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Biomedical subjects

M Souto

Publications and source records attributed to M Souto.

At least 37 records · Page 2Linked to original sources
PubMed1990

Adrenal cytochrome-c-oxidase and P-450 in male adult rats: effects of testosterone, castration and dexamethasone.

The enzymes cytochrome-c-oxidase and P-450 were measured in adrenal cortex of male adult rats, under four experimental conditions: G1, controls; G2, orchidectomized; G3, orchidectomized and treated with testosterone and G4, orchidectomized and treated with testosterone plus dexamethasone. No differences were observed in cytochrome-c-oxidase between groups G1, G2 and G4. The highest activity was found in G3, which differs significantly from the rest of the groups. No differences were observed from cytochrome P-450 between G1 and G3 groups, while G2 and G4 differ from the G1 group. These studies support new evidences for an interaction between adrenal cortex and gonads in relation to steroidogenic and respiratory activity.

Adrenal Cortex↗
PubMed1990

An ultrastructural stereologic study of mitochondria in the neonatal adrenal cortex of the rat.

The ultrastructural changes observed during the neonatal period of the rat adrenal cortex are described. The zona juxta-medullaris cells presented round mitochondria with vesicular cristae and large endoplasmic reticulum. Variations on the surface of the mitochondrial cristae were determined by morphometric methods. The cortical cells of 1 and 10-days-old rats showed a well developed endoplasmic reticulum. Morphological analysis indicate that the number of mitochondrial cristae increase the third day, followed by a decrease. At the tenth day a second increase was observed. Plasma corticosterone was also measured. The highest levels of this hormone were found in the 1, 2 and 10-days-old rats. A decrease was observed in rats of 3 to 8 days of age. This result is coincident with the adrenal changes observed in the developing of mitochondria and endoplasmic reticulum in the neonatal period. The increase in the number of mitochondrial cristae in the three-days old rats can be considered a morphological expression of the neonatal gland in the period influenced by maternal dependence. The most important morphological and metabolic changes observed the second week of life are probably due to the maturation of the hypothalamic pituitary axis that stimulates the neonatal adrenal cortex secretion, which is independent of maternal dependence.

Adrenal Cortex↗
PubMed1989

Adrenal cytochrome-c-oxidase in neonatal and adult rats: sex differences.

Cytochrome-c-oxidase was measured in the adrenals of neonatal rats from 1 to 10 days of age and adult rats. No differences between the adrenals of female and male neonatal rats of the same age were found. Adult rats, on the contrary, showed sexual differences. Enzymatic activity was higher in males than in females. In the latter, there were important changes during the estrus cycle. The highest values were observed during diestrus and the lowest during estrus. These results provide new evidence of the close interrelations between gonads and adrenal glands during sexual maturation.

Adrenal Glands↗
PubMed1988

Catecholaminergic responses of neonatal adrenal gland to insulin.

In the present work we study a sequential degree of response to insulin (0.001 IU/g body weight) in neonatal rats, using as parameters the blood glucose and the adrenal catecholamine levels. In 1-day and 90-day-old rats treated by insulin the glycemia showed a more marked fall than the rest of neonates. After insulin administration noradrenaline content did not show differences between control and treated rats. In contrast, adrenaline depletion was significant in adults (62.20%) and in neonates of 7 and 10 days of age (45% and 35.5% respectively). No significant decrease of the amine was observed in the younger rats (1 to 4-days-old). This response to insulin probably depends on the gradual maturation and innervation of the adrenal chromaffin tissue.

Adrenal Glands↗
PubMed1985

Effect of insulin on neonatal and adult adrenal medulla in the rat.

The effect of equivalent doses of insulin on the adrenal of both adult and neonatal rats was compared. Glycemia in treated adults dropped to one third of the control, in contrast to the neonatal rat values, which decreased to about one half. After insulin, a large percentage of adult chromaffin cells showed cytoplasmic degranulation and vacuolization. In contrast, a smaller percentage of cytoplasmic changes was seen in the adrenal cells of 4- and 7-day-old rats. In rats of 10 days of age, the percentage of modified cells was similar to the adults. The morphological changes in neonatal medullae were characterized by widening of the perigranular space and enlargement of the endoplasmic reticulum cisternae. No cytoplasmic vacuolization was seen. This response of neonatal rats to insulin may indicate immaturity of the adrenal chromaffin tissue and/or of the centers involved in the mechanism of hypoglycemia-catecholamine release.

Adrenal Medulla↗
PubMed1985

The circadian optimal time for hepatectomy in the study of liver regeneration.

