Amino acid sequence of catfish pancreatic somatostatin I

Two peptides, pancreatic somatostatins I and II, larger and more acidic than synthetic tetradecapeptide somatostatin, have been purified from pancreatic islets of channel catfish (Ictalurus punctata). These peptides have reduced immunoreactivity in a radioimmunoassay for synthetic somatostatin, but full biological activity was measured as inhibition of growth hormone released from isolated rat anterior pituitary cells. Pancreatic somatostatin I is composed of 22 amino acids. Eight additional amino acids are found as an NH2-terminal extension of the segment which is homologous to synthetic tetradecapeptide somatostatin. Seven of fourteen residues of tetradecapeptide somatostatin are present in the COOH-terminal portion of catfish pancreatic somatostatin I. The sequence is NH2-Asp-Asn-Thr-Val-Arg-Ser-Lys-Pro-Leu-Asn-Cys-Met-Asn-Tyr-Phe-Trp-Lys-Ser-Ser-Thr-Ala-Cys-COOH. There is considerable homology with the carboxyl end of synthetic tetradecapeptide somatostatin.

Protein A-gold complex for postembedding staining of intracellular antigens

The use of protein A-gold complex for electron microscopic demonstration of intracellular antigenic sites in thin sections of glutaraldehyde and Epon-embedded tissue is reported. The method is carried out in two steps: thin sections are incubated with specific antisera and the antigen-antibody complexes are then visualized with protein A-gold solution. So far several exocrine pancreatic enzymes as well as polypeptide hormones from the endocrine pancreas have been revealed by this technique.

Transplantation of human fetal pancreas: experience in thymusaplastic mice and rats and in a diabetic patient

The aim of the present study was to investigate if thymusaplastic nude mice and rats are favorable as recipients for transplantation of human fetal pancreas. Twenty human fetal pancreases were transplanted subcutaneously to 20 nude mice, and six human fetal pancreases were transplanted to six rats. The xenografts showed histotypical development of islets of Langerhans. Insulin, glucagon, somatostatin, and pancreatic polypeptide immunoreactivities were also seen in very early stages of the transplant development within the monolayered ducts. With the described "epigastric pouch technique" in rats, we co-ld demonstrate a new in vivo method for selective stimulations and simultaneous blood sampling from tissue-isolated xenografts. Transplantation of human fetal pancreas to the brachioradial muscle of an insulin-dependent patient in combination with a kidney transplant revealed that rejection crises of the kidney led to necrosis of the pancreas transplant, whereas rejection of the kidney was overcome by steroid pulse therapy.

A pancreatic polypeptide (PP)-like immunoreactant is present in the glicentin-containing cell of the cat intestine

BPP-like immunoreactivity was identified in the intestinal mucosa of the cat. In light microscopy BPP immunoreactive cells were found identical to glicentin-containing cells or L-cells. By immunoelectronmicroscopy, BPP-like material was localized within the glicentin-containing secretory granules.

The activation of brain adenylate cyclase and brain cyclic-nucleotide phosphodiesterase by seven calmodulin derivatives

1. A comparison has been made of the ability of seven calmodulin derivatives to displace 125I-labeled calmodulin and to activate adenylate cyclase in a brain particulate fraction. The activation of brain-soluble cyclic-nucleotide phosphodiesterase by the same calmodulin derivatives was examined in parallel. 2. In general, the dose for half-maximal inhibition of 125I-labeled calmodulin binding and the apparent Km of adenylate cyclase activation were comparable in brain membranes. These concentrations were 20--40-times higher than the corresponding apparent Km values of activation of cyclic-nucleotide phosphodiesterase. 3. Modifying the single histidine residue or both tyrosine residues exerted no influence on the biological properties of calmodulin. The carboxymethylation of two methionine residues or the amidation of several carboxyl groups reduced the activation properties of calmodulin on adenylate cyclase and cyclic-nucleotide phosphodiesterase. Altering seven lysine or four arginine residues resulted in two proteins whose activation properties on adenylate cyclase and phosphodiesterase had been modified in a way suggesting that lysine and arginine residues play distinct roles in the interaction of native calmodulin with each enzyme.

[Microcalorimetric study of intact nucleoproteins]

It has been shown that melting of native chromatin complex in tissues and cells is a one stage process with transition parameters Tm = 82 +/- 1 degrees C, delta Tm = 6 degrees C and Qm = (24 +/- 3) cal/g DNA. A conclusion is made that the difference in melting temperatures of chromatin complex and DNA, which is 12 cal/g DNA, corresponds to the melting of secondary and tertiary structures of chromatin. It is shown the destruction of significant part of the secondary and tertiary structures of chromatin by the chromatin complex isolation from tissues and cells.

