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Since the post-George Floyd protests and Black Lives Matter/Antifa riots of last summer, the left has become increasingly insistent about the need to "do more" to eliminate what it sees as "systemic racism"--a demand that implicitly, and often explicitly, rejects as woefully inadequate the results of what is by now almost fifty years of affirmative action. The often-dormant resolve of conservatives and others to resist racial preference policies has been aroused by the decisive rejection of Proposition 16 by California voters, the attempt of Democrats to repeal Proposition 209 and revive affirmative action in that state. The gap between elites and popular opinion, between left and right, between Democrats and Republicans, is perhaps wider on this issue than any other. There are virtually no elected or appointed Democrats in federal or state government remaining who believe it is necessary for the state to treat citizens "without regard" to race or ethnicity. Thus even if affirmative action remains as a label, its substance is sure to change. This change will not be the first it has undergone. John S. Rosenburg argues that society should start to think of its next phase as Affirmative Action: Release 3.0.

Consistent buckling distortions of a large membrane patch (200 × 200 Å) are observed during molecular dynamics (MD) simulations using the Monte-Carlo (MC) barostat in combination with a hard Lennard-Jones (LJ) cutoff. The buckling behavior is independent of both the simulation engine and the force field but requires the MC barostat-hard LJ cutoff combination. Similar simulations of a smaller patch (90 × 90 Å) do not show buckling, but do show a small, systematic reduction in the surface area accompanied by ~1 Å thickening suggestive of compression. We show that a mismatch in the way potentials and forces are handled in the dynamical equations versus the MC barostat results in a compressive load on the membrane. Moreover, a straightforward application of elasticity theory reveals that a minimal compression of the linear dimensions of the membrane, inversely proportional to the edge length, is required for buckling, explaining this differential behavior. We recommend always using LJ force or potential-switching when the MC barostat is employed to avoid undesirable membrane deformations.

K2P potassium channels regulate cellular excitability using their selectivity filter (C-type) gate. C-type gating mechanisms, best characterized in homotetrameric potassium channels, remain controversial and are attributed to selectivity filter pinching, dilation, or subtle structural changes. The extent to which such mechanisms control C-type gating of innately heterodimeric K2Ps is unknown. Here, combining K2P2.1 (TREK-1) x-ray crystallography in different potassium concentrations, potassium anomalous scattering, molecular dynamics, and electrophysiology, we uncover unprecedented, asymmetric, potassium-dependent conformational changes that underlie K2P C-type gating. These asymmetric order-disorder transitions, enabled by the K2P heterodimeric architecture, encompass pinching and dilation, disrupt the S1 and S2 ion binding sites, require the uniquely long K2P SF2-M4 loop and conserved "M3 glutamate network," and are suppressed by the K2P C-type gate activator ML335. These findings demonstrate that two distinct C-type gating mechanisms can operate in one channel and underscore the SF2-M4 loop as a target for K2P channel modulator development.

Grabe et al. celebrate a new mathematical model of the multidrug transporter EmrE, constructed from NMR and stop flow kinetic data.

Motivated by growing evidence for pathway heterogeneity and alternative functions of molecular machines, we demonstrate a computational approach for investigating two questions: (1) Are there multiple mechanisms (state-space pathways) by which a machine can perform a given function, such as cotransport across a membrane? (2) How can additional functionality, such as proofreading/error-correction, be built into machine function using standard biochemical processes? Answers to these questions will aid both the understanding of molecular-scale cell biology and the design of synthetic machines. Focusing on transport in this initial study, we sample a variety of mechanisms by employing Metropolis Markov chain Monte Carlo. Trial moves adjust transition rates among an automatically generated set of conformational and binding states while maintaining fidelity to thermodynamic principles and a user-supplied fitness/functionality goal. Each accepted move generates a new model. The simulations yield both single and mixed reaction pathways for cotransport in a simple environment with a single substrate along with a driving ion. In a "competitive" environment including an additional decoy substrate, several qualitatively distinct reaction pathways are found which are capable of extremely high discrimination coupled to a leak of the driving ion, akin to proofreading. The array of functional models would be difficult to find by intuition alone in the complex state-spaces of interest.

