bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diastolic overstretch causes inner mitochondrial collapsing and impaired force generation in isolated rat papillary muscle
Authors: Minamisawa Susumu , Nishioka Naritomo , Usui Fumio , Kusakari Yoichiro 
Published: June 2021

ObjectivesVentricular volume overload is a cause of heart failure. However, the effect of volume overload on inner‐cellular organelles are incompletely understood. We investigated the functional and morphological changes in cardiac papillary muscle by diastolic overstretch with isometrical contraction.Methods and ResultsWe used male SD‐rats (BW > 350 g) and dissected papillary muscle from the right ventricle. A papillary muscle preparation was mounted in a bath chamber and stretched to L max, at which active tension reached to the maximal level. We then stretched to 110% of Lmax (mild overstretched; mild‐OS) or 120% of Lmax (severe overstretched; severe‐OS), and stimulated papillary muscle (1 Hz, 36°C) for 4 hours with tension measurement. They were then compared with Lmax group (non overstretched; non‐OS). The active tension was immediately decreased after overstretch to 67.8±3.8% (n=6) of the non‐stretched condition in mild‐OS and to 17.3±4.0% (n=5) of the non‐stretched condition in severe‐OS. The active tension was gradually decreased with time in all preparations. After measurement of tension, papillary muscles were fixed with 2% glutaraldehyde by carefully keeping their overstretched position. We performed electron‐microscopic (EM) study and analyzed the changes in sarcomere length and morphological changes in organelles including myofilaments and mitochondria in non‐OS, mild‐OS, and severe‐OS. In mild‐OS, the sarcomere length was stretched to 2.41 mm which was comparable for 112% overstretch of non‐OS sarcomere length. In severe‐OS, the sarcomere length was stretched to 2.53 mm which was comparable for 118% overstretch. Nevertheless, the sarcomere structure of OS papillary muscles remained organized well. On the other hand, inner mitochondria density was lower in mild‐OS. Moreover, we found inner mitochondrial collapsing in severe‐OS. The EM study suggested that mitochondria were fragile under mechanical stress, such as diastolic overstretch, compared with muscle fibers and other organelles.ConclusionOverstretch of a rat isolated rat papillary muscle caused inner mitochondrial collapsing in a stress‐dependent manner. Those acute morphological changes in mitochondria by diastolic overstretch would be one of the mechanisms on pathogenesis of volume overloaded heart failure.Support or Funding InformationThis work was supported by grants from the Ministry of Education, Culture, Sports, Science and Technology of Japan (15K08190).
Interleukin 13 Promotes Cardiomyocyte Proliferation and Heart Regeneration In Vivo
Authors: Paddock Samantha J. , Wodsedalek Dylan , Kenarsary Aria , Flister Michael J. , O'Meara Caitlin C. 
Published: June 2021

AimsPreliminary data shows that the cytokine interleukin 13 (IL13) can promote neonatal mouse cardiomyocyte (CM) proliferation in vitro. From this, we hypothesize that IL13 and its downstream signaling pathway(s) play a role in stimulating mammalian heart cell cycle activity in vivo. We aim to test the role of endogenous, and exogenously administered, IL13 in promoting cardiomyocyte cell cycle activity and heart regeneration in vivo.Methods and ResultsTo understand if IL13 could promote CM proliferation in vivo, we collected whole hearts from C57/BL6J and IL13−/− neonatal mice. Heart halves were saved for histology and immunohistochemistry (IHC) and ventricle pieces for RNA extraction and protein lysates. To measure proliferation, we sectioned neonatal hearts for IHC and stained them with Proliferating Cell Nuclear Antigen (PCNA) or Phosphorylated Histone H3 (pH3). To ensure the proliferating cells were CM specific, we dual‐stained PCNA with Myocyte Enhancer Factor 2C (Mef2C) and pH3 with Cardiac Troponin T2 (cTnnt). We found CMs in IL13−/− mice show a decrease in PCNA when compared to BL6 wildtype CMs, indicative of decreased proliferation in the absence of IL13. When analyzed by qRT‐PCR, our IL13−/− mice also showed an increase in hypertrophic markers, specifically Brain Natriuretic peptide (nppb). Nppb is primarily expressed by the heart ventricles upon myocardial stretch and is shown to be upregulated during heart failure. Additionally, we found that by administering recombinant IL13 (rIL13) to the IL13−/− mice, we were able to rescue some of these phenotypes, namely increasing PCNA‐ and pH3‐positive CMs and decreasing nppb expression. To elucidate the downstream signaling pathways of IL13, we treated cultured neonatal rat CMs with rIL13 or no treatment. We preformed western blot and RNAsequencing on these CMs treated with rIL13 and both of these methods indicated a strong initial activation of Erk1/2 and Akt signaling pathways.ConclusionsOur data suggests that endogenous and exogenously administered IL13 can promote CM cell cycle activity. IL13−/− mice show decreased levels of CM proliferation, which was in part rescued when administered rIL13. We also found that rIL13 treatment in CMs activates Erk1/2 and Akt pathways, which have been shown to be pro‐proliferative and pro‐survival in CMs, respectively. In the future, IL13 and its corresponding signaling pathways could potentially be targeted to promote pro‐regenerative therapies in cardiac tissue.Support or Funding InformationAmerican Heart AssociationThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
LAT1 Promotes Angiogenic Responses in Human Endothelial Cells
Authors: Durante William , Liu Xiao‐ming , Peyton Kelly J. 
Published: June 2021

