WorldWideScience

Sample records for cell size

  1. Cell Size Regulation in Bacteria

    Science.gov (United States)

    Amir, Ariel

    2014-05-01

    Various bacteria such as the canonical gram negative Escherichia coli or the well-studied gram positive Bacillus subtilis divide symmetrically after they approximately double their volume. Their size at division is not constant, but is typically distributed over a narrow range. Here, we propose an analytically tractable model for cell size control, and calculate the cell size and interdivision time distributions, as well as the correlations between these variables. We suggest ways of extracting the model parameters from experimental data, and show that existing data for E. coli supports partial size control, and a particular explanation: a cell attempts to add a constant volume from the time of initiation of DNA replication to the next initiation event. This hypothesis accounts for the experimentally observed correlations between mother and daughter cells as well as the exponential dependence of size on growth rate.

  2. On size and growth of cells

    CERN Document Server

    Boudaoud, A

    2002-01-01

    Understanding how growth induces form is a longstanding biological question. Many studies concentrated on the shapes of plant cells, fungi or bacteria. Some others have shown the importance of the mechanical properties of bacterial walls and plant tissues in pattern formation. Here I sketch a simple physical picture of cell growth. The study is focussed on isolated cells that have walls. They are modeled as thin elastic shells containing a liquid, which pressure drives the growth as generally admitted for bacteria or plant cells. Requiring mechanical equilibrium leads to estimations of typical cell sizes, in quantitative agreement with compiled data including bacteria, cochlear outer hair, fungi, yeast, root hair and giant alga cells.

  3. Mechanisms of daughter cell-size control during cell division.

    Science.gov (United States)

    Kiyomitsu, Tomomi

    2015-05-01

    Daughter cell size is tightly regulated during cell division. In animal cells, the position of the anaphase spindle specifies the cell cleavage site to dictate the relative size of the daughter cells. Although spindle orientation is regulated by dynein-dependent cortical pulling forces exerted on astral microtubules in many cell types, it was unclear how these forces are precisely regulated to center or displace the spindle. Recently, intrinsic signals derived from chromosomes or spindle poles have been demonstrated to regulate dynein-dependent pulling forces in symmetrically dividing cells. Unexpectedly, myosin-dependent contractile forces have also been shown to control spindle position by altering the cellular boundaries during anaphase. In this review, I discuss how dynein- and myosin-dependent forces are coordinately regulated to control daughter cell size. PMID:25548067

  4. Sample Size Determination: A Comparison of Attribute, Continuous Variable, and Cell Size Methods.

    Science.gov (United States)

    Clark, Philip M.

    1984-01-01

    Describes three methods of sample size determination, each having its use in investigation of social science problems: Attribute method; Continuous Variable method; Galtung's Cell Size method. Statistical generalization, benefits of cell size method (ease of use, trivariate analysis and trichotyomized variables), and choice of method are…

  5. Cell Size Breathing and Possibilities to Introduce Cell Sleep Mode

    DEFF Research Database (Denmark)

    Micallef, Gilbert; Mogensen, Preben; Scheck, Hans-Otto

    2010-01-01

    regular upgrades in the infrastructure. While network equipment is in itself becoming more efficient, these upgrades still increase the overall energy consumption of the networks. This paper investigates the energy saving potential of exploiting cell size breathing by putting low loaded cells into sleep...... investigates the possible gains of re-optimizing antenna tilting. The results show that by allowing sleep mode, over a restricted period of 12 hours, an energy saving of 33% is possible. While this energy saving comes at no expense of the overall network performance, the gain in average user data rate is noted...

  6. Scaling of number, size, and metabolic rate of cells with body size in mammals

    OpenAIRE

    Savage, M; Allen, Andrew P.; Brown, James H.; Gillooly, James F; Herman, Alexander B.; Woodruff, William H.; West, Geoffrey B.

    2007-01-01

    The size and metabolic rate of cells affect processes from the molecular to the organismal level. We present a quantitative, theoretical framework for studying relationships among cell volume, cellular metabolic rate, body size, and whole-organism metabolic rate that helps reveal the feedback between these levels of organization. We use this framework to show that average cell volume and average cellular metabolic rate cannot both remain constant with changes in body size because of the well ...

  7. Physics of sinking and selection of plankton cell size

    Energy Technology Data Exchange (ETDEWEB)

    Sciascia, R., E-mail: r.sciascia@isac.cnr.it [Institute of Atmospheric Sciences and Climate, CNR, Corso Fiume, 4, 10133 Torino (Italy); Doctorate Program in Fluid Dynamics, Politecnico di Torino (Italy); De Monte, S. [CNRS, UMR 7625 “Ecologie et Evolution”, Paris, F-75005 (France); Université Pierre et Marie Curie-Paris 6, UMR 7625 “Ecologie et Evolution”, Paris, F-75005 (France); Institut de Biologie de l' Ecole Normale Supérieure, UMR 7625 “Ecologie et Evolution”, Paris, F-75005 (France); Provenzale, A. [Institute of Atmospheric Sciences and Climate, CNR, Corso Fiume, 4, 10133 Torino (Italy)

    2013-02-04

    Gravitational sinking in the water column is known to affect size composition of planktonic communities. One important driver toward the reduction of plankton size is the fact that larger cells tend to sink faster below the euphotic layer. In this work, we discuss the role of gravitational sinking in driving cell size selection, showing that the outcome of phytoplankton competition is determined by the dependence of sinking velocity on cell size, shape, and on the temporal variability associated with turbulence. This opens a question on whether regional modulations of the turbulence intensity could affect size distribution of planktonic communities.

  8. Cell size checkpoint control by the retinoblastoma tumor suppressor pathway.

    Directory of Open Access Journals (Sweden)

    Su-Chiung Fang

    2006-10-01

    Full Text Available Size control is essential for all proliferating cells, and is thought to be regulated by checkpoints that couple cell size to cell cycle progression. The aberrant cell-size phenotypes caused by mutations in the retinoblastoma (RB tumor suppressor pathway are consistent with a role in size checkpoint control, but indirect effects on size caused by altered cell cycle kinetics are difficult to rule out. The multiple fission cell cycle of the unicellular alga Chlamydomonas reinhardtii uncouples growth from division, allowing direct assessment of the relationship between size phenotypes and checkpoint function. Mutations in the C. reinhardtii RB homolog encoded by MAT3 cause supernumerous cell divisions and small cells, suggesting a role for MAT3 in size control. We identified suppressors of an mat3 null allele that had recessive mutations in DP1 or dominant mutations in E2F1, loci encoding homologs of a heterodimeric transcription factor that is targeted by RB-related proteins. Significantly, we determined that the dp1 and e2f1 phenotypes were caused by defects in size checkpoint control and were not due to a lengthened cell cycle. Despite their cell division defects, mat3, dp1, and e2f1 mutants showed almost no changes in periodic transcription of genes induced during S phase and mitosis, many of which are conserved targets of the RB pathway. Conversely, we found that regulation of cell size was unaffected when S phase and mitotic transcription were inhibited. Our data provide direct evidence that the RB pathway mediates cell size checkpoint control and suggest that such control is not directly coupled to the magnitude of periodic cell cycle transcription.

  9. Influence of cell size on cellular uptake of gold nanoparticles.

    Science.gov (United States)

    Wang, Xinlong; Hu, Xiaohong; Li, Jingchao; Russe, Adriana C Mulero; Kawazoe, Naoki; Yang, Yingnan; Chen, Guoping

    2016-06-24

    Nanoparticles (NPs) have shown great potential for biomedical applications because of their unique physical and structural properties. A critical aspect for their clinical applications is cellular uptake that depends on both particle properties and the cell mechanical state. Despite the numerous studies trying to disclose the influencing factors, the role of cell size on cellular uptake remains unclear. In this study, poly(vinyl alcohol) was micropatterned on tissue culture polystyrene surfaces using UV photolithography to control the cell size, and the influence of cell size on the cellular uptake of gold NPs was investigated. Cells with a large size had a high total cellular uptake, but showed a low average uptake per unit area of cells. Cells with a small size showed opposite behaviors. The results were related to both cell/NP contacting area and membrane tension. A large cell size was beneficial for a high total cellular uptake due to the large contact area with the NPs. On the other hand, the large cell size resulted in high membrane tension that required high wrapping energy for engulfing of NPs and thus reduced the uptake. The two oppositely working effects decided the cellular uptake of NPs. The results would shed light on the influence of the cellular microenvironment on cellular uptake behavior. PMID:27095054

  10. Size-independent symmetric division in extraordinarily long cells

    NARCIS (Netherlands)

    N. Pende; N. Leisch; H.R. Gruber-Vodicka; N.R. Heindl; J. Ott; T. den Blaauwen; S. Bulgheresi

    2014-01-01

    Two long-standing paradigms in biology are that cells belonging to the same population exhibit little deviation from their average size and that symmetric cell division is size limited. Here, ultrastructural, morphometric and immunocytochemical analyses reveal that two Gammaproteobacteria attached t

  11. Covariation of metabolic rates and cell size in coccolithophores

    Science.gov (United States)

    Aloisi, G.

    2015-08-01

    Coccolithophores are sensitive recorders of environmental change. The size of their coccosphere varies in the ocean along gradients of environmental conditions and provides a key for understanding the fate of this important phytoplankton group in the future ocean. But interpreting field changes in coccosphere size in terms of laboratory observations is hard, mainly because the marine signal reflects the response of multiple morphotypes to changes in a combination of environmental variables. In this paper I examine the large corpus of published laboratory experiments with coccolithophores looking for relations between environmental conditions, metabolic rates and cell size (a proxy for coccosphere size). I show that growth, photosynthesis and, to a lesser extent, calcification covary with cell size when pCO2, irradiance, temperature, nitrate, phosphate and iron conditions change. With the exception of phosphate and temperature, a change from limiting to non-limiting conditions always results in an increase in cell size. An increase in phosphate or temperature (below the optimum temperature for growth) produces the opposite effect. The magnitude of the coccosphere-size changes observed in the laboratory is comparable to that observed in the ocean. If the biological reasons behind the environment-metabolism-size link are understood, it will be possible to use coccosphere-size changes in the modern ocean and in marine sediments to investigate the fate of coccolithophores in the future ocean. This reasoning can be extended to the size of coccoliths if, as recent experiments are starting to show, coccolith size reacts to environmental change proportionally to coccosphere size. The coccolithophore database is strongly biased in favour of experiments with the coccolithophore Emiliania huxleyi (E. huxleyi; 82 % of database entries), and more experiments with other species are needed to understand whether these observations can be extended to coccolithophores in general. I

  12. Nanomaterial cytotoxicity is composition, size, and cell type dependent

    Directory of Open Access Journals (Sweden)

    Sohaebuddin Syed K

    2010-08-01

    Full Text Available Abstract Background Despite intensive research efforts, reports of cellular responses to nanomaterials are often inconsistent and even contradictory. Additionally, relationships between the responding cell type and nanomaterial properties are not well understood. Using three model cell lines representing different physiological compartments and nanomaterials of different compositions and sizes, we have systematically investigated the influence of nanomaterial properties on the degrees and pathways of cytotoxicity. In this study, we selected nanomaterials of different compositions (TiO2 and SiO2 nanoparticles, and multi-wall carbon nanotubes [MWCNTs] with differing size (MWCNTs of different diameters 50 nm; but same length 0.5-2 μm to analyze the effects of composition and size on toxicity to 3T3 fibroblasts, RAW 264.7 macrophages, and telomerase-immortalized (hT bronchiolar epithelial cells. Results Following characterization of nanomaterial properties in PBS and serum containing solutions, cells were exposed to nanomaterials of differing compositions and sizes, with cytotoxicity monitored through reduction in mitochondrial activity. In addition to cytotoxicity, the cellular response to nanomaterials was characterized by quantifying generation of reactive oxygen species, lysosomal membrane destabilization and mitochondrial permeability. The effect of these responses on cellular fate - apoptosis or necrosis - was then analyzed. Nanomaterial toxicity was variable based on exposed cell type and dependent on nanomaterial composition and size. In addition, nanomaterial exposure led to cell type dependent intracellular responses resulting in unique breakdown of cellular functions for each nanomaterial: cell combination. Conclusions Nanomaterials induce cell specific responses resulting in variable toxicity and subsequent cell fate based on the type of exposed cell. Our results indicate that the composition and size of nanomaterials as well as the

  13. Comparison of DNA loop size and super-coiled domain size in human cells

    International Nuclear Information System (INIS)

    DNA loop size and super-coiled domain size in HeLa cells were investigated by the nucleoid sedimentation technique as well as by analysis of the DNA-nuclearmatrix complex. After X-irradiation, the relaxation of super-coils was not correlated with the release of DNA from the nuclear matrix. The super-coiled domain size was much larger than the average DNA loop size. To explain the results, we propose that unwinding of super-coils in a DNA loop also causes unwinding in adjacent DNA loops in spite of existing attachment sites. Alternatively, the results may be explained by assuming that only very large DNA loops determine the sedimentation behaviour of nucleoids. (orig.)

  14. A Coarse Estimation of Cell Size Region from a Mesoscopic Stochastic Cell Cycle Model

    Institute of Scientific and Technical Information of China (English)

    YI Ming; JIA Ya; LIU Quan; ZHU Chun-Lian; YANG Li-Jian

    2007-01-01

    Based on a deterministic cell cycle model of fission yeast, the effects of the finite cell size on the cell cycle regulation in wee1- cdc25△ double mutant type are numerically studied by using of the chemical Langevin equations. It is found that at a certain region of cell size, our numerical results from the chemical Langevin equations are in good qualitative agreement with the experimental observations. The two resettings to the G2 phase from early stages of mitosis can be induced under the moderate cell size. The quantized cycle times can be observed during such a cell size region. Therefore, a coarse estimation of cell size is obtained from the mesoscopic stochastic cell cycle model.

  15. A rapid method of fruit cell isolation for cell size and shape measurements

    Directory of Open Access Journals (Sweden)

    Johnston Jason W

    2009-04-01

    Full Text Available Abstract Background Cell size is a structural component of fleshy fruit, contributing to important traits such as fruit size and texture. There are currently a number of methods for measuring cell size; most rely either on tissue sectioning or digestion of the tissue with cell wall degrading enzymes or chemicals to release single cells. Neither of these approaches is ideal for assaying large fruit numbers as both require a considerable time to prepare the tissue, with current methods of cell wall digestions taking 24 to 48 hours. Additionally, sectioning can lead to a measurement of a plane that does not represent the widest point of the cell. Results To develop a more rapid way of measuring fruit cell size we have developed a protocol that solubilises pectin in the middle lamella of the plant cell wall releasing single cells into a buffered solution. Gently boiling small fruit samples in a 0.05 M Na2CO3 solution, osmotically balanced with 0.3 M mannitol, produced good cell separation with little cellular damage in less than 30 minutes. The advantage of combining a chemical treatment with boiling is that the cells are rapidly killed. This stopped cell shape changes that could potentially occur during separation. With this method both the rounded and angular cells of the apple cultivars SciRos 'Pacific Rose' and SciFresh 'Jazz'™ were observed in the separated cells. Using this technique, an in-depth analysis was performed measuring cell size from 5 different apple cultivars. Cell size was measured using the public domain ImageJ software. For each cultivar a minimum of 1000 cells were measured and it was found that each cultivar displayed a different distribution of cell size. Cell size within cultivars was similar and there was no correlation between flesh firmness and cell size. This protocol was tested on tissue from other fleshy fruit including tomato, rock melon and kiwifruit. It was found that good cell separation was achieved with flesh

  16. Influence of texture feature size on spherical silicon solar cells

    Institute of Scientific and Technical Information of China (English)

    HAYASHI Shota; MINEMOTO Takashi; TAKAKURA Hideyuki; HAMAKAWA Yoshihiro

    2006-01-01

    The effects of surface texturing on spherical silicon solar cells were investigated. Surface texturing for spherical Si solar cells was prepared by immersing p-type spherical Si crystals in KOH solution with stirring. Two kinds of texture feature sizes (1 and 5μm pyramids) were prepared by changing stirring speed. After fabrication through our baseline processes, these cells were evaluated by solar cell performance and external quantum efficiency. The cell with 1 and 5μm pyramids shows the short circuit current density ( Jsc ) value of 31.9 and 33.2 mA·cm-2 , which is 9% and 13% relative increase compared to the cell without texturing. Furthermore, the cell with 5 μm pyramids has a higher open-circuit voltage (0.589 V) than the cell with 1 μm pyramids (0.577 V). As a result, the conversion efficiency was improved from 11.4% for the cell without texturing to 12.1% for the cell with 5 μm pyramids.

  17. Vesicle Size Regulates Nanotube Formation in the Cell

    Science.gov (United States)

    Su, Qian Peter; Du, Wanqing; Ji, Qinghua; Xue, Boxin; Jiang, Dong; Zhu, Yueyao; Lou, Jizhong; Yu, Li; Sun, Yujie

    2016-01-01

    Intracellular membrane nanotube formation and its dynamics play important roles for cargo transportation and organelle biogenesis. Regarding the regulation mechanisms, while much attention has been paid on the lipid composition and its associated protein molecules, effects of the vesicle size has not been studied in the cell. Giant unilamellar vesicles (GUVs) are often used for in vitro membrane deformation studies, but they are much larger than most intracellular vesicles and the in vitro studies also lack physiological relevance. Here, we use lysosomes and autolysosomes, whose sizes range between 100 nm and 1 μm, as model systems to study the size effects on nanotube formation both in vivo and in vitro. Single molecule observations indicate that driven by kinesin motors, small vesicles (100–200 nm) are mainly transported along the tracks while a remarkable portion of large vesicles (500–1000 nm) form nanotubes. This size effect is further confirmed by in vitro reconstitution assays on liposomes and purified lysosomes and autolysosomes. We also apply Atomic Force Microscopy (AFM) to measure the initiation force for nanotube formation. These results suggest that the size-dependence may be one of the mechanisms for cells to regulate cellular processes involving membrane-deformation, such as the timing of tubulation-mediated vesicle recycling. PMID:27052881

  18. Vesicle Size Regulates Nanotube Formation in the Cell

    OpenAIRE

    Qian Peter Su; Wanqing Du; Qinghua Ji; Boxin Xue; Dong Jiang; Yueyao Zhu; Jizhong Lou; Li Yu; Yujie Sun

    2016-01-01

    Intracellular membrane nanotube formation and its dynamics play important roles for cargo transportation and organelle biogenesis. Regarding the regulation mechanisms, while much attention has been paid on the lipid composition and its associated protein molecules, effects of the vesicle size has not been studied in the cell. Giant unilamellar vesicles (GUVs) are often used for in vitro membrane deformation studies, but they are much larger than most intracellular vesicles and the in vitro st...

  19. Stationary Size Distributions of Growing Cells with Binary and Multiple Cell Division

    Science.gov (United States)

    Rading, M. M.; Engel, T. A.; Lipowsky, R.; Valleriani, A.

    2011-10-01

    Populations of unicellular organisms that grow under constant environmental conditions are considered theoretically. The size distribution of these cells is calculated analytically, both for the usual process of binary division, in which one mother cell produces always two daughter cells, and for the more complex process of multiple division, in which one mother cell can produce 2 n daughter cells with n=1,2,3,… . The latter mode of division is inspired by the unicellular algae Chlamydomonas reinhardtii. The uniform response of the whole population to different environmental conditions is encoded in the individual rates of growth and division of the cells. The analytical treatment of the problem is based on size-dependent rules for cell growth and stochastic transition processes for cell division. The comparison between binary and multiple division shows that these different division processes lead to qualitatively different results for the size distribution and the population growth rates.

  20. Scaffolds and cells for tissue regeneration: different scaffold pore sizes-different cell effects.

    Science.gov (United States)

    Bružauskaitė, Ieva; Bironaitė, Daiva; Bagdonas, Edvardas; Bernotienė, Eiva

    2016-05-01

    During the last decade biomaterial sciences and tissue engineering have become new scientific fields supplying rising demand of regenerative therapy. Tissue engineering requires consolidation of a broad knowledge of cell biology and modern biotechnology investigating biocompatibility of materials and their application for the reconstruction of damaged organs and tissues. Stem cell-based tissue regeneration started from the direct cell transplantation into damaged tissues or blood vessels. However, it is difficult to track transplanted cells and keep them in one particular place of diseased organ. Recently, new technologies such as cultivation of stem cell on the scaffolds and subsequently their implantation into injured tissue have been extensively developed. Successful tissue regeneration requires scaffolds with particular mechanical stability or biodegradability, appropriate size, surface roughness and porosity to provide a suitable microenvironment for the sufficient cell-cell interaction, cell migration, proliferation and differentiation. Further functioning of implanted cells highly depends on the scaffold pore sizes that play an essential role in nutrient and oxygen diffusion and waste removal. In addition, pore sizes strongly influence cell adhesion, cell-cell interaction and cell transmigration across the membrane depending on the various purposes of tissue regeneration. Therefore, this review will highlight contemporary tendencies in application of non-degradable scaffolds and stem cells in regenerative medicine with a particular focus on the pore sizes significantly affecting final recover of diseased organs. PMID:26091616

  1. Graphene-Based Flexible Micrometer-Sized Microbial Fuel Cell

    KAUST Repository

    Mink, Justine E.

    2013-10-23

    Microbial fuel cells harvest electrical energy produced by bacteria during the natural decomposition of organic matter. We report a micrometer-sized microbial fuel cell that is able to generate nanowatt-scale power from microliters of liquids. The sustainable design is comprised of a graphene anode, an air cathode, and a polymer-based substrate platform for flexibility. The graphene layer was grown on a nickel thin film by using chemical vapor deposition at atmospheric pressure. Our demonstration provides a low-cost option to generate useful power for lab-on-chip applications and could be promising to rapidly screen and scale up microbial fuel cells for water purification without consuming excessive power (unlike other water treatment technologies).

  2. MANOVA for Nested Designs with Unequal Cell Sizes and Unequal Cell Covariance Matrices

    Directory of Open Access Journals (Sweden)

    Li-Wen Xu

    2014-01-01

    satisfactorily for various cell sizes and parameter configurations and generally outperforms the AHT test in terms of controlling the nominal size. For the heteroscedastic cases, the PB test outperforms the AHT test in terms of power. In addition, the PB test does not lose too much power when the homogeneity assumption is actually valid.

  3. Lab-size rechargeable metal hydride-air cells

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Wei-Kang; Noreus, Dag [Department of Materials and Enviromental Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm (Sweden)

    2010-09-01

    Lab-size rechargeable metal hydride-air (MH-air) cells with a gas management device were designed in order to minimize the loss of electrolyte. An AB{sub 5}-type hydrogen storage alloy was used as anode materials of the MH-air. The thickness of the metal hydride electrodes was in the range of 3.0-3.4 mm. Porous carbon-based air electrodes with Ag{sub 2}O catalysts were used as bi-functional electrodes for oxygen reduction and generation. The electrodes were first examined in half-cells to evaluate their performance and then assembled into one MH-air cell. The results showed the good cycling stability of the rechargeable MH-air cell with a capacity of 1990 mAh. The discharge voltage was 0.69 V at 0.05-0.1 C. The charge efficiency was about 90%. The specific and volumetric energy densities were about 95Wh kg{sup -1} and 140 Wh L{sup -1}, respectively. (author)

  4. An assessment of the effects of cell size on AGNPS modeling of watershed runoff

    Science.gov (United States)

    Wu, S.-S.; Usery, E.L.; Finn, M.P.; Bosch, D.D.

    2008-01-01

    This study investigates the changes in simulated watershed runoff from the Agricultural NonPoint Source (AGNPS) pollution model as a function of model input cell size resolution for eight different cell sizes (30 m, 60 m, 120 m, 210 m, 240 m, 480 m, 960 m, and 1920 m) for the Little River Watershed (Georgia, USA). Overland cell runoff (area-weighted cell runoff), total runoff volume, clustering statistics, and hot spot patterns were examined for the different cell sizes and trends identified. Total runoff volumes decreased with increasing cell size. Using data sets of 210-m cell size or smaller in conjunction with a representative watershed boundary allows one to model the runoff volumes within 0.2 percent accuracy. The runoff clustering statistics decrease with increasing cell size; a cell size of 960 m or smaller is necessary to indicate significant high-runoff clustering. Runoff hot spot areas have a decreasing trend with increasing cell size; a cell size of 240 m or smaller is required to detect important hot spots. Conclusions regarding cell size effects on runoff estimation cannot be applied to local watershed areas due to the inconsistent changes of runoff volume with cell size; but, optimal cells sizes for clustering and hot spot analyses are applicable to local watershed areas due to the consistent trends.

  5. Cell size dynamics and viability of cells exposed to hypotonic treatment and electroporation for electrofusion optimization:

    OpenAIRE

    Hudej, Rosana; Kandušer, Maša; Miklavčič, Damijan; Trontelj, Katja; Ušaj, Marko

    2009-01-01

    Background. Various electrofusion parameters have to be adjusted to obtain theoptimal electrofusion efficiency. Based on published data, good electrofusion conditions can be achieved with the hypotonic treatment. However, the duration of the hypotonic treatment before electroporation and buffer hypoosmolarity have to be adjusted in order to cause cell swelling, to avoid regulatory volume decrease and to preserve cell viability. The aims of our study were to determine cell size dynamics and vi...

  6. Cell size dynamics and viability of cells exposed to hypotonic treatment and electroporation for electrofusion optimization

    OpenAIRE

    Trontelj, Katja; Kandušer, Maša; Miklavčič, Damijan; Hudej, Rosana; Ušaj, Marko

    2015-01-01

    Background. Various electrofusion parameters have to be adjusted to obtain theoptimal electrofusion efficiency. Based on published data, good electrofusion conditions can be achieved with the hypotonic treatment. However, the duration of the hypotonic treatment before electroporation and buffer hypoosmolarity have to be adjusted in order to cause cell swelling, to avoid regulatory volume decrease and to preserve cell viability. The aims of our study were to determine cell size dynamics and vi...

  7. Principles of bacterial cell-size determination revealed by cell wall synthesis perturbations

    OpenAIRE

    Carolina Tropini; Timothy K. Lee; Jen Hsin; Samantha M. Desmarais; Tristan Ursell; Russell D. Monds; Kerwyn Casey Huang

    2014-01-01

    Although bacterial cell morphology is tightly controlled, the principles of size regulation remain elusive. In Escherichia coli, perturbation of cell-wall synthesis often results in similar morphologies, making it difficult to deconvolve the complex genotype-phenotype relationships underlying morphogenesis. Here we modulated cell width through heterologous expression of sequences encoding the essential enzyme PBP2 and through sublethal treatments with drugs that inhibit PBP2 and the MreB cyto...

  8. Regional variations in HDL metabolism in human fat cells: effect of cell size

    International Nuclear Information System (INIS)

    Abdominal obesity is related to reduced plasma high-density lipoprotein (HDL) cholesterol, and both are associated with cardiovascular disease risk. The authors have observed that plasma membranes from abdominal subcutaneous adipocytes have a greater HDL binding capacity than omental fat cell plasma membranes. The present study examined whether these binding characteristics could be due to differences in fat cell size or cholesterol concentration between the two adipose depots. Abdominal subcutaneous and deep omental fat were obtained from massively obese patients at surgery. Subcutaneous abdominal fat cells were significantly larger and their cellular cholesterol content greater than omental adipocytes. The uptake of HDL by collagenase-isolated fat cells was studied by incubating the cells for 2 h at 370C with 10 μg/ml 125I-HDL2 or 125I-HDL3. In both depots, the cellular uptake of 125I-HDL2 and 125I-HDL3 was specifically inhibited by addition of 25-fold excess unlabeled HDL and a close correlation was observed between the cellular uptake of 125I-HDL2 and 125I-HDL3. In obese patients, the uptake of 125I-HDL was higher in subcutaneous cells than in omental cells. The cellular 125I-HDL uptake was significantly correlated with adipocyte size and fat cell cholesterol content but not with adipocyte cholesterol concentration. These results suggest that the higher HDL uptake observed in subcutaneous cells compared with omental cells in obesity is the result of differences in adipocyte size rather than differences in the cholesterol concentration (cholesterol-to-triglyceride ratio). The increased interaction of HDL with hypertrophied abdominal adipocytes may play an important role in determining the lipid composition of HDL in obesity

  9. Regional variations in HDL metabolism in human fat cells: effect of cell size

    Energy Technology Data Exchange (ETDEWEB)

    Despres, J.; Fong, B.S.; Julien, P.; Jimenez, J.; Angel, A.

    1987-05-01

    Abdominal obesity is related to reduced plasma high-density lipoprotein (HDL) cholesterol, and both are associated with cardiovascular disease risk. The authors have observed that plasma membranes from abdominal subcutaneous adipocytes have a greater HDL binding capacity than omental fat cell plasma membranes. The present study examined whether these binding characteristics could be due to differences in fat cell size or cholesterol concentration between the two adipose depots. Abdominal subcutaneous and deep omental fat were obtained from massively obese patients at surgery. Subcutaneous abdominal fat cells were significantly larger and their cellular cholesterol content greater than omental adipocytes. The uptake of HDL by collagenase-isolated fat cells was studied by incubating the cells for 2 h at 37/sup 0/C with 10 ..mu..g/ml /sup 125/I-HDL/sub 2/ or /sup 125/I-HDL/sub 3/. In both depots, the cellular uptake of /sup 125/I-HDL/sub 2/ and /sup 125/I-HDL/sub 3/ was specifically inhibited by addition of 25-fold excess unlabeled HDL and a close correlation was observed between the cellular uptake of /sup 125/I-HDL/sub 2/ and /sup 125/I-HDL/sub 3/. In obese patients, the uptake of /sup 125/I-HDL was higher in subcutaneous cells than in omental cells. The cellular /sup 125/I-HDL uptake was significantly correlated with adipocyte size and fat cell cholesterol content but not with adipocyte cholesterol concentration. These results suggest that the higher HDL uptake observed in subcutaneous cells compared with omental cells in obesity is the result of differences in adipocyte size rather than differences in the cholesterol concentration (cholesterol-to-triglyceride ratio). The increased interaction of HDL with hypertrophied abdominal adipocytes may play an important role in determining the lipid composition of HDL in obesity.

  10. Relationship between Microcellular Foaming Injection Molding Process Parameters and Cell Size

    Institute of Scientific and Technical Information of China (English)

    HU Guang-hong; JIANG Chao-dong; CUI Zhen-shan

    2008-01-01

    In order to study the relationship between the main process parameters and the cell size, the mathematical model of cell growth of microcellular foaming injection process is built. Then numeric simulation is employed as experimental method, and the Taguchi method is used to analyze significance of effect of process parameters on the cell size. At last the process parameters are focused on melt temperature, injection time, mold temperature and pre- filled volume. The significance order from big to small of the effect of each process parameters on cell size is melt temperature, pre-filled volume, injection time, and mold temperature. On the basis of above research, the effect of each process parameter on cell size is further researched.Appropriate reduction of the melt temperature and increase of the we-filled volume can optimize the cell size effectively, while the effects of injection time and mold temperature on cell size are less significant.

  11. Positive correlation between size at initiation of chromosome replication in Escherichia coli and size at initiation of cell constriction.

    OpenAIRE

    Koppes, L J; Nanninga, N.

    1980-01-01

    The variability of (i) the length (size) at which cells initiate chromosome replication, (ii) the length at which they initiate cell constriction, and (iii) the time interval between these events has been estimated for Escherichia coli B/r K at two different slow growth rates. Steady-state cultures were pulse-labeled with [3H]thymidine and, after fixation, analyzed by electron microscopic radioautography. The coefficient of variation of length at initiation of chromosome replication was found...

  12. INCREMENT OF EFFICIENCY OF SOLAR CELL, WITH CHANGE SHAPE AND SIZE OF SOLAR PENNAL

    OpenAIRE

    S.K. Yadav; K.L. Yadav

    2014-01-01

    -To increase the efficiency of solar system with the help of change shape and size of solar pennal and arrangement of solar cell. And falling of light energy absorbed by solar cells and also dependence of solar energy, efficiency of solar cell on the multireflections of light on the solar cells. We formed different-different shape and size of solar pennal efficiency of solar cell, the internal and external reflections of light occurs many times with high energetic beam of ligh...

  13. Does Ploidy Level Directly Control Cell Size? Counterevidence from Arabidopsis Genetics

    OpenAIRE

    Tsukaya, Hirokazu

    2013-01-01

    Ploidy level affects cell size in many organisms, and ploidy-dependent cell enlargement has been used to breed many useful organisms. However, how polyploidy affects cell size remains unknown. Previous studies have explored changes in transcriptome data caused by polyploidy, but have not been successful. The most naïve theory explaining ploidy-dependent cell enlargement is that increases in gene copy number increase the amount of protein, which in turn increases the cell volume. This hypothes...

  14. Daughter-specific transcription factors regulate cell size control in budding yeast.

    Directory of Open Access Journals (Sweden)

    Stefano Di Talia

    2009-10-01

    Full Text Available In budding yeast, asymmetric cell division yields a larger mother and a smaller daughter cell, which transcribe different genes due to the daughter-specific transcription factors Ace2 and Ash1. Cell size control at the Start checkpoint has long been considered to be a main regulator of the length of the G1 phase of the cell cycle, resulting in longer G1 in the smaller daughter cells. Our recent data confirmed this concept using quantitative time-lapse microscopy. However, it has been proposed that daughter-specific, Ace2-dependent repression of expression of the G1 cyclin CLN3 had a dominant role in delaying daughters in G1. We wanted to reconcile these two divergent perspectives on the origin of long daughter G1 times. We quantified size control using single-cell time-lapse imaging of fluorescently labeled budding yeast, in the presence or absence of the daughter-specific transcriptional regulators Ace2 and Ash1. Ace2 and Ash1 are not required for efficient size control, but they shift the domain of efficient size control to larger cell size, thus increasing cell size requirement for Start in daughters. Microarray and chromatin immunoprecipitation experiments show that Ace2 and Ash1 are direct transcriptional regulators of the G1 cyclin gene CLN3. Quantification of cell size control in cells expressing titrated levels of Cln3 from ectopic promoters, and from cells with mutated Ace2 and Ash1 sites in the CLN3 promoter, showed that regulation of CLN3 expression by Ace2 and Ash1 can account for the differential regulation of Start in response to cell size in mothers and daughters. We show how daughter-specific transcriptional programs can interact with intrinsic cell size control to differentially regulate Start in mother and daughter cells. This work demonstrates mechanistically how asymmetric localization of cell fate determinants results in cell-type-specific regulation of the cell cycle.

  15. Scattering properties of microalgae: the effect of cell size and cell wall

    Science.gov (United States)

    Svensen, Øyvind; Frette, Øyvind; Rune Erga, Svein

    2007-08-01

    The main objective of this work was to investigate how the cell size and the presence of a cell wall influence the scattering properties of the green microalgae Chlamydomonas reinhardtii. The growth cycle of two strains, one with a cell wall and one without, was synchronized to be in the same growth phase. Measurements were conducted at two different phases of the growth cycle on both strains of the algae. It was found that the shape of the scattering phase function was very similar for both strains at both growth phases, but the regular strain with a cell wall scatters more strongly than the wall-less mutant. It was also found that the mutant strain has a stronger increase in scattering than the regular strain, as the algae grow, and that the scattering from the regular strain is more wavelength dependent than from the mutant strain.

  16. Low Temperature and Polyploidy Result in Larger Cell and Body Size in an Ectothermic Vertebrate.

    Science.gov (United States)

    Hermaniuk, Adam; Rybacki, Mariusz; Taylor, Jan R E

    2016-01-01

    Previous studies reported that low temperatures result in increases in both cell size and body size in ectotherms that may explain patterns of geographic variation of their body size across latitudinal ranges. Also, polyploidy showed the same effect on body size in invertebrates. In vertebrates, despite their having larger cells, no clear effect of polyploidy on body size has been found. This article presents the relationship between temperature, cell size, growth rate, and body size in diploid and polyploid hybridogenetic frog Pelophylax esculentus reared as tadpoles at 19° and 24°C. The size of cells was larger in both diploid and triploid tadpoles at 19°C, and triploids had larger cells at both temperatures. In diploid and triploid froglets, the temperature in which they developed as tadpoles did not affect the size of their cells, but triploids still had larger cells. Triploid tadpoles grew faster than diploids at 19°C and had larger body mass; there was no clear difference between ploidies in growth rate at 24°C. This indicates better adaptation of triploid tadpoles to cold environment. This is the first report on the increase of body mass of a polyploid vertebrate caused by low temperature, and we showed relationship between increase in cell size and increased body mass. The large body mass of triploids may provide a selective advantage, especially in colder environments, and this may explain the prevalence of triploids in the northern parts of the geographic range of P. esculentus. PMID:27082722

  17. Sorting of cells of the same size, shape, and cell cycle stage for a single cell level assay without staining

    Directory of Open Access Journals (Sweden)

    Yomo Tetsuya

    2006-06-01

    Full Text Available Abstract Background Single-cell level studies are being used increasingly to measure cell properties not directly observable in a cell population. High-performance data acquisition systems for such studies have, by necessity, developed in synchrony. However, improvements in sample purification techniques are also required to reveal new phenomena. Here we assessed a cell sorter as a sample-pretreatment tool for a single-cell level assay. A cell sorter is routinely used for selecting one type of cells from a heterogeneous mixture of cells using specific fluorescence labels. In this case, we wanted to select cells of exactly the same size, shape, and cell-cycle stage from a population, without using a specific fluorescence label. Results We used four light scatter parameters: the peak height and area of the forward scatter (FSheight and FSarea and side scatter (SSheight and SSarea. The rat pheochromocytoma PC12 cell line, a neuronal cell line, was used for all experiments. The living cells concentrated in the high FSarea and middle SSheight/SSarea fractions. Single cells without cell clumps were concentrated in the low SS and middle FS fractions, and in the higher FSheight/FSarea and SSheight/SSarea fractions. The cell populations from these viable, single-cell-rich fractions were divided into twelve subfractions based on their FSarea-SSarea profiles, for more detailed analysis. We found that SSarea was proportional to the cell volume and the FSarea correlated with cell roundness and elongation, as well as with the level of DNA in the cell. To test the method and to characterize the basic properties of the isolated single cells, sorted cells were cultured in separate wells. The cells in all subfractions survived, proliferated and differentiated normally, suggesting that there was no serious damage. The smallest, roundest, and smoothest cells had the highest viability. There was no correlation between proliferation and differentiation. NGF increases

  18. Does ploidy level directly control cell size? Counterevidence from Arabidopsis genetics.

    Directory of Open Access Journals (Sweden)

    Hirokazu Tsukaya

    Full Text Available Ploidy level affects cell size in many organisms, and ploidy-dependent cell enlargement has been used to breed many useful organisms. However, how polyploidy affects cell size remains unknown. Previous studies have explored changes in transcriptome data caused by polyploidy, but have not been successful. The most naïve theory explaining ploidy-dependent cell enlargement is that increases in gene copy number increase the amount of protein, which in turn increases the cell volume. This hypothesis can be evaluated by examining whether any strains, mutants, or transgenics show the same cell size before and after a tetraploidization event. I performed this experiment by tetraploidizing various mutants and transgenics of Arabidopsis thaliana, which show a wide range in cell size, and found that the ploidy-dependent increase in cell volume is genetically regulated. This result is not in agreement with the theory described above.

  19. Effect of Porosity and Cell Size on the Dynamic Compressive Properties of Aluminum Alloy Foams

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The dynamic mechanical properties of open-cell aluminum alloy foams with different relative densities and cell sizeshave been investigated by compressive tests. The strain rates varied from 700 s-1 to 2600 s-1. The experimentalresults showed that the dynamic compressive stress-strain curves exhibited a typical three-stage behavior: elastic,plateau and densification. The dynamic compressive strength of foams is affected not only by the relative densitybut also by the strain rate and cell size. Aluminum alloy foams with higher relative density or smaller cell size aremore sensitive to the strain rate than foams with lower relative density or larger cell size.

  20. A cell-counting factor regulating structure size in Dictyostelium

    OpenAIRE

    Brock, Debra A; Gomer, Richard H.

    1999-01-01

    Developing Dictyostelium cells form large aggregation streams that break up into groups of 0.2 × 105 to 1 × 105 cells. Each group then becomes a fruiting body. smlA cells oversecrete an unknown factor that causes aggregation streams to break up into groups of ∼5 × 103 cells and thus form very small fruiting bodies. We have purified the counting factor and find that it behaves as a complex of polypeptides with an effective molecular mass of 450 kD. One of the polypeptides is a 40-kD hydrophili...

  1. Clear cell renal cell carcinoma: Contrast-enhanced ultrasound features relation to tumor size

    International Nuclear Information System (INIS)

    Objectives: To analyze the contrast-enhanced ultrasound (CEUS) features of clear cell renal cell carcinoma (CCRCC) in relation to tumor size. Materials and methods: The CEUS appearance of 92 CCRCCs confirmed pathologically were retrospectively analyzed. Tumor size was stratified into six groups with a 1 cm interval. For each lesion, the degree of enhancement, the homogeneity of enhancement and the presence of pseudocapsule sign were evaluated and compared with the pathologic findings. Results: The tumors of groups I-VI were counted for 13, 26, 21, 11, 10 and 11, respectively. All the CCRCCs mainly showed a marked enhancement, and there was no statistically significance between the degree of enhancement and tumor size (P > 0.05). However, both homogeneity of enhancement and frequency of pseudocapsule correlated well with the tumor size (P 3 cm (9%; P 5 cm (66%, 23%, 24%, respectively; P < 0.01). On the pathologic examinations, the mean MVD was significantly higher in marked enhancement tumors than slight enhancement tumors (46.0 ± 15.9, 27.5 ± 8.3, respectively; P < 0.01). Any tumors with a heterogeneous enhancement pattern were accompanied by intratumoral necrosis or cysts on histologic specimen. A pseudocapsule was seen at pathology in all the 46 cases with perilesional enhancement and 4 of 46 tumors without perilesional enhancement at CEUS. Conclusion: CEUS features of CCRCCs vary with the size of the tumor, especially in the homogeneity of enhancement and the presence of pseudocapsule sign. CEUS is effective in demonstrating the sonographic visualization of tumoral characteristics.

  2. Estimation of the detonation cell size in gases

    Science.gov (United States)

    Kuchinskii, V. V.; Onosov, I. I.

    2011-06-01

    A simple method to calculate the parameters of a shock wave in a space between the shock wave front and the Chapman-Jouguet plane is considered. Solving a velocity equation, one can calculate the pressure, density, and temperature of the gas, as well as determine the size of a detonation region in a one-dimensional approximation. The dependences of the detonation region size on input parameters are derived. From these dependences, one can estimate the run of the same curves in the real situation.

  3. Small-Size Resonant Photoacoustic Cell of Inclined Geometry for Gas Detection

    OpenAIRE

    Gorelik, A. V.; Ulasevich, A. L.; Nikonovich, F. N.; Zakharich, M. P.; Chebotar, A. I.; V. A. Firago; Stetsik, V. M.; Kazak, N. S.; Starovoitov, V. S.

    2009-01-01

    A photoacoustic cell intended for laser detection of trace gases is represented. The cell is adapted so as to enhance the gas-detection performance and, simultaneously, to reduce the cell size. The cell design provides an efficient cancellation of the window background (a parasite response due to absorption of laser beam in the cell windows) and acoustic isolation from the environment for an acoustic resonance of the cell. The useful photoacoustic response from a detected gas, window backgrou...

  4. Clear cell renal cell carcinoma: Contrast-enhanced ultrasound features relation to tumor size

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Jun [Department of ultrasound, Sixth People' s Hospital Affiliated to Shanghai Jiaotong University, Shanghai 200233 (China)], E-mail: tenine@163.com; Chen Yaqing [Department of ultrasound, Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092 (China)], E-mail: joychen1266@126.com; Zhou Yongchang [Department of ultrasound, Sixth People' s Hospital Affiliated to Shanghai Jiaotong University, Shanghai 200233 (China)], E-mail: zhouyongchang1130@163.com; Zhang Huizhen [Department of pathology, Sixth People' s Hospital Affiliated to Shanghai Jiaotong University, Shanghai 200233 (China)], E-mail: h_z_zhang@163.com

    2010-01-15

    Objectives: To analyze the contrast-enhanced ultrasound (CEUS) features of clear cell renal cell carcinoma (CCRCC) in relation to tumor size. Materials and methods: The CEUS appearance of 92 CCRCCs confirmed pathologically were retrospectively analyzed. Tumor size was stratified into six groups with a 1 cm interval. For each lesion, the degree of enhancement, the homogeneity of enhancement and the presence of pseudocapsule sign were evaluated and compared with the pathologic findings. Results: The tumors of groups I-VI were counted for 13, 26, 21, 11, 10 and 11, respectively. All the CCRCCs mainly showed a marked enhancement, and there was no statistically significance between the degree of enhancement and tumor size (P > 0.05). However, both homogeneity of enhancement and frequency of pseudocapsule correlated well with the tumor size (P < 0.01). Homogeneous enhancement was shown in 85%, 65%, 19%, 9%, 0% and 0% of the tumors in the six groups, respectively. In tumors {<=}3 cm the frequency (72%) of homogeneity was significantly higher than in tumors >3 cm (9%; P < 0.01). The detection rate of pseudocapsule sign in the six group was 23%, 62%, 71%, 64%, 50% and 0%, respectively. The frequency of pseudocapsule sign was significantly higher in tumors 2.1-5 cm than <2 cm and >5 cm (66%, 23%, 24%, respectively; P < 0.01). On the pathologic examinations, the mean MVD was significantly higher in marked enhancement tumors than slight enhancement tumors (46.0 {+-} 15.9, 27.5 {+-} 8.3, respectively; P < 0.01). Any tumors with a heterogeneous enhancement pattern were accompanied by intratumoral necrosis or cysts on histologic specimen. A pseudocapsule was seen at pathology in all the 46 cases with perilesional enhancement and 4 of 46 tumors without perilesional enhancement at CEUS. Conclusion: CEUS features of CCRCCs vary with the size of the tumor, especially in the homogeneity of enhancement and the presence of pseudocapsule sign. CEUS is effective in demonstrating the

  5. Robust organelle size extractions from elastic scattering measurements of single cells (Conference Presentation)

    Science.gov (United States)

    Cannaday, Ashley E.; Draham, Robert; Berger, Andrew J.

    2016-04-01

    The goal of this project is to estimate non-nuclear organelle size distributions in single cells by measuring angular scattering patterns and fitting them with Mie theory. Simulations have indicated that the large relative size distribution of organelles (mean:width≈2) leads to unstable Mie fits unless scattering is collected at polar angles less than 20 degrees. Our optical system has therefore been modified to collect angles down to 10 degrees. Initial validations will be performed on polystyrene bead populations whose size distributions resemble those of cell organelles. Unlike with the narrow bead distributions that are often used for calibration, we expect to see an order-of-magnitude improvement in the stability of the size estimates as the minimum angle decreases from 20 to 10 degrees. Scattering patterns will then be acquired and analyzed from single cells (EMT6 mouse cancer cells), both fixed and live, at multiple time points. Fixed cells, with no changes in organelle sizes over time, will be measured to determine the fluctuation level in estimated size distribution due to measurement imperfections alone. Subsequent measurements on live cells will determine whether there is a higher level of fluctuation that could be attributed to dynamic changes in organelle size. Studies on unperturbed cells are precursors to ones in which the effects of exogenous agents are monitored over time.

  6. Particle size dependence of hit probability for lung cells

    International Nuclear Information System (INIS)

    The macroscopic quantity 'absorbed dose' loses its validity to interpret the radiation-induced biological effects in the lung inhaled with particulate α-emitters like transuranic elements, because the doses to individual cells differ more widely than the range of doses over which the dose-response relationship can be regarded as linear. We intend to make up a three-dimensional model of parenchymal lung using a stack of actual histological sections in order to computer microscopic dose distribution around particulate α-emitters. This theoretical dosimetric approach will provide a scientific basis to the extrapolation of results of animal experiments utilizing high doses to man exposed to low level radioactivity and also to the understanding of biological effects associated with high LET radiations. Lung cells which survive α-particle hits were calculated, which will be a significant index of potential risk. Three models were assumed for the structure of parenchymal lung, which were 1) structureless lung of uniform density, 2) lattice of honeycomb pattern and 3) digital image of actual histological section of rat lung. The result shows that the survival cells decrease exponentially with the diameter of inhaled particles in any models. But the slope of the curve for the structureless lung is much greater than those for any other two models. This result suggests the validity of the dosimetric approach using actual histological section to estimate the inhalation risk of particulate α-emitters. (author)

  7. Vertical distribution of the prokaryotic cell size in the Mediterranean Sea

    Science.gov (United States)

    La Ferla, R.; Maimone, G.; Azzaro, M.; Conversano, F.; Brunet, C.; Cabral, A. S.; Paranhos, R.

    2012-12-01

    Distributions of prokaryotic cell size and morphology were studied in different areas of the Mediterranean Sea by using image analysis on samples collected from surface down to bathypelagic layers (max depth 4,900 m) in the Southern Tyrrhenian, Southern Adriatic and Eastern Mediterranean Seas. Distribution of cell size of prokaryotes in marine ecosystem is very often not considered, which makes our study first in the context of prokaryotic ecology. In the deep Mediterranean layers, an usually-not-considered form of carbon sequestration through prokaryotic cells has been highlighted, which is consistent with an increase in cell size with the depth of the water column. A wide range in prokaryotic cell volumes was observed (between 0.045 and 0.566 μm3). Increase in cell size with depth was opposed to cell abundance distribution. Our results from microscopic observations were confirmed by the increasing HNA/LNA ratio (HNA, cells with high nucleic acid content; LNA, cells with low nucleic acid content) along the water column. Implications of our results on the increasing cell size with depth are in the fact that the quantitative estimation of prokaryotic biomass changes along the water column and the amount of carbon sequestered in the deep biota is enhanced.

  8. Bacteria cell properties and grain size impact on bacteria transport and deposition in porous media.

    Science.gov (United States)

    Bai, Hongjuan; Cochet, Nelly; Pauss, André; Lamy, Edvina

    2016-03-01

    The simultaneous role of bacteria cell properties and porous media grain size on bacteria transport and deposition behavior was investigated in this study. Transport column experiments and numerical HYDRUS-1D simulations of three bacteria with different cell properties (Escherichia coli, Klebsiella oxytoca, and Rhodococcus rhodochrous) were carried out on two sandy media with different grain sizes, under saturated steady state flow conditions. Each bacterium was characterized by cell size and shape, cell motility, electrophoretic mobility, zeta potential, hydrophobicity and potential of interaction with the sand surface. Cell characteristics affected bacteria transport behavior in the fine sand, but similar bacteria breakthroughs and retardation factors observed in the coarse sand, indicated that bacteria transport was more depended on grain size than on bacteria cell properties. Retention decreased with increasing hydrophobicity and increased with increasing electrophoretic mobility of bacteria for both sand. The increasing sand grain size resulted in a decrease of bacteria retention, except for the motile E. coli, indicating that retention of this strain was more dependent on cell motility than on the sand grain size. Bacteria deposition coefficients obtained from numerical simulations of the retention profiles indicated that straining was an important mechanism affecting bacteria deposition of E. coli and Klebsiella sp., in the fine sand, but the attachment had the same importance as straining for R. rhodochrous. The results obtained in the coarse sand did not permit to discriminate the predominant mechanism of bacteria deposition and the relative implication of bacteria cell properties of this process. PMID:26705829

  9. Cell size, number and density in the retina ganglion cell layer of Pekin duck retina at different embryonic age

    OpenAIRE

    ZUO Shi-Feng; CHEN Yao-Xing; WANG Zi-Xu; Cao, Jing; Dong, Yu-lan

    2008-01-01

    Changes in cell size, number and density of the ganglion cell layer(GCL)of the Pekin duck retina were studied by using the methods of Nissl-staining and Scion Image picture processing at embryonic age day-11,14,17,20,23 and 26. The result indicated that the cells in GCL were small and round uniformly at E11 and E14. The large cells were first found at E17. From E11 to E26, cell size was increased 1.97-fold in the central area (CA) and 3.1-fold in the temple periphery (TP), and there was si...

  10. Co-variation of metabolic rates and cell-size in coccolithophores

    Directory of Open Access Journals (Sweden)

    G. Aloisi

    2015-04-01

    Full Text Available Coccolithophores are sensitive recorders of environmental change. The size of their coccosphere varies in the ocean along gradients of environmental conditions and provides a key for understanding the fate of this important phytoplankton group in the future ocean. But interpreting field changes in coccosphere size in terms of laboratory observations is hard, mainly because the marine signal reflects the response of multiple morphotypes to changes in a combination of environmental variables. In this paper I examine the large corpus of published laboratory experiments with coccolithophores looking for relations between environmental conditions, metabolic rates and cell size (a proxy for coccosphere size. I show that growth, photosynthesis, and to a lesser extent calcification, co-vary with cell size when pCO2, irradiance, temperature, nitrate, phosphate and iron conditions change. With the exception of phosphate and temperature, a change from limiting to non-limiting conditions always results in an increase in cell size. An increase in phosphate or temperature produces the opposite effect. The magnitude of the coccosphere size changes observed in the laboratory is comparable to that observed in the ocean. If the biological reasons behind the environment-metabolism-size link are understood, it will be possible to use coccosphere size changes in the modern ocean and in marine sediments to investigate the fate of coccolithophores in the future ocean. This reasoning can be extended to the size of coccoliths if, as recent experiments are starting to show, coccolith size reacts to environmental change proportionally to coccosphere size. I introduce a simple model that simulates the growth rate and the size of cells forced by nitrate and phosphate concentrations. By considering a simple rule that allocates the energy flow from nutrient acquisition to cell structure (biomass and cell maturity (biological complexity, eventually leading to cell division

  11. Scattering pulse of label free fine structure cells to determine the size scale of scattering structures

    Science.gov (United States)

    Zhang, Lu; Chen, Xingyu; Zhang, Zhenxi; Chen, Wei; Zhao, Hong; Zhao, Xin; Li, Kaixing; Yuan, Li

    2016-04-01

    Scattering pulse is sensitive to the morphology and components of each single label-free cell. The most direct detection result, label free cell's scattering pulse is studied in this paper as a novel trait to recognize large malignant cells from small normal cells. A set of intrinsic scattering pulse calculation method is figured out, which combines both hydraulic focusing theory and small particle's scattering principle. Based on the scattering detection angle ranges of widely used flow cytometry, the scattering pulses formed by cell scattering energy in forward scattering angle 2°-5° and side scattering angle 80°-110° are discussed. Combining the analysis of cell's illuminating light energy, the peak, area, and full width at half maximum (FWHM) of label free cells' scattering pulses for fine structure cells with diameter 1-20 μm are studied to extract the interrelations of scattering pulse's features and cell's morphology. The theoretical and experimental results show that cell's diameter and FWHM of its scattering pulse agree with approximate linear distribution; the peak and area of scattering pulse do not always increase with cell's diameter becoming larger, but when cell's diameter is less than about 16 μm the monotone increasing relation of scattering pulse peak or area with cell's diameter can be obtained. This relationship between the features of scattering pulse and cell's size is potentially a useful but very simple criterion to distinguishing malignant and normal cells by their sizes and morphologies in label free cells clinical examinations.

  12. Nck adaptors are positive regulators of the size and sensitivity of the T-cell repertoire

    OpenAIRE

    Roy, Edwige; Togbe, Dieudonnée; Holdorf, Amy D.; Trubetskoy, Dmitry; Nabti, Sabrina; Küblbeck, Günter; Klevenz, Alexandra; Kopp-Schneider, Annette; Leithäuser, Frank; Möller, Peter; Bladt, Friedhelm; Hämmerling, Günter; Arnold, Bernd; Pawson, Tony; Tafuri, Anna

    2010-01-01

    The size and sensitivity of the T-cell repertoire governs the effectiveness of immune responses against invading pathogens. Both are modulated by T-cell receptor (TCR) activity through molecular mechanisms, which remain unclear. Here, we provide genetic evidence that the SH2/SH3 domain containing proteins Nck lower the threshold of T-cell responsiveness. The hallmarks of Nck deletion were T-cell lymphopenia and hyporeactivity to TCR-mediated stimulation. In the absence of the Nck adaptors, pe...

  13. Bone cell-materials interaction on alumina ceramics with different grain sizes

    International Nuclear Information System (INIS)

    The objective of this work was to study adhesion, proliferation and differentiation of osteoblast cells (OPC1) on alumina ceramic, a bio-inert material. Alumina ceramic with different average grain sizes, 1 μm and 12 μm, respectively, were used in as-prepared condition without any grinding and polishing to understand the influence of grain size on cell-material interactions. Scanning electron microscopy and confocal imaging were used to study attachment, adhesion and differentiation of OPC1 cells. Cells attached, proliferated and differentiated well on both the substrates. Adhesion of cells, as assessed by observing the production of vinculin, was found to be a consistent phenomenon on both the substrates. On day 5 of cell culture, significant cell-attachment was observed and vinculin was detected throughout cytoplasm. MTT assay showed that proliferation of OPC1 cells was consistently higher in the case of 12 μm-alumina. Cells of different morphology, nodular, plate-like as well as elongated, were found to get anchored at grains, grain boundaries as well as pores. On day 16, there were clear signs of mineralization as well. Over all, alumina with average grain size of 12 μm showed better cell-attachment, growth and differentiation compared to 1 μm grain size samples.

  14. The Influence of Genome and Cell Size on Brain Morphology in Amphibians.

    Science.gov (United States)

    Roth, Gerhard; Walkowiak, Wolfgang

    2015-09-01

    In amphibians, nerve cell size is highly correlated with genome size, and increases in genome and cell size cause a retardation of the rate of development of nervous (as well as nonnervous) tissue leading to secondary simplification. This yields an inverse relationship between genome and cell size on the one hand and morphological complexity of the tectum mesencephali as the main visual center, the size of the torus semicircularis as the main auditory center, the size of the amphibian papilla as an important peripheral auditory structure, and the size of the cerebellum as a major sensorimotor center. Nervous structures developing later (e.g., torus and cerebellum) are more affected by secondary simplification than those that develop earlier (e.g., the tectum). This effect is more prominent in salamanders and caecilians than in frogs owing to larger genome and cells sizes in the former two taxa. We hypothesize that because of intragenomic evolutionary processes, important differences in brain morphology can arise independently of specific environmental selection. PMID:26261281

  15. Cell size, number and density in the retina ganglion cell layer of Pekin duck retina at different embryonic age

    Directory of Open Access Journals (Sweden)

    ZUO Shi-Feng

    2008-12-01

    Full Text Available Changes in cell size, number and density of the ganglion cell layer(GCL)of the Pekin duck retina were studied by using the methods of Nissl-staining and Scion Image picture processing at embryonic age day-11,14,17,20,23 and 26. The result indicated that the cells in GCL were small and round uniformly at E11 and E14. The large cells were first found at E17. From E11 to E26, cell size was increased 1.97-fold in the central area (CA and 3.1-fold in the temple periphery (TP, and there was significant difference among all embryonic ages. During the growth and development of embryo, the total number of cells in GCL was increased to 2.03×106 cells at E17, and then decreased significantly with age. Differentiation of the central-peripheral gradient in cell density has been performed at E11. Cell density in CA was up to the maximal value (2.54×104 cells/mm2 at E17 and then decreased. However, cell density was decreased constantly in the peripheral area, especially in TP. In conclusion, E17 is the most important point for the retina during the embryonic developmental of Pekin duck, accompanying changes in cell size, number and density in GCL [Acta Zoologica Sinica 54(6: 1082 – 1088, 2008].

  16. Deformability and size-based cancer cell separation using an integrated microfluidic device.

    Science.gov (United States)

    Pang, Long; Shen, Shaofei; Ma, Chao; Ma, Tongtong; Zhang, Rui; Tian, Chang; Zhao, Lei; Liu, Wenming; Wang, Jinyi

    2015-11-01

    Cell sorting by filtration techniques offers a label-free approach for cell separation on the basis of size and deformability. However, filtration is always limited by the unpredictable variation of the filter hydrodynamic resistance due to cell accumulation and clogging in the microstructures. In this study, we present a new integrated microfluidic device for cell separation based on the cell size and deformability by combining the microstructure-constricted filtration and pneumatic microvalves. Using this device, the cell populations sorted by the microstructures can be easily released in real time for subsequent analysis. Moreover, the periodical sort and release of cells greatly avoided cell accumulation and clogging and improved the selectivity. Separation of cancer cells (MCF-7, MDA-MB-231 and MDA231-LM2) with different deformability showed that the mixture of the less flexible cells (MCF-7) and the flexible cells (MDA-MB-231 and MDA231-LM2) can be well separated with more than 75% purity. Moreover, the device can be used to separate cancer cells from the blood samples with more than 90% cell recovery and more than 80% purity. Compared with the current filtration methods, the device provides a new approach for cancer cell separation with high collection recovery and purity, and also, possesses practical potential to be applied as a sample preparation platform for fundamental studies and clinical applications. PMID:26366443

  17. System Size Resonance Associated with Canard Phenomenon in a Biological Cell System

    Institute of Scientific and Technical Information of China (English)

    Juan Ma; Hong-ying Li; Zhong-huai Hou; Hou-wen Xin

    2008-01-01

    The influence of internal noise on the calcium oscillations is studied. It is found that stochastic calcium oscillations occur when the internal noise is considered, while the corresponding deterministic dynamics only yields a steady state. Also, the performance of such oscillations shows two maxima with the variation of the system size, indicating the occurrence of system size resonance. This behavior is found to be intimately connected with the canard phenomenon. Interestingly, it is also found that one of the optimal system sizes matches well with the real cell size, and such a match is robust to the variation of the control parameters.

  18. In vitro toxicity of different-sized ZnO nanoparticles in Caco-2 cells

    Science.gov (United States)

    Kang, Tianshu; Guan, Rongfa; Chen, Xiaoqiang; Song, Yijuan; Jiang, Han; Zhao, Jin

    2013-11-01

    There has been rapid growth in nanotechnology in both the public and private sectors worldwide, but concern about nanosafety exists. To assess size-dependent cytotoxicity on human cancer cells, we studied the cytotoxic effect of three kinds of zinc oxide nanoparticles (ZnO NPs) on human epithelial colorectal adenocarcinoma (Caco-2) cells. Nanoparticles were first characterized by size, distribution, and intensity. Multiple assays have been adopted to measure the cell activity and oxidative stress. The cytotoxicity of ZnO NPs was time dependent and dose dependent. The 24-h exposure was chosen to confirm the viability and accessibility of the cells and taken as the appropriate time for the following test system. The IC50 value was found at a low concentration. The oxidative stress elicited a significant reduction in glutathione with increase in reactive oxygen species and lactate dehydrogenase. The toxicity resulted in a deletion of cells in the G1 phase and an accumulation of cells in the S and G2/M phases. One type of metallic oxide (ZnO) exerted different cytotoxic effects according to different particle sizes. Data from the previous experiments showed that 26-nm ZnO NPs appeared to have the highest toxicity to Caco-2 cells. The study demonstrated the toxicity of ZnO NPs to Caco-2 cells and the impact of particle size, which could be useful in the medical applications.

  19. Support for the initial attachment, growth and differentiation of MG-63 cells: a comparison between nano-size hydroxyapatite and micro-size hydroxyapatite in composites.

    Science.gov (United States)

    Filová, Elena; Suchý, Tomáš; Sucharda, Zbyněk; Supová, Monika; Zaloudková, Margit; Balík, Karel; Lisá, Věra; Slouf, Miroslav; Bačáková, Lucie

    2014-01-01

    Hydroxyapatite (HA) is considered to be a bioactive material that favorably influences the adhesion, growth, and osteogenic differentiation of osteoblasts. To optimize the cell response on the hydroxyapatite composite, it is desirable to assess the optimum concentration and also the optimum particle size. The aim of our study was to prepare composite materials made of polydimethylsiloxane, polyamide, and nano-sized (N) or micro-sized (M) HA, with an HA content of 0%, 2%, 5%, 10%, 15%, 20%, 25% (v/v) (referred to as N0-N25 or M0-M25), and to evaluate them in vitro in cultures with human osteoblast-like MG-63 cells. For clinical applications, fast osseointegration of the implant into the bone is essential. We observed the greatest initial cell adhesion on composites M10 and N5. Nano-sized HA supported cell growth, especially during the first 3 days of culture. On composites with micro-size HA (2%-15%), MG-63 cells reached the highest densities on day 7. Samples M20 and M25, however, were toxic for MG-63 cells, although these composites supported the production of osteocalcin in these cells. On N2, a higher concentration of osteopontin was found in MG-63 cells. For biomedical applications, the concentration range of 5%-15% (v/v) nano-size or micro-size HA seems to be optimum. PMID:25125978

  20. Lateral inhibition-induced pattern formation controlled by the size and geometry of the cell.

    Science.gov (United States)

    Seirin Lee, Sungrim

    2016-09-01

    Pattern formation in development biology is one of the fundamental processes by which cells change their functions. It is based on the communication of cells via intra- and intercellular dynamics of biochemicals. Thus, the cell is directly involved in biochemical interactions. However, many theoretical approaches describing biochemical pattern formation have usually neglected the cell's role or have simplified the subcellular process without considering cellular aspects despite the cell being the environment where biochemicals interact. On the other hand, recent experimental observations suggest that a change in the physical conditions of cell-to-cell contact can result in a change in cell fate and tissue patterning in a lateral inhibition system. Here we develop a mathematical model by which biochemical dynamics can be directly observed with explicitly expressed cell structure and geometry in higher dimensions, and reconsider pattern formation by lateral inhibition of the Notch-Delta signaling pathway. We explore how the physical characteristic of cell, such as cell geometry or size, influences the biochemical pattern formation in a multi-cellular system. Our results suggest that a property based on cell geometry can be a novel mechanism for symmetry breaking inducing cell asymmetry. We show that cell volume can critically influence cell fate determination and pattern formation at the tissue level, and the surface area of the cell-to-cell contact can directly affect the spatial range of patterning. PMID:27229622

  1. Dermal papilla cell number specifies hair size, shape and cycling and its reduction causes follicular decline

    OpenAIRE

    Chi, Woo; Wu, Eleanor; Morgan, Bruce A.

    2013-01-01

    Although the hair shaft is derived from the progeny of keratinocyte stem cells in the follicular epithelium, the growth and differentiation of follicular keratinocytes is guided by a specialized mesenchymal population, the dermal papilla (DP), that is embedded in the hair bulb. Here we show that the number of DP cells in the follicle correlates with the size and shape of the hair produced in the mouse pelage. The same stem cell pool gives rise to hairs of different sizes or types in successiv...

  2. Coherent population trapping on 87Rb atoms in small-size absorption cells with buffer gas

    Science.gov (United States)

    Ermak, S. V.; Petrenko, M. V.; Semenov, V. V.

    2016-02-01

    Coherent population trapping (CPT) on 87Rb atoms in neon atmosphere has been studied in small-size glass absorption cells under conditions of pumping with narrow-band laser radiation at the D2 line of the main doublet. Parameters of the absorption signal have been measured in 3-mm-diameter cells at buffer gas (Ne) pressures varied within 200-400 Torr, cell temperatures within 65-120°C, and pumping radiation power densities within 30-400 μW/cm2. Optimum values of the buffer gas pressures, cell temperature, and pumping power are determined at which the short-term instability of the resonance line is at minimum. Orientational shifts of the CPT resonance signal in gas-filled cells and small-size cells with antirelaxation coating have been compared.

  3. Correlation of Red Blood Cell Aggregate Size with Transmitted Light Intensity Distributions

    Science.gov (United States)

    Hitt, Darren L.

    1998-11-01

    Under sufficiently low shear rates, such as those encountered in the microcirculation, human red blood cells are known to form aggregate structures (`rouleaux'). These aggregates may range in size from a simple chain containing only a few cells to complex three-dimensional structures containing tens of cells. Previous studies have attempted to characterize the aggregate size by examining the spatial distribution of transmitted light intensity resulting from transillumination of the blood flow. For experiments performed in vitro and in vivo, spectral analysis of the transmitted light intensities has shown that the presence of aggregates in the flow can linked with an increase in the spectral power at small wavenumbers. The magnitudes of the affected wavenumbers correspond to structures considerably larger than individual cells. A precise numerical correlation, however, is difficult to establish. In this work, computer simulations of aggregating blood flow are used along with statistical considerations in an attempt to better correlate the observed spectral trends with actual aggregate size.

  4. What is more important for radiated power from cells - Size or geometry?

    Czech Academy of Sciences Publication Activity Database

    Havelka, D.; Cifra, Michal; Vrba, J.

    Vol. 329. Bristol: IOP, 2011 - (Cifra, M.; Pokorny, J.; Kučera, O.), 012014 ISSN 1742-6588. [9th International Frohlich's Symposium on Electrodynamic Activity of Living Cells - Including Microtubule Coherent Modes and Cancer Cell Physics. Praha (CZ), 01.07.2011-03.07.2011] R&D Projects: GA ČR(CZ) GAP102/11/0649 Institutional support: RVO:67985882 Keywords : Cell size * Cytoskeletons * Comparative analysis Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  5. Assessing T cell clonal size distribution: a non-parametric approach

    OpenAIRE

    Bolkhovskaya, Olesya V.; Daniil Yu Zorin; Ivanchenko, Mikhail V.

    2014-01-01

    Clonal structure of the human peripheral T-cell repertoire is shaped by a number of homeostatic mechanisms, including antigen presentation, cytokine and cell regulation. Its accurate tuning leads to a remarkable ability to combat pathogens in all their variety, while systemic failures may lead to severe consequences like autoimmune diseases. Here we develop and make use of a non-parametric statistical approach to assess T cell clonal size distributions from recent next generation sequencing d...

  6. Control of cell proliferation, endoreduplication, cell size, and cell death by the retinoblastoma-related pathway in maize endosperm

    KAUST Repository

    Sabelli, Paolo A.

    2013-04-22

    The endospermof cereal grains is one of the most valuable products of modern agriculture. Cereal endosperm development comprises different phases characterized by mitotic cell proliferation, endoreduplication, the accumulation of storage compounds, and programmed cell death. Although manipulation of these processes could maximize grain yield, how they are regulated and integrated is poorly understood. We show that the Retinoblastoma-related (RBR) pathway controls key aspects of endosperm development in maize. Down-regulation of RBR1 by RNAi resulted in up-regulation of RBR3-type genes, as well as the MINICHROMOSOME MAINTENANCE 2-7 gene family and PROLIFERATING CELL NUCLEAR ANTIGEN, which encode essential DNA replication factors. Both the mitotic and endoreduplication cell cycles were stimulated. Developing transgenic endosperm contained 42-58% more cells and ~70% more DNA than wild type, whereas there was a reduction in cell and nuclear sizes. In addition, cell death was enhanced. The DNA content of mature endosperm increased 43% upon RBR1 downregulation, whereas storage protein content and kernel weight were essentially not affected. Down-regulation of both RBR1 and CYCLIN DEPENDENT KINASE A (CDKA);1 indicated that CDKA;1 is epistatic to RBR1 and controls endoreduplication through an RBR1- dependent pathway. However, the repressive activity of RBR1 on downstream targets was independent from CDKA;1, suggesting diversification of RBR1 activities. Furthermore, RBR1 negatively regulated CDK activity, suggesting the presence of a feedback loop. These results indicate that the RBR1 pathway plays a major role in regulation of different processes during maize endosperm development and suggest the presence of tissue/organlevel regulation of endosperm/seed homeostasis.

  7. Effects of meal size and composition on incretin, alpha-cell, and beta-cell responses.

    Science.gov (United States)

    Rijkelijkhuizen, Josina M; McQuarrie, Kelly; Girman, Cynthia J; Stein, Peter P; Mari, Andrea; Holst, Jens J; Nijpels, Giel; Dekker, Jacqueline M

    2010-04-01

    The incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) regulate postprandial insulin release from the beta-cells. We investigated the effects of 3 standardized meals with different caloric and nutritional content in terms of postprandial glucose, insulin, glucagon, and incretin responses. In a randomized crossover study, 18 subjects with type 2 diabetes mellitus and 6 healthy volunteers underwent three 4-hour meal tolerance tests (small carbohydrate [CH]-rich meal, large CH-rich meal, and fat-rich meal). Non-model-based and model-based estimates of beta-cell function and incremental areas under the curve of glucose, insulin, C-peptide, glucagon, GLP-1, and GIP were calculated. Mixed models and Friedman tests were used to test for differences in meal responses. The large CH-rich meal and fat-rich meal resulted in a slightly larger insulin response as compared with the small CH-rich meal and led to a slightly shorter period of hyperglycemia, but only in healthy subjects. Model-based insulin secretion estimates did not show pronounced differences between meals. Both in healthy individuals and in those with diabetes, more CH resulted in higher GLP-1 release. In contrast with the other meals, GIP release was still rising 2 hours after the fat-rich meal. The initial glucagon response was stimulated by the large CH-rich meal, whereas the fat-rich meal induced a late glucagon response. Fat preferentially stimulates GIP secretion, whereas CH stimulates GLP-1 secretion. Differences in meal size and composition led to differences in insulin and incretin responses but not to differences in postprandial glucose levels of the well-controlled patients with diabetes. PMID:19846181

  8. Iso-acoustic focusing of cells for size-insensitive acousto-mechanical phenotyping

    Science.gov (United States)

    Augustsson, Per; Karlsen, Jonas T.; Su, Hao-Wei; Bruus, Henrik; Voldman, Joel

    2016-05-01

    Mechanical phenotyping of single cells is an emerging tool for cell classification, enabling assessment of effective parameters relating to cells' interior molecular content and structure. Here, we present iso-acoustic focusing, an equilibrium method to analyze the effective acoustic impedance of single cells in continuous flow. While flowing through a microchannel, cells migrate sideways, influenced by an acoustic field, into streams of increasing acoustic impedance, until reaching their cell-type specific point of zero acoustic contrast. We establish an experimental procedure and provide theoretical justifications and models for iso-acoustic focusing. We describe a method for providing a suitable acoustic contrast gradient in a cell-friendly medium, and use acoustic forces to maintain that gradient in the presence of destabilizing forces. Applying this method we demonstrate iso-acoustic focusing of cell lines and leukocytes, showing that acoustic properties provide phenotypic information independent of size.

  9. Nck adaptors are positive regulators of the size and sensitivity of the T-cell repertoire.

    Science.gov (United States)

    Roy, Edwige; Togbe, Dieudonnée; Holdorf, Amy D; Trubetskoy, Dmitry; Nabti, Sabrina; Küblbeck, Günter; Klevenz, Alexandra; Kopp-Schneider, Annette; Leithäuser, Frank; Möller, Peter; Bladt, Friedhelm; Hämmerling, Günter; Arnold, Bernd; Pawson, Tony; Tafuri, Anna

    2010-08-31

    The size and sensitivity of the T-cell repertoire governs the effectiveness of immune responses against invading pathogens. Both are modulated by T-cell receptor (TCR) activity through molecular mechanisms, which remain unclear. Here, we provide genetic evidence that the SH2/SH3 domain containing proteins Nck lower the threshold of T-cell responsiveness. The hallmarks of Nck deletion were T-cell lymphopenia and hyporeactivity to TCR-mediated stimulation. In the absence of the Nck adaptors, peripheral T cells expressing a TCR with low avidity for self-antigens were strongly reduced, whereas an overall impairment of T-cell activation by weak antigenic stimulation was observed. Mechanistically, Nck deletion resulted in a significant decrease in calcium mobilization and ERK phosphorylation upon TCR engagement. Taken together, our findings unveil a crucial role for the Nck adaptors in shaping the T-cell repertoire to ensure maximal antigenic coverage and optimal T cell excitability. PMID:20709959

  10. Flow perfusion culture of human mesenchymal stem cells on coralline hydroxyapatite scaffolds with various pore sizes

    DEFF Research Database (Denmark)

    Bjerre, Lea; Bünger, Cody; Baatrup, Anette;

    2011-01-01

    study was to obtain a clinically relevant substitute size using a direct perfusion culture system. Human bone marrowderived mesenchymal stem cells were seeded on coralline hydroxyapatite scaffolds with 200 μm or 500 μm pores, and resulting constructs were cultured in a perfusion bioreactor or in static...... μm ones. Adhesion and proliferation of the cells was seen on both scaffold sizes, but the vitality and morphology of cells changed unfavorably during perfusion culture. In contrast to previous studies using spinner flask that show increased cellularity and osteogenic properties of cells when cultured...... scaffolds. Our conclusion is that the specific scaffold surface microstructure and culturing system flow dynamics has a great impact on cell distribution and proliferation and on osteogenic differentiation, and the data presented warrant careful selection of in vitro culture settings to meet the specific...

