Structural basis of the allosteric trigger of the Hsp70 chaperone proteins.

This work solves a decades-old dilemma that stood in the way of understanding the allosteric mechanism of Hsp70 (heat shock 70 kDa) chaperone proteins. Hsp70s are central to protein folding, refolding, and trafficking in organisms ranging from Archae to Homo Sapiens, both at normal and at stressed cellular conditions. Hsp70s are comprised of two main domains: a 44 kDa N-terminal nucleotide-binding domain (NBD), and a 25 kDa substrate-binding domain (SBD) that harbors the substrate binding site. The nucleotide binding site in the NBD and the substrate binding site in the SBD are allosterically linked: ADP binding promotes substrate binding, while ATP binding promotes substrate release. It has long been a goal of structural biology to characterize the nature of the allosteric coupling in these proteins. However, even the most sophisticated X-ray crystallography studies of the isolated NBD could show no difference in overall conformation between the ATP and ADP state. Hence the dilemma: how is the state of the nucleotide communicated between NBD and SBD? The solution of the dilemma is especially interesting in light of the fact that Hsp70s are ancient proteins, and amongst the first allosteric proteins in nature.Here we report a solution NMR study of the NBD of the Hsp70 from Thermus thermophilus, in the APO, ADP and AMP-PNP states, where the latter is a non-hydrolysable ATP analogue. Using the modern NMR methods of residual dipolar coupling analysis, we discovered that the nucleotide binding cleft opens up by as much as 20 degrees between the AMP-PNP (closed) and ADP (open) state. We also discover that a surface cleft, hypothesized to be essential for the allosteric coupling between NBD and SBD, echoes these changes. Hence, the nature of the allosteric trigger and coupling for Hsp70 chaperones is revealed here for the first time, solving the dilemma

Reshaping surgical specialist training in small animal surgery during and after the COVID ‐19 pandemic

Abstract: Objective: To assess the perceived effects of the COVID‐19 pandemic on small animal surgical specialist training, among trainees and supervisors and to propose changes, based upon the results, that could be incorporated into training programs. Study Design: Anonymous online questionnaire survey. Sample Population: Eighty‐one eligible responses were collected in September 2020, including 52 European College of Veterinary Surgeons (ECVS) residents and 29 ECVS Diplomates acting as supervisors. Methods: Descriptive statistics were used to analyze the data. Fisher's exact test was used to test for significance. Results: A reduction in surgical case load was reported by 82% (n = 66/81) of respondents, with 82% (n = 54/66) of those believing that COVID‐19 had a mild‐to‐moderate impact on training. Compared to supervisors, residents were less likely to feel that appropriate guidance, a safe working environment, and measures to preserve training had been provided (p < .01). Only 45% (n = 22/49) of residents reported confidence with performing teleconsultations. Ninety percent (n = 73/81) of respondents considered online “case presentations” and “edited surgical video footage” as a positive ancillary tool. Conclusion: COVID‐19 has resulted in a reduction in case load and training for the majority of residents. A discrepancy between the opinions of residents and supervisors was noted on various aspects of COVID‐19 related effects. Impact: Open communication, as well as the use of additional training tools through digital platforms may help to preserve safe and effective training during times of decreased clinical activity. While this study has focused on surgical specialist training, the results could be applied to other disciplines

Reshaping surgical specialist training in small animal surgery during and after the COVID ‐19 pandemic

