bluuebunny/crossref_metadata_2025 huggingface dataset:
GCPII Inhibition in Macrophages Delays Age-related Muscle Atrophy in Mice
Authors: Su Yu , Tallon Carolyn , Thomas Ajit , Huizar Kaitlyn , Huang Meixiang , Tenora Lukas , Liyanage Wathsala
Published: May 2024

Age-related loss of muscle mass and strength (Sarcopenia) significantly impairs quality of life in the elderly, yet lacks effective treatments. We previously demonstrated that inhibition of GCPII delayed muscle function decline and neuromuscular junction (NMJ) denervation in an amyotrophic lateral sclerosis (ALS) animal model. As sarcopenia shares NMJ deterioration with ALS, we tested the potent GCPII inhibitor 2-(phosphonomethyl)-pentanedioic acid (2-PMPA) in aging mice, and found that it also preserved muscle function and NMJ integrity. By immunofluorescent staining, we demonstrated that aged mice muscles were associated with GCPII-positive infiltrating macrophages. We next developed a macrophage-targeting GCPII inhibitor delivery system by covalently attaching 2-PMPA to 4th-generation polyamidoamine (G4-PAMAM) dendrimers (D-2-PMPA). The D-2-PMPA was found to inhibit GCPII with IC50= 3.50±0.05 nM. Aged mice muscle showed increased GCPII activity specifically in CD11b+ enriched macrophage cells (138.6±3.0 vs. 336.6±52.9; p<0.05) but not in CD11b− cells. Systemic D-2-PMPA therapy (20 mg/kg 2-PMPA equivalent; IP 3 × /week) completely inhibited the elevated GCPII activity (336.5±52.8 vs. 21.8±9.2 fmol/mg/h; p<0.001). 5-months of D-2-PMPA therapy initiated with 15-month-old mice significantly preserved calf muscle volume (95.0±0.8% vs. 90.4±0.7%; p <0.001), enhanced isometric force (230.2±13.3 vs. 184.0±9.0 mN, female p<0.05; 257.3±21.0 vs. 189.7±19.3 mN, male p<0.05), improved grip strength (96.1±1.6 vs. 90.2±2.2 % of maximum p<0.001) and increased rotarod latency (119.0±6.6 vs. 93.5±9.3 s, female p<0.05; 104.5±5.2 vs. 79.3±4.2 s, male p<0.001). Age-related decline of nerve signal conductivity to muscles was also delayed with D-2-PMPA as observed by improved compound muscle action potential (CMAP) latency (1.28±0.02 vs. 1.38±0.04 ms; p< 0.05) and amplitude (15.2±0.5 vs. 1.27±0.6 mV; p<0.01). Furthermore, NMJ integrity was preserved with treatment as demonstrated by single fiber jitter (5.4±0.3 vs. 7.5±0.5 μs; p<0.01). Overall, our current results support that excessive GCPII activity in muscle macrophages is associated with age-related muscle atrophy, which is improved by GCPII inhibition. This study highlights GCPII inhibition in macrophages as a new therapeutic approach to delay sarcopenia.

R01AG078181, R01AG068130, R01NS093416.

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.
Estrogenic re-mapping of the metabolic response to an energy deficit
Authors: Vander Paul , Park Jae , Correa Stephanie
Published: May 2024

Endothermy is an adaptation that can be traced back hundreds of millions of years and is critical for nearly every aspect of mammalian biology. Despite the advantages associated with a stable internal temperature, endothermy is energetically expensive. To conserve energy when food is scarce, mice have evolved the ability to reversibly enter a regulated state of hypothermia and hypometabolism, known as torpor. We have found that circulating 17β-estradiol, a potent estrogen, inhibits fasting-induced torpor in ovariectomized female mice, yet the signaling mechanisms underlying this estrogenic re-mapping of the metabolic response to an energy deficit remain largely unknown. Recent studies have identified the medial preoptic area of the hypothalamus (MPO) as the central regulator of torpor. MPO neurons that express estrogen receptor alpha have been identified as central coordinators of torpor, and MPO neurons that are activated during torpor broadly express estrogen receptors, suggesting that circulating estrogens may directly modulate torpor-driving neurons in the MPO. To test the hypothesis that circulating estrogens inhibit torpor by acting directly on estrogen-sensitive neurons in the MPO, we delivered 17β-estradiol (E2) directly to the MPO before inducing torpor with a 48-hour fast. Surprisingly, we found that E2 delivered to the MPO was suffcient to inhibit fasting-induced torpor in gonad-intact, but not ovariectomized, female mice. These data demonstrate that E2 signaling in the MPO is insuffcient to inhibit torpor on its own and that there are likely MPO-independent nodes in the body that circulating estrogens act on to inhibit torpor. However, our data also demonstrate that E2 signaling in the MPO does play a role in tuning the torpor response when endogenous gonadal hormones are present, suggesting that the MPO can sense estrogens and engage the appropriate effector circuits to inhibit torpor in certain physiological contexts. Together, these data advance our understanding of how circulating estrogens inhibit torpor in mice — a critical step towards the broader goal of understanding how circulating estrogens influence energy expenditure, and how these pathways can be manipulated to improve metabolic health.

