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Biomedical subjects

S Contreras

Publications and source records attributed to S Contreras.

15 recordsLinked to original sources
PubMed1990

Neurobiology of schizophrenic syndromes.

The development of imaging technologies for investigating the living human brain has expanded knowledge about schizophrenia and is providing clues about biological factors associated with the disorder. Drawing on these and other developments in the last two decades, the authors review selected structural, functional, neurochemical, immunological, and infectious factors associated with the schizophrenic syndrome. Many of the biological alterations reported have also been found in other psychiatric, neurological, and medical conditions; therefore, the findings have little specificity for schizophrenia and in fact support the heterogeneity of the disorder.

Brain↗
PubMed1990

[The pharmacokinetic bases of management with drugs having a narrow therapeutic range].

The growing tendency to measure blood drug levels of patients with different diseases call for understanding of pharmacokinetic basis of this diagnostic tool. The article is focused on the pharmacological basis of drug use, as well as on factors involved in pharmacokinetic variations related to clinical picture and biological condition of the patient. Processes regulating drug entry and drug release to and from the general circulation are discussed in the context of disease pathophysiology.

Absorption↗
PubMed1988

Calcium function in affective disorders and healthy controls.

Calcium metabolism has been reported to be disturbed in some forms of affective disorder. We studied concurrently a battery of calcium measures in 29 unipolar, 14 bipolar depressed, 11 manic, and 10 healthy control subjects. In addition to measures of extracellular calcium, we studied intracellular calcium concentration in platelets and measures that reflect cellular capability to maintain a low intracellular Ca++ concentration in red blood cells (RBCs) and platelets. Plasma calcium was lower in unipolar and manic patients than in control subjects. Platelet calcium concentration was lower in unipolar than bipolar depressed patients. RBC Ca++ adenosine triphosphatase (ATPase) was lower in unipolar and control subjects than in bipolar depressed and manic patients. Platelet Ca++ ATPase and Ca++ uptake were inversely correlated with severity of illness in unipolar patients. In bipolar depressed patients, RBC Ca++ ATPase and platelet Ca++ uptake were inversely correlated with severity. In addition to indicating abnormalities in calcium activity in affective disorders, the data suggest that unipolar and bipolar patients differ in several measures and may have different pathophysiological disturbances in calcium metabolism.

Adult↗
PubMed1988

Growth of rat osteoblast-like cells in a lipid-enriched culture medium and regulation of function by parathyroid hormone and 1,25-dihydroxyvitamin D.

To examine the role of lipid metabolism in the growth and function of osteoblast-like cells, we studied ROS 17/2.8 osteosarcoma cells and primary cultures of rat calvarial osteoblasts during growth in a serum-free medium supplemented by purified human lipoproteins or by liposomes. Increase in ROS cell number was measured in sparse (1-5 X 10(3)/cm2) cultures over 6-8 days. Liposomes (0-300 micrograms/ml) and high (HDL), low (LDL), and very low density (VLDL) lipoprotein fractions (0-300 micrograms apoprotein) markedly stimulated cell growth. Cells plated at 5 X 10(3)/cm2 achieved growth rates in the presence of LDL or HDL comparable to 10% fetal bovine serum. Serum-free culture with exogenous lipid maintained the response of cell cyclic AMP accumulation to parathyroid hormone. Cyclic AMP response to parathyroid hormone was enhanced by glucocorticosteroid, and was attenuated by 1,25-dihydroxyvitamin D (1,25(OH)2D) with an EC50 (10(-10) M) comparable to that previously observed in serum-cultured cells (J. Biol. Chem. 258:736, 1985). 1,25(OH)2D also increased the alkaline phosphatase activity in ROS cells cultured in lipid-supplemented serum-free culture. Lipoproteins or liposomes also markedly enhanced the proliferative response of sparse cultures of normal rat osteoblasts to polypeptide mitogens.

Animals↗
PubMed1987

Effects of alpha-methylparatyrosine on voluntary consumption of ethanol, water, and solid food in UChA and UChB rats.

The effect of daily doses of 80 mg/kg (intraperitoneal) of alpha-methylparatyrosine, AMPT (inhibitor of tyrosine hydroxylase) on the voluntary consumption of ethanol, water, and solid food was studied in rats of both sexes belonging to the UChA (lower ethanol consumer) and UChB (high ethanol consumer) strains. The consumptions during the treatment period were compared to those of the preceding one (basic). Decrease of ethanol and solid food intake and increase of that of water in UChB rats and only a decrease of solid food intake in UChA rats were observed. These effects cannot be ascribed to blocking of dopaminergic or noradrenergic synapses, since this dose of AMPT inhibits the in vivo synthesis of both catecholamines.

Alcohol Drinking↗
PubMed1987

Neuroleptic radioreceptor activity and clinical outcome in schizophrenia.

The relationship between serum haloperidol concentration and clinical response was examined in 27 schizophrenic inpatients between the ages of 18 and 56 years. All patients were treated with haloperidol, 20 mg/day for the first 2 weeks. Dosage adjustment after 2 weeks of treatment was made in seven subjects based on poor clinical response or side effects. Haloperidol activity was determined by the radioreceptor assay for neuroleptics on weeks 2 and 4 serum samples. The results indicated that higher radioreceptor activity levels, particularly above 22 ng/ml, were associated with poorer clinical response. The data suggest that radioreceptor activity levels are not at a steady state after 2 weeks drug treatment. Additionally, problems secondary to low sensitivity of the radioreceptor assay may limit its utility at low serum concentrations.

