<i>Bacillus subtilis</i> matrix protein TasA is interfacially active, but BslA dominates interfacial film properties

Microbial growth often occurs within multicellular communities called biofilms, where cells are enveloped by a protective extracellular matrix. Bacillus subtilis serves as a model organism for biofilm research and produces two crucial secreted proteins, BslA and TasA, vital for biofilm matrix formation. BslA exhibits surface-active properties, spontaneously self-assembling at hydrophobic/hydrophilic interfaces to form an elastic protein film which renders B. subtilis biofilm surfaces water-repellent. TasA is traditionally considered a fiber-forming protein with multiple matrix-related functions. In our current study, we investigate whether TasA also possesses interfacial properties and whether it has any impact on BslA’s ability to form an interfacial protein film. Our research demonstrates that TasA indeed exhibits interfacial activity, partitioning to hydrophobic/hydrophilic interfaces, stabilizing emulsions, and forming an interfacial protein film. Interestingly, TasA undergoes interface-induced restructuring similar to BslA, showing an increase in β-strand secondary structure. Unlike BslA, TasA rapidly reaches the interface and forms non-elastic films that rapidly relax under pressure. Through mixed protein pendant drop experiments, we assess the influence of TasA on BslA film formation, revealing that TasA and other surface-active molecules can compete for interface space, potentially preventing BslA from forming a stable elastic film. This raises a critical question: how does BslA self-assemble to form the hydrophobic "raincoat" observed in biofilms in the presence of other potentially surface-active species? We propose a model wherein surface-active molecules, including TasA, initially compete with BslA for interface space. However, under lateral compression or pressure, BslA retains its position, expelling other molecules into the bulk. This resilience at the interface may result from structural rearrangements and lateral interactions between BslA subunits. This combined mechanism likely explains BslA's role in forming a stable film integral to B. subtilis biofilm hydrophobicity

Does Receipt of Recommended Elements of Palliative Care Precede In-Hospital Death or Hospice Referral?

Context. Palliative care aligns treatments with patients’ values and improves quality of life, yet whether receipt of recommended elements of palliative care is associated with end-of-life outcomes is understudied. Objectives. To assess whether recommended elements of palliative care (pain and symptom management, goals of care, and spiritual care) precede in-hospital death and hospice referral and whether delivery by specialty palliative care affects that relationship. Methods. We conducted structured chart reviews for decedents with late-stage cancer, dementia, and chronic kidney disease with a hospital admission during the six months preceding death. Measures included receipt of recommended elements of palliative care delivered by any clinician and specialty palliative care consult. We assessed associations between recommended elements of palliative care and in-hospital death and hospice referral using multivariable Poisson regression models. Results. Of 402 decedents, 67 (16.7%) died in hospital, and 168 (41.8%) had hospice referral. Among elements of palliative care, only goals-of-care discussion was associated with in-hospital death (incidence rate ratio [IRR] 1.37; 95% CI 1.01e1.84) and hospice referral (IRR 1.85; 95% CI 1.31e2.61). Specialty palliative care consult was associated with a lower likelihood of in-hospital death (IRR 0.57; 95% CI 0.44e0.73) and a higher likelihood of hospice referral (IRR 1.45; 95% CI 1.12e1.89) compared with no consult. Conclusion. Goals-of-care discussions by different types of clinicians commonly precede end-of-life care in hospital or hospice. However, engagement with specialty palliative care reduced in-hospital death and increased hospice referral. Understanding the causal pathways of goals-of-care discussions may help build primary palliative care interventions to support patients near the end of life

Elements of Palliative Care in the Last 6 Months of Life: Frequency, Predictors, and Timing

IMPORTANCE: Persons living with serious illness often need skilled symptom management, communication, and spiritual support. Palliative care addresses these needs and may be delivered by either specialists or clinicians trained in other fields. It is important to understand core elements of palliative care to best provide patient-centered care. OBJECTIVE: To describe frequency, predictors, and timing of core elements of palliative care during the last 6 months of life. DESIGN: Retrospective chart review. SETTING: Inpatient academic medical center. PARTICIPANTS: Decedents with cancer, dementia, or chronic kidney disease (CKD) admitted during the 6 months preceding death. EXPOSURES: We identified receipt and timing of core elements of palliative care: pain and symptom management, goals of care, spiritual care; and specialty palliative care utilization; hospital encounters; demographics; and comorbid diagnoses.We ran Poisson regression models to assess whether diagnosis or hospital encounters were associated with core elements of palliative care. RESULTS: Among 402 decedents, themean (SD) number of appropriately screened and treated symptoms was 2.9 (1.7)/10. Among 76.1% with documented goals of care, 58.0% had a primary goal of comfort; 55.0% had documented spiritual care. In multivariable models, compared with decedents with cancer, those with dementia or CKD were less likely to have pain and symptom management (respectively, 31% (incidence rate ratio [IRR], 0.69; 95% CI, 0.56–0.85) and 17% (IRR, 0.83; CI, 0.71–0.97)). There was amedian of 3 days (IQR, 0–173) between transition to a goal of comfort and death, and amedian of 12 days (IQR, 5–47) between hospice referral and death. CONCLUSIONS AND RELEVANCE: Although a high proportion of patients received elements of palliative care, transitions to a goal of comfort or hospice happened very near death. Palliative care delivery can be improved by systematizing existing mechanisms, including prompts for earlier goals-of-care discussion, symptom screening, and spiritual care, and by building collaboration between primary and specialty palliative care services

