bluuebunny/crossref_metadata_2025 huggingface dataset:
Situs Inversus Totalis in a 96‐Year‐Old Female Cadaver: Genetic Insights
Authors: Jenkins Mia , Frolov Andrey , Tan Yun , Daly Daniel , Lawson Craig , Martin John
Published: June 2021

Background

Situs inversus totalis is a complete reversal of thoracic and abdominal organs. Since only 25% of individuals with situs inversus have primary ciliary dyskinesia (PCD), which is a genetically heterogeneous disorder affecting motile cilia and is thought to be one of the underlining mechanisms of situs inversus, the majority of the latter cases still await their mechanistic elucidation. The present study reports the complete reversal of internal organs in a female cadaver 96 years of age and uses state‐of‐the‐art Next Generation Sequencing (NGS) to detect novel genetic mutations associated with situs inversus totalis.

Results

Our examination of the individual's body revealed that the visceral organs of the abdomen and thorax were mirror‐imaged to normal anatomy. The apex of the heart was directed to the right with a trilobed left lung and bilobed right lung. The liver was situated on the left side of the body, while the spleen and stomach were right sided. Several abdominal vasculature anomalies were also identified. In particular, the common hepatic artery branches from the superior mesenteric artery and the cystic artery branches from the right hepatic artery. There was also a common trunk that gives off the left gastric artery and an accessory right hepatic artery. In order to gain new insights into the molecular mechanisms that govern determination of the left/right asymmetry during the internal organ development, the genetic screen was performed using DNA extracted from the cadaveric tissue and the exome sequencing on the Illumina NGS platform.

Conclusion

The present case can be described as situs inversus totalis which is accompanied by abnormal development of abdominal vasculature. The respective genetic analysis could point to a novel and additional to PCD mechanism(s) responsible for the aberrant visceral organ patterning and vascular development in humans.

Support or Funding Information

This study was supported by the Center for Anatomical Science and Education, Department of Surgery, Saint Louis University School of Medicine.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Sex Differences in Heart Rate Response to Isometric Handgrip Exercise with Concurrent Contralateral Forearm Somatosensory Stimulation
Authors: Jacobs Kaitlyn , Woerhle Emilie , Klassen Stephen , Smith Sydney , Barker Andrea , Knestch Rachel , Shoemaker J. Kevin
Published: June 2021

Background

Pharmacological evidence indicates that baseline cardiovagal mechanisms determine the rapid heart rate (HR) response to the onset of moderate intensity isometric handgrip (IHG) exercise. The HR response at exercise onset expresses sex differences, being less in females. Further, somatosensory nerve stimulation (STIM) appears to affect baseline cardiovagal control in some supine participants.

Objective

This study explored the effect of STIM on HR and heart rate variability (HRV) during short‐duration moderate‐intensity IHG in supine healthy adults and explored whether this effect expresses sex differences.

Participants

Twenty‐four young healthy individuals aged 23 ± 1.9 years (18 females (F): 165 ± 7.4cm, 63 ± 13kg, BMI 23 ± 2kg/m2; 6 males (M): 179 ± 2.2cm, 79 ± 11kg, BMI 25 ± 3.3kg/m2).

Methods

Participants performed six isometric handgrips with their right hand at 30 to 40% of their maximal grip strength, each lasting 20 to 30 seconds and separated by one minute of rest. Three of these IHG contractions were performed during simultaneous administration of sub‐motor STIM provided by transcutaneous electrical nerve stimulation (TENS; 100 Hz, 50 μs) on the medial contralateral forearm through anesthetized skin for the duration of the handgrip. A 3‐lead ECG provided R‐R interval data. Systolic (SBP) and diastolic blood pressure (DBP) were monitored, as well as, heart rate (HR), root mean square of successive differences in R‐R intervals (RMSSD) as a measure of HRV, and respiration. Data were analysed using two‐factor ANOVA with Bonferroni correction, and independent t‐tests.

Results

The ΔHR from baseline to IHG without STIM was greater in males compared to females (12 ± 6bpm versus 6 ± 6bpm, respectively; d = 1.00). No differences in ΔHR were detected for either sex when STIM was added to the IHG. Of the 18 F participants, 4 provided a minimal HR response (ΔHR > 4bpm) to the IHG without STIM (F1: 77 to 79bpm; F2: 69 to 70 bpm; F3: 50 to 50bpm; F4: 62 to 62 bpm) which resolved in 3 of the 4 F participants with application of STIM (F1:73 to 83bpm; F3: 45 to 59bpm; F4: 54 to 60bpm). Further, no statistically significant differences were observed in ΔRMSSD from baseline to IHG without STIM (p = 0.0321; M: 77 ± 68ms to 30 ± 145ms; F: 74 ± 38ms to 54 ± 39ms) and with STIM (p = 0.953; M: −28 ± 61ms and F: −30 ± 21ms).

Conclusion

Our preliminary findings suggest that, in supine individuals, sex differences exist in the HR response at the exercise onset but these effects are not modified by concurrent sub‐motor somatosensory nerve stimulation.

