bluuebunny/crossref_metadata_2025_split huggingface dataset:
The impact of aging on pulmonary microvascular endothelial cell barrier function
Authors: Manji Aminmohamed , Mehta Sanjay , Wang Lefeng , Pape Cynthia , Gill Sean 
Published: May 2023

Elderly individuals have substantially elevated morbidity and mortality during conditions of lung injury. However, the precise underlying mechanisms leading to this elevated mortality are ill-defined. Lung injury is associated with damage to pulmonary microvascular endothelial cells (PMVEC) leading to a compromised vascular barrier, fluid and protein leakage into the tissue, and subsequent respiratory dysfunction. Cell-cell junctions, including adherens junctions and tight junctions, are crucial for the maintenance of the endothelial barrier and have been shown to be dysregulated in various disease models. Pilot data from our lab demonstrated increased pulmonary vascular leak in aged mice during lung injury compared to young mice. We hypothesized that aging contributes to PMVEC barrier dysfunction due to impaired cell-cell junction integrity.To address our hypothesis, PMVEC isolated from young and aged mice were cultured in vitro until a confluent monolayer was formed. Endothelial barrier integrity was assessed by Evans blue-labelled albumin flux across the monolayers, as well as immunofluorescence staining of the adherens junction protein, vascular endothelial (VE)-cadherin, and tight junction protein, claudin-5. Localization of leak in relation to junctional proteins was performed using the fluorescently labelled macromolecule, NeutrAvidin. Proteomics analysis was conducted to identify differentially enriched pathways in young and aged PMVEC.Endothelial monolayers from aged mice exhibited a significant increase in albumin leak associated with augmented VE-cadherin and claudin-5 disruption vs. endothelial monolayers form young mice. Furthermore, NeutrAvidin staining localized to paracellular regions with VE-cadherin discontinuity was increased in PMVEC monolayers from aged mice vs. young mice, suggesting that the junctional disruption in aged PMVEC was directly associated with leak. Proteomics analysis revealed pathways known to be implicated in endothelial barrier dysfunction, including regulation of oxidoreduction and protein processing and trafficking, that were altered in PMVEC from aged mice.In summary, PMVEC from aged mice exhibit compromised barrier function, which is directly associated with impaired cell-cell junction integrity. We will next validate and target protein pathways identified in our proteomics analysis that were dysregulated in aged PMVEC to potentially rescue age-induced barrier dysfunction. These findings may highlight molecular pathways involved in predisposing aged individuals to worsened outcomes during lung injury, which can help in the development of therapeutics. Funded by Lawson Health Research Institute, CIHR, and Western University This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Chronic Pelvic Pain Develops in Sensory Neuron Conditional Asic3 Null Mice Subjected to Chemical Injury
Authors: Montalbetti Nicolas , Dalghi Marianela , Apodaca Gerard , Carattino Marcelo 
Published: May 2023

Sensitization of primary afferents is an important underlying mechanism for visceral hypersensitivity and pain. We investigated the contribution of acid-sensing ion channels (ASICs) in sensory neurons to the development of pain in a model of chemical-induced cystitis. ASICs are assembled as heterotrimers in bladder sensory neurons; however, the deletion of the ASIC3 subunit results in a loss-of-function phenotype with sensory neurons unable to discharge action potentials in response to acidification. In this study, conditional sensory neuron Asic3 knockout (KO) mice ( Asic3fl/fl;Avil-Cre+/- ) and control littermates ( Asic3fl/fl;Avil-Cre-/- ) received cyclophosphamide (CYP) (IP 80 mg/kg), or saline, every other day for five days. Experimental observations were made after one day (acute) or 14 days (chronic) after the last dose of CYP. In the acute setting, both control and conditional Asic3 KO mice treated with CYP exhibited an irritated bladder phenotype with a high number of voiding events of small volume. However, voiding