PubMed Health⌕ Search

Biomedical subjects

G Torres

Publications and source records attributed to G Torres.

At least 37 records · Page 2Linked to original sources
PubMed1999

Detection of fluoxetine in brain, blood, liver and hair of rats using gas chromatography-mass spectrometry.

This study reports the measurements of fluoxetine in discrete brain regions, blood, liver and hair of male rats injected with 10 mg/kg fluoxetine HCl for 15 consecutive days. Concentrations of the antidepressant were obtained by gas chromatography-mass spectrometry (GC-MS) methodology. In brain, fluoxetine levels were unevenly distributed, with the raphé nucleus containing the highest amounts relative to the hypothalamus or striatum. Fluoxetine was also measured in blood and liver roughly paralleling those ratios described in previous rodent studies. Of potential interest, fluoxetine was found to accumulate in rat hair after chronic treatment. Detection of fluoxetine in hair by GC-MS could be used as a marker for probative analyses.

Animals↗
PubMed1999

Behavior and drug measurements in Long-Evans and Sprague-Dawley rats after ethanol-cocaine exposure.

Long-Evans and Sprague-Dawley rats show differential behavioral responses to cocaethylene, a metabolite derived from the simultaneous ingestion of ethanol and cocaine. Such differences may also be manifested when these outbred strains are exposed to ethanol and cocaine. To test this hypothesis, both strains were fed an ethanol-diet (8.7% v/v) in conjunction with cocaine (15 mg/kg) injections for 15 days. The following parameters were evaluated: (a) ethanol consumption, (b) cocaine-induced behavioral activity, (c) blood ethanol levels, (d) blood, liver, or brain cocaine and cocaethylene levels, and (e) liver catalase and esterase activity. We found that Long-Evans rats drank significantly more of the ethanol diet relative to the Sprague-Dawley line during the first few days of the test session. This rat phenotype also differed significantly from the Sprague-Dawley line in terms of behavioral activity after cocaine administration. Blood ethanol levels did not differ between strains. Similarly, we failed to detect strain-dependent differences in blood, liver, or brain cocaine levels as measured by gas chromatography/mass spectrometry. Cocaethylene levels, however, were higher in blood and brain of Long-Evans relative to Sprague-Dawley cohorts. Although the ethanol-cocaine regimen produced a marked suppression of catalase and esterase activity compared with control-fed rats, this suppression was roughly equivalent in both rat phenotypes. These data are discussed in the context of genotypic background and vulnerability to polysubstance abuse.

Animals↗
PubMed1999

Splenic vein aneurysm: is it a surgical indication?

Splenic vein aneurysms are rare and are usually caused by portal hypertension. Symptoms are unusual, but may include rupture or abdominal pain. Diagnosis can usually be made either by means of duplex ultrasonography or computed tomography scanning. Treatment varies from noninvasive follow-up to aneurysm excision. We report an expanding splenic vein aneurysm in a young woman with abdominal and back pain and no history of portal hypertension. She was treated with aneurysm excision and splenectomy.

Abdominal Pain↗
PubMed1999

Determinants of left ventricular mass in untreated mildly hypertensive subjects: hospitalet study in mild hypertension.

The objectives of this cross-sectional study were to identify the determinants of left ventricular mass in untreated mildly hypertensive subjects at the Hypertension Unit, Department of Internal Medicine, Red Cross Hospital, Hospitalet de Llobregat, Barcelona, Spain. One hundred seventy-one untreated mildly hypertensive subjects, with a mean age of 41.1+/-11.8 years (from 18 to 65 years) were sequentially visited in our Unit; 54% were men. Echocardiographic measurements of good quality were obtained in 142 subjects (83%). Two-dimensional guided M-mode echocardiograms were used and left ventricular mass was estimated according to the Penn convention. Left ventricular mass (LVM) was analyzed as a continuous variable. In the bivariate analysis, the variables that significantly correlated with LVM were patient's height (r = 0.42, P<.0005), weight (r = 0.47, P< or =.0005), heart rate (r = -0.22, P = .01), HDLc (r = -0.30, P = .002), hematocrit (r = -0.28, P = .001), urinary sodium excretion (r = 0.23, P = 0.012), and different measurements from the ambulatory blood pressure profile for 24 h. By means of multiple regression analysis, a maximum of 41.2% of LVM variability could be explained from the factors registered in our study. The final model included age, gender, patient's weight, and diastolic night load from ambulatory blood pressure monitoring. When added to different models, weight and diastolic night load showed a similar strength in predicting left ventricular mass. In untreated patients with mild hypertension, traditional factors such as blood pressure levels explain a maximum of 41.2% of LVM variability. More knowledge is needed about factors that may alter cardiac morphology in the evolution of hypertensive patients.