Membrane transport is generally thought to occur via an alternating access mechanism in which the transporter adopts at least two states, accessible from two different sides of the membrane to exchange substrates from the extracellular environment and the cytoplasm or from the cytoplasm and the intracellular matrix of the organelles (only in eukaryotes). In recent years, a number of high resolution structures have supported this general framework for a wide class of transport molecules, although additional states along the transport pathway are emerging as critically important. Given that substrate binding is often weak in order to enhance overall transport rates, there exists the distinct possibility that transporters may transport the incorrect substrate. This is certainly the case for many pharmaceutical compounds that are absorbed in the gut or cross the blood brain barrier through endogenous transporters. Docking studies on the bacterial sugar transporter vSGLT reveal that many highly toxic compounds are compatible with binding to the orthosteric site, further motivating the selective pressure for additional modes of selectivity. Motivated by recent work in which we observed failed substrate delivery in a molecular dynamics simulation where the energized ion still goes down its concentration gradient, we hypothesize that some transporters evolved to harness this 'slip' mechanism to increase substrate selectivity and reduce the uptake of toxic molecules. Here, we test this idea by constructing and exploring a kinetic transport model that includes a slip pathway. While slip reduces the overall productive flux, when coupled with a second toxic molecule that is more prone to slippage, the overall substrate selectivity dramatically increases, suppressing the accumulation of the incorrect compound. We show that the mathematical framework for increased substrate selectivity in our model is analogous to the classic proofreading mechanism originally proposed for tRNA synthase; however, because the transport cycle is reversible we identified conditions in which the selectivity is essentially infinite and incorrect substrates are exported from the cell in a 'detoxification' mode. The cellular consequences of proofreading and membrane slippage are discussed as well as the impact on future drug development.

Secondary active transporters, such as those that adopt the leucine-transporter fold, are found in all domains of life, and they have the unique capability of harnessing the energy stored in ion gradients to accumulate small molecules essential for life as well as expel toxic and harmful compounds. How these proteins couple ion binding and transport to the concomitant flow of substrates is a fundamental structural and biophysical question that is beginning to be answered at the atomistic level with the advent of high-resolution structures of transporters in different structural states. Nonetheless, the dynamic character of the transporters, such as ion/substrate binding order and how binding triggers conformational change, is not revealed from static structures, yet it is critical to understanding their function. Here, we report a series of molecular simulations carried out on the sugar transporter vSGLT that lend insight into how substrate and ions are released from the inward-facing state of the transporter. Our simulations reveal that the order of release is stochastic. Functional experiments were designed to test this prediction on the human homolog, hSGLT1, and we also found that cytoplasmic release is not ordered, but we confirmed that substrate and ion binding from the extracellular space is ordered. Our findings unify conflicting published results concerning cytoplasmic release of ions and substrate and hint at the possibility that other transporters in the superfamily may lack coordination between ions and substrate in the inward-facing state.

Sodium-glucose transporters (SGLTs) facilitate the movement of water across the cell membrane, playing a central role in cellular homeostasis. Here, we present a detailed analysis of the mechanism of water permeation through the inward-facing state of vSGLT based on nearly 10 μs of molecular dynamics simulations. These simulations reveal the transient formation of a continuous water channel through the transporter that permits water to permeate the protein. Trajectories in which spontaneous release of galactose is observed, as well as those in which galactose remains in the binding site, show that the permeation rate, although modulated by substrate occupancy, is not tightly coupled to substrate release. Using a, to our knowledge, novel channel-detection algorithm, we identify the key residues that control water flow through the transporter and show that solvent gating is regulated by side-chain motions in a small number of residues on the extracellular face. A sequence alignment reveals the presence of two insertion sites in mammalian SGLTs that flank these outer-gate residues. We hypothesize that the absence of these sites in vSGLT may account for the high water permeability values for vSGLT determined via simulation compared to the lower experimental estimates for mammalian SGLT1.

