bluuebunny/crossref_metadata_2025_split huggingface dataset:
NIRS‐derived Microvascular Oxygen Saturation Kinetics Related to Skeletal Muscle Metabolic Rate
Authors: Margo Amadea C. , Townsend Dana K. , Hunt Brian E. , Barstow Thomas J. 
Published: April 2020

IntroductionSkeletal muscle tissue oxygen hemoglobin/myoglobin saturation (STO2) measured during post occlusive reactive hyperemia (PORH) provides a kinetic parameter (STO2 upslope (%/time)) that has increasingly been used as a measure of microvascular responsiveness. The magnitude of the oxygen saturation prior to cuff release (STO2 min) often correlates to STO2 upslope but the physiological variable associated with variability in STO2 min is most likely muscle metabolic rate (MR). This physiologic variable likely influences the rate of reperfusion after cuff release. The purpose of this study, therefore, was to isolate variables contributing to differences in STO2 upslope through their influence on STO2 min. Our hypothesis was that MR would significantly affect STO2 upslope.MethodsThe anterior antebrachium of twenty‐two (11 male, 11 female), 18–26 years, normoglycemic subjects was monitored continuously by near infrared spectroscopy during three upper limb PORH tests. Tissue oxygenation variables were determined prior to, during the cuff and for 2.5 min. post‐cuff release. MR was calculated in ml O2/100 g lean tissue/min and used both corrected and uncorrected for ATT (MRC). Body fat and abdominal adiposity (%) were quantified by dual energy‐ray absorptiometry. Forearm adipose tissue thickness (ATT) (3.32 + 1.43 mm, range 2.8–6.7 mm) was measured by ultrasound.ResultsSTO2 min and STO2 upslope were significantly negatively correlated (r=−0.47, P= 0.03) and both were significantly negatively correlated with MR (r = −0.75, P = <0.001 and r = −0.52, P = 0.01, respectively). In a multiple, forward step‐wise regression analysis with a dependent variable of STO2 upslope and independent variables of ATT, MR or MRC, STO2min, and total body fat, only ATT entered the equation (R squared 0.334, P= 0.006); no other variable statistically added any independent predictive power to the regression equation.ConclusionsTo our knowledge, this is the first study to assess the effects of MR on NIRS STO2 upslope. In contrast to our hypothesis, MR did not affect STO2 upslope but ATT did. This finding suggests that ATT must be taken into account when assuming differences in STO2 upslope reflect differences in microvascular reactivity even in largely lean subjects.Support or Funding InformationAmerican Heart Association, Grant/Award Number: 0151183ZWheaton College Alumni Summer Research Support
A Novel Model of Long‐term Human Microvascular Endothelial Cell Serum Starvation
Authors: Rossiter Jackie Lee , Yosten Gina , Kolar Grant 
Published: April 2020

Microvascular endothelial cell injury and progressive loss of microvasculature in the dermis, kidney, retina and perineural beds is caused by hyper‐and hypoglycemic insults in individuals with Diabetes mellitus (DM). The consequence of microvascular injuries occurring over years to decades is the onset of DM‐associated co‐morbidities such as delayed wound healing, renal failure, vision loss and peripheral neuropathy. The Diabetes Control and Complications Trial noted a correlation between baseline endogenous C‐peptide serum levels and the delay in onset of DM‐associated co‐morbidities. In immortalized human microvascular endothelial cells (HMEC) and primary human dermal microvascular endothelial cells treatment with 1.5nM C‐peptide and 0.5nM insulin prevented hyperglycemia‐induced oxidative injury. In studies of these cells using immunofluorescence to track C‐peptide and the C‐peptide receptor, G‐protein coupled receptor 146 (GPR146), endothelial cells repeatedly demonstrated cytosolic stores of C‐peptide. Fetal bovine serum, a component of almost all cell culture growth media was determined to