The Linear Parameters and the Decoupling Matrix for Linearly Coupled Motion in 6 Dimensional Phase Space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parzen, George

It will be shown that starting from a coordinate system where the 6 phase space coordinates are linearly coupled, one can go to a new coordinate system, where the motion is uncoupled, by means of a linear transformation. The original coupled coordinates and the new uncoupled coordinates are related by a 6 x 6 matrix, R. R will be called the decoupling matrix. It will be shown that of the 36 elements of the 6 x 6 decoupling matrix R, only 12 elements are independent. This may be contrasted with the results for motion in 4- dimensional phase space, wheremore » R has 4 independent elements. A set of equations is given from which the 12 elements of R can be computed from the one period transfer matrix. This set of equations also allows the linear parameters, the β i,α i, i = 1, 3, for the uncoupled coordinates, to be computed from the one period transfer matrix. An alternative procedure for computing the linear parameters,β i,α i, i = 1, 3, and the 12 independent elements of the decoupling matrix R is also given which depends on computing the eigenvectors of the one period transfer matrix. These results can be used in a tracking program, where the one period transfer matrix can be computed by multiplying the transfer matrices of all the elements in a period, to compute the linear parameters α i and β i, i = 1, 3, and the elements of the decoupling matrix R. The procedure presented here for studying coupled motion in 6-dimensional phase space can also be applied to coupled motion in 4-dimensional phase space, where it may be a useful alternative procedure to the procedure presented by Edwards and Teng. In particular, it gives a simpler programing procedure for computing the beta functions and the emittances for coupled motion in 4-dimensional phase space.« less

The linear parameters and the decoupling matrix for linearly coupled motion in 6 dimensional phase space. Informal report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parzen, G.

It will be shown that starting from a coordinate system where the 6 phase space coordinates are linearly coupled, one can go to a new coordinate system, where the motion is uncoupled, by means of a linear transformation. The original coupled coordinates and the new uncoupled coordinates are related by a 6 {times} 6 matrix, R. R will be called the decoupling matrix. It will be shown that of the 36 elements of the 6 {times} 6 decoupling matrix R, only 12 elements are independent. This may be contrasted with the results for motion in 4-dimensional phase space, where Rmore » has 4 independent elements. A set of equations is given from which the 12 elements of R can be computed from the one period transfer matrix. This set of equations also allows the linear parameters, {beta}{sub i}, {alpha}{sub i} = 1, 3, for the uncoupled coordinates, to be computed from the one period transfer matrix. An alternative procedure for computing the linear parameters, the {beta}{sub i}, {alpha}{sub i} i = 1, 3, and the 12 independent elements of the decoupling matrix R is also given which depends on computing the eigenvectors of the one period transfer matrix. These results can be used in a tracking program, where the one period transfer matrix can be computed by multiplying the transfer matrices of all the elements in a period, to compute the linear parameters {alpha}{sub i} and {beta}{sub i}, i = 1, 3, and the elements of the decoupling matrix R. The procedure presented here for studying coupled motion in 6-dimensional phase space can also be applied to coupled motion in 4-dimensional phase space, where it may be a useful alternative procedure to the procedure presented by Edwards and Teng. In particular, it gives a simpler programming procedure for computing the beta functions and the emittances for coupled motion in 4-dimensional phase space.« less

Diastolic chamber properties of the left ventricle assessed by global fitting of pressure-volume data: improving the gold standard of diastolic function.

PubMed

Bermejo, Javier; Yotti, Raquel; Pérez del Villar, Candelas; del Álamo, Juan C; Rodríguez-Pérez, Daniel; Martínez-Legazpi, Pablo; Benito, Yolanda; Antoranz, J Carlos; Desco, M Mar; González-Mansilla, Ana; Barrio, Alicia; Elízaga, Jaime; Fernández-Avilés, Francisco

2013-08-15

In cardiovascular research, relaxation and stiffness are calculated from pressure-volume (PV) curves by separately fitting the data during the isovolumic and end-diastolic phases (end-diastolic PV relationship), respectively. This method is limited because it assumes uncoupled active and passive properties during these phases, it penalizes statistical power, and it cannot account for elastic restoring forces. We aimed to improve this analysis by implementing a method based on global optimization of all PV diastolic data. In 1,000 Monte Carlo experiments, the optimization algorithm recovered entered parameters of diastolic properties below and above the equilibrium volume (intraclass correlation coefficients = 0.99). Inotropic modulation experiments in 26 pigs modified passive pressure generated by restoring forces due to changes in the operative and/or equilibrium volumes. Volume overload and coronary microembolization caused incomplete relaxation at end diastole (active pressure > 0.5 mmHg), rendering the end-diastolic PV relationship method ill-posed. In 28 patients undergoing PV cardiac catheterization, the new algorithm reduced the confidence intervals of stiffness parameters by one-fifth. The Jacobian matrix allowed visualizing the contribution of each property to instantaneous diastolic pressure on a per-patient basis. The algorithm allowed estimating stiffness from single-beat PV data (derivative of left ventricular pressure with respect to volume at end-diastolic volume intraclass correlation coefficient = 0.65, error = 0.07 ± 0.24 mmHg/ml). Thus, in clinical and preclinical research, global optimization algorithms provide the most complete, accurate, and reproducible assessment of global left ventricular diastolic chamber properties from PV data. Using global optimization, we were able to fully uncouple relaxation and passive PV curves for the first time in the intact heart.

Classical-processing and quantum-processing signal separation methods for qubit uncoupling

NASA Astrophysics Data System (ADS)

Deville, Yannick; Deville, Alain

2012-12-01

The Blind Source Separation problem consists in estimating a set of unknown source signals from their measured combinations. It was only investigated in a non-quantum framework up to now. We propose its first quantum extensions. We thus introduce the Quantum Source Separation field, investigating both its blind and non-blind configurations. More precisely, we show how to retrieve individual quantum bits (qubits) only from the global state resulting from their undesired coupling. We consider cylindrical-symmetry Heisenberg coupling, which e.g. occurs when two electron spins interact through exchange. We first propose several qubit uncoupling methods which typically measure repeatedly the coupled quantum states resulting from individual qubits preparations, and which then statistically process the classical data provided by these measurements. Numerical tests prove the effectiveness of these methods. We then derive a combination of quantum gates for performing qubit uncoupling, thus avoiding repeated qubit preparations and irreversible measurements.

Transition in coupled replicas may not imply a finite-temperature ideal glass transition in glass-forming systems.

PubMed

Garrahan, Juan P

2014-03-01

A key open question in the glass transition field is whether a finite temperature thermodynamic transition to the glass state exists or not. Recent simulations of coupled replicas in atomistic models have found signatures of a static transition as a function of replica coupling. This can be viewed as evidence of an associated thermodynamic glass transition in the uncoupled system. We demonstrate here that a different interpretation is possible. We consider the triangular plaquette model, an interacting spin system which displays (East model-like) glassy dynamics in the absence of any static transition. We show that when two replicas are coupled, there is a curve of equilibrium phase transitions, between phases of small and large overlap, in the temperature-coupling plane (located on the self-dual line of an exact temperature-coupling duality of the system) which ends at a critical point. Crucially, in the limit of vanishing coupling the finite temperature transition disappears, and the uncoupled system is in the disordered phase at all temperatures. We discuss an interpretation of atomistic simulations in light of this result.

Weak wide-band signal detection method based on small-scale periodic state of Duffing oscillator

NASA Astrophysics Data System (ADS)

Hou, Jian; Yan, Xiao-peng; Li, Ping; Hao, Xin-hong

2018-03-01

The conventional Duffing oscillator weak signal detection method, which is based on a strong reference signal, has inherent deficiencies. To address these issues, the characteristics of the Duffing oscillatorʼs phase trajectory in a small-scale periodic state are analyzed by introducing the theory of stopping oscillation system. Based on this approach, a novel Duffing oscillator weak wide-band signal detection method is proposed. In this novel method, the reference signal is discarded, and the to-be-detected signal is directly used as a driving force. By calculating the cosine function of a phase space angle, a single Duffing oscillator can be used for weak wide-band signal detection instead of an array of uncoupled Duffing oscillators. Simulation results indicate that, compared with the conventional Duffing oscillator detection method, this approach performs better in frequency detection intervals, and reduces the signal-to-noise ratio detection threshold, while improving the real-time performance of the system. Project supported by the National Natural Science Foundation of China (Grant No. 61673066).

p38 mitogen-activated protein kinase is involved in arginase-II-mediated eNOS-Uncoupling in Obesity

PubMed Central

2014-01-01

Background Endothelial nitric oxide synthase (eNOS)-uncoupling links obesity-associated insulin resistance and type-II diabetes to the increased incidence of cardiovascular disease. Studies have indicated that increased arginase is involved in eNOS-uncoupling through competing with the substrate L-arginine. Given that arginase-II (Arg-II) exerts some of its biological functions through crosstalk with signal transduction pathways, and that p38 mitogen-activated protein kinase (p38mapk) is involved in eNOS-uncoupling, we investigated here whether p38mapk is involved in Arg-II-mediated eNOS-uncoupling in a high fat diet (HFD)-induced obesity mouse model. Methods Obesity was induced in wild type (WT) and Arg-II-deficient (Arg-II-/-) mice on C57BL/6 J background by high-fat diet (HFD, 55% fat) for 14 weeks starting from age of 7 weeks. The entire aortas were isolated and subjected to 1) immunoblotting analysis of the protein level of eNOS, Arg-II and p38mapk activation; 2) arginase activity assay; 3) endothelium-dependent and independent vasomotor responses; 4) en face staining of superoxide anion and NO production with Dihydroethidium and 4,5-Diaminofluorescein Diacetate, respectively, to assess eNOS-uncoupling. To evaluate the role of p38mapk, isolated aortas were treated with p38mapk inhibitor SB203580 (10 μmol/L, 1 h) prior to the analysis. In addition, the role of p38mapk in Arg-II-induced eNOS-uncoupling was investigated in cultured human endothelial cells overexpressing Arg-II in the absence or presence of shRNA against p38mapk. Results HFD enhanced Arg-II expression/activity and p38mapk activity, which was associated with eNOS-uncoupling as revealed by decreased NO and enhanced L-NAME-inhibitable superoxide in aortas of WT obese mice. In accordance, WT obese mice revealed decreased endothelium-dependent relaxations to acetylcholine despite of higher eNOS protein level, whereas Arg-II-/- obese mice were protected from HFD-induced eNOS-uncoupling and endothelial dysfunction, which was associated with reduced p38mapk activation in aortas of the Arg-II-/- obese mice. Moreover, overexpression of Arg-II in human endothelial cells caused eNOS-uncoupling and augmented p38mapk activation. The Arg-II-induced eNOS-uncoupling was prevented by silencing p38mapk. Furthermore, pharmacological inhibition of p38mapk recouples eNOS in isolated aortas from WT obese mice. Conclusions Taking together, we demonstrate here for the first time that Arg-II causes eNOS-uncoupling through activation of p38 mapk in HFD-induced obesity. PMID:25034973

Structure of the Madden-Julian oscillation in coupled and uncoupled versions of the superparameterized community atmosphere model

NASA Astrophysics Data System (ADS)

Benedict, James J.

The Madden-Julian Oscillation (MJO), an eastward-propagating atmospheric disturbance resembling a transient Walker cell, dominates intraseasonal (20--100 days) variability in the tropical Indian and West Pacific Ocean regions. The phenomenon is most active during the Northern Hemisphere winter and is characterized by cyclic periods of suppressed (dry phase) and active (wet phase) cloudiness and precipitation. Numerous complexities---multi-scale interactions of moist convection and large-scale wave dynamics, air-sea fluxes and feedbacks, topographical impacts, and tropical-extratropical interactions---challenge our ability to fully understand the MJO and result in its poor representation in most current general circulation models (GCMs). This study examines the representation of the MJO in a modified version of the NCAR Community Atmosphere Model (CAM). The modifications involve substituting conventional boundary layer, turbulence, and cloud parameterizations with a configuration of cloud-resolving models (CRMs) embedded into each GCM grid cell in a technique termed "superparameterization" (SP). Unlike many GCMs including the standard CAM, the SP-CAM displays robust intraseasonal convective variability. Two SP-CAM simulations are utilized in this study: one forced by observed sea-surface temperatures (SSTs; "uncoupled") and a second identical to the first except for a new treatment of tropical SSTs in which a simplified mixed-layer ocean model is used to predict SST anomalies that are coupled to the atmosphere ("coupled"). Key physical features of the MJO are captured in the uncoupled SP-CAM. Ahead (east) of the disturbance there is meridional boundary layer moisture convergence and a vertical progression of warmth, moisture, and convective heating from the lower to upper troposphere. The space-time dynamical response to convective heating is also reproduced, especially the vertical structure of anomalous westerly wind and its migration into the region of heavy rainfall as the disturbance propagates eastward. Advective drying processes in the MJO wake are also represented well. The coupled SP-CAM shows more realistic MJO eastward propagation, signal coherence and spatial structure relative to the uncoupled SP-CAM. The improvement varies with longitude but generally stems from better space-time relationships among MJO convective heating, its dynamical response, SSTs, surface fluxes, boundary layer properties, and vertical moisture structure. Coupled MJO events in the Indian Ocean display more realistic intensity; in the West Pacific, the coupled SP-CAM overestimates convective strength but shows an improved vertical structure relative to the uncoupled SP-CAM. Biases related to MJO convection are also examined. Overestimated convective intensity in the West Pacific appears to be linked to basic state biases, Maritime Continent topographical impacts, unrealistic convection-wind-evaporation feedbacks, and the neglect of convective momentum transport in the model. Phase errors between observed and simulated boundary layer moisture appear to stem from an unrealistic representation of shallow cumuli.

Micromechanics based simulation of ductile fracture in structural steels

NASA Astrophysics Data System (ADS)

Yellavajjala, Ravi Kiran

The broader aim of this research is to develop fundamental understanding of ductile fracture process in structural steels, propose robust computational models to quantify the associated damage, and provide numerical tools to simplify the implementation of these computational models into general finite element framework. Mechanical testing on different geometries of test specimens made of ASTM A992 steels is conducted to experimentally characterize the ductile fracture at different stress states under monotonic and ultra-low cycle fatigue (ULCF) loading. Scanning electron microscopy studies of the fractured surfaces is conducted to decipher the underlying microscopic damage mechanisms that cause fracture in ASTM A992 steels. Detailed micromechanical analyses for monotonic and cyclic loading are conducted to understand the influence of stress triaxiality and Lode parameter on the void growth phase of ductile fracture. Based on monotonic analyses, an uncoupled micromechanical void growth model is proposed to predict ductile fracture. This model is then incorporated in to finite element program as a weakly coupled model to simulate the loss of load carrying capacity in the post microvoid coalescence regime for high triaxialities. Based on the cyclic analyses, an uncoupled micromechanics based cyclic void growth model is developed to predict the ULCF life of ASTM A992 steels subjected to high stress triaxialities. Furthermore, a computational fracture locus for ASTM A992 steels is developed and incorporated in to finite element program as an uncoupled ductile fracture model. This model can be used to predict the ductile fracture initiation under monotonic loading in a wide range of triaxiality and Lode parameters. Finally, a coupled microvoid elongation and dilation based continuum damage model is proposed, implemented, calibrated and validated. This model is capable of simulating the local softening caused by the various phases of ductile fracture process under monotonic loading for a wide range of stress states. Novel differentiation procedures based on complex analyses along with existing finite difference methods and automatic differentiation are extended using perturbation techniques to evaluate tensor derivatives. These tensor differentiation techniques are then used to automate nonlinear constitutive models into implicit finite element framework. Finally, the efficiency of these automation procedures is demonstrated using benchmark problems.

Solving Modal Equations of Motion with Initial Conditions Using MSC/NASTRAN DMAP. Part 2; Coupled Versus Uncoupled Integration

NASA Technical Reports Server (NTRS)

Barnett, Alan R.; Ibrahim, Omar M.; Abdallah, Ayman A.; Sullivan, Timothy L.

1993-01-01

By utilizing MSC/NASTRAN DMAP (Direct Matrix Abstraction Program) in an existing NASA Lewis Research Center coupled loads methodology, solving modal equations of motion with initial conditions is possible using either coupled (Newmark-Beta) or uncoupled (exact mode superposition) integration available within module TRD1. Both the coupled and newly developed exact mode superposition methods have been used to perform transient analyses of various space systems. However, experience has shown that in most cases, significant time savings are realized when the equations of motion are integrated using the uncoupled solver instead of the coupled solver. Through the results of a real-world engineering analysis, advantages of using the exact mode superposition methodology are illustrated.

When frequencies never synchronize: the golden mean and the resting EEG.

PubMed

Pletzer, Belinda; Kerschbaum, Hubert; Klimesch, Wolfgang

2010-06-04

The classical frequency bands of the EEG can be described as a geometric series with a ratio (between neighbouring frequencies) of 1.618, which is the golden mean. Here we show that a synchronization of the excitatory phases of two oscillations with frequencies f1 and f2 is impossible (in a mathematical sense) when their ratio equals the golden mean, because their excitatory phases never meet. Thus, in a mathematical sense, the golden mean provides a totally uncoupled ('desynchronized') processing state which most likely reflects a 'resting' brain, which is not involved in selective information processing. However, excitatory phases of the f1- and f2-oscillations occasionally come close enough to coincide in a physiological sense. These coincidences are more frequent, the higher the frequencies f1 and f2. We demonstrate that the pattern of excitatory phase meetings provided by the golden mean as the 'most irrational' number is least frequent and most irregular. Thus, in a physiological sense, the golden mean provides (i) the highest physiologically possible desynchronized state in the resting brain, (ii) the possibility for spontaneous and most irregular (!) coupling and uncoupling between rhythms and (iii) the opportunity for a transition from resting state to activity. These characteristics have already been discussed to lay the ground for a healthy interplay between various physiological processes (Buchmann, 2002). Copyright 2010 Elsevier B.V. All rights reserved.

The intraannual variability of land-atmosphere coupling over North America in the Canadian Regional Climate Model (CRCM5)

NASA Astrophysics Data System (ADS)

Yang Kam Wing, G.; Sushama, L.; Diro, G. T.

2016-12-01

This study investigates the intraannual variability of soil moisture-temperature coupling over North America. To this effect, coupled and uncoupled simulations are performed with the fifth-generation Canadian Regional Climate Model (CRCM5), driven by ERA-Interim. In coupled simulations, land and atmosphere interact freely; in uncoupled simulations, the interannual variability of soil moisture is suppressed by prescribing climatological values for soil liquid and frozen water contents. The study also explores projected changes to coupling by comparing coupled and uncoupled CRCM5 simulations for current (1981-2010) and future (2071-2100) periods, driven by the Canadian Earth System Model. Coupling differs for the northern and southern parts of North America. Over the southern half, it is persistent throughout the year while for the northern half, strongly coupled regions generally follow the freezing line during the cold months. Detailed analysis of the southern Canadian Prairies reveals seasonal differences in the underlying coupling mechanism. During spring and fall, as opposed to summer, the interactive soil moisture phase impacts the snow depth and surface albedo, which further impacts the surface energy budget and thus the surface air temperature; the air temperature then influences the snow depth in a feedback loop. Projected changes to coupling are also season specific: relatively drier soil conditions strengthen coupling during summer, while changes in soil moisture phase, snow depth, and cloud cover impact coupling during colder months. Furthermore, results demonstrate that soil moisture variability amplifies the frequency of temperature extremes over regions of strong coupling in current and future climates.

Liquid-phase tuning of porous PVDF-TrFE film on flexible substrate for energy harvesting

NASA Astrophysics Data System (ADS)

Chen, Dajing; Chen, Kaina; Brown, Kristopher; Hang, Annie; Zhang, John X. J.

2017-04-01

Emerging wearable and implantable biomedical energy harvesting devices demand efficient power conversion, flexible structures, and lightweight construction. This paper presents Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) micro-porous structures, which can be tuned to specific mechanical flexibilities and optimized for piezoelectric power conversion. Specifically, the water vapor phase separation method was developed to control microstructure formation, pore diameter, porosity, and mechanical flexibility. Furthermore, we investigated the effects of the piezoelectric layer to supporting layer Young's modulus ratio, through using both analytical calculation and experimentation. Both structure flexibility and stress-induced voltage were considered in the analyses. Specification of electromechanical coupling efficiency, made possible by carefully designed three-dimensional porous structures, was shown to increase the power output by five-fold relative to uncoupled structures. Therefore, flexible PVDF-TrFE films with tunable microstructures, paired with substrates of different rigidities, provide highly efficient designs of compact piezoelectric energy generating devices.

Development and evaluation of the aerosol dynamic and gas phase chemistry model ADCHEM

NASA Astrophysics Data System (ADS)

Roldin, P.; Swietlicki, E.; Schurgers, G.; Arneth, A.; Lehtinen, K. E. J.; Boy, M.; Kulmala, M.

2010-08-01

The aim of this work was to develop a model ideally suited for detailed studies on aerosol dynamics, gas and particle phase chemistry within urban plumes, from local scale (1×1 km2) to regional or global scale. This article describes and evaluates the trajectory model for Aerosol Dynamics, gas and particle phase CHEMistry and radiative transfer (ADCHEM), which has been developed and used at Lund University since 2007. The model treats both vertical and horizontal dispersion perpendicular to an air mass trajectory (2-space dimensions), which is not treated in Lagrangian box-models (0-space dimensions). The Lagrangian approach enables a more detailed representation of the aerosol dynamics, gas and particle phase chemistry and a finer spatial and temporal resolution compared to that of available regional 3D-CTMs. These features make it among others ideally suited for urban plume studies. The aerosol dynamics model includes Brownian coagulation, dry deposition, wet deposition, in-cloud processing, condensation, evaporation, primary particle emissions and homogeneous nucleation. The gas phase chemistry model calculates the gas phase concentrations of 63 different species, using 119 different chemical reactions. Daily isoprene and monoterpene emissions from European forests were simulated separately with the vegetation model LPJ-GUESS, and included as input to ADCHEM. ADCHEM was used to simulate the ageing of the urban plumes from the city of Malmö in Southern Sweden (280 000 inhabitants). Several sensitivity tests were performed concerning the number of size bins, size structure method, coupled or uncoupled condensation, the volatility basis set (VBS) or traditional 2-product model for secondary organic aerosol formation, different aerosol dynamic processes and vertical and horizontal mixing. The simulations show that the full-stationary size structure gives accurate results with little numerical diffusion when more than 50 size bins are used between 1.5 and 2500 nm, while the moving-center method is preferable when only a few size bins are selected. The particle number size distribution in the center of the urban plume from Malmö is mainly affected by dry deposition, coagulation and condensation, and is relatively insensitive to moderate variations in the vertical and horizontal mixing, as long as the mixing height is relatively uniform. The modeled PM2.5 was dominated by organics, nitrate, sulfate and ammonium. If treating the condensation of HNO3 and NH3 as a coupled process (pH independent) the model gave lower nitrate PM2.5 values than if considering uncoupled condensation. However, both methods gave similar and significant temporal variation in the particulate nitrate content, primarily due to fluctuation in the relative humidity.

Reduced heart rate variability: an indicator of cardiac uncoupling and diminished physiologic reserve in 1,425 trauma patients.

PubMed

Morris, John A; Norris, Patrick R; Ozdas, Asli; Waitman, Lemuel R; Harrell, Frank E; Williams, Anna E; Cao, Hanqing; Jenkins, Judith M

2006-06-01

Measurements of a patient's physiologic reserve (age, injury severity, admission lactic acidosis, transfusion requirements, and coagulopathy) reflect robustness of response to surgical insult. We have previously shown that cardiac uncoupling (reduced heart rate variability, HRV) in the first 24 hours after injury correlates with mortality and autonomic nervous system failure. We hypothesized: Deteriorating physiologic reserve correlates with reduced HRV and cardiac uncoupling. There were 1,425 trauma ICU patients that satisfied the inclusion criteria. Differences in mortality across categorical measurements of the domains of physiologic reserve were assessed using the chi test. The relationship of cardiac uncoupling and physiologic reserve was examined using multivariate logistic regression models for various levels of cardiac uncoupling (>0 through 28% reduced HRV in the first 24 hours). Of these, 797 (55.9%) patients exhibited cardiac uncoupling. Deteriorating measures of physiologic reserve reflected increased risk of death. Measures of acidosis (admission lactate, time to lactate normalization, and lactate deterioration over the first 24 hours), coagulopathy, age, and injury severity contributed significantly to the risk of cardiac uncoupling (area under receiver operator curve, ROC=0.73). The association between deteriorating reserve and cardiac uncoupling increases with the threshold for uncoupling (ROC=0.78). Reduced heart rate variability is a new biomarker reflecting the loss of command and control of the heart (cardiac uncoupling). Risk of cardiac uncoupling increases significantly as a patient's physiologic reserve deteriorates and physiologic exhaustion approaches. Cardiac uncoupling provides a noninvasive, overall measure of a patient's clinical trajectory over the first 24 hours of ICU stay.

Understanding transient uncoupling induced synchronization through modified dynamic coupling

NASA Astrophysics Data System (ADS)

Ghosh, Anupam; Godara, Prakhar; Chakraborty, Sagar

2018-05-01

An important aspect of the recently introduced transient uncoupling scheme is that it induces synchronization for large values of coupling strength at which the coupled chaotic systems resist synchronization when continuously coupled. However, why this is so is an open problem? To answer this question, we recall the conventional wisdom that the eigenvalues of the Jacobian of the transverse dynamics measure whether a trajectory at a phase point is locally contracting or diverging with respect to another nearby trajectory. Subsequently, we go on to highlight a lesser appreciated fact that even when, under the corresponding linearised flow, the nearby trajectory asymptotically diverges away, its distance from the reference trajectory may still be contracting for some intermediate period. We term this phenomenon transient decay in line with the phenomenon of the transient growth. Using these facts, we show that an optimal coupling region, i.e., a region of the phase space where coupling is on, should ideally be such that at any of the constituent phase point either the maximum of the real parts of the eigenvalues is negative or the magnitude of the positive maximum is lesser than that of the negative minimum. We also invent and employ a modified dynamics coupling scheme—a significant improvement over the well-known dynamic coupling scheme—as a decisive tool to justify our results.

Low Concentrations of Uncouplers of Oxidative Phosphorylation Prevent Inflammatory Activation of Endothelial Cells by Tumor Necrosis Factor.

PubMed

Romaschenko, V P; Zinovkin, R A; Galkin, I I; Zakharova, V V; Panteleeva, A A; Tokarchuk, A V; Lyamzaev, K G; Pletjushkina, O Yu; Chernyak, B V; Popova, E N

2015-05-01

In endothelial cells, mitochondria play an important regulatory role in physiology as well as in pathophysiology related to excessive inflammation. We have studied the effect of low doses of mitochondrial uncouplers on inflammatory activation of endothelial cells using the classic uncouplers 2,4-dinitrophenol and 4,5,6,7-tetrachloro-2-trifluoromethylbenzimidazole, as well as the mitochondria-targeted cationic uncoupler dodecyltriphenylphosphonium (C12TPP). All of these uncouplers suppressed the expression of E-selectin, adhesion molecules ICAM1 and VCAM1, as well as the adhesion of neutrophils to endothelium induced by tumor necrosis factor (TNF). The antiinflammatory action of the uncouplers was at least partially mediated by the inhibition of NFκB activation due to a decrease in phosphorylation of the inhibitory subunit IκBα. The dynamic concentration range for the inhibition of ICAM1 expression by C12TPP was three orders of magnitude higher compared to the classic uncouplers. Probably, the decrease in membrane potential inhibited the accumulation of penetrating cations into mitochondria, thus lowering the uncoupling activity and preventing further loss of mitochondrial potential. Membrane potential recovery after the removal of the uncouplers did not abolish its antiinflammatory action. Thus, mild uncoupling could induce TNF resistance in endothelial cells. We found no significant stimulation of mitochondrial biogenesis or autophagy by the uncouplers. However, we observed a decrease in the relative amount of fragmented mitochondria. The latter may significantly change the signaling properties of mitochondria. Earlier we showed that both classic and mitochondria-targeted antioxidants inhibited the TNF-induced NFκB-dependent activation of endothelium. The present data suggest that the antiinflammatory effect of mild uncoupling is related to its antioxidant action.

Acute Knockdown of Uncoupling Protein-2 Increases Uncoupling via the Adenine Nucleotide Transporter and Decreases Oxidative Stress in Diabetic Kidneys

PubMed Central

Friederich-Persson, Malou; Aslam, Shakil; Nordquist, Lina; Welch, William J.; Wilcox, Christopher S.; Palm, Fredrik

2012-01-01

Increased O2 metabolism resulting in chronic hypoxia is common in models of endstage renal disease. Mitochondrial uncoupling increases O2 consumption but the ensuing reduction in mitochondrial membrane potential may limit excessive oxidative stress. The present study addressed the hypothesis that mitochondrial uncoupling regulates mitochondria function and oxidative stress in the diabetic kidney. Isolated mitochondria from kidney cortex of control and streptozotocin-induced diabetic rats were studied before and after siRNA knockdown of uncoupling protein-2 (UCP-2). Diabetes resulted in increased UCP-2 protein expression and UCP-2-mediated uncoupling, but normal mitochondria membrane potential. This uncoupling was inhibited by GDP, which also increased the membrane potential. siRNA reduced UCP-2 protein expression in controls and diabetics (−30–50%), but paradoxically further increased uncoupling and markedly reduced the membrane potential. This siRNA mediated uncoupling was unaffected by GDP but was blocked by ADP and carboxyatractylate (CAT). Mitochondria membrane potential after UCP-2 siRNA was unaffected by GDP but increased by CAT. This demonstrated that further increased mitochondria uncoupling after siRNA towards UCP-2 is mediated through the adenine nucleotide transporter (ANT). The increased oxidative stress in the diabetic kidney, manifested as increased thiobarbituric acids, was reduced by knocking down UCP-2 whereas whole-body oxidative stress, manifested as increased circulating malondialdehyde, remained unaffected. All parameters investigated were unaffected by scrambled siRNA. In conclusion, mitochondrial uncoupling via UCP-2 regulates mitochondria membrane potential in diabetes. However, blockade of the diabetes-induced upregulation of UCP- 2 results in excessive uncoupling and reduced oxidative stress in the kidney via activation of ANT. PMID:22768304

30 CFR 57.14215 - Coupling or uncoupling cars.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Coupling or uncoupling cars. 57.14215 Section... and Equipment Safety Practices and Operational Procedures § 57.14215 Coupling or uncoupling cars. Prior to coupling or uncoupling cars manually, trains shall be brought to a complete stop, and then...

30 CFR 57.14215 - Coupling or uncoupling cars.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Coupling or uncoupling cars. 57.14215 Section... and Equipment Safety Practices and Operational Procedures § 57.14215 Coupling or uncoupling cars. Prior to coupling or uncoupling cars manually, trains shall be brought to a complete stop, and then...

30 CFR 56.14215 - Coupling or uncoupling cars.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Coupling or uncoupling cars. 56.14215 Section... Equipment Safety Practices and Operational Procedures § 56.14215 Coupling or uncoupling cars. Prior to coupling or uncoupling cars manually, trains shall be brought to a complete stop, and then moved at minimum...

30 CFR 56.14215 - Coupling or uncoupling cars.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Coupling or uncoupling cars. 56.14215 Section... Equipment Safety Practices and Operational Procedures § 56.14215 Coupling or uncoupling cars. Prior to coupling or uncoupling cars manually, trains shall be brought to a complete stop, and then moved at minimum...

30 CFR 56.14215 - Coupling or uncoupling cars.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Coupling or uncoupling cars. 56.14215 Section... Equipment Safety Practices and Operational Procedures § 56.14215 Coupling or uncoupling cars. Prior to coupling or uncoupling cars manually, trains shall be brought to a complete stop, and then moved at minimum...

30 CFR 56.14215 - Coupling or uncoupling cars.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Coupling or uncoupling cars. 56.14215 Section... Equipment Safety Practices and Operational Procedures § 56.14215 Coupling or uncoupling cars. Prior to coupling or uncoupling cars manually, trains shall be brought to a complete stop, and then moved at minimum...

30 CFR 57.14215 - Coupling or uncoupling cars.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Coupling or uncoupling cars. 57.14215 Section... and Equipment Safety Practices and Operational Procedures § 57.14215 Coupling or uncoupling cars. Prior to coupling or uncoupling cars manually, trains shall be brought to a complete stop, and then...

30 CFR 57.14215 - Coupling or uncoupling cars.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Coupling or uncoupling cars. 57.14215 Section... and Equipment Safety Practices and Operational Procedures § 57.14215 Coupling or uncoupling cars. Prior to coupling or uncoupling cars manually, trains shall be brought to a complete stop, and then...

30 CFR 57.14215 - Coupling or uncoupling cars.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Coupling or uncoupling cars. 57.14215 Section... and Equipment Safety Practices and Operational Procedures § 57.14215 Coupling or uncoupling cars. Prior to coupling or uncoupling cars manually, trains shall be brought to a complete stop, and then...

30 CFR 56.14215 - Coupling or uncoupling cars.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Coupling or uncoupling cars. 56.14215 Section... Equipment Safety Practices and Operational Procedures § 56.14215 Coupling or uncoupling cars. Prior to coupling or uncoupling cars manually, trains shall be brought to a complete stop, and then moved at minimum...

Aeroelasticity of wing and wing-body configurations on parallel computers

NASA Technical Reports Server (NTRS)

Byun, Chansup

1995-01-01

The objective of this research is to develop computationally efficient methods for solving aeroelasticity problems on parallel computers. Both uncoupled and coupled methods are studied in this research. For the uncoupled approach, the conventional U-g method is used to determine the flutter boundary. The generalized aerodynamic forces required are obtained by the pulse transfer-function analysis method. For the coupled approach, the fluid-structure interaction is obtained by directly coupling finite difference Euler/Navier-Stokes equations for fluids and finite element dynamics equations for structures. This capability will significantly impact many aerospace projects of national importance such as Advanced Subsonic Civil Transport (ASCT), where the structural stability margin becomes very critical at the transonic region. This research effort will have direct impact on the High Performance Computing and Communication (HPCC) Program of NASA in the area of parallel computing.

Synchrony of two uncoupled neurons under half wave sine current stimulation

NASA Astrophysics Data System (ADS)

Peng, Yueping; Wang, Jue; Jian, Zhong

2009-04-01

Two uncoupled Hindmarsh-Rose neurons under different initial discharge patterns are stimulated by the half wave sine current; and the synchronization mechanism of the two neurons is discussed by analyzing their membrane potentials and their interspike interval (ISI) distribution. Under the half wave sine current stimulation, the two uncoupled neurons under different initial conditions, whose parameter r (the parameter r is related to the membrane penetration of calcium ion, and reflects the changing speed of the slow adaptation current) is different or the same, can realize discharge synchronization (phase synchronization) or the full synchronization (state synchronization). The synchronization characteristics are mainly related to the frequency and the amplitude of the half wave sine current, and are little related to the parameter r and the initial state of the two neurons. This investigation shows the mechanism of the current's amplitude and its frequency affecting the synchronization process of neurons, and the neurons' discharge patterns and synchronization process can be adjusted and controlled by the current's amplitude and its frequency. This result is of far reaching importance to study synchronization and encode of many neurons or neural network, and provides the theoretic basis for studying the mechanism of some nervous diseases such as epilepsy and Alzheimer's disease by the slow wave of EEG.

Metastable solidification of hypereutectic Co 2Si-CoSi composition: Microstructural studies and in-situ observations

DOE PAGES

Wang, Yeqing; Gao, Jianrong; Kolbe, Matthias; ...

2017-09-18

Metastable solidification of undercooled Co 60Si 40 melts was investigated by microstructural studies and in-situ high-energy X-ray diffraction. Five solidification paths were identified. Three of them were observed at low undercoolings, which show uncoupled and coupled growth of stable β-Co 2Si and CoSi compounds. The other paths were observed at high undercoolings, which show peritectic and primary crystallization of a metastable Co 5Si 3 compound. The β-Co 2Si and Co 5Si 3 compounds crystallize into a hexagonal crystal structure and experience solid-state decomposition. Microstructure formation depends on solidification path. The coupled and uncoupled growth of the stable compounds produces amore » regular lamellar eutectic structure and an anomalous eutectic structure, respectively. The crystallization and solid-state decomposition of the metastable Co 5Si 3 compound brings about a fine-grained two-phase mixture, which represents another type of anomalous eutectic structure. Here, the results provide proof of two rare mechanisms of anomalous eutectic formation and shed light onto metastable phase relations in the undercooled region of the Co-Si system.« less

Metastable solidification of hypereutectic Co 2Si-CoSi composition: Microstructural studies and in-situ observations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yeqing; Gao, Jianrong; Kolbe, Matthias

Metastable solidification of undercooled Co 60Si 40 melts was investigated by microstructural studies and in-situ high-energy X-ray diffraction. Five solidification paths were identified. Three of them were observed at low undercoolings, which show uncoupled and coupled growth of stable β-Co 2Si and CoSi compounds. The other paths were observed at high undercoolings, which show peritectic and primary crystallization of a metastable Co 5Si 3 compound. The β-Co 2Si and Co 5Si 3 compounds crystallize into a hexagonal crystal structure and experience solid-state decomposition. Microstructure formation depends on solidification path. The coupled and uncoupled growth of the stable compounds produces amore » regular lamellar eutectic structure and an anomalous eutectic structure, respectively. The crystallization and solid-state decomposition of the metastable Co 5Si 3 compound brings about a fine-grained two-phase mixture, which represents another type of anomalous eutectic structure. Here, the results provide proof of two rare mechanisms of anomalous eutectic formation and shed light onto metastable phase relations in the undercooled region of the Co-Si system.« less

Multiple, simultaneous, independent gradients for a versatile multidimensional liquid chromatography. Part II: Application 1 - Large increases in isoform resolution of human transferrin by use of dual simultaneous independent gradients of pH & acetonitrile on a mixed bed (anion exchange plus reversed phase) stationary phase.

PubMed

Tsonev, Latchezar I; Hirsh, Allen G

2016-10-14

We have previously described a liquid chromatographic (LC) method for uncoupling controlled, wide range pH gradients and simultaneous controlled gradients of a non-buffering solute on ion exchange resins (Hirsh and Tsonev, 2012) [1]. Here we report the application of this two dimensional LC technique to the problem of resolving Human Transferrin (HT) isoforms. This important iron transporting protein should theoretically occur in several thousand glycoforms, but only about a dozen have been reported. Using dual simultaneous independent gradients (DSIGs) of acetonitrile (ACN) and pH on a mixed bed stationary phase (SP) consisting of a mixture of an anion exchange resin and a reversed phase (RP) resin we partially resolve about 60 isoforms. These are likely to be partially refolded glycoforms generated by interaction of HT with the highly hydrophobic RP SP, as well as distinct folded glycoforms. Thus this study should have interesting implications for both glycoform separation and the study of protein folding. Copyright © 2016 Elsevier B.V. All rights reserved.

Targeted mitochondrial uncoupling beyond UCP1 - The fine line between death and metabolic health.

PubMed

Ost, Mario; Keipert, Susanne; Klaus, Susanne

2017-03-01

In the early 1930s, the chemical uncoupling agent 2,4-dinitrophenol (DNP) was promoted for the very first time as a powerful and effective weight loss pill but quickly withdrawn from the market due to its lack of tissue-selectivity with resulting dangerous side effects, including hyperthermia and death. Today, novel mitochondria- or tissue-targeted chemical uncouplers with higher safety and therapeutic values are under investigation in order to tackle obesity, diabetes and fatty liver disease. Moreover, in the past 20 years, transgenic mouse models were generated to understand the molecular and metabolic consequences of targeted uncoupling, expressing functional uncoupling protein 1 (UCP1) ectopically in white adipose tissue or skeletal muscle. Similar to the action of chemical mitochondrial uncouplers, UCP1 protein dissipates the proton gradient across the inner mitochondrial membrane, thus allowing maximum activity of the respiratory chain and compensatory increase in oxygen consumption, uncoupled from ATP synthesis. Consequently, targeted mitochondrial uncoupling in adipose tissue and skeletal muscle of UCP1-transgenic mice increased substrate metabolism and ameliorates obesity, hypertriglyceridemia and insulin resistance. Further, muscle-specific decrease in mitochondrial efficiency promotes a cell-autonomous and cell-non-autonomous adaptive metabolic remodeling with increased oxidative stress tolerance. This review provides an overview of novel chemical uncouplers as well as the metabolic consequences and adaptive processes of targeted mitochondrial uncoupling on metabolic health and survival. Copyright © 2016 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

Etomoxir-induced increase in UCP3 supports a role of uncoupling protein 3 as a mitochondrial fatty acid anion exporter.

PubMed

Schrauwen, Patrick; Hinderling, Vera; Hesselink, Matthijs K C; Schaart, Gert; Kornips, Esther; Saris, Wim H M; Westerterp-Plantenga, Margriet; Langhans, Wolfgang

2002-10-01

The physiological function of human uncoupling protein-3 is still unknown. Uncoupling protein-3 is increased during fasting and high-fat feeding. In these situations the availability of fatty acids to the mitochondria exceeds the capacity to metabolize fatty acids, suggesting a role for uncoupling protein-3 in handling of non-metabolizable fatty acids. To test the hypothesis that uncoupling protein-3 acts as a mitochondrial exporter of non-metabolizable fatty acids from the mitochondrial matrix, we gave human subjects Etomoxir (which blocks mitochondrial entry of fatty acids) or placebo in a cross-over design during a 36-h stay in a respiration chamber. Etomoxir inhibited 24-h fat oxidation and fat oxidation during exercise by approximately 14-19%. Surprisingly, uncoupling protein-3 content in human vastus lateralis muscle was markedly up-regulated within 36 h of Etomoxir administration. Up-regulation of uncoupling protein-3 was accompanied by lowered fasting blood glucose and increased translocation of glucose transporter-4. These data support the hypothesis that the physiological function of uncoupling protein-3 is to facilitate the outward transport of non-metabolizable fatty acids from the mitochondrial matrix and thus prevents mitochondria from the potential deleterious effects of high fatty acid levels. In addition our data show that up-regulation of uncoupling protein-3 can be beneficial in the treatment of type 2 diabetes.

High-frequency Born synthetic seismograms based on coupled normal modes

USGS Publications Warehouse

Pollitz, Fred F.

2011-01-01

High-frequency and full waveform synthetic seismograms on a 3-D laterally heterogeneous earth model are simulated using the theory of coupled normal modes. The set of coupled integral equations that describe the 3-D response are simplified into a set of uncoupled integral equations by using the Born approximation to calculate scattered wavefields and the pure-path approximation to modulate the phase of incident and scattered wavefields. This depends upon a decomposition of the aspherical structure into smooth and rough components. The uncoupled integral equations are discretized and solved in the frequency domain, and time domain results are obtained by inverse Fourier transform. Examples show the utility of the normal mode approach to synthesize the seismic wavefields resulting from interaction with a combination of rough and smooth structural heterogeneities. This approach is applied to an ∼4 Hz shallow crustal wave propagation around the site of the San Andreas Fault Observatory at Depth (SAFOD).

Computational methods for global/local analysis

NASA Technical Reports Server (NTRS)

Ransom, Jonathan B.; Mccleary, Susan L.; Aminpour, Mohammad A.; Knight, Norman F., Jr.

1992-01-01

Computational methods for global/local analysis of structures which include both uncoupled and coupled methods are described. In addition, global/local analysis methodology for automatic refinement of incompatible global and local finite element models is developed. Representative structural analysis problems are presented to demonstrate the global/local analysis methods.

Development and evaluation of the aerosol dynamics and gas phase chemistry model ADCHEM

NASA Astrophysics Data System (ADS)

Roldin, P.; Swietlicki, E.; Schurgers, G.; Arneth, A.; Lehtinen, K. E. J.; Boy, M.; Kulmala, M.

2011-06-01

The aim of this work was to develop a model suited for detailed studies of aerosol dynamics, gas and particle phase chemistry within urban plumes, from local scale (1 × 1 km2) to regional scale. This article describes and evaluates the trajectory model for Aerosol Dynamics, gas and particle phase CHEMistry and radiative transfer (ADCHEM). The model treats both vertical and horizontal dispersion perpendicular to an air mass trajectory (2-space dimensions). The Lagrangian approach enables a more detailed representation of the aerosol dynamics, gas and particle phase chemistry and a finer spatial and temporal resolution compared to that of available regional 3D-CTMs. These features make it among others well suited for urban plume studies. The aerosol dynamics model includes Brownian coagulation, dry deposition, wet deposition, in-cloud processing, condensation, evaporation, primary particle emissions and homogeneous nucleation. The organic mass partitioning was either modeled with a 2-dimensional volatility basis set (2D-VBS) or with the traditional two-product model approach. In ADCHEM these models consider the diffusion limited and particle size dependent condensation and evaporation of 110 and 40 different organic compounds respectively. The gas phase chemistry model calculates the gas phase concentrations of 61 different species, using 130 different chemical reactions. Daily isoprene and monoterpene emissions from European forests were simulated separately with the vegetation model LPJ-GUESS, and included as input to ADCHEM. ADCHEM was used to simulate the ageing of the urban plumes from the city of Malmö in southern Sweden (280 000 inhabitants). Several sensitivity tests were performed concerning the number of size bins, size structure method, aerosol dynamic processes, vertical and horizontal mixing, coupled or uncoupled condensation and the secondary organic aerosol formation. The simulations show that the full-stationary size structure gives accurate results with little numerical diffusion when more than 50 size bins are used between 1.5 and 2500 nm, while the moving-center method is preferable when only a few size bins are selected. The particle number size distribution in the center of the urban plume from Malmö was mainly affected by dry deposition, coagulation and vertical dilution. The modeled PM2.5 mass was dominated by organic material, nitrate, sulfate and ammonium. If the condensation of HNO3 and NH3 was treated as a coupled process (pH independent) the model gave lower nitrate PM2.5 mass than if considering uncoupled condensation. Although the time of ageing from that SOA precursors are emitted until condensable products are formed is substantially different with the 2D-VBS and two product model, the models gave similar total organic mass concentrations.

Supersonic flow of chemically reacting gas-particle mixtures. Volume 1: A theoretical analysis and development of the numerical solution

NASA Technical Reports Server (NTRS)

Penny, M. M.; Smith, S. D.; Anderson, P. G.; Sulyma, P. R.; Pearson, M. L.

1976-01-01

A numerical solution for chemically reacting supersonic gas-particle flows in rocket nozzles and exhaust plumes was described. The gas-particle flow solution is fully coupled in that the effects of particle drag and heat transfer between the gas and particle phases are treated. Gas and particles exchange momentum via the drag exerted on the gas by the particles. Energy is exchanged between the phases via heat transfer (convection and/or radiation). Thermochemistry calculations (chemical equilibrium, frozen or chemical kinetics) were shown to be uncoupled from the flow solution and, as such, can be solved separately. The solution to the set of governing equations is obtained by utilizing the method of characteristics. The equations cast in characteristic form are shown to be formally the same for ideal, frozen, chemical equilibrium and chemical non-equilibrium reacting gas mixtures. The particle distribution is represented in the numerical solution by a finite distribution of particle sizes.

Electromechanical Properties of Bone Tissue.

NASA Astrophysics Data System (ADS)

Regimbal, Raymond L.

Discrepancies between calculated and empirical properties of bone are thought to be due to a general lack of consideration for the extent and manner(s) with which bone components interact at the molecular level. For a bone component in physiological fluid or whenever two phases are in contact, there is a region between the bulk phases called the electrical double layer which is marked by a separation of electric charges. For the purpose of studying electrical double layer interactions, the method of particle microelectrophoresis was used to characterize bone and its major constituents on the basis of the net charge they bear when suspended in ionic media of physiological relevance. With the data presented as pH versus zeta (zeta ) potential, the figures reveal an isoelectric point (IEP) for bone mineral near pH 8.6, whereas intact and EDTA demineralized bone tissue both exhibit IEPs near pH 5.1. While these data demonstrate the potential for a significant degree of coulombic interaction between the bone mineral and organic constituent double layers, it was also observed that use of inorganic phosphate buffers, as a specific marker for bone mineral, resulted in (1) an immediate reversal, from positive to negative, of the bone mineral zeta potential (2) rendered the zeta potential of intact bone more negative in a manner linearly dependent on both time and temperature and (3) had no affect on demineralized bone (P < 0.01). In agreement with that shown in model protein-hydroxyapatite systems, it is suggested here that inorganic phosphate ions in solution compete with organic acid groups (e.g. carboxyl and phosphate of collagen, sialoprotein, ...) for positively charged sites on the bone mineral surface and effectively uncouple the bone mineral and organic phase double layers. Mechanically, this uncoupling is manifested as a loss of tissue rigidity when monitoring the midspan deflection of bone beams subject to constant load for a 3 day period. While it is thus demonstrated that the major inorganic and organic phases of bone are electromechanically coupled, a thermodynamic consideration of the data suggests that the nature of the bond is to preserve mineral and organic phase electroneutralities by participating in electrical double layer interactions. The results are discussed in terms of bone mechanical modeling, electrokinetic properties, aging, tissue-implant compatibility and the etiologies of bone pathologic conditions.

[Interaction of free fatty acids with mitochondria during uncoupling of oxidative phosphorylation].

PubMed

Samartsev, V N; Rybakova, S R; Dubinin, M V

2013-01-01

The activity of free saturated fatty acids (caprylic, capric, lauric, myristic, palmitic and stearic) as inducers and regulators of uncoupling of oxidative phosphorylation with participation of ADP/ATP antiporter, aspartate/glutamate antiporter and cyclosporin A-sensitive structure was investigated in experiments on rat liver mitochondria. It is established that at equal uncoupling activity of fatty acids the regulatory effect is minimal for caprylic acid and raised with increasing the hydrophobicity of fatty acids reaching the maximum value for stearic acid. There exists the linear dependence of the regulatory effect value of fatty acids on fatty acids content in the hydrophobic region of the inner membrane. The model that describes the interaction of fatty acids with the hydrophobic region of the mitochondrial inner membrane preserving functional activity of organelles is developed. It is established that if molecules of various fatty acids being in the hydrophobic region of the membrane are equally effective as uncoupling regulators, their specific uncoupling activity is different. Caprylic acid, a short-chain fatty acid, possesses the highest uncoupling activity. As the acyl chain length increases, the specific uncoupling activity of fatty acids reduces exponentially. Under these conditions components of the uncoupling activity sensitive to glutamate and carboxyatractylate and glutamate and insensitive to these reagents (but sensitive to cyclosporin A) change approximately equally.

Evaluation of three methods of different levels of complexity to represent the interactions between the Greenland ice sheet and the atmosphere at the century time scale.

NASA Astrophysics Data System (ADS)

Le clec'h, Sébastien; Fettweis, Xavier; Quiquet, Aurelien; Dumas, Christophe; Kageyama, Masa; Charbit, Sylvie; Ritz, Catherine

2017-04-01

Based on numerous studies showing implications of polar ice sheets on the climate system, the climate community recommended the development of methods to account for feedbacks between polar ice sheets and the other climate components. In this study we used three methods of different levels of complexity to represent the interactions between a Greenland ice sheet model (GRISLI) and a regional atmospheric model (MAR) under the RCP8.5 scenario. The simplest method, i.e. uncoupled, does not account for interactions between both models. In this method MAR computes varying atmospheric conditions using the same present-day observed Greenland ice sheet topography and extent. The outputs are then used to force GRISLI. The second method is a one-way coupling method in which the MAR outputs are corrected to account for topography changes before their transfer to GRISLI. The third method is a fully coupled method allowing the full representation of interactions between MAR and GRISLI. In this case, the ice sheet topography and its extent as seen by the atmospheric model is updated for each ice sheet model time step. The three methods are evaluated regarding the Greenland ice sheet response from 2000 to 2150. As expected, the uncoupled method shows a coastal thinning of the ice sheet due to a decreasing surface mass balance for coastal regions related to increased mean surface temperature. The one-way coupling and the full coupling methods tend to amplify the surface mass balance due to surface elevation feedback. The uncoupled method tends to underestimate the Greenland ice sheet volume reduction compared to both coupling methods over 150 years. This underestimation is of the same order of magnitude of the ice loss from the Greenland peripheral glaciers at the end of the 21st century. As for the uncoupled method, the thinning of the ice sheet occurs in coastal regions for both coupling methods. However compared to the one-way coupling method, the fully coupled method tends to increase the spatial variability of the surface mass balance changes through time. Our results also indicate that differences between the two coupling methods increase with time, which suggests that the choice of the method should depend on the timescale considered. Beyond century scale projections the fully coupled method is necessary in order to avoid underestimation of the ice sheet volume reduction, whilst the one-way method seems to be sufficient to represent the interactions between the atmosphere and the GrIS for projections by the end of the century.

Hypercholesterolemia-induced erectile dysfunction: endothelial nitric oxide synthase (eNOS) uncoupling in the mouse penis by NAD(P)H oxidase

PubMed Central

Musicki, Biljana; Liu, Tongyun; Lagoda, Gwen A.; Strong, Travis D.; Sezen, Sena F.; Johnson, Justin M.; Burnett, Arthur L.

2010-01-01

INTRODUCTION Hypercholesterolemia induces erectile dysfunction (ED) mostly by increasing oxidative stress and impairing endothelial function in the penis, but the mechanisms regulating reactive oxygen species (ROS) production in the penis are not understood. AIMS We evaluated whether hypercholesterolemia activates nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase in the penis, providing an initial source of ROS to induce endothelial nitric oxide synthase (eNOS) uncoupling and endothelial dysfunction resulting in ED. METHODS Low-density-lipoprotein receptor (LDLR)–null mice were fed Western diet for 4 weeks to induce early-stage hyperlipidemia. Wild type (WT) mice fed regular chow served as controls. Mice received NAD(P)H oxidase inhibitor apocynin (10 mM in drinking water) or vehicle. Erectile function was assessed in response to cavernous nerve electrical stimulation. Markers of endothelial function (phospho [P]-vasodilator-stimulated-protein [VASP]-Ser-239), oxidative stress (4-hydroxy-2-nonenal [HNE]), sources of ROS (eNOS uncoupling and NAD[P]H oxidase subunits p67phox, p47phox, and gp91phox), P-eNOS-Ser-1177, and eNOS were measured by Western blot in penes. MAIN OUTCOME MEASURES Molecular mechanisms of ROS generation and endothelial dysfunction in hypercholesterolemia-induced ED. RESULTS Erectile response was significantly (P<0.05) reduced in hypercholesterolemic LDLR-null mice compared to WT mice. Relative to WT mice, hypercholesterolemia increased (P<0.05) protein expressions of NAD(P)H oxidase subunits p67phox, p47phox and gp91phox, eNOS uncoupling, and 4-HNE-modified proteins, and reduced (P<0.05) P-VASP-Ser-239 expression in the penis. Apocynin treatment of LDLR-null mice preserved (P<0.05) maximal intracavernosal pressure, and reversed (P < 0.05) the abnormalities in protein expressions of gp67phox and gp47phox, 4-HNE, P-VASP-Ser-239, and eNOS uncoupling in the penis. Apocynin treatment of WT mice did not affect any of these parameters. Protein expressions of P-eNOS-Ser-1177 and total eNOS were unaffected by hypercholesterolemia. CONCLUSION Activated NAD(P)H oxidase in the penis is an initial source of oxidative stress resulting in eNOS uncoupling, thus providing a mechanism of eNOS uncoupling and endothelial dysfunction in hypercholesterolemia-induced ED. PMID:20626609

Sludge reduction by uncoupling metabolism: SBR tests with para-nitrophenol and a commercial uncoupler.

PubMed

Zuriaga-Agustí, E; Mendoza-Roca, J A; Bes-Piá, A; Alonso-Molina, J L; Amorós-Muñoz, I

2016-11-01

Nowadays cost reduction is a very important issue in wastewater treatment plants. One way, is to minimize the sludge production. Microorganisms break down the organic matter into inorganic compounds through catabolism. Uncoupling metabolism is a method which promote catabolism reactions instead of anabolism ones, where adenosine triphosphate synthesis is inhibited. In this work, the influence of the addition of para-nitrophenol and a commercial reagent to a sequencing batch reactor (SBR) on sludge production and process performance has been analyzed. Three laboratory SBRs were operated in parallel to compare the effect of the addition of both reagents with a control reactor. SBRs were fed with synthetic wastewater and were operated with the same conditions. Results showed that sludge production was slightly reduced for the tested para-nitrophenol concentrations (20 and 25 mg/L) and for a LODOred dose of 1 mL/day. Biological process performance was not influenced and high COD removals were achieved. Copyright © 2016 Elsevier Ltd. All rights reserved.

Endocrine regulation of uncoupling proteins and energy expenditure.

PubMed

Ricquier, D; Miroux, B; Larose, M; Cassard-Doulcier, A M; Bouillaud, F

2000-06-01

Regulatory thermogenesis occurs upon exposure to the cold or during food intake. Among a variety of mechanisms leading to heat production, uncoupling of respiration in brown adipocyte mitochondria appears to be a major contributor to resistance to the cold in rodents. This uncoupling mechanism is due to the activity of uncoupling protein-1 (UCP-1), a specific carrier present in the inner membrane of mitochondria. The recent identification of UCP-2 and UCP-3, two homologues of the brown fat UCP, suggested that respiration uncoupling could contribute to thermogenesis in most tissues. Activity and expression of the three UCP's are stimulated by several neuromediators and hormones such as noradrenaline, tri-iodothyronine and leptin.

Stability of the IMEX Methods, CNLF and BDF2-AB2, for Uncoupling Systems of Evolution Equations

DTIC Science & Technology

2011-02-01

Implicit-Explicit linear multistep methods, Tech. rep., Centrum Wiskunde and Informatica (CWI) (1996). [14] W. Hundsdorfer, J. Verwer, Numerical...component splitting for the Crank-Nicolson Leap- Frog integration method, Tech. rep., Centrum Wiskunde and Informatica (CWI) (2009). [23] J. Verwer

Endothermy in birds: underlying molecular mechanisms.

PubMed

Walter, Isabel; Seebacher, Frank

2009-08-01

Endothermy is significant in vertebrate evolution because it changes the relations between animals and their environment. How endothermy has evolved in archosaurs (birds, crocodiles and dinosaurs) is controversial especially because birds do not possess brown adipose tissue, the specialized endothermic tissue of mammals. Internal heat production is facilitated by increased oxidative metabolic capacity, accompanied by the uncoupling of aerobic metabolism from energy (ATP) production. Here we show that the transition from an ectothermic to an endothermic metabolic state in developing chicken embryos occurs by the interaction between increased basal ATP demand (Na(+)/K(+)-ATPase activity and gene expression), increased oxidative capacity and increased uncoupling of mitochondria; this process is controlled by thyroid hormone via its effect on PGC1alpha and adenine nucleotide translocase (ANT) gene expression. Mitochondria become more uncoupled during development, but unlike in mammals, avian uncoupling protein (avUCP) does not uncouple electron transport from oxidative phosphorylation and therefore plays no role in heat production. Instead, ANT is the principal uncoupling protein in birds. The relationship between oxidative capacity and uncoupling indicates that there is a continuum of phenotypes that fall between the extremes of selection for increased heat production and increased aerobic activity, whereas increased cellular ATP demand is a prerequisite for increased oxidative capacity.

Uncoupling protein-3 lowers reactive oxygen species production in isolated mitochondria

PubMed Central

Toime, Laurence J.; Brand, Martin D.

2010-01-01

Mitochondria are the major cellular producers of reactive oxygen species (ROS), and mitochondrial ROS production increases steeply with increased protonmotive force. The uncoupling proteins (UCP1, UCP2 and UCP3) and adenine nucleotide translocase induce proton leak in response to exogenously added fatty acids, superoxide or lipid peroxidation products. “Mild uncoupling” by these proteins may provide a negative feedback loop to decrease protonmotive force and attenuate ROS production. Using wild type and Ucp3−/− mice, we found that native UCP3 actively lowers the rate of ROS production in isolated energized skeletal muscle mitochondria, in the absence of exogenous activators. The estimated specific activity of UCP3 in lowering ROS production was 90 to 500 times higher than that of the adenine nucleotide translocase. The mild uncoupling hypothesis was tested by measuring whether the effect of UCP3 on ROS production could be mimicked by chemical uncoupling. A chemical uncoupler mimicked the effect of UCP3 at early time points after mitochondrial energization, in support of the mild uncoupling hypothesis. However, at later time points the uncoupler did not mimic UCP3, suggesting that UCP3 can also affect on ROS production through a membrane potential-independent mechanism. PMID:20493945

Visual information underpinning skilled anticipation: The effect of blur on a coupled and uncoupled in situ anticipatory response.

PubMed

Mann, David L; Abernethy, Bruce; Farrow, Damian

2010-07-01

Coupled interceptive actions are understood to be the result of neural processing-and visual information-which is distinct from that used for uncoupled perceptual responses. To examine the visual information used for action and perception, skilled cricket batters anticipated the direction of balls bowled toward them using a coupled movement (an interceptive action that preserved the natural coupling between perception and action) or an uncoupled (verbal) response, in each of four different visual blur conditions (plano, +1.00, +2.00, +3.00). Coupled responses were found to be better than uncoupled ones, with the blurring of vision found to result in different effects for the coupled and uncoupled response conditions. Low levels of visual blur did not affect coupled anticipation, a finding consistent with the comparatively poorer visual information on which online interceptive actions are proposed to rely. In contrast, some evidence was found to suggest that low levels of blur may enhance the uncoupled verbal perception of movement.

Proton motive force, energy recycling by end product excretion, and metabolic uncoupling during anaerobic growth of Pseudomonas mendocina.

PubMed Central

Verdoni, N; Aon, M A; Lebeault, J M; Thomas, D

1990-01-01

Batch cultures of Pseudomonas mendocina, grown in rich medium with glucose excess, showed metabolic differences dependent upon whether the growth conditions were aerobic or anaerobic, with or without added electron acceptor. Under anaerobic conditions in the absence of nitrate, P. mendocina reached the stationary phase of growth after 2 or 3 days, followed by a stationary phase of 4 to 5 days. Under these conditions, a mixed-type fermentative metabolism (formic, lactic, and acetic acids) appeared. A fivefold-higher specific rate of glucose consumption and eightfold-higher production of organic acids, compared with aerobic cultures, were shown by this microorganism growing anaerobically in the absence of exogenous electron acceptors. The gradients of organic acid produced by P. mendocina under these conditions reached a maximum (lactate, 180 mV; formate, 150 mV; acetate, 215 mV) between days 2 and 3 of culture. The proton motive force (delta p) decreased during growth from -254 to -71 mV. The intracellular pH remained alkaline during the culture, reaching a steady-state value of 7.9. The gradients of organic acids apparently contributed to the generation of a delta p, which, according to the Energy Recycling Model (P. A. M. Michels, J. P. J. Michels, J. Boonstra, and W. N. Konings, FEMS Microbiol. Lett. 5:357-364, 1979), would produce an average energy gain of 1 or 1.5 mol of ATP equivalents per mol of glucose consumed with H+/ATP stoichiometry of 3 or 2, respectively. Low YATP and Yglucose values were observed, suggesting that an uncoupled metabolism exists; i.e., ATP produced by catabolic processes is not directly used for biomass synthesis. This metabolic uncoupling could be induced at least in part by organic acids and the ATP wastage could be induced by a membrane-bound ATPase involved in intracellular pH regulation. PMID:2254245

49 CFR 215.125 - Defective uncoupling device.

Code of Federal Regulations, 2014 CFR

2014-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD FREIGHT CAR SAFETY STANDARDS Freight Car Components Draft System § 215.125 Defective uncoupling device. A railroad may not place or continue in service a car, if the car has an uncoupling device without sufficient vertical and lateral clearance to prevent— (a...

49 CFR 215.125 - Defective uncoupling device.

Code of Federal Regulations, 2011 CFR

2011-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD FREIGHT CAR SAFETY STANDARDS Freight Car Components Draft System § 215.125 Defective uncoupling device. A railroad may not place or continue in service a car, if the car has an uncoupling device without sufficient vertical and lateral clearance to prevent— (a...

49 CFR 215.125 - Defective uncoupling device.

Code of Federal Regulations, 2010 CFR

2010-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD FREIGHT CAR SAFETY STANDARDS Freight Car Components Draft System § 215.125 Defective uncoupling device. A railroad may not place or continue in service a car, if the car has an uncoupling device without sufficient vertical and lateral clearance to prevent— (a...

49 CFR 215.125 - Defective uncoupling device.

Code of Federal Regulations, 2013 CFR

2013-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD FREIGHT CAR SAFETY STANDARDS Freight Car Components Draft System § 215.125 Defective uncoupling device. A railroad may not place or continue in service a car, if the car has an uncoupling device without sufficient vertical and lateral clearance to prevent— (a...

49 CFR 215.125 - Defective uncoupling device.

Code of Federal Regulations, 2012 CFR

2012-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD FREIGHT CAR SAFETY STANDARDS Freight Car Components Draft System § 215.125 Defective uncoupling device. A railroad may not place or continue in service a car, if the car has an uncoupling device without sufficient vertical and lateral clearance to prevent— (a...

Impaired Adaptability of in Vivo Mitochondrial Energetics to Acute Oxidative Insult in Aged Skeletal Muscle

PubMed Central

Siegel, Michael P.; Wilbur, Tim; Mathis, Mark; Shankland, Eric; Trieu, Atlas; Harper, Mary-Ellen; Marcinek, David J.

2012-01-01

Periods of elevated reactive oxygen species (ROS) production are a normal part of mitochondrial physiology. However, little is known about age-related changes in the mitochondrial response to elevated ROS in vivo. Significantly, ROS-induced uncoupling of oxidative phosphorylation has received attention as a negative feedback mechanism to reduce mitochondrial superoxide production. Here we use a novel in vivo spectroscopy system to test the hypothesis that ROS-induced uncoupling is diminished in aged mitochondria. This system simultaneously acquires 31P magnetic resonance and near-infrared optical spectra to non-invasively measure phosphometabolite and O2 concentrations in mouse skeletal muscle. Using low dose paraquat to elevate intracellular ROS we assess in vivo mitochondrial function in young, middle aged, and old mice. Oxidative phosphorylation was uncoupled to the same degree in response to ROS at each age, but this uncoupling was associated with loss of phosphorylation capacity and total ATP in old mice only. Using mice lacking UCP3 we demonstrate that this in vivo uncoupling is independent of this putative uncoupler of skeletal muscle mitochondria. These data indicate that ROS-induced uncoupling persists throughout life, but that oxidative stress leads to mitochondrial deficits and loss of ATP in aged organisms that may contribute to impaired function and degeneration. PMID:22935551

UV Resonance Raman Elucidation of the Terminal and Internal Peptide Bond Conformations of Crystalline and Solution Oligoglycines.

PubMed

Bykov, Sergei V; Asher, Sanford A

2010-11-30

Spectroscopic investigations of macromolecules generally attempt to interpret the measured spectra in terms of the summed contributions of the different molecular fragments. This is the basis of the local mode approximation in vibrational spectroscopy. In the case of resonance Raman spectroscopy independent contributions of molecular fragments require both a local mode-like behavior and the uncoupled electronic transitions. Here we show that the deep UV resonance Raman spectra of aqueous solution phase oligoglycines show independent peptide bond molecular fragment contributions indicating that peptide bonds electronic transitions and vibrational modes are uncoupled. We utilize this result to separately determine the conformational distributions of the internal and penultimate peptide bonds of oligoglycines. Our data indicate that in aqueous solution the oligoglycine terminal residues populate conformations similar to those found in crystals (3(1)-helices and β-strands), but with a broader distribution, while the internal peptide bond conformations are centered around the 3(1)-helix Ramachandran angles.

High-frequency Born synthetic seismograms based on coupled normal modes

USGS Publications Warehouse

Pollitz, F.

2011-01-01

High-frequency and full waveform synthetic seismograms on a 3-D laterally heterogeneous earth model are simulated using the theory of coupled normal modes. The set of coupled integral equations that describe the 3-D response are simplified into a set of uncoupled integral equations by using the Born approximation to calculate scattered wavefields and the pure-path approximation to modulate the phase of incident and scattered wavefields. This depends upon a decomposition of the aspherical structure into smooth and rough components. The uncoupled integral equations are discretized and solved in the frequency domain, and time domain results are obtained by inverse Fourier transform. Examples show the utility of the normal mode approach to synthesize the seismic wavefields resulting from interaction with a combination of rough and smooth structural heterogeneities. This approach is applied to an ~4 Hz shallow crustal wave propagation around the site of the San Andreas Fault Observatory at Depth (SAFOD). ?? The Author Geophysical Journal International ?? 2011 RAS.

Thermal protection system gap analysis using a loosely coupled fluid-structural thermal numerical method

NASA Astrophysics Data System (ADS)

Huang, Jie; Li, Piao; Yao, Weixing

2018-05-01

A loosely coupled fluid-structural thermal numerical method is introduced for the thermal protection system (TPS) gap thermal control analysis in this paper. The aerodynamic heating and structural thermal are analyzed by computational fluid dynamics (CFD) and numerical heat transfer (NHT) methods respectively. An interpolation algorithm based on the control surface is adopted for the data exchanges on the coupled surface. In order to verify the analysis precision of the loosely coupled method, a circular tube example was analyzed, and the wall temperature agrees well with the test result. TPS gap thermal control performance was studied by the loosely coupled method successfully. The gap heat flux is mainly distributed in the small region at the top of the gap which is the high temperature region. Besides, TPS gap temperature and the power of the active cooling system (CCS) calculated by the traditional uncoupled method are higher than that calculated by the coupled method obviously. The reason is that the uncoupled method doesn't consider the coupled effect between the aerodynamic heating and structural thermal, however the coupled method considers it, so TPS gap thermal control performance can be analyzed more accurately by the coupled method.

Large enhancement of skeletal muscle cell glucose uptake and suppression of hepatocyte glucose-6-phosphatase activity by weak uncouplers of oxidative phosphorylation.

PubMed

Martineau, Louis C

2012-02-01

Perturbation of energy homeostasis in skeletal muscle and liver resulting from a transient inhibition of mitochondrial energy transduction can produce effects of relevance for the control of hyperglycemia through activation of the AMP-activated protein kinase, as exemplified by the antidiabetic drug metformin. The present study focuses on uncoupling of oxidative phosphorylation rather than its inhibition as a trigger for such effects. The reference weak uncoupler 2,4-dinitrophenol, fourteen naturally-occurring phenolic compounds identified as uncouplers in isolated rat liver mitochondria, and fourteen related compounds with little or no uncoupling activity were tested for enhancement of glucose uptake in differentiated C2C12 skeletal muscle cells following 18 h of treatment at 25-100 μM. A subset of compounds were tested for suppression of glucose-6-phosphatase (G6Pase) activity in H4IIE hepatocytes following 16 h at 12.5-25 μM. Metformin (400 μM) was used as a standard in both assays. Dinitrophenol and nine of eleven compounds that induced 50% or more uncoupling at 100 μM in isolated mitochondria enhanced basal glucose uptake by 53 to 269%; the effect of the 4'-hydroxychalcone butein was more than 6-fold that of metformin; negative control compounds increased uptake by no more than 25%. Dinitrophenol and four 4'-hydroxychalconoids also suppressed hepatocyte G6Pase as well as, or more effectively than metformin, whereas the unsubstituted parent compound chalcone, devoid of uncoupling activity, had no effect. Activities key to glycemic control can be induced by a wide range of weak uncouplers, including compounds free of difficult-to-metabolize groups typically associated with uncouplers. Uncoupling represents a valid and possibly more efficient alternative to inhibition for triggering cytoprotective effects of therapeutic relevance to insulin resistance in both muscle and liver. Identification of actives of natural origin and the insights into their structure-activity relationship reported herein may lead to alternatives to metformin. Copyright © 2011 Elsevier B.V. All rights reserved.

Reduced-Order Models for Acoustic Response Prediction

DTIC Science & Technology

2011-07-01

pressure on the surface of a flight vehicle skin can have complex amplitude and phase content. However, the pressure is often assumed to be a plane ...were used in the simulations. The input spectrum excited the first two symmetric bending modes of the beam . These two modes occurred at 79.0 Hz...the modal amplitude vector and  is a truncated set of uncoupled, mass normalized, mode shapes for the exterior acoustic domain. There are two

Uncoupling protein expression in skeletal muscle and adipose tissue in response to in vivo porcine somatotropin treatment

USDA-ARS?s Scientific Manuscript database

The uncoupling proteins are thought to be involved in waste heat production, reducing the energy efficiency of growth in animals. Previous studies have detected their presence in swine and their regulation by the endocrine system. This study attempted to determine whether the uncoupling proteins 2...

The mechanism of uncoupling by picrate in Escherichia coli K-12 membrane systems.

PubMed

Michels, M; Bakker, E P

1981-06-01

The mechanism of action of the uncoupler picrate on intact cells and everted membrane vesicles of Escherichia coli K-12 was investigated. Like in mitochondria [Hanstein, W. G. and Hatefi, Y. (1974) Proc. Natl Acad. Sci. USA, 71, 288-292], it was observed that picrate uncoupled energy-linked functions only in everted, but not in intact membrane systems. In the vesicles picrate also decreased the magnitude of the transmembrane proton-motive force at concentrations similar to those at which it caused uncoupling. Experiments with 14C-labelled picrate showed that this compound bound both to deenergized intact cells and everted vesicles. However, upon energization of the membrane, picrate was extruded from the intact cell and taken up to a larger extent by the vesicles. These energy-dependent changes in picrate uptake correlated with the magnitude of the transmembrane electrical potential, delta psi. It is therefore proposed that picrate is a permeant uncoupler, that delta psi is the driving force for picrate movement across biological membranes, and that the uncoupling activity of picrate in everted membrane systems is due to its protonophoric action.

Development of an integrated BEM approach for hot fluid structure interaction

NASA Technical Reports Server (NTRS)

Dargush, Gary F.; Banerjee, Prasanta K.; Dunn, Michael G.

1988-01-01

Significant progress was made toward the goal of developing a general purpose boundary element method for hot fluid-structure interaction. For the solid phase, a boundary-only formulation was developed and implemented for uncoupled transient thermoelasticity in two dimensions. The elimination of volume discretization not only drastically reduces required modeling effort, but also permits unconstrained variation of the through-the-thickness temperature distribution. Meanwhile, for the fluids, fundamental solutions were derived for transient incompressible and compressible flow in the absence of the convective terms. Boundary element formulations were developed and described. For the incompressible case, the necessary kernal functions, under transient and steady-state conditions, were derived and fully implemented into a general purpose, multi-region boundary element code. Several examples were examined to study the suitability and convergence characteristics of the various algorithms.

Gap junction communications influence upon fibroblast synthesis of Type I collagen and fibronectin.

PubMed

Ehrlich, H Paul; Sun, Bonnie; Saggers, Gregory C; Kromath, Fatuma

2006-07-01

In rats polyvinyl alcohol sponge subcutaneous implants treated with gap junctional intercellular communications (GJIC) uncouplers showed reduced deposition of connective tissue. Do uncouplers inhibit the synthesis and deposition of a new connective tissue by fibroblasts? Confluent human dermal fibroblasts in serum-free medium received either endosulfan or oleamide, GJIC uncouplers. Collected media were subjected to Dot Blot analysis for native Type I collagen and fibronectin. Uncoupler-treated fibroblasts released less Type I collagen, while there was no change in fibronectin release. Collagen synthesis was restored to normal, when the uncouplers were removed, showing that these uncouplers were reversible and not toxic to cells. Northern blot analysis revealed procollagen alpha1 (I) mRNA was minimally affected by endosulfan. Oleamide-treated 17-day chick embryo calvaria explants were incubated with Type I collagen antibody, frozen, cryosectioned, and then subjected to rhodamine (Rh) tagged anti-mouse-IgG antibody, to detect newly deposited Type I collagen. Fluorescent antibody-collagen complexes were localized on the periphery of cells in control calvaria, but absent around cells in oleamide-treated calvaria. GJIC optimize collagen synthesis but not fibronectin synthesis. The lack of connective tissue deposited in granulation tissues treated with uncouplers appears related to the inhibition of collagen synthesis. These findings suggest that altering GJIC might control collagen deposition in scarring. 2006 Wiley-Liss, Inc.

Mitochondrial uncoupling agents antagonize rotenone actions in rat substantia nigra dopamine neurons.

PubMed

Wu, Yan-Na; Munhall, Adam C; Johnson, Steven W

2011-06-13

Mild uncoupling of oxidative phosphorylation has been reported to reduce generation of reactive oxygen species (ROS) and therefore may be neuroprotective. We reported previously that the mitochondrial poison rotenone enhanced currents evoked by N-methyl-D-aspartate (NMDA) by a ROS-dependent mechanism in rat midbrain dopamine neurons. Thus, rotenone, which produces a model of Parkinson's disease in rodents, may increase the risk of dopamine neuron excitotoxicity. The purpose of this study was to test the hypothesis that oxidative phosphorylation uncoupling agents would antagonize the effect of rotenone on NMDA current. We used patch pipettes to record whole-cell currents under voltage-clamp (-60 mV) in substantia nigra dopamine neurons in slices of rat brain. Rotenone, NMDA and uncoupling agents were added to the brain slice superfusate. Inward currents evoked by NMDA (30 μM) more than doubled in amplitude after slices were superfused for 30 min with 100 nM rotenone. Continuous superfusion with the uncoupling agent carbonyl cyanide-p-trifluoromethoxy-phenylhydrazone (1-3 nM) or 2,4-dinitrophenol (100 nM) significantly antagonized and delayed the ability of rotenone to potentiate NMDA currents. Coenzyme Q₁₀ (1-10 nM), which has been reported to facilitate uncoupling protein activity, also antagonized this action of rotenone. These results suggest that mild uncoupling of oxidative phosphorylation may protect dopamine neurons against injury from mitochondrial poisons such as rotenone. Published by Elsevier B.V.

Impaired adaptability of in vivo mitochondrial energetics to acute oxidative insult in aged skeletal muscle.

PubMed

Siegel, Michael P; Wilbur, Tim; Mathis, Mark; Shankland, Eric G; Trieu, Atlas; Harper, Mary-Ellen; Marcinek, David J

2012-01-01

Periods of elevated reactive oxygen species (ROS) production are a normal part of mitochondrial physiology. However, little is known about age-related changes in the mitochondrial response to elevated ROS in vivo. Significantly, ROS-induced uncoupling of oxidative phosphorylation has received attention as a negative feedback mechanism to reduce mitochondrial superoxide production. Here we use a novel in vivo spectroscopy system to test the hypothesis that ROS-induced uncoupling is diminished in aged mitochondria. This system simultaneously acquires (31)P magnetic resonance and near-infrared optical spectra to non-invasively measure phosphometabolite and O(2) concentrations in mouse skeletal muscle. Using low dose paraquat to elevate intracellular ROS we assess in vivo mitochondrial function in young, middle aged, and old mice. Oxidative phosphorylation was uncoupled to the same degree in response to ROS at each age, but this uncoupling was associated with loss of phosphorylation capacity and total ATP in old mice only. Using mice lacking UCP3 we demonstrate that this in vivo uncoupling is independent of this putative uncoupler of skeletal muscle mitochondria. These data indicate that ROS-induced uncoupling persists throughout life, but that oxidative stress leads to mitochondrial deficits and loss of ATP in aged organisms that may contribute to impaired function and degeneration. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Active control of panel vibrations induced by boundary-layer flow

NASA Technical Reports Server (NTRS)

Chow, Pao-Liu

1991-01-01

Some problems in active control of panel vibration excited by a boundary layer flow over a flat plate are studied. In the first phase of the study, the optimal control problem of vibrating elastic panel induced by a fluid dynamical loading was studied. For a simply supported rectangular plate, the vibration control problem can be analyzed by a modal analysis. The control objective is to minimize the total cost functional, which is the sum of a vibrational energy and the control cost. By means of the modal expansion, the dynamical equation for the plate and the cost functional are reduced to a system of ordinary differential equations and the cost functions for the modes. For the linear elastic plate, the modes become uncoupled. The control of each modal amplitude reduces to the so-called linear regulator problem in control theory. Such problems can then be solved by the method of adjoint state. The optimality system of equations was solved numerically by a shooting method. The results are summarized.

Uncoupling of sgRNAs from their associated barcodes during PCR amplification of combinatorial CRISPR screens

PubMed Central

2018-01-01

Many implementations of pooled screens in mammalian cells rely on linking an element of interest to a barcode, with the latter subsequently quantitated by next generation sequencing. However, substantial uncoupling between these paired elements during lentiviral production has been reported, especially as the distance between elements increases. We detail that PCR amplification is another major source of uncoupling, and becomes more pronounced with increased amounts of DNA template molecules and PCR cycles. To lessen uncoupling in systems that use paired elements for detection, we recommend minimizing the distance between elements, using low and equal template DNA inputs for plasmid and genomic DNA during PCR, and minimizing the number of PCR cycles. We also present a vector design for conducting combinatorial CRISPR screens that enables accurate barcode-based detection with a single short sequencing read and minimal uncoupling. PMID:29799876

Bispectral analysis: comparison of two windowing functions

NASA Astrophysics Data System (ADS)

Silvagni, D.; Djerroud, C.; Réveillé, T.; Gravier, E.

2018-02-01

Amongst all the normalized forms of bispectrum, the bicoherence is shown to be a very useful diagnostic tool in experimental studies of nonlinear wave interactions in plasma, as it measures the fraction of wave power due to the quadratic wave coupling in a self-excited fluctuation spectrum [1, 2]. In order to avoid spectral leakage, the application of a windowing function is needed during the bicoherence computation. Spectral leakage from statistically dependent components are of crucial importance in the discrimination between coupled and uncoupled modes, as they will introduce in the bicoherence spectrum phase-coupled modes which in reality do not exist. Therefore, the windowing function plays a key role in the bicoherence estimation. In this paper, two windowing methods are compared: the multiplication of the initial signal by the Hanning function and the subtraction of the straight line which links the two extremities of the signal. The influence of these two windowing methods on both the power spectrum and the bicoherence spectrum is showed. Although both methods give precise results, the Hanning function appears to be the more suitable window.

Low concentration of uncouplers of oxidative phosphorylation decreases the TNF-induced endothelial permeability and lethality in mice.

PubMed

Zakharova, Vlada V; Pletjushkina, Olga Yu; Galkin, Ivan I; Zinovkin, Roman A; Chernyak, Boris V; Krysko, Dmitri V; Bachert, Claus; Krysko, Olga; Skulachev, Vladimir P; Popova, Ekaterina N

2017-04-01

Mitochondrial dysfunctions occur in many diseases linked to the systemic inflammatory response syndrome (SIRS). Mild uncoupling of oxidative phosphorylation is known to rescue model animals from pathologies related to mitochondrial dysfunctions and overproduction of reactive oxygen species (ROS). To study the potential of SIRS therapy by uncoupling, we tested protonophore dinitrophenol (DNP) and a free fatty acid (FFA) anion carrier, lipophilic cation dodecyltriphenylphosphonium (C 12 TPP) in mice and in vitro models of SIRS. DNP and C 12 TPP prevented the body temperature drop and lethality in mice injected with high doses of a SIRS inducer, tumor necrosis factor (TNF). The mitochondria-targeted antioxidant plastoquinonyl decyltriphenylphosphonium (SkQ1) which also catalyzes FFA-dependent uncoupling revealed similar protective effects and downregulated expression of the NFκB-regulated genes (VCAM1, ICAM1, MCP1, and IL-6) involved in the inflammatory response of endothelium in aortas of the TNF-treated mice. In vitro mild uncoupling rescued from TNF-induced endothelial permeability, disassembly of cell contacts and VE-cadherin cleavage by the matrix metalloprotease 9 (ММР9). The uncouplers prevented TNF-induced expression of MMP9 via inhibition of NFκB signaling. Water-soluble antioxidant Trolox also prevented TNF-induced activation and permeability of endothelium in vitro via inhibition of NFκB signaling, suggesting that the protective action of the uncouplers is linked to their antioxidant potential. Copyright © 2017 Elsevier B.V. All rights reserved.

Partial uncoupling of oxidative phosphorylation induces premature senescence in human fibroblasts and yeast mother cells.

PubMed

Stöckl, Petra; Zankl, Christina; Hütter, Eveline; Unterluggauer, Hermann; Laun, Peter; Heeren, Gino; Bogengruber, Edith; Herndler-Brandstetter, Dietmar; Breitenbach, Michael; Jansen-Dürr, Pidder

2007-09-15

The mitochondrial theory of aging predicts that functional alterations in mitochondria leading to reactive oxygen species (ROS) production contribute to the aging process in most if not all species. Using cellular senescence as a model for human aging, we have recently reported partial uncoupling of the respiratory chain in senescent human fibroblasts. In the present communication, we address a potential cause-effect relationship between impaired mitochondrial coupling and premature senescence. Chronic exposure of human fibroblasts to the chemical uncoupler carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP) led to a temporary, reversible uncoupling of oxidative phosphorylation. FCCP inhibited cell proliferation in a dose-dependent manner, and a significant proportion of the cells entered premature senescence within 12 days. Unexpectedly, chronic exposure of cells to FCCP led to a significant increase in ROS production, and the inhibitory effect of FCCP on cell proliferation was eliminated by the antioxidant N-acetyl-cysteine. However, antioxidant treatment did not prevent premature senescence, suggesting that a reduction in the level of oxidative phosphorylation contributes to phenotypical changes characteristic of senescent human fibroblasts. To assess whether this mechanism might be conserved in evolution, the influence of mitochondrial uncoupling on replicative life span of yeast cells was also addressed. Similar to our findings in human fibroblasts, partial uncoupling of oxidative phsophorylation in yeast cells led to a substantial decrease in the mother-cell-specific life span and a concomitant incrase in ROS, indicating that life span shortening by mild mitochondrial uncoupling may represent a "public" mechanism of aging.

