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Biomedical subjects

J L Castillo

Publications and source records attributed to J L Castillo.

At least 37 records · Page 2Linked to original sources
PubMed1993

Suppressive effect of simultaneous injection of ACTH1-10 and beta-endorphin on brain [3H]flunitrazepam binding.

Seven-day hypophysectomized rats were intracerebroventricularly (i.c.v.) injected with beta-endorphin, ACTH1-10 or beta-endorphin+ACTH1-10 (10-20 ng of each compound) and the [3H]flunitrazepam ([3H])FNZ) binding to the rat cerebral cortex of hypophysectomized rats was assayed one hour later. The i.c.v. injection of ACTH1-10 (10-20 ng) or beta-endorphin (10-20 ng) significantly increased [3H]FNZ binding to a similar extent. The effect of i.c.v. injection of ACTH1-10 on brain binding was blunted by simultaneous beta-endorphin administration at the same doses. The i.c.v. naloxone injection (10-20 ng) did not modify the effect of ACTH1-10 (10 ng) on [3H]FNZ binding, but counteracted, in a dose-related manner, the blocking effect of beta-endorphin on ACTH1-10-dependent brain [3H]FNZ binding. The results suggest the existence of an opioid-melanopeptide integration to control brain benzodiazepine receptors.

Adrenocorticotropic Hormone↗
PubMed1993

Similarity between the effects of suprachiasmatic nuclei lesions and of pinealectomy on gonadotropin release in ovariectomized, sulpiride-treated and melatonin-replaced rats.

The aim of this study was to compare the effects of pineal indole treatments on LH and FSH release in pinealectomized and suprachiasmatic lesioned and ovariectomized rats rendered hyperprolactinemic by acute sulpiride treatment. Pinealectomy or suprachiasmatic nuclei lesions in female rats both decreased plasma LH and FHS at 10, but not at 20 d after surgery, whereas the daily afternoon administration of melatonin effectively restored levels of both gonadotropins to control values. In ovariectomized rats, pinealectomy or suprachiasmatic nuclei lesions were ineffective in counteracting the high plasma levels of LH and FSH. However, sulpiride treatment in both pinealectomized and suprachiasmatic nuclei lesioned and castrated female rats significantly decreased the levels of LH and FSH, an effect which was counteracted by daily afternoon melatonin administration. Other pineal indoles tested, i.e., 5-hydroxy- and 5-methoxytryptophol, were ineffective in regulating gonadotropin levels. The results suggest that the pineal gland, through its hormone melatonin, can modulate gonadotropin secretion by acting on a dopamine mechanism independent of hypothalamic suprachiasmatic areas.

Animals↗
PubMed1993

Intracerebroventricular injection of naloxone blocks melatonin-dependent brain [3H]flunitrazepam binding.

The pineal hormone melatonin modulates the brain benzodiazepine binding sites and its circadian rhythm. In the present study the effects of intracerebroventricular (i.c.v.) administration of naloxone (10-20 ng), alone or in association with melatonin and/or beta-endorphin, on [3H]flunitrazepam ([3H]FNZ) binding to the rat cerebral cortex of hypophysectomized rats was investigated. Melatonin (10-20 ng), beta-endorphin (10-20 ng), and melatonin + beta-endorphin (10-20 ng of each compound) all increased [3H]FNZ binding to a similar extent and in a dose-related manner. The effects of melatonin (10 ng) on [3H]FNZ binding were prevented by simultaneous injection with the specific opioid antagonist naloxone. Naloxone also blocks, although to a lesser extent, the effects of beta-endorphin and of melatonin + beta-endorphin injections. Moreover, naloxone blocks the hypophysectomy-dependent increase in [3H]FNZ binding. These results implicate the modulation of melatonin-dependent changes on brain benzodiazepine receptors by opioid peptides.

Adrenal Cortex Hormones↗
PubMed1993

Southernmost carriers of HTLV-I/II in the world.

To clarify the real distribution of HTLV-I and -II carriers among indigenous people in central and South America, blood samples collected from indigenous people in isolated regions of Southern Chile were examined. Among 199 inhabitants from Chiloe Island and Pitrufquen town, three cases (1.5%) showed positive anti-HTLV-I antibodies. Two out of the three (82-year-old male and 58-year-old female) reacted to HTLV-II-specific Gag and/or Env proteins but not to HTLV-I-specific ones. The latter case was confirmed as an HTLV-II carrier by polymerase chain reaction test.

