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https://www.readbyqxmd.com/read/29770687/spatial-associations-and-chemical-composition-of-organic-carbon-sequestered-in-fe-ca-and-organic-carbon-ternary-systems
#1
Tyler Sowers, Dinesh Adhikari, Jian Wang, Yu Yang, Donald L Sparks
Organo-mineral associations of organic carbon (OC) with iron (Fe) oxides play a major role in environmental OC sequestration, a process crucial to mitigating climate change. Calcium has been found to have high co-association with OC in soils containing high Fe content, increase OC sorption extent to poorly-crystalline Fe oxides, and has long been suspected to form bridging complexes with Fe and OC. Due to the growing realization that Ca may be an important component of C cycling, we launched a scanning transmission X-ray microscopy (STXM) investigation, paired with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, in order to spatially resolve Fe, Ca, and OC relationships and probe the effect of Ca on sorbed OC speciation...
May 17, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29668881/hyperactive-ryanodine-receptors-in-human-heart-failure-and-ischemic-cardiomyopathy-reside-outside-of-couplons
#2
Eef Dries, Demetrio J Santiago, Guillaume Gilbert, Ilse Lenaerts, Bert Vandenberk, Chandan K Nagaraju, Daniel M Johnson, Patricia Holemans, H Llewelyn Roderick, Niall Macquaide, Piet Claus, Karin R Sipido
Aims: In ventricular myocytes from humans and large mammals, the transverse and axial tubular system (TATS) network is less extensive than in rodents with consequently a greater proportion of ryanodine receptors (RyRs) not coupled to this membrane system. TATS remodeling in heart failure (HF) and after myocardial infarction (MI) increases the fraction of non-coupled RyR. Here we investigate whether this remodeling alters the activity of coupled and non-coupled RyR sub-populations through changes in local signaling...
April 14, 2018: Cardiovascular Research
https://www.readbyqxmd.com/read/29459735/structural-heterogeneity-of-the-rat-pulmonary-vein-myocardium-consequences-on-intracellular-calcium-dynamics-and-arrhythmogenic-potential
#3
C Pasqualin, A Yu, C O Malécot, F Gannier, C Cognard, D Godin-Ribuot, J Morand, P Bredeloux, V Maupoil
Mechanisms underlying ectopic activity in the pulmonary vein (PV) which triggers paroxysmal atrial fibrillation are unknown. Although several studies have suggested that calcium signalling might be involved in these arrhythmias, little is known about calcium cycling in PV cardiomyocytes (CM). We found that individual PV CM showed a wide range of transverse tubular incidence and organization, going from their virtual absence, as described in atrial CM, to well transversally organised tubular systems, like in ventricular CM...
February 19, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29397451/the-synergistic-effect-of-calcium-on-organic-carbon-sequestration-to-ferrihydrite
#4
Tyler D Sowers, Jason W Stuckey, Donald L Sparks
Sequestration of organic carbon (OC) in environmental systems is critical to mitigating climate change. Organo-mineral associations, especially those with iron (Fe) oxides, drive the chemistry of OC sequestration and stability in soils. Short-range-ordered Fe oxides, such as ferrihydrite, demonstrate a high affinity for OC in binary systems. Calcium commonly co-associates with OC and Fe oxides in soils, though the bonding mechanism (e.g., cation bridging) and implications of the co-association for OC sequestration remain unresolved...
February 3, 2018: Geochemical Transactions
https://www.readbyqxmd.com/read/29289652/cellular-mechanisms-of-metabolic-syndrome-related-atrial-decompensation-in-a-rat-model-of-hfpef
#5
Felix Hohendanner, David Bode, Uwe Primessnig, Tim Guthof, Rafael Doerr, Sarah Jeuthe, Sophie Reimers, Kun Zhang, Doris Bach, Paulina Wakula, Burkert M Pieske, Frank R Heinzel
Heart failure (HF) with preserved ejection fraction (HFpEF) is present in about 50% of HF patients. Atrial remodeling is common in HFpEF and associated with increased mortality. We postulate that atrial remodeling is associated with atrial dysfunction in vivo related to alterations in cardiomyocyte Calcium (Ca) signaling and remodeling. We examined atrial function in vivo and Ca transients (CaT) (Fluo4-AM, field stim) in atrial cardiomyocytes of ZSF-1 rats without (Ln; lean hypertensive) and with metabolic syndrome (Ob; obese, hypertensive, diabetic) and HFpEF...