Transient response for interaction of two dynamic bodies

NASA Technical Reports Server (NTRS)

Prabhakar, A.; Palermo, L. G.

1987-01-01

During the launch sequence of any space vehicle complicated boundary interactions occur between the vehicle and the launch stand. At the start of the sequence large forces exist between the two; contact is then broken in a short but finite time which depends on the release mechanism. The resulting vehicle response produces loads which are very high and often form the design case. It is known that the treatment of the launch pad as a second dynamic body is significant for an accurate prediction of launch response. A technique was developed for obtaining loads generated by the launch transient with the effect of pad dynamics included. The method solves uncoupled vehicle and pad equations of motion. The use of uncoupled models allows the simulation of vehicle launch in a single computer run. Modal formulation allows a closed-form solution to be written, eliminating any need for a numerical integration algorithm. When the vehicle is on the pad the uncoupled pad and vehicle equations have to be modified to account for the constraints they impose on each other. This necessitates the use of an iterative procedure to converge to a solution, using Lagrange multipliers to apply the required constraints. As the vehicle lifts off the pad the coupling between the vehicle and the pad is eliminated point by point until the vehicle flies free. Results obtained by this method were shown to be in good agreement with observed loads and other analysis methods. The resulting computer program is general, and was used without modification to solve a variety of contact problems.

Complete nucleotide and derived amino acid sequence of cDNA encoding the mitochondrial uncoupling protein of rat brown adipose tissue: lack of a mitochondrial targeting presequence.

PubMed Central

Ridley, R G; Patel, H V; Gerber, G E; Morton, R C; Freeman, K B

1986-01-01

A cDNA clone spanning the entire amino acid sequence of the nuclear-encoded uncoupling protein of rat brown adipose tissue mitochondria has been isolated and sequenced. With the exception of the N-terminal methionine the deduced N-terminus of the newly synthesized uncoupling protein is identical to the N-terminal 30 amino acids of the native uncoupling protein as determined by protein sequencing. This proves that the protein contains no N-terminal mitochondrial targeting prepiece and that a targeting region must reside within the amino acid sequence of the mature protein. Images PMID:3012461

Hydroxynonenal and uncoupling proteins: a model for protection against oxidative damage.

PubMed

Echtay, Karim S; Pakay, Julian L; Esteves, Telma C; Brand, Martin D

2005-01-01

In this mini review we summarize recent studies from our laboratory that show the involvement of superoxide and the lipid peroxidation product 4-hydroxynonenal in the regulation of mitochondrial uncoupling. Superoxide produced during mitochondrial respiration is a major cause of the cellular oxidative damage that may underlie degenerative diseases and ageing. Superoxide production is very sensitive to the magnitude of the mitochondrial protonmotive force, so can be strongly decreased by mild uncoupling. Superoxide is able to give rise to other reactive oxygen species, which elicit deleterious effects primarily by oxidizing intracellular components, including lipids, DNA and proteins. Superoxide-induced lipid peroxidation leads to the production of reactive aldehydes, including 4-hydroxynonenal. These aldehydic lipid peroxidation products are in turn able to modify proteins such as mitochondrial uncoupling proteins and the adenine nucleotide translocase, converting them into active proton transporters. This activation induces mild uncoupling and so diminishes mitochondrial superoxide production, hence protecting against disease and oxidative damage at the expense of energy production.

eNOS-uncoupling in age-related erectile dysfunction

PubMed Central

Johnson, JM; Bivalacqua, TJ; Lagoda, GA; Burnett, AL; Musicki, B

2011-01-01

Aging is associated with ED. Although age-related ED is attributed largely to increased oxidative stress and endothelial dysfunction in the penis, the molecular mechanisms underlying this effect are not fully defined. We evaluated whether endothelial nitric oxide synthase (eNOS) uncoupling in the aged rat penis is a contributing mechanism. Correlatively, we evaluated the effect of replacement with eNOS cofactor tetrahydrobiopterin (BH4) on erectile function in the aged rats. Male Fischer 344 ‘young’ (4-month-old) and ‘aged’ (19-month-old) rats were treated with a BH4 precursor sepiapterin (10 mg/kg intraperitoneally) or vehicle for 4 days. After 1-day washout, erectile function was assessed in response to electrical stimulation of the cavernous nerve. Endothelial dysfunction (eNOS uncoupling) and oxidative stress (thiobarbituric acid reactive substances, TBARS) were measured by conducting western blot in penes samples. Erectile response was significantly reduced in aged rats, whereas eNOS uncoupling and TBARS production were significantly increased in the aged rat penis compared with young rats. Sepiapterin significantly improved erectile response in aged rats and prevented increase in TBARS production, but did not affect eNOS uncoupling in the penis of aged rats. These findings suggest that aging induces eNOS uncoupling in the penis, resulting in increased oxidative stress and ED. PMID:21289638

Physiological uncoupling of mitochondrial oxidative phosphorylation. Studies in different yeast species.

PubMed

Guerrero-Castillo, Sergio; Araiza-Olivera, Daniela; Cabrera-Orefice, Alfredo; Espinasa-Jaramillo, Juan; Gutiérrez-Aguilar, Manuel; Luévano-Martínez, Luís A; Zepeda-Bastida, Armando; Uribe-Carvajal, Salvador

2011-06-01

Under non-phosphorylating conditions a high proton transmembrane gradient inhibits the rate of oxygen consumption mediated by the mitochondrial respiratory chain (state IV). Slow electron transit leads to production of reactive oxygen species (ROS) capable of participating in deleterious side reactions. In order to avoid overproducing ROS, mitochondria maintain a high rate of O(2) consumption by activating different exquisitely controlled uncoupling pathways. Different yeast species possess one or more uncoupling systems that work through one of two possible mechanisms: i) Proton sinks and ii) Non-pumping redox enzymes. Proton sinks are exemplified by mitochondrial unspecific channels (MUC) and by uncoupling proteins (UCP). Saccharomyces. cerevisiae and Debaryomyces hansenii express highly regulated MUCs. Also, a UCP was described in Yarrowia lipolytica which promotes uncoupled O(2) consumption. Non-pumping alternative oxido-reductases may substitute for a pump, as in S. cerevisiae or may coexist with a complete set of pumps as in the branched respiratory chains from Y. lipolytica or D. hansenii. In addition, pumps may suffer intrinsic uncoupling (slipping). Promising models for study are unicellular parasites which can turn off their aerobic metabolism completely. The variety of energy dissipating systems in eukaryote species is probably designed to control ROS production in the different environments where each species lives.

Catalytic Activity of the Anaerobic Tyrosine Lyase Required for Thiamine Biosynthesis in Escherichia coli*

PubMed Central

Challand, Martin R.; Martins, Filipa T.; Roach, Peter L.

2010-01-01

Thiazole synthase in Escherichia coli is an αβ heterodimer of ThiG and ThiH. ThiH is a tyrosine lyase that cleaves the Cα–Cβ bond of tyrosine, generating p-cresol as a by-product, to form dehydroglycine. This reactive intermediate acts as one of three substrates for the thiazole cyclization reaction catalyzed by ThiG. ThiH is a radical S-adenosylmethionine (AdoMet) enzyme that utilizes a [4Fe-4S]+ cluster to reductively cleave AdoMet, forming methionine and a 5′-deoxyadenosyl radical. Analysis of the time-dependent formation of the reaction products 5′-deoxyadenosine (DOA) and p-cresol has demonstrated catalytic behavior of the tyrosine lyase. The kinetics of product formation showed a pre-steady state burst phase, and the involvement of DOA in product inhibition was identified by the addition of 5′-methylthioadenosine/S-adenosylhomocysteine nucleosidase to activity assays. This hydrolyzed the DOA and changed the rate-determining step but, in addition, substantially increased the uncoupled turnover of AdoMet. Addition of glyoxylate and ammonium inhibited the tyrosine cleavage reaction, but the reductive cleavage of AdoMet continued in an uncoupled manner. Tyrosine analogues were incubated with ThiGH, which showed a strong preference for phenolic substrates. 4-Hydroxyphenylpropionic acid analogues allowed uncoupled AdoMet cleavage but did not result in further reaction (Cα–Cβ bond cleavage). The results of the substrate analogue studies and the product inhibition can be explained by a mechanistic hypothesis involving two reaction pathways, a product-forming pathway and a futile cycle. PMID:19923213

The complementary and divergent roles of uncoupling proteins 1 and 3 in thermoregulation

PubMed Central

Riley, Christopher L.; Dao, Christine; Kenaston, M. Alexander; Muto, Luigina; Kohno, Shohei; Nowinski, Sara M.; Solmonson, Ashley D.; Pfeiffer, Matthew; Sack, Michael N.; Lu, Zhongping; Fiermonte, Giuseppe; Sprague, Jon E.

2016-01-01

Key points Both uncoupling protein 1 (UCP1) and UCP3 are important for mammalian thermoregulation.UCP1 and UCP3 in brown adipose tissue mediate early and late phases of sympathomimetic thermogenesis, respectively.Lipopolysaccharide thermogenesis requires skeletal muscle UCP3 but not UCP1.Acute noradrenaline‐induced hyperthermia requires UCP1 but not UCP3.Loss of both UCP1 and UCP3 accelerate the loss of body temperature compared to UCP1KO alone during acute cold exposure. Abstract Uncoupling protein 1 (UCP1) is the established mediator of brown adipose tissue‐dependent thermogenesis. In contrast, the role of UCP3, expressed in both skeletal muscle and brown adipose tissue, in thermoregulatory physiology is less well understood. Here, we show that mice lacking UCP3 (UCP3KO) have impaired sympathomimetic (methamphetamine) and completely abrogated lipopolysaccharide (LPS) thermogenesis, but a normal response to noradrenaline. By comparison, UCP1 knockout (UCP1KO) mice exhibit blunted methamphetamine and fully inhibited noradrenaline thermogenesis, but an increased febrile response to LPS. We further establish that mice lacking both UCP1 and 3 (UCPDK) fail to show methamphetamine‐induced hyperthermia, and have a markedly accelerated loss of body temperature and survival after cold exposure compared to UCP1KO mice. Finally, we show that skeletal muscle‐specific human UCP3 expression is able to significantly rescue LPS, but not sympathomimetic thermogenesis blunted in UCP3KO mice. These studies identify UCP3 as an important mediator of physiological thermogenesis and support a renewed focus on targeting UCP3 in metabolic physiology. PMID:27647490

UCP1, the mitochondrial uncoupling protein of brown adipocyte: A personal contribution and a historical perspective.

PubMed

Ricquier, Daniel

2017-03-01

The present text summarizes what was my contribution, starting in 1975, to the research on the uncoupling protein 1 (UCP1), the mitochondrial uncoupler of brown adipocytes. The research on UCP1 aimed at identifying the mechanisms of heat production by brown adipocytes that occurs in mammals either at birth or during cold exposure and arousal in hibernators. With others and in particular Dr. David Nicholls, I participated in the first experiments that contributed to the identification of UCP1. Important steps were the obtention of UCP1 antibodies followed with my main collaborator and friend Frédéric Bouillaud with the initial cloning of the UCP1 cDNA and gene from rats and humans. These molecular tools were then used not only to analyse UCP1 uncoupling activity and to investigate the effects of mutagenesis on the uncoupling function of this protein, but also to decipher the transcriptional regulation of the UCP1 gene. In addition to experiments carried out in rodents, we could identify UCP1 and thermogenic brown adipocytes in humans. A more recent outcome of our research on this uncoupling protein was the identification of a second isoform of UCP, that we named UCP2, and of several UCP homologues in mammals, chicken and plants. UCP1 is certainly a unique mitochondrial transporter able to uncouple respiration from ADP phosphorylation in mitochondria. The discovery of this protein has opened new avenues for studying energy expenditure in relation to overweight, obesity and related pathologies. Copyright © 2016. Published by Elsevier B.V.

Alkyl-substituted phenylamino derivatives of 7-nitrobenz-2-oxa-1,3-diazole as uncouplers of oxidative phosphorylation and antibacterial agents: involvement of membrane proteins in the uncoupling action.

PubMed

Antonenko, Yuri N; Denisov, Stepan S; Khailova, Ljudmila S; Nazarov, Pavel A; Rokitskaya, Tatyana; Tashlitsky, Vadim N; Firsov, Alexander M; Korshunova, Galina A; Kotova, Elena A

2017-03-01

In search for new effective uncouplers of oxidative phosphorylation, we studied 4-aryl amino derivatives of a fluorescent group 7-nitrobenz-2-oxa-1,3-diazol (NBD). In our recent work (Denisov et al., Bioelectrochemistry, 2014), NBD-conjugated alkyl amines (NBD-C n ) were shown to exhibit uncoupling activity. It was concluded that despite a pK a value being about 10, the expected hindering of the uncoupling activity could be overcome by insertion of an alkyl chain. There is evidence in the literature that the introduction of an aryl substituent in the 4-amino NBD group shifts the pK a to neutral values. Here we report the data on the properties of a number of 4-arylamino derivatives of NBD, namely, alkylphenyl-amino-NBD (C n -phenyl-NBD) with varying alkyl chain C n . By measuring the electrical current across planar bilayer lipid membrane, the protonophoric activity of C n -phenyl-NBD at neutral pH grew monotonously from C 1 - to C 6 -phenyl-NBD. All of these compounds increased the respiration rate and reduced the membrane potential of isolated rat liver mitochondria. Importantly, the uncoupling action of C 6 - and C 4 -phenyl-NBD was partially reversed by glutamate, diethyl pyrocarbonate (DEPC), 6-ketocholestanol, and carboxyatractyloside, thus pointing to the involvement of membrane proteins in the uncoupling activity of C n -phenyl-NBD in mitochondria. The pronounced recoupling effect of DEPC, an inhibitor of an aspartate-glutamate carrier (AGC), and that of its substrates for the first time highlighted AGC participation in the action of potent uncouplers on mitochondria. C 6 -phenyl-NBD produced strong antimicrobial effect on Bacillus subtilis, which manifested itself in cell membrane depolarization and suppression of bacterial growth at submicromolar concentrations. Copyright © 2016 Elsevier B.V. All rights reserved.

Dissociation Between Brown Adipose Tissue 18F-FDG Uptake and Thermogenesis in Uncoupling Protein 1-Deficient Mice.

PubMed

Hankir, Mohammed K; Kranz, Mathias; Keipert, Susanne; Weiner, Juliane; Andreasen, Sille G; Kern, Matthias; Patt, Marianne; Klöting, Nora; Heiker, John T; Brust, Peter; Hesse, Swen; Jastroch, Martin; Fenske, Wiebke K

2017-07-01

18 F-FDG PET imaging is routinely used to investigate brown adipose tissue (BAT) thermogenesis, which requires mitochondrial uncoupling protein 1 (UCP1). It remains uncertain, however, whether BAT 18 F-FDG uptake is a reliable surrogate measure of UCP1-mediated heat production. Methods: UCP1 knockout (KO) and wild-type (WT) mice housed at thermoneutrality were treated with the selective β3 adrenergic receptor agonist CL 316, 243 and underwent metabolic cage, infrared thermal imaging and 18 F-FDG PET/MRI experiments. Primary brown adipocytes were additionally examined for their bioenergetics by extracellular flux analysis as well as their uptake of 2-deoxy- 3 H-glucose. Results: In response to CL 316, 243 treatments, oxygen consumption, and BAT thermogenesis were diminished in UCP1 KO mice, but BAT 18 F-FDG uptake was fully retained. Isolated UCP1 KO brown adipocytes exhibited defective induction of uncoupled respiration whereas their glycolytic flux and 2-deoxy- 3 H-glucose uptake rates were largely unaffected. Conclusion: Adrenergic stimulation can increase BAT 18 F-FDG uptake independently of UCP1 thermogenic function. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

Uncoupling Protein 2 and Metabolic Diseases

PubMed Central

Sreedhar, Annapoorna; Zhao, Yunfeng

2017-01-01

Mitochondria are fascinating organelles involved in various cellular-metabolic activities that are integral for mammalian development. Although they perform diverse, yet interconnected functions, mitochondria are remarkably regulated by complex signaling networks. Therefore, it is not surprising that mitochondrial dysfunction is involved in plethora of diseases, including neurodegenerative and metabolic disorders. One of the many factors that lead to mitochondrial-associated metabolic diseases is the uncoupling protein-2, a family of mitochondrial anion proteins present in the inner mitochondrial membrane. Since their discovery, uncoupling proteins have attracted considerable attention due to their involvement in mitochondrial-mediated oxidative stress and energy metabolism. This review attempts to provide a summary of recent developments in the field of uncoupling protein 2 relating to mitochondrial associated metabolic diseases. PMID:28351676

UCP4C mediates uncoupled respiration in larvae of Drosophila melanogaster.

PubMed

Da-Ré, Caterina; De Pittà, Cristiano; Zordan, Mauro A; Teza, Giordano; Nestola, Fabrizio; Zeviani, Massimo; Costa, Rodolfo; Bernardi, Paolo

2014-05-01

Larvae of Drosophila melanogaster reared at 23°C and switched to 14°C for 1 h are 0.5°C warmer than the surrounding medium. In keeping with dissipation of energy, respiration of Drosophila melanogaster larvae cannot be decreased by the F-ATPase inhibitor oligomycin or stimulated by protonophore. Silencing of Ucp4C conferred sensitivity of respiration to oligomycin and uncoupler, and prevented larva-to-adult progression at 15°C but not 23°C. Uncoupled respiration of larval mitochondria required palmitate, was dependent on Ucp4C and was inhibited by guanosine diphosphate. UCP4C is required for development through the prepupal stages at low temperatures and may be an uncoupling protein.

Numerical Study of Rarefied Hypersonic Flow Interacting with a Continuum Jet. Degree awarded by Pennsylvania State Univ., Aug. 1999

NASA Technical Reports Server (NTRS)

Glass, Christopher E.

2000-01-01

An uncoupled Computational Fluid Dynamics-Direct Simulation Monte Carlo (CFD-DSMC) technique is developed and applied to provide solutions for continuum jets interacting with rarefied external flows. The technique is based on a correlation of the appropriate Bird breakdown parameter for a transitional-rarefied condition that defines a surface within which the continuum solution is unaffected by the external flow-jet interaction. The method is applied to two problems to assess and demonstrate its validity; one of a jet interaction in the transitional-rarefied flow regime and the other in the moderately rarefied regime. Results show that the appropriate Bird breakdown surface for uncoupling the continuum and non-continuum solutions is a function of a non-dimensional parameter relating the momentum flux and collisionality between the two interacting flows. The correlation is exploited for the simulation of a jet interaction modeled for an experimental condition in the transitional-rarefied flow regime and the validity of the correlation is demonstrated. The uncoupled technique is also applied to an aerobraking flight condition for the Mars Global Surveyor spacecraft with attitude control system jet interaction. Aerodynamic yawing moment coefficients for cases without and with jet interaction at various angles-of-attack were predicted, and results from the present method compare well with values published previously. The flow field and surface properties are analyzed in some detail to describe the mechanism by which the jet interaction affects the aerodynamics.

Renal transplantation induces mitochondrial uncoupling, increased kidney oxygen consumption, and decreased kidney oxygen tension.

PubMed

Papazova, Diana A; Friederich-Persson, Malou; Joles, Jaap A; Verhaar, Marianne C

2015-01-01

Hypoxia is an acknowledged pathway to renal injury and ischemia-reperfusion (I/R) and is known to reduce renal oxygen tension (Po2). We hypothesized that renal I/R increases oxidative damage and induces mitochondrial uncoupling, resulting in increased oxygen consumption and hence kidney hypoxia. Lewis rats underwent syngenic renal transplantation (TX) and contralateral nephrectomy. Controls were uninephrectomized (1K-CON) or left untreated (2K-CON). After 7 days, urinary excretion of protein and thiobarbituric acid-reactive substances were measured, and after 14 days glomerular filtration rate (GFR), renal blood flow, whole kidney Qo2, cortical Po2, kidney cortex mitochondrial uncoupling, renal oxidative damage, and tubulointerstitial injury were assessed. TX, compared with 1K-CON, resulted in mitochondrial uncoupling mediated via uncoupling protein-2 (16 ± 3.3 vs. 0.9 ± 0.4 pmol O2 · s(-1)· mg protein(-1), P < 0.05) and increased whole kidney Qo2 (55 ± 16 vs. 33 ± 10 μmol O2/min, P < 0.05). Corticomedullary Po2 was lower in TX compared with 1K-CON (30 ± 13 vs. 47 ± 4 μM, P < 0.05) whereas no significant difference was observed between 2K-CON and 1K-CON rats. Proteinuria, oxidative damage, and the tubulointerstitial injury score were not significantly different in 1K-CON and TX. Treatment of donors for 5 days with mito-TEMPO reduced mitochondrial uncoupling but did not affect renal hemodynamics, Qo2, Po2, or injury. Collectively, our results demonstrate increased mitochondrial uncoupling as an early event after experimental renal transplantation associated with increased oxygen consumption and kidney hypoxia in the absence of increases in markers of damage. Copyright © 2015 the American Physiological Society.

Free fatty acids as inducers and regulators of uncoupling of oxidative phosphorylation in liver mitochondria with participation of ADP/ATP- and aspartate/glutamate-antiporter.

PubMed

Samartsev, V N; Marchik, E I; Shamagulova, L V

2011-02-01

In liver mitochondria fatty acids act as protonophoric uncouplers mainly with participation of internal membrane protein carriers - ADP/ATP and aspartate/glutamate antiporters. In this study the values of recoupling effects of carboxyatractylate and glutamate (or aspartate) were used to assess the degree of participation of ADP/ATP and aspartate/glutamate antiporters in uncoupling activity of fatty acids. These values were determined from the ability of these recoupling agents to suppress the respiration stimulated by fatty acids and to raise the membrane potential reduced by fatty acids. Increase in palmitic and lauric acid concentration was shown to increase the degree of participation of ADP/ATP antiporter and to decrease the degree of participation of aspartate/glutamate antiporter in uncoupling to the same extent. These data suggest that fatty acids are not only inducers of uncoupling of oxidative phosphorylation, but that they also act the regulators of this process. The linear dependence of carboxyatractylate and glutamate recoupling effects ratio on palmitic and lauric acids concentration was established. Comparison of the effects of fatty acids (palmitic, myristic, lauric, capric, and caprylic having 16, 14, 12, 10, and 8 carbon atoms, respectively) has shown that, as the hydrophobicity of fatty acids decreases, the effectiveness decreases to a greater degree than the respective values of their specific uncoupling activity. The action of fatty acids as regulators of uncoupling is supposed to consist of activation of transport of their anions from the internal to the external monolayer of the internal membrane with participation of ADP/ATP antiporter and, at the same time, in inhibition of this process with the participation of aspartate/glutamate antiporter.

Asiatic acid uncouples respiration in isolated mouse liver mitochondria and induces HepG2 cells death.

PubMed

Lu, Yapeng; Liu, Siyuan; Wang, Ying; Wang, Dang; Gao, Jing; Zhu, Li

2016-09-05

Asiatic acid, one of the triterpenoid components isolated from Centella asiatica, has received increasing attention due to a wide variety of biological activities. To date, little is known about its mechanisms of action. Here we examined the cytotoxic effect of asiatic acid on HepG2 cells and elucidated some of the underlying mechanisms. Asiatic acid induced rapid cell death, as well as mitochondrial membrane potential (MMP) dissipation, ATP depletion and cytochrome c release from mitochondria to the cytosol in HepG2 cells. In mitochondria isolated from mouse liver, asiatic acid treatment significantly stimulated the succinate-supported state 4 respiration rate, dissipated the MMP, increased Ca(2+) release from Ca(2+)-loaded mitochondria, decreased ATP content and promoted cytochrome c release, indicating the uncoupling effect of asiatic acid. Hydrogen peroxide (H2O2) produced by succinate-supported mitochondrial respiration was also significantly inhibited by asiatic acid. In addition, asiatic acid inhibited Ca(2+)-induced mitochondrial swelling but did not induce mitochondrial swelling in hyposmotic potassium acetate medium which suggested that asiatic acid may not act as a protonophoric uncoupler. Inhibition of uncoupling proteins (UCPs) or blockade of adenine nucleotide transporter (ANT) attenuated the effect of asiatic acid on MMP dissipation, Ca(2+) release, mitochondrial respiration and HepG2 cell death. When combined inhibition of UCPs and ANT, asiatic acid-mediated uncoupling effect was noticeably alleviated. These results suggested that both UCPs and ANT partially contribute to the uncoupling properties of asiatic acid. In conclusion, asiatic acid is a novel mitochondrial uncoupler and this property is potentially involved in its toxicity on HepG2 cells. Copyright © 2016 Elsevier B.V. All rights reserved.

Inhibitors of V-ATPase proton transport reveal uncoupling functions of tether linking cytosolic and membrane domains of V0 subunit a (Vph1p).

PubMed

Chan, Chun-Yuan; Prudom, Catherine; Raines, Summer M; Charkhzarrin, Sahba; Melman, Sandra D; De Haro, Leyma P; Allen, Chris; Lee, Samuel A; Sklar, Larry A; Parra, Karlett J

2012-03-23

Vacuolar ATPases (V-ATPases) are important for many cellular processes, as they regulate pH by pumping cytosolic protons into intracellular organelles. The cytoplasm is acidified when V-ATPase is inhibited; thus we conducted a high-throughput screen of a chemical library to search for compounds that acidify the yeast cytosol in vivo using pHluorin-based flow cytometry. Two inhibitors, alexidine dihydrochloride (EC(50) = 39 μM) and thonzonium bromide (EC(50) = 69 μM), prevented ATP-dependent proton transport in purified vacuolar membranes. They acidified the yeast cytosol and caused pH-sensitive growth defects typical of V-ATPase mutants (vma phenotype). At concentrations greater than 10 μM the inhibitors were cytotoxic, even at the permissive pH (pH 5.0). Membrane fractions treated with alexidine dihydrochloride and thonzonium bromide fully retained concanamycin A-sensitive ATPase activity despite the fact that proton translocation was inhibited by 80-90%, indicating that V-ATPases were uncoupled. Mutant V-ATPase membranes lacking residues 362-407 of the tether of Vph1p subunit a of V(0) were resistant to thonzonium bromide but not to alexidine dihydrochloride, suggesting that this conserved sequence confers uncoupling potential to V(1)V(0) complexes and that alexidine dihydrochloride uncouples the enzyme by a different mechanism. The inhibitors also uncoupled the Candida albicans enzyme and prevented cell growth, showing further specificity for V-ATPases. Thus, a new class of V-ATPase inhibitors (uncouplers), which are not simply ionophores, provided new insights into the enzyme mechanism and original evidence supporting the hypothesis that V-ATPases may not be optimally coupled in vivo. The consequences of uncoupling V-ATPases in vivo as potential drug targets are discussed.

Effect of ethanol on the palmitate-induced uncoupling of oxidative phosphorylation in liver mitochondria.

PubMed

Samartsev, V N; Belosludtsev, K N; Chezganova, S A; Zeldi, I P

2002-11-01

The effect of ethanol on the uncoupling activity of palmitate and recoupling activities of carboxyatractylate and glutamate was studied in liver mitochondria at various Mg2+ concentrations and medium pH values (7.0, 7.4, and 7.8). Ethanol taken at concentration of 0.25 M had no effect on the uncoupling activity of palmitic acid in the presence of 2 mM MgCl2 and decreased the recoupling effects of carboxyatractylate and glutamate added to mitochondria either just before or after the fatty acid. However, ethanol did not modify the overall recoupling effect of carboxyatractylate and glutamate taken in combination. The effect of ethanol decreased as medium pH was decreased to 7.0. Elevated concentration of Mg2+ (up to 8 mM) inhibits the uncoupling effect of palmitate. Ethanol eliminates substantially the recoupling effect of Mg2+ under these conditions, but does not influence the recoupling effects of carboxyatractylate and glutamate. It is inferred that ADP/ATP and aspartate/glutamate antiporters are involved in uncoupling function as single uncoupling complex with the common fatty acid pool. Fatty acid molecules gain the ability to migrate under the action of ethanol: from ADP/ATP antiporter to aspartate/glutamate antiporter on addition of carboxyatractylate and in opposite direction on addition of glutamate. Possible mechanisms of fatty acid translocation from one transporter to another are discussed.

Uncoupling of intestinal mitochondrial oxidative phosphorylation and inhibition of cyclooxygenase are required for the development of NSAID-enteropathy in the rat.

PubMed

Somasundaram, S; Sigthorsson, G; Simpson, R J; Watts, J; Jacob, M; Tavares, I A; Rafi, S; Roseth, A; Foster, R; Price, A B; Wrigglesworth, J M; Bjarnason, I

2000-05-01

The pathogenesis of NSAID-induced gastrointestinal damage is believed to involve a nonprostaglandin dependent effect as well as prostaglandin dependent effects. One suggestion is that the nonprostaglandin mechanism involves uncoupling of mitochondrial oxidative phosphorylation. To assess the role of uncoupling of mitochondrial oxidative phosphorylation in the pathogenesis of small intestinal damage in the rat. We compared key pathophysiologic events in the small bowel following (i) dinitrophenol, an uncoupling agent (ii) parenteral aspirin, to inhibit cyclooxygenase without causing a 'topical' effect and (iii) the two together, using (iv) indomethacin as a positive control. Dinitrophenol altered intestinal mitochondrial morphology, increased intestinal permeability and caused inflammation without affecting gastric permeability or intestinal prostanoid levels. Parenteral aspirin decreased mucosal prostanoids without affecting intestinal mitochondria in vivo, gastric or intestinal permeability. Aspirin caused no inflammation or ulcers. When dinitrophenol and aspirin were given together the changes in intestinal mitochondrial morphology, permeability, inflammation and prostanoid levels and the macro- and microscopic appearances of intestinal ulcers were similar to indomethacin. These studies allow dissociation of the contribution and consequences of uncoupling of mitochondrial oxidative phosphorylation and cyclooxygenase inhibition in the pathophysiology of NSAID enteropathy. While uncoupling of enterocyte mitochondrial oxidative phosphorylation leads to increased intestinal permeability and low grade inflammation, concurrent decreases in mucosal prostanoids appear to be important in the development of ulcers.

The lampricide 3-trifluoromethyl-4-nitrophenol (TFM) uncouples mitochondrial oxidative phosphorylation in both sea lamprey (Petromyzon marinus) and TFM-tolerant rainbow trout (Oncorhynchus mykiss).

PubMed

Birceanu, Oana; McClelland, Grant B; Wang, Yuxiang S; Brown, Jason C L; Wilkie, Michael P

2011-04-01

The toxicity of 3-trifluoromethyl-4-nitrophenol (TFM) appears to be due to a mismatch between ATP supply and demand in lamprey, depleting glycogen stores and starving the nervous system of ATP. The cause of this TFM-induced ATP deficit is unclear. One possibility is that TFM uncouples mitochondrial oxidative phosphorylation, thus impairing ATP production. To test this hypothesis, mitochondria were isolated from the livers of sea lamprey and rainbow trout, and O(2) consumption rates were measured in the presence of TFM or 2,4-dinitrophenol (2,4-DNP), a known uncoupler of oxidative phosphorylation. TFM and 2,4-DNP markedly increased State IV respiration in a dose-dependent fashion, but had no effect on State III respiration, which is consistent with uncoupling of oxidative phosphorylation. To determine how TFM uncoupled oxidative phosphorylation, the mitochondrial transmembrane potential (TMP) was recorded using the mitochondria-specific dye rhodamine 123. Mitochondrial TMP decreased by 22% in sea lamprey, and by 28% in trout following treatment with 50μmolL(-1) TFM. These findings suggest that TFM acted as a protonophore, dissipating the proton motive force needed to drive ATP synthesis. We conclude that the mode of TFM toxicity in sea lamprey and rainbow trout is via uncoupling of oxidative phosphorylation, leading to impaired ATP production. Copyright © 2010 Elsevier Inc. All rights reserved.

Uncoupling of oxidative phosphorylation by curcumin: implication of its cellular mechanism of action.

PubMed

Lim, Han Wern; Lim, Hwee Ying; Wong, Kim Ping

2009-11-06

Curcumin is a phytochemical isolated from the rhizome of turmeric. Recent reports have shown curcumin to have antioxidant, anti-inflammatory and anti-tumor properties as well as affecting the 5'-AMP activated protein kinase (AMPK), mTOR and STAT-3 signaling pathways. We provide evidence that curcumin acts as an uncoupler. Well-established biochemical techniques were performed on isolated rat liver mitochondria in measuring oxygen consumption, F(0)F(1)-ATPase activity and ATP biosynthesis. Curcumin displays all the characteristics typical of classical uncouplers like fccP and 2,4-dinitrophenol. In addition, at concentrations higher than 50 microM, curcumin was found to inhibit mitochondrial respiration which is a characteristic feature of inhibitory uncouplers. As a protonophoric uncoupler and as an activator of F(0)F(1)-ATPase, curcumin causes a decrease in ATP biosynthesis in rat liver mitochondria. The resulting change in ATP:AMP could disrupt the phosphorylation status of the cell; this provides a possible mechanism for its activation of AMPK and its downstream mTOR and STAT-3 signaling.

Uncoupling Mitochondrial Respiration for Diabesity.

PubMed

Larrick, James W; Larrick, Jasmine W; Mendelsohn, Andrew R

2016-08-01

Until recently, the mechanism of adaptive thermogenesis was ascribed to the expression of uncoupling protein 1 (UCP1) in brown and beige adipocytes. UCP1 is known to catalyze a proton leak of the inner mitochondrial membrane, resulting in uncoupled oxidative metabolism with no production of adenosine triphosphate and increased energy expenditure. Thus increasing brown and beige adipose tissue with augmented UCP1 expression is a viable target for obesity-related disorders. Recent work demonstrates an UCP1-independent pathway to uncouple mitochondrial respiration. A secreted enzyme, PM20D1, enriched in UCP1+ adipocytes, exhibits catalytic and hydrolytic activity to reversibly form N-acyl amino acids. N-acyl amino acids act as endogenous uncouplers of mitochondrial respiration at physiological concentrations. Administration of PM20D1 or its products, N-acyl amino acids, to diet-induced obese mice improves glucose tolerance by increasing energy expenditure. In short-term studies, treated animals exhibit no toxicity while experiencing 10% weight loss primarily of adipose tissue. Further study of this metabolic pathway may identify novel therapies for diabesity, the disease state associated with diabetes and obesity.

Uncoupling of oxidative phosphorylation by curcumin: Implication of its cellular mechanism of action

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Han Wern; Lim, Hwee Ying; Wong, Kim Ping, E-mail: bchsitkp@nus.edu.sg

2009-11-06

Curcumin is a phytochemical isolated from the rhizome of turmeric. Recent reports have shown curcumin to have antioxidant, anti-inflammatory and anti-tumor properties as well as affecting the 5'-AMP activated protein kinase (AMPK), mTOR and STAT-3 signaling pathways. We provide evidence that curcumin acts as an uncoupler. Well-established biochemical techniques were performed on isolated rat liver mitochondria in measuring oxygen consumption, F{sub 0}F{sub 1}-ATPase activity and ATP biosynthesis. Curcumin displays all the characteristics typical of classical uncouplers like fccP and 2,4-dinitrophenol. In addition, at concentrations higher than 50 {mu}M, curcumin was found to inhibit mitochondrial respiration which is a characteristic featuremore » of inhibitory uncouplers. As a protonophoric uncoupler and as an activator of F{sub 0}F{sub 1}-ATPase, curcumin causes a decrease in ATP biosynthesis in rat liver mitochondria. The resulting change in ATP:AMP could disrupt the phosphorylation status of the cell; this provides a possible mechanism for its activation of AMPK and its downstream mTOR and STAT-3 signaling.« less

Dnmt1-dependent Chk1 pathway suppression is protective against neuron division.

PubMed

Oshikawa, Mio; Okada, Kei; Tabata, Hidenori; Nagata, Koh-Ichi; Ajioka, Itsuki

2017-09-15

Neuronal differentiation and cell-cycle exit are tightly coordinated, even in pathological situations. When pathological neurons re-enter the cell cycle and progress through the S phase, they undergo cell death instead of division. However, the mechanisms underlying mitotic resistance are mostly unknown. Here, we have found that acute inactivation of retinoblastoma (Rb) family proteins (Rb, p107 and p130) in mouse postmitotic neurons leads to cell death after S-phase progression. Checkpoint kinase 1 (Chk1) pathway activation during the S phase prevented the cell death, and allowed the division of cortical neurons that had undergone acute Rb family inactivation, oxygen-glucose deprivation (OGD) or in vivo hypoxia-ischemia. During neurogenesis, cortical neurons became protected from S-phase Chk1 pathway activation by the DNA methyltransferase Dnmt1, and underwent cell death after S-phase progression. Our results indicate that Chk1 pathway activation overrides mitotic safeguards and uncouples neuronal differentiation from mitotic resistance. © 2017. Published by The Company of Biologists Ltd.

Quantitative analysis of circadian single cell oscillations in response to temperature

PubMed Central

Kramer, Achim; Herzel, Hanspeter

2018-01-01

Body temperature rhythms synchronize circadian oscillations in different tissues, depending on the degree of cellular coupling: the responsiveness to temperature is higher when single circadian oscillators are uncoupled. So far, the role of coupling in temperature responsiveness has only been studied in organotypic tissue slices of the central circadian pacemaker, because it has been assumed that peripheral target organs behave like uncoupled multicellular oscillators. Since recent studies indicate that some peripheral tissues may exhibit cellular coupling as well, we asked whether peripheral network dynamics also influence temperature responsiveness. Using a novel technique for long-term, high-resolution bioluminescence imaging of primary cultured cells, exposed to repeated temperature cycles, we were able to quantitatively measure period, phase, and amplitude of central (suprachiasmatic nuclei neuron dispersals) and peripheral (mouse ear fibroblasts) single cell oscillations in response to temperature. Employing temperature cycles of different lengths, and different cell densities, we found that some circadian characteristics appear cell-autonomous, e.g. period responses, while others seem to depend on the quality/degree of cellular communication, e.g. phase relationships, robustness of the oscillation, and amplitude. Overall, our findings indicate a strong dependence on the cell’s ability for intercellular communication, which is not only true for neuronal pacemakers, but, importantly, also for cells in peripheral tissues. Hence, they stress the importance of comparative studies that evaluate the degree of coupling in a given tissue, before it may be used effectively as a target for meaningful circadian manipulation. PMID:29293562

Control of Retrograde Signaling by Rapid Turnover of GENOMES UNCOUPLED11[OPEN

PubMed Central

Chalvin, Camille; Wu, Xu Na

2018-01-01

The exchange of signals between cellular compartments coordinates development and differentiation, modulates metabolic pathways, and triggers responses to environmental conditions. The proposed central regulator of plastid-to-nucleus retrograde signaling, GENOMES UNCOUPLED1 (GUN1), is present at very low levels, which has hampered the discovery of its precise molecular function. Here, we show that the Arabidopsis (Arabidopsis thaliana) GUN1 protein accumulates to detectable levels only at very early stages of leaf development, where it functions in the regulation of chloroplast biogenesis. GUN1 mRNA is present at high levels in all tissues, but GUN1 protein undergoes rapid degradation (with an estimated half-life of ∼4 h) in all tissues where chloroplast biogenesis has been completed. The rapid turnover of GUN1 is controlled mainly by the chaperone ClpC1, suggesting degradation of GUN1 by the Clp protease. Degradation of GUN1 slows under stress conditions that alter retrograde signaling, thus ensuring that the plant has sufficient GUN1 protein. We also find that the pentatricopeptide repeat motifs of GUN1 are important determinants of GUN1 stability. Moreover, overexpression of GUN1 causes an early flowering phenotype, suggesting a function of GUN1 in developmental phase transitions beyond chloroplast biogenesis. Taken together, our results provide new insight into the regulation of GUN1 by proteolytic degradation, uncover its function in early chloroplast biogenesis, and suggest a role in developmental phase transitions. PMID:29367233

Systems design study of the Pioneer Venus spacecraft. Appendices to volume 1, section 7 (part 2 of 3). [procedures for predicting aeroheating environment of Venus entry probes

NASA Technical Reports Server (NTRS)

1973-01-01

The procedures for predicting the aeroheating environment of Venus entry probes are outlined. After some consideration, a number of assumptions were adopted in order to make the prediction techniques tractable. Among these assumptions are thermochemical equilibrium, uncoupled radiative and convective processes, and uncoupled ablation products effects. The single strip method of integral relations, appropriately constrained, is shown to provide adequate inviscid results as a basis for heating calculations on blunt configurations. Techniques for prediction of the laminar, transitional, and turbulent convective environment are outlined and shown to agree with data. The prediction of radiative heating in C, N, and O gas mixtures is discussed and a practical scheme adopted. A comparison with LRC calculations is made.

Targeting NADPH Oxidase Decreases Oxidative Stress in the Transgenic Sickle Cell Mouse Penis

PubMed Central

Musicki, Biljana; Liu, Tongyun; Sezen, Sena F.; Burnett, Arthur L.

2012-01-01

Introduction Sickle cell disease (SCD) is a state of chronic vasculopathy characterized by endothelial dysfunction and increased oxidative stress, but the sources and mechanisms responsible for reactive oxygen species (ROS) production in the penis are unknown. Aims We evaluated whether SCD activates NADPH oxidase, induces endothelial nitric oxide synthase (eNOS) uncoupling, and decreases antioxidants in the SCD mouse penis. We further tested the hypothesis that targeting NADPH oxidase decreases oxidative stress in the SCD mouse penis. Methods SCD transgenic (sickle) mice were used as an animal model of SCD. Hemizygous (hemi) mice served as controls. Mice received an NADPH oxidase inhibitor apocynin (10 mM in drinking water) or vehicle. Penes were excised at baseline for molecular studies. Markers of oxidative stress (4-hydroxy-2-nonenal [HNE]), sources of ROS (eNOS uncoupling and NADPH oxidase subunits p67phox, p47phox, and gp91phox), and enzymatic antioxidants (superoxide dismutase [SOD]1, SOD2, catalase, and glutathione peroxidase-1 [GPx1]) were measured by Western blot in penes. Main Outcome Measures Sources of ROS, oxidative stress, and enzymatic antioxidants in the SCD penis. Results Relative to hemi mice, SCD increased (P < 0.05) protein expression of NADPH oxidase subunits p67phox, p47phox, and gp91phox, 4-HNE-modified proteins, induced eNOS uncoupling, and reduced Gpx1 expression in the penis. Apocynin treatment of sickle mice reversed (P < 0.05) the abnormalities in protein expressions of p47phox, gp91phox (but not p67phox) and 4-HNE, but only slightly (P > 0.05) prevented eNOS uncoupling in the penis. Apocynin treatment of hemi mice did not affect any of these parameters. Conclusion NADPH oxidase and eNOS uncoupling are sources of oxidative stress in the SCD penis; decreased GPx1 further contributes to oxidative stress. Inhibition of NADPH oxidase upregulation decreases oxidative stress, implying a major role for NADPH oxidase as a ROS source and a potential target for improving vascular function in the SCD mouse penis. PMID:22620981

Solving the Coupled System Improves Computational Efficiency of the Bidomain Equations

PubMed Central

Southern, James A.; Plank, Gernot; Vigmond, Edward J.; Whiteley, Jonathan P.

2017-01-01

The bidomain equations are frequently used to model the propagation of cardiac action potentials across cardiac tissue. At the whole organ level the size of the computational mesh required makes their solution a significant computational challenge. As the accuracy of the numerical solution cannot be compromised, efficiency of the solution technique is important to ensure that the results of the simulation can be obtained in a reasonable time whilst still encapsulating the complexities of the system. In an attempt to increase efficiency of the solver, the bidomain equations are often decoupled into one parabolic equation that is computationally very cheap to solve and an elliptic equation that is much more expensive to solve. In this study the performance of this uncoupled solution method is compared with an alternative strategy in which the bidomain equations are solved as a coupled system. This seems counter-intuitive as the alternative method requires the solution of a much larger linear system at each time step. However, in tests on two 3-D rabbit ventricle benchmarks it is shown that the coupled method is up to 80% faster than the conventional uncoupled method — and that parallel performance is better for the larger coupled problem. PMID:19457741

Burn after feeding. An old uncoupler of oxidative phosphorylation is redesigned for the treatment of nonalcoholic fatty liver disease.

PubMed

Fromenty, B

2014-10-01

Uncoupling of oxidative phosphorylation (OXPHOS) in brown adipose tissue can be used by hibernating animals to produce heat at the expense of their fat mass. In a recent work, Dr Shulman et al. generated a liver-targeted derivative of the prototypical OXPHOS uncoupler 2,4-dinitrophenol that alleviated steatosis, hypertriglyceridemia and insulin resistance in several models of nonalcoholic fatty liver disease and type 2 diabetes. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Gene-gene interactions among genetic variants from obesity candidate genes for nonobese and obese populations in type 2 diabetes.

PubMed

Lin, Eugene; Pei, Dee; Huang, Yi-Jen; Hsieh, Chang-Hsun; Wu, Lawrence Shih-Hsin

2009-08-01

Recent studies indicate that obesity may play a key role in modulating genetic predispositions to type 2 diabetes (T2D). This study examines the main effects of both single-locus and multilocus interactions among genetic variants in Taiwanese obese and nonobese individuals to test the hypothesis that obesity-related genes may contribute to the etiology of T2D independently and/or through such complex interactions. We genotyped 11 single nucleotide polymorphisms for 10 obesity candidate genes including adrenergic beta-2-receptor surface, adrenergic beta-3-receptor surface, angiotensinogen, fat mass and obesity associated gene, guanine nucleotide binding protein beta polypeptide 3 (GNB3), interleukin 6 receptor, proprotein convertase subtilisin/kexin type 1 (PCSK1), uncoupling protein 1, uncoupling protein 2, and uncoupling protein 3. There were 389 patients diagnosed with T2D and 186 age- and sex-matched controls. Single-locus analyses showed significant main effects of the GNB3 and PCSK1 genes on the risk of T2D among the nonobese group (p = 0.002 and 0.047, respectively). Further, interactions involving GNB3 and PCSK1 were suggested among the nonobese population using the generalized multifactor dimensionality reduction method (p = 0.001). In addition, interactions among angiotensinogen, fat mass and obesity associated gene, GNB3, and uncoupling protein 3 genes were found in a significant four-locus generalized multifactor dimensionality reduction model among the obese population (p = 0.001). The results suggest that the single nucleotide polymorphisms from the obesity candidate genes may contribute to the risk of T2D independently and/or in an interactive manner according to the presence or absence of obesity.

Effect of surfactants on apparent oxygen consumption of photosystem I isolated from Arthrospira platensis.

PubMed

Yu, Daoyong; Huang, Guihong; Xu, Fengxi; Ge, Baosheng; Liu, Shuang; Xu, Hai; Huang, Fang

2014-11-01

Surfactants play a significant role in solubilization of photosystem I (PSI) in vitro. Triton X-100 (TX), n-Dodecyl-β-D-maltoside (DDM), and sodium dodecyl sulfate (SDS) were employed to solubilize PSI particles in MES buffer to compare the effect of surfactant and its dosage on the apparent oxygen consumption rate of PSI. Through a combined assessment of sucrose density gradient centrifugation, Native PAGE and 77 K fluorescence with the apparent oxygen consumption, the nature of the enhancement of the apparent oxygen consumption activity of PSI by surfactants has been analyzed. Aggregated PSI particles can be dispersed by surfactant molecules into micelles, and the apparent oxygen consumption rate is higher for surfactant-solubilized PSI than for integral PSI particles. For DDM, PSI particles are solubilized mostly as the integral trimeric form. For TX, PSI particles are solubilized as incomplete trimeric and some monomeric forms. For the much harsher surfactant, SDS, PSI particles are completely solubilized as monomeric and its subunit forms. The enhancement of the oxygen consumption rate cannot be explained only by the effects of surfactant on the equilibrium between monomeric and trimeric forms of solubililized PSI. Care must be taken when the electron transfer activity of PSI is evaluated by methods based on oxygen consumption because the apparent oxygen consumption rate is influenced by uncoupled chlorophyll (Chl) from PSI, i.e., the larger the amount of uncoupled Chl, the higher the rate of apparent oxygen consumption. 77 K fluorescence spectra can be used to ensure that there is no uncoupled Chl present in the system. In order to eliminate the effect of trace uncoupled Chl, an efficient physical quencher of (1)O2, such as 1 mM NaN3, may be added into the mixture.

Intrinsic and extrinsic uncoupling of oxidative phosphorylation.

PubMed

Kadenbach, Bernhard

2003-06-05

This article reviews parameters of extrinsic uncoupling of oxidative phosphorylation (OxPhos) in mitochondria, based on induction of a proton leak across the inner membrane. The effects of classical uncouplers, fatty acids, uncoupling proteins (UCP1-UCP5) and thyroid hormones on the efficiency of OxPhos are described. Furthermore, the present knowledge on intrinsic uncoupling of cytochrome c oxidase (decrease of H(+)/e(-) stoichiometry=slip) is reviewed. Among the three proton pumps of the respiratory chain of mitochondria and bacteria, only cytochrome c oxidase is known to exhibit a slip of proton pumping. Intrinsic uncoupling was shown after chemical modification, by site-directed mutagenesis of the bacterial enzyme, at high membrane potential DeltaPsi, and in a tissue-specific manner to increase thermogenesis in heart and skeletal muscle by high ATP/ADP ratios, and in non-skeletal muscle tissues by palmitate. In addition, two mechanisms of respiratory control are described. The first occurs through the membrane potential DeltaPsi and maintains high DeltaPsi values (150-200 mV). The second occurs only in mitochondria, is suggested to keep DeltaPsi at low levels (100-150 mV) through the potential dependence of the ATP synthase and the allosteric ATP inhibition of cytochrome c oxidase at high ATP/ADP ratios, and is reversibly switched on by cAMP-dependent phosphorylation. Finally, the regulation of DeltaPsi and the production of reactive oxygen species (ROS) in mitochondria at high DeltaPsi values (150-200 mV) are discussed.

Ursolic Acid-enriched herba cynomorii extract induces mitochondrial uncoupling and glutathione redox cycling through mitochondrial reactive oxygen species generation: protection against menadione cytotoxicity in h9c2 cells.

PubMed

Chen, Jihang; Wong, Hoi Shan; Ko, Kam Ming

2014-01-27

Herba Cynomorii (Cynomorium songaricum Rupr., Cynomoriaceae) is one of the most commonly used 'Yang-invigorating' tonic herbs in Traditional Chinese Medicine (TCM). An earlier study in our laboratory has demonstrated that HCY2, an ursolic acid-enriched fraction derived from Herba Cynomorii, increased mitochondrial ATP generation capacity (ATP-GC) and induced mitochondrial uncoupling as well as a cellular glutathione response, thereby protecting against oxidant injury in H9c2 cells. In this study, we demonstrated that pre-incubation of H9c2 cells with HCY2 increased mitochondrial reactive oxygen species (ROS) generation in these cells, which is likely an event secondary to the stimulation of the mitochondrial electron transport chain. The suppression of mitochondrial ROS by the antioxidant dimethylthiourea abrogated the HCY2-induced enhancement of mitochondrial uncoupling and glutathione reductase (GR)-mediated glutathione redox cycling, and also protected against menadione-induced cytotoxicity. Studies using specific inhibitors of uncoupling protein and GR suggested that the HCY2-induced mitochondrial uncoupling and glutathione redox cycling play a determining role in the cytoprotection against menadione-induced oxidant injury in H9c2 cells. Experimental evidence obtained thus far supports the causal role of HCY2-induced mitochondrial ROS production in eliciting mitochondrial uncoupling and glutathione antioxidant responses, which offer cytoprotection against oxidant injury in H9c2 cells.

Uncoupling of oxidative phosphorylation enables Candida albicans to resist killing by phagocytes and persist in tissue.

PubMed

Cheng, Shaoji; Clancy, Cornelius J; Zhang, Zongde; Hao, Binghua; Wang, Wei; Iczkowski, Kenneth A; Pfaller, Michael A; Nguyen, M Hong

2007-02-01

After five serial passages of Candida albicans SC5314 through murine spleens by intravenous inoculation, we recovered a respiratory mutant (strain P5) that exhibited reduced colony size, stunted growth in glucose-deficient media, increased oxygen consumption and defective carbohydrate assimilation. Strain P5 was indistinguishable from SC5314 by DNA typing methods, but had a greater concentration of mitochondria by SYTO18 staining. Treatment with various inhibitors demonstrated that strain P5's electron transport chain was intact and oxidative phosphorylation was uncoupled. During disseminated candidiasis, the mutant did not kill mice or cause extensive damage to kidneys. The burden of strain P5 within kidneys on the first 3 days of disseminated candidiasis was significantly reduced. By days 28 and 60, it was similar to that at the time of death among mice infected with SC5314, suggesting that the mutant persisted and proliferated without killing mice. Strain P5 was resistant to phagocytosis by neutrophils and macrophages. It was also significantly more resistant to paraquat, suggesting that it is able to neutralize reactive oxygen species. Our findings indicate that regulation of respiration influences the interaction between C. albicans and the host. Uncoupling of oxidative phosphorylation might be a mechanism by which the organism adapts to stressful host environments.

Raised intracellular [Ca2+] abolishes excitation-contraction coupling in skeletal muscle fibres of rat and toad.

PubMed Central

Lamb, G D; Junankar, P R; Stephenson, D G

1995-01-01

1. Raising the intracellular [Ca2+] for 10 s at 23 degrees C abolished depolarization-induced force responses in mechanically skinned muscle fibres of toad and rat (half-maximal effect at 10 and 23 microM, respectively), without affecting the ability of caffeine or low [Mg2+] to open the ryanodine receptor (RyR)/Ca2+ release channels. Thus, excitation-contraction coupling was lost, even though the Ca2+ release channels were still functional. Coupling could not be restored in the duration of an experiment (up to 1 h). 2. The Ca(2+)-dependent uncoupling had a Q10 > 3.5, and was three times slower at pH 5.8 than at pH 7.1. Sr2+ caused similar uncoupling at twenty times higher concentration, but Mg2+, even at 10 mM, was ineffective. Uncoupling was not noticeably affected by removal of ATP or application of protein kinase or phosphatase inhibitors. 3. Confocal laser scanning microscopy showed that the transverse tubular system was sealed in its entirety in mechanically skinned fibres and that its integrity was maintained in uncoupled fibres. Electron microscopy revealed distorted or severed triad junctions and Z-line aberrations in uncoupled fibres. 4. Only when uncoupling was induced at a relatively slow rate (e.g. over 60 s with 2.5 microM Ca2+) could it be prevented by the protease inhibitor leupeptin (1 mM). Immunostaining of Western blots showed no evidence of proteolysis of the RyR, the alpha 1-subunit of dihydropyridine receptor (DHPR) or triadin in uncoupled fibres. 5. Fibres which, whilst intact, were stimulated repeatedly by potassium depolarization with simultaneous application of 30 mM caffeine showed reduced responsiveness after skinning to depolarization but not to caffeine. Rapid release of endogenous Ca2+, or raised [Ca2+] under conditions which minimized the loss of endogenous diffusible myoplasmic molecules from the skinned fibre, caused complete uncoupling. Taken together, these results suggest that Ca(2+)-dependent uncoupling can also occur in intact fibres. 6. This Ca(2+)-dependent loss of depolarization-induced Ca2+ release may play an important feedback role in muscle by stopping Ca2+ release in localized areas where it is excessive and may be responsible for long-lasting muscle fatigue after severe exercise, as well as contributing to muscle weakness in various dystrophies. Images Figure 1 Figure 7 Figure 9 PMID:8847631

Analysis of structural dynamic data from Skylab. Volume 2: Skylab analytical and test model data

NASA Technical Reports Server (NTRS)

Demchak, L.; Harcrow, H.

1976-01-01

The orbital configuration test modal data, analytical test correlation modal data, and analytical flight configuration modal data are presented. Tables showing the generalized mass contributions (GMCs) for each of the thirty tests modes are given along with the two dimensional mode shape plots and tables of GMCs for the test correlated analytical modes. The two dimensional mode shape plots for the analytical modes and uncoupled and coupled modes of the orbital flight configuration at three development phases of the model are included.

Control, synchronization, and enhanced reliability of aperiodic oscillations in the Mercury Beating Heart system

NASA Astrophysics Data System (ADS)

Kumar, Pawan; Parmananda, P.

2018-04-01

Experiments involving the Mercury Beating Heart (MBH) oscillator, exhibiting irregular (aperiodic) dynamics, are performed. In the first set of experiments, control over irregular dynamics of the MBH oscillator was obtained via a superimposed periodic voltage signal. These irregular (aperiodic) dynamics were recovered once the control was switched off. Subsequently, two MBH oscillators were coupled to attain synchronization of their aperiodic oscillations. Finally, two uncoupled MBH oscillators were subjected, repeatedly, to a common stochastic forcing, resulting in an enhancement of their mutual phase correlation.

Adenovirus type 5 induces progression of quiescent rat cells into S phase without polyamine accumulation.

PubMed Central

Cheetham, B F; Shaw, D C; Bellett, A J

1982-01-01

Adenovirus type 5 induces cellular DNA synthesis and thymidine kinase in quiescent rat cells but does not induce ornithine decarboxylase. We now show that unlike serum, adenovirus type 5 fails to induce S-adenosylmethionine decarboxylase or polyamine accumulation. The inhibition by methylglyoxal bis(guanylhydrazone) of the induction of thymidine kinase by adenovirus type 5 is probably unrelated to its effects on polyamine biosynthesis. Thus, induction of cellular thymidine kinase and DNA replication by adenovirus type 5 is uncoupled from polyamine accumulation. PMID:7177112

Hydroxynonenal-stimulated activity of the uncoupling protein in Acanthamoeba castellanii mitochondria under phosphorylating conditions.

PubMed

Woyda-Ploszczyca, Andrzej; Jarmuszkiewicz, Wieslawa

2013-05-01

The influence of 4-hydroxy-2-nonenal (HNE), a lipid peroxidation end product, on the activity of the amoeba Acanthamoeba castellanii uncoupling protein (AcUCP) in isolated phosphorylating mitochondria was studied. Under phosphorylating conditions, exogenously added HNE induced GTP-sensitive AcUCP-mediated mitochondrial uncoupling. The HNE-induced proton leak decreased the yield of oxidative phosphorylation in an HNE concentration-dependent manner. The present study describes how the contributions of ATP synthase and HNE-induced AcUCP in phosphorylating respiration vary when the rate of succinate oxidation is decreased by limiting succinate uptake or inhibiting complex III activity within the range of a constant membrane potential. In phosphorylating mitochondria, at a given HNE concentration (100 μM), the efficiency of AcUCP in mitochondrial uncoupling increased as the respiratory rate decreased because the AcUCP contribution remained constant while the ATP synthase contribution decreased with the respiratory rate. HNE-induced uncoupling can be inhibited by GTP only when ubiquinone is sufficiently oxidized, indicating that in phosphorylating A. castellanii mitochondria, the sensitivity of AcUCP activity to GTP depends on the redox state of the membranous ubiquinone.

Hyperthyroidism increases the uncoupled ATPase activity and heat production by the sarcoplasmic reticulum Ca2+-ATPase.

PubMed

Arruda, Ana Paula; Da-Silva, Wagner S; Carvalho, Denise P; De Meis, Leopoldo

2003-11-01

The sarcoplasmic reticulum Ca2+-ATPase is able to modulate the distribution of energy released during ATP hydrolysis, so that a portion of energy is used for Ca2+ transport (coupled ATPase activity) and a portion is converted into heat (uncoupled ATPase activity). In this report it is shown that T4 administration to rabbits promotes an increase in the rates of both the uncoupled ATPase activity and heat production in sarcoplasmic reticulum vesicles, and that the degree of activation varies depending on the muscle type used. In white muscles hyperthyroidism promotes a 0.8-fold increase of the uncoupled ATPase activity and in red muscle a 4-fold increase. The yield of vesicles from hyperthyroid muscles is 3-4-fold larger than that obtained from normal muscles; thus the rate of heat production by the Ca2+-ATPase expressed in terms of g of muscle in hyperthyroidism is increased by a factor of 3.6 in white muscles and 12.0 in red muscles. The data presented suggest that the Ca2+-ATPase uncoupled activity may represent one of the heat sources that contributes to the enhanced thermogenesis noted in hyperthyroidism.

A Method for Incorporating Changing Structural Characteristics Due to Propellant Mass Usage in a Launch Vehicle Ascent Simulation

NASA Technical Reports Server (NTRS)

McGhee, D. S.

2004-01-01

Launch vehicles consume large quantities of propellant quickly, causing the mass properties and structural dynamics of the vehicle to change dramatically. Currently, structural load assessments account for this change with a large collection of structural models representing various propellant fill levels. This creates a large database of models complicating the delivery of reduced models and requiring extensive work for model changes. Presented here is a method to account for these mass changes in a more efficient manner. The method allows for the subtraction of propellant mass as the propellant is used in the simulation. This subtraction is done in the modal domain of the vehicle generalized model. Additional computation required is primarily for constructing the used propellant mass matrix from an initial propellant model and further matrix multiplications and subtractions. An additional eigenvalue solution is required to uncouple the new equations of motion; however, this is a much simplier calculation starting from a system that is already substantially uncoupled. The method was successfully tested in a simulation of Saturn V loads. Results from the method are compared to results from separate structural models for several propellant levels, showing excellent agreement. Further development to encompass more complicated propellant models, including slosh dynamics, is possible.

Respiratory uncoupling by increased H(+) or K(+) flux is beneficial for heart mitochondrial turnover of reactive oxygen species but not for permeability transition.

PubMed

Morota, Saori; Piel, Sarah; Hansson, Magnus J

2013-09-22

Ischemic preconditioning has been proposed to involve changes in mitochondrial H(+) and K(+) fluxes, in particular through activation of uncoupling proteins and ATP-sensitive K(+) channels (MitoKATP). The objectives of the present study were to explore how increased H(+) and K(+) fluxes influence heart mitochondrial physiology with regard to production and scavenging of reactive oxygen species (ROS), volume changes and resistance to calcium-induced mitochondrial permeability transition (mPT). Isolated rat heart mitochondria were exposed to a wide concentration range of the protonophore CCCP or the potassium ionophore valinomycin to induce increased H(+) and K(+) conductance, respectively. Simultaneous monitoring of mitochondrial respiration and calcium retention capacity (CRC) demonstrated that the relative increase in respiration caused by valinomycin or CCCP correlated with a decrease in CRC, and that no level of respiratory uncoupling was associated with enhanced resistance to mPT. Mitochondria suspended in hyperosmolar buffer demonstrated a dose-dependent reduction in CRC with increasing osmolarity. However, mitochondria in hypoosmolar buffer to increase matrix volume did not display increased CRC. ROS generation was reduced by both K(+)- and H(+)-mediated respiratory uncoupling. The ability of heart mitochondria to detoxify H2O2 was substantially greater than the production rate. The H2O2 detoxification was dependent on respiratory substrates and was dramatically decreased following calcium-induced mPT, but was unaffected by uncoupling via increased K(+) and H(+) conductance. It is concluded that respiratory uncoupling is not directly beneficial to rat heart mitochondrial resistance to calcium overload irrespective of whether H(+) or K(+) conductance is increased. The negative effects of respiratory uncoupling thus probably outweigh the reduction in ROS generation and a potential positive effect by increased matrix volume, resulting in a net sensitization of heart mitochondria to mPT activation.

Low shear stress induces vascular eNOS uncoupling via autophagy-mediated eNOS phosphorylation.

PubMed

Zhang, Jun-Xia; Qu, Xin-Liang; Chu, Peng; Xie, Du-Jiang; Zhu, Lin-Lin; Chao, Yue-Lin; Li, Li; Zhang, Jun-Jie; Chen, Shao-Liang

2018-05-01

Uncoupled endothelial nitric oxide synthase (eNOS) produces O 2 - instead of nitric oxide (NO). Earlier, we reported rapamycin, an autophagy inducer and inhibitor of cellular proliferation, attenuated low shear stress (SS) induced O 2 - production. Nevertheless, it is unclear whether autophagy plays a critical role in the regulation of eNOS uncoupling. Therefore, this study aimed to investigate the modulation of autophagy on eNOS uncoupling induced by low SS exposure. We found that low SS induced endothelial O 2 - burst, which was accompanied by reduced NO release. Furthermore, inhibition of eNOS by L-NAME conspicuously attenuated low SS-induced O 2 - releasing, indicating eNOS uncoupling. Autophagy markers such as LC3 II/I ratio, amount of Beclin1, as well as ULK1/Atg1 were increased during low SS exposure, whereas autophagic degradation of p62/SQSTM1 was markedly reduced, implying impaired autophagic flux. Interestingly, low SS-induced NO reduction could be reversed by rapamycin, WYE-354 or ATG5 overexpression vector via restoration of autophagic flux, but not by N-acetylcysteine or apocynin. eNOS uncoupling might be ascribed to autophagic flux blockade because phosphorylation of eNOS Thr495 by low SS or PMA stimulation was also regulated by autophagy. In contrast, eNOS acetylation was not found to be regulated by low SS and autophagy. Notably, although low SS had no influence on eNOS Ser1177 phosphorylation, whereas boosted eNOS Ser1177 phosphorylation by rapamycin were in favor of the eNOS recoupling through restoration of autophagic flux. Taken together, we reported a novel mechanism for regulation of eNOS uncoupling by low SS via autophagy-mediated eNOS phosphorylation, which is implicated in geometrical nature of atherogenesis. Copyright © 2018 Elsevier B.V. All rights reserved.

An improved finite-difference analysis of uncoupled vibrations of tapered cantilever beams

NASA Technical Reports Server (NTRS)

Subrahmanyam, K. B.; Kaza, K. R. V.

1983-01-01

An improved finite difference procedure for determining the natural frequencies and mode shapes of tapered cantilever beams undergoing uncoupled vibrations is presented. Boundary conditions are derived in the form of simple recursive relations involving the second order central differences. Results obtained by using the conventional first order central differences and the present second order central differences are compared, and it is observed that the present second order scheme is more efficient than the conventional approach. An important advantage offered by the present approach is that the results converge to exact values rapidly, and thus the extrapolation of the results is not necessary. Consequently, the basic handicap with the classical finite difference method of solution that requires the Richardson's extrapolation procedure is eliminated. Furthermore, for the cases considered herein, the present approach produces consistent lower bound solutions.

Fiber-based monolithic columns for liquid chromatography.

PubMed

Ladisch, Michael; Zhang, Leyu

2016-10-01

Fiber-based monoliths for use in liquid chromatographic separations are defined by columns packed with aligned fibers, woven matrices, or contiguous fiber structures capable of achieving rapid separations of proteins, macromolecules, and low molecular weight components. A common denominator and motivating driver for this approach, first initiated 25 years ago, was reducing the cost of bioseparations in a manner that also reduced residence time of retained components while achieving a high ratio of mass to momentum transfer. This type of medium, when packed into a liquid chromatography column, minimized the fraction of stagnant liquid and resulted in a constant plate height for non-adsorbing species. The uncoupling of dispersion from eluent flow rate enabled the surface chemistry of the stationary phase to be considered separately from fluid transport phenomena and pointed to new ways to apply chemistry for the engineering of rapid bioseparations. This paper addresses developments and current research on fiber-based monoliths and explains how the various forms of this type of chromatographic stationary phase have potential to provide new tools for analytical and preparative scale separations. The different stationary phases are discussed, and a model that captures the observed constant plate height as a function of mobile phase velocity is reviewed. Methods that enable hydrodynamically stable fiber columns to be packed and operated over a range of mobile phase flow rates, together with the development of new fiber chemistries, are shown to provide columns that extend the versatility of liquid chromatography using monoliths, particularly at the preparative scale. Graphical Abstract Schematic representation of a sample mixture being separated by a rolled-stationary phase column, resulting separated peaks shown in the chromatogram.

Historical and projected carbon balance of mature black spruce ecosystems across north america: The role of carbon-nitrogen interactions

USGS Publications Warehouse

Clein, Joy S.; McGuire, A.D.; Zhang, X.; Kicklighter, D.W.; Melillo, J.M.; Wofsy, S.C.; Jarvis, P.G.; Massheder, J.M.

2002-01-01

The role of carbon (C) and nitrogen (N) interactions on sequestration of atmospheric CO2 in black spruce ecosystems across North America was evaluated with the Terrestrial Ecosystem Model (TEM) by applying parameterizations of the model in which C-N dynamics were either coupled or uncoupled. First, the performance of the parameterizations, which were developed for the dynamics of black spruce ecosystems at the Bonanza Creek Long-Term Ecological Research site in Alaska, were evaluated by simulating C dynamics at eddy correlation tower sites in the Boreal Ecosystem Atmosphere Study (BOREAS) for black spruce ecosystems in the northern study area (northern site) and the southern study area (southern site) with local climate data. We compared simulated monthly growing season (May to September) estimates of gross primary production (GPP), total ecosystem respiration (RESP), and net ecosystem production (NEP) from 1994 to 1997 to available field-based estimates at both sites. At the northern site, monthly growing season estimates of GPP and RESP for the coupled and uncoupled simulations were highly correlated with the field-based estimates (coupled: R2= 0.77, 0.88 for GPP and RESP; uncoupled: R2 = 0.67, 0.92 for GPP and RESP). Although the simulated seasonal pattern of NEP generally matched the field-based data, the correlations between field-based and simulated monthly growing season NEP were lower (R2 = 0.40, 0.00 for coupled and uncoupled simulations, respectively) in comparison to the correlations between field-based and simulated GPP and RESP. The annual NEP simulated by the coupled parameterization fell within the uncertainty of field-based estimates in two of three years. On the other hand, annual NEP simulated by the uncoupled parameterization only fell within the field-based uncertainty in one of three years. At the southern site, simulated NEP generally matched field-based NEP estimates, and the correlation between monthly growing season field-based and simulated NEP (R2 = 0.36, 0.20 for coupled and uncoupled simulations, respectively) was similar to the correlations at the northern site. To evaluate the role of N dynamics in C balance of black spruce ecosystems across North America, we simulated historical and projected C dynamics from 1900 to 2100 with a global-based climatology at 0.5?? resolution (latitude ?? longitude) with both the coupled and uncoupled parameterizations of TEM. From analyses at the northern site, several consistent patterns emerge. There was greater inter-annual variability in net primary production (NPP) simulated by the uncoupled parameterization as compared to the coupled parameterization, which led to substantial differences in inter-annual variability in NEP between the parameterizations. The divergence between NPP and heterotrophic respiration was greater in the uncoupled simulation, resulting in more C sequestration during the projected period. These responses were the result of fundamentally different responses of the coupled and uncoupled parameterizations to changes in CO2 and climate. Across North American black spruce ecosystems, the range of simulated decadal changes in C storage was substantially greater for the uncoupled parameterization than for the coupled parameterization. Analysis of the spatial variability in decadal responses of C dynamics revealed that C fluxes simulated by the coupled and uncoupled parameterizations have different sensitivities to climate and that the climate sensitivities of the fluxes change over the temporal scope of the simulations. The results of this study suggest that uncertainties can be reduced through (1) factorial studies focused on elucidating the role of C and N interactions in the response of mature black spruce ecosystems to manipulations of atmospheric CO2 and climate, (2) establishment of a network of continuous, long-term measurements of C dynamics across the range of mature black spruce ecosystems in North America, and (3) ancillary measureme

Adiabatic two-qubit state preparation in a superconducting qubit system

NASA Astrophysics Data System (ADS)

Filipp, Stefan; Ganzhorn, Marc; Egger, Daniel; Fuhrer, Andreas; Moll, Nikolaj; Mueller, Peter; Roth, Marco; Schmidt, Sebastian

The adiabatic transport of a quantum system from an initial eigenstate to its final state while remaining in the instantaneous eigenstate of the driving Hamiltonian can be used for robust state preparation. With control over both qubit frequencies and qubit-qubit couplings this method can be used to drive the system from initially trivial eigenstates of the uncoupled qubits to complex entangled multi-qubit states. In the context of quantum simulation, the final state may encode a non-trivial ground-state of a complex molecule or, in the context of adiabatic quantum computing, the solution to an optimization problem. Here, we present experimental results on a system comprising fixed-frequency superconducting transmon qubits and a tunable coupler to adjust the qubit-qubit coupling via parametric frequency modulation. We realize different types of interaction by adjusting the frequency of the modulation. A slow variation of drive amplitude and phase leads to an adiabatic steering of the system to its final state showing entanglement between the qubits.

Early Decrease in Respiration and Uncoupling Event Independent of Cytochrome c Release in PC12 Cells Undergoing Apoptosis

PubMed Central

Berghella, Libera; Ferraro, Elisabetta

2012-01-01

Cytochrome c is a key molecule in mitochondria-mediated apoptosis. It also plays a pivotal role in cell respiration. The switch between these two functions occurs at the moment of its release from mitochondria. This process is therefore extremely relevant for the fate of the cell. Since cytochrome c mediates respiration, we studied the changes in respiratory chain activity during the early stages of apoptosis in order to contribute to unravel the mechanisms of cytochrome c release. We found that, during staurosporine (STS)- induced apoptosis in PC12 cells, respiration is affected before the release of cytochrome c, as shown by a decrease in the endogenous uncoupled respiration and an uncoupling event, both occurring independently of cytochrome c release. The decline in the uncoupled respiration occurs also upon Bcl-2 overexpression (which inhibits cytochrome c release), while the uncoupling event is inhibited by Bcl-2. We also observed that the first stage of nuclear condensation during STS-induced apoptosis does not depend on the release of cytochrome c into the cytosol and is a reversibile event. These findings may contribute to understand the mechanisms affecting mitochondria during the early stages of apoptosis and priming them for the release of apoptogenic factors. PMID:22666257

Calorie restriction in mice overexpressing UCP3: evidence that prior mitochondrial uncoupling alters response.

PubMed

Estey, Carmen; Seifert, Erin L; Aguer, Céline; Moffat, Cynthia; Harper, Mary-Ellen

2012-05-01

Calorie restriction (CR) without malnutrition is the only intervention to consistently increase lifespan in all species tested, and lower age-related pathologies in mammals including humans. It has been suggested that uncoupling of mitochondrial oxidative phosphorylation, using chemical uncouplers, mimics CR, and that overlapping mechanisms underlie the phenotypic changes induced by uncoupling and CR. We aimed to critically assess this using a unique mouse model of skeletal muscle-targeted UCP3-induced uncoupling (UCP3Tg), and focused our studies mainly on skeletal muscle mitochondria. Compared to ad libitum fed Wt mice, skeletal muscle mitochondria from ad libitum fed UCP3Tg mice showed higher basal uncoupling and lower H(2)O(2) emission, with unchanged maximal oxidative phosphorylation, and mitochondrial content. UCP3Tg CR mice showed some tendency for differential adaptation to CR, with lowered H(+) leak conductance and evidence for higher H(2)O(2) emission from skeletal muscle mitochondria following 2 weeks CR, and failure to lower H(2)O(2) emission after 1 month CR. Differential adaptation was also apparent at the whole body level: while UCP3Tg CR mice lost as much weight as Wt CR mice, the proportion of muscle lost was higher in UCP3Tg mice. However, a striking outcome of our studies was the absence of change with CR in many of the parameters of mitochondrial function and content that we measured in mice of either genotype. Overall, our study raises the question of whether CR can consistently modify skeletal muscle mitochondria; alterations with CR may only be apparent under certain conditions such as during the 2 wk CR intervention in the UCP3Tg mice. Copyright © 2012 Elsevier Inc. All rights reserved.

SR4 Uncouples Mitochondrial Oxidative Phosphorylation, Modulates AMP-dependent Kinase (AMPK)-Mammalian Target of Rapamycin (mTOR) Signaling, and Inhibits Proliferation of HepG2 Hepatocarcinoma Cells*

PubMed Central

Figarola, James L.; Singhal, Jyotsana; Tompkins, Joshua D.; Rogers, George W.; Warden, Charles; Horne, David; Riggs, Arthur D.; Awasthi, Sanjay; Singhal, Sharad S.

2015-01-01

Mitochondrial oxidative phosphorylation produces most of the energy in aerobic cells by coupling respiration to the production of ATP. Mitochondrial uncouplers, which reduce the proton gradient across the mitochondrial inner membrane, create a futile cycle of nutrient oxidation without generating ATP. Regulation of mitochondrial dysfunction and associated cellular bioenergetics has been recently identified as a promising target for anticancer therapy. Here, we show that SR4 is a novel mitochondrial uncoupler that causes dose-dependent increase in mitochondrial respiration and dissipation of mitochondrial membrane potential in HepG2 hepatocarcinoma cells. These effects were reversed by the recoupling agent 6-ketocholestanol but not cyclosporin A and were nonexistent in mitochondrial DNA-depleted HepG2 cells. In isolated mouse liver mitochondria, SR4 similarly increased oxygen consumption independent of adenine nucleotide translocase and uncoupling proteins, decreased mitochondrial membrane potential, and promoted swelling of valinomycin-treated mitochondria in potassium acetate medium. Mitochondrial uncoupling in HepG2 cells by SR4 results in the reduction of cellular ATP production, increased ROS production, activation of the energy-sensing enzyme AMPK, and inhibition of acetyl-CoA carboxylase and mammalian target of rapamycin signaling pathways, leading to cell cycle arrest and apoptosis. Global analysis of SR4-associated differential gene expression confirms these observations, including significant induction of apoptotic genes and down-regulation of cell cycle, mitochondrial, and oxidative phosphorylation pathway transcripts at 24 h post-treatment. Collectively, our studies demonstrate that the previously reported indirect activation of AMPK and in vitro anticancer properties of SR4 as well as its beneficial effects in both animal xenograft and obese mice models could be a direct consequence of its mitochondrial uncoupling activity. PMID:26534958

Calorie restriction in mice overexpressing UCP3: evidence that prior mitochondrial uncoupling alters response

PubMed Central

Estey, Carmen; Seifert, Erin L.; Aguer, Céline; Moffat, Cynthia; Harper, Mary-Ellen

2012-01-01

SUMMARY Calorie restriction (CR) without malnutrition is the only intervention to consistently increase lifespan in all species tested, and lower age-related pathologies in mammals including humans. It has been suggested that uncoupling of mitochondrial oxidative phosphorylation, using chemical uncouplers, mimics CR, and that overlapping mechanisms underlie the phenotypic changes induced by uncoupling and CR. We aimed to critically assess this using a unique mouse model of skeletal muscle-targeted UCP3-induced uncoupling (UCP3Tg), and focused our studies mainly on skeletal muscle mitochondria. Compared to ad libitum fed Wt mice, skeletal muscle mitochondria from ad libitum fed UCP3Tg mice showed higher basal uncoupling and lower H2O2 emission, with unchanged maximal oxidative phosphorylation, and mitochondrial content. UCP3Tg CR mice showed some tendency for differential adaptation to CR, with lowered H+ leak conductance and evidence for higher H2O2 emission from skeletal muscle mitochondria following 2 weeks CR, and failure to lower H2O2 emission after 1 month CR. Differential adaptation was also apparent at the whole body level: while UCP3Tg CR mice lost as much weight as Wt CR mice, the proportion of muscle lost was higher in UCP3Tg mice. However, a striking outcome of our studies was the absence of change with CR in many of the parameters of mitochondrial function and content that we measured in mice of either genotype. Overall, our study raises the question of whether CR can consistently modify skeletal muscle mitochondria; alterations with CR may only be apparent under certain conditions such as during the 2 wk CR intervention in the UCP3Tg mice. PMID:22406134

Exact Solutions of Coupled Multispecies Linear Reaction–Diffusion Equations on a Uniformly Growing Domain

PubMed Central

Simpson, Matthew J.; Sharp, Jesse A.; Morrow, Liam C.; Baker, Ruth E.

2015-01-01

Embryonic development involves diffusion and proliferation of cells, as well as diffusion and reaction of molecules, within growing tissues. Mathematical models of these processes often involve reaction–diffusion equations on growing domains that have been primarily studied using approximate numerical solutions. Recently, we have shown how to obtain an exact solution to a single, uncoupled, linear reaction–diffusion equation on a growing domain, 0 < x < L(t), where L(t) is the domain length. The present work is an extension of our previous study, and we illustrate how to solve a system of coupled reaction–diffusion equations on a growing domain. This system of equations can be used to study the spatial and temporal distributions of different generations of cells within a population that diffuses and proliferates within a growing tissue. The exact solution is obtained by applying an uncoupling transformation, and the uncoupled equations are solved separately before applying the inverse uncoupling transformation to give the coupled solution. We present several example calculations to illustrate different types of behaviour. The first example calculation corresponds to a situation where the initially–confined population diffuses sufficiently slowly that it is unable to reach the moving boundary at x = L(t). In contrast, the second example calculation corresponds to a situation where the initially–confined population is able to overcome the domain growth and reach the moving boundary at x = L(t). In its basic format, the uncoupling transformation at first appears to be restricted to deal only with the case where each generation of cells has a distinct proliferation rate. However, we also demonstrate how the uncoupling transformation can be used when each generation has the same proliferation rate by evaluating the exact solutions as an appropriate limit. PMID:26407013

Exact Solutions of Coupled Multispecies Linear Reaction-Diffusion Equations on a Uniformly Growing Domain.

PubMed

Simpson, Matthew J; Sharp, Jesse A; Morrow, Liam C; Baker, Ruth E

2015-01-01

Embryonic development involves diffusion and proliferation of cells, as well as diffusion and reaction of molecules, within growing tissues. Mathematical models of these processes often involve reaction-diffusion equations on growing domains that have been primarily studied using approximate numerical solutions. Recently, we have shown how to obtain an exact solution to a single, uncoupled, linear reaction-diffusion equation on a growing domain, 0 < x < L(t), where L(t) is the domain length. The present work is an extension of our previous study, and we illustrate how to solve a system of coupled reaction-diffusion equations on a growing domain. This system of equations can be used to study the spatial and temporal distributions of different generations of cells within a population that diffuses and proliferates within a growing tissue. The exact solution is obtained by applying an uncoupling transformation, and the uncoupled equations are solved separately before applying the inverse uncoupling transformation to give the coupled solution. We present several example calculations to illustrate different types of behaviour. The first example calculation corresponds to a situation where the initially-confined population diffuses sufficiently slowly that it is unable to reach the moving boundary at x = L(t). In contrast, the second example calculation corresponds to a situation where the initially-confined population is able to overcome the domain growth and reach the moving boundary at x = L(t). In its basic format, the uncoupling transformation at first appears to be restricted to deal only with the case where each generation of cells has a distinct proliferation rate. However, we also demonstrate how the uncoupling transformation can be used when each generation has the same proliferation rate by evaluating the exact solutions as an appropriate limit.

TRP channels in brown and white adipogenesis from human progenitors: new therapeutic targets and the caveats associated with the common antibiotic, streptomycin.

PubMed

Goralczyk, Anna; van Vijven, Marc; Koch, Mathilde; Badowski, Cedric; Yassin, M Shabeer; Toh, Sue-Anne; Shabbir, Asim; Franco-Obregón, Alfredo; Raghunath, Michael

2017-08-01

Transient receptor potential (TRP) channels are polymodal cell sensors responding to diverse stimuli and widely implicated in the developmental programs of numerous tissues. The evidence for an involvement of TRP family members in adipogenesis, however, is scant. We present the first comprehensive expression profile of all known 27 human TRP genes in mesenchymal progenitors cells during white or brown adipogenesis. Using positive trilineage differentiation as an exclusion criterion, TRP polycystic (P)3, and TPR melastatin (M)8 were found to be uniquely adipospecific. Knockdown of TRPP3 repressed the expression of the brown fat signature genes uncoupling protein (UCP)-1 and peroxisome proliferator-activated receptor γ coactivator (PGC)-1α as well as attenuated forskolin-stimulated uncoupled respiration. However, indices of generalized adipogenesis, such as lipid droplet morphology and fatty acid binding protein (FAPB)-4 expression, were not affected, indicating a principal mitochondrial role of TRPP3. Conversely, activating TRPM8 with menthol up-regulated UCP-1 expression and augmented uncoupled respiration predominantly in white adipocytes (browning), whereas streptomycin antagonized TRPM8-mediated calcium entry, downregulated UCP-1 expression, and mitigated uncoupled respiration; menthol was less capable of augmenting uncoupled respiration (thermogenesis) in brown adipocytes. TRPP3 and TRPM8 hence appear to be involved in the priming of mitochondria to perform uncoupled respiration downstream of adenylate cyclase. Our results also underscore the developmental caveats of using antibiotics in adipogenic studies.-Goralczyk, A., van Vijven, M., Koch, M., Badowski, C., Yassin, M. S., Toh, S.-A., Shabbir, A., Franco-Obregón, A., Raghunath, M. TRP channels in brown and white adipogenesis from human progenitors: new therapeutic targets and the caveats associated with the common antibiotic, streptomycin. © FASEB.

Chronic mitochondrial uncoupling treatment prevents acute cold-induced oxidative stress in birds.

