Sample records for maximum cell density

  1. The Maximum Density of Water.

    Greenslade, Thomas B., Jr.


    Discusses a series of experiments performed by Thomas Hope in 1805 which show the temperature at which water has its maximum density. Early data cast into a modern form as well as guidelines and recent data collected from the author provide background for duplicating Hope's experiments in the classroom. (JN)

  2. A mathematical model of the maximum power density attainable in an alkaline hydrogen/oxygen fuel cell

    Kimble, Michael C.; White, Ralph E.


    A mathematical model of a hydrogen/oxygen alkaline fuel cell is presented that can be used to predict the polarization behavior under various power loads. The major limitations to achieving high power densities are indicated and methods to increase the maximum attainable power density are suggested. The alkaline fuel cell model describes the phenomena occurring in the solid, liquid, and gaseous phases of the anode, separator, and cathode regions based on porous electrode theory applied to three phases. Fundamental equations of chemical engineering that describe conservation of mass and charge, species transport, and kinetic phenomena are used to develop the model by treating all phases as a homogeneous continuum.

  3. Minimal Length, Friedmann Equations and Maximum Density

    Awad, Adel


    Inspired by Jacobson's thermodynamic approach[gr-qc/9504004], Cai et al [hep-th/0501055,hep-th/0609128] have shown the emergence of Friedmann equations from the first law of thermodynamics. We extend Akbar--Cai derivation [hep-th/0609128] of Friedmann equations to accommodate a general entropy-area law. Studying the resulted Friedmann equations using a specific entropy-area law, which is motivated by the generalized uncertainty principle (GUP), reveals the existence of a maximum energy density closed to Planck density. Allowing for a general continuous pressure $p(\\rho,a)$ leads to bounded curvature invariants and a general nonsingular evolution. In this case, the maximum energy density is reached in a finite time and there is no cosmological evolution beyond this point which leaves the big bang singularity inaccessible from a spacetime prospective. The existence of maximum energy density and a general nonsingular evolution is independent of the equation of state and the spacial curvature $k$. As an example w...


    methods. A test on a soil of relatively high solid density revealed that the developed relation looses ... where, Pd max is the laboratory maximum dry ... Addis-Jinima Road Rehabilitation. ..... data sets that differ considerably in the magnitude.

  5. Maximum length scale in density based topology optimization

    Lazarov, Boyan Stefanov; Wang, Fengwen


    The focus of this work is on two new techniques for imposing maximum length scale in topology optimization. Restrictions on the maximum length scale provide designers with full control over the optimized structure and open possibilities to tailor the optimized design for broader range...... of manufacturing processes by fulfilling the associated technological constraints. One of the proposed methods is based on combination of several filters and builds on top of the classical density filtering which can be viewed as a low pass filter applied to the design parametrization. The main idea...

  6. Maximum likelihood estimation for semiparametric density ratio model.

    Diao, Guoqing; Ning, Jing; Qin, Jing


    In the statistical literature, the conditional density model specification is commonly used to study regression effects. One attractive model is the semiparametric density ratio model, under which the conditional density function is the product of an unknown baseline density function and a known parametric function containing the covariate information. This model has a natural connection with generalized linear models and is closely related to biased sampling problems. Despite the attractive features and importance of this model, most existing methods are too restrictive since they are based on multi-sample data or conditional likelihood functions. The conditional likelihood approach can eliminate the unknown baseline density but cannot estimate it. We propose efficient estimation procedures based on the nonparametric likelihood. The nonparametric likelihood approach allows for general forms of covariates and estimates the regression parameters and the baseline density simultaneously. Therefore, the nonparametric likelihood approach is more versatile than the conditional likelihood approach especially when estimation of the conditional mean or other quantities of the outcome is of interest. We show that the nonparametric maximum likelihood estimators are consistent, asymptotically normal, and asymptotically efficient. Simulation studies demonstrate that the proposed methods perform well in practical settings. A real example is used for illustration.

  7. Maximum entropy reconstruction of spin densities involving non uniform prior

    Schweizer, J.; Ressouche, E. [DRFMC/SPSMS/MDN CEA-Grenoble (France); Papoular, R.J. [CEA-Saclay, Gif sur Yvette (France). Lab. Leon Brillouin; Tasset, F. [Inst. Laue Langevin, Grenoble (France); Zheludev, A.I. [Brookhaven National Lab., Upton, NY (United States). Physics Dept.


    Diffraction experiments give microscopic information on structures in crystals. A method which uses the concept of maximum of entropy (MaxEnt), appears to be a formidable improvement in the treatment of diffraction data. This method is based on a bayesian approach: among all the maps compatible with the experimental data, it selects that one which has the highest prior (intrinsic) probability. Considering that all the points of the map are equally probable, this probability (flat prior) is expressed via the Boltzman entropy of the distribution. This method has been used for the reconstruction of charge densities from X-ray data, for maps of nuclear densities from unpolarized neutron data as well as for distributions of spin density. The density maps obtained by this method, as compared to those resulting from the usual inverse Fourier transformation, are tremendously improved. In particular, any substantial deviation from the background is really contained in the data, as it costs entropy compared to a map that would ignore such features. However, in most of the cases, before the measurements are performed, some knowledge exists about the distribution which is investigated. It can range from the simple information of the type of scattering electrons to an elaborate theoretical model. In these cases, the uniform prior which considers all the different pixels as equally likely, is too weak a requirement and has to be replaced. In a rigorous bayesian analysis, Skilling has shown that prior knowledge can be encoded into the Maximum Entropy formalism through a model m({rvec r}), via a new definition for the entropy given in this paper. In the absence of any data, the maximum of the entropy functional is reached for {rho}({rvec r}) = m({rvec r}). Any substantial departure from the model, observed in the final map, is really contained in the data as, with the new definition, it costs entropy. This paper presents illustrations of model testing.

  8. Exploring high-density baryonic matter: Maximum freeze-out density

    Randrup, Joergen [Lawrence Berkeley National Laboratory, Nuclear Science Division, Berkeley, CA (United States); Cleymans, Jean [University of Cape Town, UCT-CERN Research Centre and Department of Physics, Rondebosch (South Africa)


    The hadronic freeze-out line is calculated in terms of the net baryon density and the energy density instead of the usual T and μ{sub B}. This analysis makes it apparent that the freeze-out density exhibits a maximum as the collision energy is varied. This maximum freeze-out density has μ{sub B} = 400 - 500 MeV, which is above the critical value, and it is reached for a fixed-target bombarding energy of 20-30 GeV/N well within the parameters of the proposed NICA collider facility. (orig.)

  9. Thermospheric density model biases at the 23rd sunspot maximum

    Pardini, C.; Moe, K.; Anselmo, L.


    Uncertainties in the neutral density estimation are the major source of aerodynamic drag errors and one of the main limiting factors in the accuracy of the orbit prediction and determination process at low altitudes. Massive efforts have been made over the years to constantly improve the existing operational density models, or to create even more precise and sophisticated tools. Special attention has also been paid to research more appropriate solar and geomagnetic indices. However, the operational models still suffer from weakness. Even if a number of studies have been carried out in the last few years to define the performance improvements, further critical assessments are necessary to evaluate and compare the models at different altitudes and solar activity conditions. Taking advantage of the results of a previous study, an investigation of thermospheric density model biases during the last sunspot maximum (October 1999 - December 2002) was carried out by analyzing the semi-major axis decay of four satellites: Cosmos 2265, Cosmos 2332, SNOE and Clementine. Six thermospheric density models, widely used in spacecraft operations, were analyzed: JR-71, MSISE-90, NRLMSISE-00, GOST-2004, JB2006 and JB2008. During the time span considered, for each satellite and atmospheric density model, a fitted drag coefficient was solved for and then compared with the calculated physical drag coefficient. It was therefore possible to derive the average density biases of the thermospheric models during the maximum of the 23rd solar cycle. Below 500 km, all the models overestimated the average atmospheric density by amounts varying between +7% and +20%. This was an inevitable consequence of constructing thermospheric models from density data obtained by assuming a fixed drag coefficient, independent of altitude. Because the uncertainty affecting the drag coefficient measurements was about 3% at both 200 km and 480 km of altitude, the calculated air density biases below 500 km were

  10. Design of immuno-enzymosomes with maximum enzyme targeting capability : effect of the enzyme density on the enzyme targeting capability and cell binding properties

    Fonseca, MJ; Haisma, HJ; Klaasen, S; Vingerhoeds, MH; Storm, G


    Immuno-enzymosomes have been proposed for the targeting of enzymes to cancer cells to achieve site specific activation of anticancer prodrugs. Previously, we reported that the enzyme beta-glucuronidase (GUS), capable of activating anthracycline-glucuronide prodrugs, can be coupled to the surface of

  11. 40 CFR 1042.140 - Maximum engine power, displacement, power density, and maximum in-use engine speed.


    ... as specified in 40 CFR 1065.610. This is the maximum in-use engine speed used for calculating the NOX... procedures of 40 CFR part 1065, based on the manufacturer's design and production specifications for the..., power density, and maximum in-use engine speed. 1042.140 Section 1042.140 Protection of...

  12. Unification of Field Theory and Maximum Entropy Methods for Learning Probability Densities

    Kinney, Justin B


    Bayesian field theory and maximum entropy are two methods for learning smooth probability distributions (a.k.a. probability densities) from finite sampled data. Both methods were inspired by statistical physics, but the relationship between them has remained unclear. Here I show that Bayesian field theory subsumes maximum entropy density estimation. In particular, the most common maximum entropy methods are shown to be limiting cases of Bayesian inference using field theory priors that impose no boundary conditions on candidate densities. This unification provides a natural way to test the validity of the maximum entropy assumption on one's data. It also provides a better-fitting nonparametric density estimate when the maximum entropy assumption is rejected.

  13. Maximum flux density of the gyrosynchrotron spectrum in a nonuniform source

    Ai-Hua Zhou; Rong-Chuan Wang; Cheng-Wen Shao


    The maximum flux density of a gyrosynchrotron radiation spectrum in a mag- netic dip|oe model with self absorption and gyroresonance is calculated. Our calculations show that the maximum flux density of the gyrosynchrotron spectrum increases with in- creasing low-energy cutoff, number density, input depth of energetic electrons, magnetic field strength and viewing angle, and with decreasing energy spectral index of energetic electrons, number density and temperature of thermal electrons. It is found that there are linear correlations between the logarithms of the maximum flux density and the above eight parameters with correlation coefficients higher than 0.91 and fit accuracies better than 10%. The maximum flux density could be a good indicator of the changes of these source parameters. In addition, we find that there are very good positive linear correla- tions between the logarithms of the maximum flux density and peak frequency when the above former five parameters vary respectively. Their linear correlation coefficients are higher than 0.90 and the fit accuracies are better than 0.5%.

  14. Constructing valid density matrices on an NMR quantum information processor via maximum likelihood estimation

    Singh, Harpreet; Arvind; Dorai, Kavita, E-mail:


    Estimation of quantum states is an important step in any quantum information processing experiment. A naive reconstruction of the density matrix from experimental measurements can often give density matrices which are not positive, and hence not physically acceptable. How do we ensure that at all stages of reconstruction, we keep the density matrix positive? Recently a method has been suggested based on maximum likelihood estimation, wherein the density matrix is guaranteed to be positive definite. We experimentally implement this protocol on an NMR quantum information processor. We discuss several examples and compare with the standard method of state estimation. - Highlights: • State estimation using maximum likelihood method was performed on an NMR quantum information processor. • Physically valid density matrices were obtained every time in contrast to standard quantum state tomography. • Density matrices of several different entangled and separable states were reconstructed for two and three qubits.

  15. Scaling of maximum probability density functions of velocity and temperature increments in turbulent systems

    Huang, Y X; Zhou, Q; Qiu, X; Shang, X D; Lu, Z M; Liu, and Y L


    In this paper, we introduce a new way to estimate the scaling parameter of a self-similar process by considering the maximum probability density function (pdf) of tis increments. We prove this for $H$-self-similar processes in general and experimentally investigate it for turbulent velocity and temperature increments. We consider turbulent velocity database from an experimental homogeneous and nearly isotropic turbulent channel flow, and temperature data set obtained near the sidewall of a Rayleigh-B\\'{e}nard convection cell, where the turbulent flow is driven by buoyancy. For the former database, it is found that the maximum value of increment pdf $p_{\\max}(\\tau)$ is in a good agreement with lognormal distribution. We also obtain a scaling exponent $\\alpha\\simeq 0.37$, which is consistent with the scaling exponent for the first-order structure function reported in other studies. For the latter one, we obtain a scaling exponent $\\alpha_{\\theta}\\simeq0.33$. This index value is consistent with the Kolmogorov-Ob...

  16. Unification of field theory and maximum entropy methods for learning probability densities.

    Kinney, Justin B


    The need to estimate smooth probability distributions (a.k.a. probability densities) from finite sampled data is ubiquitous in science. Many approaches to this problem have been described, but none is yet regarded as providing a definitive solution. Maximum entropy estimation and Bayesian field theory are two such approaches. Both have origins in statistical physics, but the relationship between them has remained unclear. Here I unify these two methods by showing that every maximum entropy density estimate can be recovered in the infinite smoothness limit of an appropriate Bayesian field theory. I also show that Bayesian field theory estimation can be performed without imposing any boundary conditions on candidate densities, and that the infinite smoothness limit of these theories recovers the most common types of maximum entropy estimates. Bayesian field theory thus provides a natural test of the maximum entropy null hypothesis and, furthermore, returns an alternative (lower entropy) density estimate when the maximum entropy hypothesis is falsified. The computations necessary for this approach can be performed rapidly for one-dimensional data, and software for doing this is provided.

  17. Sorting cells by their density

    Norouzi, Nazila; Bhakta, Heran C.


    Sorting cells by their type is an important capability in biological research and medical diagnostics. However, most cell sorting techniques rely on labels or tags, which may have limited availability and specificity. Sorting different cell types by their different physical properties is an attractive alternative to labels because all cells intrinsically have these physical properties. But some physical properties, like cell size, vary significantly from cell to cell within a cell type; this makes it difficult to identify and sort cells based on their sizes alone. In this work we continuously sort different cells types by their density, a physical property with much lower cell-to-cell variation within a cell type (and therefore greater potential to discriminate different cell types) than other physical properties. We accomplish this using a 3D-printed microfluidic chip containing a horizontal flowing micron-scale density gradient. As cells flow through the chip, Earth’s gravity makes each cell move vertically to the point where the cell’s density matches the surrounding fluid’s density. When the horizontal channel then splits, cells with different densities are routed to different outlets. As a proof of concept, we use our density sorter chip to sort polymer microbeads by their material (polyethylene and polystyrene) and blood cells by their type (white blood cells and red blood cells). The chip enriches the fraction of white blood cells in a blood sample from 0.1% (in whole blood) to nearly 98% (in the output of the chip), a 1000x enrichment. Any researcher with access to a 3D printer can easily replicate our density sorter chip and use it in their own research using the design files provided as online Supporting Information. Additionally, researchers can simulate the performance of a density sorter chip in their own applications using the Python-based simulation software that accompanies this work. The simplicity, resolution, and throughput of this


    Abhijit Sinha


    Full Text Available A comparative analysis on thermodynamic efficiency based on maximum power & power density conditions have been performed for a solar-driven Carnot heat engine with internal irreversibility. In this analysis, the heat transfer from the hot reservoir is to be in the radiation mode and the heat transfer to the cold reservoir is to be in the convection mode. The thermodynamic efficiency function, power & power density functions have been derived and maximization of the power functions have been performed for various design parameters. From the optimum conditions, the thermal efficiencies at maximum power and power densities have been obtained. The effects of internal irreversibility, extreme temperature ratios & specific engine size in area ratio between the hot & cold reservoirs as various design parameters on thermodynamic efficiencies have been investigated for both the conditions. The efficiencies have been compared with Curzon-Ahlborn & Carnot efficiencies respectively.The analysis showed that the efficiency at maximum power output is greater than the efficiency at maximum power density. And the efficiencies can be greater than the Curzon- Ahlborn`s efficiency only for low values of design parameters.

  19. On the rate of convergence of the maximum likelihood estimator of a k-monotone density

    WELLNER; Jon; A


    Bounds for the bracketing entropy of the classes of bounded k-monotone functions on [0,A] are obtained under both the Hellinger distance and the Lp(Q) distance,where 1 p < ∞ and Q is a probability measure on [0,A].The result is then applied to obtain the rate of convergence of the maximum likelihood estimator of a k-monotone density.

  20. On the rate of convergence of the maximum likelihood estimator of a K-monotone density

    GAO FuChang; WELLNER Jon A


    Bounds for the bracketing entropy of the classes of bounded K-monotone functions on [0, A] are obtained under both the Hellinger distance and the LP(Q) distance, where 1 ≤ p < ∞ and Q is a probability measure on [0, A]. The result is then applied to obtain the rate of convergence of the maximum likelihood estimator of a K-monotone density.

  1. 3D Global Coronal Density Structure and Associated Magnetic Field near Solar Maximum

    Kramar, Maxim; Lin, Haosheng


    Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal dynamic phenomena at all scales. We employ STEREO/COR1 data obtained near maximum of solar activity in December 2012 (Carrington rotation, CR 2131) to retrieve and analyze the three-dimensional (3D) coronal electron density in the range of heights from $1.5$ to $4\\ \\mathrm{R}_\\odot$ using a tomography method and qualitatively deduce structures of the coronal magnetic field. The 3D electron density analysis is complemented by the 3D STEREO/EUVI emissivity in 195 \\AA \\ band obtained by tomography for the same CR period. We find that the magnetic field configuration during CR 2131 has a tendency to become radially open at heliocentric distances below $\\sim 2.5 \\ \\mathrm{R}_\\odot$. We compared the reconstructed 3D coronal structures over the CR near the solar maximum to the one at deep solar minimum. Results of our 3D density reconstruction will help to constrain solar coronal field models and test the a...

  2. 3D Global Coronal Density Structure and Associated Magnetic Field near Solar Maximum

    Maxim Kramar


    Full Text Available Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal dynamic phenomena at all scales. We employ STEREO/COR1 data obtained near maximum of solar activity in December 2012 (Carrington rotation, CR 2131 to retrieve and analyze the three-dimensional (3D coronal electron density in the range of heights from $1.5$ to $4 R_odot$ using a tomography method and qualitatively deduce structures of the coronal magnetic field. The 3D electron density analysis is complemented by the 3D STEREO/EUVI emissivity in 195 AA band obtained by tomography for the same CR period. We find that the magnetic field configuration during CR 2131 has a tendency to become radially open at heliocentric distances below $sim 2.5 R_odot$. We compared the reconstructed 3D coronal structures over the CR near the solar maximum to the one at deep solar minimum. Results of our 3D density reconstruction will help to constrain solar coronal field models and test the accuracy of the magnetic field approximations for coronal modeling.

  3. 3D Global Coronal Density Structure and Associated Magnetic Field near Solar Maximum

    Kramar, Maxim; Airapetian, Vladimir; Lin, Haosheng


    Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal dynamic phenomena at all scales. We employ STEREO/COR1 data obtained near maximum of solar activity in December 2012 (Carrington rotation, CR 2131) to retrieve and analyze the three-dimensional (3D) coronal electron density in the range of heights from 1.5 to 4 R_⊙ using a tomography method and qualitatively deduce structures of the coronal magnetic field. The 3D electron density analysis is complemented by the 3D STEREO/EUVI emissivity in 195 Å band obtained by tomography for the same CR period. We find that the magnetic field configuration during CR 2131 has a tendency to become radially open at heliocentric distances below ˜ 2.5 R_⊙. We compared the reconstructed 3D coronal structures over the CR near the solar maximum to the one at deep solar minimum. Results of our 3D density reconstruction will help to constrain solar coronal field models and test the accuracy of the magnetic field approximations for coronal modeling.

  4. Spectral density analysis of time correlation functions in lattice QCD using the maximum entropy method

    Fiebig, H R


    We study various aspects of extracting spectral information from time correlation functions of lattice QCD by means of Bayesian inference with an entropic prior, the maximum entropy method (MEM). Correlator functions of a heavy-light meson-meson system serve as a repository for lattice data with diverse statistical quality. Attention is given to spectral mass density functions, inferred from the data, and their dependence on the parameters of the MEM. We propose to employ simulated annealing, or cooling, to solve the Bayesian inference problem, and discuss practical issues of the approach.

  5. Probing Ionic Liquid Aqueous Solutions Using Temperature of Maximum Density Isotope Effects

    Mohammad Tariq


    Full Text Available This work is a new development of an extensive research program that is investigating for the first time shifts in the temperature of maximum density (TMD of aqueous solutions caused by ionic liquid solutes. In the present case we have compared the shifts caused by three ionic liquid solutes with a common cation—1-ethyl-3-methylimidazolium coupled with acetate, ethylsulfate and tetracyanoborate anions—in normal and deuterated water solutions. The observed differences are discussed in terms of the nature of the corresponding anion-water interactions.

  6. Limit Distribution Theory for Maximum Likelihood Estimation of a Log-Concave Density.

    Balabdaoui, Fadoua; Rufibach, Kaspar; Wellner, Jon A


    We find limiting distributions of the nonparametric maximum likelihood estimator (MLE) of a log-concave density, i.e. a density of the form f(0) = exp varphi(0) where varphi(0) is a concave function on R. Existence, form, characterizations and uniform rates of convergence of the MLE are given by Rufibach (2006) and Dümbgen and Rufibach (2007). The characterization of the log-concave MLE in terms of distribution functions is the same (up to sign) as the characterization of the least squares estimator of a convex density on [0, infinity) as studied by Groeneboom, Jongbloed and Wellner (2001b). We use this connection to show that the limiting distributions of the MLE and its derivative are, under comparable smoothness assumptions, the same (up to sign) as in the convex density estimation problem. In particular, changing the smoothness assumptions of Groeneboom, Jongbloed and Wellner (2001b) slightly by allowing some higher derivatives to vanish at the point of interest, we find that the pointwise limiting distributions depend on the second and third derivatives at 0 of H(k), the "lower invelope" of an integrated Brownian motion process minus a drift term depending on the number of vanishing derivatives of varphi(0) = log f(0) at the point of interest. We also establish the limiting distribution of the resulting estimator of the mode M(f(0)) and establish a new local asymptotic minimax lower bound which shows the optimality of our mode estimator in terms of both rate of convergence and dependence of constants on population values.

  7. Maximum density of quantum information in a scalable CMOS implementation of the hybrid qubit architecture

    Rotta, Davide; De Michielis, Marco; Ferraro, Elena; Fanciulli, Marco; Prati, Enrico


    Scalability from single-qubit operations to multi-qubit circuits for quantum information processing requires architecture-specific implementations. Semiconductor hybrid qubit architecture is a suitable candidate to realize large-scale quantum information processing, as it combines a universal set of logic gates with fast and all-electrical manipulation of qubits. We propose an implementation of hybrid qubits, based on Si metal-oxide-semiconductor (MOS) quantum dots, compatible with the CMOS industrial technological standards. We discuss the realization of multi-qubit circuits capable of fault-tolerant computation and quantum error correction, by evaluating the time and space resources needed for their implementation. As a result, the maximum density of quantum information is extracted from a circuit including eight logical qubits encoded by the [[7, 1, 3

  8. Shifts in the temperature of maximum density (TMD) of ionic liquid aqueous solutions.

    Tariq, M; Esperança, J M S S; Soromenho, M R C; Rebelo, L P N; Lopes, J N Canongia


    This work investigates for the first time shifts in the temperature of maximum density (TMD) of water caused by ionic liquid solutes. A vast amount of high-precision volumetric data--more than 6000 equilibrated (static) high-precision density determination corresponding to ∼90 distinct ionic liquid aqueous solutions of 28 different types of ionic liquid--allowed us to analyze the TMD shifts for different homologous series or similar sets of ionic solutes and explain the overall effects in terms of hydrophobic, electrostatic and hydrogen-bonding contributions. The differences between the observed TMD shifts in the -2 temperatures are discussed taking into account the different types of possible solute-water interactions that can modify the structure of the aqueous phase. The results also reveal different insights concerning the nature of the ions that constitute typical ionic liquids and are consistent with previous results that established hydrophobic and hydrophilic scales for ionic liquid ions based on their specific interactions with water and other probe molecules.

  9. An empirical method for estimating probability density functions of gridded daily minimum and maximum temperature

    Lussana, C.


    The presented work focuses on the investigation of gridded daily minimum (TN) and maximum (TX) temperature probability density functions (PDFs) with the intent of both characterising a region and detecting extreme values. The empirical PDFs estimation procedure has been realised using the most recent years of gridded temperature analysis fields available at ARPA Lombardia, in Northern Italy. The spatial interpolation is based on an implementation of Optimal Interpolation using observations from a dense surface network of automated weather stations. An effort has been made to identify both the time period and the spatial areas with a stable data density otherwise the elaboration could be influenced by the unsettled station distribution. The PDF used in this study is based on the Gaussian distribution, nevertheless it is designed to have an asymmetrical (skewed) shape in order to enable distinction between warming and cooling events. Once properly defined the occurrence of extreme events, it is possible to straightforwardly deliver to the users the information on a local-scale in a concise way, such as: TX extremely cold/hot or TN extremely cold/hot.

  10. Observation of a shape-dependent density maximum in random prackigns and glasses of colloidal silica ellipsoids

    Sacanna, S.; Rossi, L.; Wouterse, A.; Philipse, A.P.


    We have measured the random packing density of monodisperse colloidal silica ellipsoids with a well-defined shape, gradually deviating from a sphere shape up to prolates with aspect ratios of about 5, to find for a colloidal system the first experimental observation for the density maximum (at an as

  11. Flow distribution and maximum current density studies in redox flow batteries with a single passage of the serpentine flow channel

    Ke, Xinyou; Alexander, J. Iwan D.; Prahl, Joseph M.; Savinell, Robert F.


    Flow batteries show promise for very large-scale stationary energy storage such as needed for the grid and renewable energy implementation. In recent years, researchers and developers of redox flow batteries (RFBs) have found that electrode and flow field designs of PEM fuel cell (PEMFC) technology can increase the power density and consequently push down the cost of flow battery stacks. In this paper we present a macroscopic model of a typical PEMFC-like RFB electrode-flow field design. The model is a layered system comprised of a single passage of a serpentine flow channel and a parallel underlying porous electrode (or porous layer). The effects of the inlet volumetric flow rate, permeability of the porous layer, thickness of the porous layer and thickness of the flow channel on the flow penetration into the porous layer are investigated. The maximum current density corresponding to stoichiometry is estimated to be 377 mA cm-2 and 724 mA cm-2, which compares favorably with experiments of ∼400 mA cm-2 and ∼750 mA cm-2, for a single layer and three layers of the carbon fiber paper, respectively.

  12. Electron densities by the maximum entropy method (MEM) for various types of prior densities: a case study on three amino acids and a tripeptide.

    Prathapa, Siriyara Jagannatha; Mondal, Swastik; van Smaalen, Sander


    Dynamic model densities according to Mondal et al. [(2012), Acta Cryst. A68, 568-581] are presented for independent atom models (IAM), IAMs after high-order refinements (IAM-HO), invariom (INV) models and multipole (MP) models of α-glycine, DL-serine, L-alanine and Ala-Tyr-Ala at T ≃ 20 K. Each dynamic model density is used as prior in the calculation of electron density according to the maximum entropy method (MEM). We show that at the bond-critical points (BCPs) of covalent C-C and C-N bonds the IAM-HO and INV priors produce reliable MEM density maps, including reliable values for the density and its Laplacian. The agreement between these MEM density maps and dynamic MP density maps is less good for polar C-O bonds, which is explained by the large spread of values of topological descriptors of C-O bonds in static MP densities. The density and Laplacian at BCPs of hydrogen bonds have similar values in MEM density maps obtained with all four kinds of prior densities. This feature is related to the smaller spatial variation of the densities in these regions, as expressed by small magnitudes of the Laplacians and the densities. It is concluded that the use of the IAM-HO prior instead of the IAM prior leads to improved MEM density maps. This observation shows interesting parallels to MP refinements, where the use of the IAM-HO as an initial model is the accepted procedure for solving MP parameters. A deconvolution of thermal motion and static density that is better than the deconvolution of the IAM appears to be necessary in order to arrive at the best MP models as well as at the best MEM densities.

  13. Modeling the impact of the indigenous microbial population on the maximum population density of Salmonella on alfalfa

    Rijgersberg, H.; Nierop Groot, M.N.; Tromp, S.O.; Franz, E.


    Within a microbial risk assessment framework, modeling the maximum population density (MPD) of a pathogenic microorganism is important but often not considered. This paper describes a model predicting the MPD of Salmonella on alfalfa as a function of the initial contamination level, the total count

  14. Charge density study with the Maximum Entropy Method on model data of silicon. A search for non-nuclear attractors

    Vries, de R.Y.; Briels, W.J.; Feil, D.; Velde, te G.; Baerends, E.J.


    1990 Sakata and Sato applied the maximum entropy method (MEM) to a set of structure factors measured earlier by Saka and Kato with the Pendellösung method. They found the presence of non-nuclear attractors, i.e., maxima in the density between two bonded atoms. We applied the MEM to a limited set of

  15. Application of maximum likelihood to direct methods: the probability density function of the triple-phase sums. XI.

    Rius, Jordi


    The maximum-likelihood method is applied to direct methods to derive a more general probability density function of the triple-phase sums which is capable of predicting negative values. This study also proves that maximization of the origin-free modulus sum function S yields, within the limitations imposed by the assumed approximations, the maximum-likelihood estimates of the phases. It thus represents the formal theoretical justification of the S function that was initially derived from Patterson-function arguments [Rius (1993). Acta Cryst. A49, 406-409].

  16. Cooling of Water in a Flask: Convection Currents in a Fluid with a Density Maximum

    Velasco, S.; White, J. A.; Roman, F. L.


    The effect of density inversion on the convective flow of water in a spherical glass flask cooled with the help of an ice-water bath is shown. The experiment was carried out by temperature measurements (cooling curves) taken at three different heights along the vertical diameter of the flask. Flows inside the flask are visualized by seeding the…

  17. Cooling of Water in a Flask: Convection Currents in a Fluid with a Density Maximum

    Velasco, S.; White, J. A.; Roman, F. L.


    The effect of density inversion on the convective flow of water in a spherical glass flask cooled with the help of an ice-water bath is shown. The experiment was carried out by temperature measurements (cooling curves) taken at three different heights along the vertical diameter of the flask. Flows inside the flask are visualized by seeding the…

  18. Normal corneal endothelial cell density in Nigerians

    Ewete T


    Full Text Available Temitope Ewete,1 Efeoghene Uchenna Ani,2 Adegboyega Sunday Alabi1 1MeCure Eye Center, Lagos, 2Department of Ophthalmology, University of Port Harcourt, Port Harcourt, Nigeria Aim: The aim of the study was to describe the corneal endothelial cell density of adults at the MeCure Eye Center and to determine the relationship between age, sex, and corneal endothelial cell density. Methods: This study was a retrospective study looking at those records of individuals who had undergone specular microscopy or corneal endothelial cell count measurement at the MeCure Eye Center. Results: The endothelial cell characteristics of 359 healthy eyes of 201 volunteers were studied. The mean corneal endothelial cell density (MCD was 2,610.26±371.87 cells/mm2 (range, 1,484–3,571 cells/mm2. The MCD decreased from 2,860.70 cells/mm2 in the 20–30-year age group to 2,493.06 cells/mm2 in the >70-year age group, and there was a statistically significant relationship between age and MCD with a P-value of <0.001. There was no statistically significant correlation between sex and corneal endothelial cell density (P=0.45. Conclusion: This study shows that endothelial cell density in Nigerian eyes is less than that reported in the Japanese, American, and Chinese eyes, and is comparable to that seen in Indian and Malaysian eyes. Keywords: corneal, endothelial cell density, Nigerian

  19. Ru/Al Multilayers Integrate Maximum Energy Density and Ductility for Reactive Materials

    K. Woll; Bergamaschi, A; Avchachov, K.; Djurabekova, F.; Gier, S.; Pauly, C.; Leibenguth, P.; Wagner, C; Nordlund, K.; Mücklich, F


    Established and already commercialized energetic materials, such as those based on Ni/Al for joining, lack the adequate combination of high energy density and ductile reaction products. To join components, this combination is required for mechanically reliable bonds. In addition to the improvement of existing technologies, expansion into new fields of application can also be anticipated which triggers the search for improved materials. Here, we present a comprehensive characterization of the ...

  20. Ru/Al Multilayers Integrate Maximum Energy Density and Ductility for Reactive Materials.

    Woll, K; Bergamaschi, A; Avchachov, K; Djurabekova, F; Gier, S; Pauly, C; Leibenguth, P; Wagner, C; Nordlund, K; Mücklich, F


    Established and already commercialized energetic materials, such as those based on Ni/Al for joining, lack the adequate combination of high energy density and ductile reaction products. To join components, this combination is required for mechanically reliable bonds. In addition to the improvement of existing technologies, expansion into new fields of application can also be anticipated which triggers the search for improved materials. Here, we present a comprehensive characterization of the key parameters that enables us to classify the Ru/Al system as new reactive material among other energetic systems. We finally found that Ru/Al exhibits the unusual integration of high energy density and ductility. For example, we measured reaction front velocities up to 10.9 (± 0.33) ms(-1) and peak reaction temperatures of about 2000 °C indicating the elevated energy density. To our knowledge, such high temperatures have never been reported in experiments for metallic multilayers. In situ experiments show the synthesis of a single-phase B2-RuAl microstructure ensuring improved ductility. Molecular dynamics simulations corroborate the transformation behavior to RuAl. This study fundamentally characterizes a Ru/Al system and demonstrates its enhanced properties fulfilling the identification requirements of a novel nanoscaled energetic material.

  1. Maximum-Likelihood Sequence Detector for Dynamic Mode High Density Probe Storage

    Kumar, Naveen; Ramamoorthy, Aditya; Salapaka, Murti


    There is an ever increasing need for storing data in smaller and smaller form factors driven by the ubiquitous use and increased demands of consumer electronics. A new approach of achieving a few Tb per in2 areal densities, utilizes a cantilever probe with a sharp tip that can be used to deform and assess the topography of the material. The information may be encoded by means of topographic profiles on a polymer medium. The prevalent mode of using the cantilever probe is the static mode that is known to be harsh on the probe and the media. In this paper, the high quality factor dynamic mode operation, which is known to be less harsh on the media and the probe, is analyzed for probe based high density data storage purposes. It is demonstrated that an appropriate level of abstraction is possible that obviates the need for an involved physical model. The read operation is modeled as a communication channel which incorporates the inherent system memory due to the intersymbol interference and the cantilever state ...

  2. Minimal pesticide-primed soil inoculum density to secure maximum pesticide degradation efficiency in on-farm biopurification systems.

    Sniegowski, Kristel; Bers, Karolien; Ryckeboer, Jaak; Jaeken, Peter; Spanoghe, Pieter; Springael, Dirk


    Addition of pesticide-primed soil containing adapted pesticide degrading bacteria to the biofilter matrix of on farm biopurification systems (BPS) which treat pesticide contaminated wastewater, has been recommended, in order to ensure rapid establishment of a pesticide degrading microbial community in BPS. However, uncertainties exist about the minimal soil inoculum density needed for successful bioaugmentation of BPS. Therefore, in this study, BPS microcosm experiments were initiated with different linuron primed soil inoculum densities ranging from 0.5 to 50 vol.% and the evolution of the linuron mineralization capacity in the microcosms was monitored during feeding with linuron. Successful establishment of a linuron mineralization community in the BPS microcosms was achieved with all inoculum densities including the 0.5 vol.% density with only minor differences in the time needed to acquire maximum degradation capacity. Moreover, once established, the robustness of the linuron degrading microbial community towards expected stress situations proved to be independent of the initial inoculum density. This study shows that pesticide-primed soil inoculum densities as low as 0.5 vol.% can be used for bioaugmentation of a BPS matrix and further supports the use of BPS for treatment of pesticide-contaminated wastewater at farmyards.

  3. Testing for the maximum cell probabilities in multinomial distributions

    XIONG Shifeng; LI Guoying


    This paper investigates one-sided hypotheses testing for p[1], the largest cell probability of multinomial distribution. A small sample test of Ethier (1982) is extended to the general cases. Based on an estimator of p[1], a kind of large sample tests is proposed. The asymptotic power of the above tests under local alternatives is derived. An example is presented at the end of this paper.

  4. Electron density distribution and bonding in ZnSe and PbSe using maximum entropy method (MEM)

    K S Syed Ali; R Saravanan; S Israel; R K Rajaram


    The study of electronic structure of materials and bonding is an important part of material characterization. The maximum entropy method (MEM) is a powerful tool for deriving accurate electron density distribution in crystalline materials using experimental data. In this paper, the attention is focused on producing electron density distribution of ZnSe and PbSe using JCPDS X-ray powder diffraction data. The covalent/ionic nature of the bonding and the interaction between the atoms are clearly revealed by the MEM maps. The mid bond electron densities between atoms in these systems are found to be 0.544 e/Å3 and 0.261 e/Å3, respectively for ZnSe and PbSe. The bonding in these two systems has been studied using two-dimensional MEM electron density maps on the (100) and (110) planes, and the one-dimensional electron density profiles along [100], [110] and [111] directions. The thermal parameters of the individual atoms have also been reported in this work. The algorithm of the MEM procedure has been presented.

  5. Gas surface density, star formation rate surface density, and the maximum mass of young star clusters in a disk galaxy. I. The flocculent galaxy M33

    Gonzalez-Lopezlira, Rosa A; Kroupa, Pavel


    We analyze the relationship between maximum cluster mass, M_max, and surface densities of total gas (Sigma_gas), molecular gas (Sigma_H2) and star formation rate (Sigma_SFR) in the flocculent galaxy M33, using published gas data and a catalog of more than 600 young star clusters in its disk. By comparing the radial distributions of gas and most massive cluster masses, we find that M_max is proportional to Sigma_gas^4.7, M_max is proportional Sigma_H2^1.3, and M_max is proportional to Sigma_SFR^1.0. We rule out that these correlations result from the size of sample; hence, the change of the maximum cluster mass must be due to physical causes.

  6. Deriving the electron-phonon spectral density of MgB2 from optical data, using maximum entropy techniques.

    Hwang, J; Carbotte, J P


    We use maximum entropy techniques to extract an electron-phonon density from optical data for the normal state at T = 45 K of MgB2. Limiting the analysis to a range of phonon energies below 110 meV, which is sufficient for capturing all phonon structures, we find a spectral function that is in good agreement with that calculated for the quasi-two-dimensional σ-band. Extending the analysis to higher energies, up to 160 meV, we find no evidence for any additional contributions to the fluctuation spectrum, but find that the data can only be understood if the density of states is taken to decrease with increasing energy.

  7. Cell density monitoring and control of microencapsulated CHO cell cultures

    Cole, Harriet Emma


    Though mammalian cells play a key role in the manufacturing of recombinant glycosylated proteins, cell cultures and productivity are limited by the lack of suitable systems to enable stable perfusion culture. Microencapsulation, or entrapping cells within a semi-permeable membrane, offers the potential to generate high cell density cultures and improve the productivity by mimicking the cells natural environment. However, the cells being secluded by the microcapsules membrane are difficult to ...

  8. Electron density distribution in Si and Ge using multipole, maximum entropy method and pair distribution function analysis

    R Saravanan; K S Syed Ali; S Israel


    The local, average and electronic structure of the semiconducting materials Si and Ge has been studied using multipole, maximum entropy method (MEM) and pair distribution function (PDF) analyses, using X-ray powder data. The covalent nature of bonding and the interaction between the atoms are clearly revealed by the two-dimensional MEM maps plotted on (1 0 0) and (1 1 0) planes and one-dimensional density along [1 0 0], [1 1 0] and [1 1 1] directions. The mid-bond electron densities between the atoms are 0.554 e/Å3 and 0.187 e/Å3 for Si and Ge respectively. In this work, the local structural information has also been obtained by analyzing the atomic pair distribution function. An attempt has been made in the present work to utilize the X-ray powder data sets to refine the structure and electron density distribution using the currently available versatile methods, MEM, multipole analysis and determination of pair distribution function for these two systems.

  9. High power density carbonate fuel cell

    Yuh, C.; Johnsen, R.; Doyon, J.; Allen, J. [Energy Research Corp., Danbury, CT (United States)


    Carbonate fuel cell is a highly efficient and environmentally clean source of power generation. Many organizations worldwide are actively pursuing the development of the technology. Field demonstration of multi-MW size power plant has been initiated in 1996, a step toward commercialization before the turn of the century, Energy Research Corporation (ERC) is planning to introduce a 2.85MW commercial fuel cell power plant with an efficiency of 58%, which is quite attractive for distributed power generation. However, to further expand competitive edge over alternative systems and to achieve wider market penetration, ERC is exploring advanced carbonate fuel cells having significantly higher power densities. A more compact power plant would also stimulate interest in new markets such as ships and submarines where space limitations exist. The activities focused on reducing cell polarization and internal resistance as well as on advanced thin cell components.

  10. Nanostructured thin solid oxide fuel cells with high power density.

    Ignatiev, Alex; Chen, Xin; Wu, Naijuan; Lu, Zigui; Smith, Laverne


    Nanostructured thin film solid oxide fuel cells (SOFC) have been developed for reduced temperature operation, with high power density, and to be self reforming. A thin film electrolyte (1-2 microm thickness), e.g., yttria-stabilized zirconia (YSZ), is deposited on a nickel foil substrate. The electrolyte thin film is polycrystalline when deposited on a polycrystalline nickel foil substrate, and is (100) textured when deposited on an atomically textured nickel foil substrate. The Ni foil substrate is then converted into a porous SOFC anode by photolithographic patterning and etching to develop porosity. A composite La(0.5)Sr(0.5)CoO(3) cathode is then deposited on the thin film electrolyte. The resultant thin film hetero structure fuel cells have operated at a significantly reduced temperature: as low as 470 degrees C, with a maximum power density of 140 mW cm(-2) at 575 degrees C, and an efficiency of >50%. This drastic reduction in operating temperature for an SOFC now also allows for the use of hydrocarbon fuels without the need for a separate reformer as the nickel anode effectively dissociates hydrocarbons within this temperature range. These nanostructured fuel cells show excellent potential for high power density, small volume, high efficiency fuel cells for power generation applications.


    Gonzalez-Lopezlira, Rosa A. [On sabbatical leave from the Centro de Radioastronomia y Astrofisica, UNAM, Campus Morelia, Michoacan, C.P. 58089, Mexico. (Mexico); Pflamm-Altenburg, Jan; Kroupa, Pavel, E-mail: [Argelander Institut fuer Astronomie, Universitaet Bonn, Auf dem Huegel 71, D-53121 Bonn (Germany)


    We analyze the relationship between maximum cluster mass and surface densities of total gas ({Sigma}{sub gas}), molecular gas ({Sigma}{sub H{sub 2}}), neutral gas ({Sigma}{sub H{sub I}}), and star formation rate ({Sigma}{sub SFR}) in the grand-design galaxy M51, using published gas data and a catalog of masses, ages, and reddenings of more than 1800 star clusters in its disk, of which 223 are above the cluster mass distribution function completeness limit. By comparing the two-dimensional distribution of cluster masses and gas surface densities, we find for clusters older than 25 Myr that M{sub 3rd}{proportional_to}{Sigma}{sub H{sub I}{sup 0.4{+-}0.2}}, whereM{sub 3rd} is the median of the five most massive clusters. There is no correlation with{Sigma}{sub gas},{Sigma}{sub H2}, or{Sigma}{sub SFR}. For clusters younger than 10 Myr, M{sub 3rd}{proportional_to}{Sigma}{sub H{sub I}{sup 0.6{+-}0.1}} and M{sub 3rd}{proportional_to}{Sigma}{sub gas}{sup 0.5{+-}0.2}; there is no correlation with either {Sigma}{sub H{sub 2}} or{Sigma}{sub SFR}. The results could hardly be more different from those found for clusters younger than 25 Myr in M33. For the flocculent galaxy M33, there is no correlation between maximum cluster mass and neutral gas, but we have determined M{sub 3rd}{proportional_to}{Sigma}{sub gas}{sup 3.8{+-}0.3}, M{sub 3rd}{proportional_to}{Sigma}{sub H{sub 2}{sup 1.2{+-}0.1}}, and M{sub 3rd}{proportional_to}{Sigma}{sub SFR}{sup 0.9{+-}0.1}. For the older sample in M51, the lack of tight correlations is probably due to the combination of strong azimuthal variations in the surface densities of gas and star formation rate, and the cluster ages. These two facts mean that neither the azimuthal average of the surface densities at a given radius nor the surface densities at the present-day location of a stellar cluster represent the true surface densities at the place and time of cluster formation. In the case of the younger sample, even if the clusters have not yet

  12. Gas surface density, star formation rate surface density, and the maximum mass of young star clusters in a disk galaxy. II. The grand-design galaxy M51

    Gonzalez-Lopezlira, Rosa A; Kroupa, Pavel


    We analyze the relationship between maximum cluster mass, and surface densities of total gas (Sigma_gas), molecular gas (Sigma_H_2), neutral gas (Sigma_HI) and star formation rate (Sigma_SFR) in the grand design galaxy M51, using published gas data and a catalog of masses, ages, and reddenings of more than 1800 star clusters in its disk, of which 223 are above the cluster mass distribution function completeness limit. We find for clusters older than 25 Myr that M_3rd, the median of the 5 most massive clusters, is proportional to Sigma_HI^0.4. There is no correlation with Sigma_gas, Sigma_H2, or Sigma_SFR. For clusters younger than 10 Myr, M_3rd is proportional to Sigma_HI^0.6, M_3rd is proportional to Sigma_gas^0.5; there is no correlation with either Sigma_H_2 or Sigma_SFR. The results could hardly be more different than those found for clusters younger than 25 Myr in M33. For the flocculent galaxy M33, there is no correlation between maximum cluster mass and neutral gas, but M_3rd is proportional to Sigma_g...

  13. High Energy Density aluminum/oxygen cell

    Rudd, E. J.; Gibbons, D. W.

    An alternative to a secondary battery as the power source for vehicle propulsion is a fuel cell, an example of which is the metal/air cell using metals such as aluminum, zinc, or iron. Aluminum is a particularly attractive candidate, with high energy and power densities, environmentally acceptable and having a large, established industrial base for production and distribution. An aluminum/oxygen system is currently under development for a prototype unmanned, undersea vehicle (UUV) for the US navy and recent work has focussed upon low corrosion aluminum alloys, and an electrolyte management system for processing the by-products of the energy-producing reactions. This paper summarizes the progress made in both areas. Anode materials capable of providing high utilization factors over current densities ranging from 5 to 150 mA/cm 2 have been identified, such materials being essential to realize mission life for the UUV. With respect to the electrolyte management system, a filter/precipitator unit has been successfully operated for over 250 h in a large scale, half-cell system.

  14. Applying the maximum information principle to cell transmission model of tra-ffic flow

    刘喜敏; 卢守峰


    This paper integrates the maximum information principle with the Cell Transmission Model (CTM) to formulate the velo-city distribution evolution of vehicle traffic flow. The proposed discrete traffic kinetic model uses the cell transmission model to cal-culate the macroscopic variables of the vehicle transmission, and the maximum information principle to examine the velocity distri-bution in each cell. The velocity distribution based on maximum information principle is solved by the Lagrange multiplier method. The advantage of the proposed model is that it can simultaneously calculate the hydrodynamic variables and velocity distribution at the cell level. An example shows how the proposed model works. The proposed model is a hybrid traffic simulation model, which can be used to understand the self-organization phenomena in traffic flows and predict the traffic evolution.

  15. Effect of monocular deprivation on rabbit neural retinal cell densities

    Philip Maseghe Mwachaka


    Conclusion: In this rabbit model, monocular deprivation resulted in activity-dependent changes in cell densities of the neural retina in favour of the non-deprived eye along with reduced cell densities in the deprived eye.

  16. Cell-density dependent effects of low-dose ionizing radiation on E. coli cells.

    Alipov, E D; Shcheglov, V S; Sarimov, R M; Belyaev, I Ya


    The changes in genome conformational state (GCS) induced by low-dose ionizing radiation in E. coli cells were measured by the method of anomalous viscosity time dependence (AVTD) in cellular lysates. Effects of X-rays at doses 0.1 cGy--1 Gy depended on post-irradiation time. Significant relaxation of DNA loops followed by a decrease in AVTD. The time of maximum relaxation was between 5-80 min depending on the dose of irradiation. U-shaped dose response was observed with increase of AVTD in the range of 0.1-4 Gy and decrease in AVTD at higher doses. No such increase in AVTD was seen upon irradiation of cells at the beginning of cell lysis while the AVTD decrease was the same. Significant differences in the effects of X-rays and gamma-rays at the same doses were observed suggesting a strong dependence of low-dose effects on LET. Effects of 0.01 cGy gamma-rays were studied at different cell densities during irradiation. We show that the radiation-induced changes in GCS lasted longer at higher cell density as compared to lower cell density. Only small amount of cells were hit at this dose and the data suggest cell-to-cell communication in response to low-dose ionizing radiation. This prolonged effect was also observed when cells were irradiated at high cell density and diluted to low cell density immediately after irradiation. These data suggest that cell-to-cell communication occur during irradiation or within 3 min post-irradiation. The cell-density dependent response to low-dose ionizing radiation was compared with previously reported data on exposure of E. coli cells to electromagnetic fields of extremely low frequency and extremely high frequency (millimeter waves). The body of our data show that cells can communicate in response to electromagnetic fields and ionizing radiation, presumably by reemission of secondary photons in infrared-submillimeter frequency range.

  17. Influence of epoxy resin as encapsulation material of silicon photovoltaic cells on maximum current

    Acevedo-Gómez David


    Full Text Available This work presents an analysis about how the performance of silicon photovoltaic cells is influenced by the use of epoxy resin as encapsulation material with flat roughness. The effect of encapsulation on current at maximum power of mono-crystalline cell was tested indoor in a solar simulator bench at 1000 w/m² and AM1.5G. The results show that implementation of flat roughness layer onto cell surface reduces the maximum current inducing on average 2.7% less power with respect to a cell before any encapsulation. The losses of power and, in consequence, the less production of energy are explained by resin light absorption, reflection and partially neutralization of non-reflective coating.

  18. Procedure for determining maximum sustainable power generated by microbial fuel cells.

    Menicucci, Joseph; Beyenal, Haluk; Marsili, Enrico; Veluchamy, Raajaraajan Angathevar; Demir, Goksel; Lewandowski, Zbigniew


    Power generated by microbial fuel cells is computed as a product of current passing through an external resistor and voltage drop across this resistor. If the applied resistance is very low, then high instantaneous power generated by the cell is measured, which is not sustainable; the cell cannot deliver that much power for long periods of time. Since using small electrical resistors leads to erroneous assessment of the capabilities of microbial fuel cells, a question arises: what resistor should be used in such measurements? To address this question, we have defined the sustainable power as the steady state of power delivery by a microbial fuel cell under a given set of conditions and the maximum sustainable power as the highest sustainable power that a microbial fuel cell can deliver under a given set of conditions. Selecting the external resistance that is associated with the maximum sustainable power in a microbial fuel cell (MFC) is difficult because the operator has limited influence on the main factors that control power generation: the rate of charge transfer at the current-limiting electrode and the potential established across the fuel cell. The internal electrical resistance of microbial fuel cells varies, and it depends on the operational conditions of the fuel cell. We have designed an empirical procedure to predict the maximum sustainable power that can be generated by a microbial fuel cell operated under a given set of conditions. Following the procedure, we change the external resistors incrementally, in steps of 500 omega every 10, 60, or 180 s and measure the anode potential, the cathode potential, and the cell current. Power generated in the microbial fuel cell that we were using was limited by the anodic current. The anodic potential was used to determine the condition where the maximum sustainable power is obtained. The procedure is simple, microbial fuel cells can be characterized within an hour, and the results of the measurements can serve

  19. Mast cell density in cardio-esophageal mucosa.

    Mahjoub, Fatemeh E; Asefi, Hoda; Farahmand, Fatemeh; Pourpak, Zahra; Amini, Zahra


    Mast cells are related to certain gastrointestinal complaints. Mast cell density has not been studied in cardio-esophageal region to the best of our knowledge. In this study we wanted to obtain an estimate of mast cell density in this region and compare it with mast cell density in antrum. From April 2007 till March 2010, we chose children (mast cell density in the cardiac mucosa was 33.41 ± 32.75 in 0.25 mm2 (range: 0-155), which was two times of that in antral mucosa. We found a significant but weak positive correlation at the 0.05 level between mast cell density of cardiac mucosa and the antrum. Higher mast cell counts were seen in cardiac mucosa in this study. Significant positive correlation between mast cell density of cardiac mucosa and the antrum could hint to a single underlying etiology for the inflammatory process in gastro- esophageal junction and gastric mucosa.

  20. The Indigo Molecule Revisited Again: Assessment of the Minnesota Family of Density Functionals for the Prediction of Its Maximum Absorption Wavelengths in Various Solvents

    Francisco Cervantes-Navarro


    Full Text Available The Minnesota family of density functionals (M05, M05-2X, M06, M06L, M06-2X, and M06-HF were evaluated for the calculation of the UV-Vis spectra of the indigo molecule in solvents of different polarities using time-dependent density functional theory (TD-DFT and the polarized continuum model (PCM. The maximum absorption wavelengths predicted for each functional were compared with the known experimental results.

  1. Extension Sliding Mode Controller for Maximum Power Point Tracking of Hydrogen Fuel Cells

    Meng-Hui Wang


    Full Text Available Fuel cells (FCs are characterized by low pollution, low noise, and high efficiency. However, the voltage-current response of an FC is nonlinear, with the result that there exists just one operating point which maximizes the output power given a particular set of operating conditions. Accordingly, the present study proposes a maximum power point tracking (MPPT control scheme based on extension theory to stabilize the output of an FC at the point of maximum power. The simulation results confirm the ability of the controller to stabilize the output power at the maximum power point despite sudden changes in the temperature, hydrogen pressure, and membrane water content. Moreover, the transient response time of the proposed controller is shown to be faster than that of existing sliding mode (SM and extremum seeking (ES controllers.

  2. Robust cell tracking in epithelial tissues through identification of maximum common subgraphs.

    Kursawe, Jochen; Bardenet, Rémi; Zartman, Jeremiah J; Baker, Ruth E; Fletcher, Alexander G


    Tracking of cells in live-imaging microscopy videos of epithelial sheets is a powerful tool for investigating fundamental processes in embryonic development. Characterizing cell growth, proliferation, intercalation and apoptosis in epithelia helps us to understand how morphogenetic processes such as tissue invagination and extension are locally regulated and controlled. Accurate cell tracking requires correctly resolving cells entering or leaving the field of view between frames, cell neighbour exchanges, cell removals and cell divisions. However, current tracking methods for epithelial sheets are not robust to large morphogenetic deformations and require significant manual interventions. Here, we present a novel algorithm for epithelial cell tracking, exploiting the graph-theoretic concept of a 'maximum common subgraph' to track cells between frames of a video. Our algorithm does not require the adjustment of tissue-specific parameters, and scales in sub-quadratic time with tissue size. It does not rely on precise positional information, permitting large cell movements between frames and enabling tracking in datasets acquired at low temporal resolution due to experimental constraints such as phototoxicity. To demonstrate the method, we perform tracking on the Drosophila embryonic epidermis and compare cell-cell rearrangements to previous studies in other tissues. Our implementation is open source and generally applicable to epithelial tissues.

  3. Detailed analysis of an endoreversible fuel cell : Maximum power and optimal operating temperature determination

    Vaudrey, A; Lanzetta, F; Glises, R


    Producing useful electrical work in consuming chemical energy, the fuel cell have to reject heat to its surrounding. However, as it occurs for any other type of engine, this thermal energy cannot be exchanged in an isothermal way in finite time through finite areas. As it was already done for various types of systems, we study the fuel cell within the finite time thermodynamics framework and define an endoreversible fuel cell. Considering different types of heat transfer laws, we obtain an optimal value of the operating temperature, corresponding to a maximum produced power. This analysis is a first step of a thermodynamical approach of design of thermal management devices, taking into account performances of the whole system.

  4. A comparison of conventional maximum intensity projection with a new depth-specific topographic mapping technique in the CT analysis of proximal tibial subchondral bone density

    Johnston, James D. [University of Saskatchewan, Department of Mechanical Engineering, Saskatoon, SK (Canada); University of British Columbia, Department of Mechanical Engineering, Vancouver, BC (Canada); Kontulainen, Saija A. [University of Saskatchewan, College of Kinesiology, Saskatoon, SK (Canada); Masri, Bassam A.; Wilson, David R. [University of British Columbia, Department of Orthopaedics, Vancouver, BC (Canada)


    The objective was to identify subchondral bone density differences between normal and osteoarthritic (OA) proximal tibiae using computed tomography osteoabsorptiometry (CT-OAM) and computed tomography topographic mapping of subchondral density (CT-TOMASD). Sixteen intact cadaver knees from ten donors (8 male:2 female; mean age:77.8, SD:7.4 years) were categorized as normal (n = 10) or OA (n = 6) based upon CT reconstructions. CT-OAM assessed maximum subchondral bone mineral density (BMD). CT-TOMASD assessed average subchondral BMD across three layers (0-2.5, 2.5-5 and 5-10 mm) measured in relation to depth from the subchondral surface. Regional analyses of CT-OAM and CT-TOMASD included: medial BMD, lateral BMD, and average BMD of a 10-mm diameter area that searched each medial and lateral plateau for the highest ''focal'' density present within each knee. Compared with normal knees, both CT-OAM and CT-TOMASD demonstrated an average of 17% greater whole medial compartment density in OA knees (p < 0.016). CT-OAM did not distinguish focal density differences between OA and normal knees (p > 0.05). CT-TOMASD focal region analyses revealed an average of 24% greater density in the 0- to 2.5-mm layer (p = 0.003) and 36% greater density in the 2.5- to 5-mm layer (p = 0.034) in OA knees. Both CT-OAM and TOMASD identified higher medial compartment density in OA tibiae compared with normal tibiae. In addition, CT-TOMASD indicated greater focal density differences between normal and OA knees with increased depth from the subchondral surface. Depth-specific density analyses may help identify and quantify small changes in subchondral BMD associated with OA disease onset and progression. (orig.)

  5. Intelligent energy harvesting scheme for microbial fuel cells: Maximum power point tracking and voltage overshoot avoidance

    Alaraj, Muhannad; Radenkovic, Miloje; Park, Jae-Do


    Microbial fuel cells (MFCs) are renewable and sustainable energy sources that can be used for various applications. The MFC output power depends on its biochemical conditions as well as the terminal operating points in terms of output voltage and current. There exists one operating point that gives the maximum possible power from the MFC, maximum power point (MPP), for a given operating condition. However, this MPP may vary and needs to be tracked in order to maintain the maximum power extraction from the MFC. Furthermore, MFC reactors often develop voltage overshoots that cause drastic drops in the terminal voltage, current, and the output power. When the voltage overshoot happens, an additional control measure is necessary as conventional MPPT algorithms will fail because of the change in the voltage-current relationship. In this paper, the extremum seeking (ES) algorithm was used to track the varying MPP and a voltage overshoot avoidance (VOA) algorithm is developed to manage the voltage overshoot conditions. The proposed ES-MPPT with VOA algorithm was able to extract 197.2 mJ during 10-min operation avoiding voltage overshoot, while the ES MPPT-only scheme stopped harvesting after only 18.75 mJ because of the voltage overshoot happened at 0.4 min.

  6. Novel negative mass density resonant metamaterial unit cell

    Cselyuszka, Norbert, E-mail:; Sečujski, Milan, E-mail:; Crnojević-Bengin, Vesna, E-mail:


    In this paper a novel resonant unit cell of one-dimensional acoustic metamaterials is presented, which exhibits negative effective mass density. We theoretically analyze the unit cell and develop a closed analytical formula for its effective mass density. Then we proceed to demonstrate left-handed propagation of acoustic waves using the proposed unit cell. Finally, we present its dual-band version, capable of operating at two independent frequencies. - Highlights: • A novel acoustic metamaterial unit cell provides Lorentz-type resonant effective mass density. • Analytical formula for effective mass density is derived. • Acoustic bandstop medium and left-handed metamaterial based on the novel unit cell are presented. • Modified version of the unit cell, operating at two independent frequencies, is proposed.

  7. Matching of Silicon Thin-Film Tandem Solar Cells for Maximum Power Output

    C. Ulbrich


    Full Text Available We present a meaningful characterization method for tandem solar cells. The experimental method allows for optimizing the output power instead of the current. Furthermore, it enables the extraction of the approximate AM1.5g efficiency when working with noncalibrated spectra. Current matching of tandem solar cells under short-circuit condition maximizes the output current but is disadvantageous for the overall fill factor and as a consequence does not imply an optimization of the output power of the device. We apply the matching condition to the maximum power output; that is, a stack of solar cells is power matched if the power output of each subcell is maximal at equal subcell currents. The new measurement procedure uses additional light-emitting diodes as bias light in the JV characterization of tandem solar cells. Using a characterized reference tandem solar cell, such as a hydrogenated amorphous/microcrystalline silicon tandem, it is possible to extract the AM1.5g efficiency from tandems of the same technology also under noncalibrated spectra.

  8. Maximum Inhibition of Breast Cancer/Stem Cell Growth by Concomitant Blockage of Key Receptors

    Mossa Gardaneh


    Full Text Available The blockage of cancer cell growth and division is the prime objective in clinical cancer therapy both at early stages and for inhibition of minimal residual disease and relapse. The failure of conventional therapies in treating breast cancer (BC has prompted dissection of signalling pathways involved in BC cell growth and characterisation of cellular receptors. Specific sets of membrane-bound receptors promote disarrayed self-renewal of BC stem cells and deregulated BC cell proliferation. Individual blockage of each receptor promotes only incomplete inhibition of BC cell growth and partial regression of metastasis. Such monotherapies are based on either chemotherapy or monoclonal antibodies. However, they do not provide long-lasting benefits and are further compromised by increasing resistance the cancer cells acquire against therapeutic agents, by their evasion of receptor blockage and by adoption of alternative growth routes that are induced by cross-talks between key receptors. On the other hand, dual targeting approaches, including receptor blockage combined with chemotherapy, produce prolonged overall survival but, nevertheless, complicate treatment by inducing side effects. Based on the complex nature of BC, combined targeted strategies that potentially confer maximum coverage for treatment cannot be effective without overcoming drug resistance initiated and further induced by inter-receptor communications. This implies that a comprehensive strategy based on concomitant inhibition of key receptors could provide an ultimate solution for effective treatment of aggressive types of BC. Such a strategy would likely be capable of targeting breast tumour cells and BC stem cells alike eventually forcing the cancer to regress.

  9. Weighted maximum posterior marginals for random fields using an ensemble of conditional densities from multiple Markov chain Monte Carlo simulations.

    Monaco, James Peter; Madabhushi, Anant


    The ability of classification systems to adjust their performance (sensitivity/specificity) is essential for tasks in which certain errors are more significant than others. For example, mislabeling cancerous lesions as benign is typically more detrimental than mislabeling benign lesions as cancerous. Unfortunately, methods for modifying the performance of Markov random field (MRF) based classifiers are noticeably absent from the literature, and thus most such systems restrict their performance to a single, static operating point (a paired sensitivity/specificity). To address this deficiency we present weighted maximum posterior marginals (WMPM) estimation, an extension of maximum posterior marginals (MPM) estimation. Whereas the MPM cost function penalizes each error equally, the WMPM cost function allows misclassifications associated with certain classes to be weighted more heavily than others. This creates a preference for specific classes, and consequently a means for adjusting classifier performance. Realizing WMPM estimation (like MPM estimation) requires estimates of the posterior marginal distributions. The most prevalent means for estimating these--proposed by Marroquin--utilizes a Markov chain Monte Carlo (MCMC) method. Though Marroquin's method (M-MCMC) yields estimates that are sufficiently accurate for MPM estimation, they are inadequate for WMPM. To more accurately estimate the posterior marginals we present an equally simple, but more effective extension of the MCMC method (E-MCMC). Assuming an identical number of iterations, E-MCMC as compared to M-MCMC yields estimates with higher fidelity, thereby 1) allowing a far greater number and diversity of operating points and 2) improving overall classifier performance. To illustrate the utility of WMPM and compare the efficacies of M-MCMC and E-MCMC, we integrate them into our MRF-based classification system for detecting cancerous glands in (whole-mount or quarter) histological sections of the prostate.

  10. Microvessel and mast cell densities in malignant laryngeal neoplasm

    Balica Nicolae Constantin


    Full Text Available Laryngeal neoplasm contributes to 30-40% of carcinomas of the head and neck. Mast cells are normal connective tissue residents, well represented in the respiratory tract. Experimental evidence suggests that the growth of a tumor beyond a certain size requires angiogenesis, which may also permit metastasis. The aim of this study was to evaluate the correlation between mast cell density, microvascular density, histopathological type and histological grade. Our study included 38 laryngeal carcinomas as follows: adenoid cystic carcinoma (2 cases, malignant papilloma (2 cases and squamous cell carcinoma (34 cases. The combined technique of CD 34-alcian blue safranin (ABS was used to identify microvessel and mast cell density, which was quantified by the hot spot method. A significant correlation was found between both mast cell and microvascular density, and G1/G2 histological grade (p=0.002 and p=0.004, respectively. Squamous cell carcinoma was significantly correlated with mast cell density (p=0.003, but not with microvascular density (p=0.454.

  11. Stability of high cell density brewery fermentations during serial repitching.

    Verbelen, Pieter J; Dekoninck, Tinne M L; Van Mulders, Sebastiaan E; Saerens, Sofie M G; Delvaux, Filip; Delvaux, Freddy R


    The volumetric productivity of the beer fermentation process can be increased by using a higher pitching rate (i.e. higher inoculum size). However, the decreased yeast net growth observed in these high cell density brewery fermentations can adversely affect the physiological stability throughout subsequent yeast generations. Therefore, different O(2) conditions (wort aeration and yeast preoxygenation) were applied to high cell density fermentation and eight generations of fermentations were evaluated together with conventional fermentations. Freshly propagated high cell density populations adapted faster to the fermentative conditions than normal cell density populations. Preoxygenating the yeast was essential for the yeast physiological and beer flavor compound stability of high cell density fermentations during serial repitching. In contrast, the use of non-preoxygenated yeast resulted in inadequate growth which caused (1) insufficient yield of biomass to repitch all eight generations, (2) a 10% decrease in viability, (3) a moderate increase of yeast age, (4) and a dramatic increase of the unwanted flavor compounds acetaldehyde and total diacetyl during the sequence of fermentations. Therefore, to achieve sustainable high cell density fermentations throughout the economical valuable process of serial repitching, adequate yeast growth is essential.

  12. Reprint of : Connection between wave transport through disordered 1D waveguides and energy density inside the sample: A maximum-entropy approach

    Mello, Pier A.; Shi, Zhou; Genack, Azriel Z.


    We study the average energy - or particle - density of waves inside disordered 1D multiply-scattering media. We extend the transfer-matrix technique that was used in the past for the calculation of the intensity beyond the sample to study the intensity in the interior of the sample by considering the transfer matrices of the two segments that form the entire waveguide. The statistical properties of the two disordered segments are found using a maximum-entropy ansatz subject to appropriate constraints. The theoretical expressions are shown to be in excellent agreement with 1D transfer-matrix simulations.

  13. Expansion of Endothelial Progenitor Cells in High Density Dot Culture of Rat Bone Marrow Cells

    Wang, Ling; Kretlow, James D.; Zhou, Guangdong; Cao, Yilin; Liu, Wei; Zhang, Wen Jie


    In vitro expansion of endothelial progenitor cells (EPCs) remains a challenge in stem cell research and its application. We hypothesize that high density culture is able to expand EPCs from bone marrow by mimicking cell-cell interactions of the bone marrow niche. To test the hypothesis, rat bone marrow cells were either cultured in high density (2×105 cells/cm2) by seeding total 9×105 cells into six high density dots or cultured in regular density (1.6×104 cells/cm2) with the same total number of cells. Flow cytometric analyses of the cells cultured for 15 days showed that high density cells exhibited smaller cell size and higher levels of marker expression related to EPCs when compared to regular density cultured cells. Functionally, these cells exhibited strong angiogenic potentials with better tubal formation in vitro and potent rescue of mouse ischemic limbs in vivo with their integration into neo-capillary structure. Global gene chip and ELISA analyses revealed up-regulated gene expression of adhesion molecules and enhanced protein release of pro-angiogenic growth factors in high density cultured cells. In summary, high density cell culture promotes expansion of bone marrow contained EPCs that are able to enhance tissue angiogenesis via paracrine growth factors and direct differentiation into endothelial cells. PMID:25254487

  14. Determining the maximum charging currents of lithium-ion cells for small charge quantities

    Grimsmann, F.; Gerbert, T.; Brauchle, F.; Gruhle, A.; Parisi, J.; Knipper, M.


    In order to optimize the operating parameters of battery management systems for electric and hybrid vehicles, great interest has been shown in achieving the maximum permissible charging currents during recuperation, without causing a cell damage due to lithium plating, in relation to the temperature, charge quantity and state of charge. One method for determining these recuperation currents is measuring the cell thickness, where excessively high charging currents can be detected by an irreversible increase in thickness. It is not possible to measure particularly small charge quantities by employing mechanic dial indicators, which have a limited resolution of 1 μm. This is why we developed a measuring setup that has a resolution limit of less than 10 nm using a high-resolution contactless inductance sensor. Our results show that the permissible charging current I can be approximated in relation to the charge quantity x by a correlating function I =a /√{(x) } which is compliant with the Arrhenius law. Small charge quantities therefore have an optimization potential for energy recovery during recuperation.

  15. Mast cell density in cardio-esophageal mucosa.

    Fatemeh E Mahjoub


    Full Text Available Mast cells are related to certain gastrointestinal complaints. Mast cell density has not been studied in cardio-esophageal region to the best of our knowledge. In this study we wanted to obtain an estimate of mast cell density in this region and compare it with mast cell density in antrum. From April 2007 till March 2010, we chose children (<14 years old who underwent upper endoscopy and from whom the taken biopsy was stated to be from lower third of esophagus, but in microscopic examination either cardio- esophageal mucosa or only cardiac mucosa was seen. Mast cells were counted by Giemsa stain at × 1000 magnification in 10 fields. 71 children (<14 years old were included in this study of which, 63.4% (n=45 were female and 36.6% (n=26 were male. The mean age of patients was 7.20 ± 4.21 years (range: 0.2 -14 years. The most common clinical manifestations were recurrent abdominal pain (64.8% and vomiting (23.9% followed by symptoms of gastro-esophageal reflux disorder, poor weight gain, hematemesis and dysphagia. The mean mast cell density in the cardiac mucosa was 33.41 ± 32.75 in 0.25 mm2 (range: 0-155, which was two times of that in antral mucosa. We found a significant but weak positive correlation at the 0.05 level between mast cell density of cardiac mucosa and the antrum. Higher mast cell counts were seen in cardiac mucosa in this study. Significant positive correlation between mast cell density of cardiac mucosa and the antrum could hint to a single underlying etiology for the inflammatory process in gastro- esophageal junction and gastric mucosa.

  16. Application of a maximum entropy method to estimate the probability density function of nonlinear or chaotic behavior in structural health monitoring data

    Livingston, Richard A.; Jin, Shuang


    Bridges and other civil structures can exhibit nonlinear and/or chaotic behavior under ambient traffic or wind loadings. The probability density function (pdf) of the observed structural responses thus plays an important role for long-term structural health monitoring, LRFR and fatigue life analysis. However, the actual pdf of such structural response data often has a very complicated shape due to its fractal nature. Various conventional methods to approximate it can often lead to biased estimates. This paper presents recent research progress at the Turner-Fairbank Highway Research Center of the FHWA in applying a novel probabilistic scaling scheme for enhanced maximum entropy evaluation to find the most unbiased pdf. The maximum entropy method is applied with a fractal interpolation formulation based on contraction mappings through an iterated function system (IFS). Based on a fractal dimension determined from the entire response data set by an algorithm involving the information dimension, a characteristic uncertainty parameter, called the probabilistic scaling factor, can be introduced. This allows significantly enhanced maximum entropy evaluation through the added inferences about the fine scale fluctuations in the response data. Case studies using the dynamic response data sets collected from a real world bridge (Commodore Barry Bridge, PA) and from the simulation of a classical nonlinear chaotic system (the Lorenz system) are presented in this paper. The results illustrate the advantages of the probabilistic scaling method over conventional approaches for finding the unbiased pdf especially in the critical tail region that contains the larger structural responses.

