Membrane-anchored HDCR nanowires drive hydrogen-powered CO2 fixation.

Filamentous enzymes have been found in all domains of life, but the advantage of filamentation is often elusive1. Some anaerobic, autotrophic bacteria have an unusual filamentous enzyme for CO2 fixation-hydrogen-dependent CO2 reductase (HDCR)2,3-which directly converts H2 and CO2 into formic acid. HDCR reduces CO2 with a higher activity than any other known biological or chemical catalyst4,5, and it has therefore gained considerable interest in two areas of global relevance: hydrogen storage and combating climate change by capturing atmospheric CO2. However, the mechanistic basis of the high catalytic turnover rate of HDCR has remained unknown. Here we use cryo-electron microscopy to reveal the structure of a short HDCR filament from the acetogenic bacterium Thermoanaerobacter kivui. The minimum repeating unit is a hexamer that consists of a formate dehydrogenase (FdhF) and two hydrogenases (HydA2) bound around a central core of hydrogenase Fe-S subunits, one HycB3 and two HycB4. These small bacterial polyferredoxin-like proteins oligomerize through their C-terminal helices to form the backbone of the filament. By combining structure-directed mutagenesis with enzymatic analysis, we show that filamentation and rapid electron transfer through the filament enhance the activity of HDCR. To investigate the structure of HDCR in situ, we imaged T. kivui cells with cryo-electron tomography and found that HDCR filaments bundle into large ring-shaped superstructures attached to the plasma membrane. This supramolecular organization may further enhance the stability and connectivity of HDCR to form a specialized metabolic subcompartment within the cell.

The ABC exporter IrtAB imports and reduces mycobacterial siderophores.

Intracellular replication of the deadly pathogen Mycobacterium tuberculosis relies on the production of small organic molecules called siderophores that scavenge iron from host proteins1. M. tuberculosis produces two classes of siderophore, lipid-bound mycobactin and water-soluble carboxymycobactin2,3. Functional studies have revealed that iron-loaded carboxymycobactin is imported into the cytoplasm by the ATP binding cassette (ABC) transporter IrtAB4, which features an additional cytoplasmic siderophore interaction domain5. However, the predicted ABC exporter fold of IrtAB is seemingly contradictory to its import function. Here we show that membrane-reconstituted IrtAB is sufficient to import mycobactins, which are then reduced by the siderophore interaction domain to facilitate iron release. Structure determination by X-ray crystallography and cryo-electron microscopy not only confirms that IrtAB has an ABC exporter fold, but also reveals structural peculiarities at the transmembrane region of IrtAB that result in a partially collapsed inward-facing substrate-binding cavity. The siderophore interaction domain is positioned in close proximity to the inner membrane leaflet, enabling the reduction of membrane-inserted mycobactin. Enzymatic ATPase activity and in vivo growth assays show that IrtAB has a preference for mycobactin over carboxymycobactin as its substrate. Our study provides insights into an unusual ABC exporter that evolved as highly specialized siderophore-import machinery in mycobacteria.

IL-7 receptor signaling drives human B-cell progenitor differentiation and expansion.

Although absence of interleukin-7 (IL-7) signaling completely abrogates T and B lymphopoiesis in mice, patients with severe combined immunodeficiency caused by mutations in the IL-7 receptor α chain (IL-7Rα) still generate peripheral blood B cells. Consequently, human B lymphopoiesis has been thought to be independent of IL-7 signaling. Using flow cytometric analysis and single-cell RNA sequencing of bone marrow samples from healthy controls and patients who are IL-7Rα deficient, in combination with in vitro modeling of human B-cell differentiation, we demonstrate that IL-7R signaling plays a crucial role in human B lymphopoiesis. IL-7 drives proliferation and expansion of early B-cell progenitors but not of pre-BII large cells and has a limited role in the prevention of cell death. Furthermore, IL-7 guides cell fate decisions by enhancing the expression of BACH2, EBF1, and PAX5, which jointly orchestrate the specification and commitment of early B-cell progenitors. In line with this observation, early B-cell progenitors of patients with IL-7Rα deficiency still expressed myeloid-specific genes. Collectively, our results unveil a previously unknown role for IL-7 signaling in promoting the B-lymphoid fate and expanding early human B-cell progenitors while defining important differences between mice and humans. Our results have implications for hematopoietic stem cell transplantation strategies in patients with T- B+ severe combined immunodeficiency and provide insights into the role of IL-7R signaling in leukemogenesis.