NIH RO1 (R01AG066821) - "Estrogenic modulation of neural circuits that control temperature" AHA Predoctoral Fellowship (23PRE1019923) - Estrogenic modulation of hypothalamic neurons that control energy expenditure.

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.
Exercise may be a Novel Strategy to Reduce Vascular Toxicity of Immune Checkpoint Inhibitors in a Mouse Melanoma Model
Authors: Lee Jonghae , Pareek Sumedha , Ballarò Riccardo , Savage Hannah , Patel Hetal , Ko Kyung-Ae , Abe Jun-ichi
Published: May 2024

Background: Immune checkpoint inhibitors (ICIs) are a cornerstone in advanced melanoma treatment. Unfortunately, ICI-associated cardiovascular toxicity, particularly atherosclerotic events, poses a significant challenge. Identifying interventions to mitigate the cardiovascular toxicity of ICI is critical for enhancing the quality and duration of life in cancer survivors. Given the established benefits of exercise in atherosclerosis prevention, this study explores its potential to reduce ICI-induced vascular toxicity in the context of melanoma. We hypothesized that aerobic exercise would decrease ICI's vascular toxicity in a mouse melanoma model. The primary experimental outcome was endothelial mesenchymal transition (EndMT), an early atherosclerosis indicator. Methods: C57BL/6 mice were subcutaneously injected with 0.8 x 106 BP melanoma cells ( BrafV600E/WT and Pten−/−). Upon tumor palpability, mice were assigned into four groups: IgG, Exercise, anti-PD-1, and anti-PD-1+Exercise. Mice were treated with bi-weekly administration of anti-PD-1 or IgG antibody (150 μg) for three weeks, combined with or without treadmill exercise (12 meters/minute for 45 min per day, five days/week). Body weight was monitored weekly. Following the final treatment, aortic tissues were collected and en face immunofluorescence staining for endothelial marker VE-cadherin (VE-Cad) and vimentin was performed to assess EndMT, then analyzed via confocal microscopy. Results: No significant weight differences were observed between groups. Notably, the EndMT marker vimentin expression was significantly higher in anti-PD-1 treated tumor-bearing mice compared to IgG controls (3.8% vs 0.6%, p=.03) in the atheroprotective laminar flow area. This was reduced by exercise; the anti-PD-1+Exercise group showed significantly reduced endothelial vimentin levels relative to the anti-PD-1 alone (0.8% vs 3.8%, p=.04). Disturbed flow areas did not exhibit notable differences between any group. Conclusions: Aerobic exercise may be protective against vascular toxicity in mice treated with ICIs by promoting atheroprotective flow and potentially inhibiting EndMT. Although these initial results are promising, comprehensive studies are required to ascertain the impact of exercise on preventing ICI-induced EndMT and subsequent atherosclerosis in this mouse melanoma model. Future research will aim to more deeply characterize the process of EndMT following ICI treatment and evaluate the preventive capacity of exercise against atherosclerosis in this context.

MD Anderson Cancer Center Melanoma SPORE grant (NCI P50CA221703-05).

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.
Diminished insulin-induced vasodilation of the posterior cerebral artery in db/db mice is associated with reduced presence of endothelial insulin receptor alpha and inward remodeling
Authors: Lazo-Fernandez Yoskaly , Padilla Jaume , Martinez-Lemus Luis A.
Published: May 2024

Type 2 diabetes (T2D) is a major risk factor for cardiovascular disease (CVD) development and associated mortality. In the cerebral circulation, T2D-related vascular disfunction also contributes to diverse cerebrovascular diseases including stroke, cognitive impairment, and dementia. Previous research has documented that endothelial dysfunction and inward remodeling are prevalent pathophysiological characteristics of the arterial circulation in T2D. We have further documented that reduced presence of endothelial insulin receptor alpha (IRα) contributes to impaired insulin-dependent vasodilation in omental arteries from T2D patients. Herein, we tested the hypothesis that, compared to wild-type (WT) mice, diabetic db/db mice have reduced insulin-induced vasodilation of the posterior cerebral artery (PCA) in association with reduced presence of endothelial IRα and inward remodeling. We used pressure myography in isolated PCAs to assess vascular reactivity and remodeling, and confocal microscopy to determine IRα content on the endothelial surface. All reported differences are significant at P<0.05. Our results indicate that, when compared with WT controls, PCAs from db/db mice have reduced insulin-induced vasodilatory responses in association with reduced presence of endothelial IRα, inward remodeling, and increased arterial stiffness. The amount of IRβ, elastin, or collagen present in the PCAs did not differ between groups. These findings provide evidence of cerebrovascular endothelial dysfunction in the form of impaired insulin-induced vasodilation in db/db mice, a defect likely attributed to the reduced presence of endothelial IRα and associated with vascular inward remodeling. These changes may contribute to cerebrovascular disease development and progression in T2D, including stroke, cognitive impairment, and associated dementias.