activity normalized in both groups within two weeks of receiving CYP. In contrast, conditional Asic3 KO mice treated with CYP developed pelvic allodynia that persisted for at least two weeks, whereas control mice had no pain phenotype. In the chronic setting, no apparent edema or inflammatory cells were observed in bladders of control or conditional Asic3 KO mice, indicating that the pelvic allodynia seen in conditional Asic3 KO mice treated with CYP is likely driven by abnormal functioning of the nervous system and not by inflammation. To assess whether, in the chronic setting, the referred pelvic allodynia seen in conditional Asic3 KO mice treated with CYP is caused by sensitized primary afferents, we examined the firing evoked by sustained suprathreshold electrical stimulation of acutely isolated bladder sensory neurons. Sensory neurons were classified based of the sensitivity of the action potential to tetrodotoxin (TTX), as TTX-resistant (TTX-R) or TTX-sensitive (TTX-S). Strikingly, ~ 40% (11/17) of the bladder sensory neurons with TTX-R action potentials from conditional Asic3 KO mice treated with CYP exhibited aberrant firing (i.e., sensitization) in response to suprathreshold stimulation, compared to 3% (1/33) in control mice. These findings indicate that the pelvic allodynia seen in conditional Asic3 KO mice is driven in part by sensitized bladder afferents. Taken together, our studies support the notion that ASICs operate at the nerve terminals to modulate nociceptor excitability and sensitization. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Role of glycocalyx in breast cancer cell adhesion and transmigration across an in vitro blood-brain barrier (BBB)
Authors: Fu Bingmei , Li Yunfei 
Published: May 2023

On the surface of every mammalian cell, there is a matrix-like glycocalyx (GCX) consisting of proteoglycans and glycosaminoglycans (GAGs). Disruption of endothelial cell (EC) GCX by vascular endothelial growth factor (VEGF, VEGF-A165), a tumor secretion, was found to be an early event in tumor cell (TC) metastasis across vascular barriers. But how the TC secretion VEGF affects its own GCX to affect its adhesion and transmigration across EC barriers is unknown. Our recent study by employing Super-resolution Optical Microscopy (STORM) showed that while 1 nM VEGF greatly reduces the length and coverage of heparan sulfate (HS) of GCX at an in vitro BBB formed by human cerebral microvascular endothelial cells (hCMEC), it significantly enhances the coverage of HS on a malignant breast cancer cell, MDA-MB-231 (MB231). In the current study, we want to test the hypothesis that the differential effects of VEGF on the GCX of MB231 and that of the BBB favor MB231 adhesion and transmigration across the BBB for the metastasis. To test this hypothesis, we first generated an in vitro BBB by culturing hCMECs on a Transwell filter with 8 um pores. For adhesion, we added MB231 cells to the BBB under 1) no treatment; 2) after VEGF treatment for MB231 for 2h; 2) after VEGF treatment for the BBB for 2h; and 4) after VEGF treatment for both for 2h. After 1h adhesion, the number of adherent MB231 cells increased by 1.7-fold,1.5-fold and 2.4-fold, respectively for 2), 3) and 4) VEGF treatments, compared to no treatment. For transmigration, we add MB231 cells to the BBB under the same conditions as for adhesion. After 6 h, the number of transmigrated MB231 cells increased by 1.3-fold, 1.4-fold, and 1.6-fold, respectively, for 2), 3) and 4) VEGF treatments, compared to no treatment. Our results conform to our hypothesis that the reduced BBB GCX and enhanced MB231 GCX by VEGF favor MB231 adhesion to and transmigration across the BBB. Our findings also suggest a therapeutic intervention by targeting the glycocalyx-mediated breast cancer brain metastasis. Partially supported by NIH RO1NS101362 and 1UG3UH3TR002151. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Effects of CD8 T-cell transfer on post-myocardial infarction scar formation
Authors: Learmonth Maya , Corker Alexa , Troncoso Miguel , Broughton Philip , Baicu Catalin , Bradshaw Amy , Zile Michael , DeLeon-Pennell Kristine 
Published: May 2023

