bluuebunny/crossref_metadata_2025_split huggingface dataset:
Skeletal muscle immobilized in a stretched position does not display characteristics of disuse atrophy (1163.1)
Authors: Kelleher Andrew , Gordon Bradley , Luongo Lauren , Kimball Scot , Jefferson Leonard 
Published: June 2021

In a recent report we showed that skeletal muscle immobilized in a shortened position exhibits atrophy in association with reduced rates of protein synthesis and mTORC1 signaling. The objective of the present study was to test the hypothesis that, in contrast to the effects of immobilizing skeletal muscle in a shortened position, muscle immobilized in a stretched position would be resistant to the development of disuse atrophy. To test the hypothesis, male Sprague‐Dawley rats were subjected to unilateral hindlimb immobilization for 3 days with the soleus muscle placed in either a shortened or stretched position. All comparisons were made to the contralateral non‐immobilized muscle. Soleus muscles immobilized in a shortened position exhibited disuse atrophy, attenuated rates of protein synthesis, attenuated phosphorylation of Thr389 on the mTORC1 substrate p70S6K1, and induction of the mTORC1 repressors REDD1 and REDD2. Muscles immobilized in a stretched position exhibited no difference in muscle mass, rates of protein synthesis, p70S6K1 phosphorylation, or REDD1 expression and a slight reduction in REDD2 expression. In conclusion, fixed muscle length plays a major role in immobilization‐induced skeletal muscle atrophy whereby muscle placed in a stretched position exhibits resistance to disuse atrophy.Grant Funding Source: Supported by NIH Grant DK‐15658
Patients with chronic myosteatosis have a reduction in muscle fiber force production and disrupted myofibril architecture (1163.18)
Authors: Mendias Christopher , Roche Stuart , Davis Max , Lynch Evan , Bedi Asheesh 
Published: June 2021

A persistent atrophy of muscle fibers and an accumulation of fat, collectively referred to as myosteatosis, commonly occurs in patients with chronic muscle tears. The rotator cuff muscle group develops substantial myosteatosis after chronic tears, and patients with these injuries often have marked reductions in upper extremity function and quality of life. As the etiology of myosteatosis has not been well characterized in humans, our objective was to determine changes in muscle fiber structure and function in patients with chronic rotator cuff tears. We hypothesized that muscles from patients with chronic rotator cuff tears have reduced muscle fiber force production, disordered myofibrils and an accumulation of inflammatory macrophages.Compared with control muscles, there was no difference in muscle fiber cross‐sectional area, but torn supraspinatus muscles had a 30% reduction in maximum isometric force production and a 29% reduction in normalized force. Using electron microscopy and histology, disordered sarcomeres were noted, along with an accumulation of lipid‐laden macrophages in the extracellular matrix surrounding muscle fibers. The size of the tear correlated well (R2=0.49, P<0.01) with reductions in force production. The results of the study indicate that patients with myosteatosis have marked reductions in muscle fiber force production, disrupted myofibril architecture and an accumulation of inflammatory macrophages in the muscle extracellular matrix. This work will help to establish future therapies to restore muscle function for patients with myosteatosis.
Effects of a 6‐month trial of weight‐loss diet plus aerobic exercise versus matched (by dose/intensity) exercise alone on glucose tolerance and insulin resistance in subjects with pre‐diabetes (117.2)
Authors: Bales Connie , Starr Kathryn , Granville Esther , Slentz Cris , Bateman Lori , Willis Leslie , Piner Lucy , Kraus William 
Published: June 2021

