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  • Spektralphotometrie  (58)
  • Synapses  (37)
  • Springer  (95)
  • American Physical Society
  • MDPI Publishing
  • Nature Publishing Group
  • 1970-1974  (95)
  • 1950-1954
Collection
Keywords
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  • Springer  (95)
  • American Physical Society
  • MDPI Publishing
  • Nature Publishing Group
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    The locus coeruleus of cat (1974)
    Springer
    Cell & tissue research 149 (1974), S. 205-221 
    Details
    ISSN: 1432-0878
    Keywords: Locus coeruleus ; Tegmentum ; Mesencephalon ; Adrenergic centers ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The locus coeruleus of cat is populated by two types of neurons: medium sized ones, with plump cell bodies and relatively short dendrites; and small ones, with triangular bodies and relatively long dendrites. The former type is regarded here as typical of the centre, whereas the second type could simply represent displaced neurons from the adjacent griseum centrale. Electron microscopy failed to reveal any outstanding richness in pigment granules in kittens up to five weeks old. Very characteristic somatic appendages were found, mostly in the medium sized neurons. These somatic “spines” communicate with the perikaryon by means of a narrow neck region. A complex, multilayered, glial sheath surrounds the cells. This glial sheath is pierced by the somatic appendages, which are not surrounded by glia and make contact with axonal knobs. Typical dendritic spines appear to be absent. Axodendritic synapses are made on medium sized dendritic trunks. By and large, most of the synaptic vesicles present in the centre are of the small, clear-centered type. However, dense core vesicles extremely variegated in size and appearance were found, both in presynaptic and postsynaptic profiles. The possibility that dense core vesicles should be regarded as atypical lysosomes rich in by-products of the metabolism of catecholamines (melanine) has been considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222274
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  • 2
    Electronic Resource
    Electronic Resource
    The ultrastructure of lateral line sense organs in the juvenile salamander Ambystoma mexicanum (1974)
    Springer
    Cell & tissue research 152 (1974), S. 283-292 
    Details
    ISSN: 1432-0878
    Keywords: Sense organ ; Lateral line ; Synapses ; Ambystoma mexicanum ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Lateral line organs in young salamanders of the species Ambystoma mexicanum were investigated with scanning and transmission electron microscopy. They were found to differ from the lateral line organs in adult animals (1) by being lower, having short hair cells and supporting cells, (2) by the hair cells having areas of lateral contact, (3) by the occasional presence, at the edge of the organ, of hair cells at an early developmental stage. Two types of nerve endings are seen: (1) afferent, and (2) less commonly, efferent vesiculated ones. Synaptic bodies have been seen in the cytoplasm without association to afferent synapses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223950
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  • 3
    Electronic Resource
    Electronic Resource
    The distribution of synapses along the spinal cord of an amphibian embryo: An electron microscope study of junction development (1974)
    Springer
    Cell & tissue research 153 (1974), S. 227-244 
    Details
    ISSN: 1432-0878
    Keywords: Synapses ; Embryo (Xenopus laevis) ; Spinal cord ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The rostro-caudal gradient of differentiation found in vertebrate embryos has been utilized to examine the sequence of synaptic junction development in the spinal cord of Xenopus laevis at a late embryonic stage. Uniform samples were taken at various points along the cord of a stage 27 embryo and examined in the electron microscope. The general ultrastructure of the cord demonstrated the rostro-caudal gradient of development. The sequence of synaptic junction development was like that in the cervical region (Hayes and Roberts, 1973). “Membrane-vesicle clusters” and “immature” synaptic junctions were found most caudally followed by synaptic junctions, first with cleft and subsynaptic membrane density, then with only cleft density and finally, most rostrally, with cleft, subsynaptic membrane, and subsynaptic cytoplasmic density. Mature synaptic junctions were found in increasing numbers from the mid to anterior trunk cord and could mediate alternating trunk flexions made by the embryos at this stage of development. “Membrane-vesicle clusters” were found near processes containing irregular vesicles and also near membrane outlines. These may be signs of dendritic growth. “Membrane-vesicle clusters” were also found in varicosities, facing the space around the spinal cord and in nerve fibres peripherally between the skin and myotomes. This suggests an association of early stages in synaptogenesis with axon growth. This and other possible inferences about axon and dendrite growth in relation to synaptogenesis are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226611
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  • 4
    Electronic Resource
    Electronic Resource
    Spektralphotometrische Bestimmung von Val5-Angiotensin II Asp1-β-amid durch Azokupplung mit p-Chlorbenzoldiazoniumchlorid (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 269 (1974), S. 187-192 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Val5-Angiotensin II Asp1-β-amid, Hypertensin, Peptidhormone ; Spektralphotometrie ; Azokupplung mit Halogenbenzoldiazoniumsalz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Am Beispiel des Octapeptids Val5-Angiotensin II Asp1-β-amid (Hypertensin-CIBA) wird die Möglichkeit aufgezeigt, Polypeptidhormone mit Tyrosin und/oder Histidin im Molekül über eine Kupplung mit p-halogensubstituierten Benzol-diazoniumsalzen quantitativ zu erfassen. Durch photometrische Bestimmung des Kupplungsprodukts konnten noch 1–2 nMol Hypertensin nachgewiesen werden. Eine Steigerung der Empfindlichkeit läßt sich durch Kupplung des Polypeptids mit radioaktiv markierten Diazoniumsalzen erreichen. Die als besonders günstig ermittelten Bedingungen für die Diazotierungs- und Kupplungsreaktionen werden mitgeteilt. Das Kupplungsprodukt war papier-chromatographisch einheitlich. Es handelt sich vermutlich um eine Monoazoverbindung. Unter den gewählten Bedingungen stellt sehr wahrscheinlich Tyrosin den kupplungsfähigen Aminosäurerest im Hypertensinmolekül dar.
    Notes: Abstract Through the azocoupling of Val5-angiotensin II-Asp1-β-amide (Hypertensin-CIBA) with p-halogene substituted benzenediazonium salts the possibility is shown for quantitative determination of polypeptides containing tyrosine and/or histidine. 1 to 2 nanomoles of the coupling-product could be measured photometrically. The detection limit can be lowered, if the polypeptide is coupled with a radioactive labelled diazonium salt. The preferable reaction conditions for diazotising and coupling are reported. The reaction-product showed an uniform behaviour in the used paper-chromatographic system. Probably it is a monoazo compound. Under the chosen conditions the tyrosyl group is very likely the reacting part of the hypertensin molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00424312
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  • 5
    Electronic Resource
    Electronic Resource
    Spektralphotometrische Bestimmung von p-Phenetidin, p-Aminophenol und p-Amino-phenoxy-essigsäure nach quantitativer Trennung aus wäßriger Lösung (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 268 (1974), S. 367-368 
    Details
    ISSN: 1618-2650
    Keywords: Best. von p-Phenetidin, p-Aminophenol, p-Amino-phenoxy-essigsäure ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01155029
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  • 6
    Electronic Resource
    Electronic Resource
    Photometrische Sulfitbestimmung mit Trinitrobenzoesäure (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 269 (1974), S. 15-18 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Sulfit mit Trinitrobenzoesäure ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung SO3 2− kann mit Trinitrobenzoesäure innerhalb von 2 min photometrisch bestimmt werden. SO4 2−, S2O3 2−, S2− und SxO6 2− in Konzentrationen bis zu 1 mMol/100 ml stören nicht. Die untere Bestimmungsgrenze beträgt 0,22mg SO3 2−/100 ml, die Standardabweichung bei der Bestimmung von 7 mg SO3 2− ± 0,59 Rel.-%.
    Notes: Abstract SO3 2− can be determined photometrically with trinitrobenzoic acid within 2 min. SO4 2−, S2O3 2−, S2− and SxO6 2− in concentrations up to 1 mMole/100 ml do not interfere. The limit of determination is 0.22 mg SO3 2−/100 ml, the standard deviation for the determination of 7 mg SO3 2− is ± 0.59 Rel.-%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00423932
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  • 7
    Electronic Resource
    Electronic Resource
    Spektralphotometrische Bestimmung von Hydroxypropylgruppen in Cellulose-Mischäthern mit Ninhydrin (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 271 (1974), S. 31-31 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Hydroxypropylgruppen in Cellulose-Mischäther ; Spektralphotometrie ; Ninhydrin als Reagens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00437488
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  • 8
    Electronic Resource
    Electronic Resource
    Spectrophotometric determination of amylose by double wavelength method (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 271 (1974), S. 208-208 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Amylose ; Spektralphotometrie ; zwei Wellenlängen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430736
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  • 9
    Electronic Resource
    Electronic Resource
    Direct spectrophotometric determination of aluminium with SPADNS (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 271 (1974), S. 284-284 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Aluminium ; Spektralphotometrie ; SPADNS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432832
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  • 10
    Electronic Resource
    Electronic Resource
    Spectrophotometric determination of copper, nickel and cobalt after extraction with benzoyltrifluoroacetone (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 271 (1974), S. 286-286 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Kupfer, Nickel, Kobalt mit Benzoyltrifluoraceton ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432835
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  • 11
    Electronic Resource
    Electronic Resource
    Hochselektive spektralphotometrische Bestimmung von Nitrat mit β-Methylumbelliferon (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 271 (1974), S. 359-361 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Nitrat mitβ-Methylumbelliferon ; Spektralphotometrie ; hochselektive Modifikation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Anwendbarkeit der spektralphotometrischen Nitratbestimmung mitβ-Methylumbelliferon wurde durch folgende Maßnahmen wesentlich erweitert: Abtrennung auftretender Niederschläge mit einem Membranfilter aus Cellulosenitrat, Fällung bzw. Maskierung störender Anionen mit AgClO4 und Reduktion störender Kationen mit Na2SO3. Der Einfluß von mehr als 60 Kationen und 20 Anionen auf die NO3 −-Bestimmung wird angegeben.
    Notes: Abstract The applicability of the spectrophotometric nitrate determination by utilizingβ-methylumbelliferone has been extended by the following measures: Separation of eventual precipitates by means of a membrane filter consisting of cellulose nitrate, separating or masking of interfering anions with AgClO4 and reduction of interfering cations by the use of Na2SO3. The influence of more than 60 cations and 20 anions on the determination of nitrate is listed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00820741
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  • 12
    Electronic Resource
    Electronic Resource
    A new possibility for the spectrophotometric determination of steroid sulphates (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 272 (1974), S. 37-39 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Steroidsulfaten ; Spektralphotometrie ; Cu-Pyridin-Komplex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A new procedure has been developed for the quantitative determination of steroid sulphates. The basic principle of the method is that a pyridine solution of the pyridinium salt of the steroid sulphate is shaken at room temperature with metallic copper powder or copper(I)-oxide, and the intensity of the coloured complex formed is measured at 310–350 nm. The method is suitable both for the total steroid sulphate determination of various extracts, and for the quantitative determination of steroid sulphates previously separated by some other method. Errors are in the range of 0.5–2%.
    Notes: Zusammenfassung Eine Lösung des Pyridiniumsalzes des Steroidsulfats in Pyridin wird bei Raumtemperatur mit metallischem Kupferpulver oder Kupfer(I)-oxid geschüttelt und die Absorption des gebildeten Farbkomplexes bei 310–350 nm gemessen. Das Verfahren eignet sich zur Bestimmung des Gesamtgehaltes an Steroidsulfat in verschiedenartigen Extrakten sowie zur Bestimmung von zuvor abgetrenntem Steroidsulfat. Die Fehler liegen im Bereich von 0,5–2%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430527
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  • 13
    Electronic Resource
    Electronic Resource
    Spectrophotometric determination of silver(I) with 4-(2-pyridylazo)-resorcinol (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 272 (1974), S. 44-44 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Silber mit 4-(2-Pyridylazo)-resorcin ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430531
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  • 14
    Electronic Resource
    Electronic Resource
    Spectrophotometric determination of traces of cobalt with 1-naphthamidoxime (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 272 (1974), S. 48-48 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Kobalt mit 1-Naphthamidoxim ; Spektralphotometrie ; Spuren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430535
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  • 15
    Electronic Resource
    Electronic Resource
    Extraction spectrophotometric determination of iron(II) with Thiodibenzoylmethane (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 272 (1974), S. 283-283 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Eisen(II) mit Thiodibenzoylmethan ; Spektralphotometrie ; Extraktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431342
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  • 16
    Electronic Resource
    Electronic Resource
    Bestimmung des freien Glykolaldehydgehaltes in Äthylenglykol (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 272 (1974), S. 284-285 
    Details
    ISSN: 1618-2650
    Keywords: Bestimmung von Glykolaldehyd in Äthylenglykol ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431344
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  • 17
    Electronic Resource
    Electronic Resource
    Note on the spectrophotometric determination of cerium(IV) with crystal violet (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 272 (1974), S. 364-364 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Cer(IV) mit Kristallviolett ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00424024
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  • 18
    Electronic Resource
    Electronic Resource
    Spectrophotometric microdetermination of palladium with chromotrope 2R (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 272 (1974), S. 366-366 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Palladium mit Chromotrop 2R ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00424027
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  • 19
    Electronic Resource
    Electronic Resource
    Acenaphthenequinonemonoxime as a spectrophotometric reagent for the determination of iridium by solvent extraction (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 268 (1974), S. 31-32 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Iridium mit Acenaphthenchinonmonoxim ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430905
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  • 20
    Electronic Resource
    Electronic Resource
    On the use of spectrophotometric methods for the determination of the composition of metal complexes (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 269 (1974), S. 97-99 
    Details
    ISSN: 1618-2650
    Keywords: Best. der Zusammensetzung von Metallkomplexen ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary If the method of continuous variations as well as methods like the molar-ratio method are applied to complex formation reactions that take place stepwise, plots can be obtained in which the existence of intermediate complexes is fully obscured. An illustration is given for the complex formation between Cu2+ and pyridine-2,6-dicarboxylic acid.
