Biomedical subjects

B Roca

Publications and source records attributed to B Roca.

84 records · Page 5Linked to original sources

PubMed1986

Evidence for somatostatin binding sites in rabbit kidney.

Specific binding sites for somatostatin have been identified in cytosolic fraction of rabbit kidney (cortex and outer medulla) using 125I-Tyr11-somatostatin. The binding was saturable and reversible, as well as time and temperature dependent. Optimal pH for binding was observed at about 7.4. Scatchard plots were compatible with the existence of two classes of binding sites: a first class with a high affinity (Kd = 40 nM) and a low binding capacity (2.0 pmol somatostatin/mg protein) and a second class with a low affinity (Kd = 222 nM) and a high binding capacity (114.3 pmol somatostatin/mg protein). Vasoactive intestinal peptide, neurotensin, substance P, Leu-enkephalin and vasopressin had practically no effect on somatostatin binding. The properties of these binding sites strongly support the concept that somatostatin could behave as a regulatory peptide on the rabbit kidney.

Animals↗

PubMed1986

Involvement of cyclic AMP-dependent protein kinase on the phosphorylase kinase inhibition by glucose-6-phosphate in adipose tissue extracts.

In order to achieve further clarification of the regulation of glycogenolysis in adipose tissue, we studied the effect of glucose-6-phosphate on phosphorylase activation in Sephadex G-25 filtrate of adipose tissue. The activity of phosphorylase kinase was decreased by 50% and by 75% in the presence of 0.5 mM and 2 mM of glucose-6-phosphate, respectively. This inhibition could be partially prevented by 0.5 mM AMP. Furthermore, we investigated the influence of glucose-6-phosphate on the effect of cyclic-AMP-dependent protein kinase on the activation of phosphorylase. The addition of cyclic-AMP and cyclic-AMP-dependent protein kinase caused a decrease in the inhibition of the phosphorylase activation by glucose-6-phosphate. Also, the glucose-6-phosphate at physiological concentration, decreased adipose tissue cyclic-AMP-dependent protein kinase activity.

Adenosine Monophosphate↗

PubMed1981

Cyclic AMP-dependent protein kinase activity and lipolysis in adipose tissue. Effect of fasting, oligomycin and iodoacetamide.

The release of glycerol into the medium, the concentration of cAMP, and the cAMP-dependent protein-kinase activity were studied in adipocytes and in fat-pads obtained from epididymal adipose tissue of rats under different conditions of feeding. An increase in the tissue concentration of cAMP and in the protein-kinase activity was observed in vivo at 48 and 96 h of fasting. A diminished release of glycerol was found in adipocytes from rats fasted for 48 h, in the absence of glucose, and the maximum concentration of cAMP was inferior to that of fed rats. Oligomycin and iodoacetamide, in the presence of epinephrine and glucose, produce a diminution in the values of the parameters studied. No significant differences were observed, however, in the responses of tissue obtained from fed and fasting rats to these compounds. The present results confirm previous observations and show the dependence of the lipolytic process on carbohydrate metabolism.

Adipose Tissue↗

PubMedDate not supplied

Interaction of somatostatin with isolated cytosol from rabbit renal papilla.

Specific binding sites for somatostatin have been characterized in cytosolic fraction of rabbit renal papilla. The interaction of 125I-Tyr11-somatostatin with cytosolic fraction was rapid, reversible, specific, saturable and dependent on temperature. At 25 degrees C the binding data were compatible with the existence of two classes of binding sites: a high-affinity class with a Kd = 57.7 nM and a low-affinity class with a Kd = 217.4 nM. Somatostatin binding sites exhibited a high degree of specificity since neuropeptides such as Leu-enkephalin, neurotensin, substance P, vasopressin and vasoactive intestinal peptide behaved as ligands with null or very low affinity.

Animals↗

PubMedDate not supplied

Modification of somatostatin content and binding in jejunum from celiac children.

The concentration of somatostatin was studied in controls as well as in plasma and jejunal mucosa from celiac children with and without jejunal villous atrophy. The binding of somatostatin to cytosolic fraction, isolated from jejunal mucosa from celiac patients and controls, was also investigated. Fasting plasma somatostatin concentrations were not significantly different among the various groups studied. However, the jejunal somatostatin content was significantly higher in the group of celiac children with subtotal villous atrophy as compared to control group and celiac children with normal villous architecture. The binding of somatostatin to cytosol of jejunal mucosa was significantly decreased in the group of celiac children with subtotal villous atrophy. The present results suggest that somatostatin may be involved in the pathophysiological processes of celiac disease.

Binding Sites↗

PubMedDate not supplied

[Enterobacter cloacae related meningitis].

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Adult↗

PubMedDate not supplied

Air apple-core-like narrowing of the dilated transverse colon.

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Adenocarcinoma↗

PubMedDate not supplied

[Leptospirosis].

Leptospirosis is the most common zoonosis worldwide, although most cases occur in tropical countries. Leptospira interrogans, a spirochete, is the causative agent. Rats are the main reservoir. Most patients present a mild clinical form of the disease, which consists of a self-limited febrile process, without jaundice. Nevertheless, about 10% of patients suffer severe infections, with intense jaundice. Typically the disease manifests in two phases: acute or leptospiremic and immune or leptospiuric, although in many patients the two phases are indistinguishable, and in mild cases the second one is frequently absent. Diagnosis is carried out by serology or culture of the microorganism. Treatment consists of antibiotics such as penicillin G, ceftriaxone, doxycycline or amoxicillin.

Humans↗

PubMedDate not supplied