bluuebunny/crossref_metadata_2025_split huggingface dataset:
Testosterone downregulates the Nrf2 system and promotes vascular dysfunction in HFD‐fed mice
Authors: Costa Rafael Menezes , Alves‐Lopes Rheure , Mestriner Fabíola , Tostes Rita 
Published: November 2023

BackgroundObesity is an important cause of morbidity and mortality worldwide. Mechanisms triggered by the endocrine system justify the increase in body fat depots in obese individuals. Testosterone, the predominant and most active androgen, is linked to the metabolism of insulin, glucose and lipids. In the cardiovascular system, testosterone increases reactive oxygen species (ROS) generation. Considering that 1) obesity leads to vascular oxidative stress, 2) testosterone is a potent ROS inducer, and 3) the nuclear factor E2–related factor 2 (Nrf2) is a redox‐sensitive transcription factor that activates the expression of many key antioxidant genes, we hypothesized that testosterone downregulates the Nrf2 antioxidant system, favoring ROS accumulation and subsequent vascular dysfunction in high fat diet (HFD)‐fed obese mice.MethodsFour weeks‐old male C57Bl/6J mice were anesthetized and submitted to orchiectomy (the efferent duct of each testicle was ligated and the testicles were removed) or sham‐operation. Mice received control (CD) or high fat diet (HFD) for 18 weeks. Vascular function was assessed in endothelium‐intact thoracic aortic rings and molecular mechanisms by which testosterone contribute to vascular dysfunction were determined.ResultsHFD reduced acetylcholine‐induced vascular relaxation in sham mice [(Relaxation %) CD Sham: 95.3 ± 2.7 vs. HFD Sham: 63.7 ± 1.7, n=6]. However, castration prevented HFD‐induced vascular dysfunction [(Relaxation %) CD Castrated: 94.1 ± 2.5 vs. HFD Castrated: 85.2 ± 2.4, n=7]. CD‐fed castrated mice treated with testosterone propionate exhibited decreased sensitivity to acetylcholine [(pD2) CD Sham: 7.4 ± 0.06 vs. CD Castrated + Testo: 6.7 ± 0.05, n=6]. In addition, the effects of castration in acetylcholine vasodilation in HFD mice were lost after testosterone treatment [(Relaxation %) HFD Castrated 85.2 ± 2.4 vs. HFD Castrated + Testo: 67.1 ± 1.3, n=6]. HFD increased vascular ROS generation, determined by lucigenin and amplex red assays, and castration prevented this increase. HFD increased Nrf2 expression in cytosolic fraction and decreased Nrf2 nuclear accumulation, which was linked to a decrease in mRNA expression of Nrf2‐regulated enzymes, such as catalase, heme oxygenase‐1, peroxiredoxin as well as decreased thioredoxin activity. These events were prevented in HFD‐fed castrated mice. The activation of the Nrf2 system by bardoxolone improved acetylcholine‐induced vascular relaxation in HFD‐fed mice [(Relaxation %) HFD Sham: 63.7 ± 1.7 vs. HFD Sham + Bardoxolone: 77.2 ± 1.8, n=6]. Bardoxolone and castration effects on acetylcholine vasodilation were similar. Bardoxolone increased nuclear accumulation of Nrf2 and decreased ROS generation in HFD‐fed Sham mice.ConclusionThese results indicate that testosterone downregulates Nrf2, favoring oxidative stress and vascular dysfunction in HFD‐fed obese mice.Support or Funding InformationCNPq, CAPES and FAPESP
Effects of Reactive Oxygen Species in Endothelial Cells Assessed by Observing Levels of JNK Activation
Authors: Latuska Katelyn , Farwell Sara Lynn , Lowe‐Krentz Linda 
Published: November 2023