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.
P311 Influences Macrophage Polarization
Authors: Boddupally Sreenu , Kasaram Pavana Jyotsna , Badri Kameswara
Published: May 2024

Obesity is a pandemic disease that has become a serious concern worldwide. In United States, recently self-reported obesity rates of adults were escalated to 40%. In the early phase of obesity, excessive macrophage infiltration and disequilibrium of macrophage phenotypes (M1 vs. M2 or vice versa) play a critical role in the microenvironment of adipose tissue. It often leads to chronic inflammation and is a major cause for metabolic disorders including insulin resistance, type-2 diabetes, and cardiovascular diseases. P311 is an intrinsically disordered protein, contributes to adipogenesis as transcription regulator through activation of PPARγ2, master regulator of adipogenesis. However, the P311 role on the macrophage polarization was not known. Here we studied the macrophage polarization in presence of P311 using Raw 264.7 cells. Raw cells were treated with either interleukin-4 (IL4) or lipopolysaccharide (LPS) for macrophage polarization towards M2 and M1 phenotype respectively in presence and absence of P311 overexpression. Macrophage phenotypic switch was assessed using CD206 (M2 marker) and CD86 (M1 marker) expression. The dose and time dependent effects of IL4 and LPS on the expression of P311 and macrophage markers was also studied. A significant increase in endogenous P311 expression observed with IL4 treatment whereas LPS treatment showed the opposite effect. Our findings showed that the P311 overexpression promotes anti-inflammatory macrophage phenotype (M2) as indicated by the significant increase in mRNA and protein expression of CD206 when compared to empty vector (EV, pCMV) transfected control group. Further, P311 overexpression in LPS treated RAW cells significantly increased the expression of CD206, on contrary to the classical M1 polarization of LPS, compared to EV transfected cells. In addition, P311 suppressed the expression of CD86 there by facilitating macrophage switch towards anti-inflammatory phenotype in presence of LPS treatment. IL4 treatment alone increased macrophage activation towards M2 phenotype however IL4 treated P311 overexpressed cells showed further increase in CD206 expression compared to EV transfected cells. Our studies indicate that the P311 expression plays an important role in promoting macrophage polarization toward M2 phenotype.

This study was supported by research funding to KB, from NIH/NIGMS #SC1GM141937.

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.
Acute Exercise Alters Skeletal Muscle DNA Methylation in Sedentary Participants
Authors: Zapata Bustos Rocio , Reed Baylee L. , Coletta Richard L. , Garcia Luis A. , DeFilippis Eleanna , Roust Lori R. , Funk Janet L.
Published: May 2024

Skeletal muscle is a highly plastic tissue, adapting its structure and metabolism in response to various stimuli like exercise. This study aimed to determine the plasticity of skeletal muscle DNA methylation in response to an acute exercise bout in volunteers with a range of insulin sensitivities. We studied 14 sedentary participants (7 male/7 female): age = 34.5 ± 3.1 years, body mass index = 29.3 ± 1.9 kg/m2 and HbA1c = 5.3 ± 0.1 %. We performed VO2peak tests to determine exercise capacity (VO2peak = 25.5 ± 1.6 mL per Kg per minute) and euglycemic hyperinsulinemic clamps (Rd value = 5.9 ± 0.8 mg per Kg per minute) with vastus lateralis muscle biopsies before and 30 minutes after a single 48-minute exercise bout. We extracted DNA from the muscle biopsies and performed reduced representation bisulfite sequencing. After performing quality control on the sequencing data, 1,034,947 sites were included for downstream analyses. MethylSig analysis revealed 17,030 differentially methylated cytosines (DMC), 9,020 increased and 8,010 decreased. To identify biologically meaningful DMCs, we used a mean change of >10%, which resulted in 1,179 and 1,436 increased and decreased sites, respectively. Pathway analysis of the increased DMCs revealed an enrichment in efferocytosis, leukocyte transendothelial migration, and FOXO-mediated transcription of oxidative stress pathways. In addition, pathway analysis of the decreased DMCs revealed an enrichment in metabolic (type 2 diabetes/ PI3K-Akt signaling), actin cytoskeleton, integrin/extracellular matrix and calcium signaling pathways. Our study reveals that an acute exercise bout induces alterations in the DNA methylation of skeletal muscle, impacting specific pathways in individuals with varying degrees of insulin sensitivity. Notably, our findings underscore the remarkable plasticity of skeletal muscle tissue.

This research was funded by the National Institutes of Health, grant number R01DK094013 (Dawn Coletta).

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.
TMEM16A in smooth muscle cells acts as a pacemaker channel in the internal anal sphincter
Authors: Lu Ping , Lifshitz Lawrence , Bellve Karl , ZhuGe Ronghua
Published: May 2024

Maintenance of fecal continence requires a continuous or basal tone of the internal anal sphincter (IAS). Paradoxically, the basal tone results largely from high-frequency rhythmic contractions of the IAS smooth muscle. However, the cellular and molecular mechanisms that initiate these contractions remain elusive. Here we show that the IAS contains multiple pacemakers. These pacemakers spontaneously generate propagating calcium waves that drive rhythmic contractions and establish the basal tone. These waves are myogenic and act independently of nerve, paracrine or autocrine signals. Using cell-specific gene knockout mice, we further found that TMEM16A Cl− channels in smooth muscle cells (but not in the interstitial cells of Cajal) are indispensable for pacemaking, rhythmic contractions, and basal tone. Our results identify TMEM16A in smooth muscle cells as a critical pacemaker channel that enables the IAS to contract rhythmically and continuously. This study provides cellular and molecular insights into fecal continence.

R01HL139686 and R21HD097458.