Support or Funding Information

Supported by Natural Science and Engineering Research Council of Canada

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
GABAergic Contribution to the Muscle Mechanoreflex‐Mediated Heart Rate Responses at the Onset of Exercise in Humans
Authors: Teixeira André L. , Ramos Plinio S. , Samora Milena , Sabino‐Carvalho Jeann L. , Ricardo Djalma R. , Colombari Eduardo , Vianna Lauro C.
Published: June 2021

It is well stablished that the cardiovascular response to exercise is governed by both central and peripheral mechanisms. However the possible neurotransmitters involved in the autonomic responses during exercise are not fully understood. During exercise, Potts et al. (Neuroscience 2003;119:201–14) showed that electrically evoked muscular contraction inhibits arterial baroreceptors signaling within the nucleus of the tractus solitaries (NTS) via activation of GABAergic receptors in rats, suggesting that skeletal muscle afferents are a potential source synaptic drive to GABAergic neurons within the NTS. However, the extent to which these findings can be extrapolated to humans remains unclear. We reasoned that the GABAergic mechanisms involved in the heart rate (HR) responses at the onset of dynamic exercise is primarily mediated by muscle mechanoreceptors afferents. Therefore, in this study we sought to determine if central GABA mechanisms are involved in the muscle mechanoreflex‐mediated HR responses at the onset of exercise in humans. Twenty‐eight healthy subjects (14 men) aged between 18 to 35 years randomly performed three bouts of 5‐s of passive and active cycling under placebo and following oral administration of diazepam (10 mg), a benzodiazepine that produces an enhancement in GABAA activity. Beat‐to‐beat HR (electrocardiography) and arterial blood pressure (BP ‐ finger photopletysmography) were continuously measured. Electromyography of vastus lateralis was obtained to confirm no electrical activity during passive trials. HR increased from rest under placebo and further increased following administration of diazepam in both passive (Δ12 ± 1 beats min−1 vs. Δ17 ± 1 beats min−1, P < 0.01) and active (Δ14 ± 1 beats min−1 vs. Δ18 ± 1 beats min−1, P < 0.01) cycling. Arterial BP increased from rest similarly during all conditions. Importantly, no sex‐related differences were found in any variables during all experiments. These findings demonstrate for the first time that the central GABAergic mechanisms significantly contribute to the muscle mechanoreflex‐mediated cardiac vagal withdrawal at the onset of exercise in humans.

Support or Funding Information

Brazilian National Council of Scientific and Technological Development (CNPq)

Foundation for Research Support of Federal District (FAPDF)

Brazilian Federal Agency for Support and Evaluation of Graduate Education (CAPES)

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Beta Adrenergic Induced Pulmonary Arterial Vasodilation Following Long Term Hypoxia in Fetal and Adult Sheep
Authors: Vazquez Ashley , Amen Marvin , Painter Brandon , Jalota Raveena , Blood Quinton , Zhang Lubo , Wilson Sean M.
Published: June 2021

Long term high altitude exposure is known to cause tissue hypoxia and exposure of fetuses as well as adults to rarefied environments increases morbidity and mortality. In particular, hypoxia can cause developmental abnormalities in the fetal pulmonary vasculature and contribute to pulmonary arterial hypertension in the adult. β2 adrenergic receptor (β‐AR) agonists are a major treatment for asthma, however far less is known about their role in pulmonary arterial function. Even still, previous evidence illustrates that β‐AR stimulation holds promise for the treatment of pulmonary arterial hypertension. Other evidence illustrates that β‐AR stimulation modulates the activity of Ca2+‐activated K+ channels (KCa), which are important mediators of pulmonary vasorelaxation. Dysregulation of KCa may contribute to chronic hypoxia induced pulmonary hypertension and β‐AR signaling may be involved in the process. In these studies we tested the hypothesis that β‐AR ‐ mediated pulmonary arterial vasodilation may be preserved following long term high altitude hypoxia due to dependency on KCa channels. This hypothesis was addressed in isolated pulmonary arteries from adult or fetal sheep that gestated at 700 meters (normoxic) or 3,801 meters for 110+ days (hypoxic). Myography was performed on pulmonary arterial rings to evaluate the vasorelaxation in response to the β‐AR agonist isoproterenol (ISO) and the methylxanthine phosphodiesterase inhibitor, IBMX. ISO‐mediated relaxation was preserved following hypoxia in fetal sheep and relaxation was greater in arteries from adult hypoxic animals relative to fetuses. Inhibition of BKCa with TEA blunted ISO‐mediated vasorelaxation in fetal normoxic and adult hypoxic arteries. IBMX caused a dose dependent relaxation in arteries from all groups and TEA did not influence this effect. Overall, these studies provide evidence that β‐AR stimulated pathways cause pulmonary arterial vasodilation, but with varying reliance on BKCa activation. Targeting β‐AR signaling pathways could therefore be therapeutically significant and functional alterations in the pathways may contribute to the development of disease.

Support or Funding Information

This material is based upon work supported by NIH HD‐069746, P01HD083132, and P20MD006988. MA and BP were Walter E Macpherson Medical Student Summer Research Fellows while AV was an Undergraduate Summer Research Fellow through the Center for Health Disparities and Molecular Mechanisms at Loma Linda University.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The Long Non‐Coding RNA XIST Is Decreased in Lungs and Plasma Exosomes of Sickle Cell Mice and in Hemin‐Treated Human Pulmonary Artery Endothelial Cells
Authors: Kang Bum‐Yong , Chang Sarah S. , Bedi Brahmchetna , Sutliff Roy L. , Archer David R. , Hart C. Michael , Sadikot Ruxana T.
Published: June 2021

Rationale

Pulmonaryhypertension (PH), a serious complication of sicklecell disease (SCD), causes significant morbidity andmortality. The release ofhemoglobin and free heme during hemolysis triggers endothelial dysfunction andcontributes to PH pathogenesis. Emerging evidence indicates that longnon‐coding RNAs (lncRNAs) play a pivotal role in cellular proliferation,differentiation, and apoptosis. Circulating exosomes, which are nano‐sized extracellular vesicles, contain lncRNAs and play an important role in intercellular communication. However, the role of lncRNAs released from lungs and plasmaexosomes in SCD‐PH pathogenesis has not been defined. We hypothesized that lncRNAs are differentially expressed in SSmouse lungs and plasma exosomes and in hemin‐treated human pulmonary artery endothelialcells (HPAECs).

