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  • 1970-1974  (577)
  • 1890-1899
  • Physical Chemistry  (289)
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  • 101
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 15-28 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The oxidation of inositol by quinquevalent vandadium in acid medium is a first-order reaction both in vanadium (V) and inositol. The stoichiometry of the reaction is consistent with the use of two equivalents of vanadium (V) per mole of inositol with the formation of one mole of inosose. The reaction is catalyzed both by sulfuric and perchloric acid, but the rate is faster in sulfuric acid than in perchloric acid. In 1M-6M perchloric acid solutions the reaction has shown a variable order in H+, but in solutions of 2M-5M sulfuric and perchloric acid of constant ionic strength, the rate has a linear dependence on [H+]2. There is also a linear correlation between the rate and bisulfate ions in sulfuric acid at constant hydrogen ion concentration. The energy of activation is found to be 19 kcal/mole and a negative entropy value of - 14 e.u. A suitable mechanism, consistent with the kinetics in 2M-5M acid solutions, is suggested and the values of various rate constants are evaluated.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 102
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Very strong laser emission at 5 μm was detected when SO2 and CHBr3 were flash photolyzed in the vacuum ultraviolet (λ ≥ 165 nm) in the presence of a large amount of diluent (SF6, He, or Ar). About 110 vibration-rotation transitions ranging from Δv = 18 → 17 to 3 → 2, except 16 → 15, were identified. The primary reactions leading to the CO stimulated emission are as follows: The product analysis results and the variation of laser intensity with flash energy and SO concentration indicate that the following side reactions are also occurring. Addition of a small amount of O2 enhances the laser output by both eliminating these side reactions and simultaneously producing vibrationally excited CO via reaction (8), which has been previously shown to generate CO stimulated emission. The effects of various reactive (NO and H2) and inert (He, Ar, SF6, CO, N2, N2O, and CO2) gases have been examined. All additives (P ≤ 20 torr), except NO and H2, increase the total laser output. N2O enhances the power most efficiently, whereas CO, N2, and CO2 are less effective and have similar efficiencies. The enhancement of the laser intensity by these near-resonant gases is ascribed to the depletion of CO population at lower levels which thus increases the rates cascading from higher levels. NO and H2 quench the laser output by chemically reducing the concentration of the CH radical.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 103
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 61-75 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A kinetic study of lead atoms in the spin orbit states, Pb(63P1) and Pb Pb(63P2), 0.969 and 1.320 eV, respectively, above the 63P0 ground state, has been carried out by atomic absorption spectroscopy. The electronically excited lead atoms were generated by the pulsed irradiation of lead tetraethyl and monitored photoelectrically by time-resolved attenuation of resonance radiation. The decay of the two atomic states has been studied in the presence of He, Ar, H2, D2, N2, O2, CO, NO, CO2, N2O, CH4, C2H4, C2H2 CF4, SF6, and PbEt4, and rate constants for the collisional quenching by these gases are reported. The resulting data are compared with those for the deactivation of other atomic spin orbit states of comparable energy. In general, the higher energy state, Pb(63P2), is found to be deactivated more rapidly. It would appear that the magnitude of the electronic energy to be transferred on collision governs the rates of quenching, at least where a weak interaction potential is involved, and that for most gases, deactivation of Pb(63P2) proceeds via Pb(63P1).
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 104
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The preparation and characterization of the iron(II) complex of the hexadentate Schiff base ligand NN‴-bis-[α-(2-pyridyl)benzylidene]triethylenetetramine are reported. Kinetic patterns and rate constants for aquation of this complex, and for its reactions with hydroxide, cyanide, and peroxodisulphate have been determined. Activation parameters for the reaction with cyanide, in aqueous solution, are ΔH
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 105
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 169-228 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Methods are discussed for the production and detection of the hydroperoxyl radical for use in gas phase kinetic studies. Rate constants for gas phase reactions of the hydroperoxyl radical with itself, H2, H2O, CO, NO, SO2, O3, C2H6, C3H8, i-and n-C4H10, C2H4, i-C4H8, HCHO, C2H5CHO, n-C3H7CHO, Br, O, OH, and H are critically evaluated. Recommended or estimated rate constant expressions with associated error limits are given applicable over specified temperature ranges (normally 300-1000°K). The reactivity of HO2 compared with OH, O, H, F, Cl, Br, CH3, and CH3O is presented in tabular form and the implications for atmospheric chemistry are discussed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 106
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 417-428 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the reaction between ozone and allene (A) were studied in the range of 226 to 325°K in the gas phase. Initial O3 pressures varied from 0.01 to 0.7 torr and allene pressures varied from 0.05 to 6 torr. At the higher initial O3 pressures the most important product was O2 followed by CO, H2O, CO2, and C2H4. Oxygen balances averaging about 110% were obtained, which implies that no important oxygenated products were missed. However, carbon balances were only about 50% and hydrogen balances were even less, so that unidentified hydrocarbons were presumably formed. The rate law found was - d[O3]/dt = k1[O3][A] + k2a[O3]2[A]/[O3]0 where log k1(M-1sec-1) = 6.0 ± 0.7 - (5500±1000)/2.30RT and log k2a(M-1sec-1) = 6.9 ± 0.7 - (6200 ± 800/2.30RT). A mechanism is proposed which accounts for the rate law and the observed stoichiometry of O2 formed-O3 used. This involves a heterogeneous catalyzed decomposition of O3. The rate constant k1 is identified with the primary addition reaction A + O3 → AO3, and this rate constant is compared with those from other O3 addition reactions.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 107
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 309-321 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The complexes PdCl42-, PdCl3(H2O)-, and PdCl3(Ac)2-, in rapid equilibrium with each other under the adopted experimental conditions, react with ethylenediamine according to the experimental rate law \documentclass{article}\pagestyle{empty}\begin{document}$$ k_{{\rm obs}} = \left\{ {\frac{k}{{\left[{{\rm H}^{\rm + } } \right]}} + \frac{{k'}}{{\left[{{\rm H}^{\rm + } } \right]\left[{{\rm Cl}^{\rm - } } \right]}} + \frac{{k''\left[{{\rm Ac}^{\rm - } } \right]}}{{\left[{{\rm H}^{\rm + } } \right]\left[{{\rm Cl}^{\rm - } } \right]}}} \right\}\left[{{\rm en}} \right]_{{\rm total}}$$\end{document} A reaction scheme is proposed involving the reaction of enH+ with each of the above species, and the specific rate constants are computed. The activation parameters are given.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 108
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 457-466 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Activation energies for substitution reactions of the type AC + B → A + CB, occurring in polar media and characterized by an abrupt change of the term along two coordinates have been calculated within the framework of the quantum-mechanical theory of chemical reactions. In the case of nonadiabatic processes, the transmission coefficient and activation energy for these reactions are expressed in terms of characteristic parameters of the medium (reorganization energy, effective frequency of solvent fluctuation polarization) and the potential energy curves for intermolecular interactions between the reactants (AC and B) and between the products (A and BC).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 109
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 481-492 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The photolysis of azocyclohexane, carbon tetrachloride, and cyclohexane at 360 nm has been investigated over a wide temperature range. At moderate temperatures a chain reaction ensues from which the following approximate rate constants could be determined assuming 2CCl3. → C2Cl6, k5 = 109.7 (303-673K): The really striking feature of the results is that they show that termination in bicyclohexyl [reaction (7)] is extremely slow: The root-mean-square rule for estimating the cross-combination rate is also followed.The photolysis of carbon tetrachloride and cyclohexane at 250 nm has also been investigated. The reaction is complicated by the occurrence of two concurrent photolytic processes, the main one yielding trichloromethyl radicals and chlorine atoms, and the subsidiary one yielding dichlorocarbene and molecular chlorine. Nonetheless the results from this reaction can be interpreted in the medium temperature range 360-430K, where long chains are present, in terms of the rate constants derived from the azocyclohexane system.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 110
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 531-543 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The effect of reactant self-heating or cooling upon rate data is considered, and three approaches to the problem of obtaining valid kinetic parameters are described in detail. A comparison of these approaches emphasises the need to assess and allow for thermal effects during the initial planning of kinetic experiments if satisfactory results are to be acquired. An integrated rate expression is given for use with nonisothermal data, and is used to provide correction factors for rate constants which have been derived without allowance for thermal effects.
    Zusätzliches Material: 6 Tab.
    Materialart: Digitale Medien
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  • 111
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 587-595 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the decay of hydroxyl radicals in the presence of excess acetylene were studied at pressures in the vicinity of 1 torr and at ambient temperature in a tubular discharge-flow reactor. Hydroxyl radicals were produced by the reaction of atomic hydrogen with nitrogen dioxide, H + NO2 → OH + NO. The concentration of hydroxyl was followed by line absorption photometry at 308.939 nm and 308.328 nm. Second-order rate coeffcients were determined in two sets of experiments. The initial concentration ratio [C2H2]0/[OH]0 was in the range of 2.3 to 13.2 in the first set, and 14 to 125 (owing to greater hydroxyl detection sensitivity) in the second set. Values of the second-order rate coefficient obtained were nk5 = (2.9 ± 0.3) × 10-13 cm3/molec-sec in the first set, and nk5 = (2.1 ± 0.6) × 10-13 cm3/molec-sec in the second set, where n is the stoichiometric coefficient of OH. A value of the bimolecular rate constant k5 = (2.0 ± 0.6) × 10-13 cm/molec-sec is consistent with both sets of data, as well as an earlier determination.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 112
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 113
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 663-685 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the reversible reaction \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm H}_3 {\rm AsO}_3 + {\rm I}_{3^-} + {\rm H}_2 {\rm O}\rightleftharpoons{\rm H}_3 {\rm AsO}_4 + 2{\rm H}^+ + 3{\rm I}^- $$\end{document} have been studied spectrophotometrically in acid solution under conditions in which both the forward and reverse reactions go to virtual completionand in which the reaction comes to a practical equlibrium. The rates of theforward (Rf) and reverse (Rr) reactions are given by \documentclass{article}\pagestyle{empty}\begin{document}$$R_f = \{f + g/[\rm H^+] + h/[\rm H^+]^2\} [\rm H_3 {\rm AsO}_3][I_{3^-}]/[I^-]^2 $$ $$ R_r = \{u[\rm H^+] + \upsilon [\rm H^+]^2\} [{\rm H}_3 {AsO}_4][I^-] $$\end{document} where f, g, h, u, and v have the values (4 ± 1) × 10-5 mole/1.·s, (4.2 ± 0.2) × 10-5 mole2/1.2·s, (5.0 · 0.3) × 10-7 mole3/1.3·s, (1.1 ± 0.1) × 10-3 1.2/mole2·s, and (3.7 ± 0.2) × 10-3 1.3/mole3·s at 298.2°K and at an ionic strength of 2.00M maintained by adding sodium chloride. The stoichiometric equilibrium constant under similar conditions is 0.022 ± 0.003. Differentvalues of these parameters were obtained when sodium perchlorate and sodiumnitrate were used to control ionic strength.The results are compared with those from previous reports and a mechanism is proposed based upon an initial rapid equilibrium \documentclass{article}\pagestyle{empty}\begin{document}$${\rm H}_3 {\rm AsO}_3 + {\rm I}_2 \rightleftharpoons{\rm H}_3 {\rm AsO}_3 {\rm I}^ + + {\rm I}^ -$$\end{document} followed by a rate-determining attack of water upon H3AsO3I+, H2AsO3I, and HAsO3I-.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 114
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 725-739 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reactions of ozone with simple olefins have been studied between 6 and 800 mtorr total pressure in a 220-m3 reactor. Rate constants for the removal of ozone by an excess of olefin in the presence of 150 mtorr oxygen were determined over the temperature range 280 to 360° K by continuous optical absorption measurements at 2537 Å. The technique was tested by measuring the rate constants k1 and k2 of the reactions (1) NO + O3 → NO2 + O2 and (2) NO2 + O3 rarr; NO3 + O2 which are known from the literature. The results for NO, NO2, C2H4, C3H6, 2-butene (mixture of the isomers), 1,3→butadiene, isobutene, and 1,1 -difluoro-ethylene are 1.7 × 10-1 4 (290°K), 3.24 × 10-17 (289°K), 1.2 × 10-1 4 exp (-4.95 ± 0.20/RT), 1.1 × 10-1 4 exp (-3.91 ± 0.20/RT), 0.94 × 10-1 4 exp ( -2.28 ± 0.15/RT), 5.45 ± 10-1 4 exp ( -5.33 ± 0.20/RT), 1.8 ×10-17 (283°K), and 8 × 10-20 cm3/molecule ·s(290°K). Productformation from the ozone-propylene reaction was studied by a mass spectrometric technique. The stoichiometry of the reaction is near unity in the presence of molecular oxygen.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 115
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 773-776 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 116
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 801-811 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The effect of added nucleophiles (methanol and 1,4-butanediol) on the steady-state kinetics of α-chymotryptic hydrolysis of a series of N-acetyl-L-amino acid methyl esters, R-CH(NHCOCH3)C(O)OCH3, has been studied. As a result, the rate and equilibrium constants of the ‘elementary’ steps of the enzyme process have been determined.It has also been demonstrated how the free energy-reaction coordinate profile changes if the structure (the size of the hydrocarbon chain) of the ‘chemically inert’ substrate fragment R is varied. The effects observed can be described by the following equation: where ΔGs and ΔGa are the free energies of formation of metastable intermediates, i.e., the enzyme-substrate complex and the acylenzyme, respectively, ΔG2≠ and ΔG3≠ are the free energies of activation for the chemical steps, i.e., enzyme acylation and acylenzyme hydrolysis, respectively; and ΔGtrans(R) is the free energy of transfer of substrate group R from water into a nonaqueous solvent.To explain the results obtained, a mechanism for enzyme-substrate interaction is suggested according to which the potential free energy of sorption of substrate group R on the enzyme is 2 ΔGtrans(R). Such a high gain in the free energy of hydrophobic interaction may only be realized if (a) in the free enzyme the sorption region has a thermodynamically unfavorable contact with the aqueous medium, and (b) water is forced out of the active center as a result of the hydrophobic interaction of substrate group R with the enzyme. Such a model is in agreement with the published x-ray data on the structure of the crystalline enzyme.The kinetic experiment has proved that not all the potential free energy of sorption is realized as binding force. Thus the true free energy of the binding of substrate group R with the protein does not exceed half the maximum value, both in the enzyme-substrate complex and acylenzyme.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 117
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 787-800 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetic equations for an 81-reaction model of a photochemical smog chamber have been solved using a complete numerical integration as well as a quasi-steady-state approximation (QSSA) procedure. The two sets of results differ markedly in their prediction of experimentally significant factors such as the hydrocarbon depletion rate and the ozone and (NO)x peaking times. The sources of the discrepancy are traced to the fact that the assumed steady-state conditions were not satisfied, leading to errors in the concentrations of intermediate radicals which in turn affect critical rates in the reaction model.The occurrence of such discrepancies in various types of reaction models, and with different QSSA strategies, is discussed, and it is concluded that the extent of such errors in QSSA calculations cannot be reliably predicted. Their impact on conclusions regarding reaction mechanisms and rate constants can surpass uncertainties in experimental data; conversely the credibility of predictions derived through QSSA calculations becomes highly suspect. Since recently devloped methods for complete numerical integration of systems of kinetic equations are now available, it is recommended that these be adopted in future work, and that the use of QSSA be abandoned.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 118
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 899-920 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Singlet methylene was reacted with cyclopentadiene to give chemically activated bicyclo[3.1.0]hex-2-ene (BCH). The rate of isomerization of BCH to 1,4-cyclohexadiene, 1,3-cyclohexadiene, cis-1,3,5-hexatriene, and l-methylcyclopentadiene is compared with calculated rate constants using the RRKM theory and measured or estimated thermal Arrhenius parameters. Subsequent isomerizations of the C6H8 products are also measured and calculated. These include 1,4-cyclohexadiene to benzene and the reversible reactions between 1,3-cyclohexadiene, cis-1,3,5-hexatriene, and trans-1,3,5-hexatriene. The results provide new data for several of these reactions which have not been observed in thermal studies. Agreement between the observed and calculated rates using the strong collision assumption is satisfactory except for the trans-1,3,5-hexatriene to cis-1,3,5-hexatriene reaction.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 119
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 741-751 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Technical improvements have been made in the application of the phase shift method, recently developed and used in this laboratory to measure the absolute values of the rate constants of the reactions of O(3P) atoms with ethylene, propylene, 1-butene, and isobutene. More accurate rate constants have now been obtained for these olefins and themeasurements have been also extended to three additional olefins (cis-2-butene, trimethylethylene, and tetramethylene).The mean least squares values of the rate constants of the reactions of O(3P) with olefins at 26°C, expressed as k2 × 10-9 (1./mole2·sec), and their standard deviations are ethylene 0.43 ±0.05, propelene 2.02 ± 0.17, 1-butene 2.40 ± 0.32, isobutene 9.85 ± 1.34, cis-2-butene 9.00 ± 1.76, trimethylethylene 31.1 ± 3.0, and tetramethylethylene 44.4 ± 4.1. A Value of (5.78 ± 0.08) × 1010l.2/mole2·sec was obtained for the rate constant of the reaction O(3P) + NO + M, with M = N2O. Where comparison with the absolute rate constants in the literature is possible, agreement is very good, especiallywith some recent absolute values obtained by entirely different experimental techniques. Consistency with the relative rate constant of the O(3P) reactions with olefins previously determined in this laboratory, is excellent.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 120
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 877-885 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The heats of formation of C3 and C4 alkyl nitrites (RONO) have been determined via their heats of combustion by bomb calorimetry, thereby providing a complete set of values of ΔHºf for C1-C4 alkyl nitrites. The experimental values are in excellent agreement with values derived from group additivity rules. For branched compounds these calculations involve corrections for gauche interactions. In these cases, the gauche interactions are reflected in the activation energies E1 determined by recent kinetic studies, required for breaking the RO-NO bond. The heats of formation of the alkoxy radicals involved together with ΔHºf(NO) = 21.6 kcal/mole leads to the result D(RO-NO) = 41.5 ± 1 kcal/mole. The concordance between D(thermochemical) and D(kinetic), unlike previous kinetic studies, implies that E2 = 0 ± 1 kcal/mole.
