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Serum proinsulin

The measurement of C-peptide provides a fully validated means of quantifying endogenous insulin secretion, preventing influence of exogenous insulin or insulin antibody. However, most C-peptide assay kits cannot differentiate C-peptide from proinsulin and proinsulin conversion products. The influence of proinsulin may be significant in cases where serum proinsulin is elevated, as in Type 2 diabetes, familial hyperproinsulinemia and in patients with proinsulin antibody. [Pg.467]

IGF-I and II have a proinsulin-like primary structure. Their major site of production is the liver, from which they are secreted continuously rather than being stored. Thus serum serves as their reservoir where they are bound non-covalently to specific carrier proteins [48]. [Pg.329]

Indirect Two-Site Immunoradiometric Assay of Human Proinsulin. The method used is that described by Rainbow et al. Plastic tubes coated with purified guinea pig anti-insulin antibodies are prepared as described above 200-jul samples containing human proinsulin are added to these coated tubes and incubated at 4° for 24 hr. After removal of the sample, tubes are washed twice with 400 /tl of NIGP buffer. Rabbit antibody to human C-peptide is diluted to 1/1000 in 50 mM sodium phosphate buffer, pH 7.4, containing 150 mM sodium chloride, 10 g of bovine serum albumin per liter, and 100 mg of guinea pig IgG per liter 200 /til are added to each tube. After a further 24 hr of incubation at 4 the tubes are washed twice as previously and 200 /u,l of I-labeled sheep anti-rabbit IgG (10,000 cpm) are added in the same buffer as that used for diluting the C-peptide antiserum. After a final 24 hr of incubation and two further washes as above, the tubes are counted. [Pg.353]

A stable isotope dilution assay using mass spectrometry to measure insulin, proinsulin, and C-peptide has been developed. The difference in mass among the three analytes allows specific measurement of each protein. Comparison of patient samples revealed that most, but not all, results were higher by immunoassay than mass spectrometry. Thus immunoassays may overestimate insulin, particularly at low concentrations. The high protein concentration in the serum requires extraction of proteins (e.g., by immunoaffinity) and purification by high-performance liquid chromatography (HPLC) before quantification by mass spectrometry. This method is not suitable for routine laboratory analysis. [Pg.852]

Dhahir FJ, Cook DB, Self CH. Amplified enzyme-linked immunoassay of human proinsulin in serum (detection limit O.lpmol/L). Clin Chem 1992 38 227-32. [Pg.894]

Melani F, Rubenstein AH, Oyer PE, Steiner DF. Identification of proinsulin and C-peptide in human serum by a specific immunoassay. Proc Nat Acad Sci USA 1970 67 148-55. [Pg.470]

Chlorogen Plastid accumulation of vaccines, proinsulin, antibodies, human serum albumin 111-114... [Pg.839]

Insulin in the body is derived from its precursor molecule proinsulin. During the conversion of proinsulin to insulin, a small peptide (C-peptide) is released by enzymic action. Measurement of this peptide in serum provides a measure of pancreatic -cell function, even in patients on insulin. C-pep-tide determination can be used in the evaluation of a number of metabolic conditions, e.g. brittle diabetes, insulinoma. [Pg.101]


See other pages where Serum proinsulin is mentioned: [Pg.57]    [Pg.449]    [Pg.132]    [Pg.3236]    [Pg.857]    [Pg.104]    [Pg.249]    [Pg.214]    [Pg.223]    [Pg.534]    [Pg.539]    [Pg.183]    [Pg.223]   


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Proinsulin

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