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Biomedical subjects

S Pons

Publications and source records attributed to S Pons.

At least 55 records · Page 3Linked to original sources
PubMed1991

Ontogeny of insulin-like growth factor I, its receptor, and its binding proteins in the rat hypothalamus.

A role for the insulin-like growth factors (IGFs) in brain growth and differentiation has recently been suggested. In previous studies on fetal hypothalamic cells we found a trophic influence of IGF-I on in vitro survival and differentiation of both neurons and glia. We have now investigated the expression of IGF-I, its receptor and its binding proteins in the rat hypothalamus to determine whether endogenous IGF-I might serve as a trophic factor during development of this brain area. Both IGF-I receptors and IGF-I binding proteins showed marked developmental stage-dependent variations. Thus, IGF-I receptors as measured by both binding and cross-linking techniques, were highest during fetal life and steadily decreased thereafter to reach low adult levels. Changes in receptor numbers rather than in its affinity constant accounted for the differences seen in binding activity during development. In addition, we found 3 different IGF-I binding proteins (IGFBPs) of apparent Mr of 24, 29 and 32 kDa respectively, whose levels also showed a specific developmental pattern. Highest levels of the 29 and 32 kDA IGFBPs were found in fetal and early postnatal life, whereas levels of the 24 kDa form were highest in young adults. Changes in the concentration of IGFBPs rather than in their affinities for IGF-I accounted for the different binding capacities found. Using a specific IGF-I radioimmunoassay we found that IGF-I-like immunoreactivity (IGF-I-li) levels had no direct correlation with developmental stage. IGF-I-li levels oscillated with no apparent trend throughout development of the hypothalamus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Localization of insulin-like growth factor I (IGF-I)-like immunoreactivity in the developing and adult rat brain.

The cellular distribution of insulin-like growth factor I (IGF-I) immunoreactivity was examined in the rat brain from embryonic day 15 to maturity. IGF-I immunoreactivity was found in the perikarya of neurons distributed along the entire extension of the neuronal tube in all the embryonic ages studied (E15, E17, E19 and E21). In E21 animals, the majority of immunoreactive neurons was located in the olfactory bulb, cerebral cortex, hippocampus, striatum, diencephalon, mesencephalic colliculi, trigeminal nuclei, trigeminal ganglion and in motoneurons of the brainstem. In 10- and 20-day-old rats, in addition to the above areas, IGF-I immunoreactivity was also observed in capillary walls, ependymal cells, choroid plexus, glial cells and most fiber paths. In postnatal ages, immunoreactivity in neuronal somas was mainly restricted to the cell nuclei. However, IGF-I immunoreactivity in the neuronal cytoplasm was observed in 20-day-old rats treated with colchicine while fiber paths and neuronal cell nuclei were negative in these animals. In the telencephalon of 20-day-old rats injected with colchicine, the most intense immunoreactive neurons were observed in the olfactory bulb, cerebral cortex, tenia tecta, hippocampus, islands of Calleja, septal nuclei, striatum, endopyriform nucleus and amygdala. Most diencephalic nuclei, the substantia nigra, the mesencephalic colliculi, Purkinje cells in the cerebellar cortex and several nuclei in mesencephalon, pons and medulla oblongata were also immunoreactive. In adult rats injected with colchicine, IGF-I immunoreactivity was located in the same areas as in 20-day-old rats. The number of immunoreactive cells and the intensity of the staining was reduced in adult rats as compared to that found in young postnatal animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of loperamide and bisacodyl on intestinal transit time, fecal weight and short chain fatty acid excretion in the rat.

We analyzed the effect of drugs that modify the colonic motility on rat intestinal transit time (ITT) (measured with radiopaque markers), fecal weight (FW) and fecal concentration of short chain fatty acids (FSCFA) (assayed by gas liquid chromatography), over a four-week period. Bisacodyl was used to accelerate and Loperamide to retard the intestinal transit in rats maintained on a conventional diet. The first and 3rd week were drug-free control periods. The mean values of these periods were: ITT = 28.9h +/- 1.9 FW: 9.2 +/- 1.2 g/24 h and FSCFA = 60.6 +/- 17.9 mmol/g. After loperamide administration, we observed an increase in the mean ITT as compared to the control period (40.4 +/- 8.0h) and decrease in FW (4.8 +/- 3.6 g/24h) and in FSCFA = 32.2 +/- 5.6 mmol/g). After bisacodyl administration, we found a shorter ITT in relation to controls (24.8 +/- 2.5h), and increases in FW (27.5 +/- 3.6g/24h) and in FSCFA (108.2 +/- 39.9 mmol/g). There was a negative correlation between ITT and FW (R = 0.67 p less than 0.01) and a positive correlation between total SCFA concentration and FW (R = 0.71 p less than 0.01). The concentration of acetic, propionic and butyric acids increased with progressive increments in fecal weight, whereas concentrations of isovaleric and caproic acids decreased. The results of this study show that the FW and the FSCFA may be influenced by modifications in the intestinal transit time.