Heart disease is the leading cause of death around the world, and it is therefore extremely important to understand the molecular signaling and responses that lead to the development of heart disease. It has been found through multiple studies that unlike disturbed flow, laminar flow induces protective effects on endothelial cells. Conversely, the reactive oxygen species that the endothelial cells are exposed to damages the cells. Specifically, this study is evaluating the effects of reactive oxygen species on endothelial cells while subjected to laminar flow. In these studies, bovine aortic endothelial cells were exposed to media containing reactive oxygen species for different time increments using a flow chamber to provide laminar flow. The levels of active JNK, a stress activated kinase, were measured using immunofluorescence microscopy. It was found that the levels of p‐JNK, the activated form of JNK, increased significantly when exposed to higher concentrations from zero to 12%. The levels of pJNK also increased over longer time intervals of reactive oxygen species in static media, from 5 minutes to 25 minutes. Cells that had been treated with hydrogen peroxide prior to laminar flow seemed to be too damaged to remain attached to the surface of the slide after the addition of flow. Hydrogen peroxide was then added to the flow media, which will act during the exposure to laminar flow. Published literature shows evidence that after endothelial cells become acclimated to the addition of laminar flow, these cells are then more resistant to damage. Therefore, we predict that similarly, the acclimated endothelial cells will become more resistant to damage and the effects of the hydrogen peroxide. Further testing of these complex systems is important, as a better understanding of the ways in which these factors interact will provide additional information to help in the prevention and treatment of heart disease.Support or Funding InformationThis research was supported by a Langer‐Simon undergraduate research award to KL. The LLK laboratory is supported by HL 536104.
MMP‐2 dysfunction in African Americans Endothelial Cells: Potential Biomarker of Hypertension Risk?
Authors: Cook Marc D , Aldokhayyil Maitha , Adeyemo Adelola , Fernhall Bo , Brown Michael 
Published: November 2023

BackgroundMMP‐2 is a biomarker that has been associated with systolic hypertension and arterial stiffness African Americans (AA). Endothelial cells (EC) constitutively express MMP‐2, where it mediates extracellular matrix turnover, and its dysfunction likely has some role in vascular function. In a small cohort of young AA and Caucasian (CA) men, we have data showing an inverse moderate correlation between circulating MMP‐2, carotid BP (r=−0.555), and aortic BP (r=−0.509) in AA (n=14) with no relationship in CA (n=18). In this preliminary in vitro study, we postulated a racial difference concerning MMP‐2 activity which contributes to endothelial dysfunction (EnDy) in AA.MethodsThe present preliminary work evaluated gene and protein expression and activity (via zymography) of secreted MMP‐2 in 4 AA and 4 CA primary human umbilical vein endothelial cells (HUVEC).ResultsMMP‐2 gene (>2‐fold increase, t2.8, 12: p=0.01*; Fig 1a) and protein (~2‐fold increase p=0.07; Fig 1b) expression were higher in AA. However, secreted MMP‐2 activity was significantly lower in AA EC (>2‐fold decrease t2.2, 14: p=0.04; Fig 2).ConclusionThese in vitro data highlight EnDy in AA primary EC and suggest that blunted MMP‐2 activity may contribute to endothelial‐mediated vascular dysfunction (reduced extracellular matrix maintenance) and subsequent hypertension risk in AA. Further studies are necessary, and underway, to investigate the epigenetic and post‐translational regulation of MMP‐2 and its vasoactive properties in AA EC.Support or Funding InformationDepartmental
Cholesterol loading rescues OxLDL‐induced activation of endothelial Rho/ROCK/Akt/p27kip1 cascade
Authors: Zhang Chongxu , Levitan Irena 
Published: November 2023

Oxidized modifications of LDL (oxLDL) are known to activate multiple signaling pathways that lead to impairment and disbalance of endothelial function impairment of the barrier function and including abnormal proliferation. It is generally believed that oxLDL exerts its effects on endothelial function via enhanced loading of cholesterol. Our studies, however, show that this is not the case. In contrast, we show that oxLDL and cholesterol loading have opposite effects on several key signaling events in human aortic endothelial cells (HAECs). Moreover, we show that cholesterol loading may rescue oxLDL‐induced effects on EC signaling. We also we provide comparative analysis of the effects of two major types of oxLDL, copper oxidized LDL (Cu‐oxLDL) and Lipoxygenase oxidized LDL (LPO‐oxLDL). Specifically, we show that both, Cu‐oxLDL or LPO‐oxLDL significantly increase Akt phosphorylation whereas inhibiting Akt with a specific inhibitor MK2206 blocks oxLDL‐induced increase in the proliferation of HAECs. Furthermore, blocking Rho with C3 or its downstream target ROCK with Y27632 significantly inhibits oxLDL‐induced Akt phosphorylation and cell proliferation induced by both Cu‐ and LPO‐oxLDL. In contrast, blocking Rac1 with MSC inhibitor has no effect neither on oxLDL‐induced Akt phosphorylation or cell proliferation of HAECs. Further evidence shows that oxLDL‐induced Rho/Akt pathway leads to downregulation of p27kip1, a well‐known negative regulator of cell proliferation. Most importantly, we also show that preloading cells with cholesterol prevents oxLDL‐induced activation of RhoA and oxLDL‐induced Akt phosphorylation. Furthermore, cholesterol pre‐loading also rescues oxLDL‐induced loss of p27kip1 expression. We propose that oxLDL impairs endothelial function by increasing the cellular content of oxysterols which disrupt the structure of endothelial membrane, an effect that can be repaired by an increase in cellular cholesterol.Support or Funding InformationNIH grants HL‐073965 and HL‐083298 to I.L.
Development of a Left Ventricular Diastolic Stress Test
Authors: Samuel Thomas Jake , Beaudry Rhys , Haykowsky Mark , Sarma Satyam , Bhella Paul , Park Suwon , Liew Mooi , Nelson Michael D. 
Published: November 2023

