bluuebunny/crossref_metadata_2025_split huggingface dataset:
The ER/SR Ca2+ sensing protein STIM1 is essential for normal cardiomyocyte function (1150.8)
Authors: Collins Helen , He Lan , Pat Betty , Zou Luyun , Qu Jing , Zhou Lufang , Litovsky Silvio , Yang Qinglin , Young Martin , Chatham John 
Published: June 2021

Store‐operated Ca2+ entry (SOCE) and its molecular mediator, the endoplasmic reticulum (ER) Ca2+ sensor, Stromal interaction molecule 1 (STIM1) have been implicated in hypertrophic signaling. However, since the physiological role of STIM1 in the adult heart remains unknown, we developed a cardiomyocyte‐restricted STIM1 knockout (crSTIM1‐KO) mouse. Using serial echocardiography and histological analysis, we observed a progressive decline in contractile function from 20 weeks of age, which was associated with marked left ventricular dilatation by 36 weeks. Immunoblot analyses revealed that crSTIM1‐KO hearts exhibit increased ER stress prior to contractile dysfunction (i.e., 12 weeks old) as indicated by increased levels of CHOP. Electron microscopy revealed ER dilatation, mitochondrial disorganization and smaller mitochondria in crSTIM1‐KO hearts, which was associated with a decrease in mitofusin 2 and an increase in Drp1 consistent with increased mitochondrial fission. Interestingly, perfused hearts from 20 week crSTIM1‐KO mice exhibited significant reductions in both glucose oxidation and net lactate release. These data demonstrate for the first time that STIM1 plays an essential role in normal cardiomyocyte function in the adult heart and may be mediated through regulation of ER/ mitochondrial function and/or metabolism.Grant Funding Source: Supported by NIH grants HL101192 and HL110366 and William W Featheringill Postdoctoral Fellowship
Matrix metalloproteinase 2 increases ROS in aortic tissue (1153.10)
Authors: Prado Alejandro , Pernomian Laena , Azevedo Aline , Castro Myrella , Bendhack Lusiane , Tanus‐Santos Jose , Gerlach Raquel 
Published: June 2021

So far ROS has been shown to activate MMP‐2, a key protease in cardiovascular diseases. This study tested whether MMP‐2´s effect on vascular dysfunction was mediated by ROS. The cDNA of the catalytic domain of the human MMP‐2 was cloned in fusion with GFP, and the activity of the hMMP‐2cat/GFP was assayed. The rhMMP‐2/GFP protein was catalytically active (both were expressed and purified from E coli). Both proteins were injected into the lumen of New Zealand rabbit aortas, and filled vessels (MMP‐2‐FA) were incubated for 30 min. Concentration used: 1.2 ug/ml or 16 mmol/L, 4 times the level of MMP‐2 found in healthy humans. The exogenous MMP‐2 increase in aortic wall was tracked by direct observation of GFP, immunostaining and gelatinolytic activity. This last parameter doubled in the MMP‐2‐FA, as well as in MMP‐2‐FA+PMSF (a serine‐proteinase inhibitor), but displayed normal values in MMP‐2‐FA+ Doxycycline (an MMP inhibitor). ROS activity was increased by 85% (±4%) in MMP‐2‐FA, while there was only a slight increase in the MMP‐2‐FA co‐infused with the MMP inhibitor Doxycycline (15 ±8%). Apocinin and PEG Catalase decreased the levels of ROS in MMP‐2‐FA to basal levels (P<0.001), while Tiron only reduced ROS levels by 17%(±8%)(p<0.05). This is the first study to show that MMP‐2 at levels described in plasma of patients are sufficient to increase ROS in vessels.Grant Funding Source: FAPESP
Oxidative stress increases pulmonary capillary permeability in lean Zucker rats with chronic hyperglycemia (1153.6)
Authors: Lu Silu , Xiang Lusha , Clemmer John , Mittwede Peter , Hester Robert 
Published: June 2021

