Mercury and Radiocesium Accumulation and Associations With Sublethal Endpoints in the Florida Green Watersnake (Nerodia floridana).

Mercury (Hg) and radiocesium (137 Cs) are well-known environmental contaminants with the potential to impact the health of humans and wildlife. Snakes have several characteristics conducive to studying environmental contamination but have rarely been included in the monitoring of polluted sites. We investigated the bioaccumulation of Hg and 137 Cs and associations with sublethal effects (standard metabolic rate [SMR] and hemoparasite infections) in Florida green watersnakes (Nerodia floridana). We captured 78 snakes from three former nuclear cooling reservoirs on the US Department of Energy's Savannah River Site in South Carolina (USA). For captured snakes, we (1) determined whole-body 137 Cs, (2) quantified total Hg (THg) using snake tail clips, (3) conducted hemoparasite counts, and (4) measured the SMR. We used multiple regression models to determine associations among snake body size, capture location, sex, tail THg, whole-body 137 Cs, Hepatozoon spp. prevalence and parasitemia, and SMR. Average whole-body 137 Cs (0.23 ± 0.08 Becquerels [Bq]/g; range: 0.00-1.02 Bq/g) was correlated with snake body size and differed significantly by capture site (Pond B: 0.67 ± 0.05 Bq/g; Par Pond: 0.10 ± 0.02 Bq/g; Pond 2: 0.03 ± 0.02 Bq/g). Tail THg (0.33 ± 0.03 mg/kg dry wt; range: 0.16-2.10 mg/kg) was significantly correlated with snake body size but did not differ by capture site. We found no clear relationship between SMR and contaminant burdens. However, models indicated that the prevalence of Hepatozoon spp. in snakes was inversely related to increasing whole-body 137 Cs burdens. Our results indicate the bioaccumulation of Hg and 137 Cs in N. floridana and further demonstrate the utility of aquatic snakes as bioindicators. Our results also suggest a decrease in Hepatozoon spp. prevalence related to increased burdens of 137 Cs. Although the results are intriguing, further research is needed to understand the dynamics between 137 Cs and Hepatozoon spp. infections in semiaquatic snakes. Environ Toxicol Chem 2022;41:758-770. © 2022 SETAC.

Relationship between acute hypercarbia and hyperkalaemia during surgery.

BACKGROUND: The relationship between hyperkalaemia and metabolic acidosis is well described in the critical care setting; however, the relationship between acute respiratory acidosis and plasma potassium concentration is less well understood. In a controlled model of increasing levels of hypercarbia, we tested the hypothesis of whether increasing levels of hypercarbia are associated with changes in plasma potassium concentrations. AIM: To determine whether increasing levels of hypercarbia are associated with changes in plasma potassium concentrations. METHODS: We performed a post-hoc study examining changes in serum potassium in 24 patients who received increased levels of hypercarbia during cardiac surgery. Arterial blood gases and plasma concentrations of potassium were measured at baseline, 3 min prior to, and then every 3 min for 15 min during the intervention of hypercarbia. The primary endpoint was the absolute change in serum K+ at 15 min compared to the baseline K+ value. The following secondary endpoints were evaluated: (1) The association between CO2 and serum K+ concentration; and (2) The correlation between plasma pH and serum K+ concentrations. RESULTS: During the intervention, PaCO2 increased from 43.6 mmHg (95%CI: 40.1 to 47.1) at pre-intervention to 83.9 mmHg (95%CI: 78.0 to 89.8) at 15 min after intervention; P < 0.0001. The mean (SD) serum potassium increased from 4.16 (0.35) mmol/L at baseline to 4.28 (0.33) mmol/L at 15 min (effect size 0.09 mol/L; P = 0.22). There was no significant correlation between PaCO2 and potassium (Pearson's coefficient 0.06; 95%CI: -0.09 to 0.21) or between pH and potassium (Pearson's coefficient -0.07; 95%CI: -0.22 to 0.09). CONCLUSION: Acute hypercarbia and subsequent respiratory acidaemia were not associated with hyperkalaemia in patients undergoing major surgery.

Vein diameter is a predictive factor for recanalization in treatment with ultrasound-guided foam sclerotherapy.

OBJECTIVE: Ultrasound-guided foam sclerotherapy (UGFS) is a low-cost and minimally invasive treatment option for varicose veins. There is a relative paucity of outcome reports. METHODS: UGFS procedures at a tertiary public hospital between 2010 and 2017 were studied. Either the great saphenous vein (GSV) or small saphenous vein (SSV) was treated. Pretreatment, in-treatment, 6-week, and 1-year post-treatment ultrasound reports were analyzed. The primary outcome was to determine whether vein diameter predicts obliteration failure. RESULTS: There were 457 treatments completed in 290 patients. The GSV was targeted in 372 (81%). Mean vein diameters of the GSV were not different from those of the SSV (GSV, 5.7 mm; SSV, 6.2 mm; P = .18); 109 (24%) had a Clinical, Etiology, Anatomy, and Pathophysiology score of at least 4. Of the 457 UGFS procedures, 360 (78.8%) were for primary veins. Baseline information, including vein diameter, was not different between primary and recurrent veins. At 6 weeks, complete obliteration, partial recanalization, and complete recanalization rates were 54.9%, 29.1%, and 16%, respectively. Of those with complete obliteration at 6 weeks, the recanalization rate at 1 year was 25%. Increasing vein diameter was associated with recanalization at 1 year (obliteration, 4.9 mm; recanalization, 5.7 mm; P = .03), especially for primary veins (4.8 vs 5.8 mm; P = .009). Multivariate analysis showed similar outcome. Vein diameter of >6 mm had good specificity (88%) but poor sensitivity (43%) for predicting obliteration failure. There were 15 (3%) new-onset deep venous thromboses reported on follow-up, all of which were from treatment of primary veins (P = .049). CONCLUSIONS: Only 44% of UGFS procedures were observed to have complete obliteration at 1 year after a single intervention. Significant recanalization developed at 1 year. Increased vein diameter was associated with recanalization. The impact on clinical recurrence is unknown.