THE EFFECTS OF THE ALKALOID SCOPOLAMINE ON THE PERFORMANCE AND BEHAVIOR OF TWO CATERPILLAR SPECIES.

Plants have evolved many defenses against insect herbivores, including numerous chemicals that can reduce herbivore growth, performance, and fitness. One group of chemicals, the tropane alkaloids, is commonly found in the nightshade family (Solanaceae) and has been thought to reduce performance and fitness in insects. We examined the effects of the tropane alkaloid scopolamine, the alkaloid constituent of Datura wrightii, which is the most frequent host plant for the abundant and widespread insect herbivore Manduca sexta in the southwestern United States. We exposed caterpillars of two different species to scopolamine: M. sexta, which has a shared evolutionary history with Datura and other solanceous plants, and Galleria mellonella, which does not. We showed that the addition of ecologically-realistic levels of scopolamine to both the diet and the hemolymph of these two caterpillar species (M. sexta and G. mellonella) had no effect on the growth of either species. We also showed that M. sexta has no behavioral preference for or against scopolamine incorporated into an artificial diet. These results are contrary to other work showing marked differences in performance for other insect species when exposed to scopolamine, and provide evidence that scopolamine might not provide the broad-spectrum herbivore resistance typically attributed to it. It also helps to clarify the coevolutionary relationship between M. sexta and one of its main host plants, as well as the physiological mechanism of resistance against scopolamine.

Clinical utility of gastric emptying scintigraphy: Patient and physician perspectives.

BACKGROUND: The use of gastric emptying scintigraphy (GES) in the evaluation of patients with dyspeptic symptoms is controversial. Our aim was to investigate objective and subjective parameters of clinical utility of GES from the perspectives of both the patient and the ordering physician. METHODS: Socio-demographic features, healthcare resource utilization, gastroparetic symptoms and quality of life (QoL) were obtained from consecutive patients referred for GES immediately prior to GES and again 4 months later. The ordering physician received a brief survey 2 weeks after the GES regarding their perceptions on whether the test provided them with clinically useful information. KEY RESULTS: One hundred and seventy-two (mean age ± SD 52.0 ± 17.9; 78% female) of 266 patients enrolled completed both the baseline and follow-up questionnaires and comprised our study population. At baseline, patients with abnormal GES had significantly higher gastroparesis symptom scores and reduced QoL. At the 4-month follow-up, an improvement in symptoms and QoL was seen, but the degree of improvement was not significantly different between those with a normal or abnormal GES. One hundred and ninety-seven ordering physicians completed the survey and perceived that GES, particularly when abnormal, provided new information (91%) and resulted in a change in diagnosis (58%) and management (60%). CONCLUSIONS & INFERENCES: Although patients with an abnormal GES generally had worse symptoms and lower QoL, the results of GES did not help to identify those with improved or worsened symptoms or QoL at follow-up. Nevertheless, the ordering physicians generally felt that the results of GES were helpful in managing these patients.

Tail regeneration in Xenopus laevis as a model for understanding tissue repair.

Augmentation of regenerative ability is a powerful strategy being pursued for the biomedical management of traumatic injury, cancer, and degeneration. While considerable attention has been focused on embryonic stem cells, it is clear that much remains to be learned about how somatic cells may be controlled in the adult organism. The tadpole of the frog Xenopus laevis is a powerful model system within which fundamental mechanisms of regeneration are being addressed. The tadpole tail contains spinal cord, muscle, vasculature, and other terminally differentiated cell types and can fully regenerate itself through tissue renewal--a process that is most relevant to mammalian healing. Recent insight into this process has uncovered fascinating molecular details of how a complex appendage senses injury and rapidly repairs the necessary morphology. Here, we review what is known about the chemical and bioelectric signals underlying this process and draw analogies to evolutionarily conserved pathways in other patterning systems. The understanding of this process is not only of fundamental interest for the evolutionary and cell biology of morphogenesis, but will also generate information that is crucial to the development of regenerative therapies for human tissues and organs.