bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of 32 d of spaceflight on tendon collagen fibril morphology and nanomechanics
Authors: Bojorge Guillermo , Ortiz-Delatorre Julissa , Bialy Patrick , Ichimura Andrew , Lorenz Kent , Scott Ryan , Bagley James R. 
Published: May 2024

INTRODUCTION: Collagen is an essential component of connective tissue and plays a crucial role in elasticity, stability, and force distribution. While the adaptations of tendon to internal stimuli have been extensively researched, the impact of environmental factors (such as microgravity) on its structure and function at the nanoscopic scale (i.e., fibril level) remains largely unexplored. The purpose of this study was to determine the effects of 32 days (d) aboard the International Space Station (ISS) on murine tendon collagen fibril morphology and nanomechanics (Young’s Modulus, YM). We hypothesized there would be a decrease in fibril size and YM after spaceflight. Methods: Quadriceps tendon samples from female C57BL/6J mice from NASA Rodent Research-1 underwent chemical processing and mechanical isolation. Subsequently, collagen fibrils (n=56) were studied via atomic force microscopy (AFM; JPK NanoWizard 4a) to compare the morphology (diameter, height) and nanomechanics (average YM) between spaceflight (SF) and ground control (GC) specimens. The qp-BioAC-CB1 cantilever (spring constant: 0.3 N/m, tip radius: 10μm) was used under quantitative imaging mode (QI) for all force and morphological measurements. The data from 56 micrographs (SF n=30; GC n=26) was processed via the JPK Data Processing Software (Version 6.4.5.), and finally analyzed with Gwyddion (Version 2.62). A 2-way MANOVA compared all measurements. Results: More ‘small fibrils’ (height <50nm) were identified in the SF vs GC samples. SF fibrils averaged 20.3% smaller (width) compared to GC, but this difference was not significant (p>0.05). Additionally, while there was a trend for a lower YM in the SF samples, YM for SF specimens was not statistically different between groups (GC=3.26±1.94 MPa; SF= 2.76±1.44 MPa) (p>0.05). CONCLUSION: To our knowledge, this is the first investigation to use AFM QI-mode on tendon collagen fibrils after spaceflight. While there were no statistically significant changes in mean fibril size and YM between SF and GC, these results suggest that collagen fibrils may require more time to adapt to changes in their environment, and/or more rapid changes may take place at different levels of the collagen hierarchy. Our data provides valuable insight into mammalian tissue adaptations during spaceflight. Future research should continue these investigations with longer-duration missions to build a time-course of tendon adaptations to microgravity. FUNDING: CSUBIOTECH New Investigator Grant (JRB). 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.
PTSD-like mice display negative cardiac characteristics post-inescapable foot shock
Authors: Corker Alexa , Troncoso Miguel , Learmonth Maya , Broughton Philip , Sidles Sara , Kelly Ryan , LaRue Amanda 
Published: May 2024

Post-traumatic stress disorder (PTSD) is a risk factor for cardiovascular disease, however the mechanism behind this correlation is unknown. We hypothesized that PTSD alters cardiac homeostasis by increasing macrophage numbers and initiating cardiac fibrosis. To induce experimental PTSD, male and female C57BL/6 mice (4-weeks: n=16-17/sex, males=4.7±0.4 months old; females=4.8±0.3 months old; 8-weeks: n=13-16/sex, males=6.0±0.3 months old; females=6.3±0.5 months old) were exposed to 5 separate foot-shock incidences (IFS; 1.0 mA, 1 sec duration) in 6 min. Control mice (n=8-9/sex) were placed in the same chambers but experienced no foot shocks. Behavioral tests (16 parameters based on the DSM-5 clinical standards) were performed to characterize mice that do not demonstrate PTSD-like behavioral characteristics (NR) and PTSD-like mice. Doppler echocardiography measurements were collected serially up to 8-weeks post-IFS. Histological and gene assessments were collected 4- and 8-weeks post-IFS to measure markers of adverse cardiac remodeling that resulted in later functional changes. Over time PTSD-like mice demonstrated a decline in cardiac function becoming significantly impaired by 8-weeks as shown by an increase in E/e’ ratio along