bluuebunny/crossref_metadata_2025_split huggingface dataset:
Voluntary exercise during 6 weeks induces pathological cardiovascular responses in MAS‐deficient mice (881.4)
Authors: Santos Daisy , Santos Robson , Oliveira Marilene , Mosienko Valentina , Plehm Ralph , Todiras Mihail , Qadri Fatimunnisa , Poglitsch Marko , Alenina Natasha , Bader Michael 
Published: June 2021

Physical training induces numerous physiological adaptations in the cardiovascular and skeletal muscle system related to changes in gene expression including modulation of the renin angiotensin system (RAS) components. Thus, the aim of this study was to evaluate the effect of running wheel training in knockout mice for the angiotensin‐(1‐7) receptor (MAS‐KO). For this we used C57Bl6 male mice (8‐12 weeks old) WT and MAS‐ KO divided into voluntary exercise group or sedentary control (N = 4‐8 per group). The aerobic training lasted 6 weeks and the amount of exercise was measured by the number of rotations per day. The gene expression responses of factors related to physiological and pathological adaptations and RAS components in the left ventricle, skeletal muscle and adipose tissue were evaluated by real‐time PCR (qPCR). Blood pressure (BP) was measured before and during the period of physical training using radio‐telemetry. The plasma levels of angiotensin peptides were determined by mass spectrometry. The results showed that in WT and MAS‐KO mice aerobic training promotes cardiac hypertrophy but in MAS‐KO it induced the expression of genes related to pathological conditions (ANP and BNP) and high plasmatic AngII / AngI ratio (0.204 vs. 0,126 pg/ml). The chronic aerobic exercise promoted an increase in skeletal muscle expression of FNDC5, irisin precursor, only in WT. In contrast, angiotensin‐(1‐7) receptor deficiency mice showed reduced FNDC5 expression in skeletal muscle (gastrocnemius and soleus) and no differences in inguinal adipose tissue UCP1 expression, opposite responses to that observed in WT mice. The MAS‐KO group presented slightly elevated baseline mean BP (105.5 ± 6.55 vs. 98.48 ± 7.65 mmHg for MAS‐KO and WT). A paradoxal increase in BP after 4 weeks of voluntary running was observed im Mas‐deficient group. It was concluded that voluntary exercise during 6 weeks induces pathological cardiovascular responses in MAS‐KO mice.Grant Funding Source: CAPES/PROBRAL
Oxygen cost of exercise hyperpnea is greater in women compared to men (882.3)
Authors: Dominelli Paolo , Render Jacqueline , Molgat‐Seon Yannick , Foster Glen , Romer Lee , Sheel A 
Published: June 2021

We tested the hypothesis that the O2 cost of exercise hyperpnea is greater in women compared to men. Healthy subjects (8M, 7F) first performed a maximal step cycle exercise test with esophageal and gastric balloon instrumentation followed by a hyperpnea familiarization trial on a separate day. Cardiorespiratory parameters were measured and flow‐ and pressure‐volume loops were constructed from the same breaths (~n=10) for each exercise stage. Days 3 and 4 involved exercise hyperpnea mimicking over 5 ventilatory levels while in the cycling position. Mimicking trials were repeated (n=4) for each ventilatory level. End‐tidal CO2 was controlled to a level corresponding to each exercise stage. Respiratory muscle O2 uptake (VO2rm) was linearly related to work of breathing (WOB) in men (r=0.94, P<0.001) and women (r=0.88, P<0.001). The VO2rm to VE relationship was assessed by fitting a regression accounting for viscous and resistive work. There was no difference in viscous work (P=0.45); however, the resistive component was ~13x greater in women (P<0.05). At maximal ventilation the absolute VO2rm was similar between sexes (0.39 vs. 0.42 l min‐1, P=0.52) despite men having a greater VE (108 vs. 169 l min‐1); but the VO2rm represented a greater fraction of whole‐body VO2 in women (14.6 vs. 9.8%, P<0.05). In conclusion, the O2 cost of exercise hyperpnea is greater in women owing to a greater resistive WOB.Grant Funding Source: Natural Sciences and Engineering Research Council of Canada
Development of a rat model of exercise under anesthesia capable of reproducing abnormal respiratory responses in chronic heart failure (882.5)
Authors: Nishizaki Akiko , Miyamoto Tadayoshi , Saku Keita , Ueda Shinya , Oga Yasuhiro , Kuwabara Yukimitsu , Ikeda Masataka , Kakino Takamori , Ide Tomomi , Kishi Takuya , Sunagawa Kenji 
Published: June 2021

