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Biomedical subjects

M Ruiz

Publications and source records attributed to M Ruiz.

At least 235 records · Page 13Linked to original sources
PubMed1985

Specific [3H]gamma-aminobutyric acid binding to vestibular membranes of the chick inner ear.

To support a postulated neurotransmitter character of gamma-aminobutyric acid (GABA) in the vertebrate vestibule, [3H]GABA binding was measured in a crude membrane preparation of chick inner ear ampullary cristae. In the absence of divalent cations bound [3H]GABA was displaced by unlabeled GABA, muscimol or bicuculline, but it was not displaced by (+/-)-baclofen. A single population of [3H]GABA binding sites with an equilibrium constant of 19.4 nM and a maximum binding capacity of 0.58 pmol/mg protein was found. These results suggest the possible existence of a synaptic GABAA receptor in the chick inner ear membranes and sustain the neurotransmitter role of GABA in the chick vestibule.

Animals↗
PubMed1985

Heterogeneity of thyroxine binding by serum albumins in normal subjects and patients with familial dysalbuminemic hyperthyroxinemia.

The nature and properties of the T4-binding albumins in the sera of normal subjects and patients with the syndrome of familial dysalbuminemic hyperthyroxinemia (FDH) were investigated by means of isoelectric focusing in polyacrylamide gels. Albumins isolated from normal sera and sera of patients with FDH displayed multiple protein bands, with isoelectric points between 4.65 and 5.75, and protein patterns were the same in the two groups. In normal albumin, [125I]T4 was consistently localized in two bands, termed B1 and B2, whose isoelectric points (pIs) were 5.44 +/- 0.03 and 5.31 +/- 0.02 (mean +/- SE), respectively. Occasionally, binding of far smaller proportions of [125I]T4 was seen in two additional bands of lower pI (5.22 +/- 0.03 and 4.97 +/- 0.07), termed B3 and B4, respectively. In FDH albumin, [125I]T4 was also localized in four bands whose PIs were almost identical to those of B1-B4 in normal albumin. In FDH albumin, however, bands corresponding to B1 and B2 bound only a minor fraction of [125I]T4, the great majority being bound by bands corresponding to B3 and B4, especially the latter. Identity of the four T4-binding albumins in normal and FDH albumin was suggested by their virtually identical pIs in both types of albumin, by the emergence or intensification of the B3 band in both after extraction of endogenous T4, and by the finding that an 125I-labeled derivative of T4 used in a commercial one-step assay for serum free T4 was bound by the B4 band in both normal and FDH albumin, though more intensely in the latter. Treatment of FDH albumin with increasing concentrations of dithiothreitol (DTT; 0.1-5.0 mM) caused a progressive loss of [125I]T4 binding by B3 and B4, leaving [125I]T4 bound by B1 or B2, and had little effect on the binding of [125I]T4 by B1 and B2 in normal albumin. These effects of DTT appeared to correlate well with earlier dialysis studies at physiological pH which revealed that the same concentrations of DTT decreased or abolished the high affinity binding of T4 in FDH albumin but had little effect on the residual lower affinity binding of T4 in FDH albumin or that characteristic of normal albumin. These findings suggest that T4 binding patterns evident during isoelectric focusing of albumin at low pH have relevance to binding of T4 by albumins at physiological pH.(ABSTRACT TRUNCATED AT 400 WORDS)

Alkylation↗
PubMed1984

Moxalactam disodium-induced pulmonary hemorrhage.

Fatal pulmonary hemorrhage occurred on the eighth day of moxalactam therapy. No other pharmacologic agent or obvious cause could be attributed to the hemoptysis. Moxalactam-induced pulmonary hemorrhage should be included in the differential diagnosis of an infiltrate when moxalactam is being administered.

Aged↗
PubMed1984

Effects of two different experimental situations of hypothyroidism on serum aldosterone concentration and plasma renin in rats.

