H.Gail Pollock

Spectrum effects of a new polypeptide (third hormone?) isolated from the chicken pancreas.

Abstract A broad evaluation was made of the biological effects of a new polypeptide (APP), 36 amino acid residues, MW 4200, isolated from the chicken pancreas. APP is an effective hepatic glycogenolytic and plasma hypoglycerolemic agent in the absence of plasma glucose perturbation. APP (at much lower doses) is also a powerful gastric secretogogue, inducing within seconds marked increases in proventricular volume, H + , pepsin, and total protein release. Such proventricular response is not mediated through systemic cardiovascular alterations or the vagus nerves, and are quite opposite to those observed with beef or chicken glucagon. It is concluded that the chicken pancreas releases APP to exert a “gastrinlike” secretogogic action on the proventriculus and, at higher concentrations, a metabolic action as well.

Isolation and characterization of reptilian insulin: partial amino acid sequence of rattlesnake (Crotalus atrox) insulin.

Insulin was isolated from the pancreas of two species of rattlesnake, Crotalus atrox and C. adamanteus. The procedure involved acid-ethanol extraction, gel filtration and DEAE-Sephadex chromatography. The insulin content of the pancreata was high, approximately 20 mg/100 g pancreas. Both insulins were identical in amino acid composition but this composition differed considerably from that of bovine insulin. Insulin from C. atrox assayed at 21.6 IU/mg in the mouse convulsion assay. The amino acid sequence of C. atrox insulin was determined and found to have some uncommon substitutions in the B chain.

Regional distribution of pancreatic polypeptide and other hormones in chicken pancreas: reciprocal relationship between pancreatic polypeptide and glucagon.

Tissue extracts of discrete lobes of chicken pancreas were assayed for pancreatic polypeptide (PP), glucagon, somatostatin (SRIF), and insulin by radioimmunoassay. Concentrations of all pancreatic hormones except PP were highest in the splenic lobe. PP concentration was greatest in the inferior portions of the three major lobes. There is a reciprocal relationship between PP and glucagon concentration in chicken pancreas. The results with extracts were substantiated by cell frequency measurements using immunocytochemical methods.

Pancreatic polypeptide in islet cell tumors. Morphologic and functional correlations.

Twelve islet cell tumors and one islet cell hyperplasia were studied with immunocytochemical and radioimmunoassay methods. With immunocytochemical staining, all six insulinomas, one mixed insulinoma–glucagonoma, and four gastrinomas were positive for insulin, insulin and glucagon, and gastrin, respectively. Pancreatic polypeptide (PP) was positive in three insulinomas and one mixed insulinoma–glucagonoma. All of the tumors were positive for neuron‐specific enolase (NSE). Radioimmunoassays of tissue extracts further disclosed that all functioning tumors contained more than one pancreatic hormone. PP concentrations of two insulinomas and one mixed insulinoma–glucagonoma were higher than that of normal control pancreases. A study of protein meal‐stimulated PP secretion revealed that three of the insulinoma cases and two gastrinoma cases exhibited higher plasma PP levels than the age‐matched controls. The findings suggest that: (1) both functioning and nonfunctioning islet cell tumors derive from neuroendocrine cells positive for NSE; (2) all functioning islet cell tumors appear to contain PP in the tumor tissue as a minor component; (3) as many as 70% of the patients with islet cell tumors present with abnormally higher plasma PP levels after protein meals; and (4) a study of meal‐stimulated PP secretion may well be used as a marker for the presence of functional islet cell tumors. Cancer 56: 1649‐1657, 1985.

Four pancreatic endocrine cells in the bullfrog (Rana catesbeiana)

Abstract The pancreas of the bullfrog was studied by the immunoperoxidase method and electron microscopy for hormone-storing cells and radioimmunoassay for content of four pancreatic hormones. Immunoperoxidase staining disclosed four cell types, namely insulin, glucagon, somatostatin (SRIF), and pancreatic polypeptide (PP) cells with regional differences of distribution: the hepatic process contained relatively small islets with abundant insulin, glucagon, and PP cells, and a few SRIF cells, whereas the duodenal process contained relatively large islets with abundant insulin cells and scattered glucagon and SRIF cells. There were few PP cells in the duodenal process. The morphology of four distinct secretory granules was confirmed by electron microscopy. The amount of the four hormones was estimated by nonhomologous radioimmunoassay and compared with the levels of immunoreactive hormone measured in human pancreas.

A neuropeptide Y (NPY)-related peptide is present in the river lamprey CNS

Pancreatic polypeptide (PP)-like material from brain+spinal cord, and retina extracts of Lampetra fluviatilis was studied by HPLC and RIA. The brain+spinal cord extract showed a complex elution profile with multiple peaks of immunoreactivity. The retina extract showed a much simpler pattern with a single significant peak along with a trace of a second peak corresponding to the latest and penultimate peaks in the brain extract. Twenty-one out of 36 residues could be sequenced from the latest eluting peak in the brain extract. This sequence showed 81% identity with porcine neuropeptide (NPY) suggesting that both the brain/spinal cord and retina of the river lamprey contain a peptide homologous to NPY.

Structure of a porcine relaxin inactive on the mouse pubic ligament

In addition to B31 (CM-a) and B28 (CM-B) relaxins, acid-acetone extracts of ovaries of pregnant sows contain a third major relaxin species (relaxin C). The major components of relaxin C possess about half the activity of CM-a or CM-B in the guinea pig palpation assay, but are completely inactive in the mouse pubic ligament assay. Its uterotrophic and protein anabolic effects in ovariectomized, estrogen-primed mice, however, are comparable to those of CM-B. Sequence analysis indicates that the two major components of relaxin C, like the other porcine relaxins, consist of two polypeptide chains linked by disulfide bonds. The shorter (A) chains are identical to the A chains of the other porcine relaxins, except for the absence of the N-terminal arginine residue. The B chains display microheterogeneity; the B sequences of the two predominant species are the same as those of the other porcine relaxins through B25, but terminate at valine residue B25 or serine residue B26, respectively.