  17. Anorexia Reduces GFAP+ Cell Density in the Rat Hippocampus

    Daniel Reyes-Haro


    Full Text Available Anorexia nervosa is an eating disorder observed primarily in young women. The neurobiology of the disorder is unknown but recently magnetic resonance imaging showed a volume reduction of the hippocampus in anorexic patients. Dehydration-induced anorexia (DIA is a murine model that mimics core features of this disorder, including severe weight loss due to voluntary reduction in food intake. The energy supply to the brain is mediated by astrocytes, but whether their density is compromised by anorexia is unknown. Thus, the aim of this study was to estimate GFAP+ cell density in the main regions of the hippocampus (CA1, CA2, CA3, and dentate gyrus in the DIA model. Our results showed that GFAP+ cell density was significantly reduced (~20% in all regions of the hippocampus, except in CA1. Interestingly, DIA significantly reduced the GFAP+ cells/nuclei ratio in CA2 (−23% and dentate gyrus (−48%. The reduction of GFAP+ cell density was in agreement with a lower expression of GFAP protein. Additionally, anorexia increased the expression of the intermediate filaments vimentin and nestin. Accordingly, anorexia increased the number of reactive astrocytes in CA2 and dentate gyrus more than twofold. We conclude that anorexia reduces the hippocampal GFAP+ cell density and increases vimentin and nestin expression.

  18. Anorexia Reduces GFAP+ Cell Density in the Rat Hippocampus

    Labrada-Moncada, Francisco Emmanuel; Varman, Durairaj Ragu; Krüger, Janina; Morales, Teresa; Miledi, Ricardo; Martínez-Torres, Ataúlfo


    Anorexia nervosa is an eating disorder observed primarily in young women. The neurobiology of the disorder is unknown but recently magnetic resonance imaging showed a volume reduction of the hippocampus in anorexic patients. Dehydration-induced anorexia (DIA) is a murine model that mimics core features of this disorder, including severe weight loss due to voluntary reduction in food intake. The energy supply to the brain is mediated by astrocytes, but whether their density is compromised by anorexia is unknown. Thus, the aim of this study was to estimate GFAP+ cell density in the main regions of the hippocampus (CA1, CA2, CA3, and dentate gyrus) in the DIA model. Our results showed that GFAP+ cell density was significantly reduced (~20%) in all regions of the hippocampus, except in CA1. Interestingly, DIA significantly reduced the GFAP+ cells/nuclei ratio in CA2 (−23%) and dentate gyrus (−48%). The reduction of GFAP+ cell density was in agreement with a lower expression of GFAP protein. Additionally, anorexia increased the expression of the intermediate filaments vimentin and nestin. Accordingly, anorexia increased the number of reactive astrocytes in CA2 and dentate gyrus more than twofold. We conclude that anorexia reduces the hippocampal GFAP+ cell density and increases vimentin and nestin expression. PMID:27579183

  19. Reconstructing Atmospheric CO2 Through The Paleocene-Eocene Thermal Maximum Using Stomatal Index and Stomatal Density Values From Ginkgo adiantoides

    Barclay, R. S.; Wing, S. L.


    The Paleocene-Eocene Thermal Maximum (PETM) was a geologically brief interval of intense global warming 56 million years ago. It is arguably the best geological analog for a worst-case scenario of anthropogenic carbon emissions. The PETM is marked by a ~4-6‰ negative carbon isotope excursion (CIE) and extensive marine carbonate dissolution, which together are powerful evidence for a massive addition of carbon to the oceans and atmosphere. In spite of broad agreement that the PETM reflects a large carbon cycle perturbation, atmospheric concentrations of CO2 (pCO2) during the event are not well constrained. The goal of this study is to produce a high resolution reconstruction of pCO2 using stomatal frequency proxies (both stomatal index and stomatal density) before, during, and after the PETM. These proxies rely upon a genetically controlled mechanism whereby plants decrease the proportion of gas-exchange pores (stomata) in response to increased pCO2. Terrestrial sections in the Bighorn Basin, Wyoming, contain macrofossil plants with cuticle immediately bracketing the PETM, as well as dispersed plant cuticle from within the body of the CIE. These fossils allow for the first stomatal-based reconstruction of pCO2 near the Paleocene-Eocene boundary; we also use them to determine the relative timing of pCO2 change in relation to the CIE that defines the PETM. Preliminary results come from macrofossil specimens of Ginkgo adiantoides, collected from an ~200ka interval prior to the onset of the CIE (~230-30ka before), and just after the 'recovery interval' of the CIE. Stomatal index values decreased by 37% within an ~70ka time interval at least 100ka prior to the onset of the CIE. The decrease in stomatal index is interpreted as a significant increase in pCO2, and has a magnitude equivalent to the entire range of stomatal index adjustment observed in modern Ginkgo biloba during the anthropogenic CO2 rise during the last 150 years. The inferred CO2 increase prior to the

  20. Corneal Endothelial Cell Density and Morphology in Healthy Turkish Eyes

    Ceyhun Arıcı


    Full Text Available Purpose. To describe the normative values of corneal endothelial cell density, morphology, and central corneal thickness in healthy Turkish eyes. Methods. Specular microscopy was performed in 252 eyes of 126 healthy volunteers (M : F, 42 : 84. Parameters studied included mean endothelial cell density (MCD, mean cell area (MCA, coefficient of variation (CV in cell size, percentage of hexagonal cells, and central corneal thickness (CCT. Results. The mean age of volunteers was 44.3±13.5 (range, 20 to 70 years. There was a statistically significant decrease in MCD (P<0.001; correlation, −0.388 and percentage of hexagonal cells, (P<0.001; correlation, −0.199 with age. There was also a statistically significant increase in MCA (P<0.001; correlation, 0.363 with increasing age. There was no statistically significant difference in MCD, MCA, CV in cell size, percentage of hexagonal cells, and CCT between genders and there was also no significant difference in these parameters between fellow eyes of subjects. Conclusions. Normotive data for the endothelium in the Turkish population are reported. Endothelial cell density in the Turkish eyes is less than that described in the Japanese, American, Chinese, and Filipino eyes and higher than that described in Indian, Thai, and Iranian eyes.

  1. Solid Oxide Electrolysis Cells: Degradation at High Current Densities

    Knibbe, Ruth; Traulsen, Marie Lund; Hauch, Anne;


    The degradation of Ni/yttria-stabilized zirconia (YSZ)-based solid oxide electrolysis cells operated at high current densities was studied. The degradation was examined at 850°C, at current densities of −1.0, −1.5, and −2.0 A/cm2, with a 50:50 (H2O:H2) gas supplied to the Ni/YSZ hydrogen electrode...

  2. Active energy harvesting from microbial fuel cells at the maximum power point without using resistors.

    Wang, Heming; Park, Jae-Do; Ren, Zhiyong


    Microbial fuel cell (MFC) technology offers a sustainable approach to harvest electricity from biodegradable materials. Energy production from MFCs has been demonstrated using external resistors or charge pumps, but such methods can only dissipate energy through heat or receive electrons passively from the MFC without any controllability. This study developed a new approach and system that can actively extract energy from MFC reactors at any operating point without using any resistors, especially at the peak power point to maximize energy production. Results show that power harvesting from a recirculating-flow MFC can be well maintained by the maximum power point circuit (MPPC) at its peak power point, while a charge pump was not able to change operating point due to current limitation. Within 18-h test, the energy gained from the MPPC was 76.8 J, 76 times higher than the charge pump (1.0 J) that was commonly used in MFC studies. Both conditions resulted in similar organic removal, but the Coulombic efficiency obtained from the MPPC was 21 times higher than that of the charge pump. Different numbers of capacitors could be used in the MPPC for various energy storage requirements and power supply, and the energy conversion efficiency of the MPPC was further characterized to identify key factors for system improvement. This active energy harvesting approach provides a new perspective for energy harvesting that can maximize MFC energy generation and system controllability.

  3. High power density yeast catalyzed microbial fuel cells

    Ganguli, Rahul

    Microbial fuel cells leverage whole cell biocatalysis to convert the energy stored in energy-rich renewable biomolecules such as sugar, directly to electrical energy at high efficiencies. Advantages of the process include ambient temperature operation, operation in natural streams such as wastewater without the need to clean electrodes, minimal balance-of-plant requirements compared to conventional fuel cells, and environmentally friendly operation. These make the technology very attractive as portable power sources and waste-to-energy converters. The principal problem facing the technology is the low power densities compared to other conventional portable power sources such as batteries and traditional fuel cells. In this work we examined the yeast catalyzed microbial fuel cell and developed methods to increase the power density from such fuel cells. A combination of cyclic voltammetry and optical absorption measurements were used to establish significant adsorption of electron mediators by the microbes. Mediator adsorption was demonstrated to be an important limitation in achieving high power densities in yeast-catalyzed microbial fuel cells. Specifically, the power densities are low for the length of time mediator adsorption continues to occur. Once the mediator adsorption stops, the power densities increase. Rotating disk chronoamperometry was used to extract reaction rate information, and a simple kinetic expression was developed for the current observed in the anodic half-cell. Since the rate expression showed that the current was directly related to microbe concentration close to the electrode, methods to increase cell mass attached to the anode was investigated. Electrically biased electrodes were demonstrated to develop biofilm-like layers of the Baker's yeast with a high concentration of cells directly connected to the electrode. The increased cell mass did increase the power density 2 times compared to a non biofilm fuel cell, but the power density

  4. Waves in cell monolayer without proliferation: density determines cell velocity and wave celerity

    Tlili, S; Li, B; Cardoso, O; Ladoux, B; Delanoë-Ayari, H; Graner, F


    Collective cell migration contributes to morphogenesis, wound healing or tumor metastasis. Culturing epithelial monolayers on a substrate is an in vitro configuration suitable to quantitatively characterize such tissue migration by measuring cell velocity, density and cell-substrate interaction force. Inhibiting cell division, we limit cell density increase and favor steady cell migration, while by using long narrow strips we stabilise the migrating front shape, so that we observe migration over a day or more. In the monolayer bulk, the cell velocity is a function of the cell density, namely it increases as a linear function of the cell radius. At least ten periods of propagating velocity waves are detected with a high signal-to-noise ratio, enabling for their quantitative spatio-temporal analysis. Cell density displays waves, in phase opposition with the velocity, as predicted by mass conservation; similarly, cell-substrate force appear to display small amplitude waves, in phase quadrature with respect to ve...

  5. High Energy Density Regenerative Fuel Cell Systems for Terrestrial Applications

    Burke, Kenneth A.


    Regenerative Fuel Cell System (RFCS) technology for energy storage has been a NASA power system concept for many years. Compared to battery-based energy storage systems, RFCS has received relatively little attention or resources for development because the energy density and electrical efficiency were not sufficiently attractive relative to advanced battery systems. Even today, RFCS remains at a very low technology readiness level (TRL of about 2 indicating feasibility has been demonstrated). Commercial development of the Proton Exchange Membrane (PEM) fuel cells for automobiles and other terrestrial applications and improvements in lightweight pressure vessel design to reduce weight and improve performance make possible a high energy density RFCS energy storage system. The results from this study of a lightweight RFCS energy storage system for a remotely piloted, solar-powered, high altitude aircraft indicate an energy density up to 790 w-h/kg with electrical efficiency of 53.4% is attainable. Such an energy storage system would allow a solar-powered aircraft to carry hundreds of kilograms of payload and remain in flight indefinitely for use in atmospheric research, earth observation, resource mapping. and telecommunications. Future developments in the areas of hydrogen and oxygen storage, pressure vessel design, higher temperature and higher- pressure fuel cell operation, unitized regenerative fuel cells, and commercial development of fuel cell technology will improve both the energy density and electrical efficiency of the RFCS.

  6. Maximizing the power density of aqueous electrochemical flow cells with in operando deposition

    Goulet, Marc-Antoni; Ibrahim, Omar A.; Kim, Will H. J.; Kjeang, Erik


    To transition toward sustainable energy systems, next generation power sources must provide high power density at minimum cost. Using inexpensive and environmentally friendly fabrication methods, this work describes a room temperature electrochemical flow cell with a maximum power density of 2.01 W cm-2 or 13.4 W cm-3. In part, this is achieved by minimizing ohmic resistance through decreased electrode spacing, implementation of current collectors and improvement of electrolyte conductivity. The majority of the performance gain is provided by a novel in operando dynamic flowing deposition method for which the cell design has been optimized. Carbon nanotubes (CNTs) are deposited dynamically at the entrance of and within the carbon paper electrodes during operation of the cell. A natural equilibrium is reached between deposition and detachment of CNTs at which the electrochemical surface area and pore size distribution of the flow-through porous electrodes are greatly enhanced. In this way, the novel deposition method more than doubles the power density of the cell and sets a new performance benchmark for what is practically attainable with aqueous electrochemical flow cells. Overall, it is expected that the design and operation methods illustrated here will enable a wide range of electrochemical flow cell technologies to achieve optimal performance.

  7. Interaction of low density lipoproteins with rat liver cells

    L. Harkes (Leendert)


    textabstractThe most marked conclusion is the establishment of the important role of non-parenchymal cells in the catabolism of the low density lipoproteins by the rat liver. Because the liver is responsible for 70-80% of the removal of LDL from blood this conclusion can be extended to total LDL tur

  8. High cell density strategy for poly(3-hydroxybutyrate production by Cupriavidus necator

    J. L. Ienczak


    Full Text Available Poly(3-hydroxybutyrate (P(3HB is a carbon and intracellular storage source for different microorganisms and its production can achieve high productivities by means of high cell density cultures. The aim of this study was to propose a high cell density strategy for P(3HB production by Cupriavidus necator. The exponential growth phase demands an accurate control of the oxygen transfer system in the bioreactor, due to maximum specific growth rate (µXr, and, consequently, a maximum specific oxygen uptake rate (QO2, in addition to significant residual biomass (Xr growth in high cell density cultures. In this context, this work investigated the strategy for obtaining high cell density, with the inclusion of a linear growth phase for P(3HB production by C. necator in a fed-batch culture. The linear growth phase was included between the exponential growth phase and the P(3HB production phase as a strategy to reduce the specific growth rate (µXr and specific oxygen uptake rate (QO2, with constant residual biomass growth rate (d(V.Xr/dt = k = constant and linear increase of biomass. Three strategies of culture were performed. The results showed that a high residual biomass concentration (30 gXr.L-1 can be reached by the inclusion of the linear growth strategy and specific growth rates (µXr between 0.08 and 0.05 h-1, at the beginning of the production phase, are necessary to attain a high P(3HB productivity.

  9. Optimization of the cell seeding density and modeling of cell growth and metabolism using the modified Gompertz model for microencapsulated animal cell culture.

    Wen-tao, Qi; Ying, Zhang; Juan, Ma; Xin, Guo; Yu-bing, Xie; Wei, Wang; Xiaojun, Ma


    Cell microencapsulation is one of the promising strategies for the in vitro production of proteins or in vivo delivery of therapeutic products. In order to design and fabricate the optimized microencapsulated cell system, the Gompertz model was applied and modified to describe the growth and metabolism of microencapsulated cell, including substrate consumption and product formation. The Gompertz model successfully described the cell growth kinetics and the modified Gompertz models fitted the substrate consumption and product formation well. It was demonstrated that the optimal initial cell seeding density was about 4-5 x 10(6) cells/mL of microcapsule, in terms of the maximum specific growth rate, the glucose consumption potential and the product formation potential calculated by the Gompertz and modified Gompertz models. Modeling of cell growth and metabolism in microcapsules provides a guideline for optimizing the culture of microencapsulated cells.

  10. Hierarchical Load Tracking Control of a Grid-connected Solid Oxide Fuel Cell for Maximum Electrical Efficiency Operation

    Li, Yonghui; Wu, Qiuwei; Zhu, Haiyu


    Based on the benchmark solid oxide fuel cell (SOFC) dynamic model for power system studies and the analysis of the SOFC operating conditions, the nonlinear programming (NLP) optimization method was used to determine the maximum electrical efficiency of the grid-connected SOFC subject...

  11. Measuring density and compressibility of white blood cells and prostate cancer cells by microchannel acoustophoresis

    Barnkob, Rune; Augustsson, Per; Magnusson, Cecilia


    to determine the density and compressibility of individual cells enables the prediction and alteration of the separation outcome for a given cell mixture. We apply the method on white blood cells (WBCs) and DU145 prostate cancer cells (DUCs) aiming to improve isolation of circulating tumor cells from blood......We present a novel method for the determination of density and compressibility of individual particles and cells undergoing microchannel acoustophoresis in an arbitrary 2D acoustic field. Our method is a critical advancement within acoustophoretic separation of biological cells, as the ability......, an emerging tool in the monitoring and characterizing of metastatic cancer....

  12. Significance of maximum current for voltage boosting of microbial fuel cells in series

    An, Junyeong; Lee, Yoo Seok; Kim, Taeyoung; Chang, In Seop


    Differences in internal resistances or operational conditions that affect the current between series-connected MFC units are known to cause voltage reversal. In this work, we proved that voltage reversal does not happen when MFCs produce an identical maximum current (i.e., limiting current), even though their internal resistances may differ. Here, two MFCs having an internal resistance difference of 206 Ω produced an almost identical maximum current of 0.4 mA in non-stacked mode. When the MFCs were connected in series, there was no voltage reversal; the voltage at the maximum current of 0.37 mA ranged from 1 mV to 3 mV. This result clearly indicates that differences of internal resistances or operational conditions are not an essential prerequisite for occurrences of voltage reversal in stacked MFCs, and that the maximum current of MFCs may be a direct indicator for predicting voltage reversal occurrences prior to the series connection of MFCs.

  13. Direct alcohol fuel cells: toward the power densities of hydrogen-fed proton exchange membrane fuel cells.

    Chen, Yanxin; Bellini, Marco; Bevilacqua, Manuela; Fornasiero, Paolo; Lavacchi, Alessandro; Miller, Hamish A; Wang, Lianqin; Vizza, Francesco


    A 2 μm thick layer of TiO2 nanotube arrays was prepared on the surface of the Ti fibers of a nonwoven web electrode. After it was doped with Pd nanoparticles (1.5 mgPd  cm(-2) ), this anode was employed in a direct alcohol fuel cell. Peak power densities of 210, 170, and 160 mW cm(-2) at 80 °C were produced if the cell was fed with 10 wt % aqueous solutions of ethanol, ethylene glycol, and glycerol, respectively, in 2 M aqueous KOH. The Pd loading of the anode was increased to 6 mg cm(-2) by combining four single electrodes to produce a maximum peak power density with ethanol at 80 °C of 335 mW cm(-2) . Such high power densities result from a combination of the open 3 D structure of the anode electrode and the high electrochemically active surface area of the Pd catalyst, which promote very fast kinetics for alcohol electro-oxidation. The peak power and current densities obtained with ethanol at 80 °C approach the output of H2 -fed proton exchange membrane fuel cells.

  14. Nanofiber density determines endothelial cell behavior on hydrogel matrix

    Berti, Fernanda V., E-mail: [Department of Chemical and Food Engineering, Federal University of Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Rambo, Carlos R. [Department of Electrical Engineering, Federal University of Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Dias, Paulo F. [Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Porto, Luismar M. [Department of Chemical and Food Engineering, Federal University of Santa Catarina, 88040-900 Florianópolis, SC (Brazil)


    When cultured under static conditions, bacterial cellulose pellicles, by the nature of the polymer synthesis that involves molecular oxygen, are characterized by two distinct surface sides. The upper surface is denser in fibers (entangled) than the lower surface that shows greater surface porosity. Human umbilical vein endothelial cells (HUVECs) were used to exploit how the microarchitecture (i.e., surface porosity, fiber network structure, surface topology, and fiber density) of bacterial cellulose pellicle surfaces influence cell–biomaterial interaction and therefore cell behavior. Adhesion, cell ingrowth, proliferation, viability and cell death mechanisms were evaluated on the two pellicle surface sides. Cell behavior, including secondary necrosis, is influenced only by the microarchitecture of the surface, since the biomaterial is extremely pure (constituted of cellulose and water only). Cell–cellulose fiber interaction is the determinant signal in the cell–biomaterial responses, isolated from other frequently present interferences such as protein and other chemical traces usually present in cell culture matrices. Our results suggest that microarchitecture of hydrogel materials might determine the performance of biomedical products, such as bacterial cellulose tissue engineering constructs (BCTECs). - Highlights: • Topography of BC pellicle is relevant to determine endothelial cells' fate. • Cell–biomaterial response is affected by the topography of BC-pellicle surface. • Endothelial cells exhibit different behavior depending on the BC topography. • Apoptosis and necrosis of endothelial cells were affected by the BC topography.

  15. High-density lipoprotein endocytosis in endothelial cells

    Stefanie; Fruhwürth; Margit; Pavelka; Robert; Bittman; Werner; J; Kovacs; Katharina; M; Walter; Clemens; Rhrl; Herbert; Stangl


    AIM: To describe the way stations of high-density lipoprotein(HDL) uptake and its lipid exchange in endothelial cells in vitro and in vivo. METHODS: A combination of fluorescence microscopy using novel fluorescent cholesterol surrogates and electron microscopy was used to analyze HDL endocytosis in great detail in primary human endothelial cells. Further, HDL uptake was quantified using radio-labeled HDL particles. To validate the in vitro findings mice were injected with fluorescently labeled HDL and particle uptake in the liver was analyzed using fluorescencemicroscopy. RESULTS: HDL uptake occurred via clathrin-coated pits, tubular endosomes and multivesicular bodies in human umbilical vein endothelial cells. During uptake and resecretion, HDL-derived cholesterol was exchanged at a faster rate than cholesteryl oleate, resembling the HDL particle pathway seen in hepatic cells. In addition, lysosomes were not involved in this process and thus HDL degradation was not detectable. In vivo, we found HDL mainly localized in mouse hepatic endothelial cells. HDL was not detected in parenchymal liver cells, indicating that lipid transfer from HDL to hepatocytes occurs primarily via scavenger receptor, class B, type Ⅰ mediated selective uptake without concomitant HDL endocytosis. CONCLUSION: HDL endocytosis occurs via clathrincoated pits, tubular endosomes and multivesicular bodies in human endothelial cells. Mouse endothelial cells showed a similar HDL uptake pattern in vivo indicating that the endothelium is one major site of HDL endocytosis and transcytosis.

  16. Cortical cell and neuron density estimates in one chimpanzee hemisphere.

    Collins, Christine E; Turner, Emily C; Sawyer, Eva Kille; Reed, Jamie L; Young, Nicole A; Flaherty, David K; Kaas, Jon H


    The density of cells and neurons in the neocortex of many mammals varies across cortical areas and regions. This variability is, perhaps, most pronounced in primates. Nonuniformity in the composition of cortex suggests regions of the cortex have different specializations. Specifically, regions with densely packed neurons contain smaller neurons that are activated by relatively few inputs, thereby preserving information, whereas regions that are less densely packed have larger neurons that have more integrative functions. Here we present the numbers of cells and neurons for 742 discrete locations across the neocortex in a chimpanzee. Using isotropic fractionation and flow fractionation methods for cell and neuron counts, we estimate that neocortex of one hemisphere contains 9.5 billion cells and 3.7 billion neurons. Primary visual cortex occupies 35 cm(2) of surface, 10% of the total, and contains 737 million densely packed neurons, 20% of the total neurons contained within the hemisphere. Other areas of high neuron packing include secondary visual areas, somatosensory cortex, and prefrontal granular cortex. Areas of low levels of neuron packing density include motor and premotor cortex. These values reflect those obtained from more limited samples of cortex in humans and other primates.

  17. Very high density of CHO cells in perfusion by ATF or TFF in WAVE bioreactor™. Part I. Effect of the cell density on the process.

    Clincke, Marie-Françoise; Mölleryd, Carin; Zhang, Ye; Lindskog, Eva; Walsh, Kieron; Chotteau, Véronique


    High cell density perfusion process of antibody producing CHO cells was developed in disposable WAVE Bioreactor™ using external hollow fiber filter as cell separation device. Both "classical" tangential flow filtration (TFF) and alternating tangential flow system (ATF) equipment were used and compared. Consistency of both TFF- and ATF-based cultures was shown at 20-35 × 10(6) cells/mL density stabilized by cell bleeds. To minimize the nutrients deprivation and by-product accumulation, a perfusion rate correlated to the cell density was applied. The cells were maintained by cell bleeds at density 0.9-1.3 × 10(8) cells/mL in growing state and at high viability for more than 2 weeks. Finally, with the present settings, maximal cell densities of 2.14 × 10(8) cells/mL, achieved for the first time in a wave-induced bioreactor, and 1.32 × 10(8) cells/mL were reached using TFF and ATF systems, respectively. Using TFF, the cell density was limited by the membrane capacity for the encountered high viscosity and by the pCO2 level. Using ATF, the cell density was limited by the vacuum capacity failing to pull the highly viscous fluid. Thus, the TFF system allowed reaching higher cell densities. The TFF inlet pressure was highly correlated to the viscosity leading to the development of a model of this pressure, which is a useful tool for hollow fiber design of TFF and ATF. At very high cell density, the viscosity introduced physical limitations. This led us to recommend cell densities under 1.46 × 10(8) cell/mL based on the analysis of the theoretical distance between the cells for the present cell line. © 2013 American Institute of Chemical Engineers.

  18. A Semianalytical Model Using MODIS Data to Estimate Cell Density of Red Tide Algae (Aureococcus anophagefferens

    Lingling Jiang


    Full Text Available A multiband and a single-band semianalytical model were developed to predict algae cell density distribution. The models were based on cell density (N dependent parameterizations of the spectral backscattering coefficients, bb(λ, obtained from in situ measurements. There was a strong relationship between bb(λ and N, with a minimum regression coefficient of 0.97 at 488 nm and a maximum value of 0.98 at other bands. The cell density calculated by the multiband inversion model was similar to the field measurements of the coastal waters (the average relative error was only 8.9%, but it could not accurately discern the red tide from mixed pixels, and this led to overestimation of the area affected by the red tide. While the single-band inversion model is less precise than the former model in the high chlorophyll water, it could eliminate the impact of the suspended sediments and make more accurate estimates of the red tide area. We concluded that the two models both have advantages and disadvantages; these methods lay the foundation for developing a remote sensing forecasting system for red tides.

  19. Improving a free air breathing proton exchange membrane fuel cell through the Maximum Efficiency Point Tracking method

    Higuita Cano, Mauricio; Mousli, Mohamed Islam Aniss; Kelouwani, Sousso; Agbossou, Kodjo; Hammoudi, Mhamed; Dubé, Yves


    This work investigates the design and validation of a fuel cell management system (FCMS) which can perform when the fuel cell is at water freezing temperature. This FCMS is based on a new tracking technique with intelligent prediction, which combined the Maximum Efficiency Point Tracking with variable perturbation-current step and the fuzzy logic technique (MEPT-FL). Unlike conventional fuel cell control systems, our proposed FCMS considers the cold-weather conditions, the reduction of fuel cell set-point oscillations. In addition, the FCMS is built to respond quickly and effectively to the variations of electric load. A temperature controller stage is designed in conjunction with the MEPT-FL in order to operate the FC at low-temperature values whilst tracking at the same time the maximum efficiency point. The simulation results have as well experimental validation suggest that propose approach is effective and can achieve an average efficiency improvement up to 8%. The MEPT-FL is validated using a Proton Exchange Membrane Fuel Cell (PEMFC) of 500 W.

  20. Identification of PV solar cells and modules parameters using the genetic algorithms: Application to maximum power extraction

    Zagrouba, M.; Sellami, A.; Bouaicha, M. [Laboratoire de Photovoltaique, des Semi-conducteurs et des Nanostructures, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, Tunis, B.P. 95, 2050 Hammam-Lif (Tunisia); Ksouri, M. [Unite de Recherche RME-Groupe AIA, Institut National des Sciences Appliquees et de Technologie (Tunisia)


    In this paper, we propose to perform a numerical technique based on genetic algorithms (GAs) to identify the electrical parameters (I{sub s}, I{sub ph}, R{sub s}, R{sub sh}, and n) of photovoltaic (PV) solar cells and modules. These parameters were used to determine the corresponding maximum power point (MPP) from the illuminated current-voltage (I-V) characteristic. The one diode type approach is used to model the AM1.5 I-V characteristic of the solar cell. To extract electrical parameters, the approach is formulated as a non convex optimization problem. The GAs approach was used as a numerical technique in order to overcome problems involved in the local minima in the case of non convex optimization criteria. Compared to other methods, we find that the GAs is a very efficient technique to estimate the electrical parameters of PV solar cells and modules. Indeed, the race of the algorithm stopped after five generations in the case of PV solar cells and seven generations in the case of PV modules. The identified parameters are then used to extract the maximum power working points for both cell and module. (author)

  1. Theoretical maximum performance evaluation of third generation silicon solar cell consisting of nc-Si:H/a-Si:H quantum wells

    Tripathi, Brijesh; Sircar, Ratna


    The maximum performance of nc-Si:H/a-Si:H quantum well solar cell is theoretically evaluated by studying the spectral absorption of incident radiation with respect to the number of inserted nc-Si:H quantum well layers. Fundamental intrinsic properties of a-Si:H and nc-Si:H materials reported in literature have been used to evaluate the performance parameters. Enhanced spectral absorption is recorded due to insertion of nc-Si:H quantum well layers in the intrinsic region of a-Si:H solar cell. By inserting 50 QW layers of nc-Si:H in the intrinsic region of the a-Si:H solar cell, the short-circuit current density (JSC) increases by ∼100% as compared to the baseline whereas the open-circuit voltage (VOC) decreases by ∼38%. The decrease in VOC is explained on the basis of quasi-Fermi level separation under the illuminated state of solar cell. Theoretical maximum efficiency, having the combined effect of the increase in JSC and decrease in VOC, has increased by ∼24% in comparison with the baseline due to the use of QW as calculated using ideal carrier lifetime value. With a realistic carrier lifetime of the state-of-the-art a-Si:H solar cells, the addition of QWs do not yield any significant gain. From this study, it is concluded that a high carrier lifetime is required to gain a noteworthy benefit from the nc-Si:H/a-Si:H QWs.

  2. A supervision and control tool based on artificial intelligence for high cell density cultivations

    A. C. L. Horta


    Full Text Available High cell density cultivations of recombinant E. coli have been increasingly used for the production of heterologous proteins. However, it is a challenge to maintain these cultivations within the desired conditions, given that some variables such as dissolved oxygen concentration (DOC and feed flow rate are difficult to control. This paper describes the software SUPERSYS_HCDC, a tool developed to supervise fed-batch cultures of rE. coli with biomass concentrations up to 150 gDCW/L and cell productivities up to 9 gDCW.L-1.h-1. The tool includes automatic control of the DOC by integrated action of the stirrer speed as well as of the air and oxygen flow rates; automatic start-up of the feed flow of fresh medium (system based on a neural network committee; and automatic slowdown of feeding when oxygen consumption exceeds the maximum capacity of the oxygen supply.

  3. A ferroelectric DRAM cell for high-density NVRAM's

    Moazzami, Reza; Hu, Chenming; Shepherd, William H.


    The operation of a ferroelectric DRAM (dynamic random-access memory) cell for nonvolatile RAM (NVRAM) applications is described. Because polarization reversal only occurs during nonvolatile store/recall operations and not during read/write operations, ferroelectric fatigue is not a serious endurance problem. For a 3-V power supply, the worst-case effective silicon dioxide thickness of the unoptimized lead zirconate titanate film studied is less than 1.7 nm. The resistivity and endurance properties of ferroelectric films can be optimized by modifying the composition of the film. This cell can be the basis of a very-high-density NVRAM with practically no read/write cycle limit and at least 10 to the 10th nonvolatile store/recall cycles.

  4. Quantification of cell density in rat Achilles tendon

    Couppé, Christian; Svensson, René B; Heinemeier, Katja M


    Increased tendon cell nuclei density (TCND) has been proposed to induce tendon mechanical adaptations. However, it is unknown whether TCND is increased in tendon tissue after mechanical loading and whether such an increase can be quantified in a reliable manner. The aim of this study was to develop...... a reliable method for quantification of TCND and to investigate potential changes in TCND in rat Achilles tendons in response to 12 weeks of running. Eight adult male Sprague-Dawley rats ran (RUN) on a treadmill with 10° incline, 1 h/day, 5 days/wk (17-20 m/min) for 12 weeks (which improved tendon mechanical...... properties) and were compared with 11 control rats (SED). Tissue-Tek-embedded cryosections (10 µm) from the mid region of the Achilles tendon were cut longitudinally on a cryostat. Sections were stained with alcian blue and picrosirius red. One blinded investigator counted the number of tendon cell nuclei 2...

  5. Corneal endothelial cell density and morphology in Phramongkutklao Hospital

    Narumon Sopapornamorn


    Full Text Available Narumon Sopapornamorn1, Manapon Lekskul1, Suthee Panichkul21Department of Ophthalmology, Phramongkutklao Hospital, Bangkok, Thailand; 2Department of Obstetrics and Gynecology, Phramongkutklao College of Medicine, Bangkok, ThailandObjective: To describe the corneal endothelial density and morphology in patients of Phramongkutklao Hospital and the relationship between endothelial cell parameters and other factors.Methods: Four hundred and four eyes of 202 volunteers were included. Noncontact specular microscopy was performed after taking a history and testing the visual acuity, intraocular pressure measurement, Schirmer’s test and routine eye examination by slit lamp microscope. The studied parameters included mean endothelial cell density (MCD, coefficient of variation (CV, and percentage of hexagonality.Results: The mean age of volunteers was 45.73 years; the range being 20 to 80 years old. Their MCD (SD, mean percentage of CV (SD and mean (SD percentage of hexagonality were 2623.49(325 cell/mm2, 39.43(8.23% and 51.50(10.99%, respectively. Statistically, MCD decreased significantly with age (p < 0.01. There was a significant difference in the percentage of CV between genders. There was no statistical significance between parameters and other factors.Conclusion: The normative data of the corneal endothelium of Thai eyes indicated that, statistically, MCD decreased significantly with age. Previous studies have reported no difference in MCD, percentage of CV, and percentage of hexagonality between gender. Nevertheless, significantly different percentages of CV between genders were presented in this study.Keywords: Corneal endothelial cell, parameters, age, gender, smoking, Thailand

  6. Cell density-dependent changes in intracellular Ca2+ mobilization via the P2Y2 receptor in rat bone marrow stromal cells.

    Ichikawa, Jun; Gemba, Hisae


    Bone marrow stromal cells (BMSCs) are an interesting subject of research because they have characteristics of mesenchymal stem cells. We investigated intracellular Ca(2+) signaling in rat BMSCs. Agonists for purinergic receptors increased intracellular Ca(2+) levels ([Ca(2+)](i)). The order of potency followed ATP = UTP > ADP = UDP. ATP-induced rise in [Ca(2+)](i) was suppressed by U73122 and suramin, but not by pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), suggesting the functional expression of G protein-coupled P2Y(2) receptors. RT-PCR and immunohistochemical studies also showed the expression of P2Y(2) receptors. [Ca(2+)](i) response to UTP changed with cell density. The UTP-induced rise in [Ca(2+)](i) was greatest at high density. V(max) (maximum Ca(2+) response) and EC(50) (agonist concentration that evokes 50% of V(max)) suggest that the amount and property of P2Y(2) receptors were changed by cell density. Note that UTP induced Ca(2+) oscillation at only medium cell density. Pharmacological studies indicated that UTP-induced Ca(2+) oscillation required Ca(2+) influx by store-operated Ca(2+) entry. Carbenoxolone, a gap junction blocker, enhanced Ca(2+) oscillation. Immunohistochemical and quantitative real-time PCR studies revealed that proliferating cell nuclear antigen (PCNA)-positive cells declined but the mRNA expression level of the P2Y(2) receptor increased as cell density increased. Co-application of fetal calf serum with UTP induced Ca(2+) oscillation at high cell density. These results suggest that the different patterns observed for [Ca(2+)](i) mobilization with respect to cell density may be associated with cell cycle progression.

  7. Assessment of Microbial Fuel Cell Configurations and Power Densities

    Logan, Bruce E.


    Different microbial electrochemical technologies are being developed for a many diverse applications, including wastewater treatment, biofuel production, water desalination, remote power sources, and as biosensors. Current and energy densities will always be limited relative to batteries and chemical fuel cells, but these technologies have other advantages based on the self-sustaining nature of the microorganisms that can donate or accept electrons from an electrode, the range of fuels that can be used, and versatility in the chemicals that can be produced. The high cost of membranes will likely limit applications of microbial electrochemical technologies that might require a membrane. For microbial fuel cells, which do not need a membrane, questions remain on whether larger-scale systems can produce power densities similar to those obtained in laboratory-scale systems. It is shown here that configuration and fuel (pure chemicals in laboratory media versus actual wastewaters) remain the key factors in power production, rather than the scale of the application. Systems must be scaled up through careful consideration of electrode spacing and packing per unit volume of reactor.

  8. Flexible and Lightweight Fuel Cell with High Specific Power Density.

    Ning, Fandi; He, Xudong; Shen, Yangbin; Jin, Hehua; Li, Qingwen; Li, Da; Li, Shuping; Zhan, Yulu; Du, Ying; Jiang, Jingjing; Yang, Hui; Zhou, Xiaochun


    Flexible devices have been attracting great attention recently due to their numerous advantages. But the energy densities of current energy sources are still not high enough to support flexible devices for a satisfactory length of time. Although proton exchange membrane fuel cells (PEMFCs) do have a high-energy density, traditional PEMFCs are usually too heavy, rigid, and bulky to be used in flexible devices. In this research, we successfully invented a light and flexible air-breathing PEMFC by using a new design of PEMFC and a flexible composite electrode. The flexible air-breathing PEMFC with 1 × 1 cm(2) working area can be as light as 0.065 g and as thin as 0.22 mm. This new PEMFC exhibits an amazing specific volume power density as high as 5190 W L(-1), which is much higher than traditional (air-breathing) PEMFCs. Also outstanding is that the flexible PEMFC retains 89.1% of its original performance after being bent 600 times, and it retains its original performance after being dropped five times from a height of 30 m. Moreover, the research has demonstrated that when stacked, the flexible PEMFCs are also useful in mobile applications such as mobile phones. Therefore, our research shows that PEMFCs can be made light, flexible, and suitable for applications in flexible devices. These innovative flexible PEMFCs may also notably advance the progress in the PEMFC field, because flexible PEMFCs can achieve high specific power density with small size, small volume, low weight, and much lower cost; they are also much easier to mass produce.

  9. A new technique to measure the neutralizer cell gas line density applied to a DIII-D neutral beamline

    Kessler, D.N.; Hong, R.M.; Riggs, S.P.


    The DIII-D tokamak employs eight ion sources for plasma heating. In order to obtain the maximum neutralization of energetic ions (providing maximum neutral beam power) and reduce the heat load on beamline internal components caused by residual energetic ions, sufficient neutral gas must be injected into the beamline neutralizer cell. The neutral gas flow rate must be optimized, however, since excessive gas will increase power losses due to neutral beam scattering and reionization. It is important, therefore, to be able to determine the neutralizer cell gas line density. A new technique which uses the ion source suppressor grid current to obtain the neutralizer cell gas line density has been developed. The technique uses the fact that slow ions produced by beam-gas interactions in the neutralizer cell during beam extraction are attracted to the negative potential applied to the suppressor grid, inducing current flow in the grid. By removing the dependence on beam energy and beam current a normalized suppressor grid current function can be formed which is dependent only on the gas line density. With this technique it is possible to infer the gas line density on a shot by shot basis.

  10. Maximum geometrical hindrance to diffusion in brain extracellular space surrounding uniformly spaced convex cells.

    Tao, L; Nicholson, C


    Brain extracellular space (ECS) constitutes a porous medium in which diffusion is subject to hindrance, described by tortuosity, lambda = (D/D*)1/2, where D is the free diffusion coefficient and D* is the effective diffusion coefficient in brain. Experiments show that lambda is typically 1.6 in normal brain tissue although variations occur in specialized brain regions. In contrast, different theoretical models of cellular assemblies give ambiguous results: they either predict lambda-values similar to experimental data or indicate values of about 1.2. Here we constructed three different ECS geometries involving tens of thousands of cells and performed Monte Carlo simulation of 3-D diffusion. We conclude that the geometrical hindrance in the ECS surrounding uniformly spaced convex cells is independent of the cell shape and only depends on the volume fraction alpha (the ratio of the ECS volume to the whole tissue volume). This dependence can be described by the relation lambda = ((3-alpha)/2)1/2, indicating that the geometrical hindrance in such ECS cannot account for lambda > 1.225. Reasons for the discrepancy between the theoretical and experimental tortuosity values are discussed.

  11. F-cell levels are altered with erythrocyte density in sickle cell disease.

    Basu, Sumanta; Dash, Bisnu Prasad; Patel, Dilip Kumar; Chakravarty, Sudipa; Chakravarty, Amit; Banerjee, Debashis; Chakrabarti, Abhijit


    Lighter cells from density fractionated erythrocytes of sickle cell disease (SCD) patients carry higher amount of externalized phosphatidylserine (PS) and cell surface glycophorins compared to the denser counterparts. Further analysis also revealed that the denser cells contained higher levels of fetal hemoglobin (HbF) compared to the lighter cells, supported by the presence of larger number of F-cells in these populations. In this report, we have found direct evidence on the higher survival of the HbF rich erythrocytes in SCD.

  12. Angiogenesis and mast cell density as predictors of patient survival in squamous cell carcinoma of lung

    Ehsan Ullah


    Full Text Available Background: Measuring the microvascular and mast cell density in squamous cell carcinoma of lung and correlating them with the patient survival may be helpful to guide the use of cancer chemotherapeutic agents which target molecular mechanisms of tumour angiogenesis and mast cells. Materials and Methods: It was an observational study. It included 39 newly diagnosed, adult patients of pulmonary squamous cell carcinoma. Angiogenesis was determined by Chalkley′s method after immunohistochemical staining of micro-vessels with CD34. Mast cells per HPF were counted in Tolouidine blue stained sections. Results: Mean age of the patients was 58.33 ± 9.14 years. Male to female ratio was 9:1. Most (92.3% patients were current smokers. Majority of tumours (71.8% were localised to major bronchi and/or near to hilum and many of them (74.4% were poorly differentiated. Mean micro-vascular density was 11.80 ± 3.66 per HPF which showed strong negative correlation (r = -0.481, p =0.002 between microvascular density (MVD and tumour grade. Mean mast cell density was 1.60 ± 2.04 which showed strong negative correlation (r=-.683, p =0.0001 with grade. Angiogenesis and mast cell density were found to be positively correlated (r=0.439, p =0.005. High MVD, but not the MCD was associated with poor survival. Conclusion: Angiogenesis and mast cell density are positively correlated with each other however; only high MVD is associated with decreased survival. Thus, the anti-angiogenic agents may be useful in squamous cell carcinoma lung, especially the well differentiated tumours.

  13. Cell culture density affects the stemness gene expression of adipose tissue-derived mesenchymal stem cells.

    Kim, Dae Seong; Lee, Myoung Woo; Lee, Tae-Hee; Sung, Ki Woong; Koo, Hong Hoe; Yoo, Keon Hee


    The results of clinical trials using mesenchymal stem cells (MSCs) are controversial due to the heterogeneity of human MSCs and differences in culture conditions. In this regard, it is important to identify gene expression patterns according to culture conditions, and to determine how the cells are expanded and when they should be clinically used. In the current study, stemness gene expression was investigated in adipose tissue-derived MSCs (AT-MSCs) harvested following culture at different densities. AT-MSCs were plated at a density of 200 or 5,000 cells/cm(2). After 7 days of culture, stemness gene expression was examined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis. The proliferation rate of AT-MSCs harvested at a low density (~50% confluent) was higher than that of AT-MSCs harvested at a high density (~90% confluent). Although there were differences in the expression levels of stemness gene, such as octamer-binding transcription factor 4, nanog homeobox (Nanog), SRY-box 2, Kruppel like factor 4, v-myc avian myelocytomatosis viral oncogene homolog (c-Myc), and lin-28 homolog A, in the AT-MSCs obtained from different donors, RT-qPCR analysis demonstrated differential gene expression patterns according to the cell culture density. Expression levels of stemness genes, particularly Nanog and c-Myc, were upregulated in AT-MSCs harvested at a low density (~50% confluent) in comparison to AT-MSCs from the same donor harvested at a high density (~90% confluent). These results imply that culture conditions, such as the cell density at harvesting, modulate the stemness gene expression and proliferation of MSCs.

  14. α-Tocopherol modulates the low density lipoprotein receptor of human HepG2 cells

    Bottema Cynthia DK


    Full Text Available Abstract The aim of this study was to determine the effects of vitamin E (α-tocopherol on the low density lipoprotein (LDL receptor, a cell surface protein which plays an important role in controlling blood cholesterol. Human HepG2 hepatoma cells were incubated for 24 hours with increasing amounts of α, δ, or γ-tocopherol. The LDL receptor binding activity, protein and mRNA, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA reductase mRNA, cell cholesterol and cell lathosterol were measured. The effect of α-tocopherol was biphasic. Up to a concentration of 50 μM, α-tocopherol progressively increased LDL receptor binding activity, protein and mRNA to maximum levels 2, 4 and 6-fold higher than control, respectively. The HMG-CoA reductase mRNA and the cell lathosterol concentration, indices of cholesterol synthesis, were also increased by 40% over control by treatment with 50 μM α-tocopherol. The cell cholesterol concentration was decreased by 20% compared to control at 50 μM α-tocopherol. However, at α-tocopherol concentrations higher than 50 μM, the LDL receptor binding activity, protein and mRNA, the HMG-CoA reductase mRNA and the cell lathosterol and cholesterol concentrations all returned to control levels. The biphasic effect on the LDL receptor was specific for α-tocopherol in that δ and γ-tocopherol suppressed LDL receptor binding activity, protein and mRNA at all concentrations tested despite the cells incorporating similar amounts of the three homologues. In conclusion, α-tocopherol, exhibits a specific, concentration-dependent and biphasic "up then down" effect on the LDL receptor of HepG2 cells which appears to be at the level of gene transcription. Cholesterol synthesis appears to be similarly affected and the cell cholesterol concentration may mediate these effects.

  15. Kinetics of hydrolysis of 1-benzoyl-1,2,4-triazole in aqueous solution as a function of temperature near the temperature of maximum density, and the isochoric controversy

    Blandamer, MJ; Buurma, NJ; Engberts, JBFN; Reis, JCR; Buurma, Niklaas J.; Reis, João C.R.


    At temperatures above and below the temperature of maximum density, TMD, for water at ambient pressure, pairs of temperatures exist at which the molar volumes of water are equal. First-order rate constants for the pH-independent hydrolysis of 1-benzoyl-1,2,4-triazole in aqueous solution at pairs of

  16. Categorizing extent of tumor cell death response to cancer therapy using quantitative ultrasound spectroscopy and maximum mean discrepancy.

    Gangeh, Mehrdad J; Sadeghi-Naini, Ali; Diu, Michael; Tadayyon, Hadi; Kamel, Mohamed S; Czarnota, Gregory J


    Quantitative ultrasound (QUS) spectroscopic techniques in conjunction with maximum mean discrepancy (MMD) have been proposed to detect, and to classify noninvasively the levels of cell death in response to cancer therapy administration in tumor models. Evaluation of xenograft tumor responses to cancer treatments were carried out using conventional-frequency ultrasound at different times after chemotherapy exposure. Ultrasound data were analyzed using spectroscopic techniques and multi-parametric QUS spectral maps were generated. MMD was applied as a distance criterion, measuring alterations in each tumor in response to chemotherapy, and the extent of cell death was classified into less/more than 20% and 40% categories. Statistically significant differences were observed between "pre-" and "post-treatment" groups at different times after chemotherapy exposure, suggesting a high capability of proposed framework for detecting tumor response noninvasively. Promising results were also obtained for categorizing the extent of cell death response in each tumor using the proposed framework, with gold standard histological quantification of cell death as ground truth. The best classification results were obtained using MMD when applied on histograms of QUS parametric maps. In this case, classification accuracies of 84.7% and 88.2% were achieved for categorizing extent of tumor cell death into less/more than 20% and 40%, respectively.

  17. Maximum Fidelity

    Kinkhabwala, Ali


    The most fundamental problem in statistics is the inference of an unknown probability distribution from a finite number of samples. For a specific observed data set, answers to the following questions would be desirable: (1) Estimation: Which candidate distribution provides the best fit to the observed data?, (2) Goodness-of-fit: How concordant is this distribution with the observed data?, and (3) Uncertainty: How concordant are other candidate distributions with the observed data? A simple unified approach for univariate data that addresses these traditionally distinct statistical notions is presented called "maximum fidelity". Maximum fidelity is a strict frequentist approach that is fundamentally based on model concordance with the observed data. The fidelity statistic is a general information measure based on the coordinate-independent cumulative distribution and critical yet previously neglected symmetry considerations. An approximation for the null distribution of the fidelity allows its direct conversi...

  18. Maximum growth and survival of estrogen receptor-alpha positive breast cancer cells requires the Sin3A transcriptional repressor

    Alarid Elaine T


    Full Text Available Abstract Background Sin3A is an evolutionarily conserved transcriptional repressor which regulates gene expression as part of the multi-protein Sin3 repressive complex. It functions as a scaffold upon which proteins with enzymatic activity dock, including chromatin modifying histone deacetylases. Although regulation of transcription by Sin3A has been studied in detail, little is understood about the function of Sin3A in cancer cells. We previously showed that Sin3A is expressed in breast cancer cells and is a repressor of estrogen receptor-alpha (ERα, ESR1 gene expression. Here, we expand our previous studies to elucidate the function of Sin3A in the control of gene expression and growth of breast cancer cells. Results Analysis of gene expression following knockdown of Sin3A revealed changes in both basal and regulated gene transcription. Genes of known importance in breast cancer and estrogen signaling, including ERBB2, PGR, MYC, CLU, and NCOA2, were among those identified as Sin3A-responsive. The mechanism of Sin3A action varied among genes and was found to be mediated through both HDAC1/2 -dependent and -independent activities. Loss of Sin3A inhibited breast cancer cell growth by increasing apoptosis without affecting cell cycle progression. Analysis of both ERα-positive and ERα-negative cell lines revealed that the effects of Sin3A on growth were cell-type specific, as Sin3A expression promoted maximum growth of only the ERα-positive cells, and, notably, Sin3A protein itself was increased by estrogen. Further gene expression experiments revealed that Sin3A repressed expression of key apoptotic genes, including TRAIL, TRAILR1, CASP10, and APAF1, in ERα-positive, but not ERα-negative, cell lines, which could provide a mechanistic explanation for cell-type differences in growth. Conclusions This study identifies Sin3A as a regulator of gene expression, survival, and growth in ERα-positive breast cancer cells. Sin3A regulates the

  19. Density gradient centrifugation in urografin of Moraxella and Kingella cells and appendages.

    Frøholm, L O; Bøvre, K


    Purification of fimbriae (pili) by density gradient banding in Urografin medium was attempted. Moraxella nonliquefaciens and Kingella kingae fimbriae were of higher density than their cells of origin, but fimbrial fractions obtained by homogenization and differential centrifugation still banded together with presumed outer membrane fragments and some whole cells in Urografin gradients. The cellular density of genetic variants with different fimbriation/competence levels was also studied. For one strain of M. nonliquefaciens and two strains of K. kingae, cells harvested from agar plates tended to show several bands on isopycnic density gradient centrifugation, with slightly higher general density of fimbriated variants than non-fimbriated. A single density band could be observed with cells from log phase broth cultures of selected strains which showed no distinct difference between fimbriation or competence variants of each strain. Cells of M. nonliquefaciens and M. bovis showed comparable buoyant densities, whereas those of K. kingae had a higher density.

  20. Lens Epithelial Cell Proliferation and Cell Density in Human Age-related Cataract

    Xialin Liu; Yizhi Liu; Jianliang Zheng; Qiang Huang; Huling Zheng


    Purpose: To discuss the potential effect of the lens epithelial cell proliferation in age-related cataract.Methods: In vitro cell proliferation was assayed by MTT method to evaluate the lens epithelial cell density, index, and proliferation capacity in normal lens and all kinds of age-related cataract. Capsulotomy specimens from all kinds of patients who underwent cataract phacoemulsification extraction surgery were compared with the lens epithelial specimens from non-cataract lenses of Eye Bank eyes.Results: Lens epithelial cell density of central anterior capsule (LECD) in female normal lens was higher than that in male, LECD in nuclear cataract( > NⅢ ) was higher than that in normal lens, but in the mature cortical cataract, LF CD was lower. Mitotic index of three kinds of age-related cataracts in vivo had no statistical difference, neither did cell proliferation capacity of cultivated cells in vitro.Conclusion: The individual difference of lens epithelial cell density and proliferation capacity in vivo may be an important underlying cause for senile cataract in the cellular level, especially for nuclear cataract.

  1. TiO2 dye sensitized solar cell (DSSC): linear relationship of maximum power point and anthocyanin concentration

    Ahmadian, Radin


    This study investigated the relationship of anthocyanin concentration from different organic fruit species and output voltage and current in a TiO2 dye-sensitized solar cell (DSSC) and hypothesized that fruits with greater anthocyanin concentration produce higher maximum power point (MPP) which would lead to higher current and voltage. Anthocyanin dye solution was made with crushing of a group of fresh fruits with different anthocyanin content in 2 mL of de-ionized water and filtration. Using these test fruit dyes, multiple DSSCs were assembled such that light enters through the TiO2 side of the cell. The full current-voltage (I-V) co-variations were measured using a 500 Ω potentiometer as a variable load. Point-by point current and voltage data pairs were measured at various incremental resistance values. The maximum power point (MPP) generated by the solar cell was defined as a dependent variable and the anthocyanin concentration in the fruit used in the DSSC as the independent variable. A regression model was used to investigate the linear relationship between study variables. Regression analysis showed a significant linear relationship between MPP and anthocyanin concentration with a p-value of 0.007. Fruits like blueberry and black raspberry with the highest anthocyanin content generated higher MPP. In a DSSC, a linear model may predict MPP based on the anthocyanin concentration. This model is the first step to find organic anthocyanin sources in the nature with the highest dye concentration to generate energy.

  2. Regulation of cell proliferation and cell density by the inorganic phosphate transporter PiT1

    Byskov Kristina


    Full Text Available Abstact Background The inorganic phosphate (Pi transporter, PiT1 (SLC20A1, is ubiquitously expressed in mammalian cells. It has previously been shown that down-regulation of PiT1 severely impaired the proliferation of two transformed human cells lines, HepG2 and HeLa, and the tumorigenicity of HeLa cells in nude mice. Moreover, PiT1 knock-out mice do not survive past E12.5 and from E10.5, the embryos were found to be growth-retarded and showed reduced proliferation of liver cells. Isolated mouse embryonic fibroblasts with knocked out as well as reduced PiT1 expression levels also exhibited impaired proliferation. Together these results suggest that a certain level of PiT1 is important for proliferation. We have here investigated the role of PiT1 in regulation of cell proliferation using two strictly density-inhibited cells lines, the murine MC3T3-E1 and NIH3T3 cells. Results We found that knock-down of PiT1 in MC3T3-E1 cells led to impaired proliferation supporting that at least a certain level of PiT1 is important for wildtype level of proliferation. We, however, also observed that MC3T3-E1 and NIH3T3 cells themselves regulate their endogenous PiT1 mRNA levels with lower levels in general correlating with decreased proliferation/increased cell density. Moreover, over-expression of human PiT1 led to increased proliferation of both MC3T3-E1 and NIH3T3 cultures and resulted in higher cell densities in cultures of these two strictly density-inhibited cell lines. In addition, when we transformed NIH3T3 cells by cultivation in fetal bovine serum, cells over-expressing human PiT1 formed more colonies in soft agar than control cells. Conclusions We conclude that not only is a certain level of PiT1 necessary for normal cell division as suggested by previously published studies, rather the cellular PiT1 level is involved in regulating cell proliferation and cell density and an increased PiT1 expression can indeed make NIH3T3 cells more sensitive to

  3. Dietary Restriction reduces hippocampal neurogenesis and granule cell neuron density without affecting the density of mossy fibers.

    Staples, Miranda C; Fannon-Pavlich, McKenzie J; Mysore, Karthik K; Dutta, Rahul R; Ongjoco, Alexandria T; Quach, Leon W; Kharidia, Khush M; Somkuwar, Sucharita S; Mandyam, Chitra D


    The hippocampal formation undergoes significant morphological and functional changes after prolonged caloric and dietary restriction (DR). In this study we tested whether prolonged DR results in deleterious alterations in hippocampal neurogenesis, density of granule cell neurons and mossy fibers, all of which support plasticity in the dentate gyrus. Young adult animals either experienced free access to food (control condition), or every-other-day feeding regimen (DR condition) for 3 months. The number of Ki-67 cells and 28-day old 5-bromo-2'-deoxyuridine (BrdU) cells were quantified in the dorsal and ventral dentate gyrus to determine the effect of DR on cellular proliferation and survival of neural progenitor cells in the anatomically defined regions of the dentate gyrus. The density of granule cell neurons and synaptoporin were also quantified to determine the effect of DR on granule cell neurons and mossy fiber projections in the dentate gyrus. Our results show that DR increases cellular proliferation and concurrently reduces survival of newly born neurons in the ventral dentate gyrus without effecting the number of cells in the dorsal dentate gyrus. DR reduced density of granule cell neurons in the dorsal dentate gyrus. These alterations in the number of granule cell neurons did not affect mossy fiber density in DR animals, which was visualized as no differences in synaptoporin expression. Our findings demonstrate that granule cell neurons in the dentate gyrus are vulnerable to chronic DR and that the reorganization of granule cells in the dentate gyrus subregions is not producing concomitant alterations in dentate gyrus neuronal circuitry with this type of dietary restriction.

  4. Enhanced photocurrent density in graphene/Si based solar cell (GSSC) by optimizing active layer thickness

    Rosikhin, Ahmad, E-mail:; Hidayat, Aulia Fikri; Syuhada, Ibnu; Winata, Toto, E-mail: [Department of physics, physics of electronic materials research division Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung Jl. Ganesha 10, Bandung 40132, Jawa Barat – Indonesia (Indonesia)


    Thickness dependent photocurrent density in active layer of graphene/Si based solar cell has been investigated via analytical – simulation study. This report is a preliminary comparison of experimental and analytical investigation of graphene/Si based solar cell. Graphene sheet was interfaced with Si thin film forming heterojunction solar cell that was treated as a device model for photocurrent generator. Such current can be enhanced by optimizing active layer thickness and involving metal oxide as supporting layer to shift photons absorption. In this case there are two type of devices model with and without TiO{sub 2} in which the silicon thickness varied at 20 – 100 nm. All of them have examined and also compared with each other to obtain an optimum value. From this calculation it found that generated currents almost linear with thickness but there are saturated conditions that no more enhancements will be achieved. Furthermore TiO{sub 2} layer is effectively increases photon absorption but reducing device stability, maximum current is fluctuates enough. This may caused by the disturbance of excitons diffusion and resistivity inside each layer. Finally by controlling active layer thickness, it is quite useful to estimate optimization in order to develop the next solar cell devices.

  5. Cell culture density affects the proliferation activity of human adipose tissue stem cells.

    Kim, Dae Seong; Lee, Myoung Woo; Ko, Young Jong; Chun, Yong Hoon; Kim, Hyung Joon; Sung, Ki Woong; Koo, Hong Hoe; Yoo, Keon Hee


    In this study, we investigated the effect of cell density on the proliferation activity of human mesenchymal stem cells (MSCs) derived from adipose tissue (AT-MSCs) over time in culture. Passage #4 (P4) and #12 (P12) AT-MSCs from two donors were plated at a density of 200 (culture condition 1, CC1) or 5000 (culture condition 2, CC2) cells cm(-2) . After 7 days of incubation, P4 and P12 AT-MSCs cultured in CC1 were thin and spindle-shaped, whereas those cultured in CC2 had extensive cell-to-cell contacts and an expanded cell volume. In addition, P4 and P12 AT-MSCs in CC1 divided more than three times, while those in CC2 divided less than once on average. Flow cytometric analysis using 5(6)-carboxyfluorescein diacetate N-succinimidyl ester dye showed that the fluorescence intensity of AT-MSCs was lower in CC1 than in CC2. Furthermore, expression of proliferation-associated genes, such as CDC45L, CDC20A and KIF20A, in P4 AT-MSCs was higher in CC1 than in CC2, and this difference was also observed in P12 AT-MSCs. These data demonstrated that cell culture density affects the proliferation activity of MSCs, suggesting that it is feasible to design a strategy to prepare suitable MSCs using specific culture conditions.

  6. Construction of Larger Area Density-Uniform Plasma with Collisional Inductively Coupled Plasma Cells

    OUYANG Liang; LIU Wandong; BAI Xiaoyan; CHEN Zhipeng; WANG Huihui; LI LUO Chen; JI Liangliang; HU Bei


    The plasma density and electron temperature of a multi-source plasma system composed of several collisional inductively coupled plasma (ICP) cells were measured by a double-probe. The discharges of the ICP cells were shown to be independent of each other. Furthermore, the total plasma density at simultaneous multi-cell discharge was observed to be approximately equal to the summation of the plasma density when the cells discharge separately. Based on the linear summation phenomenon, it was shown that a larger area plasma with a uniform density and temperature profile could be constructed with multi-collisional ICP cells.

  7. Smooth muscle myosin regulation by serum and cell density in cultured rat lung connective tissue cells.

    Babij, P; Zhao, J; White, S; Woodcock-Mitchell, J; Mitchell, J; Absher, M; Baldor, L; Periasamy, M; Low, R B


    RNA and protein analyses were used to detect expression of SM1 and SM2 smooth muscle myosin heavy chain (MHC) in cultured adult rat lung connective tissue cells (RL-90). Smooth muscle MHC mRNA expression in confluent cells grown in 10% serum was approximately 50% of the level in adult stomach. Similar results were obtained in cells cultured at low density (25% confluency) in 1% serum. However, in low-density cultures transferred to 10% serum for 24 h, the level of MHC mRNA decreased to approximately 20% of that in adult stomach. Smooth muscle alpha-actin showed a pattern of expression similar to that for smooth muscle MHC. Expression of nonmuscle MHC-A mRNA was higher in all culture conditions compared to stomach. MHC-A mRNA expression was less in low-density cultures in low serum and increased when low-density cultures were transferred to 10% serum for 24 h. MHC-B mRNA expression was less in low- vs. high-density cultures. In contrast to MHC-A, however, MHC-B mRNA expression in low-density cultures was higher in low serum. Immunofluorescence and immunoblotting with SM1-specific antibody demonstrated the presence of the SM1 protein isoform as well as reactivity to a protein band migrating slightly faster than SM2. These results demonstrate that cultured rat lung connective tissue cells express smooth muscle MHC and that expression is modulated by culture conditions.

  8. Maximum diastolic potential of human induced pluripotent stem cell-derived cardiomyocytes depends critically on I(Kr).

    Doss, Michael Xavier; Di Diego, José M; Goodrow, Robert J; Wu, Yuesheng; Cordeiro, Jonathan M; Nesterenko, Vladislav V; Barajas-Martínez, Héctor; Hu, Dan; Urrutia, Janire; Desai, Mayurika; Treat, Jacqueline A; Sachinidis, Agapios; Antzelevitch, Charles


    Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) hold promise for therapeutic applications. To serve these functions, the hiPSC-CM must recapitulate the electrophysiologic properties of native adult cardiomyocytes. This study examines the electrophysiologic characteristics of hiPSC-CM between 11 and 121 days of maturity. Embryoid bodies (EBs) were generated from hiPS cell line reprogrammed with Oct4, Nanog, Lin28 and Sox2. Sharp microelectrodes were used to record action potentials (AP) from spontaneously beating clusters (BC) micro-dissected from the EBs (n = 103; 37°C) and to examine the response to 5 µM E-4031 (n = 21) or BaCl(2) (n = 22). Patch-clamp techniques were used to record I(Kr) and I(K1) from cells enzymatically dissociated from BC (n = 49; 36°C). Spontaneous cycle length (CL) and AP characteristics varied widely among the 103 preparations. E-4031 (5 µM; n = 21) increased Bazett-corrected AP duration from 291.8±81.2 to 426.4±120.2 msec (pKr) in all (11/11). Consistent with the electrophysiological data, RT-PCR and immunohistochemistry studies showed relatively poor mRNA and protein expression of I(K1) in the majority of cells, but robust expression of I(Kr.) In contrast to recently reported studies, our data point to major deficiencies of hiPSC-CM, with remarkable diversity of electrophysiologic phenotypes as well as pharmacologic responsiveness among beating clusters and cells up to 121 days post-differentiation (dpd). The vast majority have a maximum diastolic potential that depends critically on I(Kr) due to the absence of I(K1). Thus, efforts should be directed at producing more specialized and mature hiPSC-CM for future therapeutic applications.

  9. Human endothelial progenitor cells internalize high-density lipoprotein.

    Srisen, Kaemisa; Röhrl, Clemens; Meisslitzer-Ruppitsch, Claudia; Ranftler, Carmen; Ellinger, Adolf; Pavelka, Margit; Neumüller, Josef


    Endothelial progenitor cells (EPCs) originate either directly from hematopoietic stem cells or from a subpopulation of monocytes. Controversial views about intracellular lipid traffic prompted us to analyze the uptake of human high density lipoprotein (HDL), and HDL-cholesterol in human monocytic EPCs. Fluorescence and electron microscopy were used to investigate distribution and intracellular trafficking of HDL and its associated cholesterol using fluorescent surrogates (bodipy-cholesterol and bodipy-cholesteryl oleate), cytochemical labels and fluorochromes including horseradish peroxidase and Alexa Fluor® 568. Uptake and intracellular transport of HDL were demonstrated after internalization periods from 0.5 to 4 hours. In case of HDL-Alexa Fluor® 568, bodipy-cholesterol and bodipy-cholesteryl oleate, a photooxidation method was carried out. HDL-specific reaction products were present in invaginations of the plasma membrane at each time of treatment within endocytic vesicles, in multivesicular bodies and at longer periods of uptake, also in lysosomes. Some HDL-positive endosomes were arranged in form of "strings of pearl"- like structures. HDL-positive multivesicular bodies exhibited intensive staining of limiting and vesicular membranes. Multivesicular bodies of HDL-Alexa Fluor® 568-treated EPCs showed multilamellar intra-vacuolar membranes. At all periods of treatment, labeled endocytic vesicles and organelles were apparent close to the cell surface and in perinuclear areas around the Golgi apparatus. No HDL-related particles could be demonstrated close to its cisterns. Electron tomographic reconstructions showed an accumulation of HDL-containing endosomes close to the trans-Golgi-network. HDL-derived bodipy-cholesterol was localized in endosomal vesicles, multivesicular bodies, lysosomes and in many of the stacked Golgi cisternae and the trans-Golgi-network Internalized HDL-derived bodipy-cholesteryl oleate was channeled into the lysosomal intraellular

  10. Human endothelial progenitor cells internalize high-density lipoprotein.

    Kaemisa Srisen

    Full Text Available Endothelial progenitor cells (EPCs originate either directly from hematopoietic stem cells or from a subpopulation of monocytes. Controversial views about intracellular lipid traffic prompted us to analyze the uptake of human high density lipoprotein (HDL, and HDL-cholesterol in human monocytic EPCs. Fluorescence and electron microscopy were used to investigate distribution and intracellular trafficking of HDL and its associated cholesterol using fluorescent surrogates (bodipy-cholesterol and bodipy-cholesteryl oleate, cytochemical labels and fluorochromes including horseradish peroxidase and Alexa Fluor® 568. Uptake and intracellular transport of HDL were demonstrated after internalization periods from 0.5 to 4 hours. In case of HDL-Alexa Fluor® 568, bodipy-cholesterol and bodipy-cholesteryl oleate, a photooxidation method was carried out. HDL-specific reaction products were present in invaginations of the plasma membrane at each time of treatment within endocytic vesicles, in multivesicular bodies and at longer periods of uptake, also in lysosomes. Some HDL-positive endosomes were arranged in form of "strings of pearl"- like structures. HDL-positive multivesicular bodies exhibited intensive staining of limiting and vesicular membranes. Multivesicular bodies of HDL-Alexa Fluor® 568-treated EPCs showed multilamellar intra-vacuolar membranes. At all periods of treatment, labeled endocytic vesicles and organelles were apparent close to the cell surface and in perinuclear areas around the Golgi apparatus. No HDL-related particles could be demonstrated close to its cisterns. Electron tomographic reconstructions showed an accumulation of HDL-containing endosomes close to the trans-Golgi-network. HDL-derived bodipy-cholesterol was localized in endosomal vesicles, multivesicular bodies, lysosomes and in many of the stacked Golgi cisternae and the trans-Golgi-network Internalized HDL-derived bodipy-cholesteryl oleate was channeled into the lysosomal

  11. Density-dependent nerve growth factor regulation of Gs-alpha RNA in pheochromocytoma 12 cells.

    Tjaden, G; Aguanno, A; Kumar, R; Benincasa, D; Gubits, R M; Yu, H; Dolan, K P


    Nerve growth factor (NGF) affects levels of the alpha subunit of the stimulatory G protein (Gs-alpha) in pheochromocytoma 12 cells in a bidirectional, density-dependent manner. Cells grown at high density responded to NGF treatment with increased levels of Gs-alpha mRNA and protein. Conversely, in cells grown in low-density cultures, levels of this mRNA were lowered by NGF treatment. Images PMID:2160599

  12. Estimation of immune cell densities in immune cell conglomerates: an approach for high-throughput quantification.

    Niels Halama

    Full Text Available BACKGROUND: Determining the correct number of positive immune cells in immunohistological sections of colorectal cancer and other tumor entities is emerging as an important clinical predictor and therapy selector for an individual patient. This task is usually obstructed by cell conglomerates of various sizes. We here show that at least in colorectal cancer the inclusion of immune cell conglomerates is indispensable for estimating reliable patient cell counts. Integrating virtual microscopy and image processing principally allows the high-throughput evaluation of complete tissue slides. METHODOLOGY/PRINCIPAL FINDINGS: For such large-scale systems we demonstrate a robust quantitative image processing algorithm for the reproducible quantification of cell conglomerates on CD3 positive T cells in colorectal cancer. While isolated cells (28 to 80 microm(2 are counted directly, the number of cells contained in a conglomerate is estimated by dividing the area of the conglomerate in thin tissues sections (< or =6 microm by the median area covered by an isolated T cell which we determined as 58 microm(2. We applied our algorithm to large numbers of CD3 positive T cell conglomerates and compared the results to cell counts obtained manually by two independent observers. While especially for high cell counts, the manual counting showed a deviation of up to 400 cells/mm(2 (41% variation, algorithm-determined T cell numbers generally lay in between the manually observed cell numbers but with perfect reproducibility. CONCLUSION: In summary, we recommend our approach as an objective and robust strategy for quantifying immune cell densities in immunohistological sections which can be directly implemented into automated full slide image processing systems.

  13. Functional balance between T cell chimeric receptor density and tumor associated antigen density: CTL mediated cytolysis and lymphokine production.

    Weijtens, M E; Hart, E H; Bolhuis, R L


    Genetically engineered expression of tumor-specific single chain antibody chimeric receptors (ch-Rec) on human T lymphocytes endow these cells with the parental monoclonal antibody (mAb) dictated tumor specificity and may be useful for clinical immuno-genetherapy. Therefore it was of importance to assess how the densities of tumor-specific receptors and tumor associated antigens (TAA), respectively, affect primary human T lymphocyte functions in relation to target cell susceptibilities to lysis. We therefore studied the functional balance between ch-Rec densities on human T lymphocytes and TAA on tumor cells. The gene construct encoding a ch-Rec derived from (1) a renal carcinoma cell (RCC) specific mouse mAb (G250), and (2) the human signal transducing Fc(epsilon)RI gamma-chain was used. To obtain ch-RecHIGH-POS and ch-RecLOW-POS T lymphocytes, two distinct retroviral vectors were used to introduce the gene constructs into primary human T lymphocytes. Levels of ch-Rec-redirected T lymphocyte mediated tumor cell lysis, as well as lymphokine production were determined using RCC lines as target/stimulator cells, which express either no or increasing densities of the TAA. A functional and dynamic balance between ch-Rec densities on cytotoxic T lymphocytes (CTLs) on the one hand and TAA densities on RCCs on the other, was found. In short, ch-RecHIGH-POS CTLs are triggered by TAAHIGH-POS as well as TAALOW-POS RCCs to lyse tumor cells and produce (IFN-gamma and TNF-alpha) lymphokine. In contrast, ch-RecLOW-POS T lymphocytes are only triggered for cytolysis and lymphokine production by relatively TAAHIGH-POS RCCs. In conclusion, (1) the activation of T lymphocyte responses is co-determined by the expression levels of the ch-Rec on T lymphocytes and the TAA on tumor cells and (2) at relatively high T lymphocyte ch-Rec expression levels the CTLs lyse tumor cells with a wide range of TAA densities. Gene Therapy (2000) 7, 35-42.