PubMed

Stier, Antoine; Massemin, Sylvie; Criscuolo, François

2014-12-01

Endotherms have evolved two major types of thermogenesis that allow them to actively produce heat in response to cold exposure, either through muscular activity (i.e. shivering thermogenesis) or through futile electro-chemical cycles (i.e. non-shivering thermogenesis). Amongst the latter, mitochondrial uncoupling is of key importance because it is suggested to drive heat production at a low cost in terms of oxidative stress. While this has been experimentally shown in mammals, the oxidative stress consequences of cold exposure and mitochondrial uncoupling are clearly less understood in the other class of endotherms, the birds. We compared metabolic and oxidative stress responses of zebra finches chronically treated with or without a chemical mitochondrial uncoupler (2,4-dinitrophenol: DNP), undergoing an acute (24 h) and a chronic (4 weeks) cold exposure (12 °C). We predicted that control birds should present at least a transient elevation of oxidative stress levels in response to cold exposure. This oxidative stress cost should be more pronounced in control birds than in DNP-treated birds, due to their lower basal uncoupling state. Despite similar increase in metabolism, control birds presented elevated levels of DNA oxidative damage in response to acute (but not chronic) cold exposure, while DNP-treated birds did not. Plasma antioxidant capacity decreased overall in response to chronic cold exposure. These results show that acute cold exposure increases oxidative stress in birds. However, uncoupling mitochondrial functioning appears as a putative compensatory mechanism preventing cold-induced oxidative stress. This result confirms previous observations in mice and underlines non-shivering thermogenesis as a putative key mechanism for endotherms in mounting a response to cold at a low oxidative cost.

Measuring mitochondrial uncoupling protein-2 level and activity in insulinoma cells.

PubMed

Barlow, Jonathan; Hirschberg, Verena; Brand, Martin D; Affourtit, Charles

2013-01-01

Mitochondrial uncoupling protein-2 (UCP2) regulates glucose-stimulated insulin secretion (GSIS) by pancreatic beta cells-the physiological role of the beta cell UCP2 remains a subject of debate. Experimental studies informing this debate benefit from reliable measurements of UCP2 protein level and activity. In this chapter, we describe how UCP2 protein can be detected in INS-1 insulinoma cells and how it can be knocked down by RNA interference. We demonstrate briefly that UCP2 knockdown lowers glucose-induced rises in mitochondrial respiratory activity, coupling efficiency of oxidative phosphorylation, levels of mitochondrial reactive oxygen species, and insulin secretion. We provide protocols for the detection of the respective UCP2 phenotypes, which are indirect, but invaluable measures of UCP2 activity. We also introduce a convenient method to normalize cellular respiration to cell density allowing measurement of UCP2 effects on specific mitochondrial oxygen consumption. Copyright © 2013 Elsevier Inc. All rights reserved.

Sequence-dependent nucleosome sliding in rotation-coupled and uncoupled modes revealed by molecular simulations

PubMed Central

Tan, Cheng; Takada, Shoji

2017-01-01

While nucleosome positioning on eukaryotic genome play important roles for genetic regulation, molecular mechanisms of nucleosome positioning and sliding along DNA are not well understood. Here we investigated thermally-activated spontaneous nucleosome sliding mechanisms developing and applying a coarse-grained molecular simulation method that incorporates both long-range electrostatic and short-range hydrogen-bond interactions between histone octamer and DNA. The simulations revealed two distinct sliding modes depending on the nucleosomal DNA sequence. A uniform DNA sequence showed frequent sliding with one base pair step in a rotation-coupled manner, akin to screw-like motions. On the contrary, a strong positioning sequence, the so-called 601 sequence, exhibits rare, abrupt transitions of five and ten base pair steps without rotation. Moreover, we evaluated the importance of hydrogen bond interactions on the sliding mode, finding that strong and weak bonds favor respectively the rotation-coupled and -uncoupled sliding movements. PMID:29194442

Snf1-related kinase improves cardiac mitochondrial efficiency and decreases mitochondrial uncoupling

PubMed Central

Rines, Amy K.; Chang, Hsiang-Chun; Wu, Rongxue; Sato, Tatsuya; Khechaduri, Arineh; Kouzu, Hidemichi; Shapiro, Jason; Shang, Meng; Burke, Michael A.; Abdelwahid, Eltyeb; Jiang, Xinghang; Chen, Chunlei; Rawlings, Tenley A.; Lopaschuk, Gary D.; Schumacker, Paul T.; Abel, E. Dale; Ardehali, Hossein

2017-01-01

Ischaemic heart disease limits oxygen and metabolic substrate availability to the heart, resulting in tissue death. Here, we demonstrate that the AMP-activated protein kinase (AMPK)-related protein Snf1-related kinase (SNRK) decreases cardiac metabolic substrate usage and mitochondrial uncoupling, and protects against ischaemia/reperfusion. Hearts from transgenic mice overexpressing SNRK have decreased glucose and palmitate metabolism and oxygen consumption, but maintained power and function. They also exhibit decreased uncoupling protein 3 (UCP3) and mitochondrial uncoupling. Conversely, Snrk knockout mouse hearts have increased glucose and palmitate oxidation and UCP3. SNRK knockdown in cardiac cells decreases mitochondrial efficiency, which is abolished with UCP3 knockdown. We show that Tribbles homologue 3 (Trib3) binds to SNRK, and downregulates UCP3 through PPARα. Finally, SNRK is increased in cardiomyopathy patients, and SNRK reduces infarct size after ischaemia/reperfusion. SNRK also decreases cardiac cell death in a UCP3-dependent manner. Our results suggest that SNRK improves cardiac mitochondrial efficiency and ischaemic protection. PMID:28117339

The on/off switches of the mitochondrial uncoupling proteins

PubMed Central

Azzu, Vian; Brand, Martin D.

2013-01-01

Mitochondrial uncoupling proteins disengage substrate oxidation from ADP phosphorylation by dissipating the proton electrochemical gradient that is required for ATP synthesis. In doing this, the archetypal uncoupling protein, UCP1, mediates adaptive thermogenesis. By contrast, its paralogues UCP2 and UCP3 are not thought to mediate whole body thermogenesis in mammals. Instead, they have been implicated in a variety of physiological and pathological processes, including protection from oxidative stress, negative regulation of glucose sensing systems and the adaptation of fatty acid oxidation capacity to starving. Although much work has been devoted to how these proteins are activated, little is known of the mechanisms that reverse this activation. PMID:20006514

Dual Role of Endothelial Nitric Oxide Synthase in Oxidized LDL-Induced, p66Shc-Mediated Oxidative Stress in Cultured Human Endothelial Cells

PubMed Central

Shi, Yi; Lüscher, Thomas F.; Camici, Giovanni G.

2014-01-01

Background The aging gene p66Shc, is an important mediator of oxidative stress-induced vascular dysfunction and disease. In cultured human aortic endothelial cells (HAEC), p66Shc deletion increases endothelial nitric oxide synthase (eNOS) expression and nitric oxide (NO) bioavailability via protein kinase B. However, the putative role of the NO pathway on p66Shc activation remains unclear. This study was designed to elucidate the regulatory role of the eNOS/NO pathway on p66Shc activation. Methods and Results Incubation of HAEC with oxidized low density lipoprotein (oxLDL) led to phosphorylation of p66Shc at Ser-36, resulting in an enhanced production of superoxide anion (O2 -). In the absence of oxLDL, inhibition of eNOS by small interfering RNA or L-NAME, induced p66Shc phosphorylation, suggesting that basal NO production inhibits O2 - production. oxLDL-induced, p66Shc-mediated O2- was prevented by eNOS inhibition, suggesting that when cells are stimulated with oxLDL eNOS is a source of reactive oxygen species. Endogenous or exogenous NO donors, prevented p66Shc activation and reduced O2- production. Treatment with tetrahydrobiopterin, an eNOS cofactor, restored eNOS uncoupling, prevented p66Shc activation, and reduced O2- generation. However, late treatment with tetrahydropterin did not yield the same result suggesting that eNOS uncoupling is the primary source of reactive oxygen species. Conclusions The present study reports that in primary cultured HAEC treated with oxLDL, p66Shc-mediated oxidative stress is derived from eNOS uncoupling. This finding contributes novel information on the mechanisms of p66Shc activation and its dual interaction with eNOS underscoring the importance eNOS uncoupling as a putative antioxidant therapeutical target in endothelial dysfunction as observed in cardiovascular disease. PMID:25247687

Novel browning agents, mechanisms and therapeutic potentials of brown adipose tissue

USDA-ARS?s Scientific Manuscript database

Non-shivering thermogenesis is the process of biological heat production in mammals and is primarily mediated by brown adipose tissue (BAT). Through ubiquitous expression of uncoupling protein 1 (Ucp1) on the mitochondrial inner membrane, BAT displays uncoupling of fuel combustion and ATP production...

Salvianolic acid A inhibits calpain activation and eNOS uncoupling during focal cerebral ischemia in mice.

PubMed

Mahmood, Qaisar; Wang, Guang-Fa; Wu, Gang; Wang, Huan; Zhou, Chang-Xin; Yang, Hong-Yu; Liu, Zhi-Rong; Han, Feng; Zhao, Kui

2017-02-15

Salvianolic acid A (SAA) is obtained from Chinese herb Salviae Miltiorrhizae Bunge (Labiatae), has been reported to have the protective effects against cardiovascular and neurovascular diseases. The aim of present study was to investigate the relationship between the effectiveness of SAA against neurovascular injury and its effects on calpain activation and endothelial nitric oxide synthase (eNOS) uncoupling. SAA or vehicle was given to C57BL/6 male mice for seven days before the occlusion of middle cerebral artery (MCAO) for 60min. High-resolution positron emission tomography scanner (micro-PET) was used for small animal imaging to examine glucose metabolism. Rota-rod time and neurological deficit scores were calculated after 24h of reperfusion. The volume of infarction was determined by Nissl-staining. The calpain proteolytic activity and eNOS uncoupling were determined by western blot analysis. SAA administration increased glucose metabolism and ameliorated neuronal damage after brain ischemia, paralleled with decreased neurological deficit and volume of infarction. In addition, SAA pretreatment inhibited eNOS uncoupling and calpain proteolytic activity. Furthermore, SAA inhibited peroxynitrite (ONOO - ) generation and upregulates AKT, FKHR and ERK phosphorylation. These findings strongly suggest that SAA elicits a neurovascular protective role through the inhibition of eNOS uncoupling and ONOO - formation. Moreover, SAA attenuates spectrin and calcineurin breakdown and therefore protects the brain against ischemic/reperfusion injury. Copyright © 2016 Elsevier GmbH. All rights reserved.

Modular architecture for robotics and teleoperation

DOEpatents

Anderson, Robert J.

1996-12-03

Systems and methods for modularization and discretization of real-time robot, telerobot and teleoperation systems using passive, network based control laws. Modules consist of network one-ports and two-ports. Wave variables and position information are passed between modules. The behavior of each module is decomposed into uncoupled linear-time-invariant, and coupled, nonlinear memoryless elements and then are separately discretized.

Imaging separation of neuronal from vascular effects of cocaine on rat cortical brain in vivo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yuan, Z.; Du, C.; Yuan, Z.

MRI techniques to study brain function assume coupling between neuronal activity, metabolism and flow. However, recent evidence of physiological uncoupling between neuronal and cerebrovascular events highlights the need for methods to simultaneously measure these three properties. We report a multimodality optical approach that integrates dual-wavelength laser speckle imaging (measures changes in blood flow, blood volume and hemoglobin oxygenation), digital-frequency-ramping optical coherence tomography (images quantitative 3D vascular network) and Rhod2 fluorescence (images intracellular calcium for measure of neuronal activity) at high spatiotemporal resolutions (30 {micro}m, 10 Hz) and over a large field of view (3 x 5 mm{sup 2}). We applymore » it to assess cocaine's effects in rat cortical brain and show an immediate decrease 3.5 {+-} 0.9 min, phase (1) in the oxygen content of hemoglobin and the cerebral blood flow followed by an overshoot 7.1 {+-} 0.2 min, phase (2) lasting over 20 min whereas Ca{sup 2+} increased immediately (peaked at t = 4.1 {+-} 0.4 min) and remained elevated. This enabled us to identify a delay (2.9 {+-} 0.5 min) between peak neuronal and vascular responses in phase 2. The ability of this multimodality optical approach for simultaneous imaging at high spatiotemporal resolutions permits us to distinguish the vascular versus cellular changes of the brain, thus complimenting other neuroimaging modalities for brain functional studies (e. g., PET, fMRI).« less

Bleustein-Gulyaev wave propagation characteristics in KNbO3 and PKN crystals

NASA Astrophysics Data System (ADS)

Dvoesherstov, M. Y.; Cherednick, V. I.; Chirimanov, A. P.; Petrov, S. G.

1999-09-01

In this paper, theoretical investigation is shown for cuts and propagation directions on KNbO3, PKN substrates where the Bleustein-Gulyaev waves exist. The KNbO3 and PKN crystals Y-cut X-propagating relate to the condition in which the stiffened shear horizontal wave and pure mechanical Rayleigh wave are present. In this symmetry orientation the sagittal and transverse particle displacements also uncouple. In this situation, the potential is coupled to the shear horizontal displacements only. Electromechanical coupling coefficients K2 has a sufficiently large value of above 53 percent with a phase velocity of V equals 3.918 km/s for KNbO3 crystals and factor K2 has a large value of above 23.6 percent and phase velocity V equals 3.054 km/s for PKN crystals.

Rapid DNA replication origin licensing protects stem cell pluripotency

PubMed Central

Matson, Jacob Peter; Dumitru, Raluca; Coryell, Philip; Baxley, Ryan M; Chen, Weili; Twaroski, Kirk; Webber, Beau R; Tolar, Jakub; Bielinsky, Anja-Katrin; Purvis, Jeremy E

2017-01-01

Complete and robust human genome duplication requires loading minichromosome maintenance (MCM) helicase complexes at many DNA replication origins, an essential process termed origin licensing. Licensing is restricted to G1 phase of the cell cycle, but G1 length varies widely among cell types. Using quantitative single-cell analyses, we found that pluripotent stem cells with naturally short G1 phases load MCM much faster than their isogenic differentiated counterparts with long G1 phases. During the earliest stages of differentiation toward all lineages, MCM loading slows concurrently with G1 lengthening, revealing developmental control of MCM loading. In contrast, ectopic Cyclin E overproduction uncouples short G1 from fast MCM loading. Rapid licensing in stem cells is caused by accumulation of the MCM loading protein, Cdt1. Prematurely slowing MCM loading in pluripotent cells not only lengthens G1 but also accelerates differentiation. Thus, rapid origin licensing is an intrinsic characteristic of stem cells that contributes to pluripotency maintenance. PMID:29148972

A novel amino acid and metabolomics signature in mice overexpressing muscle uncoupling protein 3

USDA-ARS?s Scientific Manuscript database

Uncoupling protein 3 (UCP3) is highly expressed in skeletal muscle and is known to lower mitochondrial reactive oxygen species and promote fatty acid oxidation; however, the global impact of UCP3 activity on skeletal muscle and whole body metabolism has not been extensively studied. We utilized unt...

MTORC1 Regulates both General Autophagy and Mitophagy Induction after Oxidative Phosphorylation Uncoupling.

PubMed

Bartolomé, Alberto; García-Aguilar, Ana; Asahara, Shun-Ichiro; Kido, Yoshiaki; Guillén, Carlos; Pajvani, Utpal B; Benito, Manuel

2017-09-11

The mechanistic target of rapamycin complex 1 (MTORC1) is a critical negative regulator of general autophagy. We hypothesized that MTORC1 may specifically regulate autophagic clearance of damaged mitochondria. To test this, we used cells lacking tuberous sclerosis complex 2 (TSC2 -/-), which show constitutive MTORC1 activation. TSC2 -/- cells show MTORC1-dependent impaired autophagic flux after chemical uncoupling of mitochondria, increased mitochondrial protein aging and accumulation of p62/SQSTM1 positive mitochondria. Mitochondrial autophagy (mitophagy) was also deficient in cells lacking TSC2, associated with altered expression of PTEN-induced kinase 1 (PINK1) and PARK2 translocation to uncoupled mitochondria, all of which were recovered by MTORC1 inhibition or expression of constitutively active FoxO1. These data prove the necessity of intact MTORC1 signaling to regulate two synergistic processes required for clearance of damaged mitochondria: 1) general autophagy initiation, and 2) PINK1/PARK2-mediated selective targeting of uncoupled mitochondria to the autophagic machinery. Copyright © 2017 American Society for Microbiology.

Carbon Tetrachloride at Hepatotoxic Levels Blocks Reversibly Gap Junctions between Rat Hepatocytes

NASA Astrophysics Data System (ADS)

Saez, J. C.; Bennett, M. V. L.; Spray, D. C.

1987-05-01

Electrical coupling and dye coupling between pairs of rat hepatocytes were reversibly reduced by brief exposure to halogenated methanes (CBrCl3, CCl4, and CHCl3). The potency of different halomethanes in uncoupling hepatocytes was comparable to their hepatotoxicity in vivo, and the rank order was the same as that of their tendency to form free radicals. The effect of carbon tetrachloride (CCl4) on hepatocytes was substantially reduced by prior treatment with SKF 525A, an inhibitor of cytochrome P-450, and by exposure to the reducing reagent β -mercaptoethanol. Halomethane uncoupling occurred with or without extracellular calcium and did not change intracellular concentrations of calcium and hydrogen ions or the phosphorylation state of the main gap-junctional protein. Thus the uncoupling appears to depend on cytochrome P-450 oxidative metabolism in which free radicals are generated and may result from oxidation of the gap-junctional protein or of a regulatory molecule that leads to closure of gap-junctional channels. Decreases in junctional conductance may be a rapid cellular response to injury that protects healthy cells by uncoupling them from unhealthy ones.

Nitric oxide, PKC-ε, and connexin43 are crucial for ischemic preconditioning-induced chemical gap junction uncoupling.

PubMed

Rong, Bing; Xie, Fei; Sun, Tao; Hao, Li; Lin, Ming-Jie; Zhong, Jing-Quan

2016-10-25

Ischemic preconditioning (IPC) maintains connexin43 (Cx43) phosphorylation and reduces chemical gap junction (GJ) coupling in cardiomyocytes to protect against ischemic damage. However, the signal transduction pathways underlying these effects are not fully understood. Here, we investigated whether nitric oxide (NO) and protein kinase C-ε (PKC-ε) contribute to IPC-induced cardioprotection by maintaining Cx43 phosphorylation and inhibiting chemical GJ coupling. IPC reduced ischemia-induced myocardial infarction and increased cardiomyocyte survival; phosphorylated Cx43, eNOS, and PKC-ε levels; and chemical GJ uncoupling. Administration of the NO donor SNAP mimicked the effects of IPC both in vivo and in vitro, maintaining Cx43 phosphorylation, promoting chemical GJ uncoupling, and reducing myocardial infarction. Preincubation with the NO synthase inhibitor L-NAME or PKC-ε translocation inhibitory peptide (PKC-ε-TIP) abolished these effects of IPC. Additionally, by inducing NO production, IPC induced translocation of PKC-ε, but not PKC-δ, from the cytosolic to the membrane fraction in primary cardiac myocytes. IPC-induced cardioprotection thus involves increased NO production, PKC-ε translocation, Cx43 phosphorylation, and chemical GJ uncoupling.

Skeletal muscle respiratory uncoupling prevents diet-induced obesity and insulin resistance in mice.

PubMed

Li, B; Nolte, L A; Ju, J S; Han, D H; Coleman, T; Holloszy, J O; Semenkovich, C F

2000-10-01

To determine whether uncoupling respiration from oxidative phosphorylation in skeletal muscle is a suitable treatment for obesity and type 2 diabetes, we generated transgenic mice expressing the mitochondrial uncoupling protein (Ucp) in skeletal muscle. Skeletal muscle oxygen consumption was 98% higher in Ucp-L mice (with low expression) and 246% higher in Ucp-H mice (with high expression) than in wild-type mice. Ucp mice fed a chow diet had the same food intake as wild-type mice, but weighed less and had lower levels of glucose and triglycerides and better glucose tolerance than did control mice. Ucp-L mice were resistant to obesity induced by two different high-fat diets. Ucp-L mice fed a high-fat diet had less adiposity, lower levels of glucose, insulin and cholesterol, and an increased metabolic rate at rest and with exercise. They were also more responsive to insulin, and had enhanced glucose transport in skeletal muscle in the setting of increased muscle triglyceride content. These data suggest that manipulating respiratory uncoupling in muscle is a viable treatment for obesity and its metabolic sequelae.

Muscle Mitochondrial Uncoupling Dismantles Neuromuscular Junction and Triggers Distal Degeneration of Motor Neurons

PubMed Central

Dupuis, Luc; Gonzalez de Aguilar, Jose-Luis; Echaniz-Laguna, Andoni; Eschbach, Judith; Rene, Frédérique; Oudart, Hugues; Halter, Benoit; Huze, Caroline; Schaeffer, Laurent; Bouillaud, Frédéric; Loeffler, Jean-Philippe

2009-01-01

Background Amyotrophic lateral sclerosis (ALS), the most frequent adult onset motor neuron disease, is associated with hypermetabolism linked to defects in muscle mitochondrial energy metabolism such as ATP depletion and increased oxygen consumption. It remains unknown whether muscle abnormalities in energy metabolism are causally involved in the destruction of neuromuscular junction (NMJ) and subsequent motor neuron degeneration during ALS. Methodology/Principal Findings We studied transgenic mice with muscular overexpression of uncoupling protein 1 (UCP1), a potent mitochondrial uncoupler, as a model of muscle restricted hypermetabolism. These animals displayed age-dependent deterioration of the NMJ that correlated with progressive signs of denervation and a mild late-onset motor neuron pathology. NMJ regeneration and functional recovery were profoundly delayed following injury of the sciatic nerve and muscle mitochondrial uncoupling exacerbated the pathology of an ALS animal model. Conclusions/Significance These findings provide the proof of principle that a muscle restricted mitochondrial defect is sufficient to generate motor neuron degeneration and suggest that therapeutic strategies targeted at muscle metabolism might prove useful for motor neuron diseases. PMID:19404401

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Kun; Sun, Guoxun; Lv, Zhiyuan

Research highlights: {yields} Invertebrates, for example amphioxus, do express uncoupling proteins. {yields} Both the sequence and the uncoupling activity of amphioxus UCP resemble UCP2. {yields} UCP1 is the only UCP that can form dimer on yeast mitochondria. -- Abstract: The present study describes the molecular cloning of a novel cDNA fragment from amphioxus (Branchiostoma belcheri) encoding a 343-amino acid protein that is highly homologous to human uncoupling proteins (UCP), this protein is therefore named amphioxus UCP. This amphioxus UCP shares more homology with and is phylogenetically more related to mammalian UCP2 as compared with UCP1. To further assess the functionalmore » similarity of amphioxus UCP to mammalian UCP1 and -2, the amphioxus UCP, rat UCP1, and human UCP2 were separately expressed in Saccharomyces cerevisiae, and the recombinant yeast mitochondria were isolated and assayed for the state 4 respiration rate and proton leak, using pYES2 empty vector as the control. UCP1 increased the state 4 respiration rate by 2.8-fold, and the uncoupling activity was strongly inhibited by GDP, while UCP2 and amphioxus UCP only increased the state 4 respiration rate by 1.5-fold and 1.7-fold in a GDP-insensitive manner, moreover, the proton leak kinetics of amphioxus UCP was very similar to UCP2, but much different from UCP1. In conclusion, the amphioxus UCP has a mild, unregulated uncoupling activity in the yeast system, which resembles mammalian UCP2, but not UCP1.« less

Protective effect of metronidazole on uncoupling mitochondrial oxidative phosphorylation induced by NSAID: a new mechanism.

PubMed

Leite, A Z; Sipahi, A M; Damião, A O; Coelho, A M; Garcez, A T; Machado, M C; Buchpiguel, C A; Lopasso, F P; Lordello, M L; Agostinho, C L; Laudanna, A A

2001-02-01

The pathogenesis of non-steroidal anti-inflammatory drug (NSAID) enteropathy is complex. It involves uncoupling of mitochondrial oxidative phosphorylation which alters the intercellular junction and increases intestinal permeability with consequent intestinal damage. Metronidazole diminishes the inflammation induced by indomethacin but the mechanisms remain speculative. A direct effect on luminal bacteria has traditionally been thought to account for the protective effect of metronidazole. However, a protective effect of metronidazole on mitochondrial oxidative phosphorylation has never been tested. To assess the protective effect of metronidazole on mitochondrial uncoupling induced by indomethacin and also on the increased intestinal permeability and macroscopic damage. The protective effect of metronidazole was evaluated in rats given indomethacin; a macroscopic score was devised to quantify intestinal lesions, and intestinal permeability was measured by means of (51)Cr-ethylenediaminetetraacetic acid. The protective effect of metronidazole against mitochondrial uncoupling induced by indomethacin was assessed using isolated coupled rat liver mitochondria obtained from rats pretreated with metronidazole or saline. Metronidazole significantly reduced the macroscopic intestinal damage and increase in intestinal permeability induced by indomethacin; furthermore, at the mitochondrial level, it significantly reduced the increase in oxygen consumption in state 4 induced by indomethacin and caused less reduction of the respiratory control rate. Our study confirmed the beneficial effects of metronidazole on intestinal damage and intestinal permeability, and demonstrated, for the first time, a direct protective effect of metronidazole on uncoupling of mitochondrial oxidative phosphorylation caused by NSAIDs.

Mitochondrial uncoupling, ROS generation and cardioprotection.

PubMed

Cadenas, Susana

2018-05-31

Mitochondrial oxidative phosphorylation is incompletely coupled, since protons translocated to the intermembrane space by specific respiratory complexes of the electron transport chain can return to the mitochondrial matrix independently of the ATP synthase -a process known as proton leak- generating heat instead of ATP. Proton leak across the inner mitochondrial membrane increases the respiration rate and decreases the electrochemical proton gradient (Δp), and is an important mechanism for energy dissipation that accounts for up to 25% of the basal metabolic rate. It is well established that mitochondrial superoxide production is steeply dependent on Δp in isolated mitochondria and, correspondingly, mitochondrial uncoupling has been identified as a cytoprotective strategy under conditions of oxidative stress, including diabetes, drug-resistance in tumor cells, ischemia-reperfusion (IR) injury or aging. Mitochondrial uncoupling proteins (UCPs) are able to lower the efficiency of oxidative phosphorylation and are involved in the control of mitochondrial reactive oxygen species (ROS) production. There is strong evidence that UCP2 and UCP3, the UCP1 homologues expressed in the heart, protect against mitochondrial oxidative damage by reducing the production of ROS. This review first analyzes the relationship between mitochondrial proton leak and ROS generation, and then focuses on the cardioprotective role of chemical uncoupling and uncoupling mediated by UCPs. This includes their protective effects against cardiac IR, a condition known to increase ROS production, and their roles in modulating cardiovascular risk factors such as obesity, diabetes and atherosclerosis. Copyright © 2018. Published by Elsevier B.V.

Temperature dependence of rat liver mitochondrial respiration with uncoupling of oxidative phosphorylation by fatty acids. Influence of inorganic phosphate.

PubMed

Samartsev, V N; Chezganova, S A; Polishchuk, L S; Paydyganov, A P; Vidyakina, O V; Zeldi, I P

2003-06-01

The respiration rate of liver mitochondria in the course of succinate oxidation depends on temperature in the presence of palmitate more strongly than in its absence (in state 4). In the Arrhenius plot, the temperature dependence of the palmitate-induced stimulation of respiration has a bend at 22 degrees C which is characterized by transition of the activation energy from 120 to 60 kJ/mol. However, a similar dependence of respiration in state 4 is linear over the whole temperature range and corresponds to the activation energy of 17 kJ/mol. Phosphate partially inhibits the uncoupling effect of palmitate. This effect of phosphate is increased on decrease in temperature. In the presence of phosphate the temperature dependence in the Arrhenius plot also has a bend at 22 degrees C, and the activation energy increases from 128 to 208 kJ/mol in the range from 13 to 22 degrees C and from 56 to 67 kJ/mol in the range from 22 to 37 degrees C. Mersalyl (10 nmol/mg protein), an inhibitor of the phosphate carrier, similarly to phosphate, suppresses the uncoupling effect of laurate, and the effects of mersalyl and phosphate are not additive. The recoupling effects of phosphate and mersalyl seem to show involvement of the phosphate carrier in the uncoupling effect of fatty acids in liver mitochondria. Possible mechanisms of involvement of the phosphate carrier in the uncoupling effect of fatty acids are discussed.

SR4 Uncouples Mitochondrial Oxidative Phosphorylation, Modulates AMP-dependent Kinase (AMPK)-Mammalian Target of Rapamycin (mTOR) Signaling, and Inhibits Proliferation of HepG2 Hepatocarcinoma Cells.

PubMed

Figarola, James L; Singhal, Jyotsana; Tompkins, Joshua D; Rogers, George W; Warden, Charles; Horne, David; Riggs, Arthur D; Awasthi, Sanjay; Singhal, Sharad S

2015-12-18

Mitochondrial oxidative phosphorylation produces most of the energy in aerobic cells by coupling respiration to the production of ATP. Mitochondrial uncouplers, which reduce the proton gradient across the mitochondrial inner membrane, create a futile cycle of nutrient oxidation without generating ATP. Regulation of mitochondrial dysfunction and associated cellular bioenergetics has been recently identified as a promising target for anticancer therapy. Here, we show that SR4 is a novel mitochondrial uncoupler that causes dose-dependent increase in mitochondrial respiration and dissipation of mitochondrial membrane potential in HepG2 hepatocarcinoma cells. These effects were reversed by the recoupling agent 6-ketocholestanol but not cyclosporin A and were nonexistent in mitochondrial DNA-depleted HepG2 cells. In isolated mouse liver mitochondria, SR4 similarly increased oxygen consumption independent of adenine nucleotide translocase and uncoupling proteins, decreased mitochondrial membrane potential, and promoted swelling of valinomycin-treated mitochondria in potassium acetate medium. Mitochondrial uncoupling in HepG2 cells by SR4 results in the reduction of cellular ATP production, increased ROS production, activation of the energy-sensing enzyme AMPK, and inhibition of acetyl-CoA carboxylase and mammalian target of rapamycin signaling pathways, leading to cell cycle arrest and apoptosis. Global analysis of SR4-associated differential gene expression confirms these observations, including significant induction of apoptotic genes and down-regulation of cell cycle, mitochondrial, and oxidative phosphorylation pathway transcripts at 24 h post-treatment. Collectively, our studies demonstrate that the previously reported indirect activation of AMPK and in vitro anticancer properties of SR4 as well as its beneficial effects in both animal xenograft and obese mice models could be a direct consequence of its mitochondrial uncoupling activity. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Influence of Reactive Transport on the Reduction of U(VI) in the Presence of Fe(III) and Nitrate: Implications for U(VI) Immobilization by Bioremediation / Biobarriers- Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

B.D. Wood

2007-01-01

Subsurface contamination by metals and radionuclides represent some of the most challenging remediation problems confronting the Department of Energy (DOE) complex. In situ remediation of these contaminants by dissimilatory metal reducing bacteria (DMRB) has been proposed as a potential cost effective remediation strategy. The primary focus of this research is to determine the mechanisms by which the fluxes of electron acceptors, electron donors, and other species can be controlled to maximize the transfer of reductive equivalents to the aqueous and solid phases. The proposed research is unique in the NABIR portfolio in that it focuses on (i) the role ofmore » flow and transport in the initiation of biostimulation and the successful sequestration of metals and radionuclides [specifically U(VI)], (ii) the subsequent reductive capacity and stability of the reduced sediments produced by the biostimulation process, and (iii) the potential for altering the growth of biomass in the subsurface by the addition of specific metabolic uncoupling compounds. A scientifically-based understanding of these phenomena are critical to the ability to design successful bioremediation schemes. The laboratory research will employ Shewanella putrefaciens (CN32), a facultative DMRB that can use Fe(III) oxides as a terminal electron acceptor. Sediment-packed columns will be inoculated with this organism, and the reduction of U(VI) by the DMRB will be stimulated by the addition of a carbon and energy source in the presence of Fe(III). Separate column experiments will be conducted to independently examine: (1) the importance of the abiotic reduction of U(VI) by biogenic Fe(II); (2) the influence of the transport process on Fe(III) reduction and U(VI) immobilization, with emphasis on methods for controlling the fluxes of aqueous species to maximize uranium reduction; (3) the reductive capacity of biologically-reduced sediments (with respect to re-oxidation by convective fluxes of O2 and NO3-) and the long-term stability of immobilized uranium mineral phases after bioremediation processes are complete, and (4) the ability for metabolic uncoupling compounds to maintain microbial growth while limiting biomass production. The results of the laboratory experiments will be used to develop mathematical descriptive models for the coupled transport and reduction processes.« less

Relationship between expression of muscle-specific uncoupling protein 2 messenger RNA and genetic selection toward growth in channel catfish

USDA-ARS?s Scientific Manuscript database

Uncoupling protein 2 is a member of the mitochondrial channel proteins that regulate the flow of hydrogen ions and ATP generation. The relationship between UCP2 and nutrient metabolism has been well-defined in humans but unclear in fish. We hypothesized that increased muscle growth in channel catf...

Mode detuning in systems of weakly coupled oscillators

NASA Astrophysics Data System (ADS)

Spencer, Ross L.; Robertson, Richard D.

2001-11-01

A system of weakly magnetically coupled oscillating blades is studied experimentally, computationally, and theoretically. It is found that when the uncoupled natural frequencies of the blades are nearly equal, the normal modes produced by the coupling are almost impossible to find experimentally if the random variation level in the system parameters is on the order of (or larger than) the relative differences between mode frequencies. But if the uncoupled natural frequencies are made to vary (detuned) in a smooth way such that the total relative spread in natural frequency exceeds the random variations, normal modes are rather easy to find. And if the detuned uncoupled frequencies of the system are parabolically distributed, the modes are found to be shaped like Hermite functions.

Compact Layers of Hybrid Halide Perovskites Fabricated via the Aerosol Deposition Process-Uncoupling Material Synthesis and Layer Formation.

PubMed

Panzer, Fabian; Hanft, Dominik; Gujar, Tanaji P; Kahle, Frank-Julian; Thelakkat, Mukundan; Köhler, Anna; Moos, Ralf

2016-04-08

We present the successful fabrication of CH₃NH₃PbI₃ perovskite layers by the aerosol deposition method (ADM). The layers show high structural purity and compactness, thus making them suitable for application in perovskite-based optoelectronic devices. By using the aerosol deposition method we are able to decouple material synthesis from layer processing. Our results therefore allow for enhanced and easy control over the fabrication of perovskite-based devices, further paving the way for their commercialization.

Modified relaxation dynamics and coherent energy exchange in coupled vibration-cavity polaritons

PubMed Central

Dunkelberger, A. D.; Spann, B. T.; Fears, K. P.; Simpkins, B. S.; Owrutsky, J. C.

2016-01-01

Coupling vibrational transitions to resonant optical modes creates vibrational polaritons shifted from the uncoupled molecular resonances and provides a convenient way to modify the energetics of molecular vibrations. This approach is a viable method to explore controlling chemical reactivity. In this work, we report pump–probe infrared spectroscopy of the cavity-coupled C–O stretching band of W(CO)6 and the direct measurement of the lifetime of a vibration-cavity polariton. The upper polariton relaxes 10 times more quickly than the uncoupled vibrational mode. Tuning the polariton energy changes the polariton transient spectra and relaxation times. We also observe quantum beats, so-called vacuum Rabi oscillations, between the upper and lower vibration-cavity polaritons. In addition to establishing that coupling to an optical cavity modifies the energy-transfer dynamics of the coupled molecules, this work points out the possibility of systematic and predictive modification of the excited-state kinetics of vibration-cavity polariton systems. PMID:27874010

Mediator binding to UASs is broadly uncoupled from transcription and cooperative with TFIID recruitment to promoters.

PubMed

Grünberg, Sebastian; Henikoff, Steven; Hahn, Steven; Zentner, Gabriel E

2016-11-15

Mediator is a conserved, essential transcriptional coactivator complex, but its in vivo functions have remained unclear due to conflicting data regarding its genome-wide binding pattern obtained by genome-wide ChIP Here, we used ChEC-seq, a method orthogonal to ChIP, to generate a high-resolution map of Mediator binding to the yeast genome. We find that Mediator associates with upstream activating sequences (UASs) rather than the core promoter or gene body under all conditions tested. Mediator occupancy is surprisingly correlated with transcription levels at only a small fraction of genes. Using the same approach to map TFIID, we find that TFIID is associated with both TFIID- and SAGA-dependent genes and that TFIID and Mediator occupancy is cooperative. Our results clarify Mediator recruitment and binding to the genome, showing that Mediator binding to UASs is widespread, partially uncoupled from transcription, and mediated in part by TFIID. © 2016 The Authors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bose, A; Gardel, EJ; Vidoudez, C

Oxidation-reduction reactions underlie energy generation in nearly all life forms. Although most organisms use soluble oxidants and reductants, some microbes can access solid-phase materials as electron-acceptors or -donors via extracellular electron transfer. Many studies have focused on the reduction of solid-phase oxidants. Far less is known about electron uptake via microbial extracellular electron transfer, and almost nothing is known about the associated mechanisms. Here we show that the iron-oxidizing photoautotroph Rhodopseudomonas palustris TIE-1 accepts electrons from a poised electrode, with carbon dioxide as the sole carbon source/electron acceptor. Both electron uptake and ruBisCo form I expression are stimulated by light.more » Electron uptake also occurs in the dark, uncoupled from photosynthesis. Notably, the pioABC operon, which encodes a protein system essential for photoautotrophic growth by ferrous iron oxidation, influences electron uptake. These data reveal a previously unknown metabolic versatility of photoferrotrophs to use extracellular electron transfer for electron uptake.« less

G2019S leucine-rich repeat kinase 2 causes uncoupling protein-mediated mitochondrial depolarization

PubMed Central

Papkovskaia, Tatiana D.; Chau, Kai-Yin; Inesta-Vaquera, Francisco; Papkovsky, Dmitri B.; Healy, Daniel G.; Nishio, Koji; Staddon, James; Duchen, Michael R.; Hardy, John; Schapira, Anthony H.V.; Cooper, J. Mark

2012-01-01

The G2019S leucine rich repeat kinase 2 (LRRK2) mutation is the most common genetic cause of Parkinson's disease (PD), clinically and pathologically indistinguishable from idiopathic PD. Mitochondrial abnormalities are a common feature in PD pathogenesis and we have investigated the impact of G2019S mutant LRRK2 expression on mitochondrial bioenergetics. LRRK2 protein expression was detected in fibroblasts and lymphoblasts at levels higher than those observed in the mouse brain. The presence of G2019S LRRK2 mutation did not influence LRRK2 expression in fibroblasts. However, the expression of the G2019S LRRK2 mutation in both fibroblast and neuroblastoma cells was associated with mitochondrial uncoupling. This was characterized by decreased mitochondrial membrane potential and increased oxygen utilization under basal and oligomycin-inhibited conditions. This resulted in a decrease in cellular ATP levels consistent with compromised cellular function. This uncoupling of mitochondrial oxidative phosphorylation was associated with a cell-specific increase in uncoupling protein (UCP) 2 and 4 expression. Restoration of mitochondrial membrane potential by the UCP inhibitor genipin confirmed the role of UCPs in this mechanism. The G2019S LRRK2-induced mitochondrial uncoupling and UCP4 mRNA up-regulation were LRRK2 kinase-dependent, whereas endogenous LRRK2 levels were required for constitutive UCP expression. We propose that normal mitochondrial function was deregulated by the expression of G2019S LRRK2 in a kinase-dependent mechanism that is a modification of the normal LRRK2 function, and this leads to the vulnerability of selected neuronal populations in PD. PMID:22736029

Mild uncoupling of respiration and phosphorylation as a mechanism providing nephro- and neuroprotective effects of penetrating cations of the SkQ family.

PubMed

Plotnikov, E Y; Silachev, D N; Jankauskas, S S; Rokitskaya, T I; Chupyrkina, A A; Pevzner, I B; Zorova, L D; Isaev, N K; Antonenko, Y N; Skulachev, V P; Zorov, D B

2012-09-01

It is generally accepted that mitochondrial production of reactive oxygen species is nonlinearly related to the value of the mitochondrial membrane potential with significant increment at values exceeding 150 mV. Due to this, high values of the membrane potential are highly dangerous, specifically under pathological conditions associated with oxidative stress. Mild uncoupling of oxidative phosphorylation is an approach to preventing hyperpolarization of the mitochondrial membrane. We confirmed data obtained earlier in our group that dodecylrhodamine 19 (C(12)R1) (a penetrating cation from SkQ family not possessing a plastoquinone group) has uncoupling properties, this fact making it highly potent for use in prevention of pathologies associated with oxidative stress induced by mitochondrial hyperpolarization. Further experiments showed that C(12)R1 provided nephroprotection under ischemia/reperfusion of the kidney as well as under rhabdomyolysis through diminishing of renal dysfunction manifested by elevated level of blood creatinine and urea. Similar nephroprotective properties were observed for low doses (275 nmol/kg) of the conventional uncoupler 2,4-dinitrophenol. Another penetrating cation that did not demonstrate protonophorous activity (SkQR4) had no effect on renal dysfunction. In experiments with induced ischemic stroke, C(12)R1 did not have any effect on the area of ischemic damage, but it significantly lowered neurological deficit. We conclude that beneficial effects of penetrating cation derivatives of rhodamine 19 in renal pathologies and brain ischemia may be at least partially explained by uncoupling of oxidation and phosphorylation.

Availability of the key metabolic substrates dictates the respiratory response of cancer cells to the mitochondrial uncoupling.

PubMed

Zhdanov, Alexander V; Waters, Alicia H C; Golubeva, Anna V; Dmitriev, Ruslan I; Papkovsky, Dmitri B

2014-01-01

Active glycolysis and glutaminolysis provide bioenergetic stability of cancer cells in physiological conditions. Under hypoxia, metabolic and mitochondrial disorders, or pharmacological treatment, a deficit of key metabolic substrates may become life-threatening to cancer cells. We analysed the effects of mitochondrial uncoupling by FCCP on the respiration of cells fed by different combinations of Glc, Gal, Gln and Pyr. In cancer PC12 and HCT116 cells, a large increase in O2 consumption rate (OCR) upon uncoupling was only seen when Gln was combined with either Glc or Pyr. Inhibition of glutaminolysis with BPTES abolished this effect. Despite the key role of Gln, addition of FCCP inhibited respiration and induced apoptosis in cells supplied with Gln alone or Gal/Gln. For all substrate combinations, amplitude of respiratory responses to FCCP did not correlate with Akt, Erk and AMPK phosphorylation, cellular ATP, and resting OCR, mitochondrial Ca(2+) or membrane potential. However, we propose that proton motive force could modulate respiratory response to FCCP by regulating mitochondrial transport of Gln and Pyr, which decreases upon mitochondrial depolarisation. As a result, an increase in respiration upon uncoupling is abolished in cells, deprived of Gln or Pyr (Glc). Unlike PC12 or HCT116 cells, mouse embryonic fibroblasts were capable of generating pronounced response to FCCP when deprived of Gln, thus exhibiting lower dependence on glutaminolysis. Overall, the differential regulation of the respiratory response to FCCP by metabolic environment suggests that mitochondrial uncoupling has a potential for substrate-specific inhibition of cell function, and can be explored for selective cancer treatment. © 2013.

The development of structure-activity relationships for mitochondrial dysfunction: uncoupling of oxidative phosphorylation.

PubMed

Naven, Russell T; Swiss, Rachel; Klug-McLeod, Jacquelyn; Will, Yvonne; Greene, Nigel

2013-01-01

Mitochondrial dysfunction has been implicated as an important factor in the development of idiosyncratic organ toxicity. An ability to predict mitochondrial dysfunction early in the drug development process enables the deselection of those drug candidates with potential safety liabilities, allowing resources to be focused on those compounds with the highest chance of success to the market. A database of greater than 2000 compounds was analyzed to identify structural and physicochemical features associated with the uncoupling of oxidative phosphorylation (herein defined as an increase in basal respiration). Many toxicophores associated with potent uncoupling activity were identified, and these could be divided into two main mechanistic classes, protonophores and redox cyclers. For the protonophores, potent uncoupling activity was often promoted by high lipophilicity and apparent stabilization of the anionic charge resulting from deprotonation of the protonophore. The potency of redox cyclers did not appear to be prone to variations in lipophilicity. Only 11 toxicophores were of sufficient predictive performance that they could be incorporated into a structural-alert model. Each alert was associated with one of three confidence levels (high, medium, and low) depending upon the lipophilicity-activity profile of the structural class. The final model identified over 68% of those compounds with potent uncoupling activity and with a value for specificity above 99%. We discuss the advantages and limitations of this approach and conclude that although structural alert methodology is useful for identifying toxicophores associated with mitochondrial dysfunction, they are not a replacement for the mitochondrial dysfunction assays in early screening paradigms.

Intrinsic uncoupling of mitochondrial proton pumps. 2. Modeling studies.

PubMed

Pietrobon, D; Zoratti, M; Azzone, G F; Caplan, S R

1986-02-25

The thermodynamic and kinetic properties associated with intrinsic uncoupling in a six-state model of a redox proton pump have been studied by computing the flow-force relations for different degrees of coupling. Analysis of these relations shows the regulatory influence of the thermodynamic forces on the extent and relative contributions of redox slip and proton slip. Inhibition has been introduced into the model in two different ways, corresponding to possible modes of action of experimental inhibitors. Experiments relating the rate of electron transfer to delta microH at static head upon progressive inhibition of the pumps have been simulated considering (1) the limiting case that the nonzero rate of electron transfer at static head is only due to intrinsic uncoupling (no leaks) and (2) the experimentally observed case that about 30% of the nonzero rate of electron transfer at static head is due to a constant proton leakage conductance in parallel with the pumps, the rest being due to intrinsic uncoupling. The same simulations have been performed for experiments in which the rate of electron transfer is varied by varying the substrate concentration rather than by using an inhibitor. The corresponding experimental results obtained by measuring delta microH and the rate of electron transfer at different succinate concentrations in rat liver mitochondria are presented. Comparison between simulated behavior and experimental results leads to the general conclusion that the typical relationship between rate of electron transfer and delta microH found in mitochondria at static head could certainly be a manifestation of some degree of intrinsic uncoupling in the redox proton pumps.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitochondrial Proton Leak Plays a Critical Role in Pathogenesis of Cardiovascular Diseases.

PubMed

Cheng, Jiali; Nanayakkara, Gayani; Shao, Ying; Cueto, Ramon; Wang, Luqiao; Yang, William Y; Tian, Ye; Wang, Hong; Yang, Xiaofeng

2017-01-01

Mitochondrial proton leak is the principal mechanism that incompletely couples substrate oxygen to ATP generation. This chapter briefly addresses the recent progress made in understanding the role of proton leak in the pathogenesis of cardiovascular diseases. Majority of the proton conductance is mediated by uncoupling proteins (UCPs) located in the mitochondrial inner membrane. It is evident that the proton leak and reactive oxygen species (ROS) generated from electron transport chain (ETC) in mitochondria are linked to each other. Increased ROS production has been shown to induce proton conductance, and in return, increased proton conductance suppresses ROS production, suggesting the existence of a positive feedback loop that protects the biological systems from detrimental effects of augmented oxidative stress. There is mounting evidence attributing to proton leak and uncoupling proteins a crucial role in the pathogenesis of cardiovascular disease. We can surmise the role of "uncoupling" in cardiovascular disorders as follows; First, the magnitude of the proton leak and the mechanism involved in mediating the proton leak determine whether there is a protective effect against ischemia-reperfusion (IR) injury. Second, uncoupling by UCP2 preserves vascular function in diet-induced obese mice as well as in diabetes. Third, etiology determines whether the proton conductance is altered or not during hypertension. And fourth, proton leak regulates ATP synthesis-uncoupled mitochondrial ROS generation, which determines pathological activation of endothelial cells for recruitment of inflammatory cells. Continue effort in improving our understanding in the role of proton leak in the pathogenesis of cardiovascular and metabolic diseases would lead to identification of novel therapeutic targets for treatment.

The plant energy-dissipating mitochondrial systems: depicting the genomic structure and the expression profiles of the gene families of uncoupling protein and alternative oxidase in monocots and dicots.

PubMed

Borecky, Jirí; Nogueira, Fábio T S; de Oliveira, Kívia A P; Maia, Ivan G; Vercesi, Aníbal E; Arruda, Paulo

2006-01-01

The simultaneous existence of alternative oxidases and uncoupling proteins in plants has raised the question as to why plants need two energy-dissipating systems with apparently similar physiological functions. A probably complete plant uncoupling protein gene family is described and the expression profiles of this family compared with the multigene family of alternative oxidases in Arabidopsis thaliana and sugarcane (Saccharum sp.) employed as dicot and monocot models, respectively. In total, six uncoupling protein genes, AtPUMP1-6, were recognized within the Arabidopsis genome and five (SsPUMP1-5) in a sugarcane EST database. The recombinant AtPUMP5 protein displayed similar biochemical properties as AtPUMP1. Sugarcane possessed four Arabidopsis AOx1-type orthologues (SsAOx1a-1d); no sugarcane orthologue corresponding to Arabidopsis AOx2-type genes was identified. Phylogenetic and expression analyses suggested that AtAOx1d does not belong to the AOx1-type family but forms a new (AOx3-type) family. Tissue-enriched expression profiling revealed that uncoupling protein genes were expressed more ubiquitously than the alternative oxidase genes. Distinct expression patterns among gene family members were observed between monocots and dicots and during chilling stress. These findings suggest that the members of each energy-dissipating system are subject to different cell or tissue/organ transcriptional regulation. As a result, plants may respond more flexibly to adverse biotic and abiotic conditions, in which oxidative stress is involved.

Percolation in real interdependent networks

NASA Astrophysics Data System (ADS)

Radicchi, Filippo

2015-07-01

The function of a real network depends not only on the reliability of its own components, but is affected also by the simultaneous operation of other real networks coupled with it. Whereas theoretical methods of direct applicability to real isolated networks exist, the frameworks developed so far in percolation theory for interdependent network layers are of little help in practical contexts, as they are suited only for special models in the limit of infinite size. Here, we introduce a set of heuristic equations that takes as inputs the adjacency matrices of the layers to draw the entire phase diagram for the interconnected network. We demonstrate that percolation transitions in interdependent networks can be understood by decomposing these systems into uncoupled graphs: the intersection among the layers, and the remainders of the layers. When the intersection dominates the remainders, an interconnected network undergoes a smooth percolation transition. Conversely, if the intersection is dominated by the contribution of the remainders, the transition becomes abrupt even in small networks. We provide examples of real systems that have developed interdependent networks sharing cores of `high quality’ edges to prevent catastrophic failures.

Whole genome siRNA cell-based screen links mitochondria to Akt signaling network through uncoupling of electron transport chain

PubMed Central

Senapedis, William T.; Kennedy, Caleb J.; Boyle, Patrick M.; Silver, Pamela A.

2011-01-01

Forkhead transcription factors (FOXOs) alter a diverse array of cellular processes including the cell cycle, oxidative stress resistance, and aging. Insulin/Akt activation directs phosphorylation and cytoplasmic sequestration of FOXO away from its target genes and serves as an endpoint of a complex signaling network. Using a human genome small interfering RNA (siRNA) library in a cell-based assay, we identified an extensive network of proteins involved in nuclear export, focal adhesion, and mitochondrial respiration not previously implicated in FOXO localization. Furthermore, a detailed examination of mitochondrial factors revealed that loss of uncoupling protein 5 (UCP5) modifies the energy balance and increases free radicals through up-regulation of uncoupling protein 3 (UCP3). The increased superoxide content induces c-Jun N-terminal kinase 1 (JNK1) kinase activity, which in turn affects FOXO localization through a compensatory dephosphorylation of Akt. The resulting nuclear FOXO increases expression of target genes, including mitochondrial superoxide dismutase. By connecting free radical defense and mitochondrial uncoupling to Akt/FOXO signaling, these results have implications in obesity and type 2 diabetes development and the potential for therapeutic intervention. PMID:21460183

Whole genome siRNA cell-based screen links mitochondria to Akt signaling network through uncoupling of electron transport chain.

PubMed

Senapedis, William T; Kennedy, Caleb J; Boyle, Patrick M; Silver, Pamela A

2011-05-15

Forkhead transcription factors (FOXOs) alter a diverse array of cellular processes including the cell cycle, oxidative stress resistance, and aging. Insulin/Akt activation directs phosphorylation and cytoplasmic sequestration of FOXO away from its target genes and serves as an endpoint of a complex signaling network. Using a human genome small interfering RNA (siRNA) library in a cell-based assay, we identified an extensive network of proteins involved in nuclear export, focal adhesion, and mitochondrial respiration not previously implicated in FOXO localization. Furthermore, a detailed examination of mitochondrial factors revealed that loss of uncoupling protein 5 (UCP5) modifies the energy balance and increases free radicals through up-regulation of uncoupling protein 3 (UCP3). The increased superoxide content induces c-Jun N-terminal kinase 1 (JNK1) kinase activity, which in turn affects FOXO localization through a compensatory dephosphorylation of Akt. The resulting nuclear FOXO increases expression of target genes, including mitochondrial superoxide dismutase. By connecting free radical defense and mitochondrial uncoupling to Akt/FOXO signaling, these results have implications in obesity and type 2 diabetes development and the potential for therapeutic intervention.

Kidney transplantation restored uncoupled bone turnover in end-stage renal disease.

PubMed

Kawarazaki, Hiroo; Shibagaki, Yugo; Kido, Ryo; Nakajima, Ichiro; Fuchinoue, Shohei; Ando, Katsuyuki; Fujita, Toshiro; Fukagawa, Masafumi; Teraoka, Satoshi; Fukumoto, Seiji

2012-07-01

While kidney transplantation (KTx) reverses many disorders associated with end-stage renal disease (ESRD), patients who have received KTx often have chronic kidney disease and bone and mineral disorder (CKD-MBD). However, it is unknown how bone metabolism changes by KTx. Living donor-KTx recipients (n = 34) at Tokyo Women's Medical University were prospectively recruited and the levels of bone-specific alkaline phosphatase (BAP) and serum cross-linked N-telopeptides of Type 1 collagen (NTX) were measured before, 6 and 12 months after transplantation. Before KTx, serum BAP was within the reference range in more than half of patients while NTX was high in most patients. Serum NTX was higher in patients with longer dialysis durations compared to that with shorter durations before KTx. However, there was no difference in serum BAP between these patients. After KTx, BAP increased while NTX decreased along with the decline of PTH. In addition, the numbers of patients who showed high BAP and NTX were comparable after KTx. These results suggest that bone formation is suppressed and uncoupled with bone resorption in patients with ESRD and this uncoupling is restored by KTx. Further studies are necessary to clarify the mechanism of bone uncoupling in patients with ESRD.

Nitric oxide, PKC-ε, and connexin43 are crucial for ischemic preconditioning-induced chemical gap junction uncoupling

PubMed Central

Sun, Tao; Hao, Li; Lin, Ming-Jie; Zhong, Jing-Quan

2016-01-01

Ischemic preconditioning (IPC) maintains connexin43 (Cx43) phosphorylation and reduces chemical gap junction (GJ) coupling in cardiomyocytes to protect against ischemic damage. However, the signal transduction pathways underlying these effects are not fully understood. Here, we investigated whether nitric oxide (NO) and protein kinase C-ε (PKC-ε) contribute to IPC-induced cardioprotection by maintaining Cx43 phosphorylation and inhibiting chemical GJ coupling. IPC reduced ischemia-induced myocardial infarction and increased cardiomyocyte survival; phosphorylated Cx43, eNOS, and PKC-ε levels; and chemical GJ uncoupling. Administration of the NO donor SNAP mimicked the effects of IPC both in vivo and in vitro, maintaining Cx43 phosphorylation, promoting chemical GJ uncoupling, and reducing myocardial infarction. Preincubation with the NO synthase inhibitor L-NAME or PKC-ε translocation inhibitory peptide (PKC-ε-TIP) abolished these effects of IPC. Additionally, by inducing NO production, IPC induced translocation of PKC-ε, but not PKC-δ, from the cytosolic to the membrane fraction in primary cardiac myocytes. IPC-induced cardioprotection thus involves increased NO production, PKC-ε translocation, Cx43 phosphorylation, and chemical GJ uncoupling. PMID:27655723

Uncoupling RARA transcriptional activation and degradation clarifies the bases for APL response to therapies

PubMed Central

Ablain, Julien; Leiva, Magdalena; Peres, Laurent; Fonsart, Julien; Anthony, Elodie

2013-01-01

In PML/RARA-driven acute promyelocytic leukemia (APL), retinoic acid (RA) induces leukemia cell differentiation and transiently clears the disease. Molecularly, RA activates PML/RARA-dependent transcription and also initiates its proteasome-mediated degradation. In contrast, arsenic, the other potent anti-APL therapy, only induces PML/RARA degradation by specifically targeting its PML moiety. The respective contributions of RA-triggered transcriptional activation and proteolysis to clinical response remain disputed. Here, we identify synthetic retinoids that potently activate RARA- or PML/RARA-dependent transcription, but fail to down-regulate RARA or PML/RARA protein levels. Similar to RA, these uncoupled retinoids elicit terminal differentiation, but unexpectedly fail to impair leukemia-initiating activity of PML/RARA-transformed cells ex vivo or in vivo. Accordingly, the survival benefit conferred by uncoupled retinoids in APL mice is dramatically lower than the one provided by RA. Differentiated APL blasts sorted from uncoupled retinoid–treated mice retain PML/RARA expression and reinitiate APL in secondary transplants. Thus, differentiation is insufficient for APL eradication, whereas PML/RARA loss is essential. These observations unify the modes of action of RA and arsenic and shed light on the potency of their combination in mice or patients. PMID:23509325

Uncoupling RARA transcriptional activation and degradation clarifies the bases for APL response to therapies.

PubMed

Ablain, Julien; Leiva, Magdalena; Peres, Laurent; Fonsart, Julien; Anthony, Elodie; de Thé, Hugues

2013-04-08

In PML/RARA-driven acute promyelocytic leukemia (APL), retinoic acid (RA) induces leukemia cell differentiation and transiently clears the disease. Molecularly, RA activates PML/RARA-dependent transcription and also initiates its proteasome-mediated degradation. In contrast, arsenic, the other potent anti-APL therapy, only induces PML/RARA degradation by specifically targeting its PML moiety. The respective contributions of RA-triggered transcriptional activation and proteolysis to clinical response remain disputed. Here, we identify synthetic retinoids that potently activate RARA- or PML/RARA-dependent transcription, but fail to down-regulate RARA or PML/RARA protein levels. Similar to RA, these uncoupled retinoids elicit terminal differentiation, but unexpectedly fail to impair leukemia-initiating activity of PML/RARA-transformed cells ex vivo or in vivo. Accordingly, the survival benefit conferred by uncoupled retinoids in APL mice is dramatically lower than the one provided by RA. Differentiated APL blasts sorted from uncoupled retinoid-treated mice retain PML/RARA expression and reinitiate APL in secondary transplants. Thus, differentiation is insufficient for APL eradication, whereas PML/RARA loss is essential. These observations unify the modes of action of RA and arsenic and shed light on the potency of their combination in mice or patients.

Influence of antimycin A and uncouplers on anaerobic photosynthesis in isolated chloroplasts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slovacek, R.E.; Hind, G.

1977-10-01

Anaerobiosis depresses the light- and bicarbonate-saturated rates of O/sub 2/ evolution in intact spinach (Spinacia oleracea) chloroplasts by as much as 3-fold from those observed under aerobic conditions. These lower rates are accelerated 2-fold or more by the addition of 1 ..mu..m antimycin A or by low concentrations of the uncouplers 0.3 mM NH/sub 4/Cl or 0.25 ..mu..m carbonyl cyanide m-chlorophenylhydrazone. Oxaloacetate and glycerate 3-phosphate reduction rates are also increased by antimycin A or an uncoupler under anaerobic conditions. At intermediate light intensities, the rate accelerations by either antimycin A or uncoupler are inversely proportional to the adenosine 5'-triphosphate demandmore » of the reduction process for the acceptors HCO/sub 3//sup -/, glycerate 3-phosphate, and oxaloacetate. The acceleration of bicarbonate-supported O/sub 2/ evolution may also be produced by adding an adenosine 5'-triphosphate sink (ribose 5-phosphate) to anaerobic chloroplasts. The above results suggest that a proton gradient back pressure resulting from antimycin A-sensitive cyclic electron flow is responsible for the depression of light-saturated photosynthesis under anaerobiosis.« less

Relation of Mitochondrial Oxygen Consumption in Peripheral Blood Mononuclear Cells to Vascular Function in Type 2 Diabetes Mellitus

PubMed Central

Hartman, Mor-Li; Shirihai, Orian S.; Holbrook, Monika; Xu, Guoquan; Kocherla, Marsha; Shah, Akash; Fetterman, Jessica L.; Kluge, Matthew A.; Frame, Alissa A.; Hamburg, Naomi M.; Vita, Joseph A.

2014-01-01

Recent studies have shown mitochondrial dysfunction and increased production of reactive oxygen species in peripheral blood mononuclear cells (PBMC’s) and endothelial cells from patients with diabetes mellitus. Mitochondria oxygen consumption is coupled to ATP production and also occurs in an uncoupled fashion during formation of reactive oxygen species by components of the electron transport chain and other enzymatic sites. We therefore hypothesized that diabetes would be associated with higher total and uncoupled oxygen consumption in PBMC’s that would correlate with endothelial dysfunction. We developed a method to measure oxygen consumption in freshly isolated PBMC’s and applied it to 26 patients with type 2 diabetes mellitus and 28 non-diabetic controls. Basal (192±47 vs. 161±44 pMoles/min, P=0.01), uncoupled (64±16 vs. 53±16 pMoles/min, P=0.007), and maximal (795±87 vs. 715±128 pMoles/min, P=0.01) oxygen consumption rates were higher in diabetic patients compared to controls. There were no significant correlations between oxygen consumption rates and endothelium-dependent flow-mediated dilation measured by vascular ultrasound. Non-endothelium-dependent nitroglycerin-mediated dilation was lower in diabetics (10.1±6.6 vs. 15.8±4.8%, P=0.03) and correlated with maximal oxygen consumption (R= −0.64, P=0.001). In summary, we found that diabetes mellitus is associated with a pattern of mitochondrial oxygen consumption consistent with higher production of reactive oxygen species. The correlation between oxygen consumption and nitroglycerin-mediated dilation may suggest a link between mitochondrial dysfunction and vascular smooth muscle cell dysfunction that merits further study. Finally, the described method may have utility for assessment of mitochondrial function in larger scale observational and interventional studies in humans. PMID:24558030

Treating Co-occurring Depression and Anxiety: Modeling the Dynamics of Psychopathology and Psychotherapy Using the Time Varying Effect Model

PubMed Central

Wright, Aidan G.C.; Hallquist, Michael N.; Swartz, Holly A.; Frank, Ellen; Cyranowski, Jill M.

2014-01-01

Objective We demonstrate the utility of the time-varying effect model (TVEM) for the analysis of psychotherapy data, with the aim of elucidating complex patterns of change over time and dynamic associations between constructs of interest. Specifically, we examine the association between depression and co-occurring anxiety in a sample of adults treated with interpersonal psychotherapy for depression (IPT) or a variant designed to address both depression and co-occurring anxiety (IPT-PS, IPT for depression with panic and anxiety symptoms). Method Seventy-eight (82% female) adult outpatients with major depression and co-occurring anxiety were assessed at each of 16 outpatient treatment sessions using the Hamilton rating scales for depression and anxiety. Results On average, depressive symptoms declined in a quadratic form over the course of treatment. While the association between anxiety and depression was modest early in treatment, it strengthened over the middle and latter treatment phases. Finally, exploratory analyses suggest that while IPT and IPT-PS were similarly effective in reducing depressive symptoms, IPT-PS may be more effective at uncoupling the association between core anxiety and depressive symptoms. Conclusions Findings point to the utility of the TVEM for psychotherapy research, and the importance of assessing anxiety in the course of treating depression, especially following the initial phase of treatment (i.e., after session 5). PMID:24041230

Analysis of Rhizome Development in Oryza longistaminata, a Wild Rice Species.

PubMed

Yoshida, Akiko; Terada, Yasuhiko; Toriba, Taiyo; Kose, Katsumi; Ashikari, Motoyuki; Kyozuka, Junko

2016-10-01

Vegetative reproduction is a form of asexual propagation in plants. A wide range of plants develop rhizomes, modified stems that grow underground horizontally, as a means of vegetative reproduction. In rhizomatous species, despite their distinct developmental patterns, both rhizomes and aerial shoots derive from axillary buds. Therefore, it is of interest to understand the basis of rhizome initiation and development. Oryza longistaminata, a wild rice species, develops rhizomes. We analyzed bud initiation and growth of O. longistaminata rhizomes using various methods of morphological observation. We show that, unlike aerial shoot buds that contain a few leaves only, rhizome buds initiate several leaves and bend to grow at right angles to the original rhizome. Rhizomes are maintained in the juvenile phase irrespective of the developmental phase of the aerial shoot. Stem elongation and reproductive transition are tightly linked in the aerial shoots, but are uncoupled in the rhizome. Our findings indicate that developmental programs operate independently in the rhizomes and aerial shoots. Temporal modification of the developmental pathways that are common to rhizomes and aerial shoots may be the source of developmental plasticity. Furthermore, the creation of new developmental systems appears to be necessary for rhizome development. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Finite element solution of nonlinear eddy current problems with periodic excitation and its industrial applications☆

PubMed Central

Bíró, Oszkár; Koczka, Gergely; Preis, Kurt

2014-01-01

An efficient finite element method to take account of the nonlinearity of the magnetic materials when analyzing three-dimensional eddy current problems is presented in this paper. The problem is formulated in terms of vector and scalar potentials approximated by edge and node based finite element basis functions. The application of Galerkin techniques leads to a large, nonlinear system of ordinary differential equations in the time domain. The excitations are assumed to be time-periodic and the steady-state periodic solution is of interest only. This is represented either in the frequency domain as a finite Fourier series or in the time domain as a set of discrete time values within one period for each finite element degree of freedom. The former approach is the (continuous) harmonic balance method and, in the latter one, discrete Fourier transformation will be shown to lead to a discrete harmonic balance method. Due to the nonlinearity, all harmonics, both continuous and discrete, are coupled to each other. The harmonics would be decoupled if the problem were linear, therefore, a special nonlinear iteration technique, the fixed-point method is used to linearize the equations by selecting a time-independent permeability distribution, the so-called fixed-point permeability in each nonlinear iteration step. This leads to uncoupled harmonics within these steps. As industrial applications, analyses of large power transformers are presented. The first example is the computation of the electromagnetic field of a single-phase transformer in the time domain with the results compared to those obtained by traditional time-stepping techniques. In the second application, an advanced model of the same transformer is analyzed in the frequency domain by the harmonic balance method with the effect of the presence of higher harmonics on the losses investigated. Finally a third example tackles the case of direct current (DC) bias in the coils of a single-phase transformer. PMID:24829517

Finite element solution of nonlinear eddy current problems with periodic excitation and its industrial applications.

PubMed

Bíró, Oszkár; Koczka, Gergely; Preis, Kurt

2014-05-01

An efficient finite element method to take account of the nonlinearity of the magnetic materials when analyzing three-dimensional eddy current problems is presented in this paper. The problem is formulated in terms of vector and scalar potentials approximated by edge and node based finite element basis functions. The application of Galerkin techniques leads to a large, nonlinear system of ordinary differential equations in the time domain. The excitations are assumed to be time-periodic and the steady-state periodic solution is of interest only. This is represented either in the frequency domain as a finite Fourier series or in the time domain as a set of discrete time values within one period for each finite element degree of freedom. The former approach is the (continuous) harmonic balance method and, in the latter one, discrete Fourier transformation will be shown to lead to a discrete harmonic balance method. Due to the nonlinearity, all harmonics, both continuous and discrete, are coupled to each other. The harmonics would be decoupled if the problem were linear, therefore, a special nonlinear iteration technique, the fixed-point method is used to linearize the equations by selecting a time-independent permeability distribution, the so-called fixed-point permeability in each nonlinear iteration step. This leads to uncoupled harmonics within these steps. As industrial applications, analyses of large power transformers are presented. The first example is the computation of the electromagnetic field of a single-phase transformer in the time domain with the results compared to those obtained by traditional time-stepping techniques. In the second application, an advanced model of the same transformer is analyzed in the frequency domain by the harmonic balance method with the effect of the presence of higher harmonics on the losses investigated. Finally a third example tackles the case of direct current (DC) bias in the coils of a single-phase transformer.

Structure-activity relationships for chloro- and nitrophenol toxicity in the pollen tube growth test

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schueuermann, G.; Somashekar, R.K.; Kristen, U.

Acute toxicity of 10 chlorophenols and 10 nitrophenols with identical substitution patterns is analyzed with the pollen tube growth (PTG) test. Concentration values of 50% growth inhibition (IC50) between 0.1 and 300 mg/L indicate that the absolute sensitivity of this alternative biotest is comparable to conventional aquatic test systems. Analysis of quantitative structure-activity relationships using lipophilicity (log K{sub ow}), acidity (pK{sub a}), and quantum chemical parameters to model intrinsic acidity, solvation interactions, and nucleophilicity reveals substantial differences between the intraseries trends of log IC50. With chlorophenols, a narcotic-type relationship is derived, which, however, shows marked differences in slope and interceptmore » when compared to reference regression equations for polar narcosis. Regression analysis of nitrophenol toxicity suggests interpretation in terms of two modes of action: oxidative uncoupling activity is associated with a pK{sub a} window from 3.8 to 8.5, and more acidic congeners with diortho-substitution show a transition from uncoupling to a narcotic mode of action with decreasing pK{sub a} and log K{sub ow}. Model calculations for phenol nucleophilicity suggest that differences in the phenol readiness for glucuronic acid conjugation as a major phase-II detoxication pathway have no direct influence on acute PTG toxicity of the compounds.« less

Alterations in proton leak, oxidative status and uncoupling protein 3 content in skeletal muscle subsarcolemmal and intermyofibrillar mitochondria in old rats

PubMed Central

2014-01-01

Background We considered of interest to evaluate how aging affects mitochondrial function in skeletal muscle. Methods We measured mitochondrial oxidative capacity and proton leak, together with lipid oxidative damage, superoxide dismutase specific activity and uncoupling protein 3 content, in subsarcolemmal and intermyofibrillar mitochondria from adult (six months) and old (two years) rats. Body composition, resting metabolic rate and plasma non esterified fatty acid levels were also assessed. Results Old rats displayed significantly higher body energy and lipids, while body proteins were significantly lower, compared to adult rats. In addition, plasma non esterified fatty acid levels were significantly higher, while resting metabolic rates were found to be significantly lower, in old rats compared to adult ones. Significantly lower oxidative capacities in whole tissue homogenates and in intermyofibrillar and subsarcolemmal mitochondria were found in old rats compared to adult ones. Subsarcolemmal and intermyofibrillar mitochondria from old rats exhibited a significantly lower proton leak rate, while oxidative damage was found to be significantly higher only in subsarcolemmal mitochondria. Mitochondrial superoxide dismutase specific activity was not significantly affected in old rats, while significantly higher content of uncoupling protein 3 was found in both mitochondrial populations from old rats compared to adult ones, although the magnitude of the increase was lower in subsarcolemmal than in intermyofibrillar mitochondria. Conclusions The decrease in oxidative capacity and proton leak in intermyofibrillar and subsarcolemmal mitochondria could induce a decline in energy expenditure and thus contribute to the reduced resting metabolic rate found in old rats, while oxidative damage is present only in subsarcolemmal mitochondria. PMID:24950599

Arterial Ventricular Uncoupling with Age and Disease and Recoupling with Exercise

PubMed Central

Chantler, Paul D

2017-01-01

The deterioration in arterial and cardiac function with aging impairs arterial ventricular coupling, an important determinant of cardiovascular performance. However, exercise training improves arterial ventricular coupling especially during exercise during the age and disease process. This review examines the concept of arterial-ventricular coupling, and how age, and disease uncouples but exercise training recouples the heart and arterial system. PMID:28072585

A Crank–Nicolson Leapfrog stabilization: Unconditional stability and two applications

DOE PAGES

Jiang, Nan; Kubacki, Michaela; Layton, William; ...

2014-12-09

We propose and analyze a linear stabilization of the Crank-Nicolson Leapfrog (CNLF) method that removes all time step/CFL conditions for stability and controls the unstable mode. It also increases the SPD part of the linear system to be solved at each time step while increasing solution accuracy. We give a proof of unconditional stability of the method as well as a proof of unconditional, asymptotic stability of both the stable and unstable modes. As a result, we illustrate two applications of the method: uncoupling groundwater-surface water flows and Stokes flow plus a Coriolis term.

Uncoupling of oxidative phosphorylation and Smac/DIABLO release are not sufficient to account for induction of apoptosis by sulindac sulfide in human colorectal cancer cells.

PubMed

Daouphars, Mikael; Koufany, Meriem; Benani, Alexandre; Marchal, Sophie; Merlin, Jean-Louis; Netter, Patrick; Jouzeau, Jean-Yves

2005-04-01

Non-steroidal anti-inflammatory drugs (NSAIDs) have shown chemopreventive properties in colorectal cancer, involving both cyclooxygenase (COX)-dependent and -independent mechanisms. Apart from their selectivity for COX isoenzymes, NSAIDs differ in their acidic character which supports ability to uncouple oxidative phosphorylation. To assess the possible contribution of uncoupling to their antineoplastic properties, we compared the effect of sulindac sulfide (SS), an acidic NSAID and NS-398, a non-acidic tricyclic, on mitochondrial function and apoptosis in colorectal cancer cell lines (HT29, Caco-2, HCT15 and HCT116). Although cell lines displayed a different COX status, SS and NS-398 caused growth arrest in a dose-related manner. High dose (10(-4)M) of SS but not of NS-398, increased the percentage of subG1 cell population while reducing mitochondrial transmembrane potential (DeltaPsim). Cyclosporin A (CsA, 1 microM) prevented collapse of DeltaPsim induced by 10(-4)M SS but not by 7.5 microM FCCP used as a protonophoric control. SS and FCCP increased the cytosolic release of Smac/DIABLO which was differently affected by CsA pretreatment depending on the uncoupler. Finally, 7.5 microM FCCP failed to induce apoptosis whereas CsA prevented apoptosis induced by SS from 16% in HCT15 to 41% in HCT116. The present study shows that despite the ability of sulindac sulfide to behave as a protonophoric uncoupler, CsA-sensitive opening of mitochondrial permeability transition pore contributes little to its pro-apoptotic effect in colorectal cancer cells.

Derivatives of Rhodamine 19 as Mild Mitochondria-targeted Cationic Uncouplers*

PubMed Central

Antonenko, Yuri N.; Avetisyan, Armine V.; Cherepanov, Dmitry A.; Knorre, Dmitry A.; Korshunova, Galina A.; Markova, Olga V.; Ojovan, Silvia M.; Perevoshchikova, Irina V.; Pustovidko, Antonina V.; Rokitskaya, Tatyana I.; Severina, Inna I.; Simonyan, Ruben A.; Smirnova, Ekaterina A.; Sobko, Alexander A.; Sumbatyan, Natalia V.; Severin, Fedor F.; Skulachev, Vladimir P.

2011-01-01

A limited decrease in mitochondrial membrane potential can be beneficial for cells, especially under some pathological conditions, suggesting that mild uncouplers (protonophores) causing such an effect are promising candidates for therapeutic uses. The great majority of protonophores are weak acids capable of permeating across membranes in their neutral and anionic forms. In the present study, protonophorous activity of a series of derivatives of cationic rhodamine 19, including dodecylrhodamine (C12R1) and its conjugate with plastoquinone (SkQR1), was revealed using a variety of assays. Derivatives of rhodamine B, lacking dissociable protons, showed no protonophorous properties. In planar bilayer lipid membranes, separating two compartments differing in pH, diffusion potential of H+ ions was generated in the presence of C12R1 and SkQR1. These compounds induced pH equilibration in liposomes loaded with the pH probe pyranine. C12R1 and SkQR1 partially stimulated respiration of rat liver mitochondria in State 4 and decreased their membrane potential. Also, C12R1 partially stimulated respiration of yeast cells but, unlike the anionic protonophore FCCP, did not suppress their growth. Loss of function of mitochondrial DNA in yeast (grande-petite transformation) is known to cause a major decrease in the mitochondrial membrane potential. We found that petite yeast cells are relatively more sensitive to the anionic uncouplers than to C12R1 compared with grande cells. Together, our data suggest that rhodamine 19-based cationic protonophores are self-limiting; their uncoupling activity is maximal at high membrane potential, but the activity decreases membrane potentials, which causes partial efflux of the uncouplers from mitochondria and, hence, prevents further membrane potential decrease. PMID:21454507

On the causes and consequences of the uncoupler-like effects of quercetin and dehydrosilybin in H9c2 cells

PubMed Central

Mouithys-Mickalad, Ange; Dostal, Zdenek; Serteyn, Didier; Modriansky, Martin

2017-01-01

Quercetin and dehydrosilybin are polyphenols which are known to behave like uncouplers of respiration in isolated mitochondria. Here we investigated whether the effect is conserved in whole cells. Following short term incubation, neither compound uncouples mitochondrial respiration in whole H9c2 cells below 50μM. However, following hypoxia, or long term incubation, leak (state IV with oligomycin) oxygen consumption is increased by quercetin. Both compounds partially protected complex I respiration, but not complex II in H9c2 cells following hypoxia. In a permeabilised H9c2 cell model, the increase in leak respiration caused by quercetin is lowered by increased [ADP] and is increased by adenine nucleotide transporter inhibitor, atractyloside, but not bongkrekic acid. Both quercetin and dehydrosilybin dissipate mitochondrial membrane potential in whole cells. In the case of quercetin, the effect is potentiated post hypoxia. Genetically encoded Ca++ sensors, targeted to the mitochondria, enabled the use of fluorescence microscopy to show that quercetin decreased mitochondrial [Ca++] while dehydrosilybin did not. Likewise, quercetin decreases accumulation of [Ca++] in mitochondria following hypoxia. Fluorescent probes were used to show that both compounds decrease plasma membrane potential and increase cytosolic [Ca++]. We conclude that the uncoupler-like effects of these polyphenols are attenuated in whole cells compared to isolated mitochondria, but downstream effects are nevertheless apparent. Results suggest that the effect of quercetin observed in whole and permeabilised cells may originate in the mitochondria, while the mechanism of action of cardioprotection by dehydrosilybin may be less dependent on mitochondrial uncoupling than originally thought. Rather, protective effects may originate due to interactions at the plasma membrane. PMID:28977033

Correlation between uncoupled ATP hydrolysis and heat production by the sarcoplasmic reticulum Ca2+-ATPase: coupling effect of fluoride.

PubMed

Reis, M; Farage, M; de Souza, A C; de Meis, L

2001-11-16

The sarcoplasmic reticulum Ca(2+)-ATPase transports Ca(2+) using the chemical energy derived from ATP hydrolysis. Part of the chemical energy is used to translocate Ca(2+) through the membrane (work) and part is dissipated as heat. The amount of heat produced during catalysis increases after formation of the Ca(2+) gradient across the vesicle membrane. In the absence of gradient (leaky vesicles) the amount of heat produced/mol of ATP cleaved is half of that measured in the presence of the gradient. After formation of the gradient, part of the ATPase activity is not coupled to Ca(2+) transport. We now show that NaF can impair the uncoupled ATPase activity with discrete effect on the ATPase activity coupled to Ca(2+) transport. For the control vesicles not treated with NaF, after formation of the gradient only 20% of the ATP cleaved is coupled to Ca(2+) transport, and the caloric yield of the total ATPase activity (coupled plus uncoupled) is 22.8 kcal released/mol of ATP cleaved. In contrast, the vesicles treated with NaF consume only the ATP needed to maintain the gradient, and the caloric yield of ATP hydrolysis is 3.1 kcal/mol of ATP. The slow ATPase activity measured in vesicles treated with NaF has the same Ca(2+) dependence as the control vesicles. This demonstrates unambiguously that the uncoupled activity is an actual pathway of the Ca(2+)-ATPase rather than a contaminating phosphatase. We conclude that when ATP hydrolysis occurs without coupled biological work most of the chemical energy is dissipated as heat. Thus, uncoupled ATPase activity appears to be the mechanistic feature underlying the ability of the Ca(2+)-ATPase to modulated heat production.

Diamine-Appended Mg 2 (dobpdc) Nanorods as Phase-Change Fillers in Mixed-Matrix Membranes for Efficient CO 2/N 2 Separations

DOE PAGES

Maserati, Lorenzo; Meckler, Stephen M.; Bachman, Jonathan E.; ...

2017-10-18

Despite the availability of chemistries to tailor the pore architectures of microporous polymer membranes for chemical separations, trade-offs in permeability and selectivity with functional group manipulations nevertheless persist, which ultimately places an upper bound on membrane performance. We introduce a new design strategy to uncouple these attributes of the membrane. Key to our success is the incorporation of phase-change metal-organic frameworks (MOFs) into the polymer matrix, which can be used to increase the solubility of a specific gas in the membrane, and thereby its permeability. We further show that it is necessary to scale the size of the phase-change MOFmore » to nanoscopic dimensions, in order to take advantage of this effect in a gas separation. Our observation of an increase in solubility and permeability of only one of the gases during steady-state permeability measurements suggests fast exchange between free and chemisorbed gas molecules within the MOF pores. While the kinetics of this exchange in phase-change MOFs are not yet fully understood, their role in enhancing the efficacy and efficiency of the separation is clearly a compelling new direction for membrane technology.« less

Multi-step heater deployment in a subsurface formation

DOEpatents

Mason, Stanley Leroy [Allen, TX

2012-04-03

A method for installing a horizontal or inclined subsurface heater includes placing a heating section of a heater in a horizontal or inclined section of a wellbore with an installation tool. The tool is uncoupled from the heating section. A lead in section is mechanically and electrically coupled to the heating section of the heater. The lead-in section is located in an angled or vertical section of the wellbore.

Solving modal equations of motion with initial conditions using MSC/NASTRAN DMAP. Part 1: Implementing exact mode superposition

NASA Technical Reports Server (NTRS)

Abdallah, Ayman A.; Barnett, Alan R.; Ibrahim, Omar M.; Manella, Richard T.

1993-01-01

Within the MSC/NASTRAN DMAP (Direct Matrix Abstraction Program) module TRD1, solving physical (coupled) or modal (uncoupled) transient equations of motion is performed using the Newmark-Beta or mode superposition algorithms, respectively. For equations of motion with initial conditions, only the Newmark-Beta integration routine has been available in MSC/NASTRAN solution sequences for solving physical systems and in custom DMAP sequences or alters for solving modal systems. In some cases, one difficulty with using the Newmark-Beta method is that the process of selecting suitable integration time steps for obtaining acceptable results is lengthy. In addition, when very small step sizes are required, a large amount of time can be spent integrating the equations of motion. For certain aerospace applications, a significant time savings can be realized when the equations of motion are solved using an exact integration routine instead of the Newmark-Beta numerical algorithm. In order to solve modal equations of motion with initial conditions and take advantage of efficiencies gained when using uncoupled solution algorithms (like that within TRD1), an exact mode superposition method using MSC/NASTRAN DMAP has been developed and successfully implemented as an enhancement to an existing coupled loads methodology at the NASA Lewis Research Center.

Local complexity predicts global synchronization of hierarchically networked oscillators

NASA Astrophysics Data System (ADS)

Xu, Jin; Park, Dong-Ho; Jo, Junghyo

2017-07-01

We study the global synchronization of hierarchically-organized Stuart-Landau oscillators, where each subsystem consists of three oscillators with activity-dependent couplings. We considered all possible coupling signs between the three oscillators, and found that they can generate different numbers of phase attractors depending on the network motif. Here, the subsystems are coupled through mean activities of total oscillators. Under weak inter-subsystem couplings, we demonstrate that the synchronization between subsystems is highly correlated with the number of attractors in uncoupled subsystems. Among the network motifs, perfect anti-symmetric ones are unique to generate both single and multiple attractors depending on the activities of oscillators. The flexible local complexity can make global synchronization controllable.

Generalized Kapchinskij-Vladimirskij Distribution and Beam Matrix for Phase-Space Manipulations of High-Intensity Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, Moses; Qin, Hong; Davidson, Ronald C.

In an uncoupled linear lattice system, the Kapchinskij-Vladimirskij (KV) distribution formulated on the basis of the single-particle Courant-Snyder invariants has served as a fundamental theoretical basis for the analyses of the equilibrium, stability, and transport properties of high-intensity beams for the past several decades. Recent applications of high-intensity beams, however, require beam phase-space manipulations by intentionally introducing strong coupling. Here in this Letter, we report the full generalization of the KV model by including all of the linear (both external and space-charge) coupling forces, beam energy variations, and arbitrary emittance partition, which all form essential elements for phase-space manipulations. Themore » new generalized KV model yields spatially uniform density profiles and corresponding linear self-field forces as desired. Finally, the corresponding matrix envelope equations and beam matrix for the generalized KV model provide important new theoretical tools for the detailed design and analysis of high-intensity beam manipulations, for which previous theoretical models are not easily applicable.« less

Generalized Kapchinskij-Vladimirskij Distribution and Beam Matrix for Phase-Space Manipulations of High-Intensity Beams

DOE PAGES

Chung, Moses; Qin, Hong; Davidson, Ronald C.; ...