Structural and functional characterization of MrpR, the master repressor of the Bacillus subtilis prophage SPß.

Prophages control their lifestyle to either be maintained within the host genome or enter the lytic cycle. Bacillus subtilis contains the SPß prophage whose lysogenic state depends on the MrpR (YopR) protein, a key component of the lysis-lysogeny decision system. Using a historic B. subtilis strain harboring the heat-sensitive SPß c2 mutant, we demonstrate that the lytic cycle of SPß c2 can be induced by heat due to a single nucleotide exchange in the mrpR gene, rendering the encoded MrpRG136E protein temperature-sensitive. Structural characterization revealed that MrpR is a DNA-binding protein resembling the overall fold of tyrosine recombinases. MrpR has lost its recombinase function and the G136E exchange impairs its higher-order structure and DNA binding activity. Genome-wide profiling of MrpR binding revealed its association with the previously identified SPbeta repeated element (SPBRE) in the SPß genome. MrpR functions as a master repressor of SPß that binds to this conserved element to maintain lysogeny. The heat-inducible excision of the SPß c2 mutant remains reliant on the serine recombinase SprA. A suppressor mutant analysis identified a previously unknown component of the lysis-lysogeny management system that is crucial for the induction of the lytic cycle of SPß.

Control of asparagine homeostasis in Bacillus subtilis: identification of promiscuous amino acid importers and exporters.

The Gram-positive model bacterium B. subtilis is able to import all proteinogenic amino acids from the environment as well as to synthesize them. However, the players involved in the acquisition of asparagine have not yet been identified for this bacterium. In this work, we used d-asparagine as a toxic analog of l-asparagine to identify asparagine transporters. This revealed that d- but not l-asparagine is taken up by the malate/lactate antiporter MleN. Specific strains that are sensitive to the presence of l-asparagine due to the lack of the second messenger cyclic di-AMP or due to the intracellular accumulation of this amino acid were used to isolate and characterize suppressor mutants that were resistant to the presence of otherwise growth-inhibiting concentrations of l-asparagine. These screens identified the broad-spectrum amino acid importers AimA and BcaP as responsible for the acquisition of l-asparagine. The amino acid exporter AzlCD allows detoxification of l-asparagine in addition to 4-azaleucine and histidine. This work supports the idea that amino acids are often transported by promiscuous importers and exporters. However, our work also shows that even stereo-enantiomeric amino acids do not necessarily use the same transport systems.IMPORTANCETransport of amino acid is a poorly studied function in many bacteria, including the model organism Bacillus subtilis. The identification of transporters is hampered by the redundancy of transport systems for most amino acids as well as by the poor specificity of the transporters. Here, we apply several strategies to use the growth-inhibitive effect of many amino acids under defined conditions to isolate suppressor mutants that exhibit either reduced uptake or enhanced export of asparagine, resulting in the identification of uptake and export systems for l-asparagine. The approaches used here may be useful for the identification of transporters for other amino acids both in B. subtilis and in other bacteria.

Multiple prenatal exposures and acute-care clinical encounters for asthma among children born to mothers living near a Superfund site.