Aged↗
PubMed1993

[Preliminary study of HTLV-I seroprevalence in Chilean Indian populations].

Aiming to seek the origin and define the prevalence of HTLV-1 infections, 464 blood samples from aboriginal populations proceeding from isolated regions of the north and south of Chile were studied. Antibodies against HTLV were measured with agglutination tests and confirmed with immuno-fluorescence and Western Blotting. Seven out of 107 (6.5%) blood samples from Atacama indians, 2 out of 202 (1%) from Mapuche indians and 3 out of 155 (1.9%) from Huilliche aborigines were positive. These results highlight an important presence of the virus in indigenous populations, specially in the extremes of the country. These findings could suggest an indigenous (mongoloid) origin of HTLV-1 in Chile, specially in Chiloe, where apparently there has been no contact with african or japanese populations, that could be the origin of the contamination.

Adolescent↗
PubMed1992

Characterization of ouabain high-affinity binding to rat cerebral cortex. Modulation by melatonin.

High-affinity [3H]ouabain binding to membrane preparations of rat cerebral cortex was examined using a rapid filtration procedure. At 37 degrees C, binding reached equilibrium in about 60 min. Scatchard analyses of the data at equilibrium revealed a single population of binding sites with a dissociation constant of KD = 3.1 +/- 0.36 nM and a binding site concentration of Bmax = 246.4 +/- 18.4 fmol/mg protein. Kinetic analyses of the association and dissociation curves indicated a kinetic KD = 4.6 nM, which is in good agreement with the value obtained at equilibrium. When various digitalis compounds were tested for their ability to inhibit [3H]ouabain binding, the following Ki values (nM) were obtained: ouabain (3.9); digoxin (18); acetyl-digitoxin (66); k-strophanthin (95); digitoxin (236). When melatonin was added to the incubation medium, the ability of ouabain to inhibit [3H]ouabain binding increased in a dose-related manner to yield the following Ki values (nM): melatonin 10 nM (2); melatonin 20 nM (1.2); melatonin 40 nM (0.8). These data suggest the existence in the rat cerebral cortex of high-affinity ouabain binding sites which may be a locus for the molecular action of melatonin.

Animals↗
PubMed1992

Multiple sclerosis in Chile.

So far as we know this series of 68 cases is one of the first clinical accounts of multiple sclerosis in South America. Average age of onset was 30.7 years and female:male ratio was 2:1. The most frequent initial symptom was motor impairment and less frequent was visual loss. Most affected site of involvement in established cases was the optic nerve. There were no familial cases. The severity of the disease in Chile proved to be the same as elsewhere. No characteristic clinical pattern peculiar to the region emerged.

Chile↗
PubMed1992

Modulation by pineal gland of ouabain high-affinity binding sites in rat cerebral cortex.

To investigate the participation of the pineal gland and its hormone melatonin on Na(+)-K(+)-ATPase (the sodium pump) in rat brain, we used Scatchard plots to analyze the changes in rat cerebral cortex of [3H]ouabain high-affinity binding in groups of intact, pinealectomized (PX), and sham-PX rats. Only one type of binding site, with a dissociation constant of approximately 3 nM and site number (Bmax) of approximately 250 fmol/mg protein, was apparent with our assay conditions. PX or sham-PX rats (subjected to surgery 15 days earlier) were killed at six different time intervals during the 24-h cycle. Intact and sham-PX animals showed a similar biphasic pattern in diurnal rhythm of ouabain binding, with a minimal concentration of binding sites at 1600 h and a maximal concentration at 0400 h. Pinealectomy induced a significant increase in Bmax at all time intervals studied, with the largest rise appearing at night and coinciding with the nocturnal peak, whereas the daytime minimum was blunted. Time-dependent experiments indicated that the Bmax of ouabain high-affinity binding in PX rats attained maximal values at 7 days after surgery and decreased somewhat 7 days later, while sham-PX animals showed only a small transient increase in Bmax up to 7 days after surgery, with values returning to normal by the 15th day. Melatonin administration at a single subcutaneous dose of 25 micrograms/kg body wt given 3 h before death was enough to counteract the PX-induced increase of ouabain high-affinity binding. Melatonin was able to enhance the binding of [3H]ouabain to its receptor site, increasing binding affinity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Progressive spastic paraparesis associated with human T-cell leukemia virus type I (HTLV-I).

