bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating the Effect of Rapamycin on Impaired Proteostasis in Aged Skeletal Muscle After Disuse Atrophy
Authors: Fuqua Jordan , Brecheen Parker , Miller Benjamin 
Published: May 2024

Older individuals undergo loss of muscle mass and strength, which can be compounded during bed rest and extended hospital stays. Adult and aged individuals lose muscle mass at similar rates during periods of disuse; however, only aged skeletal muscle fails to fully recover once activity resumes. Current efforts to facilitate skeletal muscle recovery are aimed at increasing myofibrillar protein synthesis by stimulating mTORC1(mammalian target of rapamycin complex 1), a major regulator of protein synthesis. However, we showed that skeletal muscle in aged rats already has higher rates of myofibrillar protein synthesis and mTORC1 activity than adult rats. We also showed that aged skeletal muscle has an accumulation of insoluble ubiquitinated proteins compared to adult muscle, indicating impaired proteostasis and possibly impaired autophagy degradation. We hypothesized that mTORC1 inhibition via rapamycin administration would reduce protein synthesis and the accumulation of p62 aggregates, facilitating recovery in aged skeletal muscle after disuse. Methods: Adult (10 months) and old (26 months) OKC HET rats were hindlimb unloaded (HU) for 14-days to induce atrophy, followed by subsequent 14 days of reloading (RE) through normal ambulation. Animals were fed either a control or rapamycin-supplemented (42 ppm) diet. To determine bulk protein synthesis, rats were labeled with deuterium oxide (D2O) during weight bearing (WB), HU, and RE, (n=4-6 per time point per group). Finally, to assess the presence of autophagy related protein aggregates we immuno stained for Sequestosome 1/p62, an autophagy cargo receptor protein. Results: Our data showed that myofibrillar protein synthesis rates were elevated in the old muscle compared to the adult ( k = 0.029 1/day ±0.002 vs. 0.039 1/day ±0.002, p<0.0001), and that protein synthesis rates were lower in the old rapamycin cohort (k = 1/day ±0.002 vs. 1/day ±0.003, p<0.0001). Furthermore, p62 puncta was three-fold more abundant (p<0.01) in aged skeletal muscle, compared to the adult muscle. Although the sample size is small, when comparing p62 puncta in the old rapamycin group to the old controls, there was no difference between the cohorts. Conclusion: We show that mTORC1 inhibition reduces protein synthesis in aged skeletal muscle. We also show that aged muscle has more p62 aggregates compared to adult skeletal muscle, indicating that autophagy related targets are not being degraded effciently with age. Further analyses will assess the effects of mTORC1 inhibition on other proteostatic mechanisms in atrophied skeletal muscle of aged rats. NIA Training Grant: 5T32AG052363-04VA I01 BX005592 APS SURF. This is the full abstract presented at the American Physiology Summit 2024 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.
Characterization of Sex-Dependent Differences in Brain Microvascular Bioenergetics
Authors: Sure Venkata , sakamuri Siva , Oruganti Lokanatha , Chandra Partha , merdzo Ivan , Lindsey Sarah , Mostany Ricardo 
Published: May 2024