    Anil V. Virkar


    Anode-supported solid oxide fuel cells with Ni + yttria-stabilized zirconia (YSZ) anode, YSZ-samaria-doped ceria (SDC) bi-layer electrolyte and Sr-doped LaCoO{sub 3} (LSC) + SDC cathode were fabricated. Fuel used consisted of H{sub 2} diluted with He, N{sub 2}, H{sub 2}O or CO{sub 2}, mixtures of H{sub 2} and CO, and mixtures of CO and CO{sub 2}. Cell performance was measured at 800 C with above-mentioned fuel gas mixtures and air as oxidant. For a given concentration of the diluent, the cell performance was higher with He as the diluent than with N{sub 2} as the diluent. Mass transport through porous Ni-YSZ anode for H{sub 2}-H{sub 2}O, CO-CO{sub 2} binary systems and H{sub 2}-H{sub 2}O-diluent gas ternary systems was analyzed using multicomponent gas diffusion theory. At high concentrations of the diluent, the maximum achievable current density was limited by the anodic concentration polarization. From this measured limiting current density, the corresponding effective gas diffusivity was estimated. Highest effective diffusivity was estimated for fuel gas mixtures containing H{sub 2}-H{sub 2}O-He mixtures ({approx}0.34 cm{sup 2}/s), and the lowest for CO-CO{sub 2} mixtures ({approx}0.07 cm{sup 2}/s). The lowest performance was observed with CO-CO{sub 2} mixture as a fuel, which in part was attributed to the lowest effective diffusivity of the fuels tested.

  15. Maximum diastolic potential of human induced pluripotent stem cell-derived cardiomyocytes depends critically on I(Kr.

    Michael Xavier Doss

    Full Text Available Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM hold promise for therapeutic applications. To serve these functions, the hiPSC-CM must recapitulate the electrophysiologic properties of native adult cardiomyocytes. This study examines the electrophysiologic characteristics of hiPSC-CM between 11 and 121 days of maturity. Embryoid bodies (EBs were generated from hiPS cell line reprogrammed with Oct4, Nanog, Lin28 and Sox2. Sharp microelectrodes were used to record action potentials (AP from spontaneously beating clusters (BC micro-dissected from the EBs (n = 103; 37°C and to examine the response to 5 µM E-4031 (n = 21 or BaCl(2 (n = 22. Patch-clamp techniques were used to record I(Kr and I(K1 from cells enzymatically dissociated from BC (n = 49; 36°C. Spontaneous cycle length (CL and AP characteristics varied widely among the 103 preparations. E-4031 (5 µM; n = 21 increased Bazett-corrected AP duration from 291.8±81.2 to 426.4±120.2 msec (p<0.001 and generated early afterdepolarizations in 8/21 preparations. In 13/21 BC, E-4031 rapidly depolarized the clusters leading to inexcitability. BaCl(2, at concentrations that selectively block I(K1 (50-100 µM, failed to depolarize the majority of clusters (13/22. Patch-clamp experiments revealed very low or negligible I(K1 in 53% (20/38 of the cells studied, but presence of I(Kr in all (11/11. Consistent with the electrophysiological data, RT-PCR and immunohistochemistry studies showed relatively poor mRNA and protein expression of I(K1 in the majority of cells, but robust expression of I(Kr. In contrast to recently reported studies, our data point to major deficiencies of hiPSC-CM, with remarkable diversity of electrophysiologic phenotypes as well as pharmacologic responsiveness among beating clusters and cells up to 121 days post-differentiation (dpd. The vast majority have a maximum diastolic potential that depends critically on I(Kr due to the absence of

  16. Information in a Network of Neuronal Cells: Effect of Cell Density and Short-Term Depression

    Onesto, Valentina


    Neurons are specialized, electrically excitable cells which use electrical to chemical signals to transmit and elaborate information. Understanding how the cooperation of a great many of neurons in a grid may modify and perhaps improve the information quality, in contrast to few neurons in isolation, is critical for the rational design of cell-materials interfaces for applications in regenerative medicine, tissue engineering, and personalized lab-on-a-chips. In the present paper, we couple an integrate-and-fire model with information theory variables to analyse the extent of information in a network of nerve cells. We provide an estimate of the information in the network in bits as a function of cell density and short-term depression time. In the model, neurons are connected through a Delaunay triangulation of not-intersecting edges; in doing so, the number of connecting synapses per neuron is approximately constant to reproduce the early time of network development in planar neural cell cultures. In simulations where the number of nodes is varied, we observe an optimal value of cell density for which information in the grid is maximized. In simulations in which the posttransmission latency time is varied, we observe that information increases as the latency time decreases and, for specific configurations of the grid, it is largely enhanced in a resonance effect.

  17. Application of maximum entropy method for the study of electron density distribution in SrS, BaS and PuS using powder X-ray data

    R Saravanan


    A study of the electronic structure of the three sulphides, SrS, BaS and PuS has been carried out in this work, using the powder X-ray intensity data from JCPDS powder diffraction data base. The statistical approach, MEM (maximum entropy method) is used for the analysis of the data for the electron density distribution in these materials and an attempt has been made to understand the bonding between the metal atom and the sulphur atom. The mid-bond electron density is found to be maximum for PuS among these three sulphides, being 0.584 e/Å3 at 2.397 Å. SrS is found to have the lowest electron density at the mid-bond (0.003 e/Å3) at 2.118 Å from the origin leaving it more ionic than the other two sulphides studied in this work. The two-dimensional electron density maps on (1 0 0) and (1 1 0) planes and the one-dimensional profiles along the bonding direction [1 1 1] are used for these analyses. The overall and individual Debye-Waller factors of atoms in these systems have also been studied and analyzed. The refinements of the observed X-ray data were carried out using standard softwares and also a routine written by the author.

  18. Application of maximum entropy method for the study of electron density distribution in SrS, BaS and PuS using powder X-ray data

    Saravanan, R.


    A study of the electronic structure of the three sulphides, SrS, BaS and PuS has been carried out in this work, using the powder X-ray intensity data from JCPDS powder diffraction data base. The statistical approach, MEM (maximum entropy method) is used for the analysis of the data for the electron density distribution in these materials and an attempt has been made to understand the bonding between the metal atom and the sulphur atom. The mid-bond electron density is found to be maximum for PuS among these three sulphides, being 0.584 e/Å^3 at 2.397 Å. SrS is found to have the lowest electron density at the mid-bond (0.003 e/Å^3) at 2.118 Å from the origin leaving it more ionic than the other two sulphides studied in this work. The two-dimensional electron density maps on (1 0 0) and (1 1 0) planes and the one-dimensional profiles along the bonding direction [1 1 1] are used for these analyses. The overall and individual Debye-Waller factors of atoms in these systems have also been studied and analyzed. The refinements of the observed X-ray data were carried out using standard softwares and also a routine written by the author.

  19. Dissecting the actin cortex density and membrane-cortex distance in living cells by super-resolution microscopy

    Clausen, M. P.; Colin-York, H.; Schneider, F.; Eggeling, C.; Fritzsche, M.


    Nanoscale spacing between the plasma membrane and the underlying cortical actin cytoskeleton profoundly modulates cellular morphology, mechanics, and function. Measuring this distance has been a key challenge in cell biology. Current methods for dissecting the nanoscale spacing either limit themselves to complex survey design using fixed samples or rely on diffraction-limited fluorescence imaging whose spatial resolution is insufficient to quantify distances on the nanoscale. Using dual-color super-resolution STED (stimulated-emission-depletion) microscopy, we here overcome this challenge and accurately measure the density distribution of the cortical actin cytoskeleton and the distance between the actin cortex and the membrane in live Jurkat T-cells. We found an asymmetric cortical actin density distribution with a mean width of 230 (+105/-125) nm. The spatial distances measured between the maximum density peaks of the cortex and the membrane were bi-modally distributed with mean values of 50  ±  15 nm and 120  ±  40 nm, respectively. Taken together with the finite width of the cortex, our results suggest that in some regions the cortical actin is closer than 10 nm to the membrane and a maximum of 20 nm in others.

  20. Self-induced metabolic state switching by a tunable cell density sensor for microbial isopropanol production.

    Soma, Yuki; Hanai, Taizo


    Chemicals production by engineered microorganisms often requires induction of target gene expression at an appropriate cell density to reduce conflict with cell growth. The lux system in Vibrio fischeri is a well-characterized model for cell density-dependent regulation of gene expression termed quorum sensing (QS). However, there are currently no reports for application of the lux system to microbial chemical production. Here, we constructed a synthetic lux system as a tunable cell density sensor-regulator using a synthetic lux promoter and a positive feedback loop in Escherichia coli. In this system, self-induction of a target gene expression is driven by QS-signal, and its threshold cell density can be changed depending on the concentration of a chemical inducer. We demonstrate auto-redirection of metabolic flux from central metabolic pathways toward a synthetic isopropanol pathway at a desired cell density resulting in a significant increase in isopropanol production.

  1. Effect of bottom clearance on performance of airlift bioreactor in high-density culture of Panax notoginseng cells.

    Hu, W; Zhong, J


    A fed-batch cultivation of Panax notoginseng cells in a concentric-tube airlift reactor was performed to study the effects of bottom clearance on cell growth and the production of ginseng saponin and polysaccharide. At a bottom clearance of 4.0 cm, the highest cell density of 29.1+/-1.6 g/l by dry weight was obtained, and the accumulation of saponin and polysaccharide also reached a maximum, i.e., 2.39+/-0.43 and 2.73+/-0.40 g/l, respectively. Cell growth and metabolite production were limited at a small (2.5 cm) or large (5.0 cm) bottom clearance. By analyzing the time constants of mixing, mass transfer and oxygen consumption, bulk gas-liquid oxygen transfer was found to be responsible for the growth limitation at a small bottom clearance (2.5 cm). The decrease in cell density at a large bottom clearance (5.0 cm) was related to cell sedimentation at the reactor bottom. This work is beneficial for the scale-up and efficient operation of the airlift reactor in cell cultures.

  2. Multicellular automaticity of cardiac cell monolayers: effects of density and spatial distribution of pacemaker cells

    Elber Duverger, James; Boudreau-Béland, Jonathan; Le, Minh Duc; Comtois, Philippe


    Self-organization of pacemaker (PM) activity of interconnected elements is important to the general theory of reaction-diffusion systems as well as for applications such as PM activity in cardiac tissue to initiate beating of the heart. Monolayer cultures of neonatal rat ventricular myocytes (NRVMs) are often used as experimental models in studies on cardiac electrophysiology. These monolayers exhibit automaticity (spontaneous activation) of their electrical activity. At low plated density, cells usually show a heterogeneous population consisting of PM and quiescent excitable cells (QECs). It is therefore highly probable that monolayers of NRVMs consist of a heterogeneous network of the two cell types. However, the effects of density and spatial distribution of the PM cells on spontaneous activity of monolayers remain unknown. Thus, a simple stochastic pattern formation algorithm was implemented to distribute PM and QECs in a binary-like 2D network. A FitzHugh-Nagumo excitable medium was used to simulate electrical spontaneous and propagating activity. Simulations showed a clear nonlinear dependency of spontaneous activity (occurrence and amplitude of spontaneous period) on the spatial patterns of PM cells. In most simulations, the first initiation sites were found to be located near the substrate boundaries. Comparison with experimental data obtained from cardiomyocyte monolayers shows important similarities in the position of initiation site activity. However, limitations in the model that do not reflect the complex beat-to-beat variation found in experiments indicate the need for a more realistic cardiomyocyte representation.

  3. IL-21 dependent IgE production in human and mouse in vitro culture systems is cell density and cell division dependent and is augmented by IL-10.

    Caven, Timothy H; Shelburne, Anne; Sato, Jun; Chan-Li, Yee; Becker, Steve; Conrad, Daniel H


    IL-21 is known to enhance immunoglobulin production using human in vitro models. Using either PBMC or purified tonsilar B cells both stimulated with anti-CD40, IL-4+/-IL-21, this enhancement was shown to correlate with increased cell division especially for IgE and to a lesser extent for IgM and total IgG. Cell division was monitored by CFSE staining and maximum cell division was found at low initial cell plating densities. A correlation between increased cell division and IL-10-mediated enhancement of IgE production was also seen; however, increased cell division plays a smaller role with IL-10 than IL-21. This is further emphasized in that when IL-10 and IL-21 were added together there was a further synergistic increase in IgE seen, but no accompanying further increase in cell division. The mouse system was also examined for IL-21 effects as a function of cell concentration, and as in humans, IL-21 added to murine cells increased IgE production over IL-4/CD40 stimulated cells at lower cell concentrations; however, IL-21 significantly reduced IgE at higher plated cell concentrations.

  4. Cell receptor and surface ligand density effects on dynamic states of adhering circulating tumor cells.

    Zheng, Xiangjun; Cheung, Luthur Siu-Lun; Schroeder, Joyce A; Jiang, Linan; Zohar, Yitshak


    Dynamic states of cancer cells moving under shear flow in an antibody-functionalized microchannel are investigated experimentally and theoretically. The cell motion is analyzed with the aid of a simplified physical model featuring a receptor-coated rigid sphere moving above a solid surface with immobilized ligands. The motion of the sphere is described by the Langevin equation accounting for the hydrodynamic loadings, gravitational force, receptor-ligand bindings, and thermal fluctuations; the receptor-ligand bonds are modeled as linear springs. Depending on the applied shear flow rate, three dynamic states of cell motion have been identified: (i) free motion, (ii) rolling adhesion, and (iii) firm adhesion. Of particular interest is the fraction of captured circulating tumor cells, defined as the capture ratio, via specific receptor-ligand bonds. The cell capture ratio decreases with increasing shear flow rate with a characteristic rate. Based on both experimental and theoretical results, the characteristic flow rate increases monotonically with increasing either cell-receptor or surface-ligand density within certain ranges. Utilizing it as a scaling parameter, flow-rate dependent capture ratios for various cell-surface combinations collapse onto a single curve described by an exponential formula.

  5. Collagen Matrix Density Drives the Metabolic Shift in Breast Cancer Cells

    Brett A. Morris


    Full Text Available Increased breast density attributed to collagen I deposition is associated with a 4–6 fold increased risk of developing breast cancer. Here, we assessed cellular metabolic reprogramming of mammary carcinoma cells in response to increased collagen matrix density using an in vitro 3D model. Our initial observations demonstrated changes in functional metabolism in both normal mammary epithelial cells and mammary carcinoma cells in response to changes in matrix density. Further, mammary carcinoma cells grown in high density collagen matrices displayed decreased oxygen consumption and glucose metabolism via the tricarboxylic acid (TCA cycle compared to cells cultured in low density matrices. Despite decreased glucose entry into the TCA cycle, levels of glucose uptake, cell viability, and ROS were not different between high and low density matrices. Interestingly, under high density conditions the contribution of glutamine as a fuel source to drive the TCA cycle was significantly enhanced. These alterations in functional metabolism mirrored significant changes in the expression of metabolic genes involved in glycolysis, oxidative phosphorylation, and the serine synthesis pathway. This study highlights the broad importance of the collagen microenvironment to cellular expression profiles, and shows that changes in density of the collagen microenvironment can modulate metabolic shifts of cancer cells.

  6. Collagen Matrix Density Drives the Metabolic Shift in Breast Cancer Cells.

    Morris, Brett A; Burkel, Brian; Ponik, Suzanne M; Fan, Jing; Condeelis, John S; Aguire-Ghiso, Julio A; Castracane, James; Denu, John M; Keely, Patricia J


    Increased breast density attributed to collagen I deposition is associated with a 4-6 fold increased risk of developing breast cancer. Here, we assessed cellular metabolic reprogramming of mammary carcinoma cells in response to increased collagen matrix density using an in vitro 3D model. Our initial observations demonstrated changes in functional metabolism in both normal mammary epithelial cells and mammary carcinoma cells in response to changes in matrix density. Further, mammary carcinoma cells grown in high density collagen matrices displayed decreased oxygen consumption and glucose metabolism via the tricarboxylic acid (TCA) cycle compared to cells cultured in low density matrices. Despite decreased glucose entry into the TCA cycle, levels of glucose uptake, cell viability, and ROS were not different between high and low density matrices. Interestingly, under high density conditions the contribution of glutamine as a fuel source to drive the TCA cycle was significantly enhanced. These alterations in functional metabolism mirrored significant changes in the expression of metabolic genes involved in glycolysis, oxidative phosphorylation, and the serine synthesis pathway. This study highlights the broad importance of the collagen microenvironment to cellular expression profiles, and shows that changes in density of the collagen microenvironment can modulate metabolic shifts of cancer cells.

  7. Estimation of current density distribution of PAFC by analysis of cell exhaust gas

    Kato, S.; Seya, A. [Fuji Electric Co., Ltd., Ichihara-shi (Japan); Asano, A. [Fuji Electric Corporate, Ltd., Yokosuka-shi (Japan)


    To estimate distributions of Current densities, voltages, gas concentrations, etc., in phosphoric acid fuel cell (PAFC) stacks, is very important for getting fuel cells with higher quality. In this work, we leave developed a numerical simulation tool to map out the distribution in a PAFC stack. And especially to Study Current density distribution in the reaction area of the cell, we analyzed gas composition in several positions inside a gas outlet manifold of the PAFC stack. Comparing these measured data with calculated data, the current density distribution in a cell plane calculated by the simulation, was certified.

  8. Effects of plating density and culture time on bone marrow stromal cell characteristics.

    Neuhuber, Birgit; Swanger, Sharon A; Howard, Linda; Mackay, Alastair; Fischer, Itzhak


    Bone marrow stromal cells (MSC) are multipotent adult stem cells that have emerged as promising candidates for cell therapy in disorders including cardiac infarction, stroke, and spinal cord injury. While harvesting methods used by different laboratories are relatively standard, MSC culturing protocols vary widely. This study is aimed at evaluating the effects of initial plating density and total time in culture on proliferation, cell morphology, and differentiation potential of heterogeneous MSC cultures and more homogeneous cloned subpopulations. Rat MSC were plated at 20, 200, and 2000 cells/cm(2) and grown to 50% confluency. The numbers of population doublings and doubling times were determined within and across multiple passages. Changes in cell morphology and differentiation potential to adipogenic, chondrogenic, and osteogenic lineages were evaluated and compared among early, intermediate, and late passages, as well as between heterogeneous and cloned MSC populations. We found optimal cell growth at a plating density of 200 cells/cm(2). Cultures derived from all plating densities developed increased proportions of flat cells over time. Assays for chondrogenesis, osteogenesis, and adipogenesis showed that heterogeneous MSC plated at all densities sustained the potential for all three mesenchymal phenotypes through at least passage 5; the flat subpopulation lost adipogenic and chondrogenic potential. Our findings suggest that the initial plating density is not critical for maintaining a well-defined, multipotent MSC population. Time in culture, however, affects cell characteristics, suggesting that cell expansion should be limited, especially until the specific characteristics of different MSC subpopulations are better understood.

  9. Cell Growth on ("Janus") Density Gradients of Bifunctional Zeolite L Crystals.

    Kehr, Nermin Seda; Motealleh, Andisheh; Schäfer, Andreas H


    Nanoparticle density gradients on surfaces have attracted interest as two-dimensional material surfaces that can mimic the complex nano-/microstructure of the native extracellular matrix, including its chemical and physical gradients, and can therefore be used to systematically study cell-material interactions. In this respect, we report the preparation of density gradients made of bifunctional zeolite L crystals on glass surfaces and the effects of the density gradient and biopolymer functionalization of zeolite L crystals on cell adhesion. We also describe how we created "Janus" density gradient surfaces by gradually depositing two different types of zeolite L crystals that were functionalized and loaded with different chemical groups and guest molecules onto the two distinct sides of the same glass substrate. Our results show that more cells adhered on the density gradient of biopolymer-coated zeolites than on uncoated ones. The number of adhered cells increased up to a certain surface coverage of the glass by the zeolite L crystals, but then it decreased beyond the zeolite density at which a higher surface coverage decreased fibroblast cell adhesion and spreading. Additionally, cell experiments showed that cells gradually internalized the guest-molecule-loaded zeolite L crystals from the underlying density gradient containing bifunctional zeolite L crystals.

  10. Cells determine cell density using a small protein bound to a unique tissue-specific phospholipid

    Christopher J. Petzold


    Full Text Available Cell density is the critical parameter controlling tendon morphogenesis. Knowing its neighbors allows a cell to regulate correctly its proliferation and collagen production. A missing link to understanding this process is a molecular description of the sensing mechanism. Previously, this mechanism was shown in cell culture to rely on a diffusible factor (SNZR [sensor] with an affinity for the cell layer. This led to purifying conditioned medium over 4 columns and analyzing the final column fractions for band intensity on SDS gels versus biological activity – a 16 kD band strongly correlated between assays. N-terminal sequencing – EPLAVVDL – identified a large gene (424 AA, extremely conserved between chicken and human. In this paper we probe whether this is the correct gene. Can the predicted large protein be cleaved to a smaller protein? EPLAVVDL occurs towards the C-terminus and cleavage would create a small 94 AA protein. This protein would run at ∼10 kD, so what modifications or cofactor binding accounts for its running at 16 kD on SDS gels? This protein has no prominent hydrophobic regions, so can it be secreted? To validate its role, the chicken cDNA for this gene was tagged with myc and his and transfected into a human osteosarcoma cell line (U2OS. U2OS cells expressed the gene but not passively: differentiating into structures resembling spongy bone and expressing alkaline phosphatase, an early bone marker. Intracellularly, two bands were observed by Western blotting: the full length protein and a smaller form (26 kD. Outside the cell, a small band (28 kD was detected, although it was 40% larger than expected, as well as multiple larger bands. These larger forms could be converted to the predicted smaller protein (94 AA + tags by changing salt concentrations and ultrafiltering – releasing a cofactor to the filtrate while leaving a protein factor in the retentate. Using specific degradative enzymes and mass spectrometry, the

  11. Density, proportion, and dendritic coverage of retinal ganglion cells of the common marmoset (Callithrix jacchus jacchus

    F.L. Gomes


    Full Text Available We performed a quantitative analysis of M and P cell mosaics of the common-marmoset retina. Ganglion cells were labeled retrogradely from optic nerve deposits of Biocytin. The labeling was visualized using horseradish peroxidase (HRP histochemistry and 3-3'diaminobenzidine as chromogen. M and P cells were morphologically similar to those found in Old- and New-World primates. Measurements were performed on well-stained cells from 4 retinas of different animals. We analyzed separate mosaics for inner and outer M and P cells at increasing distances from the fovea (2.5-9 mm of eccentricity to estimate cell density, proportion, and dendritic coverage. M cell density decreased towards the retinal periphery in all quadrants. M cell density was higher in the nasal quadrant than in other retinal regions at similar eccentricities, reaching about 740 cells/mm² at 2.5 mm of temporal eccentricity, and representing 8-14% of all ganglion cells. P cell density increased from peripheral to more central regions, reaching about 5540 cells/mm² at 2.5 mm of temporal eccentricity. P cells represented a smaller proportion of all ganglion cells in the nasal quadrant than in other quadrants, and their numbers increased towards central retinal regions. The M cell coverage factor ranged from 5 to 12 and the P cell coverage factor ranged from 1 to 3 in the nasal quadrant and from 5 to 12 in the other quadrants. These results show that central and peripheral retinal regions differ in terms of cell class proportions and dendritic coverage, and their properties do not result from simply scaling down cell density. Therefore, differences in functional properties between central and peripheral vision should take these distinct regional retinal characteristics into account.

  12. Application of dielectric spectroscopy for monitoring high cell density in monoclonal antibody producing CHO cell cultivations.

    Párta, László; Zalai, Dénes; Borbély, Sándor; Putics, Akos


    The application of dielectric spectroscopy was frequently investigated as an on-line cell culture monitoring tool; however, it still requires supportive data and experience in order to become a robust technique. In this study, dielectric spectroscopy was used to predict viable cell density (VCD) at industrially relevant high levels in concentrated fed-batch culture of Chinese hamster ovary cells producing a monoclonal antibody for pharmaceutical purposes. For on-line dielectric spectroscopy measurements, capacitance was scanned within a wide range of frequency values (100-19,490 kHz) in six parallel cell cultivation batches. Prior to detailed mathematical analysis of the collected data, principal component analysis (PCA) was applied to compare dielectric behavior of the cultivations. PCA analysis resulted in detecting measurement disturbances. By using the measured spectroscopic data, partial least squares regression (PLS), Cole-Cole, and linear modeling were applied and compared in order to predict VCD. The Cole-Cole and the PLS model provided reliable prediction over the entire cultivation including both the early and decline phases of cell growth, while the linear model failed to estimate VCD in the later, declining cultivation phase. In regards to the measurement error sensitivity, remarkable differences were shown among PLS, Cole-Cole, and linear modeling. VCD prediction accuracy could be improved in the runs with measurement disturbances by first derivative pre-treatment in PLS and by parameter optimization of the Cole-Cole modeling.

  13. The density of the cell sap and endoplasm of Nitellopsis and Chara

    Wayne, R.; Staves, M. P.


    We measured the densities of the cell sap, endoplasm and cell wall of Nitellopsis obtusa and Chara corallina using interference microscopy, refractometry, immersion refractometry, equilibrium sedimentation and chemical microanalysis techniques. These values are important for the determination of many rheological properties of the cytoplasm as well as for understanding buoyancy regulation, dispersal mechanisms and how cells respond to gravity. The average densities of the cell sap, endoplasm and cell wall are 1,006.9, 1,016.7 and 1,371 kg m-3 for Nitellopsis and 1,005.0, 1,013.9, and 1,355.3 kg m-3 for Chara.

  14. Effect of bone graft density on in vitro cell behavior with enamel matrix derivative.

    Miron, Richard J; Caluseru, Oana M; Guillemette, Vincent; Zhang, Yufeng; Buser, Daniel; Chandad, Fatiha; Sculean, Anton


    Bone replacement grafting materials play an important role in regenerative dentistry. Despite a large array of tested bone-grafting materials, little information is available comparing the effects of bone graft density on in vitro cell behavior. Therefore, the aim of the present study is to compare the effects of cells seeded on bone grafts at low and high density in vitro for osteoblast adhesion, proliferation, and differentiation. The response of osteoblasts to the presence of a growth factor (enamel matrix derivative, (EMD)) in combination with low (8 mg per well) or high (100 mg per well) bone grafts (BG; natural bone mineral, Bio-Oss®) density, was studied and compared for osteoblast cell adhesion, proliferation, and differentiation as assessed by real-time PCR. Standard tissue culture plastic was used as a control with and without EMD. The present study demonstrates that in vitro testing of bone-grafting materials is largely influenced by bone graft seeding density. Osteoblast adhesion was up to 50 % lower when cells were seeded on high-density BG when compared to low-density BG and control tissue culture plastic. Furthermore, proliferation was affected in a similar manner whereby cell proliferation on high-density BG (100 mg/well) was significantly increased when compared to that on low-density BG (8 mg/well). In contrast, cell differentiation was significantly increased on high-density BG as assessed by real-time PCR for markers collagen 1 (Col 1), alkaline phosphatase (ALP), and osteocalcin (OC) as well as alizarin red staining. The effects of EMD on osteoblast adhesion, proliferation, and differentiation further demonstrated that the bone graft seeding density largely controls in vitro results. EMD significantly increased cell attachment only on high-density BG, whereas EMD was able to further stimulate cell proliferation and differentiation of osteoblasts on control culture plastic and low-density BG when compared to high-density BG. The results

  15. FGF7 and cell density are required for final differentiation of pancreatic amylase-positive cells from human ES cells.

    Takizawa-Shirasawa, Sakiko; Yoshie, Susumu; Yue, Fengming; Mogi, Akimi; Yokoyama, Tadayuki; Tomotsune, Daihachiro; Sasaki, Katsunori


    The major molecular signals of pancreatic exocrine development are largely unknown. We examine the role of fibroblast growth factor 7 (FGF7) in the final induction of pancreatic amylase-containing exocrine cells from induced-pancreatic progenitor cells derived from human embryonic stem (hES) cells. Our protocol consisted in three steps: Step I, differentiation of definitive endoderm (DE) by activin A treatment of hES cell colonies; Step II, differentiation of pancreatic progenitor cells by re-plating of the cells of Step I onto 24-well plates at high density and stimulation with all-trans retinoic acid; Step III, differentiation of pancreatic exocrine cells with a combination of FGF7, glucagon-like peptide 1 and nicotinamide. The expression levels of pancreatic endodermal markers such as Foxa2, Sox17 and gut tube endoderm marker HNF1β were up-regulated in both Step I and II. Moreover, in Step III, the induced cells expressed pancreatic markers such as amylase, carboxypeptidase A and chymotrypsinogen B, which were similar to those in normal human pancreas. From day 8 in Step III, cells immunohistochemically positive for amylase and for carboxypeptidase A, a pancreatic exocrine cell product, were induced by FGF7. Pancreatic progenitor Pdx1-positive cells were localized in proximity to the amylase-positive cells. In the absence of FGF7, few amylase-positive cells were identified. Thus, our three-step culture protocol for human ES cells effectively induces the differentiation of amylase- and carboxypeptidase-A-containing pancreatic exocrine cells.

  16. Endothelial cell density after deep anterior lamellar keratoplasty (Melles technique)

    Van Dooren, BTH; Mulder, PGH; Nieuwendaal, CP; Beekhuis, WH; Melles, GRJ

    PURPOSE: To measure the recipient endothelial cell loss after the Melles technique for deep anterior lamellar keratoplasty. METHODS: In 21 eyes of 21 patients, a deep anterior lamellar keratoplasty procedure was performed. Before surgery and at 6, 12, and 24 months after surgery, specular microscopy

  17. Cell descent caused by boundary curvature of a high topographical structure for a device that changes cell density

    Okutani, Chihiro; Wagatsuma, Akira; Mabuchi, Kunihiko; Hoshino, Takayuki


    Noninvasive techniques of controlling cell migration on substrates are widely useful for tissue engineering. However, the cell migration controls of previous studies were not enough for collecting cells locally. To solve this problem, in this work, we report the C2C12 mouse myoblast cell migration difference (descend or be repelled) by changing the curvature of the boundary of a topographical structure when the cells move from a flat surface to the boundary. 69% of the cells coming across a round boundary — the curvature radius of which was 50 µm — descended into the hole. In contrast, no cells descended into a groove with a linear boundary. Moreover, we demonstrated the cell spatial density change from the difference at the boundary. This finding will provide a new device that will enable us to manipulate spatial cell density noninvasively for tissue engineering.

  18. Current progress in high cell density yeast bioprocesses for bioethanol production.

    Westman, Johan O; Franzén, Carl Johan


    High capital costs and low reaction rates are major challenges for establishment of fermentation-based production systems in the bioeconomy. Using high cell density cultures is an efficient way to increase the volumetric productivity of fermentation processes, thereby enabling faster and more robust processes and use of smaller reactors. In this review, we summarize recent progress in the application of high cell density yeast bioprocesses for first and second generation bioethanol production. High biomass concentrations obtained by retention of yeast cells in the reactor enables easier cell reuse, simplified product recovery and higher dilution rates in continuous processes. High local cell density cultures, in the form of encapsulated or strongly flocculating yeast, furthermore obtain increased tolerance to convertible fermentation inhibitors and utilize glucose and other sugars simultaneously, thereby overcoming two additional hurdles for second generation bioethanol production. These effects are caused by local concentration gradients due to diffusion limitations and conversion of inhibitors and sugars by the cells, which lead to low local concentrations of inhibitors and glucose. Quorum sensing may also contribute to the increased stress tolerance. Recent developments indicate that high cell density methodology, with emphasis on high local cell density, offers significant advantages for sustainable second generation bioethanol production.

  19. Effects of diabetic keratopathy on corneal optical density, central corneal thickness, and corneal endothelial cell counts.

    Gao, Feng; Lin, Tao; Pan, Yingzhe


    Diabetic keratopathy is an ocular complication that occurs with diabetes. In the present study, the effect of diabetic keratopathy on corneal optical density, central corneal thickness, and corneal endothelial cell count was investigated. One hundred and eighty diabetic patients (360 eyes) were enrolled in the study during the period from March, 2012 to March, 2013. The patients were divided into three age groups: 10 years, with 60 patients per group (120 eyes). During the same period, 60 healthy cases (120 eyes) were selected and labeled as the normal control group. The Pentacam was used to measure the corneal optical density, and central corneal thickness. Specular microscopy was used to examine the corneal endothelial cell density. The coefficient of partial correlation was used to control age and correlate the analysis between the corneal optical density, corneal endothelial cell density, and central corneal thickness. The stage of the disease, the medial and intimal corneal optical density and central corneal thickness was analyzed in the diabetes group. The corneal optical density in the diabetes group increased compared with that of the normal control group. The medial and intimal corneal optical density and central corneal thickness were positively correlated with the course of the disease. However, the corneal endothelial cell density was not associated with the course of diabetes. There was a positive association between the medial and intimal corneal optical density and central corneal thickness of the diabetic patients. In conclusion, the results of the present study show that medial and intimal corneal optical density and central corneal thickness were sensitive indicators for early diabetic keratopathy.

  20. Measuring the mass, density, and size of particles and cells using a suspended microchannel resonator

    Godin, Michel; Bryan, Andrea K.; Burg, Thomas P.; Babcock, Ken; Manalis, Scott R.


    We demonstrate the measurement of mass, density, and size of cells and nanoparticles using suspended microchannel resonators. The masses of individual particles are quantified as transient frequency shifts, while the particles transit a microfluidic channel embedded in the resonating cantilever. Mass histograms resulting from these data reveal the distribution of a population of heterogeneously sized particles. Particle density is inferred from measurements made in different carrier fluids since the frequency shift for a particle is proportional to the mass difference relative to the displaced solution. We have characterized the density of polystyrene particles, Escherichia coli, and human red blood cells with a resolution down to 10-4g/cm3.

  1. Reduced Neurite Density in Neuronal Cell Cultures Exposed to Serum of Patients with Bipolar Disorder

    Wollenhaupt-Aguiar, Bianca; Pfaffenseller, Bianca; Chagas, Vinicius de Saraiva; Castro, Mauro A A; Passos, Ives Cavalcante; Kauer-Sant’Anna, Márcia; Kapczinski, Flavio


    Background: Increased inflammatory markers and oxidative stress have been reported in serum among patients with bipolar disorder (BD). The aim of this study is to assess whether biochemical changes in the serum of patients induces neurotoxicity in neuronal cell cultures. Methods: We challenged the retinoic acid-differentiated human neuroblastoma SH-SY5Y cells with the serum of BD patients at early and late stages of illness and assessed neurite density and cell viability as neurotoxic endpoints. Results: Decreased neurite density was found in neurons treated with the serum of patients, mostly patients at late stages of illness. Also, neurons challenged with the serum of late-stage patients showed a significant decrease in cell viability. Conclusions: Our findings showed that the serum of patients with bipolar disorder induced a decrease in neurite density and cell viability in neuronal cultures. PMID:27207915

  2. Density-dependent expression of keratins in transformed rat liver cell lines.

    Troyanovsky, S M; Bannikov, G A; Montesano, R; Vasiliev, J M


    Immunomorphological examination of the distribution of three keratins in cultured rat liver-derived epithelial cell lines of the IAR series was performed in order to find out the effects of neoplastic evolution on the expression of these epithelium-specific markers. Specific monoclonal antibodies were used to reveal various intermediate filament proteins: keratins with molecular masses of 55, 49 or 40 kD (K55, K49 or K40), and vimentin. The expression of keratins was negligible in sparse and dense cultures of non-transformed lines, which had typical epithelial morphology. The examined keratins were also absent in the sparse cultures of transformed lines, which have lost partially or completely the morphological features of epithelia. However, cells in dense cultures of most transformed lines contained numerous keratin filaments. It is suggested that the paradoxical increase of keratin expression after transformation is due to increased saturation density of transformed cultures; this high density favours the expression. As shown by the experiments with culture wounding, the effects of density are local and reversible. While K55 was present in all the cells of dense cultures, the expression of the other two keratins was dependent on the cell position within these cultures. It is suggested that the expression of the latter two keratins, besides high cell density, also requires the presence (K40) or the absence (K49) of cell-substratum contacts. Possible mechanisms of the effects of cell density on the expression of keratins are discussed.

  3. Generalized Maximum Entropy

    Cheeseman, Peter; Stutz, John


    A long standing mystery in using Maximum Entropy (MaxEnt) is how to deal with constraints whose values are uncertain. This situation arises when constraint values are estimated from data, because of finite sample sizes. One approach to this problem, advocated by E.T. Jaynes [1], is to ignore this uncertainty, and treat the empirically observed values as exact. We refer to this as the classic MaxEnt approach. Classic MaxEnt gives point probabilities (subject to the given constraints), rather than probability densities. We develop an alternative approach that assumes that the uncertain constraint values are represented by a probability density {e.g: a Gaussian), and this uncertainty yields a MaxEnt posterior probability density. That is, the classic MaxEnt point probabilities are regarded as a multidimensional function of the given constraint values, and uncertainty on these values is transmitted through the MaxEnt function to give uncertainty over the MaXEnt probabilities. We illustrate this approach by explicitly calculating the generalized MaxEnt density for a simple but common case, then show how this can be extended numerically to the general case. This paper expands the generalized MaxEnt concept introduced in a previous paper [3].

  4. Conjunctival Goblet Cell Density Following Cataract Surgery With Diclofenac Versus Diclofenac and Rebamipide: A Randomized Trial.

    Kato, Kumiko; Miyake, Kensaku; Kondo, Nagako; Asano, Sayaka; Takeda, Junko; Takahashi, Akiko; Takashima, Yuko; Kondo, Mineo


    To determine the effects of topical diclofenac or betamethasone with concomitant application of topical rebamipide on the conjunctival goblet cell density in eyes after cataract surgery. Randomized clinical trial. Eighty patients who were scheduled for cataract surgery. Patients were randomized into 4 groups according to the postoperative topical drugs to be given; Group A, diclofenac alone; Group B, diclofenac and rebamipide; Group C, betamethasone alone; and Group D, betamethasone and rebamipide. Impression cytology was performed before and at 1 month after the surgery, and the mean density of goblet cells was determined. The mean (± SD) density of goblet cells before the surgery in Group A was 257.0 ± 188.7 cells/mm(2), and it decreased significantly to 86.5 ± 76.7 cells/mm(2) at 1 month after the surgery (P = .002). In Group B, the goblet cell density was not statistically different between before (238.5 ± 116.6 cells/mm(2)) and at 1 month after the surgery (211.3 ± 184.4 cells/mm(2), P = .55). In Groups C and D, the mean density of goblet cells was decreased at 1 month after the surgery, but the decreases were not significant (P = .11 and P = .52, respectively). After cataract surgery with postoperative topical diclofenac, the conjunctival goblet cell density was significantly reduced, and this reduction was blocked by the concomitant use of topical rebamipide. These results suggest that the concomitant use of topical rebamipide with nonsteroidal anti-inflammatory drugs is beneficial, especially in cases with postoperative dry eyes. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  5. Minimally modified low density lipoprotein induces monocyte chemotactic protein 1 in human endothelial cells and smooth muscle cells.

    Cushing, S D; Berliner, J A; Valente, A. J.; Territo, M C; Navab, M; Parhami, F; Gerrity, R; Schwartz, C J; Fogelman, A M


    After exposure to low density lipoprotein (LDL) that had been minimally modified by oxidation (MM-LDL), human endothelial cells (EC) and smooth muscle cells (SMC) cultured separately or together produced 2- to 3-fold more monocyte chemotactic activity than did control cells or cells exposed to freshly isolated LDL. This increase in monocyte chemotactic activity was paralleled by increases in mRNA levels for a monocyte chemotactic protein 1 (MCP-1) that is constitutively produced by the human ...

  6. An economical biorefinery process for propionic acid production from glycerol and potato juice using high cell density fermentation.

    Dishisha, Tarek; Ståhl, Åke; Lundmark, Stefan; Hatti-Kaul, Rajni


    An economically sustainable process was developed for propionic acid production by fermentation of glycerol using Propionibacterium acidipropionici and potato juice, a by-product of starch processing, as a nitrogen/vitamin source. The fermentation was done as high-cell-density sequential batches with cell recycle. Propionic acid production and glycerol consumption rates were dependent on initial biomass concentration, and reached a maximum of 1.42 and 2.30 g L(-1) h(-1), respectively, from 50 g L(-1) glycerol at initial cell density of 23.7 gCDW L(-1). Halving the concentration of nitrogen/vitamin source resulted in reduction of acetic and succinic acids yields by ~39% each. At glycerol concentrations of 85 and 120 g L(-1), respectively, 43.8 and 50.8 g L(-1) propionic acid were obtained at a rate of 0.88 and 0.29 g L(-1) h(-1) and yield of 84 and 78 mol%. Succinic acid was 13 g% of propionic acid and could represent a potential co-product covering the cost of nitrogen/vitamin source. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Is there any role of mast cell density and microvessel density in cervical squamous cell carcinoma? A histologic study with special reference to CD-34 immunomarker staining

    Santosh Kumar Mondal


    Full Text Available Background: Mast cells are involved in induction of angiogenesis in the early-stages of tumor development and in modulating blood vessel growth in the later stages of tumor progression. Aims and Objectives: This study was carried out to evaluate the association between mast cell density (MCD and microvessel density (MVD in carcinoma in situ (CIS, microinvasive carcinoma (CA and invasive squamous cell CA of cervix. Materials and Methods: Six cases of CIS, four cases of microinvasive CA and 38 cases of invasive CA were studied over a period of 2 years from August, 2011 to June, 2013. Ten control samples were included in the study. Routine histologic examination was done. Toluidine blue stain was used for MCD determination. Immunohistochemical analysis with CD-34 was done for assessing MVD. Student′s t-test was used to calculate the statistical significance of MCD and MVD. Results: Both MCD and MVD increased from normal samples through CIS to invasive cervical CA. In the four cases of microinvasive CA, the MCD and MVD were more than that of the control samples, but less than that of the six cases of CIS. Conclusion: There is a correlation between mast cell accumulation and angiogenesis in CIS, microinvasive CA and invasive cervical squamous cell CA. MCD and MVD in invasive CA exceed those in CIS and microinvasive CA. It gives us an opportunity to postulate that therapeutic strategies against mast cell mediators and angiogenesis may be of benefit in patients of early-stage cervical CA.

  8. Degradation of Solid Oxide Electrolysis Cells Operated at High Current Densities

    Tao, Youkun; Ebbesen, Sune Dalgaard; Mogensen, Mogens Bjerg


    In this work the durability of solid oxide cells for co-electrolysis of steam and carbon dioxide (45 % H2O + 45 % CO2 + 10 % H2) at high current densities was investigated. The tested cells are Ni-YSZ electrode supported, with a YSZ electrolyte and either a LSM-YSZ or LSCF-CGO oxygen electrode...

  9. Autonomous Bacterial Localization and Gene Expression Based on Nearby Cell Receptor Density


    Upon detection of B1–5 mM AI-2, these cells express T7 polymerase that amplifies the native lsr operon response by overexpressing DsRed (see...2 for initiating gene expression (lsr operon ). (B) Indicated densities of PCI-15B or HEK293 cells were seeded to wells followed by mouse anti-EGFR

  10. Age-related decrease in rod bipolar cell density of the human retina: an immunohistochemical study

    P Aggarwal; T C Nag; S Wadhwa


    During normal ageing, the rods (and other neurones) undergo a significant decrease in density in the human retina from the fourth decade of life onward. Since the rods synapse with the rod bipolar cells in the outer plexiform layer, a decline in rod density (mainly due to death) may ultimately cause an associated decline of the neurones which, like the rod bipolar cells, are connected to them. The rod bipolar cells are selectively stained with antibodies to protein kinase C-. This study examined if rod bipolar cell density changes with ageing of the retina, utilizing donor human eyes (age: 6–91 years). The retinas were fixed and their temporal parts from the macula to the mid-periphery sectioned and processed for protein kinase C- immunohistochemistry. The density of the immunopositive rod bipolar cells was estimated in the mid-peripheral retina (eccentricity: 3–5 mm) along the horizontal temporal axis. The results show that while there is little change in the density of the rod bipolar cells from 6 to 35 years (2.2%), the decline during the period from 35 to 62 years is about 21% and between seventh and tenth decades, it is approximately 27%.

  11. Completion of cell division is associated with maximum telomerase activity in naturally synchronized cultures of the green alga Desmodesmus quadricauda.

    Ševčíková, Tereza; Bišová, Kateřina; Fojtová, Miloslava; Lukešová, Alena; Hrčková, Kristýna; Sýkorová, Eva


    Telomerase maintains the ends of eukaryotic chromosomes, and its activity is an important parameter correlating with the proliferative capacity of cells. We have investigated cell cycle-specific changes in telomerase activity using cultures of Desmodesmus quadricauda, a model alga naturally synchronized by light/dark entrainment. A quantitative telomerase assay revealed high activity in algal cultures, with slight changes during the light period. Significantly increased telomerase activity was observed at the end of the dark phase, when cell division was complete. In contrast to other models, a natural separation between nuclear and cellular division typical for the cell cycle in D. quadricauda made this observation possible.

  12. GaAsP solar cells on GaP/Si with low threading dislocation density

    Yaung, Kevin Nay; Vaisman, Michelle; Lang, Jordan; Lee, Minjoo Larry


    GaAsP on Si tandem cells represent a promising path towards achieving high efficiency while leveraging the Si solar knowledge base and low-cost infrastructure. However, dislocation densities exceeding 108 cm-2 in GaAsP cells on Si have historically hampered the efficiency of such approaches. Here, we report the achievement of low threading dislocation density values of 4.0-4.6 × 106 cm-2 in GaAsP solar cells on GaP/Si, comparable with more established metamorphic solar cells on GaAs. Our GaAsP solar cells on GaP/Si exhibit high open-circuit voltage and quantum efficiency, allowing them to significantly surpass the power conversion efficiency of previous devices. The results in this work show a realistic path towards dual-junction GaAsP on Si cells with efficiencies exceeding 30%.

  13. A Maximum Margin Learning Machine Based on Entropy Concept and Kernel Density Estimation%基于熵理论和核密度估计的最大间隔学习机

    刘忠宝; 王士同


    In order to circumvent the deficiencies of Support Vector Machine (SVM) and its improved algorithms, this paper presents Maximum-margin Learning Machine based on Entropy concept and Kernel density estimation (MLMEK). In MLMEK, data distributions in samples are represented by kernel density estimation and classification uncertainties are represented by entropy. MLMEK takes boundary data between classes and inner data in each class seriously, so it performs better than traditional SVM. MLMEK can work for two-class and one-class pattern classification. Experimental results obtained from UCI data sets verify that the algorithms proposed in the paper is effective and competitive.%该文针对支持向量机(SVM)及其变种的不足,提出一种基于熵理论和核密度估计的最大间隔学习机MLMEK.MLMEK引入了核密度估计和熵的概念,用核密度估计表征样本数据的分布特征,用熵表征分类的不确定性.MLMEK真实反映样本数据的分布特征;同时解决两类分类问题和单类分类问题;比传统SVM具有更好的分类性能.UCI数据集上的实验验证了MLMEK的有效性.

  14. Lower Salinomycin Concentration Increases Apoptotic Detachment in High-Density Cancer Cells

    Sungpil Yoon


    Full Text Available The present study identified a novel salinomycin (Sal sensitization mechanism in cancer. We tested whether Sal reduced proliferation in a high-density population by counting attached cell numbers after Sal treatment. Sal reduced proliferation in high-density cell populations. Longer exposure to Sal further reduced proliferation. Sal concentrations of 0.1 and 5 μM had similar sensitization effects, suggesting that Sal toxicity was minimal with longer exposure to a high-density cell population. The results suggest that Sal can be applied at a relatively low concentration for a longer time to overcome drug-resistant solid tumors. The 0.5 μM Sal treatment resulted in fewer attached cells than that of the 5 μM Sal treatment with a longer exposure. The lower Sal concentration mainly increased the number of easily detachable cells on the surface. In particular, 0.5 μM Sal increased cellular detachment of newly produced daughter cells. The easily-detachable cells were undergoing apoptosis. It seems that the 0.5 μM Sal treatment also increased cellular toxicity. These novel findings may contribute to the development of Sal-based therapy for patients with drug-resistant cancer or a high-density solid tumor.

  15. Hepatitis C virus coinfection does not influence the CD4 cell recovery in HIV-1-infected patients with maximum virologic suppression

    Peters, Lars; Mocroft, Amanda; Soriano, Vincent;


    BACKGROUND: Conflicting data exist whether hepatitis C virus (HCV) affects the CD4 cell recovery in patients with HIV starting antiretroviral treatment. OBJECTIVE: To investigate the influence of HCV coinfection on the CD4 recovery in patients with maximum virologic suppression within the Euro......SIDA cohort. METHODS: Patients tested for anti-HCV antibodies and with at least 2 consecutive HIV viral loads (VLs)...

  16. Microfluidic Adaptation of Density-Gradient Centrifugation for Isolation of Particles and Cells

    Yuxi Sun


    Full Text Available Density-gradient centrifugation is a label-free approach that has been extensively used for cell separations. Though elegant, this process is time-consuming (>30 min, subjects cells to high levels of stress (>350 g and relies on user skill to enable fractionation of cells that layer as a narrow band between the density-gradient medium and platelet-rich plasma. We hypothesized that microfluidic adaptation of this technique could transform this process into a rapid fractionation approach where samples are separated in a continuous fashion while being exposed to lower levels of stress (<100 g for shorter durations of time (<3 min. To demonstrate proof-of-concept, we designed a microfluidic density-gradient centrifugation device and constructed a setup to introduce samples and medium like Ficoll in a continuous, pump-less fashion where cells and particles can be exposed to centrifugal force and separated via different outlets. Proof-of-concept studies using binary mixtures of low-density polystyrene beads (1.02 g/cm3 and high-density silicon dioxide beads (2.2 g/cm3 with Ficoll–Paque (1.06 g/cm3 show that separation is indeed feasible with >99% separation efficiency suggesting that this approach can be further adapted for separation of cells.

  17. Modelling and simulation of double chamber microbial fuel cell. Cell voltage, power density and temperature variation with process parameters

    Shankar, Ravi; Mondal, Prasenjit; Chand, Shri [Indian Institute of Technology Roorkee, Uttaranchal (India). Dept. of Chemical Engineering


    In the present paper steady state models of a double chamber glucose glutamic acid microbial fuel cell (GGA-MFC) under continuous operation have been developed and solved using Matlab 2007 software. The experimental data reported in a recent literature has been used for the validation of the models. The present models give prediction on the cell voltage and cell power density with 19-44% errors, which is less (up to 20%) than the errors on the prediction of cell voltage made in some recent literature for the same MFC where the effects of the difference in pH and ionic conductivity between anodic and cathodic solutions on cell voltage were not incorporated in model equations. It also describes the changes in anodic and cathodic chamber temperature due to the increase in substrate concentration and cell current density. Temperature profile across the membrane thickness has also been studied. (orig.)

  18. High-density polymer microarrays: identifying synthetic polymers that control human embryonic stem cell growth.

    Hansen, Anne; Mjoseng, Heidi K; Zhang, Rong; Kalloudis, Michail; Koutsos, Vasileios; de Sousa, Paul A; Bradley, Mark


    The fabrication of high-density polymer microarray is described, allowing the simultaneous and efficient evaluation of more than 7000 different polymers in a single-cellular-based screen. These high-density polymer arrays are applied in the search for synthetic substrates for hESCs culture. Up-scaling of the identified hit polymers enables long-term cellular cultivation and promoted successful stem-cell maintenance. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. High cell density fed-batch fermentations for lipase production: feeding strategies and oxygen transfer.

    Salehmin, M N I; Annuar, M S M; Chisti, Y


    This review is focused on the production of microbial lipases by high cell density fermentation. Lipases are among the most widely used of the enzyme catalysts. Although lipases are produced by animals and plants, industrial lipases are sourced almost exclusively from microorganisms. Many of the commercial lipases are produced using recombinant species. Microbial lipases are mostly produced by batch and fed-batch fermentation. Lipases are generally secreted by the cell into the extracellular environment. Thus, a crude preparation of lipases can be obtained by removing the microbial cells from the fermentation broth. This crude cell-free broth may be further concentrated and used as is, or lipases may be purified from it to various levels. For many large volume applications, lipases must be produced at extremely low cost. High cell density fermentation is a promising method for low-cost production: it allows a high concentration of the biomass and the enzyme to be attained rapidly and this eases the downstream recovery of the enzyme. High density fermentation enhances enzyme productivity compared with the traditional submerged culture batch fermentation. In production of enzymes, a high cell density is generally achieved through fed-batch operation, not through perfusion culture which is cumbersome. The feeding strategies used in fed-batch fermentations for producing lipases and the implications of these strategies are discussed. Most lipase-producing microbial fermentations require oxygen. Oxygen transfer in such fermentations is discussed.

  20. Microstructure characterisation of solid oxide electrolysis cells operated at high current density

    Bowen, Jacob R.; Bentzen, Janet Jonna; Chen, Ming;

    High temperature solid oxide cells can be operated either as fuel cells or electrolysis cells for efficient power generation or production of hydrogen from steam or synthesis gas (H2 + CO) from steam and CO2 respectively. When operated under harsh conditions, they often exhibit microstructural......, microstructure evolution of the Ni-yttria stabilized zirconia (YSZ) is followed as a function of galvanostatic steam electrolysis testing at current densities between -0.5 and -1.0 A cm-2 for periods of up to 750 hours at 800 °C. The volume fraction and size of the percolating Ni particles was statistically...... quantified using the mean linear intercept method as a function of current density and correlated to increases in serial resistance. The above structural changes are then compared in terms of electrode degradation observed during the co-electrolysis of steam and CO2 at current densities up to -1.5 A cm-2...


    肖成祖; 黄子才; 刘凤云; 郭志霞; 高丽华


    Genetically-enginecred CHO cell lines,rβ-13and CLF-8B2,were cultivated with the MC-1 microcarrier cul-ture system.The cell density could be enhanced by increasing the concentration of microcarrier.At a microcarrier concentration of 10 mg/ml.the cell density could reach 4 to 5×106 cells/ml.It was shown that these cell itnes would spontaneously release from the microcarrier to attach to and proliferate on fresh microcatriera.We were thus able to scale up cultivation using a simple methcd, adding fresh mlcrocarriers and medium directiy in-to the culture system to about 2,4 or 8 times the original volume.Using a 2 L bioreactor for several weeks at medium perfusion rates of 0.5 to 3working volumes.Prourokinase was stably secreted.

  2. Very high cell density perfusion of CHO cells anchored in a non-woven matrix-based bioreactor.

    Zhang, Ye; Stobbe, Per; Silvander, Christian Orrego; Chotteau, Véronique


    Recombinant Chinese Hamster Ovary (CHO) cells producing IgG monoclonal antibody were cultivated in a novel perfusion culture system CellTank, integrating the bioreactor and the cell retention function. In this system, the cells were harbored in a non-woven polyester matrix perfused by the culture medium and immersed in a reservoir. Although adapted to suspension, the CHO cells stayed entrapped in the matrix. The cell-free medium was efficiently circulated from the reservoir into- and through the matrix by a centrifugal pump placed at the bottom of the bioreactor resulting in highly homogenous concentrations of the nutrients and metabolites in the whole system as confirmed by measurements from different sampling locations. A real-time biomass sensor using the dielectric properties of living cells was used to measure the cell density. The performances of the CellTank were studied in three perfusion runs. A very high cell density measured as 200 pF/cm (where 1 pF/cm is equivalent to 1 × 10(6)viable cells/mL) was achieved at a perfusion rate of 10 reactor volumes per day (RV/day) in the first run. In the second run, the effect of cell growth arrest by hypothermia at temperatures lowered gradually from 37 °C to 29 °C was studied during 13 days at cell densities above 100 pF/cm. Finally a production run was performed at high cell densities, where a temperature shift to 31 °C was applied at cell density 100 pF/cm during a production period of 14 days in minimized feeding conditions. The IgG concentrations were comparable in the matrix and in the harvest line in all the runs, indicating no retention of the product of interest. The cell specific productivity was comparable or higher than in Erlenmeyer flask batch culture. During the production run, the final harvested IgG production was 35 times higher in the CellTank compared to a repeated batch culture in the same vessel volume during the same time period.

  3. Tissue non-specific alkaline phosphatase production by human dental pulp stromal cells is enhanced by high density cell culture.

    Tomlinson, Matthew J; Dennis, Caitriona; Yang, Xuebin B; Kirkham, Jennifer


    The cell surface hydrolase tissue non-specific alkaline phosphatase (TNAP) (also known as MSCA-1) is used to identify a sub-population of bone marrow stromal cells (BMSCs) with high mineralising potential and is found on subsets of cells within the dental pulp. We aim to determine whether TNAP is co-expressed by human dental pulp stromal cells (hDPSCs) alongside a range of BMSC markers, whether this is an active form of the enzyme and the effects of culture duration and cell density on its expression. Cells from primary dental pulp and culture expanded hDPSCs expressed TNAP. Subsequent analyses revealed persistent TNAP expression and co-expression with BMSC markers such as CD73 and CD90. Flow cytometry and biochemical assays showed that increased culture durations and cell densities enhanced TNAP expression by hDPSCs. Arresting the hDPSC cell cycle also increased TNAP expression. These data confirm that TNAP is co-expressed by hDPSCs together with other BMSC markers and show that cell density affects TNAP expression levels. We conclude that TNAP is a potentially useful marker for hDPSC selection especially for uses in mineralised tissue regenerative therapies.

  4. Epidermal cell density is autoregulated via a secretory peptide, EPIDERMAL PATTERNING FACTOR 2 in Arabidopsis leaves.

    Hara, Kenta; Yokoo, Toshiya; Kajita, Ryoko; Onishi, Takaaki; Yahata, Saiko; Peterson, Kylee M; Torii, Keiko U; Kakimoto, Tatsuo


    Regulation of the number of cells is critical for development of multicellular organisms. During plant epidermal development, a protodermal cell first makes a fate decision of whether or not to be the meristemoid mother cell (MMC), which undergoes asymmetric cell division forming a meristemoid and its sister cell. The MMC-derived lineage produces all stomatal guard cells and a large proportion of non-guard cells. We demonstrate that a small secretory peptide, EPIDERMAL PATTERING FACTOR 2 (EPF2), is produced by the MMC and its early descendants, and negatively regulates the density of guard and non-guard epidermal cells. Our results suggest that EPF2 inhibits cells from adopting the MMC fate in a non-cell-autonomous manner, thus limiting the number of MMCs. This feedback loop is critical for regulation of epidermal cell density. The amino acid sequence of EPF2 resembles that of EPF1, which is known to control stomatal positioning. Over-expression of EPF1 also inhibits stomatal development, but EPF1 can act only on a later developmental process than EPF2. Overexpression and promoter swapping experiments suggested that the protein functions of EPF1 and EPF2, rather than the expression patterns of the genes, are responsible for the specific functions. Although targets of EPF1 and EPF2 are different, both EPF1 and EPF2 require common putative receptor components TOO MANY MOUTHS (TMM), ERECTA (ER), ERECTA LIKE 1 (ERL1) and ERL2 in order to function.

  5. Cell damage from radiation-induced bystander effects for different cell densities simulated by a mathematical model via cellular automata

    Meireles, Sincler P. de; Santos, Adriano M.; Grynberg, Suely Epsztein, E-mail: spm@cdtn.b, E-mail: amsantos@cdtn.b, E-mail: seg@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Nunes, Maria Eugenia S., E-mail: mariaeugenia@iceb.ufop.b [Universidade Federal de Ouro Preto (UFOP), MG (Brazil)


    During recent years, there has been a shift from an approach focused entirely on DNA as the main target of ionizing radiation to a vision that considers complex signaling pathways in cells and among cells within tissues. Several newly recognized responses were classified as the so-called non-target responses in which the biological effects are not directly related to the amount of energy deposited in the DNA of cells that were traversed by radiation. In 1992 the bystander effect was described referring to a series of responses such as death, chromosomal instability or other abnormalities that occur in non-irradiated cells that came into contact with irradiated cells or medium from irradiated cells. In this work, we have developed a mathematical model via cellular automata, to quantify cell death induced by the bystander effect. The model is based on experiments with irradiated cells conditioned medium which suggests that irradiated cells secrete molecules in the medium that are capable of damaging other cells. The computational model consists of two-dimensional cellular automata which is able to simulate the transmission of bystander signals via extrinsic route and via Gap junctions. The model has been validated by experimental results in the literature. The time evolution of the effect and the dose-response curves were obtained in good accordance to them. Simulations were conducted for different values of bystander and irradiated cell densities with constant dose. From this work, we have obtained a relationship between cell density and effect. (author)

  6. Stress signaling from human mammary epithelial cells contributes to phenotypes of mammographic density.

    DeFilippis, Rosa Anna; Fordyce, Colleen; Patten, Kelley; Chang, Hang; Zhao, Jianxin; Fontenay, Gerald V; Kerlikowske, Karla; Parvin, Bahram; Tlsty, Thea D


    Telomere malfunction and other types of DNA damage induce an activin A-dependent stress response in mortal nontumorigenic human mammary epithelial cells that subsequently induces desmoplastic-like phenotypes in neighboring fibroblasts. Some characteristics of this fibroblast/stromal response, such as reduced adipocytes and increased extracellular matrix content, are observed not only in tumor tissues but also in disease-free breast tissues at high risk for developing cancer, especially high mammographic density tissues. We found that these phenotypes are induced by repression of the fatty acid translocase CD36, which is seen in desmoplastic and disease-free high mammographic density tissues. In this study, we show that epithelial cells from high mammographic density tissues have more DNA damage signaling, shorter telomeres, increased activin A secretion and an altered DNA damage response compared with epithelial cells from low mammographic density tissues. Strikingly, both telomere malfunction and activin A expression in epithelial cells can repress CD36 expression in adjacent fibroblasts. These results provide new insights into how high mammographic density arises and why it is associated with breast cancer risk, with implications for the definition of novel invention targets (e.g., activin A and CD36) to prevent breast cancer.

  7. Fumed Silica Nanoparticles Incorporated in Quaternized Poly(Vinyl Alcohol Nanocomposite Membrane for Enhanced Power Densities in Direct Alcohol Alkaline Fuel Cells

    Selvaraj Rajesh Kumar


    Full Text Available A nanocomposite polymer membrane based on quaternized poly(vinyl alcohol/fumed silica (QPVA/FS was prepared via a quaternization process and solution casting method. The physico-chemical properties of the QPVA/FS membrane were investigated. Its high ionic conductivity was found to depend greatly on the concentration of fumed silica in the QPVA matrix. A maximum conductivity of 3.50 × 10−2 S/cm was obtained for QPVA/5%FS at 60 °C when it was doped with 6 M KOH. The permeabilities of methanol and ethanol were reduced with increasing fumed silica content. Cell voltage and peak power density were analyzed as functions of fumed silica concentration, temperature, methanol and ethanol concentrations. A maximum power density of 96.8 mW/cm2 was achieved with QPVA/5%FS electrolyte using 2 M methanol + 6 M KOH as fuel at 80 °C. A peak power density of 79 mW/cm2 was obtained using the QPVA/5%FS electrolyte with 3 M ethanol + 5 M KOH as fuel. The resulting peak power densities are higher than the majority of published reports. The results confirm that QPVA/FS exhibits promise as a future polymeric electrolyte for use in direct alkaline alcoholic fuel cells.

  8. Density of states measurements in a p-i-n solar cell

    Crandall, R.S.; Wang, Q. [National Renewable Energy Lab., Golden, CO (United States)


    The authors describe results of density of states (DOS) profiling in p-i-n solar-cell devices using drive-level capacitance (DLC) techniques. Near the p-i interface the defect density is high, decreasing rapidly into the interior, reaching low values in the central region of the cell, and rising rapidly again at the n-i interface. They show that the states in the central region are neutral dangling-bond defects, whereas those near the interfaces with the doped layers are charged dangling bonds.

  9. LTE Micro-cell Deployment for High-Density Railway Areas

    Sniady, Aleksander; Kassab, Mohamed; Soler, José


    Long Term Evolution (LTE) is a serious candidate for the future releases of the European Rail Traffic Management System (ERTMS). LTE offers more capacity and supports new communication-based applications and services for railways. Nevertheless, even with this technology, the classical macro......-cell radio deployments reach overload, especially in high-density areas, such as major train stations. In this paper, an LTE micro-cell deployment is investigated in high-density railway areas. Copenhagen Main Station is considered as a realistic deployment study case, with a set of relevant railway...

  10. Cell-Autonomous Regulation of Dendritic Spine Density by PirB


    Synapse density on cortical pyramidal neurons is modulated by experience. This process is highest during developmental critical periods, when mechanisms of synaptic plasticity are fully engaged. In mouse visual cortex, the critical period for ocular dominance (OD) plasticity coincides with the developmental pruning of synapses. At this time, mice lacking paired Ig-like receptor B (PirB) have excess numbers of dendritic spines on L5 neurons; these spines persist and are thought to underlie the juvenile-like OD plasticity observed in adulthood. Here we examine whether PirB is required specifically in excitatory neurons to exert its effect on dendritic spine and synapse density during the critical period. In mice with a conditional allele of PirB (PirBfl/fl), PirB was deleted only from L2/3 cortical pyramidal neurons in vivo by timed in utero electroporation of Cre recombinase. Sparse mosaic expression of Cre produced neurons lacking PirB in a sea of wild-type neurons and glia. These neurons had significantly elevated dendritic spine density, as well as increased frequency of miniature EPSCs, suggesting that they receive a greater number of synaptic inputs relative to Cre– neighbors. The effect of cell-specific PirB deletion on dendritic spine density was not accompanied by changes in dendritic branching complexity or axonal bouton density. Together, results imply a neuron-specific, cell-autonomous action of PirB on synaptic density in L2/3 pyramidal cells of visual cortex. Moreover, they are consistent with the idea that PirB functions normally to corepress spine density and synaptic plasticity, thereby maintaining headroom for cells to encode ongoing experience-dependent structural change throughout life.

  11. Increased apoptosis and decreased density of medial smooth muscle cells in human abdominal aortic aneurysms

    ZHANG Jian张健; Jan Schmidt; Eduard Ryschich; Hardy Schumacher; Jens R Allenberg


    Objective To determine the increase of apoptosis and the decrease of smooth muscle cells (SMCs) density in human abdominal aortic aneurysms (AAA). Methods In situ terminal transferase-mediated dUTP nick end labeling (TUNEL) was employed to detect apoptosis of SMCs in patients with AAA (n=25) and normal abdominal aortae (n=10). Positive cells were identified by specific cell marker in combination with immunohistochemistry. Meanwhile SMC counting was performed by anti-α-actin immunohistostaining to compare the SMC density. Results TUNEL staining revealed that there was significantly increased apoptosis in AAAs (average 8.6%) compared with normal abdominal aortae (average 0.95%, P<0.01). Double staining showed that most of these cells were SMCs. Counting of α-actin positive SMCs revealed that medial SMC density of AAAs (37.5±7.6 SMCs /HPF) was reduced by 79.1% in comparison with that of normal abdominal aortae (179.2±16.1 SMCs /HPF, P<0.01). Conclusions Significantly increased SMCs of AAA bear apoptotic markers initiating cell death. Elevated apoptosis may result in a decreased density of SMCs in AAA, which may profoundly influence the development of AAA.

  12. Experimental characterization of active acoustic metamaterial cell with controllable dynamic density

    Akl, Wael; Baz, Amr


    Controlling wave propagation pattern within acoustic fluid domains has been the motivation for the acoustic metamaterials developments to target applications ranging from acoustic cloaking to passive noise control techniques. Currently, various numerical and analytical approaches exist to predict the fluid domain material properties necessary for specific propagation pattern. Physical attempts to realize such material properties have revealed engineered material constructions that are focused on predefined wave propagation patterns. In the current paper, coupled fluid-structure one-dimensional metamaterial cell, in which piezoelectric active ingredient has been introduced, is manufactured to achieve controllable dynamic density. The density-controllable cell has been manufactured by coupling a water-filled cavity with piezoelectric elements in a cell of 4.5 cm length and 4.1 cm diameter subject to impulse excitation. A finite element model of the cell has been developed and its predictions are validated against the experimental results. The validated model is utilized to predict the changes in the pressure gradient inside the developed cell which is a direct measure of the changes introduced to the dynamic density of the acoustic metamaterial domain. With such predictions, it is demonstrated that densities as high as 3.2 gm/cm3 and as low as 0.72 gm/cm3 can be achieved experimentally for excitation frequencies ranging between 100 Hz and 500 Hz.

  13. The influence of neuronal density and maturation on network activity of hippocampal cell cultures: a methodological study

    Biffi, Emilia; Regalia, Giulia; Menegon, Andrea; Ferrigno, Giancarlo; Pedrocchi, Alessandra


    .... Neuronal cultures plated with different cell densities differ in number of synapses per neuron and thus in single neuron synaptic transmission, which results in a density-dependent neuronal network activity...

  14. High cell density cultivations by alternating tangential flow (ATF) perfusion for influenza A virus production using suspension cells.

    Genzel, Yvonne; Vogel, Thomas; Buck, Johannes; Behrendt, Ilona; Ramirez, Daniel Vazquez; Schiedner, Gudrun; Jordan, Ingo; Reichl, Udo


    High cell densities in animal cell culture can be obtained by continuous perfusion of fresh culture medium across hollow fiber membranes that retain the cells. Careful selection of the membrane type and cut-off allows to control accumulation of target molecules and removal of low molecular weight compounds. In this report, perfusion with the scalable ATF (alternating tangential filtration, Refine Technology) system was evaluated for two suspension cell lines, the avian cell line AGE1.CR and the human cell line CAP. Both were cultivated in chemically defined media optimized for batch cell growth in a 1L stirred tank bioreactor connected to the smallest ATF unit (ATF2) and infected with cell line-adapted human influenza A virus (A/PR/8/34 (H1N1), typical diameter: 80-100 nm). At concentrations of about 25 million cells/mL three different membrane cut-offs (50 kDa, 0.2 μm and 0.5 μm) were tested and compared to batch cultivations performed at 5 million cells/mL. For medium and large cut-offs no cell-density effect could be observed with cell-specific virus yields of 1428-1708 virions/AGE1.CR cell (infected with moi 0.001) and 1883-4086 virions/CAP cell (moi of 0.025) compared to 1292 virions/AGE1.CR cell and 3883 virions/CAP cell in batch cultures. Even at a concentration of 48 million AGE1.CR cells/mL (cut-off: 0.2 μm) a cell-specific yield of 1266 virions/cell was reached. Only for the small cut-off (50 kDa) used with AGE1.CR cells a decrease in cell-specific yield was measured with 518 virions/cell. Surprisingly, the ratio of infectious to total virions seemed to be increased in ATF compared to batch cultures. AGE1.CR cell-derived virus particles were present in the permeate (0.2 and 0.5 μm cut-off), whereas CAP cell-derived virions were not, suggesting possible differences in morphology, aggregation or membrane properties of the virions released by the two cell lines. To our knowledge, this is the first study that illustrates the potential of ATF


    Professor Anil V. Virkar


    This report summarizes the work done during the entire project period, between October 1, 1999 and March 31, 2003, which includes a six-month no-cost extension. During the project, eight research papers have, either been, published, accepted for publication, or submitted for publication. In addition, several presentations have been made in technical meetings and workshops. The project also has provided support for four graduate students working towards advanced degrees. The principal technical objective of the project was to analyze the role of electrode microstructure on solid oxide fuel cell performance. Prior theoretical work conducted in our laboratory demonstrated that the particle size of composite electrodes has a profound effect on cell performance; the finer the particle size, the lower the activation polarization, the better the performance. The composite cathodes examined consisted of electronically conducting perovskites such as Sr-doped LaMnO{sub 3} (LSM) or Sr-doped LaCoO{sub 3} (LSC), which is also a mixed conductor, as the electrocatalyst, and yttria-stabilized zirconia (YSZ) or rare earth oxide doped CeO{sub 2} as the ionic conductor. The composite anodes examined were mixtures of Ni and YSZ. A procedure was developed for the synthesis of nanosize YSZ by molecular decomposition, in which unwanted species were removed by leaching, leaving behind nanosize YSZ. Anode-supported cells were made using the as-synthesized powders, or using commercially acquired powders. The electrolyte was usually a thin ({approx}10 microns), dense layer of YSZ, supported on a thick ({approx}1 mm), porous Ni + YSZ anode. The cathode was a porous mixture of electrocatalyst and an ionic conductor. Most of the cell testing was done at 800 C with hydrogen as fuel and air as the oxidant. Maximum power densities as high as 1.8 W/cm{sup 2} were demonstrated. Polarization behavior of the cells was theoretically analyzed. A limited amount of cell testing was done using liquid

  16. Hybrid Solid Oxide Fuel Cell and Thermoelectric Generator for Maximum Power Output in Micro-CHP Systems

    Rosendahl, Lasse; Mortensen, Paw Vestergård; Enkeshafi, Ali A.


    and market segments which are not yet quantified. This paper quantifies a micro-CHP system based on a solid oxide fuel cell (SOFC) and a high-performance TE generator. Based on a 3 kW fuel input, the hybrid SOFC implementation boosts electrical output from 945 W to 1085 W, with 1794 W available for heating......One of the most obvious early market applications for thermoelectric generators (TEG) is decentralized micro combined heat and power (CHP) installations of 0.5 kWe to 5 kWe based on fuel cell technology. Through the use of TEG technology for waste heat recovery it is possible to increase...... the electricity production in micro-CHP systems by more than 15%, corresponding to system electrical efficiency increases of some 4 to 5 percentage points. This will make fuel cell-based micro-CHP systems very competitive and profitable and will also open opportunities in a number of other potential business...