Adolescent↗
PubMed1984

Biological similarities and differences between rats genetically different in alcohol preference.

This paper is an inventory of some behavioural, biochemical and pharmacological similarities and differences between two inbred strains of Wistar rats differing in voluntary consumption of ethanol, namely: UChA and UChB with low and high preferences respectively for ethanol under conditions involving free choice between a 10% (v/v) ethanol solution and distilled water. The following strain differences were observed: ethanol consumption (UChA less than UChB); total water consumption (UChA less than UChB); solid food consumption (UChA greater than UChB); rate of recovery of ethanol label in expired CO2 (UChA less than UChB); oxidation of ethanol to acetaldehyde by brain homogenates (UChA greater than UChB); acetaldehyde disposal by brain homogenates (UChA less than UChB); ethanol (90 mmol/kg, i.p.) sleeping-time (UChA less than UChB); chronic and acute tolerance to ethanol (UChA developed it, whereas UChB did not); lethal doses of ethanol (UChA greater than UChB); recovery rate of the label of gluconate in expired CO2 (UChA less than UChB); recovery rate of the label of fructose in expired CO2 (UChA less than UChB); blood-glucose level after glucose (1 g/kg, i.p.) load (UChA less than UChB). No strain differences were observed in the rate of recovery in expired CO2 of the label of the following substrates: acetate, pyruvate, butyrate, citrate, ribose, glycerol, sorbitol, glucose and galactose.

Alcoholic Intoxication↗
PubMedDate not supplied

Effects of pyrazole on the voluntary consumption of ethanol, water and solid food in UChA and UChB rats.

The effect of pyrazole (35 or 70 mg/kg IP) on the voluntary consumption of ethanol, water and solid food was studied in UChA (genetically low ethanol consumer) and UChB (genetically high ethanol consumer) rats of both sexes, under a free choice of 10% v/v ethanol solution, distilled water and solid food. the data were analyzed according to the method previously proposed for recognizing the specific effect on appetite-satiety of ethanol. The effect of pyrazole in UChB rats correlated with the pattern of specific effects on appetite-satiety for ethanol. The only effect observed in UChA rats was a decrease in the intake of solid food and total water. No significant sex differences were observed.

Alcohol Drinking↗
PubMedDate not supplied

A method for recognizing specific effects on ethanol intake by experimental animals.

A method of mathematical treatment of data concerning changes in voluntary consumption of ethanol solution, water and solid food, induced by experimental treatments in animals, in order to recognize effects on mechanisms involved in specific appetite and satiety for calories, water and ethanol is proposed. The need of such method arises from the fact that several experimental treatments tested by the effects on ethanol consumption alter at the same time the appetite or satiety for calories and/or for water, as well as ingestive behavior. The results of testing the method with the data obtained by treatment of UChA and UChB rats with disulfiram or cyanamide were consistent with the expected ones.

Alcohol Drinking↗
PubMedDate not supplied

Effects of p-chlorophenylalanine on the voluntary consumption of ethanol, water and solid food by UChA and UChB rats.

The immediate and the long-lasting effects of PCPA (126 mg/kg IP for 3 days) on the voluntary consumption of 10% v/v ethanol solution, water and solid food were studied in genetically low (UChA) and high (UChB) ethanol consumer rats. Data were analysed according to the method proposed by the authors for recognizing specific effects on ethanol consumption. Results confirmed immediate specific decrease of ethanol consumption in UChB rats, while a nonspecific decrease of it was observed in UChA rats. In UChB rats ethanol consumption recovered the basic level about nine days after the first dose. By contradistincion, in UChA rats a significant specific increase of ethanol consumption, starting at the first week after the treatment, was observed. During this period 12 out of 21 UChA rats reached an ethanol consumption level commonly observed in UChB rats, and 10 of them recovered the pretreatment level in 15 to 30 weeks. The other 2 maintained the high consumption until 38 weeks of observation. At that time the serotonin content of cortex and hippocampus of these 2 rats was normal.

Alcohol Drinking↗
PubMedDate not supplied

Effects of serotonin uptake blockers and of 5-hydroxytryptophan on the voluntary consumption of ethanol, water and solid food by UChA and UChB rats.

The effects of zimelidine, fluvoxamine, and citalopram (serotonin uptake blockers), as well as those of 5-hydroxytryptophan (serotonin precursor), on the voluntary consumption of 10% ethanol solution, distilled water and solid food were tested in UChA (genetically low ethanol consumer) and UChB (genetically high ethanol consumer) rats. Since it is well known that drugs which stimulate central serotonergic synapses decrease food and water intake, the data concerning the difference of the respective consumption during the treatment period and the pretreatment one were analysed with a method previously proposed (Alcohol 5:15-19; 1988) to recognize specific effects on ethanol intake. The results showed that while the decrease of ethanol consumption induced by the three serotonin uptake blockers appeared not to be specific of ethanol, the effects of 5-hydroxytryptophan in UChB rats satisfy the criteria for being considered as an expression of a decrease of the specific appetite--or increase satiety--for ethanol. Experimental results cannot help in the explanation of this difference.

5-Hydroxytryptophan↗