have high concentrations of C‐peptide. The aim of this study was to develop a model of long term endothelial serum starvation that would result in depleted internal stores of C‐peptide, but would prevent endothelial cells transformation to smooth muscle cells or fibroblasts, as endothelial progenitor cells are capable of differentiating into one of these three cell types. We hypothesized that cytosolic C‐peptide would reduce over time with serum starvation. To test this hypothesis, HMEC were incubated for up to two months in MCDB13 media supplemented with human epidermal growth factor, hydrocortisone, vascular endothelial growth factor, basic fibroblast growth factor, insulin‐like growth factor‐1, ascorbic acid, and L‐glutamine. Serum starved HMEC were harvested at various time points and stained for C‐peptide (MAB80561 R&D Systems clone 915612) and DAPI or lysed with lysis buffer with 2‐mercaptoethanol followed by RNA isolation, cDNA preparation and RT‐PCR evaluation of targets. Cytosolic C‐peptide fluorescent signal diminished over time in a linear manner but was never completely abolished. HMEC serum starved for 30 days retained endothelial markers CD31, CD34, VEGFR2, had no change in smooth muscle markers Smoothelin, or Smooth muscle actin, and similarly, had no change in expression Vimentin a fibroblast marker relative to un‐serum starved HMEC controls as determined by RT‐PCR. The ability to serum starve HMEC long‐term and substantially reduce internal C‐peptide stores has the potential to enhance research to elucidate the pathways employed by C‐peptide in the prevention of hyperglycemia‐induced microvascular injury.Support or Funding InformationNIDDK
SAP97 mediates local control of cAMP/PKA gradient to regulate L‐type calcium channels in hearts
Authors: Zhao Meimi , Wang Ying , Shi Qian , Xu Bing , Xiang Yang Kevin 
Published: April 2020

RationaleHeart failure as one of the leading causes of morbidity worldwide is hallmarked by dysregulated myocardial calcium (Ca2+) and cardiomyocyte apoptosis. There exists an urgent unmet need of developing novel therapies for preventing and reversing HF progression by correcting Ca2+ dysregulation and inhibiting apoptosis. However, the mechanisms underlying Ca2+ regulation in physiological and pathological conditions remain incompletely elucidated.ObjectiveTo identify how a synaptic associated protein 97 (SAP97) controls cardiac intracellular Ca2+ in both physiological and HF development.Methods and ResultsWe used genetic deletion (cardiomyocyte specific SAP97 knock out mice, SAP97‐cKO) to determine the essential role of SAP97 in regulating the Ca2+ channel activity and how this contributes to the heart failure process. Proximity ligation assay (PLA) and confocal imaging technology were applied to identify a novel SAP97/protein Kinase A (PKA)/ L‐type calcium channel (LTCC) protein machinery complex. We use fluorescence resonance energy transfer (FRET) and living cell imaging to analyze the dynamic spatial changes of Ca2+ homeostasis under the sympathetic adrenergic control of SAP97/LTCC complex. Our study found that a SAP97 binds LTCC and modulates PKA‐dependent LTCC activation via scaffolding PKA and phosphodiesterase 4D8 (PDE4D8) in cardiomyocyte. Disruption of this complex impaired the negative feedback control of cAMP/PKA by PDE4D8, therefore augments PKA‐dependent LTCC activation and promotes Ca2+ dysregulation. Moreover, genetic deletion of SAP97 enhances cAMP/PKA activity and induces Ca2+ dysregulation, which promotes cardiomyocyte apoptosis and HF development in mice.ConclusionSAP97 mediated local control of cAMP/PKA gradients regulates LTCC and Ca2+ homeostasis in failing heart, therefore offer a novel SAP97/PKA/Ca2+ signaling axis as a therapeutic target for heart failure prevention and treatment.Support or Funding InformationThis study was supported by NIH grants HL113413 and HL147264 and VA Merit grant 01BX002900 to Y.K.X.
