1993 Volume 40 Issue 2 Pages 245-248
The amounts of immunoreactive proinsulin (IRP), immunoreactive insulin (IRI), and C-peptidelike immunoreactivity (CPR) in six insulinomas and one nesidioblastosis lesion were determined together with those in the surrounding pancreatic tissue. Four non-insulinoma and nondiabetic human pancreases were used as the control. The IRP in the seven tumors ranged from 5.85 μg/g to 65.45μg/g (mean±SEM, 28.70±8.01μg/g), while the IRP in the surrounding pancreatic tissue ranged from 2.08μg/g to 11.71μg/g (5.32±1.76μg/g). Control pancreases had an IRP content of 12.01±2.36μg/g. The IRI in the seven tumors ranged from 4.02U/g to 47.97U/g (14.40±6.35U/g), while that in the surrounding pancreatic tissue ranged from 0.28U/g to 3.64U/g (2.32±0.63U/g). Mean tumor CPR was 206.84±81.6μg/g and it was 29.16±9.15μg/g in the surrounding pancreatic tissue. The molar ratio of the IRP to IRI content was 6.83±1.95% for tumor tissue and 6.24±2.18% for the surrounding pancreatic tissue. These levels were similar to the ratio in the control pancreases (7.67±1.88%), in contrast to the higher serum IRP/IRI ratio in the tumor patients.
