Cellular membranes are densely crowded with a diverse population of integral and membrane-associated proteins. In this complex environment, lipid rafts, which are phase-separated membrane domains enriched in cholesterol and saturated lipids, are thought to organize the membrane surface. Specifically, rafts may help to concentrate proteins and lipids locally, enabling cellular processes such as assembly of caveolae, budding of enveloped viruses, and sorting of lipids and proteins in the Golgi. However, the ability of rafts to concentrate protein species has not been quantified experimentally. Here we show that when membrane-bound proteins become densely crowded within liquid-ordered membrane regions, steric pressure arising from collisions between proteins can destabilize lipid phase separations, resulting in a homogeneous distribution of proteins and lipids over the membrane surface. Using a reconstituted system of lipid vesicles and recombinant proteins, we demonstrate that protein-protein steric pressure creates an energetic barrier to the stability of phase-separated membrane domains that increases in significance as the molecular weight of the proteins increases. Comparison with a simple analytical model reveals that domains are destabilized when the steric pressure exceeds the approximate enthalpy of membrane mixing. These results suggest that a subtle balance of free energies governs the stability of phase-separated cellular membranes, providing a new perspective on the role of lipid rafts as concentrators of membrane proteins.

BACKGROUND: Value congruence (VC) is the degree of alignment between worker and workplace values and is strongly associated with reduced job strain and retention. Within general surgery residency, the impact of VC and how to operationalize it to improve workplace well-being remain unclear. STUDY DESIGN: This 2-part mixed-methods study comprised 2 surveys of US general surgery residents and qualitative interviews with program directors. In Part 1, January 2021, mixed-level surgical residents from 16 ACGME-accredited general surgery residency programs participated in survey #1. This survey was used to identify shared or conflicting perspectives on VC concerning well-being initiatives and resources. In April 2021, interviews from 8 institutions were conducted with 9 program directors or their proxies. In Part 2, May to June 2022, a similar cohort of surgical residents participated in survey #2. Unadjusted logistic and linear regression models were used in this survey to assess the association between VC and individual-level global well-being (ie flourishing), respectively. RESULTS: In survey #1 (N = 300, 34% response rate), lack of VC was an emergent theme with subthemes of inaccessibility, inconsiderateness, inauthenticity, and insufficiency regarding well-being resources. Program directors expressed variable awareness of and alignment with these perceptions. In survey #2 (N = 251, 31% response rate), higher VC was significantly associated with flourishing (odds ratio 1.91, 95% CI 1.44 to 2.52, p < 0.001). CONCLUSIONS: Exploring the perceived lack of VC within general surgery residency reveals an important cultural variable for optimizing well-being and suggests open dialogue as a first step toward positive change. Future work to identify where and how institutional actions diminish perceived VC is warranted.

Purpose Physician wellbeing is critical to high-quality sustainable healthcare and optimal patient experience. Few objective measures exist to assay wellbeing (as opposed to just pathology) in surgery, or to evaluate the efficacy of wellbeing interventions. Flourishing (as measured by the Mental Health Continuum, MHC) has been suggested as a concise measure of global wellbeing in surgeons. We aimed to establish validity evidence for flourishing in a large national sample of surgical trainees, explore differences by gender and race, and confirm support for the underlying constructs. Methods This cross-sectional study of all General Surgery residents at 16 ACGME-accredited academic programs included an online survey of published measures distributed in February 2021. The Mental Health Continuum (MHC), a three-factor model, assesses emotional, social, and psychological wellbeing and is an established metric of psychosocial thriving in non-physicians. A global score cut-off exists for flourishing which represents high wellbeing. Correlation between flourishing and established measures of risk and resilience in surgery were assessed for validity evidence. Differences by gender and race were explored. A confirmatory factor analysis (CFA) was performed to confirm the three-factor structure in surgical trainees. Results 300 residents (60% non-male, 41% non-white) responded to the survey. For the overall group, flourishing was significantly positively correlated with all wellbeing resilience factors and negatively correlated with all risk factors. This held true for race and gender subgroups based on interaction analyses. CFA and sensitivity analysis results supported the three-factor structure. Conclusions Our findings offer validity evidence for flourishing as a measure of global wellbeing and confirm the three-factor structure of emotional, social, and psychological wellbeing in surgical trainees. Thus, the MHC may be a concise tool for assaying wellbeing, within and across subgroups, and for assessing wellbeing intervention effectiveness within the surgery.

have a cholate backbone with polar groups extending from one face and a short alkyl chain extending from the opposite face. FA-solubilized Cx26 crystallized into the H32 space group with two monomers in the asymmetric unit, and the crystals diffracted isotropically to 3.3-Å resolution. Using a molecular replacement search model based on a cryoEM map of Cx43 at 5.7-Å resolution [Fleishman et al., Mol. Cell 15: 879-888 (2004)], we solved the structure independently from a previously reported 3.5-Å resolution X-ray structure [2ZW3, Maeda et al., Nature 458: 597-602 (2009)]. The overall R/Rfree values and completeness were 0.311/0.328 and 98.9%, respectively, and the Molprobity score was 2.07 (100 th percentile). The RMS differences between 2ZW3 and our structure were 0.9 and 1.7-Å for the main-chain and side-chain atoms in the TM helices and 1.3 and 1.9-Å for the main-chain and side-chain atoms in E1 and E2. Although the topology and fold recapitulated 2ZW3, the maximum differences were significant: 2.7 and 5.9-Å for the main chain and side chain atoms in the TM helices and 3.9 and 7.6-Å for the main-chain and side-chain atoms in E1 and E2. We generated an electron density map at a resolution comparable to the cryoEM structure of the authentic Cx43 channel. The similarity of the maps suggests that detergent-solubilized Cx26 that crystallized as a dodecamer represents the authentic gap junction channel.

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