Genetic differences of combining sites of insulin antibodies and importance of C-terminal portion of the A chain to biological and immunological activity of insulin

Arquilla, Edward R.; Ooms, Henri; Finn, J. Paul

doi:10.1007/bf01106969

Cited by 33 publications

(8 citation statements)

References 12 publications

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“…These differences observed in the reaction with A chain antibodies in the three studies might occur because A chain antibodies obtained from different animals are directed to different regions of A chain; such differences have been reported for insulin antibodies. 18 Immunoassay of A and B chains: Inhibition curves obtained with S-sulfonated A chain and S-sulfonated B chain as shown in figures 1 and 2, respectively, are representative of their respective typical standard curves. Linear relationships are observed over the range of 0.5 to 6 ng.…”

Section: Resultsmentioning

confidence: 99%

Plasma Concentrations of A and B Chains of Insulin in Nondiabetic, Diabetic and High Risk Potential Diabetic Subjects

Varandani

1968

Diabetes

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Radioimmunoassays for the measurement of the A chain and B chain of insulin in the presence of insulin are described. The assays are sensitive to 0.3 ng./ml. each of A chain and B chain. The results of the immunoassays of human plasma indicate that both A and B chains are present in human plasma. The ^T^^q uantitative recovery of added A and B chains from plasma and (b) parallel relationships between the standard curves of A and B chains and results upon dilution of plasma. The mean concentrations of A chain and B chain in plasma from nondiabetic subjects were 3.7 ± 1.0 and^j^^rfc 1.1 ng./ml., respectively. The concentration^of/A chain! W^JTJJm arkedly higher in diab'eti? ana_nigh_2Jjsk_pj)tential diabetic subjects. It appears possible that an elevated level of A "TKaTn may be used as a diagnostic criterion for prediabetes. There was no apparent effect of oral glucose on the concentration of A and B chains in the plasma of nondiabetic subjects as that observed on the concentration of insulin.Studies on the immunospecificity of the cysteine residues of the two chains showed that thiol, S-sulfonated, oxidized and S-carboxymethylated chains reacted similarly; this indicates that S-sulfonated cysteine residues are probably not involved in the antigen-binding reaction. DIABETES 17: 547-56, September, 1968.

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Section: Resultsmentioning

confidence: 99%

Plasma Concentrations of A and B Chains of Insulin in Nondiabetic, Diabetic and High Risk Potential Diabetic Subjects

Varandani

1968

Diabetes

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“…In particular, it is required: (a) that labeled insulin be biologically active; 4(b) that loss of the radioactive iodine label from the insulin molecule not occur except when the insulin molecule is itself degraded; and (c) that the rates of degradation of labeled and unlabeled and of human and beef insulin be similar. Recently, Arquilla, Ooms, and Finn (21) have suggested that a significant portion of insulin 125I, even when only lightly iodinated, is biologically inactive in the rat epididymal fat pad assay. However, there is considerable evidence (22,23) Preserved hormonal function, however, does not rule out the possibility that some more subtle change in the insulin molecule could exist which alters its degradation rate.…”

