Outcomes associated with apixaban vs warfarin in patients with renal dysfunction.

Apixaban in patients with impaired renal function is supported by limited data. Landmark clinical trials evaluating apixaban in patients with atrial fibrillation and/or acute venous thromboembolism excluded patients with creatinine clearance (CrCl) <25 mL/min. This multicenter, retrospective chart review was conducted to evaluate the safety and effectiveness of apixaban compared with warfarin in patients with CrCl <25 mL/min. Included patients were newly initiated on apixaban or warfarin for at least 45 days with a CrCl <25 mL/min. Patients were evaluated for thrombosis and bleeding outcomes 6 months following initiation of anticoagulation. The primary outcome was the time to first bleeding or thrombosis event. A total of 128 patients met inclusion criteria in the apixaban group and 733 patients in the warfarin group. Time to first bleeding or thrombosis event was significantly different between the apixaban and warfarin groups. Cox proportional hazards model was conducted to control for potential confounding factors for the primary outcome. After controlling for atrial fibrillation and coronary artery bypass grafting, risk of thrombotic and bleeding events was lower in the apixaban group (hazard ratio, 0.47; 95% confidence interval, 0.25-0.92). There was not a statistical difference between time to thrombosis (83 days vs 54 days, P = .648), rate of thrombosis (5.5% vs 10.3%, P = .08), time to bleeding (46 days vs 54 days, P = .886), or rate of bleeding (5.5% vs 10.9%, P = .06). The severity of bleeding and thrombotic events was not different between groups. Apixaban may serve as a reasonable alternative compared with warfarin in patients with severe renal dysfunction.

Tracking losses of brevetoxins on exposure to phytoplankton competitors: Mechanistic insights.

The increasing frequency of devastating blooms of the harmful dinoflagellate Karenia brevis has motivated investigations into understanding bloom dynamics and the potential for mitigation. Previous findings indicate that waterborne concentrations of the most abundant brevetoxin (brevetoxin B or PbTx-2) associated with these blooms decrease in the presence of other phytoplankton species. The current study explores the mechanism of brevetoxin removal from seawater upon exposure to phytoplankton competitors. Live phytoplankton removed waterborne brevetoxins more rapidly than lysates, but phytoplankton did not need to be in a state of active metabolism. Biomolecules, probably proteins, exuded from phytoplankton appeared to be responsible for the loss of brevetoxins, either by irreversible complexation or by degradation. Selective removal of PbTx-2 and -1, but not PbTx-3, -9 or BTX-B5, by cultured phytoplankton revealed that brevetoxin removal is dependent upon the presence of an α,ß-unsaturated aldehyde functionality. The mechanism of biotransformation appears to be common among phytoplankton, since members of various taxonomic groups including diatoms, dinoflagellates, and a cryptophyte each caused 75-90% decrease in PbTx-2 concentration, as did a generic protein (bovine serum albumin) added to seawater at high concentration. These findings support the concept of potentially using competitor phytoplankton species or compounds derived from phytoplankton as biocontrol agents for waterborne toxins associated with red tide.