Science.gov

Sample records for fiber cells

  1. Stretchable polymer solar cell fibers.

    PubMed

    Zhang, Zhitao; Yang, Zhibin; Deng, Jue; Zhang, Ye; Guan, Guozhen; Peng, Huisheng

    2015-02-11

    Power yourself up: a sweater made from solar cells! Stretchable and wearable fibers are shown to be highly efficient polymer solar cells. Their stable energy conversion efficiency variation is below 10% even after 1000 bending cycles or stretching under a strain of 30%. These fibers can easily be woven into fabric from which any type of clothing can be made.

  2. Self Regulating Fiber Fuel Cell

    DTIC Science & Technology

    2010-08-16

    energy numbers are 2.3X and 5.7X the theoretical values for lithium thionyl chloride respectively (1100 Whr/liter and 590 Whr/kg), which has the...REPORT Self Regulating Fiber Fuel Cell 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Advances in lithium primary battery technology, which serves as the...Prescribed by ANSI Std. Z39.18 - 16-Aug-2010 Self Regulating Fiber Fuel Cell Report Title ABSTRACT Advances in lithium primary battery technology

  3. Cells on foam and fiber

    SciTech Connect

    Clyde, R.

    1995-11-01

    Cells growing on high area foam and when a screen is put around the foam, it is made heavier so it can be fluidized. When foam is rotated in a half full RBC, drops are formed and mass transfer of oxygen to drops in much faster. Most fungi and some mammalian cells need oxygen. Corrugated fibers with holes in the valleys also produce drops. White rot fungus needs oxygen and it degrades many chlorine compounds, azo dyes, and TNT. Old cardboard boxes are readily available and when buried in soil, oxygen is entrapped. In a lake, the boxes expose high area. Fibers have high surface area for immobilizing cells and when the fibers are rotated, fast reactions occur, converting one chemical to another. Sugar has been fermented to alcohol in 10-15 minutes. Ethanol has high octane and does not need lead. Old cars and trucks still use lead and high levels have been found in the drinking water of several large cities. Bacteria on fibers can remove lead in a few seconds. When an RBC of plain fiber discs is rotated and a light shone in the top the light hits a thin moving film to degrade chlorine compounds. Microbes and light remove sulfur from oil. Calcium magnesium acetate is a non corrosive road deicer. Salt on roads causes millions of dollars damage to bridges and cars. An inexpensive reactor has been made for organization studies of mammalian and plant cells. A magnet is near the bottom but not touching and oxygen is put on the top where there is no seal that can leak.

  4. Glycoproteome of Elongating Cotton Fiber Cells*

    PubMed Central

    Kumar, Saravanan; Kumar, Krishan; Pandey, Pankaj; Rajamani, Vijayalakshmi; Padmalatha, Kethireddy Venkata; Dhandapani, Gurusamy; Kanakachari, Mogilicherla; Leelavathi, Sadhu; Kumar, Polumetla Ananda; Reddy, Vanga Siva

    2013-01-01

    Cotton ovule epidermal cell differentiation into long fibers primarily depends on wall-oriented processes such as loosening, elongation, remodeling, and maturation. Such processes are governed by cell wall bound structural proteins and interacting carbohydrate active enzymes. Glycosylation plays a major role in the structural, functional, and localization aspects of the cell wall and extracellular destined proteins. Elucidating the glycoproteome of fiber cells would reflect its wall composition as well as compartmental requirement, which must be system specific. Following complementary proteomic approaches, we have identified 334 unique proteins comprising structural and regulatory families. Glycopeptide-based enrichment followed by deglycosylation with PNGase F and A revealed 92 unique peptides containing 106 formerly N-linked glycosylated sites from 67 unique proteins. Our results showed that structural proteins like arabinogalactans and carbohydrate active enzymes were relatively more abundant and showed stage- and isoform-specific expression patterns in the differentiating fiber cell. Furthermore, our data also revealed the presence of heterogeneous and novel forms of structural and regulatory glycoproteins. Comparative analysis with other plant glycoproteomes highlighted the unique composition of the fiber glycoproteome. The present study provides the first insight into the identity, abundance, diversity, and composition of the glycoproteome within single celled cotton fibers. The elucidated composition also indirectly provides clues about unicellular compartmental requirements underlying single cell differentiation. PMID:24019148

  5. Hybrid solar cell on a carbon fiber

    NASA Astrophysics Data System (ADS)

    Grynko, Dmytro A.; Fedoryak, Alexander N.; Smertenko, Petro S.; Dimitriev, Oleg P.; Ogurtsov, Nikolay A.; Pud, Alexander A.

    2016-05-01

    In this work, a method to assemble nanoscale hybrid solar cells in the form of a brush of radially oriented CdS nanowire crystals around a single carbon fiber is demonstrated for the first time. A solar cell was assembled on a carbon fiber with a diameter of ~5-10 μm which served as a core electrode; inorganic CdS nanowire crystals and organic dye or polymer layers were successively deposited on the carbon fiber as active components resulting in a core-shell photovoltaic structure. Polymer, dye-sensitized, and inverted solar cells have been prepared and compared with their analogues made on the flat indium-tin oxide electrode.

  6. Cells on foam and fiber

    SciTech Connect

    Clyde, R.

    1996-12-31

    Some bacteria secrete an insoluble organic polymer in which colonies of bacteria become embedded and adhere to surfaces. Some fungi also form colonies. Their metabolic functions and interactions become enhanced, offering opportunities for increased efficiency in many biological waste remediation and bioreaction processes if a large surface area is available. Plastic foam and sponge encased in wire mesh, perforated cardboard, fibers, fiber discs, and titanium dioxide on fiberglass are a few examples of large surface areas, which, if oxygen is required, can be rotated in a rotating biological contactor (RBC) to increases oxygen contact and provide greatly increased bacterial activity. Ethanol fermentation is accomplished quickly. Lead and other toxic metals are quickly immobilized in bacteria. If light is required the thin liquid film enhances reactivity to quickly degrade chlorine compounds or remove sulfur from oil. Production of calcium magnesium acetate, a non-corrosive road deicer, can also be efficiently produced in this manner. Some primitive fungi also form colonies, notably the slime molds and filament-forming fungi, that enhance their biological effects. White rot fungus readily degrades chlorine compounds, azo dyes, TNT, and polycyclic aromatic hydrocarbons (PHA), for example.

  7. Cell Fractionation and Arrangement on Fibers, Beads, and Surfaces

    PubMed Central

    Edelman, G. M.; Rutishauser, U.; Millette, C. F.