Post-myocardial infarction (MI) left ventricular scar formation and composition is one critical determinant of myocardial remodeling. CD8+ T-cells are adverse regulators of the post-MI remodeling process, leading to decreased cardiac function and survival. Based on our previous studies, we hypothesize that CD8+ T-cells impair cardiac function by altering scar composition, leading to poor tissue biomechanical properties.MI was induced by permanently ligating the left anterior descending coronary artery on C57BL6/J wildtype (WT; 3-7 months of age, n≥4/sex/Day post-MI) and CD8atm1mak (CD8-/-; 3-7 months of age, n≥4/sex/Day post-MI) mice. To test potential effects on the scar, CD8-/- mice were injected with either vehicle or naïve splenic CD8+ T-cells via tail vein, 4 hours post-coronary artery ligation. At day 7 post-MI, infarct tissue was collected and underwent passive stretch biomechanical analysis using an Aurora Scientific tension-length dual mode lever servosystem. To examine a possible mechanism of scar alteration, we tested the effects of recombinant granzymes (Gzm) B and K, which are highly expressed in CD8+ T-cells, on collagen cleavage using a fluorogenic collagen cleavage assay.Scar biomechanics of CD8-/- mice demonstrated increased regional stiffness compared to WT mice. Re-supplementation with splenic CD8+ T-cells decreased scar tissue stiffness by more than 2-fold compared to vehicle treated CD8-/- mice, mimicking the biomechanics of WT mice. Ex-vivo GzmK demonstrated the ability to cleave collagen in a concentration and temporal-dependent manner. Cleavage of the collagen substrate was detected within a 6-hour period at GzmK concentrations as low as 50 nanomolar (nM), and as early as 2-hours at 100 nM. GzmK at a concentration of 100 nM demonstrated a 10-fold greater collagen cleavage capacity compared to GzmB at the same concentration suggesting that GzmK actions may be distinctly separate from that of GzmB in the post-MI setting.In conclusion, our data demonstrates that CD8+ T-cells regulate cardiac fibrosis likely through release of granzymes, leading to alterations in the biomechanical capability of the left ventricle. This project was funded by the National Institutes of Health T32GM123055, GM113278; the American Heart Association Innovator Project IPA35260039; the Biomedical Laboratory Research and Development Service of the Veterans Affairs Office of Research and Development Award IK2BX003922; and South Carolina Translational Research Center UL1TR001450. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Impact of increasing insulin resistance on cerebral perfusion in adolescents
Authors: Wannebo Brett , Ward Aaron , Bolin Shawn , Eldridge Marlowe , Wieben Oliver , Carrel Aaron , Hermann Bruce , Jones Jana , Schrage William 
Published: May 2023

Background: Adolescence is a key growth period that heavily influences future brain health. Approximately 1 in 5 adolescents are obese in the US, and up to half of them exhibit some form of insulin resistance (IR). Notably, insulin acts as a metabolic hormone, a neurotrophic growth factor, and a vasodilator. Reduced vasodilation may lead to reduced cerebral perfusion, and lower perfusion in older adults is associated with reduced cognition and increased risk of stroke and neurologic disease. Given this background, IR may negatively impact adolescent brain health in part due to lower brain perfusion. Therefore, we hypothesized cerebral perfusion would decrease as the level of insulin resistance increased. Method s: Adolescents (n=15, 4 females, age 15±2 yr) were studied. IR was estimated by calculating HOMA-IR (using fasting glucose and insulin), which spanned a spectrum of IR up to but excluding diabetes. Subjects underwent a magnetic resonance imaging (MRI) study visit to assess cerebral perfusion using arterial spin labeling (ASL). The CAT12 toolbox extension for SPM12 was used to process MRI data. Heart rate (HR), mean arterial pressure (MAP), and end tidal CO2 (ETCO2) were assessed. Significance was determined using linear regression and set at p≤0.05. Results: Results are mean±SD. HR (72±10 bpm, p=0.98), MAP (73±6 mmHg, p=0.67), and ETCO2 (37±2 mmHg, p=0.91) were similar across HOMA-IR (0.5 to 3.8). Perfusion (ml/100g/min) at the amygdala (r2=0.33, p=0.02) and parahippocampal gyrus (r2=0.28, p=0.04) decreased