    Zusätzliches Material: 10 Tab.
    Materialart: Digitale Medien
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  • 121
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 29-37 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The following net processes occur in a system containing chlorine and hydrogen bromide: \documentclass{article}\pagestyle{empty}\begin{document}$$(1)\begin{array}{*{20}c} {} & {} \\ \end{array}{\rm Cl}_{\rm 2} + {\rm HB}r \to {\rm BrCl + HCl}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$(2)\begin{array}{*{20}c} {} & {} \\ \end{array}{\rm BrCl + HB}r \to {\rm Br}_{\rm 2} {\rm + HCl}$$\end{document} These reactions have been followed spectrophotometrically in a gas phase stopped flow apparatus. The first two reactions are strongly surface catalyzed on untreated glass or quartz, but are much slower if the cell surface has been covered with silicone and photochlorinated. Rates in such systems are first order in each reactant, and comparable limiting rate constants have been obtained in cells with different methods of preparing the surfaces and with different surface-to-volume ratios. These experimental rate constants must be equal to or greater than those of the homogeneous bimolecular reactions. Then limiting rate constants at 35°C in liters per mole per second are k1 ≤ 0.8, k 2 ≤ 15, and k3 ≤ 0.04. Reactions of HI with Cl2, Br2, and ICl are all much faster than reaction (2). These observations and those of other diatomic molecule reactions can be rationalized if halogen and hydrogen halide molecules react through a transition state in which the hydrogen atom is near the center of a triangle of three halogen atoms.
    Zusätzliches Material: 3 Tab.
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  • 122
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 89-102 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Flash photolysis of 2,4,6-trinitrotoluene solutions (TNT) indicates a photochemically induced isomerization leading to the aci-quinoid isomer with an absorption maximum at 460 nm in nonpolar solvents, or the conjugate base of the aci-quinoid isomer with absorption maxima at 500, 540, and 630 nm in polar solvents. Both species, the quinoid isomer and the conjugate base, have transient existence and their identification was based on detailed spectroscopic and kinetic studies presented here. The magnitude of the negative charge on the transient conjugate base was determined with salt effect experiments and found to be equal to unity.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 123
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 103-110 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the alkaline hydrolysis of five diol monoesters and related esters in aqueous DMSO, aqueous acetone, and aqueous ethanol are reported. A novel solvent dependency of the reactivity pattern of the various esters is noticed. The results are explained on the basis of an internal stabilization of the transition state and the influences of the various solvent systems on such transition states. It is suggested that such dipolar aprotic-protic solvent influences on reaction rates can be used as a criterion in the assessment of anchimeric assistance in such reactions.
    Zusätzliches Material: 7 Tab.
    Materialart: Digitale Medien
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  • 124
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 111-123 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The exponential relaxation of CH3, produced by the reaction O + C2H4 → CH3 + HCO, to its steady-state concentration was quantitatively monitored after the reactants were mixed. The relaxation profiles yield the rate constant of the reaction O + CH3 → H2CO + H equal to (1.85 ± 0.28) × 10-10 cm3/molecule-sec at 300°K. Ancillary experiments yielded values for the rate constant for the reaction of O atoms with C2H4 at 300°K, the average of which is 7.7 × 10-12 cm3/molecule-sec. The experimental technique, which employs a fast-flow reactor coupled to a photoionization mass spectrometer, is described in detail and its potential discussed.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 125
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 126
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 245-256 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of N-phenylphthalamic acid and of N-phenylphthalimide hydrolysis in aqueous solutions of sulfuric acid has been studied. A reaction mechanism is proposed implying that unreactive forms of the reactant appear by protonization of the amide bond at the carbonyl oxygen and by dissociation of the o-carboxyl group (N-phenylphthalamic acid). Attack of the nonprotonized amide bond by the hydroxonium ion is suggested to be the rate-limiting step.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 127
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 279-290 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Oxidation of tetralin in the presence of tert-butyl hydroperoxide and tetralyl hydroperoxide, initiated with azobisisobutyronitrile, was studied at 60°C in order to examine the complications involved in the hydroperoxide method devised by Howard and Ingold. From literature data on absolute rate constants and our rates of oxidation, cross termination rate constants and contributions of each elementary propagation and termination step were computed. It was confirmed that this method was quite useful in determining the cross propagation rate constant, but it was also demonstrated that the rate of oxidation should be measured at very low conversion and with quite high concentrations of hydroperoxide, especially when the peroxy radical derived from the added hydroperoxide has a much lower termination rate constant than that from the oxidizing substrate.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 128
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 129
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 297-308 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate constant for the reaction I(2P1/2) + CH3I → I2 + CH3 has been reevaluated taking into account both collisional deactivation of excited iodine atoms and loss of I2 by I2 + CH3 → I + CH3I. The reevaluation is based upon data obtained (R. T. Meyer), J. Chem. Phys., 46, 4146 (1967) from the flash photolysis of CH3I using time-resolved mass spectrometry to measure the rate of I2 formation. Computer simulations of the complete kinetic system and a closed-form solution of a simplified set of the differential equations yielded a value of 6(± 4) × 106 1./mole-sec for the excited iodine atom reaction in the temperature region of 316 to 447 K. A slight temperature dependence was observed, but an activation energy could not be evaluated quantitatively due to the small temperature range studied. An upper limit for the collisional deactivation of I(2P1/2) with CH3I was also determined (2.4 × 107 1./mole-sec).
    Zusätzliches Material: 3 Ill.
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  • 130
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 337-357 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Absolute values of the rate constants for the reaction of hydrogen atoms with cyclic olefins in the gas phase have been measured in a discharge-flow system under 3.5, 16, and 22 torr Ar at 23°C. The attenuation of hydrogen atom concentration in the reaction tube in the presence of a large excess of olefin was measured with an ESR spectrometer, and the products were analyzed by gas chromatography. Cyclic C6 hydrocarbons were the only significant products obtained when the hydrogen atom concentration was 2.6 × 10-10 mole/1., the olefin concentration was in the range of 9 to 22 × 10-8 mole/1., and the pressure was 16 torr Ar. The values for the rate constants for reaction with cyclohexadiene-1,3, cyclohexadiene-1,4, and cyclohexene are, respectively, (9 ± 2) × 108, (12 ± 1) × 108, and (6 ± 1) × 108 l./mole-sec, and they are not changed significantly by a sixfold change in total pressure. The fraction of the total interaction that proceeds by addition is 84% in the cyclohexadiene-1,3 system, but only 18% in the cyclohexadiene-1,4 system, and the cyclohexadienyl radical is therefore the dominant radical species in the latter system. The pattern of interaction between the hydrogen atom and the cyclohexadienyl radical was determined, and comprises 65% of disproportionation, and 13% and 23% of combination to yield cyclohexadiene-1,3 and cyclohexadiene-1,4, respectively. These results are consistent with the general patterns of reactivity emerging from studies of the reactions between free radicals and olefins in related systems.
    Zusätzliches Material: 3 Ill.
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  • 131
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 395-400 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Different possible mechanisms for the gas phase reaction of formation of bromine chloride from bromine and chlorine are discussed. The rate of the reaction has been deduced from photometric measurements in conventional static reactors of surface-to-volume ratio ranging between 0.6 and 3 cm-1, at temperatures between 51 and 113°C. Experimental data show that (1) the observed reaction is predominantly heterogeneous, and (2) the homogeneous reaction must proceed by an atomic chain mechanism initiated by Br atoms.
    Zusätzliches Material: 1 Ill.
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  • 132
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 359-370 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The four species in the title were decomposed under VLPP conditions at temperatures in the vicinity of 1100°K. Three model transition states were constructed that fit the low-pressure data thus obtained and that also yield (1) E298 = ΔE298; (2) E1100 = ΔE1100; (3) log A1100 = 16.4 per C-C bond broken. The predictions of these models as to values of the high-pressure rate constants for bond scission and the reverse rate constants (radical combination) are compared with existing data.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 133
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 437-441 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate constants of liquid-phase hydrogen abstraction by chlorine atoms from 1,2-C2H4Cl2 relative to those of addition to C2HCl3 and to C2Cl4 and to that of hydrogen abstraction from cyclohexane have been measured between 250 and 345°K. Assuming a zero activation energy for the addition reactions permits one to calculate the corresponding values for the liquid-phase hydrogen abstraction from the chlorinated ethanes. These values are discussed and compared with the gas-phase data.
    Zusätzliches Material: 2 Tab.
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  • 134
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 135
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 553-565 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of O(3P), prepared from the Hg photosensitization of N2O, with C2HCl3 was studied at 25°C. The products of the reaction in the absence of O2 were CO, CHCl3, and polymer (as well as N2 from the N2O). The quantum yields of CO and CHCl3 were 0.23 ± 0.01 and 0.14 ± 0.05, is respectively independent of reaction conditions. The reaction mechanism is with k14a/k14 = 0.23, where k14a + k14b. Most of the HCl and CCl2 combine to form CHCl3, but some other products must also be formed to account for the difference in the CO and CHCl3 quantum yields. The C2HCl3O* adduct polymerizes without involving additional C2HCl3 molecules, since the quantum yield of C2HCl3 disappearance, —Φ{C2HCl3}, was about 1.0 at high values of [N2O]/[C2HCl3]. The rate coefficient for the reaction of O(3P) with C2HCl3 is 0.10 that for the reaction of O(3P) with C2F4.In the presence of O2 the free radical chain oxidation occurs because of the reaction The main product is CHCl2CCl(O) with smaller amounts of CO and CCl2O, and some CO2. The chain lengths were long and values of — Φ {C2HCl3} up to 90 were observed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 136
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 617-630 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reactions \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {(1)} {{\rm O + HNO}_3 \to {\rm products}}\\ {(2)} {{\rm H + HNO}_{\rm 3} \to {\rm products}} \end{array}$$\end{document} have been studied in a discharge-flow system. Kinetic studies were made using resonance fluorescence for the measurement of atom concentrations. Based on the rates of atom loss, the following upper limits were obtained for the rate constants: \documentclass{article}\pagestyle{empty}\begin{document}$$ k_1 \le 3 \times 10^{ - 17} {\rm cm}^{\rm 3} /{\rm molec - sec} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k_1 \le 2 \times 10^{ - 15} {\rm cm}^{\rm 3} /{\rm molec - sec} $$\end{document} Observed reaction in the H—HNO3 system is at least partially due to an autocatalytic chain removal of both reactants. Diagnostic tests have suggested that OH, NO2, and NO3 are the chain carriers.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 137
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 631-641 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The thermal decomposition of t-butylmethyl ether has been studied using the VLPP technique. The recommended Arrhenius parameters for the molecular elimination, reaction (1), are A(800°K) = 101 3, 9 sec-1 and Ea (800°K) = 59.0 ± 1.0 kcal/mole. No radical reactions occur under the conditions used. These parameters are in good agreement with earlier experimental work and with theoretical estimates of both A and E.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 138
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A step perturbation (concentration-jump or solvent-jump) relaxation method is described for studying the rates of fast reactions, using nontransient observation in a steadystate flow system. Therelaxation time is determined from a single measurement of an integrated relaxation amplitude. Remeasurement of the rate of dimerization of aqueous rhodamine B is reported.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 139
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 713-724 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Rate constants and activation parameters are reported for the decarboxylation of malonic acid in seven normal alkanols (butanol-l to decanol-l inclusive). It is found that the enthalpy of activation of the reaction is a linear function of the number of carbon atoms in the hydrocarbon chain of tthe solvent, expressed by the equation: ΔH≠ = -600n + 30,000, where n is thenumber of carbon atoms in the chain. Also an equation is developed relatingthe rate constant for the decarboxylation of malonic acid in normal alkanols to n (the number of carbon atoms in the chain): log K = 10.854283 - 0.3212674n + (131.136876n - 6556.5438)/T + log T. With the aid of this equation rate constants may be calulated for the decarboxylationof malonic acid in any alcohol at any temperature which agree with experimental values to within the limit of error of the experiments. A comparison of the data obtained in the present research for the decarboxylation of malonic acid in normal alkanols with previously reported data for the reaction in amines indicates that for reaction taking place in alcohols the transition state probably contains two molecules of solvent but only one for the reaction in amines.
