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  • 75.10.Jm  (2)
  • Cardioplegia  (2)
  • Immobilization  (2)
  • Mitochondrial swelling  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Nitrogen transformation in arable soils of North-West Germany during the cereal growing season (1996)
    Springer
    Biology and fertility of soils 22 (1996), S. 179-183 
    Details
    ISSN: 1432-0789
    Keywords: Microbial N ; Immobilization ; Remobilization ; NH inf4 sup+ fixation ; Exchangeable NH inf4 sup+
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In 1991, field experiments on loess (with winter wheat) and sandy soils (with summer barley) were conducted to study N dynamics in the microbial biomass and non-exchangeable NH inf4 sup+ . The measurements showed a mass change in microbial N, with a maximum increase of 100 kg N ha-1 30 cm-1 from March to July in the loess soil, and a change for only 1 month (May) in the sandy soil. Plots treated with conventional levels of N fertilizer (213 kg N ha-1 on a loess soil to winter wheat and 130 kg ha-1 on the sandy soil to summer barley), reduced levels of N (83% and 62% of the conventional N application), or no N showed no consistent fertilizer N effect on microbial biomass N. From March to July, non-exchangeable NH inf4 sup+ in loess soils under winter wheat decreased by 110 kg N ha-1 30 cm-1 in conventionally fertilized plots and by 200 kg N ha-1 30 cm-1 in a plot with no N fertilizer. After harvest, the pool of non-exchangeable NH inf4 sup+ increased due to increasing mineral N concentrations in the soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384452
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  • 2
    Electronic Resource
    Electronic Resource
    Nitrogen transformation in arable soils of North-West Germany during the cereal growing season (1996)
    Springer
    Biology and fertility of soils 22 (1996), S. 179-183 
    Details
    ISSN: 1432-0789
    Keywords: Key words Microbial N ; Immobilization ; Remobilization ; NH4+ fixation ; Exchangeable NH4+
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In 1991, field experiments on loess (with winter wheat) and sandy soils (with summer barley) were conducted to study N dynamics in the microbial biomass and non-exchangeable NH4 +. The measurements showed a mass change in microbial N, with a maximum increase of 100 kg N ha–1 30 cm–1 from March to July in the loess soil, and a change for only 1 month (May) in the sandy soil. Plots treated with conventional levels of N fertilizer (213 kg N ha–1 on a loess soil to winter wheat and 130 kg ha–1 on the sandy soil to summer barley), reduced levels of N (83% and 62% of the conventional N application), or no N showed no consistent fertilizer N effect on microbial biomass N. From March to July, non-exchangeable NH4 + in loess soils under winter wheat decreased by 110 kg N ha–1 30 cm–1 in conventionally fertilized plots and by 200 kg N ha–1 30 cm–1 in a plot with no N fertilizer. After harvest, the pool of non-exchangeable NH4 + increased due to increasing mineral N concentrations in the soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384452
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The ultrastructural effects of global ischaemia on Purkinje fibres compared with working myocardium: A qualitative and morphometric investigation on the canine heart (1991)
    Springer
    Virchows Archiv 418 (1991), S. 17-25 
    Details
    ISSN: 1432-2307
    Keywords: Purkinje fibres ; Ischaemia tolerance ; Qualitative and quantitative ultrastructure ; Cardioplegia ; Arrhythmias
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary During open heart surgery, reperfusion-induced arrhythmias arising after short periods of ischaemia may originate from subendocardial Purkinje fibres. We investigated the ultrastructure of these fibres during 30 min of global ischaemia at 25° C. The effects both with myocardial protection (HTK cardioplegia) and without it (pure ischaemia) were compared qualitatively and morphometrically. After 30 min pure ischaemia overcontraction of sarcomeres, hypercontraction and contraction bands, together with considerable changes in organelles, predominate over cellular oedema. In Purkinje fibres, both cellular and mitochondrial swelling were significantly increased within this 30-min time period from the onset of pure ischaemia. In contrast, following HTK cardioplegia and 30 min ischaemia, cellular and mitochondrial swelling remain moderate and over-contractions are almost entirely lacking. This means that despite remarkable differences between pure ischaemia and HTK cardioplegia in the degree of protection attained it is clear that, compared with the working myocardium, subendocardial Purkinje fibres do not display a higher resistance to early global ischaemia. Further investigations of this sensitivity of Purkinje fibres to global ischaemia and certain drugs may bring about new insights into myocardial protection and pharmacotherapy of arrhythmias.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01600240