Methods and Results

lncRNAs were isolated from lungs and plasma exosomes of sicklecell (SS) mice and littermate control (AA) mice at age 15–17 weeks. Isolated plasma exosomes were characterized forlevels of exosomal markers (CD9, CD45, and CD63), following which exosomes andlung samples were subjected to determine theexpression profiles of 90 lncRNAs using the LncProfiler™ lncRNA qPCR array(System Bioscienes). 5 lncRNAs were increased and10 lncRNAs were decreased in the lungs and plasma exosomes of SS mice compared to AA mice. One of thelncRNAs found to be decreased in SS samples was X‐inactivespecific transcript (XIST). To further examinewhether hemin reduces lncRNA XIST expression, HPAECs were treated with DMSO or hemin (5 uM) for 72 hours. XIST expression was decreased in hemin‐treatedHPAECs. Hemin also stimulated dose (0–10 μM)− and time (0–72hours)‐dependent increases in HPAEC monocyteadhesion and proliferation (BrdU assays). Because PPAR gamma (PPARg) levels were reduced in the lungs of SS mice,and pharmacological PPARg activation attenuated SCD‐PH, we examined the impactof PPARg activation on XIST levels in SS mouse lungs and found that PPARgactivation attenuates reductions in XIST expression.

Conclusions

Theseresults suggest that sickle cell disease can impact lncRNAs and these effectsmay be reversed by treatment with PPARg agonists. Therefore, characterizationof lncRNAs are impacted in SCD may provide new insights into SCD pulmonaryvascular dysfunction and PH pathogenesis and identify novel targets fortherapeutic intervention.

Support or Funding Information

Supported by NIH HL102167 (RLS and CMH) and NIH HL133053‐01A1 (BYK).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Increasing or decreasing the excitability of V2a neurons activates accessory respiratory muscles
Authors: Jensen Victoria N. , Seedle Kari , Turner Sarah M. , Crone Steven A.
Published: June 2021

Accessory respiratory muscles (ARMs) can be recruited to maintain respiration when the diaphragm is impaired or weakened, such as patients with Amyotrophic Lateral Sclerosis (ALS) or spinal cord injury. We chronically record mouse diaphragm electromyography (EMG), ARM EMG, and whole body plethysmography to assess the effect of activating and silencing V2a neurons with DREADDs on respiratory muscle activity and ventilation. Increasing the excitability of glutamatergic V2a neurons in the brainstem and/or the spinal cord recruits ARMs and enhances ventilation. Interestingly, silencing V2a neurons also activates ARMs. We hypothesize that V2a neurons participate in both excitatory and inhibitory pathways controlling activation of ARMs for breathing.

Support or Funding Information

University of Cincinnati T32 Training Grant 2016–2017

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Preliminary Phenotypic Cluster Analysis of Cardiorespiratory Modulated Neuronal Discharge Patterns with Dynamic Visualizations
Authors: MORRIS KENDALL F. , O'Connor Russell , Segers Lauren S. , Nuding Sarah C. , Horton Kofi‐Kermit , Alencar P. Ashley , Bolser Donald C. , Dick Thomas E. , Baekey David M. , Lindsey Bruce G. , Shuman H. Dale
Published: June 2021

Multi‐dimensional cluster analysis has been applied successfully to many taxonomy problems. Building on previous work (see Carroll et al., 2013 & Zuperku et al., 2015), we have developed a quantitative, reproducible clustering classification of respiratory neuron phenotypes based upon activity. We displayed the results with a multi‐factorial visualization tool.

We curated 100‐bin, normalized, cycle triggered histograms of spike trains with significant respiratory modulation (n=573 from a library of 1,373), recorded in lateral respiratory column (ventral respiratory group, pre‐Bötzinger, Bötzinger), pons, raphé, and dorsal lateral medulla. Initial analysis by Ward clustering with Cartesian distance in 100‐space differentiated three groups: predominantly inspiratory, predominantly expiratory and low respiratory modulation.

Subsequent application of the same clustering paradigm to each of these 3 groups yielded a preliminary set of 24 archetypes, the averaged histograms of the elements of each cluster. We used those archetypes as clustering centroids on naïve recordings of 229 spike trains; all were clustered, with 20 of the archetypes. A 3‐D brainstem atlas displayed neuronal firing rates during periods of control and/or stimulated activity such as chemoreception, cough, swallow and vagotomy; cell activity was colored by type (cluster), illuminated in proportion to firing rate, and could be displayed in stereo or as a side‐by‐side or differential comparisons of stimulated vs. control activity.

The data do not support a continuum of phenotypes based on discharge identity but instead are consistent with definable phenotypes.

