Identification of insulin in the human pancreatic juice

In this study, we purified insulin-like substance (ILS) in the human pancreatic juice by the combined use of affinity chromatography and radioimmunoassay (RIA). The amino acid sequence of ILS in the N-terminal region is the same as that of human insulin. The influence of the enzymes present in the pancreatic juice on the RIA procedure, was examined. Trypsin, chymotrypsin and amylase showed steep influences on radioactivity. The addition of enzyme inhibitors could not reduce pseudo-activity, but the elimination of enzymes in the pancreatic juice by ultrafiltration with the Mole-Cut (Millipore, Japan) resulted in a lowering of the pseudo-insulin activity. Affinity chromatography on Sepharose 4B coupled with anti-porcine insulin was used to capture ILS. ILS was eluted by 1 M acetic acid from the affinity column monitoring pH and the insulin activity by RIA. The amino acid sequences of two components of ILS in amino terminal region were Phe-Val and Gly-Ile-Val. This indicates that ILS obtained from human pancreatic juice was the insulin derived from endocrine secretion of pancreas.     

Analysis of pancreatic peptide hormones by reversed-phase high-performance liquid chromatography

Reversed-phase high-performance liquid chromatography (HPLC) is examined as a method for separating pancreatic peptides. The method was based on gradient elution with acetonitrile in an acid phosphate buffer (pH 3.10). Apart from human and porcine insulin all the other peptide standards tested (thyrotropin-releasing factor, vaso-active intestinal polypeptide, human C-peptide, porcine C-peptide, somatostatin, porcine glucagon, porcine proinsulin and porcine pancreatic polypeptide) could be separated simultaneously in 40 minutes with a binary gradient composed of five linear segments and increasing from 0 to 60% acetonitrile. Human and porcine insulin could be almost completely resolved by a minimal reduction in the steepness of the acetonitrile gradient. Repeated injections of human C-peptide and porcine insulin resulted in a coefficient of variation of less than 1.5% in the retention times. The use of 125I-labelled peptides gave recoveries exceeding 90%. HPLC of acid ethanol extracts of autopsy pancreases from three infants showed that the immunoreactivity of the peptides measured remained unaffected by the chromatography. Both immunoreactive C-peptide and immunoreactive insulin (IRI) were recovered in two peaks, the second common peak representing proinsulin and amounting to 6.5 to 8.4% of total IRI. Immunoreactive glucagon was eluted in a single peak. Chromatography of plasma extracts from two infants of diabetic mothers demonstrated that proinsulin accounted for 59-63% of total IRI, while insulin was separated into two peaks corresponding to the standards of human insulin and porcine insulin. These results indicate that reversed -phase HPLC is a method with a good reproducibility and a high recovery applicable to the rapid and effective separation of pancreatic peptides from biological extracts.     

基因工程人胰岛素原和胰岛素的分离纯化及性质研究

E. coli DH 5 alpha cells harboring a plasmid pWR 590-BCA 4 for fused human proinsulin production were cultured. The fused human proinsulin was isolated from the fermented cells and then subjected it to cleavage with BrCN. The cleaved product was then converted to crude proinsulin-S-sulfonate using oxidative sulfitolysis. The isolation of human proinsulin-S-sulfonate was accomplished by ion exchange chromatography on QAE-sephadex A-25, followed by gel filtration on sephadex G-50. The purified human proinsulin-S-sulfonate was folded using a disulfide interchange method. The folding mixture was then chromatographed on sephadex G-50 and purified proinsulin was obtained. The proinsulin was then converted to human insulin and C-peptide by a combination cleavage with trypsin and carboxypeptidase B. The total yield of human insulin was about 5 mg/L The Zinc insulin crystals were obtained with amorphous human insulin using citrate method. The amino acid composition N-terminal sequences as well as C-terminal amino acid residues are in agreement with expected results. The hypoglycemic activity of purified human insulin is 26-27 U/mg, as judged by mouse convulsion assay, and the RIA activity is about 99% of that of porcine insulin.     