    Notes: Zusammenfassung Über den Gebrauch spektralphotometrischer Methoden zur Bestimmung der Zusammensetzung von Metallkomplexen. Wenn die Methode der kontinuierlichen Variationen und Verfahren wie die Molar-ratio-Methode für den Fall stufenweiser Komplexbildung angewendet werden, können graphische Darstellungen erhalten werden, in denen die Existenz von intermediären Komplexen völlig verdeckt ist. Dies wird für die Komplexbildung zwischen Kupfer(II) und Pyridin-2,6-dicarbonsäure gezeigt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00424680
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  • 21
    Electronic Resource
    Electronic Resource
    Über eine neue photometrische Aminosäurebestimmung mit p-Benzochinon in biologischen Flüssigkeiten (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 269 (1974), S. 182-187 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Aminosäuren mit p-Benzochinon ; Spektralphotometrie ; Charge-Transfer-Komplexe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Aminosäuren können in Gegenwart organischer Lösungsmittel als Elektronen-Donator-Acceptor-Komplexe mit p-Benzochinon bestimmt werden. Die Methode vereinigt stabile Farbreaktion, hohe Empfindlichkeit (ɛ 490=2,5 cm2/μMol α-Aminosäure, 4,4 cm2/μMol α,ɛ-Aminosäure und ɛ 525=4,65 cm2/μMol Prolin), rasche, einfache und billige Durchführung mit guter Reproduzierbarkeit, ausreichender Spezifität und Unempfindlichkeit gegenüber Ammoniak und anorganischen Verbindungen. Es werden optimale Bedingungen für die Bestimmung von Aminostickstoff im Serum und Urin und Normalwerte bei Gesunden beschrieben.
    Notes: Abstract Amino acids can be determined as charge-transfer complexes by reaction with p-benzoquinone in the presence of organic solvents. This method combines high sensitivity (ɛ 490=2.5 cm2/μmole α-amino acid and 4.4 cm2 /μmole α,ɛ-amino acid; ɛ 525=4.65 cm2/μmole proline) and rapid, cheap and simple procedure with good reproducibility, sufficient specifity, stable colour and insensitivity to ammonia and inorganic compounds. Optimal conditions and normal values are reported for the determination of amino nitrogen in serum and urine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00424311
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  • 22
    Electronic Resource
    Electronic Resource
    Spectrophotometric determination of trace amounts of iron(II) using 7-nitroso-8-hydroxyquinoline-5-sulphonic acid as reagent (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 270 (1974), S. 32-32 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Eisen(II) mit 7-Nitroso-8-hydroxychinolin-5-sulfonsäure ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00595883
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  • 23
    Electronic Resource
    Electronic Resource
    Determination of empirical parameters of solvent polarity E T in binary mixtures by solvatochromic pyridinium-N-phenol betaine dyes (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 270 (1974), S. 100-104 
    Details
    ISSN: 1618-2650
    Keywords: Analyse von binären Lösungsmittelgemischen ; Spektralphotometrie ; Solvatochrome Farbstoffe, synergistische Polaritätseffekte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Empirical parameters of solvent polarity E T of some pure solvents and their binary mixtures (especially with CCl4 and CHCl3) were determined spectrophotometrically using solvatochromic pyridinium-N-phendl betaine dyes. Calibration curves are given for 16 binary solvent mixtures. The obtained E T values show that a synergetic polarity effect appears with the organic solvents containing C=O, P=O, and S=O groups in the mixture with chloroform. With these binary mixtures the increase of E T values results from the formation of 1∶1 complexes X=O... H-CCl3 by means of hydrogen bonding. Increasing number of methylene groups in the chain increases the synergism with these type of complexes.
    Notes: Zusammenfassung Empirische Parameter der Lösungsmittelpolarität E T einiger reiner Lösungsmittel und ihrer binären Mischungen (insbesondere mit CCl4 und CHCl3) wurden mit Hilfe von solvatochromen Pyridinium-N-phenolbetain-Farbstoffen bestimmt. Für 16 binäre Lösungsmittelgemische wurden Eichkurven ermittelt. Die erhaltenen E T -Werte zeigen, daß organische Lösungsmittel mit C=O-, P=O- und S=O-Gruppen in Mischungen mit Chloroform einen synergistischen Polaritätseffekt aufweisen. Die Zunahme der E T -Werte in diesen binären Mischungen beruht auf der Bildung von durch Wasserstoff brücken gebundenen 1∶1-Komplexen X=O... H-CCl3. Die Verlängerung der Alkylkette führt zu einer Zunahme des Synergismus bei dieser Art von Komplexen.
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    URL: http://dx.doi.org/10.1007/BF00434059
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  • 24
    Electronic Resource
    Electronic Resource
    Determination of chromium(III) with EDTA at the ppm-level by difference spectrophotometry in the UV-region (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 270 (1974), S. 206-207 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Chrom(III) mit ÄDTA ; Spektralphotometrie ; Differenzmethode im UV-Bereich
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00445961
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    Bestimmung organisch gebundenen Fluors in biologischem Material (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 270 (1974), S. 278-282 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Fluor in Biolog. Material ; Spektralphotometrie ; Applikation von Flufenaminsäure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Nach Extraktion aller F-haltigen Substanzen (intakte Substanz plus Summe aller Metaboliten) aus Urin (alkalisch in der Wärme hydrolysiert) von Menschen und Tieren, welche Flufenaminsäure bzw. deren Derivate appliziert bekamen, können Untersuchungen der Ausscheidungsbilanz durchgeführt werden. Nach alkalisch oxidativem Abbau (Wurzschmittsche Bombe) wurde aus schwefelsauren Ansätzen mit SiO2 destilliert und die Ansätze mit Alizarin-3-methylamin-N,N-diessigsäure-Cer(III)-Komplex bei pH 4,35 colorimetrisch untersucht. Messungen im Konzentrationsbereich ≤1 μg pro Meßansatz sind möglich. Die Ergebnisse der renalen Elimination von Flufenaminsäure und Metaboliten beim Menschen (49,4±4,6%; N=10) stimmen größenordnungsmäßig mit den Befunden anderer Autoren, welche Tracer-Methoden angewendet hatten (51%; N=4), gut überein und beweisen damit die Brauchbarkeit der Methode.
    Notes: Abstract After extraction of all F-containing substances (intact substance and the sum of all metabolites) from urine (hydrolysed in alkali under heating) of both man and animals after administration of flufenamic acid and derivatives, the balance of excretion can be determined. After alkaline oxydative degradation (Wurzschmitt bomb) of these extracts and distillation in the presence of sulphuric acid and SiO2 the distillates were investigated colorimetrically at pH 4.35 after addition of an alizarine-3-methylamino-N,N-diacetic-cerium(III) complex. Measurements in the range of ≤1 μg per sample used are possible. The results obtained for the renal elimination of flufenamic acid and metabolites in man (49.4±4.6%; N=10) are in concordance with the results of other authors who used tracer methods (51%; N=4) and prove the practicability of this method.
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    Application of orthogonal functions to the determination of dihydrocodeine in presence of noscapine (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 270 (1974), S. 282-285 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Dihydrocodein neben Noscapin ; Spektralphotometrie ; Anwendung von Orthogonalfunktionen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die direkte photometrische Bestimmung von Dihydrocodeinbitartrat (5 mg) neben der Hauptkomponente Noscapin (Narcotin)-hydrochlorid (25 mg) ohne Abtrennung gelingt, wenn zur Auswertung Orthogonalpolynome herangezogen werden. Eine andere Methode basiert auf der Fällung der Noscapinbase mit gesättigter Natriumacetatlösung. Auch in diesem Fall wird das Dihydrocodein über Orthogonalfunktionen bestimmt, um den Restanteil von Noscapin zu eliminieren und eventuell störende unspezifische Untergrundabsorptionen auszuschließen. Die Standardabweichung beträgt 1,56 ohne Abtrennung und 0,66 bei Fällung des Noscapins.
    Notes: Summary The orthogonal function method is applied to the determination of dihydrocodeine bitartrate as a minor component (5 mg) in presence of noscapine hydrochloride (25 mg) without separation. Another method based upon precipitating noscapine by a saturated solution of sodium acetate is also presented. Dihydrocodeine is determined in the filtrate using the orthogonal function method to correct for the unprecipitated fraction of noscapine. Standard deviation is 1.56 and 0.66 for direct and precipitation methods, respectively.
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    URL: http://dx.doi.org/10.1007/BF00431327
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    The granule-containing cell somata in the superior cervical ganglion of the rat, as studied by a serial sampling method for electron microscopy (1973)
    Springer
    Cell & tissue research 141 (1973), S. 331-345 
    Details
    ISSN: 1432-0878
    Keywords: Sympathetic ganglion ; Granule-containing cells ; Synapses ; Three-dimensional analysis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The surface of 4 granule-containing cells, in a cluster within the rat superior cervical ganglion, was studied by a serial sampling technique for electron microscopy. The result shows that all the 4 cells receive one, or three afferent synaptic boutons from the preganglionic fibers impinging upon their somata, and a somatic efferent synapse exists at two locations on each soma of the 2 of these cells. The postsynaptic element of the efferent synapse is observed to be represented by non-vesiculated and vesiculated segments of dendrites, soma and a possible axon collateral of the adrenergic principal neuron of the ganglion. There is a remarkably constant development of the attachment plaque between the granule-containing cells themselves, representing 1.7–2.3% of surface area for each cell. The surface area exposed to the extracellular space (covered only by a basal lamina) varies from 0.1 to 2.3% of the total perikaryal surface of the 4 cells. A tendency is noted that those cells without efferent synapses possess a more extensive area exposed to extracellular space than those forming somatic efferent synapse to the postganglionic elements.
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    Le système nerveux des cténaires (1973)
    Springer
    Cell & tissue research 143 (1973), S. 117-133 
    Details
    ISSN: 1432-0878
    Keywords: Nervous system ; Ctenophores ; Intra-mesogleal nervous system ; Synapses ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural evidence is given of the occurrence of nervous elements in the mesoglea of Ctenophores based on the presence of the typical synapses of this phylum. In Beroids, nervous fibers from the ectodermal nerve-net cross the epithelial basal membrane and run through the mesoglea; they are devoid of any ensheathing cell. These neurites build highly differentiated synapses upon the muscles and upon peculiar cells, tentatively named mesenchymal cells. In Cydippids, nerve fibers and nerve cell-bodies have been observed in the mesoglea of the tentacles. The mesogleal core of each tentacle contains mesenchymal cells and a thick strand of neurons and neurites, forming a kind of elongated ganglion. Neurites of either the axial neurones or the epithelial nerve-net neurones form numerous radial nerve strands across the tentacular muscles. Interneural, neuro-muscular and neuro-mesenchymal junctions are very frequent in the tentacle. As far as the organization of the mesoglea is concerned, the Ctenophora thus appear closer to Turbellaria than to Cnidaria.
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    URL: http://dx.doi.org/10.1007/BF00307455
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    Zur Feinstruktur des dorsalen Riesenfasersystems im Bauchmark des Regenwurms (1973)
    Springer
    Cell & tissue research 139 (1973), S. 369-396 
    Details
    ISSN: 1432-0878
    Keywords: Synapses ; Giant fibres ; Ventral nerve cord ; Lumbricus terrestris L. ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die proximalen Kollateralen der dorsalen Riesenfasern des Regenwurms wurden in Serienschnitten vom Soma bis zum Eintritt in die Riesenfaser verfolgt und im Hinblick auf ihre Feinstruktur und ihre synaptischen Kontakte Untersucht. Es finden sich sowohl chemische als auch elektrische Synapsen. Ihre Feinstruktur wird mit der bekannter Synapsen anderer Wirbellosen und Wirbeltiere verglichen. In beiden Riesenfasersystemen kommen efferente chemische Synapsen mit feinen postsynaptischen Verzweigungen vor, die anscheinend von Bauchmark-Motoneuronen stammen. Das Axon der medianen Riesenfaser weist darüber hinaus nur noch eine elektrische Synapse mit den Rieseninterneuronen auf. Demgegenüber erhalten die Kollateralen der lateralen Riesenfasern zahlreiche Afferenzen, die zum Teil als sensorische Fasern der Epidermis, multisegmentale Fasern der Hauptfaserzüge und Rieseninterneurone identifiziert werden konnten. Weitere Afferenzen stammen vermutlich von unisegmentalen Interneuronen her. Beide lateralen Riesenzellaxone bilden außerdem miteinander eine elektrische Chiasma-Synapse mit besonderen Membraneinfaltungen.