Support or Funding Information

OT2OD023854, HL109025

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Lethal Avian Influenza A (H5N1) Virus Infects Pontomedullary Nuclei Containing Chemo‐sensitive Neurons to Induce Depressed Hypercapnic Ventilatory Response (dHCVR) in Mice
Authors: Zhuang Jianguo , Ye Chunyan , Xu Fadi
Published: June 2021

Highly pathogenic H5N1 (HK483) virus is neurotropic and lethal (~60% mortality in patients) mainly due to respiratory failure, but the relevant mechanisms are not fully understood. Our previous studies have shown that HK483 viral infection produces dHCVR 2–3 days and death 7 days post‐infection (dpi) in mice. This study aimed to determine the development of dHCVR from 2 – 6 dpi and the viral impact (6 dpi) on pontomedullary respiratory‐related neurons that potentially possess CO2‐chemoreception in the nucleus of solitary tract (NTS), the retrotrapzoid nucleus (RTN), raphe (ROb, RPa, and RMg), C1/2, A1 areas, and locus coeruleus (LC). Body temperature, weight, ventilation, and HCVR (7% CO2 for 5 min) were measured at 0, 2, 4, and 6 dpi in Ctrl and HK483 viral infected awake mice followed by collecting arterial blood after anesthesia. Subsequently, the brainstem sections were immunohistochemically processed to detect the nucleoprotein of H5N1 influenza A (NP) coupled with immunoreactivity (IR) of SP, NK1R, tyrosine hydroxylase (TH, a marker of catecholaminergic neuron), or tryptophan hydroxylase (TPH, a marker of serotonergic neuron). HK483, compared to Ctrl, mice showed gradually aggravated body weight loss, hypothermia, and dHCVR. HK483 viral infection strikingly enhanced SP‐IR expression in the NTS. Among the neurons expressing: 1) NK1R in the NTS and RTN; 2) TH‐IR in C1/2, A1 areas, the NTS, and the LC; and 3) TPH in raphe, co‐labeling with NP was found up to 50%, 30%, and <10%, respectively. Moreover, the NK1R and TPH‐IR in these regions were significantly lower in HK384 than Ctrl mice. We conclude that HK483 virus is capable of invading the pontomedullary respiratory nuclei, particularly those neurons expressing NK1R or TPH to suppress their expressions, which likely contributes to dHCVR and the subsequent death.

Support or Funding Information

HL119683

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Fractones and basement membranes for the mathematical modeling of tissue growth and regeneration.
Authors: Fronville Alexandra , Ballet Pascal , Beros Achilles , Chyba Monique , Mercier Frederic
Published: June 2021

Biological growth can be defined as a set of processes that cause tissues or organs to develop and maintain. When simulating this growth in DynCell, a C++ virtual reality simulator, questions arise about how the shape is controlled and maintained in a stable state whilst cells renew. In order to understand tissue growth, we elaborated a mathematical model based on viability theory and morphological analysis. In our model, each cell is defined as a control system. Moreover, each cell includes the same genetic information, which can lead to differentiated cell types. Cells interact with each other during the growth process and take decisions on their fate (cell division, differentiation, migration or apoptosis) according to the genetic information, the position of the other cells and the micro‐environmental cues provided by the extra cellular matrix. From a mathematical point of view, cellular division implies a multi‐valued dynamic. To formalize this dynamic, we have used mutational equations instead of differential equations usually utilized for classic dynamical systems. Cells successively divide according to a controlled topology, and ultimately generate the shape of the organism. This shape reaches a morphological equilibrium, up to a time horizon. To attain a defined topology, it is essential to control cell polarization and cell division. In biological organisms, this control is performed by fractones, extra‐cellular matrix structures anchored near the surface of the cells. Fractones contains heparan sulfate proteoglycans (HSPG) that bind, concentrate and dispatch growth factors to the target cells to ultimatly control cell proliferation and differentiation. Fractones constantly change their HSPG motives to bind different growth factors that either promote or inhibit stem cell proliferation and differentiation. The role of fractones as captors or activators of growth factors ultimately permits biological construction in a much finer mode than with simple reaction‐diffusion models. Using our fractone model, it is possible to generate and renew shapes throughout the tissue except at the interface of tissue layers. Indeed, we have found that our model is not sufficient for cells bordering tissue layers. Therefore, we hypothesize that basement membranes, i.e. specialized coats of extracellular matrix, chemically similar to fractones, become the leading components that control cell proliferation and the layout interface between organized tissues. In conclusion, our model strongly suggests that basement membranes and fractones are essential for the proper control of development and maintenance of biological organisms.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Diastolic overstretch causes inner mitochondrial collapsing and impaired force generation in isolated rat papillary muscle
Authors: Minamisawa Susumu , Nishioka Naritomo , Usui Fumio , Kusakari Yoichiro
Published: June 2021

Objectives

Ventricular volume overload is a cause of heart failure. However, the effect of volume overload on inner‐cellular organelles are incompletely understood. We investigated the functional and morphological changes in cardiac papillary muscle by diastolic overstretch with isometrical contraction.

