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Biomedical subjects

R Keller

Publications and source records attributed to R Keller.

494 records · Page 28Linked to original sources
PubMedDate not supplied

Orcokinin: a novel myotropic peptide from the nervous system of the crayfish, Orconectes limosus.

A myotropic peptide, named orcokinin, was isolated from approximately 1200 abdominal nerve cords of the crayfish, Orconectes limosus. Its amino acid sequence was determined as follows: Asn-Phe-Asp-Glu-Ile-Asp-Arg-Ser-Gly-Phe-Gly-Phe-Asn. This structure was confirmed by synthesis. There is no sequence similarity to any known neuropeptide. Orcokinin exhibits high potency on the crayfish hindgut, enhancing both frequency and amplitude of spontaneous contractions. The threshold of biological activity in vitro was determined to be approximately 5 x 10(-11) M.

Amino Acid Sequence↗
PubMedDate not supplied

High-affinity binding of crustacean hyperglycemic hormone (CHH) to hepatopancreatic plasma membranes of the crab Carcinus maenas and the crayfish Orconectes limosus.

The binding properties of the crustacean hyperglycemic hormone (CHH) of two species, the shore crab, Carcinus maenas (Brachyura) and the crayfish, Orconectes limosus (Astacura), were investigated using purified plasma membranes of one of the main target organs, the hepatopancreas. Assays were performed under equilibrium binding conditions with 125I-CHH as labeled ligand and unlabeled CHH in increasing concentrations as displacing ligand. In both cases, comparable binding characteristics were observed for the homologous CHH to the respective hepatopancreatic membrane source, indicating saturable and displaceable binding with nonlinear dependence on monovalent cations and a dissociation constant (Kd) of 4 to 6 x 10(-10) M. Binding capacity was in the range of 200-400 fmol/mg membrane protein. In heterologous displacement studies a certain degree of species specificity was found, particularly with regard to selective binding by the Orconectes receptor, suggesting that the group specificity of biological activity of CHH reflects coevolution of both hormone and receptor.

Animals↗
PubMedDate not supplied

Evidence for the involvement of the crustacean hyperglycemic hormone in the regulation of lipid metabolism.

Effects of the crustacean hyperglycemic hormone on total lipids in the hemolymph of Chasmagnathus granulata and on free fatty acids, phospholipids, and triglycerides in the hemolymph of Carcinus maenas, as well as on their release by Orconectes limosus hepatopancreas in vitro, were investigated. Eyestalk ablation led to a significant decrease of total lipids in the hemolymph of C. granulata and of free fatty acid levels in C. maenas. Crustacean hyperglycemic hormone injections completely reversed the effects of eyestalk extirpation in short-term experiments. Crustacean hyperglycemic hormone also caused significant elevations of hemolymph phospholipids and triglycerides in eyestalkless C. maenas. The release of free fatty acids and phospholipids from O. limosus hepatopancreas in vitro was significantly increased in the presence of crustacean hyperglycemic hormone. These results suggest a physiological role for crustacean hyperglycemic hormone in the control of lipid metabolism in crustaceans. This role may be similar to that of the adipokinetic hormone of insects.

Analysis of Variance↗
PubMedDate not supplied

Communicating AIDS information to Hispanics: the importance of language and media preference.

Though Hispanics are the fastest-growing minority group in the United States and have a high cumulative incidence of acquired immunodeficiency syndrome (AIDS), very little data are available concerning attitudes and beliefs concerning AIDS in this population. In January 1988, 216 Hispanics from three clinics in Oregon participated in a survey regarding AIDS information acquisition and knowledge. Overall, respondents reported receiving more information about AIDS from broadcast media such as television (42.6%) and radio (19.9%) and less from print media such as newspapers (18.5%) and pamphlets (17.6%). Respondents whose primary language was Spanish tended to have fewer information sources and relied relatively more on broadcast media than on print media. Though over 90% of the sample believed AIDS could be transmitted sexually, only 50% thought condoms could prevent transmission. Compared to primarily English speakers, respondents whose primary language was Spanish were more likely to believe that AIDS could be casually transmitted and less likely to believe that condoms could prevent transmission. This study suggests that more information delivered in an effective manner, both culturally and linguistically, is needed.

Acquired Immunodeficiency Syndrome↗