Chronic hyperglycemia in obesity and diabetes is associated with increased vascular oxidative stress and endothelial dysfunction, including an increase in endothelial permeability. Increases in pulmonary capillary permeability associated with hyperglycemia and oxidative stress may contribute to lung edema in obesity and diabetes following trauma. We hypothesized that chronic hyperglycemia‐induced oxidative stress increases pulmonary capillary filtration coefficient (Kf). Lean Zucker rats (LZ) (n=12, STZ 50 mg/kg, ip) were hyperglycemia for 4 wks. A subgroup (n=6) was treated with apocynin (NADPH oxidase inhibitor, 2 mM in drinking water for 4 wks). Kf was measured in isolated lungs. Superoxide was measured in aortas using DHE. PMS (superoxide donor, 1 µM) was added to the isolated lung perfusate to determine the effect of an increased superoxide on Kf. Aortas from control LZ (LC) were treated with PMS to verify an increase in superoxide levels. STZ‐treated LZ (LS) exhibited significantly increased vascular superoxide levels and Kf (31 ± 4 ml/mmHg/g/min) compared to LC (7 ± 3 ml/mmHg/g/min). Apocynin treatment significantly reduced the superoxide levels and Kf (18 ± 3 ml/mmHg/g/min) in LS. PMS significantly increased Kf (37 ± 7 ml/mmHg/g/min) in isolated lungs from LC. These results suggest that, during chronic hyperglycemia, elevated vascular superoxide increases pulmonary permeability.Grant Funding Source: Supported by AHA‐12POST12060126, NIH HL‐51971, HL‐89581, and AHA‐12SDG12050525
Contractile function in myocytes from aged hearts is altered with glucose compared to fat as the substrate (1154.7)
Authors: Barton Gregory , Diffee Gary , Aiken Judd 
Published: June 2021

Substrate utilization generally favors fatty acid oxidation over glucose utilization in normal healthy hearts. Aging is associated with attenuated myocardial contractile function; however age related changes in substrate utilization are less understood. Most studies of metabolic aspects on cardiac function have been done in whole hearts and little information is available about cellular contractile responses in the presence of different substrates. We determined substrate effects on contractile properties in isolated myocytes from young (6 months) and old (33 months) FBN rats. We measured percent shortening and rate of shortening at time 0 (T0) and after 10 minutes (T10) of continuous stimulation at 2 Hz in myocytes isolated from healthy hearts and bathed in Ringers solution containing either 11mM glucose (G) or 0.4 mM oleate (O). Both percent shortening and rate of shortening at T10 were lower than at T0 regardless of age or substrate. However, in old myocytes there was a significantly (p < 0.05) larger decrease over time (∆ = T10 ‐ T0) when G (∆ % shortening = ‐2.87) was the substrate compared to O (∆ % shortening = ‐1.37). In young myocytes there were no substrate differences (∆ % shortening = ‐1.36 and ‐1.42 in G and O, respectively). Similar results were seen with the rate of shortening. These data suggest that aging results in altered substrate utilization that affects myocyte contractile properties.Grant Funding Source: Supported by NIH AG 030423
Skeletal muscle proteomic signature in pulmonary arterial hypertension (1158.8)
Authors: Pflieger Aude , Potus François , Malenfant Simon , Breuils‐Bonnet Sandra , Bonnet Sebastien , Provencher Steeve 
Published: June 2021

Introduction: Pulmonary arterial hypertension (PAH) is characterized by a progressive increase in pulmonary vascular resistance leading to right ventricular (RV) hypertrophy and ultimately failure. Numerous observations suggest that exercise limitation in pulmonary arterial hypertension (PAH) is not solely due to cardio‐pulmonary impairment, but that other determinants such as skeletal muscle abnormalities are involved. To better understand the exercise limitation origins in PAH, we studied the proteomic signature of skeletal muscle impairment in idiopathic PAH (iPAH) patients.Methods and results: Muscle proteins from 4 iPAH patients and 4 sex and age matched controls were extracted following quadriceps muscle biopsy. Fractioned peptides were then tagged using isobaric Tags for Relative and Absolute Quantitation (iTRAQ, ABsciex) specific for each patient. Tagged peptides were then mixed, fractioned, identified and quantified using mass spectrometry quantitative method. Over 900 proteins were identified, among them, 9 were under‐expressed and 7 were over‐expressed in all iPAH patient quadriceps. More than 75% of the under‐expressed proteins are involved in oxidative metabolism and most other highlighted proteins play a role in myogenesis. These findings were structurally associated with decreased mitochondrial density (citrate synthase assay) and impaired mitochondrial structure measured by electronic microscopy, while muscle fibers distribution was unchanged. Functionally, all these abnormalities resulted in decreases in oxidative metabolism (pyruvate dehydrogenases assay).Conclusions: For the first time in humans, we provide evidences that, as in lungs and the right ventricle, the impaired mitochondrial metabolism is also present in skeletal muscle suggesting that PAH might be considered as a global mitochondrial/metabolic disease.
HDL and lipid components of HDL inhibit oxysterol induced macrophage differentiation by altering cellular lipid status and mechanisms involving oxidative stress (1161.2)
Authors: Hayden John , Martinez Didio , Franco Daniel 
Published: June 2021

