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D Neves

Publications and source records attributed to D Neves.

7 recordsLinked to original sources
PubMed2000

Poly-A-rich domains in adrenal cell nuclear matrix after acute and chronic ACTH stimulation: an in situ hybridization study.

The regulatory effects of adrenocorticotropin (ACTH) at the adrenal cell nucleus are not yet completely clarified. Recent studies showed that eukaryotic cell nucleus is composed of specific subcompartments organized by the nucleoskeleton-nuclear matrix. In this paper, the RNA polymerase II transcriptional domains were detected in the adrenal nucleus after acute and chronic ACTH stimulation by using in situ hybridization. Polydeoxythymidine (poly-T) probe, complementary to the polyadenylated (poly-A) chain of all the mRNAs and its precursors, was used. Hybridization was performed in intact adrenal cells and in nuclear matrices isolated from previously dispersed cells. The transcriptional domains, enriched in poly-A RNA, were evident in intact adrenal cells, the staining intensity being higher both in the acutely and in the chronically stimulated animals. In the nuclear matrices poly-A-rich areas were still visible, and were more intensely stained after ACTH stimulation.

Adrenal Glands↗
PubMed1999

Effects of prolonged infusion of basic fibroblast growth factor and IGF-I on adrenocortical differentiation in the autotransplanted adrenal: an immunohistochemical study.

Adrenocortical regeneration after adrenal autotransplantation provides a model for the study of local autocrine/paracrine mechanisms involved in the growth and differentiation of the adrenal cortex. To study the possible involvement of some growth factors, namely basic fibroblast growth factor (bFGF, FGF-2) and insulin-like growth factor I (IGF-I), in cell differentiation, immunohistochemical and ultrastructural studies were carried out on adrenal autotransplants in adult male rats. To distinguish between fasciculata and glomerulosa-like cells with accuracy, tissue sections were immunostained with IZAb, which recognizes the inner zone antigen (IZAg) present in fasciculata and reticularis cells but absent from the glomerulosa, and by electron microscopy. IGF-I-treated animals exhibited a clear glomerulosa-like zone that was devoid of IZAb immunostaining. In this outer subcapsular area, ultrastructural examination showed cells containing mitochondria with irregular cristae resembling those of the fetal or immature glomerulosa cells. In contrast, no significant morphological differences were observed in bFGF-treated animals when compared with those from saline-treated controls, in both of which, IZAb immunostaining occurred in almost all adrenocortical cells, with no clear zonation or glomerulosa, as seen in the intact animal. Plasma aldosterone and corticosterone concentrations were lower in autotransplanted control animals than in intact controls, although plasma renin activities were similar. IGF-I treatment significantly increased aldosterone concentrations, whereas corticosterone and plasma renin activity were reduced. bFGF infusion further reduced plasma aldosterone, although plasma renin activity and corticosterone were unaffected. These results suggest that the two growth factors have different effects on zonal differentiation and function in the autotransplanted gland. In particular, bFGF, by reducing glomerulosa function, appears partly to replicate the actions of ACTH in normal animals. In contrast, IGF-I enhances the glomerulosa secreting phenotype and diminishes that of the fasciculata/reticularis, possibly replicating the actions of angiotensin II or a low sodium diet.

Adrenal Cortex↗
PubMed1999

Immunocytochemical detection of structural and regulatory proteins in rat adrenal nuclear matrix.

The nuclear matrix is a specific cell structure consisting of a residual nucleoskeleton that extends from the nucleoli to the nuclear envelope. The nuclear matrix of steroidogenic cells was isolated previously from a purified nuclear fraction. We present here an in situ extraction method, modified Lutz's method, for rat glandular adrenal cell nuclear matrix. This residual organelle was characterized and studied using immunocytochemical methods. The adrenal glands were removed, the cells prepared in suspension and deposited by cytospin onto Poly-L-lysine glass slides. The nuclear matrix was extracted with Nonidet P-40, DNase I and high and low ionic strength buffers. Structural proteins, nuclear lamins, coilin and fibrillarin were detected immunocytochemically. The adrenal fasciculata cells were easily identified by this method because of their large nuclei and abundant lipid droplets in the cytoplasm. After immunocytochemical detection by antibodies against lamins A and C, a marked brown layer at the periphery of the nucleus was observed. The intensity of the staining was lower using the antibody against nuclear lamin B. Immunocytochemical detection of the protein coilin revealed punctuated stained areas, 2-6 per nucleus, that probably correspond to the coiled bodies. The protein fibrillarin was detected at the nucleolus and coiled bodies. Our technique is simple, reveals well preserved adrenal nuclear matrices, and may be a useful method for immunocytochemical analysis and in situ hybridization.

