Browsing by Subject "Fixation"

Now showing 1 - 3 of 3
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    Assessment of murine brain tissue shrinkage caused by different histological fixatives using magnetic resonance and computed tomography imaging
    (F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2015) Wehrl, Hans F.; Bezrukov, Ilja; Wiehr, Stefan; Lehnhoff, Mareike; Fuchs, Kerstin; Mannheim, Julia G.; Quintanilla-Martine, Leticia; Kohlhofer, Ursula; Kneilling, Manfred; Pichler, Bernd J.; Sauter, Alexander W.
    Especially for neuroscience and the development of new biomarkers, a direct correlation between in vivo imaging and histology is essential. However, this comparison is hampered by deformation and shrinkage of tissue samples caused by fixation, dehydration and paraffin embedding. We used magnetic resonance (MR) imaging and computed tomography (CT) imaging to analyze the degree of shrinkage on murine brains for various fixatives. After in vivo imaging using 7 T MRI, animals were sacrificed and the brains were dissected and immediately placed in different fixatives, respectively: zinc-based fixative, neutral buffered formalin (NBF), paraformaldehyde (PFA), Bouin-Holland fixative and paraformaldehyde-lysine-periodate (PLP). The degree of shrinkage based on mouse brain volumes, radiodensity in Hounsfield units (HU), as well as non-linear deformations were obtained. The highest degree of shrinkage was observed for PLP (68.1%, P<0.001), followed by PFA (60.2%, P<0.001) and NBF (58.6%, P<0.001). The zinc-based fixative revealed a low shrinkage with only 33.5% (P<0.001). Compared to NBF, the zinc-based fixative shows a slightly higher degree of deformations, but is still more homogenous than PFA. Tissue shrinkage can be monitored non-invasively with CT and MR. Zinc-based fixative causes the smallest degree of brain shrinkage and only small deformations and is therefore recommended for in vivo ex vivo comparison studies.
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    Mast cell granule composition and tissue location - a close correlation
    (F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2000) Beil, W. J.; Schulz, M.; Wefelmeyer, U.
    This review provides a survey on mast cell heterogeneity, with aspects differing in humans and rodents or which are subject of conflicting evidence being discussed in greater detail. Mast cell subsets have been first defined in rats by their fixation and dyebinding properties, and detailed studies in humans and pigs reveal very similar observations. The dye-binding properties of rat mast cell subsets are causally related to the absence or presence of heparin in their granules. In humans, this relation has not been shown. Rodent mast cell subsets store different chymase-isoforms. In contrast, just a single chymase has been defined in humans, and mast cells are classified by the presence or relative absence of this chymase. Different investigators find quite different proportions of chymase-positive to chymase-negative mast cells. Tryptase(s) are found in most or every human mast cell, but in rodents, they have hitherto been essentially localised to mast cells in connective tissues. Human mast cell subsets may also be defined by their expression of receptors such as CSaR and possibly the B-chemokine receptor CCR3; the CCR3 expression seems to be related to the human mast cell chymase expression. Ultrastructural studies are helpful to distinguish human mast cell subsets, and allow to distinguish between chronic and acute activation. The phenotypical characteristics may change in association with inflammation or other disease processes. Studies in humans and pigs show changed dye-binding and fixation properties of the granules. Experimental rodent infection models reveal similar changes of chymase isoform expression. Human lung mast cells have been reported to strongly upregulate their chymase content in pulmonary vascular disease. This line of evidence can explain some inconsistent information on mast cell heterogeneity and may help to understand the physiological role of mast cells.
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    Origin and Dismeasure: the Thought of Sexual Difference in Luisa Muraro and Ida Dominijanni, and the Rise of Post-Fordist Psychopathology
    (Universidad Complutense de Madrid, 2013) Righi, Andrea
    In Pensiero Vivente (2010), Roberto Esposito investigates the issue of origin as a crucial axis of inquiry for Italian philosophy. His acute reconstruction of Italian philosophical thought, however, dedicates little attention to feminism and to the philosophies of those who carry out the labor of procreation and reproduction. This essay reframes the problem of origin from the point of view of the maternal, exploring the thought of sexual difference in the work of two prominent militants of the Diotima philosophical Community: Luisa Muraro and Ida Dominijanni. The aim is twofold: study how the notion of the maternal symbolic can be understood as furthering Jacques Lacan’s construction of the feminine; show how the socio-psychological transformations produced by post-Fordism call for a rethinking of some of the basic assumptions of the maternal symbolic, particularly the notion of fixation.