Biomedical subjects

D Afonso

Publications and source records attributed to D Afonso.

12 recordsLinked to original sources

PubMed1994

Maternal ingestion of tyrosine during rat pregnancy modifies the offspring behavioral lateralization.

It was previously reported that oral administration of tyrosine (500 mg/kg) to pregnant rats increases tyrosine and monoamines level in the fetal brain and modifies locomotion during postnatal life. In the present study, it was found that this treatment alters behavioral lateralization in the offspring. Neonatal rats whose mothers received tyrosine during the second half of gestation showed a low level of absolute and population laterality in both tail and head movements. The alteration of behavioral lateralization was also found during postnatal development and during adulthood. The T-maze behavioral ontogeny was different for tyrosine-mother and sham-treated or untreated mother rats. During adulthood, the T-max lateralization after stress sessions (a procedure that decreases alternation behavior and facilitates the quantification of behavioral lateralization) was also different in control and tyrosine-mother groups. Neonatal and adult rats showed an increase in right-side movements probability. These data provide evidence that maternal ingestion of a catecholamine precursor during gestation may induce a long-lasting modification of the behavioral lateralization of the offspring.

Administration, Oral↗

PubMed1993

Ontogeny of T-maze behavioral lateralization in rats.

Behavioral lateralization has been reported in both humans and animals. In humans, lateralization can be detected in neonates and increases to adult levels during postnatal development. Recently we reported lateralization of head and tail movements in neonatal rats. However, the postnatal ontogeny of lateralization in animals has not been previously studied. This work presents a study of rat behavioral lateralization in the T-maze test during postnatal development (from day 30 to day 60). A decrease was found in absolute (percent preferred-side choices) and population (right-left arm choices) laterality between day 30 and day 45 of postnatal life. The lateralization degree remained unchanged between days 45 and 60. Because behavioral alternation increases from day 30 to day 45, the present data suggest that animal lateralization of behavior is a phenomenon that remains throughout the subject's life span, but whose behavioral quantification could be concealed by the ontogenic increases of other phenomena such us behavioral alternation. This hypothesis could explain the high level of lateralization in neonatal rats, the low level of rat lateralization during adulthood, and the increases in lateralization induced by stress.

Aging↗

PubMed1993

Neonatal lateralization of behavior and brain dopaminergic asymmetry.

Behavioral lateralization has previously been reported in adult animals. This work presents a study of behavioral laterality and spontaneous alternation behavior in 156 neonatal rats (39 litters with two males and two females per litter). The initial tail and head lateral movements (axis body-tail or head higher than 30 degrees) were recorded after neonatal rats were gently placed along a straight line drawn on a glass surface. This test was repeated 10 times. A leftward population lateralization was found for tail movement while head movement was rightward. The alternation behavior was lower (10-25%) than that previously reported for adult rats (80-90%) and than that expected if movement was made at random (50%). Males were more lateralized than females for head and tail movements. No sex differences were observed for behavioral alternation. In 2-day-old rats (10 litters with one male and one female per litter), the right brain side had a higher content in dopamine (mesencephalon) and DOPAC (proencephalon) than the left brain side. Thus, we concluded that behavioral and biochemical asymmetries in animals are conditioned by phenomena present during prenatal or early neonatal (first hours after birth) life and that spontaneous alternation behavior is not present during the earlier stages of postnatal development.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1992

Dopaminergic neuron development in rats: biochemical study from prenatal life to adulthood.

Dopaminergic cell development has been studied mainly using morphological techniques and especially histofluorescence. However, the biochemical characteristics of dopamine (DA) neuron development and its physiological role during ontogeny are much less known. In the present article, the biochemical development of DA neurons, from day 13 of prenatal life to adulthood, is evaluated in Sprague-Dawley rats. DA was first detected on day 14 of gestation. The brain increase in this neurotransmitter begins on day 17 in the proencephalon and on day 18 in the mesencephalon, reaching on day 20 a level similar to that found during adulthood in the latter but not in the former. DA levels in the proencephalon rise slowly to adulthood level when compared to DA in the mesencephalon. The modifications observed in tyrosine levels are also largely similar to those reported for DA. Finally, the study of the first 48 h of life shows an increase in tyrosine levels and a decrease in dihydroxyphenylacetic acid levels (with a reduction of DA turnover) during the first 4-5 h of postnatal life. Since the serotonergic modification was completely different from DA modification, we conclude that the biochemical alteration of DA neurons during early postnatal development is specific. The present data suggest that DA neurons play different roles before and after reaching adult development.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1992

Laterality, alternation, and perseveration relationships on the T-maze test.