Protein‐DNA Interactomes of NKX2‐5 Mutants Identified in Congenital Heart Defects
Authors: Carrasquillo-Dones Emmanuel Antonio , César Brenda , Rodriguez-Martinez Jose Arcadio 
Published: April 2020

Congenital Heart Defects (CHDs) are one of the most common birth defects, with over 100,000 new reported cases each year. CHDs are characterized by malformations in the heart’s chambers, walls and great vessels, sometimes leading to embryonic death. NKX2‐5 is cardiac transcription factors (cardiac TFs) that play a critical role in developmental stages and physiological process of the heart. Transcription factors regulate gene expression via sequence‐specific interactions with DNA. Genetic analyses of CHD patients have identified various non‐synonymous mutations within the DNA‐binding domain (DBD) of NKX2‐5. We hypothesize that non‐synonymous mutations in NKX2‐5’s DBD will alter their DNA‐binding properties ultimately affecting transcriptional pathways necessary for proper heart development. To address this hypothesis, we want to study how the cardiac TFs DNA‐protein interactomes are affected by non‐synonymous mutations found in CHD patients. We have successfully cloned, over‐expressed and purified the homeodomain (HD) DBD of NKX2‐5. Functional analysis protocols using Electrophoretic Mobility Shift Assay (EMSA) confirms protein binding to its DNA binding sites. Additionally, we generated 7 non‐synonymous NKX2‐5 CHD mutants (A148E, E154G, R161P, L171R, T178M, Q181H, R189P) via site directed mutagenesis. Comprehensive protein‐DNA interactomes of NKX2‐5 and its mutants will be determined by Systematic Evolution of Ligands and Exponential Enrichment (SELEX‐seq). Bioinformatics tools will be used predict changes in DNA‐binding preferences and putative gene targets between wild‐type and mutant TFs.Support or Funding InformationThis research was supported: NIH grant award SC1GM127231 Research Initiative for Scientific Enhancement (RISE) Grant #5R25GM061151‐18
Influence of Exercise Modality on the Cerebrovascular Response to Physiological Stressors
Authors: Corkery Adam T. , Pearson Andrew G. , Miller Kathleen B. , Howery Anna J. , Barnes Jill N. 
Published: April 2020

BackgroundHabitual exercise has previously been shown to alter the cerebrovascular response to hypercapnia. Similar to hypercapnia, increases in the brain’s metabolic activity result in local augmentation of cerebral blood flow; however, the mechanisms governing the cerebrovascular response to these two stimuli likely differ. Although, previous studies have examined the influence of aerobic exercise on the cerebrovascular response to hypercapnia, little is known about the influence of habitual resistance training on cerebrovascular function. Therefore, the purpose of this study was to evaluate the cerebrovascular response to both hypercapnia and a metabolic stimulus (cognitive challenge) in resistance trained (RT), aerobic trained (AT), and untrained (UT) adults.MethodsWe recruited 13 RT (women: n = 2, age: 24 ± 4 y), 12 AT (women: n = 2, age: 28 ± 6 y), and 13 UT (women: n = 2, age: 27 ± 5 y) healthy young adults. Middle cerebral artery velocity (MCAv), beat‐to‐beat mean arterial blood pressure (MAP) and end‐tidal carbon dioxide (ETCO2) were continuously monitored during hypercapnia and a Stroop Color and Word Test. Cerebrovascular conductance index (CVCi) was calculated as MCAv/MAP. Reactivity to hypercapnia was calculated as the slope of the relationship between each variable of interest (MCAv or CVCi) and ETCO2. Responses to the Stroop test were calculated as the absolute change from baseline to the 3‐beat peak of each variable during the test.ResultsThere were no significant differences in MCAv reactivity and CVCi reactivity to hypercapnia between groups. Despite all groups having a similar change in MAP and ETCO2 during the Stroop test, RT individuals had a greater increase in MCAv (RT: 18.1 ± 1.9 cm/s, AT: 9.7 ± 1.5 cm/s, UT: 15.7 ± 2.0 cm/s; AT vs. RT p < 0.01; AT vs. UT p = 0.07) and CVCi (RT: 0.15 ± 0.02 cm/s/mmHg, AT: 0.08 ± 0.02 cm/s/mmHg, UT: 0.12 ± 0.02 cm/s/mmHg; AT vs. RT p = 0.05; AT vs. UT p = 0.28) compared with AT