Left ventricular diastolic dysfunction is an important predictor of morbidity and mortality, and a major source of dyspnea upon exertion. Abnormal diastolic function, particularly during activities of daily living, is therefore an important contributor to reduced exercise tolerance and quality of life. Until recently, assessment of diastolic function has been limited to the resting condition, which often fails to recapitulate that which is experienced during daily activities. Accordingly, we sought to develop a simple— but effective— diastolic stress test which could easily be implemented into the clinical setting and differentiate patients with varying levels of diastolic dysfunction. For this investigation, we focused our attention on two known cardiovascular stressors: (a) isometric handgrip exercise (IHG), and (b) the cold pressor test (CPT). Both of these stressors are associated with robust and reproducible elevations in heart rate (HR) and arterial blood pressure (BP), without major changes in body and lung movement which are likely to be seen during dynamic exercise. We hypothesized that augmentation of the sympathetic nervous system and its associated cardiovascular response, would serve as a powerful diastolic discriminant. To test this hypothesis, we recruited six young, healthy women (age: 23 ± 4, BMI: 23.0 ± 2.8) and five elderly women without overt heart disease (age: 74 ± 7; BMI: 27.5 ± 3.0; two with Hypertension and one with Hypercholesterolemia). Heart rate, BP, Doppler mitral inflow velocities and annular tissue velocities were assessed at rest, following two minutes of IHG at 40% of maximum voluntary contraction, and following two minutes of a CPT. The major novel findings were two‐fold: First, IHG caused an increase in HR (ΔHR: 26 vs. 20bpm, young vs. old), and systolic BP (ΔSBP: 32 vs. 21mmHg, young vs. old), while the E/E′ ratio (a surrogate measure of left ventricular filling pressure) rose in the elderly population, with very little change in the young subjects (ΔE/E′: 0.87 vs. 1.80, young vs. old). Second, the CPT also increased HR (ΔHR: 6 vs. 10bpm, young vs. old) and systolic BP (ΔSBP: 17 vs. 42mmHg, young vs. old), while similarly differentiating the diastolic response in young vs. older participants (ΔE/E′: −0.07 vs. 1.47, young vs. old). Taken together, these preliminary data demonstrate both feasibility and efficacy of this novel diastolic stress test. More work is needed to apply this work to individuals at risk for or with heart failure and compare this approach to existing stress modalities.Support or Funding InformationThis work was supported by AHA 16SDG27260115 and the Harry S. Moss Heart Trust.
Tsg101 Regulates Rab11FIP3‐Mediated Endosomal Recycling of IGF‐1R in Physiological Cardiac Hypertrophy
Authors: Essandoh Kobina , Wang Xiaohong , Jiang Min , Mu Xingjiang , Peng Jiangtong , Li Yutian , Deng Shan , Salem Esam , Rubinstein Jack , Fan Guochang 
Published: November 2023

