bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single cardiac myocytes from the left and right ventricles respond similarly to isoproterenol and omecamtiv mecarbil
Authors: Buckley Tori Dawn , Isaac Joslyn , Campbell Kenneth S. 
Published: June 2021

The left and right cardiac ventricles develop from different embryonic structures and generate different systolic pressures in vivo (left ventricle ~120 mm Hg, right ventricle, ~25 mm Hg). Some patients also develop chamber‐specific hypertrophy. We measured the contractile properties of cells isolated from the left and right ventricles of rat hearts and tested how they responded to omecamtiv mecarbil and isoproterenol. Based on data from ongoing experiments using human samples in our laboratory, our hypothesis was that cells from the left and right ventricles would exhibit similar contractile effects. Cells were isolated from 3 to 6 month old female Sprague Dawley rats by enzymatic digestion. Shortening profiles and calcium transients were measured at 32°C using video microscopy and Fura2‐AM fluorescence respectively. Statistical tests were performed using linear mixed models. A total of ~150 cells were analyzed using isoproterenol concentrations ranging from 0 to 1.0 μM and omecamtiv mecarbil concentrations ranging from 0 to 10.0 μM. We measured 22 parameters quantifying various aspects of the Ca2+ transients and shortening profiles (e.g. time to peak, amplitude, etc.) Although some statistical tests produced p values less than 0.05 for region, no systematic differences were observed between cells from the left and right ventricles. Our conservative interpretation is that single cardiac myocytes from the left and right ventricles have similar contractile properties. The different pressures generated by the two ventricles probably reflect differences in chamber structure and wall thickness as opposed to differences in the contractile properties of the myocytes themselves.Support or Funding InformationAHA GRNT2546003, NSF 1538754, NIH TR000117, APS STRIDE, APS UGSRF, HL115473.
Nutrient sensing and mitochondrial coenzyme Q biosynthesis: Are they connected by a phosphatase?
Authors: Awad Agape M. , Venkataramanan Srivats , Nag Anish , Bradley Michelle C. , Galivanche Anoop R. , Johnson Tracy L. , Clarke Catherine F. 
Published: June 2021

Coenzyme Q (also termed ubiquinone or Q) is an electron carrier in the mitochondrial respiratory chain that functions as an essential component in energy metabolism processes. Q transfers electrons from NADH and succinate to cytochrome c, a heme protein, and also serves as a vital lipid soluble antioxidant. Sufficient de novo Q biosynthesis is crucial for human health. Saccharomyces cerevisiae (baker's yeast) serves as an excellent model for studies on Q because of its powerful molecular genetics and the functional identity of yeast and human COQ genes in Q biosynthesis and function. Coenzyme Q biosynthesis in S. cerevisiae (which makes Q6 with six isoprene units, versus Q10 in humans with ten isoprene units) takes place in the mitochondria and, currently, thirteen known mitochondrial proteins are responsible for facilitating this process—Coq1‐Coq11, Yah1 (ferredoxin), and Arh1 (ferredoxin reductase). Many of the proteins necessary for the biosynthesis of Q6 associate in a high molecular weight complex (termed the “CoQ‐Synthome”) that localizes in the inner mitochondrial membrane. Previous work indicated that the stability of the Q biosynthetic complex relied on the presence of Coq8, the putative kinase of the system. In addition, several Coq polypeptides are phosphorylated in a Coq8‐dependent manner, including Coq3, Coq5, and Coq7, and potentially Coq6. Thus, the role of phosphorylation, as it pertains to Q biosynthesis and regulation, may provide novel information as to how the CoQ‐synthome is regulated. Additionally, intriguing links have been discovered that relate Coq polypeptides and phosphorylation status with nutrient availability and regulatory genes. Hence, our objectives are to investigate these links further and discover new information related to regulation by phosphorylation of the CoQ‐Synthome. Such studies will aid our understanding and treatment of multiple diseases caused by CoQ‐deficiencies and will provide novel insight in longevity and issues related to aging in humans. This research was supported by NSF MCB‐1330803.Support or Funding InformationNSF MCB‐1330803
Mangenese superoxide dismutase (MnSOD) promotes stem‐like cell phenotypes in breast cancer
Authors: He Chenxia , Hart Peter , Fricano Kristine , Vargas Micaela , Thieraud Kraig , de Abreu Andre Luelsdorf , Bonini Marcelo 
Published: June 2021