Background: Abnormal ventilation during exercise is one of the major manifestations of chronic heart failure (CHF). However the lack of good animal models under anesthesia makes it difficult to investigate underlying mechanisms of respiratory abnormality. In this study, we developed a rat model of cardio‐respiratory exercise testing (CPX) under anesthesia.Methods: We used 16 weeks old rats with/without CHF. CHF was created by myocardial infarction. We induced muscle contraction by stimulating bilateral distal sciatic nerves (SNS) and mimicked exercise under anesthesia. We recorded breath‐by‐breath respiration with gas analysis. We ran a ramp protocol and a step protocol while recording respiratory responses.Results: In the ramp protocol, SNS increased minute ventilation (VE) more in CHF in normal rats (NRM). The increase in VE with the production of carbon dioxide (VE/VCO2 slope) was 23.0% more in CHF than in NRM (p<0.05).The increase in tidal volume with the respiratory rate was 16.5% less in CHF than in NRM reflecting the rapid and shallow breathing in CHF. In the step protocol, the time constant (TC) of oxygen uptake (VO2) was 78.7% longer in CHF than in NRM. Conclusion: These data indicated the model simulated respiratory abnormalities in CHF reasonably well. This novel CPX model will provide us an opportunity to clarify the mechanisms of exercise‐induced abnormal ventilation in CHF.
The purine nucleotide cycle: a cardioprotective pathway induced by HIF‐1α (887.4)
Authors: Wu Joe , Bond Cherie , Li Ying , Wright Gary 
Published: June 2021

Overexpression of hypoxia inducible factor 1α (HIF‐1α) confers robust ischemic cardioprotection. Previously we showed that HIF‐1α induces the ability to use fumarate as a terminal electron acceptor to sustain mitochondrial anaerobic electron transport chain (ETC) activity. The source of fumarate for ETC activity was established to be the purine nucleotide cycle (PNC). Here, we report that mRNA, protein, and activity of the rate‐limiting enzyme in the PNC, AMP deaminase, is induced by HIF‐1α. Thus, in addition to providing fumarate for anaerobic ETC activity, we hypothesized that induction of the PNC might serve as a mechanism that conserves the nucleotide pool during ischemia. The AMP that accumulates during ischemia can be metabolized by AMP deaminase to IMP, a membrane impermeable metabolite. Alternatively, AMP can be degraded to adenosine, which can diffuse into the interstitial space leading to a reduction of the cardiomyocyte's nucleotide pool. Consistent with our hypothesis, we show that HIF‐1α‐expressing hearts accumulate significantly less adenosine than wildtype hearts during ischemia. Collectively, our findings indicate that the PNC is a novel cardioprotective mechanism induced by HIF‐1α that preserves ETC activity while conserving the nucleotide pool.Grant Funding Source: Supported by NIH grant R01HL084302
Malignant hyperthermia: a runaway heat production futile cycle via the sodium channel (893.2)
Authors: Williams Charles 
Published: June 2021

MHis a runaway heat production futile cycle mediated via the sodium channel at the myoneural receptor site. Non depolarizing muscle relaxants do not trigger MH episodes. Depolarizing muscle relaxants, i.e. succinylcholine, are potent triggers of MH. Acetycholine, a natural depolarizer, is capable of triggering MH during transport stress, fighting activity, breeding activity and other stressors. Halothane apparently destabilizes the myoneural sodium channel which results in a rapid induction of MH. The heat released by this activity drives the further release of heat accelerating MH.The MHS pig has an increased action potential amplitude at the myoneural junction that lasts longer than normal. This is thought to induce hypertrophy of muscle mass, increased metabolic rate, and other effects. The increased metabolic activity in muscle causes the post mortem release of heat in muscle, accumulation of low acidity, which denatures the muscle proteins, resulting in pale, soft, exudative, pork.Inhalation anesthetics trigger MH by degree. Sevoflurane is a very weak trigger of MH and requires several hours of exposure to initiate an episode of MH. The transition from Halothane to Sevo lead to a 11 fold decrease in the incidence of MH in the Greater Kansas City Area from 1:50,000 to 1:550,000.Organon 9426, is a nondepolarizing muscle relaxant that prevents MH when MHS pigs are challenged with halothane or succinylcholine.
Expression of intersectin 1/2 is repressed by aldosterone through microRNAs in the CCD to alter ENaC‐mediated Na+ transport (893.4)
Authors: Butterworth Michael , Liu Xiaoning , Edinger Robert 
Published: June 2021

