidal GABA release after a dopamine-depleting lesion, suggests that enkephalin may attenuate GABA release in the GP specifically after striatal dopamine loss.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Clinical & experimental allergy 31 (2001), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Desloratadine is a non-sedating, clinically effective, anti-allergic therapy that has been shown to exhibit anti-inflammatory properties that extend beyond its ability to antagonize histamine at H1-receptor sites. This latter effect has been shown in vitro to be both IgE-dependent and -independent.Objective In this study, we addressed the ability of desloratadine to inhibit the in vitro generation of interleukin (IL)-4 and IL-13 from human basophils while concurrently comparing its efficacy in preventing mediator release by these cells.Methods Basophil-enriched suspensions were treated with various concentrations of desloratadine for 15 min before stimulating with either anti-IgE antibody, calcium ionophore, IL-3 or phorbol ester. Histamine (fluorimetry), LTC4 (RIA) and IL-4 (ELISA) were all assayed using the same 4-h culture supernatants. IL-13 (ELISA) was measured in supernatants harvested after 20 h incubation. IL-4 mRNA expression (dilutional RT-PCR) was also examined.Results Desloratadine was found to be nearly six–seven times more potent in preventing the secretion of IL-4 and IL-13 induced by anti-IgE than it was at inhibiting the release of histamine and LTC4. These cytokines were equally inhibited by desloratadine following activation with ionomycin despite the lack of an effect on the histamine induced with ionomycin. Desloratadine had a lesser effect regarding inhibition of the IL-13 secreted in response to IL-3 and PMA. There was no evidence that desloratadine mediated its inhibitory effects by causing decreased cell viability. Finally, IL-4 mRNA accumulation was remarkably inhibited, by as much as 80%, following pretreatment with desloratadine.Conclusion While capable of inhibiting histamine and LTC4 release by human basophils, desloratadine is more effective at targeting the signals regulating IL-4 and IL-13 generation in these cells. This inhibitory effect on cytokine generation provides additional evidence that this antihistamine exerts anti-inflammatory properties.
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  • 5
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background The complex interactions between immune cells are partly mediated by different adhesion molecules, but little is known about their role in the systemic immunoinflammatory process following sensitization to food antigens in early infancy.Objective The aim of this study was to investigate the expression of intercellular adhesion molecule-1 (ICAM-1or CD54) and the α subunits of its ligands' lymphocyte function-associated antigen-1 (LFA-1) (αL subunit or CD11a) and Mac-1 (αM subunit or CD11b) on peripheral blood leucocytes in infants with cow's milk allergy (CMA) and in healthy controls.Methods Thirty-nine breastfed infants, aged from 0.6 to 8.3 months, and their lactating mothers were included in the study from delivery onwards. During follow-up, 25 infants developed CMA and 14 remained healthy. Expressions of CD54 and CD11b on peripheral blood leucocytes were evaluated by flow cytometry. In addition, the expression of CD11a on peripheral blood leucocytes was analysed by immunocytochemistry. Mothers' milk samples were collected and their leucocyte content was evaluated using a light microscope.Results The frequency of ICAM-1 expressing peripheral blood lymphocytes was significantly higher in patients with CMA than in healthy infants (P=0.03, Mann–Whitney U-test). Furthermore, the high proportion of ICAM-1-expressing cells was associated with gastrointestinal and multiorgan symptoms in the CMA infants. There was no significant difference in the expression of Mac-1 αM on lymphocytes in our study groups, but the LFA-1 αL expression seemed to be higher in the IgE-mediated CMA.Conclusion We suggest that the high expression of ICAM-1 on peripheral blood lymphocytes may reflect enhanced stimulation of T cells in vivo and their migration to the effector tissues in an early-phase of developing CMA. Furthermore, high ICAM-1 expression may be associated with the presence of multiorgan manifestations of CMA, whereas high LFA-1 expression may reflect the IgE-mediated disease.