It is becoming increasingly clear that a small subpopulation of cells within tumors displaying stem cell characteristics drive tumor resistance to therapy, recurrence and metastasis. These cells are generally referred to as cancer stem cells (CSC). Reactive oxygen species (ROS) are active signaling metabolites produced in mitochondria and to a significance extent serve as determinants of cellular reprogramming to stemness. In our study we found that a primary ROS detoxifying enzyme MnSOD is dysregulated in breast cancer and that higher levels of MnSOD expression are associated with lowest survival odds in patients with tumors displaying a MnSODhigh molecular signature. In primary breast tumor cell line MCF7, overexpression of MnSOD leads to higher expression of stemness markers (Oct4, Sox2 and Nanog), increased stem cell population, and upregulation of cancer stem cell regulator hypoxia‐induced factor HIF2α transcription factor. Also, MCF7 cells which are amongst the least invasive breast cancer cell lines show significantly enhanced colony forming capacity and invasiveness ex vivo, and metastatic potential in mice. Silencing of HIF2α reversed the effect of MnSOD ectopic expression in MCF7. Altogether our results indicate that there is a MnSODhigh/HIF2α phenotype in breast cancer that displays stem‐like cell characteristics which may be involved in treatment resistance and metastatic recurrence in a subgroup of patients displaying MnSODhigh tumors.Support or Funding InformationThis research supported by the U.S. Department of Defense (ARO #61758‐LS) to M.G.B, the NCRR/NIH (S10RR027848) to M.G.B.
Regional Patterns of Pulsatility Index and Wall Shear Stress Across Cerebral Circulation of Adolescents with High Insulin Resistance
Authors: Carter Katrina J. , Kellawan J. Mikhail , Peltonen Garrett L. , Ward Aaron T. , Carrel Aaron L. , Wieben Oliver , Bendlin Barbara B. , Schrage William G. 
Published: June 2021

BackgroundInsulin resistance (IR) is associated with altered arterial stiffness, blood flow, and shear stress patterns in the peripheral circulation of middle‐aged and older diabetic and non‐diabetic hypertensive populations. Both altered blood flow and shear stress patterns may contribute to the elevated risk of cerebrovascular disease in IR populations. The aim of this study was to determine if adolescents (12–18yrs) with high IR (indexed as High Homeostatic Model Assessment of IR, HOMA‐IR) display early signs of cerebrovascular dysfunction. We hypothesized that young adolescents with a high HOMA‐IR would exhibit increased stiffness and decreased shear patterns in cerebral conduit arteries.Methods2 healthy controls (17±3) and 3 IR subjects (14±1) underwent a single 4D Flow MRI scan (scan time ~ 5min, no contrast given) to quantify cerebral blood flow (CBF), pulsatility index (PI) and wall shear stress (WSS) in extracranial and intracranial conduit arteries. 11 arteries were analyzed: middle cerebral (MCA) x2, anterior cerebral (ACA) x2, posterior cerebral (PCA) x2, vertebral (VA) x2, internal carotid (ICA) x2, and basilar. PI was calculated for each artery as [(CBFmax − CBFmin)/CBFmean]. WSS was measured by segmenting the vascular tree from PC angiograms and calculating the velocity gradient at the vessel wall using 4D flow MRI data over ~3 voxel. Due to voxel limitations, the PCA value is exploratory. Total CBF was calculated as the sum of both ICA and both VA. Significance was determined using a two‐tail Welch's t‐test.ResultsIndividuals with IR displayed higher HOMA‐IR (IR 5.3±0.2, Ctrl, 3.3±0.3, p=0.02), BMI (kg•m2; IR 28±2, Ctrl 19±4, p=0.03) and fasting insulin (μU/mL; IR 25±4, Ctrl 13±0, p=0.04), but fasting glucose was not different (mg/dL; IR 79±4, Ctrl 93±5, p=0.07). PI was not different between groups among the 11 conduit arteries. However, there was a trend for higher PI in the IR group in the left PCA and right VA. Resting WSS did not differ between Ctrl and IR among the 11 conduit arteries. Similarly, total resting CBF was not different between Ctrl and IR (mL/min; IR 811±115, Ctrl 735±79, p=0.64).ConclusionPI or WSS were similar in 11 conduit arteries of cerebral circulation in adolescent controls compared to IR. These data indicate IR does not cause measurable arterial stiffening or altered total cerebral blood flow patterns. Therefore, the pathogenic arterial characteristics observed in middle‐aged adults with IR may be linked to the duration and/or severity of IR in association with other known vascular pathological processes linked to aging.Support or Funding InformationThis research was made possible by the National Science Foundation Grant #HRD‐1500138 (UW‐Madison WiscAMP‐BD program) and UW Graduate School Pilot Funding.
The Effects of 12 Days Exposure to 4,300M Altitude on the Sympathetic Neural and Cardiovascular Responses to Head‐Up Tilt
Authors: Bradbury Karleigh Eleanor , Mitchell Katherine M , Beidleman Beth A , Fulco Charles S , Muza Stephen R , Posch Alexander M , Charkoudian Nisha 
Published: June 2021

