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Biomedical subjects

M K Jones

Publications and source records attributed to M K Jones.

At least 163 records · Page 9Linked to original sources
PubMed1981

The effect of propranolol on thyroid hormones in T3 toxicosis.

Serum thyroid hormone concentrations were measured before and during 6 months treatment with propranolol (160 mg/day) in eight patients with T3 (triiodothyronine) toxicosis. Serum total T3 concentrations showed a significant (p less than 0.01) and sustained fall to approximately 80% of pre-treatment values. Six of the patients, however, remained clinically and biochemically hyperthyroid and our data do not support the use of propranolol as sole therapy in T3 toxicosis.

Aged↗
PubMed1981

Studies on apparent free cortisol and testosterone in plasma from patients with breast tumours.

The concentrations of cortisol and testosterone (total and apparent free) in peripheral venous plasma were measured in 147 women. The results showed that there were no significant differences in concentrations between women with normal breasts, those with histologically confirmed benign or malignant breast tumours and those with cancer at other sites. There was, however, a significant increase with age in the concentrations of total (P less than 0.005) and apparent free (P less than 0.02) cortisol.

Adult↗
PubMed1981

Beta-adrenoreceptor blocking drugs and thyroid hormones in hyperthyroid subjects.

Serum thyroid hormone concentrations were measured before and during 10 days' treatment with atenolol (200 mg/day), acebutolol (400 mg/day), oxprenolol (160 mg/day) and propranolol (160 mg/day) in 24 hyperthyroid patients. During propranolol treatment serum triiodothyronine (T3) concentrations fell significantly (P less than 0.05) but there was no change in thyroid hormone concentrations in the other groups although all patients reported a symptomatic improvement.

Adrenergic beta-Antagonists↗
PubMed1981

The reproducibility of serial meal and oral glucose tolerance tests in normal subjects.

Five normal volunteer subjects within 10% of their ideal body weight received four isocaloric meals per day during two separate study periods. Each study period consisted of two consecutive days one week apart. The plasma glucose and insulin response was determined half-hourly throughout the second day of each of the two study periods. Good reproducibility of the glucose and insulin response to the standardised meals on the two comparative profile days was observed. Only at three points during the day was the plasma glucose significantly different between the profile days while no differences existed for plasma insulin. In addition, a separate group of four healthy normal volunteer subjects within 10% of their ideal body weight received four 50 g oral glucose tolerance tests on each of four days, ie on two consecutive days one week apart. During the second day of each study period half-hourly plasma glucose and insulin concentrations were determined. The within subject reproducibility of the plasma glucose and insulin response to the serial glucose loads was excellent. At one time point only was the mean plasma glucose for the group significantly different between the two study days. No statistically significant difference however was observed for the plasma insulin response between the two days. As the day progressed during both test procedures a small decrease in carbohydrate tolerance was observed. The amplitude of glycaemic excursions in response to the oral glucose tolerance tests was greater than that observed in response to the meal tolerance tests.

Blood Glucose↗
PubMed1980

Regulation of ornithine decarboxylase activity by amino acids, cyclic AMP and luteinizing hormone in cultured mammalian cells.

Any one of five amino acis (alanine, asparagine, glutamine, glycine, and serine) is an essential requirement for the induction of ornithine decarboxylase (EC 4.1.1.17) in cultured chinese hamster ovary (CHO) cells maintained with a salts/glucose, medium. Each of these amino acids induced a striking activation of ornithine decarboxylase in the presence of dibutyryl cyclic AMP and luteinizing hormone. The effect of the other amino acids was considerably less or negligible. The active amino acids at optimal concentrations (10 mM) induced only a 10-20 fold enhancement of enzyme activity alone, while in the presence of dibutyryl cyclic AMP, ornithine decarboxylase activity was increased 40-50 fold within 7-8 h. Of the hormones and drugs tested, luteinizing hormone resulted in the highest (300-500 fold) induction of ornithine decarboxylase with optimal concentrations of dibutyryl cyclic AMP and asparagnine. Omission of dibutyryl cyclic AMP reduced this maximal activation to one half while optimal levels of luteinizing hormone alone caused no enhancement of ornithine decarboxylase activity. The induction of ornithine decarboxylase elicited by dibutyryl cyclic AMP, amino acid and luteinizing hormone was diminished about 50% with inhibitors of RNA and protein synthesis. The specific amino acid requirements for ornithine decarboxylase induction in chinese hamster ovary cells was similar to the requirements for induction in two other transformed cell lines. Understanding the mechanism of enzyme induction requires an identification of the essential components of the regulatory system. The essential requirement for enzyme induction is one of five amino acids. The induction of ornithine decarboxylase by dibutyryl cyclic AMP and luteinizing hormone was additive in the presence of an active amino acid.

Amino Acids↗
PubMed1980

The effect of propranolol withdrawal on thyroid hormones in normal and hyperthyroid subjects.

Blood thyroid hormone levels were measured during, and for 6 days after, treatment with propranolol (160 mg/day, 4-8 weeks) in five hyperthyroid patients and six normal volunteers. In hyperthyroid patients triiodothyronine (T3) and free triiodothyronine index (FT3I) rose to peak levels 60 h after propranolol withdrawal without significant change in thyroxine (T4) or Thyopac-3 test. In normal subjects no significant change in thyroid hormone levels was seen during propranolol treatment or withdrawal. The rise in T3 and FT3I coincides with, and may contribute to, the rebound increase in adrenergic activity after propranolol withdrawal in hyperthyroidism.

Adult↗
PubMed1980

The effect of oxprenolol, acebutolol and propranolol on thyroid hormones in hyperthyroid subjects.

Serum thyroid hormone levels were measured before and during 10 days treatment with acebutolol (400 mg/day), oxprenolol (160 mg/day) and propranolol (160 mg/day) eighteen hyperthyroid patients. A significant change in thyroid hormone concentrations was seen only in the group treated with propranolol. Propranolol should be used in preference to beta-adrenoreceptor blocking drugs with partial agonist activity, in the treatment of hyperthyroidism.

Acebutolol↗
PubMed1979

Control of hypercalcaemia in thyrotoxicosis.

Two thyrotoxic patients with significant hypercalcaemia are described. The hypercalcaemia failed to suppress with hydrocortisone, propranolol and calcitonin but serum calcium fell rapidly to normal with carbimazole treatment. Both patients were subsequently treated surgically and at operation no evidence of parathyroid disease was found. Thyroid disease must be controlled before co-existing parathyroid disease is diagnosed in hypercalcaemic thyrotoxic patients.

Adult↗
PubMed1978

The effect of low dose carbidopa/levodopa on prolactin and growth hormone concentrations in patients with breast cancer and in benign breast tumours.

1 Low doses of carbidopa/levodopa (12.5 mg 1-alpha-methyl-dopahydrazine, 125 mg levodopa) were administered orally to 29 patients with tumours of the breast (16 with breast cancer, 13 with benign breast disease). 2 Plasma dopa response curves were similar in all the patients studied. 3 Prolactin and growth hormone showed similar responses to carbidopa/levodopa irrespective of age or diagnosis. 4 Prolactin showed an unusual reponse in four patients which has not previously been recorded.

Adult↗