Adolescent↗
PubMed1999

Correlation of parathyroid scanning and anatomy in 261 unselected patients with sporadic primary hyperparathyroidism.

BACKGROUND: Despite abundant literature on parathyroid scanning with technetium 99m-labeled cationic complexes, comprehensive clinical reports that unequivocally correlate scanning findings with the anatomy of parathyroid glands in extensive and homogeneous cohorts of patients are lacking. METHODS: We analyzed the records of patients with sporadic primary hyperparathyroidism who had had a preoperative scan with either 99mTc-labeled sestamibi or 99mTc-labeled tetrofosmin at our institution and who were cured after a bilateral surgical neck exploration procedure. RESULTS: In 261 patients, 710 normal and 347 abnormal glands (1494 +/- 2626 mg), including 15 glands within the mediastinum, were identified. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of scanning were 82%, 98%, 91%, 94%, and 94%, respectively, in 197 patients with uniglandular disease and 53%, 98%, 98%, 60%, and 72%, respectively, in 64 patients with multiglandular disease. False-positive uptakes were encountered in 17 patients (7%), 3 false-positive uptakes being within the mediastinum. If the unilateral approach had been followed, guidance with preoperative scanning would have significantly increased the number of effective unilateral neck exploration procedures (164 patients (63%) vs 78 patients (30%); P < .001). One abnormal gland would also have been neglected in 28 patients (11%). CONCLUSIONS: Preoperative scanning would limit neck exploration procedures in two thirds of patients with sporadic primary hyperparathyroidism but may also increase the risk of failure in the most challenging cases.

Adult↗
PubMed1998

Effects of cocaethylene on dopamine and serotonin synthesis in Long-Evans and Sprague-Dawley brains.

We examined the behavioral and neurochemical effects of cocaethylene treatment in Long-Evans (LE) and Sprague-Dawley (SD) rats. Cocaethylene-induced behaviors were significantly less in LE rats. Cocaethylene caused an inhibition of dopamine synthesis in the caudate nucleus and nucleus accumbens that was equivalent in both rat lines. Serotonin synthesis was also suppressed by cocaethylene treatment, however this phenomenon was less pronounced when compared with the effects on dopamine synthesis.

5-Hydroxytryptophan↗
PubMed1998

Activating properties of cocaine and cocaethylene in a behavioral preparation of Drosophila melanogaster.

The use of Drosophila as a model to study the behavioral consequences of stimulant drugs was analyzed in an active preparation of decapitated Drosophila. Application of cocaine and cocaethylene to discrete nerve cord cells regulating motor programs of behavior produced striking patterns of behavioral activity in a concentration-related manner. In general, intense circling behavior and significant wing buzzing activity were distinguishable behavioral markers in flies treated with mM concentrations of cocaine or cocaethylene. The significant changes in motor behavior induced by stimulant drugs in decapitated flies were not reproduced by the application of apomorphine, a direct dopamine (DA) agonist, or octopamine, a naturally occurring transmitter in arthropods. Because both cocaine and cocaethylene interfere with DA reuptake in mammals, we characterized the role of DA receptors mediating increased stereotypy and motor behavior in flies. Coadministration of SCH-23390, a specific D1 receptor antagonist, significantly attenuated the behavior-activating properties of cocaine and cocaethylene in this active experimental preparation. Therefore, the receptor protein mediating the behavioral responses to stimulant drugs in Drosophila is pharmacologically similar to the mammalian D1 subtype. In rats, cocaine- and cocaethylene-induced behavioral activity is complex, with increasing evidence that the D1 receptor interacts significantly with N-methyl-D-aspartate (NMDA) receptor pathways to produce an altered behavioral phenotype. To further characterize additional receptor subtypes targeted by the actions of cocaine and cocaethylene, we pretreated flies with MK-801 and dextromethorphan. Both of these drugs are potent, selective noncompetitive NMDA receptor antagonists. Interestingly, MK-801 and dextromethorphan profoundly reduced the behavior-activating properties of cocaine and cocaethylene in Drosophila. Therefore, as in rats, the NMDA (and D1) receptor pathways in this arthropod represent obligatory targets for the behavioral effects of stimulant drugs.