Aldosterone is a well characterized regulator of the epithelial sodium channel (ENaC), and increases transepithelial Na+ transport in the kidney CCD. Here we report on two related scaffold proteins, intersectin (Itsn) 1 and 2 that are aldosterone repressed via microRNA regulation. Itsns are involved in coordinating vesicle trafficking events and modulating several signaling pathways. In a cultured mCCD‐cl1 cell line, Itsn expression is reduced by aldosterone (50nM, from 6hrs), which in turn increases ENaC activity. Exogenous depletion of Itsn 1&amp;2 by siRNA increases ENaC activity (175±18% over control), while overexpression of Itsns reduces ENaC activity (40±6% of control, n=8). Immunolocalization of Itsn demonstrates a vesicular staining pattern consistent with a role in mediating ENaC endocytosis. To confirm this, we performed transepithelial capacitance recordings to assess changes in membrane surface area and demonstrate an increase in membrane retrieval with Itsn overexpression. Similar to its reported role in ROMK internalization we demonstrate here that Itsn is an aldosterone‐repressed protein (via microRNAs), involved in the altering of ENaC surface expression by regulating channel endocytosis. The molecular mechanism that underlies this function is currently under investigation.Grant Funding Source: Supported by DK078917
Molecular impact of a human divalent metal‐ion transporter‐1 (DMT1) mutation (G212V) found in two compound heterozygotes with microcytic anemia (893.40)
Authors: Shawki Ali , Illing Anthony , Mackenzie Bryan 
Published: June 2021

DMT1 is a H+‐coupled divalent metal‐ion transporter that is critical for intestinal iron (Fe) absorption and erythroid Fe utilization. Beaumont et al (Blood 107, 4168 [2006]) and Bardou‐Jacquet et al (Blood Cells Mol Dis 47, 243 [2011]) have described two patients compound heterozygous for mutations in DMT1 associated with hypochromic–microcytic anemia and hepatic Fe overload. The unrelated probands have in common a G212V substitution; the first proband also possesses a V114 deletion and the second, an N491S substitution. The probands’ siblings and parents each possess one mutated allele but were reportedly asymptomatic. We expressed mutant and wildtype (wt) DMT1 in Xenopus oocytes and used voltage‐clamp and radiotracer assays to examine the molecular impact of these mutations. The V114 deletion and N491S substitution abolished 55Fe2+ transport activity whereas 55Fe2+ transport mediated by G212V‐DMT1 did not differ from wtDMT1. G212V had no effect on the pH dependence of 55Fe2+ transport, presteady‐state kinetics, or apparent affinity for Fe2+ (K0.5 = 1.2 ± [SE] 0.4 µM cf. 1.5 ± 0.2 µM in wtDMT1; P = 0.55, n = 6 oocytes); however, G212V mediated much smaller Fe2+‐evoked currents than did wtDMT1. From simultaneous measurement of currents and 55Fe2+ fluxes in wtDMT1, we determined the H+/Fe2+ coupling ratio to be 17 ± 1 which greatly exceeds that expected for a tightly coupled system, i.e., most of the wtDMT1‐mediated current arises from H+ slippage. In contrast, the H+/Fe2+ coupling ratio for G212V was 1 ± 0.3. Slippage in cotransporters is normally thought of in terms of the energetic penalty; however, our observation that H+ slippage, but not Fe2+ transport, is disrupted in a mutant associated with disease raises the possibility that H+ slippage serve a physiological role.Grant Funding Source: Supported by PHS Grant DK080047
LAT1 (Slc7a5) null mice are embryonic lethal and exhibit neural tube defects (896.5)
Authors: Poncet Nadege , Shi Yun‐Bo , Taylor Peter , Storey Kate 
Published: June 2021