February 2018: Journal of Molecular and Cellular Cardiology
https://www.readbyqxmd.com/read/29167165/long-term-high-altitude-hypoxia-influences-pulmonary-arterial-l-type-calcium-channel-mediated-ca-2-signals-and-contraction-in-fetal-and-adult-sheep
#6
Christine P Shen, Monica Romero, Alexander Brunelle, Craig Wolfe, Abigail Dobyns, Michael Francis, Mark S Taylor, Jose L Puglisi, Lawrence D Longo, Lubo Zhang, Christopher G Wilson, Sean M Wilson
Long-term hypoxia (LTH) has a profound effect on pulmonary arterial vasoconstriction in the fetus and adult. Dysregulation in Ca2+ signaling is important during the development of LTH-induced pulmonary hypertension. In the present study, we tested the hypothesis that L-type Ca2+ channels (CaL ), which are voltage dependent and found in smooth, skeletal, and cardiac muscle, are important in the adaptation of pulmonary arterial contractions in postnatal maturation and in response to LTH. Pulmonary arteries were isolated from fetal or adult sheep maintained at low or high altitude (3,801 m) for >100 days...
March 1, 2018: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/29058499/direct-fluorescent-labeling-for-efficient-biological-assessment-of-inhalable-particles
#7
Bijay Kumar Poudel, Jae Hong Park, Jiseok Lim, Jeong Hoon Byeon
Labeling of aerosol particles with a radioactive, magnetic, or optical tracer has been employed to confirm particle localization in cell compartments, which has provided useful evidence for correlating toxic effects of inhaled particles. However, labeling requires several physicochemical steps to identify functionalities of the inner or outer surfaces of particles, and moreover, these steps can cause changes in size, surface charge, and bioactivity of the particles, resulting in misinterpretations regarding their toxic effects...
October 23, 2017: Nanotoxicology
https://www.readbyqxmd.com/read/29045723/acute-administration-of-tumour-necrosis-factor-%C3%AE-induces-spontaneous-calcium-release-via-the-reactive-oxygen-species-pathway-in-atrial-myocytes
#8
Song Zuo, Lin-Ling Li, Yan-Fei Ruan, Le Jiang, Xin Li, Song-Nan Li, Song-Nan Wen, Rong Bai, Nian Liu, Xin Du, Jian-Zeng Dong, Chang-Sheng Ma
Aims: The arrhythmogenic mechanisms of atrial fibrillation (AF) that are induced by acute inflammation, such as postoperative AF, are not well understood. We investigated the acute effects of tumour necrosis factor-α (TNF-α) that mimic acute inflammation on Ca2+ handling in isolated atrial myocytes and its underlying mechanisms. Methods and results: Cytosol Ca2+ handling and mitochondrial reactive oxygen species (ROS) production were studied in freshly isolated atrial myocytes of wild-type mice that were exposed to TNF-α (0...
October 17, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/29030236/accentuated-vagal-antagonism-paradoxically-increases-ryanodine-receptor-calcium-leak-in-long-term-exercised-calsequestrin2-knockout-mice
#9
Hsiang-Ting Ho, Senthil Thambidorai, Björn C Knollmann, George E Billman, Sandor Györke, Anuradha Kalyanasundaram
BACKGROUND: Long-term aerobic exercise alters autonomic balance, which may not be favorable in heart rate (HR)-dependent arrhythmic diseases including catecholaminergic polymorphic ventricular tachycardia (CPVT) because of preexisting bradycardia and increased sensitivity to parasympathetic stimulation. OBJECTIVE: The purpose of this study was to determine whether long-term exercise-induced autonomic adaptations modify CPVT susceptibility. METHODS: We determined exercise-induced parasympathetic effects on HR, arrhythmia incidence, and intracellular sarcoplasmic reticulum (SR) Ca2+ leak in atrial (ACM) and ventricular (VCM) cardiomyocytes, in exercised (EX) calsequestrin knockout (CASQ2-/- ) mice, a model of CPVT...
March 2018: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28982705/sk-channels-regulate-resting-properties-and-signaling-reliability-of-a-developing-fast-spiking-neuron
#10
Yihui Zhang, Hai Huang
Reliable and precise signal transmission is essential in circuits of the auditory brainstem to encode timing with submillisecond accuracy. Globular bushy cells reliably and faithfully transfer spike signals to the principal neurons of the medial nucleus of the trapezoid body (MNTB) through the giant glutamatergic synapse, the calyx of Held. Thus, the MNTB works as a relay nucleus that preserves the temporal pattern of firing at high frequency. Using whole-cell patch-clamp recordings, we observed a K(+) conductance mediated by small-conductance calcium-activated potassium (SK) channels in the MNTB neurons from rats of either sex...
