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  • 1995-1999  (6)
  • 1980-1984  (7)
  • 1
    Electronic Resource
    Electronic Resource
    Ectopic mineralized cartilage formation in human undifferentiated pancreatic adenocarcinoma explants grown in nude mice (1995)
    Springer
    Calcified tissue international 56 (1995), S. 145-153 
    Details
    ISSN: 1432-0827
    Keywords: Ectopic cartilage formation ; Chondrocyte ; Differentiation ; Pancreatic cancer ; Mincralization ; Nude mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Mineralized as well as nonmineralized cartilage-like structures enclosing cells resembling chondrocytes were found in human-derived undifferentiated but not in poorly differentiated pancreatic adenocarcinoma explants grown in nude mice. The structures reacted with anti-mouse IgG but not with antibodies against human cytokeratin 19, indicating that the newly formed tissue was of mouse origin. High activity of alkaline phosphatase was found in cell layers surrounding the structures and in cells embedded in the matrix. The extracellular matrix was strongly positive after Sirius red staining, reacted with anti-collagen type II antibodies, and the presence of proteoglycans was demonstrated with Alcian blue staining and by metachromasia after Giemsa staining. Electron microscopic inspection revealed the presence of bundles of both thick collagenous fibrils with low levels of fine filamentous material and thin collagenous fibrils with high concentrations of filamentous components. The majority of both types of matrices was found to be partially or completely calcified. The mean area density of the cartilage-like structures in the undifferentiated tumors was 0.31%. The frequent formation of the cartilage-like structures in the rapidly growing undifferentiated explants and its absence in the slowly growing, more differentiated explants suggest that low oxygen tensions in combination with altered levels of growth factors, such as members of the transforming growth factor β superfamily, create conditions that induce differentiation of fibroblasts to chondrocytes. It is concluded that these human tumors grown in nude mice can be used as an in vivo model to study ectopic formation of mineralized cartilage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296347
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  • 2
    Electronic Resource
    Electronic Resource
    A new method for the enzyme cytochemical staining of individual cells with the use of a polyacrylamide carrier (1982)
    Springer
    Histochemistry and cell biology 74 (1982), S. 171-181 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A new method for enzyme cytochemical studies on individual cells is developed. Cells are incorporated in the matrix of a thin film of transparent polyacrylamide prior to incubation in a cytochemical medium. Five different kinds of individual cells, i.e. isolated rat hepatocytes, isolated mouse oocytes, cultivated human fibroblasts, rat thymocytes and human blood cells are used for testing the applicability of this method for the cytochemical demonstration of glucose-6-phosphate dehydrogenase with tetranitro BT. The incorporation technique solves at least some of the problems occurring with enzyme cytochemistry on single cells. The morphology of the cells is very well preserved, the formazan precipitation due to enzyme activity occurs entirely within the cell cytoplasm, the nothing dehydrogenase activity can be kept very low and the loss of cells is completely prevented with all cell types used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00495828
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Heterogeneity of kinetic parameters of enzymes in situ in rat liver lobules (1995)
    Springer
    Histochemistry and cell biology 103 (1995), S. 93-101 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In the present review, metabolic compartmentation in liver lobules is discussed as being dynamic and more complex than thus far assumed on the basis of numbers of mRNA or protein molecules or the capacity (zero-order activity) of enzymes. Isoenzyme distribution patterns and local kinetic parameters of enzymes may vary over the different zones of liver lobules. As a consequence, metabolic fluxes in vivo at physiological substrate concentrations may be completely different from those that are assumed on the basis of the number of molecules or the capacity of enzymes present in zones of liver lobules. For a more correct estimation of the levels of metabolic processes in the different compartments of liver tissue, local kinetic parameters and substrate concentrations have to be determined to calculate local metabolic fluxes. direct measurements of metabolic fluxes in vivo with the use of noninvasive techniques is a promising alternative and the techniques will become increasingly important in future metabolic research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01454005
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  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of activity of phosphatases by low temperature incubation of unfixed cryostat sections (1996)
    Springer
    Histochemistry and cell biology 106 (1996), S. 351-355 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  In the present study, we demonstrate the activity of several phosphatases ultrastructurally in long-term (up to 24 months) cold-stored (−80° C) rat tissues. Phosphatase activity was histochemically studied with the use of unfixed cryostat sections in combination with low temperature (4° C) incubation conditions in order to prevent inactivation of enzyme activity and to limit the loss of ultrastructure. 5′-Nucleotidase activity was observed at plasma membranes, mainly at bile canalicular membranes of hepatocytes in liver. Thiamine pyrophosphatase activity was detected not only in trans side cisternae but also in medial and cis side cisternae of Golgi complexes in the parotid gland. Glucose-6-phosphatase activity was localized in endoplasmic reticulum as well as at the outer membrane of the nuclear envelope. Acid phosphatase reaction product was found in lysosomes. Furthermore, the localization patterns of 5′-nucleotidase and thiamine pyrophosphatase activity were compared with those obtained after different fixation procedures such as immediate chemical fixation of tissues or fixation of tissues after freezing and thawing. The results showed similar localization patterns of these enzymes after the different pretreatments. However, with respect to the ultrastructural morphology, some damage was observed in unfixed material after incubation. It can be concluded that the procedure described here enables ultrastructural localization of activity of phosphatases in long-term cold-stored tissues. This procedure will be useful for a retrospective study on archival material when histochemical parameters are needed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050051
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of activity of phosphatases by low temperature incubation of unfixed cryostat sections (1996)
    Springer