Electronic Health Record Phenotypes for Identifying Patients with Late-Stage Disease: a Method for Research and Clinical Application

BACKGROUND: Systematic identification of patients allows researchers and clinicians to test new models of care delivery. EHR phenotypes—structured algorithms based on clinical indicators from EHRs—can aid in such identification. OBJECTIVE: To develop EHR phenotypes to identify decedents with stage 4 solid-tumor cancer or stage 4–5 chronic kidney disease (CKD). DESIGN: We developed two EHR phenotypes. Each phenotype included International Classification of Diseases (ICD)-9 and ICD-10 codes. We used natural language processing (NLP) to further specify stage 4 cancer, and lab values for CKD. SUBJECTS: Decedents with cancer or CKD who had been admitted to an academic medical center in the last 6 months of life and died August 26, 2017–December 31, 2017. MAIN MEASURE: We calculated positive predictive values (PPV), false discovery rates (FDR), false negative rates (FNR), and sensitivity. Phenotypes were validated by a comparison with manual chart review. We also compared the EHR phenotype results to those admitted to the oncology and nephrology inpatient services. KEY RESULTS: The EHR phenotypes identified 271 decedents with cancer, of whom 186 had stage 4 disease; of 192 decedents with CKD, 89 had stage 4–5 disease. The EHR phenotype for stage 4 cancer had a PPV of 68.6%, FDR of 31.4%, FNR of 0.5%, and 99.5% sensitivity. The EHR phenotype for stage 4–5 CKD had a PPV of 46.4%, FDR of 53.7%, FNR of 0.0%, and 100% sensitivity. CONCLUSIONS: EHR phenotypes efficiently identified patients who died with late-stage cancer or CKD. Future EHR phenotypes can prioritize specificity over sensitivity, and incorporate stratification of high- and low-palliative care need. EHR phenotypes are a promising method for identifying patients for research and clinical purposes, including equitable distribution of specialty palliative care

Architecture of Kepler's Multi-transiting Systems: II. New investigations with twice as many candidates

We report on the orbital architectures of Kepler systems having multiple planet candidates identified in the analysis of data from the first six quarters of Kepler data and reported by Batalha et al. (2013). These data show 899 transiting planet candidates in 365 multiple-planet systems and provide a powerful means to study the statistical properties of planetary systems. Using a generic mass-radius relationship, we find that only two pairs of planets in these candidate systems (out of 761 pairs total) appear to be on Hill-unstable orbits, indicating ~96% of the candidate planetary systems are correctly interpreted as true systems. We find that planet pairs show little statistical preference to be near mean-motion resonances. We identify an asymmetry in the distribution of period ratios near first-order resonances (e.g., 2:1, 3:2), with an excess of planet pairs lying wide of resonance and relatively few lying narrow of resonance. Finally, based upon the transit duration ratios of adjacent planets in each system, we find that the interior planet tends to have a smaller transit impact parameter than the exterior planet does. This finding suggests that the mode of the mutual inclinations of planetary orbital planes is in the range 1.0-2.2 degrees, for the packed systems of small planets probed by these observations.Comment: Accepted to Ap

Lateral interactions govern self-assembly of the bacterial biofilm matrix protein BslA

The soil bacterium Bacillus subtilis is a model organism to investigate the formation of biofilms, the predominant form of microbial life. The secreted protein BslA self-assembles at the surface of the biofilm to give the B. subtilis biofilm its characteristic hydrophobicity. To understand the mechanism of BslA self-assembly at interfaces, here we built a molecular model based on the previous BslA crystal structure and the crystal structure of the BslA paralogue YweA that we determined. Our analysis revealed two conserved protein-protein interaction interfaces supporting BslA self-assembly into an infinite 2-dimensional lattice that fits previously determined transmission microscopy images. Molecular dynamics simulations and in vitro protein assays further support our model of BslA elastic film formation, while mutagenesis experiments highlight the importance of the identified interactions for biofilm structure. Based on this knowledge, YweA was engineered to form more stable elastic films and rescue biofilm structure in bslA deficient strains. These findings shed light on protein film assembly and will inform the development of BslA technologies which range from surface coatings to emulsions in fast-moving consumer goods.</p