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Biomedical subjects

L Orci

Publications and source records attributed to L Orci.

At least 343 records · Page 19Linked to original sources
PubMed1980

Transformation of glicentin-containing L-cells into glucagon-containing cells by enzymatic digestion.

Exposure of sections of ileal mucosa to enzymatic digestion with trypsin and carboxypeptidase B reveals a population of immunofluorescent cells after incubation with a specific C-terminally directed antiglucagon serum. These cells, unreactive before enzyme treatment, were identified as L-cells by their immunoreactivity to antiglicentin serum and to cross-reacting (N-terminal) antiglucagon sera. The presence in the L-cells of antigenic sites characteristic of the glucagon-containing cells (A-cells) emphasizes the close relationships between these two cell types, and it further supports the hypothesis of glicentin as a glucagon precursor.

Animals↗
PubMed1980

Effects of intraportal islet transplantation on the transplanted tissue and the recipient pancreas. I. Functional studies.

It is well known that, in diabetes, there is an abnormality of both pancreatic beta and alpha cell secretion. Since islet transplantation can markedly improve the diabetic state in streptozotocin-treated rats, we investigated the effects of intraportal transplantation on the beta and alpha cell secretion of the transplanted tissue. In addition we examined the effects of transplantation on the hormone content of both the transplanted tissue and the endogenous pancreas. Animals were examined 6 and 20 wk after transplantation. Isolated perfusions of the perfusions of the islet-containing livers showed that both glucagon and insulin secretion could be promptly stimulated by arginine. The hormone content of the livers at death revealed that, while the insulin content of transplanted tissue was well maintained, there was a marked reduction in glucagon content. An increase in pancreatic glucagon content was found in rats with untreated diabetes of five months' duration; this was partially or fully prevented by islet transplantation. There was also a moderate increase in insulin content of the pancreases of animals that received islet transplants.

Animals↗
PubMed1980

Elevated portal and peripheral blood concentration of immunoreactive somatostatin in spontaneously diabetic (BBL) Wistar rats: suppression with insulin.

Immunoreactive somatostatin (IRS) was measured in extracted plasma obtained from the hepatic portal vein (PV) and inferior vena cava (IVC) of acute, untreated, spontaneously diabetic Wistar rats (BBL), insulin-treated diabetic rats, and nondiabetic controls. Acetic acid extracts of the pancreas and entire gastrointestinal tract were assayed for IRS, and the volume density of pancreatic D-, A-, and B-cells was determined by quantitative morphometry. The concentration of IRS in the PV and IVC of the untreated diabetic rats was significantly elevated compared with controls, with a much greater percent increase in the IVC compared with the PV. Insulin treatment for 4-6 wk restored the elevated PV and IVC levels to control values. The pancreatic content of IRS and the volume density of D-cells was severely reduced in the diabetic groups whereas gut IRS was unchanged. These data suggest that the elevated blood levels are secondary to insulin deficiency and result from altered peripheral metabolism and/or increased secretion of IRS most probably from the gut. The increased peripheral blood concentration of IRS raises the possibility of an endocrine role of circulating somatostatin in diabetes. The reduction in pancreatic IRS found in this model is probably secondary to insulitis and contrasts with the D-cell augmentation reported in streptozotocin-diabetic rats.

Animals↗
PubMed1980

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.

Amylases↗
PubMed1980

Gap junctions and B-cell function.

The development of gap junctions between pancreatic B-cells was quantitatively assessed in freeze-fracture replicas of isolated rat islets under various conditions of insulin secretion. Stimulation of insulin secretion by glucose in vitro and by glibenclamide in vivo raised the number of gap junctions between B-cells; glibenclamide alone caused an increase in the size of individual gap junctions. In addition, gap junctions of control and stimulated B-cells showed a packing of particles different from that observed under experimental conditions causing functional uncoupling. The results suggest that gap junctions (and probably coupling) are involved in the secretory activity of B-cells.

Animals↗
PubMed1980

Quantitative evaluation of gap junctions during development of the brown adipose tissue.

Gap junctions of rat brown adipose tissue (BAT) were studied with the freeze-fracture technique during development. The frequency and the mean area of gap junctions increased after birth, reached a maximal development during the functional phase of the tissue (birth to 3--4 weeks) and decreased while brown adipose tissue's function regressed (from 3--4 weeks on). Gap junctional area per cell volume, an indirect estimate of intercellular coupling, followed closely the phases of BAT activity, suggesting an involvement of these junctions in the functioning of brown adipose tissue.

Adipose Tissue, Brown↗
PubMed1979

Endocrine pancreas: three-dimensional reconstruction shows two types of islets of langerhans.

Three-dimensional reconstructions of islets of Langerhans, based on immunofluorescent staining of successive serial sections with antiserums to insulin, glucagon, somatostatin, and pancreatic polypeptide reveal a marked difference in the number of cells containing glucagon and pancreatic polypeptide depending on the anatomical location of the islet in the pancreas. The two types of islets are situated in regions of exocrine tissue that are drained by different excretory ducts. This demonstration contradicts the assumption that all islets in the pancreas are similar in their endocrine cell content.

Animals↗
PubMed1979

[Immunocytochemical anatomy of alpha granules in the human endocrine pancreas].

Using the sensitive protein A-gold technique for the demonstration of antigenic sites in thin section for electron microscopy it was found that in the alpha granules of human pancreas, glucagon immunoreactivity (specific, C-terminal) is restricted to the dense granule core while glicentin immunoreactivity predominates on the peripheral halo surrounding the dense core.

Cytoplasmic Granules↗
PubMed1979

Pancreatic fat.

Explore the source record for details and available documents.

Adipose Tissue↗
PubMed1979

Somatostatinoma syndrome. Biochemical, morphologic and clinical features.

Diabetes mellitus, steatorrhea, cholelithiasis and a tumor distorting the duodenum prompted a work-up for somatostatinoma in a 52-year-old man. The responses of pancreatic B-cells but not of A-cells to nutrient stimuli were inhibited, and growth-hormone release was suppressed, suggesting somatostatin resistance in some target tissues. Plasma somatostatin-like immunoreactivity ranged from 9000 to 13,000 pg per milliliter (normal: 88+/-8, mean +/- S.E.M.) and was distributed in four molecular forms, including free somatostatin. The primary tumor contained 5 microgram of somatostatin-like immunoreactivity per milligram of wet tissue, distributed in three of the molecular forms noted in plasma. Plasma calcitonin was also elevated (4650 pg per milliliter; normal: less than 120). Immunocytochemical studies showed that cells of the primary tumor contained somatostatin and calcitonin but no other peptide hormones. Only somatostatin was present in the metastases. Somatostatin was localized electron microscopically in all secretory granules, irrespective of size and shape, whereas calcitonin was present only within a single subpopulation of small granules in the same cells.

C-Peptide↗