2016-11-23

In an uncoupled linear lattice system, the Kapchinskij-Vladimirskij (KV) distribution formulated on the basis of the single-particle Courant-Snyder invariants has served as a fundamental theoretical basis for the analyses of the equilibrium, stability, and transport properties of high-intensity beams for the past several decades. Recent applications of high-intensity beams, however, require beam phase-space manipulations by intentionally introducing strong coupling. Here in this Letter, we report the full generalization of the KV model by including all of the linear (both external and space-charge) coupling forces, beam energy variations, and arbitrary emittance partition, which all form essential elements for phase-space manipulations. Themore » new generalized KV model yields spatially uniform density profiles and corresponding linear self-field forces as desired. Finally, the corresponding matrix envelope equations and beam matrix for the generalized KV model provide important new theoretical tools for the detailed design and analysis of high-intensity beam manipulations, for which previous theoretical models are not easily applicable.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maserati, Lorenzo; Meckler, Stephen M.; Bachman, Jonathan E.

Despite the availability of chemistries to tailor the pore architectures of microporous polymer membranes for chemical separations, trade-offs in permeability and selectivity with functional group manipulations nevertheless persist, which ultimately places an upper bound on membrane performance. We introduce a new design strategy to uncouple these attributes of the membrane. Key to our success is the incorporation of phase-change metal-organic frameworks (MOFs) into the polymer matrix, which can be used to increase the solubility of a specific gas in the membrane, and thereby its permeability. We further show that it is necessary to scale the size of the phase-change MOFmore » to nanoscopic dimensions, in order to take advantage of this effect in a gas separation. Our observation of an increase in solubility and permeability of only one of the gases during steady-state permeability measurements suggests fast exchange between free and chemisorbed gas molecules within the MOF pores. While the kinetics of this exchange in phase-change MOFs are not yet fully understood, their role in enhancing the efficacy and efficiency of the separation is clearly a compelling new direction for membrane technology.« less

Derivation of equations of motion for multi-blade rotors employing coupled modes and including high twist capability

NASA Technical Reports Server (NTRS)

Sopher, R.

1975-01-01

The equations of motion are derived for a multiblade rotor. A high twist capability and coupled flatwise-edgewise assumed normal modes are employed instead of uncoupled flatwise - edgewise assumed normal models. The torsion mode is uncoupled. Support system models, consisting of complete helicopters in free flight, or grounded flexible supports, arbitrary rotor-induced inflow, and arbitrary vertical gust models are also used.

Short-term consumption of a high-fat diet impairs whole-body efficiency and cognitive function in sedentary men.

PubMed

Edwards, Lindsay M; Murray, Andrew J; Holloway, Cameron J; Carter, Emma E; Kemp, Graham J; Codreanu, Ion; Brooker, Helen; Tyler, Damian J; Robbins, Peter A; Clarke, Kieran

2011-03-01

We recently showed that a short-term high-fat diet blunted exercise performance in rats, accompanied by increased uncoupling protein levels and greater respiratory uncoupling. In this study, we investigated the effects of a similar diet on physical and cognitive performance in humans. Twenty sedentary men were assessed when consuming a standardized, nutritionally balanced diet (control) and after 7 d of consuming a diet comprising 74% kcal from fat. Efficiency was measured during a standardized exercise task, and cognition was assessed using a computerized assessment battery. Skeletal muscle mitochondrial function was measured using (31)P magnetic resonance spectroscopy. The diet increased mean ± se plasma free fatty acids by 44% (0.32±0.03 vs. 0.46±0.05 mM; P<0.05) and decreased whole-body efficiency by 3% (21±1 vs. 18±1%; P<0.05), although muscle uncoupling protein (UCP3) content and maximal mitochondrial function were unchanged. High-fat diet consumption also increased subjects' simple reaction times (P<0.01) and decreased power of attention (P<0.01). Thus, we have shown that a high-fat diet blunts whole-body efficiency and cognition in sedentary men. We suggest that this effect may be due to increased respiratory uncoupling.

On the effect of acoustic coupling on random and harmonic plate vibrations

NASA Technical Reports Server (NTRS)

Frendi, A.; Robinson, J. H.

1993-01-01

The effect of acoustic coupling on random and harmonic plate vibrations is studied using two numerical models. In the coupled model, the plate response is obtained by integration of the nonlinear plate equation coupled with the nonlinear Euler equations for the surrounding acoustic fluid. In the uncoupled model, the nonlinear plate equation with an equivalent linear viscous damping term is integrated to obtain the response of the plate subject to the same excitation field. For a low-level, narrow-band excitation, the two models predict the same plate response spectra. As the excitation level is increased, the response power spectrum predicted by the uncoupled model becomes broader and more shifted towards the high frequencies than that obtained by the coupled model. In addition, the difference in response between the coupled and uncoupled models at high frequencies becomes larger. When a high intensity harmonic excitation is used, causing a nonlinear plate response, both models predict the same frequency content of the response. However, the level of the harmonics and subharmonics are higher for the uncoupled model. Comparisons to earlier experimental and numerical results show that acoustic coupling has a significant effect on the plate response at high excitation levels. Its absence in previous models may explain the discrepancy between predicted and measured responses.

Salsalate (Salicylate) Uncouples Mitochondria, Improves Glucose Homeostasis, and Reduces Liver Lipids Independent of AMPK-β1

PubMed Central

Smith, Brennan K.; Ford, Rebecca J.; Desjardins, Eric M.; Green, Alex E.; Hughes, Meghan C.; Houde, Vanessa P.; Day, Emily A.; Marcinko, Katarina; Crane, Justin D.; Mottillo, Emilio P.; Perry, Christopher G.R.; Kemp, Bruce E.; Tarnopolsky, Mark A.; Steinberg, Gregory R.

2017-01-01

Salsalate is a prodrug of salicylate that lowers blood glucose in patients with type 2 diabetes (T2D) and reduces nonalcoholic fatty liver disease (NAFLD) in animal models; however, the mechanism mediating these effects is unclear. Salicylate directly activates AMPK via the β1 subunit, but whether salsalate requires AMPK-β1 to improve T2D and NAFLD has not been examined. Therefore, wild-type (WT) and AMPK-β1–knockout (AMPK-β1KO) mice were treated with a salsalate dose resulting in clinically relevant serum salicylate concentrations (~1 mmol/L). Salsalate treatment increased VO2, lowered fasting glucose, improved glucose tolerance, and led to an ~55% reduction in liver lipid content. These effects were observed in both WT and AMPK-β1KO mice. To explain these AMPK-independent effects, we found that salicylate increases oligomycin-insensitive respiration (state 4o) and directly increases mitochondrial proton conductance at clinical concentrations. This uncoupling effect is tightly correlated with the suppression of de novo lipogenesis. Salicylate is also able to stimulate brown adipose tissue respiration independent of uncoupling protein 1. These data indicate that the primary mechanism by which salsalate improves glucose homeostasis and NAFLD is via salicylate-driven mitochondrial uncoupling. PMID:27554471

Role of Dietary Antioxidants in the Preservation of Vascular Function and the Modulation of Health and Disease

PubMed Central

Varadharaj, Saradhadevi; Kelly, Owen J.; Khayat, Rami N.; Kumar, Purnima S.; Ahmed, Naseer; Zweier, Jay L.

2017-01-01

In vascular diseases, including hypertension and atherosclerosis, vascular endothelial dysfunction (VED) occurs secondary to altered function of endothelial nitric oxide synthase (eNOS). A novel redox regulated pathway was identified through which eNOS is uncoupled due to S-glutathionylation of critical cysteine residues, resulting in superoxide free radical formation instead of the vasodilator molecule, nitric oxide. In addition, the redox sensitive cofactor tetrahydrobiopterin, BH4, is also essential for eNOS coupling. Antioxidants, either individually or combined, can modulate eNOS uncoupling by scavenging free radicals or impairing specific radical generating pathways, thus preventing oxidative stress and ameliorating VED. Epidemiological evidence and dietary guidelines suggest that diets high in antioxidants, or antioxidant supplementation, could preserve vascular health and prevent cardiovascular diseases (CVDs). Therefore, the purpose of this review is to highlight the possible role of dietary antioxidants in regulating eNOS function and uncoupling which is critical for maintenance of vascular health with normal blood flow/circulation and prevention of VED. We hypothesize that a conditioned dietary approach with suitable antioxidants may limit systemic oxidation, maintain a beneficial ratio of reduced to oxidized glutathione, and other redox markers, and minimize eNOS uncoupling serving to prevent CVD and possibly other chronic diseases. PMID:29164133

Influence of stochastic sea ice parametrization on climate and the role of atmosphere–sea ice–ocean interaction

PubMed Central

Juricke, Stephan; Jung, Thomas

2014-01-01

The influence of a stochastic sea ice strength parametrization on the mean climate is investigated in a coupled atmosphere–sea ice–ocean model. The results are compared with an uncoupled simulation with a prescribed atmosphere. It is found that the stochastic sea ice parametrization causes an effective weakening of the sea ice. In the uncoupled model this leads to an Arctic sea ice volume increase of about 10–20% after an accumulation period of approximately 20–30 years. In the coupled model, no such increase is found. Rather, the stochastic perturbations lead to a spatial redistribution of the Arctic sea ice thickness field. A mechanism involving a slightly negative atmospheric feedback is proposed that can explain the different responses in the coupled and uncoupled system. Changes in integrated Antarctic sea ice quantities caused by the stochastic parametrization are generally small, as memory is lost during the melting season because of an almost complete loss of sea ice. However, stochastic sea ice perturbations affect regional sea ice characteristics in the Southern Hemisphere, both in the uncoupled and coupled model. Remote impacts of the stochastic sea ice parametrization on the mean climate of non-polar regions were found to be small. PMID:24842027

Clusianone, a naturally occurring nemorosone regioisomer, uncouples rat liver mitochondria and induces HepG2 cell death.

PubMed

Reis, Felippe H Z; Pardo-Andreu, Gilberto L; Nuñez-Figueredo, Yanier; Cuesta-Rubio, Osmany; Marín-Prida, Javier; Uyemura, Sérgio A; Curti, Carlos; Alberici, Luciane C

2014-04-05

Clusianone is a member of the polycyclic polyprenylated acylphloroglucinol family of natural products; its cytotoxic mechanism is unknown. Clusianone is a structural isomer of nemorosone, which is a mitochondrial uncoupler and a well-known cytotoxic anti-cancer agent; thus, we addressed clusianone action at the mitochondria and its potential cytotoxic effects on cancer cells. In the HepG2 hepatocarcinoma cell line, clusianone induced mitochondrial membrane potential dissipation, ATP depletion and phosphatidyl serine externalization; this later event is indicative of apoptosis induction. In isolated mitochondria from rat liver, clusianone promoted protonophoric mitochondrial uncoupling. This was evidenced by the dissipation of mitochondrial membrane potential, an increase in resting respiration, an inhibition of Ca(2+) influx, stimulation of Ca(2+) efflux in Ca(2+)-loaded mitochondria, a decrease in ATP and NAD(P)H levels, generation of ROS, and swelling of valinomycin-treated organelles in hyposmotic potassium acetate media. The cytotoxic and uncoupling actions of clusianone were appreciably less than those of nemorosone, likely due to the presence of an intra-molecular hydrogen bond with the juxtaposed carbonyl group at the C15 position. Therefore, clusianone is capable of pharmacologically increasing the leakage of protons from the mitochondria and with favorable cytotoxicity in relation to nemorosone. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

ZmPUMP encodes a fully functional monocot plant uncoupling mitochondrial protein whose affinity to fatty acid is increased with the introduction of a His pair at the second matrix loop

DOE Office of Scientific and Technical Information (OSTI.GOV)

Favaro, Regiane Degan; Borecky, Jiri; Colombi, Debora

Uncoupling proteins (UCPs) are specialized mitochondrial transporter proteins that uncouple respiration from ATP synthesis. In this study, cDNA encoding maize uncoupling protein (ZmPUMP) was expressed in Escherichia coli and recombinant ZmPUMP reconstituted in liposomes. ZmPUMP activity was associated with a linoleic acid (LA)-mediated H{sup +} efflux with K {sub m} of 56.36 {+-} 0.27 {mu}M and V {sub max} of 66.9 {mu}mol H{sup +} min{sup -1} (mg prot){sup -1}. LA-mediated H{sup +} fluxes were sensitive to ATP inhibition with K {sub i} of 2.61 {+-} 0.36 mM (at pH 7.2), a value similar to those for dicot UCPs. ZmPUMP wasmore » also used to investigate the importance of a histidine pair present in the second matrix loop of mammalian UCP1 and absent in plant UCPs. ZmPUMP with introduced His pair (Lys155His and Ala157His) displayed a 1.55-fold increase in LA-affinity while its activity remained unchanged. Our data indicate conserved properties of plant UCPs and suggest an enhancing but not essential role of the histidine pair in proton transport mechanism.« less

Unifying concept of serotonin transporter-associated currents.

PubMed

Schicker, Klaus; Uzelac, Zeljko; Gesmonde, Joan; Bulling, Simon; Stockner, Thomas; Freissmuth, Michael; Boehm, Stefan; Rudnick, Gary; Sitte, Harald H; Sandtner, Walter

2012-01-02

Serotonin (5-HT) uptake by the human serotonin transporter (hSERT) is driven by ion gradients. The stoichiometry of transported 5-HT and ions is predicted to result in electroneutral charge movement. However, hSERT mediates a current when challenged with 5-HT. This discrepancy can be accounted for by an uncoupled ion flux. Here, we investigated the mechanistic basis of the uncoupled currents and its relation to the conformational cycle of hSERT. Our observations support the conclusion that the conducting state underlying the uncoupled ion flux is in equilibrium with an inward facing state of the transporter with K+ bound. We identified conditions associated with accumulation of the transporter in inward facing conformations. Manipulations that increased the abundance of inward facing states resulted in enhanced steady-state currents. We present a comprehensive kinetic model of the transport cycle, which recapitulates salient features of the recorded currents. This study provides a framework for exploring transporter-associated currents.

Unifying Concept of Serotonin Transporter-associated Currents*

PubMed Central

Schicker, Klaus; Uzelac, Zeljko; Gesmonde, Joan; Bulling, Simon; Stockner, Thomas; Freissmuth, Michael; Boehm, Stefan; Rudnick, Gary; Sitte, Harald H.; Sandtner, Walter

2012-01-01

Serotonin (5-HT) uptake by the human serotonin transporter (hSERT) is driven by ion gradients. The stoichiometry of transported 5-HT and ions is predicted to result in electroneutral charge movement. However, hSERT mediates a current when challenged with 5-HT. This discrepancy can be accounted for by an uncoupled ion flux. Here, we investigated the mechanistic basis of the uncoupled currents and its relation to the conformational cycle of hSERT. Our observations support the conclusion that the conducting state underlying the uncoupled ion flux is in equilibrium with an inward facing state of the transporter with K+ bound. We identified conditions associated with accumulation of the transporter in inward facing conformations. Manipulations that increased the abundance of inward facing states resulted in enhanced steady-state currents. We present a comprehensive kinetic model of the transport cycle, which recapitulates salient features of the recorded currents. This study provides a framework for exploring transporter-associated currents. PMID:22072712

Distinct mechanisms determine organ left-right asymmetry patterning in an uncoupled way.

PubMed

Huang, Sizhou; Xu, Wenming; Su, Bingyin; Luo, Lingfei

2014-03-01

Disruption of Nodal in the lateral plate mesoderm (LPM) usually leads to left-right (LR) patterning defects in multiple organs. However, whether the LR patterning of organs is always regulated in a coupled way has largely not yet been elucidated. In addition, whether other crucial regulators exist in the LPM that coordinate with Nodal in regulating organ LR patterning is also undetermined. In this paper, after briefly summarizing the common process of LR patterning, the most puzzling question regarding the initiation of asymmetry is considered and the divergent mechanisms underlying the uncoupled LR patterning in different organs are discussed. On the basis of cases in which different organ LR patterning is determined in an uncoupled way via an independent mechanism or at a different time, we propose that there are other critical factors in the LPM that coordinate with Nodal to regulate heart LR asymmetry patterning during early LR patterning. © 2014 WILEY Periodicals, Inc.

Temperature controls oxidative phosphorylation and reactive oxygen species production through uncoupling in rat skeletal muscle mitochondria.

PubMed

Jarmuszkiewicz, Wieslawa; Woyda-Ploszczyca, Andrzej; Koziel, Agnieszka; Majerczak, Joanna; Zoladz, Jerzy A

2015-06-01

Mitochondrial respiratory and phosphorylation activities, mitochondrial uncoupling, and hydrogen peroxide formation were studied in isolated rat skeletal muscle mitochondria during experimentally induced hypothermia (25 °C) and hyperthermia (42 °C) compared to the physiological temperature of resting muscle (35 °C). For nonphosphorylating mitochondria, increasing the temperature from 25 to 42 °C led to a decrease in membrane potential, hydrogen peroxide production, and quinone reduction levels. For phosphorylating mitochondria, no temperature-dependent changes in these mitochondrial functions were observed. However, the efficiency of oxidative phosphorylation decreased, whereas the oxidation and phosphorylation rates and oxidative capacities of the mitochondria increased, with increasing assay temperature. An increase in proton leak, including uncoupling protein-mediated proton leak, was observed with increasing assay temperature, which could explain the reduced oxidative phosphorylation efficiency and reactive oxygen species production. Copyright © 2015 Elsevier Inc. All rights reserved.

Lipotoxicity, fatty acid uncoupling and mitochondrial carrier function.

PubMed

Rial, Eduardo; Rodríguez-Sánchez, Leonor; Gallardo-Vara, Eunate; Zaragoza, Pilar; Moyano, Eva; González-Barroso, M Mar

2010-01-01

Diseases like obesity, diabetes or generalized lipodystrophy cause a chronic elevation of circulating fatty acids that can become cytotoxic, a condition known as lipotoxicity. Fatty acids cause oxidative stress and alterations in mitochondrial structure and function. The uncoupling of the oxidative phosphorylation is one of the most recognized deleterious fatty acid effects and several metabolite transporters are known to mediate in their action. The fatty acid interaction with the carriers leads to membrane depolarization and/or the conversion of the carrier into a pore. The result is the opening of the permeability transition pore and the initiation of apoptosis. Unlike the other members of the mitochondrial carrier superfamily, the eutherian uncoupling protein UCP1 has evolved to achieve its heat-generating capacity in the physiological context provided by the brown adipocyte and therefore it is activated by the low fatty acid concentrations generated by the noradrenaline-stimulated lipolysis. Copyright © 2010 Elsevier B.V. All rights reserved.

The Stimulated Glycolytic Pathway Is Able to Maintain ATP Levels and Kinetic Patterns of Bovine Epididymal Sperm Subjected to Mitochondrial Uncoupling.

PubMed

Losano, João D A; Padín, Juan Fernando; Méndez-López, Iago; Angrimani, Daniel S R; García, Antonio G; Barnabe, Valquiria H; Nichi, Marcilio

2017-01-01

Studies have reported the importance of mitochondria in sperm functionality. However, for some species, the glycolytic pathway appears to be as important as oxidative phosphorylation in ATP synthesis and sperm kinetics. These mechanisms have not been fully elucidated for bovine spermatozoa. Therefore, the aim of this study was to evaluate the role of mitochondria and the glycolytic pathway in ATP synthesis, sperm movement patterns, and oxidative homeostasis of epididymal spermatozoa in bovine specimens. We observed that mitochondrial uncoupling with protonophores significantly reduced ATP levels. However, these levels were reestablished after stimulation of the glycolytic pathway. We verified the same pattern of results for sperm kinetic variables and the production of reactive oxygen species (ROS). Thus, we suggest that, after its appropriate stimulation, the glycolytic pathway is capable of maintaining ATP levels, sperm kinetic patterns, and oxidative balance of bovine epididymal spermatozoa submitted to mitochondrial uncoupling.

Uncoupling and oxidative stress in liver mitochondria isolated from rats with acute iron overload.

PubMed

Pardo Andreu, G L; Inada, N M; Vercesi, A E; Curti, C

2009-01-01

One hypothesis for the etiology of cell damage arising from iron overload is that its excess selectively affects mitochondria. Here we tested the effects of acute iron overload on liver mitochondria isolated from rats subjected to a single dose of i.p. 500 mg/kg iron-dextran. The treatment increased the levels of iron in mitochondria (from 21 +/- 4 to 130 +/- 7 nmol/mg protein) and caused both lipid peroxidation and glutathione oxidation. The mitochondria of iron-treated rats showed lower respiratory control ratio in association with higher resting respiration. The mitochondrial uncoupling elicited by iron-treatment did not affect the phosphorylation efficiency or the ATP levels, suggesting that uncoupling is a mitochondrial protective mechanism against acute iron overload. Therefore, the reactive oxygen species (ROS)/H+ leak couple, functioning as a mitochondrial redox homeostatic mechanism could play a protective role in the acutely iron-loaded mitochondria.

Brown fat in a protoendothermic mammal fuels eutherian evolution.

PubMed

Oelkrug, Rebecca; Goetze, Nadja; Exner, Cornelia; Lee, Yang; Ganjam, Goutham K; Kutschke, Maria; Müller, Saskia; Stöhr, Sigrid; Tschöp, Matthias H; Crichton, Paul G; Heldmaier, Gerhard; Jastroch, Martin; Meyer, Carola W

2013-01-01

Endothermy has facilitated mammalian species radiation, but the sequence of events leading to sustained thermogenesis is debated in multiple evolutionary models. Here we study the Lesser hedgehog tenrec (Echinops telfairi), a phylogenetically ancient, 'protoendothermic' eutherian mammal, in which constantly high body temperatures are reported only during reproduction. Evidence for nonshivering thermogenesis is found in vivo during periodic ectothermic-endothermic transitions. Anatomical studies reveal large brown fat-like structures in the proximity of the reproductive organs, suggesting physiological significance for parental care. Biochemical analysis demonstrates high mitochondrial proton leak catalysed by an uncoupling protein 1 ortholog. Strikingly, bioenergetic profiling of tenrec uncoupling protein 1 reveals similar thermogenic potency as modern mouse uncoupling protein 1, despite the large phylogenetic distance. The discovery of functional brown adipose tissue in this 'protoendothermic' mammal links nonshivering thermogenesis directly to the roots of eutherian evolution, suggesting physiological importance prior to sustained body temperatures and migration to the cold.

Brown fat in a protoendothermic mammal fuels eutherian evolution

PubMed Central

Oelkrug, Rebecca; Goetze, Nadja; Exner, Cornelia; Lee, Yang; Ganjam, Goutham K.; Kutschke, Maria; Müller, Saskia; Stöhr, Sigrid; Tschöp, Matthias H.; Crichton, Paul G.; Heldmaier, Gerhard; Jastroch, Martin; Meyer, Carola W.

2013-01-01

Endothermy has facilitated mammalian species radiation, but the sequence of events leading to sustained thermogenesis is debated in multiple evolutionary models. Here we study the Lesser hedgehog tenrec (Echinops telfairi), a phylogenetically ancient, ‘protoendothermic’ eutherian mammal, in which constantly high body temperatures are reported only during reproduction. Evidence for nonshivering thermogenesis is found in vivo during periodic ectothermic–endothermic transitions. Anatomical studies reveal large brown fat-like structures in the proximity of the reproductive organs, suggesting physiological significance for parental care. Biochemical analysis demonstrates high mitochondrial proton leak catalysed by an uncoupling protein 1 ortholog. Strikingly, bioenergetic profiling of tenrec uncoupling protein 1 reveals similar thermogenic potency as modern mouse uncoupling protein 1, despite the large phylogenetic distance. The discovery of functional brown adipose tissue in this ‘protoendothermic’ mammal links nonshivering thermogenesis directly to the roots of eutherian evolution, suggesting physiological importance prior to sustained body temperatures and migration to the cold. PMID:23860571

Structural Sensitivity of a Prokaryotic Pentameric Ligand-gated Ion Channel to Its Membrane Environment*

PubMed Central

Labriola, Jonathan M.; Pandhare, Akash; Jansen, Michaela; Blanton, Michael P.; Corringer, Pierre-Jean; Baenziger, John E.

2013-01-01

Although the activity of the nicotinic acetylcholine receptor (nAChR) is exquisitely sensitive to its membrane environment, the underlying mechanisms remain poorly defined. The homologous prokaryotic pentameric ligand-gated ion channel, Gloebacter ligand-gated ion channel (GLIC), represents an excellent model for probing the molecular basis of nAChR sensitivity because of its high structural homology, relative ease of expression, and amenability to crystallographic analysis. We show here that membrane-reconstituted GLIC exhibits structural and biophysical properties similar to those of the membrane-reconstituted nAChR, although GLIC is substantially more thermally stable. GLIC, however, does not possess the same exquisite lipid sensitivity. In particular, GLIC does not exhibit the same propensity to adopt an uncoupled conformation where agonist binding is uncoupled from channel gating. Structural comparisons provide insight into the chemical features that may predispose the nAChR to the formation of an uncoupled state. PMID:23463505

Uncoupling of reading and IQ over time: empirical evidence for a definition of dyslexia.

PubMed

Ferrer, Emilio; Shaywitz, Bennett A; Holahan, John M; Marchione, Karen; Shaywitz, Sally E

2010-01-01

Developmental dyslexia is defined as an unexpected difficulty in reading in individuals who otherwise possess the intelligence and motivation considered necessary for fluent reading, and who also have had reasonable reading instruction. Identifying factors associated with normative and impaired reading development has implications for diagnosis, intervention, and prevention. We show that in typical readers, reading and IQ development are dynamically linked over time. Such mutual interrelationships are not perceptible in dyslexic readers, which suggests that reading and cognition develop more independently in these individuals. To our knowledge, these findings provide the first empirical demonstration of a coupling between cognition and reading in typical readers and a developmental uncoupling between cognition and reading in dyslexic readers. This uncoupling was the core concept of the initial description of dyslexia and remains the focus of the current definitional model of this learning disability.

Highly Efficient Oxygen-Storage Material with Intrinsic Coke Resistance for Chemical Looping Combustion-Based CO2 Capture.

PubMed

Imtiaz, Qasim; Kurlov, Alexey; Rupp, Jennifer Lilia Marguerite; Müller, Christoph Rüdiger

2015-06-22

Chemical looping combustion (CLC) and chemical looping with oxygen uncoupling (CLOU) are emerging thermochemical CO2 capture cycles that allow the capture of CO2 with a small energy penalty. Here, the development of suitable oxygen carrier materials is a key aspect to transfer these promising concepts to practical installations. CuO is an attractive material for CLC and CLOU because of its high oxygen-storage capacity (20 wt %), fast reaction kinetics, and high equilibrium partial pressure of oxygen at typical operating temperatures (850-1000 °C). However, despite its promising characteristics, its low Tammann temperature requires the development of new strategies to phase-stabilize CuO-based oxygen carriers. In this work, we report a strategy based on stabilization by co-precipitated ceria (CeO2-x ), which allowed us to increase the oxygen capacity, coke resistance, and redox stability of CuO-based oxygen carriers substantially. The performance of the new oxygen carriers was evaluated in detail and compared to the current state-of-the-art materials, that is, Al2 O3 -stabilized CuO with similar CuO loadings. We also demonstrate that the higher intrinsic oxygen uptake, release, and mobility in CeO2-x -stabilized CuO leads to a three times higher carbon deposition resistance compared to that of Al2 O3 -stabilized CuO. Moreover, we report a high cyclic stability without phase intermixing for CeO2-x -supported CuO. This was accompanied by a lower reduction temperature compared to state-of-the-art Al2 O3 -supported CuO. As a result of its high resistance towards carbon deposition and fast oxygen uncoupling kinetics, CeO2-x -stabilized CuO is identified as a very promising material for CLC- and CLOU-based CO2 capture architectures. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rational Design of Mixed-Metal Oxides for Chemical Looping Combustion of Coal via Coupled Computational-Experimental Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, Amit; Li, Fanxing; Santiso, Erik

Energy and global climate change are two grand challenges to the modern society. An urgent need exists for development of clean and efficient energy conversion processes. The chemical looping strategy, which utilizes regenerable oxygen carriers (OCs) to indirectly convert carbonaceous fuels via redox reactions, is considered to be one of the more promising approaches for CO2 capture by the U.S. Department of Energy (USDOE). To date, most long-term chemical looping operations were conducted using gaseous fuels, even though direct conversion of coal is more desirable from both economics and CO2 capture viewpoints. The main challenges for direct coal conversion residemore » in the stringent requirements on oxygen carrier performances. In addition, coal char and volatile compounds are more challenging to convert than gaseous fuels. A promising approach for direct conversion of coal is the so called chemical looping with oxygen uncoupling (CLOU) technique. In the CLOU process, a metal oxide that decomposes at the looping temperature, and releases oxygen to the gas phase is used as the OC. The overarching objective of this project was to discover the fundamental principles for rational design and optimization of oxygen carriers (OC) in coal chemical looping combustion (CLC) processes. It directly addresses Topic Area B of the funding opportunity announcement (FOA) in terms of “predictive description of the phase behavior and mechanical properties” of “mixed metal oxide” based OCs and rational development of new OC materials with superior functionality. This was achieved through studies exploring i) iron-containing mixed-oxide composites as oxygen carriers for CLOU, ii) Ca1-xAxMnO3-δ (A = Sr and Ba) as oxygen carriers for CLOU, iii) CaMn1-xBxO3-δ (B=Al, V, Fe, Co, and Ni) as oxygen carrier for CLOU and iv) vacancy creation energy in Mn-containing perovskites as an indicator chemical looping with oxygen uncoupling.« less

The mRNA expression levels of uncoupling proteins 1 and 2 in mononuclear cells from patients with metabolic disorders: obesity and type 2 diabetes mellitus.

PubMed

Margaryan, Sona; Witkowicz, Agata; Partyka, Anna; Yepiskoposyan, Levon; Manukyan, Gayane; Karabon, Lidia

2017-10-19

Type 2 diabetes mellitus (T2DM) and obesity are metabolic disorders whose major hallmark is insulin resistance. Impaired mitochondrial activity, such as reduced ratio of energy production to respiration, has been implicated in the development of insulin resistance. Uncoupling proteins (UCPs) are proton carriers, expressed in the mitochondrial inner membrane, that uncouple oxygen consumption by the respiratory chain from ATP synthesis. The aim of the study was to determine transcriptional levels of UCP1 and UCP2 in peripheral blood mononuclear cells (PBMCs) from patients with metabolic disorders: T2DM, obesity and from healthy individuals. The mRNA levels of UCP1, UCP2 were determined by Real-Time PCR method using Applied Biosystems assays. The UCP1 mRNA expression level was not detectable in the majority of studied samples, while very low expression was found in PBMCs from 3 obese persons. UCP2 mRNA expression level was detectable in all samples. The median mRNA expression of UCP2 was lower in all patients with metabolic disorders as compared to the controls (0.20+0.14 vs. 0.010+0.009, p=0.05). When compared separately, the differences of medians UCP2 mRNA expression level between the obese individuals and the controls as well as between the T2DM patients and the controls did not reach statistical significance. Decreased UCP2 gene expression in mononuclear cells from obese and diabetic patients might contribute to the immunological abnormalities in these metabolic disorders and suggests its role as a candidate gene in future studies of obesity and diabetes.

Involvement of oxygen free radicals in the respiratory uncoupling induced by free calcium and ADP-magnesium in isolated cardiac mitochondria: comparing reoxygenation in cultured cardiomyocytes.

PubMed

Meynier, Alexandra; Razik, Hafida; Cordelet, Catherine; Grégoire, Stéphane; Demaison, Luc

2003-01-01

Recently, we have observed that the simultaneous application of free calcium (fCa) and ADP-magnesium (Mg) reduced the ADP:O ratio in isolated cardiac mitochondria. The uncoupling was prevented by cyclosporin A, an inhibitor of the permeability transition pore. The purpose of this study was to know if the generation of oxygen free radicals (OFR) is involved in this phenomenon and if it occurs during reoxygenation (Reox) of cultured cardiomyocytes. Cardiac mitochondria were harvested from male Wistar rats. Respiration was assessed in two media with different fCa concentrations (0 or 0.6 microM) with palmitoylcarnitine and ADP-Mg as respiration substrates. The production of Krebs cycle intermediates (KCI) was determined. Without fCa in the medium, the mitochondria displayed a large production of citrate + isocitrate + alpha-ketoglutarate. fCa drastically reduced these KCI and promoted the accumulation of succinate. To know if OFR are involved in the respiratory uncoupling, the effect of 4OH-TEMPO (250 microM), a hydrosoluble scavenger of OFR, was tested. 4OH-TEMPO completely abolished the fCa- and ADP-Mg-induced uncoupling. Conversely, vitamin E contributed to further decreasing the ADP:O ratio. Since no hydrosoluble electron acceptor was added in our experiment, the oxygen free radical-induced oxidized vitamin E was confined near the mitochondrial membranes, which should reduce the ADP:O ratio by opening the permeability transition pore. The generation of OFR could result from the matrix accumulation of succinate. Taken together, these results indicate that mitochondrial Ca uptake induces a slight increase in membrane permeability. Thereafter, Mg enters the matrix and, in combination with Ca, stimulates the isocitrate and/or alpha-ketoglutarate dehydrogenases. Matrix succinate favors oxygen free radical generation that further increases membrane permeability and allows respiratory uncoupling through proton leakage. To determine whether the phenomenon takes place during Reox, cultured cardiomyocytes were subjected to hypoxia and Reox. 14C-palmitate was added during Reox to determine the KCI profile. Succinate had not increased during Reox. In conclusion, calcium- and ADP-Mg-induced respiratory uncoupling is due to oxygen free radical generation through excess matrix accumulation of succinate. The phenomenon does not occur during reoxygenation because of a total restoration of mitochondrial magnesium and/or ADP concentration.

Achromatic and uncoupled medical gantry

DOEpatents

Tsoupas, Nicholaos [Center Moriches, NY; Kayran, Dmitry [Rocky Point, NY; Litvinenko, Vladimir [Mt. Sinai, NY; MacKay, William W [Wading River, NY

2011-11-22

A medical gantry that focus the beam from the beginning of the gantry to the exit of the gantry independent of the rotation angle of the gantry by keeping the beam achromatic and uncoupled, thus, avoiding the use of collimators or rotators, or additional equipment to control the beam divergence, which may cause beam intensity loss or additional time in irradiation of the patient, or disadvantageously increase the overall gantry size inapplicable for the use in the medical treatment facility.

Overexpression of uncoupling protein-2 in cancer: metabolic and heat changes, inhibition and effects on drug resistance.

PubMed

Pitt, Michael A

2015-12-01

This paper deals with the role of uncoupling protein-2 (UCP2) in cancer. UCP2 is overexpressed in cancer. This overexpression results in uncoupling of mitochondrial oxidative phosphorylation and a shift in production of ATP from mitochondrial oxidative phosphorylation to cytosolic aerobic glycolysis. UCP2 overexpression results in the following changes. Mitochondrial membrane potential (Δψ(m)) is decreased and lactate accumulates. There is a diminished production of reactive oxygen species and apoptosis is inhibited post-exposure to chemotherapeutic agents. There is an increase in heat and entropy production and a departure from the stationary state of non-cancerous tissue. Uncoupling of oxidative phosphorylation may also be caused by protonophores and non-steroidal anti-inflammatory drugs. UCP2 requires activation by superoxide and lipid peroxidation derivatives. As vitamin E inhibits lipid peroxidation, it might be expected that vitamin E would act as a chemotherapeutic agent against cancer. A recent study has shown that vitamin E and another anti-oxidant accelerate cancer progression. UCP2 is inhibited by genipin, chromane compounds and short interfering RNAs (siRNA). Genipin, chromanes and siRNA are taken up by both cancer and non-cancerous cells. Targeting the uptake of these agents by cancer cells by the enhanced permeability and retention effect is considered. Inhibition of UCP2 enhances the action of several anti-cancer agents.

Application of a personal computer for the uncoupled vibration analysis of wind turbine blade and counterweight assemblies

NASA Technical Reports Server (NTRS)

White, P. R.; Little, R. R.

1985-01-01

A research effort was undertaken to develop personal computer based software for vibrational analysis. The software was developed to analytically determine the natural frequencies and mode shapes for the uncoupled lateral vibrations of the blade and counterweight assemblies used in a single bladed wind turbine. The uncoupled vibration analysis was performed in both the flapwise and chordwise directions for static rotor conditions. The effects of rotation on the uncoupled flapwise vibration of the blade and counterweight assemblies were evaluated for various rotor speeds up to 90 rpm. The theory, used in the vibration analysis codes, is based on a lumped mass formulation for the blade and counterweight assemblies. The codes are general so that other designs can be readily analyzed. The input for the codes is generally interactive to facilitate usage. The output of the codes is both tabular and graphical. Listings of the codes are provided. Predicted natural frequencies of the first several modes show reasonable agreement with experimental results. The analysis codes were originally developed on a DEC PDP 11/34 minicomputer and then downloaded and modified to run on an ITT XTRA personal computer. Studies conducted to evaluate the efficiency of running the programs on a personal computer as compared with the minicomputer indicated that, with the proper combination of hardware and software options, the efficiency of using a personal computer exceeds that of a minicomputer.

Myocardial architecture and patient variability in clinical patterns of atrial fibrillation

NASA Astrophysics Data System (ADS)

Manani, Kishan A.; Christensen, Kim; Peters, Nicholas S.

2016-10-01

Atrial fibrillation (AF) increases the risk of stroke by a factor of 4-5 and is the most common abnormal heart rhythm. The progression of AF with age, from short self-terminating episodes to persistence, varies between individuals and is poorly understood. An inability to understand and predict variation in AF progression has resulted in less patient-specific therapy. Likewise, it has been a challenge to relate the microstructural features of heart muscle tissue (myocardial architecture) with the emergent temporal clinical patterns of AF. We use a simple model of activation wave-front propagation on an anisotropic structure, mimicking heart muscle tissue, to show how variation in AF behavior arises naturally from microstructural differences between individuals. We show that the stochastic nature of progressive transversal uncoupling of muscle strands (e.g., due to fibrosis or gap junctional remodeling), as occurs with age, results in variability in AF episode onset time, frequency, duration, burden, and progression between individuals. This is consistent with clinical observations. The uncoupling of muscle strands can cause critical architectural patterns in the myocardium. These critical patterns anchor microreentrant wave fronts and thereby trigger AF. It is the number of local critical patterns of uncoupling as opposed to global uncoupling that determines AF progression. This insight may eventually lead to patient-specific therapy when it becomes possible to observe the cellular structure of a patient's heart.

Diagnosing Air-Sea Interactions on Intraseasonal Timescales

NASA Astrophysics Data System (ADS)

DeMott, C. A.

2014-12-01

What is the role of ocean coupling in the Madden Julian Oscillation (MJO)? Consensus thinking holds that the essential physics of the MJO involve interactions between convection, atmospheric wave dynamics, and boundary layer and free troposphere moisture. However, many modeling studies demonstrate improved MJO simulation when an atmosphere-only general circulation model (AGCM) is coupled to an ocean model, so feedbacks from the ocean are probably not negligible. Assessing the importance and processes of these feedbacks is challenging for at least two reasons. First, observations of the MJO only sample the fully coupled ocean-atmosphere system; there is no "uncoupled" MJO in nature. Second, the practice of analyzing the MJO in uncoupled and coupled GCMs (CGCMs) involves using imperfect tools to study the problem. Although MJO simulation is improving in many models, shortcomings remain in both AGCMs and CGCMs, making it difficult to determine if changes brought about through coupling reflect critical air-sea interactions or are simply part of the collective idiosyncracies of a given model. For the atmosphere, ocean feedbacks from intraseasonal sea surface temperature (SST) variations are communicated through their effects on surface fluxes of heat and moisture. This presentation suggests a set of analysis tools for diagnosing the impact of an interactive ocean on surface latent and sensible heat fluxes, including their mean, variance, spectral characteristics, and phasing with respect to wind, SST, and MJO convection. The diagnostics are demonstrated with application to several CMIP5 models, and reveal a variety of responses to coupled ocean feedbacks.

Positive Feedback Keeps Duration of Mitosis Temporally Insulated from Upstream Cell-Cycle Events.

PubMed

Araujo, Ana Rita; Gelens, Lendert; Sheriff, Rahuman S M; Santos, Silvia D M

2016-10-20

Cell division is characterized by a sequence of events by which a cell gives rise to two daughter cells. Quantitative measurements of cell-cycle dynamics in single cells showed that despite variability in G1-, S-, and G2 phases, duration of mitosis is short and remarkably constant. Surprisingly, there is no correlation between cell-cycle length and mitotic duration, suggesting that mitosis is temporally insulated from variability in earlier cell-cycle phases. By combining live cell imaging and computational modeling, we showed that positive feedback is the molecular mechanism underlying the temporal insulation of mitosis. Perturbing positive feedback gave rise to a sluggish, variable entry and progression through mitosis and uncoupled duration of mitosis from variability in cell cycle length. We show that positive feedback is important to keep mitosis short, constant, and temporally insulated and anticipate it might be a commonly used regulatory strategy to create modularity in other biological systems. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Constitutive NOS uncoupling and NADPH oxidase upregulation in the penis of type 2 diabetic men with erectile dysfunction

PubMed Central

Musicki, Biljana; Burnett, Arthur L.

2016-01-01

Erectile dysfunction (ED) associated with type 2 diabetes mellitus (T2DM) involves dysfunctional nitric oxide (NO) signaling and increased oxidative stress in the penis. However, the mechanisms of endothelial NO synthase (eNOS) and neuronal NO synthase (nNOS) dysregulation, and the sources of oxidative stress, are not well defined, particularly at the human level. The objective of this study was to define whether uncoupled eNOS and nNOS, and NADPH oxidase upregulation, contribute to the pathogenesis of ED in T2DM men. Penile erectile tissue was obtained from 9 T2DM patients with ED who underwent penile prosthesis surgery for ED, and from 6 control patients without T2DM or ED who underwent penectomy for penile cancer. The dimer-to-monomer protein expression ratio, an indicator of uncoupling for both eNOS and nNOS, total protein expressions of eNOS and nNOS, as well as protein expressions of NADPH oxidase catalytic subunit gp91phox (an enzymatic source of oxidative stress) and 4-hydroxy-2-nonenal [4-HNE] and nitrotyrosine (markers of oxidative stress) were measured by Western blot in this tissue. In the erectile tissue of T2DM men, eNOS and nNOS uncoupling and protein expressions of NADPH oxidase subunit gp91phox, 4-HNE- and nitrotyrosine-modified proteins were significantly (p<0.05) increased compared to control values. Total eNOS and nNOS protein expressions were not significantly different between the groups. In conclusion, mechanisms of T2DM-associated ED in the human penis may involve uncoupled eNOS and nNOS and NADPH oxidase upregulation. Our description of molecular factors contributing to the pathogenesis of T2DM-associated ED at the human level is relevant for advancing clinically therapeutic approaches to restore erectile function in T2DM patients. PMID:28076881

Structure and dynamics of succinic, methylsuccinic and itaconic anhydrides in the gas phase

NASA Astrophysics Data System (ADS)

McMahon, Timothy J.; Bailey, Josiah R.; Bird, Ryan G.

2018-05-01

The pure rotational spectra of succinic, itaconic, and methylsuccinic anhydrides were collected in the region of 7-18 GHz using Fourier transform microwave spectroscopy. Each molecule shows varying degrees of puckering, demonstrating the effects of substitution on torsional and bond angle strain. The spectra of all three molecules exhibit perturbations consistent with internal motion; succinic and itaconic anhydride display pseudorotational motion (ΔE = 0.1 cm-1 and 0.2 cm-1, respectively), while methylsuccinic anhydride shows two uncoupled vibrations (ΔE01 = 0.4 cm-1 and ΔE02 = 1.2 cm-1). Analyses of similar five-membered rings demonstrate the relationship between the planarity of the ring and the barrier to pseudorotation.

Approach to Modeling Boundary Layer Ingestion Using a Fully Coupled Propulsion-RANS Model

NASA Technical Reports Server (NTRS)

Gray, Justin S.; Mader, Charles A.; Kenway, Gaetan K. W.; Martins, Joaquim R. R. A.

2017-01-01

Airframe-propulsion integration concepts that use boundary layer ingestion have the potential to reduce aircraft fuel burn. One concept that has been recently explored is NASA's Starc-ABL aircraft configuration, which offers the potential for 12% mission fuel burn reduction by using a turbo-electric propulsion system with an aft-mounted electrically driven boundary layer ingestion propulsor. This large potential for improved performance motivates a more detailed study of the boundary layer ingestion propulsor design, but to date, analyses of boundary layer ingestion have used uncoupled methods. These methods account for only aerodynamic effects on the propulsion system or propulsion system effects on the aerodynamics, but not both simultaneously. This work presents a new approach for building fully coupled propulsive-aerodynamic models of boundary layer ingestion propulsion systems. A 1D thermodynamic cycle analysis is coupled to a RANS simulation to model the Starc-ABL aft propulsor at a cruise condition and the effects variation in propulsor design on performance are examined. The results indicates that both propulsion and aerodynamic effects contribute equally toward the overall performance and that the fully coupled model yields substantially different results compared to uncoupled. The most significant finding is that boundary layer ingestion, while offering substantial fuel burn savings, introduces throttle dependent aerodynamics effects that need to be accounted for. This work represents a first step toward the multidisciplinary design optimization of boundary layer ingestion propulsion systems.

Monitoring Mitochondrial Electron Fluxes Using NAD(P)H-Flavoprotein Fluorometry Reveals Complex Action of Isoflurane on Cardiomyocytes

PubMed Central

Sedlic, Filip; Pravdic, Danijel; Hirata, Naoyuki; Mio, Yasushi; Sepac, Ana; Camara, Amadou K.; Wakatsuki, Tetsuro; Bosnjak, Zeljko J.; Bienengraeber, Martin

2010-01-01

Mitochondrial bioenergetic studies mostly rely on isolated mitochondria thus excluding the regulatory role of other cellular compartments important for the overall mitochondrial function. In intact cardiomyocytes, we followed the dynamics of electron fluxes along specific sites of the electron transport chain (ETC) by simultaneous detection of NAD(H)P and flavoprotein (FP) fluorescence intensities using a laser-scanning confocal microscope. This method was used to delineate the effects of isoflurane, a volatile anesthetic and cardioprotective agent, on the ETC. Comparison to the effects of well-characterized ETC inhibitors and uncoupling agent revealed two distinct effects of isoflurane: uncoupling-induced mitochondrial depolarization and inhibition of ETC at the level of complex I. In correlation, oxygen consumption measurements in cardiomyocytes confirmed a dose-dependent, dual effect of isoflurane, and in isolated mitochondria an obstruction of the ETC primarily at the level of complex I. These effects are likely responsible for the reported mild stimulation of mitochondrial reactive oxygen species (ROS) production required for the cardioprotective effects of isoflurane. In conclusion, isoflurane exhibits complex effects on the ETC in intact cardiomyocytes, altering its electron fluxes, and thereby enhancing ROS production. The NAD(P)H-FP fluorometry is a useful method for exploring the effect of drugs on mitochondria and identifying their specific sites of action within the ETC of intact cardiomyocytes. PMID:20646994

Robots Would Couple And Uncouple Fluid And Electrical Lines

NASA Technical Reports Server (NTRS)

Del Castillo, Eduardo Lopez; Davis, Virgil; Ferguson, Bob; Reichle, Garland

1992-01-01

Robots make and break connections between umbilical plates and mating connectors on rockets about to be launched. Sensing and control systems include vision, force, and torque subsystems. Enhances safety by making it possible to couple and uncouple umbilical plates quickly, without exposing human technicians to hazards of leaking fuels and oxidizers. Significantly reduces time spent to manually connect umbilicals. Robots based on similar principles used in refueling of National AeroSpace Plane (NASP) and satellites and orbital transfer vehicles in space.

Regulation of thermogenesis in plants: the interaction of alternative oxidase and plant uncoupling mitochondrial protein.

PubMed

Zhu, Yan; Lu, Jianfei; Wang, Jing; Chen, Fu; Leng, Feifan; Li, Hongyu

2011-01-01

Thermogenesis is a process of heat production in living organisms. It is rare in plants, but it does occur in some species of angiosperm. The heat is generated via plant mitochondrial respiration. As possible involvement in thermogenesis of mitochondrial factors, alternative oxidases (AOXs) and plant uncoupling mitochondrial proteins (PUMPs) have been well studied. AOXs and PUMPs are ubiquitously present in the inner membrane of plant mitochondria. They serve as two major energy dissipation systems that balance mitochondrial respiration and uncoupled phosphorylation by dissipating the H+ redox energy and proton electrochemical gradient (ΔμH+) as heat, respectively. AOXs and PUMPs exert similar physiological functions during homeothermic heat production in thermogenic plants. AOXs have five isoforms, while PUMPs have six. Both AOXs and PUMPs are encoded by small nuclear multigene families. Multiple isoforms are expressed in different tissues or organs. Extensive studies have been done in the area of thermogenesis in higher plants. In this review, we focus on the involvement and regulation of AOXs and PUMPs in thermogenesis.

Skeletal Muscle Thermogenesis and Its Role in Whole Body Energy Metabolism

PubMed Central

Herrera, Jose Luis; Reis, Felipe C. G.

2017-01-01

Obesity and diabetes has become a major epidemic across the globe. Controlling obesity has been a challenge since this would require either increased physical activity or reduced caloric intake; both are difficult to enforce. There has been renewed interest in exploiting pathways such as uncoupling protein 1 (UCP1)-mediated uncoupling in brown adipose tissue (BAT) and white adipose tissue to increase energy expenditure to control weight gain. However, relying on UCP1-based thermogenesis alone may not be sufficient to control obesity in humans. On the other hand, skeletal muscle is the largest organ and a major contributor to basal metabolic rate and increasing energy expenditure in muscle through nonshivering thermogenic mechanisms, which can substantially affect whole body metabolism and weight gain. In this review we will describe the role of Sarcolipin-mediated uncoupling of Sarcoplasmic Reticulum Calcium ATPase (SERCA) as a potential mechanism for increased energy expenditure both during cold and diet-induced thermogenesis. PMID:29086530

Uncoupling effect of palmitate is exacerbated in skeletal muscle mitochondria of sea-acclimatized king penguins (Aptenodytes patagonicus).

PubMed

Rey, Benjamin; Duchamp, Claude; Roussel, Damien

2017-09-01

In king penguin juveniles, the environmental transition from a terrestrial to a marine habitat, occurring at fledging, drastically stimulates lipid catabolism and the remodelling of muscle mitochondria to sustain extensive swimming activity and thermoregulation in the cold circumpolar oceans. However, the exact nature of these mechanisms remains only partially resolved. Here we investigated, in vitro, the uncoupling effect of increasing doses of fatty acids in pectoralis muscle intermyofibrillar mitochondria isolated, either from terrestrial never-immersed or experimentally cold water immersed pre-fledging king penguins or from sea-acclimatized fledged penguins. Mitochondria exhibited much greater palmitate-induced uncoupling respiration and higher maximal oxidative capacity after acclimatization to marine life. Such effects were not reproduced experimentally after repeated immersions in cold water, suggesting that the plasticity of mitochondrial characteristics may not be primarily driven by cold exposure per se but by other aspects of sea acclimatization. Copyright © 2017. Published by Elsevier Inc.

Mitochondrial uncouplers inhibit clathrin-mediated endocytosis largely through cytoplasmic acidification

PubMed Central

Dejonghe, Wim; Kuenen, Sabine; Mylle, Evelien; Vasileva, Mina; Keech, Olivier; Viotti, Corrado; Swerts, Jef; Fendrych, Matyáš; Ortiz-Morea, Fausto Andres; Mishev, Kiril; Delang, Simon; Scholl, Stefan; Zarza, Xavier; Heilmann, Mareike; Kourelis, Jiorgos; Kasprowicz, Jaroslaw; Nguyen, Le Son Long; Drozdzecki, Andrzej; Van Houtte, Isabelle; Szatmári, Anna-Mária; Majda, Mateusz; Baisa, Gary; Bednarek, Sebastian York; Robert, Stéphanie; Audenaert, Dominique; Testerink, Christa; Munnik, Teun; Van Damme, Daniël; Heilmann, Ingo; Schumacher, Karin; Winne, Johan; Friml, Jiří; Verstreken, Patrik; Russinova, Eugenia

2016-01-01

ATP production requires the establishment of an electrochemical proton gradient across the inner mitochondrial membrane. Mitochondrial uncouplers dissipate this proton gradient and disrupt numerous cellular processes, including vesicular trafficking, mainly through energy depletion. Here we show that Endosidin9 (ES9), a novel mitochondrial uncoupler, is a potent inhibitor of clathrin-mediated endocytosis (CME) in different systems and that ES9 induces inhibition of CME not because of its effect on cellular ATP, but rather due to its protonophore activity that leads to cytoplasm acidification. We show that the known tyrosine kinase inhibitor tyrphostinA23, which is routinely used to block CME, displays similar properties, thus questioning its use as a specific inhibitor of cargo recognition by the AP-2 adaptor complex via tyrosine motif-based endocytosis signals. Furthermore, we show that cytoplasm acidification dramatically affects the dynamics and recruitment of clathrin and associated adaptors, and leads to reduction of phosphatidylinositol 4,5-biphosphate from the plasma membrane. PMID:27271794

Mechanisms of inverse agonist action at D2 dopamine receptors

PubMed Central

Roberts, David J; Strange, Philip G

2005-01-01

Mechanisms of inverse agonist action at the D2(short) dopamine receptor have been examined. Discrimination of G-protein-coupled and -uncoupled forms of the receptor by inverse agonists was examined in competition ligand-binding studies versus the agonist [3H]NPA at a concentration labelling both G-protein-coupled and -uncoupled receptors. Competition of inverse agonists versus [3H]NPA gave data that were fitted best by a two-binding site model in the absence of GTP but by a one-binding site model in the presence of GTP. Ki values were derived from the competition data for binding of the inverse agonists to G-protein-uncoupled and -coupled receptors. Kcoupled and Kuncoupled were statistically different for the set of compounds tested (ANOVA) but the individual values were different in a post hoc test only for (+)-butaclamol. These observations were supported by simulations of these competition experiments according to the extended ternary complex model. Inverse agonist efficacy of the ligands was assessed from their ability to reduce agonist-independent [35S]GTPγS binding to varying degrees in concentration–response curves. Inverse agonism by (+)-butaclamol and spiperone occurred at higher potency when GDP was added to assays, whereas the potency of (−)-sulpiride was unaffected. These data show that some inverse agonists ((+)-butaclamol, spiperone) achieve inverse agonism by stabilising the uncoupled form of the receptor at the expense of the coupled form. For other compounds tested, we were unable to define the mechanism. PMID:15735658

eNOS uncoupling in cardiovascular diseases--the role of oxidative stress and inflammation.

PubMed

Karbach, Susanne; Wenzel, Philip; Waisman, Ari; Munzel, Thomas; Daiber, Andreas

2014-01-01

Many cardiovascular diseases and drug-induced complications are associated with - or even based on - an imbalance between the formation of reactive oxygen and nitrogen species (RONS) and antioxidant enzymes catalyzing the break-down of these harmful oxidants. According to the "kindling radical" hypothesis, the formation of RONS may trigger in certain conditions the activation of additional sources of RONS. According to recent reports, vascular dysfunction in general and cardiovascular complications such as hypertension, atherosclerosis and coronary artery diseases may be connected to inflammatory processes. The present review is focusing on the uncoupling of endothelial nitric oxide synthase (eNOS) by different mechanisms involving so-called "redox switches". The oxidative depletion of tetrahydrobiopterin (BH4), oxidative disruption of the dimeric eNOS complex, S-glutathionylation and adverse phosphorylation as well as RONS-triggered increases in levels of asymmetric dimethylarginine (ADMA) will be discussed. But also new concepts of eNOS uncoupling and state of the art detection of this process will be described. Another part of this review article will address pharmaceutical interventions preventing or reversing eNOS uncoupling and thereby normalize vascular function in a given disease setting. We finally turn our attention to the inflammatory mechanisms that are also involved in the development of endothelial dysfunction and cardiovascular disease. Inflammatory cell and cytokine profiles as well as their interactions, which are among the kindling mechanisms for the development of vascular dysfunction will be discussed on the basis of the current literature.

Photophosphorylation capacity of stable spheroplast preparations of anabaena.

PubMed

Spiller, H

1980-09-01

Spheroplasts from Anabaena 7119 (formerly designated Nostoc muscorum) were prepared in the presence of serum albumin in 0.5 molar sucrose. Electron transport and photophosphorylation were preserved (> 70% of the maximum rate for 1 week). The pH profile of electron transport and photophosphorylation in the reactions H(2)O --> NADP, H(2)O --> methyl viologen, and H(2)O --> ferricyanide shows that uncoupling by ammonia is small throughout and increases slightly with higher pH. ADP + Pi increased NADP reduction from H(2)O by 2.5-fold. The ratios of ATP formed per electron pair transported ranged from 0.9 to 1.5. Effects of catalase and superoxide dismutase on the overall O(2) balance implicate pseudocyclic electron transport and phosphorylation. The quenching of 9-aminoacridine fluorescence indicates the formation of a Delta pH from 2 to 2.6 during illumination. This pH gradient is abolished by uncouplers; however, complete uncoupling is achieved only by 3-chlorocarbonyl cyanide phenylhydrazone or valinomycin + NH(4) (+). In the presence of NH(4) (+) alone, the membrane potential may act as the driving force for photophosphorylation.Increasing amounts of bovine serum albumin protected phosphorylation from uncoupling by silicomolybdic acid. 3-(3,4-Dichlorophenyl)-1, 1-dimethylurea-insensitive water oxidation by silicomolybdic acid provides evidence that the site for 3-(3,4-dichlorophenyl)-1, 1-dimethylurea action is on the acceptor and not donor side of photosystem II in the procaryote Anabaena. It is concluded that stable spheroplasts retain coupled electron transport approaching in vivo rates.

Dissipation of the Proton Electrochemical Potential in Intact Chloroplasts (II. The pH Gradient Monitored by Cytochrome f Reduction Kinetics).

PubMed Central

Nishio, J. N.; Whitmarsh, J.

1993-01-01

The potency of various uncouplers for collapsing the light-induced pH gradient across thylakoid membranes in intact chloroplasts was investigated by time-resolved optical spectroscopy. The thylakoid transmembrane pH gradient ([delta]pH) was monitored indirectly by measuring the rate of cytochrome (Cyt) f reduction following a light flash of sufficient duration to create a sizable [delta]pH. The results show that the rate of Cyt f reduction is controlled in part by the internal pH of the thylakoid inner aqueous space. At pH values from 6.5 to 8.0, the Cyt f reduction rate was maximal, whereas at lower pH values from 6.5 to 5.5 the reduction rate decreased to 25% of the maximal rate. The ability of three uncouplers, nigericin, carbonylcyanide m-chlorophenylhydrazone, and gramicidin, to accelerate the rate of Cyt f reduction was determined for intact chloroplasts isolated from spinach (Spinacia oleracea). The efficacy of the uncouplers for collapsing the [delta]pH was determined using the empirical relationship between the [delta]pH and the Cyt f reduction rate. For intact chloroplasts, nigericin was the most effective uncoupler, followed by carbonylcyanide m-chlorophenylhydrazone, which interacted strongly with bovine serum albumin. Gramicidin D, even at high gramicidin:chlorophyll ratios, did not completely collapse the pH gradient, probably because it partitions in the envelope membranes and does not enter the intact chloroplast. PMID:12231669

Analysis of random structure-acoustic interaction problems using coupled boundary element and finite element methods

NASA Technical Reports Server (NTRS)

Mei, Chuh; Pates, Carl S., III

1994-01-01

A coupled boundary element (BEM)-finite element (FEM) approach is presented to accurately model structure-acoustic interaction systems. The boundary element method is first applied to interior, two and three-dimensional acoustic domains with complex geometry configurations. Boundary element results are very accurate when compared with limited exact solutions. Structure-interaction problems are then analyzed with the coupled FEM-BEM method, where the finite element method models the structure and the boundary element method models the interior acoustic domain. The coupled analysis is compared with exact and experimental results for a simplistic model. Composite panels are analyzed and compared with isotropic results. The coupled method is then extended for random excitation. Random excitation results are compared with uncoupled results for isotropic and composite panels.

Error analysis of multipoint flux domain decomposition methods for evolutionary diffusion problems

NASA Astrophysics Data System (ADS)

Arrarás, A.; Portero, L.; Yotov, I.

2014-01-01

We study space and time discretizations for mixed formulations of parabolic problems. The spatial approximation is based on the multipoint flux mixed finite element method, which reduces to an efficient cell-centered pressure system on general grids, including triangles, quadrilaterals, tetrahedra, and hexahedra. The time integration is performed by using a domain decomposition time-splitting technique combined with multiterm fractional step diagonally implicit Runge-Kutta methods. The resulting scheme is unconditionally stable and computationally efficient, as it reduces the global system to a collection of uncoupled subdomain problems that can be solved in parallel without the need for Schwarz-type iteration. Convergence analysis for both the semidiscrete and fully discrete schemes is presented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karabacak, Özkan, E-mail: ozkan2917@gmail.com; Department of Electronic Systems, Aalborg University, 9220 Aalborg East; Alikoç, Baran, E-mail: alikoc@itu.edu.tr

Motivated by the chaos suppression methods based on stabilizing an unstable periodic orbit, we study the stability of synchronized periodic orbits of coupled map systems when the period of the orbit is the same as the delay in the information transmission between coupled units. We show that the stability region of a synchronized periodic orbit is determined by the Floquet multiplier of the periodic orbit for the uncoupled map, the coupling constant, the smallest and the largest Laplacian eigenvalue of the adjacency matrix. We prove that the stabilization of an unstable τ-periodic orbit via coupling with delay τ is possiblemore » only when the Floquet multiplier of the orbit is negative and the connection structure is not bipartite. For a given coupling structure, it is possible to find the values of the coupling strength that stabilizes unstable periodic orbits. The most suitable connection topology for stabilization is found to be the all-to-all coupling. On the other hand, a negative coupling constant may lead to destabilization of τ-periodic orbits that are stable for the uncoupled map. We provide examples of coupled logistic maps demonstrating the stabilization and destabilization of synchronized τ-periodic orbits as well as chaos suppression via stabilization of a synchronized τ-periodic orbit.« less

C deg continuity elements by Hybrid Stress method. M.S. Thesis, 1982 Final Report

NASA Technical Reports Server (NTRS)

Kang, David Sung-Soo

1991-01-01

An intensive study of the assumed variable distribution necessary for the Assumed Displacement Formulation, the Hellinger-Reissner Formulation, and the Hu-Washizu Formulation is made in a unified manner. With emphasis on physical explanation, a systematic method for the Hybrid Stress element construction is outlined. The numerical examples use four and eight node plane stress elements and eight and twenty node solid elements. Computation cost study indicates that the hybrid stress element derived using recently developed Uncoupled Stress Formulation is comparable in CPU time to the Assumed Displacement element. Overall, main emphasis is placed on providing a broader understanding of the Hybrid Stress Formulation.

Uncoupling VOR and vestibuloautonomic retention to Coriolis acceleration training in student pilots and control subjects.

PubMed

Wang, Linjie; Cao, Yi; Tan, Cheng; Zhao, Qi; He, Siyang; Niu, Dongbin; Tang, Guohua; Zou, Peng; Xing, Lei

2017-01-01

Explore the different vestibular physiologic response retention patterns after Coriolis acceleration training in student pilots and extend the results for use with Chinese astronauts in the future. Twelve healthy control male subjects were screened from males familiar with vestibular training and who physically resembled the astronauts. Fourteen student pilots were selected from 23 participants by rotational vestibular function tests. All subjects were exposed to five-day continuous or intermittent Coriolis acceleration training. Subjective motion sickness (MS) symptom scores, electrocardiography, electrogastrography (EGG), post-rotatory nystagmus and renin-angiotensin system responses were measured before, during and after rotational vestibular function tests at different times after vestibular training. Subjects could tolerate 10 min or 15 min of vestibular with mild MS symptoms. Retention of vestibular autonomic responses (retention of MS symptom scores, heart rate variability, power density of EGG, variations in levels of arginine vasopressin) were approximately 1 week for control subjects and approximately 5 weeks for student pilots. Decreases in slow-phase velocity of post-rotatory nystagmus were maintained for 14 weeks for control subjects and 9 weeks for student pilots. Retention of the vestibulo-autonomic reaction after vestibular training was different for control subjects and student pilots. All parameters related to autonomic responses could be maintained at low levels after vestibular training for approximately 1 week for control subjects and approximately 5 weeks for student pilots. Uncoupling patterns between post-rotatory nystagmus and the vestibulo-autonomic reaction may be helpful in the design of clinical rehabilitation plans for balance-disorder patients and for exploration of artificial gravity in future space missions.

Eastern equatorial Pacific sea surface temperature annual cycle in the Kiel climate model: simulation benefits from enhancing atmospheric resolution

NASA Astrophysics Data System (ADS)

Wengel, C.; Latif, M.; Park, W.; Harlaß, J.; Bayr, T.

2018-05-01

A long-standing difficulty of climate models is to capture the annual cycle (AC) of eastern equatorial Pacific (EEP) sea surface temperature (SST). In this study, we first examine the EEP SST AC in a set of integrations of the coupled Kiel Climate Model, in which only atmosphere model resolution differs. When employing coarse horizontal and vertical atmospheric resolution, significant biases in the EEP SST AC are observed. These are reflected in an erroneous timing of the cold tongue's onset and termination as well as in an underestimation of the boreal spring warming amplitude. A large portion of these biases are linked to a wrong simulation of zonal surface winds, which can be traced back to precipitation biases on both sides of the equator and an erroneous low-level atmospheric circulation over land. Part of the SST biases also is related to shortwave radiation biases related to cloud cover biases. Both wind and cloud cover biases are inherent to the atmospheric component, as shown by companion uncoupled atmosphere model integrations forced by observed SSTs. Enhancing atmosphere model resolution, horizontal and vertical, markedly reduces zonal wind and cloud cover biases in coupled as well as uncoupled mode and generally improves simulation of the EEP SST AC. Enhanced atmospheric resolution reduces convection biases and improves simulation of surface winds over land. Analysis of a subset of models from the Coupled Model Intercomparison Project phase 5 (CMIP5) reveals that in these models, very similar mechanisms are at work in driving EEP SST AC biases.

Exercise on-transition uncoupling of ventilatory, gas exchange and cardiac hemodynamic kinetics accompany pulmonary oxygen stores depletion to impact exercise intolerance in human heart failure.

PubMed

Van Iterson, E H; Smith, J R; Olson, T P

2018-03-25

In contrast to knowledge that heart failure (HF) patients demonstrate peak exercise uncoupling across ventilation, gas exchange and cardiac haemodynamics, whether this dyssynchrony follows that at the exercise on-transition is unclear. This study tested whether exercise on-transition temporal lag for ventilation relative to gas exchange and oxygen pulse (O 2 pulse) couples with effects from abnormal pulmonary gaseous oxygen store (O 2store ) contributions to V˙O 2 to interdependently precipitate persistently elevated ventilatory demand and low oxidative metabolic capacity in HF. Beat-to-beat HR and breath-to-breath ventilation and gas exchange were continuously acquired in HF (N = 9, ejection fraction = 30 ± 9%) and matched controls (N = 10) during square-wave ergometry at 60% V˙O 2peak (46 ± 14 vs 125 ± 54-W, P < .001). Temporal responses across V˙ E , V˙O 2 and O 2 pulse were assessed for the exercise on-transition using single exponential model Phase II on-kinetic time constants (τ = time to reach 63% steady-state rise). Breath-to-breath gas fractions and respiratory flows were used to determine O 2stores . HF vs controls: τ for V˙ E (137 ± 93 vs 74 ± 40-seconds, P = .03), V˙O 2 (60 ± 40 vs 23 ± 5-seconds, P = .03) and O 2 pulse (28 ± 18 vs 23 ± 15-seconds, P = .59). Within HF, τ for V˙ E differed from O 2 pulse (P < .02), but not V˙O 2 . Exercise V˙ E rise (workload indexed) differed in HF vs controls (545 ± 139 vs 309 ± 88-mL min -1 W -1 , P < .001). Exercise on-transition O 2store depletion in HF exceeded controls, generally persisting to end-exercise. These data suggest HF demonstrated exercise on-transition O 2store depletion (high O 2store contribution to V˙O 2 ) coupled with dyssynchronous V˙ E , V˙O 2 and O 2 pulse kinetics-not attributable to prolonged cardiac haemodynamics. Persistent high ventilatory demand and low oxidative metabolic capacity in HF may be precipitated by physiological uncoupling occurring within the exercise on-transition. © 2018 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Targeting NADPH oxidase decreases oxidative stress in the transgenic sickle cell mouse penis.

PubMed

Musicki, Biljana; Liu, Tongyun; Sezen, Sena F; Burnett, Arthur L

2012-08-01

Sickle cell disease (SCD) is a state of chronic vasculopathy characterized by endothelial dysfunction and increased oxidative stress, but the sources and mechanisms responsible for reactive oxygen species (ROS) production in the penis are unknown. We evaluated whether SCD activates NADPH oxidase, induces endothelial nitric oxide synthase (eNOS) uncoupling, and decreases antioxidants in the SCD mouse penis. We further tested the hypothesis that targeting NADPH oxidase decreases oxidative stress in the SCD mouse penis. SCD transgenic (sickle) mice were used as an animal model of SCD. Hemizygous (hemi) mice served as controls. Mice received an NADPH oxidase inhibitor apocynin (10 mM in drinking water) or vehicle. Penes were excised at baseline for molecular studies. Markers of oxidative stress (4-hydroxy-2-nonenal [HNE]), sources of ROS (eNOS uncoupling and NADPH oxidase subunits p67(phox) , p47(phox) , and gp91(phox) ), and enzymatic antioxidants (superoxide dismutase [SOD]1, SOD2, catalase, and glutathione peroxidase-1 [GPx1]) were measured by Western blot in penes. Sources of ROS, oxidative stress, and enzymatic antioxidants in the SCD penis. Relative to hemi mice, SCD increased (P<0.05) protein expression of NADPH oxidase subunits p67(phox) , p47(phox) , and gp91(phox) , 4-HNE-modified proteins, induced eNOS uncoupling, and reduced Gpx1 expression in the penis. Apocynin treatment of sickle mice reversed (P<0.05) the abnormalities in protein expressions of p47(phox) , gp91(phox) (but not p67(phox) ) and 4-HNE, but only slightly (P>0.05) prevented eNOS uncoupling in the penis. Apocynin treatment of hemi mice did not affect any of these parameters. NADPH oxidase and eNOS uncoupling are sources of oxidative stress in the SCD penis; decreased GPx1 further contributes to oxidative stress. Inhibition of NADPH oxidase upregulation decreases oxidative stress, implying a major role for NADPH oxidase as a ROS source and a potential target for improving vascular function in the SCD mouse penis. © 2012 International Society for Sexual Medicine.

Small structural changes on a hydroquinone scaffold determine the complex I inhibition or uncoupling of tumoral oxidative phosphorylation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Urra, Félix A., E-mail: felix.urra@qf.uchile.cl; Córdova-Delgado, Miguel; Lapier, Michel

2016-01-15

Mitochondria participate in several distinctiveness of cancer cell, being a promising target for the design of anti-cancer compounds. Previously, we described that ortho-carbonyl hydroquinone scaffold 14 inhibits the complex I-dependent respiration with selective anti-proliferative effect on mouse mammary adenocarcinoma TA3/Ha cancer cells; however, the structural requirements of this hydroquinone scaffold to affect the oxidative phosphorylation (OXPHOS) of cancer cells have not been studied in detail. Here, we characterize the mitochondrial metabolism of TA3/Ha cancer cells, which exhibit a high oxidative metabolism, and evaluate the effect of small structural changes of the hydroquinone scaffold 14 on the respiration of this cellmore » line. Our results indicate that these structural changes modify the effect on OXPHOS, obtaining compounds with three alternative actions: inhibitors of complex I-dependent respiration, uncoupler of OXPHOS and compounds with both actions. To confirm this, the effect of a bicyclic hydroquinone (9) was evaluated in isolated mitochondria. Hydroquinone 9 increased mitochondrial respiration in state 4o without effects on the ADP-stimulated respiration (state 3{sub ADP}), decreasing the complexes I and II-dependent respiratory control ratio. The effect on mitochondrial respiration was reversed by 6-ketocholestanol addition, indicating that this hydroquinone is a protonophoric uncoupling agent. In intact TA3/Ha cells, hydroquinone 9 caused mitochondrial depolarization, decreasing intracellular ATP and NAD(P)H levels and GSH/GSSG ratio, and slightly increasing the ROS levels. Moreover, it exhibited selective NAD(P)H availability-dependent anti-proliferative effect on cancer cells. Therefore, our results indicate that the ortho-carbonyl hydroquinone scaffold offers the possibility to design compounds with specific actions on OXPHOS of cancer cells. - Highlights: • Small changes on a hydroquinone scaffold modify the action on OXPHOS of cancer cells. • Complex I Inhibitors, uncoupler of OXPHOS and agents with dual action are described. • Cpd. 9 is an uncoupler agent of OXPHOS with selective anti-proliferative effects. • Useful information to design agents with a selective mechanism on OXPHOS is provided.« less

Simulation skill of APCC set of global climate models for Asian summer monsoon rainfall variability

NASA Astrophysics Data System (ADS)

Singh, U. K.; Singh, G. P.; Singh, Vikas

2015-04-01

The performance of 11 Asia-Pacific Economic Cooperation Climate Center (APCC) global climate models (coupled and uncoupled both) in simulating the seasonal summer (June-August) monsoon rainfall variability over Asia (especially over India and East Asia) has been evaluated in detail using hind-cast data (3 months advance) generated from APCC which provides the regional climate information product services based on multi-model ensemble dynamical seasonal prediction systems. The skill of each global climate model over Asia was tested separately in detail for the period of 21 years (1983-2003), and simulated Asian summer monsoon rainfall (ASMR) has been verified using various statistical measures for Indian and East Asian land masses separately. The analysis found a large variation in spatial ASMR simulated with uncoupled model compared to coupled models (like Predictive Ocean Atmosphere Model for Australia, National Centers for Environmental Prediction and Japan Meteorological Agency). The simulated ASMR in coupled model was closer to Climate Prediction Centre Merged Analysis of Precipitation (CMAP) compared to uncoupled models although the amount of ASMR was underestimated in both models. Analysis also found a high spread in simulated ASMR among the ensemble members (suggesting that the model's performance is highly dependent on its initial conditions). The correlation analysis between sea surface temperature (SST) and ASMR shows that that the coupled models are strongly associated with ASMR compared to the uncoupled models (suggesting that air-sea interaction is well cared in coupled models). The analysis of rainfall using various statistical measures suggests that the multi-model ensemble (MME) performed better compared to individual model and also separate study indicate that Indian and East Asian land masses are more useful compared to Asia monsoon rainfall as a whole. The results of various statistical measures like skill of multi-model ensemble, large spread among the ensemble members of individual model, strong teleconnection (correlation analysis) with SST, coefficient of variation, inter-annual variability, analysis of Taylor diagram, etc. suggest that there is a need to improve coupled model instead of uncoupled model for the development of a better dynamical seasonal forecast system.

Long-chain 3-hydroxy fatty acids accumulating in long-chain 3-hydroxyacyl-CoA dehydrogenase and mitochondrial trifunctional protein deficiencies uncouple oxidative phosphorylation in heart mitochondria.

PubMed

Tonin, Anelise M; Amaral, Alexandre U; Busanello, Estela N B; Grings, Mateus; Castilho, Roger F; Wajner, Moacir

2013-02-01

Cardiomyopathy is a common clinical feature of some inherited disorders of mitochondrial fatty acid β-oxidation including mitochondrial trifunctional protein (MTP) and isolated long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiencies. Since individuals affected by these disorders present tissue accumulation of various fatty acids, including long-chain 3-hydroxy fatty acids, in the present study we investigated the effect of 3-hydroxydecanoic (3 HDCA), 3-hydroxydodecanoic (3 HDDA), 3-hydroxytetradecanoic (3 HTA) and 3-hydroxypalmitic (3 HPA) acids on mitochondrial oxidative metabolism, estimated by oximetry, NAD(P)H content, hydrogen peroxide production, membrane potential (ΔΨ) and swelling in rat heart mitochondrial preparations. We observed that 3 HTA and 3 HPA increased resting respiration and diminished the respiratory control and ADP/O ratios using glutamate/malate or succinate as substrates. Furthermore, 3 HDDA, 3 HTA and 3 HPA decreased ΔΨ, the matrix NAD(P)H pool and hydrogen peroxide production. These data indicate that these fatty acids behave as uncouplers of oxidative phosphorylation. We also verified that 3 HTA-induced uncoupling-effect was not mediated by the adenine nucleotide translocator and that this fatty acid induced the mitochondrial permeability transition pore opening in calcium-loaded organelles since cyclosporin A prevented the reduction of mitochondrial ΔΨ and swelling provoked by 3 HTA. The present data indicate that major 3-hydroxylated fatty acids accumulating in MTP and LCHAD deficiencies behave as strong uncouplers of oxidative phosphorylation potentially impairing heart energy homeostasis.

PPARδ agonist GW501516 prevents uncoupling of endothelial nitric oxide synthase in cerebral microvessels of hph-1 mice

PubMed Central

Santhanam, Anantha Vijay R.; d’Uscio, Livius V.; He, Tongrong; Katusic, Zvonimir S.

2012-01-01

Peroxisome proliferator-activated receptor delta (PPARδ) is ubiquitously expressed in the vasculature, including cerebral circulation. The role of PPARδ in metabolism of tetrahydrobiopterin (BH4) has not been studied in the cerebral microvasculature. In the present study, the effects of PPARδ agonist GW501516 on uncoupling of endothelial nitric oxide synthase (eNOS) were determined in cerebral microvessels of BH4-deficient hph-1 mice. Wild-type (B6CBA) and hph-1 mice were orally gavaged with a selective PPARδ activator, GW501516 (2 mg/kg/day) for 14 days, and thereafter, cerebral microvessels were isolated and studied. Treatment of hph-1 mice with GW501516 significantly reduced oxidation of BH4 and increased the ratio of BH4 to 7,8-BH2 (P<0.05, n=6–9). Attenuation of L-NAME-inhibitable superoxide anion levels by GW501516 demonstrated that activation of PPARδ might prevent uncoupling of endothelial nitric oxide synthase (eNOS, P<0.05, n=6–9). Western blotting studies demonstrated that GW501516 selectively increased the endothelial expressions of CuZn superoxide dismutase (P<0.05, n=6–9) and catalase (P<0.05, n=6–8). PPARδ activation increased the total nitrite and nitrate (NO2 + NO3) content in cerebral microvessels (P<0.05, n=6). Obtained results suggest that in vivo activation of PPARδ prevents eNOS uncoupling, restores bioavailability of NO and may help preserve endothelial function in the BH4-deficient cerebral circulation. PMID:22982594

PPARδ agonist GW501516 prevents uncoupling of endothelial nitric oxide synthase in cerebral microvessels of hph-1 mice.

PubMed

Santhanam, Anantha Vijay R; d'Uscio, Livius V; He, Tongrong; Katusic, Zvonimir S

2012-11-05

Peroxisome proliferator-activated receptor delta (PPARδ) is ubiquitously expressed in the vasculature, including cerebral circulation. The role of PPARδ in metabolism of tetrahydrobiopterin (BH₄) has not been studied in the cerebral microvasculature. In the present study, the effects of PPARδ agonist GW501516 on uncoupling of endothelial nitric oxide synthase (eNOS) were determined in cerebral microvessels of BH₄-deficient hph-1 mice. Wild-type (B6CBA) and hph-1 mice were orally gavaged with a selective PPARδ activator, GW501516 (2 mg/kg/day) for 14 days, and thereafter, cerebral microvessels were isolated and studied. Treatment of hph-1 mice with GW501516 significantly reduced oxidation of BH₄ and increased the ratio of BH₄ to 7,8-BH₂ (P<0.05, n=6-9). Attenuation of L-NAME-inhibitable superoxide anion levels by GW501516 demonstrated that activation of PPARδ might prevent uncoupling of endothelial nitric oxide synthase (eNOS, P<0.05, n=6-9). Western blotting studies demonstrated that GW501516 selectively increased the endothelial expressions of CuZn superoxide dismutase (P<0.05, n=6-9) and catalase (P<0.05, n=6-8). PPARδ activation increased the total nitrite and nitrate (NO₂+NO₃) content in cerebral microvessels (P<0.05, n=6). Obtained results suggest that in vivo activation of PPARδ prevents eNOS uncoupling, restores bioavailability of NO and may help preserve endothelial function in the BH₄-deficient cerebral circulation. Copyright © 2012 Elsevier B.V. All rights reserved.

Mitochondrial uncoupler exerts a synthetic lethal effect against β-catenin mutant tumor cells.

PubMed

Shikata, Yuki; Kiga, Masaki; Futamura, Yushi; Aono, Harumi; Inoue, Hiroyuki; Kawada, Manabu; Osada, Hiroyuki; Imoto, Masaya

2017-04-01

The wingless/int-1 (Wnt) signal transduction pathway plays a central role in cell proliferation, survival, differentiation and apoptosis. When β-catenin: a component of the Wnt pathway, is mutated into an active form, cell growth signaling is hyperactive and drives oncogenesis. As β-catenin is mutated in a wide variety of tumors, including up to 10% of all sporadic colon carcinomas and 20% of hepatocellular carcinomas, it has been considered a promising target for therapeutic interventions. Therefore, we screened an in-house natural product library for compounds that exhibited synthetic lethality towards β-catenin mutations and isolated nonactin, an antibiotic mitochondrial uncoupler, as a hit compound. Nonactin, as well as other mitochondrial uncouplers, induced apoptosis selectively in β-catenin mutated tumor cells. Significant tumor regression was observed in the β-catenin mutant HCT 116 xenograft model, but not in the β-catenin wild type A375 xenograft model, in response to daily administration of nonactin in vivo. Furthermore, we found that expression of an active mutant form of β-catenin induced a decrease in the glycolysis rate. Taken together, our results demonstrate that tumor cells with mutated β-catenin depend on mitochondrial oxidative phosphorylation for survival. Therefore, they undergo apoptosis in response to mitochondrial dysfunction following the addition of mitochondrial uncouplers, such as nonactin. These results suggest that targeting mitochondria is a potential chemotherapeutic strategy for tumor cells that harbor β-catenin mutations. © 2017 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

Alternative mitochondrial respiratory chains from two crustaceans: Artemia franciscana nauplii and the white shrimp, Litopenaeus vannamei.

PubMed

Rodriguez-Armenta, Chrystian; Uribe-Carvajal, Salvador; Rosas-Lemus, Monica; Chiquete-Felix, Natalia; Huerta-Ocampo, Jose Angel; Muhlia-Almazan, Adriana

2018-04-01

Mitochondrial ATP is synthesized by coupling between the electron transport chain and complex V. In contrast, physiological uncoupling of these processes allows mitochondria to consume oxygen at high rates without ATP synthesis. Such uncoupling mechanisms prevent reactive oxygen species overproduction. One of these mechanisms are the alternative redox enzymes from the mitochondrial respiratory chain, which may help cells to maintain homeostasis under stress independently of ATP synthesis. To date, no reports have been published on alternative redox enzymes in crustaceans mitochondria. Specific inhibitors were used to identify alternative redox enzymes in mitochondria isolated from Artemia franciscana nauplii, and the white shrimp, Litopenaeus vannamei. We report the presence of two alternative redox enzymes in the respiratory chain of A. franciscana nauplii, whose isolated mitochondria used glycerol-3-phosphate as a substrate, suggesting the existence of a glycerol-3-phosphate dehydrogenase. In addition, cyanide and octyl-gallate were necessary to fully inhibit this species' mitochondrial oxygen consumption, suggesting an alternative oxidase is present. The in-gel activity analysis confirmed that additional mitochondrial redox proteins exist in A. franciscana. A mitochondrial glycerol-3-phosphate dehydrogenase oxidase was identified by protein sequencing as part of a branched respiratory chain, and an alternative oxidase was also identified in this species by western blot. These results indicate different adaptive mechanisms from artemia to face environmental challenges related to the changing levels of oxygen concentration in seawater through their life cycles. No alternative redox enzymes were found in shrimp mitochondria, further efforts will determine the existence of an uncoupling mechanism such as uncoupling proteins.

Gastric electrical stimulation with short pulses reduces vomiting but not dysrhythmias in dogs.

