Ketamine for postoperative avoidance of depressive symptoms: the K-PASS feasibility randomised trial.

Background: Surgical patients with previous depression frequently experience postoperative depressive symptoms. This study's objective was to determine the feasibility of a placebo-controlled trial testing the impact of a sustained ketamine infusion on postoperative depressive symptoms. Methods: This single-centre, triple-blind, placebo-controlled randomised clinical trial included adult patients with depression scheduled for inpatient surgery. After surgery, patients were randomly allocated to receive ketamine (0.5 mg kg-1 over 10 min followed by 0.3 mg kg-1 h-1 for 3 h) or an equal volume of normal saline. Depressive symptoms were measured using the Montgomery-Asberg Depression Rating Scale. On post-infusion day 1, participants guessed which intervention they received. Feasibility endpoints included the fraction of patients approached who were randomised, the fraction of randomised patients who completed the study infusion, and the fraction of scheduled depression assessments that were completed. Results: In total, 32 patients were allocated a treatment, including 31/101 patients approached after a protocol change (31%, 1.5 patients per week). The study infusion was completed without interruption in 30/32 patients (94%). In each group, 7/16 participants correctly guessed which intervention they received. Depression assessments were completed at 170/192 scheduled time points (89%). Between baseline and post-infusion day 4 (pre-specified time point of interest), median depressive symptoms decreased in both groups, with difference-in-differences of -1.00 point (95% confidence interval -3.23 to 1.73) with ketamine compared with placebo. However, the between-group difference did not persist at other time points. Conclusions: Patient recruitment, medication administration, and clinical outcome measurement appear to be highly feasible, with blinding maintained. A fully powered trial may be warranted. Clinical trial registration: NCT05233566.

Effect of gut microbiota on α-amanitin tolerance in Drosophila tripunctata.

The bacterial gut microbiota of many animals is known to be important for many physiological functions including detoxification. The selective pressures imposed on insects by exposure to toxins may also be selective pressures on their symbiotic bacteria, who thus may contribute to the mechanism of toxin tolerance for the insect. Amatoxins are a class of cyclopeptide mushroom toxins that primarily act by binding to RNA polymerase II and inhibiting transcription. Several species of mycophagous Drosophila are tolerant to amatoxins found in mushrooms of the genus Amanita, despite these toxins being lethal to most other known eukaryotes. These species can tolerate amatoxins in natural concentrations to utilize toxic mushrooms as larval hosts, but the mechanism by which these species are tolerant remains unknown. Previous data have shown that a local population of D. tripunctata exhibits significant genetic variation in toxin tolerance. This study assesses the potential role of the microbiome in α-amanitin tolerance in six wild-derived strains of Drosophila tripunctata. Normal and antibiotic-treated samples of six strains were reared on diets with and without α-amanitin, and then scored for survival from the larval stage to adulthood and for development time to pupation. Our results show that a substantial reduction in bacterial load does not influence toxin tolerance in this system, while confirming genotype and toxin-specific effects on survival are independent of the microbiome composition. Thus, we conclude that this adaptation to exploit toxic mushrooms as a host is likely intrinsic to the fly's genome and not a property of their microbiome.

Exhaustive extraction of cyclopeptides from Amanita phalloides: Guidelines for working with complex mixtures of secondary metabolites.

Understanding plant-insect interactions is an active area of research in both ecology and evolution. Much attention has been focused on the impact of secondary metabolites in the host plant or fungi on these interactions. Plants and fungi contain a variety of biologically active compounds, and the secondary metabolite profile can vary significantly between individual samples. However, many experiments characterize the biological effects of only a single secondary metabolite or a subset of these compounds.Here, we develop an exhaustive extraction protocol using an accelerated solvent extraction protocol to recover the complete suite of cyclopeptides and other secondary metabolites found in Amanita phalloides (death cap mushrooms) and compare its efficacy to the "Classic" extraction method used in earlier works.We demonstrate that our extraction protocol recovers the full suite of cyclopeptides and other secondary metabolites in A. phalloides unlike the "Classic" method that favors polar cyclopeptides.Based on these findings, we provide recommendations for how to optimize protocols to ensure exhaustive extracts and also the best practices when using natural extracts in ecological experiments.