The measurement of 11 beta-hydroxy-4-pregnene-3,20-dione (21-deoxycorticosterone) by radioimmunoassay in human plasma

A specific radioimmunoassay (RIA) method is described for the determination of 21-deoxycorticosterone (21 DB) in human plasma. 21-Deoxycorticosterone-3-(O-carboxymethyl) oxime-bovine serum albumin conjugate was used to generate antisera in rabbits. Steroids which reacted significantly with the antisera were found to be progesterone, pregnenolone, corticosterone and 11-oxo progesterone. However, after extraction of plasma and column chromatography on Celite, all these steroids were separated from 21-deoxycorticosterone and consequently did not interfere with the radioimmunoassay. The intra- and interassays coefficients of variation were 8% and 11% respectively. Mean plasma 21-deoxycorticosterone level for healthy subjects was very low: 17.8 +/- 14.8 pmol/l (mean +/- SD) with no statistical difference between males and females. During the ACTH stimulation test, the 21-deoxycorticosterone levels of healthy subjects increased to 84.7 +/- 26.3 pmol/l (mean +/- SD) for males and 79.3 +/- 31.6 pmol/l (mean +/- SD) for females. Consequently high levels of plasma 21-deoxycorticosterone were found in treated patients suffering from congenital adrenal hyperplasia (CAH) with 21-hydroxylase deficiency, particularly in CAH salt-losers with high plasma renin activity (PRA), where the plasma level reached 40,545 pmol/l. Thus, 21-deoxycorticosterone may be a new marker for adrenal 21-hydroxylase deficiency.     

Glucose dependent insulinotropic polypeptide (GIP) infused intravenously is insulinotropic in the fasting state in type 2 (non-insulin dependent) diabetes mellitus

The effects of an intravenous infusion of porcine GIP on beta-cell secretion in patients with untreated type 2 diabetes mellitus have been studied. The subjects were studied on two separate days. After a 10 h overnight fast and a further 120 min basal period they were given an intravenous infusion of porcine GIP (2 pmol.kg-1.min-1) or control solution in random order from 120-140 min. Frequent plasma glucose, insulin, C-peptide and GIP measurements were made throughout and the study was continued until 200 min. Plasma glucose levels were similar throughout both tests. During the GIP infusion there was an early significant rise in insulin concentration from 0.058 +/- 0.006 nmol/l to 0.106 +/- 0.007 nmol/l (P less than 0.01) within 6 min of commencing the GIP infusion and insulin levels reached a peak of 0.131 +/- 0.011 nmol/l at 10 min (P less than 0.01). Insulin levels remained significantly elevated during the rest of the GIP infusion (P less than 0.01-0.001) and returned to basal values 20 min post infusion. No change in basal insulin values was seen during the control infusion. C-peptide levels were similarly raised during the GIP infusion and the increase was significant just 4 min after commencing the GIP infusion (P less than 0.05). GIP levels increased from 16 +/- 3 pmol/l prior to the infusion to a peak of 286 +/- 24 pmol/l 20 min later. At 4 min when a significant beta-cell response was observed GIP levels were well within the physiological range.(ABSTRACT TRUNCATED AT 250 WORDS)     

Presence of galanin in human pancreatic nerves and inhibition of insulin secretion from isolated human islets

Summary In several animal species, galanin occurs in pancreatic nerves and inhibits insulin secretion. However, the presence and action of galanin in the human pancreas have not been established. Therefore, we examined the presence and nature of human pancreatic galanin-like immunoreactive material (GLIR) and the effects of galanin on glucose-stimulated insulin secretion from isolated human islets. Immunofluorescent staining of human pancreas revealed GLIR in fine varicose fibers in both islets and exocrine parenchyma. Furthermore, acid extracts of pancreas (n=3) and isolated islets (n=3) contained 0.17±0.06 and 0.23±0.11 pmol GLIR/mg protein. Human pancreatic GLIR coeluted with synthetic porcine galanin from Sephadex G-50. Moreover, synthetic porcine galanin inhibited glucose-stimulated insulin secretion from collagenase-isolated human islets at dose rates >10^-8 M. Thus, (1) human pancreas is innervated by galanin-containing nerves, (2) human pancreatic GLIR is of similar size as synthetic porcine galanin, and (3) porcine galanin inhibits glucose-stimulated insulin secretion from human islets. Therefore, galanin could be an important local regulator of insulin secretion in man.     

Sensitive and specific two-site immunoradiometric assays for human insulin, proinsulin, 65-66 split and 32-33 split proinsulins.