Adrenergic alpha-Agonists↗
PubMed1998

Fluoxetine induces the transcription of genes encoding c-fos, corticotropin-releasing factor and its type 1 receptor in rat brain.

Fluoxetine is a serotonin re-uptake blocker commonly used to treat endogenous depression. The present experiments were carried out to assess the effects of fluoxetine on c-fos induction throughout the rat brain. In addition, intron-directed in situ hybridization analysis was used to examine fluoxetine regulation of corticotropin-releasing factor heteronuclear gene transcription in the paraventricular nucleus of the hypothalamus. Because the actions of corticotropin-releasing factor are mediated by membrane-bound corticotropin-releasing factor type 1 receptors, we also evaluated the stimulation of such receptors after acute fluoxetine exposure. The immediate-early gene, c-fos, was markedly induced in several telencephalic and diencephalic brain structures. For instance, a strong hybridized signal was apparent 30 min after fluoxetine (10 mg/kg; intraperitoneal) administration in the caudate putamen, septal nucleus, bed nucleus of stria terminalis, anterodorsal preoptic area, paraventricular nucleus, supraoptic nucleus, ventromedial hypothalamus and posterior hypothalamic nucleus. In addition, c-fos-expressing neurons were also evident in discrete amygdaloid nuclei. This nuclear induction was brief in duration, as levels of the immediate-early gene were mostly undetectable 90 min after drug administration. In contrast to the extensive induction of c-fos by fluoxetine throughout the brain parenchyma, elevation of corticotropin-releasing factor heteronuclear RNA levels were confined exclusively to neurosecretory nerve cells of the paraventricular nucleus, with peak levels detected 30 min after fluoxetine exposure. Therefore, the time-course of corticotropin-releasing factor heteronuclear RNA closely paralleled that of c-fos. Significant changes in corticotropin-releasing factor type 1 receptor messenger RNA levels were also observed in the paraventricular nucleus but with a slow incremental biosynthesis of the receptor messenger RNA, as high levels were discernible only 360 min after fluoxetine treatment. Finally, we failed to detect sex-related differences in the acute response to fluoxetine, as both female and male rat brains showed a comparable induction of c-fos, corticotropin-releasing factor heteronuclear RNA and corticotropin-releasing factor type 1 receptor expression within parvocellular neurosecretory nerve cells that govern the stress response. All of these findings are discussed in terms of specific sequences of nuclear events that couple fluoxetine-based serotonin input with changes in gene expression in selective neurons.

Animals↗
PubMed1997

Differential behavioral responses to cocaethylene of Long-Evans and Sprague-Dawley rats: role of serotonin.

Cocaethylene is a neuroactive metabolite derived from the concurrent consumption of cocaine and ethanol. The effects of cocaethylene on locomotor activity, stereotypy, and rearing in Long-Evans and Sprague-Dawley rats were compared. A single cocaine injection (molar equivalent of 60 mumol/kg cocaethylene, intraperitoneal) elicited a robust series of motor output behaviors, including locomotion, stereotypy, and rearing over a 30-minute testing period in Long-Evans rats. In contrast, cocaethylene administration, under comparable testing conditions, produced no significant changes in locomotor and investigatory behaviors. Because cocaethylene has relatively little impact on serotonin (5-HT) reuptake as opposed to reuptake of dopamine, we pretreated Long-Evans rats with fluoxetine (10 mg/kg; i.p.), a selective 5-HT reuptake inhibitor. Fluoxetine profoundly augmented cocaethylene-stimulated behaviors in this rat phenotype. To examine whether other rat strains exhibit a similar response to cocaethylene, Sprague-Dawley rats were injected (i.p.) with cocaethylene and their behavior patterns monitored over a 30-minute testing period. Cocaethylene produced marked locomotor and exploratory behaviors in this strain, suggesting therefore that Long-Evans and Sprague-Dawley rat differ in their response to cocaethylene. To relate these behavioral differences to possible structural differences in the neuronal density of dopaminergic or serotonergic neurons, Long-Evans and Sprague-Dawley brains were evaluated for tyrosine hydroxylase and 5-HT immunocytochemistry. No gross morphological differences in neuronal architecture or density were found in the ventral tegmental area or dorsal raphe nucleus of the two rat phenotypes. These results indicate that two commonly used rat strains show a differential response to cocaethylene and the neurochemical basis for this behavioral difference may be related to synaptic 5-HT bioavailability.