BackgroundDevelopment of physiological cardiac hypertrophy has primarily been ascribed to the insulin‐like growth factor 1 (IGF‐1) and its receptor, IGF‐1R and subsequent activation of the Akt pathway. Previous studies have demonstrated the effects of IGF‐1 on both pathological and physiological remodeling whereas IGF‐1R has consistently been linked to only physiological heart growth. Thus, the balance between de novo synthesis and recycling or degradation of IGF‐1R through the endosomal system is critical for physiological heart growth. However, regulation of endosome‐mediated recycling and degradation of IGF‐1R during physiological hypertrophy has not been investigated.Methods & ResultsIn the current study, we sought to determine the role of endosome‐mediated recycling and degradation of IGF‐1R on physiological cardiac hypertrophy. Male FVB/n mice (7–8 weeks old) underwent intense treadmill exercise training for 1 week to induce physiological hypertrophy. We observed that mediators of recycling (Rab11a, Rab11FIP3) and degradation (Rab7) of endosomes were enhanced in exercise‐trained mice. Of importance, levels of tumor susceptibility gene 101 (Tsg101), a key member of the Endosomal Sorting Complex required for Transport (ESCRT), were dramatically elevated in hearts of exercise‐trained mice, compared to controls (n=9, p<0.01). To determine the role of Tsg101 on physiological hypertrophy, we generated a transgenic mice model with cardiac‐specific overexpression of Tsg101. These transgenic mice exhibited a physiological hypertrophy‐like phenotype at 8 weeks, evidenced by the absence of cardiac fibrosis, significant improvement of cardiac function, increased total and plasma membrane levels of IGF‐1R and increased phosphorylation of Akt. Mechanistically, we identified that Tsg101 interacted with IGF‐1R and Rab11FIP3, which constitutively binds to Rab11a at endosomal recycling compartments to initiate recycling of endosomes. In vitro, adenovirus‐mediated overexpression of Tsg101 in neonatal rat cardiomyocytes resulted in increased cardiomyocyte size, which was blocked by addition of monensin, an inhibitor of Rab11/FIP3‐endosome recycling. Furthermore, cardiac‐specific knockdown of Tsg101 showed a significant reduction in levels of Rab11a, Rab11FIP3, IGF‐1R and Akt phosphorylation. Most interestingly, Tsg101‐knockdown mice failed to develop cardiac hypertrophy after intense treadmill training.ConclusionOur data identify Tsg101 as a novel regulator of physiological cardiac hypertrophy through facilitating the Rab11FIP3‐mediated endosomal recycling of IGF‐1R.Support or Funding InformationNIH 2R01HL‐087861
AICAR Treatment Does Not Prevent Increases in Exercise Capacity or Muscle Heat Shock Protein 25 with Treadmill Training in Mice
Authors: Godwin Kyle , Huey Kimberly 
Published: November 2023

Exercise and 5‐aminoimidazole‐4‐carboxamide‐1‐β‐D‐ribofuranoside (AICAR) are agonists of AMP‐activated protein kinase (AMPK) and are used in type II diabetes treatment. Treatment effectiveness may be due to AMPK activation and up‐regulation of heat shock proteins (Hsps) in skeletal muscle, including Hsp25 and αB‐crystallin. Decreased Hsp25 expression in skeletal muscle is associated with insulin resistance in rats and data in both animals and humans suggests that increased Hsp expression in skeletal muscle may contribute to the prevention and treatment of insulin resistance. However, some evidence in both animals and humans suggests the combination of exercise and AMPK‐activating drugs such as AICAR may decrease exercise‐training adaptations. These experiments tested the hypothesis that AICAR + treadmill training (TM) would attenuate increases in exercise capacity, muscle force, and Hsp expression compared to training alone. Adult, male C57 mice were divided into 4 groups (n = 8–10/group): 1‐Placebo, 2‐AICAR, 3‐Placebo + TM, and 4‐Aicar + TM. Groups received daily placebo or AICAR with or without TM over 7 days. Plantarflexor muscle force and fatigue (% of max force after 10 contractions) were measured in vivo and exercise capacity was assessed with pre‐ and post‐treadmill tests. Muscle Hsp25 and αB‐crystallin protein levels were quantified with western blot. Data was statistically analyzed with 2‐way ANOVAs and post‐hoc tests. AICAR + TM did not affect training‐associated increases in exercise capacity compared to Placebo + TM (D time pre to post: 903 ± 164 vs. 1,188 ± 99 sec. for AICAR and TM, respectively, p<0.05). Muscle force was unchanged with AICAR in either TM or sedentary groups compared to placebo (Placebo: 1.2 ± 0.07 vs. 1.3± 0.07 and AICAR: 1.4 ± 0.08 vs. 1.5 ± 0.12 g/g body mass, for sedentary and TM, respectively, p<0.05). Fatigability was greater with AICAR in sedentary mice; however, AICAR + TM decreased fatigability compared to AICAR alone (p<0.05). TM increased Hsp25 levels independent of treatment (Placebo: 0.09 ± 0.01 vs. 0.15 ± 0.01 and AICAR 0.15 ± 0.02 vs. 0.17 ±0.02 AU, for sedentary and TM, respectively, p<0.05) and AICAR increased Hsp25 in the sedentary group compared to placebo (0.15 ± 0.02 vs. 0.09 ± 0.01 AU, p<0.05). AICAR prevented the TM‐associated increase in αB‐crystallin compared to placebo (Placebo: 0.11 ± 0.02 vs. 0.17 ± 0.01 and AICAR: 0.10 ± 0.01 vs. 0.01 ± 0.02 AU, for sedentary and TM, respectively, p<0.05). These findings suggest AICAR does not impair training‐associated increases in exercise capacity or Hsp25 muscle protein or negatively impact muscle force production. Taken together, these treatments could positively impact type II diabetics who often have reduced exercise capacity and skeletal muscle Hsp25 levels.Support or Funding InformationSupported by APS UGSRF.
Skeletal Muscle Adaptations to Exercise in a Pre‐clinical Model of Myotonic Dystrophy Type 1
Authors: Manta Alexander , Stouth Derek W , Rebalka Irena A , Kalmar Jayne M , Hawke Thomas J , Ljubicic Vladimir 
Published: November 2023