Musclesympathetic nerve activity (MSNA) increases with acute and chronic altitude exposure. However, the effects of altitude exposure on the neural and hemodynamic responses to orthostasis are not clear. The purpose of the current study was to evaluate the effects of altitude exposure (12 days; 4,300 m, Pikes Peak, CO) on MSNA, heart rate (HR) and systolic (SBP) and diastolic (DBP) blood pressure during supine rest and 30° and 45°head up tilt (HUT). We hypothesized that: (1) MSNA would be elevated upon return to sea level (SL, 50 m) from Pikes Peak and (2) increased resting MSNA would be associated with decreased responses to HUT due to a potential ‘ceiling effect’. Supine MSNA, HR, SBP and DBP were measured in 9 healthy subjects (7 M, 2 F; 24 ± 8 years)prior to‐, and within 24 hr of return from altitude. MSNA was measured via peroneal microneurography. Subjects rested supine for 10–15 min to collect baseline data, then were tilted to 30° HUT for 2–3min, followed by 45° HUT for 2–3 min. Supine MSNA was increased within 24 hr return from altitude (27 ± 5 vs 17 ±6 bursts/min [SL], p < 0.05, ANOVA). MSNA at 30° HUT was higher within 24 hr return from altitude (36 ± 8bursts/min vs 25 ± 7 [SL], p< 0.05). MSNA tended to be higher at 45° HUT (39 ± 8 bursts/min vs 30 ± 9 [SL], p = 0.07). There was no difference in the extent of change in MSNA from supine to 30° HUT orsupine to 45° HUT between SL and post‐altitude (p > 0.05). There were no changes in HR, SBP or DBP supine, 30° HUT, and 45° HUT post‐Pikes Peak compared to sea level(p > 0.05 for all). Our data suggest that 12 days of altitude exposure increases resting (supine) MSNA but does not alter the ability of sympathetic vasoconstrictor nerves to increase activity in response to a baroreflex stimulus (HUT).Support or Funding InformationFunded by USAMRMC; author views not official US Army or DOD policy.
Peptidergic Modulation in the Lobster Cardiac Neuromuscular System: A Transcriptomic Analysis of Peptides and Peptide Receptors in Cardiac Ganglion and Muscle
Authors: Gandler Helen , Stanhope Meredith , Shea Devlin , Christie Andrew , Yu Andy , LaMeyer Tess , Roncalli Vittoria , Cieslak Matthew , Dickinson Patsy 
Published: June 2021

