ABSTRACT
A 13 amino acid analog of the human prolactin amino terminus was synthesized, substituting tyrosine for valine at residue 13. The peptide was coupled to crystalline bovine serum albumin for antisera production. The peptide was used for iodination with 125I, and displacement curves were found to be parallel when human prolactin and the synthetic peptide were compared as standards. The radioimmunoassay using the synthetic peptide has the advantages of purity in its roles as hapten in the antigen and as labelled peptide, of ease of iodination of the peptide, of its stability after iodination, and of obviating the need for native human prolactin. The radioimmunoassay is suitable for the measurement of human prolactin concentration in plasma.
Subject(s)
Peptides/chemical synthesis , Prolactin/blood , Amino Acid Sequence , Humans , Peptides/analysis , Prolactin/chemical synthesis , Radioimmunoassay/methodsABSTRACT
We compared the disappearance rate of hGH and hGH20K injected into groups of mice. Radioactivity measurements and RIA were used to determine the amount of hormone in blood collected at various times after injection. The results indicate that the T1/2 value for hGH and hGH20K are equal. We conclude that there is no apparent relationship between the equal rates of disappearance, the dissimilar binding characteristics that have been shown for the hormones and their equipotent growth promoting activities.
Subject(s)
Genetic Variation , Growth Hormone/blood , Animals , Growth Hormone/genetics , Half-Life , Humans , Kinetics , Mice , Molecular Weight , Radioimmunoassay/methodsABSTRACT
Plasma prolactin (hPRL) concentration was measured in four nursing mothers during 24 hour periods. Blood was collected via indwelling catheters and sleep and nursing periods were recorded. Elevated hRPL levels and amenorrhea were seen for as long as 13 months post partum in mothers whose infants nursed frequently. One mother, whose infant nursed less frequently, menstruated and had lower prolactin levels but continued to lactate. Plasma hPRL rose after nursing periods in nine of 18 instances at two months post partum, but in only five of 27 instances at six months post partum. Nighttime release hPRL was higher (five of six) in nursing mothers, just as in normal subjects (five of seven). Therefore it was concluded that prolactin levels in nursing mothers may remain elevated for over one year post partum if frequent nursing continues. Lactation may continue in spite of normal hPRL levels. A consistent rise in hPRL is not seen with nursing episodes occurring after two months post partum. Nursing mothers, like normal women, tend to have higher nighttime release of hPRL.