The Diabetes Prevention Program first demonstrated benefits of lifestyle interventions for delaying progression of pre‐diabetes. Our study examines the separate effects of a weight‐loss diet plus exercise or exercise alone on oral glucose tolerance (OGTT) in a randomized 6‐mo. study of participants (age=57.8+7.6 y; BMI 30.6±2.9) with pre‐diabetes (fasting glucose 95‐124 mg/dL). Weight reduction diet + moderate aerobic exercise (D+Ex; n=41) was compared to a matched exercise program with no diet component (Ex; n=36). Baseline age, BMI, fitness level, and gender/race did not differ. D+Ex included a weekly support group and body weights (BW). Compliance with supervised exercise was similar for D+Ex and Ex (87.8% and 84.2%). At 6 mo., BW reductions in D+Ex (‐6.1+5.0 kg) exceeded (p<0.0001) those in Ex (‐0.9±3.3 kg). D+Ex improved (p<0.0001) fasting glucose (‐4.9±8.1 mg/dL), fasting insulin (‐3.5±3.8 mg/dL), 2‐hr glucose (‐20.5±35.9 mg/dL), HOMA‐IR (‐1.0±1.2) and glucose areas under the response curve. Ex, as well as D+Ex, improved (p<0.05) 2‐hr glucose, insulin area under the curve, and Matsuda Index. Weight loss plus exercise was superior for improving glucose tolerance/insulin resistance in this population. Thus, clinical recommendations for prediabetes should emphasize diet‐induced weight loss, along with exercise, as the first line of treatment. Grant Funding Source: Supported by NIDDK R01‐DK081559 and NIA AG000029.
Mechanisms mediating the muscle metaboreflex pressor response during post‐exercise muscle ischemia are altered in hypertension (1170.2)
Authors: Spranger Marty , Kaur Jasdeep , Sala‐Mercado Javier , Krishnan Abhinav , Alvarez Alberto , O'Leary Donal 
Published: June 2021

During dynamic exercise, muscle metaboreflex activation (MMA; induced via partial hindlimb ischemia) markedly increases mean arterial pressure (MAP) and MAP is sustained when the ischemia is maintained following the cessation of exercise (post‐exercise muscle ischemia ‐ PEMI). We previously reported that the sustained pressor response during PEMI in normal individuals is driven by a sustained increase in cardiac output (CO) with no peripheral vasoconstriction. However, we have recently shown that the rise in CO with MMA is significantly blunted in hypertension (HTN). The mechanisms sustaining the pressor response during PEMI in HTN are unknown. In six chronically instrumented canines, hemodynamic responses were observed during rest, mild exercise (3.2 kph), MMA and PEMI in the same animals before and after the induction of HTN (2K1C). In control, MAP, CO and HR increased with MMA (+52 ± 6 mmHg, +2.1 ± 0.3 l/min and +37 ± 7 bpm). After the induction of HTN (MAP at rest increased from 97 ± 3 to 130 ± 4 mmHg), these responses were markedly attenuated (+32 ± 5 mmHg, +0.6 ± 0.2 l/min and +11 ± 3 bpm), yet MAP was similarly sustained during PEMI while CO and peripheral vascular conductance were significantly lower (5.2 ± 0.2 l/min and 32 ± 3 ml/min/mmHg vs. 4.1 ± 0.4 l/min and 26 ± 2 ml/min/mmHg). We conclude that peripheral vasoconstriction significantly contributes to the sustained pressor response during PEMI in HTN.Grant Funding Source: HL‐55743 and HL‐095819
Inflammatory cytokines trigger SR/ER stress in human airway smooth muscle (1174.3)
Authors: Wallerich Samantha , Delmotte Philippe , Prakash Y.S. , Sieck Gary 
Published: June 2021