The System L1‐type amino acid transporter (LAT1; catalytic subunit Slc7a5) mediates transport of large neutral amino acids (LNAA) and thyroid hormone (TH). Some LNAA are required for full activation of the mTOR‐S6K pathway promoting protein synthesis and tissue growth. TH signalling is an important regulator of embryonic development.We generated transgenic mice with functional deletion of Slc7a5. Inter‐crossing Slc7a5+/‐ mice failed to produce Slc7a5‐/‐ offspring, indicating that Slc7a5‐knockout is embryonic lethal. Fifty‐nine embryos from such crosses analysed at E9.5 to 11.5dpc (days post coitus) showed normal Mendelian distribution: 25.4% Slc7a5‐/‐, 54.2% Slc7a5+/‐, 20.4% Slc7a5+/+. At 11.5dpc, Slc7a5‐/‐ embryos were dead, but earlier stages had beating hearts. Slc7a5‐/‐ embryos exhibited defects in neural development at 9.5/10.5dpc: 20% show a “flat‐top” brain phenotype similar to that seen in mTOR deficit embryos, while 80% exhibit a failure of anterior neural tube closure and a cruciform morphology in the caudal neural tube indicative of a neurulation defect.These preliminary data suggest an essential role of Slc7a5 in embryonic development. Further studies are now required to establish the exact cause of death, the relative importance of LNAA and TH transport by Slc7a5 for embryonic development and the mechanism by which such signalling regulates neurulation.Grant Funding Source: Supported by the Wellcome Trust
Fructose transporter knockdown S. aureus reveals critical role of the airway epithelium in limiting ASL sugar accumulation and bacterial growth (897.4)
Authors: Garnett James , Braun Daniela , Lindsay Jodi , Baker Emma , Baines Deborah 
Published: June 2021

Sugars promote the growth of S. aureus, a key bacterium in respiratory infections. We used an airway epithelial‐bacterial co‐culture model to examine the effect raising basolateral sugar concentration on the apical growth of S. aureus and the role of the epithelium in limiting this effect.S. aureus addition on the apical surface of H441 monolayers led to enhanced paracellular 14C‐L‐glucose flux across the epithelium. S. aureus growth was significantly increased by elevating basolateral glucose or fructose concentrations (p < 0.05, n = 5). A S. aureus strain in which the fructose specific permease (fruA) had been disrupted (NE768), exhibited significantly reduced growth in the presence of fructose compared to glucose, in both isolated culture (p < 0.001, n = 3) and in epithelial‐bacterial co‐culture (after 7h; p < 0.05, n = 5). S. aureus JE2 (parent strain) growth in co‐culture was greater in fructose than glucose, despite similar growth rates in isolated culture. This correlated with the reduced rate of epithelial fructose uptake compared to glucose (p < 0.05, n = 5) which we predict results in increased availability of fructose for apical bacterial growth. Pre‐treatment of H441 monolayers with metformin (1 mM, 18h), significantly inhibited both glucose‐ and fructose‐induced bacterial growth (p < 0.05, n = 4), which corresponded to reduced paracellular flux of sugar across metformin‐treated monolayers (p < 0.001, n = 8).These data provide new evidence that fructose and glucose diffuse across the airway epithelium and are utilised by S. aureus to support its growth and highlights the importance of the airway epithelium in restricting S. aureus growth by limiting airway surface liquid (ASL) sugar accumulation through paracellular permeability and uptake.Grant Funding Source: Supported by the Medical Research Council
Harmful effects of ‘fast foods’ on enteric neurons (903.1)
Authors: Rivera Leni , Leung Christopher , Pustovit Ruslan , Angus Peter , Furness John 
Published: June 2021

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide. Fats and compounds known as advanced glycation end products (AGEs) exacerbate liver injury. AGEs are complexes of reducing sugars and proteins formed when proteins are overheated in the presence of fats and sugars (e.g., by deep frying). AGEs are low in traditional diets, but are common when diets include so‐called fast foods. Impaired gastrointestinal function has been implicated in the development of NAFLD, but there is very little known about the effects AGEs and fats on enteric neurons in the context of NAFLD. This study aimed to assess damage to myenteric neurons within the ileum, caecum, and colon of C57bl/6 mice with NAFLD induced by high fat high cholesterol (HFHC), and HFHC baked diets (which increases AGEs content fivefold) for 20 weeks. There was a significant decrease in the number of Hu and nitric oxide synthase (NOS) immunoreactive neurons, as well as a loss of neurofilament immunoreactive fibres in the HFHC and HFHC baked groups compared to control. In addition, there was a significant increase in Hu translocation to the nucleus, granular Hu deposits in the cytoplasm, and the presence of cytoplasmic vacuoles (indices of damage) in the HFHC and HFHC baked groups compared to control. This work indicates that HFHC and HFHC baked diets result in enteric neuropathy that may underlie impaired gastrointestinal function in NAFLD.Grant Funding Source: National Health and Medical Research Council
EGF‐induced intestinal cell proliferation is dependent on loss of FOXO3 activity and increased lipid droplet density (906.1)
Authors: Chadalawada Gita , Chen Sharon , Cabe Maleen , Crawford Susan , Savkovic Suzana 
Published: June 2021