    1971-01-01

    A new method, fiber fractionation, has been used to isolate and separate cells. The cells are adsorbed to fibers covalently coupled to molecules such as antigens, antibodies, and lectins which can bind specifically to cell-surface components. The cells are then removed mechanically by plucking the taut fibers. Alternatively, competitive inhibitors of binding may be used to remove the cells at a lesser rate. Successful fractionations have been achieved by varying the degree of derivatization of the fibers by the lectin concanavalin A. Lymphoid cells have been separated by the use of different antigens coupled to the fibers. The method may also be used for specific fixation and manipulation of viable cell populations in culture. In addition to fibers, beads and surfaces have been specifically derivatized and used to achieve different geometrical arrangements of the cells. Images PMID:5289374

  8. Hollow-fiber H2/O2 fuel cell

    NASA Technical Reports Server (NTRS)

    Ingham, J. D.; Lawson, D. D.

    1977-01-01

    Dual-membrane hollow-fiber electrode increases reliability and lowers costs. Leakage of fuel or oxidizer through fiber does not result in failure; excess product water migrates into electrolyte where it is removed by evaporation or distillation; constant exposure of fiber to electrolyte eliminates problems of drying and consequent failure; reference electrode monitors current collectors and overall cell performance.

  9. Hollow-fiber H2/O2 fuel cell

    NASA Technical Reports Server (NTRS)

    Ingham, J. D.; Lawson, D. D.

    1977-01-01

    Dual-membrane hollow-fiber electrode increases reliability and lowers costs. Leakage of fuel or oxidizer through fiber does not result in failure; excess product water migrates into electrolyte where it is removed by evaporation or distillation; constant exposure of fiber to electrolyte eliminates problems of drying and consequent failure; reference electrode monitors current collectors and overall cell performance.

  10. Self-regulating fiber fuel cell

    NASA Astrophysics Data System (ADS)

    Eickhoff, Steven J.

    2010-04-01

    Advances in lithium primary battery technology, which serves as the gold standard power source for the dismounted soldier, have not kept pace with the ever increasing power and energy requirements of modern military electronic equipment. Fuel cells have long been touted as the solution to the dismounted soldier's power and energy problems, but until recently, have largely failed to live up to that promise. There is still a pressing need for better power sources at the Watt or sub-Watt level, especially in applications requiring nontraditional form factors (thin, prismatic) or those having special requirements like flexibility or conformability, where existing battery technology falls short. To address these needs, Honeywell is developing a Self Regulating Fiber Fuel Cell, which utilizes a novel fuel chemistry and regulation mechanism and micro fabrication techniques to create a flexible, conformal power source with substantially better energy density and specific energy compared to state of the art lithium primary batteries. This paper will cover Honeywell's progress on the Fiber Fuel Cell Project.

  11. Actin Filament Stress Fibers in Vascular Endothelial Cells in vivo

    NASA Astrophysics Data System (ADS)

    Wong, Albert J.; Pollard, Thomas D.; Herman, Ira M.

    1983-02-01

    Fluorescence microscopy with 7-nitrobenz-2-oxa-3-diazole phallacidin was used to survey vertebrate tissues for actin filament bundles comparable to the stress fibers of cultured cells. Such bundles were found only in vascular endothelial cells. Like the stress fibers of cultured cells, these actin filament bundles were stained in a punctate pattern by fluorescent antibodies to both alpha-actinin and myosin. The stress fibers were oriented parallel to the direction of blood flow and were prominent in endothelial cells from regions exposed to high-velocity flow, such as the left ventricle, aortic valve, and aorta. Actin bundles may help the endothelial cell to withstand hemodynamic stress.

  12. Hollow fiber clinostat for simulating microgravity in cell culture

    NASA Technical Reports Server (NTRS)

    Rhodes, Percy H. (Inventor); Miller, Teresa Y. (Inventor); Snyder, Robert S. (Inventor)

    1992-01-01

    A clinostat for simulating microgravity on cell systems carried in a fiber fixedly mounted in a rotatable culture vessel is disclosed. The clinostat is rotated horizontally along its longitudinal axis to simulate microgravity or vertically as a control response. Cells are injected into the fiber and the ends of the fiber are sealed and secured to spaced end pieces of a fiber holder assembly which consists of the end pieces, a hollow fiber, a culture vessel, and a tension spring with three alignment pins. The tension spring is positioned around the culture vessel with its ends abutting the end pieces for alignment of the spring. After the fiber is secured, the spring is decompressed to maintain tension on the fiber while it is being rotated. This assures that the fiber remains aligned along the axis of rotation. The fiber assembly is placed in the culture vessel and culture medium is added. The culture vessel is then inserted into the rotatable portion of the clinostat and subjected to rotate at selected rpms. The internal diameter of the hollow fiber determines the distance the cells are from the axis of rotation.

  13. [The development, differentiation and composition of flax fiber cells].

    PubMed

    Preisner, Marta; Wojtasik, Wioleta; Szopa, Jan; Kulma, Anna

    2015-01-01

    Having vascular origin, flax fiber belongs to the sclerenchyma (steroids) and its structure is limited to the cell wall. What determines fiber properties is its composition, which in practice means the composition of the secondary cell wall. It consists of four main polymers which constitute approximately 90% of the fiber: cellulose, hemicellulose, pectin, lignin, and a variety of secondary metabolites, proteins, waxes and inorganic compounds. The cell wall is a structure with a high complexity of both the composition and interactions of the particular elements between themselves. It is determined by differentiation and cell growth as well as environmental factors, biotic and abiotic stresses. The molecular background of these processes and mechanisms regulating the synthesis and rearrangement of secondary cell walls components are being intensively studied. In this work we described the latest news about the development, composition and metabolism of flax fiber cell wall components together with the molecular explanation of these processes.

