Evaluation of a new battery of toxicity tests for boreal forest soils: assessment of the impact of hydrocarbons and salts.

The ability to assess the toxic potential of soil contamination within boreal regions is currently limited to test species representative of arable lands. This study evaluated the use of six boreal plant species (Pinus banksiana, Picea glauca, Picea mariana, Populus tremuloides, Calamagrostis Canadensis, and Solidago canadensis) and four invertebrate species (Dendrodrilus rubidus, Folsomia nivalis, Proisotoma minuta, and Oppia nitens) and compared their performance to a suite of standard agronomic soil test species using site soils impacted by petroleum hydrocarbon (PHC) and salt contamination. To maintain horizon-specific differences, individual soil horizons were collected from impacted sites and relayered within the test vessels. Use of the boreal species was directly applicable to the assessment of the contaminated forest soils and, in the case of the hydrocarbon-impacted soil, demonstrated greater overall sensitivity (25th percentile of estimated species sensitivity distribution [ESSD25] = 5.6% contamination: 10,600 mg/kg fraction 3 [F3; equivalent hydrocarbon range of >C16 to C34] Of/Oh horizon, and 270 mg/kg F3 Ahg horizon) relative to the standard test species (ESSD25 = 23% contamination: 44,000 mg/kg F3 Of/Oh horizon, and 1,100 mg/kg F3 Ahg horizon). For salinity, there was no difference between boreal and standard species with a combined ESSD25 = 2.3%, equating to 0.24 and 0.25 dS/m for the Ah and Ck horizons. The unequal distribution of soil invertebrates within the layered test vessels can confound test results and the interpretation of the toxic potential of a site. The use of test species relevant to boreal eco-zones strengthens the applicability of the data in support of realistic ecological risk assessments applicable to the boreal regions.

Inhibition of translation by cytotrienin A--a member of the ansamycin family.

The ansamycins are a diverse and often physiologically active group of compounds that include geldanamycin and rifamycin, inhibitors of heat shock protein 90 and prokaryotic DNA-dependent RNA synthesis, respectively. Cytotrienin A is an ansamycin-type small molecule with potent antiproliferative and proapoptotic properties. Here, we report that this compound inhibits eukaryotic protein synthesis by targeting translation elongation and interfering with eukaryotic elongation factor 1A function. We also find that cytotrienin A prevents HUVEC tube formation and diminishes microvessel formation in the chorioallantoic membrane assay. These results provide a molecular understanding into cytotrienin A's previously reported properties as an anticancer apoptosis-inducing drug.

Evaluating oral stimulation as a treatment for dysphagia after stroke.

Deglutitive aspiration is common after stroke and can have devastating consequences. While the application of oral sensory stimulation as a treatment for dysphagia remains controversial, data from our laboratory have suggested that it may increase corticobulbar excitability, which in previous work was correlated with swallowing recovery after stroke. Our study assessed the effects of oral stimulation at the faucial pillar on measures of swallowing and aspiration in patients with dysphagic stroke. Swallowing was assessed before and 60 min after 0.2-Hz electrical or sham stimulation in 16 stroke patients (12 male, mean age = 73 +/- 12 years). Swallowing measures included laryngeal closure (initiation and duration) and pharyngeal transit time, taken from digitally acquired videofluoroscopy. Aspiration severity was assessed using a validated penetration-aspiration scale. Preintervention, the initiation of laryngeal closure, was delayed in both groups, occurring 0.66 +/- 0.17 s after the bolus arrived at the hypopharynx. The larynx was closed for 0.79 +/- 0.07 s and pharyngeal transit time was 0.94 +/- 0.06 s. Baseline swallowing measures and aspiration severity were similar between groups (stimulation: 24.9 +/- 3.01; sham: 24.9 +/- 3.3, p = 0.2). Compared with baseline, no change was observed in the speed of laryngeal elevation, pharyngeal transit time, or aspiration severity within subjects or between groups for either active or sham stimulation. Our study found no evidence for functional change in swallow physiology after faucial pillar stimulation in dysphagic stroke. Therefore, with the parameters used in this study, oral stimulation does not offer an effective treatment for poststroke patients.