Post-mortem elemental redistribution in rat studied by x-ray microanalysis and electron microscopy

Post-mortem elemental redistribution in various tissues from rat was studied by means of electron probe X-ray microanalysis, and correlated with morphological changes in these tissues. Pancreas, liver and cardiac muscle were removed from the animal either immediately, or after some hours after death. Elemental distribution at the cellular level was studied by X-ray microanalysis of thick cryosections. Calcium redistribution at the subcellular level was studied using tissue fixed with glutaraldehyde/oxalate. In all tissues, post-mortem redistribution of electrolytes had taken place within 2 h. The cellular concentrations of Na, Cl and Ca increased markedly, those of Mg and K decreased; no significant changes were found in the concentrations of P and S. The number of oxalate precipitates (indicating the presence of calcium) increased both in the mitochondria and in the cytoplasm and endoplasmic reticulum, reaching a maximum at 2 h. Morphological changes included mitochondrial swelling and vesiculation of the endoplasmic reticulum. Since the post-mortem ion shifts are similar to those encountered in some diseases and types of cell injury, great care has to be taken in the interpretation of X-ray microanalytical results from autopsy material.

Immunochemical characterization of neurotensin-like peptides in chicken

Using radioimmunoassay and 3 region specific antisera toward bovine neurotensin (NT), the NT-like peptides in chicken have been shown to differ from NT but to strongly resemble its COOH-terminal region. Three substances were identified, one of which resembled NT biologically and appeared to share 7 or 8 of its COOH-terminal residues. The two other peptides were smaller than NT but seemed to possess 4-6 residue homologies with it. Tissue distribution studies indicated that the chicken pancreas and thymus had unusually high levels of this material (greater than 200 fold than in rat) and that the 3 substances were distributed differently in tissues. Chromatographic studies showed that the peptides obtained form brain, intestine, thymus, and pancreas were similar. These results, demonstrating evolutionary conservation of the COOH-terminal region of NT, are in keeping with the known importance of this region for biological activity. These finding also suggest the exstence of an NT-family of peptides serving multiple biological roles.

Immunofluorescent localization of gamma-glutamyl transferase in rat and bovine tissues

A distribution of the enzyme in tissue sections was studied by direct fluorescent technique using immunoglobulins from rabbits immunized with the rat and bovine kidney enzyme. For studies rat and bovine sections of kidneys, livers, pancreas, and small intestine were used. Cell distribution of the enzyme by immunofluorescent method was the same as that by the classical histochemical method. No differences in the enzyme distribution were noted when either immunoglobulins anti-heavy form or immunoglobulins anti light form of the enzyme were used. Bovine kidney enzyme coupled to diazotized p-aminobenzoyl-hexamethylenediamine-sepharose is a effective sorbant for affinity chromatography of antibody. Precipitates formed between antibodies and purified rat or bovine gamma-glutamyl transferases preserves over 60% of the initial enzyme activity.

The location of VIP in the pancreas of man and rat

VIP has powerful stimulatory effects on both endocrine and exocrine pancreas but its localisation within the gland has not been established. In this study, human pancreas was obtained fresh at surgery (eleven) or within four hours of death (seven). The pancreas was also removed from rats (twenty-two). Immunocytochemical staining showed VIP to be present in fine nerve fibres in all areas of the pancreas. Many fibres were seen in the exocrine pancreas, running between the acini, and around ducts and blood vessels. In addition, dense networks of fibres were observed forming meshes around islets and occasional ganglia were found containing immunoreactive cell bodies. In general, there were fewer VIP fibres in the rat pancreas than in the human, but overall distribution was identical. The mean VIP content of whole human pancreatic tissue was 42 +/- 10 pmol/g wet weight (38 +/- 9 pmol/g in head, 49 +/- 6 pmol/g in body and 42 +/- 11 pmol/g in tail). Whole rat pancreatic tissue contained 28 +/- 7 pmol/g wet weight while preparations of isolated islets were found to contain 374 +/- 30 pmol/g. It is possible that the heavy VIP innervation of the islets described here indicates a role in the regulation of islet hormone release.

Luteinizing hormone-releasing factor-like immunoreactivity in islet cells and insulomas of the human pancreas

Luteinizing hormone-releasing factor (LRF)-like immunoreactivity was demonstrated by a three-layer immunoperoxidase method in the islet cells of human pancreas and in the neoplastic cells of insulomas. Adenocarcinomas originating in the exocrine pancreas were LRF-negative. The results demonstrate another hypothalamic peptide-like material in the gastrointestinal tract, the biological role of which remains to be clarified.

An X-ray microanalysis survey of the concentration of elements in the cytoplasm of different mammalian cell types

Electron probe energy dispersive X-ray microanalysis was performed on freeze-dried tissue sections. The dry weight concentration of elements (mmole/kg dry weight) was measured in the cytoplasm of several cell types from adult mice and rats. This comparative investigation showed: (1) That the energy dispersive X-ray spectrum of element concentration from the cytoplasm of a specific cell type allows one to distinguish this specific cell type from other cell types with considerable accuracy. (2) That there is a relationship between the concentration of the various elements and the ultrastructural features of the cytoplasmic regions being analyzed. For example, areas rich in ribosomes are also rich in P, K and Mg. (3) These data support the idea that K is directly involved in the control of protein synthesis. The catalog of element concentrations in the cytoplasm of 13 cell types from both mice and rats should be of value to others who seek to answer various questions about these cell types.