Prenatal exposures are associated with childhood asthma, and risk may increase with simultaneous exposures. Pregnant women living in lower-income communities tend to have elevated exposures to a range of potential asthma risk factors, which may interact in complex ways. We examined the association between prenatal exposures and the risk of childhood acute-care clinical encounters for asthma (hospitalizations, emergency department visits, observational stays) using conditional logistic regression with a multivariable smoothing term to model the interaction between continuous variables, adjusted for maternal characteristics and stratified by sex. All births near the New Bedford Harbor (NBH) Superfund site (2000-2006) in New Bedford, Massachusetts, were followed through 2011 using the Massachusetts Pregnancy to Early Life Longitudinal (PELL) Data System to identify children aged 5-11 years with acute-care clinical asthma encounters (265 cases among 7787 children with follow-up). Hazard ratios (HRs) were higher for children living closer to the NBH site with higher umbilical cord blood lead levels than in children living further away from the NBH site with lower lead levels (P <.001). HRs were higher for girls (HR = 4.17; 95% CI, 3.60-4.82) than for boys (HR = 1.72; 95% CI, 1.46-2.02). Our results suggest that prenatal lead exposure in combination with residential proximity to the NBH Superfund site is associated with childhood asthma acute-care clinical encounters. This article is part of a Special Collection on Environmental Epidemiology.

Caregiver-reported quality of communication in pancreatic and periampullary cancer.

BACKGROUND: Communication between caregivers and clinical team members is critical for transitional care, but its quality and potential impact on outcomes are not well understood. This study reports on caregiver-reported quality of communication with clinical team members in the postpancreatectomy period and examines associations of these reports with patient and caregiver outcomes. METHODS: Caregivers of patients with pancreatic and periampullary malignancies who had undergone pancreatectomy were surveyed. Instrument measures assessed care experiences using the Caregiver Perceptions About Communication with Clinical Team Members (CAPACITY) instrument. The instrument has two main subscales: communication, assessing the extent to which providers helped caregivers comprehend details of clinical visits, and capacity, defined as the extent to which providers assessed whether caregivers were able to care for patients. RESULTS: Of 265 caregivers who were approached, 240 (90.6%) enrolled in the study. The mean communication and capacity subscale scores were 2.7 ± 0.6 and 1.5 ± 0.6, respectively (range, 0-4 [higher = better]). Communication subscale scores were lower among caregivers of patients who experienced (vs. those who did not experience) a 30-day readmission (2.6 ± 0.5 vs. 2.8 ± 0.6, respectively; p = .047). Capacity subscale scores were inversely associated with restriction in patient daily activities (a 0.04 decrement in the capacity score for every 1 point in daily activity restriction; p = .008). CONCLUSIONS: After pancreatectomy, patients with pancreatic and periampullary cancer whose caregivers reported worse communication with care providers were more likely to experience readmission. Caregivers of patients with greater daily activity restrictions were less likely to report being asked about the caregiver's skill and capacity by clinicians. PLAIN LANGUAGE SUMMARY: This prospective study used a validated survey instrument and reports on the quality of communication between health care providers and caregivers as reported by caregivers of patients with pancreatic and periampullary cancer after pancreatectomy. In an analysis of 240 caregivers enrolled in the study, lower communication scores (the extent to which providers helped caregivers understand clinical details) were associated with higher odds of 30-day patient readmission to the hospital. In addition, lower capacity scores (the extent to which providers assessed caregivers' ability to care for patients) were associated with greater impairment in caregivers. The strikingly low communication quality and capacity assessment scores suggest substantial room for improvement, with the potential to improve both caregiver and patient outcomes.

Predictors of Financial Toxicity Risk Among Patients Undergoing Cytoreductive Surgery with Hyperthermic Intraperitoneal Chemotherapy (CRS-HIPEC).