Patients with progressive spastic paraparesis (PSP), commonly middle-aged women, are distributed throughout the country of Chile. During the three years from 1987 to 1990, we collected 83 cases of PSP from among 225 patients with various neurological diseases. The clinical picture was of a bilateral pyramidal syndrome, with sensory deficits in only 15.5% of the cases, and a slow illness progression in the majority of them. In patients with PSP, antibody to human T-cell leukemia virus type I (HTLV-I) was analyzed by enzyme linked immunosorbent assay (ELISA) and confirmed by western blot analysis. Forty-five (54.2%) patients were anti-HTLV-I antibody positive in cerebrospinal fluid (CSF) and peripheral blood. Among them, 2 patients had leukemia/lymphoma and one had Sjögren syndrome. In the laboratory study of seropositive PSP, mononuclear pleocytosis was found in 35.7%; there was an abnormal increase of the IgG index in 66.6% and an increase in CD2 in blood and CSF, and CD4 in blood. A delayed latency of somatosensory evoked potentials was observed in 90.9%. The neuropsychological study revealed a WAIS with a mean verbal IQ of 80.7 and a mean performance IQ of 84.8. The most impaired items were digit symbol and digit span. Seven subjects (18.9%) with anti-HTLV-I antibody were found among 37 relatives from 19 anti-HTLV-I positive cases of PSP.

Adult↗
PubMed1992

[HTLV-I clinical pathological spectrum].

HTLV-I has been revealed as the etiological factor of the Tropical Spastic Paraparesis (TSP) and of the T-cell leukemia-lymphoma of the adult (ATLL). Recently, it has also been associated to some forms of polymyositis, polyarthritis, polyneuropathies, Sjögren's syndrome, thrombocytopenia and lympho-alveolitis. The clinical and pathological spectrum of this retrovirus is analyzed taking into account the Chilean cases and those reported by the international medical literature.

Arthritis, Infectious↗
PubMed1991

Pinealectomy increases ouabain high-affinity binding sites and dissociation constant in rat cerebral cortex.

The effect of the pineal gland on the ouabain high-affinity binding sites (Kd = 3.1 +/- 0.4 nM, Bmax = 246.4 +/- 18.4 fmol/mg protein) in rat cerebral cortex was studied. Pinealectomy increased Bmax (940.7 +/- 42.8 fmol/mg protein) and Kd (7.6 +/- 1.5 nM) while melatonin injection (100 micrograms/kg b.wt.) counteracted these effects, restoring kinetic parameters (Kd = 1.9 +/- 0.05 nM; Bmax = 262.2 +/- 29.6 fmol/mg prot) to control values. Melatonin activity on ouabain binding in vitro did not depend upon a direct effect on the binding sites themselves. However, in competition experiments, melatonin increased binding affinity of ouabain as shown by the decreased IC50 values.

Animals↗
PubMed1991

Evoked potential abnormalities in progressive spastic paraparesis associated to HTLV-1.

The electrophysiological features of progressive spastic paraparesis (PSP) associated with HTLV-1 in Chile, a non-tropical country, are presented. Twenty-two of 45 PSP subjects were positive for HTLV-1 antibodies. Trimodal evoked potentials were all normal in only 2 of these cases (9.1%). Somatosensory evoked potentials (SSEPs) were abnormal in 19 patients (86.3%) with a mean amplitude of 1.31 uV SD 0.92. Visual evoked potentials (VEPs) and brainstem auditory evoked potentials (BAEPs) were normal in all patients except four. Peripheral nerve conduction was normal in all but one who showed discrete slowness of the motor conduction velocity in the peroneal nerves. EMG was normal in 15 cases in whom it was performed. SSEP's were abnormal in 2 (8.7%) of 23 HTLV-1 negative cases with a mean amplitude of 2.4 uV SD 1.5, which is statistically different with respect to the positive cases (p less than 0.001). These results support an involvement of the spinal cord not restricted to the pyramidal tracts but also including subclinical damage of the posterior columns in PSP associated to HTLV-1.

Adult↗
PubMed1991

[Clinical and legal aspects of brain death criteria: evaluation of the degree of knowledge of neurologists and neurosurgeons].