individuals during the Stroop test. While there was a positive association between the MCAv response to hypercapnia and the MCAv response to the Stroop test in AT individuals (r = 0.67, p < 0.05), and a trend for association in UT individuals (r = 0.49, p = 0.09), there was no relationship between the two variables in RT individuals (r = 0.18, p = 0.56).ConclusionWhile exercise modality did not influence the cerebrovascular response to hypercapnia, it did influence the response to a metabolic stimulus, such that RT individuals had a greater MCAv and CVCi response to a cognitive challenge, compared with AT individuals. Further, exercise modality may influence the mechanisms by which the cerebrovasculature of young adults responds to physiological stimuli.Support or Funding InformationSupported by National Institute of Health grant HL118154
In vivo metabolomic and lipidomic response of healthy humans to intravenous lipopolysaccharide challenge
Authors: Bresette William , Skulas-Ray Ann Christine , Tontsch Chandra , Tomich Tatiana , Hudson Oneida , Richter Chesney K. , Kris-Etherton Penny M. , Jensen Gordon L. , Chilton Floyd 
Published: April 2020

IntroductionAcute inflammation is a complex protective response to injury or infection. However, systemic hyperinflammatory states can lead to septic shock. Lipopolysaccharide (LPS) is a component of gram‐negative bacteria that is widely used for inducing inflammatory responses in animal models. However, many of the critical molecular networks involved in the LPS response in humans remain largely unknown.ObjectiveTo better characterize the molecular underpinnings of acute inflammation in humans through real‐time biochemical and network appraisals of in vivo challenge with LPS.MethodsHealthy men were intravenously injected with 0.6 ng/kg LPS at Pennsylvania State University. Plasma markers of inflammation (IL‐6, TNFα, and CRP) were measured prior to and 1, 2, 4, 8, 24, and 72 h post injection. Untargeted metabolomic and lipidomic profiling using liquid chromatography tandem mass spectrometry was conducted on the plasma from 10 men. Deuterated internal standards (SPLASH, Avanti Polar Lipids) were added to plasma to facilitate semi‐quantitative analysis of individual lipid molecular species. Statistics were performed in R (version 1.1.463) and Microsoft Excel (version 16.30).ResultsOf the 1847 metabolites reliably detected, 265 remained significant (FDR‐adjusted p < 0.05) after analysis. Of these metabolites, 197 increased, 51 decreased, and 17 both increased and decreased (depending on the point in the time course). Both metabolomics and lipidomics revealed that molecular species of lipid classes including phospholipids (PL), lyso‐PLs, sphingolipids (SL), diglycerides (DG), and triglycerides (TG) had largest number of metabolites altered after LPS challenge. Notably, levels of 50 lyso‐PLs including lyso‐phosphatidylcholine (PC) and lyso‐phosphatidylethanolamine (PE) molecular species were increased in plasma. Additionally, there were significant elevations in certain PL molecular species representing PC, PE, phosphatidylserine, and phosphatidylinositol. Levels of 29 molecular species of SL increased with the majority representing sphingomyelin and ceramide classes. Neutral lipids including DG and TG were also markedly elevated. Pathway analyses highlighted glycerophospholipid metabolism (p < 0.0001) and sphingolipid metabolism (p < 0.001) as highly significant. These data also suggest the activation of multiple lipases including phospholipase A2, phospholipase C and phospholipase D play a critical role in the inflammatory response induced by LPS.DiscussionIntravenous LPS injection profoundly alters lipid metabolism in healthy adult men. These data may facilitate the identification of biochemical lipid networks and the development of biomarkers associated with inflammatory health/disease status.Support or Funding InformationFunding source: NIH R01 AT008621
Pulmonary arterial vasoreactivity changes due to the birth transition and the influence of high altitude gestation in lambs
Authors: Murray Samuel , Hanson Shawn F.L. , Blood Arlin B. , Wilson Sean M. 