  14. Influence of well-defined mineral fibers on proliferating cells.

    PubMed Central

    Tilkes, F; Beck, E G

    1983-01-01

    The effects of well-defined asbestos and man-made mineral fibers, as well as glass and synthetic fluoroamphibole, on phagocytizing permanent rat tumor cells were tested. The following parameters were compared: cell proliferation as determined by cell count and 3H-thymidine incorporation, RNA synthesis by 3H-uridine uptake, protein synthesis by incorporation of 3H-labeled amino acids, protein content and plasma membrane permeability by release of lactic dehydrogenase. The dosage of most of the dusts was estimated gravimetrically, but for some dusts also numerically. Because of the wide range of different fibers lengths, diameters and specific weights, it was sometimes difficult to compare chemically and physically differing fiber fractions with the same fiber counts. In some cases, resulting weights are so different that a direct comparison of the conclusions is impossible. The results with fibers of diverse sources showed the same trends: the toxicity of fibers increases with increasing length and dose. In this test system we found an inhibition of DNA and RNA synthesis. Protein synthesis as measured by amino acid uptake per total cell culture decreased, but the protein content of the single cell increased as determined by the Lowry method. The increase of plasma membrane permeability as determined by lactic dehydrogenase was also dependent on fiber length and concentration. Generally the thinner the fiber, the greater the toxicity when gravimetrical dosage and the same length distributions are employed. Beyond that we can state that the toxicity of fibers from different sources with similar fiber dimensions is similar. One of the glass fiber fractions has a comparable geometry (length, diameter) to the UICC fraction of chrysotile and exhibits the same high toxicity. PMID:6196187

  15. Hollow fiber culture accelerates differentiation of Caco-2 cells.

    PubMed

    Deng, Xudong; Zhang, Guoliang; Shen, Chong; Yin, Jian; Meng, Qin

    2013-08-01

    Caco-2 cells usually require 21 days of culture for developing sufficient differentiation in traditional two-dimensional Transwell culture, deviating far away from the quick differentiation of enterocytes in vivo. The recently proposed three-dimensional cultures of Caco-2 cells, though imitating the villi/crypt-like microstructure of intestinal epithelium, showed no effect on accelerating the differentiation of Caco-2 cells. In this study, a novel culture of Caco-2 cells on hollow fiber bioreactor was applied to morphologically mimic the human small intestine lumen for accelerating the expression of intestine functions. The porous hollow fibers of polyethersulfone (PES), a suitable membrane material for Caco-2 cell culture, successfully promoted cells to form confluent monolayer on the inner surface. The differentiated functions of Caco-2 cells, represented by alkaline phosphatase, γ-glutamyltransferase, and P-glycoprotein activity, were greatly higher in a 10-day hollow fiber culture than in a 21-day Transwell culture. Moreover, the Caco-2 cells on PES hollow fibers expressed higher F-actin and zonula occludens-1 protein than those on Transwell culture, indicative of an increased mechanical stress in Caco-2 cells on PES hollow fibers. The accelerated differentiation of Caco-2 cells on PES hollow fibers was unassociated with membrane chemical composition and surface roughness, but could be stimulated by hollow fiber configuration, since PES flat membranes with either rough or smooth surface failed to enhance the differentiation of Caco-2. Therefore, the accelerated expression of Caco-2 cell function on hollow fiber culture might show great values in simulation of the tissue microenvironment in vivo and guide the construction of intestinal tissue engineering apparatus.

  16. Hollow fiber: a biophotonic implant for live cells

    NASA Astrophysics Data System (ADS)

    Silvestre, Oscar F.; Holton, Mark D.; Summers, Huw D.; Smith, Paul J.; Errington, Rachel J.

    2009-02-01

    The technical objective of this study has been to design, build and validate biocompatible hollow fiber implants based on fluorescence with integrated biophotonics components to enable in fiber kinetic cell based assays. A human osteosarcoma in vitro cell model fiber system has been established with validation studies to determine in fiber cell growth, cell cycle analysis and organization in normal and drug treated conditions. The rationale for implant development have focused on developing benchmark concepts in standard monolayer tissue culture followed by the development of in vitro hollow fiber designs; encompassing imaging with and without integrated biophotonics. Furthermore the effect of introducing targetable biosensors into the encapsulated tumor implant such as quantum dots for informing new detection readouts and possible implant designs have been evaluated. A preliminary micro/macro imaging approach has been undertaken, that could provide a mean to track distinct morphological changes in cells growing in a 3D matrix within the fiber which affect the light scattering properties of the implant. Parallel engineering studies have showed the influence of the optical properties of the fiber polymer wall in all imaging modes. Taken all together, we show the basic foundation and the opportunities for multi-modal imaging within an in vitro implant format.

  17. Effective fiber hypertrophy in satellite cell-depleted skeletal muscle

    PubMed Central

    McCarthy, John J.; Mula, Jyothi; Miyazaki, Mitsunori; Erfani, Rod; Garrison, Kelcye; Farooqui, Amreen B.; Srikuea, Ratchakrit; Lawson, Benjamin A.; Grimes, Barry; Keller, Charles; Van Zant, Gary; Campbell, Kenneth S.; Esser, Karyn A.; Dupont-Versteegden, Esther E.; Peterson, Charlotte A.

    2011-01-01

    An important unresolved question in skeletal muscle plasticity is whether satellite cells are necessary for muscle fiber hypertrophy. To address this issue, a novel mouse strain (Pax7-DTA) was created which enabled the conditional ablation of >90% of satellite cells in mature skeletal muscle following tamoxifen administration. To test the hypothesis that satellite cells are necessary for skeletal muscle hypertrophy, the plantaris muscle of adult Pax7-DTA mice was subjected to mechanical overload by surgical removal of the synergist muscle. Following two weeks of overload, satellite cell-depleted muscle showed the same increases in muscle mass (approximately twofold) and fiber cross-sectional area with hypertrophy as observed in the vehicle-treated group. The typical increase in myonuclei with hypertrophy was absent in satellite cell-depleted fibers, resulting in expansion of the myonuclear domain. Consistent with lack of nuclear addition to enlarged fibers, long-term BrdU labeling showed a significant reduction in the number of BrdU-positive myonuclei in satellite cell-depleted muscle compared with vehicle-treated muscle. Single fiber functional analyses showed no difference in specific force, Ca2+ sensitivity, rate of cross-bridge cycling and cooperativity between hypertrophied fibers from vehicle and tamoxifen-treated groups. Although a small component of the hypertrophic response, both fiber hyperplasia and regeneration were significantly blunted following satellite cell depletion, indicating a distinct requirement for satellite cells during these processes. These results provide convincing evidence that skeletal muscle fibers are capable of mounting a robust hypertrophic response to mechanical overload that is not dependent on satellite cells. PMID:21828094

  18. Effective fiber hypertrophy in satellite cell-depleted skeletal muscle.

    PubMed

    McCarthy, John J; Mula, Jyothi; Miyazaki, Mitsunori; Erfani, Rod; Garrison, Kelcye; Farooqui, Amreen B; Srikuea, Ratchakrit; Lawson, Benjamin A; Grimes, Barry; Keller, Charles; Van Zant, Gary; Campbell, Kenneth S; Esser, Karyn A; Dupont-Versteegden, Esther E; Peterson, Charlotte A

