Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters A 28 (1968), S. 103-104 
    ISSN: 0375-9601
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters A 29 (1969), S. 719-720 
    ISSN: 0375-9601
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 51 (1973), S. 469-471 
    ISSN: 1432-1440
    Keywords: Ferritin labelled antibodies ; immunodiffusion ; sulphide silver reaction ; ferritin-antibody-conjugates ; antigen determination ; Ferritin-gekoppelte Antikörper ; Agargeldiffusion ; Sulfid-Silber-Reaktion ; Ferritin-Antikörper-Komplexe ; Antigennachweis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Dem Nachweis von Antigen-Antikörperpräcipitaten im Agargel sind Grenzen gesetzt, die sich vor allem aus der Konzentration des Antigens in der Untersuchungsprobe ergeben. Geringe Antigenmengen, die bei Anwendung der üblichen Färbemethoden nicht sichtbar werden, lassen sich nur darstellen, wenn die Nachweisempfindlichkeit durch Markierung von Antikörpern gesteigert wird. Als Marker von Antikörpern wurde von uns Ferritin Verwendet, dessen Eisenanteil durch Silberanlagerung (Sulfid-Silber-Reaktion) mit einem Vergrößerungseffekt von mehr als 100 000:1 sichtbar gemacht werden kann. Die Sulfid-Silber-Reaktion ließ sich an luftgetrockneten Agargelpräparaten gut ausführen. Sie eignet sich zur Kontrolle der Ferritinbindung an Antikörper besser als alle früheren Verfahren. Sie führt gleichzeitig zu einer Steigerung der Nachweisempfindlichkeit von Präcipitaten im Agargel. Die bei Routinefärbungen gefundene untere Nachweisgrenze kann um 3–4 Verdünnungsstufen weiter gesenkt werden. Mit Hilfe der Sulfid-Silber-Reaktion lassen sich demnach Antigenmengen erfassen, die dem üblichen Nachweisverfahren entgehen.
    Notes: Summary The demonstration of antigen-antibody precipitations following agar gel diffusion depends on the concentrations of antigen or antibody in the specimen. Small quantities of antigen can only be detected if the sensitivity of the method is increased by marking the antibodies. Ferritin was used as a marker for the antibodies; the single iron molecules are enlarged 100 000 times by the sulphide-silver-reaction and thereby made visible. The sulphide-silver-reaction made it possible to stain precipitation lines in dried agar gel preparations. The method is superior compared to other published data on the analysis of ferritin-antibody conjugates. The sensitivity of the antigen determination is increased for about 3–4 titer steps of dilution. Quantities of antigen can in this way be detected which are otherwise not demonstrable by conventional staining methods.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Effects of 2,5-hexanedione on elemental concentrations and water content of peripheral nerve myelinated axons were determined using electron probe x-ray microanalysis. Axons (small, medium, and large) were analyzed in unfixed cryosections from rat tibial and proximal sciatic nerve samples. Animals were intoxicated with 2,5-hexanedione by two dosing paradigms: intraperitoneal or oral. Regardless of the route of exposure, internodal axoplasm of small and medium axons from both nerve regions exhibited selective, progressive reductions in dry weight K concentrations and water content. When calculated on a wet weight basis, K levels were comparable to or slightly above control values in tibial nerve, whereas in sciatic nerve, small transient decreases in wet weight K were evident. These changes in K and water correlated with the development of axonal atrophy. The wet and dry weight internodal elemental changes reported here do not suggest a metabolic or axolemmal defect, but rather imply a homeostatic response possibly related to the process of axonal atrophy. Giant axonal swellings were primarily associated with oral 2,5-hexane-dione intoxication, and corresponding analyses revealed few changes in element or water content compared with control. The absence of significant alterations in these swellings is consistent with mechanical expansion of the axon probably as a function of accumulating neurofilaments.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: To study mechanisms of K+ transport in peripheral nerve, uptake of rubidium (Rb+), a K+ tracer, was characterized in rat tibial nerve myelinated axons and glia. Isolated nerve segments were perfused with zero-K+ Ringer's solutions containing Rb+ (1–20 mM) and x-ray microanalysis was used to measure water content and concentrations of Rb, Na, K, and Cl in internodal axoplasm, mitochondria, and Schwann cell cytoplasm and myelin. Both axons and Schwann cells were capable of removing extracellular Rb+ (Rb+o) and exchanging it for internal K+. Uptake into axoplasm, Schwann cytoplasm, and myelin was a saturable process over the 1–10 mM Rb+o concentration range, although corresponding axoplasmic uptake rates were higher than respective glial velocities. Mitochondrial accumulation was a linear function of axoplasmic Rb+ concentrations, which suggests involvement of a nonenzymatic process. At 20 mM Rb+o, a differential stimulatory response was observed; i.e., axoplasmic Rb+ uptake velocities increased more than fivefold relative to the 10 mM rate, and glial cytoplasmic uptake rose almost threefold. Finally, Rb+o uptake rate into axons and glia was completely inhibited by ouabain (2–4 mM) exposure or incubation at 4°C. These results suggest that Rb+ uptake into peripheral nerve internodal axons and Schwann cells is mediated by Na+,K+-ATPase activity and implicate the presence of axonal- and glial-specific Na+ pump isozymes.