PubMed

Chen, Jiande D Z; Qian, Liwei; Ouyang, Hui; Yin, Jieyun

2003-02-01

The aim of this study was to investigate the acute effects of 3 different methods of electrical stimulation in the prevention of vasopressin-induced emetic response and gastric dysrhythmias. Seven female hound dogs chronically implanted with 4 pairs of electrodes on gastric serosa were used in a 5-session study. Saline and vasopressin were infused in sessions 1 and 2, respectively. In the other 3 sessions with vasopressin infusion, 3 different methods of electrical stimulation (short-pulse stimulation, long-pulse stimulation, and electroacupuncture) were applied. Gastric slow waves and vomiting and behaviors suggestive of nausea were recorded in each session. In a separate study, additional experiments were performed in 5 vagotomized dogs to investigate vagally mediated mechanisms. Vasopressin induced gastric dysrhythmias, uncoupling of slow waves, and vomiting and behaviors suggestive of nausea (P < 0.02, analysis of variance). Long-pulse stimulation, but not short-pulse stimulation or electroacupuncture, was capable of preventing vasopressin-induced gastric dysrhythmias and gastric slow wave uncoupling. Short-pulse stimulation and electroacupuncture, but not long-pulse stimulation, prevented vomiting and significantly reduced the symptom scores, which was not noted in the dogs with truncal vagotomy. Long-pulse stimulation normalizes vasopressin-induced slow wave abnormalities with no improvement in vomiting and behaviors suggestive of nausea. Short-pulse stimulation and electroacupuncture prevent vomiting and behaviors suggestive of nausea induced by vasopressin but have no effects on slow waves, and their effects are vagally mediated.

Effects of mutations in the human uncoupling protein 3 gene on the respiratory quotient and fat oxidation in severe obesity and type 2 diabetes.

PubMed Central

Argyropoulos, G; Brown, A M; Willi, S M; Zhu, J; He, Y; Reitman, M; Gevao, S M; Spruill, I; Garvey, W T

1998-01-01

Human uncoupling protein 3 (UCP3) is a mitochondrial transmembrane carrier that uncouples oxidative ATP phosphorylation. With the capacity to participate in thermogenesis and energy balance, UCP3 is an important obesity candidate gene. A missense polymorphism in exon 3 (V102I) was identified in an obese and diabetic proband. A mutation introducing a stop codon in exon 4 (R143X) and a terminal polymorphism in the splice donor junction of exon 6 were also identified in a compound heterozygote that was morbidly obese and diabetic. Allele frequencies of the exon 3 and exon 6 splice junction polymorphisms were determined and found to be similar in Gullah-speaking African Americans and the Mende tribe of Sierra Leone, but absent in Caucasians. Moreover, in exon 6-splice donor heterozygotes, basal fat oxidation rates were reduced by 50%, and the respiratory quotient was markedly increased compared with wild-type individuals, implicating a role for UCP3 in metabolic fuel partitioning. PMID:9769326

Mutations in valosin-containing protein (VCP) decrease ADP/ATP translocation across the mitochondrial membrane and impair energy metabolism in human neurons

PubMed Central

Arber, Charles; Bartolome, Fernando; de Vicente, Macarena; Houlden, Henry

2017-01-01

Mutations in the gene encoding valosin-containing protein (VCP) lead to multisystem proteinopathies including frontotemporal dementia. We have previously shown that patient-derived VCP mutant fibroblasts exhibit lower mitochondrial membrane potential, uncoupled respiration, and reduced ATP levels. This study addresses the underlying basis for mitochondrial uncoupling using VCP knockdown neuroblastoma cell lines, induced pluripotent stem cells (iPSCs), and iPSC-derived cortical neurons from patients with pathogenic mutations in VCP. Using fluorescent live cell imaging and respiration analysis we demonstrate a VCP mutation/knockdown-induced dysregulation in the adenine nucleotide translocase, which results in a slower rate of ADP or ATP translocation across the mitochondrial membranes. This deregulation can explain the mitochondrial uncoupling and lower ATP levels in VCP mutation-bearing neurons via reduced ADP availability for ATP synthesis. This study provides evidence for a role of adenine nucleotide translocase in the mechanism underlying altered mitochondrial function in VCP-related degeneration, and this new insight may inform efforts to better understand and manage neurodegenerative disease and other proteinopathies. PMID:28360103

Mitochondrial Uncoupler Prodrug of 2,4-Dinitrophenol, MP201, Prevents Neuronal Damage and Preserves Vision in Experimental Optic Neuritis

PubMed Central

Khan, Reas S.; Geisler, John G.

2017-01-01

The ability of novel mitochondrial uncoupler prodrug of 2,4-dinitrophenol (DNP), MP201, to prevent neuronal damage and preserve visual function in an experimental autoimmune encephalomyelitis (EAE) model of optic neuritis was evaluated. Optic nerve inflammation, demyelination, and axonal loss are prominent features of optic neuritis, an inflammatory optic neuropathy often associated with the central nervous system demyelinating disease multiple sclerosis. Currently, optic neuritis is frequently treated with high-dose corticosteroids, but treatment fails to prevent permanent neuronal damage and associated vision changes that occur as optic neuritis resolves, thus suggesting that additional therapies are required. MP201 administered orally, once per day, attenuated visual dysfunction, preserved retinal ganglion cells (RGCs), and reduced RGC axonal loss and demyelination in the optic nerves of EAE mice, with limited effects on inflammation. The prominent mild mitochondrial uncoupling properties of MP201, with slow elimination of DNP, may contribute to the neuroprotective effect by modulating the entire mitochondria's physiology directly. Results suggest that MP201 is a potential novel treatment for optic neuritis. PMID:28680531

Vomiting and gastric electrical dysrhythmia in dogs.

PubMed

Ueno, T; Chen, J D Z

2004-04-01

The correlation between gastric myoelectrical activity (GMA) and gastrointestinal symptoms such as nausea and vomiting is poorly understood. The aim of this study was to assess the association of GMA with vomiting induced by retrograde gastric electrical stimulation or duodenal balloon distention. Ten dogs were involved in this study. Vomiting was induced by retrograde gastric electrical stimulation in 6 dogs and by duodenal balloon distention in 4 dogs. Computerized spectral analysis and visual analysis were applied to detect the GMA change during various periods before and after vomiting. Gastric dysrhythmia preceded vomiting but was of brief duration. The major pattern of dysrhythmia immediately before vomiting was tachyarrhythmia and gastric slow wave was completely uncoupled before vomiting. Gastric dysrhythmia and slow wave uncoupling were also noticed immediately after vomiting but the dogs recovered quickly. The major pattern of dysrhythmia after vomiting was arrhythmia. GMA was normal during the periods other than 5 min before and during vomiting and 5 min after vomiting. Gastric dysrhythmia seems to be the cause of vomiting induced by retrograde gastric electrical stimulation or duodenal balloon distention. It is brief and characterized with tachyarrhythmia and uncoupling.

Arginase-I enhances vascular endothelial inflammation and senescence through eNOS-uncoupling.

PubMed

Zhu, Cuicui; Yu, Yi; Montani, Jean-Pierre; Ming, Xiu-Fen; Yang, Zhihong

2017-02-02

Augmented arginase-II (Arg-II) is implicated in endothelial senescence and inflammation through a mutual positive regulatory circuit with S6K1. This study was conducted to investigate whether Arg-I, another isoform of arginase that has been also reported to play a role in vascular endothelial dysfunction, promotes endothelial senescence through similar mechanisms. The non-senescent human endothelial cells from umbilical veins (passage 2 to 4) were transduced with empty recombinant adenovirus vector (rAd/CMV) as control or rAd/CMV-Arg-I to overexpress Arg-I. Overexpressing Arg-I promoted eNOS-uncoupling, enhanced senescence markers including p53-S15, p21 and senescence-associated β-galactosidase (SA-β-gal) staining, and increased inflammatory vascular adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) as well as monocyte adhesion to endothelial cells without activating S6K1. All the effects of Arg-I were inhibited by the anti-oxidant N-acetylcysteine (NAC). Our study demonstrates that Arg-I promotes endothelial senescence and inflammatory responses through eNOS-uncoupling unrelated to activation of the S6K1 pathway.

UCP2 and 3 deletion screening and distribution in 15 pig breeds.

PubMed

Li, Yanhua; Li, Hanjie; Zhao, Xingbo; Li, Ning; Wu, Changxin

2007-02-01

The uncoupling protein family is a mitochondrial anion carrier family. It plays an important role in the biological traits of animal body weight, basal metabolic rate and energy conversion. Using PCR and PCR-SSCP, we scanned the porcine uncoupling protein 2 gene (UCP2) and uncoupling protein 3 gene (UCP3) and found seven deletion sites, three in UCP2 and four in UCP3. The deletions in 15 pig breeds showed that deletion influenced weight. The genotype compounding of seven deletion sites in 15 pig breeds had significant effects on performance traits of the pig, such as body weight. We predicted the potential protein factor binding sites using the transcription factor analysis tool TFSearch version 1.3 online. Two deletions (1830 nt and 3219 nt) in UCP3 were found to change the transcriptional factor sites. The 16 bp deletion in 1830 nt added a SP1 site and a 6 bp deletion in 3219 nt removed two MZF1 sites. Seven deletion polymorphisms were covered in introns of linkage genes of UCP2 and UCP3, showing that UCPs have conservation and genetic reliability.

Catenin-dependent cadherin function drives divisional segregation of spinal motor neurons.

PubMed

Bello, Sanusi M; Millo, Hadas; Rajebhosale, Manisha; Price, Stephen R

2012-01-11

Motor neurons that control limb movements are organized as a neuronal nucleus in the developing ventral horn of the spinal cord called the lateral motor column. Neuronal migration segregates motor neurons into distinct lateral and medial divisions within the lateral motor column that project axons to dorsal or ventral limb targets, respectively. This migratory phase is followed by an aggregation phase whereby motor neurons within a division that project to the same muscle cluster together. These later phases of motor neuron organization depend on limb-regulated differential cadherin expression within motor neurons. Initially, all motor neurons display the same cadherin expression profile, which coincides with the migratory phase of motor neuron segregation. Here, we show that this early, pan-motor neuron cadherin function drives the divisional segregation of spinal motor neurons in the chicken embryo by controlling motor neuron migration. We manipulated pan-motor neuron cadherin function through dissociation of cadherin binding to their intracellular partners. We found that of the major intracellular transducers of cadherin signaling, γ-catenin and α-catenin predominate in the lateral motor column. In vivo manipulations that uncouple cadherin-catenin binding disrupt divisional segregation via deficits in motor neuron migration. Additionally, reduction of the expression of cadherin-7, a cadherin predominantly expressed in motor neurons only during their migration, also perturbs divisional segregation. Our results show that γ-catenin-dependent cadherin function is required for spinal motor neuron migration and divisional segregation and suggest a prolonged role for cadherin expression in all phases of motor neuron organization.

Sustainability of a Compartmentalized Host-Parasite Replicator System under Periodic Washout-Mixing Cycles

PubMed Central

Furubayashi, Taro

2018-01-01

The emergence and dominance of parasitic replicators are among the major hurdles for the proliferation of primitive replicators. Compartmentalization of replicators is proposed to relieve the parasite dominance; however, it remains unclear under what conditions simple compartmentalization uncoupled with internal reaction secures the long-term survival of a population of primitive replicators against incessant parasite emergence. Here, we investigate the sustainability of a compartmentalized host-parasite replicator (CHPR) system undergoing periodic washout-mixing cycles, by constructing a mathematical model and performing extensive simulations. We describe sustainable landscapes of the CHPR system in the parameter space and elucidate the mechanism of phase transitions between sustainable and extinct regions. Our findings revealed that a large population size of compartments, a high mixing intensity, and a modest amount of nutrients are important factors for the robust survival of replicators. We also found two distinctive sustainable phases with different mixing intensities. These results suggest that a population of simple host–parasite replicators assumed before the origin of life can be sustained by a simple compartmentalization with periodic washout-mixing processes. PMID:29373536

Molecular properties of muscarinic acetylcholine receptors

PubMed Central

HAGA, Tatsuya

2013-01-01

Muscarinic acetylcholine receptors, which comprise five subtypes (M1-M5 receptors), are expressed in both the CNS and PNS (particularly the target organs of parasympathetic neurons). M1-M5 receptors are integral membrane proteins with seven transmembrane segments, bind with acetylcholine (ACh) in the extracellular phase, and thereafter interact with and activate GTP-binding regulatory proteins (G proteins) in the intracellular phase: M1, M3, and M5 receptors interact with Gq-type G proteins, and M2 and M4 receptors with Gi/Go-type G proteins. Activated G proteins initiate a number of intracellular signal transduction systems. Agonist-bound muscarinic receptors are phosphorylated by G protein-coupled receptor kinases, which initiate their desensitization through uncoupling from G proteins, receptor internalization, and receptor breakdown (down regulation). Recently the crystal structures of M2 and M3 receptors were determined and are expected to contribute to the development of drugs targeted to muscarinic receptors. This paper summarizes the molecular properties of muscarinic receptors with reference to the historical background and bias to studies performed in our laboratories. PMID:23759942

Ethylene Glycol Quenching of Nitrogenase Catalysis: An Electron Paramagnetic Resonance Spectroscopic Study of Nitrogenase Turnover States and CO Bonding.

PubMed

Hales, Brian J

2015-07-14

Most hydrophilic organic solvents inhibit enzymatic activity. Nitrogenase is shown to be approximately 3 times more sensitive to organic inhibition than most other soluble enzymes. Ethylene glycol (EG) is demonstrated to rapidly inhibit nitrogenase activity without uncoupling ATP hydrolysis. Our data suggest the mechanism of inhibition is EG's blocking of binding of MgATP to the nitrogenase Fe protein. EG quenching allows, for the first time, the observation of the relaxation of the intermediate reaction states at room temperature. Electron paramagnetic resonance (EPR) spectroscopy is used to monitor the room-temperature decay of the nitrogenase turnover states following EG quenching of catalytic activity. The return of the intermediate states to the resting state occurs in multiple phases over 2 h. During the initial stage, nitrogenase still possesses the ability to generate CO-induced EPR signals even though catalytic activity has ceased. During the last phase of relaxation, the one-electron reduced state of the MoFe protein (E1) relaxes to the resting state (E0) in a slow first-order reaction.

Short-term regulation and alternative pathways of photosynthetic electron transport in Hibiscus rosa-sinensis leaves.

PubMed

Trubitsin, Boris V; Vershubskii, Alexey V; Priklonskii, Vladimir I; Tikhonov, Alexander N

2015-11-01

In this work, using the EPR and PAM-fluorometry methods, we have studied induction events of photosynthetic electron transport in Hibiscus rosa-sinensis leaves. The methods used are complementary, providing efficient tools for in situ monitoring of P700 redox transients and photochemical activity of photosystem II (PSII). The induction of P700(+) in dark-adapted leaves is characterized by the multiphase kinetics with a lag-phase, which duration elongates with the dark-adaptation time. Analyzing effects of the uncoupler monensin and artificial electron carrier methylviologen (MV) on photooxidation of P700 and slow induction of chlorophyll a fluorescence (SIF), we could ascribe different phases of transient kinetics of electron transport processes in dark-adapted leaves to the following regulatory mechanisms: (i) acceleration of electron transfer on the acceptor side of PSI, (ii) pH-dependent modulation of the intersystem electron flow, and (iii) re-distribution of electron fluxes between alternative (linear, cyclic, and pseudocyclic) pathways. Monensin significantly decreases a level of P700(+) and inhibits SIF. MV, which mediates electron flow from PSI to O2 with consequent formation of H2O2, promotes a rapid photooxidation of P700 without any lag-phase peculiar to untreated leaves. MV-mediated water-water cycle (H2O→PSII→PSI→MV→O2→H2O2→H2O) is accompanied by generation of ascorbate free radicals. This suggests that the ascorbate peroxidase system of defense against reactive oxygen species is active in chloroplasts of H. rosa-sinensis leaves. In DCMU-treated chloroplasts with inhibited PSII, the contribution of cyclic electron flow is insignificant as compared to linear electron flow. For analysis of induction events, we have simulated electron transport processes within the framework of our generalized mathematical model of oxygenic photosynthesis, which takes into account pH-dependent mechanisms of electron transport control and re-distribution of electron fluxes between alternative pathways. The model adequately describes the main peculiarities of P700(+) induction and dynamics of the intersystem electron transport. Copyright © 2015 Elsevier B.V. All rights reserved.

Implications of mitochondrial uncoupling in skeletal muscle in the development and treatment of obesity.

PubMed

Thrush, A Brianne; Dent, Robert; McPherson, Ruth; Harper, Mary-Ellen

2013-10-01

Understanding the metabolic factors that contribute to obesity development and weight loss success are critical for combating obesity and obesity-related disorders. This review provides an overview of energy metabolism with a particular focus on mitochondrial function in health and in obesity. Mitochondrial proton leak contributes significantly to whole body energy expenditure and the potential role of energy uncoupling in weight loss success is discussed. We provide evidence to support the hypothesis that differences in energy efficiency are important regulators of body weight and weight loss success. © 2013 FEBS.

Optimal parameters uncoupling vibration modes of oscillators

NASA Astrophysics Data System (ADS)

Le, K. C.; Pieper, A.

2017-07-01

This paper proposes a novel optimization concept for an oscillator with two degrees of freedom. By using specially defined motion ratios, we control the action of springs to each degree of freedom of the oscillator. We aim at showing that, if the potential action of the springs in one period of vibration, used as the payoff function for the conservative oscillator, is maximized among all admissible parameters and motions satisfying Lagrange's equations, then the optimal motion ratios uncouple vibration modes. A similar result holds true for the dissipative oscillator having dampers. The application to optimal design of vehicle suspension is discussed.

Electrodiffusion: a continuum modeling framework for biomolecular systems with realistic spatiotemporal resolution.

PubMed

Lu, Benzhuo; Zhou, Y C; Huber, Gary A; Bond, Stephen D; Holst, Michael J; McCammon, J Andrew

2007-10-07

A computational framework is presented for the continuum modeling of cellular biomolecular diffusion influenced by electrostatic driving forces. This framework is developed from a combination of state-of-the-art numerical methods, geometric meshing, and computer visualization tools. In particular, a hybrid of (adaptive) finite element and boundary element methods is adopted to solve the Smoluchowski equation (SE), the Poisson equation (PE), and the Poisson-Nernst-Planck equation (PNPE) in order to describe electrodiffusion processes. The finite element method is used because of its flexibility in modeling irregular geometries and complex boundary conditions. The boundary element method is used due to the convenience of treating the singularities in the source charge distribution and its accurate solution to electrostatic problems on molecular boundaries. Nonsteady-state diffusion can be studied using this framework, with the electric field computed using the densities of charged small molecules and mobile ions in the solvent. A solution for mesh generation for biomolecular systems is supplied, which is an essential component for the finite element and boundary element computations. The uncoupled Smoluchowski equation and Poisson-Boltzmann equation are considered as special cases of the PNPE in the numerical algorithm, and therefore can be solved in this framework as well. Two types of computations are reported in the results: stationary PNPE and time-dependent SE or Nernst-Planck equations solutions. A biological application of the first type is the ionic density distribution around a fragment of DNA determined by the equilibrium PNPE. The stationary PNPE with nonzero flux is also studied for a simple model system, and leads to an observation that the interference on electrostatic field of the substrate charges strongly affects the reaction rate coefficient. The second is a time-dependent diffusion process: the consumption of the neurotransmitter acetylcholine by acetylcholinesterase, determined by the SE and a single uncoupled solution of the Poisson-Boltzmann equation. The electrostatic effects, counterion compensation, spatiotemporal distribution, and diffusion-controlled reaction kinetics are analyzed and different methods are compared.

A study of the Tyrone-Mount Union lineament by remote sensing techniques and field methods

NASA Technical Reports Server (NTRS)

Gold, D. P. (Principal Investigator)

1977-01-01

The author has identified the following significant results. This study has shown that subtle variations in fold axes, fold form, and stratigraphic thickness can be delineated. Many of the conclusions were based on extrapolation in similitude to different scales. A conceptual model was derived for the Tyrone-Mount Union lineament. In this model, the lineament the morphological expression of a zone of fracture concentrations which penetrated basement rocks and may have acted as a curtain to regional stresses or as a domain boundary between uncoupled adjacent crustal blocks.

Two controller design approaches for decentralized systems

NASA Technical Reports Server (NTRS)

Ozguner, U.; Khorrami, F.; Iftar, A.

1988-01-01

Two different philosophies for designing the controllers of decentralized systems are considered within a quadratic regulator framework which is generalized to admit decentralized frequency weighting. In the first approach, the total system model is examined, and the feedback strategy for each channel or subsystem is determined. In the second approach, separate, possibly overlapping, and uncoupled models are analyzed for each channel, and the results can be combined to study the original system. The two methods are applied to the example of a model of the NASA COFS Mast Flight System.

Recovery from the DNA Replication Checkpoint

PubMed Central

Chaudhury, Indrajit; Koepp, Deanna M.

2016-01-01

Checkpoint recovery is integral to a successful checkpoint response. Checkpoint pathways monitor progress during cell division so that in the event of an error, the checkpoint is activated to block the cell cycle and activate repair pathways. Intrinsic to this process is that once repair has been achieved, the checkpoint signaling pathway is inactivated and cell cycle progression resumes. We use the term “checkpoint recovery” to describe the pathways responsible for the inactivation of checkpoint signaling and cell cycle re-entry after the initial stress has been alleviated. The DNA replication or S-phase checkpoint monitors the integrity of DNA synthesis. When replication stress is encountered, replication forks are stalled, and the checkpoint signaling pathway is activated. Central to recovery from the S-phase checkpoint is the restart of stalled replication forks. If checkpoint recovery fails, stalled forks may become unstable and lead to DNA breaks or unusual DNA structures that are difficult to resolve, causing genomic instability. Alternatively, if cell cycle resumption mechanisms become uncoupled from checkpoint inactivation, cells with under-replicated DNA might proceed through the cell cycle, also diminishing genomic stability. In this review, we discuss the molecular mechanisms that contribute to inactivation of the S-phase checkpoint signaling pathway and the restart of replication forks during recovery from replication stress. PMID:27801838

Microbial and sponge loops modify fish production in phase-shifting coral reefs.

PubMed

Silveira, Cynthia B; Silva-Lima, Arthur W; Francini-Filho, Ronaldo B; Marques, Jomar S M; Almeida, Marcelo G; Thompson, Cristiane C; Rezende, Carlos E; Paranhos, Rodolfo; Moura, Rodrigo L; Salomon, Paulo S; Thompson, Fabiano L

2015-10-01

Shifts from coral to algae dominance of corals reefs have been correlated to fish biomass loss and increased microbial metabolism. Here we investigated reef benthic and planktonic primary production, benthic dissolved organic carbon (DOC) release and bacterial growth efficiency in the Abrolhos Bank, South Atlantic. Benthic DOC release rates are higher while water column bacterial growth efficiency is lower at impacted reefs. A trophic model based on the benthic and planktonic primary production was able to predict the observed relative fish biomass in healthy reefs. In contrast, in impacted reefs, the observed omnivorous fish biomass is higher, while that of the herbivorous/coralivorous fish is lower than predicted by the primary production-based model. Incorporating recycling of benthic-derived carbon in the model through microbial and sponge loops explains the difference and predicts the relative fish biomass in both reef types. Increased benthic carbon release rates and bacterial carbon metabolism, but decreased bacterial growth efficiency could lead to carbon losses through respiration and account for the uncoupling of benthic and fish production in phase-shifting reefs. Carbon recycling by microbial and sponge loops seems to promote an increase of small-bodied fish productivity in phase-shifting coral reefs. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Mechanism for the uncoupling of oxidative phosphorylation by juliprosopine on rat brain mitochondria.

PubMed

Maioli, Marcos A; Lemos, Danilo E C V; Guelfi, Marieli; Medeiros, Hyllana C D; Riet-Correa, Franklin; Medeiros, Rosane M T; Barbosa-Filho, José M; Mingatto, Fábio E

2012-12-15

Prosopis juliflora, popularly known as Algaroba, is a major problem because the lack of food during the driest times of the year and its high palatability and nutritional value make its fruits (pods) much appreciated by cattle, goats, sheep and other animals. However, the consumption of this plant for long periods can cause a disease called cara-torta (pie face), which is characterized by cranial nerve dysfunction, mainly due to the degeneration and disappearance of neurons in the trigeminal motor nucleus. Algaroba contains piperidine alkaloids that have been suggested as being responsible for its toxicity; one of these alkaloids is juliprosopine. This study was conducted to evaluate the mechanisms of action of juliprosopine in isolated rat brain mitochondria to evaluate the potential mechanisms that lead to neurotoxicity in animals intoxicated by algaroba. Juliprosopine stimulated state-4 respiration at concentrations of 10-25 μM, affected the membrane potential at all concentrations studied (5-25 μM) and affected ATP production only at higher concentrations (15 and 25 μM). Juliprosopine cannot be classified as a member of the protonophoric class of uncouplers, such as 2,4-dinitrophenol or CCCP (m-chlorophenylhydrazone), due to its inability to promote mitochondrial swelling in the hyposmotic medium of potassium acetate. In addition, carboxyatractyloside, Mg(2+), cyclosporine A and dithiothreitol did not protect the uncoupling induced by juliprosopine. Because juliprosopine increased the fluorescence responses of mitochondria labeled with 1-aniline-8-naphthalene sulfonate (ANS) and DPH (1,6-diphenyl-1,3,5-hexatriene), we suggested that its uncoupling action must be attributed to a modification of the arrangement of the inner mitochondrial membrane. Copyright © 2012 Elsevier Ltd. All rights reserved.

Differential effects of eNOS uncoupling on conduit and small arteries in GTP-cyclohydrolase I-deficient hph-1 mice.

PubMed

d'Uscio, Livius V; Smith, Leslie A; Katusic, Zvonimir S

2011-12-01

In the present study, we used the hph-1 mouse, which displays GTP-cyclohydrolase I (GTPCH I) deficiency, to test the hypothesis that loss of tetrahydrobiopterin (BH(4)) in conduit and small arteries activates compensatory mechanisms designed to protect vascular wall from oxidative stress induced by uncoupling of endothelial nitric oxide synthase (eNOS). Both GTPCH I activity and BH(4) levels were reduced in the aortas and small mesenteric arteries of hph-1 mice. However, the BH(4)-to-7,8-dihydrobiopterin ratio was significantly reduced only in hph-1 aortas. Furthermore, superoxide anion and 3-nitrotyrosine production were significantly enhanced in aortas but not in small mesenteric arteries of hph-1 mice. In contrast to the aorta, protein expression of copper- and zinc-containing superoxide dismutase (CuZnSOD) was significantly increased in small mesenteric arteries of hph-1 mice. Protein expression of catalase was increased in both aortas and small mesenteric arteries of hph-1 mice. Further analysis of endothelial nitric oxide synthase (eNOS)/cyclic guanosine monophosphate (cGMP) signaling demonstrated that protein expression of phosphorylated Ser(1177)-eNOS as well as basal cGMP levels and hydrogen peroxide was increased in hph-1 aortas. Increased production of hydrogen peroxide in hph-1 mice aortas appears to be the most likely mechanism responsible for phosphorylation of eNOS and elevation of cGMP. In contrast, upregulation of CuZnSOD and catalase in resistance arteries is sufficient to protect vascular tissue from increased production of reactive oxygen species generated by uncoupling of eNOS. The results of our study suggest that anatomical origin determines the ability of vessel wall to cope with oxidative stress induced by uncoupling of eNOS.

Pentachlorophenol hydroxylase, a poorly functioning enzyme required for degradation of pentachlorophenol by Sphingobium chlorophenolicum

PubMed Central

Hlouchova, Klara; Rudolph, Johannes; Pietari, Jaana M.H.; Behlen, Linda S.; Copley, Shelley D.

2014-01-01

Several strains of Sphingobium chlorophenolicum have been isolated from soil that was heavily contaminated with pentachlorophenol (PCP), a toxic pesticide introduced in the 1930s. S. chlorophenolicum appears to have assembled a poorly functioning pathway for degradation of PCP by patching enzymes recruited via two independent horizontal gene transfer events into an existing metabolic pathway. Flux through the pathway is limited by PCP hydroxylase. PCP hydroxylase is a dimeric protein that belongs to the family of flavin-dependent phenol hydroxylases. In the presence of NADPH, PCP hydroxylase converts PCP to tetrachlorobenzoquinone (TCBQ). The kcat for PCP (0.024 s−1) is very low, suggesting that the enzyme is not well evolved for turnover of this substrate. Structure/activity studies reveal that substrate binding and activity are enhanced by a low pKa for the phenolic proton, increased hydrophobicity, and the presence of a substituent ortho to the hydroxyl group of the phenol. PCP hydroxylase exhibits substantial uncoupling; the C4a-hydroxyflavin intermediate, instead of hydroxylating the substrate, can decompose to produce H2O2 in a futile cycle that consumes NADPH. The extent of uncoupling varies from 0 – 100% with different substrates. Uncoupling is increased by the presence of bulky substituents in the 3-, 4-, or 5-position, and lessened by the presence of a chlorine in the ortho position. The effectiveness of PCP hydroxylase is additionally hindered by its promiscuous activity with TCHQ, a downstream metabolite in the degradation pathway. The conversion of TCHQ to TCBQ reverses flux through the pathway. Substantial uncoupling also occurs during the reaction with TCHQ. PMID:22482720

Constitutive Uncoupling of Pathways of Gene Expression That Control Growth and Differentiation in Myeloid Leukemia: A Model for the Origin and Progression of Malignancy

NASA Astrophysics Data System (ADS)

Sachs, Leo

1980-10-01

Chemical carcinogens and tumor promoters have pleiotropic effects. Tumor initiators can produce a variety of mutations and tumor promoters can regulate a variety of physiological molecules that control growth and differentiation. The appropriate mutation and the regulation of the appropriate molecules to induce cell growth can initiate and promote the sequence of changes required for transformation of normal cells into malignant cells. After this sequence of changes, some tumors can still be induced to revert with a high frequency from a malignant phenotype to a nonmalignant phenotype. Results obtained from analysis of regulation of growth and differentiation in normal and leukemic myeloid cells, the phenotypic reversion of malignancy by induction of normal differentiation in myeloid leukemia, and the blocks in differentiation-defective leukemic cell mutants have been used to propose a general model for the origin and progression of malignancy. The model states that malignancy originates by changing specific pathways of gene expression required for growth from inducible to constitutive in cells that can still be induced to differentiate normally by the physiological inducer of differentiation. The malignant cells, unlike the normal cells, then no longer require the physiological inducer for growth. This changes the requirements for growth and uncouples growth from differentiation. Constitutive expression of other specific pathways can uncouple other controls, which then causes blocks in differentiation and the further progression of malignancy. The existence of specific constitutive pathways of gene expression that uncouple controls in malignant cells can also explain the expression of fetal proteins, hormones, and some other specialized products of normal development in various types of tumors.

Mode shift of the voltage sensors in Shaker K+ channels is caused by energetic coupling to the pore domain

PubMed Central

Haddad, Georges A.

2011-01-01

The voltage sensors of voltage-gated ion channels undergo a conformational change upon depolarization of the membrane that leads to pore opening. This conformational change can be measured as gating currents and is thought to be transferred to the pore domain via an annealing of the covalent link between voltage sensor and pore (S4-S5 linker) and the C terminus of the pore domain (S6). Upon prolonged depolarizations, the voltage dependence of the charge movement shifts to more hyperpolarized potentials. This mode shift had been linked to C-type inactivation but has recently been suggested to be caused by a relaxation of the voltage sensor itself. In this study, we identified two ShakerIR mutations in the S4-S5 linker (I384N) and S6 (F484G) that, when mutated, completely uncouple voltage sensor movement from pore opening. Using these mutants, we show that the pore transfers energy onto the voltage sensor and that uncoupling the pore from the voltage sensor leads the voltage sensors to be activated at more negative potentials. This uncoupling also eliminates the mode shift occurring during prolonged depolarizations, indicating that the pore influences entry into the mode shift. Using voltage-clamp fluorometry, we identified that the slow conformational change of the S4 previously correlated with the mode shift disappears when uncoupling the pore. The effects can be explained by a mechanical load that is imposed upon the voltage sensors by the pore domain and allosterically modulates its conformation. Mode shift is caused by the stabilization of the open state but leads to a conformational change in the voltage sensor. PMID:21518834

pH-dependent modulation of connexin-based gap junctional uncouplers

PubMed Central

Skeberdis, Vytenis A; Rimkute, Lina; Skeberdyte, Aiste; Paulauskas, Nerijus; Bukauskas, Feliksas F

2011-01-01

Abstract Gap junction (GJ) channels formed from connexin (Cx) proteins provide a direct pathway for electrical and metabolic cell–cell communication exhibiting high sensitivity to intracellular pH (pHi). We examined pHi-dependent modulation of junctional conductance (gj) of GJs formed of Cx26, mCx30.2, Cx36, Cx40, Cx43, Cx45, Cx46, Cx47 and Cx50 by reagents representing several distinct groups of uncouplers, such as long carbon chain alkanols (LCCAs), arachidonic acid, carbenoxolone, isoflurane, flufenamic acid and mefloquine. We demonstrate that alkalization by NH4Cl to pH ∼8 increased gj in cells expressing mCx30.2 and Cx45, yet did not affect gj of Cx26, Cx40, Cx46, Cx47 and Cx50 and decreased it in Cx43 and Cx36 GJs. Unexpectedly, cells expressing Cx45, but not other Cxs, exhibited full coupling recovery after alkalization with NH4Cl under the continuous presence of LCCAs, isoflurane and mefloquine. There was no coupling recovery by alkalization in the presence of arachidonic acid, carbenoxolone and flufenamic acid. In cells expressing Cx45, IC50 for octanol was 0.1, 0.25 and 2.68 mm at pHi values of 6.9, 7.2 and 8.1, respectively. Histidine modification of Cx45 protein by N-bromosuccinimide reduced the coupling-promoting effect of NH4Cl as well as the uncoupling effect of octanol. This suggests that LCCAs and some other uncouplers may act through the formation of hydrogen bonds with the as-of-yet unidentified histidine/s of the Cx45 GJ channel protein. PMID:21606109

Implications of neurovascular uncoupling in functional magnetic resonance imaging (fMRI) of brain tumors.

PubMed

Pak, Rebecca W; Hadjiabadi, Darian H; Senarathna, Janaka; Agarwal, Shruti; Thakor, Nitish V; Pillai, Jay J; Pathak, Arvind P

2017-11-01

Functional magnetic resonance imaging (fMRI) serves as a critical tool for presurgical mapping of eloquent cortex and changes in neurological function in patients diagnosed with brain tumors. However, the blood-oxygen-level-dependent (BOLD) contrast mechanism underlying fMRI assumes that neurovascular coupling remains intact during brain tumor progression, and that measured changes in cerebral blood flow (CBF) are correlated with neuronal function. Recent preclinical and clinical studies have demonstrated that even low-grade brain tumors can exhibit neurovascular uncoupling (NVU), which can confound interpretation of fMRI data. Therefore, to avoid neurosurgical complications, it is crucial to understand the biophysical basis of NVU and its impact on fMRI. Here we review the physiology of the neurovascular unit, how it is remodeled, and functionally altered by brain cancer cells. We first discuss the latest findings about the components of the neurovascular unit. Next, we synthesize results from preclinical and clinical studies to illustrate how brain tumor induced NVU affects fMRI data interpretation. We examine advances in functional imaging methods that permit the clinical evaluation of brain tumors with NVU. Finally, we discuss how the suppression of anomalous tumor blood vessel formation with antiangiogenic therapies can "normalize" the brain tumor vasculature, and potentially restore neurovascular coupling.

Matrix-Assisted Transplantation of Functional Beige Adipose Tissue

PubMed Central

Tharp, Kevin M.; Jha, Amit K.; Kraiczy, Judith; Yesian, Alexandra; Karateev, Grigory; Sinisi, Riccardo; Dubikovskaya, Elena A.

2015-01-01

Novel, clinically relevant, approaches to shift energy balance are urgently needed to combat metabolic disorders such as obesity and diabetes. One promising approach has been the expansion of brown adipose tissues that express uncoupling protein (UCP) 1 and thus can uncouple mitochondrial respiration from ATP synthesis. While expansion of UCP1-expressing adipose depots may be achieved in rodents via genetic and pharmacological manipulations or the transplantation of brown fat depots, these methods are difficult to use for human clinical intervention. We present a novel cell scaffold technology optimized to establish functional brown fat–like depots in vivo. We adapted the biophysical properties of hyaluronic acid–based hydrogels to support the differentiation of white adipose tissue–derived multipotent stem cells (ADMSCs) into lipid-accumulating, UCP1-expressing beige adipose tissue. Subcutaneous implantation of ADMSCs within optimized hydrogels resulted in the establishment of distinct UCP1-expressing implants that successfully attracted host vasculature and persisted for several weeks. Importantly, implant recipients demonstrated elevated core body temperature during cold challenges, enhanced respiration rates, improved glucose homeostasis, and reduced weight gain, demonstrating the therapeutic merit of this highly translatable approach. This novel approach is the first truly clinically translatable system to unlock the therapeutic potential of brown fat–like tissue expansion. PMID:26293504

Calculation of linearized supersonic flow over slender cones of arbitrary cross section

NASA Technical Reports Server (NTRS)

Mascitti, V. R.

1972-01-01

Supersonic linearized conical-flow theory is used to determine the flow over slender pointed cones having horizontal and vertical planes of symmetry. The geometry of the cone cross sections and surface velocities are expanded in Fourier series. The symmetry condition permits the uncoupling of lifting and nonlifting solutions. The present method reduces to Ward's theory for flow over a cone of elliptic cross section. Results are also presented for other shapes. Results by this method diverge for cross-sectional shapes where the maximum thickness is large compared with the minimum thickness. However, even for these slender-body shapes, lower order solutions are good approximations to the complete solution.

Simulations of 6-DOF Motion with a Cartesian Method

NASA Technical Reports Server (NTRS)

Murman, Scott M.; Aftosmis, Michael J.; Berger, Marsha J.; Kwak, Dochan (Technical Monitor)

2003-01-01

Coupled 6-DOF/CFD trajectory predictions using an automated Cartesian method are demonstrated by simulating a GBU-32/JDAM store separating from an F-18C aircraft. Numerical simulations are performed at two Mach numbers near the sonic speed, and compared with flight-test telemetry and photographic-derived data. Simulation results obtained with a sequential-static series of flow solutions are contrasted with results using a time-dependent flow solver. Both numerical methods show good agreement with the flight-test data through the first half of the simulations. The sequential-static and time-dependent methods diverge over the last half of the trajectory prediction. after the store produces peak angular rates. A cost comparison for the Cartesian method is included, in terms of absolute cost and relative to computing uncoupled 6-DOF trajectories. A detailed description of the 6-DOF method, as well as a verification of its accuracy, is provided in an appendix.

Coordination of FocA and Pyruvate Formate-Lyase Synthesis in Escherichia coli Demonstrates Preferential Translocation of Formate over Other Mixed-Acid Fermentation Products

PubMed Central

Beyer, Lydia; Doberenz, Claudia; Falke, Dörte; Hunger, Doreen; Suppmann, Bernhard

2013-01-01

Enterobacteria such as Escherichia coli generate formate, lactate, acetate, and succinate as major acidic fermentation products. Accumulation of these products in the cytoplasm would lead to uncoupling of the membrane potential, and therefore they must be either metabolized rapidly or exported from the cell. E. coli has three membrane-localized formate dehydrogenases (FDHs) that oxidize formate. Two of these have their respective active sites facing the periplasm, and the other is in the cytoplasm. The bidirectional FocA channel translocates formate across the membrane delivering substrate to these FDHs. FocA synthesis is tightly coupled to synthesis of pyruvate formate-lyase (PflB), which generates formate. In this study, we analyze the consequences on the fermentation product spectrum of altering FocA levels, uncoupling FocA from PflB synthesis or blocking formate metabolism. Changing the focA translation initiation codon from GUG to AUG resulted in a 20-fold increase in FocA during fermentation and an ∼3-fold increase in PflB. Nevertheless, the fermentation product spectrum throughout the growth phase remained similar to that of the wild type. Formate, acetate, and succinate were exported, but only formate was reimported by these cells. Lactate accumulated in the growth medium only in mutants lacking FocA, despite retaining active PflB, or when formate could not be metabolized intracellularly. Together, these results indicate that FocA has a strong preference for formate as a substrate in vivo and not other acidic fermentation products. The tight coupling between FocA and PflB synthesis ensures adequate substrate delivery to the appropriate FDH. PMID:23335413

Female sea lamprey shift orientation toward a conspecific chemical cue to escape a sensory trap

USGS Publications Warehouse

Brant, Cory O.; Johnson, Nicholas; Li, Ke; Buchinger, Tyler J.; Li, Weiming

2016-01-01

The sensory trap model of signal evolution hypothesizes that signalers adapt to exploit a cue used by the receiver in another context. Although exploitation of receiver biases can result in conflict between the sexes, deceptive signaling systems that are mutually beneficial drive the evolution of stable communication systems. However, female responses in the nonsexual and sexual contexts may become uncoupled if costs are associated with exhibiting a similar response to a trait in both contexts. Male sea lamprey (Petromyzon marinus) signal with a mating pheromone, 3-keto petromyzonol sulfate (3kPZS), which may be a match to a juvenile cue used by females during migration. Upstream movement of migratory lampreys is partially guided by 3kPZS, but females only move toward 3kPZS with proximal accuracy during spawning. Here, we use in-stream behavioral assays paired with gonad histology to document the transition of female preference for juvenile- and male-released 3kPZS that coincides with the functional shift of 3kPZS as a migratory cue to a mating pheromone. Females became increasingly biased toward the source of synthesized 3kPZS as their maturation progressed into the reproductive phase, at which point, a preference for juvenile odor (also containing 3kPZS naturally) ceased to exist. Uncoupling of female responses during migration and spawning makes the 3kPZS communication system a reliable means of synchronizing mate search. The present study offers a rare example of a transition in female responses to a chemical cue between nonsexual and sexual contexts, provides insights into the origins of stable communication signaling systems.

Novel reptilian uncoupling proteins: molecular evolution and gene expression during cold acclimation.

PubMed

Schwartz, Tonia S; Murray, Shauna; Seebacher, Frank

2008-04-22

Many animals upregulate metabolism in response to cold. Uncoupling proteins (UCPs) increase proton conductance across the mitochondrial membrane and can thereby alleviate damage from reactive oxygen species that may form as a result of metabolic upregulation. Our aim in this study was to determine whether reptiles (Crocodylus porosus) possess UCP genes. If so, we aimed to place reptilian UCP genes within a phylogenetic context and to determine whether the expression of UCP genes is increased during cold acclimation. We provide the first evidence that UCP2 and UCP3 genes are present in reptiles. Unlike in other vertebrates, UCP2 and UPC3 are expressed in liver and skeletal muscle of the crocodile, and both are upregulated in liver during cold acclimation but not in muscle. We identified two transcripts of UCP3, one of which produces a truncated protein similar to the UCP3S transcript in humans, and the resulting protein lacks the predicted nucleotide-binding regulatory domain. Our molecular phylogeny suggests that uncoupling protein 1 (UCP1) is ancestral and has been lost in archosaurs. In birds, UCP3 may have assumed a similar function as UCP1 in mammals, which has important ramifications for understanding endothermic heat production.

Mutations in valosin-containing protein (VCP) decrease ADP/ATP translocation across the mitochondrial membrane and impair energy metabolism in human neurons.

PubMed

Ludtmann, Marthe H R; Arber, Charles; Bartolome, Fernando; de Vicente, Macarena; Preza, Elisavet; Carro, Eva; Houlden, Henry; Gandhi, Sonia; Wray, Selina; Abramov, Andrey Y

2017-05-26

Mutations in the gene encoding valosin-containing protein (VCP) lead to multisystem proteinopathies including frontotemporal dementia. We have previously shown that patient-derived VCP mutant fibroblasts exhibit lower mitochondrial membrane potential, uncoupled respiration, and reduced ATP levels. This study addresses the underlying basis for mitochondrial uncoupling using VCP knockdown neuroblastoma cell lines, induced pluripotent stem cells (iPSCs), and iPSC-derived cortical neurons from patients with pathogenic mutations in VCP Using fluorescent live cell imaging and respiration analysis we demonstrate a VCP mutation/knockdown-induced dysregulation in the adenine nucleotide translocase, which results in a slower rate of ADP or ATP translocation across the mitochondrial membranes. This deregulation can explain the mitochondrial uncoupling and lower ATP levels in VCP mutation-bearing neurons via reduced ADP availability for ATP synthesis. This study provides evidence for a role of adenine nucleotide translocase in the mechanism underlying altered mitochondrial function in VCP-related degeneration, and this new insight may inform efforts to better understand and manage neurodegenerative disease and other proteinopathies. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Mitochondrial uncoupling protein may participate in futile cycling of pyruvate and other monocarboxylates.

PubMed

Jezek, P; Borecký, J

1998-08-01

The physiological role of monocarboxylate transport in brown adipose tissue mitochondria has been reevaluated. We studied pyruvate, alpha-ketoisovalerate, alpha-ketoisocaproate, and phenylpyruvate uniport via the uncoupling protein (UCP1) as a GDP-sensitive swelling in K+ salts induced by valinomycin or by monensin and carbonyl cyanide-p-(trifluoromethoxy)phenylhydrazone in Na+ salts. We have demonstrated that this uniport is inhibited by fatty acids. GDP inhibition in K+ salts was not abolished by an uncoupler, indicating a negligible monocarboxylic acid penetration via the lipid bilayer. In contrast, the electroneutral pyruvate uptake (swelling in ammonium pyruvate or potassium pyruvate induced by change in pH) mediated by the pyruvate carrier was inhibited by its specific inhibitor alpha-cyano-4-hydroxycinnamate but not by fatty acids. Moreover, alpha-cyano-4-hydroxycinnamate enhanced the energization of brown adipose tissue mitochondria, which was monitored fluorometrically by 2-(4-dimethylaminostyryl)-1-methylpyridinium iodide and safranin O. Consequently, we suggest that UCP1 might participate in futile cycling of unipolar ketocarboxylates under certain physiological conditions while expelling these anions from the matrix. The cycle is completed on their return via the pyruvate carrier in an H+ symport mode.

Mitochondrial depolarization in yeast zygotes inhibits clonal expansion of selfish mtDNA.

PubMed

Karavaeva, Iuliia E; Golyshev, Sergey A; Smirnova, Ekaterina A; Sokolov, Svyatoslav S; Severin, Fedor F; Knorre, Dmitry A

2017-04-01

Non-identical copies of mitochondrial DNA (mtDNA) compete with each other within a cell and the ultimate variant of mtDNA present depends on their relative replication rates. Using yeast Saccharomyces cerevisiae cells as a model, we studied the effects of mitochondrial inhibitors on the competition between wild-type mtDNA and mutant selfish mtDNA in heteroplasmic zygotes. We found that decreasing mitochondrial transmembrane potential by adding uncouplers or valinomycin changes the competition outcomes in favor of the wild-type mtDNA. This effect was significantly lower in cells with disrupted mitochondria fission or repression of the autophagy-related genes ATG8 , ATG32 or ATG33 , implying that heteroplasmic zygotes activate mitochondrial degradation in response to the depolarization. Moreover, the rate of mitochondrially targeted GFP turnover was higher in zygotes treated with uncoupler than in haploid cells or untreated zygotes. Finally, we showed that vacuoles of zygotes with uncoupler-activated autophagy contained DNA. Taken together, our data demonstrate that mitochondrial depolarization inhibits clonal expansion of selfish mtDNA and this effect depends on mitochondrial fission and autophagy. These observations suggest an activation of mitochondria quality control mechanisms in heteroplasmic yeast zygotes. © 2017. Published by The Company of Biologists Ltd.

Disrupting nNOS-PSD-95 coupling in the hippocampal dentate gyrus promotes extinction memory retrieval.

PubMed

Li, Jun; Han, Zhou; Cao, Bo; Cai, Cheng-Yun; Lin, Yu-Hui; Li, Fei; Wu, Hai-Ying; Chang, Lei; Luo, Chun-Xia; Zhu, Dong-Ya

2017-11-04

Granule cells in the dentate gyrus regenerate constantly in adult hippocampus and then integrate into neural circuits in the hippocampus thereby providing the neural basis for learning and memory. Promoting the neurogenesis in the hippocampus facilitates learning and memory such as spatial learning, object identification, and extinction learning. The interaction between neuronal nitric oxide synthase (nNOS) and postsynaptic density protein-95 (PSD-95) is reported to negatively regulate neurogenesis in brain, so we hypothesized that disrupting this interaction might facilitate the neurogenesis in the dentate gyrus (DG) and thus enhance the extinction memory retrieval of fear learning. We found that uncoupling the nNOS-PSD-95 complex in remote contextual fear condition promoted both neuronal proliferation and survival in the DG, contributing to an enhanced retrieval of the extinction memory. Moreover, the nNOS-PSD-95 uncoupling-induced neurogenesis may be mediated by the extracellular signal-regulated kinase (ERK) as the phosphorylation level of ERK1/2 was increased after uncoupling. These findings suggest that the nNOS-PSD-95 complex may serve as a novel target for the treatment of post-traumatic stress disorder (PTSD). Copyright © 2017 Elsevier Inc. All rights reserved.

The cytotoxic effects of brown Cuban propolis depend on the nemorosone content and may be mediated by mitochondrial uncoupling.

PubMed

Pardo Andreu, Gilberto L; Reis, Felippe H Z; Dalalio, Felipe M; Nuñez Figueredo, Yanier; Cuesta Rubio, Osmany; Uyemura, Sergio A; Curti, Carlos; Alberici, Luciane C

2015-02-25

Three main types of Cuban propolis directly related to their secondary metabolite composition have been identified: brown, red and yellow propolis; the former is majoritarian and is characterized by the presence of nemorosone. In this study, brown Cuban propolis extracts were found cytotoxic against HepG2 cells and primary rat hepatocytes, in close association with the nemorosone contents. In mitochondria isolated from rat liver the extracts displayed uncoupling activity, which was demonstrated by the increase in succinate-supported state 4 respiration rates, dissipation of mitochondrial membrane potential, Ca(2+) release from Ca(2+)-loaded mitochondria, and a marked ATP depletion. As in cells, the degree of such mitotoxic events was closely correlated to the nemorosone content. The propolis extracts that do not contain nemorosone were neither cytotoxic nor mitotoxic, except R-29, whose detrimental effect upon cells and mitochondria could be mediated by its isoflavonoids and chalcones components, well known mitochondrial uncouplers. Our results at least partly unravel the cytotoxic mechanism of Cuban propolis, particularly regarding brown propolis, and raise concerns about the toxicological implication of Cuban propolis consumption. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

The role of soil moisture in land surface-atmosphere coupling: climate model sensitivity experiments over India

NASA Astrophysics Data System (ADS)

Williams, Charles; Turner, Andrew

2015-04-01

It is generally acknowledged that anthropogenic land use changes, such as a shift from forested land into irrigated agriculture, may have an impact on regional climate and, in particular, rainfall patterns in both time and space. India provides an excellent example of a country in which widespread land use change has occurred during the last century, as the country tries to meet its growing demand for food. Of primary concern for agriculture is the Indian summer monsoon (ISM), which displays considerable seasonal and subseasonal variability. Although it is evident that changing rainfall variability will have a direct impact on land surface processes (such as soil moisture variability), the reverse impact is less well understood. However, the role of soil moisture in the coupling between the land surface and atmosphere needs to be properly explored before any potential impact of changing soil moisture variability on ISM rainfall can be understood. This paper attempts to address this issue, by conducting a number of sensitivity experiments using a state-of-the-art climate model from the UK Meteorological Office Hadley Centre: HadGEM2. Several experiments are undertaken, with the only difference between them being the extent to which soil moisture is coupled to the atmosphere. Firstly, the land surface is fully coupled to the atmosphere, globally (as in standard model configurations); secondly, the land surface is entirely uncoupled from the atmosphere, again globally, with soil moisture values being prescribed on a daily basis; thirdly, the land surface is uncoupled from the atmosphere over India but fully coupled elsewhere; and lastly, vice versa (i.e. the land surface is coupled to the atmosphere over India but uncoupled elsewhere). Early results from this study suggest certain 'hotspot' regions where the impact of soil moisture coupling/uncoupling may be important, and many of these regions coincide with previous studies. Focusing on the third experiment, i.e. uncoupled over India and coupled elsewhere, preliminary results suggest an increase in rainfall, surface temperature and pressure over northern India and the Himalayas, as well as a decrease in rainfall over the Bay of Bengal and the Maritime Continent. Other metrics, such as the northward propagation of intraseasonal rainfall variability and sensible and latent heat fluxes, are also discussed.

Uncoupling protein 1 binds one nucleotide per monomer and is stabilized by tightly bound cardiolipin

PubMed Central

Lee, Yang; Willers, Chrissie; Kunji, Edmund R. S.; Crichton, Paul G.

2015-01-01

Uncoupling protein 1 (UCP1) catalyzes fatty acid-activated, purine nucleotide-sensitive proton leak across the mitochondrial inner membrane of brown adipose tissue to produce heat, and could help combat obesity and metabolic disease in humans. Studies over the last 30 years conclude that the protein is a dimer, binding one nucleotide molecule per two proteins, and unlike the related mitochondrial ADP/ATP carrier, does not bind cardiolipin. Here, we have developed novel methods to purify milligram amounts of UCP1 from native sources by using covalent chromatography that, unlike past methods, allows the protein to be prepared in defined conditions, free of excess detergent and lipid. Assessment of purified preparations by TLC reveal that UCP1 retains tightly bound cardiolipin, with a lipid phosphorus content equating to three molecules per protein, like the ADP/ATP carrier. Cardiolipin stabilizes UCP1, as demonstrated by reconstitution experiments and thermostability assays, indicating that the lipid has an integral role in the functioning of the protein, similar to other mitochondrial carriers. Furthermore, we find that UCP1 is not dimeric but monomeric, as indicated by size exclusion analysis, and has a ligand titration profile in isothermal calorimetric measurements that clearly shows that one nucleotide binds per monomer. These findings reveal the fundamental composition of UCP1, which is essential for understanding the mechanism of the protein. Our assessment of the properties of UCP1 indicate that it is not unique among mitochondrial carriers and so is likely to use a common exchange mechanism in its primary function in brown adipose tissue mitochondria. PMID:26038550

Strategies for efficiently selecting PHA producing mixed microbial cultures using complex feedstocks: Feast and famine regime and uncoupled carbon and nitrogen availabilities.

PubMed

Oliveira, Catarina S S; Silva, Carlos E; Carvalho, Gilda; Reis, Maria A

2017-07-25

Production of polyhydroxyalkanoates (PHAs) by open mixed microbial cultures (MMCs) has been attracting increasing interest as an alternative technology to PHA production by pure cultures, due to the potential for lower costs associated with the use of open systems (eliminating the requirement for sterile conditions) and the utilisation of cheap feedstock (industrial and agricultural wastes). Such technology relies on the efficient selection of an MMC enriched in PHA-accumulating organisms. Fermented cheese whey, a protein-rich complex feedstock, has been used previously to produce PHA using the feast and famine regime for selection of PHA accumulating cultures. While this selection strategy was found efficient when operated at relatively low organic loading rate (OLR, 2g-CODL -1 d -1 ), great instability and low selection efficiency of PHA accumulating organisms were observed when higher OLR (ca. 6g-CODL -1 d -1 ) was applied. High organic loading is desirable as a means to enhance PHA productivity. In the present study, a new selection strategy was tested with the aim of improving selection for high OLR. It was based on uncoupling carbon and nitrogen supply and was implemented and compared with the conventional feast and famine strategy. For this, two selection reactors were fed with fermented cheese whey applying an OLR of ca. 8.5g-CODL -1 (with 3.8g-CODL -1 resulting from organic acids and ethanol), and operated in parallel under similar conditions, except for the timing of nitrogen supplementation. Whereas in the conventional strategy nitrogen and carbon substrates were added simultaneously at the beginning of the cycle, in the uncoupled substrates strategy, nitrogen addition was delayed to the end of the feast phase (i.e. after exogenous carbon was exhausted). The two different strategies selected different PHA-storing microbial communities, dominated by Corynebacterium and a Xantomonadaceae, respectively with the conventional and the new approaches. The new strategy originated a more efficient PHA-production process than the conventional one (global PHA productivity of 6.09g-PHAL -1 d -1 and storage yield of 0.96 versus 2.55g-PHAL -1 d -1 and 0.86, respectively). Dissociation between the feast to famine length ratio (F/F) and storage efficiency was shown to be possible with the new strategy, allowing selection of an efficient PHA-storing culture with complex feedstock under high organic loading rates. Copyright © 2016 Elsevier B.V. All rights reserved.

Free-stream disturbance, continuous Eigenfunctions, boundary-layer instability and transition

NASA Technical Reports Server (NTRS)

Grosch, C. E.

1980-01-01

A rational foundation is presented for the application of the linear shear flows to transition prediction, and an explicit method is given for carrying out the necessary calculations. The expansions used are shown to be complete. Sample calculations show that a typical boundary layer is very sensitive to vorticity disturbances in the inner boundary layer, near the critical layer. Vorticity disturbances three or four boundary layer thicknesses above the boundary are nearly uncoupled from the boundary layer in that the amplitudes of the discrete Tollmien-Schlicting waves are an extremely small fraction of the amplitude of the disturbance.

Inhibition of electron transfer and uncoupling effects by emodin and emodinanthrone in Escherichia coli

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ubbink-Kok, T.; Anderson, J.A.; Konings, W.N.

1986-07-01

The anthraquinones emodin (1,3,delta-trihydroxy-6-methylanthraquinone) and emodinanthrone (1,3,8-trihydroxy-6-methylanthrone) inhibited respiration-driven solute transport at micromolar concentrations in membrane vesicles of Escherichia coli. This inhibition was enhanced by Ca ions. The inhibitory action on solute transport is caused by inhibition of electron flow in the respiratory chain, most likely at the level between ubiquinone and cytochrome b, and by dissipation of the proton motive force. The uncoupling action was confirmed by studies on the proton motive force in beef heart cytochrome oxidase proteoliposomes. These two effects on energy transduction in cytoplasmic membranes explain the antibiotic properties of emodin and emodinanthrone.

Inhibition of electron transfer and uncoupling effects by emodin and emodinanthrone in Escherichia coli.

PubMed

Ubbink-Kok, T; Anderson, J A; Konings, W N

1986-07-01

The anthraquinones emodin (1,3,delta-trihydroxy-6-methylanthraquinone) and emodinanthrone (1,3,8-trihydroxy-6-methylanthrone) inhibited respiration-driven solute transport at micromolar concentrations in membrane vesicles of Escherichia coli. This inhibition was enhanced by Ca ions. The inhibitory action on solute transport is caused by inhibition of electron flow in the respiratory chain, most likely at the level between ubiquinone and cytochrome b, and by dissipation of the proton motive force. The uncoupling action was confirmed by studies on the proton motive force in beef heart cytochrome oxidase proteoliposomes. These two effects on energy transduction in cytoplasmic membranes explain the antibiotic properties of emodin and emodinanthrone.

Uncoupling proteins of invertebrates: A review.

PubMed

Slocinska, Malgorzata; Barylski, Jakub; Jarmuszkiewicz, Wieslawa

2016-09-01

Uncoupling proteins (UCPs) mediate inducible proton conductance in the mitochondrial inner membrane. Herein, we summarize our knowledge regarding UCPs in invertebrates. Since 2001, the presence of UCPs has been demonstrated in nematodes, mollusks, amphioxi, and insects. We discuss the following important issues concerning invertebrate UCPs: their evolutionary relationships, molecular and functional properties, and physiological impact. Evolutionary analysis indicates that the branch of vertebrate and invertebrate UCP4-5 diverged early in the evolutionary process prior to the divergence of the animal groups. Several proposed physiological roles of invertebrate UCPs are energy control, metabolic balance, and preventive action against oxidative stress. © 2016 IUBMB Life, 68(9):691-699, 2016. © 2016 International Union of Biochemistry and Molecular Biology.

Potential roles for uncoupling proteins in HIV lipodystrophy.

PubMed

Nolan, David; Pace, Craig

2004-07-01

The 'HIV lipodystrophy syndrome' consists of several distinct components, including lipoatrophy (pathological subcutaneous fat loss), lipohypertrophy (abdominal/visceral adiposity), and metabolic complications including insulin resistance and dyslipidemia. Lipoatrophy appears to represent an adipose tissue-specific form of mitochondrial toxicity associated strongly with stavudine NRTI therapy, whilst the 'metabolic syndrome' phenotype is associated with HIV protease inhibitor therapy. In this context, the role of uncoupling proteins (UCPs) in modulating resting energy expenditure in response to elevated fatty acid flux associated with the 'metabolic syndrome' is supported by clinical data as well as findings of elevated adipose tissue UCP expression. The role of UCPs in this syndrome therefore exemplifies the multifactorial nature of these antiretroviral therapy complications.

Multi-beam linear accelerator EVT

NASA Astrophysics Data System (ADS)

Teryaev, Vladimir E.; Kazakov, Sergey Yu.; Hirshfield, Jay L.

2016-09-01

A novel electron multi-beam accelerator is presented. The accelerator, short-named EVT (Electron Voltage Transformer) belongs to the class of two-beam accelerators. It combines an RF generator and essentially an accelerator within the same vacuum envelope. Drive beam-lets and an accelerated beam are modulated in RF modulators and then bunches pass into an accelerating structure, comprising uncoupled with each other and inductive tuned cavities, where the energy transfer from the drive beams to the accelerated beam occurs. A phasing of bunches is solved by choice correspond distances between gaps of the adjacent cavities. Preliminary results of numerical simulations and the initial specification of EVT operating in S-band, with a 60 kV gun and generating a 2.7 A, 1.1 MV beam at its output is presented. A relatively high efficiency of 67% and high design average power suggest that EVT can find its use in industrial applications.

Multi-beam linear accelerator EVT

DOE PAGES

Teryaev, Vladimir E.; Kazakov, Sergey Yu.; Hirshfield, Jay L.

2016-03-29

A novel electron multi-beam accelerator is presented. The accelerator, short-named EVT (Electron Voltage Transformer) belongs to the class of two-beam accelerators. It combines an RF generator and essentially an accelerator within the same vacuum envelope. Drive beam-lets and an accelerated beam are modulated in RF modulators and then bunches pass into an accelerating structure, comprising uncoupled with each other and inductive tuned cavities, where the energy transfer from the drive beams to the accelerated beam occurs. A phasing of bunches is solved by choice correspond distances between gaps of the adjacent cavities. Preliminary results of numerical simulations and the initialmore » specification of EVT operating in S-band, with a 60 kV gun and generating a 2.7 A, 1.1 MV beam at its output is presented. Furthermore, a relatively high efficiency of 67% and high design average power suggest that EVT can find its use in industrial applications.« less

Comment on twinning in YNbO sub 4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsunekawa, S.

1992-04-01

The paper contains statements about an analogue of ZrO{sub 2} and the twins. The analogue is suggestive in connection with yttria-partially-stabilized zirconia, but an error is found in the description of the twins in YNbO{sub 4}. Because YNbO{sub 4} performs a pure, uncoupled ferroelastic transition (thermoelastic martensitic transformation), the composition plane is determined by the following formulas 4/mF2/m: x = pz and x = {minus}z/p, p = (b + (a{sup 2} + b{sup 2}){sup 1/2})/a a = (x{sub 33} {minus} x{sub 11})/2, b = {minus} tan ({beta} {minus} 90{degrees})/2) x{sub 11} = (a{sup I} {minus} a{sub 0})/a{sub 0}, x{sub 33}more » = (c{sup 1} {minus} a{sub 0})/a{sub 0} where a{sub 0} is the lattice parameter of a in the tetragonal phase, and a{sup I} and c{sup I} are the parameters of a and c, respectively, in the monoclinic phase represented by the I-lattice. The value of p at room temperature can be estimated by using the parameters included in this paper.« less

Real-Time X-Ray Transmission Microscopy of Solidifying Al-In Alloys

NASA Technical Reports Server (NTRS)

Curreri, Peter A.; Kaukler, William F.

1997-01-01

Real-time observations of transparent analog materials have provided insight, yet the results of these observations are not necessarily representative of opaque metallic systems. In order to study the detailed dynamics of the solidification process, we develop the technologies needed for real-time X ray microscopy of solidifying metallic systems, which has not previously been feasible with the necessary resolution, speed, and contrast. In initial studies of Al-In monotectic alloys unidirectionally solidified in an X-ray transparent furnace, in situ records of the evolution of interface morphologies, interfacial solute accumulation, and formation of the monotectic droplets were obtained for the first time: A radiomicrograph of Al-30In grown during aircraft parabolic maneuvers is presented, showing the volumetric phase distribution in this specimen. The benefits of using X-ray microscopy for postsolidification metallography include ease of specimen preparation, increased sensitivity, and three-dimensional analysis of phase distribution. Imaging of the solute boundary layer revealed that the isoconcentration lines are not parallel (as is often assumed) to the growth interface. Striations in the solidified crystal did not accurately decorate the interface position and shape. The monotectic composition alloy under some conditions grew in an uncoupled manner.

[Heart rate variability study based on a novel RdR RR Intervals Scatter Plot].

PubMed

Lu, Hongwei; Lu, Xiuyun; Wang, Chunfang; Hua, Youyuan; Tian, Jiajia; Liu, Shihai

2014-08-01

On the basis of Poincare scatter plot and first order difference scatter plot, a novel heart rate variability (HRV) analysis method based on scatter plots of RR intervals and first order difference of RR intervals (namely, RdR) was proposed. The abscissa of the RdR scatter plot, the x-axis, is RR intervals and the ordinate, y-axis, is the difference between successive RR intervals. The RdR scatter plot includes the information of RR intervals and the difference between successive RR intervals, which captures more HRV information. By RdR scatter plot analysis of some records of MIT-BIH arrhythmias database, we found that the scatter plot of uncoupled premature ventricular contraction (PVC), coupled ventricular bigeminy and ventricular trigeminy PVC had specific graphic characteristics. The RdR scatter plot method has higher detecting performance than the Poincare scatter plot method, and simpler and more intuitive than the first order difference method.

Human 'brite/beige' adipocytes develop from capillary networks, and their implantation improves metabolic homeostasis in mice.

PubMed

Min, So Yun; Kady, Jamie; Nam, Minwoo; Rojas-Rodriguez, Raziel; Berkenwald, Aaron; Kim, Jong Hun; Noh, Hye-Lim; Kim, Jason K; Cooper, Marcus P; Fitzgibbons, Timothy; Brehm, Michael A; Corvera, Silvia

2016-03-01

Uncoupling protein 1 (UCP1) is highly expressed in brown adipose tissue, where it generates heat by uncoupling electron transport from ATP production. UCP1 is also found outside classical brown adipose tissue depots, in adipocytes that are termed 'brite' (brown-in-white) or 'beige'. In humans, the presence of brite or beige (brite/beige) adipocytes is correlated with a lean, metabolically healthy phenotype, but whether a causal relationship exists is not clear. Here we report that human brite/beige adipocyte progenitors proliferate in response to pro-angiogenic factors, in association with expanding capillary networks. Adipocytes formed from these progenitors transform in response to adenylate cyclase activation from being UCP1 negative to being UCP1 positive, which is a defining feature of the beige/brite phenotype, while displaying uncoupled respiration. When implanted into normal chow-fed, or into high-fat diet (HFD)-fed, glucose-intolerant NOD-scid IL2rg(null) (NSG) mice, brite/beige adipocytes activated in vitro enhance systemic glucose tolerance. These adipocytes express neuroendocrine and secreted factors, including the pro-protein convertase PCSK1, which is strongly associated with human obesity. Pro-angiogenic conditions therefore drive the proliferation of human beige/brite adipocyte progenitors, and activated beige/brite adipocytes can affect systemic glucose homeostasis, potentially through a neuroendocrine mechanism.

Human ‘brite / beige’ adipocytes develop from capillary networks and their implantation improves metabolic homeostasis in mice

PubMed Central

Min, So Yun; Kady, Jamie; Nam, Minwoo; Rojas-Rodriguez, Raziel; Berkenwald, Aaron; Kim, Jong Hun; Noh, Hye-Lim; Kim, Jason K.; Cooper, Marcus P.; Fitzgibbons, Timothy; Brehm, Michael A.; Corvera, Silvia

2015-01-01

The uncoupling protein 1 (UCP1) is highly expressed in brown adipose tissue, where it generates heat by uncoupling electron transport from ATP production. UCP1 is also found outside classical brown adipose tissue depots1–4, in adipocytes termed ‘brite’ (brown-in-white) or ‘beige’. In humans, the presence of ‘brite/beige’ adipocytes correlates with a lean, metabolically healthy phenotype5–8, but whether a causal relationship exists is not clear. Here we report that human ‘brite/beige’ adipocyte progenitors proliferate in response to pro-angiogenic factors, in association with expanding capillary networks. Adipocytes formed from these progenitors transform from being UCP1-negative to UCP1-positive in response to adenylate cyclase activation, a defining feature of the ‘beige/brite’ phenotype, and display uncoupled respiration. When implanted into normal or high fat diet-fed, glucose intolerant NOD-scid IL2rgnull mice, activated ‘brite/beige’ adipocytes enhance systemic glucose tolerance. These adipocytes express neuroendocrine and secreted factors, including the pro-protein convertase PCSK1, which is strongly associated with human obesity. Thus, pro-angiogenic conditions drive proliferation of human ‘beige/brite’ adipocyte progenitors, and activated ‘beige/brite’ adipocytes can affect systemic glucose homeostasis, potentially through a neuroendocrine mechanism. PMID:26808348

Insulin-induced generation of reactive oxygen species and uncoupling of nitric oxide synthase underlie the cerebrovascular insulin resistance in obese rats

PubMed Central

Katakam, Prasad V G; Snipes, James A; Steed, Mesia M; Busija, David W

2012-01-01

Hyperinsulinemia accompanying insulin resistance (IR) is an independent risk factor for stroke. The objective is to examine the cerebrovascular actions of insulin in Zucker obese (ZO) rats with IR and Zucker lean (ZL) control rats. Diameter measurements of cerebral arteries showed diminished insulin-induced vasodilation in ZO compared with ZL. Endothelial denudation revealed vasoconstriction to insulin that was greater in ZO compared with ZL. Nonspecific inhibition of nitric oxide synthase (NOS) paradoxically improved vasodilation in ZO. Scavenging of reactive oxygen species (ROS), supplementation of tetrahydrobiopterin (BH4) precursor, and inhibition of neuronal NOS or NADPH oxidase or cyclooxygenase (COX) improved insulin-induced vasodilation in ZO. Immunoblot experiments revealed that insulin-induced phosphorylation of Akt, endothelial NOS, and expression of GTP cyclohydrolase-I (GTP-CH) were diminished, but phosphorylation of PKC and ERK was enhanced in ZO arteries. Fluorescence studies showed increased ROS in ZO arteries in response to insulin that was sensitive to NOS inhibition and BH4 supplementation. Thus, a vicious cycle of abnormal insulin-induced ROS generation instigating NOS uncoupling leading to further ROS production underlies the cerebrovascular IR in ZO rats. In addition, decreased bioavailability and impaired synthesis of BH4 by GTP-CH induced by insulin promoted NOS uncoupling. PMID:22234336

Which complexity of regional climate system models is essential for downscaling anthropogenic climate change in the Northwest European Shelf?

NASA Astrophysics Data System (ADS)

Mathis, Moritz; Elizalde, Alberto; Mikolajewicz, Uwe

2018-04-01

Climate change impact studies for the Northwest European Shelf (NWES) make use of various dynamical downscaling strategies in the experimental setup of regional ocean circulation models. Projected change signals from coupled and uncoupled downscalings with different domain sizes and forcing global and regional models show substantial uncertainty. In this paper, we investigate influences of the downscaling strategy on projected changes in the physical and biogeochemical conditions of the NWES. Our results indicate that uncertainties due to different downscaling strategies are similar to uncertainties due to the choice of the parent global model and the downscaling regional model. Downscaled change signals reveal to depend stronger on the downscaling strategy than on the model skills in simulating present-day conditions. Uncoupled downscalings of sea surface temperature (SST) changes are found to be tightly constrained by the atmospheric forcing. The incorporation of coupled air-sea interaction, by contrast, allows the regional model system to develop independently. Changes in salinity show a higher sensitivity to open lateral boundary conditions and river runoff than to coupled or uncoupled atmospheric forcings. Dependencies on the downscaling strategy for changes in SST, salinity, stratification and circulation collectively affect changes in nutrient import and biological primary production.

Dose Dependent Effects of Reactive Oxygen and Nitrogen Species on the Function of Neuronal Nitric Oxide Synthase

PubMed Central

Sun, Jian; Druhan, Lawrence J.; Zweier, Jay L.

2014-01-01

Reactive nitrogen species (RNS) and oxygen species (ROS) have been reported to modulate the function of nitric oxide synthase (NOS); however, the precise dosedependent effects of specific RNS and ROS on NOS function are unknown. Questions remain unanswered regarding whether pathophysiological levels of RNS and ROS alter NOS function, and if this alteration is reversible. We measured the effects of peroxynitrite (ONOO-), superoxide (O2.-), hydroxyl radical (.OH), and H2O2 on nNOS activity. The results showed that NO production was inhibited in a dose-dependent manner by all four oxidants, but only O2.- and ONOO- were inhibitory at pathophysiological concentrations (≤ 50 μM). Subsequent addition of tetrahydrobiopterin (BH4) fully restored activity after O2.- exposure, while BH4 partially rescued the activity decrease induced by the other three oxidants. Furthermore, treatment with either ONOO- or O2.- stimulated nNOS uncoupling with decreased NO and enhanced O2.- generation. Thus, nNOS is reversibly uncoupled by O2.- (≤ 50 μM), but irreversibly uncoupled and inactivated by ONOO-. Additionally, we observed that the mechanism by which oxidative stress alters nNOS activity involves not only BH4 oxidation, but also nNOS monomerization as well as possible degradation of the heme. PMID:18201545

Glutathione Decrement Drives Thermogenic Program In Adipose Cells.

PubMed

Lettieri Barbato, Daniele; Tatulli, Giuseppe; Maria Cannata, Stefano; Bernardini, Sergio; Aquilano, Katia; Ciriolo, Maria R

2015-08-11

Adipose tissue metabolically adapts to external stimuli. We demonstrate that the induction of the thermogenic program in white adipocytes, through cold exposure in mice or in vitro adrenergic stimulation, is accompanied by a decrease in the intracellular content of glutathione (GSH). Moreover, the treatment with a GSH depleting agent, buthionine sulfoximine (BSO), recapitulates the effect of cold exposure resulting in the induction of thermogenic program. In particular, BSO treatment leads to enhanced uncoupling respiration as demonstrated by increased expression of thermogenic genes (e.g. Ucp1, Ppargc1a), augmented oxygen consumption and decreased mitochondrial transmembrane potential. Buffering GSH decrement by pre-treatment with GSH ester prevents the up-regulation of typical markers of uncoupling respiration. We demonstrate that FoxO1 activation is responsible for the conversion of white adipocytes into a brown phenotype as the "browning" effects of BSO are completely abrogated in cells down-regulating FoxO1. In mice, the BSO-mediated up-regulation of uncoupling genes results in weight loss that is at least in part ascribed to adipose tissue mass reduction. The induction of thermogenic program has been largely proposed to counteract obesity-related diseases. Based on these findings, we propose GSH as a novel therapeutic target to increase energy expenditure in adipocytes.

An Unprecedented NADPH Domain Conformation in Lysine Monooxygenase NbtG Provides Insights into Uncoupling of Oxygen Consumption from Substrate Hydroxylation

DOE PAGES

Binda, Claudia; Robinson, Reeder M.; Martin del Campo, Julia S.; ...

2015-03-23

N-hydroxylating monooxygenases (NMOs) are involved in the biosynthesis of iron-chelating hydroxamate-containing siderophores that play a role in microbial virulence. These flavoenzymes catalyze the NADPH- and oxygen-dependent hydroxylation of amines, such as those found on the side chains of lysine and ornithine. In this work we report the biochemical and structural characterization of Nocardia farcinica Lys monooxygenase (NbtG), which has similar biochemical properties to mycobacterial homologs. NbtG is also active on D-Lys although it binds L-Lys with a higher affinity. Differently from the ornithine monooxygenases PvdA, SidA and KtzI, NbtG can use both NADH and NADPH and is highly uncoupled, producingmore » more superoxide and hydrogen peroxide than hydroxylated Lys. The crystal structure of NbtG solved at 2.4 Å resolution revealed an unexpected protein conformation with a 30° rotation of the NAD(P)H domain with respect to the FAD domain that precludes binding of the nicotinamide cofactor. This “occluded” structure may explain the biochemical properties of NbtG, specifically with regard to the substantial uncoupling and limited stabilization of the C4a-hydroperoxyflavin intermediate. We discuss the biological implications of these findings.« less

Structural and chemical requirements for hydroxychlorobiphenyls to uncouple rat liver mitochondria and potentiation of uncoupling with aroclor 1254.

PubMed

Ebner, K V; Braselton, W E

1987-01-01

Rat hepatic mitochondrial permeability and succinate + valinomycin-dependent swelling were studied in the presence of hydroxy derivatives of polychlorinated biphenyls (PCBOHs), Aroclor 1254 (ARO) and combinations of both. PCBOHs with two or more chlorines and pKas greater than 8.0 (PCBOH I) induced passive swelling in a potassium acetate-sucrose medium (pH 7.2), maximally stimulated succinate respiration, and suppressed ADP-stimulated H+ uptake. Mono- and certain dichlorinated biphenylols with similar high pKas (PCBOH II) were ineffective. Para-hydroxy PCBs with chlorines substituted in the 3,5 positions and with pKas near 6.8 (PCBOH III) inhibited succinate + valinomycin swelling and ADP-stimulated H+ and oxygen uptake. The efficacy of both PCBOH I and III derivatives required the presence of a hydroxyl moiety and increased directly with the degree of chlorination. Coplanarity was not a determining factor for PCBOH I compounds. ARO activated succinate + valinomycin swelling at low concentrations (3-25 nmol/mg protein) but inhibited at higher concentrations (greater than 40 nmol/mg). Activating concentrations of ARO potentiated the influence of PCBOHs on mitochondria. The uncoupling effects of the PCBOHs and ARO involved permeability changes of the inner membrane, respiratory inhibition, or combinations of both.

Deterioration of physical performance and cognitive function in rats with short-term high-fat feeding.

PubMed

Murray, Andrew J; Knight, Nicholas S; Cochlin, Lowri E; McAleese, Sara; Deacon, Robert M J; Rawlins, J Nicholas P; Clarke, Kieran

2009-12-01

Efficiency, defined as the amount of work produced for a given amount of oxygen consumed, is a key determinant of endurance capacity, and can be altered by metabolic substrate supply, in that fatty acid oxidation is less efficient than glucose oxidation. It is unclear, however, whether consumption of a high-fat diet would be detrimental or beneficial for endurance capacity, due to purported glycogen-sparing properties. In addition, a high-fat diet over several months leads to cognitive impairment. Here, we tested the hypothesis that short-term ingestion of a high-fat diet (55% kcal from fat) would impair exercise capacity and cognitive function in rats, compared with a control chow diet (7.5% kcal from fat) via mitochondrial uncoupling and energy deprivation. We found that rats ran 35% less far on a treadmill and showed cognitive impairment in a maze test with 9 d of high-fat feeding, with respiratory uncoupling in skeletal muscle mitochondria, associated with increased uncoupling protein (UCP3) levels. Our results suggest that high-fat feeding, even over short periods of time, alters skeletal muscle UCP3 expression, affecting energy production and physical performance. Optimization of nutrition to maximize the efficiency of mitochondrial ATP production could improve energetics in athletes and patients with metabolic abnormalities.

Glutathione Decrement Drives Thermogenic Program In Adipose Cells

PubMed Central

Lettieri Barbato, Daniele; Tatulli, Giuseppe; Maria Cannata, Stefano; Bernardini, Sergio; Aquilano, Katia; Ciriolo, Maria R.

2015-01-01

Adipose tissue metabolically adapts to external stimuli. We demonstrate that the induction of the thermogenic program in white adipocytes, through cold exposure in mice or in vitro adrenergic stimulation, is accompanied by a decrease in the intracellular content of glutathione (GSH). Moreover, the treatment with a GSH depleting agent, buthionine sulfoximine (BSO), recapitulates the effect of cold exposure resulting in the induction of thermogenic program. In particular, BSO treatment leads to enhanced uncoupling respiration as demonstrated by increased expression of thermogenic genes (e.g. Ucp1, Ppargc1a), augmented oxygen consumption and decreased mitochondrial transmembrane potential. Buffering GSH decrement by pre-treatment with GSH ester prevents the up-regulation of typical markers of uncoupling respiration. We demonstrate that FoxO1 activation is responsible for the conversion of white adipocytes into a brown phenotype as the “browning” effects of BSO are completely abrogated in cells down-regulating FoxO1. In mice, the BSO-mediated up-regulation of uncoupling genes results in weight loss that is at least in part ascribed to adipose tissue mass reduction. The induction of thermogenic program has been largely proposed to counteract obesity-related diseases. Based on these findings, we propose GSH as a novel therapeutic target to increase energy expenditure in adipocytes. PMID:26260892

Systems Analysis of the Response of Photosynthesis, Metabolism, and Growth to an Increase in Irradiance in the Photosynthetic Model Organism Chlamydomonas reinhardtii[C][W][OPEN

PubMed Central

Mettler, Tabea; Mühlhaus, Timo; Hemme, Dorothea; Schöttler, Mark-Aurel; Rupprecht, Jens; Idoine, Adam; Veyel, Daniel; Pal, Sunil Kumar; Yaneva-Roder, Liliya; Winck, Flavia Vischi; Sommer, Frederik; Vosloh, Daniel; Seiwert, Bettina; Erban, Alexander; Burgos, Asdrubal; Arvidsson, Samuel; Schönfelder, Stephanie; Arnold, Anne; Günther, Manuela; Krause, Ursula; Lohse, Marc; Kopka, Joachim; Nikoloski, Zoran; Mueller-Roeber, Bernd; Willmitzer, Lothar; Bock, Ralph; Schroda, Michael; Stitt, Mark

2014-01-01

We investigated the systems response of metabolism and growth after an increase in irradiance in the nonsaturating range in the algal model Chlamydomonas reinhardtii. In a three-step process, photosynthesis and the levels of metabolites increased immediately, growth increased after 10 to 15 min, and transcript and protein abundance responded by 40 and 120 to 240 min, respectively. In the first phase, starch and metabolites provided a transient buffer for carbon until growth increased. This uncouples photosynthesis from growth in a fluctuating light environment. In the first and second phases, rising metabolite levels and increased polysome loading drove an increase in fluxes. Most Calvin-Benson cycle (CBC) enzymes were substrate-limited in vivo, and strikingly, many were present at higher concentrations than their substrates, explaining how rising metabolite levels stimulate CBC flux. Rubisco, fructose-1,6-biosphosphatase, and seduheptulose-1,7-bisphosphatase were close to substrate saturation in vivo, and flux was increased by posttranslational activation. In the third phase, changes in abundance of particular proteins, including increases in plastidial ATP synthase and some CBC enzymes, relieved potential bottlenecks and readjusted protein allocation between different processes. Despite reasonable overall agreement between changes in transcript and protein abundance (R2 = 0.24), many proteins, including those in photosynthesis, changed independently of transcript abundance. PMID:24894045

A SNP uncoupling Mina expression from the TGFβ signaling pathway

PubMed Central

Lian, Shang L.; Mihi, Belgacem; Koyanagi, Madoka; Nakayama, Toshinori

2017-01-01

Abstract Introduction Mina is a JmjC family 2‐oxoglutarate oxygenase with pleiotropic roles in cell proliferation, cancer, T cell differentiation, pulmonary inflammation, and intestinal parasite expulsion. Although Mina expression varies according to cell‐type, developmental stage and activation state, its transcriptional regulation is poorly understood. Across inbred mouse strains, Mina protein level exhibits a bimodal distribution, correlating with inheritance of a biallelic haplotype block comprising 21 promoter/intron 1‐region SNPs. We previously showed that heritable differences in Mina protein level are transcriptionally regulated. Methods Accordingly, we decided to test the hypothesis that at least one of the promoter/intron 1‐region SNPs perturbs a Mina cis‐regulatory element (CRE). Here, we have comprehensively scanned for CREs across a Mina locus‐spanning 26‐kilobase genomic interval. Results We discovered 8 potential CREs and functionally validated 4 of these, the strongest of which (E2), residing in intron 1, contained a SNP whose BALB/c—but not C57Bl/6 allele—abolished both Smad3 binding and transforming growth factor beta (TGFβ) responsiveness. Conclusions Our results demonstrate the TGFβ signaling pathway plays a critical role in regulating Mina expression and SNP rs4191790 controls heritable variation in Mina expression level, raising important questions regarding the evolution of an allele that uncouples Mina expression from the TGFβ signaling pathway. PMID:28967702

An siRNA-based method for efficient silencing of gene expression in mature brown adipocytes.

