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C Johnston

Publications and source records attributed to C Johnston.

At least 19 recordsLinked to original sources
PubMed1992

Peptide tyrosine phenylalanine: a novel neuropeptide F-related nonapeptide from the brain of the squid, Loligo vulgaris.

A novel nonapeptide, sequence YAIVARPRFamide, was isolated from brain extracts of the squid, L. vulgaris. Designated peptide tyrosine phenylalanine (PYF), the peptide shows marked homology with the C-terminal nonapeptides of pancreatic polypeptide and neuropeptide F (NPF) from a number of sources. If PYF is the C-terminal nonapeptide of squid NPF, then it may be derived by a novel processing mechanism involving specific cleavage between two TYR residues. PYF may be a highly truncated, receptor-active variant of NPF.

Amino Acid Sequence↗
PubMed1992

Antinuclear and antineutrophil cytoplasmic antibodies (ANCA) in the sera of patients with Felty's syndrome.

The prevalence of antinuclear (ANA) and antineutrophil cytoplasmic antibodies (ANCA) has been studied in the sera of 62 patients with rheumatoid arthritis and 32 patients with Felty's syndrome. The presence of ANA was less in RA than Felty's syndrome (37% versus 69%). Specific autoantibody identification, where possible, was usually of SS-A or SS-B although two sera from patients with Felty's syndrome had low levels of DNA antibody. ANCA was detected in the sera of 33% of patients with Felty's syndrome and was absent in RA sera. The pattern of ANCA staining was either of a diffuse homogenous cytoplasmic or peripheral (pANCA) nature. Classical cytoplasmic granular staining (cANCA) was not identified.

Antibodies↗
PubMed1992

Abdominal pain.

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Abdominal Pain↗
PubMed1992

Evidence for atrial natriuretic peptide-(5-28) production by rat placental cytotrophoblasts.

Atrial natriuretic peptide (ANP), a 28-amino acid peptide, is produced and secreted by cardiac atriocytes to modulate cardiovascular and renal functions. We report here the production of ANP-(5-28) and its 15K mol wt (M(r)) presumptive precursors by cytotrophoblasts of rat placentae. Placental tissues were collected from Sprague-Dawley fetal rats on days 12, 16, 18, and 20 of gestation and acid extracted for immunoreactive (ir) ANP assay. The contents of placental irANP increased over the course of fetal growth, with the highest amount (mean +/- SE, 1083 +/- 125 pg/tissue; n = 7) found near term. Sephadex G-50 gel chromatographic profiles of the placental extract revealed a major peak of irANP coeluted with the 3K M(r) of synthetic rat (r) ANP-(1-28) and a minor peak in the position consistent with that of 15K M(r). HPLC analysis of the 3K M(r) species showed a single peak of immunoreactivity, which eluted with a retention time similar to that of rANP-(5-28). In placental sections, irANP and pro-ANP mRNA were localized by immunoperoxidase staining and colorimetric in situ hybridization in a subpopulation of placental cytotrophoblasts, but not in syncytiotrophoblasts or chorionic cells. Northern blot analysis showed a single band of pro-ANP mRNA in rat placental tissues similar in size to that found in the heart (approximately 0.85 kilobases), with the highest level of pro-ANP mRNA signal detected in the placentae of 16-day gestation fetuses. Our findings suggest that ANP is expressed and produced by a small population of rat placental cytotrophoblasts and that the 15K M(r) precursor peptide is extensively processed into the N-terminal-truncated form of ANP-(5-28) in the tissue.

Animals↗