Interprofessional bedside rounding improves quality of feedback to resident physicians.

PURPOSE: Obtaining high quality feedback in residency education is challenging, in part due to limited opportunities for faculty observation of authentic clinical work. This study reviewed the impact of interprofessional bedside rounds ('iPACE™') on the length and quality of faculty narrative evaluations of residents as compared to usual inpatient teaching rounds. METHODS: Narrative comments from faculty evaluations of Internal Medicine (IM) residents both on usual teaching service as well as the iPACE™ service (spanning 2017-2020) were reviewed and coded using a deductive content analysis approach. RESULTS: Six hundred ninety-two narrative evaluations by 63 attendings of 103 residents were included. Evaluations of iPACE™ residents were significantly longer than those of residents on usual teams (109 vs. 69 words, p < 0.001). iPACE™ evaluations contained a higher average occurrence of direct observations of patient/family interactions (0.72 vs. 0.32, p < 0.001), references to interprofessionalism (0.17 vs. 0.05, p < 0.001), as well as specific (3.21 vs. 2.26, p < 0.001), actionable (1.01 vs. 0.69, p < 0.001), and corrective feedback (1.2 vs. 0.88, p = 0.001) per evaluation. CONCLUSIONS: This study suggests that the iPACE™ model, which prioritizes interprofessional bedside rounds, had a positive impact on the quantity and quality of feedback, as measured via narrative comments on weekly evaluations.

Recovery of Fatty Acids from Mineralogic Mars Analogs by TMAH Thermochemolysis for the Sample Analysis at Mars Wet Chemistry Experiment on the Curiosity Rover.

The Mars Curiosity rover carries a diverse instrument payload to characterize habitable environments in the sedimentary layers of Aeolis Mons. One of these instruments is Sample Analysis at Mars (SAM), which contains a mass spectrometer that is capable of detecting organic compounds via pyrolysis gas chromatography mass spectrometry (py-GC-MS). To identify polar organic molecules, the SAM instrument carries the thermochemolysis reagent tetramethylammonium hydroxide (TMAH) in methanol (hereafter referred to as TMAH). TMAH can liberate fatty acids bound in macromolecules or chemically bound monomers associated with mineral phases and make these organics detectable via gas chromatography mass spectrometry (GC-MS) by methylation. Fatty acids, a type of carboxylic acid that contains a carboxyl functional group, are of particular interest given their presence in both biotic and abiotic materials. This work represents the first analyses of a suite of Mars-analog samples using the TMAH experiment under select SAM-like conditions. Samples analyzed include iron oxyhydroxides and iron oxyhydroxysulfates, a mixture of iron oxides/oxyhydroxides and clays, iron sulfide, siliceous sinter, carbonates, and shale. The TMAH experiments produced detectable signals under SAM-like pyrolysis conditions when organics were present either at high concentrations or in geologically modern systems. Although only a few analog samples exhibited a high abundance and variety of fatty acid methyl esters (FAMEs), FAMEs were detected in the majority of analog samples tested. When utilized, the TMAH thermochemolysis experiment on SAM could be an opportunity to detect organic molecules bound in macromolecules on Mars. The detection of a FAME profile is of great astrobiological interest, as it could provide information regarding the source of martian organic material detected by SAM.

Metabolic Processes Preserved as Biosignatures in Iron-Oxidizing Microorganisms: Implications for Biosignature Detection on Mars.

Iron-oxidizing bacteria occupy a distinct environmental niche. These chemolithoautotrophic organisms require very little oxygen (when neutrophilic) or outcompete oxygen for access to Fe(II) (when acidophilic). The utilization of Fe(II) as an electron donor makes them strong analog organisms for any potential life that could be found on Mars. Despite their importance to the elucidation of early life on, and potentially beyond, Earth, many details of their metabolism remain unknown. By using on-line thermochemolysis and gas chromatography-mass spectrometry (GC-MS), a distinct signal for a low-molecular-weight molecule was discovered in multiple iron-oxidizing isolates as well as several iron-dominated environmental samples, from freshwater and marine environments and in both modern and older iron rock samples. This GC-MS signal was neither detected in organisms that did not use Fe(II) as an electron donor nor present in iron mats in which organic carbon was destroyed by heating. Mass spectral analysis indicates that the molecule bears the hallmarks of a pterin-bearing molecule. Genomic analysis has previously identified a molybdopterin that could be part of the electron transport chain in a number of lithotrophic iron-oxidizing bacteria, suggesting one possible source for this signal is the pterin component of this protein. The rock samples indicate the possibility that the molecule can be preserved within lithified sedimentary rocks. The specificity of the signal to organisms requiring iron in their metabolism makes this a novel biosignature with which to investigate both the evolution of life on ancient Earth and potential life on Mars.

