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Biomedical subjects

C M Timson

Publications and source records attributed to C M Timson.

6 recordsLinked to original sources
PubMed1993

Modulation of galanin and neuromedin U-like immunoreactivity in rat corticotropes after alteration of endocrine status.

The localization of galanin in rat lactotropes and human corticotropes is well established. Neuromedin U immunoreactivity is present in rat corticotropes but radioimmunoassay of thyroid-manipulated rat pituitaries has also linked it to the thyroid axis. We found galanin immunoreactivity in some rat corticotropes, so we have re-examined rat anterior pituitary galanin- and neuromedin U-like immunoreactivity by use of immunocytochemistry and electron microscopy in rats in the normal state and after estrogen administration or adrenalectomy. In normal rats galanin immunoreactivity was present in a few corticotropes and lactotropes, females showing more than males; neuromedin U-like immunoreactivity was present in some thyrotropes and most corticotropes, in both sexes. Where galanin, neuromedin U and ACTH immunoreactivities were colocalized in corticotropes they were present in the same granules. Estrogen administration caused an increase in number of galanin immunoreactive lactotropes, as previously shown. The proportion of neuromedin U-positive corticotropes was not affected. After adrenalectomy, only females showed a significant increase in the proportion of galanin-positive corticotropes. Neuromedin U immunoreactivity was significantly increased in both sexes, as previously shown. Thus, in rat, as in man, galanin can be present in corticotropes and its expression appears to be sex-related. This finding, and the demonstration of thyrotrope neuromedin U (only examined in normal females), provide correlation with previous experiments. The influence of endocrine status on the expression of these novel peptides underlines the inherent plasticity of pituitary endocrine cells.

Adrenalectomy↗
PubMed1981

Decrease of pancreatic somatostatin in neonatal nesidioblastosis.

The inappropriate insulin release that is characteristic of severe neonatal hypoglycemia and nesidioblastosis was thought to be principally due to a marked proliferation of B-cells. A possible deficiency of somatostatin, one of the factors controlling insulin release, has only recently been considered. We report have a significant decrease of pancreatic somatostatin cells and somatostatin content in nesidioblastosis, as compared with appropriate controls. Pancreatic tissue from five babies with severe hypoglycemia, hyperinsulinemia, and nesidioblastosis was examined for insulin, somatostatin, and glucagon by immunocytochemistry and radioimmunoassay. There was a variable insulin cell hyperplasia among the nesidioblastotic specimens but no significant difference from controls was detected. In contrast, there was a consistent and highly significant (P less than 0.02) decrease (of more than 50%) of somatostatin cells (controls, 1.29 +/- 0.22%; nesidioblastosis, 0.53 +/- 0.14%, mean +/- SEM). Similarly, there was no significant alteration in insulin content, although a slight increase was found in non-microadenomatous areas of the diseased pancreata (controls, 42.3 +/- 4.1; nesidioblastosis, 58.6 +/- 9.4 nmol/g wet weight of tissue, mean +/- SEM). However, somatostatin content was almost 60% below control values (controls, 0.365 +/- 0.038; nesidioblastosis, 0.16 +/- 0.039 nmol/g), a statistically significant difference (P less than 0.01). Thus, a marked reduction in the content of somatostatin was present in the pancreata of these infants with nesidioblastosis, resulting in a distinct alteration of the normal pancreatic hormone balance.

Fluorescent Antibody Technique↗
PubMed1979

Bombesin-like immunoreactivity in the avian gut and its localisation to a distinct cell type.

The distribution of a bombesin-like immunoreactive peptide in the avian gastro-intestinal tract was analysed by combined radioimmunoassay and immunocytochemistry. Radioimmunoassay of tissue extracts showed that the largest quantities of bombesin-like immunoreactivity were present in the proventriculus (64.5 +/- 6.0 pmol/g) with smaller but still considerable amounts in the gizzard (40.0 +/- 6.0 pmol/g). Immunocytochemically the extractable bombesin-like immunoreactivity was localised in numerous endocrine cells. These, in the proventriculus, were found mainly in the deeper layers of the mucosa. Further study of these cells by the semi-thin/thin technique revealed the presence of characteristic secretory granules. The functional name BN is proposed for this cell type.

Animals↗
PubMed1977

Immunoelectron cytochemical localization of motilin and substance P in rabbit bile duct enterochromaffin (EC) cells.

Using an immunoreactive technique the two peptides, motilin and Substance P, have been localized at the ultrastructural level in enterochromaffin (EC) cells. Motilin occurs in cells containing a mixed population of biconcave and round secretory granules whereas Substance P is found in cells with exclusively round granules. These observations confirm the existence of at least two functionally and morphologically different types of EC cell in rabbit bile duct, both of which contain 5-hydroxytryptamine. Classification of the endocrine cells of the gut on a purely morphological basis is clearly impossible, however.

Animals↗
PubMedDate not supplied

Gastric carcinoids of argyrophil ECL cells.

Histochemical and ultrastructural studies were carried out in four gastric carcinoids, two of which were associated with atrophic gastritis and pernicious anemia. All tumors showed intense argyrophilia and vesicular granules resembling those of endocrine enterochromaffinlike (ECL) cells in normal human gastric mucosa. Tumor cells were found to be unreactive to all the 18 available antiserums to gut hormones, including gastrin, somatostatin, glucagon, and pancreatic polypeptides. The tumors were interpreted as ECL cell argyrophil carcinoids with the various degrees of differentiation and atypia.

Adult↗