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Biomedical subjects

J Landon

Publications and source records attributed to J Landon.

At least 181 records · Page 10Linked to original sources
PubMed1969

Influence of amphetamines on plasma corticosteroid and growth hormone levels in man.

Plasma fluorogenic corticosteroid and immunoreactive growth hormone levels rose significantly after the intravenous administration of methylamphetamine to healthy young men at various times of the day. The rise in corticosteroids was most pronounced in the evening and was accompanied by an increase in circulating levels of immunoreactive corticotrophin. Oral dexamphetamine also resulted in significant rises in plasma corticosteroids but not in growth hormone. These hormonal changes were accompanied by evidence of mild central stimulation. Though they may be part of an associated and non-specific response, it is more likely that they represent specific effects of amphetamines on centres in the hypothalamus or midbrain controlling secretion of corticotrophin and growth hormone releasing factors.

Adrenal Cortex Hormones↗
PubMed1969

The small-scale isolation and characterization of adrenocorticotrophin.

Several methods for isolating adrenocorticotrophin from small quantities of porcine and bovine pituitary tissue are compared. Initial extraction of the hormone by an acid-acetone technique was simpler and more efficient than one employing acetic acid extraction and ether precipitation. Subsequent purification procedures utilizing adsorption of the peptide on to oxycellulose realized the highest yields. CM-cellulose-column chromatography followed by Sephadex-gel filtration were suitable final steps for obtaining highly purified adrenocorticotrophin. The purity of the hormone was demonstrated by determining its amino acid composition, C-terminal analysis, polyacrylamide-gel electrophoresis, chymotrypsin digestion and paper electrophoresis and by radioimmunoassay and bioassay. Adrenocorticotrophin was found to be rapidly destroyed in intact and especially in homogenized glands kept at room temperature. At 4 degrees the rate of destruction was less rapid and at -20 degrees losses were minimal.

Adrenocorticotropic Hormone↗
PubMed1968

Plasma levels of immunoreactive corticotrophin in patients with Cushing's syndrome.

Plasma levels of immunoreactive corticotrophin (A.C.T.H.) have been determined in 56 patients with Cushing's syndrome by means of a homologous radioimmunoassay. In untreated Cushing's disease (bilateral adrenal hyperplasia due to excessive A.C.T.H. secretion from the pituitary) plasma values ranged from 40 to 200 mumug./ml., between 8 and 10 a.m., compared with a range in normal subjects of 12 to 60 mumug./ml. Considerably raised levels, often above 2,000 mumug./ml., were found in patients with Cushing's disease after bilateral adrenalectomy. A.C.T.H. concentrations were usually higher in patients with bilateral adrenal hyperplasia associated with ectopic A.C.T.H. production than in patients with untreated Cushing's disease; whereas plasma A.C.T.H. was undetectable in the presence of an adrenocortical tumour. All patients with Cushing's syndrome failed to show the normal circadian rhythm of circulating A.C.T.H. levels.

Adrenal Gland Neoplasms↗