    2011-09-01

    An important unresolved question in skeletal muscle plasticity is whether satellite cells are necessary for muscle fiber hypertrophy. To address this issue, a novel mouse strain (Pax7-DTA) was created which enabled the conditional ablation of >90% of satellite cells in mature skeletal muscle following tamoxifen administration. To test the hypothesis that satellite cells are necessary for skeletal muscle hypertrophy, the plantaris muscle of adult Pax7-DTA mice was subjected to mechanical overload by surgical removal of the synergist muscle. Following two weeks of overload, satellite cell-depleted muscle showed the same increases in muscle mass (approximately twofold) and fiber cross-sectional area with hypertrophy as observed in the vehicle-treated group. The typical increase in myonuclei with hypertrophy was absent in satellite cell-depleted fibers, resulting in expansion of the myonuclear domain. Consistent with lack of nuclear addition to enlarged fibers, long-term BrdU labeling showed a significant reduction in the number of BrdU-positive myonuclei in satellite cell-depleted muscle compared with vehicle-treated muscle. Single fiber functional analyses showed no difference in specific force, Ca(2+) sensitivity, rate of cross-bridge cycling and cooperativity between hypertrophied fibers from vehicle and tamoxifen-treated groups. Although a small component of the hypertrophic response, both fiber hyperplasia and regeneration were significantly blunted following satellite cell depletion, indicating a distinct requirement for satellite cells during these processes. These results provide convincing evidence that skeletal muscle fibers are capable of mounting a robust hypertrophic response to mechanical overload that is not dependent on satellite cells.

  19. Integrating perovskite solar cells into a flexible fiber.

    PubMed

    Qiu, Longbin; Deng, Jue; Lu, Xin; Yang, Zhibin; Peng, Huisheng

    2014-09-22

    Perovskite solar cells have triggered a rapid development of new photovoltaic devices because of high energy conversion efficiencies and their all-solid-state structures. To this end, they are particularly useful for various wearable and portable electronic devices. Perovskite solar cells with a flexible fiber structure were now prepared for the first time by continuously winding an aligned multiwalled carbon nanotube sheet electrode onto a fiber electrode; photoactive perovskite materials were incorporated in between them through a solution process. The fiber-shaped perovskite solar cell exhibits an energy conversion efficiency of 3.3%, which remained stable on bending. The perovskite solar cell fibers may be woven into electronic textiles for large-scale application by well-developed textile technologies.

  20. High temperature battery cell comprising stress free hollow fiber bundle

    SciTech Connect

    Anand, J. N.; Revak, T. T.; Rossini, F. J.

    1985-04-16

    Thermal stressing of hollow fibers constituting the electrolyte-separator in a high temperature battery cell, and of certain other elements thereof, is avoided by suspending the assembly comprising the anolyte tank, the tube-sheet, the hollow fibers and a cathodic current collector-distributor within the casing and employing a limp connection between the collector-distributor and the cathode terminal of the cell.

  1. De-esterified Pectins in the Cell Walls of Cotton Fiber: A Study of Fiber Mutants

    USDA-ARS?s Scientific Manuscript database

    In the wild-type cotton (DP 5690), the cell walls of elongating cotton fibers are bilayered, with the outer layer enriched in de-esterified homogalacturonan (HGA), and an inner layer enriched in xyloglucans and cellulose. This bilayer is conspicuously absent in the cell walls of the ovule epidermal...

  2. Dynamics of Cancer Cell near Collagen Fiber Chain

    NASA Astrophysics Data System (ADS)

    Kim, Jihan; Sun, Bo

    Cell migration is an integrated process that is important in life. Migration is essential for embryonic development as well as homeostatic processes such as wound healing and immune responses. When cell migrates through connective extracellular matrix (ECM), it applies cellular traction force to ECM and senses the rigidity of their local environment. We used human breast cancer cell (MDA-MB-231) which is highly invasive and applies strong traction force to ECM. As cancer cell applies traction force to type I collage-based ECM, it deforms collagen fibers near the surface. Patterns of deforming collagen fibers are significantly different with pairs of cancer cells compared to a single cancer cell. While a pair of cancer cells within 60 um creates aligned collagen fiber chains between them permanently, a single cancer cell does not form any fiber chains. In this experiment we measured a cellular response and an interaction between a pair of cells through the chain. Finally, we analyzed correlation of directions between cancer cell migration and the collagen chain alignment.

  3. Regulation of auxin on secondary cell wall cellulose biosynthesis in developing cotton fibers

    USDA-ARS?s Scientific Manuscript database

    Cotton (Gossypium hirsutum L.) fibers are unicellular trichomes that differentiate from epidermal cells of developing cotton ovules. Mature fibers exhibit thickened secondary walls composed of nearly pure cellulose. Cotton fiber development is divided into four overlapping phases, 1) initiation sta...

  4. Titanium diboride ceramic fiber composites for Hall-Heroult cells

    DOEpatents

    Besmann, Theodore M.; Lowden, Richard A.

    1990-01-01

    An improved cathode structure for Hall-Heroult cells for the electrolytic production of aluminum metal. This cathode structure is a preform fiber base material that is infiltrated with electrically conductive titanium diboride using chemical vapor infiltration techniques. The structure exhibits good fracture toughness, and is sufficiently resistant to attack by molten aluminum. Typically, the base can be made from a mat of high purity silicon carbide fibers. Other ceramic or carbon fibers that do not degrade at temperatures below about 1000 deg. C can be used.

  5. Titanium diboride ceramic fiber composites for Hall-Heroult cells

    DOEpatents

    Besmann, T.M.; Lowden, R.A.

    1990-05-29

    An improved cathode structure is described for Hall-Heroult cells for the electrolytic production of aluminum metal. This cathode structure is a preform fiber base material that is infiltrated with electrically conductive titanium diboride using chemical vapor infiltration techniques. The structure exhibits good fracture toughness, and is sufficiently resistant to attack by molten aluminum. Typically, the base can be made from a mat of high purity silicon carbide fibers. Other ceramic or carbon fibers that do not degrade at temperatures below about 1000 C can be used.