Section: Discussionmentioning

confidence: 99%

Insulin delivery rate into plasma in normal and diabetic subjects

Stern¹,

Farquhar²,

Silvers³

et al. 1968

J. Clin. Invest.

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A B S T R A C T Removal of insulin-1'3I from plasma was studied in normal and diabetic subjects with both single injection and continuous infusion of isotope techniques. Patients were studied either in the fasting state or during steady-state hyperglycemia produced by a continuous intravenous glucose infusion. Steady-state plasma insulin concentration during these studies ranged from 10 to 264 JuU/ml. Labeled insulin specific activity time curves consisted of more than one exponential, indicating that a multicompartmental system for insulin metabolism exists. A mathematical technique which is applicable to non-first order processes was used to calculate the rate at which insulin was lost irreversibly from the plasma insulin pool. A direct, linear relationship was found between insulin irreversible loss rate and plasma insulin concentration over the range of concentrations studied. This linearity implies lack of saturability of the insulin removal mechanism. Since the plasma insulin pool was in a steady state during these studies, insulin irreversible loss rate was equal to the rate at which newly secreted insulin was being delivered to the general circulation. Therefore, these results indicate that changes in plasma insulin concentration result from parallel INTRODUCTIONDevelopment of a precise immunoassay for the measurement of plasma insulin concentration (1) has greatly facilitated study of carbohydrate and insulin metabolism. Interpretation of plasma insulin measurements has generally rested on the belief that changes in concentration are direct reflections of parallel changes in pancreatic insulin secretion rate. However, there is little experimental evidence in support of this assumption. Because insulin is secreted into the portal vein, and not into the systemic circulation, determination of pancreatic insulin secretion rate in intact subjects presents formidable difficulties. In contrast, plasma insulin removal rate, which in the steady state is equal to the rate of delivery of insulin into the systemic circulation, can be determined by standard isotopic techniques, and many such studies have been published (2-8). Unfortunately these studies suffer from a variety of defects. In some cases (3-7) disappearance of nonspecific proteinprecipitable radioactivity has been followed despite the fact that Berson, Yalow, Bauman, Rothschild, and Newerly (2), and subsequently others (9,10) In three patients (G.B., W.K., and E.D.), continuous infusions of insulin-'I were given by means of a constant infusion pump. In each of these studies, the continuous infusion of isotope was preceded by a primer dose. The infusion rates were: G.B., 170,686 cpm/min; W.K., 135,240 cpm/min; and E.D., 71,439 cpm/min.Primer doses were in each instance equal to 10 times the per minute infusion rate. Venous blood samples were obtained at i hr intervals for 4 hr. Only those samples obtained after isotopic steady state had been achieved were used in the subsequent calculations.Technical procedures. Blood was drawn into tubes containing e...

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“…In order to test these two possibilities, we prepared a specific immune precipitate (Table I) similar to the one used by Hales sulin-125I displaced, plotted against insulin added, resulted in a linear dose-response with a lambda of 0.05 (11). This method and index of precision are similar to that previously reported by Hales and Randle (17).…”

Section: Resultsmentioning

confidence: 84%

“…Antiserum Dilution (Reciprocal) ear vein 1-2 days after the test sample was obtained. We considered adequate antisera which yielded precipitin lines at a dilution of 1/100 utilizing a modification (11) of the micro double diffusion method of Ouchterlony (12). Titration of insulin antisera.…”

Section: Antiseramentioning

confidence: 99%

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Immunological and biological properties of iodoinsulin labeled with one or less atoms of iodine per molecule

Arquilla¹,

Ooms²,

Mercola³

1968

J. Clin. Invest.

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AB S T RAC T Experiments were designed to compare the distribution of free and antibody-bound unlabeled insulin to the distribution of free and antibody-bound insulin-125I. The insulin antibody was incorporated in a specific immune precipitate similar to the one used by Hales and Randle for the radioimmune assay of insulin. Insulin which was not bound by the specific immune precipitate was measured by the immune hemolysis inhibition assay. This report contains evidence that the addition of the unlabeled insulin in the radioimmune assay results in relatively more insulin-125I which remains free and less bound by antibodies than is the case with the unlabeled insulin. Methods are described for the separation of an electrophoretically homogeneous iodoinsulin from samples of crude iodoinsulin with average incorporations of less than 0.2 atoms iodine per molecule. These purified iodoinsulin fractions have a markedly attenuated biological activity. Evidence is presented which supports the postulate that only a portion of the antibodies in guinea pig insulin antiserum are capable of effectively binding with purified iodoinsulin.

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Genetic differences of combining sites of insulin antibodies and importance of C-terminal portion of the A chain to biological and immunological activity of insulin

Cited by 33 publications

References 12 publications

Plasma Concentrations of A and B Chains of Insulin in Nondiabetic, Diabetic and High Risk Potential Diabetic Subjects

Plasma Concentrations of A and B Chains of Insulin in Nondiabetic, Diabetic and High Risk Potential Diabetic Subjects

Insulin delivery rate into plasma in normal and diabetic subjects

Immunological and biological properties of iodoinsulin labeled with one or less atoms of iodine per molecule

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