L‐type amino acid transporter 1 (LAT1) is a sodium‐independent high‐affinity transporter of large neutral amino acids, such as L‐leucine. LAT1 is abundantly expressed in a wide range of tumor cells but displays a more restricted pattern of expression in non‐transformed cells. We previously reported that LAT‐1 is present in vascular smooth muscle cells and that it plays a fundamental role in cell proliferation and survival. Since vascular endothelium also expresses LAT1, the present study investigated the functional activity and significance of this transporter in cultured human umbilical vein endothelial cells (ECs). We found that the transport of radiolabeled‐leucine by ECs was time‐dependent and linear for up to 5 minutes. The endothelial uptake of leucine was not dependent on sodium or pH, and was strongly inhibited by neutral, but not basic or acidic amino acids. Leucine transport was also abolished by the selective inhibitor of system L transport, 2‐amino‐2‐norbornanecarboxylic acid (BCH). Interestingly, blockade of leucine transport by BCH was associated with a striking concentration‐ and time‐dependent decrease in EC proliferation and DNA synthesis. Cell cycle analysis found that BCH arrested ECs in the G0/G1 phase of the cell cycle. Furthermore, EC migration following scrape injury was significantly attenuated by BCH. Moreover, the formation of endothelial tubes following the plating of ECs onto matrigel was markedly reduced by BCH. Finally, ex vivo treatment of mouse aortic rings with BCH diminished EC sprouting from these rings. In conclusion, this study demonstrates that ECs exhibit LAT1 activity, and that LAT1 plays an essential role in stimulating EC proliferation, migration, and tube formation. In addition, it identifies LAT1 as an attractive therapeutic target in treating angiogenesis‐dependent disease.Support or Funding InformationSupported by the NIH Grant HL‐59976.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The Impact of Acute Tetrahydrobiopterin Administration on Plasma Adropin Concentration in Patients with Systemic Sclerosis
Authors: Clifton Heather Lynn , Kwon Oh Sung , Machin Daniel R. , Layec Gwenael , Richardson Russell S. , Frech Tracy M. , Donato Anthony J. , Wray D. Walter 
Published: June 2021