Methods and Results

We used male SD‐rats (BW > 350 g) and dissected papillary muscle from the right ventricle. A papillary muscle preparation was mounted in a bath chamber and stretched to L max, at which active tension reached to the maximal level. We then stretched to 110% of Lmax (mild overstretched; mild‐OS) or 120% of Lmax (severe overstretched; severe‐OS), and stimulated papillary muscle (1 Hz, 36°C) for 4 hours with tension measurement. They were then compared with Lmax group (non overstretched; non‐OS). The active tension was immediately decreased after overstretch to 67.8±3.8% (n=6) of the non‐stretched condition in mild‐OS and to 17.3±4.0% (n=5) of the non‐stretched condition in severe‐OS. The active tension was gradually decreased with time in all preparations. After measurement of tension, papillary muscles were fixed with 2% glutaraldehyde by carefully keeping their overstretched position. We performed electron‐microscopic (EM) study and analyzed the changes in sarcomere length and morphological changes in organelles including myofilaments and mitochondria in non‐OS, mild‐OS, and severe‐OS. In mild‐OS, the sarcomere length was stretched to 2.41 mm which was comparable for 112% overstretch of non‐OS sarcomere length. In severe‐OS, the sarcomere length was stretched to 2.53 mm which was comparable for 118% overstretch. Nevertheless, the sarcomere structure of OS papillary muscles remained organized well. On the other hand, inner mitochondria density was lower in mild‐OS. Moreover, we found inner mitochondrial collapsing in severe‐OS. The EM study suggested that mitochondria were fragile under mechanical stress, such as diastolic overstretch, compared with muscle fibers and other organelles.

Conclusion

Overstretch of a rat isolated rat papillary muscle caused inner mitochondrial collapsing in a stress‐dependent manner. Those acute morphological changes in mitochondria by diastolic overstretch would be one of the mechanisms on pathogenesis of volume overloaded heart failure.

Support or Funding Information

This work was supported by grants from the Ministry of Education, Culture, Sports, Science and Technology of Japan (15K08190).
Interleukin 13 Promotes Cardiomyocyte Proliferation and Heart Regeneration In Vivo
Authors: Paddock Samantha J. , Wodsedalek Dylan , Kenarsary Aria , Flister Michael J. , O'Meara Caitlin C.
Published: June 2021

Aims

Preliminary data shows that the cytokine interleukin 13 (IL13) can promote neonatal mouse cardiomyocyte (CM) proliferation in vitro. From this, we hypothesize that IL13 and its downstream signaling pathway(s) play a role in stimulating mammalian heart cell cycle activity in vivo. We aim to test the role of endogenous, and exogenously administered, IL13 in promoting cardiomyocyte cell cycle activity and heart regeneration in vivo.

Methods and Results

To understand if IL13 could promote CM proliferation in vivo, we collected whole hearts from C57/BL6J and IL13−/− neonatal mice. Heart halves were saved for histology and immunohistochemistry (IHC) and ventricle pieces for RNA extraction and protein lysates. To measure proliferation, we sectioned neonatal hearts for IHC and stained them with Proliferating Cell Nuclear Antigen (PCNA) or Phosphorylated Histone H3 (pH3). To ensure the proliferating cells were CM specific, we dual‐stained PCNA with Myocyte Enhancer Factor 2C (Mef2C) and pH3 with Cardiac Troponin T2 (cTnnt). We found CMs in IL13−/− mice show a decrease in PCNA when compared to BL6 wildtype CMs, indicative of decreased proliferation in the absence of IL13. When analyzed by qRT‐PCR, our IL13−/− mice also showed an increase in hypertrophic markers, specifically Brain Natriuretic peptide (nppb). Nppb is primarily expressed by the heart ventricles upon myocardial stretch and is shown to be upregulated during heart failure. Additionally, we found that by administering recombinant IL13 (rIL13) to the IL13−/− mice, we were able to rescue some of these phenotypes, namely increasing PCNA‐ and pH3‐positive CMs and decreasing nppb expression. To elucidate the downstream signaling pathways of IL13, we treated cultured neonatal rat CMs with rIL13 or no treatment. We preformed western blot and RNAsequencing on these CMs treated with rIL13 and both of these methods indicated a strong initial activation of Erk1/2 and Akt signaling pathways.

Conclusions

Our data suggests that endogenous and exogenously administered IL13 can promote CM cell cycle activity. IL13−/− mice show decreased levels of CM proliferation, which was in part rescued when administered rIL13. We also found that rIL13 treatment in CMs activates Erk1/2 and Akt pathways, which have been shown to be pro‐proliferative and pro‐survival in CMs, respectively. In the future, IL13 and its corresponding signaling pathways could potentially be targeted to promote pro‐regenerative therapies in cardiac tissue.

Support or Funding Information

American Heart Association

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
LAT1 Promotes Angiogenic Responses in Human Endothelial Cells
Authors: Durante William , Liu Xiao‐ming , Peyton Kelly J.
Published: June 2021

