Search PubMed⌕ Search

Biomedical subjects

R Castro

Publications and source records attributed to R Castro.

At least 109 records · Page 6Linked to original sources
PubMed1989

[Electroencephalographic maturation in preterm newborn infants].

We have studied 51 preterm infants [gestational age (GE) less than 32 weeks] by: a neurologic examination at 40 weeks of postconceptional age, serial cranial ultrasonographies, weekly electroencephalograms (EEG) until 42 weeks of postconceptional age, and Brunet-Lezine test of psychomotor developmental at 1 year old. Our objective is the longitudinal study of EEG maturation in preterm infants with or without neurologic injury. In preterm infants with the less gestational age are present the EEG characteristics reported for the older infants, the typical EEG pattern is the "sawtooth" (27-30 weeks GE). If these infants are "normal", the EEG maturation get adjusted to the previous reported pattern, except for the earlier presentation of transitory acute frontal waves and the disappearance of the preterm's discontinuous trace. The EEG maturation of preterm infants with perinatal neurologic injury are significantly delayed in contrast with "normal" preterm infants until 40 weeks of postconceptional age; this fact have a poor prognosis for these infants.

Brain↗
PubMed1989

[Propranolol in the prevention of digestive bleeding in cirrhotic patients].

Propranolol was administered to fifteen cirrhotic patients at requires doses, to reduce cardiac output by 25%. Patients were followed up for a period of 1 to 2 years. Bleeding rates and esophagic varices size were compared against fifteen patients treated with placebo, serwing as control group. On the treated group only one patient showed bleeding, detected by hemoccult while controls showed a 46.6% of bleedings which cause two deaths. The endoscopic size of varices decreased in 73.3% on the treated group, this was not observed on the controls. Propranolol is a useful medicament for the reduction of esophagic varices size and prevention of digestive bleeding in cirrhotic patients.

Blood Pressure↗
PubMed1989

Vasopressin levels and pediatric head trauma.

The syndrome of inappropriate secretion of antidiuretic hormone is associated with head trauma; however, there are no reports concerning vasopressin levels in pediatric patients with head trauma. Urine vasopressin in eight children (mean +/- SEM, age 7.5 +/- 1.6 years, range 1 to 15 years) was measured by radioimmunoassay during their hospitalization for head trauma. Urine vasopressin values for ten healthy children (mean age 5.4 +/- 1.3 years) and for eight children hospitalized for systemic antibiotic treatment of infections (age 5.9 +/- 1.8 years) also were obtained. Urine vasopressin, urine and serum sodium concentration and osmolality, urea nitrogen, creatinine, and fluid intake were measured within 24 hours of admission and daily for the following two days. For the first three days following head trauma, mean urine vasopressin levels in pediatric patients with head trauma were increased (P less than .05) compared with those of healthy children. Despite fluid restriction to 85% of maintenance level, 25% of patients with head trauma exhibited the clinical syndrome of inappropriate secretion of antidiuretic hormone (hyponatremia, increased urinary sodium, diminished serum osmolality, and urine osmolality greater than serum osmolality). Urine osmolality greater than 800 mosm/kg was associated with markedly increased urine vasopressin levels (200 to 1,650 pg/mL); children with this finding may be at particular risk for the syndrome of inappropriate secretion of anti-diuretic hormone without restrictive water intake.

Adolescent↗
PubMed1989

Antiproliferative effects of lipoxygenase inhibitors on malignant human hematopoietic cell lines.