The level of knowledge of clinical and legal aspects of brain death criteria was tested in 25 neurologists and 15 neurosurgeons. The answers were wrong or the questionnaire had not been responded in 36.9% of the cases. The highest percentage of mistakes concerned the apnea test and what Chilean law said regarding brain death. No differences were found between neurologists and neurosurgeons. Physicians with less than 10 years were better informed than those with more than 10 years of medical practice (p < 0.005). Although brain death as a criterion of death is accepted by Chilean law in order to donate organs for transplantation, a considerable percentage of physicians (30%) rejected this concept. The significant lack of knowledge found in this study may suggest that brain death diagnosis is being inadequately performed in many cases. This fact raises important medical, ethical and legal considerations.

Brain Death↗
PubMed1990

Influence of the pituitary-adrenal axis on benzodiazepine receptor binding to rat cerebral cortex.

The role of the pituitary-adrenal axis on receptor binding and diurnal rhythmicity of benzodiazepines (BNZ) was assessed in the rat cerebral cortex. Groups of intact, adrenalectomized (ADx) and/or hypophysectomized (HPx) rats were killed at six different time intervals during the 24-hour cycle. BNZ binding was estimated by Scatchard analysis of 3H-flunitrazepam high-affinity binding to rat cerebral cortex. Intact and sham ADx animals show a similar pattern in diurnal thythm of BNZ binding, with a maximal concentration at midnight. Bilateral ADx induced a significant increase in Bmax at all time intervals studied, the largest rise appearing at midnight. HPx alone led to a slightly smaller rise in Bmax than in ADx rats, while HPx performed in ADx rats did not modify the response to ADx alone. Bmax of BNZ binding in ADx rats reached maximal values at 3-7 days after surgery, and decreased somewhat at 15 days post-ADx. Corticosterone administration at a single dose of 5 mg i.p. 24 h before sacrifice returned Bmax to normal values in ADx as well as in ADx plus HPx rats. The corticosterone effect is not exerted on the BNZ binding sites themselves, as revealed by the lack of effect of this glucocorticoid in vitro. These findings indicate that BNZ receptors in rat cerebral cortex can be modified by the adrenal gland, with corticosterone as a primary effector.

Adrenalectomy↗
PubMed1990

[HTLV-I retrovirus in Chile: study on 140 neurological patients].

We screened 140 patients with different neurological diseases for the presence of anti HTLV-1 virus antibodies. ELISA test confirmed with Western Blot analysis was performed in CSF and blood. Positive findings were obtained in 23 out of 52 patients with progressive spastic paraparesis (44%). All patients with multiple sclerosis, polymyositis, amyotrophic lateral sclerosis or chronic polyneuropathy were negative. Patients with progressive spastic paraparesis and positive HTLV-1 antibodies were most commonly women (78%) and middle aged (mean 46 years old), with a history of surgical interventions (70%) or blood transfusion (35%). A slowly progressive spastic paraparesis with asymmetric onset and minimal sensory complaints was observed in some cases. Mononuclear pleocytosis in the CSF was observed in 35% with an increased IgG index in 88%. A delayed latency and low amplitude of somatosensory evoked potentials was observed in 89% of patients.

Adolescent↗
PubMed1989

Lesions in suprachiasmatic nuclei simulate effects of pinealectomy on prolactin release in ovariectomized and sulpiride-treated female rats.

Previous studies indicate that the pineal gland alters prolactin secretion, and it was suggested that at least part of the effect of the pineal hormone melatonin on prolactin release may be mediated by the hypothalamic structures. In this study, pinealectomy and lesions of the suprachiasmatic nuclei were found to alter serum levels of prolactin in the same direction, an effect that was counteracted by daily afternoon melatonin administration. Melatonin, but not other pineal indoles, also prevented sulpiride-induced prolactin secretion in pinealectomized or suprachiasmatic nuclei-lesioned and ovariectomized rats, which suggested that the pineal gland can modulate prolactin secretion by acting through a dopamine mechanism independent of hypothalamic suprachiasmatic structures.

Animals↗
PubMed1989

Successful thrombolysis on a mechanical tricuspid prosthesis.

Recombinant tissue-type plasminogen activator (rt-PA) is presently used for the treatment of different clinical entities, mostly myocardial infarction. Its use for treatment of thrombotic dysfunction of prosthetic cardiac valves is more recent and has been only rarely reported. A 33-year-old woman with a St Jude Medical prosthesis in the tricuspid position, had suffered from thrombotic dysfunction of her prosthesis for more than 2 months. She was treated with rt-PA, and after infusion of 70 mg, the prosthesis functioned normally. She showed a moderate systemic fibrinolytic state associated with mild bleeding complications.

Adult↗