Showing papers by "Rosalyn S. Yalow published in 1989"

Purification of neuropeptides: cholecystokinin and vasoactive intestinal peptide.

Abstract: Publisher Summary With the introduction of new high-performance liquid chromatography (HPLC) separation technologies and automated amino acid sequencing instrumentation, it is now possible to obtain complete sequence analyses of peptides from nanomole or even subnanomole quantities. This new capability for micro-sequencing permits the purification of bioactive peptides to be scaled down to levels that might be termed micro purification. The purification process for Cholecystokinin and vasoactive intestinal peptide follows a series of well-defined steps. The target peptide is extracted from an appropriate tissue source, and the extract is subjected to a purification cycle that consists of a sequence of concentration, separation, and assay steps. Maximum selectivity in the purification cycles is achieved by using different modes of separation when needed and by maintaining a high degree of resolution in each separation. High-resolution separations make it possible to have fewer purification cycles, shorter purification times, and higher yields of pure peptide. As improvements are made in these areas and incorporated into the purification scheme, the purification process will become simpler and the characterization of biologically significant peptides made quicker and easier.

Cholecystokinin and vasoactive intestinal peptide in brain and gut of the hypothyroid neonatal rat.

Abstract: The rat has been a useful model for studying neuronal and metabolic abnormalities associated with fetal and neonatal hypothyroidism produced by treatment of the mother with antithyroid medication. The neonates are then maintained on this medication via the mother's milk until weaning and subsequently through the drinking water. We have determined the concentrations and contents of immunoreactive cholecystokinin (CCK) and vasoactive intestinal peptide (VIP) in the brain and gut of groups of rats exposed to antithyroid medication from day 16 of gestation. The neonates were sacrificed at 2, 4, 8 and 12 weeks. Compared to controls total body weight was greatly reduced in methimazole (MMI)-treated rats, all of whom were hypothyroid as evidenced by marked reduction of T4 and increase in TSH. Discontinuation of MMI-treatment after 8 weeks resulted in normalization of T4 and TSH and a dramatic weight gain but at 12 weeks the brain weights of the MMI-treated rats were reduced by 17% and the brain contents, of CCK and VIP were similarly reduced. Tissue weights throughout the gut were 1/2 or less than those of control rats. Since VIP but not CCK concentrations in the gut of MMI-treated animals were significantly greater than those of the control animals, it would appear that there was greater loss of mucosal tissue with its endocrine content of CCK than of neuronal tissue with its greater content of VIP.(ABSTRACT TRUNCATED AT 250 WORDS)