Histology and histopathology Vol.15, nº 4 (2000)
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- PublicationOpen AccessLiver fibrosis, the hepatic stellate cell and tissue inhibitors of metalloproteinases(F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2000) McCrudden, R.; Iredale, J. P.Liver fibrosis occurs as a consequence of net accumulation of matrix proteins (especially collagen types I and III) in response to liver injury. The pathogenesis of liver fibrosis is underpinned by the activation of hepatic stellate cells (HSC) to a myofibroblast like phenotype with a consequent increase in their synthesis of matrix proteins such as interstitial collagens that characterise fibrosis. In addition to this there is increasing evidence that liver fibrosis is a dynamic pathologic process in which altered matrix degradation may also playa major role. Extracellular degradation of matrix proteins is regulated by matrix metalloproteinases (MMPS) - produced by HSC - which in turn are regulated by several mechanisms which include regulation at the level of the gene (transcription and proenzyme synthesis), cleavage of the proenzyme to an active form and specific inhibition of activated forms by tissue inhibitors of metalloproteinases (TIMPS). Insights gained into the molecular regulation of HSC activation will lead to therapeutic approaches in treatment of hepatic fibrosis in the future , and could lead to reduced morbidity and mortality in patients with chronic liver injury .
- PublicationOpen AccessGlycogen autophagy in newborn rat hepatocytes(Murcia : F. Hernández, 2000) Kalamidas, Stefanos; Kotoulas, Othon B.Glycogen autophagy in newborn rat hepatocytes was studied by using enzyme determinations and electron microscopy. Cyclic AMP induced glycogen autophagy in these cells. Glycogen-hydrolyzing acid glucosidase activity increased whereas acid mannose 6- phosphatase activity decreased in the liver of these animals. Parenteral glucose, which prevents postnatal glucagon secretion and tissue cyclic AMP elevation, and propranolol which antagonizes cyclic AMP, inhibited glycogen autophagy. Glucosidase activity decreased and phosphatase activity increased. These findings raise the possibility that cyclic AMP-induced autophagic mechanisms in newborn rat hepatocytes are associated with changes in the activity of acid mannose 6- phosphatase.
- PublicationOpen AccessTopographical difference of cytoskeletal organization in smooth muscle cells of rat duodenum revealed by quick-freezing and deep-etching method(Murcia : F. Hernández, 2000) Takayama, I.; Fuji, Y.; Terada, N.; Baba, T.; Kato, Y.; Fujino, M.A.; Ohno, S.The sarcolemmal domain of rat duodenal smooth muscle cells includes caveolae and associated cytoskeletal or filamentous elements. We have used the quick-freezing, deep-etching method to examine the three dimensional relationships between these components. Replica membranes for separated strips of rat duodenal muscle layers were routinely prepared after extraction soluble proteins from cytoplasm and extracellular matrix. As results, 1) cytoskeletal elements in smooth muscle cells consisted mainly of striated thin filaments; 2) thin filaments were connected with some plasma membranes through filaments associated with the sarcolemma, which formed fine network structures beneath the sarcolemma; 3) many bridging structures between the filaments associated with the sarcolemma and the extracellular matrix were frequently detected in the plasma membrane; and 4) compact filaments associated with the sarcolemma almost disappeared near the caveolae, and only thin filaments were anchored to their neck parts. The special arrangement of the cytoskeletal components, which is probably necessary for the intestinal motility, characterizes the topographical difference of the smooth muscle sarcolemma.
- PublicationOpen AccessConfocal evaluation of native and induced lectin binding contributes to discriminate between lingual gland glycocomponents in quail(Murcia : F. Hernández, 2000) Bondi, A.M.; Gabrielli, M.G.; Accili, Daniela; Sabbieti, M.G.; Menghi, GiovannaA confocal analysis was performed on the quail (Coturnix coturnix japonica) lingual salivary glands where the carbohydrate chains were studied by lectin histochemistry. For this purpose, appropriate FITC- and TRITC-conjugates were used for double binding also accomplished with sialidase digestion. The glycosidic components of the quail lingual salivary glands were found to be heterogeneously distributed on the different secretory structures as well as on the single secretory elements of each adenomere. The rostra1 portion of the anterior lingual gland was found to only secrete neutral glycocomponents, characterized by terminal B-galactose, N-acetylgalactosamine and fucose residues in contrast to the caudal portion that was shown to be extremely heterogeneous and to produce sialylated glycoconjugates characterized by the terminal sequences sialic acid-B-galactose-N-acetylgalactosamine, sialic acid-13-galactose-N-acetylglucosamine,a nd sialic acida- N-acetylgalactosamine partly codistributed within secretory adenomeres. The posterior lingual gland was observed to be the major contributor to the secretion of salivary mucins containing sialoglycoconjugates with terminal sialic acid residues linked to B-galactose-Nacetylgalactosamine or a-N-acetylgalactosamine often located in distinct secretory elements.
- PublicationOpen AccessAge-related morphometric changes in the pineal gland. A comparative study between C57BLI6J and CBA mice(Murcia : F. Hernández, 2000) Cernuda-Cernuda, R.; Huerta, J.J.; Muñoz Llamosas, M.; Alvarez-Uría, M.; García-Fernández, J.M.Relatively little is known about the effects of melatonin on the aging of the pineal, the organ which is the main place for synthesis of this hormone. Using simple morphometric methods, some parameters of the pineal gland, such as total volume, number of pinealocytes and pinealocyte volume were estimated in two mice strains: normal CBA and melatonin-deficient C57BLl6J. Two age groups, 6 weeks and 10 months, were studied in order to evaluate possible differential age-related changes between both strains. Pineals of both strains have similar morphometric and morphological features at 6 weeks of age. This suggests that pineal development, which has already concluded at 6 weeks of age, is not affected by the absence of melatonin synthesis in the pinealocytes. Later on, CBA pineal showed an increase in size caused by cellular hypertrophy. In contrast, the C57BLl6J pineal volume decreased by loss of pinealocytes in the same period of time. Semithin sections analysed by light microscopy did not show that this cell death was evident in the C57BL16J strain at any of the ages studied. Thus, a gradual loss of pinealocytes could be hypothesised in these pineals. These results suggest that pineal melatonin could have a role in the maintenance of pinealocyte viability and the increase of pineal size which takes place after development. The abnormal pattern observed in the C57BL16J pineal should be taken into account in future studies on this gland.