  17. Hybrid Solid Oxide Fuel Cell and Thermoelectric Generator for Maximum Power Output in Micro-CHP Systems

    Rosendahl, L. A.; Mortensen, Paw V.; Enkeshafi, Ali A.


    One of the most obvious early market applications for thermoelectric generators (TEG) is decentralized micro combined heat and power (CHP) installations of 0.5 kWe to 5 kWe based on fuel cell technology. Through the use of TEG technology for waste heat recovery it is possible to increase the electricity production in micro-CHP systems by more than 15%, corresponding to system electrical efficiency increases of some 4 to 5 percentage points. This will make fuel cell-based micro-CHP systems very competitive and profitable and will also open opportunities in a number of other potential business and market segments which are not yet quantified. This paper quantifies a micro-CHP system based on a solid oxide fuel cell (SOFC) and a high-performance TE generator. Based on a 3 kW fuel input, the hybrid SOFC implementation boosts electrical output from 945 W to 1085 W, with 1794 W available for heating purposes.

  18. The effect of cell size and channel density on neuronal information encoding and energy efficiency.

    Sengupta, Biswa; Faisal, A Aldo; Laughlin, Simon B; Niven, Jeremy E


    Identifying the determinants of neuronal energy consumption and their relationship to information coding is critical to understanding neuronal function and evolution. Three of the main determinants are cell size, ion channel density, and stimulus statistics. Here we investigate their impact on neuronal energy consumption and information coding by comparing single-compartment spiking neuron models of different sizes with different densities of stochastic voltage-gated Na(+) and K(+) channels and different statistics of synaptic inputs. The largest compartments have the highest information rates but the lowest energy efficiency for a given voltage-gated ion channel density, and the highest signaling efficiency (bits spike(-1)) for a given firing rate. For a given cell size, our models revealed that the ion channel density that maximizes energy efficiency is lower than that maximizing information rate. Low rates of small synaptic inputs improve energy efficiency but the highest information rates occur with higher rates and larger inputs. These relationships produce a Law of Diminishing Returns that penalizes costly excess information coding capacity, promoting the reduction of cell size, channel density, and input stimuli to the minimum possible, suggesting that the trade-off between energy and information has influenced all aspects of neuronal anatomy and physiology.

  19. Enzyme controlled glucose auto-delivery for high cell density cultivations in microplates and shake flasks

    Casteleijn Marco G


    Full Text Available Abstract Background Here we describe a novel cultivation method, called EnBase™, or enzyme-based-substrate-delivery, for the growth of microorganisms in millilitre and sub-millilitre scale which yields 5 to 20 times higher cell densities compared to standard methods. The novel method can be directly applied in microwell plates and shake flasks without any requirements for additional sensors or liquid supply systems. EnBase is therefore readily applicable for many high throughput applications, such as DNA production for genome sequencing, optimisation of protein expression, production of proteins for structural genomics, bioprocess development, and screening of enzyme and metagenomic libraries. Results High cell densities with EnBase are obtained by applying the concept of glucose-limited fed-batch cultivation which is commonly used in industrial processes. The major difference of the novel method is that no external glucose feed is required, but glucose is released into the growth medium by enzymatic degradation of starch. To cope with the high levels of starch necessary for high cell density cultivation, starch is supplied to the growing culture suspension by continuous diffusion from a storage gel. Our results show that the controlled enzyme-based supply of glucose allows a glucose-limited growth to high cell densities of OD600 = 20 to 30 (corresponding to 6 to 9 g l-1 cell dry weight without the external feed of additional compounds in shake flasks and 96-well plates. The final cell density can be further increased by addition of extra nitrogen during the cultivation. Production of a heterologous triosphosphate isomerase in E. coli BL21(DE3 resulted in 10 times higher volumetric product yield and a higher ratio of soluble to insoluble product when compared to the conventional production method. Conclusion The novel EnBase method is robust and simple-to-apply for high cell density cultivation in shake flasks and microwell plates. The

  20. A mathematical model of the current density distribution in electrochemical cells - AUTHORS’ REVIEW



    Full Text Available An approach based on the equations of electrochemical kinetics for the estimation of the current density distribution in electrochemical cells is presented. This approach was employed for a theoretical explanation of the phenomena of the edge and corner effects. The effects of the geometry of the system, the kinetic parameters of the cathode reactions and the resistivity of the solution are also discussed. A procedure for a complete analysis of the current distribution in electrochemical cells is presented.

  1. Absolute choline concentration measured by quantitative proton MR spectroscopy correlates with cell density in meningioma

    Yue, Qiang [University of Tsukuba, Department of Neurosurgery, Institute of Clinical Medicine, Tsukuba Science City, Ibaraki (Japan)]|[West China Hospital of Sichuan University, Huaxi MR Research Center, Department of Radiology, Chengdu (China); Shibata, Yasushi; Kawamura, Hiraku; Matsumura, Akira [University of Tsukuba, Department of Neurosurgery, Institute of Clinical Medicine, Tsukuba Science City, Ibaraki (Japan); Isobe, Tomonori [Kitasato University, Department of Medical Technology, School of Allied Health Sciences, Minato, Tokyo (Japan); Anno, Izumi [University of Tsukuba, Department of Radiology, Institute of Clinical Medicine, Tsukuba, Ibaraki (Japan); Gong, Qi-Yong [West China Hospital of Sichuan University, Huaxi MR Research Center, Department of Radiology, Chengdu (China)]|[University of Liverpool, Division of Medical Imaging, Faculty of Medicine, Liverpool (United Kingdom)


    This study was aimed to investigate the relationship between quantitative proton magnetic resonance spectroscopy (1H-MRS) and pathological changes in meningioma. Twenty-two meningioma cases underwent single voxel 1H-MRS (point-resolved spectroscopy sequence, repetition time/echo time = 2,000 ms/68, 136, 272 ms). Absolute choline (Cho) concentration was calculated using tissue water as the internal reference and corrected according to intra-voxel cystic/necrotic parts. Pathological specimens were stained with MIB-1 antibody to measure cell density and proliferation index. Correlation analysis was performed between absolute Cho concentration and cell density and MIB-1 labeled proliferation index. Average Cho concentration of all meningiomas before correction was 2.95 {+-} 0.86 mmol/kg wet weight. It was increased to 3.23 {+-} 1.15 mmol/kg wet weight after correction. Average cell density of all meningiomas was 333 {+-} 119 cells/HPF, and average proliferation index was 2.93 {+-} 5.72%. A linear, positive correlation between cell density and Cho concentration was observed (r = 0.650, P = 0.001). After correction of Cho concentration, the correlation became more significant (r = 0.737, P < 0.001). However, no significant correlation between Cho concentration and proliferation index was found. There seemed to be a positive correlation trend after correction of Cho concentration but did not reach significant level. Absolute Cho concentration, especially Cho concentration corrected according to intra-voxel cystic/necrotic parts, reflects cell density of meningioma. (orig.)

  2. A method for the design of 3D scaffolds for high-density cell attachment and determination of optimum perfusion culture conditions.

    Provin, Christophe; Takano, Kiyoshi; Sakai, Yasuyuki; Fujii, Teruo; Shirakashi, Ryo


    The application of in vitro cultured cells in tissue engineering or drug screening, aimed at complex soft tissues such as liver, requires in vivo physiological function of the cultured cells. For this purpose, the scaffold in which cells are cultured should provide a microenvironment similar to an in vivo one with a three-dimensional extracellular matrix, a high supply capacity of O(2) and nutrients, and high cell density. In this paper, we propose a method to design (1) the geometry of the scaffold, with a surface/volume ratio optimized to allow high-density (5 x 10(7)cells/mL) cell culture and (2) culture conditions that will supply optimal quantities of oxygen and nutrients. CFD modeling of mass transport was used to determine the shear stress as well as O(2) and glucose metabolism in the scaffold (20 mm width-35 mm length) for various flow rates. Validation of the model was done through comparison with flow resistance and micro-PIV experiments. CFD analysis showed the maximum metabolic rate densities for this scaffold are 6.04 x 10(-3)mol/s/m(3) for O(2) at 0.71 mL/min and 1.91 x 10(-2)mol/s/m(3) for glucose at 0.35 mL/min.

  3. Ultra-high cell-density silicon photomultipliers with high detection efficiency

    Acerbi, Fabio; Gola, Alberto; Regazzoni, Veronica; Paternoster, Giovanni; Borghi, Giacomo; Piemonte, Claudio; Zorzi, Nicola


    Silicon photomultipliers (SiPMs) are arrays of many single-photon avalanche diodes (SPADs), all connected in parallel. Each SPAD is sensitive to single photons and the SiPM gives an output proportional to the number of detected photons. These sensors are becoming more and more popular in different applications, from high-energy physics to spectroscopy, and they have been significantly improved over last years, decreasing the noise, increasing the cell fill-factor (FF) and thus achieving very high photon-detection efficiency (PDE). In FBK (Trento, Italy), we developed new SiPM technologies with high-density (HD) and, more recently, ultra-high-density (UHD) of cells (i.e. density of SPADs). These technologies employ deep-trenches between cells, for electrical and optical isolation. As an extreme case the smallest-cell, SiPM, i.e. with 5μm cell pitch, has about 40000 SPADs per squared millimeter. Such small SPAD dimensions gives a significantly high dynamic range to the SiPM. These small-cells SiPM have a lower correlated noise (including lower afterpulsing probability) and a faster recharge time (in the order of few nanoseconds), and they also preserve a very good detection efficiency (despite the small SPAD dimension).

  4. Accurate assessment of cell density in low cellular liquid-based cervical cytology

    Siebers, A.G.; Laak, J.A.W.M. van der; Huberts-Manders, R.; Vedder, J.E.M.; Bulten, J.


    A. G. Siebers, J. A. W. M. van der Laak, R. Huberts-Manders, J. E. M. Vedder and J. Bulten Accurate assessment of cell density in low cellular liquid-based cervical cytology Objective: Scant cellularity is the most important source of unsatisfactory liquid-based cytology. Although still being debate

  5. Accurate assessment of cell density in low cellular liquid-based cervical cytology

    Siebers, A.G.; Laak, J.A.W.M. van der; Huberts-Manders, R.; Vedder, J.E.M.; Bulten, J.


    A. G. Siebers, J. A. W. M. van der Laak, R. Huberts-Manders, J. E. M. Vedder and J. Bulten Accurate assessment of cell density in low cellular liquid-based cervical cytology Objective: Scant cellularity is the most important source of unsatisfactory liquid-based cytology. Although still being debate

  6. Role of initial cell density of algal bioassay of toxic chemicals.

    Singh, Prashant Kumar; Shrivastava, Alok Kumar


    A variety of toxicants such as, metal ions, pesticides, dyes, etc. are continuously being introduced anthropogenically in the environment and adversely affect to the biotic component of the ecosystem. Therefore, the assessment of negative effects of these toxicants is required. However, toxicity assessment anticipated by chemical analysis are extremely poor, therefore the application of the living systems for the same is an excellent approach. Concentration of toxicant as well as cell density both influenced the result of the algal toxicity assay. Here, Scenedesmus sp, a very fast growing green microalgae was selected for study the effects of initial cell densities on the toxicity of Cu(II), Cd(II), Zn(II), paraquat and 2,4-D. Results demonstrated concentration dependent decrease in biomass and specific growth rate of Scenedesmus sp. on exposure of abovesaid toxicants. Paraquat and 2,4-D emerged as extremely toxic to the test alga which reflected from the lowest EC value and very steep decline in biomass was evident with increasing concentration of paraquat and 2,4-D in the medium. Result also demonstrated that initial cell density is a very important parameter than specific growth rate for algal bioassay of various toxicants. Present study clearly illustrated that the use of smaller cell density is always recommended for assaying toxicity of chemicals in algal assays. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Dietary guidance normalizes large intestinal endocrine cell densities in patients with irritable bowel syndrome.

    Mazzawi, T; Hausken, T; Gundersen, D; El-Salhy, M


    To determine the large intestinal endocrine cell types affected following dietary guidance in patients with irritable bowel syndrome (IBS). The study included 13 IBS patients and 13 control subjects. The patients received three sessions of individualized dietary guidance. Both the control subjects and the patients were scheduled for colonoscopies at baseline and again for the patients at 3-9 months after dietary guidance. Biopsy samples were taken from the colon and rectum and were immunostained for all types of large intestinal endocrine cells. The endocrine cells were quantified using computerized image analysis. The daily total consumption (mean±s.e.m. values) of fruits and vegetables rich in FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) decreased significantly from 16.2±5.3 g before receiving dietary guidance to 9.2±3.2 g after receiving dietary guidance (P=0.02). In the total colon, the densities of serotonin cells were 46.8±8.9, 10.5±2.1 and 22.6±3.2 cells/mm(2) in control subjects and in IBS patients before and after receiving dietary guidance, respectively (P=0.007); the corresponding densities of peptide YY cells were 11.6±1.8, 10.8±1.7 and 16.8±2.1 cells/mm(2), respectively (P=0.06). The cell densities for both serotonin and peptide YY did not change significantly in the rectum. The densities of somatostatin cells in the rectum were 13.5±3.0, 13.2±3.0, and 22.3±3.2 cells/mm(2) for control subjects and for IBS patients before and after receiving dietary guidance, respectively (P=0.01). The densities of the large intestinal endocrine cells tend to normalize following dietary guidance that may have contributed to the improvement of the patients with IBS symptoms.

  8. On-line near infrared bioreactor monitoring of cell density and concentrations of glucose and lactate during insect cell cultivation.

    Qiu, Jiang; Arnold, Mark A; Murhammer, David W


    Near infrared spectroscopy is demonstrated as a suitable method for monitoring real time cell density and concentrations of glucose and lactate during insect cell cultivation. The utility of this approach is illustrated during the cultivation of Trichoplusia ni BTI-Tn-5B1-4 insect cells in a stirred-tank bioreactor. On-line near infrared measurements are made by passing unaltered culture medium through an autoclavable near infrared flow-through sample cell during the cultivation process. Single-beam near infrared spectra were collected over the combination spectral range (5000-4000cm(-1)) through a 1.5mm path length sample. Cell density calibration model was established by uni-variable linear regressions with measured mean absorbance values of on-line spectra collected during a cultivation run. Calibration models are generated for glucose and lactate by regression analysis of both off line and on line spectra collected during a series of pre-measurement cultivation runs. Analyte-specific calibration models are generated by using a combination of spectra from both natural, unaltered samples and samples spiked with known levels of glucose and lactate. Spiked samples are used to destroy concentration correlations between solutes, thereby enhancing the selectivity of the calibration models. Absorbance spectra are used to build partial least squares calibration models for glucose and lactate. The calibration model for cell density corresponds to a univariate linear regression calibration model based on the mean absorbance between 4750 and 4250cm(-1). The standard errors of prediction are 1.54mM, 0.83mM, and 0.38×10(6)cells/mL for the glucose, lactate, and cell density models, respectively.

  9. Location and Density of Immune Cells in Precursor Lesions and Cervical Cancer.

    Bedoya, Astrid M; Jaramillo, Roberto; Baena, Armando; Castaño, Jorge; Olaya, Natalia; Zea, Arnold H; Herrero, Rolando; Sanchez, Gloria I


    Only a small proportion of women infected with Human Papillomavirus (HPV) develop cervical cancer. Host immune response seems to play a role eliminating the viral infection and preventing progression to cancer. Characterization of tumor infiltrating lymphocytes (TILs) in cervical pre-neoplastic lesions and cervical cancer may be helpful to understand the mechanisms that mediate this protection. The aim of this study was to determine if there are differences in the localization and density (cells/mm(2)) of CD8+ T-cells, CD4+ T-cells and Tregs (CD25 + Foxp3+) in cervical pre-neoplastic lesions and cervical cancer. Immunohistochemical analysis of sections of 96 (26 CIN1, 21 CIN2, 25 CIN3, and 24 SCC) samples revealed that regardless of CIN grades, CD8+ T-cells are more abundant than CD4+, CD25+ and Foxp3+ cells in both the stroma and epithelium. There was a higher density of CD8+ cells in the stroma of cervical cancer compared to CIN3 (OR = 4.20, 95% CI 1.2-15), CIN2 (OR = 7.86, 95% CI 1.7-36.4) and CIN1 (OR = 4.25, 95% CI 1.1-17). Studies evaluating whether these cells are recruited before or after cancer progression will be helpful to understand the role of these cells in the natural history of HPV-induced lesions.

  10. Enhancement of thermoalkaliphilic xylanase production by Pichia pastoris through novel fed-batch strategy in high cell-density fermentation

    Shang, Tingting; Si, Dayong; Zhang, Dongyan; Liu, Xuhui; Zhao, Longmei; Hu, Cong; Fu, Yu; Zhang, Rijun


    .... This study aims to enhance thermoalkaliphilic xylanase production in Pichia pastoris through fermentation parameters optimization and novel efficient fed-batch strategy in high cell-density fermentation...

  11. Noninvasive prenatal diagnosis. Use of density gradient centrifugation, magnetically activated cell sorting and in situ hybridization

    Campagnoli, C; Multhaupt, H A; Ludomirski, A;


    cells recovered did not differ. Seven of seven male pregnancies were correctly identified. One case of trisomy 21 was detected. CONCLUSION: The in situ hybridization analysis of fetal nucleated erythrocytes isolated from maternal blood using single density gradient centrifugation, anti-CD71/anti...... of the isolated cells were subjected to in situ hybridization with specific DNA probes for the Y chromosome and chromosome 21 to confirm the fetal origin. RESULTS: After MiniMACS the enrichment factors for the CD71/GPA- and CD36/GPA-positive cells from maternal blood were similar, and the percentages of fetal...

  12. A High Power-Density Mediator-Free Microfluidic Biophotovoltaic Device for Cyanobacterial Cells

    Bombelli, Paolo; Herling, Therese W; Howe, Christopher J; Knowles, Tuomas P J


    Biophotovoltaics has emerged as a promising technology for generating renewable energy since it relies on living organisms as inexpensive, self-repairing and readily available catalysts to produce electricity from an abundant resource - sunlight. The efficiency of biophotovoltaic cells, however, has remained significantly lower than that achievable through synthetic materials. Here, we devise a platform to harness the large power densities afforded by miniaturised geometries. To this effect, we have developed a soft-lithography approach for the fabrication of microfluidic biophotovoltaic devices that do not require membranes or mediators. Synechocystis sp. PCC 6803 cells were injected and allowed to settle on the anode, permitting the physical proximity between cells and electrode required for mediator-free operation. We demonstrate power densities of above 100 mW/m2 for a chlorophyll concentration of 100 {\\mu}M under white light, a high value for biophotovoltaic devices without extrinsic supply of additional...

  13. Multi-stage continuous high cell density culture systems: a review.

    Chang, Ho Nam; Jung, Kwonsu; Choi, Jin-Dal-Rae; Lee, Joon Chul; Woo, Hee-Chul


    A multi-stage continuous high cell density culture (MSC-HCDC) system makes it possible to achieve high productivity together with high product titer of many bioproducts. For long-term continuous operation of MSC-HCDC systems, the cell retention time and hydraulic retention time must be decoupled and strains (bacteria, yeast, plant, and animal cells) must be stable. MSC-HCDC systems are suitable for low-value high-volume extracellular products such as fuel ethanol, lactic acid or volatile fatty acids, and high-value products such as monoclonal antibodies as well as intracellular products such as polyhydroxybutyric acid (PHB), microbial lipids or a number of therapeutics. Better understanding of the fermentation kinetics of a specific product and reliable high-density culture methods for the product-generating microorganisms will facilitate timely industrialization of MSC-HCDC systems for products that are currently obtained in fed-batch bioreactors.

  14. Densidade e qualidade dos estratos de forragem do capim Tanzânia (Panicum maximum Jacq. Cv. Tanzânia-1 manejado em diferentes alturas, sob pastejo Density bulk and quality of Tanzania grass layers (Panicum maximum Tanzania-1, at different heights in grazing

    Geraldo Tadeu dos Santos


    Full Text Available O objetivo do trabalho foi avaliar o efeito de diferentes alturas (24; 26; 43; 45; 52; 62; 73 e 78 cm do pasto sobre a qualidade de forragem e estrutura do perfil do capim-Tanzânia, (Panicum maximum Jacq. cv. Tanzânia – 1 (Poaceae. Foram utilizados novilhos da raça Nelore sob pastejo com carga animal variável, por meio da técnica put and take. O delineamento experimental utilizado foi inteiramente casualizado, com duas repetições. A densidade de matéria seca total (DMT aumentou com o avanço no período experimental, enquanto a densidade de matéria seca de lâminas (DML não foi influenciada pelo período e pela altura do pasto. O estrato superior da pastagem foi a porção de maior qualidade, apresentando maior DML e maior teor de PB. Os estratos inferiores apresentaram menor qualidade, devido à maior DMT e menor DML, acarretando em maiores valores de FDA e FDN e menores teores de PB. O conteúdo de minerais das lâminas foi superior aos colmos, mantendo-se inalterado com relação aos estratos da pastagem.The effect of different sward heights (24; 26; 43; 45; 52; 62; 73 and 78 cm on forage quality and profile structure Tanzania grass, Panicum maximum Jacq. cv. Tanzania – 1 (Poaceae is provided. Nelore steers were used in grazing at variable stocking rates with put and take technique. The experimental design was completely randomized, with two replications. Total dry matter bulk densitity (TDMD increased during experimental period, while the leaf blade dry matter bulk density (LDMD was not influenced by period on by sward height. The upper layers had the best quality with higher LDMD and CP levels. Lower layers had the worst quality, due the higher TDMD and lower LDMD. This fact caused higher ADF and NDF levels and lower CP levels. Leaf blade mineral content was higher than that of stem, and remained unaltered in relation to the different layers.

  15. The role of oxygen in yeast metabolism during high cell density brewery fermentations.

    Verbelen, P J; Saerens, S M G; Van Mulders, S E; Delvaux, F; Delvaux, F R


    The volumetric productivity of the beer fermentation process can be increased by using a higher pitching rate (i.e., higher inoculum size). However, the decreased yeast net growth observed in these high cell density fermentations can have a negative impact on the physiological stability throughout subsequent yeast generations. The use of different oxygen conditions (wort aeration, wort oxygenation, yeast preoxygenation) was investigated to improve the growth yield during high cell density fermentations and yeast metabolic and physiological parameters were assessed systematically. Together with a higher extent of growth (dependent on the applied oxygen conditions), the fermentation power and the formation of unsaturated fatty acids were also affected. Wort oxygenation had a significant decreasing effect on the formation of esters, which was caused by a decreased expression of the alcohol acetyl transferase gene ATF1, compared with the other conditions. Lower glycogen and trehalose levels at the end of fermentation were observed in case of the high cell density fermentations with oxygenated wort and the reference fermentation. The expression levels of BAP2 (encoding the branched chain amino acid permease), ERG1 (encoding squalene epoxidase), and the stress responsive gene HSP12 were predominantly influenced by the high cell concentrations, while OLE1 (encoding the fatty acid desaturase) and the oxidative stress responsive genes SOD1 and CTT1 were mainly affected by the oxygen availability per cell. These results demonstrate that optimisation of high cell density fermentations could be achieved by improving the oxygen conditions, without drastically affecting the physiological condition of the yeast and beer quality.

  16. Quantum dot density studies for quantum dot intermediate band solar cells

    Thomassen, Sedsel Fretheim; Zhou, Dayong; Vitelli, Stefano; Mayani, Maryam Gholami; Fimland, Bjoern-Ove; Reenaas, Turid Worren


    Quantum dots (QDs) have been an active area of research for many years and have been implemented in several applications, such as lasers and detectors. During the last years, some attempts have been made to increase the absorption and efficiency of solar cells by inserting QDs into the intrinsic region of pin solar cells. So far, these attempts have been successful in increasing the absorption, but not the cell efficiency. There are probably several reasons for this lack of efficiency increase, but we believe that one important reason is the low density of the implemented QDs. In this work, samples of single layer InAs QDs on n-GaAs(001) substrates have been grown by molecular beam epitaxy (MBE) and we have performed a systematic study of how deposition parameters affect the QD density. The aim is to achieve densities > 1011 cm-2. The nominal substrate temperature (360 - 500 deg. C), the InAs growth rate (0.085 - 1 ML/s) and thickness (2.0 - 2.8 ML) have been varied in a systematic way for two different deposition methods of InAs, i.e. continuous deposition or deposition with interruptions. In addition, we have for the continuous growth samples also varied the As-flux (0.5 - 6 centre dot10-6 torr). Scanning electron microscopy (SEM) has been the main characterization method to determine quantum dot sizes and densities, and atomic force microscopy (AFM) has been used for evaluation of the quantum dot heights. We find that the QD density increases with reduced growth temperature and that it is higher for samples grown continuously than for samples grown with growth interruptions. The homogeneity is also strongly affected by temperature, InAs deposition method and the As-flux. We have observed QD densities as high as 2.5 centre dot1011 cm-2 for the samples grown at the lowest growth temperatures. (Author)

  17. The reasons for the high power density of fuel cells fabricated with directly deposited membranes

    Vierrath, Severin; Breitwieser, Matthias; Klingele, Matthias; Britton, Benjamin; Holdcroft, Steven; Zengerle, Roland; Thiele, Simon


    In a previous study, we reported that polymer electrolyte fuel cells prepared by direct membrane deposition (DMD) produced power densities in excess of 4 W/cm2. In this study, the underlying origins that give rise to these high power densities are investigated and reported. The membranes of high power, DMD-fabricated fuel cells are relatively thin (12 μm) compared to typical benchmark, commercially available membranes. Electrochemical impedance spectroscopy, at high current densities (2.2 A/cm2) reveals that mass transport resistance was half that of reference, catalyst-coated-membranes (CCM). This is attributed to an improved oxygen supply in the cathode catalyst layer by way of a reduced propensity of flooding, and which is facilitated by an enhancement in the back diffusion of water from cathode to anode through the thin directly deposited membrane. DMD-fabricated membrane-electrode-assemblies possess 50% reduction in ionic resistance (15 mΩcm2) compared to conventional CCMs, with contributions of 9 mΩcm2 for the membrane resistance and 6 mΩcm2 for the contact resistance of the membrane and catalyst layer ionomer. The improved mass transport is responsible for 90% of the increase in power density of the DMD fuel cell, while the reduced ionic resistance accounts for a 10% of the improvement.

  18. Influence of charge densities of randomly sulfonated polystyrene surfaces on cell attachment and proliferation.

    Khatua, Dibyendu; Kwak, Byeongdo; Shin, Kwanwoo; Song, Ju-Myung; Kim, Joon-Seop; Choi, Jai-Hak


    Attachment and proliferation of NIH-3T3 fibroblast cells on random polymer surfaces, polystyrene sulfonated acid (PSSAx) with five different degrees of sulfonation (x = 0%, 5%, 10%, 15% and 33%) and on a tissue culture polystyrene (TCPS) surface were studied. The surface properties, wettability and roughness were measured by water-contact angle and atomic force microscopy measurement. The wettability and surface roughness increased with increasing the content of sulfonic acid groups on the surfaces. The number of cells attached on the surface after seeding increased with increasing x and reached to the maximum value on PSSA15. The cell proliferation also increased with increasing x. However, cell proliferation was slow down on PSSA33 in comparison to PSSA10 and PSSA15 surfaces after 48 h culture.

  19. Superhydrophilic-Superhydrophobic Patterned Surfaces as High-Density Cell Microarrays: Optimization of Reverse Transfection.

    Ueda, Erica; Feng, Wenqian; Levkin, Pavel A


    High-density microarrays can screen thousands of genetic and chemical probes at once in a miniaturized and parallelized manner, and thus are a cost-effective alternative to microwell plates. Here, high-density cell microarrays are fabricated by creating superhydrophilic-superhydrophobic micropatterns in thin, nanoporous polymer substrates such that the superhydrophobic barriers confine both aqueous solutions and adherent cells within each superhydrophilic microspot. The superhydrophobic barriers confine and prevent the mixing of larger droplet volumes, and also control the spreading of droplets independent of the volume, minimizing the variability that arises due to different liquid and surface properties. Using a novel liposomal transfection reagent, ScreenFect A, the method of reverse cell transfection is optimized on the patterned substrates and several factors that affect transfection efficiency and cytotoxicity are identified. Higher levels of transfection are achieved on HOOC- versus NH2 -functionalized superhydrophilic spots, as well as when gelatin and fibronectin are added to the transfection mixture, while minimizing the amount of transfection reagent improves cell viability. Almost no diffusion of the printed transfection mixtures to the neighboring microspots is detected. Thus, superhydrophilic-superhydrophobic patterned surfaces can be used as cell microarrays and for optimizing reverse cell transfection conditions before performing further cell screenings. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Effective dielectric properties of biological cells: generalization of the spectral density function approach.

    Goncharenko, Anatoliy V; Chang, Yia-Chung


    We suggest an extension of the spectral density function approach to describe the complex dielectric response of suspensions of arbitrarily shaped particles having a thin shell, in particular, biological cells. The approach is shown to give analytical results in some simple but practically important cases. In the general case, for the 3-phase systems it reduces to determination of the spectral density function for the suspension of a certain kind. Prospects and limitations of the approach, as well as practical examples, are also considered.

  1. Analysis of charge photogeneration as a key determinant of photocurrent density in polymer: fullerene solar cells

    Clarke, Tracey M.; Shoaee, Safa; Soon, Ying W.; Durrant, James R. [Centre for Plastic Electronics, Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Ballantyne, Amy; Nelson, Jenny [Centre for Plastic Electronics, Department of Physics, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Duffy, Warren; Heeney, Martin; McCulloch, Iain [Centre for Plastic Electronics, Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Merck Chemicals, Chilworth Science Park, Southampton SO16 7QD (United Kingdom)


    Charge photogeneration: The correlation between the efficiency of photogeneration of dissociated polarons and photocurrent densities for organic solar cells based on polymer:fullerene blend films is investigated. Optical assays of polaron yield measured in films without electrodes show a remarkably clear correlation with short circuit density and quantum yield measured in complete devices. For the blend films studied herein, the primary determinant of photocurrent generation is the efficiency of dissociation of photogenerated charges away from the polymer/fullerene interface and the primary loss pathway is geminate recombination. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Low Density Lipoprotein Receptor Related Proteins as Regulators of Neural Stem and Progenitor Cell Function

    Loic Auderset


    Full Text Available The central nervous system (CNS is a highly organised structure. Many signalling systems work in concert to ensure that neural stem cells are appropriately directed to generate progenitor cells, which in turn mature into functional cell types including projection neurons, interneurons, astrocytes, and oligodendrocytes. Herein we explore the role of the low density lipoprotein (LDL receptor family, in particular family members LRP1 and LRP2, in regulating the behaviour of neural stem and progenitor cells during development and adulthood. The ability of LRP1 and LRP2 to bind a diverse and extensive range of ligands, regulate ligand endocytosis, recruit nonreceptor tyrosine kinases for direct signal transduction and signal in conjunction with other receptors, enables them to modulate many crucial neural cell functions.

  3. High densities of serotonin and peptide YY cells in the colon of patients with lymphocytic colitis

    Magdy El-Salhy; Doris Gundersen; Jan Gunnar Hatlebakk; Trygve Hausken


    AIM:To investigate colonic endocrine cells in lymphocytic colitis (LC) patients.METHODS:Fifty-seven patients with LC were included.These patients were 41 females and 16 males,with an average age of 49 years (range 19-84 years).Twenty-seven subjects that underwent colonoscopy with biopsies were used as controls.These subjects underwent colonoscopy because of gastrointestinal bleeding or health worries,where the source of bleeding was identified as haemorrhoids or angiodysplasia.They were 19 females and 8 males with an average age of 49 years (range 18-67 years).Biopsies from the right and left colon were obtained from both patients and controls during colonoscopy.Biopsies were fixed in 4% buffered paraformaldehyde,embedded in paraffin and cut into 5 μm-thick sections.The sections immunostained by the avidin-biotin-complex method for serotonin,peptide YY (PYY),pancreatic polypeptide (pP)enteroglucagon and somatostatin cells.The cell densities were quantified by computerised image analysis using Olympus software.RESULTS:The colon of both the patient and the control subjects were macroscopically normal.Histopathological examination of colon biopsies from controis revealed normal histology.All patients fulfilled the diagnosis criteria required for of LC:an increase in intraepithelial lymphocytes (> 20 lymphocytes/100 epithelial cells) and surface epithelial damage with increased lamina propria plasma cells and absent or minimal crypt architectural distribution.In the colon of both patients and control subjects,serotonin-,PYY-,PP-,enteroglucagon-and somatostatin-immunoreactive cells were primarily located in the upper part of the crypts of Lieberkühn.These cells were basket-or flask-shaped.There was no statistically significant difference between the right and left colon in controls with regards to the densities of serotonin-and PYY-immunoreactive cells (P =0.9 and 0.1,respectively).Serotonin cell density in the right colon in controls was 28.9 ± 1.8 and in LC

  4. Experimental study on natural convection of cold water near the maximum density in horizontal annulus%水平环缝内冷水自然对流换热实验

    唐经文; 王林豪; 高诚; 梁鑫俐; 李佳


    对水平环缝内冷水自然对流换热性能进行了实验研究.水平环缝宽度为6~18 mm,外壁温度维持0℃,换热温差为2~24℃.结果表明,在实验范围内,内壁面的平均表面传热系数随环缝宽度的增大而增加;当温差小于4℃或大于8℃时,平均表面传热系数随温差的增大而增大,在4~8℃范围内,随温差的增大而减小.采用逐步线性回归方法,得到了内壁传热关联式.%This paper conducts the experimental study on the natural convection characteristics of cold water near the maximum density in horizontal annulus with the fixed inner radius r_i=14 mm and different width l = 6~18 mm. The temperature at outer wall is maintained at 0 ℃, and the temperature differences between the inner and outer walls range from 2 to 24 ℃. The results show that the heat transfer coefficient at inner wall increases with the increase of the annulus width. When the temperature difference is bellow 4 ℃ or above 8 ℃, the heat transfer coefficient increases with the increase of the temperature difference. When the temperature difference is between 4 ℃ and 8 ℃, it. decreases with the increase of the temperature difference. The formula of heat transfer at inner walls is obtained by using the method of linear regression.

  5. Modeling Bubble Flow and Current Density Distribution in an Alkaline Electrolysis Cell

    Ravichandra S. Jupudi


    Full Text Available The effect of bubbles on the current density distribution over the electrodes of an alkaline electrolyzer cell is studied using a two-dimensional computational fluid dynamics model. Model includes Eulerian-Eulerian two-phase flow methodology to model the multiphase flow of Hydrogen and Oxygen with water and the behavior of each phase is accounted for using first principle. Hydrogen/Oxygen evolution, flow field and current density distribution are incorporated in the model to account for the complicated physics involved in the process. Fluent 6.2 is used to solve two-phase flow and electrochemistry is incorporated using UDF (User Defined Function feature of Fluent. Model is validated with mesh refinement study and by comparison with experimental measurements. Model is found to replicate the effect of cell voltage and inter-electrode gap (distance between the electrodes on current density accurately. Further, model is found to capture the existence of optimum cell height. The validated model is expected to be a very useful tool in the design and optimization of alkaline electrolyzer cells.

  6. Hippo signaling regulates microprocessor and links cell-density-dependent miRNA biogenesis to cancer.

    Mori, Masaki; Triboulet, Robinson; Mohseni, Morvarid; Schlegelmilch, Karin; Shrestha, Kriti; Camargo, Fernando D; Gregory, Richard I


    Global downregulation of microRNAs (miRNAs) is commonly observed in human cancers and can have a causative role in tumorigenesis. The mechanisms responsible for this phenomenon remain poorly understood. Here, we show that YAP, the downstream target of the tumor-suppressive Hippo-signaling pathway regulates miRNA biogenesis in a cell-density-dependent manner. At low cell density, nuclear YAP binds and sequesters p72 (DDX17), a regulatory component of the miRNA-processing machinery. At high cell density, Hippo-mediated cytoplasmic retention of YAP facilitates p72 association with Microprocessor and binding to a specific sequence motif in pri-miRNAs. Inactivation of the Hippo pathway or expression of constitutively active YAP causes widespread miRNA suppression in cells and tumors and a corresponding posttranscriptional induction of MYC expression. Thus, the Hippo pathway links contact-inhibition regulation to miRNA biogenesis and may be responsible for the widespread miRNA repression observed in cancer.

  7. Cell density and solvent are critical parameters affecting formazan evaluation in MTT assay

    Kellen Cristina da Silva Gasque


    Full Text Available The aim of this study was to establish the more accurate protocol for fibroblast cell viability using MTT assay. NIH/3T3 fibroblasts were seeded at the following cell densities: 3.125x10³; 1.156x10(4; 3.125x10(4; 1.156x10(5 and 3.125x10(5 cells/cm². Following 24h of seeding, MTT was added to the wells. After 4h of the MTT addition, different solvents were added to solubilize the formazan crystals: 1 HCl/SDS group- 20% SDS and 0.01 M HCl; 2 EtOH/ HAc group-50% ethanol and 1% acetic acid; 3 DMSO group- 99.5% dimethyl sulfoxide; and 4 PropOH group- 99.5% isopropanol. The absorbance values were measured using a spectrophotometer at 570 nm. The data were analyzed by 2-way ANOVA (p<0.05 and showed that the absorbance average varied according to the number of cells and solvents: HCl/SDS (0 to 0.13, EtOH/HAc (0 to 0.22, DMSO (0.76 to 1.31 and PropOH (0.66 to 1.04. The DMSO and PropOH groups presented the most appropriate protocols for NIH/3T3 fibroblasts cell viability, especially at the density of 1.156x10(4 cells/cm².

  8. Measurement of Single Cell Refractive Index, Dry Mass, Volume, and Density Using a Transillumination Microscope

    Phillips, Kevin G.; Jacques, Steven L.; McCarty, Owen J. T.


    Phase contrast microscopy has become ubiquitous in the field of biology, particularly in qualitative investigations of cellular morphology. However, the use of quantitative phase retrieval methods and their connection to cellular refractive index and dry mass density remain under utilized. This is due in part to the restriction of phase and cellular mass determination to custom built instruments, involved mathematical analysis, and prohibitive sample perturbations. We introduce tomographic bright field imaging, an accessible optical imaging technique enabling the three dimensional measurement of cellular refractive index and dry mass density using a standard transillumination optical microscope. The validity of the technique is demonstrated on polystyrene spheres. The technique is then applied to the measurement of the refractive index, dry mass, volume, and density of red blood cells. This optical technique enables a simple and robust means to perform quantitative investigations of engineered and biological specimens in three dimensions using standard optical microscopes.

  9. Enzymatically Modified Low-Density Lipoprotein Promotes Foam Cell Formation in Smooth Muscle Cells via Macropinocytosis and Enhances Receptor-Mediated Uptake of Oxidized Low-Density Lipoprotein.

    Chellan, Bijoy; Reardon, Catherine A; Getz, Godfrey S; Hofmann Bowman, Marion A


    Enzyme-modified nonoxidized low-density lipoprotein (ELDL) is present in human atherosclerotic lesions. Our objective is to understand the mechanisms of ELDL uptake and its effects on vascular smooth muscle cells (SMC). Transformation of murine aortic SMCs into foam cells in response to ELDL was analyzed. ELDL, but not acetylated or oxidized LDL, was potent in inducing SMC foam cell formation. Inhibitors of macropinocytosis (LY294002, wortmannin, amiloride) attenuated ELDL uptake. In contrast, inhibitors of receptor-mediated endocytosis (dynasore, sucrose) and inhibitor of caveolae-/lipid raft-mediated endocytosis (filipin) had no effect on ELDL uptake in SMC, suggesting that macropinocytosis is the main mechanism of ELDL uptake by SMC. Receptor for advanced glycation end products (RAGE) is not obligatory for ELDL-induced SMC foam cell formation, but primes SMC for the uptake of oxidized LDL in a RAGE-dependent manner. ELDL increased intracellular reactive oxygen species, cytosolic calcium, and expression of lectin-like oxidized LDL receptor-1 in wild-type SMC but not in RAGE(-/-) SMC. The macropinocytotic uptake of ELDL is regulated predominantly by intracellular calcium because ELDL uptake was completely inhibited by pretreatment with the calcium channel inhibitor lacidipine in wild-type and RAGE(-/-) SMC. This is in contrast to pretreatment with PI3 kinase inhibitors which completely prevented ELDL uptake in RAGE(-/-) SMC, but only partially in wild-type SMC. ELDL is highly potent in inducing foam cells in murine SMC. ELDL endocytosis is mediated by calcium-dependent macropinocytosis. Priming SMC with ELDL enhances the uptake of oxidized LDL. © 2016 American Heart Association, Inc.

  10. Effects of two copper compounds on Microcystis aeruginosa cell density, membrane integrity, and microcystin release.

    Tsai, Kuo-Pei


    Microcystin release following Microcystis aeruginosa cell lysis after copper-based algaecide treatment is often cited as a concern leading to restricted use of algaecide in restoration of natural water resources. To examine this concern, bench-scale experiments were conducted to study responses of M. aeruginosa to 8-day copper exposures as copper sulfate and copper-ethanolamine (Cu-EA). M. aeruginosa UTEX 2385 was cultured in BG11 medium to cell density of 10(6)cells/mL with total and extracellular microcystin of 93 and 53μg/L, respectively. Exposures of copper concentration ranged from 40 to 1000μgCu/L. Cell membrane integrity was indicated by erythrosine B. In the end of experiment, total microcystin and cell density in untreated control (313μg/L and 10(7)cells/mL) was 3.3 and 10 times greater than pretreatment value, respectively. Minimum amount of copper required to reduce M. aeruginosa population within 8 days was 160μgCu/L as copper sulfate and 80μgCu/L as Cu-EA, where total and extracellular microcystin concentrations (47 and 44μg/L for copper sulfate; 56 and 44μg/L for Cu-EA) were degraded with degradation rate coefficient 0.1 day(-1) and were less than pretreatment values. Given a copper concentration at 80µgCu/L as Cu-EA, M. aeruginosa cells were intact and less microcystin were released compared to treatments at 160-1000µgCu/L, where lysed cells and relatively greater microcystin release were observed. Based on the laboratory results, a minimum amount of copper required for reducing M. aeruginosa population could decrease total microcystin concentration and not compromise cells and minimize microcystin release.

  11. Number Density of Mast Cells in the Primo Nodes of Rats.

    Gil, HyunJi; Bae, Kyoung-Hee; Kim, LiJung; Kim, SungChul; Soh, Kwang-Sup


    Mast cells (MCs) play a major role in allergic reactions. Surprisingly, the acupuncture points have a higher density of MCs compared with nonacupoints in the skin, which is consistent with the augmentation of the immune function by acupuncture treatment. We hypothesized that the primo vascular system (PVS), which was proposed as the anatomical structure of the acupuncture points and meridians, should have a high density of MCs. In order to test that hypothesis, we investigated the primo nodes isolated from the surfaces of internal organs, such as the liver, the small and the large intestines, and the bladder. The harvested primo nodes were stained with toluidine blue, and the MCs were easily recognized by their red-purple stains and their characteristic granules. The results showed a high density of MCs in the primo nodes and confirmed the hypothesis. The MCs were uniformly distributed in the nodes. The relative concentration of the MCs with respect to other cells was ∼15%. We divided the sizes of the primo nodes into three classes: large, medium, and small. The number density and the relative concentration of MCs did not show a size-dependence. The current work suggests that the PVS may participate in the immune response to allergic inflammation, which closely involves MCs.

  12. Regeneration and control of human fibroblast cell density by intermittently delivered pulsed electric fields.

    Golberg, Alexander; Bei, Marianna; Sheridan, Robert L; Yarmush, Martin L


    Proliferative scarring is a human disease with neither available effective treatment nor relevant animal model. One of the hypotheses for scar formation involves deregulation of fibroblast signaling and delayed apoptosis. Here, we introduce a new chemical-free method for fibroblast density control in culture by intermittently delivered pulsed electric fields (IDPEF), which cause irreversible damage to cell membranes. Using 5-100 pulses with electric field strength of 150 V/mm, pulse duration 70 µs, and frequency of 1 Hz, we investigated the effects of PEF application on growth, death, and regeneration of normal human dermal fibroblasts in culture. We found that the fraction of fibroblasts that survive depends on the number of pulses applied and follows a Weibull distribution. We have successfully developed an IDPEF protocol that controls fibroblasts density in culture. Specifically, through application of IDPEF every 72 h for 12 days, we maintain a normal human dermal fibroblast density in the 3.1 ± 0.2 × 10(5) -1.4 ± 0.2 × 10(5)  cell/mL range. Our results suggest that IDPEFs may prove useful as a non-chemical method for fibroblast density control in human wound healing.

  13. Results of Current Density Distribution Mapping in PEM Fuel Cells Dependent on Operation Parameters

    Zbigniew A. Styczynski


    Full Text Available This paper presents in situ measurements of a newly developed current density measurement system for proton exchange membrane fuel cells (PEMFC. While the functional principle and technical evaluation of the measurement system were presented in a previous paper, this paper analyzes the influence of various operation parameters, including multiple start-stop operation, at the anode, cathode and cooling locations on the distribution and long-term development of the current density. The system was operated for 500 h over two years with long periods of inactivity between measurements. The measurement results are evaluated and provide additional information on how to optimize the operation modes of fuel cells, including the start and stop of such systems as well as the water balance.

  14. Direct determination of defect density of states in organic bulk heterojunction solar cells

    Verma, Upkar K.; Tripathi, Durgesh C.; Mohapatra, Y. N.


    The measurement of the occupied trap density of states (DOS) is important for optimization of organic bulk heterojunction solar cells. We demonstrate a direct method for obtaining it from the trap related peak in capacitance-voltage characteristics under different levels of illumination, and its correlation with the dark current density-voltage characteristics. We use the method to measure the parameters of DOS, occupied trap distribution, and its temperature dependence for poly(3-hexathiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) based solar cells. The total occupied trap concentration is approximately 7 × 1015 cm-3 with a standard deviation for a truncated Gaussian distribution varying between 32 and 44 meV in the temperature range of 310-270 K within a total Gaussian DOS with a standard deviation of 92 meV.

  15. High Population Density of Juvenile Chum Salmon Decreased the Number and Sizes of Growth Hormone Cells in the Pituitary

    Salam, Md. Abdus; Ota, Yuki; Ando, Hironori; Fukuwaka, Masa-aki; Kaeriyama, Masahide; Urano, Akihisa


    Juveniles of chum salmon (Oncorhynchus keta) held at high population density were apparently smaller than those held at medium and low population densities. The effects of high population density on pituitary growth hormone (GH) cells in juvenile chum salmon were examined using immunocytochemical and in situ hybridization techniques. The ratio of GH-immunoreactive (ir) area to the whole pituitary was almost constant in all of the high, medium and low population density groups, although the nu...

  16. Correlation of Lymph Node Density With Negative Outcome Predictors in Oral and Maxillofacial Squamous Cell Carcinoma.

    Kim, Roderick Youngdo; Ward, Brent Benson; Brockhoff, Hans C; Helman, Joseph I; Braun, Thomas M; Skouteris, Christos A


    Lymph node density is defined as the number of positive lymph nodes per total number of excised lymph nodes. In oral and maxillofacial cancer, there are recent data showing that increased lymph node density leads to worse outcomes for patients. However, data correlating lymph node density with other known risk parameters are lacking. This study investigated whether a direct correlation exists among cervical lymph node density, depth of invasion, perineural invasion, and extracapsular tumor spread. A retrospective chart review was undertaken to include all patients who underwent neck dissection with resection of primary oral and maxillofacial squamous cell carcinoma from January 2009 through July 2014. After applying the exclusion criteria, 286 patients were identified. Primary tumor depth of invasion, perineural invasion, and lymph node status, including extracapsular spread, were obtained from the standard pathology report. Descriptive statistics were applied. The association between 2 continuous tumor characteristics was summarized with the Pearson correlation coefficient, and the association between a continuous and a binary tumor characteristic was summarized with 2-sample t test. Statistical significance for the study was set at a P value less than .05. Mean age at time of surgery was 63.9 ± 12.5 years. The final study included 169 men and 117 women (N = 286). The mean depth of invasion was 12.3 ± 11 mm (range, 1 to 69 mm). Mean lymph node density was 0.04 ± 0.1 (range, 0 to 0.81). There was a positive association between lymph node density and depth of tumor invasion (Pearson correlation coefficient, r = 0.21; P negative; P negative; P correlated with other known prognostic features that lead to poor outcomes. Lymph node density could be an important feature to capture in future prospective trials. Pathology standards would be crucial in this endeavor. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc

  17. Effect of coating density on oxidation resistance and Cr vaporization from solid oxide fuel cell interconnects

    Talic, Belma; Falk-Windisch, Hannes; Venkatachalam, Vinothini; Hendriksen, Peter Vang; Wiik, Kjell; Lein, Hilde Lea


    Manganese cobalt spinel oxides are promising materials for protective coatings for solid oxide fuel cell (SOFC) interconnects. To achieve high density such coatings are often sintered in a two-step procedure, involving heat treatment first in reducing and then in oxidizing atmospheres. Sintering the coating inside the SOFC stack during heating would reduce production costs, but may result in a lower coating density. The importance of coating density is here assessed by characterization of the oxidation kinetics and Cr evaporation of Crofer 22 APU with MnCo1.7Fe0.3O4 spinel coatings of different density. The coating density is shown to have minor influence on the long-term oxidation behavior in air at 800 °C, evaluated over 5000 h. Sintering the spinel coating in air at 900 °C, equivalent to an in-situ heat treatment, leads to an 88% reduction of the Cr evaporation rate of Crofer 22 APU in air-3% H2O at 800 °C. The air sintered spinel coating is initially highly porous, however, densifies with time in interaction with the alloy. A two-step reduction and re-oxidation heat treatment results in a denser coating, which reduces Cr evaporation by 97%.

  18. Systems biology. Conditional density-based analysis of T cell signaling in single-cell data.

    Krishnaswamy, Smita; Spitzer, Matthew H; Mingueneau, Michael; Bendall, Sean C; Litvin, Oren; Stone, Erica; Pe'er, Dana; Nolan, Garry P


    Cellular circuits sense the environment, process signals, and compute decisions using networks of interacting proteins. To model such a system, the abundance of each activated protein species can be described as a stochastic function of the abundance of other proteins. High-dimensional single-cell technologies, such as mass cytometry, offer an opportunity to characterize signaling circuit-wide. However, the challenge of developing and applying computational approaches to interpret such complex data remains. Here, we developed computational methods, based on established statistical concepts, to characterize signaling network relationships by quantifying the strengths of network edges and deriving signaling response functions. In comparing signaling between naïve and antigen-exposed CD4(+) T lymphocytes, we find that although these two cell subtypes had similarly wired networks, naïve cells transmitted more information along a key signaling cascade than did antigen-exposed cells. We validated our characterization on mice lacking the extracellular-regulated mitogen-activated protein kinase (MAPK) ERK2, which showed stronger influence of pERK on pS6 (phosphorylated-ribosomal protein S6), in naïve cells as compared with antigen-exposed cells, as predicted. We demonstrate that by using cell-to-cell variation inherent in single-cell data, we can derive response functions underlying molecular circuits and drive the understanding of how cells process signals. Copyright © 2014, American Association for the Advancement of Science.

  19. Retinal ganglion cell density of the black rhinoceros (Diceros bicornis): calculating visual resolution.

    Pettigrew, John D; Manger, Paul R


    A single right retina from a black rhinoceros was whole mounted, stained and analyzed to determine the visual resolution of the rhinoceros, an animal with reputedly poor eyesight. A range of small (15-microm diameter) to large (100-microm diameter) ganglion cell types was seen across the retina. We observed two regions of high density of retinal ganglion cells at either end of a long, but thin, horizontal streak. The temporal specialization, which receives light from the anterior visual field, exhibited a ganglion cell density of approximately 2000/mm2, while the nasal specialization exhibited a density of approximately 1500/mm2. The retina exhibited a ganglion cell density bias toward the upper half, especially so, the upper temporal quadrant, indicating that the rhinoceros would be processing visual information from the visual field below the anterior horizon for the most part. Our calculations indicate that the rhinoceros has a visual resolution of 6 cycles/degree. While this resolution is one-tenth that of humans (60 cycles/deg) and less than that of the domestic cat (9 cycles/deg), it is comparable to that of the rabbit (6 cycles/deg), and exceeds that seen in a variety of other mammals including seals, dolphins, microbats, and rats. Thus, the reputation of the rhinoceros as a myopic, weakly visual animal is not supported by our observations of the retina. We calculate that the black rhinoceros could readily distinguish a 30 cm wide human at a distance of around 200 m given the appropriate visual background.

  20. Advanced Microbial Fuel Cell Development, Miniaturization and Energy and Power Density Enhancement


    fuel cell development, miniaturization, and energy and power density enhancement. The anode is very important in the performance of a microbial fuel cell "MFC", and is often the limiting factor for a high power output. In present work, we used the CNT/PANI composite as the anode materials of MFCs for the first time and investigated the electrocatalytic properties of the composite associated with the bacterium biocatalyst. A method was developed to fabricate a nanostructured CNT/PANI composite anode for

  1. Evaluation of Mast Cell and Blood Vessel Density in Inflammatory Periapical Lesions

    Safoura Seifi


    Full Text Available Introduction: Radicular cystsand periapical granulomas are the most common periapical inflammatory lesions. However, the role of cellular immunity and microvessels in their pathogenesis remains unknown. The aim of this study was to evaluate the mast cell density (MCD, mircovessel density (MVD and investigating the correlation between their densities with each other in the above mentioned lesions.Materials & Methods: In this descriptive cross-sectional study, 40 paraffin blocks of mentioned lesions were selected from achieves of School of Dentistry, Babol University of Medical Sciences. Three sections were prepared from each block and stained by hematoxylin-eosin, toluidine blue, and immunohistochemically for CD34 to determine the score of inflammation, presence of mast cells and degranulatedmast cells (DMCs, and MVD, respectively. The correlation between MCD and either inflammatory infiltrate or MVD was evaluated. Data analyzed by t student, Mann-Whitney and Spearman test.Results: Mast cells were present in all periapical inflammatory lesions; 15.4±14.8 for MCD, 7.2±6.1 for DMCs, and the ratio of DMCs to total number of MCs was 0.354±0.166 and 14.8+4.44 for blood vessel density in radicular cyst and 8.52±6.75, 2.91±2.1, 0.196±0.194 and 13±8.02 in periapical granulomas, respectively. There was a positive correlation between MCD and MVD in radicular cyst (P=0.03, r=0.341, but not in periapical granulomas (P=0.6, r=0.124. MCD and MVD increased with the score of inflammation in radicular cyst (P=0.001, r=0.7 and periapical granuloma (P=0.012, r=0.54.Conclusion: Mast cells and microvessels play a role in pathogenesis of periapical inflammatory lesions. In this study, the density of mast cells and DMCs in radicular cyst was higher than periapical granulomas, but no difference was observed regarding MVD in periapical inflammatory lesions. It seems that the relationship between MCD and MVD is different based on the clinical stage of periapical

  2. Cheese whey-induced high-cell-density production of recombinant proteins in Escherichia coli

    Neubauer Peter


    Full Text Available Abstract Background Use of lactose-rich concentrates from dairy processes for the induction of recombinant gene's expression has not received much attention although they are interesting low cost substrates for production of recombinant enzymes. Applicability of dairy waste for induction of recombinant genes in Escherichia coli was studied. Clones expressing Lactobacillus phage muramidase and Lactobacillus alcohol dehydrogenase were used for the experiments. Results Shake flask cultivations in mineral salt medium showed that cheese whey or deproteinised whey induced gene expression as efficiently as IPTG (isopropyl-β-D-thiogalactopyranoside or pure lactose. Addition of yeast extract or proteolytically degraded whey proteins did not improve the recombinant protein yield. In contrast, addition of yeast extract to the well-balanced mineral salt medium decreased the product yield. Feeding with glycerol provided sufficient amount of easily assimilable carbon source during the induction period without preventing lactose intake and induction by lactose. High-cell-density fed-batch cultivations showed that product yields comparable to IPTG-induction can be achieved by feeding bacteria with a mixture of glycerol and concentrated whey permeate during the induction. Conclusion Whey and concentrated whey permeate can be applied as an alternative inducer in recombinant high-cell-density fed-batch fermentations. The yield of the recombinant product was comparable to fermentations induced by IPTG. In low-cell-density shake flask experiments the yield was higher with whey or whey permeate than with IPTG.

  3. Relationship of mast cell density with lymphangiogenesis and prognostic parameters in breast carcinoma

    Sevinc H. Keser


    Full Text Available In many cancers, mast cell density (MCD in the tumor microenvironment is associated with tumor progression and, to a greater extent, angiogenesis. Our study was designed to investigate the correlation between MCD, tumor lymphangiogenesis, and several well-established prognostic parameters in breast cancer. One hundred and four cases of invasive breast carcinoma diagnosed in our clinic between 2007 and 2011 were included. Mast cells and lymphatic vessels were stained with toluidine blue and D2-40, respectively, and their densities were calculated in various areas of tumors and lymph nodes. The variables of MCD and lymphatic vessel density (LVD were compared using prognostic parameters as well as with each other. As tumor size and volume increased, MCD increased comparably in metastatic lymph nodes; intratumoral and peritumoral LVD also increased. Lymphovascular invasion, lymphatic invasion, perineural invasion, and estrogen receptor positivity were positively related to intratumoral MCD. The relationship between peritumoral MCD and nontumoral breast tissue MCD was statistically significant. Stage was correlated with MCD in metastatic lymph nodes. Metastatic lymph node MCD and intratumoral MCD were also significantly related. Stage, lymphatic invasion, perineural invasion, lymphovascular invasion, and metastatic lymph node MCD were all correlated with intratumoral and/or peritumoral LVD. As nuclear grade increased, intratumoral LVD became higher. In breast carcinoma, MCD, depending on its location, was related to several prognostic parameters. Notably, mast cells may have at least some effect on lymphangiogenesis, which appears to be a predictor of tumor progression.

  4. Cheese whey-induced high-cell-density production of recombinant proteins in Escherichia coli.

    Viitanen, Mikko I; Vasala, Antti; Neubauer, Peter; Alatossava, Tapani


    BACKGROUND: Use of lactose-rich concentrates from dairy processes for the induction of recombinant gene's expression has not received much attention although they are interesting low cost substrates for production of recombinant enzymes. Applicability of dairy waste for induction of recombinant genes in Escherichia coli was studied. Clones expressing Lactobacillus phage muramidase and Lactobacillus alcohol dehydrogenase were used for the experiments. RESULTS: Shake flask cultivations in mineral salt medium showed that cheese whey or deproteinised whey induced gene expression as efficiently as IPTG (isopropyl-beta-D-thiogalactopyranoside) or pure lactose. Addition of yeast extract or proteolytically degraded whey proteins did not improve the recombinant protein yield. In contrast, addition of yeast extract to the well-balanced mineral salt medium decreased the product yield. Feeding with glycerol provided sufficient amount of easily assimilable carbon source during the induction period without preventing lactose intake and induction by lactose. High-cell-density fed-batch cultivations showed that product yields comparable to IPTG-induction can be achieved by feeding bacteria with a mixture of glycerol and concentrated whey permeate during the induction. CONCLUSION: Whey and concentrated whey permeate can be applied as an alternative inducer in recombinant high-cell-density fed-batch fermentations. The yield of the recombinant product was comparable to fermentations induced by IPTG. In low-cell-density shake flask experiments the yield was higher with whey or whey permeate than with IPTG.

  5. Maximum Autocorrelation Factorial Kriging

    Nielsen, Allan Aasbjerg; Conradsen, Knut; Pedersen, John L.


    This paper describes maximum autocorrelation factor (MAF) analysis, maximum autocorrelation factorial kriging, and its application to irregularly sampled stream sediment geochemical data from South Greenland. Kriged MAF images are compared with kriged images of varimax rotated factors from...

  6. Retroendocytosis of high density lipoproteins by the human hepatoma cell line, HepG2

    Kambouris, A.M.; Roach, P.D.; Calvert, G.D.; Nestel, P.J. (CSIRO, Division of Human Nutrition, Adelaide (Australia))


    When human HepG2 hepatoma cells were pulsed with 125I-labeled high density lipoproteins (HDL) and chased in fresh medium, up to 65% of the radioactivity released was precipitable with trichloroacetic acid. Cell-internalized 125I-HDL contributed to the release of acid-precipitable material; when cells were treated with trypsin before the chase to remove 125I-HDL bound to the outer cell membrane, 50% of the released material was still acid-precipitable. Characterization of the radioactive material resecreted by trypsinized cells revealed the presence of particles that were similar in size and density to mature HDL and contained intact apolipoproteins (apo) A-I and A-II. The release of internalized label occurred at 37 degrees C but not at 4 degrees C. Monensin, which inhibits endosomal recycling of receptors, decreased the binding of 125I-HDL to cells by 75%, inhibited the release of internalized radioactivity as acid-precipitable material by 80%, and increased the release of acid-soluble material by 90%. In contrast, the lysosomal inhibitor chloroquine increased the association of 125I-HDL to cells by 25%, inhibited the release of precipitable material by 10%, and inhibited the release of acid-soluble radioactivity by 80%. Pre-incubation with cholesterol caused a 50% increase in the specific binding, internalization, and resecretion of HDL label. Cholesterol affected the release of acid-precipitable label much more (+90%) than that of acid-soluble material (+20%). Taken together, these findings suggest that HepG2 cells can bind, internalize, and resecrete HDL by a retroendocytotic process. Furthermore, the results with cholesterol and monensin indicate that a regulated, recycling, receptor-like molecule is involved in the binding and intracellular routing of HDL.

  7. Mean and maximum standardized uptake values in [{sup 18}F]FDG-PET for assessment of histopathological response in oesophageal squamous cell carcinoma or adenocarcinoma after radiochemotherapy

    Schmidt, Matthias; Dietlein, Markus; Kobe, Carsten; Eschner, Wolfgang; Schicha, Harald [University of Cologne, Department of Nuclear Medicine, Cologne (Germany); Bollschweiler, Elfriede; Moenig, Stefan P.; Vallboehmer, Daniel; Hoelscher, Arnulf [University of Cologne, Department of General-, Visceral and Cancer Surgery, Cologne (Germany)


    To evaluate the potential of [{sup 18}F]fluorodeoxyglucose positron emission tomography (FDG-PET) for the assessment of histopathological response and survival after neoadjuvant radiochemotherapy in patients with oesophageal cancer. In 2005 and 2006, 55 patients (43 men, 12 women; median age 60 years) with locally advanced oesophageal cancer (cT3-4 Nx M0; 24 with squamous cell carcinoma, 31 with adenocarcinoma) underwent transthoracic en bloc oesophagectomy after completion of treatment with cisplatin, 5-fluorouracil, and radiotherapy ad 36 Gy in a prospective clinical trial. Of the 55 patients, 21 (38%) were classified as histopathological responders (<10% vital residual tumour cells) and 34 (62%) as nonresponders. FDG-PET was performed before (PET 1) and 3-4 weeks after the end (PET 2) of radiochemotherapy with assessment of maximum and average standardized uptake values (SUV) for correlation with histopathological response and survival. Histopathological responders had a slightly higher baseline SUV than nonresponders (p<0.0001 between PET 1 and PET 2 for responders and nonresponders) and the decrease was more prominent in responders. Except for SUVmax in patients with squamous cell carcinoma neither baseline nor preoperative SUV nor percent SUV reduction correlated significantly with histopathological response. Histopathological responders had a 2-year overall survival of 91 {+-} 9% and nonresponders a survival of 53 {+-} 10% (p = 0.007). Our study does not support recent reports that FDG-PET predicts histopathological response and survival in patients with locally advanced oesophageal cancer treated by neoadjuvant radiochemotherapy. (orig.)

  8. Hepatitis C virus coinfection does not influence the CD4 cell recovery in HIV-1-infected patients with maximum virologic suppression

    Peters, Lars; Mocroft, Amanda; Soriano, Vincent;


    BACKGROUND: Conflicting data exist whether hepatitis C virus (HCV) affects the CD4 cell recovery in patients with HIV starting antiretroviral treatment. OBJECTIVE: To investigate the influence of HCV coinfection on the CD4 recovery in patients with maximum virologic suppression within the Euro......SIDA cohort. METHODS: Patients tested for anti-HCV antibodies and with at least 2 consecutive HIV viral loads (VLs) ... was calculated and compared between (1) HCV-seronegative vs. HCV-seropositive patients, (2) HCV genotypes 1-4 in HCV-RNA+ patients, and (3) viremic vs. aviremic (HCV-RNA HCV-seropositive patients. Results were adjusted for known confounders. RESULTS: Four thousand two hundred eight patients were...

  9. Oxygen supply in disposable shake-flasks: prediction of oxygen transfer rate, oxygen saturation and maximum cell concentration during aerobic growth.

    Schiefelbein, Sarah; Fröhlich, Alexander; John, Gernot T; Beutler, Falco; Wittmann, Christoph; Becker, Judith


    Dissolved oxygen plays an essential role in aerobic cultivation especially due to its low solubility. Under unfavorable conditions of mixing and vessel geometry it can become limiting. This, however, is difficult to predict and thus the right choice for an optimal experimental set-up is challenging. To overcome this, we developed a method which allows a robust prediction of the dissolved oxygen concentration during aerobic growth. This integrates newly established mathematical correlations for the determination of the volumetric gas-liquid mass transfer coefficient (kLa) in disposable shake-flasks from the filling volume, the vessel size and the agitation speed. Tested for the industrial production organism Corynebacterium glutamicum, this enabled a reliable design of culture conditions and allowed to predict the maximum possible cell concentration without oxygen limitation.

  10. Cell density-dependent stimulation of PAI-1 and hyaluronan synthesis by TGF-β in orbital fibroblasts.

    Galgoczi, Erika; Jeney, Florence; Gazdag, Annamaria; Erdei, Annamaria; Katko, Monika; Nagy, Domonkos M; Ujhelyi, Bernadett; Steiber, Zita; Gyory, Ferenc; Berta, Eszter; Nagy, Endre V


    During the course of Graves' orbitopathy (GO), orbital fibroblasts are exposed to factors that lead to proliferation and extracellular matrix (ECM) overproduction. Increased levels of tissue plasminogen activator inhibitor type 1 (PAI-1 (SERPINE1)) might promote the accumulation of ECM components. PAI-1 expression is regulated by cell density and various cytokines and growth factors including transforming growth factorβ(TGF-β). We examined the effects of increasing cell densities and TGF-β on orbital fibroblasts obtained from GO patients and controls. Responses were evaluated by the measurement of proliferation, PAI-1 expression, and ECM production. There was an inverse correlation between cell density and the per cell production of PAI-1. GO orbital, normal orbital, and dermal fibroblasts behaved similarly in this respect. Proliferation rate also declined with increasing cell densities. Hyaluronan (HA) production was constant throughout the cell densities tested in all cell lines. In both GO and normal orbital fibroblasts, but not in dermal fibroblasts, TGF-β stimulated PAI-1 production in a cell density-dependent manner, reaching up to a five-fold increase above baseline. This has been accompanied by increased HA secretion and pericellular HA levels at high cell densities. Increasing cell density is a negative regulator of proliferation and PAI-1 secretion both in normal and GO orbital fibroblasts; these negative regulatory effects are partially reversed in the presence of TGF-β. Cell density-dependent regulation of PAI-1 expression in the orbit, together with the local cytokine environment, may have a regulatory role in the turnover of the orbital ECM and may contribute to the expansion of orbital soft tissue in GO.

  11. Role of cellular density, in vitro, in anti-tumor activity of CFA-treated and immunized cells.

    Uyeki, E M; Truitt, G A; Bisel, T U


    Incorporation of tritiated deoxythymidine (3HdT) into DNA was used to measure growth, in vitro, of P815 tumor cells admixed with spleen and peritoneal effector cells. At a high tumor cell density ((1x10(5) cells per dish), using anti-theta and anti-macrophage sera, T-cells and macrophages from the peritoneum of immunized mice could be identified as cells possessing anti-tumor activity. A nonspecific inhibition by normal effector cells, which occurred at the high tumor cell density, did not occur at a lower tumor cell density (1x10(4) cells per dish). Therefore, the effects of immunization and Freund's adjuvant treatment on the anti-tumor activity of effector cells were determined more accurately when normal cells were no longer inhibitory. Thus, experimental variables dealing with cellular density (cells/mm2 of the culture vessel surface) and effector:tumor cell ratios play an important role in the anti-proliferative capacity of effector cells.

  12. Increasing Vero viable cell densities for yellow fever virus production in stirred-tank bioreactors using serum-free medium.

    Mattos, Diogo A; Silva, Marlon V; Gaspar, Luciane P; Castilho, Leda R


    In this work, changes in Vero cell cultivation methods have been employed in order to improve cell growth conditions to obtain higher viable cell densities and to increase viral titers. The propagation of the 17DD yellow fever virus (YFV) in Vero cells grown on Cytodex I microcarriers was evaluated in 3-L bioreactor vessels. Prior to the current changes, Vero cells were repeatedly displaying insufficient microcarrier colonization. A modified cultivation process with four changes has resulted in higher cell densities and higher virus titers than previously observed for 17DD YFV.

  13. Reactor-scale cultivation of the hyperthermophilic methanarchaeon Methanococcus jannaschii to high cell densities.

    Mukhopadhyay, B; Johnson, E F; Wolfe, R S


    For the hyperthermophilic and barophilic methanarchaeon Methanococcus jannaschii, we have developed a medium and protocols for reactor-scale cultivation that improved the final cell yield per liter from approximately 0.5 to approximately 7.5 g of packed wet cells ( approximately 1.8 g dry cell mass) under autotrophic growth conditions and to approximately 8.5 g of packed wet cells ( approximately 2 g dry cell mass) with yeast extract (2 g liter(-1)) and tryptone (2 g liter(-1)) as medium supplements. For growth in a sealed bottle it was necessary to add Se to the medium, and a level of 2 microM for added Se gave the highest final cell yield. In a reactor M. jannaschii grew without added Se in the medium; it is plausible that the cells received Se as a contaminant from the reactor vessel and the H(2)S supply. But, for the optimal performance of a reactor culture, an addition of Se to a final concentration of 50 to 100 microM was needed. Also, cell growth in a reactor culture was inhibited at much higher Se concentrations. These observations and the data from previous work with methanogen cell extracts (B. C. McBride and R. S. Wolfe, Biochemistry 10:4312-4317, 1971) suggested that from a continuously sparged reactor culture Se was lost in the exhaust gas as volatile selenides, and this loss raised the apparent required level of and tolerance for Se. In spite of having a proteinaceous cell wall, M. jannaschii withstood an impeller tip speed of 235.5 cms(-1), which was optimal for achieving high cell density and also was the higher limit for the tolerated shear rate. The organism secreted one or more acidic compounds, which lowered pH in cultures without pH control; this secretion continued even after cessation of growth.

  14. Mast cell density and the context of clinicopathological parameters and expression of p185,estrogen receptor,and proliferating cell nuclear antigen in gastric carcinoma

    Ying-AnJiang; You-YuanZhang; He-ShengLuo; Shou-FuXing


    AIM:To investigate the relationship between the mast cell density(MCD)and the context of clinicopathological parameters and expression of p185,estrogen receptor(ER),and proliferating cell nuclear antigen(PCNA)in gastric carcinoma.