Background: Women experience increased incidence of stroke-related deaths and lifetime risk of Alzheimer's disease (AD). Microvascular dysfunction has been implicated in the pathogenesis of ischemic stroke and AD. Our objective is to investigate the sex-dependent differences in bioenergetics of young mouse brain microvessels (BMVs). Methods: BMVs were isolated from young male and female mice (3-4 months), using a combination of gradient centrifugation and filtration (300μm and 40μm filters) methods. Extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) of BMVs were measured utilizing the Agilent Seahorse XFe 24 analyzer. The levels of proteins and mRNAs of mitochondrial respiratory complexes were measured by western blot and RT-PCR, respectively. Citrate synthase (CS) enzyme activity and ATP levels were determined in lysates of BMVs. Results: Real-Time ATP Rate assay demonstrated a decreased total ATP production rate and ATP contribution from both glycolysis and oxidative phosphorylation (OxPhos) in BMVs from females compared to males. Mitochondrial stress test assay revealed significantly lower values of several mitochondrial respiratory parameters, including basal respiration, ATP production, maximal respiration, spare respiratory capacity, and proton leak in BMVs from females compared to males. Glycolytic Rate assay uncovered reduced basal glycolysis, proton efflux rate (PER) originating from basal glycolysis, and the mitoOCR/glycoPER ratio in BMVs from females compared to males. Interestingly, no sex-dependent differences were observed in basal PER and post-2-DG acidification rates in BMVs. Mito Fuel Flex Test assay showed no sex-dependent difference in the utilization of glucose, glutamine, and long-chain fatty acids as fuel substrates in BMVs. ATP measurements confirmed the reduced ATP levels in BMVs from females compared to males. Measurements of CS activity revealed no sex-dependent difference in the BMVs. Lastly, Western blot and RT-PCR experiments indicated no differences in either protein or mRNA levels of various mitochondrial complex protein levels.Conclusions: Female BMVs showed reduced mitochondrial respiratory and glycolytic parameters compared to male BMVs although relative contribution of various substrates for energy production were not different. These sex-dependent differences involving glycolysis and OxPhos make the microvasculature vulnerable to injury in females. Funding sources: NIH grants AG074489 and NS114286 (PVGK and RM). This is the full abstract presented at the American Physiology Summit 2024 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.
Functional profiling of resident cells during vascular aging
Authors: Brady Travis , Gerecht Sharon , Santhanam Lakshmi 
Published: May 2024

Introduction: Depending on surrounding cell types, substrate mechanics, and chemical agonists, vascular cell types – including endothelial (ECs) and smooth muscle cells (VSMC) — modulate their behavior to maintain homeostasis. Aging perturbs this homeostasis resulting in EC and SMC dysfunction, marked by impaired barrier integrity and pathological ECM remodeling. Endothelial-to-mesenchymal transition (EndMT) in ECs and “dedifferentiation” of VSMCs towards a synthetic phenotype are phenomenon under investigation as cellular drivers of the widespread dysregulation seen with aging. The overall goal of this project is to understand the effect of cross-talk between ECM and growth factor signaling on vascular cell plasticity during aging. Materials and Methods: Human aortic endothelial cells (HAECs) were seeded onto transwell inserts after seven days treatment with or without TGF-β. After growing to confluence on the insert, cells were subjected to a FITC-dextran transwell assay. A parallel group of cells was seeded onto fibronectin coated glass-bottom dishes and stained for the expression of focal adhesion proteins and cell-type markers. Mouse aortic smooth muscle cells (maSMCs) were isolated from C57Bl6 mice at 3 (young), 6 (early middle-aged; EMA), 9 (middle-age; MA), or greater than 18 months of age (old). Cells were seeded onto dye-quenched (DQ) collagen type I (Col-I) substrate before gain of fluorescence was measured in proximity to the cell as well as in the surrounding media. A parallel group of cells were allowed to grow in media containing FITC Col-I, and gain of fluorescence was measured in proximity to the cells. Each cell type (3M, 6M, 9M, and 18M) in both experiments (DQ and FITC) were further treated with MMP inhibitor, TG2 inhibitor and TGF-β1 to measure their impacts on Col-I turnover. Results: Barrier function was not impaired in ECs cultured with TGF-β1, relative to their untreated counterparts. Mouse aortic SMCs isolated from older mice had decreased rates of Col-I cleavage and were more susceptible to MMP inhibition than their younger counterparts. Conclusions: maSMCs from older mice have lower Col-I turnover than their younger counterparts. This is consistent with bulk tissue behavior, as it is well known that relative collagen levels increase in the elastic vasculature as we age. TGF-β1 treatment did not have an effect on permeability of 4kd FITC-dextran, it is feasible that there will be an impact on the larger 70kd fragments. Travis Brady is supported by the NASEM Ford Foundation Pre-doctoral Fellowship. This is the full abstract presented at the American Physiology Summit 2024 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.
Antillean manatees (Trichechus manatus) tolerate acute food deprivation associated with a modest reduction in body mass
Authors: Ruiz Maria Isabel , Rivera-Pérez Carla I. , Fernández-Martínez Ricardo , Mignucci-Giannoni Antonio A. , Ortiz Rudy M. 
Published: May 2024