The T-maze test has been used to study several entirely different issues: spontaneous alternation behavior (SAB), perseveration behavior (PB), and behavioral lateralization. Despite the fact that in this test the behavior studied is always the same one (i.e., side choice), the possible relationships among SAB, PB, and lateralization have not been previously evaluated. The present study investigated the relationships among these functions. The results demonstrated that (a) shock increases PB and lateralization but decreases SAB, (b) practice increases lateralization and decreases SAB but does not modify PB, and (c) there are sex differences for alternation and SAB. Because these functions are expressed by the same behavioral pattern, they must be quantified simultaneously to avoid mistaken conclusions when the T-maze test is used.

Animals↗

PubMed1991

Fetal brain serotonin synthesis and catabolism is under control by mother intake of tryptophan.

Previous morphological studies reported that serotonergic neurons appear in rats in the second half of prenatal life. Initially the biochemical differentiation of these neurons before birth was studied. Both serotonin (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) was detected in the fetal brain on day 15 of gestation. During prenatal development an increase was detected in the brain levels of 5-HT (200% higher on day 19 than on day 15) and 5-HIAA (700% higher on day 19 than on day 15). Oral administration of tryptophan to pregnant rats induced a dose-related increase of tryptophan concentration in different fetal tissues, including brain. The increase in tryptophan tissue concentration was detected for low doses (50 mg/kg) and remained unsaturated after administration of high doses (1000 mg/kg). This observation suggests that the placental barrier is not effective to block the influx of high levels of tryptophan to the fetus. Tryptophan concentration in the brain is 300% higher than in the carcass and 600% higher than in the placenta. These data suggest a mechanism to assume a role in concentrating of tryptophan in the brain. Finally, it was found that an increase in brain tryptophan induced changes in both serotonin and 5-HIAA brain levels, but did not modify tyrosine, dopamine or norepinephrine levels. Thus, under physiological conditions, tryptophan hydroxylase activity in prenatal brain is probably not saturated by its substrate tryptophan.

Animals↗

PubMed1991

Sex differences in behavioral despair: relationships between behavioral despair and open field activity.

Many studies have reported sex differences in the rates of depression in humans. Due to experimental problems, the nature of these sexual differences is still unknown. In the present study, we quantify the sex differences in depression using two animal models. Both the Porsolt et al. test and the Hilakivi and Hilakivi forced swimming test have shown that the duration of immobility is higher in the male than in the female. Sexual differences in the animal models of depression are probably unrelated to general activity differences because there is no significant correlation between activity in both tests. However, the correlation between the two models of depression used reached statistical significance. Finally, the immobility levels in the Porsolt test were similar in the different stages of the estrous cycle.

Animals↗

PubMed1991

Effects of maternal stress during pregnancy on forced swimming test behavior of the offspring.

It has been reported that gonadal steroids modulate brain and behavioral sex differentiation during development. Prenatal maternal restraint also alters development by affecting gonadal steroid levels in the fetus. Prenatal maternal restraint of animals decreases sex differences for sexual behavior, locomotion, aggression, etc. In recent work on animal models, we reported that, like humans, laboratory rats show sex differences in depression. From the present study, performed on Sprague-Dawley rats, we conclude that: 1) there are sex differences for depression in two different animal models (swimming-induced immobility and natatory tests); 2) there are also sex differences in open-field behavior; 3) prenatal maternal restraint decreases sex differences for depression but does not affect sex differences in open-field behavior; 4) prenatal maternal restraint affects female but not male behavior in the two depression tests used. These results suggest that: 1) sex differences reported in animal models of depression are under the control of gonadal steroids during prenatal brain development; 2) stress during early phases of development increases the risk for depression in adulthood.

Animals↗

PubMed1990

Determination of monoamines and indoles in amniotic fluid by high-performance liquid chromatography-electrochemical detection.

A technique is presented for the separation and detection in amniotic fluid of various substances associated with catecholamine metabolism. Monoamines and their metabolites were separated using reversed-phase ion-pair high-performance liquid chromatography. Detection and quantification were performed electrochemically. The retention times of 28 standards associated with the monoamines and their precursors and metabolites were evaluated with 14 different eluents. On the basis of the retention times of each standard and the modification of the retention times of the various peaks detected in amniotic fluid, the following substances were identified in this biological fluid: 4-hydroxy-3-methoxyphenylacetic acid, 5-hydroxyindoleacetic acid, 3,4-dihydroxyphenylacetic acid, 4-hydroxy-3-methoxyphenylglycol, epinephrine, 4-hydroxy-3-methoxymandelic acid, octopamine, tyrosine and tryptophan.

3,4-Dihydroxyphenylacetic Acid↗

PubMedDate not supplied

[Surgical management of atrio-ventricular septal defects: a single-institutional experience].