  11. Adsorption of hematite nanoparticles onto Caco-2 cells and the cellular impairments: effect of particle size

    International Nuclear Information System (INIS)

    The increasing applications of engineered nanomaterials nowadays have elevated the potential of human exposure through various routes including inhalation, skin penetration and digestion. To date there is scarce information on a quantitative description of the interactions between nanoparticles (NPs) and cell surfaces and the detrimental effects from the exposure. The purpose of this work was to study in vitro exposure of Caco-2 cells to hematite (α-Fe2O3) NPs and to determine the particle size effects on the adsorption behaviors. Cellular impairment was also investigated and compared. Hematite NPs were synthesized as part of this study with a discrete size distribution and uniform morphology examined by dynamic light scattering (DLS) and confirmed by transmission electron microscopy (TEM). Caco-2 cells were cultured as a model epithelium to mirror human intestinal cells and used to evaluate the impacts of the exposure to NPs by measuring transepithelial electrical resistance (TEER). Cell surface disruption, localization and translocation of NPs through the cells were analyzed with immunocytochemical staining and confocal microscopy. Results showed that hematite NPs had mean diameters of 26, 53, 76 and 98 nm and were positively charged with minor aggregation in the buffer solution. Adsorption of the four sizes of NPs on cells reached equilibrium within approximately 5 min but adsorption kinetics were found to be size-dependent. The adsorption rates expressed as mg m-2 min-1 were greater for large NPs (76 and 98 nm) than those for small NPs (26 and 53 nm). However, adsorption rates, expressed in units of m-2 min-1, were much greater for small NPs than large ones. After the adsorption equilibrium was reached, the adsorbed mass of NPs on a unit area of cells was calculated and showed no significant size dependence. Longer exposure time (>3 h) induced adverse cellular effects as indicated by the drop in TEER compared to the control cells without the exposure to NPs

  12. The control of cell growth and body size in Caenorhabditis elegans.

    Science.gov (United States)

    Tuck, Simon

    2014-02-01

    One of the most important ways in which animal species vary is in their size. Individuals of the largest animal ever thought to have lived, the blue whale (Balaenoptera musculus), can reach a weight of 190 t and a length of over 30 m. At the other extreme, among the smallest multicellular animals are males of the parasitic wasp, Dicopomorpha echmepterygis, which even as adults are just 140 μm in length. In terms of volume, these species differ by more than 14 orders of magnitude. Since size has such profound effects on an organism's ecology, anatomy and physiology, an important task for evolutionary biology and ecology is to account for why organisms grow to their characteristic sizes. Equally, a full description of an organism's development must include an explanation of how its growth and body size are regulated. Here I review research on how these processes are controlled in the nematode, Caenorhabditis elegans. Analyses of small and long mutants have revealed that in the worm, DBL-1, a ligand in the TGFβ superfamily family, promotes growth in a dose-dependent manner. DBL-1 signaling affects body size by stimulating the growth of syncytial hypodermal cells rather than controlling cell division. Signals from chemosensory neurons and from the gonad also modulate body size, in part, independently of DBL-1-mediated signaling. Organismal size and morphology is heavily influenced by the cuticle, which acts as the exoskeleton. Finally, I summarize research on several genes that appear to regulate body size by cell autonomously regulating cell growth throughout the worm. PMID:24262077

  13. Quantifying size-dependent interactions between fluorescently labeled polystyrene nanoparticles and mammalian cells

    Directory of Open Access Journals (Sweden)

    Varela Juan A

    2012-09-01

    Full Text Available Abstract Background Nanoparticles (NPs are currently used in a wide variety of fields such as technology, medicine and industry. Due to the novelty of these applications and to ensure their success, a precise characterization of the interactions between NPs and cells is essential. Findings The current study explores the uptake of polystyrene NPs by 1321N1 human astrocytoma and A549 human lung carcinoma cell lines. In this work we show for the first time a comparison of the uptake rates of fluorescently labeled carboxylated polystyrene (PS NPs of different sizes (20, 40 and 100 nm in two different cell types, keeping the number of NPs per unit volume constant for all sizes. We propose a reliable methodology to control the dose of fluorescently labeled NPs, by counting individual NPs using automated particle detection from 3D confocal microscopy images. The possibility of detecting individual NPs also allowed us to calculate the size of each nanoparticle and compare the fluorescence of single NPs across different sizes, thereby providing a robust platform for normalization of NP internalization experiments as measured by flow cytometry. Conclusions Our findings show that 40 nm NPs are internalized faster than 20 nm or 100 nm particles in both cell lines studied, suggesting that there is a privileged size gap in which the internalization of NPs is higher.

  14. Size-Dependent Photodynamic Anticancer Activity of Biocompatible Multifunctional Magnetic Submicron Particles in Prostate Cancer Cells.

    Science.gov (United States)

    Choi, Kyong-Hoon; Nam, Ki Chang; Malkinski, Leszek; Choi, Eun Ha; Jung, Jin-Seung; Park, Bong Joo

    2016-01-01

    In this study, newly designed biocompatible multifunctional magnetic submicron particles (CoFe₂O₄-HPs-FAs) of well-defined sizes (60, 133, 245, and 335 nm) were fabricated for application as a photosensitizer delivery agent for photodynamic therapy in cancer cells. To provide selective targeting of cancer cells and destruction of cancer cell functionality, basic cobalt ferrite (CoFe₂O₄) particles were covalently bonded with a photosensitizer (PS), which comprises hematoporphyrin (HP), and folic acid (FA) molecules. The magnetic properties of the CoFe₂O₄ particles were finely adjusted by controlling the size of the primary CoFe₂O₄ nanograins, and secondary superstructured composite particles were formed by aggregation of the nanograins. The prepared CoFe₂O₄-HP-FA exhibited high water solubility, good MR-imaging capacity, and biocompatibility without any in vitro cytotoxicity. In particular, our CoFe₂O₄-HP-FA exhibited remarkable photodynamic anticancer efficiency via induction of apoptotic death in PC-3 prostate cancer cells in a particle size- and concentration-dependent manner. This size-dependent effect was determined by the specific surface area of the particles because the number of HP molecules increased with decreasing size and increasing surface area. These results indicate that our CoFe₂O₄-HP-FA may be applicable for photodynamic therapy (PDT) as a PS delivery material and a therapeutic agent for MR-imaging based PDT owing to their high saturation value for magnetization and superparamagnetism. PMID:27607999

  15. Size effects of potato waste on its treatment by microbial fuel cell.

    Science.gov (United States)

    Du, Haixia; Li, Fusheng

    2016-05-01

    The performance of microbial fuel cell (MFC) in treating potato cubes with different sizes (the edge size of 3, 5 and 7 mm) was investigated. Current density was found lower as the size of potato cubes increased, even if the differences in their removal were less apparent. At the end of MFC operation for 81 days, both total and soluble chemical oxygen demand reached nearly identical values, irrespective of the potato sizes; and citrate and isobutyrate were two major organic acids remaining in the solutions. Bacterial community analysis using polymerase chain reaction, denaturing gradient gel electrophoresis and sequencing indicated that bacterial species on the anode and in the anodic solution were similar and did not change obviously with potato sizes, and that, in similarity with previous studies on potato-processing wastewater treatment, Proteobacteria and Firmicutes were two dominating phyla. Geobacter was found richer on the anode than in the anodic solutions. PMID:26583755

  16. Small-Size Resonant Photoacoustic Cell of Inclined Geometry for Gas Detection

    CERN Document Server

    Gorelik, A V; Nikonovich, F N; Zakharich, M P; Chebotar, A I; Firago, V A; Stetsik, V M; Kazak, N S; Starovoitov, V S

    2009-01-01

    A photoacoustic cell intended for laser detection of trace gases is represented. The cell is adapted so as to enhance the gas-detection performance and, simultaneously, to reduce the cell size. The cell design provides an efficient cancellation of the window background (a parasite response due to absorption of laser beam in the cell windows) and acoustic isolation from the environment for an acoustic resonance of the cell. The useful photoacoustic response from a detected gas, window background and noise are analyzed in demonstration experiments as functions of the modulation frequency for a prototype cell with the internal volume ~ 0.5 cm^3. The minimal detectable absorption for the prototype is estimated to be ~ 1.2 10^{-8} cm^{-1} W Hz^{-1/2}.

  17. Measurement and chemical kinetic model predictions of detonation cell size in methanol-oxygen mixtures

    Science.gov (United States)

    Eaton, R.; Zhang, B.; Bergthorson, J. M.; Ng, H. D.

    2012-03-01

    In this study, detonation cell sizes of methanol-oxygen mixtures are experimentally measured at different initial pressures and compositions. Good agreement is found between the experiment data and predictions based on the chemical length scales obtained from a detailed chemical kinetic model. To assess the detonation sensitivity in methanol-oxygen mixtures, the results are compared with those of hydrogen-oxygen and methane-oxygen mixtures. Based on the cell size comparison, it is shown that methanol-oxygen is more detonation sensitive than methane-oxygen but less sensitive than hydrogen-oxygen.

  18. Transporting of a Cell-Sized Phospholipid Vesicle Across Water/Oil Interface

    OpenAIRE

    Hase, Masahiko; Yamada, Ayako; Hamada, Tsutomu; Yoshikawa, Kenichi

    2006-01-01

    When a cell-sized water droplet, with a diameter of several tens of micro meter, is placed in oil containing phospholipids, a stable cell-sized vesicle is spontaneously formed as a water-in-oil phospholipid emulsion (W/O CE) with a phospholipid monolayer. We transferred the lipid vesicle thus formed in the oil phase to the water phase across the water/oil interface by micromanipulation, which suggests that the vesicle is transformed from a phospholipid monolayer as W/O CE into a bilayer. The ...

  19. Replicon sizes in mammalian cells as estimated by an x-ray plus bromodeoxyuridine photolysis method

    International Nuclear Information System (INIS)

    A new method is described for estimating replicon sizes in mammalian cells. Cultures were pulse labeled with [3H]thymidine ([3H]TdR) and bromodeoxyuridine (BrDUrd) for up to 1 h. The lengths of the resulting labeled regions of DNA, L/sub obs/, were estimated by a technique wherein the change in molecular weight of nascent DNA strands, induced by 313 nm light, is measured by velocity sedimentation in alkaline sucrose gradients. If cells are exposed to 1,000 rads of x rays immediately before pulse labeling, initiation of replicon operation is blocked, although chain elongation proceeds almost normally. Under these conditions L/sub obs/ continues to increase only until operating replicons have completed their replication. This value for L/sub obs/ then remains constant as long as the block to initiation remains and represents an estimate for the average size of replicons operating in the cells before x irradiation. For human diploid fibroblasts and human HeLa cells this estimated average size is approximately 17 μM, whereas for Chinese hamster ovary cells, the average replicon size is about 42 μM

  20. Dendritic field size and morphology of midget and parasol ganglion cells of the human retina.

    OpenAIRE

    Dacey, D M; Petersen, M R

    1992-01-01

    The visual system of the macaque monkey has provided a useful model for understanding the neural basis of human vision, yet, there are few detailed comparisons of neural populations other than photoreceptors for the two species. Using intracellular staining in an in vitro preparation of the isolated and intact human retina, we have characterized the relationship of dendritic field size to retinal eccentricity for the two major ganglion cell classes, the midget and the parasol cells. We report...

  1. Optimization and Evaluation of a Novel Size Based Circulating Tumor Cell Isolation System

    OpenAIRE

    Lei Xu; Xueying Mao; Ahmet Imrali; Ferrial Syed; Katherine Mutsvangwa; Daniel Berney; Paul Cathcart; John Hines; Jonathan Shamash; Yong-Jie Lu

    2015-01-01

    Isolation of circulating tumor cells (CTCs) from peripheral blood has the potential to provide a far easier "liquid biopsy" than tumor tissue biopsies, to monitor tumor cell populations during disease progression and in response to therapies. Many CTC isolation technologies have been developed. We optimized the Parsortix system, an epitope independent, size and compressibility-based platform for CTCs isolation, making it possible to harvest CTCs at the speed and sample volume comparable to st...

  2. Effect of hydroxyapatite particle size, morphology and crystallinity on proliferation of colon cancer HCT116 cells

    International Nuclear Information System (INIS)

    The aim of the present work is to chemically and physically characterize the synthesized Hydroxyapatite (HAp) micro and nanoparticles and to explore the inhibitory effect of nano-HAps on the in vitro growth of human colon cancerous cells HCT116. HAp powder was synthesized using three different routes to achieve micro and nanosized powders, with different morphologies and crystallinity. The synthesized powders were characterized using X-ray diffraction, FTIR spectroscopy and scanning electron microscope. The results showed that the average crystallite size of HAp powder varies from 11 nm to 177 nm and respective crystallinity of powder found to be in the range of 0.12 and 0.92. The effect of these physico-chemical properties of HAp powders on human colon cancer HCT116 cells inhibition was determined in vitro. It was found that decreasing the HAp powder crystallite size between 11 nm and 22 nm significantly increases the HCT116 cell inhibition. Our results demonstrate that apart from HAp powder size their crystallinity and morphology also play an important role in cellular inhibition of human colon cancer cells. - Highlights: • Chemically synthesized hydroxyapatite micro and nano-particles with different morphologies and crystallinity. • In vitro cell–material interaction showed that hydroxyapatite nano-particles inhibit colon cancer cells. • Human colon cancer cell inhibition also depends on crystallinity and morphology of HAp powder

  3. Effect of hydroxyapatite particle size, morphology and crystallinity on proliferation of colon cancer HCT116 cells

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Sangeeta; Das, Mitun, E-mail: mitun@cgcri.res.in; Balla, Vamsi Krishna

    2014-06-01

    The aim of the present work is to chemically and physically characterize the synthesized Hydroxyapatite (HAp) micro and nanoparticles and to explore the inhibitory effect of nano-HAps on the in vitro growth of human colon cancerous cells HCT116. HAp powder was synthesized using three different routes to achieve micro and nanosized powders, with different morphologies and crystallinity. The synthesized powders were characterized using X-ray diffraction, FTIR spectroscopy and scanning electron microscope. The results showed that the average crystallite size of HAp powder varies from 11 nm to 177 nm and respective crystallinity of powder found to be in the range of 0.12 and 0.92. The effect of these physico-chemical properties of HAp powders on human colon cancer HCT116 cells inhibition was determined in vitro. It was found that decreasing the HAp powder crystallite size between 11 nm and 22 nm significantly increases the HCT116 cell inhibition. Our results demonstrate that apart from HAp powder size their crystallinity and morphology also play an important role in cellular inhibition of human colon cancer cells. - Highlights: • Chemically synthesized hydroxyapatite micro and nano-particles with different morphologies and crystallinity. • In vitro cell–material interaction showed that hydroxyapatite nano-particles inhibit colon cancer cells. • Human colon cancer cell inhibition also depends on crystallinity and morphology of HAp powder.

  4. Mechanobiological induction of long-range contractility by diffusing biomolecules and size scaling in cell assemblies

    Science.gov (United States)

    Dasbiswas, K.; Alster, E.; Safran, S. A.

    2016-01-01

    Mechanobiological studies of cell assemblies have generally focused on cells that are, in principle, identical. Here we predict theoretically the effect on cells in culture of locally introduced biochemical signals that diffuse and locally induce cytoskeletal contractility which is initially small. In steady-state, both the concentration profile of the signaling molecule as well as the contractility profile of the cell assembly are inhomogeneous, with a characteristic length that can be of the order of the system size. The long-range nature of this state originates in the elastic interactions of contractile cells (similar to long-range “macroscopic modes” in non-living elastic inclusions) and the non-linear diffusion of the signaling molecules, here termed mechanogens. We suggest model experiments on cell assemblies on substrates that can test the theory as a prelude to its applicability in embryo development where spatial gradients of morphogens initiate cellular development. PMID:27283037

  5. Mechanobiological induction of long-range contractility by diffusing biomolecules and size scaling in cell assemblies.

    Science.gov (United States)

    Dasbiswas, K; Alster, E; Safran, S A

    2016-01-01

    Mechanobiological studies of cell assemblies have generally focused on cells that are, in principle, identical. Here we predict theoretically the effect on cells in culture of locally introduced biochemical signals that diffuse and locally induce cytoskeletal contractility which is initially small. In steady-state, both the concentration profile of the signaling molecule as well as the contractility profile of the cell assembly are inhomogeneous, with a characteristic length that can be of the order of the system size. The long-range nature of this state originates in the elastic interactions of contractile cells (similar to long-range "macroscopic modes" in non-living elastic inclusions) and the non-linear diffusion of the signaling molecules, here termed mechanogens. We suggest model experiments on cell assemblies on substrates that can test the theory as a prelude to its applicability in embryo development where spatial gradients of morphogens initiate cellular development. PMID:27283037

  6. Mechanobiological induction of long-range contractility by diffusing biomolecules and size scaling in cell assemblies

    Science.gov (United States)

    Dasbiswas, K.; Alster, E.; Safran, S. A.

    2016-06-01

    Mechanobiological studies of cell assemblies have generally focused on cells that are, in principle, identical. Here we predict theoretically the effect on cells in culture of locally introduced biochemical signals that diffuse and locally induce cytoskeletal contractility which is initially small. In steady-state, both the concentration profile of the signaling molecule as well as the contractility profile of the cell assembly are inhomogeneous, with a characteristic length that can be of the order of the system size. The long-range nature of this state originates in the elastic interactions of contractile cells (similar to long-range “macroscopic modes” in non-living elastic inclusions) and the non-linear diffusion of the signaling molecules, here termed mechanogens. We suggest model experiments on cell assemblies on substrates that can test the theory as a prelude to its applicability in embryo development where spatial gradients of morphogens initiate cellular development.

  7. Systematic analysis of embryonic stem cell differentiation in hydrodynamic environments with controlled embryoid body size

    Science.gov (United States)

    Kinney, Melissa A.; Saeed, Rabbia; McDevitt, Todd C.

    2015-01-01

    The sensitivity of stem cells to environmental perturbations has prompted many studies which aim to characterize the influence of mechanical factors on stem cell morphogenesis and differentiation. Hydrodynamic cultures, often employed for large scale bioprocessing applications, impart complex fluid shear and transport profiles, and influence cell fate as a result of changes in media mixing conditions. However, previous studies of hydrodynamic cultures have been limited in their ability to distinguish confounding factors that may affect differentiation, including modulation of embryoid body size in response to changes in the hydrodynamic environment. In this study, we demonstrate the ability to control and maintain embryoid body (EB) size using a combination of forced aggregation formation and rotary orbital suspension culture, in order to assess the impact of hydrodynamic cultures on ESC differentiation, independent of EB size. Size-controlled EBs maintained at different rotary orbital speeds exhibited similar morphological features and gene expression profiles, consistent with ESC differentiation. The similar differentiation of ESCs across a range of hydrodynamic conditions suggests that controlling EB formation and resultant size may be important for scalable bioprocessing applications, in order to standardize EB morphogenesis. However, perturbations in the hydrodynamic environment also led to subtle changes in differentiation toward certain lineages, including temporal modulation of gene expression, as well changes in the relative efficiencies of differentiated phenotypes, thereby highlighting important tissue engineering principles that should be considered for implementation in bioreactor design, as well as for directed ESC differentiation. PMID:22609810

  8. Determining the optimum cell size of digital elevation model for hydrologic application

    Indian Academy of Sciences (India)

    Arabinda Sharma; K N Tiwari; P B S Bhadoria

    2011-08-01

    Scale is one of the most important but unsolved issues in various scientific disciplines that deal with spatial data. The arbitrary choice of grid cell size for contour interpolated digital elevation models (DEM) is one of the major sources of uncertainty in the hydrologic modelling process. In this paper, an attempt was made to identify methods for determining an optimum cell size for a contour interpolated DEM in prior to hydrologic modelling. Twenty-meter interval contour lines were used to generate DEMs of five different resolutions, viz., 30, 45, 60, 75, and 90 m using TOPOGRID algorithm. The obtained DEMs were explored for their intrinsic quality using four different methods, i.e., sink analysis, fractal dimension of derived stream network, entropy measurement and semivariogram modelling. These methods were applied to determine the level artifacts (interpolation error) in DEM surface as well as derived stream network, spatial information content and spatial variability respectively. The results indicated that a 90 m cell size is sufficient to capture the terrain variability for subsequent hydrologic modelling in the study area. The significance of this research work is that it provides methods which DEM users can apply to select an appropriate DEM cell size in prior to detailed hydrologic modelling.

  9. The effects of topographical patterns and sizes on neural stem cell behavior.

    Directory of Open Access Journals (Sweden)

    Lin Qi

    Full Text Available Engineered topographical manipulation, a paralleling approach with conventional biochemical cues, has recently attracted the growing interests in utilizations to control stem cell fate. In this study, effects of topological parameters, pattern and size are emphasized on the proliferation and differentiation of adult neural stem cells (ANSCs. We fabricate micro-scale topographical Si wafers with two different feature sizes. These topographical patterns present linear micro-pattern (LMP, circular micro-pattern (CMP and dot micro-pattern (DMP. The results show that the three topography substrates are suitable for ANSC growth, while they all depress ANSC proliferation when compared to non-patterned substrates (control. Meanwhile, LMP and CMP with two feature sizes can both significantly enhance ANSC differentiation to neurons compared to control. The smaller the feature size is, the better upregulation applies to ANSC for the differentiated neurons. The underlying mechanisms of topography-enhanced neuronal differentiation are further revealed by directing suppression of mitogen-activated protein kinase/extracellular signaling-regulated kinase (MAPK/Erk signaling pathway in ANSC using U0126, known to inhibit the activation of Erk. The statistical results suggest MAPK/Erk pathway is partially involved in topography-induced differentiation. These observations provide a better understanding on the different roles of topographical cues on stem cell behavior, especially on the selective differentiation, and facilitate to advance the field of stem cell therapy.

  10. Mercury induces proliferation and reduces cell size in vascular smooth muscle cells through MAPK, oxidative stress and cyclooxygenase-2 pathways

    International Nuclear Information System (INIS)

    Mercury exposure is known to increase cardiovascular risk but the underlying cellular mechanisms remain undetermined. We analyzed whether chronic exposure to HgCl2 affects vascular structure and the functional properties of vascular smooth muscle cells (VSMC) through oxidative stress/cyclooxygenase-2 dependent pathways. Mesenteric resistance arteries and aortas from Wistar rats treated with HgCl2 (first dose 4.6 mg kg−1, subsequent doses 0.07 mg kg−1 day−1, 30 days) and cultured aortic VSMC stimulated with HgCl2 (0.05–5 μg/ml) were used. Treatment of rats with HgCl2 decreased wall thickness of the resistance and conductance vasculature, increased the number of SMC within the media and decreased SMC nucleus size. In VSMCs, exposure to HgCl2: 1) induced a proliferative response and a reduction in cell size; 2) increased superoxide anion production, NADPH oxidase activity, gene and/or protein levels of the NADPH oxidase subunit NOX-1, the EC- and Mn-superoxide dismutases and cyclooxygenase-2 (COX-2); 3) induced activation of ERK1/2 and p38 MAPK. Both antioxidants and COX-2 inhibitors normalized the proliferative response and the altered cell size induced by HgCl2. Blockade of ERK1/2 and p38 signaling pathways abolished the HgCl2-induced Nox1 and COX-2 expression and normalized the alterations induced by mercury in cell proliferation and size. In conclusion, long exposure of VSMC to low doses of mercury activates MAPK signaling pathways that result in activation of inflammatory proteins such as NADPH oxidase and COX-2 that in turn induce proliferation of VSMC and changes in cell size. These findings offer further evidence that mercury might be considered an environmental risk factor for cardiovascular disease. - Highlights: ► Chronic HgCl2 exposure induces vascular remodeling. ► HgCl2 induces proliferation and decreased cell size in vascular smooth muscle cells. ► HgCl2 induces MAPK activation, oxidative stress and COX-2 expression. ► Inhibition of

  11. Mercury induces proliferation and reduces cell size in vascular smooth muscle cells through MAPK, oxidative stress and cyclooxygenase-2 pathways

    Energy Technology Data Exchange (ETDEWEB)

    Aguado, Andrea; Galán, María; Zhenyukh, Olha; Wiggers, Giulia A.; Roque, Fernanda R. [Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), 28029, Madrid (Spain); Redondo, Santiago [Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, 28040, Madrid (Spain); Peçanha, Franck [Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), 28029, Madrid (Spain); Martín, Angela [Departamento de Bioquímica, Fisiología y Genética Molecular, Universidad Rey Juan Carlos, 28922, Alcorcón (Spain); Fortuño, Ana [Área de Ciencias Cardiovasculares, Centro de Investigación Médica Aplicada, Universidad de Navarra, 31008, Pamplona (Spain); Cachofeiro, Victoria [Departamento de Fisiología, Facultad de Medicina, Universidad Complutense, 28040, Madrid (Spain); Tejerina, Teresa [Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, 28040, Madrid (Spain); Salaices, Mercedes, E-mail: mercedes.salaices@uam.es [Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), 28029, Madrid (Spain); and others

    2013-04-15

    Mercury exposure is known to increase cardiovascular risk but the underlying cellular mechanisms remain undetermined. We analyzed whether chronic exposure to HgCl{sub 2} affects vascular structure and the functional properties of vascular smooth muscle cells (VSMC) through oxidative stress/cyclooxygenase-2 dependent pathways. Mesenteric resistance arteries and aortas from Wistar rats treated with HgCl{sub 2} (first dose 4.6 mg kg{sup −1}, subsequent doses 0.07 mg kg{sup −1} day{sup −1}, 30 days) and cultured aortic VSMC stimulated with HgCl{sub 2} (0.05–5 μg/ml) were used. Treatment of rats with HgCl{sub 2} decreased wall thickness of the resistance and conductance vasculature, increased the number of SMC within the media and decreased SMC nucleus size. In VSMCs, exposure to HgCl{sub 2}: 1) induced a proliferative response and a reduction in cell size; 2) increased superoxide anion production, NADPH oxidase activity, gene and/or protein levels of the NADPH oxidase subunit NOX-1, the EC- and Mn-superoxide dismutases and cyclooxygenase-2 (COX-2); 3) induced activation of ERK1/2 and p38 MAPK. Both antioxidants and COX-2 inhibitors normalized the proliferative response and the altered cell size induced by HgCl{sub 2}. Blockade of ERK1/2 and p38 signaling pathways abolished the HgCl{sub 2}-induced Nox1 and COX-2 expression and normalized the alterations induced by mercury in cell proliferation and size. In conclusion, long exposure of VSMC to low doses of mercury activates MAPK signaling pathways that result in activation of inflammatory proteins such as NADPH oxidase and COX-2 that in turn induce proliferation of VSMC and changes in cell size. These findings offer further evidence that mercury might be considered an environmental risk factor for cardiovascular disease. - Highlights: ► Chronic HgCl{sub 2} exposure induces vascular remodeling. ► HgCl{sub 2} induces proliferation and decreased cell size in vascular smooth muscle cells. ► HgCl{sub 2} induces

  12. Comparison of two methods for short circuit current measurement of large size solar cell

    Science.gov (United States)

    Huang, Xuebo; Quan, Chenggen; Kng, Jerald

    2015-07-01

    The differential spectral responsivity (DSR) measurement and the solar simulator based current to voltage characterisation methods are two accurate methods for measuring the short circuit current, a critical parameter, of a solar cell under standard testing conditions. For the calibration of World Photovoltaic Scale (WPVS) reference solar cell with small size (20 mm x 20 mm), the measurement results using these two methods are agreed well within 1%. But for the calibration of large size (e.g. 156 mm x 156 mm) of solar cell, the measurement results using two methods are not agreed well and their deviation could be more than 10 %. In DSR method, the short circuit current of a solar cell is determined through measuring its relative irradiance spectral responsivity in spectral range from 280 nm to 1200 nm and its absolute irradiance responsivity at wavelength of 650 nm by reference standard photodiodes. As the detective area of large size solar cell (detective area: 156 mm x 156 mm) is much bigger than that of standard photodiodes (detective area: 12.56 mm2), the spatial uniformity of irradiance of modulated monochromatic probe beam on the test solar cell and the standard photodiode is critical for calculation of absolute irradiance responsivity of the test solar cell. The correction for the calculation must be done according to the measured spatial uniformity of probe beam and the detective areas of the test solar cell and standard photodiodes. The experiment showed the correction factor and its uncertainty are smaller if the detective areas difference between the test solar cell and the standard is smaller. Based on this observation, a standard solar cell (detective area: 20 mm x 20 mm) instead of standard photodiodes was used to calibrate absolute irradiance responsivity of the test solar cell (detective area: 156 mm x 156 mm) at wavelength of 650 nm. After such improvement, measurement results using two different methods agree well about 3 % for the large size

  13. Limitations of mRNA amplification from small-size cell samples

    Directory of Open Access Journals (Sweden)

    Myklebost Ola

    2005-10-01

    Full Text Available Abstract Background Global mRNA amplification has become a widely used approach to obtain gene expression profiles from limited material. An important concern is the reliable reflection of the starting material in the results obtained. This is especially important with extremely low quantities of input RNA where stochastic effects due to template dilution may be present. This aspect remains under-documented in the literature, as quantitative measures of data reliability are most often lacking. To address this issue, we examined the sensitivity levels of each transcript in 3 different cell sample sizes. ANOVA analysis was used to estimate the overall effects of reduced input RNA in our experimental design. In order to estimate the validity of decreasing sample sizes, we examined the sensitivity levels of each transcript by applying a novel model-based method, TransCount. Results From expression data, TransCount provided estimates of absolute transcript concentrations in each examined sample. The results from TransCount were used to calculate the Pearson correlation coefficient between transcript concentrations for different sample sizes. The correlations were clearly transcript copy number dependent. A critical level was observed where stochastic fluctuations became significant. The analysis allowed us to pinpoint the gene specific number of transcript templates that defined the limit of reliability with respect to number of cells from that particular source. In the sample amplifying from 1000 cells, transcripts expressed with at least 121 transcripts/cell were statistically reliable and for 250 cells, the limit was 1806 transcripts/cell. Above these thresholds, correlation between our data sets was at acceptable values for reliable interpretation. Conclusion These results imply that the reliability of any amplification experiment must be validated empirically to justify that any gene exists in sufficient quantity in the input material. This

  14. Scaffold pore size modulates in vitro osteogenesis of human adipose-derived stem/stromal cells

    International Nuclear Information System (INIS)

    Trabecular bone has an interconnected porous structure, which influences cellular responses, biochemical transport and mechanical strength. Appropriately mimicking this structural organization in biomaterial scaffolds can facilitate more robust bone tissue regeneration and integration by providing a native microenvironment to the cells. This study examined the effect of pore size on human adipose-derived stem/stromal cell (ASC) osteogenesis within poly(ε-caprolactone) (PCL) scaffolds. Scaffold pore size was controlled by porogen leaching of custom-made paraffin particles with three different size ranges: P200 (< 500 µm), P500 (500–1000 µm), and P1000 (1000–1500 µm). Scaffolds produced by leaching these particles exhibited highly interconnected pores and rough surface structures that were favorable for cell attachment and ingrowth. The osteogenic response of ASCs was evaluated following 3 weeks of in vitro culture using biochemical (ALP, Ca2+/DNA content), mechanical (compression test) and histological (H and E and von Kossa staining) analyses. It was observed that while the total number of cells was similar for all scaffolds, the cell distributions and osteogenic properties were affected by the scaffold pore size. ASCs were able to bridge smaller pores and grow uniformly within these scaffolds (P200) while they grew as a layer along the periphery of the largest pores (P1000). The cell-biomaterial interactions specific to the latter case led to enhanced osteogenic responses. The ALP activity and Ca2+ deposition were doubled in P1000 scaffolds as compared to P200 scaffolds. A significant difference was observed between the compressive strength of unseeded and seeded P1000 scaffolds. Therefore, we demonstrated that the use of scaffolds with pores that are in the range of 1 mm enhances in vitro ASC osteogenesis, which may improve their performance in engineered bone substitutes. (paper)

  15. The Influences of Cell Type and ZnO Nanoparticle Size on Immune Cell Cytotoxicity and Cytokine Induction

    Directory of Open Access Journals (Sweden)

    Thurber Aaron

    2009-01-01

    Full Text Available Abstract Nanotechnology represents a new and enabling platform that promises to provide a range of innovative technologies for biological applications. ZnO nanoparticles of controlled size were synthesized, and their cytotoxicity toward different human immune cells evaluated. A differential cytotoxic response between human immune cell subsets was observed, with lymphocytes being the most resistant and monocytes being the most susceptible to ZnO nanoparticle-induced toxicity. Significant differences were also observed between previously activated memory lymphocytes and naive lymphocytes, indicating a relationship between cell-cycle potential and nanoparticle susceptibility. Mechanisms of toxicity involve the generation of reactive oxygen species, with monocytes displaying the highest levels, and the degree of cytotoxicity dependent on the extent of nanoparticle interactions with cellular membranes. An inverse relationship between nanoparticle size and cytotoxicity, as well as nanoparticle size and reactive oxygen species production was observed. In addition, ZnO nanoparticles induce the production of the proinflammatory cytokines, IFN-γ, TNF-α, and IL-12, at concentrations below those causing appreciable cell death. Collectively, these results underscore the need for careful evaluation of ZnO nanoparticle effects across a spectrum of relevant cell types when considering their use for potential new nanotechnology-based biological applications.

  16. Fusion Pore Size Limits 5-HT Release From Single Enterochromaffin Cell Vesicles.

    Science.gov (United States)

    Raghupathi, Ravinarayan; Jessup, Claire F; Lumsden, Amanda L; Keating, Damien J

    2016-07-01

    Enterochromaffin cells are the major site of serotonin (5-HT) synthesis and secretion providing ∼95% of the body's total 5-HT. 5-HT can act as a neurotransmitter or hormone and has several important endocrine and paracrine roles. We have previously demonstrated that EC cells release small amounts of 5-HT per exocytosis event compared to other endocrine cells. We utilized a recently developed method to purify EC cells to demonstrate the mechanisms underlying 5-HT packaging and release. Using the fluorescent probe FFN511, we demonstrate that EC cells express VMAT and that VMAT plays a functional role in 5-HT loading into vesicles. Carbon fiber amperometry studies illustrate that the amount of 5-HT released per exocytosis event from EC cells is dependent on both VMAT and the H(+)-ATPase pump, as demonstrated with reserpine or bafilomycin, respectively. We also demonstrate that increasing the amount of 5-HT loaded into EC cell vesicles does not result in an increase in quantal release. As this indicates that fusion pore size may be a limiting factor involved, we compared pore diameter in EC and chromaffin cells by assessing the vesicle capture of different-sized fluorescent probes to measure the extent of fusion pore dilation. This identified that EC cells have a reduced fusion pore expansion that does not exceed 9 nm in diameter. These results demonstrate that the small amounts of 5-HT released per fusion event in EC cells can be explained by a smaller fusion pore that limits 5-HT release capacity from individual vesicles. PMID:26574734

  17. Gold nanoparticle size and shape influence on osteogenesis of mesenchymal stem cells

    Science.gov (United States)

    Li, Jingchao; Li, Jia'en Jasmine; Zhang, Jing; Wang, Xinlong; Kawazoe, Naoki; Chen, Guoping

    2016-04-01

    Gold nanoparticles (AuNPs) have been extensively explored for biomedical applications due to their advantages of facile synthesis and surface functionalization. Previous studies have suggested that AuNPs can induce differentiation of stem cells into osteoblasts. However, how the size and shape of AuNPs affect the differentiation response of stem cells has not been elucidated. In this work, a series of bovine serum albumin (BSA)-coated Au nanospheres, Au nanostars and Au nanorods with different diameters of 40, 70 and 110 nm were synthesized and their effects on osteogenic differentiation of human mesenchymal stem cells (hMSCs) were investigated. All the AuNPs showed good cytocompatibility and did not influence proliferation of hMSCs at the studied concentrations. Osteogenic differentiation of hMSCs was dependent on the size and shape of AuNPs. Sphere-40, sphere-70 and rod-70 significantly increased the alkaline phosphatase (ALP) activity and calcium deposition of cells while rod-40 reduced the ALP activity and calcium deposition. Gene profiling revealed that the expression of osteogenic marker genes was down-regulated after incubation with rod-40. However, up-regulation of these genes was found in the sphere-40, sphere-70 and rod-70 treatment. Moreover, it was found that the size and shape of AuNPs affected the osteogenic differentiation of hMSCs through regulating the activation of Yes-associated protein (YAP). These results indicate that the size and shape of AuNPs had an influence on the osteogenic differentiation of hMSCs, which should provide useful guidance for the preparation of AuNPs with defined size and shape for their biomedical applications.Gold nanoparticles (AuNPs) have been extensively explored for biomedical applications due to their advantages of facile synthesis and surface functionalization. Previous studies have suggested that AuNPs can induce differentiation of stem cells into osteoblasts. However, how the size and shape of AuNPs affect the

  18. Molecular behavior of DNA in a cell-sized compartment coated by lipids

    CERN Document Server

    Hamada, T; Shimobayashi, S F; Ichikawa, M; Takagi, M

    2015-01-01

    The behavior of long DNA molecules in a cell-sized confined space was investigated. We prepared water-in-oil droplets covered by phospholipids, which mimic the inner space of a cell, following the encapsulation of DNA molecules with unfolded coil and folded globule conformations. Microscopic observation revealed that the adsorption of coiled DNA onto the membrane surface depended on the size of the vesicular space. Globular DNA showed a cell-size-dependent unfolding transition after adsorption on the membrane. Furthermore, when DNA interacted with a two-phase membrane surface, DNA selectively adsorbed on the membrane phase, such as an ordered or disordered phase, depending on its conformation. We discuss the mechanism of these trends by considering the free energy of DNA together with a polyamine in the solution. The free energy of our model was consistent with the present experimental data. The cooperative interaction of DNA and polyamines with a membrane surface leads to the size-dependent behavior of molec...

  19. Particle Size Affects Concentration-Dependent Cytotoxicity of Chitosan Nanoparticles towards Mouse Hematopoietic Stem Cells

    Directory of Open Access Journals (Sweden)

    Siti Sarah Omar Zaki

    2015-01-01

    Full Text Available Chitosan nanoparticles (CSNPs have been extensively applied in medical and pharmaceutical fields as promising drug delivery systems. Despite that, the safety of CSNPs remains inadequate and needs further investigation, particularly on hematopoietic stem cells (HSCs. CSNPs were prepared by ionic gelation method and later were characterized for their physical characteristics (particle size and zeta potential. Cytotoxicity of CSNPs was assessed by MTT assay. Particle size was highly influenced by chitosan concentration and molecular weight (medium and high molecular weight (MMW and HMW. Higher chitosan concentration and molecular weight produced larger nanoparticles. Zeta potential of CSNPs was not significantly affected by chitosan concentrations and molecular weights used in the present study. MMW had a better stability than HMW CSNPs as their particle size and zeta potential were not significantly altered after autoclaving. Cytotoxicity of CSNPs was influenced by zeta potential and particle size. On the other hand, chitosan concentration and molecular weight indirectly influenced cytotoxicity by affecting particle size and zeta potential of CSNPs. In conclusion, cytotoxicity of CSNPs was mainly attributed to their physical characteristics and this opens a strategy to ensure the safety of CSNPs applications in stem cell technology.

  20. Heterotrophic free-living and particle-bound bacterial cell size in the river Cauvery and its downstream tributaries

    Indian Academy of Sciences (India)

    T S Harsha; Sadanand M Yamakanamardi; M Mahadevaswamy

    2007-03-01

    This is the first comprehensive study on planktonic heterotrophic bacterial cell size in the river Cauvery and its important tributaries in Karnataka State, India. The initial hypothesis that the mean cell size of planktonic heterotrophic bacteria in the four tributaries are markedly different from each other and also from that in the main river Cauvery was rejected, because all five watercourses showed similar planktonic heterotrophic bacterial cell size. Examination of the correlation between mean heterotrophic bacterial cell size and environmental variables showed four correlations in the river Arkavathy and two in the river Shimsha. Regression analysis revealed that 18% of the variation in mean heterotrophic free-living bacterial cell size was due to biological oxygen demand (BOD) in the river Arkavathy, 11% due to surface water velocity (SWV) in the river Cauvery and 11% due to temperature in the river Kapila. Heterotrophic particle-bound bacterial cell size variation was 28% due to chloride and BOD in the river Arkavathy, 11% due to conductivity in the river Kapila and 8% due to calcium in the river Cauvery. This type of relationship between heterotrophic bacterial cell size and environmental variables suggests that, though the mean heterotrophic bacterial cell size was similar in all the five water courses, different sets of environmental variables apparently control the heterotrophic bacterial cell size in the various water bodies studied in this investigation. The possible cause for this environmental (bottom–up) control is discussed.

  1. Size-dependence of volatile and semi-volatile organic carbon content in phytoplankton cells

    Directory of Open Access Journals (Sweden)

    Sergio eRuiz-Halpern

    2014-07-01

    Full Text Available The content of volatile and semivolatile organic compounds (VOC and SOC, measured as exchangeable dissolved organic carbon (EDOC, was quantified in 9 phytoplanktonic species that spanned 4 orders of magnitude in cell volume, by disrupting the cells and quantifying the gaseous organic carbon released. EDOC content varied 4 orders of magnitude, from 0.0015 to 14.12 pg C cell-1 in the species studied and increased linearly with increasing phytoplankton cell volume following the equation EDOC (pg C cell-1 = -2.35 x cellular volume (CV, µm3 cell-1 0.90 (± 0.3, with a slope (0.90 not different from 1 indicating a constant increase in volatile carbon as the cell size of phytoplankton increased. The percentage of EDOC relative to total cellular carbon was small but varied 20 fold from 0.28 % to 5.17 %, and no obvious taxonomic pattern in the content of EDOC was appreciable for the species tested. The cell release rate of EDOC is small compared to the amount of carbon in the cell and difficult to capture. Nonetheless, the results point to a potential flux of volatile and semivolatile phytoplankton-derived organic carbon to the atmosphere that has been largely underestimated and deserves further attention in the future.

  2. Determination of the pore size of cell walls of living plant cells

    Energy Technology Data Exchange (ETDEWEB)

    Carpita, N.; Sabularse, D.; Montezinos, D.; Delmer, D.P.

    1979-09-14

    The limiting diameter of pores in the walls of living plant cells through which molecules can freely pass has been determined by a solute exclusion technique to be 35 to 38 angstroms for hair cells of Raphanus sativus roots and fibers of Gossypium hirsutum, 38 to 40 angstroms for cultured cells of Acer pseudoplatanus, and 45 to 52 angstroms for isolated palisade parenchyma cells of the leaves of Xanthium strumarium and Commelina communis. These results indicate that molecules with diameters larger than these pores would be restricted in their ability to penetrate such a cell wall, and that such a wall may represent a more significant barrier to cellular communication than has been previously assumed.

  3. Optimization and Evaluation of a Novel Size Based Circulating Tumor Cell Isolation System.

    Science.gov (United States)

    Xu, Lei; Mao, Xueying; Imrali, Ahmet; Syed, Ferrial; Mutsvangwa, Katherine; Berney, Daniel; Cathcart, Paul; Hines, John; Shamash, Jonathan; Lu, Yong-Jie

    2015-01-01

    Isolation of circulating tumor cells (CTCs) from peripheral blood has the potential to provide a far easier "liquid biopsy" than tumor tissue biopsies, to monitor tumor cell populations during disease progression and in response to therapies. Many CTC isolation technologies have been developed. We optimized the Parsortix system, an epitope independent, size and compressibility-based platform for CTCs isolation, making it possible to harvest CTCs at the speed and sample volume comparable to standard CellSearch system. We captured more than half of cancer cells from different cancer cell lines spiked in blood samples from healthy donors using this system. Cell loss during immunostaining of cells transferred and fixed on the slides is a major problem for analyzing rare cell samples. We developed a novel cell transfer and fixation method to retain >90% of cells on the slide after the immunofluorescence process without affecting signal strength and specificity. Using this optimized method, we evaluated the Parsortix system for CTC harvest in prostate cancer patients in comparison to immunobead based CTC isolation systems IsoFlux and CellSearch. We harvested a similar number (p = 0.33) of cytokeratin (CK) positive CTCs using Parsortix and IsoFlux from 7.5 mL blood samples of 10 prostate cancer patients (an average of 33.8 and 37.6 respectively). The purity of the CTCs harvested by Parsortix at 3.1% was significantly higher than IsoFlux at 1.0% (p = 0.02). Parsortix harvested significantly more CK positive CTCs than CellSearch (p = 0.04) in seven prostate cancer patient samples, where both systems were utilized (an average of 32.1 and 10.1 respectively). We also captured CTC clusters using Parsortix. Using four-color immunofluorescence we found that 85.8% of PC3 cells expressed EpCAM, 91.7% expressed CK and 2.5% cells lacked both epithelial markers. Interestingly, 95.6% of PC3 cells expressed Vimentin, including those cells that lacked both epithelial marker expression

  4. Optimization and Evaluation of a Novel Size Based Circulating Tumor Cell Isolation System.

    Directory of Open Access Journals (Sweden)

    Lei Xu

    Full Text Available Isolation of circulating tumor cells (CTCs from peripheral blood has the potential to provide a far easier "liquid biopsy" than tumor tissue biopsies, to monitor tumor cell populations during disease progression and in response to therapies. Many CTC isolation technologies have been developed. We optimized the Parsortix system, an epitope independent, size and compressibility-based platform for CTCs isolation, making it possible to harvest CTCs at the speed and sample volume comparable to standard CellSearch system. We captured more than half of cancer cells from different cancer cell lines spiked in blood samples from healthy donors using this system. Cell loss during immunostaining of cells transferred and fixed on the slides is a major problem for analyzing rare cell samples. We developed a novel cell transfer and fixation method to retain >90% of cells on the slide after the immunofluorescence process without affecting signal strength and specificity. Using this optimized method, we evaluated the Parsortix system for CTC harvest in prostate cancer patients in comparison to immunobead based CTC isolation systems IsoFlux and CellSearch. We harvested a similar number (p = 0.33 of cytokeratin (CK positive CTCs using Parsortix and IsoFlux from 7.5 mL blood samples of 10 prostate cancer patients (an average of 33.8 and 37.6 respectively. The purity of the CTCs harvested by Parsortix at 3.1% was significantly higher than IsoFlux at 1.0% (p = 0.02. Parsortix harvested significantly more CK positive CTCs than CellSearch (p = 0.04 in seven prostate cancer patient samples, where both systems were utilized (an average of 32.1 and 10.1 respectively. We also captured CTC clusters using Parsortix. Using four-color immunofluorescence we found that 85.8% of PC3 cells expressed EpCAM, 91.7% expressed CK and 2.5% cells lacked both epithelial markers. Interestingly, 95.6% of PC3 cells expressed Vimentin, including those cells that lacked both epithelial marker

  5. Antagonistic control of muscle cell size by AMPK and mTORC1.

    Science.gov (United States)

    Mounier, Rémi; Lantier, Louise; Leclerc, Jocelyne; Sotiropoulos, Athanassia; Foretz, Marc; Viollet, Benoit

    2011-08-15

    Nutrition and physical activity have profound effects on skeletal muscle metabolism and growth. Regulation of muscle mass depends on a thin balance between growth-promoting and growth-suppressing factors. Over the past decade, the mammalian target of rapamycin (mTOR) kinase has emerged as an essential factor for muscle growth by mediating the anabolic response to nutrients, insulin, insulin-like growth factors and resistance exercise. As opposed to the mTOR signaling pathway, the AMP-activated protein kinase (AMPK) is switched on during starvation and endurance exercise to upregulate energy-conserving processes. Recent evidence indicates that mTORC1 (mTOR Complex 1) and AMPK represent two antagonistic forces governing muscle adaption to nutrition, starvation and growth stimulation. Animal knockout models with impaired mTORC1 signaling showed decreased muscle mass correlated with increased AMPK activation. Interestingly, AMPK inhibition in p70S6K-deficient muscle cells restores cell growth and sensitivity to nutrients. Conversely, muscle cells lacking AMPK have increased mTORC1 activation with increased cell size and protein synthesis rate. We also demonstrated that the hypertrophic action of MyrAkt is enhanced in AMPK-deficient muscle, indicating that AMPK acts as a negative feedback control to restrain muscle hypertrophy. Our recent results extend this notion by showing that AMPKα1, but not AMPKα2, regulates muscle cell size through the control of mTORC1 signaling. These results reveal the diverse functions of the two catalytic isoforms of AMPK, with AMPKα1 playing a predominant role in the control of muscle cell size and AMPKα2 mediating muscle metabolic adaptation. Thus, the crosstalk between AMPK and mTORC1 signaling is a highly regulated way to control changes in muscle growth and metabolic rate imposed by external cues. PMID:21799304

  6. Molecular control of brain size: Regulators of neural stem cell life, death and beyond

    International Nuclear Information System (INIS)

    The proper development of the brain and other organs depends on multiple parameters, including strictly controlled expansion of specific progenitor pools. The regulation of such expansion events includes enzymatic activities that govern the correct number of specific cells to be generated via an orchestrated control of cell proliferation, cell cycle exit, differentiation, cell death etc. Certain proteins in turn exert direct control of these enzymatic activities and thus progenitor pool expansion and organ size. The members of the Cip/Kip family (p21Cip1/p27Kip1/p57Kip2) are well-known regulators of cell cycle exit that interact with and inhibit the activity of cyclin-CDK complexes, whereas members of the p53/p63/p73 family are traditionally associated with regulation of cell death. It has however become clear that the roles for these proteins are not as clear-cut as initially thought. In this review, we discuss the roles for proteins of the Cip/Kip and p53/p63/p73 families in the regulation of cell cycle control, differentiation, and death of neural stem cells. We suggest that these proteins act as molecular interfaces, or 'pilots', to assure the correct assembly of protein complexes with enzymatic activities at the right place at the right time, thereby regulating essential decisions in multiple cellular events.

  7. Continuous medium exchange and cell isolation by size-selective passage through slanted micro-obstacles

    International Nuclear Information System (INIS)

    The ability to isolate cells from contaminant particles such as cellular debris and simultaneously exchange the carrier medium of the cells is important for obtaining experimental integrity and optimal cell health. Although microfluidic manipulation techniques have demonstrated their ability to exchange the carrier medium of cells, they still require large device footprint (typically several cm2) that makes it difficult for them to be integrated into microfluidic systems. Here, we report a microfluidic device that overcomes the limitation by utilizing size-selective passage through slanted obstacles. A gap formed underneath the obstacles allows passage of small contaminant particles, while directing larger cells along the periphery of the obstacles. We demonstrated the utility of our device in a small device footprint of 0.05 mm2 for efficient exchange of the carrier medium of mammalian cells, and achieved isolation of the cells from 1 µm diameter contaminant particles in 4.4 ms with an enrichment factor of 834, an isolation purity of ≈70%, and a throughput of 465 cells min−1. (paper)

  8. Analysis of a Stochastic Model for Bacterial Growth and the Lognormality of the Cell-Size Distribution

    Science.gov (United States)

    Yamamoto, Ken; Wakita, Jun-ichi

    2016-07-01

    This paper theoretically analyzes a phenomenological stochastic model for bacterial growth. This model comprises cell division and the linear growth of cells, where growth rates and cell cycles are drawn from lognormal distributions. We find that the cell size is expressed as a sum of independent lognormal variables. We show numerically that the quality of the lognormal approximation greatly depends on the distributions of the growth rate and cell cycle. Furthermore, we show that actual parameters of the growth rate and cell cycle take values that give a good lognormal approximation; thus, the experimental cell-size distribution is in good agreement with a lognormal distribution.

  9. Analysis of a stochastic model for bacterial growth and the lognormality in the cell-size distribution

    CERN Document Server

    Yamamoto, Ken

    2016-01-01

    This paper theoretically analyzes a phenomenological stochastic model for bacterial growth. This model comprises cell divisions and linear growth of cells, where growth rates and cell cycles are drawn from lognormal distributions. We derive that the cell size is expressed as a sum of independent lognormal variables. We show numerically that the quality of the lognormal approximation greatly depends on the distributions of the growth rate and cell cycle. Furthermore, we show that actual parameters of the growth rate and cell cycle take values which give good lognormal approximation, so the experimental cell-size distribution is in good agreement with a lognormal distribution.

  10. Transporting of a Cell-Sized Phospholipid Vesicle Across Water/Oil Interface

    CERN Document Server

    Hase, M; Hamada, T; Yoshikawa, K; Hase, Masahiko; Yamada, Ayako; Hamada, Tsutomu; Yoshikawa, Kenichi

    2006-01-01

    When a cell-sized water droplet, with a diameter of several tens of micro meter, is placed in oil containing phospholipids, a stable cell-sized vesicle is spontaneously formed as a water-in-oil phospholipid emulsion (W/O CE) with a phospholipid monolayer. We transferred the lipid vesicle thus formed in the oil phase to the water phase across the water/oil interface by micromanipulation, which suggests that the vesicle is transformed from a phospholipid monolayer as W/O CE into a bilayer. The lipid vesicle can then be transported back into the oil phase. This novel experimental procedure may be a useful tool for creating a model cellular system, which, together with a microreactor, is applicable as a micrometer-scale biochemical reaction field.

  11. Toxicity of nano- and micro-sized ZnO particles in human lung epithelial cells

    International Nuclear Information System (INIS)

    This is the first comprehensive study to evaluate the cytotoxicity, biochemical mechanisms of toxicity, and oxidative DNA damage caused by exposing human bronchoalveolar carcinoma-derived cells (A549) to 70 and 420 nm ZnO particles. Particles of either size significantly reduced cell viability in a dose- and time-dependent manner within a rather narrow dosage range. Particle mass-based dosimetry and particle-specific surface area-based dosimetry yielded two distinct patterns of cytotoxicity in both 70 and 420 nm ZnO particles. Elevated levels of reactive oxygen species (ROS) resulted in intracellular oxidative stress, lipid peroxidation, cell membrane leakage, and oxidative DNA damage. The protective effect of N-acetylcysteine on ZnO-induced cytotoxicity further implicated oxidative stress in the cytotoxicity. Free Zn2+ and metal impurities were not major contributors of ROS induction as indicated by limited free Zn2+ cytotoxicity, extent of Zn2+ dissociation in the cell culture medium, and inductively-coupled plasma-mass spectrometry metal analysis. We conclude that (1) exposure to both sizes of ZnO particles leads to dose- and time-dependent cytotoxicity reflected in oxidative stress, lipid peroxidation, cell membrane damage, and oxidative DNA damage, (2) ZnO particles exhibit a much steeper dose-response pattern unseen in other metal oxides, and (3) neither free Zn2+ nor metal impurity in the ZnO particle samples is the cause of cytotoxicity.

  12. Tuning the Properties of Polymer Bulk Heterojunction Solar Cells by Adjusting Fullerene Size to Control Intercalation

    KAUST Repository

    Cates, Nichole C.

    2009-12-09

    We demonstrate that intercalation of fullerene derivatives between the side chains of conjugated polymers can be controlled by adjusting the fullerene size and compare the properties of intercalated and nonintercalated poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT):fullerene blends. The intercalated blends, which exhibit optimal solar-cell performance at 1:4 polymer:fullerene by weight, have better photoluminescence quenching and lower absorption than the nonintercalated blends, which optimize at 1:1. Understanding how intercalation affects performance will enable more effective design of polymer:fullerene solar cells. © 2009 American Chemical Society.

  13. Finite element analysis of micropipette aspiration considering finite size and compressibility of cells

    Science.gov (United States)

    Li, YongSheng; Chen, WeiYi

    2013-11-01

    Micropipette aspiration (MA) is widely applied in cell mechanics, however, at small deformations a common model corresponding to the MA is the half-space model wherein the finite cell size and cell compressibility are neglected. This study extends the half-space model by accounting for the influence of cell geometry and compressibility (sphere model). Using a finite element analysis of cell aspiration into a micropipette, an elastic approximation formula of the aspirated length was derived for the sphere model. The approximation formula includes the geometry parameter ξ of the sphere model ( ξ= R/ a, R is the radius of the cell, and a is the inner radius of the micropipette) and the Poisson's ratio v of the cell. The results indicate that the parameter ξ and Poisson's ratio v markedly affect the aspirated length, particularly for small ξ and v. When ξ→∞ and v→0.5, the approximation formula tends to the analytical solution for the half-space model. In the incompressible case ( v = 0.5), within the general experimental range ( ξ varying from 2 to 4), the difference between the analytical solution and the approximate one is significant, and is up to 29% of the approximation solution when ξ = 2. Additionally, parametere was introduced to evaluate the error of elastic moduli between the half-space model and sphere model. Based on the approximation formula, the ξ thresholds, beyond which e becomes larger than 10% and 20%, were derived.

  14. Experimental study of commercial size proton exchange membrane fuel cell performance

    International Nuclear Information System (INIS)

    Commercial sized (16 x 16 cm2 active surface area) proton exchange membrane (PEM) fuel cells with serpentine flow chambers are fabricated. The GORE-TEX (registered) PRIMEA 5621 was used with a 35-μm-thick PEM with an anode catalyst layer with 0.45 mg cm-2 Pt and cathode catalyst layer with 0.6 mg cm-2 Pt and Ru or GORE-TEX (registered) PRIMEA 57 was used with an 18-μm-thick PEM with an anode catalyst layer at 0.2 mg cm-2 Pt and cathode catalyst layer at 0.4 mg cm-2 of Pt and Ru. At the specified cell and humidification temperatures, the thin PRIMEA 57 membrane yields better cell performance than the thick PRIMEA 5621 membrane, since hydration of the former is more easily maintained with the limited amount of produced water. Sufficient humidification at both the cathode and anode sides is essential to achieve high cell performance with a thick membrane, like the PRIMEA 5621. The optimal cell temperature to produce the best cell performance with PRIMEA 5621 is close to the humidification temperature. For PRIMEA 57, however, optimal cell temperature exceeds the humidification temperature.

  15. Size-dependent cytotoxicity of europium doped NaYF{sub 4} nanoparticles in endothelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shizhu; Zhang, Cuimiao; Jia, Guang; Duan, Jianlei; Wang, Shuxiang, E-mail: wsx@hbu.edu.cn; Zhang, Jinchao, E-mail: jczhang6970@163.com

    2014-10-01

    Lanthanide-doped sodium yttrium fluoride (NaYF{sub 4}) nanoparticles exhibit novel optical properties which make them be widely used in various fields. The extensive applications increase the chance of human exposure to these nanoparticles and thus raise deep concerns regarding their riskiness. In the present study, we have synthesized europium doped NaYF{sub 4} (NaYF{sub 4}:Eu{sup 3+}) nanoparticles with three diameters and used endothelial cells (ECs) as a cell model to explore the potential toxic effect. The cell viability, cytomembrane integrity, cellular uptake, intracellular localization, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), apoptosis detection, caspase-3 activity and expression of inflammatory gene were studied. The results indicated that these nanoparticles could be uptaken into ECs and decrease the cell viability, induce the intracellular lactate dehydrogenase (LDH) release, increase the ROS level, and decrease the cell MMP in a size-dependent manner. Besides that, the cells were suffered to apoptosis with the caspase-3 activation, and the inflammation specific gene expressions (ICAM1 and VCAM1) were also increased. Our results suggest that the damage pathway may be related to the ROS generation and mitochondrial damage. The results provide novel evidence to elucidate their toxicity mechanisms and may be helpful for more rational applications of these compounds in the future. - Highlights: • NaYF{sub 4}:Eu{sup 3+} nanoparticles with three diameters have been synthesized. • NaYF{sub 4}:Eu{sup 3+} nanoparticles could be uptaken by endothelial cells (ECs). • NaYF{sub 4}:Eu{sup 3+} nanoparticles show a significant cytotoxicity on ECs. • The size of NaYF{sub 4}:Eu{sup 3+} nanoparticles may be important to their toxicology effect.

  16. Replicon sizes in non-transformed and SV40-transformed cells, as estimated by a bromodeoxyuridine photolysis method

    International Nuclear Information System (INIS)

    Replicon sizes were measured in Simian Virus 40 (SV40)-transformed and untransformed normal human, xeroderma pigmentosum (XP), and mouse 3T3 cells with an x-ray plus bromodeoxyuridine (BUdR) photolysis method. Replicon sizes in SV40-transformed cells were at least twice those in untransformed counterparts, but DNA fork displacement rates were only slightly increased

  17. Cell size distribution in a random tessellation of space governed by the Kolmogorov-Johnson-Mehl-Avrami model: Grain size distribution in crystallization

    OpenAIRE

    Farjas Silva, Jordi; Roura Grabulosa, Pere

    2008-01-01

    The space subdivision in cells resulting from a process of random nucleation and growth is a subject of interest in many scientific fields. In this paper, we deduce the expected value and variance of these distributions while assuming that the space subdivision process is in accordance with the premises of the Kolmogorov-Johnson-Mehl-Avrami model. We have not imposed restrictions on the time dependency of nucleation and growth rates. We have also developed an approximate analytical cell size ...

  18. Effects of meal size and composition on incretin, alpha-cell, and beta-cell responses

    DEFF Research Database (Denmark)

    Rijkelijkhuizen, Josina M; McQuarrie, Kelly; Girman, Cynthia J;

    2009-01-01

    The incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) regulate postprandial insulin release from the beta-cells. We investigated the effects of 3 standardized meals with different caloric and nutritional content in terms of postprandial glucose, insu...

  19. Support for the initial attachment, growth and differentiation of MG-63 cells: a comparison between nano-size hydroxyapatite and micro-size hydroxyapatite in composites

    Directory of Open Access Journals (Sweden)

    Filová E

    2014-08-01

    Full Text Available Elena Filová,1 Tomáš Suchý,2,3 Zbynek Sucharda,2 Monika Šupová,2 Margit Žaloudková,2 Karel Balík,2 Vera Lisá,1 Miroslav Šlouf,4 Lucie Bacáková11Department of Biomaterials and Tissue Engineering, Institute of Physiology, 2Department of Composite and Carbon Materials, Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, 3Laboratory of Biomechanics, Department of Mechanics, Biomechanics and Mechatronics, Faculty of Mechanical Engineering, CTU in Prague, 4Department of Morphology and Rheology of Polymer Materials, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech RepublicAbstract: Hydroxyapatite (HA is considered to be a bioactive material that favorably influences the adhesion, growth, and osteogenic differentiation of osteoblasts. To optimize the cell response on the hydroxyapatite composite, it is desirable to assess the optimum concentration and also the optimum particle size. The aim of our study was to prepare composite materials made of polydimethylsiloxane, polyamide, and nano-sized (N or micro-sized (M HA, with an HA content of 0%, 2%, 5%, 10%, 15%, 20%, 25% (v/v (referred to as N0–N25 or M0–M25, and to evaluate them in vitro in cultures with human osteoblast-like MG-63 cells. For clinical applications, fast osseointegration of the implant into the bone is essential. We observed the greatest initial cell adhesion on composites M10 and N5. Nano-sized HA supported cell growth, especially during the first 3 days of culture. On composites with micro-size HA (2%–15%, MG-63 cells reached the highest densities on day 7. Samples M20 and M25, however, were toxic for MG-63 cells, although these composites supported the production of osteocalcin in these cells. On N2, a higher concentration of osteopontin was found in MG-63 cells. For biomedical applications, the concentration range of 5%–15% (v/v nano-size or micro-size HA seems to be optimum

  20. Ecological effects of cell-level processes: genome size, functional traits and regional abundance of herbaceous plant species

    Science.gov (United States)

    Herben, Tomáš; Suda, Jan; Klimešová, Jitka; Mihulka, Stanislav; Říha, Pavel; Šímová, Irena

    2012-01-01

    Background and Aims Genome size is known to be correlated with a number of phenotypic traits associated with cell sizes and cell-division rates. Genome size was therefore used as a proxy for them in order to assess how common plant traits such as height, specific leaf area and seed size/number predict species regional abundance. In this study it is hypothesized that if there is residual correlation between genome size and abundance after these traits are partialled out, there must be additional ecological effects of cell size and/or cell-division rate. Methods Variation in genome size, plant traits and regional abundance were examined in 436 herbaceous species of central European flora, and relationships were sought for among these variables by correlation and path analysis. Key Results Species regional abundance was weakly but significantly correlated with genome size; the relationship was stronger for annuals (R2 = 0·145) than for perennials (R2 = 0·027). In annuals, genome size was linked to abundance via its effect on seed size, which constrains seed number and hence population growth rate. In perennials, it weakly affected (via height and specific leaf area) competitive ability. These relationships did not change qualitatively after phylogenetic correction. In both annuals and perennials there was an unresolved effect of genome size on abundance. Conclusions The findings indicate that additional predictors of regional abundance should be sought among variables that are linked to cell size and cell-division rate. Signals of these cell-level processes remain identifiable even at the landscape scale, and show deep differences between perennials and annuals. Plant population biology could thus possibly benefit from more systematic use of indicators of cell-level processes. PMID:22628380

  1. Assessing T cell clonal size distribution: a non-parametric approach.

    Science.gov (United States)

    Bolkhovskaya, Olesya V; Zorin, Daniil Yu; Ivanchenko, Mikhail V

    2014-01-01

    Clonal structure of the human peripheral T-cell repertoire is shaped by a number of homeostatic mechanisms, including antigen presentation, cytokine and cell regulation. Its accurate tuning leads to a remarkable ability to combat pathogens in all their variety, while systemic failures may lead to severe consequences like autoimmune diseases. Here we develop and make use of a non-parametric statistical approach to assess T cell clonal size distributions from recent next generation sequencing data. For 41 healthy individuals and a patient with ankylosing spondylitis, who undergone treatment, we invariably find power law scaling over several decades and for the first time calculate quantitatively meaningful values of decay exponent. It has proved to be much the same among healthy donors, significantly different for an autoimmune patient before the therapy, and converging towards a typical value afterwards. We discuss implications of the findings for theoretical understanding and mathematical modeling of adaptive immunity. PMID:25275470

  2. Assessing T cell clonal size distribution: a non-parametric approach.

    Directory of Open Access Journals (Sweden)

    Olesya V Bolkhovskaya

    Full Text Available Clonal structure of the human peripheral T-cell repertoire is shaped by a number of homeostatic mechanisms, including antigen presentation, cytokine and cell regulation. Its accurate tuning leads to a remarkable ability to combat pathogens in all their variety, while systemic failures may lead to severe consequences like autoimmune diseases. Here we develop and make use of a non-parametric statistical approach to assess T cell clonal size distributions from recent next generation sequencing data. For 41 healthy individuals and a patient with ankylosing spondylitis, who undergone treatment, we invariably find power law scaling over several decades and for the first time calculate quantitatively meaningful values of decay exponent. It has proved to be much the same among healthy donors, significantly different for an autoimmune patient before the therapy, and converging towards a typical value afterwards. We discuss implications of the findings for theoretical understanding and mathematical modeling of adaptive immunity.

  3. Selective Rapid Eye Movement Sleep Deprivation Affects Cell Size and Number in Kitten Locus Coeruleus

    Directory of Open Access Journals (Sweden)

    James P Shaffery

    2012-05-01

    Full Text Available Cells in the locus coeruleus (LC constitute the sole source of norepinephrine (NE in the brain, and change their discharge rates according to vigilance state. In addition to its well established role in vigilance, NE affects synaptic plasticity in the postnatal critical period (CP of development. One form of CP synaptic plasticity affected by NE results from monocular occlusion, which leads to physiological and cytoarchitectural alterations in central visual areas. Selective suppression of rapid eye movement sleep (REMS in the CP kitten enhances the central effects of monocular occlusion. The mechanisms responsible for heightened cortical plasticity following REMS deprivation (REMSD remain undetermined. One possible mediator of an increase in plasticity is continuous NE outflow, which presumably persists during extended periods of REMSD. Tyrosine hydroxylase (TH is the rate-limiting enzyme in the synthesis of NE and serves as a marker for NE-producing cells. We selectively suppressed REMS in kittens for one week during the CP. The number and size of LC cells expressing immunoreactivity to tyrosine hydroxylase (TH-ir was assessed in age-matched REMS-deprived (RD-, treatment-control (TXC-, and home cage-reared (HCC animals. Sleep amounts and slow wave activity (SWA were also examined relative to baseline. Time spent in REMS during the study was lower in RD compared to TXC animals, and RD kittens increased SWA delta power in the latter half of the REMSD period. The estimated total number of TH-ir cells in LC was significantly lower in the RD- than in the TXC kittens and numerically lower than in HCC animals. The size of LC cells expressing TH-ir was greatest in the HCC group. They were significantly larger than the cells in the RD kittens. These data are consistent with a possible reduction in NE in forebrain areas, including visual cortex, caused by one week of REMSD.

  4. Size-dependent cytotoxicity of europium doped NaYF ₄ nanoparticles in endothelial cells.

    Science.gov (United States)

    Chen, Shizhu; Zhang, Cuimiao; Jia, Guang; Duan, Jianlei; Wang, Shuxiang; Zhang, Jinchao

    2014-10-01

    Lanthanide-doped sodium yttrium fluoride (NaYF4) nanoparticles exhibit novel optical properties which make them be widely used in various fields. The extensive applications increase the chance of human exposure to these nanoparticles and thus raise deep concerns regarding their riskiness. In the present study, we have synthesized europium doped NaYF4 (NaYF4:Eu(3+)) nanoparticles with three diameters and used endothelial cells (ECs) as a cell model to explore the potential toxic effect. The cell viability, cytomembrane integrity, cellular uptake, intracellular localization, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), apoptosis detection, caspase-3 activity and expression of inflammatory gene were studied. The results indicated that these nanoparticles could be uptaken into ECs and decrease the cell viability, induce the intracellular lactate dehydrogenase (LDH) release, increase the ROS level, and decrease the cell MMP in a size-dependent manner. Besides that, the cells were suffered to apoptosis with the caspase-3 activation, and the inflammation specific gene expressions (ICAM1 and VCAM1) were also increased. Our results suggest that the damage pathway may be related to the ROS generation and mitochondrial damage. The results provide novel evidence to elucidate their toxicity mechanisms and may be helpful for more rational applications of these compounds in the future. PMID:25175221

  5. A Cell-Free Assay Using Xenopus laevis Embryo Extracts to Study Mechanisms of Nuclear Size Regulation.

    Science.gov (United States)

    Edens, Lisa J; Levy, Daniel L

    2016-01-01

    A fundamental question in cell biology is how cell and organelle sizes are regulated. It has long been recognized that the size of the nucleus generally scales with the size of the cell, notably during embryogenesis when dramatic reductions in both cell and nuclear sizes occur. Mechanisms of nuclear size regulation are largely unknown and may be relevant to cancer where altered nuclear size is a key diagnostic and prognostic parameter. In vivo approaches to identifying nuclear size regulators are complicated by the essential and complex nature of nuclear function. The in vitro approach described here to study nuclear size control takes advantage of the normal reductions in nuclear size that occur during Xenopus laevis development. First, nuclei are assembled in X. laevis egg extract. Then, these nuclei are isolated and resuspended in cytoplasm from late stage embryos. After a 30 - 90 min incubation period, nuclear surface area decreases by 20 - 60%, providing a useful assay to identify cytoplasmic components present in late stage embryos that contribute to developmental nuclear size scaling. A major advantage of this approach is the relative facility with which the egg and embryo extracts can be biochemically manipulated, allowing for the identification of novel proteins and activities that regulate nuclear size. As with any in vitro approach, validation of results in an in vivo system is important, and microinjection of X. laevis embryos is particularly appropriate for these studies. PMID:27584618

  6. Energy harvesting from organic liquids in micro-sized microbial fuel cells

    KAUST Repository

    Mink, J.E.

    2014-03-07

    Micro-sized microbial fuel cells (MFCs) are miniature energy harvesters that use bacteria to convert biomass from liquids into usable power. The key challenge is transitioning laboratory test beds into devices capable of producing high power using readily available fuel sources. Here, we present a pragmatic step toward advancing MFC applications through the fabrication of a uniquely mobile and inexpensive micro-sized device that can be fueled with human saliva. The 25-ll MFC was fabricated with graphene, a two-dimensional atomic crystal-structured material, as an anode for efficient current generation and with an air cathode for enabling the use of the oxygen present in air, making its operation completely mobile and free of the need for laboratory chemicals. With saliva as a fuel, the device produced higher current densities (1190 Am-3) than any previous aircathode micro-sized MFCs. The use of the graphene anode generated 40 times more power than that possible using a carbon cloth anode. Additional tests were performed using acetate, a conventional organic material, at high organic loadings that were comparable to those in saliva, and the results demonstrated a linear relationship between the organic loading and current. These findings open the door to saliva-powered applications of this fuel cell technology for Lab-on-a-Chip devices or portable point-of-care diagnostic devices. 2014 Nature Publishing Group All rights reserved 1884-4057/14.

  7. Fine Adjustment of Interfacial Potential between pH-Responsive Hydrogels and Cell-Sized Particles.

    Science.gov (United States)

    Monzel, Cornelia; Veschgini, Mariam; Madsen, Jeppe; Lewis, Andrew L; Armes, Steven P; Tanaka, Motomu

    2015-08-11

    We quantitatively determined interfacial potentials between cell-sized particles and stimulus-responsive hydrogels using a microinterferometer. The hydrogel is based on physically interconnected ABA triblock copolymer micelles comprising an inner biocompatible PMPC block and two outer pH-responsive PDPA blocks. The out-of-plane temporal fluctuation in the position of the cell-sized particles was calculated from changes in the interference pattern measured by Reflection Interference Contrast Microscopy (RICM), thus yielding the particle-substrate interaction potential V (Δh). Measurements in pH buffers ranging from 7.0 to 7.8 resulted in a systematic reduction in height of the potential minima ⟨Δh⟩ and a concomitant increase in the potential curvature V″ (Δh). The experimental data were analyzed by applying the modified Ross and Pincus model for polyelectrolytes, while accounting for gravitation, lubrication and van der Waals interactions. Elastic moduli calculated from V″ (Δh) were in good agreement with those measured by Atomic Force Microscopy. The ability to fine-tune both the gel elasticity and the interfacial potential at around physiological pH makes such triblock copolymer hydrogels a promising biocompatible substrate for dynamic switching of cell-material interactions. PMID:26190346

  8. Pyruvate kinase isoenzyme M2 is a glycolytic sensor differentially regulating cell proliferation, cell size and apoptotic cell death dependent on glucose supply

    Energy Technology Data Exchange (ETDEWEB)

    Spoden, Gilles A. [Department of Cell Metabolism and Differentiation, Institute for Biomedical Aging Research of the Austrian Academy of Sciences, Rennweg 10, 6020 Innsbruck (Austria); Tumorvirology Research Group, Tyrolean Cancer Research Institute, Medical University Innsbruck, Innrain 66, 6020 Innsbruck (Austria); Rostek, Ursula; Lechner, Stefan; Mitterberger, Maria [Department of Cell Metabolism and Differentiation, Institute for Biomedical Aging Research of the Austrian Academy of Sciences, Rennweg 10, 6020 Innsbruck (Austria); Mazurek, Sybille [Department for Biochemistry and Endocrinology, Veterinary Faculty, University of Giessen, 35392 Giessen (Germany); ScheBo Biotech AG, Netanyastrasse 3, 35394 Giessen (Germany); Zwerschke, Werner, E-mail: werner.zwerschke@oeaw.ac.at [Department of Cell Metabolism and Differentiation, Institute for Biomedical Aging Research of the Austrian Academy of Sciences, Rennweg 10, 6020 Innsbruck (Austria); Tumorvirology Research Group, Tyrolean Cancer Research Institute, Medical University Innsbruck, Innrain 66, 6020 Innsbruck (Austria)

    2009-10-01

    The glycolytic key regulator pyruvate kinase M2 (M2-PK or PKM2) can switch between a highly active tetrameric and an inactive dimeric form. The transition between the two conformations regulates the glycolytic flux in tumor cells. We developed specific M2-PK-binding peptide aptamers which inhibit M2-PK, but not the 96% homologous M1-PK isoenzyme. In this study we demonstrate that, at normal blood glucose concentrations, peptide aptamer-mediated inhibition of M2-PK induces a significant decrease of the population doubling (PDL rate) and cell proliferation rate as well as an increase in cell size, whereas under glucose restriction an increase in PDL and cell proliferation rates but a decrease in cell size was observed. Moreover, M2-PK inhibition rescues cells from glucose starvation-induced apoptotic cell death by increasing the metabolic activity. These findings suggest that M2-PK is a metabolic sensor which regulates cell proliferation, cell growth and apoptotic cell death in a glucose supply-dependent manner.

