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Biomedical subjects

F Sánchez

Publications and source records attributed to F Sánchez.

At least 19 recordsLinked to original sources
PubMed1992

Partial coexistence of NADPH-diaphorase and somatostatin in the rat hypothalamic paraventricular nucleus.

Coexistence of NADPH-diaphorase (ND) activity and somatostatin (SRIF) immunoreactivity was studied in the paraventricular nucleus (PVN) of the rat hypothalamus by successive incubations of the same sections. ND was found in all PVN subdivisions, mainly in the magnocellular ones. SRIF was practically restricted to the parvicellular periventricular subdivision. Contrary to other brain regions where a wide SRIF-ND coexistence has been observed, the periventricular parvicellular subdivision was the only place of the PVN where some neurons colocalize both markers. The combination of the immunocytochemical and the histochemical labelings allows a further permanent and easy-to-perform parcellation of periventricular PVN neurons.

Animals↗
PubMed1992

New cardiotonic agents related to amrinone: synthesis of 1,2-dihydro-5-arylpyridin-2-ones.

For development of new cardiotonic agents a series of 5-aryl-3,4-dihydropyridin-2(1H)-ones, related to amrinone have been prepared from methylquinolines, 2-arylacetic acid or 3-arylethanones by direct aminomethylenation and subsequent condensation-cyclization with malonamide and cyanacetamide in classic basic media or phase-transfer catalysis, in good to excellent yields. Preliminary pharmacological assays have shown that these compounds, especially 5h and 5i, have a remarkable cardiotonic effect and present a selective inhibition of PDE-III/PDE-I isolated from cat heart.

Amrinone↗
PubMed1992

Morphometrical variations of prolactin cells in response to prolonged and systemic administration of Met-enkephalin in female rats.

A stimulatory effect on prolactin secretion had been describe after acute and systemic administration of met-enkephalin, but the effects of this opioid after chronic administration has not been reported, and the response of mammotroph cells is not clear. As a complement to previous studies, a morphometric analysis (light and electron microscopy) was carried out on prolactin cells from female rats treated chronically with met-enkephalin. Clear features of cellular hyperactivity appeared after chronic and systemic administration of the opioid, and these persisted for two weeks. The changes consisted in increases of cellular, cytoplasmic and nuclear areas, volume and surface densities of the Golgi complex and rough endoplasmic reticulum, as well as the numbers of exocytotic figures. These morphological alterations were paralleled by an increase in serum prolactin levels as detected by RIA. It is concluded that the increase in the synthesis and secretory activity of prolactin cells following chronic and systemic administration of met-enkephalin is very similar to those observed after acute and intraventricular administration.

Analysis of Variance↗
PubMed1992

Immunocytochemical evidence of hypothalamic regulation of adenohypophyseal VIP in the male rat.

In order to check whether hypothalamic stimulatory or inhibitory factors exert any kind of modulation on the morphology of VIP-immunoreactive cells in the rat hypophysis, the transport of these towards the hypophyseal portal system was blocked by intraventricular administration of colchicine in adult male rats, thereafter performing a morphometric study after characterizing the VIP-immunoreactive adenohypophyseal cells by immunocytochemical techniques. Colchicine administration led to a significant increase (p < 0.01) in the number of reactive cells observed. These cells were characterized by a larger cellular area (p < 0.01), owing to increases in nuclear area (p < 0.05) and cytoplasmic area (p < 0.05). Their morphology became more regular, with a predominance of polygonal and oval cells. The results suggest that the VIP-reactive cells of the rat hypophysis are subject to a hypothalamic inhibitory influence and their activity increasing when the hypothalamic effect is interrupted by intraventricular administration of colchicine.

Animals↗
PubMed1992

NADPH-diaphorase activity in the hypothalamic magnocellular neurosecretory nuclei of the rat.

A histochemical study of the distribution of NADPH diaphorase activity in the hypothalamus of normal rats was carried out. Our study demonstrates the presence of NADPH-diaphorase activity in the circularis and anterior and posterior fornicals nuclei for the first time. Additionally, we confirm the presence of NADPH-diaphorase-stained neurons in the paraventricular (both magno- and parvicellular neurons) and supraoptic nuclei, as well as a population of isolated positive neurons (not included in any hypothalamic nuclei) located among the different nuclei. Because NADPH diaphorase has recently been shown to be a nitric oxide synthase, our study reveals a wide presence of this enzymatic activity in the hypothalamus of the rat.