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.
Ca2+-dependent contractile signaling induced by dsDNA-cGAS ligation mediates type 1 interferon generation and vascular injury
Authors: Joshi Bhagwati , Joshi Jagdish Chandra , Balaji Raghunath Rao Vijay Avin , Banerjee Somenath , Yadavalli Tejabhiram , Shukla Deepak , Mehta Dolly
Published: May 2024

Acute Lung injury (ALI) is an uncontrolled systemic inflammatory response from bacterial or viral infection. The cyclic GMP-AMP synthase (cGAS) detects cytosolic double stranded DNA (dsDNA) release from bacteria, viruses, or apoptotic cells and induces innate immunity by generating the second messenger cGAMP and activation of stimulator of interferon genes (STING). However, the mechanisms regulating cGAS activity upon binding dsDNA remain elusive. Here, we show for the first in-depth analysis of mechanisms inducing cGAS activation in using lung endothelial cells (EC) and establish its translational relevance in causing ALI using a mouse model. We show that within 15 min, dsDNA ligation with cGAS mediates its interaction with a motor protein, myosin light chain 6 (MYL6), leading to phosphorylation of MLC and actin stress fiber formation. cGAS-MYL6-mediated MLC phosphorylation required calcium release and organization of an ER-Ca2+ sensor, Stromal Interaction Molecule 1 (STIM1) as puncta. Activated STIM1 also induced cGAS tyrosine phosphorylation at Y215/242 residues via cSrc. Interfering with MYL6 or cSrc expression impaired cGAS condensation and cGAMP generation. Liposome delivery of phosphodeficient cGAS (Y215/Y242àF215/F242) in EC of cGAS null mice blocked type1-IFN production during bacterial pneumonia. Our finding suggests that STIM1 is crucial in inducing cGAS activity and type1-IFN production. cGAS thus represents a novel target for inhibiting STING activation, thereby suppressing tissue injury and inflammation.

NIH.

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.
Enhancing Physiology Education Through Physiological Simulation
Authors: Fong Angelina , Kim Phillip , Rathner Joseph
Published: May 2024

Advances in Physiology Education began publishing papers in 2005, using classic papers in physiology teaching [1]. This approach has several valuable outcomes: Classic experiments, conclusion of which form the foundation of much of our undergraduate teaching textbooks, require less specialized knowledge to understand and interpret the data and conclusions. It demonstrates the scientific method, demonstrating both "what do we know" and "how do we know." It promotes inquiry-based learning. It fosters data literacy, teaching students to interpret graphs and provides historical context for physiology [1]. Traditional practical classes achieve many of these outcomes while also providing a tactile experience, and have added benefits to students’ data literacy — in as much as the students perform the protocols themselves. Students will gain insight to what “squiggly lines” on a screen are measuring and the individual variability in what raw physiological recordings look like. Students will gain a greater appreciation for analytical techniques, and the manipulations and analysis that needs to be performed to interpret data. Students also gain an appreciation of the difference between textbook vs real data. Nevertheless, in person practical classes have limitations due to resource intensity, including space, materials, and curriculum time. HumMod (hummod.org) is a freely available mathematical model of Human Physiology, a "time-dependent physiologic simulation engine" [2]. JustPhysiology (justphysiology.com) is an education-focused web interface for HumMod [3]. We have written four physiology-based workshops utilizing simulated data from JustPhysiology. The JustPhysiology workshops were setup as a structured inquiry activity where students are expected to apply their content knowledge to interpret data, and students submitted their reports after each workshop for evaluation and feedback. In preparing the workshop activities for deployment, we trialed the activities with students who had previously completed our second year Human Physiology subject (and were thus familiar with the content). We then engaged students in focus group interviews —ascertaining the students’ perceptions of the learning experience. The outcome of the focus group interview suggests that students engaging with the workshop tasks enter into a positive learning cycle:

[Formula: see text]

The spontaneous emergence of a learning cycle, promoting deeper understanding of the physiology suggests that these data driven workshops will have improve student learning in Human Physiology. References:DOI: 10.1152/advan.00031.2005; DOI: 10.1146/annurev-bioeng-082219-051740; DOI: 10.1016/j.morpho.2019.09.004.

University of Melbourne FlexAP initiative.

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.
Genetic modification of cardiac fibroblasts in adult rats using adeno-associated virus serotype 9
Authors: Nieto Bridget , Cypress Michael , Chandran Sanjana , Dugan Matthew , O-Uchi Jin , Jhun Bong Sook
Published: May 2024