Monoclonal antibody-based two-site immunoradiometric assays are described for human insulin, proinsulin, 65-66 split and 32-33 split proinsulin. The detection limits of the assays lie in the range 0.8-2.5 pM. The assays for 65-66 and 32-33 split proinsulins do not distinguish between these substances and their respective C-terminal di-desamino derivatives. The assay of 65-66 split proinsulin does not cross-react with insulin, proinsulin or 32-33 split proinsulin. This material was undetectable (less than 1.0 pM) in plasma taken after an overnight fast in eight normal male subjects and the maximum individual concentration reached in plasma taken during an oral glucose tolerance test of these subjects was 3.8 pM. The proinsulin assay cross-reacted 66% with 65-66 split proinsulin but not with insulin or 32-33 split proinsulin. The 32-33 split proinsulin assay cross-reacted 84 and 60% with proinsulin and 65-66 split proinsulin respectively. The insulin assay cross-reacted 5.3, 62 and 5.0% with intact proinsulin, 65-66 split proinsulin and 32-33 split proinsulin respectively. The very low concentration of 65-66 split proinsulin meant that this derivative did not interfere significantly with the specificity of the assays of proinsulin and insulin. The concentration of 32-33 split proinsulin could be calculated by subtracting the cross-reactivity of the measured proinsulin. The mean concentrations of insulin, proinsulin and 32-33 split proinsulin in eight young male subjects in the fasting state were (pM +/- S.E.M.) 20 +/- 0.3, 2.3 +/- 0.3 and 2.1 +/- 0.7 and at the maximum reached during an oral glucose tolerance test, 150 +/- 26, 9.9 +/- 1.4 and 19.7 +/- 6.0 respectively.     

Pharmacological PPARgamma stimulation in contrast to beta cell stimulation results in an improvement in adiponectin and proinsulin intact levels and reduces intima media thickness in patients with type 2 diabetes.

The role of intact proinsulin and adiponectin in endothelial dysfunction and insulin resistance has been receiving increasing attention. This study investigates the effect of PPARgamma stimulation or beta-cell stimulation on metabolic and vascular parameters in patients with type 2 diabetes. In our study, 173 type 2 diabetic patients were recruited and randomly assigned to pioglitazone 45 mg or glimepiride 1 - 6 mg treatment. Intima media thickness of the carotid artery, glycemic control, insulin resistance, adiponectin and intact proinsulin levels were assessed at baseline and after six months of treatment. Despite similar improvements in metabolic control (HbA (1c) after 24 weeks: - 0.8 +/- 0.9% [pioglitazone] vs. - 0.6 +/- 0.8% [glimepiride]; mean +/- SD; p < 0.0001, respectively), improvements in intima media thickness (- 0.033 +/- 0.052 mm; p < 0.0001), proinsulin intact (- 5.92 +/- 10.04 pmol/l; p < 0.0001), adiponectin (10.9 +/- 6.3 microg/ml; p < 0.0001) and HOMA score (- 2.21 +/- 3.40; p < 0.0001) were observed by pioglitazone but not glimepiride treatment. Reduction in intima media thickness was correlated with improved insulin sensitivity (r = 0.29; p = 0.0003), and proinsulin intact levels (r = 0.22; p = 0.006), while an inverse correlation was found with adiponectin levels (r = - 0.37; p < 0.0001). Measurement of adiponectin and intact proinsulin enables characterization of the metabolic situation and an estimation of atherosclerotic risk in patients with type 2 diabetes.     

Isolation and characterization of colipase from porcine and human pancreatic juice by immunoaffinity chromatography

Pure colipase was prepared by immunoaffinity chromatography from porcine and human pancreatic juice. A single form of the porcine colipase was obtained, having the structural and biological properties of previously characterized porcine procolipase A. Two forms of activated colipase (N-terminal Gly) were isolated from human pancreatic juice by the same procedure. The existence of two forms of activated colipase might arise from rapid activation of a precursor form of human colipase during collection of the pancreatic juice.     