  15. Current density distribution mapping in PEM fuel cells as an instrument for operational measurements

    Geske, M.; Heuer, M.; Heideck, G.; Styczynski, Z. A. [Otto-von-Guericke University Magdeburg, Chair Electric Power Networks and Renewable Energy Sources, Magdeburg (Germany)


    A newly developed measurement system for current density distribution mapping has enabled a new approach for operational measurements in proton exchange membrane fuel cells (PEMFC). Taking into account previously constructed measurement systems, a method based on a multi layer printed circuit board was chosen for the development of the new system. This type of system consists of a sensor, a special electronic device and the control and visualization PC. For the acquisition of the current density distribution values, a sensor device was designed and installed within a multilayer printed circuit board with integrated shunt resistors. Varying shunt values can be taken into consideration with a newly developed and evaluated calibration method. The sensor device was integrated in a PEM fuel cell stack to prove the functionality of the whole measurement system. A software application was implemented to visualize and save the measurement values. Its functionality was verified by operational measurements within a PEMFC system. Measurement accuracy and possible negative reactions of the sensor device during PEMFC operation are discussed in detail in this paper. The developed system enables operational measurements for different operating phases of PEM fuel cells. Additionally, this can be seen as a basis for new opportunities of optimization for fuel cell design and operation modes. (author)

  16. Evaluating effect of surface state density at the interfaces in degraded bulk heterojunction organic solar cell

    Arora, Swati, E-mail: [Department of Physics, Zakir Husain College, University of Delhi, Delhi 110002 (India); Singh, Vinamrita [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Arora, Manoj [Department of Physics, Ramjas College, University of Delhi, Delhi 110007 (India); Pal Tandon, Ram [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)


    Degradation and short shelf life have been observed experimentally in poly(3-hexylthiophene) (P3HT): 6,6-phenyl C61-butyric acid methyl ester (PCBM) based blend solar cells. Both dark and illuminated current-voltage characteristics could be explained quantitatively with a proposed single model for a typical degraded organic solar cell-glass/ITO/PEDOT:PSS/P3HT:PCBM/Al. It has been found that surface state density, interface thickness, tunneling coefficient and occupation probabilities of the interface states becomes important with the passage of time. To look into the problem the activity at ITO/PEDOT:PSS and P3HT:PCBM/Al interfaces are studied using realistic values of the interfaces. The experimental J-V characteristics is well explained with the inclusion of tunneling current through these surface states and becomes the dominant current component for the degraded cell. It is also found that surface state density increases to 10{sup 12}-10{sup 13} cm{sup -2} eV{sup -1}, which has been verified with C-V measurements and also is in agreement with our proposed model for BHJ solar cell after 150 h of fabrication.

  17. Current Density Distribution Mapping in PEM Fuel Cells as An Instrument for Operational Measurements

    Martin Geske


    Full Text Available A newly developed measurement system for current density distribution mapping has enabled a new approach for operational measurements in proton exchange membrane fuel cells (PEMFC. Taking into account previously constructed measurement systems, a method based on a multi layer printed circuit board was chosen for the development of the new system. This type of system consists of a sensor, a special electronic device and the control and visualization PC. For the acquisition of the current density distribution values, a sensor device was designed and installed within a multilayer printed circuit board with integrated shunt resistors. Varying shunt values can be taken into consideration with a newly developed and evaluated calibration method. The sensor device was integrated in a PEM fuel cell stack to prove the functionality of the whole measurement system. A software application was implemented to visualize and save the measurement values. Its functionality was verified by operational measurements within a PEMFC system. Measurement accuracy and possible negative reactions of the sensor device during PEMFC operation are discussed in detail in this paper. The developed system enables operational measurements for different operating phases of PEM fuel cells. Additionally, this can be seen as a basis for new opportunities of optimization for fuel cell design and operation modes.

  18. High-density cell systems incorporating polymer microspheres as microenvironmental regulators in engineered cartilage tissues.

    Solorio, Loran D; Vieregge, Eran L; Dhami, Chirag D; Alsberg, Eben


    To address the significant clinical need for tissue-engineered therapies for the repair and regeneration of articular cartilage, many systems have recently been developed using bioactive polymer microspheres as regulators of the chondrogenic microenvironment within high-density cell cultures. In this review, we highlight various densely cellular systems utilizing polymer microspheres as three-dimensional (3D) structural elements within developing engineered cartilage tissue, carriers for cell expansion and delivery, vehicles for spatiotemporally controlled growth factor delivery, and directors of cell behavior via regulation of cell-biomaterial interactions. The diverse systems described herein represent a shift from the more traditional tissue engineering approach of combining cells and growth factors within a biomaterial scaffold, to the design of modular systems that rely on the assembly of cells and bioactive polymer microspheres as building blocks to guide the creation of articular cartilage. Cell-based assembly of 3D microsphere-incorporated structures represents a promising avenue for the future of tissue engineering.

  19. Hydroxysafflor yellow A suppresses oxidized low density lipoprotein induced proliferation of vascular smooth muscle cells

    Lin Sheng


    Full Text Available To investigate the relationship between the suppression of Hydroxysafflor yellow A (HSYA on the oxidized low density lipoprotein (ox-LDL induced proliferation of vascular smooth muscle cells (VSMCs and the mRNA and protein expression of extracellular signal-regulated protein kinase 1/2 (ERK1/2 and mitogen activated protein kinase phospholipase-1 (MAKP-1, VSMCs were treated with HSYA at 10 ?mol/L and/or ox-LDL at 35 mg/L for 48 h. MTT assay was done to measure cell survival rate, flow cytometry to detect cell cycle, reverse transcription PCR and Western blot to detect the expression of ERK1/2 and MAKP-1. When compared to cells treated with ox-LDL alone, the survival rate of cells treated with two reagents was reduced and the proportion of cells in G0/G1 phase significantly increased, with increased MKP-1 expression. The study suggests HSYA can inhibit VSMC proliferation via increasing MKP-1 expression, reducing p-ERK1/2 activity and suppressing cell cycle.

  20. Development of silver-zinc cells of improved cycle life and energy density

    Serenyi, Roberto; James, Stanley D.


    Substantial increases in the cost effectiveness and range of naval underwater vehicles are possible by virtue of advances made, in this program, to silver-zinc, vehicle propulsion batteries. To improve battery cycle life and energy density, electropermeable membranes (EPM's) were used as additives and/or as coatings for the negative electrodes and as coatings for conventional separator materials. Also, bismuth oxide was tested as an additive to the negative electrodes and P2291-40/20, a radiation-grafted polyethylene film, as a separator used in conjunction with silver-treated cellophane. EPM's used as negative electrode additives and also as coatings for Celgard 2500 microporous polypropylene greatly improved cells. Cells with EPM's used as coatings for the negative electrodes failed rapidly because of an error in formulation. Cells with 10 percent bismuth oxide in the negative electrodes exhibited substantially lower capacity than the standard cells and were removed from the test. Cells with radiation-grafted polyethylene separators provided fewer cycles than the standard cells, with 5 percent higher capacity and 6 percent lower utilization of active materials by cycle 60. However, the slightly better capacity of these cells, realized due to the additional space available for active materials, does not compensate for their generally unimpressive performance.

  1. A novel rat tail collagen type-I gel for the cultivation of human articular chondrocytes in low cell density.

    Muller-Rath, R; Gavénis, K; Andereya, S; Mumme, T; Schmidt-Rohlfing, B; Schneider, U


    Collagen type-I matrix systems have gained growing importance as a cartilage repair device. However, most of the established matrix systems use collagen type-I of bovine origin seeded in high cell densities. Here we present a novel collagen type-I gel system made of rat tail collagen for the cultivation of human chondrocytes in low cell densities. Rat tail collagen type-I gel (CaReS, Arthro Kinetics, Esslingen, Germany) was seeded with human passage 2 chondrocytes in different cell densities to evaluate the optimal cell number. In vitro, the proliferation factor of low density cultures was more than threefold higher compared with high density cultures. After 6 weeks of in vitro cultivation, freshly prepared chondrocytes with an initial cell density of 2x10(5) cells/mL showed a proliferation factor of 33. A cell density of 2x10(5) cells/mL was chosen for in vitro and in vivo cultivation using the common nude mouse model as an in vivo system. Chondrocytes stayed viable as a Live/Dead fluorescence assay and TUNEL staining revealed. During in vitro cultivation, passage 0 cells partly dedifferentiated morphologically. In vivo, passage 0 cells maintained the chondrocyte phenotype and demonstrated an increased synthesis of collagen type-II protein and gene expression compared to passage 2 cells. Passage 2 cells did not redifferentiate in vivo. Cultivating a cell-seeded collagen gel of bovine origin as a control (AtelocollagenTM, Koken, Tokyo, Japan) did not lead to superior results with regard to cell morphology, col-II protein production and col-II gene expression. With the CaReS collagen gel system the best quality of repair tissue was obtained by seeding freshly isolated chondrocytes.

  2. Analysis of Tubespins as a suitable scale-down model of bioreactors for high cell density CHO cell culture.

    Gomez, Natalia; Ambhaikar, Malhar; Zhang, Li; Huang, Chung-Jr; Barkhordarian, Hedieh; Lull, Jonathan; Gutierrez, Chris


    High cell density (HCD) culture increases recombinant protein productivity via higher biomass. Compared to traditional fed-batch cultures, HCD is achieved by increased nutrient availability and removal of undesired metabolic components via regular medium replenishment. HCD process development is usually performed in instrumented lab-scale bioreactors (BR) that require time and labor for setup and operation. To potentially minimize resources and cost during HCD experiments, we evaluated a 2-week 50-mL Tubespin (TS) simulated HCD process where daily medium exchanges mimic the medium replacement rate in BR. To best assess performance differences, we cultured 13 different CHO cell lines in simulated HCD as satellites from simultaneous BR, and compared growth, metabolism, productivity and product quality. Overall, viability, cell-specific productivity and metabolism in TS were comparable to BR, but TS cell growth and final titer were lower by 25 and 15% in average, respectively. Peak viable cell densities were lower in TS than BR as a potential consequence of lower pH, different medium exchange strategy and dissolved oxygen limitations. Product quality attributes highly dependent on intrinsic molecule or cell line characteristics (e.g., galactosylation, afucosylation, aggregation) were comparable in both scales. However, product quality attributes that can change extracellularly as a function of incubation time (e.g., deamidation, C-terminal lysine, fragmentation) were in general lower in TS because of shorter residence time than HCD BR. Our characterization results and two case studies show that TS-simulated HCD cultures can be effectively used as a simple scale-down model for relative comparisons among cell lines for growth or productivity (e.g., clone screening), and for investigating effects on protein galactosylation. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:490-499, 2017. © 2017 American Institute of Chemical Engineers.

  3. Maximum-likelihood method in quantum estimation

    Paris, M G A; Sacchi, M F


    The maximum-likelihood method for quantum estimation is reviewed and applied to the reconstruction of density matrix of spin and radiation as well as to the determination of several parameters of interest in quantum optics.

  4. The effect of RGD density on osteoblast and endothelial cell behavior on RGD-grafted polyethylene terephthalate surfaces.

    Chollet, Celine; Chanseau, Christel; Remy, Murielle; Guignandon, Alain; Bareille, Reine; Labrugère, Christine; Bordenave, Laurence; Durrieu, Marie-C


    Hybrid materials combining polyethylene terephthalate and different types of cells (endothelial and osteoblastic cells) have been developed thanks to the covalent grafting of different densities of RGD containing peptides onto the polymer surface. Biomimetic modifications were performed by means of a three-step reaction procedure: creation of COOH functions, coupling agent grafting and the immobilization of the RGDC peptides. High resolution mu-imager was used to evaluate RGD densities (varying between 0.6 and 2.4 pmol/mm(2)) and has exhibited the stability of the surface grafted peptides when treated in harsh conditions. The efficiency of this route for biomimetic modification of a PET surface was demonstrated by measuring the adhesion of MC3T3 and HSVEC cells and by focal adhesion observation. Results obtained prove that a minimal RGDC density of 1 pmol/mm(2) is required to improve MC3T3 and HSVEC cells responses. Indeed, cells seeded onto a RGDC-modified PET with a density higher than 1 pmol/mm(2) were able to establish focal adhesion as visualized by fluorescence microscope compared to cells immobilized onto unmodified PET and RGDC-modified PET with densities lower than 1 pmol/mm(2). Moreover, the number of focal contacts was enhanced by the increase of RGDC peptide densities grafted onto the material surface. With this study we proved that the density of peptides immobilized on the surface is a very important parameter influencing osteoblast or endothelial cell adhesion and focal contact formation.

  5. Relation of low-intensity pulsed ultrasound to the cell density of scaffold-free cartilage in a high-density static semi-open culture system.

    Uenaka, Kazuhiro; Imai, Shinji; Ando, Kosei; Matsusue, Yoshitaka


    A scaffold-free cartilage construct, analogous to those found during embryonic precartilage condensation, has received much attention as a novel modality for tissue-engineered cartilage. In the present study, we developed an uncomplicated culture system by which scaffold-free cartilage-like tissues are produced using cell-cell interactions. With this system, we attempted to prevent dedifferentiation and reverse the phenotypic modulations by adjusting the cell density. We investigated whether low-intensity pulsed ultrasound (LIPUS) enhances matrix synthesis of the scaffold-free cartilage construct. Rat articular chondrocytes multiplied in monolayers were seeded onto the synthetic porous membrane at stepwise cell densities (i.e., 1.0, 2.0, and 4.0 × 10(7) cells/cm(2)) to allow formation of a scaffold-free cartilage construct via cell-cell interaction. The cartilage constructs were then stimulated by LIPUS for 20 min/day. To investigate the effect of LIPUS stimulation on matrix synthesis, expression of mRNA for cartilage matrix molecules was quantified by a real-time reverse transcription-polymerase chain reaction. Synthesis of type II collagen, type I collagen, and proteoglycan was also assessed histologically. Only the chondrocytes cultured at high cell densities in the 2.0 × 10(7)cells/cm(2) group became concentrated and formed a plate-like construct similar to native articular cartilage by macroscopic and histological assessments. Statistical analysis on the matrix gene expression demonstrated that the levels of type II collagen and aggrecan mRNA of the 2.0 × 10(7)cells/cm(2) group were significantly higher than with the other two cell-density groups. Interestingly, the LIPUS application led to a statistically significant enhancement of aggrecan gene expression only in the 2.0 × 10(7) cells/cm(2) group. The current study presents a semi-open static culture system that facilitates production of the scaffold-free constructs from monolayer-cultured chondrocytes

  6. Minimally modified low density lipoprotein induces monocyte chemotactic protein 1 in human endothelial cells and smooth muscle cells

    Cushing, S.D.; Berliner, J.A.; Valente, A.J.; Territo, M.C.; Navab, M.; Parhami, F.; Gerrity, R.; Schwartz, C.J.; Fogelman, A.M.


    After exposure to low density lipoprotein (LDL) that had been minimally modified by oxidation (MM-LDL), human endothelial cells (EC) and smooth muscle cells (SMC) cultured separately or together produced 2- to 3-fold more monocyte chemotactic activity than did control cells or cells exposed to freshly isolated LDL. This increase in monocyte chemotactic activity was paralleled by increases in mRNA levels for a monocyte chemotactic protein 1 (MCP-1) that is constitutively produced by the human glioma U-105MG cell line. Antibody that had been prepared against cultured baboon smooth muscle cell chemotactic factor (anti-SMCF) did not inhibit monocyte migration induced by the potent bacterial chemotactic factor f-Met-Leu-Phe. However, anti-SMCF completely inhibited the monocyte chemotactic activity found in the media of U-105MG cells, EC, and SMC before and after exposure to MM-LDL. Moreover, monocyte migration into the subendothelial space of a coculture of EC and SMC that had been exposed to MM-LDL was completely inhibited by anti-SMCF. Anti-SMCF specifically immunoprecipitated 10-kDa and 12.5-kDa proteins from EC. Incorporation of (35S)methionine into the immunoprecipitated proteins paralleled the monocyte chemotactic activity found in the medium of MM-LDL stimulated EC and the levels of MCP-1 mRNA found in the EC. We conclude that SMCF is in fact MCP-1 and MCP-1 is induced by MM-LDL.

  7. Low density of membrane particles in auditory hair cells of lizards and birds suggests an absence of somatic motility.

    Köppl, Christine; Forge, Andrew; Manley, Geoffrey A


    Hair cells are the mechanoreceptive cells of the vertebrate lateral line and inner ear. In addition to their sensory function, hair cells display motility and thus themselves generate mechanical energy, which is thought to enhance sensitivity. Two principal cellular mechanism are known that can mediate hair-cell motility in vitro. One of these is based on voltage-dependent changes of an intramembrane protein and has so far been demonstrated only in outer hair cells of the mammalian cochlea. Correlated with this, the cell membranes of outer hair cells carry an extreme density of embedded particles, as revealed by freeze fracturing. The present study explored the possibility of membrane-based motility in hair cells of nonmammals, by determining their density of intramembrane particles. Replicas of freeze-fractured membrane were prepared from auditory hair cells of a lizard, the Tokay gecko, and a bird, the barn owl. These species were chosen because of independent evidence for active cochlear mechanics, in the form of spontaneous otoacoustic emissions. For quantitative comparison, mammalian inner and outer hair cells, as well as vestibular hair, cells were reevaluated. Lizard and bird hair cells displayed median densities of 2,360 and 1,880 intramembrane particles/microm2, respectively. This was not significantly different from the densities in vestibular and mammalian inner hair cells; however, it was about half the density in of mammalian outer hair cells. This suggests that nonmammalian hair cells do not possess high densities of motor protein in their membranes and are thus unlikely to be capable of somatic motility. 2004 Wiley-Liss, Inc.

  8. Modeling quorum sensing trade-offs between bacterial cell density and system extension from open boundaries

    Marenda, Mattia; Zanardo, Marina; Trovato, Antonio; Seno, Flavio; Squartini, Andrea


    Bacterial communities undergo collective behavioural switches upon producing and sensing diffusible signal molecules; a mechanism referred to as Quorum Sensing (QS). Exemplarily, biofilm organic matrices are built concertedly by bacteria in several environments. QS scope in bacterial ecology has been debated for over 20 years. Different perspectives counterpose the role of density reporter for populations to that of local environment diffusivity probe for individual cells. Here we devise a model system where tubes of different heights contain matrix-embedded producers and sensors. These tubes allow non-limiting signal diffusion from one open end, thereby showing that population spatial extension away from an open boundary can be a main critical factor in QS. Experimental data, successfully recapitulated by a comprehensive mathematical model, demonstrate how tube height can overtake the role of producer density in triggering sensor activation. The biotic degradation of the signal is found to play a major role and to be species-specific and entirely feedback-independent.

  9. Analysis of electronic models for solar cells including energy resolved defect densities

    Glitzky, Annegret


    We introduce an electronic model for solar cells including energy resolved defect densities. The resulting drift-diffusion model corresponds to a generalized van Roosbroeck system with additional source terms coupled with ODEs containing space and energy as parameters for all defect densities. The system has to be considered in heterostructures and with mixed boundary conditions from device simulation. We give a weak formulation of the problem. If the boundary data and the sources are compatible with thermodynamic equilibrium the free energy along solutions decays monotonously. In other cases it may be increasing, but we estimate its growth. We establish boundedness and uniqueness results and prove the existence of a weak solution. This is done by considering a regularized problem, showing its solvability and the boundedness of its solutions independent of the regularization level. (orig.)

  10. Distribution of the Current Density in Electrolyte of the Pem Fuel Cell

    Eugeniusz Kurgan


    Full Text Available In this paper water management in proton exchange membrane (PEM fuel cell is considered. Firt mass convervation law for water is applied. Next proton transport is described by the Nernst-Planck equation and liqid water convection velocity is eliminated by the Schlogl equation. Electro-osmotic drag coefficient is related to hydrogen index and experimentally determined swelling coefficient. Three partial differential equations for molar water concentration Cw, electric potential ϕ and water pressure Pw are formulated. Current density vector i is derived from proton flux expression. These equations together with adequate boundary conditions were solved using finite element method. The distribution of electric potential and current density in function of geometrical parametres is investigated. At the end some illustrative example is given.

  11. Cellular uptake of a dexamethasone palmitate-low density lipoprotein complex by macrophages and foam cells.

    Tauchi, Yoshihiko; Chono, Sumio; Morimoto, Kazuhiro


    To evaluate the utility of a dexamethasone palmitate (DP)-low density lipoprotein (LDL) complex to transport drug into foam cells, the cellular uptake of DP-LDL complex by macrophages and foam cells was examined. The DP-LDL complex was prepared by incubation with DP and LDL, and the DP-LDL complex and murine macrophages were incubated. No cellular uptake of the DP-LDL complex by macrophages was found until 6 h after the start of incubation, but this gradually increased from 12 to 48 h. On the other hand, the cellular uptake of the oxidized DP-LDL complex was already apparent at 3 h after the start incubation, and then markedly increased until 48 h incubation along with that of the lipid emulsion (LE) containing DP (DP-LE). The cellular uptake of DP-LE by foam cells was significantly lower than that by macrophages. However, the cellular uptake of DP-LDL complex by foam cells was similar to that by macrophages. These findings suggest that the DP-LDL complex is oxidatively modified, and then incorporated into macrophages and foam cells through the scavenger receptor pathway. Since selective delivery of drugs into foam cells in the early stage of atherosclerosis is a useful protocol for antiatherosclerosis treatment, the DP-LDL complex appears to be a potentially useful drug-carrier complex for future antiatherosclerotic therapy.

  12. Non-invasive optoacoustic probing of the density and stiffness of single biological cells

    Dehoux, T.; Audoin, B.


    Recently, the coherent generation of GHz acoustic waves using ultrashort laser pulses has demonstrated the ability to probe the sound velocity in vegetal cells and in cell-mimicking soft micro-objects with micrometer resolution, opening tremendous potentialities for single-cell biology. However, manipulating biological media in physiological conditions is often a technical challenge when using a laser-based setup. In this article, we present a new opto-acoustic bio-transducer composed of a thin metal film sputtered on a transparent heat sink that allows reducing importantly the laser-induced cellular stresses, and offers a wide variety of optical configurations. In particular, by exploiting the acoustic reflection coefficient at the sample-transducer interface and the photoacoustic interaction inside the transparent sample, the density and compressibility of the sample can be probed simultaneously. Using an ad hoc signal analysis based on Hilbert and wavelet transforms, these quantities are measured accurately for a reference fluid. Similar analysis performed in a single vegetal cell also suggests high sensitivity to the state of the transducer-cell interface, and notably to the presence of the plasma membrane that encloses the cell vacuole.

  13. Metronomic chemotherapy following the maximum tolerated dose is an effective anti-tumour therapy affecting angiogenesis, tumour dissemination and cancer stem cells.

    Vives, Marta; Ginestà, Mireia M; Gracova, Kristina; Graupera, Mariona; Casanovas, Oriol; Capellà, Gabriel; Serrano, Teresa; Laquente, Berta; Viñals, Francesc


    In this article, the effectiveness of a multi-targeted chemo-switch (C-S) schedule that combines metronomic chemotherapy (MET) after treatment with the maximum tolerated dose (MTD) is reported. This schedule was tested with gemcitabine in two distinct human pancreatic adenocarcinoma orthotopic models and with cyclophosphamide in an orthotopic ovarian cancer model. In both models, the C-S schedule had the most favourable effect, achieving at least 80% tumour growth inhibition without increased toxicity. Moreover, in the pancreatic cancer model, although peritoneal metastases were observed in control and MTD groups, no dissemination was observed in the MET and C-S groups. C-S treatment caused a decrease in angiogenesis, and its effect on tumour growth was similar to that produced by the MTD followed by anti-angiogenic DC101 treatment. C-S treatment combined an increase in thrombospondin-1 expression with a decrease in the number of CD133+ cancer cells and triple-positive CD133+/CD44+/CD24+ cancer stem cells (CSCs). These findings confirm that the C-S schedule is a challenging clinical strategy with demonstrable inhibitory effects on tumour dissemination, angiogenesis and CSCs.

  14. Iron-based cathode catalyst with enhanced power density in polymer electrolyte membrane fuel cells.

    Proietti, Eric; Jaouen, Frédéric; Lefèvre, Michel; Larouche, Nicholas; Tian, Juan; Herranz, Juan; Dodelet, Jean-Pol


    H(2)-air polymer-electrolyte-membrane fuel cells are electrochemical power generators with potential vehicle propulsion applications. To help reduce their cost and encourage widespread use, research has focused on replacing the expensive Pt-based electrocatalysts in polymer-electrolyte-membrane fuel cells with a lower-cost alternative. Fe-based cathode catalysts are promising contenders, but their power density has been low compared with Pt-based cathodes, largely due to poor mass-transport properties. Here we report an iron-acetate/phenanthroline/zeolitic-imidazolate-framework-derived electrocatalyst with increased volumetric activity and enhanced mass-transport properties. The zeolitic-imidazolate-framework serves as a microporous host for phenanthroline and ferrous acetate to form a catalyst precursor that is subsequently heat treated. A cathode made with the best electrocatalyst from this work, tested in H(2)-O(2,) has a power density of 0.75 W cm(-2) at 0.6 V, a meaningful voltage for polymer-electrolyte-membrane fuel cells operation, comparable with that of a commercial Pt-based cathode tested under identical conditions.

  15. Research on improved maximum power point tracking method of photovoltaic cell array%光伏电池阵列改进MPPT控制方法研究

    张俊红; 魏学业; 谷建柱; 王立华


    In order to improve the conversion efficiency of photovoltaic cells, this paper proposed a improved variable step size and power prediction combined with perturbation and observation method based on the mathematic model of photovoltaic array, in view of the traditional fixed step perturbation and observation method which existed the oscillation phenomenon and false phenomenon to achieve maximum power point tracking. The oscillation and misjudgment problem was eliminated by using the approximate gradient method instead of optimal gradient method and using power prediction method of multiple characteristic curves estimated on the changes in the external environment. The algorithm theory and MATLAB simulation flow chart was given in the paper. The simulation results show that the algorithm can significantly improve the tracking precision and speed of MPPT.%为了提高光伏电池的转换效率,基于光伏阵列的数学模型,针对传统的定步长扰动观察法实现最大功率点跟踪(Maximum Power Point Tracking,MPPT)时,存在的振荡现象和误判现象,提出了一种改进的变步长与功率预测相结合的扰动观察法.通过采用近似梯度法替代最优梯度法,并对外界环境发生变化时,采用功率预测的方法对多条特性曲线进行预估,来消除震荡和误判问题.本文给出了该方法的理论推导和Matlab仿真实现流程图.仿真结果表明,该方法能够显著提高MPPT的跟踪精度和速度.

  16. Overexpression of LOXIN Protects Endothelial Progenitor Cells From Apoptosis Induced by Oxidized Low Density Lipoprotein.

    Veas, Carlos; Jara, Casandra; Willis, Naomi D; Pérez-Contreras, Karen; Gutierrez, Nicolas; Toledo, Jorge; Fernandez, Paulina; Radojkovic, Claudia; Zuñiga, Felipe A; Escudero, Carlos; Aguayo, Claudio


    Human endothelial progenitor cells (hEPC) are adult stem cells located in the bone marrow and peripheral blood. Studies have indicated that hEPC play an important role in the recovery and repair of injured endothelium, however, their quantity and functional capacity is reduced in several diseases including hypercholesterolemia. Recently, it has been demonstrated that hEPC express lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and its activation by oxidized low-density lipoprotein (ox-LDL) induces cellular dysfunction and apoptosis. This study aimed to investigate whether overexpression of LOXIN, a truncated isoform of LOX-1 that acts as a dominant negative, plays a protective role against ox-LDL-induced apoptosis in hEPC. Human endothelial progenitor cells exposed to ox-LDL showed a significant increase in LOX-1 expression, and apoptosis began at ox-LDL concentrations above 50 μg/mL. All hEPC apoptosed at 200 μg/mL ox-LDL. High LOXIN expression was generated using adenoviral systems in hEPC and SiHa cells transduced with 100 colony-forming units per cell. Transduced LOXIN localized to the plasma membrane and blocked ox-LDL uptake mediated by LOX-1. Overexpression of LOXIN protected hEPC from ox-LDL-induced apoptosis, and therefore maybe a novel way of improving hEPC function and quantity. These results suggest that adenoviral vectors of LOXIN may provide a possible treatment for diseases related to ox-LDL and vascular endothelium dysfunction, including atherosclerosis.

  17. Distribution and density of mast cells in camel small intestine and influence of fixation techniques

    MB Al-Zghoul


    Full Text Available This study was carried out to gather species-specific data on mast-cell density and distribution in camel small intestine under different fixation conditions and to elucidate the presence and cross-reactivity of tryptase in the camel small intestine using human specific anti-tryptase antibody. Tissue specimens from the jejunum, duodenum, and ileum were obtained from 9 healthy, 9-12 months old, male camels. Specimens were fixed either with carnoy’s fluid or formalinbuffered solution and stained with either methylene blue or immunohistochemically to identify mast cells. The present study demonstrated for the first time, the presence and cross-reactivity of tryptase in the camel small intestine using a specific mouse anti-human tryptase antibody. Mast cells were detected in all histological layers of the camel small intestine (mucosal, submucosal, muscularis externa and serosa. Among all locations examined in the duodenum, ileum and jejunum, no significant difference was observed in mast-cell counts among the lamina propria, muscularis mucosae, muscularis externa and the serosa. The only significant difference observed was the mast-cell count in submucosa region where the highest and lowest mast count was observed in the jejenual and ileal submucosa, respectively. Significant differences regarding the distribution of mast cell as well as the influence of the fixation method could be observed. This underlines the fact that data regarding mast cell heterogeneity from other species, obtained by different fixation methods, are not comparable. This fact has to be taken into account when evaluating mast cell subtypes under pathological conditions.

  18. Bile acids reduce endocytosis of high-density lipoprotein (HDL) in HepG2 cells.

    Röhrl, Clemens; Eigner, Karin; Fruhwürth, Stefanie; Stangl, Herbert


    High-density lipoprotein (HDL) transports lipids to hepatic cells and the majority of HDL-associated cholesterol is destined for biliary excretion. Cholesterol is excreted into the bile directly or after conversion to bile acids, which are also present in the plasma as they are effectively reabsorbed through the enterohepatic cycle. Here, we provide evidence that bile acids affect HDL endocytosis. Using fluorescent and radiolabeled HDL, we show that HDL endocytosis was reduced in the presence of high concentrations of taurocholate, a natural non-cell-permeable bile acid, in human hepatic HepG2 and HuH7 cells. In contrast, selective cholesteryl-ester (CE) uptake was increased. Taurocholate exerted these effects extracellularly and independently of HDL modification, cell membrane perturbation or blocking of endocytic trafficking. Instead, this reduction of endocytosis and increase in selective uptake was dependent on SR-BI. In addition, cell-permeable bile acids reduced HDL endocytosis by farnesoid X receptor (FXR) activation: chenodeoxycholate and the non-steroidal FXR agonist GW4064 reduced HDL endocytosis, whereas selective CE uptake was unaltered. Reduced HDL endocytosis by FXR activation was independent of SR-BI and was likely mediated by impaired expression of the scavenger receptor cluster of differentiation 36 (CD36). Taken together we have shown that bile acids reduce HDL endocytosis by transcriptional and non-transcriptional mechanisms. Further, we suggest that HDL endocytosis and selective lipid uptake are not necessarily tightly linked to each other.

  19. The importance of cell density in the interpretation of growth factor effects on collagenase IV activity release and extracellular matrix production from C6 astrocytoma cells.

    Tamaki, M; McDonald, W; Del Maestro, R F


    We have examined the influence of basic fibroblast growth factor (FGF-2) and vascular endothelial growth factor (VEGF) on the release of collagenase type IV activity and the production of extracellular matrix (ECM) molecules using C6 astrocytoma cells in monolayer culture. Collagenase type IV activity was significantly increased in a dose dependent manner in the low cell density group by treatment with FGF-2 and VEGF but significantly decreased in a dose dependent fashion in the high cell density group. These results were corroborated using Western blot technique with an antibody to gelatinase A. Addition of exogenous laminin and fibronectin to the media decreased collagenase type IV activity in a dose dependent fashion with the minimum concentration of 0.1 microgram/ml. Laminin and fibronectin reached a concentration of 0.1 microgram/ml in only the high cell density group after treatment with the growth factors tested. These findings indicate that C6 astrocytoma cells appear to have two regulatory mechanisms for collagenase type IV activity which are dependent on cell density. In a low cell density, C6 astrocytoma cells respond to the dominant effect of FGF-2 and VEGF by increasing the release of collagenase IV activity. In a high cell density collagenase type IV activity is decreased due to it's down regulation by released ECM molecules in response to FGF-2 and VEGF. These regulatory mechanisms may be crucial to the understanding of the coordination of tumor-associated angiogenesis by malignant glial cells.

  20. Interaction effects of cell diffusion, cell density and public goods properties on the evolution of cooperation in digital microbes.

    Dobay, A; Bagheri, H C; Messina, A; Kümmerli, R; Rankin, D J


    Microbial cooperation typically consists in the sharing of secreted metabolites (referred to as public goods) within the community. Although public goods generally promote population growth, they are also vulnerable to exploitation by cheating mutants, which no longer contribute, but still benefit from the public goods produced by others. Although previous studies have identified a number of key factors that prevent the spreading of cheaters, little is known about how these factors interact and jointly shape the evolution of microbial cooperation. Here, we address this issue by investigating the interaction effects of cell diffusion, cell density, public good diffusion and durability (factors known to individually influence costs and benefits of public goods production) on selection for cooperation. To be able to quantify these effects across a wide parameter space, we developed an individual-based simulation platform, consisting of digital cooperator and cheater bacteria inhabiting a finite two-dimensional continuous toroidal surface. Our simulations, which closely mimic microbial microcolony growth, revealed that: (i) either reduced cell diffusion (which keeps cooperators together) or reduced public good diffusion (which keeps the public goods closer to the producer) is not only essential but also sufficient for cooperation to be promoted; (ii) the sign of selection for or against cooperation can change as a function of cell density and in interaction with diffusion parameters; and (iii) increased public goods durability has opposing effects on the evolution of cooperation depending on the level of cell and public good diffusion. Our work highlights that interactions between key parameters of public goods cooperation give rise to complex fitness landscapes, a finding that calls for multifactorial approaches when studying microbial cooperation in natural systems.

  1. The influence of nutrient supply and cell density on the growth and survival of intervertebral disc cells in 3D culture

    S Stephan


    Full Text Available The adult human intervertebral disc (IVD is normally avascular. Changes to the extracellular matrix in degenerative disc disease may promote vascularisation and subsequently alter cell nutrition and disc homeostasis. This study examines the influence of cell density and the presence of glucose and serum on the proliferation and survival of IVD cells in 3D culture.Bovine nucleus pulposus (NP cells were seeded at a range of cell densities (1.25 x105-106 cells/mL and cultured in alginate beads under standard culture conditions (with 3.15 g/L glucose and 10 % serum, or without glucose and/or 20 % serum. Cell proliferation, apoptosis and cell senescence were examined after 8 days in culture.Under standard culture conditions, NP cell proliferation and cluster formation was inversely related to cell seeding density, whilst the number of apoptotic cells and enucleated “ghost” cells was positively correlated to cell seeding density. Increasing serum levels from 10 % to 20 % was associated with increased cluster size and also an increased prevalence of apoptotic cells within clusters. Omitting glucose produced even larger clusters and also more apoptotic and senescent cells. These studies demonstrate that NP cell growth and survival are influenced both by cell density and the availability of serum or nutrients, such as glucose. The observation of clustered, senescent, apoptotic or “ghost” cells in vitro suggests that environmental factors may influence the formation of these phenotypes that have been previously reported in vivo. Hence this study has implications for both our understanding of degenerative disc disease and also cell-based therapy using cells cultured in vitro.

  2. Circulating endothelial progenitor cells, microvascular density and fibrosis in obesity before and after bariatric surgery.

    De Ciuceis, Carolina; Rossini, Claudia; Porteri, Enzo; La Boria, Elisa; Corbellini, Claudia; Mittempergher, Francesco; Di Betta, Ernesto; Petroboni, Beatrice; Sarkar, Annamaria; Agabiti-Rosei, Claudia; Casella, Claudio; Nascimbeni, Riccardo; Rezzani, Rita; Rodella, Luigi F; Bonomini, Francesca; Agabiti-Rosei, Enrico; Rizzoni, Damiano


    It is not known whether, in obesity, the capillary density or the number of circulating endothelial progenitor cells (EPCs) are reduced, or whether fibrosis of small vessels is also present. In addition, possible effects of weight reduction on these parameters have never been evaluated. Therefore, we investigated EPCs and capillary density in 25 patients with severe obesity, all submitted to bariatric surgery, and in 18 normotensive lean subjects and 12 hypertensive lean patients as controls. All patients underwent a biopsy of subcutaneous fat during bariatric surgery. In five patients, a second biopsy was obtained after consistent weight loss, about 1 year later, during a surgical intervention for abdominoplasty. EPCs and capillary density were reduced in obesity, and EPCs were significantly increased after weight reduction. Vascular collagen content was clearly increased in obese patients. No significant difference in vascular collagen was observed between normotensive obese patients and hypertensive obese patients. After pronounced weight reduction, collagen content was nearly normalized. No difference in stress-strain relation was observed among groups or before and after weight loss. In conclusion, our data suggest that microvascular rarefaction occurs in obesity. EPCs were significantly reduced in obese patients. Pronounced weight loss induced by bariatric surgery seems to induce a significant improvement of EPC number, but not of capillary rarefaction. A pronounced fibrosis of subcutaneous small resistance arteries is present in obese patients, regardless of the presence of increased blood pressure values. Consistent weight loss induced by bariatric surgery may induce an almost complete regression of microvascular fibrosis.

  3. A high power density miniaturized microbial fuel cell having carbon nanotube anodes

    Ren, Hao; Pyo, Soonjae; Lee, Jae-Ik; Park, Tae-Jin; Gittleson, Forrest S.; Leung, Frederick C. C.; Kim, Jongbaeg; Taylor, André D.; Lee, Hyung-Sool; Chae, Junseok


    Microbial fuel cells (MFCs) are a promising technology capable of directly converting the abundant biomass on the planet into electricity. Prior studies have adopted a variety of nanostructured materials with high surface area to volume ratio (SAV), yet the current and power density of these nanostructured materials do not deliver a significant leap over conventional MFCs. This study presents a novel approach to implement a miniaturized MFC with a high SAV of 4000 m-1 using three different CNT-based electrode materials: Vertically Aligned CNT (VACNT), Randomly Aligned CNT (RACNT), and Spin-Spray Layer-by-Layer (SSLbL) CNT. These CNT-based electrodes show unique biofilm morphology and thickness. The study of performance parameters of miniaturized MFCs with these CNT-electrodes are conducted with respect to a control bare gold electrode. The results show that CNT-based materials attract more exoelectrogens, Geobacter sp., than bare gold, yielding thicker biofilm formation. Among CNT-based electrodes, low sheet resistance electrodes result in thick biofilm generation and high current/power density. The miniaturized MFC having an SSLbL CNT anode exhibits a high volumetric power density of 3320 W m-3. This research may help lay the foundation for future research involving the optimization of MFCS with 2D and 3D nanostructured electrodes.

  4. High short-circuit current density CdTe solar cells using all-electrodeposited semiconductors

    Echendu, O.K., E-mail:; Fauzi, F.; Weerasinghe, A.R.; Dharmadasa, I.M.


    CdS/CdTe and ZnS/CdTe n–n heterojunction solar cells have been fabricated using all-electrodeposited semiconductors. The best devices show remarkable high short-circuit current densities of 38.5 mAcm{sup −2} and 47.8 mAcm{sup −2}, open-circuit voltages of 630 mV and 646 mV and conversion efficiencies of 8.0% and 12.0% respectively. The major strength of these device structures lies in the combination of n–n heterojunction with a large Schottky barrier at the n-CdTe/metal back contact which provides the required band bending for the separation of photo-generated charge carriers. This is in addition to the use of a high quality n-type CdTe absorber layer with high electron mobility. The potential barrier heights estimated for these devices from the current–voltage characteristics exceed 1.09 eV and 1.13 eV for CdS/CdTe and ZnS/CdTe cells respectively. The diode rectification factors of both devices are in excess of four orders of magnitude with reverse saturation current densities of 1.0 × 10{sup −7} Acm{sup −2} and 4.0 × 10{sup −7} Acm{sup −2} respectively. These all-electrodeposited solar cell device structures are currently being studied and developed as an alternative to the well-known p–n junction structures which utilise chemical bath-deposited CdS. The preliminary material growth, device fabrication and assessment results are presented in this paper. - Highlights: • Two-electrode deposition. • High J{sub sc} Schottky barrier solar cells. • CdCl{sub 2} + CdF{sub 2} treatment.

  5. Ceruloplasmin enhances smooth muscle cell- and endothelial cell-mediated low density lipoprotein oxidation by a superoxide-dependent mechanism

    Mukhopadhyay, C. K.; Ehrenwald, E.; Fox, P. L.


    Cultured vascular smooth muscle cells (SMC) and endothelial cells (EC) stimulate low density lipoprotein (LDL) oxidation by free radical-mediated, transition metal-dependent mechanisms. The physiological source(s) of metal ions is not known; however, purified ceruloplasmin, a plasma protein containing 7 coppers, oxidizes LDL in vitro. We now show that ceruloplasmin also increases LDL oxidation by vascular cells. In metal ion-free medium, human ceruloplasmin increased bovine aortic SMC- and EC-mediated LDL oxidation by up to 30- and 15-fold, respectively. The maximal response was at 100-300 microg ceruloplasmin/ml, a level at or below the unevoked physiological plasma concentration. Oxidant activity was dependent on protein structure as a specific proteolytic cleavage or removal of one of the seven ceruloplasmin copper atoms inhibited activity. Three lines of evidence indicated a critical role for cellular superoxide (O2.) in ceruloplasmin-stimulated oxidation. First, the rate of production of O2. by cells correlated with their rates of LDL oxidation. Second, superoxide dismutase effectively blocked ceruloplasmin-stimulated oxidation by both cell types. Finally, O2. production by SMC quantitatively accounted for the observed rate of LDL oxidation. To show this, the course of O2. production by SMC was simulated by repeated addition of xanthine and xanthine oxidase to culture medium under cell-free conditions. Neither ceruloplasmin nor O2. alone increased LDL oxidation, but together they completely reconstituted the oxidation rate of ceruloplasmin-stimulated SMC. These results are the first to show that ceruloplasmin stimulates EC- and SMC-mediated oxidation of LDL and that cell-derived O2. accounts quantitatively for metal-dependent, free radical-initiated oxidation of LDL by these cells.

  6. Corneal endothelial cell density and morphology and central corneal thickness in Guangxi Maonan and Han adolescent students of China

    Hao; Liang; Hui-Yi; Zuo; Jin-Mao; Chen; Jie; Cai; Yu-Zhua; Qin; Yu-Ping; Huang; Ying-Ying; Chen; Dong-Yong; Tang; Shao-Jian; Tan


    AIM: To investigate the corneal endothelial cell density and morphology and central corneal thickness in the Guangxi Maonan and Han adolescent students of China.METHODS: Noncontact specular microscope(Topcon SP3000 P, Tokyo, Japan) was performed in 133 adolescent students of Maonan nationality(M:F 54:79)and 105 adolescent students of Han nationality(M:F 50:55),5 to 20 y of age, who were randomly selected from 3schools in Huanjiang Maonan Autonomous County of Guangxi Zhuang Autonomous Region of China.Parameters studied included endothelial cell density,mean cell area, coefficient of variation in cell size,percentage hexagonality and central corneal thickness. RESULTS: Endothelial cell density, mean cell area,coefficient of variation in cell size, percentage hexagonality and central corneal thickness in the study population were(2969.50 ±253.93) cells/mm2,(339.23 ±29.44) μm2,(29.96 ±4.07) %,(64.58 ±9.41) % and(523.71 ±32.82) μm in Maonan and(2998.26 ±262.65) cells/mm2,(336.11±30.07) μm2,(29.89±5.03) %,(64.91±11.64) % and(524.39 ±33.15) μm in Han, respectively. No significant differences were observed in endothelial cell density,mean cell area, coefficient of variation in cell size,percentage hexagonality and central corneal thickness between Maonan and Han(P =0.615, 0.659, 0.528, 0.551,0.999). In Maonan and Han, we found age was negatively correlated with endothelial cell density and percentagehexagonality and positively correlated with mean cell area and coefficient of variation in cell size. Negative correlation was also found between central corneal thickness and age in Han, whereas no correlation was found in Maonan. CONCLUSION: There were no differences between Maonan and Han in corneal endothelial cell density and morphology and central corneal thickness. In these two nationalities, there were statistically significant decrease in endothelial cell density and percentage hexagonality with increasing age and statistically significant increase in

  7. Kinetic modeling of rhamnolipid production by Pseudomonas aeruginosa PAO1 including cell density-dependent regulation.

    Henkel, Marius; Schmidberger, Anke; Vogelbacher, Markus; Kühnert, Christian; Beuker, Janina; Bernard, Thomas; Schwartz, Thomas; Syldatk, Christoph; Hausmann, Rudolf


    The production of rhamnolipid biosurfactants by Pseudomonas aeruginosa is under complex control of a quorum sensing-dependent regulatory network. Due to a lack of understanding of the kinetics applicable to the process and relevant interrelations of variables, current processes for rhamnolipid production are based on heuristic approaches. To systematically establish a knowledge-based process for rhamnolipid production, a deeper understanding of the time-course and coupling of process variables is required. By combining reaction kinetics, stoichiometry, and experimental data, a process model for rhamnolipid production with P. aeruginosa PAO1 on sunflower oil was developed as a system of coupled ordinary differential equations (ODEs). In addition, cell density-based quorum sensing dynamics were included in the model. The model comprises a total of 36 parameters, 14 of which are yield coefficients and 7 of which are substrate affinity and inhibition constants. Of all 36 parameters, 30 were derived from dedicated experimental results, literature, and databases and 6 of them were used as fitting parameters. The model is able to describe data on biomass growth, substrates, and products obtained from a reference batch process and other validation scenarios. The model presented describes the time-course and interrelation of biomass, relevant substrates, and products on a process level while including a kinetic representation of cell density-dependent regulatory mechanisms.

  8. Durability of Low Platinum Fuel Cells Operating at High Power Density

    Polevaya, Olga [Nuvera Fuel Cells Inc.; Blanchet, Scott [Nuvera Fuel Cells Inc.; Ahluwalia, Rajesh [Argonne National Lab; Borup, Rod [Los-Alamos National Lab; Mukundan, Rangachary [Los-Alamos National Lab


    Understanding and improving the durability of cost-competitive fuel cell stacks is imperative to successful deployment of the technology. Stacks will need to operate well beyond today’s state-of-the-art rated power density with very low platinum loading in order to achieve the cost targets set forth by DOE ($15/kW) and ultimately be competitive with incumbent technologies. An accelerated cost-reduction path presented by Nuvera focused on substantially increasing power density to address non-PGM material costs as well as platinum. The study developed a practical understanding of the degradation mechanisms impacting durability of fuel cells with low platinum loading (≤0.2mg/cm2) operating at high power density (≥1.0W/cm2) and worked out approaches for improving the durability of low-loaded, high-power stack designs. Of specific interest is the impact of combining low platinum loading with high power density operation, as this offers the best chance of achieving long-term cost targets. A design-of-experiments approach was utilized to reveal and quantify the sensitivity of durability-critical material properties to high current density at two levels of platinum loading (the more conventional 0.45–1 and the much lower 0.2–2) across several cell architectures. We studied the relevance of selected component accelerated stress tests (AST) to fuel cell operation in power producing mode. New stress tests (NST) were designed to investigate the sensitivity to the addition of electrical current on the ASTs, along with combined humidity and load cycles and, eventually, relate to the combined city/highway drive cycle. Changes in the cathode electrochemical surface area (ECSA) and average oxygen partial pressure on the catalyst layer with aging under AST and NST protocols were compared based on the number of completed cycles. Studies showed elevated sensitivity of Pt growth to the potential limits and the initial particle size distribution. The ECSA loss

  9. BDNF over-expression increases olfactory bulb granule cell dendritic spine density in vivo.

    McDole, B; Isgor, C; Pare, C; Guthrie, K


    Olfactory bulb granule cells (GCs) are axon-less, inhibitory interneurons that regulate the activity of the excitatory output neurons, the mitral and tufted cells, through reciprocal dendrodendritic synapses located on GC spines. These contacts are established in the distal apical dendritic compartment, while GC basal dendrites and more proximal apical segments bear spines that receive glutamatergic inputs from the olfactory cortices. This synaptic connectivity is vital to olfactory circuit function and is remodeled during development, and in response to changes in sensory activity and lifelong GC neurogenesis. Manipulations that alter levels of the neurotrophin brain-derived neurotrophic factor (BDNF) in vivo have significant effects on dendritic spine morphology, maintenance and activity-dependent plasticity for a variety of CNS neurons, yet little is known regarding BDNF effects on bulb GC spine maturation or maintenance. Here we show that, in vivo, sustained bulbar over-expression of BDNF in transgenic mice produces a marked increase in GC spine density that includes an increase in mature spines on their apical dendrites. Morphometric analysis demonstrated that changes in spine density were most notable in the distal and proximal apical domains, indicating that multiple excitatory inputs are potentially modified by BDNF. Our results indicate that increased levels of endogenous BDNF can promote the maturation and/or maintenance of dendritic spines on GCs, suggesting a role for this factor in modulating GC functional connectivity within adult olfactory circuitry.

  10. Enhanced current and power density of micro-scale microbial fuel cells with ultramicroelectrode anodes

    Ren, Hao; Rangaswami, Sriram; Lee, Hyung-Sool; Chae, Junseok


    We present a micro-scale microbial fuel cell (MFC) with an ultramicroelectrode (UME) anode, with the aim of creating a miniaturized high-current/power-density converter using carbon-neutral and renewable energy sources. Micro-scale MFCs have been studied for more than a decade, yet their current and power densities are still an order of magnitude lower than those of their macro-scale counterparts. In order to enhance the current/power densities, we engineer a concentric ring-shaped UME, with a width of 20 μm, to facilitate the diffusion of ions in the vicinity of the micro-organisms that form biofilm on the UME. The biofilm extends approximately 15 μm from the edge of the UME, suggesting the effective biofilm area increases. Measured current/power densities per the effective area and the original anode area are 7.08  ±  0.01 A m-2 & 3.09  ±  0.04 W m-2 and 17.7  ±  0.03 A m-2 & 7.72  ±  0.09 W m-2, respectively. This is substantially higher than any prior work in micro-scale MFCs, and very close, or even higher, to that of macro-scale MFCs. A Coulombic efficiency, a measure of how efficiently an MFC harvests electrons from donor substrate, of 70%, and an energy conversion efficiency of 17% are marked, highlighting the micro-scale MFC as an attractive alternative within the existing energy conversion portfolio.

  11. Feeding strategies enhance high cell density cultivation and protein expression in milliliter scale bioreactors.

    Faust, Georg; Janzen, Nils H; Bendig, Christoph; Römer, Lin; Kaufmann, Klaus; Weuster-Botz, Dirk


    Miniature bioreactors under parallel fed-batch operations are not only useful screening tools for bioprocess development but also provide a suitable basis for eventual scale-up. In this study, three feeding strategies were investigated: besides the established intermittent feeding by a liquid handler, an optimized microfluidic device and a new enzymatic release system were applied for parallel fed-batch cultivation of Escherichia coli HMS174(DE3) and BL21(DE3) strains in stirred-tank bioreactors on a 10 mL scale. Lower fluctuation in dissolved oxygen (DO) and higher optical densities were measured in fed-batch processes applying the microfluidic device or the enzymatic glucose/fructose release system (conversion of intermittently added sucrose by an invertase), but no difference in dry cell weights (DCW) were observed. With all three feeding strategies high cell densities were realized on a milliliter scale with final optical density measured at 600 nm (OD600 ) of 114-133 and final DCW concentrations of 69-70 g L(-1) . The effect of feeding strategies on the expression of two heterologous proteins was investigated. Whereas no impact was observed on the expression of the spider silk protein eADF4(C16), the fluorescence of enhanced green fluorescence protein (eGFP) was reproducibly lower, if an intermittent glucose feed was applied. Thus, the impact of feeding strategy on expression is strongly dependent on the E. coli strain and/or expressed protein. As a completely continuous feed supply is difficult to realize in miniature bioreactors, the enzymatic release approach from this study can be easily applied in all microfluidic system to reduce fluctuations of glucose supply and DO concentrations.

  12. [The receptor-mediated endocytosis of influenza viruses and low-density lipoproteins by tissue cells].

    Pleskov, V M; Bannikov, A I; Zaĭtsev, Iu V


    The experimental data obtained by immunological, immunomorphological, biochemical, and virological methods are presented which substantiate a concept that various strains of influenza virus under study may penetrate tissue cells at sites of high affinity usually meant for low-density lipoproteins (LDLP) providing the cells with cholesterol for construction of outer and inner membranes. A computer analysis of a bank of data on the primary structure of proteins (the package of GENBER programme) revealed significant similarity of amino acid sequences between the area of viral hemagglutinin site attachment to cells and corresponding amino acids comprising apoB LDLP. The presented proofs are a convincing example of virus particles mimicry realized at the molecular level and give new concepts concerning the mechanisms of virus penetration into body cells which are important for the development of a principally new approach to creation of highly effective antiviral compounds. Moreover, the observed phenomenon may serve for explanation of the nature and mechanism of action of the so-called thermostable virus-neutralizing blood serum inhibitor.

  13. Evaluation of mast cell counts and microvessel density in reactive lesions of the oral cavity

    Kouhsoltani, Maryam; Moradzadeh Khiavi, Monir; Tahamtan, Shabnam


    Background. Reliable immunohistochemical assays to assess the definitive role of mast cells (MCs) and angiogenesis in the pathogenesis of oral reactive lesions are generally not available. The aim of the present study was to evaluate mast cell counts (MCC) and microvessel density (MVD) in oral reactive lesions and determine the correlation between MCC and MVD. Methods. Seventy-five cases of reactive lesions of the oral cavity, including pyogenic granuloma, fibroma, peripheral giant cell granuloma, inflammatory fibrous hyperplasia, peripheral ossifying fibroma (15 for each category) were immunohisto-chemically stained with MC tryptase and CD31. Fifteen cases of normal gingival tissue were considered as the control group. The mean MCC and MVD in superficial and deep connective tissues were assessed and total MCC and MVD was computed for each lesion. Results. Statistically significant differences were observed in MCC and MVD between the study groups (P < 0.001). MC tryptase and CD31 expression increased in the superficial connective tissue of each lesion in comparison to the deep con-nective tissue. A significant negative correlation was not found between MCC and MVD in oral reactive lesions (P < 0.001, r = -0.458). Conclusion. Although MCs were present in the reactive lesions of the oral cavity, a direct correlation between MCC and MVD was not found in these lesions. Therefore, a significant interaction between MCs and endothelial cells and an active role for MCs in the growth of oral reactive lesions was not found in this study. PMID:28096950

  14. Metal based gas diffusion layers for enhanced fuel cell performance at high current densities

    Hussain, Nabeel; Van Steen, Eric; Tanaka, Shiro; Levecque, Pieter


    The gas diffusion layer strongly influences the performance and durability of polymer electrolyte fuel cells. A major drawback of current carbon fiber based GDLs is the non-controlled variation in porosity resulting in a random micro-structure. Moreover, when subjected to compression these materials show significant reduction in porosity and permeability leading to water management problems and mass transfer losses within the fuel cell. This study investigated the use of uniform perforated metal sheets as GDLs in conjunction with microchannel flowfields. A metal sheet design with a pitch of 110 μm and a hole diameter of 60 μm in combination with an MPL showed superior performance in the high current density region compared to a commercially available carbon paper based GDL in a single cell environment. Fuel cell testing with different oxidants (air, heliox and oxygen) indicate that the metal sheet offers both superior diffusion and reduced flooding in comparison to the carbon based GDL. The presence of the MPL has been found to be critical to the functionality of the metal sheet suggesting that the MPL design may represent an important optimisation parameter for further improvements in performance.

  15. T-cell activation: A queuing theory analysis at low agonist density.

    Wedagedera, J R; Burroughs, N J


    We analyze a simple linear triggering model of the T-cell receptor (TCR) within the framework of queuing theory, in which TCRs enter the queue upon full activation and exit by downregulation. We fit our model to four experimentally characterized threshold activation criteria and analyze their specificity and sensitivity: the initial calcium spike, cytotoxicity, immunological synapse formation, and cytokine secretion. Specificity characteristics improve as the time window for detection increases, saturating for time periods on the timescale of downregulation; thus, the calcium spike (30 s) has low specificity but a sensitivity to single-peptide MHC ligands, while the cytokine threshold (1 h) can distinguish ligands with a 30% variation in the complex lifetime. However, a robustness analysis shows that these properties are degraded when the queue parameters are subject to variation-for example, under stochasticity in the ligand number in the cell-cell interface and population variation in the cellular threshold. A time integration of the queue over a period of hours is shown to be able to control parameter noise efficiently for realistic parameter values when integrated over sufficiently long time periods (hours), the discrimination characteristics being determined by the TCR signal cascade kinetics (a kinetic proofreading scheme). Therefore, through a combination of thresholds and signal integration, a T cell can be responsive to low ligand density and specific to agonist quality. We suggest that multiple threshold mechanisms are employed to establish the conditions for efficient signal integration, i.e., coordinate the formation of a stable contact interface.

  16. 采用高山松最大密度重建川西高原1917-2002年夏季气温%Reconstruction of summer temperature variation from maximum density of alpine pine during 1917-2002 for west Sichuan Plateau, China

    吴普; 王丽丽; 邵雪梅


    Having analyzed the tree ring width and maximum latewood density of Pinus den-sata from west Sichuan, we obtained different climate information from tree-ring width and maximum latewood density chronology. The growth of tree ring width was responded princi-pally to the precipitation in current May, which might be influenced by the activity of southwest monsoon, whereas the maximum latewood density reflected summer temperature (June-September). According to the correlation relationship, a transfer function had been used to reconstruct summer temperature for the study area. The explained variance of re-construction is 51% (F=-52.099, p<0.0001). In the reconstruction series: before the 1930s, the climate was relatively cold, and relatively warm from 1930 to 1960, this trend was in accor-dance with the cold-warm period of the last 100 years, west Sichuan. Compared with Chengdu, the warming break point in west Sichuan is 3 years ahead of time, indicating that the Tibetan Plateau was more sensitive to temperature change. There was an evident sum-mer warming signal after 1983. Although the last 100-year running average of summer tem-perature in the 1990s was the maximum, the running average of the early 1990s was below the average line and it was cold summer, but summer drought occurred in the late 1990s.

  17. The interaction between human low density lipoproteins and bovine aortic endothelial cells. Measurements of membrane fluidity.

    Badea, M G; Sima, A; Jinga, V V; Hörer, O


    Bovine aortic endothelial cells in culture have been incubated with human low density lipoproteins (LDL) characterized in their cholesterol content. The incubation was done at different time intervals up to 72 h and various LDL concentrations. It began after endothelial cells had been starved for 24 h in lipoprotein deficient serum. The transfer of some LDL-components to endothelial cells plasmalemma was monitored by measurements of membrane fluidity. Namely, the fluorescent probe trimethylamonio-diphenyl hexatriene was inserted in the cell membrane and fluorescence anisotropy was determined; a higher fluorescence anisotropy means a higher rigidity of the plasmalemma. The results show that the rigidity of the endothelial cell plasmalemma increased progressively with the time of incubation (+11% to +19.5% after 24 h and 72 h, respectively for the concentration of 200 micrograms. LDL-cholesterol/dish) and with the greater amount of cholesterol in LDL (+10.9%) for 200 micrograms LDL-cholesterol/dish to +15% for 800 micrograms LDL-cholesterol/dish after 24 h incubation). In order to see if the LDL material transfer proceeded by receptor-mediated endocytosis of LDL and/or directly through aqueous solution a lysosomal inhibitor, chloroquine, was used at the concentration of 20 microM for preventing the lysosomal hydrolase activity. In the presence of this inhibitor the fluorescence anisotropy in treated endothelial cells increased by a lesser amount, suggesting an approx. 30% participation of intracellular route. Therefore, the transfer of material (probably cholesterol) from LDL to endothelial plasmalemma could take place both by receptor-mediated endocytosis and directly through the aqueous solution.

  18. Decreased lung carcinoma cell density on select polymer nanometer surface features for lung replacement therapies

    Lijuan Zhang


    Full Text Available Lijuan Zhang1, Young Wook Chun2, Thomas J Webster21Department of Chemistry and 2Division of Engineering, Brown University, Providence, RI USAAbstract: Poly(lactic-co-glycolic acid (PLGA has been widely used as a biomaterial in regenerative medicine because of its biocompatibility and biodegradability properties. Previous studies have shown that cells (such as bladder smooth muscle cells, chondrocytes, and osteoblasts respond differently to nanostructured PLGA surfaces compared with nanosmooth surfaces. The purpose of the present in vitro research was to prepare PLGA films with various nanometer surface features and determine whether lung cancer epithelial cells respond differently to such topographies. To create nanosurface features on PLGA, different sized (190 nm, 300 nm, 400 nm, and 530 nm diameter polystyrene beads were used to cast polydimethylsiloxane (PDMS molds which were used as templates to create nanofeatured PLGA films. Atomic force microscopy (AFM images and root mean square roughness (RMS values indicated that the intended spherical surface nanotopographies on PLGA with RMS values of 2.23, 5.03, 5.42, and 36.90 nm were formed by employing 190, 300, 400, and 530 nm beads. A solution evaporation method was also utilized to modify PLGA surface features by using 8 wt% (to obtain an AFM RMS value of 0.62 nm and 4 wt% (to obtain an AFM RMS value of 2.23 nm PLGA in chloroform solutions. Most importantly, lung cancer epithelial cells adhered less on the PLGA surfaces with RMS values of 0.62, 2.23, and 5.42 nm after four hours of culture compared with any other PLGA surface created here. After three days, PLGA surfaces with an RMS value of 0.62 nm had much lower cell density than any other sample. In this manner, PLGA with specific nanometer surface features may inhibit lung cancer cell density which may provide an important biomaterial for the treatment of lung cancer (from drug delivery to regenerative medicine.Keywords: nanotechnology

  19. A more appropriate white blood cell count for estimating malaria parasite density in Plasmodium vivax patients in northeastern Myanmar.

    Liu, Huaie; Feng, Guohua; Zeng, Weilin; Li, Xiaomei; Bai, Yao; Deng, Shuang; Ruan, Yonghua; Morris, James; Li, Siman; Yang, Zhaoqing; Cui, Liwang


    The conventional method of estimating parasite densities employ an assumption of 8000 white blood cells (WBCs)/μl. However, due to leucopenia in malaria patients, this number appears to overestimate parasite densities. In this study, we assessed the accuracy of parasite density estimated using this assumed WBC count in eastern Myanmar, where Plasmodium vivax has become increasingly prevalent. From 256 patients with uncomplicated P. vivax malaria, we estimated parasite density and counted WBCs by using an automated blood cell counter. It was found that WBC counts were not significantly different between patients of different gender, axillary temperature, and body mass index levels, whereas they were significantly different between age groups of patients and the time points of measurement. The median parasite densities calculated with the actual WBC counts (1903/μl) and the assumed WBC count of 8000/μl (2570/μl) were significantly different. We demonstrated that using the assumed WBC count of 8000 cells/μl to estimate parasite densities of P. vivax malaria patients in this area would lead to an overestimation. For P. vivax patients aged five years and older, an assumed WBC count of 5500/μl best estimated parasite densities. This study provides more realistic assumed WBC counts for estimating parasite densities in P. vivax patients from low-endemicity areas of Southeast Asia.

  20. Common pediatric cerebellar tumors: correlation between cell densities and apparent diffusion coefficient metrics.

    Koral, Korgün; Mathis, Derek; Gimi, Barjor; Gargan, Lynn; Weprin, Bradley; Bowers, Daniel C; Margraf, Linda


    To test whether there is correlation between cell densities and apparent diffusion coefficient (ADC) metrics of common pediatric cerebellar tumors. This study was reviewed for issues of patient safety and confidentiality and was approved by the Institutional Review Board of the University of Texas Southwestern Medical Center and was compliant with HIPAA. The need for informed consent was waived. Ninety-five patients who had preoperative magnetic resonance imaging and surgical pathologic findings available between January 2003 and June 2011 were included. There were 37 pilocytic astrocytomas, 34 medulloblastomas (23 classic, eight desmoplastic-nodular, two large cell, one anaplastic), 17 ependymomas (13 World Health Organization [WHO] grade II, four WHO grade III), and seven atypical teratoid rhabdoid tumors. ADCs of solid tumor components and normal cerebellum were measured. Tumor-to-normal brain ADC ratios (hereafter, ADC ratio) were calculated. The medulloblastomas and ependymomas were subcategorized according to the latest WHO classification, and tumor cellularity was calculated. Correlation was sought between cell densities and mean tumor ADCs, minimum tumor ADCs, and ADC ratio. When all tumors were considered together, negative correlation was found between cellularity and mean tumor ADCs (ρ = -0.737, P correlation between cellularity and ADC ratio. Negative correlation was found between cellularity and minimum tumor ADC in atypical teratoid rhabdoid tumors (ρ = -0.786, P correlation was found between cellularity and mean tumor ADC and ADC ratio. There was no correlation between the ADC metrics and cellularity of the pilocytic astrocytomas, medulloblastomas, and ependymomas. Negative correlation was found between cellularity and ADC metrics of common pediatric cerebellar tumors. Although ADC metrics are useful in the preoperative diagnosis of common pediatric cerebellar tumors and this utility is generally attributed to differences in cellularity of tumors

  1. Maximum Autocorrelation Factorial Kriging

    Nielsen, Allan Aasbjerg; Conradsen, Knut; Pedersen, John L.; Steenfelt, Agnete


    This paper describes maximum autocorrelation factor (MAF) analysis, maximum autocorrelation factorial kriging, and its application to irregularly sampled stream sediment geochemical data from South Greenland. Kriged MAF images are compared with kriged images of varimax rotated factors from an ordinary non-spatial factor analysis, and they are interpreted in a geological context. It is demonstrated that MAF analysis contrary to ordinary non-spatial factor analysis gives an objective discrimina...

  2. Chromogranin A cell density in the large intestine of Asian and European patients with irritable bowel syndrome.

    El-Salhy, Magdy; Patcharatrakul, Tanisa; Hatlebakk, Jan Gunnar; Hausken, Trygve; Gilja, Odd Helge; Gonlachanvit, Sutep

    Patients with irritable bowel syndrome (IBS) in Asia show distinctive differences from those in the western world. The gastrointestinal endocrine cells appear to play an important role in the pathophysiology of IBS. The present study aimed at studying the density of chromogranin A (CgA) cells in the large intestine of Thai and Norwegian IBS patients. Thirty Thai IBS patients and 20 control subjects, and 47 Norwegian IBS patients and 20 control subjects were included. A standard colonoscopy was performed in both the patients and controls, and biopsy samples were taken from the colon and the rectum. The biopsy samples were stained with hematoxylin-eosin and immunostained for CgA. The density of CgA cells was determined by computerized image analysis. In the colon and rectum, the CgA cell densities were far higher in both IBS and healthy Thai subjects than in Norwegians. The colonic CgA cell density was lower in Norwegian IBS patients than in controls, but did not differ between Thai IBS patients and controls. In the rectum, the CgA cell densities in both Thai and Norwegian patients did not differ from those of controls. The higher densities of CgA cells in Thai subjects than Norwegians may be explained by a higher exposure to infections at childhood and the development of a broad immune tolerance, by differences in the intestinal microbiota, and/or differing diet habits. The normal CgA cell density in Thai IBS patients in contrast to that of Norwegians may be due to differences in pathophysiology.

  3. Cell Density Effects of Frog Skin Bacteria on Their Capacity to Inhibit Growth of the Chytrid Fungus, Batrachochytrium dendrobatidis.

    Yasumiba, Kiyomi; Bell, Sara; Alford, Ross


    Bacterial symbionts on frog skin can reduce the growth of the chytrid fungus Batrachochytrium dendrobatidis (Bd) through production of inhibitory metabolites. Bacteria can be effective at increasing the resistance of amphibians to chytridiomycosis when added to amphibian skin, and isolates can be screened for production of metabolites that inhibit Bd growth in vitro. However, some bacteria use density-dependent mechanism such as quorum sensing to regulate metabolite production. It is therefore important to consider cell density effects when evaluating bacteria as possible candidates for bioaugmentation. The aim of our study was to evaluate how the density of cutaneous bacteria affects their inhibition of Bd growth in vitro. We sampled cutaneous bacteria isolated from three frog species in the tropical rainforests of northern Queensland, Australia, and selected ten isolates that were inhibitory to Bd in standardised pilot trials. We grew each isolate in liquid culture at a range of initial dilutions, sub-sampled each dilution at a series of times during the first 48 h of growth and measured spectrophotometric absorbance values, cell counts and Bd-inhibitory activity of cell-free supernatants at each time point. The challenge assay results clearly demonstrated that the inhibitory effects of most isolates were density dependent, with relatively low variation among isolates in the minimum cell density needed to inhibit Bd growth. We suggest the use of minimum cell densities and fast-growing candidate isolates to maximise bioaugmentation efforts.

  4. Alcohol dependence-related increase of glial cell density in the anterior cingulate cortex of suicide completers.

    Hercher, Christa; Parent, Martin; Flores, Cecilia; Canetti, Lilian; Turecki, Gustavo; Mechawar, Naguib


    Suicide is the most serious consequence of major depressive disorder (MDD). Although the anterior cingulate cortex (ACC; Brodmann area [BA] 24) has been increasingly investigated for its role in the etiology of MDD, there is surprisingly very little information about the possible implication of this brain region in suicide. We hypothesized that changes in BA24 cell densities occur in depressed individuals who commit suicide, possibly reflecting an altered state of cortical plasticity that is thought to occur in depression. We investigated cell densities and sizes in BA24 among suicide completers and matched sudden-death controls. We examined a 1-cm(3) tissue block from BA24a of the supracallosal ACC in 26 human postmortem brain specimens (13 depressed individuals who committed suicide and 13 controls). We assessed neuronal and glial cell densities as well as neuronal soma sizes in the upper and lower cortical layers using optical fractionator and nucleator 3-dimensional stereological probes. Glial densities, neuronal densities and soma sizes measured in BA24a did not differ significantly between controls and suicide completers. Secondary analyses showed a significant and robust increase in glial cell densities in BA24a of alcohol-dependent depressed suicide completers compared with depressed suicide completers who were not alcohol-dependent (38%) and, to a lesser extent, controls (30%). Our study, conducted with tissue samples from men only, made use of a nonspecific stain that does not distinguish between neuronal or glial cell subtypes. Furthermore, the quantitative analysis concerned upper and lower cortical contours rather than individual cortical layers. Our results indicate that in BA24, glial density, neuronal density and soma size are not affected in MDD and suicide. They also suggest that alcohol dependence has an important influence on glial densities in this key limbic structure.

  5. Alcohol dependence–related increase of glial cell density in the anterior cingulate cortex of suicide completers

    Hercher, Christa; Parent, Martin; Flores, Cecilia; Canetti, Lilian; Turecki, Gustavo; Mechawar, Naguib


    Background Suicide is the most serious consequence of major depressive disorder (MDD). Although the anterior cingulate cortex (ACC; Brodmann area [BA] 24) has been increasingly investigated for its role in the etiology of MDD, there is surprisingly very little information about the possible implication of this brain region in suicide. We hypothesized that changes in BA24 cell densities occur in depressed individuals who commit suicide, possibly reflecting an altered state of cortical plasticity that is thought to occur in depression. Methods We investigated cell densities and sizes in BA24 among suicide completers and matched sudden-death controls. We examined a 1-cm3 tissue block from BA24a of the supracallosal ACC in 26 human postmortem brain specimens (13 depressed individuals who committed suicide and 13 controls). We assessed neuronal and glial cell densities as well as neuronal soma sizes in the upper and lower cortical layers using optical fractionator and nucleator 3-dimensional stereological probes. Results Glial densities, neuronal densities and soma sizes measured in BA24a did not differ significantly between controls and suicide completers. Secondary analyses showed a significant and robust increase in glial cell densities in BA24a of alcohol-dependent depressed suicide completers compared with depressed suicide completers who were not alcohol-dependent (38%) and, to a lesser extent, controls (30%). Limitations Our study, conducted with tissue samples from men only, made use of a nonspecific stain that does not distinguish between neuronal or glial cell subtypes. Furthermore, the quantitative analysis concerned upper and lower cortical contours rather than individual cortical layers. Conclusion Our results indicate that in BA24, glial density, neuronal density and soma size are not affected in MDD and suicide. They also suggest that alcohol dependence has an important influence on glial densities in this key limbic structure. PMID:19568479

  6. Optimization of operating parameters to maximize the current density without flooding at the cathode membrane interface of a PEM fuel cell using Taguchi method and genetic algorithm

    S.S.L. Rao, A. Shaija, S. Jayaraj


    Full Text Available A mathematical model was developed to investigate water accumulation at the cathode membrane interface by varying different operating parameters like fuel cell operating temperature and pressure, cathode and anode humidification temperatures and cathode stoichiometry. Taguchi optimization methodology is then combined with this model to determine the optimal combination of the operating parameters to maximize current density without flooding. Results of analysis of variance (ANOVA show that fuel cell operating temperature and cathode humidification temperature are the two most significant parameters in the ratio of 56.07% and 27.89% respectively and also that higher fuel cell temperature and lower cathode humidification temperature are favourable to get the maximum current draw without flooding at the cathode membrane interface. The global optimum value of the operating parameters to maximize the current density without flooding was obtained by formulating as an optimization problem using genetic algorithm (GA. These results were compared with the results obtained using Taguchi method and it was found to be similar and slightly better.