BACKGROUND: Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is the preferred treatment for select patients with peritoneal malignancies. However, the procedure is resource intensive and costly. This study aimed to determine the risk of financial toxicity for patients undergoing CRS-HIPEC. PATIENTS AND METHODS: We performed a retrospective cohort study of patients undergoing CRS-HIPEC at a single institution from 2016 to 2022. We utilized insurance status, out-of-pocket expenditures, and estimated post-subsistence income to determine risk of financial toxicity. A multivariable logistic regression was used to determine risk factors for financial toxicity. RESULTS: Our final study cohort consisted of 163 patients. Average age was 58 [standard deviation 10] years, and 52.8% (n = 86) were male. A total of 52 patients (31.9%) were at risk of financial toxicity. A total of 36 patients (22.1%) were from the lower income quartiles (first or second) and 127 patients (77.9%) were from the higher income quartiles (third or fourth). A total of 47 patients (29%) were insured by Medicare, and 116 patients (71%) had private insurance. The median out-of-pocket expenditure across the study cohort was $3500, with a median of $5000 ($3341-$7350) for the at-risk group and $3341 ($2500-$4022) for the not at-risk group (p < 0.001). Risk factors for financial toxicity included high out-of-pocket expenditures and a lower income quartile. CONCLUSIONS: An estimated one-third of patients undergoing CRS-HIPEC at our institution were at risk for financial toxicity. Several preoperative factors were associated with an increased risk and could be utilized to identify patients who might benefit from interventions.

Adoption of an Enhanced Recovery After Surgery Protocol Increases Cost of Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy and Does not Improve Outcomes.

BACKGROUND: Enhanced recovery after surgery (ERAS) protocols have been shown to reduce length of stay (LOS) and complications. The impact of ERAS protocols on the cost of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) has not been studied. PATIENTS AND METHODS: We performed a retrospective cohort analysis of patients undergoing CRS-HIPEC from 2016-2022 at a single quaternary center. Propensity score matching was used to create pre-and post-ERAS cohorts. Cost, overall and serious complications, and intensive care unit (ICU) length of stay (LOS) between the two cohorts were compared using the Mann-Whitney U-test for continuous variables and χ2 test for categorical variables. RESULTS: Our final matched cohort consisted of 100 patients, with 50 patients in both the pre- and post-ERAS groups. After adjusting for patient complexity and inflation, the median total cost [$75,932 ($67,166-102,645) versus $92,992 ($80,720-116,710), p = 0.02] and operating room cost [$26,817 ($23,378-33,121) versus $34,434 ($28,085-$41,379), p < 0.001] were significantly higher in the post-ERAS cohort. Overall morbidity (n = 22, 44% versus n = 17, 34%, p = 0.40) and ICU length of stay [2 days (IQR 1-3) versus 2 days (IQR 1-4), p = 0.70] were similar between the two cohorts. A total cost increase of $22,393 [SE $13,047, 95% CI (-$3178 to $47,965), p = 0.086] was estimated after implementation of ERAS, with operating room cost significantly contributing to this increase [$8419, SE $1628, 95% CI ($5228-11,609), p < 0.001]. CONCLUSIONS: CRS-HIPEC ERAS protocols were associated with higher total costs due to increased operating room costs at a single institution. There was no significant difference in ICU LOS and complications after the implementation of the ERAS protocol.

Intra- and Interpatient Drug Response Heterogeneity Exist in Patients Undergoing Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Nongynecologic Cancers.

BACKGROUND: Select patients with peritoneal metastases are treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). We assayed for intra- and interpatient drug response heterogeneity through testing of patient-derived tumor organoids (PDTOs). METHODS: PDTOs were generated from CRS/HIPEC patients from December 2021 to September 2022 and subjected to an in vitro HIPEC drug screen. Drug response was assessed with a cell viability assay and cleaved caspase-3 staining. RESULTS: A total of 31 patients were consented for tissue collection. Viable tissue was harvested from 23, and PDTO generation was successful in 13 (56%). PDTOs were analyzed from six appendiceal, three colorectal, two small bowel, one gastric, and one adrenal tumor. Drug screen results were generated in as few as 7 days (62%), with an average time of 12 days. Most patients received mitomycin-C (MMC) intraoperatively (n = 9); however, in only three cases was this agent considered the optimal choice in vitro. Three sets of PDTOs were resistant (defined as > 50% PDTO viability) to all agents tested and two were pan-sensitive (defined as 3 or more agents with < 50% PDTO viability). In three patients, organoids were generated from multiple metastatic sites and intrapatient drug response heterogeneity was observed. CONCLUSIONS: Both intra- and interpatient drug response heterogeneity exist in patients undergoing CRS/HIPEC for nongynecologic abdominal cancers. Caution must be used when interpreting patient response to chemotherapeutic agents based on a single site of testing in those with metastatic disease.