November 1, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28916340/identification-of-potent-nonabsorbable-agonists-of-the-calcium-sensing-receptor-for-gi-specific-administration
#11
Steven M Sparks, Paul K Spearing, Caroline J Diaz, David J Cowan, Channa Jayawickreme, Grace Chen, Thomas J Rimele, Claudia Generaux, Lindsey T Harston, Shane G Roller
Modulation of gastrointestinal nutrient sensing pathways provides a promising a new approach for the treatment of metabolic diseases including diabetes and obesity. The calcium-sensing receptor has been identified as a key receptor involved in mineral and amino acid nutrient sensing and thus is an attractive target for modulation in the intestine. Herein we describe the optimization of gastrointestinally restricted calcium-sensing receptor agonists starting from a 3-aminopyrrolidine-containing template leading to the identification of GI-restricted agonist 19 (GSK3004774)...
October 15, 2017: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28859293/impaired-calcium-homeostasis-is-associated-with-sudden-cardiac-death-and-arrhythmias-in-a-genetic-equivalent-mouse-model-of-the-human-hrc-ser96ala-variant
#12
Christos Tzimas, Daniel M Johnson, Demetrio J Santiago, Elizabeth Vafiadaki, Demetrios A Arvanitis, Constantinos H Davos, Aimilia Varela, Nikolaos C Athanasiadis, Constantinos Dimitriou, Michalis Katsimpoulas, Stephan Sonntag, Mariya Kryzhanovska, Doron Shmerling, Stephan E Lehnart, Karin R Sipido, Evangelia G Kranias, Despina Sanoudou
Aims: The histidine-rich calcium-binding protein (HRC) Ser96Ala variant has previously been identified as a potential biomarker for ventricular arrhythmias and sudden cardiac death in patients with idiopathic dilated cardiomyopathy. Herein, the role of this variant in cardiac pathophysiology is delineated through a novel mouse model, carrying the human mutation in the homologous mouse position. Methods and results: The mouse HRC serine 81, homologous to human HRC serine 96, was mutated to alanine, using knock-in gene targeting...
September 1, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28859079/a-computational-model-of-spatio-temporal-cardiac-intracellular-calcium-handling-with-realistic-structure-and-spatial-flux-distribution-from-sarcoplasmic-reticulum-and-t-tubule-reconstructions
#13
Michael A Colman, Christian Pinali, Andrew W Trafford, Henggui Zhang, Ashraf Kitmitto
Intracellular calcium cycling is a vital component of cardiac excitation-contraction coupling. The key structures responsible for controlling calcium dynamics are the cell membrane (comprising the surface sarcolemma and transverse-tubules), the intracellular calcium store (the sarcoplasmic reticulum), and the co-localisation of these two structures to form dyads within which calcium-induced-calcium-release occurs. The organisation of these structures tightly controls intracellular calcium dynamics. In this study, we present a computational model of intracellular calcium cycling in three-dimensions (3-D), which incorporates high resolution reconstructions of these key regulatory structures, attained through imaging of tissue taken from the sheep left ventricle using serial block face scanning electron microscopy...
August 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28843346/beyond-the-critical-point-an-overview-of-excitotoxicity-calcium-overload-and-the-downstream-consequences
#14
REVIEW
Daniele Bano, Maria Ankarcrona
Over the past several decades, an overwhelming body of research has greatly expanded our understanding of the mechanisms underlying excitotoxicity in brain ischemia as well as in many chronic neurodegenerative diseases. The identification of an array of molecular targets has opened avenues for neuroprotective strategies and, consequently, has sparked considerable interest for their attractive therapeutic means as pharmacological options. The purpose of this work is to provide a general overview of neuronal excitotoxicity and the inevitable downstream consequences of Ca2+ overload...
January 10, 2018: Neuroscience Letters
https://www.readbyqxmd.com/read/28753475/presenilin-1-mutation-decreases-both-calcium-and-contractile-responses-in-cerebral-arteries
#15
Xavier Toussay, Jean-Luc Morel, Nathalie Biendon, Lolita Rotureau, François-Pierre Legeron, Marie-Charlotte Boutonnet, Yoon H Cho, Nathalie Macrez
Mutations or upregulation in presenilin 1 (PS1) gene are found in familial early-onset Alzheimer's disease or sporadic late-onset Alzheimer's disease, respectively. PS1 has been essentially studied in neurons and its mutation was shown to alter intracellular calcium (Ca2+ ) signals. Here, we showed that PS1 is expressed in smooth muscle cells (SMCs) of mouse cerebral arteries, and we assessed the effects of the deletion of exon 9 of PS1 (PS1dE9) on Ca2+ signals and contractile responses of vascular SMC. Agonist-induced contraction of cerebral vessels was significantly decreased in PS1dE9 both in vivo and ex vivo...