  9. Sized controlled synthesis, purification, and cell studies with silicon quantum dots

    Science.gov (United States)

    Shiohara, Amane; Prabakar, Sujay; Faramus, Angelique; Hsu, Chia-Yen; Lai, Ping-Shan; Northcote, Peter T.; Tilley, Richard D.

    2011-08-01

    This article describes the size control synthesis of silicon quantum dots with simple microemulsion techniques. The silicon nanocrystals are small enough to be in the strong confinement regime and photoluminesce in the blue region of the visible spectrum and the emission can be tuned by changing the nanocrystal size. The silicon quantum dots were capped with allylamine either a platinum catalyst or UV-radiation. An extensive purification protocol is reported and assessed using 1H NMR to produce ultra pure silicon quantum dots suitable for biological studies. The highly pure quantum dots were used in cellular uptake experiments and monitored using confocal microscopy. The results showed that the amine terminated silicon nanocrystals accumulated in lysosome but not in nuclei and could be used as bio-markers to monitor cancer cells over long timescales.This article describes the size control synthesis of silicon quantum dots with simple microemulsion techniques. The silicon nanocrystals are small enough to be in the strong confinement regime and photoluminesce in the blue region of the visible spectrum and the emission can be tuned by changing the nanocrystal size. The silicon quantum dots were capped with allylamine either a platinum catalyst or UV-radiation. An extensive purification protocol is reported and assessed using 1H NMR to produce ultra pure silicon quantum dots suitable for biological studies. The highly pure quantum dots were used in cellular uptake experiments and monitored using confocal microscopy. The results showed that the amine terminated silicon nanocrystals accumulated in lysosome but not in nuclei and could be used as bio-markers to monitor cancer cells over long timescales. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr10458f

  10. The Homeodomain Iroquois Proteins Control Cell Cycle Progression and Regulate the Size of Developmental Fields.

    Directory of Open Access Journals (Sweden)

    Natalia Barrios

    2015-08-01

    Full Text Available During development, proper differentiation and final organ size rely on the control of territorial specification and cell proliferation. Although many regulators of these processes have been identified, how both are coordinated remains largely unknown. The homeodomain Iroquois/Irx proteins play a key, evolutionarily conserved, role in territorial specification. Here we show that in the imaginal discs, reduced function of Iroquois genes promotes cell proliferation by accelerating the G1 to S transition. Conversely, their increased expression causes cell-cycle arrest, down-regulating the activity of the Cyclin E/Cdk2 complex. We demonstrate that physical interaction of the Iroquois protein Caupolican with Cyclin E-containing protein complexes, through its IRO box and Cyclin-binding domains, underlies its activity in cell-cycle control. Thus, Drosophila Iroquois proteins are able to regulate cell-autonomously the growth of the territories they specify. Moreover, our results provide a molecular mechanism for a role of Iroquois/Irx genes as tumour suppressors.

  11. Effect of Particle Size in Aggregates of ZnO-Aggregate-Based Dye-Sensitized Solar Cells

    International Nuclear Information System (INIS)

    Graphical abstract: The crystal size in submicrometer ZnO aggregates plays an important role in the ZnO-aggregate-based dye-sensitized solar cells. Optimal crystal size in aggregates leads to balance parameters of dye absorption, electron diffusion between crystals and recombination to get higher light-to-electricity conversion efficiency. - Highlights: • A new method is developed for controlling crystal size in ZnO aggregate. • Dye adsorption, electron diffusion and recombination depend on crystal size in the aggregates. • 20-30 nm crystal size in aggregates can optimize these factors to achieve higher efficiency of DSC. - Abstract: Effect of particle size in aggregates on ZnO-aggregate-based dye-sensitized solar cells is investigated. A two-step hydrothermal method is developed for preparing submicrometer ZnO aggregates with different crystal sizes via controlling regrowth temperature. Three groups of ZnO-aggregate-based dye-sensitized solar cells with the different crystal sizes in the aggregates are fabricated for comparison of the photovoltaic properties. The results indicate that the cell made of crystal size of 25-30 nm has the highest light-to-electricity conversion efficiency of 4.54% for the dye-sensitized solar cells. According to the analysis of absorption spectra, dark current curves, photoelectron decay and electrochemical impedance spectra, we find that the aggregates with smaller crystal size have higher capability of dye adsorption, while the aggregates with larger crystal size have faster electron diffusion, and less recombination. Therefore, optimal crystal size in the aggregates for photoanode leads to balance these parameters to get higher light-to-electricity conversion efficiency. This investigation is important to the improvement of conversion efficiency for dye-sensitized solar cells

  12. Toxicity of nano- and micro-sized silver particles in human hepatocyte cell line L02

    Science.gov (United States)

    Liu, Pengpeng; Guan, Rongfa; Ye, Xingqian; Jiang, Jiaxin; Liu, Mingqi; Huang, Guangrong; Chen, Xiaoting

    2011-07-01

    Silver nanoparticles (Ag NPs) previously classified as antimicrobial agents have been widely used in consumers and industrial products, especially food storage material. Ag NPs used as antimicrobial agents may be found in liver. Thus, examination of the ability of Ag NPs to penetrate the liver is warranted. The aim of the study was to determine the optimal viability assay for using with Ag NPs in order to assess their toxicity to liver cells. For toxicity evaluations, cellular morphology, mitochondrial function (3-(4, 5-dimethylazol-2-yl)-2, 5-diphenyl-tetrazolium bromide, MTT assay), membrane leakage of lactate dehydrogenase (lactate dehydrogenase, LDH release assay), Oxidative stress markers (malonaldehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD)), DNA damage (single cell gel eletrophoresis, SCGE assay), and protein damage were assessed under control and exposed conditions (24 h of exposure). The results showed that mitochondrial function decreased significantly in cells exposed to Ag NPs at 25 μg·mL-1. LDH leakage significantly increased in cells exposed to Ag NPs (>= 25 μg mL-1) while micro-sized silver particles tested displayed LDH leakage only at higher doses (100 μg·mL-1). The microscopic studies demonstrated that nanoparticle-exposed cells at higher doses became abnormal in size, displaying cellular shrinkage, and an acquisition of an irregular shape. Due to toxicity of silver, further study conducted with reference to its oxidative stress. The results exhibited significant depletion of GSH level, increase in SOD levels and lead to lipid peroxidation, which suggested that cytotoxicity of Ag NPs in liver cells might be mediated through oxidative stress. The results demonstrates that Ag NPs lead to cellular morphological modifications, LDH leakage, mitochondrial dysfunction, and cause increased generation of ROS, depletion of GSH, lipid peroxidation, oxidative DNA damage and protein damage. Though the exact mechanism behind Ag NPs

  13. Excellent endurance of MWCNT anode in micro-sized Microbial Fuel Cell

    KAUST Repository

    Mink, Justine E.

    2012-08-01

    Microbial Fuel Cells (MFCs) are a sustainable technology for energy production using bioelectrochemical reactions from bacteria. Microfabrication of micro-sized MFCs allows rapid and precise production of devices that can be integrated into Lab-on-a-chip or other ultra low power devices. We show a multi-walled carbon nanotubes (MWCNTs) integrated anode in a biocompatible and high power and current producing device. Long term testing of the MWCNT anode also reveals a high endurance and durable anode material that can be adapted as a long-lasting power source. © 2012 IEEE.

  14. One size does not fit all: developing a cell-specific niche for in vitro study of cell behavior.

    Science.gov (United States)

    Marinkovic, Milos; Block, Travis J; Rakian, Rubie; Li, Qihong; Wang, Exing; Reilly, Matthew A; Dean, David D; Chen, Xiao-Dong

    2016-01-01

    .g. collagen and fibronectin) were found at equivalent levels in both BM- and AD-ECM, the architecture (i.e. fiber orientation; surface roughness) and physical properties (storage modulus, surface energy) of each were unique. These results, demonstrating differences in cell behavior when cultured on the three different substrates (BM- and AD-ECM and TCP) with differences in chemical and physical properties, provide evidence that the two ECMs may recapitulate specific elements of the native stem cell niche for bone marrow and adipose tissues. More broadly, it could be argued that ECMs, elaborated by cells ex vivo, serve as an ideal starting point for developing tissue-specific culture environments. In contrast to TCP, which relies on the "one size fits all" paradigm, native tissue-specific ECM may be a more rational model to approach engineering 3D tissue-specific culture systems to replicate the in vivo niche. We suggest that this approach will provide more meaningful information for basic research studies of cell behavior as well as cell-based therapeutics. PMID:26780725

  15. Redefinition of cell size classification of phytoplankton – a potential tool for improving the quality and assurance of data interpretation

    OpenAIRE

    L. IGNATIADES

    2014-01-01

    To date, phytoplankton cell size classification is based on linear metrics (nano: 2-20 μm; micro: 20-200 μm; macro: >200 μm) although three-dimensional metrics are used for cell or body size descriptions of all terrestrial and aquatic organisms. This study proposes a redefinition of phytoplankton size classification expressed in terms of cell volume (μm3) metrics by analyzing statistically a data set of 397 species from three major groups of eukaryotic taxa (diatoms, dinoflagellates, cocc...

  16. Cell responses to two kinds of nanohydroxyapatite with different sizes and crystallinities

    Directory of Open Access Journals (Sweden)

    Wei SC

    2012-03-01

    Full Text Available Xiaochen Liu1, Minzhi Zhao1, Jingxiong Lu2, Jian Ma4, Jie Wei2, Shicheng Wei1,31Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 2Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai, 3Department of Oral and Maxillofacial Surgery, School of Stomatology, Peking University, Beijing, 4Hospital of Stomatology, Tongji University, Shanghai, ChinaIntroduction:Hydroxyapatite (HA is the principal inorganic constituent of human bone. Due to its good biocompatibility and osteoconductivity, all kinds of HA particles were prepared by different methods. Numerous reports demonstrated that the properties of HA affected its biological effects.Methods: Two kinds of nanohydroxyapatite with different sizes and crystallinities were obtained via a hydrothermal treatment method under different temperatures. It was found that at a temperature of 140°C, a rod-like crystal (n-HA1 with a diameter of 23 ± 5 nm, a length of 47 ± 14 nm, and crystallinity of 85% ± 5% was produced, while at a temperature of 80°C, a rod-like crystal (n-HA2 with a diameter of 16 ± 3 nm, a length of 40 ± 10 nm, and crystallinity of 65% ± 3% was produced. The influence of nanohydroxyapatite size and crystallinity on osteoblast viability was studied by MTT, scanning electron microscopy, and flow cytometry.Results: n-HA1 gave a better biological response than n-HA2 in promoting cell growth and inhibiting cell apoptosis, and also exhibited much more active cell morphology. Alkaline phosphatase activity for both n-HA2 and n-HA1 was obviously higher than for the control, and no significant difference was found between n-HA1 and n-HA2. The same trend was observed on Western blotting for expression of type I collagen and osteopontin. In addition, it was found by transmission electron microscopy that large quantities of n-HA2 entered into the cell

  17. Structural Transition of Actin Filament in a Cell-Sized Water Droplet with a Phospholipid Membrane

    CERN Document Server

    Hase, M

    2005-01-01

    Actin filament, F-actin, is a semiflexible polymer with a negative charge, and is one of the main constituents on cell membranes. To clarify the effect of cross-talk between a phospholipid membrane and actin filaments in cells, we conducted microscopic observations on the structural changes in actin filaments in a cell-sized (several tens of micrometers in diameter) water droplet coated with a phospholipid membrane such as phosphatidylserine (PS; negatively-charged head group) or phosphatidylethanolamine (PE; neutral head group) as a simple model of a living cell membrane. With PS, actin filaments are distributed uniformly in the water phase without adsorption onto the membrane surface between 2 and 6 mM Mg2+, while between 6 and 12 mM Mg2+, actin filaments are adsorbed onto the inner membrane surface. With PE, actin filaments are uniformly adsorbed onto the inner membrane surface between 2 and 12 mM Mg2+. With both PS and PE membranes, at Mg2+ concentrations higher than 12 mM, thick bundles are formed in the...

  18. Investigation of Low-Cost Surface Processing Techniques for Large-Size Multicrystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Shun-Hsyung Chang

    2010-01-01

    Full Text Available The subject of the present work is to develop a simple and effective method of enhancing conversion efficiency in large-size solar cells using multicrystalline silicon (mc-Si wafer. In this work, industrial-type mc-Si solar cells with area of 125×125 mm2 were acid etched to produce simultaneously POCl3 emitters and silicon nitride deposition by plasma-enhanced chemical vapor deposited (PECVD. The study of surface morphology and reflectivity of different mc-Si etched surfaces has also been discussed in this research. Using our optimal acid etching solution ratio, we are able to fabricate mc-Si solar cells of 16.34% conversion efficiency with double layers silicon nitride (Si3N4 coating. From our experiment, we find that depositing double layers silicon nitride coating on mc-Si solar cells can get the optimal performance parameters. Open circuit (Voc is 616 mV, short circuit current (Jsc is 34.1 mA/cm2, and minority carrier diffusion length is 474.16 μm. The isotropic texturing and silicon nitride layers coating approach contribute to lowering cost and achieving high efficiency in mass production.

  19. Cell size dependence of additive versus synergetic effects of UV radiation and PAHs on oceanic phytoplankton

    Energy Technology Data Exchange (ETDEWEB)

    Echeveste, Pedro, E-mail: pecheveste@imedea.uib-csic.es [Department of Global Change Research, IMEDEA (CSIC-UIB) Instituto Mediterraneo de Estudios Avanzados, Miquel Marques 21, 07190 Esporles, Illes Balears (Spain); Agusti, Susana [Department of Global Change Research, IMEDEA (CSIC-UIB) Instituto Mediterraneo de Estudios Avanzados, Miquel Marques 21, 07190 Esporles, Illes Balears (Spain); Dachs, Jordi [Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research, IDAEA-CSIC, Barcelona, Catalunya (Spain)

    2011-05-15

    Polycyclic Aromatic Hydrocarbons' (PAHs) toxicity is enhanced by the presence of ultraviolet radiation (UVR), which levels have arisen due to the thinning of the ozone layer. In this study, PAHs' phototoxicity for natural marine phytoplankton was tested. Different concentrations of a mixture of 16 PAHs were added to natural phytoplankton communities from the Mediterranean Sea, Atlantic, Arctic and Southern Oceans and exposed to natural sunlight received in situ, including treatments where the UVR bands were removed. PAHs' toxicity was observed for all the phytoplankton groups studied in all the waters and treatments tested, but only for the pico-sized group a synergetic effect of the mixture and UVR was observed (p = 0.009). When comparing phototoxicity in phytoplankton from oligotrophic and eutrophic waters, synergy was only observed at the oligotrophic communities (p = 0.02) where pico-sized phytoplankton dominated. The degree of sensitivity was related to the trophic degree, decreasing as Chlorophyll a concentration increased. - Highlights: > The smallest picocyanobacteria were the most sensitive to PAHs and UVR. > PAHs-UVR synergism for the picophytoplankton and the oligotrophic communities. > PAHs-UVR additivity for the nanophytoplankton and the eutrophic communities. > An irradiance threshold is suggested to determine the joint action of UVR and PAHs. - Cell size and UVR levels determine additive/synergetic effects of PAHs and UVR to oceanic phytoplankton.

  20. Cell size dependence of additive versus synergetic effects of UV radiation and PAHs on oceanic phytoplankton

    International Nuclear Information System (INIS)

    Polycyclic Aromatic Hydrocarbons' (PAHs) toxicity is enhanced by the presence of ultraviolet radiation (UVR), which levels have arisen due to the thinning of the ozone layer. In this study, PAHs' phototoxicity for natural marine phytoplankton was tested. Different concentrations of a mixture of 16 PAHs were added to natural phytoplankton communities from the Mediterranean Sea, Atlantic, Arctic and Southern Oceans and exposed to natural sunlight received in situ, including treatments where the UVR bands were removed. PAHs' toxicity was observed for all the phytoplankton groups studied in all the waters and treatments tested, but only for the pico-sized group a synergetic effect of the mixture and UVR was observed (p = 0.009). When comparing phototoxicity in phytoplankton from oligotrophic and eutrophic waters, synergy was only observed at the oligotrophic communities (p = 0.02) where pico-sized phytoplankton dominated. The degree of sensitivity was related to the trophic degree, decreasing as Chlorophyll a concentration increased. - Highlights: → The smallest picocyanobacteria were the most sensitive to PAHs and UVR. → PAHs-UVR synergism for the picophytoplankton and the oligotrophic communities. → PAHs-UVR additivity for the nanophytoplankton and the eutrophic communities. → An irradiance threshold is suggested to determine the joint action of UVR and PAHs. - Cell size and UVR levels determine additive/synergetic effects of PAHs and UVR to oceanic phytoplankton.

  1. ELISPOTs Produced by CD8 and CD4 Cells Follow Log Normal Size Distribution Permitting Objective Counting

    Directory of Open Access Journals (Sweden)

    Alexey Y. Karulin

    2015-01-01

    Full Text Available Each positive well in ELISPOT assays contains spots of variable sizes that can range from tens of micrometers up to a millimeter in diameter. Therefore, when it comes to counting these spots the decision on setting the lower and the upper spot size thresholds to discriminate between non-specific background noise, spots produced by individual T cells, and spots formed by T cell clusters is critical. If the spot sizes follow a known statistical distribution, precise predictions on minimal and maximal spot sizes, belonging to a given T cell population, can be made. We studied the size distributional properties of IFN-γ, IL-2, IL-4, IL-5 and IL-17 spots elicited in ELISPOT assays with PBMC from 172 healthy donors, upon stimulation with 32 individual viral peptides representing defined HLA Class I-restricted epitopes for CD8 cells, and with protein antigens of CMV and EBV activating CD4 cells. A total of 334 CD8 and 80 CD4 positive T cell responses were analyzed. In 99.7% of the test cases, spot size distributions followed Log Normal function. These data formally demonstrate that it is possible to establish objective, statistically validated parameters for counting T cell ELISPOTs.

  2. Improved Light Conversion Efficiency Of Dye-Sensitized Solar Cell By Dispersing Submicron-Sized Granules Into The Nano-Sized TiO2 Layer

    Directory of Open Access Journals (Sweden)

    Song S.A.

    2015-06-01

    Full Text Available In this work, TiO2 nanoparticles and submicron-sized granules were synthesized by a hydrothermal method and spray pyrolysis, respectively. Submicron-sized granules were dispersed into the nano-sized TiO2 layer to improve the light conversion efficiency. Granules showed better light scattering, but lower in terms of the dye-loading quantity and recombination resistance compared with nanoparticles. Consequently, the nano-sized TiO2 layer had higher cell efficiency than the granulized TiO2 layer. When dispersed granules into the nanoparticle layer, the light scattering was enhanced without the loss of dye-loading quantities. The dispersion of granulized TiO2 led to increase the cell efficiency up to 6.51%, which was about 5.2 % higher than that of the electrode consisting of only TiO2 nanoparticles. Finally, the optimal hydrothermal temperature and dispersing quantity of granules were found to be 200°C and 20 wt%, respectively.

  3. Comparative effects of macro-sized aluminum oxide and aluminum oxide nanoparticles on erythrocyte hemolysis: influence of cell source, temperature, and size

    International Nuclear Information System (INIS)

    Al2O3 is the most abundantly produced nanomaterial and has been used in diverse fields, including the medical, military, and industrial sectors. As there are concerns about the health effects of nanoparticles, it is important to understand how they interact with cells, and specifically with red blood cells. The hemolysis induced by three commercial nano-sized aluminum oxide particles (nanopowder 13 nm, nanopowder <50 nm, and nanowire 2–6 × 200–400 nm) was compared to aluminum oxide and has been studied on erythrocytes from humans, rats, and rabbits, in order to elucidate the mechanism of action and the influence of size and shape on hemolytic behavior. The concentrations inducing 50 % hemolysis (HC50) were calculated for each compound studied. The most hemolytic aluminum oxide particles were of nanopowder 13, followed by nanowire and nanopowder 50. The addition of albumin to PBS induced a protective effect on hemolysis in all the nano-forms of Al2O3, but not on Al2O3. The drop in HC50 correlated to a decrease in nanomaterial size, which was induced by a reduction of aggregation. Aluminum oxide nanoparticles are less hemolytic than other oxide nanoparticles and behave differently depending on the size and shape of the nanoparticles. The hemolytic behavior of aluminum oxide nanoparticles differs from that of aluminum oxide

  4. Comparative effects of macro-sized aluminum oxide and aluminum oxide nanoparticles on erythrocyte hemolysis: influence of cell source, temperature, and size

    Energy Technology Data Exchange (ETDEWEB)

    Vinardell, M. P., E-mail: mpvinardellmh@ub.edu; Sordé, A. [Universitat de Barcelona, Departament de Fisiologia, Facultat de Farmàcia (Spain); Díaz, J. [Universitat de Barcelona CCiT, Scientific and Technological Centers (Spain); Baccarin, T.; Mitjans, M. [Universitat de Barcelona, Departament de Fisiologia, Facultat de Farmàcia (Spain)

    2015-02-15

    Al{sub 2}O{sub 3} is the most abundantly produced nanomaterial and has been used in diverse fields, including the medical, military, and industrial sectors. As there are concerns about the health effects of nanoparticles, it is important to understand how they interact with cells, and specifically with red blood cells. The hemolysis induced by three commercial nano-sized aluminum oxide particles (nanopowder 13 nm, nanopowder <50 nm, and nanowire 2–6 × 200–400 nm) was compared to aluminum oxide and has been studied on erythrocytes from humans, rats, and rabbits, in order to elucidate the mechanism of action and the influence of size and shape on hemolytic behavior. The concentrations inducing 50 % hemolysis (HC{sub 50}) were calculated for each compound studied. The most hemolytic aluminum oxide particles were of nanopowder 13, followed by nanowire and nanopowder 50. The addition of albumin to PBS induced a protective effect on hemolysis in all the nano-forms of Al{sub 2}O{sub 3}, but not on Al{sub 2}O{sub 3}. The drop in HC{sub 50} correlated to a decrease in nanomaterial size, which was induced by a reduction of aggregation. Aluminum oxide nanoparticles are less hemolytic than other oxide nanoparticles and behave differently depending on the size and shape of the nanoparticles. The hemolytic behavior of aluminum oxide nanoparticles differs from that of aluminum oxide.

  5. Interspecies avian brain chimeras reveal that large brain size differences are influenced by cell-interdependent processes.

    Science.gov (United States)

    Chen, Chun-Chun; Balaban, Evan; Jarvis, Erich D

    2012-01-01

    Like humans, birds that exhibit vocal learning have relatively delayed telencephalon maturation, resulting in a disproportionately smaller brain prenatally but enlarged telencephalon in adulthood relative to vocal non-learning birds. To determine if this size difference results from evolutionary changes in cell-autonomous or cell-interdependent developmental processes, we transplanted telencephala from zebra finch donors (a vocal-learning species) into Japanese quail hosts (a vocal non-learning species) during the early neural tube stage (day 2 of incubation), and harvested the chimeras at later embryonic stages (between 9-12 days of incubation). The donor and host tissues fused well with each other, with known major fiber pathways connecting the zebra finch and quail parts of the brain. However, the overall sizes of chimeric finch telencephala were larger than non-transplanted finch telencephala at the same developmental stages, even though the proportional sizes of telencephalic subregions and fiber tracts were similar to normal finches. There were no significant changes in the size of chimeric quail host midbrains, even though they were innervated by the physically smaller zebra finch brain, including the smaller retinae of the finch eyes. Chimeric zebra finch telencephala had a decreased cell density relative to normal finches. However, cell nucleus size differences between each species were maintained as in normal birds. These results suggest that telencephalic size development is partially cell-interdependent, and that the mechanisms controlling the size of different brain regions may be functionally independent. PMID:22860132

  6. Interspecies avian brain chimeras reveal that large brain size differences are influenced by cell-interdependent processes.

    Directory of Open Access Journals (Sweden)

    Chun-Chun Chen

    Full Text Available Like humans, birds that exhibit vocal learning have relatively delayed telencephalon maturation, resulting in a disproportionately smaller brain prenatally but enlarged telencephalon in adulthood relative to vocal non-learning birds. To determine if this size difference results from evolutionary changes in cell-autonomous or cell-interdependent developmental processes, we transplanted telencephala from zebra finch donors (a vocal-learning species into Japanese quail hosts (a vocal non-learning species during the early neural tube stage (day 2 of incubation, and harvested the chimeras at later embryonic stages (between 9-12 days of incubation. The donor and host tissues fused well with each other, with known major fiber pathways connecting the zebra finch and quail parts of the brain. However, the overall sizes of chimeric finch telencephala were larger than non-transplanted finch telencephala at the same developmental stages, even though the proportional sizes of telencephalic subregions and fiber tracts were similar to normal finches. There were no significant changes in the size of chimeric quail host midbrains, even though they were innervated by the physically smaller zebra finch brain, including the smaller retinae of the finch eyes. Chimeric zebra finch telencephala had a decreased cell density relative to normal finches. However, cell nucleus size differences between each species were maintained as in normal birds. These results suggest that telencephalic size development is partially cell-interdependent, and that the mechanisms controlling the size of different brain regions may be functionally independent.

  7. Methods to recover the narrow Dicke sub-Doppler feature in evacuated wall-coated cells without restrictions on cell size

    Science.gov (United States)

    Robinson, H. G.

    1984-01-01

    The hyperfine resonance observed in evacuated wall-coated cells with dimensions lambda/2 (lambda is the hyperfine resonance wavelength) consists of a narrow Dicke sub-Doppler linewidth feature, the spike, superimposed on a broad pedestal. The hydrogen maser provides a classic example of this lineshape. As cell size is increased, an effect unique to evacuated wall-coated cells occurs. Certain combinations of microwave field distribution and cell size result in a lineshape having a pedestal with a small spike feature or only the broad pedestal with no spike. Such conditions are not appropriate for atomic frequency standard applications. The cause of the evacuated wall-coated cell lineshape is reviewed and methods to recover the narrow spike feature without restrictions on cell size is discussed. One example is a cell with dimensions having equal volumes of exposure to opposite phases of the microwave magnetic field.

  8. Realization of high performance silicon nanowire based solar cells with large size

    International Nuclear Information System (INIS)

    We report the realization of high performance silicon nanowire (SiNW) based solar cells with a conversion efficiency of 17.11% and a large size of 125 × 125 mm2. The key factor for success lies in an efficient approach of dielectric passivation to greatly enhance the electrical properties while keeping the advantage of excellent light trapping of the SiNW structure. The suppression of carrier recombination has been demonstrated through the combination of the SiO2/SiNx stack, which exhibits a good passivation effect on heavily doped SiNWs via reducing both the Shockley–Read–Hall recombination and near surface Auger recombination. We have examined in detail the effects of different passivations and SiNW lengths on the effective minority carrier lifetime, reflectance and carrier recombination characteristics, as well as cell performance. The proposed passivation techniques can be easily adapted to conventional industrial manufacturing processes, providing a potential prospect of SiNW based solar cells in mass production. (paper)

  9. MODELING, SIMULATON AND SIZING OF PHOTOVOLTAIC/WIND/FUEL CELL HYBRID GENERATION SYSTEM

    Directory of Open Access Journals (Sweden)

    Dr.S.LATHA

    2012-05-01

    Full Text Available The depleting fossil fuel reserves and increasing concern towards global warming have created the need to surge for the alternative power generation options. Renewable energy sources like Wind, Solar-PV, Biomass and fuel cells are gaining prominence nowadays, as they are more energy efficient, reduce pollution and also they serveas a promising solution to the toughest energy crisis faced during the recent years. This paper focuses on the modeling and simulation of solar – photovoltaic, wind and fuel cell hybrid energy systems using MATLAB/Simulink software. The intermittent nature of solar and wind energy sources make them unreliable. Hence Maximum Power Point Tracking (MPPT is used to extract maximum power from the wind and sunwhen it is available. The standard perturb and observe method of MPPT is used for the PV system and for the wind generation system. The simulation results of the PV/Wind /Fuel cell hybrid system are presented in graph showing the effectiveness of the proposed system model. Also, hardware implementation of microcontroller based MPPT for solar-PV alone and unit sizing of the hybrid system for the PG simulation lab in EEE Dept. of Thiagarajar College of Engineering is depicted in the paper.

  10. Size, Shape, and Arrangement of Cellulose Microfibril in Higher Plant Cell Walls

    Energy Technology Data Exchange (ETDEWEB)

    Ding, S. Y.

    2013-01-01

    Plant cell walls from maize (Zea mays L.) are imaged using atomic force microscopy (AFM) at the sub-nanometer resolution. We found that the size and shape of fundamental cellulose elementary fibril (CEF) is essentially identical in different cell wall types, i.e., primary wall (PW), parenchyma secondary wall (pSW), and sclerenchyma secondary wall (sSW), which is consistent with previously proposed 36-chain model (Ding et al., 2006, J. Agric. Food Chem.). The arrangement of individual CEFs in these wall types exhibits two orientations. In PW, CEFs are horizontally associated through their hydrophilic faces, and the planar faces are exposed, forming ribbon-like macrofibrils. In pSW and sSW, CEFs are vertically oriented, forming layers, in which hemicelluloses are interacted with the hydrophobic faces of the CEF and serve as spacers between CEFs. Lignification occurs between CEF-hemicelluloses layers in secondary walls. Furthermore, we demonstrated quantitative analysis of plant cell wall accessibility to and digestibility by different cellulase systems at real-time using chemical imaging (e.g., stimulated Raman scattering) and fluorescence microscopy of labeled cellulases (Ding et al., 2012, Science, in press).

  11. A novel method for evaluating microglial activation using ionized calcium-binding adaptor protein-1 staining: cell body to cell size ratio

    Directory of Open Access Journals (Sweden)

    Iris Bertha Hovens

    2014-09-01

    Full Text Available Aim: The aim was to validate a newly developed methodology of semi-automatic image analysis to analyze microglial morphology as marker for microglial activation in ionized calcium-binding adaptor protein-1 (IBA-1 stained brain sections. Methods: The novel method was compared to currently used analysis methods, visual characterization of activation stage and optical density measurement, in brain sections of young and aged rats that had undergone surgery or remained naοve. Results: The cell body to cell size ratio of microglia was strongly correlated to the visual characterization activation stage. In addition, we observed specific surgery and age-related changes in cell body size, size of the dendritic processes and cell body to cell size ratio. Conclusion: The novel analysis method provides a sensitive marker for microglial activation in the rat brain, which is quick and easy to perform and provides additional information about microglial morphology.

  12. Flexible and elastic metamaterial absorber for low frequency, based on small-size unit cell

    International Nuclear Information System (INIS)

    Using a planar and flexible metamaterial (MM), we obtained the low-frequency perfect absorption even with very small unit-cell size in snake-shape structure. These shrunken, deep-sub-wavelength and thin MM absorbers were numerically and experimentally investigated by increasing the inductance. The periodicity/thickness (the figure of merit for perfect absorption) is achieved to be 10 and 2 for single-snake-bar and 5-snake-bar structures, respectively. The ratio between periodicity and resonance wavelength (in mm) is close to 1/12 and 1/30 at 2 GHz and 400 MHz, respectively. The absorbers are specially designed for absorption peaks around 2 GHz and 400 MHz, which can be used for depressing the electromagnetic noise from everyday electronic devices and mobile phones.

  13. Quantum dot-sized organic fluorescent dots for long-term cell tracing

    Science.gov (United States)

    Li, Kai; Tang, Ben Zhong; Liu, Bin

    2014-03-01

    Fluorescence techniques have been extensively employed to develop non-invasive methodologies for tracking and understanding complex biological processes both in vitro and in vivo, which is of high importance in modern life science research. Among a variety of fluorescent probes, inorganic semiconductor quantum dots (QDs) have shown advantages in terms of better photostability, larger Stokes shift and more feasible surface functionalization. However, their intrinsic toxic heavy metal components and unstable fluorescence at low pH greatly impede the applications of QDs in in vivo studies. In this work, we developed novel fluorescent probes that can outperform currently available QD based probes in practice. Using conjugated oligomer with aggregation-induced emission characteristics as the fluorescent domain and biocompatible lipid-PEG derivatives as the encapsulation matrix, the obtained organic dots have shown higher brightness, better stability in biological medium and comparable size and photostability as compared to their counterparts of inorganic QDs. More importantly, unlike QD-based probes, the organic fluorescent dots do not blink, and also do not contain heavy metal ions that could be potentially toxic when applied for living biosubstrates. Upon surface functionalization with a cell-penetrating peptide, the organic dots greatly outperform inorganic quantum dots in both in vitro and in vivo long-term cell tracing studies, which will be beneficial to answer crucial questions in stem cell/immune cell therapies. Considering the customized fluorescent properties and surface functionalities of the organic dots, a series of biocompatible organic dots will be developed to serve as a promising platform for multifarious bioimaging tasks in future.

  14. Three-Dimensional Tissue Models Constructed by Cells with Nanometer- or Micrometer-Sized Films on the Surfaces.

    Science.gov (United States)

    Liu, Chun-Yen; Matsusaki, Michiya; Akashi, Mitsuru

    2016-04-01

    Living tissues or organ modules consist of different types of highly organized cells and extracellular matrices (ECMs) in a hierarchical manner, such as the multilayered structure of blood vessels and the radial structures of hepatic lobules. Due to animal examinations being banned in the EU since 2013 and a shortage in the demand for tissue repair or organ transplantation, the creation of artificial 3D tissues possessing specific structures and functions similar to natural tissues are key challenges in tissue engineering. To date, we have developed a simple but unique bottom-up approach, a hierarchical cell manipulation technique, with a nanometer-sized ECM matrix consisting of fibronectin (FN) and gelatin (G) on cell surfaces. About 10 nm thick FN/G ECM films on cell surfaces were coated successfully by using layer-by-layer coating methodology. Various 3D constructs with higher cell density with different types of cells were successfully constructed. In addition to the construction of tissues with higher cell densities, other tissues, such as cartilage or skin tissues, with different cell densities are also important tissue models for tissue engineering and pharmaceutical industries. Thus, we recently developed other methodologies, the collagen coating method and multiple coating method, to fabricate micrometer-sized level ECM layers on cell surfaces. Various micro- or millimeter-sized 3D constructs with lower cell densities were constructed successfully. By using these two methods, cell distances in 2D or 3D views can be controlled by different thicknesses of ECM layers on cell surfaces at the single-cell level. Both FN/G and the collagen coating method resulted in homogenous 3D tissues with a controlled layer numbers, cell type, cell location, and properties; these will be promising to achieve different goals in tissue engineering. PMID:26924465

  15. Effect of cell size and shear stress on bacterium growth rate

    Science.gov (United States)

    Fadlallah, Hadi; Jarrahi, Mojtaba; Herbert, Éric; Peerhossaini, Hassan; PEF Team

    2015-11-01

    Effect of shear stress on the growth rate of Synechocystis and Chlamydomonas cells is studied. An experimental setup was prepared to monitor the growth rate of the microorganisms versus the shear rate inside a clean room, under atmospheric pressure and 20 °C temperature. Digital magnetic agitators are placed inside a closed chamber provided with airflow, under a continuous uniform light intensity over 4 weeks. In order to study the effect of shear stress on the growth rate, different frequencies of agitation are tested, 2 vessels filled with 150 ml of each specie were placed on different agitating system at the desired frequency. The growth rate is monitored daily by measuring the optical density and then correlate it to the cellular concentration. The PH was adjusted to 7 in order to maintain the photosynthetic activity. Furthermore, to measure the shear stress distribution, the flow velocity field was measured using PIV. Zones of high and low shear stress were identified. Results show that the growth rate is independent of the shear stress magnitude, mostly for Synechocystis, and with lower independency for Chlamydomonas depending on the cell size for each species.

  16. The stealthy nano-machine behind mast cell granule size distribution.

    Science.gov (United States)

    Hammel, Ilan; Meilijson, Isaac

    2015-01-01

    The classical model of mast cell secretory granule formation suggests that newly synthesized secretory mediators, transported from the rough endoplasmic reticulum to the Golgi complex, undergo post-transitional modification and are packaged for secretion by condensation within membrane-bound granules of unit size. These unit granules may fuse with other granules to form larger granules that reside in the cytoplasm until secreted. A novel stochastic model for mast cell granule growth and elimination (G&E) as well as inventory management is presented. Resorting to a statistical mechanics approach in which SNAP (Soluble NSF Attachment Protein) REceptor (SNARE) components are viewed as interacting particles, the G&E model provides a simple 'nano-machine' of SNARE self-aggregation that can perform granule growth and secretion. Granule stock is maintained as a buffer to meet uncertainty in demand by the extracellular environment and to serve as source of supply during the lead time to produce granules of adaptive content. Experimental work, mathematical calculations, statistical modeling and a rationale for the emergence of nearly last-in, first out inventory management, are discussed. PMID:24629227

  17. High-speed counting and sizing of cells in an impedance flow microcytometer with compact electronic instrumentation

    DEFF Research Database (Denmark)

    Castillo-Fernandez, Oscar; Rodriguez-Trujíllo, Romén; Gomila, Gabriel;

    2014-01-01

    Here we describe a high-throughput impedance flow cytometer on a chip. This device was built using compact and inexpensive electronic instrumentation. The system was used to count and size a mixed cell sample containing red blood cells and white blood cells. It demonstrated a counting capacity of...... up to ~500 counts/s and was validated through a synchronised high-speed optical detection system. In addition, the device showed excellent discrimination performance under high-throughput conditions....

  18. Application of thermal lens response to monitor health status of red blood cells: A quantitative study of the cell death process by extracting thermal diffusivity and size

    Science.gov (United States)

    Vasudevan, Srivathsan; Chen, George Chung Kit; Andika, Marta

    2010-03-01

    We explore monitoring the death process of individual red blood cells (RBC) quantitatively by using thermal lens (TL) response. TL response is a noninvasive excitation/probe technique that reflects photothermal parameters (e.g., absorption, thermal diffusivity, size, etc.). Since these parameters of cells change significantly during certain biological processes, real-time TL response was performed to monitor RBC death process when incubated with ionomycin. Theoretical model developed was applied to curve-fit the TL response for extracting thermal diffusivity and size of cells. Thermal diffusivity of dying RBC is found increased by 1.7 times in comparison with healthy cell.

  19. Lipid Droplets Characterization in Adipocyte Differentiated 3T3-L1 Cells: Size and Optical Density Distribution

    OpenAIRE

    V. Rizzatti; F. Boschi; Pedrotti, M.; E. Zoico; A. Sbarbati; Zamboni, M.

    2013-01-01

    The 3T3-L1 cell line, derived from 3T3 cells, is widely used in biological research on adipose tissue. 3T3-L1 cells have a fibroblast-like morphology, but, under appropriate conditions, they differentiate into an adipocyte-like phenotype. During the differentiation process, 3T3-L1 cells increase the synthesis of triglycerides and acquire the behavior of adipose cells. In particular, triglycerides accumulate in lipid droplets (LDs) embedded in the cytoplasm. The number and the size distributio...

  20. Insulin/IGF-regulated size scaling of neuroendocrine cells expressing the bHLH transcription factor Dimmed in Drosophila.

    Directory of Open Access Journals (Sweden)

    Jiangnan Luo

    Full Text Available Neurons and other cells display a large variation in size in an organism. Thus, a fundamental question is how growth of individual cells and their organelles is regulated. Is size scaling of individual neurons regulated post-mitotically, independent of growth of the entire CNS? Although the role of insulin/IGF-signaling (IIS in growth of tissues and whole organisms is well established, it is not known whether it regulates the size of individual neurons. We therefore studied the role of IIS in the size scaling of neurons in the Drosophila CNS. By targeted genetic manipulations of insulin receptor (dInR expression in a variety of neuron types we demonstrate that the cell size is affected only in neuroendocrine cells specified by the bHLH transcription factor DIMMED (DIMM. Several populations of DIMM-positive neurons tested displayed enlarged cell bodies after overexpression of the dInR, as well as PI3 kinase and Akt1 (protein kinase B, whereas DIMM-negative neurons did not respond to dInR manipulations. Knockdown of these components produce the opposite phenotype. Increased growth can also be induced by targeted overexpression of nutrient-dependent TOR (target of rapamycin signaling components, such as Rheb (small GTPase, TOR and S6K (S6 kinase. After Dimm-knockdown in neuroendocrine cells manipulations of dInR expression have significantly less effects on cell size. We also show that dInR expression in neuroendocrine cells can be altered by up or down-regulation of Dimm. This novel dInR-regulated size scaling is seen during postembryonic development, continues in the aging adult and is diet dependent. The increase in cell size includes cell body, axon terminations, nucleus and Golgi apparatus. We suggest that the dInR-mediated scaling of neuroendocrine cells is part of a plasticity that adapts the secretory capacity to changing physiological conditions and nutrient-dependent organismal growth.

  1. Effect of Salinity on the Composition, Number and Size of Epidermal Cells along the Mature Blade of Wheat Leaves

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Salinity inhibits leaf growth in association with changes in cell size. The objective of this study was to determine the spatial distributions of the composition, number and dimensions of epidermal cells in the mature blades of leaf four of wheat seedlings under saline conditions. Plants were grown in loamy soil either with or without 120 mmol/L NaCl in a growth chamber, and harvested after leaf four was fully developed. The results of the spatial distribution analyses of width along the blade showed that salinity not only reduced the width of the leaf blade, but that it also altered the distribution pattern of blade width along the leaf axis. The reduction in the final size of the leaf blade was associated with a reduction in the total number of epidermal cells and in their widths and lengths. This study also revealed the spatial effects of salinity on the blade and epidermal cell dimensions along the leaf axis. In particular, salinity inhibited the total cell number for interstomatal, sister and elongated cells, implying that cell division in wheat leaves is inhibited by salinity. However, the lengths of interstomatal cells were not affected by salinity (unlike those for the sister and elongated cells), suggesting the relative contributions of cell length and numbers to the reduction in the final length of the blade under salinity is dependent on cell type.

  2. Enhanced magnetic resonance imaging and staining of cancer cells using ferrimagnetic H-ferritin nanoparticles with increasing core size

    Science.gov (United States)

    Cai, Yao; Cao, Changqian; He, Xiaoqing; Yang, Caiyun; Tian, Lanxiang; Zhu, Rixiang; Pan, Yongxin

    2015-01-01

    Purpose This study is to demonstrate the nanoscale size effect of ferrimagnetic H-ferritin (M-HFn) nanoparticles on magnetic properties, relaxivity, enzyme mimetic activities, and application in magnetic resonance imaging (MRI) and immunohistochemical staining of cancer cells. Materials and methods M-HFn nanoparticles with different sizes of magnetite cores in the range of 2.7–5.3 nm were synthesized through loading different amounts of iron into recombinant human H chain ferritin (HFn) shells. Core size, crystallinity, and magnetic properties of those M-HFn nanoparticles were analyzed by transmission electron microscope and low-temperature magnetic measurements. The MDA-MB-231 cancer cells were incubated with synthesized M-HFn nanoparticles for 24 hours in Dulbecco’s Modified Eagle’s Medium. In vitro MRI of cell pellets after M-HFn labeling was performed at 7 T. Iron uptake of cells was analyzed by Prussian blue staining and inductively coupled plasma mass spectrometry. Immunohistochemical staining by using the peroxidase-like activity of M-HFn nanoparticles was carried out on MDA-MB-231 tumor tissue paraffin sections. Results The saturation magnetization (Ms), relaxivity, and peroxidase-like activity of synthesized M-HFn nanoparticles were monotonously increased with the size of ferrimagnetic cores. The M-HFn nanoparticles with the largest core size of 5.3 nm exhibit the strongest saturation magnetization, the highest peroxidase activity in immunohistochemical staining, and the highest r2 of 321 mM−1 s−1, allowing to detect MDA-MB-231 breast cancer cells as low as 104 cells mL−1. Conclusion The magnetic properties, relaxivity, and peroxidase-like activity of M-HFn nanoparticles are size dependent, which indicates that M-HFn nanoparticles with larger magnetite core can significantly enhance performance in MRI and staining of cancer cells. PMID:25878496

  3. Reduced salivary gland size and increased presence of epithelial progenitor cells in DLK1-deficient mice.

    Science.gov (United States)

    García-Gallastegui, P; Luzuriaga, J; Aurrekoetxea, M; Baladrón, V; Ruiz-Hidalgo, M J; García-Ramírez, J J; Laborda, J; Unda, F; Ibarretxe, G

    2016-06-01

    DLK1 (PREF1, pG2, or FA1) is a transmembrane and secreted protein containing epidermal growth factor-like repeats. Dlk1 expression is abundant in many tissues during embryonic and fetal development and is believed to play an important role in the regulation of tissue differentiation and fetal growth. After birth, Dlk1 expression is abolished in most tissues but is possibly reactivated to regulate stem cell activation and responses to injury. We have recently reported that DLK1 regulates many aspects of salivary gland organogenesis. Here, we have extended our studies of the salivary gland phenotype of Dlk1 knock-out mice. We have observed that salivary glands are smaller and weigh significantly less in both Dlk1 knock-out males and females compared with gender and age-matched wild-type mice and regardless of the natural sexual dimorphism in rodent salivary glands. This reduced size correlates with a reduced capacity of Dlk1-deficient mice to secrete saliva after stimulation with pilocarpine. However, histological and ultrastructural analyses of both adult and developing salivary gland tissues have revealed no defects in Dlk1 ((-/-)) mice, indicating that genetic compensation accounts for the relatively mild salivary phenotype in these animals. Finally, despite their lack of severe anomalies, we have found that salivary glands from Dlk1-deficient mice present a higher amount of CK14-positive epithelial progenitors at various developmental stages, suggesting a role for DLK1 in the regulation of salivary epithelial stem cell balance. PMID:26711912

  4. Regulation of lipid droplet size in mammary epithelial cells by remodeling of membrane lipid composition-a potential mechanism.

    Directory of Open Access Journals (Sweden)

    Bat-Chen Cohen

    Full Text Available Milk fat globule size is determined by the size of its precursors-intracellular lipid droplets-and is tightly associated with its composition. We examined the relationship between phospholipid composition of mammary epithelial cells and the size of both intracellular and secreted milk fat globules. Primary culture of mammary epithelial cells was cultured in medium without free fatty acids (control or with 0.1 mM free capric, palmitic or oleic acid for 24 h. The amount and composition of the cellular lipids and the size of the lipid droplets were determined in the cells and medium. Mitochondrial quantity and expression levels of genes associated with mitochondrial biogenesis and polar lipid composition were determined. Cells cultured with oleic and palmitic acids contained similar quantities of triglycerides, 3.1- and 3.8-fold higher than in controls, respectively (P 3 μm and phosphatidylethanolamine concentration was higher by 23 and 63% compared with that in the control and palmitic acid treatments, respectively (P < 0.0001. In the presence of palmitic acid, only 4% of the cells contained large lipid droplets and the membrane phosphatidylcholine concentration was 22% and 16% higher than that in the control and oleic acid treatments, respectively (P < 0.0001. In the oleic acid treatment, approximately 40% of the lipid droplets were larger than 5 μm whereas in that of the palmitic acid treatment, only 16% of the droplets were in this size range. Triglyceride secretion in the oleic acid treatment was 2- and 12-fold higher compared with that in the palmitic acid and control treatments, respectively. Results imply that membrane composition of bovine mammary epithelial cells plays a role in controlling intracellular and secreted lipid droplets size, and that this process is not associated with cellular triglyceride content.

  5. Selective self-assembly of adenine-silver nanoparticles forms rings resembling the size of cells

    Science.gov (United States)

    Choi, Sungmoon; Park, Soonyoung; Yang, Seon-Ah; Jeong, Yujin; Yu, Junhua

    2015-12-01

    Self-assembly has played critical roles in the construction of functional nanomaterials. However, the structure of the macroscale multicomponent materials built by the self-assembly of nanoscale building blocks is hard to predict due to multiple intermolecular interactions of great complexity. Evaporation of solvents is usually an important approach to induce kinetically stable assemblies of building blocks with a large-scale specific arrangement. During such a deweting process, we tried to monitor the possible interactions between silver nanoparticles and nucleobases at a larger scale by epifluorescence microscopy, thanks to the doping of silver nanoparticles with luminescent silver nanodots. ssDNA oligomer-stabilized silver nanoparticles and adenine self-assemble to form ring-like compartments similar to the size of modern cells. However, the silver ions only dismantle the self-assembly of adenine. The rings are thermodynamically stable as the drying process only enrich the nanoparticles-nucleobase mixture to a concentration that activates the self-assembly. The permeable membrane-like edge of the ring is composed of adenine filaments glued together by silver nanoparticles. Interestingly, chemicals are partially confined and accumulated inside the ring, suggesting that this might be used as a microreactor to speed up chemical reactions during a dewetting process.

  6. Conditioned medium from human amniotic mesenchymal stromal cells limits infarct size and enhances angiogenesis.

    Science.gov (United States)

    Danieli, Patrizia; Malpasso, Giuseppe; Ciuffreda, Maria Chiara; Cervio, Elisabetta; Calvillo, Laura; Copes, Francesco; Pisano, Federica; Mura, Manuela; Kleijn, Lennaert; de Boer, Rudolf A; Viarengo, Gianluca; Rosti, Vittorio; Spinillo, Arsenio; Roccio, Marianna; Gnecchi, Massimiliano

    2015-05-01

    The paracrine properties of human amniotic membrane-derived mesenchymal stromal cells (hAMCs) have not been fully elucidated. The goal of the present study was to elucidate whether hAMCs can exert beneficial paracrine effects on infarcted rat hearts, in particular through cardioprotection and angiogenesis. Moreover, we aimed to identify the putative active paracrine mediators. hAMCs were isolated, expanded, and characterized. In vitro, conditioned medium from hAMC (hAMC-CM) exhibited cytoprotective and proangiogenic properties. In vivo, injection of hAMC-CM into infarcted rat hearts limited the infarct size, reduced cardiomyocyte apoptosis and ventricular remodeling, and strongly promoted capillary formation at the infarct border zone. Gene array analysis led to the identification of 32 genes encoding for the secreted factors overexpressed by hAMCs. Among these, midkine and secreted protein acidic and rich in cysteine were also upregulated at the protein level. Furthermore, high amounts of several proangiogenic factors were detected in hAMC-CM by cytokine array. Our results strongly support the concept that the administration of hAMC-CM favors the repair process after acute myocardial infarction. PMID:25824141

  7. TUNING OF SIZE AND SHAPE OF AU-PT NANOCATALYST FOR DIRECT METHANOL FUEL CELLS

    Energy Technology Data Exchange (ETDEWEB)

    Murph, S.

    2011-04-20

    In this paper, we report the precise control of the size, shape and surface morphology of Au-Pt nanocatalysts (cubes, blocks, octahedrons and dogbones) synthesized via a seed-mediated approach. Gold 'seeds' of different aspect ratios (1 to 4.2), grown by a silver-assisted approach, were used as templates for high-yield production of novel Au-Pt nanocatalysts at a low temperature (40 C). Characterization by electron microscopy (SEM, TEM, HRTEM), energy dispersive X-ray analysis (EDX), UV-Vis spectroscopy, zeta-potential (surface charge), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometry (ICP-MS) were used to better understand their physico-chemical properties, preferred reactivities and underlying nanoparticle growth mechanism. A rotating disk electrode was used to evaluate the Au-Pt nanocatalysts electrochemical performance in the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) of direct methanol fuel cells. The results indicate the Au-Pt dogbones are partially and in some cases completely unaffected by methanol poisoning during the evaluation of the ORR. The ORR performance of the octahedron particles in the absence of MeOH is superior to that of the Au-Pt dogbones and Pt-black, however its performance is affected by the presence of MeOH.

  8. Using cathode spacers to minimize reactor size in air cathode microbial fuel cells

    KAUST Repository

    Yang, Qiao

    2012-04-01

    Scaling up microbial fuel cells (MFCs) will require more compact reactor designs. Spacers can be used to minimize the reactor size without adversely affecting performance. A single 1.5mm expanded plastic spacer (S1.5) produced a maximum power density (973±26mWm -2) that was similar to that of an MFC with the cathode exposed directly to air (no spacer). However, a very thin spacer (1.3mm) reduced power by 33%. Completely covering the air cathode with a solid plate did not eliminate power generation, indicating oxygen leakage into the reactor. The S1.5 spacer slightly increased columbic efficiencies (from 20% to 24%) as a result of reduced oxygen transfer into the system. Based on operating conditions (1000ς, CE=20%), it was estimated that 0.9Lh -1 of air would be needed for 1m 2 of cathode area suggesting active air flow may be needed for larger scale MFCs. © 2012 Elsevier Ltd.

  9. Size Matters: Molecular Weight Specificity of Hyaluronan Effects in Cell Biology

    OpenAIRE

    Jaime M. Cyphert; Trempus, Carol S.; Stavros Garantziotis

    2015-01-01

    Hyaluronan signaling properties are unique among other biologically active molecules, that they are apparently not influenced by postsynthetic molecular modification, but by hyaluronan fragment size. This review summarizes the current knowledge about the generation of hyaluronan fragments of different size and size-dependent differences in hyaluronan signaling as well as their downstream biological effects.

  10. Particle-in-cell simulations of the critical ionization velocity effect in finite size clouds

    Science.gov (United States)

    Moghaddam-Taaheri, E.; Lu, G.; Goertz, C. K.; Nishikawa, K. - I.

    1994-01-01

    The critical ionization velocity (CIV) mechanism in a finite size cloud is studied with a series of electrostatic particle-in-cell simulations. It is observed that an initial seed ionization, produced by non-CIV mechanisms, generates a cross-field ion beam which excites a modified beam-plasma instability (MBPI) with frequency in the range of the lower hybrid frequency. The excited waves accelerate electrons along the magnetic field up to the ion drift energy that exceeds the ionization energy of the neutral atoms. The heated electrons in turn enhance the ion beam by electron-neutral impact ionization, which establishes a positive feedback loop in maintaining the CIV process. It is also found that the efficiency of the CIV mechanism depends on the finite size of the gas cloud in the following ways: (1) Along the ambient magnetic field the finite size of the cloud, L (sub parallel), restricts the growth of the fastest growing mode, with a wavelength lambda (sub m parallel), of the MBPI. The parallel electron heating at wave saturation scales approximately as (L (sub parallel)/lambda (sub m parallel)) (exp 1/2); (2) Momentum coupling between the cloud and the ambient plasma via the Alfven waves occurs as a result of the finite size of the cloud in the direction perpendicular to both the ambient magnetic field and the neutral drift. This reduces exponentially with time the relative drift between the ambient plasma and the neutrals. The timescale is inversely proportional to the Alfven velocity. (3) The transvers e charge separation field across the cloud was found to result in the modulation of the beam velocity which reduces the parallel heating of electrons and increases the transverse acceleration of electrons. (4) Some energetic electrons are lost from the cloud along the magnetic field at a rate characterized by the acoustic velocity, instead of the electron thermal velocity. The loss of energetic electrons from the cloud seems to be larger in the direction of

  11. Optimal sizing of plug-in fuel cell electric vehicles using models of vehicle performance and system cost

    International Nuclear Information System (INIS)

    Highlights: ► An analytical model for vehicle performance and power-train parameters. ► Quantitative relationships between vehicle performance and power-train parameters. ► Optimal sizing rules that help designing an optimal PEM fuel cell power-train. ► An on-road testing showing the performance of the proposed vehicle. -- Abstract: This paper presents an optimal sizing method for plug-in proton exchange membrane (PEM) fuel cell and lithium-ion battery (LIB) powered city buses. We propose a theoretical model describing the relationship between components’ parameters and vehicle performance. Analysis results show that within the working range of the electric motor, the maximal velocity and driving distance are influenced linearly by the parameters of the components, e.g. fuel cell efficiency, fuel cell output power, stored hydrogen mass, vehicle auxiliary power, battery capacity, and battery average resistance. Moreover, accelerating time is also linearly dependant on the abovementioned parameters, except of those of the battery. Next, we attempt to minimize fixed and operating costs by introducing an optimal sizing problem that uses as constraints the requirements on vehicle performance. By solving this problem, we attain several optimal sizing rules. Finally, we use these rules to design a plug-in PEM fuel cell city bus and present performance results obtained by on-road testing.

  12. A Systematic Analysis of Cell Cycle Regulators in Yeast Reveals That Most Factors Act Independently of Cell Size to Control Initiation of Division

    OpenAIRE

    Scott A Hoose; Jeremy A Rawlings; Kelly, Michelle M.; M Camille Leitch; Ababneh, Qotaiba O; Robles, Juan P.; David Taylor; Hoover, Evelyn M.; Bethel Hailu; McEnery, Kayla A.; S Sabina Downing; Deepika Kaushal; Yi Chen; Alex Rife; Kirtan A Brahmbhatt

    2012-01-01

    Upstream events that trigger initiation of cell division, at a point called START in yeast, determine the overall rates of cell proliferation. The identity and complete sequence of those events remain unknown. Previous studies relied mainly on cell size changes to identify systematically genes required for the timely completion of START. Here, we evaluated panels of non-essential single gene deletion strains for altered DNA content by flow cytometry. This analysis revealed that most gene dele...

  13. Enhancing the grain size of organic halide perovskites by sulfonate-carbon nanotube incorporation in high performance perovskite solar cells.

    Science.gov (United States)

    Zhang, Yong; Tan, Licheng; Fu, Qingxia; Chen, Lie; Ji, Ting; Hu, Xiaotian; Chen, Yiwang

    2016-04-14

    The grain size of perovskites was enhanced and the grain boundary was filled with sulfonate carbon nanotubes (s-CNTs) during the CH3NH3PbI3 perovskite precursor solution spin-coating process with the incorporation of s-CNTs. The performance of s-CNT incorporated perovskite solar cells remarkably increased from 10.3% to 15.1% (best) compared with pristine CNT incorporated perovskite solar cells. PMID:26940646

  14. A systematic analysis of cell cycle regulators in yeast reveals that most factors act independently of cell size to control initiation of division.

    Directory of Open Access Journals (Sweden)

    Scott A Hoose

    Full Text Available Upstream events that trigger initiation of cell division, at a point called START in yeast, determine the overall rates of cell proliferation. The identity and complete sequence of those events remain unknown. Previous studies relied mainly on cell size changes to identify systematically genes required for the timely completion of START. Here, we evaluated panels of non-essential single gene deletion strains for altered DNA content by flow cytometry. This analysis revealed that most gene deletions that altered cell cycle progression did not change cell size. Our results highlight a strong requirement for ribosomal biogenesis and protein synthesis for initiation of cell division. We also identified numerous factors that have not been previously implicated in cell cycle control mechanisms. We found that CBS, which catalyzes the synthesis of cystathionine from serine and homocysteine, advances START in two ways: by promoting cell growth, which requires CBS's catalytic activity, and by a separate function, which does not require CBS's catalytic activity. CBS defects cause disease in humans, and in animals CBS has vital, non-catalytic, unknown roles. Hence, our results may be relevant for human biology. Taken together, these findings significantly expand the range of factors required for the timely initiation of cell division. The systematic identification of non-essential regulators of cell division we describe will be a valuable resource for analysis of cell cycle progression in yeast and other organisms.

  15. Size-mediated cytotoxicity of nanocrystalline titanium dioxide, pure and zinc-doped hydroxyapatite nanoparticles in human hepatoma cells

    International Nuclear Information System (INIS)

    Nanoparticles are highly used in biological applications including nanomedicine. In this present study, the interaction of HepG2 hepatocellular carcinoma cells (HCC) with hydroxyapatite (HAp), zinc-doped hydroxyapatite, and titanium dioxide (TiO2) nanoparticles were investigated. Hydroxyapatite, zinc-doped hydroxyapatite and titanium dioxide nanoparticles were prepared by wet precipitation method. They were subjected to isochronal annealing at different temperatures. Particle morphology and size distribution were characterized by X-ray diffraction and transmission electron microscope. The nanoparticles were co-cultured with HepG2 cells. MTT assay was employed to evaluate the proliferation of tumor cells. The DNA damaging effect of HAp, Zn-doped HAp, and TiO2 nanoparticles in human hepatoma cells (HepG2) were evaluated using DNA fragmentation studies. The results showed that in HepG2 cells, the anti-tumor activity strongly depend on the size of nanoparticles in HCC cells. Cell cycle arrest analysis for HAp, zinc-doped HAp, and TiO2 nanoparticles revealed the influence of HAp, zinc-doped HAp, and titanium dioxide nanoparticles on the apoptosis of HepG2 cells. The results imply that the novel nano nature effect plays an important role in the biomedicinal application of nanoparticles.

  16. Large Size Cells in the Visceral Adipose Depot Predict Insulin Resistance in the Canine Model

    OpenAIRE

    Kabir, Morvarid; Stefanovski, Darko; Hsu, Isabel R.; Iyer, Malini; Woolcott, Orison O.; Zheng, Dan; Catalano, Karyn J.; Chiu, Jenny D.; Kim, Stella P.; Lisa N Harrison; Ionut, Viorica; Lottati, Maya; Richard N Bergman; Richey, Joyce M.

    2011-01-01

    Adipocyte size plays a key role in the development of insulin resistance. We examined longitudinal changes in adipocyte size and distribution in visceral (VIS) and subcutaneous (SQ) fat during obesity-induced insulin resistance and after treatment with CB-1 receptor antagonist, rimonabant (RIM) in canines. We also examined whether adipocyte size and/or distribution is predictive of insulin resistance. Adipocyte morphology was assessed by direct microscopy and analysis of digital images in pre...

  17. Constant phycobilisome size in chromatically adapted cells of the cyanobacterium Tolypothrix tenuis, and variation in Nostoc sp

    Energy Technology Data Exchange (ETDEWEB)

    Ohki, K.; Gantt, E.; Lipschultz, C.A.; Ernst, M.C.

    1985-12-01

    Phycobilisomes of Tolypothrix tenuis, a cyanobacterium capable of complete chromatic adaptation, were studied from cells grown in red and green light, and in darkness. The phycobilisome size remained constant irrespective of the light quality. The hemidiscoidal phycobilisomes had an average diameter of about 52 nanometers and height of about 33 nanometers, by negative staining. The thickness was equivalent to a physocyanin molecule (about 10 nanometers). The molar ratio of allophycocyanin, relative to other phycobiliproteins always remained at about 1:3. Phycobilisomes from red light grown cells and cells grown heterotrophically in darkness were indistinguishable in their pigment composition, polypeptide pattern, and size. Eight polypeptides were resolved in the phycobilin region (17.5 to 23.5 kilodaltons) by isoelectric focusing followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Half of these were invariable, while others were variable in green and red light. It is inferred that phycoerythrin synthesis in green light resulted in a one for one substitution of phycocyanin, thus retaining a constant phycobilisome size. Tolypothrix appears to be one of the best examples of phycobiliprotein regulation with wavelength. By contrast, in Nostoc sp., the decrease in phycoerythrin in red light cells was accompanied by a decrease in phycobilisome size but not a regulated substitution.

  18. Real-time garbage collection for list processing using restructured cells for increased reference counter size

    Science.gov (United States)

    Shuler, Jr., Robert L. (Inventor)

    1990-01-01

    In a list processing system, small reference counters are maintained in conjunction with memory cells for the purpose of identifying memory cells that become available for re-use. The counters are updated as references to the cells are created and destroyed, and when a counter of a cell is decremented to logical zero the cell is immediately returned to a list of free cells. In those cases where a counter must be incremented beyond the maximum value that can be represented in a small counter, the cell is restructured so that the additional reference count can be represented. The restructuring involves allocating an additional cell, distributing counter, tag, and pointer information among the two cells, and linking both cells appropriately into the existing list structure.

  19. Cell number regulator genes in Prunus provide candidate genes for the control of fruit size in sweet and sour cherry.

    Science.gov (United States)

    De Franceschi, P; Stegmeir, T; Cabrera, A; van der Knaap, E; Rosyara, U R; Sebolt, A M; Dondini, L; Dirlewanger, E; Quero-Garcia, J; Campoy, J A; Iezzoni, A F

    2013-01-01

    Striking increases in fruit size distinguish cultivated descendants from small-fruited wild progenitors for fleshy fruited species such as Solanum lycopersicum (tomato) and Prunus spp. (peach, cherry, plum, and apricot). The first fruit weight gene identified as a result of domestication and selection was the tomato FW2.2 gene. Members of the FW2.2 gene family in corn (Zea mays) have been named CNR (Cell Number Regulator) and two of them exert their effect on organ size by modulating cell number. Due to the critical roles of FW2.2/CNR genes in regulating cell number and organ size, this family provides an excellent source of candidates for fruit size genes in other domesticated species, such as those found in the Prunus genus. A total of 23 FW2.2/CNR family members were identified in the peach genome, spanning the eight Prunus chromosomes. Two of these CNRs were located within confidence intervals of major quantitative trait loci (QTL) previously discovered on linkage groups 2 and 6 in sweet cherry (Prunus avium), named PavCNR12 and PavCNR20, respectively. An analysis of haplotype, sequence, segregation and association with fruit size strongly supports a role of PavCNR12 in the sweet cherry linkage group 2 fruit size QTL, and this QTL is also likely present in sour cherry (P. cerasus). The finding that the increase in fleshy fruit size in both tomato and cherry associated with domestication may be due to changes in members of a common ancestral gene family supports the notion that similar phenotypic changes exhibited by independently domesticated taxa may have a common genetic basis. PMID:23976873

  20. Overexpression of PhEXPA1 increases cell size, modifies cell wall polymer composition and affects the timing of axillary meristem development in Petunia hybrida.

    Science.gov (United States)

    Zenoni, Sara; Fasoli, Marianna; Tornielli, Giovanni Battista; Dal Santo, Silvia; Sanson, Andrea; de Groot, Peter; Sordo, Sara; Citterio, Sandra; Monti, Francesca; Pezzotti, Mario

    2011-08-01

    • Expansins are cell wall proteins required for cell enlargement and cell wall loosening during many developmental processes. The involvement of the Petunia hybrida expansin A1 (PhEXPA1) gene in cell expansion, the control of organ size and cell wall polysaccharide composition was investigated by overexpressing PhEXPA1 in petunia plants. • PhEXPA1 promoter activity was evaluated using a promoter-GUS assay and the protein's subcellular localization was established by expressing a PhEXPA1-GFP fusion protein. PhEXPA1 was overexpressed in transgenic plants using the cauliflower mosaic virus (CaMV) 35S promoter. Fourier transform infrared (FTIR) and chemical analysis were used for the quantitative analysis of cell wall polymers. • The GUS and GFP assays demonstrated that PhEXPA1 is present in the cell walls of expanding tissues. The constitutive overexpression of PhEXPA1 significantly affected expansin activity and organ size, leading to changes in the architecture of petunia plants by initiating premature axillary meristem outgrowth. Moreover, a significant change in cell wall polymer composition in the petal limbs of transgenic plants was observed. • These results support a role for expansins in the determination of organ shape, in lateral branching, and in the variation of cell wall polymer composition, probably reflecting a complex role in cell wall metabolism. PMID:21534969

  1. Enhanced magnetic resonance imaging and staining of cancer cells using ferrimagnetic H-ferritin nanoparticles with increasing core size

    Directory of Open Access Journals (Sweden)

    Cai Y

    2015-04-01

    Full Text Available Yao Cai,1–3 Changqian Cao,1,2 Xiaoqing He,1 Caiyun Yang,1–3 Lanxiang Tian,1,2 Rixiang Zhu,2 Yongxin Pan1,21France–China Bio-Mineralization and Nano-Structures Laboratory, 2Paleomagnetism and Geochronology Laboratory, Key Laboratory of the Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, 3University of Chinese Academy of Sciences, Beijing, People’s Republic of ChinaPurpose: This study is to demonstrate the nanoscale size effect of ferrimagnetic H-ferritin (M-HFn nanoparticles on magnetic properties, relaxivity, enzyme mimetic activities, and application in magnetic resonance imaging (MRI and immunohistochemical staining of cancer cells.Materials and methods: M-HFn nanoparticles with different sizes of magnetite cores in the range of 2.7–5.3 nm were synthesized through loading different amounts of iron into recombinant human H chain ferritin (HFn shells. Core size, crystallinity, and magnetic properties of those M-HFn nanoparticles were analyzed by transmission electron microscope and low-temperature magnetic measurements. The MDA-MB-231 cancer cells were incubated with synthesized M-HFn nanoparticles for 24 hours in Dulbecco’s Modified Eagle’s Medium. In vitro MRI of cell pellets after M-HFn labeling was performed at 7 T. Iron uptake of cells was analyzed by Prussian blue staining and inductively coupled plasma mass spectrometry. Immunohistochemical staining by using the peroxidase-like activity of M-HFn nanoparticles was carried out on MDA-MB-231 tumor tissue paraffin sections.Results: The saturation magnetization (Ms, relaxivity, and peroxidase-like activity of synthesized M-HFn nanoparticles were monotonously increased with the size of ferrimagnetic cores. The M-HFn nanoparticles with the largest core size of 5.3 nm exhibit the strongest saturation magnetization, the highest peroxidase activity in immunohistochemical staining, and the highest r2 of 321 mM-1 s-1, allowing to

  2. Crambescidin-816 Acts as a Fungicidal with More Potency than Crambescidin-800 and -830, Inducing Cell Cycle Arrest, Increased Cell Size and Apoptosis in Saccharomyces cerevisiae

    OpenAIRE

    Vega, Félix V.; Vieytes, Mercedes R.; Botana, Luis M; Thomas, Olivier P.; Henar López-Alonso; Rubiolo, Juan A.; Eva Ternon

    2013-01-01

    In this paper, we show the effect of crambescidin-816, -800, and -830 on Saccharomyces cerevisiae viability. We determined that, of the three molecules tested, crambescidin-816 was the most potent. Based on this result, we continued by determining the effect of crambescidin-816 on the cell cycle of this yeast. The compound induced cell cycle arrest in G2/M followed by an increase in cell DNA content and size. When the type of cell death was analyzed, we observed that crambescidin-816 induced ...

  3. Lipid droplets characterization in adipocyte differentiated 3T3-L1 cells: size and optical density distribution

    Directory of Open Access Journals (Sweden)

    V. Rizzatti

    2013-08-01

    Full Text Available The 3T3-L1 cell line, derived from 3T3 cells, is widely used in biological research on adipose tissue. 3T3-L1 cells have a fibroblast-like morphology, but, under appropriate conditions, they differentiate into an adipocyte-like phenotype. During the differentiation process, 3T3-L1 cells increase the synthesis of triglycerides and acquire the behavior of adipose cells. In particular, triglycerides accumulate in lipid droplets (LDs embedded in the cytoplasm. The number and the size distribution of the LDs is often correlated with obesity and many other pathologies linked with fat accumulation. The integrated optical density (IOD of the LDs is related with the amount of triglycerides in the droplets. The aim of this study is the attempt to characterize the size distribution and the IOD of the LDs in 3T3-L1 differentiated cells. The cells were differentiated into adipocytes for 5 days with a standard procedure, stained with Oil Red O and observed with an optical microscope. The diameter, area, optical density of the LDs were measured. We found an asymmetry of the kernel density distribution of the maximum Feret’s diameter of the LDs with a tail due to very large LDs. More information regarding the birth of the LDs could help in finding the best mathematical model in order to analyze fat accumulation in adipocytes.

  4. TCR-dependent differentiation of thymic Foxp3+ cells is limited to small clonal sizes

    OpenAIRE

    Leung, Monica W.L.; Shen, Shiqian; Lafaille, Juan J.

    2009-01-01

    Numerous studies have highlighted the importance of high-affinity interactions between T cell receptors (TCRs) and their ligands in the selection of Foxp3+ regulatory T cells (T reg cells). To determine the role of the TCR in directing T cells into the Foxp3+ lineage, we generated transgenic (Tg) mice expressing TCRs from Foxp3+ cells. Initial analyses of the TCR Tg mice crossed with RAG-deficient mice showed that the percentage of Foxp3+ cells was very low. However, intrathymic injection and...

  5. Effect of selenium nanoparticles with different sizes in primary cultured intestinal epithelial cells of crucian carp, Carassius auratus gibelio

    Directory of Open Access Journals (Sweden)

    Wang YB

    2013-10-01

    Full Text Available Yanbo Wang, Xuxia Yan, Linglin Fu Marine Resources and Nutrition Biology Research Center, Food Quality and Safety Department, Zhejiang Gongshang University, Hangzhou, People's Republic of China Abstract: Nano-selenium (Se, with its high bioavailability and low toxicity, has attracted wide attention for its potential application in the prevention of oxidative damage in animal tissues. However, the effect of nano-Se of different sizes on the intestinal epithelial cells of the crucian carp (Carassius auratus gibelio is poorly understood. Our study showed that different sizes and doses of nano-Se have varied effects on the cellular protein contents and the enzyme activities of secreted lactate dehydrogenase, intracellular sodium potassium adenosine triphosphatase, glutathione peroxidase, and superoxide dismutase. It was also indicated that nano-Se had a size-dependent effect on the primary intestinal epithelial cells of the crucian carp. Thus, these findings may bring us a step closer to understanding the size effect and the bioavailability of nano-Se on the intestinal tract of the crucian carp. Keywords: selenium nanoparticle, intestinal epithelial cell, crucian carp, primary culture

  6. Evidence for P-Glycoprotein Involvement in Cell Volume Regulation Using Coulter Sizing in Flow Cytometry

    Directory of Open Access Journals (Sweden)

    Jennifer Pasquier

    2015-06-01

    Full Text Available The regulation of cell volume is an essential function that is coupled to a variety of physiological processes such as receptor recycling, excitability and contraction, cell proliferation, migration, and programmed cell death. Under stress, cells undergo emergency swelling and respond to such a phenomenon with a regulatory volume decrease (RVD where they release cellular ions, and other osmolytes as well as a concomitant loss of water. The link between P-glycoprotein, a transmembrane transporter, and cell volume regulation is controversial, and changes in cells volume are measured using microscopy or electrophysiology. For instance, by using the patch-clamp method, our team demonstrated that chloride currents activated in the RVD were more intense and rapid in a breast cancer cell line overexpressing the P-glycoprotein (P-gp. The Cell Lab Quanta SC is a flow cytometry system that simultaneously measures electronic volume, side scatter and three fluorescent colors; altogether this provides unsurpassed population resolution and accurate cell counting. Therefore, here we propose a novel method to follow cellular volume. By using the Coulter-type channel of the cytometer Cell Lab Quanta SC MPL (multi-platform loading, we demonstrated a role for the P-gp during different osmotic treatments, but also a differential activity of the P-gp through the cell cycle. Altogether, our data strongly suggests a role of P-gp in cell volume regulation.

  7. Comparison of Cell Viability and Embryoid Body Size of Two Embryonic Stem Cell Lines After Different Exposure Times to Bone Morphogenetic Protein 4

    Directory of Open Access Journals (Sweden)

    Nehleh Zarei Fard

    2015-03-01

    Full Text Available Background: Activation of bone morphogenetic protein 4 (BMP4 signaling pathway in embryonic stem (ES cells plays an important role in controlling cell proliferation, differentiation, and apoptosis. Adverse effects of BMP4 occur in a time dependent manner; however, little is known about the effect of different time exposure of this growth factor on cell number in culture media. In this study, we investigated the role of two different exposure times to BMP4 in cell viability, embryoid body (EB, size, and cavitation of ES cells. Methods: Embryonic stem cells (R1 and B1 lines were released from the feeder cell layers and were cultured using EBs protocol by using the hanging drop method and monolayer culture system. The cells were cultured for 5 days with 100 ng/mL BMP4 from the beginning (++BMP4 or after 48 h (+BMP4 of culture and their cell number were counted by trypan blue staining. The data were analyzed using non-parametric two-tailed Mann-Whitney test. P<0.05 was considered as significant. Results: In EB culture protocol, cell number significantly decreased in +BMP4 culture condition with greater cavity size compared to the ++BMP4 condition at day 5 (P=0.009. In contrast, in monolayer culture system, there was no significant difference in the cell number between all groups (P=0.91. Conclusion: The results suggest that short-term exposure of BMP4 is required to promote cavitation in EBs according to lower cell number in +BMP4 condition. Different cell lines showed different behavior in cavitation formation.

