Synovial Chondromatosis and Chondrosarcoma: A Diagnostic Dilemma

Purpose: The progression of synovial chondromatosis to chondrosarcoma is very rare. Distinction between these two entities may be difficult on histology alone, and should be based on clinical, radiographic and microscopic evidence. Immunohistochemical markers that would facilitate differentiation between synovial chondromatosis and chondrosarcoma are currently being investigated

Oxygen and animals in Earth history

Earth and Planetary Science

A Basin Redox Transect at the Dawn of Animal Life

Multiple eukaryotic clades make their first appearance in the fossil record between ~810 and 715 Ma. Molecular clock studies suggest that the origin of animal multicellularity may have been part of this broader eukaryotic radiation. Animals require oxygen to fuel their metabolism, and low oxygen levels have been hypothesized to account for the temporal lag between metazoan origins and the Cambrian radiation of large, ecologically diverse animals. Here, paleoredox conditions were investigated in the Fifteenmile Group, Ogilvie Mountains, Yukon, Canada, which hosts an 811 Ma ash horizon and spans the temporal window that captures the inferred origin and early evolution of animals. Iron-based redox proxies, redox-sensitive trace elements, organic carbon percentages and pyrite sulfur isotopes were analyzed in seven stratigraphic sections along two parallel basin transects. These data suggest that for this basin, oxygenated shelf waters overlay generally anoxic deeper waters. The anoxic water column was dominantly ferruginous, but brief periods of euxinia likely occurred. These oscillations coincide with changes in total organic carbon, suggesting euxinia was primarily driven by increased organic carbon loading. Overall, these data are consistent with proposed quantitative constraints on Proterozoic atmospheric oxygen being greater than 1% of modern levels, but less than present levels. Comparing these oxygen levels against the likely oxygen requirements of the earliest animals, both theoretical considerations and the ecology of modern oxygen-deficient settings suggest that the inferred oxygen levels in the mixed layer would not have been prohibitive to the presence of sponges, eumetazoans or bilaterians. Thus the evolution of the earliest animals was probably not limited by the low absolute oxygen levels that may have characterized Neoproterozoic oceans, although these inferred levels would constrain animals to very small sizes and low metabolic rates.Earth and Planetary SciencesOrganismic and Evolutionary Biolog

The Ecological Physiology of Earth's Second Oxygen Revolution

Living animals display a variety of morphological, physiological, and biochemical characters that enable them to live in low-oxygen environments. These features and the organisms that have evolved them are distributed in a regular pattern across dioxygen (O2) gradients associated with modern oxygen minimum zones. This distribution provides a template for interpreting the stratigraphic covariance between inferred Ediacaran-Cambrian oxygenation and early animal diversification. Although Cambrian oxygen must have reached 10--20% of modern levels, sufficient to support the animal diversity recorded by fossils, it may not have been much higher than this. Today’s levels may have been approached only later in the Paleozoic Era. Nonetheless, Ediacaran-Cambrian oxygenation may have pushed surface environments across the low, but critical, physiological thresholds required for large, active animals, especially carnivores. Continued focus on the quantification of the partial pressure of oxygen (pO2) in the Proterozoic will provide the definitive tests of oxygen-based coevolutionary hypotheses.Earth and Planetary SciencesOrganismic and Evolutionary Biolog

The effects of test-enhanced learning on long-term retention in AAN annual meeting courses.

OBJECTIVE: We measured the long-term retention of knowledge gained through selected American Academy of Neurology annual meeting courses and compared the effects of repeated quizzing (known as test-enhanced learning) and repeated studying on that retention. METHODS: Participants were recruited from 4 annual meeting courses. All participants took a pretest. This randomized, controlled trial utilized a within-subjects design in which each participant experienced 3 different postcourse activities with each activity performed on different material. Each key information point from the course was randomized in a counterbalanced fashion among participants to one of the 3 activities: repeated short-answer quizzing, repeated studying, and no further exposure to the materials. A final test covering all information points from the course was taken 5.5 months after the course. RESULTS: Thirty-five participants across the 4 courses completed the study. Average score on the pretest was 36%. Performance on the final test showed that repeated quizzing led to significantly greater long-term retention relative to both repeated studying (55% vs 46%; t[34] = 3.28, SEM = 0.03, p = 0.01, d = 0.49) and no further exposure (55% vs 44%; t[34] = 3.16, SEM = 0.03, p = 0.01, d = 0.58). Relative to the pretest baseline, repeated quizzing helped participants to retain almost twice as much of the knowledge acquired from the course compared to repeated studying or no further exposure. CONCLUSIONS: Whereas annual meeting continuing medical education (CME) courses lead to long-term gains in knowledge, when repeated quizzing is added, retention is significantly increased. CME planners may consider adding repeated quizzing to increase the impact of their courses