    Zusätzliches Material: 5 Ill.
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  • 140
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 693-711 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A low-temperature matrix isolation method has been developed which makes possible the isolation and detection of HO2 radicalsfrom a gas-phase radical chain-reaction system containing atomic H, O and OH radicals as well. The formation of HO2 radicals is demonstrated in the rarified hydrogen flame. The same radicals are observed to exist during the slow oxidation reaction of hydrogen between the second and third inflammation limitsThe kinetics of accumulation of HO2, H2O2, and H2O has been studied as a function of total pressure, composition of reacting mixtures, temperature, and diameter and the treatmentof the surface of the reaction vessel. It has been established that in a reactor treated with boric acid, the concentration of HO2 radicalsis in the order of 101 2-101 4 particles/cm3. The kinetic relationship obtained confirms the necessity of including the following step in the mechanism of slow oxidation of hydrogen: \documentclass{article}\pagestyle{empty}\begin{document}$${\rm HO}_2 {\rm + }\;{\rm HO}_{{\rm 2 }} = {\rm H}_{\rm 2} {\rm O}_{\rm 2} {\rm + O}_{\rm 2} $$\end{document}For a quantitative description of the experimental results, calculationsof the complete mechanism of the slow reaction are performed by computer methods. The values of the rate constants of the elementary reactions that enter into the mechanism proposed were taken from published data. Some of them were varied by small intervals to give a better agreement with experimental values. The agreement justifies the mechanism proposed for the experimental conditions employed.
    Zusätzliches Material: 10 Ill.
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  • 141
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 763-771 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The homogeneous pyrolysis of 2-butene subjected to shock heating was studied in the limit of high pressures by a relative rate technique. Over the temperature range of 1150-1325°K nearly equal amounts of methane, propylene, and butadiene were formed starting with either the cis- or trans-2-butene, while isomerization remained far from equilibrium. The results are consistent with a simple free radical mechanism for which we find \documentclass{article}\pagestyle{empty}\begin{document}$$ k^\infty [{\rm C}_4 {\rm H}_8 \mathop \rightarrow\limits_{cis} {\rm CH}_3 + {\rm C}_3{\rm H}_5] = 10^{16} \exp (-80,000/RT)\sec^{-1} $$\end{document} as the initial rate-limiting step.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 142
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 829-848 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The chemical reactions of SO2(3B1) molecules with cis- and trans-2-butene have been studied in gaseous mixtures at 25°C by excitation of SO2 within the SO2(3B1) → SO2(+, 1A1) ‘forbidden’ band using 3500-4100-Å light. The initial quatum yields of olefin isomerization were determined as a function of the [SO2]/[2-butene] ratio and added gases, He and O2. The kinetic treatment of these data suggests that there is formed in the SO2(3B1) quenching step with either cis- or trans-2-butene, some common intermediate, probably a triplet addition complex between SO- and olefin. It decomposes very rapidly to form the 2-butene isomers in the ratio [trans-2-butene]/[cis-2-butene] = 1.8. In another series of experiments SO2 was excited using a 3630 ± 1-Å laser pulse of short duration, and the SO2(3B1) quenching rate constants with the 2-butenes were determined from the SO2(3B1) lifetime measurements. The rate constants at 21°C are (1.29 ± 0.18) × 1011 and (1.22 ± 0.15) × 1011 l/mole·sec with cis-2-butene and trans-2-butene, respectively, as the quencher molecule. Within the experimental error these quenching constants equal those derived from the quantum yield data. Thus the rate-determining step in the isomerization reaction is suggested to be the quenching reaction, presumably the formation of the triplet SO2-2-butene addition complex. In a third series of experiments using light scattering measurements, it was found that the aerosol formation probably originates largely from SO3 and H2SO4 mist formed following the reaction SO2(3B1) + SO2 → SO3 + SO(3Σ-). Aerosol formation from photochemically excited SO2-olefin interaction is probably unimportant in these systems and must be unimportant in the atmosphere.
    Zusätzliches Material: 3 Ill.
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  • 143
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 887-891 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The decaying absorption of CH3 radicals at 216.4 nm has been followed over more than three half-lives using a photoelectric split-beam kinetic spectrometer. The rate constant for recombination kr was found to be (5.60 ± 0.76) × 10-11 cm3/molecule·s.
    Zusätzliches Material: 3 Ill.
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  • 144
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 875-876 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 145
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 893-897 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The thermal isomerization of 1,1-divinylcyclopropane has been investigated in the gas phase in the temperature range of 238 to 288°C and for pressures in the range of 4 to 12 torr. The isomerization to 1-vinylcyclopentene is homogeneous and kinetically first order and almost certainly unimolecular. The rate constants yield the Arrhenius equation \documentclass{article}\pagestyle{empty}\begin{document}$$\log {\rm }k({\rm s}^{ - 1} {\rm)} = 13.53 \pm 0.13 - (42.45 \pm 0.33{\rm \,kcal/mole})/RT\,{\rm In 10}$$\end{document} or \documentclass{article}\pagestyle{empty}\begin{document}$$\log {\rm }k({\rm s}^{ - 1} {\rm)} = 13.53 \pm 0.13 - (117.6 \pm 1.4{\rm \,kJ/mole})/RT\,{\rm In 10}$$\end{document} The assumption of a similar transition state for this isomerization with that of l-methyl-l-vinylcyclopropane leads to a value for an alkylpentadienyl radical stabilisation energy of 19.2 ± 1.6 kcal/mole (80.4 ± 6.7 kJ/mole), and this value is compared with other estimates.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 146
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 278 (1973), S. 425-430 
    ISSN: 1432-1912
    Schlagwort(e): Brocresine ; Diamine Oxidase ; Rat ; Plasma ; Liver ; Stomach ; Small Intestine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. In male rats DAO was found to be absent in plasma and liver, very low in gastric and high in the upper small intestinal mucosa. 2. Gastric mucosal DAO was completely abolished by 10−8 M Brocresine. In the small intestine inhibition of DAO by Brocresine was dose-dependent, with a concentration of 6.2×10−6 M producing a 50% inhibition of the enzyme. 3. Pretreatment of rats with 100 mg/kg Brocresine i.p. produced a 43% inhibition of DAO after 1 h and an insignificant inhibition by 20% after 4 h. 4. The results suggest that the histidine decarboxylase inhibitor Brocresine is not a very suitable tool for studying the physiological role of histamine by inhibiting its biosynthesis since it also interferes with the histamine catabolism.
    Materialart: Digitale Medien
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  • 147
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 279 (1973), S. 133-152 
    ISSN: 1432-1912
    Schlagwort(e): Intestinal Absorption ; Tritiated Water ; Urea ; Solvent Drag ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. Jejunal loops of anaesthetized rats were perfused with hypotonic, isotonic, and hypertonic buffered solutions containing tritiated water or 14C-labelled urea. The blood flow of the loop was maintained constant at an intermediate rate (0.8–0.9 ml min−1 g−1 wet tissue weight). The water net flux was determined by means of polyethylene glycol as nonabsorbable marker and amounted up to ±30 μl min−1 g−1 w. w. 2. A positive water net flux (directed towards the blood) increased the absorption rates (disappearance rate from the intestinal lumen, appearance rate in the intestinal venous blood) of tritiated water and urea by maximally 22 and 41%, a negative water net flux (directed towards the gut lumen) diminished it by 12 and 32%. 3. The data were analysed by means of a kinetic model with the water net flux as independent variable. The sieving coefficient ⧫=1-δ was 1.18±0.44 for tritiated water and 0.86±0.11 for urea at pH 6.2. The water net flux influenced the absorption of solutes by interaction within the membranes (solvent drag in a restricted sense) and by changing the volume of blood flowing in the capillaries near the epithelium. This last effect is large for the absorption of the rapidly absorbable tritiated water, but small for the absorption of urea which is absorbed ten-times slower. 4. The water net flux in the intestine depended linearly on the osmotic pressure difference between lumen and blood. The hydraulic permeability was 146–180 ml2 min−1 g−1 osm−1.
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  • 148
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 279 (1973), S. 153-172 
    ISSN: 1432-1912
    Schlagwort(e): Intestinal Blood Flow ; Intestinal Absorption ; 3-O-Methylglucose ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. Jejunal loops of anaesthetized rats were perfused (single pass perfusion and recirculation) with buffered solutions containing 3-O-methylglucose (3-OMG) in two concentrations: below (about 30 μM) and above (about 30 mM) blood glucose concentration. The blood flow, the appearance rate (in the intestinal venous blood) and the disappearance rate (from the intestinal lumen) were determined simultaneously, the accumulation in the gut wall at the end of the experiments. 2. At constant intermediate blood flow the appearance rate and disappearance rate decreased with time. A decrease of the blood flow rate from about 1.8 to about 0.3 ml min−1g−1 diminished the appearance and disappearance rate. An increase of blood flow from about 0.3 to about 1.9 ml min−1g−1 caused no increase of absorption; even a slight decrease was observed. 3. A kinetic analysis of the data showed that the different blood flow dependence of 3-OMG absorption in the experiments with increasing and decreasing blood flow can be explained sufficiently by a decrease of transport capacity with time, presumably due to an altered regional blood flow (decreased villous blood flow rate, unchanged total rate). A postischemic inhibition of 3-OMG absorption was of less importance. 4. The increase in perfusion rate from 0.1 (single pass perfusion) to 10 ml min−1 (recirculation) caused an increase of 3-OMG absorption and tissue accumulation.
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  • 149
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 280 (1973), S. 49-62 
    ISSN: 1432-1912
    Schlagwort(e): Corticotropin-Releasing Factor ; Corticoids ; Median Eminence ; Rat ; Histology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In 465 female Wistar rats the influence of an i.m. injection of various natural or synthetic corticoids on the augmentation of “Gomori-positive” granules in the outer layer of the median eminence following bilateral adrenalectomy has been investigated. While the augmentation of the granules is not impaired by progesterone it is inhibited or completely blocked, depending on the dose and the manner of application, by 11-desoxycorticosterone, corticosterone, cortisol, 9α-fluorocortisol, prednisolone, triamcinolone, dexamethasone and fluoroformylone. The doses necessary to suppress the augmentation of the granules correspond to those shown by other authors to be required for blocking ACTH-secretion. The inhibitory effect of the investigated corticoids on the augmentation of the granules is related to their antiphlogistic potency. The findings suggest that the amount of the “Gomori-positive” granules in the outer layer of the median eminence of the rat might be used as a parameter of the activity of the corticotropin-releasing factor.
    Materialart: Digitale Medien
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  • 150
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 277 (1973), S. 113-138 
    ISSN: 1432-1912
    Schlagwort(e): Intestinal Blood Flow ; Intestinal Absorption ; l- and d-phenylalanine ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. Jejunal loops of anaesthetized rats were perfused (single pass and recirculation) with buffered solutions containing l-phenylalanine (about 30 μM and 30 mM) and d-phenylalanine (about 30 μM). The blood flow, the disappearance rate (from the intestinal lumen) and the appearance rate (in the intestinal venous blood) were determined simultaneously, the accumulation in the gut wall at the end of the experiments. 2. At a constant intermediate blood flow the absorption of l- and d-phenylalanine decreased with time. A decrease of blood flow from about 1.6 to 0.25 ml min−1g−1 wet tissue weight diminished the appearance and the disappearance rate of both isomers. An increase of blood flow from 0.25 to 1.6 ml min−1g−1 caused no increase of absorption; on the contrary the appearance and disappearance rate decreased a little. The different dependence of absorption when decreasing and increasing the blood flow rate may be caused by a changed pattern of blood flow in the layers of the gut wall, i.e. the flow rate in the villi may be reduced while the flow rate in the entire wall remains unchanged. 3. In the single pass perfusion experiments the appearance rate of l-phenylalanine increased proportionally to the luminal concentration (30 μM and 30 mM), while the accumulation was relatively smaller at the high concentration. In the recirculation experiments the appearance rate and the accumulation of l-phenylalanine did not increase proportionally. 4. The increase in perfusion rate, from 0.1 (single pass perfusion) to 2–3 and 10 ml min−1 (recirculation), caused an increase of l-phenylalanine absorption and tissue accumulation. 5. At a luminal concentration of about 30 μM the appearance rates of l- and d-phenylalanine were equal, while the tissue accumulation was smaller for the d-isomer.