Airway inflammation is a key feature of asthma, with inflammatory cytokines (e.g., TNFα and IL‐13) triggering hyperreactivity (enhance contractile state) and proliferation and remodeling (enhanced synthetic state) in airway smooth muscle (ASM). We hypothesize that TNFα and IL‐13 induce sarcoplasmic reticulum/endoplasmic reticulum (SR/ER) stress, thereby altering expression of mitochondrial fission/fusion proteins (dynamin‐related protein ‐ Drp1 and mitofusin ‐ Mfn2) with downstream impact on ASM Ca2+ regulation and contractility as well as proliferation. Human ASM cells were isolated from lung specimens obtained incidental to patient surgery. We found that after 24 h exposing ASM cells to TNFα and IL‐13: 1) expression of SR/ER stress protein markers (PERK, calnexin and XBP1) increased; 2) Drp1 expression increased Mfn2 expression decreased; 3) mitochondrial fragmentation increased; 4) [Ca2+]cyt and [Ca2+]mito responses to ACh stimulation were uncoupled; 5) net [Ca2+]cyt increased; 6) contractility increased; and 7) cell proliferation increased. Together these results suggest that inflammation induces SR/ER stress that leads to changes in Mfn2 and Drp1 expression, which alter mitochondrial dynamics and Ca2+ regulation resulting in ASM hyperreactivity and remodeling.Grant Funding Source: Supported by NIH grant HL74309 (GCS)
Chronic hypoxia increases pro‐inflammatory TH17 cells via NFATc3‐induced interleukin 6 production in lung (1175.5)
Authors: Maston Levi , Reinhart Katelyn , Giermakowska Wieslawa , Nitta Carlos , Herbert Lindsay , Jernigan Nikki , Cannon Judy , Resta Thomas , González Bosc Laura 
Published: June 2021

We have demonstrated that the adaptive immune system along with nuclear factor of activated T cells isoform c3 (NFATc3) contribute to chronic hypoxia (CH)‐induced pulmonary hypertension (PH). NFATc3 regulates IL‐6 expression in multiple cells types. Considering that IL‐6 contributes to hypoxic PH and is required for polarization of naïve CD4+ T helper cells to the TH17 subset, we hypothesized that NFATc3 drives IL‐6 expression in pulmonary arterial smooth muscle cells (PASMC) contributing to CH‐induced increases in lung TH17 cells. Since TH17 cells are implicated in several cardiovascular diseases, these cells may play an unexplored role in PH. In support of our hypothesis, we found that IL‐6 transcripts as determined by real‐time PCR were increased in cultured mouse PASMC in which NFAT was activated with ionomycin and phorbol 12‐myristate 13‐acetate. This response was prevented by the calcineurin/NFAT inhibitor cyclosporine A and is consistent with our previous report demonstrating that CH activates NFATc3 in PASMC. Furthermore, lung TH17 cells as determined by flow cytometry were increased in male C57BL/6 mice exposed to 5 days of CH (PB=380 mmHg) compared to normoxic mice. This response was prevented by i.p. administration of a selective NFAT inhibitor (A‐285222, AbbVie). Our data suggest that CH‐induced PASMC NFATc3 activation and subsequent IL‐6 production contribute to increases in lung TH17 cells.Grant Funding Source: Supported by T32 HL07736, R01HL088151, R01 HL088192, R01 AI097202
Purinergic receptor stimulation induces Ca2+ oscillations and smooth muscle contraction in small pulmonary veins (1175.6)
Authors: Henriquez Mauricio , Perez‐Zoghbi Jose 
Published: June 2021

The small intrapulmonary veins (SPV) are thought to participate in the control of pulmonary blood flow and its excessive contraction has been associated with the development of pulmonary edema. However, the regulation of smooth muscle contraction by intracellular signaling in SPV is poorly understood. We used rat lung slices with phase‐contrast and confocal microscopy to investigate Ca2+ signaling and contraction during purinergic receptor activation in small (100‐250 µm) pulmonary veins. We found that ATP induced strong, concentration‐dependent, and reversible vein contraction. Vein contraction was accompanied by intracellular Ca2+ oscillations that propagated along the vein smooth muscle cell as Ca2+ waves. In the absence of extracellular Ca2+, ATP induced Ca2+ oscillations that were attenuated in time and transient vein contraction. The InsP3 receptor inhibitor 2‐APB inhibited the Ca2+ oscillations and contraction induced by ATP in absence of extracellular Ca2+. In contrast, Ca2+ oscillations and contraction were resistant to ryanodine. Vein contraction was inhibited by phospholipase Cβ inhibitor U73122 and by purinergic receptor antagonist suramin. These results suggest that ATP is a strong vasoconstrictor of SPV and that ATP activate purinergic P2Y receptors in vein smooth muscle to induce InsP3 receptor‐mediated Ca2+ oscillations and vein contraction.Grant Funding Source: American Heart Association
Combinatorial treatment with epigenetic modifiers inhibits thrombin‐induced eNOS/RhoA signaling and restores AJ integrity (1176.7)
Authors: Balasubramanian Sathyamoorthy , Thangavel Jayakumar , Dileepan Kottarappat N , Dhanasekaran Anuradha , Dawn Buddhadeb , Johnson Rajasingh 
Published: June 2021