with left atrial diameter compared to controls, indicative of impaired LV filling pressure and diastolic dysfunction (p<0.05 for all). Beginning at 4-weeks post-IFS, PTSD-like mice had increased picrosirius red staining (PSR) compared to control mice (p<0.05) that remained elevated at 8-weeks. PTSD-like mice had increased macrophage numbers (Mac3) at 4-weeks post-IFS compared to control mice (p<0.05) and showed an increased trend when compared to controls 8-weeks post-IFS (p=0.09). To determine potential signaling mechanisms, Ccl2, Ccl5, and discoidin domain receptor tyrosine kinase 2 (DDR2) mRNA levels were assessed. Gene expression of Ccl2 demonstrated a decreased trend in PTSD-like mice (p=0.13), while Ccl5 (p=0.08) and DDR2 (p=0.06) mRNA demonstrated an increased trend in PTSD-like mice when compared to controls. Our data indicates that in a mouse model of PTSD, animals that demonstrate PTSD-like behaviors show signs of increased cardiac inflammation stimulating cardiac remodeling and cardiac dysfunction. This work was supported by the National Institutes of Health T32GM123055; the American Heart Association Innovator Project IPA35260039, GM113278; the Biomedical Laboratory Research and Development Service of the Veterans Affairs Offce of Research and Development Award IK2BX003922, I01BX00584; and South Carolina Translational Research Center UL1TR001450. 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.
Ineffective matching of oxygen supply to myocardial metabolism in primiparous compared to nulliparous swine
Authors: Tucker Selina , Essajee Salmon , Warne Cooper , Heard Michael , Dick Gregory , Goulopoulou Styliani , Tune Johnathan 
Published: May 2024

Maternal mortality rates in the United States are higher than any other developed country in the world. Most postpartum maternal deaths are directly related to adverse cardiovascular events and often occur in mothers who have had a healthy pregnancy. Although pregnancy is recognized as a cardiovascular stress test for the pregnant patient, understanding of how the longitudinal and dynamic cardiovascular adaptations during pregnancy contribute to augmented risk of cardiovascular complications through the postpartum period remains poorly understood. We propose that pregnancy-induced adaptations in the coronary circulation contribute to adverse cardiovascular outcomes, especially during the puerperium period (1-60 days following delivery). Accordingly, this study tested the hypothesis that the balance between coronary blood flow and myocardial metabolism is compromised in the puerperium heart. Experiments were performed in anesthetized, open-chest control nulliparous (control) and primiparous (postpartum) swine during the puerperium period (35-45 days post-delivery). Systemic and coronary hemodynamic responses were assessed under baseline conditions and in response to continuous intravenous infusion of dobutamine (1 – 30 μg/kg/min). Under baseline conditions, blood pressure averaged 107 ± 6 mmHg in both control and postpartum swine and was unaffected by dobutamine administration (P = 0.94). Heart rate increased from 77 ± 6 to 165 ± 9 beats/min in response to dobutamine in control swine vs. 52 ± 3 to 139 ± 13 beats/min in postpartum swine (P = 0.53). Coronary blood flow and myocardial oxygen delivery were significantly diminished by ~60 ± 8% at rest in postpartum swine, which is consistent with reduced myocardial oxygen consumption (MVO2). The relationship between coronary blood flow and heart rate (P < 0.0001) or MVO2 (P = 0.0002) showed a marked parallel downward shift in postpartum swine at rest and in response to dobutamine infusion. This reduction in myocardial perfusion was associated with significant reductions in myocardial lactate uptake at rest in postpartum vs. control (0.34 μmol/min/g vs. 0.08 μmol/min/g, P = 0.02). Dobutamine increased myocardial lactate uptake in control by ~47 ± 3% with little change in the postpartum group. Together, these results suggest an ineffective matching of myocardial oxygen supply to metabolism in postpartum swine. This imbalance is consistent with increased incidence of myocardial ischemia and cardiac deaths in postpartum puerperium period. This work was supported by AHA.23PRE101281, NIH R01 HL158723. 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.
