Bibliothek

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • Node of Ranvier  (4)
  • sol-gel  (4)
  • Electron microscopy  (3)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Der Pathologe 16 (1995), S. 404-407 
    ISSN: 1432-1963
    Schlagwort(e): Schlüsselwörter Nerval-neuroendokriner Komplex ; Zollinger-Ellison-Syndrom ; Magenschleimhaut ; Elektronenmikroskopie ; Key words Nerve fibre-neuroendocrine cell complex ; Stomach ; Zollinger-Ellison-Syndrom ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Nerve fibre-neuroendocrine cell complexes (NF-NEC-C's) are neuroendocrine cells located in the lamina propria of the gastrointestinal tract directly connected with nerve fibres of Meissner's plexus. We report on a patient with sporadic Zollinger-Ellison syndrome (ZES) with electron microscopically demonstrated multiple NF-NEC-C's in non-antral gastric mucosa. It is suspected that in ZES the hypergastrinaemia may represent a trophic stimulus for the proliferation of NF-NEC-C's in the gastric mucosa.
    Notizen: Zusammenfassung Unter nerval-neuroendokrinen Komplexen (N-NE-K) versteht man in der Lamina propria mucosae des Magen-Darm-Traktes gelegene Nester neuroendokriner Zellen, die in direktem Kontakt zu Nervenfasern des Meissner-Plexus stehen. Es wird über einen Patienten mit sporadischem Zollinger-Ellison-Syndrom (ZES) berichtet, bei dem sich elektronenmikroskopisch in nonantraler Magenschleimhaut multiple N-NE-K fanden. Möglicherweise stellt die Hypergastrinämie bei ZES einen trophischen Stimulus für die Proliferation von N-NE-K in der Magenschleimhaut dar.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 349 (1974), S. 133-148 
    ISSN: 1432-2013
    Schlagwort(e): Node of Ranvier ; Sodium Permeability ; Aconitine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effect of aconitine (10−5–10−6 g/ml) on membrane potentials and membrane currents of myelinated nerve fibres of Xenopus laevis was investigated. The following observations were made: a) Current clamp conditions: Slow depolarization (10–15 mV), decrease of amplitude and maximum rate of rise of action potential, finally inexcitability. With inward current pulses ‘hyperpolarizing responses’ could be elicited at membrane potentials more negative than the resting potential (E r ). Neither spontaneous activity nor repetitive responses to electrical stimuli were observed. No effects of aconitine were found in Na-free solutions or in the presence of tetrodotoxin. b) Voltage clamp conditions: Development of steady inward current at normal resting potential due to formation of a non-inactivating sodium permeability; heavily poisoned nodes therefore exhibit an N-shaped steady-state current voltage relation with negative slope at membrane potentials more negative thanE r . These non-inactivating sodium channels open more slowly than normal sodium channels, and can only be closed by hyperpolarizing the membrane by about 50 mV. The majority of sodium channels have almost normalτ m; theirm ∞ andh ∞-V relations are shifted by 10–15 mV towardsE r . It is concluded that these changes of the sodium permeability account for the changes of electrical activity observed after treatment with aconitine.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 303 (1968), S. 133-149 
    ISSN: 1432-2013
    Schlagwort(e): Node of Ranvier ; Ionic Currents ; Scorpion Venom ; Ranvierscher Schnürring ; Ionenströme ; Skorpiongift
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung 1. Die Wirkung von Skorpiongift (10−6 g/ml) auf die Ionenströme einzelner markhaltiger Nervenfasern von Xenopus laevis wurde in voltage-clamp-Experimenten untersucht. 2. Skorpiongift beeinflußt sowohl die Natrium- als auch die Kalium-Permeabilität der Schnürringmembran. 3. Die hauptsächlichen Wirkungen des Skorpiongiftes auf die Natrium-PermeabilitätP Na sind: a) Die maximale Natrium-Permeabilität $$\bar P_{_{{\rm N}a} } $$ wird auf 60% ihres an der unvergifteten Membran gemessenen Wertes reduziert. b) Die Natriuminaktivierung wird stark verlangsamt und verläuft in zwei Phasen. c) Der zeitliche Verlauf vonP Na kann unter der Annahme beschrieben werden, daß die Variableh aus zwei Komponentenx undy besteht, deren Zeitkonstanten τ x und τ y 4 bzw. 200 mal so groß sind wie τ h der unvergifteten Membran. 4. Die Wirkungen des Skorpiongiftes auf die Kalium-PermeabilitätP K sind: a) Die maximale Kalium-PermeabilitätP K' wird auf etwa 35% ihres Normalwertes vermindert. b) Der Anstieg vonP K bei Depolarisation wird verlangsamt; zwei Phasen können unterschieden werden. 5. Die Wirkungen auf die Natrium-Inaktivierung und auf die Kalium-Permeabilität können die unter dem Einfluß von Skorpiongift beobachtete extreme Verlängerung des Aktionspotentials erklären.