The origin and implications of clay minerals from Yellowknife Bay, Gale crater, Mars.

The Mars Science Laboratory (MSL) rover Curiosity has documented a section of fluvio-lacustrine strata at Yellowknife Bay (YKB), an embayment on the floor of Gale crater, approximately 500 m east of the Bradbury landing site. X-ray diffraction (XRD) data and evolved gas analysis (EGA) data from the CheMin and SAM instruments show that two powdered mudstone samples (named John Klein and Cumberland) drilled from the Sheepbed member of this succession contain up to ~20 wt% clay minerals. A trioctahedral smectite, likely a ferrian saponite, is the only clay mineral phase detected in these samples. Smectites of the two samples exhibit different 001 spacing under the low partial pressures of H2O inside the CheMin instrument (relative humidity <1%). Smectite interlayers in John Klein collapsed sometime between clay mineral formation and the time of analysis to a basal spacing of 10 Å, but largely remain open in the Cumberland sample with a basal spacing of ~13.2 Å. Partial intercalation of Cumberland smectites by metal-hydroxyl groups, a common process in certain pedogenic and lacustrine settings on Earth, is our favored explanation for these differences. The relatively low abundances of olivine and enriched levels of magnetite in the Sheepbed mudstone, when compared with regional basalt compositions derived from orbital data, suggest that clay minerals formed with magnetite in situ via aqueous alteration of olivine. Mass-balance calculations are permissive of such a reaction. Moreover, the Sheepbed mudstone mineral assemblage is consistent with minimal inputs of detrital clay minerals from the crater walls and rim. Early diagenetic fabrics suggest clay mineral formation prior to lithification. Thermodynamic modeling indicates that the production of authigenic magnetite and saponite at surficial temperatures requires a moderate supply of oxidants, allowing circum-neutral pH. The kinetics of olivine alteration suggest the presence of fluids for thousands to hundreds of thousands of years. Mineralogical evidence of the persistence of benign aqueous conditions at YKB for extended periods indicates a potentially habitable environment where life could establish itself. Mediated oxidation of Fe2+ in olivine to Fe3+ in magnetite, and perhaps in smectites provided a potential energy source for organisms.

Compact two-step laser time-of-flight mass spectrometer for in situ analyses of aromatic organics on planetary missions.

RATIONALE: A miniature time-of-flight mass spectrometer measuring 20 cm in length has been adapted to demonstrate two-step laser desorption/ionization (LDI) in a compact instrument package for enhanced organics detection. Two-step LDI decouples the desorption and ionization processes, relative to traditional LDI, in order to produce low-fragmentation mass spectra of organic analytes. Tuning the UV ionization laser energy would allow control of the degree of fragmentation, which might enable better identification of constituent species. METHODS: A reflectron time-of-flight mass spectrometer prototype was modified to allow a two-laser configuration, with IR (1064 nm) desorption followed by UV (266 nm) postionization. A relatively low ion extraction voltage of 5 kV was applied at the sample inlet. RESULTS: The instrument capabilities and performance were demonstrated with analysis of a model polycyclic aromatic hydrocarbon, representing a class of compounds important to the fields of Earth and planetary science. Two-step laser mass spectrometry (L2MS) analysis of a model PAH, pyrene, was demonstrated, including molecular ion identification and the onset of tunable fragmentation as a function of ionizing laser energy. Mass resolution m/Δm = 380 at full width at half-maximum was achieved for gas-phase postionization of desorbed neutrals in this highly compact mass analyzer. CONCLUSIONS: Achieving L2MS in a highly miniaturized instrument enables a powerful approach to the detection and characterization of aromatic organics in remote terrestrial and planetary applications. Tunable detection of molecular and fragment ions with high mass resolution, diagnostic of molecular structure, is possible on such a compact L2MS instrument. The selectivity of L2MS against low-mass inorganic salt interferences is a key advantage when working with unprocessed, natural samples, and a mechanism for the observed selectivity is proposed.

Enrichment and isolation of iron-oxidizing bacteria at neutral pH.

Methods are provided for the culture of neutrophilic Fe-oxidizing bacteria (FeOB) that grow under microaerobic and anaerobic conditions. For oxygen-requiring lithotrophic Fe oxidizers, it is essential that both O2 and Fe(II) concentrations are kept low, but that an adequate flux of both O2 and Fe(II) are provided to support growth. Techniques using opposing gradients of Fe(II) and O2 are discussed. Preparation of stock solutions of FeS and FeCl2 are described. Methods for the culture of anaerobic FeOB that utilize nitrate or light (anoxygenic photosynthesis) are discussed and presented briefly.