Insulin I-131 Binding in Serum from Normal and Diabetic Subjects by Ultracentrifugation and Gel Filtration

To determine whether antibodies to exogenous insulin hind and inactivate endogenous insulin in vivo, technics were devised to isolate and measure directly antibodyhound endogenous insulin in the presence of residual exogenous hormone in human and rabbit (leporine) serum. Insulin-antibody fractions in serum were isolated by ultracentrifugation or preferential salt precipitation, insulin was extracted by acid alcohol, and exogenous (bovine) and endogenous (human or leporine insulins) were differentially determined by immunoassay.

Section: Measurement and Discrimination Of Circulating Insulin Bound mentioning

confidence: 99%

Section: Measurement and Discrimination Of Circulating Insulin Bound mentioning

confidence: 99%

Production of Autoantibodies to Insulin in Man and Rabbits

Grodsky

1965

“…Recent studies utilizing ultracentrifugation and gel filtration in the study of insulin-I-131 binding in serum from normal and diabetic subjects are also interpreted as showing a lack of evidence for a specific protein carrier of insulin. 84 However, many investigators feel that insulin does circulate in some form or forms of combination with protein, thus perhaps explaining ILA. Utilizing the rat diaphragm assay and electrophoretic fractionation, ILA has been found in the alpha-1 globulins and slowmoving albumins 85 as well as in the alpha-1 globulins (protein-free insulin) and the beta-gamma globulins (protein-bound insulin).…”

Section: Ila: Fractionation Studiesmentioning

confidence: 99%

Insulin-like Activity

Batchelor

1967

This presentation is a review of the ILA concept and considers (1) major insulin assays; description, comparison, and variation of results; (2) location of circulating ILA in the plasma proteins by various technics; (3) types of ILA: "free-bound," "typical-atypical," "suppressiblenonsuppressible," "NSILA," and other forms; (4) inhibitory or antagonistic factors: synalbumin-antagonistic albumin and nonesterified fatty acids; and (5) the ILA concept with respect to vascular membranes and the glucose transport theory. Also included are data comparing insulin levels obtained by the major assays, types of ILA-insulin levels and properties of the various forms of insulin. DIABETES 76: 418-34, June, 1967. During the past ten years much thought and investigative effort have been spent on the concept of insulinlike activity (ILA). Answers to questions pertaining to its origin, chemical composition, and possible physiologic role may well prove important in understanding the diabetic state. The purpose of this discussion will be to consider these questions. Since the concept of ILA is based on the significant differences in circulating insulin levels that result from the three major forms of insulin assay-(i) rat epididymal fat pad, (2) rat diaphragm, and (3) the radioimmunologic assay-it begins with a description of these technics. INSULIN ASSAYS IN VITROThe first type of biologic insulin assay in vitro, utilizing the isolated rat hemidiaphragm, was developed in the early 1950's. It is based on studies showing that small amounts of insulin accelerate both glucose utilization and (perhaps more specifically) glycogen synthesis by the rat diaphragm, 4 " 0 and that a quantitative relationship exists between the concentration of insulin and these effects. 7 ' 8

“…In the absence of antibody, regardless of the serum used, less than 25 per cent of free insulin is removed. 6 After three hours of centrifugation, the Jupper and lower 1 ml. fractions were isolated, insulin was extracted from each fraction with acid alcohol, and total insulin was quantitated by immunoassay with reagent Antiserum No.…”

Section: Insulin-resistant Diabetes With Autoantibodies Induced By Exmentioning

confidence: 99%

Insulin-Resistant Diabetes with Autoantibodies Induced by Exogenous Insulin: Successful Treatment by Insulin Withdrawal

Karam¹,

Grodsky²,

Forsham³

1969

An obese woman was studied over a five-year period, during which time she had three episodes of severe insulinresistant diabetes, associated with a high level of insulin antibodies.During her second hospitalization, there was no evidence of acute stress, suggesting that in addition to obesity, her extremely high levels of antibodies were interfering with the effectiveness of the administered insulin. These antibodies were shown by immunologic methods to bind both circulating exogenous (bovine) and endogenous (human) insulins. With no other specific therapy except the abrupt halt of insulin, her diabetes improved, her antibody liters declined with a half-life of about twenty days, and the capacity of her plasma to bind both exogenous and endogenous insulin decreased. Antibody levels, although much lower, were still detectable more than eighteen months after discontinuing insulin therapy.The patient's marked clinical improvement on stopping insulin, suggested that the high levels of circulating antibodies were a factor in maintaining her severe insulin resistance. Treatment with insulin in this patient was not only ineffective but apparently had worsened her diabetes. The excellent results obtained during her third hospitalization emphasize the superiority of supervised diet and enforced weight reduction over insulin as a choice of treatment in this type of patient. DIABETES J8: 445-54, July, 1969. It has long been known that most obese maturityonset diabetic patients have mild carbohydrate intolerance which is seldom associated with ketosis and does not