Animals↗
PubMed1992

Calbindin D-28K- and parvalbumin-reacting neurons in the hypothalamic magnocellular neurosecretory nuclei of the rat.

The distribution of calbindin D-28K- and parvalbumin-reacting neurons in the hypothalamic magnocellular neurosecretory nuclei of the rat was studied using the avidin-biotin-immunoperoxidase method and highly specific monoclonal antibodies. Incubation with anticalbindin D-28K-antiserum revealed immunoreactive neurons in the following nuclei: supraoptic, paraventricular (both in the magnocellular and parvicellular regions), circularis, fornicals and medial forebrain bundle. Incubation with parvalbumin antiserum displayed immunoreactive neurons only in the circularis nucleus. Additionally, it was possible to observe scattered calbindin and parvalbumin immunoreactive neurons (which do not form part of the nuclei considered) located in the hypothalamic area between the supraoptic and the paraventricular nuclei, especially for the calbindin D-28K antiserum.

Animals↗
PubMed1992

Morphometric analysis of GH-immunoreactive cells after GH release induced by treatment with estrogen in adult male rats.

In order to elucidate the response of somatotropic cells to the influence of gonadal steroids on the regulation of growth hormone secretory patterns, a morphometric analysis was carried out on the GH-immunoreactive cells of adult male rats treated chronically with intramuscular injections of estradiol valerate. The morphometric and morphological results obtained were correlated to the serum levels of GH at the moment of sacrifice. Treatment with a daily dose of 125 micrograms of estradiol vaterate over 15 d was seen to lead to an increase (p less than 0.01) in the serum GH values accompanied by a decrease in the intensity of reaction of the GH-cells and, morphometrically, a reduction in their size (p less than 0.01) due to a decrease in the cytoplasmic area (p less than 0.01), but without significant changes in the nuclear area. Our results suggest that in male rats estrogens enhance the release of the intracellular GH pool but that they do not affect hormone synthesis to a great extent.

Analysis of Variance↗
PubMed1992

CaBP D-28k and NADPH-diaphorase coexistence in the magnocellular neurosecretory nuclei.

Coexistence of the calcium binding protein calbindin D-28k and NADPH-diaphorase activity was studied in the magnocellular secretory nuclei of the rat hypothalamus using both immunocytochemical and histochemical techniques. Coexistence was found in all the nuclei considered (supraoptic, paraventricular, circularis and fornicals nuclei) with the exception of the hypothalamic area situated between the supraoptic and the paraventricular nuclei. Since both stainings are reliable markers, not based upon the physiological characteristics at a given moment, our study provides a further characterization of the neurons in the magnocellular neurosecretory nuclei.

Animals↗
PubMed1992

Morphometric changes in GH-immunoreactive adenohypophyseal cells induced by intraventricular administration of colchicine to adult rats.

In order to elucidate whether the gender differences observed in the somatotropic cells of adult rats are mediated by hypothalamic neuropeptides, a morphometric analysis was made of the GH-immunoreactive cells of adult rats treated intraventricularly with colchicine. The morphometric and morphological findings obtained were correlated to the basal serum levels of GH at the time of sacrifice. Treatment with colchicine was seen to increase serum GH levels; this increase was accompanied by an increase in the intensity of the reaction of the GH-cells and, morphometrically, an increase in their size due to an increase in the nuclear area, but with no significant changes in the cytoplasmic area. The results suggest that in the absence of somatostatin and GRF the basal release of GH is elevated in a similar fashion in both sexes, in turn suggesting that gonadal steroids might act at hypothalamic level on the release of somatostatin and, indirectly, on the intracellular pool of GH and hormonal secretion.

Animals↗
PubMed1992

[The diagnosis of peptic ulcer penetration into the liver by endoscopic biopsy. A report of 2 cases and a review of the literature].

We report two patients and review six additional published cases with liver penetrating peptic ulcer diagnosed by the finding of hepatic tissue in endoscopic biopsies. Clinical and laboratory data were non-specific. The presence of a large (2 cm) gastric or duodenal ulcer, with malignant appearance, or a protruding mass, with secondary ulceration and located in the gastroduodenal posterior wall or in the lesser curvature of the stomach, may suggest the endoscopic diagnosis of this complication. Definitive diagnosis is established by endoscopic biopsies of the ulcer base and/or of the associated mass.