Central pattern generator (CPG)‐effector systems can produce flexible rhythmic motor output via modulation by both intrinsically‐ and extrinsically‐derived neuropeptides. In the lobster, Homarus americanus, the cardiac neuromuscular system, which consists of the cardiac ganglion (CG) and cardiac muscle (CM), controls the rhythmic motor output of the heart. This is a well‐studied, but simple, CPG‐effector system that has been used extensively for investigating peptidergic control of rhythmic behavior. Here, transcriptomes were generated for the two components that comprise the cardiac neuromuscular system, the cardiac ganglion (CG) and cardiac muscle (CM). Transcripts encoding precursor proteins for approximately ten peptide families, including allatostatin‐C (AST‐C), diuretic hormone 31 (DH31), diuretic hormone 44, myosuppressin, and proctolin, were identified from the CG transcriptome, suggesting that these peptide groups may be produced by neurons in the CG. Transcripts encoding receptors for many of the peptides identified from the CG, including those for all four of the above‐mentioned peptide families, were also identified from the CG and/or CM transcriptomes, suggesting that these peptides serve as intrinsic modulators of the cardiac neuromuscular system. To investigate hormonal modulation in the cardiac neuromuscular system, the transcriptomes were mined for the receptors of peptides known to be present in the sinus gland and/or pericardial organs, two neuroendocrine organs. Receptors for seven peptide families were identified, with some receptors restricted either to the CG (crustacean cardioactive peptide, red pigment concentrating hormone, and tachykinin‐related peptide) or CM (pigment dispersing hormone), and others found in both tissues (AST‐C, myosuppressin, and proctolin). These data suggest that some peptides may have different sites of action within the cardiac neuromuscular system. Immunohistochemistry confirmed that DH31 is produced by the motor neurons of the CG, and suggested that AST‐C is present in the CG. Immunohistochemical confirmation of the other putative intrinsic CG modulators is ongoing.Support or Funding InformationNSF (IOS‐1353023, IOS‐1354567, OCE‐1459235), NIH (8P20GM103423‐12), Cades Fdn., University of Hawaii at Manoa's Undergrad Res. Opp. Prog., APS Undergrad Res. Fellowship, Doherty Fdn./Bowdoin College
Water Restrictions and Macronutrient Level Intake of Locust
Authors: Diaz Mildred Isabel , Harrison Jon , Cease Arianne 
Published: June 2021

Locust are grasshoppers that tend to migrate in swarms that can cause major damage to agriculture. Chortoicetes terminifera are locust native to Australian deserts, where they can potentially experience water restrictions. I hypothesized that water restriction would slow growth; and that high‐protein diets will be more deleterious under water‐restricted conditions because nitrogenous wastes require water to eliminate. Locusts were collected on the day they molted into the fifth (final) instar, weighed and placed in an individual plastic cage. Locusts received ad lib quantities of two different dry, granular diets: 35% protein:7% carbohydrate or 14% protein:28% carbohydrate. Locusts either had unlimited water or had ad lib access to water during every third day. All locust were given water on the day they molted for 24 hours. Then the locust on the restricted water treatment had no water for two days, followed by 24 hours with water, then 48 hours without water, continuing this pattern until the locust molted. After the locusts molted into adults, which took approximately 10 – 15 days, their final body mass (wet and dry) was recorded. Consumption rate was calculated by the loss in mass of the food pile over the entire instar, and their growth rates from the change in wet mass and development time (measured with a precision of ±1 day). Water restriction did not affect body water content or many measures of growth and size, suggesting this was a mild stress. Sexes differed in their responses, with water restriction reducing growth in males but not females. However, size and growth of females were much more affected by the diet than males; with the high‐protein diet strongly lowering body mass, food consumption and growth rate in females. Males consumed less of the high‐protein diet, but their adult mass and growth rate were unaffected by diet. High protein diets increased body water content for both sexes, possibly because high carbohydrate diets were associated with an increase in fat storage. There were few interactions between diet and water restriction, and contrary to our hypothesis, no consistent evidence that high‐protein diets were more deleterious under water restricted conditions. Future studies should examine the sex‐specific growth and metabolic responses to dietary protein:carbohydrate content. This research project was made possible thanks supported by the American Physiological Society and a grant from the National Science Foundation Integrative Organismal Systems IOS‐1238831 as well as the DEB 1313696, and CHE 1313958.Support or Funding InformationThis research project was made possible thanks supported by the American Physiological Society and a grant from the National Science Foundation Integrative Organismal Systems IOS‐1238831 as well as the DEB 1313696 and CHE 1313958.
> π* Interaction in Designed Peptides
Authors: Wenzell Nicole , Ganguly Himal , Pandey Anil , Yap Glenn P.A , Zondlo Neal J 
Published: June 2021