  7. Oxidized low density lipoprotein (LDL) affects hyaluronan synthesis in human aortic smooth muscle cells.

    Viola, Manuela; Bartolini, Barbara; Vigetti, Davide; Karousou, Evgenia; Moretto, Paola; Deleonibus, Sara; Sawamura, Tatsuya; Wight, Thomas N; Hascall, Vincent C; De Luca, Giancarlo; Passi, Alberto


    Thickening of the vessel in response to high low density lipoprotein(s) (LDL) levels is a hallmark of atherosclerosis, characterized by increased hyaluronan (HA) deposition in the neointima. Human native LDL trapped within the arterial wall undergoes modifications such as oxidation (oxLDL). The aim of our study is to elucidate the link between internalization of oxLDL and HA production in vitro, using human aortic smooth muscle cells. LDL were used at an effective protein concentration of 20-50 μg/ml, which allowed 80% cell viability. HA content in the medium of untreated cells was 28.9 ± 3.7 nmol HA-disaccharide/cell and increased after oxLDL treatment to 53.9 ± 5.6. OxLDL treatments doubled the transcripts of HA synthase HAS2 and HAS3. Accumulated HA stimulated migration of aortic smooth muscle cells and monocyte adhesiveness to extracellular matrix. The effects induced by oxLDL were inhibited by blocking LOX-1 scavenger receptor with a specific antibody (10 μg/ml). The cholesterol moiety of LDL has an important role in HA accumulation because cholesterol-free oxLDL failed to induce HA synthesis. Nevertheless, cholesterol-free oxLDL and unmodified cholesterol (20 μg/ml) induce only HAS3 transcription, whereas 22,oxysterol affects both HAS2 and HAS3. Moreover, HA deposition was associated with higher expression of endoplasmic reticulum stress markers (CHOP and GRP78). Our data suggest that HA synthesis can be induced in response to specific oxidized sterol-related species delivered through oxLDL.

  8. Decreased pCO(2) accumulation by eliminating bicarbonate addition to high cell-density cultures.

    Goudar, Chetan T; Matanguihan, Ricaredo; Long, Edward; Cruz, Christopher; Zhang, Chun; Piret, James M; Konstantinov, Konstantin B


    High-density perfusion cultivation of mammalian cells can result in elevated bioreactor CO(2) partial pressure (pCO(2)), a condition that can negatively influence growth, metabolism, productivity, and protein glycosylation. For BHK cells in a perfusion culture at 20 x 10(6) cells/mL, the bioreactor pCO(2) exceeded 225 mm Hg with approximate contributions of 25% from cellular respiration, 35% from medium NaHCO(3), and 40% from NaHCO(3) added for pH control. Recognizing the limitations to the practicality of gas sparging for CO(2) removal in perfusion systems, a strategy based on CO(2) reduction at the source was investigated. The NaHCO(3) in the medium was replaced with a MOPS-Histidine buffer, while Na(2)CO(3) replaced NaHCO(3) for pH control. These changes resulted in 63-70% pCO(2) reductions in multiple 15 L perfusion bioreactors, and were reproducible at the manufacturing-scale. Bioreactor pCO(2) values after these modifications were in the 68-85 mm Hg range, pCO(2) reductions consistent with those theoretically expected. Low bioreactor pCO(2) was accompanied by both 68-123% increased growth rates and 58-92% increased specific productivity. Bioreactor pCO(2) reduction and the resulting positive implications for cell growth and productivity were brought about by process changes that were readily implemented and robust. This philosophy of pCO(2) reduction at the source through medium and base modification should be readily applicable to large-scale fed-batch cultivation of mammalian cells.

  9. High density lipoprotein (HDL promotes glucose uptake in adipocytes and glycogen synthesis in muscle cells.

    Qichun Zhang

    Full Text Available BACKGROUND: High density lipoprotein (HDL was reported to decrease plasma glucose and promote insulin secretion in type 2 diabetes patients. This investigation was designed to determine the effects and mechanisms of HDL on glucose uptake in adipocytes and glycogen synthesis in muscle cells. METHODS AND RESULTS: Actions of HDL on glucose uptake and GLUT4 translocation were assessed with 1-[(3H]-2-deoxyglucose and plasma membrane lawn, respectively, in 3T3-L1 adipocytes. Glycogen analysis was performed with amyloglucosidase and glucose oxidase-peroxidase methods in normal and palmitate-treated L6 cells. Small interfering RNA was used to observe role of scavenger receptor type I (SR-BI in glucose uptake of HDL. Corresponding signaling molecules were detected by immunoblotting. HDL stimulated glucose uptake in a time- and concentration-dependent manner in 3T3-L1 adipocytes. GLUT4 translocation was significantly increased by HDL. Glycogen deposition got enhanced in L6 muscle cells paralleling with elevated glycogen synthase kinase3 (GSK3 phosphorylation. Meanwhile, increased phosphorylations of Akt-Ser473 and AMP activated protein kinase (AMPK α were detected in 3T3-L1 adipocytes. Glucose uptake and Akt-Ser473 activation but not AMPK-α were diminished in SR-BI knock-down 3T3-L1 cells. CONCLUSIONS: HDL stimulates glucose uptake in 3T3-L1 adipocytes through enhancing GLUT4 translocation by mechanisms involving PI3K/Akt via SR-BI and AMPK signaling pathways, and increases glycogen deposition in L6 muscle cells through promoting GSK3 phosphorylation.

  10. Differential satellite cell density of type I and II fibres with lifelong endurance running in old men

    Mackey, Abigail; Karlsen, A; Couppé, C


    between these variables were determined. RESULTS: In O-Un and O-Tr, type II fibres were smaller and contained fewer satellite cells than type I fibres. However, when expressed relative to fibre area, the difference in satellite cell content between fibre types was eliminated in O-Tr, but not O...... the satellite cell pool and (ii) is associated with a similar density of satellite cells in type I and II fibres despite a failure to preserve the equal fibre type distribution of satellite cells observed in young individuals. Taken together, these data reveal a differential regulation of satellite cell content...

  11. Influence of oxidized low-density lipoproteins (LDL) on the viability of osteoblastic cells.

    Brodeur, Mathieu R; Brissette, Louise; Falstrault, Louise; Ouellet, Pascale; Moreau, Robert


    Cardiovascular diseases have recently been noted as potential risk factors for osteoporosis development. Although it is poorly understood how these two pathologies are related, it is a known fact that oxidized low-density lipoproteins (OxLDL) constitute potential determinants for both of them. The current study investigated the metabolism of OxLDL by osteoblasts and its effect on osteoblastic viability. The results obtained show that OxLDL are internalized but not degraded by osteoblasts while they can selectively transfer their CE to these cells. It is also demonstrated that OxLDL induce proliferation at low concentrations but cell death at high concentrations. This reduction of osteoblast viability was associated with lysosomal membrane damage caused by OxLDL as demonstrated by acridine orange relocalization. Accordingly, chloroquine, an inhibitor of lysosomal activity, accentuated cell death induced by OxLDL. Finally, we demonstrate that osteoblasts have the capacity to oxidize LDL and thereby potentially increase the local concentration of OxLDL. Overall, the current study confirms the potential role of OxLDL in the development of osteoporosis given its influence on osteoblastic viability.

  12. Automated computation of arbor densities: a step toward identifying neuronal cell types.

    Sümbül, Uygar; Zlateski, Aleksandar; Vishwanathan, Ashwin; Masland, Richard H; Seung, H Sebastian


    The shape and position of a neuron convey information regarding its molecular and functional identity. The identification of cell types from structure, a classic method, relies on the time-consuming step of arbor tracing. However, as genetic tools and imaging methods make data-driven approaches to neuronal circuit analysis feasible, the need for automated processing increases. Here, we first establish that mouse retinal ganglion cell types can be as precise about distributing their arbor volumes across the inner plexiform layer as they are about distributing the skeletons of the arbors. Then, we describe an automated approach to computing the spatial distribution of the dendritic arbors, or arbor density, with respect to a global depth coordinate based on this observation. Our method involves three-dimensional reconstruction of neuronal arbors by a supervised machine learning algorithm, post-processing of the enhanced stacks to remove somata and isolate the neuron of interest, and registration of neurons to each other using automatically detected arbors of the starburst amacrine interneurons as fiducial markers. In principle, this method could be generalizable to other structures of the CNS, provided that they allow sparse labeling of the cells and contain a reliable axis of spatial reference.

  13. Automated computation of arbor densities: a step toward identifying neuronal cell types

    Uygar eSümbül


    Full Text Available The shape and position of a neuron convey information regarding its molecular and functional identity. The identification of cell types from structure, a classic method, relies on the time-consuming step of arbor tracing. However, as genetic tools and imaging methods make data-driven approaches to neuronal circuit analysis feasible, the need for automated processing increases. Here, we first establish that mouse retinal ganglion cell types can be as precise about distributing their arbor volumes across the inner plexiform layer as they are about distributing the skeletons of the arbors. Then, we describe an automated approach to computing the spatial distribution of the dendritic arbors, or arbor density, with respect to a global depth coordinate based on this observation. Our method involves three-dimensional reconstruction of neuronal arbors by a supervised machine learning algorithm, post-processing of the enhanced stacks to remove somata and isolate the neuron of interest, and registration of neurons to each other using automatically detected arbors of the starburst amacrine interneurons as fiducial markers. In principle, this method could be generalizable to other structures of the CNS, provided that they allow sparse labeling of the cells and contain a reliable axis of spatial reference.

  14. Impact of Pancreatic Rat Islet Density on Cell Survival during Hypoxia

    A. Rodriguez-Brotons


    Full Text Available In bioartificial pancreases (BP, the number of islets needed to restore normoglycaemia in the diabetic patient is critical. However, the confinement of a high quantity of islets in a limited space may impact islet survival, particularly in regard to the low oxygen partial pressure (PO2 in such environments. The aim of the present study was to evaluate the impact of islet number in a confined space under hypoxia on cell survival. Rat islets were seeded at three different concentrations (150, 300, and 600 Islet Equivalents (IEQ/cm2 and cultured in normal atmospheric pressure (160 mmHg as well as hypoxic conditions (15 mmHg for 24 hours. Cell viability, function, hypoxia-induced changes in gene expression, and cytokine secretion were then assessed. Notably, hypoxia appeared to induce a decrease in viability and increasing islet density exacerbated the observed increase in cellular apoptosis as well as the loss of function. These changes were also associated with an increase in inflammatory gene transcription. Taken together, these data indicate that when a high number of islets are confined to a small space under hypoxia, cell viability and function are significantly impacted. Thus, in order to improve islet survival in this environment during transplantation, oxygenation is of critical importance.

  15. Whole-cell analysis of low-density lipoprotein uptake by macrophages using STEM tomography.

    Jean-Pierre Baudoin

    Full Text Available Nanoparticles of heavy materials such as gold can be used as markers in quantitative electron microscopic studies of protein distributions in cells with nanometer spatial resolution. Studying nanoparticles within the context of cells is also relevant for nanotoxicological research. Here, we report a method to quantify the locations and the number of nanoparticles, and of clusters of nanoparticles inside whole eukaryotic cells in three dimensions using scanning transmission electron microscopy (STEM tomography. Whole-mount fixed cellular samples were prepared, avoiding sectioning or slicing. The level of membrane staining was kept much lower than is common practice in transmission electron microscopy (TEM, such that the nanoparticles could be detected throughout the entire cellular thickness. Tilt-series were recorded with a limited tilt-range of 80° thereby preventing excessive beam broadening occurring at higher tilt angles. The 3D locations of the nanoparticles were nevertheless determined with high precision using computation. The obtained information differed from that obtained with conventional TEM tomography data since the nanoparticles were highlighted while only faint contrast was obtained on the cellular material. Similar as in fluorescence microscopy, a particular set of labels can be studied. This method was applied to study the fate of sequentially up-taken low-density lipoprotein (LDL conjugated to gold nanoparticles in macrophages. Analysis of a 3D reconstruction revealed that newly up-taken LDL-gold was delivered to lysosomes containing previously up-taken LDL-gold thereby forming onion-like clusters.

  16. Influence of cations and anions on the induction of cell density-independent luminescence in Photorhabdus luminescens.

    Tabei, Yosuke; Ogawa, Akane; Era, Mariko; Ninomiya, Junko; Morita, Hiroshi


    Bioluminescence is emitted by various living organisms, including bacteria. While the induction mechanism in marine luminescent bacteria, such as Vibrio fischeri and V. harveyi, has been well characterized, this mechanism has not been studied in detail in the non-marine luminescent bacterium Photorhabdus luminescens. Therefore, we investigated the effect of cations and anions on the induction of luminescence by P. luminescens. Cultivation of cells in an inorganic salts solution (ISS) containing KCl, CaCl2 , MgCl2 , NaHCO3 , and MgSO4 resulted in a rapid increase in luminescence intensity. Moreover, the induction of luminescence in the ISS medium was not dependent on cell density, since cell densities remained unchanged during 48 h. Furthermore, we found that compounds containing K(+) , Mg(2+) , and HCO3(-) were necessary to induce cell density-independent luminescence. The intensity of luminescence per cell cultured in medium containing KCl, MgCl2 , and NaHCO3 was approximately 100-fold higher than that cultured in NB. In contrast, when cells actively grew in normal growth condition, the intensity of luminescence per cell was not increased even in the presence of K(+) , Mg(2+) , and HCO3(-) . Thus, these results suggest that the luminescence of P. luminescens is regulated by 2 independent cell density-dependent and -independent mechanisms.

  17. Is there any maximum standardized uptake value variation among positron emission tomography scanners for mediastinal staging in non-small cell lung cancer?

    Iskender, Ilker; Kadioglu, Salih Zeki; Kosar, Altug; Atasalihi, Ali; Kir, Altan


    The maximum standardized uptake value (SUV(max)) varies among positron emission tomography-integrated computed tomography (PET/CT) centers in the staging of non-small cell lung cancer. We evaluated the ratio of the optimum SUV(max) cut-off for the lymph nodes to the median SUV(max) of the primary tumor (ratioSUV(max)) to determine SUV(max) variations between PET/CT scanners. The previously described PET predictive ratio (PPR) was also evaluated. PET/CT and mediastinoscopy and/or thoracotomy were performed on 337 consecutive patients between September 2005 and March 2009. Thirty-six patients were excluded from the study. The pathological results were correlated with the PET/CT findings. Histopathological examination was performed on 1136 N2 lymph nodes using 10 different PET/CT centers. The majority of patients (group A: 240) used the same PET/CT scanner at four different centers. Others patients were categorized as group B. The ratioSUV(max) for groups A and B was 0.18 and 0.22, respectively. The same ratio for centers 1, 2, 3 and 4 was 0.2, 0.21, 0.21, and 0.23, respectively. The optimal cut-off value of the PPR to predict mediastinal lymph node pathology for malignancy was 0.49 (likelihood ratio +2.02; sensitivity 70%, specificity 65%). We conclude that the ratioSUV(max) was similar for different scanners. Thus, SUV(max) is a valuable cut-off for comparing-centers.

  18. Maximum standardized uptake value on PET/CT in preoperative assessment of lymph node metastasis from thoracic esophageal squamous cell carcinoma

    Amos JM Ela Bella; Ya-Rui Zhang; Wei Fan; Kong-Jia Luo; Tie-Hua Rong; Peng Lin; Hong Yang; Jian-Hua Fu


    The presence of lymph node metastasis is an important prognostic factor for patients with esophageal cancer. Accurate assessment of lymph nodes in thoracic esophageal carcinoma is essential for selecting appropriate treatment and forecasting disease progression. Positron emission tomography combined with computed tomography (PET/CT) is becoming an important tool in the workup of esophageal carcinoma. Here, we evaluated the effectiveness of the maximum standardized uptake value (SUVmax) in assessing lymph node metastasis in esophageal squamous cell carcinoma (ESCC) prior to surgery. Fifty-nine surgical patients with pathologically confirmed thoracic ESCC were retrospectively studied. These patients underwent radical esophagectomy with pathologic evaluation of lymph nodes. They al had 18F-FDG PET/CT scans in their preoperative staging procedures. None had a prior history of cancer. The pathologic status and PET/CT SUVmax of lymph nodes were col ected to calculate the receiver operating characteristic (ROC) curve and to determine the best cutoff value of the PET/CT SUVmax to distinguish benign from malignant lymph nodes. Lymph node data from 27 others were used for the validation. A total of 323 lymph nodes including 39 metastatic lymph nodes were evaluated in the training cohort, and 117 lymph nodes including 32 metastatic lymph nodes were evaluated in the validation cohort. The cutoff point of the SUVmax for lymph nodes was 4.1, as calculated by ROC curve (sensitivity, 80%; specificity, 92%;accuracy, 90%). When this cutoff value was applied to the validation cohort, a sensitivity, a specificity, and an accuracy of 81%, 88%, and 86%, respectively, were obtained. These results suggest that the SUVmax of lymph nodes predicts malignancy. Indeed, when an SUVmax of 4.1 was used instead of 2.5, FDG-PET/CT was more accurate in assessing nodal metastasis.

  19. Oxidative modification of high density lipoprotein induced by cultured human arterial smooth muscle cells

    江渝; 刘红; 彭家和; 叶治家; 何凤田; 董燕麟; 刘秉文


    Objective: To observe the oxidative modification of high density lipoprotein (HDL) induced by cultured human arterial smooth muscle cells (SMCs). Methods: HDL cocultured with SMCs at 37℃ in 48 h was subjected, and native HDL (N-HDL) served as control. Oxidative modification of HDL was identified by using agarose gel electrophoresis. Absorbances of conjugated diene (CD) and lipid hydroperoxide (LOOH) were measured with ultraviolet spectrophotometry at 234 and 560 nm respectively, and fluorescence intensity of thiobarbuturic acid reaction substance (TBARS) with fluorescence spectrophotometry at 550 nm emission wavelength with excitation at 515 nm. Results: In comparison with N-HDL, the electrophoretic mobility of SMCs-cocultured HDL was increased, and the contents of CD, LOOH and TBARS HDL were very significantly higher than those of the control HDL (P<0.01). Conclusion: Oxidative modification of HDL can be induced by human arterial SMCs.


    郭胤仕; 朱任之


    Objective To find out a specific method for diagnosis of malignant pleural effusions( MPEs )with higher sensitivity and practicality. Methods The diagnosis of MPEs were made using density gradient centrifugation ( DGC ) , smear cytologic examination (SCE) and pleural needle biopsy (PNB). Comparisons between these results and those of benign pleural effusions were also made. Results The positive rates of DGC,SCE and PNB for diagnosing MPEs were 94. 3% ,62.9% and 44.6% , respectively, and the positive rate of SCE combined with PNB for diagnosing MPEs was 73.2 %. The positive rate of the exfoliative tumor cells ( ETCs ) by DGC was much higher than that of SCE or/and PNB with no false-positive. Conclusion The ETCs isolated by DGC from the MPEs is quite specific for the diagnosis of malignant tumors with higher sensitivity and practicality in clinico-pathological practice.

  1. High density lipoprotein 3 inhibits oxidized low density lipoprotein-induced apoptosis via promoting cholesterol efflux in RAW264.7 cells

    Pei JIANG; Peng-ke YAN; Jian-xiong CHEN; Bing-yang ZHU; Xiao-yong LEI; Wei-dong YIN; Duan-fang LIAO


    Aim: To investigate the protective effect of high density lipoprotein 3 (HDL3) on oxidized low density lipoprotein (ox-LDL)-induced apoptosis in RAW264.7 cells.Methods: RAW264.7 cells were exposed to 50 mg/L ox-LDL for various durations up to 48 h, and apoptosis was detected using Hoechst 33258 staining and flow cytometric analysis. Total cholesterol levels were detected by high performance liquid chromatography, cholesterol efflux was determined by Tritium labeling, and the cellular lipid droplets were assayed by oil red O staining. Results: Treatment with 50 mg/L ox-LDL for 12, 24, and 48 h increased the apoptotic rate of RAW264.7 cells in a time-dependent manner. The peak apoptotic rate (47.7%) was observed after 48 h incubation. HDL3 at various concentrations (50 mg/L, 100 mg/L, and 200mg/L) inhibited the ox-LDL (50 mg/L for 48 h)-mediated apoptosis that was accompanied by an increased rate of intracellular cholesterol efflux, and decreased total cholesterol levels in cells in a concentration-dependent manner. Blockage of cholesterol efflux by brefeldin decreased the protective effect of HDL3 on ox-LDL-induced apoptosis. Increase of the cholesterol efflux effected by another cholesterol acceptor, β-cyclodextrin, led to a dramatic decrease in the apoptotic rate of cells. Conclusion: HDL3 antagonizes ox-LDL-induced apoptosis in RAW264.7cells, through reducing the accumulation of toxic cholesterol.

  2. Effects of oxidized low density lipoprotein on the growth of human artery smooth muscle cells

    ZHAO Gao-feng; SENG Jing-jing; ZHANG Hua; SHE Ming-peng


    Background Studies have shown that oxidized low density lipoprotein (ox-LDL) promotes the pathogenesis and development of atherosclerosis (AS), and that the proliferation, migration and phenotype alteration of vascular smooth muscle cells (vSMCs) into foam cells are critical changes in AS. It is proposed that ox-LDL might play a novel role in the pathologic process of vSMCs. The present study was performed ex vivo to investigate the effects of ox-LDL on the growth of cultured human vSMCs.Methods Using NaBr density gradient centrifugation, LDL from human plasma was isolated and purified. ox-LDL was produced from LDL after being incubated with CuSO4. ox-LDL was then added to the culture medium at different concentrations (25 μg/ml, 50 μg/ml, 75 μg/ml, 100 μg/ml, 125 μg/ml, and 150 μg/ml) for 7 days. The influence of ox-LDL on vSMC growth was observed from several aspects as growth curve, mitosis index, lipid staining, and in situ determination of apoptosis. The digital results were analyzed with SPSS 10.0.Results The ox-LDL produced ex vivo had a good purity and optimal oxidative degree, which was similar to the intrinsic ox-LDL in atherosclerotic plaque. ox-LDL at a concentration of 25 μg/ml demonstrated the strongest proliferation. At the concentration of 125 μg/ml, ox-LDL suppressed the growth of vSMCs. At concentrations of 25 μg/ml and 50 μg/ml, ox-LDL presented powerful mitotic trigger. When the concentration of ox-LDL increased, the mitotic index of vSMCs decreased gradually. ox-LDL induced more foam cells from vSMCs with rich intracellular lipid accumulation at concentrations of 25 μg/ml and 50 μg/ml. ox-LDL at higher concentrations induced more apoptotic vSMCs.Conclusions ox-LDL at lower concentrations may trigger proliferation and phenotype alteration into foam cells of vSMCs, and at higher concentrations it may induce apoptosis in vSMCs. ox-LDL plays an important role in the pathogenesis and development of atherosclerosis by its effect on v

  3. Leptin deficiency-induced obesity affects the density of mast cells in abdominal fat depots and lymph nodes in mice

    Altintas Mehmet M


    Full Text Available Abstract Background Mast cells are implicated in the pathogenesis of obesity and insulin resistance. Here, we explored the effects of leptin deficiency-induced obesity on the density of mast cells in metabolic (abdominal fat depots, skeletal muscle, and liver and lymphatic (abdominal lymph nodes, spleen, and thymus organs. Fourteen-week-old male leptin-deficient ob/ob mice and their controls fed a standard chow were studied. Tissue sections were stained with toluidine blue to determine the density of mast cells. CD117/c-kit protein expression analysis was also carried out. Furthermore, mast cells containing immunoreactive tumor necrosis factor-α (TNF-α, a proinflammatory cytokine involved in obesity-linked insulin resistance, were identified by immunostaining. Results ob/ob mice demonstrated adiposity and insulin resistance. In abdominal fat depots, mast cells were distributed differentially. While most prevalent in subcutaneous fat in controls, mast cells were most abundant in epididymal fat in ob/ob mice. Leptin deficiency-induced obesity was accompanied by a 20-fold increase in the density of mast cells in epididymal fat, but a 13-fold decrease in subcutaneous fat. This finding was confirmed by CD117/c-kit protein expression analysis. Furthermore, we found that a subset of mast cells in epididymal and subcutaneous fat were immunoreactive for TNF-α. The proportion of mast cells immunoreactive for TNF-α was higher in epididymal than in subcutaneous fat in both ob/ob and control mice. Mast cells were also distributed differentially in retroperitoneal, mesenteric, and inguinal lymph nodes. In both ob/ob mice and lean controls, mast cells were more prevalent in retroperitoneal than in mesenteric and inguinal lymph nodes. Leptin deficiency-induced obesity was accompanied by increased mast cell density in all lymph node stations examined. No significant difference in the density of mast cells in skeletal muscle, liver, spleen, and thymus was

  4. Oxidized low-density lipoprotein and β-glycerophosphate synergistically induce endothelial progenitor cell ossification

    Li LIU; Zhi-zhong LIU; Hui CHEN; Guo-jun ZHANG; Yu-hua KONG; Xi-xiong KANG


    To investigate the ability of ox-LDL to induce ossification of endothelial progenitor cells (EPCs) in vitro and explored whether oxidative stress,especially hypoxia inducible factor-1α (HIF-1α) and reactive oxygen species (ROS),participate in the ossific process.Methods:Rat bone marrow-derived endothelial progenitor cells (BMEPCs) were cultured in endothelial growth medium supplemented with VEGF (40 ng/mL) and bFGF (10 ng/mL).The cells were treated with oxidized low-density lipoprotein (ox-LDL,5 μg/mL) and/or β-glycerophosphate (β-GP,10 mmol/L).Calcium content and Von Kossa staining were used as the measures of calcium deposition.Ossific gene expression was determined using RT-PCR.The expression of osteocalcin (OCN) was detected with immunofluorescence.Alkaline phosphatase (ALP) activity was analyzed using colorimetric assay.Intercellular reactive oxygen species (ROS) were measured with flow cytometry.Results:BMEPCs exhibited a spindle-like shape.The percentage of cells that expressed the cell markers of EPCs CD34,CD133,and kinase insert domain-containing receptor (KDR) were 46.2%+5.8%,23.5%+4.0%,and 74.3%+8.8%,respectively.Among the total cells,78.3%+4.2% were stained with endothelial-specific fluorescence.Treatment of BMEPCs with ox-LDL significantly promoted calcium deposition,which was further significantly enhanced by co-treatment with β-GP.The same treatments significantly increased the gene expression of core-binding factor a-1 (cbfa-1) and OCN,while decreased the gene expression of osteoprotegerin (OPG).The treatments also significantly enhanced the activity of ALP,but did not affect the number of OCN+ cells.Furthermore,the treatments significantly increased ROS and activated the hypoxia inducible factor-1α (HIF-1α).In all these effects,ox-LDL acted synergistically with β-GP.Conclusion:Ox-LDL and β-GP synergistically induce ossification of BMEPCs,in which an oxidizing mechanism is involved.

  5. High-Density and Very-Low-Density Lipoprotein Have Opposing Roles in Regulating Tumor-Initiating Cells and Sensitivity to Radiation in Inflammatory Breast Cancer

    Wolfe, Adam R. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Atkinson, Rachel L. [Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Reddy, Jay P. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Debeb, Bisrat G.; Larson, Richard; Li, Li [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Department of Clinical Cancer Prevention, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Masuda, Hiroko; Brewer, Takae [Department of Clinical Cancer Prevention, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Atkinson, Bradley J. [Department of Clinical Pharmacy Services, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Brewster, Abeena [Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Ueno, Naoto T. [Department of Clinical Cancer Prevention, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Woodward, Wendy A., E-mail: [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Department of Clinical Cancer Prevention, University of Texas MD Anderson Cancer Center, Houston, Texas (United States)


    Purpose: We previously demonstrated that cholesterol-lowering agents regulate radiation sensitivity of inflammatory breast cancer (IBC) cell lines in vitro and are associated with less radiation resistance among IBC patients who undergo postmastectomy radiation. We hypothesized that decreasing IBC cellular cholesterol induced by treatment with lipoproteins would increase radiation sensitivity. Here, we examined the impact of specific transporters of cholesterol (ie lipoproteins) on the responses of IBC cells to self-renewal and to radiation in vitro and on clinical outcomes in IBC patients. Methods and Materials: Two patient-derived IBC cell lines, SUM 149 and KPL4, were incubated with low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), or high-density lipoproteins (HDL) for 24 hours prior to irradiation (0-6 Gy) and mammosphere formation assay. Cholesterol panels were examined in a cohort of patients with primary IBC diagnosed between 1995 and 2011 at MD Anderson Cancer Center. Lipoprotein levels were then correlated to patient outcome, using the log rank statistical model, and examined in multivariate analysis using Cox regression. Results: VLDL increased and HDL decreased mammosphere formation compared to untreated SUM 149 and KPL4 cells. Survival curves showed enhancement of survival in both of the IBC cell lines when pretreated with VLDL and, conversely, radiation sensitization in all cell lines when pretreated with HDL. In IBC patients, higher VLDL values (>30 mg/dL) predicted a lower 5-year overall survival rate than normal values (hazard ratio [HR] = 1.9 [95% confidence interval [CI]: 1.05-3.45], P=.035). Lower-than-normal patient HDL values (<60 mg/dL) predicted a lower 5-year overall survival rate than values higher than 60 mg/dL (HR = 3.21 [95% CI: 1.25-8.27], P=.015). Conclusions: This study discovered a relationship among the plasma levels of lipoproteins, overall patient response, and radiation resistance in IBC patients

  6. Exosome mediated growth effect on the non-growing pre-B acute lymphoblastic leukemia cells at low starting cell density

    Patel, Sapan J; Darie, Costel C; Clarkson, Bayard D


    Tumors contain heterogeneous cell populations and achieve dominance by functioning as collective systems. The mechanisms underlying the aberrant growth and interactions between cells are not very well understood. The pre-B acute lymphoblastic leukemia cells we studied were obtained directly from a patient with Ph+ ALL. A new Ph+ ALL cell line (ALL3) was established from the leukemic cells growing as ascitic cells in his pleural fluid. The patient died of his disease shortly after the cells were obtained. ALL3 cells grow well at high cell densities (HD), but not at low cell densities. ALL3 cells are very sensitive to potent tyrosine kinase inhibitors (TKIs) such as Dasatinib and PD166325, but less sensitive to AMN 107, Imatinib, and BMS 214662 (a farnesyl transferase inhibitor). Here, we show that the growth of the LD ALL3 cells can be stimulated to grow in the presence of diffusible, soluble factors secreted by ALL3 cells themselves growing at high density. We also show that exosomes, part of the secretome components, are also able to stimulate the growth of the non-growing LD ALL3 cells and modulate their proliferative behavior. Characterization of the exosome particles also showed that the HD ALL3 cells are able to secret them in large quantities and that they are capable of inducing the growth of the LD ALL3 cells without which they will not survive. Direct stimulation of non-growing LD ALL3 cells using purified exosomes shows that the ALL3 cells can also communicate with each other by means of exchange of exosomes independently of direct cell-cell contacts or diffusible soluble stimulatory factors secreted by HD ALL3 cells. PMID:27725845

  7. Involvement of mast cells and microvessels density in reactive lesions of oral cavity: A comparative immunohistochemical study.

    Ferreira, Stephany Vasco; Xavier, Flávia Caló Aquino; Freitas, Maria da Conceição Andrade de; Nunes, Fábio Daumas; Gurgel, Clarissa Araújo; Cangussu, Maria Cristina Teixeira; Martins, Manoela Domingues; Freitas, Valéria Souza; Dos Santos, Jean Nunes


    In view of the similarity of clinicopathological features between reactive lesions of the oral cavity, the objective of the present study was to investigate the density of MCs (mast cells) and microvessels in a series of these lesions. Thirty-seven cases of reactive lesions including fibrous hyperplasia (FH, n=10), inflammatory fibrous hyperplasia (IFH, n=10), peripheral giant cell lesion (PGCL, n=10) and lobular capillary hemangioma (LCH, n=7) were investigated using immunohistochemistry for mast cell tryptase and CD34. For comparative purposes, central giant cell lesions (CGCL, n=5) were included. A higher MC density was observed in LCH (37.01), while CGCL exhibited the lowest density (n=8.14). There was a significant difference in MC density when all reactive lesions were compared to CGCL (p=0.001). The largest mean density of microvessels was observed in LCH (n=21.69). The smallest number was observed in CGCL (n=6.24). There was a significant difference in microvessel density when the reactive lesions were compared to CGCL (p=0.003). There was a significant and direct correlation between the density of MCs and microvessels only for IFH (p=0.048) and CGCL (p=0.005). A significant and direct correlation between the mean density of MCs and microvessels was observed when the reactive lesions were analyzed as a whole (p=0.005). Our results suggest that mast cells contribute to the connective tissue framework and angiogenic function, as well as the development, of reactive lesions of the oral cavity, including FH, IFH, LCH and PGCL.

  8. Increased COX-2 expression in epithelial and stromal cells of high mammographic density tissues and in a xenograft model of mammographic density.

    Chew, G L; Huo, C W; Huang, D; Hill, P; Cawson, J; Frazer, H; Hopper, J L; Haviv, I; Henderson, M A; Britt, K; Thompson, E W


    Mammographic density (MD) adjusted for age and body mass index is one of the strongest known risk factors for breast cancer. Given the high attributable risk of MD for breast cancer, chemoprevention with a safe and available agent that reduces MD and breast cancer risk would be beneficial. Cox-2 has been implicated in MD-related breast cancer risk, and was increased in stromal cells in high MD tissues in one study. Our study assessed differential Cox-2 expression in epithelial and stromal cells in paired samples of high and low MD human breast tissue, and in a validated xenograft biochamber model of MD. We also examined the effects of endocrine treatment upon Cox-2 expression in high and low MD tissues in the MD xenograft model. Paired high and low MD human breast tissue samples were immunostained for Cox-2, then assessed for differential expression and staining intensity in epithelial and stromal cells. High and low MD human breast tissues were separately maintained in biochambers in mice treated with Tamoxifen, oestrogen or placebo implants, then assessed for percentage Cox-2 staining in epithelial and stromal cells. Percentage Cox-2 staining was greater for both epithelial (p = 0.01) and stromal cells (p tissues. In high MD biochamber tissues, percentage Cox-2 staining was greater in stromal cells of oestrogen-treated versus placebo-treated tissues (p = 0.05).

  9. Interdependence of initial cell density, drug concentration and exposure time revealed by real-time impedance spectroscopic cytotoxicity assay

    Caviglia, Claudia; Zor, Kinga; Canepa, Silvia


    We investigated the combined effect of the initial cell density (12 500, 35 000, 75 000, and 100 000 cells cm−2) and concentration of the anti-cancer drug doxorubicin on HeLa cells by performing timedependent cytotoxicity assays using real-time electrochemical impedance spectroscopy. A correlation...... between the rate of cell death and the initial cell seeding density was found at 2.5 μM doxorubicin concentration, whereas this was not observed at 5 or 100 μM. By sensing the changes in the cell–substrate interaction using impedance spectroscopy under static conditions, the onset of cytotoxicity...... was observed 5 h earlier than when using a standard colorimetric end-point assay (MTS) which measures changes in the mitochondrial metabolism. Furthermore, with the MTS assay no cytotoxicity was observed after 15 h of incubation with 2.5 μM doxorubicin, whereas the impedance showed at this time point cell...

  10. Changes in small intestinal chromogranin A-immunoreactive cell densities in patients with irritable bowel syndrome after receiving dietary guidance.

    Mazzawi, Tarek; El-Salhy, Magdy


    Chromogranin A (CgA) is a common marker for enteroendocrine cells in the gut, and CgA-immunoreactive cell densities are abnormal in patients with irritable bowel syndrome (IBS). The majority of patients with IBS report that their symptoms develop after consuming certain foodstuffs. In the present study, we investigated the effects of dietary guidance on the total enteroendocrine cell densities in the small intestine, as detected by CgA. A total of 14 patients with IBS underwent a gastroscopy with duodenal biopsies and 11 of them also underwent a colonoscopy, with biopsy samples obtained from the ileum. Fourteen control subjects were also included. Each patient received 3 sessions of dietary guidance. Gastroscopies and colonoscopies were performed on both the controls and patients with IBS (at baseline and at 3-9 months after receiving guidance). Biopsy samples obtained from the duodenum and ileum were immunostained for CgA using the avidin-biotin complex (ABC) method and were quantified using computerized image analysis. The density of CgA-immunoreactive cells in the duodenum (mean ± SEM values) in the control subjects was 235.9 ± 31.9 cells/mm2; in the patients with IBS, the density was 36.9 ± 9.8 and 103.7 ± 16.9 cells/mm2 before and after they received dietary guidance, respectively (P=0.007). The density of CgA-immunoreactive cells in the ileum in the control subjects was 47.4 ± 8.3 cells/mm2; in the patients with IBS, the density was 48.4 ± 8.1 and 17.9 ± 4.4 cells/mm2, before and after they received dietary guidance, respectively (P=0.0006). These data indicate that changes in CgA-immunoreactive cell densities in patients with IBS after receiving dietary guidance may reflect a change in the densities of the small intestinal enteroendocrine cells, which may contribute to an improvement in the IBS symptoms.

  11. Colominic acid inhibits the proliferation of cultured bovine aortic endothelial cells and injures their monolayers: cell density-dependent effects prevented by sulfation.

    Yamamoto, Chika; Morita, Yuki; Yamaguchi, Shinya; Hayashi, Toshimitsu; Kaji, Toshiyuki


    Colominic acid (CA), produced by Escherichia coli K1, is a polymer of sialic acid linked through alpha (2-->8) glycosidic linkages. Although there are several studies on the biological activities of chemically sulfated CA, the activity of CA has been incompletely understood. In the present study, we investigated the effects of CA, prepared as an alpha2,8-linked homopolymer of N-acetylneuraminic acid, on the proliferation and monolayer maintenance of bovine aortic endothelial cells in culture. The results indicate that CA potently inhibits the proliferation of sparse endothelial cells without nonspecific cell damage. The inhibitory effect of CA was markedly stronger than those of sodium spirulan and calcium spirulan, known polysaccharides that inhibit endothelial cell proliferation. On the other hand, in dense endothelial cells, CA induced nonspecific cell damage and markedly injured the monolayer. These results indicate that CA has two distinct effects on vascular endothelial cells: one is the inhibition of proliferation when the cell density is low, and the other is the nonspecific cytotoxicity when the cell density is high. Interestingly, these cell density-dependent effects of CA could be prevented by sulfation of the CA chains. Therefore, it is concluded that CA not only inhibits the proliferation of sparse endothelial cells without nonspecific cell damage but also injures dense cells in a monolayer by nonspecific cytotoxicity, which can be prevented by sulfation of the polysaccharide.

  12. High and low density PHA- (but not ConA-) activated T cells stimulate the autologous mixed lymphocyte reaction.

    Brahmi, Z; Thomas, J E


    In this study, PHA- and ConA-activated cells (PAC and CAC) were used as stimulators in mixed lymphocyte reactions (MLR) using autologous (auto) and allogeneic (allo) peripheral mononuclear cells as responders. PAC, but not CAC, were stimulatory in allo- and auto-MLR, and this stimulation was not due to residual PHA. In PAC which have been activated for 96 h, auto-MLR was due to determinants present on low density T-cell blasts, while with PAC which had been stimulated for more than 192 h, the determinants seemed to be associated with high density T cells. Anti-T3 monoclonal antibodies and certain anti-DR suppressed auto- and allo-MLR mediated by PAC when present throughout the entire MLR assays. CAC suppressed PAC-mediated auto-MLR in a dose-dependent fashion. This inhibition was not DR-restricted and was reversed by the addition of exogenous IL-2. Our results indicate that: depending upon the length of activation, both low density and high density PHA-activated T cells exhibited strong stimulatory capacity in auto-MLR; ConA-activated T cells failed to stimulate auto- or allo-MLR and suppressed MLR mediated by PAC; this suppression was due to suppressor cells, not to suppressor factors, and was readily reversed by exogenous IL-2; pretreatment of CAC with anti-TAC did not reverse the inhibition.

  13. Maximum likely scale estimation

    Loog, Marco; Pedersen, Kim Steenstrup; Markussen, Bo


    A maximum likelihood local scale estimation principle is presented. An actual implementation of the estimation principle uses second order moments of multiple measurements at a fixed location in the image. These measurements consist of Gaussian derivatives possibly taken at several scales and/or ...

  14. Spatially resolved determination of the short-circuit current density of silicon solar cells via lock-in thermography

    Fertig, Fabian, E-mail:; Greulich, Johannes; Rein, Stefan [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstr. 2, D-79110 Freiburg (Germany)


    We present a spatially resolved method to determine the short-circuit current density of crystalline silicon solar cells by means of lock-in thermography. The method utilizes the property of crystalline silicon solar cells that the short-circuit current does not differ significantly from the illuminated current under moderate reverse bias. Since lock-in thermography images locally dissipated power density, this information is exploited to extract values of spatially resolved current density under short-circuit conditions. In order to obtain an accurate result, one or two illuminated lock-in thermography images and one dark lock-in thermography image need to be recorded. The method can be simplified in a way that only one image is required to generate a meaningful short-circuit current density map. The proposed method is theoretically motivated, and experimentally validated for monochromatic illumination in comparison to the reference method of light-beam induced current.

  15. The effect of oxidized low-density lipoprotein combined with adriamycin on the proliferation of Eca-109 cell line


    Abstract Background The purpose of this study was to identify the affect on the proliferation Eca-109 cells treated with oxidized low-density lipoprotein (ox-LDL) combined with adriamycin (ADM). Methods Eca-109 cell were cultured in the presence of oxLDL/ADM, and cell proliferation tested by MTT and cell apoptosis was monitored by the proportion of apoptosis and cell cycle by flow cytomester. We simultaneously evaluated the level of associated- apoptosis Bcl-2, Bax, and Caspase-3 gene mRNA an...

  16. Optimized LTE Cell Planning with Varying Spatial and Temporal User Densities

    Ghazzai, Hakim


    Base station deployment in cellular networks is one of the fundamental problems in network design. This paper proposes a novel method for the cell planning problem for the fourth generation (4G) cellular networks using meta-heuristic algorithms. In this approach, we aim to satisfy both cell coverage and capacity constraints simultaneously by formulating an optimization problem that captures practical planning aspects. The starting point of the planning process is defined through a dimensioning exercise that captures both coverage and capacity constraints. Afterwards, we implement a meta-heuristic algorithm based on swarm intelligence (e.g., particle swarm optimization or the recently-proposed grey wolf optimizer) to find suboptimal base station locations that satisfy both problem constraints in the area of interest which can be divided into several subareas with different spatial user densities. Subsequently, an iterative approach is executed to eliminate eventual redundant base stations. We also perform Monte Carlo simulations to study the performance of the proposed scheme and compute the average number of users in outage. Next, the problems of green planning with regards to temporal traffic variation and planning with location constraints due to tight limits on electromagnetic radiations are addressed, using the proposed method. Finally, in our simulation results, we apply our proposed approach for different scenarios with different subareas and user distributions and show that the desired network quality of service targets are always reached even for large-scale problems.

  17. Edaravone attenuates monocyte adhesion to endothelial cells induced by oxidized low-density lipoprotein

    Li, Zhijuan, E-mail:; Cheng, Jianxin; Wang, Liping


    Oxidized low-density lipoprotein (oxLDL) plays a vital role in recruitment of monocytes to endothelial cells, which is important during early stages of atherosclerosis development. Edaravone, a potent and novel scavenger of free radicals inhibiting hydroxyl radicals, has been clinically used to reduce the neuronal damage following ischemic stroke. In the present study, Edaravone was revealed to markedly reduce oxLDL-induced monocyte adhesion to human umbilical vein endothelial cells (HUVECs). The inhibitory mechanism of Edaravone was associated with suppression of the chemokine MCP-1 and adhesion molecule VCAM-1 and ICAM-1 expression. In addition, luciferase reporter assay results revealed that administration of Edaravone attenuated the increase in NF-κB transcriptional activity induced by oxLDL. Notably, it's also shown that Edaravone treatment blocked oxLDL induced p65 nuclear translocation in HUVECs. Results indicate that Edaravone negatively regulates endothelial inflammation. - Highlights: • Edaravone reduces oxLDL-induced monocyte adhesion to HUVECs. • Edaravone attenuates oxLDL-induced expression of MCP-1, VCAM-1, and ICAM-1. • Edaravone reduces NF-κB transcriptional activity and p65 nuclear translocation.

  18. Optimized LTE cell planning for multiple user density subareas using meta-heuristic algorithms

    Ghazzai, Hakim


    Base station deployment in cellular networks is one of the most fundamental problems in network design. This paper proposes a novel method for the cell planning problem for the fourth generation 4G-LTE cellular networks using meta heuristic algorithms. In this approach, we aim to satisfy both coverage and cell capacity constraints simultaneously by formulating a practical optimization problem. We start by performing a typical coverage and capacity dimensioning to identify the initial required number of base stations. Afterwards, we implement a Particle Swarm Optimization algorithm or a recently-proposed Grey Wolf Optimizer to find the optimal base station locations that satisfy both problem constraints in the area of interest which can be divided into several subareas with different user densities. Subsequently, an iterative approach is executed to eliminate eventual redundant base stations. We have also performed Monte Carlo simulations to study the performance of the proposed scheme and computed the average number of users in outage. Results show that our proposed approach respects in all cases the desired network quality of services even for large-scale dimension problems.

  19. Paralytic shellfish toxin concentration and cell density changes in Pyrodinium bahamense -Noctiluca scintillans feeding experiments.

    Azanza, Rhodora V; Cruz, Lourdes J; Cariño, Flerida A; Blanco, Alelea G; Butardo, Vito M


    For the first time the potential of Noctiluca scintillans, a non-toxic mixotrophic dinoflagellate, in bioconverting and/or excreting saxitoxin has been illustrated, thus contributing to the limited knowledge on the aspects of toxin pathways in the food chain/web and predator-prey preferences. Noctiluca growth rate increased with higher Pyrodinium concentration but the ratio of Noctiluca to Pyrodinium should at least be 1:250 cells per mL. Noctiluca fed with Pyrodinium alone was found to decrease in number suggesting that the nutrients from this prey were insufficient. This was confirmed by the improved cell density of Noctiluca upon addition of 0.01% casitone to the Pyrodinium-fed Noctiluca. The alternative prey (Gymnodinium sanguineum) slowed down the grazing impact of Noctiluca on Pyrodinium. Noctiluca depleted Gymnodinium earlier than Pyrodinium showing preference over a prey with less saxitoxin. After the feeding experiments, total saxitoxin levels decreased to 72% in the Noctiluca-Pyrodinium setup whereas no saxitoxin was detected in the Noctiluca culture fed with Pyrodinium and G. sanguineum. It is possible that Gymnodinium can provide some nutrients needed to make Noctiluca more efficient in bioconverting saxitoxin.

  20. High cell-density production of poly(3-hydroxybutyrate) in a membrane bioreactor.

    Haas, Cornelia; El-Najjar, Tarek; Virgolini, Nikolaus; Smerilli, Marina; Neureiter, Markus


    Agro-industrial residues with a low carbon content, such as whey, stillage or wastewater from plant oil mills are abundant and cheap. However, they cannot be used directly in highly productive industrial poly(3-hydroxybutyrate) (P3HB) production, as the classical fed-batch fermentation strategy requires highly concentrated feed streams. This problem has been circumvented in this report by retaining the cells during the fermentation in the bioreactor using an external microfiltration module. Synthetic medium containing a glucose concentration of 50g/L was continuously fed to Cupriavidus necator, which converted the sugar to P3HB. With this setup we were able to achieve high productivities (3.10g P3HB/(Lh)) and reach high cell densities (148g/L) containing 76% P3HB, and obtained good yields (0.33g P3HB/g added glucose). The added sugar from the feed was instantly consumed by the bacteria, resulting in a negligible loss of sugar to the permeate. This approach creates the possibility of polyhydroxyalkanoate production from a range of cheap and easily available substrates, for which only waste water treatment or biogas production has been cost-competitive until now.

  1. High-Density Lipoprotein-Mediated Transcellular Cholesterol Transport in Mouse Aortic Endothelial Cells

    Miao, LiXia; Okoro, Emmanuel U.; Cao, ZhiJan; Yang, Hong; Motley-Johnson, Evangeline; Guo, Zhongmao


    Accumulation of unesterified cholesterol-rich lipid vesicles in the subendothelial space contributes to atherogenesis. Transport of cholesterol from the subendothelial intima back to the circulating blood inhibits atherosclerosis development; however, the mechanism for this process has not been fully defined. Using cultured mouse aortic endothelial cells (MAECs), we observed that unesterified cholesterol can be transported across the endothelial cell monolayer from the basolateral to the apical compartment. Administration of high-density lipoprotein (HDL) or apolipoprotein AI (apoAI) to the apical compartment enhanced transendothelial cholesterol transport in a concentration-dependent manner. Knockdown of ATP-binding cassette transporter G1 (ABCG1) or scavenger receptor class B type I (SR-B1), or inhibition of SR-B1 diminished HDL-induced transendothelial cholesterol transport; while knockdown of ABCA1 reduced apoAI-mediated cholesterol transport. HDL enhanced phosphorylation of phosphatidylinositol 3-kinase (PI3K) and Akt in MAECs. However, inhibition PI3K or Akt did not reduce HDL-induced transendothelial cholesterol transport. These results suggest that HDL enhances transendothelial cholesterol transport by activation of a mechanism involving ABCA1, ABCA1 and SR-B1 but not involving PI3K and Akt. PMID:26255968

  2. Enhancement of lipid productivity of Rhodosporidium toruloides in distillery wastewater by increasing cell density.

    Ling, Jiayin; Nip, Saiwa; Shim, Hojae


    This study is to improve the process of producing lipid convertible to biodiesel, from distillery wastewater while simultaneously removing organics and nutrients efficiently by inoculating oleaginous yeast Rhodosporidium toruloides in the presence of indigenous microorganisms. The lipid productivity of R. toruloides was studied using real wastewater obtained from distillery and local municipal wastewater treatment plants. Under the conditions of mix rate of 1:1 with domestic wastewater, initial soluble chemical oxygen demand (SCOD) over 20,000 mg/L and initial cell density of 2×10(7) cells/mL at 30 °C, lipid content and lipid yield achieved were 43.65±1.74% and 3.54±0.04 g/L, with the associated removal efficiencies for COD, total nitrogen (TN), and total phosphorus (TP), 86.11±0.41%, 57.81±0.29%, and 67.69±0.73%, respectively, after three days of cultivation in real distillery wastewater without pH adjustment. The pH of wastewater increased from 3.71 to over 8 in 7 days of cultivation.

  3. Increased extracellular matrix density decreases MCF10A breast cell acinus formation in 3D culture conditions.

    Lance, Amanda; Yang, Chih-Chao; Swamydas, Muthulekha; Dean, Delphine; Deitch, Sandy; Burg, Karen J L; Dréau, Didier


    The extracellular matrix (ECM) contributes to the generation and dynamic of normal breast tissue, in particular to the generation of polarized acinar and ductal structures. In vitro 3D culture conditions, including variations in the composition of the ECM, have been shown to directly influence the formation and organization of acinus-like and duct-like structures. Furthermore, the density of the ECM appears to also play a role in the normal mammary tissue and tumour formation. Here we show that the density of the ECM directly influences the number, organization and function of breast acini. Briefly, non-malignant human breast MCF10A cells were incubated in increasing densities of a Matrigel®-collagen I matrix. Elastic moduli near and distant to the acinus structures were measured by atomic force microscopy, and the number of acinus structures was determined. Immunochemistry was used to investigate the expression levels of E-cadherin, laminin, matrix metalloproteinase-14 and ß-casein in MCF10A cells. The modulus of the ECM was significantly increased near the acinus structures and the number of acinus structures decreased with the increase in Matrigel-collagen I density. As evaluated by the expression of laminin, the organization of the acinus structures present was altered as the density of the ECM increased. Increases in both E-cadherin and MMP14 expression by MCF10A cells as ECM density increased were also observed. In contrast, MCF10A cells expressed lower ß-casein levels as the ECM density increased. Taken together, these observations highlight the key role of ECM density in modulating the number, organization and function of breast acini.

  4. Nicotine-induced expression of low-density lipoprotein receptor in oral epithelial cells.

    Ito, Satoshi; Gojoubori, Takahiro; Tsunoda, Kou; Yamaguchi, Yoko; Asano, Masatake; Goke, Eiji; Koshi, Ryosuke; Sugano, Naoyuki; Yoshinuma, Naoto; Komiyama, Kazuo; Ito, Koichi


    Nicotine use is one of the most important risk factors for the development of cardiovascular and periodontal diseases. Numerous reports have suggested the possible contribution of disturbed lipid metabolism for the development of both disease groups. Despite these observations, little is known about the relationship between tobacco smoking and the development of these diseases. Our previous microarray data revealed that nicotine induced low-density lipoprotein receptor (LDLR) expression in oral epithelial cells (OECs). The aim of the present study was to confirm nicotine-mediated LDLR induction and to elucidate the signaling mechanisms leading to the augmented expression of LDLR in OECs. LDLR and nicotinic acetylcholine receptor (nAChR) subunit expression was detected by real-time PCR. The production of LDLR was demonstrated by immunofluorescence staining. nAChR-mediated LDLR induction was examined by pre-incubation of the cells with its specific inhibitor, α-bungarotoxin (α-BTX). The functional importance of transcription factor specific protein 1 (Sp1) was examined by luciferase assay, mithramycin pre-incubation or by small interfering RNA (siRNA) transfection. The specific binding of Sp1 to R3 region of LDLR 5'-untranslated region was demonstrated with electrophoretic mobility shift assay (EMSA) and streptavidin-agarose precipitation assay followed by western blotting. The results confirmed that nicotine induced LDLR expression at the transcriptional level. Nicotine was sensed by nAChR and the signal was transduced by Sp1 which bound to the R3 region of LDLR gene. Augmented production of LDLR in the gingival epithelial cells was further demonstrated by immunofluorescence staining using the gingival tissues obtained from the smoking patients. Taken together, the results suggested that nicotine might contribute to the development of both cardiovascular and periodontal diseases by inducing the LDLR in OECs thereby disturbing lipid metabolism.

  5. Nicotine-induced expression of low-density lipoprotein receptor in oral epithelial cells.

    Satoshi Ito

    Full Text Available BACKGROUND: Nicotine use is one of the most important risk factors for the development of cardiovascular and periodontal diseases. Numerous reports have suggested the possible contribution of disturbed lipid metabolism for the development of both disease groups. Despite these observations, little is known about the relationship between tobacco smoking and the development of these diseases. Our previous microarray data revealed that nicotine induced low-density lipoprotein receptor (LDLR expression in oral epithelial cells (OECs. The aim of the present study was to confirm nicotine-mediated LDLR induction and to elucidate the signaling mechanisms leading to the augmented expression of LDLR in OECs. METHODS AND RESULTS: LDLR and nicotinic acetylcholine receptor (nAChR subunit expression was detected by real-time PCR. The production of LDLR was demonstrated by immunofluorescence staining. nAChR-mediated LDLR induction was examined by pre-incubation of the cells with its specific inhibitor, α-bungarotoxin (α-BTX. The functional importance of transcription factor specific protein 1 (Sp1 was examined by luciferase assay, mithramycin pre-incubation or by small interfering RNA (siRNA transfection. The specific binding of Sp1 to R3 region of LDLR 5'-untranslated region was demonstrated with electrophoretic mobility shift assay (EMSA and streptavidin-agarose precipitation assay followed by western blotting. The results confirmed that nicotine induced LDLR expression at the transcriptional level. Nicotine was sensed by nAChR and the signal was transduced by Sp1 which bound to the R3 region of LDLR gene. Augmented production of LDLR in the gingival epithelial cells was further demonstrated by immunofluorescence staining using the gingival tissues obtained from the smoking patients. CONCLUSIONS: Taken together, the results suggested that nicotine might contribute to the development of both cardiovascular and periodontal diseases by inducing the LDLR in

  6. Electrical protein detection in cell lysates using high-density peptide-aptamer microarrays

    Evans David


    Full Text Available Abstract Background The dissection of biological pathways and of the molecular basis of disease requires devices to analyze simultaneously a staggering number of protein isoforms in a given cell under given conditions. Such devices face significant challenges, including the identification of probe molecules specific for each protein isoform, protein immobilization techniques with micrometer or submicrometer resolution, and the development of a sensing mechanism capable of very high-density, highly multiplexed detection. Results We present a novel strategy that offers practical solutions to these challenges, featuring peptide aptamers as artificial protein detectors arrayed on gold electrodes with feature sizes one order of magnitude smaller than existing formats. We describe a method to immobilize specific peptide aptamers on individual electrodes at the micrometer scale, together with a robust and label-free electronic sensing system. As a proving proof of principle experiment, we demonstrate the specific recognition of cyclin-dependent protein kinases in whole-cell lysates using arrays of ten electrodes functionalized with individual peptide aptamers, with no measurable cross-talk between electrodes. The sensitivity is within the clinically relevant range and can detect proteins against the high, whole-cell lysate background. Conclusion The use of peptide aptamers selected in vivo to recognize specific protein isoforms, the ability to functionalize each microelectrode individually, the electronic nature and scalability of the label-free detection and the scalability of the array fabrication combine to yield the potential for highly multiplexed devices with increasingly small detection areas and higher sensitivities that may ultimately allow the simultaneous monitoring of tens or hundreds of thousands of protein isoforms.

  7. High cell density propionic acid fermentation with an acid tolerant strain of Propionibacterium acidipropionici.

    Wang, Zhongqiang; Jin, Ying; Yang, Shang-Tian


    Propionic acid is an important chemical with wide applications and its production via fermentation is of great interest. However, economic production of bio-based propionic acid requires high product titer, yield, and productivity in the fermentation. A highly efficient and stable high cell density (HCD) fermentation process with cell recycle by centrifugation was developed for propionic acid production from glucose using an acid-tolerant strain of Propionibacterium acidipropionici, which had a higher specific growth rate, productivity, and acid tolerance compared to the wild type ATCC 4875. The sequential batch HCD fermentation at pH 6.5 produced propionic acid at a high titer of ∼40 g/L and productivity of 2.98 g/L h, with a yield of ∼0.44 g/g. The product yield increased to 0.53-0.62 g/g at a lower pH of 5.0-5.5, which, however, decreased the productivity to 1.28 g/L h. A higher final propionic acid titer of >55 g/L with a productivity of 2.23 g/L h was obtained in fed-batch HCD fermentation at pH 6.5. A 3-stage simulated fed-batch process in serum bottles produced 49.2 g/L propionic acid with a yield of 0.53 g/g and productivity of 0.66 g/L h. These productivities, yields and propionic acid titers were among the highest ever obtained in free-cell propionic acid fermentation.

  8. Laparoscopic real-time en-face differential optical topography of near-surface heterogeneity by using an applicator probe with the maximum-density radially alternating illumination and detection fiber-channels

    Piao, Daqing; Holyoak, G Reed; Patel, Sanjay


    We demonstrate a laparoscopic applicator probe and a method thereof for real-time en-face topographic mapping of near-surface heterogeneity for potential use in intraoperative margin assessment during minimally invasive oncological procedures. The probe fits in a 12mm port and houses at its maximum 128 copper-coated 750um fibers that form radially alternating illumination (70 fibers) and detection (58 fibers) channels. By simultaneously illuminating the 70 source channels of the probe that is in contact with a scattering medium and concurrently measuring the light diffusely propagated to the 58 detector channels, the presence of near-surface optical heterogeneities can be resolved in an en-face 9.5mm field-of-view in real-time. Visualization of a subsurface margin of strong attenuation contrast at a depth up to 3mm is demonstrated at one wavelength at a frame rate of 1.25Hz.

  9. The large-scale correlations of multi-cell densities and profiles, implications for cosmic variance estimates

    Codis, Sandrine; Pichon, Christophe


    In order to quantify the error budget in the measured probability distribution functions of cell densities, the two-point statistics of cosmic densities in concentric spheres is investigated. Bias functions are introduced as the ratio of their two-point correlation function to the two-point correlation of the underlying dark matter distribution. They describe how cell densities are spatially correlated. They are computed here via the so-called large deviation principle in the quasi-linear regime. Their large-separation limit is presented and successfully compared to simulations for density and density slopes: this regime is shown to be rapidly reached allowing to get sub-percent precision for a wide range of densities and variances. The corresponding asymptotic limit provides an estimate of the cosmic variance of standard concentric cell statistics applied to finite surveys. More generally, no assumption on the separation is required for some specific moments of the two-point statistics, for instance when pre...

  10. Size- and density-dependent elution of normal and pathological red blood cells by gravitational field-flow fractionation.

    Cardot, P J; Elgéa, C; Guernet, M; Godet, D; Andreux, J P


    Elution of normal and pathological human red blood cells (RBCs) was performed by gravitational field-flow fractionation (GFFF). The reproducibility of the retention factor was lower than 10% and elution at high and low flow-rates confirmed the existence of "lifting forces". No direct correlation between size and retention was observed for normal RBCs in the absence of density information. Elution of pathological human RBCs, known to be modified in shape, density and rigidity, was performed. The elution parameters confirmed that the retention mechanism of RBCs is at least density dependent but that other factors can be involved, such as shape or deformity. Moreover, peak profile description parameters (standard deviation and asymmetry) can be qualitatively related to some biophysical parameters. Numerous elution characteristics can be linked to cell properties described in the literature and although GFFF appeared to have limited capabilities in terms of size analysis it appeared to be a versatile tool for studying cell biophysical characteristics.

  11. High power density microbial fuel cell with flexible 3D graphene-nickel foam as anode

    Wang, Hanyu; Wang, Gongming; Ling, Yichuan; Qian, Fang; Song, Yang; Lu, Xihong; Chen, Shaowei; Tong, Yexiang; Li, Yat


    The structure and electrical conductivity of anode play a significant role in the power generation of microbial fuel cells (MFCs). In this study, we developed a three-dimensional (3D) reduced graphene oxide-nickel (denoted as rGO-Ni) foam as an anode for MFC through controlled deposition of rGO sheets onto the nickel foam substrate. The loading amount of rGO sheets and electrode surface area can be controlled by the number of rGO loading cycles. 3D rGO-Ni foam anode provides not only a large accessible surface area for microbial colonization and electron mediators, but also a uniform macro-porous scaffold for effective mass diffusion of the culture medium. Significantly, at a steady state of the power generation, the MFC device with flexible rGO-Ni electrodes produced an optimal volumetric power density of 661 W m-3 calculated based on the volume of anode material, or 27 W m-3 based on the volume of the anode chamber. These values are substantially higher than that of plain nickel foam, and other conventional carbon based electrodes (e.g., carbon cloth, carbon felt, and carbon paper) measured in the same conditions. To our knowledge, this is the highest volumetric power density reported for mL-scale MFC device with a pure strain of Shewanella oneidensis MR-1. We also demonstrated that the MFC device can be operated effectively in a batch-mode at least for a week. These new 3D rGO-Ni electrodes show great promise for improving the power generation of MFC devices.The structure and electrical conductivity of anode play a significant role in the power generation of microbial fuel cells (MFCs). In this study, we developed a three-dimensional (3D) reduced graphene oxide-nickel (denoted as rGO-Ni) foam as an anode for MFC through controlled deposition of rGO sheets onto the nickel foam substrate. The loading amount of rGO sheets and electrode surface area can be controlled by the number of rGO loading cycles. 3D rGO-Ni foam anode provides not only a large accessible

  12. Serum amyloid A stimulates macrophage foam cell formation via lectin-like oxidized low-density lipoprotein receptor 1 upregulation

    Lee, Ha Young, E-mail: [Department of Biological Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Mitochondria Hub Regulation Center, Dong-A University, Busan 602-714 (Korea, Republic of); Kim, Sang Doo [Department of Biological Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Baek, Suk-Hwan [Department of Biochemistry and Molecular Biology, College of Medicine, Yeungnam University, Daegu 705-717 (Korea, Republic of); Choi, Joon Hyuk [Department of Pathology, College of Medicine, Yeungnam University, Daegu 705-717 (Korea, Republic of); Cho, Kyung-Hyun [School of Biotechnology, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Zabel, Brian A. [Palo Alto Institute for Research and Education, Veterans Affairs Hospital, Palo Alto, CA 94304 (United States); Bae, Yoe-Sik, E-mail: [Department of Biological Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Mitochondria Hub Regulation Center, Dong-A University, Busan 602-714 (Korea, Republic of); Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 135-710 (Korea, Republic of)


    Highlights: ► SAA induced macrophage foam cell formation. ► SAA stimulated upregulation of lectin-like oxidized low-density lipoprotein receptor 1 (LOX1). ► SAA-induced LOX1 expression and foam cell formation is mediated by JNK/NF-κB signaling. ► HDL-conjugated SAA also stimulates foam cell formation via LOX1 upregulation. ► The finding reveals a novel mechanism of action of SAA in the pathogenesis of atherosclerosis. -- Abstract: Elevated levels of serum amyloid A (SAA) is a risk factor for cardiovascular diseases, however, the role of SAA in the pathophysiology of atherosclerosis remains unclear. Here we show that SAA induced macrophage foam cell formation. SAA-stimulated foam cell formation was mediated by c-jun N-terminal kinase (JNK) signaling. Moreover, both SAA and SAA-conjugated high density lipoprotein stimulated the expression of the important scavenger receptor lectin-like oxidized low-density lipoprotein receptor 1 (LOX1) via nuclear factor-κB (NF-κB). A LOX1 antagonist carrageenan significantly blocked SAA-induced foam cell formation, indicating that SAA promotes foam cell formation via LOX1 expression. Our findings therefore suggest that SAA stimulates foam cell formation via LOX1 induction, and thus likely contributes to atherogenesis.

  13. Maximum information photoelectron metrology

    Hockett, P; Wollenhaupt, M; Baumert, T


    Photoelectron interferograms, manifested in photoelectron angular distributions (PADs), are a high-information, coherent observable. In order to obtain the maximum information from angle-resolved photoionization experiments it is desirable to record the full, 3D, photoelectron momentum distribution. Here we apply tomographic reconstruction techniques to obtain such 3D distributions from multiphoton ionization of potassium atoms, and fully analyse the energy and angular content of the 3D data. The PADs obtained as a function of energy indicate good agreement with previous 2D data and detailed analysis [Hockett et. al., Phys. Rev. Lett. 112, 223001 (2014)] over the main spectral features, but also indicate unexpected symmetry-breaking in certain regions of momentum space, thus revealing additional continuum interferences which cannot otherwise be observed. These observations reflect the presence of additional ionization pathways and, most generally, illustrate the power of maximum information measurements of th...

  14. Physiological conditions conducive to high cell density and high cyanophycin content in Ralstonia eutropha strain H16 possessing a KDPG aldolase gene-dependent addiction system.

    Lin, Kaichien; Elbahloul, Yasser; Steinbüchel, Alexander


    The recombinant strain of Ralstonia eutropha H16-PHB(-)4-∆eda (pBBR1MCS-2::cphA (6308)/eda (H16)) presenting a 2-keto-3-desoxy-phosphogluconate (KDPG) aldolase (eda) gene-dependent catabolic addiction system for plasmid maintenance when using gluconate or fructose as sole carbon source was used in this study. The effects of the initial pH, the nitrogen-to-carbon ratio, the inorganic components of medium, the oxygen supply, and the different carbon and nitrogen sources on the cell dry matter (CDM) and the cyanophycin granule polypeptide (CGP) content of the cells were studied in a mineral salts medium (MSM) without any additional amino acids or CGP precursor substrates. The experiments were designed to systematically find out the optimal conditions for growth of cells to high densities and for high CGP contents of the cells. Maximum contents of water-insoluble CGP and water-soluble CGP, contributing to 47.5% and 5.8% (w/w) of CDM, respectively, were obtained at the 30-L scale cultivation when cells were cultivated in MSM medium containing sufficient supplements of fructose, NH(3), K(2)SO(4), MgSO(4)[Symbol: see text]7H(2)O, Fe(Ш)NH(4)-citrate, CaCl(2)[Symbol: see text]2H(2)O, and trace elements (SL6). The molecular masses of water-insoluble and water-soluble CGP ranged from 25 to 31 kDa and from 15 to 21 kDa, respectively. High cell densities of up to 82.8 g CDM/L containing up to 37.8% (w/w) water-insoluble CGP at the 30-L scale cultivation were also obtained. This is by far the best combination of high cell density and high cellular CGP contents ever reported, and it showed that efficient production of CGP at the industrial scale in white biotechnology could be achieved.

  15. [A sharp increase in the density of pulmonary and pericardial mast cells under monocrotaline-induced pulmonary hypertension in rats].

    Erokhina, I L; Okovityĭ, S V; Kazachenko, A A; Kulikov, A N; Emel'ianova, O I; Bystrova, O A


    Multifunctional granular mast cells (MCs) are involved in various pathological processes. The response of MC populations of myocardium, pericardium and lung to pulmonary hypertension (PH) has been studies 8 weeks after injection of monocrotaline. Five intact and five experimental rats were used. The density of MCs of different maturity was estimated on paraffin sections stained with Alcian blue and Safranin. Expressiveness of PH was estimated by functional parameters with the help of echocardiograms and by morphological markers. The MC density in myocardium of the intact and experimental rats was relatively low: 2 to 4 cells/mm2. MC density in the pericardium of intact rats was 14 times higher than in myocardium and increased 3 times for PH. The mature Safranin-positive cells predominated (70-80%) in myocardium and pericardium of intact and experimental rats. The MC density in the lungs of intact rats was about 30 cells/mm2; 98% of these cells were immature Alcian-positive cells. The mean density of MCs in the lungs of rats with PH increased 5.6 times. The mature Safranin-positive cells appeared in the lungs of rats with severe pathology. The greatest number of MCs in lungs was in the rats with the most pronounced disorders of myocardium function and marked histological damages (injuries) of myocardium and lungs. The finding show active response of MC population to monocrotaline-induced PH that stimulates migration of immature MCs into pericardium and lungs from the outside. Our data indicate the important role of MCs in the pathogenesis of PH.

  16. Improved probiotic viability in stress environments with post-culture of alginate-chitosan microencapsulated low density cells.

    Song, Huiyi; Yu, Weiting; Liu, Xiudong; Ma, Xiaojun


    In this study, probiotics (Saccharomyces cerevisiae Y235) were entrapped in alginate-chitosan microcapsules by emulsification/internal gelation technique. Two different encapsulation patterns were established as directly entrapped high density cells (dEHDC) and entrapped low density cells with culture (ELDCwc). The performance of microencapsulated cells, with free cells (FC) as control, was investigated against sequential stress environments of freeze-drying, storage, and simulated gastrointestinal fluids. After being freeze-dried without cryoprotectant, the survival rate of ELDCwc (14.33%) was significantly higher than 10.00% of dEHDC, and 0.05% of FC. The lower temperature (-20°C) and ELDCwc pattern were beneficial for keeping viable cells at 7.00 logCFU g(-1) after 6 months. Furthermore, the ELDCwc microcapsule maintained viable cells of 6.29 logCFU g(-1) after incubation in SGF and SIF. These studies demonstrated that the pattern of entrapped low density cells with culture was an effective and superior technique of resisting harmful stress environments. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Increased Chromogranin A Cell Density in the Large Intestine of Patients with Irritable Bowel Syndrome after Receiving Dietary Guidance

    Tarek Mazzawi


    Full Text Available The large intestine contains five types of endocrine cells that regulate its functions by sensing its luminal contents and releasing specific hormones. Chromogranin A (CgA is a common marker for the gastrointestinal endocrine cells, and it is abnormal in irritable bowel syndrome (IBS patients. Most IBS patients relate their symptoms to certain food elements. The present study investigated the effect of dietary guidance on the total endocrine cells of the large intestine as detected by CgA in 13 IBS patients. Thirteen control subjects were also included. Each patient received three sessions of dietary guidance. Colonoscopies were performed on controls and patients (at baseline and at 3–9 months after receiving guidance. Biopsy samples from the colon and rectum were immunostained for CgA and quantified by computerized image analysis. The densities of CgA cells in the total colon (mean ± SEM among the controls and the IBS patients before and after receiving dietary guidance were 83.3±10.1, 38.6±3.7, and 64.7±4.2 cells/mm2, respectively (P=0.0004, and were unchanged in the rectum. In conclusion, the increase in CgA cell density after receiving dietary guidance may reflect a change in the densities of the large intestinal endocrine cells causing an improvement in the IBS symptoms.

  18. Carbamylated low-density lipoprotein induces oxidative stress and accelerated senescence in human endothelial progenitor cells.