Abstract: Objective: To assess the perceived effects of the COVID‐19 pandemic on small animal surgical specialist training, among trainees and supervisors and to propose changes, based upon the results, that could be incorporated into training programs. Study Design: Anonymous online questionnaire survey. Sample Population: Eighty‐one eligible responses were collected in September 2020, including 52 European College of Veterinary Surgeons (ECVS) residents and 29 ECVS Diplomates acting as supervisors. Methods: Descriptive statistics were used to analyze the data. Fisher's exact test was used to test for significance. Results: A reduction in surgical case load was reported by 82% (n = 66/81) of respondents, with 82% (n = 54/66) of those believing that COVID‐19 had a mild‐to‐moderate impact on training. Compared to supervisors, residents were less likely to feel that appropriate guidance, a safe working environment, and measures to preserve training had been provided (p < .01). Only 45% (n = 22/49) of residents reported confidence with performing teleconsultations. Ninety percent (n = 73/81) of respondents considered online “case presentations” and “edited surgical video footage” as a positive ancillary tool. Conclusion: COVID‐19 has resulted in a reduction in case load and training for the majority of residents. A discrepancy between the opinions of residents and supervisors was noted on various aspects of COVID‐19 related effects. Impact: Open communication, as well as the use of additional training tools through digital platforms may help to preserve safe and effective training during times of decreased clinical activity. While this study has focused on surgical specialist training, the results could be applied to other disciplines

Behavior Trees with Dataflow: Coordinating Reactive Tasks in Lingua Franca

Behavior Trees (BTs) provide a lean set of control flow elements that are easily composable in a modular tree structure. They are well established for modeling the high-level behavior of non-player characters in computer games and recently gained popularity in other areas such as industrial automation. While BTs nicely express control, data handling aspects so far must be provided separately, e. g. in the form of blackboards. This may hamper reusability and can be a source of nondeterminism. We here present a dataflow extension to BTs that explicitly models data relations and communication. We provide a combined textual/graphical approach in line with modern, productivity-enhancing pragmatics-aware modeling techniques. We realized and validated that approach in the recently introduced polyglot coordination language Lingua Franca (LF)

The NANOGrav 15 yr Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational-wave Background

El conjunto de datos de 15 años de NANOGrav muestra evidencias de la presencia de un fondo de ondas gravitacionales (GWB) de baja frecuencia. Aunque muchos procesos físicos pueden originar estas ondas gravitacionales de baja frecuencia, aquí analizamos la señal como procedente de una población de agujeros negros binarios supermasivos (SMBH) distribuidos por todo el Universo. Demostramos que los modelos astrofísicos de poblaciones binarias SMBH son capaces de reproducir tanto la amplitud como la forma del espectro de ondas gravitacionales de baja frecuencia observado. Aunque múltiples variaciones del modelo son capaces de reproducir el espectro GWB con nuestra precisión de medida actual, nuestros resultados subrayan la importancia de modelar con precisión la evolución binaria para producir espectros GWB realistas. Además, aunque unos parámetros razonables son capaces de reproducir las observaciones de 15 años, la amplitud implícita del GWB requiere que un gran número de parámetros se sitúen en los límites de los valores esperados o que un pequeño número de parámetros difieran notablemente de las expectativas estándar. Aunque todavía no somos capaces de establecer definitivamente el origen de la señal GWB inferida, la consistencia de la señal con las expectativas astrofísicas ofrece una perspectiva tentadora para confirmar que las binarias SMBH son capaces de formarse, alcanzar separaciones de sub-segundos y finalmente unirse. A medida que la importancia aumente con el tiempo, las características de orden superior del espectro del GWB determinarán definitivamente la naturaleza del GWB y permitirán nuevas restricciones sobre las poblaciones de SMBH. © 2023The NANOGrav 15 yr data set shows evidence for the presence of a low-frequency gravitational-wave background (GWB). While many physical processes can source such low-frequency gravitational waves, here we analyze the signal as coming from a population of supermassive black hole (SMBH) binaries distributed throughout the Universe. We show that astrophysically motivated models of SMBH binary populations are able to reproduce both the amplitude and shape of the observed low-frequency gravitational-wave spectrum. While multiple model variations are able to reproduce the GWB spectrum at our current measurement precision, our results highlight the importance of accurately modeling binary evolution for producing realistic GWB spectra. Additionally, while reasonable parameters are able to reproduce the 15 yr observations, the implied GWB amplitude necessitates either a large number of parameters to be at the edges of expected values or a small number of parameters to be notably different from standard expectations. While we are not yet able to definitively establish the origin of the inferred GWB signal, the consistency of the signal with astrophysical expectations offers a tantalizing prospect for confirming that SMBH binaries are able to form, reach subparsec separations, and eventually coalesce. As the significance grows over time, higher-order features of the GWB spectrum will definitively determine the nature of the GWB and allow for novel constraints on SMBH populations. © 2023. The Author(s). Published by the American Astronomical Society