Animals↗
PubMed1997

Expression of the preoptic regulatory factor-1 and -2 genes in rat testis. Developmental and hormonal regulation.

Hormone-responsive peptides play a vital role in development and regulation of testicular function. The preoptic regulatory factors, porf-1 and porf-2, were originally discovered in the rat brain, but are also expressed in the rat and human testis. In the brain expression is age-related, hormone-responsive, region- specific, and gender-related, suggesting that porf-1 and porf-2 are involved in gender-specific brain development and function. Tissue-specific porf-1 and porf-2 mRNAs are also found in the testis and hypophysectomy may alter testicular porf-2 expression. It was thus of interest to further examine porf-1 and porf-2 expression in the testis to evaluate their potential as hormone-responsive peptides that regulate testicular development and function. Testicular expression of both porf-1 and -2 was analyzed as a function of maturational stage, aging and hypophysectomy by the solution hybridization/nuclease protection assay, and cellular location determined by in situ hybridization histochemistry. Expression was quantitatively compared in normal male rats at 15, 30 and 60 d (n = 4) and at 2, 6, 12, and 24 mo of age (n = 5). During development porf-1 is expressed at a constant level at 15, 30 and 60 d, then declines significantly with advancing age; levels at 24 mo are only 20% of those seen at 2 mo (p < 0.05). In contrast, porf-2 expression is highest at 15 d of age and steadily declines at 30 and 60 d, plateaus in the mature adult (6 and 12 mo), then exhibits an additional significant decline in the aged 24 mo animals (6 vs 24 mo, p < 0.05). Hypophysectomy of young adult rats at day 42 results in increased testicular expression 12 d later of both porf-1 (p < 0.05) and porf-2(p < 0.005) compared to intact 54-d-old rats (n = 5). In situ hybridization histochemistry confirms that both porf-1 and porf-2 are expressed in the mature testis at 60 d of age. Porf-2 mRNA is localized to immature germ cells including spermatogonia and primary spermatocytes. Porf-1 mRNA is associated with mature sperm and at low levels in the Sertoli cell cytoplasm surrounding spermatocytes. These data suggest that porf-2 is a pituitary hormone-responsive factor in the developing testis and that both porf-1 and porf-2 have cell-type specific functions in the germ cell compartment of the mature testis

Aging↗
PubMed1997

Dopaminergic and glutamatergic mechanisms mediate the induction of FOS-like protein by cocaethylene.

Cocaethylene is a psychoactive metabolite formed during the combined consumption of cocaine and ethanol. As this metabolite has many properties in common with cocaine, it is conceivable that cocaethylene administration may induce the activity of nuclear transcription factors that regulate the expression of late-response genes. Therefore, the temporal induction of FOS-like protein in rat brain was examined following IP administration of 60 micromol/kg cocaethylene. Immunoreactivity for the protein was detectable at 1 h in striatal neurons and had virtually disappeared 6 h after drug treatment. Administration of specific dopaminergic (SCH-23390; 0.5 mg/kg) and glutamatergic (MK-801; 1 mg/kg) receptor antagonists prior to cocaethylene indicated a significant role for dopamine (D1) and N-methyl-D-aspartate receptor subtypes in mediating the nuclear induction of the aforementioned transcription factor protein. In contrast, no significant effects on FOS-like protein in discrete neurons of the caudate putamen were found when spiradoline (U-62066), a kappa opioid-receptor agonist, was administered either IP (10 mg/kg) or directly (50 nmol) into the brain parenchyma. In addition, we uncovered a differential sensitivity of Long-Evans rats to the behavioral effects of cocaethylene, with the psychoactive metabolite producing significantly less behavioral activity (e.g., locomotion, rearing, and continuous sniffing) than that produced by cocaine (molar equivalent of 60 micromol/kg cocaethylene). These findings indicate both common and disparate effects of cocaethylene and its parent compound, cocaine, on receptor pathways that regulate target alterations in gene expression and drug-induced motor behavior.

Analgesics↗
PubMed1997

Dethroning AZT.

Explore the source record for details and available documents.

Alkynes↗