Background and Objectives: we have reported that monocytes treated with the proatherogenic oxysterol 7‐ketocholesterol (7KC) form macrophages and become foam cells in vitro. HDL has been shown to possess many antiatherogenic properties; however, its effect on modulating oxysterol‐induced differentiation has not been studied. Thus, we tested the hypothesis that HDL and components of HDL inhibit oxysterol induced macrophage formation. Methods: serum deprived THP‐1 monocytic cells were treated with 7KC for up to 7d and treated with various physiologic concentrations of HDL, recombinant HDL and phospholipids. Formation of adherent macrophages was determined, cellular ROS and glutathione status were assessed, and cell lysate were prepared for the analysis of varied lipid components by HPLC. Results: native HDL (2.5‐100 μg protein/ml), lipid components of HDL and recombinant HDL containing phosphatidylcholine (PtC) markedly inhibited (P<.001) macrophage formation. Moreover, the exogenous addition of PtC, with varying fatty acid composition, also inhibited (P<.001) macrophage formation. Upon further examination, 7KC treatment resulted in reduced concentration of cellular PtC which was associated with a increase in reactive oxygen species (ROS) and marked alteration of glutathione status (GSH:GSSG ratio ~10). In contrast to PtC, cellular levels of ceramide and sphingomyelin were increased during cellular stress by 7KC treatment. HDL treatment restored PtC and sphingomyelin levels to non‐oxysterol treated cells; and exogenous PtC supplementation, or HDL treatment, restored ROS and GSH status to levels similar to non‐treated controls. Conclusions: these results demonstrate that HDL inhibited macrophage differentiation induced by 7KC treatment. In addition, HDL possesses the capability to alter lipid status and mechanisms controlling oxidative stress that are involved, in part, with monocyte‐macrophage differentiation.Grant Funding Source: Supported by grants from the Veterans Affairs VISN18 and Carl T. Hayden Medical Research Foundation
Trans IL‐6 signaling and suppressed muscle protein synthesis with cancer (1163.11)
Authors: Puppa Melissa , Narsale Aditi , Rose‐John Stefan , Carson James 
Published: June 2021

Systemic inflammation is associated with many types of cancer‐induced cachexia, and often includes increased IL‐6 levels. Tissue STAT3 activation can occur by classical or trans IL‐6 signaling. Inhibition of IL‐6 or muscle STAT3 can attenuate cachexia muscle mass loss in tumor bearing mice. The purpose of this study was to determine if inhibition of either trans IL‐6 or systemic STAT3/NfκB signaling could improve cancer‐induced suppression of muscle protein synthesis in ApcMin/+ (Min) mice. After the initiation of cachexia Min mice were randomized to receive sgp130Fc (150ug/wk) to inhibit trans IL‐6 signaling, PDTC (10mg/kg/day) to inhibit STAT3/NfκB signaling, or PBS for 2‐wks. At 16 weeks of age Min mice had lost 7% body weight (BW). Administration of PDTC or sgp130Fc attenuated further BW loss, while PBS mice lost an additional 8% BW. Additionally, PDTC and sgp130Fc attenuated the cachexia‐mediated loss of gastrocnemius muscle mass. While sgp130Fc was unable to attenuate cachexia suppression of muscle protein synthesis, PDTC administration increased muscle protein synthesis. In summary, trans IL‐6 signaling inhibition was sufficient to attenuate cancer‐induced muscle mass loss independent of effects on suppressed muscle protein synthesis, while global STAT3 and NfκB inhibition rescued both muscle mass and protein synthesis during cancer cachexia.Grant Funding Source: Supported by R01CA121249
An investigation of kinases responsible for site‐specific phosphorylation of p70S6K1 in skeletal muscle following chronic functional overloading (1163.13)
Authors: Martin Tony , Dennis Michael , Gordon Bradley , Kimball Scot , Jefferson Leonard 
Published: June 2021

