The Limulus heart consists of a relatively simple neural network, the cardiac ganglion, and its target tissue, cardiac muscle. The large size and exceptional in vitro viability of this system has made it relatively easy to extract, purify, and identify endogenous compounds which alter cardiac function. These agents included peptides, such as protolin and Limulus chromatophorotropic factor, and amines such as dopamine, epinephrine, norepinephrine, octopamine, and serotonin. The accessibility and simple organization of the cardiac ganglion has also permitted clear identification of the sites of action of these amines and peptides. The Limulus heart is thus a very favorable system for studying peptide and amine neurohormones at the network, cellular and molecular levels.

Animals↗

PubMedDate not supplied

Characterization and distribution of FMRFamide immunoreactivity in the rat central nervous system.

FMRFamide immunoreactive material (irFMRFamide) was studied in rat brain and gastrointestinal tract. Highest irFMRFamide concentrations were found in tissues of the gastrointestinal tract and, in the brain, highest concentrations were found in the hippocampus, midbrain, brainstem and hypothalamus. High pressure liquid chromatographic characterization of irFMRFamide demonstrated that the immunoreactive material in brain, pancreas and duodenum was different from molluscan FMRFamide but it was also distinct from any known neuropeptide.

Animals↗

PubMedDate not supplied

Presence and distribution of immunoreactive and bioactive FMRFamide-like peptides in the nervous system of the horseshoe crab, Limulus polyphemus.

FMRFamide immunoreactivity was detected in all regions of the Limulus nervous system, including the brain (6.5 +/- 0.6 pg FMRFamide/mg), cardiac ganglion (2.06 +/- 0.67 pg FMRFamide/mg), and ventral nerve cord (5.8 +/- 0.7 pg FMRFamide/mg). The distribution of immunoreactive FMRFamide (irFMRFamide) was mapped by immunofluorescence and the distribution corresponded to regional RIA data. A good proportion of the CNS and cardiac ganglion neuropile contained irFMRFamide, and fluorescent cell bodies were observed in several areas. High performance liquid chromatography (HPLC) was employed to separate and characterize the FMRFamide-like peptides from extracts of Limulus brains. HPLC fractions were analyzed using coincidental radioimmunoassay and bioassay (the radula protractor muscle of Busycon contrarium). There appear to be at least three FMRFamide-like peptides in the Limulus brain, including one similar to clam FMRFamide. FMRFamide acts on Limulus heart in a biphasic manner at relatively high concentrations (10(-5)M), but has no effect on the activity of the isolated ventral nerve cord. These data suggest that in Limulus FMRFamide-like peptides are acting as neurotransmitters, or neuromodulators.

Animals↗

PubMedDate not supplied

Identification of proctolin in the central nervous system of the horseshoe crab, Limulus polyphemus.

A proctolin-like peptide was isolated from the prosomal CNS of the chelicerate arthropod, Limulus, and purified using size exclusion, ion exchange and high performance liquid chromatography. Coincident bioassay (cockroach hindgut) and radioimmunoassay were employed to identify fractions which contained proctolin-like material. Proctolin-like activity coeluted with synthetic proctolin with all three chromatographic techniques employed. When applied to either the Limulus heart or hindgut preparations, purified Limulus proctolin produced excitatory responses which were indistinguishable from those produced by the synthetic peptide. Purified samples of the Limulus proctolin-like peptide were subjected to Edman degradation and tandem mass spectrometry and the amino acid sequence of the Limulus peptide was determined to be identical to that of cockroach proctolin (H-Arg-Tyr-Leu-Pro-Thr-OH). The presence of proctolin in the Limulus CNS and its biological action on the isolated heart and hindgut suggest a physiological role for this peptide in the regulation of cardiac output and hindgut motility.

Amino Acid Sequence↗

PubMedDate not supplied

Constituents of West African medicinal plants. XXX. Tridictyophylline, a new morphinan alkaloid from Triclisia dictyophylla.

Triclisia dictyophylla Diels (Menispermaceae) is a woody climber indigenous to West Africa which has been used natively as a medicinal in the treatment of several ailments. Chromatography of an extract of the whole plant afforded tridictophylline (3), a new morphinan alkaloid whose structure was established by a consideration of spectral data and confirmed by x-ray crystallographic analysis. The bisbenzylisoquinoline dibenzodioxin alkaloids cocsuline (1) and trigilletimine (2) were also isolated from the same extract.

Africa, Western↗

PubMedDate not supplied

Resistances to naturalistic observation in a geriatric setting.

Two residential floors for the disabled in a Home for the Jewish Aged were the setttings for this research. One stationary camera with an audio-video taping system was used on each floor to collect data on staff-elderly interactions. This procedure permitted systematic comparisons of staff-initiated touching in relation to naturalistic variations in (1) the physical appearances of patients, and (2) the sex, age, and social statuses of interaction partners. This procedure is discussed with regard to the methodological and ethical problems it posed.

Aged↗