High Potassium Suppresses Glycosuria and Gluconeogenesis in Tubule-specific mTORC2 Knockout Mice
Authors: Demko John , Saha Bidisha , Takagi Enzo , Weber Robert , Pearce David 
Published: May 2024

Background: Insulin promotes renal proximal tubule glucose reabsorption and suppresses gluconeogenesis (GNG). The kinase mTORC2 is critical for insulin signaling in multiple cell types. In the kidney tubules, mTORC2 knockout has recently been shown to cause glycosuria via reduced plasma membrane SGLT2 and SGLT1 as well as inappropriately increased renal GNG. Potassium (K+) also plays an important role in systemic glucose homeostasis. However, the overall importance of K+ for the regulation of renal glucose reabsorption and GNG is poorly understood. Methods: Rictor, an essential component of mTORC2, was knocked out using the Pax8-LC1 system to generate inducible tubule specific Rictor knockout (TRKO) mice. To examine the role of dietary K+ on renal glucose homeostasis, TRKO mice and wild-type (WT) littermates were fed with either a normal 0.5% K+ diet or high 3% K+ diet while in balance cages. Kidney tissue was harvested after feeding and processed to study plasma membrane glucose transporters, gluconeogenic enzymes, and mTORC2-regulated targets by western blot and qPCR. Results: On a normal K+ diet, TRKO mice had marked glycosuria despite indistinguishable blood glucose relative to WT controls. Kidney plasma membrane fractions showed decreased SGLT2 and SGLT1, supporting reduced renal glucose reabsorption. Additional metabolic testing provided evidence for renal insulin resistance with elevated fasting insulin, impaired pyruvate tolerance, elevated hemoglobin A1c, and increased renal gluconeogenic enzymes. On a high K+ diet, glycosuria resolved and plasma membrane SGLT2 and SGLT1 were restored in TRKO mice. In addition, TRKO animals fed with a high K+ diet had suppressed gluconeogenic enzymes compared to WT mice. Regardless of dietary K+ content, TRKO animals had similar reductions in phosphorylation of mTORC2 substrates compared to WT controls. Conclusion: Renal tubule mTORC2 is critical for coordinated glucose reabsorption by SGLT2 and SGLT1 as well as suppression of renal GNG. High dietary K+ promotes sodium-glucose cotransport by restoring plasma membrane SGLT2 and SGLT1 in TRKO mice. High dietary K+ also prevents excessive GNG in TRKO mice. High K+ appears to regulate these processes independently of mTORC2 and its downstream substrates, such as Akt. High K+ could potentially provide an alternative signaling mechanism to regulate renal glucose reabsorption and GNG in states of insulin resistance. Grants from the NIH (T32, R01) and The James Hilton Manning and Emma Austin Manning Foundation. 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.
Fibulin-5 Is Required for Small Artery Development and Function
Authors: Halabi Carmen , Lin Michelle , Roth Robyn , Yanagisawa Hiromi 
Published: May 2024

Introduction: Fibulins are a family of eight extracellular matrix proteins with diverse functions. Fibulin-4 and -5 (FBLN-4 and -5), in particular, have been shown to be important for elastic fiber assembly. Mutations in each of the genes lead to cutis laxa, a syndrome characterized by loose skin with variable organ involvement, particularly in the vasculature, lungs and skeleton. We recently characterized a mouse model carrying a disease-causing mutation in Fbln4 (E57K) and, contrary to conduit arteries that had elastic fiber fragmentation and stiffness, Fbln4E57K resistance arteries were structurally intact. Functionally however, Fbln4E57K mesenteric arteries exhibited endothelial dysfunction secondary to increased shear stress from large artery stiffness. Loss of FBLN5 has been shown to lead to elastic fiber fragmentation in conduit arteries, but the consequences of its loss on resistance arteries are unknown. Therefore, the objectives of this study were to determine the structural and functional consequences of FBLN5 loss on resistance arteries. Methods: We utilized adult Fbln5 knock-out (KO) mice and examined the ultrastructure of renal and mesenteric arteries via transmission electron microscopy. Functionally, using pressure myography, we characterized the myogenic tone and reactivity of Fbln5 KO and littermate control third-order mesenteric arteries to various vasoactive substances including acetylcholine, papaverine, angiotensin II, phenylephrine and potassium chloride. Results: While the internal elastic lamina (IEL) of Fbln5KO mice resistance arteries was largely intact, the external elastic lamina (EEL) was nearly absent. Similar to Fbln4E57K mice, Fbln5KO mesenteric arteries exhibited impaired endothelial-dependent vasorelaxation, likely secondary to proximal large artery stiffness. Unlike Fbln4E57K mesenteric arteries however, Fbln5 KO mesenteric arteries exhibited increased myogenic tone as well as a hypercontractile response to angiotensin II and potassium chloride, but not to phenylephrine. Conclusions: In addition to highlighting differences in the requirements for elastic fiber assembly along the arterial tree, these data emphasize the differential contribution of FBLN4 and FBLN5 to IEL vs. EEL in resistance arteries and suggest pathway-specific changes in smooth muscle cell contractility secondary to FBLN5 deficiency. This work was supported by the Washington University Pediatric Nephrology Research Core Pilot Grant Program to CMH. Funds were also provided by The Department of Pediatrics at Washington University in St. Louis School of Medicine to CMH. 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.