BackgroundSystemic sclerosis (SSc) is an autoimmune disease characterized by inflammation, fibrosis, and profound vascular dysfunction. Adropin, a protein encoded by the Energy Homeostasis Associated gene (ENHO), has recently been shown to have direct effects on endothelial function [1], and as such, has been identified as a novel therapeutic target for treatment of vascular dysfunction. Our group has previously reported that administration of tetrahydrobiopterin (BH4) improved vascular function in SSc patients [2], ostensibly through its role as an essential endothelial nitric oxide synthase (eNOS) cofactor. However, the impact of BH4 administration on other related pathways has not been thoroughly investigated. Therefore, the aims of this study were (1) to determine if plasma adropin concentration differed between SSc patients and healthy controls, and (2) to assess the impact of acute oral BH4 administration on plasma adropin concentration in SSc patients.MethodsThirteen SSc patients (4 male, 9 female; age 60 ± 3 yrs; ht 171 ± 3 cm; wt 76 ± 4 kg) and 15 healthy controls (4 male, 11 female; age 62 ± 3 yrs; ht 163 ± 2 cm; wt 62 ± 3 kg) participated in this study. Venous blood samples were taken following a 5 hour fast. SSc patients consumed either BH4 (10 mg/kg) or placebo in randomized order 5 hours prior to arrival at the laboratory. Plasma adropin concentration was assessed by means of an enzyme‐linked immunosorbent assay kit (ELISA; Phoenix Pharmaceuticals, Inc., Burlingame, CA).ResultsPlasma adropin concentration was significantly lower in SSc patients compared to healthy, age‐matched controls (1.98 ± 0.02 vs. 2.07 ± 0.03 ng/mL, p=0.02). In SSc patients, plasma adropin concentration increased following acute BH4 administration (1.98 ± 0.02 to 2.00 ± 0.01 ng/mL, placebo vs. BH4, p=0.05), a restoration that neared values observed in the control group (p=0.06, SSc BH4 vs. control).ConclusionsSSc patients demonstrate a disease‐related reduction in plasma adropin concentration that can be increased by acute BH4 administration, rescuing adropin levels to near that of healthy controls. Together, these findings suggest that adropin may represent a novel therapeutic target in SSc, though further investigation is needed to explore the mechanisms by which BH4 may alter this pathway and subsequently impact endothelial function.Support or Funding InformationFunding: This project is funded in part by the National Institutes of Health (HL118313) and the U.S. Department of Veterans Affairs (RX001697, RX001418, E6910R).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Diabetic heart failure patients demonstrate a mitochondrial complex I dependent impairment in skeletal muscle
Authors: Garnham Jack , Boyle John , Roberts Lee D. , Peers Chris , Kearney Mark T. , Bowen T. Scott , Witte Klaus 
Published: June 2021

Heart failure (HF) is characterised by exercise intolerance and high mortality – both of which are exacerbated in patients with concomitant type 2 diabetes (DHF). However, cardiac dysfunction remains similar between HF and DHF patients, suggesting peripheral mechanisms may be playing a key role in the DHF phenotype. This study, therefore, aimed to explore whether a skeletal muscle specific myopathy may be present in patients with DHF compared to HF alone.Skeletal muscle biopsies were sampled consecutively from pectoralis major in age‐matched healthy controls (n=25), HF (n=52), and DHF patients (n=28). Mitochondrial O2 consumption and H2O2 flux (i.e., an index of mitochondrial ROS) were measured in saponin‐permeabilized fiber bundles (Oroboros, Innsbruck, AT). Fiber type (I and II) and size were further assessed using standard histology.Peak oxygen uptake was reduced in DHF compared to HF and control patients (12.7±0.4 vs. 15.9±0.5 and 17.5±1.2 mL/kg/min); P<0.05), while left ventricular ejection function was similar between DHF and HF patients (29±2 vs 29±1%; P>0.05). In contrast, skeletal muscle tissue showed significant impairments specific to DHF patients, particularly in relation to mitochondrial function: complex I respiration was impaired by 49 and 62 % compared to HF and controls (P<0.05), which was inversely correlated (R2=0.28, P<0.05) to increased complex I H2O2 flux. The respiratory control ratio (RCR) was also reduced (P<0.05) in DHF by 18 and 16% compared to HF and control patients. Citrate synthase activity, an index of mitochondrial content, was reduced in both HF groups compared to controls on average by 37%, but without any additional diabetic‐specific effects (P>0.05). Fiber structural alterations (size and type) remained unchanged between groups (P>0.05).In conclusion, these data provide novel evidence that skeletal muscle mitochondrial complex I function is worse in patients with DHF compared to HF alone. This impaired mitochondrial respiration in DHF patients was closely associated with increased mitochondrial ROS production, but without similar reductions in mitochondrial content suggesting the locus of limitation is qualitative. Collectively, therefore, these data provide preliminary evidence that a skeletal muscle myopathy contributes to the DHF phenotype.Support or Funding InformationMultidisciplinary Cardiovascular Research Centre (MCRC), Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, UKThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Glucose‐6‐Phosphate Dehydrogenase Regulate Metabolome‐Transcriptome Axis And Mitochondrial Malfunction In Diabetic Hearts: Implications In Pathogenesis Of Diabetic Cardiomyopathy And Mending Of Broken Hearts
Authors: Dhagia Vidhi , Joshi SachindraRaj , Soldatos Vasiliki , Rocic Petra , Edwards John , Gupte Sachin 
Published: June 2021