Preoperative CA 19-9 Predicts Disease Progression in Colorectal Peritoneal Metastases Treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy: An Analysis from the US HIPEC Collaborative.

INTRODUCTION: Patients with colorectal peritoneal metastases (CRPM) are increasingly treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). Unfortunately, data identifying preoperative risk factors for poor oncologic outcomes after this procedure are limited. We aimed to determine the prognostic value of preoperative CEA, CA 125, and CA 19-9 on disease progression after CRS/HIPEC. METHODS: Patients with CRPM treated with curative intent CRS/HIPEC from 12 participating sites in the United States from 2000 to 2017 were identified. Progression-free survival (PFS), defined as disease progression or recurrence, was the primary outcome. RESULTS: In 279 patients who met inclusion criteria, the rate of disease progression was 63.8%, with a median PFS of 11 months (interquartile range [IQR] 5-20). Elevated CA 19-9 was associated with dismal PFS at 2 years (8.9% elevated vs. 30% not elevated, p < 0.01). In 113 patients who underwent upfront CRS/HIPEC, CA 19-9 emerged as the sole tumor marker independently predictive of worse PFS (hazard ratio [HR] 2.88, p = 0.048). In the subgroup of patients who had received neoadjuvant therapy (NAT), no variable was independently predictive of PFS. CA 19-9 levels over 37 U/ml were highly specific for accelerated disease progression after CRS/HIPEC. Lastly, there was no association between PFS and elevated CEA or CA 125. CONCLUSIONS: Elevated CA 19-9 is associated with decreased PFS in patients with CRPM. While traditionally CEA is the main tumor marker assessed in colon cancer, we found that CA 19-9 may better inform preoperative risk stratification for poor oncologic outcomes in patients with CRPM. However, prospective studies are required to confirm this association.

Sarcopenia is associated with chemoradiotherapy discontinuation and reduced progression-free survival in glioblastoma patients.

PURPOSE: Sarcopenia may complicate treatment in cancer patients. Herein, we assessed whether sarcopenia measurements derived from radiation planning computed tomography (CT) were associated with complications and tumor progression during radiochemotherapy for glioblastoma. METHODS: Consecutive patients undergoing radiotherapy planning for glioblastoma between 2010 and 2021 were analyzed. Retrocervical muscle cross-sectional area (CSA) was measured via threshold-based semi-automated radiation planning CT analysis. Patients in the lowest sex-specific quartile of muscle measurements were defined as sarcopenic. We abstracted treatment characteristics and tumor progression from the medical records and performed uni- and multivariable time-to-event analyses. RESULTS: We included 363 patients in our cohort (41.6% female, median age 63 years, median time to progression 7.7 months). Sarcopenic patients were less likely to receive chemotherapy (p < 0.001) and more likely to be treated with hypofractionated radiotherapy (p = 0.005). Despite abbreviated treatment, they more often discontinued radiotherapy (p = 0.023) and were more frequently prescribed corticosteroids (p = 0.014). After treatment, they were more often transferred to inpatient palliative care treatment (p = 0.035). Finally, progression-free survival was substantially shorter in sarcopenic patients in univariable (median 5.1 vs. 8.4 months, p < 0.001) and multivariable modeling (hazard ratio 0.61 [confidence interval 0.46-0.81], p = 0.001). CONCLUSION: Sarcopenia is a strong risk factor for treatment discontinuation and reduced progression-free survival in glioblastoma patients. We propose that sarcopenic patients should receive intensified supportive care during radiotherapy and during follow-up as well as expedited access to palliative care.

Heat-induced hormesis in longevity is linked to heat-stress sensitivity across laboratory populations from diverse altitude of origin in Drosophila buzzatii.

