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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 10 (1998), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have examined the spatial-frequency selectivity of neurons in areas 17 and 18 of the adult pigmented ferret, by measuring how the amplitude of response depends on the spatial-frequency of moving sinusoidal gratings of optimal orientation and fixed contrast. Neurons in area 17 of the ferret respond optimally to low spatial frequencies [average 0.25 cycles per degree (c/deg)], much lower than the optima for cat area 17. The tuning curves are of the same form as those found in cat and monkey: unimodal with bandwidths in the range 0.8–3.5 octaves. Neurons in area 18 of the ferret respond optimally to even lower spatial frequencies (average 0.087 c/deg) than area 17 neurons, and the distributions of optimal spatial frequency for areas 17 and 18 hardly overlap. In both cortical areas, the bandwidth of the tuning curves is inversely correlated with optimal spatial frequency. This marked difference in tuning between the two cortical areas is probably attributable to differential geniculo-cortical projections. Small injections of fluorescent latex microspheres or horseradish peroxidase (HRP) were made into area 17 or area 18 in order to investigate the populations of geniculate neurons projecting to the two cortical areas. After injections into area 17, labelled neurons are found predominantly in the geniculate A layers, with a few neurons labelled in the C layers. Conversely, after an area 18 injection, similar numbers of labelled neurons are found in the C layers as in the A layers. Soma-size analysis of the neurons in the A-layers suggests the existence of two populations of relay neurons, which project differentially to areas 17 and 18. The different geniculate inputs and the different spatial-frequency tuning in areas 17 and 18 may imply that the two cortical areas process visual information more in parallel than in series.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 18 (2000), S. 595-600 
    ISSN: 1434-6036
    Keywords: PACS. 71.18.+y Fermi surface: calculations and measurements; effective mass, g factor - 71.20.Lp Intermetallic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The Fermi surface of PrNi5 has been studied by the measurements of the de Haas-van Alphen (dHvA) effect at temperatures between 0.3 and in magnetic fields up to 12 T. Two dHvA frequencies have been obtained. The electronic structure of PrNi5 was calculated using the full potential linearized augmented plane wave method. Five sheets of the Fermi surface and the multiple extremal cross sections were determined. First and second sheet have a hole-like structure. The agreement between theory and experiment is obtained by a small downward shift ( 0.1 eV) of the Fermi energy which is probably due to an underestimation of the role of 4 f electrons.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 60 (1982), S. 317-318 
    ISSN: 1432-1440
    Keywords: Adenosine deaminase ; Lymphocytes ; Cell-mediated immunity ; Hodgkin's disease ; Adenosine deaminase ; Lymphozyten ; Zellvermittelte Immunität ; Morbus Hodgkin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Aktivität der Adenosindesaminase (EC3.5.4.4.) ADA in Blutplasma, Erythrozyten und Lymphozyten wurde bei 23 Patienten mit Morbus Hodgkin und teilweise bei 99 Referenzpersonen bestimmt. Die Enzymaktivitäten wurden mit Adenosin als Substrat und durch Analyse des Ammoniaks gemessen. Zwischen den ADA-Aktivitäten in Blutplasma, Erythrozyten und Lymphozyten wurde keine Korrelation festgestellt. Die Lymphozyten der Patienten wiesen niedrigere ADA-Aktivitäten auf als die Lymphozyten der Referenzpersonen. Die ADA-Aktivität in Plasma oder Erythrozyten ist nicht vermindert. Die herabgesetzten ADA-Aktivitäten in den Lymphozyten der Patienten können zur gestörten zellvermittelten Immunantwort bei Morbus Hodgkin in Beziehung gesetzt werden.