    Notes: Summary The proximal collaterals of the dorsal giant fibres of the earthworm were traced through serial sections from the cell bodies to the giant axons. Their structure and synaptic connections were examined. There are chemical as well as electrical synapses. Their fine structure is compared to that of other known invertebrate and vertebrate synapses. Both giant fibre systems have efferent chemical connections with thin postsynaptic arborizations which probably belong to ventral cord motoneurons. Moreover the median giant axon is connected by an electrical synapse with the giant interneurons. The lateral giant collaterals on the contrary receive many afferences through chemical synapses which were partly identified as sensory fibers from the epidermis, multisegmental axons from the main fibre bundles or giant interneurones. Other afferences probably come from unisegmental interneurones. In addition both lateral giant axons form an electrical chiasma synapse with special membrane folds.
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    A light and electron microscope study of the nervous system of Ceriantheopsis americanus (cnidaria, ceriantharia) (1973)
    Springer
    Cell & tissue research 141 (1973), S. 301-317 
    Details
    ISSN: 1432-0878
    Keywords: Cnidaria ; Nervous system ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The nervous system of juvenile and adult Ceriantheopsis americanus has been examined with the electron microscope. The nervous system is exclusively ectodermal, forming a plexus of fibres lying between the epithelium and the muscle layer. The plexus consists of three types of nerve fibre that vary in diameter from 0.1 to 20 μ, and a fourth type of fibre of uncertain nature. The reticulum, previously thought to be the ectodermal nervous system, is redescribed as the peduncles of epithelial supporting cells. Intraneural and neuromuscular synapses are described. About 97% of the interneural are polarized. The unpolarized synapses are a variety not previously described, consisting of a series of polarized zones, for which the name multipolarized synapse is proposed. Structurally, the interneural synapses are more complex than those previously seen in the Cnidaria. Presynaptic projections, periodic cleft densities, and a postsynaptic web are described. By contrast, the neuromuscular synapses bear no membrane specializations. On the basis of observed synaptic interactions of its components a preliminary model of the functional organization of the nervous system is proposed.
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    URL: http://dx.doi.org/10.1007/BF00307408
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    Le Système Nerveux des Cténaires (1973)
    Springer
    Cell & tissue research 137 (1973), S. 223-250 
    Details
    ISSN: 1432-0878
    Keywords: Nervous system ; Ctenophores ; Nerve-net, Nervous concentration ; Synapses ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A subectodermal nerve-net is demonstrated in ten species of Ctenophores by means of either Methylene Blue vital staining or silver impregnation. There is no evidence of subendodermal nerve-net. The ectodermal nerve-net displays a characteristic polygonal pattern which is thought to result from morphogenetic events. Both bipolar and tripolar neurones occur. Three types of concentrations of nervous tissue are described: a) a high accumulation of nervous perikarya at the aboral sensory pole; b) a noticeable densification of the net along the eight meridional ciliary strands of every species, and around the lips of Beroidea; c) in the Cydippids Pleurobrachia and Hormiphora two thick strands of fibers and neurones interconnecting the aboral organ and the tentacles: the tentacular nerves. Ultrastructural evidence is given for the presence of nervous elements under and amidst ectodermal epithelial cells. Three features allow the recognition and characterization of neurites and neurones: a) numerous clear and/or granulated vesicles; b) microtubules in variable amounts; c) frequent and highly differentiated synaptic contacts. The very peculiar arrangement of the presynaptic elements is observed in all the species of Ctenophores so far studied. These synaptic contacts suggest chemical transmission in the nerve-net. On the basis of ultrastructural evidence the author refutes the nervous nature previously attributed to the ciliated cells of the meridional grooves. A parallel is drawn between nervous systems of Cnidaria and Ctenophora.
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    Fluorescence and electron microscopy of the monoamine-containing cells in the turtle heart (1973)
    Springer
    Cell & tissue research 140 (1973), S. 25-37 
    Details
    ISSN: 1432-0878
    Keywords: Heart innervation (Turtle) ; Monomamine-containing cells ; Synapses ; Fluorescence and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fluorescence and electron microscopy of the turtle heart indicates the presence of monoamine-containing, granulated cells in the wall of venous sinus and near the openings of the aortic trunks. These cells occur in clusters and are always in association with nerve fibers and/or ganglion cells within the turtle heart. Vesiculated axon terminals make a synaptic contact with the cytolemma of the granulated cell which in turn makes a synapse to the processes from the other granulated cell and to the cardiac nerve fibers. The close contact occurs also between the granulated cell process and the smooth muscle cell membrane in the wall of large vessels. The granulated cell has no special relationship to the blood capillaries. The significance of these results is discussed in relation to nervous control of the cardiac activity of the turtle.
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    The development of synapses in vitro between previously dissociated chick spinal cord neurons (1973)
    Springer
    Cell & tissue research 140 (1973), S. 203-216 
    Details
    ISSN: 1432-0878
    Keywords: Synapses ; Development ; Chick embryo ; Cell culture ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The formation and development of synaptic contacts between dissociated chick spinal cord neurons has been investigated. By the 6th day in vitro “immature” profiles with few vesicles were observed. By 14–18 days “mature” types with numerous vesicles were found, indistinguishable from those of newly hatched chick spinal cord. After this period degeneration occurred, and was especially marked in the post-synaptic element. Such degeneration could be postponed by the addition of small numbers of somatic muscle cells. The Kanaseki and Kadota (1969) technique was applied to the study of coated vesicles at various stages of synaptic development.
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    Verbesserte Methode zur Bestimmung von CO-Spuren in Wasserstoff (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 263 (1973), S. 331-333 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Kohlenmonoxid in Wasserstoff ; Spektralphotometrie ; Ag-Na-Sulfamidbenzoat als Reagens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00426126
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    Spectrophotometric determination of tin in zircaloy with phenylfluorone (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 263 (1973), S. 334-334 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Zinn in Zircaloy ; Spektralphotometrie ; Phenylfluoron als Reagens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00426128
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    Über Dithizonate von Organo-Gallium-Verbindungen (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 264 (1973), S. 131-133 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Gallium-Organoverbindungen ; Spektralphotometrie ; Extraktion der Dithizonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Reaktionsfähigkeit von Organo-Gallium-Verbindungen mit Dithizon wurde festgestellt. Die Dithizonate der alky- loder arylgruppentragenden Pseudoionen RGa2+ und R2Ga+ sind mit violettstichig roter Farbe in Tetra oder Chloroform extrahierbar. Über die Bildung der diesbezüglichen Dithizonate sowie deren charakteristische Eigenschaften werden nähere Angaben gemacht. Die analytische Bestimmung des R2Ga+ ist nach dem photometrischen Mischfarbenverfahren möglich.
    Notes: Abstract The reactivity of organo-gallium compounds has been established. The dithizonates of the pseudoions RGa2+ and R2Ga+ are in connection with alkyl or aryl groups extractable with red colour with a tinge of violet into carbon tetrachloride or chloroform. Detailed information on the formation of these dithizonates and their characteristic properties is given. The analytical determination of R2Ga+ is possible with the mixed-colour method.
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    Some studies of the colorimetric determination of tin in steel: The effect of dispersing agents (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 264 (1973), S. 133-138 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Zinn in Stahl ; Spektralphotometrie ; Brenzcatechinviolett, Phenylfluoron ; Dispergierungsmittel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A survey of existing procedures for the colorimetric determination of tin in steel is given. Recommendations are made with regard to separating tin, masking interfering metals and selecting a colorimetric finish. The effect of dispersing agents on reagents of the type used for determining tin, and on the complexes formed in these determinations, is discussed, including new work on the effect of cetyltrimethylammonium bromide on the phenylfluorone-tin(IV) system.
    Notes: Zusammenfassung Ein Überblick über colorimetrische Zinnbestimmungsmethoden in Stahl wird gegeben und Vorschläge zur Abtrennung des Zinns, der Maskierung störender Metalle sowie der Auswahl des colorimetrischen Meßverfahrens gemacht. Der Einfluß von Dispergierungsmitteln auf die Eeagentien und gebildeten Komplexe wird diskutiert, wobei über neue Untersuchungen zum Einfluß von Cetyltrimethylammoniumbromid auf das System Phenylfluoron/Zinn(IV) berichtet wird.
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    Beitrag zur Bestimmung von Phenylquecksilberborat in Augentropfen mittels flammenloser Atom-Absorptionsspektrometrie (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 264 (1973), S. 412-413 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Phenylquecksilberborat in Augentropfen, Pharmazeut. Produkten ; Spektralphotometrie ; Atomabsorption ; flammenlos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00423647
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    Photometrische Bestimmung von Antimon in Eisen und Stahl (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 265 (1973), S. 29-30 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Antimon in Eisen und Stahl ; Spektralphotometrie ; Methylfluoron als Reagens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Zur Bestimmung von 2,5–100 ppm Sb in Eisen, unlegierten und niedrig legierten Stählen sowie in Automatenstählen wird das Antimon zuerst in 2 Stufen vorisoliert mit Hilfe der Spurenfällung mit Mangan(IV)-oxidhydrat als Spurenfänger und anschließender Jodidextraktion. Nach der Rückextraktion erfolgt die photometrische Bestimmung mit Methylfluoron in der wäßrigen Phase. Der relative Fehler beträgt ±5%, der Zeitbedarf für eine Einzelbestimmung 1,5 h.
    Notes: Abstract For the determination of 2.5–100 ppm Sb in iron, plain carbon steels, low-alloy and free-cutting steels antimony is at first separated in two steps. It is coprecipitated with manganese(IV)oxide hydrate as collector, the precipitate dissolved and antimony extracted as iodide with benzene. After back extraction antimony is determined photometrically in the aqueous phase with methylfluorone. The relative error is ± 5%. One determination requires 1.5 h.
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    Sensibilisierung eines Zweizellenphotocolorimeters zur Verbesserung der Spurenanalyse (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 265 (1973), S. 104-113 
    Details
    ISSN: 1618-2650
    Keywords: Spektralphotometrie ; Spurenanalyse ; Sensibilisierung eines Zweizellen-Photocolorimeters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine spektralphotometrische Methode wird beschrieben, die es ermöglicht, Elemente in kleinen Konzentrationen zu bestimmen. Dies wird im Prinzip durch den Anschluß eines hochempfindlichen Galvanometers an ein Zweizellenphotocolorimeter ermöglicht. Der so erreichte Gewinn an Empfindlichkeit wird einesteils durch die Anwendung von zwei Interferenzfiltern dazu genutzt, die Selektivität des Systems zu erhöhen, anderenteils kann mit dem Ersatz der Lichtschutzklappe durch Küvetten mit sog. Limitlösungen (Lösungen bekannter, entsprechender Konzentration) das System auf den optimalen Meßbereich ausgewogen werden. Zu den Hauptvorteilen dieser Methode zählen: Senkung der Nachweisgrenze (z.B. bei Mn von 20,27 auf 0,18 μg), variable Wahl der optimalen Empfindlichkeit, optimales Auflösungsvermögen durch die Möglichkeit der Skalendehnung im gewünschten Konzentrationsintervall, Erhöhung der Genauigkeit sowie leichte Konstruktion der diagonal zum Koordinatenkreuz unter einem Winkel von 45° verlaufenden Eichkurve.
    Notes: Abstract A spectrophotometric method is described by which it is possible to determine elements in low concentrations. This is achieved by the connection of a highly sensitive galvanometer to a two-cell photocolorimeter. The higher precision attained in this way can be used on the one hand by the application of two interference filters for the increase of the selectivity of the system, on the other hand, with the replacement of the flap by measurement cells with so-called limit solutions (solutions of known, corresponding concentration) for balancing the system for an optimum range of measurement. The main advantages of this method are: decrease of the limit of detection (e.g. of Mn from 20.27 to 0.18 μg), choice of an optimum sensitivity, an optimum separating power by the possibility of extending the scale in the necessary concentration interval, increase of precision and an easy construction of the calibration curve, located diagonally under a 45° angle to the coordinate system.
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    Über das 2,3,7-Trihydroxy-9-(2-chinolyl)-isoxanthenon-(6) (2′-Chinolylfluoron) und seine Verwendung zur photometrischen Bestimmung von Zirkonium (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 265 (1973), S. 260-266 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Zirkonium mit 2,3,7-Trihydroxy-9-(2-chinolyl)-isoxanthenon-(6), 2′-Chinolylfluoron ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Darstellung des 2′-Chinolylfluorons und dessen Eigenschaften werden beschrieben. Es wird gezeigt, daß das Reagens im sauren Medium mit Zirkonium mehrere Komplexe bildet, darunter einen mit der Zusammensetzung 1∶4. Dieser bevorzugt bei Fluoronüberschuß gebildete Komplex besitzt den extrem hohen Extinktionskoeffizienten ɛ max=165000 l/Mol · cm und eignet sich vorzüglich zur Ausarbeitung eines photometrischen Bestimmungsverfahrens für Zirkonium. Im Konzentrationsbereich 0,4–10 nMol/ml liegen die Variationskoeffizienten des Verfahrens zwischen 0,5 und 2,8 Rel-%.