Objective: Treatment of acute lung injury (ALI) is to target the pathways that lead to profound dysregulation of the restrictive endothelial barrier, and thereby restore lung microvascular endothelial barrier function and inhibit protein‐rich tissue fluid accumulation. Here we test the hypothesis that epigenetic modifiers TSA (Trichostatin‐A, HDAC inhibitor) and Aza (5‐aza‐2‐deoxycytidine, DNA methyl transferase inhibitor) together inhibit the thrombin induced eNOS/RhoA signaling and restore adherens junctions (AJs) integrity and diminished endothelial hyperpermeability.Results: The signaling, AJ integrity and endothelial permeability were assessed by RT‐PCR, immunofluoresence, Western analysis, and transendothelial resistance (TER). Our data show that combination of TSA+Aza is more effective in inhibiting thrombin‐induced lung hyperpermeability. We used an in vitro culture system of TER to determine the effect of TSA+Aza on thrombin‐induced change in resistance over the human pulmonary arterial endothelial cells. TSA+Aza treatment ameliorated the thrombin‐induced endothelial barrier disruption. The Western analysis data show that the treatment of TSA+Aza decreases the levels of thrombin induced RhoA and eNos signaling in lung endothelial cells.Conclusions: Our data indicate, for the first time, that TSA+Aza exert a protective role in preventing lung microvascular hyperpermeability and endothelial barrier disruption in thrombin‐induced lung injury, and thus have great potential as novel therapeutic agents
Alterations in Janus (JAK2)/signal transducer of activated transcription signaling pathway in human renal cell carcinoma (1179.2)
Authors: Banes‐Berceli Amy , Singhal Sara , Fulton Matthew , Geddes Timothy , Thibodeau Bryan , Wilson George , Hafron Jason 
Published: June 2021

RCC accounts for 9 out of 10 cases of kidney cancer. Approximately 65,150 new cases and 13,680 deaths are expected from this disease in 2013. There is urgent clinical need for better treatment options as RCC responds poorly to current chemotherapy. A major limitation to developing new treatments is that the molecular mechanisms responsible for inappropriate cell survival and chemoresistance are unknown. One pathway suggested to be involved in vitro is the JAK2/STAT. We hypothesized that there would be altered expression of the members and regulators of the JAK/STAT pathways in RCC. We utilized samples from normal (n=14), benign (n=6), and histological Fuhrman grades: Grade 1 (n=3), Grade 2 (n=10), Grade 3 (n=14), and Grade 4 (n=3). We analyzed 31 human RCC samples as well as the normal and benign samples with Affymetrix human gene microarrays and Western Blot technology. The samples were all clear cell renal carcinomas verified by a Beaumont Hospital pathologist. We analyzed 22,148 genes and altered gene expression was then detected by ANOVA taking into account histological stage. We found 170 genes that were differentially expressed in all grades compared to both normal and benign kidney samples. We found both JAK1 and JAK2 mRNA to be highly expressed in the RCC samples compared to the controls. We did not observe any decrease in the mRNA levels or protein expression of the regulatory proteins SOCS1, SOCS3 or SHP‐1. We did find an increase in SHP‐1 serine phosphorylation which is inhibitory in the RCC samples. These data suggest that altered function of the regulators not expression may be involved in RCC.Grant Funding Source: Zafarna Foundation
Lack of adenylyl cyclase 6 causes pseudohypoparathyroidism (1181.1)
Authors: Fenton Robert , Murray Fiona , Dominguez Rieg Jessica , Tang Tong , Levi Moshe , Rieg Timo 
Published: June 2021

Parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) enhance phosphate (Pi) excretion by the proximal tubule of the kidney via retrieval of the Na+‐dependent Pi transporters (Npt2a &amp; Npt2c). PTH activates adenylyl cyclase (AC) via PTH 1 receptors and stimulates cAMP/PKA signaling. However, the precise role and isoform(s) of AC in Pi homeostasis are unknown. We previously showed that mice lacking AC6 (AC6‐/‐) have increased plasma PTH and FGF23 while having comparable plasma Pi concentrations. Acute activation of the Ca2+ sensing receptor or feeding a zero Pi diet almost completely suppressed plasma PTH in AC6‐/‐ and wild‐type (WT) mice, indicating secondary hyperparathyroidism. We now studied the abundance and localization of Npt2a and Npt2c. Immunofluorescence and quantitative confocal laser scanning microscopy showed a reduced renal Npt2a and Npt2c protein abundance in AC6‐/‐ mice. Immunogold labeling indicated a tendency for a reduced total number of gold particles per proximal tubule cell in AC6‐/‐ mice (510±53 vs 715±119, P=0.09). In contrast to the Npt2a distribution under basal conditions in WT mice (53, 28 and 17% reside in microvilli, lysosomes and intracellular, respectively), in AC6‐/‐ mice the majority of Npt2a resides in lysosomes (12, 77 and 10%, respectively). The distribution of Npt2a gold particles 1h after PTH treatment (200 µg/kg) in WT mice was shifted, with less particles residing in the apical microvilli (24%) compared to lysosomes (40%) and intracellular compartments (40%) whereas the distribution in AC6‐/‐ was unchanged. We conclude that AC6 in the proximal tubule determines Npt2a trafficking and urinary phosphate excretion, such that AC6‐/‐ mice have pseudohypoparathyroidism.Grant Funding Source: P01 HL66941, HL088426, 1101BX001515, R01DK066029, P30DK079337 and 10SDG2610034
Acid activates ENaC and enhances salt taste in human subjects (1181.10)
Authors: Collier Daniel , Snyder Peter 
Published: June 2021

Blood pressure is dependent on the balance between Na+ intake and urinary Na+ excretion. In the kidney, ENaC regulates Na+ excretion. In the tongue, ENaC functions as a salt taste receptor, thereby contributing to the control of dietary Na+ intake. In previous work, we found that protons within the pH range of the kidney (pH 8.5‐5) reversibly stimulate ENaC. In the tongue, ENaC encounters extreme changes in pH—foods we ingest can be highly acidic (e.g. Coca‐cola is pH 2.2). We tested the effect of highly acidic pH (2.5) on ENaC activity. We expressed human ENaC (‐, ‐, and ENaC) in Xenopus oocytes and recorded ENaC Na+ currents. We found that pH 2.5 irreversibly increased ENaC current 2.2‐fold. To determine the mechanism, we performed single channel experiments. Channels treated with pH 2.5 showed an irreversible 2‐fold increase in open probability. Furthermore, we identified two residues in ENaC (Q371 and D376) that are required for acid activation. We hypothesized that activation of ENaC by acid would increase salt taste sensitivity. To test this, we measured the salt taste detection threshold in human subjects before and after lingual application of 10 mM H2PO4 (pH 2.2). We found that acid reduced salt detection threshold by 50%. Together, the data indicate that highly acidic pH irreversibly activates ENaC, resulting in enhanced salt taste. This may provide a physiological mechanism to regulate dietary Na+ intake.Grant Funding Source: Supported by NIH 2T32HL007121‐36 (DMC) and HL072256 (PMS)
Identifying transcriptional targets of vasopressin using combined ChIP‐seq and RNA‐seq analysis of mpkCCD cells (1181.6)
Authors: Claxton J'Neka , Sandoval Pablo , Lee Jae Wook , Hoffert Jason , Knepper Mark 
Published: June 2021