Myotonic dystrophy type I (DM1) is the second most common muscular dystrophy (MD), and most prevalent adult form of MD. Caused by a CTG microsatellite repeat expansion in the 3′ untranslated region (UTR) of the DMPK gene, muscle weakness, wasting, myotonia, and insulin resistance most prominently characterize DM1. Recent studies investigating the therapeutic efficacy of exercise training in DM1 patients demonstrate that chronic physical activity can elicit some functional benefits. Enhancing our understanding of exercise‐induced alterations in DM1 biology may assist in the discovery of effective lifestyle and/or pharmacological interventions to mitigate DM1. Thus, the purpose of this investigation was to examine exercise‐induced skeletal muscle plasticity in a pre‐clinical model of DM1. Three groups of mice (3–6 months old, n = 10–14/group) were utilized: i) sedentary human skeletal actin‐long repeat (HSA‐LR) mice (SED‐DM1), ii) HSA‐LR mice with volitional access to a home cage running wheel for 6–8 weeks (EX‐DM1), and iii) sedentary wild‐type mice (WT). HSA‐LR animals are engineered to possess a CTG expansion of ~250 repeats in the 3′ UTR of the HSA gene. These mice best recapitulate the myopathy characteristic of the human disorder, and thus serve as the most heavily employed pre‐clinical model of DM1. EX‐DM1 animals ran 5.6 km/day, which is similar to the running volume of healthy, WT mice previously reported in the literature. Utilizing the pen test to examine muscular endurance and motor performance, the WT group exhibited a significantly higher score, as compared to SED‐DM1 mice. The pen test score was normalized in the EX‐DM1 group. EX‐DM1 mice also demonstrated rescued forelimb grip strength, which was 24% lower (p < 0.05) in the SED‐DM1 animals versus the WT group. Direct, in situ stimulation of the plantar flexor muscle group revealed that chronic exercise normalized the aberrant force‐frequency relationship observed between WT and SED‐DM1 groups. Furthermore, EX‐DM1 animals demonstrated a tendency for enhanced fatigue resistance relative to WT and SED‐DM1 mice during repetitive, electrical stimulation‐evoked muscle contractile activity in situ. Finally, preliminary results suggest that chronic exercise can diminish the severity of myotonic discharges observed in the muscle of DM1 mice. Collectively, our data suggest that chronic physical activity elicits numerous favorable adaptations in DM1 biology. Examination of the underlying molecular mechanisms driving this beneficial muscle remodelling is warranted.Support or Funding InformationNatural Science and Engineering Research Council of Canada (NSERC)
PHYSIOLOGICAL, IMMUNOLOGICAL AND BIOCHEMICAL CHANGES IN ATHLETES DURING ADVENTURE RACE
Authors: Silva Romeu Paulo Martins , Silva Carolina Freitas , Bortolini Cristiane Soares Ferreira , Maggi Luiz Eduardo , Bortolini Miguel Junior Sordi , Vilaça Alexandre , Penha‐Silva Nilson 
Published: November 2023

ObjectiveTo investigate the occurrence of physiological, immunological and biochemical changes in adventure race.MethodsTwenty‐five professional athletes, 15 men (age 31.4 ± 5.36 years) and 10 women (age 27.8 ± 5.18 years) traveled 460 km for 4 days long in an international edition of Ecomotion/Pro AR World. Blood and saliva samples were collected before (day 0) and after (day 4) the competition.ResultsThere were risings of α‐amylase and cortisol levels in saliva after the race (p<0.05). The relative changing percentages of α‐amylase and cortisol were significantly higher in women than in men (p<0.05). There were less relative changing percentages of glucose and lactate levels in women than in men (p<0.05). After the competition leukocyte counts got higher compare to the beginning and among gender women got higher leukocyte counts than men (p<0.05).ConclusionLong‐lasting exercises with high intensity moments and little sleep, as adventure race, promoted an increased stress and changes in the immune system which can harm athletes' sports performance and health.Support or Funding InformationFUNDAÇÃO DE AMPARO A PESQUISA DE MINAS GERAIS (FAPEMIG)