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Biomedical subjects

J L Touber

Publications and source records attributed to J L Touber.

At least 37 records · Page 2Linked to original sources
PubMed1979

Propranolol inhibits the in vitro conversion of thyroxine into triiodothyronine by isolated rat liver parenchymal cells.

A model for the in vitro study of the conversion of thyroxine into triiodothyronine using isolated rat liver parenchymal cells is described. Isolated liver cells (mean protein content 18 mg/ml) convert approximately 0.8% of 1.3 microM exogenously added T4 into T3 during thirty minutes incubation. Carbimazole (50 microM) has no effect on the conversion process, whereas propylthiouracil (50 microM) inhibits the conversion. The beta-adrenoceptor blocking agent propranolol lowers the conversion ratio when added in concentrations of 580 and 1160 microM, but has no inhibitory effect when 290 microM is added.

Animals↗
PubMed1978

Protein hormones in cerebrospinal fluid: evidence for retrograde transport of prolactin from the pituitary to the brain in man.

Plasma and cerebrospinal fluid (CSF) levels of two hormones of similar molecular size, pituitary prolactin (PRL) and human chorionic somatomammotropin (hCS), and of the bigger hormone human chorionic gonadotropin (hCG) were measured in six pregnant women without pituitary disease. For all three hormones, the plasma and CSF levels were closely correlated. The plasma/CSF concentration ratio for hCG (571 +/- 378, mean +/- SD) was significantly different (P less than 0.01) from the hCS ratio (24.6 +/- 6.1); the hCS ratio was significantly different (P less than 0.005) from the PRL ratio (7.2 +/- 1.5). We conclude that (1) the CSF concentration of a protein hormone depends on the plasma concentration and on its molecular size, and (2) pituitary hormones reach the CSF not only via filtration of peripheral blood at the choroid plexuses, but also more directly via retrograde transport from the pituitary to the brain.

Biological Transport↗
PubMed1978

Modulation of gastrin release by acute changes in plasma calcium.

Gastrin release was studied in 5 hypergastrinemic patients, both during calcium infusion and EDTA infusion. In each patient, gastrin decreased in conjunction with the fall in plasma calcium, and increased during calcium infusion. Plasma gastrin and calcium levels were strongly correlated.

Achlorhydria↗
PubMed1978

Prolactin in human cerebrospinal fluid.

PRL was measured radioimmunologically in plasma and cerebrospinal fluid (CSF) samples obtained simultaneously in 31 patients with various neurological or infectious, but non-endocrine diseases (group A), 12 patients (7 pregnant women and 5 newborns) with physiological hyperprolactinemia (group B),10 psychiatric patients with pharmacologically induced hyperprolactinemia (group C) 12 normoprolactinemic patients with pituitary adenoma and suprasellar extension (SSE) (group D), And 14 hyperprolactinemic patients with pituitary adenoma with and without SSE (group E). Plasma PRL and CSF PRL concentrations (ng/ml, mean and range in brackets) of the various groups were: group A, 6.2 (1.3-14.5) and 1.3 (0.6-4.7); group B, 85.2 (31-200) and 13.2 (3-28); group C, 54.3 (3.5-160) and 6.5 (0.7-18); group D, 17.2 (5.4-30) and 9.7 (2.7-34); and group E, 2,529 (115-10,000) and 1,449 (6-13,000). The plasma to CSF concentration ratios (mean and range in brackets) were: group A, 5.2 (1.4-13.0); group B, 7.0 (2.9-10.3); group C, 7.3( 3.9-11.3); group D, 2.6 (0.9-7.1); and group E, 10.9 (0.2-34.9). The ratio was greater than 3 in 87% of the non-tumor patients; in 42% of the tumor patients the ratio was less than 3. The correlation between plasma and CSF PRL levels of all 53 subjects without a pituitary tumor (groups A, B, and C) was positive (r=0.9097; P=0.00001); in the 26 tumor patients (groups D and E) the correlation was also positive (r=0.7141; P=0.00002). These results indicate that 1) PRL is a normal constituent of CSF, 2) the CSF PRL level is a function of the plasma level, 3) detectable, or even high, CSF PRL levels per se are not indicative in the presence of a pituitary tumor, with or without SSE, and 4) abnormally low ratios may be found in patients with a pituitary tumor with SSE.

Adenoma↗
PubMed1977

The influence of beta-adrenoceptor blocking agents on plasma thyroxine and triiodothyronine.

The effect of the beta-adrenoceptor blocking agent propranolol on plasma levels of thyroxine and triiodothyronine was studied in eleven hyperthyroid patients and in six hypothyroid patients on L-thyroxine substitution therapy. In all patients a decrease in plasma-triiodothyronine was found. The per cent decrease of plasma-triiodothyronine was the same in both groups. Plasma levels of thyroxine and thyrotropin increased in the hypothyroid patients, but remained constant in the hyperthyroid subjects. The decrease in plasma-triiodothyronine during propranolol medication is most likely caused by an inhibition of the peripheral conversion of thyroxine into triiodothyronine.

Adult↗
PubMed1977

Orphenadrine (Disipal), serum thyroxine and thyroid function.

Studies were undertaken to elucidate whether orphenadrine influences thyroid function. Seven volunteers were given orphenadrine in weekly increasing dosage up to 300 mg per day; in 5 patients chronically treated with 300 mg orphenadrine daily the drug was gradually discontinued. No changes were found in PBI, RT3U, TT3 and TSH during or after orphenadrine medication; also TSH- and TT3-responses to 200 microgram TRH iv were not influenced by the drug. Orphenadrine medication increased serum thyroxine values (P less than 0.001) as measured with the competitive protein binding (CPB) technique, but did not influence serum thyroxine values measured by radioimmunoassay. Orphenadrine added to serum in vitro in the Murphy-Pattee assay did not increase thyroxine values; two out of eight tested metabolites however did. It is concluded that orphenadrine in a dosage up to 300 mg per day does not influence thyroid function. It increases serum thyroxine levels as measured by the competitive protein binding technique of Murphy and Pattee. This is due to an in vitro competition between ethanol-extractable orphenadrine metabolites and thyroxine for binding sites on the thyroxine binding globulin.

Binding, Competitive↗
PubMed1974

Original articles.

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Adenoma, Chromophobe↗