Mechanisms to Evade the Phagocyte Respiratory Burst Arose by Convergent Evolution in Typhoidal Salmonella Serovars.

Typhoid fever caused by Salmonella enterica serovar (S.) Typhi differs in its clinical presentation from gastroenteritis caused by S. Typhimurium and other non-typhoidal Salmonella serovars. The different clinical presentations are attributed in part to the virulence-associated capsular polysaccharide (Vi antigen) of S. Typhi, which prevents phagocytes from triggering a respiratory burst by preventing antibody-mediated complement activation. Paradoxically, the Vi antigen is absent from S. Paratyphi A, which causes a disease that is indistinguishable from typhoid fever. Here, we show that evasion of the phagocyte respiratory burst by S. Paratyphi A required very long O antigen chains containing the O2 antigen to inhibit antibody binding. We conclude that the ability to avoid the phagocyte respiratory burst is a property distinguishing typhoidal from non-typhoidal Salmonella serovars that was acquired by S. Typhi and S. Paratyphi A independently through convergent evolution

Fostering Teacher-Student Relationships: A Case Study Connecting Middle School Teachers, Authentic Local History, and Empathetic Competence

TThis co-authored qualitative case study explores the challenge of teachers connecting with their students at the middle school level, especially when White teachers serve predominantly African-American students in large urban metropolitan areas like St. Louis, Missouri. While research has established the need for teachers to better understand the background experiences of their students, more research is needed to explore the value of place-based professional development in promoting more effective teacher-student relationships (TSRs). Using a psychological theory known as Relational-Cultural Theory (RCT), we sought to examine the following research questions while also applying this theory to the field of education: What insights does RCT offer as teachers engage in challenging local history? How does a teacher’s knowledge and awareness of a student’s neighborhood of origin influence the teacher-student relationship? What impact does an immersive experience in local history have toward increasing teacher’s empathetic competence? This case study examined the impact of a place-based professional development experience, i.e., a two-hour bus tour offered by the Missouri History Museum that explores St. Louis\u27 history of racial segregation and urban development, for middle school teachers at a small charter school in urban St. Louis. Through a series of in-depth interviews, classroom observations, and a focus group interview, data were collected to further study this phenomenon. We used reflexive thematic analysis (Terry & Hayfield, 2021) to derive themes and overall patterns of meaning. The study yielded the following findings: Teachers want better connections to their students. They also see how local history and knowledge of place can help strengthen the teacher-student relationship by building reciprocity and shared knowledge. Teachers can use local history as an entry point or pathway to building a relationship with students and families. Teachers see the value of adding local history to their professional development experiences, and advocate for student learning opportunities that incorporate authentic local history

Direct Amortized Likelihood Ratio Estimation

We introduce a new amortized likelihood ratio estimator for likelihood-free simulation-based inference (SBI). Our estimator is simple to train and estimates the likelihood ratio using a single forward pass of the neural estimator. Our approach directly computes the likelihood ratio between two competing parameter sets which is different from the previous approach of comparing two neural network output values. We refer to our model as the direct neural ratio estimator (DNRE). As part of introducing the DNRE, we derive a corresponding Monte Carlo estimate of the posterior. We benchmark our new ratio estimator and compare to previous ratio estimators in the literature. We show that our new ratio estimator often outperforms these previous approaches. As a further contribution, we introduce a new derivative estimator for likelihood ratio estimators that enables us to compare likelihood-free Hamiltonian Monte Carlo (HMC) with random-walk Metropolis-Hastings (MH). We show that HMC is equally competitive, which has not been previously shown. Finally, we include a novel real-world application of SBI by using our neural ratio estimator to design a quadcopter. Code is available at https://github.com/SRI-CSL/dnre.Comment: 12 Pages, 10 Figures, GitHub: https://github.com/SRI-CSL/dnr

Polysaccharide Processing and Presentation by the MHCII Pathway

AbstractThe adaptive immune system functions through the combined action of antigen-presenting cells (APCs) and T cells. Specifically, class I major histocompatibility complex antigen presentation to CD8+ T cells is limited to proteosome-generated peptides from intracellular pathogens while the class II (MHCII) endocytic pathway presents only proteolytic peptides from extracellular pathogens to CD4+ T cells. Carbohydrates have been thought to stimulate immune responses independently of T cells; however, zwitterionic polysaccharides (ZPSs) from the capsules of some bacteria can activate CD4+ T cells. Here we show that ZPSs are processed to low molecular weight carbohydrates by a nitric oxide-mediated mechanism and presented to T cells through the MHCII endocytic pathway. Furthermore, these carbohydrates bind to MHCII inside APCs for presentation to T cells. Our observations begin to elucidate the mechanisms by which some carbohydrates induce important immunologic responses through T cell activation, suggesting a fundamental shift in the MHCII presentation paradigm