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  • 6
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Experimental dermatology 10 (2001), S. 0 
    ISSN: 1600-0625
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Dendritic cells seem to be of major importance for the pathogenesis of psoriasis. They are increased in number in lesional psoriatic skin which is thought to be due to an increased influx from the peripheral blood regulated by chemotaxins. Using a biological/biochemical approach we have addressed the question whether psoriasis scale extracts contain proteinaceous chemotaxins for dendritic cells. Human monocytes differentiated into dendritic cells by culture with GM-CSF and IL-4 (MoDC) served as responder cells. Chemotactic activity for MoDC was purified by several HPLC-steps. The results of our study show that C5a/C5adesarg is the major chemotactic peptide for MoDC in psoriasis scale extracts. In comparison to other stimuli such as fMLP or monocyte chemotactic peptide 1 (MCP-1) C5a proved to be a most potent and efficient chemotaxin for MoDC. C5a co-eluted with MRP14/calgranulin B which is present in large amounts in psoriasis scale extracts as identified by amino acid sequencing. However, MRP14/calgranulin B did not possess any chemotactic activity for MoDC. Our results provide evidence that C5a/C5adesarg although not specific for dendritic cells seems to be the major chemoattractant for these cells in lesional psoriasis skin.
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  • 7
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Experimental dermatology 9 (2000), S. 0 
    ISSN: 1600-0625
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The etiology and pathogenesis of psoriasis – one of the most common chronic, inflammatory, hyperproliferative skin disorders of man – have long fascinated dermatologists, pathologists and biologists alike. Here, we have a model disease that offers to study neuroectodermal-mesenchymal interactions in the widest sense possible. Epithelial, endothelial, and hematopoietic cells as well as neurons projecting into the skin apparently all interact with each other to generate the characteristic psoriatic lesion. For decades, the ongoing controversy on the molecular nature, choreography and hierarchy of these complex interactions e.g. between epidermal keratinocytes, T cells, neurotrophils, endothelial cells and sensory nerves has served as a driving force propelling investigative dermatology to ever new horizons. This debate has not only been at the heart of our quest to develop more effective forms of therapy for this socially crippling disease, but it also has profoundly influenced how we view the skin as a whole: the numerous competing theories on the pathogenesis of psoriasis published so far also are reflections on the evolution of mainstream thought in skin biology over the last decades. These days, conventional wisdom – infatuated with a T-cell-centered approach to inflammatory skin diseases – portrays psoriasis as an autoimmune disease, where misguided T lymphocyte activities cause secondary epithelial abnormalities. And yet, as this CONTROVERSIES feature reminds us, some authoritative “pockets of academic resistance” are still quite alive, and interpret psoriasis e.g. as a genetically determined, abnormal epithelial response pattern to infectious and/or physicochemical skin insults. Weighing the corresponding lines of argumentation is not only an intriguing, clinically relevant intellectual exercise, but also serves as a wonderful instrument for questioning our own views of the skin universe and its patterns of deviation from a state of homeostasis.
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  • 8
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] We report missense mutations in the mitochondrial fusion protein mitofusin 2 (MFN2) in seven large pedigrees affected with Charcot-Marie-Tooth neuropathy type 2A (CMT2A). Although a mutation in kinesin family member 1B-β (KIF1B) was associated with CMT2A in a single Japanese family, we ...
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Allergy 57 (2002), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: To gain insight into the mechanisms responsible for tissue neutrophil immigration in sinusitis, primary nasal fibroblasts are analyzed for synthesizing and delivering neutrophil chemokines.Methods: Primary nasal fibroblast cell culture was treated with tumor necrosis factor (TNF)-α concentrations of 20 and 200 ng/ml for 2, 8, 24 and 72 h. Chemokine concentrations in supernatants were determined by enzyme-linked immunoassay (ELISA) and chemokine mRNA expression in fibroblasts was measured by reverse transcriptase polymerase chain reaction (RT-PCR). Biological chemotactic activity was identified by three-step high-performance liquid chromatography (HPLC) and by bioassay measuring neutrophil chemotaxis in a single Boyden chamber system.Results: Interleukin (IL)-8 and growth-related oncogene (GRO)-α were induced in nasal fibroblast culture by proinflammatory stimulus. After 24 h of stimulation neutrophil chemotactic activity only was detected for IL-8. Granulocyte chemotactic protein (GCP)-2 mRNA was already significantly up-regulated after 2 h of stimulation.Conclusion: Induction of IL-8 protein dominates chemokine synthesis 24 and 72 h after stimulation, whereas induction of GCP-2 mRNA seems to have a role in the early phase after 2 h of exposition with TNF-α.