Cardiac Remodeling in Aged Rats after Early-life Chronic Stress: Sex-specific Outcomes and Associations with Metabolic Parameters
Authors: Sanford Ella , Dearing Carley , Olmstead Nicolette , Morano Rachel , Wulsin Lawson , Myers Brent 
Published: May 2024

Cardiovascular disease is the leading cause of death worldwide. Additionally, the incidence of cardiovascular disease varies both across the lifespan and between sexes. While multiple factors influence the development and progression of cardiovascular pathology, prolonged stress is a prominent risk factor for adverse cardiac events. However, the interactions between stress, sex, and aging that impact cardiac susceptibility remain to be determined. To this end, we examined hypertrophy of the aged myocardium in a sex- and stress-specific manner. We hypothesized that sex and stress history would interact to predict cardiac outcomes and that susceptibility/resilience would associate with behavioral, endocrine, and metabolic parameters assessed across the lifespan. In this study, rats were either exposed to chronic variable stress (CVS) in late adolescence (n = 36/sex) or remained as unstressed controls (n = 24/sex). Rats were subsequently challenged with a forced swim test (FST) and glucose tolerance test (GTT) before ageing to 15 months. The FST and GTT were then repeated prior to tissue collection. Cardiac tissue was processed for histological analysis and quantification of ventricular morphology. The data indicated that early-life chronic stress had sex-specific consequences on the aged left ventricle as CVS females had greater concentric hypertrophy. Based on the level of inward remodeling, rats were then classified as susceptible or resilient. Multiple behavioral and endocrine factors in young and aged animals significantly interacted with hypertrophy, including coping behaviors and glucocorticoid responses to hyperglycemia. However, correlations with hypertrophy were only present in males. Male rats that were not exposed to CVS had a positive association between baseline corticosterone and hypertrophy. Alternatively, CVS males had a positive correlation between visceral adiposity and hypertrophy. Thus, sex-specific cardiac susceptibility/resilience relates to endocrine and metabolic measures depending on stress history. This outcome suggests that adverse experiences can have lasting impacts on homeostatic adaptation. Ultimately, these results highlight the importance of sex and prior stress exposure for disparities in cardiovascular risk. NIH R01 HL 150559 (B Myers) NIHH F30 OD032120 (C Dearing) Pilot Translation Research Program grant from the University of Cincinnati (B Myers). 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.
