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Biomedical subjects

M Pinto

Publications and source records attributed to M Pinto.

At least 127 records · Page 7Linked to original sources
PubMed1975

Dose-response study of the inhibiting effect of somatostatin on growth hormone and insulin secretion in normal subjects and acromegalic patients.

A dose-response study of the effect of somatostatin on plasma growth hormone (GH) and immunoreactive insulin (IRI) levels was performed in normal subjects and acromegalic patients. In normal subjects 150 mug of somatostatin completly suppressed GH and IRI responses to arginine, while with 75 and 37.5 mug only a partial suppression was usually observed. Basal levels of plasma IRI were significantly lowered within 15 min from the start of somatostatin injection at each of the three dose levels. In three acromegalics the doses of 150 and 75 mug of somatostatin were effective in lowering both GH and IRI levels; the dose of 37.5 mug was still effective in lowering plasma IRI levels, while GH levels were not significantly modified. A dose of somatostatin inhibiting GH secretion without affecting insulin secretion has not been found either in acromegalics and in normals. It was concluded that the effects of somatostatin on GH and IRI secretion cannot be easily dissociated.

Acromegaly↗
PubMed1975

Inhibition of ACTH response to oral and intravenous metyrapone by antiserotoninergic treatment in man.

Plasma ACTH levels after oral and iv metyrapone administration were studied in 7 and 5 healthy women respectively both under basal conditions and after a 4-day treatment with metergoline, a specific antiserotoninergic agent. In 3 additional women, the effects of methysergide, another antiserotoninergic drug, on the plasma ACTH rise induced by oral metyrapone, were evaluated. A significant lowering of the plasma ACTH levels attained after either oral or iv metyrapone was observed following metergoline administration: 149+/-64.3 vs 239+/-49.1 pg/ml (mean peak values), P less than 0.05 in the oral test and 331+/-19.7 vs 221+/-19.5 pg/ml, P less than 0.02 in the iv test. The fall of plasma cortisol caused by metyrapone was comparable before and after the antiserotoninergic treatment. An interference of metergoline in the ACTH radioimmunoassay was also excluded. After metergoline administration, a slight reduction in the baseline plasma ACTH values was noted: 79+/-7.7 vs 67+/-7.7 pg/ml (NS). A decrease, however not statistically significant, of the metyrapone-induced plasma ACTH elevation occured after methysergide administration: 421+/-150.7 vs 344+/-135.1 pg/ml. These results can be interpreted as indicating that antiserotoninergic treatment caused an inhibition of hypophysial ACTH release in response to metyrapone. Caution is recommended, however, before concluding, on the basis of these findings, that serotonin as such plays a physiological stimulating role on ACTH secretion.

Administration, Oral↗
PubMed1975

Ethidium bromide mutagenesis in yeast: protection by anaerobiosis.

The mutagenesis by ethidium bromide, an intercalating dye, which induces the mutation from wild type (rho+) to the cytoplasmic respiratory deficient petite (rho-) in Saccharomyces cerevisiae, was studied under aerobic and anaerobic conditions. During growth of anaerobic cells at pH 6.5, ethidium bromide at a concentration of 2 mug/ml is unable to induce rho- mutants whereas under aerobic conditions the entire population is converted into rho- cells within 1 generation at the same drug concentration. With ethidium bromide 10 mug/ml 98% of the anaerobic cells are transformed into rho- in 5.5 h (more than 2 generations). In non-growing conditions, ethidium bromide 10 mug/ml has no effect in anaerobic cells. 3 h adapted cells used as control, are converted into rho- in 8 h. Increasing the ethidium bromide concentration to 20 mug/ml resulted in the appearance of some rho- mutants in the anaerobic population but marked at the same time the onset of a detectable toxic effect of the drug.

Aerobiosis↗
PubMed1975

[Changes in the secretion of somatotropin and insulin in hyperthyroidism].

Twenty hyperthyroid patients were investigated for growth hormone (GH) and immunoreactive insulin (IRI) secretion in response to insulin hypoglycaemia, arginine infusion and glucose-induced hyperglycaemia. GH response to either insulin hypoglycaemia or arginine infusion was significantly reduced in these patients compared with 20 normal subjects. Thyrotoxic patients also displayed an abnormal GH pattern after a 100 g oral glucose load: in fact, serum GH underwent a paradoxical increase in spite of abnormally high levels attained by blood glucose. IRI secretion was also clearly reduced in response to arginine infusion and moderately blunted after oral glucose. In a group of patients re-evaluated under euthyroid conditions, a fair increase of GH response to the provocative stimuli jointly with the restoration of a normal suppressibility of serum GH by glucose were noted; by contrast, no significant change of IRI response to arginine or glucose took place. Likewise, the impairment of glucose tolerance was not improved. These findings indicate that an impairment of GH and IRI secretion is present in hyperthyroidism. The possibility that a potentiation of the catecholamine effects caused by the thyroid hormones is involved in this alteration deserves consideration.

Adult↗
PubMed1975

Specific unresponsiveness to skin allografts in mice. IV. Immunological reactivity of mice treated with liver extracts, Bordetella pertussis, and antilymphocyte serum.

The strain-specific unresponsiveness to H-2 incompatible skin allografts induced by treatment of adult mice with single inoculations of donor strain liver extract and Bordetella pertussis vaccine, as well as three doses of antilymphocyte serum, has been investigated by several in vivo and in vitro methods, with a view to elucidating it mechanism. Lymphoid cells from mice with long surviving skin grafts were found to be reactive in graft-versus-host assays (as measured by splenomegaly or popliteal lymph node enlargement), and mixed lymphocyte culture tests gave positive results. Attempts to cause lethal runting of F1 hybrid mice injected at birth with spleen cells from unresponsive mice gave variable results. However, the injection of F1 hybrid cells into the footpads of unresponsive animals failed to elicit a significant host-versus-graft response. Although lymphoid cells from unresponsive animals did not include detectable numbers of cytotoxic cells, such cells could be generated by previous in vitro mixed lymphocyte culture stimulation or, to some degree, by the injection of the animals with F1 hybrid cells. Attempts to prevent mixed lymphocyte culture stimulation or cytotoxicity with serum from unresponsive mice failed at the serum concentrations used. The data indicate that long-term unresponsiveness in this system is maintained by the production in the hosts of factors that interfere with the cell-mediated response.

Animals↗