  8. Effect of size and structure of a bacteria fuel cell on the electricity production and energy conversion rate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xiachang; Halme, A.

    1997-12-31

    The direct conversion of chemical energy to electrical energy can be realized by using microorganisms as catalyst in a microbial fuel cell. A relative big size bacteria fuel cell is investigated and compared to a smaller one constructed and tested previously. The big cell consists of a anode chamber and two cathode chambers. A packed bed of graphite particles was used as the anode and an oxygen gas diffusion electrode was used as the cathode in both devices. The cation permeable ion-exchange membrane from DuPont was used to separate anodic and cathodic chambers. Batch and self-circulation operation modes were applied in both devices. The apparent anode volume of the bigger device is 145.3 ml which is 2.7 times of the smaller cell volume (53.3 ml). The purpose of this study is to know what size of a bacteria fuel cell is suitable for the fuel cell to obtain maximum power output per volume. (orig.) 18 refs.

  9. Cancerous epithelial cell lines shed extracellular vesicles with a bimodal size distribution that is sensitive to glutamine inhibition

    Science.gov (United States)

    Santana, Steven Michael; Antonyak, Marc A.; Cerione, Richard A.; Kirby, Brian J.

    2014-12-01

    Extracellular shed vesicles (ESVs) facilitate a unique mode of cell-cell communication wherein vesicle uptake can induce a change in the recipient cell's state. Despite the intensity of ESV research, currently reported data represent the bulk characterization of concentrated vesicle samples with little attention paid to heterogeneity. ESV populations likely represent diversity in mechanisms of formation, cargo and size. To better understand ESV subpopulations and the signaling cascades implicated in their formation, we characterize ESV size distributions to identify subpopulations in normal and cancerous epithelial cells. We have discovered that cancer cells exhibit bimodal ESV distributions, one small-diameter and another large-diameter population, suggesting that two mechanisms may govern ESV formation, an exosome population and a cancer-specific microvesicle population. Altered glutamine metabolism in cancer is thought to fuel cancer growth but may also support metastatic niche formation through microvesicle production. We describe the role of a glutaminase inhibitor, compound 968, in ESV production. We have discovered that inhibiting glutamine metabolism significantly impairs large-diameter microvesicle production in cancer cells.

  10. The size and conformation of Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) DNA in infected cells and virions.

    OpenAIRE

    Renne, R; Lagunoff, M; Zhong, W.; Ganem, D

    1996-01-01

    The genome of a novel human herpesvirus has been detected in specimens of Kaposi's sarcoma (KS) and in several AIDS-related lymphoproliferative disorders. Here we examine the size and genomic conformation of the DNA of this virus (known as KS-associated herpesvirus or human herpesvirus 8) in latently and lytically infected cells and in virions. Pulsed-field gel electrophoresis of viral DNA shows that the viral genome is similar in size to those of other gammaherpesviruses (160 to 170 kb). As ...

  11. Micro-/Nano- sized hydroxyapatite directs differentiation of rat bone marrow derived mesenchymal stem cells towards an osteoblast lineage

    Science.gov (United States)

    Huang, Yan; Zhou, Gang; Zheng, Lisha; Liu, Haifeng; Niu, Xufeng; Fan, Yubo

    2012-03-01

    Regenerative medicine consisting of cells and materials provides a new way for the repair and regeneration of tissues and organs. Nano-biomaterials are highlighted due to their advantageous features compared with conventional micro-materials. The aim of this study is to investigate the effects of micro-/nano- sized hydroxyapatite (μ/n-HA) on the osteogenic differentiation of rat bone marrow derived mesenchymal stem cells (rBMSCs). μ/n-HA were prepared by a microwave synthesizer and precipitation method, respectively. Different sizes of μ/n-HA were characterized by IR, XRD, SEM, TEM and co-cultured with rBMSCs. It was shown that rBMSCs expressed higher levels of osteoblast-related markers by n-HA than μ-HA stimulation. The size of HA is an important factor for affecting the osteogenic differentiation of rBMSCs. This provides a new avenue for mechanistic studies of stem cell differentiation and a new approach to obtain more committed differentiated cells.

  12. Hierarchical TiO2 submicron-sized spheres for enhanced power conversion efficiency in dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Hierarchical TiO2 submicron-sized sphere scattering layer, with relatively large surface area and effective light scattering, shows enhanced power conversion efficiency in dye-sensitized solar cells. - Highlights: • Hierarchical TiO2 submicron-sized spheres (TiO2 HSSs) with diameters of 400–600 nm were synthesized. • The HSSs composed of nanoparticles of ∼14 nm have a relatively large surface area of ∼35 m2/g. • DSC exhibited the highest cell efficiency (6.23%) compared with ones with pure P25 (5.50%) or HSS (2.00%) photoanodes. - Abstract: Hierarchical TiO2 submicron-sized spheres (TiO2 HSSs) with diameters of 400–600 nm were synthesized by a facile one-step solvothermal method in ethanol solvent. The HSSs composed of nanoparticles of ∼14 nm have a relatively large surface area of ∼35 m2/g. When applied as the scattering overlayer in dye-sensitized solar cells (DSCs), such TiO2 HSSs effectively improved light harvesting and led to the increase of photocurrent in DSCs. Furthermore, bilayer-structured photoanode also provided fast electron transportation and long electron lifetime as confirmed by electrochemical impedance spectra. As a result, DSC based on P25 nanoparticle underlayer and HSS-2 overlayer exhibited the highest cell efficiency (6.23%) compared with ones with pure P25 (5.50%) or HSS-2 (2.00%) photoanodes

  13. Cell culture arrays using micron-sized ferromagnetic ring-shaped thin films

    International Nuclear Information System (INIS)

    Cell patterning has become an important technology for tissue engineering. In this research, domain walls are formed at the two ends of a ferromagnetic ring thin film after applying a strong external magnetic field, which can effectively attract magnetically labeled cells and control the position for biological cell. Magnetophoresis experiment was conducted to quantify the magnetic nanoparticle inside the cells. A ring-shaped magnetic thin films array was fabricated through photolithography. It is observed that magnetically labeled cells can be successfully attracted to the two ends of the ring-shaped magnetic thin film structure and more cells were attracted and further attached to the structures. The cells are co-cultured with the structure and kept proliferating; therefore, such ring thin film can be an important candidate for in-vitro biomedical chips or tissue engineering

  14. Cell culture arrays using micron-sized ferromagnetic ring-shaped thin films

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chen-Yu; Wei, Zung-Hang, E-mail: wei@pme.nthu.edu.tw [Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu City 300, Taiwan (China); Lai, Mei-Feng; Ger, Tzong-Rong [Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu City 300, Taiwan (China)

    2015-05-07

    Cell patterning has become an important technology for tissue engineering. In this research, domain walls are formed at the two ends of a ferromagnetic ring thin film after applying a strong external magnetic field, which can effectively attract magnetically labeled cells and control the position for biological cell. Magnetophoresis experiment was conducted to quantify the magnetic nanoparticle inside the cells. A ring-shaped magnetic thin films array was fabricated through photolithography. It is observed that magnetically labeled cells can be successfully attracted to the two ends of the ring-shaped magnetic thin film structure and more cells were attracted and further attached to the structures. The cells are co-cultured with the structure and kept proliferating; therefore, such ring thin film can be an important candidate for in-vitro biomedical chips or tissue engineering.

  15. Plasmonic nanoparticle films for solar cell applications fabricated by size-selective aerosol deposition

    OpenAIRE

    Pfeiffer, T.V.; Ortiz Gonzalez, J.; Santbergen, R.; Tan, H.; Schmidt-Ott, A.; Zeman, M.; Smets, A.H.M.

    2014-01-01

    A soft deposition method for incorporating surface plasmon resonant metal nanoparticles within photovoltaic devices was studied. This self-assembly method provides excellent control over both nanoparticle size and surface coverage. Films of spherical Ag nanoparticles with diameter of ∼100 nm were fabricated by depositing size-selected aerosols on various substrates using electrophoresis. This novel deposition method opens the route to embed plasmonic nanoparticles in the intermediate reflecto...

  16. Cellular size as a means of tracking mTOR activity and cell fate of CD4+ T cells upon antigen recognition.

    Directory of Open Access Journals (Sweden)

    Kristen N Pollizzi

    Full Text Available mTOR is a central integrator of metabolic and immunological stimuli, dictating immune cell activation, proliferation and differentiation. In this study, we demonstrate that within a clonal population of activated T cells, there exist both mTORhi and mTORlo cells exhibiting highly divergent metabolic and immunologic functions. By taking advantage of the role of mTOR activation in controlling cellular size, we demonstrate that upon antigen recognition, mTORhi CD4+ T cells are destined to become highly glycolytic effector cells. Conversely, mTORlo T cells preferentially develop into long-lived cells that express high levels of Bcl-2, CD25, and CD62L. Furthermore, mTORlo T cells have a greater propensity to differentiate into suppressive Foxp3+ T regulatory cells, and this paradigm was also observed in human CD4+ T cells. Overall, these studies provide the opportunity to track the development of effector and memory T cells from naïve precursors, as well as facilitate the interrogation of immunologic and metabolic programs that inform these fates.

  17. Systematic analysis of embryonic stem cell differentiation in hydrodynamic environments with controlled embryoid body size

    OpenAIRE

    Kinney, Melissa A.; Saeed, Rabbia; McDevitt, Todd C.

    2012-01-01

    The sensitivity of stem cells to environmental perturbations has prompted many studies which aim to characterize the influence of mechanical factors on stem cell morphogenesis and differentiation. Hydrodynamic cultures, often employed for large scale bioprocessing applications, impart complex fluid shear and transport profiles, and influence cell fate as a result of changes in media mixing conditions. However, previous studies of hydrodynamic cultures have been limited in their ability to dis...

  18. Size and frequency of gaps in newly synthesized DNA of xeroderma pigmentosum human cells irradiated with ultraviolet light

    International Nuclear Information System (INIS)

    Native newly synthesized DNA from human cells (xeroderma pigmentosum type) irradiated with ultraviolet light releases short pieces of DNA (L-DNA) when incubated with the single-strand specific S1 nuclease. This is not observed in the case of unirradiated cells. Previous experiments had shown that the L-DNA resulted from the action of S1 nuclease upon gaps, i.e., single-stranded DNA discontinuities in larger pieces of double-stranded DNA. We verified that the duplex L-DNA, that arises from the inter-gap regions upon S1 nuclease treatment, has a size which approximates the distance between two pyrimidine dimers on the same strand. A method was devised to measure the size of the gaps. These parameters have been considered in the proposition of a model for DNA synthesis on a template containing pyrimidine dimers

  19. Cancerous epithelial cell lines shed extracellular vesicles with a bimodal size distribution that is sensitive to glutamine inhibition

    International Nuclear Information System (INIS)

    Extracellular shed vesicles (ESVs) facilitate a unique mode of cell–cell communication wherein vesicle uptake can induce a change in the recipient cell's state. Despite the intensity of ESV research, currently reported data represent the bulk characterization of concentrated vesicle samples with little attention paid to heterogeneity. ESV populations likely represent diversity in mechanisms of formation, cargo and size. To better understand ESV subpopulations and the signaling cascades implicated in their formation, we characterize ESV size distributions to identify subpopulations in normal and cancerous epithelial cells. We have discovered that cancer cells exhibit bimodal ESV distributions, one small-diameter and another large-diameter population, suggesting that two mechanisms may govern ESV formation, an exosome population and a cancer-specific microvesicle population. Altered glutamine metabolism in cancer is thought to fuel cancer growth but may also support metastatic niche formation through microvesicle production. We describe the role of a glutaminase inhibitor, compound 968, in ESV production. We have discovered that inhibiting glutamine metabolism significantly impairs large-diameter microvesicle production in cancer cells. (paper)

  20. Effects of Size-Fractionated Particulate Matter on Cellular Oxidant Radical Generation in Human Bronchial Epithelial BEAS-2B Cells

    OpenAIRE

    Longfei Guan; Wei Rui; Ru Bai; Wei Zhang; Fang Zhang; Wenjun Ding

    2016-01-01

    The aim of the present study was to investigate the effects of size-fractionated (i.e., <1; 1–2.5, and 2.5–10 µm in an aerodynamic diameter) ambient particulate matter (PM) on reactive oxygen species (ROS) activity and cell viability in human bronchial epithelial cells (BEAS-2B). The PM samples were collected from an urban site (uPM) in Beijing and a steel factory site (sPM) in Anshan, China, from March 2013 to December 2014. Metal elements, organic and elemental carbon, and water-soluble ...

  1. Fabrication and Characterization of a Perovskite-Type Solar Cell with a Substrate Size of 70 mm

    Directory of Open Access Journals (Sweden)

    Takeo Oku

    2015-10-01

    Full Text Available A perovskite-type solar cell with a substrate size of 70 mm × 70 mm was fabricated by a simple spin-coating method using a mixed solution. The photovoltaic properties of the TiO2/CH3NH3PbI3-based photovoltaic devices were investigated by current density-voltage characteristic and incident photon to current conversion efficiency measurements. Their short-circuit current densities were almost constant over a large area. The photoconversion efficiency was influenced by the open-circuit voltage, which depended on the distance from the center of the cell.

  2. The influence of electrospun fibre size on Schwann cell behaviour and axonal outgrowth

    International Nuclear Information System (INIS)

    Fibrous substrates functioning as temporary extracellular matrices can be prepared easily by electrospinning, yielding fibrous matrices suitable as internal fillers for nerve guidance channels. In this study, gelatin micro- or nano-fibres were prepared by electrospinning by tuning the gelatin concentration and solution flow rate. The effect of gelatin fibre diameter on cell adhesion and proliferation was tested in vitro using explant cultures of Schwann cells (SC) and dorsal root ganglia (DRG). Cell adhesion was assessed by quantifying the cell spreading area, actin cytoskeleton organization and focal adhesion complex formation. Nano-fibres promoted cell spreading and actin cytoskeleton organization, increasing cellular adhesion and the proliferation rate. However, both migration rate and motility, quantified by transwell and time lapse assays respectively, were greater in cells cultured on micro-fibres. Finally, there was more DRG axon outgrowth on micro-fibres. These data suggest that the topography of electrospun gelatin fibres can be adjusted to modulate SC and axon organization and that both nano- and micro-fibres are promising fillers for the design of devices for peripheral nerve repair. - Highlights: • Electrospinning used to produce gelatin nano- and micro-fibre matrices. • Nano-fibre matrices promote Schwann cell organization and increase proliferation rate. • Micro-fibre matrices promote Schwann cell migration. • Micro-fibre matrices promote axonal outgrowth

  3. The influence of electrospun fibre size on Schwann cell behaviour and axonal outgrowth

    Energy Technology Data Exchange (ETDEWEB)

    Gnavi, S., E-mail: sara.gnavi@unito.it [Department of Clinical and Biological Sciences, University of Torino, Orbassano 10043 (Italy); Neuroscience Institute of the Cavalieri-Ottolenghi Foundation, University of Torino, Orbassano 10043 (Italy); Fornasari, B.E., E-mail: benedettaelena.fornasari@unito.it [Department of Clinical and Biological Sciences, University of Torino, Orbassano 10043 (Italy); Neuroscience Institute of the Cavalieri-Ottolenghi Foundation, University of Torino, Orbassano 10043 (Italy); Tonda-Turo, C., E-mail: chiara.tondaturo@polito.it [Politecnico di Torino, Department of Mechanical and Aerospace Engineering, Politecnico of Torino, Torino 10100 (Italy); Ciardelli, G., E-mail: gianluca.ciardelli@polito.it [Politecnico di Torino, Department of Mechanical and Aerospace Engineering, Politecnico of Torino, Torino 10100 (Italy); CNR-IPCF UOS, Pisa 56124 (Italy); Zanetti, M., E-mail: marco.zanetti@unito.it [Nanostructured Interfaces and Surfaces, Department of Chemistry, University of Torino, Torino 10100 (Italy); Geuna, S., E-mail: stefano.geuna@unito.it [Department of Clinical and Biological Sciences, University of Torino, Orbassano 10043 (Italy); Neuroscience Institute of the Cavalieri-Ottolenghi Foundation, University of Torino, Orbassano 10043 (Italy); Perroteau, I., E-mail: isabelle.perroteau@unito.it [Department of Clinical and Biological Sciences, University of Torino, Orbassano 10043 (Italy)

    2015-03-01

    Fibrous substrates functioning as temporary extracellular matrices can be prepared easily by electrospinning, yielding fibrous matrices suitable as internal fillers for nerve guidance channels. In this study, gelatin micro- or nano-fibres were prepared by electrospinning by tuning the gelatin concentration and solution flow rate. The effect of gelatin fibre diameter on cell adhesion and proliferation was tested in vitro using explant cultures of Schwann cells (SC) and dorsal root ganglia (DRG). Cell adhesion was assessed by quantifying the cell spreading area, actin cytoskeleton organization and focal adhesion complex formation. Nano-fibres promoted cell spreading and actin cytoskeleton organization, increasing cellular adhesion and the proliferation rate. However, both migration rate and motility, quantified by transwell and time lapse assays respectively, were greater in cells cultured on micro-fibres. Finally, there was more DRG axon outgrowth on micro-fibres. These data suggest that the topography of electrospun gelatin fibres can be adjusted to modulate SC and axon organization and that both nano- and micro-fibres are promising fillers for the design of devices for peripheral nerve repair. - Highlights: • Electrospinning used to produce gelatin nano- and micro-fibre matrices. • Nano-fibre matrices promote Schwann cell organization and increase proliferation rate. • Micro-fibre matrices promote Schwann cell migration. • Micro-fibre matrices promote axonal outgrowth.

  4. Sizing stack and battery of a fuel cell hybrid distribution truck

    NARCIS (Netherlands)

    Bosch, P.P.J. van den; Hofman, T.; Veenhuizen, Bram; Shen, Y.; Tazelaar, Edwin

    2012-01-01

    Fuel cell hybrid vehicles are believed to provide a solution to cut down emissions in the long term. They provide local zero-emission propulsion and when the hydrogen as fuel is derived from renewable energy sources, fuel cell hybrids enable well-to-wheel zero-emission transportation,

  5. Synthesis and activation of Pt nanoparticles with controlled size for fuel cell electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhufang; Reichert, W. Matthew; Nikles, David E. [Department of Chemistry, The University of Alabama, Tuscaloosa, AL 35487-0336 (United States); Shamsuzzoha, Mohammad; Ada, Earl T. [Central Analytical Facility, The University of Alabama, Tuscaloosa, AL 35487-0336 (United States)

    2007-02-10

    Well-dispersed Pt nanoparticles with controlled size and narrow size distribution were prepared by polyalcohol reduction of platinum acetylacetonate, using oleylamine as a capping agent. The particle size was varied from 3.5 nm to 11.5 nm by decreasing the amount of oleylamine added in the synthesis. Size selection of the as-prepared particles by solvent fractionation yielded nearly monodispersed Pt particles. The as-prepared particles were loaded on a carbon support by physical deposition, but showed no electrocatalytic activity due to the oleylamine bound to the particle surface. The particles were activated for electrocatalysis after heating the particles in air at 185 C for 5 h, conditions that gave no particle-sintering and no oxidation. Cyclic voltammetry showed that the particles after the heat treatment in air were electrocatalytically active for methanol oxidation. The smaller 3.5 nm and 4.0 nm Pt particles had a higher intrinsic activity for methanol oxidation, but a lower tolerance to CO poisoning, compared with 6.0 nm, 9.5 nm and 11.5 nm particles. CO-stripping results suggest that CO is more easily oxidized on larger Pt particles. (author)

  6. Plasmonic nanoparticle films for solar cell applications fabricated by size-selective aerosol deposition

    NARCIS (Netherlands)

    Pfeiffer, T.V.; Ortiz Gonzalez, J.; Santbergen, R.; Tan, H.; Schmidt-Ott, A.; Zeman, M.; Smets, A.H.M.

    2014-01-01

    A soft deposition method for incorporating surface plasmon resonant metal nanoparticles within photovoltaic devices was studied. This self-assembly method provides excellent control over both nanoparticle size and surface coverage. Films of spherical Ag nanoparticles with diameter of ∼100 nm were fa

  7. Effects of Size-Fractionated Particulate Matter on Cellular Oxidant Radical Generation in Human Bronchial Epithelial BEAS-2B Cells.

    Science.gov (United States)

    Guan, Longfei; Rui, Wei; Bai, Ru; Zhang, Wei; Zhang, Fang; Ding, Wenjun

    2016-01-01

    The aim of the present study was to investigate the effects of size-fractionated (i.e., cell viability in human bronchial epithelial cells (BEAS-2B). The PM samples were collected from an urban site (uPM) in Beijing and a steel factory site (sPM) in Anshan, China, from March 2013 to December 2014. Metal elements, organic and elemental carbon, and water-soluble inorganic ions in the uPM and sPM were analyzed. The cell viability and ROS generation in PM-exposed BEAS-2B cells were measured by MTS and DCFH-DA. The results showed that both uPM and sPM caused a decrease in the cell viability and an increase in ROS generation. The level of ROS measured in sPM1.0 was approximately triple that in uPM1.0. The results of correlation analysis showed that the ROS activity and cytotoxicity were related to different PM composition. Moreover, deferoxamine (DFO) significantly prevented the increase of ROS generation and the decrease of cell viability. Taken together, our results suggest that the metals absorbed on PM induced oxidant radical generation in BEAS-2B cells that could lead to impairment of pulmonary function. PMID:27171105

  8. Effects of Size-Fractionated Particulate Matter on Cellular Oxidant Radical Generation in Human Bronchial Epithelial BEAS-2B Cells

    Directory of Open Access Journals (Sweden)

    Longfei Guan

    2016-05-01

    Full Text Available The aim of the present study was to investigate the effects of size-fractionated (i.e., <1; 1–2.5, and 2.5–10 µm in an aerodynamic diameter ambient particulate matter (PM on reactive oxygen species (ROS activity and cell viability in human bronchial epithelial cells (BEAS-2B. The PM samples were collected from an urban site (uPM in Beijing and a steel factory site (sPM in Anshan, China, from March 2013 to December 2014. Metal elements, organic and elemental carbon, and water-soluble inorganic ions in the uPM and sPM were analyzed. The cell viability and ROS generation in PM-exposed BEAS-2B cells were measured by MTS and DCFH-DA. The results showed that both uPM and sPM caused a decrease in the cell viability and an increase in ROS generation. The level of ROS measured in sPM1.0 was approximately triple that in uPM1.0. The results of correlation analysis showed that the ROS activity and cytotoxicity were related to different PM composition. Moreover, deferoxamine (DFO significantly prevented the increase of ROS generation and the decrease of cell viability. Taken together, our results suggest that the metals absorbed on PM induced oxidant radical generation in BEAS-2B cells that could lead to impairment of pulmonary function.

  9. Patterns in Abundance, Cell Size and Pigment Content of Aerobic Anoxygenic Phototrophic Bacteria along Environmental Gradients in Northern Lakes.

    Directory of Open Access Journals (Sweden)

    Lisa Fauteux

    Full Text Available There is now evidence that aerobic anoxygenic phototrophic (AAP bacteria are widespread across aquatic systems, yet the factors that determine their abundance and activity are still not well understood, particularly in freshwaters. Here we describe the patterns in AAP abundance, cell size and pigment content across wide environmental gradients in 43 temperate and boreal lakes of Québec. AAP bacterial abundance varied from 1.51 to 5.49 x 105 cells mL-1, representing <1 to 37% of total bacterial abundance. AAP bacteria were present year-round, including the ice-cover period, but their abundance relative to total bacterial abundance was significantly lower in winter than in summer (2.6% and 7.7%, respectively. AAP bacterial cells were on average two-fold larger than the average bacterial cell size, thus AAP cells made a greater relative contribution to biomass than to abundance. Bacteriochlorophyll a (BChla concentration varied widely across lakes, and was not related to AAP bacterial abundance, suggesting a large intrinsic variability in the cellular pigment content. Absolute and relative AAP bacterial abundance increased with dissolved organic carbon (DOC, whereas cell-specific BChla content was negatively related to chlorophyll a (Chla. As a result, both the contribution of AAP bacteria to total prokaryotic abundance, and the cell-specific BChla pigment content were positively correlated with the DOC:Chla ratio, both peaking in highly colored, low-chlorophyll lakes. Our results suggest that photoheterotrophy might represent a significant ecological advantage in highly colored, low-chlorophyll lakes, where DOC pool is chemically and structurally more complex.

  10. A novel microfluidic platform for size and deformability based separation and the subsequent molecular characterization of viable circulating tumor cells.

    Science.gov (United States)

    Hvichia, G E; Parveen, Z; Wagner, C; Janning, M; Quidde, J; Stein, A; Müller, V; Loges, S; Neves, R P L; Stoecklein, N H; Wikman, H; Riethdorf, S; Pantel, K; Gorges, T M

    2016-06-15

    Circulating tumor cells (CTCs) were introduced as biomarkers more than 10 years ago, but capture of viable CTCs at high purity from peripheral blood of cancer patients is still a major technical challenge. Here, we report a novel microfluidic platform designed for marker independent capture of CTCs. The Parsortix™ cell separation system provides size and deformability-based enrichment with automated staining for cell identification, and subsequent recovery (harvesting) of cells from the device. Using the Parsortix™ system, average cell capture inside the device ranged between 42% and 70%. Subsequent harvest of cells from the device ranged between 54% and 69% of cells captured. Most importantly, 99% of the isolated tumor cells were viable after processing in spiking experiments as well as after harvesting from patient samples and still functional for downstream molecular analysis as demonstrated by mRNA characterization and array-based comparative genomic hybridization. Analyzing clinical blood samples from metastatic (n = 20) and nonmetastatic (n = 6) cancer patients in parallel with CellSearch(®) system, we found that there was no statistically significant difference between the quantitative behavior of the two systems in this set of twenty six paired separations. In conclusion, the epitope independent Parsortix™ system enables the isolation of viable CTCs at a very high purity. Using this system, viable tumor cells are easily accessible and ready for molecular and functional analysis. The system's ability for enumeration and molecular characterization of EpCAM-negative CTCs will help to broaden research into the mechanisms of cancer as well as facilitating the use of CTCs as "liquid biopsies." PMID:26789903

  11. Effect of size of bioactive glass nanoparticles on mesenchymal stem cell proliferation for dental and orthopedic applications

    Energy Technology Data Exchange (ETDEWEB)

    Ajita, J.; Saravanan, S.; Selvamurugan, N., E-mail: selvamurugan.n@ktr.srmuniv.ac.in

    2015-08-01

    Bioactive glass nanoparticles (nanostructured bioglass ceramics or nBGs) have been widely employed as a filler material for bone tissue regeneration. The physical properties of nBG particles govern their biological actions. In this study, the impact of the size of nBG particles on mouse mesenchymal stem cell (mMSC) proliferation was investigated. Three different sizes of nBG particles were prepared via the sol–gel method with varying concentrations of the surfactant and polyethylene glycol (PEG), and the particles were characterized. Increased concentrations of PEG decreased the size of nBG particles (nBG-1: 74.7 ± 0.62 nm, nBG-2: 43.25 ± 1.5 nm, and nBG-3: 37.6 ± 0.81 nm). All three nBGs were non-toxic at a concentration of 20 mg/mL. Increased proliferation was observed in mMSCs treated with smaller nBG particles. Differential mRNA expression of cyclin A2, B2, D1, and E1 genes induced by nBG particles was noticed in the mMSCs. nBG-1 and nBG-3 particles promoted cells in the G0/G1 phase to enter the S and G2/M phases. nBG particles activated ERK, but prolonged activation was achieved with nBG-3 particles. Among the prepared nBG particles, nBG-3 particles showed enhanced mMSC proliferation via the sustained activation of ERKs, upregulation of cyclin gene(s) expression, and promotion of cell transition from the G0/G1 phase to the S and G2/M phases. Thus, this study indicates that small nBG particles have clinical applications in dental and bone treatments as fillers or bone-tissue bond forming materials. - Highlights: • Three different sizes of bioactive glass nanoparticles (nBGs) were prepared via the sol–gel method. • Increased concentrations of polyethylene glycol decreased the size of nBG particles. • All three nBGs were non-toxic at a concentration of 20 mg/mL. • Cell number, cell cycle phase analysis, cyclin gene expression and ERK activation were studied. • Increased proliferation was observed in mMSCs treated with smaller nBG particles.

  12. Effect of size of bioactive glass nanoparticles on mesenchymal stem cell proliferation for dental and orthopedic applications

    International Nuclear Information System (INIS)

    Bioactive glass nanoparticles (nanostructured bioglass ceramics or nBGs) have been widely employed as a filler material for bone tissue regeneration. The physical properties of nBG particles govern their biological actions. In this study, the impact of the size of nBG particles on mouse mesenchymal stem cell (mMSC) proliferation was investigated. Three different sizes of nBG particles were prepared via the sol–gel method with varying concentrations of the surfactant and polyethylene glycol (PEG), and the particles were characterized. Increased concentrations of PEG decreased the size of nBG particles (nBG-1: 74.7 ± 0.62 nm, nBG-2: 43.25 ± 1.5 nm, and nBG-3: 37.6 ± 0.81 nm). All three nBGs were non-toxic at a concentration of 20 mg/mL. Increased proliferation was observed in mMSCs treated with smaller nBG particles. Differential mRNA expression of cyclin A2, B2, D1, and E1 genes induced by nBG particles was noticed in the mMSCs. nBG-1 and nBG-3 particles promoted cells in the G0/G1 phase to enter the S and G2/M phases. nBG particles activated ERK, but prolonged activation was achieved with nBG-3 particles. Among the prepared nBG particles, nBG-3 particles showed enhanced mMSC proliferation via the sustained activation of ERKs, upregulation of cyclin gene(s) expression, and promotion of cell transition from the G0/G1 phase to the S and G2/M phases. Thus, this study indicates that small nBG particles have clinical applications in dental and bone treatments as fillers or bone-tissue bond forming materials. - Highlights: • Three different sizes of bioactive glass nanoparticles (nBGs) were prepared via the sol–gel method. • Increased concentrations of polyethylene glycol decreased the size of nBG particles. • All three nBGs were non-toxic at a concentration of 20 mg/mL. • Cell number, cell cycle phase analysis, cyclin gene expression and ERK activation were studied. • Increased proliferation was observed in mMSCs treated with smaller nBG particles

  13. Universal real-time PCR assay for quantitation and size evaluation of residual cell DNA in human viral vaccines.

    Science.gov (United States)

    André, Murielle; Reghin, Sylviane; Boussard, Estelle; Lempereur, Laurent; Maisonneuve, Stéphane

    2016-05-01

    Residual host cellular DNA (rcDNA) is one of the principal risk associated with continuous cell lines derived medicines such as viral vaccines. To assess rcDNA degradation, we suggest two quantitative real-time PCR assays designed to separately quantify target sequences shorter and longer than the 200 bp risk limit, the relative abundance of both targets reflecting the extent of rcDNA fragmentation. The conserved multicopy ribosomal 18S RNA gene was targeted to detect host cell templates from most mammalian cell substrates commonly used in the manufacture of human viral vaccines. The detection range of the method was assessed on purified DNA templates from different animal origins. The standard calibrator origin and structural conformation were shown crucial to achieve accurate quantification. Artificial mixtures of PCR products shorter and longer than 200 bp were used as a model to check the ability of the assay to estimate the fragment size distribution. The method was successfully applied to a panel of Vero cell derived vaccines and could be used as a universal method for determination of both content and size distribution of rcDNA in vaccines. PMID:27033773

  14. Optimization of temperature, sugar concentration, and inoculum size to maximize ethanol production without significant decrease in yeast cell viability

    Energy Technology Data Exchange (ETDEWEB)

    Laluce, Cecilia; Morais, Meline Rezende [Inst. de Quimica de Araraquara-UNESP, SP (Brazil). Dept. of Biochemistry and Biotechnological Chemistry; Tognolli, Joao Olimpio [Inst. de Quimica de Araraquara-UNESP, SP (Brazil). Dept. of Analytical Chemistry; Oliveira, Karen Fernanda de; Souza, Crisla Serra [Cidade Universitaria, Sao Paulo, SP (Brazil). Programa de Pos-Graduacao Interunidades em Biotecnologia

    2009-06-15

    Aiming to obtain rapid fermentations with high ethanol yields and a retention of high final viabilities (responses), a 2{sup 3} full-factorial central composite design combined with response surface methodology was employed using inoculum size, sucrose concentration, and temperature as independent variables. From this statistical treatment, two well-fitted regression equations having coefficients significant at the 5% level were obtained to predict the viability and ethanol production responses. Three-dimensional response surfaces showed that increasing temperatures had greater negative effects on viability than on ethanol production. Increasing sucrose concentrations improved both ethanol production and viability. The interactions between the inoculum size and the sucrose concentrations had no significant effect on viability. Thus, the lowering of the process temperature is recommended in order to minimize cell mortality and maintain high levels of ethanol production when the temperature is on the increase in the industrial reactor. Optimized conditions (200 g/l initial sucrose, 40 g/l of dry cell mass, 30 C) were experimentally confirmed and the optimal responses are 80.8{+-}2.0 g/l of maximal ethanol plus a viability retention of 99.0{+-}3.0% for a 4-h fermentation period. During consecutive fermentations with cell reuse, the yeast cell viability has to be kept at a high level in order to prevent the collapse of the process. (orig.)

  15. Size does matter: why polyploid tumor cells are critical drug targets in the war on cancer.

    Directory of Open Access Journals (Sweden)

    AngusHarding

    2014-05-01

    Full Text Available Tumor evolution presents a formidable obstacle that currently prevents the development of truly curative treatments for cancer. In this perspective, we advocate for the hypothesis that tumor cells with significantly elevated genomic content (polyploid tumor cells facilitate rapid tumor evolution and the acquisition of therapy resistance in multiple incurable cancers. We appeal to studies conducted in yeast, cancer models and cancer patients, which all converge on the hypothesis that polyploidy enables large phenotypic leaps, providing access to many different therapy-resistant phenotypes. We develop a flow-cytometry based method for quantifying the prevalence of polyploid tumor cells, and show the frequency of these cells in patient tumors may be higher than is generally appreciated. We then present recent studies identifying promising new therapeutic strategies that could be used to specifically target polyploid tumor cells in cancer patients. We argue that these therapeutic approaches should be incorporated into new treatment strategies aimed at blocking tumor evolution by killing the highly evolvable, therapy resistant polyploid cell subpopulations, thus helping to maintain patient tumors in a drug sensitive state.

  16. Quantitative modeling of viable cell density, cell size, intracellular conductivity, and membrane capacitance in batch and fed-batch CHO processes using dielectric spectroscopy.

    Science.gov (United States)

    Opel, Cary F; Li, Jincai; Amanullah, Ashraf

    2010-01-01

    Dielectric spectroscopy was used to analyze typical batch and fed-batch CHO cell culture processes. Three methods of analysis (linear modeling, Cole-Cole modeling, and partial least squares regression), were used to correlate the spectroscopic data with routine biomass measurements [viable packed cell volume, viable cell concentration (VCC), cell size, and oxygen uptake rate (OUR)]. All three models predicted offline biomass measurements accurately during the growth phase of the cultures. However, during the stationary and decline phases of the cultures, the models decreased in accuracy to varying degrees. Offline cell radius measurements were unsuccessfully used to correct for the deviations from the linear model, indicating that physiological changes affecting permittivity were occurring. The beta-dispersion was analyzed using the Cole-Cole distribution parameters Deltaepsilon (magnitude of the permittivity drop), f(c) (critical frequency), and alpha (Cole-Cole parameter). Furthermore, the dielectric parameters static internal conductivity (sigma(i)) and membrane capacitance per area (C(m)) were calculated for the cultures. Finally, the relationship between permittivity, OUR, and VCC was examined, demonstrating how the definition of viability is critical when analyzing biomass online. The results indicate that the common assumptions of constant size and dielectric properties used in dielectric analysis are not always valid during later phases of cell culture processes. The findings also demonstrate that dielectric spectroscopy, while not a substitute for VCC, is a complementary measurement of viable biomass, providing useful auxiliary information about the physiological state of a culture. PMID:20730773

  17. Biological responses according to the shape and size of carbon nanotubes in BEAS-2B and MESO-1 cells

    Directory of Open Access Journals (Sweden)

    Haniu H

    2014-04-01

    Full Text Available Hisao Haniu,1,2 Naoto Saito,2,3 Yoshikazu Matsuda,4 Tamotsu Tsukahara,5 Yuki Usui,1,6,7 Kayo Maruyama,2,3 Seiji Takanashi,1 Kaoru Aoki,1 Shinsuke Kobayashi,1 Hiroki Nomura,1 Manabu Tanaka,1 Masanori Okamoto,1 Hiroyuki Kato1 1Department of Orthopaedic Surgery, Shinshu University School of Medicine, Nagano, Japan; 2Insutitute for Biomedical Sciences, Shinshu University, Nagano, Japan; 3Department of Applied Physical Therapy, Shinshu University School of Health Sciences, Nagano, Japan; 4Clinical Pharmacology Educational Center, Nihon Pharmaceutical University, Saitama, Japan; 5Department of Hematology and Immunology, Kanazawa Medical University, Ishikawa, Japan; 6Research Center for Exotic Nanocarbons, Shinshu University, Nagano, Japan; 7Aizawa Hospital, Sports Medicine Center, Nagano, Japan Abstract: This study aimed to investigate the influence of the shape and size of multi-walled carbon nanotubes (MWCNTs and cup-stacked carbon nanotubes (CSCNTs on biological responses in vitro. Three types of MWCNTs – VGCF®-X, VGCF®-S, and VGCF® (vapor grown carbon fibers; with diameters of 15, 80, and 150 nm, respectively – and three CSCNTs of different lengths (CS-L, 20–80 µm; CS-S, 0.5–20 µm; and CS-M, of intermediate length were tested. Human bronchial epithelial (BEAS-2B and malignant pleural mesothelioma cells were exposed to the CNTs (1–50 µg/mL, and cell viability, permeability, uptake, total reactive oxygen species/superoxide production, and intracellular acidity were measured. CSCNTs were less toxic than MWCNTs in both cell types over a 24-hour exposure period. The cytotoxicity of endocytosed MWCNTs varied according to cell type/size, while that of CSCNTs depended on tube length irrespective of cell type. CNT diameter and length influenced cell aggregation and injury extent. Intracellular acidity increased independently of lysosomal activity along with the number of vacuoles in BEAS-2B cells exposed for 24 hours to either CNT

  18. Adipose Tissue Fatty Acid Storage Factors: Effects of Depot, Sex and Fat Cell Size

    OpenAIRE

    Hames, Kazanna C.; Koutsari, Christina; Santosa, Sylvia; Bush, Nikki C.; Jensen, Michael D.

    2015-01-01

    Background/Objectives Patterns of postabsorptive adipose tissue fatty acid storage correlate with sex-specific body fat distribution. Some proteins and enzymes participating in this pathway include CD36 (facilitated transport), acyl-CoA synthetases (ACS; the first step in fat metabolism), and diacylglycerol acetyl-transferase (DGAT; the final step of triglyceride synthesis). Our goal was to better define CD36, ACS and DGAT in relation to sex, subcutaneous fat depots, and adipocyte size. Subje...

  19. Efficient replication bypass of size-expanded DNA base pairs in bacterial cells

    OpenAIRE

    Delaney, James C.; GAO, JIANMIN; Liu, Haibo; Shrivastav, Nidhi; Essigmann, John M.; Kool, Eric T.

    2009-01-01

    Supersize me! Size-expanded DNA bases (xDNA) are able to encode natural DNA sequences in replication. In vitro experiments with a DNA polymerase show nucleotide incorporation opposite the xDNA bases with correct pairing. In vivo experiments using E. coli show that two xDNA bases (xA and xC, see picture) encode the correct replication partners.

  20. Recovery of ovary size, follicle cell apoptosis, and HSP70 expression in fish exposed to bleached pulp mill effluent

    Energy Technology Data Exchange (ETDEWEB)

    Janz, D. M.; Weber, L. P. [Oklahoma State Univ., Stillwater, OK (United States); McMaster, M. E.; Munkittrrick, K. R. [Environment Canada, Burlington, ON (Canada); Van Der Kraak, G. [Guelph Univ., Dept. of Zoology, ON (Canada)

    2001-03-01

    Apoptosis of granulosa cells that provide hormonal support for the oocyte is the normal mechanism by which atresia ( reduced ovarian size, decreased fecundity, delayed sexual maturation, alterations in plasma sex steroid levels, etc) occurs in mammals, birds and possibly fish. The objective of this study is to determine ovarian cell apoptosis, gonadosomatic index (GSI) and heat shock protein (HSP70) expression during the growth stage of ovarian development in white sucker fish in order to compare samples of fish collected upstream and downstream of a bleached kraft pulp mill in Ontario. Fish for the study were collected in two different years, before and after the pulp mill undertook a number of improvements to eliminate the release of process chemicals. Results showed a 3.4-fold increase in ovarian cell apoptosis in growing white sucker collected four km downstream of the bleached kraft pulp mill in 1996 (before the improvements) compared to fish collected from upstream sources. The elevated ovarian cell apoptosis was associated with significant reduction in gonadosomatic index in fish collected downstream. There were no differences in ovarian cell apoptosis or gonadosomatic index between fish collected upstream and four km downstream of the mill in September 1998 (after the improvements.) Based on the results, it may be concluded that chronic stimulation of ovarian cell apoptosis by certain components of bleached kraft pulp mill effluents represents an important cellular mechanism for reducing the size of ovaries and other related reproductive responses in female fish exposed to these effluents. Although the specific effluent components are not known, the improvements undertaken between 1996 and 1998 resulted in significant enough recovery of these responses to justify the belief in a cause-effect relationship. 32 refs., 1 tab., 2 figs.

  1. Histomorphology of the bottlenose dolphin (Tursiops truncatus) pancreas and association of increasing islet β-cell size with chronic hypercholesterolemia.

    Science.gov (United States)

    Colegrove, Kathleen M; Venn-Watson, Stephanie

    2015-04-01

    Bottlenose dolphins (Tursiops truncatus) can develop metabolic states mimicking prediabetes, including hyperinsulinemia, hyperlipidemia, elevated glucose, and fatty liver disease. Little is known, however, about dolphin pancreatic histomorphology. Distribution and area of islets, α, β, and δ cells were evaluated in pancreatic tissue from 22 dolphins (mean age 25.7years, range 0-51). Associations of these measurements were evaluated by sex, age, percent high glucose and lipids during the last year of life, and presence or absence of fatty liver disease and islet cell vacuolation. The most common pancreatic lesions identified were exocrine pancreas fibrosis (63.6%) and mild islet cell vacuolation (47.4%); there was no evidence of insulitis or amyloid deposition, changes commonly associated with type 2 diabetes. Dolphin islet architecture appears to be most similar to the pig, where α and β cells are localized to the central or periphery of the islet, respectively, or are well dispersed throughout the islet. Unlike pigs, large islets (greater than 10,000μm(2)) were common in dolphins, similar to that found in humans. A positive linear association was identified between dolphin age and islet area average, supporting a compensatory response similar to other species. The strongest finding in this study was a positive linear association between islet size, specifically β-cells, and percent blood samples with high cholesterol (greater than 280mg/dl, R(2)=0.57). This study is the most comprehensive assessment of the dolphin pancreas to date and may help direct future studies, including associations between chronic hypercholesterolemia and β-cell size. PMID:25745813

  2. Attachment and invasion of Neisseria meningitidis to host cells is related to surface hydrophobicity, bacterial cell size and capsule.

    Directory of Open Access Journals (Sweden)

    Stephanie N Bartley

    Full Text Available We compared exemplar strains from two hypervirulent clonal complexes, strain NMB-CDC from ST-8/11 cc and strain MC58 from ST-32/269 cc, in host cell attachment and invasion. Strain NMB-CDC attached to and invaded host cells at a significantly greater frequency than strain MC58. Type IV pili retained the primary role for initial attachment to host cells for both isolates regardless of pilin class and glycosylation pattern. In strain MC58, the serogroup B capsule was the major inhibitory determinant affecting both bacterial attachment to and invasion of host cells. Removal of terminal sialylation of lipooligosaccharide (LOS in the presence of capsule did not influence rates of attachment or invasion for strain MC58. However, removal of either serogroup B capsule or LOS sialylation in strain NMB-CDC increased bacterial attachment to host cells to the same extent. Although the level of inhibition of attachment by capsule was different between these strains, the regulation of the capsule synthesis locus by the two-component response regulator MisR, and the level of surface capsule determined by flow cytometry were not significantly different. However, the diplococci of strain NMB-CDC were shown to have a 1.89-fold greater surface area than strain MC58 by flow cytometry. It was proposed that the increase in surface area without changing the amount of anchored glycolipid capsule in the outer membrane would result in a sparser capsule and increase surface hydrophobicity. Strain NMB-CDC was shown to be more hydrophobic than strain MC58 using hydrophobicity interaction chromatography and microbial adhesion-to-solvents assays. In conclusion, improved levels of adherence of strain NMB-CDC to cell lines was associated with increased bacterial cell surface and surface hydrophobicity. This study shows that there is diversity in bacterial cell surface area and surface hydrophobicity within N. meningitidis which influence steps in meningococcal pathogenesis.

  3. Passive electrophysiological properties of aged and axotomized cat spinal cord motoneurons: the effect of cell size and electrode shunt.

    Science.gov (United States)

    Engelhardt, J K; Chase, M H

    1992-07-01

    Intracellular recordings were obtained from intact and axotomized lumbar motoneurons of aged cats. The sub-threshold electrical properties of these cells were measured, including input resistance, resting membrane potential, and the first two equalizing time constants as well as their associated amplitude constants. These data were used in a semi-infinite cable model of the motoneuron to estimate the size of the shunt resistance (Rshunt) which is created when the electrode penetrates the cell membrane. The average Rshunt for intact aged cells was 5.35 +/- 1.01 M omega, while that for the axotomized aged cells was 8.93 +/- 1.20 M omega. The statistically significant difference in mean shunt magnitude did not affect the measurements of membrane time constant because this constant is independent of the shunt in this model of the motoneuron. However, the determination of cell input resistance, which is not independent of the shunt, was shown to underestimate the real cell input resistance by 23-29%. We therefore conclude that the shunt resistance is an important factor which should be taken into account when measuring input resistance. PMID:1508398

  4. A cell-targeted, size-photocontrollable, nuclear-uptake nanodrug delivery system for drug-resistant cancer therapy.

    Science.gov (United States)

    Qiu, Liping; Chen, Tao; Öçsoy, Ismail; Yasun, Emir; Wu, Cuichen; Zhu, Guizhi; You, Mingxu; Han, Da; Jiang, Jianhui; Yu, Ruqin; Tan, Weihong

    2015-01-14

    The development of multidrug resistance (MDR) has become an increasingly serious problem in cancer therapy. The cell-membrane overexpression of P-glycoprotein (P-gp), which can actively efflux various anticancer drugs from the cell, is a major mechanism of MDR. Nuclear-uptake nanodrug delivery systems, which enable intranuclear release of anticancer drugs, are expected to address this challenge by bypassing P-gp. However, before entering the nucleus, the nanocarrier must pass through the cell membrane, necessitating coordination between intracellular and intranuclear delivery. To accommodate this requirement, we have used DNA self-assembly to develop a nuclear-uptake nanodrug system carried by a cell-targeted near-infrared (NIR)-responsive nanotruck for drug-resistant cancer therapy. Via DNA hybridization, small drug-loaded gold nanoparticles (termed nanodrugs) can self-assemble onto the side face of a silver-gold nanorod (NR, termed nanotruck) whose end faces were modified with a cell type-specific internalizing aptamer. By using this size-photocontrollable nanodrug delivery system, anticancer drugs can be efficiently accumulated in the nuclei to effectively kill the cancer cells. PMID:25479133

  5. Genetic deletion of Rab27B in pancreatic acinar cells affects granules size and has inhibitory effects on amylase secretion.

    Science.gov (United States)

    Hou, Yanan; Ernst, Stephen A; Lentz, Stephen I; Williams, John A

    2016-03-18

    Small G protein Rab27B is expressed in various secretory cell types and plays a role in mediating secretion. In pancreatic acinar cells, Rab27B was found to be expressed on the zymogen granule membrane and by overexpression to regulate the secretion of zymogen granules. However, the effect of Rab27B deletion on the physiology of pancreatic acinar cells is unknown. In the current study, we utilized the Rab27B KO mouse model to better understand the role of Rab27B in the secretion of pancreatic acinar cells. Our data show that Rab27B deficiency had no obvious effects on the expression of major digestive enzymes and other closely related proteins, e.g. similar small G proteins, such as Rab3D and Rab27A, and putative downstream effectors. The overall morphology of acinar cells was not changed in the knockout pancreas. However, the size of zymogen granules was decreased in KO acinar cells, suggesting a role of Rab27B in regulating the maturation of secretory granules. The secretion of digestive enzymes was moderately decreased in KO acini, compared with the WT control. These data indicate that Rab27B is involved at a different steps of zymogen granule maturation and secretion, which is distinct from that of Rab3D. PMID:26845357

  6. Volumetric MR-HIFU ablation of uterine fibroids: Role of treatment cell size in the improvement of energy efficiency

    International Nuclear Information System (INIS)

    Purpose: To evaluate the energy efficiency of differently sized volumetric ablations in MR-guided high-intensity focused ultrasound (MR-HIFU) treatment of uterine fibroids. Materials and methods: This study was approved by the institutional review board and informed consent was obtained from all participants. Ten symptomatic uterine fibroids (mean diameter 8.9 cm) in 10 women (mean age 42.2) were treated by volumetric MR-HIFU ablation under binary feedback control. The energy efficiency (mm3/J) of each sonication was calculated as the volume of lethal thermal dose (240 equivalent minutes at 43 °C) per unit acoustic energy applied. Operator-controllable parameters and signal intensity ratio of uterine fibroid to skeletal muscle on T2-weighted MR images were tested with univariate and multivariate analyses to discern which parameters significantly correlated with the ablation energy efficiency. Results: We analyzed a total of 236 sonications. The energy efficiency of the ablations was 0.42 ± 0.25 mm3/J (range 0.004–1.18) with energy efficiency improving with the treatment cell size (4 mm, 0.06 ± 0.06 mm3/J; 8 mm, 0.29 ± 0.12 mm3/J; 12 mm, 0.58 ± 0.18 mm3/J; 16 mm, 0.91 ± 0.17 mm3/J). Treatment cell size (r = 0.814, p < 0.001), distance of ultrasound propagation (r = −0.151, p = 0.020), sonication frequency (1.2 or 1.45 MHz; p < 0.001), and signal intensity ratio (r = −0.205, p = 0.002) proved to be significant by univariate analysis, while multivariate analysis revealed treatment cell size (B = 0.075, p < 0.001), US propagation distance (B = −6.928, p < 0.001), and signal intensity ratio (B = −0.024, p = 0.001) to be independently significant. Conclusion: Energy efficiency in volumetric MR-HIFU ablation of uterine fibroids improves with increased treatment cell size, independent of other significant contributors such as distance of ultrasound propagation or signal intensity of the tumor on T2-weighted MR imaging.

  7. Volumetric MR-HIFU ablation of uterine fibroids: Role of treatment cell size in the improvement of energy efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young-sun [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Keserci, Bilgin [Philips Healthcare, Seoul (Korea, Republic of); Partanen, Ari [Philips Healthcare, Cleveland, OH (United States); Rhim, Hyunchul, E-mail: rhimhc@skku.edu [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Lim, Hyo K.; Park, Min Jung [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Koehler, Max O. [Philips Healthcare, Vantaa (Finland)

    2012-11-15

    Purpose: To evaluate the energy efficiency of differently sized volumetric ablations in MR-guided high-intensity focused ultrasound (MR-HIFU) treatment of uterine fibroids. Materials and methods: This study was approved by the institutional review board and informed consent was obtained from all participants. Ten symptomatic uterine fibroids (mean diameter 8.9 cm) in 10 women (mean age 42.2) were treated by volumetric MR-HIFU ablation under binary feedback control. The energy efficiency (mm{sup 3}/J) of each sonication was calculated as the volume of lethal thermal dose (240 equivalent minutes at 43 Degree-Sign C) per unit acoustic energy applied. Operator-controllable parameters and signal intensity ratio of uterine fibroid to skeletal muscle on T2-weighted MR images were tested with univariate and multivariate analyses to discern which parameters significantly correlated with the ablation energy efficiency. Results: We analyzed a total of 236 sonications. The energy efficiency of the ablations was 0.42 {+-} 0.25 mm{sup 3}/J (range 0.004-1.18) with energy efficiency improving with the treatment cell size (4 mm, 0.06 {+-} 0.06 mm{sup 3}/J; 8 mm, 0.29 {+-} 0.12 mm{sup 3}/J; 12 mm, 0.58 {+-} 0.18 mm{sup 3}/J; 16 mm, 0.91 {+-} 0.17 mm{sup 3}/J). Treatment cell size (r = 0.814, p < 0.001), distance of ultrasound propagation (r = -0.151, p = 0.020), sonication frequency (1.2 or 1.45 MHz; p < 0.001), and signal intensity ratio (r = -0.205, p = 0.002) proved to be significant by univariate analysis, while multivariate analysis revealed treatment cell size (B = 0.075, p < 0.001), US propagation distance (B = -6.928, p < 0.001), and signal intensity ratio (B = -0.024, p = 0.001) to be independently significant. Conclusion: Energy efficiency in volumetric MR-HIFU ablation of uterine fibroids improves with increased treatment cell size, independent of other significant contributors such as distance of ultrasound propagation or signal intensity of the tumor on T2-weighted MR

  8. Preparation of nanoparticle size LiBiO2 by combustion method and its electrochemical studies for lithium secondary cells

    Indian Academy of Sciences (India)

    R Sathyamoorthi; A Subramania; R Gangadharan; T Vasudevan

    2005-11-01

    A simple combustion method has been tried for the preparation of nanoparticle-sized LiBiO2 powder with urea as the igniter and glycerol as the binding material. Nitrates of Li+ and Bi3+ were mixed together to form a uniform mixture. Required quantities of urea and glycerol were added to this mixture to form a paste. This paste was carefully heated to 100°C initially and finally heated to 460°C for 5 h. The product obtained was subjected to TG/DTA and XRD analysis. The particle size of the cathode material was roughly calculated from the X-ray data using Scherer equation. However, SEM and EDAX analysis were carried out in detail to confirm the particle size and the composition of LiBiO2 respectively. A 2016 coin type button cell was assembled with LiBiO2 as cathode and graphite as anode containing polypropylene separator and a solution of 1 M LiClO4 dissolved in 1:1 (EC+DEC) mixture as the electrolyte. Charge/discharge studies were conducted to establish viability of the reversible cell.

  9. "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

    Science.gov (United States)

    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.

  10. Nano-sized LiCoO_2 Cathode for Use in Lithium-ion Cells

    Institute of Scientific and Technical Information of China (English)

    J.Yamaki; T.Doi; S.Okada

    2007-01-01

    1 Results Lithium ion batteries are widely used in many portable devices.However,their power density is not sufficient for use in electric vehicles.One of the most effective methods to improve the power density is the use of very fine cathode particles.We investigated new method,excess lithium method,of preparing nano-sized LiCoO2 powders.To begin with,lithium acetate and cobalt acetate are mixed by the molar ratio 9,13 or 21 to 1,uniformly.And the mixture is calcined at 600 ℃ for 6 hours.Finally,obtain...

  11. Size exclusion chromatography: an improved method to harvest Corynebacterium glutamicum cells for the analysis of cytosolic metabolites.

    Science.gov (United States)

    Persicke, Marcus; Plassmeier, Jens; Neuweger, Heiko; Rückert, Christian; Pühler, Alfred; Kalinowski, Jörn

    2011-07-10

    The efficient separation of Corynebacterium glutamicum cells from culture medium by size exclusion chromatography (SEC) is presented. Residue analysis demonstrated that this method effectively depletes extracellular compounds. For evaluation, SEC was compared with the common methods cold methanol treatment, fast centrifugation and fast filtration. For this purpose, samples of C. glutamicum cells from fermenter cultures were harvested and subjected to a metabolome analysis. In particular, the wild type strain C. glutamicum ATCC13032 and the lysine production strain C. glutamicum DM1730 were grown in a minimal or in a complex medium. Comparison of metabolite pool sizes after harvesting C. glutamicum cells by the methods mentioned above by gas chromatography coupled to mass spectrometry (GC-MS) revealed that SEC is the most suitable method when intracellular metabolite pools are to be measured during growth in complex media or in the presence of significant amounts of secreted metabolites. In contrast to the other methods tested, the SEC method turned out to be fast and able to remove extracellular compounds almost completely. PMID:20817050

  12. Evaluation of growth, cell size and biomass of Isochrysis aff. galbana (T-ISO with two LED regimes

    Directory of Open Access Journals (Sweden)

    Miguel Victor Cordoba-Matson

    2013-04-01

    Full Text Available In contrast to crops, there are fewer studies using LED-based light with green microalgae and none cultivating the microalga Isochrysis aff. galbana (T-ISO even though of its importance in marine aquaculture. The objective was to evaluate of white and red LEDs as an alternative source of light to cultivate I. aff. galbana (T-ISO. In order to carry this out white and red LEDs were used with a laboratory built Erlenmeyer-type photobioreactor to determine productivity, cell number and size and biomass composition. Results were compared with standard fluorescent lights of the same light intensity. The culture system consisted of 3 flasks for applying red LEDs and three for white LEDs and 3 control group flasks illuminated with the normal fluorescent lighting at the similar light intensity of ~60 mM m–2 s–1. It was found that the population cell density did not significantly increase with either red LEDs or white LEDs (p > 0.05, if at all. Standard fluorescent lighting (control group showed significant increases in population cell number (p < 0.05. Through microscopic observation cell size was found to be smaller for white LEDS and even smaller for red LEDs compared to fluorescent lighting. Biochemical composition of proteins, carbohydrates and lipids was similar for all light regimes. The authors suggest that the unexpected non-growth I. aff. galbana (T-ISO, a haptophyte microalga, with white and red LEDs is possibly due to fact that to initiate cell growth this microalgae requires other wavelengths (possibly green besides red and blue, to allow other pigments, probably fucoxanthin, to capture light

  13. Monitoring the size and lateral dynamics of ErbB1 enriched membrane domains through live cell plasmon coupling microscopy.

    Science.gov (United States)

    Rong, Guoxin; Reinhard, Björn M

    2012-01-01

    To illuminate the role of the spatial organization of the epidermal growth factor receptor (ErbB1) in signal transduction quantitative information about the receptor topography on the cell surface, ideally on living cells and in real time, are required. We demonstrate that plasmon coupling microscopy (PCM) enables to detect, size, and track individual membrane domains enriched in ErbB1 with high temporal resolution. We used a dendrimer enhanced labeling strategy to label ErbB1 receptors on epidermoid carcinoma cells (A431) with 60 nm Au nanoparticle (NP) immunolabels under physiological conditions at 37°C. The statistical analysis of the spatial NP distribution on the cell surface in the scanning electron microscope (SEM) confirmed a clustering of the NP labels consistent with a heterogeneous distribution of ErbB1 in the plasma membrane. Spectral shifts in the scattering response of clustered NPs facilitated the detection and sizing of individual NP clusters on living cells in solution in an optical microscope. We tracked the lateral diffusion of individual clusters at a frame rate of 200 frames/s while simultaneously monitoring the configurational dynamics of the clusters. Structural information about the NP clusters in their membrane confinements were obtained through analysis of the electromagnetic coupling of the co-confined NP labels through polarization resolved PCM. Our studies show that the ErbB1 receptor is enriched in membrane domains with typical diameters in the range between 60-250 nm. These membrane domains exhibit a slow lateral diffusion with a diffusion coefficient of D = |0.0054±0.0064| µm(2)/s, which is almost an order of magnitude slower than the mean diffusion coefficient of individual NP tagged ErbB1 receptors under identical conditions. PMID:22470534

  14. Fission yeast Nod1 is a component of cortical nodes involved in cell size control and division site placement.

    Directory of Open Access Journals (Sweden)

    Isabelle Jourdain

    Full Text Available Most cells enter mitosis once they have reached a defined size. In the fission yeast Schizosaccharomyces pombe, mitotic entry is orchestrated by a geometry-sensing mechanism that involves the Cdk1/Cdc2-inhibiting Wee1 kinase. The factors upstream of Wee1 gather together in interphase to form a characteristic medial and cortical belt of nodes. Nodes are also considered to be precursors of the cytokinesis contractile actomyosin ring (CAR. Here we describe a new component of the interphase nodes and cytokinesis rings, which we named Nod1. Consistent with its role in cell size control at division, nod1Δ cells were elongated and epistatic with regulators of Wee1. Through biochemical and localisation studies, we placed Nod1 in a complex with the Rho-guanine nucleotide exchange factor Gef2. Nod1 and Gef2 mutually recruited each other in nodes and Nod1 also assembles Gef2 in rings. Like gef2Δ, nod1Δ cells showed a mild displacement of their division plane and this phenotype was severely exacerbated when the parallel Polo kinase pathway was also compromised. We conclude that Nod1 specifies the division site by localising Gef2 to the mitotic cell middle. Previous work showed that Gef2 in turn anchors factors that control the spatio-temporal recruitment of the actin nucleation machinery. It is believed that the actin filaments originated from the nodes pull nodes together into a single contractile ring. Surprisingly however, we found that node proteins could form pre-ring helical filaments in a cdc12-112 mutant in which nucleation of the actin ring is impaired. Furthermore, the deletion of either nod1 or gef2 created an un-expected situation where different ring components were recruited sequentially rather than simultaneously. At later stages of cytokinesis, these various rings appeared inter-fitted rather than merged. This study brings a new slant to the understanding of CAR assembly and function.

  15. Size distribution of fullerenol nanoparticles in cell culture medium and their influence on antioxidative enzymes in Chinese hamster ovary cells

    Directory of Open Access Journals (Sweden)

    Srđenović Branislava U.

    2015-01-01

    Full Text Available Fullerenol (C60(OH24 nanoparticles (FNP have a significant role in biomedical research due to their numerous biological activities, some of which are cytoprotective and antioxidative properties. The aim of this study was to measure distribution of fullerenol nanoparticles and zeta potential in cell medium RPMI 1640 with 10% fetal bovine serum (FBS and to investigate the influence of FNP on Chinese hamster ovary cells (CHO-K1 survival, as well as to determine the activity of three antioxidative enzymes: superoxide-dismutase, glutathione-reductase and glutathione-S-transferase in mitomycin C-treated cell line. Our investigation implies that FNP, as a strong antioxidant, influence the cellular redox state and enzyme activities and thus may reduce cell proliferation, which confirms that FNP could be exploited for its use as a cytoprotective agent.[Projekat Ministarstva nauke Republike Srbije, br. III45005 i Pokrajinski Sekretarijat za nauku i tehnološki razvoj Vojvodine, grant number 114-451-2056/2011-01

  16. Preadipocyte transplantation: an in vivo study of direct leptin signaling on adipocyte morphogenesis and cell size

    OpenAIRE

    Guo, Kaiying; Mogen, Jonathan; Struzzi, Samuel; Zhang, Yiying

    2009-01-01

    Leptin has profound effects on adipose tissue metabolism. However, it remains unclear whether direct leptin signaling in adipocytes is involved. We addressed this question by transplanting inguinal adipose tissue stromal vascular cells (SVCs) from 4- to 5-wk-old wild-type (WT) and leptin receptor-deficient [Leprdb/db (db)] mice to inguinal and sternal subcutaneous sites in Ncr nude mice. Both WT and db SVCs gave rise to mature adipocytes with normal morphologies 3 mo after the transplantation...

  17. Conditioned Medium From Human Amniotic Mesenchymal Stromal Cells Limits Infarct Size and Enhances Angiogenesis

    OpenAIRE

    Danieli, Patrizia; Malpasso, Giuseppe; Ciuffreda, Maria Chiara; Cervio, Elisabetta; Calvillo, Laura; Copes, Francesco; Pisano, Federica; Mura, Manuela; Kleijn, Lennaert; De Boer, Rudolf A.; Viarengo, Gianluca; Rosti, Vittorio; Spinillo, Arsenio; Roccio, Marianna; Gnecchi, Massimiliano

    2015-01-01

    The goal of this study was to elucidate whether human amniotic membrane-derived mesenchymal stromal cells (hAMCs) can exert beneficial paracrine effects on infarcted rat hearts. In particular, the administration of hAMC-conditioned medium repaired ischemic damage through cardioprotection and angiogenesis. Finally, several putative active paracrine mediators that might account for the effects observed were identified by gene and protein arrays.

  18. MODELING, SIMULATON AND SIZING OF PHOTOVOLTAIC/WIND/FUEL CELL HYBRID GENERATION SYSTEM

    OpenAIRE

    Dr.S.LATHA; M.MAHALAKSHMI

    2012-01-01

    The depleting fossil fuel reserves and increasing concern towards global warming have created the need to surge for the alternative power generation options. Renewable energy sources like Wind, Solar-PV, Biomass and fuel cells are gaining prominence nowadays, as they are more energy efficient, reduce pollution and also they serveas a promising solution to the toughest energy crisis faced during the recent years. This paper focuses on the modeling and simulation of solar – photovoltaic, wind a...

  19. Insulin Resistance in Human iPS Cells Reduces Mitochondrial Size and Function

    OpenAIRE

    Burkart, Alison M.; Tan, Kelly; Warren, Laura; Iovino, Salvatore; Hughes, Katelyn J.; Kahn, C. Ronald; Patti, Mary-Elizabeth

    2016-01-01

    Insulin resistance, a critical component of type 2 diabetes (T2D), precedes and predicts T2D onset. T2D is also associated with mitochondrial dysfunction. To define the cause-effect relationship between insulin resistance and mitochondrial dysfunction, we compared mitochondrial metabolism in induced pluripotent stem cells (iPSC) from 5 healthy individuals and 4 patients with genetic insulin resistance due to insulin receptor mutations. Insulin-resistant iPSC had increased mitochondrial number...

  20. Chloride regulates leaf cell size and water relations in tobacco plants

    OpenAIRE

    Franco-Navarro, Juan D.; Brumós Fuentes, Javier; Rosales Villegas, Miguel Á.; Cubero Font, Paloma; Talón Cubillo, Manuel; Colmenero Flores, José M.

    2015-01-01

    Chloride (Cl–) is a micronutrient that accumulates to macronutrient levels since it is normally available in nature and actively taken up by higher plants. Besides a role as an unspecific cell osmoticum, no clear biological roles have been explicitly associated with Cl– when accumulated to macronutrient concentrations. To address this question, the glycophyte tobacco (Nicotiana tabacum L. var. Habana) has been treated with a basal nutrient solution supplemented with one of three salt combinat...

  1. RANKL and OPG activity is regulated by injury size in networks of osteocyte-like cells

    OpenAIRE

    Taylor, David

    2011-01-01

    PUBLISHED Bone remodelling is an intricate process encompassing numerous paracrine and autocrine biochemical pathways and mechanical mechanisms. It is responsible for maintaining bone homeostasis, structural integrity and function. The RANKL-RANK-OPG cytokine system is one of the principal mediators in the maintenance of bone cell function and activation of bone remodelling by the Basic Multicellular Unit (BMU) which carries out remodelling. Theories surrounding the initiation of bone remo...

  2. Serum ferritin in renal cell carcinoma: Effect of tumor size, volume grade, and stage

    OpenAIRE

    Singh Kamal; Singh S; Suri Amit; Vijjan Vivek; Goswami A; Khullar Madhu

    2005-01-01

    Aim: To study the levels of serum ferritin in patients of renal cell carcinoma (RCC). Patients and methods: Serum ferritin levels were measured preoperatively in 32 patients with radiological evidence of RCC using an enzyme immunoassay. The largest diameter of the primary tumor was measured in the pathological specimens in patients undergoing radical nephrectomy while in patients with nonoperable tumor maximum tumor dimension was taken from CT scan. Pathological staging was done according...

  3. Estimation of the target stem-cell population size in chronic myeloid leukemogenesis

    International Nuclear Information System (INIS)

    Estimation of the number of hematopoietic stem cells capable of causing chronic myeloid leukemia (CML) is relevant to the development of biologically based risk models of radiation-induced CML. Through a comparison of the age structure of CML incidence data from the Surveillance, Epidemiology, and End Results (SEER) Program and the age structure of chromosomal translocations found in healthy subjects, the number of CML target stem cells is estimated for individuals above 20 years of age. The estimation involves three steps. First, CML incidence among adults is fit to an exponentially increasing function of age. Next, assuming a relatively short waiting time distribution between BCR-ABL induction and the appearance of CML, an exponential age function with rate constants fixed to the values found for CML is fitted to the translocation data. Finally, assuming that translocations are equally likely to occur between any two points in the genome, the parameter estimates found in the first two steps are used to estimate the number of target stem cells for CML. The population-averaged estimates of this number are found to be 1.86 x 108 for men and 1.21 x 108 for women; the 95% confidence intervals of these estimates are (1.34 x 108, 2.50 x 108) and (0.84 x 108, 1.83 x 108), respectively. (orig.)

  4. Interrelated influence of iron, light and cell size on marine phytoplankton growth

    Science.gov (United States)

    Sunda, William G.; Huntsman, Susan A.

    1997-11-01

    The sub-optimal growth of phytoplankton and the resulting persistence of unutilized plant nutrients (nitrate and phosphate) in the surface waters of certain ocean regions has been a long-standing puzzle,. Of these regions, the Southern Ocean seems to play the greatest role in the global carbon cycle,, but controversy exists as to the dominant controls on net algal production. Limitation by iron deficiency,, light availability,, and grazing by zooplankton have been proposed. Here we present the results from culture experiments showing that the amount of cellular iron needed to support growth is higher under lower light intensities, owing to a greater requirement for photosynthetic iron-based redox proteins by low-light acclimatized algae. Moreover, algal iron uptake varies with cell surface area, such that the growth of small cells is favoured under iron limitation, as predicted theoretically. Phytoplankton growth can therefore be simultaneously limited by the availability of both iron and light. Such a co-limitation may be experienced by phytoplankton in iron-poor regions in which the surface mixed layer extends below the euphotic zone-as often occurs in the Southern Ocean,-or near the bottom of the euphotic zone in more stratified waters. By favouring the growth of smaller cells, iron/light co-limitation should increase grazing by microzooplankton, and thus minimize the loss of fixed carbon and nitrogen from surface waters in settling particles,.

  5. Size-dependent effects of tungsten carbide-cobalt particles on oxygen radical production and activation of cell signaling pathways in murine epidermal cells

    International Nuclear Information System (INIS)

    Hard metal or cemented carbide consists of a mixture of tungsten carbide (WC) (85%) and metallic cobalt (Co) (5-15%). WC-Co is considered to be potentially carcinogenic to humans. However, no comparison of the adverse effects of nano-sized WC-Co particles is available to date. In the present study, we compared the ability of nano- and fine-sized WC-Co particles to form free radicals and propensity to activate the transcription factors, AP-1 and NF-κB, along with stimulation of mitogen-activated protein kinase (MAPK) signaling pathways in a mouse epidermal cell line (JB6 P+). Our results demonstrated that nano-WC-Co generated a higher level of hydroxyl radicals, induced greater oxidative stress, as evidenced by a decrease of GSH levels, and caused faster JB6 P+ cell growth/proliferation than observed after exposure of cells to fine WC-Co. In addition, nano-WC-Co activated AP-1 and NF-κB more efficiently in JB6+/+ cells as compared to fine WC-Co. Experiments using AP-1-luciferase reporter transgenic mice confirmed the activation of AP-1 by nano-WC-Co. Nano- and fine-sized WC-Co particles also stimulated MAPKs, including ERKs, p38, and JNKs with significantly higher potency of nano-WC-Co. Finally, co-incubation of the JB6+/+ cells with N-acetyl-cysteine decreased AP-1 activation and phosphorylation of ERKs, p38 kinase, and JNKs, thus suggesting that oxidative stress is involved in WC-Co-induced toxicity and AP-1 activation.

  6. Fabrication and Characterization of a Perovskite-Type Solar Cell with a Substrate Size of 70 mm

    OpenAIRE

    Takeo Oku; Taisuke Matsumoto; Atsushi Suzuki; Kohei Suzuki

    2015-01-01

    A perovskite-type solar cell with a substrate size of 70 mm × 70 mm was fabricated by a simple spin-coating method using a mixed solution. The photovoltaic properties of the TiO2/CH3NH3PbI3-based photovoltaic devices were investigated by current density-voltage characteristic and incident photon to current conversion efficiency measurements. Their short-circuit current densities were almost constant over a large area. The photoconversion efficiency was influenced by the open-circuit voltage, ...

  7. Phospholipase D regulates the size of skeletal muscle cells through the activation of mTOR signaling.

    OpenAIRE

    Jaafar, Rami; De Larichaudy, Joffrey; Chanon, Stéphanie; Euthine, Vanessa; Durand, Christine; Naro, Fabio; Bertolino, Philippe; Vidal, Hubert; Lefai, Etienne; Némoz, Georges

    2013-01-01

    mTOR is a major actor of skeletal muscle mass regulation in situations of atrophy or hypertrophy. It is established that Phospholipase D (PLD) activates mTOR signaling, through the binding of its product phosphatidic acid (PA) to mTOR protein. An influence of PLD on muscle cell size could thus be suspected. We explored the consequences of altered expression and activity of PLD isoforms in differentiated L6 myotubes. Inhibition or down-regulation of the PLD1 isoform markedly decreased myotube ...

  8. Phospholipase D regulates the size of skeletal muscle cells through the activation of mTOR signaling.

    OpenAIRE

    Jaafar, Rami; De Larichaudy, Joffrey; Chanon, Stéphanie; Euthine, Vanessa; Durand, Christine; Naro, Fabio; Bertolino, Philippe; Vidal, Hubert; Lefai, Etienne; Némoz, Georges

    2013-01-01

    International audience mTOR is a major actor of skeletal muscle mass regulation in situations of atrophy or hypertrophy. It is established that Phospholipase D (PLD) activates mTOR signaling, through the binding of its product phosphatidic acid (PA) to mTOR protein. An influence of PLD on muscle cell size could thus be suspected. We explored the consequences of altered expression and activity of PLD isoforms in differentiated L6 myotubes. Inhibition or down-regulation of the PLD1 isoform m...

  9. The Effect of Alcohols on Red Blood Cell Mechanical Properties and Membrane Fluidity Depends on Their Molecular Size

    OpenAIRE

    Melda Sonmez; Huseyin Yavuz Ince; Ozlem Yalcin; Vladimir Ajdžanović; Ivan Spasojević; Meiselman, Herbert J.; Baskurt, Oguz K.

    2013-01-01

    The Effect of Alcohols on Red Blood Cell Mechanical Properties and Membrane Fluidity Depends on Their Molecular Size Melda Sonmez1, Huseyin Yavuz Ince1, Ozlem Yalcin1, Vladimir Ajdžanović2, Ivan Spasojević3, Herbert J. Meiselman4*, Oguz K. Baskurt1 1 Koc University, School of Medicine, Istanbul, Turkey, 2 University of Belgrade, Institute for Biological Research “Siniša Stanković”, Belgrade, Serbia, 3 University of Belgrade, Institute for Multidisciplinary Research, Belgrade...

  10. A Monte Carlo study of size and angular properties of a three-dimensional Poisson-Delaunay cell

    Science.gov (United States)

    Kumar, Susmit; Kurtz, Stewart K.

    1994-05-01

    On the basis of simulation of 1.2×106 three-dimensional Poisson-Delaunay cells, the statistical properties of their size and angular parameters have been studied. The moments of the volume, face area, and edge length distributions are found to be equal to those obtained from the exact expressions of Miles and of Moller. The volume, surface area, and face area distributions can be described by the two-parameter gamma distribution. The normal distribution can be used to describe the distributions of the total edge length of a cell and the perimeter of a face. The edge length distribution has also been studied. The distribution of the angle in a face is found to be in accordance with its theoretical distribution.