L‐type amino acid transporter 1 (LAT1) is a sodium‐independent high‐affinity transporter of large neutral amino acids, such as L‐leucine. LAT1 is abundantly expressed in a wide range of tumor cells but displays a more restricted pattern of expression in non‐transformed cells. We previously reported that LAT‐1 is present in vascular smooth muscle cells and that it plays a fundamental role in cell proliferation and survival. Since vascular endothelium also expresses LAT1, the present study investigated the functional activity and significance of this transporter in cultured human umbilical vein endothelial cells (ECs). We found that the transport of radiolabeled‐leucine by ECs was time‐dependent and linear for up to 5 minutes. The endothelial uptake of leucine was not dependent on sodium or pH, and was strongly inhibited by neutral, but not basic or acidic amino acids. Leucine transport was also abolished by the selective inhibitor of system L transport, 2‐amino‐2‐norbornanecarboxylic acid (BCH). Interestingly, blockade of leucine transport by BCH was associated with a striking concentration‐ and time‐dependent decrease in EC proliferation and DNA synthesis. Cell cycle analysis found that BCH arrested ECs in the G0/G1 phase of the cell cycle. Furthermore, EC migration following scrape injury was significantly attenuated by BCH. Moreover, the formation of endothelial tubes following the plating of ECs onto matrigel was markedly reduced by BCH. Finally, ex vivo treatment of mouse aortic rings with BCH diminished EC sprouting from these rings. In conclusion, this study demonstrates that ECs exhibit LAT1 activity, and that LAT1 plays an essential role in stimulating EC proliferation, migration, and tube formation. In addition, it identifies LAT1 as an attractive therapeutic target in treating angiogenesis‐dependent disease.

Support or Funding Information

Supported by the NIH Grant HL‐59976.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The Impact of Acute Tetrahydrobiopterin Administration on Plasma Adropin Concentration in Patients with Systemic Sclerosis
Authors: Clifton Heather Lynn , Kwon Oh Sung , Machin Daniel R. , Layec Gwenael , Richardson Russell S. , Frech Tracy M. , Donato Anthony J. , Wray D. Walter
Published: June 2021

Background

Systemic sclerosis (SSc) is an autoimmune disease characterized by inflammation, fibrosis, and profound vascular dysfunction. Adropin, a protein encoded by the Energy Homeostasis Associated gene (ENHO), has recently been shown to have direct effects on endothelial function [1], and as such, has been identified as a novel therapeutic target for treatment of vascular dysfunction. Our group has previously reported that administration of tetrahydrobiopterin (BH4) improved vascular function in SSc patients [2], ostensibly through its role as an essential endothelial nitric oxide synthase (eNOS) cofactor. However, the impact of BH4 administration on other related pathways has not been thoroughly investigated. Therefore, the aims of this study were (1) to determine if plasma adropin concentration differed between SSc patients and healthy controls, and (2) to assess the impact of acute oral BH4 administration on plasma adropin concentration in SSc patients.

Methods

Thirteen SSc patients (4 male, 9 female; age 60 ± 3 yrs; ht 171 ± 3 cm; wt 76 ± 4 kg) and 15 healthy controls (4 male, 11 female; age 62 ± 3 yrs; ht 163 ± 2 cm; wt 62 ± 3 kg) participated in this study. Venous blood samples were taken following a 5 hour fast. SSc patients consumed either BH4 (10 mg/kg) or placebo in randomized order 5 hours prior to arrival at the laboratory. Plasma adropin concentration was assessed by means of an enzyme‐linked immunosorbent assay kit (ELISA; Phoenix Pharmaceuticals, Inc., Burlingame, CA).

Results

Plasma adropin concentration was significantly lower in SSc patients compared to healthy, age‐matched controls (1.98 ± 0.02 vs. 2.07 ± 0.03 ng/mL, p=0.02). In SSc patients, plasma adropin concentration increased following acute BH4 administration (1.98 ± 0.02 to 2.00 ± 0.01 ng/mL, placebo vs. BH4, p=0.05), a restoration that neared values observed in the control group (p=0.06, SSc BH4 vs. control).

Conclusions

SSc patients demonstrate a disease‐related reduction in plasma adropin concentration that can be increased by acute BH4 administration, rescuing adropin levels to near that of healthy controls. Together, these findings suggest that adropin may represent a novel therapeutic target in SSc, though further investigation is needed to explore the mechanisms by which BH4 may alter this pathway and subsequently impact endothelial function.

Support or Funding Information

Funding: This project is funded in part by the National Institutes of Health (HL118313) and the U.S. Department of Veterans Affairs (RX001697, RX001418, E6910R).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Diabetic heart failure patients demonstrate a mitochondrial complex I dependent impairment in skeletal muscle
Authors: Garnham Jack , Boyle John , Roberts Lee D. , Peers Chris , Kearney Mark T. , Bowen T. Scott , Witte Klaus
Published: June 2021

Heart failure (HF) is characterised by exercise intolerance and high mortality – both of which are exacerbated in patients with concomitant type 2 diabetes (DHF). However, cardiac dysfunction remains similar between HF and DHF patients, suggesting peripheral mechanisms may be playing a key role in the DHF phenotype. This study, therefore, aimed to explore whether a skeletal muscle specific myopathy may be present in patients with DHF compared to HF alone.

Skeletal muscle biopsies were sampled consecutively from pectoralis major in age‐matched healthy controls (n=25), HF (n=52), and DHF patients (n=28). Mitochondrial O2 consumption and H2O2 flux (i.e., an index of mitochondrial ROS) were measured in saponin‐permeabilized fiber bundles (Oroboros, Innsbruck, AT). Fiber type (I and II) and size were further assessed using standard histology.

Peak oxygen uptake was reduced in DHF compared to HF and control patients (12.7±0.4 vs. 15.9±0.5 and 17.5±1.2 mL/kg/min); P<0.05), while left ventricular ejection function was similar between DHF and HF patients (29±2 vs 29±1%; P>0.05). In contrast, skeletal muscle tissue showed significant impairments specific to DHF patients, particularly in relation to mitochondrial function: complex I respiration was impaired by 49 and 62 % compared to HF and controls (P<0.05), which was inversely correlated (R2=0.28, P<0.05) to increased complex I H2O2 flux. The respiratory control ratio (RCR) was also reduced (P<0.05) in DHF by 18 and 16% compared to HF and control patients. Citrate synthase activity, an index of mitochondrial content, was reduced in both HF groups compared to controls on average by 37%, but without any additional diabetic‐specific effects (P>0.05). Fiber structural alterations (size and type) remained unchanged between groups (P>0.05).

