bluuebunny/crossref_metadata_2025_split huggingface dataset:
A versatile chaperone network promoting the aggregation and disaggregation of misfolded proteins
Authors: Bukau Bernd , Nillegoda Nadinath , Wentink Anne , Ungelenk Sophia , Ho Chi‐ting , Mogk Axel 
Published: November 2023

Misfolded proteins are sticky and tend to form intracellular aggregates underpinning age‐related deterioration and disease. Normally, multi‐tiered cellular quality control systems monitor and repair protein damage, limiting aggregation. Severe stress however overloads these systems allowing aggregates to accumulate. This activates a cellular machinery which mediates the organized aggregation of misfolded proteins as well as the subsequent solubilisation and refolding and of aggregated proteins. This machinery plays a pivotal role in cell survival under protein folding stress and in counteracting disease and age‐associated cell toxicities.Small heat shock proteins (sHsp) constitute an evolutionary conserved yet diverse family of chaperones acting as first line of defense against proteotoxic stress. The yeast sHsps Hsp42 and Hsp26 promote the storage of misfolded proteins in native‐like conformation which facilitates disaggregation by ATP dependent chaperone systems. In plants, fungi and bacteria the central disaggregation machinery is a powerful bi‐chaperone system comprised by the AAA+ disaggregase Hsp100 (Hsp104, ClpB) and the cooperating Hsp70 chaperone with its co‐chaperones, J‐domain proteins (JDPs) and nucleotide exchange factors (NEFs). Metazoan cells lack Hsp100 disaggregases, but have evolved a potent Hsp70‐based disaggregation machinery which relies on synergistic action of Hsp70 and its co‐chaperones. This activity has broad specificity and can even disassemble amyloid fibrils of α‐synuclein. A different disaggregation strategy has therefore evolved in evolution of metazoa.Support or Funding InformationGerman Research Foundation (DFG)
Modeling cellular network dynamics of liver homeostatic renewal
Authors: Vadigepalli Rajanikanth , Cook Daniel , Ogunnaike Babatunde 
Published: November 2023

Recent experimental studies identified specific subpopulations of self‐renewing hepatocytes with ability to populate the liver during homeostatic maintenance of the tissue. It remains an open question as to how this process of precursor transformation into mature hepatocytes is regulated by molecular pathways and tissue microenviroment to yield robust homeostatic renewal. We explored the contribution of putative control mechanisms that yield robustness to the renewal process by developing and analyzing a computational model of liver homeostatic renewal that considers a cellular network of precursor cells and mature hepatocytes. We demonstrate that the renewal network without feedback and nonlinear dynamics cannot maintain liver tissue in response to repeated injury. We modified the model to consider multiple alternatives including capacity constraints on proliferation, inhibition of precursor proliferation and transformation by mature hepatocytes, and putative precursor replenishment from non‐hepatocyte sources. We followed a Design of Experiments approach to investigate the system dynamics under all possible combinations of feedback configurations, specifically characterizing recovery of precursor and mature hepatocyte populations in response to a wide variety of disturbances. This unbiased exploration led us to identify a model configuration that is most robust in maintaining liver homeostasis. We compared the dynamics of the most robust model configuration with the available experimental data on the effects of hepatocyte senescence and stem cell transplantation on liver tissue renewal. We investigated the dynamics of the homeostatic renewal network in response to chronic repeated injury. Our results suggest that increasing frequency and magnitude of chronic repeated injury destabilizes the liver homeostasis within several months, which is inconsistent with epidemiological observations of a much slower decay of liver function over several years. We interpret these findings as suggestive of the presence of additional stabilizing controls potentially by the non‐parenchymal cells. We modified the model to include manipulation of the liver microenvironment signals by the liver non‐parenchymal cells as an additional layer of feedback control over hepatocyte levels. Our simulations and model analyses lead us to predict that robust homeostatic balance of hepatocytes is achieved by a combination of intrinsic system stability and control by non‐parenchymal cells. Taken together, our computational modeling study suggests that homeostatic renewal and maintenance of liver tissue is achieved through a coordinated regulation of the process by a combination of cell‐intrinsic and intercellular feedback control mechanisms.Support or Funding InformationResearch Support: R01 AA018873, T32 AA007463, F31 AA023445
Role of Hepatic O‐GlcNAcylation on Acetaminophen‐Induced Liver Injury
Authors: McGreal Steven , Bhushan Bharat , Walesky Chad , McGill Mitchell R , Weemhoff James L , Jaeschke Hartmut Jaeschke , Zhang Zhen , Tan Ee , Slawson Chad , Zachara Natasha E 
Published: November 2023