The peptide hormone vasopressin regulates transport in the renal collecting duct in part through regulation of gene expression. To obtain a global profile of genes regulated by vasopressin, we performed ChIP‐seq analysis of RNA polymerase II and acetylated histone H3K27 binding sites associated with transcriptionally active genes. Cultured mpkCCD cells were treated with either the vasopressin analog dDAVP (0.1 nM) or vehicle for 24 hours, and then processed for chromatin IP. DNA‐protein complexes were immunoprecipitated using either RNA pol II or H3K27ac antibodies. After reversal of crosslinks, DNA fragments were sequenced and mapped to a reference genome. ChIP‐seq data analysis allowed for precise mapping of genomic elements that were significantly enriched or de‐enriched with dDAVP treatment including exonic, intronic, intergenic, and promoter regions. We correlated these changes at the genomic level with corresponding changes in RNA using RNA‐seq analysis of ‘Poly(A)’‐enriched libraries from mpkCCD cells treated with or without dDAVP. Targets enriched in ChIP‐seq and RNA‐seq data sets in the presence of dDAVP included the water channel aquaporin‐2 (Aqp2), genes associated with AQP2 trafficking (Mal2) and AQP2 transcriptional regulation (Elf3), and many others. This study presents a wealth of new data needed for modeling the transcriptional response to vasopressin.Grant Funding Source: Supported by NHLBI
Immunohistochemical evidence of a reduced vasodilatory capacity in vertebrobasilar arteries in pre‐hypertensive spontaneous hypertensive rats (1183.9)
Authors: Roloff Eva , Kasparov Sergey , Paton Julian 
Published: June 2021

Our earlier work has shown that vertebrobasilar artery remodelling causing high vascular resistance occurs in SHR prior to the development of hypertension. We hypothesise that a component of this remodelling results from reduced capacity of the vasodilatory parasympathetic innervation and that this contributes to the etiology of neurogenic hypertension via Cushing’s mechanism. Whole mounts of brainstem ventral brain vessels from hypertensive SHR (<12weeks), PH‐SHR (P28‐35) and age‐matched Wistars were immunostained for dopamine‐β hydroxylase (DBH), vesicular acetylcholine transporter (VAChT) and vasoactive intestinal peptide (VIP); the latter is co‐expressed in parasympathetic fibres. We found an age dependent reduction in the parasympathetic (~60‐85%) and sympathetic (10‐40%) innervation density of vertebrobasilar arteries in SHRs compared to Wistar rats (p<0.001). VAChT positive fibre densities were ~30‐50% lower than VIP‐ in all rat groups. In conclusion, SHRs have fewer parasympathetic fibres innervating the vertebrobasilar arteries than Wistars. Given the higher prevalence of both VAChT and VIP in Wistar rats, we speculate that the vasodilatory capacity of these cerebral vessels in SHR will be compromised.Grant Funding Source: Supported by BHF, NIH
Quantifying autoregulation from estimated model parameters: an optimization approach (1184.8)
Authors: Simpson David , Henriques Berroeta Claudio , Katsogridakis Emmanouil , Panerai Ronney 
Published: June 2021

In order to quantify cerebral autoregulation (CA), one of the most commonly used techniques is to fit a linear model to the recorded signals, with arterial blood pressure (ABP) as input and cerebral blood flow velocity (CBFV) as output. Then parameters are extracted from the model to quantify CA: for example average phase or gain in a narrow frequency band, or features of the predicted step‐response. We propose an optimized method to distinguish between CA during normocapnia and hypercapnia. In 27 adults (18‐55 years old) at rest, CBFV and ABP were recorded simultaneously during normocapnia and then hypercapnia induced by breathing 5% CO2 in air. Recordings were repeated on a separate day, giving a total of 108 recordings of approximately 5 minutes each, all resampled at 1 Hz. The interrelationship between ABP and CBFV was modelled using a linear finite‐impulse‐response filter (7 coefficients). Multiple linear regression of these coefficients was used to predict normocapnia (1) or hypercapnia (0), achieving an area under the ROC curve of 0.91, considerably better than ARI (0.81) and slightly higher than for phase‐lead at 0.1 Hz (0.88). The method provides a new, data‐driven and optimized parameter for assessing autoregulation. This work is being extended to include non‐linear classifiers (support vector machines).Grant Funding Source: Supported by EPSRC (UK) and Central University, Chile