Animals↗
PubMed1990

A new precise microcomputer based rotometer.

The rotometer described here consists of a data acquisition system made of several reed relays which are activated by a small moving magnet when the animal performs rotations. The apparatus has an angular discrimination which is dependent on the number of reed relays used. A simple interface is used to normalize the pulses produced when the reed relay contacts are closed. This normalized output closes key contacts in the keyboard of a microcomputer resulting in ASCII strings. A simple BASIC program is used for computation of various turn fractions. The program also calculates the total number of movements over time, allowing the assessment of activity vs. time.

Amphetamines↗
PubMed1989

A prospective study of atrial fibrillation and stroke.

In a prospective study of 72 patients with stroke and atrial fibrillation, we classified strokes as cardioembolic or noncardioembolic based on arterial assessment using Doppler sonography and angiography. We analyzed and cross-tabulated 18 clinical characteristics and found four to be significantly associated with a cardioembolic mechanism: stroke with onset during activity and peak deficit at onset (p less than 0.008), previous infarct in a different vascular territory (p less than 0.01), previous transient ischemic attack in a different vascular territory (p less than 0.01), and transient ischemic attack lasting greater than 1 hour (p less than 0.02). Starting with these four characteristics, we used a step-down procedure to select variables for a logistic regression model. Only previous infarct in a different vascular territory (odds ratio = 7.38) and transient ischemic attack lasting greater than 1 hour (odds ratio = 7.89) were selected by the model. Using M-mode and two-dimensional echocardiography, we compared left atrial size in 46 patients with that in 78 controls who had atrial fibrillation without stroke. Left atrial size in patients and controls with mitral valvulopathy was significantly larger than that in patients and controls without mitral valve disease. There was, however, no difference in left atrial size between patients with nonvalvular atrial fibrillation and cardioembolic stroke and controls or patients with nonvalvular atrial fibrillation and noncardioembolic stroke. We concluded that some clinical characteristics are closely related to cardioembolic stroke and that left atrial enlargement reflects underlying cardiopathy rather than atrial emboli-forming capability.

Aged↗
PubMed1984

[Iso-Kikuchi syndrome. Congenital onychodysplasia of the index fingers].

We report an observation that fulfills the criterion that must be present for the diagnosis of the Iso- Kikuchi syndrome. According with the literature, this case is the observation number 56 and surely the first rapport in the countries of spanish language. Our patient presents from her birth the affection of both index fingers, in one of which she has micronichia and in the other polionichia . Nobody of her family has the syndrome. The radiographic studies shows the characteristic changes in the distal phalanx. There were no other associated malformations.

Adult↗
PubMed1984

[Weiss' nasal lymphoma (histiocytic, malignant)].

We presented a patient with a deforming and necrotizing syndrome of the nasal pyramid. The histopathology demonstrated a lymphoma. The original works of Weiss are related. The diseases is characterized by: ecotaxis of the nasal pyramid, localized persistency during a long time, malaise in advanced studies and sensibility to radiations. We proposed the name linfoma histiocitico maligno nasal de Weiss and consider it as a autonomous entity.

Adult↗
PubMed1983

[Duhringoid polymorphic dermatoses].

Under the name of Duhring-like Polymorphous Dermatitis are grouped skin diseases with the following common patterns: clinical manifestations, course and treatment. Surely are from immunological etiopathogenesis. They should be studied with microscopy and immunofluorescence.

Humans↗
PubMed1979

[Bullosis diabeticorum].

Three cases of Bullosis Diabeticorum, entity described by Rocca and Pereyra, are reported by the authors. The review of the published literature after the original article shows the importance of recognizing these symptoms for the diagnosis of an occult diabetes. The most outstanding features of the studied cases were: a) the bullosis traumatica present in the 3 observations; b) the finding of an unknown diabetes in two of the three patients; c) the association with stellate pseudoscars. The histopathologic findings were similar in all three patients.

Adult↗
PubMed1977

[Nevus lipomatosus cutaneous superficialis].

Two cases of naevus lipomatosus superficialis (Hoffmann and Zurhelle) are described by the authors. The main clinical characteristics and histological peculiarities are reviewed. Both cases were disseminated and had typical localisation (pelvic area). The histological examination showed ectopic adipocytes in the dermis. The authors mare a reference to the different hypotheses on the pathogenesis of these lesions.

Adolescent↗
PubMed1977

[Pemphigus with eosinophilic spongiosis].

A bibliographic review of a new subject-pemphigus with eosinophilic spongiosis accomplished: Three clinical courses are recognized: a) pemphigus in its initial phase, b) pemphigus markedly seborrheic, which presents during its evolution, some morphologic anomalies, c) pemphigus that appear like an authentic Duhring in its initial phase and during part of its evolution. On studying the histopathology three aspects are observed; 1) pure eosinophilic spongiosis with two modalites: diffuse or vesiculate; 2) mixed eosinophilic spongiosis and, 3) alternate eosinophilic spongiosis. The review report the study of this new observation and discusses the nosological situation as well as its pausible causation.

Adult↗