Comparison of Joint Compression and Pull- Out Strength of 6.5-mm Self-Drilling Screws With Headed and Headless in Subtalar Arthrodesis: A Pilot Study

Background: In patients with degenerative osteoarthritis of the subtalar joint, surgical treatment can include subtalar arthrodesis. Notably, mechanical factors such as compression and pull-out strength contribute to successful union, which can be achieved through use of headed or headless cannulate screws. The purpose of this study was to compare the resultant joint compressive force and pull-out strength between use of a headless 6.5-mm self-drilling cannulated compression screw and a more traditional headed 6.5- mm self-drilling cannulated compression screw. Methods: This study used the calcaneus and talus from six paired fresh frozen specimens. The soft tissues were stripped and the joint was separated. Fujifilm Prescale Compression Paper (Minato, Tokyo, Japan) was placed in the subtalar joint, and both the talus and calcaneus were fixed with either traditional headed or a headless cannulated screw. Pull-out strength was measured by fixing the fused subtalar joints to a servohydraulic activator and measuring peak load at failure in distraction. Imaging analysis of the compression paper determined peak compression across the joint. Results: The resultant joint compressive force and pull-out strength were not statistically different between use of headed and headless cannulated compression screws (P = 0.30 and P = 0.67, respectively). Conclusions: In a small sample, use of headless cannulated compression screws offered equivalent joint compression as that of a headed screw in subtalar arthrodesis and showed equivalent resistance to pullout force

Biomechanical Strength and Bulk Comparisons Between the Open-Book Technique and the Pulvertaft Method for Peroneal Tendon Transfer: A Pilot Study

Background: The Pulvertaft method has classically been used for the transfer of various tendon injuries owing to its biomechanical strength; however, this method has been shown to be bulky. We describe the open-book technique, which can offer comparable structural integrity with a decreased bulk. The purpose of this study was to determine whether the openbook technique is biomechanically equivalent to the Pulvertaft method for treating peroneal tendon injuries. Methods: We evaluated five pairs of human cadaveric ankles. Within each pair, one specimen was randomly assigned to either the Pulvertaft or the open-book group. Using sharp dissection, the tendons were severed in a standardized method. Transfer was performed using one of the two randomly assigned techniques. The transferred peroneal tendons were stressed on a mechanical tensioning device until failure. Data were recorded and analysis was performed. Results: There was a statistically significant difference (P \u3c 0.001) between the thickness of the Pulvertaft method (7.6 mm) and open-book technique (5.7 mm). There was also a statistically significant difference in elongation, with the Pulvertaft undergoing more elongation at yield (9.7 mm vs 3.7 mm, respectively; P = 0.04). No statistical difference was detected in elongation at peak (P = 0.52), load at yield (P = 0.9), or peak load (P = 0.69). Conclusions: The open-book technique appears to be a viable biomechanical alternative to the Pulvertaft method for peroneal tendon transfer. The peak load, load at yield, and elongation at peak were biomechanically equivalent. The open-book technique was found to provide a significant decrease in thickness, which could prove advantageous when dealing with anatomical locations

Open Problems and Fundamental Limitations of Reinforcement Learning from Human Feedback

Reinforcement learning from human feedback (RLHF) is a technique for training AI systems to align with human goals. RLHF has emerged as the central method used to finetune state-of-the-art large language models (LLMs). Despite this popularity, there has been relatively little public work systematizing its flaws. In this paper, we (1) survey open problems and fundamental limitations of RLHF and related methods; (2) overview techniques to understand, improve, and complement RLHF in practice; and (3) propose auditing and disclosure standards to improve societal oversight of RLHF systems. Our work emphasizes the limitations of RLHF and highlights the importance of a multi-faceted approach to the development of safer AI systems

In-Orbit Performance of the GRACE Follow-on Laser Ranging Interferometer

The Laser Ranging Interferometer (LRI) instrument on the Gravity Recovery and Climate Experiment (GRACE) Follow-On mission has provided the first laser interferometric range measurements between remote spacecraft, separated by approximately 220 km. Autonomous controls that lock the laser frequency to a cavity reference and establish the 5 degrees of freedom two-way laser link between remote spacecraft succeeded on the first attempt. Active beam pointing based on differential wave front sensing compensates spacecraft attitude fluctuations. The LRI has operated continuously without breaks in phase tracking for more than 50 days, and has shown biased range measurements similar to the primary ranging instrument based on microwaves, but with much less noise at a level of 1 nm/Hz at Fourier frequencies above 100 mHz. © 2019 authors. Published by the American Physical Society

Variation in Survival and Gut Microbiome Composition of Hatchery-Grown Native Oysters at Various Locations within the Puget Sound.