Overdose of acetaminophen (APAP), the most widely used analgesic, results in acute liver failure. We have investigated the role of a post‐translational modification of proteins called O‐GlcNAcylation in pathogenesis of APAP‐induced liver injury, where a single β‐D‐N‐acetylglucosamine (O‐GlcNAc) moiety is added to proteins by an enzyme called O‐GlcNAc transferase (OGT) and removed by an enzyme called O‐GlcNAcase (OGA). Male C57BL/6J mice were treated with 300 mg/kg APAP followed by Thiamet‐G (TMG, 400 mg/kg) a specific inhibitor of OGA that induces O‐GlcNAcylation, 1.5 hr after APAP administration. Progression of liver injury was studied over a time course of 0 to 24 hr. TMG treatment resulted in significant increase in hepatic O‐GlcNAc. The mice treated with 400 mg/kg TMG exhibited significantly higher APAP‐induced liver injury as indicated by increase in serum transaminase levels and histopathological analysis, as well as a prolonged JNK activation. Treatment with TMG did not affect hepatic CYP2E1 levels, APAP protein adduct formation, APAP induced mitochondrial damage, hepatic glutathione (GSH), or depletion of GSH after APAP treatment. C57BL/6J mice were also treated with 50 mg/kg TMG every other day for 15 days followed by 300 mg/kg APAP and sacrificed at 24 hr. Mice treated with 50 mg/kg TMG showed a similar increase in APAP‐induced liver injury. Next we used hepatocyte specific OGT knockout mice (OGT KO), which have decreased O‐GlcNAcylation to study APAP toxicity. OGT KO and WT control mice were treated with 300 mg/kg and sacrificed on a timecourse from 0–24 hr. OGT KO mice showed dramatic decrease in liver injury as compared to WT mice. APAP protein adducts was significantly decreased in OGT KO mice when compared to WT control mice. There was no difference CYP2E1 activity showing that OGT KO did not alter cytochrome P450 levels and alter APAP metabolism. Hepatic GSH depletion was equal in OGT KO and WT mice but GSH was rapidly replenished by 6hr after APAP treatment in OGT KO mice, while WT mice did not fully replenish until 24hr post APAP. Taken together, these data indicate that induction in cellular O‐GlcNAcylation exacerbates and decrease in O‐GlcNAcylation protects from APAP induced liver injury. These studies have identified a novel mechanism of pathogenesis of acute liver injury induced by APAP and highlighted a novel therapeutic target for acute liver failure.Support or Funding InformationR01DK098414
The Regulatory Role of CD99L2 in Inflammation
Authors: Rutledge Nakisha S , Watson Richard L , Sullivan David P , Muller William A 
Published: November 2023