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  • 4
    Electronic Resource
    Electronic Resource
    The surface to volume ratio of mitochondria, a suitable parameter for evaluating mitochondrial swelling (1990)
    Springer
    Virchows Archiv 416 (1990), S. 305-315 
    Details
    ISSN: 1432-2307
    Keywords: Myocardial ultrastructure ; Mitochondrial swelling ; Stereology ; Correlations of structural parameters ; Cardiac arrest and global ischaemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cellular changes occuring in the left ventricular myocardium during ischaemia after different methods of cardiac arrest have been evaluated by morphological and morphometric parameters: volume densities of mitochondria (VVMi), sarcoplasm (VVSp), myofibrils (VVMf), surface densities of mitochondria (SVMi). The surface to volume ratio of mitochondria (SVratioMi) has been used as an independent parameter of mitochondrial swelling. Since ischaemic swelling of myocardial cells increases the volume of the reference space and ischaemic swelling of mitochondria decreases the free sarcoplasm, VVMi and VVSp cannot be considered as reliable indicators of the degree of oedema. SVMi/VVMf remains nearly constant after different forms of cardiac arrest, demonstrating the integrity of mitochondrial outer membranes. The inverse linear ratio between SVratioMi and the mean mitochondrial volume indicates that the increase in mitochondrial volume is achieved by surface smoothing. Loss of matrix structure and fragmentation of cristae occur at an SVratioMi of about 5.8, cristolysis at 5.5 to 5.6 and amorphous matrix densities at an SVratioMi of less than 5.5 μm2/μm3. The SVratioMi is a suitable parameter for evaluating mitochondrial swelling both at the onset and during global myocardial ischaemia, independent of the method of cardiac arrest used. It serves as an indicator of the state of structural preservation of mitochondria during ischaemia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01605291
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of ischaemia and preservation on the ultrastructure of the bronchiolar epithelium (1996)
    Springer
    Virchows Archiv 429 (1996), S. 109-118 
    Details
    ISSN: 1432-2307
    Keywords: Lung-transplantation pathology ; Bronchi-epithelium ; Ischaemia ; Mitochondrial swelling ; Scanning electron microscopy ; Transmission electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In ten cases of clinical human single-lung transplantation, the nontransplanted Euro-Collins-preserved contralateral lungs were examined using electron microscopy to determine the effects of ischaemia on the bronchiolar epithelium. Existing structural damage at the time of transplantation was characterized using this approach, and nine nonpreserved canine single lungs were also investigated to identify the impact of ischaemia. The study revealed a significant correlation between the duration of ischaemia and the mitochondrial surface-to-volume ratio, which can serve as a morphometric criterion for mitochondrial damage, in canine lungs. However, this correlation was not found in the human donor lungs. Further examination of human donor lungs showed slight to moderate damage to the endoplasmic reticulum and nuclear chromatin. In addition, various degrees of damage to mitochondrial structure, ranging from inconspicuous to severe, were found. The mitochondrial surface-to-volume ratio can be considered to be a suitable criterion for the quantification of ischaemic damage of the bronchiolar epithelium under experimental conditions. Ultrastructural analysis of human donor lungs revealed intact bronchiolar epithelial cell structures at the time of transplantation, reflecting adequate organ preservation with Euro-Collins solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192433
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  • 6
    Electronic Resource
    Electronic Resource
    Quantum fluctuations in structurally disordered antiferrromagnets (1995)
    Springer
    Journal of low temperature physics 99 (1995), S. 359-361 
    Details
    ISSN: 1573-7357
    Keywords: 75.10.Jm ; 75.50.Ee ; 71.55.Jv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present exact diagonalisation data for the ground state of finite two-dimensional spin 1/2 Heisenberg antiferromagnets with structural disorder. The combination of antiferromagnetic coupling and structural disorder creates frustation and a local singlet formation which may strongly influence the magnetic ordering. In detail we study the magnetic radial distribution function, the magnetic order parameter M2 as well as a parameter measuring the spin misfit and present these quantities in dependence on the strength of the structural disorder. We estimate the critical disorder where the antiferromagnetic long-range order breaks down.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00752309