There is an increasing demand for community-based palliative care services in regional Australia, but feasibility and economic benefits are unclear. This study describes the financial components of service delivery, economic viability from a provider perspective, and potential cost-savings from a health service perspective. We used case study methodology and obtained data from the service provider performance measurement data, annual reports, and internal records. Economic viability included an appraisal of all financial activity, cash on hand, total assets, and liabilities from July 2019 to June 2022. Direct service provision data determined the value for money given total costs and outcomes. Annual cost savings due to decreased utilisation of other healthcare services were estimated using case study data and cost estimates from the literature. The service is largely funded by the government (61%) and community donations & fundraising (34%). Applying a conservative cost estimate based on a reduction of healthcare use (hospitalisations and emergency admissions), cost savings are estimated to range from AU$730 000 to AU$980 000 per year for the cohort of n = 160 clients in the last year of life alone. Average costs per person per year of providing palliative care services were much lower for these clients (AU$6194) compared to the national average for in-home (AU$8000) or hospital-based palliative care services (AU$15 373). The case study site is a viable community-based service but is highly dependent on government funding. It provides excellent value for money from a health service perspective and provides cost saving. Future studies should investigate the generalizability of results. [ABSTRACT FROM AUTHOR]

Background: Little Haven is a rural, community-based specialist palliative care service in Gympie, Australia. Its goals are to provide highest quality of care, support and education for those experiencing or anticipating serious illness and loss. Families and communities work alongside clinical services, with community engagement influencing compassionate care and support of dying people, their families and communities. Public Health Palliative Care promotes community engagement by community-based palliative care services and is grounded in equal partnerships between civic life, community members, patients and carers, and service providers. This takes many forms, including what we have termed the 'citizen organization'. Objectives: This paper reports on an evaluation of Little Haven's model of care and explores the organization's place as a 'citizen' of the community it services. Design: A co-designed evaluation approach utilizing mixed-method design is used. Methods: Multiple data sources obtained a broad perspective of the model of care including primary qualitative data from current patients, current carers, staff, volunteers and organizational stakeholders (interviews and focus groups); and secondary quantitative survey data from bereaved carers. Thematic analysis and descriptive statistics were generated. Results: This model of care demonstrates common service elements including early access to holistic, patient/family-centred, specialized palliative care at little or no cost to users, with strong community engagement. These elements enable high-quality care for patients and carers who describe the support as 'over and above', enabling good quality of life and care at home. Staff and volunteers perceive the built-in flexibility of the model as critical to its outcomes; the interface between the service and the community is similarly stressed as a key service element. Organizational stakeholders observed the model as a product of local activism and accountability to the community. Conclusion: All participant groups agree the service model enables the delivery of excellent care. The construction of a community palliative care service as a citizen organization emerged as a new concept. Plain language summary: 'Citizen organization': an Australian community-based palliative care service model Little Haven is a rural, community-based specialist palliative care service in Gympie, Australia. It aims to provide highest quality of care, support and education for those experiencing or anticipating serious illness and loss. Families and communities work alongside clinical services, with community engagement influencing compassionate care and support of dying people, their families and communities. Public Health Palliative Care promotes community engagement by community-based palliative care services in equal partnerships between civic organizations, community members, patients and carers, and service providers. We undertook an evaluation of Little Haven's model of care by speaking with current patients, current and past carers, staff, volunteers and stakeholders about their experiences of Little Haven. We found that Little Haven's model contains the essential elements of a palliative care service and provides early access to holistic, patient/family-centred, specialized palliative care at little or no cost to users. They have strong community engagement with a strong background in community activism. We identified that Little Haven's 'being in the community' goes beyond service provision or even sentiment. We observed a symbiotic relationship between the organization and the community it supports in what we have termed the 'citizen organization'. The distinctive characteristic of the citizen organization is its inseparability from the community in which it dwells. [ABSTRACT FROM AUTHOR]

Author(s): John S. Rosenberg [sup.1] Author Affiliations: (Aff1) Cambridge, USA Over fifty years ago Daniel Patrick Moynihan, four term U.S. Senator, Ambassador, advisor to presidents, and, perhaps most importantly, distinguished [...]