The inflammatory response involves a series of steps in which inflammatory stimuli activate endothelium of local blood vessels to express adhesion molecules that recruit circulating leukocytes from the blood. Transendothelial Migration (TEM) is a crucial step in the inflammatory response as it is the process in which leukocytes leave the bloodstream to enter the inflamed tissues. PECAM and CD99 are two molecules important for the initiation and completion of TEM, respectively.CD99‐like 2 (L2) is a highly glycosylated 52 kD type‐1 membrane protein that is the only molecule in the genome related to CD99. Similar to CD99, L2 is expressed at the borders of endothelial cells and on the surface of leukocytes. Blocking L2 using antibodies significantly reduces the recruitment of neutrophils and monocytes to sites of inflammation in mice. Similarly, L2 knockout mice have an inherent defect in transmigration into inflammatory sites. Thus, L2 has been shown to be another important protein for TEM; however, how it regulates this process is not known. L2 is different enough from CD99 (60% larger and with only 38% sequence identity) that it is not clear whether it regulates TEM by the same mechanism as CD99. Furthermore, all of the published studies on L2 have been performed in mice. The role of L2 in TEM of human cells has yet to be shown. In order to study the mechanism used by L2 and the relevance to human inflammation, we studied the role of L2 on human cells in vitro. Using an endpoint TEM assay, we show that inhibiting L2 function using either a blocking antibody or shRNA reduces TEM of human monocytes to 30% of control levels. Like PECAM and CD99, homophilic interactions between L2 on leukocytes and L2 on the endothelium are required for this process.Previous studies have shown that PECAM regulates a step in TEM that is “upstream” of the one regulated by CD99. In order to determine where L2 functions in relation to PECAM and CD99, we used an extended version of our TEM assay, the sequential block assay. Our data show that L2 functions downstream of PECAM and upstream of CD99. Preliminary data suggest that L2 can promote TEM by engaging either the signaling pathway used by PECAM or the one used by CD99. These data are consistent with L2 functioning between the PECAM and CD99. The data we have obtained in both humans and mice identify L2 as a potential target for anti‐inflammatory therapy.Support or Funding InformationT32‐5T32AI007476‐19R37‐HL064774F31‐HL131355‐01
Entamoeba histolytica Stimulates the Release of the Alarmin Molecule HMGB1 by a PI3 Kinase Dependent Mechanism
Authors: Begum Sharmin , Moreau France , St‐Pierre Joëlle , Chadee Kris 
Published: November 2023

The enteric protozoan parasite Entamoeba histolytica (Eh) is responsible for the development of amebiasis in humans. In ~90% of cases, Eh resides in the intestinal lumen asymptomatically and for unknown reasons this asymptomatic relationship breaks down and parasites invade the underlying colonic mucosa. Host pro‐inflammatory responses induced by the Eh are critical in disease pathogenesis but the exact underlying mechanisms of this response is poorly understood. Contact between Eh and macrophage triggers a raging pro‐inflammatory response by activating NLRP3 inflammasome (IL‐1β) and other uncharacterized pathways (TNF‐α) but it is not clear how non‐contacted bystander immune cells sense invasive Eh. High Mobility Group Box 1 protein (HMGB1) is a critical mediator of inflammation during infection and to shape the magnitude and degree of the inflammatory response. HMGB1 is a non‐histone nuclear protein, which have overlapping binding side with histone H1 in the chromatin. It is released in the extracellular space during infection by activated or damaged immune cells and act as an alarmin molecule. In this study, we identified HMGB1 as the earliest alarmin signals released by Eh‐contacted macrophages that can cross talk with bystander immune cells. Human monocytic cell line (THP‐1) and mouse bone marrow derived macrophages (BMDMs) were treated with live Eh and Eh components and western blotting was used to detect HMGB1 secretion. Stimulation with live Eh but not Eh components triggered robust time‐dependent (as early as 5 minutes) secretion of HMGB1. Early release of HMGB1 by macrophages was actively secreted and independent of cell death as quantified by the detection of acetylated HMGB1 by immunoprecipitation studies and translocation of HMGB1 from the nucleus to the cytoplasm by confocal microscopy. Two major virulent factors of Eh were critical for HMGB1 protein secretion, the Gal‐lectin surface adhesin and cysteine protease 5 (EhCP5). Eh coupling to macrophages via the Gal lectin and EhCP5 induced the release of HMGB1 by a PI3 kinase dependent mechanism. NLRP3 inflammasome activation was not a prerequisite for HMGB1 secretion as similar results were obtained using BMDMs from caspase‐1−/− mice. Our results have identified that HMGB1 release is the earliest innate response upon Eh contact with macrophages that serve as a danger signal to sense parasite invasion and to signal bystander cells to enhance inflammation in innate host defense against amebiasis.Support or Funding InformationGrant Support: NSERC
Team‐based Learning in the Neuroanatomy Lab of an Undergraduate Human Anatomy and Physiology Course – a Lesson Study
Authors: Schanandore James , Liu Sumei , Schwartz Christine , Stapley Ryan 
Published: November 2023