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  • 151
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 13 (1973), S. 113-129 
    ISSN: 1432-0827
    Schlagwort(e): Kinetics ; Growth ; Epiphyses ; Hypophysectomy ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé La largeur de la métaphyse tibiale, la zone indifférenciée, la zone sériée et les cellules en dégénerescence ont été observées chez des rats Sprague-Dawley normaux et hypophysectomisés. La production cellulaire de la métaphyse est déterminée sur la base de la croissance osseuse longitudinale déterminée par l'oxytétracycline et la taille des cellules en dégénérescence. La diminution de la croissance osseuse longitudinale, en fonction de l'augmentation de l'âge et après hypophysectomie, est due partiellement, à la diminution de production cellulaire et partiellement à une décroissance de la taille des cellules en dégénérescence dans la métaphyse. L'influence de la production cellulaire et de l'activité mitotique prédomine.
    Kurzfassung: Zusammenfassung Die Breite der proximalen Wachstumsplatte der Tibia, deren undifferenzierter und säulenförmiger Zone und die Größe der nahe bei der Metaphyse auftretenden degenerativen Zellen wurden in normalen und hypophysektomierten Sprague-Dawley-Ratten bestimmt. Die Zellproduktion in der Wachstumsplatte wurde aus dem longitudinalen Knochenwachstum berechnet, welches mittels Oxytetracyclin und der Größe der degenerativen Zellen bestimmt wurde. Es wurde festgestellt, daß die Abnahme des longitudinalen Knochenwachstums bei zunehmendem Alter und nach Hypophysektomie zum Teil einem Rückgang in der Zellproduktion, zum Teil einer Verminderung der Größe der degenerativen Zellen in der Wachstumsplatte zuzuschreiben ist. Der Einfluß der Zellproduktion, und somit der mitotischen Aktivität, herrscht vor.
    Notizen: Abstract The width of the proximal growth plate of the tibia, its undifferentiated and columnar zone and the size of the degenerative cell close to the metaphysis, were determined in normal and hypophysectomized Sprague-Dawley rats. The cell production in the growth plate was calculated from the longitudinal bone growth determined with oxytetracycline and the degenerative cell size. It was found that the decrease in longitudinal bone growth with increasing age and after hypophysectomy, is due partly to a decrease in cell production, and partly to a decrease in degenerative cell size in the growth plate. The influence of cell production and thus the mitotic activity predominates.
    Materialart: Digitale Medien
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  • 152
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 139 (1973), S. 119-126 
    ISSN: 1432-0568
    Schlagwort(e): Cleavage stages ; Egg-cylinder ; Mouse ; Rat ; Hydrolytic enzymes distribution ; Differentiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The time of appearance and the distribution of alkaline and acid phosphatase and nonspecific esterase was investigated in cleavage and early postimplantation stages of mouse and rat embryos. Alkaline and acid phosphatase appeared for the first time in 8-cell embryos. Activity of both enzymes grew progressively stronger to blastocyst stage. Acid phosphatase activity was revealed in the form of fine and coarse granules distributed evenly in the cytoplasm. Alkaline phosphatase was predominantly localized in plasma membranes. There was no difference in intensity of reaction between trophoblastic cells and the inner cell mass. After implantation acid phosphatase was localized in coarse granules in the apical portion of entodermal cells. With the appearance of mesoderm, the cells of embryonal entoderm became flattened and devoid of acid phosphatase activity which was restricted to cells of extraembryonic entoderm. The activity of nonspecific esterase was not detected in preimplantation stages. In postimplantation embryos it roughly corresponded to the activity of acid phosphatase. Alkaline phosphatase was localized in cell membranes of ectodermal cells. The mesodermal cells of mouse embryo displayed a somewhat weaker activity than ectodermal cells, while in the rat embryo the same layer remained completely nonreactive. Our findings on the distribution of the enzymes mentioned did not reveal any kind of polarity or bilateral symmetry in preimplantation stages. In postimplantation stages acid phosphatase and nonspecific esterase are probably bound to lysosomes and play an important role in embryonic nutrition. The absence of alkaline phosphatase from entodermal cells is somewhat puzzling and suggests that the process of molecular transport in those cells is most probably restricted to endocytosis. Our results suggest that all blastomeres are identical with respect to enzyme distribution and that the first signs of differentiation of enzyme content appear with the formation of germ layers.
    Materialart: Digitale Medien
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  • 153
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 140 (1973), S. 281-318 
    ISSN: 1432-0568
    Schlagwort(e): Central monoamine neurons ; Ontogeny ; Rat ; Fluorescence histochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The development of all monoamine-containing neuron systems in the rat brain throughout the last seven days of gestation, i.e. from the 15th day to term, crown rump length (CRL) 16 mm to 42 mm, has been followed using the Falck-Hillarp method for fluorescence histochemistry. Serial sagittal, horizontal and transverse sections through whole brains of fetuses from MAO-inhibited mothers have been carefully analyzed by fluorescence microscopy, and drawings of almost all sections depicting specific fluorescence have been collected from 10 of the 16 analyzed brains. Thus, all the 5-hydroxytryptamine (5-HT), dopamine (DA) and noradrenaline (NA) neuron systems have been mapped, both regarding the cell groups, the formation of axon pathways and the development of terminal plexuses in the whole brain prenatally. Together with a previous report (Olson and Seiger, 1972a) the present data have made it possible to determine the common origin of groups A1–A3, A4–A7, A8–A10, B1–B3 and B4–B9, respectively (nomenclature according to Dahlström and Fuxe, 1964). These findings and an estimation of the number of visible fluorescent cells in all monoamine cell complexes throughout the prenatal period of development have been summarized in a flow-chart. In the full-term fetus all monoamine neurons and their axon pathways, except for the hypothalamic cell groups, are very well developed. Thus, the new neuroanatomical data presented, in all probability hold true also for the adult state. A comprehension of the innervation course of neostriatum by DA nerve terminals from the 14th day of gestation to adult hood is given.
    Materialart: Digitale Medien
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  • 154
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 141 (1973), S. 125-150 
    ISSN: 1432-0568
    Schlagwort(e): Rat ; Columns ; Swirls ; Interneurons ; Projection neurons ; Subdivisions ; Morphology ; Golgi ; Nissl ; Axons ; Dendrites ; Cerebellum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The lateral nucleus in the rat is investigated with several variants of the rapid Golgi method and in Nissl preparations. The neurons are divided into two classes according to their size and the disposition of their axons. The smaller neurons or interneurons have cross sectional areas less than 180 μm2, and short axons that ramify in the vicinity of the cell bodies. Small neurons have also been seen on rare occasions with longer axons that may leave the nucleus. The larger cells (areas greater than 180 μm2) have long axons that leave the nucleus and emit short, beaded, recurrent collaterals. In the rostral and caudal poles of the lateral nucleus, the large projection neurons as well as the small neurons are multipolar with swirled dendritic arborizations. Neurons in the dorsal rim and ventral third of the nucleus have similar dispositions of their dendrites. In the central columnar zone, the projection neurons have dendrites that are arranged in columns directed diagonally across the body of the nucleus in the 4 to 10 o'clock direction in the right lateral nucleus and the 8 to 2 o'clock direction in the left nucleus. A collection of small neurons is generally found in the medial hilus zone. In each part of the lateral nucleus, the neurons are arranged in characteristic ways.
    Materialart: Digitale Medien
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  • 155
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 141 (1973), S. 275-288 
    ISSN: 1432-0568
    Schlagwort(e): Cerebral ventricles ; Perinatal period ; Subependymal cells ; Rat ; Light and electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Gehirne von 93 Ratten (letzte Embryonalwoche bis zum 30. postnatalen Tag) wurden licht- und elektronenmikroskopisch untersucht. Am Ende der zweiten Embryonalwoche treten im mittleren Teil des III. Ventrikels Zellen auf, deren Cytoplasma sich mit einer Perjodsäure-Bisulfit-Aldehydthionin-Methode blau anfärben läßt. Die blauen Zellen werden nach der Geburt auch an anderen Abschnitten des III. Ventrikels sowie am Aquaedukt und IV. Ventrikel ausschließlich in einer lockeren subependymalen Gliazone gefunden. Zwischen dem 14. und 17. Tag nimmt ihre Zahl ab, um den 22. postnatalen Tag sind die blauen Zellen völlig verschwunden. Gleichzeitig wird die subependymale Auflockerungszone dichter. Elektronenmikroskopisch werden die blauen Zellen als fortsatzreiche Elemente identifiziert, die viele Mitochondrien und unterschiedlich große Vacuolen und Cytosomen enthalten. Die Fortsätze umschließen subependymale Räume, die ein feinflockiges Material enthalten. Die Zellen werden als mikrogliäre Elemente angesehen, ihre Funktion mit dem Verschwinden der subependymalen Auflockerungszone in Verbindung gebracht.
    Notizen: Summary The brains of 93 rats (of between the last week of pregnancy up to the 30th postnatal day) were investigated by means of light and electron microscopy. At the end of the second week of pregnancy, subependymal cells, the cytoplasm of which is blue after staining with a periodic-acid-bisulfit-aldehydethionine-method, begin to appear in the middle part of the IIIrd ventricle. After birth, the blue cells can also be demonstrated in other parts of the IIIrd ventricle as well as in the wall of aquaeduct and the IVth ventricle. The cells are exclusively found in a loosely textured subependymal tissue. Between the 14th and the 17th day the number of the blue cells decreases and around the 22nd postnatal day they disappear completely. Simultaneously, the texture of the subependymal tissue becomes more compact. The blue cells can be identified by electron microscopy. They are characterized by the presence of several processes and contain many mitochondria, different sized vacuoles and cytosomes. The cell processes enclose subependymal cavities containing a loose flocculose material. The cells are considered as microglia cells. Their function is considered in relation to the disappearance of the loose texture of the subependymal zone.
    Materialart: Digitale Medien
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  • 156
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 141 (1973), S. 289-317 
    ISSN: 1432-0568
    Schlagwort(e): Cerebellum ; Synapses ; Rat ; Interneuron ; Axons ; Perikarya ; Neuroglia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Profiles of large neurons in the lateral nucleus range from 16 μm to 35 μm in diameter with dimpled nuclei, large Nissl bodies, and well developed Golgi apparatus. Two types of perikarya are distinguished, those that are smooth and those with irregular somatic and dendritic protuberances. About 86% of all large neuronal somata are covered with axosomatic synapses, predominantly with terminals of Purkinje axons and a few belonging to axons of the small neurons. The remaining 14% have no axosomatic synapses. The thick, fleshy dendrites of these cells are covered with terminals, the majority of which synapse directly upon the dendritic shaft. A few are present on spines. The initial segment of the large neuron is thick and robust and receives synapses upon its shaft or upon a spinous projection. The small neurons measure less than 12 μm in diameter and have very lobulated nuclei in a sparse cytoplasm characterized by small Nissl bodies and a poorly elaborated Golgi apparatus. About 52% of all small neuronal somata bear no synapses whereas the remaining 48% are covered with axosomatic synapses, mainly from the axons of Purkinje cells and a few axons of other small cells. The slender long dendrites of both large and small cells bear synapses with six classes of axons in the neuropil. Synaptic protuberances of two varieties occur on the surfaces of both perikarya and dendrites, (a) dome-shaped ones capped with a pronounced asymmetrical synaptic junction and (b) ones with thin long necks and bulbous heads having synapses on both parts. Frond-like dendritic excrescences are borne on the processes of some small and large neurons and they are postsynaptic to many axon terminals clustered around them.
    Materialart: Digitale Medien
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  • 157
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 141 (1973), S. 161-169 
    ISSN: 1432-0568
    Schlagwort(e): Rat ; Uterus ; Stroma ; Ultrastructure ; Sex steroids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effect of progesterone and oestrogen on the central uterine stroma has been examined in order to analyze what changes occur when the uterus is hormonally prepared for implantation. Both progesterone and oestrogen, when given separately, cause nucleolar enlargement and growth of the granular endoplasmic reticulum. However, after progesterone treatment the nuclei are large and spherical whereas they are spindle-shaped after oestrogen treatment. When oestrogen is administered to the progesterone-treated rat little change occurs in the stromal morphology. There is little morphological support to the view that oestrogen acts on the stroma to increase endometrial sensitivity. Further, progesterone seems to stimulate the synthesis of RNA and of cellular protein only in the stromal cell while oestrogen has a similar effect in all cell types of the uterus.
    Materialart: Digitale Medien
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  • 158
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 140 (1973), S. 153-171 
    ISSN: 1432-0568
    Schlagwort(e): Rat ; Tongue ; Myogenesis ; Neurogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Um die Entwicklung des Bewegungsapparates der Rattenzunge im Verhältnis zu morphogenetischen Vorgängen im Gesichtsbereich, besonders zur Gaumenentwicklung, beurteilen zu können, wurde die Zungenanlage des Rattenembryos ab Tag 13 p.c. bis Tag 6 p.p. lichtmikroskopisch, histochemisch und elektronenmikroskopisch untersucht. In einem Blastem von embryonalen Mesenchymzellen, Capillaren und Neuritenbündeln differenzieren sich ab Tag 15 p.c. Myoblasten, die miteinander zu mehrkernigen Muskelfasern verschmelzen. In deren Cytoplasma bilden sich an Ribosomenketten Myofilamente, die zu Myofibrillen mit Z-Streifen organisiert werden. Ab Tag 19 p.c. ordnet sich die Querstreifung zu Registern, das Transversolongitudinalsystem lagert sich an. Neuritenbündel legen sich quer zur Längsachse an die Muskelfasern an und ab Tag 17 p.c. finden sich myoneuronale Kontakte. Typische motorische Endplatten wurden bis Tag 6 p.p. nicht gefunden. Zum Zeitpunkt des Gaumenschlusses am Tag 17 p.c. sind geordnete Muskelfasersysteme, primitive myoneuronale Kontakte mit Acetylcholinvesikeln und ein typisches Enzymmuster der Acetylcholinesterase ausgebildet. Damit bestehen vor Schluß des harten Gaumens die strukturellen und enzymatischen Voraussetzungen für eine gerichtete Bewegung der Zunge. Die Hypothese, daß motorische Aktivität zum Gaumenschluß notwendig sei, wird mit Beschreibungen embryonaler Bewegungen, mit der Literatur klinisch-pathologischer Befunde der Gaumenspalte und teratologischen Experimenten verglichen. Danach scheint ein direkter kausaler Zusammenhang zwischen Bewegungen im Kopfbereich und Gaumenschluß nicht vorzuliegen.