    Notes: Abstract A report is given on the preparation and properties of 2′-quinolylfluorone. In acid solution the reagent forms various complexes with zirconium. Owing to its extremely high extinction coefficient ɛ max=165000 the 1∶4-complex can be used for quantitative determination of zirconium. In the concentration range 0.4–10 nmoles/ml the variation coefficients are 0.5–2.8% rel.
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    URL: http://dx.doi.org/10.1007/BF00425785
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    Photometrische Bestimmung von Zirkoniumoxidchlorid in Speisesalz (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 265 (1973), S. 267-268 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Zirkoniumoxidchlorid in Natriumchlorid ; Spektralphotometrie ; Speisesalzanalyse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung 2′-Chinolylfluoron bildet mit Zirkonium einen 1∶4-Komplex, dessen Extinktionskoeffizient bei 539 nm ɛ max=165000 ist. Das Bestimmungsverfahren für ZrOCl2 in Speisesalz wird auf dieser Farbreaktion aufgebaut.
    Notes: Abstract 2′-Quinolylfluorone forms a 1∶4-complex with zirconium. Owing to its high extinction coefficient ɛ max=165000 at λ=539 nm the complex can be used for the determination of ZrOCl2 in table salt.
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    Spectrophotometric evaluation of formation constants. 1∶2 metal-ligand system: Iron(II)-quinolinic acid complex (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 265 (1973), S. 269-269 
    Details
    ISSN: 1618-2650
    Keywords: Bildungskonstanten des Komplexes Eisen(II)/Chinolinsäure ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00425787
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    Bestimmung geringer Mengen Phenol-2,4-disulfonsäure neben Phenol-4-sulfonsäure (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 265 (1973), S. 272-272 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Phenol-2, 4-disulfonsäure neben Phenol-4-sulfonsäure ; Spektralphotometrie ; Eisen(III)-komplex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00425791
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    Photometrische Bestimmung des Magnesiumgehaltes von Aluminiumlegierungen mit DHBTM (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 266 (1973), S. 343-348 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Magnesium in Aluminiumlegierungen ; Spektralphotometrie ; DHBTM als Reagens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Durch Kondensation von Malonaldehyd mit 4,6-Dioxohexahydropyrimidin (Dihydrobarbitursäure) bildet sich der Trimethinfarbstoff DHBTM. Er ist ein ausgezeichnetes, stabiles Reagens zur photometrischen Bestimmung von Magnesium. Seine Darstellung und seine Eigenschaften werden beschrieben. Die Magnesiumbestimmung beruht auf der Bildung einer Adsorptionsverbindung und ist weitgehend unabhängig von Störfaktoren, die bei ähnlichen Reaktionen von großem Einfluß sind. So läßt sich ohne voraufgehende Extraktion, lediglich unter Zuhilfenahme von Maskierungsmitteln ein Bestimmungsverfahren für Magnesium in Aluminramlegierungen ausarbeiten. Der Variationskoeffizient des Verfahrens liegt in der Größenordnung von 1 Rel.-%.
    Notes: Abstract The trimethine dye DHBTM, which can be prepared by condensation of malonaldehyde and 4,6-dioxohexahydropyrimidine (dihydrobarbituric acid), is described as an excellent, stable reagent for a photometric determination of magnesium. The method is based on the formation of an adsorption compound. Interfering elements in aluminium alloys can be masked in a simple manner with no preceding extraction being necessary. The variation coefficient of the photometric method is ca. 1%-rel.
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    Photometrische Bestimmung von NH4OH in NH4F-Lösungen und NH4F-HF-Puffergemischen (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 266 (1973), S. 348-351 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Ammoniumhydroxid in Ammoniumfluorid-Pufferlösungen ; Spektralphotometrie ; Indicatoren der Phenolgruppe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Zur reproduzierbaren Herstellung von NH4F-HF-Ätzlösungen muß der Gehalt an NH4OH in den käuflichen 40% igen NH4F-Lösungen ermittelt werden. Hierzu wurde eine colorimetrische Methode unter Verwendung von pH-Farbindicatoren der Phenolgruppe ausgearbeitet, die geringe pH-Wertabweichungen (0,007 pH) vom Soll (0% NH4OH) zu messen erlaubt, wobei der Sollwert durch stabile Citronensäure-Phosphatpuffer simuliert wird. Durch Extinktionsmessung gelingt es, 0,01% NH4OH in NH4F-Lösungen zu erfassen. Die gefundenen Werte liegen zwischen 0,1–0,3%.
    Notes: Abstract To obtain NH4F-HF etching agents with constant etching behaviour the concentration of NH4OH in commercially available 40% NH4F solutions has to be measured. By application of pH-indicators of the phenol type very small pH-deviations (0.007 pH) from the specified value (0% NH4OH) can be measured. The specified value is simulated by the stable McIlvaine buffer. By determining the differences in optical absorption 0.01% NH4OH can be measured in NH4F solutions. Values found in practice are between 0.1– 0.3%.
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    Extraction-photometric determination of titanium (IV) by synergism with pimelyl-bis-N-phenylhydroxamic acid (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 266 (1973), S. 364-365 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Titan(IV) mit Pimelyl-bis-N-hydroxamsäure ; Spektralphotometrie ; Synergist, m. NH4SCN
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00423768
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    Über eine allgemein anwendbare Methode zur Bestimmung von Aluminiuni in Stahl (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 267 (1973), S. 13-16 
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    ISSN: 1618-2650
    Keywords: Best. von Aluminium in Eisen, Stahl ; Spektralphotometrie ; Aluminonmethode nach Extraktionen und Elektrolyse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Das beschriebene photometrische Verfahren wurde für Al-Gehalte von 0,01–1,1% in Eisen, Stählen und Edelstählen ausgearbeitet und an Teststählen überprüft. Mit Hilfe einer Hg-Elektrolyse und schrittweise vorgenommenen Extraktionen der die Al-Bestimmung störenden Legierungsbestandteile (wie Fe, Mo, Cr, Cu, Co, Cd, Mo, Pb, Ni, Sb, Zn, Sn, Mn) wird das Aluminium mit 8-Hydroxychinolin bei pH 9 abgetrennt und nach einem HNO3/H2SO4-Aufschluß photometrisch nach der Aluminonmethode bestimmt.
    Notes: Abstract The method has been worked out for Al contents from 0.01 to 1.1% in iron, steels and alloy steels, and tested with standard reference materials. Aluminium is separated by 8-hydroxy-quinoline at pH 9 after Hg-electrolysis and step-wise pre-extraction of interfering constituents as Fe, Mo, Cr, Cu, Co, Cd, Mo, Pb, Ni, Sb, Zn, Sn, Mn. Finally the 8-hydroxy-quinoline extract is digested with nitric/sulphuric acid and aluminium is determined spectrophotometrically by the Aluminon method.
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    Spektralphotometrische Bestimmung von Carbonylverbindungen über die 2,4-Dinitrophenylhydrazone (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 267 (1973), S. 44-44 
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    ISSN: 1618-2650
    Keywords: Best. von Carbonylverbindungen mit 2,4-Dinitrophenylhydrazin ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00635417
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    Zur Jodbestimmung im Nanogrammbereich nach der Sandell-Kolthoff-Reaktion (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 267 (1973), S. 89-95 
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    ISSN: 1618-2650
    Keywords: Best. von Jod in Pflanzenmaterial, Filterpapier ; Spektralphotometrie ; ng-Bereich, Sandell-Kolthoff-Reaktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Bei einem Verfahren zur Jodbestimmung in Biomatrices auf Grund der Sandell-Kolthoff-Reaktion wurden der alkalische Aufschluß sowie weitere Verfahrensschritte mit 131J-Tracer auf Jodverlust und Reproduzierbarkeit überprüft und eine modifizierte Arbeitsvorschrift ausgearbeitet. Bei Grasproben wurde eine Standardabweichung von 7% ermittelt.
    Notes: Abstract A method for the determination of iodine in biological materials based on the Sandell-Kolthoff reaction has been studied. For the alkaline mineralization and some further steps with regard to iodine losses and reproducibility 131I tracer was applied and a modified procedure has been developed. In the case of grass samples the standard deviation is found to be 7%.
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    Bestimmung des O/U-Verhältnisses von nichtstöchiometrischem Urandioxid mit Hilfe der Spektralphotometrie (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 267 (1973), S. 103-105 
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    ISSN: 1618-2650
    Keywords: Best. des O/U-Verhältnisses von nichtstöchiometr ; Urandioxid ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine Methode zur Bestimmung des Sauerstoff-Metall-Verhältnisses von überstöchiometrischem Urandioxid wird beschrieben. Nach Auflösen des Urandioxids in heißer konzentrierter Phosphorsäure werden die Konzentrationen an U4+ und U6+ über die Messung der Extinktionen zweier spezifischer Wellenlängen bestimmt. Die Methode zeichnet sich durch Einfachheit und geringen Zeitaufwand aus. Sie wurde für O/U-Verhältnisse von 2,05–2,67 getestet. Die Reproduzierbarkeit beträgt, bezogen auf das O/U-Verhältnis, ±0,005.
    Notes: Abstract After dissolution of the sample in hot concentrated phosphoric acid the concentrations of U4+ and U6+ are measured via the absorbance of two specific wavelengths. The method is simple and requires little time. It has been tested for 0/U ratios 2.05 to 2.67. The reproducibility, related to the O/U ratio, is ± 0.005.
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    Bestimmung von Phthalsäureestern in wäßrigen Weich-PVC-Extrakten mittels Dünnschicht-Chromatographie (1973)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 267 (1973), S. 127-128 
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    ISSN: 1618-2650
    Keywords: Best. von Phthalsäureestern in Polyvinylchlorid, Weichmachern ; Chromatographie, Dünnschicht ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine dünnschicht-chromatographische Methode zur quantitativen Bestimmung von Phthalsäureestern in wäßrigen Weich-PVC-Extrakten wurde entwickelt. Als Lösungsmittel dient Petroläther-Diäthyläther-Eisessig (8∶2∶0,1); die Beschichtung besteht aus 0,2 mm Silicagel mit Fluorescenzzusatz. Nach Auftrennung und Elution erfolgt eine photometrische Auswertung.
    Notes: Abstract A thinlayer chromatographic method for the quantitative determination of phthalic acid esters in aqueous PVC-plastic extracts has been developed. Petroleum ether/diethyl ether/glacial acetic acid (8∶2∶0.1) is used as solvent; the plates are coated with 0.2 mm of silica gel with fluorescent agent. After separation and elution a photometric determination is performed.
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    Spectrophotometry of the platinum metals in the ultraviolet region (1973)
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    Fresenius' Zeitschrift für analytische Chemie 267 (1973), S. 288-288 
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    ISSN: 1618-2650
    Keywords: Best. von Platin(IV) ; Spektralphotometrie ; UV-Bereich
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00425305
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    Über die Struktur der Pilzkörper des Insektenhirns (1972)
    Springer
    Cell & tissue research 127 (1972), S. 240-257 
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    ISSN: 1432-0878
    Keywords: Insects ; Brain ; Corpora pedunculata ; α-lobe ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Organisation der α-Loben der Pilzkörper im Gehirn von Acheta domesticus L. wird nach licht- und elektronenmikroskopischen Befunden beschrieben. Der säulenartige Faserkomplex des α-Lobus besteht aus Fortsätzen von Pilzkörperzellfasern (intrinsischen Fasern, IF) und pilzkörperfremden Fasern (extrinsischen Fasern, EF), die in den Lobus eindringen. Die feinen IF durchziehen den Lobus hauptsächlich parallel zu seiner Längsachse, während die EF zumeist senkrecht zur Längsachse angeordnet sind. Der Lobus erscheint von seiner Peripherie bis zu seinem Zentrum durch IF-Zonen gegliedert. Die Verteilung der EF weist auf eine zusätzliche Ordnung von der Basis zur Spitze des Lobus hin. Zahlreiche polarisierte Synapsen verbinden IF mit EF. Die IF zeigen Vesikelanhäufungen und präsynaptische Apparate besonders in Erweiterungen, die auch in Golgi-Präparaten lichtmikroskopisch zu sehen sind. Es werden zwei EF-Typen unterschieden: 1. Postsynaptische EF (zahlreich) und 2. EF mit prä- und postsynaptischen Kontakten, die nur in einigen Regionen des α-Lobus gefunden wurden. Präsynaptische IF konvergieren auf „dendritische“ EF, die Verbindungen mit anderen Teilen des Hirns und des Nervensystems herstellen. Funktionelle Gesichtspunkte werden diskutiert.