RationaleCardiovascular performance and the progression of heart failure is worse in patients with metabolic syndrome or type II diabetes mellitus (T2DM) than in non‐diabetics. We hypothesized that increased glucose‐6‐phosphate dehydrogenase (G6PD) activity in the diabetic heart alters the transcriptome and metabolome profile and impairs mitochondrial function, leading to decreased myocardial function.Methods and ResultsWe used hyperglycemic Goto‐Kakizaki (GK) rats fed a normal chow (NC) or a high fat diet (HFD) and JCR rats, a model of metabolic syndrome (MetS). Hemodynamics were evaluated through cardiac catheterization and metabolite profiling, and transcriptome analysis was used to detect molecular signatures underlying the disease condition. We found that cardiac contractility was decreased in GK‐NC and GK‐HFD rats, but left ventricular stiffness was increased only in GK‐HFD rats. In those hearts, G6PD activity was increased, and the G6PD activity correlated negatively with mitochondrial cytochrome c oxidase (COX) activity. Also increased was the expression of voltage‐dependent anion channel (VDAC), which was associated with increased cardiac cytosolic cytochrome c expression GK rats. In vitro experiments showed VDAC is regulated by miR‐31. Administration of epiandrosterone (30 mg/kg/day s.c.), a well‐known G6PD inhibitor, to JCR rats for 28 days increased fractional shortening, decreased LV stiffness, and attenuated fibrosis and neointimal growth in the coronary arteries as compared to vehicle treatment. This was accompanied by decreases in VDAC and increases in miR‐31. Metabolomic and transcriptomic analysis revealed that G6PD inhibition reversed MetS‐induced cardiac metabolic reprogramming and gene expression.ConclusionThese findings suggest that increased G6PD activity suppresses mitochondrial respiratory chain enzymes, induces maladaptive overexpression of mitochondrial proteins through miR pathways, and evokes left ventricular stiffness in diabetic rats fed a HFD. Moreover, inhibition of G6PD reverses the fibrosis, metabolic reprogramming, and gene expression changes seen in hearts from diabetic and MetS animals.Support or Funding InformationNIH RO1 HL 132574 (SAG)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Force‐frequency Relationship and Early Relaxation Kinetics Are Preserved Upon SR Blockade in Human Myocardium
Authors: Chung Jae‐Hoon , Canan Benjamin , Whitson Bryan , Kilic Ahmet , Mohler Peter , Janssen Paul 
Published: June 2021

Cardiomyocytes utilize calcium to activate their myofilaments and shorten, which at the organ level results in blood being pumped out of the heart and into the body. Sarcoplasmic reticulum (SR) is an organelle in cardiomyocytes that stores calcium ions and releases them during systole, when myofilament needs to be activated and sequesters them during diastole, when myofilament needs to be deactivated. Therefore, it is believed to play an integral role in the calcium handling of cardiomyocytes with potential implications in the force‐frequency relationship, as intracellular calcium is increased at higher heart rates. However, the SR is believed to be less important in calcium handling in larger mammals, which have sodium calcium exchangers (NCX) that can extrude calcium out of cardiomyocytes. We hypothesized that when the SR is blocked in human trabeculae, the relaxation function would not be affected and that force‐frequency relationship would be preserved. We isolated intact human right ventricular trabeculae from non‐failing and failing human hearts and measured various contractile and relaxation parameters upon SR blockade. We found that force‐frequency relationship is preserved even when the SR is blocked. We also found that early relaxation speed is not affected when the SR is blocked, probably because of NCX compensating for the lack of SR function. Moreover, we found that the contraction kinetics are slower upon SR blockade, potentially because L‐type calcium channel, which have slower calcium‐release kinetics than the SR, compensates for the lack of SR calcium releaseSupport or Funding InformationR01 HL113084 to Paul ML JanssenAHA 16PRE33410549 to Jae‐Hoon ChungThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
New RiPP family incorporates alpha‐N‐methylations into ribosomally encoded peptide natural products
Authors: Freeman Michael 
Published: June 2021

