Showing papers by "University of the Philippines Manila published in 1987"
TL;DR: It is demonstrated that a combination of two omega-conotoxins can be used for biochemically defining receptor subtypes and suggested that these correspond to subtypes of neuronal Ca2+ channels.
Abstract: The omega-conotoxins from the venom of fish-hunting cone snails are probably the most useful of presently available ligands for neuronal Ca channels from vertebrates. Two of these peptide toxins, omega-conotoxins MVIIA and MVIIB from the venom of Conus magus, were purified. The amino acid sequences show significant differences from omega-conotoxins from Conus geographus. Total synthesis of omega-conotoxin MVIIA was achieved, and biologically active radiolabeled toxin was produced by iodination. Although omega-conotoxins from C. geographus (GVIA) and C. magus (MVIIA) appear to compete for the same sites in mammalian brain, in amphibian brain the high-affinity binding of omega-conotoxin MVIIA has narrower specificity. In this system, it is demonstrated that a combination of two omega-conotoxins can be used for biochemically defining receptor subtypes and suggested that these correspond to subtypes of neuronal Ca2+ channels.
336 citations
TL;DR: The characterization of a biologically active, homogeneous 125I-labeled monoiodinated Tyr22 derivative of omega-conotoxin GVIA and its use in binding and cross-linking studies are described and four types of Ca channels in chick tissues are defined, consistent with the hypothesis that the alpha-subunits of certain neuronal Ca2+ channels (Ln, N) are the molecular targets of omega.
Abstract: omega-Conotoxin GVIA (omega-CgTx-VIA) is a 27 amino acid peptide from the venom of the fish-hunting snail, Conus geographus, that blocks voltage-activated Ca channels. The characterization of a biologically active, homogeneous 125I-labeled monoiodinated Tyr22 derivative of omega-conotoxin GVIA and its use in binding and cross-linking studies are described. The 125I-labeled toxin is specifically cross-linked to a receptor protein with an apparent Mr of 135,000. The stoichiometry between omega-conotoxin and nitrendipine binding sites in different chick tissues was determined. Skeletal muscle has a high concentration of [3H]nitrendipine binding sites (greater than 1000 fmol/mg) but no detectable omega-conotoxin sites (less than 7 fmol/mg). Brain microsomes have both binding sites, but omega-conotoxin targets are in excess. These results, combined with recent electrophysiological studies (E. W. McCleskey, A. P. Fox, D. Feldman, L. J. Cruz, B. M. Olivera, R. W. Tsien, and D. Yoshikami, unpublished results), define four types of Ca channels in chick tissues, N, T, Ln (omega sensitive), and Lm (omega insensitive), and are consistent with the hypothesis that the alpha-subunits of certain neuronal Ca2+ channels (Ln, N) are the molecular targets of omega-conotoxin GVIA.
147 citations
TL;DR: There is a high degree of consistency between the reasons given by individual women for discontinuing the contraceptive method and their vaginal bleeding pattern during the 90 days preceding discontinuations, however the data revealed large between-centre differences, both in the incidence of specific patterns, and in the identification by women of bleeding problems as reasons for discontinuation.
35 citations
TL;DR: Three women who had been tortured and sexually abused during imprisonment as political prisoners during the dictatorship in the Philippines were treated with a nonverbal, manual stress-tension reduction therapy (STRT), and it is suggested that STRT may be use in other sexological disorders.
Abstract: Three women who had been tortured and sexually abused during imprisonment as political prisoners during the dictatorship in the Philippines were treated with a nonverbal, manual stress-tension reduction therapy (STRT). All women had difficulty in sexual and social relationships and a series of unspecific complaints such as headache, dizziness, irritability, aggressiveness toward their own children, etc. The therapy is described. A series of four sessions was given each woman, followed by group training. A remarkable improvement was noted, and it is suggested that STRT may be of use in other sexological disorders.
11 citations