  11. Interplay of nanoscale domain purity and size on charge transport and recombination dynamics in polymer solar cells

    Science.gov (United States)

    Venkatesan, Swaminathan; Adhikari, Nirmal; Chen, Jihua; Ngo, Evan C.; Dubey, Ashish; Galipeau, David W.; Qiao, Qiquan

    2013-12-01

    Charge transport and bimolecular recombination dynamics were correlated with nanomorphology in polymer solar cells. The morphology of poly(diketopyrrolopyrrole-terthiophene) (PDPP3T) and phenyl-C61-butyric acid methyl ester (PC60BM) blend films was modified using different solvent additives namely 1-chloronaphthalene (CN), 1,8-diiodooctane (DIO) and 1,8-octanedithiol (ODT) and their role on steady state and transient optoelectronic properties was investigated. The energy filtered transmission electron microscopy (EFTEM) images showed that additives (e.g. CN and DIO) improved the domain purity which leads to significantly higher short circuit current densities (Jsc). However when the cells were processed with the ODT additive, the fill factor (FF) and open circuit voltage (Voc) decreased dramatically. Films processed with the ODT additive showed a smaller domain size but were more connected compared to films processed using CN and DIO additives. Transient photocurrent analysis indicates faster charge collection in the case of CN and DIO processed solar cells and the slowest charge collection in ODT processed solar cells. Interestingly devices processed with the ODT additive also showed the longest charge carrier recombination lifetime and lowest bimolecular recombination coefficient. This is attributed to the smaller donor domains that are connected with each other to provide a more interconnected and efficient charge transport matrix but longer pathways in ODT films. Such a matrix helped the charge to escape from the donor-acceptor interfaces and thus reduces the bimolecular recombination, while the longer pathway increases the charge collection time. Further insight is provided into the selection of processing conditions to achieve an ideal active layer morphology consisting of domains with higher polymer purity and optimal size that lead to higher Jsc and FF.Charge transport and bimolecular recombination dynamics were correlated with nanomorphology in polymer

  12. A novel nano-sized bionic function interface for enhancing the ability of red blood cells to carry oxygen

    International Nuclear Information System (INIS)

    A nano-sized bionic function interface was prepared by immobilizing red blood cells onto a silver electrode, which was modified with cysteamine and colloidal gold. Scanning electron microscopy and electrochemical impedance spectroscopy were used to characterize its surface. Cyclic voltammograms in phosphate buffer solution of pH 7.0 exhibited a pair of redox peaks for oxygen at -378 and -207 mV, respectively. The reduction peak currents at -378 mV were linearly proportional to the oxygen concentration in the range from 12.6 μM to 1.39 mM. Cyclic voltammetry also indicated that the functional surface enhanced the ability of red blood cells to transport oxygen. (author)

  13. The BAR Domain Protein PICK1 Controls Vesicle Number and Size in Adrenal Chromaffin Cells

    DEFF Research Database (Denmark)

    da Silva Pinheiro, Paulo César; Jansen, Anna M; de Wit, Heidi;

    2014-01-01

    Protein Interacting with C Kinase 1 (PICK1) is a Bin/Amphiphysin/Rvs (BAR) domain protein involved in AMPA receptor trafficking. Here, we identify a selective role for PICK1 in the biogenesis of large, dense core vesicles (LDCVs) in mouse chromaffin cells. PICK1 colocalized with syntaxin-6, a......, consistent with an upstream role for PICK1. Disrupting lipid binding of the BAR domain (2K-E mutation) or of the PDZ domain (CC-GG mutation) was sufficient to reproduce the secretion phenotype of the null mutant. The same mutations are known to eliminate PICK1 function in receptor trafficking, indicating...

  14. Mutations in Traf3ip1 reveal defects in ciliogenesis, embryonic development, and altered cell size regulation.

    Science.gov (United States)

    Berbari, Nicolas F; Kin, Nicholas W; Sharma, Neeraj; Michaud, Edward J; Kesterson, Robert A; Yoder, Bradley K

    2011-12-01

    Tumor necrosis factor alpha receptor 3 interacting protein 1 (Traf3ip1), also known as MIPT3, was initially characterized through its interactions with tubulin, actin, TNFR-associated factor-3 (Traf3), IL-13R1, and DISC1. It functions as an inhibitor of IL-13-mediated phosphorylation of Stat6 and in sequestration of Traf3 and DISC1 to the cytoskeleton. Studies of the Traf3ip1 homologs in C. elegans (DYF-11), Zebrafish (elipsa), and Chlamydomonas (IFT54) revealed that the protein localizes to the cilium and is required for ciliogenesis. Similar localization data has now been reported for mammalian Traf3ip1. This raises the possibility that Traf3ip1 has an evolutionarily conserved role in mammalian ciliogenesis in addition to its previously indicated functions. To evaluate this possibility, a Traf3ip1 mutant mouse line was generated. Traf3ip1 mutant cells are unable to form cilia. Homozygous Traf3ip1 mutant mice are not viable and have both neural developmental defects and polydactyly, phenotypes typical of mouse mutants with ciliary assembly defects. Furthermore, in Traf3ip1 mutants the hedgehog pathway is disrupted, as evidenced by abnormal dorsal-ventral neural tube patterning and diminished expression of a hedgehog reporter. Analysis of the canonical Wnt pathway indicates that it was largely unaffected; however, specific domains in the pharyngeal arches have elevated levels of reporter activity. Interestingly, Traf3ip1 mutant embryos and cells failed to show alterations in IL-13 signaling, one of the pathways associated with its initial discovery. Novel phenotypes observed in Traf3ip1 mutant cells include elevated cytosolic levels of acetylated microtubules and a marked increase in cell size in culture. The enlarged Traf3ip1 mutant cell size was associated with elevated basal mTor pathway activity. Taken together, these data demonstrate that Traf3ip1 function is highly conserved in ciliogenesis and is important for proper regulation of a number of essential

  15. Novel focal point multipass cell for absorption spectroscopy on small sized atmospheric pressure plasmas

    Science.gov (United States)

    Winter, Jörn; Hänel, Mattis; Reuter, Stephan

    2016-04-01

    A novel focal point multipass cell (FPMPC) was developed, in which all laser beams propagate through a common focal point. It is exclusively constructed from standard optical elements. Main functional elements are two 90∘ off-axis parabolic mirrors and two retroreflectors. Up to 17 laser passes are demonstrated with a near-infrared laser beam. The number of laser passes is precisely adjustable by changing the retroreflector distance. At the focal point beams are constricted to fit through an aperture of 0.8 mm. This is shown for 11 beam passes. Moreover, the fast temporal response of the cell permits investigation of transient processes with frequencies up to 10 MHz. In order to demonstrate the applicability of the FPMPC for atmospheric pressure plasma jets, laser absorption spectroscopy on the lowest excited argon state (1s5) was performed on a 1 MHz argon atmospheric pressure plasma jet. From the obtained optical depth profiles, the signal-to-noise ratio was deduced. It is shown that an elevation of the laser pass number results in an proportional increase of the signal-to-noise ratio making the FPMPC an appropriate tool for absorption spectroscopy on plasmas of small dimensions.

  16. Unveiling the Metabolic Pathways Associated with the Adaptive Reduction of Cell Size During Vibrio harveyi Persistence in Seawater Microcosms.

    Science.gov (United States)

    Kaberdin, Vladimir R; Montánchez, Itxaso; Parada, Claudia; Orruño, Maite; Arana, Inés; Barcina, Isabel

    2015-10-01

    Owing to their ubiquitous presence and ability to act as primary or opportunistic pathogens, Vibrio species greatly contribute to the diversity and evolution of marine ecosystems. This study was aimed at unveiling the cellular strategies enabling the marine gammaproteobacterium Vibrio harveyi to adapt and persist in natural aquatic systems. We found that, although V. harveyi incubation in seawater microcosm at 20 °C for 2 weeks did not change cell viability and culturability, it led to a progressive reduction in the average cell size. Microarray analysis revealed that this morphological change was accompanied by a profound decrease in gene expression affecting the central carbon metabolism, major biosynthetic pathways, and energy production. In contrast, V. harveyi elevated expression of genes closely linked to the composition and function of cell envelope. In addition to triggering lipid degradation via the β-oxidation pathway and apparently promoting the use of endogenous fatty acids as a major energy and carbon source, V. harveyi upregulated genes involved in ancillary mechanisms important for sustaining iron homeostasis, cell resistance to the toxic effect of reactive oxygen species, and recycling of amino acids. The above adaptation mechanisms and morphological changes appear to represent the major hallmarks of the initial V. harveyi response to starvation. PMID:25903990

  17. Renal cell carcinoma of clear type: correlation of CT features with tumor size, architectural patterns, and pathologic staging

    International Nuclear Information System (INIS)

    The purpose of this study was to report the CT findings of renal cell carcinoma of clear type (RCCCT) and to determine if there are characteristic morphologic features in RCCCT with respect to tumor size, architectural patterns, and pathologic stage. The CT scans of 35 patients with RCCCT were reviewed retrospectively. The CT findings (tumor size, attenuation patterns, presence of calcifications, encapsulation, margins of neoplasms, venous involvement by neoplasms) were correlated with tumor size, architectural patterns, and pathologic staging. Of the 35 neoplasms, 28 (80 %) were solid, 4 (11 %) were papillary, and 3 (9 %) were cystic. Complete encapsulation was more frequent in lower pathologic stages (40 % in stages 1 and 2 vs 0 % in stages 3 and 4; p < 0.05). Venous involvement was less frequent with completely encapsulated neoplasms (0 of 10, 0 %) than with incompletely or nonencapsulated neoplasms (8 of 25, 32 %; p < 0.05). Encapsulated RCCCT are more likely to have lower pathologic stage. Nonencapsulated neoplasms are more likely to have a higher pathologic stage. (orig.). With 4 figs., 3 tabs

  18. Size-controlled anatase titania single crystals with octahedron-like morphology for dye-sensitized solar cells.

    Science.gov (United States)

    Shiu, Jia-Wei; Lan, Chi-Ming; Chang, Yu-Cheng; Wu, Hui-Ping; Huang, Wei-Kai; Diau, Eric Wei-Guang

    2012-12-21

    A simple hydrothermal method with titanium tetraisopropoxide (TTIP) as a precursor and triethanolamine (TEOA) as a chelating agent enabled growth in the presence of a base (diethylamine, DEA) of anatase titania nanocrystals (HD1-HD5) of controlled size. DEA played a key role to expedite this growth, for which a biphasic crystal growth mechanism is proposed. The produced single crystals of titania show octahedron-like morphology with sizes in a broad range of 30-400 nm; a typical, extra large, octahedral single crystal (HD5) of length 410 nm and width 260 nm was obtained after repeating a sequential hydrothermal treatment using HD3 and then HD4 as a seed crystal. The nanocrystals of size ~30 nm (HD1) and ~300 nm (HD5) served as active layer and scattering layer, respectively, to fabricate N719-sensitized solar cells. These HD devices showed greater V(OC) than devices of conventional nanoparticle (NP) type; the overall device performance of HD attained an efficiency of 10.2% power conversion at a total film thickness of 28 μm, which is superior to that of a NP-based reference device (η = 9.6%) optimized at a total film thickness of 18-20 μm. According to results obtained from transient photoelectric and charge extraction measurements, this superior performance of HD devices relative to their NP counterparts is due to the more rapid electron transport and greater TiO(2) potential. PMID:23116194

  19. Efficient internalization of silica-coated iron oxide nanoparticles of different sizes by primary human macrophages and dendritic cells

    International Nuclear Information System (INIS)

    Engineered nanoparticles are being considered for a wide range of biomedical applications, from magnetic resonance imaging to 'smart' drug delivery systems. The development of novel nanomaterials for biomedical applications must be accompanied by careful scrutiny of their biocompatibility. In this regard, particular attention should be paid to the possible interactions between nanoparticles and cells of the immune system, our primary defense system against foreign invasion. On the other hand, labeling of immune cells serves as an ideal tool for visualization, diagnosis or treatment of inflammatory processes, which requires the efficient internalization of the nanoparticles into the cells of interest. Here, we compare novel monodispersed silica-coated iron oxide nanoparticles with commercially available dextran-coated iron oxide nanoparticles. The silica-coated iron oxide nanoparticles displayed excellent magnetic properties. Furthermore, they were non-toxic to primary human monocyte-derived macrophages at all doses tested whereas dose-dependent toxicity of the smaller silica-coated nanoparticles (30 nm and 50 nm) was observed for primary monocyte-derived dendritic cells, but not for the similarly small dextran-coated iron oxide nanoparticles. No macrophage or dendritic cell secretion of pro-inflammatory cytokines was observed upon administration of nanoparticles. The silica-coated iron oxide nanoparticles were taken up to a significantly higher degree when compared to the dextran-coated nanoparticles, irrespective of size. Cellular internalization of the silica-coated nanoparticles was through an active, actin cytoskeleton-dependent process. We conclude that these novel silica-coated iron oxide nanoparticles are promising materials for medical imaging, cell tracking and other biomedical applications.

  20. Migration Speed of Cajal-Retzius Cells Modulated by Vesicular Trafficking Controls the Size of Higher-Order Cortical Areas.

    Science.gov (United States)

    Barber, Melissa; Arai, Yoko; Morishita, Yoshihiro; Vigier, Lisa; Causeret, Frédéric; Borello, Ugo; Ledonne, Fanny; Coppola, Eva; Contremoulins, Vincent; Pfrieger, Frank W; Tissir, Fadel; Govindan, Subashika; Jabaudon, Denis; Proux-Gillardeaux, Véronique; Galli, Thierry; Pierani, Alessandra

    2015-10-01

    In the neocortex, higher-order areas are essential to integrate sensory-motor information and have expanded in size during evolution. How higher-order areas are specified, however, remains largely unknown. Here, we show that the migration and distribution of early-born neurons, the Cajal-Retzius cells (CRs), controls the size of higher-order areas in the mouse somatosensory, auditory, and visual cortex. Using live imaging, genetics, and in silico modeling, we show that subtype-specific differences in the onset, speed, and directionality of CR migration determine their differential invasion of the developing cortical surface. CR migration speed is cell autonomously modulated by vesicle-associated membrane protein 3 (VAMP3), a classically non-neuronal mediator of endosomal recycling. Increasing CR migration speed alters their distribution in the developing cerebral cortex and leads to an expansion of postnatal higher-order areas and congruent rewiring of thalamo-cortical input. Our findings thus identify novel roles for neuronal migration and VAMP3-dependent vesicular trafficking in cortical wiring. PMID:26387718

  1. A p53-dependent response limits epidermal stem cell functionality and organismal size in mice with short telomeres.

    Directory of Open Access Journals (Sweden)

    Ignacio Flores

    Full Text Available Telomere maintenance is essential to ensure proper size and function of organs with a high turnover. In particular, a dwarf phenotype as well as phenotypes associated to premature loss of tissue regeneration, including the skin (hair loss, hair graying, decreased wound healing, are found in mice deficient for telomerase, the enzyme responsible for maintaining telomere length. Coincidental with the appearance of these phenotypes, p53 is found activated in several tissues from these mice, where is thought to trigger cellular senescence and/or apoptotic responses. Here, we show that p53 abrogation rescues both the small size phenotype and restitutes the functionality of epidermal stem cells (ESC of telomerase-deficient mice with dysfunctional telomeres. In particular, p53 ablation restores hair growth, skin renewal and wound healing responses upon mitogenic induction, as well as rescues ESCmobilization defects in vivo and defective ESC clonogenic activity in vitro. This recovery of ESC functions is accompanied by a downregulation of senescence markers and an increased proliferation in the skin and kidney of telomerase-deficient mice with critically short telomeres without changes in apoptosis rates. Together, these findings indicate the existence of a p53-dependent senescence response acting on stem/progenitor cells with dysfunctional telomeres that is actively limiting their contribution to tissue regeneration, thereby impinging on tissue fitness.

  2. Skp2 knockout reduces cell proliferation and mouse body size: and prevents cancer?

    Institute of Scientific and Technical Information of China (English)

    Liang Zhu

    2010-01-01

    Attaching multiple ubiquitins (a 76-residue protein ubiquitously expressed in eukaryotic cells) covalently to a protein labels that protein for degradation in the proteasome (a large tunnel-like complex considered as a protein degradation factory). There are many types of ubiquitin ligases (the enzymes that carry out the protein ubiquitination reactions); one of them is the Culin-RING ubiquitin ligase (CRL). There are six Culin proteins and two RING proteins, forming six general types of Culin-RING core platforms for various substrate-recruiting subunits to complete the formation of substrate-specific CRLs. The SCF type CRL is formed with Rbx 1 (a RING protein), Skpl, Cull, and an F-box protein.

  3. Adipose Cell Size and Regional Fat Deposition as Predictors of Metabolic Response to Overfeeding in Insulin-Resistant and Insulin-Sensitive Humans.

    Science.gov (United States)

    McLaughlin, Tracey; Craig, Colleen; Liu, Li-Fen; Perelman, Dalia; Allister, Candice; Spielman, Daniel; Cushman, Samuel W

    2016-05-01

    Obesity is associated with insulin resistance, but significant variability exists between similarly obese individuals, pointing to qualitative characteristics of body fat as potential mediators. To test the hypothesis that obese, insulin-sensitive (IS) individuals possess adaptive adipose cell/tissue responses, we measured subcutaneous adipose cell size, insulin suppression of lipolysis, and regional fat responses to short-term overfeeding in BMI-matched overweight/obese individuals classified as IS or insulin resistant (IR). At baseline, IR subjects exhibited significantly greater visceral adipose tissue (VAT), intrahepatic lipid (IHL), plasma free fatty acids, adipose cell diameter, and percentage of small adipose cells. With weight gain (3.1 ± 1.4 kg), IR subjects demonstrated no significant change in adipose cell size, VAT, or insulin suppression of lipolysis and only 8% worsening of insulin-mediated glucose uptake (IMGU). Alternatively, IS subjects demonstrated significant adipose cell enlargement; decrease in the percentage of small adipose cells; increase in VAT, IHL, and lipolysis; 45% worsening of IMGU; and decreased expression of lipid metabolism genes. Smaller baseline adipose cell size and greater enlargement with weight gain predicted decline in IMGU, as did increase in IHL and VAT and decrease in insulin suppression of lipolysis. Weight gain in IS humans causes maladaptive changes in adipose cells, regional fat distribution, and insulin resistance. The correlation between development of insulin resistance and changes in adipose cell size, VAT, IHL, and insulin suppression of lipolysis highlight these factors as potential mediators between obesity and insulin resistance. PMID:26884438

  4. Phospholipase D regulates the size of skeletal muscle cells through the activation of mTOR signaling.

    Science.gov (United States)

    Jaafar, Rami; De Larichaudy, Joffrey; Chanon, Stéphanie; Euthine, Vanessa; Durand, Christine; Naro, Fabio; Bertolino, Philippe; Vidal, Hubert; Lefai, Etienne; Némoz, Georges

    2013-01-01

    mTOR is a major actor of skeletal muscle mass regulation in situations of atrophy or hypertrophy. It is established that Phospholipase D (PLD) activates mTOR signaling, through the binding of its product phosphatidic acid (PA) to mTOR protein. An influence of PLD on muscle cell size could thus be suspected. We explored the consequences of altered expression and activity of PLD isoforms in differentiated L6 myotubes. Inhibition or down-regulation of the PLD1 isoform markedly decreased myotube size and muscle specific protein content. Conversely, PLD1 overexpression induced muscle cell hypertrophy, both in vitro in myotubes and in vivo in mouse gastrocnemius. In the presence of atrophy-promoting dexamethasone, PLD1 overexpression or addition of exogenous PA protected myotubes against atrophy. Similarly, exogenous PA protected myotubes against TNFα-induced atrophy. Moreover, the modulation of PLD expression or activity in myotubes showed that PLD1 negatively regulates the expression of factors involved in muscle protein degradation, such as the E3-ubiquitin ligases Murf1 and Atrogin-1, and the Foxo3 transcription factor. Inhibition of mTOR by PP242 abolished the positive effects of PLD1 on myotubes, whereas modulating PLD influenced the phosphorylation of both S6K1 and Akt, which are respectively substrates of mTORC1 and mTORC2 complexes. These observations suggest that PLD1 acts through the activation of both mTORC1 and mTORC2 to induce positive trophic effects on muscle cells. This pathway may offer interesting therapeutic potentialities in the treatment of muscle wasting. PMID:23915343

  5. Different-Sized Gold Nanoparticle Activator/Antigen Increases Dendritic Cells Accumulation in Liver-Draining Lymph Nodes and CD8+ T Cell Responses.

    Science.gov (United States)

    Zhou, Qianqian; Zhang, Yulong; Du, Juan; Li, Yuan; Zhou, Yong; Fu, Qiuxia; Zhang, Jingang; Wang, Xiaohui; Zhan, Linsheng

    2016-02-23

    The lack of efficient antigen and activator delivery systems, as well as the restricted migration of dendritic cells (DCs) to secondary lymph organs, dramatically limits DC-based adoptive immunotherapy. We selected two spherical gold nanoparticle (AuNP)-based vehicles of optimal size for activator and antigen delivery. Their combination (termed the NanoAu-Cocktail) was associated with the dual targeting of CpG oligonucleotides (CpG-ODNs) and an OVA peptide (OVAp) to DC subcellular compartments, inducing enhanced antigen cross-presentation, upregulated expression of costimulatory molecules and elevated secretion of T helper1 cytokines. We demonstrated that the intravenously transfused NanoAu-Cocktail pulsed DCs showed dramatically improved in vivo homing ability to lymphoid tissues and were settled in T cell area. Especially, by tissue-distribution analysis, we found that more than 60% of lymphoid tissues-homing DCs accumulated in liver-draining lymph nodes (LLNs). The improved homing ability of NanoAu-Cocktail pulsed DCs was associated with the high expression of chemokine receptor 7 (CCR7) and rearrangement of the cytoskeletons. In addition, by antigen-specific tetramers detection, NanoAu-Cocktail pulsed DCs were proved able to elicit strong antigen-specific CD8+ T cell responses, which provided enhanced protection from viral invasions. This study highlights the importance of codelivering antigen/adjuvant using different sized gold nanoparticles to improve DC homing and therapy. PMID:26771692

  6. Short-term arsenic exposure reduces diatom cell size in biofilm communities.

    Science.gov (United States)

    Barral-Fraga, Laura; Morin, Soizic; Rovira, Marona D M; Urrea, Gemma; Magellan, Kit; Guasch, Helena

    2016-03-01

    Arsenic (As) pollution in water has important impacts for human and ecosystem health. In freshwaters, arsenate (As(V)) can be taken up by microalgae due to its similarity with phosphate molecules, its toxicity being aggravated under phosphate depletion. An experiment combining ecological and ecotoxicological descriptors was conducted to investigate the effects of As(V) (130 μg L(-1) over 13 days) on the structure and function of fluvial biofilm under phosphate-limiting conditions. We further incorporated fish (Gambusia holbrooki) into our experimental system, expecting fish to provide more available phosphate for algae and, consequently, protecting algae against As toxicity. However, this protection role was not fully achieved. Arsenic inhibited algal growth and productivity but not bacteria. The diatom community was clearly affected showing a strong reduction in cell biovolume; selection for tolerant species, in particular Achnanthidium minutissimum; and a reduction in species richness. Our results have important implications for risk assessment, as the experimental As concentration used was lower than acute toxicity criteria established by the USEPA. PMID:26141976

  7. The cell size and distribution of adipocytes from subcutaneous and visceral fat is associated with type 2 diabetes mellitus in humans

    OpenAIRE

    Fang, Lingling; Guo, Fangjian; ZHOU, LIHUA; Stahl, Richard; Grams, Jayleen

    2015-01-01

    Aims/hypothesis: Regional deposition of adipose tissue and adipocyte morphology may contribute to increased risk for insulin resistance. The aim of this study was to compare adipocyte cell size and size distribution from multiple fat depots and to determine the association with type 2 diabetes mellitus, anthropomorphic data, and subjects' metabolic profile.

  8. Exosomes Secreted by Human-Induced Pluripotent Stem Cell-Derived Mesenchymal Stem Cells Repair Critical-Sized Bone Defects through Enhanced Angiogenesis and Osteogenesis in Osteoporotic Rats

    Science.gov (United States)

    Qi, Xin; Zhang, Jieyuan; Yuan, Hong; Xu, Zhengliang; Li, Qing; Niu, Xin; Hu, Bin; Wang, Yang; Li, Xiaolin

    2016-01-01

    Bone defects caused by trauma, severe infection, tumor resection and skeletal abnormalities are common osteoporotic conditions and major challenges in orthopedic surgery, and there is still no effective solution to this problem. Consequently, new treatments are needed to develop regeneration procedures without side effects. Exosomes secreted by mesenchymal stem cells (MSCs) derived from human induced pluripotent stem cells (hiPSCs, hiPSC-MSC-Exos) incorporate the advantages of both MSCs and iPSCs with no immunogenicity. However, there are no reports on the application of hiPSC-MSC-Exos to enhance angiogenesis and osteogenesis under osteoporotic conditions. HiPSC-MSC-Exos were isolated and identified before use. The effect of hiPSC-MSC-Exos on the proliferation and osteogenic differentiation of bone marrow MSCs derived from ovariectomized (OVX) rats (rBMSCs-OVX) in vitro were investigated. In vivo, hiPSC-MSC-Exos were implanted into critical size bone defects in ovariectomized rats, and bone regeneration and angiogenesis were examined by microcomputed tomography (micro-CT), sequential fluorescent labeling analysis, microfil perfusion and histological and immunohistochemical analysis. The results in vitro showed that hiPSC-MSC-Exos enhanced cell proliferation and alkaline phosphatase (ALP) activity, and up-regulated mRNA and protein expression of osteoblast-related genes in rBMSCs-OVX. In vivo experiments revealed that hiPSC-MSC-Exos dramatically stimulated bone regeneration and angiogenesis in critical-sized calvarial defects in ovariectomized rats. The effect of hiPSC-MSC-Exos increased with increasing concentration. In this study, we showed that hiPSC-MSC-Exos effectively stimulate the proliferation and osteogenic differentiation of rBMSCs-OVX, with the effect increasing with increasing exosome concentration. Further analysis demonstrated that the application of hiPSC-MSC-Exos+β-TCP scaffolds promoted bone regeneration in critical-sized calvarial defects by

  9. Cell and nanoparticle transport in tumour microvasculature: the role of size, shape and surface functionality of nanoparticles.

    Science.gov (United States)

    Li, Ying; Lian, Yanping; Zhang, Lucy T; Aldousari, Saad M; Hedia, Hassan S; Asiri, Saeed A; Liu, Wing Kam

    2016-02-01

    Through nanomedicine, game-changing methods are emerging to deliver drug molecules directly to diseased areas. One of the most promising of these is the targeted delivery of drugs and imaging agents via drug carrier-based platforms. Such drug delivery systems can now be synthesized from a wide range of different materials, made in a number of different shapes, and coated with an array of different organic molecules, including ligands. If optimized, these systems can enhance the efficacy and specificity of delivery compared with those of non-targeted systems. Emerging integrated multiscale experiments, models and simulations have opened the door for endless medical applications. Current bottlenecks in design of the drug-carrying particles are the lack of knowledge about the dispersion of these particles in the microvasculature and of their subsequent internalization by diseased cells (Bao et al. 2014 J. R. Soc. Interface 11, 20140301 (doi:10.1098/rsif.2014.0301)). We describe multiscale modelling techniques that study how drug carriers disperse within the microvasculature. The immersed molecular finite-element method is adopted to simulate whole blood including blood plasma, red blood cells and nanoparticles. With a novel dissipative particle dynamics method, the beginning stages of receptor-driven endocytosis of nanoparticles can be understood in detail. Using this multiscale modelling method, we elucidate how the size, shape and surface functionality of nanoparticles will affect their dispersion in the microvasculature and subsequent internalization by targeted cells. PMID:26855759

  10. Influence of Battery/Ultracapacitor Energy-Storage Sizing on Battery Lifetime in a Fuel Cell Hybrid Electric Vehicle

    DEFF Research Database (Denmark)

    Schaltz, Erik; Rasmussen, Peter Omand; Khaligh, Alireza

    2009-01-01

    Combining high-energy-density batteries and high-power-density ultracapacitors in fuel cell hybrid electric vehicles (FCHEVs) results in a high-performance, highly efficient, low-size, and light system. Often, the battery is rated with respect to its energy requirement to reduce its volume and mass....... This does not prevent deep discharges of the battery, which are critical to the lifetime of the battery. In this paper, the ratings of the battery and ultracapacitors are investigated. Comparisons of the system volume, the system mass, and the lifetime of the battery due to the rating of the energy...... stack, the battery, and the ultracapacitors, are proposed. A charging strategy, which charges the energy-storage devices due to the conditions of the FCHEV, is also proposed. The analysis provides recommendations on the design of the battery and the ultracapacitor energy-storage systems for FCHEVs....

  11. Variability of DTM-derived, morphometric parameters versus cell size. An example of application in Calabria (Southern Italy)

    Science.gov (United States)

    Rago, Valeria; Caloiero, Paola; Pellegrino, Annamaria Daniela; Iovine, Giulio G. R.; Terranova, Oreste G.; Pascale, Stefania

    2016-04-01

    Applications of DTM-derived morphometry are nowadays common in many fields of land-use planning, including the protection from natural hazards (cf. e.g. Iovine et al. 2013; 2014). For example, the mathematical modelling of physical processes that occur at slope or basin scales makes extensive use of quantitative parameters that describe the shape of Earth surface. Unfortunately, the values of these parameters depend on the detail with which the territory is represented. Therefore, different relationships must be adopted to describe the same physical processes at different scales. In this study, as part of a wide-ranging research aimed at modelling of geo-hydrological processes, a systematic and rigorous assessment of variability of the morphometric parameters against cell sizes is addressed. The study area under consideration is the whole Calabrian territory, extended about 15075 square kilometres. The region has recently been zoned into eleven homogeneous geomorphological sectors (Antronico et al., 2010). For each geomorphological sector, DTMs have been derived from topographic maps at 1:5000 scale, with cell sizes of 5, 10, 20 and 40 m. The following morphometric parameters - among those most frequently used in land management - have then been evaluated for the above DTMs: altitude, steepness of slope, aspect, plan and profile curvatures, slope length, topographical wetness index, stream power index, topographic position index, terrain ruggedness index, slope length factor. The first results show a marked dependence on cell size for some of the considered parameters. In other cases, such dependence seems not significant. Mathematical relationships are proposed between cell size and considered parameters, also taking into account the geomorphological contexts examined. Based on the above relationships, the most suitable scale to be used for modelling physical processes in a given area of interest can be selected. References Antronico L., L. Borselli, R. Coscarelli

  12. Ellipsometry analysis of a-Si:H solar cell structures with submicron-size textures using glass-side illumination

    International Nuclear Information System (INIS)

    Hydrogenated amorphous silicon (a-Si:H) solar cell structures with submicron-size textures have been determined by spectroscopic ellipsometry (SE) measurements, in which the probe light illuminates the glass/SnO2:F/a-Si:H/ZnO:Al/Ag structure from the glass-substrate side. To analyze the inhomogeneous solar cell structures due to random textures, we applied an optical model having two regions with different layer thicknesses. The optical response of the rough interface regions in the textured structures is expressed using the multilayer optical structure, in which the variation of the multiphase compositions toward the depth direction is modeled by a power function. Although only the specular reflection has been considered in the SE analysis, the ellipsometry spectra calculated from our optical model show excellent agreement with the measured spectra, as the diffused light induced by the rough textures has not been detected in our measurement configuration. Furthermore, the layer thicknesses deduced from the SE analysis agree quite well with those evaluated by transmission electron microscopy. Using the SE analysis method developed in this study, the non-destructive structural characterization of large-area a-Si:H solar cell modules can be made by illuminating with the SE probe light from the glass-substrate side. - Highlights: • Textured a-Si:H solar cell structures have been characterized by ellipsometry. • In the measurement, the probe light is illuminated from the glass substrate side. • The inhomogeneous and textured structures are expressed by a new optical model. • The film structures deduced from the analysis agree well with those evaluated by TEM

  13. Variability in bioreactivity linked to changes in size and zeta potential of diesel exhaust particles in human immune cells.

    Directory of Open Access Journals (Sweden)

    Srijata Sarkar

    Full Text Available Acting as fuel combustion catalysts to increase fuel economy, cerium dioxide (ceria, CeO2 nanoparticles have been used in Europe as diesel fuel additives (Envirox™. We attempted to examine the effects of particles emitted from a diesel engine burning either diesel (diesel exhaust particles, DEP or diesel doped with various concentrations of CeO2 (DEP-Env on innate immune responses in THP-1 and primary human peripheral blood mononuclear cells (PBMC. Batches of DEP and DEP-Env were obtained on three separate occasions using identical collection and extraction protocols with the aim of determining the reproducibility of particles generated at different times. However, we observed significant differences in size and surface charge (zeta potential of the DEP and DEP-Env across the three batches. We also observed that exposure of THP-1 cells and PBMC to identical concentrations of DEP and DEP-Env from the three batches resulted in statistically significant differences in bioreactivity as determined by IL-1β, TNF-α, IL-6, IFN-γ, and IL-12p40 mRNA (by qRT-PCR and protein expression (by ELISPOT assays. Importantly, bioreactivity was noted in very tight ranges of DEP size (60 to 120 nm and zeta potential (-37 to -41 mV. Thus, these physical properties of DEP and DEP-Env were found to be the primary determinants of the bioreactivity measured in this study. Our findings also point to the potential risk of over- or under- estimation of expected bioreactivity effects (and by inference of public health risks from bulk DEP use without taking into account potential batch-to-batch variations in physical (and possibly chemical properties.

  14. The effect of alcohols on red blood cell mechanical properties and membrane fluidity depends on their molecular size.

    Directory of Open Access Journals (Sweden)

    Melda Sonmez

    Full Text Available The role of membrane fluidity in determining red blood cell (RBC deformability has been suggested by a number of studies. The present investigation evaluated alterations of RBC membrane fluidity, deformability and stability in the presence of four linear alcohols (methanol, ethanol, propanol and butanol using ektacytometry and electron paramagnetic resonance (EPR spectroscopy. All alcohols had a biphasic effect on deformability such that it increased then decreased with increasing concentration; the critical concentration for reversal was an inverse function of molecular size. EPR results showed biphasic changes of near-surface fluidity (i.e., increase then decrease and a decreased fluidity of the lipid core; rank order of effectiveness was butanol > propanol > ethanol > methanol, with a significant correlation between near-surface fluidity and deformability (r = 0.697; p<0.01. The presence of alcohol enhanced the impairment of RBC deformability caused by subjecting cells to 100 Pa shear stress for 300 s, with significant differences from control being observed at higher concentrations of all four alcohols. The level of hemolysis was dependent on molecular size and concentration, whereas echinocytic shape transformation (i.e., biconcave disc to crenated morphology was observed only for ethanol and propanol. These results are in accordance with available data obtained on model membranes. They document the presence of mechanical links between RBC deformability and near-surface membrane fluidity, chain length-dependence of the ability of alcohols to alter RBC mechanical behavior, and the biphasic response of RBC deformability and near-surface membrane fluidity to increasing alcohol concentrations.

  15. Large Size Color-tunable Electroluminescence from Cationic Iridium Complexes-based Light-emitting Electrochemical Cells

    Science.gov (United States)

    Zeng, Qunying; Li, Fushan; Guo, Tailiang; Shan, Guogang; Su, Zhongmin

    2016-06-01

    Solution-processable light-emitting electrochemical cells (LECs) with simple device architecture have become an attractive candidate for application in next generation lighting and flat-panel displays. Herein, single layer LECs employing two cationic Ir(III) complexes showing highly efficient blue-green and yellow electroluminescence with peak current efficiency of 31.6 cd A‑1 and 40.6 cd A‑1, respectively, have been reported. By using both complexes in the device, color-tunable LECs with a single spectral peak in the wavelength range from 499 to 570 nm were obtained by varying their rations. In addition, the fabrication of efficient LECs was demonstrated based on low cost doctor-blade coating technique, which was compatible with the roll to roll fabrication process for the large size production. In this work, for the first time, 4 inch LEC devices by doctor-blade coating were fabricated, which exhibit the efficiencies of 23.4 cd A‑1 and 25.4 cd A‑1 for the blue-green and yellow emission, respectively. The exciting results indicated that highly efficient LECs with controllable color could be realized and find practical application in large size lighting and displays.

  16. Detonation cell size measurements in high-temperature hydrogen-air-steam mixtures at the BNL high-temperature combustion facility

    International Nuclear Information System (INIS)

    The High-Temperature Combustion Facility (HTCF) was designed and constructed with the objective of studying detonation phenomena in mixtures of hydrogen-air-steam at initially high temperatures. The central element of the HTCF is a 27-cm inner-diameter, 21.3-m long cylindrical test vessel capable of being heating to 700K ± 14K. A unique feature of the HTCF is the 'diaphragmless' acetylene-oxygen gas driver which is used to initiate the detonation in the test gas. Cell size measurements have shown that for any hydrogen-air-steam mixture, increasing the initial mixture temperature, in the range of 300K to 650K, while maintaining the initial pressure of 0.1 MPa, decreases the cell size and thus makes the mixture more detonable. The effect of steam dilution on cell size was tested in stoichiometric and off-stoichiometric (e.g., equivalence ratio of 0.5) hydrogen-air mixtures. Increasing the steam dilution in hydrogen-air mixtures at 0.1 MPa initial pressure increases the cell size, irrespective of initial temperature. It is also observed that the desensitizing effect of steam diminished with increased initial temperature. A 1-dimensional, steady-state Zel'dovich, von Neumann, Doring (ZND) model, with full chemical kinetics, has been used to predict cell size for hydrogen-air-steam mixtures at different initial conditions. Qualitatively the model predicts the overall trends observed in the measured cell size versus mixture composition and initial temperature and pressure. It was found that the proportionality constant used to predict detonation cell size from the calculated ZND model reaction zone varies between 10 and 100 depending on the mixture composition and initial temperature. 32 refs., 35 figs

  17. Archaeal signal transduction: impact of protein phosphatase deletions on cell size, motility, and energy metabolism in Sulfolobus acidocaldarius.

    Science.gov (United States)

    Reimann, Julia; Esser, Dominik; Orell, Alvaro; Amman, Fabian; Pham, Trong Khoa; Noirel, Josselin; Lindås, Ann-Christin; Bernander, Rolf; Wright, Phillip C; Siebers, Bettina; Albers, Sonja-Verena

    2013-12-01

    In this study, the in vitro and in vivo functions of the only two identified protein phosphatases, Saci-PTP and Saci-PP2A, in the crenarchaeal model organism Sulfolobus acidocaldarius were investigated. Biochemical characterization revealed that Saci-PTP is a dual-specific phosphatase (against pSer/pThr and pTyr), whereas Saci-PP2A exhibited specific pSer/pThr activity and inhibition by okadaic acid. Deletion of saci_pp2a resulted in pronounced alterations in growth, cell shape and cell size, which could be partially complemented. Transcriptome analysis of the three strains (Δsaci_ptp, Δsaci_pp2a and the MW001 parental strain) revealed 155 genes that were differentially expressed in the deletion mutants, and showed significant changes in expression of genes encoding the archaella (archaeal motility structure), components of the respiratory chain and transcriptional regulators. Phosphoproteome studies revealed 801 unique phosphoproteins in total, with an increase in identified phosphopeptides in the deletion mutants. Proteins from most functional categories were affected by phosphorylation, including components of the motility system, the respiratory chain, and regulatory proteins. In the saci_pp2a deletion mutant the up-regulation at the transcript level, as well as the observed phosphorylation pattern, resembled starvation stress responses. Hypermotility was also observed in the saci_pp2a deletion mutant. The results highlight the importance of protein phosphorylation in regulating essential cellular processes in the crenarchaeon S. acidocaldarius. PMID:24078887

  18. Gradients in pore size enhance the osteogenic differentiation of human mesenchymal stromal cells in three-dimensional scaffolds

    Science.gov (United States)

    di Luca, Andrea; Ostrowska, Barbara; Lorenzo-Moldero, Ivan; Lepedda, Antonio; Swieszkowski, Wojcech; van Blitterswijk, Clemens; Moroni, Lorenzo

    2016-03-01

    Small fractures in bone tissue can heal by themselves, but in case of larger defects current therapies are not completely successful due to several drawbacks. A possible strategy relies on the combination of additive manufactured polymeric scaffolds and human mesenchymal stromal cells (hMSCs). The architecture of bone tissue is characterized by a structural gradient. Long bones display a structural gradient in the radial direction, while flat bones in the axial direction. Such gradient presents a variation in bone density from the cancellous bone to the cortical bone. Therefore, scaffolds presenting a gradient in porosity could be ideal candidates to improve bone tissue regeneration. In this study, we present a construct with a discrete gradient in pore size and characterize its ability to further support the osteogenic differentiation of hMSCs. Furthermore, we studied the behaviour of hMSCs within the different compartments of the gradient scaffolds, showing a correlation between osteogenic differentiation and ECM mineralization, and pore dimensions. Alkaline phosphatase activity and calcium content increased with increasing pore dimensions. Our results indicate that designing structural porosity gradients may be an appealing strategy to support gradual osteogenic differentiation of adult stem cells.

  19. Ablation of the mTORC2 component rictor in brain or Purkinje cells affects size and neuron morphology.

    Science.gov (United States)

    Thomanetz, Venus; Angliker, Nico; Cloëtta, Dimitri; Lustenberger, Regula M; Schweighauser, Manuel; Oliveri, Filippo; Suzuki, Noboru; Rüegg, Markus A

    2013-04-15

    The mammalian target of rapamycin (mTOR) assembles into two distinct multi-protein complexes called mTORC1 and mTORC2. Whereas mTORC1 is known to regulate cell and organismal growth, the role of mTORC2 is less understood. We describe two mouse lines that are devoid of the mTORC2 component rictor in the entire central nervous system or in Purkinje cells. In both lines neurons were smaller and their morphology and function were strongly affected. The phenotypes were accompanied by loss of activation of Akt, PKC, and SGK1 without effects on mTORC1 activity. The striking decrease in the activation and expression of several PKC isoforms, the subsequent loss of activation of GAP-43 and MARCKS, and the established role of PKCs in spinocerebellar ataxia and in shaping the actin cytoskeleton strongly suggest that the morphological deficits observed in rictor-deficient neurons are mediated by PKCs. Together our experiments show that mTORC2 has a particularly important role in the brain and that it affects size, morphology, and function of neurons. PMID:23569215

  20. Comparative endothelial cell response on topographically patterned titanium and silicon substrates with micrometer to sub-micrometer feature sizes.

    Directory of Open Access Journals (Sweden)

    Prashanthi Vandrangi

    Full Text Available In this work, we evaluate the in vitro response of endothelial cells (EC to variation in precisely-defined, micrometer to sub-micrometer scale topography on two different substrate materials, titanium (Ti and silicon (Si. Both substrates possess identically-patterned surfaces composed of microfabricated, groove-based gratings with groove widths ranging from 0.5 to 50 µm, grating pitch twice the groove width, and groove depth of 1.3 µm. These specific materials are chosen due to their relevance for implantable microdevice applications, while grating-based patterns are chosen for the potential they afford for inducing elongated and aligned cellular morphologies reminiscent of the native endothelium. Using EA926 cells, a human EC variant, we show significant improvement in cellular adhesion, proliferation, morphology, and function with decreasing feature size on patterned Ti substrates. Moreover, we show similar trending on patterned Si substrates, albeit to a lesser extent than on comparably patterned Ti substrates. Collectively, these results suggest promise for sub-micrometer topographic patterning in general, and sub-micrometer patterning of Ti specifically, as a means for enhancing endothelialization and neovascularisation for novel implantable microdevice applications.

  1. Size and frequency characteristics of alpha beta and gamma delta T cells in the spleens of normal and cyclophosphamide-suppressed virus-infected chickens.

    Science.gov (United States)

    Banbura, M; Webster, R G; Cooper, M; Doherty, P C

    1991-08-01

    The characteristics of avian lymphocytes expressing surface CD8 (CT8) and T cell receptor (TCR) glycoproteins have been monitored by two-color flow microfluorimetry. Exposure of 1-month-old birds to a lethal influenza A virus, which is known to be lympholytic, significantly decreased the frequency of both the alpha beta TCR2+CT8+ and gamma delta TCR1+CT8- subsets in spleen. However, all categories of T cells showed evidence of greater mean cell size, indicating that they are responding. Inoculation of baby chicks with fowl pox virus induced a response more typical of specific immunity in the TCR2+CT8+ set, in that the lymphocytes increased in both frequency and mean cell size. Greater numbers of lymphoblasts were also found for the TCR2+CT8-, TCR1+CT8+, and TCR1+CT8- subsets, but the total cell counts for the minority TCR1+CT8- cells in spleen were consistently decreased. Immunosuppression with cyclophosphamide prior to infection eliminated 90% of the white blood cells from spleen, with the greatest effect being on the TCR1+ populations. The CT8+ alpha beta T cell response in chick spleen following exposure to a poxvirus is thus comparable to the situation observed for this subset of lymphocytes in mice infected with other viruses. However, although the gamma delta T cells increase in size, their frequency in spleen either does not change (CT8+) or is significantly decreased (CT8-). PMID:1647883

  2. Nanoporous anodic aluminum oxide with a long-range order and tunable cell sizes by phosphoric acid anodization on pre-patterned substrates

    Science.gov (United States)

    Surawathanawises, Krissada; Cheng, Xuanhong

    2014-01-01

    Nanoporous anodic aluminum oxide (AAO) has been explored for various applications due to its regular cell arrangement and relatively easy fabrication processes. However, conventional two-step anodization based on self-organization only allows the fabrication of a few discrete cell sizes and formation of small domains of hexagonally packed pores. Recent efforts to pre-pattern aluminum followed with anodization significantly improve the regularity and available pore geometries in AAO, while systematic study of the anodization condition, especially the impact of acid composition on pore formation guided by nanoindentation is still lacking. In this work, we pre-patterned aluminium thin films using ordered monolayers of silica beads and formed porous AAO in a single-step anodization in phosphoric acid. Controllable cell sizes ranging from 280 nm to 760 nm were obtained, matching the diameters of the silica nanobead molds used. This range of cell size is significantly greater than what has been reported for AAO formed in phosphoric acid in the literature. In addition, the relationships between the acid concentration, cell size, pore size, anodization voltage and film growth rate were studied quantitatively. The results are consistent with the theory of oxide formation through an electrochemical reaction. Not only does this study provide useful operational conditions of nanoindentation induced anodization in phosphoric acid, it also generates significant information for fundamental understanding of AAO formation. PMID:24535886

  3. Toxicity of benz(a)anthracene and fluoranthene to marine phytoplankton in culture: Does cell size really matter?

    Energy Technology Data Exchange (ETDEWEB)

    Othman, Hiba Ben [UMR 5119 ECOSYM, CNRS-IRD-Universite Montpellier II-Ifremer-Universite Montpellier I, SMEL 2 rue des Chantiers, F-34200 Sete (France); Laboratoire de Cytologie Vegetale et Phytoplanctonologie, Faculte des Sciences de Bizerte, Universite de Carthage, Zarzouna 7021, Bizerte (Tunisia); Leboulanger, Christophe, E-mail: christophe.leboulanger@ird.fr [UMR 5119 ECOSYM, CNRS-IRD-Universite Montpellier II-Ifremer-Universite Montpellier I, SMEL 2 rue des Chantiers, F-34200 Sete (France); Le Floc' h, Emilie [UMS MEDIMEER, CNRS-Universite Montpellier II, SMEL 2 rue des Chantiers F-34200 Sete (France); Hadj Mabrouk, Hassine; Sakka Hlaili, Asma [Laboratoire de Cytologie Vegetale et Phytoplanctonologie, Faculte des Sciences de Bizerte, Universite de Carthage, Zarzouna 7021, Bizerte (Tunisia)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Polycyclic aromatic hydrocarbons (PAHs) in the marine environment are a hazardous chemical legacy. Black-Right-Pointing-Pointer Benz(a)anthracene and fluoranthene are toxic to phytoplankton photosynthesis and growth in culture. Black-Right-Pointing-Pointer Acute (photosynthesis) and chronic (population growth) effects have different thresholds. Black-Right-Pointing-Pointer Toxicity depends on both the species selected as a model and the compound considered. Black-Right-Pointing-Pointer Further study of the size/sensitivity relationship is required to draw more general conclusions. - Abstract: The toxicity of benz(a)anthracene and fluoranthene (polycyclic aromatic hydrocarbons, PAHs) was evaluated on seven species of marine algae in culture belonging to pico-, nano-, and microphytoplankton, exposed to increasing concentrations of up to 2 mg L{sup -1}. The short-term (24 h) toxicity was assessed using chlorophyll a fluorescence transients, linked to photosynthetic parameters. The maximum quantum yield Fv/Fm was lower at the highest concentrations tested and the toxicity thresholds were species-dependent. For acute effects, fluoranthene was more toxic than benz(a)anthracene, with LOECs of 50.6 and 186 {mu}g L{sup -1}, respectively. After 72 h exposure, there was a dose-dependent decrease in cell density, fluoranthene being more toxic than benz(a)anthracene. The population endpoint at 72 h was affected to a greater extent than the photosynthetic endpoint at 24 h. EC50 was evaluated using the Hill model, and species sensitivity was negatively correlated to cell biovolume. The largest species tested, the dinoflagellate Alexandrium catenella, was almost insensitive to either PAH. The population endpoint EC50s for fluoranthene varied from 54 {mu}g L{sup -1} for the picophytoplankton Picochlorum sp. to 418 {mu}g L{sup -1} for the larger diatom Chaetoceros muelleri. The size/sensitivity relationship is proposed as a useful model when

  4. Control of lipid storage and cell size between adipocytes by vesicle-associated glycosylphosphatidylinositol-anchored proteins.

    Science.gov (United States)

    Müller, Günter

    2011-02-01

    Adipose tissue mass in mammals is expanding by increasing the average cell volume as well as the total number of the adipocytes. Up-regulation of lipid storage in fully differentiated adipocytes resulting in their enlargement is well documented and thought to be a critical mechanism for the expansion of adipose tissue depots during the growth of both lean and obese animals and human beings. A novel molecular mechanism for the regulation of lipid storage and cell size in rat adipocytes has recently been elucidated for the physiological stimuli, palmitate and hydrogen peroxide, the anti-diabetic sulfonylurea drug, glimepiride, and insulin-mimetic phosphoinositolglycans. It encompasses (i) the release of small vesicles, so-called adiposomes, harbouring the glycosylphosphatidylinositol-anchored (c)AMP-degrading phosphodiesterase Gce1 and 5'-nuceotidase CD73 from large donor adipocytes, (ii) the transfer of the adiposomes and their interaction with detergent-insoluble glycolipid-enriched microdomains of the plasma membrane of small acceptor adipocytes, (iii) the translocation of Gce1 and CD73 from the adiposomes to the intracellular lipid droplets of the acceptor adipocytes and (iv) the degradation of (c)AMP at the lipid droplet surface zone by Gce1 and CD73 in the acceptor adipocytes. In concert, this sequence of events leads to up-regulation of esterification of fatty acids into triacylglycerol and down-regulation of their release from triacylglycerol. This apparent mechanism for shifting the triacylglycerol burden from large to small adipocytes may provide novel strategies for the therapy of metabolic diseases, such as type 2 diabetes and obesity. PMID:20883086

  5. Effect of particle size and dispersion status on cytotoxicity and genotoxicity of zinc oxide in human bronchial epithelial cells.

    Science.gov (United States)

    Roszak, Joanna; Catalán, Julia; Järventaus, Hilkka; Lindberg, Hanna K; Suhonen, Satu; Vippola, Minnamari; Stępnik, Maciej; Norppa, Hannu

    2016-07-01

    Data available on the genotoxicity of zinc oxide (ZnO) nanoparticles (NPs) are controversial. Here, we examined the effects of particle size and dispersion status on the cytotoxicity and genotoxicity of nanosized and fine ZnO, in the presence and absence of bovine serum albumin (BSA; 0.06%) in human bronchial epithelial BEAS-2B cells. Dynamic light scattering analysis showed the most homogenous dispersions in water alone for nanosized ZnO and in water with BSA for fine ZnO. After a 48-h treatment, both types of ZnO were cytotoxic within a similar, narrow dose range (1.5-3.0μg/cm(2)) and induced micronuclei at a near toxic dose range (1.25-1.75μg/cm(2)), both with and without BSA. In the comet assay, nanosized ZnO (1.25-1.5μg/cm(2)), in the absence of BSA, caused a statistically significant increase in DNA damage after 3-h and 6-h treatments, while fine ZnO did not. Our findings may be explained by better uptake or faster intracellular dissolution of nanosized ZnO without BSA during short treatments (3-6h; the comet assay), with less differences between the two ZnO forms after longer treatments (>48h; the in vitro micronucleus test). As ZnO is genotoxic within a narrow dose range partly overlapping with cytotoxic doses, small experimental differences e.g. in the dispersion of ZnO particles may have a substantial effect on the genotoxicity of the nominal doses added to the cell culture. PMID:27402478

  6. Conducting transition metal nitride thin films with tailored cell sizes: The case of δ-TixTa1-xN

    International Nuclear Information System (INIS)

    We present results on the stability and tailoring of the cell size of conducting δ-TixTa1-xN obtained by film growth and ab initio calculations. Despite the limited solubility of Ta in Ti, we show that TiN and TaN are soluble due to the hybrization of the d and sp electrons of the metal and N, respectively, that stabilizes the ternary system to the rocksalt structure. The stress-free cell sizes follow the Vegard's rule; nevertheless, process-dependent stresses expand the cell size of the as-grown films. The electronic properties of δ-TixTa1-xN films (ρ=180 Ω cm) are similar to those of TiN and TaN

  7. Estimation of size of red blood cell aggregates using backscattering property of high-frequency ultrasound: In vivo evaluation

    Science.gov (United States)

    Kurokawa, Yusaku; Taki, Hirofumi; Yashiro, Satoshi; Nagasawa, Kan; Ishigaki, Yasushi; Kanai, Hiroshi

    2016-07-01

    We propose a method for assessment of the degree of red blood cell (RBC) aggregation using the backscattering property of high-frequency ultrasound. In this method, the scattering property of RBCs is extracted from the power spectrum of RBC echoes normalized by that from the posterior wall of a vein. In an experimental study using a phantom, employing the proposed method, the sizes of microspheres 5 and 20 µm in diameter were estimated to have mean values of 4.7 and 17.3 µm and standard deviations of 1.9 and 1.4 µm, respectively. In an in vivo experimental study, we compared the results between three healthy subjects and four diabetic patients. The average estimated scatterer diameters in healthy subjects at rest and during avascularization were 7 and 28 µm, respectively. In contrast, those in diabetic patients receiving both antithrombotic therapy and insulin therapy were 11 and 46 µm, respectively. These results show that the proposed method has high potential for clinical application to assess RBC aggregation, which may be related to the progress of diabetes.

  8. Effect of TiO2 Particle Size on the Performance of Flexible Dye Sensitized Solar Cells.

    Science.gov (United States)

    Li, Zhen-yu; Akhtar, M Shaheer; Yang, O-bong

    2015-09-01

    The size TiO2 nanoparticles was controlled by changing the concentration of titanium tetraisopropanolate (TTIP) and utilized as light scattering particles in the efficient flexible photoelectrodes for flexible dye sensitized solar cells (DSSCs). The flexible photoelectrodes were prepared by TiO2 nanoparticles (-25 nm) paste with different concentrations of ethanolic TTIP solution. The addition of TTIP produced the bigger TiO2 nanoparticles, which significantly enhanced the dye absorption of flexible TiO2 photoelectrode. The fabricated flexible DSSCs showed the reasonable conversion efficiency of 2.50% with short circuit current (J(sc)) of 6.3 mA/cm2, open circuit voltage (V(oc)) of 0.720 V and fill factor (FF) of 0.55. The improvement in photovoltaic performance with 25 wt% TTIP might due to uniform distribution of small TiO2 nanoparticles over the big particles to lead the enhancement in the surface area, resulting in the high dye absorption and light harvesting efficiency. PMID:26716227

  9. Microdosimetric spread for cell-sized targets exposed to 60Co, 192Ir and 125I sources

    International Nuclear Information System (INIS)

    The magnitude of the spread in specific energy deposition per cell may be a confounding factor in dose- response analysis motivating derivation of explicit data for the most common brachytherapy isotopes 125I and 192Ir, and for 60Co radiation frequently used as reference in RBE studies. The aim of this study is to analyse the microdosimetric spread as given by the frequency distribution of specific energy for a range of doses imparted by 125I, 192Ir and 60Co sources. An upgraded version of the Monte Carlo code PENELOPE was used for scoring energy deposition distributions in liquid water for each of the radiation qualities. Frequency distributions of specific energy were calculated according to the formalism of Kellerer and Chmelevsky. Results indicate that the magnitude of the microdosimetric spread increases with decreasing target size and decreasing energy of the radiation quality. Within the clinical relevant dose range (1 to 100 Gy), the spread does not exceed 4 % for 60Co, 5 % for 192Ir and 6 % for 125I. The frequency distributions can be accurately approximated with symmetrical normal distributions at doses down to 0.2 Gy for 60Co, 0.1 Gy for 192Ir and 0.08 Gy for 125I. (authors)

  10. Size dependent electron transfer from CdTe quantum dots linked to TiO2 thin films in quantum dot sensitized solar cells

    International Nuclear Information System (INIS)

    In this present study, we demonstrate the size dependent charge transfer from CdTe quantum dots (QDs) into TiO2 substrate and relate this charge transfer to the actual behavior of a CdTe sensitized solar cell. CdTe QDs was synthesized using mercaptopropionic acid as the capping agent. The conduction band offset for TiO2 and CdTe QDs indicates thermodynamically favorable band edge positions for smaller QDs for the electron-transfer at the QD–TiO2 interface. Time-resolved emission studies were carried out for CdTe QD on glass and CdTe QD on TiO2 substrates. Results on the quenching of QD luminescence, which relates to the transfer kinetics of electrons from the QD to the TiO2 film, showed that at the smaller QD sizes the transfer kinetics are much more rapid than at the larger sizes. I–V characteristics of quantum dot sensitized solar cells (QDSSC) with different sized QDs were also investigated indicating higher current densities at smaller QD sizes consistent with the charge transfer results. The maximum injection rate constant and photocurrent were obtained for 2.5 nm CdTe QDs. We have been able to construct a solar cell with reasonable characteristics (Voc = 0.8 V, Jsc = 1 mA cm−2, FF = 60%, η = 0.5%). - Highlights: • Size dependant charge transfer from quantum dots to TiO2. • Smaller quantum dot sizes promote higher current densities in solar cell. • Smaller quantum dots have favorable band edge positions and transport kinetics

  11. Brood-cell size has no influence on the population dynamics of Varroa destructor mites in the native western honey bee, Apis mellifera mellifera

    OpenAIRE

    Coffey, Mary F.; Breen, John; Brown, Mark J.F.; Mcmullan, John B.

    2010-01-01

    The varroa mite (Varroa destructor) is an ectoparasite of the western honeybee Apis mellifera that reproduces in the brood cells. The mite will generally kill colonies unless treatment is given, and this almost universally involves the use of chemicals. This study was undertaken to examine the effect of small cell size on the reproductive success of the mite, as a method of non-chemical control in the Northern European honeybee Apis mellifera mellifera. Test colonies with alternating small an...

  12. Expansion of IgG+ B-cells during mitogen stimulation for memory B-cell ELISpot analysis is influenced by size and composition of the B-cell pool.

    Science.gov (United States)

    Scholzen, Anja; Nahrendorf, Wiebke; Langhorne, Jean; Sauerwein, Robert W

    2014-01-01

    The memory B-cell (MBC) ELISpot assay is the main technique used to measure antigen-specific MBCs as a readout of humoral immune memory. This assay relies on the ability of MBCs to differentiate into antibody-secreting cells (ASC) upon polyclonal stimulation. The total number of IgG+ ASCs generated by mitogen-stimulation is often used as a reference point; alternatively antigen-specific MBCs are expressed as a frequency of post-culture peripheral blood mononuclear cells (PBMC) as a surrogate for absolute frequencies. Therefore, it is important to know whether IgG+ B-cells are uniformly expanded during the preceding mitogen-culture as a true reflection of MBC frequencies ex vivo. We systematically compared B-cell phenotype and proportions before and after mitogen stimulation in cultures of 269 peripheral blood mononuclear cell samples from 62 volunteers by flow cytometry and analyzed the number of resulting ASCs. Our data show that the number of total IgG+ ASCs detected by ELISpot after mitogen stimulation correlates with the proportion of IgG+ MBCs ex vivo, highlighting its general robustness for comparisons of study cohorts at group level. The expansion of total and IgG+ B-cells during mitogen-stimulation, however, was not identical in all cultures, but influenced by size and composition of the ex vivo B-cell compartment. The uncorrected readout of antigen-specific MBCs per million post-culture PBMCs therefore only preserves the quality, but not the magnitude of differences in the ex vivo MBC response between groups or time points, particularly when comparing samples where the B-cell compartment substantially differs between cohorts or over time. Therefore, expressing antigen-specific cells per total IgG+ ASCs is currently the best measure to correct for mitogen-culture effects. Additionally, baseline information on the size and composition of the ex vivo B-cell compartment should be supplied to additionally inform about differences or changes in the size and

  13. Expansion of IgG+ B-cells during mitogen stimulation for memory B-cell ELISpot analysis is influenced by size and composition of the B-cell pool.

    Directory of Open Access Journals (Sweden)

    Anja Scholzen

    Full Text Available The memory B-cell (MBC ELISpot assay is the main technique used to measure antigen-specific MBCs as a readout of humoral immune memory. This assay relies on the ability of MBCs to differentiate into antibody-secreting cells (ASC upon polyclonal stimulation. The total number of IgG+ ASCs generated by mitogen-stimulation is often used as a reference point; alternatively antigen-specific MBCs are expressed as a frequency of post-culture peripheral blood mononuclear cells (PBMC as a surrogate for absolute frequencies. Therefore, it is important to know whether IgG+ B-cells are uniformly expanded during the preceding mitogen-culture as a true reflection of MBC frequencies ex vivo. We systematically compared B-cell phenotype and proportions before and after mitogen stimulation in cultures of 269 peripheral blood mononuclear cell samples from 62 volunteers by flow cytometry and analyzed the number of resulting ASCs. Our data show that the number of total IgG+ ASCs detected by ELISpot after mitogen stimulation correlates with the proportion of IgG+ MBCs ex vivo, highlighting its general robustness for comparisons of study cohorts at group level. The expansion of total and IgG+ B-cells during mitogen-stimulation, however, was not identical in all cultures, but influenced by size and composition of the ex vivo B-cell compartment. The uncorrected readout of antigen-specific MBCs per million post-culture PBMCs therefore only preserves the quality, but not the magnitude of differences in the ex vivo MBC response between groups or time points, particularly when comparing samples where the B-cell compartment substantially differs between cohorts or over time. Therefore, expressing antigen-specific cells per total IgG+ ASCs is currently the best measure to correct for mitogen-culture effects. Additionally, baseline information on the size and composition of the ex vivo B-cell compartment should be supplied to additionally inform about differences or changes in

  14. Heat engines and heat pumps in a hydrostatic atmosphere: How surface pressure and temperature control wind power output and circulation cell size

    CERN Document Server

    Makarieva, A M; Nefiodov, A V; Sheil, D; Nobre, A D; Shearman, P L; Li, B -L

    2015-01-01

    The gross spatial features of the atmospheric kinetic energy budget are analytically investigated. Kinetic energy generation is evaluated in a hydrostatic atmosphere where the axisymmetric circulation cells are represented by Carnot cycles. The condition that kinetic energy generation is positive in the lower atmosphere is shown to limit the poleward cell extension via a relationship between the meridional differences in surface pressure and temperature $\\Delta p_s$ and $\\Delta T_s$: an upper limit to cell size exists when $\\Delta p_s$ increases sublinearly with $\\Delta T_s$. This is the case for the Hadley cells as demonstrated here using data from MERRA re-analysis. The limited cell size necessitates the appearance of heat pumps -- circulation cells with negative work output where the low-level air moves towards colder areas. These cells consume the positive work output of heat engines -- cells where the low-level air moves towards the warmer areas -- and can in principle drive the global efficiency of atmo...

  15. CD4+ Cell Count and HIV Load as Predictors of Size of Anal Warts Over Time in HIV-Infected Women

    OpenAIRE

    Luu, Hung N.; Amirian, E. Susan; Chan, Wenyaw; Beasley, R. Palmer; Piller, Linda B; Scheurer, Michael E.

    2012-01-01

    Background. Little is known about the associations between CD4+ cell counts, human immunodeficiency virus (HIV) load, and human papillomavirus “low-risk” types in noncancerous clinical outcomes. This study examined whether CD4+ count and HIV load predict the size of the largest anal warts in 976 HIV-infected women in an ongoing cohort.

  16. Characterization and modeling of bubbles size distribution in mechanical flotation cells; Caracterizacion y modelacion de las distribuciones de tamano de burbujas en celdas de flotacion con agitacion mecanica

    Energy Technology Data Exchange (ETDEWEB)

    Vallebuona, G.; Casali, A.; Kracht, W.

    2005-07-01

    In this work, bubble size distribution is determined for tests in a batch flotation cells, for different impeller speed and air flowrate. Bubbles are sampled and their sizes are measured using image analysis. Size distributions by surface are expressed as cumulative percent passing as well as percent retained. The distributions show a common shape for all tests and are represented with a unique model, selected due to its goodness of fit. This model corresponds to an equation used in heavy media separation and considers two parameters: x{sub 5}0, the 50% passing size, and 1, an adjustable parameter. The correlation coefficient for all tests averages 0.999 for the cumulative distributions and 0.912 for the retained distributions. (Author) 15 refs.

  17. Effect of particle size on dc conductivity, activation energy and diffusion coefficient of lithium iron phosphate in Li-ion cells

    Directory of Open Access Journals (Sweden)

    T.V.S.L. Satyavani

    2016-03-01

    Full Text Available Cathode materials in nano size improve the performance of batteries due to the increased reaction rate and short diffusion lengths. Lithium Iron Phosphate (LiFePO4 is a promising cathode material for Li-ion batteries. However, it has its own limitations such as low conductivity and low diffusion coefficient which lead to high impedance due to which its application is restricted in batteries. In the present work, increase of conductivity with decreasing particle size of LiFePO4/C is studied. Also, the dependence of conductivity and activation energy for hopping of small polaron in LiFePO4/C on variation of particle size is investigated. The micro sized cathode material is ball milled for different durations to reduce the particle size to nano level. The material is characterized for its structure and particle size. The resistivities/dc conductivities of the pellets are measured using four probe technique at different temperatures, up to 150 °C. The activation energies corresponding to different particle sizes are calculated using Arrhenius equation. CR2032 cells are fabricated and electrochemical characteristics, namely, ac impedance and diffusion coefficients, are studied.

  18. Prenatal Exposure to Autism-Specific Maternal Autoantibodies Alters Proliferation of Cortical Neural Precursor Cells, Enlarges Brain, and Increases Neuronal Size in Adult Animals.

    Science.gov (United States)

    Martínez-Cerdeño, Verónica; Camacho, Jasmin; Fox, Elizabeth; Miller, Elaine; Ariza, Jeanelle; Kienzle, Devon; Plank, Kaela; Noctor, Stephen C; Van de Water, Judy

    2016-01-01

    Autism spectrum disorders (ASDs) affect up to 1 in 68 children. Autism-specific autoantibodies directed against fetal brain proteins have been found exclusively in a subpopulation of mothers whose children were diagnosed with ASD or maternal autoantibody-related autism. We tested the impact of autoantibodies on brain development in mice by transferring human antigen-specific IgG directly into the cerebral ventricles of embryonic mice during cortical neurogenesis. We show that autoantibodies recognize radial glial cells during development. We also show that prenatal exposure to autism-specific maternal autoantibodies increased stem cell proliferation in the subventricular zone (SVZ) of the embryonic neocortex, increased adult brain size and weight, and increased the size of adult cortical neurons. We propose that prenatal exposure to autism-specific maternal autoantibodies directly affects radial glial cell development and presents a viable pathologic mechanism for the maternal autoantibody-related prenatal ASD risk factor. PMID:25535268

  19. Modulation of mesenchymal stem cell behavior by nano- and micro-sized β-tricalcium phosphate particles in suspension and composite structures

    International Nuclear Information System (INIS)

    Interest has grown in the use of microparticles and nanoparticles for modifying the mechanical and biological properties of synthetic bone composite structures. Micro- and nano-sized calcium phosphates are of interest for their osteoinductive behavior. Engineered composites incorporating polymers and ceramics, such as poly-l-lactic acid (PLLA) and beta-tricalcium phosphate (β-TCP), for bone tissue regeneration have been well investigated for their proliferative and osteoinductive abilities. Only limited research has been done to investigate the effects of different sizes of β-TCP particles on human mesenchymal stromal cell behavior. As such, the aim of this study was to investigate the modulations of human adipose-derived stem cell (hASCs) behavior within cell/particle and cell/composite systems as functions of particle size, concentration, and exposure time. The incorporation of nanoscale calcium phosphate resulted in improved mechanical properties and osteogenic behavior within the scaffold compared to the microscale calcium phosphate additives. Particle exposure results indicate that cytotoxicity on hASCs correlates inversely with particle size and increases with the increasing exposure time and particle concentration. Composites with increasing β-TCP content, whether microparticles or nanoparticles, were less toxic than colloidal micro- and nano-sized β-TCP particles directly supplied to hASCs. The difference in viability observed as a result of varying exposure route is likely related to the increased cell–particle interactions in the direct exposure compared to the particles becoming trapped within the scaffold/polymer matrix

  20. Modulation of mesenchymal stem cell behavior by nano- and micro-sized β-tricalcium phosphate particles in suspension and composite structures

    Energy Technology Data Exchange (ETDEWEB)

    Smoak, Mollie; Hogan, Katie; Kriegh, Lisa; Chen, Cong, E-mail: cchen19@tigers.lsu.edu; Terrell, LeKeith B.; Qureshi, Ammar T.; Todd Monroe, W. [Louisiana State University and LSU AgCenter, Department of Biological and Agricultural Engineering (United States); Gimble, Jeffrey M., E-mail: Jeffrey.Gimble@pbrc.edu [Tulane University School of Medicine, Center for Stem Cell Research & Regenerative Medicine (United States); Hayes, Daniel J., E-mail: danielhayes@lsu.edu [Louisiana State University and LSU AgCenter, Department of Biological and Agricultural Engineering (United States)

    2015-04-15

    Interest has grown in the use of microparticles and nanoparticles for modifying the mechanical and biological properties of synthetic bone composite structures. Micro- and nano-sized calcium phosphates are of interest for their osteoinductive behavior. Engineered composites incorporating polymers and ceramics, such as poly-l-lactic acid (PLLA) and beta-tricalcium phosphate (β-TCP), for bone tissue regeneration have been well investigated for their proliferative and osteoinductive abilities. Only limited research has been done to investigate the effects of different sizes of β-TCP particles on human mesenchymal stromal cell behavior. As such, the aim of this study was to investigate the modulations of human adipose-derived stem cell (hASCs) behavior within cell/particle and cell/composite systems as functions of particle size, concentration, and exposure time. The incorporation of nanoscale calcium phosphate resulted in improved mechanical properties and osteogenic behavior within the scaffold compared to the microscale calcium phosphate additives. Particle exposure results indicate that cytotoxicity on hASCs correlates inversely with particle size and increases with the increasing exposure time and particle concentration. Composites with increasing β-TCP content, whether microparticles or nanoparticles, were less toxic than colloidal micro- and nano-sized β-TCP particles directly supplied to hASCs. The difference in viability observed as a result of varying exposure route is likely related to the increased cell–particle interactions in the direct exposure compared to the particles becoming trapped within the scaffold/polymer matrix.

  1. Anode regeneration following carbon depositions in an industrial-sized anode supported solid oxide fuel cell operating on synthetic diesel reformate

    Science.gov (United States)

    Subotić, Vanja; Schluckner, Christoph; Mathe, Jörg; Rechberger, Jürgen; Schroettner, Hartmuth; Hochenauer, Christoph

    2015-11-01

    Carbon deposition is a primary concern during operation of solid oxide fuel cells (SOFCs) fueled with carbon-containing fuels. It leads to cell degradation and thus reduces SOFC sustained operation and durability. This paper reports on an experimental investigation of carbon formation on the nickel/yttria-stabilized zirconia (Ni/YSZ) anode of an anode-supported SOFC and its regeneration. The cell was fueled with a synthetically produced diesel reformate to investigate and simulate the cell behavior under real operating conditions. For this purpose the cell was operated under load to determine the critical operating time. Rapid carbon generation, such as at open circuit voltage (OCV), can be prevented when the cell is under load. Carbon depositions were detected using scanning electron microscopy (SEM) and further analyzed by Raman spectroscopy. Industrial-size cells suitable for commercial applications were studied. This study proves the reversibility of carbon formation and the reproducibility of the regeneration process. It shows that carbon formations can be recognized and effectively, fully and cell-protecting regenerated. It indicates the excellent possibility of using SOFCs in the automotive industry as an auxiliary power unit (APU) or combined power-heat unit, operated with diesel reformate, without danger from cell degradation caused by carbon-containing fuels.

  2. Changes in the number and size of nucleoli of Chara vulgaris L. antheridial filament cells during the period preceding light-induced re-initiation of cell divisions following a mitodepressive effect of darkness

    Directory of Open Access Journals (Sweden)

    Maria Kwiatkowska

    2014-02-01

    Full Text Available The changes in number and size of nucleoli of Chara vulgaris antheridial filament cells were monitored with the use of Howell and Black's silver staining method. After a 3-day mitodepressive treatment with darkness the cells were exposed to light which reactivated mitotic activity after 18-20 hours. Eight-celled antheridial filaments were observed. In the period preceding light-induced re-initiation of mitoses a gradual reconstruction of the number and size of nucleoli characteristic of control, as well as their total area per nucleus appeared. The obtained results indicate that one of the important conditions for a cell to be able to divide is accumulation of nucleolus components characteristic of a given developmental stage and this controls nucleologenesis of the subsequent cell cycle.

  3. THE SIZE AND SURFACE COATING OF NANOSILVER DIFFERENTIALLY AFFECTS BIOLOGICAL ACTIVITY IN BLOOD BRAIN BARRIER (RBEC4) CELLS.

    Science.gov (United States)

    Linking the physical properties of nanoparticles with differences in their biological activity is critical for understanding their potential toxicity and mode of action. The influence of aggregate size, surface coating, and surface charge on nanosilver's (nanoAg) movement through...

  4. Biological impacts of TiO2 on human lung cell lines A549 and H1299: particle size distribution effects

    International Nuclear Information System (INIS)

    Increasing use of titanium dioxide (TiO2) nanoparticles in many commercial applications has led to emerging concerns regarding the safety and environmental impact of these materials. In this study, we have investigated the biological impact of nano-TiO2 (with particle primary size of 20 nm Aeroxide P25) on human lung cell lines in vitro and also the effect of particle size distribution on the particle uptake and apparent toxicity. The biological impact of nano-TiO2 is shown to be influenced by the concentration and particle size distribution of the TiO2 and the impact was shown to differ between the two cell lines (A549 and H1299) investigated herein. A549 cell line was shown to be relatively resistant to the total amount of TiO2 particles uptaken, as measured by cell viability and metabolic assays, while H1299 had a much higher capacity to ingest TiO2 particles and aggregates, with consequent evidence of impact at concentrations as low as 30–150 μg/mL TiO2. Evidence gathered from this study suggests that both viability and metabolic assays (measuring metabolic and mitochondrial activities and also cellular ATP level) should be carried out collectively to gain a true assessment of the impact of exposure to TiO2 particles.