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  • 10
    ISSN: 1434-3932
    Keywords: Schlüsselwörter  Apoplexie ; Karotis-TEA ; Karotisstenting ; Neuromonitoring ; Embolie ; Transkranielle Dopplersonographie ; Key words Stroke ; Carotid TEA ; Carotid stenting ; Neuromonitoring ; Emboli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract  In a retrospective study we examined whether it is possible to achieve better results in carotid artery surgery with a new operative technique called ”no-touch-isolation technique” in combination with intraoperative angiography than with conventional operative techniques. Patients and methods: In 1997 and 1998, 80 patients who were operated on using this new operative technique were compared with a group of 144 patients who had undergone conventional carotid endarterectomy. The new aspect of the no-touch-isolation technique is that the whole operation strategy aims to avoid possible intraoperative and postoperative embolism. At first, the internal carotid artery is exposed and clamped distally to the stenotic plaque very atraumatically. The operation was then continued without an intraluminal shunt. At the end of the operation the result was checked by means of an intraoperative angiography. If any suggestion of a possible embolism, such as tears of the intima, were seen, an intraoperative revision was carried out until all thrombembolic material was removed. Results: The two groups were not different regarding age, sex, symptoms, degree of stenosis and risk factors nor did any significant differences exist in the operative technique used for endarterectomy (with or without patch, eversions-TEA, etc.). The group operated on with the no-touch-isolation technique had significantly longer operation- times (110 min vs 90 min) and also significantly longer clamping times (38.7 min vs 28.2 min) than the group operated on using conventional technique. The postoperative results, however, were still better. There were significantly fewer neurological deficits (4.1% vs 9.3%). Conclusion: The no-touch-isolation technique in combination with intraoperative angiography is a very safe method of treatment in patients with symptomatic stenosis of the internal carotid artery with a more than 70% degree of stenosis.
    Notes: Zusammenfassung  In einer retro-spektiven Studie wurde untersucht, inwieweit sich mit einer Optimierung der Operationstechnik an der A. carotis, der sog. No-touch-isolation-Technik, bessere Ergebnisse erzielen lassen. 80 Patienten, die 1997 und 1998 in der neuen Technik operiert worden waren, wurden mit einer Gruppe von 144 Patienten, die zuvor in herkömmlicher Technik operiert worden waren, verglichen. Das Neue der No-touch-isolation-Technik bestand darin, dass die ganze Operationstaktik darauf abzielte, mögliche intraoperative und postoperative Embolien zu vermeiden. Zu diesem Zweck wurde als Erstes die A. carotis interna ganz atraumatisch freigelegt und distal des stenosierenden Plaques abge-klemmt. Anschließend erfolgte die weitere Operation ohne Einlage eines intraluminären Shunts. Am Ende der Operation wurde das Ope-rationsergebnis mittels einer intra-operativen Angiographie kontrol- liert. Wenn sich dabei mögliche übriggebliebene Embolisationsquellen, wie Intimalefzen zeigten, erfolgte eine intraoperative Revision, bis alle Embolisationsquellen besei-tigt waren. Die beiden verglichenen Gruppen unterschieden sich nicht bezüglich Alter, Geschlecht, Sympto-matik, Stenosegrad und Risikofaktoren. Auch bezüglich der angewandten Operationsverfahren (TEA mit oder ohne Patch, Eversions-TEA etc.) bestanden keine signifikanten Unterschiede. Die in No-touch-isolation-Technik operierte Gruppe hatte signifikant längere Operationszeiten (110 vs. 90 min) und auch signifikant längere Abklemmzeiten (38,7 vs. 28,2 min) als die in der herkömmlichen Technik operierte Gruppe. Die perioperativen Ergeb-nisse waren jedoch besser. So traten signifikant weniger neurologische Defizite auf (4,1 vs. 9,3%). Die No-touch-isolation-Technik in Verbindung mit einer intraoperativen Angiographie ist eine Methode mit einer sehr geringen Insultrate bei Patienten mit symptomatischen 〉70%igen Karotisstenosen.
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