The Olympia oyster (Ostrea lurida) of the Puget Sound suffered a dramatic population crash, but restoration efforts hope to revive this native species. One overlooked variable in the process of assessing ecosystem health is association of bacteria with marine organisms and the environments they occupy. Oyster microbiomes are known to differ significantly between species, tissue type, and the habitat in which they are found. The goals of this study were to determine the impact of field site and habitat on the oyster microbiome and to identify core oyster-associated bacteria in the Puget Sound. Olympia oysters from one parental family were deployed at four sites in the Puget Sound both inside and outside of eelgrass (Zostera marina) beds. Using 16S rRNA gene amplicon sequencing of the oyster gut, shell, and surrounding seawater and sediment, we demonstrate that gut-associated bacteria are distinct from the surrounding environment and vary by field site. Furthermore, regional differences in the gut microbiota are associated with the survival rates of oysters at each site after 2 months of field exposure. However, habitat type had no influence on microbiome diversity. Further work is needed to identify the specific bacterial dynamics that are associated with oyster physiology and survival rates. IMPORTANCE This is the first exploration of the microbial colonizers of the Olympia oyster, a native oyster species to the West Coast, which is a focus of restoration efforts. The patterns of differential microbial colonization by location reveal microscale characteristics of potential restoration sites which are not typically considered. These microbial dynamics can provide a more holistic perspective on the factors that may influence oyster performance

Immunostimulatory Defective Viral Genomes from Respiratory Syncytial Virus Promote a Strong Innate Antiviral Response during Infection in Mice and Humans

<div><p>Human respiratory syncytial virus (RSV) is a major cause of severe respiratory illness in children and susceptible adults. RSV blocks the development of the innate antiviral immune response and can grow to high titers in the respiratory tract. Here we demonstrate that immunostimulatory defective viral genomes (iDVGs) that are naturally generated during RSV replication are strong inducers of the innate antiviral response to RSV in mice and humans. In mice, RSV iDVGs stimulated the expression of antiviral genes, restricted viral replication, and prevented weight loss and lung inflammation. In human cells, the antiviral response to RSV iDVGs was dominated by the expression of IFN-λ1 over IFN-β and was driven by rapid intranuclear accumulation of the transcription factor IRF1. RSV iDVGs were detected in respiratory secretions of hospitalized patients, and their amount positively correlated with the level of expression of antiviral genes in the samples. Infection of explanted human lung tissue from different donors revealed that most humans can respond to RSV iDVGs and that the rate of accumulation of iDVGs during infection directly correlates with the quality of the antiviral response. Taken together, our data establish iDVGs as primary triggers of robust antiviral responses to RSV and provide the first evidence for an important biological role for naturally occurring iDVGs during a <i>paramyxovirus</i> infection in humans.</p></div

RSV iDVGs stimulate an IRF1/IFNL1-mediated antiviral response.

<p>A549 cells were infected with RSV-LD or RSV-HD at a moi of 1.5 TCID₅₀/cell. Expression of (A) RSV G and antiviral genes mRNA, and (B) protein level of IFNB1 and IFNL1/3 in the cultures supernatants at 24 h post infection (*p<0.05 by one way unpaired t-test). (C, D) Cells were lysed or fixed at 2, 6, 12, and 24 h post infection for western blot (WB) and IFA. (C) For WB, nuclear and cytosolic fractions were immunoblotted for IRF1, GAPDH, and Histone 3. (D) For IFA, cells were co-stained for IRF1 (green, left panel), RSV F + G proteins (red in merged panel), and nuclei (blue). (E) Quantification of nuclear IRF1 upon iDVGs stimulation at designated time points post RSV-HD infection based on IFA images. (F, G) D54 control cells and D54 cells overexpressing IRF1 (D54-IRF1) were infected with RSV-HD at a moi of 1.5 TCID₅₀/cell for 6 h. (F) IRF1 and IRF3 protein detected by WB from whole cell lysates. (G) Expression of RSV G and IFNL1 mRNA. (H, I) A549 cells were mock transfected (WT) or transfected with control siRNA (si-C), or IRF1 siRNA (si-1). After 40 h, the cells were mock infected or infected with RSV-HD at moi of 1.5 TCID₅₀/cell. (H) WB for IRF3 and IRF1 was performed to confirm specific knockdown of IRF1 protein. (I) Expression of RSV G and other antiviral genes at 10 h post infection. Gene expression is shown as copy number relative to a house keeping gene expression index determined from the expression of ACTB (β-actin) and GAPDH. All error bars indicate mean ± SEM of at least three independent experiments (*p<0.05, **p<0.01, ***p<0.001, ****p<0.0001 by two-way ANOVA with Bonferroni post hoc test).</p