    Notizen: Summary In order to be able to evaluate the development of the motor system of the rat tongue with respect to the morphogenetic processes in the region of the face, especially palate development, we studied the tongue anlage of the rat embryo from day 13 p.c. to day 6 p.p. histochemically and under the light and electron microscope. From day 15 p.c. onwards myoblasts differentiated out of a blastema consisting of embryonic mesenchymal cells, capillaries and neurite bundles. The myoblasts then fused together to form multinuclear muscle fibres. On the ribosome chains in the cytoplasm myofilaments were formed, which were then organized to myofibrils with Z-lines. From day 19 p.c. onwards the cross-striations came to lie next to each other and the transversolongitudinal system was added. Neurite bundles were added at right angles to the longitudinal axis of the muscle fibres, and from day 17 p.c. myoneural contacts were found. No typical motor endplates were found up to day 6 p.p. At the time of palate closure on day 17 p.c. regular muscle-fibre systems, primitive myoneural contacts with acetylcholine vesicles and a typical acetylcholine-esterase enzyme pattern had been developed. Therefore before closure of the hard palate the structural and enzymatic preconditions existed for a coordinated movement of the tongue. The hypothesis that motor activity is necessary for palate closure is compared with descriptions of embryonic movements, with clinical-pathological results in papers on the cleft palate and with teratogenic experiments. In this respect there does not seem to be any direct causal connection between movements in the head region and palate closure.
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  • 159
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 141 (1973), S. 3-37 
    ISSN: 1432-0568
    Schlagwort(e): CNS ; Cortical plate ; Neuroblasts ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In the cortical plate of the late prenatal rat fetus the neuroblasts can be considered to be of three types: mature neuroblasts which are prominent in the lower levels of the cortical plate and have some of the cytoplasmic and nuclear features of neurons, immature neuroblasts that have recently completed their migrations into the cortical plate, and migrating neuroblasts that are still in the process of moving to their definitive positions. Both of these latter types have darker cytoplasm than the mature neuroblasts. All of the neuroblasts have an apical process that extends directly towards the pial surface of the cortical plate and a basal process that is directed towards the intermediate zone of the developing hemisphere. In Golgi preparations some of these basal processes, particularly those of neuroblasts situated in the lower levels of the cortical plate, seem to have formed axons that pass through the intermediate zone to enter the developing white matter, in which they turn at right angles away from, and rarely toward, the midline. Other elements traversing the cortical plate are the ascending processes of spongioblasts that branch in the molecular layer and form expansions at the surface of the hemisphere. In the molecular layer the spongioblast terminal branches intertwine with the apical tufts of the ascending neuroblast processes and with thin processes that have the features of axons, to form a loose neuropil. In the cortical plate the spongioblast processes are usually closely and preferentially surrounded by the dark migrating neuroblasts and by the immature neuroblasts. Both of these latter may partially encompass spongioblast processes. Hence it is concluded that the spongioblast processes act as guides along which the migrating neuroblasts ascend through the cortical plate.
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  • 160
    ISSN: 1432-0568
    Schlagwort(e): Capillaries ; Endothelial cell ; Ontogenesis ; Morphometry ; Cerebral cortex ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Während der postnatalen Entwicklung wurde die Capillarlänge im Einheitsvolumen (CL), die Verzweigungsdichte (N⊥) und die mittlere Länge der Capillarendothelzellen (LE) in der Lamina IV des senso-motorischen Cortex von insgesamt 64 Rattengehirnen bestimmt. Als Capillaren wurden alle Gefäße unter 8 μm Durchmesser akzeptiert. Die CL bestimmten wir in 1–2 μm dicken Epon-Schnitten nach der Methode von Saltikov. Die Verzweigungen wurden durch Tusche-Gelatine-Injektion dargestellt und in Kryostat-Schnitten visuell gezählt. Im Verlauf des postnatalen Capillarwachstums, das die Bildung von Verzweigungen durch Sprossung und die Verlängerung der bestehenden Geäße umfaßt, nimmt die CL von ca. 200 mm auf 1100 mm pro mm3 Gewebe zu. Die Verzweigungszahl im gleichen Volumen steigt von 1200 kurz nach der Geburt auf ein Maximum von 11500 am Tag 20 und fällt dann allmählich auf den adulten Wert von 9500 ab. Am Ende der ersten Woche p.n. bewirkt die intensive Capillarsprossung eine starke Erhöhung der N⊥. Darauf folgt in der zweiten Woche p.n. die schnelle Zunahme der CL. Die Veränderungen der N⊥ laufen parallel mit Veränderungen im oxidativen Metabolismus. Aus dem Verhältnis N⊥ zu CL läßt sich der Vernetzungsgrad der Capillaren, d.h. die Verzweigungszahl pro mm Capillarlänge, berechnen. Dieser erreicht zwischen Tag 10 und 20 p.n. ein Maximum und sinkt danach bis zum erwachsenen Tier wieder beträchtlich ab. 1 Monat p.n. sind das Wachstum und die Reifung der Hirnrinde bei der Ratte weitgehend abgeschlossen. Die Bildung neuer Sprosse hört auf, und das weitere Kapillarwachstum erfolgt weniger durch Zellteilung als vielmehr durch Verlängerung des Endothels. Die Phase der intensiven Capillarsprossung entspricht zeitlich der vulnerablen Periode der Hirnentwicklung (“brain-growth-spurt”, nach Dobbing). Unsere Befunde lassen die Vermutung zu, daß in dieser Periode Störungen der Capillarsprossung indirekt das weitere Hirnwachstum beeinflussen können.
    Notizen: Summary The average length of the capillary endothelial cells (L E ), the capillary length (CL) and the number of vascular ramifications (N⊥) per unit volume in layer IV of the sensorymortor cortex from the brains of 64 Sprague Dawley rats were determined during postnatal development. All vessels less than 8 μm in diameter were accepted as capillaries. The CL was calculated according to the method of Saltikov, by counting capillary profiles in 1–2μm Epon sections. The number of ramifications per test volume were counted in 30 μm frozen sections of India-ink injected brains. Capillary growth involves both the formation of ramifications by sprouting, and the elongation of the existing vessels. During the postnatal period CL increases from 200 to 1100 mm per cubic mm tissue, the extent of branching per unit volume rises from 1200 at birth to a peak of 11500 per cubic mm at day 20 after birth, and then declines to 9500 in adults. Intensive capillary sprouting results in a marked increase in N⊥ at the end of the first week, followed by a rapid increase in CL in the second week. The changes in the ramification density run parallel with the changes in aerobic metabolism during postnatal development. The ratio N⊥/CL, i. e. the number of ramifications per mm capillary length, corresponds to the degree of arborization of the capillary net. This value rises to a maximum level between days 10 and 20 after birth and declines until maturity is attained. After 1 month the growth of rat brain is almost accomplished and the cortical structure has attained its adult characteristics. The formation of new ramifications ceases and further capillary growth occurs to a larger extent by elongation of endothelial cells and not by cell division. The phase of extensive capillary sprouting corresponds to the vulnerable period of brain development (called “brain-growth-spurt” by Dobbing). Our findings lead to the assumption that disturbances during the period of capillary proliferation can indirectly influence further brain development
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  • 161
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 142 (1973), S. 103-115 
    ISSN: 1432-0568
    Schlagwort(e): Dentinogenesis ; Dentinal globules ; Alkaline phosphatase ; Calcification ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary At the submicroscopic level, extracellular globular membrane-delimited structures have been observed in the matrix in early dentin formation in the rat. Within these “dentinal globules”, needle-like crystallites are found before apatite crystals appear in the filamentous-amorphous ground substance. In sections incubated for alkaline phosphatase, reaction products are closely associated with these globules. The possible role of the globules in initial dentin formation is discussed.
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  • 162
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 24 (1973), S. 287-303 
    ISSN: 1432-0533
    Schlagwort(e): S-100 Protein ; Experimental Neurogenic Tumors ; Nitrosourea ; Rat ; Complement Fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary S-100 protein, a soluble protein restricted to the nervous system, was measured by complement fixation in 51 neurogenic and non-neurogenic tumors produced by either methylnitrosourea or ethylnitrosourea in three different strains of rats. Nineteen of the 51 neurogenic tumors were neoplasms of the central nervous system (18 of the brain, 1 of the spinal cord). They were diagnosed morphologically as 5 mixed gliomas, 4 anaplastic gliomas, 4 glioependymomas, 1 ependymoma, 3 gliosarcomas, and 2 unclassified tumors. With the exception of one anaplastic glioma and one gliosarcoma, all other central nervous system tumors contained S-100 protein, ranging from 0.005–0.13% of the total 35000 g supernatant protein. S-100 protein was also demonstrated in 21 of the 22 tumors of the peripheral nervous system, originating from the trigeminal nerves, the spinal roots, and from peripheral nerves. The average S-100 protein content of these tumors was 0.2% (range 0.02–1.6%). A possible correlation between S-100 protein content and tumor differentiation must be evaluated. S-100 protein was detected in only one of 10 neoplasms morphologically classified as non-neurogenic (7 sarcomas, 2 carcinomas, and 1 hemangioendothelioma). On the basis of its S-100 protein content, one tumor was reclassified as a neurosarcoma. The sensitivity and the high degree of specificity of the S-100 protein assay makes it a useful biochemical tool for the identification of neurogenic tumors. The presence of S-100 protein must be considered as a definitive indication for neural cell participation in neoplastic growth.
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  • 163
    Digitale Medien
    Digitale Medien
    Springer
    Archives of toxicology 30 (1973), S. 187-198 
    ISSN: 1432-0738
    Schlagwort(e): Plasma Iron Level ; Side Effect of Drugs ; Rat ; Amphetamine ; Chlorpromazin ; Haloperidolum ; Guanethidin ; Reserpine ; α-Methyltyrosine. ; Plasmaeisenspiegel ; Arzneimittelnebenwirkungen ; Ratte ; Amphetamin ; Chlorpromazin ; Raloperidol ; Guanethidin ; Reserpin ; α-Methyltyrosin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung 4 Std nach einmaliger Gabe von 24 mg/kg d,l-Amphetamin i.p. kommt es bei Ratten zu einem Abfall des Eisens im Plasma um 40 bis 60 %. Die Reaktion ist nicht mit dem amphetaminbedingten Anstieg von Körpertemperatur und Skeletmuskelarbeit zu erklären, da sie durch Vorbehandlung mit α-Methyltyrosin, Chlorpromazin, Haloperidol, Guanethidin und Reserpin nicht unterdrückt werden kann. Jedes der zur Vorbehandlung verwandten Medikamente löst selbst bei entsprechend hoher Dosierung eine Hyposiderämie aus. 4 Std nach einmaliger Gabe von 200 mg/kg α-Methyltyrosin vermindert sich der Eisenspiegel im Plasma um 55 %, nach 10 mg/kg Chlorpromazin um 11 %, nach 5 mg/kg Haloperidol um 28 % und nach 20 mg/kg Guanethidin um 50 %. Dieser Effekt ist am ausgeprägtesten mit einer Plasmaeisenverminderung um 69 % 20 Std nach Gabe von 20 mg/kg Reserpin. Als möglicher Pathomechanismus der arzneimittelbedingten Hyposiderämie wird die Wirkung der untersuchten sämtlich zentralnervös aktiven Medikamente als “non-specific stressfull agents” sowie der durch ihre toxische Konzentration in Gang gesetzte Entgiftungsmechanismus im RES diskutiert.
    Notizen: Abstract Four hours following a single dose of 25 mg/kg of d, 1-Amphetamine in rats, a 40 to 60 % drop of plasma iron level occurred. This reaction cannot be explained by the Amphetamine-induced rise in body temperature and motor activity, since when pretreated with α-Methyltyrosine, Chlorpromazin, Haloperidolum, Guanethidin and Reserpin this was not observable. All the drugs applied for pretreatment in adequately high doses also induced hyposideremia. Four hours following a single dose of 200 mg/kg of α-Methyltyrosine, plasma iron level was reduced by 55 %, after 10 mg/kg of Chlorpromazin by 11 %, after 5 mg/kg of Haloperidolum by 28 % and after 20 mg/kg of Guanethidin by 50 %. The most pronounced effect (69 % fall) was obtained by 20 hour pretreatment with 20 mg/kg of Reserpin. As possible pathomechanism of the drug induced hyposideremia the applied drugs may be regarded as “non-specific stressfull agents”, or as another possibility, the detoxifying mechanism in RES induced by toxic concentrations of the applied drugs can be considered as responsible for this phenomena.
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  • 164
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 16 (1973), S. 466-475 
    ISSN: 1432-1106
    Schlagwort(e): Neuroglia ; Radio-autography ; Myelination ; Optic tract ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Resume Une étude, basée sur l'identification et la quantification histologique des cellules névrogliques, a été entreprise dans le tractus optique du Rat sur radio-autographies après injection de thymidine tritiée. Ce bilan a été effectué entre 2 jours et demi et 20 jours après la naissance. D'un point de vue qualitatif, trois catégories cellulaires peuvent être distinguées: les oligodendrocytes, euxmêmes subdivisés en trois classes (grands, moyens, petits), les astrocytes et d'autres varieties cellulaires parmi lesquelles la microglie. D'un point de vue quantitatif, les oligodendrocytes, en particulier les petits, sont largement majoritaires. En effet, sur toute la période examinée les oligodendrocytes représentent près de 81% de la population totale. Sur le plan radio-autographique, l'index de marquage prédomine dans la classe des moyens oligodendrocytes. Ces résultats sont discutés, notamment par rapport aux processus de myélinisation dont les phénomènes de gliose constituent le préambule direct.
    Notizen: Summary A study based on the histological identification and quantifying of the neuroglia cells, was carried out in the optic tract of the Rat on radioautographs after injection of tritiated thymidine. The assessment was made two and a half days and twenty days after birth. Qualitatively speaking, three cellular categories can be distinguished: the oligodendrocytes, themselves divided into three sorts (big, medium., small) the astrocytes and other cellular varieties including the microglia. Quantitatively speaking the oligodendrocytes, in particular the small ones, are decidedly more numerous. In fact, over the whole period under consideration the oligodendrocytes represent nearly 81% of the total population. From the point of view of the radio-autography the labeling index predominates in the medium oligodendrocyte group. These results are discussed with reference in particular to the myelination process which is preceded directly by the phenomena of gliosis.