  6. Multi-scale undulations in human aortic endothelial cell fibers.

    PubMed

    Frketic, Jolie B; DeLaPeña, Abigail; Suaris, Melanie G; Zehnder, Steven M; Angelini, Thomas E

    2015-02-01

    Blood vessels often have an undulatory morphology, with excessive bending, kinking, and coiling occuring in diseased vasculature. The underlying physical causes of these morphologies are generally attributed, in combination, to changes in blood pressure, blood flow rate, and cell proliferation or apoptosis. However, pathological vascular morphologies often start during developmental vasculogenesis. At early stages of vasculogenesis, angioblasts (vascular endothelial cells that have not formed a lumen) assemble into primitive vessel-like fibers before blood flow occurs. If loose, fibrous aggregates of endothelial cells can generate multi-cellular undulations through mechanical instabilities, driven by the cytoskeleton, new insight into vasculature morphology may be achieved with simple in vitro models of endothelial cell fibers. Here we study mechanical instabilities in vessel-like structures made from endothelial cells embedded in a collagen matrix. We find that endothelial cell fibers contract radially over time, and undulate at two dominant wavelengths: approximately 1cm and 1mm. Simple mechanical models suggest that the long-wavelength undulation is Euler buckling in rigid confinement, while the short-wavelength buckle may arise from a mismatch between fiber bending energy and matrix deformation. These results suggest a combination of fiber-like geometry, cystoskeletal contractions, and extracellular matrix elasticity may contribute to undulatory blood vessel morphology in the absence of a lumen or blood pressure.

  7. Cell counting system by using single fiber interferometer

    NASA Astrophysics Data System (ADS)

    Lee, Seung Seok; Kim, Joo Ha; Choi, Eun Seo

    2017-02-01

    We proposed a cell-counting method using optical fiber interferometer and demonstrated the performance of the proposed method. The cell counting means the counting or the quantification of individual cells. Its application ranges from the biological research to practical disease diagnosis. As a conventional approach for cell counting, various methods are employed. Among them, flow cytometry is quite accurate and exact method but it uses bulk and expensive optical equipment. When image-based methods are exploited, the limited field of view obtained by microscope is considered for cell counting. From this reason, problem of time consuming for whole cell counting is to be solved. The proposed method utilized single-mode optical fiber and high-speed spectrometer. Light beam having broad spectral bandwidth over 100 nm at 850-nm central wavelength is irradiated to a flow channel through fiber from top to bottom. Different optical path length differences are made whether the cell is passing though the flow channel across the beam area or not. The difference of optical path lengths in the beam area due to the cell induces interference signal depending on optical thickness of the cell. By measuring a series of interferences, the number of cells can be analyzed. The proposed system can be implemented without any expensive and perform the cell counting in the absence of complex image analysis. Interferometer-based cell counting can be a good alternative to the reported cell-counting methods.

  8. Cell-autonomous requirements for Dlg-1 for lens epithelial cell structure and fiber cell morphogenesis.

    PubMed

    Rivera, Charlene; Yamben, Idella F; Shatadal, Shalini; Waldof, Malinda; Robinson, Michael L; Griep, Anne E

    2009-09-01

    Cell polarity and adhesion are thought to be key determinants in organismal development. In Drosophila, discs large (dlg) has emerged as an important regulator of epithelial cell proliferation, adhesion, and polarity. Herein, we investigated the role of the mouse homolog of dlg (Dlg-1) in the development of the mouse ocular lens. Tissue-specific ablation of Dlg-1 throughout the lens early in lens development led to an expansion and disorganization of the epithelium that correlated with changes in the distribution of adhesion and polarity factors. In the fiber cells, differentiation defects were observed. These included alterations in cell structure and the disposition of cell adhesion/cytoskeletal factors, delay in denucleation, and reduced levels of alpha-catenin, pERK1/2, and MIP26. These fiber cell defects were recapitulated when Dlg-1 was disrupted only in fiber cells. These results suggest that Dlg-1 acts in a cell autonomous manner to regulate epithelial cell structure and fiber cell differentiation.

  9. CHARACTERIZATION OF ALVEOLAR EPITHELIAL CELLS CULTURED IN SEMIPERMEABLE HOLLOW FIBERS

    PubMed Central

    Grek, Christina L.; Newton, Danforth A.; Qiu, Yonhzhi; Wen, Xuejun; Spyropoulos, Demetri D.; Baatz, John E.

    2012-01-01

    Cell culture methods commonly used to represent alveolar epithelial cells in vivo have lacked airflow, a 3-dimensional air-liquid interface, and dynamic stretching characteristics of native lung tissue—physiological parameters critical for normal phenotypic gene expression and cellular function. Here the authors report the development of a selectively semipermeable hollow fiber culture system that more accurately mimics the in vivo microenvironment experienced by mammalian distal airway cells than in conventional or standard air-liquid interface culture. Murine lung epithelial cells (MLE-15) were cultured within semipermeable polyurethane hollow fibers and introduced to controlled airflow through the microfiber interior. Under these conditions, MLE-15 cells formed confluent monolayers, demonstrated a cuboidal morphology, formed tight junctions, and produced and secreted surfactant proteins. Numerous lamellar bodies and microvilli were present in MLE-15 cells grown in hollow fiber culture. Conversely, these alveolar type II cell characteristics were reduced in MLE-15 cells cultured in conventional 2D static culture systems. These data support the hypothesis that MLE-15 cells grown within our microfiber culture system in the presence of airflow maintain the phenotypic characteristics of type II cells to a higher degree than those grown in standard in vitro cell culture models. Application of our novel model system may prove advantageous for future studies of specific gene and protein expression involving alveolar epithelial or bronchiolar epithelial cells. PMID:19263283

  10. Dual fiber microprobe for mapping elemental distributions in biological cells

    DOEpatents

    Martin, Rodger C [Powell, TN; Martin, Madhavi Z [Powell, TN

    2007-07-31

    Laser-induced breakdown spectroscopy (LIBS) is applied on a microscale for in situ elemental analysis and spatial mapping in biological cells. A high power laser beam is focused onto a cell surface using a dual branching optical fiber probe for optical excitation of the cell constituents. Dual spectrometers and ICCD detectors capture the emission spectra from the excited cell(s). Repeated probing or repositioning of the laser beam with respect to the cell can provide 2-D or 3-D mapping of the cell.

  11. Proteomics and Phosphoproteomics Analysis of Human Lens Fiber Cell Membranes

    PubMed Central

    Wang, Zhen; Han, Jun; David, Larry L.; Schey, Kevin L.