Host-intrinsic factors determine the response to iDVGs in the human lung.

<p>(A) Images of precision cut lung slices from human lungs (hPCLS) infected for 24 h with 10⁶ RSV-GFP TCID₅₀/slice. Top: Overlay of bright field and fluorescence channels; Bottom: fluorescence channel alone. (B) Gene expression from hPCLS infected with 10⁷ TCID₅₀/slice of RSV-LD or HD for up to 5 days (n = 7–8, grey numbers indicate individual lung donor). Results show paired data, numbers correspond to different donors. (*p<0.05, **p<0.01 by one-tailed Wilcoxon matched-pairs signed rank test). (C) Ratio of gene expression in RSV-HD and RSV-LD infected tissue from different donors (P3-P9). Ratio>1: HD induced a higher gene expression than LD. (D) PCR for DVGs in hPCLS infected with 10⁶ TCID₅₀/slice of RSV-LD. (E) Gene expression from (D). Error bars indicate mean ± SEM of three slices from the same patient.</p

iDVGs associate with high expression of antiviral genes in respiratory secretions from patients infected with RSV.

<p>(A) Representative PCR results for gRSV and DVGs in human nasopharyngeal control samples infected with adenovirus (A1-A5) and samples infected with RSV (R1-R4). (B) Gene expression determined by RT-qPCR shown as copy number relative to house keeping genes (*p<0.05, **p<0.01, by two-tailed Mann Whitney test). (C) Samples were scored based on the intensity of the DVG amplicons (1–4, absent to highest intensity) and correlated with the level of expression of antiviral genes. (r = correlation coefficient, p<0.0001 for slope deviation from 0).</p

RSV DVGs prevent viral pathogenesis in vivo.

<p>(A) Hep2 cells were infected with RSV-LD or HD at a moi of 1.5 TCID₅₀/cell and DVGs were detected by PCR at the indicated times. Details of the PCR assay can be seen in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005122#ppat.1005122.s001" target="_blank">S1 Fig</a> and sequences of the amplicons labeled with a star can be found in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005122#ppat.1005122.s002" target="_blank">S2 Fig</a> Base pair size references are indicated in the gel. (B) Mice weight loss was monitored overtime. Error bars indicate standard deviation of data pooled from two independent experiments (n = 7–9 mice per group total; **p<0.01, ****p<0.0001 by two-way ANOVA with Bonferroni post hoc test. Variance was not significantly different between groups as per Bartlett’s test). (C) Representative H&E staining for lung sections from mock, RSV-LD, or RSV-HD-infected mice on day 2 post infection. Picture magnification: 10X; insert is a digital amplification. Red arrows indicate alveolar cellular infiltrate. (D) Pathology score for alveolar infiltration in the lung (n = 6 mice per group; **p<0.01, by two-tailed Mann Whitney test). (E) Differential counts from cytospins from mice bronchoalveolar lavage (BAL) on day 2 post infection (Mono: monocytes and macrophages, PMNs: polymorphonuclear cells; ***p<0.001 by two-way ANOVA with Bonferroni’s post hoc test, n = 5–8 mice per group). (F) Representative cytospin images (20X). (G) Representative flow cytometry plots from whole lung single cell suspensions on day 2 post infection. Plots are pre-gated in singlets, live, CD45⁺CD11b⁺ cells. (H) Quantification of different cell types in the lung of infected mice on day 2 post infection (****p<0.0001 by two-way ANOVA with Bonferroni’s post hoc test, n = 5–8 mice per group, Alv. Macs: alveolar macrophages). (I) Expression of pro-inflammatory genes in whole lung tissue on day 2, 5, and 8 post infection. (n = 3–5 mice per group, *p<0.05, **p<0.01 by one-way ANOVA with Bonferroni’s post hoc test).</p