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of the ground-state wave function of theJ 1-J 2 quantum Heisenberg antiferromagnet (1993)
    Springer
    The European physical journal 93 (1993), S. 21-31 
    Details
    ISSN: 1434-6036
    Keywords: 75.10.Jm ; 75.40.Cx ; 75.50.Ee
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We investigate the ground-state wave function $$|\psi \rangle = \sum\limits_n {\alpha _n } |n\rangle $$ of the spin-1/2J 1-J 2 model on finite square lattices ofN=16(4×4) andN=24(4×6) sites. We find that the Marshall-Peierls phase rule for coefficientsα n , which was derived for unfrustrated bipartite lattices (J 2=0), holds exactly for comparably large frustration up toJ 2/J 1=0.28 (N=16) and up toJ 2/J 1=0.20 (N=24). But even for strong frustration up toJ 2/J 1≈0.45 the Marshall-Peierls rule describes the phase relationships in the ground state excellently. In the region of dominatingJ 2 a phase rule can be formulated as a product of the rules for two independent antiferromagnets. We find that the violation of the Marshall-Peierls sign rule does not dramatically affect the order parameters up toJ 2/J 1≈0.6. To calculate the magnitude of the coefficientsα n by a variational procedure we search for a represantative relationship between theα n and (a few) parametersP 1,n ...P k, n classifying the Ising basis states |n〉. By comparison with the exact ground state we analyze classification schemes based on pair correlations (Jastrow type wave functions) as well as schemes taking into account cluster parameters. While for small frustrationJ 2/J 1〈0.2 a short-range Jastrow description (nearest-neighbour and next nearestneighbour pairing) seems to be sufficient for the adequate description of the ground state one definitly needs longrange pairing and/or cluster parameters to construct a reasonable trial wave function for strong frustration. As an example for a special Jastrow type wave function we discuss an ansatz coming from the spin-wave theory. Finally, we consider the influence of the anisotropic exchangeJ zz ≠J xx ,J yy on the quality of the short-range Jastrow wave function and find and excellent agreement with the exact ground state already for Ising exchange anisotropiesJ xx =J yy ≈0.5J zz .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01308803
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  • 8
    Electronic Resource
    Electronic Resource
    Morphometric evaluation of volume shifts between intra- and extra-cellular space before and during global ischemia (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 241 (1995), S. 319-327 
    Details
    ISSN: 0003-276X
    Keywords: Heart ; Dog ; Cardioplegia ; Cardiac arrest ; Ischemia ; Morphometry ; Interstitial space ; Contraction state ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: It is well known that all forms of cardiac arrest lead to global ischemia combined with alterations in cellular and interstitial volume. The aim of this study was to investigate the nature of these alterations with respect to different methods of cardiac arrest and establish the extent of their mutual influence at the onset as well as during the course of global ischemia.Methods: Three tested clinical methods were employed to induce cardiac arrest by a) aortic cross clamping, b) coronary perfusion with the cardioplegic solution St. Thomas, and c) coronary perfusion with the cardioplegic solution histidine-tryptophane-ketoglutarate (HTK). The arrested hearts were subjected to global ischemia at 25°C. The size of the myocytes, as well as the interstitial space of myocytes, was determined morphometrically. The contraction state of myocytes was evaluated according to a score.Results: We found that the degree of contraction, as well as nature of alterations in the cellular and interstitial volumes, depended both on the form of cardiac arrest and on the duration of ischemia. The following relationships were established. High contraction at the onset of ischemia leads to expulsion of fluid from the interstitium between bundles of myocytes into the tissue clefts increasing their size. The decrease in contraction during ischemia leads to narrower tissue clefts. Cellular swelling at the onset of and during ischemia is caused by volume shifts between intracellular and interstitial space. An increase in cellular volume during global ischemia and/or additional contraction reduce the interstitium within bundles of myocytes. Sufficient relaxation and/or interstitial edema enlarge the interstitium.Conclusions: Cellular and intersticial alterations seen at the onset and during the course of ischemia are dependent upon the method of cardiac arrest. Furthermore, a considerable mutual influence is exerted by the alterations in cellular and interstitial spaces. © 1995 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092410305
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