    Notes: Summary The activity of adenosine deaminase (ADA) (EC3.5.4.4.) was determined in the blood plasma, erythrocytes, and lymphocytes of 23 patients with Hodgkin's disease and partly also in 99 control subjects. The enzyme activities were measured using adenosine as substrate and by analysis of ammonia. No correlation was found between the ADA activities in lymphocytes, erythrocytes, and blood plasma. The lymphocytes of the patients revealed lower ADA activities (U/g protein) than the lymphocytes of control subjects. The ADA activity is not reduced in plasma or erythrocytes. The lower activities of ADA in the lymphocytes of patients may be related to the impaired cell-mediated immunity of the Hodgkin's disease.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Graefe's archive for clinical and experimental ophthalmology 194 (1975), S. 175-191 
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei einem Patienten trat nach einer Kalkverätzung eine typische Conjunctivitis lignosa auf, die kurz beschrieben wird. An exidiertem Material wurden histologische, elektronen-mikroskopische und histochemische Untersuchungen durchgeführt mit dem Ziel, die morphologische Beschaffenheit des in der Konsistenz knorpelartigen Tumors darzustellen und eine morphologische Beziehung zwischen Mucopolysaccharidbildung und Faserbildung näher zu klären. Der Aufbau des Tumors ließ sich in drei Abschnitte unterteilen: Zone A, die Pseudomembran, die sich mit bälkchenartigen Ausläufern in dem darunterliegenden Gewebe verankert und morphologisch aus teils homogen, teils faserig erscheinendem Material besteht, in das Blutzellen und Zellreste eingeschlossen sind. Auch die histochemische Untersuchung ergab kein einheitliches Bild: neben geringen Mengen von Dermatansulfat und Chondroitinsulfat B enthält die Pseudomembran wahrscheinlich größere Mengen von Hyaluronsäure. An die Pseudomembran grenzt ein Granulationsgewebe (Zone B) an, das durch seine breiten metachromatischen Gefäßscheiden und durch die am Tumorrand besonders zahlreichen und aktiven Fibroblasten auffällt. Die Silberimprägnationsmethode und die elektronen-mikroskopische Untersuchung zeigte, daß die Gefäßscheiden aus Bündeln reticulärer Fasern bestehen, die in den verschiedenen Richtungen des Raumes verlaufen. Auch die Fibroblasten zeigen eine derartige Faserhülle. Die Mucopolysaccharide in der Umgebung der Fasern enthalten als stärkste Fraktion Chondroitinsulfat, das besonders an den Kreuzungsstellen der Fasern auch diffus verteilt vorkommt, während Dermatansulfat bzw. Heparansulfat nur in der Mucopolysaccharidhülle der Fasern selbst enthalten ist. Die tiefe Region C des Tumors besteht fast ausschließlich aus Gefäßen, Gefäßsprossen und Fibroblasten mit ihren breiten Faserhüllen, die damit fast den gesamten Zwischenraum zwischen den Gefäßen ausfüllen. Diese reticulären Fasern mit ihren Mucopolysaccharidhüllen zeigen den gleichen Aufbau wie in Zone B beschrieben. Die Tatsache, daß die Mucopolysaccharide nicht in „Plaques“, sondern hauptsächlich an Fasern gebunden auftreten, läßt vermuten, daß bei der Conjunctivitis lignosa eine Faserbildungsstörung im Vordergrund steht, für die wahrscheinlich die ergastoplasma- und fibril-lenreichen Fibroblasten und Pericyten verantwortlich gemacht werden können. Die knorpelartige Konsistenz könnte auf der Anordnung der Fasern zusammen mit ihrer Mucopoly-saccharidhülle zurückzuführen sein. Kurze Überlegungen über therapeutische Konsequenzen werden angestellt.
    Notes: Summary A case is briefly described in which a typical conjunctivitis lignosa appeared after the eye had suffered lime burns. In order to help clarify the morphological connection between mucopolysaccharide production and fiber development in the tumor tissue which occurred after the burn, samples were examined histologically, histochemically and with the use of the electron microscope. The tumor had a cartilage like consistency. Its structure could be devided into three regions. Region A is the pseudo-membrane. It has root like extensions which anchor it to the underlying tissue, and which morphologically appear partially homogeneous and partially fibrous. Blood cells and cell remnants are included in the tissue of the pseudomembrane. The histochemical examination of the pseudomembrane did not present a uniform picture. Along with small amounts of dermatan-sulfate and chondroitin-sulfate B the membrane probably contained a rather large amount of hyaluronic acid. The pseudomembrane borders on a granular tissue (Region B) which is distinguished by the wide metachromatic sheathes of the blood vessels found in it and the particularly large number of active fibroblasts along its edges. The silver impregnation method and the electronmicroscopic examination showed that the vascular sheathes consist of bundles of reticular fibers which constitute a three-dimensional network. A similar sort of sheath was observed around the fibroblasts. Chondroitin-sulfate makes up the largest fraction of the mucopolysaccharides near the fibers and appears particularly concentrated at the intersections of the fibers, although it is also diffusely distributed as well. Dermatan-sulfate (or heparan-sulfate) is found only in the mucopolysaccharide sheath of the fibers themselves. The deep region of the tumor (Region C) consists almost exclusively of blood vessels, their sprouts and the fibroblasts which, with their wide fibrous sheathes, almost fill the spaces between the blood vessels. The reticular fibers and their mucopolysaccharide sheathes have the same structure as that observed in Region B. The fact that the mucopolysaccharides did not appear in plaques but rather as bound primarily to the fibers is grounds for suggesting that a fiber development disorder, probably stemming from the pericytes and fibroblasts rich in ergastoplasm and fibrilles, could play the principle role in conjunctivitis lignosa. The cartilagen like consistency of the tumor could be a result of the arrangement of the fibers and their mucopolysaccharide sheathes. Brief remarks are included concerning the therapeutic consequences of the study.
    Type of Medium: Electronic Resource
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