  5. Fat cell size and adipokine expression in relation to gender, depot and metabolic risk factors in morbidly obese adolescents

    OpenAIRE

    Zhang, Yiying; Zitsman, Jeffrey L.; Hou, Jue; Fennoy, Ilene; Guo, Kaiying; Feinberg, Joshua; Leibel, Rudolph L

    2013-01-01

    Objective To understand the regulation of adipocyte size and adipokine expression in relation to gender, anatomic location, adiposity, and metabolic risk factors in adolescents with morbid obesity. Design and Methods Adipocyte size and adipokine expression in paired abdominal subcutaneous (SAT) and omental (VAT) surgical adipose tissues were related to gender, anatomic location, adiposity, and metabolic risk factors in a group of morbidly obese adolescents. Results Significant depot- and/or g...

  6. Calmodulin and the target size of the (Ca2+ + Mg2+)-ATPase of human red-cell ghosts.

    Science.gov (United States)

    Cavieres, J D

    1984-04-11

    An average target size of 251 kDa has been obtained for the (Ca2+ + Mg2+)-ATPase of calmodulin-depleted erythrocyte ghosts by radiation inactivation with 16 MeV electrons. This is close to twice the size of the purified calcium-pump polypeptide. When calmodulin was included during the ATPase assay, a component of about 1 MDa appeared in addition to the activated dimer. PMID:6142728

  7. Ammonia concentrations in different size classes of ovarian follicles of sheep (Ovis aries): Possible mechanisms of accumulation and its effect on oocyte and granulosa cell growth in vitro.

    Science.gov (United States)

    Nandi, S; Gupta, P S P; Mondal, S

    2016-03-01

    The present study investigated the concentrations and the mechanisms of accumulation of ammonia in different sizes of ovarian follicles and the effect of ammonia on oocyte and granulosa cell growth and functions in vitro with sheep (Ovis aries) as an animal model. The effects of cyclicity, seasonality, phases of the estrous cycle, and seasons (environmental) on ammonia concentrations in follicular fluid were also investigated. The effect of ammonia on in vitro development of oocytes (maturation rate, viability rate, cleavage rate, morulae/blastocysts yield) recovered from different sizes of follicles was examined at the levels of 0, 50, 100, 150, 250, 300, and 500 μM. Same concentrations of ammonia were examined on growth parameters (metabolic activity, viability, cell number increment, monolayer formation, apoptosis rate) and hormone (progesterone, estrogen) secretion activity of granulosa cells in vitro. Results suggested as the follicle size increased, ammonia concentrations decreased. The ammonia concentrations in ovine follicular fluid were found to be 261.5 ± 32.4, 157.7 ± 19.2, and 42.9 ± 8.3 μM, respectively, for small, medium, and large follicles. The corresponding ranges were 290 to 238 μM, 184 to 142 μM, and 70 to 22 μM. The differences were due to more accumulation of fluid, less metabolic activity of granulosa cells, and elevation of protein, potassium, and chloride as the follicle size increased. The seasonality and phases of the estrous cycle did not have any effect on ammonia level in ovarian follicles. Ammonia concentrations in all size classes of follicles examined were significantly reduced in ewes during hot seasons compared to cold seasons and in acyclic animals compared to cyclic ones. Ammonia impaired oocyte development at 300 μM when the oocytes were isolated from small follicles and at 250 μM when the oocytes were isolated from medium and large follicles. In contrast, ammonia caused the negative impact on granulosa cells growth

  8. A Cell-Targeted, Size-Photocontrollable, Nuclear-Uptake Nanodrug Delivery System for Drug-Resistant Cancer Therapy

    OpenAIRE

    Qiu, Liping; Chen, Tao; Öçsoy, Ismail; Yasun, Emir; Wu, Cuichen; Zhu, Guizhi; You, Mingxu; Han, Da; Jiang, Jianhui; Yu, Ruqin; Tan, Weihong

    2014-01-01

    The development of multidrug resistance (MDR) has become an increasingly serious problem in cancer therapy. The cell-membrane overexpression of P-glycoprotein (P-gp), which can actively efflux various anticancer drugs from the cell, is a major mechanism of MDR. Nuclear-uptake nanodrug delivery systems, which enable intranuclear release of anticancer drugs, are expected to address this challenge by bypassing P-gp. However, before entering the nucleus, the nanocarrier must pass through the cell...

  9. Soy Biodiesel and Petrodiesel Emissions Differ in Size, Chemical Composition and Stimulation of Inflammatory Responses in Cells and Animals

    OpenAIRE

    Fukagawa, Naomi K.; Li, Muyao; Poynter, Matthew E; Palmer, Brian C.; Parker, Erin; Kasumba, John; Holmén, Britt A.

    2013-01-01

    Debate about the biological effects of biodiesel exhaust emissions exists due to variation in methods of exhaust generation and biological models used to assess responses. Because studies in cells do not necessarily reflect the integrated response of a whole animal, experiments were conducted in two human cell lines representing bronchial epithelial cells and macrophages and female mice using identical particle suspensions of raw exhaust generated by a Volkswagen light-duty diesel engine usin...

  10. Comparison of Ground Water Bacterial Cell Sizes from the Agricultural,Domestic and Industrial Areas of Mysore District,Karnataka State,India

    Institute of Scientific and Technical Information of China (English)

    Wadie Ahmed Mokbel; Sadanand M Yamakanamardi

    2008-01-01

    A two-year study on temporal variations in the ground water heterotrophic bacterial cell sizes of free living bacteria(FLB)and particle bound bacteria(PBB)from the agricultural,domestic and industrial areas was carried out from Februar y2005 to January 2007.The overall mean cell length of FLB and PBB was similar in all the ground water studied.However,the season wise grouped data revealed significant seasonal changes in cell length of FLB and PBB,as smaller bacteria were noticed during rainy season in the ground water in agricultural area in both the years,and only in the second year of study in domestic and industrial areas.Generally,it was noticed that there were summer maximum and rainy minimum values of the cell length of PBB in the ground water in agricultural,domestic and industrial areas in the second year of study.The Pearson's correlations showed the presence of 8(in agricultural area),5(in domestic)and 3(in industrial) significant correlations with environmental(Physico-chemical)parameters,respectively.The regression analysis revealed that as much as 12%of variation in the mean length of FL Bwas due to NO3(+)in agricultural area and 9%due to total solids(+)indomestic area.However,the 8% variation in bacterial cell size of FLB was due to Mg(+)in industrial area.Whereas,13%variation in mean length of PBB was due to S04(+)in agncultural area and 10%due to total anions of strong acid(TASA)(+)in domestic area.Furthermore,10% of variation Was due to PO4(+)in industrial area.Thus,the statistical analysis revealed that several environmental variables were potentially responsible for some of the temporal variations in aquatic heterotrophic bacterial cell size,suggesting probably the stressed environment in these ecosystems.

  11. Repair of rat critical size calvarial defect using osteoblast-like and umbilical vein endothelial cells seeded in gelatin/hydroxyapatite scaffolds.

    Science.gov (United States)

    Johari, Behrooz; Ahmadzadehzarajabad, Maryam; Azami, Mahmoud; Kazemi, Mansure; Soleimani, Mansooreh; Kargozar, Saied; Hajighasemlou, Saieh; Farajollahi, Mohammad M; Samadikuchaksaraei, Ali

    2016-07-01

    The present study used a previously developed three-dimensional Gelatin/Hydroxyapatite (Gel/HA) homogeneous nanocomposite scaffold with porosity of 82% and interconnecting pores ranging from 300 to 500 μm. Cell-seeded scaffolds were used to evaluate bone regeneration of rat critical-size calvarial defect. Totally, 36 male Wistar rats were randomly divided into four experimental groups, including blank defect (defects without any graft), blank scaffold (defects filled with Gel/HA scaffold without cells), and two groups of cell-seeded scaffolds (defects filled with either Gel/HA scaffold seeded with osteoblast-like and endothelial cells or osteoblast-like cell-seeded constructs). After 1, 4, and 12 weeks of scaffold implantation, rats were sacrificed and the calvaria were harvested for histological, immunohistochemical and histomorphometric analysis. In vitro tests showed that scaffolds were nontoxic to cells and promoted ideal cellular attachment. In vivo investigation on scaffold revealed that blank calvarial defects indicated incomplete tissue coverage and little evidence of bone healing. However, blank scaffold and cell-seeded scaffolds significantly promoted osteoconduction and ostegogenesis. Taken together, pre-seeded Gel/HA nanocomposite scaffold with osteoblasts and endothelial cells presented an effective combination to improve osteogenesis in the engineered bone implant. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1770-1778, 2016. PMID:26990815

  12. The impact of different nanoparticle surface chemistry and size on uptake and toxicity in a murine macrophage cell line

    International Nuclear Information System (INIS)

    This study investigated the uptake, kinetics and cellular distribution of different surface coated quantum dots (QDs) before relating this to their toxicity. J774.A1 cells were treated with organic, COOH and NH2 (PEG) surface coated QDs (40 nM). Model 20 nm and 200 nm COOH-modified coated polystyrene beads (PBs) were also examined (50 μg ml-1). The potential for uptake of QDs was examined by both fixed and live cell confocal microscopy as well as by flow cytometry over 2 h. Both the COOH 20 nm and 200 nm PBs were clearly and rapidly taken up by the J774.A1 cells, with uptake of 20 nm PBs being relatively quicker and more extensive. Similarly, COOH QDs were clearly taken up by the macrophages. Uptake of NH2 (PEG) QDs was not detectable by live cell imaging however, was observed following 3D reconstruction of fixed cells, as well as by flow cytometry. Cells treated with organic QDs, monitored by live cell imaging, showed only a small amount of uptake in a relatively small number of cells. This uptake was insufficient to be detected by flow cytometry. Imaging of fixed cells was not possible due to a loss in cell integrity related to cytotoxicity. A significant reduction (p 2 (PEG) QDs, 20 nm and 200 nm PBs at pH 4.0 (indicative of an endosome) after 2 h, suggesting reduced stability. No evidence of exocytosis was found over 2 h. These findings confirm that surface coating has a significant influence on the mode of NP interaction with cells, as well as the subsequent consequences of that interaction

  13. {sup 99m}Tc-MIBI scintigraphy of parathyroid adenomas and its relation to tumour size and oxyphil cell abundance

    Energy Technology Data Exchange (ETDEWEB)

    Melloul, M.; Paz, A.; Cytron, S. [Dept. of Nuclear Medicine, Hasharon Hospital, Rabin Medical Center, Petah Tikva (Israel); Koren, R.; Gal, R. [Dept. of Pathology, Hasharon Hospital, Rabin Medical Center, Petah Tikva (Israel); Feinmesser, R. [Dept. of Oto-Rhino-Laryngology, Hasharon Hospital, Rabin Medical Center, Petah Tikva (Israel)

    2001-02-01

    The aim of this study was to assess the correlation between technetium-99m methoxyisobutylisonitrile (MIBI) uptake by parathyroid adenomas, oxyphil cell content and volume of the lesions. Thirty-one patients with parathyroid adenomas were evaluated prospectively. Preoperative double-phase {sup 99m}Tc-MIBI scintigraphy was performed in all patients and tracer uptake by parathyroid lesions was assessed semi-quantitatively employing region of interest ratios to normal adjacent neck areas. Surgical specimens underwent histological evaluation and oxyphil cell content was determined. The intensity of tracer uptake was compared with oxyphil cell content, volume of the lesions and serum levels of calcium and parathormone. {sup 99m}Tc-MIBI tracer uptake was correlated with oxyphil cell content, volume of parathyroid lesions and the functional status of the parathyroid adenomas. Tracer accumulation in oxyphil cells might partially explain the preferential {sup 99m}Tc-MIBI retention in parathyroid lesions. (orig.)

  14. 99mTc-MIBI scintigraphy of parathyroid adenomas and its relation to tumour size and oxyphil cell abundance

    International Nuclear Information System (INIS)

    The aim of this study was to assess the correlation between technetium-99m methoxyisobutylisonitrile (MIBI) uptake by parathyroid adenomas, oxyphil cell content and volume of the lesions. Thirty-one patients with parathyroid adenomas were evaluated prospectively. Preoperative double-phase 99mTc-MIBI scintigraphy was performed in all patients and tracer uptake by parathyroid lesions was assessed semi-quantitatively employing region of interest ratios to normal adjacent neck areas. Surgical specimens underwent histological evaluation and oxyphil cell content was determined. The intensity of tracer uptake was compared with oxyphil cell content, volume of the lesions and serum levels of calcium and parathormone. 99mTc-MIBI tracer uptake was correlated with oxyphil cell content, volume of parathyroid lesions and the functional status of the parathyroid adenomas. Tracer accumulation in oxyphil cells might partially explain the preferential 99mTc-MIBI retention in parathyroid lesions. (orig.)

  15. Effects of pore size gradient in the substrate of a gas diffusion layer on the performance of a proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Highlights: • The dual layered substrate with different carbon fibers formed a pore size gradient. • The gradient increased the cell performances under various humidity conditions. • The water management was improved by balancing the capillary pressure gradient. - Abstract: The proton exchange membrane fuel cell (PEMFC) is one of the up-and-coming power sources for automotive vehicles. To generate a stable performance during driving, the PEMFC needs to achieve an optimized water management under various humidity conditions. Being the path for the two-phase flow of fuel, air, and water, the gas diffusion layer (GDL) is a critical component, which influences water balance. In this study, a pore size gradient structure is introduced in the substrate of a GDL to control the local capillary pressure gradient, which is the driving force of the water flux inside the PEMFC. Through measurements of steady-state performance, transient response, voltage instability and electrochemical impedance spectroscopy, it was found that the pore size gradient structure improves the cell performance regardless of the relative humidity conditions used (50% and 100%). Furthermore, it is possible to hold the water on the membrane for higher ion conductivity and drain it toward the channel to secure gas supply toward the catalyst layer. In addition, it was also confirmed that the structural change enhances the bending stiffness of the GDL

  16. The influence of particle size and static magnetic fields on the uptake of magnetic nanoparticles into three dimensional cell-seeded collagen gel cultures.

    Science.gov (United States)

    Lewis, Emily E L; Child, Hannah W; Hursthouse, Andrew; Stirling, David; McCully, Mark; Paterson, David; Mullin, Margaret; Berry, Catherine C

    2015-08-01

    Over recent decades there has been and continues to be major advances in the imaging, diagnosis and potential treatment of medical conditions, by the use of magnetic nanoparticles. However, to date the majority of cell delivery studies employ a traditional 2D monolayer culture. This article aims to determine the ability of various sized magnetic nanoparticles to penetrate and travel through a cell seeded collagen gel model, in the presence or absence of a magnetic field. Three different sized (100, 200, and 500 nm) nanoparticles were employed in the study. The results showed cell viability was unaffected by the presence of nanoparticles over a 24-h test period. The initial uptake of the 100 nm nanoparticle into the collagen gel structure was superior compared to the larger sized nanoparticles under the influence of a magnetic field and incubated for 24 h. Interestingly, it was the 200 nm nanoparticles, which proved to penetrate the gel furthest, under the influence of a magnetic field, during the initial culture stage after 1-h incubation. PMID:25358626

  17. A disposable, roll-to-roll hot-embossed inertial microfluidic device for size-based sorting of microbeads and cells.

    Science.gov (United States)

    Wang, Xiao; Liedert, Christina; Liedert, Ralph; Papautsky, Ian

    2016-05-21

    Inertial microfluidics has been a highly active area of research in recent years for high-throughput focusing and sorting of synthetic and biological microparticles. However, existing inertial microfluidic devices always rely on microchannels with high-aspect-ratio geometries (channel width w h) to achieve size-based sorting of microparticles and cells. The simple LAR geometry of the device enables successful high-throughput fabrication using R2R hot embossing. With optimized flow conditions and channel dimensions, we demonstrate continuous sorting of a mixture of 15 μm and 10 μm diameter microbeads with >97% sorting efficiency using the low-cost and disposable R2R chip. We further demonstrate size-based sorting of bovine white blood cells, demonstrating the ability to process real cellular samples in our R2R chip. We envision that this R2R hot-embossed inertial microfluidic chip will serve as a powerful yet low-cost and disposable tool for size-based sorting of synthetic microparticles in industrial applications or cellular samples in cell biology research and clinical diagnostics. PMID:27050341

  18. Exposure to silver nanoparticles induces size- and dose-dependent oxidative stress and cytotoxicity in human colon carcinoma cells

    DEFF Research Database (Denmark)

    Miethling-Graff, Rona; Rumpker, Rita; Richter, Madeleine;

    2014-01-01

    The antimicrobial properties of silver nanoparticles (AgNPs) have made these particles one of the most frequently utilized nanomaterials in consumer products; therefore, a comprehensive understanding of their toxicity is necessary. In particular, information about the cellular uptake and size...

  19. The effect of pupil size on stimulation of the melanopsin containing retinal ganglion cells, as evaluated by monochromatic pupillometry

    DEFF Research Database (Denmark)

    Nissen, Claus Jeppe; Sander, Birgit; Lund-Andersen, Henrik

    2012-01-01

    Purpose: To evaluate the influence of the size of the light exposed pupil in one eye on the pupillary light reflex of the other eye. Method: Using a monochromatic pupillometer, the left eye in each of 10 healthy subjects was exposed to 20¿s of monochromatic light of luminance 300¿cd/m(2), first r...

  20. Catalytic activity vs. size correlation in platinum catalysts of PEM fuel cells prepared on carbon black by different methods

    Energy Technology Data Exchange (ETDEWEB)

    Nores-Pondal, F.J.; Granada, M.; Corti, H.R. [Departamento de Fisica de la Materia Condensada, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica (CNEA), General Paz 1499, 1650 San Martin, Buenos Aires (Argentina); Vilella, I.M.J.; de Miguel, S.R.; Scelza, O.A. [Instituto de Investigaciones en Catalisis y Petroquimica (INCAPE), Facultad de Ingenieria Quimica (Universidad Nacional del Litoral) - CONICET, Santiago del Estero 2654, 3000 Santa Fe (Argentina); Troiani, H. [Departamento de Fisica, Centro Atomico Bariloche, Comision Nacional de Energia Atomica (CNEA), Av. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina)

    2009-10-15

    In this work nanoparticulated platinum catalysts have been prepared on carbon Vulcan XC-72 using three methods starting with chloroplatinic acid as a precursor: (i) formic acid as a reductor agent; (ii) impregnation method followed by reduction in hydrogen atmosphere at moderated temperature; and (iii) microwave-assisted reduction in ethylene glycol. The catalytic and size studies were also performed on a commercial Pt catalyst (E-Tek, De Nora). The characterization of the particle size and distribution was performed by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). The characterizations of the catalytic and electrocatalytic properties of the catalysts were determined by studying the cyclohexane dehydrogenation reaction (CHD) and the behavior under cyclic voltammetry (CV) in sulfuric acid solutions. The measured electrochemical activity, along with the hydrogen chemisorption of the catalysts allows the estimation of effective particle sizes, which are much larger than those measured by TEM and XRD. The catalysts prepared by reduction with formic acid and ethylene glycol (microwave-assisted) show electrochemical activities very close to those of the commercial catalyst, and are almost insensitive to the Pt dispersion or Pt particle size. The chemical activity in CHD correlates well with the metallic dispersion determined by hydrogen chemisorption, indicating similar accesibility of H{sub 2} and cyclohexane to the catalyst surface. (author)

  1. Theoretical insights into highly transparent multi-sized conducting films with high-haze and wide-angular scattering for thin film solar cells

    Science.gov (United States)

    Bai, Lisha; Liu, Bofei; Chen, Ze; Huang, Qian; Li, Baozhang; Zhang, Dekun; Sun, Jian; Wei, Changchun; Zhao, Ying; Zhang, Xiaodan

    2015-11-01

    Recent advances in light trapping schemes open up new gateways for enhancing the absorption of solar energy that approaches and overcomes the Yablonovitch 4n2 limit based on isotropic Lambertian scatterers. Achieving wide-angular scattering while maintaining a strong scattering intensity is the key to realize a Lambertian-like scatterer that may have a great potential to approach the absorption upper limit. However, few current light trapping strategies can experimentally extend the scattering angular domains in absorbers while maintaining a high scattering intensity. In this paper, we theoretically and experimentally investigate multi-sized transparent conducting oxide (TCO) films, which are comprised of micro-sized, magnetron-sputtered and chemically etched aluminum-doped zinc oxide (ZnO:Al), coated with metal organic chemical vapor deposition (MOCVD) deposited nano-sized, boron-doped zinc oxide (ZnO:B) pyramids. We demonstrate that the multi-sized TCOs in this study can efficiently increase the total transmittance in the visible spectral range, enhance the scattering intensity, successfully extend the scattering angular domains to 90°, and improve the short-circuit current density and power output of solar cells. The combination of these factors endows the TCOs with the significant potential for realizing a Lambertian-like scatterer. Accordingly, the multi-sized architecture may inspire fresh ideas for realizing more innovative light-trapping architectures.

  2. Cell size and fat content of dietary-restricted Caenorhabditis elegans are regulated by ATX-2, an mTOR repressor.

    Science.gov (United States)

    Bar, Daniel Z; Charar, Chayki; Dorfman, Jehudith; Yadid, Tam; Tafforeau, Lionel; Lafontaine, Denis L J; Gruenbaum, Yosef

    2016-08-01

    Dietary restriction (DR) is a metabolic intervention that extends the lifespan of multiple species, including yeast, flies, nematodes, rodents, and, arguably, rhesus monkeys and humans. Hallmarks of lifelong DR are reductions in body size, fecundity, and fat accumulation, as well as slower development. We have identified atx-2, the Caenorhabditis elegans homolog of the human ATXN2L and ATXN2 genes, as the regulator of these multiple DR phenotypes. Down-regulation of atx-2 increases the body size, cell size, and fat content of dietary-restricted animals and speeds animal development, whereas overexpression of atx-2 is sufficient to reduce the body size and brood size of wild-type animals. atx-2 regulates the mechanistic target of rapamycin (mTOR) pathway, downstream of AMP-activated protein kinase (AMPK) and upstream of ribosomal protein S6 kinase and mTOR complex 1 (TORC1), by its direct association with Rab GDP dissociation inhibitor β, which likely regulates RHEB shuttling between GDP-bound and GTP-bound forms. Taken together, this work identifies a previously unknown mechanism regulating multiple aspects of DR, as well as unknown regulators of the mTOR pathway. They also extend our understanding of diet-dependent growth retardation, and offers a potential mechanism to treat obesity. PMID:27457958

  3. A new mechanism for the regulation of stomatal aperture size in intact leaves: accumulation of mesophyll-derived sucrose in the guard-cell wall of Vicia faba

    International Nuclear Information System (INIS)

    At various times after pulse-labeling broad bean (Vicia faba L.) leaflets with 14CO2, whole-leaf pieces and rinsed epidermal peels were harvested and subsequently processed for histochemical analysis. Cells dissected from whole leaf retained apoplastic contents, whereas those from rinsed peels contained only symplastic contents. Sucrose (Suc)-specific radioactivity peaked (111 GBq mol-1) in palisade cells at 20 min. In contrast, the 14C content and Suc-specific radioactivity were very low in guard cells for 20 min, implying little CO2 incorporation; both then peaked at 40 min. The guard-cell apoplast had a high maximum Suc-specific radioactivity (204 GBq mol-1) and a high Suc influx rate (0.05 pmol stoma-1 min-1). These and other comparisons implied the presence of (a) multiple Suc pools in mesophyll cells, (b) a localized mesophyll-apoplast region that exchanges with phloem and stomata, and (c) mesophyll-derived Suc in guard-cell walls sufficient to diminish stomatal opening by approximately 3 micrometers. Factors expected to enhance Suc accumulation in guard-cell walls are (a) high transpiration rate, which closes stomata, and (b) high apoplastic Suc concentration, which is elevated when mesophyll Suc efflux exceeds translocation. Therefore, multiple physiological factors are integrated in the attenuation of stomatal aperture size by this previously unrecognized mechanism

  4. Dental pulp-derived stromal cells exhibit a higher osteogenic potency than bone marrow-derived stromal cells in vitro and in a porcine critical-size bone defect model

    OpenAIRE

    Jensen Jonas; Tvedesøe Claus; Rölfing Jan Hendrik Duedal; Foldager Casper Bindzus; Lysdahl Helle; Kraft David Christian Evar; Chen Muwan; Baas Jorgen; Le Dang Quang Svend; Bünger Cody Eric

    2016-01-01

    Introduction: The osteogenic differentiation of bone marrow-derived mesenchymal stromal cells (BMSCs) was compared with that of dental pulp-derived stromal cells (DPSCs) in vitro and in a pig calvaria critical-size bone defect model. Methods: BMSCs and DPSCs were extracted from the tibia bone marrow and the molar teeth of each pig, respectively. BMSCs and DPSCs were cultured in monolayer and on a three-dimensional (3D) polycaprolactone (PCL) – hyaluronic acid – tricalcium phos...

  5. Electrochemical construction of a bio-inspired micro/nano-textured structure with cell-sized microhole arrays on biomedical titanium to enhance bioactivity

    International Nuclear Information System (INIS)

    Highlights: • The bio-inspired structure mimicked mulit-level structures of natural bone. • Ordered cell-sized microhole arrays were employed as microscale structure. • High surface roughness and superhydrophilicity were achieved on the titanium surface. • The bio-inspired titanium surface showed superior ability of biomineralization. • Cell responses were enhanced on the bio-inspired micro/nano-texutred surface. - Abstract: Biomimetic surface design of medical implants is vitally crucial to improve cellular responses and the integration of tissue onto materials. In this study, a novel hierarchical cell-sized microhole array combined with a nano-network structure was fabricated on a medical titanium surface to mimic multi-level bone structure. A three-step procedure was developed as follows: 1) electrochemical self-organization of etching on titanium substrate to create highly ordered cell-sized microhole arrays, 2) suitable dual acid etching to increase the roughness of the microholes, and then 3) electrochemical anodization in a NaOH electrolyte to construct a nano-network porous titania layer on the above micro-roughened surface. The bio-inspired micro/nano-textured structure presented the enhanced wettability and superhydrophilicity. The ability of in vitro biomineralization and corrosion resistance of the bio-inspired micro/nano-textured structure were enhanced after annealing treatment. More importantly, the bio-inspired micro/nano-textured structure on the titanium surface possessed a favourable interfacial environment to enhance attachment and proliferation of human osteoblast-like MG63 cells. All of the results demonstrated that such a bio-inspired surface of micro/nano-textured porous TiO2 is a most promising candidate for the next generation of titanium implants

  6. Isolation, detection, and immunomorphological characterization of circulating tumor cells (CTCs from patients with different types of sarcoma using isolation by size of tumor cells: a window on sarcoma-cell invasion

    Directory of Open Access Journals (Sweden)

    Chinen LTD

    2014-09-01

    Full Text Available Ludmilla T Domingos Chinen,1 Celso A Lopes Mello,2 Emne Ali Abdallah,1 Luciana MM Ocea,1 Marcilei E Buim,1 Natália M Breve,1 José Luiz Gasparini Junior,1 Marcello F Fanelli,2 Patrizia Paterlini-Bréchot3 1International Research Center, 2Department of Clinical Oncology, AC Camargo Cancer Center, São Paulo, Brazil; 3Unité INSERM U807, Université Paris Descartes, Paris, France Background: Sarcomas are rare and heterogeneous neoplasms with poor prognosis that are thought to spread to distant organs mainly by hematogenous dissemination. However, circulating tumor cells (CTCs have never been visualized in sarcomas. Objectives: To investigate the feasibility of using isolation by size of tumor cells (ISET for isolation, identification, and characterization of CTCs derived from patients with high-grade and metastatic sarcomas. Patients and methods: We studied eleven patients with metastatic/recurrent or locally advanced soft-tissue sarcomas (STSs, six of whom had synovial sarcomas. Blood samples (8 mL were collected from patients with advanced STS and treated by ISET, a marker- independent approach that isolates intact CTCs from blood, based on their larger size compared with leukocytes. CTCs were identified by cytomorphology and characterized by dual-color immunocytochemistry using antivimentin or anti-Pan CK, and anti-CD45. Results: All patients with STS included in this study showed CTCs, with numbers ranging from two to 48 per 8 mL of blood. Conclusion: This study shows the feasibility of isolating, identifying, and characterizing CTCs from patients with different types of sarcomas and the presence of circulating sarcoma cells in all the tested patients. Our results set the basis for further studies aimed at exploring the presence, number, and immunomolecular characteristics of CTCs in different types of sarcoma, and bring more light to the mechanisms of tumor invasion for these tumors. Keywords: sarcoma, circulating tumor cells, ISET 

  7. In vitro cytotoxicity of SiO2 or ZnO nanoparticles with different sizes and surface charges on U373MG human glioblastoma cells

    Directory of Open Access Journals (Sweden)

    Kim JE

    2014-12-01

    Full Text Available Jung-Eun Kim,1,* Hyejin Kim,1,* Seong Soo A An,2 Eun Ho Maeng,3 Meyoung-Kon Kim,4 Yoon-Jae Song1 1Department of Life Science, 2Department of Bionano Technology, Gachon University, Seongnam-Si, South Korea; 3Korea Testing and Research Institute, Seoul, South Korea; 4Department of Biochemistry and Molecular Biology, Korea University Medical School and College, Seoul, South Korea *These authors contributed equally to this work Abstract: Silicon dioxide (SiO2 and zinc oxide (ZnO nanoparticles are widely used in various applications, raising issues regarding the possible adverse effects of these metal oxide nanoparticles on human cells. In this study, we determined the cytotoxic effects of differently charged SiO2 and ZnO nanoparticles, with mean sizes of either 100 or 20 nm, on the U373MG human glioblastoma cell line. The overall cytotoxicity of ZnO nanoparticles against U373MG cells was significantly higher than that of SiO2 nanoparticles. Neither the size nor the surface charge of the ZnO nanoparticles affected their cytotoxicity against U373MG cells. The 20 nm SiO2 nanoparticles were more toxic than the 100 nm nanoparticles against U373MG cells, but the surface charge had little or no effect on their cytotoxicity. Both SiO2 and ZnO nanoparticles activated caspase-3 and induced DNA fragmentation in U373MG cells, suggesting the induction of apoptosis. Thus, SiO2 and ZnO nanoparticles appear to exert cytotoxic effects against U373MG cells, possibly via apoptosis. Keyword: apoptosis

  8. Degradation mechanisms of Platinum Nanoparticle Catalysts in Proton Exchange Membrane Fuel Cells: The Role of Particle Size

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Kang; Groom, Daniel J.; Wang, Xiaoping; Yang, Zhiwei; Gummalla, Mallika; Ball, Sarah C.; Myers, Deborah J.; Ferreira, Paulo J.

    2014-10-14

    Five membrane-electrode assemblies (MEAs) with different average sizes of platinum (Pt) nanoparticles (2.2, 3.5, 5.0, 6.7, and 11.3 nm) in the cathode were analyzed before and after potential cycling (0.6 to 1.0 V, 50 mV/s) by transmission electron microscopy. Cathodes loaded with 2.2 nm and 3.5 nm catalyst nanoparticles exhibit the following changes during electrochemical cycling: (i) substantial broadening of the size distribution relative to the initial size distribution, (ii) presence of coalesced particles within the electrode, and (iii) precipitation of sub-micron-sized particles with complex shapes within the membrane. In contrast, cathodes loaded with 5.0 nm, 6.7 nm and 11.3 nm size catalyst nanoparticles are significantly less prone to the aforementioned effects. As a result, the electrochemically-active surface area (ECA) of MEA cathodes loaded with 2.2 nm and 3.5 nm nanoparticle catalysts degrades dramatically within 1,000 cycles of operation, while the electrochemically-active surface area of MEA cathodes loaded with 5.0 nm, 6.7 nm and 11.3 nm nanoparticle catalysts appears to be stable even after 10,000 cycles. The loss in MEA performance for cathodes loaded with 2.2 nm and 3.5 nm nanoparticle catalysts appears to be due to the loss in electrochemically-active surface area concomitant with the observed morphological changes in these nanoparticle catalysts

  9. Development and application of resistive pulse spectroscopy: studies on the size, form and deformability of red blood cells

    Energy Technology Data Exchange (ETDEWEB)

    Yee, J.P.

    1979-01-01

    The following studies were conducted using the resistive pulse spectroscopy (RPS) technique: cumulative spectra and individual pulse forms for rigid latex polymer spheres; acquisition and analysis of RPS spectral data by means of special computer program; interaction of red blood cells with glutaraldehyde; membrane properties of erythrocytes undergoing abrupt osmotic hemolysis; reversible effects of the binding of chlorpromazine HCl at the red cell membrane surface; effects of high cholesterol diet on erythrocytes of guinea pigs; and multi-population analysis for a mixture of fetal and maternal red cells. (HLW)

  10. Comparison of Cell Viability and Embryoid Body Size of Two Embryonic Stem Cell Lines After Different Exposure Times to Bone Morphogenetic Protein 4

    OpenAIRE

    Nehleh Zarei Fard; Tahereh Talaei-Khozani; Soghra Bahmanpour; Tahereh Esmaeilpour

    2015-01-01

    Background: Activation of bone morphogenetic protein 4 (BMP4) signaling pathway in embryonic stem (ES) cells plays an important role in controlling cell proliferation, differentiation, and apoptosis. Adverse effects of BMP4 occur in a time dependent manner; however, little is known about the effect of different time exposure of this growth factor on cell number in culture media. In this study, we investigated the role of two different exposure times to BMP4 in cell viability, embryoid body (E...

  11. The effects of ultraviolet light on host cell reactivation and plaque size of Herpes simplex virus type 1 in C3H/10T1/2 mouse cells

    International Nuclear Information System (INIS)

    Herpes simplex virus-type 1 (HSV-1) plaque-forming ability and plaque size were measured on (C3H/10T1/2) cell monolayers as functions of pretreatment dose with UV light at different times before inoculation with virus, in order to determine if UV-enhanced reactivation (ER) of UV-irradiated virus, as well as associated phenomena, could be obtained in this cell system. The number of virus plaques observed (i.e. the capacity of the cells to support virus growth) and the size of the plaques were found to increase substantially with pretreatment of the cells with UV light. However, no significant ER was observed. Therefore, the mechanisms responsible for the increases in plaque size and cell capacity seem to be independent of those responsible for ER. In work by others, C3H/10T1/2 cells have been transformed by UV light at doses similar to those used in this study; the absence of ER of UV-irradiated virus in this study indicates that the mechanism underlying ER is not required for transformation. (author)

  12. Thymic regulatory T cell niche size is dictated by limiting interleukin 2 from antigen-bearing dendritic cells and feedback competition

    OpenAIRE

    Weist, Brian M.; Kurd, Nadia; Boussier, Jeremy; Chan, Shiao Wei; Robey, Ellen A.

    2015-01-01

    Thymic regulatory T (Treg) cell production requires interleukin 2 (IL-2) and agonist TCR ligands, and is controlled by competition for a limited developmental niche, but the thymic sources of IL-2 and the factors that limit access to the niche are poorly understood. Here we show that IL-2 produced by antigen-bearing dendritic cells plays a key role in Treg cell development, and that existing Treg cells limit new Treg cell development by competing for IL-2. . Our data suggest that antigen-pres...

  13. Effect of the alkaline cation size on the conductivity in gel polymer electrolytes and their influence on photo electrochemical solar cells.

    Science.gov (United States)

    Bandara, T M W J; Fernando, H D N S; Furlani, M; Albinsson, I; Dissanayake, M A K L; Ratnasekera, J L; Mellander, B-E

    2016-04-20

    The nature and concentration of cationic species in the electrolyte exert a profound influence on the efficiency of nanocrystalline dye-sensitized solar cells (DSSCs). A series of DSSCs based on gel electrolytes containing five alkali iodide salts (LiI, NaI, KI, RbI and CsI) and polyacrylonitrile with plasticizers were fabricated and studied, in order to investigate the dependence of solar cell performance on the cation size. The ionic conductivity of electrolytes with relatively large cations, K(+), Rb(+) and Cs(+), was higher and essentially constant, while for the electrolytes containing the two smaller cations, Na(+) and Li(+), the conductivity values were lower. The temperature dependence of conductivity in this series appears to follow the Vogel-Tamman-Fulcher equation. The sample containing the smallest cation shows the lowest conductivity and the highest activation energy of ∼36.5 meV, while K(+), Rb(+) and Cs(+) containing samples show an activation energy of ∼30.5 meV. DSSCs based on the gel electrolyte and a TiO2 double layer with the N719 dye exhibited an enhancement in the open circuit voltage with increasing cation size. This can be attributed to the decrease in the recombination rate of electrons and to the conduction band shift resulting from cation adsorption by TiO2. The maximum efficiency value, 3.48%, was obtained for the CsI containing cell. The efficiencies shown in this study are lower compared to values reported in the literature, and this can be attributed to the use of a single salt and the absence of other additives, since the focus of the present study was to analyze the cation effect. The highest short circuit current density of 9.43 mA cm(-2) was shown by the RbI containing cell. The enhancement of the solar cell performance with increasing size of the cation is discussed in terms of the effect of the cations on the TiO2 anode and ion transport in the electrolyte. In liquid electrolyte based DSSCs, the short circuit current density

  14. mRNA concentrations of MIF in subcutaneous abdominal adipose cells are associated with adipocyte size and insulin action

    OpenAIRE

    Koska, Juraj; Stefan, Norbert; Dubois, Severine; Trinidad, Cathy; Considine, Robert V; Funahashi, Tohru; Bunt, Joy C.; Ravussin, Eric; Permana, Paska A.

    2009-01-01

    Objective To determine whether the mRNA concentrations of inflammation response genes in isolated adipocytes and in cultured preadipocytes are related to adipocyte size and in vivo insulin action in obese individuals. Design Cross-sectional inpatient study. Subjects Obese Pima Indians with normal glucose tolerance. Measurements Adipocyte diameter (by microscope technique; n=29), expression of candidate genes (by quantitative real-time PCR) in freshly isolated adipocytes (monocyte chemoattract...

  15. Experimental study on size effect in quasi-static compressive behavior of closed-cell aluminium foams

    Czech Academy of Sciences Publication Activity Database

    Koudelka_ml., Petr; Zlámal, Petr; Kytýř, Daniel; Fíla, Tomáš; Jiroušek, Ondřej

    Prague: Czech Technical University in Prague, Faculty of Transportation Sciences, 2012 - (Jiroušek, O.; Kytýř, D.), s. 115-118 ISBN 978-80-01-05062-0. [Bilateral Czech/German Symposium /13./. Telč (CZ), 05.06.2012-08.06.2012] Grant ostatní: GA ČR(CZ) GAP105/12/0824 Institutional support: RVO:68378297 Keywords : metal foam * compressive behaviour * size effect Subject RIV: JI - Composite Materials

  16. Regional and cell-type-specific effects of DAMGO on striatal D1 and D2 dopamine receptor-expressing medium-sized spiny neurons

    Directory of Open Access Journals (Sweden)

    Christopher J Evans

    2012-03-01

    Full Text Available The striatum can be divided into the DLS (dorsolateral striatum and the VMS (ventromedial striatum, which includes NAcC (nucleus accumbens core and NAcS (nucleus accumbens shell. Here, we examined differences in electrophysiological properties of MSSNs (medium-sized spiny neurons based on their location, expression of DA (dopamine D1/D2 receptors and responses to the μ-opioid receptor agonist, DAMGO {[D-Ala2-MePhe4-Gly(ol5]enkephalin}. The main differences in morphological and biophysical membrane properties occurred among striatal sub-regions. MSSNs in the DLS were larger, had higher membrane capacitances and lower Rin (input resistances compared with cells in the VMS. RMPs (resting membrane potentials were similar among regions except for D2 cells in the NAcC, which displayed a significantly more depolarized RMP. In contrast, differences in frequency of spontaneous excitatory synaptic inputs were more prominent between cell types, with D2 cells receiving significantly more excitatory inputs than D1 cells, particularly in the VMS. Inhibitory inputs were not different between D1 and D2 cells. However, MSSNs in the VMS received more inhibitory inputs than those in the DLS. Acute application of DAMGO reduced the frequency of spontaneous excitatory and inhibitory postsynaptic currents, but the effect was greater in the VMS, in particular in the NAcS, where excitatory currents from D2 cells and inhibitory currents from D1 cells were inhibited by the largest amount. DAMGO also increased cellular excitability in the VMS, as shown by reduced threshold for evoking APs (action potentials. Together the present findings help elucidate the regional and cell-type-specific substrate of opioid actions in the striatum and point to the VMS as a critical mediator of DAMGO effects.

  17. CdSe magic-sized quantum dots incorporated in biomembrane models at the air-water interface composed of components of tumorigenic and non-tumorigenic cells.

    Science.gov (United States)

    Goto, Thiago E; Lopes, Carla C; Nader, Helena B; Silva, Anielle C A; Dantas, Noelio O; Siqueira, José R; Caseli, Luciano

    2016-07-01

    Cadmium selenide (CdSe) magic-sized quantum dots (MSQDs) are semiconductor nanocrystals with stable luminescence that are feasible for biomedical applications, especially for in vivo and in vitro imaging of tumor cells. In this work, we investigated the specific interaction of CdSe MSQDs with tumorigenic and non-tumorigenic cells using Langmuir monolayers and Langmuir-Blodgett (LB) films of lipids as membrane models for diagnosis of cancerous cells. Surface pressure-area isotherms and polarization modulation reflection-absorption spectroscopy (PM-IRRAS) showed an intrinsic interaction between the quantum dots, inserted in the aqueous subphase, and Langmuir monolayers constituted either of selected lipids or of tumorigenic and non-tumorigenic cell extracts. The films were transferred to solid supports to obtain microscopic images, providing information on their morphology. Similarity between films with different compositions representing cell membranes, with or without the quantum dots, was evaluated by atomic force microscopy (AFM) and confocal microscopy. This study demonstrates that the affinity of quantum dots for models representing cancer cells permits the use of these systems as devices for cancer diagnosis. PMID:27107554

  18. Hierarchical TiO{sub 2} submicron-sized spheres for enhanced power conversion efficiency in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hao [Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430062 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Guo, Zhiguang, E-mail: zguo@licp.cas.cn [Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430062 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2015-10-15

    Hierarchical TiO{sub 2} submicron-sized sphere scattering layer, with relatively large surface area and effective light scattering, shows enhanced power conversion efficiency in dye-sensitized solar cells. - Highlights: • Hierarchical TiO{sub 2} submicron-sized spheres (TiO{sub 2} HSSs) with diameters of 400–600 nm were synthesized. • The HSSs composed of nanoparticles of ∼14 nm have a relatively large surface area of ∼35 m{sup 2}/g. • DSC exhibited the highest cell efficiency (6.23%) compared with ones with pure P25 (5.50%) or HSS (2.00%) photoanodes. - Abstract: Hierarchical TiO{sub 2} submicron-sized spheres (TiO{sub 2} HSSs) with diameters of 400–600 nm were synthesized by a facile one-step solvothermal method in ethanol solvent. The HSSs composed of nanoparticles of ∼14 nm have a relatively large surface area of ∼35 m{sup 2}/g. When applied as the scattering overlayer in dye-sensitized solar cells (DSCs), such TiO{sub 2} HSSs effectively improved light harvesting and led to the increase of photocurrent in DSCs. Furthermore, bilayer-structured photoanode also provided fast electron transportation and long electron lifetime as confirmed by electrochemical impedance spectra. As a result, DSC based on P25 nanoparticle underlayer and HSS-2 overlayer exhibited the highest cell efficiency (6.23%) compared with ones with pure P25 (5.50%) or HSS-2 (2.00%) photoanodes.

  19. On the influence of cell size in physically-based distributed hydrological modelling to assess extreme values in water resource planning

    Directory of Open Access Journals (Sweden)

    M. Egüen

    2012-05-01

    Full Text Available This paper studies the influence of changing spatial resolution on the implementation of distributed hydrological modelling for water resource planning in Mediterranean areas. Different cell sizes were used to investigate variations in the basin hydrologic response given by the model WiMMed, developed in Andalusia (Spain, in a selected watershed. The model was calibrated on a monthly basis from the available daily flow data at the reservoir that closes the watershed, for three different cell sizes, 30, 100, and 500 m, and the effects of this change on the hydrological response of the basin were analysed by means of the comparison of the hydrological variables at different time scales for a 3-yr-period, and the effective values for the calibration parameters obtained for each spatial resolution. The variation in the distribution of the input parameters due to using different spatial resolutions resulted in a change in the obtained hydrological networks and significant differences in other hydrological variables, both in mean basin-scale and values distributed in the cell level. Differences in the magnitude of annual and global runoff, together with other hydrological components of the water balance, became apparent. This study demonstrated the importance of choosing the appropriate spatial scale in the implementation of a distributed hydrological model to reach a balance between the quality of results and the computational cost; thus, 30 and 100-m could be chosen for water resource management, without significant decrease in the accuracy of the simulation, but the 500-m cell size resulted in significant overestimation of runoff and consequently, could involve uncertain decisions based on the expected availability of rainfall excess for storage in the reservoirs. Particular values of the effective calibration parameters are also provided for this hydrological model and the study area.

  20. Thyroid size change by CT monitoring after sorafenib or sunitinib treatment in patients with renal cell carcinoma: Comparison with thyroid function

    International Nuclear Information System (INIS)

    Objective: Hypothyroidism is a common complication in patients receiving tyrosine kinase inhibitors. We evaluated the relationship between thyroid size evident on CT and thyroid function in patients with advanced renal cell carcinoma (RCC) receiving tyrosine kinase inhibitors. Materials and methods: Forty-two patients with metastatic RCC receiving tyrosine kinase inhibitors (sorafenib n = 25; sunitinib n = 17) and, followed-up for ≥12 months were eligible. Patients who had ever shown an elevated thyroid-stimulating hormone (TSH) level of >10 mU/l were defined as having “hypothyroidism”. CT scans were performed before, and 3, 6, 9, and 12 months after the start of treatment. The area of the thyroid in the maximum section at each examination was measured and compared with that before treatment. Using repeated-measures ANOVA, differences in thyroid size were compared over time between patients with and without “hypothyroidism”, in relation to the type of drug employed. Results: Twenty-one patients (sorafenib 9, sunitinib 12) developed “hypothyroidism” 95 ± 88 days (range 12–315 days) after the start of treatment. In such patients, the thyroid was reduced in size to 89 ± 16% after 3 months, 81 ± 21% after 6 months, 71 ± 21% after 9 months and 68 ± 21% after 12 months, whereas the patients without “hypothyroidism” maintained a thyroid size of 90 ± 12% even after 12 months (p = 0.0030). Among the patients with “hypothyroidism”, those treated with sunitinib tended to show greater thyroid size reduction than those with sorafenib (59 ± 23% vs. 79 ± 13%, after 12 months). Conclusion: Tyrosine kinase inhibitors cause an apparent thyroid size reduction in patients with “hypothyroidism”

  1. Thyroid size change by CT monitoring after sorafenib or sunitinib treatment in patients with renal cell carcinoma: Comparison with thyroid function

    Energy Technology Data Exchange (ETDEWEB)

    Kitajima, Kazuhiro, E-mail: kitajima@med.kobe-u.ac.jp [Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe 650-0017 (Japan); Takahashi, Satoru; Maeda, Tetsuo; Yoshikawa, Takeshi; Ohno, Yoshiharu; Fujii, Masahiko [Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe 650-0017 (Japan); Miyake, Hideaki; Fujisawa, Masato [Department of Urology, Kobe University Graduate School of Medicine, Kobe (Japan); Sugimura, Kazuro [Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe 650-0017 (Japan)

    2012-09-15

    Objective: Hypothyroidism is a common complication in patients receiving tyrosine kinase inhibitors. We evaluated the relationship between thyroid size evident on CT and thyroid function in patients with advanced renal cell carcinoma (RCC) receiving tyrosine kinase inhibitors. Materials and methods: Forty-two patients with metastatic RCC receiving tyrosine kinase inhibitors (sorafenib n = 25; sunitinib n = 17) and, followed-up for ≥12 months were eligible. Patients who had ever shown an elevated thyroid-stimulating hormone (TSH) level of >10 mU/l were defined as having “hypothyroidism”. CT scans were performed before, and 3, 6, 9, and 12 months after the start of treatment. The area of the thyroid in the maximum section at each examination was measured and compared with that before treatment. Using repeated-measures ANOVA, differences in thyroid size were compared over time between patients with and without “hypothyroidism”, in relation to the type of drug employed. Results: Twenty-one patients (sorafenib 9, sunitinib 12) developed “hypothyroidism” 95 ± 88 days (range 12–315 days) after the start of treatment. In such patients, the thyroid was reduced in size to 89 ± 16% after 3 months, 81 ± 21% after 6 months, 71 ± 21% after 9 months and 68 ± 21% after 12 months, whereas the patients without “hypothyroidism” maintained a thyroid size of 90 ± 12% even after 12 months (p = 0.0030). Among the patients with “hypothyroidism”, those treated with sunitinib tended to show greater thyroid size reduction than those with sorafenib (59 ± 23% vs. 79 ± 13%, after 12 months). Conclusion: Tyrosine kinase inhibitors cause an apparent thyroid size reduction in patients with “hypothyroidism”.

  2. Ablation of the mTORC2 component rictor in brain or Purkinje cells affects size and neuron morphology

    OpenAIRE

    Thomanetz, Venus; Angliker, Nico; Cloëtta, Dimitri; Lustenberger, Regula M.; Schweighauser, Manuel; Oliveri, Filippo; Suzuki, Noboru; Rüegg, Markus A

    2013-01-01

    The mammalian target of rapamycin (mTOR) assembles into two distinct multi-protein complexes called mTORC1 and mTORC2. Whereas mTORC1 is known to regulate cell and organismal growth, the role of mTORC2 is less understood. We describe two mouse lines that are devoid of the mTORC2 component rictor in the entire central nervous system or in Purkinje cells. In both lines neurons were smaller and their morphology and function were strongly affected. The phenotypes were accompanied by loss of activ...

  3. Randomized clinical trial of mast cell inhibition in patients with a medium-sized abdominal aortic aneurysm

    DEFF Research Database (Denmark)

    Sillesen, H; Eldrup, N; Hultgren, R;

    2015-01-01

    BACKGROUND: Abdominal aortic aneurysm (AAA) is thought to develop as a result of inflammatory processes in the aortic wall. In particular, mast cells are believed to play a central role. The AORTA trial was undertaken to investigate whether the mast cell inhibitor, pemirolast, could retard the...... surgery, diabetes mellitus, and severe concomitant disease with a life expectancy of less than 2 years. Included patients were treated with 10, 25 or 40 mg pemirolast, or matching placebo for 52 weeks. The primary endpoint was change in aortic diameter as measured from leading edge adventitia at the...

  4. Study of the effect of Titanium dioxide nano particle size on efficiency of the dye-sensitized Solar cell using natural Pomegranate juice

    Directory of Open Access Journals (Sweden)

    A Behjat

    2015-01-01

    Full Text Available Dye-sensitized solar cell (DSSC using natural Pomegranate juice as dye-sensitizeris fabricated and characterized. DSSCS consist of a working electrode, a redox electrolyte containing iodide and tri-iodide ions and a counter electrode. A nanocrystalline TiO2 semiconductor with a wide band-gap coated with a monolayer dye-sensitizer is used as working electrode. The effect of titanium dioxide (TiO2 nanoparticle size on efficiency of the DSSC based Pomegranate juice as a sensitizer is studied. For monolayer structure, we used two sizes of TiO2 nanoparticle (25 nm and 100 nm and a mixture of these two sizes. The highest efficiency of 0.61% was obtained with mixture of 25 and 100 nm TiO2 nano-particles in working electrode. For double-layer structure, we used 100 and 400 nm size TiO2 particles as light-scattering. The best efficiency was obtained using 400 nm TiO2 as light-scattering particles.

  5. Enhanced magnetic resonance imaging and staining of cancer cells using ferrimagnetic H-ferritin nanoparticles with increasing core size

    OpenAIRE

    Cai Y; Cao CQ; He XQ; Yang CY; Tian LX; Zhu RX; Pan YX

    2015-01-01

    Yao Cai,1–3 Changqian Cao,1,2 Xiaoqing He,1 Caiyun Yang,1–3 Lanxiang Tian,1,2 Rixiang Zhu,2 Yongxin Pan1,21France–China Bio-Mineralization and Nano-Structures Laboratory, 2Paleomagnetism and Geochronology Laboratory, Key Laboratory of the Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, 3University of Chinese Academy of Sciences, Beijing, People’s Republic of ChinaPurpose: This study is to demonstrate the nanoscale size eff...

  6. Soy biodiesel and petrodiesel emissions differ in size, chemical composition and stimulation of inflammatory responses in cells and animals.

    Science.gov (United States)

    Fukagawa, Naomi K; Li, Muyao; Poynter, Matthew E; Palmer, Brian C; Parker, Erin; Kasumba, John; Holmén, Britt A

    2013-01-01

    Debate about the biological effects of biodiesel exhaust emissions exists due to variation in methods of exhaust generation and biological models used to assess responses. Because studies in cells do not necessarily reflect the integrated response of a whole animal, experiments were conducted in two human cell lines representing bronchial epithelial cells and macrophages and female mice using identical particle suspensions of raw exhaust generated by a Volkswagen light-duty diesel engine using petrodiesel (B0) and a biodiesel blend (B20: 20% soy biodiesel/80% B0 by volume). Tailpipe particle emissions measurement showed B0 generated two times more particle mass, larger ultrafine particle number distribution modes, and particles of more nonpolar organic composition than the B20 fuel. Biological assays (inflammatory mediators, oxidative stress biomarkers) demonstrated that particulate matter (PM) generated by combustion of the two fuels induced different responses in in vitro and in vivo models. Concentrations of inflammatory mediators (Interleukin-6, IL-6; Interferon-gamma-induced Protein 10, IP-10; Granulocyte-stimulating factor, G-CSF) in the medium of B20-treated cells and in bronchoalveolar lavage fluid of mice exposed to B20 were ∼20-30% higher than control or B0 PM, suggesting that addition of biodiesel to diesel fuels will reduce PM emissions but not necessarily adverse health outcomes. PMID:24053625

  7. Tuning of the temperature window for unit-cell and pore-size enlargement in face-centered-cubic large-mesopore silicas templated by swollen block copolymer micelles.

    Science.gov (United States)

    Li, Yingyu; Yi, Jinhui; Kruk, Michal

    2015-09-01

    The unit-cell size and pore diameter as functions of temperature are investigated in the syntheses of FDU-12 silicas with face-centered cubic structure templated by Pluronic (PEO-PPO-PEO) block copolymer micelles swollen by toluene. The temperature range in which the unit-cell size and pore size strongly increase as temperature decreases is correlated with the critical micelle temperature (CMT) of the surfactant. While Pluronic F127 affords a wide range of unit-cell parameters (28-51 nm) and pore diameters (16-32 nm), it renders moderately enlarged pore sizes at 25 °C. The use of Pluronic F108 with higher CMT affords FDU-12 with very large unit-cell size (∼49 nm) and large pore diameter (27 nm) at 23 °C. Large unit-cell size (40-41 nm) and pore size (22 nm) were obtained even at 25 °C. The application of Pluronics F87 and F88 with much smaller molecular weights and higher CMTs also allows one to synthesize FDU-12 with quite large unit-cell parameters and pore sizes at room temperature. The present work demonstrates that one can judiciously select Pluronic surfactants with appropriate CMT to shift the temperature range in which the pore diameter is readily tunable. PMID:26178137

  8. Preparation of onion-like Pt-terminated Pt-Cu bimetallic nano-sized electrocatalysts for oxygen reduction reaction in fuel cells

    Science.gov (United States)

    Lim, Taeho; Kim, Ok-Hee; Sung, Yung-Eun; Kim, Hyun-Jong; Lee, Ho-Nyun; Cho, Yong-Hun; Kwon, Oh Joong

    2016-06-01

    Onion-like Pt-terminated Pt-Cu bimetallic nano-sized electrocatalysts (Pt/Cu/Pt/C) were synthesized by using an electroless deposition method. The synthesized Pt/Cu/Pt/C consisted of a Pt-enriched shell, a sandwiched Pt-Cu alloy layer, and a Pt core. The Pt/Cu/Pt/C showed higher electrocatalytic activity toward oxygen reduction reaction in half-cell test than that of commercial Pt/C due to an electronic structure change in the Pt-enriched shell, resulting from the sandwiched Pt-Cu alloy layer underneath. The stability of the Pt/Cu/Pt/C was examined by using both half-cell and single-cell degradation tests. In both tests, the Pt/Cu/Pt/C exhibited stronger resistance to catalyst degradation than that of the commercial Pt/C. It is notable that cell performance with the Pt/Cu/Pt/C was fully recovered by N2 purging after single-cell degradation testing, indicating there was no permanent damage to the electrocatalyst during the test. It is suggested that thermodynamically-stable structure of the Pt/Cu/Pt/C contributed to the improved stability.

  9. Cell size and geometry of spinal cord motoneurons in the adult cat following the intramuscular injection of adriamycin: comparison with data from aged cats.

    Science.gov (United States)

    Liu, R H; Yamuy, J; Engelhardt, J K; Xi, M C; Morales, F R; Chase, M H

    1996-10-28

    Adriamycin (ADM), an antineoplastic antibiotic, when injected intramuscularly, is taken up by motoneuron axonal terminals and retrogradely transported to the motoneuron soma where it exerts its neurotoxic effect. In the present study, ADM was injected into the hindlimb muscles of five adult cats. Measurements of the electrophysiological properties of the lumbar motoneurons innervating these muscles were obtained using intracellular techniques. Based upon these data the equivalent cylinder model of motoneurons was employed to evaluate ADM-induced changes in cell size and cell geometry. The size of cell somas in the ventral horn was also measured using light microscopy and computer imaging software. There were significant increases in the membrane time constant (25%) and input resistance (50%) in motoneurons whose muscles were treated with ADM (ADM-MNs) compared with data from control motoneurons (control-MNs). The increase in membrane time constant is attributed to an increase in membrane resistance; the increase in input resistance appears to depend upon both an increase in membrane resistance and a decrease in total cell surface area. Cell capacitance, which is proportional to the total cell surface area, was significantly reduced (15%) in ADM-MNs. Calculations based on cable theory indicate that while there was no significant change in the length of the equivalent cylinder for ADM-MNs, there was a significant decrease (17%) in the diameter of the equivalent cylinder. These data indicate that there is a decrease in total cell surface area which can be attributed to the shrinkage of branches throughout the dendritic tree. There was also a small (7%) but statistically significant decrease in the electrotonic length of ADM-MNs. Morphological analysis also revealed that the mean cross-sectional area of the somas of those ventral horn neurons which are likely to correspond to the motoneuron population was significantly reduced on the ADM-treated side compared to that

  10. Contact size scaling of a W-contact phase-change memory cell based on numerical simulation

    International Nuclear Information System (INIS)

    In the design of phase-change memory (PCM), it is important to perform numerical simulations to predict the performances of different device structures. This work presents a numerical simulation using a coupled system including Poisson's equation, the current continuity equation, the thermal conductivity equation, and phase-change dynamics to simulate the thermal and electric characteristics of phase-change memory. This method discriminates the common numerical simulation of PCM cells, from which it applies Possion's equation and current continuity equations instead of the Laplace equation to depict the electric characteristics of PCM cells, which is more adoptable for the semiconductor characteristics of phase-change materials. The results show that the simulation agrees with the measurement, and the scalability of PCM is predicted.

  11. Development of an Advanced Two-Dimensional Thermal Model for Large size Lithium-ion Pouch Cells

    International Nuclear Information System (INIS)

    In this work, a LiFePO4/graphite lithium-ion pouch cell with a rated capacity of 45Ah has been used and a two dimensional thermal model is developed to predict the cell temperature distribution over the surface of the battery, this model requires less input parameters and still has high accuracy. The used input parameters are the heat generation and thermal properties. The ANSYS FLUENT software has been used to solve the models. In addition, a new estimation tool has been developed for estimation of the thermal model parameters. Furthermore, the thermal behavior of the proposed battery has been investigated at different environmental conditions as well as during the abuse conditions. Thermal runaway is investigated in depth by the model

  12. Body size and risk of renal cell carcinoma in the European Prospective Investigation into Cancer and Nutrition (EPIC)

    OpenAIRE

    Pischon, T.; Lahmann, PH; Boeing, H.; Tjonneland, A; Halkjaer, J; Overvad, K; Klipstein-Grobusch, K.; Linseisen, J.; N. Becker; Trichopoulou, A.; Benetou, V; Trichopoulos, D.; Sieri, S.; Palli, D.; Tumino, R.

    2006-01-01

    Previous studies suggest that obesity is related to increased risk of renal cell carcinoma (RCC); however, only a few studies report on measures of central vs. peripheral adiposity. We examined the association between anthropometric measures, including waist and hip circumference and RCC risk among 348,550 men and women free of cancer at baseline from 8 countries of the European Prospective Investigation into Cancer and Nutrition (EPIC). During 6.0 years of follow-up we identified 287 inciden...

  13. Number and size of human X chromosome fragments transferred to mouse cells by chromosome-mediated gene transfer.

    OpenAIRE

    Olsen, A S; McBride, O W; Moore, D. E.

    1981-01-01

    Labeled probes of unique-sequence human X chromosomal deoxyribonucleic acid, prepared by two different procedures, were used to measure the amount of human X chromosomal deoxyribonucleic acid in 12 mouse cell lines expressing human hypoxanthine phosphoribosyltransferase after chromosome-mediated gene transfer. The amount of X chromosomal deoxyribonucleic acid detected by this procedure ranged from undetectable levels in the three stable transformants and some unstable transformants examined t...

  14. Circulating tumor cells in breast cancer at the diagnosis are associated with lymph node involvement, tumor size and negative ER status

    Directory of Open Access Journals (Sweden)

    P. Ferro

    2011-01-01

    Full Text Available We investigated the association of circulating tumor cells (CTC with poor prognostic markers in breast cancer (BC at time of diagnosis. Peripheral blood (PB samples from 190 patients with invasive BC, 12 patients with in situ BC, before theraphy and/or surgery, and 330 from patients without BC were tested for CTCs by RT-PCR for human mammaglobin (hMAM. hMAM was expressed only in PB of invasive BC (9.5% and a significant correlation was found between CTCs with lymph node involvement, tumour size and negative ER. We conclude that CTC detention in invasive BC may be an additional poor prognostic indicator.

  15. The use of nylon and glass fiber filter separators with different pore sizes in air-cathode single-chamber microbial fuel cells

    KAUST Repository

    Zhang, Xiaoyuan

    2010-01-01

    Separators are needed in microbial fuel cells (MFCs) to reduce electrode spacing and preventing electrode short circuiting. The use of nylon and glass fiber filter separators in single-chamber, air-cathode MFCs was examined for their effect on performance. Larger pore nylon mesh were used that had regular mesh weaves with pores ranging from 10 to 160 μm, while smaller pore-size nylon filters (0.2-0.45 μm) and glass fiber filters (0.7-2.0 μm) had a more random structure. The pore size of both types of nylon filters had a direct and predictable effect on power production, with power increasing from 443 ± 27 to 650 ± 7 mW m-2 for pore sizes of 0.2 and 0.45 μm, and from 769 ± 65 to 941 ± 47 mW m-2 for 10 to 160 μm. In contrast, changes in pore sizes of the glass fiber filters resulted in a relatively narrow change in power (732 ± 48 to 779 ± 43 mW m-2) for pore sizes of 0.7 to 2 μm. An ideal separator should increase both power density and Coulombic efficiency (CE). However, CEs measured for the different separators were inversely correlated with power production, demonstrating that materials which reduced the oxygen diffusion into the reactor also hindered proton transport to the cathode, reducing power production through increased internal resistance. Our results highlight the need to develop separators that control oxygen transfer and facilitate proton transfer to the cathode. © 2010 The Royal Society of Chemistry.

  16. Fine Tuning of Nanocrystal and Pore Sizes of TiO2 Submicrospheres toward High Performance Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Li, Zhao-Qian; Ding, Yong; Mo, Li-E; Hu, Lin-Hua; Wu, Ji-Huai; Dai, Song-Yuan

    2015-10-14

    In general, the properties and performance of mesoporous TiO2 are greatly dependent on its crystal size, crystallinity, porosity, surface area, and morphology; in this regard, design and fine-tuning the crystal and pore sizes of the TiO2 submicrospheres and investigating the effect of these factors on the properties and photoelectric performance of dye-sensitized solar cells (DSSCs) is essential. In this work, uniform TiO2 submicrospheres were synthesized by a two-step procedure containing hydrolysis and solvothermal process. The crystal and pore sizes of the TiO2 submicrospheres were fine-tuned and controlled in a narrow range by adjusting the quantity of NH4OH during the solvothermal process. The effect of crystal and pore size of TiO2 submicrosphere on the performance of the DSSCs and their properties including dye-loading capacity, light scattering effect, power conversion efficiency (PCE), incident photon-to-electron conversion efficiencies (IPCEs), and electron recombination were compared and analyzed. The results show that increasing pore size plays a more significant role in improving the dye-loading capacity and PCE than increasing surface area, and an overall PCE value of 8.62% was obtained for the device with a 7.0 μm film thickness based on the TiO2 submicrospheres treated with 0.6 mL of NH4OH. Finally, the best TiO2 submicrosphere based photoanode film was optimized by TiCl4 treatment, and increasing film thickness and a remarkable PCE up to 11.11% were achieved. PMID:26393366

  17. Differential changes in size distribution of xyloglucan in the cell walls of gravitropically responding Pisum sativum epicotyls

    Science.gov (United States)

    Talbott, L. D.; Pickard, B. G.

    1994-01-01

    Growth-related change in the size distribution of hemicellulosic wall polymers during the gravitropic curvature response of intact pea (Pisum sativum L. cv Alaska) epicotyls was examined by gel-filtration chromatography. The gravitropic response was characterized by the appearance of curvature 20 to 30 min after horizontal placement, with 35 degrees of curvature attained by 80 min. Correlated with the onset of curvature, on the upper side of the epicotyl, there was a conspicuous transient increase in the abundance of relatively large hemicellulosic xyloglucan polymers, similar to increases previously found under conditions where diminished wall extensibility was expected. On the lower side there was a moderate, slower, and longer-term increase in abundance of small xyloglucan, similar to changes previously found in connection with auxin-stimulated growth responses. Both shifts occurred primarily in the epidermis. They appear to represent two coordinated physiological mechanisms contributing to differential growth.

  18. Role of metal/silicon semiconductor contact engineering for enhanced output current in micro-sized microbial fuel cells

    KAUST Repository

    Mink, Justine E.

    2013-11-25

    We show that contact engineering plays an important role to extract the maximum performance from energy harvesters like microbial fuel cells (MFCs). We experimented with Schottky and Ohmic methods of fabricating contact areas on silicon in an MFC contact material study. We utilized the industry standard contact material, aluminum, as well as a metal, whose silicide has recently been recognized for its improved performance in smallest scale integration requirements, cobalt. Our study shows that improvements in contact engineering are not only important for device engineering but also for microsystems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Thermal-fluid and electrochemical modeling and performance study of a planar solid oxide electrolysis cell : analysis on SOEC resistances, size, and inlet flow conditions.

    Energy Technology Data Exchange (ETDEWEB)

    Yildiz, B.; Smith, J.; Sofu, T.; Nuclear Engineering Division

    2008-06-25

    Argonne National Laboratory and Idaho National Laboratory researchers are analyzing the electrochemical and thermal-fluid behavior of solid oxide electrolysis cells (SOECs) for high temperature steam electrolysis using computational fluid dynamics (CFD) techniques. The major challenges facing commercialization of steam electrolysis technology are related to efficiency, cost, and durability of the SOECs. The goal of this effort is to guide the design and optimization of performance for high temperature electrolysis (HTE) systems. An SOEC module developed by FLUENT Inc. as part of their general CFD code was used for the SOEC analysis by INL. ANL has developed an independent SOEC model that combines the governing electrochemical mechanisms based on first principals to the heat transfer and fluid dynamics in the operation of SOECs. The ANL model was embedded into the commercial STAR-CD CFD software, and is being used for the analysis of SOECs by ANL. The FY06 analysis performed by ANL and reported here covered the influence of electrochemical properties, SOEC component resistances and their contributing factors, SOEC size and inlet flow conditions, and SOEC flow configurations on the efficiency and expected durability of these systems. Some of the important findings from the ANL analysis are: (1) Increasing the inlet mass flux while going to larger cells can be a compromise to overcome increasing thermal and current density gradients while increasing the cell size. This approach could be beneficial for the economics of the SOECs; (2) The presence of excess hydrogen at the SOEC inlet to avoid Ni degradation can result in a sizeable decrease in the process efficiency; (3) A parallel-flow geometry for SOEC operation (if such a thing be achieved without sealing problems) yields smaller temperature gradients and current density gradients across the cell, which is favorable for the durability of the cells; (4) Contact resistances can significantly influence the total cell

  20. Upconversion NaYF4 Nanoparticles for Size Dependent Cell Imaging and Concentration Dependent Detection of Rhodamine B

    Directory of Open Access Journals (Sweden)

    Shigang Hu

    2015-01-01

    Full Text Available Upconversion nanoparticles (UCNPs based on NaYF4 nanocrystals with strong upconversion luminescence are synthesized by the solvothermal method. The emission color of these NaYF4 upconversion nanoparticles can be easily modulated by the doping. These NaYF4 upconversion nanocrystals can be employed as fluorescence donors to pump fluorescent organic molecules. For example, the efficient luminescence resonant energy transfer (LRET can be achieved by controlling the distance between NaYF4:Yb3+/Er3+ UCNPs and Rhodamine B (RB. NaYF4:Yb3+/Er3+ UCNPs can emit green light at the wavelength of ~540 nm while RB can efficiently absorb the green light of ~540 nm to emit red light of 610 nm. The LRET efficiency is highly dependent on the concentration of NaYF4 upconversion fluorescent donors. For the fixed concentration of 3.2 µg/mL RB, the optimal concentration of NaYF4:Yb3+/Er3+ UCNPs is equal to 4 mg/mL which generates the highest LRET signal ratio. In addition, it is addressed that the upconversion nanoparticles with diameter of 200 nm are suitable for imaging the cells larger than 10 µm with clear differentiation between cell walls and cytoplasm.

  1. Dynamic Morphological Changes Induced By GM1 and Protein Interactions on the Surface of Cell-Sized Liposomes

    Directory of Open Access Journals (Sweden)

    Masahiro Takagi

    2013-06-01

    Full Text Available It is important to understand the physicochemical mechanisms that are responsible for the morphological changes in the cell membrane in the presence of various stimuli such as osmotic pressure. Lipid rafts are believed to play a crucial role in various cellular processes. It is well established that Ctb (Cholera toxin B subunit recognizes and binds to GM1 (monosialotetrahexosylganglioside on the cell surface with high specificity and affinity. Taking advantage of Ctb-GM1 interaction, we examined how Ctb and GM1 molecules affect the dynamic movement of liposomes. GM1 a natural ligand for cholera toxin, was incorporated into liposome and the interaction between fluorescent Ctb and the liposome was analyzed. The interaction plays an important role in determining the various surface interaction phenomena. Incorporation of GM1 into membrane leads to an increase of the line tension leading to either rupture of liposome membrane or change in the morphology of the membrane. This change in morphology was found to be GM1 concentration specific. The interaction between Ctb-GM1 leads to fast and easy rupture or to morphological changes of the liposome. The interactions of Ctb and the glycosyl chain are believed to affect the surface and the curvature of the membrane. Thus, the results are highly beneficial in the study of signal transduction processes.

  2. Aberrantly Over-Expressed TRPM8 Channels in Pancreatic Adenocarcinoma: Correlation with Tumor Size/Stage and Requirement for Cancer Cells Invasion

    Directory of Open Access Journals (Sweden)

    Nelson S. Yee

    2014-05-01

    Full Text Available The transient receptor potential melastatin-subfamily member 8 (TRPM8 channels control Ca2+ homeostasis. Recent studies indicate that TRPM8 channels are aberrantly expressed and required for cellular proliferation in pancreatic adenocarcinoma. However, the functional significance of TRPM8 in pancreatic tissues is mostly unknown. The objectives of this study are to examine the expression of TRPM8 in various histopathological types of pancreatic tissues, determine its clinical significance in pancreatic adenocarcinoma, and investigate its functional role in cancer cells invasion. We present evidence that, in normal pancreatic tissues, anti-TRPM8 immunoreactivity is detected in the centroacinar cells and the islet endocrine cells. In pre-malignant pancreatic tissues and malignant neoplasms, TRPM8 is aberrantly expressed to variable extents. In the majority of pancreatic adenocarcinoma, TRPM8 is expressed at moderate or high levels, and anti-TRPM8 immunoreactivity positively correlates with the primary tumor size and stage. In the pancreatic adenocarcinoma cell lines that express relatively high levels of TRPM8, short hairpin RNA-mediated interference of TRPM8 expression impaired their ability of invasion. These data suggest that aberrantly expressed TRPM8 channels play contributory roles in pancreatic tumor growth and metastasis, and support exploration of TRPM8 as a biomarker and target of pancreatic adenocarcinoma.

  3. Clinical introduction of Monte Carlo treatment planning: A different prescription dose for non-small cell lung cancer according to tumor location and size

    International Nuclear Information System (INIS)

    Purpose: To provide a prescription dose for Monte Carlo (MC) treatment planning in patients with non-small-cell lung cancer according to tumor size and location. Methods: Fifty-three stereotactic radiotherapy plans designed using the equivalent path-length (EPL) algorithm were re-calculated using MC. Plans were compared by the minimum dose to 95% of the PTV (D95), the heterogeneity index (HI) and the mean dose to organs at risk (OARs). Based on changes in D95, the prescription dose was converted from EPL to MC. Based on changes in HI, we examined the feasibility of MC prescription to plans re-calculated but not re-optimized with MC. Results: The MC fraction dose for peripheral tumors is 16-18 Gy depending on tumor size. For central tumors the MC dose was reduced less than for peripheral tumors. The HI decreased on average by 4-9% in peripheral tumors and 3-5% in central tumors. The mean dose to OARs was lower for MC than EPL, and correlated strongly (R2 = 0.98-0.99). Conclusion: For the conversion from EPL to MC we recommend a separate prescription dose according to tumor size. MC optimization is not required if a HI ≥ 70% is accepted. Dose constraints to OARs can be easily converted due to the high EPL-MC correlation.

  4. Influence of extracellular pH on growth, viability, cell size, acidification activity, and intracellular pH of Lactococcus lactis in batch fermentations.

    Science.gov (United States)

    Hansen, Gunda; Johansen, Claus Lindvald; Marten, Gunvor; Wilmes, Jacqueline; Jespersen, Lene; Arneborg, Nils

    2016-07-01

    In this study, we investigated the influence of three extracellular pH (pHex) values (i.e., 5.5, 6.5, and 7.5) on the growth, viability, cell size, acidification activity in milk, and intracellular pH (pHi) of Lactococcus lactis subsp. lactis DGCC1212 during pH-controlled batch fermentations. A universal parameter (e.g., linked to pHi) for the description or prediction of viability, specific acidification activity, or growth behavior at a given pHex was not identified. We found viability as determined by flow cytometry to remain high during all growth phases and irrespectively of the pH set point. Furthermore, regardless of the pHex, the acidification activity per cell decreased over time which seemed to be linked to cell shrinkage. Flow cytometric pHi determination demonstrated an increase of the averaged pHi level for higher pH set points, while the pH gradient (pHi-pHex) and the extent of pHi heterogeneity decreased. Cells maintained positive pH gradients at a low pHex of 5.5 and even during substrate limitation at the more widely used pHex 6.5. Moreover, the strain proved able to grow despite small negative or even absent pH gradients at a high pHex of 7.5. The larger pHi heterogeneity at pHex 5.5 and 6.5 was associated with more stressful conditions resulting, e.g., from higher concentrations of non-dissociated lactic acid, while the low pHi heterogeneity at pHex 7.5 most probably corresponded to lower concentrations of non-dissociated lactic acid which facilitated the cells to reach the highest maximum active cell counts of the three pH set points. PMID:27020293

  5. PLGA-based microparticles loaded with bacterial-synthesized prodigiosin for anticancer drug release: Effects of particle size on drug release kinetics and cell viability.