PubMed

Isidor, Marie S; Winther, Sally; Basse, Astrid L; Petersen, M Christine H; Cannon, Barbara; Nedergaard, Jan; Hansen, Jacob B

2016-01-01

Brown adipose tissue is a promising therapeutic target for opposing obesity, glucose intolerance and insulin resistance. The ability to modulate gene expression in mature brown adipocytes is important to understand brown adipocyte function and delineate novel regulatory mechanisms of non-shivering thermogenesis. The aim of this study was to optimize a lipofection-based small interfering RNA (siRNA) transfection protocol for efficient silencing of gene expression in mature brown adipocytes. We determined that a critical parameter was to deliver the siRNA to mature adipocytes by reverse transfection, i.e. transfection of non-adherent cells. Using this protocol, we effectively knocked down both high- and low-abundance transcripts in a model of mature brown adipocytes (WT-1) as well as in primary mature mouse brown adipocytes. A functional consequence of the knockdown was confirmed by an attenuated increase in uncoupled respiration (thermogenesis) in response to β-adrenergic stimulation of mature WT-1 brown adipocytes transfected with uncoupling protein 1 siRNA. Efficient gene silencing was also obtained in various mouse and human white adipocyte models (3T3-L1, primary mouse white adipocytes, hMADS) with the ability to undergo "browning." In summary, we report an easy and versatile reverse siRNA transfection protocol to achieve specific silencing of gene expression in various models of mature brown and browning-competent white adipocytes, including primary cells.

Upscaling the diffusion equations in particulate media made of highly conductive particles. I. Theoretical aspects.

PubMed

Vassal, J-P; Orgéas, L; Favier, D; Auriault, J-L; Le Corre, S

2008-01-01

Many analytical and numerical works have been devoted to the prediction of macroscopic effective transport properties in particulate media. Usually, structure and properties of macroscopic balance and constitutive equations are stated a priori. In this paper, the upscaling of the transient diffusion equations in concentrated particulate media with possible particle-particle interfacial barriers, highly conductive particles, poorly conductive matrix, and temperature-dependent physical properties is revisited using the homogenization method based on multiple scale asymptotic expansions. This method uses no a priori assumptions on the physics at the macroscale. For the considered physics and microstructures and depending on the order of magnitude of dimensionless Biot and Fourier numbers, it is shown that some situations cannot be homogenized. For other situations, three different macroscopic models are identified, depending on the quality of particle-particle contacts. They are one-phase media, following the standard heat equation and Fourier's law. Calculations of the effective conductivity tensor and heat capacity are proved to be uncoupled. Linear and steady state continuous localization problems must be solved on representative elementary volumes to compute the effective conductivity tensors for the two first models. For the third model, i.e., for highly resistive contacts, the localization problem becomes simpler and discrete whatever the shape of particles. In paper II [Vassal, Phys. Rev. E 77, 011303 (2008)], diffusion through networks of slender, wavy, entangled, and oriented fibers is considered. Discrete localization problems can then be obtained for all models, as well as semianalytical or fully analytical expressions of the corresponding effective conductivity tensors.

Mitochondrial efficiency and exercise economy following heat stress: a potential role of uncoupling protein 3.

PubMed

Salgado, Roy M; Sheard, Ailish C; Vaughan, Roger A; Parker, Daryl L; Schneider, Suzanne M; Kenefick, Robert W; McCormick, James J; Gannon, Nicholas P; Van Dusseldorp, Trisha A; Kravitz, Len R; Mermier, Christine M

2017-02-01

Heat stress has been reported to reduce uncoupling proteins (UCP) expression, which in turn should improve mitochondrial efficiency. Such an improvement in efficiency may translate to the systemic level as greater exercise economy. However, neither the heat-induced improvement in mitochondrial efficiency (due to decrease in UCP), nor its potential to improve economy has been studied. Determine: (i) if heat stress in vitro lowers UCP3 thereby improving mitochondrial efficiency in C2C12 myocytes; (ii) whether heat acclimation (HA) in vivo improves exercise economy in trained individuals; and (iii) the potential improved economy during exercise at altitude. In vitro, myocytes were heat stressed for 24 h (40°C), followed by measurements of UCP3, mitochondrial uncoupling, and efficiency. In vivo, eight trained males completed: (i) pre-HA testing; (ii) 10 days of HA (40°C, 20% RH); and (iii) post-HA testing. Pre- and posttesting consisted of maximal exercise test and submaximal exercise at two intensities to assess exercise economy at 1600 m (Albuquerque, NM) and 4350 m. Heat-stressed myocytes displayed significantly reduced UCP3 mRNA expression and, mitochondrial uncoupling (77.1 ± 1.2%, P < 0.0001) and improved mitochondrial efficiency (62.9 ± 4.1%, P < 0.0001) compared to control. In humans, at both 1600 m and 4350 m, following HA, submaximal exercise economy did not change at low and moderate exercise intensities. Our findings indicate that while heat-induced reduction in UCP3 improves mitochondrial efficiency in vitro, this is not translated to in vivo improvement of exercise economy at 1600 m or 4350 m. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Impaired Endothelial Repair Capacity of Early Endothelial Progenitor Cells in Hypertensive Patients With Primary Hyperaldosteronemia: Role of 5,6,7,8-Tetrahydrobiopterin Oxidation and Endothelial Nitric Oxide Synthase Uncoupling.

PubMed

Chen, Long; Ding, Mei-Lin; Wu, Fang; He, Wen; Li, Jin; Zhang, Xiao-Yu; Xie, Wen-Li; Duan, Sheng-Zhong; Xia, Wen-Hao; Tao, Jun

2016-02-01

Although hyperaldosteronemia exerts detrimental impacts on vascular endothelium in addition to elevating blood pressure, the effects and molecular mechanisms of hyperaldosteronemia on early endothelial progenitor cell (EPC)-mediated endothelial repair after arterial damage are yet to be determined. The aim of this study was to investigate the endothelial repair capacity of early EPCs from hypertensive patients with primary hyperaldosteronemia (PHA). In vivo endothelial repair capacity of early EPCs from PHAs (n=20), age- and blood pressure-matched essential hypertension patients (n=20), and age-matched healthy subjects (n=20) was evaluated by transplantation into a nude mouse carotid endothelial denudation model. Endothelial function was evaluated by flow-mediated dilation of brachial artery in human subjects. In vivo endothelial repair capacity of early EPCs and flow-mediated dilation were impaired both in PHAs and in essential hypertension patients when compared with age-matched healthy subjects; however, the early EPC in vivo endothelial repair capacity and flow-mediated dilation of PHAs were impaired more severely than essential hypertension patients. Oral spironolactone improved early EPC in vivo endothelial repair capacity and flow-mediated dilation of PHAs. Increased oxidative stress, oxidative 5,6,7,8-tetrahydrobiopterin degradation, endothelial nitric oxide synthase uncoupling and decreased nitric oxide production were found in early EPCs from PHAs. Nicotinamide adenine dinucleotide phosphate oxidase subunit p47(phox) knockdown or 5,6,7,8-tetrahydrobiopterin supplementation attenuated endothelial nitric oxide synthase uncoupling and enhanced in vivo endothelial repair capacity of early EPCs from PHAs. In conclusion, PHAs exhibited more impaired endothelial repair capacity of early EPCs than did essential hypertension patients independent of blood pressure, which was associated with mineralocorticoid receptor-dependent oxidative stress and subsequently 5,6,7,8-tetrahydrobiopterin degradation and endothelial nitric oxide synthase uncoupling. © 2015 American Heart Association, Inc.

Mitochondrial uncoupling reduces exercise capacity despite several skeletal muscle metabolic adaptations.

PubMed

Schlagowski, A I; Singh, F; Charles, A L; Gali Ramamoorthy, T; Favret, F; Piquard, F; Geny, B; Zoll, J

2014-02-15

The effects of mitochondrial uncoupling on skeletal muscle mitochondrial adaptation and maximal exercise capacity are unknown. In this study, rats were divided into a control group (CTL, n = 8) and a group treated with 2,4-dinitrophenol, a mitochondrial uncoupler, for 28 days (DNP, 30 mg·kg(-1)·day(-1) in drinking water, n = 8). The DNP group had a significantly lower body mass (P < 0.05) and a higher resting oxygen uptake (Vo2, P < 0.005). The incremental treadmill test showed that maximal running speed and running economy (P < 0.01) were impaired but that maximal Vo2 (Vo2max) was higher in the DNP-treated rats (P < 0.05). In skinned gastrocnemius fibers, basal respiration (V0) was higher (P < 0.01) in the DNP-treated animals, whereas the acceptor control ratio (ACR, Vmax/V0) was significantly lower (P < 0.05), indicating a reduction in OXPHOS efficiency. In skeletal muscle, DNP activated the mitochondrial biogenesis pathway, as indicated by changes in the mRNA expression of PGC1-α and -β, NRF-1 and -2, and TFAM, and increased the mRNA expression of cytochrome oxidase 1 (P < 0.01). The expression of two mitochondrial proteins (prohibitin and Ndufs 3) was higher after DNP treatment. Mitochondrial fission 1 protein (Fis-1) was increased in the DNP group (P < 0.01), but mitofusin-1 and -2 were unchanged. Histochemical staining for NADH dehydrogenase and succinate dehydrogenase activity in the gastrocnemius muscle revealed an increase in the proportion of oxidative fibers after DNP treatment. Our study shows that mitochondrial uncoupling induces several skeletal muscle adaptations, highlighting the role of mitochondrial coupling as a critical factor for maximal exercise capacities. These results emphasize the importance of investigating the qualitative aspects of mitochondrial function in addition to the amount of mitochondria.

Pyridoxine inhibits endothelial NOS uncoupling induced by oxidized low-density lipoprotein via the PKCα signalling pathway in human umbilical vein endothelial cells

PubMed Central

Xie, Liping; Liu, Zhen; Lu, Hui; Zhang, Wen; Mi, Qiongyu; Li, Xiaozhen; Tang, Yan; Chen, Qi; Ferro, Albert; Ji, Yong

2012-01-01

BACKGROUND AND PURPOSE One key mechanism for endothelial dysfunction is endothelial NOS (eNOS) uncoupling, whereby eNOS generates superoxide (O2•−) rather than NO. We explored the effect of pyridoxine on eNOS uncoupling induced by oxidized low-density lipoprotein (ox-LDL) in human umbilical vein endothelial cells (HUVECs) and the potential molecular mechanism. EXPERIMENTAL APPROACH HUVECs were incubated with ox-LDL with/without pyridoxine, NG-nitro-L-arginine methylester (L-NAME), chelerythrine chloride (CHCI) or apocynin. Endothelial O2•− was measured using lucigenin chemiluminescence, and O2•−-sensitive fluorescent dye dihydroethidium (DHE). NO levels were measured by chemiluminescence, PepTag Assay for non-radioactive detection of PKC activity, depletion of PKCα and p47phox by siRNA silencing and the states of phospho-eNOS Thr495, total-eNOS, phospho-PKCα/βII, total PKC, phospho-PKCα, total PKCα and p47phox were measured by Western blot. KEY RESULTS Ox-LDL significantly increased O2•− production and reduced NO levels released from HUVECs; an effect reversed by eNOS inhibitor, L-NAME. Pyridoxine pretreatment significantly inhibited ox-LDL-induced O2•− generation and preserved NO levels. Pyridoxine also prevented the ox-LDL-induced reduction in phospho-eNOS Thr495 and PKC activity. These protective effects of pyridoxine were abolished by the PKC inhibitor, CHCI, or siRNA silencing of PKCα. However, depletion of p47phox or treatment with the NADPH oxidase inhibitor, apocynin, had no influence on these effects. Also, cytosol p47phox expression was unchanged by the different treatments. CONCLUSIONS AND IMPLICATIONS Pyridoxine mitigated eNOS uncoupling induced by ox-LDL. This protectant effect was related to phosphorylation of eNOS Thr495 stimulated by PKCα, not via NADPH oxidase. These results provide support for the use of pyridoxine in ox-LDL-related vascular endothelial dysfunction. PMID:21797845

Dual role of endothelial nitric oxide synthase in oxidized LDL-induced, p66Shc-mediated oxidative stress in cultured human endothelial cells.

PubMed

Shi, Yi; Lüscher, Thomas F; Camici, Giovanni G

2014-01-01

The aging gene p66Shc, is an important mediator of oxidative stress-induced vascular dysfunction and disease. In cultured human aortic endothelial cells (HAEC), p66Shc deletion increases endothelial nitric oxide synthase (eNOS) expression and nitric oxide (NO) bioavailability via protein kinase B. However, the putative role of the NO pathway on p66Shc activation remains unclear. This study was designed to elucidate the regulatory role of the eNOS/NO pathway on p66Shc activation. Incubation of HAEC with oxidized low density lipoprotein (oxLDL) led to phosphorylation of p66Shc at Ser-36, resulting in an enhanced production of superoxide anion (O2-). In the absence of oxLDL, inhibition of eNOS by small interfering RNA or L-NAME, induced p66Shc phosphorylation, suggesting that basal NO production inhibits O2- production. oxLDL-induced, p66Shc-mediated O2- was prevented by eNOS inhibition, suggesting that when cells are stimulated with oxLDL eNOS is a source of reactive oxygen species. Endogenous or exogenous NO donors, prevented p66Shc activation and reduced O2- production. Treatment with tetrahydrobiopterin, an eNOS cofactor, restored eNOS uncoupling, prevented p66Shc activation, and reduced O2- generation. However, late treatment with tetrahydropterin did not yield the same result suggesting that eNOS uncoupling is the primary source of reactive oxygen species. The present study reports that in primary cultured HAEC treated with oxLDL, p66Shc-mediated oxidative stress is derived from eNOS uncoupling. This finding contributes novel information on the mechanisms of p66Shc activation and its dual interaction with eNOS underscoring the importance eNOS uncoupling as a putative antioxidant therapeutical target in endothelial dysfunction as observed in cardiovascular disease.

Numerical Investigation of Desulfurization Kinetics in Gas-Stirred Ladles by a Quick Modeling Analysis Approach

NASA Astrophysics Data System (ADS)

Cao, Qing; Nastac, Laurentiu; Pitts-Baggett, April; Yu, Qiulin

2018-03-01

A quick modeling analysis approach for predicting the slag-steel reaction and desulfurization kinetics in argon gas-stirred ladles has been developed in this study. The model consists of two uncoupled components: (i) a computational fluid dynamics (CFD) model for predicting the fluid flow and the characteristics of slag-steel interface, and (ii) a multicomponent reaction kinetics model for calculating the desulfurization evolution. The steel-slag interfacial area and mass transfer coefficients predicted by the CFD simulation are used as the processing data for the reaction model. Since the desulfurization predictions are uncoupled from the CFD simulation, the computational time of this uncoupled predictive approach is decreased by at least 100 times for each case study when compared with the CFD-reaction kinetics fully coupled model. The uncoupled modeling approach was validated by comparing the evolution of steel and slag compositions with the experimentally measured data during ladle metallurgical furnace (LMF) processing at Nucor Steel Tuscaloosa, Inc. Then, the validated approach was applied to investigate the effects of the initial steel and slag compositions, as well as different types of additions during the refining process on the desulfurization efficiency. The results revealed that the sulfur distribution ratio and the desulfurization reaction can be promoted by making Al and CaO additions during the refining process. It was also shown that by increasing the initial Al content in liquid steel, both Al oxidation and desulfurization rates rapidly increase. In addition, it was found that the variation of the initial Si content in steel has no significant influence on the desulfurization rate. Lastly, if the initial CaO content in slag is increased or the initial Al2O3 content is decreased in the fluid-slag compositional range, the desulfurization rate can be improved significantly during the LMF process.

Desipramine prevents cardiac gap junction uncoupling.

PubMed

Jozwiak, Joanna; Dietze, Anna; Grover, Rajiv; Savtschenko, Alex; Etz, Christian; Mohr, Friedrich W; Dhein, Stefan

2012-11-01

Uncoupling of cardiac gap junction channels is an important arrhythmogenic mechanism in ischemia/reperfusion. Antiarrhythmic peptide AAP10 (H-Gly-Ala-Gly-Hyp-Pro-Tyr-CONH(2)) has been shown to prevent acidosis-induced uncoupling and ischemia-related increase in dispersion. Previous structure-effect investigations and subsequent computer modeling studies indicated that the tricyclic antidepressant desipramine may exert similar effects as AAP10. We assessed the binding of (14)C-AAP10 to membranes of rabbit cardiac ventricles and its displacement with desipramine in a classical radioligand binding and competition study. Gap junction currents were measured between isolated pairs of human atrial cardiomyocytes under normal and acidotic (pH 6.3) conditions with or without 1 μmol/l desipramine using dual whole-cell voltage clamp. The effect of 1 μmol/l desipramine was assessed in isolated rabbit hearts (Langendorff technique) undergoing local ischemia by coronary occlusion with 256-channel electrophysiological mapping and subsequent analysis of connexin43 (Cx43) expression, phosphorylation (Western blot), and subcellular localization (immunohistology). We found saturable (14)C-AAP10 binding to cardiac membranes (K (D), 0.29 ± 0.11 nmol/l; B (max), 42.5 ± 7.2 pmol/mg) which could be displaced by desipramine with a K (D.High) = 0.14 μmol/l and a K (D.Low) = 22 μmol/l. Acidosis reduced the gap junction conductance in human cardiomyocyte pairs from 24.1 ± 4.7 to 11.5 ± 2.5 nS, which could be significantly reversed by desipramine (26.6 ± 4.8 nS). In isolated hearts, ischemia resulted in significantly increased dispersion of activation-recovery intervals, loss of membrane Cx43, and dephosphorylation of Cx43, which all could be prevented by desipramine. Desipramine seems to prevent the uncoupling of cardiac gap junctions and ischemia-related increase in dispersion.

Numerical Investigation of Desulfurization Kinetics in Gas-Stirred Ladles by a Quick Modeling Analysis Approach

NASA Astrophysics Data System (ADS)

Cao, Qing; Nastac, Laurentiu; Pitts-Baggett, April; Yu, Qiulin

2018-06-01

A quick modeling analysis approach for predicting the slag-steel reaction and desulfurization kinetics in argon gas-stirred ladles has been developed in this study. The model consists of two uncoupled components: (i) a computational fluid dynamics (CFD) model for predicting the fluid flow and the characteristics of slag-steel interface, and (ii) a multicomponent reaction kinetics model for calculating the desulfurization evolution. The steel-slag interfacial area and mass transfer coefficients predicted by the CFD simulation are used as the processing data for the reaction model. Since the desulfurization predictions are uncoupled from the CFD simulation, the computational time of this uncoupled predictive approach is decreased by at least 100 times for each case study when compared with the CFD-reaction kinetics fully coupled model. The uncoupled modeling approach was validated by comparing the evolution of steel and slag compositions with the experimentally measured data during ladle metallurgical furnace (LMF) processing at Nucor Steel Tuscaloosa, Inc. Then, the validated approach was applied to investigate the effects of the initial steel and slag compositions, as well as different types of additions during the refining process on the desulfurization efficiency. The results revealed that the sulfur distribution ratio and the desulfurization reaction can be promoted by making Al and CaO additions during the refining process. It was also shown that by increasing the initial Al content in liquid steel, both Al oxidation and desulfurization rates rapidly increase. In addition, it was found that the variation of the initial Si content in steel has no significant influence on the desulfurization rate. Lastly, if the initial CaO content in slag is increased or the initial Al2O3 content is decreased in the fluid-slag compositional range, the desulfurization rate can be improved significantly during the LMF process.

Real‐time monitoring of specific oxygen uptake rates of embryonic stem cells in a microfluidic cell culture device

PubMed Central

Super, Alexandre; Jaccard, Nicolas; Cardoso Marques, Marco Paulo; Macown, Rhys Jarred; Griffin, Lewis Donald; Veraitch, Farlan Singh

2016-01-01

Abstract Oxygen plays a key role in stem cell biology as a signaling molecule and as an indicator of cell energy metabolism. Quantification of cellular oxygen kinetics, i.e. the determination of specific oxygen uptake rates (sOURs), is routinely used to understand metabolic shifts. However current methods to determine sOUR in adherent cell cultures rely on cell sampling, which impacts on cellular phenotype. We present real‐time monitoring of cell growth from phase contrast microscopy images, and of respiration using optical sensors for dissolved oxygen. Time‐course data for bulk and peri‐cellular oxygen concentrations obtained for Chinese hamster ovary (CHO) and mouse embryonic stem cell (mESCs) cultures successfully demonstrated this non‐invasive and label‐free approach. Additionally, we confirmed non‐invasive detection of cellular responses to rapidly changing culture conditions by exposing the cells to mitochondrial inhibiting and uncoupling agents. For the CHO and mESCs, sOUR values between 8 and 60 amol cell−1 s−1, and 5 and 35 amol cell−1 s−1 were obtained, respectively. These values compare favorably with literature data. The capability to monitor oxygen tensions, cell growth, and sOUR, of adherent stem cell cultures, non‐invasively and in real time, will be of significant benefit for future studies in stem cell biology and stem cell‐based therapies. PMID:27214658

Application of an Uncoupled Elastic-plastic-creep Constitutive Model to Metals at High Temperature

NASA Technical Reports Server (NTRS)

Haisler, W. E.

1983-01-01

A uniaxial, uncoupled constitutive model to predict the response of thermal and rate dependent elastic-plastic material behavior is presented. The model is based on an incremental classicial plasticity theory extended to account for thermal, creep, and transient temperature conditions. Revisions to he combined hardening rule of the theory allow for better representation of cyclic phenomenon including the high rate of strain hardening upon cyclic reyield and cyclic saturation. An alternative approach is taken to model the rate dependent inelastic deformation which utilizes hysteresis loops and stress relaxation test data at various temperatures. The model is evaluated and compared to experiments which involve various thermal and mechanical load histories on 5086 aluminum alloy, 304 stainless steel and Hastelloy-X.

Study on Dynamic Alignment Technology of COIL Resonator

NASA Astrophysics Data System (ADS)

Xiong, M. D.; Zou, X. J.; Guo, J. H.; Jia, S. N.; Zhang2, Z. B.

2006-10-01

The performance of great power chemical oxygen-iodine laser (COIL) beam is decided mostly by resonator mirror maladjustment and environment vibration. To improve the performance of light beam, an auto-alignment device is used in COIL resonator, the device can keep COIL resonator collimating by adjusting the optical components of resonator. So the coupling model of COIL resonator is present. The multivariable self study fuzzy uncoupling arithmetic and six-dimensional micro drive technology are used to design a six-input-three-output uncoupling controller, resulting in the realization of the high precision dynamic alignment. The experiments indicate that the collimating range of this system is 8 mrad, precision is 5 urad and frequency response is 20Hz, which meet the demand of resonator alignment system.

A high-throughput screen for mitochondrial function reveals known and novel mitochondrial toxicants in a library of environmental agents

PubMed Central

Datta, Sandipan; Sahdeo, Sunil; Gray, Jennifer A.; Morriseau, Christophe; Hammock, Bruce D.; Cortopassi, Gino

2016-01-01

Mitochondrial toxicity is emerging as a major mechanism underlying serious human health consequences. This work performs a high-throughput screen (HTS) of 176 environmental chemicals for mitochondrial toxicity utilizing a previously reported biosensor platform. This established HTS confirmed known mitochondrial toxins and identified novel mitotochondrial uncouplers such as 2, 2′-Methylenebis(4-chlorophenol) and pentachlorophenol. It also identified a mitochondrial ‘structure activity relationship’ (SAR) in the sense that multiple environmental chlorophenols are mitochondrial inhibitors and uncouplers. This study demonstrates proof-of-concept that a mitochondrial HTS assay detects known and novel environmental mitotoxicants, and could be used to quickly evaluate human health risks from mitotoxicants in the environment. PMID:27717841

Plant uncoupling mitochondrial proteins.

PubMed

Vercesi, Aníbal Eugênio; Borecký, Jiri; Maia, Ivan de Godoy; Arruda, Paulo; Cuccovia, Iolanda Midea; Chaimovich, Hernan

2006-01-01

Uncoupling proteins (UCPs) are membrane proteins that mediate purine nucleotide-sensitive free fatty acid-activated H(+) flux through the inner mitochondrial membrane. After the discovery of UCP in higher plants in 1995, it was acknowledged that these proteins are widely distributed in eukaryotic organisms. The widespread presence of UCPs in eukaryotes implies that these proteins may have functions other than thermogenesis. In this review, we describe the current knowledge of plant UCPs, including their discovery, biochemical properties, distribution, gene family, gene expression profiles, regulation of gene expression, and evolutionary aspects. Expression analyses and functional studies on the plant UCPs under normal and stressful conditions suggest that UCPs regulate energy metabolism in the cellular responses to stress through regulation of the electrochemical proton potential (Deltamu(H)+) and production of reactive oxygen species.

Modified spin-wave theory with ordering vector optimization: spatially anisotropic triangular lattice and J1J2J3 model with Heisenberg interactions

NASA Astrophysics Data System (ADS)

Hauke, Philipp; Roscilde, Tommaso; Murg, Valentin; Cirac, J. Ignacio; Schmied, Roman

2011-07-01

We study the ground-state phases of the S=1/2 Heisenberg quantum antiferromagnet on the spatially anisotropic triangular lattice (SATL) and on the square lattice with up to next-next-nearest-neighbor coupling (the J1J2J3 model), making use of Takahashi's modified spin-wave (MSW) theory supplemented by ordering vector optimization. We compare the MSW results with exact diagonalization and projected-entangled-pair-states calculations, demonstrating their qualitative and quantitative reliability. We find that the MSW theory correctly accounts for strong quantum effects on the ordering vector of the magnetic phases of the models under investigation: in particular, collinear magnetic order is promoted at the expense of non-collinear (spiral) order, and several spiral states that are stable at the classical level disappear from the quantum phase diagram. Moreover, collinear states and non-collinear ones are never connected continuously, but they are separated by parameter regions in which the MSW theory breaks down, signaling the possible appearance of a non-magnetic ground state. In the case of the SATL, a large breakdown region appears also for weak couplings between the chains composing the lattice, suggesting the possible occurrence of a large non-magnetic region continuously connected with the spin-liquid state of the uncoupled chains. This shows that the MSW theory is—despite its apparent simplicity—a versatile tool for finding candidate regions in the case of spin-liquid phases, which are among prime targets for relevant quantum simulations.

Collocated electrodynamic FDTD schemes using overlapping Yee grids and higher-order Hodge duals

NASA Astrophysics Data System (ADS)

Deimert, C.; Potter, M. E.; Okoniewski, M.

2016-12-01

The collocated Lebedev grid has previously been proposed as an alternative to the Yee grid for electromagnetic finite-difference time-domain (FDTD) simulations. While it performs better in anisotropic media, it performs poorly in isotropic media because it is equivalent to four overlapping, uncoupled Yee grids. We propose to couple the four Yee grids and fix the Lebedev method using discrete exterior calculus (DEC) with higher-order Hodge duals. We find that higher-order Hodge duals do improve the performance of the Lebedev grid, but they also improve the Yee grid by a similar amount. The effectiveness of coupling overlapping Yee grids with a higher-order Hodge dual is thus questionable. However, the theoretical foundations developed to derive these methods may be of interest in other problems.

Internal desynchronization in a model of night-work by forced activity in rats.

PubMed

Salgado-Delgado, R; Angeles-Castellanos, M; Buijs, M R; Escobar, C

2008-06-26

Individuals engaged in shift- or night-work show disturbed diurnal rhythms, out of phase with temporal signals associated to the light/dark (LD) cycle, resulting in internal desynchronization. The mechanisms underlying internal desynchrony have been mainly investigated in experimental animals with protocols that induce phase shifts of the LD cycle and thus modify the activity of the suprachiasmatic nucleus (SCN). In this study we developed an animal model of night-work in which the light-day cycle remained stable and rats were required to be active in a rotating wheel for 8 h daily during their sleeping phase (W-SP). This group was compared with rats that were working in the wheel during their activity phase (W-AP) and with undisturbed rats (C). We provide evidence that forced activity during the sleeping phase (W-SP group) alters not only activity, but also the temporal pattern of food intake. In consequence W-SP rats showed a loss of glucose rhythmicity and a reversed rhythm of triacylglycerols. In contrast W-AP rats did not show such changes and exhibited metabolic rhythms similar to those of the controls. The three groups exhibited the nocturnal corticosterone increase, in addition the W-SP and W-AP groups showed increase of plasma corticosterone associated with the start of the working session. Forced activity during the sleep phase did not modify SCN activity characterized by the temporal patterns of PER1 and PER2 proteins, which remained in phase with the LD cycle. These observations indicate that a working regimen during the sleeping period elicits internal desynchronization in which activity combined with feeding uncouples metabolic functions from the biological clock which remains fixed to the LD cycle. The present data suggest that in the night worker the combination of work and eating during working hours may be the cause of internal desynchronization.

The nonlinear dynamics of a spacecraft coupled to the vibration of a contained fluid

NASA Technical Reports Server (NTRS)

Peterson, Lee D.; Crawley, Edward F.; Hansman, R. John

1988-01-01

The dynamics of a linear spacecraft mode coupled to a nonlinear low gravity slosh of a fluid in a cylindrical tank is investigated. Coupled, nonlinear equations of motion for the fluid-spacecraft dynamics are derived through an assumed mode Lagrangian method. Unlike linear fluid slosh models, this nonlinear slosh model retains two fundamental slosh modes and three secondary modes. An approximate perturbation solution of the equations of motion indicates that the nonlinear coupled system response involves fluid-spacecraft modal resonances not predicted by either a linear, or a nonlinear, uncoupled slosh analysis. Experimental results substantiate the analytical predictions.

Nitrates and bone turnover (NABT) - trial to select the best nitrate preparation: study protocol for a randomized controlled trial

PubMed Central

2013-01-01

Background Organic nitrates uncouple bone turnover, improve bone mineral density, and improve trabecular and cortical components of bone. These changes in turnover, strength and geometry may translate into an important reduction in fractures. However, before proceeding with a large fracture trial, there is a need to identify the nitrate formulation that has both the greatest efficacy (with regards to bone turnover markers) and gives the fewest headaches. Ascertaining which nitrate formulation this may be is the purpose of the current study. Methods and design This will be an open-label randomized, controlled trial conducted at Women’s College Hospital comparing five formulations of nitrates for their effects on bone turnover markers and headache. We will recruit postmenopausal women age 50 years or older with no contraindications to nitroglycerin. Our trial will consist of a run-in phase and a treatment phase. We will enroll 420 women in the run-in phase, each to receive all of the 5 potential treatments in random order for 2 days, each with a 2-day washout period between treatments. Those who tolerate all formulations will enter the 12-week treatment phase and be randomly assigned to one of five groups: 0.3 mg sublingual nitroglycerin tablet, 0.6 mg of the sublingual tablet, a 20 mg tablet of isosorbide mononitrate, a 160 mg nitroglycerin transdermal patch (used for 8 h), and 15 mg of nitroglycerin ointment as used in a previous trial by our group. We will continue enrolment until we have randomized 210 women or 35 women per group. Concentrations of bone formation (bone-specific alkaline phosphatase and procollagen type I N-terminal propeptide) and bone resorption (C-telopeptides of collagen crosslinks and N-terminal crosslinks of collagen) agents will be measured in samples taken at study entry (the start of the run in phase) and 12 weeks. Subjects will record the frequency and severity of headaches daily during the run-in phase and then monthly after that. We will use the ‘multiple comparisons with the best’ approach for data analyses, as this strategy allows practical considerations of ease of use and tolerability to guide selection of the preparation for future studies. Discussion Data from this protocol will be used to develop a randomized, controlled trial of nitrates to prevent osteoporotic fractures. Trial registration ClinicalTrials.gov Identifier: NCT01387672. Controlled-Trials.com: ISRCTN08860742. PMID:24010992

Uncoupling proteins and sleep deprivation.

PubMed

Cirelli, C; Tononi, G

2004-07-01

In both humans and animals sleep deprivation (SD) produces an increase in food intake and in energy expenditure (EE). The increase in EE is a core element of the SD syndrome and, in rats, is negatively correlated with survival rate. However, the mechanisms involved are not understood. A large component of resting EE is accounted for by the mitochondrial proton leak, which is mediated by uncoupling proteins (UCPs). We measured UCP2, UCP3, and UCP5 mRNA levels in rats during the spontaneous sleep/waking cycle and after short (8 hours) and long (7 days) SD. During spontaneous sleep and waking there was no change in the level of mitochondrial uncoupling as measured by UCPs expression, either in the brain or in peripheral tissues. During SD, by contrast, UCP3 expression in skeletal muscle was elevated, but the increase was similar, compared to sleep, after both short-term and long-term SD. UCP2 expression, on the other hand, was strongly increased in the liver and skeletal muscle of long-term sleep deprived animals and much less so, or not at all, in yoked controls or in rats that lost only 8 hours of sleep. Since the skeletal muscle is the largest tissue in the body, an elevated muscular expression of UCP2 is likely to affect the overall resting EE and may thus contribute to its increase after SD.

Glutathionylation state of uncoupling protein-2 and the control of glucose-stimulated insulin secretion.

PubMed

Mailloux, Ryan J; Fu, Accalia; Robson-Doucette, Christine; Allister, Emma M; Wheeler, Michael B; Screaton, Robert; Harper, Mary-Ellen

2012-11-16

The role of reactive oxygen species (ROS) in glucose-stimulated insulin release remains controversial because ROS have been shown to both amplify and impede insulin release. In regard to preventing insulin release, ROS activates uncoupling protein-2 (UCP2), a mitochondrial inner membrane protein that negatively regulates glucose-stimulated insulin secretion (GSIS) by uncoupling oxidative phosphorylation. With our recent discovery that the UCP2-mediated proton leak is modulated by reversible glutathionylation, a process responsive to small changes in ROS levels, we resolved to determine whether glutathionylation is required for UCP2 regulation of GSIS. Using Min6 cells and pancreatic islets, we demonstrate that induction of glutathionylation not only deactivates UCP2-mediated proton leak but also enhances GSIS. Conversely, an increase in mitochondrial matrix ROS was found to deglutathionylate and activate UCP2 leak and impede GSIS. Glucose metabolism also decreased the total amount of cellular glutathionylated proteins and increased the cellular glutathione redox ratio (GSH/GSSG). Intriguingly, the provision of extracellular ROS (H(2)O(2), 10 μM) amplified GSIS and also activated UCP2. Collectively, our findings indicate that the glutathionylation status of UCP2 contributes to the regulation of GSIS, and different cellular sites and inducers of ROS can have opposing effects on GSIS, perhaps explaining some of the controversy surrounding the role of ROS in GSIS.

Astrocyte uncoupling as a cause of human temporal lobe epilepsy

PubMed Central

Bedner, Peter; Dupper, Alexander; Hüttmann, Kerstin; Müller, Julia; Herde, Michel K.; Dublin, Pavel; Deshpande, Tushar; Schramm, Johannes; Häussler, Ute; Haas, Carola A.; Henneberger, Christian; Theis, Martin

2015-01-01

Glial cells are now recognized as active communication partners in the central nervous system, and this new perspective has rekindled the question of their role in pathology. In the present study we analysed functional properties of astrocytes in hippocampal specimens from patients with mesial temporal lobe epilepsy without (n = 44) and with sclerosis (n = 75) combining patch clamp recording, K+ concentration analysis, electroencephalography/video-monitoring, and fate mapping analysis. We found that the hippocampus of patients with mesial temporal lobe epilepsy with sclerosis is completely devoid of bona fide astrocytes and gap junction coupling, whereas coupled astrocytes were abundantly present in non-sclerotic specimens. To decide whether these glial changes represent cause or effect of mesial temporal lobe epilepsy with sclerosis, we developed a mouse model that reproduced key features of human mesial temporal lobe epilepsy with sclerosis. In this model, uncoupling impaired K+ buffering and temporally preceded apoptotic neuronal death and the generation of spontaneous seizures. Uncoupling was induced through intraperitoneal injection of lipopolysaccharide, prevented in Toll-like receptor4 knockout mice and reproduced in situ through acute cytokine or lipopolysaccharide incubation. Fate mapping confirmed that in the course of mesial temporal lobe epilepsy with sclerosis, astrocytes acquire an atypical functional phenotype and lose coupling. These data suggest that astrocyte dysfunction might be a prime cause of mesial temporal lobe epilepsy with sclerosis and identify novel targets for anti-epileptogenic therapeutic intervention. PMID:25765328

Uncoupling the Trade-Off between Somatic Proteostasis and Reproduction in Caenorhabditis elegans Models of Polyglutamine Diseases

PubMed Central

Shemesh, Netta; Shai, Nadav; Meshnik, Lana; Katalan, Rotem; Ben-Zvi, Anat

2017-01-01

Caenorhabditis elegans somatic protein homeostasis (proteostasis) is actively remodeled at the onset of reproduction. This proteostatic collapse is regulated cell-nonautonomously by signals from the reproductive system that transmit the commitment to reproduction to somatic cells. Here, we asked whether the link between the reproductive system and somatic proteostasis could be uncoupled by activating downstream effectors in the gonadal longevity cascade. Specifically, we examined whether over-expression of lipl-4 (lipl-4(oe)), a target gene of the gonadal longevity pathway, or increase in arachidonic acid (AA) levels, associated with lipl-4(oe), modulated proteostasis and reproduction. We found that lipl-4(oe) rescued somatic proteostasis and postponed the onset of aggregation and toxicity in C. elegans models of polyglutamine (polyQ) diseases. However, lipl-4(oe) also disrupted fatty acid transport into developing oocytes and reduced reproductive success. In contrast, diet supplementation of AA recapitulated lipl-4(oe)-mediated proteostasis enhancement in wild type animals but did not affect the reproductive system. Thus, the gonadal longevity pathway mediates a trade-off between somatic maintenance and reproduction, in part by regulating the expression of genes, such as lipl-4, with inverse effects on somatic maintenance and reproduction. We propose that AA could uncouple such germline to soma crosstalk, with beneficial implications protein misfolding diseases. PMID:28503130

Liver-enriched transcription factors uncoupled from expression of hepatic functions in hepatoma cell lines.

PubMed Central

Chaya, D; Fougère-Deschatrette, C; Weiss, M C

1997-01-01

Among the liver-enriched transcription factors identified to date, only expression of hepatocyte nuclear factor 4 (HNF4) and hepatocyte nuclear factor 1 (HNF1) is in strict correlation with hepatic differentiation in cultured rat hepatoma cells. Indeed, differentiated hepatoma cells that stably express an extensive set of adult hepatic functions express liver-enriched transcription factors, while dedifferentiated cells that have lost expression of all these hepatic functions no longer express HNF4 and HNF1. We describe a new heritable phenotype, designated as uncoupled, in which there is a spontaneous dissociation between the expression of these transcription factors and that of the hepatic functions. Cells presenting this phenotype, isolated from differentiated hepatoma cells, cease to accumulate all transcripts coding for hepatic functions but nevertheless maintain expression of HNF4 and HNF1. Transitory transfection experiments indicate that these two factors present in these cells have transcriptional activity similar to that of differentiated hepatoma cells. Characterization of the appropriate intertypic cell hybrids demonstrates that this new phenotype is recessive to the dedifferentiated state and fails to be complemented by differentiated cells. These results indicate the existence of mechanisms that inhibit transcription of genes coding for hepatocyte functions in spite of the presence of functional HNF4 and HNF1. Cells of the uncoupled phenotype present certain properties of oval cells described for pathological states of the liver. PMID:9343392

Liver-enriched transcription factors uncoupled from expression of hepatic functions in hepatoma cell lines.

PubMed

Chaya, D; Fougère-Deschatrette, C; Weiss, M C

1997-11-01

Among the liver-enriched transcription factors identified to date, only expression of hepatocyte nuclear factor 4 (HNF4) and hepatocyte nuclear factor 1 (HNF1) is in strict correlation with hepatic differentiation in cultured rat hepatoma cells. Indeed, differentiated hepatoma cells that stably express an extensive set of adult hepatic functions express liver-enriched transcription factors, while dedifferentiated cells that have lost expression of all these hepatic functions no longer express HNF4 and HNF1. We describe a new heritable phenotype, designated as uncoupled, in which there is a spontaneous dissociation between the expression of these transcription factors and that of the hepatic functions. Cells presenting this phenotype, isolated from differentiated hepatoma cells, cease to accumulate all transcripts coding for hepatic functions but nevertheless maintain expression of HNF4 and HNF1. Transitory transfection experiments indicate that these two factors present in these cells have transcriptional activity similar to that of differentiated hepatoma cells. Characterization of the appropriate intertypic cell hybrids demonstrates that this new phenotype is recessive to the dedifferentiated state and fails to be complemented by differentiated cells. These results indicate the existence of mechanisms that inhibit transcription of genes coding for hepatocyte functions in spite of the presence of functional HNF4 and HNF1. Cells of the uncoupled phenotype present certain properties of oval cells described for pathological states of the liver.

Single nucleotide polymorphisms linked to mitochondrial uncoupling protein genes UCP2 and UCP3 affect mitochondrial metabolism and healthy aging in female nonagenarians.

PubMed

Kim, Sangkyu; Myers, Leann; Ravussin, Eric; Cherry, Katie E; Jazwinski, S Michal

2016-08-01

Energy expenditure decreases with age, but in the oldest-old, energy demand for maintenance of body functions increases with declining health. Uncoupling proteins have profound impact on mitochondrial metabolic processes; therefore, we focused attention on mitochondrial uncoupling protein genes. Alongside resting metabolic rate (RMR), two SNPs in the promoter region of UCP2 were associated with healthy aging. These SNPs mark potential binding sites for several transcription factors; thus, they may affect expression of the gene. A third SNP in the 3'-UTR of UCP3 interacted with RMR. This UCP3 SNP is known to impact UCP3 expression in tissue culture cells, and it has been associated with body weight and mitochondrial energy metabolism. The significant main effects of the UCP2 SNPs and the interaction effect of the UCP3 SNP were also observed after controlling for fat-free mass (FFM) and physical-activity related energy consumption. The association of UCP2/3 with healthy aging was not found in males. Thus, our study provides evidence that the genetic risk factors for healthy aging differ in males and females, as expected from the differences in the phenotypes associated with healthy aging between the two sexes. It also has implications for how mitochondrial function changes during aging.

Uncoupling protein and ATP/ADP carrier increase mitochondrial proton conductance after cold adaptation of king penguins.

PubMed

Talbot, Darren A; Duchamp, Claude; Rey, Benjamin; Hanuise, Nicolas; Rouanet, Jean Louis; Sibille, Brigitte; Brand, Martin D

2004-07-01

Juvenile king penguins develop adaptive thermogenesis after repeated immersion in cold water. However, the mechanisms of such metabolic adaptation in birds are unknown, as they lack brown adipose tissue and uncoupling protein-1 (UCP1), which mediate adaptive non-shivering thermogenesis in mammals. We used three different groups of juvenile king penguins to investigate the mitochondrial basis of avian adaptive thermogenesis in vitro. Skeletal muscle mitochondria isolated from penguins that had never been immersed in cold water showed no superoxide-stimulated proton conductance, indicating no functional avian UCP. Skeletal muscle mitochondria from penguins that had been either experimentally immersed or naturally adapted to cold water did possess functional avian UCP, demonstrated by a superoxide-stimulated, GDP-inhibitable proton conductance across their inner membrane. This was associated with a markedly greater abundance of avian UCP mRNA. In the presence (but not the absence) of fatty acids, these mitochondria also showed a greater adenine nucleotide translocase-catalysed proton conductance than those from never-immersed penguins. This was due to an increase in the amount of adenine nucleotide translocase. Therefore, adaptive thermogenesis in juvenile king penguins is linked to two separate mechanisms of uncoupling of oxidative phosphorylation in skeletal muscle mitochondria: increased proton transport activity of avian UCP (dependent on superoxide and inhibited by GDP) and increased proton transport activity of the adenine nucleotide translocase (dependent on fatty acids and inhibited by carboxyatractylate).

Glutathionylation State of Uncoupling Protein-2 and the Control of Glucose-stimulated Insulin Secretion*

PubMed Central

Mailloux, Ryan J.; Fu, Accalia; Robson-Doucette, Christine; Allister, Emma M.; Wheeler, Michael B.; Screaton, Robert; Harper, Mary-Ellen

2012-01-01

The role of reactive oxygen species (ROS) in glucose-stimulated insulin release remains controversial because ROS have been shown to both amplify and impede insulin release. In regard to preventing insulin release, ROS activates uncoupling protein-2 (UCP2), a mitochondrial inner membrane protein that negatively regulates glucose-stimulated insulin secretion (GSIS) by uncoupling oxidative phosphorylation. With our recent discovery that the UCP2-mediated proton leak is modulated by reversible glutathionylation, a process responsive to small changes in ROS levels, we resolved to determine whether glutathionylation is required for UCP2 regulation of GSIS. Using Min6 cells and pancreatic islets, we demonstrate that induction of glutathionylation not only deactivates UCP2-mediated proton leak but also enhances GSIS. Conversely, an increase in mitochondrial matrix ROS was found to deglutathionylate and activate UCP2 leak and impede GSIS. Glucose metabolism also decreased the total amount of cellular glutathionylated proteins and increased the cellular glutathione redox ratio (GSH/GSSG). Intriguingly, the provision of extracellular ROS (H2O2, 10 μm) amplified GSIS and also activated UCP2. Collectively, our findings indicate that the glutathionylation status of UCP2 contributes to the regulation of GSIS, and different cellular sites and inducers of ROS can have opposing effects on GSIS, perhaps explaining some of the controversy surrounding the role of ROS in GSIS. PMID:23035124

Single nucleotide polymorphisms linked to mitochondrial uncoupling protein genes UCP2 and UCP3 affect mitochondrial metabolism and healthy aging in female nonagenarians

PubMed Central

Kim, Sangkyu; Myers, Leann; Ravussin, Eric; Cherry, Katie E.; Jazwinski, S. Michal

2016-01-01

Energy expenditure decreases with age, but in the oldest-old, energy demand for maintenance of body functions increases with declining health. Uncoupling proteins have profound impact on mitochondrial metabolic processes; therefore, we focused attention on mitochondrial uncoupling protein genes. Alongside resting metabolic rate (RMR), two SNPs in the promoter region of UCP2 were associated with healthy aging. These SNPs mark potential binding sites for several transcription factors; thus, they may affect expression of the gene. A third SNP in the 3′-UTR of UCP3 interacted with RMR. This UCP3 SNP is known to impact UCP3 expression in tissue culture cells, and it has been associated with body weight and mitochondrial energy metabolism. The significant main effects of the UCP2 SNPs and the interaction effect of the UCP3 SNP were also observed after controlling for fat-free mass (FFM) and physical-activity related energy consumption. The association of UCP2/3 with healthy aging was not found in males. Thus, our study provides evidence that the genetic risk factors for healthy aging differ in males and females, as expected from the differences in the phenotypes associated with healthy aging between the two sexes. It also has implications for how mitochondrial function changes during aging. PMID:26965008

Synthesis and recycling of tetrahydrobiopterin in endothelial function and vascular disease.

PubMed

Crabtree, Mark J; Channon, Keith M

2011-08-01

Nitric oxide, generated by the nitric oxide synthase (NOS) enzymes, plays pivotal roles in cardiovascular homeostasis and in the pathogenesis of cardiovascular disease. The NOS cofactor, tetrahydrobiopterin (BH4), is an important regulator of NOS function, since BH4 is required to maintain enzymatic coupling of L-arginine oxidation, to produce NO. Loss or oxidation of BH4 to 7,8-dihydrobiopterin (BH2) is associated with NOS uncoupling, resulting in the production of superoxide rather than NO. In addition to key roles in folate metabolism, dihydrofolate reductase (DHFR) can 'recycle' BH2, and thus regenerate BH4. It is therefore likely that net BH4 cellular bioavailability reflects the balance between de novo BH4 synthesis, loss of BH4 by oxidation to BH2, and the regeneration of BH4 by DHFR. Recent studies have implicated BH4 recycling in the direct regulation of eNOS uncoupling, showing that inhibition of BH4 recycling using DHFR-specific siRNA and methotrexate treatment leads to eNOS uncoupling in endothelial cells and the hph-1 mouse model of BH4 deficiency, even in the absence of oxidative stress. These studies indicate that not only BH4 level, but the recycling pathways regulating BH4 bioavailability represent potential therapeutic targets and will be discussed in this review. Copyright © 2011 Elsevier Inc. All rights reserved.

Apparatus and method for solid fuel chemical looping combustion

DOEpatents

Siriwardane, Ranjani V; Weber, Justin M

2015-04-14

The disclosure provides an apparatus and method utilizing fuel reactor comprised of a fuel section, an oxygen carrier section, and a porous divider separating the fuel section and the oxygen carrier section. The porous divider allows fluid communication between the fuel section and the oxygen carrier section while preventing the migration of solids of a particular size. Maintaining particle segregation between the oxygen carrier section and the fuel section during solid fuel gasification and combustion processes allows gases generated in either section to participate in necessary reactions while greatly mitigating issues associated with mixture of the oxygen carrier with char or ash products. The apparatus and method may be utilized with an oxygen uncoupling oxygen carrier such as CuO, Mn.sub.3O.sub.4, or Co.sub.3O.sub.4, or utilized with a CO/H.sub.2 reducing oxygen carrier such as Fe.sub.2O.sub.3.

Mitochondrial proticity and ROS signaling: lessons from the uncoupling proteins.

PubMed

Mailloux, Ryan J; Harper, Mary-Ellen

2012-09-01

Fifty years since Peter Mitchell proposed the theory of chemiosmosis, the transformation of cellular redox potential into ATP synthetic capacity is still a widely recognized function of mitochondria. Mitchell used the term 'proticity' to describe the force and flow of the proton circuit across the inner membrane. When the proton gradient is coupled to ATP synthase activity, the conversion of fuel to ATP is efficient. However, uncoupling proteins (UCPs) can cause proton leaks resulting in poor fuel conversion efficiency, and some UCPs might control mitochondrial reactive oxygen species (ROS) production. Once viewed as toxic metabolic waste, ROS are now implicated in cell signaling and regulation. Here, we discuss the role of mitochondrial proticity in the context of ROS production and signaling. Copyright © 2012 Elsevier Ltd. All rights reserved.

Fluorescent recovery after photobleaching (FRAP) analysis of nuclear export rates identifies intrinsic features of nucleocytoplasmic transport.

PubMed

Cardarelli, Francesco; Tosti, Luca; Serresi, Michela; Beltram, Fabio; Bizzarri, Ranieri

2012-02-17

A quantitative description of carrier-mediated nuclear export in live cells is presented. To this end, we fused a prototypical leucine-rich nuclear export signal (NES) to GFP as a cargo model and expressed the fluorescent chimera in live CHO-K1 cells. By modeling FRAP data, we calculate the NES affinity for the export machinery and the maximum rate of nuclear export achievable at saturation of endogenous carriers. The measured active-export time through the Nuclear Pore Complex (NPC) is 18 ms, remarkably similar to the previously determined active-import rate. Also, our results reveal that active export/import and active export/passive diffusion fluxes are uncoupled, thus complementing previous reports on active import/passive diffusion uncoupling. These findings suggest differential gating at the NPC level.

Functional reconstitution of Arabidopsis thaliana plant uncoupling mitochondrial protein (AtPUMP1) expressed in Escherichia coli.

PubMed

Borecký, J; Maia, I G; Costa, A D; Jezek, P; Chaimovich, H; de Andrade, P B; Vercesi, A E; Arruda, P

2001-09-14

The Arabidopsis thaliana uncoupling protein (UCP) gene was expressed in Escherichia coli and isolated protein reconstituted into liposomes. Linoleic acid-induced H+ fluxes were sensitive to purine nucleotide inhibition with an apparent K(i) (in mM) of 0.8 (GDP), 0.85 (ATP), 0.98 (GTP), and 1.41 (ADP); the inhibition was pH-dependent. Kinetics of AtPUMP1-mediated H+ fluxes were determined for lauric, myristic, palmitic, oleic, linoleic, and linolenic acids. Properties of recombinant AtPUMP1 indicate that it represents a plant counterpart of animal UCP2 or UCP3. This work brings the functional and genetic approaches together for the first time, providing strong support that AtPUMP1 is truly an UCP.

Anti-obesity efficacy of nanoemulsion oleoresin capsicum in obese rats fed a high-fat diet

PubMed Central

Kim, Joo-Yeon; Lee, Mak-Soon; Jung, Sunyoon; Joo, Hyunjin; Kim, Chong-Tai; Kim, In-Hwan; Seo, Sangjin; Oh, Soojung; Kim, Yangha

2014-01-01

Purpose This study determined the effects of oleoresin capsicum (OC) and nanoemulsion OC (NOC) on obesity in obese rats fed a high-fat diet. Methods The rats were randomly separated into three groups: a high-fat (HF) diet group, HF + OC diet group, and HF + NOC diet group. All groups were fed the diet and water ad libitum for 14 weeks. Results NOC reduced the body weight and adipose tissue mass, whereas OC did not. OC and NOC reduced mRNA levels of adipogenic genes, including peroxisome proliferator-activated receptor (PPAR)-γ, sterol regulatory element-binding protein-1c, and fatty acid-binding protein in white adipose tissue. The mRNA levels of genes related to β-oxidation or thermogenesis including PPAR-α, palmitoyltransferase-1α, and uncoupling protein-2 were increased by the OC and NOC relative to the HF group. Both OC and NOC clearly stimulated AMP-activated protein kinase (AMPK) activity. In particular, PPAR-α, palmitoyltransferase-1α, uncoupling protein-2 expression, and AMPK activity were significantly increased in the NOC group compared to in the OC group. NOC decreased glycerol-3-phosphate dehydrogenase activity whereas OC did not. Conclusion From these results, NOC could be suggested as a potential anti-obesity agent in obese rats fed a HF diet. The effects of the NOC on obesity were associated with changes of multiple gene expression, activation of AMPK, and inhibition of glycerol-3-phosphate dehydrogenase in white adipose tissue. PMID:24403834

Impact of the North Atlantic Oscillation on the trans-Atlantic migrations of the European eel (Anguilla anguilla)

NASA Astrophysics Data System (ADS)

Kettle, A. James; Bakker, Dorothee C. E.; Haines, Keith

2008-09-01

Glass eel catches and FAO (Food and Agricultural Organization) landings of the European freshwater eel (Anguilla anguilla) show a decrease over the past 20 years. The long-term trends in the time series mask an interannual fluctuation, which becomes apparent on the application of a high-pass filter and autocorrelation analysis. Both the FAO landings and the glass eel catches show interannual fluctuations with a repeat period of 6-8 years, similar to the period of the North Atlantic Oscillation (NAO). Most glass eel catch monitoring stations are in phase. The glass eel catches show a significant negative correlation with the NAO lagged by 0-2 years, consistent with the hypothesis that the positive NAO phase has an adverse impact on the larval survival in and migration from the Sargasso Sea spawning location, one year prior to the arrival of the glass eels in Europe and North Africa. The FAO landings can be divided into two groups of different phase that have an approximate correspondence to the NAO dipole in winter rainfall in Europe and North Africa. One group (P) comprises Denmark, Ireland, Morocco, Netherlands, Norway, Sweden, Tunisia, and the United Kingdom, and the other group (N) comprises France, Germany, Italy, Poland, Portugal, Spain, and Turkey. At least for the interannual fluctuations, the success of the glass eel fishery (and eel recruitment) may be coupled with the number of migrating silver eels from the N group of countries and uncoupled with the P group of countries.

Ionospheric refraction effects on TOPEX orbit determination accuracy using the Tracking and Data Relay Satellite System (TDRSS)

NASA Technical Reports Server (NTRS)

Radomski, M. S.; Doll, C. E.

1991-01-01

This investigation concerns the effects on Ocean Topography Experiment (TOPEX) spacecraft operational orbit determination of ionospheric refraction error affecting tracking measurements from the Tracking and Data Relay Satellite System (TDRSS). Although tracking error from this source is mitigated by the high frequencies (K-band) used for the space-to-ground links and by the high altitudes for the space-to-space links, these effects are of concern for the relatively high-altitude (1334 kilometers) TOPEX mission. This concern is due to the accuracy required for operational orbit-determination by the Goddard Space Flight Center (GSFC) and to the expectation that solar activity will still be relatively high at TOPEX launch in mid-1992. The ionospheric refraction error on S-band space-to-space links was calculated by a prototype observation-correction algorithm using the Bent model of ionosphere electron densities implemented in the context of the Goddard Trajectory Determination System (GTDS). Orbit determination error was evaluated by comparing parallel TOPEX orbit solutions, applying and omitting the correction, using the same simulated TDRSS tracking observations. The tracking scenarios simulated those planned for the observation phase of the TOPEX mission, with a preponderance of one-way return-link Doppler measurements. The results of the analysis showed most TOPEX operational accuracy requirements to be little affected by space-to-space ionospheric error. The determination of along-track velocity changes after ground-track adjustment maneuvers, however, is significantly affected when compared with the stringent 0.1-millimeter-per-second accuracy requirements, assuming uncoupled premaneuver and postmaneuver orbit determination. Space-to-space ionospheric refraction on the 24-hour postmaneuver arc alone causes 0.2 millimeter-per-second errors in along-track delta-v determination using uncoupled solutions. Coupling the premaneuver and postmaneuver solutions, however, appears likely to reduce this figure substantially. Plans and recommendations for response to these findings are presented.

77 FR 57534 - Airworthiness Directives; Piper Aircraft, Inc. Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-18

... turbocharger (uncoupled) for cracks, distortion, and evidence indicative of improper surface mating. (3) Inspect the three exhaust system slip joints between each turbocharger and its closest riser for seizure...

49 CFR 218.22 - Utility employee.

Code of Federal Regulations, 2014 CFR

2014-10-01

... uncouple air hoses and other electrical or mechanical connections; prepare rail cars for coupling; set... one or more locomotives coupled, with or without cars) and before commencing any duties with the crew...

49 CFR 218.22 - Utility employee.

Code of Federal Regulations, 2013 CFR

2013-10-01

... uncouple air hoses and other electrical or mechanical connections; prepare rail cars for coupling; set... one or more locomotives coupled, with or without cars) and before commencing any duties with the crew...

49 CFR 218.22 - Utility employee.

Code of Federal Regulations, 2010 CFR

2010-10-01

... uncouple air hoses and other electrical or mechanical connections; prepare rail cars for coupling; set... one or more locomotives coupled, with or without cars) and before commencing any duties with the crew...

Mechanics of adsorption-deformation coupling in porous media

NASA Astrophysics Data System (ADS)

Zhang, Yida

2018-05-01

This work extends Coussy's macroscale theory for porous materials interacting with adsorptive fluid mixtures. The solid-fluid interface is treated as an independent phase that obeys its own mass, momentum and energy balance laws. As a result, a surface strain energy term appears in the free energy balance equation of the solid phase, which further introduces the so-called adsorption stress in the constitutive equations of the porous skeleton. This establishes a fundamental link between the adsorption characteristics of the solid-fluid interface and the mechanical response of the porous media. The thermodynamic framework is quite general in that it recovers the coupled conduction laws, Gibbs isotherm and the Shuttleworth's equation for surface stress, and imposes no constraints on the magnitude of deformation and the functional form of the adsorption isotherms. A rich variety of coupling between adsorption and deformation is recovered as a result of combining different poroelastic models (isotropic vs. anisotropic, linear vs. nonlinear) and adsorption models (unary vs. mixture adsorption, uncoupled vs. stretch-dependent adsorption). These predictions are discussed against the backdrop of recent experimental data on coal swelling subjected to CO2 and CO2sbnd CH4 injections, showing the capability and versatility of the theory in capturing adsorption-induced deformation of porous materials.

Ca2+ signaling in injured in situ endothelium of rat aorta.

PubMed

Berra-Romani, Roberto; Raqeeb, Abdul; Avelino-Cruz, José Everardo; Moccia, Francesco; Oldani, Amanda; Speroni, Francisco; Taglietti, Vanni; Tanzi, Franco

2008-09-01

The inner wall of excised rat aorta was scraped by a microelectrode and Ca2+ signals were investigated by fluorescence microscopy in endothelial cells (ECs) directly coupled with injured cells. The injury caused an immediate increase in the intracellular Ca2+ concentration ([Ca2+]i), followed by a long-lasting decay phase due to Ca2+ influx from extracellular space. The immediate response was mainly due to activation of purinergic receptors, as shown by the effect of P2X and P2Y receptors agonists and antagonists, such as suramin, alpha,beta-MeATP, MRS-2179 and 2-MeSAMP. Inhibition of store-operated Ca2+ influx did not affect either the peak response or the decay phase. Furthermore, the latter was: (i) insensitive to phospholipase C inhibition, (ii) sensitive to the gap junction blockers, palmitoleic acid, heptanol, octanol and oleamide, and (iii) sensitive to La3+ and Ni2+, but not to Gd3+. Finally, ethidium bromide or Lucifer Yellow did not enter ECs facing the scraped area. These results suggest that endothelium scraping: (i) causes a short-lasting stimulation of healthy ECs by extracellular nucleotides released from damaged cells and (ii) uncouples the hemichannels of the ECs facing the injury site; these hemichannels do not fully close and allow a long-lasting Ca2+ entry.

Redefining metamorphosis in spiny lobsters: molecular analysis of the phyllosoma to puerulus transition in Sagmariasus verreauxi

PubMed Central

Ventura, Tomer; Fitzgibbon, Quinn P.; Battaglene, Stephen C.; Elizur, Abigail

2015-01-01

The molecular understanding of crustacean metamorphosis is hindered by small sized individuals and inability to accurately define molt stages. We used the spiny lobster Sagmariasus verreauxi where the large, transparent larvae enable accurate tracing of the transition from a leaf-shaped phyllosoma to an intermediate larval-juvenile phase (puerulus). Transcriptomic analysis of larvae at well-defined stages prior to, during, and following this transition show that the phyllosoma-puerulus metamorphic transition is accompanied by vast transcriptomic changes exceeding 25% of the transcriptome. Notably, genes previously identified as regulating metamorphosis in other crustaceans do not fluctuate during this transition but in the later, morphologically-subtle puerulus-juvenile transition, indicating that the dramatic phyllosoma-puerulus morphological shift relies on a different, yet to be identified metamorphic mechanism. We examined the change in expression of domains and gene families, with focus on several key genes. Our research implies that the separation in molecular triggering systems between the phyllosoma-puerulus and puerulus-juvenile transitions might have enabled the extension of the oceanic phase in spiny lobsters. Study of similar transitions, where metamorphosis is uncoupled from the transition into the benthic juvenile form, in other commercially important crustacean groups might show common features to point on the evolutionary advantage of this two staged regulation. PMID:26311524

Redefining metamorphosis in spiny lobsters: molecular analysis of the phyllosoma to puerulus transition in Sagmariasus verreauxi.

PubMed

Ventura, Tomer; Fitzgibbon, Quinn P; Battaglene, Stephen C; Elizur, Abigail

2015-08-27

The molecular understanding of crustacean metamorphosis is hindered by small sized individuals and inability to accurately define molt stages. We used the spiny lobster Sagmariasus verreauxi where the large, transparent larvae enable accurate tracing of the transition from a leaf-shaped phyllosoma to an intermediate larval-juvenile phase (puerulus). Transcriptomic analysis of larvae at well-defined stages prior to, during, and following this transition show that the phyllosoma-puerulus metamorphic transition is accompanied by vast transcriptomic changes exceeding 25% of the transcriptome. Notably, genes previously identified as regulating metamorphosis in other crustaceans do not fluctuate during this transition but in the later, morphologically-subtle puerulus-juvenile transition, indicating that the dramatic phyllosoma-puerulus morphological shift relies on a different, yet to be identified metamorphic mechanism. We examined the change in expression of domains and gene families, with focus on several key genes. Our research implies that the separation in molecular triggering systems between the phyllosoma-puerulus and puerulus-juvenile transitions might have enabled the extension of the oceanic phase in spiny lobsters. Study of similar transitions, where metamorphosis is uncoupled from the transition into the benthic juvenile form, in other commercially important crustacean groups might show common features to point on the evolutionary advantage of this two staged regulation.

Coordination changes and auto-hydroxylation of FIH-1: uncoupled O2-activation in a human hypoxia sensor

PubMed Central

Chen, Yuan-Han; Comeaux, Lindsay M.; Herbst, Robert W.; Saban, Evren; Kennedy, David C.; Maroney, Michael J.; Knapp, Michael J.

2008-01-01

Hypoxia sensing is the generic term for pO2-sensing in humans and other higher organisms. These cellular responses to pO2 are largely controlled by enzymes that belong to the Fe(II) α-ketoglutarate (αKG) dependent dioxygenase superfamily, including the human enzyme called the Factor Inhibiting HIF (FIH-1), which couples O2-activation to the hydroxylation of the Hypoxia Inducible Factor α (HIFα). Uncoupled O2-activation by human FIH-1 was studied by exposing the resting form of FIH-1, (αKG+Fe)FIH-1, to air in the absence of HIFα. Uncoupling lead to two distinct enzyme oxidations, one a purple chromophore (λmax = 583 nm) arising from enzyme auto-hydroxylation of Trp296, forming an Fe(III)–O–Trp296 chromophore (Y.-H. Chen, L. M. Comeaux, S. J. Eyles, M. J. Knapp, Chem. Commun. (2008) DOI:10.1039/B809099H); the other a yellow chromophore due to Fe(III) in the active site, which under some conditions also contained variable levels of an oxygenated surface residue, (oxo)Met275. The kinetics of purple FIH-1 formation were independent of Fe(II) and αKG concentrations, however product yield was saturable with increasing [αKG] and required excess Fe(II). Yellow FIH-1 was formed from (succinate+Fe)FIH-1, or by glycerol addition to (αKG+Fe)FIH-1, suggesting that glycerol could intercept the active oxidant from the FIH-1 active site and prevent hydroxylation. Both purple and yellow FIH-1 contained high-spin, rhombic Fe(III) centers, as shown by low temperature EPR. XAS indicated distorted octahedral Fe(III) geometries, with subtle differences in inner-shell ligands for yellow and purple FIH-1. EPR of Co(II)-substituted FIH-1, (αKG+Co)FIH-1, indicated a mixture of 5-coordinate and 6-coordinate enzyme forms, suggesting that resting FIH-1 can readily undergo uncoupled O2-activation by loss of an H2O ligand from the metal center. PMID:18805587

Multiple, simultaneous, independent gradients for a versatile multidimensional liquid chromatography. Part II: Application 2: Computer controlled pH gradients in the presence of urea provide improved separation of proteins: Stability influenced anion and cation exchange chromatography.

PubMed

Hirsh, Allen G; Tsonev, Latchezar I

2017-04-28

This paper details the use of a method of creating controlled pH gradients (pISep) to improve the separation of protein isoforms on ion exchange (IEX) stationary phases in the presence of various isocratic levels of urea. The pISep technology enables the development of computer controlled pH gradients on both cationic (CEX) and anionic (AEX) IEX stationary phases over the very wide pH range from 2 to 12. In pISep, titration curves generated by proportional mixing of the acidic and basic pISep working buffers alone, or in the presence of non-buffering solutes such as the neutral salt NaCl (0-1M), polar organics such as urea (0-8M) or acetonitrile (0-80 Vol%), can be fitted with high fidelity using high order polynomials which, in turn allows construction of a mathematical manifold %A (% acidic pISep buffer) vs. pH vs. [non-buffering solute], permitting precise computer control of pH and the non-buffering solute concentration allowing formation of dual uncoupled liquid chromatographic (LC) gradients of arbitrary shape (Hirsh and Tsonev, 2012 [1]). The separation of protein isoforms examined in this paper by use of such pH gradients in the presence of urea demonstrates the fractionation power of a true single step two dimensional liquid chromatography which we denote as Stability-Influenced Ion Exchange Chromatography (SIIEX). We present evidence that SIIEX is capable of increasing the resolution of protein isoforms difficult to separate by ordinary pH gradient IEX, and potentially simplifying the development of laboratory and production purification strategies involving on-column simultaneous pH and urea unfolding or refolding of targeted proteins. We model some of the physics implied by the dynamics of the observed protein fractionations as a function of both urea concentration and pH assuming that urea-induced native state unfolding competes with native state electrostatic interaction binding to an IEX stationary phase. Implications for in vivo protein-membrane interactions are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Self-Consistent Chaotic Transport in a High-Dimensional Mean-Field Hamiltonian Map Model

DOE PAGES

Martínez-del-Río, D.; del-Castillo-Negrete, D.; Olvera, A.; ...

2015-10-30

We studied the self-consistent chaotic transport in a Hamiltonian mean-field model. This model provides a simplified description of transport in marginally stable systems including vorticity mixing in strong shear flows and electron dynamics in plasmas. Self-consistency is incorporated through a mean-field that couples all the degrees-of-freedom. The model is formulated as a large set of N coupled standard-like area-preserving twist maps in which the amplitude and phase of the perturbation, rather than being constant like in the standard map, are dynamical variables. Of particular interest is the study of the impact of periodic orbits on the chaotic transport and coherentmore » structures. Furthermore, numerical simulations show that self-consistency leads to the formation of a coherent macro-particle trapped around the elliptic fixed point of the system that appears together with an asymptotic periodic behavior of the mean field. To model this asymptotic state, we introduced a non-autonomous map that allows a detailed study of the onset of global transport. A turnstile-type transport mechanism that allows transport across instantaneous KAM invariant circles in non-autonomous systems is discussed. As a first step to understand transport, we study a special type of orbits referred to as sequential periodic orbits. Using symmetry properties we show that, through replication, high-dimensional sequential periodic orbits can be generated starting from low-dimensional periodic orbits. We show that sequential periodic orbits in the self-consistent map can be continued from trivial (uncoupled) periodic orbits of standard-like maps using numerical and asymptotic methods. Normal forms are used to describe these orbits and to find the values of the map parameters that guarantee their existence. Numerical simulations are used to verify the prediction from the asymptotic methods.« less

Self-Consistent Chaotic Transport in a High-Dimensional Mean-Field Hamiltonian Map Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martínez-del-Río, D.; del-Castillo-Negrete, D.; Olvera, A.

We studied the self-consistent chaotic transport in a Hamiltonian mean-field model. This model provides a simplified description of transport in marginally stable systems including vorticity mixing in strong shear flows and electron dynamics in plasmas. Self-consistency is incorporated through a mean-field that couples all the degrees-of-freedom. The model is formulated as a large set of N coupled standard-like area-preserving twist maps in which the amplitude and phase of the perturbation, rather than being constant like in the standard map, are dynamical variables. Of particular interest is the study of the impact of periodic orbits on the chaotic transport and coherentmore » structures. Furthermore, numerical simulations show that self-consistency leads to the formation of a coherent macro-particle trapped around the elliptic fixed point of the system that appears together with an asymptotic periodic behavior of the mean field. To model this asymptotic state, we introduced a non-autonomous map that allows a detailed study of the onset of global transport. A turnstile-type transport mechanism that allows transport across instantaneous KAM invariant circles in non-autonomous systems is discussed. As a first step to understand transport, we study a special type of orbits referred to as sequential periodic orbits. Using symmetry properties we show that, through replication, high-dimensional sequential periodic orbits can be generated starting from low-dimensional periodic orbits. We show that sequential periodic orbits in the self-consistent map can be continued from trivial (uncoupled) periodic orbits of standard-like maps using numerical and asymptotic methods. Normal forms are used to describe these orbits and to find the values of the map parameters that guarantee their existence. Numerical simulations are used to verify the prediction from the asymptotic methods.« less

A three dimensional finite element formulation for thermoviscoelastic orthotropic media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zocher, M.A.

1997-12-31

A numerical algorithm for the efficient solution of the uncoupled quasistatic initial/boundary value problem involving orthotropic linear viscoelastic media undergoing thermal and/or mechanical deformation is briefly outlined.

A Coupled/Uncoupled Computational Scheme for Deformation and Fatigue Damage Analysis of Unidirectional Metal-Matrix Composites

NASA Technical Reports Server (NTRS)

Wilt, Thomas E.; Arnold, Steven M.; Saleeb, Atef F.

1997-01-01

A fatigue damage computational algorithm utilizing a multiaxial, isothermal, continuum-based fatigue damage model for unidirectional metal-matrix composites has been implemented into the commercial finite element code MARC using MARC user subroutines. Damage is introduced into the finite element solution through the concept of effective stress that fully couples the fatigue damage calculations with the finite element deformation solution. Two applications using the fatigue damage algorithm are presented. First, an axisymmetric stress analysis of a circumferentially reinforced ring, wherein both the matrix cladding and the composite core were assumed to behave elastic-perfectly plastic. Second, a micromechanics analysis of a fiber/matrix unit cell using both the finite element method and the generalized method of cells (GMC). Results are presented in the form of S-N curves and damage distribution plots.

Stabilization of cartwheel-less centrioles for duplication requires CEP295-mediated centriole to centrosome conversion

PubMed Central

Izquierdo, Denisse; Wang, Won-Jing; Uryu, Kunihiro; Tsou, Meng-Fu Bryan

2014-01-01

SUMMARY Vertebrate centrioles lose their geometric scaffold, the cartwheel, during mitosis, concurrently with gaining the ability to recruit the pericentriolar material (PCM) and thereby function as the centrosome. Cartwheel removal has recently been implicated in centriole duplication, but whether “cartwheel-less” centrioles are intrinsically stable, or must be maintained through other modifications remains unclear. Here, we identify a newborn centriole-enriched protein, KIAA1731/CEP295, specifically mediating centriole-to-centrosome conversion but dispensable for cartwheel removal. In the absence of CEP295, centrioles form in S/G2 phase, and lose their associated cartwheel in mitosis, but cannot be converted to centrosomes, uncoupling the two events. Strikingly, centrioles devoid of both the PCM and cartwheel progressively lose centriolar components, whereas centrioles associating with either the cartwheel or PCM alone can exist stably. Thus, cartwheel removal can have grave repercussions to centriole stability, and centriole-to-centrosome conversion mediated by CEP295 must occur in parallel to maintain cartwheel-less centrioles for duplication. PMID:25131205

Early manifestation of arm-leg coordination during stepping on a surface in human neonates.

PubMed

La Scaleia, Valentina; Ivanenko, Y; Fabiano, A; Sylos-Labini, F; Cappellini, G; Picone, S; Paolillo, P; Di Paolo, A; Lacquaniti, F

2018-04-01

The accomplishment of mature locomotor movements relies upon the integrated coordination of the lower and upper limbs and the trunk. Human adults normally swing their arms and a quadrupedal limb coordination persists during bipedal walking despite a strong corticospinal control of the upper extremities that allows to uncouple this connection during voluntary activities. Here we investigated arm-leg coordination during stepping responses on a surface in human neonates. In eight neonates, we found the overt presence of alternating arm-leg oscillations, the arms moving up and down in alternation with ipsilateral lower limb movements. These neonates moved the diagonal limbs together, and the peak of the arm-to-trunk angle (i.e., maximum vertical excursion of the arm) occurred around the end of the ipsilateral stance phase, as it occurs during typical adult walking. Although episodes of arm-leg coordination were sporadic in our sample of neonates, their presence provides significant evidence for a neural coupling between the upper and lower limbs during early ontogenesis of locomotion in humans.

Hematopoietic stem cells can differentiate into restricted myeloid progenitors before cell division in mice.

PubMed

Grinenko, Tatyana; Eugster, Anne; Thielecke, Lars; Ramasz, Beáta; Krüger, Anja; Dietz, Sevina; Glauche, Ingmar; Gerbaulet, Alexander; von Bonin, Malte; Basak, Onur; Clevers, Hans; Chavakis, Triantafyllos; Wielockx, Ben

2018-05-15

Hematopoietic stem cells (HSCs) continuously replenish all blood cell types through a series of differentiation steps and repeated cell divisions that involve the generation of lineage-committed progenitors. However, whether cell division in HSCs precedes differentiation is unclear. To this end, we used an HSC cell-tracing approach and Ki67 RFP knock-in mice, in a non-conditioned transplantation model, to assess divisional history, cell cycle progression, and differentiation of adult HSCs. Our results reveal that HSCs are able to differentiate into restricted progenitors, especially common myeloid, megakaryocyte-erythroid and pre-megakaryocyte progenitors, without undergoing cell division and even before entering the S phase of the cell cycle. Additionally, the phenotype of the undivided but differentiated progenitors correlated with the expression of lineage-specific genes and loss of multipotency. Thus HSC fate decisions can be uncoupled from physical cell division. These results facilitate a better understanding of the mechanisms that control fate decisions in hematopoietic cells.

Dynamics of entanglement and the Schmidt gap in a driven light-matter system

NASA Astrophysics Data System (ADS)

Gómez-Ruiz, F. J.; Mendoza-Arenas, J. J.; Acevedo, O. L.; Rodríguez, F. J.; Quiroga, L.; Johnson, N. F.

2018-01-01

The ability to modify light-matter coupling in time (e.g. using external pulses) opens up the exciting possibility of generating and probing new aspects of quantum correlations in many-body light-matter systems. Here we study the impact of such a pulsed coupling on the light-matter entanglement in the Dicke model as well as the respective subsystem quantum dynamics. Our dynamical many-body analysis exploits the natural partition between the radiation and matter degrees of freedom, allowing us to explore time-dependent intra-subsystem quantum correlations by means of squeezing parameters, and the inter-subsystem Schmidt gap for different pulse duration (i.e. ramping velocity) regimes—from the near adiabatic to the sudden quench limits. Our results reveal that both types of quantities indicate the emergence of the superradiant phase when crossing the quantum critical point. In addition, at the end of the pulse light and matter remain entangled even though they become uncoupled, which could be exploited to generate entangled states in non-interacting systems.

Oxyntomodulin regulates resetting of the liver circadian clock by food

PubMed Central

Landgraf, Dominic; Tsang, Anthony H; Leliavski, Alexei; Koch, Christiane E; Barclay, Johanna L; Drucker, Daniel J; Oster, Henrik

2015-01-01

Circadian clocks coordinate 24-hr rhythms of behavior and physiology. In mammals, a master clock residing in the suprachiasmatic nucleus (SCN) is reset by the light–dark cycle, while timed food intake is a potent synchronizer of peripheral clocks such as the liver. Alterations in food intake rhythms can uncouple peripheral clocks from the SCN, resulting in internal desynchrony, which promotes obesity and metabolic disorders. Pancreas-derived hormones such as insulin and glucagon have been implicated in signaling mealtime to peripheral clocks. In this study, we identify a novel, more direct pathway of food-driven liver clock resetting involving oxyntomodulin (OXM). In mice, food intake stimulates OXM secretion from the gut, which resets liver transcription rhythms via induction of the core clock genes Per1 and 2. Inhibition of OXM signaling blocks food-mediated resetting of hepatocyte clocks. These data reveal a direct link between gastric filling with food and circadian rhythm phasing in metabolic tissues. DOI: http://dx.doi.org/10.7554/eLife.06253.001 PMID:25821984

OXPHOS-Dependent Cells Identify Environmental Disruptors of Mitochondrial Function

EPA Science Inventory

Mitochondrial dysfunction is associated with numerous chronic diseases including metabolic syndrome. Environmental chemicals can impair mitochondrial function through numerous mechanisms such as membrane disruption, complex inhibition and electron transport chain uncoupling. Curr...

Uncoupling proteins (UCP) in unicellular eukaryotes: true UCPs or UCP1-like acting proteins?

PubMed

Luévano-Martínez, Luis Alberto

2012-04-05

Uncoupling proteins belong to the superfamily of mitochondrial anion carriers. They are apparently present throughout the Eukarya domain in which only some members have an established physiological function, i.e. UCP1 from brown adipose tissue is involved in non-shivering thermogenesis. However, the proteins responsible for the phenotype observed in unicellular organisms have not been characterized. In this report we analyzed functional evidence concerning unicellular UCPs and found that true UCPs are restricted to some taxonomical groups while proteins conferring a UCP1-like phenotype to fungi and most protists are the result of a promiscuous activity exerted by other mitochondrial anion carriers. We describe a possible evolutionary route followed by these proteins by which they acquire this promiscuous mechanism. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Fluorescent Recovery after Photobleaching (FRAP) Analysis of Nuclear Export Rates Identifies Intrinsic Features of Nucleocytoplasmic Transport*

PubMed Central

Cardarelli, Francesco; Tosti, Luca; Serresi, Michela; Beltram, Fabio; Bizzarri, Ranieri

2012-01-01

A quantitative description of carrier-mediated nuclear export in live cells is presented. To this end, we fused a prototypical leucine-rich nuclear export signal (NES) to GFP as a cargo model and expressed the fluorescent chimera in live CHO-K1 cells. By modeling FRAP data, we calculate the NES affinity for the export machinery and the maximum rate of nuclear export achievable at saturation of endogenous carriers. The measured active-export time through the Nuclear Pore Complex (NPC) is 18 ms, remarkably similar to the previously determined active-import rate. Also, our results reveal that active export/import and active export/passive diffusion fluxes are uncoupled, thus complementing previous reports on active import/passive diffusion uncoupling. These findings suggest differential gating at the NPC level. PMID:22190681

Uncoupling binding of substrate CO from turnover by vanadium nitrogenase.

PubMed

Lee, Chi Chung; Fay, Aaron W; Weng, Tsu-Chien; Krest, Courtney M; Hedman, Britt; Hodgson, Keith O; Hu, Yilin; Ribbe, Markus W

2015-11-10

Biocatalysis by nitrogenase, particularly the reduction of N2 and CO by this enzyme, has tremendous significance in environment- and energy-related areas. Elucidation of the detailed mechanism of nitrogenase has been hampered by the inability to trap substrates or intermediates in a well-defined state. Here, we report the capture of substrate CO on the resting-state vanadium-nitrogenase in a catalytically competent conformation. The close resemblance of this active CO-bound conformation to the recently described structure of CO-inhibited molybdenum-nitrogenase points to the mechanistic relevance of sulfur displacement to the activation of iron sites in the cofactor for CO binding. Moreover, the ability of vanadium-nitrogenase to bind substrate in the resting-state uncouples substrate binding from subsequent turnover, providing a platform for generation of defined intermediate(s) of both CO and N2 reduction.

Pericyte degeneration leads to neurovascular uncoupling and limits oxygen supply to brain

PubMed Central

Kisler, Kassandra; Nelson, Amy R.; Rege, Sanket V.; Ramanathan, Anita; Wang, Yaoming; Ahuja, Ashim; Lazic, Divna; Tsai, Philbert S.; Zhao, Zhen; Zhou, Yi; Boas, David A.; Sakadžić, Sava; Zlokovic, Berislav V.

2017-01-01

Pericytes are perivascular mural cells of brain capillaries that are positioned centrally within the neurovascular unit between endothelial cells, astrocytes and neurons. This unique position allows them to play a major role in regulating key neurovascular functions of the brain. The role of pericytes in the regulation of cerebral blood flow (CBF) and neurovascular coupling remains, however, debatable. Using loss-of-function pericyte-deficient mice, here we show that pericyte degeneration diminishes global and individual capillary CBF responses to neuronal stimulus resulting in neurovascular uncoupling, reduced oxygen supply to brain and metabolic stress. We show that these neurovascular deficits lead over time to impaired neuronal excitability and neurodegenerative changes. Thus, pericyte degeneration as seen in neurological disorders such as Alzheimer’s disease may contribute to neurovascular dysfunction and neurodegeneration associated with human disease. PMID:28135240

Cell death and cell lysis are separable events during pyroptosis

PubMed Central

DiPeso, Lucian; Ji, Daisy X; Vance, Russell E; Price, Jordan V

2017-01-01

Although much insight has been gained into the mechanisms by which activation of the inflammasome can trigger pyroptosis in mammalian cells, the precise kinetics of the end stages of pyroptosis have not been well characterized. Using time-lapse fluorescent imaging to analyze the kinetics of pyroptosis in individual murine macrophages, we observed distinct stages of cell death and cell lysis. Our data demonstrate that cell membrane permeability resulting from gasdermin D pore formation is coincident with the cessation of cell movement, loss of mitochondrial activity, and cell swelling, events that can be uncoupled from cell lysis. We propose a model of pyroptosis in which cell death can occur independently of cell lysis. The uncoupling of cell death from cell lysis may allow for better control of cytosolic contents upon activation of the inflammasome. PMID:29147575

Highly eccentric hip-hop solutions of the 2 N-body problem

NASA Astrophysics Data System (ADS)

Barrabés, Esther; Cors, Josep M.; Pinyol, Conxita; Soler, Jaume

2010-02-01

We show the existence of families of hip-hop solutions in the equal-mass 2 N-body problem which are close to highly eccentric planar elliptic homographic motions of 2 N bodies plus small perpendicular non-harmonic oscillations. By introducing a parameter ɛ, the homographic motion and the small amplitude oscillations can be uncoupled into a purely Keplerian homographic motion of fixed period and a vertical oscillation described by a Hill type equation. Small changes in the eccentricity induce large variations in the period of the perpendicular oscillation and give rise, via a Bolzano argument, to resonant periodic solutions of the uncoupled system in a rotating frame. For small ɛ≠0, the topological transversality persists and Brouwer’s fixed point theorem shows the existence of this kind of solutions in the full system.

Absorption enhancement in type-II coupled quantum rings due to existence of quasi-bound states

NASA Astrophysics Data System (ADS)

Hsieh, Chi-Ti; Lin, Shih-Yen; Chang, Shu-Wei

2018-02-01

The absorption of type-II nanostructures is often weaker than type-I counterpart due to spatially separated electrons and holes. We model the bound-to-continuum absorption of type-II quantum rings (QRs) using a multiband source-radiation approach using the retarded Green function in the cylindrical coordinate system. The selection rules due to the circular symmetry for allowed transitions of absorption are utilized. The bound-tocontinuum absorptions of type-II GaSb coupled and uncoupled QRs embedded in GaAs matrix are compared here. The GaSb QRs act as energy barriers for electrons but potential wells for holes. For the coupled QR structure, the region sandwiched between two QRs forms a potential reservoir of quasi-bound electrons. Electrons in these states, though look like bound ones, would ultimately tunnel out of the reservoir through barriers. Multiband perfectly-matched layers are introduced to model the tunneling of quasi-bound states into open space. Resonance peaks are observed on the absorption spectra of type-II coupled QRs due to the formation of quasi-bound states in conduction bands, but no resonance exist in the uncoupled QR. The tunneling time of these metastable states can be extracted from the resonance and is in the order of ten femtoseconds. Absorption of coupled QRs is significantly enhanced as compared to that of uncoupled ones in certain spectral windows of interest. These features may improve the performance of photon detectors and photovoltaic devices based on type-II semiconductor nanostructures.