    Notes: Summary The organization of the α-lobes of the corpora pedunculata in the brain of the cricket Acheta domesticus L. has been investigated in the light and electron microscopes. The cylindrical fibre complex is composed of branches of “mushroom-body” fibres (intrinsic fibres) and extrinsic fibres, which penetrate the α-lobe. Intrinsic fibres (IF) run through the α-lobe in the same direction, but not strictly parallel to each other or to the axis of the α-lobe. Extrinsic fibres (EF) and their fine branches are often arranged perpendicular to the axis of the α-lobe. There is some evidence that different IF zones occur in the α-lobe when passing from its periphery to its centre. The distribution of EF may reflect a structural order when passing from the base of the lobe to its top. Numerous polarized synapses connect the IF with the EF. The IF show clusters of vesicles and presynaptic figures especially in their “blebs”, which can be seen in Golgi preparations for light microscopy. Two types of EF are distinguished on the basis of their synaptic junctions: (1) postsynaptic EF (abundant) and (2) EF with pre- and postsynaptic sites (perhaps restricted to some regions of the α-lobe). Presynaptic IF converge on EF, which may transfer excitation from the α-lobe to different parts of the brain and nervous system.
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    Synapses of crayfish abdominal ganglia with special attention to afferent and efferent connections of the lateral giant fibers (1972)
    Springer
    Cell & tissue research 127 (1972), S. 526-544 
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    ISSN: 1432-0878
    Keywords: Synapses ; Crustacea ; Abdominal Ganglia ; Lateral glant fibers ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The abdominal ganglia of the crayfish Astacus pallipes contain numerous vertebrate-like synapses which are characterized by presynaptic vesicles, darkened pre- and post-synaptic membranes, cleft material, and post-synaptic “fuzz”. Such synapses occur throughout the ganglia but are most easily found dorsally, where the neuropile is relatively coarse. The neuropile is far from homogeneous. Regional variations in fiber size, in degree of profile tortuosity, and in kind, magnitude, and distribution of vesicular content result in conspicuous textural variations. The structural polarity of synapses between the lateral giant fibers and other neurons is consistent with known physiological polarity and, hence, validates our criteria for recognition of synapses within the ganglion.
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    Further studies on synaptic junctions (1972)
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    Cell & tissue research 125 (1972), S. 415-431 
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    ISSN: 1432-0878
    Keywords: Synapses ; Rat ; Cerebral cortex ; Glutaraldehyde/E-PTA ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Synaptic junctions in intact rat cerebral cortex have been examined following glutaraldehyde fixation and phosphotungstic acid (PTA) staining. In the presynaptic ending the network has a hexagonal arrangement, while the dense projections are regularly placed along the presynaptic membrane. Cleft densities occupy the intracleft region. The postsynaptic thickening extends uninterrupted along the length of the junction. Qualitatively, the majority of junctions fall into the ‘discontinuous-continuous’ category, in which the internal coat of the presynaptic membrane together with its associated dense projections is discontinuous along the length of the junction, whereas the postsynaptic thickening is continuous. By contrast, a small number of junctions are ‘continuous-continuous’. In an attempt to analyze the junctions quantitatively, nine indices were measured. Histograms of the size distributions of seven of these appear to be bimodal, and from this it is concluded that two junction populations may be distinguishable on quantitative grounds. It is also shown that the distance separating dense projections at the presynaptic membrane is of the order of 10–15 nm. This surprisingly low value has consequences for current ideas on the relationship between synaptic vesicles and dense projections, and these are discussed at length.
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    Further studies on synaptic junctions (1972)
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    Cell & tissue research 125 (1972), S. 432-447 
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    ISSN: 1432-0878
    Keywords: Synaptosomes ; Synapses ; Rat ; Cerebral cortex ; Glutaraldehyde/E-PTA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Working with glutaraldehyde fixed, PTA stained rat cerebral cortex, the authors compared the ultrastructural features of synaptosomes with those of intact synaptic junctions. In general there is close correspondence between the two, although the cleft densities and postsynaptic focal densities of synaptosomes show a greater degree of focalization than their counterparts in synaptic junctions. The dense projections have similar profiles in both preparations, but are more difficult to distinguish clearly in synaptosomes on account of the closer packing of the presynaptic network around their apices. The limiting membrane of the presynaptic terminal is usually visible in synaptosomes, but not in synaptic junctions. Comparing the preparations quantitatively reinforces the qualitative findings, and points to their overall similarity. However a number of the indices in synaptosomes are significantly smaller than the corresponding ones in synaptic junctions, and this points to the operation of a shrinkage factor during fractionation procedures. This is confined to the pre- and post-synaptic components and does not affect the intervening contact region. Histograms of the size distributions of the indices are similar to those obtained for intact synaptic junctions, the majority displaying two peaks. It is concluded that synaptosomes accurately reproduce the major ultrastructural features of synaptic junctions.
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    Innervation and vascular supply of the crayfish opener muscle: Scanning and transmission electron microscopy (1972)
    Springer
    Cell & tissue research 127 (1972), S. 189-200 
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    ISSN: 1432-0878
    Keywords: Crustacean ; Muscle ; Nerve ; Blood vessel ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to study the innervation and vascular supply of crayfish skeletal muscle. Blood vessels and nerve terminals identified by TEM were often closely associated. Synaptic regions of the nerve terminals were always located under sarcolemma and contained both dense-cored and agranular synaptic vesicles. Axo-axonal synapses of several different types were observed. Blood vessels consisted of several “vessel cells” or “supporting cells” enclosing a lumen, which was connected to the exterior by fine channels between the “supporting cells”. SEM of whole freeze-dried muscles revealed two types of ramifying structure, which often ran in parallel over the muscle surface. One, identified as nerve, was more cylindrical and had a smoother surface than the other, which was identified as blood vessel. Fine nerve branches disappeared under the sarcolemma, probably near synaptic regions, but synapses could not be seen. Blood vessels also had fine terminations which merged into the sarcolemma.
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    The lorenzinian ampullae of Polyodon spathula (1972)
    Springer
    Cell & tissue research 130 (1972), S. 362-377 
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    ISSN: 1432-0878
    Keywords: Lorenzinian ampullae ; Polyodon spathula ; Sensory epithelium ; Synapses ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light and electron microscopic observations on the ampullary organs of Polyodon spathula (Chondrostei, Osteichthyes) reveal a sensory epithelium similar to that found in the Lorenzinian ampulla, an electroreceptor found in marine Elasmobranchs. The sensory cells have a very small luminal part provided with a cilium. They are innervated by many nerve endings. Each nerve fibre apparently makes synaptic contact with several sensory cells. The synaptic structure in the sensory cell is composed of a flat sheet, the outermost part of which is surrounded by 3 or 4 annuli of densely staining material. The sheet extends into a protrusion of the sensory cell, and there is a corresponding invagination in the nerve terminal. The conclusion that these organs are electroreceptors, is supported by the finding that the fish responds to the introduction of an iron tube in the aquarium, whereas a wooden rod introduced in the same way causes no response.
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    Ultrastructure of neuromuscular junctions in Limulus heart (1972)
    Springer
    Cell & tissue research 130 (1972), S. 481-488 
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    ISSN: 1432-0878
    Keywords: Limulus heart ; Neurogenic heart ; Neuromuscular junctions ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural characteristics of the neuromuscular junctions were studied in the neurogenic heart of Limulus polyphemus. Several types were encountered. The first type consisted of nerve terminals which synapsed along the borders of the myocardial fibers, embedded just under the sarcolemma. A second type of terminal was ensheathed in glial cells, synapsing on the outer sarcolemmal membrane. The third, and most prevalent type of junction consisted of terminals which synapsed with arms of granular sarcoplasm, remote from the fibrillar portion of the muscle fibers. Junctional complexes of the third type were often observed near intercalated discs and were often formed by several axons synapsing with arms of sarcoplasm from several muscle fibers. The results are discussed in relation to the previously reported electrophysiological characteristics of the neuromuscular junctions.
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    Spectrophotometric determination of rhodium with EDTA and CDTA (1972)
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    Fresenius' Zeitschrift für analytische Chemie 276 (1972), S. 72-72 
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    ISSN: 1618-2650
    Keywords: Best. von Rhodium mit ÄDTA, CDTA ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00423562
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    Über die Synapsenformen und das Vorkommen von Acetylcholinesterase in der Epiphyse von Bombina variegata (L.), (Anura) (1972)
    Springer
    Cell & tissue research 126 (1972), S. 278-296 
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    ISSN: 1432-0878
    Keywords: Anura ; Pineal organ ; Synapses ; Acetylcholinesterase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung In der Epiphyse von Bombina kommen durch „synaptic ribbons“ gekennzeichnete Synapsen und konventionelle Synapsen vor. Bei den „ribbon“-Synapsen handelt es sich um axodendritische und axosomatische Formen. Die axodendritischen „ribbon“-Synapsen lassen sich aufgrund der Zahl der Dendriten und der „synaptic ribbons“ in 2 Typen gliedern. Es kommen Dendriten vor, die nacheinander in „ribbon“-Synapsen und konventionelle Synapsen einbezogen sind. Neben konventionellen und durch „ribbons“ gekennzeichneten synaptischen Verbindungen finden sich weitere Kontakte zwischen Sinnes- und Nervenzellen und Interrezeptorkontakte, die jedoch beide nicht als echte Synapsen angesprochen werden können. Anhand der Befunde zur Synaptologie werden Probleme der neuronalen Schaltung der Epiphyse diskutiert. Beim Acetylcholinesterase-Nachweis findet sich das Reaktionsprodukt vor allem in den Neuropilzonen der Epiphyse. Eine eindeutige Zuordnung zu Fortsätzen bestimmter Zelltypen ist nicht möglich. Das Ergebnis des Acetylcholinesterase-Nachweises in der Epiphyse wird mit entsprechenden Befunden in anderen Bereichen des ZNS und in der Netzhaut verglichen.
    Notes: Summary Both conventional and ribbon synapses occur in the pineal organ of Bombina. Ribbon synapses are both axodendritic and axosomatic. Two axodendritic types can be distinguished on the basis of the number of dendrites and synaptic ribbons. Both conventional and ribbon synapses can be formed with the same dendrite. Other contacts, which cannot be classified as true synapses, are also found between sensory cells and nerve cells and likewise between sensory cells. The synaptology of the pineal organ permits a discussion of the problems of its neurocircuitry. Products of the acetylcholinesterase reaction occur mainly in the plexiform layer of the pineal organ. It is not possible to correlate the reaction products with definite cell types. The results of the acetylcholinesterase reaction in the pineal is compared with corresponding findings in other parts of the CNS and in the retina of the lateral eyes.
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    Bestimmung von Aluminium und Calcium in den hochschmelzenden Metallen Wolfram und Molybdän durch Atomabsorptions-Spektrometrie (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 261 (1972), S. 108-112 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Aluminium und Calcium in Wolfram und Molybdän ; Spektralphotometrie ; Atomabsorption ; ohne vorhergehende Abtrennung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Das Atomabsorptionsverhalten von Aluminium und Calcium in Wolfram und Molybdän wurde untersucht. Es zeigt sich, daß die Störungen durch die Matrixelemente wesentlich von der Geometrie des Brenners abhängen. Aluminium und Calcium können ohne vorherige Trennungsoperationen mit der Atomabsorptions-Spektrometrie in Wolfram und Molybdän bestimmt werden. Die Empfindlichkeit betrug 0,3 μg Al/ml und 0,04 μg Ca/ml Lösung bzw. 3 ppm Al und 0,4 ppm Ca im festen Metall.
    Notes: Abstract Results of the atomic-absorption behaviour of aluminium and calcium in tungsten and molybdenum are reported. There is a marked influence of the geometry of the burner on the interference of the matrix elements. As can be applied without prior separation procedures for the direct determination of aluminium and calcium in tungsten and in molybdenum. The sensitivity found was 0.3 μg Al/ml and 0.04 μg Ca/ml of solution, resp. 3 ppm Al and 0.4 ppm Ca in the solid metal.
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    Spectrophotometric study of copper-formazan complex (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 261 (1972), S. 124-125 
    Details
    ISSN: 1618-2650
    Keywords: Untersuchung des Kupfer-Formazan-Komplexes ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00428077
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    Spectrophotometric determination of iron(III) with 5-sulpho-β-resorcylic acid (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 261 (1972), S. 126-126 
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    ISSN: 1618-2650
    Keywords: Best. von Eisen(III) ; Spektralphotometrie ; mit 5-Sulfo-β-resorcylsäure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00428079
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    Determination of trace elements in silicate rocks by atomic absorption spectrophotometry (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 261 (1972), S. 126-127 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Spurenelementen in Silicatgestein ; Spektralphotometrie ; Atomabsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00428080
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    Spektralphotometrische Bestimmung von Rubidium und Caesium (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 261 (1972), S. 392-392 
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    ISSN: 1618-2650
    Keywords: Best. von Rubidium und Caesium ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00787001
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    Automatisierte photometrische Bestimmung von Kupfer in Aluminium mit Natriumdiäthyldithiocarbaminat (Na-DDTC) (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 261 (1972), S. 394-394 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Kupfer in Aluminium ; Spektralphotometrie ; Na-DDTC, automatisiert
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00787004
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    Spektrophotometrische Bestimmung des Niobs mit Chloranilsäure (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 261 (1972), S. 400-400 
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    ISSN: 1618-2650
    Keywords: Best. von Niob mit Chloranilsäure ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00787010
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    Colorimetrische Bestimmung von Panthenol und Pantothenaten (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 262 (1972), S. 189-192 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Panthenol und Pantothenaten in Vitaminpräparaten ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine empfindliche Methode zur Bestimmung von Panthenol und Pantothenaten ist ausgearbeitet worden. Störende Begleitstoffe werden mit Hilfe von Ionenaustauschern entfernt. Hydrolyse und Farbreaktion erfolgen in einem Schritt, wodurch eine große Zeitersparnis erzielt wird. Die colorimetrische Bestimmung erfolgt durch Bildung eines N-substituierten Pyrrols und anschließende Reaktion mit p-Dimethylaminobenzaldehyd. Mengen von weniger als 0,5 mg Panthenol bzw. Pantothenat können in Multivitaminpräparaten bestimmt werden. Die relative Standardabweichung der Methode ist kleiner als ± 3%.
