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D A Ontjes

Publications and source records attributed to D A Ontjes.

49 records · Page 3Linked to original sources
PubMed1971

Thyrocalcitonin: stimulation of secretion by pentagastrin.

Administration of a small dose of pentagastrin, a synthetic pentapeptide containing the biologically active portion of the native hormone gastrin, results in a marked, rapid, transitory increase in thyrocalcitonin secretion in the pig. Gastrin or a related gastrointestinal peptide may be important in the physiological secretion of thyrocalcitonin, such as that which occurs when calcium salts are introduced into the gastrointestinal tract.

Animals↗
PubMed1969

Solid phase synthesis of a 42-residue fragment of staphylococcal nuclease: properties of a semisynthetic enzyme.

The polypeptide corresponding to the amino acid sequence from residue 6 through 47 in staphylococcal nuclease has been synthesized by the solid-phase method. The synthetic product closely resembles the corresponding native polypeptide in both physical and chemical properties. The synthetic peptide may be recombined with the complimentary native peptide comprising residues 49 through 149 to form an active, semisynthetic enzyme. The "functional purification" of the crude, synthetic polypeptide by affinity chromatography was found to yield a synthetic fraction of greatly enhanced specific activity. This purification was accomplished on a column of Sepharose to which the complimentary native peptide had been covalently bound.

Amino Acid Sequence↗
PubMedDate not supplied

Circulating calcitonin in lactating women.

As part of an initial study we have attempted to ascertain whether lactating women exhibit high, clearly measurable levels of immunoreactive calcitonin (CT). Plasma levels of CT were measured in women who had been lactating for either a short time (less than 4 months) or a very long time (17-73 months). In 2 of 18 women lactating for only a short time CT levels were high and easily measured (greater than 200 pg/ml) while, in contrast, CT levels were undetectable (less than 60 pg/ml) in all of 16 nonlactating control subjects. In all six of the women studied who had been lactating for a long time, measurable levels of CT were observed, although provocative testing of women with measurable plasma CT using iv pentagastrin and calcium did not show a consistent pattern of CT secretory response. Thus, out of the total of 24 lactating women studied, one third were found to have measurable plasma levels of CT. The findings agree with studies in experimental animals which have indicated hypercalcitoninemia during lactation, but the factors responsible for the elevated CT levels during lactation remain to be elucidated.

Calcitonin↗
PubMedDate not supplied

Pituitary tumors.

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Adenoma↗