Standardized (light from 0600 to 1800) C3HS mice, hepatectomized at different circadian stages, were killed at 1400 (the peak time of mitotic activity in intact mice). The higher values of mitotic index were those of mice operated at 1400, 48 hr before. The curve of mitotic activity of the regenerating liver of mice operated at 1400 and that of mice operated at 0200 (an opposite time in the circadian stage) are, both, grossly in phase with the curves of mitotic index in young and adult mice liver. The amplitude of the first peak of mitotic activity in mice operated at 0200 was dramatically lower than that of animals operated at 1400. The same applies to hepatocytes as well as to the sinusoid litoral population of cells. It is concluded that 1400 hr, as contrast to 0200 hr, is an optimal time for hepatectomy if one wants to obtain the highest mitotic index first peak during regeneration in a normal phase position (the position of the mitotic index peak in the liver of normal young and adult mice).

Animals↗
PubMed1983

Prolactin secretion in normal male mice during a circadian period. An ultrastructural and biochemical study.

A quantitative ultrastructural study on the prolactin (PRL) cells of normal male mice was correlated with serum PRL immunoassay determination at different times in a circadian period. Significant time fluctuations in the percentages of cytoplasmic volume occupied by most of the organelles, as well as cyclic variations in serum PRL concentrations were detected. The endoplasmic reticulum appeared more developed at the beginning of the light period, suggesting a higher synthesis of PRL at this time. The evaluation of the Golgi complex and the secretory granules would indicate that packaging of secretory material and storing of PRL granules occurred mainly during the second half of the light period. This coincided with the lowest values in serum PRL concentration and an increment in mitochondrial mass. The highest emiocytotic activity together with a diminution of total secretory granules were found during the dark period. The peak of PRL serum concentration was also present in this phase, but some hours later. Evaluation of microtubules and lysosomes gave some additional information. The results are in keeping with those from some biochemical investigations performed in mice and rats, but are not in agreement with others. The importance of a morphometric approach to evaluate and corroborate the immunoassay methods in the study of cyclic hormone secretion is emphasized.

Animals↗
PubMed1981

Quantitative ultrastructural study of prolactin cells from lactating mice during a 24-hour period.

A quantitative ultrastructural morphometric study was performed on the prolactin (PRL) cells of lactating mice, at different times in a circadian period. The results showed significant time fluctuations in the percentages of cytoplasmic volume occupied by several organelles. The endoplasmic reticulum appeared more developed during the dark period, indicating a higher synthesis of secretory material in this phase. The Golgi complex, including an increased number of immature granules, was found remarkably enlarged during the light period. Moreover, the release of PRL would be increased during the dark phase, as judged by the diminution of the secretory granules and the higher degree of emiocytotic activity. The present morphometric approach in the detection of circadian variations of PRL secretion in lactating mice is emphasized.

Animals↗
PubMed1980

Mechanism of the ultrastructural changes induced by partial hepatectomy in the STH cells of mice.

The ultrastructural changes induced by partial hepatectomy in the STH cells of mice were examined. These changes suggest an increased secretory activity of STH cells. Therefore, several experimental procedures elucidating the possible mechanism of this effect were undertaken. Normal mice were starved for 52 h or treated with insulin, glucagon, or cAMP. Serum glucose level measurements as well as electron microscopy of pituitary STH cells were carried out in each group of animals. It was found that STH cells of glucagon- and cAMP-treated mice showed some of the ultrastructural features observed in partially hepatectomized animals. Hence, serum hyperglucagonemia and increase in pituitary cAMP content, may be important components of the complex mechanism responsible for the ultrastructural changes in STH cells brought about by partial hepatectomy.

Animals↗
PubMed1979

Antagonism by d,1-propranolol of imipramine effects in mice.

Three agents with known or suspected antidepressant activity, imipramine, salbutamol and dexamphetamine, were active in animal tests predictive of an antidepressant effect in man: antagonism of the hypothermia induced by reserpine, by oxotremorine or by a high dose of apomorphine, and the potentiation of the yohimbine-induced toxicity. These effects were antagonized by d,1-propranolol, suggesting that the stimulation of beta-adrenergic receptors could be a common mechanism underlying their effects. These results agree with the noradrenergic hypothesis of the pathophysiology of affective disorders.

Albuterol↗
PubMed1979

Ultrastructural study of somatotroph cells from mice bearing a fast growing transplanted hepatoma, in different periods of the tumor development.

The presence of a transplanted, fast-growing hepatoma (SS1-K) produces conspicuous ultrastructural changes in pituitary STH cells of C3H-S male mice. These changes are suggestive of an increased secretion of growth hormone only during the first stages of the tumor development. The hepatoma influence does not seem to be clearly related to the illumination regimen or time of killing.