    Notes: Abstract A sensitive colorimetric method for the determination of panthenol and pantothenates was developed. Interfering substances can be eliminated by ion-exchange resins. Hydrolysis and colour reaction take place in one step. The time for the determination is reduced considerably. The colorimetric determination occurs by formation of a N-substituted pyrrole and reaction with p-dimethylaminobenzaldehyde. Quantities of less than 0.5 mg of panthenol or pantothenates can be determined in multivitamin preparations. The relative standard deviation of the method is less than ± 3%.
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    Hochselektive spektralphotometrische Schnellbestimmung von Beryllium mit Thorin (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 262 (1972), S. 273-275 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Beryllium mit Thorin ; Spektralphotometrie ; Verbesserung der Selektivität
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Durch einfache Maskierung mit großen Zusätzen an ÄDTA und Ammoniumcitrat konnte die Berylliumbestimmung mit Thorin wesentlich verbessert werden. Über 60 untersuchte Kationen und 20 Anionen stören die Bestimmung in weiten Grenzen nicht. Die relative Standardabweichung beträgt etwa ± 1%.
    Notes: Abstract The selectivity of the spectrophotometric determination of beryllium by thorin has been essentially improved by simply masking the other cations with large quantities of EDTA and ammonium citrate. Over 60 cations and 20 anions, which have been investigated, do not disturb the determination in a wide range. The relative standard deviation is about ± 1%.
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    Chemische Vitamin D3-Bestimmung in Lebertran (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 262 (1972), S. 278-282 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Vitamin D3 in Lebertran ; Spektralphotometrie ; Verseifung ; Extraktion ; Sterinfällung ; Chromatographie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es werden verschiedene Aspekte der Vitamin D3-Bestimmung an Hand der Literaturangaben diskutiert und erläutert. Die eigentliche spektralphotometrische Vitamin D3-Bestimmung erfolgt nach der alkalischen Verseifung, Extraktion der unverseifbaren Anteile, Fällung der begleitenden Sterine und nach der säulen- und dünnschicht-chromatographischen Trennung des Vitamins D3 auf 40 cm DC-Platten von anderen Vitaminen. Der Farbstoff α-Naphtholbenzein eignet sich besonders als Leitsubstanz für die bessere Lokalisierung der Vitamin D3-Zone an der DC-Platte. An Hand der gleichzeitig durchgeführten biologischen Versuche wurden die Ergebnisse kontrolliert.
    Notes: Abstract The different aspects of Vitamin D3 determination and the data reported in the literature are discussed. The spectrophotometric determination of Vitamin D3 in cod-liver oil is carried out after the alkaline saponification, extraction of unsaponified parts, precipitation of accompanying sterols and the column- and thin-layer chromatographic purification and separation of vitamin D3 on 40 cm plates from other vitamins. The dyestuff α-naphtholbenzein is suited well as standard substance for the better location and identification of vitamin D3 zone on the thin-layer plate. The results obtained from the chemical method were checked through the simultaneous biological determination.
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    Spectrophotometric determination of trace amounts of cobalt using 7-Nitroso-8-hydroxyquinoline-5-sulphonic acid as reagent (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 266 (1972), S. 127-127 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Kobalt mit 7-Nitroso-8-hydroxychinolin-5-sulfonsäure ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00424072
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    Spectrophotometric determination of iron(II) using pyrazine-2,3-dicarboxylic acid as reagent (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 276 (1972), S. 71-71 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Eisen(II) mit Pyrazin-2,3-dicarbonsäure ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00423561
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    Spectrophotometric determination of trace amounts of diethylene glycol in propylene glycol (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 276 (1972), S. 73-73 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Diäthylenglykol in Propylenglykol ; Spektralphotometrie ; Spuren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00423564
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    Spectrophotometric determination of traces of ethylene glycol in water (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 276 (1972), S. 73-73 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Äthylenglykol in Wasser ; Spektralphotometrie ; Oxidation zu Oxalsäure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF00423563
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    Spine-like astrocytic protrusions into large axon terminals (1971)
    Springer
    Cell & tissue research 115 (1971), S. 494-500 
    Details
    ISSN: 1432-0878
    Keywords: Axon ; Synapses ; Astrocytes ; Thalamus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopic studies and three-dimensional graphic reconstructions from serial sections have shown that the large axon terminals of synaptic glomeruli in the ventrobasal nucleus of the rat are invaginated by spine-like protrusions from the astrocyte processes surrounding the glomeruli (“micro-trophospongium”). The astrocytic protrusions are similar in dimensions and internal morphology to the synapse-bearing dendritic excrescences that also invaginate the large axon terminals. Consequently astrocytic protrusions may be overlooked, or confused with dendritic excrescences sectioned at a non-synaptic level. The intimate neuronal—neuroglial relationship at such large axon terminals may reflect ion-exchange or metabolic interactions between the astrocytes and the axon terminal.
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    Histotypic organization of the rat retina in vitro (1971)
    Springer
    Cell & tissue research 114 (1971), S. 557-579 
    Details
    ISSN: 1432-0878
    Keywords: Retina ; Tissue Culture ; Synapses ; Retinal Rods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Netzhäute von 2–3 Tage alten Ratten wurden in Plasma auf Deckgläsern in Rollerröhrchen zur Kultur angesetzt. Nach 7–17 Tagen in vitro wurden die Kulturen mit Aldehyden und Osmiumsäure fixiert und für elektronenmikroskopische Untersuchung weiterverarbeitet. Gewebsquerschnitte (senkrecht zum Deckglas) zeigten histotypische Organisation, besonders in den dickeren Abschnitten der Explantate. Die Schichtung der Zellen entwickelte sich ganz ähnlich derjenigen in der Retina in situ aus dem relativ primitiven ausgepflanzten Netzhautepithel, jedoch enthielten die verschiedenen Schichten weniger Zellen als in der Retina in vivo. Alle Hauptnervenzelltypen konnten auf Grund ihrer Lokalisation und ihrer cytologischen Merkmale unterschieden werden. Die Entstehung von membranösen Lamellen in den Außengliedern der Sinneszellen konnte als Einfaltung der Plasmamembran beobachtet werden. Synaptische Bandkomplexe in ausgereifter Form wurden in der äußeren plexiformen Schicht nachgewiesen, während konventionelle Synapsen in der inneren plexiformen Schicht häufig angetroffen wurden. Synaptische Bänder waren ebenfalls in den Axonen bipolarer Zellen in der inneren plexiformen Schicht nachweisbar. Amakrine und Ganglienzellen waren in diesen Regionen ziemlich selten vertreten. Da die Untersuchung von nicht kultivierten Netzhäuten drei Tage alter Tiere keinerlei Synapsen zeigte, wird geschlossen, daß die Synapsen in den Kulturen in vitro entstanden sein müssen. Die Netzhaut stellt ein günstiges Modell für die Synaptogenese in vitro dar, indem sie verschiedene Vorzüge vor Explantaten aus anderen Regionen des Zentralnervensystems aufweist, nämlich eine klare Schichtung, zahlreiche identifizierbare Zellfortsätze mit charakteristischen synaptischen Beziehungen und eine wohl definierte Folge von Entwicklungsvorgängen.
    Notes: Summary Retinae from two- and three-day-old rats were explanted in plasma clots and grown in vitro with the flying coverslip method. After seven to seventeen days in culture, the retinal tissue was fixed with aldehydes and osmium tetroxide and embedded for examination with the electron microscope. Study of cross sections (perpendicular to the coverslip) revealed a histotypic pattern of organization, especially in the thicker regions of the explants. Layering of cells quite similar to that in the intact retina was seen to develop from the relatively primitive, explanted retinal epithelium. However, each layer contained fewer cells than its counterpart in vivo. All major neuronal cell types were distinguished by their location and cytological characteristics. Development of the saccules of sensory cell outer segments was observed to occur in vitro by an infolding of the plasma membrane. Synaptic ribbon complexes developed to the mature form in the outer plexiform layers, while conventional synapses were numerous in the inner plexiform layers. Synaptic ribbons were also seen in bipolar cell axons in the inner plexiform layers. Amacrine and ganglion cells in these regions were relatively sparse. A survey of posterior regions of noncultured three-day-old rat retinae showed no synapses of any sort; therefore the synapses in the cultures formed in vitro. The retina is recommended for studies of synaptogenesis in tissue culture, for it offers several advantages over expiants from other areas of the neuraxis, including a clear layering pattern, many identifiable cell processes with characteristic synaptic relationships between them, and a well-defined sequence of developmental events.
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    Beitrag zur Kenntnis der Glomera coronaria der Katze (1971)
    Springer
    Cell & tissue research 118 (1971), S. 532-554 
    Details
    ISSN: 1432-0878
    Keywords: Glomera coronaria ; Cat ; Chemoreceptor cell ; Blood supply ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Gefäße der zwischen Aorta ascendens und Truncus pulmonalis, an der Vorder- und Hinterwand des Truncus pulmonalis gelegenen Glomera, sowie das sogenannte „Glomus pulmonale“ der Katze lassen sich von den Coronararterien aus durch Tusche-Gelatine-Lösungen füllen. Die erwähnten Paraganglien sind als Chemoreceptorenfelder dem Coronarkreislauf angeschlossen und daher als Glomera coronaria zu bezeichnen. Licht- und elektronenmikroskopische Untersuchungen ergaben eine morphologische Übereinstimmung mit dem Glomus caroticum. Vagusdurchtrennungen verursachen eine Degeneration der an den Glomuszellen gelegenen synaptischen Formationen sowie Veränderungen in Glomuszellen.
    Notes: Summary The vessels of the glomera that lie between the aorta and the pulmonary trunk, on the anterior and posterior wall of the pulmonary trunk, as well as the so-called glomus pulmonale of the cat have been injected with gelatine-india ink mixture. The paraganglia mentioned above are associated with the coronary circulation as chemoreceptors and are designated as the glomera coronaria. The investigations demonstrate a morphologic similarity with the glomus caroticum. Section of the vagus causes a degeneration of the synaptic structures on the glomus cells as well as changes in the cells themselves.
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    On the neurons and synapses of the lateral geniculate nucleus of the monkey, and the effects of eye enucleation (1971)
    Springer
    Cell & tissue research 113 (1971), S. 396-419 
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    ISSN: 1432-0878
    Keywords: Lateral geniculate nucleus ; Synapses ; Interneuron ; Transneuronal degeneration ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two neuron types are distinguished by electron microscopy in the lateral geniculate nucleus (LGN) of the monkey-a large cell (P cell) interpreted as a geniculostriate relay cell, and a small cell (I cell) interpreted as an inhibitory interneuron. The I cell, distinguished by its small size, infolded nucleus, small mitochondria, cilium and small granular bodies, forms about 10% of the total neuron population. It could not be determined whether this cell has an axon, but its dendrites, which contain aggregates of flattened vesicles, are thought to form a proportion of the “F processes”, profiles which are post-synaptic to the retinal (RLP) axons and presynaptic to the dendrites of the P cells. The small dark (RSD) axon terminals of unknown origin contact the dendrites of both cell types. After eye enucleation the P cells of the affected laminae of the LGN shrink and partially withdraw their dendrites from the neuropil. By 29 months' survival, they have only a narrow cytoplasmic rim around the nucleus. A necrotic process also occurs, affecting fine dendrites by 22 days and large profiles by 45 days, but it is not clear whether whole cells are destroyed by this process. At 45 days the I cells are commonly seen to form somatodendritic synapses. The appearance of these synapses is interpreted as the result of a withdrawal to the soma of the presynaptic dendrites. It is concluded that the I cells are probably inhibitory interneurons subject to excitation and presynaptic inhibition by the RLP and RSD axons, and a diagram is presented to demonstrate the possible significance of these connections for the transmission of information through the LGN.