OBJECTIVES: Atrio-ventricular septal (AVSD) defects include a variable spectrum of congenital malformations with different forms of clinical presentation. We report the surgical results, from a single institution, with this type of congenital cardiac malformation. Patients with hypoplasia of one of the ventricles were excluded from this analysis. POPULATION: Between November of 1998 and June of 2005, 49 patients with AVSD were operated on by the same team and in the same department. The average age was 37.3 months (medium 6 months) and 31 patients were female. In 38 patients (78%) an inter-ventricular communication was present (AVSD-complete) and of these, 26 were of the type A of Rastelli, being 13 of type B or C. The age for defect correction of the complete form was of 5.5 months, palliative surgery was not carried out on any of the patients. Associated lesions included: Down's syndrome in 22 patients (45%), patent arterial duct in 17 patients (35%), severe AV regurgitation in 4 patients (8%), tetralogy of Fallot in two (4%) and sub-aortic stenosis in one patient (2%). Pre-operatively 10 patients presented severe congestive heart failure and two were mechanically ventilated. RESULTS: Complete biventricular correction was carried out in all patients. The average time on bypass (ECC) was 74.1+/-17.5 min. and time of aortic clamping was 52.0+/-12.9 min. The complete defects were corrected by the double patch technique, and in all patients the mitral cleft was closed, except in two with single papillary muscle. There was no intra-operative mortality, but hospital mortality was 8%(4 patients), due to pulmonary hypertension crises, in the first 15 post-operative days. The mean ventilation time was of 36.5+/-93 hours (medium 7 h) and the average ICU stay was of 4.3+/-4.8 days (medium 3 days). The minimum follow-up period is 1 month and the maximum is 84 months (medium 29.5 months), during which time 4 re-operations (8%) took place: two for residual VSD's and two for mitral regurgitation. There was no mortality at re-do surgery. At follow up there was residual mitral regurgitation, mild in 17 patients and moderate in two. Four other patients presented with minor residual defects. CONCLUSIONS: The complete correction of AVSD can be carried out with acceptable results, in a varied spectrum of anatomic forms and of clinical severity. Despite the age of correction, for the complete forms, predominantly below 12 months, pulmonary hypertension was the constant cause for post operative mortality. Earlier timing of surgery and stricter peri-operative control might still improve results.

Child, Preschool↗

PubMedDate not supplied

[Ross procedure: mid term results].

UNLABELLED: The Ross procedure has been used in children and young adults for aortic valve replacement and the correction of complex obstruction syndromes of the left ventricular outflow tract. We report the mid-term results of the Ross procedure in a single institution and performed by the same surgical team. POPULATION: Between March 1999 and December 2005, 18 patients were operated on using the Ross procedure. The mean age at the time of surgery was 12 years, being 12 patients male (67%). The primary indication for surgery was isolated aortic valve disease, being the predominant abnormality in 58% of cases aortic regurgitation and in 42% left ventricular outflow tract obstruction. Associated lesions included sub-aortic membrane in 3 patients (16%), small VSD in 2 patients (11%), bicuspid aortic valve in 4 patients (22%) and severe left ventricular dysfunction and mitral valve regurgitation in 1 patient (6%). Ten of the 18 patients (56%) had been submitted to previous surgical procedures or percutaneous interventions. RESULTS: Early post-operative mortality was not seen, but two patients (11%), had late deaths, one due to endocarditis, a year after the Ross procedure, and the other due to dilated cardiomiopathy and mitral regurgitation. The shortest time of follow-up is 6 months and the longest 72 months (median 38 months). Of the 16 survivors, 14 patients are in class I of the NYHA and 2 in class II, without significant residual lesions or need for re-intervention. The 12 patients with more than a year of follow up revealed normal coronary perfusion in all patients and no segmental wall motion abnormalities. Nevertheless, two of the 12 patients developed residual dynamic obstruction of LVOT and in three patients aortic regurgitation of a mild to moderate degree was evident. Significant gradients were not verified in the RVOT. CONCLUSIONS: The Ross procedure, despite its complexity, can be undertaken with excellent immediate results. Aspects such as the dilation of the neo aortic root and homograft evolution can not be considered in a study of this nature, seeing that the mean follow up time does not exceed 5 years.

Adolescent↗

PubMedDate not supplied

[Ventricular assist in children].

We describe the use of the Berlin Heart biventricular mechanical assistance device, as a bridge to transplant in a two-years old child suffering from end stage dilated cardiomiopathy. Ventricular support lasted for 3,5 months and led to successful transplantation. We describe the clinical case, the protocols used as well as present indications, techniques and problems related to the use of mechanical heart support in children.

Cardiomyopathy, Dilated↗