    2013-01-01

    Purpose. The human lens fiber cell insoluble membrane fraction contains important membrane proteins, cytoskeletal proteins, and cytosolic proteins that are strongly associated with the membrane. The purpose of this study was to characterize the lens fiber cell membrane proteome and phosphoproteome from human lenses. Methods. HPLC-mass spectrometry–based multidimensional protein identification technology (MudPIT), without or with phosphopeptide enrichment, was applied to study the proteome and phosphoproteome of lens fiber cell membranes, respectively. Results. In total, 951 proteins were identified, including 379 integral membrane and membrane-associated proteins. Enriched gene categories and pathways based on the proteomic analysis include carbohydrate metabolism (glycolysis/gluconeogenesis, pentose phosphate pathway, pyruvate metabolism), proteasome, cell-cell signaling and communication (GTP binding, gap junction, focal adhesion), glutathione metabolism, and actin regulation. The combination of TiO2 phosphopeptide enrichment and MudPIT analysis revealed 855 phosphorylation sites on 271 proteins, including 455 phosphorylation sites that have not been previously identified. PKA, PKC, CKII, p38MAPK, and RSK are predicted as the major kinases for phosphorylation on the sites identified in the human lens membrane fraction. Conclusions. The results presented herein significantly expand the characterized proteome and phosphoproteome of the human lens fiber cell and provide a valuable reference for future research in studies of lens development and disease. PMID:23349431

  12. Polymer Solar Cells: Solubility Controls Fiber Network Formation.

    PubMed

    van Franeker, Jacobus J; Heintges, Gaël H L; Schaefer, Charley; Portale, Giuseppe; Li, Weiwei; Wienk, Martijn M; van der Schoot, Paul; Janssen, René A J

    2015-09-16

    The photoactive layer of polymer solar cells is commonly processed from a four-component solution, containing a semiconducting polymer and a fullerene derivative dissolved in a solvent-cosolvent mixture. The nanoscale dimensions of the polymer-fullerene morphology that is formed upon drying determines the solar cell performance, but the fundamental processes that govern the size of the phase-separated polymer and fullerene domains are poorly understood. Here, we investigate morphology formation of an alternating copolymer of diketopyrrolopyrrole and a thiophene-phenyl-thiophene oligomer (PDPPTPT) with relatively long 2-decyltetradecyl (DT) side chains blended with [6,6]-phenyl-C71-butyric acid methyl ester. During solvent evaporation the polymer crystallizes into a fibrous network. The typical width of these fibers is analyzed by quantification of transmission electron microscopic images, and is mainly determined by the solubility of the polymer in the cosolvent and the molecular weight of the polymer. A higher molecular weight corresponds to a lower solubility and film processing results in a smaller fiber width. Surprisingly, the fiber width is not related to the drying rate or the amount of cosolvent. We have made solar cells with fiber widths ranging from 28 to 68 nm and found an inverse relation between fiber width and photocurrent. Finally, by mixing two cosolvents, we develop a ternary solvent system to tune the fiber width. We propose a model based on nucleation-and-growth which can explain these measurements. Our results show that the width of the semicrystalline polymer fibers is not the result of a frozen dynamical state, but determined by the nucleation induced by the polymer solubility.

  13. Dedifferentiated fat cells differentiate into osteoblasts in titanium fiber mesh.

    PubMed

    Kishimoto, Naotaka; Momota, Yoshihiro; Hashimoto, Yoshiya; Ando, Kayoko; Omasa, Takeshi; Kotani, Junichiro

    2013-01-01

    Mature adipocyte-derived dedifferentiated fat (DFAT) cells rapidly differentiate into osteoblasts under three-dimensional culture conditions. However, it has not been demonstrated that DFAT cells can differentiate into osteoblasts in a rigid scaffold consisting of titanium fiber mesh (TFM). We examined the proliferation and osteogenic differentiation ability of DFAT cells using TFM as a scaffold. DFAT cells derived from rabbit subcutaneous fat were seeded into TFM and cultured in osteogenic medium containing dexamethasone, L-ascorbic acid 2-phosphate and β-glycerophosphate for 14 days. In scanning electron microscopy (SEM) analysis, well-spread cells covered the titanium fibers on day 3, and appeared to increase in number from day 3 to 7. Numerous globular accretions were found and almost completely covered the fibers on day 14. Cell proliferation, as measured by DNA content in the TFM, was significantly higher on day 7 compared with that of day 1. Osteocalcin and calcium content in the TFM were significantly higher on day 14 compared to those of days 1, 3, and 7, indicating DFAT cells differentiated into osteoblasts. We theorize that globular accretions observed in SEM analysis may be calcified matrix resulting from osteocalcin secreted by osteoblasts binding calcium contained in fetal bovine serum. In this study, we demonstrated that DFAT cells differentiate into osteoblasts and deposit mineralized matrices in TFM. Therefore, the combination of DFAT cells and TFM may be an attractive option for bone tissue engineering.

  14. New insights into the signal transmission from taste cells to gustatory nerve fibers.

    PubMed

    Yoshida, Ryusuke; Ninomiya, Yuzo

    2010-01-01

    Taste receptor cells detect chemical compounds in the oral cavity and transfer their messages to gustatory afferent nerve fibers. Considering the coding of taste information, the sensitivity of taste cells and the connection between taste cells and gustatory fibers may be critical in this process. Broadly tuned taste cells and random connections between taste cells and fibers would produce gustatory fibers that have broad sensitivity to multiple taste qualities. Narrowly tuned taste cells and selective connections would yield gustatory nerve fibers that respond to specific taste quality. This review summarizes results showing molecular and morphological aspects of taste bud cells, physiological responses of taste cells, possible connections between taste cells and gustatory fibers, and transmitter release from taste cells, and discusses how taste qualities are encoded among taste bud cells and how taste information is transmitted from taste cells to gustatory nerve fibers. Copyright 2010 Elsevier Inc. All rights reserved.

  15. Satellite cell depletion prevents fiber hypertrophy in skeletal muscle.

    PubMed

    Egner, Ingrid M; Bruusgaard, Jo C; Gundersen, Kristian

    2016-08-15

    The largest mammalian cells are the muscle fibers, and they have multiple nuclei to support their large cytoplasmic volumes. During hypertrophic growth, new myonuclei are recruited from satellite stem cells into the fiber syncytia, but it was recently suggested that such recruitment is not obligatory: overload hypertrophy after synergist ablation of the plantaris muscle appeared normal in transgenic mice in which most of the satellite cells were abolished. When we essentially repeated these experiments analyzing the muscles by immunohistochemistry and in vivo and ex vivo imaging, we found that overload hypertrophy was prevented in the satellite cell-deficient mice, in both the plantaris and the extensor digitorum longus muscles. We attribute the previous findings to a reliance on muscle mass as a proxy for fiber hypertrophy, and to the inclusion of a significant number of regenerating fibers in the analysis. We discuss that there is currently no model in which functional, sustainable hypertrophy has been unequivocally demonstrated in the absence of satellite cells; an exception is re-growth, which can occur using previously recruited myonuclei without addition of new myonuclei. © 2016. Published by The Company of Biologists Ltd.

