Three cobalt-containing macrocyclic compounds previously shown to antagonize cyanide toxicity have been comparatively evaluated for the amelioration of sublethal azide toxicity in juvenile (7−8 weeks) Swiss-Webster mice. The lowest effective doses were determined for hydroxocobalamin, a cobalt porphyrin, and a cobalt-Schiff base macrocycle by giving the antidotes 5 min prior to the toxicant, 27 mg (415 μmol) /kg sodium azide. Both male and female mice were evaluated for their response to the toxicant as well as the antidotes, and no significant differences were noted once weight differences were taken into account. Two of the three compounds significantly decreased the recovery time of azide-intoxicated mice at 10 min after the administration of sodium azide, as determined by a behavioral test (pole climbing). Additionally, azide was determined to cause a several degree drop (∼3 °C) in measured tail temperature, and warming the mice led to a more rapid recovery. The mice were also shown to recover more rapidly when given sodium nitrite, 24 mg (350 μmol)/kg, 5 min after the toxicant; this treatment also suppressed the azide-induced tail temperature decrease. Electron paramagnetic resonance (EPR) measurements of mouse blood treated with sodium azide demonstrated the presence of nitrosylhemoglobin at levels of 10−20 μM which persisted for ∼300 min. The presence of the methemoglobin azide adduct was also detected by EPR at a maximum level of ∼300 μM, but these signals disappeared around 200 min after the administration of azide. The treatment of mice with 15 N sodium azide proved that the nitrosylhemoglobin was a product of the administered azide by the appearance of a two-line hyperfine (due to the 15 N) in the EPR spectrum of mouse blood.■ EXPERIMENTAL SECTION Chemicals. Gases were purchased from Matheson, and all nongaseous reagents (ACS grade or better), including Na 15 N 3 (98%

We compared methods commonly used in the field of river otter (Lontra canadensis) ecology to estimate visitation rates. We evaluated visitation rates estimated from 2 survey protocols based on video detection-individual visitation rate (IVR) and recording visitation rate (RVR)-and one indirect method based on scat detection-scat visitation rate (SVR). From August 2011 through August 2012, overall scat detection and cumulative video data from 403 camera-days in 2 latrine sites (River and Pond, at a study site adjacent to the Salt Fork of the Vermilion River near Fairmount, Illinois, USA) located <50 m apart did not reveal monthly or seasonal differences between SVR and video detection methods. We identified positive correlations among the 3 visitation rates and differences between overall IVR and RVR. All 3 methods resulted in peak visitation rates during winter. However, when these data were stratified by latrine site, we found both positive and negative correlations at the River latrine. Our work supports that SVR, IVR, and RVR are valuable methods to estimate otter visitation rates at latrine sites. However, it is clear that even within such a short distance between these 2 latrines, these methods detected differences in site utilization. The significant positive correlation observed between IVR and RVR (overall and by latrine site) suggests these methods can be used interchangeably. Otter detection using SVR may serve as a complementary assessment tool for IVR and RVR. To optimize cross-study comparisons and interpretation of results, future studies should detail the type of otter detection and visitation rate used, how variables are measured, formulas used in the calculation of the visitation rates, and detailed descriptions of scat counting efforts when using scat as a tool to evaluate otter visitation rates. Ó

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Phosphine (PH3) poisoning continues to be a serious problem worldwide, for which there is no antidote currently available. An invertebrate model for examining potential toxicants and their putative antidotes has been used to determine if a strategy of using Au­(I) complexes as phosphine-scavenging compounds may be antidotally beneficial. When Galleria mellonella larvae (or wax worms) were subjected to phosphine exposures of 4300 (±700) ppm·min over a 20 min time span, they became immobile (paralyzed) for ∼35 min. The administration of Au­(I) complexes auro-sodium bisthiosulfate (AuTS), aurothioglucose (AuTG), and sodium aurothiomalate (AuTM) 5 min prior to phosphine exposure resulted in a drastic reduction in the recovery time (0–4 min). When the putative antidotes were given 10 min after the phosphine exposure, all the antidotes were therapeutic, resulting in mean recovery times of 14, 17, and 19 min for AuTS, AuTG, and AuTM, respectively. Since AuTS proved to be the best therapeutic agent in the G. mellonella model, it was subsequently tested in mice using a behavioral assessment (pole-climbing test). Mice given AuTS (50 mg/kg) 5 min prior to a 3200 (±500) ppm·min phosphine exposure exhibited behavior comparable to mice not exposed to phosphine. However, when mice were given a therapeutic dose of AuTS (50 mg/kg) 1 min after a similar phosphine exposure, only a very modest improvement in performance was observed.