The lined sea anemone Edwardsiella lineata has evolved a derived parasitic life history that includes a novel body plan adapted for life inside its ctenophore hosts. Reputedly its sole host is the sea walnut, Mnemiopsis leidyi, a voracious planktivore and a seasonally abundant member of many pelagic ecosystems. However, we have observed substantially higher E. lineata prevalence in a second ctenophore species, the ctenophore predator Beroë ovata. The interplay among these 3 species has important conservation consequences as M. leidyi introductions are thought to be responsible for the severe depletion of numerous commercial fisheries in the Mediterranean basin, and both E. lineata and B. ovata have been proposed as biological controls for invasive M. leidyi. Over a 3-yr period (2004-2006), we collected 8,253 ctenophores from Woods Hole, Massachusetts, including M. leidyi, B. ovata, and a third ctenophore, Pleurobrachia pileus, and we recorded E. lineata infection frequencies, parasite load, and parasite location. We also conducted laboratory experiments to determine the likely mechanisms for parasite introduction and the effect of each host on parasite development. We observed peak E. lineata infection frequencies of 0% in P. pileus, 59% in M. leidyi, and 100% in B. ovata, suggesting that B. ovata could be an important natural host for E. lineata. However, in laboratory experiments, E. lineata larvae proved far more successful at infecting M. leidyi than B. ovata, and E. lineata parasites excised from M. leidyi exhibited greater developmental competence than parasites excised from B. ovata. Although we show that E. lineata is efficiently transferred from M. leidyi to B. ovata when the latter preys upon the former, we conclude that E. lineata larvae are not well adapted for parasitizing the latter species and that the E. lineata parasite is not well adapted for feeding in B. ovata; these developmental and ecological factors underlie the host specificity of this recently evolved parasite.
Purpose: Describe an alternative approach to perform ultrasound-guided injections into the cubital tunnel as a pilot study for cubital tunnel syndrome (CTS) treatment feasibility. Methods: The ulnar nerve was visualized bilaterally on four non-embalmed cadaveric models which were placed in a supine position. To image the cubital tunnel, the subject's elbow was examined in external rotation with the elbow angle at approximately 40° flexion (full elbow extension is considered 0°). The ultrasound transducer was placed transverse to the condylar groove along the medial epicondyle-olecranon axis and the ulnar nerve was identified. Methylene blue 0.35 mL was injected into the ulnar nerve perineural space under ultrasound guidance in a lateral-to-medial approach. Post-injection incisions were made to expose the underlying ulnar nerve and examine the injection sites. Injections were considered accurate if the ulnar nerve perineural space was dyed, and were considered precise if the injection was localized without damaging the ulnar collateral artery. Results: Dissection revealed that the ulnar nerves were covered with dye from the cubital tunnel inlet to outlet. 8-of-8 (100%) injections were accurate; 8-of-8 (100%) injections were precise. Conclusion: This pilot study shows that a lateral-to-medial approach to injecting the cubital tunnel under ultrasound guidance is accurate and precise. The clinical efficacy of such a procedure using corticosteroids should be examined through clinical trials and the results should be compared to other techniques used for treating CTS.
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