Animals↗
PubMed1979

The actions of dopaminergic and noradrenergic antagonists on conditioned avoidance responses in intact and 6-hydroxydopamine-treated rats.

The actions of various doses of haloperidol, pimozide, clozapine, and phenoxybenzamine were assessed on a conditioned-avoidance response (CAR) in control and 6-hydroxydopamine-treated rats, using a pole-climbing device. Haloperidol proved to be the most potent in disrupting the CAR. Pimozide was about 1.6 times less potent, and clozapine and phenoxybenzamine were approximately 52 and 155 times less potent than haloperidol, respectively. Prior treatment with 6-hydroxydopamine slightly enhanced the sensitivity to some of the doses of the DA and NE antagonists. Significantly lower levels of responding, however, were observed only after the highest dose of primozide. Clonidine was not only ineffective in reverting avoidance decrements, but also induced a further decline of the CAR. Apomorphine produced a partial, but significant, reversal of the haloperidol and pimozide-induced depression of conditioned responses. Regarding the clozapine-pretreated animals, a significant antagonism was observed only with the smaller dose of apomorphine. The highest dose induced a further decline of the CAR. The DA agonist was also ineffective in the phenoxybenzamine-injected rats. Amphetamine was effective in antagonizing the avoidance decrements produced by all the CA antagonists. Our results support the suggestion that CAR depends on both DA and NE mechanisms. DA seems to be more significant that NE, however, since the CAR was more depressed when receptors depending on the former neurotransmitter were blocked.

Amphetamine↗
PubMed1979

Effects of clozapine on the activity of central dopaminergic and noradrenergic neurons.

The effects of clozapine on the spontaneous firing rate of noradrenergic (NE, locus coeruleus), dopaminergic (DA, zona compacta, ventral tegmental area) and non-dopaminergic (zona reticulata) neurons was studied in chloral hydrate anesthetized rats. Clozapine administered intraperitoneally significantly increased the spontaneous activity of NE and DA neurons. After a cumulative dose of 8 mg/kg clozapine, the increase of mean firing rate per min of zona compacta and ventral tegmental area neurons attained almost similar values. Amphetamine reversed the clozapine-induced stimulation of NE and DA neurons. Zona reticulata neurons were depressed by clozapine. Neither amphetamine nor physostigmine were effective in antagonizing the inhibition. Our results suggest that clozapine blocks central NE and DA receptors. Furthermore, they fail to reveal a smaller sensitivity of the striatum as compared to the limbic system to the effects of clozapine.

Amphetamine↗
PubMedDate not supplied

Evaluation of an automated wavelet-based system dedicated to the detection of clustered microcalcifications in digital mammograms.

Mammographic screening programs are delivering reductions in breast cancer mortality. However, breast cancer screening will be cost effective and will provide a real profit only when both high sensitivity and specificity levels are reached. To date, due to human or technical factors, a significant number of breast cancers are still missed or misinterpreted on the mammograms. Computer methodologies, developed to assist radiologists, could represent further amelioration by increasing diagnostic accuracy in the screening programs. We have tested a computerized scheme to detect clustered microcalcifications in digital mammograms, employing 360 mammograms that were randomly selected from the mammographic screening program, currently undergoing at the Galicia Community (Spain). After the digitization process, the breast border was initially determined. A wavelet-based algorithm was employed to detect the clusters of microcalcifications. The performance of the automated system over the test set was evaluated employing Free-response Receiver Operating Characteristic (FROC) methodology. The sensitivity achieved was 74% at a false positive detection rate of 1.83. The corresponding area under the Alternative FROC (AFROC) curve was A1=0.667 +/-0.09.

Algorithms↗
PubMedDate not supplied

A limited PACS dedicated to a research environment. Nine years' experience in Santiago de Compostela.

A digital image network has been installed at the Department of Radiology of the University of Santiago de Compostela, Spain, to create a "limited' Picture Archiving and Communication System (PACS). This experience is being dedicated to address problems associated with digital techniques in a research environment. The backbone of the system is a multiprotocol ethernet network. Attached to the network are a number of advanced devices such as DEC VAX and UNIX workstations. Currently, a high resolution film digitizer and a laser printer are under evaluation for radiologic image research. During a period of nine years, 1987 to 1995, experimental and clinical trials have been conducted on different film based digital radiography apparatus primarily dedicated to chest and breast imaging. Several research projects have been completed. In this paper we describe the results of these investigations and discuss the advantages and disadvantages of this digital technique. The results of the different completed studies will be presented separately. A description of the physical characteristics of the limited PACS system dedicated to a research environment will serve as background.

Computer Communication Networks↗