Heat-induced hormesis in longevity is the increase in life span resulting from the previous exposure to a mild heat stress early in life. Here we examined heat-induced hormesis of Drosophila buzzatii in five mass-mating populations, which were derived from five wild populations along an elevation gradient from 202 to 1855 m above sea level in North-Western Argentina. Five day old flies were exposed to 37.5 °C for 90 min to induce hormesis and its possible variation across altitudinal populations. This heat treatment strongly extended longevity in lowland-derived flies from the most heat-resistant population only. Both heat-induced effects on longevity and heat-knockdown time (heat-stress sensitivity) were negatively correlated to altitude of population of origin. Hormesis was positively correlated to heat-knockdown time across populations. These results indicate that variation in heat-induced hormesis can not be considered as independent of heat-stress sensitivity (or heat-knockdown time) in populations of insects.

Primary Tumor Resection in Leiomyosarcoma Patients With Synchronous Isolated Lung Metastases: A National Cancer Database Study.

INTRODUCTION: Up to half of patients with leiomyosarcoma (LMS) present with distant metastases, most commonly in the lungs. Despite guidelines around managing metachronous oligometastatic disease, limited evidence exists for synchronous isolated lung metastases (SILMs). Our histology-specific study describes management patterns and outcomes for patients with LMS and SILM across disease sites. METHODS: We used the National Cancer Database to analyze patients with LMS of the retroperitoneum, extremity, trunk/chest/abdominal wall, and pelvis with SILM. Patients with extra-pulmonary metastases were excluded. We identified factors associated with primary tumor resection and receipt of metastasectomy. Outcomes included median, 1-year, and 5-year overall survival (OS) across treatment approaches using log-rank tests, Kaplan-Meier curves, and Cox proportional hazard models. RESULTS: We identified 629 LMS patients with SILM from 2004 to 2017. Patients were more likely to have resection of their primary tumor or lung metastases if treated at an academic center compared to a community cancer center. Five year OS for patients undergoing both primary tumor resection and metastasectomy was 20.9% versus 9.2% for primary tumor resection alone, and 2.6% for nonsurgical patients. Median OS for all-comers was 15.5 mo. Community treatment site, comorbidity score, and larger primary tumors were associated with worse survival. Chemotherapy, primary resection, and curative intent surgery predicted improved survival on multivariate Cox regression. CONCLUSIONS: An aggressive surgical approach to primary LMS with SILM was undertaken for select patients in our population and found to be associated with improved OS. This approach should be considered for suitable patients at high-volume centers.

Creating a Sustainable Foundation for IR Services and Training in Sub-Saharan Africa: 5-Year Update on the Road2IR Initiative.

PURPOSE: To evaluate the growth and quality of an interventional radiology (IR) training model designed for resource-constrained settings and implemented in Tanzania as well as its overall potential to increase access to minimally invasive procedures across the region. MATERIALS AND METHODS: IR training in Tanzania began in October 2018 through monthly deployment of visiting teaching teams for hands-on training combined with in-person and remote lectures. A competency-based 2-year Master of Science in IR curriculum was inaugurated at the nation's main teaching hospital in October 2019, with the first 2 classes graduating in 2021 and 2022. Procedural data, demographics, and clinical outcomes were collected and analyzed throughout the duration of this program. RESULTS: From October 2018 to July 2022, 1,595 procedures were performed in Tanzania: 1,236 nonvascular and 359 vascular, all with local fellows as primary interventional radiologists. Of these, 97.2% were technically successful, 95.2% were without adverse events, and 28.9% were performed independently by Tanzanian fellows and faculty with no difference in adverse event and technical success rates (P = .63 and P = .90, respectively), irrespective of procedural class. Ten IR physicians graduated from this program during the study period, followed by another 3 per year going forward. Partner training programs in Uganda and Rwanda mirroring this model commenced in 2023 and 2024, respectively. CONCLUSIONS: The reported training model offers a practical and effective solution to meet many of the challenges associated with the lack of access to IR in sub-Saharan Africa.