Uncoupling protein and ATP/ADP carrier increase mitochondrial proton conductance after cold adaptation of king penguins

PubMed Central

Talbot, Darren A; Duchamp, Claude; Rey, Benjamin; Hanuise, Nicolas; Rouanet, Jean Louis; Sibille, Brigitte; Brand, Martin D

2004-01-01

Juvenile king penguins develop adaptive thermogenesis after repeated immersion in cold water. However, the mechanisms of such metabolic adaptation in birds are unknown, as they lack brown adipose tissue and uncoupling protein-1 (UCP1), which mediate adaptive non-shivering thermogenesis in mammals. We used three different groups of juvenile king penguins to investigate the mitochondrial basis of avian adaptive thermogenesis in vitro. Skeletal muscle mitochondria isolated from penguins that had never been immersed in cold water showed no superoxide-stimulated proton conductance, indicating no functional avian UCP. Skeletal muscle mitochondria from penguins that had been either experimentally immersed or naturally adapted to cold water did possess functional avian UCP, demonstrated by a superoxide-stimulated, GDP-inhibitable proton conductance across their inner membrane. This was associated with a markedly greater abundance of avian UCP mRNA. In the presence (but not the absence) of fatty acids, these mitochondria also showed a greater adenine nucleotide translocase-catalysed proton conductance than those from never-immersed penguins. This was due to an increase in the amount of adenine nucleotide translocase. Therefore, adaptive thermogenesis in juvenile king penguins is linked to two separate mechanisms of uncoupling of oxidative phosphorylation in skeletal muscle mitochondria: increased proton transport activity of avian UCP (dependent on superoxide and inhibited by GDP) and increased proton transport activity of the adenine nucleotide translocase (dependent on fatty acids and inhibited by carboxyatractylate). PMID:15146050

Tuning the hydrophobicity overcomes unfavorable deprotonation making octylamino-substituted 7-nitrobenz-2-oxa-1,3-diazole (n-octylamino-NBD) a protonophore and uncoupler of oxidative phosphorylation in mitochondria.

PubMed

Denisov, Stepan S; Kotova, Elena A; Khailova, Ljudmila S; Korshunova, Galina A; Antonenko, Yuri N

2014-08-01

The environmentally sensitive fluorescent probe 7-nitrobenz-2-oxa-1,3-diazole (NBD) is generally utilized to monitor dynamic properties of membrane lipids and proteins. Here we studied the behavior of a homologous series of 4-n-alkylamino-substituted NBD derivatives (NBD-Cn; n=4, 6, 8, 9, 10, 12) in planar lipid bilayers, liposomes and isolated mitochondria. NBD-C10 induced proton conductivity in planar lipid membranes, while NBD-C4 was ineffective. The NBD-Cn compounds readily provoked proton permeability of neutral liposomes being less effective in negatively charged liposomes. NBD-Cn increased the respiration rate and reduced the membrane potential of isolated rat liver mitochondria. Remarkably, the bell-shaped dependence of the uncoupling activity of NBD-Cn on the alkyl chain length was found in mitochondria in contrast to the monotonous dependence in liposomes. The effect of NBD-Cn on the respiration correlated with that on proton permeability of the inner mitochondrial membrane, as measured by mitochondria swelling. Binding of NBD-Cn to mitochondria increased with n, as shown by fluorescence correlation spectroscopy. It was concluded that despite a pKa value of the amino group in NBD-Cn being about 10, i.e. far from the physiological pH range, the expected hindering of the uncoupling activity could be overcome by inserting the alkyl chain of a certain length. Copyright © 2014 Elsevier B.V. All rights reserved.

Calcium-ion transport by intact Ehrlich ascites-tumour cells. Role of respiratory substrates, Pi and temperature.

PubMed

Charlton, R R; Wenner, C E

1978-03-15

1. The interaction of intact Ehrlich ascites-tumour cells with Ca2+ at 37 degrees C consists of Ca2+ uptake followed by efflux from the cells. Under optimum conditions, two or three cycles of uptake and efflux are observed in the first 15 min after Ca2+ addition. 2. The respiratory substrates malate, succinate and ascorbate plus p-phenylenediamine support Ca2+ uptake. Ca2+ uptake at 37 degrees C is sensitive to the respiratory inhibitors rotenone and antimycin A when appropriate substrates are present. Ca2+ uptake and retention are inhibited by the uncoupler S-13. 3. Increasing extracellular Pi (12 to 30 mM) stimulates uncoupler-sensitive Ca2+ uptake, which reaches a maximum extent of 15 nmol/mg of protein when supported by succinate respiration. Ca2+ efflux is partially inhibited at 30 mM-Pi. 4. Optimum Ca2+ uptake occurs in the presence of succinate and Pi, suggesting that availability of substrate and Pi are rate-limiting. K. Ca2+ uptake occurs at 4 degrees C and is sensitive to uncouplers and oligomycin. Ca2+ efflux at this temperature is minimal. These data are consistent with a model in which passive diffusion of Ca2+ through the plasma membrane is followed by active uptake by the mitochondria. Ca2+ uptake is supported by substrates entering respiration at all three energy-coupling sites. Ca2+ efflux appears to be an active process with a high temperature coefficient.

Effect of Zingiber officinale Supplementation on Obesity Management with Respect to the Uncoupling Protein 1 -3826A>G and ß3-adrenergic Receptor Trp64Arg Polymorphism.

PubMed

Ebrahimzadeh Attari, Vahideh; Asghari Jafarabadi, Mohammad; Zemestani, Maryam; Ostadrahimi, Alireza

2015-07-01

The present study aimed to investigate the effect of ginger (Zingiber officinale) supplementation on some obesity-associated parameters, with nutrigenetics approach. Accordingly, 80 eligible obese women (aged 18-45 years) were randomly assigned to receive either ginger (2-g ginger rhizomes powder as two 1-g tablets per day) or placebo supplements (corn starch with the same amount) for 12 weeks. Subjects were tested for changes in body weight, body mass index, waist and hip circumferences, body composition, appetite score, and dietary intake. Moreover, participants were genotyped for the -3826A>G and Trp64Arg polymorphisms of uncoupling protein 1 and ß3-adrenergic receptor genes, respectively. Over 12 weeks, ginger supplementation resulted in a slight but statistically significant decrease in all anthropometric measurements and total appetite score as compared with placebo group, which were more pronounced in subjects with the AA genotype for uncoupling protein 1 and Trp64Trp genotype for ß3-adrenergic receptor gene. However, there was no significant difference in changes of body composition and total energy and macronutrients intake between groups. In conclusion, our findings suggest that ginger consumption has potential in managing obesity, accompanying with an intervention-genotype interaction effect. However, further clinical trials need to explore ginger's efficacy as an anti-obesity agent in the form of powder, extract, or its active components. Copyright © 2015 John Wiley & Sons, Ltd.

Destabilization of mitochondrial functions as a target against breast cancer progression: Role of TPP{sup +}-linked-polyhydroxybenzoates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sandoval-Acuña, Cristian

Mitochondrion is an accepted molecular target in cancer treatment since it exhibits a higher transmembrane potential in cancer cells, making it susceptible to be targeted by lipophilic-delocalized cations of triphenylphosphonium (TPP{sup +}). Thus, we evaluated five TPP{sup +}-linked decyl polyhydroxybenzoates as potential cytotoxic agents in several human breast cancer cell lines that differ in estrogen receptor and HER2/neu expression, and in metabolic profile. Results showed that all cell lines tested were sensitive to the cytotoxic action of these compounds. The mechanism underlying the cytotoxicity would be triggered by their weak uncoupling effect on the oxidative phosphorylation system, while having amore » wider and safer therapeutic range than other uncouplers and a significant lowering in transmembrane potential. Noteworthy, while the TPP{sup +}-derivatives alone led to almost negligible losses of ATP, when these were added in the presence of an AMP-activated protein kinase inhibitor, the levels of ATP fell greatly. Overall, data presented suggest that decyl polyhydroxybenzoates-TPP{sup +} and its derivatives warrant future investigation as potential anti-tumor agents. - Highlights: • TPP{sup +}-polyhydroxybenzoates are cytotoxic to various subtypes of breast cancer cells. • Cytotoxicity is not-dependent on the expression of estrogen/growth factor receptors. • Cytotoxicity appears to be triggered by a weak mitochondrial uncoupling effect. • Effects include loss of transmembrane potential and apoptosis was detected. • TPP{sup +}-polyhydroxybenzoates inhibit migration of highly metastatic cells.« less

PSD-95 uncoupling from NMDA receptors by Tat- N-dimer ameliorates neuronal depolarization in cortical spreading depression.

PubMed

Kucharz, Krzysztof; Søndergaard Rasmussen, Ida; Bach, Anders; Strømgaard, Kristian; Lauritzen, Martin

2017-05-01

Cortical spreading depression is associated with activation of NMDA receptors, which interact with the postsynaptic density protein 95 (PSD-95) that binds to nitric oxide synthase (nNOS). Here, we tested whether inhibition of the nNOS/PSD-95/NMDA receptor complex formation by anti-ischemic compound, UCCB01-144 (Tat- N-dimer) ameliorates the persistent effects of cortical spreading depression on cortical function. Using in vivo two-photon microscopy in somatosensory cortex in mice, we show that fluorescently labelled Tat- N-dimer readily crosses blood-brain barrier and accumulates in nerve cells during the first hour after i.v. injection. The Tat- N-dimer suppressed stimulation-evoked synaptic activity by 2-20%, while cortical blood flow and cerebral oxygen metabolic (CMRO 2 ) responses were preserved. During cortical spreading depression, the Tat- N-dimer reduced the average amplitude of the negative shift in direct current potential by 33% (4.1 mV). Furthermore, the compound diminished the average depression of spontaneous electrocorticographic activity by 11% during first 40 min of post-cortical spreading depression recovery, but did not mitigate the suppressing effect of cortical spreading depression on cortical blood flow and CMRO 2 . We suggest that uncoupling of PSD-95 from NMDA receptors reduces overall neuronal excitability and the amplitude of the spreading depolarization wave. These findings may be of interest for understanding the neuroprotective effects of the nNOS/PSD-95 uncoupling in stroke.

Molecular identification and functional characterisation of uncoupling protein 4 in larva and pupa fat body mitochondria from the beetle Zophobas atratus.

PubMed

Slocinska, Malgorzata; Antos-Krzeminska, Nina; Rosinski, Grzegorz; Jarmuszkiewicz, Wieslawa

2012-08-01

Uncoupling protein 4 (UCP4) is a member of the UCP subfamily that mediates mitochondrial uncoupling, and sequence alignment predicts the existence of UCP4 in several insects. The present study demonstrates the first molecular identification of a partial Zophobas atratus UCP4-coding sequence and the functional characterisation of ZaUCP4 in the mitochondria of larval and pupal fat bodies of the beetle. ZaUCP4 shows a high similarity to predicted insect UCP4 isoforms and known mammalian UCP4s, both at the nucleotide and amino acid sequence levels. Bioenergetic studies clearly demonstrate UCP function in mitochondria from larval and pupal fat bodies. In non-phosphorylating mitochondria, ZaUCP activity was stimulated by palmitic acid and inhibited by the purine nucleotide GTP. In phosphorylating mitochondria, ZaUCP4 activity decreased the yield of oxidative phosphorylation. ZaUCP4 was immunodetected with antibodies raised against human UCP4 as a single 36-kDa band. A lower expression of ZaUCP4 at the level of mRNA and protein and a decreased ZaUCP4 activity were observed in the Z. atratus pupal fat body compared with the larval fat body. The different expression patterns and activity of ZaUCP4 during the larval-pupal transformation indicates an important physiological role for UCP4 in insect fat body development and function during insect metamorphosis. Copyright © 2012 Elsevier Inc. All rights reserved.

The effect of crataegus fruit extract and some of its flavonoids on mitochondrial oxidative phosphorylation in the heart.

PubMed

Bernatoniene, J; Trumbeckaite, S; Majiene, D; Baniene, R; Baliutyte, G; Savickas, A; Toleikis, A

2009-12-01

Crataegus (Hawthorn) fruit extracts (CE) are widely used for the treatment of various cardiovascular diseases (arrhythmias, heart failure, myocardial weakness, etc). Despite the fact that many of these diseases are associated with disturbances of the mitochondria, no data have been found on the effect of CE on their function. The aim of this study was to perform an oxygraphic investigation of the effect of CE (in concentration range from 70 ng/mL to 13.9 microg/mL of Crataegus phenolic compounds (PC)) and its several pure flavonoids on isolated rat heart mitochondria respiring on pyruvate+malate, succinate and palmitoyl-L-carnitine+malate. CE at doses under 278 ng/mL of PC had no effect on mitochondrial functions. At concentrations from 278 ng/mL to 13.9 microg/mL of PC, CE stimulated State 2 respiration by 11%-34% with all used substrates, and decreased the mitochondrial membrane potential by 1.2-4.4 mV measured with a tetraphenylphosphonium-selective electrode and H2O2 production measured fluorimetrically. Similar uncoupling effects on mitochondrial respiration were observed with several pure CE flavonoids. The highest CE concentration also slightly reduced the maximal ADP-stimulated and uncoupled respiration, which might be due to inhibition of the mitochondrial respiratory chain between flavoprotein and cytochrome c. Whether or not the uncoupling and other effects of CE on mitochondria may be realized in vivo remains to be determined. Copyright (c) 2009 John Wiley & Sons, Ltd.

Thyroid hormone affects secretory activity and uncoupling protein-3 expression in rat harderian gland.

PubMed

Chieffi Baccari, Gabriella; Monteforte, Rossella; de Lange, Pieter; Raucci, Franca; Farina, Paola; Lanni, Antonia

2004-07-01

The effects of T(3) administration on the rat Harderian gland were examined at morphological, biochemical, and molecular levels. T(3) induced hypertrophy of the two cell types (A and B) present in the glandular epithelium. In type A cells, the hypertrophy was mainly due to an increase in the size of the lipid compartment. The acinar lumina were filled with lipoproteic substances, and the cells often showed an olocrine secretory pattern. In type B cells, the hypertrophy largely consisted of a marked proliferation of mitochondria endowed with tightly packed cristae, the mitochondrial number being nearly doubled (from 62 to 101/100 microm(2)). Although the average area of individual mitochondria decreased by about 50%, the total area of the mitochondrial compartment increased by about 80% (from 11 to 19/100 microm(2)). This could be ascribed to T(3)-induced mitochondrial proliferation. The morphological and morphometric data correlated well with our biochemical results, which indicated that mitochondrial respiratory activity is increased in hyperthyroid rats. T(3), by influencing the metabolic function of the mitochondrial compartment, induces lipogenesis and the release of secretory product by type A cells. Mitochondrial uncoupling proteins 2 and 3 were expressed at both mRNA and protein levels in the euthyroid rat Harderian gland. T(3) treatment increased the mRNA levels of both uncoupling protein 2 (UCP2) and UCP3, but the protein level only of UCP3. A possible role for these proteins in the Harderian gland is discussed.

Uncoupling Lipid Metabolism from Inflammation through Fatty Acid Binding Protein-Dependent Expression of UCP2

PubMed Central

Xu, Hongliang; Hertzel, Ann V.; Steen, Kaylee A.; Wang, Qigui; Suttles, Jill

2015-01-01

Chronic inflammation in obese adipose tissue is linked to endoplasmic reticulum (ER) stress and systemic insulin resistance. Targeted deletion of the murine fatty acid binding protein (FABP4/aP2) uncouples obesity from inflammation although the mechanism underlying this finding has remained enigmatic. Here, we show that inhibition or deletion of FABP4/aP2 in macrophages results in increased intracellular free fatty acids (FFAs) and elevated expression of uncoupling protein 2 (UCP2) without concomitant increases in UCP1 or UCP3. Silencing of UCP2 mRNA in FABP4/aP2-deficient macrophages negated the protective effect of FABP loss and increased ER stress in response to palmitate or lipopolysaccharide (LPS). Pharmacologic inhibition of FABP4/aP2 with the FABP inhibitor HTS01037 also upregulated UCP2 and reduced expression of BiP, CHOP, and XBP-1s. Expression of native FABP4/aP2 (but not the non-fatty acid binding mutant R126Q) into FABP4/aP2 null cells reduced UCP2 expression, suggesting that the FABP-FFA equilibrium controls UCP2 expression. FABP4/aP2-deficient macrophages are resistant to LPS-induced mitochondrial dysfunction and exhibit decreased mitochondrial protein carbonylation and UCP2-dependent reduction in intracellular reactive oxygen species. These data demonstrate that FABP4/aP2 directly regulates intracellular FFA levels and indirectly controls macrophage inflammation and ER stress by regulating the expression of UCP2. PMID:25582199

Real-time monitoring of specific oxygen uptake rates of embryonic stem cells in a microfluidic cell culture device.

PubMed

Super, Alexandre; Jaccard, Nicolas; Cardoso Marques, Marco Paulo; Macown, Rhys Jarred; Griffin, Lewis Donald; Veraitch, Farlan Singh; Szita, Nicolas

2016-09-01

Oxygen plays a key role in stem cell biology as a signaling molecule and as an indicator of cell energy metabolism. Quantification of cellular oxygen kinetics, i.e. the determination of specific oxygen uptake rates (sOURs), is routinely used to understand metabolic shifts. However current methods to determine sOUR in adherent cell cultures rely on cell sampling, which impacts on cellular phenotype. We present real-time monitoring of cell growth from phase contrast microscopy images, and of respiration using optical sensors for dissolved oxygen. Time-course data for bulk and peri-cellular oxygen concentrations obtained for Chinese hamster ovary (CHO) and mouse embryonic stem cell (mESCs) cultures successfully demonstrated this non-invasive and label-free approach. Additionally, we confirmed non-invasive detection of cellular responses to rapidly changing culture conditions by exposing the cells to mitochondrial inhibiting and uncoupling agents. For the CHO and mESCs, sOUR values between 8 and 60 amol cell(-1) s(-1) , and 5 and 35 amol cell(-1) s(-1) were obtained, respectively. These values compare favorably with literature data. The capability to monitor oxygen tensions, cell growth, and sOUR, of adherent stem cell cultures, non-invasively and in real time, will be of significant benefit for future studies in stem cell biology and stem cell-based therapies. © 2016 The Authors. Biotechnology Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enforcing dust mass conservation in 3D simulations of tightly coupled grains with the PHANTOM SPH code

NASA Astrophysics Data System (ADS)

Ballabio, G.; Dipierro, G.; Veronesi, B.; Lodato, G.; Hutchison, M.; Laibe, G.; Price, D. J.

2018-06-01

We describe a new implementation of the one-fluid method in the SPH code PHANTOM to simulate the dynamics of dust grains in gas protoplanetary discs. We revise and extend previously developed algorithms by computing the evolution of a new fluid quantity that produces a more accurate and numerically controlled evolution of the dust dynamics. Moreover, by limiting the stopping time of uncoupled grains that violate the assumptions of the terminal velocity approximation, we avoid fatal numerical errors in mass conservation. We test and validate our new algorithm by running 3D SPH simulations of a large range of disc models with tightly and marginally coupled grains.

77 FR 8092 - Airworthiness Directives; Turbomeca S.A. Turboshaft Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-14

...-pressure/low-pressure (HP/LP) pump hydro-mechanical metering units (HMUs) that do not incorporate... uncoupling of the high-pressure/low-pressure (HP/LP) pump hydro-mechanical metering unit (HMU) low-pressure...

Valence State Driven Site Preference in the Quaternary Compound Ca5MgAgGe5: An Electron-Deficient Phase with Optimized Bonding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ponou, Simeon; Lidin, Sven; Zhang, Yuemei

The quaternary phase Ca5Mg0.95Ag1.05(1)Ge5 (3) was synthesized by high-temperature solid-state techniques, and its crystal structure was determined by single-crystal diffraction methods in the orthorhombic space group Pnma – Wyckoff sequence c12 with a = 23.1481(4) Å, b = 4.4736(1) Å, c = 11.0128(2) Å, V = 1140.43(4) Å3, Z = 4. The crystal structure can be described as linear intergrowths of slabs cut from the CaGe (CrB-type) and the CaMGe (TiNiSi-type; M = Mg, Ag) structures. Hence, 3 is a hettotype of the hitherto missing n = 3 member of the structure series with the general formula R2+nT2X2+n, previously describedmore » with n = 1, 2, and 4. The member with n = 3 was predicted in the space group Cmcm – Wyckoff sequence f5c2. The experimental space group Pnma (in the nonstandard setting Pmcn) corresponds to a klassengleiche symmetry reduction of index two of the predicted space group Cmcm. This transition originates from the switching of one Ge and one Ag position in the TiNiSi-related slab, a process that triggers an uncoupling of each of the five 8f sites in Cmcm into two 4c sites in Pnma. The Mg/Ag site preference was investigated using VASP calculations and revealed a remarkable example of an intermetallic compound for which the electrostatic valency principle is a critical structure-directing force. The compound is deficient by one valence electron according to the Zintl concept, but LMTO electronic structure calculations indicate electronic stabilization and overall bonding optimization in the polyanionic network. Other stability factors beyond the Zintl concept that may account for the electronic stabilization are discussed.« less

Climate impacts of parameterized Nordic Sea overflows

NASA Astrophysics Data System (ADS)

Danabasoglu, Gokhan; Large, William G.; Briegleb, Bruce P.

2010-11-01

A new overflow parameterization (OFP) of density-driven flows through ocean ridges via narrow, unresolved channels has been developed and implemented in the ocean component of the Community Climate System Model version 4. It represents exchanges from the Nordic Seas and the Antarctic shelves, associated entrainment, and subsequent injection of overflow product waters into the abyssal basins. We investigate the effects of the parameterized Denmark Strait (DS) and Faroe Bank Channel (FBC) overflows on the ocean circulation, showing their impacts on the Atlantic Meridional Overturning Circulation and the North Atlantic climate. The OFP is based on the Marginal Sea Boundary Condition scheme of Price and Yang (1998), but there are significant differences that are described in detail. Two uncoupled (ocean-only) and two fully coupled simulations are analyzed. Each pair consists of one case with the OFP and a control case without this parameterization. In both uncoupled and coupled experiments, the parameterized DS and FBC source volume transports are within the range of observed estimates. The entrainment volume transports remain lower than observational estimates, leading to lower than observed product volume transports. Due to low entrainment, the product and source water properties are too similar. The DS and FBC overflow temperature and salinity properties are in better agreement with observations in the uncoupled case than in the coupled simulation, likely reflecting surface flux differences. The most significant impact of the OFP is the improved North Atlantic Deep Water penetration depth, leading to a much better comparison with the observational data and significantly reducing the chronic, shallow penetration depth bias in level coordinate models. This improvement is due to the deeper penetration of the southward flowing Deep Western Boundary Current. In comparison with control experiments without the OFP, the abyssal ventilation rates increase in the North Atlantic. In the uncoupled simulation with the OFP, the warm bias of the control simulation in the deep North Atlantic is substantially reduced along with salinity bias reductions in the northern North Atlantic. There are similar but more modest bias reductions in the deep temperature and salinity distributions especially in the northern North Atlantic in the coupled OFP case. In coupled simulations, there are noticeable impacts of the OFP on climate. The sea surface temperatures (SSTs) are warmer by more than 5°C off the North American coast and by more than 1°C in the Nordic Sea with the OFP. The surface heat fluxes mostly act to diminish these SST changes. There are related changes in the sea level pressure, leading to about 15% weaker westerly wind stress in the northern North Atlantic. In response to the warmer Nordic Sea SSTs, there are reductions in the sea ice extent, improving comparisons with observations. Although the OFP cases improve many aspects of the simulations compared to observations, some significant biases remain, more in coupled than in uncoupled simulations.

Fabrication and processing of next-generation oxygen carrier materials for chemical looping combustion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nadarajah, Arunan

Among numerous methods of controlling the global warming effect, Chemical Looping Combustion is known to be the most viable option currently. A key factor to a successful chemical looping process is the presence of highly effective oxygen carriers that enable fuel combustion by going through oxidation and reduction in the presence of air and fuel respectively. In this study, CaMnO 3-δ was used as the base material and doped on the A-site (Sr or La) and B-site (Fe, Ti, Zn and Al) by 10 mol % of dopants. Solid state reaction followed by mechanical extrusion (optimized paste formula) was usedmore » as the preparation method A series of novel doped perovskite-type oxygen carrier particles (Ca xLa (Or Sa) 1-x Mn 1-yByO 3-δ (B-site = Fe, Ti, Al, or Zr)) were synthesized by the proposed extrusion formula. The produced samples were characterized with XRD, SEM, BET and TGA techniques. According to the results obtained from TGA analysis, the oxygen capacity of the samples ranged between 1.2 for CLMZ and 1.75 for CSMF. Reactivity and oxygen uncoupling behaviors of the prepared samples were also evaluated using a fluidized bed chemical looping reactor using methane as the fuel at four different temperatures (800, 850, 900, 950 °C). All of the oxygen carriers showed oxygen uncoupling behavior and they were able to capture and release oxygen. Mass-based conversion of the perovskites was calculated and temperature increase proved to increase the mass-based conversion rate in all of the samples under study. Gas yield was calculated at 950 °C as well, and results showed that CLMZ, CM and CSMF showed 100% gas yields and CLMF and CSMZ showed approximately 85% yield in fluidized bed reactor, which is a high and acceptable quantity. Based on extended reactor tests the modified calcium manganese perovskite structures (CSMF) can be a good candidate for future pilot tests.« less

Study of magnetization switching in coupled magnetic nanostructured systems

NASA Astrophysics Data System (ADS)

Radu, Cosmin

A study of magnetization dynamics experiments in nanostructured materials using the rf susceptibility tunnel diode oscillator (TDO) method is presented along with a extensive theoretical analysis. An original, computer controlled experimental setup that measures the change in susceptibility with the variation in external magnetic field and sample temperature was constructed. The TDO-based experiment design and construction is explained in detail, showing all the elements of originality. This experimental technique has proven reliable for characterizing samples with uncoupled magnetic structure and various magnetic anisotropies like: CrO2, FeCo/IrMn and Co/SiO2 thin films. The TDO was subsequently used to explore the magnetization switching in coupled magnetic systems, like synthetic antiferromagnet (SAF) structures. Magnetoresistive random access memory (MRAM) is an important example of devices where the use of SAF structure is essential. To support the understanding of the SAF magnetic behavior, its configuration and application are reviewed and more details are provided in an appendix. Current problems in increasing the scalability and decreasing the error rate of MRAM devices are closely connected to the switching properties of the SAF structures. Several theoretical studies that were devoted to the understanding of the concepts of SAF critical curve are reviewed. As one can notice, there was no experimental determination of SAF critical curve, due to the difficulties in characterizing a magnetic coupled structure. Depending of the coupling strength between the two ferromagnetic layers, on the SAF critical curve one distinguishes several new features, inexistent in the case of uncoupled systems. Knowing the configuration of the SAF critical curve is of great importance in order to control its switching characteristics. For the first time a method of experimentally recording the critical curve for SAF is proposed in this work. In order to overcome technological limitations, a new way of recording the critical curve by using an additional magnetic bias field was explored. Keywords: magnetization dynamics, magnetic susceptibility, tunnel diode oscillator, critical curve, synthetic antiferromagnet, coupled magnetic structures, MRAM.

Uncoupling primer and releaser responses to pheromone in honey bees

NASA Astrophysics Data System (ADS)

Grozinger, Christina M.; Fischer, Patrick; Hampton, Jacob E.

2007-05-01

Pheromones produce dramatic behavioral and physiological responses in a wide variety of species. Releaser pheromones elicit rapid responses within seconds or minutes, while primer pheromones produce long-term changes which may take days to manifest. Honeybee queen mandibular pheromone (QMP) elicits multiple distinct behavioral and physiological responses in worker bees, as both a releaser and primer, and thus produces responses on vastly different time scales. In this study, we demonstrate that releaser and primer responses to QMP can be uncoupled. First, treatment with the juvenile hormone analog methoprene leaves a releaser response (attraction to QMP) intact, but modulates QMP’s primer effects on sucrose responsiveness. Secondly, two components of QMP (9-ODA and 9-HDA) do not elicit a releaser response (attraction) but are as effective as QMP at modulating a primer response, downregulation of foraging-related brain gene expression. These results suggest that different responses to a single pheromone may be produced via distinct pathways.

The efficiency of cellular energy transduction and its implications for obesity.

PubMed

Harper, Mary-Ellen; Green, Katherine; Brand, Martin D

2008-01-01

We assess the existence, mechanism, and functions of less-than-maximal coupling efficiency of mitochondrial oxidative phosphorylation and its potential as a target for future antiobesity interventions. Coupling efficiency is the proportion of oxygen consumption used to make adenosine triphosphate (ATP) and do useful work. High coupling efficiency may lead to fat deposition; low coupling efficiency to a decrease in fat stores. We review obligatory and facultative energy expenditure and the role of a futile cycle of proton pumping and proton leak across the mitochondrial inner membrane in dissipating energy. Basal proton conductance is catalyzed primarily by the adenine nucleotide translocase but can be mimicked by chemical uncouplers. Inducible proton conductance is catalyzed by specific uncoupling proteins. We discuss the opportunities and pitfalls of targeting these processes as a treatment for obesity by decreasing coupling efficiency and increasing energy expenditure, either directly or through central mechanisms of energy homeostasis.

Longitudinal optical phonon-plasmon coupled modes of degenerate Al-doped ZnO films

NASA Astrophysics Data System (ADS)

Ding, K.; Hu, Q. C.; Lin, W. W.; Huang, J. K.; Huang, F.

2012-07-01

We have investigated the interaction between carriers and polar phonons by using Raman scattering spectroscopy in highly conductive Al-doped ZnO films grown by metalorganic chemical vapor deposition. Different from the longitudinal optical phonon-plasmon coupled modes (LOPPCM) observed in nondegenerate ZnO, an A1(LO)-like mode appears at the low frequency side of the uncoupled A1(LO) mode, and it monotonically shifts to higher frequencies and approaches to the uncoupled A1(LO) mode as Al composition increases. Based on line shape calculations, the A1(LO)-like mode is assigned to the large wave-vector LOPPCM arising from nonconserving scattering dominated by the Al impurity-induced Fröhlich mechanism. Benefiting from the nonmonotonic Al composition dependence of the electron density, it is revealed that the LOPPCM depends mainly on the doping level but not the carrier concentration.

Dynamics of Leading-strand Lesion Skipping by the Replisome

PubMed Central

Yeeles, Joseph T.P.; Marians, Kenneth J.

2013-01-01

SUMMARY The E. coli replisome stalls transiently when it encounters a lesion in the leading-strand template, skipping over the damage by reinitiating replication at a new primer synthesized downstream by the primase. We report here that template unwinding and lagging-strand synthesis continue downstream of the lesion at a reduced rate after replisome stalling, that one replisome is capable of skipping multiple lesions, and that the rate limiting steps of replication restart involve the synthesis and activation of the new primer downstream. We also find little support for the concept that polymerase uncoupling, where extensive lagging-strand synthesis proceeds downstream in the absence of leading-strand synthesis, involves physical separation of the leading-strand polymerase from the replisome. Instead, our data indicate that extensive uncoupled replication likely results from a failure of the leading-strand polymerase still associated with the DNA helicase and the lagging-strand polymerase that are proceeding downstream to reinitiate synthesis. PMID:24268579

Optimum Actuator Selection with a Genetic Algorithm for Aircraft Control

NASA Technical Reports Server (NTRS)

Rogers, James L.

2004-01-01

The placement of actuators on a wing determines the control effectiveness of the airplane. One approach to placement maximizes the moments about the pitch, roll, and yaw axes, while minimizing the coupling. For example, the desired actuators produce a pure roll moment without at the same time causing much pitch or yaw. For a typical wing, there is a large set of candidate locations for placing actuators, resulting in a substantially larger number of combinations to examine in order to find an optimum placement satisfying the mission requirements and mission constraints. A genetic algorithm has been developed for finding the best placement for four actuators to produce an uncoupled pitch moment. The genetic algorithm has been extended to find the minimum number of actuators required to provide uncoupled pitch, roll, and yaw control. A simplified, untapered, unswept wing is the model for each application.

Rat liver uncoupling protein 2: changes induced by a fructose-rich diet.

PubMed

Castro, María C; Massa, María L; Del Zotto, Héctor; Gagliardino, Juan J; Francini, Flavio

2011-10-24

To evaluate the role of uncoupling protein 2 (UCP2) and peroxisome proliferator-activated receptors (PPARs) in the response of liver to glycoxidative stress triggered by administration of a fructose-rich diet (FRD). We assessed blood glucose in the fasting state and after a glucose load (glucose-oxidase method), serum triglyceride (enzymatic measurement), insulin (radioimmunoassay), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels (colorimetric kits) in control and FRD animals. In liver, we measured UCP2, PPARα, PPARδ and PPARγ gene (real-time PCR) and protein (Western blot) expression, fatty acid synthase (FAS) and glycerol-3-phosphate acyltransferase (GPAT) gene expression, as well as triglyceride content. Blood glucose, serum insulin and triglyceride levels, homeostasis model assessment of insulin resistance (HOMA-IR) indexes and impaired glucose tolerance were higher in FRD rats. Whereas UCP2 and PPARδ gene and protein expression increased in these animals; PPARγ levels were lower and those of PPARα remained unchanged. FRD also increased the mRNA expression of PPARδ target genes FAS and GPAT. Our results suggest that a) the increased UCP2 gene and protein expression measured in FRD rats could be part of a compensatory mechanism to reduce reactive oxygen species production induced by the fructose overload, and b) PPARs expression participates actively in the regulation of UCP2 expression, and under the metabolic condition tested, PPARδ played a key role. This knowledge would help to better understand the mechanisms involved in liver adaptation to fructose-induced glycoxidative stress, and to develop appropriate prevention strategies in obesity and type 2 diabetes. Copyright © 2011 Elsevier Inc. All rights reserved.

Impaired Expression of Uncoupling Protein 2 (UCP2) Causes Defective Post-ischemic Angiogenesis in Mice Deficient in AMP-activated Protein Kinase α Subunits

PubMed Central

Xu, Ming-Jiang; Song, Ping; Shirwany, Najeeb; Liang, Bin; Xing, Junjie; Viollet, Benoit; Wang, Xian; Zhu, Yi; Zou, Ming-Hui

2011-01-01

Objective The aim of the present study was to determine whether mitochondrial uncoupling protein (UCP)-2 is required for AMPK-dependent angiogenesis in ischemia in vivo. Methods and Results Angiogenesis was assayed by monitoring endothelial tube formation (a surrogate for angiogenesis) in human umbilical vein endothelial cells (HUVECs), isolated mouse aortic endothelial cells (MAECs), and pulmomary microvascular endothelial cells (PMECs), or in ischemic thigh adductor muscles from wild-type (WT) mice or mice deficient in either AMPKα1 or AMPKα2. AMPK inhibition with pharmacological inhibitor (compound C) or genetic means (transfection of AMPKα-specific siRNA) significantly lowered the tube formation in HUVECs. Consistently, compared with WT mice, tube formation in MAECs isolated from either AMPKα1−/− or AMPKα2−/− mice, which exhibited oxidative stress and reduced expression of UCP2, were significantly impaired. In addition, adenoviral overexpression of UCP2, but not adenoviruses encoding green florescence protein (GFP), normalized tube formation in MAECs from either AMPKα1−/− or AMPKα2−/− mice. Similarly, supplementation with sodium nitroprusside (SNP), a nitric oxide (NO) donor, restored tube formation. Furthermore, ischemia significantly increased angiogenesis, serine 1177 phosphorylation of endothelial NO synthase (eNOS), and UCP2 in ischemic thigh adductor muscles from WT mice, but not from either AMPKα1−/− or AMPKα2−/− mice. Conclusion We conclude that AMPK-dependent UCP2 expression in endothelial cells promotes angiogenesis in vivo. PMID:21597006

Time-lapse microscopy of lung endothelial cells under hypoxia

NASA Astrophysics Data System (ADS)

Mehrvar, Shima; Ghanian, Zahra; Kondouri, Ganesh; Camara, Amadou S.; Ranji, Mahsa

2017-02-01

Objective: This study utilizes fluorescence microscopy to assess the effect of the oxygen tension on the production of reactive oxygen species (ROS) in mitochondria of fetal pulmonary artery endothelial cells (FPAECs). Introduction: Hypoxia is a severe oxygen stress, which mostly causes irreversible injury in lung cells. However, in some studies, it is reported that hypoxia decreases the severity of injuries. In this study, ROS production level was examined in hypoxic FPAECs treated with pentachlorophenol (PCP, uncoupler). This work was accomplished by monitoring and quantifying the changes in the level of the produced ROS in hypoxic cells before and after PCP treatment. Materials and methods: The dynamic of the mitochondrial ROS production in two groups of FPAECs was measured over time using time-lapse microscopy. For the first group, cells were incubated in 3% hypoxic condition for 2 hours and then continuously were exposed to hypoxic condition for imaging as well. For the second group, cells were incubated in normal oxygen condition. Time lapse images of the cells loaded with Mito-SOX (ROS indicator) were acquired, and the red fluorescence intensity profile of the cells was calculated. Changes in the level of the fluorescence intensity profile while they are treated with PCP indicates the dynamics of the ROS level. Results: The intensity profiles of the PCP-treated cells in the first group showed 47% lower ROS production rate than the PCP-treated cells in the second group. Conclusion: Time lapse microscopy revealed that hypoxic cells have lower ROS generation while treated with PCP. Therefore, this result suggests that hypoxia decreased electron transport chain activity in uncoupled chain.

Rotordynamic forces in labyrinth seals: Theory and experiment

NASA Technical Reports Server (NTRS)

Millsaps, Knox T.; Martinez-Sanchez, Manuel

1994-01-01

A theoretical and experimental investigation of the aerodynamic forces generated by a single gland labyrinth seal executing a simultaneous spinning/whirling motion has been conducted. A lumped parameter model for a single gland seal with coupling to an upstream cavity with leakage is developed along with an appropriate solution technique. From this theory, it is shown that the presence of the upstream cavity can, in some cases, augment the cross-stiffness and direct damping by a factor of four. The parameters that govern the coupling are presented along with predictions on their influence. A simple uncoupled model is used to identify the mechanisms responsible for cross force generation. This reduced system is nondimensionalized and the physical significance of the reduced parameters is discussed. Closed form algebraic formulas are given for some simple limiting cases. It is also shown that the total cross-force predicted by the uncoupled model can be represented as the sum of an ideal component due to an inviscid flow with entry swirl and a viscous part due to the change in swirl created by friction inside the gland. The frequency dependent ideal part is solely responsible for the rotordynamic direct damping. The facility designed and built to measure these frequency dependent forces is described. Experimental data confirm the validity and usefulness of this ideal/viscous decomposition. A method for calculating the damping coefficients based on the force decomposition using only the static measurements is presented. Experimental results supporting the predicted cross force augmentation due to the effect of upstream coupling are presented.

A culture system to study oligodendrocyte myelination-processes using engineered nanofibers

PubMed Central

Lee, Seonok; Leach, Michelle K.; Redmond, Stephanie A.; Chong, S.Y. Christin; Mellon, Synthia H.; Tuck, Samuel J.; Feng, Zhang-Qi; Corey, Joseph M.; Chan, Jonah R.

2012-01-01

Current methods for studying central nervous system myelination necessitate permissive axonal substrates conducive for myelin wrapping by oligodendrocytes. We have developed a neuron-free culture system in which electron-spun nanofibers of varying sizes substitute for axons as a substrate for oligodendrocyte myelination, thereby allowing manipulation of the biophysical elements of axonal-oligodendroglial interactions. To investigate axonal regulation of myelination, this system effectively uncouples the role of molecular (inductive) cues from that of biophysical properties of the axon. We use this method to uncover the causation and sufficiency of fiber diameter in the initiation of concentric wrapping by rat oligodendrocytes. We also show that oligodendrocyte precursor cells display sensitivity to the biophysical properties of fiber diameter and initiate membrane ensheathment prior to differentiation. The use of nanofiber scaffolds will enable screening for potential therapeutic agents that promote oligodendrocyte differentiation and myelination as well as provide valuable insight into the processes involved in remyelination. PMID:22796663

A spectral multi-domain technique applied to high-speed chemically reacting flows

NASA Technical Reports Server (NTRS)

Macaraeg, Michele G.; Streett, Craig L.; Hussaini, M. Yousuff

1989-01-01

The first applications of a spectral multidomain method for viscous compressible flow is presented. The method imposes a global flux balance condition at the interface so that high-order continuity of the solution is preserved. The global flux balance is imposed in terms of a spectral integral of the discrete equations across adjoining domains. Since the discretized equations interior to each domain solved are uncoupled from each other, and since the interface relation has a block structure, the solution scheme can be adapted to the particular requirements of each subdomain. The spectral multidomain technique presented is well-suited for the multiple scales associated with the chemically reacting and transition flows in hypersonic research. A nonstaggered multidomain discretization is used for the chemically reacting flow calculation, and the first implementation of a staggered multidomain mesh is presented for accurately solving the stability equation for a viscous compressible fluid.

Time-asymptotic solutions of the Navier-Stokes equation for free shear flows using an alternating-direction implicit method

NASA Technical Reports Server (NTRS)

Rudy, D. H.; Morris, D. J.

1976-01-01

An uncoupled time asymptotic alternating direction implicit method for solving the Navier-Stokes equations was tested on two laminar parallel mixing flows. A constant total temperature was assumed in order to eliminate the need to solve the full energy equation; consequently, static temperature was evaluated by using algebraic relationship. For the mixing of two supersonic streams at a Reynolds number of 1,000, convergent solutions were obtained for a time step 5 times the maximum allowable size for an explicit method. The solution diverged for a time step 10 times the explicit limit. Improved convergence was obtained when upwind differencing was used for convective terms. Larger time steps were not possible with either upwind differencing or the diagonally dominant scheme. Artificial viscosity was added to the continuity equation in order to eliminate divergence for the mixing of a subsonic stream with a supersonic stream at a Reynolds number of 1,000.

Posttraining transcranial magnetic stimulation of striate cortex disrupts consolidation early in visual skill learning.

PubMed

De Weerd, Peter; Reithler, Joel; van de Ven, Vincent; Been, Marin; Jacobs, Christianne; Sack, Alexander T

2012-02-08

Practice-induced improvements in skilled performance reflect "offline " consolidation processes extending beyond daily training sessions. According to visual learning theories, an early, fast learning phase driven by high-level areas is followed by a late, asymptotic learning phase driven by low-level, retinotopic areas when higher resolution is required. Thus, low-level areas would not contribute to learning and offline consolidation until late learning. Recent studies have challenged this notion, demonstrating modified responses to trained stimuli in primary visual cortex (V1) and offline activity after very limited training. However, the behavioral relevance of modified V1 activity for offline consolidation of visual skill memory in V1 after early training sessions remains unclear. Here, we used neuronavigated transcranial magnetic stimulation (TMS) directed to a trained retinotopic V1 location to test for behaviorally relevant consolidation in human low-level visual cortex. Applying TMS to the trained V1 location within 45 min of the first or second training session strongly interfered with learning, as measured by impaired performance the next day. The interference was conditional on task context and occurred only when training in the location targeted by TMS was followed by training in a second location before TMS. In this condition, high-level areas may become coupled to the second location and uncoupled from the previously trained low-level representation, thereby rendering consolidation vulnerable to interference. Our data show that, during the earliest phases of skill learning in the lowest-level visual areas, a behaviorally relevant form of consolidation exists of which the robustness is controlled by high-level, contextual factors.

Mitochondrial uncoupling proteins in unicellular eukaryotes.

PubMed

Jarmuszkiewicz, Wieslawa; Woyda-Ploszczyca, Andrzej; Antos-Krzeminska, Nina; Sluse, Francis E

2010-01-01

Uncoupling proteins (UCPs) are members of the mitochondrial anion carrier protein family that are present in the mitochondrial inner membrane and mediate free fatty acid (FFA)-activated, purine nucleotide (PN)-inhibited proton conductance. Since 1999, the presence of UCPs has been demonstrated in some non-photosynthesising unicellular eukaryotes, including amoeboid and parasite protists, as well as in non-fermentative yeast and filamentous fungi. In the mitochondria of these organisms, UCP activity is revealed upon FFA-induced, PN-inhibited stimulation of resting respiration and a decrease in membrane potential, which are accompanied by a decrease in membranous ubiquinone (Q) reduction level. UCPs in unicellular eukaryotes are able to divert energy from oxidative phosphorylation and thus compete for a proton electrochemical gradient with ATP synthase. Our recent work indicates that membranous Q is a metabolic sensor that might utilise its redox state to release the PN inhibition of UCP-mediated mitochondrial uncoupling under conditions of phosphorylation and resting respiration. The action of reduced Q (QH2) could allow higher or complete activation of UCP. As this regulatory feature was demonstrated for microorganism UCPs (A. castellanii UCP), plant and mammalian UCP1 analogues, and UCP1 in brown adipose tissue, the process could involve all UCPs. Here, we discuss the functional connection and physiological role of UCP and alternative oxidase, two main energy-dissipating systems in the plant-type mitochondrial respiratory chain of unicellular eukaryotes, including the control of cellular energy balance as well as preventive action against the production of reactive oxygen species. Copyright © 2009 Elsevier B.V. All rights reserved.

Simulations of Eurasian winter temperature trends in coupled and uncoupled CFSv2

NASA Astrophysics Data System (ADS)

Collow, Thomas W.; Wang, Wanqiu; Kumar, Arun

2018-01-01

Conflicting results have been presented regarding the link between Arctic sea-ice loss and midlatitude cooling, particularly over Eurasia. This study analyzes uncoupled (atmosphere-only) and coupled (ocean-atmosphere) simulations by the Climate Forecast System, version 2 (CFSv2), to examine this linkage during the Northern Hemisphere winter, focusing on the simulation of the observed surface cooling trend over Eurasia during the last three decades. The uncoupled simulations are Atmospheric Model Intercomparison Project (AMIP) runs forced with mean seasonal cycles of sea surface temperature (SST) and sea ice, using combinations of SST and sea ice from different time periods to assess the role that each plays individually, and to assess the role of atmospheric internal variability. Coupled runs are used to further investigate the role of internal variability via the analysis of initialized predictions and the evolution of the forecast with lead time. The AMIP simulations show a mean warming response over Eurasia due to SST changes, but little response to changes in sea ice. Individual runs simulate cooler periods over Eurasia, and this is shown to be concurrent with a stronger Siberian high and warming over Greenland. No substantial differences in the variability of Eurasian surface temperatures are found between the different model configurations. In the coupled runs, the region of significant warming over Eurasia is small at short leads, but increases at longer leads. It is concluded that, although the models have some capability in highlighting the temperature variability over Eurasia, the observed cooling may still be a consequence of internal variability.

Loss of histaminergic modulation of thermoregulation and energy homeostasis in obese mice.

PubMed

Sethi, J; Sanchez-Alavez, M; Tabarean, I V

2012-08-16

Histamine acts centrally to increase energy expenditure and reduce body weight by mechanisms not fully understood. It has been suggested that in the obese state hypothalamic histamine signaling is altered. Previous studies have also shown that histamine acting in the preoptic area controls thermoregulation. We aimed to study the influence of preoptic histamine on body temperature and energy homeostasis in control and obese mice. Activating histamine receptors in the preoptic area by increasing the concentration of endogenous histamine or by local injection of specific agonists induced an elevation of core body temperature and decreased respiratory exchange ratio (RER). In addition, the food intake was significantly decreased. The hyperthermic effect was associated with a rapid increase in mRNA expression of uncoupling proteins in thermogenic tissues, the most pronounced being that of uncoupling protein (UCP) 1 in brown adipose tissue and of UCP2 in white adipose tissue. In diet-induced obese mice histamine had much diminished hyperthermic effects as well as reduced effect on RER. Similarly, the ability of preoptic histamine signaling to increase the expression of uncoupling proteins was abolished. We also found that the expression of mRNA encoding the H1 receptor subtype in the preoptic area was significantly lower in obese animals. These results indicate that histamine signaling in the preoptic area modulates energy homeostasis by regulating body temperature, metabolic parameters and food intake and that the obese state is associated with a decrease in neurotransmitter's influence. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

Complementary Roles of Estrogen-Related Receptors in Brown Adipocyte Thermogenic Function

PubMed Central

Gantner, Marin L.; Hazen, Bethany C.; Eury, Elodie; Brown, Erin L.

2016-01-01

Brown adipose tissue (BAT) thermogenesis relies on a high abundance of mitochondria and the unique expression of the mitochondrial Uncoupling Protein 1 (UCP1), which uncouples substrate oxidation from ATP synthesis. Adrenergic stimulation of brown adipocytes activates UCP1-mediated thermogenesis; it also induces the expression of Ucp1 and other genes important for thermogenesis, thereby endowing adipocytes with higher oxidative and uncoupling capacities. Adipocyte mitochondrial biogenesis and oxidative capacity are controlled by multiple transcription factors, including the estrogen-related receptor (ERR)α. Whole-body ERRα knockout mice show decreased BAT mitochondrial content and oxidative function but normal induction of Ucp1 in response to cold. In addition to ERRα, brown adipocytes express ERRβ and ERRγ, 2 nuclear receptors that are highly similar to ERRα and whose function in adipocytes is largely unknown. To gain insights into the roles of all 3 ERRs, we assessed mitochondrial function and adrenergic responses in primary brown adipocytes lacking combinations of ERRs. We show that adipocytes lacking just ERRα, the most abundant ERR, show only mild mitochondrial defects. Adipocytes lacking ERRβ and ERRγ also show just mild defects. In contrast, adipocytes lacking all 3 ERRs have severe reductions in mitochondrial content and oxidative capacity. Moreover, adipocytes lacking all 3 ERRs have defects in the transcriptional and metabolic response to adrenergic stimulation, suggesting a wider role of ERRs in BAT function than previously appreciated. Our study shows that ERRs have a great capacity to compensate for each other in protecting mitochondrial function and the metabolic response to adrenergic signaling, processes vital to BAT function. PMID:27763777

Resveratrol up-regulates hepatic uncoupling protein 2 and prevents development of nonalcoholic fatty liver disease in rats fed a high-fat diet.

PubMed

Poulsen, Morten Møller; Larsen, Jens Ø; Hamilton-Dutoit, Stephen; Clasen, Berthil F; Jessen, Niels; Paulsen, Søren K; Kjær, Thomas N; Richelsen, Bjørn; Pedersen, Steen B

2012-09-01

Obesity is associated with a markedly increased risk of nonalcoholic fatty liver disease. The anti-inflammatory polyphenol resveratrol possess promising properties in preventing this metabolic condition by dampening the pathological inflammatory reaction in the hepatic tissue. However, in the current study, we hypothesize that the beneficial effect of resveratrol is not solely attributable to its anti-inflammatory potential. Eight-week-old male Wistar rats were randomly distributed into 3 groups of 12 animals each: control diet (C), high-fat diet (HF), and HF supplemented with 100 mg resveratrol daily (HFR). After 8 weeks of dietary treatment, the rats were euthanized and relevant tissues were prepared for subsequent analysis. Resveratrol prevented the high fat-induced steatosis assessed by semiquantitative grading, which furthermore corresponded with a complete normalization of the hepatic triglyceride content (P < .001), despite no change in total body fat. In HFR, the hepatic uncoupling protein 2 expression was significantly increased by 76% and 298% as compared with HF and C, respectively. Moreover, the hepatic mitochondria content in HFR was significantly higher as compared with both C and HF (P < .001 and P = .004, respectively). We found no signs of hepatic inflammation, hereby demonstrating that resveratrol protects against fatty liver disease independently of its proposed anti-inflammatory potential. Our data might indicate that an increased number of mitochondria and, particularly, an increase in hepatic uncoupling protein 2 expression are involved in normalizing the hepatic fat content due to resveratrol supplementation in rodents fed a high-fat diet. Copyright © 2012 Elsevier Inc. All rights reserved.

Control of Mitochondrial pH by Uncoupling Protein 4 in Astrocytes Promotes Neuronal Survival*

PubMed Central

Perreten Lambert, Hélène; Zenger, Manuel; Azarias, Guillaume; Chatton, Jean-Yves; Magistretti, Pierre J.; Lengacher, Sylvain

2014-01-01

Brain activity is energetically costly and requires a steady and highly regulated flow of energy equivalents between neural cells. It is believed that a substantial share of cerebral glucose, the major source of energy of the brain, will preferentially be metabolized in astrocytes via aerobic glycolysis. The aim of this study was to evaluate whether uncoupling proteins (UCPs), located in the inner membrane of mitochondria, play a role in setting up the metabolic response pattern of astrocytes. UCPs are believed to mediate the transmembrane transfer of protons, resulting in the uncoupling of oxidative phosphorylation from ATP production. UCPs are therefore potentially important regulators of energy fluxes. The main UCP isoforms expressed in the brain are UCP2, UCP4, and UCP5. We examined in particular the role of UCP4 in neuron-astrocyte metabolic coupling and measured a range of functional metabolic parameters including mitochondrial electrical potential and pH, reactive oxygen species production, NAD/NADH ratio, ATP/ADP ratio, CO2 and lactate production, and oxygen consumption rate. In brief, we found that UCP4 regulates the intramitochondrial pH of astrocytes, which acidifies as a consequence of glutamate uptake, with the main consequence of reducing efficiency of mitochondrial ATP production. The diminished ATP production is effectively compensated by enhancement of glycolysis. This nonoxidative production of energy is not associated with deleterious H2O2 production. We show that astrocytes expressing more UCP4 produced more lactate, which is used as an energy source by neurons, and had the ability to enhance neuronal survival. PMID:25237189

Uncoupling protein-2 deficient mice are not protected against warm ischemia/reperfusion injury of the liver.

PubMed

Le Minh, Khoi; Berger, Andreas; Eipel, Christian; Kuhla, Angela; Minor, Thomas; Stegemann, Judith; Vollmar, Brigitte

2011-12-01

Uncoupling protein-2 (UCP2) might play an important role in mediating ischemia/reperfusion (I/R) injury due to its function in uncoupling of oxidative phosphorylation and in the proton leak-associated increase of reactive oxygen species (ROS) production. The aim of this study was to elucidate the role of UCP2 in hepatic I/R injury. UCP2 wild type and UCP2 deficient mice were subjected to I/R of the left liver lobe. Sham-operated animals without I/R served as controls. Intravital fluorescence microscopy was used for assessing postischemic microcirculatory dysfunction. Indicators of hepatic inflammatory response, oxidative stress, and bioenergetic status as well as histomorphology were investigated. Under sham conditions UCP2-/-mice presented slightly but not significantly higher levels of hepatic ATP and energy charge than wild type mice. In addition, they exhibited higher systemic IL-6 levels and intrahepatic leukocyte adherence. After exposure to I/R, the extent of reperfusion injury did not differ between UCP2+/+ and UCP2-/-mice, as indicated by a comparable loss of sinusoidal perfusion, hepatic ATP, and energy charge levels, as well as rise of transaminases and disintegration of liver structures. Intrahepatic leukocyte adherence and plasma IL-6 levels of postischemic UCP2-/-mice still exceeded those of UCP2+/+mice. UCP2 appears to be of minor relevance for the manifestation and extent of postischemic reperfusion injury in nondiseased livers with the increased ATP availability being counteracted by the higher pro-inflammatory IL-6 levels in UCP2 deficient mice. Copyright © 2011 Elsevier Inc. All rights reserved.

Respiration, oxidative phosphorylation, and uncoupling protein in Candida albicans.

PubMed

Cavalheiro, R A; Fortes, F; Borecký, J; Faustinoni, V C; Schreiber, A Z; Vercesi, A E

2004-10-01

The respiration, membrane potential (Deltapsi), and oxidative phosphorylation of mitochondria in situ were determined in spheroplasts obtained from Candida albicans control strain ATCC 90028 by lyticase treatment. Mitochondria in situ were able to phosphorylate externally added ADP (200 microM) in the presence of 0.05% BSA. Mitochondria in situ generated and sustained stable mitochondrial Deltapsi respiring on 5 mM NAD-linked substrates, 5 mM succinate, or 100 microM N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride plus 1 mM ascorbate. Rotenone (4 microM) inhibited respiration by 30% and 2 micro M antimycin A or myxothiazole and 1 mM cyanide inhibited it by 85%. Cyanide-insensitive respiration was partially blocked by 2 mM benzohydroxamic acid, suggesting the presence of an alternative oxidase. Candida albicans mitochondria in situ presented a carboxyatractyloside-insensitive increase of Deltapsi induced by 5 mM ATP and 0.5% BSA, and Deltapsi decrease induced by 10 microM linoleic acid, both suggesting the existence of an uncoupling protein. The presence of this protein was subsequently confirmed by immunodetection and respiration experiments with isolated mitochondria. In conclusion, Candida albicans ATCC 90028 possesses an alternative electron transfer chain and alternative oxidase, both absent in animal cells. These pathways can be exceptional targets for the design of new chemotherapeutic agents. Blockage of these respiratory pathways together with inhibition of the uncoupling protein (another potential target for drug design) could lead to increased production of reactive oxygen species, dysfunction of Candida mitochondria, and possibly to oxidative cell death.

Uncoupling oxidative phosphorylation with 2,4-dinitrophenol promotes development of the adhesion phenotype.

PubMed

Shavell, Valerie I; Fletcher, Nicole M; Jiang, Zhong L; Saed, Ghassan M; Diamond, Michael P

2012-03-01

To determine the effect of uncoupling oxidative phosphorylation with 2,4-dinitrophenol (DNP) on adhesion phenotype development. Prospective experimental study. Academic medical center. Women undergoing laparotomy for pelvic pain from whom normal peritoneum and adhesions were excised to create primary cultures of normal peritoneal and adhesion fibroblasts. Treatment of normal peritoneal and adhesion fibroblasts isolated from the same patient(s) with or without 0.2 mM DNP for 24 hours. Evaluation of adhesion phenotype markers type I collagen, vascular endothelial growth factor (VEGF), and hypoxia-inducible factor (HIF)-1α. In agreement with prior findings, adhesion fibroblasts exhibited significantly higher basal levels of type I collagen, VEGF, and HIF-1α compared with normal peritoneal fibroblasts. Treatment of normal peritoneal fibroblasts with DNP resulted in significant increases in type I collagen (10.2 ± 1.4 vs. 18.4 ± 1.9 fg/μg RNA) and VEGF (8.2 ± 1.1 vs. 13.7 ± 0.4 fg/μg RNA) over baseline. HIF-1α levels did not increase when normal peritoneal fibroblasts were treated with DNP. The adhesion phenotype, which is normally expressed in response to hypoxia, is reproduced in a normoxic environment by uncoupling oxidative phosphorylation with DNP, as evidenced by an increase in type I collagen and VEGF. Acquisition of the adhesion phenotype was via a mechanism distinct from up-regulation of HIF-1α. These observations are consistent with the hypothesis that the adhesion phenotype represents a state of intracellular metabolic depletion. Copyright © 2012 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Uncoupling protein homologs may provide a link between mitochondria, metabolism and lifespan

PubMed Central

Wolkow, Catherine A.; Iser, Wendy B.

2008-01-01

Uncoupling proteins (UCPs), which dissipate the mitochondrial proton gradient, have the ability to decouple mitochodrial respiration from ATP production. Since mitochondrial electron transport is a major source of free radical production, it is possible that UCP activity might impact free radical production. Free radicals can react with and damage cellular proteins, DNA and lipids. Accumulated damage from oxidative stress is believed to be a major contributor to cellular decline during aging. If UCP function were to impact mitochondrial free radical production, then one would expect to find a link between UCP activity and aging. This theory has recently been tested in a handful of organisms whose genomes contain UCP1 homologs. Interestingly, these experiments indicate that UCP homologs can affect lifespan, although they do not support a simple relationship between UCP activity and aging. Instead, UCP-like proteins appear to have a variety of effects on lifespan, and on pathways implicated in lifespan regulation. One possible explanation for this complex picture is that UCP homologs may have tissue-specific effects that complicate their effects on aging. Furthermore, the functional analysis of UCP1 homologs is incomplete. Thus, these proteins may perform functions in addition to, or instead of, mitochondrial uncoupling. Although these studies have not revealed a clear picture of UCP effects on aging, they have contributed to the growing knowledge base for these interesting proteins. Future biochemical and genetic investigation of UCP-like proteins will do much to clarify their functions and to identify the regulatory networks in which they are involved. PMID:16707280

The genetic association study between polymorphisms in uncoupling protein 2 and uncoupling protein 3 and metabolic data in dogs.

PubMed

Udagawa, Chihiro; Tada, Naomi; Asano, Junzo; Ishioka, Katsumi; Ochiai, Kazuhiko; Bonkobara, Makoto; Tsuchida, Shuichi; Omi, Toshinori

2014-12-11

The uncoupling proteins (UCPs) in the mitochondrial inner membrane are members of the mitochondrial anion carrier protein family that play an important role in energy homeostasis. Genetic association studies have shown that human UCP2 and UCP3 variants (SNPs and indels) are associated with obesity, insulin resistance, type 2 diabetes mellitus, and metabolic syndrome. The aim of this study was to examine the genetic association between polymorphisms in UCP2 and UCP3 and metabolic data in dogs. We identified 10 SNPs (9 intronic and 1 exonic) and 4 indels (intronic) in UCP2, and 13 SNPs (11 intronic and 2 exonic) and one indel (exonic) in UCP3, by DNA sequence analysis of 11 different dog breeds (n=119). An association study between these UCP2 and UCP3 variants and the biochemical parameters of glucose, total cholesterol, lactate dehydrogenase and triglyceride in Labrador Retrievers (n=50) showed that none of the UCP2 polymorphisms were significantly associated with the levels of these parameters. However, four UCP3 SNPs (intron 1) were significantly associated with total cholesterol levels. In addition, the allele frequencies of two of the four SNPs associated with higher total cholesterol levels in a breed that is susceptible to hypercholesterolemia (Shetland Sheepdogs, n=30), compared with the control breed (Shiba, n=30). The results obtained from a limited number of individuals suggest that the UCP3 gene in dogs may be associated with total cholesterol levels. The examination of larger sample sizes and further analysis will lead to increased precision of these results.

Uncoupling of Secretion From Growth in Some Hormone Secretory Tissues

PubMed Central

2014-01-01

Context: Most syndromes with benign primary excess of a hormone show positive coupling of hormone secretion to size or proliferation in the affected hormone secretory tissue. Syndromes that lack this coupling seem rare and have not been examined for unifying features among each other. Evidence Acquisition: Selected clinical and basic features were analyzed from original reports and reviews. We examined indices of excess secretion of a hormone and indices of size of secretory tissue within the following three syndromes, each suggestive of uncoupling between these two indices: familial hypocalciuric hypercalcemia, congenital diazoxide-resistant hyperinsulinism, and congenital primary hyperaldosteronism type III (with G151E mutation of the KCNJ5 gene). Evidence Synthesis: Some unifying features among the three syndromes were different from features present among common tumors secreting the same hormone. The unifying and distinguishing features included: 1) expression of hormone excess as early as the first days of life; 2) normal size of tissue that oversecretes a hormone; 3) diffuse histologic expression in the hormonal tissue; 4) resistance to treatment by subtotal ablation of the hormone-secreting tissue; 5) causation by a germline mutation; 6) low potential of the same mutation to cause a tumor by somatic mutation; and 7) expression of the mutated molecule in a pathway between sensing of a serum metabolite and secretion of hormone regulating that metabolite. Conclusion: Some shared clinical and basic features of uncoupling of secretion from size in a hormonal tissue characterize three uncommon states of hormone excess. These features differ importantly from features of common hormonal neoplasm of that tissue. PMID:25004249

Plasma Amino Acids Stimulate Uncoupled Respiration of Muscle Subsarcolemmal Mitochondria in Lean but Not Obese Humans.

PubMed

Kras, Katon A; Hoffman, Nyssa; Roust, Lori R; Patel, Shivam H; Carroll, Chad C; Katsanos, Christos S

2017-12-01

Obesity is associated with mitochondrial dysfunction in skeletal muscle. Increasing the plasma amino acid (AA) concentrations stimulates mitochondrial adenosine triphosphate (ATP) production in lean individuals. To determine whether acute elevation in plasma AAs enhances muscle mitochondrial respiration and ATP production in subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria in obese adults. Assessment of SS and IMF mitochondrial function during saline (i.e., control) and AA infusions. Eligible participants were healthy lean (body mass index, <25 kg/m2; age, 37 ± 3 years; n = 10) and obese (body mass index >30 kg/m2; age 35 ± 3 years; n = 11) subjects. Single trial of saline infusion followed by AA infusion. SS and IMF mitochondria were isolated from muscle biopsies collected at the end of the saline and AA infusions. Mitochondrial respiration and ATP production. AA infusion increased adenosine 5'-diphosphate (ADP)-stimulated respiration and ATP production rates of SS mitochondria in the lean (P < 0.05), but not obese, subjects. Furthermore, AA infusion increased the uncoupled (i.e., non-ADP-stimulated) respiration of SS mitochondria in the lean subjects only (P < 0.05). AA infusion had no effect on any of these parameters in IMF mitochondria in either lean or obese subjects (P > 0.05). Increasing the plasma AA concentrations enhances the capacity for respiration and ATP production of muscle SS, but not IMF, mitochondria in lean individuals, in parallel with increases in uncoupled respiration. However, neither of these parameters increases in muscle SS or IMF mitochondria in obese individuals. Copyright © 2017 Endocrine Society

An evaluation of upper-body muscle activation during coupled and uncoupled instability resistance training.

PubMed

Campbell, Brian M; Kutz, Matt R; Morgan, Amy L; Fullenkamp, Adam M; Ballenger, Ryan

2014-07-01

Recently, there has been a growth in the popularity of resistance exercises performed on unstable surfaces. However, the relationship between unstable surface training and load coupling on muscle activation is unclear. The purpose of this study was to evaluate changes in muscle activation during a barbell (BB) (coupled) and dumbbell (DB) (uncoupled) chest press exercise performed on an unstable surface. The 3 specific chest press conditions included 50% 1 repetition maximum (RM) with BB (50% BB), 50% 1RM with DBs (50% DB), and 25% 1RM with DBs (25% DB). Ten male subjects participated in the study (age, 23.9 ± 2.6 years; body weight, 82.8 ± 10.2 kg). During testing, mean electromyographic activity was assessed for pectoralis major (PM), triceps brachii, anterior deltoid (AD), and rectus abdominis (RA) and was presented as a percent change across the lifting conditions. It was observed that muscle activation increased by 15% in both the PM and RA from the 50% BB condition to the 50% DB condition. Also, the greatest percent difference in muscle activation between the 50 and 25% DB conditions occurred for PM and AD (+54% during 50% DB). These results suggest that demands on the core musculature to provide stability are increased with the use of DBs (uncoupled) as opposed to a BB (coupled). Where instability training provides a sufficient hypertrophy stimulus in prime mover muscle groups, there may be the added benefit of core stability training. Specifically, this type of training may benefit both untrained persons and those engaged in active rehabilitation.

Adipocyte Browning and Higher Mitochondrial Function in Periadrenal But Not SC Fat in Pheochromocytoma.

PubMed

Vergnes, Laurent; Davies, Graeme R; Lin, Jason Y; Yeh, Michael W; Livhits, Masha J; Harari, Avital; Symonds, Michael E; Sacks, Harold S; Reue, Karen

2016-11-01

Patients with pheochromocytoma (pheo) show presence of multilocular adipocytes that express uncoupling protein 1 within periadrenal (pADR) and omental (OME) fat depots. It has been hypothesized that this is due to adrenergic stimulation by catecholamines produced by the pheo tumors. To characterize the prevalence and respiratory activity of brown-like adipocytes within pADR, OME, and SC fat depots in human adult pheo patients. This was an observational cohort study. The study took place in a university hospital. We studied 46 patients who underwent surgery for benign adrenal tumors (21 pheos and 25 controls with adrenocortical adenomas). We characterized adipocyte browning in pADR, SC, and OME fat depots for histological and immunohistological features, mitochondrial respiration rate, and gene expression. We also determined circulating levels of catecholamines and other browning-related hormones. Eleven of 21 pheo pADR adipose samples, but only one of 25 pADR samples from control patients exhibited multilocular adipocytes. The pADR browning phenotype was associated with higher plasma catecholamines and raised uncoupling protein 1. Mitochondria from multilocular pADR fat of pheo patients exhibited increased rates of coupled and uncoupled respiration. Global gene expression analysis in pADR fat revealed enrichment in β-oxidation genes in pheo patients with multilocular adipocytes. No SC or OME fat depots exhibited aspects of browning. Browning of the pADR depot occurred in half of pheo patients and was associated with increased catecholamines and mitochondrial activity. No browning was detected in other fat depots, suggesting that other factors are required to promote browning in these depots.

Ascorbic Acid Prevents VEGF-induced Increases in Endothelial Barrier Permeability

PubMed Central

Ulker, Esad; Parker, William H.; Raj, Amita; Qu, Zhi-chao; May, James M.

2015-01-01

Vascular endothelial growth factor (VEGF) increases endothelial barrier permeability, an effect that may contribute to macular edema in diabetic retinopathy. Since vitamin C, or ascorbic acid, can tighten the endothelial permeability barrier, we examined whether it could prevent the increase in permeability due to VEGF in human umbilical vein endothelial cells (HUVECs). As previously observed, VEGF increased HUVEC permeability to radiolabeled inulin within 60 min in a concentration-dependent manner. Loading the cells with increasing concentrations of ascorbate progressively prevented the leakage caused by 100 ng/ml VEGF, with a significant inhibition at 13 μM and complete inhibition at 50 μM. Loading cells with 100 μM ascorbate also decreased basal generation of reactive oxygen species and prevented the increase caused by both 100 ng/ml VEGF. VEGF treatment decreased intracellular ascorbate by 25%, thus linking ascorbate oxidation to its prevention of VEGF-induced barrier leakage. The latter was blocked by treating the cells with 60 μM L-NAME (but not D-NAME) as well as by 30 μM sepiapterin, a precursor of tetrahydrobiopterin that is required for proper function of endothelial nitric oxide synthase (eNOS). These findings suggest that VEGF-induced barrier leakage uncouples eNOS. Ascorbate inhibition of the VEGF effect could thus be due either to scavenging superoxide or to peroxynitrite generated by the uncoupled eNOS, or more likely to its ability to recycle tetrahydrobiopterin, thus avoiding enzyme uncoupling in the first place. Ascorbate prevention of VEGF-induced increases in endothelial permeability opens the possibility that its repletion could benefit diabetic macular edema. PMID:26590088

Effect of (+)-usnic acid on mitochondrial functions as measured by mitochondria-specific oligonucleotide microarray in liver of B6C3F1 mice.

PubMed

Joseph, Ajay; Lee, Taewon; Moland, Carrie L; Branham, William S; Fuscoe, James C; Leakey, Julian E A; Allaben, William T; Lewis, Sherry M; Ali, Akhtar A; Desai, Varsha G

2009-04-01

Usnic acid is a lichen metabolite used as a weight-loss dietary supplement due to its uncoupling action on mitochondria. However, its use has been associated with severe liver disorders in some individuals. Animal studies conducted thus far evaluated the effects of usnic acid on mitochondria primarily by measuring the rate of oxygen consumption and/or ATP generation. To obtain further insight into usnic acid-mediated effects on mitochondria, we examined the expression levels of 542 genes associated with mitochondrial structure and functions in liver of B6C3F(1) female mice using a mitochondria-specific microarray. Beginning at 8 weeks of age, mice received usnic acid at 0, 60, 180, and 600 ppm in ground, irradiated 5LG6 diet for 14 days. Microarray analysis showed a significant effect of usnic acid on the expression of several genes only at the highest dose of 600 ppm. A prominent finding of the study was a significant induction of genes associated with complexes I through IV of the electron transport chain. Moreover, several genes involved in fatty acid oxidation, the Krebs cycle, apoptosis, and membrane transporters were over-expressed. Usnic acid is a lipophilic weak acid that can diffuse through mitochondrial membranes and cause a proton leak (uncoupling). The up-regulation of complexes I-IV may be a compensatory mechanism to maintain the proton gradient across the mitochondrial inner membrane. In addition, induction of fatty acid oxidation and the Krebs cycle may be an adaptive response to uncoupling of mitochondria.

Astrocyte uncoupling as a cause of human temporal lobe epilepsy.

PubMed

Bedner, Peter; Dupper, Alexander; Hüttmann, Kerstin; Müller, Julia; Herde, Michel K; Dublin, Pavel; Deshpande, Tushar; Schramm, Johannes; Häussler, Ute; Haas, Carola A; Henneberger, Christian; Theis, Martin; Steinhäuser, Christian

2015-05-01

Glial cells are now recognized as active communication partners in the central nervous system, and this new perspective has rekindled the question of their role in pathology. In the present study we analysed functional properties of astrocytes in hippocampal specimens from patients with mesial temporal lobe epilepsy without (n = 44) and with sclerosis (n = 75) combining patch clamp recording, K(+) concentration analysis, electroencephalography/video-monitoring, and fate mapping analysis. We found that the hippocampus of patients with mesial temporal lobe epilepsy with sclerosis is completely devoid of bona fide astrocytes and gap junction coupling, whereas coupled astrocytes were abundantly present in non-sclerotic specimens. To decide whether these glial changes represent cause or effect of mesial temporal lobe epilepsy with sclerosis, we developed a mouse model that reproduced key features of human mesial temporal lobe epilepsy with sclerosis. In this model, uncoupling impaired K(+) buffering and temporally preceded apoptotic neuronal death and the generation of spontaneous seizures. Uncoupling was induced through intraperitoneal injection of lipopolysaccharide, prevented in Toll-like receptor4 knockout mice and reproduced in situ through acute cytokine or lipopolysaccharide incubation. Fate mapping confirmed that in the course of mesial temporal lobe epilepsy with sclerosis, astrocytes acquire an atypical functional phenotype and lose coupling. These data suggest that astrocyte dysfunction might be a prime cause of mesial temporal lobe epilepsy with sclerosis and identify novel targets for anti-epileptogenic therapeutic intervention. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Differential effects of temperature on reactive oxygen/nitrogen species production in rat pachytene spermatocytes and round spermatids.

PubMed

Pino, José A; Osses, Nelson; Oyarzún, Daniela; Farías, Jorge G; Moreno, Ricardo D; Reyes, Juan G

2013-02-01

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) like superoxide and nitric oxide are produced by testis and spermatogenic cells in response to heat stress. However, the magnitude and mechanisms of this production in spermatogenic cells have not been described. In this work, we evaluated ROS/RNS production, its pharmacology, mitochondrial oxidative metabolism, membrane potential and antioxidant capacity at different temperatures in isolated rat pachytene spermatocytes and round spermatids. Our results showed an increment in ROS/RNS production by pachytene spermatocytes when increasing the temperature to 40 °C. Instead, ROS/RNS production by round spermatids did not change at temperatures higher than 33 °C. ROS/RNS production was sensitive to NADPH oxidase inhibitor diphenylene iodonium or the mitochondrial complex I inhibitor rotenone. No additive effects were observed for these two compounds. Our results suggest an important mitochondrial ROS/RNS production in spermatogenic cells. Oligomycin-insensitive oxygen consumption (uncoupled oxygen consumption) increased with temperature and was significantly larger in round spermatids than pachytene spermatocytes, indicating a likely round spermatid mitochondrial uncoupling at high temperatures. A similar conclusion can be reached by measuring the mitochondrial membrane potential using rhodamine 123 fluorescence in permeabilized cells or JC-1 fluorescence in intact cells. The antioxidant capacity was higher in round spermatids than pachytene spermatocytes at 40 °C. Our results strongly suggest that at high temperatures (40 °C) pachytene spermatocytes are more susceptible to oxidative stress, but round spermatids are more protected because of a temperature-induced mitochondrial uncoupling together with a larger antioxidant capacity.

Pig has no uncoupling protein 1.

PubMed

Hou, Lianjie; Shi, Jia; Cao, Lingbo; Xu, Guli; Hu, Chingyuan; Wang, Chong

2017-06-10

Brown adipose tissue (BAT) is critical for mammal's survival in the cold environment. Uncoupling protein 1 (UCP1) is responsible for the non-shivering thermogenesis in the BAT. Pig is important economically as a meat-producing livestock. However, whether BAT or more precisely UCP1 protein exists in pig remains a controversy. The objective of this study was to ascertain whether pig has UCP1 protein. In this study, we used rapid amplification of cDNA ends (RACE) technique to obtain the UCP1 mRNA 3' end sequence, confirmed only exons 1 and 2 of the UCP1 gene are transcribed in the pig. Then we cloned the pig UCP1 gene exons 1 and 2, and expressed the UCP1 protein from the truncated pig gene using E. coli BL21. We used the expressed pig UCP1 protein as antigen for antibody production in a rabbit. We could not detect any UCP1 protein expression in different pig adipose tissues by the specific pig UCP1 antibody, while our antibody can detect the cloned pig UCP1 as well as the mice adipose UCP1 protein. This result shows although exons 1 and 2 of the pig UCP1 gene were transcribed but not translated in the pig adipose tissue. Furthermore, we detected no uncoupled respiration in the isolated pig adipocytes. Thus, these results unequivocally demonstrate that pig has no UCP1 protein. Our results have resolved the controversy of whether pigs have the brown adipose tissue. Copyright © 2017 Elsevier Inc. All rights reserved.

Suppression of injuries caused by a lytic RNA virus (mengovirus) and their uncoupling from viral reproduction by mutual cell/virus disarmament.

PubMed

Mikitas, Olga V; Ivin, Yuri Y; Golyshev, Sergey A; Povarova, Natalia V; Galkina, Svetlana I; Pletjushkina, Olga Y; Nadezhdina, Elena S; Gmyl, Anatoly P; Agol, Vadim I

2012-05-01

Viruses often elicit cell injury (cytopathic effect [CPE]), a major cause of viral diseases. CPE is usually considered to be a prerequisite for and/or consequence of efficient viral growth. Recently, we proposed that viral CPE may largely be due to host defensive and viral antidefensive activities. This study aimed to check the validity of this proposal by using as a model HeLa cells infected with mengovirus (MV). As we showed previously, infection of these cells with wild-type MV resulted in necrosis, whereas a mutant with incapacitated antidefensive ("security") viral leader (L) protein induced apoptosis. Here, we showed that several major morphological and biochemical signs of CPE (e.g., alterations in cellular and nuclear shape, plasma membrane, cytoskeleton, chromatin, and metabolic activity) in cells infected with L(-) mutants in the presence of an apoptosis inhibitor were strongly suppressed or delayed for long after completion of viral reproduction. These facts demonstrate that the efficient reproduction of a lytic virus may not directly require development of at least some pathological alterations normally accompanying infection. They also imply that L protein is involved in the control of many apparently unrelated functions. The results also suggest that the virus-activated program with competing necrotic and apoptotic branches is host encoded, with the choice between apoptosis and necrosis depending on a variety of intrinsic and extrinsic conditions. Implementation of this defensive suicidal program could be uncoupled from the viral reproduction. The possibility of such uncoupling has significant implications for the pathogenesis and treatment of viral diseases.

Suppression of Injuries Caused by a Lytic RNA Virus (Mengovirus) and Their Uncoupling from Viral Reproduction by Mutual Cell/Virus Disarmament

PubMed Central

Mikitas, Olga V.; Ivin, Yuri Y.; Golyshev, Sergey A.; Povarova, Natalia V.; Galkina, Svetlana I.; Pletjushkina, Olga Y.; Nadezhdina, Elena S.; Gmyl, Anatoly P.

2012-01-01

Viruses often elicit cell injury (cytopathic effect [CPE]), a major cause of viral diseases. CPE is usually considered to be a prerequisite for and/or consequence of efficient viral growth. Recently, we proposed that viral CPE may largely be due to host defensive and viral antidefensive activities. This study aimed to check the validity of this proposal by using as a model HeLa cells infected with mengovirus (MV). As we showed previously, infection of these cells with wild-type MV resulted in necrosis, whereas a mutant with incapacitated antidefensive (“security”) viral leader (L) protein induced apoptosis. Here, we showed that several major morphological and biochemical signs of CPE (e.g., alterations in cellular and nuclear shape, plasma membrane, cytoskeleton, chromatin, and metabolic activity) in cells infected with L− mutants in the presence of an apoptosis inhibitor were strongly suppressed or delayed for long after completion of viral reproduction. These facts demonstrate that the efficient reproduction of a lytic virus may not directly require development of at least some pathological alterations normally accompanying infection. They also imply that L protein is involved in the control of many apparently unrelated functions. The results also suggest that the virus-activated program with competing necrotic and apoptotic branches is host encoded, with the choice between apoptosis and necrosis depending on a variety of intrinsic and extrinsic conditions. Implementation of this defensive suicidal program could be uncoupled from the viral reproduction. The possibility of such uncoupling has significant implications for the pathogenesis and treatment of viral diseases. PMID:22438537

Brown adipose tissue dynamics in wild-type and UCP1-knockout mice: in vivo insights with magnetic resonance[S

PubMed Central

Grimpo, Kirsten; Völker, Maximilian N.; Heppe, Eva N.; Braun, Steve; Heverhagen, Johannes T.; Heldmaier, Gerhard

2014-01-01

We used noninvasive magnetic resonance imaging (MRI) and magnetic resonance spectroscopy to compare interscapular brown adipose tissue (iBAT) of wild-type (WT) and uncoupling protein 1 (UCP1)-knockout mice lacking UCP1-mediated nonshivering thermogenesis (NST). Mice were sequentially acclimated to an ambient temperature of 30°C, 18°C, and 5°C. We detected a remodeling of iBAT and a decrease in its lipid content in all mice during cold exposure. Ratios of energy-rich phosphates (ATP/ADP, phosphocreatine/ATP) in iBAT were maintained stable during noradrenergic stimulation of thermogenesis in cold- and warm-adapted mice and no difference between the genotypes was observed. As free fatty acids (FFAs) serve as fuel for thermogenesis and activate UCP1 for uncoupling of oxidative phosphorylation, brown adipose tissue is considered to be a main acceptor and consumer of FFAs. We measured a major loss of FFAs from iBAT during noradrenergic stimulation of thermogenesis. This mobilization of FFAs was observed in iBAT of WT mice as well as in mice lacking UCP1. The high turnover and the release of FFAs from iBAT suggests an enhancement of lipid metabolism, which in itself contributes to the sympathetically activated NST and which is independent from uncoupled respiration mediated by UCP1. Our study demonstrates that MRI, besides its potential for visualizing and quantification of fat tissue, is a valuable tool for monitoring functional in vivo processes like lipid and phosphate metabolism during NST. PMID:24343897

Traffic Lights in Trichodesmium. Regulation of Photosynthesis for Nitrogen Fixation Studied by Chlorophyll Fluorescence Kinetic Microscopy1

PubMed Central

Küpper, Hendrik; Ferimazova, Naila; Šetlík, Ivan; Berman-Frank, Ilana

2004-01-01

We investigated interactions between photosynthesis and nitrogen fixation in the non-heterocystous marine cyanobacterium Trichodesmium IMS101 at the single-cell level by two-dimensional (imaging) microscopic measurements of chlorophyll fluorescence kinetics. Nitrogen fixation was closely associated with the appearance of cells with high basic fluorescence yield (F0), termed bright cells. In cultures aerated with normal air, both nitrogen fixation and bright cells appeared in the middle of the light phase. In cultures aerated with 5% oxygen, both processes occurred at a low level throughout most of the day. Under 50% oxygen, nitrogen fixation commenced at the beginning of the light phase but declined soon afterwards. Rapid reversible switches between fluorescence levels were observed, which indicated that the elevated F0 of the bright cells originates from reversible uncoupling of the photosystem II (PSII) antenna from the PSII reaction center. Two physiologically distinct types of bright cells were observed. Type I had about double F0 compared to the normal F0 in the dark phase and a PSII activity, measured as variable fluorescence (Fv = Fm − F0), similar to normal non-diazotrophic cells. Correlation of type I cells with nitrogen fixation, oxygen concentration, and light suggests that this physiological state is connected to an up-regulation of the Mehler reaction, resulting in oxygen consumption despite functional PSII. Type II cells had more than three times the normal F0 and hardly any PSII activity measurable by variable fluorescence. They did not occur under low-oxygen concentrations, but appeared under high-oxygen levels outside the diazotrophic period, suggesting that this state represents a reaction to oxidative stress not necessarily connected to nitrogen fixation. In addition to the two high-fluorescence states, cells were observed to reversibly enter a low-fluorescence state. This occurred mainly after a cell went through its bright phase and may represent a fluorescence-quenching recovery phase. PMID:15299119

[Hair growth effect of minoxidil].