Acute food deprivation induces metabolic shifts toward a greater reliance on lipid metabolism to sustain homeostasis in marine mammals. Lipid utilization depends on diet, metabolic rate, environmental conditions, and food availability. Antillean manatees ( Trichechus manatus) are aquatic herbivores with two-layered fat deposits that can reduce their metabolic rate by 23% when fasting. However, the contributions of lipid metabolism during fasting and refeeding in manatees remain poorly understood. Three juvenile Antillean manatees under human care were food deprived for 64 hours under close medical watch, then refed. Body mass (BM) was measured before and after acute food deprivation over the course of the four days of the study. Plasma samples were collected 16 hours post-prandial control, 40 and 64 hours after food deprivation, and 16 hours post-re-feeding. Prior to deprivation, mean BM was 107.3 ± 5.2 kg, and 100.1 ± 4.3 kg after deprivation. LDL increased after 40 hours of fasting and decreased at 64 hours, whereas HDL peaked at 60 hours post-fast and decreased during refeeding. TG and VLDL increased after refeeding; however, there were no significant changes between deprivation and refeeding in the lipid panel suggesting that 64 hours of acute food deprivation is well tolerated. These data provide an insight to the metabolic tolerance of the Antillean manatee that may experience acute periods of food deprivation as animals migrate across habitats and/or as they experience habitat loss or seasonal food scarcity. I. Ruiz was supported by NIH NIGMS URISE grant T34 GM145511. This is the full abstract presented at the American Physiology Summit 2024 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.
Time-Restricted Feeding Mitigates Age-Related Cognitive Decline: Impacts on Neurovascular Coupling and Blood-Brain Barrier
Authors: Sanford Madison , Negri Sharon , Reyff Zeke , Ballard Cade , Nyul-Toth Adam , Gulej Rafal , Csiszar Anna 
Published: May 2024

Vascular cognitive impairment (VCI) and age-related cognitive decline are mediated by alterations in microvascular function, cerebral blood flow (CBF), neurovascular coupling (NVC) responses and blood-brain barrier (BBB) permeability. The pathogenesis of VCI can be influenced by lifestyle factors like exercise, nutrition, and dietary habits. Time-restricted feeding (TRF) offers an accessible intervention that can be employed during aging. This study is aimed at investigating the cerebromicrovascular effects of TRF on NVC responses and BBB integrity in aged mice to explore potential novel interventions against the age-related loss of cognitive function. We hypothesized that TRF would improve NVC responses and BBB integrity during aging to prevent age-related cognitive decline. To test this hypothesis, 18-month-old C57BL/6 mice were placed on TRF regimen for 6 months, where they received ad libitum feeding for 6 hours each day. 6- and 24-month-old mice fed 24 hours/day ad libitum were used as controls. All three groups were subjected to cognitive tests including radial-arms water maze (RAWM). NVC was assessed by measuring CBF using last speckle contrast imaging while performing contralateral whisker stimulation, and BBB integrity was measured through extravasation of tracers in various sizes using intravital two-photon imaging. We found that aged mice had significant impairment in NVC responses. 6 months of TRF improved BBB integrity and rescued NVC responses, and significantly improved learning and spatial memory. This study emphasizes the importance of maintaining cerebromicrovascular integrity to promote healthy brain aging and cognitive health. The establishment of the mechanisms by which TRF exerts benefits during aging provides pertinent information to the future development of therapeutic strategies to prevent VCI. Stephenson Cancer Center, National Institute of Aging R03 AG070479, American Heart Association. This is the full abstract presented at the American Physiology Summit 2024 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.
Sex Differences in Youth Elite Swimming Performance
Authors: Morgan Ashley M. , James Jessica J. , Hunter Sandra K. , Joyner Michael J. , Coleman Doriane , Senefeld Jonathon W. 
Published: May 2024

