Histology and histopathology Vol.13, nº 3 (1998)
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- PublicationOpen AccessEndothelin-l enhances thymocyte proliferation in monolaterally adrenalectomized rats with contralateral adrenocortical regeneration(Murcia : F. Hernández, 1998) Malendowicz, L.K.; Macchi, Verónica; Brelinska, R.; Trejer, M.; Gottardo, Giuseppe; Nussdorfer, G.G.Endothelins (ETs) are a family of vasoactive peptides widely distributed in the body systems, where they exert pleiotropic biological effects, acting through two main subtypes of receptors, named ETA and ETB. Evidence indicates that ET-1 plays a permissive role in the development of neural crest-derived structures, among which are the epithelia1 cells of the thymus. These cells are known to control proliferation and differentiation of thymocytes, a process requiring adequate levels of glucocorticoids. Therefore, we have investigated the effects of ET-1, that binds both ETA and ETB receptors, on thymocyte proliferation in monolaterally adrenalectomized rats with contralateral enucleated adrenal at day 4 and 8 of regeneration, when glucocorticoid production is very low and, respectively, rather normal. Metaphase index (percentage of metaphase arrested cells) of thymocytes is the lowest at day 4 of regeneration, and markedly rose at day 8, thereby confirming the need of sizable levels of circulating glucocorticoid for the maintenance of a normal rate of thymocyte proliferation. ET-l markedly increased the mitotic index of thymocytes at both times of adrenal regeneration. At day 8 of regeneration, the ETA-receptor antagonist BQ-123 markedly lowered mitotic index of thymocytes, and annulled its ET-1- evoked raise. Conversely, the ETB-receptor antagonist BQ-788 was ineffective. Collectively, these findings clearly indicate that endogenous ETs, through the activation of ETA receptors, are involved in the maintenance and stimulation of thymocyte proliferation in the adult rat, thereby playing a possibly important role in the modulation of the immune-system functions.
- PublicationOpen AccessHistochemical study of skin and gills of Senegal sole, Solea senegalensis larvae and adults(Murcia : F. Hernández, 1998) Sarasquete, C.; Gonzalez de Canales, M.L.; Arellano, J.M.; Muñoz Cueto, J.A.; Ribeiro, L.; Dinis, M.T.A battery of horseradish peroxidaseconjugated lectins (Con A, WGA and DBA), as well as conventional histochemical techniques (PAS, saponification, Alcian Blue pH 0.1, 1, 2.5, chlorhydric hydrolisis, neuraminidase, Bromophenol blue, Tioglycollate reduction and Ferric-ferricyanide-FeIII) were used to study the content and distribution of carbohydrates, proteins and glycoconjugate sugar residues on the skin and gills of Senegal sole, Solea senegalensis larvae and adults. During larval development of Solea senegalensis (from hatching until day 45 posthatching), epidermal sacciform, as well as branchial and epidermal chloride cells were unreactive with all cytochemical tests performed in this paper. Mucous or goblet cells of the corporal skin and gills containing strongly sulphated acid glycoproteins were evident on days 15-20 of larval development, as well as in epidermal and branchial mucous cells of adult specimens, which also contained GlcNAc andlor sialic acid. In adult specimen, the proteic content was higher in branchial mucous cells than in epidermal cells. In larvae, variable amounts of glycoproteins containing sialic acid, GlcNAc, GalNAc, Man andlor Glc residues were observed in epithelia1 cells and/or cuticle. GlcNAc andlor sialic acid sugar residues were only weakly detected in glycoproteins of some epidermal and branchial mucous cells of larvae by day 45, because from hatching until metamorphosis, lectin reactions (WGA, Con A and DBA) were negative in mucous cells.
- PublicationOpen AccessLiver cell dysplasia: reactivities for c-met protein, Rb protein E-cadherin and transforming growth factor-01 in comparison with hepatocellular carcinoma(Murcia : F. Hernández, 1998) Zhao, M.; Zimmermann, AstridIn the present retrospective study, liver cell dysplasia (LCD) occurring in cirrhotic livers associated or not associated with hepatocellular carcinoma (HCC) was immunohistochemically analyzed for the expression of hepatocyte growth factor receptor (c-met protein), Rb (retinoblastoma gene) protein, E-cadherin, and transforming growth factor-B-l (TGF-B-1). Cytoplasmic cmet protein staining was observed in about half of the HCC's, and its prevalence was about twice as high in high grade vs. low grade tumors, but it was not correlated with proliferative activity as based on PCNA labelling. In LCD, reactivity for c-met protein was restricted to the small cell type. Nuclear staining for Rb protein was found in HCC's, and was not related to type, grade or proliferative activity, whereas no immunoreactivity was observed in normal, hyperplastic or dysplastic hepatocytes. Expression of E-cadherin prevailed in HCC's of lower grade, and particularly in those with a trabecular or acinar growth pattern. Ecadherin staining was detectable in normal and large dysplastic hepatocytes, but not in small dysplastic liver cells. TGF-B-1 reactivity was observed in more than half the HCC's, but not in normal or dysplastic hepatocytes. These findings underline the phenotypic difference between large cell and small cell liver dysplasia, and support the hypothesis that small cell dysplasia is a precursor lesion in a hepatocarcinogenic pathway.
- PublicationOpen AccessImportance of interfacial water in permeabilization of ceramide bilayers(Murcia : F. Hernández, 1998) Neitchev, V.; Kostova, E.; Dimitrov, A.S.The role of structured water at the membrane- aqueous interface in regulating the water permeability functions of the epidermal horny layer (Stratum corneum) is not clear at present. The subject of this review is the effect of perturbed interfacial water structure on the relative water permeability properties in shrinkage experiments of reconstituted vesicle suspensions of ceramides and cholesterol in the gel phase. Water structure was perturbed by a series of reagents known to affect the phase equilibrium of lipid assemblies. Multilamellar bilayers containing synthetic ceramides N-palmitoyl-D-L-dihydrosphingosine, and Noleoyl- D-sphingosine were used as model membranes. The reagent binding to the ceramide membrane was determined by fluorescence measurements with 1- anilino, 8-naphtalene sulphonate (ANS). A dependence of number of binding sites for ANS on the type of reagent was found. The change of relative water permeability with concentration of reagents was studied. Analysis of these data reveals that the anomalous behaviour of relative water permeability with the concentration of reagents used is due to concentrationdependent structural transitions of the bound water at the membrane-aqueous interface. Different possibilities of interaction of the reagents with the interface are discussed. At the end, it is suggested that the interfacial water in multilamellar ceramide structures may also contribute to the water holding and permeability barrier functions of cell membrane complex within the stratum corneum.
- PublicationOpen AccessGenetics and pathology of voltage-gated ca2+ channels(Murcia : F. Hernández, 1998) Ophoff, R.A.; Terwindt, G.M.; Ferrari, M.D.; Frants, R.R.Neurotransmitter release, neuronal excitation, and a whole variety of other neuronal functions are controlled by the intralextra cellular ca2+ gradient. The major pathway for entry of ca2+ into the excitable cells is mediated by voltage-gated ca2+ channels. Several functional subclasses of voltage-dependent ca2+ channels have been identified, based on their pharmacological, biophysical properties, and molecular cloning. Recently, three human diseases (familial hemiplegic migraine, episodic ataxia type 2, and spinocerebellar ataxia 6) were added to the growing list of ion-channel disorders, all caused by different mutations in the P/Qtype ca2+ channel a1 subunit. Molecular analysis of the ca2+ channelopathies will provide new insights into the role, function and pathology of these voltage-gated ca2+ channels.