The proliferation of intestinal cells, critical for homeostasis, wound healing, and sustained tumor growth, is in part controlled by EGF. The source of cellular energy required for the high metabolic needs of proliferative intestinal cells remains unclear. Triacylglycerols are stored in lipid droplets (LDs), and these neutral lipids can be a rich source of energy for various cell functions. We investigated whether intestinal epithelial cells increased intracellular energy stores by inactivating FOXO3 and altering EGF receptor (EGFR) signaling targets. Human intestinal HT29 cells, treated with EGF (10 ng/ml) with or without pharmacological inhibitors of various EGFR pathways were assessed for LD status and proliferation. In HT29 cells, EGF stimulated proliferation is associated with increased LD density while LDs depletion significantly lowers EGFR and proliferation. Moreover, depleting LDs prevent EGF mediated FOXO3 inactivation supporting dependency of LD density on FOXO3. Inhibition of EGFR reduced increased LD density, suggesting the involvement of its downstream pathways. Indeed, inhibition of phosphoinositide 3‐kinase, mTOR, and prostaglandin E2 diminishes EGF stimulated LD density. The novel mechanism of intestinal cell proliferation mediated by EGFR dependent energy from increased LD density could serve as a new therapeutic approach for intestinal wound healing or cancer treatment.Grant Funding Source: Supported by NIH ‐CA160809
Influence of Hfe on neurobehavior in 1‐year‐old mice (907.5)
Authors: Chang JuOae , Kim Jonghan 
Published: June 2021

Influence of Hfe on neurobehavior in 1‐year‐old mice JuOae Chang, Jonghan Kim Department of Pharmaceutical Sciences, Bouve College of Health Sciences, Northeastern University, Boston, MA, USA Mutations in HFE (hemochromatosis) gene are associated with neurodegenerative diseases with age. To better understand the effect of HFE on the age‐related neurobehavioral dysfunction, we conducted a series of behavior tests using 1‐yr‐old mice. Hfe‐deficient (Hfe‐/‐) and control wild‐type (Hfe+/+) mice showed similar performances in marble‐burying, elevated plus maze and rotarod, suggesting that Hfe deficiency does not affect emotional behavior or motor function over age. In contrast, Hfe‐/‐ mice spent less time around the target hole than wild‐type mice (5 vs 12 s; p=0.048) in the Barnes maze test, representing reduced spatial memory function upon Hfe deficiency. Since memory loss is associated with disrupted iron homeostasis in the brain, we determined metal concentrations using ICP‐MS. Compared with controls, Hfe‐/‐ mice had similar levels of Fe and other metals (Zn, Cu, Mn) in the brain, despite elevated non‐heme iron levels in other tissues, such as serum (70% increase), liver (170%), and kidney (40%; p<0.05 for all; n=7‐8/group). These results indicate that Hfe deficiency alters systemic iron status and not brain iron. Taken together, loss of Hfe function attenuates spatial memory capacity without altering iron in the brain, suggesting a possible role of Hfe in the memory process by an iron‐independent manner.Grant Funding Source: R00 ES017781
The effect of iron overload on spatial memory and acetylcholine receptor expression in the hippocampus of rats (907.8)
Authors: Han Murui , Kim Jonghan 
Published: June 2021

Title: Effect of iron overload on spatial memory and acetylcholine receptor expression in the hippocampus of rats Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA Author: Murui Han, Jonghan Kim Iron plays an essential role in cognition and memory. While iron deficiency is associated with reduced memory capacity, we have previously demonstrated that iron overload improved a recognition memory performance in growing rats. We here characterized the effect of iron overload on special memory and explored molecular mechanisms involved in memory. Barnes maze test was conducted using rats fed iron overload diet (10,000 mg iron/kg diet) or control diet (50 mg/kg) for 4 weeks. Compared with controls, iron overload (IO) rats spent less time (57% decrease; p<0.001) and poked less errors (13% decrease; p=0.042) to find the target hole during the first training day (n=8/group), which indicates a better spatial memory upon iron loading. Western blotting was employed to examine memory‐related proteins in the hippocampus. IO rats up‐regulated nicotinic acetylcholine receptor alpha‐7 (nAChR; p=0.045; n=3‐4/group). Activities of superoxide dismutase (anti‐oxidant enzyme) or levels of malondialdehyde (lipid peroxidation marker) were not altered in IO rats. In addition, ICP‐MS results showed that brain metal levels (iron, zinc, manganese) were not altered in IO rats, indicating no evidence that IO promotes oxidative stress. Collectively, increasing memory performance under iron loading in growing rats could be due to up‐regulation of nAChR with brain metals unaffected. Supported by NIH R00 ES017781.Grant Funding Source: NIH R00 ES017781