    Carracedo, Julia; Merino, Ana; Briceño, Carolina; Soriano, Sagrario; Buendía, Paula; Calleros, Laura; Rodriguez, Mariano; Martín-Malo, Alejandro; Aljama, Pedro; Ramírez, Rafael


    Carbamylated low-density lipoprotein (cLDL) plays a role in atherosclerosis. In this study we evaluate the effect of uremia on LDL carbamylation and the effect of cLDL and oxidized LDL (oxLDL; 200 μg/ml) on number, function, and genomic stability of endothelial progenitor cells (EPCs) obtained from healthy volunteers. cLDL was generated after incubation of native LDL (nLDL) with uremic serum from patients with chronic kidney disease (CKD) stages 2-4. Oxidative stress was measured by flow cytometry and fluorescent microscopy, mitochondrial depolarization by flow cytometry, senescence by β-galactosidase activity and telomere length, and DNA damage by phosphorylated histone H2AX (γH2AX). The percentage of cLDL by uremic serum was related to the severity of CKD. Compared with nLDL, cLDL induced an increase in oxidative stress (62±5 vs. 8±3%, P<0.001) and cells with mitochondrial depolarization (73±7 vs. 9±5%, P<0.001), and a decrease in EPC proliferation and angiogenesis. cLDL also induced accelerated senescence (73±16 vs. 12±9%, P<0.001), which was associated with a decrease in the expression of γH2AX (62±9 vs. 5±3%, P<0.001). The degree of injury induced by cLDL was comparable to that observed with oxLDL. This study supports the hypothesis that cLDL triggers genomic damage in EPCs, resulting in premature senescence. We can, therefore, hypothesize that EPCs injury by cLDL contributes to an increase in atherosclerotic disease in CKD.

  19. Argyrophil cell density in the oxyntic mucosa is higher in female than in male morbidly obese patients

    Maksud, F.A.N. [Laboratório de Patologia Digestiva e Neuroendócrina, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Faculdade de Medicina, Universidade Federal de Ouro Preto, Ouro Preto, MG (Brazil); Kakehasi, A.M. [Laboratório de Patologia Digestiva e Neuroendócrina, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Barbosa, A.J.A. [Laboratório de Patologia Digestiva e Neuroendócrina, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Instituto Alfa de Gastroenterologia, Belo Horizonte, MG (Brazil)


    Obesity is a multifactorial disorder often associated with many important diseases such as diabetes, hypertension and other metabolic syndrome conditions. Argyrophil cells represent almost the total population of endocrine cells of the human gastric mucosa and some reports have described changes of specific types of these cells in patients with obesity and metabolic syndrome. The present study was designed to evaluate the global population of argyrophil cells of the gastric mucosa of morbidly obese and dyspeptic non-obese patients. Gastric biopsies of antropyloric and oxyntic mucosa were obtained from 50 morbidly obese patients (BMI >40) and 50 non-obese patients (17 dyspeptic overweight and 33 lean individuals) and processed for histology and Grimelius staining for argyrophil cell demonstration. Argyrophil cell density in the oxyntic mucosa of morbidly obese patients was higher in female (238.68 ± 83.71 cells/mm{sup 2}) than in male patients (179.31 ± 85.96 cells/mm{sup 2}) and also higher in female (214.20 ± 50.38 cells/mm{sup 2}) than in male (141.90 ± 61.22 cells/mm{sup 2}) morbidly obese patients with metabolic syndrome (P = 0.01 and P = 0.02, respectively). In antropyloric mucosa, the main difference in argyrophil cell density was observed between female morbidly obese patients with (167.00 ± 69.30 cells/mm{sup 2}) and without (234.00 ± 69.54 cells/mm{sup 2}) metabolic syndrome (P = 0.001). In conclusion, the present results show that the number of gastric argyrophil cells could be under gender influence in patients with morbid obesity. In addition, gastric argyrophil cells seem to behave differently among female morbidly obese patients with and without metabolic syndrome.

  20. Control of morphology and defect density in zinc oxide for improved dye-sensitized solar cells.

    Kim, Seul Ah; Abbas, Muhammad Awais; Lee, Lanlee; Kang, Byungwuk; Kim, Hahkjoon; Bang, Jin Ho


    While zinc oxide (ZnO) with a mesoporous network has long been explored for adsorption of dyes and as an electron-transporting medium in dye-sensitized solar cells (DSSCs), the performance of ZnO-based DSSCs remains unsatisfactory. Despite the importance of understanding the surface characteristics of ZnO in DSSC applications, most of the studies relevant to ZnO-based DSSCs are focused on the synthesis of unique nanostructures of ZnO. In this study, we not only introduce a novel disk-shaped ZnO nanostructure, but also provide insight into the distinctive surface properties of ZnO and its influence on DSSC performance. When utilized in DSSCs, the mesoporous ZnO nanodisk yields 60% better power conversion efficiency (PCE) compared to commercial ZnO nanoparticles, which is attributed to less surface and bulk trap densities as concluded by an in-depth open-circuit voltage decay (OCVD) analysis and electrochemical impedance spectroscopy (EIS). Another aspect that contributes to the higher PCE is the better connectivity of primary particles that join together to form secondary disk-shaped particles. Furthermore, a 40% improvement in the PCE was observed by coating the mesoporous ZnO nanodisk with TiO2, which results from the passivation of the surface defects that aid in suppressing the interfacial charge recombination.

  1. Pterygium is related to a decrease in corneal endothelial cell density.

    Hsu, Min-Yen; Lee, Hsin-Nung; Liang, Chiao-Ying; Wei, Li-Chen; Wang, Chun-Yuan; Lin, Keng-Hung; Shen, Ying-Cheng


    The aim of this study was to investigate the relationship between pterygium and a decrease in the corneal endothelial cell density (ECD) in patients with unilateral primary pterygium. In this retrospective cross-sectional study, 90 consecutive patients with unilateral primary pterygium were enrolled from January 2010 to June 2012. Corneal ECD was measured in both eyes, and the fellow eyes were considered as controls. The relationship between the percentage of pterygium to cornea and a decrease in the ECD was analyzed. An increase in astigmatism in eyes with pterygium was evaluated for association with decreased ECD using the Pearson correlation test. The percentage of pterygium to cornea ranged from 3.5% to 65.2%, with a median of 12.35%. The difference in the corneal ECD between eyes with pterygium and control eyes ranged from +9.6% to -37.7%, with a median of -9.75%. The results of the Pearson correlation statistical test showed a strong logarithmic correlation between a decrease in the corneal ECD and the percentage of pterygium to cornea (R = 0.688, P decrease in the ECD in eyes with pterygium. Pterygium is related to a decrease in corneal ECD. Surgical intervention should be considered in patients with extensive pterygium involvement in the cornea or a significant increase in astigmatism.

  2. Coumarin Dyes for Dye-Sensitized Solar Cells - A Long-Range-Corrected Density Functional Study

    Wong, Bryan M; 10.1063/1.3025924


    The excited-state properties in a series of coumarin solar cell dyes are investigated with a long-range-corrected (LC) functional which asymptotically incorporates Hartree-Fock exchange. Using time-dependent density functional theory (TDDFT), we calculate excitation energies, oscillator strengths, and excited-state dipole moments in each of the dyes as a function of the range-separation paramenter, mu. To investigate the acceptable range of mu and assess the quality of the LC-TDDFT formalism, an extensive comparison is made between LC-BLYP excitation energies and approximate coupled cluster singles and doubles (CC2) calculations. When using a properly-optimized value of mu, we find that the LC technique provides a consistent picture of charge-transfer excitations as a function of molecular size. In contrast, we find that the widely-used B3LYP hybrid functional severely overestimates excited-state dipole moments and underestimates vertical excitations energies, especially for larger dye molecules. The results ...

  3. Time dependent – density functional theory characterization of organic dyes for dye-sensitized solar cells

    Hilal, Rifaat


    We aim at providing better insight into the parameters that govern the intramolecular charge transfer (ICT) and photo-injection processes in dyes for dye-sensitised solar cells (DSSC). Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations are utilized to study the geometry, electronic structure, electrostatic potential (ESP) and absorption spectrum, for a representative donor-π bridge-acceptor (D–π–A) dye for DSSC. The coplanar geometry of the dye (D1) facilitates strong conjugation and considerable delocalization originating the π CT interaction from donor to acceptor orbitals and the hyper-conjugative interactions involving Rydberg states. A model simulating the adsorption of the dye on the TiO surface is utilized to estimate binding energies. The effect of fluorine substituents in the π-spacer on the quantum efficiency of DSSCs was investigated. Gibb’s free energy values, redox potentials, excited state lifetime, non-linear optical properties (NLO) and driving forces for D1 and its fluorinated derivatives were computed.


    Phifer, M.


    It is anticipated that high density polyethylene (HDPE) geomembranes will be utilized within the liner and closure cap of the proposed On-Site Disposal Cell (OSDC) at the Portsmouth Gaseous Diffusion Plant. The likely longevity (i.e. service life) of HDPE geomembranes in OSDC service is evaluated within the following sections of this report: (1) Section 2.0 provides an overview of HDPE geomembranes, (2) Section 3.0 outlines potential HDPE geomembranes degradation mechanisms, (3) Section 4.0 evaluates the applicability of HDPE geomembrane degradation mechanisms to the Portsmouth OSDC, (4) Section 5.0 provides a discussion of the current state of knowledge relative to the longevity (service life) of HDPE geomembranes, including the relation of this knowledge to the Portsmouth OSDC, and (5) Section 6.0 provides summary and conclusions relative to the anticipated service life of HDPE geomembranes in OSDC service. Based upon this evaluation it is anticipated that the service life of HDPE geomembranes in OSDC service would be significantly greater than the 200 year service life assumed for the OSDC closure cap and liner HDPE geomembranes. That is, a 200 year OSDC HDPE geomembrane service life is considered a conservative assumption.

  5. Changes of the ganglioside pattern and content in human fibroblasts by high density cell population subculture progression.

    Sciannamblo, Mariateresa; Chigorno, Vanna; Passi, Alberto; Valaperta, Rea; Zucchi, Ileana; Sonnino, Sandro


    In this study we show that the ganglioside content and pattern of human skin fibroblasts change along the process of cell subculture progression by varying the cell density. GM3, GD3 and GD1a were components of the total cell ganglioside mixtures extracted from cells, but GD1a was in all the extracts a minor component or very scant. Other gangliosides present in traces were not characterised. The fibroblast ganglioside content of 52 pools of cells obtained from 5 different cell lines cultured at variable cell density ranged from 2.0 to 13.1 nmoles per mg of cell protein. The molar ratio between GM3 and GD3 varied from 418 to 0.6 in the ganglioside mixtures, as determined by densitometric quantitative analysis after thin layer chromatographic separation. Both the ganglioside content and the GM3/GD3 molar ratio were constant along several passages of subculture progression performed by plating cells collected at confluence. Instead, when the subculture progression was performed by plating cells collected at a few days after reaching confluence, a progressive increase of the ganglioside content was observed. GD3 increased proportionally more than GM3 so that a progressive decrease of the ratio between GM3 and GD3 was observed. In some experiments, GD3 was very scant at the beginning of the progression, while it was near 30% after 5 passages under these conditions. The progressive increase of GD3 along the high density cell population subculture progression was associated to a moderate increase of the mRNA GD3 synthase.

  6. Assumed white blood cell count of 8,000 cells/μL overestimates malaria parasite density in the Brazilian Amazon.

    Eduardo R Alves-Junior

    Full Text Available Quantification of parasite density is an important component in the diagnosis of malaria infection. The accuracy of this estimation varies according to the method used. The aim of this study was to assess the agreement between the parasite density values obtained with the assumed value of 8,000 cells/μL and the automated WBC count. Moreover, the same comparative analysis was carried out for other assumed values of WBCs. The study was carried out in Brazil with 403 malaria patients who were infected in different endemic areas of the Brazilian Amazon. The use of a fixed WBC count of 8,000 cells/μL to quantify parasite density in malaria patients led to overestimated parasitemia and resulted in low reliability when compared to the automated WBC count. Assumed values ranging between 5,000 and 6,000 cells/μL, and 5,500 cells/μL in particular, showed higher reliability and more similar values of parasite density when compared between the 2 methods. The findings show that assumed WBC count of 5,500 cells/μL could lead to a more accurate estimation of parasite density for malaria patients in this endemic region.

  7. Maximum Likelihood Associative Memories

    Gripon, Vincent; Rabbat, Michael


    Associative memories are structures that store data in such a way that it can later be retrieved given only a part of its content -- a sort-of error/erasure-resilience property. They are used in applications ranging from caches and memory management in CPUs to database engines. In this work we study associative memories built on the maximum likelihood principle. We derive minimum residual error rates when the data stored comes from a uniform binary source. Second, we determine the minimum amo...

  8. Maximum likely scale estimation

    Loog, Marco; Pedersen, Kim Steenstrup; Markussen, Bo


    A maximum likelihood local scale estimation principle is presented. An actual implementation of the estimation principle uses second order moments of multiple measurements at a fixed location in the image. These measurements consist of Gaussian derivatives possibly taken at several scales and....../or having different derivative orders. Although the principle is applicable to a wide variety of image models, the main focus here is on the Brownian model and its use for scale selection in natural images. Furthermore, in the examples provided, the simplifying assumption is made that the behavior...... of the measurements is completely characterized by all moments up to second order....

  9. Development and application of a membrane cyclone reactor for in vivo NMR spectroscopy with high microbial cell densities.

    Hartbrich, A; Schmitz, G; Weuster-Botz, D; de Graaf, A A; Wandrey, C


    A new bioreactor system has been developed for in vivo NMR spectroscopy of microorganisms under defined physiological conditions. This cyclone reactor with an integrated NMR flow cell is continuously operated in the magnet of a 400-MHz wide-bore NMR spectrometer system. The residence times of medium and cells are decoupled by a circulation-integrated cross-flow microfiltration module to achieve higher cell densities as compared to continuous fermentations without cell retention (increase in cell density up to a factor of 10 in steady state). Volumetric mass transfer coefficients k(L)a of more than 1.0 s(-1) are possible in the membrane cyclone reactor, ensuring adequate oxygen supply [oxygen transfer rate >15,000 mg O(2) .(L h)(-1)] of high cell densities. With the aid of the membrane cyclone reactor we were able to show, using continuous in vivo (31)P NMR spectroscopy of anaerobic glucose fermentation by Zymomonas mobilis, that the NMR signal intensity was directly proportional to the cell concentration in the reactor. The concentration profiles of intracellular inorganic phosphate, NAD(H), NDP, NTP, UDP-sugar, a cyclic pyrophosphate, two sugar phosphate pools, and extracellular inorganic phosphate were recorded after a shift from one steady state to another. The intracellular cyclic pyrophosphate had not been detected before in in vitro measurements of Zymomonas mobilis extracts due to the high instability of this compound. Using continuous in vivo (13)C NMR spectroscopy of aerobic glucose utilization by Corynebacterium glutamicum at a density of 25 g(cell dry weight) . L(-1), the membrane cyclone reactor served to measure the different dynamics of labeling in the carbon atoms of L-lactate, L-glutamate, succinate, and L-lysine with a time resolution of 10 min after impressing a [1-(13)C]-glucose pulse.

  10. High cell density cultivation of recombinant yeasts and bacteria under non-pressurized and pressurized conditions in stirred tank bioreactors.

    Knoll, Arnd; Bartsch, Stefan; Husemann, Bernward; Engel, Philip; Schroer, Kirsten; Ribeiro, Betina; Stöckmann, Christoph; Seletzky, Juri; Büchs, Jochen


    This study demonstrates the applicability of pressurized stirred tank bioreactors for oxygen transfer enhancement in aerobic cultivation processes. The specific power input and the reactor pressure was employed as process variable. As model organism Escherichia coli, Arxula adeninivorans, Saccharomyces cerevisiae and Corynebacterium glutamicum were cultivated to high cell densities. By applying specific power inputs of approx. 48kWm(-3) the oxygen transfer rate of a E. coli culture in the non-pressurized stirred tank bioreactor was lifted up to values of 0.51moll(-1)h(-1). When a reactor pressure up to 10bar was applied, the oxygen transfer rate of a pressurized stirred tank bioreactor was lifted up to values of 0.89moll(-1)h(-1). The non-pressurized stirred tank bioreactor was able to support non-oxygen limited growth of cell densities of more than 40gl(-1) cell dry weight (CDW) of E. coli, whereas the pressurized stirred tank bioreactor was able to support non-oxygen limited growth of cell densities up to 225gl(-1) CDW of A. adeninivorans, 89gl(-1) CDW of S. cerevisiae, 226gl(-1) CDW of C. glutamicum and 110gl(-1) CDW of E. coli. Compared to literature data, some of these cell densities are the highest values ever achieved in high cell density cultivation of microorganisms in stirred tank bioreactors. By comparing the specific power inputs as well as the k(L)a values of both systems, it is demonstrated that only the pressure is a scaleable tool for oxygen transfer enhancement in industrial stirred tank bioreactors. Furthermore, it was shown that increased carbon dioxide partial pressures did not remarkably inhibit the growth of the investigated model organisms.

  11. Cdc45 limits replicon usage from a low density of preRCs in mammalian cells.

    Wong, Philip G; Winter, Sherry L; Zaika, Elena; Cao, Thinh V; Oguz, Umut; Koomen, John M; Hamlin, Joyce L; Alexandrow, Mark G


    Little is known about mammalian preRC stoichiometry, the number of preRCs on chromosomes, and how this relates to replicon size and usage. We show here that, on average, each 100-kb of the mammalian genome contains a preRC composed of approximately one ORC hexamer, 4-5 MCM hexamers, and 2 Cdc6. Relative to these subunits, ∼0.35 total molecules of the pre-Initiation Complex factor Cdc45 are present. Thus, based on ORC availability, somatic cells contain ∼70,000 preRCs of this average total stoichiometry, although subunits may not be juxtaposed with each other. Except for ORC, the chromatin-bound complement of preRC subunits is even lower. Cdc45 is present at very low levels relative to the preRC subunits, but is highly stable, and the same limited number of stable Cdc45 molecules are present from the beginning of S-phase to its completion. Efforts to artificially increase Cdc45 levels through ectopic expression block cell growth. However, microinjection of excess purified Cdc45 into S-phase nuclei activates additional replication foci by three-fold, indicating that Cdc45 functions to activate dormant preRCs and is rate-limiting for somatic replicon usage. Paradoxically, although Cdc45 colocalizes in vivo with some MCM sites and is rate-limiting for DNA replication to occur, neither Cdc45 nor MCMs colocalize with active replication sites. Embryonic metazoan chromatin consists of small replicons that are used efficiently via an excess of preRC subunits. In contrast, somatic mammalian cells contain a low density of preRCs, each containing only a few MCMs that compete for limiting amounts of Cdc45. This provides a molecular explanation why, relative to embryonic replicon dynamics, somatic replicons are, on average, larger and origin efficiency tends to be lower. The stable, continuous, and rate-limiting nature of Cdc45 suggests that Cdc45 contributes to the staggering of replicon usage throughout S-phase, and that replicon activation requires reutilization of



    Studies with synchronized or exponentially growing bacteria and mammalian cell lines are not able to demonstrate small changes in buoyant density during the cell cycle. Flowcytometric analysis of density separated acute myeloid leukemia cells, a system not dependent on time-related variables, shows




    Studies with synchronized or exponentially growing bacteria and mammalian cell lines are not able to demonstrate small changes in buoyant density during the cell cycle. Flowcytometric analysis of density separated acute myeloid leukemia cells, a system not dependent on time-related variables, shows

  14. Paraffin oil as a "methane vector" for rapid and high cell density cultivation of Methylosinus trichosporium OB3b.

    Han, Bing; Su, Tao; Wu, Hao; Gou, Zhongxuan; Xing, Xin-Hui; Jiang, Hao; Chen, Yin; Li, Xin; Murrell, J Colin


    Slow growth and relatively low cell densities of methanotrophs have limited their uses in industrial applications. In this study, a novel method for rapid cultivation of Methylosinus trichosporium OB3b was studied by adding a water-immiscible organic solvent in the medium. Paraffin oil was the most effective at enhancing cell growth and final cell density. This is at least partially due to the increase of methane gas transfer between gas and medium phases since methane solubility is higher in paraffin than in water/nitrate minimal salt medium. During cultivation with paraffin oil at 5% (v/v) in the medium, M. trichosporium OB3b cells also showed higher concentrations of the intermediary metabolites, such as formic acid and pyruvic acid, and consumed more methane compared with the control. Paraffin as methane vector to improve methanotroph growth was further studied in a 5-L fermentor at three concentrations (i.e., 2.5%, 5%, and 10%). Cell density reached about 14 g dry weight per liter with 5% paraffin, around seven times higher than that of the control (without paraffin). Cells cultivated with paraffin tended to accumulate around the interface between oil droplets and the water phase and could exist in oil phase in the case of 10% (v/v) paraffin. These results indicated that paraffin could enhance methanotroph growth, which is potentially useful in cultivation of methanotrophs in large scale in industry.

  15. Low densities of serotonin and peptide YY cells in the colon of patients with irritable bowel syndrome.

    El-Salhy, M; Gundersen, D; Ostgaard, H; Lomholt-Beck, B; Hatlebakk, J G; Hausken, T


    The gut hormones are important in regulating gastrointestinal motility. Disturbances in gastrointestinal motility have been reported in patients with irritable bowel syndrome (IBS). Reduced endocrine cell density, as revealed by chromogranin A, has been reported in the colon of IBS patients. To investigate a possible abnormality in the colonic endocrine cells of IBS patients. A total of 41 patients with IBS according to Rome Criteria III and 20 controls were included in the study. Biopsies from the right and left colon were obtained from both patients and controls during colonoscopy. The biopsies were immunostained for serotonin, peptide YY (PYY), pancreatic polypeptide (PP), entroglucagon, and somatostatin cells. Cell densities were quantified by computerized image analysis. Serotonin and PYY cell densities were reduced in the colon of IBS patients. PP, entroglucagon, and somatostatin-immunoreactive cells were too few to enable reliable quantification. The cause of these observations could be primary genetic defect(s), secondary to altered serotonin and/or PYY signaling systems and/or subclinical inflammation. Serotonin activates the submucosal sensory branch of the enteric nervous system and controls gastrointestinal motility and chloride secretion via interneurons and motor neurons. PYY stimulates absorption of water and electrolytes, and inhibits prostaglandin (PG) E2, and vasoactive intestinal peptide, which stimulates intestinal fluid secretion and is a major regulator of the "ileal brake". Although the cause and effect relationship of these findings is difficult to elucidate, the abnormalities reported here might contribute to the symptoms associated with IBS.

  16. Magnetic Resonance Imaging Detection of Tumor Cells by Targeting Low-Density Lipoprotein Receptors with Gd-Loaded Low-Density Lipoprotein Particles

    Simonetta Geninatti Crich


    Full Text Available Gd-DO3A-diph and Gd-AAZTAC17 are lipophilic magnetic resonance imaging (MRI agents that display high affinity for low-density lipoprotein (LDL particles. However, on binding to LDL, Gd-DO3A-diph shows a decreased hydration that results in a lower enhancement of water proton relaxation rate. Conversely, GdAAZTAC17 displays a strong relaxation enhancement at the imaging fields. Each LDL particle can load up to 100 and 400 UNITS of Gd-DO3A-diph and Gd-AAZTAC17, respectively. Their LDL adducts are taken up by human hepatoblastoma G2 (HepG2 and melanoma B16 tumor cells when added to the incubation medium. T, measurements of the labeled cells indicate that Gd-AAZTAC17 is significantly more efficient than Gd-DO3A-diph. Furthermore, it has been found that HepG2 hepatoma cells can internalize higher amounts of Gd-AAZTAC17 than B16 cells and the involvement of LDL receptors (LDLRs has been demonstrated in competition assays with free LDL. Gd-AAZTAC17/LDL adduct proved to be an efficient probe in the magnetic resonance (MR visualization of subcutaneous tumors in animal models obtained by injecting B16 melanoma cells into the right flank of mice. Finally, confocal microscopy validation of the distribution of LDL-based probes in the tumor has been obtained by doping the Gd-AAZTAC17/LDL adduct with a fluorescent phospholipid moiety.

  17. Developing high cell density fed-batch cultivation strategies for heterologous protein production in Pichia pastoris using the nitrogen source-regulated FLD1 Promoter.

    Resina, David; Cos, Oriol; Ferrer, Pau; Valero, Francisco


    A Pichia pastoris strain expressing a Rhizopus oryzae lipase gene under the transcriptional control of the promoter from the P. pastoris formaldehyde dehydrogenase 1 gene (PFLD) was utilized to study the feasibility of this expression system for recombinant protein production using methanol-free fed-batch high cell density cultivations. We have developed a simple and reliable fed-batch strategy using the PFLD system based on the use of methylamine and sorbitol as nitrogen and carbon sources, respectively, for the induction phase. Three different fed-batch fermentations were performed at three different constant growth rates, i.e., at a low growth rate (0.005/h), at an intermediate growth rate of (0.01/h), and at a constant residual sorbitol concentration of 8 g/L, i.e., allowing cells to grow at high (near micro(max)) growth rate (0.02/h). Important differences were observed between the lower and higher growth rate cultivation phases in terms of specific production rate (q(p)) profiles. In all three cases, maximum q(p) were reached soon after the start of the induction phase; after that maximum, an exponential decrease reaching final values close to zero were observed, except for the cells growing at near micro(max). The best results in terms of Y(P/X), productivity and specific productivity were obtained when the microorganism was growing at the highest growth rate. Furthermore, such results were significantly better in relation to those obtained with the PAOX-based system expressing the same protein.

  18. Syntrophic interactions between H2-scavenging and anode-respiring bacteria can improve current density in microbial electrochemical cells

    High current density of 10.0-14.6 A/m2 and COD removal up to 96% were obtained in a microbial electrochemical cell (MEC) fed with digestate at hydraulic retention time (HRT) of 4d and 8d. Volatile fatty acids became undetectable in MEC effluent (HRT 8d), except for trivial acetat...

  19. 3D characterization of EMT cell density in developing cardiac cushions using optical coherence tomography (Conference Presentation)

    Yu, Siyao; Gu, Shi; Zhao, Xiaowei; Liu, Yehe; Jenkins, Michael W.; Watanabe, Michiko; Rollins, Andrew M.


    Congenital heart defects (CHDs) are the most common birth defect, affecting between 4 and 75 per 1,000 live births depending on the inclusion criteria. Many of these defects can be traced to defects of cardiac cushions, critical structures during development that serve as precursors to many structures in the mature heart, including the atrial and ventricular septa, and all four sets of cardiac valves. Epithelial-mesenchymal transition (EMT) is the process through which cardiac cushions become populated with cells. Altered cushion size or altered cushion cell density has been linked to many forms of CHDs, however, quantitation of cell density in the complex 3D cushion structure poses a significant challenge to conventional histology. Optical coherence tomography (OCT) is a technique capable of 3D imaging of the developing heart, but typically lacks the resolution to differentiate individual cells. Our goal is to develop an algorithm to quantitatively characterize the density of cells in the developing cushion using 3D OCT imaging. First, in a heart volume, the atrioventricular (AV) cushions were manually segmented. Next, all voxel values in the region of interest were pooled together to generate a histogram. Finally, two populations of voxels were classified using either K-means classification, or a Gaussian mixture model (GMM). The voxel population with higher values represents cells in the cushion. To test the algorithm, we imaged and evaluated avian embryonic hearts at looping stages. As expected, our result suggested that the cell density increases with developmental stages. We validated the technique against scoring by expert readers.

  20. The prognostic implications of microvascular density and lymphatic vessel density in esophageal squamous cell carcinoma: Comparative analysis between the traditional whole sections and the tissue microarray.

    Chen, Bo; Fang, Wang-Kai; Wu, Zhi-Yong; Xu, Xiu-E; Wu, Jian-Yi; Fu, Jun-Hui; Yao, Xiao-Dong; Huang, Jian-Hao; Chen, Jie-Xin; Shen, Jin-Hui; Zheng, Chun-Peng; Wang, Shao-Hong; Li, En-Min; Xu, Li-Yan


    Focal distribution of microvascular and lymphatic vessels is a critical issue in cancer, and is measured by tissue microarray (TMA) construction from paraffin-embedded surgically obtained tissues, a process that may not accurately reflect true focal distribution. The aim of this study was to assess the concordance of microvascular density (MVD) and lymphatic vessel density (LVD) in TMAs with corresponding whole sections, and to correlate the MVD or LVD with clinicopathological parameters in 124 cases of esophageal squamous cell carcinoma (ESCC). MVD, determined by CD105 immunohistochemistry of whole sections, was strongly associated with lymph node metastasis (p=0.000) and pTNM stage (p=0.001). Kaplan-Meier survival analysis showed that increasing CD105 microvessel count correlated with decreasing survival (ptissue microarrays. Analysis of continuous data showed a highly significant correlation between whole sections and TMA data (Pearson r=0.522, p<0.001). Increasing LVD, as determined by D2-40 immunohistochemistry of whole sections, correlated with decreasing survival, but this relationship was undetectable using TMAs. In conclusion, we demonstrate that for the selected endothelial markers, TMAs can provide a realistic and reliable estimate of the extent of MVD, but not LVD in ESCC samples. Copyright © 2013 Elsevier GmbH. All rights reserved.

  1. Maximum Entropy Fundamentals

    F. Topsøe


    Full Text Available Abstract: In its modern formulation, the Maximum Entropy Principle was promoted by E.T. Jaynes, starting in the mid-fifties. The principle dictates that one should look for a distribution, consistent with available information, which maximizes the entropy. However, this principle focuses only on distributions and it appears advantageous to bring information theoretical thinking more prominently into play by also focusing on the "observer" and on coding. This view was brought forward by the second named author in the late seventies and is the view we will follow-up on here. It leads to the consideration of a certain game, the Code Length Game and, via standard game theoretical thinking, to a principle of Game Theoretical Equilibrium. This principle is more basic than the Maximum Entropy Principle in the sense that the search for one type of optimal strategies in the Code Length Game translates directly into the search for distributions with maximum entropy. In the present paper we offer a self-contained and comprehensive treatment of fundamentals of both principles mentioned, based on a study of the Code Length Game. Though new concepts and results are presented, the reading should be instructional and accessible to a rather wide audience, at least if certain mathematical details are left aside at a rst reading. The most frequently studied instance of entropy maximization pertains to the Mean Energy Model which involves a moment constraint related to a given function, here taken to represent "energy". This type of application is very well known from the literature with hundreds of applications pertaining to several different elds and will also here serve as important illustration of the theory. But our approach reaches further, especially regarding the study of continuity properties of the entropy function, and this leads to new results which allow a discussion of models with so-called entropy loss. These results have tempted us to speculate over

  2. Lipid Droplet Formation in HeLa Cervical Cancer Cells Depends on Cell Density and the Concentration of Exogenous Unsaturated Fatty Acids.

    Guštin, Ema; Jarc, Eva; Kump, Ana; Petan, Toni


    Cytosolic lipid droplets (LDs) store excess fatty acids (FAs) in the form of neutral lipids and prevent starvation-induced cancer cell death. Here we studied the ability of mono- and polyunsaturated FAs to affect LD formation and survival in HeLa cervical cancer cells. We found that the LD content in HeLa cells increases with cell density, but it decreases in MDA-MB-231 breast cancer cells. Exogenously-added unsaturated FAs, including oleic (OA), linoleic (LA), arachidonic (AA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) displayed a similar ability to alter LD formation in HeLa cells. There was a dual, concentration-dependent effect on neutral lipid accumulation: low micromolar concentrations of LA, AA and DHA reduced, while all FAs induced LD formation at higher concentrations. In serum starved He-La cells, OA stimulated LD formation, but, contrary to expectations, it promoted cell death. Our results reveal a link between cell population density and LD formation in HeLa cells and show that unsaturated FAs may both suppress or stimulate LD formation. This dynamic regulation of LD content must be accounted for when studying the effects of lipids and lipid metabolism-targeting drugs on LD metabolism in HeLa cells.

  3. The link between diffusion MRI and tumor heterogeneity: Mapping cell eccentricity and density by diffusional variance decomposition (DIVIDE).

    Szczepankiewicz, Filip; van Westen, Danielle; Englund, Elisabet; Westin, Carl-Fredrik; Ståhlberg, Freddy; Lätt, Jimmy; Sundgren, Pia C; Nilsson, Markus


    The structural heterogeneity of tumor tissue can be probed by diffusion MRI (dMRI) in terms of the variance of apparent diffusivities within a voxel. However, the link between the diffusional variance and the tissue heterogeneity is not well-established. To investigate this link we test the hypothesis that diffusional variance, caused by microscopic anisotropy and isotropic heterogeneity, is associated with variable cell eccentricity and cell density in brain tumors. We performed dMRI using a novel encoding scheme for diffusional variance decomposition (DIVIDE) in 7 meningiomas and 8 gliomas prior to surgery. The diffusional variance was quantified from dMRI in terms of the total mean kurtosis (MKT), and DIVIDE was used to decompose MKT into components caused by microscopic anisotropy (MKA) and isotropic heterogeneity (MKI). Diffusion anisotropy was evaluated in terms of the fractional anisotropy (FA) and microscopic fractional anisotropy (μFA). Quantitative microscopy was performed on the excised tumor tissue, where structural anisotropy and cell density were quantified by structure tensor analysis and cell nuclei segmentation, respectively. In order to validate the DIVIDE parameters they were correlated to the corresponding parameters derived from microscopy. We found an excellent agreement between the DIVIDE parameters and corresponding microscopy parameters; MKA correlated with cell eccentricity (r=0.95, pMKT parameter reflects both variable cell eccentricity and cell density, and therefore lacks specificity in terms of microstructure characteristics. However, specificity was obtained by decomposing the two contributions; MKA was associated only to cell eccentricity, and MKI only to cell density variance. The variance in meningiomas was caused primarily by microscopic anisotropy (mean±s.d.) MKA=1.11±0.33 vs MKI=0.44±0.20 (p<10(-3)), whereas in the gliomas, it was mostly caused by isotropic heterogeneity MKI=0.57±0.30 vs MKA=0.26±0.11 (p<0.05). In

  4. Regularized maximum correntropy machine

    Wang, Jim Jing-Yan


    In this paper we investigate the usage of regularized correntropy framework for learning of classifiers from noisy labels. The class label predictors learned by minimizing transitional loss functions are sensitive to the noisy and outlying labels of training samples, because the transitional loss functions are equally applied to all the samples. To solve this problem, we propose to learn the class label predictors by maximizing the correntropy between the predicted labels and the true labels of the training samples, under the regularized Maximum Correntropy Criteria (MCC) framework. Moreover, we regularize the predictor parameter to control the complexity of the predictor. The learning problem is formulated by an objective function considering the parameter regularization and MCC simultaneously. By optimizing the objective function alternately, we develop a novel predictor learning algorithm. The experiments on two challenging pattern classification tasks show that it significantly outperforms the machines with transitional loss functions.

  5. Myeloperoxidase-oxidized high density lipoprotein impairs atherosclerotic plaque stability by inhibiting smooth muscle cell migration.

    Zhou, Boda; Zu, Lingyun; Chen, Yong; Zheng, Xilong; Wang, Yuhui; Pan, Bing; Dong, Min; Zhou, Enchen; Zhao, Mingming; Zhang, Youyi; Zheng, Lemin; Gao, Wei


    High density lipoprotein (HDL) has been proved to be a protective factor for coronary heart disease. Notably, HDL in atherosclerotic plaques can be nitrated (NO2-oxHDL) and chlorinated (Cl-oxHDL) by myeloperoxidase (MPO), likely compromising its cardiovascular protective effects. Here we determined the effects of NO2-oxHDL and Cl-oxHDL on SMC migration using wound healing and transwell assays, proliferation using MTT and BrdU assays, and apoptosis using Annexin-V assay in vitro, as well as on atherosclerotic plaque stability in vivo using a coratid artery collar implantation mice model. Our results showed that native HDL promoted SMC proliferation and migration, whereas NO2-oxHDL and Cl-oxHDL inhibited SMC migration and reduced capacity of stimulating SMC proliferation as well as migration, respectively. OxHDL had no significant influence on SMC apoptosis. In addition, we found that ERK1/2-phosphorylation was significantly lower when SMCs were incubated with NO2-oxHDL and Cl-oxHDL. Furthermore, transwell experiments showed that differences between native HDL, NO2-oxHDL and Cl-oxHDL was abolished after PD98059 (MAPK kinase inhibitor) treatment. In aortic SMCs from scavenger receptor BI (SR-BI) deficient mice, differences between migration of native HDL, NO2-oxHDL and Cl-oxHDL treated SMCs vanished, indicating SR-BI's possible role in HDL-associated SMC migration. Importantly, NO2-oxHDL and Cl-oxHDL induced neointima formation and reduced SMC positive staining cells in atherosclerotic plaque, resulting in elevated vulnerable index of atherosclerotic plaque. These findings implicate MPO-catalyzed oxidization of HDL may contribute to atherosclerotic plaque instability by inhibiting SMC proliferation and migration through MAPK-ERK pathway which was dependent on SR-BI.

  6. Computational neuroanatomy: mapping cell-type densities in the mouse brain, simulations from the Allen Brain Atlas

    Grange, Pascal


    The Allen Brain Atlas of the adult mouse (ABA) consists of digitized expression profiles of thousands of genes in the mouse brain, co-registered to a common three-dimensional template (the Allen Reference Atlas).This brain-wide, genome-wide data set has triggered a renaissance in neuroanatomy. Its voxelized version (with cubic voxels of side 200 microns) is available for desktop computation in MATLAB. On the other hand, brain cells exhibit a great phenotypic diversity (in terms of size, shape and electrophysiological activity), which has inspired the names of some well-studied cell types, such as granule cells and medium spiny neurons. However, no exhaustive taxonomy of brain cell is available. A genetic classification of brain cells is being undertaken, and some cell types have been chraracterized by their transcriptome profiles. However, given a cell type characterized by its transcriptome, it is not clear where else in the brain similar cells can be found. The ABA can been used to solve this region-specificity problem in a data-driven way: rewriting the brain-wide expression profiles of all genes in the atlas as a sum of cell-type-specific transcriptome profiles is equivalent to solving a quadratic optimization problem at each voxel in the brain. However, the estimated brain-wide densities of 64 cell types published recently were based on one series of co-registered coronal in situ hybridization (ISH) images per gene, whereas the online ABA contains several image series per gene, including sagittal ones. In the presented work, we simulate the variability of cell-type densities in a Monte Carlo way by repeatedly drawing a random image series for each gene and solving the optimization problem. This yields error bars on the region-specificity of cell types.

  7. Catalysts for ultrahigh current density oxygen cathodes for space fuel cell applications

    Tryk, Donald A.; Yeager, E.


    The objective was to identify promising electrocatalyst/support systems for oxygen cathodes capable of operating at ultrahigh current densities in alkaline fuel cells. Such cells will require operation at relatively high temperatures and O2 pressures. A number of materials were prepared, including Pb-Ru and Pb-Ir pyrochlores, RuO2 and Pt-doped RuO2, lithiated NiO and La-Ni perovskites. Several of these materials were prepared using techniques that had not been previously used to prepare them. Particularly interesting was the use of the alkaline solution technique to prepare Pt-doped and Pb-Ru pyrochlores in high area form. Also interesting was the use of the fusion (melt) method for preparing the Pb-Ru pyrochlore. Several of the materials were also deposited with platinum. Well-crystallized Pb2Ru2O(7-y) was used to fabricate very high performance O2 cathodes with good stability in room temperature KOH. This material was also found to be stable over a useful potential range at approx. 140 C in concentrated KOH. For some of the samples, fabrication of the gas-fed electrodes could not be fully optimized during this project period. Future work may be directed at this problem. Pyrochlores that were not well-crystallized were found to be unstable in alkaline solution. Very good O2 reduction performance and stability were observed with Pb2RuO(7-y) in a carbon-based gas-fed electrode with an anion-conducting membrane placed on the electrolyte side of the electrode. The performance came within a factor of about two of that observed without carbon. High area platinum and gold supported on several conductive metal oxide supports were examined. Only small improvements in O2 reduction performance at room temperature were observed for Pb2Ru2O(7-y) as a support because of the high intrinsic activity of the pyrochlore. In contrast, a large improvement was observed for Li-doped NiO as a support for Pt. Very poor performance was observed for Au deposited on Li-NiO at approx. 150 C

  8. Interrogation of allelic chromatin states in human cells by high-density ChIP-genotyping.

    Light, Nicholas; Adoue, Véronique; Ge, Bing; Chen, Shu-Huang; Kwan, Tony; Pastinen, Tomi


    Allele-specific (AS) assessment of chromatin has the potential to elucidate specific cis-regulatory mechanisms, which are predicted to underlie the majority of the known genetic associations to complex disease. However, development of chromatin landscapes at allelic resolution has been challenging since sites of variable signal strength require substantial read depths not commonly applied in sequencing based approaches. In this study, we addressed this by performing parallel analyses of input DNA and chromatin immunoprecipitates (ChIP) on high-density Illumina genotyping arrays. Allele-specificity for the histone modifications H3K4me1, H3K4me3, H3K27ac, H3K27me3, and H3K36me3 was assessed using ChIP samples generated from 14 lymphoblast and 6 fibroblast cell lines. AS-ChIP SNPs were combined into domains and validated using high-confidence ChIP-seq sites. We observed characteristic patterns of allelic-imbalance for each histone-modification around allele-specifically expressed transcripts. Notably, we found H3K4me1 to be significantly anti-correlated with allelic expression (AE) at transcription start sites, indicating H3K4me1 allelic imbalance as a marker of AE. We also found that allelic chromatin domains exhibit population and cell-type specificity as well as heritability within trios. Finally, we observed that a subset of allelic chromatin domains is regulated by DNase I-sensitive quantitative trait loci and that these domains are significantly enriched for genome-wide association studies hits, with autoimmune disease associated SNPs specifically enriched in lymphoblasts. This study provides the first genome-wide maps of allelic-imbalance for five histone marks. Our results provide new insights into the role of chromatin in cis-regulation and highlight the need for high-depth sequencing in ChIP-seq studies along with the need to improve allele-specificity of ChIP-enrichment.

  9. Variation of carrier concentration and interface trap density in 8MeV electron irradiated c-Si solar cells

    Bhat, Sathyanarayana, E-mail:; Rao, Asha, E-mail: [Department of Physics, Mangalore Institute of Technology and Engineering, Moodabidri, Mangalore-574225 (India); Krishnan, Sheeja [Department of Physics, Sri Devi Institute of Technology, Kenjar, Mangalore-574142 (India); Sanjeev, Ganesh [Microtron Centre, Department of Physics, Mangalore University, Mangalagangothri-574199 (India); Suresh, E. P. [Solar Panel Division, ISRO Satellite Centre, Bangalore-560017 (India)


    The capacitance and conductance measurements were carried out for c-Si solar cells, irradiated with 8 MeV electrons with doses ranging from 5kGy – 100kGy in order to investigate the anomalous degradation of the cells in the radiation harsh environments. Capacitance – Voltage measurements indicate that there is a slight reduction in the carrier concentration upon electron irradiation due to the creation of radiation induced defects. The conductance measurement results reveal that the interface state densities and the trap time constant increases with electron dose due to displacement damages in c-Si solar cells.

  10. A High Power Density, High Efficiency Hydrogen-Chlorine Regenerative Fuel Cell with a Low Precious Metal Content Catalyst

    Huskinson, Brian; Rugolo, Jason; Mondal, Sujit K.; Aziz, Michael J.


    We report the performance of a hydrogen-chlorine electrochemical cell with a chlorine electrode employing a low precious metal content alloy oxide electrocatalyst for the chlorine electrode: (Ru_0.09Co_0.91)_3O_4. The cell employs a commercial hydrogen fuel cell electrode and transports protons through a Nafion membrane in both galvanic and electrolytic mode. The peak galvanic power density exceeds 1 W cm^-2, which is twice previous literature values. The precious metal loading of the chlorin...

  11. Suppressing lossy-film-induced angular mismatches between reflectance and transmittance extrema: optimum optical designs of interlayers and AR coating for maximum transmittance into active layers of CIGS solar cells.

    Chang, Yin-Jung


    The investigation of optimum optical designs of interlayers and antireflection (AR) coating for achieving maximum average transmittance (T(ave)) into the CuIn(1-x)Ga(x)Se2 (CIGS) absorber of a typical CIGS solar cell through the suppression of lossy-film-induced angular mismatches is described. Simulated-annealing algorithm incorporated with rigorous electromagnetic transmission-line network approach is applied with criteria of minimum average reflectance (R(ave)) from the cell surface or maximum T(ave) into the CIGS absorber. In the presence of one MgF2 coating, difference in R(ave) associated with optimum designs based upon the two distinct criteria is only 0.3% under broadband and nearly omnidirectional incidence; however, their corresponding T(ave) values could be up to 14.34% apart. Significant T(ave) improvements associated with the maximum-T(ave)-based design are found mainly in the mid to longer wavelengths and are attributed to the largest suppression of lossy-film-induced angular mismatches over the entire CIGS absorption spectrum. Maximum-T(ave)-based designs with a MgF2 coating optimized under extreme deficiency of angular information is shown, as opposed to their minimum-R(ave)-based counterparts, to be highly robust to omnidirectional incidence.

  12. Short-circuit current density imaging of crystalline silicon solar cells via lock-in thermography: Robustness and simplifications

    Fertig, Fabian, E-mail:; Greulich, Johannes; Rein, Stefan [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstr. 2, D-79110 Freiburg (Germany)


    Spatially resolved determination of solar cell parameters is beneficial for loss analysis and optimization of conversion efficiency. One key parameter that has been challenging to access by an imaging technique on solar cell level is short-circuit current density. This work discusses the robustness of a recently suggested approach to determine short-circuit current density spatially resolved based on a series of lock-in thermography images and options for a simplified image acquisition procedure. For an accurate result, one or two emissivity-corrected illuminated lock-in thermography images and one dark lock-in thermography image have to be recorded. The dark lock-in thermography image can be omitted if local shunts are negligible. Furthermore, it is shown that omitting the correction of lock-in thermography images for local emissivity variations only leads to minor distortions for standard silicon solar cells. Hence, adequate acquisition of one image only is sufficient to generate a meaningful map of short-circuit current density. Beyond that, this work illustrates the underlying physics of the recently proposed method and demonstrates its robustness concerning varying excitation conditions and locally increased series resistance. Experimentally gained short-circuit current density images are validated for monochromatic illumination in comparison to the reference method of light-beam induced current.

  13. Cell Density-Dependent Upregulation of PDCD4 in Keratinocytes and Its Implications for Epidermal Homeostasis and Repair

    Tao Wang


    Full Text Available Programmed cell death 4 (PDCD4 is one multi-functional tumor suppressor inhibiting neoplastic transformation and tumor invasion. The role of PDCD4 in tumorigenesis has attracted more attention and has been systematically elucidated in cutaneous tumors. However, the normal biological function of PDCD4 in skin is still unclear. In this study, for the first time, we find that tumor suppressor PDCD4 is uniquely induced in a cell density-dependent manner in keratinocytes. To determine the potential role of PDCD4 in keratinocyte cell biology, we show that knockdown of PDCD4 by siRNAs can promote cell proliferation in lower cell density and partially impair contact inhibition in confluent HaCaT cells, indicating that PDCD4 serves as an important regulator of keratinocytes proliferation and contact inhibition in vitro. Further, knockdown of PDCD4 can induce upregulation of cyclin D1, one key regulator of the cell cycle. Furthermore, the expression patterns of PDCD4 in normal skin, different hair cycles and the process of wound healing are described in detail in vivo, which suggest a steady-state regulatory role of PDCD4 in epidermal homeostasis and wound healing. These findings provide a novel molecular mechanism for keratinocytes’ biology and indicate that PDCD4 plays a role in epidermal homeostasis.

  14. Nanomodification of the electrodes in microbial fuel cell: impact of nanoparticle density on electricity production and microbial community

    Al Atraktchi, Fatima Al-Zahraa; Zhang, Yifeng; Angelidaki, Irini


    The nano-decoration of electrode with nanoparticles is one effective way to enhance power output of microbial fuel cells (MFCs). However, the amount of nanoparticles used for decoration has not been optimized yet, and how it affects the microbial community is still unknown. In this study, different....... Different densities of Au nanoparticles also resulted in different microbial communities on the anode. More diverse bacterial communities were found with higher Au nanoparticle densities. These results provide new dimensions in understanding electrode modification with nanoparticles in MFC systems....

  15. High relative density of lymphatic vessels predicts poor survival in tongue squamous cell carcinoma.

    Seppälä, Miia; Pohjola, Konsta; Laranne, Jussi; Rautiainen, Markus; Huhtala, Heini; Renkonen, Risto; Lemström, Karl; Paavonen, Timo; Toppila-Salmi, Sanna


    Tongue cancer has a poor prognosis due to its early metastasis via lymphatic vessels. The present study aimed at evaluating lymphatic vessel density, relative density of lymphatic vessel, and diameter of lymphatic vessels and its predictive role in tongue cancer. Paraffin-embedded tongue and lymph node specimens (n = 113) were stained immunohistochemically with a polyclonal antibody von Willebrand factor, recognizing blood and lymphatic endothelium and with a monoclonal antibody podoplanin, recognizing lymphatic endothelium. The relative density of lymphatic vessels was counted by dividing the mean number of lymphatic vessels per microscopic field (podoplanin) by the mean number of all vessels (vWf) per microscopic field. The high relative density of lymphatic vessels (≥80 %) was associated with poor prognosis in tongue cancer. The relative density of lymphatic vessels predicted poor prognosis in the group of primary tumor size T1-T2 and in the group of non-metastatic cancer. The lymphatic vessel density and diameter of lymphatic vessels were not associated with tongue cancer survival. The relative density of lymphatic vessels might have clinically relevant prognostic impact. Further studies with increased number of patients are needed.

  16. Equalized near maximum likelihood detector


    This paper presents new detector that is used to mitigate intersymbol interference introduced by bandlimited channels. This detector is named equalized near maximum likelihood detector which combines nonlinear equalizer and near maximum likelihood detector. Simulation results show that the performance of equalized near maximum likelihood detector is better than the performance of nonlinear equalizer but worse than near maximum likelihood detector.

  17. Human amniotic fluid stem cells support undifferentiated propagation and pluripotency of human embryonic stem cell without b-FGF in a density dependent manner.

    Ma, Xiaorong; Li, Huanqi; Xin, Shujia; Ma, Yueting; Ouyang, Tianxiang


    Human embryonic stem cells (hESCs) are pluripotent cells which can give rise to almost all adult cell lineages. Culture system of hESCs is complex, requiring exogenous b-FGF and feeder cell layer. Human mesenchymal stem cells (MSCs) not only synthesize soluble cytokines or factors such as b-FGF, but also provide other mechanism which might play positive role on sustaining hESCs propagation and pluripotency. Human amniotic fluid stem (AFS) cells, which share characteristics of both embryonic and adult stem cells, have been regarded as promising cells for regenerative medicine. Taking advantage by AFS cells, we studied the ability of AFS cells in supporting undifferentiated propagation and pluripotency of Chinese population derived X-01 hESCs. Human AF-type amniotic fluid stem cells (hAF-AFSCs) transcribed genes including Activin A, TGF-β1, Noggin and b-FGF, which involved in maintaining pluripotency and self-renewal of hESCs. Compared to mouse embryonic fibroblasts (MEFs), hAF-AFSCs secreted higher concentration of b-FGF which was important in hESCs culture (P FGF supplementation, keeping undifferentiated status. While exogenous b-FGF was obviated, propagation of hESCs with undifferentiated status was dependent on density of hAF-AFSC feeder layer. Lower density of hAF-AFSCs resulted in rapid decline in undifferentiated clone number, while higher ones hindered the growth of colonies. The most appropriate hAF-AFSCs feeder density to maintain the X-01 hESC line without exogenous b-FGF was 15-20×10(4)/well. To the best of our knowledge, this is the first study demonstrating that hAF-AFSCs could support undifferentiated propagation and pluripotency of Chinese population derived hESCs without exogenous b-FGF supplementation.


    肖成祖; 黄子才; 张正光; 叶建新; 高丽华; 郭智霞; 程度胜; 周鹤山; 孔惟惟


    CD-1,a genetically-engineered CHO cell line,was cultivated with a Biosilon microcarrier culture system.We successfully cultivated CD-1 cells to a very high density(over 1 ×107 cells/ml).Prourokinase was stably secreted at about 180IU/106 cells/24h.Experiments showed that CD-1 cells growing on Biosilon microcarriers were able to spontaneously release from the microcarriers,then reattach and proliferate on fresh microcarries.This makes it very easy to scale up production.The microcarries could be reused several times without affecting adhesion ,proliferation and prourokinase secretion.With CM-PECC membrane radial flow chromatography and MPG chromatography,the prouroknase in conditioned medium could be purfied to a specific activity of 1×105IU/mg of protein.The purification factor was about 600 fold,and approxiamately 90% of the biological activity was recovered.

  19. A Breast Cell Atlas: Organelle analysis of the MDA-MB-231 cell line by density-gradient fractionation using isotopic marking and label-free analysis

    Marianne Sandin


    Full Text Available Protein translocation between organelles in the cell is an important process that regulates many cellular functions. However, organelles can rarely be isolated to purity so several methods have been developed to analyse the fractions obtained by density gradient centrifugation. We present an analysis of the distribution of proteins amongst organelles in the human breast cell line, MDA-MB-231 using two approaches: an isotopic labelling and a label-free approach.

  20. Comparative density functional theory and density functional tight binding study of arginine and arginine-rich cell penetrating peptide TAT adsorption on anatase TiO2.

    Li, Wenxuan; Kotsis, Konstantinos; Manzhos, Sergei


    We present a comparative density functional theory (DFT) and density functional tight binding (DFTB) study of geometries and electronic structures of arginine (Arg), arginine adsorbed on the anatase (101) surface of titania in several adsorption configurations, and of an arginine-rich cell penetrating peptide TAT and its adsorption on the surface of TiO2. Two DFTB parameterizations are considered, tiorg-0-1/mio-1-1 and matsci-0-3. While there is good agreement in the structures and relative energies of Arg and peptide conformers between DFT and DFTB, both adsorption geometries and energies are noticeably different for Arg adsorbed on TiO2. The tiorg-0-1/mio-1-1 parameterization performs better than matsci-0-3. We relate this difference to the difference in electronic structures resulting from the two methods (DFT and DFTB) and specifically to the band alignment between the molecule and the oxide. We show that the band alignment of TAT and TiO2 modeled with DFTB is qualitatively correct but that with DFT using the PBE functional is not. This is specific to the modeling of large molecules where the HOMO is close to the conduction band of the oxide. We therefore report a case where the approximate DFT-based method - DFTB (with which the correct band structure can be effectively obtained) - performs better than the DFT itself with a functional approximation feasible for the modeling of large bio-inorganic interfaces, i.e. GGA (as opposed to hybrid functionals which are impractical at such a scale). Our results highlight the utility of the DFTB method for the modeling of bioinorganic interfaces not only from the CPU cost perspective but also from the accuracy point of view.

  1. Fiber diameter and seeding density influence chondrogenic differentiation of mesenchymal stem cells seeded on electrospun poly(ε-caprolactone) scaffolds.

    Bean, Allison C; Tuan, Rocky S


    Chondrogenic differentiation of mesenchymal stem cells is strongly influenced by the surrounding chemical and structural milieu. Since the majority of the native cartilage extracellular matrix is composed of nanofibrous collagen fibrils, much of recent cartilage tissue engineering research has focused on developing and utilizing scaffolds with similar nanoscale architecture. However, current literature lacks consensus regarding the ideal fiber diameter, with differences in culture conditions making it difficult to compare between studies. Here, we aimed to develop a more thorough understanding of how cell-cell and cell-biomaterial interactions drive in vitro chondrogenic differentiation of bone-marrow-derived mesenchymal stem cells (MSCs). Electrospun poly(ε-caprolactone) microfibers (4.3  ±  0.8 µm diameter, 90 μm(2) pore size) and nanofibers (440  ±  20 nm diameter, 1.2 μm(2) pore size) were seeded with MSCs at initial densities ranging from 1  ×  10(5) to 4  ×  10(6) cells cm(-3)-scaffold and cultured under transforming growth factor-β (TGF-β) induced chondrogenic conditions for 3 or 6 weeks. Chondrogenic gene expression, cellular proliferation, as well as sulfated glycosaminoglycan and collagen production were enhanced on microfiber in comparison to nanofiber scaffolds, with high initial seeding densities being required for significant chondrogenic differentiation and extracellular matrix deposition. Both cell-cell and cell-material interactions appear to play important roles in chondrogenic differentiation of MSCs in vitro and consideration of several variables simultaneously is essential for understanding cell behavior in order to develop an optimal tissue engineering strategy.

  2. ‘Living’ PEGylation on gold nanoparticles to optimize cancer cell uptake by controlling targeting ligand and charge densities

    Chen, Hongwei; Paholak, Hayley; Ito, Masayuki; Sansanaphongpricha, Kanokwan; Qian, Wei; Che, Yong; Sun, Duxin


    We report and demonstrate biomedical applications of a new technique—‘living’ PEGylation—that allows control of the density and composition of heterobifunctional PEG (HS-PEG-R; thiol-terminated poly(ethylene glycol)) on gold nanoparticles (AuNPs). We first establish ‘living’ PEGylation by incubating HS-PEG5000-COOH with AuNPs (˜20 nm) at increasing molar ratios from zero to 2000. This causes the hydrodynamic layer thickness to differentially increase up to 26 nm. The controlled, gradual increase in PEG-COOH density is revealed after centrifugation, based on the ability to re-suspend the pellet and increase the AuNP absorption. Using a fluorescamine-based assay we quantify differential HS-PEG5000-NH2 binding to AuNPs, revealing that it is highly efficient until AuNP saturation is reached. Furthermore, the zeta potential incrementally changes from -44.9 to +52.2 mV and becomes constant upon saturation. Using ‘living’ PEGylation we prepare AuNPs with different ratios of HS-PEG-RGD (RGD: Arg-Gly-Asp) and incubate them with U-87 MG (malignant glioblastoma) and non-target cells, demonstrating that targeting ligand density is critical to maximizing the efficiency of targeting of AuNPs to cancer cells. We also sequentially control the HS-PEG-R density to develop multifunctional nanoparticles, conjugating positively charged HS-PEG-NH2 at increasing ratios to AuNPs containing negatively charged HS-PEG-COOH to reduce uptake by macrophage cells. This ability to minimize non-specific binding/uptake by healthy cells could further improve targeted nanoparticle efficacy.

  3. Low Temperature, High Energy Density Micro Thin Film Solid Oxide Fuel Cell Project

    National Aeronautics and Space Administration — A new type of solid oxide fuel cell based on thin film technology and ultra-thin electrolyte is being proposed to develop to realize major reductions in fuel cell...

  4. Production of savinase and population viability of Bacillus clausii during high-cell-density fed-batch cultivations

    Christiansen, Torben; Michaelsen, S.; Wumpelmann, M.


    feed profiles applied and, in addition, there was a time-dependent decrease in specific productivity. The specific glucose uptake rate increased with time for constant specific growth rate indicating that the maintenance requirements increased with time, possibly due to a decreasing K+ concentration......The growth and product formation of a Savinase-producing Bacillus clausii were investigated in high-cell-density fed-batch cultivations with both linear and exponential feed profiles. The highest specific productivity of Savinase was observed shortly after the end of the initial batch phase for all....... The physiological state of the cells was monitored during the cultivations using a flow cytometry assay based on the permeability of the cell membrane to propidium iodide. In the latter parts of the fed-batch cultures with a linear feed profile, a large portion of the cell population was found to have a permeable...

  5. High energy efficiency and high power density proton exchange membrane fuel cells: Electrode kinetics and mass transport

    Srinivasan, Supramaniam; Velev, Omourtag A.; Parthasathy, Arvind; Manko, David J.; Appleby, A. John


    The development of proton exchange membrane (PEM) fuel cell power plants with high energy efficiencies and high power densities is gaining momentum because of the vital need of such high levels of performance for extraterrestrial (space, underwater) and terrestrial (power source for electric vehicles) applications. Since 1987, considerable progress has been made in achieving energy efficiencies of about 60 percent at a current density of 200 mA/sq cm and high power densities (greater than 1 W/sq cm) in PEM fuel cells with high (4 mg/sq cm) or low (0.4 mg/sq cm) platinum loadings in electrodes. The following areas are discussed: (1) methods to obtain these high levels of performance with low Pt loading electrodes - by proton conductor impregnation into electrodes, localization of Pt near front surface; (2) a novel microelectrode technique which yields electrode kinetic parameters for oxygen reduction and mass transport parameters; (3) demonstration of lack of water transport from anode to cathode; (4) modeling analysis of PEM fuel cell for comparison with experimental results and predicting further improvements in performance; and (5) recommendations of needed research and development for achieving the above goals.

  6. Integrated economic and experimental framework for screening of primary recovery technologies for high cell density CHO cultures.

    Popova, Daria; Stonier, Adam; Pain, David; Titchener-Hooker, Nigel J; Farid, Suzanne S


    Increases in mammalian cell culture titres and densities have placed significant demands on primary recovery operation performance. This article presents a methodology which aims to screen rapidly and evaluate primary recovery technologies for their scope for technically feasible and cost-effective operation in the context of high cell density mammalian cell cultures. It was applied to assess the performance of current (centrifugation and depth filtration options) and alternative (tangential flow filtration (TFF)) primary recovery strategies. Cell culture test materials (CCTM) were generated to simulate the most demanding cell culture conditions selected as a screening challenge for the technologies. The performance of these technology options was assessed using lab scale and ultra scale-down (USD) mimics requiring 25-110mL volumes for centrifugation and depth filtration and TFF screening experiments respectively. A centrifugation and depth filtration combination as well as both of the alternative technologies met the performance selection criteria. A detailed process economics evaluation was carried out at three scales of manufacturing (2,000L, 10,000L, 20,000L), where alternative primary recovery options were shown to potentially provide a more cost-effective primary recovery process in the future. This assessment process and the study results can aid technology selection to identify the most effective option for a specific scenario.

  7. Mechanical Stimulation in Preventing Bone Density Loss in Patients Undergoing Donor Stem Cell Transplant


    Accelerated Phase Chronic Myelogenous Leukemia; Adult Acute Lymphoblastic Leukemia in Remission; Adult Acute Myeloid Leukemia in Remission; Adult Acute Myeloid Leukemia With 11q23 (MLL) Abnormalities; Adult Acute Myeloid Leukemia With Del(5q); Adult Acute Myeloid Leukemia With Inv(16)(p13;q22); Adult Acute Myeloid Leukemia With t(15;17)(q22;q12); Adult Acute Myeloid Leukemia With t(16;16)(p13;q22); Adult Acute Myeloid Leukemia With t(8;21)(q22;q22); Atypical Chronic Myeloid Leukemia, BCR-ABL1 Negative; Blastic Phase Chronic Myelogenous Leukemia; Chronic Eosinophilic Leukemia; Chronic Myelomonocytic Leukemia; Chronic Neutrophilic Leukemia; Chronic Phase Chronic Myelogenous Leukemia; de Novo Myelodysplastic Syndromes; Disseminated Neuroblastoma; Extranodal Marginal Zone B-cell Lymphoma of Mucosa-associated Lymphoid Tissue; Myelodysplastic/Myeloproliferative Neoplasm, Unclassifiable; Nodal Marginal Zone B-cell Lymphoma; Noncontiguous Stage II Adult Burkitt Lymphoma; Noncontiguous Stage II Adult Diffuse Large Cell Lymphoma; Noncontiguous Stage II Adult Diffuse Mixed Cell Lymphoma; Noncontiguous Stage II Adult Diffuse Small Cleaved Cell Lymphoma; Noncontiguous Stage II Adult Immunoblastic Large Cell Lymphoma; Noncontiguous Stage II Adult Lymphoblastic Lymphoma; Noncontiguous Stage II Grade 1 Follicular Lymphoma; Noncontiguous Stage II Grade 2 Follicular Lymphoma; Noncontiguous Stage II Grade 3 Follicular Lymphoma; Noncontiguous Stage II Mantle Cell Lymphoma; Noncontiguous Stage II Marginal Zone Lymphoma; Noncontiguous Stage II Small Lymphocytic Lymphoma; Plasma Cell Neoplasm; Poor Prognosis Metastatic Gestational Trophoblastic Tumor; Previously Treated Myelodysplastic Syndromes; Primary Myelofibrosis; Prolymphocytic Leukemia; Recurrent Adult Acute Lymphoblastic Leukemia; Recurrent Adult Acute Myeloid Leukemia; Recurrent Adult Burkitt Lymphoma; Recurrent Adult Diffuse Large Cell Lymphoma; Recurrent Adult Diffuse Mixed Cell Lymphoma; Recurrent Adult Diffuse Small Cleaved

  8. Forming high efficiency silicon solar cells using density-graded anti-reflection surfaces

    Yuan, Hao-Chih; Branz, Howard M.; Page, Matthew R.


    A method (50) is provided for processing a graded-density AR silicon surface (14) to provide effective surface passivation. The method (50) includes positioning a substrate or wafer (12) with a silicon surface (14) in a reaction or processing chamber (42). The silicon surface (14) has been processed (52) to be an AR surface with a density gradient or region of black silicon. The method (50) continues with heating (54) the chamber (42) to a high temperature for both doping and surface passivation. The method (50) includes forming (58), with a dopant-containing precursor in contact with the silicon surface (14) of the substrate (12), an emitter junction (16) proximate to the silicon surface (14) by doping the substrate (12). The method (50) further includes, while the chamber is maintained at the high or raised temperature, forming (62) a passivation layer (19) on the graded-density silicon anti-reflection surface (14).

  9. Diabetes Mellitus Is Associated With Reduced High-Density Lipoprotein Sphingosine-1-Phosphate Content and Impaired High-Density Lipoprotein Cardiac Cell Protection.

    Brinck, Jonas W; Thomas, Aurélien; Lauer, Estelle; Jornayvaz, François R; Brulhart-Meynet, Marie-Claude; Prost, Jean-Christophe; Pataky, Zoltan; Löfgren, Patrik; Hoffstedt, Johan; Eriksson, Mats; Pramfalk, Camilla; Morel, Sandrine; Kwak, Brenda R; van Eck, Miranda; James, Richard W; Frias, Miguel A


    The dyslipidemia of type 2 diabetes mellitus has multiple etiologies and impairs lipoprotein functionality, thereby increasing risk for cardiovascular disease. High-density lipoproteins (HDLs) have several beneficial effects, notably protecting the heart from myocardial ischemia. We hypothesized that glycation of HDL could compromise this cardioprotective effect. We used in vitro (cardiomyocytes) and ex vivo (whole heart) models subjected to oxidative stress together with HDL isolated from diabetic patients and nondiabetic HDL glycated in vitro (methylglyoxal). Diabetic and in vitro glycated HDL were less effective (Pdiabetic patients (Pdiabetic HDL were inversely correlated with hemoglobin A1c (Pdiabetic HDL were significantly, positively correlated (both diabetic HDL increased its S1P content and restored its cardioprotective function. Our data demonstrate that glycation can reduce the S1P content of HDL, leading to increased cardiomyocyte cell death because of less effective activation of intracellular survival pathways. It has important implications for the functionality of HDL in diabetes mellitus because HDL-S1P has several beneficial effects on the vasculature. © 2016 American Heart Association, Inc.

  10. Surface temperature evolution and the location of maximum and average surface temperature of a lithium-ion pouch cell under variable load profiles

    Goutam, Shovon; Timmermans, Jean-Marc; Omar, Noshin;


    , manganese and cobalt (NMC) based and the anode is graphite based. In order to measure the surface temperature, thermal infrared (IR) camera and contact thermocouples were used. A fairly uniform temperature distribution was observed over the cell surface in case of continuous charge and discharge up to 100A...

  11. Olmesartan Attenuates the Impairment of Endothelial Cells Induced by Oxidized Low Density Lipoprotein through Downregulating Expression of LOX-1

    Ruolong Zheng


    Full Text Available Oxidized low density lipoprotein (ox-LDL and its receptor, lectin-Like ox-LDL receptor-1 (LOX-1, play important roles in the development of endothelial injuries. Olmesartan can protect endothelial cells from the impairment caused by various pathological stimulations. In the present study we investigated whether olmesartan decreased the impairment of endothelial cells induced by ox-LDL by exerting its effects on LOX-1 both in vitro and in vivo. Incubation of cultured endothelial cells of neonatal rats with ox-LDL for 24 h or infusion of ox-LDL in mice for 3 weeks led to the remarkable impairment of endothelial cells, including increased lactate dehydrogenase synthesis, phosphorylation of p38 mitogen-activated protein kinases (p38 MAPK and expression of apoptotic genes such as B-cell leukemia/lymphoma 2 (Bcl-2-associated X protein (Bax and caspase-3. Simultaneously, the cell vitality and expression of Bcl-2 gene were greatly reduced. All these effects, however, were significantly suppressed by the treatment with olmesartan. Furthermore, ox-LDL promoted up-regulation of LOX-1 expression either in cultured endothelial cells or in the aortas of mice, which was reversed with the administration of olmesartan. Our data indicated that olmesartan may attenuate the impairment of endothelial cell via down-regulation of the increased LOX-1 expression induced by ox-LDL.

  12. Olmesartan Attenuates the Impairment of Endothelial Cells Induced by Oxidized Low Density Lipoprotein through Downregulating Expression of LOX-1

    Zhang, Hua; Ma, Genshan; Yao, Yuyu; Qian, Huidong; Li, Weizhang; Chen, Xinjun; Jiang, Wenlong; Zheng, Ruolong


    Oxidized low density lipoprotein (ox-LDL) and its receptor, lectin-Like ox-LDL receptor-1 (LOX-1), play important roles in the development of endothelial injuries. Olmesartan can protect endothelial cells from the impairment caused by various pathological stimulations. In the present study we investigated whether olmesartan decreased the impairment of endothelial cells induced by ox-LDL by exerting its effects on LOX-1 both in vitro and in vivo. Incubation of cultured endothelial cells of neonatal rats with ox-LDL for 24 h or infusion of ox-LDL in mice for 3 weeks led to the remarkable impairment of endothelial cells, including increased lactate dehydrogenase synthesis, phosphorylation of p38 mitogen-activated protein kinases (p38 MAPK) and expression of apoptotic genes such as B-cell leukemia/lymphoma 2 (Bcl-2)-associated X protein (Bax) and caspase-3. Simultaneously, the cell vitality and expression of Bcl-2 gene were greatly reduced. All these effects, however, were significantly suppressed by the treatment with olmesartan. Furthermore, ox-LDL promoted up-regulation of LOX-1 expression either in cultured endothelial cells or in the aortas of mice, which was reversed with the administration of olmesartan. Our data indicated that olmesartan may attenuate the impairment of endothelial cell via down-regulation of the increased LOX-1 expression induced by ox-LDL. PMID:22408405

  13. Reactor-Scale Cultivation of the Hyperthermophilic Methanarchaeon Methanococcus jannaschii to High Cell Densities

    Mukhopadhyay, Biswarup; Johnson, Eric F.; Wolfe, Ralph S.


    For the hyperthermophilic and barophilic methanarchaeon Methanococcus jannaschii, we have developed a medium and protocols for reactor-scale cultivation that improved the final cell yield per liter from ∼0.5 to ∼7.5 g of packed wet cells (∼1.8 g dry cell mass) under autotrophic growth conditions and to ∼8.5 g of packed wet cells (∼2 g dry cell mass) with yeast extract (2 g liter−1) and tryptone (2 g liter−1) as medium supplements. For growth in a sealed bottle it was necessary to add Se to th...

  14. Transcriptome and proteome analysis of antibody-producing mouse myeloma NS0 cells cultivated at different cell densities in perfusion culture.

    Krampe, Britta; Swiderek, Halina; Al-Rubeai, Mohamed


    A combined gene and protein expression profiling was performed to gain a deeper insight into the intracellular response of the antibody-producing GS-NS0 cell line in continuous perfusion culture. Growth rate, production rate, metabolic activity and viability declined with increasing cell density, dilution rate and time. Transcriptome and proteome analyses of cells at three different densities revealed 53 genes and 47 proteins as having significantly altered expression levels at HCD (high cell density). The results showed an increased up-regulation of genes/proteins involved in cellular energy production with increasing cell density. Furthermore, the intensified process triggered a cellular response to external stress stimuli, revealed by an overexpression of the genes/proteins implicated in cell-cycle arrest [e.g. Rb1 (retinoblastoma 1 gene) and Cdkn1b (cyclin-dependent kinase inhibitor 1B gene)] and in the induction of pro-apoptotic genes/proteins [e.g. Tnfrsf (tumour necrosis factor receptor superfamily gene), Nfkappa bia (gene coding for nuclear factor-kappaB inhibitor), HSP60 (heat-shock protein of molecular mass 60 kDa) and heterogeneous nuclear ribonucleoprotein K]. Interestingly, we observed a down-regulation of the transcription factor interferon regulatory factor 4 involved in the unfolded-protein-response process and protein disulfide-isomerase family members responsible for protein folding and assembly. Additionally, subunits of proteasome complex were highly expressed at HCD. Microarray, real-time quantitative reverse-transcription PCR and Western-blot analyses demonstrated a consistent trend of decrease in IgG heavy-chain level with increasing cell density. HSP60, which inhibits apoptosis by complexing with pro-apoptotic proteins such as Bax and Bak, was repressed at HCD. Overall, the data suggested that the balance among several factors involved in energy metabolism might be essential for fine-tuning the cell choice between survival and apoptosis

  15. Effect of coating density on oxidation resistance and Cr vaporization from solid oxide fuel cell interconnects

    Talic, Belma; Falk-Windisch, Hannes; Venkatachalam, Vinothini


    •Protective action of dense and porous spinel coatings on Crofer 22 APU was compared. •Reduction and re-oxidation produces denser coatings than heat treating in air only. •Coating density has minor influence on oxidation resistance at 800 °C in air. •Dense coating resulted in three times lower Cr...