October 2017: Neurobiology of Aging
https://www.readbyqxmd.com/read/28739347/association-of-vitamin-d-receptor-gene-polymorphism-in-patients-with-type-2-diabetes-in-the-kashmir-valley
#16
Rawoof Malik, Rabia Farooq, Promela Mehta, Sheikh Ishaq, Insha Din, Parvaiz Shah, Sabhiya Majid
OBJECTIVES: Approx 1 billion people across various ethnic and age groups have vitamin D deficiency. The high prevalence of such a deficiency is an imperative public health issue because hypovitaminosis D is an autonomous risk factor for mortality in the general population. Beyond bone integrity and calcium homeostasis, it is involved in numerous physiologic and pathologic processes. The role of vitamin D in the pathogenesis and prevention of type 2 diabetes mellitus has sparked universal interest...
July 21, 2017: Canadian Journal of Diabetes
https://www.readbyqxmd.com/read/28731505/calcium-calmodulin-dependent-kinase-2-mediates-epac-induced-spontaneous-transient-outward-currents-in-rat-vascular-smooth-muscle
#17
Edward S A Humphries, Tomoko Kamishima, John M Quayle, Caroline Dart
KEY POINTS: The Ca(2+) and redox-sensing enzyme Ca(2+) /calmodulin-dependent kinase 2 (CaMKII) is a crucial and well-established signalling molecule in the heart and brain. In vascular smooth muscle, which controls blood flow by contracting and relaxing in response to complex Ca(2+) signals and oxidative stress, surprisingly little is known about the role of CaMKII. The vasodilator-induced second messenger cAMP can relax vascular smooth muscle via its effector, exchange protein directly activated by cAMP (Epac), by activating spontaneous transient outward currents (STOCs) that hyperpolarize the cell membrane and reduce voltage-dependent Ca(2+) influx...
September 15, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28701305/redox-and-activation-of-protein-kinase-a-dysregulates-calcium-homeostasis-in-pulmonary-vein-cardiomyocytes-of-chronic-kidney-disease
#18
Shih-Yu Huang, Yao-Chang Chen, Yu-Hsun Kao, Ming-Hsiung Hsieh, Yung-Kuo Lin, Shih-Ann Chen, Yi-Jen Chen
BACKGROUND: Chronic kidney disease (CKD) increases the occurrence of atrial fibrillation and pulmonary vein (PV) arrhythmogenesis. Calcium dysregulation and reactive oxygen species (ROS) enhance PV arrhythmogenic activity. The purposes of this study were to investigate whether CKD modulates PV electrical activity through dysregulation of calcium homeostasis and ROS. METHODS AND RESULTS: Biochemical and electrocardiographic studies were conducted in rabbits with and without CKD (induced by 150 mg/kg per day neomycin sulfate and 500 mg/kg per day cefazolin)...
July 12, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28674006/clusters-of-calcium-release-channels-harness-the-ising-phase-transition-to-confine-their-elementary-intracellular-signals
#19
Anna V Maltsev, Victor A Maltsev, Michael D Stern
Intracellular Ca signals represent a universal mechanism of cell function. Messages carried by Ca are local, rapid, and powerful enough to be delivered over the thermal noise. A higher signal-to-noise ratio is achieved by a cooperative action of Ca release channels such as IP3 receptors or ryanodine receptors arranged in clusters (release units) containing a few to several hundred release channels. The channels synchronize their openings via Ca-induced Ca release, generating high-amplitude local Ca signals known as puffs in neurons and sparks in muscle cells...
July 18, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28657075/bioinspired-onion-epithelium-like-structure-promotes-the-maturation-of-cardiomyocytes-derived-from-human-pluripotent-stem-cells
#20
Cong Xu, Li Wang, Yue Yu, Fangchao Yin, Xiaoqing Zhang, Lei Jiang, Jianhua Qin
Organized cardiomyocyte alignment is critical to maintain the mechanical properties of the heart. In this study, we present a new and simple strategy to fabricate a biomimetic microchip designed with an onion epithelium-like structure and investigate the guided behavior of human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) on the substrate. The hiPSC-CMs were observed to be confined by the three dimensional surficial features morphologically, analogous to the in vivo microenvironment, and exhibited an organized anisotropic alignment on the onion epithelium-like structure with good beating function...
August 22, 2017: Biomaterials Science
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