    Science.gov (United States)

    Obayemi, J D; Danyuo, Y; Dozie-Nwachukwu, S; Odusanya, O S; Anuku, N; Malatesta, K; Yu, W; Uhrich, K E; Soboyejo, W O

    2016-09-01

    This paper presents the synthesis and physicochemical characterization of biodegradable poly (d,l-lactide-co-glycolide) (PLGA)-based microparticles that are loaded with bacterial-synthesized prodigiosin drug obtained from Serratia marcescens subsp. Marcescens bacteria for controlled anticancer drug delivery. The micron-sized particles were loaded with anticancer drugs [prodigiosin (PG) and paclitaxel (PTX) control] using a single-emulsion solvent evaporation technique. The encapsulation was done in the presence of PLGA (as a polymer matrix) and poly-(vinyl alcohol) (PVA) (as an emulsifier). The effects of processing conditions (on the particle size and morphology) are investigated along with the drug release kinetics and drug-loaded microparticle degradation kinetics. The localization and apoptosis induction by prodigiosin in breast cancer cells is also elucidated along with the reduction in cell viability due to prodigiosin release. The implication of this study is for the potential application of prodigiosin PLGA-loaded microparticles for controlled delivery of cancer drug and treatment to prevent the regrowth or locoregional recurrence, following surgical resection of triple negative breast tumor. PMID:27207038

  6. Highly narrow nanogap-containing Au@Au core-shell SERS nanoparticles: size-dependent Raman enhancement and applications in cancer cell imaging

    Science.gov (United States)

    Hu, Chongya; Shen, Jianlei; Yan, Juan; Zhong, Jian; Qin, Weiwei; Liu, Rui; Aldalbahi, Ali; Zuo, Xiaolei; Song, Shiping; Fan, Chunhai; He, Dannong

    2016-01-01

    Cellular imaging technologies employing metallic surface-enhanced Raman scattering (SERS) tags have gained much interest toward clinical diagnostics, but they are still suffering from poor controlled distribution of hot spots and reproducibility of SERS signals. Here, we report the fabrication and characterization of high narrow nanogap-containing Au@Au core-shell SERS nanoparticles (GCNPs) for the identification and imaging of proteins overexpressed on the surface of cancer cells. First, plasmonic nanostructures are made of gold nanoparticles (~15 nm) coated with gold shells, between which a highly narrow and uniform nanogap (~1.1 nm) is formed owing to polyA anchored on the Au cores. The well controlled distribution of Raman reporter molecules, such as 4,4'-dipyridyl (44DP) and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), are readily encoded in the nanogap and can generate strong, reproducible SERS signals. In addition, we have investigated the size-dependent SERS activity of GCNPs and found that with the same laser wavelength, the Raman enhancement discriminated between particle sizes. The maximum Raman enhancement was achieved at a certain threshold of particle size (~76 nm). High narrow nanogap-containing Au@Au core-shell SERS tags (GCTs) were prepared via the functionalization of hyaluronic acid (HA) on GCNPs, which recognized the CD44 receptor, a tumor-associated surface biomarker. And it was shown that GCTs have a good targeting ability to tumour cells and promising prospects for multiplex biomarker detection.Cellular imaging technologies employing metallic surface-enhanced Raman scattering (SERS) tags have gained much interest toward clinical diagnostics, but they are still suffering from poor controlled distribution of hot spots and reproducibility of SERS signals. Here, we report the fabrication and characterization of high narrow nanogap-containing Au@Au core-shell SERS nanoparticles (GCNPs) for the identification and imaging of proteins overexpressed on

  7. Adipose-derived mesenchymal stem cells markedly attenuate brain infarct size and improve neurological function in rats

    Directory of Open Access Journals (Sweden)

    Sun Cheuk-Kwan

    2010-06-01

    Full Text Available Abstract Background The therapeutic effect of adipose-derived mesenchymal stem cells (ADMSCs on brain infarction area (BIA and neurological status in a rat model of acute ischemic stroke (IS was investigated. Methods Adult male Sprague-Dawley (SD rats (n = 30 were divided into IS plus intra-venous 1 mL saline (at 0, 12 and 24 h after IS induction (control group and IS plus intra-venous ADMSCs (2.0 × 106 (treated interval as controls (treatment group after occlusion of distal left internal carotid artery. The rats were sacrificed and brain tissues were harvested on day 21 after the procedure. Results The results showed that BIA was larger in control group than in treatment group (p Conclusions ADMSC therapy significantly limited BIA and improved sensorimotor dysfunction after acute IS.

  8. Biocompatibility, endocytosis, and intracellular trafficking of mesoporous silica and polystyrene nanoparticles in ovarian cancer cells: effects of size and surface charge groups

    Directory of Open Access Journals (Sweden)

    Ekkapongpisit M

    2012-07-01

    Full Text Available Maneerat Ekkapongpisit,1 Antonino Giovia,1 Carlo Follo,1 Giuseppe Caputo,2,3 Ciro Isidoro11Laboratory of Molecular Pathology and Nanobioimaging, Department of Health Sciences, Università del Piemonte Orientale “A Avogadro”, Novara, 2Dipartimento di Chimica dell’Università di Torino, Torino, 3Cyanine Technology SpA, Torino, ItalyBackground and methods: Nanoparticles engineered to carry both a chemotherapeutic drug and a sensitive imaging probe are valid tools for early detection of cancer cells and to monitor the cytotoxic effects of anticancer treatment simultaneously. Here we report on the effect of size (10–30 nm versus 50 nm, type of material (mesoporous silica versus polystyrene, and surface charge functionalization (none, amine groups, or carboxyl groups on biocompatibility, uptake, compartmentalization, and intracellular retention of fluorescently labeled nanoparticles in cultured human ovarian cancer cells. We also investigated the involvement of caveolae in the mechanism of uptake of nanoparticles.Results: We found that mesoporous silica nanoparticles entered via caveolae-mediated endocytosis and reached the lysosomes; however, while the 50 nm nanoparticles permanently resided within these organelles, the 10 nm nanoparticles soon relocated in the cytoplasm. Naked 10 nm mesoporous silica nanoparticles showed the highest and 50 nm carboxyl-modified mesoporous silica nanoparticles the lowest uptake rates, respectively. Polystyrene nanoparticle uptake also occurred via a caveolae-independent pathway, and was negatively affected by serum. The 30 nm carboxyl-modified polystyrene nanoparticles did not localize in lysosomes and were not toxic, while the 50 nm amine-modified polystyrene nanoparticles accumulated within lysosomes and eventually caused cell death. Ovarian cancer cells expressing caveolin-1 were more likely to endocytose these nanoparticles.Conclusion: These data highlight the importance of considering both the

  9. The Impact of Tumor Size on Outcomes After Stereotactic Body Radiation Therapy for Medically Inoperable Early-Stage Non-Small Cell Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Allibhai, Zishan [Department of Radiation Oncology, Princess Margaret Cancer Centre, Toronto (Canada); Taremi, Mojgan [Department of Radiation Oncology, Stronach Regional Cancer Centre, Newmarket (Canada); Bezjak, Andrea; Brade, Anthony; Hope, Andrew J.; Sun, Alexander [Department of Radiation Oncology, Princess Margaret Cancer Centre, Toronto (Canada); Cho, B.C. John, E-mail: john.cho@rmp.uhn.on.ca [Department of Radiation Oncology, Princess Margaret Cancer Centre, Toronto (Canada)

    2013-12-01

    Purpose: Stereotactic body radiation therapy for medically inoperable early-stage non-small cell lung cancer (NSCLC) offers excellent control rates. Most published series deal mainly with small (usually <4 cm), peripheral, solitary tumors. Larger tumors are associated with poorer outcomes (ie, lower control rates, higher toxicity) when treated with conventional RT. It is unclear whether SBRT is sufficiently potent to control these larger tumors. We therefore evaluated and examined the influence of tumor size on treatment outcomes after SBRT. Methods and Materials: Between October 2004 and October 2010, 185 medically inoperable patients with early (T1-T2N0M0) NSCLC were treated on a prospective research ethics board-approved single-institution protocol. Prescription doses were risk-adapted based on tumor size and location. Follow-up included prospective assessment of toxicity (as per Common Terminology Criteria for Adverse Events, version 3.0) and serial computed tomography scans. Patterns of failure, toxicity, and survival outcomes were calculated using Kaplan-Meier method, and the significance of tumor size (diameter, volume) with respect to patient, treatment, and tumor factors was tested. Results: Median follow-up was 15.2 months. Tumor size was not associated with local failure but was associated with regional failure (P=.011) and distant failure (P=.021). Poorer overall survival (P=.001), disease-free survival (P=.001), and cause-specific survival (P=.005) were also significantly associated with tumor size (with tumor volume more significant than diameter). Gross tumor volume and planning target volume were significantly associated with grade 2 or worse radiation pneumonitis. However, overall rates of grade ≥3 pneumonitis were low and not significantly affected by tumor or target size. Conclusions: Currently employed stereotactic body radiation therapy dose regimens can provide safe effective local therapy even for larger solitary NSCLC tumors (up to 5.7 cm

  10. Effects of carbon brush anode size and loading on microbial fuel cell performance in batch and continuous mode

    KAUST Repository

    Lanas, Vanessa

    2014-02-01

    Larger scale microbial fuel cells (MFCs) require compact architectures to efficiently treat wastewater. We examined how anode-brush diameter, number of anodes, and electrode spacing affected the performance of the MFCs operated in fed-batch and continuous flow mode. All anodes were initially tested with the brush core set at the same distance from the cathode. In fed-batch mode, the configuration with three larger brushes (25 mm diameter) produced 80% more power (1240 mW m-2) than reactors with eight smaller brushes (8 mm) (690 mW m-2). The higher power production by the larger brushes was due to more negative and stable anode potentials than the smaller brushes. The same general result was obtained in continuous flow operation, although power densities were reduced. However, by moving the center of the smaller brushes closer to the cathode (from 16.5 to 8 mm), power substantially increased from 690 to 1030 mW m-2 in fed batch mode. In continuous flow mode, power increased from 280 to 1020 mW m-2, resulting in more power production from the smaller brushes than the larger brushes (540 mW m-2). These results show that multi-electrode MFCs can be optimized by selecting smaller anodes, placed as close as possible to the cathode. © 2013 Elsevier B.V. All rights reserved.

  11. Large size biogas-fed Solid Oxide Fuel Cell power plants with carbon dioxide management: Technical and economic optimization

    Science.gov (United States)

    Curletti, F.; Gandiglio, M.; Lanzini, A.; Santarelli, M.; Maréchal, F.

    2015-10-01

    This article investigates the techno-economic performance of large integrated biogas Solid Oxide Fuel Cell (SOFC) power plants. Both atmospheric and pressurized operation is analysed with CO2 vented or captured. The SOFC module produces a constant electrical power of 1 MWe. Sensitivity analysis and multi-objective optimization are the mathematical tools used to investigate the effects of Fuel Utilization (FU), SOFC operating temperature and pressure on the plant energy and economic performances. FU is the design variable that most affects the plant performance. Pressurized SOFC with hybridization with a gas turbine provides a notable boost in electrical efficiency. For most of the proposed plant configurations, the electrical efficiency ranges in the interval 50-62% (LHV biogas) when a trade-off of between energy and economic performances is applied based on Pareto charts obtained from multi-objective plant optimization. The hybrid SOFC is potentially able to reach an efficiency above 70% when FU is 90%. Carbon capture entails a penalty of more 10 percentage points in pressurized configurations mainly due to the extra energy burdens of captured CO2 pressurization and oxygen production and for the separate and different handling of the anode and cathode exhausts and power recovery from them.

  12. Size matter!

    DEFF Research Database (Denmark)

    Hansen, Pelle Guldborg; Jespersen, Andreas Maaløe; Skov, Laurits Rhoden

    2015-01-01

    Objectives We examined how a reduction in plate size would affect the amount of food waste from leftovers in a field experiment at a standing lunch for 220 CEOs. Methods A standing lunch for 220 CEOs in the Danish Opera House was arranged to feature two identical buffets with plates of two differ...

  13. Going beyond 20 μm-sized channels for studying red blood cell phase separation in microfluidic bifurcations.

    Science.gov (United States)

    Roman, Sophie; Merlo, Adlan; Duru, Paul; Risso, Frédéric; Lorthois, Sylvie

    2016-05-01

    Despite the development of microfluidics, experimental challenges are considerable for achieving a quantitative study of phase separation, i.e., the non-proportional distribution of Red Blood Cells (RBCs) and suspending fluid, in microfluidic bifurcations with channels smaller than 20 μm. Yet, a basic understanding of phase separation in such small vessels is needed for understanding the coupling between microvascular network architecture and dynamics at larger scale. Here, we present the experimental methodologies and measurement techniques developed for that purpose for RBC concentrations (tube hematocrits) ranging between 2% and 20%. The maximal RBC velocity profile is directly measured by a temporal cross-correlation technique which enables to capture the RBC slip velocity at walls with high resolution, highlighting two different regimes (flat and more blunted ones) as a function of RBC confinement. The tube hematocrit is independently measured by a photometric technique. The RBC and suspending fluid flow rates are then deduced assuming the velocity profile of a Newtonian fluid with no slip at walls for the latter. The accuracy of this combination of techniques is demonstrated by comparison with reference measurements and verification of RBC and suspending fluid mass conservation at individual bifurcations. The present methodologies are much more accurate, with less than 15% relative errors, than the ones used in previous in vivo experiments. Their potential for studying steady state phase separation is demonstrated, highlighting an unexpected decrease of phase separation with increasing hematocrit in symmetrical, but not asymmetrical, bifurcations and providing new reference data in regimes where in vitro results were previously lacking. PMID:27190568

  14. 3′ UTR-Dependent, miR-92-Mediated Restriction of Tis21 Expression Maintains Asymmetric Neural Stem Cell Division to Ensure Proper Neocortex Size

    Directory of Open Access Journals (Sweden)

    Ji-Feng Fei

    2014-04-01

    Full Text Available Mammalian neocortex size primarily reflects the number and mode of divisions of neural stem and progenitor cells. Cortical stem cells (apical progenitors switching from symmetric divisions, which expand their population, to asymmetric divisions, which generate downstream neuronal progenitors (basal progenitors, start expressing Tis21, a so-called antiproliferative/prodifferentiative gene. Tis21 encodes a small (17.5 kDa, functionally poorly characterized protein and a relatively large (2 kb, highly conserved 3′ UTR. Here, we show that mice lacking the Tis21 3′ UTR develop a microcephalic neocortex with fewer neurons, notably in the upper layers. This reflects a progressive decrease in basal progenitors, which in turn is due to a fraction of apical progenitors prematurely switching from asymmetric self-renewing to symmetric self-consuming divisions. This switch is caused by the markedly increased Tis21 protein level resulting from lack of microRNA-, notably miR-92-, dependent restriction of Tis21 expression. Our data show that a premature onset of consumptive neural stem cell divisions can lead to microcephaly.

  15. Sizing Stack and Battery of a Fuel Cell Hybrid Distribution Truck Dimensionnement pile et batterie d’un camion hybride à pile à combustible de distribution

    Directory of Open Access Journals (Sweden)

    Tazelaar E.

    2012-08-01

    Full Text Available An existing fuel cell hybrid distribution truck, built for demonstration purposes, is used as a case study to investigate the effect of stack (kW and battery (kW, kWh sizes on the hydrogen consumption of the vehicle. Three driving cycles, the NEDC for Low Power vehicles, CSC and JE05 cycle, define the driving requirements for the vehicle. The Equivalent Consumption Minimization Strategy (ECMS is used for determining the control setpoint for the fuel cell and battery system. It closely approximates the global minimum in fuel consumption, set by Dynamic Programming (DP. Using DP the sizing problem can be solved but ECMS can also be implemented real-time. For the considered vehicle and hardware, all three driving cycles result in optimal sizes for the fuel cell stack of approximately three times the average drive power demand. This demonstrates that sizing the fuel cell stack the average or maximum power demand is not necessarily optimal with respect to a minimum fuel consumption. The battery is sized to deliver the difference between specified stack power and the peak power in the total power demand. The sizing of the battery is dominated by its power handling capabilities. Therefore, a higher maximum C-rate leads to a lower battery weight which in turn leads to a lower hydrogen consumption. The energy storage capacity of the battery only becomes an issue for C-rates over 30. Compared to a Range Extender (RE configuration, where the stack size is comparable to the average power demand and the stack is operated on a constant power level, optimal stack and battery sizes with ECMS as EnergyManagement Strategy significantly reduce the fuel consumption. Compared to a RE strategy, ECMS makes much better use of the combined power available from the fuel cell stack and the battery, resulting in a lower fuel consumption but also enabling a lower battery weight which consequently leads to improved payload capabilities. Un camion hybride, utilisant une pile

  16. Development of Micro-sized Microbial Fuel Cells as Ultra-Low Power Generators Using Nano-engineered Materials and Sustainable Designs

    KAUST Repository

    Mink, Justine E.

    2013-12-01

    Many of the most pressing global challenges today and in the future center around the scarcity of sustainable energy and water sources. The innovative microbial fuel cell (MFC) technology addresses both as it utilizes bacteria to convert wastewaters into electricity. Advancing this technology requires a better understanding of the optimal materials, designs and conditions involved. The micro-sized MFC was recently developed to serve this need by providing a rapid testing device requiring only a fraction of the materials. Further, development of micro-liter scale MFCs has expanded into potential applications such as remote and self-sustained power sources as well as on-chip energy generators. By using microfabrication, the fabrication and assembly of microsized MFCs is potentially inexpensive and mass produced. The objective of the work within this dissertation was to explore and optimize the micro-sized MFC to maximize power and current generation towards the goal of a usable and application-oriented device. Micro-sized MFCs were examined and developed using four parameters/themes considered most important in producing a high power generating, yet usable device: Anode- The use of nano-engineered carbon nanomaterials, carbon nanotubes and graphene, as anode as well as testing semiconductor industry standard anode contact area materials for enhanced current production. 5 Cathode- The introduction of a membrane-less air cathode to eliminate the need for continuous chemical refills and making the entire device mobile. Reactor design- The testing of four different reactor designs (1-75 μLs) with various features intended to increase sustainability, cost-effectiveness, and usability of the microsized MFC. Fuels- The utilization of real-world fuels, such as industrial wastewaters and saliva, to power micro-sized MFCs. The micro-sized MFC can be tailored to fit a variety of applications by varying these parameters. The device with the highest power production here was

  17. Testosterone replacement alters the cell size in visceral fat but not in subcutaneous fat in hypogonadal aged male rats as a late-onset hypogonadism animal model

    Directory of Open Access Journals (Sweden)

    Abdelhamed A

    2015-03-01

    Full Text Available Amr Abdelhamed,1,2 Shin-ichi Hisasue,1 Masato Shirai,3 Kazuhito Matsushita,1 Yoshiaki Wakumoto,1 Akira Tsujimura,1 Taiji Tsukamoto,4 Shigeo Horie1 1Department of Urology, Juntendo University, Graduate School of Medicine, Tokyo, Japan; 2Department of Dermatology, Venereology and Andrology, Sohag University, Graduate School of Medicine, Sohag, Egypt; 3Department of Urology, Juntendo University Urayasu Hospital, Urayasu, Japan; 4Department of Urology, School of Medicine, Sapporo Medical University, Sapporo, Japan Background: Patients with late-onset hypogonadism (LOH benefit from testosterone replacement by improvement in the parameters of the metabolic syndrome, but fat cell morphology in these patients is still unclear. This study aims to determine the effect of testosterone replacement on the morphology of fat cells in subcutaneous and visceral adipose tissue and on erectile function in hypogonadal aged male rats as a model of LOH. Methods: Ten male Sprague-Dawley rats aged 20–22 months were randomly allocated to two groups, ie, aged male controls (control group, n=5 and aged males treated with testosterone replacement therapy (TRT group, n=5. Testosterone enanthate 25 mg was injected subcutaneously every 2 weeks for 6 weeks. At 6 weeks, the intracavernous pressure (ICP and mean arterial blood pressure (MAP ratio was assessed. Visceral and subcutaneous adipose tissue specimens were collected and analyzed using Image-J software. Results: Body weight at 2, 4, and 6 weeks after TRT was 800.0±35.4 g, 767.5±46.3 g, and 780±40.4 g, respectively (not statistically significant. The ICP/MAP ratio was 0.341±0.015 in the TRT group and 0.274±0.049 in the control group (not statistically significant. The median subcutaneous fat cell size was 4.85×103 (range 0.85–12.53×103 µm2 in the control group and 4.93×103 (range 6.42–19.7×103 µm2 in the TRT group (not statistically significant. In contrast, median visceral fat cell size was significantly

  18. Metal nano-particles sizing by thermal annealing for the enhancement of surface plasmon effects in thin-film solar cells application

    Science.gov (United States)

    Hsieh, Li-Zen; Chau, Yuan-Fong Chou; Lim, Chee Ming; Lin, Mo-Hua; Huang, Hung Ji; Lin, Chun-Ting; Muhammad Nur Syafi'ie, Md Idris

    2016-07-01

    The optical properties and surface plasmon effects of different thickness of silver film grown on a silicon substrate were experimentally and numerically investigated. By modifying the film thickness and the annealing temperature, the size of metal nanoparticles (MNPs) can be manipulated. The reflectance of silver film deposited onto silicon wafers were adjusted by controlling the film thickness and annealing temperature. The experimental results show the MNPs grew larger with thinner deposition of silver film, and this has a correlation to the reflectance. We found that the thermal annealing temperature affects the optical properties of the MNPs, and this enhances the E-field intensity on the MNPs, and contributes to the improvement in the conversion efficiency of solar cells. This paper describes our attempts to develop a simple method that can replace the previously reported processes of lithography and thermal vacuum evaporation of the silver film and MNPs preparation.

  19. Impact of size of region-of-interest on differentiation of renal cell carcinoma and renal cysts on multi-phase CT: Preliminary findings

    Energy Technology Data Exchange (ETDEWEB)

    Rosenkrantz, Andrew B., E-mail: Andrew.Rosenkrantz@nyumc.org [Department of Radiology, NYU Langone Medical Center, 550 First Avenue, New York, NY 10016 (United States); Matza, Brent W.; Portnoy, Elie [Department of Radiology, NYU Langone Medical Center, 550 First Avenue, New York, NY 10016 (United States); Melamed, Jonathan [Department of Pathology, NYU Langone Medical Center, 550 First Avenue, New York, NY 10016 (United States); Taneja, Samir S. [Division of Urologic Oncology, Department of Urology, NYU Langone Medical Center, 550 First Avenue, New York, NY 10016 (United States); Wehrli, Natasha E. [Department of Radiology, NYU Langone Medical Center, 550 First Avenue, New York, NY 10016 (United States)

    2014-02-15

    Introduction: To assess impact of size of regions-of-interest (ROI) on differentiation of RCC and renal cysts using multi-phase CT, with focus on differentiating papillary RCC (pRCC) and cysts given known hypovascularity of pRCC. Methods: 99 renal lesions (23 pRCC, 47 clear-cell RCC, 7 chromophobe RCC, 22 cysts) underwent multi-phase CT. Subjective presence of visual enhancement was recorded for each lesion. Whole-lesion (WL) ROIs, and small (≤5 mm{sup 2}), medium (average size of small and large ROIs), and large (half of lesion diameter) peripherally located partial-lesion (PL) ROIs, were placed on non-contrast and nephrographic phases. Impact of ROI size in separating cysts from all RCC and from pRCC based on increased attenuation between phases was assessed using ROC analysis. Results: Visual enhancement was perceived in 96% of ccRCC, 61% of pRCC, and 9% of cysts. AUCs for separating all RCC and cysts for WL-ROI and small, medium, and large PL-ROIs were 91%, 96%, 91% and 93%, and among lesions without visible enhancement were 60%, 79%, 67% and 67%. AUCs for separating pRCC and cysts for WL-ROI and small, medium, and large PL-ROIs were 78%, 92%, 82% and 84%, and among lesions without visible enhancement were 64%, 88%, 69% and 69%. Conclusion: Small PL-ROIs had higher accuracy than WL-ROI or other PL-ROIs in separating RCC from cysts, with greater impact in differentiating pRCC from cysts and differentiating lesions without visible enhancement. Thus, when evaluating renal lesions using multi-phase CT, we suggest placing small peripheral ROIs for highest accuracy in distinguishing renal malignancy and benign cysts.

  20. Impact of size of region-of-interest on differentiation of renal cell carcinoma and renal cysts on multi-phase CT: Preliminary findings

    International Nuclear Information System (INIS)

    Introduction: To assess impact of size of regions-of-interest (ROI) on differentiation of RCC and renal cysts using multi-phase CT, with focus on differentiating papillary RCC (pRCC) and cysts given known hypovascularity of pRCC. Methods: 99 renal lesions (23 pRCC, 47 clear-cell RCC, 7 chromophobe RCC, 22 cysts) underwent multi-phase CT. Subjective presence of visual enhancement was recorded for each lesion. Whole-lesion (WL) ROIs, and small (≤5 mm2), medium (average size of small and large ROIs), and large (half of lesion diameter) peripherally located partial-lesion (PL) ROIs, were placed on non-contrast and nephrographic phases. Impact of ROI size in separating cysts from all RCC and from pRCC based on increased attenuation between phases was assessed using ROC analysis. Results: Visual enhancement was perceived in 96% of ccRCC, 61% of pRCC, and 9% of cysts. AUCs for separating all RCC and cysts for WL-ROI and small, medium, and large PL-ROIs were 91%, 96%, 91% and 93%, and among lesions without visible enhancement were 60%, 79%, 67% and 67%. AUCs for separating pRCC and cysts for WL-ROI and small, medium, and large PL-ROIs were 78%, 92%, 82% and 84%, and among lesions without visible enhancement were 64%, 88%, 69% and 69%. Conclusion: Small PL-ROIs had higher accuracy than WL-ROI or other PL-ROIs in separating RCC from cysts, with greater impact in differentiating pRCC from cysts and differentiating lesions without visible enhancement. Thus, when evaluating renal lesions using multi-phase CT, we suggest placing small peripheral ROIs for highest accuracy in distinguishing renal malignancy and benign cysts

  1. Nanocrystal Size-Dependent Efficiency of Quantum Dot Sensitized Solar Cells in the Strongly Coupled CdSe Nanocrystals/TiO2 System.

    Science.gov (United States)

    Yun, Hyeong Jin; Paik, Taejong; Diroll, Benjamin; Edley, Michael E; Baxter, Jason B; Murray, Christopher B

    2016-06-15

    Light absorption and electron injection are important criteria determining solar energy conversion efficiency. In this research, monodisperse CdSe quantum dots (QDs) are synthesized with five different diameters, and the size-dependent solar energy conversion efficiency of CdSe quantum dot sensitized solar cell (QDSSCs) is investigated by employing the atomic inorganic ligand, S(2-). Absorbance measurements and transmission electron microscopy show that the diameters of the uniform CdSe QDs are 2.5, 3.2, 4.2, 6.4, and 7.8 nm. Larger CdSe QDs generate a larger amount of charge under the irradiation of long wavelength photons, as verified by the absorbance results and the measurements of the external quantum efficiencies. However, the smaller QDs exhibit faster electron injection kinetics from CdSe QDs to TiO2 because of the high energy level of CBCdSe, as verified by time-resolved photoluminescence and internal quantum efficiency results. Importantly, the S(2-) ligand significantly enhances the electronic coupling between the CdSe QDs and TiO2, yielding an enhancement of the charge transfer rate at the interfacial region. As a result, the S(2-) ligand helps improve the new size-dependent solar energy conversion efficiency, showing best performance with 4.2-nm CdSe QDs, whereas conventional ligand, mercaptopropionic acid, does not show any differences in efficiency according to the size of the CdSe QDs. The findings reported herein suggest that the atomic inorganic ligand reinforces the influence of quantum confinement on the solar energy conversion efficiency of QDSSCs. PMID:27224958

  2. AMINO ACID SYNTHESIS IN PHOTO-SYNTHESIZING SPINACH CELLS. EFFECTS OF AMMONIA ON POOL SIZES AND RATES OF LABELING FROM {sup 14}CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, Peder Olesen; Cornwell, Karen L.; Gee, Sherry L.; Bassham, James A.

    1980-10-01

    Isolated cells from leaves of Spinacea oleracea have been maintained in a state capable of high rates of photosynthetic CO{sub 2} fixation for more than 60 h. The incorporation of {sup 14}CO{sub 2} under saturating CO{sub 2} conditions into carbohydrates, carboxylic acids, and amino acids, and the effect of ammonia on this incorporation have been studied. Total incorporation, specific radioactivity and pool size have been determined as a function of time for most of the protein amino acids and for {gamma}-aminobutyric acid. the measurements of specific activities and of the approaches to {sup 14}C "saturation" of some amino acids indicate the presence and relative sizes of metabolically active and passive pools of these amino acids. Added ammonia decreased carbon fixation into carbohydrates and increased fixation into carboxylic acids and amino acids. Different amino acids were, however, affected in different and highly specific ways. Ammonia caused large stimulatory effects in incorporation of {sup 14}C into glutamine (a factor of 16), No effect or slight decreases were seen in glycine, serine, phenylalanine, and tyrosine labeling, In.the case of glutamate, {sup 14}C-labeling decreased, but specific activity increased. The production of labeled {gamma}-aminobutyric acid was virtually stopped by ammonia. The results indicate that added ammonia stimulates the reactions mediated by pyruvate kinase and phosphoenolpyruvate carboxylase, as seen with other plant systems. The data on the effects of added ammonia on total labeling, pool sizes, and specific activities of several amino acids provides a number of indications about the intracellular sites of principal synthesis from carbon skeletons of these amino acids and the selective nature of effects of increased intracellular ammonia concentration on such synthesis.

  3. Design of super-elastic biodegradable scaffolds with longitudinally oriented microchannels and optimization of the channel size for Schwann cell migration

    Directory of Open Access Journals (Sweden)

    Koichiro Uto, Takanari Muroya, Michio Okamoto, Hiroyuki Tanaka, Tsuyoshi Murase, Mitsuhiro Ebara and Takao Aoyagi

    2012-01-01

    Full Text Available We newly designed super-elastic biodegradable scaffolds with longitudinally oriented microchannels for repair and regeneration of peripheral nerve defects. Four-armed poly(ε-caprolactone-co-D,L-lactides (P(CL-co-DLLAs were synthesized by ring-opening copolymerization of CL and DLLA from terminal hydroxyl groups of pentaerythritol, and acryloyl chloride was then reacted with the ends of the chains. The end-functionalized P(CL-co-DLLA was crosslinked in a cylindrical mold in the presence of longitudinally oriented silica fibers as the templates, which were later dissolved by hydrofluoric acid. The elastic moduli of the crosslinked P(CL-co-DLLAs were controlled between 10−1 and 102 MPa at 37 °C, depending on the composition. The scaffolds could be elongated to 700% of their original size without fracture or damage ('super-elasticity'. Scanning electron microscopy images revealed that well-defined and highly aligned multiple channels consistent with the mold design were produced in the scaffolds. Owing to their elastic nature, the microchannels in the scaffolds did not collapse when they were bent to 90°. To evaluate the effect of the channel diameter on Schwann cell migration, microchannels were also fabricated in transparent poly(dimethylsiloxane, allowing observation of cell migration. The migration speed increased with channel size, but the Young's modulus of the scaffold decreased as the channel diameter increased. These findings may serve as the basis for designing tissue-engineering scaffolds for nerve regeneration and investigating the effects of the geometrical and dimensional properties on axonal outgrowth.

  4. A solvent approach to the size-controllable synthesis of ultrafine Pt catalysts for methanol oxidation in direct methanol fuel cells

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • An ethylene glycol-based approach for the synthesis of Pt/C catalysts with uniform Pt nanoparticles. • Superior catalytic activity of Pt/C catalysts synthesized at EG/water volume ratio of 1/1 for methanol oxidation reaction. • High performance of MEA for DMFC using Pt/C catalysts synthesized at EG/water volume ratio of 1/1 at anode. - Abstract: An ethylene glycol (EG)-based approach has been developed for the synthesis of Pt/C catalysts with uniform Pt nanoparticles. A number of characterization techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical measurements are used to characterize the as-prepared Pt catalysts. The well-dispersed Pt nanoparticles with average size of approximate 2 nm could be obtained in the EG/water mixture with volume ratio of 1/1, which display higher activity for methanol oxidation than that of the Pt/C products prepared at other EG/water volume ratios (0:1, 2:1, and 1:0). In particular, the performance of the Pt nanoparticles prepared at EG/water volume ratio of 1/1 in the membrane electrode assembly for direct methanol fuel cells has also been evaluated and benchmarked by commercial Pt/C catalysts. This study offers a vivid example to synthesize Pt nanoparticles with fine size and good catalytic activity by simply tuning the solvent ratio in colloidal chemistry methods

  5. Evaluation of osteogenic cell differentiation in response to bone morphogenetic protein or demineralized bone matrix in a critical sized defect model using GFP reporter mice.

    Science.gov (United States)

    Alaee, Farhang; Hong, Seung-Hyun; Dukas, Alex G; Pensak, Michael J; Rowe, David W; Lieberman, Jay R

    2014-09-01

    We evaluated the osteoprogenitor response to rhBMP-2 and DBM in a transgenic mouse critical sized defect. The mice expressed Col3.6GFPtopaz (a pre-osteoblastic marker), Col2.3GFPemerald (an osteoblastic marker) and α-smooth muscle actin (α-SMA-Cherry, a pericyte/myofibroblast marker). We assessed defect healing at various time points using radiographs, frozen, and conventional histologic analyses. GFP signal in regions of interest corresponding to the areas of new bone formation was quantified using a novel computer assisted algorithm. All defects treated with rhBMP-2 healed. In contrast, the majority of the defects in the DBM (27/30) and control (28/30) groups did not heal. Quantitation of pre-osteoblasts demonstrated a maximal response (% GFP + cells/TV) in the Col3.6GFPtopaz mice at day 7 (7.2% ± 6.0, p Col2.3GFP cells was seen at days 14 (8.04% ± 5.0) and 21 (8.31% ± 4.32), p < 0.05. In contrast, DBM and control groups showed a limited osteogenic response at all time points. In conclusion, we demonstrated that the BMP and DBM induce vastly different osteogenic responses which should influence their clinical application as bone graft substitutes. PMID:24888702

  6. Brain scaling in mammalian evolution as a consequence of concerted and mosaic changes in numbers of neurons and average neuronal cell size

    Directory of Open Access Journals (Sweden)

    Suzana eHerculano-Houzel

    2014-08-01

    Full Text Available Enough species have now been subject to systematic quantitative analysis of the relationship between the morphology and cellular composition of their brain that patterns begin to emerge and shed light on the evolutionary path that led to mammalian brain diversity. Based on an analysis of the shared and clade-specific characteristics of 41 modern mammalian species in 6 clades, and in light of the phylogenetic relationships among them, here we propose that ancestral mammal brains were composed and scaled in their cellular composition like modern afrotherian and glire brains: with an addition of neurons that is accompanied by a decrease in neuronal density and very little modification in glial cell density, implying a significant increase in average neuronal cell size in larger brains, and the allocation of approximately 2 neurons in the cerebral cortex and 8 neurons in the cerebellum for every neuron allocated to the rest of brain. We also propose that in some clades the scaling of different brain structures has diverged away from the common ancestral layout through clade-specific (or clade-defining changes in how average neuronal cell mass relates to numbers of neurons in each structure, and how numbers of neurons are differentially allocated to each structure relative to the number of neurons in the rest of brain. Thus, the evolutionary expansion of mammalian brains has involved both concerted and mosaic patterns of scaling across structures. This is, to our knowledge, the first mechanistic model that explains the generation of brains large and small in mammalian evolution, and it opens up new horizons for seeking the cellular pathways and genes involved in brain evolution.

  7. DNA double-strand breaks in mammalian cells exposed to γ-rays and very heavy ions. Fragment-size distributions determined by pulsed-field gel electrophoresis

    International Nuclear Information System (INIS)

    The spatial distribution of DNA double-strand breaks (DSB) was assessed after treatment of mammalian cells (V79) with densely ionizing radiation. Cells were exposed to beams of heavy charged particles (calcium ions: 6.9 MeV/u, 2.1.103 keV/μm; uranium ions: 9.0 MeV/u, 1.4.104 keV/μm) at the linear accelerator UNILAC of GSI, Darmstadt. DNA was isolated in agarose plugs and subjected to pulsed-field gel electrophoresis under conditions that separated DNA fragments of size 50 kbp to 5 Mbp. The measured fragment distributions were compared to those obtained after γ-irradiation and were analyzed by means of a convolution and a deconvolution technique. In contrast to the finding for γ-radiation, the distributions produced by heavy ions do not correspond to the random breakage model. Their marked overdispersion and the observed excess of short fragments reflect spatial clustering of DSB that extends over large regions of the DNA, up to several mega base pairs (Mbp). At fluences of 0.75 and 1.5/μm2, calcium ions produce nearly the same shape of fragment spectrum, merely with a difference in the amount of DNA entering the gel; this suggests that the DNA is fragmented by individual calcium ions. At a fluence of 0.8/μm2 uranium ions produce a profile that is shifted to smaller fragment sizes in comparison to the profile obtained at a fluence of 0.4/μm2; this suggests cumulative action of two separate ions in the formation of fragments. These observations are not consistent with the expectation that the uranium ions, with their much larger LET, should be more likely to produce single particle action than the calcium ions. However, a consideration of the greater lateral extension of the tracks of the faster uranium ions explains the observed differences; it suggests that the DNA is closely coiled so that even DNA locations several Mbp apart are usually not separated by less than 0.1 or 0.2 μm. (orig.)

  8. DNA double-strand breaks in mammalian cells exposed to gamma-rays and very heavy ions. Fragment-size distributions determined by pulsed-field gel electrophoresis.

    Science.gov (United States)

    Kraxenberger, F; Weber, K J; Friedl, A A; Eckardt-Schupp, F; Flentje, M; Quicken, P; Kellerer, A M

    1998-07-01

    The spatial distribution of DNA double-strand breaks (DSB) was assessed after treatment of mammalian cells (V79) with densely ionizing radiation. Cells were exposed to beams of heavy charged particles (calcium ions: 6.9 MeV/u, 2.1.10(3) keV/microm; uranium ions: 9.0 MeV/u, 1.4.10(4) keV/microm) at the linear accelerator UNILAC of GSI, Darmstadt. DNA was isolated in agarose plugs and subjected to pulsed-field gel electrophoresis under conditions that separated DNA fragments of size 50 kbp to 5 Mbp. The measured fragment distributions were compared to those obtained after gamma-irradiation and were analyzed by means of a convolution and a deconvolution technique. In contrast to the finding for gamma-radiation, the distributions produced by heavy ions do not correspond to the random breakage model. Their marked overdispersion and the observed excess of short fragments reflect spatial clustering of DSB that extends over large regions of the DNA, up to several mega base pairs (Mbp). At fluences of 0.75 and 1.5/microm2, calcium ions produce nearly the same shape of fragment spectrum, merely with a difference in the amount of DNA entering the gel; this suggests that the DNA is fragmented by individual calcium ions. At a fluence of 0.8/microm2 uranium ions produce a profile that is shifted to smaller fragment sizes in comparison to the profile obtained at a fluence of 0.4/microm2; this suggests cumulative action of two separate ions in the formation of fragments. These observations are not consistent with the expectation that the uranium ions, with their much larger LET, should be more likely to produce single particle action than the calcium ions. However, a consideration of the greater lateral extension of the tracks of the faster uranium ions explains the observed differences; it suggests that the DNA is closely coiled so that even DNA locations several Mbp apart are usually not separated by less than 0. 1 or 0.2 microm. PMID:9728743

  9. L-DOPA decarboxylase mRNA expression is associated with tumor stage and size in head and neck squamous cell carcinoma: a retrospective cohort study

    International Nuclear Information System (INIS)

    Head and neck squamous cell carcinoma (HNSCC) represents one of the most commonly diagnosed malignancies worldwide. The DDC gene encodes L-DOPA decarboxylase, an enzyme catalyzing the decarboxylation of L-DOPA to dopamine. We have recently shown that DDC mRNA is a significant predictor of patients’ prognosis in colorectal adenocarcinoma and prostate cancer. The aim of the current study was to analyze the DDC mRNA expression in HNSCC patients. 53 malignant tumors were resected from the larynx, pharynx, tongue, buccal mucosa, parotid glands, and nasal cavity, as well as from 34 adjacent non-cancerous tissues of HNSCC patients, and were homogenized. Total RNA was isolated and converted into first-strand cDNA. An ultrasensitive real-time PCR method based on the SYBR Green chemistry was used for DDC mRNA quantification in head and neck tissue specimens. Relative quantification was performed using the comparative Ct (2-ddCt) method. DDC mRNA levels were lower in squamous cell carcinomas (SCCs) of the larynx and tongue than in adjacent non-cancerous tissue specimens. Furthermore, low DDC mRNA expression was noticed in laryngeal and tongue tumors of advanced TNM stage or bigger size, compared to early-stage or smaller tumors, respectively. No statistically significant differences were observed between SCCs resected from pharynx, buccal mucosa, or nasal cavity, and their normal counterparts. This is the first study examining the DDC mRNA expression in HNSCC. According to our results, DDC mRNA expression may constitute a potential prognostic biomarker in tongue and/or larynx SCCs, which principally represent the overwhelming majority of HNSCC cases

  10. Small size ion pumps

    International Nuclear Information System (INIS)

    This paper describes some designs of the two versions ion pumps and their range operation for various magnetic fields. The first version is made with different cell size in the anode element and titanium cathode operating in magnetic field from 600 to 650 Gs and the second version with the same anode element but differential Ti/Ta cathode working in magnetic field above 1200 Gs

  11. Dental pulp-derived stromal cells exhibit a higher osteogenic potency than bone marrow-derived stromal cells in vitro and in a porcine critical-size bone defect model

    Directory of Open Access Journals (Sweden)

    Jensen Jonas

    2016-01-01

    Full Text Available Introduction: The osteogenic differentiation of bone marrow-derived mesenchymal stromal cells (BMSCs was compared with that of dental pulp-derived stromal cells (DPSCs in vitro and in a pig calvaria critical-size bone defect model. Methods: BMSCs and DPSCs were extracted from the tibia bone marrow and the molar teeth of each pig, respectively. BMSCs and DPSCs were cultured in monolayer and on a three-dimensional (3D polycaprolactone (PCL – hyaluronic acid – tricalcium phosphate (HT-PCL scaffold. Population doubling (PD, alkaline phosphatase (ALP activity, and calcium deposition were measured in monolayer. In the 3D culture ALP activity, DNA content, and calcium deposition were evaluated. Six non-penetrating critical-size defects were made in each calvarium of 14 pigs. Three paired sub-studies were conducted: (1 empty defects vs. HT-PCL scaffolds; (2 PCL scaffolds vs. HT-PCL scaffolds; and (3 autologous BMSCs on HT-PCL scaffolds vs. autologous DPSCs on HT-PCL scaffolds. The observation time was five weeks. Bone volume fractions (BV/TV were assessed with micro-computed tomography (μCT and histomorphometry. Results and discussion: The results from the in vitro study revealed a higher ALP activity and calcium deposition of the DPSC cultures compared with BMSC cultures. Significantly more bone was present in the HT-PCL group than in both the pure PCL scaffold group and the empty defect group in vivo. DPSCs generated more bone than BMSCs when seeded on HT-PCL. In conclusion, DPSCs exhibited a higher osteogenic potential compared with BMSCs both in vitro and in vivo, making it a potential cell source for future bone tissue engineering.

  12. Dental pulp-derived stromal cells exhibit a higher osteogenic potency than bone marrow-derived stromal cells in vitro and in a porcine critical-size bone defect model

    Science.gov (United States)

    Jensen, Jonas; Tvedesøe, Claus; Rölfing, Jan Hendrik Duedal; Foldager, Casper Bindzus; Lysdahl, Helle; Kraft, David Christian Evar; Chen, Muwan; Baas, Jorgen; Le, Dang Quang Svend; Bünger, Cody Eric

    2016-01-01

    Introduction: The osteogenic differentiation of bone marrow-derived mesenchymal stromal cells (BMSCs) was compared with that of dental pulp-derived stromal cells (DPSCs) in vitro and in a pig calvaria critical-size bone defect model. Methods: BMSCs and DPSCs were extracted from the tibia bone marrow and the molar teeth of each pig, respectively. BMSCs and DPSCs were cultured in monolayer and on a three-dimensional (3D) polycaprolactone (PCL) – hyaluronic acid – tricalcium phosphate (HT-PCL) scaffold. Population doubling (PD), alkaline phosphatase (ALP) activity, and calcium deposition were measured in monolayer. In the 3D culture ALP activity, DNA content, and calcium deposition were evaluated. Six non-penetrating critical-size defects were made in each calvarium of 14 pigs. Three paired sub-studies were conducted: (1) empty defects vs. HT-PCL scaffolds; (2) PCL scaffolds vs. HT-PCL scaffolds; and (3) autologous BMSCs on HT-PCL scaffolds vs. autologous DPSCs on HT-PCL scaffolds. The observation time was five weeks. Bone volume fractions (BV/TV) were assessed with micro-computed tomography (μCT) and histomorphometry. Results and discussion: The results from the in vitro study revealed a higher ALP activity and calcium deposition of the DPSC cultures compared with BMSC cultures. Significantly more bone was present in the HT-PCL group than in both the pure PCL scaffold group and the empty defect group in vivo. DPSCs generated more bone than BMSCs when seeded on HT-PCL. In conclusion, DPSCs exhibited a higher osteogenic potential compared with BMSCs both in vitro and in vivo, making it a potential cell source for future bone tissue engineering. PMID:27163105

  13. Particle size and conductivity study of P-type copper (I) iodide (CuI) thin film for solid state dye sensitized solar cells

    International Nuclear Information System (INIS)

    Full text: Copper Iodide based dye-sensitized solar cells (DSSC) has been reported either deliver small photocurrents or highly unstable. In this research, by added in a small amount of Tetra-methyl-ethylene-diamine (TMED) into CuI sol-gel (CuI in acetonitrile), performance of electrical properties and optical properties of CuI based DSSC have been studied. Particles size and conductivity of CuI solution were measured when addition of TMED to the sol at 0.05 M concentrations. Spin-coating technique has been explored to prepare nano-crystalline CuI films at room temperature. The film was examined for their surface morphology, optical and electrical properties by field emission scanning electron microscope (FESEM), ultraviolet visible spectroscopy (UV-Vis), Photoluminescence (PL) and current-voltage (I-V) measurement respectively. The results were then compared with CuI sol-gel which prepared by dissolving CuI powder with acetonitrile only. It showed some improvement to the CuI-based DSSC by incorporation of a small quantity of TMED in the solution of precursor. (author)

  14. In vivo venous assessment of red blood cell aggregate sizes in diabetic patients with a quantitative cellular ultrasound imaging method: proof of concept.

    Directory of Open Access Journals (Sweden)

    Julien Tripette

    Full Text Available Diabetic patients present higher level of red blood cell (RBC aggregation contributing to the development of vascular complications. While it has been suggested that this hematology/rheology parameter could bring additional prognostic information for the management of those patients, RBC aggregation screening is not included as a clinical practice. Most medical centers are not equipped to measure properly this parameter, although sedimentation tests can bring some indication. Here, we aimed at evaluating the feasibility of using ultrasound to assess in-vivo hyper-aggregation in type 2 diabetic patients.Seventeen diabetic patients and 15 control subjects underwent ultrasound measurements of RBC aggregation in both cephalic and great saphenous veins. Non-invasive in-vivo ultrasound measurements were performed using a newly developed cellular imaging technique, the structure factor size and attenuation estimator (SFSAE. Comparisons with an ex-vivo gold standard rheometry technique were done, along with measurements of pro-aggregating plasma molecule concentrations.In-vivo RBC aggregation was significantly higher in diabetic patients compared with controls for cephalic vein measurements, while a trend (p = 0.055 was noticed in the great saphenous vein. SFSAE measurements were correlated with gold standard in-vitro measures, fibrinogen and C-reactive protein plasma concentrations.RBC aggregation can be measured in-vivo in diabetic patients using ultrasound. Prospective studies are needed to determine whether the SFSAE method could help clinicians in the early management of vascular complications in this patient population.

  15. Recommendations of the International Council for Standardization in Haematology for Ethylenediaminetetraacetic Acid Anticoagulation of Blood for Blood Cell Counting and Sizing. International Council for Standardization in Haematology: Expert Panel on Cytometry.

    Science.gov (United States)

    1993-10-01

    Of the three ethylenediaminetetraacetic acid (EDTA) salts used for anticoagulation of blood specimens for hematologic testing, potassium salts are the most readily soluble. Tripotassium EDTA is dispensed as a liquid and thus causes a slight dilution of the specimen. This salt also has been shown to affect the red blood cell size more at increased concentrations and on storage than the dipotassium salt. Therefore, dipotassium EDTA is recommended as the anticoagulant of choice in specimen collection for blood cell counting and sizing. The amount of dipotassium EDTA used is 1.5-2.2 mg (3.7-5.4 mumol) per milliliter of blood. PMID:8213631

  16. Size-dependent cytotoxicity of Fe3O4 nanoparticles induced by biphasic regulation of oxidative stress in different human hepatoma cells

    Directory of Open Access Journals (Sweden)

    Xie Y

    2016-07-01

    Full Text Available Yuexia Xie,1,2,* Dejun Liu,3,* Chenlei Cai,1,* Xiaojing Chen,1 Yan Zhou,1 Liangliang Wu,1 Yongwei Sun,3 Huili Dai,1,2 Xianming Kong,1,2 Peifeng Liu1,2 1Central Laboratory, 2State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, 3Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: The application of Fe3O4 nanoparticles (NPs has made great progress in the diagnosis of disease and in the drug delivery system for cancer therapy, but the relative mecha­nisms of potential toxicity induced by Fe3O4 have not kept pace with its development in the application, which has hampered its further clinical application. In this article, we used two kinds of human hepatoma cell lines, SK-Hep-1 and Hep3B, to investigate the cytotoxic effects and the involved mechanisms of small Fe3O4 NPs with different diameters (6 nm, 9 nm, and 14 nm. Results showed that the size of NPs effectively influences the cytotoxicity of hepatoma cells: 6 nm Fe3O4 NPs exhibited negligible cytotoxicity and 9 nm Fe3O4 NPs affected cytotoxicity via cellular mitochondrial dysfunction and by inducing necrosis mediated through the mitochondria-dependent intracellular reactive oxygen species generation. Meanwhile, 14 nm Fe3O4 NPs induced cytotoxicity by impairing the integrity of plasma membrane and promoting massive lactate dehydrogenase leakage. These results explain the detailed mechanism of different diameters of small Fe3O4 NPs-induced cytotoxicity. We anticipate that this study will provide different insights into the cytotoxicity mechanism of Fe3O4 NPs, so as to make them safer to use in clinical application. Keywords: hepatoma cells, nanoparticles, cytotoxicity, mechanism, oxidative stress

  17. Clinical outcomes of stereotactic body radiotherapy for stage I non-small cell lung cancer using different doses depending on tumor size

    International Nuclear Information System (INIS)

    The treatment schedules for stereotactic body radiotherapy (SBRT) for lung cancer vary from institution to institution. Several reports have indicated that stage IB patients had worse outcomes than stage IA patients when the same dose was used. We evaluated the clinical outcomes of SBRT for stage I non-small cell lung cancer (NSCLC) treated with different doses depending on tumor diameter. Between February 2004 and November 2008, 124 patients with stage I NSCLC underwent SBRT. Total doses of 44, 48, and 52 Gy were administered for tumors with a longest diameter of less than 1.5 cm, 1.5-3 cm, and larger than 3 cm, respectively. All doses were given in 4 fractions. For all 124 patients, overall survival was 71%, cause-specific survival was 87%, progression-free survival was 60%, and local control was 80%, at 3 years. The 3-year overall survival was 79% for 85 stage IA patients treated with 48 Gy and 56% for 37 stage IB patients treated with 52 Gy (p = 0.05). At 3 years, cause-specific survival was 91% for the former group and 79% for the latter (p = 0.18), and progression-free survival was 62% versus 54% (p = 0.30). The 3-year local control rate was 81% versus 74% (p = 0.35). The cumulative incidence of grade 2 or 3 radiation pneumonitis was 11% in stage IA patients and 30% in stage IB patients (p = 0.02). There was no difference in local control between stage IA and IB tumors despite the difference in tumor size. The benefit of increasing the SBRT dose for larger tumors should be investigated further

  18. Mesenchymal Stromal Cell-Derived Factors Promote Tissue Repair in a Small-for-Size Ischemic Liver Model but Do Not Protect against Early Effects of Ischemia and Reperfusion Injury

    NARCIS (Netherlands)

    S.M.G. Fouraschen (Suomi M. G.); J.H. Wolf (Joshua H.); L.J.W. van der Laan (Luc); P.E. de Ruiter (Petra E.); W. Hancock; J.P. Van Kooten (Job P.); M.M.A. Verstegen (Monique); K.M. Olthoff (Kim); J. de Jonge (Jeroen)

    2015-01-01

    textabstractLoss of liver mass and ischemia/reperfusion injury (IRI) are major contributors to postresectional liver failure and small-for-size syndrome. Mesenchymal stromal cell-(MSC-) secreted factors are described to stimulate regeneration after partial hepatectomy. This study investigates if liv

  19. Expansion of IgG+ B-cells during mitogen stimulation for memory B-cell ELISpot analysis is influenced by size and composition of the B-cell pool

    NARCIS (Netherlands)

    Scholzen, A.; Nahrendorf, W.; Langhorne, J.; Sauerwein, R.W.

    2014-01-01

    The memory B-cell (MBC) ELISpot assay is the main technique used to measure antigen-specific MBCs as a readout of humoral immune memory. This assay relies on the ability of MBCs to differentiate into antibody-secreting cells (ASC) upon polyclonal stimulation. The total number of IgG+ ASCs generated

  20. The first systematic analysis of 3D rapid prototyped poly(ε-caprolactone) scaffolds manufactured through BioCell printing: the effect of pore size and geometry on compressive mechanical behaviour and in vitro hMSC viability

    International Nuclear Information System (INIS)

    Novel additive manufacturing processes are increasingly recognized as ideal techniques to produce 3D biodegradable structures with optimal pore size and spatial distribution, providing an adequate mechanical support for tissue regeneration while shaping in-growing tissues. With regard to the mechanical and biological performances of 3D scaffolds, pore size and geometry play a crucial role. In this study, a novel integrated automated system for the production and in vitro culture of 3D constructs, known as BioCell Printing, was used only to manufacture poly(ε-caprolactone) scaffolds for tissue engineering; the influence of pore size and shape on their mechanical and biological performances was investigated. Imposing a single lay-down pattern of 0°/90° and varying the filament distance, it was possible to produce scaffolds with square interconnected pores with channel sizes falling in the range of 245–433 µm, porosity 49–57% and a constant road width. Three different lay-down patterns were also adopted (0°/90°, 0°/60/120° and 0°/45°/90°/135°), thus resulting in scaffolds with quadrangular, triangular and complex internal geometries, respectively. Mechanical compression tests revealed a decrease of scaffold stiffness with the increasing porosity and number of deposition angles (from 0°/90° to 0°/45°/90°/135°). Results from biological analysis, carried out using human mesenchymal stem cells, suggest a strong influence of pore size and geometry on cell viability. On the other hand, after 21 days of in vitro static culture, it was not possible to detect any significant variation in terms of cell morphology promoted by scaffold topology. As a first systematic analysis, the obtained results clearly demonstrate the potential of the BioCell Printing process to produce 3D scaffolds with reproducible well organized architectures and tailored mechanical properties. (paper)

  1. On the Relationship between Pollen Size and Genome Size

    Directory of Open Access Journals (Sweden)

    Charles A. Knight

    2010-01-01

    Full Text Available Here we test whether genome size is a predictor of pollen size. If it were, inferences of ancient genome size would be possible using the abundant paleo-palynolgical record. We performed regression analyses across 464 species of pollen width and genome size. We found a significant positive trend. However, regression analysis using phylogentically independent contrasts did not support the correlated evolution of these traits. Instead, a large split between angiosperms and gymnosperms for both pollen width and genome size was revealed. Sister taxa were not more likely to show a positive contrast when compared to deeper nodes. However, significantly more congeneric species had a positive trend than expected by chance. These results may reflect the strong selection pressure for pollen to be small. Also, because pollen grains are not metabolically active when measured, their biology is different than other cells which have been shown to be strongly related to genome size, such as guard cells. Our findings contrast with previously published research. It was our hope that pollen size could be used as a proxy for inferring the genome size of ancient species. However, our results suggest pollen is not a good candidate for such endeavors.

  2. PDE type-4 inhibition increases L-type Ca(2+) currents, action potential firing, and quantal size of exocytosis in mouse chromaffin cells.

    Science.gov (United States)

    Marcantoni, A; Carabelli, V; Vandael, D H; Comunanza, V; Carbone, E

    2009-03-01

    We studied the effects of the cAMP-hydrolyzing enzyme phosphodiesterase type-4 (PDE4) on the L-type Ca(2+) channels (LTCCs) and Ca(2+)-dependent secretion in mouse chromaffin cells (MCCs). The selective PDE4 inhibitor rolipram (3 microM) had a specific potentiating action on Ca(2+) currents of MCCs (40% increase within 3 min). A similar effect was produced by the selective beta(1)-AR agonist denopamine (1 microM) and by the unselective PDEs inhibitor IBMX (100 microM). Rolipram and denopamine actions were selective for LTCCs, and the Ca(2+) current increase remained unchanged if the two compounds were applied simultaneously. This suggests that at rest, LTCCs in MCCs are down-regulated by the low levels of cAMP determined by PDE4 activity and that LTCCs can be up-regulated by either inhibiting PDE4 or activating beta(1)-AR. No other PDEs are likely involved in this specific action. PDE4 inhibition had also a marked effect on the spontaneous firing of resting MCCs and catecholamine secretion. Rolipram up-regulated the LTCCs contributing to the "pace-maker" current underlying action potential (AP) discharges and accelerated the firing rate, with no significant effects on AP waveform. Acceleration of AP firing was also induced by the LTCC-agonist Bay K (1 microM), while nifedipine (3 microM) reduced the firing frequency, suggesting that LTCCs and intracellular cAMP play a key role in setting the pace-maker current regulating MCCs excitability. Rolipram increased also the size of the ready-releasable pool and the quantal content of secretory vesicles without affecting their probability of release. Thus, rolipram acts on MCCs by up-regulating both exocytosis and AP firings. These two processes are effectively down-regulated by PDE4 at rest and can dramatically increase the quantity of released catecholamines when PDE4 is inhibited and/or cAMP is raised. PMID:18779976

  3. Expression of intercellular adhesion molecule-1 in rat heart with ischemia/reperfusion and limitation of infarct size by treatment with antibodies against cell adhesion molecules.

    OpenAIRE

    Yamazaki, T; Seko, Y; Tamatani, T; Miyasaka, M.; Yagita, H; Okumura, K.; R. Nagai; Yazaki, Y

    1993-01-01

    To elucidate the mechanism(s) of myocardial reperfusion injury, we investigated the roles of cell adhesion molecules on both leukocytes and vascular endothelial cells in the reperfused myocardia. We found that within 2 hours after reperfusion leukocytes began to infiltrate into the rat myocardia subjected to 30 minutes of ischemia and clarified, for the first time, that the expression of intercellular adhesion molecule-1 was enhanced on the capillary and venous endothelial cells from 8 to 96 ...

  4. Mesenchymal Stromal Cell-Derived Factors Promote Tissue Repair in a Small-for-Size Ischemic Liver Model but Do Not Protect against Early Effects of Ischemia and Reperfusion Injury

    OpenAIRE

    Fouraschen, Suomi M. G.; Wolf, Joshua H.; van der Laan, Luc J W; de Ruiter, Petra E.; Hancock, Wayne W.; van Kooten, Job P.; Verstegen, Monique M. A.; Olthoff, Kim M.; Jeroen de Jonge

    2015-01-01

    Loss of liver mass and ischemia/reperfusion injury (IRI) are major contributors to postresectional liver failure and small-for-size syndrome. Mesenchymal stromal cell- (MSC-) secreted factors are described to stimulate regeneration after partial hepatectomy. This study investigates if liver-derived MSC-secreted factors also promote liver regeneration after resection in the presence of IRI. C57BL/6 mice underwent IRI of 70% of their liver mass, alone or combined with 50% partial hepatectom...

  5. Nano-biolistics: a method of biolistic transfection of cells and tissues using a gene gun with novel nanometer-sized projectiles

    Directory of Open Access Journals (Sweden)

    Lummis Sarah CR

    2011-06-01

    Full Text Available Abstract Background Biolistic transfection is proving an increasingly popular method of incorporating DNA or RNA into cells that are difficult to transfect using traditional methods. The technique routinely uses 'microparticles', which are ~1 μm diameter projectiles, fired into tissues using pressurised gas. These microparticles are efficient at delivering DNA into cells, but cannot efficiently transfect small cells and may cause significant tissue damage, thus limiting their potential usefulness. Here we describe the use of 40 nm diameter projectiles - nanoparticles - in biolistic transfections to determine if they are a suitable alternative to microparticles. Results Examination of transfection efficiencies in HEK293 cells, using a range of conditions including different DNA concentrations and different preparation procedures, reveals similar behaviour of microparticles and nanoparticles. The use of nanoparticles, however, resulted in ~30% fewer damaged HEK293 cells following transfection. Biolistic transfection of mouse ear tissue revealed similar depth penetration for the two types of particles, and also showed that 20% in microparticle-transfected samples. Visualising details of small cellular structures was also considerably enhanced when using nanoparticles. Conclusions We conclude that nanoparticles are as efficient for biolistic transfection as microparticles, and are more appropriate for use in small cells, when examining cellular structures and/or where tissue damage is a problem.

  6. Upgrading of the Gray Laboratory soft X ray microprobe with V79 survival measurements following irradiation of one or all cells with a Ck X ray beam of different size

    International Nuclear Information System (INIS)

    The X ray microprobe developed at the Gray Laboratory was originally designed to produce carbon K X rays (278 eV) by electron bombardment and focus them to a few hundred nanometers spot by using a circular diffraction grating with increasing line density (zone plate). The very fine focus achieved (K X rays (photoelectron range -1 entrance dose averaged over a typical V79 cell) and to evaluate the possibility of using higher energy photons (AlK of 1.48 keV). The efficiency of the microprobe system has been tested by assessing the clonogenic potential of V79 cells irradiated with CK X ray beams of different sizes (5 and 0.25 μm radius) and investigating the relevance of the spatial distribution of cells for the bystander effect. (author)

  7. Mesenchymal Stromal Cell-Derived Factors Promote Tissue Repair in a Small-for-Size Ischemic Liver Model but Do Not Protect against Early Effects of Ischemia and Reperfusion Injury

    Directory of Open Access Journals (Sweden)

    Suomi M. G. Fouraschen

    2015-01-01

    Full Text Available Loss of liver mass and ischemia/reperfusion injury (IRI are major contributors to postresectional liver failure and small-for-size syndrome. Mesenchymal stromal cell- (MSC- secreted factors are described to stimulate regeneration after partial hepatectomy. This study investigates if liver-derived MSC-secreted factors also promote liver regeneration after resection in the presence of IRI. C57BL/6 mice underwent IRI of 70% of their liver mass, alone or combined with 50% partial hepatectomy (PH. Mice were treated with MSC-conditioned medium (MSC-CM or unconditioned medium (UM and sacrificed after 6 or 24 hours (IRI group or after 48 hours (IRI + PH group. Blood and liver tissue were analyzed for tissue injury, hepatocyte proliferation, and gene expression. In the IRI alone model, serum ALT and AST levels, hepatic tissue damage, and inflammatory cytokine gene expression showed no significant differences between both treatment groups. In the IRI + PH model, significant reduction in hepatic tissue damage as well as a significant increase in hepatocyte proliferation was observed after MSC-CM treatment. Conclusion. Mesenchymal stromal cell-derived factors promote tissue regeneration of small-for-size livers exposed to ischemic conditions but do not protect against early ischemia and reperfusion injury itself. MSC-derived factors therefore represent a promising treatment strategy for small-for-size syndrome and postresectional liver failure.

  8. Reconstruction and analysis of fuel cell gas diffusion layers using fiber spacing rather than pore size data: Questioned validity of widely-used porosity-based thermal conductivity models

    Science.gov (United States)

    Sadeghifar, Hamidreza

    2016-03-01

    Porosity and pore size data have long been used for reconstructing (two directional) fibrous materials. The present study is aimed to explain the overlooked fact that pore size parameter, bundling several other geometric parameters together, cannot be directly used for the reconstruction and geometrical modeling of gas diffusion layers (GDLs) of fuel cells. Instead, it has to be converted to fiber spacing, for which purpose it is a useful parameter. A technical approach is presented on how to reach fiber spacing from pore size (diameter) data. The reason why GDLs with the same porosity, fiber diameter and angle, but with unequal fiber spacing, may have different properties is also explained by providing physical evidence. The present study clearly demonstrates that the traditional notion that fibrous materials with lower porosity have higher thermal conductivity does not necessary hold. In addition, it is shown that GDLs with the same porosity and the same pore size may have different fiber spacing and thus, distinct properties. It is found that the thermal conductivity models based solely upon porosity can be off by several hundred percent and must be either discarded or used over the narrow range of conditions under which they have been formulated.

  9. Effective improvement of interface modified strontium titanate based solid oxide fuel cell anodes by infiltration with nano-sized palladium and gadolinium-doped cerium oxide

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain; Høgh, Jens Valdemar Thorvald; Zhang, Wei; Blennow Tullmar, Peter; Bonanos, Nikolaos; Boukamp, Bernard A.

    2013-01-01

    The development of low temperature solid oxide fuel cell (SOFC) anodes by infiltration of Pd/Gd-doped cerium oxide (CGO) electrocatalysts in Nb-doped SrTiO3 (STN) backbones has been investigated. Modification of the electrode/electrolyte interface by thin layer of spin-coated CGO (400-500 nm) con...

  10. The Impact of Tumor Size on Outcomes After Stereotactic Body Radiation Therapy for Medically Inoperable Early-Stage Non-Small Cell Lung Cancer

    International Nuclear Information System (INIS)

    Purpose: Stereotactic body radiation therapy for medically inoperable early-stage non-small cell lung cancer (NSCLC) offers excellent control rates. Most published series deal mainly with small (usually 3 in tumor volume) but are associated with more nonlocal failures as well as poorer survival. These observations suggest these patients may benefit from more extensive staging or consideration of adjuvant therapy

  11. Analysing the effect of crystal size and structure in highly efficient CH3NH3PbI3 perovskite solar cells by spatially resolved photo- and electroluminescence imaging

    Science.gov (United States)

    Mastroianni, S.; Heinz, F. D.; Im, J.-H.; Veurman, W.; Padilla, M.; Schubert, M. C.; Würfel, U.; Grätzel, M.; Park, N.-G.; Hinsch, A.

    2015-11-01

    CH3NH3PbI3 perovskite solar cells with a mesoporous TiO2 layer and spiro-MeOTAD as a hole transport layer (HTL) with three different CH3NH3I concentrations (0.032 M, 0.044 M and 0.063 M) were investigated. Strong variations in crystal size and morphology resulting in diversified cell efficiencies (9.2%, 16.9% and 12.3%, respectively) were observed. The physical origin of this behaviour was analysed by detailed characterization combining current-voltage curves with photo- and electroluminescence (PL and EL) imaging as well as light beam induced current measurements (LBIC). It was found that the most efficient cell shows the highest luminescence and the least efficient cell is most strongly limited by non-radiative recombination. Crystal size, morphology and distribution in the capping layer and in the porous scaffold strongly affect the non-radiative recombination. Moreover, the very non-uniform crystal structure with multiple facets, as evidenced by SEM images of the 0.032 M device, suggests the creation of a large number of grain boundaries and crystal dislocations. These defects give rise to increased trap-assisted non-radiative recombination as is confirmed by high-resolution μ-PL images. The different imaging techniques used in this study prove to be well-suited to spatially investigate and thus correlate the crystal morphology of the perovskite layer with the electrical and radiative properties of the solar cells and thus with their performance.CH3NH3PbI3 perovskite solar cells with a mesoporous TiO2 layer and spiro-MeOTAD as a hole transport layer (HTL) with three different CH3NH3I concentrations (0.032 M, 0.044 M and 0.063 M) were investigated. Strong variations in crystal size and morphology resulting in diversified cell efficiencies (9.2%, 16.9% and 12.3%, respectively) were observed. The physical origin of this behaviour was analysed by detailed characterization combining current-voltage curves with photo- and electroluminescence (PL and EL) imaging as

  12. Striatins as plaque molecules of zonulae adhaerentes in simple epithelia, of tessellate junctions in stratified epithelia, of cardiac composite junctions and of various size classes of lateral adherens junctions in cultures of epithelia- and carcinoma-derived cells.

    Science.gov (United States)

    Franke, Werner W; Rickelt, Steffen; Zimbelmann, Ralf; Dörflinger, Yvette; Kuhn, Caecilia; Frey, Norbert; Heid, Hans; Rosin-Arbesfeld, Rina

    2015-03-01

    Proteins of the striatin family (striatins 1-4; sizes ranging from 90 to 110 kDa on SDS-polyacrylamide gel electrophoresis) are highly homologous in their amino acid sequences but can differ in their cell-type-specific gene expression patterns and biological functions. In various cell types, we have found one, two or three polypeptides of this evolutionarily old and nearly ubiquitous family of proteins known to serve as scaffold proteins for diverse protein complexes. Light and electron microscopic immunolocalization methods have revealed striatins in mammalian cell-cell adherens junctions (AJs). In simple epithelia, we have localized striatins as constitutive components of the plaques of the subapical zonulae adhaerentes of cells, including intestinal, glandular, ductal and urothelial cells and hepatocytes. Striatins colocalize with E-cadherin or E-N-cadherin heterodimers and with the plaque proteins α- and β-catenin, p120 and p0071. In some epithelia and carcinomas and in cultured cells derived therefrom, striatins are also seen in lateral AJs. In stratified epithelia and in corresponding squamous cell carcinomas, striatins can be found in plaques of some forms of tessellate junctions. Moreover, striatins are major plaque proteins of composite junctions (CJs; areae compositae) in the intercalated disks connecting cardiomyocytes, colocalizing with other CJ molecules, including plectin and ankyrin-G. We discuss the "multimodulator" scaffold roles of striatins in the initiation and regulation of the formation of various complex particles and structures. We propose that striatins are included in the diagnostic candidate list of proteins that, in the CJs of human hearts, can occur in mutated forms in the pathogeneses of hereditary cardiomyopathies, as seen in some types of genetically determined heart damage in boxer dogs. PMID:25501894

  13. To assess the reparative ability of differentiated mesenchymal stem cells in a rat critical size bone repair defect model using high frequency co-registered photoacoustic/ultrasound imaging and micro computed tomography

    Science.gov (United States)

    Zafar, Haroon; Gaynard, Sean; O'Flatharta, Cathal; Doroshenkova, Tatiana; Devine, Declan; Sharif, Faisal; Barry, Frank; Hayes, Jessica; Murphy, Mary; Leahy, Martin J.

    2016-03-01

    Stem cell based treatments hold great potential and promise to address many unmet clinical needs. The importance of non-invasive imaging techniques to monitor transplanted stem cells qualitatively and quantitatively is crucial. The objective of this study was to create a critical size bone defect in the rat femur and then assess the ability of the differentiated mesenchymal stem cells (MSCs) to repair the defect using high frequency co-registered photoacoustic(PA)/ultrasound(US) imaging and micro computed tomography (μCT) over an 8 week period. Combined PA and US imaging was performed using 256 elements, 21 MHz frequency linear-array transducer combined with multichannel collecting system. In vivo 3D PA and US images of the defect bone in the rat femur were acquired after 4 and 8 weeks of the surgery. 3D co-registered structural such as microvasculature and the functional images such as total concentration of haemoglobin (HbT) and the haemoglobin oxygen saturation (sO2) were obtained using PA and US imaging. Bone formation was assessed after 4 and 8 weeks of the surgery by μCT. High frequency linear-array based coregistered PA/US imaging has been found promising in terms of non-invasiveness, sensitivity, adaptability, high spatial and temporal resolution at sufficient depths for the assessment of the reparative ability of MSCs in a rat critical size bone repair defect model.

  14. Equilibrium size distribution of rouleaux

    Energy Technology Data Exchange (ETDEWEB)

    Perelson, A.S. (Los Alamos National Lab., NM); Wiegel, F.W.

    1982-02-01

    Rouleaux are formed by the aggregation of red blood cells in the presence of macromolecules that bridge the membranes of adherent erythrocytes. We compute the size and degree of branching of rouleaux for macroscopic systems in thermal equilibrium in the absence of fluid flow. Using techniques from statistical mechanics, analytical expressions are derived for (a) the average number of rouleaux consisting of n cells and having m branch points; (b) the average number of cells per rouleau; (c) the average number of branch points per rouleau; and (d) the number of rouleaux with n cells, n = 1, 2,..., in a system containing a total of N cells. We also present the results of numerical evaluations to establish the validity of asymptotic expressions that simplify our formal analytic results.

  15. Sizing up microbes

    OpenAIRE

    Viswanathan, V. K.

    2012-01-01

    The size range of life forms is dictated by basic principles of physics. Large microorganisms, with sizes approaching a millimeter, have compensating features that address the immutable laws of physics. For pathogens, size may impact a range of functions, such as adherence and immune evasion. We review several recent studies on factors impacting, and impacted by, the size of microorganisms.

  16. NOsize: 12px;">X Reduction Using an Electrochemical Cell with NOadsorbents

    DEFF Research Database (Denmark)

    Shao, Jing

    adsorption, surface diffusion, and transfer of NOx and O2 species at/near the triple phase boundary region, and the formation of intermediate NO2. Severe degradation was observed on both electrodes following long-term operation, caused by the corrosion of the Ag electrode covered by a nitrate melt, or...... associated with a profound change in the microstructure for the LSM/CGO electrode. Two different approaches to modify the electrochemical cell with NOx adsorbents, adding a Ba-Pt-Al2O3 adsorption layer on top of the electrode or impregnating of the BaO into the electrode, were studied on a LSM/CGO symmetric...... cell. A comprehensive comparison between the two approaches was provided based on systematic investigations, including conversion measurements, degradation tests, microstructure observations, and impedance characterization. It was found that both approaches significantly increased the activity and...

  17. Phylogenetic effective sample size

    OpenAIRE

    Bartoszek, Krzysztof

    2015-01-01

    In this paper I address the question - how large is a phylogenetic sample I propose a definition of a phylogenetic effective sample size for Brownian motion and Ornstein-Uhlenbeck processes - the regression effective sample size. I discuss how mutual information can be used to define an effective sample size in the non-normal process case and compare these two definitions to an already present concept of effective sample size (the mean effective sample size). Through a simulation study I find...

  18. Transgenerational Inheritance of Increased Fat Depot Size, Stem Cell Reprogramming, and Hepatic Steatosis Elicited by Prenatal Exposure to the Obesogen Tributyltin in Mice

    OpenAIRE

    Chamorro-García, Raquel; Sahu, Margaret; Abbey, Rachelle J; Laude, Jhyme; Pham, Nhieu; Blumberg, Bruce

    2013-01-01

    Background: We have previously shown that exposure to tributyltin (TBT) modulates critical steps of adipogenesis through RXR/PPARγ and that prenatal TBT exposure predisposes multipotent mesenchymal stem cells (MSCs) to become adipocytes by epigenetic imprinting into the memory of the MSC compartment. Objective: We tested whether the effects of prenatal TBT exposure were heritable in F2 and F3 generations. Methods: We exposed C57BL/6J female mice (F0) to DMSO vehicle, the pharmaceutical obesog...

  19. Allogeneic Transplantation of Periodontal Ligament-Derived Multipotent Mesenchymal Stromal Cell Sheets in Canine Critical-Size Supra-Alveolar Periodontal Defect Model

    OpenAIRE

    Tsumanuma, Yuka; Iwata, Takanori; Kinoshita, Atsuhiro; Washio, Kaoru; Yoshida, Toshiyuki; Yamada, Azusa; Takagi, Ryo; Yamato, Masayuki; Okano, Teruo; Izumi, Yuichi

    2016-01-01

    Abstract Periodontitis is a chronic inflammatory disease that induces the destruction of tooth-supporting tissues, followed by tooth loss. Although several approaches have been applied to periodontal regeneration, complete periodontal regeneration has not been accomplished. Tissue engineering using a combination of cells and scaffolds is considered to be a viable alternative strategy. We have shown that autologous transplantation of periodontal ligament-derived multipotent mesenchymal stromal...