as HOMA-IR increased. Borderline significant decreases were found for total gray matter (r2=0.26, p=0.051), anterior cingulate cortex (r2=0.26, p=0.052), and hippocampus (r2=0.23, p=0.07) perfusion as HOMA-IR increased. No associations were found between HOMA-IR and the following: total white matter (r2=0.18, p=0.11), precuneus (r2=0.20, p=0.10), thalamus proper (r2=0.14, p=0.17), and entorhinal cortex (r2=0.16, p=0.14) perfusion. Total gray matter (p=0.49) and white matter (p=0.73) volume had no significant relationship with HOMA-IR. HOMA-IR was not associated with any differences in regional volumes. Conclusions: Our results suggest with increasing HOMA-IR there is a significant reduction in gray matter perfusion in key brain regions associated with memory in adolescents. In contrast, structural changes were not detected, indicating functional decrements occur prior to structural deficits. These findings support our hypothesis that cerebral perfusion is associated with insulin resistance in adolescents, which may negatively impact long-term brain health. NIH R21 HD097510 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Inflammation modulates the activation of autophagy in C2C12 myotubes
Authors: Rogers Robert , Howe Parker , Hayes Annemarie , Yeung Justin , Staudinger Jeffrey 
Published: May 2023

Autophagy is a cellular housekeeping process by which proteins and damaged organelles are targeted for engulfment by autophagosomes ultimately culminating in degradation within the lysosomes. Chronic inflammation has been shown to disrupt normal physiological homeostasis leading to increased risk of cardiovascular disease, type 2 diabetes mellitus and muscle atrophy. The purpose of this study was to investigate whether inflammation disrupts the activation of autophagy in C2C12 myotubes. Myoblasts were grown in 10% fetal bovine serum supplemented DMEM until confluent and then differentiated for 5 d in 2% FBS-DMEM. Autophagy was monitored by Western blotting for changes in p62/sequestosome 1 (p62/sqstm1) and in the lipidation status of microtubule-associated protein light chain 3 (LC3) where the protein separates into LC3-II and LC3-I by electrophoresis. Changes in the ratio of LC3-II to LC3-I represent a method to monitor initiation of autophagy. Rapamycin (25-50 nM) for 48 hr successfully initiated autophagy as observed by a decrease in p62/sqstm1 and increase in LC3-II/LC3-I. Incubation of cells with lipopolysaccharide (LPS) to activate the inflammatory process for 48 hr reduced cell diameter and this decrease was partially attenuated by rapamycin (50 nM). LPS disrupted the activation of autophagy by rapamycin. Exposure to LPS for 48 hr increased p62/sqstm1 levels, but this was abolished with co-incubation of LPS and rapamycin; however, LC3-II/I was enhanced by co-incubation with LPS and rapamycin. To further investigate the components of the inflammatory process, cells were exposed to interleukin-6 (IL-6). Acute IL-6 exposure for 3 hr at 10 ng/mL or 50 ng/mL modulated basal autophagy as observed by an increase in the ratio LC3-II/LC3-I. In addition, chronic IL-6 exposure disrupted the initiation of autophagy by rapamycin. B-cell lymphoma 2 (Bcl-2) associated athanogene 3 (Bag3) is a molecular chaperone that plays a role in shuttling proteins to the proteasome but also in targeting proteins for degradation through autophagy. We observed that in our experiments Bag3 levels decreased concurrently with rapamycin treatment, but frequently decreased as p62 increased when exposed to LPS, and vice versa. Furthermore, Bag3 co-localizes with LC3 in primary hepatocytes further indicating a role for Bag3 in the targeted autophagy process. In conclusion, autophagy is disrupted by components of the inflammatory process in C2C12 myotubes. Future investigation may include the protective influence of autophagy in the process of atrophy. Intramural grant award from Kansas City University. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Dietary intake of macro and micronutrients correspond with sleep behaviors in collegiate female soccer players
Authors: Rentz Lauren , Leary Miriam , Bryner Randy 
Published: May 2023