Cardiac fibrosis is a process involving pathological extracellular matrix remodeling as well as cardiac fibroblast (CF) activation in response to cardiac injury and stress, which is frequently associated with cardiac dysfunction. Therefore, understanding the molecular mechanisms underlying CF activation is critical to develop successful therapies for treating cardiac fibrosis. CF-specific gene modifications in mouse models have been reported as key tools for cardiac fibrosis research. Although rat cardiac disease models also offer many of the same advantages as the mouse models, there are no rat models that employ CF-specific conditional gene modification. Here, we attempted CF-specific gene introduction in rats using adeno-associated virus serotype 9 (AAV9), allowing us to develop fast and simple rat cardiac disease models rather than establishing transgenic rat lines. AAV9 carrying a CF-specific human TCF21 (hTCF21) promoter and a transgene of interest was generated and introduced into adult rats via tail vein injections. Since we previously reported in cultured CFs that protein kinase D (PKD) activation at the outer mitochondrial membrane (OMM) induces mitochondrial fragmentation via phosphorylation of a mitochondrial fission protein DRP1, we generated an OMM-targeted dominant-negative mutant of PKD (termed mt-PKD-DN) to specifically inhibit PKD activity at the OMM in CFs in vivo. In vivo cardiac function, gene expression, protein expression, and mitochondrial morphology were assessed 2-10 weeks after AAV9 injection by echocardiography, quantitative RT-PCR, immunohistochemistry, and transmission electron microscopy (TEM), respectively. AAV9-hTCF21-injected rats maintained normal cardiac dimensions and contractile function compared to aged-matched control rats. Using AAV9-hTCF21-EGFP, we confirmed organ-specific (i.e., heart) and cell type-specific (i.e., CF-specific) expression of GFP. Next, we injected AAV9-hTCF21-mt-PKD-DN or -luciferase (Luc) as a control in adult rats. TEM images from fixed rat ventricular tissues revealed a significant increase in mitochondrial aspect ratio and mitochondrial perimeter in CFs with AAV9-hTCF21-mt-PKD-DN compared to AAV9-hTCF21-Luc, indicating that PKD inhibition at the OMM induces mitochondrial elongation in CFs in vivo. In contrast, no significant change in mitochondrial morphology was observed in the cardiomyocyte area. In summary, we successfully achieved a CF-specific gene delivery to the adult rat hearts in vivo, demonstrating the potential of a simplified CF-specific rat transgenic model using the AAV9-hTCF21 system.

NIH/NHLBI R01HL160699.

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.
Fiber type specific myonuclear and satellite cell content comparisons between the vastus lateralis and soleus muscles in humans
Authors: Boyd Gerard , Skiles Chad , Robbins Ethan , Gouw Aaron , Minchev Kiril , Ryder Jeffrey , Ploutz-Snyder Lori
Published: May 2024

Objectives: The purpose of this study was to compare fiber type specific myonuclear and satellite cell number of the vastus lateralis and soleus muscles in humans. Hypotheses: Myonuclear number (MNN), myonuclear domain (MND), and satellite cell number (SCN) would be similar within each fiber type between the vastus lateralis and soleus. Methods: Muscle biopsies from the vastus lateralis and soleus of 24 individuals (34±7y, 24-55y) were sectioned, immunofluorescently stained, and analyzed for MNN, MND, and SCN in slow (myosin heavy chain (MHC) I) and fast (MHC IIa) muscle fibers. SCN was determined only in MHC I fibers for the soleus. MNN and MND were compared for 24 individuals, while SCN was compared for 19 individuals. Results: MNN was similar in MHC I (3.32±0.81 vs. 3.66±0.65 myonuclei/fiber, P=0.067) and IIa (3.63±0.82 vs. 3.83±0.68 myonuclei/fiber, P>0.05) fibers of the vastus lateralis and soleus. Similarly, MND was not different in MHC I (1649±305 vs. 1673±340 μm2/myonuclei, P>0.05) and IIa (1705±313 vs. 1819±394 μm2/myonuclei, P>0.05) fibers of the vastus lateralis and soleus. However, SCN was 62% higher (p<0.05) in MHC I fibers of the soleus (0.127±0.039 satellite cells/fiber) compared with MHC I fibers of the vastus lateralis (0.083±0.024 satellite cells/fiber). Conclusions: The literature is void of comparisons of myonuclei and satellite numbers across different human muscles. These initial results suggest myonuclear number and the area “governed” by each myonuclei (i.e., the myonuclear domain) appears to be similar within the two main fiber types found in the vastus lateralis and soleus muscles. Interestingly, within the same slow fiber type (i.e., MHC I fibers) across these two muscles, it appears the soleus is programmed to have a substantially higher satellite cell content. The basis for this intrinsic difference in slow myofiber satellite profile may be related to the differences in daily myocellular activity between the vastus lateralis and soleus.

This research was supported by the National Aeronautics and Space Administration, NNJ06HF59G; the Institute for Translational Sciences at the University of Texas Medical Branch, supported in part by a Clinical and Translational Science Award (UR1TR000071) from the National Center for Advancing Translational Sciences, National Institutes of Health; the NASA Flight Analogs Project; and the Human Bioenergetic Program at Ball State University.

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.
Mitochondrial involvement in the metabolic defects evoked by hepatocyte-specific BBSome deficiency
Authors: Guo Deng F , Zhao Yuying , Rouabhi Younes , Rahmouni Kamal
Published: May 2024