  16. Carbon fiber enhanced bioelectricity generation in soil microbial fuel cells.

    PubMed

    Li, Xiaojing; Wang, Xin; Zhao, Qian; Wan, Lili; Li, Yongtao; Zhou, Qixing

    2016-11-15

    The soil microbial fuel cell (MFC) is a promising biotechnology for the bioelectricity recovery as well as the remediation of organics contaminated soil. However, the electricity production and the remediation efficiency of soil MFC are seriously limited by the tremendous internal resistance of soil. Conductive carbon fiber was mixed with petroleum hydrocarbons contaminated soil and significantly enhanced the performance of soil MFC. The maximum current density, the maximum power density and the accumulated charge output of MFC mixed carbon fiber (MC) were 10, 22 and 16 times as high as those of closed circuit control due to the carbon fiber productively assisted the anode to collect the electron. The internal resistance of MC reduced by 58%, 83% of which owed to the charge transfer resistance, resulting in a high efficiency of electron transfer from soil to anode. The degradation rates of total petroleum hydrocarbons enhanced by 100% and 329% compared to closed and opened circuit controls without the carbon fiber respectively. The effective range of remediation and the bioelectricity recovery was extended from 6 to 20cm with the same area of air-cathode. The mixed carbon fiber apparently enhanced the bioelectricity generation and the remediation efficiency of soil MFC by means of promoting the electron transfer rate from soil to anode. The use of conductively functional materials (e.g. carbon fiber) is very meaningful for the remediation and bioelectricity recovery in the bioelectrochemical remediation.

  17. Oxide Fiber Cathode Materials for Rechargeable Lithium Cells

    NASA Technical Reports Server (NTRS)

    Rice, Catherine E.; Welker, Mark F.

    2008-01-01

    LiCoO2 and LiNiO2 fibers have been investigated as alternatives to LiCoO2 and LiNiO2 powders used as lithium-intercalation compounds in cathodes of rechargeable lithium-ion electrochemical cells. In making such a cathode, LiCoO2 or LiNiO2 powder is mixed with a binder [e.g., poly(vinylidene fluoride)] and an electrically conductive additive (usually carbon) and the mixture is pressed to form a disk. The binder and conductive additive contribute weight and volume, reducing the specific energy and energy density, respectively. In contrast, LiCoO2 or LiNiO2 fibers can be pressed and sintered to form a cathode, without need for a binder or a conductive additive. The inter-grain contacts of the fibers are stronger and have fewer defects than do those of powder particles. These characteristics translate to increased flexibility and greater resilience on cycling and, consequently, to reduced loss of capacity from cycle to cycle. Moreover, in comparison with a powder-based cathode, a fiber-based cathode is expected to exhibit significantly greater ionic and electronic conduction along the axes of the fibers. Results of preliminary charge/discharge-cycling tests suggest that energy densities of LiCoO2- and LiNiO2-fiber cathodes are approximately double those of the corresponding powder-based cathodes.

  18. Tropomodulin 1 Constrains Fiber Cell Geometry during Elongation and Maturation in the Lens Cortex

    PubMed Central

    Nowak, Roberta B.

    2012-01-01

    Lens fiber cells exhibit a high degree of hexagonal packing geometry, determined partly by tropomodulin 1 (Tmod1), which stabilizes the spectrin-actin network on lens fiber cell membranes. To ascertain whether Tmod1 is required during epithelial cell differentiation to fiber cells or during fiber cell elongation and maturation, the authors quantified the extent of fiber cell disorder in the Tmod1-null lens and determined locations of disorder by confocal microscopy and computational image analysis. First, nearest neighbor analysis of fiber cell geometry in Tmod1-null lenses showed that disorder is confined to focal patches. Second, differentiating epithelial cells at the equator aligned into ordered meridional rows in Tmod1-null lenses, with disordered patches first observed in elongating fiber cells. Third, as fiber cells were displaced inward in Tmod1-null lenses, total disordered area increased due to increased sizes (but not numbers) of individual disordered patches. The authors conclude that Tmod1 is required first to coordinate fiber cell shapes and interactions during tip migration and elongation and second to stabilize ordered fiber cell geometry during maturation in the lens cortex. An unstable spectrin-actin network without Tmod1 may result in imbalanced forces along membranes, leading to fiber cell rearrangements during elongation, followed by propagation of disorder as fiber cells mature. PMID:22473940

  19. Fibrin-fiber architecture influences cell spreading and differentiation

    PubMed Central

    Bruekers, Stéphanie M. C.; Jaspers, Maarten; Hendriks, José M. A.; Kurniawan, Nicholas A.; Koenderink, Gijsje H.; Kouwer, Paul H. J.; Rowan, Alan E.; T. S. Huck, Wilhelm

    2016-01-01

    ABSTRACT The mechanical and structural properties of the extracellular matrix (ECM) play an important role in regulating cell fate. The natural ECM has a complex fibrillar structure and shows nonlinear mechanical properties, which are both difficult to mimic synthetically. Therefore, systematically testing the influence of ECM properties on cellular behavior is very challenging. In this work we show two different approaches to tune the fibrillar structure and mechanical properties of fibrin hydrogels. Addition of extra thrombin before gelation increases the protein density within the fibrin fibers without significantly altering the mechanical properties of the resulting hydrogel. On the other hand, by forming a composite hydrogel with a synthetic biomimetic polyisocyanide network the protein density within the fibrin fibers decreases, and the mechanics of the composite material can be tuned by the PIC/fibrin mass ratio. The effect of the changes in gel structure and mechanics on cellular behavior are investigated, by studying human mesenchymal stem cell (hMSC) spreading and differentiation on these gels. We find that the trends observed in cell spreading and differentiation cannot be explained by the bulk mechanics of the gels, but correlate to the density of the fibrin fibers the gels are composed of. These findings strongly suggest that the microscopic properties of individual fibers in fibrous networks play an essential role in determining cell behavior. PMID:26910190

  20. Pax6 is essential for lens fiber cell differentiation.

    PubMed

    Shaham, Ohad; Smith, April N; Robinson, Michael L; Taketo, Makoto M; Lang, Richard A; Ashery-Padan, Ruth

    2009-08-01

    The developing ocular lens provides an excellent model system with which to study the intrinsic and extrinsic cues governing cell differentiation. Although the transcription factors Pax6 and Sox2 have been shown to be essential for lens induction, their later roles during lens fiber differentiation remain largely unknown. Using Cre/loxP mutagenesis, we somatically inactivated Pax6 and Sox2 in the developing mouse lens during differentiation of the secondary lens fibers and explored the regulatory interactions of these two intrinsic factors with the canonical Wnt pathway. Analysis of the Pax6-deficient lenses revealed a requirement for Pax6 in cell cycle exit and differentiation into lens fiber cells. In addition, Pax6 disruption led to apoptosis of lens epithelial cells. We show that Pax6 regulates the Wnt antagonist Sfrp2 in the lens, and that Sox2 expression is upregulated in the Pax6-deficient lenses. However, our study demonstrates that the failure of differentiation following loss of Pax6 is independent of beta-catenin signaling or Sox2 activity. This study reveals that Pax6 is pivotal for initiation of the lens fiber differentiation program in the mammalian eye.