PubMed

Otomo, Susumu

2002-03-01

The length and size of hair are depend on the anagen term in its hair cycle. It has been reported that the some cell growth factors, such as VEGF, FGF-5S, IGF-1 and KGF, induce the proliferation of cells in the matrix, dermal papilla and dermal papillary vascular system and increase the amount of extra cellular matrix in dermal papilla and then maintain follicles in the anagen phase. On the other hand, negative factors, like FGF-5, thrombospondin, or still unknown ones, terminate the anagen phase. If the negative factors become dominant against cell proliferation factors according to fulfilling some time set by the biological clock for hair follicles, TGF beta induced in the matrix tissues evokes apoptosis of matrix cells and shifts the follicles from anagen to catagen. Androgenetic alopecia is caused by miniaturizing of hair follicles located in the frontal or crown part of scalp and are hereditarily more sensitive to androgen. In their hair cycles, the androgen shortens the anagen phase of follicles and shifts them to the catagen phase earlier than usual. The mode of action of hair growth effect of minoxidil is not completely elucidated, but the most plausible explanation proposed here is that minoxidil works as a sulfonylurea receptor (SUR) activator and prolongs the anagen phase of hair follicles in the following manner: minoxidil (1) induces cell growth factors such as VEGF, HGF, IGF-1 and potentiates HGF and IGF-1 actions by the activation of uncoupled SUR on the plasma membrane of dermal papilla cells, (2) inhibits of TGF beta induced apoptosis of hair matrix cells by opening the Kir 6.0 channel pore coupled with SUR on the mitochondrial inner membrane, and (3) dilates hair follicle arteries and increases blood flow in dermal papilla by opening the Kir 6.0 channel pore coupled with SUR on the plasma membrane of vascular smooth muscle cells.

[Analysis of brain hemometabolism behavior during carotid endarterectomy with temporary clamping.].

PubMed

Duval Neto, Gastão Fernandes; Niencheski, Augusto H

2004-04-01

Carotid endarterectomy with temporary clamping changes cerebral blood flow and cerebral metabolic oxygen demand ratio with consequent oligemic hypoxia or hemometabolic uncoupling. This study aimed at identifying changes in brain hemometabolism, evaluated through changes in oxyhemoglobin saturation in internal jugular vein bulb (SvjO2) during carotid endarterectomy with clamping, and at correlating these changes with potentially interfering factors, mainly end tidal CO2 pressure (P ET CO2) and cerebral perfusion pressure (CPP). Sixteen patients with unilateral carotid stenotic disease scheduled to carotid endarterectomy with carotid arterial clamping were enrolled in this study. Parameters including internal jugular bulb oxyhemoglobin saturation, stump pressure and end tidal CO2 pressure were measured at the following moments: M1 - pre-clamping; M2 - 3 minutes after clamping; M3 - pre-unclamping; M4 - post-unclamping). The comparison among SvjO2 (%, mean +/- SD) in all studied periods has shown differences between those recorded in moments M1 (52.25 +/- 7.87) and M2 (47.43 +/- 9.19). This initial decrease stabilized during temporary clamping, showing decrease in the comparison between M2 and M3 (46.56 +/- 9.25), without statistical significance (p = ns). At post-unclamping, M4 (47.68 +/- 9.12), SvjO2 was increased as compared to M2 and M3 clamping stages, however it was still lower than that of pre-clamping stage M1.(M4 x M1 - p < 0.04) This SvjO2 decrease was followed by significant cerebral perfusion pressure (stump pressure) decrease. Factors influencing this brain hemometabolic uncoupling trend were correlated to P ET CO2. The comparison between CPP and SvjO2 showed weak correlation devoid of statistical significance. In the conditions of our study, SvjO2 measurement is a fast and effective way of clinically monitoring changes in CBF/CMRO2 ratio. Temporary carotid clamping implies in a trend towards brain hemometabolic uncoupling and, as a consequence, to oligemic ischemia; cerebral perfusion pressure does not assesses brain hemometabolic status (CBF and CMRO2 ratio); hypocapnia, may lead to brain hemometabolic uncoupling; P ET CO2 monitoring is an innocuous and efficient way to indirectly monitor PaCO2 preventing inadvertent hypocapnia and its deleterious effects on CBF/CMRO2 ratio during temporary carotid clamping.

Marked over expression of uncoupling protein-2 in beta cells exerts minor effects on mitochondrial metabolism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hals, Ingrid K., E-mail: ingrid.hals@ntnu.no; Ogata, Hirotaka; Pettersen, Elin

2012-06-29

Highlights: Black-Right-Pointing-Pointer The impact of UCP-2 over expression on mitochondrial function is controversial. Black-Right-Pointing-Pointer We tested mitochondrial functions at defined levels of overexpression. Black-Right-Pointing-Pointer We find minor increases of fatty acid oxidation and uncoupling. Black-Right-Pointing-Pointer Effects were seen only at high level (fourfold) of over expression. Black-Right-Pointing-Pointer Hence it is doubtful whether these effects are of importance in diabetes. -- Abstract: Evidence is conflicting as to the impact of elevated levels of uncoupling protein-2 (UCP-2) on insulin-producing beta cells. Here we investigated effects of a fourfold induction of UCP-2 protein primarily on mitochondrial parameters and tested for replication of positivemore » findings at a lower level of induction. We transfected INS-1 cells to obtain a tet-on inducible cell line. A 48 h exposure to 1 {mu}g/ml of doxycycline (dox) induced UCP-2 fourfold (424 {+-} 113%, mean {+-} SEM) and 0.1 {mu}g/ml twofold (178 {+-} 29%, n = 3). Fourfold induced cells displayed normal viability (MTT, apoptosis), normal cellular insulin contents and, glucose-induced insulin secretion (+27 {+-} 11%) as well as D-[U-{sup 14}C]-glucose oxidation (+5 {+-} 9% at 11 mM glucose). Oxidation of [1-{sup 14}C]-oleate was increased from 4088 to 5797 fmol/{mu}g prot/2 h at 3.3 mM glucose, p < 0.03. Oxidation of L-[{sup 14}C(U)]-glutamine was unaffected. Induction of UCP-2 did not significantly affect measures of mitochondrial membrane potential (Rhodamine 123) or mitochondrial mass (Mitotracker Green) and did not affect ATP levels. Oligomycin-inhibited oxygen consumption (a measure of mitochondrial uncoupling) was marginally increased, the effect being significant in comparison with dox-only treated cells, p < 0.05. Oxygen radicals, assessed by dichlorofluorescin diacetate, were decreased by 30%, p < 0.025. Testing for the lower level of UCP-2 induction did not reproduce any of the positive findings. A fourfold induction of UCP-2 was required to exert minor metabolic effects. These findings question an impact of moderately elevated UCP-2 levels in beta cells as seen in diabetes.« less

Sulfide-inhibition of mitochondrial respiration at very low oxygen concentrations.

PubMed

Matallo, J; Vogt, J; McCook, O; Wachter, U; Tillmans, F; Groeger, M; Szabo, C; Georgieff, M; Radermacher, P; Calzia, E

2014-09-15

Our aim was to study the ability of an immortalized cell line (AMJ2-C11) to sustain aerobic cell respiration at decreasing oxygen concentrations under continuous sulfide exposure. We assumed that the rate of elimination of sulfide through the pathway linked to the mitochondrial respiratory chain and therefore operating under aerobic conditions, should decrease with limiting oxygen concentrations. Thus, sulfide's inhibition of cellular respiration would occur faster under continuous sulfide exposure when the oxygen concentration is in the very low range. The experiments were performed with an O2K-oxygraph (Oroboros Instruments) by suspending 0.5-1×10(6) cells in 2 ml of continuously stirred respiration medium at 37 °C and calculating the oxygen flux (JO2) as the negative derivative of the oxygen concentration in the medium. The cells were studied in two different metabolic states, namely under normal physiologic respiration (1) and after uncoupling of mitochondrial respiration (2). Oxygen concentration was controlled by means of a titration-injection pump, resulting in average concentration values of 0.73±0.05 μM, 3.1±0.2 μM, and 6.2±0.2 μM. Simultaneously we injected a 2 mM Na2S solution at a continuous rate of 10 μl/s in order to quantify the titration-time required to reduce the JO2 to 50% of the initial respiratory activity. Under the lowest oxygen concentration this effect was achieved after 3.5 [0.3;3.5] and 11.7 [6.2;21.2]min in the uncoupled and coupled state, respectively. This time was statistically significantly shorter when compared to the intermediate and the highest O2 concentrations tested, which yielded values of 24.6 [15.5;28.1]min (coupled) and 35.9 [27.4;59.2]min (uncoupled), as well as 42.4 [27.5;42.4]min (coupled) and 51.5 [46.4;51.7]min (uncoupled). All data are medians [25%, and 75% percentiles]. Our results confirm that the onset of inhibition of cell respiration by sulfide occurs earlier under a continuous exposure when approaching the anoxic condition. This property may contribute to the physiological role of sulfide as an oxygen sensor. Copyright © 2014 Elsevier Inc. All rights reserved.

Sulfide-Inhibition of Mitochondrial Respiration at Very Low Oxygen Concentrations

PubMed Central

Matallo, J; Vogt, J; McCook, O; Wachter, U; Tillmans, F; Groeger, M; Szabo, C; Georgieff, M; Radermacher, P; Calzia, E

2014-01-01

Our aim was to study the capacity of an immortalized cell line (AMJ2-C11) to sustain aerobic cell respiration at decreasing oxygen concentrations under continuous sulfide exposure. We assumed that the capacity of the pathway metabolizing and eliminating sulfide, which is linked to the mitochondrial respiratory chain and therefore operates under aerobic conditions, should decrease with limiting oxygen concentrations. Thus, sulfide’s inhibition of cellular respiration would be dependent of the oxygen concentration in the very low range. The experiments were performed with an O2K-oxygraph (Oroboros Instruments) by suspending 0.5 – 1 × 106 cells in 2 ml of continuously stirred respiration medium at 37°C and calculating the oxygen flux (JO2) as the negative derivative of the oxygen concentration in the medium. The cells were studied in two different metabolic states, namely under normal physiologic respiration (1) and after uncoupling of mitochondrial respiration (2). Oxygen concentration was controlled by means of a titration-injection pump, resulting in average concentration values of 0.73 ± 0.05 μM, 3.1 ± 0.2 μM, and 6.2 ± 0.2 μM. Simultaneously we injected a 2 mM Na2S solution at a continuous rate of 10 μl/s in order to quantify the titration-time required to reduce the JO2 to 50% of the initial respiratory activity. Under the lowest oxygen concentration this effect was achieved after 3.5 [0.3; 3.5] and 11.7 [6.2;21.2] min in the uncoupled and coupled state, respectively. This time was statistically significantly shorter when compared to the intermediate and the highest O2 concentrations tested, which yielded values of 24.6[15.5;28.1] min (coupled) and 35.9[27.4;59.2] min (uncoupled), as well as 42.4 [27.5;42.4] min (coupled) and 51.5 [46.4;51.7] min (uncoupled). All data are medians [25%, and 75% percentiles]. Our results suggest that elimination of sulfide in these cells is limited by oxygen availability when approaching the anoxic condition. This property may contribute to the physiological role of sulfide as an oxygen sensor. PMID:24963794

Uncoupled vs. coupled thrust belt-foreland deformation: a model for northern Patagonia inferred from U-Th/He and apatite fission track dating

NASA Astrophysics Data System (ADS)

Savignano, Elisa; Mazzoli, Stefano; Zattin, Massimiliano; Gautheron, Cécile; Franchini, Marta

2017-04-01

The study of the Cretaceous - Cenozoic evolution of the Patagonian Andes represents a great opportunity to investigate the effects of coupling between deep lithospheric processes and near-surface deformation. Low-temperature thermochronological systems are ideally suited for detecting events involving rocks in the uppermost part of the crust because they record time and rates of cooling related to exhumation of the top few kilometers of the crust. The Patagonia region, although characterized by a general continuity of the Andean orogen along its strike, shows an appreciable internal tectonic segmentation (marked by a variable position of the magmatic arc and of the deformation front in the retroarc area) at various latitudes. This complex structural architecture has been interpreted as the result of different processes acting since the Late Cretaceous. The present-day configuration of the southern Andes is interpreted to have been controlled by alternating stages of flat- and steep-slab subduction, which produced shortening and upper plate extension episodes,, respectively. Furthermore, the deformation in this whole retroarc sector varied not only in time (i.e. with major 'cycles' of mountain building and orogenic collapse), but also in space, due to the variable transmission of horizontal compressive stress away from the orogen, that produced an irregular unroofing pattern. In this study, we have integrated field structural observations with new apatite (U-Th)/He data (AHe) and apatite fission-track (AFT) ages in the north Patagonia region (at latitudes between 40° and 44°S) in order to analyse and compare the exhumation patterns from the frontal part of the orogen and from the adjacent foreland sector, as well as to gain new insights into the timing and modes of coupling vs. uncoupling of the deformation between the northern Patagonian fold and thrust belt and its foreland. The obtained data indicate a markedly different unroofing pattern between the 'broken foreland' area (characterized by Late Cretaceous to Paleogene exhumation) and the adjacent Andean sector to the west, which is dominated by Miocene-Pliocene exhumation. Our study supports the idea that the configuration of the slab (flat vs. steep) during subduction controls the coupling vs. uncoupling of the deformation between the thrust belt and the foreland. Along the studied transect, late Miocene to Pliocene AHe ages from the frontal part of the northern Patagonian Andes correlate well with a rapid recent shortening and exhumation stage that took place in the thrust belt during steep-slab subduction and rollback. On the other hand, AHe ages obtained for the 'broken foreland' unravelled exhumation at near-surface conditions during Late Cretaceous to Paleogene times, when a prolonged phase of flat-slab subduction favoured the coupling between the thrust belt and the foreland area and associated widespread shortening able to reactivate inherited rift-related structures.

MIA analysis of FPGA BPMs and beam optics at APS

NASA Astrophysics Data System (ADS)

Ji, Da-Heng; Wang, Chun-Xi; Qin, Qing

2012-11-01

Model independent analysis, which was developed for high precision and fast beam dynamics analysis, is a promising diagnostic tool for modern accelerators. We implemented a series of methods to analyze the turn-by-turn BPM data. Green's functions corresponding to the local transfer matrix elements R12 or R34 are extracted from BPM data and fitted with the model lattice using least-square fitting. Here, we report experimental results obtained from analyzing the transverse motion of a beam in the storage ring at the Advanced Photon Source. BPM gains and uncoupled optics parameters are successfully determined. Quadrupole strengths are adjusted for fitting but can not be uniquely determined in general due to an insufficient number of BPMs.

The Kept-On Workforce.

ERIC Educational Resources Information Center

Kaye, Beverly L.

1998-01-01

In the aftermath of downsizing, managers must deal with the attitudes of the surviving employees. Some will offer an example of a bright future and are valuable contributors to employee morale. Others may experience sadness, anger, mistrust, and a psychological uncoupling from the organization. (JOW)

Exploratory study of partial isolation of highway bridges.

DOT National Transportation Integrated Search

2011-01-01

A special class of seismically isolated bridges shares a common feature in that both ends of the superstructure are restrained and isolators over the columns of bridge uncouple the superstructure from the ground motions. They are defined as partial i...

Examining a role for PKG Iα oxidation in the pathogenesis of cardiovascular dysfunction during diet-induced obesity.

PubMed

Rudyk, Olena; Eaton, Philip

2017-09-01

Protein kinase G (PKG) Iα is the end-effector kinase that mediates nitric oxide (NO)-dependent and oxidant-dependent vasorelaxation to maintain blood pressure during health. A hallmark of cardiovascular disease is attenuated NO production, which in part is caused by NO Synthase (NOS) uncoupling, which in turn increases oxidative stress because of superoxide generation. NOS uncoupling promotes PKG Iα oxidation to the interprotein disulfide state, likely mediated by superoxide-derived hydrogen peroxide, and because the NO-cyclic guanosine monophosphate (cGMP) pathway otherwise negatively regulates oxidation of the kinase to its active disulfide dimeric state. Diet-induced obesity is associated with NOS uncoupling, which may in part contribute to the associated cardiovascular dysfunction due to exacerbated PKG Iα disulfide oxidation to the disulfide state. This is a rational hypothesis because PKG Iα oxidation is known to significantly contribute to heart failure that arises from chronic myocardial oxidative stress. Bovine arterial endothelial cells (BAECs) or smooth muscle cells (SMCs) were exposed to drugs that uncouple NOS. These included 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) which promotes its S-glutathiolation, 4-diamino-6-hydroxy-pyrimidine (DAHP) which inhibits guanosine-5'-triphosphate-cyclohydrolase 2 to prevent BH 4 synthesis or methotrexate (MTX) which inhibits the regeneration of BH 4 from BH 2 by dihydrofolate reductase. While all the drugs mentioned above induced robust PKG Iα disulfide dimerization in cells, exposure of BAECs to NOS inhibitor L-NMMA did not. Increased PKG Iα disulfide formation occurred in hearts and aortae from mice treated in vivo with DAHP (10mM in a drinking water for 3 weeks). Redox-dead C42S PKG Iα knock-in (KI) mice developed less pronounced cardiac posterior wall hypertrophy and did not develop cardiac dysfunction, assessed by echocardiography, compared to the wild-type (WT) mice after chronic DAHP treatment. WT or KI mice were then subjected to a diet-induced obesity protocol by feeding them with a high fat Western-type diet (RM 60% AFE) for 27 weeks, which increased body mass, adiposity, plasma leptin, resistin and glucagon levels comparably in each genotype. Obesity-induced hypertension, assessed by radiotelemetry, was mild and transient in the WT, while the basally hypertensive KI mice were resistant to further increases in blood pressure following high fat feeding. Although the obesogenic diet caused mild cardiac dysfunction in the WT but not the KI mice, gross changes in myocardial structure monitored by echocardiography were not apparent in either genotype. The level of cyclic guanosine monophosphate (cGMP) was decreased in the aortae of WT and KI mice following high fat feeding. PKG Iα oxidation was not evident in the hearts of WT mice fed a high fat diet. Despite robust evidence for PKG Iα oxidation during NOS uncoupling in cell models, it is unlikely that PKG Iα oxidation occurs to a significant extent in vivo during diet-induced obesity and so is unlikely to mediate the associated cardiovascular dysfunction. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

AKI after conditional and kidney-specific knockdown of Stanniocalcin-1

USDA-ARS?s Scientific Manuscript database

Stanniocalcin-1 is an intracrine protein; it binds to the cell surface, is internalized to the mitochondria, and diminishes superoxide generation through induction of uncoupling proteins. In vitro, stanniocalcin-1 inhibits macrophages and preserves endothelial barrier function, and transgenic overex...

An Investigation of Bank-to-Turn Missiles.

DTIC Science & Technology

1986-06-01

Aerodynamic Model and Analysis The aerodynamic transfer functions of the uncoupled yaw channel autopilot are according to Karadimas , C. thesis [Ref. 41: a...Thesis, Naval Postgraduate School, Monterey California, December 1985 3. Ogata, K., Modern Control Engineering, Prentice-Hall Inc., 1970. 4. Karadimas

Improved Force-And-Torque Sensor Assembly

NASA Technical Reports Server (NTRS)

Bamford, Robert M.

1991-01-01

Improved sensor assembly measures forces and torques of interaction between supporting and supported object. Measures all three components of force and all three components of torque. Force measurements uncoupled from torque measurements. Price for improved measurement capability, complexity and flexibility, excessive in some applications.

A novel approach to dual excitation ratiometric optical mapping of cardiac action potentials with di-4-ANEPPS using pulsed LED excitation.

PubMed

Bachtel, Andrew D; Gray, Richard A; Stohlman, Jayna M; Bourgeois, Elliot B; Pollard, Andrew E; Rogers, Jack M

2011-07-01

We developed a new method for ratiometric optical mapping of transmembrane potential (V(m)) in cardiac preparations stained with di-4-ANEPPS. V(m)-dependent shifts of excitation and emission spectra establish two excitation bands (<481 and >481 nm) that produce fluorescence changes of opposite polarity within a single emission band (575-620 nm). The ratio of these positive and negative fluorescence signals (excitation ratiometry) increases V(m) sensitivity and removes artifacts common to both signals. We pulsed blue (450 ± 10 nm) and cyan (505 ± 15 nm) light emitting diodes (LEDs) at 375 Hz in alternating phase synchronized to a camera (750 frames-per-second). Fluorescence was bandpass filtered (585 ± 20 nm). This produced signals with upright (blue) and inverted (cyan) action potentials (APs) interleaved in sequential frames. In four whole swine hearts with motion chemically arrested, fractional fluorescence for blue, cyan, and ratio signals was 1.2 ± 0.3%, 1.2 ± 0.3%, and 2.4 ± 0.6%, respectively. Signal-to-noise ratios were 4.3 ± 1.4, 4.0 ± 1.2, and 5.8 ± 1.9, respectively. After washing out the electromechanical uncoupling agent, we characterized motion artifact by cross-correlating blue, cyan, and ratio signals with a signal with normal AP morphology. Ratiometry improved cross-correlation coefficients from 0.50 ± 0.48 to 0.81 ± 0.25, but did not cancel all motion artifacts. These findings demonstrate the feasibility of pulsed LED excitation ratiometry in myocardium. © 2011 IEEE

A Novel Approach to Dual Excitation Ratiometric Optical Mapping of Cardiac Action Potentials with Di-4-ANEPPS using Pulsed LED Excitation

PubMed Central

Bachtel, Andrew D.; Gray, Richard A.; Stohlman, Jayna M.; Bourgeois, Elliot B.; Pollard, Andrew E.

2011-01-01

We developed a new method for ratiometric optical mapping of transmembrane potential (Vm) in cardiac preparations stained with di-4-ANEPPS. Vm-dependent shifts of excitation and emission spectra establish two excitation bands (<481 and >481 nm) that produce fluorescence changes of opposite polarity within a single emission band (575–620 nm). The ratio of these positive and negative fluorescence signals (excitation ratiometry) increases Vm sensitivity and removes artifacts common to both signals. We pulsed blue (450±10 nm) and cyan (505±15 nm) light emitting diodes (LEDs) at 375 Hz in alternating phase synchronized to a camera (750 frames-per-second). Fluorescence was bandpass filtered (585±20 nm). This produced signals with upright (blue) and inverted (cyan) action potentials (APs) interleaved in sequential frames. In 4 whole swine hearts with motion chemically arrested, fractional fluorescence for blue, cyan, and ratio signals was 1.2±0.3%, 1.2±0.3%, and 2.4±0.6%, respectively. Signal-to-noise ratios were 4.3±1.4, 4.0±1.2, and 5.8±1.9, respectively. After washing out the electromechanical uncoupling agent, we characterized motion artifact by cross-correlating blue, cyan, and ratio signals with a signal with normal AP morphology. Ratiometry improved cross-correlation coefficients from 0.50±0.48 to 0.81±0.25, but did not cancel all motion artifacts. These findings demonstrate the feasibility of pulsed LED excitation ratiometry in myocardium. PMID:21536528

Tree-Ring Stable Isotopes Reveal Twentieth-Century Increases in Water-Use Efficiency of Fagus sylvatica and Nothofagus spp. in Italian and Chilean Mountains

PubMed Central

Tognetti, Roberto; Lombardi, Fabio; Lasserre, Bruno; Cherubini, Paolo; Marchetti, Marco

2014-01-01

Changes in intrinsic water use efficiency (iWUE) were investigated in Fagus sylvatica and Nothofagus spp. over the last century. We combined dendrochronological methods with dual-isotope analysis to investigate whether atmospheric changes enhanced iWUE of Fagus and Nothofagus and tree growth (basal area increment, BAI) along latitudinal gradients in Italy and Chile. Post-maturation phases of the trees presented different patterns in δ13C, Δ13C, δ18O, Ci (internal CO2 concentration), iWUE, and BAI. A continuous enhancement in isotope-derived iWUE was observed throughout the twentieth century, which was common to all sites and related to changes in Ca (ambient CO2 concentration) and secondarily to increases in temperature. In contrast to other studies, we observed a general increasing trend of BAI, with the exception of F. sylvatica in Aspromonte. Both iWUE and BAI were uncoupled with the estimated drought index, which is in agreement with the absence of enduring decline in tree growth. In general, δ13C and δ18O showed a weak relationship, suggesting the major influence of photosynthetic rate on Ci and δ13C, and the minor contribution of the regulation of stomatal conductance to iWUE. The substantial warming observed during the twentieth century did not result in a clear pattern of increased drought stress along these latitudinal transects, because of the variability in temporal trends of precipitation and in specific responses of populations. PMID:25398040

Causes of the large warm bias in the Angola-Benguela Frontal Zone in the Norwegian Earth System Model

NASA Astrophysics Data System (ADS)

Koseki, Shunya; Keenlyside, Noel; Demissie, Teferi; Toniazzo, Thomas; Counillon, Francois; Bethke, Ingo; Ilicak, Mehmet; Shen, Mao-Lin

2018-06-01

We have investigated the causes of the sea surface temperature (SST) bias in the Angola-Benguela Frontal Zone (ABFZ) of the southeastern Atlantic Ocean simulated by the Norwegian Earth System Model (NorESM). Similar to other coupled-models, NorESM has a warm SST bias in the ABFZ of up to 8 °C in the annual mean. Our analysis of NorESM reveals that a cyclonic surface wind bias over the ABFZ drives a locally excessively strong southward (0.05 m/s (relative to observation)) Angola Current displacing the ABFZ southward. A series of uncoupled stand-alone atmosphere and ocean model simulations are performed to investigate the cause of the coupled model bias. The stand-alone atmosphere model driven with observed SST exhibits a similar cyclonic surface circulation bias; while the stand-alone ocean model forced with the reanalysis data produces a warm SST in the ABFZ with a magnitude approximately half of that in the coupled NorESM simulation. An additional uncoupled sensitivity experiment shows that the atmospheric model's local negative surface wind curl generates anomalously strong Angola Current at the ocean surface. Consequently, this contributes to the warm SST bias in the ABFZ by 2 °C (compared to the reanalysis forced simulation). There is no evidence that local air-sea feedbacks among wind stress curl, SST, and sea level pressure (SLP) affect the ABFZ SST bias. Turbulent surface heat flux differences between coupled and uncoupled experiments explain the remaining 2 °C warm SST bias in NorESM. Ocean circulation, upwelling and turbulent heat flux errors all modulate the intensity and the seasonality of the ABFZ errors.

Therapeutic effect of enhancing endothelial nitric oxide synthase (eNOS) expression and preventing eNOS uncoupling

PubMed Central

Förstermann, Ulrich; Li, Huige

2011-01-01

Nitric oxide (NO) produced by the endothelium is an important protective molecule in the vasculature. It is generated by the enzyme endothelial NO synthase (eNOS). Similar to all NOS isoforms, functional eNOS transfers electrons from nicotinamide adenine dinucleotide phosphate (NADPH), via the flavins flavin adenine dinucleotide and flavin mononucleotide in the carboxy-terminal reductase domain, to the heme in the amino-terminal oxygenase domain. Here, the substrate L-arginine is oxidized to L-citrulline and NO. Cardiovascular risk factors such as diabetes mellitus, hypertension, hypercholesterolaemia or cigarette smoking reduce bioactive NO. These risk factors lead to an enhanced production of reactive oxygen species (ROS) in the vessel wall. NADPH oxidases represent major sources of this ROS and have been found upregulated in the presence of cardiovascular risk factors. NADPH-oxidase-derived superoxide avidly reacts with eNOS-derived NO to form peroxynitrite (ONOO-). The essential NOS cofactor (6R-)5,6,7,8-tetrahydrobiopterin (BH4) is highly sensitive to oxidation by this ONOO-. In BH4 deficiency, oxygen reduction uncouples from NO synthesis, thereby converting NOS to a superoxide-producing enzyme. Among conventional drugs, compounds interfering with the renin-angiotensin-aldosterone system and statins can reduce vascular oxidative stress and increase bioactive NO. In recent years, we have identified a number of small molecules that have the potential to prevent eNOS uncoupling and, at the same time, enhance eNOS expression. These include the protein kinase C inhibitor midostaurin, the pentacyclic triterpenoids ursolic acid and betulinic acid, the eNOS enhancing compounds AVE9488 and AVE3085, and the polyphenolic phytoalexin trans-resveratrol. Such compounds enhance NO production from eNOS also under pathophysiological conditions and may thus have therapeutic potential. PMID:21198553

Human neuronal uncoupling proteins 4 and 5 (UCP4 and UCP5): structural properties, regulation, and physiological role in protection against oxidative stress and mitochondrial dysfunction.

PubMed

Ramsden, David B; Ho, Philip W-L; Ho, Jessica W-M; Liu, Hui-Fang; So, Danny H-F; Tse, Ho-Man; Chan, Koon-Ho; Ho, Shu-Leong

2012-07-01

Uncoupling proteins (UCPs) belong to a large family of mitochondrial solute carriers 25 (SLC25s) localized at the inner mitochondrial membrane. UCPs transport protons directly from the intermembrane space to the matrix. Of five structural homologues (UCP1 to 5), UCP4 and 5 are principally expressed in the central nervous system (CNS). Neurons derived their energy in the form of ATP that is generated through oxidative phosphorylation carried out by five multiprotein complexes (Complexes I-V) embedded in the inner mitochondrial membrane. In oxidative phosphorylation, the flow of electrons generated by the oxidation of substrates through the electron transport chain to molecular oxygen at Complex IV leads to the transport of protons from the matrix to the intermembrane space by Complex I, III, and IV. This movement of protons to the intermembrane space generates a proton gradient (mitochondrial membrane potential; MMP) across the inner membrane. Complex V (ATP synthase) uses this MMP to drive the conversion of ADP to ATP. Some electrons escape to oxygen-forming harmful reactive oxygen species (ROS). Proton leakage back to the matrix which bypasses Complex V resulting in a major reduction in ROS formation while having a minimal effect on MMP and hence, ATP synthesis; a process termed "mild uncoupling." UCPs act to promote this proton leakage as means to prevent excessive build up of MMP and ROS formation. In this review, we discuss the structure and function of mitochondrial UCPs 4 and 5 and factors influencing their expression. Hypotheses concerning the evolution of the two proteins are examined. The protective mechanisms of the two proteins against neurotoxins and their possible role in regulating intracellular calcium movement, particularly with regard to the pathogenesis of Parkinson's disease are discussed.

Small structural changes on a hydroquinone scaffold determine the complex I inhibition or uncoupling of tumoral oxidative phosphorylation.

PubMed

Urra, Félix A; Córdova-Delgado, Miguel; Lapier, Michel; Orellana-Manzano, Andrea; Acevedo-Arévalo, Luis; Pessoa-Mahana, Hernán; González-Vivanco, Jaime M; Martínez-Cifuentes, Maximiliano; Ramírez-Rodríguez, Oney; Millas-Vargas, Juan Pablo; Weiss-López, Boris; Pavani, Mario; Ferreira, Jorge; Araya-Maturana, Ramiro

2016-01-15

Mitochondria participate in several distinctiveness of cancer cell, being a promising target for the design of anti-cancer compounds. Previously, we described that ortho-carbonyl hydroquinone scaffold 14 inhibits the complex I-dependent respiration with selective anti-proliferative effect on mouse mammary adenocarcinoma TA3/Ha cancer cells; however, the structural requirements of this hydroquinone scaffold to affect the oxidative phosphorylation (OXPHOS) of cancer cells have not been studied in detail. Here, we characterize the mitochondrial metabolism of TA3/Ha cancer cells, which exhibit a high oxidative metabolism, and evaluate the effect of small structural changes of the hydroquinone scaffold 14 on the respiration of this cell line. Our results indicate that these structural changes modify the effect on OXPHOS, obtaining compounds with three alternative actions: inhibitors of complex I-dependent respiration, uncoupler of OXPHOS and compounds with both actions. To confirm this, the effect of a bicyclic hydroquinone (9) was evaluated in isolated mitochondria. Hydroquinone 9 increased mitochondrial respiration in state 4o without effects on the ADP-stimulated respiration (state 3ADP), decreasing the complexes I and II-dependent respiratory control ratio. The effect on mitochondrial respiration was reversed by 6-ketocholestanol addition, indicating that this hydroquinone is a protonophoric uncoupling agent. In intact TA3/Ha cells, hydroquinone 9 caused mitochondrial depolarization, decreasing intracellular ATP and NAD(P)H levels and GSH/GSSG ratio, and slightly increasing the ROS levels. Moreover, it exhibited selective NAD(P)H availability-dependent anti-proliferative effect on cancer cells. Therefore, our results indicate that the ortho-carbonyl hydroquinone scaffold offers the possibility to design compounds with specific actions on OXPHOS of cancer cells.

Control of mitochondrial pH by uncoupling protein 4 in astrocytes promotes neuronal survival.

PubMed

Perreten Lambert, Hélène; Zenger, Manuel; Azarias, Guillaume; Chatton, Jean-Yves; Magistretti, Pierre J; Lengacher, Sylvain

2014-11-07

Brain activity is energetically costly and requires a steady and highly regulated flow of energy equivalents between neural cells. It is believed that a substantial share of cerebral glucose, the major source of energy of the brain, will preferentially be metabolized in astrocytes via aerobic glycolysis. The aim of this study was to evaluate whether uncoupling proteins (UCPs), located in the inner membrane of mitochondria, play a role in setting up the metabolic response pattern of astrocytes. UCPs are believed to mediate the transmembrane transfer of protons, resulting in the uncoupling of oxidative phosphorylation from ATP production. UCPs are therefore potentially important regulators of energy fluxes. The main UCP isoforms expressed in the brain are UCP2, UCP4, and UCP5. We examined in particular the role of UCP4 in neuron-astrocyte metabolic coupling and measured a range of functional metabolic parameters including mitochondrial electrical potential and pH, reactive oxygen species production, NAD/NADH ratio, ATP/ADP ratio, CO2 and lactate production, and oxygen consumption rate. In brief, we found that UCP4 regulates the intramitochondrial pH of astrocytes, which acidifies as a consequence of glutamate uptake, with the main consequence of reducing efficiency of mitochondrial ATP production. The diminished ATP production is effectively compensated by enhancement of glycolysis. This nonoxidative production of energy is not associated with deleterious H2O2 production. We show that astrocytes expressing more UCP4 produced more lactate, which is used as an energy source by neurons, and had the ability to enhance neuronal survival. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Dodecyl and octyl esters of fluorescein as protonophores and uncouplers of oxidative phosphorylation in mitochondria at submicromolar concentrations.

PubMed

Shchepinova, Maria M; Denisov, Stepan S; Kotova, Elena A; Khailova, Ljudmila S; Knorre, Dmitry A; Korshunova, Galina A; Tashlitsky, Vadim N; Severin, Fedor F; Antonenko, Yuri N

2014-01-01

In our search for fluorescent uncouplers of oxidative phosphorylation, three esters of fluorescein, n-butyl-, n-octyl-, and n-dodecyl-oxycarbonyl-fluorescein (C4-FL, C8-FL, C12-FL) were synthesized and characterized. With increasing liposomal lipid content, the long-chain alkyl derivatives of fluorescein (C8-FL, C12-FL and commercially available C18-FL), but not C4-FL and unsubstituted fluorescein, exhibited an increase in fluorescence polarization reflecting the dye binding to liposomes. C12-FL induced proton permeability in lipid membranes, while C4-FL was inactive. In contrast to C4-FL and C18-FL, C12-FL and C8-FL increased the respiration rate and decreased the membrane potential of isolated rat liver mitochondria with half-maximal effective concentrations of 700nM and 300nM, respectively. The effect of Cn-FL on the respiration correlated with that on proton permeability of the inner mitochondrial membrane, as measured by induction of mitochondria swelling in the potassium acetate medium. Binding of C8-FL to mitochondria depended on their energization, which was apparently associated with pH gradient generation across the inner mitochondrial membrane in the presence of a respiratory substrate. In wild-type yeast cells, C12-FL localized predominantly in plasma membrane, whereas in AD1-8 mutants lacking MDR pumps, it stained cytoplasmic organelles with some preference for mitochondria. Fluorescent uncouplers can be useful as a tool for determining their localization in a cell or distribution between different tissues in a living animal by fluorescent microscopy. © 2013.

Transcriptional upregulation of mitochondrial uncoupling protein 2 protects against oxidative stress-associated neurogenic hypertension.

PubMed

Chan, Samuel H H; Wu, Chiung-Ai; Wu, Kay L H; Ho, Ying-Hao; Chang, Alice Y W; Chan, Julie Y H

2009-10-23

Mitochondrial uncoupling proteins (UCPs) belong to a superfamily of mitochondrial anion transporters that uncouple ATP synthesis from oxidative phosphorylation and mitigates mitochondrial reactive oxygen species production. We assessed the hypothesis that UCP2 participates in central cardiovascular regulation by maintaining reactive oxygen species homeostasis in the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons that maintain vasomotor tone located. We also elucidated the molecular mechanisms that underlie transcriptional upregulation of UCP2 in response to oxidative stress in RVLM. In Sprague-Dawley rats, transcriptional upregulation of UCP2 in RVLM by rosiglitazone, an activator of its transcription factor peroxisome proliferator-activated receptor (PPAR)gamma, reduced mitochondrial hydrogen peroxide level in RVLM and systemic arterial pressure. Oxidative stress induced by microinjection of angiotensin II into RVLM augmented UCP2 mRNA or protein expression in RVLM, which was antagonized by comicroinjection of NADPH oxidase inhibitor (diphenyleneiodonium chloride), superoxide dismutase mimetic (tempol), or p38 mitogen-activated protein kinase inhibitor (SB203580) but not by extracellular signal-regulated kinase 1/2 inhibitor (U0126). Angiotensin II also induced phosphorylation of the PPARgamma coactivator, PPARgamma coactivator (PGC)-1alpha, and an increase in formation of PGC-1alpha/PPARgamma complexes in a p38 mitogen-activated protein kinase-dependent manner. Intracerebroventricular infusion of angiotensin II promoted an increase in mitochondrial hydrogen peroxide production in RVLM and chronic pressor response, which was potentiated by gene knockdown of UCP2 but blunted by rosiglitazone. These results suggest that transcriptional upregulation of mitochondrial UCP2 in response to an elevation in superoxide plays an active role in feedback regulation of reactive oxygen species production in RVLM and neurogenic hypertension associated with chronic oxidative stress.

Arginine de novo and nitric oxide production in disease states

PubMed Central

Luiking, Yvette C.; Ten Have, Gabriella A. M.; Wolfe, Robert R.

2012-01-01

Arginine is derived from dietary protein intake, body protein breakdown, or endogenous de novo arginine production. The latter may be linked to the availability of citrulline, which is the immediate precursor of arginine and limiting factor for de novo arginine production. Arginine metabolism is highly compartmentalized due to the expression of the enzymes involved in arginine metabolism in various organs. A small fraction of arginine enters the NO synthase (NOS) pathway. Tetrahydrobiopterin (BH4) is an essential and rate-limiting cofactor for the production of NO. Depletion of BH4 in oxidative-stressed endothelial cells can result in so-called NOS3 “uncoupling,” resulting in production of superoxide instead of NO. Moreover, distribution of arginine between intracellular transporters and arginine-converting enzymes, as well as between the arginine-converting and arginine-synthesizing enzymes, determines the metabolic fate of arginine. Alternatively, NO can be derived from conversion of nitrite. Reduced arginine availability stemming from reduced de novo production and elevated arginase activity have been reported in various conditions of acute and chronic stress, which are often characterized by increased NOS2 and reduced NOS3 activity. Cardiovascular and pulmonary disorders such as atherosclerosis, diabetes, hypercholesterolemia, ischemic heart disease, and hypertension are characterized by NOS3 uncoupling. Therapeutic applications to influence (de novo) arginine and NO metabolism aim at increasing substrate availability or at influencing the metabolic fate of specific pathways related to NO bioavailability and prevention of NOS3 uncoupling. These include supplementation of arginine or citrulline, provision of NO donors including inhaled NO and nitrite (sources), NOS3 modulating agents, or the targeting of endogenous NOS inhibitors like asymmetric dimethylarginine. PMID:23011059

Effect of phytotoxic secondary metabolites and semisynthetic compounds from endophytic fungus Xylaria feejeensis strain SM3e-1b on spinach chloroplast photosynthesis.

PubMed

Macías-Rubalcava, Martha Lydia; García-Méndez, Marbella Claudia; King-Díaz, Beatriz; Macías-Ruvalcaba, Norma Angélica

2017-01-01

We investigated the mechanism of action on the photosynthesis light reactions of three major secondary metabolites produced by the endophytic fungus Xylaria feejeensis strain SM3e-1b, isolated from Sapium macrocarpum; and four novel derivatives of coriloxine, a major compound produced by X. feejeensis. The natural phytotoxins include one epoxycyclohexenone derivative, coriloxine (1), and two quinone derivatives (2-3). The semisynthetic derivatives of coriloxine are two cyclohexenone (4-6) and two quinone compounds (5-7). Cyclohexenone (4), (4R,5S,6R)-6-chloro-4,5-dihydroxy-3-methoxy-5-methylcyclohex-2-enone, inhibited ATP synthesis in freshly lysed spinach chloroplasts from water to MV; it also partly inhibited the basal and uncoupled photosynthetic electron transport, and significantly enhanced the phosphorylating electron transport and Mg 2+ -ATPase activity, thus demonstrating its action as an uncoupler agent. On the other hand, quinone (7), 2-((4-butylphenyl)amino)-5-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione, inhibited ATP synthesis, and non-cyclic electron transport from water to MV in basal, phosphorylating and uncoupled conditions in a concentration-dependent manner. Hence, (7) behaves as a Hill reaction inhibitor at the PSII electron transport on the water splitting enzyme (OEC), and on the acceptor side between P 680 and Q A . This mechanism of action was confirmed by chlorophyll a fluorescence measurements. These results indicate that coriloxine derivatives 4 and 7 could work as prototype structures for the development of new herbicides. Contrastingly, natural products 1-3, and derivatives 5 and 6 did not show a significant inhibitory effect on ATP synthesis. Copyright © 2016 Elsevier B.V. All rights reserved.

Lean phenotype and resistance to diet-induced obesity in vitamin D receptor knockout mice correlates with induction of uncoupling protein-1 in white adipose tissue.

PubMed

Narvaez, Carmen J; Matthews, Donald; Broun, Emily; Chan, Michelle; Welsh, JoEllen

2009-02-01

Increased adiposity is a feature of aging in both mice and humans, but the molecular mechanisms underlying age-related changes in adipose tissue stores remain unclear. In previous studies, we noted that 18-month-old normocalcemic vitamin D receptor (VDR) knockout (VDRKO) mice exhibited atrophy of the mammary adipose compartment relative to wild-type (WT) littermates, suggesting a role for VDR in adiposity. Here we monitored body fat depots, food intake, metabolic factors, and gene expression in WT and VDRKO mice on the C57BL6 and CD1 genetic backgrounds. Regardless of genetic background, both sc and visceral white adipose tissue depots were smaller in VDRKO mice than WT mice. The lean phenotype of VDRKO mice was associated with reduced serum leptin and compensatory increased food intake. Similar effects on adipose tissue, leptin and food intake were observed in mice lacking Cyp27b1, the 1alpha-hydroxylase enzyme that generates 1,25-dihydroxyvitamin D(3), the VDR ligand. Although VDR ablation did not reduce expression of peroxisome proliferator-activated receptor-gamma or fatty acid synthase, PCR array screening identified several differentially expressed genes in white adipose tissue from WT and VDRKO mice. Uncoupling protein-1, which mediates dissociation of cellular respiration from energy production, was greater than 25-fold elevated in VDRKO white adipose tissue. Consistent with elevation in uncoupling protein-1, VDRKO mice were resistant to high-fat diet-induced weight gain. Collectively, these studies identify a novel role for 1,25-dihydroxyvitamin D(3) and the VDR in the control of adipocyte metabolism and lipid storage in vivo.

Effects of maturation-inducing hormone on heterologous gap junctional coupling in ovarian follicles of Atlantic croaker

USGS Publications Warehouse

Yoshizaki, G.; Patino, R.; Thomas, P.; Bolamba, D.; Chang, Xiaotian

2001-01-01

A previous ultrastructural study of heterologous (granulosa cell-oocyte) gap junction (GJ) contacts in ovarian follicles of Atlantic croaker suggested that these contacts disappear late during the process of resumption of oocyte meiosis. This observation suggested that, unlike scenarios proposed for a number of other species, uncoupling of GJ is not necessary for the onset of meiotic resumption in croaker follicles. However, the functionality of heterologous GJ contacts and the temporal association between maturation-inducing hormone (MIH)-induced changes in heterologous coupling and resumption of oocyte meiosis have not been examined in Atlantic croaker. These questions were addressed with a cell-cell coupling assay that is based on the transfer of a GJ marker, Lucifer Yellow, from oocytes to granulosa cells. Follicle-enclosed oocytes injected with Lucifer Yellow allowed transfer of the dye into the follicle cell layer, thus confirming that there is functional heterologous coupling between the oocyte and the granulosa cells. Dye transfer was observed in vitellogenic, full-grown/maturation-incompetent, and full-grown /maturation-competent follicles. Treatment of maturation-competent follicles with MIH caused a time-dependent decline in the number of follicles transferring dye. However, although GJ uncoupling in some of the follicles was observed before germinal vesicle breakdown (GVBD, index of meiotic resumption), about 50% of the follicles maintained the ability to transfer dye even after GVBD had occurred. Further, a known GJ inhibitor (phorbol 12-myristate 13-acetate) blocked heterologous GJ within a time frame similar to that seen with MIH but without inducing any of the morphological changes (including GVBD) associated with follicular maturation. In conclusion, uncoupling of heterologous GJ seems insufficient and unnecessary for the onset of meiotic resumption in ovarian follicles of Atlantic croaker. ?? 2001 Elsevier Science.

Chimera states in a multilayer network of coupled and uncoupled neurons

NASA Astrophysics Data System (ADS)

Majhi, Soumen; Perc, Matjaž; Ghosh, Dibakar

2017-07-01

We study the emergence of chimera states in a multilayer neuronal network, where one layer is composed of coupled and the other layer of uncoupled neurons. Through the multilayer structure, the layer with coupled neurons acts as the medium by means of which neurons in the uncoupled layer share information in spite of the absence of physical connections among them. Neurons in the coupled layer are connected with electrical synapses, while across the two layers, neurons are connected through chemical synapses. In both layers, the dynamics of each neuron is described by the Hindmarsh-Rose square wave bursting dynamics. We show that the presence of two different types of connecting synapses within and between the two layers, together with the multilayer network structure, plays a key role in the emergence of between-layer synchronous chimera states and patterns of synchronous clusters. In particular, we find that these chimera states can emerge in the coupled layer regardless of the range of electrical synapses. Even in all-to-all and nearest-neighbor coupling within the coupled layer, we observe qualitatively identical between-layer chimera states. Moreover, we show that the role of information transmission delay between the two layers must not be neglected, and we obtain precise parameter bounds at which chimera states can be observed. The expansion of the chimera region and annihilation of cluster and fully coherent states in the parameter plane for increasing values of inter-layer chemical synaptic time delay are illustrated using effective range measurements. These results are discussed in the light of neuronal evolution, where the coexistence of coherent and incoherent dynamics during the developmental stage is particularly likely.

Effect of mitochondrial uncoupling and glycolysis inhibition on ram sperm functionality.

PubMed

Losano, Jda; Angrimani, Dsr; Dalmazzo, A; Rui, B R; Brito, M M; Mendes, C M; Kawai, Gkv; Vannucchi, C I; Assumpção, Meoa; Barnabe, V H; Nichi, M

2017-04-01

Studies have demonstrated the importance of mitochondria to sperm functionality, as the main source of ATP for cellular homoeostasis and motility. However, the role of mitochondria on sperm metabolism is still controversial. Studies indicate that, for some species, glycolysis may be the main mechanism for sperm energy production. For ram sperm, such pathway is not clear. Thus, we evaluated ram sperm in response to mitochondrial uncoupling and glycolysis inhibition aiming to assess the importance of each pathway for sperm functionality. Statistical analysis was performed by the SAS System for Windows, using the General Linear Model Procedure. Data were tested for residue normality and variance homogeneity. A p < .05 was considered significant. Groups treated with the mitochondrial uncoupler Carbonyl cyanide 3 chlorophenylhydrazone (CCCP) showed a decrease in the percentage of cells with low mitochondrial activity and high mitochondrial membrane potential. We also observed that the highest CCCP concentration promotes a decrease in sperm susceptibility to lipid peroxidation. Regardless the lack of effect of CCCP on total motility, this substance induced significant alterations on sperm kinetics. Besides the interference of CCCP on spermatic movement patterns, it was also possible to observe such an effect in samples treated with the inhibitor of glycolysis (2-deoxy-d-glucose, DOG). Furthermore, treatment with DOG also led to a dose-dependent increase in sperm susceptibility to lipid peroxidation. Based on our results, we suggest that the glycolysis appears to be as important as oxidative phosphorylation for ovine sperm kinetics as this mechanism is capable of maintaining full motility when most of the cells have a low mitochondrial membrane potential. Furthermore, we found that changes in the glycolytic pathway trough glycolysis inhibition are likely involved in mitochondrial dysfunction and sperm oxidative unbalance. © 2017 Blackwell Verlag GmbH.

Cyanide-induced death of dopaminergic cells is mediated by uncoupling protein-2 up-regulation and reduced Bcl-2 expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, X.; Li, L.; Zhang, L.

Cyanide is a potent inhibitor of mitochondrial oxidative metabolism and produces mitochondria-mediated death of dopaminergic neurons and sublethal intoxications that are associated with a Parkinson-like syndrome. Cyanide toxicity is enhanced when mitochondrial uncoupling is stimulated following up-regulation of uncoupling protein-2 (UCP-2). In this study, the role of a pro-survival protein, Bcl-2, in cyanide-mediated cell death was determined in a rat dopaminergic immortalized mesencephalic cell line (N27 cells). Following pharmacological up-regulation of UCP-2 by treatment with Wy14,643, cyanide reduced cellular Bcl-2 expression by increasing proteasomal degradation of the protein. The increased turnover of Bcl-2 was mediated by an increase of oxidativemore » stress following UCP-2 up-regulation. The oxidative stress involved depletion of mitochondrial glutathione (mtGSH) and increased H{sub 2}O{sub 2} generation. Repletion of mtGSH by loading cells with glutathione ethyl ester reduced H{sub 2}O{sub 2} generation and in turn blocked the cyanide-induced decrease of Bcl-2. To determine if UCP-2 mediated the response, RNAi knock down was conducted. The RNAi decreased cyanide-induced depletion of mtGSH, reduced H{sub 2}O{sub 2} accumulation, and inhibited down-regulation of Bcl-2, thus blocking cell death. To confirm the role of Bcl-2 down-regulation in the cell death, it was shown that over-expression of Bcl-2 by cDNA transfection attenuated the enhancement of cyanide toxicity after UCP-2 up-regulation. It was concluded that UCP-2 up-regulation sensitizes cells to cyanide by increasing cellular oxidative stress, leading to an increase of Bcl-2 degradation. Then the reduced Bcl-2 levels sensitize the cells to cyanide-mediated cell death.« less

Effects of internal and external factors on the budgeting between defensive and non-defensive responses in Aplysia.

PubMed

Leod, Kaitlyn A Mac; Seas, Alexandra; Wainwright, Marcy L; Mozzachiodi, Riccardo

2018-04-25

Following exposure to aversive stimuli, organisms budget their behaviors by augmenting defensive responses and reducing/suppressing non-defensive behaviors. This budgeting process must be flexible to accommodate modifications in the animal's internal and/or external state that require the normal balance between defensive and non-defensive behaviors to be adjusted. When exposed to aversive stimuli, the mollusk Aplysia budgets its behaviors by concurrently enhancing defensive withdrawal reflexes (an elementary form of learning known as sensitization) and suppressing feeding. Sensitization and feeding suppression are consistently co-expressed following different training protocols and share common temporal domains, suggesting that they are interlocked. In this study, we attempted to uncouple the co-expression of sensitization and feeding suppression using: 1) manipulation of the animal's motivational state through prolonged food deprivation and 2) extended training with aversive stimuli that induces sensitization lasting for weeks. Both manipulations uncoupled the co-expression of the above behavioral changes. Prolonged food deprivation prevented the expression of sensitization, but not of feeding suppression. Following the extended training, sensitization and feeding suppression were co-expressed only for a limited time (i.e., 24 h), after which feeding returned to baseline levels as sensitization persisted for up to seven days. These findings indicate that sensitization and feeding suppression are not interlocked and that their co-expression can be uncoupled by internal (prolonged food deprivation) and external (extended aversive training) factors. The different strategies, by which the co-expression of sensitization and feeding suppression was altered, provide an example of how budgeting strategies triggered by an identical aversive experience can vary depending on the state of the organism. Copyright © 2018 Elsevier B.V. All rights reserved.

Dietary effects on body composition, glucose metabolism, and longevity are modulated by skeletal muscle mitochondrial uncoupling in mice

PubMed Central

Keipert, Susanne; Voigt, Anja; Klaus, Susanne

2011-01-01

Little is known about how diet and energy metabolism interact in determination of lifespan under ad libitum feeding. From 12 weeks of age until death, male and female wild-type (WT) and transgenic (TG) mice with increased skeletal muscle mitochondrial uncoupling (HSA-mUCP1 mice) were fed one of three different semisynthetic diets differing in macronutrient ratio: control (high-carbohydrate/low-fat-HCLF) and two high-fat diets: high-carbohydrate/high-fat (HCHF), and low-carbohydrate/high-fat (LCHF). Compared to control and LCHF, HCHF feeding rapidly and significantly increased body fat content in WT. Median lifespan of WT was decreased by 33% (HCHF) and 7% (LCHF) compared to HCLF. HCHF significantly increased insulin resistance (HOMA) of WT from 24 weeks on compared to control. TG mice had lower lean body mass and increased energy expenditure, insulin sensitivity, and maximum lifespan (+10%) compared to WT. They showed a delayed development of obesity on HCHF but reached similar maximum adiposity as WT. TG median lifespan was only slightly reduced by HCHF (−7%) and unaffected by LCHF compared to control. Correlation analyses showed that decreased longevity was more strongly linked to a high rate of fat gain than to adiposity itself. Furthermore, insulin resistance was negatively and weight-specific energy expenditure was positively correlated with longevity. We conclude that (i) dietary macronutrient ratios strongly affected obesity development, glucose homeostasis, and longevity, (ii) that skeletal muscle mitochondrial uncoupling alleviated the detrimental effects of high-fat diets, and (iii) that early imbalances in energy homeostasis leading to increased insulin resistance are predictive for a decreased lifespan. PMID:21070590

The β3 Adrenergic Receptor Agonist BRL37344 Exacerbates Atrial Structural Remodeling Through iNOS Uncoupling in Canine Models of Atrial Fibrillation.

PubMed

Wang, Xiaobing; Wang, Ruifeng; Liu, Guangzhong; Dong, Jingmei; Zhao, Guanqi; Tian, Jingpu; Sun, Jiayu; Jia, Xiuyue; Wei, Lin; Wang, Yuping; Li, Weimin

2016-01-01

The role of the β3-adrenergic receptor (β3-AR) agonist BRL37344 in atrial fibrillation (AF) structural remodeling and the underlying mechanisms as a therapeutic target were investigated. Four groups of dogs were evaluated: sham, pacing, β3-AR agonist BRL37344 (β3-AGO), and β3-AR antagonist L748337 (β3-ANT) groups. Dogs in the pacing, β3-AGO and β3-ANT groups were subjected to rapid atrial pacing for four weeks. Atrial structure and function, AF inducibility and duration, atrial myocyte apoptosis and interstitial fibrosis were assessed. Atrial superoxide anions were evaluated by fluorescence microscopy and colorimetric assays. Cardiac nitrate+nitrite levels were used to assess nitric oxide (NO) production. Protein and mRNA expression of β3-AR, neuronal NO synthase (nNOS), inducible NO synthase (iNOS), endothelial NO synthase (eNOS) and guanosine triphosphate cyclohydrolase-1 (GCH-1) as well as tetrahydrobiopterin (BH4) levels were measured. β3-AR was up-regulated in AF. Stimulation of β3-AR significantly increased atrial myocyte apoptosis, fibrosis and atrial dilatation, resulting in increased AF induction and prolonged duration. These effects were attenuated by β3-ANT. Moreover, β3-AGO reduced BH4 and NO production and increased superoxide production, which was inhibited by the specific iNOS inhibitor, 1400w β3-AGO also increased iNOS but decreased eNOS and had no effect on nNOS expression in AF. β3-AR stimulation resulted in atrial structural remodeling by increasing iNOS uncoupling and related oxidative stress. β3-AR up-regulation and iNOS uncoupling might be underlying AF therapeutic targets. © 2016 The Author(s) Published by S. Karger AG, Basel.

Dietary effects on body composition, glucose metabolism, and longevity are modulated by skeletal muscle mitochondrial uncoupling in mice.

PubMed

Keipert, Susanne; Voigt, Anja; Klaus, Susanne

2011-02-01

Little is known about how diet and energy metabolism interact in determination of lifespan under ad libitum feeding. From 12 weeks of age until death, male and female wild-type (WT) and transgenic (TG) mice with increased skeletal muscle mitochondrial uncoupling (HSA-mUCP1 mice) were fed one of three different semisynthetic diets differing in macronutrient ratio: control (high-carbohydrate/low-fat-HCLF) and two high-fat diets: high-carbohydrate/high-fat (HCHF), and low-carbohydrate/high-fat (LCHF). Compared to control and LCHF, HCHF feeding rapidly and significantly increased body fat content in WT. Median lifespan of WT was decreased by 33% (HCHF) and 7% (LCHF) compared to HCLF. HCHF significantly increased insulin resistance (HOMA) of WT from 24 weeks on compared to control. TG mice had lower lean body mass and increased energy expenditure, insulin sensitivity, and maximum lifespan (+10%) compared to WT. They showed a delayed development of obesity on HCHF but reached similar maximum adiposity as WT. TG median lifespan was only slightly reduced by HCHF (-7%) and unaffected by LCHF compared to control. Correlation analyses showed that decreased longevity was more strongly linked to a high rate of fat gain than to adiposity itself. Furthermore, insulin resistance was negatively and weight-specific energy expenditure was positively correlated with longevity. We conclude that (i) dietary macronutrient ratios strongly affected obesity development, glucose homeostasis, and longevity, (ii) that skeletal muscle mitochondrial uncoupling alleviated the detrimental effects of high-fat diets, and (iii) that early imbalances in energy homeostasis leading to increased insulin resistance are predictive for a decreased lifespan.

The role of spatial organization of Ca2+ release sites in the generation of arrhythmogenic diastolic Ca2+ release in myocytes from failing hearts

PubMed Central

Ho, Hsiang-Ting; Bonilla, Ingrid M.; Terentyeva, Radmila; Schober, Karsten E.; Terentyev, Dmitry; Carnes, Cynthia A.

2018-01-01

In heart failure (HF), dysregulated cardiac ryanodine receptors (RyR2) contribute to the generation of diastolic Ca2+ waves (DCWs), thereby predisposing adrenergically stressed failing hearts to life-threatening arrhythmias. However, the specific cellular, subcellular, and molecular defects that account for cardiac arrhythmia in HF remain to be elucidated. Patch-clamp techniques and confocal Ca2+ imaging were applied to study spatially defined Ca2+ handling in ventricular myocytes isolated from normal (control) and failing canine hearts. Based on their activation time upon electrical stimulation, Ca2+ release sites were categorized as coupled, located in close proximity to the sarcolemmal Ca2+ channels, and uncoupled, the Ca2+ channel-free non-junctional Ca2+ release units. In control myocytes, stimulation of β-adrenergic receptors with isoproterenol (Iso) resulted in a preferential increase in Ca2+ spark rate at uncoupled sites. This site-specific effect of Iso was eliminated by the phosphatase inhibitor okadaic acid, which caused similar facilitation of Ca2+ sparks at coupled and uncoupled sites. Iso-challenged HF myocytes exhibited increased predisposition to DCWs compared to control myocytes. In addition, the overall frequency of Ca2+ sparks was increased in HF cells due to preferential stimulation of coupled sites. Furthermore, coupled sites exhibited accelerated recovery from functional refractoriness in HF myocytes compared to control myocytes. Spatially resolved subcellular Ca2+ mapping revealed that DCWs predominantly originated from coupled sites. Inhibition of CaMK∏ suppressed DCWs and prevented preferential stimulation of coupled sites in Iso-challenged HF myocytes. These results suggest that CaMK∏-(and phosphatase)-dependent dysregulation of junctional Ca2+ release sites contributes to Ca2+-dependent arrhythmogenesis in HF. PMID:28612155

Impact of nitrogen feeding regulation on polyhydroxyalkanoates production by mixed microbial cultures.

PubMed

Silva, Fernando; Campanari, Sabrina; Matteo, Stefania; Valentino, Francesco; Majone, Mauro; Villano, Marianna

2017-07-25

A sequencing batch reactor (SBR) is typically used for selecting mixed microbial cultures (MMC) for polyhydroxyalkanoate (PHA) production. Since many waste streams suitable as process feedstock for PHA production are nitrogen-deficient, a nutrient supply in the SBR is typically required to allow for efficient microbial growth. The scope of this study was to devise a nitrogen feeding strategy which allows controlling the nitrogen levels during the feast and famine regime of a lab-scale SBR, thereby selecting for PHA-storing microorganisms. At the beginning of the cycle the reactor was fed with a synthetic mixture of acetic and propionic acids at an overall organic load rate of 8.5gCODL -1 d -1 (i.e. 260CmmolL -1 d -1 ), whereas nitrogen (in the form of ammonium sulphate) was added either simultaneously to the carbon feed (coupled feeding strategy) or after the end of the feast phase (uncoupled feeding strategy). As a main result, PHA production was more than doubled (up to about 1300±64mgCODL -1 ) when carbon and nitrogen were separately fed and the higher PHA production also corresponded to an 82% increase in the polymer HV content (up to 20±1%, wtwt -1 ). Three SBR runs were performed with the uncoupled carbon and nitrogen feeding at different carbon to nitrogen (C/N) ratios (of 14.3, 17.9, and 22.3CmolNmol -1 , respectively) which were varied by progressively reducing the concentration of the nitrogen feeding. In spite of a comparable PHA storage yield at 14.3 and 17.9CmolNmol -1 (0.41±0.05 gCOD PHA gCOD VFA -1 and 0.38±0.05 gCOD PHA gCOD VFA -1 , respectively), the storage response of the selected MMC significantly decreased when the C/N ratio was set at the highest investigated value. Notably, an increase in this parameter also resulted in a change in the HV content in the polymer regardless the composition of the organic acids solution. Copyright © 2016 Elsevier B.V. All rights reserved.

The role of mitochondria in protection of the heart by preconditioning

PubMed Central

Halestrap, Andrew P.; Clarke, Samantha J.; Khaliulin, Igor

2007-01-01

A prolonged period of ischaemia followed by reperfusion irreversibly damages the heart. Such reperfusion injury (RI) involves opening of the mitochondrial permeability transition pore (MPTP) under the conditions of calcium overload and oxidative stress that accompany reperfusion. Protection from MPTP opening and hence RI can be mediated by ischaemic preconditioning (IP) where the prolonged ischaemic period is preceded by one or more brief (2–5 min) cycles of ischaemia and reperfusion. Following a brief overview of the molecular characterisation and regulation of the MPTP, the proposed mechanisms by which IP reduces pore opening are reviewed including the potential roles for reactive oxygen species (ROS), protein kinase cascades, and mitochondrial potassium channels. It is proposed that IP-mediated inhibition of MPTP opening at reperfusion does not involve direct phosphorylation of mitochondrial proteins, but rather reflects diminished oxidative stress during prolonged ischaemia and reperfusion. This causes less oxidation of critical thiol groups on the MPTP that are known to sensitise pore opening to calcium. The mechanisms by which ROS levels are decreased in the IP hearts during prolonged ischaemia and reperfusion are not known, but appear to require activation of protein kinase Cε, either by receptor-mediated events or through transient increases in ROS during the IP protocol. Other signalling pathways may show cross-talk with this primary mechanism, but we suggest that a role for mitochondrial potassium channels is unlikely. The evidence for their activity in isolated mitochondria and cardiac myocytes is reviewed and the lack of specificity of the pharmacological agents used to implicate them in IP is noted. Some K+ channel openers uncouple mitochondria and others inhibit respiratory chain complexes, and their ability to produce ROS and precondition hearts is mimicked by bona fide uncouplers and respiratory chain inhibitors. IP may also provide continuing protection during reperfusion by preventing a cascade of MPTP-induced ROS production followed by further MPTP opening. This phase of protection may involve survival kinase pathways such as Akt and glycogen synthase kinase 3 (GSK3) either increasing ROS removal or reducing mitochondrial ROS production. PMID:17631856

Blockade of brain stem gap junctions increases phrenic burst frequency and reduces phrenic burst synchronization in adult rat.

PubMed

Solomon, Irene C; Chon, Ki H; Rodriguez, Melissa N

2003-01-01

Recent investigations have examined the influence of gap junctional communication on generation and modulation of respiratory rhythm and inspiratory motoneuron synchronization in vitro using transverse medullary slice and en bloc brain stem-spinal cord preparations obtained from neonatal (1-5 days postnatal) mice. Gap junction proteins, however, have been identified in both neurons and glia in brain stem regions implicated in respiratory control in both neonatal and adult rodents. Here, we used an in vitro arterially perfused rat preparation to examine the role of gap junctional communication on generation and modulation of respiratory rhythm and inspiratory motoneuron synchronization in adult rodents. We recorded rhythmic inspiratory motor activity from one or both phrenic nerves before and during pharmacological blockade (i.e., uncoupling) of brain stem gap junctions using carbenoxolone (100 microM), 18alpha-glycyrrhetinic acid (25-100 microM), 18beta-glycyrrhetinic acid (25-100 microM), octanol (200-300 microM), or heptanol (200 microM). During perfusion with a gap junction uncoupling agent, we observed an increase in the frequency of phrenic bursts (~95% above baseline frequency; P < 0.001) and a decrease in peak amplitude of integrated phrenic nerve discharge (P < 0.001). The increase in frequency of phrenic bursts resulted from a decrease in both T(I) (P < 0.01) and T(E) (P < 0.01). In addition, the pattern of phrenic nerve discharge shifted from an augmenting discharge pattern to a "bell-shaped" or square-wave discharge pattern in most experiments. Spectral analyses using a fast Fourier transform (FFT) algorithm revealed a reduction in the peak power of both the 40- to 50-Hz peak (corresponding to the MFO) and 90- to 110-Hz peak (corresponding to the HFO) although spurious higher frequency activity (> or =130 Hz) was observed, suggesting an overall loss or reduction in inspiratory-phase synchronization. Although additional experiments are required to identify the specific brain stem regions and cell types (i.e., neurons, glia) mediating the observed modulations in phrenic motor output, these findings suggest that gap junction communication modulates generation of respiratory rhythm and inspiratory motoneuron synchronization in adult rodents in vitro.

Stabilization of cartwheel-less centrioles for duplication requires CEP295-mediated centriole-to-centrosome conversion.

PubMed

Izquierdo, Denisse; Wang, Won-Jing; Uryu, Kunihiro; Tsou, Meng-Fu Bryan

2014-08-21

Vertebrate centrioles lose their geometric scaffold, the cartwheel, during mitosis, concurrently with gaining the ability to recruit the pericentriolar material (PCM) and thereby function as the centrosome. Cartwheel removal has recently been implicated in centriole duplication, but whether "cartwheel-less" centrioles are intrinsically stable or must be maintained through other modifications remains unclear. Here, we identify a newborn centriole-enriched protein, KIAA1731/CEP295, specifically mediating centriole-to-centrosome conversion but dispensable for cartwheel removal. In the absence of CEP295, centrioles form in the S/G2 phase and lose their associated cartwheel in mitosis but cannot be converted to centrosomes, uncoupling the two events. Strikingly, centrioles devoid of both the PCM and the cartwheel progressively lose centriolar components, whereas centrioles associating with either the cartwheel or PCM alone can exist stably. Thus, cartwheel removal can have grave repercussions to centriole stability, and centriole-to-centrosome conversion mediated by CEP295 must occur in parallel to maintain cartwheel-less centrioles for duplication. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

DNA damage and polyploidization.

PubMed

Chow, Jeremy; Poon, Randy Y C

2010-01-01

A growing body of evidence indicates that polyploidization triggers chromosomal instability and contributes to tumorigenesis. DNA damage is increasingly being recognized for its roles in promoting polyploidization. Although elegant mechanisms known as the DNA damage checkpoints are responsible for halting the cell cycle after DNA damage, agents that uncouple the checkpoints can induce unscheduled entry into mitosis. Likewise, defects of the checkpoints in several disorders permit mitotic entry even in the presence of DNA damage. Forcing cells with damaged DNA into mitosis causes severe chromosome segregation defects, including lagging chromosomes, chromosomal fragments and chromosomal bridges. The presence of these lesions in the cleavage plane is believed to abort cytokinesis. It is postulated that if cytokinesis failure is coupled with defects of the p53-dependent postmitotic checkpoint pathway, cells can enter S phase and become polyploids. Progress in the past several years has unraveled some of the underlying principles of these pathways and underscored the important role of DNA damage in polyploidization. Furthermore, polyploidization per se may also be an important determinant of sensitivity to DNA damage, thereby may offer an opportunity for novel therapies.

Two-dimensional displacement measurement based on two parallel gratings

NASA Astrophysics Data System (ADS)

Wei, Peipei; Lu, Xi; Qiao, Decheng; Zou, Limin; Huang, Xiangdong; Tan, Jiubin; Lu, Zhengang

2018-06-01

In this paper, a two-dimensional (2-D) planar encoder based on two parallel gratings, which includes a scanning grating and scale grating, is presented. The scanning grating is a combined transmission rectangular grating comprised of a 2-D grating located at the center and two one-dimensional (1-D) gratings located at the sides. The grating lines of the two 1-D gratings are perpendicular to each other and parallel with the 2-D grating lines. The scale grating is a 2-D reflective-type rectangular grating placed in parallel with the scanning grating, and there is an angular difference of 45° between the grating lines of the two 2-D gratings. With the special structural design of the scanning grating, the encoder can measure the 2-D displacement in the grating plane simultaneously, and the measured interference signals in the two directions are uncoupled. Moreover, by utilizing the scanning grating to modulate the phase of the interference signals instead of the prisms, the structure of the encoder is compact. Experiments were implemented, and the results demonstrate the validity of the 2-D planar grating encoder.

Suppressing turbulence of self-propelling rods by strongly coupled passive particles.

PubMed

Su, Yen-Shuo; Wang, Hao-Chen; I, Lin

2015-03-01

The strong turbulence suppression, mainly for large-scale modes, of two-dimensional self-propelling rods, by increasing the long-range coupling strength Γ of low-concentration passive particles, is numerically demonstrated. It is found that large-scale collective rod motion in forms of swirls or jets is mainly contributed from well-aligned dense patches, which can push small poorly aligned rod patches and uncoupled passive particles. The more efficient momentum transfer and dissipation through increasing passive particle coupling leads to the formation of a more ordered and slowed down network of passive particles, which competes with coherent dense active rod clusters. The frustration of active rod alignment ordering and coherent motion by the passive particle network, which interrupt the inverse cascading of forming large-scale swirls, is the key for suppressing collective rod motion with scales beyond the interpassive distance, even in the liquid phase of passive particles. The loosely packed active rods are weakly affected by increasing passive particle coupling due to the weak rod-particle interaction. They mainly contribute to the small-scale modes and high-speed motion.

Differential effects of p,p'-DDE on testis and liver mitochondria: implications for reproductive toxicology.

PubMed

Mota, Paula C; Cordeiro, Marília; Pereira, Susana P; Oliveira, Paulo J; Moreno, António J; Ramalho-Santos, João

2011-01-01

The release of environmental contaminants can contribute to impaired male fertility. The bioenergetics of isolated liver mitochondria have been used as a toxicological indicator, an inexpensive first line model to screen possible effects of several substances. Here we report the effects of 2,2-bis(4-chlorophenyl)-1,1-dichloro-ethylene (DDE) on the bioenergetical parameters of testicular mitochondria. A significant decrease in repolarization potential (after a phosphorylative cycle), state 3 respiration and uncoupled respiration, with a concomitant increase in lag phase was found, demonstrating a decrease in mitochondrial function. Importantly, there was also a clear increase in maximum potential in DDE-treated testis mitochondria, which was not mirrored by more commonly used liver mitochondria. Indeed, comparative studies showed that testis and liver mitochondria have strikingly different sensitivities and patterns of response to DDE, indicating that testis mitochondria should be used as a primary toxicological model for a proper evaluation of putative effects of environmental toxicants on the bioenergetics of spermatogenesis and male fertility. Copyright © 2010 Elsevier Inc. All rights reserved.

Evidence for involvement of nonesterified fatty acid-induced protonophoric uncoupling during mitochondrial dysfunction caused by hypoxia and reoxygenation

PubMed Central

Feldkamp, Thorsten; Weinberg, Joel M.; Hörbelt, Markus; Von Kropff, Christina; Witzke, Oliver; Nürnberger, Jens; Kribben, Andreas

2009-01-01

Background. Proximal tubules subjected to hypoxia in vitro under conditions relevant to ischaemia in vivo develop an energetic deficit that is not corrected even after full reoxygenation. We have provided evidence that accumulation of nonesterified fatty acids (NEFA) is the primary reason for this energetic deficit. In this study, we have further investigated the mechanism for the NEFA-induced energetic deficit. Methods. Mitochondrial membrane potential (Δψ) was measured in digitonin-permeabilized, freshly isolated proximal tubules by safranin O uptake. Addition of the potassium/proton exchanger nigericin enables the determination of the mitochondrial proton motive force (Δp) and the proton gradient (ΔpH). ATP was measured luminometrically and NEFA colorimetrically. Results. Tubule ATP content was depleted after hypoxia and recovered incompletely, even after full reoxygenation. Mitochondrial safranin O uptake was decreased in proximal tubules after hypoxia and reoxygenation (H/R). This decrease was attenuated by delipidated bovine serum albumin (dBSA) or citrate. Addition of nigericin increased safranin O uptake of mitochondria in normoxic proximal tubules, but not in proximal tubules after H/R. Addition of dBSA restored the effect of nigericin to increase mitochondrial safranin O uptake. Addition of the NEFA oleate had the same impact on mitochondrial safranin O uptake as subjecting proximal tubules to H/R. Conclusion. The mechanism of the NEFA-induced energetic deficit in freshly isolated rat proximal tubules induced by H/R is characterized by impaired ATP production after full reoxygenation, impaired recovery of Δψ and Δp, abrogation of ΔpH and sensitivity to citrate, consistent with involvement of the tricarboxylate carrier. The data support the concept that protonophoric uncoupling by NEFA movement on anion carriers plays a critical role in proximal tubule mitochochondrial dysfunction after H/R. PMID:18678559

Baroreflex Coupling Assessed by Cross-Compression Entropy

PubMed Central

Schumann, Andy; Schulz, Steffen; Voss, Andreas; Scharbrodt, Susann; Baumert, Mathias; Bär, Karl-Jürgen

2017-01-01

Estimating interactions between physiological systems is an important challenge in modern biomedical research. Here, we explore a new concept for quantifying information common in two time series by cross-compressibility. Cross-compression entropy (CCE) exploits the ZIP data compression algorithm extended to bivariate data analysis. First, time series are transformed into symbol vectors. Symbols of the target time series are coded by the symbols of the source series. Uncoupled and linearly coupled surrogates were derived from cardiovascular recordings of 36 healthy controls obtained during rest to demonstrate suitability of this method for assessing physiological coupling. CCE at rest was compared to that of isometric handgrip exercise. Finally, spontaneous baroreflex interaction assessed by CCEBRS was compared between 21 patients suffering from acute schizophrenia and 21 matched controls. The CCEBRS of original time series was significantly higher than in uncoupled surrogates in 89% of the subjects and higher than in linearly coupled surrogates in 47% of the subjects. Handgrip exercise led to sympathetic activation and vagal inhibition accompanied by reduced baroreflex sensitivity. CCEBRS decreased from 0.553 ± 0.030 at rest to 0.514 ± 0.035 during exercise (p < 0.001). In acute schizophrenia, heart rate, and blood pressure were elevated. Heart rate variability indicated a change of sympathovagal balance. The CCEBRS of patients with schizophrenia was reduced compared to healthy controls (0.546 ± 0.042 vs. 0.507 ± 0.046, p < 0.01) and revealed a decrease of blood pressure influence on heart rate in patients with schizophrenia. Our results indicate that CCE is suitable for the investigation of linear and non-linear coupling in cardiovascular time series. CCE can quantify causal interactions in short, noisy and non-stationary physiological time series. PMID:28539889

Loss of Intralipid®- but Not Sevoflurane-Mediated Cardioprotection in Early Type-2 Diabetic Hearts of Fructose-Fed Rats: Importance of ROS Signaling

PubMed Central

Zhang, Liyan; Affolter, Andreas; Gandhi, Manoj; Hersberger, Martin; Warren, Blair E.; Lemieux, Hélène; Sobhi, Hany F.; Clanachan, Alexander S.; Zaugg, Michael

2014-01-01

Background Insulin resistance and early type-2 diabetes are highly prevalent. However, it is unknown whether Intralipid® and sevoflurane protect the early diabetic heart against ischemia-reperfusion injury. Methods Early type-2 diabetic hearts from Sprague-Dawley rats fed for 6 weeks with fructose were exposed to 15 min of ischemia and 30 min of reperfusion. Intralipid® (1%) was administered at the onset of reperfusion. Peri-ischemic sevoflurane (2 vol.-%) served as alternative protection strategy. Recovery of left ventricular function was recorded and the activation of Akt and ERK 1/2 was monitored. Mitochondrial function was assessed by high-resolution respirometry and mitochondrial ROS production was measured by Amplex Red and aconitase activity assays. Acylcarnitine tissue content was measured and concentration-response curves of complex IV inhibition by palmitoylcarnitine were obtained. Results Intralipid® did not exert protection in early diabetic hearts, while sevoflurane improved functional recovery. Sevoflurane protection was abolished by concomitant administration of the ROS scavenger N-2-mercaptopropionyl glycine. Sevoflurane, but not Intralipid® produced protective ROS during reperfusion, which activated Akt. Intralipid® failed to inhibit respiratory complex IV, while sevoflurane inhibited complex I. Early diabetic hearts exhibited reduced carnitine-palmitoyl-transferase-1 activity, but palmitoylcarnitine could not rescue protection and enhance postischemic functional recovery. Cardiac mitochondria from early diabetic rats exhibited an increased content of subunit IV-2 of respiratory complex IV and of uncoupling protein-3. Conclusions Early type-2 diabetic hearts lose complex IV-mediated protection by Intralipid® potentially due to a switch in complex IV subunit expression and increased mitochondrial uncoupling, but are amenable to complex I-mediated sevoflurane protection. PMID:25127027

Alteration in cardiac uncoupling proteins and eNOS gene expression following high-intensity interval training in favor of increasing mechanical efficiency

PubMed Central

Fallahi, Ali Asghar; Shekarfroush, Shahnaz; Rahimi, Mostafa; Jalali, Amirhossain; Khoshbaten, Ali

2016-01-01

Objective(s): High-intensity interval training (HIIT) increases energy expenditure and mechanical energy efficiency. Although both uncoupling proteins (UCPs) and endothelial nitric oxide synthase (eNOS) affect the mechanical efficiency and antioxidant capacity, their effects are inverse. The aim of this study was to determine whether the alterations of cardiac UCP2, UCP3, and eNOS mRNA expression following HIIT are in favor of increased mechanical efficiency or decreased oxidative stress. Materials and Methods: Wistar rats were divided into five groups: control group (n=12), HIIT for an acute bout (AT1), short term HIIT for 3 and 5 sessions (ST3 and ST5), long-term training for 8 weeks (LT) (6 in each group). The rats of the training groups were made to run on a treadmill for 60 min in three stages: 6 min running for warm-up, 7 intervals of 7 min running on treadmill with a slope of 5° to 20° (4 min with an intensity of 80-110% VO2max and 3 min at 50-60% VO2max), and 5-min running for cool-down. The control group did not participate in any exercise program. Rats were sacrificed and the hearts were extracted to analyze the levels of UCP2, UCP3 and eNOS mRNA by RT-PCR. Results: UCP3 expression was increased significantly following an acute training bout. Repeated HIIT for 8 weeks resulted in a significant decrease in UCPs mRNA and a significant increase in eNOS expression in cardiac muscle. Conclusion: This study indicates that Long term HIIT through decreasing UCPs mRNA and increasing eNOS mRNA expression may enhance energy efficiency and physical performance. PMID:27114795

Uncoupling protein 2 gene polymorphisms are associated with obesity

PubMed Central

2012-01-01

Background Uncoupling protein 2 (UCP2) gene polymorphisms have been reported as genetic risk factors for obesity and type 2 diabetes mellitus (T2DM). We examined the association of commonly observed UCP2 G(−866)A (rs659366) and Ala55Val (C > T) (rs660339) single nucleotide polymorphisms (SNPs) with obesity, high fasting plasma glucose, and serum lipids in a Balinese population. Methods A total of 603 participants (278 urban and 325 rural subjects) were recruited from Bali Island, Indonesia. Fasting plasma glucose (FPG), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) were measured. Obesity was determined based on WHO classifications for adult Asians. Participants were genotyped for G(−866)A and Ala55Val polymorphisms of the UCP2 gene. Results Obesity prevalence was higher in urban subjects (51%) as compared to rural subjects (23%). The genotype, minor allele (MAF), and heterozygosity frequencies were similar between urban and rural subjects for both SNPs. All genotype frequencies were in Hardy-Weinberg equilibrium. A combined analysis of genotypes and environment revealed that the urban subjects carrying the A/A genotype of the G(−866)A SNP have higher BMI than the rural subjects with the same genotype. Since the two SNPs showed strong linkage disequilibrium (D’ = 0.946, r2 = 0.657), a haplotype analysis was performed. We found that the AT haplotype was associated with high BMI only when the urban environment was taken into account. Conclusions We have demonstrated the importance of environmental settings in studying the influence of the common UCP2 gene polymorphisms in the development of obesity in a Balinese population. PMID:22533685

Local pharmacological effects of tungstate on the color-pattern determination of butterfly wings: a possible relationship between the eyespot and parafocal element.

PubMed

Dhungel, Bidur; Otaki, Joji M

2009-11-01

Butterfly wing color patterns can be changed by the application of a temperature shock or pharmacological agents such as tungstate, producing a distinctive type of elemental modification called the TS (temperature shock) type. Heterochronic uncoupling between the signaling and reception steps during the color-pattern determination process has been proposed as a mechanism for TS-type changes. As an extension of this hypothesis, both the parafocal element (PFE) and the eyespot in the same wing compartment are considered to be determined by morphogenic signal(s) emitted from the same eyespot focus. However, these models need to be examined with additional experimental data. Furthermore, there is controversy as to whether the action of tungstate on wing color patterns is direct or Indirect. Using a species of nymphalid butterfly (Junonia orithya), we have devised a simple method for the local application of pharmacological agents directly on developing wings of pupae. Local tungstate application resulted in reduced eyespots and circular dislocated PFEs in the eyespot-less compartments only on the treated wing, demonstrating that tungstate directly induces color-pattern changes on wings. We further examined the eyespot-PFE relationship in normal and cold-shocked Individuals, showing that an eyespot can be superimposed on a PFE and vice versa, probably depending on the timing of their fate determination. Taken together, we propose a two-morphogen model for the normal color-pattern determination, in which the morphogenic signals for the eyespot and PFE are different from each other despite their Identical origin. This two-morphogen model is compatible with the heterochronic uncoupling model for TS-type changes.

Design and characterization of the first peptidomimetic molecule that prevents acidification-induced closure of cardiac gap junctions

PubMed Central

Verma, Vandana; Larsen, Bjarne Due; Coombs, Wanda; Lin, Xianming; Sarrou, Eliana; Taffet, Steven M.; Delmar, Mario

2010-01-01

Background Gap junctions are potential targets for pharmacological intervention. We have previously developed a series of peptide sequences that prevent closure of Cx43 channels, bind to cardiac Cx43 and prevent acidification-induced uncoupling of cardiac gap junctions. Objective We aimed to identify and validate the minimum core active structure in peptides containing an RR-N/Q-Y motif. Based on that information, we sought to generate a peptidomimetic molecule that acts on the chemical regulation of Cx43 channels. Methods Experiments were based on a combination of biochemical, spectroscopic and electrophysiological techniques, as well as molecular modeling of active pharmacophores with Cx43 activity. Results Molecular modeling analysis indicated that the functional elements of the side chains in the motif RRXY form a triangular structure. Experimental data revealed that compounds containing such a structure bind to Cx43 and prevent Cx43 chemical gating. These results provided us with the first platform for drug design targeted to the carboxyl terminal of Cx43. Using that platform, we designed and validated a peptidomimetic compound (ZP2519; molecular weight 619 Da) that prevented octanol-induced uncoupling of Cx43 channels, and pH gating of cardiac gap junctions. Conclusion Structure-based drug design can be applied to the development of pharmacophores that act directly on Cx43. Small molecules containing these pharmacophores can serve as tools to determine the role of gap junction regulation in the control of cardiac rhythm. Future studies will determine whether these compounds can function as pharmacological agents for the treatment of a selected subset of cardiac arrhythmias. PMID:20601149