Purpose: While it is well-known that elite males are faster than elite females in all Olympic-length swimming events, less is known about the age of the divergence in swimming performance between the sexes. Thus, this observational study compared swimming performance of elite male and female youths. Methods: We collected the all-time best 100 U.S. freestyle swimming performance times of boys and girls aged 5 to 18 years for six freestyle swimming events from 50m to 1500m. We compared data using univariate ANOVAs and Chi-squared tests. Results: Swimming performance improved with increasing age for both boys and girls (p<0.001) until a plateau— which began at a younger age for girls (15 years) than boys (17 years; sex × age; p<0.001). Before age 8, there was no sex difference in swimming performance (p>0.05). Beginning at age 9 however, boys swimming performance was faster than girls (1.0% to 1.3% depending on distance), and this sex difference in performance increased in magnitude until 18 years (p<0.001; 6.6% to 11.0% depending on distance). While boys represent 50% of the top 100 age-group performances at ages 5 and 6, boys represent an increasingly larger proportion of top performances across years of age including nearly 100% of all top 100 age-group performances beginning at age 15—except for one notable female swimmer in the 1500m Conclusion: Among elite youth swimmers, boys have increasingly faster performances than girls beginning at age 9 years, with minimal sex differences in swimming performance before 9 years. Additionally, boys represent an increasingly larger proportion of the top 100 age-group performances of all-time. No funding. This is the full abstract presented at the American Physiology Summit 2024 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.
The trepidatious return to in-person instruction during the COVID-19 pandemic: valuable lessons applied from online teaching using Lt in the face-to-face classroom
Authors: Ford Bridget 
Published: May 2024

The speed at which educators have embraced new technologies during the COVID-19 pandemic has been remarkable. This pivot to virtual instruction has been particularly diffcult in courses where hands-on experiences are the norm, such as in anatomy and physiology laboratory courses. Now with the transition back to mostly in-person instruction, the anatomy and physiology lab environment has faced a new set of challenges where the want to return to a strictly hands-on experience is being met with the need to still maintain flexibility and accessibility for students placed in quarantine. The anatomy and physiology lab curriculum at the University of the Incarnate Word (UIW) has adapted to this varied set of needs by adopting the use of the web-based laboratory software platform, Lt. Students in introductory anatomy and physiology labs surveyed during strictly virtual semesters reported a high level of satisfaction with the Lt lab software. Ratings regarding ease of use, support of learning, and overall ratings increased each semester with the highest ratings occurring during the recent semesters where instruction returned to mostly in-person and hands-on (Fall 2021 – Spring 2022). Interestingly, beginning in 2022 and continuing into fall of 2023, ratings of overall satisfaction began to decrease. Although it is currently diffcult to determine the root cause of this decrease in satisfaction, we speculate that many students are becoming fatigued with the continued use of seemingly virtual labs. Although most lab exercises are hands-on and include dissections and live physiological recordings, we think that the continued use of a virtual interface is too reminiscent of learning under quarantine conditions. Even with variations in ratings regarding Lt use in our introductory anatomy and physiology laboratories, our data still help to support the widely held belief that students perform best, and that instruction is more effective with face-to-face laboratory courses. With our continued use of Lt, we have found an effective combination of virtual and in-person instruction that best fits our course outcomes while still supporting the flexibility and accessibility our students require. Research reported in this poster was supported by the University of the Incarnate Word Offce of Research and Graduate Studies. This is the full abstract presented at the American Physiology Summit 2024 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.
Anabolic Signaling After Withdrawl of AMPK-Activating Drugs in C2C12 Cells
Authors: Dray Steven D. , Summers Abigail E. , DePierro Ethan A. , Johnson Kade G. , Thomson David M. 
Published: May 2024

