Histology and histopathology Vol.15, nº 3 (2000)
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- PublicationOpen AccessApoptosis regulating genes in neuroendocrine tumors(F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2000) Liu, W.-H.; Wang, D.-G.Neuroendocrine turnors (NETs) are a heterogeneous group of neoplasms. They are relatively uncommon and characterised by a relatively indolent clinical course. The indolent nature of NETs has long been enigmatic and recent advances in apoptosis research have led to speculation regarding the role of programmed cell death in NET tumorigenesis. It is hoped that a fundamental molecular understanding will help explain these variant behaviors that are so evident to the clinician, and ultimately yield novel and more effecti ve therapies. Recent studies have demonstrated that deregulation of programmed cell death may be a critical component in the multistep tumorigenesis of NETs and that the frequent expression of the BCL-2 oncoprotein in these tumors may contribute to their pathogenesis. The genetic complementation of simultaneously deregulated BCL-2 and c-MYC may be implicated in the multistep tumorigenesis of human NETs. It is also clear that numerous cellular gene products can and will be shown to impact upon apoptosis in NETs; some of these may even be molecules identified as oncoproteins or tumor suppressors. The major challenge will be to ascribe primary pathogenetic significance to tumor-associated derangements in expression of these molecules, and hopefully to then exploit our knowledge toward therapeutic benefit.
- PublicationOpen AccessMechanisms underlying eosinophil trafficking and their relevance in vivo(F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2000) Cara, D. C.; Negrao-Correa, D.; Teixeira, M. M.After their formation in the bone marrow, eosinophils circulate with a short half-life and are distributed throughout the body, especially in mucosal and sub-mucosal regions. Although a small amount of these cells are normally seen in healthy tissue, blood and tissue eosinophilia is a hallmark of helminthic and allergic diseases. The role of eosinophils in the normal physiology of mucosal tissues is not understood, but there is good evidence to demonstrate that these cells protect the host at least against some intestinal helminths, specially those with a lung cycle. In addition, there are now many data that support a role for eosinophils in the pathophysiology of allergic diseases, such as asthma. Because helminthic diseases have been largely controlled in developed countries, there has been much interest in the development of drugs which affect eosinophil migration and/or activation in the tissue and which may, thus, be useful in the treatment of allergic conditions. The understanding of the mechanisms controlling eosinophil trafficking and/or activation are essential in the development of anti-eosinophil-based therapeutic strategies. The present paper reviews aspects of eosinophil biology with emphasis on the role of eosinophils in parasitic infections and allergy, the basic mechanisms underlying the trafficking of eosinophils into tissue and how these can be modulated pharmacologically.
- PublicationOpen AccessThe distribution of cholinergic neurons in the human central nervous system(F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2000) Oda, Y.; Nakanishi, I.Choline acetyltransferase (ChAT), the enzyme responsible for the biosynthesis of acetylcholine, is presently the most specific marker for identifying cholinergic neurons in the central and peripheral nervous systems. The present article reviews immunohistochemical and in situ hybridization studies on the distribution of neurons ex pressing ChAT in the human central nervous system. Neurons with both immunoreactivity and in situ hybridization signals of ChAT are observed in the basal forebrain (diagonal band of Broca and nucleus basalis of Meynert), striatum (caudate nucleus, putamen and nucleus accumbens), cerebral cortex, mesopontine tegmental nuclei (pedunculopontine tegmental nucleus, laterodorsal tegmental nucleus and parabigeminal nucleus), cranial motor nuclei and spinal motor neurons. The cerebral cortex displays regional and laminal differences in the distribution of neurons with ChAT. The medial seotal nucleus and medial habenular nucleus contain immunoreactive neurons for ChAT, which are devoid of ChAT mRNA signals. This is probably because there is a small number of cholinergic neurons with a low level of ChAT gene expression in these nuclei of human. Possible connections and speculated functions of these neurons are briefly summarized.
- PublicationOpen AccessImmunopathology of autoimmune gastritis: Lessons from mouse models(F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2000) Alderuccio, F.; Toh, B. H.Autoimmune gastritis in humans is a chronic inflammatory disease of the stomach accompanied by specific destruction of gastric parietal and zymogenic cells resulting in pernicious anemia. Human gastritis can be accurately reproduced in mice and is characterised by autoantibodies to the a- and B-subunits of the gastric H/K ATPase (the enzyme responsible for gastric acid secretion) and cellular destruction of parietal and zymogenic cells within the gastric gland. Studies with these mouse models have given us our current concepts of the immunopathogenesis of the gastritis. Mouse models have shown that a T cell response is generated to the a- and B-subunits of the H/K ATPase and that an immune response to the B-subunit seems to be required for disease initiation. Using these models, we have defined key events associated with a damaging autoimmune response to the gastric H/K ATPase. The mechanisms associated with the cellular destruction associated with autoimmune gastritis are not know, but may involve signaling through death inducing pathways such as the Fas/FasL and TNF/TNFR pathways. This knowledge should permit us to develop strategies to prevent and treat the gastritis.
- PublicationOpen AccessMast 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.