Aged↗
PubMed1992

Sex-specific response of the vasopressin-reacting neurons of the paraventricular nucleus of the rat hypothalamus following chronic administration of met-enkephalin.

Using the peroxidase-antiperoxidase immunocytochemical technique, a morphometric study of the magnocellular neurons of the Paraventricular nucleus of the rat hypothalamus, reactive to specific anti-vasopressin rabbit serum, was made. Following systemic and chronic administration of met-enkephalin the number of immunoreactive neurons was higher, especially in females. Additionally, in the females, it was possible to observe an increase in the immunoreactivity and the presence of well-stained fibres. These findings suggest, especially in females, a blockage in the release of vasopressin, facilitating its immunocytochemical visualization.

Animals↗
PubMed1991

Estrogenic modulation of met-enkephalin-induced prolactin secretion in rats.

In order to elucidate the possible role of estrogens in the sex-dependent modulation of met-enkephalin-induced prolactin secretion, and the cellular response at adenohypophyseal level, analyses of serum prolactin levels together with a morphometric study of prolactin-immunoreactive cells were carried out following intraventricular administration of the opioid to estrogen-primed male rats. Administration of the opioid led to an increase in the serum levels of the hormone and, morphometrically, a significant increase in the cellular, cytoplasmic and nuclear areas was observed. When naloxone was administered previously, the above, mentioned changes did not appear, and the values found were similar to those observed in the animals treated only with estrogens. The results suggest that the metenkephalin-induced prolactin secretion is modulated by the gonadal steroid environment.

Animals↗
PubMed1991

Concomitant changes in endothelial cell junctions and extracellular matrix components in the chick embryo aorta.

According to previous studies, a process of endothelial activation seems to be occurring in the chick embryo between days 7 and 18. Also, endothelial cells respond to collagen as a substratum between 12 and 18 days, and this response diminishes until it almost disappears after birth. In the present study, aortas from chick embryos (days 7 to 21), and from chicks (14 days posthatching) were used. The results obtained by the freeze-fracturing technique, showed that between days 12 and 14 the intramembranous particles were aggregated into linear or clustered arrays in the fracture P-face of endothelial cells. This could signify that some kind of gap junction-like coupling may occur between adjacent endothelial cells. Our results also indicate that in advanced stages (21-day-old chick embryos and 14-day-old chicks) the growth of small aggregates into larger aggregates or plaques could occur. In addition to gap junctions, the presence of macular and linear tight junctions, reported as focal tight junctions (day 14 of development) macular and linear tight junctions with free-ending strands oriented parallel to one another (21 days) and smooth contoured ridges (14 days post-hatching) were observed. This sequence of changes may represent a development from linear to macular, to a more occluding arrangement, and may also reflect an endothelial cell polarization. Histochemical study of proteoglycans was done by using cuprolinic blue according to the critical electrolyte concentration method. Cuprolinic blue-positive granular, elongated and microfibrillar materials were found in the subendothelial region, forming a meshwork that occupies the extracellular space. Qualitative and quantitative changes were observed both in proteoglycans and in other extracellular matrix components throughout development, suggesting an increase in extracellular matrix complexity. These results lead us to suggest that the assembly of a more complex extracellular matrix, concomitantly with the formation of intercellular junctions during development, might influence the polarization of endothelium in the aorta of the chick embryo.

Animals↗
PubMed1991

Periaxonal ensheathment of lobster giant nerve fibres as revealed by freeze-fracture and lanthanum penetration.

Sheath structure and permeability have been studied in the nerve fibres of lobster (Panulirus argus) walking limbs, in particular the individually ensheathed larger giant fibres, 100-150 microns in diameter, of which there are five or six in a peripheral bundle. They are easily distinguished and can be separated from neighbouring fibre bundles in which smaller giant axons (65-80 microns diameter) and many axons of much smaller diameter (5-15 microns) are ensheathed together. Each of the larger giant axons is enveloped by a Schwann cell layer outside of which is a multilayered sheath consisting of one-cell thick belts of flattened cells and interleaved zones of collagen fibrils and extracellular matrix. The cells in each belt lack basal lamina and, after freeze-fracture, as well as in thin sections, exhibit intercellular gap junctions and incomplete, fascia type, tight junctions; their most striking aspect is an exceedingly large number of exo-endocytic profiles. Permeability to lanthanum chloride in the bathing medium studied before or during fixation both in intact nerves and in nerves with surgically breached (slit) epineurium showed penetration of lanthanum tracer between the cells around the giant fibres, but the electron-dense tracer was excluded from the Schwann cell layer and the periaxonal space unless the epineurium had been slit. The extent of lanthanum diffusion was evaluated by transmission electron microscopy of thin sections and confirmed by X-ray microanalysis (EDAX) of comparable selected areas in such sections. The results indicate structural similarities but distinct permeability differences between the multilayered sheath surrounding the lobster giant axons and the vertebrate nerve perineurium. Other ultrastructural details provided by the freeze-fracture replicas concern the distribution of intramembrane particles in the axolemma and the Schwann and sheath cell membranes.