Adrenal Glands↗
PubMed1996

Modulation of autotransplanted adrenal gland by endothelin-1: a morphological and biochemical study.

BACKGROUND: Adrenal gland autotransplantation, a model of cortical tissue regeneration, provides the reconstruction of distinct functional and morphological zonae. A morphological and biochemical study of the adrenal gland of adult male rats after autotransplantation and endothelin-1 (ET-1) administration was made. METHODS: The technique involved bilateral adrenalectomy and placement of pieces of the adrenal gland in a dorsal plane between the skin and muscle. The animals were killed 90 days after the autotransplantation and 1 hr after intravenous ET-1 administration (0.5 microgram/kg body weight). The autotransplanted pieces were removed, fixed, and processed for light and electron microscopic morphologic studies. Trunk blood was collected for steroid assay. RESULTS: Saline-treated control autotransplanted animals showed no remarkable differences in adrenal organization; grafts exhibiting a mass of regenerated cortical tissue were arranged in nests of glandular cells surrounded by a fibrous capsule and intersected by layers of connective tissue. The adrenal medulla was systematically absent. Ultrastructure of ET-1-treated animals revealed an inner area in the graft, consisting mainly of fasciculatalike cells. Cytoplasmic changes were evident, with high variations in mitochondrial size and arrangement. Profiles of smooth endoplasmic reticulum sometimes exhibited evidence of hypertrophy. Glandular cells in the graft outer area (subcapsular) were almost invariably like glomerulosa; however, some of them showed mitochondria with a peculiar arrangement of the cristae. "Hybrid" cells with mitochondria resembling those of the zona reticularis were also observed in the subcapsular environment. ET-1-stimulated animals showed significant increases in plasma corticosterone and aldosterone concentrations. CONCLUSIONS: Endothelin-1, previously reported to stimulate acutely the aldosterone secretion by the adrenal zona glomerulosa in the rat, seems to exert a modulator role on the physiology of adrenal autotransplants, their regeneration and secretion.

Adrenal Glands↗
PubMed1996

New insights into zonal differentiation of adrenal autotransplants in the rat: an immunohistochemical study.

Adrenal gland autotransplantation, an interesting model of adrenal regeneration, provides the reconstruction of distinct functional and morphological zonae. An immunohistochemical study of the adrenal gland of adult male rats after autotransplantation and endothelin-1 (ET-1) stimulation was carried out. The technique involved total adrenalectomy and immediate autotransplantation of small adrenal pieces under the skin of the dorsal region. The animals were killed 90 days after the autotransplantation and 1 h after intravenous ET-1 administration. Sections of recovered adrenal grafts were incubated with IZAb, a monoclonal antibody which interacts with an antigen (IZAg) predominantly found in rat adrenal inner zones. Saline-treated control autotransplanted animals showed IZAb immunostaining in almost all adrenocortical tissue, with the exception of small clusters of cells beneath the capsule. ET-1-treated animals exhibited an extended zone devoid of immunostaining and located in the subcapsular area. In addition, ET-1-stimulated animals showed significant increases in aldosterone as well as corticosterone concentrations in plasma. These results revealed that ET-1 stimulated the development of an extended subcapsular zone lacking IZAg expression, an effect that suggests its role in zona glomerulosa induction in these animals.

Adrenal Glands↗
PubMed1993

Adrenal nuclear matrix isolation. A morphologic and biochemical study.

The nuclear matrix of adrenal cells was isolated by using the methods proposed by Commerford et al and Kaufmann et al for the liver nuclear matrix isolation. Both methods permitted, to the best of our knowledge for the first time, to prepare the nuclear matrix of a steroidogenic cell and therefore to study some regulatory mechanisms governing steroidogenesis. Commerford et al's method retains nuclear envelope and so produces a higher contamination; Kaufmann et al's method presents a higher purity since the nuclear envelope was removed by Triton X-100. No RNase digestion has been employed for the isolation of the residual nuclear matrices. Both methods however, permit the isolation of fractions with a good morphology, retaining a reticular nucleolus, interchromatinic granules, and a fibrogranular scaffold extending from the nucleolus to the nuclear lamina. The major peptides detected by 1-D SDS-PAGE were 123, 56, 46 and 41 kDa; with both methods protein profiles were similar. Identification of proteins by immunodetection reveals lamins A and C, 80 and 65 kDa respectively; no labeling was found for actin (45 kDa) and vimentin (57 kDa). In short, adrenal nuclear matrix was isolated, Kaufmann et al's method being the method of choice.

Adrenal Cortex↗