Morphology of nares associated with stereo-olfaction in baleen whales.

The sensory mechanisms used by baleen whales (Mysticeti) for locating ephemeral, dense prey patches in vast marine habitats are poorly understood. Baleen whales have a functional olfactory system with paired rather than single blowholes (nares), potentially enabling stereo-olfaction. Dimethyl sulfide (DMS) is an odorous gas emitted by phytoplankton in response to grazing by zooplankton. Some seabirds use DMS to locate prey, but this ability has not been demonstrated in whales. For 14 extant species of baleen whale, nares morphometrics (imagery from unoccupied aerial systems, UAS) was related to published trophic level indices using Bayesian phylogenetic mixed modelling. A significant negative relationship was found between nares width and whale trophic level (ß = -0.08, lower 95% CI = -0.13, upper 95% CI = -0.03), corresponding with a 39% increase in nares width from highest to lowest trophic level. Thus, species with nasal morphology best suited to stereo-olfaction are more zooplanktivorous. These findings provide evidence that some baleen whale species may be able to localize odorants e.g. DMS. Our results help direct future behavioural trials of olfaction in baleen whales, by highlighting the most appropriate species to study. This is a research priority, given the potential for DMS-mediated plastic ingestion by whales.

Acquired resistance to IDH inhibition through trans or cis dimer-interface mutations.

Somatic mutations in the isocitrate dehydrogenase 2 gene (IDH2) contribute to the pathogenesis of acute myeloid leukaemia (AML) through the production of the oncometabolite 2-hydroxyglutarate (2HG)1-8. Enasidenib (AG-221) is an allosteric inhibitor that binds to the IDH2 dimer interface and blocks the production of 2HG by IDH2 mutants9,10. In a phase I/II clinical trial, enasidenib inhibited the production of 2HG and induced clinical responses in relapsed or refractory IDH2-mutant AML11. Here we describe two patients with IDH2-mutant AML who had a clinical response to enasidenib followed by clinical resistance, disease progression, and a recurrent increase in circulating levels of 2HG. We show that therapeutic resistance is associated with the emergence of second-site IDH2 mutations in trans, such that the resistance mutations occurred in the IDH2 allele without the neomorphic R140Q mutation. The in trans mutations occurred at glutamine 316 (Q316E) and isoleucine 319 (I319M), which are at the interface where enasidenib binds to the IDH2 dimer. The expression of either of these mutant disease alleles alone did not induce the production of 2HG; however, the expression of the Q316E or I319M mutation together with the R140Q mutation in trans allowed 2HG production that was resistant to inhibition by enasidenib. Biochemical studies predicted that resistance to allosteric IDH inhibitors could also occur via IDH dimer-interface mutations in cis, which was confirmed in a patient with acquired resistance to the IDH1 inhibitor ivosidenib (AG-120). Our observations uncover a mechanism of acquired resistance to a targeted therapy and underscore the importance of 2HG production in the pathogenesis of IDH-mutant malignancies.

Assessing interventional radiology specialty knowledge and perception amongst Tanzanian medical students before and after exposure to an immersive curriculum.

AIMS: This study aims to assess the impact that delivering an introductory interventional radiology (IR) lecture series has on the knowledge and perception of the specialty among medical students in a resource-limited setting with, until recently, no IR presence. MATERIALS AND METHODS: An introductory four-hour lecture series in IR was delivered to third-year medical students in Tanzania. Prior to and following the lecture series, participants completed a 27-item paper-based survey assessing their knowledge and perception of the specialty. RESULTS: Out of a class of 213, the pre- and post-lecture survey was returned by 148 (69.5%) and 151 (70.9%) respondents, respectively. 94.5% of respondents indicated that they were aware of IR as a specialty. Among respondents, 97.3% expressed interest in having IR lectures integrated into their curriculum, compared to 29.0% that reported having any prior IR training. 27.3% believed their knowledge in IR compared to other specialties was either "good" or "excellent", which improved to 43.3% (p<0.001). Identification that IR physicians consult patients directly, have outpatient clinics, have inpatient beds, and do rounds improved from 55.4% to 81.1% (p<0.001), 49.7% to 60.3% (p=0.066), 48.3% to 66.7% (p=0.001), and 52.0% to 66.2% (p=0.013), respectively. CONCLUSION: By introducing short lectures on IR-relevant topics, knowledge and perception of IR improved among Tanzanian medical students. Early education and exposure to IR should be prioritized to promote the continued growth of the specialty in this setting.

