The peristaltic reflex can be evoked in the absence of input from the CNS because the responsible neural pathways are intrinsic to the intestine. Mucosal enterochromaffin cells have been postulated to be pressure transducers, which... more
The peristaltic reflex can be evoked in the absence of input from the CNS because the responsible neural pathways are intrinsic to the intestine. Mucosal enterochromaffin cells have been postulated to be pressure transducers, which activate the intrinsic sensory neurons that initiate the reflex by secreting 5-HT. All of the criteria necessary to establish 5-HT as this transmitter have been fulfilled previously, except that no mucosal mechanism for 5-HT inactivation was known. In the current investigation, desensitization of 5-HT receptors was demonstrated to inhibit the peristaltic reflex in the guinea pig large intestine in vitro. At low concentration (1.0 nM), the 5-HT uptake inhibitor fluoxetine potentiated the reflex, but higher concentrations blocked it, suggesting that the peristaltic reflex depends on the 5-HT transporter-mediated inactivation of 5-HT. Specific (Na+ -dependent, fluoxetine-sensitive) uptake of 3H-5-HT by intestinal crypt epithelial cells was found by radioauto...
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Good management models and good models for understanding biology differ in basic philosophy. Management models must facilitate management decisions despite large amounts of uncertainty about the managed populations. Such models must be... more
Good management models and good models for understanding biology differ in basic philosophy. Management models must facilitate management decisions despite large amounts of uncertainty about the managed populations. Such models must be based on parameters that can be estimated readily, must explic- itly account for uncertainty, and should be simple to understand and implement. In contrast, biological mod- els are
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Bayesian statistical inference provides an alternate way to analyze data that is likely to be more appropriate to conservation biology problems than traditional statistical methods. I contrast Bayesian tech- niques with traditional... more
Bayesian statistical inference provides an alternate way to analyze data that is likely to be more appropriate to conservation biology problems than traditional statistical methods. I contrast Bayesian tech- niques with traditional hypothesis-testing techniques using examples applicable to conservation. I use a trend analysis of two hypothetical populations to illustrate how easy it is to understand Bayesian results, which are
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Research Interests: Persistent Organic Pollutants, Diet, Environmental Monitoring, Marine And Environmental Pollution, Biological Sciences, and 24 moreAdipose tissue, Feeding Ecology, Environmental Sciences, Fatty acids, Whales, Carbon Isotopes, Stable Isotope, Female, Animals, Male, Polychlorinated Biphenyls, Nitrogen, Feeding Behavior, Nitrogen Isotopes, Continental shelf, CHEMICAL SCIENCES, Gulf of Alaska, Marine Environment, Fatty Acid, Pacific ocean, North Pacific, Orcinus Orca, Predatory Behavior, and Food Chain
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Subsets of myenteric neurons have been identified. To determine the proportional representation of neurons in each, it is necessary to relate the number of neurons in the subset to that of the complete set. Prior estimates of total... more
Subsets of myenteric neurons have been identified. To determine the proportional representation of neurons in each, it is necessary to relate the number of neurons in the subset to that of the complete set. Prior estimates of total numbers of neurons, obtained with many different markers, have varied widely. Markers were compared for counting myenteric neurons in dissected laminar preparations of guinea pig duodenum, jejunum-ileum, and colon; the effect of stretching preparations on these counts was also determined. Markers included the visualization of single-stranded nucleic acid with cuprolinic blue and the immunocytochemical demonstration of neuron specific enolase (NSE), PGP9.5, S-100, and the constitutive expression of a Fos related antigen (FRA). Neurons could not be counted accurately by demonstrating NSE, PGP9.5, or S-100. The number of neurons detected by demonstrating FRA was consistently less than that determined with cuprolinic blue (approximately 65%). Cuprolinic blue-derived estimates of neuron numbers were higher than most reported in the literature, but comparable to those recently obtained with "a nerve cell body" antiserum. Ganglionic area was found to be stretch independent. The rank order of neurons/cm2 and ganglionic area/ unit resting length was colon > duodenum > jejunum-ileum; more neurons were found in the myenteric plexus of the colon (7.3 x 10(6)) than in that of the entire small intestine (6.5 x 10(6)). Prior studies that have obtained denominators for estimating the proportions of myenteric neuronal subsets with markers that do not reveal the entire population should be re-evaluated. The guinea pig colon contains a surprisingly large number of neurons, the physiological significance of which must be determined.