Eicosanoids regulate a wide spectrum of cellular processes including cell proliferation. We have shown previously that lipoxygenase metabolites of arachidonic acid modulate normal human hematopoiesis by in vitro colony assays. In this study we investigated the role of lipoxygenase metabolites in regulating the proliferation of several malignant hematopoietic cell lines, including K562 and EM-2 (chronic myelogenous leukemia blasts), HL-60 (promyelocytic leukemia cells), and U937 (malignant histiocytes). Piriprost, a specific inhibitor of 5-lipoxygenase, inhibits proliferation of these cell lines up to 95% with 50% cell inhibition at approximately 3 x 10(-5) M. Other less specific lipoxygenase inhibitors such as caffeic acid, nordihydroguaiaretic acid, and BW755C have similar activity in a [3H]-thymidine incorporation assay. In contrast, indomethacin, which is a cyclooxygenase inhibitor, has no suppressive effect in these assays. Inhibition by these drugs is completely reversible. Several nonhematopoietic malignant cell lines do not appear to be affected by these drugs. Two specific lipoxygenase metabolites, leukotriene B4 and leukotriene D4, stimulate leukemia cell line proliferation to 150% of control levels when added directly to cell cultures. These data suggest that certain lipoxygenase products, perhaps leukotrienes, are critical for the proliferation of malignant hematopoietic cells in vitro.

Arachidonate 5-Lipoxygenase↗
PubMed1988

Tyrosine availability and brain noradrenaline synthesis in the fetus: control by maternal tyrosine ingestion.

In spite of substantial evidence that tyrosine availability modulates catecholamine synthesis, under a variety of conditions, in adult brains, its possible influence during brain development has received little attention. In the present paper, the effect of tyrosine when administered to pregnant rats on tyrosine and noradrenaline brain levels in the fetus was investigated. In the first experiment noradrenaline (NA) was detected in the fetal brain by day 13 of development. NA levels increased from days 13 to 19. Administration of tyrosine to the mother raises both tyrosine and NA levels in the fetal brain. The increase in tyrosine was similar on days 13, 15, 17 and 19 of pregnancy. However, the increase of NA was more pronounced on days 17 and 19 than on days 13 or 15. Tyrosine and NA enhancement was detected 30 min after tyrosine administration, persisted for at least 2 h and disappeared completely 6 h after its administration. Both tyrosine and NA increase are tyrosine dose-related. The present studies suggest that there are no important barriers for tyrosine transport between the maternal blood and the fetal brain. Furthermore, during prenatal life the rate of NA synthesis is regulated by tyrosine brain concentration and therefore maternal intake of tyrosine is an important factor for noradrenaline synthesis regulation in the fetal brain. The possible functional significance of noradrenaline brain increase after tyrosine administration are unknown. However, the NA modification could be the cause of the persistent behavioral modification that we have found in adult rats whose mothers were treated with tyrosine during pregnancy.

Animals↗
PubMed1988

Prevention of post-transfusion non-A, non-B hepatitis by non-specific immunoglobulin in heart surgery patients.

To evaluate the effectiveness of immune serum globulin (ISG) in preventing non-A, non-B hepatitis, 291 heart surgery patients who received blood from voluntary donors were randomly assigned to receive either ISG or no additional protection. ISG was given intramuscularly before and 1 week after transfusion. 98 controls and 100 in the ISG group completed the study. Post-transfusion non-A, non-B hepatitis developed in 11 (11.2%) controls but in only 3 (3.0%) of the ISG group (p = 0.0203). 8 (72.7%) of control group with hepatitis had symptoms, and in 5 (45.4%) the disease became chronic. The disease was self-limiting in all 3 ISG patients affected, and only 1 of them had symptoms. Among those with non-A, non-B hepatitis aminotransferase levels were higher in the controls than in the ISG patients. Incubation periods longer than 8 weeks correlated with a tendency for the disease to become chronic. ISG recipients had shorter as well as more homogeneous incubation periods. ISG could be a safe, low-cost means for preventing post-transfusion non-A, non-B hepatitis which does not call for the discarding of donated blood.

Adolescent↗
PubMed1988

Conditioning of the early behavioral response to apomorphine in the rotational model of Parkinson's disease.

The rotational model of Parkinson's disease has been widely used to investigate the action of dopamine agonists. This animal model involves the production of a unilateral nigrostriatal lesion in rats. The lesion is produced with 6-hydroxydopamine which causes dopamine depletion and subsequent supersensitivity of striatal receptors. Thus, administration of drugs which are therapeutically effective in Parkinson's disease, elicits circling behavior contralateral to the lesioned side. The origin of the paradoxical response and the undrugged rotations observed after saline injections in apomorphine pretreated rats has not been explained. We report here that the undrugged response can be associated with the early rotational response elicited by the drug. Furthermore, we show the effect of inhibitory conditioning on this early response. Our results suggest that pharmacological conditioning plays a significant role in the modification of the therapeutic effectiveness of CNS-active drugs after extended treatments.