    Histochemistry and cell biology 106 (1996), S. 351-355 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In the present study, we demonstrate the activity of several phosphatases ultrastructurally in long-term (up to 24 months) cold-stored (−80°C) rat tissues. Phosphatase activity was histochemically studied with the use of unfixed cryostat sections in combination with low temperature (4° C) incubation conditions in order to prevent inactivation of enzyme activity and to limit the loss of ultrastructure. 5′-Nucleotidase activity was observed at plasma membranes, mainly at bile canalicular membranes of hepatocytes in liver. Thiamine pyrophosphatase activity was detected not only intrans side cisternae but also in medial andcis side cisternae of Golgi complexes in the parotid gland. Glucose-6-phosphatase activity was localized in endoplasmic reticulum as well as at the outer membrane of the nuclear envelope. Acid phosphatase reaction product was found in lysosomes. Furthermore, the localization patterns of 5′-nucleotidase and thiamine pyrophosphatase activity were compared with those obtained after different fixation procedures such as immediate chemical fixation of tissues or fixation of tissues after freezing and thawing. The results showed similar localization patterns of these enzymes after the different pretreatments. However, with respect to the ultrastructural morphology, some damage was observed in unfixed material after incubation. It can be concluded that the procedure described here enables ultrastructural localization of activity of phosphatases in long-term cold-stored tissues. This procedure will be useful for a retrospective study on archival material when histochemical parameters are needed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02473245
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  • 6
    Electronic Resource
    Electronic Resource
    A sensitive cytochemical staining method for glucose-6-phosphate dehydrogenase activity in individual erythrocytes (1982)
    Springer
    Histochemistry and cell biology 75 (1982), S. 493-506 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A sensitive cytochemical staining method for glucose-6-phosphate dehydrogenase activity in individual human erythrocytes is described. This staining method can be used for the rapid routine discrimination of patients with a deficiency of the enzyme in its homozygote or heterozygote form, but also for quantitative localization of its activity in individual erythrocytes. The staining procedure in its optimal form consists of a treatment of the erythrocytes with sodium nitrite, then a “fixation” in 0.025% glutaraldehyde (under NADP+ protection of the active site of the enzyme), followed by incubation of the cells in suspension in the presence of tetranitro BT, 1-methoxyphenazine methosulphate and polyvinyl alcohol. Using this new technique, a sharp localization is obtained of the glucose-6-phosphate dehydrogenase activity, which enables discrimination between red cells with different levels of enzyme activity, as a consequence of enzyme deficiencies or age changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00640601
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  • 7
    Electronic Resource
    Electronic Resource
    Quantitative aspects of the cytochemical demonstration of glucose-6-phosphate dehydrogenase with tetranitro BT studied in a model system of polyacrylamide films (1980)
    Springer
    Journal of molecular histology 12 (1980), S. 669-685 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cytochemical determination of the activity of glucose-6-phosphate dehydrogenase (G6PDH) with tetranitro blue tetrazolium (TNBT) was studied with model films of polyacrylamide gel incorporating purified enzyme. This model system enabled a quantitative study to be made of different parameters involved with the cytochemical assay as it is applied to sections or smears. The enzyme activity of G6PDH incorporated in the model films was also assayed biochemically. Optimal conditions for retaining the maximum amount of enzymic activity are described. The behaviour of G6PDH towards enzyme inhibitors was found to be similar in model films and in solution. With TNBT, absorbance measurements at a single wavelength (535 nm) were used to estimate the enzyme activity quantitatively. When carried out under standardized conditions, both the cytochemical and biochemical assay showed a linear relation with the time of incubation and obeyed the Beer-Lambert law. The correlation between biochemical and cytochemical data was very high, which enabled cytochemical data to be converted into absolute units of enzyme activity. The data obtained in this way closely resembled the data of enzyme activity calculated from the absorbance of formazan produced inside polyacrylamide model films and afterwards extracted into a suitable solvent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01012022
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  • 8
    Electronic Resource
    Electronic Resource
    Advantages of 1-methoxyPMS as an electron carrier in dehydrogenase cytochemistry (1982)
    Springer
    Journal of molecular histology 14 (1982), S. 837-842 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01033632
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  • 9
    Electronic Resource
    Electronic Resource
    Sensitivity to light of solutions of phenazine methosulphate (1983)
    Springer
    Journal of molecular histology 15 (1983), S. 275-276 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01006242
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  • 10
    Electronic Resource
    Electronic Resource
    Model film studies in enzyme histochemistry with special reference to glucose-6-phosphate dehydrogenase (1981)
    Springer
    Journal of molecular histology 13 (1981), S. 187-206 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This paper deals with the progress made over the last few years in our understanding of enzyme cytochemical staining methods as studied using a fundamental approach with the aid of a model system of thin gel films. Although model films with a matrix of polyacrylamide have been mostly used, the properties and possible applications of other matrices are also reviewed. The chemical aspects of the entrapment of enzyme molecules into a matrix are summarized. Special attention has been paid in model film studies to the principles of the trapping reaction of a diffusable precursor resulting from the enzymatic conversion of a substrate. They are considered here as they concern the cytochemical demonstration of acid phosphatase activity with a lead salt. The effect of fixatives on different enzyme activities, the diffusion rate of substrates and chromogenic compounds to the enzyme site, and enzyme kinetics under cytochemical conditions are also discussed, since they are factors which influence the final results of the staining procedures. The advantage of model film studies in enabling the direct correlation of cytochemical and biochemical results is outlined with special reference to the cytochemical determination of glucose-6-phosphate dehydrogenase with Tetra Nitro BT. A method for determining enzyme activities in the soluble fraction of isolated cells after incorporation in model films is described for the first time. This method has proved to be highly appropriate for microscopical observations of glucose-6-phosphate dehydrogenase activity in single cells, because it results in a good morphology and no formazan precipitaties outside the cells. On the other hand, this type of model film forms a bridge between fundamental model film studies using purified enzyme and quantitative enzyme cytochemistry performedin situ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01006879
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