Met-Lys-双C肽人胰岛素原基因的构建表达及分离纯化

应用 Ｐ Ｃ Ｒ 定点突变方法构建编码 Ｍ ｅｔ Ｌｙｓ 双 Ｃ 肽人胰岛素原基因,并在大肠杆菌中以包含体方式获得表达 表达产物经还原、重组、 Ｓｅｐｈａｄｅｘ Ｇ ７５ 分离纯化,获得 Ｍ ｅｔ Ｌｙｓ 双 Ｃ 肽人胰岛素原,经胰蛋白酶与羧肽酶 Ｂ的酶解, Ｒｅｓｏｕｒｃｅ Ｔ Ｍ Ｑ 阴离子交换柱层析分离制备得人胰岛素,其放免活性、受体结合活性均与猪胰岛素相同      

Establishment of radioimmunoassay for human islet amyloid polypeptide and its tissue content and plasma concentration

Using a synthetic C- terminal tetradecapeptide of human islet amyloid polypeptide (IAPP), we prepared an antiserum for human IAPP [24-37] and established a highly sensitive radioimmunoassay (RIA) for human IAPP. Analyses of human pancreatic extract using reverse-phase high performance liquid chromatography coupled with the RIA revealed that the antiserum specifically detects human IAPP. The content of IAPP in the pancreas of two non-diabetic patients was 604.0 and 1447.7 pg/mg wet weight, and a small amount of IAPP-immunoreactivity was detected in the stomach, duodenum, and jejunum. The mean plasma concentration of IAPP in 10 normal individuals was 13.5 +/- 4.8 (SD) pg/ml. The RIA established in this study provides a useful tool to elucidate the physiological function of IAPP and its pathophysiological significance in non-insulin-dependent diabetes mellitus (NIDDM).     

Effects of pancreatic polypeptide on the pancreatic exocrine secretion stimulated by secretin and cholecystokinin in the conscious pig

Fourteen castrated male Large White pigs, weighing 42.5 +/- 1.0 kg, were fitted with pancreatic and duodenal fistulae for pancreatic secretion studies. Moreover, catheters were placed in a carotid artery for blood sampling and in a jugular vein for peptide infusion. Pancreatic juice was automatically restituted to the animals and continuously sampled for analysis on experimental days. Following an 8-day recovery period, perfusion studies were performed after an overnight fast. After a 30-min basal period, sustained pancreatic flow and protein output were obtained and maintained throughout the assay with secretin (36 pmol/kg/h) and CCK-8 (600 pmol/kg/h) infusion. Then, 200, 400, 600, 800 or 1200 pmol/kg/h of porcine pancreatic polypeptide (PP) were infused for 60 min. Secretin + CCK infusion was continued for 1 h after PP infusion was stopped. Each dose of PP was given on a separate day. Neither pancreatic flow nor bicarbonate output were affected whatever the dose of infused PP. On the contrary, protein concentration and output decreased with the lowest dose of PP (200 pmol/kg/h) and the diminution was more pronounced with the other doses. With 600 pmol/kg/h as well as with 800 and 1200 pmol/kg/h of PP, pancreatic protein output fell to about 20% of values obtained with secretin + CCK. Plasma levels of PP were below or similar to postprandial values for 200, 400 and 600 pmol/kg/h and they were significantly larger with 800 and 1200 pmol/kg/h. Protein concentration and output returned to values obtained with secretin + CCK infusion after cessation of PP infusion. In conclusion, porcine PP given in physiological doses to the pig decreases pancreatic protein output whereas pancreatic flow remains unaffected.     

Neuropeptide K is present in human cerebrospinal fluid

Neurokinin A-like immunoreactivity (NKA-LI) in human cerebrospinal fluid (CSF) was determined by radioimmuno assay (RIA) combined with high performance liquid chromatography (HPLC). The major immunoreactive component did not coelute with NKA, but coeluted with neuropeptide K (NPK), which contains the NKA sequence in its C-terminus. Trypsin treatment of this component from human CSF and of synthetic NPK, produced a substance which coeluted with NKA in the HPLC system. When the NKA-LI was oxidized with hydrogen peroxide and rechromatographed, the immunoreactivity coeluted with NPK sulfoxide. The results indicate that the main part of the NKA-LI in CSF is identical with NPK. The mean concentration of NPK measured in CSF from 6 healthy subjects by HPLC-RIA was 23 +/- 11 (SD) pmol/L.     