Animals↗
PubMed1988

Ovine fetal lung fluid response to intravenous saline solution infusion: fetal atrial natriuretic factor effect.

The fetal lung, a significant source of in utero fluid production, has been postulated to serve a regulatory role in maintenance of fetal body fluid homeostasis. Whereas the fetus responds to intravascular saline solution infusions with increased urine output, the fetal lung fluid response to this stimulus is unclear. Tracheal fluid output was measured in four chronically catheterized ovine fetuses (mean gestation, 129 +/- 1 days) subjected to successive 40-minute intravenous 0.9% saline solution infusions at rates of 0.5 and 1 ml/min/per kilogram of body weight. Tracheal fluid output decreased significantly (1.7 +/- 0.1 to 1.1 +/- 0.1 ml/10 min, p less than 0.01) during the infusion and returned to basal levels during the recovery period. Lung fluid osmolality and electrolyte concentration did not change. Fetal plasma atrial natriuretic factor increased significantly in response to the saline solution infusion (364 +/- 90 to 790 +/- 286 pg/ml, p less than 0.05) and returned to basal levels during the recovery period. There was a significant inverse correlation between plasma atrial natriuretic factor levels and tracheal fluid output. These results suggest that increased fetal plasma atrial natriuretic factor decreases lung fluid production. Lung fluid does not appear to compensate for fetal body water excess. Rather, lung fluid production appears to promote intrauterine pulmonary growth and to facilitate the transition to the extrauterine environment.

Animals↗
PubMed1988

Hemodynamic effects of nitrendipine on systolic ventricular function, diastolic ventricular function, and peripheral circulation in essential hypertension.

Twenty patients (aged 33-60 years) with mild to moderate essential hypertension were studied to assess systolic ventricular function, diastolic ventricular function, and peripheral hemodynamic changes induced by nitrendipine during rest and effort, comparing the acute and chronic treatment phases. We used a randomized, placebo-controlled, double-blind, crossover protocol in the acute phase and a paired, placebo group controlled study, with 20 mg single oral daily dose for a 3-week treatment period (chronic phase). The cardiac and peripheral hemodynamic parameters were quantified by noninvasive radionuclides techniques. During acute treatment, peripheral hemodynamics showed a predominantly arteriolar vasodilatory effect with a significant fall in the previously elevated forearm vascular resistance values (-38%, p less than 0.01) and an important increase in forearm blood flow (+49%, p less than 0.01) without any changes in venous capacity. Simultaneously, nitrendipine produced a significant drop in total peripheral resistance (-36%, p less than 0.01), systolic blood pressure (-13%, p less than 0.01), and diastolic blood pressured (-17%, p less than 0.01). The sudden reduction in left ventricular (LV) afterload caused a reflex increase in heart rate (HR) (+12%, p less than 0.01), cardiac index (+37%, p less than 0.01), LV ejection fraction (+17%, p less than 0.01), and peak ejection rate, with an important decrease in LV end systolic volume (-30%, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Maternal dehydration-rehydration: fetal plasma and urinary responses.