Animals↗
PubMed1991

Echinococcus granulosus: antigen characterization by chemical treatment and enzymatic deglycosylation.

Parasite antigenic fractions obtained by biochemical purification of sheep hydatid fluid were subjected to enzymatic digestion. The relative mobilities of the 5 and B antigens, before and after treatment, were analyzed by polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot. Antigenic fractions transferred to nitrocellulose were also treated with sodium metaperiodate and concanavalin A. The results indicate that antigen 5 contains a substantial amount of carbohydrates covalently linked to a polypeptide backbone, which strongly bind to concanavalin A and is removed by N-glycosidase F (PNGase F). Antigen 5 possesses complex N-linked oligosaccharides (PNGase F sensitive), without terminal N-acetyl-D-glucosamine residues (N-acetyl-D-glucosaminidase nonsensitive) and has no high-mannose oligosaccharides (endo-beta-N-acetylglucosaminidase H nonsensitive). In contrast, the antigen B of low molecular weight is not susceptible to either enzymatic digestions (PNGase F, Endo H, and N-acetyl-D-glucosaminidase) or sodium metaperiodate oxidation and it does not bind to concanavalin A. Polyclonal antibodies prepared against the two antigens reacted with the deglycosylated antigen 5 in Western blot. The dominant epitopes are, therefore, polypeptides, although the presence of carbohydrate epitopes in the native glycoproteins cannot be excluded.

Acetylglucosaminidase↗
PubMed1991

In vivo and in vitro evidence of growth hormone-releasing factor-like produced locally in the adenohypophyseal cells of the rat.

In order to characterize immunocytochemically the existence of GRF in the rat adenohypophysis and the origin of this hormone, an immunocytochemical and morphometric study was made of r-GRF-immunoreactive cells from the adenohypophysis of untreated adult rats, adult rats treated intraventricularly with colchicine and in primary cultures of adult rat adenohypophyseal cells that had been incubated with serum devoid of GRF. r-GRF immunoreactive cells were observed in untreated rat pituitaries, both male and female, although the numbers of positive cells were greater in the males (p less than 0.05) and were found to increase in number following treatment with colchicine (p less than 0.01). These cells appeared dispersed throughout the anterior lobe, without forming clusters, and were often close to blood vessels. Additionally, immunoreactive cells appeared in the cultures at 7 days of incubation. The presence of GRF-immunoreactive cells in the adenohypophysis of rats previously treated with colchicine suggests the existence of a non-hypothalamic origin for r-GRF; this is confirmed by the findings obtained in the in vitro studies which would corroborate the hypothesis that the origin of the neuropeptide is in the rat adenohypophysis itself.

Animals↗
PubMed1991

Immunochemical localization of major hydatid fluid antigens in protoscoleces and cysts of Echinococcus granulosus from human origin.

Monospecific rabbit antisera obtained through experimental immunization with previously purified proteins were used in the structural localization of two hydatid fluid antigens, antigen 5 and antigen B, in cyst membranes and protoscoleces of E. granulosus from human origin. The antigen-antibody reaction was revealed by an avidin-biotin-peroxidase technique. Antigen 5 was not evident in the laminated membrane of the cyst wall, but it was associated with the germinal membrane of the cyst wall and brood capsules. The parenchyma of invaginated and evaginated protoscoleces was heavily labelled. The tegument, the calcareous corpuscles, the suckers and the hooks did not contain antigen 5. Degenerated protoscoleces were also labelled. Antigen B localization was essentially identical to antigen 5, but degenerated protoscoleces were not recognized by anti-antigen B antiserum. Technical aspects and differences with previously published work are discussed.

Animals↗