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In this assay for immunoreactive human proinsulin (IRPI), it first is separated from plasma by use of an antiserum to human C-peptide. An immunoprecipitate is then formed by using a precipitating antiserum and polyethylene glycol, after which IRPI is dissociated from the antiserum by incubation in warm HCl, pH 2.0. The resulting mixture is assayed for insulin immunoreactivity by a double-antibody tracer-competition method involving incubation for four days with a high-affinity anti-insulin antiserum. Human proinsulin of recombinant-DNA origin is used as the standard. Added C-peptide at supraphysiological concentrations did not interfere with or react in the assay. Human insulin cross reacted by 1.5%. The detection limit for IRPI (2 SD from zero-dose binding) is 3 pmol/L. Proinsulin conversion intermediates are measured nearly as well as intact proinsulin. IRPI concentrations in 10 nondiabetic human subjects averaged 12.0 (SEM 1.6) pmol/L. The ratio of proinsulin to immunoreactive insulin averaged 14.3 (SEM 2.2)%. After intravenous arginine, the increase in proinsulin was less than that of insulin, and it declined more slowly.
W K Ward, and
T L Paquette, and
B H Frank, and
D Porte
February 1977,
Radioisotopes,
W K Ward, and
T L Paquette, and
B H Frank, and
D Porte
June 1976,
Hoppe-Seyler's Zeitschrift fur physiologische Chemie,
W K Ward, and
T L Paquette, and
B H Frank, and
D Porte
April 1974,
Endocrinologia japonica,
W K Ward, and
T L Paquette, and
B H Frank, and
D Porte
April 1973,
Endocrinologia japonica,
W K Ward, and
T L Paquette, and
B H Frank, and
D Porte
January 1971,
Hormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et metabolisme,
W K Ward, and
T L Paquette, and
B H Frank, and
D Porte
January 1990,
Biomedica biochimica acta,
W K Ward, and
T L Paquette, and
B H Frank, and
D Porte
January 1977,
Radioisotopes,
W K Ward, and
T L Paquette, and
B H Frank, and
D Porte
July 1988,
Journal of biological standardization,
W K Ward, and
T L Paquette, and
B H Frank, and
D Porte
September 1999,
Annals of clinical biochemistry,
W K Ward, and
T L Paquette, and
B H Frank, and
D Porte
November 1975,
Rinsho byori. The Japanese journal of clinical pathology,