The present project was designed to investigate the phosphorylation of p70S6K1 in an animal model of induced hypertrophic growth of skeletal muscle. Within 24 h of chronic functional overloading of the plantaris muscle by unilateral tenotomy in male Sprague Dawley rats, phosphorylation of p70S6K1 on Thr389 and Thr421/Ser424 was significantly increased. Treatment of rats with inhibitors of mTOR and c‐Jun N‐terminal Kinase (JNK) provided evidence of a role for the JNK signaling pathway in mediating regulation of p70S6K1. To investigate further a role for JNK in p70S6K1 phosphorylation, a cell culture model was employed. In HEK293E cells deprived of serum, treatment with IGF1 enhanced phosphorylation of Thr389 and Thr421/Ser424 sites. Inhibition of mTORC1 and/or JNK using selective inhibitors revealed a complex interaction suggesting that mTORC1 signaling pathway mediates the IGF1‐induced phosphorylation of both Thr389 and the Thr421/Ser424 sites, whereas JNK is responsible for basal phosphorylation (i.e. phosphorylation in serum‐deprived cells). Further support for this suggestion is provided by the finding that anisomycin, a JNK activator specifically stimulated phosphorylation of Thr421/Ser424 but not Thr389. Taken together, these results demonstrate that both the mTORC1 and JNK signaling pathways contribute to the stimulation of cell growth by mediating site specific phosphorylation of p70S6K1.Grant Funding Source: Supported by NIH Grant DK15658
Docosahexaenoic acid attenuates palmitate‐induced unfolded protein response in myotubes (1163.21)
Authors: Woodworth‐Hobbs Myra , Hudson Matthew , Rahnert Jill , Zheng Bin , Price S. 
Published: June 2021

Accumulation of saturated fatty acids in skeletal muscle results in dysregulation of protein metabolism and muscle atrophy. In cultured myotubes, the saturated fatty acid palmitate (PA) stimulates protein degradation and decreases cell size, while co‐treatment with the omega‐3 polyunsaturated fatty acid docosahexaenoic acid (DHA) prevents the response. It has been shown that PA also induces endoplasmic reticulum stress and activates the unfolded protein response (UPR) in myotubes, resulting in decreased protein synthesis. The objective of this study is to test whether DHA protects against palmitate‐induced endoplasmic reticulum stress and activation of the UPR. C2C12 myotubes were treated with 500μM PA and/or 100μM DHA for 24h and protein markers of the UPR were evaluated by western analysis. PA induced activation of protein kinase R‐like protein kinase (PERK), as indicated by an increased phospho‐PERK:total PERK ratio. PA also induced phosphorylation and inactivation of eukaryotic initiation factor 2α (eIF2α). While co‐treatment with DHA attenuated the effects of PA on PERK ratio, eIF2α phosphorylation was similar in myotubes treated with PA and PA+DHA. These results indicate that DHA attenuates the effects of PA on activation of the UPR but does not restore global protein synthesis; this suggests that DHA restores myotube diameter primarily by inhibiting palmitate‐induced protein degradation.Grant Funding Source: Supported by NIH RO1DK95610, AHA GRNT7660020, and VA MERIT X01BX001456 awarded to SR Price.
Bone density is maintained during forced disuse in hibernators throughout both the active and hibernation seasons (1166.1)
Authors: Bogren Lori , Johnston Erin , Van Tets Ian , LeBlanc Adrian , Drew Kelly 
Published: June 2021

Long‐term space flight produces a decrease in bone density that poses a hazard for astronauts during and after missions in space. Bone loss is due in part to disuse since long‐term bed rest immobilization in many animals mimics the effects of space flight on bone mineral density. Decreases in metabolism associated with aging and hormones that signal energy status are also thought to contribute to a loss of skeletal mass. Hibernation is a unique metabolic state where some species of mammals remain inactive for periods of up to 8 months and metabolism decreases to 1 to 2 percent of basal metabolic rate. Hibernating ground squirrels maintain bone strength despite long periods of disuse and decreased metabolism. The present study sought to delineate changes in bone density that occur during natural disuse (torpor) and forced disuse (sciatic neurectomy) in the hind limbs of the arctic ground squirrel over the winter and summer seasons. We found that arctic ground squirrels retained bone density with both natural and forced disuse and that this persisted throughout both the summer/active and winter/hibernations season.Further research is needed to better understand the relationship between skeletal load (use), metabolism and energy homeostasis and bone density that may lead to therapeutics or strategies to maintain bone density in space.Grant Funding Source: Supported by the Alaska Space Grant Program
Activation of peripheral υ‐opioid receptors suppresses ischemic mediator‐induced cardiac excitatory reflex responses (1169.11)
Authors: Fu Liang‐Wu , Longhurst John 
Published: June 2021