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    URL: http://dx.doi.org/10.1007/BF00968547
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    Microtubule-associated smooth endoplasmic reticulum in the frog's brain (1971)
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    Cell & tissue research 116 (1971), S. 564-577 
    Details
    ISSN: 1432-0878
    Keywords: Axons ; Dendrites ; Microtubules ; Endoplasmic Reticulum ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopic studies of neural processes in the cerebellum, optic tectum, and cerebral hemisphere of the frog reveal a distinctive system of SER cisternae lying at intervals (commonly 1–2 μm apart) perpendicular to the long axis of axons and dendrites, interconnected by tubular, longitudinally orientated SER elements, and in direct continuity with the outer membrane of mitochondria. The transverse cisternae are fenestrated, with a single mierotubule (or rarely, two) passing through the centre of each 50–75 nm fenestration. Extensions of the SER-microtubule complex may be located parasynaptically in axon terminals and dendrites. The SER of dendritic spines also appears to be continuous with the fenestrated cisternae. Possible roles for the specialized SER (particularly of the parasynaptic extensions), such as calcium ion sequestration and ATP or monoamine oxidase transport, are discussed.
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    Observations on cerebellar granule cells in tissue culture (1970)
    Springer
    Cell & tissue research 107 (1970), S. 454-465 
    Details
    ISSN: 1432-0878
    Keywords: Cerebellum ; Neuron ; Synapses ; Myelin sheath ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In long-term organized cultures of newborn mouse cerebellum, granule cell neurons were studied with silver impregnation and electron microscopy. In silver impregnated cultures, small neurons are defined as granule cell neurons from their size, morphology and location. There are also occasional large nerve endings with the morphology typical of mossy fiber endings. In correlative electron micrographs, granule cell neurons revealed a faithful reproduction of characteristic structures seen in vivo. The fine structural details of cerebellar glomeruli and myelinated granule cell bodies developed in vitro were also described.
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    URL: http://dx.doi.org/10.1007/BF00335434
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    Possible axo-axonal synapses between peripheral adrenergic and cholinergic nerve terminals (1970)
    Springer
    Cell & tissue research 107 (1970), S. 508-521 
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    ISSN: 1432-0878
    Keywords: Synapses ; Axo-axonal ; Adrenergic and cholinergic terminals ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The relations between adrenergic and cholinergic terminals were studied in rat iris and rat heart with the electron microscope. Adrenergic terminals were identified by treating the animals with 5-hydroxydopamine, which produces dense-cored synaptic vesicles in adrenergic terminals in tissues fixed in glutaraldehyde and osmium. The specificity of this observation was verified. It was found that adrenergic and cholinergic nerve terminals often come in close contact with one another, the distance between the adjoining membranes being about 250 Å. At times, faint membrane thickenings could be observed in these places. The available pharmacological, physiological, and morphological evidence leaves little room for doubt that cholinergic terminal fibres can influence the adrenergic fibres. From mainly morphological evidence, it is also postulated that adrenergic terminals influence cholinergic ones.
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    Über neuritenähnliche intraventrikuläre Fortsätze und ihre Kontakte mit dem Ependym der Seitenventrikel der Katze (1970)
    Springer
    Cell & tissue research 111 (1970), S. 572-585 
    Details
    ISSN: 1432-0878
    Keywords: Brain ; Intraventricular cellular processes ; Ependyma ; Lateral ventricle ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Ependym und subependymale Strukturen der Seitenventrikel von Katzen aus dem Bereich des Nucleus caudatus und des Corpus callosum wurden nach Perfusionsfixierung elektronenmikroskopisch untersucht. Dort findet sich eine Reihe von Neuritenanschnitten, deren kolbenförmige Auftreibungen leere Vesikel, “dense core granula” und Mitochondrien enthalten. Neben diesen neuronalen Elementen werden auch Zellfortsätze nichtneuronaler Natur im Ventrikellumen beobachtet, die Ependym- und intraventrikulären Zellen entstammen. An umschriebenen Stellen nehmen diese kolbig aufgetriebenen Fortsätze desmosomenartige Kontakte mit dem Ependym auf. An diesen Orten umgeben Mikrovilli die Fortsätze korbartig. Ob es sich bei diesen Kontakten um synapsenartige Strukturen handelt, oder um „Rezeptoren“ für unbekannte chemische Stoffe, wird diskutiert. Die Kontakte sind unabhängig von der Form der Ependymzellen und davon, ob diesen graue oder weiße Substanz unterliegt. Zwischen und in den Ependymzellen finden sich — bedingt durch den unterschiedlichen Gehalt an Zellorganellen — drei verschiedene Arten von Fortsätzen. Die Zahl der neuronalen Fortsätze in diesem Bereich ist sehr viel kleiner als im Ventrikellumen.
    Notes: Summary Ependyma and subependymal regions of the lateral ventricles of cats (area of Nucleus caudatus and Corpus callosum) were fixed by perfusion and investigated electronmicroscopically. Intraventricular axons showing a beaded shape with smaller and thicker parts were found. The varicosities contain empty vesicles, dense core granules and mitochondria. Beside those certainly neuronal elements there exist intraventricular cell processes originating from ependymal cells and free cells. The neuronal processes make desmosome-like contacts with the ependyma. These regions of contact are surrounded by basket-like arranged microvilli. It is discussed, whether the contacts function like synapses or as receptors for a substance, which is still unknown. Contacts do not depend on the shape of ependymal cells. They exist with the ependyma of Nucleus caudatus (grey substance) as well as with the ependyma of Corpus callosum (white substance). Because of the different contents of cell-organelles one can differentiate three different sorts of processes situated inter- or intracellularly in the ependyma. Neuronal processes within the lateral ventricles are more numerous than those found within the ependymal layer.
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    The postnatal development of the synapse: A morphological approach utilizing synaptosomes (1970)
    Springer
    Cell & tissue research 111 (1970), S. 179-194 
    Details
    ISSN: 1432-0878
    Keywords: Synaptosomes ; Rat cerebral cortex ; Synapses ; Postnatal development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Synaptosomes (nerve-ending particles) prepared from the cerebral cortex of rats, aged 2–21 days, were examined after fixation in glutaraldehyde and osmium tetroxide, in order to study the development of the contact region between their pre- and postsynaptic components. Synaptosomes were present at all ages studied, although they increased in number and underwent morphological changes, e.g. a decrease in ribosomes and increase in synaptic vesicles, during development. The seventh postnatal day appeared to be a critical period for development, as many adult features were first observed at this time. The synaptic contact region was characterized by desmosome-like symmetrical thickenings until the fourth postnatal day, after which it became increasingly asymmetrical. The postsynaptic thickening, which had been undifferentiated until the seventh day, underwent a focalization of its material at this stage to form postsynaptic densities typical of the adult synapse. Cleft material was present at all ages, although for the first few days it was sparse and comparatively unorganized. An attempt has been made to distinguish between synaptosomes derived from axosomatic and axodendritic endings. The possible significance of the early desmosome-like thickenings is discussed, and the role of the cleft material and post-synaptic densities in the development of the synapse is analysed.
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    Morphology of superficial postnatal cerebral cortex with special reference to synapses (1970)
    Springer
    Cell & tissue research 110 (1970), S. 540-558 
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    ISSN: 1432-0878
    Keywords: Cerebral cortex ; Synapses ; Rat ; Postnatal differentiation ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of layers I and II of the motor cerebral cortex of rat brain has been studied at birth, 4, 7 and 14 days postnatal and in the adult. Compared with the adult, neonatal rat motor cortex exhibited a large extracellular space which decreases with increasing age. At all stages studied the neurons were seen to contain the organelles usually found in adult neurons. Growth cones were present in decreasing numbers up to 14 days old. Synapses were detectable at birth and there was an obvious increase in their number throughout the postnatal development. At the earliest stages studied there was a lack of specialization characteristic of the adult. Many synapses were either avesicular or relatively so and lacked the high degree of modification of adult pre- and postsynaptic membranes. By 7 days after birth many synapses existed which in all morphological respects resembled those of the adult, and by 14 days, the majority were of the adult type. These findings, particularly with reference to the postnatal development of synapses, have been discussed in relation to the known electrophysiological findings.
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    Ultrastructural features of the synaptic complex of the vestibular nuclei of Lampetra planeri (Bloch) (1970)
    Springer
    Cell & tissue research 108 (1970), S. 282-296 
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    ISSN: 1432-0878
    Keywords: Synapses ; Complex ; Nuclei vestibulares ; Lampetra planeri
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The vestibular fibres of ammocoetes of Lampetra planeri form a peculiar type of synaptic contact with the large nerve cells of the vestibular nuclei. In fact, a large expansion of the fibre is enveloped by the nerve cell cytoplasm, which makes a sort of spoon or actual channel by sealing its own plasma membrane with adhesion plaques around the fibre. In the whole area of juxtapposition between the fibre and the cell membranes, three different types of specialized contacts occur: desmosomoid junctions, which are the most numerous; zones having the characteristics of chemically active synapses on account of the presence of vesicles clustered on the presynaptic side; gap-junctions, where electrical transmission might occur. A puzzling feature is the presence of an enormous number of presynaptic vesicles located in the central part of the axoplasm of the fibre expansion.
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    Synapsen im Antennenhügel von Locusta migratoria (Orthoptera, Insecta) (1970)
    Springer
    Cell & tissue research 108 (1970), S. 563-581 
    Details
    ISSN: 1432-0878
    Keywords: Insect ; Brain ; Deutocerebrum ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Feinstruktur des Glomerulineuropils im Antennenhügel (sensorisches Zentrum) der Wanderheuschrecke Locusta migratoria wird beschrieben. Die Glomeruli stellen ein kompliziertes Netzwerk von sensorischen Antennennervenfasern und interneuronalen hirneigenen Elementen dar. Die Nervenfasern sind in ihrer großen Mehrheit von klaren synaptischen Vesikeln gefüllt, die sich mit Zinkjodid-Osmiumsäure färben (Akert und Sandri, 1968). Zwei Synapsentypen treten auf, die sich vor allem durch die Form und Ausdehnung des Synapsenspaltes unterscheiden. Beide Typen zeigen eine morphologische Polarität. Paramembranöses synaptisches Material läßt sich besonders deutlich mit der Wismutjodid-Methode von Pfenninger et al. (1969) darstellen. Diese Methode, die den gleichen Effekt wie bei Wirbeltieren zeigt, scheint zur Beurteilung synaptischer Verhältnisse (Verteilung, Häufigkeit) besonders geeignet. Normalerweise sind über synaptische Kontakte drei aneinandergrenzende Nervenfasern miteinander verknüpft. Obwohl Degenerationsexperimente vorgenommen wurden, konnte die synaptische Verschaltung der verschiedenen Fasern nur teilweise geklärt werden. Sensorische Fasern sind mit interneuronalen Fortsätzen verbunden, die prä- und postsynaptische Zonen haben. Es gibt einige Hinweise, daß auch sensorische Fasern miteinander synaptisch verknüpft sind. Vesikelfreie postsynaptische Elemente sind sehr selten, während eine synaptische Verbindung über „axo-axonale“ Kontakte häufig vorkommt. Die Antennalglomeruli mit ihrer großen Anzahl von kleinen, mit synaptischen Vesikeln gefüllten Fasern sind deutlich anders organisiert als die Glomeruli im Pilzkörperkelch (vgl. Lamparter et al., 1969).
    Notes: Summary The fibre anatomy of the glomeruli neuropil of the antennal lobes (sensory centres) of Locusta migratoria has been analysed by electron microscopy. The glomeruli consist of interneuronal and sensory elements of the antennal nerve, forming a complicated mesh-work of fine fibres. The great majority of nervous fibres is filled with clear synaptic vesicles, which stain with zinc-iodide-osmic-acid (Akert and Sandri, 1968), Two types of synaptic junctions are found, differing especially in shape and size of their synaptic gap. Both types show a clear morphological polarity, so that the distinction of pre- and postsynaptic fibres is possible. Inter- and intracellular paramembraneous synaptic material can be demonstrated by the bismuth iodide impregnation of Pfenninger et al. (1969) This method, showing the same effect as in vertebrate nervous systems, seems to be very adequate for the identification of synaptic structures and synaptic distribution. Normally presynaptic structures are situated in angles of nerve fibres. Although degeneration experiments were made, the synaptic interaction of the various fibre types could only partially be explained. Sensory fibres interact with intemeurons, which show pre- and postsynaptic zones. They seem to be responsible for the integration of different glomeruli. There is some evidence that sensory fibres have synaptic connections, too. Postsynaptic profiles with several synaptic contacts and free of vesicles are very rare, whereas “axo-axonic” contacts are found quite often. These glomeruli with their great number of vesicle-filled profiles differ from corpora pedunculata calyx glomeruli (see Lamparter et al. 1969).
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    Light and electronmicroscope study of one of the systems of centrifugal fibers found in the lamina of muscoid flies (1970)
    Springer
    Cell & tissue research 110 (1970), S. 336-349 
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    ISSN: 1432-0878
    Keywords: Nervous system ; Flies ; Intermediate retina (Lamina) ; Centrifugal fiber system ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary By combining the Golgi and the electronmicroscope techniques it has been possible to identify accurately the system of centrifugal fibers which arborizes in the lamina of muscoid flies forming the so-called nervous bags. Each of them originates from a single fiber entering the lamina at the site in which the second order and the long visual fibers leave it. This single fiber represents the peripheral portion of a T-shaped trunk stemming from a small neuronal body located in the external region of the medulla. The central branch terminates within the first synaptic field of this visual center. After entering the lamina the centrifugal fiber ramifies profusely and its branches can be seen climbing and synapsing on the surface of the photoreceptor axon endings. The synaptic loci show characteristic synaptic ribbons located within the nervous bag fibers. This fact suggests that direction of conduction is from the medulla to the lamina. This study has also revealed that the intramedullar terminals of the centrifugal fibers establish intimate contacts with one of the two second order fiber endings.