Amines and the rat exocrine pancreas: (2) Effects of receptor blockers on turnover of L-5HTP

The metabolism of L-5HTP by the rat exocrine pancreas, and effects of blockers on the metabolism were studied by fluorescent histochemical and chemical methods. Histochemically, 5-hydroxytryptamine (5-HT) blockers (methyserigide and cyprohepatdine) and dopamine (DA) blockers (haloperidol and sulpiride) produced no apparent changes in fluorescence pictures after injection of L-5HTP. alpha-blockers (phenoxybenzamine and phentolamine) and monoamine oxidase (MAO) inhibitor (iproniazide) produced an increased accumulation of 5-HT fluorescence in the apical regions of acinar cells where the zymogen granules are stored. Chemically, the 5-HT blockers decreased the 5-HT content after injection of L-5HPT. Sulpiride had no effect. Haloperidol decreased the 5-HT content. MAO inhibitor resulted in a vast accumulation of L-dopa: e.g. (1) L-5HTP was more slowly eliminated, and (2) 5-HT blockers produced a decreased content of 5-HT after injection of L-5HTP, in contrast to the finding that DA-blockers produced an incresed content of DA after injection of L-dopa. The mechanism responsible for the differences is discussed in relation to the possible pharmacological effects of L-5HTP and L-dopa on the secretion from the exocrine pancreas of rats.

Amines and the rat exocrine pancreas: (1). Effects of receptor blockers on turnover of L-dopa

The acinar cells of the exocrine pancreas have the capacity of efficiently take up and metabolize L-dopa. In the present study, the metabolism of L-dopa by the exocrine pancreas of the rat and effects of receptor blockers on the metabolism were studied by fluorescent histochemical and chemical methods. After i.v. administration of L-dopa (50 mg/kg), a large amount of dopamine (DA) was detected in the exocrine pancreas, and in the pancreatic juice large amounts of DA and its metabolites. DA-blockers (haloperidol, sulpiride, and pimozide) and alpha-blockers (phenoxybenzamine, and phentolamine) produced a significant increase in the accumulation of DA after administration of L-dopa. On the other hand, beta-blockers (propranolol, and oxprenolol) were without effects. The excretion of DA into the pancreatic juice appeared to be associated with the secretion of zymogen granules, thus DA serves as an indicator of pancreatic secretory activity, especially of enzyme secretion. Because DA- and alpha-blockers produced an increase in the accumulation of DA, dopaminergic and/or alpha-adrenergic mechanisms probably exist in the exocrine pancreas of the rat and these mechanisms modify the enzyme secretion.

Phylogenetic and anatomical distribution of somatostatin in vertebrates

Immunoreactive GH release-inhibiting factor [somatostatin (SRIF)] was detected in hypothalamus, extrahypothalamic brain, pancreas, and stomach extracts of the rat, pigeon, tortoise, frog, teleost (cichlid), and elasmobranch (dogfish) and in the whole brain of the cyclostome (hagfish). The SRIF concentration was higher in the pancreas and gastrointestinal tract than in the hypothalamus and extrahypothalamic brain in most species. Extracts of the various tissues from the different species assayed in serial dilutions gave displacement curves parallel to those of synthetic mammalian SRIF. Cation exchange chromatography of hypothalamic extracts from the various species revealed two major immunoreactive peaks, one of which correpsonds to synthetic SRIF in elution volume, the other being less basic. Affinity chromatography-purified immunoreactive SRIF from frog brain, pancreas, and stomach extracts coeluted with synthetic SRIF in high pressure liquid chromatography. The results indicate that immunoreactive SRIF in various tissues and in different vertebrates is indistinguishable and suggest that there has been no change in the molecule during at least 400 million yr of evolution.

Identification of a lobe in the adult human pancreas rich in pancreatic polypeptide

Systematic sampling of human necropsy pancreases has revealed that pancreatic polypeptide (PP) cells are not distributed equally in the gland. PP-cells are the most abundant cell type in the posterior part of the pancreatic head while they are scarce or absent in the remainder of the gland. The PP-rich part of the head can be separated by blunt dissection from the pancreas as a discrete lobe. This lobe probably originates from the ventral pancreatic bud during embryogenesis. A quantitative study of the immunofluorescent endocrine cell types (insulin, glucagon, somatostatin and pancreatic polypeptide cells) in PP-rich and PP-poor regions of pancreases in 8 subjects with ages ranging from 33 fetal weeks to 80 years, showed that the proportions of the cell types were different in youngs and adults.