    Notizen: Summary 1. The action of scorpion venom (10−6 g/ml) on the ionic currents of single myelinated nerve fibres of Xenopus laevis was studied in voltage clamp experiments. 2. Scorpion venom was found to affect the sodium permeability as well as the potassium permeability of the nodal membrane. 3. The main effects of scorpion venom on the sodium permeabilityP Na are: a) The maximum sodium permeability $$\bar P_{_{{\rm N}a} } $$ is reduced to 60% of its value in the unpoisoned membrane. b) The sodium inactivation is markedly slowed and proceeds in two phases. c) The time course ofP Na can be described assuming that the variableh is the sum of two componentsx andy, whose time constants τ x and τ y are 4 and 200 times τh of the unpoisoned membrane. 4. The effects of scorpion venom on the potassium permeabilityP K are: a) The maximum potassium permeabilityP K' is reduced to about 35% of its normal value. b) The increase ofP K' upon depolarisation is slowed down; two phases can be distinguished. 5. The effects on sodium inactivation and potassium permeability may explain the extreme prolongation of the action potential under the influence of scorpion venom.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 303 (1968), S. 150-161 
    ISSN: 1432-2013
    Schlagwort(e): Node of Ranvier ; Sodium Inactivation ; Scorpion Venom ; Ranvierscher Schnürring ; Natrium-Inaktivierung ; Skorpiongift
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung 1. Die Wirkung von Skorpiongift auf die Inaktivierung der Natrium-PermeabilitätP Na wurde in voltage-clamp-Experimenten an einzelnen markhaltigen Nervenfasern von Xenopus laevis untersucht. 2. Beim normalen Ruhepotential warP Na der vergifteten Membran stärker inaktiviert als an der unvergifteten Membran; bei starken Depolarisationen war die Inaktivierung jedoch unvollständig. 3. Der zeitliche Verlauf vonP Na konnte unter verschiedenen experimentellen Bedingungen mit den Hodgkin-Huxley-Gleichungen beschrieben werden, die wie folgt modifiziert wurden: a) die Variableh wurde durch eine schnelle Komponentex und eine langsame Komponentey ersetzt; b) die Komponentex nahm selbst bei Depolarisationen von mehr als 40 mV nicht auf Null ab.
    Notizen: Summary 1. The action of scorpion venom on the inactivation of the sodium permeabilityP Na was studied in voltage-clamp experiments on single myelinated nerve fibres of Xenopus laevis. 2. At the normal resting potentialP Na of the poisoned membrane was more inactivated than the control; at large depolarizations inactivation was, however, incomplete. 3. The time course ofP Na under various experimental conditions could be described by theHodgkin-Huxley equations modified as follows: a) the variableh was split into a fast and a slow component (x andy, respectively); b) componentx did not vanish even for depolarizations by more than 40 mV.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular medicine 63 (1985), S. 176-183 
    ISSN: 1432-1440
    Schlagwort(e): Whipple's disease ; Electron microscopy ; Disturbed cellular immunology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Whipple's disease is a curious disorder with the involvement of many organ systems, primarily gut, synovium and the central nervous system, characterized by the presence of numerous proliferating bacteria in tissue macrophages and other cell types. While clinically this disease entity has previously been defined by the classical triad of diarrhoea, malabsorption and weight loss, some patients do not show these features. In this report, a clinically unusual case of Whipple's disease is described presenting with high persistent fever, severe arthralgias and headaches, but without malabsorption, diarrhoea or weight loss. Nevertheless, the histological and electron microscopical pictures demonstrated the typical findings of intracellular micro-organisms along with the presence of bacteria in Schwann nerve cells, which has only once been described previously. Immunological findings before treatment demonstrated a decrease of T cells with the helper/inducer phenotype, and a concomitant rise in cells with the suppressor/cytotoxic phenotype, an elevation of “activated” Ia positive T cells and a significant reduction of T cell mitogenic responsiveness. Of special interest, after a successful treatment these immunological abnormalities shifted to normal with the exception of a still elevated number of Ia+ T cells. The discussion of this unusual case of Whipple's disease includes — besides possible cellular immunological abnormalities — genetic factors, especially since this patient was HLA-B-27-positive as was his son who is suffering from ankylosing spondylitis.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Journal of cancer research and clinical oncology 105 (1983), S. 285-291 
    ISSN: 1432-1335
