Mortality and abnormalities observed after experimental Hg exposure in the polychaete Eurythoe complanata (Pallas) from Mazatlan, Mexico.

Lethal effects of Hg on Eurythoe complanata held under laboratory conditions were evaluated (LC50 and LT50). Worms were exposed to 0-900 microg/L of Hg for 10 days. Mortality occurred in all the treatments, being faster at 200-900 microg/L, which was confirmed by a Friedman ANOVA non-parametric test. The 4-day LC50 = 197.15 microg/L (200 microg/L LT50 = 3.4 days) was similar to that reported for other Hg tolerant annelids. Abnormalities were observed in worms exposed to all the treatments, becoming more severe as Hg concentrations increased: body darkening, rough, white and opaque skin, everted and swollen proboscis and gut evisceration.

B-scan ultrasonography to screen for retinal tears in acute symptomatic age-related posterior vitreous detachment.

OBJECTIVE: To evaluate the performance characteristics of B-scan ultrasonography (US) as a diagnostic test for the detection of retinal tears in acute symptomatic age-related posterior vitreous detachment (PVD). DESIGN: Evaluation of a diagnostic test through a cross-sectional study with prospective data collection. The study intended to meet the 14 items proposed by the Quality Assessment of Diagnostic Accuracy Studies panel. PARTICIPANTS: Two hundred thirty-nine patients with acute-onset age-related PVD were consecutively enrolled in a nonreferral hospital. TESTING: Comprehensive eye examination including vitreous and retinal biomicroscopy was performed on an emergency basis followed by blind B-scan kinetic US. Sensitivity, specificity and predictive values of the index test (B-scan US) were analyzed and compared with the standard reference (baseline examination). In cases of disagreement between both diagnostic methods, a new gold standard was established based on the findings of subsequent directed indirect ophthalmoscopy based on the echographic findings. Positive and negative likelihood ratios and a likelihood nomogram with pretest and posttest odds of retinal tears were calculated for B-scan US. MAIN OUTCOME MEASURES: Index test performance for the detection of retinal tears secondary to age-related PVD. RESULTS: Both diagnostic methods performed comparably. The sensitivity of B-scan US for detection of retinal tears was 96% and that of baseline examination was 89%. Both methods had similar negative predictive values of 99%. B-scan US specificity was 98%. The estimated pretest and posttest probability for a positive B-scan US were 10.8% and 89%, respectively. CONCLUSIONS: Proper B-scan kinetic US is a noninvasive and accurate diagnostic method for the detection of retinal tears that can be reliably used in no view or small pupil cases with symptomatic PVD. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Bioaccumulation and elimination of Hg in the fireworm Eurythoe complanata (Annelida: Polychaeta) from Mazatlan, Mexico.

Mercury accumulation and elimination by Eurythoe complanata were evaluated through two laboratory bioassays in the absence (bioassay A) and presence (bioassay B) of sediment. Ten individuals per treatment (three replicates) were exposed to Hg in solution (0, 1.5, 1.7, 3, 7.4, 8.7, 9, and 11 microg/L) for an 8-day exposure period. At the beginning of the elimination period, the solutions (both bioassays) and sediments (bioassay B) were replaced by seawater only and clean sediment, respectively. This period lasted 8 days. The effect of Hg concentrations on Hg accumulation by worms from bioassay A was confirmed by the Kruskal-Wallis test (H = 19.43, df = 7, chi(2) = 18.475, p = 0.01), whereas this effect was nonsignificant for bioassay B. Specimens from bioassay A accumulated about double the Hg than those of bioassay B. This indicates that sediment plays an important role in the bioaccumulation process. Mercury elimination was observed only on specimens from bioassay B, where 25% to 36% of the total Hg was eliminated during 8 days. This suggests that worms need a longer period of time to completely depurate the accumulated Hg. The Hg balance was performed at the beginning and end of the experimental periods. The total Hg percentage per aquarium decreased at the end of the experiment, which suggests that a considerable amount of Hg was evaporated or adhered to the aquarium walls. This first approach points out that experimental studies using E. complanata as a test species can be useful to evaluate the potential risk produced by Hg or other toxicants on marine biota inhabiting zones subjected to anthropogenic activities.