Evaluating COVID-19 Risk to Essential Workers by Occupational Group: A Case Study in Massachusetts.

Occupational exposure to SARS-CoV-2 varies by profession, but "essential workers" are often considered in aggregate in COVID-19 models. This aggregation complicates efforts to understand risks to specific types of workers or industries and target interventions, specifically towards non-healthcare workers. We used census tract-resolution American Community Survey data to develop novel essential worker categories among the occupations designated as COVID-19 Essential Services in Massachusetts. Census tract-resolution COVID-19 cases and deaths were provided by the Massachusetts Department of Public Health. We evaluated the association between essential worker categories and cases and deaths over two phases of the pandemic from March 2020 to February 2021 using adjusted mixed-effects negative binomial regression, controlling for other sociodemographic risk factors. We observed elevated COVID-19 case incidence in census tracts in the highest tertile of workers in construction/transportation/buildings maintenance (Phase 1: IRR 1.32 [95% CI 1.22, 1.42]; Phase 2: IRR: 1.19 [1.13, 1.25]), production (Phase 1: IRR: 1.23 [1.15, 1.33]; Phase 2: 1.18 [1.12, 1.24]), and public-facing sales and services occupations (Phase 1: IRR: 1.14 [1.07, 1.21]; Phase 2: IRR: 1.10 [1.06, 1.15]). We found reduced case incidence associated with greater percentage of essential workers able to work from home (Phase 1: IRR: 0.85 [0.78, 0.94]; Phase 2: IRR: 0.83 [0.77, 0.88]). Similar trends exist in the associations between essential worker categories and deaths, though attenuated. Estimating industry-specific risk for essential workers is important in targeting interventions for COVID-19 and other diseases and our categories provide a reproducible and straightforward way to support such efforts.

Surgeon-reported Factors Influencing Adoption of Quality Standards for Goal-concordant Care in Patients With Advanced Cancer: A Qualitative Study.

OBJECTIVE: This study explored surgical oncologists' perspectives on factors influencing adoption of quality standards in patients with advanced cancer. BACKGROUND: The American College of Surgeons Geriatric Surgery Verification Program includes communication standards designed to facilitate goal-concordant care, yet little is known about how surgeons believe these standards align with clinical practice. METHODS: Semistructured video-based interviews were conducted from November 2020 to January 2021 with academic surgical oncologists purposively sampled based on demographics, region, palliative care certification, and years in practice. Interviews addressed: (1) adherence to standards documenting care preferences for life-sustaining treatment, surrogate decision-maker, and goals of surgery; and (2) factors influencing their adoption into practice. Interviews were audio-recorded, transcribed, qualitatively analyzed, and conducted until thematic saturation was reached. RESULTS: Twenty-six surgeons participated (57.7% male, 8.5 mean years in practice, 19.2% palliative care board-certified). Surgeons reported low adherence to documenting care preferences and surrogate decision-maker and high adherence to discussing, but not documenting, goals of surgery. Participants held conflicting views about the relevance of care preferences to preoperative conversations and surrogate decision-maker documentation by the surgeon and questioned the direct connection between documentation of quality standards and higher value patient care. Key themes regarding factors influencing adoption of quality standards included organizational culture, workflow, and multidisciplinary collaboration. CONCLUSIONS: Although surgeons routinely discuss goals of surgery, documentation is inconsistent; care preferences and surrogate decision-makers are rarely discussed or documented. Adherence to these standards would be facilitated by multidisciplinary collaboration, institutional standardization, and evidence linking standards to higher value care.