Pregnant women may be exposed to exercise, thermal, or gastrointestinal (hyperemesis) water loss, all of which commonly induce a greater than 10 mosmol increase in plasma osmolality. Although fetal osmolality is dependent on maternal osmolality, the impact of maternal dehydration and subsequent maternal rehydration on the fetus has not been explored. Five pregnant ewes with singleton fetuses (136 +/- 1 day) were water deprived for 36 h resulting in a significant increase in plasma osmolality (298 +/- 3.4 to 313 +/- 5.0 mosmol). In response to maternal dehydration, fetal plasma osmolality (297.0 +/- 4.1 to 309.3 +/- 4.1 mosmol), arginine vasopressin (AVP) levels (1.5 +/- 0.2 to 7.9 +/- 1.0 pg/ml), hematocrit (35.1 to 38.6%), and urine osmolality (161.3 +/- 10.7 to 348.9 +/- 21.9 mosmol) significantly increased. Subsequently, ewes were rehydrated over 4 h with intravenously infused 0.45% saline (20 ml.kg-1.h-1). In response to maternal rehydration, maternal and fetal plasma osmolality decreased to basal values (298.9 +/- 3.2 and 300.1 +/- 3.8 mosmol, respectively) and fetal glomerular filtration rate (1.72 +/- 0.30 to 3.08 +/- 0.66 ml/min) and urine volume significantly increased (0.33 +/- 0.02 to 0.71 +/- 0.13 ml/min). However, fetal hematocrit (37.4%), plasma AVP (3.1 +/- 0.9 pg/ml), and urine osmolality (255.4 +/- 28.8 mosmol) did not return to basal levels during the observation period. These results demonstrate fetal hyperosmolality, blood volume contraction, AVP secretion, and altered urine production in response to maternal dehydration. Despite maternal rehydration and normalization of maternal and fetal plasma osmolality, fetal endocrine and fluid responses are prolonged.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Ovine fetal and adult atrial natriuretic factor metabolism.

Studies were conducted to quantify ovine fetal and adult atrial natriuretic factor (ANF) metabolism. A total of 14 pregnant ewes with singleton fetuses were prepared with vascular catheters. In protocol 1, six fetuses (mean gestation, 131 +/- 1 days) received intravenous infusions of synthetic human ANF (hANF, 100 ng.min-1.kg-1) for 60 min. Mean basal fetal plasma ANF levels increased from 180 +/- 44 pg/ml to a steady-state level of 1,233 +/- 192 pg/ml. In protocol 2, five fetuses (mean gestation, 130 +/- 1 days) received successive 40-min infusions of hANF at 5, 25, and 100 ng.min-1.kg-1. Although basal fetal plasma ANF levels (522 +/- 135 pg/ml) were greater than those observed in protocol 1, fetal plasma ANF levels increased to 1,580 +/- 295 pg/ml at the highest infusion rate. In both protocols 1 and 2, basal fetal plasma ANF levels were three- to fourfold greater than maternal levels. The fetal plasma ANF clearance rates calculated from protocol 1 and from the 25- and 100-ng.min-1.kg-1 infusions from protocol 2 were similar (89 +/- 10, 120 +/- 31, and 116 +/- 38 ml.min-1.kg-1, respectively) and were combined to yield a mean estimated fetal plasma ANF clearance rate of 102 +/- 11 ml.min-1.kg-1. In protocol 3, adult plasma ANF levels increased from 137 +/- 36 to 4,142 +/- 776 pg/ml in response to ANF infusion at 200 ng.min-1.kg-1. The mean plasma ANF clearance rate calculated for the adult animals was 59 +/- 12 ml.min-1.kg-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Conditioned response to apomorphine in nigro-striatal system-lesioned rats: the origin of undrugged rotational response.

Development and time-course characteristics of Early rotational response (ER) to apomorphine in 6-hydroxydopamine-lesioned rats is explored. We show here how this ER can be considered a conditioned response that arises when the drug is repeatedly administered, according to a classical conditioning paradigm. In this way, the ER to apomorphine can be considered a non-pharmacological, conditioned, placebo response, the drug action being the unconditioned stimulus (UCS). In our model, the undrugged rotational response elicited by saline injections two weeks after drug treatment can be considered as the conditioned response (CR) to the conditioned stimulus, the CS being the environment associated with the drug treatment. This CR had not previously been identified during the drug treatment. Thus, we studied the acquisition of the ER, nonexistent after the first injection of apomorphine. Furthermore, we distinguish between this ER and the later, strictly pharmacological rotational response (LR) to apomorphine. Finally, we related this ER to the undrugged, paradoxical response to saline. In conclusion, we demonstrate the paradigm of pharmacological conditioning using this animal model of Parkinson's disease, supported by our own results and those of Silverman and Ho (1981).

Animals↗