The BBSome, a protein complex of 8 Bardet-Biedl syndrome (BBS) proteins including BBS1, has emerged as an important regulator of metabolic function. BBSome deficient human and mice display several metabolic features including obesity and type 2 diabetes. Here, we show that mice lacking the BBSome specifically in liver which were generated by crossing the Bbs1fl/fl mice with liver-specific (albumin) AlbCre mice exhibit significantly higher lipid droplets in liver, by Oil Red-O staining, and in primary cultured hepatocytes (5.7%±0.4% vs 2.4%±0.6%, control), and by Transmission electron microscope (TEM). AlbCre/Bbs1flox also have elevated fasting glucose (169± 14 vs 136±8 mg/dL, p<0.05) and impaired insulin sensitivity. In addition, insulin-induced activation of AKT was significantly decreased in the liver (2.6±0.07 vs 6.6± 0.34 AU, p<0.05), but not in white adipose tissue and skeletal muscle, of AlbCre/Bbs1flox mice. Using immunohistochemistry, we found that insulin receptor level in plasma membrane was decreased by 24.2±6.8% in primary cultured hepatocytes derived from AlbCre/Bbs1flox mice which explains the insulin resistance. Our previous work implicating the BBSome in the regulation of mitochondria led us to hypothesize that mitochondria dysfunction contributes to the development of metabolic defects in AlbCre/Bbs1flox mice. TEM studies revealed that mitochondria were significantly larger and longer in hepatocytes of AlbCre/Bbs1flox mice than controls. This was associated with decreased levels of Dynamin-related protein 1 (DRP1), which critically regulates mitochondrial function through fission. Next, we asked whether the mitochondrial defects may explain the insulin receptor mistraffcking in BBSome deficient hepatocytes. To test this, hepatocytes were infected with feline immunodeficiency virus that express an active mutant form of DRP1 (FIV-DRP1S637A). Interestingly, insulin receptor localization in the plasma membrane was significantly higher in hepatocytes of Bbs1fl/fl/AlbCre­ mice infected with FIV-DRP1S637A pointing to mitochondrial defects as the underlying cause of insulin receptor mislocalization induced by hepatic BBSome deficiency. Taken together, these findings demonstrate that BBSome regulation of metabolic function involve mitochondria.

NIH and VA.

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.
LLM-Generated Multiple Choice Practice Quizzes for Pre-Clinical Medical Students; Use and Validity
Authors: Berman Jonathan , McCoy Lise , Camarata Troy
Published: May 2024

Multiple choice questions (MCQs) are frequently used in medical education, and practice questions are commonly requested by students. Automated generation of MCQs in board-exam format would potentially save significant time for faculty and generate a wider set of practice materials. The goals of this study were to explore the feasibility of using ChatGPT by OpenAI to generate USMLE/COMLEX style practice quiz items as study aids, and to analyze how and to what extent medical students would voluntarily use these quiz items to prepare for exams. Researchers gave second year medical students studying renal physiology access to a set of practice quizzes with chatGPT generated questions. The number and timing of click throughs to the quizzes, number of question attempts, and scores of completed quizzes were anonymously recorded by custom quiz software. Practice questions were accessed 15,245 times by a class of 399 students. The majority of quiz click throughs occurred in the time immediately preceding exams. To analyze the quality of exam items, they were evaluated by independent experts for quality and adherence to USMLE/COMLEX guidelines. These results demonstrate the feasibility of LLM-generated practice questions in medical education when supervised by a human faculty.

Supported By a Grant from the New York Institute of Technology Emerging Technology Group.

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 ‘12 Problem’ Revisited
Authors: Anderson Curt , Stephens Trent
Published: May 2024

Ask nearly any high school, college or graduate level health professional student how many cranial nerves there are, and the classic response is well known and not correct. Most of us know the long-held problem, the inaccurate textbooks, and are tired of saying ‘well, yes, but not really; memorize them anyway’. Its disingenuous, and we’re weary of the differences between textbook and reality. Here we provide a brief overview of how we historically arrived, a description of what it should be and a solution. This proposal results in 14 cranial nerves, doesn’t upset the numbering system and is easily adoptable and in agreement with Terminología Anatómica.

none.

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.
Riding for Focus as a Pathway to Improved Mental Health in Middle School Students
Authors: Murillo Starla , Dementyev Fletcher , Bello-Soto Benjamin , Wilson Hunter , Philipsheck Ashtyn , Bhatt Eshan , Madison Kai
Published: May 2024

Youth mental health remains in a critical state even in a post-COVID pandemic world. Exercise is a well-regarded method to boost mental health and well-being in all age groups. The Riding 4 Focus (R4F) program is a cycling education program designed to equip students with basic cycling handling skills and introduce students to the lifetime physical activity of cycling. A secondary outcome of this program is to improve the behavioral health and well-being of adolescents in middle schools, primarily aged 10-14. The current study examined associations between participating in the R4F program and mental health and well-being in those with specific unmodifiable risk factors including gender, socioeconomic, and racial identity. Anonymous online surveys were collected from 3924 adolescent participants before the R4F program and 3289 students after the cycling program across 31 schools during the fall 2021 and spring 2022 semesters. Psychosocial well-being was quantified using the WHO-5 and PSC-17-Y metrics. Using non-parametric test statistics, the data shows a significant increase in the mental health and well-being of participants after the program. Further analysis revealed that participation in the R4F program was associated with improved psychological health and well-being of minority and low-income adolescents, as well as protective associations for both genders. Although these findings are encouraging, the effcacy of the program depends on a number of factors, and future studies are needed to assess causality.

Outride, Loma Linda University School of Medicine, University of Redlands Summer Research Program, P20MD006988.