Both macro and micronutrient intakes have an impact on sleep behaviors in athletes, notably sleep onset latency and sleep efficiency. Proper nutrient intake supports daily muscle repair and synthesis of sleep regulating compounds (e.g., serotonin and melatonin). The objective of this study was to evaluate the relationship between sleep behaviors and dietary intake in elite college female athletes. It was hypothesized that dietary carbohydrates and vitamin intake would be associated with both sleep timing and consistency. Twenty-three female Division I collegiate soccer players were evaluated for their sleep and nutritional patterns. Athletes wore an OURA ring (OURA Health, Oulu, Finland) each night for 31 days during the competitive season. During the final three days, athletes recorded their dietary intake using the Automated Self-Administered 24-hour Dietary Assessment Tool (ASA24). All athletes were exposed to the same travel schedule throughout the evaluation period, which did not differ by more than one time zone. Pearson’s R with Bonferonni Correction was used to assess the relationship between the average daily intake of various nutrients with average nightly sleep behaviors. Total Vitamin B12 ( r=-0.63), added Vitamin B12 ( r=-0.62), and Vitamin C ( r=-0.53) were negatively correlated with average bedtimes (P<0.01) while added Vitamin B12 ( r=-0.61) and Vitamin C ( r=-0.50) were also negatively associated with wake times (P<0.01). Greater dietary intake of kcals from carbohydrates, with respect to recommended consumption, was associated with earlier bedtimes ( r=0.41, P<0.05). In conclusion, greater intake of carbohydrates and vitamins B12 and C are associated with ideal sleep behaviors. A potential mechanism accounting for this relationship could be the enhanced contribution of antioxidants and glycemic load on the synthesis of vital hormones for sleep regulation, including serotonin and melatonin. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Acute fatigue induces paradoxical increases in velocity and power in a sex and myosin isoform dependent manner
Authors: Ricci Austin , Privett Grace , Needham Karen , Callahan Damien 
Published: May 2023

OBJECTIVE or our study was to identify effects of acute fatigue on myofibrillar components and their function that persist beyond modifications to intracellular metabolic perturbations. Our HYPOTHESIS was that acute fatigue would induce differential phosphorylation in regulatory proteins in the sarcomere that would reduce tension and increase velocity and power. We used the following METHODS to test that hypothesis. Seven healthy, competitive athletes were recruited to participate (3 male, 4 female), entailing one session of unilateral fatiguing knee extension exercise to the point of task failure. Immediately after, bilateral percutaneous needle muscle biopsy was performed on the vastus lateralis muscle, providing a “fatigued” and “not fatigued” sample. Tissue was separated for phosphoproteomic analysis (western blot and isoelectric separation) and single fiber contractile mechanics (isotonic load clamps; isometric tension, velocity and power). Following mechanical assessment, myosin heavy chain (MHC) isoform was determined for each fiber via SDS-PAGE. Our RESULTS found no effect of fatigue on isometric tension across all fiber types. However, maximum shortening velocity was increased along with contractile power, consistent with our hypotheses. Surprisingly, our results varied by sex and fiber type, such that velocity was increased primarily in MHC IIA/X fibers in males, whereas females demonstrated a blunted response to fatigue. While baseline variation in regulatory protein phosphorylation (Myosin Binding Protein C; MyBP-C) were significantly correlated with power output in contractile power in fast isoforms (MHC IIA, MHC IIA/X) we did not detect significant alterations in phosphorylation of this protein with fatigue. We CONCLUDE that fatigue causes paradoxical increased in velocity and power that are particularly evident in males. While our measurement of MyBP-C phosphorylation did not detect effects of fatigue, other potential sarcomeric proteins may explain this paradoxical response to acute fatigue. Wu Tsai Human Performance Alliance This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.