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Electron probe x-ray microanalysis (EPMA) was used to measure water content (percent water) and dry weight elemental concentrations (in millimoles per kilogram) of Na, K, Cl, and Ca in axoplasm and mitochondria of rat optic and tibial nerve myelinated axons. Myelin and cytoplasm of glial cells were also analyzed. Each anatomical compartment exhibited characteristic water contents and distributions of dry weight elements, which were used to calculate respective ionized concentrations. Free axoplasmic [K+] ranged from ≈155 mM in large PNS and CNS axons to ≈120–130 mM in smaller fibers. Free [Na+] was ≈15–17 mM in larger fibers compared with 20–25 mM in smaller axons, whereas free [Cl−] was found to be 30–55 mM in all axons. Because intracellular Ca is largely bound, ionized concentrations were not estimated. However, calculations of total (free plus bound) aqueous concentrations of this element showed that axoplasm of large CNS and PNS axons contained ≈0.7 mM Ca, whereas small fibers contained 0.1–0.2 mM. Calculated ionic equilibrium potentials were as follows (in mV): in large CNS and PNS axons, EK = −105, ENa = 60, and ECl = −28; in Schwann cells, EK = −107, ENa = 33, and ECl = −33; and in CNS glia, EK = −99, ENa = 36, and ECl = −44. Calculated resting membrane potentials were as follows (in mV, including the contribution of the Na+,K+-ATPase): large axons, about −80; small axons, about −72 to −78; and CNS glia, −91. ECl is more positive than resting membrane potential in PNS and CNS axons and glia, indicating active accumulation. Direct EPMA measurement of elemental concentrations and subsequent calculation of ionized fractions in axons and glia offer fundamental neurophysiological information that has been previously unattainable.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: To investigate the route of axonal Ca2+ entry during anoxia, electron probe x-ray microanalysis was used to measure elemental composition of anoxic tibial nerve myelinated axons after in vitro experimental procedures that modify transaxolemmal Na+ and Ca2+ movements. Perfusion of nerve segments with zero-Na+/Li+-substituted medium and Na+ channel blockade by tetrodotoxin (1 µM) prevented anoxia-induced increases in Na and Ca concentrations of axoplasm and mitochondria. Incubation with a zero-Ca2+/EGTA perfusate impeded axonal and mitochondrial Ca accumulation during anoxia but did not affect characteristic Na and K responses. Inhibition of Na+-Ca2+ exchange with bepridil (50 µM) reduced significantly the Ca content of anoxic axons although mitochondrial Ca remained at anoxic levels. Nifedipine (10 µM), an L-type Ca2+ channel blocker, did not alter anoxia-induced changes in axonal Na, Ca, and K. Exposure of normoxic control nerves to tetrodotoxin, bepridil, or nifedipine did not affect axonal elemental composition, whereas both zero-Ca2+ and zero-Na+ solutions altered normal elemental content characteristically and significantly. The findings of this study suggest that during anoxia, Na+ enters axons via voltage-gated Na+ channels and that subsequent increases in axoplasmic Na+ are coupled functionally to extraaxonal Ca2+ import. Intracellular Na+-dependent, extraaxonal Ca2+ entry is consistent with reverse operation of the axolemmal Na+-Ca2+ exchanger, and we suggest that this mode of Ca2+ influx plays a general role in peripheral nerve axon injury.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Pedunculate oak (Quercus robur L.) is known as a strong isoprene (2-methyl-1,3-butadiene) emitter. Diurnal changes in isoprene emission were determined by branch enclosure measurements. In contrast to the diurnal cycle in emission rates, specific isoprene synthase activity in the leaves remained unchanged. Based on in vitro enzyme activity and its temperature dependency, an isoprene synthesis capacity at specific leaf temperatures was calculated. The comparison of these ‘leaf temperature-dependent enzyme capacities’ and the measured emission rates revealed that the enzyme activity of isoprene synthase is comparable to the observed isoprene emission rates. In addition, variation in the isoprene synthase activity of the leaves due to changes in light intensity during leaf development was investigated. A 50% reduction of light intensity by shading of single branches reduced isoprene synthase activity by ≈ 60% compared with full sunlight. The calculation of isoprene synthesis capacities based on enzymatic data obtained under optimum reaction conditions, corrected for actual leaf temperature and related to leaf surface area, provides a sound basis for predicting the isoprene emission potential of plants.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The emission rate of the volatile reactive compound isoprene, emitted predominantly by trees, must be known before the level of photo-oxidants produced during summer smog can be predicted reliably. The emission is dependent on plant species and local conditions, and these dependencies must be quantified to be included in any empirical algorithm for the calculation of isoprene production. Experimental measurements of isoprene emission rates are expensive, however, and existing data are scarce and fragmentary. To overcome these difficulties, it is promising to develop a numerical model capable of precisely calculating the isoprene emission by trees for diverse ecosystems, even under changing environmental conditions. A basic process-based biochemical isoprene emission model (BIM) has therefore been developed, which describes the enzymatic reactions in leaf chloroplasts leading to the formation of isoprene under varying environmental conditions (e.g. light intensity, temperature). Concentrations of the precursors of isoprene formation, 3-phosphoglyceric acid and glyceraldehyde 3-phosphate, are provided by a published light fleck photosynthesis model. Specific leaf and enzyme parameters were determined for the pedunculate oak (Quercus robur L.), so that the BIM is capable of calculating oak-specific isoprene emission rates as influenced by the leaf temperature and light intensity. High correlation was observed between isoprene emission rates calculated by the BIM and the diurnal isoprene emission rates of leaves measured under controlled environmental conditions. The BIM was even capable of describing changes in isoprene emission caused by midday depression of net photosynthesis.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...