Students in the Human Anatomy and Physiology Laboratory at the University of Wisconsin‐La Crosse are responsible for learning a large amount of material. In particular, the neuroanatomy lab is challenging for students due to the complex spatial relationships among structures in the nervous system. Team‐based learning (TBL) is an active learning approach that has potential to engage students, allow instructors to provide immediate feedbacks, and help students to learn anatomy effectively. We conducted a lesson study on using TBL in the neuroanatomy lab. Eleven lab sections with a total of 179 undergraduate students participated in this lesson study. The TBL module included a pre‐lab reading assignment, a recorded video demonstrating sheep brain dissection, an individual readiness assurance test (pre‐test), an instruction for team activities, a team readiness assurance test, and a team application problem. During the lab, student learning, engagement, and group dynamics were observed by at least two observers. Two weeks later, a post‐test was given to assess the impact of TBL on student learning retention. To assess student perceptions of TBL, a survey was administered after the laboratory unit exam. The results suggested that students achieved higher mean posttest scores (70.17±1.40%, n =177) two weeks after the TBL module comparing to the pretest scores (43.08±1.40%, n=177; p < 0.001). Comments from the observers indicated that TBL promoted student participation, team work, and peer teaching. The results of the student survey showed that most students believed that TBL helped them understand laboratory content (82.12%), correct misconceptions (78.78%), develop information synthesizing skills (67.60%), and prepare them for the laboratory examination (74.86%). The survey also indicated that over 80% of the students have a positive attitude toward team working and collaboration. We concluded that TBL was an effective exercise for the neuroanatomy lab and that this learning approach was viewed positively by students, instructors, and outside observers. Based on this, we will explore other topics where TBL could be an effective learning tool in the Human Anatomy and Physiology Laboratories.Support or Funding InformationThis project was supported by a grant from the Center of Advanced Teaching and Learning at the University of Wisconsin‐La Crosse. We greatly appreciate Marjorie Bazluki, Lukas Buttke, Bill Cerbin, Faye Ellis, Khendum Gyabak, Deb Hoskins, Lisa Kobs, Bryan Kopp, Emily Murphy, and Renee Redman for their time spent observing the lesson. All authors contributed equally to this work.
Utilizing Pre‐ and Post‐Exercise Changes in Heart Rate as a Method of Teaching the Scientific Method to Second Grade Students
Authors: Taylor Jessica C , Mercier Betsy 
Published: November 2023

Background/PurposeSchool children of all ages can learn and utilize the scientific method to hone problem‐solving skills. Heart rate measurements taken before and after various playground‐style exercises (PSE) are an easy and effective modality for teaching the scientific method. Therefore, the purpose of this experiment was to hypothesize and subsequently test 4 PSE and determine which caused the greatest increase in heart rate.MethodsSecond‐grade students (n=20) were introduced to the steps of the scientific method and the research question concerning heart rate (HR) increases. The students were then asked to hypothesize which of the four PSE would increase HR the most. Next, the students were taught to palpate and count a resting (control) radial pulse (3 practice measurements) and then the control HR was obtained and recorded. Students were then randomly divided into four groups of five students and taken to the playground to perform the PSE. Following completion of the PSE, exercise HR were obtained and recorded. Data from averaged PSE HR was compared with control HR.ResultsRunning was hypothesized as the PSE which would increase HR the most. However, jumping jacks increased HR more than any other exercise, refuting the classes' hypothesis.DiscussionThe students were able to demonstrate the ability to work through the steps of the scientific method and form a question, hypothesize, collect data and analyze the results. They were surprised by the data, but learned that refuting your hypothesis does not make you wrong, but instead leads to another question.
“The Locomotion”: Not the Pop Song but an Activity Designed to Integrate Energetics and Mechanics to Understand Human Movement
Authors: Elmer Steven 
Published: November 2023