When hypothyroidism is induced surgically in early steps of development in the rat, an increase in serum aldosterone concentration (AC), in absence of changes in plasma renin activity (PRA), is observed. In contrast, in propylthiouracil (PTU) induced hypothyroidism, in adult animals, both AC and PRA decrease. Potassium iodide (KI) or triiodo-L-thyronine (T3) administration to thyroidectomized rats restores AC to normal levels, increasing PRA during the latter treatment. A close relationship between AC and plasma renin concentration (PRC) is observed in these experimental situations. The decrease in urinary aldosterone concentration (ACu), and the relation found between AC/ACu ratio and T3 concentration, suggest that metabolic clearance of aldosterone might be related to peripheric T3 levels in thyroidectomized animals, treated with KI or T3. These observations support the hypothesis, previously reported, which suggests different mechanisms involved in the control of aldosterone and renin release during the two different types of hypothyroidism.

Aldosterone↗
PubMed1982

Familial dysalbuminemic hyperthyroxinemia: a syndrome that can be confused with thyrotoxicosis.

We investigated 15 euthyroid patients from eight families with a recently recognized syndrome, familial dysalbuminemic hyperthyroxinemia (FDH), that could be mistaken for thyrotoxicosis. The syndrome is characterized by elevations in serum thyroxine and the free-thyroxine index (FT4l), which are due to an abnormal serum albumin that preferentially binds thyroxine. This albumin has an abnormal binding site with a much greater affinity for thyroxine (relative to its affinity for triiodothyronine) than that of the hormone-binding site on thyroxine-binding globulin. Results of thyrotropin-releasing hormone and thyroid-suppression tests, as well as direct measurements of the free-thyroxine concentration by equilibrium dialysis, are normal in these patients, although the serum triiodothyronine concentration may be slightly elevated. Although its prevalence is uncertain, FDH may be more common than suspected; we have seen 26 cases within the past year.

Adolescent↗
PubMed1982

[Comparison of adsorption capacity for FSH between kaolin and montmorillonite. Biological and immunological activity relation (author's transl)].

The adsorption capacity of urinary FSH has been studied comparatively with kaolin and montmorillonite, a new type of bentonite, never used before in gonadotrophin adsorption. To measure adsorption capacity, two different assay methods were used: bioassay (for biological activity of the kaolin and montmorillonite extracts) and radioimmunoassay (RIA) for the immunological activity of FSH in both extracts. From the present results a biological activity increase was observed in montmorillonite extracts, while no significant differences between immunological activity of FSH were found in either extract. These findings suggest that montmorillonite could replace kaolin in gonadotrophins extraction and purification methods.

Adsorption↗
PubMed1979

N-Chloroacetyl 5-methoxytryptamine (isamide): a selective antagonist of 5-hydroxytryptamine in the rat uterus.

Isamide, the N-chloroacetyl derivative of 5-methoxytryptamine, produced a dose-dependent competitive blockade of uterine contractions in vitro induced by 5-HT. The pA2 value for the 5-HT-isamide interaction was 4.42. The blockade was short-lasting and reversible; after recovery, a dose-dependent increase in the uterine sensitivity to 5-HT was found. The blockade proved to be selective to the 5-HT receptor. The simultaneous application of 5-HT plus isamide partially prevented the 5-HT-induced auto blockade phenomenon. In addition, isamide did not affect the contractile responses of the uterus to oxytocin or bradykinin or the contractile effects of the rat vas deferens to adrenaline.

5-Methoxytryptamine↗
PubMed1975

Reversal of the 6-hydroxydopamine-induced suppression of a CAR by drugs facilitating central catecholaminergic mechanisms.

The intraventricular injection of 6-hydroxydopamine (200 mug) blocked a previously learned conditioned avoidance response (CAR) in rats. The administration of NE, DOPA, amphetamine, phenelzine, desipramine and clonidine induced the reappearance of the CAR. These results are in agreement with current hypotheses on the mechanism of action of 6-hydroxydopamine on the central nervous system.

Amphetamine↗