Almanac: Retrieval-Augmented Language Models for Clinical Medicine

Large-language models have recently demonstrated impressive zero-shot capabilities in a variety of natural language tasks such as summarization, dialogue generation, and question-answering. Despite many promising applications in clinical medicine, adoption of these models in real-world settings has been largely limited by their tendency to generate incorrect and sometimes even toxic statements. In this study, we develop Almanac, a large language model framework augmented with retrieval capabilities for medical guideline and treatment recommendations. Performance on a novel dataset of clinical scenarios (n = 130) evaluated by a panel of 5 board-certified and resident physicians demonstrates significant increases in factuality (mean of 18% at p-value < 0.05) across all specialties, with improvements in completeness and safety. Our results demonstrate the potential for large language models to be effective tools in the clinical decision-making process, while also emphasizing the importance of careful testing and deployment to mitigate their shortcomings

Timing of Preoperative Surgical Antibiotic Prophylaxis Prior to One-to-Three Level Elective Lumbar Fusion

Introduction: Surgical site infections (SSIs) in patients who have undergone lumbar fusion surgery can be a devastating complication. The aim of this study was to examine the relationship between timing of preoperative antibiotic prophylaxis and adverse outcomes such as SSIs with subgroup analysis stratified by antibiotic type. Methods: This retrospective cohort included patients having undergone a 1-3 level lumbar fusion who were allocated into 5 groups based on the time from antibiotic administration to incision (Group A = 0-15 min, Group B = 16-30 min, Group C = 31-45 min, Group D = 46 – 60 min, and Group E = 61+ min). The primary outcome was SSIs, with secondary outcomes including: 90-day readmission and revision surgery. Statistical analysis, including a logistic regression model, was used to examine the relationship between patient/case characteristics, preoperative antibiotic timing, and postoperative outcomes. Results: From 1,131 patients, 26 SSIs were identified. Logistic regression analysis revealed that Group E patients were 1.4 times more likely to develop an SSI and 7.2 times more likely to be readmitted within 90 days compared to Group A. Furthermore, Groups B-D did not have significantly higher odds of infection compared to Group A. Patients treated with vancomycin showed the lowest incidence of SSI when administered between 16-30 minutes, however cefazolin showed the lowest incidence when administered between 0-15 minutes. Discussion: Preoperative antibiotic administration beyond one hour is associated with higher rates of SSI. Furthermore, vancomycin use is optimal when administered between 16 and 30 minutes prior to incision. While antibiotic prophylaxis effects depend on patient characteristics and varying pharmacokinetics, an effective regimen can significantly improve patient outcomes

Development and Implementation of an Academic-Community Partnership to Enhance Care among Homeless Persons

An academic-community partnership between a Health Care for the Homeless (HCH) clinic and a school of pharmacy was created in 2005 to provide medication education and identify medication related problems. The urban community based HCH clinic in the Richmond, VA area provides primary health care to the homeless, uninsured and underinsured. The center also offers eye care, dental care, mental health and psychiatric care, substance abuse services, case management, laundry and shower facilities, and mail services at no charge to those in need. Pharmacist services are provided in the mental health and medical clinics. A satisfaction survey showed that the providers and staff (n = 13) in the clinic were very satisfied with the integration of pharmacist services. The quality and safety of medication use has improved as a result of the academic-community collaborative. Education and research initiatives have also resulted from the collaborative. This manuscript describes the implementation, outcomes and benefits of the partnership for both the HCH clinic and the school of pharmacy. Type:&nbsp;Clinical Experienc