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  • 165
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 16 (1973), S. 255-275 
    ISSN: 1432-1106
    Schlagwort(e): Rat ; Lateral vestibular nucleus ; Giant cells ; Gap junctions ; Electrotonic coupling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Correlation of morphological and electrophysiological data strongly suggest that in rat, the giant cells of the lateral vestibular nucleus (L.V.N.) are electrotonically coupled. 1. in addition to “active zones” large terminals synapsing on the perikaryon and/or the main dendritic trunk of the cells bear “gap” junctions which are interpreted as low electrical resistance pathways between neurons. 2. electrical activity of the giant cells was recorded intracellularly as the vestibulo-spinal tract was stimulated. Graded antidromic stimulation produced graded antidromic depolarizations (G.A.Ds) in 69% of cells with high threshold axons. 3. the latency of the G.A.Ds was too short to allow for chemical transmission through afferents or recurrent collaterals. 4. collision experiments demonstrated that directly evoked spikes blocked the antidromic spikes but did not block the G.A.Ds which thus were accounted for by activation of cells others than the impaled ones. 5. lesion experiments indicated that afferent fibers from the spinal cord terminate exclusively in the dorsal part of the L.V.N. Since G.A.Ds were recorded all throughout the nucleus, they were not excitatory post synaptic potentials (EPSPs) from spinal afferents. 6. when the strength of the spinal cord stimulation was increased EPSPs were also generated but they were distinct from the G.A.Ds by their latencies, time course and maximum amplitude. 7. since no direct contact is observed between neurons it is inferred that, as in other documented cases, coupling between giant cells is mediated by way of presynaptic fibers.
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  • 166
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 17 (1973), S. 133-138 
    ISSN: 1432-1106
    Schlagwort(e): Nigro-neostriatal tract ; Rat ; Survival time ; Fink-Heimer method ; Terminal degeneration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In the morphological demonstration of the nigro-neostriatal tract, there might be some discrepancies between the results by the histofluorescence method and by the degeneration silver method. The present investigation was undertaken to fill the gap by using the modified Nauta Method (Fink-Heimer) to rats surviving for varying periods after unilateral destruction of the substantia nigra. With survival time of 2–3 days, the Fink-Heimer method could demonstrate evenly and densely distributed argyrophilic spheroidal granules in the ipsilateral caudate putamen. These degenerating granules might represent the terminal degeneration of the nigro-neostriatal tract and probably correspond to the result by the histofluorescence method. From 4 days on the terminal degeneration rapidly decreased in amounts or disappeared, leaving a moderate number of beaded coarse fibers, which remained till 2 weeks. The result indicates the possibilities that the degeneration silver method could also be applicable to the demonstration of amine fibers by choosing staining condition and survival time optimal to each animal species and fiber tract.
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  • 167
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 18 (1973), S. 374-382 
    ISSN: 1432-1106
    Schlagwort(e): Growth retardation ; Hypothalamus ; Dorsomedial lesions ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Weanling rats received bilateral electrolytic lesions destroying the areas of the ventromedial (VMN) and dorsomedial (DMN) hypothalamic nuclei, respectively. Trunk blood was collected at sacrifice (Experiment 1 and 2∶ 31 days, Experiment 3∶ 14 days) for the determination of plasma growth hormone (GH) by radioimmunoassay. Rats with DMN lesions showed consistently normal to slightly elevated plasma GH levels while animals with VMN lesions showed significantly reduced plasma GH levels. Linear growth was reduced by both types of hypothalamic lesions but body weight gains and food intake were reduced only in the DMN lesioned rats. Carcass fat was greatly elevated in VMN lesioned rats, moderately elevated in one experiment in the DMN animals and normal in another experiment. These data confirm a previous hypothesis that growth retardation in DMN rats is not due to low circulating GH level but rather represents a hypocaloric-type dwarfism.
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  • 168
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 17 (1973), S. 242-260 
    ISSN: 1432-1106
    Schlagwort(e): Past and slow principal cells ; Recurrent inhibition ; Lateral geniculate body ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In urethane-anesthetized albino rats studies were made on mass potentials and/or unit activities of the lateral geniculate body (LGB) in response to single shock stimulation of optic tract (OT) and visual cortex (VC). The previous finding that LGB mass responses to stimulation of the optic nerve comprise at least two postsynaptic waves (r1 and r2) with different peak times was confirmed by OT stimulation. It was found that the r1 wave had a lower threshold and a more rapid recovery process than the r2 wave. Unit responses of principal (P) cells to maximal OT stimulation consisted of short-latency, single spikes (initial spike, IS), followed by long-latency, grouped discharges (late discharge, LD) repeated more than twice (LD1, LDr2 and so forth). Spontaneous discharges were almost completely suppressed after IS and each LD, suggesting that following these evoked discharges P cells underwent a phase of depressed excitability. The latency histogram of IS based upon 212 P cells had two peaks well-corresponding in time to the peaks of the r1 and r2 waves of the mass response, respectively. P cells were divided into the fast and slow groups according to whether their ISs occurred earlier or later than the trough separating the r1 and r2 waves. Typically, the fast cells had lower thresholds than the slow cells. The duration of the post-excitatory depression following IS and LD1 were shorter in the fast cells than in the slow cells. This same was found true with regard to the duration of depressed excitability following the antidromic firing. Examining the response patterns to OT stimulation of weak intensities, one characteristic difference between the two groups of P cells was found; the fast cells showed the IS without the succeeding LDs whereas the slow cells showed the LDs without the preceding IS. A discussion was made on functional significance of the differentiation of P cells into two types.
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  • 169
    ISSN: 1432-0533
    Schlagwort(e): Neuronal Inclusions ; Cerebrum ; Cholesterol Inhibitor ; Rat ; Electron Microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Intraperitoneal injections of a hypocholesterolemic drug, AY9944 produced neuronal cytoplasmic inclusions in the brain of Wistar strain of rats. The inclusions were numerous and larger in size in the younger age groups but gradually decreased in number and size after 30 days of age. Only a few small inclusions were seen in rats of 35 days of age or older, in spite of continuous injection of the drug. Inclusions gradually decreased in number after discontinuation of the drug in a relatively younger age group. Injection of the drug in adult rats produced only a few small neuronal inclusions. Ultrastructurally, concentrical lamellar structures were the predominant ones in younger age groups but other types of inclusions were seen in older animals and those receiving lesser amounts of the drug or those which were examined after discontinuation of the drug. This observation suggests that morphologically different inclusions can be formed by basically the same treatment if there is any difference in the metabolic activity of the target cell or the amounts of the drug. Biochemical analysis of the sterols revealed a consistently high level of 7-dehydrocholesterol up to 69 days of age, when AY9944 was administered continuously, despite the fact that there was a decrease in the number and size of the abnormal neuronal inclusions.
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  • 170
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 29 (1973), S. 253-261 
    ISSN: 1432-2072
    Schlagwort(e): Methamphetamine ; Rat ; Conditioned Aversion ; Saccharin Solution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Holtzman (Sprague-Dawley) rats which were injected in amounts ranging from 0.50–3.0 mg/kg i.p. of methamphetamine avoided a 0.1% saccharin solution which had been paired temporally with the injection, and drank water in a subsequent two-bottle choice situation under non-drug conditions. The aversion persisted for the duration of the experiment, which lasted and obtained whether the animals were fluid-deprived or fluid-satiated. Saline-injected controls, on the other hand, exhibited a 90% saccharin solution preference. Rats which received 0.25 mg/kg contiguous with the drug, or animals given 3.0 mg/kg paired with water, exhibited as extreme a preference for the saccharin solution as did the saline controls. It was concluded that neither a drugmediated taste quality change nor physiological cues associated with thirst were adequate axplanations for the avoidance behavior exhibited, but that the drug was perceived as a noxious stimulus at levels above 0.50 mg/kg under the conditions described above.
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  • 171
    ISSN: 1432-2072
    Schlagwort(e): Δ 9-THC and Δ 8-THC ; Water Intake ; Food Intake ; Body Weight ; Vocalization ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Water intake was studied in water deprived albino rats at various time intervals after injections of two tetrahydrocannabinols (Δ 9-THC and Δ 8-THC) and solvents. The dose levels used were: 1.25, 2.5, and 5.0 mg/kg of Δ 9-THC and 2.5, 5.0, and 10.0 mg/kg of Δ 8-THC. The results show a clear, dose dependent inhibitory effect on water intake as compared to the controls. Reduced intake of food was seen at 1 day post injection. This effect was, however, significant only for the groups treated with 5.0 and 10.0 mg/kg of Δ 8-THC. A decreased body weight was also recorded after the drug treatment, especially with Δ 8-THC. With respect to cannabis-induced vocalization the data suggest an increased possibility of its appearance with increasing dosages of THC.
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  • 172
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 33 (1973), S. 267-275 
    ISSN: 1432-2072
    Schlagwort(e): Yohimbine ; Intraventricular Administration ; Rat ; Locomotor Activity ; Temperature ; Narcosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The influence of yohimbine injected into the lateral cerebral ventricle on the behaviour of white Wistar rats was investigated. Yohimbine in low doses (1–5 Μg) produced excitatory effects but in high doses (20–100 Μg) it induced central depression.
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  • 173
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 31 (1973), S. 253-264 
    ISSN: 1432-2072
    Schlagwort(e): Locomotor Activity ; α-Methyl-Para-Tyrosine ; Reserpine ; l-Dopa ; Ontogenesis ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Effect of catecholamine depletion on normal hyperactivity in the neonatal rat was examined. Both α-methyl-para-tyrosine and reserpine significantly depressed behavioral arousal at 15 days postpartum, the age of greatest excitability. Heightened activity could be restored in drug-treated animals by administration of l-Dopa. These results indicate that the ontogenetic hyperactivity effect is a result of accelerated catecholamine function.
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  • 174
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 29 (1973), S. 85-89 
    ISSN: 1432-2072
    Schlagwort(e): Lithium ; Social Isolation ; Spontaneous Activity ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Group-housed rats, injected with an acute dosage of 3 meq/kg lithium chloride, were tested on an activity platform either alone or in pairs 20 min or 3 h after drug administration. Contrary to previous findings, rats administered lithium were less active than those treated with saline after both post-injection periods. However the activity of the saline control animals tested alone after 3 h was considerably less than that exhibited by the same group after 20 min. This activity difference, which could be interpreted as a lithium-social or lithium-time interaction, is more simply explained in terms of the effects of the social isolation occuring between drug administration and testing.
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  • 175
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 32 (1973), S. 313-325 
    ISSN: 1432-2072
    Schlagwort(e): 6-Hydroxydopamine ; Catecholamine Hypothesis of Depression ; Animal Model ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Two levels of permanent central norepinephrine depletion were obtained in rats by lesioning these neurons with small quantities of intraventricularly-applied 6-hydroxydopamine, and the effects of these lesions on a variety of standard tests of activity and emotional reactivity were studied. Both lesioned groups showed altered emotional reactivity; however, only the animals with less extensive lesions were hyperactive in running wheels, showed heightened shock-elicited aggression, were hyper-responsive to handling, and had a potentiated amphetamine-activation effect. It is suggested that these exaggerated behaviors reflected the sensitization and regeneration of partially lesioned noradrenergic circuits. These data are discussed in terms of the catecholamine hypothesis of depression.
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  • 176
    ISSN: 1432-2072
    Schlagwort(e): Amphetamine ; Apomorphine ; Neuroleptics ; Dopamine ; Drinking Behaviour ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Hypodipsia produced by injection of d-amphetamine (2.0 mg/kg) or apomorphine (0.8 mg/kg) in rats, was partially antagonized by two DA-specific neuroleptic drugs, Pimozide and Spiramide, respectively. Pimozide revealed a maximal amphetamine-antagonistic effect at dose levels between 0.1–0.4 mg/kg. Hypodipsia could also be produced by Pimozide alone in doses greater than 1.0 mg/kg. Pretreatment of the apomorphine-induced hypodipsia with 0.05 mg/kg Spiramide also reliably counteracted drinking deficits. The interaction of water deprivation combined with the presence or absence of food in the test situation was also examined, but no effect was found. The possibility that perseverative rearing on the hind legs under d-amphetamine might interfere with drinking was tested with high vs. low drinking-tubes in the Pimozide-amphetamine experiments. There was evidence for a slight initial effect of drinking position, but the general form of the dose-response curve was not greatly altered. It was concluded that dopamine effects cannot easily be excluded from a role in the control of drinking, and that the primary role often accorded norepinephrine in relation to amphetamine effects should be re-examined with respect to the specific behavioural functions which are altered.
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  • 177
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 31 (1973), S. 77-90 
    ISSN: 1432-2072
    Schlagwort(e): Rearing ; Locomotion ; Exploratory Behaviour ; Psychotropic Drugs ; Anxiolytics ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The “staircase” is a simple and rapid test and was used to study two components of exploratory behaviour in the rat. The scores of rearing and the number of steps climbed during three minutes were recorded. Various psychotropic drugs were tested, which modified these two parameters. Neuroleptic induced a parallel decrease of both, while benzodiazepines, meprobamate, amobarbitone and ethanol decreased the rearing at doses which left the steps climbed unchanged. At high doses, there was a parallel decrease of both parameters. Amphetamine, at lower doses, increased the rearing score alone. The comparison of the studied psychotropic drug effects with those of two muscle relaxants (by a comparison of the slopes of regression lines) suggests that either the observed benzodiazepine effects were only partly due to their myorelaxant action, or, that both myorelaxants have some anxiolytic action. The effect of amphetamine at low doses can be viewed as a demonstration of increased anxiety.
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  • 178
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 31 (1973), S. 157-166 
    ISSN: 1432-2072
    Schlagwort(e): Δ 9-tetrahydrocannabinol ; Predatory Aggression ; Rat ; Serotonin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Δ 9-tetrahydrocannabinol inhibits predatory aggression in rats. Increases in the degree of inhibition are obtained with increasing dosages of the drug. Although sex and strain of the subjects varied nonsystematically, inhibition of predatory aggression uniformly was found to be dose related. Readministration of Δ 9-tetrahydrocannabinol did not effect motor activity measures at dose levels which inhibit aggression. Administration of Δ 9-tetrahydrocannabinol increases whole brain serotonin, while norepinepherine is largely unaffected, indicating that the anti-aggressive effect may be mediated, in part, by serotonergic mechanisms.