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.
Effect of Acute Isometric Handgrip Exercise on Vascular Function in Children and Emerging Adults with Congenital Heart Disease
Authors: Khan M. Rafique , Boyes Natasha G. , Luchkanych Adam M.S. , Al-Mouaiad Al-Azem Ibrahim , Jurrissen Thomas J. , Erlandson Marta , Wright Kristi D.
Published: May 2024

Endothelial dysfunction is common in congenital heart disease (CHD). Isometric handgrip (IHG) exercise may improve endothelial function; however, whether this applies to patients with CHD is unknown. We investigated brachial artery flow-mediated dilation (FMD) pre- and post- acute IHG exercise using duplex ultrasound in CHD and healthy controls (CTL; n=19 (7 F) vs. 21 (9 F), age: 13±4 vs. 13±4 y). Whereas IHG improved mean FMD in controls, it had no effect on the mean FMD response in patients with CHD. Subsequently, participants within each group were categorized based on ΔFMD response (post-pre IHG FMD), in which those that experienced a decrease were classified as non-responders (NRESP) and those that experienced an increase were classified as responders (RESP). Among NRESP, ΔFMD was lower in CHD vs. controls ( p=0.0224). Among RESP, ΔFMD was lower in CHD vs. controls ( p=0.0543). Data during pre-occlusion in NRESP from pre- to post-IHG exercise showed improved antegrade shear rate (condition effect, p=0.0078), retrograde shear rate (interaction effect, p=0.0410), and oscillatory shear index (interaction effect, p=0.049) in CHD compared to controls. Potentially, IHG exercise enhanced vascular sensitivity to shear, resulting in an increase in baseline diameter and reduced FMD in CHD NRESP. Thus, reduced FMD after acute IHG exercise is influenced by improvements in resting shear rate parameters in patients with CHD.

Saskatchewan Health Research Foundation, Heart and Stroke Foundation of Canada.

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.
Incomplete reverse remodeling in aged mice exposed to pulmonary hypertension-induced right ventricular failure
Authors: McNair Benjamin , Azmerin Maria , Thornburg Joshua , Bhavsar Vaishnavi , Matthews Julian , Bruns Danielle
Published: May 2024

Right ventricle (RV) function is the strongest predictor of survival in pulmonary hypertension (PH) and age-related HF; however no therapies exist to improve RV function. Understanding mechanisms by which the RV undoes pathological remodeling (reverse remodeling) might aid in identifying therapies for this unmet need. Our objective was to determine whether the aged RV can undergo reverse remodeling following pathological afterload (PH). We hypothesized that return to normoxia after hypoxia-induced PH would result in attenuation of RV mass and improved RV function. We exposed male and female aged (~18 months) C57Bl6 mice to hypobaric hypoxia (HH) for 4 weeks before returning them to normoxia for 3 (WK3RR) or 6 (WK6RR) weeks. HH induced RV hypertrophy by RV myocyte area which was attenuated at Wk3RR and WK6RR in both male (Con: 425 μm2 ± 104, HH: 740 μm2 ± 125, WK3RR: 447 μm2 ± 129, WK6RR: 530 μm2 ± 187) and female mice (Con: 340 μm2 ± 116, HH: 770 μm2 ± 35, WK3RR: 516 μm2 ± 186, WK6RR: 655 μm2 ± 224). HH stimulated fibrosis by collagen deposition that was also reversed during normoxia re-exposure in male mice only (Con: 4.1% ± 1.0, HH: 10.8% ± 0.8, WK3RR: 4.2% ± 0.8, WK6RR: 2.5% ± 0.7). However, HH decreased RV systolic function by fractional area change (FAC) that was also not rescued by normoxia re-exposure. The aged RV can undergo morphological reverse remodeling in response to HH; however RV function does not improve with resolution of afterload. Further investigation into the mechanisms of reverse remodeling may identify potential drug therapies for maladaptive RV remodeling.

AHA-Predoctoral Fellowship 897622 (BDM).

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.
Co-transplantation of hiPSC-Derived Mesenchymal Stem Cells and Cardiomyocytes Enhances Cardiac Regeneration After Myocardial Infarction
Authors: Sridharan Divya , Alvi Syed Baseeruddin , Mergaye Muhamad , Ahmed Uzair , Forehand Abbey , Nottke Katie , Khan Mahmood
Published: May 2024

Nearly a billion cardiomyocytes (CMs) are lost during an acute myocardial infarction (AMI) which eventually leads to heart failure. While most conventional treatments for AMI are only palliative, transplantation of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hiPSC-CMs) has been shown to improve cardiac function. However, the use of hiPSC-CMs has been limited by their poor engraftment and survival in the ischemic microenvironment post-MI. Since hiPSC-derived mesenchymal stem cells (hiPSC-MSCs) have been shown to promote cardioprotection via paracrine mechanisms, we hypothesized that co-transplantation of hiPSC-CMs and hiPSC-MSCs in ischemic hearts may improve cardioprotection and engraftment of transplanted hiPSC-CMs. We co-cultured hiPSC-CMs and hiPSC-MSCs and assessed the changes in morphology (TEM, ICC), gene expression (qRT-PCR), and cardiac function (MEA, and calcium transients) under normoxia and hypoxia (1% O2). We observed increased maturation (elevated β-MHC expression, higher amplitude of contraction, increased sarcomere alignment) in hiPSC-CMs cultured in hiPSC-MSC derived conditioned medium. On the other hand, we observed enhanced survival (TUNEL assay) of hiPSC-CMs co-cultured with hiPSC-CMs following hypoxic insult. Additionally, following intramyocardial transplantation of (a) hiPSC-CMs, (b) hiPSC-MSCs or (c) hiPSC-CMs + hiPSC-MSCs (3:1) in a mouse MI model, we observed improved cardiac function, LVEF (p < 0.01) and FS (p<0.01) in all three groups as compared to MI-only group. We also observed effcient hiPSC-CM engraftment (human-specific markers, cTnT and HNA) in both hiPSC-CM-only and hiPSC-CM + hiPSC-MSC groups at 4-weeks post-MI. Furthermore, we observed increased angiogenesis (α-SMA, CD31) in the hiPSC-MSC-only and hiPSC-CM + hiPSC-MSC groups, as compared to control and hiPSC-CM-only groups. Taken together, our results showed that co-transplantation of hiPSC-MSCs and hiPSC-CMs can be explored as a novel combinatorial therapy for myocardial regeneration post-MI.