Myocardial ischemia evokes cardiac sympathoexcitatory reflex responses through stimulation of cardiac spinal afferents. We have demonstrated that a P2X2/3 agonist stimulates ischemia‐sensitive, but not ischemia‐insensitive cardiac sympathetic afferents, while blockade of peripheral opioid receptors with naloxone enhances the responses of these afferents to P2 receptor activation with ATP. In the present study we tested the hypothesis that opioids, through stimulation of peripheral µ‐opioid receptors, inhibit excitatory reflex responses induced by ATP. Hemodynamic parameters were recorded in six anesthetized rats after bilateral vagotomy. Injection of the P2X2/3 receptor agonist α,β‐meATP (125‐250 nmol), into the pericardial sack increased mean blood pressure (BP) from 85±6 to 115±7 mmHg, a response that was reduced by 19% following activation of peripheral opioid µ‐receptors with intrapericardial DAMGO, a selective µ‐receptor agonist. In contrast, blockade of opioid µ‐receptors with intrapericardial CTOP, selective µ‐receptor antagonist, exaggerated the α,β‐meATP‐induced BP response by 22% in five other rats. Single‐unit cardiac afferent recordings showed that the responses of five ischemia‐sensitive cardiac spinal afferents to α,β‐meATP were enhanced by 51% after epicardial CTOP. Together, these data suggest that peripheral µ‐opioid receptor stimulation suppresses P2X2/3 receptor evoked cardiac excitatory reflex responses through inhibition of ischemia‐sensitive cardiac sympathetic afferents. (Supported by NIH Grant HL66217)Grant Funding Source: NIH
Tonic arterial chemoreceptor activity contributes to cardiac, but not renal, sympathetic activation in heart failure (1169.2)
Authors: Xing Daniel , May Clive , Ramchandra Rohit 
Published: June 2021

In heart failure (HF) cardiac sympathetic nerve activity (CSNA) is increased, which has detrimental effects on the heart. The arterial chemoreceptor activation plays an important role in stimulating renal SNA (RSNA) and muscle SNA in HF. We recorded CSNA and renal SNA (RSNA) in conscious normal sheep and in sheep with mild HF induced by rapid ventricular pacing (ejection fraction <40%). Tonic arterial chemoreceptor function was evaluated by deactivating chemoreceptors by supplementing room air with intranasal 100% oxygen (2‐3 L/min) for 20 min. In HF, chemoreceptor deactivation induced by hyperoxia reduced CSNA (90±2 vs. 75±5 bursts/100 beats, P<0.05; 86±5 vs. 66±7 bursts/min, P<0.001; n=10; hyperoxia vs. room air) and HR (96±4 vs 85±4 beats/min, P<0.001; n=12), but not RSNA burst incidence (93±4 vs 92±4 bursts/100beats; n=7), although due to the bradycardia RSNA burst frequency was decreased (90±8 vs 77±7 bursts/min; P<0.001). In normal sheep, chemoreceptor deactivation reduced HR without a significant effect on CSNA and RSNA. In HF, the response of CSNA, but not RSNA, to sodium cyanide injection was enhanced compared with normal sheep. There was no change in baroreflex control of HR, CSNA and RSNA either HF or normal sheep. In an ovine model of HF, tonic arterial chemoreceptor activation plays a critical role in stimulating the increased sympathetic activity to the heart.Grant Funding Source: Supported by NHMRC 628573, 07M 3293, 566819
Augmented hemodynamic response to insufficient sleep in women: response to a novel repetitive sleep restriction challenge (1171.4)
Authors: Yang Huan , Haack Monika , Surette Renata , Jabri Ingy , Mullington Janet 
Published: June 2021

Recent epidemiological studies demonstrate a consistent association between short sleep (i.e. self‐reported) and higher risk of hypertension. While this association seems to be stronger in women compared to men, the evidence from laboratory‐controlled studies is lacking. Thirty‐four healthy subjects (age 32±2 yrs; BMI 24±1 kg/m2; 18 men and 16 women) participated in a 22‐day in hospital study. Following 3 nights of adaptation sleep of 8h/night, subjects were randomly assigned to 4 cycles of repeated sleep restriction (4h of sleep/night for 3 nights followed by a night of 8h of sleep, repeated 4 times), or an 8h sleep control group. Blood pressure (BP) and heart rate (HR) were measured every morning at 8:30am and evening at 10pm in a seated position for 5 times over a 15min period. Morning BPs were not significantly different between sleep restriction and control groups in men or women (p>0.05). In contrast, women had significantly increased evening BP (i.e. up to 10±2mmHg in systolic BP, 5±2mmHg in diastolic BP) on the sleep restriction days compared to control (p=0.003 and 0.023 for systolic and diastolic BP, respectively). Moreover, repeated sleep restriction induced an increase in morning HR compared to control in women (p=0.005). Women show a pronounced pressor response to repeated challenges of sleep restriction, in a well‐controlled study.Grant Funding Source: Supported by NIH (HL‐106782)