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  • 179
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 28 (1973), S. 243-246 
    ISSN: 1432-2072
    Schlagwort(e): δ 1-THC ; Copulation ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The mating behavior of 15 male rats was measured after treatment with δ 1(2)-tetrahydrocannabinol (THC) and propylene glycol (vehicle). Administration of either 2 mg per kg or 3 mg per kg body weight of THC was followed by significant increases in latency to the first mount, latency to ejaculation, and latency to the first mount following ejaculation. No significant changes were found in the number of intromissions or mounts. The deterioration in sexual performance is interpreted as reflecting a decreased motivation to copulate under the influence of the drug.
    Materialart: Digitale Medien
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  • 180
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 32 (1973), S. 351-358 
    ISSN: 1432-2072
    Schlagwort(e): Fenfluramine ; FR Responding ; Behavioural Tolerance ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Two experiments on the effects of fenfluramine on FR responding are reported. In Experiment 1 two rats were trained on an FR 10 schedule of reinforcement. After more than 30 h training, intraperitoneal injection of saline, 2, 4 and 8 mg/kg fenfluramine were given. Disruption of the initial stages of responding was noted after 2 and 4 mg/kg, with complete disruption of responding in 1 animal after 8 mg/kg administration. In Experiment 2, 2 rats trained on an FR 30 schedule of reinforcement received chronic 15 days administration of 4 mg/kg fenfluramine. Disruption of responding was noted after the first administration. The degree of disruption lessened by the fifteenth day of administration.
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  • 181
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 28 (1973), S. 87-94 
    ISSN: 1432-2072
    Schlagwort(e): Psychopharmacology ; Intragastric ; Self-Administration ; Benzodiazepines ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A technique for intragastric self-administration in rats is presented. Intravenous self-administration of morphine was compared with intragstric self-administration during 6 consecutive days. There was no difference between the two routes in the total rate of injections. Medazepam was given for intragastric self-administration at three different doses (2.5, 5.0 and 10.0 mg/kg/injection respectively) and compared with saline. There was an increased response rate at the dose 10 mg/kg/injection. Medazepam placebo solution (solvent alone) was also compared with medazepam 10 mg/kg/injection. Among the seven experimental rats, six responded higher on medazepam than on the solvent.
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  • 182
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 30 (1973), S. 375-384 
    ISSN: 1432-2072
    Schlagwort(e): Schedule-Controlled Behavior ; Adjunctive Behavior ; Licking ; Drinking ; Methamphetamine ; Chlordiazepoxide ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effects of methamphetamine (0.03–1.7 mg/kg) and chlordiazepoxide (3.0–30.0 mg/kg) were studied in a situation in which the same motor response, licking a water-filled tube, served as a schedule-controlled and as an adjunctive behavior. Rats responded under a 3-min fixed-interval (FI) schedule of food presentation in which the required response was a lick on the tube (schedule-controlled); licking also occurred following every food presentation (adjunctive). Adjunctive licking occurred at a high, steady rate, but schedule-controlled licking was emitted at a changing rate over time, characteristic of FI schedules. Both drugs had little effect on overall adjunctive licking, except for decreases at the highest doses, but there were changes in the pattern of adjunctive licking. Methamphetamine produced only decreases in schedule-controlled licking, but chlordiazepoxide produced dose-dependent increases. In general, the magnitude of drug effect on local rates of responding within the FI was related to control rates of responding within the same periods, but there were instances in which the magnitude of effect depended also on whether licking was adjunctive or schedule-controlled.
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  • 183
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 345 (1973), S. 73-79 
    ISSN: 1432-2013
    Schlagwort(e): Gastrosecretagogue ; Gastrin ; Rat ; Bile
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effect of GSP, a gastrosecretagogue fraction extracted from hog pancreas, on bile secretion has been studied in rats provided with a bile duct canula and compared with the effect of antral gastrin. GSP showed no effect on bile secretion, concentration and output of bilirubin and electrolytes in the bile. On the other hand gastrin is significantly increasing bile output, bilirubin concentration and output in the bile. No effect of gastrin on the excretion rate of sodium and potassium in the bile has been observed.
    Materialart: Digitale Medien
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  • 184
    ISSN: 1432-2013
    Schlagwort(e): Pulmonary Diffusing Capacity for CO ; Cardiac Output ; Oxygen Dissociation Curve ; High Altitude ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In rats born in the low pressure chamber from sea level parents a higher hypoxic steady-state pulmonary diffusing capacity for CO was found as compared with controls of similar body weight. This difference could be explained by a difference in age or by an increase of blood O2 capacity. There was no difference in alveolar ventilation and alveolar-arterial O2 pressure differences, a lower cardiac output, no difference in arterial O2 tension, no difference in arterial O2 content but a decreased mixed-venous O2 content as compared with control rats measured at hypoxia. A shift of the standard blood O2 dissociation curve to the right was found in the simulated high altitude exposed rats. Calculated mixed-venous O2 pressure was not altered in these rats; since arterial O2 pressure was the same no difference in mean tissue capillary O2 pressure may be presumed as compared with control animals. The results suggest that the first generation of rats exposed to simulated high altitude for their whole life is not only less adapted than animals exposed in their youth (as described in previous work) but that the ability to promote the O2 transport in time of need in rats born in the low pressure chamber is probably even inferior to that of the controls.
    Materialart: Digitale Medien
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  • 185
    ISSN: 1432-2013
    Schlagwort(e): Myoglobin ; Heart ; High Altitude ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Reynafarje's (1963) spectrophotometric method was modified for the study of myoglobin concentration in rat hearts. The influence of age and body weight was evaluated and the age was found to be better correlated with myoglobin concentration than the weight. The influence of simulated altitude of 3500 m was studied in animals exposed to hypoxia at the age of about 34 days and in animals born in the low pressure chamber. In the first group a higher myoglobin concentration was found but only in the right ventricle, together with unilateral hypertrophy, as compared with control animals. In the group of animals born at simulated altitude a severe cardiomegaly developed which was most pronounced in the right ventricle. The myoglobin concentration in the hearts from this group was unchanged in the right ventricle and was lower in the left ventricle and septum.
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  • 186
    Digitale Medien
    Digitale Medien
    Springer
    Research in experimental medicine 161 (1973), S. 133-140 
    ISSN: 1433-8580
    Schlagwort(e): Self-emptying loop ; Mucosal atrophy ; Small intestine ; Luminal nutrition ; Morphology ; Glucose-absorption ; Rat ; Selbstentleerende Blindschlingen des Jejunums ; Schleimhautatrophie ; Topische Ernährung ; Morphologie ; Glucoseresorption ; Ratte
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Um Möglichkeit und Ausmaß der Reversibilität einer Dünndarmschleimhautatrophie zu prüfen, wurden operativ ausgeschaltete, atrophische Jejunalschlingen nach Rückverlegung in die Dünndarmpassage morphologisch und funktionell untersucht. Ergebnisse: 1 Monat nach Rückverlegung hatte sich die Schleimhautatrophie zurückgebildet. Morphometrisch fand sich darüber hinaus eine Hypertrophie aller Wandschichten. Der Schleimhauthypertrophie entsprach eine Steigerung der Glucoseresorption.
    Notizen: Summary Self-emptying blind loops of the small intestine in the rat were restored to functioning intestine in order to investigate the reversibility of mucosal atrophy. Results: 1 month after restoration of normal anatomical conditions atrophy was no longer demonstrable. In addition, the morphometric data indicated mucosal hypertrophy and increase in thickness of all layers of the intestinal wall. These changes were associated with a significant increase of glucose-absorption.
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  • 187
    Digitale Medien
    Digitale Medien
    Springer
    Research in experimental medicine 161 (1973), S. 289-297 
    ISSN: 1433-8580
    Schlagwort(e): D-penicillamine ; L-cysteine ; Serum proteins ; Rat ; D-Penicillamin ; L-Cystein ; Serumproteine ; Ratte
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung In vitro-Untersuchungen zeigten, daß D-Penicillamin durch Serumproteine, in erster Linie durch Albumin, gebunden wird. Aller Wahrscheinlichkeit nach ist die Bildung gemischter Disulfide hierfür verantwortlich. Cystin, L-Cystein und andere Thiole sowie N-Äthylmaleinimid hemmen die Proteinbindung von D-Penicillamin. Verabfolgt man Ratten vor Injektion des D-Penicillamins L-Cystein, resultiert eine vorübergehende Erhöhung des Gehalts an freiem D-Penicillamin in Serum und in einigen Geweben, während die Ausscheidung mit dem Urin verzögert wird. Die theoretische und praktische Bedeutung der Befunde wird diskutiert.
    Notizen: Summary Studiesin vitro show that D-penicillamine is bound by serum proteins, mainly albumin; the formation of a mixed disulfide is the most likely explanation. Cystine, L-cysteine and other thiols as well as N-ethylmaleinimide were found to inhibit the protein binding of D-penicillamine. Administration of L-cysteine to rats prior to D-penicillamine brings about a transient increase of the amount of free D-penicillamine in serum and in some tissues as well as a delay in its urinary excretion. The theoretical and practical implications of the findings are discussed.
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  • 188
    Digitale Medien
    Digitale Medien
    Springer
    Langenbeck's archives of surgery 333 (1973), S. 211-236 
    ISSN: 1435-2451
    Schlagwort(e): Anastomosis ; Experimental Carcinoma ; Gastric Stump ; Nitrosoguanidine ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Das für die Magenkrebsforsehung bedeutsame Ergebnis unserer an insgesamt 100 Wistarratten durchgeführten Untersuchungen ist die Feststellung, daß im resezierten Magen der Versuchstiere nach oraler Gabe des unterschwellig dosierten Carcinogens Nitrosoguanidin in hoher Ausbeute (65,1%) Carcinome (Adenocarcinome) und Präcancerosen entstehen. Die malignen Veränderungen weisen im Hinblick auf Lokalisation und Wachstumsrichtung formale Ähnlichkeiten mit dem Magenstumpfcarcinom des Menschen auf: sie sind nahezu ausschließlich auf den Bereich der gastroenteralen Anastomose beschränkt und verschonen beim infiltrierend-destruierenden Wachstum den Dünndarm. Dieses experimentelle Carcinom im operierten Magen wird als Anastomosencarcinom bezeichnet; es erscheint als Versuchsmodell zum Studium des Magenstumpfcarcinom geeignet. Der Vergleich der cancerösen und präcancerösen Veränderungen der magenresezierten Tiere mit den nicht operierten Kontrolltieren zeigt einen hochsignifikanten Unterschied: Bei nicht operierten, jedoch mit einem Carcinogen behandelten Kontrolltieren trat ebenso wie bei operierten, nicht mit einem Carcinogen exponierten Tieren in keinem Fall ein Anastomosencarcinom und nur in einem Fall eine Präcancerose auf. Die Befunde beweisen, daß weder die Exposition durch das unterschwellig dosierte Carcinogen noch die Disposition durch Anlage einer gastroenteralen Anastomose als Einzelfaktoren für sich betrachtet ausreichend sind, um innerhalb der gewählten Versuchszeit ein Anastomosencarcinom zu erzeugen. Treffen beide Faktoren jedoch zusammen, so wird das Krebswachstum im Sinne einer Syncarcinogenese induziert. Die Art der gewählten gastroenteralen Anastomose (Billroth I oder Billroth II) ist ohne Bedeutung für die Häufigkeit des Anastomosencarcinoms. Im Hinblick auf die Pathogenese des Magenstumpfcarcinoms ergeben sich aus unseren Befunden, unter Respektierung der Prämissen des Analogieschlußverfahrens, folgende Feststellungen: 1. Der resezierte Magen ist im Bereich der Anastomose zur Carcinomentstehung disponiert. 2. Wenn zur Disposition die Exposition durch äußere Carcinogene tritt, so wird an dieser Stelle das Krebswachstum induziert.
    Notizen: Summary 66 male Wistar rats, subjected to gastric resection according to Billroth I or Billroth II and subsequently exposed to Nitrosoguanidine as oral carcinogen, developed carcinomas and precancerous lesions at a rate of 65,1%. The tumours were characterized histologically as adenocarcinomas; they were almost exclusively localized in the region of the gastroduodenal or gastrojejunal anastomosis. The process of cancer development was completed within 17 to 31 weeks on continous administration of 120 mg/l of Nitrosoguanidine in the drinking water. 34 control animals either with intact stomachs subjected to the carcinogen or operated and kept under normal drinking water showed no cancer formation. Only one precancerous lesion (adenomatous hyperplasia) could be observed in the control group with intact stomachs. Trying to relate the present findings to the occurrence of gastric stump carcinoma in man the following conclusions can be made: 1. The operated stomach is predilected for cancer development. 2. Exposure of the operated stomach to an oral carcinogen induces carcinogenesis prevalent in the anastomosic region.
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  • 189
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 136 (1973), S. 111-120 
    ISSN: 1432-0878
    Schlagwort(e): Median eminence ; Rat ; Granular vesicles ; Ultrastructure ; Quantitative evaluation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In order to characterize different sub-zones in the palisade zone of the rat median eminence, quantitative ultrastructural parameters were applied to brains fixed in aldehyde-osmium tetroxide. The palisade zone has been subdivided in 4 successive sub-zones. Increasing numbers of granular vesicles (GV), especially those smaller than 110 nm, are observed from dorsal to ventral sub-zones. There also are more GV per unit area of nervous tissue in the perivascular than in the more dorsal sub-zones. The individual nerve profiles exhibit a larger size in the perivascular layer than in the more dorsal areas, whereas the number and size of nerve profiles devoid of vesicles diminish from dorsal to ventral. As a consequence more GV occur in the perivascular nerve profiles. In the GV containing nerve profiles the concentration of GV is, however, constant in the different sub-zones. A fluctuating size of the preterminal and terminal parts of the nerve fibres is suggested.
