Natural soda lakes provide compatible conditions for RNA and membrane function that could have enabled the origin of life.

The origin of life likely occurred within environments that concentrated cellular precursors and enabled their co-assembly into cells. Soda lakes (those dominated by Na+ ions and carbonate species) can concentrate precursors of RNA and membranes, such as phosphate, cyanide, and fatty acids. Subsequent assembly of RNA and membranes into cells is a long-standing problem because RNA function requires divalent cations, e.g. Mg2+, but Mg2+ disrupts fatty acid membranes. The low solubility of Mg-containing carbonates limits soda lakes to moderate Mg2+ concentrations (∼1 mM), so we investigated whether both RNAs and membranes function within these lakes. We collected water from Last Chance Lake and Goodenough Lake in Canada. Because we sampled after seasonal evaporation, the lake water contained ∼1 M Na+ and ∼1 mM Mg2+ near pH 10. In the laboratory, nonenzymatic, RNA-templated polymerization of 2-aminoimidazole-activated ribonucleotides occurred at comparable rates in lake water and standard laboratory conditions (50 mM MgCl2, pH 8). Additionally, we found that a ligase ribozyme that uses oligonucleotide substrates activated with 2-aminoimidazole was active in lake water after adjusting pH from ∼10 to 9. We also observed that decanoic acid and decanol assembled into vesicles in a dilute solution that resembled lake water after seasonal rains, and that those vesicles retained encapsulated solutes despite salt-induced flocculation when the external solution was replaced with dry-season lake water. By identifying compatible conditions for nonenzymatic and ribozyme-catalyzed RNA assembly, and for encapsulation by membranes, our results suggest that soda lakes could have enabled cellular life to emerge on Earth, and perhaps elsewhere.

The impact of rounds with a psychiatry team in the intensive care unit: A prospective observational pilot study evaluating the effects on delirium incidence and outcomes.

BACKGROUND: Delirium in the intensive care unit (ICU) is a common but serious condition that has been associated with in-hospital mortality and post-discharge psychological dysfunction. The aim of this before and after study is to determine the effect of a multidisciplinary care model entailing daily ICU rounds with a psychiatrist on the incidence of delirium and clinical outcomes. OBJECTIVE: To assess the impact of a proactive psychiatry consultation model in the surgical ICU on the incidence and duration of delirium. METHODS: This was a prospective, single institution, observational controlled cohort pilot study of adult patients admitted to a surgical ICU. A control group that received standard of care (SOC) with daily delirium prevention care bundles in the pre-intervention period was compared to an intervention group, which had a psychiatrist participate in daily ICU rounds (post-intervention period). The primary outcome was delirium incidence. The secondary outcomes were: delirium duration, ventilator days, hospital and ICU length of stay, and in-hospital mortality. RESULTS: A total of 104 patients were enrolled and equally split between SOC and intervention groups; 95 contributed to analysis. The overall incidence of ICU delirium was 19%. SOC and intervention groups had similar rates of delirium (21% vs 18%, p = 0.72). None of the secondary outcomes statistically significantly differed between the two groups. CONCLUSION: Delirium in ICU patients is a potentially preventable condition with serious sequelae. There was no difference in delirium incidence or duration between patients receiving SOC or patients who had multidisciplinary rounds with a psychiatrist.