  20. Allogeneic Transplantation of Periodontal Ligament-Derived Multipotent Mesenchymal Stromal Cell Sheets in Canine Critical-Size Supra-Alveolar Periodontal Defect Model.

    Science.gov (United States)

    Tsumanuma, Yuka; Iwata, Takanori; Kinoshita, Atsuhiro; Washio, Kaoru; Yoshida, Toshiyuki; Yamada, Azusa; Takagi, Ryo; Yamato, Masayuki; Okano, Teruo; Izumi, Yuichi

    2016-01-01

    Periodontitis is a chronic inflammatory disease that induces the destruction of tooth-supporting tissues, followed by tooth loss. Although several approaches have been applied to periodontal regeneration, complete periodontal regeneration has not been accomplished. Tissue engineering using a combination of cells and scaffolds is considered to be a viable alternative strategy. We have shown that autologous transplantation of periodontal ligament-derived multipotent mesenchymal stromal cell (PDL-MSC) sheets regenerates periodontal tissue in canine models. However, the indications for autologous cell transplantation in clinical situations are limited. Therefore, this study evaluated the safety and efficacy of allogeneic transplantation of PDL-MSC sheets using a canine horizontal periodontal defect model. Canine PDL-MSCs were labeled with enhanced green fluorescent protein (EGFP) and were cultured on temperature-responsive dishes. Three-layered cell sheets were transplanted around denuded root surfaces either autologously or allogeneically. A mixture of β-tricalcium phosphate and collagen gel was placed on the bone defects. Eight weeks after transplantation, dogs were euthanized and subjected to microcomputed tomography and histological analyses. RNA and DNA were extracted from the paraffin sections to verify the presence of EGFP at the transplantation site. Inflammatory markers from peripheral blood sera were quantified using an enzyme-linked immunosorbent assay. Periodontal regeneration was observed in both the autologous and the allogeneic transplantation groups. The allogeneic transplantation group showed particularly significant regeneration of newly formed cementum, which is critical for the periodontal regeneration. Serum levels of inflammatory markers from peripheral blood sera showed little difference between the autologous and allogeneic groups. EGFP amplicons were detectable in the paraffin sections of the allogeneic group. These results suggest that

  1. Receptive field center size decreases and firing properties mature in ON and OFF retinal ganglion cells after eye opening in the mouse

    OpenAIRE

    Koehler, Christopher L.; Akimov, Nikolay P.; Rentería, René C.

    2011-01-01

    Development of the mammalian visual system is not complete at birth but continues postnatally well after eye opening. Although numerous studies have revealed changes in the development of the thalamus and visual cortex during this time, less is known about the development of response properties of retinal ganglion cells (RGCs). Here, we mapped functional receptive fields of mouse RGCs using a Gaussian white noise checkerboard stimulus and a multielectrode array to record from retinas at eye o...

  2. The T-cell-mediated immune response and return rate of fledgling American kestrels are positively correlated with parental clutch size.

    OpenAIRE

    Tella, J L; Bortolotti, G. R.; Dawson, R.D.; Forero, M.G.

    2000-01-01

    Life-history theory predicts that parents face a trade-off between the number and viability of the progeny they produce. We found evidence for an apparent trade-off in a free-living population of American kestrels (Falco sparverius), as larger clutches produced more but lighter fledglings. However, while the body mass of fledglings has traditionally been used as a measure of survival prospect, offspring immunocompetence should also play an important role. We thus measured the T-cell-mediated ...

  3. The Inhibition Effect of Nano Size Alum-Borneol Emulsion to L-929 Cell%矾冰纳米乳对L-929细胞抑制作用的影响

    Institute of Scientific and Technical Information of China (English)

    刘丽芳; 伍参荣; 祁林

    2011-01-01

    目的:探讨矾冰纳来乳对L-929实验细胞增殖抑制作用.方法:采用细胞病变抑制法与MIT法,将试验药物稀释后加入培养4h贴壁的L- 929细胞中,37℃、5% CO2培养箱中观察24h、48h,同时设传统药物矾冰液和正常细胞对照,倒置显微镜下观察药物对细胞形态的影响,测定OD值比较药物对细胞生长的影响.结果:矾冰纳米乳对L - 929细胞的生长有随浓度增加其生长抑制率也增加的趋势,与矾冰液比较有统计学差异(P<0.05);矾冰纳米乳在同一浓度、同一时间内细胞增长抑制率低于矾冰液,差异有统计学意义(P0.05);倒置显微镜下观察细胞形态良好.结论:纳米矾冰乳对L - 929培养细胞无毒性作用,可以用于临床.%Objective:To study the proliferative inhibition effect of nano size Alum- Borneol emulsion to L- 929 cell.Methods: The cytopathogenic effect inhibition assay and MTT method were applied. The adherent L - 929 cell were added diluted drug and cultrued 24h, 48h in 7℃, 5% CO2 condition. The normal cell group and traditional Alum - Borneol liquid group were set as control. The effect of drugs to cell morphology and growth were detected by inverted microscope and OD assay respectively. Results: Compared with traditional Alum - Borneol liquid group, the nano size Alum - Bomeol emulsion could increase the proliferative inhibition effect on L - 929 cell with increasing of drug concentration ( P <0.05 ). The proliferative inhibition rate of nano size Alum - Borneol emulsion was lower than traditional Alum - Borneol liquid at same time and concentration( P <0.05 ). The proliferative inhibition rate of nano size Alum - Borneol emulsion was decreased with decreasing drug concentration and cultural time compared with normal control group( P <0.05 ).The morphology results show a good cell shape in inverted microscope. Conclusion: The nano size Alum - Borneol emulsion has no cytotoxicity to L- 929 cell and could applied to

  4. First-generation litter-size reduction following irradiation of spermatogonial stem cells in mice and its use in risk estimation

    International Nuclear Information System (INIS)

    Litter-size reduction (LSR) is a useful measure of part of the overall F1 radiation-induced damage. Extensive LSR data were obtained as a by-product of specific-locus experiments. Fourteen such experiments involving 158,490 F1 litters have been analyzed for the extent of LSR induced by x- or gamma-irradiation of spermatogonia. Litter sizes were compared between experimental and control groups at about 3 weeks after birth. At the high dose rate of 90 R/min, the LSRs showed a humped dose-response curve. There was a pronounced dose-rate effect, the mutational responses being much less at dose rates of 0.009 R/min and 0.001 R/min. It is estimated that if men were exposed to 1 R of radiation delivered at low linear energy transfer (low LET) and low dose rate, the number of deaths caused by induced dominant mutations among their children before late childhood would be about 19 per million live-born. This can be added to the earlier estimate of an approximately equal number of viable disorders in all body systems as based on dominant skeletal mutations. This gives a total estimate of induced dominant damage, but much of this addition represents death in very early embryonic life that would not be recognized in humans. The LSR data also permit the conclusion that only an extremely small proportion of serious radiation-induced genetic disorders among live-born humans would be expected to result from segmental aneuploidy

  5. One-step synthesis of small-sized and water-soluble NaREF4 upconversion nanoparticles for in vitro cell imaging and drug delivery.

    Science.gov (United States)

    Yang, Dongmei; Dai, Yunlu; Ma, Pingan; Kang, Xiaojiao; Cheng, Ziyong; Li, Chunxia; Lin, Jun

    2013-02-18

    Small (2-28 nm) NaREF(4) (rare earth (RE)=Nd-Lu, Y) nanoparticles (NPs) were prepared by an oil/water two-phase approach. Meanwhile, hydrophilic NPs can be obtained through a successful phase-transition process by introducing the amphiphilic surfactant sodium dodecylsulfate (SDS) into the same reaction system. Hollow-structured NaREF(4) (RE=Y, Yb, Lu) NPs can be fabricated in situ by electron-beam lithography on solid NPs. The MTT assay indicates that these hydrophilic NPs with hollow structures exhibit good biocompatibility. The as-prepared hollow-structured NPs can be used as anti-cancer drug carriers for drug storage/release investigations. Doxorubicin hydrochloride (DOX) was taken as model drug. The release of DOX from hollow α-NaLuF(4):20% Yb(3+), 2% Er(3+) exhibits a pH-sensitive release patterns. Confocal microscopy observations indicate that the NPs can be taken up by HeLa cells and show obvious anti-cancer efficacy. Furthermore, α-NaLuF(4):20% Yb(3+), 2% Er(3+) NPs show bright-red emission under IR excitation, making both the excitation and emission light fall within the "optical window" of biological tissues. The application of α-NaLuF(4):20% Yb(3+), 2% Er(3+) in the luminescence imaging of cells was also investigated, which shows a bright-red emission without background noise. PMID:23297246

  6. Measurement of bubble shape and size in bubbly flow structure for stagnant and pulsating liquid flow using an undivided electrochlorination cell and Telecentric Direct Image Method

    DEFF Research Database (Denmark)

    Andersen, Nikolaj; Stroe, Rodica-Elisabeta; Hedensted, Lau;

    2016-01-01

    This study presents the measurement of shape and diameter of bubbles in different regions of the bubbly flow structure at the cathode for stagnant and pulsating liquid flow in a single undivided electrochlorination cell. The cell is filled with a dilute sodium chloride electrolyte solution with a...... concentration of 30 g/L, and operated at a current density of 18.75 mA/cm2, and stagnant liquid flow, or pulsating liquid flow with a pulsation period of 3.5 s and rate of 760 mL/h. Measurements are conducted using a Telecentric Direct Image Method for acquiring images of the bubbles, and processing is done in...... MATLAB and NI Vision in LabVIEW to determine shape and diameter of the bubbles. Three bubble regions are observed; adherence, bubble diffusion and bulk region. For stagnant liquid flow the mean bubble diameter increases from 30 to 60 μm going from the adherence region to the bulk region, which is...

  7. The nature of excited states in dipolar donor/fullerene complexes for organic solar cells: evolution with the donor stack size.

    Science.gov (United States)

    Shen, Xingxing; Han, Guangchao; Yi, Yuanping

    2016-06-21

    Electronic delocalization at donor/acceptor (D/A) interfaces can play an important role in photocurrent generation for organic solar cells. Here, we have investigated the nature of local excited and interfacial charge transfer (CT) states in model complexes including one to four anti-parallel stacking dipolar donor (DTDCTB) molecules and one fullerene (C60) molecule by means of density functional theory (DFT) and time-dependent DFT (TDDFT). For all the donor-to-acceptor CT states, despite the number of DTDCTB molecules in the complexes, the hole is mainly localized on a single DTDCTB, and moves farther away from C60 for the energy higher level. However, the highest occupied molecular orbitals (HOMOs) and the excitonic states (EX) including the bright and dark EX are delocalized over the whole donor stacks in the complexes. This implies that the formation of ordered DTDCTB arrangements can substantially shorten the exciton diffusion process and facilitate ultrafast charge generation. Interestingly, owing to strong intermolecular Coulomb attraction, the donor-to-donor CT states are situated below the local excited states, but can approach the donor-to-acceptor CT states, indicating a weak role as charge traps. Our work would be helpful for understanding the electronic delocalization effects in organic solar cells. PMID:27241621

  8. Does Class Size Matter?

    Science.gov (United States)

    Ehrenberg, Ronald G.; Brewer, Dominic J.; Gamoran, Adam; Willms, J. Douglas

    2001-01-01

    Reports on the significance of class size to student learning. Includes an overview of class size in various countries, the importance of teacher adaptability, and the Asian paradox of large classes allied to high test scores. (MM)

  9. Strength training increases the size of the satellite cell pool in type I and II fibres of chronically painful trapezius muscle in females

    DEFF Research Database (Denmark)

    Mackey, Abigail; Andersen, Lars L; Frandsen, Ulrik;

    2011-01-01

    While strength training has been shown to be effective in mediating hypertrophy and reducing pain in trapezius myalgia, responses at the cellular level have not previously been studied. This study investigated the potential of strength training targeting the affected muscles (SST, n = 18) and...... general fitness training (GFT, n = 16) to augment the satellite cell (SC) and macrophage pools in the trapezius muscles of women diagnosed with trapezius myalgia. A group receiving general health information (REF, n = 8) served as a control. Muscle biopsies were collected from the trapezius muscles of the...... <0.0001), together with a significant correlation between the baseline number of SCs and the extent of hypertrophy (r = -0.669, P = 0.005). SST also resulted in a 74% enhancement of the trapezius macrophage content (P <0.01), accompanied by evidence for the presence of an increased number of actively...

  10. Size and Political Participation

    DEFF Research Database (Denmark)

    Lassen, David Dreyer; Serritzlew, Søren

    This paper uses a novel research design to re-examine the causal effect of jurisdiction size on political participation. Two waves of municipal consolidation in Denmark, in 1970 and in 2005, provide exogenous variation in jurisdiction size.......This paper uses a novel research design to re-examine the causal effect of jurisdiction size on political participation. Two waves of municipal consolidation in Denmark, in 1970 and in 2005, provide exogenous variation in jurisdiction size....

  11. Staurosporine augments EGF-mediated EMT in PMC42-LA cells through actin depolymerisation, focal contact size reduction and Snail1 induction – A model for cross-modulation

    Directory of Open Access Journals (Sweden)

    Thompson Erik W

    2009-07-01

    Full Text Available Abstract Background A feature of epithelial to mesenchymal transition (EMT relevant to tumour dissemination is the reorganization of actin cytoskeleton/focal contacts, influencing cellular ECM adherence and motility. This is coupled with the transcriptional repression of E-cadherin, often mediated by Snail1, Snail2 and Zeb1/δEF1. These genes, overexpressed in breast carcinomas, are known targets of growth factor-initiated pathways, however it is less clear how alterations in ECM attachment cross-modulate to regulate these pathways. EGF induces EMT in the breast cancer cell line PMC42-LA and the kinase inhibitor staurosporine (ST induces EMT in embryonic neural epithelial cells, with F-actin de-bundling and disruption of cell-cell adhesion, via inhibition of aPKC. Methods PMC42-LA cells were treated for 72 h with 10 ng/ml EGF, 40 nM ST, or both, and assessed for expression of E-cadherin repressor genes (Snail1, Snail2, Zeb1/δEF1 and EMT-related genes by QRT-PCR, multiplex tandem PCR (MT-PCR and immunofluorescence +/- cycloheximide. Actin and focal contacts (paxillin were visualized by confocal microscopy. A public database of human breast cancers was assessed for expression of Snail1 and Snail2 in relation to outcome. Results When PMC42-LA were treated with EGF, Snail2 was the principal E-cadherin repressor induced. With ST or ST+EGF this shifted to Snail1, with more extreme EMT and Zeb1/δEF1 induction seen with ST+EGF. ST reduced stress fibres and focal contact size rapidly and independently of gene transcription. Gene expression analysis by MT-PCR indicated that ST repressed many genes which were induced by EGF (EGFR, CAV1, CTGF, CYR61, CD44, S100A4 and induced genes which alter the actin cytoskeleton (NLF1, NLF2, EPHB4. Examination of the public database of breast cancers revealed tumours exhibiting higher Snail1 expression have an increased risk of disease-recurrence. This was not seen for Snail2, and Zeb1/δEF1 showed a reverse

  12. The relationship between sirtuin 1 (SIRT1 expression and tumor size, Proliferating Cell Nuclear Antigen (PCNA expression and histological grading in rat breast carcinoma induced by dimethylbenz(anthracene (DMBA

    Directory of Open Access Journals (Sweden)

    Novrita Padauleng Dewajani Purnomosari, Sri Herwiyanti Harjadi, Irianiwati, Sitarina Widyarini

    2014-08-01

    Full Text Available Controversy regarding the role of SIRT1 in pathology of cancers exists and is still under debate.SIRT1 could act as either a tumor supressor or tumor promotor. This study was conducted toevaluate the relationship between SIRT1 expression and tumor size, Proliferating Cell NuclearAntigen (PCNA expression and histological grading in rat breast carcinoma induced bydimethylbenz(áanthracene (DMBA. Thirty female Sprague Dawley rats were randomly allocatedinto three groups with 10 rats in each group. Group 1 as negative control was just fed thestandard food. Group 2 as vehicle control was fed the standard food and corn oil. Group 3 asinduction group was fed the standard food and induced with DMBA at dose of 20 mg/kg bodyweight (BW in corn oil twice a week for five weeks. All rats were palpated weekly to determinethe appearance, size and location of tumors. Sixteen weeks after DMBA induction rats weresacrified and histological preparations of the breast carcinoma tissue were then processed forSIRT1 and PCNA expression examination as well as histological grading. The result showed thatSIRT1 expression was significantly higher in breast carcinoma tissue compared to normal gland(26.12 vs 0.05; p = 0.004. SIRT1-positive was observed mostly in poor histological gradecarcinomas (56.2%, and it was not observed in good histological grade carcinomas. However,there was no significantly difference between SIRT1 and histological grading (p = 0.097; r =0.285. A significant correlation between SIRT1 expression and the tumor size (p =0.009; r=0.877, as well as PCNA expression (p =0.000; r =0.790 was observed. In conclusion, thereis relationship between SIRT1 expression and tumor size as well as PCNA expression in rat breastcarcinoma induced by DMBA.

  13. Nanoparticle size and combined toxicity of TiO2 and DSLS (surfactant) contribute to lysosomal responses in digestive cells of mussels exposed to TiO2 nanoparticles.

    Science.gov (United States)

    Jimeno-Romero, A; Oron, M; Cajaraville, M P; Soto, M; Marigómez, I

    2016-10-01

    The aim of this investigation was to understand the bioaccumulation, cell and tissue distribution and biological effects of disodium laureth sulfosuccinate (DSLS)-stabilised TiO2 nanoparticles (NPs) in marine mussels, Mytilus galloprovincialis. Mussels were exposed in vivo to 0.1, 1 and 10 mg Ti/L either as TiO2 NPs (60 and 180 nm) or bulk TiO2, as well as to DSLS alone. A significant Ti accumulation was observed in mussels exposed to TiO2 NPs, which were localised in endosomes, lysosomes and residual bodies of digestive cells, and in the lumen of digestive tubules, as demonstrated by ultrastructural observations and electron probe X-ray microanalysis. TiO2 NPs of 60 nm were internalised within digestive cell lysosomes to a higher extent than TiO2 NPs of 180 nm, as confirmed by the quantification of black silver deposits after autometallography. The latter were localised mainly forming large aggregates in the lumen of the gut. Consequently, lysosomal membrane stability (LMS) was significantly reduced upon exposure to both TiO2 NPs although more markedly after exposure to TiO2-60 NPs. Exposure to bulk TiO2 and to DSLS also affected the stability of the lysosomal membrane. Thus, effects on the lysosomal membrane depended on the nanoparticle size and on the combined biological effects of TiO2 and DSLS. PMID:27241615

  14. Sample Size Calculations

    OpenAIRE

    Noordzij, Marlies; Dekker, Friedo W.; Zoccali, Carmine; Jager, Kitty J.

    2011-01-01

    The sample size is the number of patients or other experimental units that need to be included in a study to answer the research question. Pre-study calculation of the sample size is important; if a sample size is too small, one will not be able to detect an effect, while a sample that is too large may be a waste of time and money. Methods to calculate the sample size are explained in statistical textbooks, but because there are many different formulas available, it can be difficult for inves...

  15. Mesenchymal stem cells promote liver regeneration and prolong survival in small-for-size liver grafts: involvement of C-Jun N-terminal kinase, cyclin D1, and NF-κB.

    Directory of Open Access Journals (Sweden)

    Weijie Wang

    Full Text Available BACKGROUND: The therapeutic potential of mesenchymal stem cells (MSCs has been highlighted recently for treatment of acute or chronic liver injury, by possibly differentiating into hepatocyte-like cells, reducing inflammation, and enhancing tissue repair. Despite recent progress, exact mechanisms of action are not clearly elucidated. In this study, we attempted to explore whether and how MSCs protected hepatocytes and stimulated allograft regeneration in small-for-size liver transplantation (SFSLT. METHODS: SFSLT model was established with a 30% partial liver transplantation (30PLT in rats. The differentiation potential and characteristics of bone marrow derived MSCs were explored in vitro. MSCs were infused transvenously immediately after graft implantation in therapy group. Expressions of apoptosis-, inflammatory-, anti-inflammatory-, and growth factor-related genes were measured by RT-PCR, activities of transcription factors AP-1 and NF-κB were analyzed by EMSA, and proliferative responses of the hepatic graft were evaluated by immunohistochemistry and western blot. RESULTS: MSCs were successfully induced into hepatocyte-like cells, osteoblasts and adipocytes in vitro. MSCs therapy could not only alleviate ischemia reperfusion injury and acute inflammation to promote liver regeneration, but also profoundly improve one week survival rate. It markedly up-regulated the mRNA expressions of HGF, Bcl-2, Bcl-XL, IL-6, IL-10, IP-10, and CXCR2, however, down-regulated TNF-α. Increased activities of AP-1 and NF-κB, as well as elevated expressions of p-c-Jun, cyclin D1, and proliferating cell nuclear antigen (PCNA, were also found in MSCs therapy group. CONCLUSION: These data suggest that MSCs therapy promotes hepatocyte proliferation and prolongs survival in SFSLT by reducing ischemia reperfusion injury and acute inflammation, and sustaining early increased expressions of c-Jun N-terminal Kinase, Cyclin D1, and NF-κB.

  16. Toxicity of chlorinated phenoxyacetic acid herbicides in the experimental eukaryotic model Saccharomyces cerevisiae: role of pH and of growth phase and size of the yeast cell population.

    Science.gov (United States)

    Cabral, M G; Viegas, C A; Teixeira, M C; Sá-Correia, I

    2003-04-01

    The inhibitory effect of the herbicides 2-methyl-4-chlorophenoxyacetic acid (MCPA) and 2,4-dichlorophenoxyacetic acid (2,4-D) in Saccharomyces cerevisiae growth is strongly dependent on medium pH (range 2.5-6.5). Consistent with the concept that the toxic form is the liposoluble undissociated form, at values close to their pK(a) (3.07 and 2.73, respectively) the toxicity is high, decreasing with the increase of external pH. In addition, the toxicity of identical concentrations of the undissociated acid form is pH independent, as observed with 2,4-dichlorophenol (2,4-DCP), an intermediate of 2,4-D degradation. Consequently, at pH values above 3.5 (approximately one unit higher than 2,4-D pK(a)), 2,4-DCP becomes more toxic than the original herbicide. A dose-dependent inhibition of growth kinetics and increased duration of growth latency is observed following sudden exposure of an unadapted yeast cell population to the presence of the herbicides. This contrasts with the effect of 2,4-DCP, which essentially affects growth kinetics. Experimental evidences suggest that the acid herbicides toxicity is not exclusively dependent on the liposolubility of the toxic form, as may essentially be the case of 2,4-DCP. An unadapted yeast cell population at the early stationary-phase of growth under nutrient limitation is significantly more resistant to short-term herbicide induced death than an exponential-phase population. Consequently, the duration of growth latency is reduced, as observed with the increase of the size of the herbicide stressed population. However, these physiological parameters have no significant effect either on growth kinetics, following growth resumption under herbicide stress, or on the growth curve of yeast cells previously adapted to the herbicides, indicating that their role is exerted at the level of cell adaptation. PMID:12586155

  17. Blood flow-metabolic relationships are dependent on tumour size in non-small cell lung cancer: a study using quantitative contrast-enhanced computer tomography and positron emission tomography

    International Nuclear Information System (INIS)

    The purpose of this study was to undertake dual assessment of tumour blood flow and glucose metabolism in non-small cell lung cancer (NSCLC) using contrast-enhanced computed tomography (CE-CT) and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in order to assess how the relationships between these parameters vary with tumour size and stage. Tumour blood flow and glucose metabolism were assessed in 18 NSCLCs using quantitative CE-CT and FDG-PET respectively. Contrast enhancement and FDG uptake were both normalised to injected dose and patient weight to yield correspondingly the standardised perfusion value (SPV) and standardised uptake value (SUV). Tumour area was measured from conventional CT images. The ratio of SUV to SVP and the metabolic-flow difference (SUV-SVP) correlated with tumour size (r=0.56, p=0.015 and r=0.60 and p=0.008 respectively). A metabolic-flow difference of greater than 4 was more common amongst tumours of stages III and IV (odds ratio 10.5; 95% confidence limits 0.24-32.1). A significant correlation between SUV and SPV was found only for tumours smaller than 4.5 cm2 (r=0.85, p=0.03). Blood flow-metabolic relationships are not consistent in NSCLC but depend upon tumour size and stage. Quantitative CE-CT as an adjunct to an FDG study undertaken using integrated PET-CT offers an efficient way to augment the assessment of tumour biology with possible future application as part of clinical care. (orig.)

  18. Determination of Sample Size

    OpenAIRE

    Naing, Nyi Nyi

    2003-01-01

    There is a particular importance of determining a basic minimum required ‘n’ size of the sample to recognize a particular measurement of a particular population. This article has highlighted the determination of an appropriate size to estimate population parameters.

  19. Nozzles: selection and sizing

    OpenAIRE

    Grisso, Robert D. (Robert Dwight), 1956-; Hipkins, Patricia A.; Askew, Shawn; Hipkins, Perry Lloyd, 1945-; McCall, David Scott

    2013-01-01

    Covers nozzle description, recommended use for common nozzle types, and orifice sizing for agricultural and turf sprayers. Proper selection of a nozzle type and size is essential for correct and accurate pesticide application. The nozzle is a major factor in determining the amount of spray applied to an area, uniformity of application, coverage obtained on the target surface, and amount of potential drift.

  20. Plant, cell, and molecular mechanisms of abscisic-acid regulation of stomatal apertures. A new mechanism for the regulation of stomatal-aperture size in intact leaves: Accumulation of mesophyll-derived sucrose in the guard-cell wall of Vicia faba L.

    Energy Technology Data Exchange (ETDEWEB)

    Lu, P.; Outlaw, W.H. Jr.; Smith, B.G.; Freed, G.A.

    1996-12-31

    At various times after pulse labeling Vicia faba L. leaflets with {sup 14}CO{sub 2}, whole-leaf pieces and rinsed epidermal peels were harvested and subsequently processed for histochemical analysis. Cells dissected from whole leaf retained apoplastic contents whereas those from rinsed peels contained only cytoplastic contents. Sucrose specific radioactivity peaked in palisade cells, 111 GBq{center_dot}mol{sup {minus}1}, at 20 min. In contrast, the {sup 14}C content and sucrose specific radioactivity were very low in guard cells for 20 min, implying little CO{sub 2} incorporation; both then peaked at 40 min. The guard-cell apoplast had a high maximum sucrose specific radioactivity and a high sucrose influx rate. These and other comparisons implied the presence of (a) multiple sucrose pools in mesophyll cells, (b) a localized mesophyll-apoplast region that exchanges with phloem and stomata, and (c) mesophyll-derived sucrose in guard-cell walls sufficient to diminish stomatal opening by {approximately} 4 {micro}m. Factors expected to enhance sucrose accumulation in guard-cell walls are (a) high transpiration rate, which closes stomata, and (b) high apoplastic sucrose concentration, which is elevated when mesophyll-sucrose efflux exceeds translocation. Therefore, multiple physiological factors are integrated in the attenuation of stomatal-aperture size by this previously unrecognized mechanism.

  1. Molecular mechanism of size control in development and human diseases

    Institute of Scientific and Technical Information of China (English)

    Xiaolong Yang; Tian Xu

    2011-01-01

    How multicellular organisms control their size is a fundamental question that fascinated generations of biologists.In the past 10 years, tremendous progress has been made toward our understanding of the molecular mechanism underlying size control. Original studies from Drosophila showed that in addition to extrinsic nutritional and hormonal cues, intrinsic mechanisms also play important roles in the control of organ size during development. Several novel signaling pathways such as insulin and Hippo-LATS signaling pathways have been identified that control organ size by regulating cell size and/or cell number through modulation of cell growth, cell division, and cell death. Later studies using mammalian cell and mouse models also demonstrated that the signaling pathways identified in flies are also conserved in mammals. Significantly, recent studies showed that dysregulation of size control plays important roles in the development of many human diseases sucha as cancer,diabetes,and hypertrophy.

  2. The equilibrium size distribution of rouleaux.

    OpenAIRE

    Perelson, A. S.; Wiegel, F.W.

    1982-01-01

    Rouleaux are formed by the aggregation of red blood cells in the presence of macromolecules that bridge the membranes of adherent erythrocytes. We compute the size and degree of branching of rouleaux for macroscopic systems in thermal equilibrium in the absence of fluid flow. Using techniques from statistical mechanics, analytical expressions are derived for (a) the average number of rouleaux consisting of n cells and having m branch points; (b) the average number of cells per rouleau; (c) th...

  3. Preparation of multi-coloured different sized fluorescent gold clusters from blue to NIR, structural analysis of the blue emitting Au7 cluster, and cell-imaging by the NIR gold cluster

    Science.gov (United States)

    Roy, Subhasish; Baral, Abhishek; Bhattacharjee, Rameswar; Jana, Batakrishna; Datta, Ayan; Ghosh, Surajit; Banerjee, Arindam

    2015-01-01

    Blue, green, orange-red, red and NIR emitting gold quantum clusters have been prepared in aqueous media by using a bioactive peptide glutathione (reduced) at physiological pH. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) analyses show that the core structure sizes of the five different gold clusters are Au7 (blue), Au16 (green), Au19 (orange-red), Au21 (red) and Au22 (NIR). The photo-stability and pH-stability of these quantum clusters have been measured, and these are photo-stable against continuous UV irradiation for a few hours. They also exhibit moderate to good pH-stability within the pH range of 5-12.5. A computational study reveals the organisation of gold atoms in the thiolate-protected blue quantum cluster and its several structural parameters, including the mode of interaction of ligand molecules with Au atoms in the Au7 cluster. Interestingly, it has been found that NIR emitting gold quantum cluster can easily be internalized into the adenocarcinomic human alveolar basal epithelial cell line (A549 cell line). Moreover, a MTT assay indicates that our NIR emitting gold quantum cluster show very low cytotoxicy to A549 cancer cells.Blue, green, orange-red, red and NIR emitting gold quantum clusters have been prepared in aqueous media by using a bioactive peptide glutathione (reduced) at physiological pH. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) analyses show that the core structure sizes of the five different gold clusters are Au7 (blue), Au16 (green), Au19 (orange-red), Au21 (red) and Au22 (NIR). The photo-stability and pH-stability of these quantum clusters have been measured, and these are photo-stable against continuous UV irradiation for a few hours. They also exhibit moderate to good pH-stability within the pH range of 5-12.5. A computational study reveals the organisation of gold atoms in the thiolate-protected blue quantum cluster and its several

  4. Sample size methodology

    CERN Document Server

    Desu, M M

    2012-01-01

    One of the most important problems in designing an experiment or a survey is sample size determination and this book presents the currently available methodology. It includes both random sampling from standard probability distributions and from finite populations. Also discussed is sample size determination for estimating parameters in a Bayesian setting by considering the posterior distribution of the parameter and specifying the necessary requirements. The determination of the sample size is considered for ranking and selection problems as well as for the design of clinical trials. Appropria

  5. The right size

    Energy Technology Data Exchange (ETDEWEB)

    Knowles, R. [Univ. of Southern California, Los Angeles, CA (United States)

    1996-10-01

    The right size, and notably the right size of a building, is relative. It is dependent upon the costs of construction and of maintenance. It is also proportional to the more illusory standards of livability and of choice. In order to make sense of this complex picture, a 10-year housing study has been undertaken in the USC School of Architecture comparing a range of sizes with reference to solar-access policy and design. Data have been systematically collected relating Density (a count of dwelling units per acre) to S/V (surface-to-volume ratio, and energy-related measure of building form). This relationship is taken as grounds for concluding that buildings of 3--7 stories generally represent the best size range for urban dwellings in Los Angeles. These figures can vary among cities; but the underlying suppositions of solar-access policy and design are broadly applicable to places of density everywhere.

  6. Particle Size Analysis.

    Science.gov (United States)

    Barth, Howard G.; Sun, Shao-Tang

    1989-01-01

    Presents a review of research focusing on scattering, elution techniques, electrozone sensing, filtration, centrifugation, comparison of techniques, data analysis, and particle size standards. The review covers the period 1986-1988. (MVL)

  7. Sizing an isolated wind-solar-fuel cell generation system based on the particle swarm optimization method; Dimensionamiento de un sistema de generacion aislado eolico-solar-celda de combustible basado en el metodo de optimizacion de enjambre de particulas

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Huerta, V; Ramirez-Arredondo, Juan M. [Universidad de Quintana Roo, Chetumal, Quintana Roo (Mexico)]. E-mail: vsanchez@gdl.cinvestav.mx; Arriaga-Hurtado, L. G. [CIDETEQ, Queretaro (Mexico)

    2009-09-15

    Sizing an electric energy system requires an analysis of investment, maintenance and operating costs. In the case of a generation system that uses renewable sources, optimal capacity becomes more complex compared to a conventional system, because of the randomness of renewable resources (wind, solar) and the still high costs of wind and photovoltage generator modules. This work presents the optimal sizing of a wind-solar-fuel cell generation system, minimizing the costs of the system while satisfying the energy demands of an isolated charge. The optimization method used is based on an evolutionary programming technique known as particle swarms (PSO-particle swarm optimization). The generation of energy with a hybrid system is discussed, based on the profile of insolation and wind availability at the site, with the objective of satisfying a specific electric demand. [Spanish] El dimensionamiento de un sistema de generacion de energia electrica requiere un analisis de los costos de inversion, mantenimiento y operacion. En el caso de un sistema de generacion que utiliza fuentes renovables la capacidad optima resulta mas compleja con respecto a un sistema convencional, debido a la aleatoriedad de los recursos renovables (eolico, solar), y a los aun altos costos de generadores eolicos y modulos fotovoltaicos. En este trabajo se presenta el dimensionamiento optimo de un sistema de generacion eolico-solar-celda de combustible minimizando los costos del sistema que satisfaga la energia demandada por una carga aislada. El metodo de optimizacion utilizado esta basado en una tecnica de programacion evolutiva conocida como enjambre de particulas (PSO por sus siglas en ingles: particle swarm optimization). Se plantea la generacion de energia del sistema hibrido con base a la insolacion y el perfil del viento disponible en sitio, con objeto de satisfacer una demanda electrica determinada.

  8. Laser-induced transport effect and laser induced-line narrowing mechanism for laser excitation in 87Rb atomic vapors in a finite-size buffer-less cell

    International Nuclear Information System (INIS)

    hyperfine transition weakly depend on the cell size and the type of the coating. When the components of the laser field are comparable the CPT resonance width depends linearly on the laser field intensity. This case was investigated and the formation of CPT resonance on Zeeman sublevels was studied. In contrast for the electromagnetically-induced transparency (EIT) effect (where one laser field is drive and the other - probe) the EIT width increases proportionally to the square root of the drive field intensity. (author)

  9. Spacesuit Soft Upper Torso Sizing Systems

    Science.gov (United States)

    Graziosi, David; Splawn, Keith

    2011-01-01

    The passive sizing system consists of a series of low-profile pulleys attached to the front and back of the shoulder bearings on a spacesuit soft upper torso (SUT), textile cord or stainless steel cable, and a modified commercial ratchet mechanism. The cord/cable is routed through the pulleys and attached to the ratchet mechanism mounted on the front of the spacesuit within reach of the suited subject. Upon actuating the ratchet mechanism, the shoulder bearing breadth is changed, providing variable upper torso sizing. The active system consists of a series of pressurizable nastic cells embedded into the fabric layers of a spacesuit SUT. These cells are integrated to the front and back of the SUT and are connected to an air source with a variable regulator. When inflated, the nastic cells provide a change in the overall shoulder bearing breadth of the spacesuit and thus, torso sizing. The research focused on the development of a high-performance sizing and actuation system. This technology has application as a suit-sizing mechanism to allow easier suit entry and more accurate suit fit with fewer torso sizes than the existing EMU (Extravehicular Mobility Unit) suit system. This advanced SUT will support NASA s Advanced EMU Evolutionary Concept of a two-sizes-fit-all upper torso for replacement of the current EMU hard upper torso (HUT). Both the passive and nastic sizing system approaches provide astronauts with real-time upper torso sizing, which translates into a more comfortable suit, providing enhanced fit resulting in improved crewmember performance during extravehicular activity. These systems will also benefit NASA by reducing flight logistics as well as overall suit system cost. The nastic sizing system approach provides additional structural redundancy over existing SUT designs by embedding additional coated fabric and uncoated fabric layers. Two sizing systems were selected to build into a prototype SUT: one active and one passive. From manned testing, it

  10. Large litter sizes

    DEFF Research Database (Denmark)

    Sandøe, Peter; Rutherford, K.M.D.; Berg, Peer

    2012-01-01

    This paper presents some key results and conclusions from a review (Rutherford et al. 2011) undertaken regarding the ethical and welfare implications of breeding for large litter size in the domestic pig and about different ways of dealing with these implications. Focus is primarily on the direct...... adverse consequences for animal welfare of Danish breeding for large litter sizes due to increased piglet mortality and the subsequent attempts to reverse these consequences by breeding for number of live piglets at day five rather than number of piglets born. By this change of breeding goal it seems...

  11. Size of the Optic Nerve Head and Its Relationship with the Thickness of the Macular Ganglion Cell Complex and Peripapillary Retinal Nerve Fiber Layer in Patients with Primary Open Angle Glaucoma

    Directory of Open Access Journals (Sweden)

    Nobuko Enomoto

    2015-01-01

    Full Text Available Purpose. To evaluate the relationships among the optic nerve head (ONH area, macular ganglion cell complex (mGCC thickness, circumpapillary retinal nerve fiber layer (cpRNFL thickness, and visual field defects in patients with primary open angle glaucoma (POAG. Methods. This retrospective study included 90 eyes of 90 patients with POAG. The ONH area, rim area, mGCC thickness, and cpRNFL thickness were measured using optical coherence tomography. Mean deviation (MD was measured using standard automated perimetry. The relationships among clinical factors including age, refraction, the ONH area, the rim area, the mGCC thickness, the cpRNFL thickness, and MD were evaluated using correlation coefficients and multiple regression analyses. Results. The significant correlation of the ONH area with refraction (r=0.362, P<0.001, the mGCC thickness (r=0.225, P=0.033, and the cpRNFL thickness (r=0.253, P=0.016 was found. Multiple regression analysis showed that the ONH area, rim area, and MD were selected as significant contributing factors to explain the mGCC thickness and cpRNFL thickness. No factor was selected to explain MD. Conclusions. The ONH area, in other words, the disc size itself may affect the mGCC thickness and cpRNFL thickness in POAG patients.

  12. Finite Size Giant Magnon

    CERN Document Server

    Ramadanovic, Bojan

    2008-01-01

    The quantization of the giant magnon away from the infinite size limit is discussed. We argue that this quantization inevitably leads to string theory on a Z_M-orbifold of S^5. This is shown explicitly and examined in detail in the near plane-wave limit.

  13. Size and Reputation

    DEFF Research Database (Denmark)

    Jakobsen, Peter Viggo; Ringsmose, Jens

    2015-01-01

    American public gratitude than the UK. While London has been accused of losing Basra and Musa Qaleh, Copenhagen has been showered with praise and top-posts in NATO. This article explains why demonstrating how the differences in size and reputation gave rise to different expectations of the special...

  14. Sizing Up Visualizations

    DEFF Research Database (Denmark)

    Jakobsen, Mikkel Rønne; Hornbæk, Kasper Anders Søren

    2011-01-01

    Whereas the literature is clear on the benefits of large displays and visualizations, little is known about their combination, that is, how display size affect the usability of visualizations. We describe a controlled experiment where 19 participants used focus+context, overview+detail, and zoomi...

  15. Calculating Optimal Inventory Size

    Directory of Open Access Journals (Sweden)

    Ruby Perez

    2010-01-01

    Full Text Available The purpose of the project is to find the optimal value for the Economic Order Quantity Model and then use a lean manufacturing Kanban equation to find a numeric value that will minimize the total cost and the inventory size.

  16. Cell counting.

    Science.gov (United States)

    Phelan, M C; Lawler, G

    2001-05-01

    This unit presents protocols for counting cells using either a hemacytometer or electronically using a Coulter counter. Cell counting with a hemacytometer permits effective discrimination of live from dead cells using trypan blue exclusion. In addition, the procedure is less subject to errors arising from cell clumping or size heterogeneity. Counting cells is more quickly and easily performed using an electronic counter, but live-dead discrimination is unreliable. Cell populations containing large numbers of dead cells and/or cell clumps are difficult to count accurately. In addition, electronic counting requires resetting of the instrument for cell populations of different sizes; heterogeneous populations can give rise to inaccurate counts, and resting and activated cells may require counting at separate settings. In general, electronic cell counting is best performed on fresh peripheral blood cells. PMID:18770655

  17. Scaling of Foraminifera Parent and Offspring Size through the Phanerozoic

    Science.gov (United States)

    Guo, D.; Holme, F.; Payne, J.; Skotheim, J.

    2011-12-01

    Since before the 1940s, scientists have studied the scaling of body mass with metabolic rate, heart rate, fecundity, cardiac cycling rate, and numerous other traits. Like these traits, offspring mass scales with parent body mass for plants and animals. However, the relationship is not well documented in single-celled organisms. In our study, we examined how adult size scales with embryo size in fusulinid foraminifera. Fusulinids, and most other foraminifera, are an exceptional study group because the proloculus (the initial shell chamber) can be used to measure the size of the daughter cell at the time it became independent of its parent. We find that proloculus size increases with adult test size across fusulinid species. This pattern may result because the genomic sizes and the cellular machinery necessary for a larger adult size place limits on how small the initial daughter cell can be.

  18. Size makes a difference

    DEFF Research Database (Denmark)

    Matthiessen, Jeppe; Fagt, Sisse; Biltoft-Jensen, Anja Pia;

    2003-01-01

    items was obtained from a 4-day weighed food record (Study 1). Trends in portion sizes of commercial foods were examined by gathering information from major food manufacturers and fast food chains (Study 2). Data on intakes and sales of sugar-sweetened soft drinks and confectionery were obtained through...... increased over time, and in particular in the last 10 years. Study 3: The development in portion sizes of commercial foods has been paralleled by a sharp increase of more than 50% in the sales of sugar-sweetened soft drinks and confectionery like sweets, chocolate and ice creams since the 1970s. Conclusions...... nation-wide dietary surveys and official sales statistics (Study 3). Results: Study 1: Subjects ate and drank significantly more when they chose low-fat food and meal items (milk used as a drink, sauce and sliced cold meat), compared with their counterparts who chose food and meal items with a higher fat...

  19. Space power subsystem sizing

    International Nuclear Information System (INIS)

    This paper discusses a Space Power Subsystem Sizing program which has been developed by the Aerospace Power Division of Wright Laboratory, Wright-Patterson Air Force Base, Ohio. The Space Power Subsystem program (SPSS) contains the necessary equations and algorithms to calculate photovoltaic array power performance, including end-of-life (EOL) and beginning-of-life (BOL) specific power (W/kg) and areal power density (W/m2). Additional equations and algorithms are included in the spreadsheet for determining maximum eclipse time as a function of orbital altitude, and inclination. The Space Power Subsystem Sizing program (SPSS) has been used to determine the performance of several candidate power subsystems for both Air Force and SDIO potential applications. Trade-offs have been made between subsystem weight and areal power density (W/m2) as influenced by orbital high energy particle flux and time in orbit

  20. Quenched effective population size

    CERN Document Server

    Sagitov, Serik; Vatutin, Vladimir

    2010-01-01

    We study the genealogy of a geographically - or otherwise - structured version of the Wright-Fisher population model with fast migration. The new feature is that migration probabilities may change in a random fashion. Applying Takahashi's results on Markov chains with random transition matrices, we establish convergence to the Kingman coalescent, as the population size goes to infinity. This brings a novel formula for the coalescent effective population size (EPS). We call it a quenched EPS to emphasize the key feature of our model - random environment. The quenched EPS is compared with an annealed (mean-field) EPS which describes the case of constant migration probabilities obtained by averaging the random migration probabilities over possible environments.

  1. Fire Size in Tunnels

    OpenAIRE

    Carvel, Ricky O

    2004-01-01

    In recent years, a number of high profile accidental fires have occurred in several road and rail tunnels throughout the world. Many of these fires grew rapidly to catastrophic size and claimed many lives. The processes involved in the rapid growth and extremely severe of these fires are not adequately understood as yet. The introduction to this thesis reviews a number of these accidental fires and describes much of the previous experimental research which has brought about the...

  2. Nuclear size isomers

    OpenAIRE

    Ogloblin Alexey; Danilov Andrey; Demyanova Alla; Goncharov Sergey; Belyaeva Tatiana; Trzaska Wladislaw

    2016-01-01

    Developing of methods of measuring the radii of nuclei in their highly excited states led to observation of those with dimensions enhanced and, probably, diminished in comparison with the corresponding ground states. Experimental data including very recent ones demonstrating that such “size isomers” belong to two groups: excited states having neutron halos (in 13C, 11Be and 9 Be) and some specific cluster states (in 12C, 13C and 11B), are discussed.

  3. Aerosol mobility size spectrometer

    Science.gov (United States)

    Wang, Jian; Kulkarni, Pramod

    2007-11-20

    A device for measuring aerosol size distribution within a sample containing aerosol particles. The device generally includes a spectrometer housing defining an interior chamber and a camera for recording aerosol size streams exiting the chamber. The housing includes an inlet for introducing a flow medium into the chamber in a flow direction, an aerosol injection port adjacent the inlet for introducing a charged aerosol sample into the chamber, a separation section for applying an electric field to the aerosol sample across the flow direction and an outlet opposite the inlet. In the separation section, the aerosol sample becomes entrained in the flow medium and the aerosol particles within the aerosol sample are separated by size into a plurality of aerosol flow streams under the influence of the electric field. The camera is disposed adjacent the housing outlet for optically detecting a relative position of at least one aerosol flow stream exiting the outlet and for optically detecting the number of aerosol particles within the at least one aerosol flow stream.

  4. Calculating body frame size (image)

    Science.gov (United States)

    Body frame size is determined by a person's wrist circumference in relation to his height. For example, a man ... would fall into the small-boned category. Determining frame size: To determine the body frame size, measure ...

  5. Sauropod dinosaurs evolved moderately sized genomes unrelated to body size

    OpenAIRE

    Organ, Chris L.; Brusatte, Stephen L.; Stein, Koen

    2013-01-01

    Sauropodomorph dinosaurs include the largest land animals to have ever lived, some reaching up to 10 times the mass of an African elephant. Despite their status defining the upper range for body size in land animals, it remains unknown whether sauropodomorphs evolved larger-sized genomes than non-avian theropods, their sister taxon, or whether a relationship exists between genome size and body size in dinosaurs, two questions critical for understanding broad patterns of genome evolution in di...

  6. Size reduction machine

    Energy Technology Data Exchange (ETDEWEB)

    Fricke, V.

    1999-12-15

    The Size Reduction Machine (SRM) is a mobile platform capable of shearing various shapes and types of metal components at a variety of elevations. This shearing activity can be performed without direct physical movement and placement of the shear head by the operator. The base unit is manually moved and roughly aligned to each cut location. The base contains the electronics: hydraulic pumps, servos, and actuators needed to move the shear-positioning arm. The movable arm allows the shear head to have six axes of movement and to cut to within 4 inches of a wall surface. The unit has a slick electrostatic capture coating to assist in external decontamination. Internal contamination of the unit is controlled by a high-efficiency particulate air (HEPA) filter on the cooling inlet fan. The unit is compact enough to access areas through a 36-inch standard door opening. This paper is an Innovative Technology Summary Report designed to provide potential users with the information they need to quickly determine if a technology would apply to a particular environmental management problem. They also are designed for readers who may recommend that a technology be considered by prospective users.

  7. Size reduction machine

    International Nuclear Information System (INIS)

    The Size Reduction Machine (SRM) is a mobile platform capable of shearing various shapes and types of metal components at a variety of elevations. This shearing activity can be performed without direct physical movement and placement of the shear head by the operator. The base unit is manually moved and roughly aligned to each cut location. The base contains the electronics: hydraulic pumps, servos, and actuators needed to move the shear-positioning arm. The movable arm allows the shear head to have six axes of movement and to cut to within 4 inches of a wall surface. The unit has a slick electrostatic capture coating to assist in external decontamination. Internal contamination of the unit is controlled by a high-efficiency particulate air (HEPA) filter on the cooling inlet fan. The unit is compact enough to access areas through a 36-inch standard door opening. This paper is an Innovative Technology Summary Report designed to provide potential users with the information they need to quickly determine if a technology would apply to a particular environmental management problem. They also are designed for readers who may recommend that a technology be considered by prospective users

  8. Asymptotic size determines species abundance in the marine size spectrum

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Beyer, Jan

    2006-01-01

    The majority of higher organisms in the marine environment display indeterminate growth; that is, they continue to grow throughout their life, limited by an asymptotic size. We derive the abundance of species as a function of their asymptotic size. The derivation is based on size-spectrum theory...

  9. Particle sizes from sectional data

    DEFF Research Database (Denmark)

    Pawlas, Zbynek; Nyengaard, Jens Randel; Jensen, Eva Bjørn Vedel

    2009-01-01

    We propose a new statistical method for obtaining information about particle size distributions from sectional data without specific assumptions about particle shape. The method utilizes recent advances in local stereology. We show how to estimate separately from sectional data the variance due to...... the local stereological estimation procedure and the variance due to the variability of particle sizes in the population. Methods for judging the difference between the distribution of estimated particle sizes and the distribution of true particle sizes are also provided....

  10. Effects of Titanium Dioxide Nanoparticle Aggregate Size on Gene Expression

    OpenAIRE

    Junko Okuda-Shimazaki; Saiko Takaku; Koki Kanehira; Shuji Sonezaki; Akiyohshi Taniguchi

    2010-01-01

    Titanium dioxide (titania) nanoparticle aggregation is an important factor in understanding cytotoxicity. However, the effect of the aggregate size of nanoparticles on cells is unclear. We prepared two sizes of titania aggregate particles and investigated their biological activity by analyzing biomarker expression based on mRNA expression analysis. The aggregate particle sizes of small and large aggregated titania were 166 nm (PDI = 0.291) and 596 nm (PDI = 0.417), respectively. These two siz...

  11. T-lymphocyte subsets, thymic size and breastfeeding in infancy

    DEFF Research Database (Denmark)

    Jeppesen, Dorthe Lisbeth; Hasselbalch, Helle; Lisse, Ida M;

    2004-01-01

    We followed the changes in concentration of T-lymphocyte subsets (CD4+ and CD8+ cells) in peripheral blood and thymus size during infancy. Previous studies have found increased thymus size in breastfed infants. The present study analyzed the association between breastfeeding and the number of CD4...

  12. Coagulation algorithms with size binning

    Science.gov (United States)

    Statton, David M.; Gans, Jason; Williams, Eric

    1994-01-01

    The Smoluchowski equation describes the time evolution of an aerosol particle size distribution due to aggregation or coagulation. Any algorithm for computerized solution of this equation requires a scheme for describing the continuum of aerosol particle sizes as a discrete set. One standard form of the Smoluchowski equation accomplishes this by restricting the particle sizes to integer multiples of a basic unit particle size (the monomer size). This can be inefficient when particle concentrations over a large range of particle sizes must be calculated. Two algorithms employing a geometric size binning convention are examined: the first assumes that the aerosol particle concentration as a function of size can be considered constant within each size bin; the second approximates the concentration as a linear function of particle size within each size bin. The output of each algorithm is compared to an analytical solution in a special case of the Smoluchowski equation for which an exact solution is known . The range of parameters more appropriate for each algorithm is examined.

  13. Finite size effects in neutron star and nuclear matter simulations

    Energy Technology Data Exchange (ETDEWEB)

    Giménez Molinelli, P.A., E-mail: pagm@df.uba.ar; Dorso, C.O.

    2015-01-15

    In this work we study molecular dynamics simulations of symmetric nuclear and neutron star matter using a semi-classical nucleon interaction model. Our aim is to gain insight on the nature of the so-called “finite size effects”, unavoidable in this kind of simulations, and to understand what they actually affect. To do so, we explore different geometries for the periodic boundary conditions imposed on the simulation cell: cube, hexagonal prism and truncated octahedron. For nuclear matter simulations we show that, at sub-saturation densities and low temperatures, the solutions are non-homogeneous structures reminiscent of the “nuclear pasta” phases expected in neutron star matter simulations, but only one structure per cell and shaped by specific artificial aspects of the simulations—for the same physical conditions (i.e. number density and temperature) different cells yield different solutions. The particular shape of the solution at low enough temperature and a given density can be predicted analytically by surface minimization. We also show that even if this behavior is due to the imposition of periodic boundary conditions on finite systems, this does not mean that it vanishes for very large systems, and it is actually independent of the system size. We conclude that, for nuclear matter simulations, the cells' size sets the only characteristic length scale for the inhomogeneities, and the geometry of the periodic cell determines the shape of those inhomogeneities. To model neutron star matter we add a screened Coulomb interaction between protons, and perform simulations in the three cell geometries. Our simulations indeed produce the well known nuclear pasta, with (in most cases) several structures per cell. However, we find that for systems not too large results are affected by finite size in different ways depending on the geometry of the cell. In particular, at the same certain physical conditions and system size, the hexagonal prism yields a

  14. T-lymphocyte subsets, thymic size and breastfeeding in infancy

    DEFF Research Database (Denmark)

    Jeppesen, Dorthe Lisbeth; Hasselbalch, Helle; Lisse, Ida M;

    2004-01-01

    We followed the changes in concentration of T-lymphocyte subsets (CD4+ and CD8+ cells) in peripheral blood and thymus size during infancy. Previous studies have found increased thymus size in breastfed infants. The present study analyzed the association between breastfeeding and the number of CD4......+ and CD8+ cells. Two different populations of infants between birth and 1 year of age were examined. Study Group I: infants with a variable duration of breastfeeding. Study Group II: long-term breastfed infants. In both groups a correlation was found between CD8+ cells and the thymic index at 10 months...... from 8 to 10 months of age; and a positive correlation between the number of breastfeedings per day at 8 months of age, and an increase in CD4+ cells from 8 to 10 months of age (p <0.01). In conclusion, a correlation was found between thymus size and CD8+ cells. Breastfeeding might have both a current...

  15. Sickle Cell Crisis (Pain Crisis)

    Science.gov (United States)

    ... How Can I Help a Friend Who Cuts? Sickle Cell Crisis (Pain Crisis) KidsHealth > For Teens > Sickle Cell ... A A A Text Size What Is a Sickle Cell Crisis? Sickle cell disease changes the shape of ...

  16. Ostracod Body Size Change Across Space and Time

    Science.gov (United States)

    Nolen, L.; Llarena, L. A.; Saux, J.; Heim, N. A.; Payne, J.

    2014-12-01

    Many factors drive evolution, although it is not always clear which factors are more influential. Miller et al. (2009) found that there is a change in geographic disparity in diversity in marine biotas over time. We tested if there was also geographic disparity in body size during different epochs. We used marine ostracods, which are tiny crustaceans, as a study group for this analysis. We also studied which factor is more influential in body size change: distance or time. We compared the mean body size from different geologic time intervals as well as the mean body size from different locations for each epoch. We grouped ostracod occurrences from the Paleobiology Database into 10º x 10º grid cells on a paleogeographic map. Then we calculated the difference in mean size and the distance between the grid cells containing specimens. Our size data came from the Ellis & Messina"Catalogue of Ostracod" as well as the"Treatise on Invertebrate Paleontology". Sizes were calculated by applying the formula for the volume of an ellipsoid to three linear dimensions of the ostracod carapace (anteroposterior, dorsoventral, and right-left lengths). Throughout this analysis we have come to the realization that there is a trend in ostracods towards smaller size over time. Therefore there is also a trend through time of decreasing difference in size between occurrences in different grid cells. However, if time is not taken into account, there is no correlation between size and geographic distance. This may be attributed to the fact that one might not expect a big size difference between locations that are far apart but still at a similar latitude (for example, at the equator). This analysis suggests that distance alone is not the main factor in driving changes in ostracod size over time.

  17. Tumor heterogeneity, tumor size, and radioresistance

    International Nuclear Information System (INIS)

    Mutant clonogenic cells, resistant to individual chemotherapeutic agents, are known to play a central role in clinical chemotherapy failure. The possibility that mutant cells, resistant to conventionally fractionated megavoltage photon radiotherapy, exist in human tumors is considered. Applying the mutation theory of Luria and Delbruck to describe the appearance of resistant cells, several conclusions follow: (a) the mean number of resistant cells in a tumor will be determined by the tumor size and the mutation rate; (b) a wide variation in radiosensitivity in tumors of the same histology is expected, because of a large variation in the number of resistant cells that they contain; (c) the presence of a resistant clone will not reduce the tumor-control probability until the tumor becomes sufficiently large; (d) initial response will not be a reliable predictor of long-term control; (e) clonogenic assays may not accurately predict treatment outcomes; (f) the mutation rate may be the most accurate predictor of tumor aggressiveness and resistance to various treatment modalities; (g) tumors with a low mutation rate, which may include seminoma, Hodgkin's disease and many pediatric tumors would be curable by either chemotherapy or radiation; (h) pleomorphic tumors with a high mutation rate, which may include glioblastoma multiforme, would be difficult to cure by any means. Clinical and experimental evidence is reviewed for the existence of radioresistant cell lines in human and animal tumors, and further experiments are proposed to test this hypothesis. Treatment strategies for targeting radioresistant clones are discussed

  18. Effective sizes for subdivided populations.

    Science.gov (United States)

    Chesser, R K; Rhodes, O E; Sugg, D W; Schnabel, A

    1993-12-01

    Many derivations of effective population sizes have been suggested in the literature; however, few account for the breeding structure and none can readily be expanded to subdivided populations. Breeding structures influence gene correlations through their effects on the number of breeding individuals of each sex, the mean number of progeny per female, and the variance in the number of progeny produced by males and females. Additionally, hierarchical structuring in a population is determined by the number of breeding groups and the migration rates of males and females among such groups. This study derives analytical solutions for effective sizes that can be applied to subdivided populations. Parameters that encapsulate breeding structure and subdivision are utilized to derive the traditional inbreeding and variance effective sizes. Also, it is shown that effective sizes can be determined for any hierarchical level of population structure for which gene correlations can accrue. Derivations of effective sizes for the accumulation of gene correlations within breeding groups (coancestral effective size) and among breeding groups (intergroup effective size) are given. The results converge to traditional, single population measures when similar assumptions are applied. In particular, inbreeding and intergroup effective sizes are shown to be special cases of the coancestral effective size, and intergroup and variance effective sizes will be equal if the population census remains constant. Instantaneous solutions for effective sizes, at any time after gene correlation begins to accrue, are given in terms of traditional F statistics or transition equations. All effective sizes are shown to converge upon a common asymptotic value when breeding tactics and migration rates are constant. The asymptotic effective size can be expressed in terms of the fixation indices and the number of breeding groups; however, the rate of approach to the asymptote is dependent upon dispersal

  19. Materialised Ideals Sizes and Beauty

    OpenAIRE

    Kirsi Laitala; Ingun Grimstad Klepp; Benedicte Hauge

    2011-01-01

    Today’s clothing industry is based on a system where clothes are made in ready-to-wear sizes and meant to fit most people. Studies have pointed out that consumers are discontent with the use of these systems: size designations are not accurate enough to find clothing that fits, and different sizes are poorly available. This article discusses in depth who these consumers are, and which consumer groups are the most dissatisfied with today’s sizing systems. Results are based on a web survey wher...

  20. Pore-size ion-size correlations for carbon supercapacitors

    Science.gov (United States)

    Chmiola, John

    2009-08-01

    Carbon supercapacitors, which are energy storage devices that use ion adsorption on the surface of highly porous materials to store charge, have numerous advantages over other power-source technologies, but could realize further gains if their electrodes were properly optimized. This could lead to fleet-wide improvements in economy, performance, lifetime and environmental impact of Hybrid Electric Vehicles (HEVs), as well as enable or advance many other applications. To determine correlations between ion-size and pore-size in carbon supercapacitors, we generated a well-characterized set of porous carbide-derived carbons (CDC) with average pore sizes from 0.6 to 2.25 nm and used them to probe the limits of understanding. Performing the first systematic study of the effect of pore size on capacitance showed that, in general, decreasing the pore size below the size of the solvated ion, or to precisely the size of the ionic liquid ion, allowed higher accumulation of charge. Using CDC with properly tuned porosity showed excellent performance in H2SO 4, ˜200 F/g, and performance superior to all prior reported results in organic (CH3CH2)4NBF4 (TEABF 4) electrolytes as well as l-ethyl-3-methyl immidazolium bis-(trifluoromethanesulfonyl)imide (EMI-TFSI) ionic liquid, ˜150 F/g. This work conclusively showed that precisely matching the pore size with the ion size is the key factor for maximizing capacitance. Understanding that pores significantly larger than the effective ion size do not have large contributions to energy storage, work on dense porous CDC films on conductive substrates showed ˜100% larger volumetric capacitance than any previously reported. Depositing patterned films of carbide and electrical contacts could lead to microfabricated energy storage devices directly on a chip, or built up in layers for performances yet unrealized.

  1. Use of CMEIAS Image Analysis Software to Accurately Compute Attributes of Cell Size, Morphology, Spatial Aggregation and Color Segmentation that Signify in Situ Ecophysiological Adaptations in Microbial Biofilm Communities

    Directory of Open Access Journals (Sweden)

    Frank B. Dazzo

    2015-03-01

    Full Text Available In this review, we describe computational features of computer-assisted microscopy that are unique to the Center for Microbial Ecology Image Analysis System (CMEIAS software, and examples illustrating how they can be used to gain ecophysiological insights into microbial adaptations occurring at micrometer spatial scales directly relevant to individual cells occupying their ecological niches in situ. These features include algorithms that accurately measure (1 microbial cell length relevant to avoidance of protozoan bacteriovory; (2 microbial biovolume body mass relevant to allometric scaling and local apportionment of growth-supporting nutrient resources; (3 pattern recognition rules for morphotype classification of diverse microbial communities relevant to their enhanced fitness for success in the particular habitat; (4 spatial patterns of coaggregation that reveal the local intensity of cooperative vs. competitive adaptations in colonization behavior relevant to microbial biofilm ecology; and (5 object segmentation of complex color images to differentiate target microbes reporting successful cell-cell communication. These unique computational features contribute to the CMEIAS mission of developing accurate and freely accessible tools of image bioinformatics that strengthen microscopy-based approaches for understanding microbial ecology at single-cell resolution.

  2. Finite data-size scaling of clustering in earthquake networks

    CERN Document Server

    Abe, Sumiyoshi; Suzuki, Norikazu

    2010-01-01

    Earthquake network introduced in the work [S. Abe and N. Suzuki, Europhys.Lett. 65, 581 (2004)] is known to be of the small-world type. The values of the network characteristics, however, depend not only on the cell size (i.e., the scale of coarse graining needed for constructing the network) but also on the size of a seismic data set. Here, discovery of a scaling law for the clustering coefficient in terms of the data size, which is refereed to here as finite data-size scaling, is reported. Its universality is shown to be supported by the detailed analysis of the data taken from California, Japan, and Iran.

  3. Cellular Manufacturing System with Dynamic Lot Size Material Handling

    Science.gov (United States)

    Khannan, M. S. A.; Maruf, A.; Wangsaputra, R.; Sutrisno, S.; Wibawa, T.

    2016-02-01

    Material Handling take as important role in Cellular Manufacturing System (CMS) design. In several study at CMS design material handling was assumed per pieces or with constant lot size. In real industrial practice, lot size may change during rolling period to cope with demand changes. This study develops CMS Model with Dynamic Lot Size Material Handling. Integer Linear Programming is used to solve the problem. Objective function of this model is minimizing total expected cost consisting machinery depreciation cost, operating costs, inter-cell material handling cost, intra-cell material handling cost, machine relocation costs, setup costs, and production planning cost. This model determines optimum cell formation and optimum lot size. Numerical examples are elaborated in the paper to ilustrate the characterictic of the model.

  4. Adipocyte size fluctuation, mechano-active lipid droplets and caveolae

    OpenAIRE

    Le Lay, Soazig; Briand, Nolwenn; Dugail, Isabelle

    2014-01-01

    Recent data indicate that cell size fluctuation, a key property in adipocyte pathophysiology primarily dependent on lipid storage, is linked to a novel function of lipid droplet organelles acting as mechano-active organelles to regulate cell membrane remodeling and caveolae dynamics.

  5. Bioimpacts of nanoparticle size: why it matters?

    Directory of Open Access Journals (Sweden)

    Jaleh Barar

    2015-08-01

    Full Text Available During the last two decades, applications of nanotechnology are delivered to benefit the human society. The fact is that various nanomaterials are able to be tailor made to achieve desired properties. In biomedical field, nanotechnology has created great excitements to advance both diagnosis and therapy areas – the field so-called nanomedicines in different forms of nanoparticles (NPs and nanosystems (NSs. It is noteworthy to mention NPs/NSs do not act similarly in the biological milieu, in which their biological behaviors/impacts varies with size, morphology, and physicochemical characteristics. On the other hand, nanomedicines impacts on biological systems seem to be influenced by its possible interaction(s with different bioelements of cell membrane, in particular the endocytic pathway(s by which NPs/NSs can be internalized and localized. This latter phenomenon is influenced by membrane viscoelastic property, polymerization/depolymerization of cytoskeletal system, and the particle specification itself. Among all other properties of NPs/NSs, as shown by various researchers, the size is an important parameter in the fate of the particle. Accordingly, in-depth efforts to unravel the size dependent effects of nanomedicins can provide insights to design and develop more efficacious NSs with greater benefits and lower side effects. This editorial aims to highlight some important aspects of size dependent impacts NPs/NSs.

  6. Origin of size effect on efficiency of organic photovoltaics

    DEFF Research Database (Denmark)

    Manor, Assaf; Katz, Eugene A.; Tromholt, Thomas;

    2011-01-01

    It is widely accepted that efficiency of organic solar cells could be limited by their size. However, the published data on this effect are very limited and none of them includes analysis of light intensity dependence of the key cell parameters. We report such analysis for bulk heterojunction solar...... voltage dependence of photocurrent and dark current is the key to understanding size limitation of the organic photovoltaics (OPV) efficiency. Practical methods to overcome this limitation as well as the possibility of producing concentrator OPV cells operating under sunlight concentrations higher than 10...

  7. Food aroma affects bite size

    Directory of Open Access Journals (Sweden)

    de Wijk René A

    2012-03-01

    Full Text Available Abstract Background To evaluate the effect of food aroma on bite size, a semisolid vanilla custard dessert was delivered repeatedly into the mouth of test subjects using a pump while various concentrations of cream aroma were presented retronasally to the nose. Termination of the pump, which determined bite size, was controlled by the subject via a push button. Over 30 trials with 10 subjects, the custard was presented randomly either without an aroma, or with aromas presented below or near the detection threshold. Results Results for ten subjects (four females and six males, aged between 26 and 50 years, indicated that aroma intensity affected the size of the corresponding bite as well as that of subsequent bites. Higher aroma intensities resulted in significantly smaller sizes. Conclusions These results suggest that bite size control during eating is a highly dynamic process affected by the sensations experienced during the current and previous bites.

  8. Direct and Indirect Evidence of Size-Selective Grazing on Pelagic Bacteria by Freshwater Nanoflagellates

    OpenAIRE

    Šimek, Karel; Chrzanowski, Thomas H.

    1992-01-01

    Size-selective grazing of three heterotrophic nanoflagellates (with cell sizes of 21, 44, and 66 μm3) isolated from Lake Arlington, Texas was examined by using a natural mixture of fluorescence labelled lake bacteria. Sizes of ingested bacteria in food vacuoles were directly measured. Larger bacterial cells were ingested at a frequency much higher than that at which they occurred in the assemblage, indicating preferential flagellate grazing on the larger size classes within the lake bacteriop...

  9. Brassinosteroid perception in the epidermis controls root meristem size

    OpenAIRE

    Hacham, Yael; Holland, Neta; Butterfield, Cristina; Ubeda-Tomas, Susana; Bennett, Malcolm J.; Chory, Joanne; Savaldi-Goldstein, Sigal

    2011-01-01

    Multiple small molecule hormones contribute to growth promotion or restriction in plants. Brassinosteroids (BRs), acting specifically in the epidermis, can both drive and restrict shoot growth. However, our knowledge of how BRs affect meristem size is scant. Here, we study the root meristem and show that BRs are required to maintain normal cell cycle activity and cell expansion. These two processes ensure the coherent gradient of cell progression, from the apical to the basal meristem. In add...

  10. Materialised Ideals Sizes and Beauty

    Directory of Open Access Journals (Sweden)

    Kirsi Laitala

    2011-04-01

    Full Text Available Today’s clothing industry is based on a system where clothes are made in ready-to-wear sizes and meant to fit most people. Studies have pointed out that consumers are discontent with the use of these systems: size designations are not accurate enough to find clothing that fits, and different sizes are poorly available. This article discusses in depth who these consumers are, and which consumer groups are the most dissatisfied with today’s sizing systems. Results are based on a web survey where 2834 Nordic consumers responded, complemented with eight in-depth interviews, market analysis on clothing sizes and in-store trouser size measurements. Results indicate that higher shares of the consumers who have a body out of touch with the existing beauty ideals express discontentment with the sizing systems and the poor selection available. In particular, large women, very large men, and thin, short men are those who experience less priority in clothing stores and have more difficulties in finding clothes that fit. Consumers tend to blame themselves when the clothes do not fit their bodies, while our study points out that the industry is to blame as they do not produce clothing for all customers.

  11. Relative eye size in elasmobranchs.

    Science.gov (United States)

    Lisney, Thomas J; Collin, Shaun P

    2007-01-01

    Variation in relative eye size was investigated in a sample of 46 species of elasmobranch, 32 species of sharks and 14 species of batoids (skates and rays). To get a measure of eye size relative to body size, eye axial diameter was scaled with body mass using least-squares linear regression, using both raw species data, where species are treated as independent data points, and phylogenetically independent contrasts. Residual values calculated for each species, using the regression equations describing these scaling relationships, were then used as a measure of relative eye size. Relative and absolute eye size varies considerably in elasmobranchs, although sharks have significantly relatively larger eyes than batoids. The sharks with the relatively largest eyes are oceanic species; either pelagic sharks that move between the epipelagic (0-200 m) and 'upper' mesopelagic (200-600 m) zones, or benthic and benthopelagic species that live in the mesopelagic (200-1,000 m) and, to a lesser extent, bathypelagic (1,000-4,000 m) zones. The elasmobranchs with the relatively smallest eyes tend to be coastal, often benthic, batoids and sharks. Active benthopelagic and pelagic species, which prey on active, mobile prey also have relatively larger eyes than more sluggish, benthic elasmobranchs that feed on more sedentary prey such as benthic invertebrates. A significant positive correlation was found between absolute eye size and relative eye size, but some very large sharks, such as Carcharodon carcharias have absolutely large eyes, but have relatively small eyes in relation to body mass. PMID:17314474

  12. Nanofluidic Size-Exclusion Chromatograph

    Science.gov (United States)

    Feldman, Sabrina; Svehla, Danielle; Grunthaner, Frank; Feldman, Jason; Shakkottai, P.

    2004-01-01

    Efforts are under way to develop a nanofluidic size-exclusion chromatograph (SEC), which would be a compact, robust, lightweight instrument for separating molecules of interest according to their sizes and measuring their relative abundances in small samples. About as large as a deck of playing cards, the nanofluidic SEC would serve, in effect, as a laboratory on a chip that would perform the functions of a much larger, conventional, bench-top SEC and ancillary equipment, while consuming much less power and much smaller quantities of reagent and sample materials. Its compactness and low power demand would render it attractive for field applications in which, typically, it would be used to identify and quantitate a broad range of polar and nonpolar organic compounds in soil, ice, and water samples. Size-exclusion chromatography is a special case of high-performance liquid chromatography. In a conventional SEC, a sample plug is driven by pressure along a column packed with silica or polymer beads that contain uniform nanopores. The interstices between, and the pores in, the beads collectively constitute a size-exclusion network. Molecules follow different paths through the size-exclusion network, such that characteristic elution times can be related to sizes of molecules: basically, smaller molecules reach the downstream end of the column after the larger ones do because the smaller ones enter minor pores and stay there for a while, whereas the larger ones do not enter the pores. The volume accessible to molecules gradually diminishes as their size increases. All molecules bigger than a pore size elute together. For most substances, the elution times and sizes of molecules can be correlated directly with molecular weights. Hence, by measuring the flux of molecules arriving at the downstream end as a function of time, one can obtain a liquid mass spectrum for the molecules present in a sample over a broad range of molecular weights.

  13. Analysis of glass fibre sizing

    DEFF Research Database (Denmark)

    Petersen, Helga Nørgaard; Kusano, Yukihiro; Brøndsted, Povl;

    2014-01-01

    Glass fibre reinforced polymer composites are widely used for industrial and engineering applications which include construction, aerospace, automotive and wind energy industry. During the manufacturing glass fibres, they are surface-treated with an aqueous solution. This process and the treated...... surfaces are called sizing. The sizing influences the properties of the interface between fibres and a matrix, and subsequently affects mechanical properties of composites. In this work the sizing of commercially available glass fibres was analysed so as to study the composition and chemical structures...

  14. Aerosol Size Distributions In Auckland.

    Czech Academy of Sciences Publication Activity Database

    Coulson, G.; Olivares, G.; Talbot, Nicholas

    2016-01-01

    Roč. 50, č. 1 (2016), s. 23-28. E-ISSN 1836-5876 Institutional support: RVO:67985858 Keywords : aerosol size distribution * particle number concentration * roadside Subject RIV: CF - Physical ; Theoretical Chemistry

  15. Sibship Size and Educational Attainment

    DEFF Research Database (Denmark)

    Jæger, Mads Meier

    2009-01-01

    Studies on family background often explain the negative effect of sibship size on educational attainment by one of two theories: the Confluence Model (CM) or the Resource Dilution Hypothesis (RDH). However, as both theories - for substantively different reasons - predict that sibship size should...... distinguish the two theories and to identify a unique RDH effect on educational attainment. Using sibling data from the Wisconsin Longitudinal Study (WLS) and a random effect Instrumental Variable model I find that, in addition to a negative effect on cognitive ability, sibship size also has a strong negative...... have a negative effect on educational attainment most studies cannot distinguish empirically between the CM and the RDH. In this paper I use the different theoretical predictions in the CM and RDH on the role of cognitive ability as a partial or complete mediator of the effect of sibship size to...

  16. Variable Size Genetic Network Programming

    Science.gov (United States)

    Katagiri, Hironobu; Hirasawa, Kotaro; Hu, Jinglu; Murata, Junichi

    Genetic Network Programming (GNP) is a kind of volutionary methods, which evolves arbitrary directed graph programs. Previously, the program size of GNP was fixed. In the paper, a new method is proposed, where the program size is adaptively changed depending on the frequency of the use of nodes. To control and to decide a program size are important and difficult problems in Evolutionary Computation, especially, a well-known crossover operator tends to cause bloat. We introduce two additional operators, add operator and delete operator, that can change the number of each kind of nodes based on whether a node function is important in the environment or not. Simulation results shows that the proposed method brings about extremely better results compared with ordinary fixed size GNP.

  17. Size scaling of static friction

    OpenAIRE

    Braun, O. M.; Manini, Nicola; Tosatti, Erio

    2013-01-01

    Sliding friction across a thin soft lubricant film typically occurs by stick-slip, the lubricant fully solidifying at stick, yielding and flowing at slip. The static friction force per unit area preceding slip is known from molecular dynamics (MD) simulations to decrease with increasing contact area. That makes the large-size fate of stick-slip unclear and unknown; its possible vanishing is important as it would herald smooth sliding with a dramatic drop of kinetic friction at large size. Her...

  18. Experimental determination of size distributions: analyzing proper sample sizes

    Science.gov (United States)

    Buffo, A.; Alopaeus, V.