Oxygen, Ecology, and the Cambrian Radiation of Animals

The Proterozoic-Cambrian transition records the appearance of essentially all animal body plans (phyla), yet to date no single hypothesis adequately explains both the timing of the event and the evident increase in diversity and disparity. Ecological triggers focused on escalatory predator–prey “arms races” can explain the evolutionary pattern but not its timing, whereas environmental triggers, particularly ocean/atmosphere oxygenation, do the reverse. Using modern oxygen minimum zones as an analog for Proterozoic oceans, we explore the effect of low oxygen levels on the feeding ecology of polychaetes, the dominant macrofaunal animals in deep-sea sediments. Here we show that low oxygen is clearly linked to low proportions of carnivores in a community and low diversity of carnivorous taxa, whereas higher oxygen levels support more complex food webs. The recognition of a physiological control on carnivory therefore links environmental triggers and ecological drivers, providing an integrated explanation for both the pattern and timing of Cambrian animal radiation.Earth and Planetary SciencesOrganismic and Evolutionary Biolog

γδ T cells affect IL-4 production and B-cell tolerance

γδ T cells can influence specific antibody responses. Here, we report that mice deficient in individual γδ T-cell subsets have altered levels of serum antibodies, including all major subclasses, sometimes regardless of the presence of αβ T cells. One strain with a partial γδ deficiency that increases IgE antibodies also displayed increases in IL-4–producing T cells (both residual γδ T cells and αβ T cells) and in systemic IL-4 levels. Its B cells expressed IL-4–regulated inhibitory receptors (CD5, CD22, and CD32) at diminished levels, whereas IL-4–inducible IL-4 receptor α and MHCII were increased. They also showed signs of activation and spontaneously formed germinal centers. These mice displayed IgE-dependent features found in hyper-IgE syndrome and developed antichromatin, antinuclear, and anticytoplasmic autoantibodies. In contrast, mice deficient in all γδ T cells had nearly unchanged Ig levels and did not develop autoantibodies. Removing IL-4 abrogated the increases in IgE, antichromatin antibodies, and autoantibodies in the partially γδ-deficient mice. Our data suggest that γδ T cells, controlled by their own cross-talk, affect IL-4 production, B-cell activation, and B-cell tolerance

Electrophysiological Signatures of Spatial Boundaries in the Human Subiculum.

Environmental boundaries play a crucial role in spatial navigation and memory across a wide range of distantly related species. In rodents, boundary representations have been identified at the single-cell level in the subiculum and entorhinal cortex of the hippocampal formation. Although studies of hippocampal function and spatial behavior suggest that similar representations might exist in humans, boundary-related neural activity has not been identified electrophysiologically in humans until now. To address this gap in the literature, we analyzed intracranial recordings from the hippocampal formation of surgical epilepsy patients (of both sexes) while they performed a virtual spatial navigation task and compared the power in three frequency bands (1-4, 4-10, and 30-90 Hz) for target locations near and far from the environmental boundaries. Our results suggest that encoding locations near boundaries elicited stronger theta oscillations than for target locations near the center of the environment and that this difference cannot be explained by variables such as trial length, speed, movement, or performance. These findings provide direct evidence of boundary-dependent neural activity localized in humans to the subiculum, the homolog of the hippocampal subregion in which most boundary cells are found in rodents, and indicate that this system can represent attended locations that rather than the position of one\u27s own body

Discovery of hemocompatible bacterial biofilm-resistant copolymers

© 2020 The Authors Blood-contacting medical devices play an important role within healthcare and are required to be biocompatible, hemocompatible and resistant to microbial colonization. Here we describe a high throughput screen for copolymers with these specific properties. A series of weakly amphiphilic monomers are combinatorially polymerized with acrylate glycol monomers of varying chain lengths to create a library of 645 multi-functional candidate materials containing multiple chemical moieties that impart anti-biofilm, hemo- and immuno-compatible properties. These materials are screened in over 15,000 individual biological assays, targeting two bacterial species, one Gram negative (Pseudomonas aeruginosa) and one Gram positive (Staphylococcus aureus) commonly associated with central venous catheter infections, using 5 different measures of hemocompatibility and 6 measures of immunocompatibililty. Selected copolymers reduce platelet activation, platelet loss and leukocyte activation compared with the standard comparator PTFE as well as reducing bacterial biofilm formation in vitro by more than 82% compared with silicone. Poly(isobornyl acrylate-co-triethylene glycol methacrylate) (75:25) is identified as the optimal material across all these measures reducing P. aeruginosa biofilm formation by up to 86% in vivo in a murine foreign body infection model compared with uncoated silicone