Published: April 2020

Gestation and birth at high altitude is a risk factor in the development of pulmonary hypertension (PH) in the newborn, which afflicts approximately 6 in every 1000 term births. Prior to birth the pulmonary vasculature has high resistance and low flow, however during the transition at birth the resistance drops rapidly allowing for increases in flow. Previous evidence illustrates that high altitude gestation hinders this transition process, which leads to PH. To begin to understand this process in more depth and the etiology associated with the development of PH with birth at high altitude we tested the hypothesis that high altitude gestation would increase arterial reactivity and decrease vasodilatory capacity in lambs going through birth transition. This was examined in wire myography studies performed on pulmonary arteries isolated from near‐term (139 to 141 days gestation, term = 145) fetal lambs that gestated at high altitude (3801 m) for 110+ days or at low altitude (700 m). Ewes were anesthetized with isoflurane and lambs were delivered by C‐section and immediately sacrificed or underwent experimentally‐induced birth transition. Birth‐transition lambs were instrumented with an arterial catheter and endotracheal tube and delivered via C‐section, anesthetized with ketamine (1 mg/kg boluses every hour), and mechanically ventilated with an FiO2 of 30% for three hours. Arterial PO2 and PCO2 were maintained within normal newborn ranges by adjusting tidal volumes and ventilator rate. Lungs were harvested from near term and birth transition lambs and arteries isolated for wire myography. In the wire myography studies evaluations were made of electromechanical coupling by contracting arteries with 125 mM KCl (High K), pharmacomechanical coupling by exposing arteries to additive concentrations of serotonin (5‐HT), and vasodilatory capacity with S‐Nitroglutathione (gSNO), a biologically relevant source of NO. High altitude gestation reduced arterial reactivity to High K and 5‐HT in near term fetuses while birth transition reduced arterial reactivity in low altitude but not high altitude animals. The potency for 5‐HT was diminished in animals that went through birth transition. Dilatory capacity to gSNO was impaired by high altitude gestation but unaffected by the birth transition. These data suggest that the birth transition preferentially reduces constrictor pathways and that dilatory pathways are well developed at the time of birth. High altitude gestation then reduces both contractile as well as dilatory capacities, paralleling other data suggesting high altitude gestation causes cellular immaturity.Support or Funding InformationSupported in part by NIH grant HD083132 (ABB), HD098477 (SMW)
Co‐modulation of the Na+/K+ pump and hyperpolarization‐activated currents as a mechanism for robust neuromodulation
Authors: Ellingson Parker , Barnett William Halbert , Vargas Alex , Kueh Daniel , Calabrese Ronald , Cymbalyuk Gennady 
Published: April 2020

Specialized oscillatory circuits, central pattern generators (CPGs), control rhythmic motor behaviors such as locomotion and breathing. To accommodate a motor pattern to environmental changes and behavioral goals, neuromodulators adjust the dynamics of CPGs by orchestrating changes in various ionic currents in a wide range of their biophysical parameters to expand temporal characteristics of the functional pattern. Recent studies provide evidence that the Na+/K+ pump contributes to the dynamics of CPGs and is controlled by neuromodulation
[1–
4]. In the leech heartbeat CPG, the neuropeptide myomodulin reduces the period of bursting activity by increasing the hyperpolarization‐activated (h)‐current and decreasing the Na+/K+ pump current
[4]. The application of myomodulin reduces the period of oscillatory activity by 17%. Application of Cs+, which is an h‐current blocker, increases the period of bursting by 24% relative to control. The application of myomodulin along with Cs+ decreases the period by 12% relative to treatment with Cs+
[4]. Here we investigate how the period of a bursting can be controlled in a wide range while functional bursting is maintained with a focus on the role of the Na+/K+ pump. We also investigate the risk associated with multistability in neuronal dynamics.We optimized a model of the leech heart interneuron (HN), which includes the Na+/K+ pump current and intracellular Na+ dynamics
[1] and investigated the activity regimes of pairs of mutually inhibitory coupled HNs forming half‐center oscillators (HCOs). HCOs form the kernel of the leech heartbeat CPG. We investigated eight model variants representing combinations of three experimental treatments: the blockade of chemical synapses representing the application of bicuculline, the blockade of h‐current representing the application of Cs+, and the enhancement of the h‐current and inhibition of the Na+/K+ pump current representing the application of myomodulin. The model captures the qualitative trends in change of cycle period observed in experiments with myomodulin and Cs+. We found ranges of parameters where neurons showed functional bursting. The coordinated changes of maximal conductance of h‐current (Gh) and maximal pump activity (IPumpMax) increases the range of period of functional bursting as well as the range of parameters Gh and IPumpMax. We hypothesize that myomodulin co‐modulates h‐ and pump currents to expand the domain of the functional activity.Support or Funding InformationSupported by NINDS 1 R01 NS085006 to RLC and 1 R21 NS111355 to RLC and GSC.