An n‐‐>π* interaction is a non‐covalent interaction that orders two consecutive residues in a peptide/protein by delocalizing the lone pair of electrons from the oxygen of a donor carbonyl to the antibonding orbital of an acceptor carbonyl carbon. This interaction gives insight into the inherent biases that drive protein folding, as it stabilizes secondary structures such as α‐helices and polyproline helices.We synthesized a series of hydroxyproline‐based peptides with variable N‐terminal substituents, modulating the electron‐donating capabilities on the donor carbonyl. By changing the electronics of each donor carbonyl we can tune the strength of this n‐‐>π* interaction and explore its structural implications. The n‐‐>π* interaction stabilizes the trans conformation of a peptide bond. Because proline can readily populate both trans and cis conformations, the ratio of the two species (Ktrans/cis) indicates the strength of the n‐‐>π* interaction.The series of derivatives synthesized were selected to compare the electron‐donating capabilities of their donor carbonyl to its n‐‐>π* interaction strength. The derivatives synthesized for analysis were, X‐Hyp(4‐NO2Bz)‐OMe where X = Boc, pivaloyl, formyl, acetyl, propionyl, monochloroacetyl, monofluoroacetyl, dichloroacetyl, difluoroacetyl, trichloroacetyl and trifluoroacetyl. These derivatives provide a range of electronic properties to be analyzed for the strength of the nàπ* interaction in each compound.Combined analysis via 1H and 13C NMR and X‐ray crystallography reveals the characteristics of the n‐‐>π* interaction. Cis and trans species can be differentiated by 1H NMR, providing the Ktrans/cis for each derivative. Electron donation involved in the n‐‐>π* interaction is seen via the carbonyl chemical shifts using 13C NMR. The chemical shift of the acceptor carbonyl moves downfield with stronger electron‐donating substituents, while carbonyls uninvolved in the interaction remain constant. X‐ray crystallography reveals the distances and angles of the n‐‐>π* interaction, including torsion angles seen in protein secondary structures. Specifically, the propionyl donor carbonyl results in the crystallographic observation of an α‐helical conformation, inducing compact torsion angles (φ = −58.6° and ψ = −37.8°), without the presence of a hydrogen bond. An electron rich donor results in the strongest interaction. Our comparison of this series of donor‐acceptor carbonyl pairs reveals the energetics and geometry of the n‐‐>π* interaction, granting new and unique insights into the problem of protein folding.Support or Funding InformationI'd like to extend my gratitude towards David Plastino and the NSF for providing funding for this research.
How the Loss of a Single Hydroxyl Group Affects the Proteolytic Activity of the Model Serine Protease, Trypsin
Authors: Huang Jennifer , Batt Anna R. , St. Germain Commodore P. , Baird Teaster 
Published: June 2021

Trypsin is used as a model for the study of serine proteases, for its fold is commonly observed in this family of enzymes. The overall aim of this study is to discern whether the Y39F trypsin variant will act on a macromolecular substrate similar to the way it interacts with macromolecular inhibitors, specifically focusing on the S prime (S') side. In wild‐type trypsin, the hydroxyl group in tyrosine at position 39 serves to stabilize the interaction with macromolecular inhibitors via the formation of hydrogen bonds at the P prime (P') subsites. A Y39F substitution was made to reduce the affinity between the enzyme variant and inhibitor. A phenylalanine was used in place of the tyrosine because the two amino acid residues are chemically similar with the exception of the hydroxyl functional group missing from the phenylalanine. The absence of the hydroxyl functional group serves to prevent the formation of hydrogen bonds between macromolecular substrates that interact with the S' site of the enzyme, presumably weakening of the enzyme‐inhibitor interaction. However, previous research from our group demonstrated that the Y39F trypsin variant was more sensitive to inhibition from both bovine pancreatic trypsin inhibitor (BPTI) and ecotin compared to wild‐type trypsin. Molecular modeling suggests that the tighter binding is a consequence of the formation of a hydrogen bond between the P2′ site and the histidine side chain at position 40 not seen in wild type trypsin. The presence of the newly formed hydrogen bond in the Y39F trypsin variant helps stabilize the enzyme‐inhibitor complex. Still, Y39F trypsin retained similar catalytic activity against N‐α‐benzyloxycarbonyl‐glycylprolylarginine p‐nitroanilide (Z‐GPR‐pNA). However, Z‐GPR‐pNA physically cannot interact with the modified S' subsites as the macromolecular inhibitors, and likely macromolecular substrates, do. Therefore, the activity observed with Z‐GPR‐pNA may not accurately reflect the activity of the Y39F variant towards macromolecular substrates. In this study, we used sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) and gel imaging to monitor and compare the progression of macromolecular substrate hydrolysis of Y39F and wild‐type trypsin. Based on the observations made with BPTI and ecotin, we would expect that the Y39F variant would bind more tightly to a macromolecular substrate as well, likely increasing the efficiency of cleavage relative to wild‐type.Support or Funding InformationNSF Award MCB‐0643988‐02