Gut microbiome alterations in Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS) suggests variation in the gut-brain axis and gut metabolic potential
Authors: Schiro Gabriele , Shaik Shabana , Laubitz Daniel , Daines Michael , Rice Sydney , Ghishan Fayez , Kiela Pawel 
Published: May 2024

PANDAS, or Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections is a form of Children’s Post infectious Autoimmune Encephalopathy (CPAE), a neuropsychiatric condition characterized by the abrupt onset of diverse neuropsychiatric manifestations following streptococcal infection. It is an increasingly recognized neuropsychiatric disorder that affects a subset of children whose underlying etiology remains unclear. Gut microbiome plays a crucial role in its host brain development and is implicated throughout the life in neurobehavior and neurological disorders. Emerging evidence suggest gut dysbiosis resulting in altered intestinal flora can impair gut barrier and increase leakiness in the blood-brain barrier leading to inflammation. We aimed to investigate if the microbiome is altered in pediatric patients with PANDAS. Stool (n=19), oral (n=20) and nasal swabs (n=18) were collected from patients diagnosed with PANDAS or healthy controls (HC) and used for 16S analysis. 13 stool samples (7 HC and 6 PANDAS) samples were further used for shogun metagenomics and 17 for untargeted metabolomics (8 HC and 9 PANDAS). 16S rRNA gene sequencing identified significant difference in microbial α diversity, with lower Shannon H’ in PANDAS compared to HC (Welch’s t-test t(16.95)=-2.6, p=0.02), and in β-diversity (PERMANOVA R2=0.08 p=0.04) between PANDAS and HC fecal but not throat and nasal samples. Shotgun metagenomics identified a significant reduction in gene diversity (Welch’s t-test t(9.9)=-3.06, p=0.01) and changes in various KEGG ortholog modules involved in gut metabolism and gut-brain axis. Significant differences were also detected in metabolite composition (PERMANOVA R2=0.10, p=0.02). We also identified a set of microbial groups and metabolites enriched or depleted in CPAE patients, involved in different aspects of host physiology and gut metabolism. Our results show that PANDAS patients have an altered gut microbial community, which may exacerbate their behavioral symptoms and it should be taken into consideration in unveiling the complex pathogenesis and selection of treatment options. Arizona Department of Health Services RFGA2022-010-23 (PK) and ADHS17-00007403 (SR, MD); The Alex Manfull Fund (PK). 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.
Conditional Knockout of Glycosaminoglycan Synthesis in Bladder Epithelium Has No Effect on Urinary Voiding in Mice
Authors: Hill Warren , de Oliveira Mariana , Zeidel Mark , MacIver Bryce 
Published: May 2024

Glycosaminoglycans (GAGs) on the luminal surface of the bladder epithelium have been suggested to play an important role in barrier function and in protection from infection. There is also a substantial literature that posits a breakdown in the GAG layer may underlie, or be associated with the development of painful bladder syndrome (PBS, aka interstitial cystitis) and indeed, GAG mimetics such as pentosan polysulphate provide symptomatic relief for some patients. However, opinions on the presence and role of GAGs vary, and incontrovertible evidence is lacking. We have taken a unique approach to answering this question by engineering a highly cell-specific genetic mouse model that lacks the obligatory initiating enzyme for GAG synthesis in urothelium. Uroplakin 2-Cre (UP2-Cre) mice were crossed with xylosyltransferase 2-floxed mice to knockout the xylt2 gene in urothelium. RT-PCR confirmed the tissue specificity of the knockout in urothelium but not in bladder smooth muscle. Further, lacZ reporter staining in cryosections demonstrated highly specific expression of the Cre construct in urothelium. Mammals express two xylosyltransferases, XylT1 and XylT2 in different proportions in different tissues. While functionally similar they appear to differ in their substrate specificity and kinetics. qPCR in dissected urothelium demonstrated that XylT2 was the dominant isoform, being expressed at approximately 80-fold higher level than XylT1. Void spot assays (VSA) on filter paper (4 hours) have proven to be a reliable indicator of voiding dysfunction in mice. We conducted VSAs on female Up2 cre/xylt2 fl/fl (n=12) and xylt2 fl/fl (n=11) littermate controls aged 8 – 16 weeks. There was no significant difference in void volumes, number of primary voids, volume/void or number of microvoids (<20 μl) between controls and knockouts, whereas transurethral instillation of protamine sulfate, which injures the apical cell layer, induced pain and a significantly greater number of microvoids, with reduced primary void volumes. We conclude preliminarily, that loss of GAGs in urothelium does not affect bladder function, suggesting that GAGs do not play a role in protecting the suburothelium and adjacent sensory afferents from noxious urine components. Future work will characterize and quantitate the distribution of GAGs within the urothelium to determine whether GAGs are deployed on the luminal surface and, whether they play a role in urothelial repair from injury. NIH grant P20DK097818. 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.