Engraftment of cells from porcine islets of Langerhans following transplantation of pig pancreatic primordia in non-immunosuppressed diabetic rhesus macaques

Transplantation therapy for human diabetes is limited by the toxicity of immunosuppressive drugs. If toxicity can be minimized, there will still be a shortage of human donor organs. Xenotransplantation of porcine islets is a strategy to overcome supply problems. Xenotransplantation in mesentery of pig pancreatic primordia obtained very early during organogenesis [embryonic day 28 (E28)] is a way to obviate the need for immunosuppression in rats or rhesus macaques and to enable engraftment of a cell component originating from porcine islets implanted beneath the renal capsule of rats. Here, we show engraftment in the kidney of insulin and porcine proinsulin mRNA-expressing cells following implantation of porcine islets beneath the renal capsule of diabetic rhesus macaques transplanted previously with E28 pig pancreatic primordia in mesentery. Donor cell engraftment is confirmed using fluorescent in situ hybridization (FISH) for the porcine X chromosome and is supported by glucose-stimulated insulin release in vitro. Cells from islets do not engraft in the kidney without prior transplantation of E28 pig pancreatic primordia in mesentery. This is the first report of engraftment following transplantation of porcine islets in non-immunosuppressed, immune-competent non-human primates. The data are consistent with tolerance to a cell component of porcine islets induced by previous transplantation of E28 pig pancreatic primordia.     

Engraftment of cells from porcine islets of Langerhans following transplantation of pig pancreatic primordia in non-immunosuppressed diabetic rhesus macaques

Transplantation therapy for human diabetes is limited by the toxicity of immunosuppressive drugs. If toxicity can be minimized, there will still be a shortage of human donor organs. Xenotransplantation of porcine islets is a strategy to overcome supply problems. Xenotransplantation in mesentery of pig pancreatic primordia obtained very early during organogenesis [embryonic day 28 (E28)] is a way to obviate the need for immunosuppression in rats or rhesus macaques and to enable engraftment of a cell component originating from porcine islets implanted beneath the renal capsule of rats. Here, we show engraftment in the kidney of insulin and porcine proinsulin mRNA-expressing cells following implantation of porcine islets beneath the renal capsule of diabetic rhesus macaques transplanted previously with E28 pig pancreatic primordia in mesentery. Donor cell engraftment is confirmed using fluorescent in situ hybridization (FISH) for the porcine X chromosome and is supported by glucose-stimulated insulin release in vitro. Cells from islets do not engraft in the kidney without prior transplantation of E28 pig pancreatic primordia in mesentery. This is the first report of engraftment following transplantation of porcine islets in non-immunosuppressed, immune-competent non-human primates. The data are consistent with tolerance to a cell component of porcine islets induced by previous transplantation of E28 pig pancreatic primordia.     

Peptide YY (PYY) immunoreactivity is co-stored with glucagon-related immunoreactants in endocrine cells of the gut and pancreas

In this study we report the localisation of PYY immunoreactivity in intestinal mucosa endocrine (EG) cells containing glucagon-related peptides and also in foetal pancreatic A cells of rat and man. Radioimmunoassay of human foetal pancreatic extracts revealed the presence of PYY immunoreactivity, the concentration of which declined with age (from 65.42 pmol/g at week 20 to 17.0 pmol at week 40; correlation coefficient = -0.893), in contrast to the amount of glucagon which remained statistically constant throughout the same foetal period. The identity of this PYY immunoreactive material with the original 36 amino acid porcine peptide has been shown by high pressure liquid chromatography (HPLC).     

Glucose turnover and hormonal changes during insulin-induced hypoglycemia in trained humans

Eight athletes (T), studied the third morning after the last exercise session, and seven sedentary males (C) (maximal O2 consumption 65 +/- 4 vs. 49 +/- 4 (SE) ml X kg-1 X min-1, for T and C men, respectively) had insulin infused until plasma glucose, at an insulin level of 1,600 pmol X l-1, was 1.9 mmol X l-1. Glucose turnover was determined by primed constant rate infusion of 3-[3H]glucose. Basal C-peptide (0.46 +/- 0.04 vs. 0.73 +/- 0.06 pmol X ml-1) and glucagon (4 +/- 0.4 vs. 10 +/- 2 pmol X l-1) were lower (P less than 0.05) and epinephrine higher (0.30 +/- 0.06 vs. 0.09 +/- 0.03 nmol X l-1) in T than in C subjects. During and after insulin infusion production, disappearance and clearance of glucose changed identically in T and C subjects. However, in spite of identical plasma glucose concentrations, epinephrine (7.88 +/- 0.99 vs. 3.97 +/- 0.40 nmol X l-1), growth hormone (97 +/- 17 vs. 64 +/- 6 mU X l-1), and pancreatic polypeptide (361 +/- 84 vs. 180 +/- 29 pmol X l-1) reached higher levels (P less than 0.05) and glucagon (28 +/- 3 vs. 47 +/- 10 pmol X l-1) lower levels in T than in C subjects. Blood pressures changed earlier in athletes during insulin infusion, and early recovery of heart rate, free fatty acid, and glycerol was faster. Responses of norepinephrine, cortisol, C-peptide, and lactate were similar in the two groups. Training radically changes hormonal responses but not glucose kinetics in insulin hypoglycemia.     