Adenosine monophosphate-activated protein kinase (AMPK) is a master metabolic regulator that is activated under low-energy conditions, which generally promotes catabolic processes, including an increase of ATP synthesis and inhibiting anabolic processes that consume ATP. Indeed, acute AMPK activation potently inhibits anabolic pathways, including Akt/mTORC1 signaling. However, recent research reported that withdrawal of the AMPK-activating drug AICAR after a short treatment period results in enhanced anabolic signaling through Akt/mTORC1. This work aims to extend those findings using a more specific AMPK activator since AICAR is well-known to have numerous AMPK-independent effects. To do so, we treated differentiated C2C12 cells with either 2 mM AICAR, 5uM MK8722 (a pan-AMPK activator), or vehicle control (DMSO) for 60 minutes. After 60 minutes of incubation with the drugs, the treatment media was removed, the cells were rinsed and lysed immediately or incubated with media without drug treatment for 30, 60, 120, or 180 minutes, and then lysed. Phosphorylation of ACC (as an indicator of AMPK activity) and anabolic markers Akt, p70 ribosomal protein S6 kinase (S6k), and eIF4E-binding protein (4EBP1) were measured by western blotting. ACC phosphorylation (reflective of AMPK activity) remained elevated through 180 minutes after drug withdrawal for both AICAR and MK8722. Both AKT and S6k phosphorylation remained suppressed for at least 60 minutes after withdrawal of both AICAR and MK8722 and were not elevated at any time point up to 3 hours after withdrawal of the drugs. In contrast to previously reported data, we conclude that anabolic signaling remains inhibited in skeletal muscle myotubes for up to 3 hours after 1 hour of pharmacological activation of AMPK. This work was funded by a BYU Gerontology Grant. This is the full abstract presented at the American Physiology Summit 2024 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.
Sex Differences in Exercise-Induced Modulation of the Humoral Immune Response to Influenza Vaccination
Authors: Fink Ashley , Bock Hannah , Colleran Jack , Hinson Destin , Campos Manuel 
Published: May 2024

Physical activity is known to modulate immune cell function and understanding its role in vaccine-induced immunity is critical for both optimizing vaccine strategies and implementing lifestyle factors that contribute to better immune health. This study aimed to elucidate the impact of physical activity on antibody responses following influenza vaccination, with a specific focus on biological sex differences among male and female cross-country athletes. Based on previous studies, we hypothesized that physical activity would increase immune responses, regardless of biological sex. Two cohorts of male and female Division III college cross-country runners and two cohorts of non-athletes (no physical activity) participated in this longitudinal investigation. Studies were conducted in two separate influenza seasons where participants received a quadrivalent seasonal influenza vaccine (2020-21 and 2022-23). An estimated non-adjusted VO2 max was calculated, and a survey was administered to identify overall health status prior to the start of the study. Blood samples were collected at predefined intervals to assess pre- and post-vaccination antibody responses specific for the H1N1 component of each seasonal influenza vaccine. VO2 max, a measure of overall fitness, was higher in the athletes as compared to those participants who were not physically active, and these results were consistent among both males and females. All participants mounted an immune response to the seasonal influenza vaccine as indicated by a rise in vaccine-specific antibody titers from pre-vaccination to post-vaccination. However, the differences in titers were sex specific, with greater neutralizing antibody titers in females as compared to males — regardless of their level of physical activity. When data were further partitioned by physical activity level, it was identified that although males have lower antibody responses than females, males that were cross country runners had significantly greater antibody responses than males that were not physically active. This study contributes valuable insights into the complex interplay between exercise, sex, and immune responses. Understanding these dynamics could inform recommendations for individuals to be engaged in regular physical activity to optimize overall immune health. This research was funded by a College of Saint Benedict and Saint John's University Faculty Development and Research Committee Award. This is the full abstract presented at the American Physiology Summit 2024 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.