Showing papers by "Rosalyn S. Yalow published in 1961"

Immunoassay of plasma insulin in man.

Abstract: In recent years, considerable effort has been directed toward the establishment of a sensitive and reliable assay for insulin in body fluids. A detailed review of work in this field is clearly outside the confines of this brief presentation. For present purposes, it is sufficient to note that many of the methods which depend on a biologic response in vitro or in vivo suffer from a lack of sensitivity or specificity and a susceptibility to interfering substances when applied to assay of the very minute concentrations of endogenous insulin in blood. The immunoassay to be described appears to be free of interference from noninsulin substances in blood yet is sufficiently sensitive to require only o.oi ml. plasma, or less, in routine applications. The principle of the immunoassay is based on earlier observations that binding of I -labeled insulin to insulin antibodies is competitively inhibited in the presence of unlabeled insulin.\" Thus, a quantitative relationship could be established between the ratio (B/F) of antibody-bound insulin-I (B) to unbound, \"free,\" insulin (F) and the concentration of unlabeled insulin in solutions prepared from known standards, thereby permitting determination of insulin in unknown samples.\" Although antibody-bound and free insulin may be separated by a number of technics,' we have continued to employ the method of hydrodynamic flow paper strip chromatography, preferred for its precision and economy of effort in the handling of multiple samples and extraordinary sensitivity. Separation of bound and free insulin by this technic depends on the firm adsorption of free insulin to the paper at the site of application (\"origin\") and the migration of antibody-bound insulin away from the origin with the other serum proteins. In the presence of insulin-I, two radioactive peaks are produced, one at the origin representing free insulin, the other with the serum proteins, representing antibody-bound insulin.t

Immunochemical distinction between insulins with identical amino-acid sequences

Abstract: VIRTUALLY all human subjects treated with commercial mixtures of beef-pork insulin develop circulating insulin-binding antibodies that are readily detectable with insulin labelled with iodine-131 by means of paper or starch eleetrophoresis, paper chromatography or ultracentrifugation1. These antibodies react not only with the specific immunizing insulins but also with horse, sheep and human insulins2, and with dog, monkey, rabbit and whale insulins (unpublished work) in greater or lesser degree. Harris, Sanger and Naughton3 have shown that the amino-acid sequences of insulins from four different ungulate species (cattle, pig, horse and sheep) differ only in the 8–10 positions of the A chains. Although some human antisera react quite similarly with these four insulins, certain antisera can distinguish clearly among insulins from the different species, generally reacting much more strongly with beef and sheep insulins than with pork and horse insulins2. These differences in reaction of the ungulate insulins have been related2 to the known differences in the 8–10 sequence of the A-chain or to possible differences in secondary or tertiary structure.

Preparation and purification of human insulin-I-131; binding to human insulin-binding antibodies.

Abstract: The preparation of I131-labeled human insulin from a lot of human insulin containing approximately 25% insulin by weight and its purification from labeled contaminants are described. The reaction of human insulin-I133 with insulinbinding antibodies in the serums of human subjects treated with commercial mixtures of animal insulins is demonstrated directly. Comparison of the binding of human insulin and beef insulin in antiserums from eight insulinresistant and nonresistant diabetic subjects revealed a lesser affinity' of antibody for human than for beef insulin in most cases, but considerable variability in this respect was encountered among different antiserums.

The Effects of X-Irradiation on I 131 -Labeled Iodotyrosines in Solution: The Significance of Reducing and Oxidizing Radicals

Abstract: Effects of x irradiation on I/sup 1//sup 3//sup 1/-labeled L-3- monoiodotyrosine (MIT) and L-3,5 diiodotyrosine (DIT) were studied by using paper chromatography and electrophoresis for identification of the irradiation products Irradiation of MIT in nitrogen results in tyrosine and iodide as the principal products; irradiation in air results in tyrosine, dihydroxyphenylalanine, and iodide Irradiation of DIT in nitrogen results in MIT, hydroxymonoiodotyrosine (presumptive), and iodids In all cases tbe yield is increased in the absence of oxygen Fenton' s reagent does not produce the chemical changes observed after x-irradiation The results suggest that in a nitrogen atmosphere H - radicals are primarily responsible for the alterations, in air both H - and - O/ sub 2/H radicals are responsible, the relative importance of the reduction or oxidation process being determined by the substrate concentration (auth)

Immunoassay of Insulin Content of Crystalline Glucagon Preparations

Abstract: Summary and Conclusions1. The insulin content of each of 2 crystalline glucagon preparations was found to be less than 0.05% by immunochemical assay. 2. Immunologically reactive insulin was not detected in a cysteine treated glucagon preparation.