Immunoextracted calcitonin in human gastric secretion

Immunoreactive calcitonin (iCT) has been demonstrated in human gastric juice after immunoextraction with immobilized antibodies and subsequent radioimmunoassay. The basal levels were 4.5 +/- 3.1 (mean +/- SD) pg-Eq/ml gastric juice; range 1.2-9.1 pg-Eq/ml; n = 7, and after stimulatory gastric secretion test with pentagastrin 0.3 +/- 0.2 pg-Eq/ml; range 0.1-0.7 pg-Eq/ml; n = 7 (p less than 0.01). The main fraction of iCT from gastric juice eluted in the same region as synthetic human calcitonin (hCT) on Sephadex G-75 gel chromatography. Reverse phase chromatography in a fast protein liquid chromatography (FPLC) system revealed a slightly less hydrophobic character of the iCT from gastric juice compared to synthetic monomeric hCT. The results were further confirmed by using an additional antiserum. In plasma, the calcitonin (CT) levels were after immunoextraction at the basal state 6.6 +/- 1.7 pg-Eq/ml (mean +/- SD); range 5.1-10.1 pg-Eq/ml; n = 7 and after pentagastrin stimulation 9.4 +/- 5.4 pg-Eq/ml; range 6.3-18.5 pg-Eq/ml; n = 7.     

7B2, a possible marker for nonfunctioning pancreatic islet cell tumor.

Plasma 7B2 was measured in 13 patients with pancreatic islet cell tumors, 11 with pancreatic adenocarcinoma and 31 normal subjects as a control. The mean (+/- SD) concentrations of plasma 7B2 in the normal subjects and the patients with pancreatic islet cell tumors were 67 +/- 10 and 1041 +/- 1786 pmol/l, respectively, and the value in the patients with pancreatic islet cell tumors was significantly higher than that in the normal subjects (p less than 0.01). Elevation of plasma 7B2 over the normal range, defined as less than the mean + 3SD value of those in the normal subjects, was found in 10 of 13 patients with pancreatic islet cell tumors including 4 with nonfunctioning tumor. Plasma 7B2 dropped into the normal range postoperatively in 3 patients with nonfunctioning tumor. Plasma 7B2 concentrations in the patients with pancreatic adenocarcinoma remained in the normal range. These results raise a possibility that 7B2 is a useful marker for pancreatic islet cell tumors, in particular nonfunctioning tumor.     

Determination of insulin-like growth factor-I in normal subjects and in patients with growth hormone disorders by radioimmunoassay using biosynthetic homologous peptide

A highly sensitive and specific RIA for IGF-I has been developed using recombinant DNA-derived IGF-I of very high purity and specific antiserum to it. This assay system could detect IGF-I at as low concentrations as 20-30 ng/ml. The intra-assay and interassay coefficients of variation at various concentrations of IGF-I were 4.9 to 6.5% and 5.4 to 8.0%, respectively. The recovery rate of pure IGF-I added to plasma was 77.0 +/- 3.7%. The antiserum did not cross-react with porcine insulin, biosynthetic human insulin, hGH, hEGF, the synthetic C-domain of IGF-I or that of IGF-II, but reacted equally with an analog, Thr59-IGF-I. Plasma IGF-I was extracted by the acid-ethanol method before assay to separate IGF-I from its binding protein. When plasma IGF-I was assayed without extraction, the inhibition curves of serial dilution of plasma samples from several individuals were not parallel to the standard curve of IGF-I. The plasma concentration of IGF-I was 147 +/- 49 ng/ml (mean +/- SD) in 156 normal adults aged from 20-59 years. As reported by others, the IGF-I levels were low in cord plasma (41.8 +/- 23.5 ng/ml) and plasma of patients with GH deficiency (64.6 +/- 42.0 ng/ml), while its levels were high in normal children of pubertal ages (12-13 yr, 365 +/- 126 ng/ml) and in patients with active acromegaly (562 +/- 115 ng/ml). This RIA system is a simple and useful method for determining plasma IGF-I in normal and diseased states.