  16. A Study of the Conditions of Maximum Filtration Efficiency for a HGMF-Axial Magnetic Filter Cell With Bounded Flow Field

    Badescu, V.; Murariu, V.; Rotariu, O; Rezlescu, N.


    The theory of magnetic particles′ capture on a HGMF-axial magnetic filter cell with bounded flow field is presented. The equations of particle motion for both potential and laminar flow are obtained. By analytical solving of these equations, the trajectories of particles are established. The flow velocity of the fluid suspension for the case of potential flow is set equal with the velocity averaged across the tube section for the laminar flow. Thus, it is possible to make a comparison between...

  17. Metastatic spread in patients with non-small cell lung cancer is associated with a reduced density of tumor-infiltrating T cells.

    Müller, Philipp; Rothschild, Sacha I; Arnold, Walter; Hirschmann, Petra; Horvath, Lukas; Bubendorf, Lukas; Savic, Spasenija; Zippelius, Alfred


    Tumor-infiltrating lymphocytes play an important role in cell-mediated immune destruction of cancer cells and tumor growth control. We investigated the heterogeneity of immune cell infiltrates between primary non-small cell lung carcinomas (NSCLC) and corresponding metastases. Formalin-fixed, paraffin-embedded primary tumors and corresponding metastases from 34 NSCLC patients were analyzed by immunohistochemistry for CD4, CD8, CD11c, CD68, CD163 and PD-L1. The percentage of positively stained cells within the stroma and tumor cell clusters was recorded and compared between primary tumors and metastases. We found significantly fewer CD4(+) and CD8(+) T cells within tumor cell clusters as compared with the stromal compartment, both in primary tumors and corresponding metastases. CD8(+) T cell counts were significantly lower in metastatic lesions than in the corresponding primary tumors, both in the stroma and the tumor cell islets. Of note, the CD8/CD4 ratio was significantly reduced in metastatic lesions compared with the corresponding primary tumors in tumor cell islets, but not in the stroma. We noted significantly fewer CD11c(+) cells and CD68(+) as well as CD163(+) macrophages in tumor cell islets compared with the tumor stroma, but no difference between primary and metastatic lesions. Furthermore, the CD8/CD68 ratio was higher in primary tumors than in the corresponding metastases. We demonstrate a differential pattern of immune cell infiltration in matched primary and metastatic NSCLC lesions, with a significantly lower density of CD8(+) T cells in metastatic lesions compared with the primary tumors. The lower CD8/CD4 and CD8/CD68 ratios observed in metastases indicate a rather tolerogenic and tumor-promoting microenvironment at the metastatic site.

  18. Cell density-correlated induction of pyruvate decarboxylase under aerobic conditions in the yeast Pichia stipitis.

    Mergler, M; Klinner, U


    During the aerobic batch cultivation of P. stipitis CBS 5776 with glucose, pyruvate decarboxylase was activated in a cell number-correlated manner. Activation started when a cell number between 7 x 10(7) and x 10(8) cells ml(-1) was reached and the enzyme activity increased during further cultivation. This induction might have been triggered either by an unknown quorum sensing system or by a shortage of cytoplasmic acetyl-CoA.

  19. Apoptosis induced by low-level laser in polymorphonuclear cells of acute joint inflammation: comparative analysis of two energy densities.

    Dos Anjos, Lúcia Mara Januário; da Fonseca, Adenilson de Souza; Gameiro, Jacy; de Paoli, Flávia


    Anti-inflammatory property of low-level laser therapy (LLLT) has been widely described in literature, although action mechanisms are not always clarified. Thus, this study aimed to evaluate apoptosis mechanisms in the LLLT anti-inflammatory effects on the arthritis experimental model in vivo at two different energy densities (3 and 30 Jcm(-2)). Arthritis was induced in mice by zymosan solution, animals were distributed into five groups, and morphological analysis, immunocytochemistry and gene expressions for apoptotic proteins were performed. Data showed an anti-inflammatory effect, DNA fragmentation in polymorphonuclear (PMN) cells and alteration in gene expression of proteins related to apoptosis pathways after LLLT. p53 gene expression increased at both energy densities, Bcl2 gene expression increased at 3 Jcm(-2), and Bcl2 tissue expression decreased at 30 Jcm(-2). In addition, apoptosis was restricted to PMN cells. Results suggest that apoptosis in PMN cells comprise part of LLLT anti-inflammatory mechanisms by disbalance promotion between expression of pro-apoptotic (Bax and p53) and anti-apoptotic (Bcl-2) proteins, with pro-apoptotic gene expression selectively in PMN cells.

  20. Increased density of DISC1-immunoreactive oligodendroglial cells in fronto-parietal white matter of patients with paranoid schizophrenia.

    Bernstein, Hans-Gert; Jauch, Esther; Dobrowolny, Henrik; Mawrin, Christian; Steiner, Johann; Bogerts, Bernhard


    Profound white matter abnormalities have repeatedly been described in schizophrenia, which involve the altered expression of numerous oligodendrocyte-associated genes. Transcripts of the disrupted-in-schizophrenia 1 (DISC1) gene, a key susceptibility factor in schizophrenia, have recently been shown to be expressed by oligodendroglial cells and to negatively regulate oligodendrocyte differentiation and maturation. To learn more about the putative role(s) of oligodendroglia-associated DISC1 in schizophrenia, we analyzed the density of DISC1-immunoreactive oligodendrocytes in the fronto-parietal white matter in postmortem brains of patients with schizophrenia. Compared with controls (N = 12) and cases with undifferentiated/residual schizophrenia (N = 6), there was a significantly increased density of DISC1-expressing glial cells in paranoid schizophrenia (N = 12), which unlikely resulted from neuroleptic treatment. Pathophysiologically, over-expression of DISC1 protein(s) in white matter oligodendrocytes might add to the reduced levels of two myelin markers, 2',3'-cyclic-nucleotide 3'-phosphodiesterase and myelin basic protein in schizophrenia. Moreover, it might significantly contribute to cell cycle abnormalities as well as to deficits in oligodendroglial cell differentiation and maturation found in schizophrenia.

  1. Online determination of viable biomass up to very high cell densities in Arxula adeninivorans fermentations using an impedance signal.

    Knabben, Ingo; Regestein, Lars; Grumbach, Carsten; Steinbusch, Sven; Kunze, Gotthard; Büchs, Jochen


    Up to now biomass has been measured online by impedance analysis only at low cell densities in yeast fermentations. As industrial fermentation processes focus, for example, on producing high target concentrations of biocatalysts or pharmaceutical proteins, it is important to investigate cell growth under high cell-density conditions. Therefore, for the first time, biomass has been measured online using impedance analysis in a 50L high-pressure stirred tank reactor. As model organism the yeast Arxula adeninivorans was cultivated in two chemically defined mineral media at a constant growth rate in fed-batch mode. To ensure aerobic culture conditions over the entire fermentation time, the fermentations were conducted at an elevated headspace overpressure of up to 9.5bar. The highest oxygen transfer rate value of 0.56molL(-1)h(-1) ever reported for yeast fermentations was measured in these investigations. Unlike previous findings, in this study a linear correlation was found between capacitance and biomass up to concentrations of 174gL(-1) dry cell weight.

  2. The effect of oxidized low-density lipoprotein combined with adriamycin on the proliferation of Eca-109 cell line

    Cui Jia


    Full Text Available Abstract Background The purpose of this study was to identify the affect on the proliferation Eca-109 cells treated with oxidized low-density lipoprotein (ox-LDL combined with adriamycin (ADM. Methods Eca-109 cell were cultured in the presence of oxLDL/ADM, and cell proliferation tested by MTT and cell apoptosis was monitored by the proportion of apoptosis and cell cycle by flow cytomester. We simultaneously evaluated the level of associated- apoptosis Bcl-2, Bax, and Caspase-3 gene mRNA and protein. Results OxLDL were cytotoxic and activate apoptosis. OxLDL combined with ADM significant enhanced the proportion rate of apoptosis on a time and dose dependency. The expressions of the inhibiting apoptosis Bcl-2 gene mRNA and protein were down regulated, whereas, the expressions of the promoting apoptosis Bax, and Caspase-3 genes mRNA and protein were up regulation. Conclusion These results suggested that oxLDL have cytotoxicity and activate apoptosis on the Eca-109 cells. OxLDL combined with ADM have a synergistic effect on the apoptosis induced Eca-109 cells. Furthermore, oxLDL may contribute to the improvement of clinical chemotherapy of cancer need to make further investigation.

  3. Cell-penetrating compounds preferentially bind glycosaminoglycans over plasma membrane lipids in a charge density- and stereochemistry-dependent manner.

    Prevette, Lisa E; Benish, Nicolas C; Schoenecker, Amber R; Braden, Kristin J


    Cell-penetrating compounds (CPCs) are often conjugated to drugs and genes to facilitate cellular uptake. We hypothesize that the electrostatic interaction between the positively charged amines of the cell-penetrating compounds and the negatively charged glycosaminoglycans (GAGs) extending from cell surfaces is the initiating step in the internalization process. The interactions of generation 5 PAMAM dendrimer, Tat peptide and 25 kDa linear PEI with four different GAGs have been studied using isothermal titration calorimetry to elucidate structure-function relationships that could lead to improved drug and gene delivery methods to a wide variety of cell types. Detailed thermodynamic analysis has determined that CPC-GAG binding constants range from 8.7×10(3) to 2.4×10(6)M(-1) and that affinity is dependent upon GAG charge density and stereochemistry and CPC molecular weight. The effect of GAG composition on affinity is likely due to hydrogen bonding between CPC amines and amides and GAG hydroxyl and amine groups. These results were compared to the association of CPCs with lipid vesicles of varying composition as model plasma membranes to finally clarify the relative importance of each cell surface component in initial cell recognition. CPC-lipid affinity increases with anionic lipid content, but GAG affinity is higher for all cell-penetrating compounds, confirming the role these heterogeneous polysaccharides play in cellular association and clustering.

  4. Regulation of Kv2.1 K+ conductance by cell surface channel density

    Fox, Philip D.; Loftus, Rob J.; Tamkun, Michael M.


    The Kv2.1 voltage-gated K+ channel is found both freely diffusing over the plasma membrane and concentrated in micron-sized clusters localized to the soma, proximal dendrites and axon initial segment of hippocampal neurons. In transfected HEK cells, Kv2.1 channels within cluster microdomains are non-conducting. Using TIRF microscopy the number of GFP-tagged Kv2.1 channels on the HEK cell surface was compared to K+ channel conductance measured by whole-cell voltage-clamp of the same cell. This...

  5. Optimization of efficiency and energy density of passive micro fuel cells and galvanic hydrogen generators

    Hahn, Robert; Krumbholz, Steffen; Reichl, Herbert


    A PEM micro fuel cell system is described which is based on self-breathing PEM micro fuel cells in the power range between 1 mW and 1W. Hydrogen is supplied with on-demand hydrogen production with help of a galvanic cell, that produces hydrogen when Zn reacts with water. The system can be used as a battery replacement for low power applications and has the potential to improve the run time of autonomous systems. The efficiency has been investigated as function of fuel cell construction and tested for several load profiles.

  6. Matrix density alters zyxin phosphorylation, which limits peripheral process formation and extension in endothelial cells invading 3D collagen matrices.

    Abbey, Colette A; Bayless, Kayla J


    This study was designed to determine the optimal conditions required for known pro-angiogenic stimuli to elicit successful endothelial sprouting responses. We used an established, quantifiable model of endothelial cell (EC) sprout initiation where ECs were tested for invasion in low (1 mg/mL) and high density (5 mg/mL) 3D collagen matrices. Sphingosine 1-phosphate (S1P) alone, or S1P combined with stromal derived factor-1α (SDF) and phorbol ester (TPA), elicited robust sprouting responses. The ability of these factors to stimulate sprouting was more effective in higher density collagen matrices. S1P stimulation resulted in a significant increase in invasion distance, and with the exception of treatment groups containing phorbol ester, invasion distance was longer in 1mg/mL compared to 5mg/mL collagen matrices. Closer examination of cell morphology revealed that increasing matrix density and supplementing with SDF and TPA enhanced the formation of multicellular structures more closely resembling capillaries. TPA enhanced the frequency and size of lumen formation and correlated with a robust increase in phosphorylation of p42/p44 Erk kinase, while S1P and SDF did not. Also, a higher number of significantly longer extended processes formed in 5mg/mL compared to 1mg/mL collagen matrices. Because collagen matrices at higher density have been reported to be stiffer, we tested for changes in the mechanosensitive protein, zyxin. Interestingly, zyxin phosphorylation levels inversely correlated with matrix density, while levels of total zyxin did not change significantly. Immunofluorescence and localization studies revealed that total zyxin was distributed evenly throughout invading structures, while phosphorylated zyxin was slightly more intense in extended peripheral processes. Silencing zyxin expression increased extended process length and number of processes, while increasing zyxin levels decreased extended process length. Altogether these data indicate that ECs

  7. Collision rates for rare cell capture in periodic obstacle arrays strongly depend on density of cell suspension.

    Cimrák, I


    Recently, computational modelling has been successfully used for determination of collision rates for rare cell capture in periodic obstacle arrays. The models were based on particle advection simulations where the cells were advected according to velocity field computed from two dimensional Navier-Stokes equations. This approach may be used under the assumption of very dilute cell suspensions where no mutual cell collisions occur. We use the object-in-fluid framework to demonstrate that even with low cell-to-fluid ratio, the optimal geometry of the obstacle array significantly changes. We show computational simulations for ratios of 3.5, 6.9 and 10.4% determining the optimal geometry of the periodic obstacle arrays. It was already previously demonstrated that cells in periodic obstacle arrays follow trajectories in two modes: the colliding mode and the zig-zag mode. The colliding mode maximizes the cell-obstacle collision frequency. Our simulations reveal that for dilute suspensions and for suspensions with cell-to-fluid ratio 3.5%, there is a range of column shifts for which the cells follow colliding trajectories. However we showed, that for 6.9 and 10.4%, the cells never follow colliding trajectories.

  8. Novel Circuitry Configuration with Paired-Cell Erase Operation for High-Density 90-nm Embedded Resistive Random Access Memory

    Sato, Yoshihiro; Tsunoda, Koji; Aoki, Masaki; Sugiyama, Yoshihiro


    We propose a novel circuitry configuration for high-density 90-nm embedded resistive random access memory (ReRAM). The memory cells are operated at 2 V, and a small memory cell size of 6F2 consisting of a 1.2-V standard transistor and a resistive junction (1T-1R) is designed, where F is the feature size. The unique circuitry configuration is that each pair of source-lines connects to each source-line selective gate. Therefore, erasing is done by a pair of cells in turn in the whole sector, while the reading or programming is done by a random accessing operation. We simulated the ReRAM circuit for read and write operations with SPICE. As a result, we found that 5-ns high-speed read access was obtained in the 256-word lines (WLs) × 256-bit lines (BLs) and that the SET/RESET operation was stable.

  9. Natural dye extracted from karkadah and its application in dye-sensitized solar cells: experimental and density functional theory study.

    Reda, S M; Soliman, K A


    This work presents an experimental and theoretical study of cyanidin natural dye as a sensitizer for ZnO dye-sensitized solar cells. ZnO nanoparticles were prepared using ammonia and oxalic acid as a capping agent. The calculated average size of the synthesized ZnO with different capping agents was found to be 32.1 nm. Electronic properties of cyanidin and delphinidin dye were studied using density functional theory (DFT) and time-dependent DFT with a B3LYP/6-31G(d,p) level. By comparing the theoretical results with the experimental data, the cyanidin dye can be used as a sensitizer in dye-sensitized solar cells. An efficiency of 0.006% under an AM-1.5 illumination at 100  mW/cm(2) was attained. The influence of dye adsorption time on the solar cell performance is discussed.

  10. High cell density cultures produced by internal retention: application in continuous ethanol fermentation

    Berta Carola Pérez


    Full Text Available Ethanol has provoked great interest due to its potential as an alternative fuel. Nevertheless, fermentation processes must be developed by increasing the low volumetric productivity achieved in conventional cultures (batch or continuous to make this product become economically competitive. This can be achieved by using techniques leading to high cell concentration and reducing inhibition by the end-product. One of the frequently employed methods involves cell recycling. This work thus developed a membrane reactor incorporating a filtration module with 5 u,m stainless steel tubular units inside a 3L stirred jar fermenter for investigating its application in continuous ethanol production. The effects of cell concentration and transmembrane pressure difference on permeate flux were evaluated for testing the filtration module's performance. The internal cell retention system was operated in Saccharomyces cerevisiae continuous culture derived from sucrose, once fermentation conditions had been selected (30 °C, 1.25 -1.75 vvm, pH 4.5. Filter unit permeability was maintained by applying pulses of air. More than 97% of the grown cells were retained in the fermenter, reaching 51 g/L cell concentration and 8.51 g/L.h average ethanol productivity in culture with internal cell retention; this was twice that obtained in a conventional continuous culture. Key words: Membrane reactor, Saccharomyces cerevisiae, alcoholic fermentation, cell recycling.

  11. New stopping cell capabilities : RF carpet performance at high gas density and cryogenic operation

    Ranjan, M.; Purushothaman, S.; Dickel, T.; Geissel, H.; Plass, W. R.; Schaefer, D.; Scheidenberger, C.; Van de Walle, J.; Weick, H.; Dendooven, P.


    We have developed a stopping cell to be used at the FRS and Super-FRS (Superconducting FRagment Separator) at the GSI Helmholtz Centre for Heavy-Ion Research and the Facility for Antiproton and Ion Research (FAIR), both in Darmstadt, Germany. The cell has a stopping volume with a length of 1m and a

  12. Multilevel SOT-MRAM Cell with a Novel Sensing Scheme for High-Density Memory Applications

    Zeinali, Behzad; Madsen, Jens Kargaard; Moradi, Farshad

    This paper presents a multilevel spin-orbit torque magnetic random access memory (SOT-MRAM). The conventional SOT-MRAMs enables a reliable and energy efficient write operation. However, these cells require two access transistors per cell, hence the efficiency of the SOTMRAMs can be questioned in ...

  13. Density and SUV Ratios from PET/CT in the Detection of Mediastinal Lymph Node Metastasis in Non-small Cell Lung Cancer

    Tingting SHAO


    Full Text Available Background and objective Mediastinal involvement in lung cancer is a highly significant prognostic factor for survival, and accurate staging of the mediastinum will correctly identify patients who will benefit the most from surgery. Positron emission tomography/computed tomography (PET/CT has become the standard imaging modality for the staging of patients with lung cancer. The aim of this study is to investigate 18-fluoro-2-deoxy-glucose (18F-FDG PET/CT imaging in the detection of mediastinal disease in lung cancer. Methods A total of 72 patients newly diagnosed with non-small cell lung cancer (NSCLC who underwent preoperative whole-body 18F-FDG PET/CT were retrospectively included. All patients underwent radical surgery and mediastinal lymph node dissection. Mediastinal disease was histologically confirmed in 45 of 413 lymph nodes. PET/CT doctors analyzed patients’ visual images and evaluated lymph node’s short axis, lymph node’s maximum standardized uptake value (SUVmax, node/aorta density ratio, node/aorta SUV ratio, and other parameters using the histopathological results as the reference standard. The optimal cutoff value for each ratio was determined by receiver operator characteristic curve analysis. Results Using a threshold of 0.9 for density ratio and 1.2 for SUV ratio yielded high accuracy for the detection of mediastinal disease. The lymph node’s short axis, lymph node’s SUVmax, density ratio, and SUV ratio of integrated PET/CT for the accuracy of diagnosing mediastinal lymph node was 95.2%. The diagnostic accuracy of mediastinal lymph node with conventional PET/CT was 89.8%, whereas that of PET/CT comprehensive analysis was 90.8%. Conclusion Node/aorta density ratio and SUV ratio may be complimentary to conventional visual interpretation and SUVmax measurement. The use of lymph node’s short axis, lymph node’s SUVmax, and both ratios in combination is better than either conventional PET/CT analysis or PET

  14. Comparative density of CCK- and PV-GABA cells within the cortex and hippocampus

    Paul David Whissell


    Full Text Available Cholecystokinin (CCK- and parvalbumin (PV-expressing neurons constitute the two major populations of perisomatic GABAergic neurons in the cortex and the hippocampus. As CCK- and PV-GABA neurons differ in an array of morphological, biochemical and electrophysiological features, it has been proposed that they form distinct inhibitory ensembles which differentially contribute to network oscillations and behaviour. However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale. Here, we systemically investigated the distribution of CCK- and PV-GABA cells across a wide number of discrete forebrain regions using an intersectional genetic approach. Our analysis revealed several novel trends in the distribution of these cells. While PV-GABA cells were more abundant overall, CCK-GABA cells outnumbered PV-GABA cells in several subregions of the hippocampus, medial prefrontal cortex and ventrolateral temporal cortex. Interestingly, CCK-GABA cells were relatively more abundant in secondary/association areas of the cortex (V2, S2, M2, and AudD/AudV than they were in corresponding primary areas (V1, S1, M1 and Aud1. The reverse trend was observed for PV-GABA cells. Our findings suggest that the balance between CCK- and PV-GABA cells in a given cortical region is related to the type of processing that area performs; inhibitory networks in the secondary cortex tend to favour the inclusion of CCK-GABA cells more than networks in the primary cortex. The intersectional genetic labelling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons. This technique can be applied to the investigation of neuropathologies which involve disruptions to the GABAergic system, including schizophrenia, stress, maternal immune activation and autism.

  15. Non-acid-fastness in Mycobacterium tuberculosis ΔkasB mutant correlates with the cell envelope electron density.

    Yamada, Hiroyuki; Bhatt, Apoorva; Danev, Radostin; Fujiwara, Nagatoshi; Maeda, Shinji; Mitarai, Satoshi; Chikamatsu, Kinuyo; Aono, Akio; Nitta, Koji; Jacobs, William R; Nagayama, Kuniaki


    The acid-fastness is the most important and the most specific characteristics in mycobacteria, the mechanism of which is not clear but may be attributed to the lipid rich cell wall of this bacterium. While the exact component(s) responsible for this staining method remained unidentified, a Mycobacterium tuberculosis mutant, attenuated strain that produced shorter mycolic acids with defects in trans-cyclopropanation was shown to be acid fast negative. In this study, we examined the ultrastructure of the cell envelope (CE) of the mutant strain ΔkasB (missing a beta-ketoacyl-ACP synthase involved in mycolic acid biosynthesis), the parental CDC1551 (wild type strain) and kasB complemented strain, and compared ultrastructural differences among them with conventional transmission electron microscopy (TEM) and cryo-transmission electron microscopy (CEM). Conventional TEM revealed that there were no detectable differences in the thickness of the cell envelope among three strains (wild-type: 43.35 ± 6.13 nm; ΔkasB: 45.98 ± 11.32 nm; complement: 40.71 ± 6.3 nm). However, CEM data demonstrated that the region between the inner and outer membranes of the mutant strain, which is composed mainly of cell wall anchored mycolic acids (MA), showed a significant decrease in electron density as compared to the wild type and kasB complement strain (567.1 ± 372.7 vs. 301.4 ± 262.1, or vs. 235.2 ± 174.9, p tuberculosis cell envelope, resulting in a reduced electron density of this layer as seen by CEM and loss of acid-fastness in light microscopical observation, and we propose a novel model of the cell envelope structure in tubercle bacilli.

  16. The joint statistics of mildly non-linear cosmological densities and slopes in count-in-cells

    Bernardeau, Francis; Pichon, Christophe


    In the context of count-in-cells statistics, the joint probability distribution of the density in two concentric spherical shells is predicted from first first principle for sigmas of the order of one. The agreement with simulation is found to be excellent. This statistics allows us to deduce the conditional one dimensional probability distribution function of the slope within under dense (resp. overdense) regions, or of the density for positive or negative slopes. The former conditional distribution is likely to be more robust in constraining the cosmological parameters as the underlying dynamics is less evolved in such regions. A fiducial dark energy experiment is implemented on such counts derived from Lambda-CDM simulations.

  17. The Measurement of High-Density Lipoprotein Mediated Cholesterol Efflux from Macrophage Cells by Liquid Chromatography Tandem Mass Spectrometry

    Mo Wang


    Full Text Available Background: Studies have shown a negative association between macrophage cholesterol efflux and atherosclerotic cardiovascular diseases (CVD. However, the current methods for measuring cholesterol efflux require a radioactive tracer and involve a variety of cell treatments, making the measurement of macrophage cholesterol efflux impractical for use in clinical laboratories. In this study, we developed a non-radioactive and precise LC/MS/MS method for the measurement of high-density lipoprotein (HDL mediated cholesterol efflux from J774 macrophages. Methods: J774 cells were seeded on 12-well plates at a density of 1.5×105 cells/ml in H-DMEM medium, and when the cells were approximately 80% confluent, they were incubated with H-DMEM medium containing 2% FBS, 0.5 μg/ml ACAT inhibitor Sandoz 58-035, and 20 μg/ml [3,4-13C]cholesterol for 6 h. After washing and equilibrating the cells, HDL samples were added at a final concentration of 7% and incubated for 8 h. The cells were lysed, and [3,4-13C]cholesterol and cholesterol were measured by LC/MS/MS. Cholesterol efflux was expressed as the percent decrease of cell [3,4-13C]cholesterol mass during the incubation. Results: When incubated with [3,4-13C]cholesterol enriched J774 cells, HDL mediated higher cell cholesterol efflux than influx compared to serum and isolated LDL; therefore, HDL was used as the extracellular acceptor. The results from healthy volunteers showed that the rate of cholesterol efflux was negatively correlated with weight, BMI, blood pressure, and FERHDL and positively correlated with HDL-C, HDL2-C, and apoAI levels. Conclusions: A LC/MS/MS method for the measurement of HDL mediated cholesterol efflux from macrophage cells has been established. This method is non-radioactive, precise and reliable and is potentially useful for the assessment of HDL function and cardiovascular disease risks.

  18. A cell spot microarray method for production of high density siRNA transfection microarrays

    Mpindi John-Patrick


    Full Text Available Abstract Background High-throughput RNAi screening is widely applied in biological research, but remains expensive, infrastructure-intensive and conversion of many assays to HTS applications in microplate format is not feasible. Results Here, we describe the optimization of a miniaturized cell spot microarray (CSMA method, which facilitates utilization of the transfection microarray technique for disparate RNAi analyses. To promote rapid adaptation of the method, the concept has been tested with a panel of 92 adherent cell types, including primary human cells. We demonstrate the method in the systematic screening of 492 GPCR coding genes for impact on growth and survival of cultured human prostate cancer cells. Conclusions The CSMA method facilitates reproducible preparation of highly parallel cell microarrays for large-scale gene knockdown analyses. This will be critical towards expanding the cell based functional genetic screens to include more RNAi constructs, allow combinatorial RNAi analyses, multi-parametric phenotypic readouts or comparative analysis of many different cell types.

  19. "allometry" Deterministic Approaches in Cell Size, Cell Number and Crude Fiber Content Related to the Physical Quality of Kangkong (Ipomoea reptans) Grown Under Different Plant Density Pressures

    Selamat, A.; Atiman, S. A.; Puteh, A.; Abdullah, N. A. P.; Mohamed, M. T. M.; Zulkeefli, A. A.; Othman, S.

    Kangkong, especially the upland type (Ipomoea reptans) is popularly consumed as a vegetable dish in the South East Asian countries for its quality related to Vitamins (A and C) and crude fiber contents. Higher fiber contents would prevent from the occurrence of colon cancer and diverticular disease. With young stem edible portion, its cell number and size contribute to the stem crude fiber content. The mathematical approach of allometry of cell size, number, and fiber content of stem could be used in determining the 'best' plant density pressure in producing the quality young stem to be consumed. Basically, allometry is the ratio of relative increment (growth or change) rates of two parameters, or the change rate associated to the log of measured variables relationship. Kangkog grown equal or lower than 55 plants m-2 produced bigger individual plant and good quality (physical) kangkong leafy vegetable, but with lower total yield per unit area as compared to those grown at higher densities.

  20. Impurity concentrations and surface charge densities on the heavily doped face of a silicon solar cell

    Weinberg, I.; Hsu, L. C.


    Increased solar cell efficiencies are attained by reduction of surface recombination and variation of impurity concentration profiles at the n(+) surface of silicon solar cells. Diagnostic techniques are employed to evaluate the effects of specific materials preparation methodologies on surface and near surface concentrations. It is demonstrated that the MOS C-V method, when combined with a bulk measurement technique, yields more complete concentration data than are obtainable by either method alone. Specifically, new solar cell MOS C-V measurements are combined with bulk concentrations obtained by a successive layer removal technique utilizing measurements of sheet resistivity and Hall coefficient.

  1. Optimization of efficiency and energy density of passive micro fuel cells and galvanic hydrogen generators

    Hahn, Robert; Wagner,Stefan; Krumbholz, Steffen; Reichl, Herbert


    Submitted on behalf of EDA Publishing Association (; International audience; A PEM micro fuel cell system is described which is based on self-breathing PEM micro fuel cells in the power range between 1 mW and 1W. Hydrogen is supplied with on-demand hydrogen production with help of a galvanic cell, that produces hydrogen when Zn reacts with water. The system can be used as a battery replacement for low power applications and has the potential to improv...

  2. Density functional theory investigation of opto-electronic properties of thieno[3,4-b]thiophene and benzodithiophene polymer and derivatives and their applications in solar cell.

    Khoshkholgh, Mehri Javan; Marsusi, Farah; Abolhassani, Mohammad Reza


    PTBs polymers with thieno[3,4-b]thiophene [TT] and benzodithiophene [BDT] units have particular properties, which demonstrate it as one of the best group of donor materials in organic solar cells. In the present work, density functional theory (DFT) is applied to investigate the optimized structure, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), band gap and dihedral angle of PTB7 at B3LYP/6-31G(d). Two different approaches are applied to carry out these investigations: Oligomer extrapolation technique and periodic boundary condition (PBC) method. The results obtained from PBC-DFT method are in fair agreement with experiments. Based on these reliable outcomes; the investigations continued to perform some derivatives of PTB7. In this study, sulfur is substituted by nitrogen, oxygen, silicon, phosphor or selenium atoms in pristine PTB7. Due to the shift of HOMO and LUMO levels, smaller band gaps are predicted to appear in some derivatives in comparison with PTB7. Maximum theoretical efficiencies, η, of the mentioned derivatives as well as local difference of dipole moments between the ground and excited states (Δμge) are computed. The results indicate that substitution of sulfur by nitrogen or oxygen in BDT unit, and silicon or phosphor in TT unit of pristine PTB7 leads to a higher η as well as Δμge.

  3. High Cell Density Process for Constitutive Production of a Recombinant Phytase in Thermotolerant Methylotrophic Yeast Ogataea thermomethanolica Using Table Sugar as Carbon Source.

    Charoenrat, Theppanya; Antimanon, Sompot; Kocharin, Kanokarn; Tanapongpipat, Sutipa; Roongsawang, Niran


    The yeast Ogataea thermomethanolica has recently emerged as a potential host for heterologous protein expression at elevated temperature. To evaluate the feasibility of O. thermomethanolica as heterologous host in large-scale fermentation, constitutive production of fungal phytase was investigated in fed-batch fermentation. The effect of different temperatures, substrate feeding strategies, and carbon sources on phytase production was investigated. It was found that O. thermomethanolica can grow in the temperature up to 40 °C and optimal at 34 °C. However, the maximum phytase production was observed at 30 °C and slightly decreased at 34 °C. The DOT stat control was the most efficient feeding strategy to obtain high cell density and avoid by-product formation. The table sugar can be used as an alternative substrate for phytase production in O. thermomethanolica. The highest phytase activity (134 U/mL) was obtained from table sugar at 34 °C which was 20-fold higher than batch culture (5.7 U/mL). At a higher cultivation temperature of 38 °C, table sugar can be used as a low-cost substrate for the production of phytase which was expressed with an acceptable yield (85 U/mL). Lastly, the results from this study reveal the industrial favorable benefits of employing O. thermomethanolica as a host for heterologous protein production.

  4. High-density growth arrest in Ras-transformed cells: low Cdk kinase activities in spite of absence of p27(Kip) Cdk-complexes.

    Groth, Anja; Willumsen, Berthe M


    The ras oncogene transforms immortalized, contact-inhibited non-malignant murine fibroblasts into cells that are focus forming, exhibit increased saturation density, and are malignant in suitable hosts. Here, we examined changes in cell cycle control complexes as normal and Ras-transformed cells ceased to grow exponentially, to reveal the molecular basis for Ras-dependent focus formation. As normal cells entered density-dependent arrest, cyclin D1 decreased while cyclin D2 was induced and replaced D1 in Cdk4 complexes. Concomitantly, p27(Kip1) levels rose and the inhibitor accumulated in both Cdk4 and Cdk2 complexes, as these kinases were inactivated. Ras-transformed cells failed to arrest at normal saturation density and showed no significant alterations in cell control complexes at this point. Yet, at an elevated density the Ras-transformed cells ceased to proliferate and entered a quiescent-like state with low Cdk4 and Cdk2 activity. Surprisingly, this delayed arrest was molecularly distinct from contact inhibition of normal cells, as it occurred in the absence of p27(Kip1) induction and cyclin D1 levels remained high. This demonstrates that although oncogenic Ras efficiently disabled the normal response to contact inhibition, a separate back-up mechanism enforced cell cycle arrest at higher cell density.

  5. Density-controlled ZnO/TiO2 nanocomposite photoanode for improving dye-sensitized solar cells performance

    Yao, Jimmy; Lin, Chih-Min; Yin, Stuart (.


    Dye-sensitized solar cells (DSSCs) via ZnO/TiO2 nanocomposite photoanode with density-controlled abilities are presented in this paper. This nanocomposite photoanode is composed of TiO2 nanoparticles dispersed into densitycontrolled vertically aligned ZnO-TiO2 core-shell nanorod arrays. The density-controlled ZnO-TiO2 core-shell nanorod arrays were synthesized directly onto fluorine-doped tin oxide (FTO) substrates using an innovative two-step wet chemical route. First, the density-controlled ZnO nanorod arrays were formed by applying a ZnO hydrothermal process from a TiO2 nanocrystals template. Second, the ZnO-TiO2 core-shell nanorod arrays were formed by depositing a TiO2 shell layer from a sol-gel process. The major advantages of a density-controlled ZnO/TiO2 nanocomposite photoanode include (1) providing a better diffusion path from ZnO nanorod arrays and (2) reducing the recombination loss by introducing an energy barrier layer TiO2 conformal shell coating. To validate the advantages of a density-controlled ZnO/TiO2 nanocomposite photoanode, DSSCs based on a ZnO/TiO2 nanocomposite photoanode were fabricated, in which N719 dye was used. The average dimensions of the ZnO nanorod arrays were 20 μm and 650 nm for the length and the diameter, respectively, while the designated spacing between each nanorod was around 5 μm. The performance of the solar cell was tested by using a standard AM 1.5 solar simulator from Newport Corporation. The experimental results confirmed that an open-circuit voltage, 0.93 V, was achieved, which was much higher than the conventional TiO2 nanoparticles thin film structure for the same thickness. Thus, density-controlled ZnO/TiO2 nanocomposite photoanodes could improve the performance of DSSCs by offering a better electron diffusion path.

  6. Effective absorption coefficient for graded band-gap semiconductors and the expected photocurrent density in solar cells

    Morales-Acevedo, Arturo [CINVESTAV del IPN, Electrical Engineering Department, Avenida IPN No. 2508, 07360 Mexico, D. F. (Mexico)


    A simple model for the generation of carriers by photons incident on a (linearly) decreasing band-gap material, such as has been described in recent CIGS solar cells, is developed. The model can be generalized for different cases such as increasing band-gap grading or for having a more complex band-gap profile. The model developed for direct band semiconductors such as CIGS or AlGaAs allows us to define an effective absorption coefficient, so that the ideal photocurrent density can be calculated in a similar manner as for solar cells with non-graded band-gap materials. We show that this model gives completely different results as those expected from intuitive approaches for calculating this ideal photocurrent density. We also show that grading of the band-gap of the absorbing material in solar cells makes the photocurrent less sensitive to the total band-gap change, in such a way that the design of the band-gap variation can be more flexible in order to have other advantages such as higher built-in voltage or higher back surface field in the device structure. (author)

  7. Increased atrial natriuretic factor receptor density in cultured vascular smooth muscle cells of the spontaneously hypertensive rat

    Khalil, F.; Fine, B.; Kuriyama, S.; Hatori, N.; Nakamura, A.; Nakamura, M.; Aviv, A.


    To explore the role of the atrial natriuretic factor (ANF) system in the pathophysiology of hypertension we examined the binding kinetics of synthetic ANF to cultured vascular smooth muscle cells (VSMCs) derived from the spontaneously hypertensive rat (SHR) and two normotensive controls-the Wistar Kyoto (WKY) and American Wistar (W). The number of maximal binding sites (Bmax) per cell (mean +/- SEM; X10(3) were: SHR = 278.0 +/- 33.0, WKY = 28.3 +/- 7.1 and W = 26.6 +/- 4.2. The differences between the SHR and normotensive strains were significant at p less than 0.001. The equilibrium dissociation constant (Kd; X 10(-9)M) was higher in SHR VSMCs (0.94 +/- 0.14) than in WKY (0.22 +/- 0.09; p less than 0.01) and W (0.39 +/- 0.14; p less than 0.02) cells. The plasma levels of the immunoreactive ANF were higher in SHR than the normotensive controls. We suggest that the relatively greater ANF receptor density in cultured VSMCs of the SHR represents a response to the in vitro environment which is relatively more deficient in ANF for VSMCs of the SHR as compared with the normotensive rats. Thus, the capacity of the SHR VSMC to regulate ANF receptor density appears to be independent of the blood pressure level.

  8. Antagonism of Secreted PCSK9 Increases Low Density Lipoprotein Receptor Expression in HepG2 Cells

    McNutt, Markey C.; Kwon, Hyock Joo; Chen, Chiyuan; Chen, Justin R.; Horton, Jay D.; Lagace, Thomas A.; (USMC); (UTSMC)


    PCSK9 is a secreted protein that degrades low density lipoprotein receptors (LDLRs) in liver by binding to the epidermal growth factor-like repeat A (EGF-A) domain of the LDLR. It is not known whether PCSK9 causes degradation of LDLRs within the secretory pathway or following secretion and reuptake via endocytosis. Here we show that a mutation in the LDLR EGF-A domain associated with familial hypercholesterolemia, H306Y, results in increased sensitivity to exogenous PCSK9-mediated cellular degradation because of enhanced PCSK9 binding affinity. The crystal structure of the PCSK9-EGF-A(H306Y) complex shows that Tyr-306 forms a hydrogen bond with Asp-374 in PCSK9 at neutral pH, which strengthens the interaction with PCSK9. To block secreted PCSK9 activity, LDLR (H306Y) subfragments were added to the medium of HepG2 cells stably overexpressing wild-type PCSK9 or gain-of-function PCSK9 mutants associated with hypercholesterolemia (D374Y or S127R). These subfragments blocked secreted PCSK9 binding to cell surface LDLRs and resulted in the recovery of LDLR levels to those of control cells. We conclude that PCSK9 acts primarily as a secreted factor to cause LDLR degradation. These studies support the concept that pharmacological inhibition of the PCSK9-LDLR interaction extracellularly will increase hepatic LDLR expression and lower plasma low density lipoprotein levels.

  9. High-Density Array of Well-Ordered HIV-1 Spikes on Synthetic Liposomal Nanoparticles Efficiently Activate B Cells

    Jidnyasa Ingale


    Full Text Available A major step toward an HIV-1 vaccine is an immunogen capable of inducing neutralizing antibodies. Envelope glycoprotein (Env mimetics, such as the NFL and SOSIP designs, generate native-like, well-ordered trimers and elicit tier 2 homologous neutralization (SOSIPs. We reasoned that the display of well-ordered trimers by high-density, particulate array would increase B cell activation compared to soluble trimers. Here, we present the design of liposomal nanoparticles displaying well-ordered Env spike trimers on their surface. Biophysical analysis, cryo- and negative stain electron microscopy, as well as binding analysis with a panel of broadly neutralizing antibodies confirm a high-density, well-ordered trimer particulate array. The Env-trimer-conjugated liposomes were superior to soluble trimers in activating B cells ex vivo and germinal center B cells in vivo. In addition, the trimer-conjugated liposomes elicited modest tier 2 homologous neutralizing antibodies. The trimer-conjugated liposomes represent a promising initial lead toward the development of more effective HIV vaccine immunogens.

  10. Alterations of monocarboxylate transporter densities during hypoxia in brain and breast tumour cells

    Cheng, Chang; Edin, Nina F Jeppesen; Lauritzen, Knut H


    Tumour cells are characterized by aerobic glycolysis, which provides biomass for tumour proliferation and leads to extracellular acidification through efflux of lactate via monocarboxylate transporters (MCTs). Deficient and spasm-prone tumour vasculature causes variable hypoxia, which favours...... tumour cell survival and metastases. Brain metastases frequently occur in patients with advanced breast cancer.Effective treatment strategies are therefore needed against brain metastasis from breast carcinoma....

  11. Improved solid oxide fuel cell stacks: Power density, durability and modularity. Final report

    Lund Frandsen, H.; Kiebach, W.R.; Hoeegh, J. (Technical Univ. of Denmark. Risoe National Lab. for Sustainable Energy, Roskilde (Denmark)) (and others)


    This report presents the work performed within the project PSO2009-1-10207 during the period from 01-04-2009 - 31-06-2010. The report is divided into three parts covering the three work packages: Stack components; Stacks and durability; and Large SOFC systems: modularity and scalability. The project contains 38 milestones and all milestones in the project have been either fully or partly fulfilled. Two major achievements within this project concern the robustness towards dynamic operations and implementation of cells with more active cathodes: Within this project tools to evaluate and test SOFC stacks with respect to robustness during dynamic operations has been developed. From stack tests performed under dynamic conditions it was observed that the effect on degradation and failure seemed to be very little. The thermo-mechanical models developed in this project in combination with the dynamic stack model was used in combination to understand why. The results clearly showed that the hardest stress field applied to the cells arises from the steady state operating point rather than from the dynamic conditions. This is a very promising result concerning the fact that especially small CHP units in a commercial system will experience dynamic conditions from load cycling and thermal cycling. A new type of cell with a more active cathode has been formulated and introduced into the TOFC stacks in this project. The aim was to improve the effect of the stack by 25 %. However, compared to a standard stack with the ''old'' cells, the stack effect was increased by 44% - from a cross flow stack with standard 2G cells to a cross flow stack with 2.5G cells. The new type of cells also show an excellent stability towards moisture in the cathode feed, and a stack with 2.5G cells has been tested for 12.000 hrs with a degradation rate of 30 mOMEGAcm2/1000 hr. (Author)

  12. Carrier density effect on recombination in PTB7-based solar cell.

    Moritomo, Yutaka; Yonezawa, Kouhei; Yasuda, Takeshi


    Organic solar cells (OSCs) are promising alternatives to the conventional inorganic solar cells due to their low-cost processing and compatibility with flexible substrates. The development of low band-gap polymer, e.g., poly-[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3]thiophenediyl

  13. Assessment of the manufacturability of Escherichia coli high cell density fermentations.

    Perez-Pardo, M A; Ali, S; Balasundaram, B; Mannall, G J; Baganz, F; Bracewell, D G


    The physical and biological conditions of the host cell obtained at the end of fermentation influences subsequent downstream processing unit operations. The ability to monitor these characteristics is central to the improvement of biopharmaceutical manufacture. In this study, we have used a combination of techniques such as adaptive focus acoustics (AFA) and ultra scale-down (USD) centrifugation that utilize milliliter quantities of sample to obtain an insight into the interaction between cells from the upstream process and initial downstream unit operations. This is achieved primarily through an assessment of cell strength and its impact on large-scale disc stack centrifugation performance, measuring critical attributes such as viscosity and particle size distribution. An Escherichia coli fed-batch fermentation expressing antibody fragments in the periplasm was used as a model system representative of current manufacturing challenges. The weakening of cell strength during cultivation time, detected through increased micronization and viscosity, resulted in a 2.6-fold increase in product release rates from the cell (as measured by AFA) and approximately fourfold decrease in clarification performance (as measured by USD centrifugation). The information obtained allows for informed harvest point decisions accounting for both product leakages during fermentation and potential losses during primary recovery. The clarification performance results were verified at pilot scale. The use of these technologies forms a route to the process understanding needed to tailor the host cell and upstream process to the product and downstream process, critical to the implementation of quality-by-design principles.

  14. In situ cannulation, microgrid follow-up and low-density plating provide first passage endothelial cell masscultures for in vitro lining.

    Zilla, P; Fasol, R; Dudeck, U; Siedler, S; Preiss, P; Fischlein, T; Müller-Glauser, W; Baitella, G; Sanan, D; Odell, J


    A rapid and reliable harvest and culture technique was developed to provide a sufficient number of autologous endothelial cells for the confluent in vitro lining of cardiovascular prostheses. Enzymatic endothelial cell detachment was achieved by the in situ application of collagenase to short vessel segments. This harvest technique resulted in a complete lack of contaminating smooth muscle cells in all of 124 cultures from nonhuman primates and 13 cultures from human adults. The use of a microgrid technique enabled the daily in situ quantification of available endothelial cells. To assess ideal plating densities after passage the population doubling time was continuously related to the cell density. Surprisingly, a low plating density of 1.5 X 10(3) endothelial cells/cm2 achieved 43% shorter cell cycles than the usual plating density of 1.0 X 10(4) endothelial cells/cm2. Moreover, low density plating enabled mass cultures after one single cell passage, thereby reducing the cell damaging effect of trypsin. When the growth characteristics of endothelial cells from five anatomically different vessel sites were compared, the external jugular vein--which would be easily accessible and dispensable in each patient--proved to be an excellent source for endothelial cell cultures. By applying in situ administration of collagenase, low density plating and microgrid follow-up to adult human saphenous vein endothelial cells, 14,000,000 first passage endothelial cells--sufficient for the in vitro lining of long vascular prostheses--were obtained 26.2 days after harvest. (95% confidence interval:22.3 to 32.2 days).

  15. Larval Survivorship and Settlement of Crown-of-Thorns Starfish (Acanthaster cf. solaris at Varying Algal Cell Densities

    Morgan S. Pratchett


    Full Text Available The dispersal potential of crown-of-thorns starfish (CoTS larvae is important in understanding both the initiation and spread of population outbreaks, and is fundamentally dependent upon how long larvae can persist while still retaining the capacity to settle. This study quantified variation in larval survivorship and settlement rates for CoTS maintained at three different densities of a single-celled flagellate phytoplankton, Proteomonas sulcata (1 × 103, 1 × 104, and 1 × 105 cells/mL. Based on the larval starvation hypothesis, we expected that low to moderate levels of phytoplankton prey would significantly constrain both survival and settlement. CoTS larvae were successfully maintained for up to 50 days post-fertilization, but larval survival differed significantly between treatments. Survival was greatest at intermediate food levels (1 × 104 cells/mL, and lowest at high (1 × 105 cells/mL food levels. Rates of settlement were also highest at intermediate food levels and peaked at 22 days post-fertilization. Peak settlement was delayed at low food levels, probably reflective of delayed development, but there was no evidence of accelerated development at high chlorophyll concentrations. CoTS larvae were recorded to settle 17–43 days post-fertilization, but under optimum conditions with intermediate algal cell densities, peak settlement occurred at 22 days post-fertilization. Natural fluctuations in nutrient concentrations and food availability may affect the number of CoTS that effectively settle, but seem unlikely to influence dispersal dynamics.

  16. Quantum gravity momentum representation and maximum energy

    Moffat, J. W.


    We use the idea of the symmetry between the spacetime coordinates xμ and the energy-momentum pμ in quantum theory to construct a momentum space quantum gravity geometry with a metric sμν and a curvature tensor Pλ μνρ. For a closed maximally symmetric momentum space with a constant 3-curvature, the volume of the p-space admits a cutoff with an invariant maximum momentum a. A Wheeler-DeWitt-type wave equation is obtained in the momentum space representation. The vacuum energy density and the self-energy of a charged particle are shown to be finite, and modifications of the electromagnetic radiation density and the entropy density of a system of particles occur for high frequencies.

  17. High-density growth arrest in Ras-transformed cells: low Cdk kinase activities in spite of absence of p27Kip Cdk-complexes

    Groth, Anja; Willumsen, Berthe Marie


    The ras oncogene transforms immortalized, contact-inhibited non-malignant murine fibroblasts into cells that are focus forming, exhibit increased saturation density, and are malignant in suitable hosts. Here, we examined changes in cell cycle control complexes as normal and Ras-transformed cells...

  18. Electron-Ion Dynamics with Time-Dependent Density Functional Theory: Towards Predictive Solar Cell Modeling: Final Technical Report

    Maitra, Neepa [Hunter College City University of New York, New York, NY (United States)


    This project investigates the accuracy of currently-used functionals in time-dependent density functional theory, which is today routinely used to predict and design materials and computationally model processes in solar energy conversion. The rigorously-based electron-ion dynamics method developed here sheds light on traditional methods and overcomes challenges those methods have. The fundamental research undertaken here is important for building reliable and practical methods for materials discovery. The ultimate goal is to use these tools for the computational design of new materials for solar cell devices of high efficiency.

  19. Galactoglucomannans increase cell population density and alter the protoxylem/metaxylem tracheary element ratio in xylogenic cultures of Zinnia.

    Benová-Kákosová, Anna; Digonnet, Catherine; Goubet, Florence; Ranocha, Philippe; Jauneau, Alain; Pesquet, Edouard; Barbier, Odile; Zhang, Zhinong; Capek, Peter; Dupree, Paul; Lisková, Desana; Goffner, Deborah


    Xylogenic cultures of zinnia (Zinnia elegans) provide a unique opportunity to study signaling pathways of tracheary element (TE) differentiation. In vitro TEs differentiate into either protoxylem (PX)-like TEs characterized by annular/helical secondary wall thickening or metaxylem (MX)-like TEs with reticulate/scalariform/pitted thickening. The factors that determine these different cell fates are largely unknown. We show here that supplementing zinnia cultures with exogenous galactoglucomannan oligosaccharides (GGMOs) derived from spruce (Picea abies) xylem had two major effects: an increase in cell population density and a decrease in the ratio of PX to MX TEs. In an attempt to link these two effects, the consequence of the plane of cell division on PX-MX differentiation was assessed. Although GGMOs did not affect the plane of cell division per se, they significantly increased the proportion of longitudinally divided cells differentiating into MX. To test the biological significance of these findings, we have determined the presence of mannan-containing oligosaccharides in zinnia cultures in vitro. Immunoblot assays indicated that beta-1,4-mannosyl epitopes accumulate specifically in TE-inductive media. These epitopes were homogeneously distributed within the thickened secondary walls of TEs when the primary cell wall was weakly labeled. Using polysaccharide analysis carbohydrate gel electrophoresis, glucomannans were specifically detected in cell walls of differentiating zinnia cultures. Finally, zinnia macroarrays probed with cDNAs from cells cultured in the presence or absence of GGMOs indicated that significantly more genes were down-regulated rather than up-regulated by GGMOs. This study constitutes a major step in the elucidation of signaling mechanisms of PX- and MX-specific genetic programs in zinnia.

  20. Effects of increasing carbon nanofiber density in polyurethane composites for inhibiting bladder cancer cell functions.

    Tsang, Melissa; Chun, Young Wook; Im, Yeon Min; Khang, Dongwoo; Webster, Thomas J


    Polyurethane (PU) is a versatile elastomer that is commonly used in biomedical applications. In turn, materials derived from nanotechnology, specifically carbon nanofibers (CNFs), have received increasing attention for their potential use in biomedical applications. Recent studies have shown that the dispersion of CNFs in PU significantly enhances composite nanoscale surface roughness, tensile properties, and thermal stability. Although there have been studies concerning normal primary cell functions on such nanocomposites, there have been few studies detailing cancer cell responses. Since many patients who require bladder transplants have suffered from bladder cancer, the ideal bladder prosthetic material should not only promote normal primary human urothelial cell (HUC) function, but also inhibit the return of bladder cancerous cell activity. This study examined the correlation between transitional (UMUC) and squamous (or SCaBER) urothelial carcinoma cells and HUC on PU:CNF nanocomposites of varying PU and CNF weight ratios (from pure PU to 4:1 [PU:CNF volume ratios], 2:1, 1:1, 1:2, and 1:4 composites to pure CNF). Composites were characterized for mechanical properties, wettability, surface roughness, and chemical composition by atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and goniometry. The adhesion and proliferation of UMUC and SCaBER cancer cells were assessed by MTS assays. Cellular responses were further quantified by measuring the amounts of nuclear mitotic protein 22 (NMP-22), vascular endothelial growth factor (VEGF), and tumor necrosis factor alpha. Results demonstrated that both UMUC and SCaBER cell proliferation rates decreased over time on substrates with increased CNF in PU. In addition, with the exception of VEGF from UMUC (which was the same across all materials), composites containing the most CNF activated cancer cells (UMUC and SCaBER) the least, as shown by

  1. High power density alkaline fuel cell technology for MMW space burst power

    Preston, J. Lawrence, Jr.; Trocciola, John C.; Wertheim, Ronald J.

    The use of advanced alkaline regenerative fuel cell energy storage systems to provide 10's to 100's of MWe of sprint (burst) power for 100's of seconds per orbit of SDI weapons platform was studied. Recharge power is supplied by a multimegawatt space based nuclear power system. Regenerative fuel cell energy storage systems offer the potential for significant platform mass reduction by reducing the size and mass of the nuclear power source required. This is because the reactor can be sized for the smaller average power level for the energy storage system, rather than the sprint power level. The regenerative fuel cell is a particularly attractive energy storage device because the fuel cell is essentially a static power conversion device, which results in excellent platform stability for weapon pointing and tracking. Based upon the detailed point design and conceptual layout, the alkaline regenerative fuel cell energy storage system is an attractive choice for integration with a nuclear thermionic system for providing multimegawatt burst power and multi orbit capability.

  2. High cell density and latent membrane protein 1 expression induce cleavage of the mixed lineage leukemia gene at 11q23 in nasopharyngeal carcinoma cell line

    Sim Sai-Peng


    Full Text Available Abstract Background Nasopharyngeal carcinoma (NPC is commonly found in Southern China and South East Asia. Epstein-Barr virus (EBV infection is well associated with NPC and has been implicated in its pathogenesis. Moreover, various chromosome rearrangements were reported in NPC. However, the underlying mechanism of chromosome rearrangement remains unclear. Furthermore, the relationship between EBV and chromosome rearrangement with respect to the pathogenesis of NPC has not been established. We hypothesize that during virus- or stress-induced apoptosis, chromosomes are initially cleaved at the base of the chromatin loop domain structure. Upon DNA repair, cell may survive with rearranged chromosomes. Methods In this study, cells were seeded at various densities to induce apoptosis. Genomic DNA extracted was processed for Southern hybridization. In order to investigate the role of EBV, especially the latent membrane protein 1 (LMP1, LMP1 gene was overexpressed in NPC cells and chromosome breaks were analyzed by inverse polymerase chain (IPCR reaction. Results Southern analysis revealed that high cell density resulted in cleavage of the mixed lineage leukemia (MLL gene within the breakpoint cluster region (bcr. This high cell density-induced cleavage was significantly reduced by caspase inhibitor, Z-DEVD-FMK. Similarly, IPCR analysis showed that LMP1 expression enhanced cleavage of the MLL bcr. Breakpoint analysis revealed that these breaks occurred within the matrix attachment region/scaffold attachment region (MAR/SAR. Conclusions Since MLL locates at 11q23, a common deletion site in NPC, our results suggest a possibility of stress- or virus-induced apoptosis in the initiation of chromosome rearrangements at 11q23. The breakpoint analysis results also support the role of chromatin structure in defining the site of chromosome rearrangement.

  3. Capsaicin protects endothelial cells and macrophage against oxidized low-density lipoprotein-induced injury by direct antioxidant action.

    Chen, Kuo-Shuen; Chen, Pei-Ni; Hsieh, Yih-Shou; Lin, Chin-Yin; Lee, Yi-Hsun; Chu, Shu-Chen


    Atherosclerosis is a chronic inflammatory vascular disease. It is characterized by endothelial dysfunction, lipid accumulation, leukocyte activation, and the production of inflammatory mediators and reactive oxygen species (ROS). Capsaicin, a biologically active compound of the red pepper and chili pepper, has several anti-oxidant, anti-inflammatory, anti-cancer, and hypolipidemic biological effects. However, its protective effects on foam cell formation and endothelial injury induced by oxidized low-density lipoprotein (oxLDL) remain unclear. In this study, we evaluated the anti-oxidative activity of capsaicin, and determined the mechanism by which capsaicin rescues human umbilical vein endothelial cells (HUVECs) from oxLDL-mediated dysfunction. The anti-oxidative activity of capsaicin was defined by Apo B fragmentation and conjugated diene production of the copper-mediated oxidation of LDL. Capsaicin repressed ROS generation, as well as subsequent mitochondrial membrane potential collapse, cytochrome c expression, chromosome condensation, and caspase-3 activation induced by oxLDL in HUVECs. Capsaicin also protected foam cell formation in macrophage RAW 264.7 cells. Our results suggest that capsaicin may prevent oxLDL-induced cellular dysfunction and protect RAW 264.7 cells from LDL oxidation.

  4. Variations of very low-density lipoprotein receptor subtype expression in gastrointestinal adenocarcinoma cells with various differentiations

    Tao Chen; Fan Wu; Feng-Ming Chen; Jun Tian; Shen Qu


    AIM: This study is aimed at investigating the expression and possible significances of very low-density lipoprotein receptor (VLDLR) subtypes in gastroenteric adenocarcinoma tissues and cells with various differentiations. METHODS: Thirty-one cases of gastroenteric carcinoma/ adjacent normal tissues were enrolled in the study, which were diagnosed and classified by the clinicopathological diagnosis. The expression of VLDLR subtypes was detected in gastroenteric carcinoma/adjacent normal tissues and three various differentiated human gastric adenocarcinoma cell lines (MKN28, SGC7901 and MKN45) by reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis.RE,SULTS: Two VLDLR subtypes, namely, type Ⅱ VLDLR and type Ⅰ VLDLR, were found to express changes in gastroenteric carcinoma tissues, their adjacent normal tissue, and gastric adenocarcinoma cell lines as well. Type Ⅱ VLDLR is predominantly expressed in poorly- or moderately-differentiated gastroenteric carcinoma tissues and gastric adenocarcinoma cell lines, whereas type ⅠVLDLR is mainly detected in well-differentiated intestinal carcinoma tissues and gastric adenocarcinoma cells compared with the adjacent normal tissues. CONCLUSION: The results suggested that the variations of the VLDLR subtype expression might be correlated with the progress and differentiation of gastroenteric carcinoma.

  5. High-density mammalian cell cultures in stirred-tank bioreactor without external pH control.

    Xu, Sen; Chen, Hao


    Maintaining desired pH is a necessity for optimal cell growth and protein production. It is typically achieved through a two-sided pH control loop on the bioreactor controller. Here we investigated cell culture processes with minimum or no pH control and demonstrated that high-density mammalian cell cultures could be maintained for long-term protein production without pH control. The intrinsic interactions between pCO2, lactate, and pH were leveraged to maintain culture pH. Fed-batch cultures at the same lower pH limit of 6.75 but different upper pH limits (7.05, 7.30, 7.45, 7.65) were evaluated in the 3L bioreactors and comparable results were obtained. Neither CO2 sparging nor base addition was required to control pH in the pH range of 6.75-7.65. The impact of sparger configurations (drilled hole sparger vs. frit sparger) and scales (3L vs. 200L) on CO2 accumulation and culture pH was also demonstrated. The same principle was applied in two perfusion cultures with steady state cell densities at 42.5±3.3 or 68.3±6.0×10(6)cells/mL with low cell specific perfusion rates (15±2 to 23±3pL/cell/day), achieving up to 1.9±0.1g/L/day bioreactor productivity. Culture pH level in the 3L perfusion bioreactors was steadily maintained by controlling the residual lactate and pCO2 levels without the requirement of external pH control for up to 40days with consistent productivity and product quality. Furthermore, culture pH could be potentially modulated via adjusting residual glucose levels and CO2 stripping capability in perfusion cultures. To the best of our knowledge, this is the first time a systematic study was performed to evaluate the long-term cell cultivation and protein production in stirred-tank bioreactors without external pH control.

  6. Results from transcranial Doppler examination on children and adolescents with sickle cell disease and correlation between the time-averaged maximum mean velocity and hematological characteristics: a cross-sectional analytical study

    Mary Hokazono

    Full Text Available CONTEXT AND OBJECTIVE: Transcranial Doppler (TCD detects stroke risk among children with sickle cell anemia (SCA. Our aim was to evaluate TCD findings in patients with different sickle cell disease (SCD genotypes and correlate the time-averaged maximum mean (TAMM velocity with hematological characteristics. DESIGN AND SETTING: Cross-sectional analytical study in the Pediatric Hematology sector, Universidade Federal de São Paulo. METHODS: 85 SCD patients of both sexes, aged 2-18 years, were evaluated, divided into: group I (62 patients with SCA/Sß0 thalassemia; and group II (23 patients with SC hemoglobinopathy/Sß+ thalassemia. TCD was performed and reviewed by a single investigator using Doppler ultrasonography with a 2 MHz transducer, in accordance with the Stroke Prevention Trial in Sickle Cell Anemia (STOP protocol. The hematological parameters evaluated were: hematocrit, hemoglobin, reticulocytes, leukocytes, platelets and fetal hemoglobin. Univariate analysis was performed and Pearson's coefficient was calculated for hematological parameters and TAMM velocities (P < 0.05. RESULTS: TAMM velocities were 137 ± 28 and 103 ± 19 cm/s in groups I and II, respectively, and correlated negatively with hematocrit and hemoglobin in group I. There was one abnormal result (1.6% and five conditional results (8.1% in group I. All results were normal in group II. Middle cerebral arteries were the only vessels affected. CONCLUSION: There was a low prevalence of abnormal Doppler results in patients with sickle-cell disease. Time-average maximum mean velocity was significantly different between the genotypes and correlated with hematological characteristics.

  7. Flow Cytometric Quantification of Peripheral Blood Cell β-Adrenergic Receptor Density and Urinary Endothelial Cell-Derived Microparticles in Pulmonary Arterial Hypertension.

    Jonathan A Rose

    Full Text Available Pulmonary arterial hypertension (PAH is a heterogeneous disease characterized by severe angiogenic remodeling of the pulmonary artery wall and right ventricular hypertrophy. Thus, there is an increasing need for novel biomarkers to dissect disease heterogeneity, and predict treatment response. Although β-adrenergic receptor (βAR dysfunction is well documented in left heart disease while endothelial cell-derived microparticles (Ec-MPs are established biomarkers of angiogenic remodeling, methods for easy large clinical cohort analysis of these biomarkers are currently absent. Here we describe flow cytometric methods for quantification of βAR density on circulating white blood cells (WBC and Ec-MPs in urine samples that can be used as potential biomarkers of right heart failure in PAH. Biotinylated β-blocker alprenolol was synthesized and validated as a βAR specific probe that was combined with immunophenotyping to quantify βAR density in circulating WBC subsets. Ec-MPs obtained from urine samples were stained for annexin-V and CD144, and analyzed by a micro flow cytometer. Flow cytometric detection of alprenolol showed that βAR density was decreased in most WBC subsets in PAH samples compared to healthy controls. Ec-MPs in urine was increased in PAH compared to controls. Furthermore, there was a direct correlation between Ec-MPs and Tricuspid annular plane systolic excursion (TAPSE in PAH patients. Therefore, flow cytometric quantification of peripheral blood cell βAR density and urinary Ec-MPs may be useful as potential biomarkers of right ventricular function in PAH.

  8. Mammary cell turnover and expression of lipogenic genes in response to silage induced CLA and diet energy density in lactating cows

    Nørgaard, J V; Baumgard, L H; Nielsen, T Skau


    The objective of this experiment was to investigate possible effects of silage induced differences in milk conjugated linoleic acids (CLA) and diet energy density on cell turnover and production capacity in the mammary gland. Cows were given high levels of canola fat and fed either grass or maize...... silage at either a high or a low diet energy density....

  9. Effects of flow on LOX-1 and oxidized low-density lipoprotein interactions in brain endothelial cell cultures.

    Mao, Xiaoou; Xie, Lin; Greenberg, David A


    Fluid shear stress and uptake of oxidized low-density lipoprotein (ox-LDL) into the vessel wall both contribute to atherosclerosis, but the relationship between shear stress and ox-LDL uptake is unclear. We examined the effects of flow, induced by orbital rotation of bEnd.3 brain endothelial cell cultures for 1 wk, on ox-LDL receptor (LOX-1) protein expression, ox-LDL uptake and ox-LDL toxicity. Orbitally rotated cultures showed no changes in LOX-1 protein expression, ox-LDL uptake or ox-LDL toxicity, compared to stationary cultures. Flow alone does not modify ox-LDL/LOX-1 signaling in bEnd.3 brain endothelial cells in vitro, suggesting that susceptibility of atheroprone vascular sites to lipid accumulation is not due solely to effects of altered flow on endothelium.

  10. Current density and polarization curves for radial flow field patterns applied to PEMFCs (Proton Exchange Membrane Fuel Cells)

    Cano-Andrade, S.; Hernandez-Guerrero, A.; Damian-Ascencio, C.E.; Rubio-Arana, J.C. [Department of Mechanical Engineering, Universidad de Guanajuato, Carretera Salamanca-Valle de Santiago 3.5 + 1.8 km, Comunidad de Palo Blanco, Salamanca, Gto. (Mexico); von Spakovsky, M.R. [Center for Energy Systems Research, Mechanical Engineering Department, Virginia Tech, Blacksburg, VA 24061 (United States)


    A numerical solution of the current density and velocity fields of a 3-D PEM radial configuration fuel cell is presented. The energy, momentum and electrochemical equations are solved using a computational fluid dynamics (CFD) code based on a finite volume scheme. There are three cases of principal interest for this radial model: four channels, eight channels and twelve channels placed in a symmetrical path over the flow field plate. The figures for the current-voltage curves for the three models proposed are presented, and the main factors that affect the behavior of each of the curves are discussed. Velocity contours are presented for the three different models, showing how the fuel cell behavior is affected by the velocity variations in the radial configuration. All these results are presented for the case of high relative humidity. The favorable results obtained for this unconventional geometry seems to indicate that this geometry could replace the conventional commercial geometries currently in use. (author)

  11. Durability of the Solid Oxide Cells for Co-Electrolysis of Steam and Carbon Dioxide under High Current Densities

    Tao, Youkun

    Production of hydrogen and syngas (CO + H2) using solid oxide electrolysis cells (SOECs) has become increasingly attractive due to high oil price, the capability for conversion and storage of intermittent energy from renewable sources and the general interest in hydrogen energy and carbon......-neutral energy sources. Long-term stability of SOECs for high fuel productivity is crucial for the application of this technology. In this work, a series of galvanostatic durability tests were performed at high current densities (|i| = 1.5 or 2.0 A/cm2), 850 oC for up to about 700 hours for co-electrolysis...... occurred during co-electrolysis of steam and CO2 at |i| ≥ 2.0 A/cm2. Gas diffusion limitations contribute to the dramatic increase of cell voltage and a very reducing atmosphere at the interface....

  12. Influence of the gas diffusion layer on PEM fuel cell power density and cost; Einfluesse der Gasdiffusionslage auf Leistungsdichte und Kosten der PEM-Brennstoffzelle

    Joerg, Kleemann


    Cost and power density form critical key criteria for the application of polymer electrolyte fuel cells in the automotive power train. A broad commercialization of this technology requires its cost to be lowered to a competitive level. Two major levers in this direction have been emphasized in the course of this study: The application of cheaper materials along with the optimization of areal power density of the fuel cell stack to minimize material consumption. In this regard, the gas diffusion layer takes on an important role. On the one hand, the implementation of lower cost and easy processable roll-good materials offers significant cost reduction potential. With even more relevance for the cost of the fuel cell power train, it was shown that the properties of the gas diffusion layer substantially determine the maximum areal power density of the fuel cell stack. At the beginning of this study, especially the lower cost roll-good materials showed significant drawbacks under this aspect that could not be explained by existing material data. The objective of this study was hence to generate a broader understanding of the influence of the gas diffusion layer on power density and thus cost and, on this basis, to optimize power density with the lower cost roll-goods. In a first step, it was shown that mechanical behaviour and compression state of the roll-good materials in the cell differ significantly from that of the non-rollable reference material. The development of a continuum-mechanical structural model for the gas diffusion layer material and the determination of structural material properties in specialized setups allowed the quantification of differences in mechanical behaviour by means of a finite element simulation. For the roll-good materials, an extremely low compression in the region under the flowfield channels was calculated, the compression of the flowfield landings could not be sufficiently transported into the channel zone by those materials. In a

  13. Transport dynamics of a high-power-density matrix-type hydrogen-oxygen fuel cell

    Prokopius, P. R.; Hagedorn, N. H.


    Experimental transport dynamics tests were made on a space power fuel cell of current design. Various operating transients were introduced and transport-related response data were recorded with fluidic humidity sensing instruments. Also, sampled data techniques were developed for measuring the cathode-side electrolyte concentration during transient operation.

  14. Preparation method of Ni@Pt/C nanocatalyst affects the performance of direct borohydride-hydrogen peroxide fuel cell: Improved power density and increased catalytic oxidation of borohydride.

    Hosseini, Mir Ghasem; Mahmoodi, Raana


    The Ni@Pt/C electrocatalysts were synthesized using two different methods: with sodium dodecyl sulfate (SDS) and without SDS. The metal loading in synthesized nanocatalysts was 20wt% and the molar ratio of Ni: Pt was 1:1. The structural characterizations of Ni@Pt/C electrocatalysts were investigated by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM). The electrocatalytic activity of Ni@Pt/C electrocatalysts toward BH4(-) oxidation in alkaline medium was studied by means of cyclic voltammetry (CV), chronopotentiometry (CP), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). The results showed that Ni@Pt/C electrocatalyst synthesized without SDS has superior catalytic activity toward borohydride oxidation (22016.92AgPt(-1)) in comparison with a catalyst prepared in the presence of SDS (17766.15AgPt(-1)) in NaBH4 0.1M at 25°C. The Membrane Electrode Assembly (MEA) used in fuel cell set-up was fabricated with catalyst-coated membrane (CCM) technique. The effect of Ni@Pt/C catalysts prepared with two methods as anode catalyst on the performance of direct borohydride-hydrogen peroxide fuel cell was studied. The maximum power density was obtained using Ni@Pt/C catalyst synthesized without SDS at 60°C, 1M NaBH4 and 2M H2O2 (133.38mWcm(-2)). Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Comparative study of trap densities of states in CdTe /CdS solar cells

    Proskuryakov, Y. Y.; Major, J. D.; Durose, K.; Barrioz, V.; Irvine, S. J. C.; Jones, E. W.; Lamb, D.


    Density of deep and shallow states has been investigated in three different kinds of CdTe /CdS samples, two of which were grown by metal-organic chemical vapor deposition (MOCVD) and one by close-space sublimation (CSS) methods. The MOCVD samples were p doped by As and grown either with or without a ZnO buffer layer between the transparent conductor and CdS layers. Capacitance-voltage, admittance spectroscopy, and quantum efficiency measurements show pronounced effects of As doping and ZnO incorporation. It is found that A centers and vacancies of Cd, usually observed in CSS devices, are absent in the defect spectra of MOCVD samples.

  16. Oxidized low density lipoprotein increases RANKL level in human vascular cells. Involvement of oxidative stress

    Mazière, Cécile, E-mail: [Biochemistry Laboratory, South Hospital University, René Laennec Avenue, Amiens 80000 (France); Salle, Valéry [Internal Medicine, North Hospital University, Place Victor Pauchet, Amiens 80000 (France); INSERM U1088 (EA 4292), SFR CAP-Santé (FED 4231), University of Picardie – Jules Verne (France); Gomila, Cathy; Mazière, Jean-Claude [Biochemistry Laboratory, South Hospital University, René Laennec Avenue, Amiens 80000 (France)


    Highlights: •Oxidized LDL enhances RANKL level in human smooth muscle cells. •The effect of OxLDL is mediated by the transcription factor NFAT. •UVA, H{sub 2}O{sub 2} and buthionine sulfoximine also increase RANKL level. •All these effects are observed in human fibroblasts and endoth