PubMed Health⌕ Search

Biomedical subjects

M Saffran

Publications and source records attributed to M Saffran.

6 recordsLinked to original sources
PubMed1979

A model for the study of the oral administration of peptide hormones.

The intragastric administration of lysine vasopressin (LVP) to rats is used as a model to study the biological activity of orally administered peptide hormones. Using a modification of the antidiuretic assay of Sawyer, LVP given by stomach tube caused a significant antidiuresis that was dose dependent in doses of 300 to 2000 mU. The simultaneous administration of the protease inhibitor, Trasylol, increased the antidiuretic effect of LVP. The synthetic peptide (1-deamino, 4 valine)-8-D-arginine-vasopressin also caused a dose-dependent prolonged and significant antidiuresis. No pressor effect was observed after intragastric administration of LVP in doses up to 40 U/rat. We are now using this model to test other procedures for enhancing the activity of lysine vasopressin administered in the gastrointestinal tract such as encapsulation into liposomes. The information gained with vasopressin will then be applied to insulin with the ultimate goal of making oral administration practical.

Administration, Oral↗
PubMed1978

Developmental changes in rat adrenocortical cell membrane potential.

Resting membrane potentials of zona fasciculata-reticularis cells of the rat adrenal gland varied with age. The mean membrane potentials of newborn rat adrenal cells was -56.4 +/- 0.7 mV in the first week of life. The mean potential increased slightly to -61.9 +/- 0.8 mV in the second week and then decreased with age to a mean of -38.5 +/- 0.8 mV in 25--50 week old rats and of -25.9 +/- 1.9 mV in 100 week old rats. The changes in membrane potential may correlate with the indices of adrenocortical growth and activity.

Adrenal Cortex↗
PubMed1977

The status of the corticotropin releasing factor (CRF).

Early in the history of studies on the release of ACTH by stress there were indications that ACTH might be released by multiple factors. But the neurohumoral theory, as formulated by G.W. Harris, suggested that every hypophysial hormone had its unique hypothalamic controlling agent and a search for the unique ACTH-releasing hormone went on for about 20 years. This review reexamines the case for multiple releasers of ACTH.

Animals↗
PubMed1975

The ACTH-releasing hormone of the hypothalamus requires a co-factor.

Gel filtration of an extract of rat median eminence tissue in 0.1 N HCl on Sephadex G-25 separated two peaks, both with feeble ACTH-releasing activity. Full activity of the extract was regained when both peaks were recombined. This observation suggests that the ACTH-releasing hormone of the hypothalamus requires a co-factor for activity.

Animals↗
PubMed1975

Transmembrane potentials and steroidogenesis in normal and neoplastic human adrenocortical tissue.

Trans-membrane potentials and steroidogenesis were measured in superfused slices of non-tumor and neoplastic human adrenocortical tissue. Non-tumor tissue was obtained at the time for renal transplant or from tissue removed along with tumors. Non-tumor human adrenocortical tissue had electrophysiological and steroidogenic properties similar to those of the rat and rabbit. In normal medium ACTH stimulated steroidogenesis but had no effect on the membrane potential. In K+-free medium, the cells hyperpolarized, and subsequent addition of ACTH caused depolarization. Trans-membrane potentials of adrenocortical tumors were lower than those of non-tumor cells. Ommission of K+ from the medium caused hyperpolairzation of the tumor cells, but the trans-membrane potentials did not reach the values of hyperpolarized non-tumor cells. ACTH, added to the K+-free medium, caused little or no change in membrane potential of tumor cells except in one case of a virilizing adenoma, which responded very much like non-tumor tissue. Except for the virilizing adenoma, tumor tissue slices produced little or no detectable fluorogenic steroid, even in the presence of large amounts of ACTH or cyclic AMP. The virilizing adenoma responded with increased steroidogensis to ACTH and cyclic AMP.

Adenoma↗