Understanding healthy and pathological movement requires integration of both energetics and mechanics. These concepts are often taught in isolation in exercise physiology and biomechanics courses, respectively. In the Department of Kinesiology and Integrative Physiology at Michigan Technological University I designed and implemented “The Locomotion” unit for undergraduate exercise science students (n = 16) to emphasize the links between the energetics and mechanics of human locomotion. Background content on 1) muscle mechanics, 2) work, power, and energy, and 3) metabolic cost of transport was off‐loaded to self‐paced video lectures to allow more class time for the following active learning activities. Day 1‐Journal Club: students read Bramble and Lieberman's historic cover‐of‐Nature publication (“Endurance Running and the Evolution of Homo”, >1,000 citations) and worked in small groups to compare and contrast the mechanics and energetics of human walking and running as well as bipedal and quadrupedal locomotion. Day 2‐Data Collection: students explored the basis for Bramble and Lieberman's endurance running hypothesis by collecting oxygen consumption during walking and running across a broad range of speeds (e.g., 4–5 min trials, walking at ~0.5–2.5 m/s, running at ~2.5–5.0 m/s) and calculating the metabolic cost of transport (ml O2/kg/km and J/kg/m) for each movement. Day 3‐Intepretation and Applications: students graphed their metabolic cost of transport data and compared to those curves reported in Figure 2 of the Nature publication. Subsequently, metabolic cost of transport findings were connected to peer‐reviewed publications highlighting applications in sports, rehabilitation, military, and space exploration. Following this series of in class activities, students' perceived knowledge of human movement increased (2.6 ± 0.8 vs. 4.2 ± 0.8 Likert scale units, P < 0.01). Majority of students (>85%) agreed or strongly agreed that they stayed engaged, enjoyed the activities, and recommended that the activities be performed again. This locomotion unit provided a novel approach for integrating the energetics and mechanics of human movement and was favorably perceived by students. Finally, if “The Locomotion” unit can only have similar success to the pop song (American Top 5 list ‐ 3 times over 3 different decades) it will be a smashing hit!Support or Funding InformationMichigan Technological University Center for Teaching and Learning
The use of Livescribe&[trade] Echo® pen recordings to make videos of Jeopardy‐like questions to encourage spaced out, interleaved study by students
Authors: Chapman Jane S , Denofrio‐Corrales Lauren 
Published: November 2023

Oftentimes in the first semester of A&P, the structure and function of muscle fibers and neurons provides students with their first exposure to how things function at a molecular and mechanistic level which can be quite daunting and overwhelming. Exams assessing student understanding of those topics usually have the lowest average of all the unit exams. Trying to find ways to help students be successful in learning these foundational topics is of continual interest to the authors.Feedback from reflective questions on exams indicated that many students were making and using flashcards to study for the exams, in a one and done fashion, using them only for that exam despite the accumulative nature of exams over the course of the semester.In an effort to reduce the time students spend on making flashcards, a method that doesn't easily or always translate into durable learning and application of concepts, the Livescribe™ Echo® pen was used to make “Jeopardy‐like Flashcard” videos which were posted on a classroom management system and assigned in an interleaved, spaced out manner by the instructor. Enabled tracking statistics were used to ascertain student use of the Jeopardy‐like flashcard videos to see if viewing the videos could be linked to improved performance on content‐related test questions.Topics for the Jeopardy‐like flashcards, included in this preliminary study, were muscle anatomy, muscle physiology and neuron physiology which were all topics covered the on the subsequent unit exam. Preliminary results suggest that students who viewed the Jeopardy‐like flashcard videos tended to do better on the knowledge and comprehension part of the exam as well as the application part of the exam.