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    Quantitative studies of postnatal changes in synapses in rat superficial motor cerebral cortex (1970)
    Springer
    Cell & tissue research 110 (1970), S. 559-568 
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    ISSN: 1432-0878
    Keywords: Cerebral cortex ; Rat ; Synapses ; Postnatal ; Quantitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Quantitation of synapses at different postnatal ages has been undertaken in the cerebral cortex of the rat. In this study axial ratios of presynaptic bags, proportion of cortex occupied by presynaptic bags and numbers of synapses per unit volume of cortex have been estimated. Observations on synaptic vesicle packing densities have also been made. Synaptic bags become increasingly spherical up to 7 days of age and become more elongated thereafter. The proportion of cortex occupied by presynaptic bags increases rapidly up to 7 days of age and then at a decelerated rate up to maturity. The number of synapses per unit volume increases slowly over the first four days after which there is a rapid increase to 14 days, followed by a decelerated rate. The average presynaptic bag shows marked changes in volume with increasing age which indicate the probability of two stages of synaptic development. This two stage development is further reflected in the estimates on vesicle packing densities. The implications of the results are discussed in relationship to changes in functional activity of the cortex during postnatal development.
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    The postnatal development of the synapse: A morphological approach utilizing synaptosomes (1970)
    Springer
    Cell & tissue research 111 (1970), S. 195-208 
    Details
    ISSN: 1432-0878
    Keywords: Synaptosomes ; Rat cerebral cortex ; Glutaraldehyde/PTA ; Synapses ; Postnatal development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Synaptosomes derived from 2–21 days postnatal rat cerebral cortex have been examined following glutaraldehyde fixation and block PTA staining, with the aim of investigating the maturation of the paramembranous densities at the contact region between the pre- and postsynaptic components. The internal coats of pre- and postsynaptic membranes first appear as undifferentiated plaque-like thickenings, which gradually develop into, or are replaced by, dense projections and postsynaptic focal densities respectively. Both sets of densities pass through an interconnected phase before starting to emerge as discrete entities at 5–7 days. The external coats of the pre- and postsynaptic membranes coalesce to form a plate-like structure which breaks down during development to form the cleft densities or transverse bars of the adult contact region. Although for the first few days of postnatal development only one type of synaptosome can be identified, from 5 days onwards two types corresponding to types A and B of adult life become recognizable. Increase in height of the dense projections has been correlated with increase in the number of synaptic vesicles per synaptosome during postnatal development, indicating that the synaptic vesicles may play a role in the formation and maturation of dense projections. The possible importance of other factors in this process is also discussed.
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    The structure of the nerve fibre layer and neurocord in the enteropneusts (1970)
    Springer
    Cell & tissue research 103 (1970), S. 129-148 
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    ISSN: 1432-0878
    Keywords: Enteropneusts ; Nerve fibre ; Neurocord ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The nerve fibre layer and the neurocord of the Enteropneusts Saccoglossus horsti, Harrimania kupfferi and Ptychodera flava have been examined with the electron microscope. The nerve fibres vary in diameter between 0.15 to 10 μm. The majority of the fibres are of the smaller diameters. The nerve fibre layer is intraepidermal, and is divided by processes running radially from the epithelial cells to the basement membrane that separates the nerve fibre layer from the muscle cells. The cells of origin of these nerve fibres are situated mainly in the innermost layers of the epidermal cells. The nerve fibre profiles contain numerous vesicles of very varied diameter and contents, together with larger granular inclusions that are also found in the nerve cell bodies. Morphologically recognisable synapses are rare, but the majority of fibres are in intimate contact with one another. Sometimes the mass of fibres is divided into bundles by the epithelial cell processes. The majority of giant fibres are situated near to the basement membrane of the neurocord. The giant fibres also have a varied content of vesicles as well as neurofilaments and neurotubules. The central canal in Ptychodera flava and the remnants of the central canal in Saccoglossus horsti are both lined by columnar cells that bear microvilli as well as cilia with the typical 9 + 2 pattern of tubules. Scattered amongst these cells are mucus secreting cells which open into the cavity of the canal.
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    Über die Struktur der Pilzkörper des Insektenhirns (1970)
    Springer
    Cell & tissue research 103 (1970), S. 365-381 
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    ISSN: 1432-0878
    Keywords: Insects ; Brain ; Corpora pedunculata ; Mushroom bodies ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. Die Stiele der Corpora pedunculata im Gehirn von Acheta domesticus L. weisen eine Zonierung auf, die auf einer bestimmten Gruppierung von Globulizellfasertypen in der Stielsäule beruht. 2. Pilzkörperfremde Fasern durchziehen das Stielneuropil in allen Richtungen. Sie sind besonders klar zu erkennen, wenn sie senkrecht zu den Globulizellfasern verlaufen. 3. Sog. chemische Synapsen treten hauptsächlich in der Zone III, die den größten Teil des Stielvolumens einnimmt, und im basalen Stiel in der Zone IV auf. Außer synaptischen Vesikeln, die sich mit Zinkjodid-Osmiumsäure imprägnieren lassen, finden sich in den Pilzkörperfasern zahlreiche osmiophile Grana vom Typ der „dense core vesicles“. 4. Globulizellfasern sind mit pilzkörperfremden Fasern im Stiel synaptisch verknüpft. Sehr wahrscheinlich konvergieren im unteren Stielteil Globulizellfasern auf postsynaptische extrinsische Fortsätze. Wahrscheinlich haben auch Globulizellfasern untereinander synaptischen Kontakt. 5. Synaptische SpezialStrukturen (elektronendichte Auflagerungen, Massierungen von synaptischen Vesikeln) finden sich größtenteils in den anliegenden Winkeln von zwei benachbarten Axonen. Oftmals kann eine Entscheidung über die Polarisierung der Synapsen nicht getroffen werden. 6. Die verschiedenen Fasertypen und ihre Kontakte über Synapsen werden im Hinblick auf die Funktion der Corpora pedunculata diskutiert, die nach verbreiteter Ansicht assoziative Hirnzentren verkörpern.
    Notes: Summary 1. The stalk of the mushroom-bodies (Corpora pedunculata) of the cricket Acheta domesticus L. is composed of nerve fibers from different types of globuli cells. These fibers are arranged into four groups. 2. Extrinsic nerve fibers run through the pedunculus neuropil in different directions. 3. Synapses occur primarily in stalk zone III and in basic stalk parts of zone IV. Intrinsic nerve fibers of globuli cells contain synaptic vesicles, which stain with ZIO-impregnation (Akert and Sandri, 1968), and dense core vesicles. 4. Intrinsic and extrinsic nerve fibers make synaptic contacts. There is some evidence, that globuli cell fibers interact by chemical synapses too. 5. Special synaptic structures such as electron dense projections and accumulations of vesicles are situated predominantly in the angles of two neighbouring axons. The question of synaptic polarization can not always be resolved. 6. The different fiber types and their synaptic contacts are discussed with respect to the function of the corpora pedunculata. The results support the general view, that mushroom bodies represent an important brain center for association.
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    A further contribution to the study of the contact region of Octopus synaptosomes (1970)
    Springer
    Cell & tissue research 103 (1970), S. 48-60 
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    ISSN: 1432-0878
    Keywords: Synaptosomes ; Glutaraldehyde/PTA ; Synapses ; Octopus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Octopus synaptosomes have been examined after glutaraldehyde fixation and phosphotungstic acid (PTA) staining of non-osmicated tissue. The results concentrate on the appearance of the contact region between the presynaptic component of synaptosomes and their postsynaptic processes. Membranes have a triple-layered appearance, consisting of an electronopaque internal coat, an electrontranslucent band and an electronopaque external coat. Good examples of this are found in synaptosomal, dendritic and axonal membranes. At specialized synaptic contact regions the external coats of the pre- and postsynaptic membranes coalesce to form a prominent synaptic plate, which has a width of 18 nm and is subdivided into zones of varying electronopacity. It is suggested that this plate is formed from the specialized external coat of the postsynaptic membrane and the unspecialized external coat of the presynaptic membrane. Presynaptic spicules extend from the internal coat of the presynaptic membrane. They are closely associated with elements of the presynaptic network. It is suggested that the synaptic plate is probably composed of mucopolysaccharides, while the relation of the plate to acetylcholinesterase is discussed. It is proposed that functional localization at the synapse is less precise in octopus than vertebrates.
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    Weitere Untersuchungen zur Feinstruktur und Innervation des Pinealorgans von Passer domesticus L. (1970)
    Springer
    Cell & tissue research 105 (1970), S. 276-302 
    Details
    ISSN: 1432-0878
    Keywords: Pineal organ ; Passer domesticus ; Synapses ; Nervous pathway ; Sympathetic innervation ; Photo-neuro-endocrine organ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Im Parenchym der Epiphysis cerebri von Passer domesticus kommen Nervenzellen vor. Ihre Neuriten ziehen im langgestreckten Epiphysenstiel zur Commissura habenularum. Im proximalen Endabschnitt des Epiphysenstiels wird ein Teil dieser Fasern myelinisiert. Zwischen die Nervenfasern schieben sich zahlreiche Pinealocytenausläufer; synaptische Bänder helfen die letzteren eindeutig zu identifizieren. Im Bereich der synaptischen Bänder liegen: 1. 300 Å Vesikel, 2. 300 Å Vesikel und 800–1200 Å Granula, 3. nur 800–1200 Å große granulierte Vesikel. Die Tatsache, daß in Pinealocytenausläufern nebeneinander synaptische Bänder und Granula vorkommen, und daß apikal in zilientragenden Zellen ebenfalls Granula nachweisbar sind, spricht dafür, daß bei Passer domesticus ein Pinealzelltyp sensorische und sekretorische Strukturmerkmale besitzen kann. Außerdem werden Kontaktsynapsen beobachtet; ihre praesynaptischen Fasern enthalten die gleichen Strukturelemente wie die Fasern mit synaptischen Bändern. Die Zahl der Mikrofibrillen und Mikrotubuli variiert in den Pinealocytenausläufern, in den postsynaptischen Dendriten und in den Neuriten so stark, daß es mitunter schwierig ist, diese Fortsatztypen einwandfrei zu unterscheiden und die Zahl der zum Gehirn ziehenden Neuriten exakt zu ermitteln. Efferente sympathische Nervenfasern dringen in die Bindegewebssepten der Epiphyse ein. Sie enthalten Granula mit einem Durchmesser von 300–500 Å und 800–1200 Å. Nach Injektion von Nialamid zeigen beide Granulatypen einen elektronendichten Kern. Mikrospektrographisch ist Serotonin und Noradrenalin in diesen Nervenfasern nachweisbar. Das Material dieser Studie enthält keinen fluoreszenzmikroskopischen oder elektronenmikroskopischen Hinweis darauf, daß die sympathischen Nervenfasern durch die Basalmembran in den Zellverband des Epiphysenparenchyms eintreten. Im elektronenmikroskopischen Bild haben manche Pinealocytenausläufer eine Ähnlichkeit mit autonomen Nervenfasern. Die funktionelle Bedeutung der Vogelepiphyse als photo-neuro-endokrines Organ wird diskutiert.
    Notes: Summary The pineal organ of Passer domesticus contains nerve cells within its parenchyma. Axons of the nerve cells run within the elongated stalk of the pineal organ to the habenular commissure. At the proximal end of the stalk, some axons become myelinated. In the stalk, the axons intermingle with pinealocyte processes containing synaptic ribbons. The synaptic ribbons are in contact with (1) vesicles with a diameter of 300 Å; (2) 300 Å diameter vesicles and 800–1,200 Å diameter dense-core granules; or (3) the dense-core granules only. Dense-core granules are also present in pinealocytes with 9+0 type cilia. These results suggest that sensory and secretory structures are present in the same pineal cell type. Furthermore, “conventional” synapses are present between receptor and nerve cells: The presynaptic fibers have the same structure as the fibers containing synaptic ribbons. The numbers of microfibrils and microtubules vary among postsynaptic fibers (dendrites), the pinealocyte processes, and the neurites. Thus it is difficult to obtain an exact count of the number of axons running to the brain. Efferent sympathetic nerve fibers enter the pineal organ associated with the connective tissue surrounding blood vessels. The fibers show granules of 300–500 Å diameter or 800–1,200 Å diameter. After nialamide injection, both types of granules contain a dense core. Microspectrographically serotonin and noradrenaline are demonstrated in the sympathetic nerve fibers. There is no evidence found in the material of this study to suggest that sympathetic nerve fibers perforate the basement membrane and enter the parenchymal cell complexes of the pineal organ. Pinealocyte processes and sympathetic nerve fibers often show a very similar ultrastructural pattern. The role of the avian pineal organ in photo-neuro-endocrine regulation is discussed.
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