Funding: AHA postdoctoral fellowship to DS (916599), and NIH RO1 HLHL136232 and OSU Start-up funds to MK.

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.
Critical Environmental Limits for Middle-Aged Adults (PSU HEAT Project)
Authors: Fisher Kat , Cottle Rachel , Wolf S. Tony , Kenney W. Larry
Published: May 2024

Critical environmental limits are the combinations of temperature and humidity above which heat balance cannot be maintained for a given metabolic heat production. Our lab has previously established critical environmental limits for young and older adults; however, these limits have yet to be established for middle-aged adults. The purpose of the present study was to (1) identify critical environmental limits for middle-aged adults, and (2) investigate age-related differences in critical environmental limits at a low metabolic rate reflecting activities of daily living across the adult age spectrum. Twenty-six older (71±5 yrs, 14F/12M), 36 middle aged (51±9 yrs, 26F/10M), and 27 young adults (23±3 yrs, 13F/14M) were exposed to progressive heat stress in a controlled environmental chamber during minimal activity. Progressive heat stress for the determination of critical environmental limits comprised either (1) constant dry-bulb (Tdb) temperature at 34°C with progressively increasing water vapor pressure (Pa) by 1 mmHg every 5 minutes (Pcrit trial), or (2) constant Pa at 12 mmHg with progressively increasing Tdb by 1°C every 5 minutes (Tcrit trial). Critical environmental limits in hot-dry environments were higher in young compared to middle aged (49.3±2.3 °C vs. 45.4±4.0 °C; p = 0.002) and older adults (49.3±2.3°C vs. 43.2±4.0°C; p < 0.001), but were not different between middle aged and older adults (45.4±4.0 °C vs. 43.2±4.0°C; p = 0.125). Critical environmental limits in warm-humid conditions were lower in older adults compared to young (23.1±6.1 mmHg vs 31.7±1.5 mmHg, p < 0.001) and middle aged (23.1±6.1 mmHg vs 29.0±5.1 mmHg, p = 0.004), but were not different between the young and middle aged (31.7±1.5 mmHg vs 29.0±5.1 mmHg, p = 0.220). Age was correlated with critical environmental limits in Tcrit (R2 = 0.34; p < 0.001) and Pcrit (R2 = 0.51; p < 0.001) trials based on linear and curvilinear regression, respectively. Critical environmental limits for middle aged adults performing minimal activity in warm-humid and hot-dry environments are intermediate to young and older adults. These data demonstrate an age-related decline in critical environmental limits that can be characterized by linear decline in hot-dry environments and by curvilinear decline in warm-humid environments.

Supported by NIH Grant R01 AG067471.

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.
Antihypertensive effect of chicken blood peptide hydrolysate in streptozotocin-induced diabetic rats
Authors: Srisawat Rungrudee , Thaeomor Atcharaporn
Published: May 2024

Chicken blood peptide hydrolysate (CBH) has been reported to exert antioxidant, angiotensin 1-converting enzyme (ACE) inhibitory, and cholesterol-lowering activities. Antihypertensive effect of the CBPH was also demonstrated in spontaneously hypertensive rats. This study aimed to assess the anti-diabetic and antihypertensive effect of the CBH in streptozotocin (STZ)-induced diabetic rats. CBH was prepared from fresh chicken blood collected from an industrial slaughterhouse in Nakhon Ratchasima, Thailand. Adult male Wistar rats were randomly divided into 2 main groups: normal and STZ-induced diabetes mellitus (DM) groups. Five subgroups of each main group were given distilled water, metformin (200 mg/kg), and CBH (300, 600, 1200 mg/kg) by oral gavage for 28 days (n=10 per each group). Fasting blood sugar level and OGTT were evaluated before and at the end of experiment. Each rat underwent monitoring of blood pressure using femoral artery. STZ-induced diabetic rats showed higher fasting blood glucose concentration and area under curve from OGTT than normal rats, which was not reduced by all treatments. STZ-induced diabetic rats showed higher mean arterial blood pressure than normal rats, which was significantly reduced by metformin and CBH (300 and 1200 mg/kg) (p<0.05). The blood pressure-lowering effect of CBH suggested the potential for the application of CBH in the management of diabetic hypertension. However, attention must be paid to concerns about bird flu in certain places and prohibition of the use of blood product.

This work was supported by Suranaree University of Technology (SUT), Thailand Science Research and Innovation (TSRI), and National Science Research and Innovation Fund (NSRF) (FF1-111-65-12-30(08)).

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.