Typhoid fever in Hong Kong junk family

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Studies on experimental insulin immunity. II. The organ distribution of insulin in immune rabbits

The circulating half-life of injected insulin-I-125, and the uptake of this radioactive hormone by various tissues, have been compared in the normal and insulin-immune rabbit. In the normal animal the injected radioactive insulin is carried by albumin or an alpha-globulin, while in the immune animal it is carried in complex with antibody. The circulating half-life appears to have a fast and a slow component. In the normal rabbit the fast component was about 4.8 minutes and the slow component about forty-eight minutes, while in the immune animal the former was ten minutes and the latter about ninety minutes.

In the normal rabbit only about 17 per cent of the injected radioactive insulin remained as TCA-precipitable radioactivity (intact insulin) in blood and tissues one hour after injection, while in the immune animal about 75 per cent remained in this form at the end of one hour. It would appear, however, that some biologic effect was derived from the injection of radioactive insulin into immune animals, since some hypoglycemia occurred.

In both normal and immune animals most of the TCAprecipitable radioactivity one hour after injection of radioactive insulin was retained in serum, muscle, kidney and liver. However, the proportion of intact insulin was seventeen times greater in serum, 50 per cent greater in the heart, about 30 per cent greater in liver and muscle, about 16 per cent greater in lung and about the same in kidney of immune as compared with normal rabbits.

Studies on experimental insulin immunity. I. Dynamics of insulin immunity in the guinea pig

Insulin half life and the formation and characterization of the insulin-binding antibodies have been studied in the guinea pig both in vivo and in vitro. The antigen-antibody complexes have also been studied utilizing cellulose column electrophoresis and Sephadex G-200 column filtration. In addition, a quantitative assay procedure for insulin-binding antibodies has been employed.

In normal guinea pigs the injected insulin-I-125 is carried by at least two serum proteins, presumably albumin and an α. globulin, or more specifically 4.5S and 19S proteins. In immune animals the insulin-antibody complexes are represented by a single peak in the (β-γ globulin region on column electrophoresis; they are distinguishable from the uncomplexed antibodies which are 7S γ1 and 7S γ1 globulins. The precipitating insulin antibody also appears to be a 7S globulin. Moreover, the insulin-antibody complexes occur as a single component in the 19S fraction on Sephadex G-200 filtration, and if the complex were a single molecule it would have a molecular weight equivalent of about 630,000.

During the immunization process the insulin binding antibody titer increases progressively in association with an elevation of 7S globulin. In most animals during the early stages of immunization the molecular weight of the antibodies appears to be exclusively of the 7S globulin type; however, in two of seven animals there was, in addition, a small amount of insulin antibody of 19S globulin type early during the immunization period.

The purpose in estimating a molecular weight equivalent of the insulin-antibody complex relates to the possibility that the distinctive features of the angiopathies of diabetes may depend upon certain physicochemical characteristics of this complex.