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  • 190
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 139 (1973), S. 101-148 
    ISSN: 1432-0878
    Schlagwort(e): Infundibulum ; Rat ; Neuro-glial synapses ; Neuro-Vascular contacts ; Corticotropin-Releasing Factor ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung 1. Die Gefäßfortsätze von ependymalen und subependymalen Zellen bilden in der subependymalen Zone und in der Zona interna des Ratteninfundibulum mit Nervenfasern kompakte neuro-gliöse Faserbündel, die sich in der Zona externa aufzweigen. 2. In allen Zonen des Infundibulum kommen zwischen den Nervenfasern und den Gefäßfortsätzen zahlreiche neuro-gliöse Synapsen vor. In den Gefäßfortsätzen fällt die hohe Zahl an Mikrotubuli sowie die zahlreichen, vielgestaltigen Einschlüsse auf. 3. In der subependymalen Zone sind die Interzellularspalten an bestimmten Stellen außerordentlich weit. Sie haben eine kanalartige Beschaffenheit und enthalten feine Bündel von Nervenfasern. 4. Von den lateralen Anteilen des Infundibulum her erreichen Dendriten von Ganglienzellen des Nucleus infundibularis die Mitte des Infundibulum. In dieser Region sind axodendritische Synapsen anzutreffen. 5. Morphometrische Analysen der Nervenfaserendigungen der Zona externa von Normaltieren zeigen, daß die prozentuale Verteilung der nach Granulagröße differenzierten Nervenfaserklassen für Mitte und Seite der Zona externa etwa gleich ist. Zwischen der Größe der Elementargranula und der Anschnittfläche der zugehörigen Nervenfasern besteht eine direkte Beziehung. 6. Die Nervenfaserendigungen erreichen die Basalmembran des perikapillären Raumes fast ausschließlich im Bereich von gefäßwärts gerichteten Vorwölbungen der Zona externa. Das Ausmaß, in dem Nervenfasern im Vergleich zu den Gefäßfortsätzen von Ependymund Gliazellen den perivaskulären Raum erreichen, ist medial weitaus größer als lateral. 7. Bei bilateral adrenalektomierten Ratten nimmt in bestimmten, vorwiegend lateral gelegenen Nervenfasern die Zahl und Größe der Elementargranula in Abhängigkeit von der Überlebensdauer zu. Dies dürfte auf eine verstärkte Synthese und Speicherung von Corticotropin-Releasing Factor in diesen Nervenfasern zurückzuführen sein. Gegenüber dem Normalbefund ist die neurohämale Kontaktfläche erheblich vergrößert. Der perivaskuläre Raum enthält zerfallene Nervenfaserteile, die durch Bindegewebszellen phagocytiert werden. Diese Veränderungen dürften durch eine unter Versuchsbedingungen verstärkte Wachstumstendenz der Nervenfasern in Richtung auf die Blutgefäße und durch eine Abschnürung der Nerven-faserendigungen ausgelöst werden.
    Notizen: Summary 1. In the subependymal and internal zones of the rat median eminence nerve fibres and vascular processes of ependymal and subependymal cells form neuro-glial bundles. They branch in the external zone. 2. In all these three zones of the infundibulum numerous neuro-glial synapses are found between nerve fibres and vascular processes of glial cells. The vascular processes contain a high number of microtubules as well as polymorphous granular inclusions. 3. In certain regions of the subependymal layer the intercellular spaces are enlarged. They form channel-like spaces containing small bundles of delicate nerve fibres. 4. Nerve cells of the infundibular nucleus located in the lateral parts of the infundibulum send dendrites to the medial parts of the infundibulum. In this area axo-dendritic synapses are found. 5. For morphometric analysis, the nerve fibres of the external zone were classified according to the diameter of their granules. It is shown that in the different regions of the external zone the distribution of the various types of nerve fibre is similar. Moreover it can be seen that a direct correlation exists between the size of the sectional plane of a given nerve fibre and the size of the granules it comprises. 6. Nerve fibre endings abutting on the basement membrane of the pericapillary space are mostly found in bulb-like protrusions of the external zone. The extent to which nerve fibres reach the perivascular space—as compared with the vascular processes of ependymal and glial cells—is higher in the medial than in the lateral parts of the infundibulum. 7. In bilaterally adrenalectomized rats the number and diameter of elementary granules increases in nerve fibres located laterally. This increase is directly related to the survival time and may be due to an enhanced synthesis and storage of Corticotropin-Releasing Factor in these nerve fibres. Compared with the findings in untreated animals the neurohemal contact area is significantly enlarged. The perivascular space contains degenerating nerve fibres which are undergoing phagocytosis by connective tissue cells. It is assumed that these alterations are due to the increased growth of nerve fibres towards the vessels of the “Mantelplexus”, and that, following adrenalectomy, this excessive growth leads to a pinching off of nerve fibres.
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  • 191
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 136 (1973), S. 177-182 
    ISSN: 1432-0878
    Schlagwort(e): Rat ; Epididymis ; Effect of vasectomy ; Spermatozoa ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Epididymal biopsies from rats that had undergone unilateral or bilateral vasectomies from one to eight months previously were compared with biopsies from their contralateral side or from normal controls to ascertain what ultrastructural changes had occurred. After vasectomy, spermatozoa appeared to dissolve in the lumen of the caput epididymidis and to be absorbed by the principal cells. About 5 weeks after vasectomy, numerous lamellar accumulations became apparent in the supernuclear region. Their resemblance to lysosomes or residual bodies was confirmed by an acid phosphatase reaction. After 10 weeks, similar lamellar and polymorphic accumulations on the contralateral side of animals with unilateral vasectomies indicated that resorption had also increased on the unligated side.
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  • 192
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 137 (1973), S. 271-280 
    ISSN: 1432-0878
    Schlagwort(e): Dental enamel ; Rat ; Ultrastructure ; Crystallography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Thin sections of rat incisor enamel were studied with the electron microscope. Fringe patterns having repeat periods in the range 3.1–8.2 Å were seen in individual enamel crystals. These images were interpreted as representing the resolution of corresponding planes in the hydroxyapatite crystal lattice. The lattice spacings and interplanar angles were identified by comparing the observations with available data derived from X-ray diffraction analysis.
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  • 193
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 140 (1973), S. 309-314 
    ISSN: 1432-0878
    Schlagwort(e): Pituitary Gland ; Rat ; Somatotropin ; Cellular Response ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The response of somatotrophs to large doses of purified bovine growth hormone was examined in uninephrectomized rats drinking 1% sodium chloride in an attempt to prolong the action of the hormone. Growth hormone produced a triphasic response in the ultrastructure of somatotrophs. Uninephrectomy and salt alone induced no changes in somatotrophs as compared to unoperated animals consuming tap water. In the first phase (3 days) the cross sectional area of the cell increased, the size of the largest granule per cell as well as the number of granules per cell increased significantly. All these parameters then reached control level after 7 days of injections during a second phase. Suppression of somatotrophs by exogenous growth hormone was evident by 16 days (third phase) when the area of the cell, the size of the largest secretory granule as well as the number of granules per cell all decreased significantly. Somatotrophs apparently did not react to suppression by a lysosomal mechanism inasmuch as no increase in the number of lysosome-derived structures was seen even at 16 days.
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  • 194
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 143 (1973), S. 505-515 
    ISSN: 1432-0878
    Schlagwort(e): Endoplasmic reticulum ; Paracervical ganglion (Rat) ; Neurosecretion ; Electron microscopy ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Two new types of structure of the cytoplasm of an autonomic neuron were described: (1) Inclusions of the rough ergastoplasmic reticulum, which were named “ergastosomes”, contain finely granular material with moderately electron opaque staining with both glutaraldehyde-OsO4 and KMnO4 fixations. A short comment was made on the nature of the contents of the ergastosomes. (2) Tubular formations of endoplasmic reticulum were found in the axons and/or dendrites of the paracervical ganglion.
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  • 195
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 146 (1973), S. 207-221 
    ISSN: 1432-0878
    Schlagwort(e): Substantia nigra ; Rat ; Six bouton types ; Strio-nigral projection ; Bouton degeneration ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The normal ultrastructure of rat substantia nigra was investigated. Special attention was paid to the different types of boutons, and the mode of termination of the striatonigral connection was examined. Two different types of nigra neurons with deep nuclear membrane indentations were observed. The synaptic organization of rat substantia nigra is very complex. Six types of boutons, with many characteristics, could be differentiated: pleomorphicvesicle boutons (40%), elongated-vesicle boutons (10%), small-round-vesicle boutons (10%), large-round-vesicle boutons (20%), “clear-terminal” (15%) and dense-core-vesicle boutons (about 5%). Vesicle-containing dendrites were observed entering dendro-dendritic synapses. One to four days after large unilateral striatal lesions were made, a great number of degenerating boutons were seen in the ipsilateral substantia nigra, while the contra-lateral substantia nigra was entirely free of degeneration. The newly defined pleomorphic-vesicle boutons were found almost exclusively in the process of degeneration. The neuronal origin of the other bouton types is discussed.
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  • 196
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 138 (1973), S. 223-237 
    ISSN: 1432-0878
    Schlagwort(e): Aorta, endothelium ; Rat ; Transport of serum lipoproteins ; Radioautography ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The transport of 125I-labeled serum lipoproteins through the aortic endothelium was studied by radioautography. Rat aorta and heart was perfused in vitro with a medium containing human very low density (VLDL), low density (LDL), high density lipoprotein (HDL), delipidated HDL apolipoprotein or rat HDL. In all lipoproteins more than 95% of the radioactivity was TCA precipitable and lipid radioactivity was from 2–4% in HDL, 4–6% in LDL, 7–15% in VLDL. After 18–60 min of perfusion and wash with unlabeled medium, most of the aortic radioactivity was TCA precipitable and the percent of lipid counts was similar to that in the original lipoprotein. Following perfusion with VLDL, LDL, or HDL the radioautographic reaction was seen over the endothelium, the subendothelial space and the inner media, and was separated by an unlabeled zone from the reaction present over the adventitia. Uniform labeling of the entire wall was found after perfusion with HDL apolipoprotein. The presence of silver grains over endothelial cells in regions rich in plasmalemmal vesicles suggested that these organelles participate in the transport of the labeled lipoprotein, as was shown for lactoperoxidase (Stein and Stein, 1972). The present data indicate that cholesterol may enter the aortic wall as a constituent of lipoprotein particles. Since an HDL particle carries less than 1/20 of the cholesterol present in a LDL particle, it seems that the lower susceptibility of the female to atheromatosis might be related to the higher ratio of HDL to LDL particles in the female serum.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 197
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 138 (1973), S. 261-272 
    ISSN: 1432-0878
    Schlagwort(e): Extrarenal blood vessels ; Rat ; Adrenergic nerves ; Fluorescence microscopy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The adrenergic innervation of the extrarenal blood vessels of the rat left kidney was investigated by fluorescence histochemistry and by electron microscopy. The trunk of the renal artery proximal to the aorta is elastic and appears to be very sparsely innervated. In contrast, near the kidney the renal artery—which divides into 3 to 4 large branches of the muscular type possesses a dense adrenergic innervation. The adrenergic terminal axons are situated in the adventitia close to the external elastic lamella, but only rarely in close contact with smooth muscle cells. In most instances several terminal axons are grouped and enclosed by a Schwann cell, single axons being rare. All terminal axons are able to take up and to store 5-hydroxydopamine which strongly suggests that they are adrenergic. The innervation of the renal vein is more sparse than that of the muscular arteries but somewhat denser than that of the elastic artery. In addition, close to the origin of the renal artery the presence of “small intensively fluorescent” (SIF) cells as well as of some adrenergic ganglion cells is noted. The latter are situated in the adrenergic nonterminal axon bundles, which run parallel to the blood vessels. It is concluded that the uneven adrenergic innervation along the artery as well as individual variations in the branching of the artery are the main causes of the unusually high individual variations of the NA content of this organ such as used in pharmacological experiments.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 198
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 136 (1973), S. 511-520 
    ISSN: 1432-0878
    Schlagwort(e): Muscle spindle ; Sensory ending ; Rat ; Development ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A fine structural study of sternothyroid muscle spindles of young adult rat demonstrates the rare occurrence of unique nerve endings. These endings are situated in the juxta-equatorial region of nuclear-bag fibers, adjacent to the annulo-spiral sensory endings. They consist of a bundle of terminal axons less than 0.3 μ in diameter and appear to be disposed nearly longitudinally to the axis of the intrafusal fibers. Whereas, the annulo-spiral endings consist of a single axon, coiling around the intrafusal fibers. Transverse sections of these muscle spindles reveal these unique endings scattered around the muscle fibers, fitting into depressions on their surface. The innermost axons directly face the muscle surface and are separated by a narrow gap less than 200 Å in width. No Schwann cell process appears to be associated with these endings. From their unique multi-axonal composition, these endings are termed “bundled endings”. Investigations of developing muscle spindles show the occasional presence of a similar multi-axonal composition of sensory endings in perinatal rats. It is suggested that “bundled endings” are sensory in nature, carrying an immature feature over to adult life.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 199
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 137 (1973), S. 141-143 
    ISSN: 1432-0878
    Schlagwort(e): Juxtaglomerular cells ; Rat ; Granulation index ; Diurnal rhythm ; Statistical evaluation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Das Granulations-Index der juxtaglomerulären epitheloiden Zellen der Rattenniere unterliegt tagesrhythmischen Schwankungen, wobei die berechneten Werte in den Nachtstunden significant höher sind als in den Tagesstunden.
    Notizen: Summary Marked diurnal changes occur in the granulation index of the juxtaglomerular cells in the rat kidney. According to the results the night values are significantly higher than those obtained in daytime.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 200
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 138 (1973), S. 63-73 
    ISSN: 1432-0878
    Schlagwort(e): Adenohypophysis ; Rat ; Gonadotrophic cells ; Cycle, influence of testosterone ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 4-day cyclic adult female Wistar rats were injected subcutaneously with testosterone propionate on diestrus 1 at 16:00 and on diestrus 2 at 10:00 respectively. Non-injected females served as controls. Autopsy was performed on diestrus 2 at 23:00, and on proestrus at 14:00 and 17:00 respectively. The blue Alcian-PAS staining was used to evidence FSH (β) and LH (γ) pituitary cells. In control animals and in diestrus 2 injected females only a small number of FSH cells could be detected on diestrus 2 at 23:00. This number increased markedly on proestrus at 14:00 and decreased on proestrus at 17:00. A similar evolution was observed in diestrus 1 testosterone injected females, but the number of FSH cells appeared higher at any stage of autopsy in these females than in diestrus 2 injected females and in control rats. In control females, numerous LH cells were observed on diestrus 2 at 23:00. The number of these cells was diminished on proestrus at 14:00 and still more at 17:00. On the contrary few LH cells were detected in testosterone injected females on the evening of diestrus 2. An increase of these cells occurred on proestrus at 14:00, followed at 17:00 by only a weak diminution as established by comparison with control animals. An inhibition of FSH release and a suppression of the proestrus surge of LH were therefore supposed to cause, on one hand, the slowing up of follicular growth observed in diestrus 1 injected females and, on the other hand, the blockage of ovulation noted in both diestrus 1 and diestrus 2 treated animals.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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