    Schlagwort(e): Borderline lesion ; Severe dysplasia ; Gastric precancerosis ; Electron microscopy ; Morphometric analysis ; Bleb formation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The “borderline lesion” of the stomach (severe dysplasia of the protruded type) is nowadays considered to be a true precancerous lesion. Histologically, this lesion is characterized by a proliferation in the area of the glandular neck, combined with severe cellular atypia. Investigation by means of transmission electron microscopy reveals the structure of these cells to be very similar to the structure of cells of an intestinal-cell-type carcinoma of the stomach. In addition to signs for a loss of differentiation of the cells, such as the absence of rough-surfaced endoplasmatic reticulum, mucin granules, and of the polarity of the cells, remarkably frequently luminal bulges and “blebs” developed to various extents can be detected. Morphometric analysis is delineating the tendency of structural features of the borderline lesion to develop toward the gastric cancer cell. These irregularities might be expressions of the beginning of expansive growth and signs pointing to differentiation into malignant neoplasia.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 333 (1972), S. 51-61 
    ISSN: 1432-2013
    Schlagwort(e): Node of Ranvier ; Ionic Currents ; Scorpion Venom ; Calcium Ions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Voltage clamp experiments were done on myelinated nerve fibres of Xenopus laevis to study the effect of calcium on the ionic currents of the nodal membrane treated with scorpion venom. Increasing the calcium concentration of the medium from 1.8 to 7.2 mM produced the following changes of the sodium and potassium permeabilities,P Na andP K: a) The incomplete sodium inactivation, which is typical for nodes of Ranvier treated with scorpion venom, is abolished. The curves relatingm ∞ and τ m to membrane potential are shifted by 8–10 mV towards larger depolarizations.P Na and the time constants of the fast and slow components of the sodium inactivation remain practically unchanged. b) The maximum potassium permeability,P K, which is reduced by scorpion venom to 45% of the value observed in the normal node, increases to 68% by addition of calcium ions; τ n is unchanged. These effects of calcium ions on the ionic permeabilities explain the shortening of the extremely prolonged action potential and the inhibition of spontaneous activity observed in nodes of Ranvier poisoned with scorpion venom.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Journal of sol gel science and technology 3 (1994), S. 189-197 
    ISSN: 1573-4846
    Schlagwort(e): nanocomposites ; sol-gel ; heteropolymetalates ; photochromics ; electrochemical properties
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract New nanocomposites materials have been synthesized. They present electrochemical and photochromic properties. They are based on a hybrid organic-inorganic network, in which tungsten heteropolyoxometalates (PW12O 40 3− , SiW12O 40 4− , W10O 32 4− , polymeric tungstate) are entrapped. High tungsten ratios could be reached and films or bulk materials have been obtained. The structure of these materials is described on the basis of multi-spectroscopic investigations (IR, EPR, NMR). Electrochemical redox reactions have been observed in thin films. Dark blue reversible coloration of the materials is obtained under UV irradiation. The photochromic mechanism has been investigated and shows the reversible formation of carbonyl group.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Journal of sol gel science and technology 8 (1997), S. 927-929 
    ISSN: 1573-4846
    Schlagwort(e): organic-inorganic hybrids ; sol-gel ; photochromic performance ; spirooxazine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Organic-inorganic hybrid materials synthesized via sol-gel processing are excellent solid matrices for photochromic dyes like spirooxazine, and the photochromic performance can be further enhanced by introducing suitable additives. This work describes the effects of additives on the photochromic intensity (Δ A 0), decolouration rate (k) and photostability of spirooxazine in sol-gel derived organic-inorganic hybrid matrices. They include fluoro-alkylsilane (FAS), bisphenol A (BPA) and methyl-imidazole (MI). FAS enhances both Δ A 0 and photostability, but has little effect on k. The higher the content of BPA, the higher the Δ A 0 and the higher the photostability, but the lower the k. The effect of MI on Δ A 0 and k is not so considerable as that of BPA and is a little complicated, while significant improvement in photostability is achieved by the addition of MI at an optimum concentration with the presence of BPA at a higher content.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of sol gel science and technology 8 (1997), S. 927-929 
    ISSN: 1573-4846
    Schlagwort(e): organic-inorganic hybrids ; sol-gel ; photochromic performance ; spirooxazine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Organic-inorganic hybrid materials synthesized via sol-gel processing are excellent solid matrices for photochromic dyes like spirooxazine, and the photochromic performance can be further enhanced by introducing suitable additives. This work describes the effects of additives on the photochromic intensity (ΔA 0), decolouration rate (k) and photostability of spirooxazine in sol-gel derived organic-inorganic hybrid matrices. They include fluoroalkylsilane (FAS), bisphenolA (BPA) and methyl-imidazole (MI). FAS enhances both ΔA 0 and photostability, but has little effect onk. The higher the content of BPA, the higher the ΔA 0 and the higher the photostability, but the lower thek. The effect of MI on ΔA 0 andk is not so considerable as that of BPA and is a little complicated, while significant improvement in photostability is achieved by the addition of MI at an optimum concentration with the presence of BPA at a higher content.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...