In conclusion, these data provide novel evidence that skeletal muscle mitochondrial complex I function is worse in patients with DHF compared to HF alone. This impaired mitochondrial respiration in DHF patients was closely associated with increased mitochondrial ROS production, but without similar reductions in mitochondrial content suggesting the locus of limitation is qualitative. Collectively, therefore, these data provide preliminary evidence that a skeletal muscle myopathy contributes to the DHF phenotype.

Support or Funding Information

Multidisciplinary Cardiovascular Research Centre (MCRC), Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, UK

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Glucose‐6‐Phosphate Dehydrogenase Regulate Metabolome‐Transcriptome Axis And Mitochondrial Malfunction In Diabetic Hearts: Implications In Pathogenesis Of Diabetic Cardiomyopathy And Mending Of Broken Hearts
Authors: Dhagia Vidhi , Joshi SachindraRaj , Soldatos Vasiliki , Rocic Petra , Edwards John , Gupte Sachin
Published: June 2021

Rationale

Cardiovascular performance and the progression of heart failure is worse in patients with metabolic syndrome or type II diabetes mellitus (T2DM) than in non‐diabetics. We hypothesized that increased glucose‐6‐phosphate dehydrogenase (G6PD) activity in the diabetic heart alters the transcriptome and metabolome profile and impairs mitochondrial function, leading to decreased myocardial function.

Methods and Results

We used hyperglycemic Goto‐Kakizaki (GK) rats fed a normal chow (NC) or a high fat diet (HFD) and JCR rats, a model of metabolic syndrome (MetS). Hemodynamics were evaluated through cardiac catheterization and metabolite profiling, and transcriptome analysis was used to detect molecular signatures underlying the disease condition. We found that cardiac contractility was decreased in GK‐NC and GK‐HFD rats, but left ventricular stiffness was increased only in GK‐HFD rats. In those hearts, G6PD activity was increased, and the G6PD activity correlated negatively with mitochondrial cytochrome c oxidase (COX) activity. Also increased was the expression of voltage‐dependent anion channel (VDAC), which was associated with increased cardiac cytosolic cytochrome c expression GK rats. In vitro experiments showed VDAC is regulated by miR‐31. Administration of epiandrosterone (30 mg/kg/day s.c.), a well‐known G6PD inhibitor, to JCR rats for 28 days increased fractional shortening, decreased LV stiffness, and attenuated fibrosis and neointimal growth in the coronary arteries as compared to vehicle treatment. This was accompanied by decreases in VDAC and increases in miR‐31. Metabolomic and transcriptomic analysis revealed that G6PD inhibition reversed MetS‐induced cardiac metabolic reprogramming and gene expression.

Conclusion

These findings suggest that increased G6PD activity suppresses mitochondrial respiratory chain enzymes, induces maladaptive overexpression of mitochondrial proteins through miR pathways, and evokes left ventricular stiffness in diabetic rats fed a HFD. Moreover, inhibition of G6PD reverses the fibrosis, metabolic reprogramming, and gene expression changes seen in hearts from diabetic and MetS animals.

Support or Funding Information

NIH RO1 HL 132574 (SAG)

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Force‐frequency Relationship and Early Relaxation Kinetics Are Preserved Upon SR Blockade in Human Myocardium
Authors: Chung Jae‐Hoon , Canan Benjamin , Whitson Bryan , Kilic Ahmet , Mohler Peter , Janssen Paul
Published: June 2021

Cardiomyocytes utilize calcium to activate their myofilaments and shorten, which at the organ level results in blood being pumped out of the heart and into the body. Sarcoplasmic reticulum (SR) is an organelle in cardiomyocytes that stores calcium ions and releases them during systole, when myofilament needs to be activated and sequesters them during diastole, when myofilament needs to be deactivated. Therefore, it is believed to play an integral role in the calcium handling of cardiomyocytes with potential implications in the force‐frequency relationship, as intracellular calcium is increased at higher heart rates. However, the SR is believed to be less important in calcium handling in larger mammals, which have sodium calcium exchangers (NCX) that can extrude calcium out of cardiomyocytes. We hypothesized that when the SR is blocked in human trabeculae, the relaxation function would not be affected and that force‐frequency relationship would be preserved. We isolated intact human right ventricular trabeculae from non‐failing and failing human hearts and measured various contractile and relaxation parameters upon SR blockade. We found that force‐frequency relationship is preserved even when the SR is blocked. We also found that early relaxation speed is not affected when the SR is blocked, probably because of NCX compensating for the lack of SR function. Moreover, we found that the contraction kinetics are slower upon SR blockade, potentially because L‐type calcium channel, which have slower calcium‐release kinetics than the SR, compensates for the lack of SR calcium release

Support or Funding Information

R01 HL113084 to Paul ML JanssenAHA 16PRE33410549 to Jae‐Hoon Chung

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
New RiPP family incorporates alpha‐N‐methylations into ribosomally encoded peptide natural products
Authors: Freeman Michael
Published: June 2021