Accuracy and reproducibility of coral Sr/Ca SIMS timeseries in modern and fossil corals

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Sayani, H., Cobb, K., Monteleone, B., & Bridges, H. Accuracy and reproducibility of coral Sr/Ca SIMS timeseries in modern and fossil corals. Geochemistry, Geophysics, Geosystems, 23(9), (2022): e2021GC010068, https://doi.org/10.1029/2021gc010068.Coral strontium-to-calcium ratios (Sr/Ca) provide quantitative estimates of past sea surface temperatures (SST) that allow for the reconstruction of changes in the mean state and climate variations, such as the El Nino-Southern Oscillation, through time. However, coral Sr/Ca ratios are highly susceptible to diagenesis, which can impart artifacts of 1–2°C that are typically on par with the tropical climate signals of interest. Microscale sampling via Secondary Ion Mass Spectrometry (SIMS) for the sampling of primary skeletal material in altered fossil corals, providing much-needed checks on fossil coral Sr/Ca-based paleotemperature estimates. In this study, we employ a set modern and fossil corals from Palmyra Atoll, in the central tropical Pacific, to quantify the accuracy and reproducibility of SIMS Sr/Ca analyses relative to bulk Sr/Ca analyses. In three overlapping modern coral samples, we reproduce bulk Sr/Ca estimates within ±0.3% (1σ). We demonstrate high fidelity between 3-month smoothed SIMS coral Sr/Ca timeseries and SST (R = −0.5 to −0.8; p < 0.5). For lightly-altered sections of a young fossil coral from the early-20th century, SIMS Sr/Ca timeseries reproduce bulk Sr/Ca timeseries, in line with our results from modern corals. Across a moderately-altered section of the same fossil coral, where diagenesis yields bulk Sr/Ca estimates that are 0.6 mmol too high (roughly equivalent to −6°C artifacts in SST), SIMS Sr/Ca timeseries track instrumental SST timeseries. We conclude that 3–4 SIMS analyses per month of coral growth can provide a much-needed quantitative check on the accuracy of fossil coral Sr/Ca-derived estimates of paleotemperature, even in moderately altered samples.We'd also like to thank Yolande Berta and Georgia Tech's Center for Nanostructure Characterization for providing access to their SEM facilities, and the Khaled bin Sultan Living Ocean Foundation and The Nature Conservancy for financial and logistical support for field excursions to Palmyra. Funding for this work was provided by the National Science Foundation (Award Numbers 1502832 and 2002458 to K.M.C) and the National Oceanic and Atmospheric Administration (Award Number: NA11OAR4310165 to K.M.C)

The Dillow’s Ridge Site and the Production of Mill Creek Chert Tools

The Dillow\u27s Ridge site (11 U635) is a small Mississippian village situated on an unplowed hilltop near the largest known Mill Creek chert quarry in Union County, Illinois. The site was both a permanent residential settlement and a major workshop where Mill Creek chert tools were produced for nonlocal use. Radiocarbon dates document the occupation from the late 1200s A.D. to A.D. 1450 or 1500. The production debris and rejects indicate that the major “export products were hoes and Ramey knives. Although the quantity of lithic debris on the site is very impressive, estimates of annual production of large biface implements are in the hundreds per year and not thousands. This level of production was easily attained by part-time specialists within a small community without major distortion of normal domestic and food-getting activities. Production and trade of these implements was also not a source of significant prestige or wealth for the producers

Disseminated Histoplasmosis in a Patient with Advanced HIV Disease—Lessons Learnt from Bangladesh

Histoplasmosis is a systemic fungal disease, also known as Darling's disease, caused by the dimorphic fungus Histoplasma capsulatum. It is usually self-limiting or localized in immunecompetent individuals whereas in patients with acquired immune deficiency syndrome (AIDS), it occurs in the disseminated form in 95% of cases. Although histoplasmosis predominates in the Americas (United States and Latin America, including Brazil) as an important infection among AIDS patients, it is not common in Bangladesh. In contrast, tuberculosis is extremely common in Bangladesh, with an estimated prevalence of 387 per 100,000 people. Here, a confirmed case of disseminated histoplasmosis is reported in Bangladesh in a known HIV-positive patient, which was initially suspected to be extrapulmonary tuberculosis