Microorganisms communicate using the molecular language of natural products. Amazingly, the vast majority of microorganisms on Earth are as‐of‐yet uncultivated or too difficult to genetically manipulate and directly study. Thus, the discovery of new natural products or description of new biocatalytic transformations occurring within NP pathways from these niche microbial sources often require heterologous expression in tractable microbes. This work describes the unexpected biosynthetic origins of a ribosomally synthesized and post‐translationally modified peptide (RiPP) produced by a basidiomycete fungus. We provide evidence, through heterologous expression, for iteratively incorporated alpha‐N‐methylations into a ribosomally encoded precursor protein. This never‐before‐seen post‐translational modification was thought for over forty years to be only accessible through nonribosomal peptide synthesis. Along with a very unusual leader peptide composition, this pathway hallmarks the designation of a new RiPP natural product family we termed borosins. We go on to show this borosin RiPP family can be easily engineered to create new alpha‐N‐methylated peptides in vivo through genetic recoding, a first for this type of tailoring reaction. This research adds to the handful of RiPPs so far discovered or described in fungi and highlights the vast metabolic potential of uncharacterized microorganisms.Support or Funding InformationUniversity of MinnesotaThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Mathematical modeling of left ventricle hypertrophy and dilatation in response to volume overload in heart failure: a coupled renal‐cardiac model
Authors: Anjum Sommer , Jajamovich Guido , Allen Richard , Sher Anna , Dockendorf Marissa , Musante Cynthia J. , Hallow K. Melissa 
Published: June 2021

It is well‐established that the heart remodels in response to changes in mechanical loads, and mathematical modeling of cardiac function and remodeling is an advanced field. However, volume regulation is a critical component in the pathogenesis, progression, and management of congestive heart failure, and few existing models account for the interaction between cardiac function and volume regulation by the kidney and neurohumoral signaling. A primary failure in cardiac function is compounded by volume retention as the heart and kidney work together to try to maintain organ perfusion. Eccentric hypertrophy occurs in response to volume overload, as increases in ventricular filling pressure elevate stress and stretch experienced in myocytes during diastole is believed to cause the series replication of sarcomeres and chamber enlargement. In this study, we utilized a coupled model of cardiac mechanics [1] and renal function, volume regulation, and the renin‐angiotensin‐aldosterone system[2]. We previously expanded the model to include mechanisms of cardiac hypertrophy and wall thickening in response to pressure overload – a self‐limiting process. We have now also incorporated a mechanism for left ventricle dilatation in response to volume overload, a progressive process. Specifically, myocyte length is modeled as a function of end‐diastolic myocyte stress, a relationship governed by a time constant. The model reflects the expected behavior of heart failure patients: reduced ejection fraction and increased left ventricle end diastolic volume, stress, and pressure. After inducing “heart failure” by reducing cardiac contractility, we used temporal pressure‐volume data from heart failure patients in the SOLVD study to ensure that the model accurately reflects the structural and hemodynamic changes characteristic of heart failure. We also used published data to establish an empirical relationship between left ventricle End Diastolic Stress and n‐Type Brain Natriuretic Peptide (NT‐pro BNP). We then validated the model by simulating and showing agreement with changes in the pressure‐volume loop in response to enalapril treatment in SOLVD, and NT‐proBNP at baseline and after treatment with valsartan in the VALHEFT[4] trial. This model improve our understanding of the hemodynamic interactions between renal and cardiac function and volume homeostasis in disease, and is a step toward in silico evaluation of new therapeutic mechanisms.Support or Funding InformationThis work was funded by collaborative grant from Pfizer Worldwide Research & Development and Merck & Co., Inc.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.