Microorganisms communicate using the molecular language of natural products. Amazingly, the vast majority of microorganisms on Earth are as‐of‐yet uncultivated or too difficult to genetically manipulate and directly study. Thus, the discovery of new natural products or description of new biocatalytic transformations occurring within NP pathways from these niche microbial sources often require heterologous expression in tractable microbes. This work describes the unexpected biosynthetic origins of a ribosomally synthesized and post‐translationally modified peptide (RiPP) produced by a basidiomycete fungus. We provide evidence, through heterologous expression, for iteratively incorporated alpha‐N‐methylations into a ribosomally encoded precursor protein. This never‐before‐seen post‐translational modification was thought for over forty years to be only accessible through nonribosomal peptide synthesis. Along with a very unusual leader peptide composition, this pathway hallmarks the designation of a new RiPP natural product family we termed borosins. We go on to show this borosin RiPP family can be easily engineered to create new alpha‐N‐methylated peptides in vivo through genetic recoding, a first for this type of tailoring reaction. This research adds to the handful of RiPPs so far discovered or described in fungi and highlights the vast metabolic potential of uncharacterized microorganisms.

Support or Funding Information

University of Minnesota

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Mathematical modeling of left ventricle hypertrophy and dilatation in response to volume overload in heart failure: a coupled renal‐cardiac model
Authors: Anjum Sommer , Jajamovich Guido , Allen Richard , Sher Anna , Dockendorf Marissa , Musante Cynthia J. , Hallow K. Melissa
Published: June 2021

It is well‐established that the heart remodels in response to changes in mechanical loads, and mathematical modeling of cardiac function and remodeling is an advanced field. However, volume regulation is a critical component in the pathogenesis, progression, and management of congestive heart failure, and few existing models account for the interaction between cardiac function and volume regulation by the kidney and neurohumoral signaling. A primary failure in cardiac function is compounded by volume retention as the heart and kidney work together to try to maintain organ perfusion. Eccentric hypertrophy occurs in response to volume overload, as increases in ventricular filling pressure elevate stress and stretch experienced in myocytes during diastole is believed to cause the series replication of sarcomeres and chamber enlargement. In this study, we utilized a coupled model of cardiac mechanics [1] and renal function, volume regulation, and the renin‐angiotensin‐aldosterone system[2]. We previously expanded the model to include mechanisms of cardiac hypertrophy and wall thickening in response to pressure overload – a self‐limiting process. We have now also incorporated a mechanism for left ventricle dilatation in response to volume overload, a progressive process. Specifically, myocyte length is modeled as a function of end‐diastolic myocyte stress, a relationship governed by a time constant. The model reflects the expected behavior of heart failure patients: reduced ejection fraction and increased left ventricle end diastolic volume, stress, and pressure. After inducing “heart failure” by reducing cardiac contractility, we used temporal pressure‐volume data from heart failure patients in the SOLVD study to ensure that the model accurately reflects the structural and hemodynamic changes characteristic of heart failure. We also used published data to establish an empirical relationship between left ventricle End Diastolic Stress and n‐Type Brain Natriuretic Peptide (NT‐pro BNP). We then validated the model by simulating and showing agreement with changes in the pressure‐volume loop in response to enalapril treatment in SOLVD, and NT‐proBNP at baseline and after treatment with valsartan in the VALHEFT[4] trial. This model improve our understanding of the hemodynamic interactions between renal and cardiac function and volume homeostasis in disease, and is a step toward in silico evaluation of new therapeutic mechanisms.

Support or Funding Information

This work was funded by collaborative grant from Pfizer Worldwide Research & Development and Merck & Co., Inc.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Activation of Renin‐Angiotensin Aldosterone System's Effect on Protein Disulfide Isomerase
Authors: Veliz Kenny , Cazares Joshua , Rivera Alicia , Ortiz Rudy , Romero Jose
Published: June 2021

Disordered activation of the Renin‐Angiotensin‐Aldosterone‐System (RAAS) is associated with hypertension and insulin resistance. The hormones Angiotensin II (Ang II) and Aldosterone (Aldo) are two of its principal effector molecules that have been shown to regulate sodium and volume homeostasis leading to blood pressure control. Ang II has been shown to activate endothelial cells and increase the secretion of extracellular protein disulfide isomerase (PDI). PDI is a multifunctional protein critical to thrombus formation and regulation of reactive oxygen species among other functions. Our group has recently reported that caloric restriction (CR) in rodents leads to increases in Aldo secretion from adrenal zona glomerulosa cells. However, the effects of CR on PDI are unknown. We hypothesize that CR, due to its association with activating RAAS, will lead to increases in the circulating PDI activity. To test our hypothesis, we propose to study the in vitro effects of AngII and Aldo on PDI activity. We will study the in vivo effects of CR on the circulating activity of PDI in Long‐Evans Tokushima Fatty (LETO) and Otsuka Long‐Evans Tokushima Fatty (OLETF). We use two assays to measure PDI activity. In one approach we will use insulin degradation assays. The measurement of circulating PDI activity will be further validated with a fluorescent of Di‐E‐GSSG assay. Initial studies have shown specificity of our assay using the insulin degradation assay and recombinant PDI. Controls of our fluorescent assay are currently underway. We expect that CR will be associated with increased PDI activity.

Support or Funding Information

K.V. is supported by an NIH MARC grant R25HL121029 and by the Division of Medical Sciences.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.