  1. Fibrin-fiber architecture influences cell spreading and differentiation.

    PubMed

    Bruekers, Stéphanie M C; Jaspers, Maarten; Hendriks, José M A; Kurniawan, Nicholas A; Koenderink, Gijsje H; Kouwer, Paul H J; Rowan, Alan E; T S Huck, Wilhelm

    2016-09-02

    The mechanical and structural properties of the extracellular matrix (ECM) play an important role in regulating cell fate. The natural ECM has a complex fibrillar structure and shows nonlinear mechanical properties, which are both difficult to mimic synthetically. Therefore, systematically testing the influence of ECM properties on cellular behavior is very challenging. In this work we show two different approaches to tune the fibrillar structure and mechanical properties of fibrin hydrogels. Addition of extra thrombin before gelation increases the protein density within the fibrin fibers without significantly altering the mechanical properties of the resulting hydrogel. On the other hand, by forming a composite hydrogel with a synthetic biomimetic polyisocyanide network the protein density within the fibrin fibers decreases, and the mechanics of the composite material can be tuned by the PIC/fibrin mass ratio. The effect of the changes in gel structure and mechanics on cellular behavior are investigated, by studying human mesenchymal stem cell (hMSC) spreading and differentiation on these gels. We find that the trends observed in cell spreading and differentiation cannot be explained by the bulk mechanics of the gels, but correlate to the density of the fibrin fibers the gels are composed of. These findings strongly suggest that the microscopic properties of individual fibers in fibrous networks play an essential role in determining cell behavior.

  2. Electrospun fiber membranes enable proliferation of genetically modified cells

    PubMed Central

    Borjigin, Mandula; Eskridge, Chris; Niamat, Rohina; Strouse, Bryan; Bialk, Pawel; Kmiec, Eric B

    2013-01-01

    Polycaprolactone (PCL) and its blended composites (chitosan, gelatin, and lecithin) are well-established biomaterials that can enrich cell growth and enable tissue engineering. However, their application in the recovery and proliferation of genetically modified cells has not been studied. In the study reported here, we fabricated PCL-biomaterial blended fiber membranes, characterized them using physicochemical techniques, and used them as templates for the growth of genetically modified HCT116-19 colon cancer cells. Our data show that the blended polymers are highly miscible and form homogenous electrospun fiber membranes of uniform texture. The aligned PCL nanofibers support robust cell growth, yielding a 2.5-fold higher proliferation rate than cells plated on standard plastic plate surfaces. PCL-lecithin fiber membranes yielded a 2.7-fold higher rate of proliferation, while PCL-chitosan supported a more modest growth rate (1.5-fold higher). Surprisingly, PCL-gelatin did not enhance cell proliferation when compared to the rate of cell growth on plastic surfaces. PMID:23467983

  3. Mammalian cell and protein distributions in ultrafiltration hollow fiber bioreactors.

    PubMed

    Piret, J M; Cooney, C L

    1990-11-01

    The heterogeneous nature of hollow fiber reactors for cell cultivation requires special considerations for proper design and operation. Downstream concentration of high-molecular-weight proteins has been measured in the shell side of ultrafiltration hollow fiber bioreactors. This distribution resulted from shell-side convective fluxes which caused a concentration polarization of proteins retained by the ultrafiltration membranes (nominal 3 x 10(4) D cutoff). Measurements of the axial hybridoma cell distribution also revealed a downstream concentration of viable cells during the first month of perfusion operation. This is believed to result from the shell-side convective flow and its influence on the inoculum and high-molecular-weight growth factor distributions. The heterogeneous distribution of cells leads to reduced cell numbers and reactor productivities. The mechanisms responsible for these phenomena have been investigated and their implications in process design and operation are considered. The heterogeneous protein and cell distributions on the shell side of hollow fiber bioreactors have been reduced significantly by periodic alternation of the direction of recycle flow and the reactor antibody productivities have been doubled.

  4. Morphological studies on the culture of kidney epithelial cells in a fiber-in-fiber bioreactor design with hollow fiber membranes.

    PubMed

    Fey-Lamprecht, F; Albrecht, W; Groth, T; Weigel, T; Gross, U

    2003-05-01

    A hollow fiber-in-fiber-based bioreactor system was tested for the applicability to host kidney epithelial cells as a model system for a bioartificial kidney. Hollow fibers were prepared from polyacrylonitrile (PAN), polysulfone-polyvinylpyrollidinone (PVP) blend (PSU) and poly(acrylonitrile-N-vinylpyrollidinone) copolymer P(AN-NVP). Hollow fibers with smaller and larger diameters were prepared so that the smaller fitted into the larger, with a distance of 50-100 microm in between. The following material combinations as outer and inner fiber were applied: PAN-PAN; PSU-PSU, PSU-P(AN-NVP). Madin-Darby kidney epithelial cells (MDCK) were seeded in the interfiber space and cultured for a period up to 14 days. Light, scanning, and transmission electron microscopy were used to follow the adhesion and growth of cells, and to characterize their morphology. As a result, we found that MDCK cells were able to grow in the interfiber space in mono- and multilayers without signs of systemic degeneration. Comparison of the different materials showed that PAN and P(AN-NVP) provided the best growth conditions, indicated by a tight attachment of cells on hollow fiber membrane, and subsequent proliferation and development of structural elements of normal epithelia, such as tight junctions and microvilli. In conclusion, the fiber-in-fiber design seems to be an interesting system for the construction of a bioartificial kidney. Copyright 2003 Wiley Periodicals, Inc.

  5. The pattern of cell wall deterioration in lignocellulose fibers throughout enzymatic cellulose hydrolysis.

    PubMed

    Li, Xinping; Clarke, Kimberley; Li, Kecheng; Chen, Aicheng

    2012-01-01

    Cell wall deterioration throughout enzymatic hydrolysis of cellulosic biomass is greatly affected by the chemical composition and the ultrastructure of the fiber cell wall. The resulting pattern of cell wall deterioration will reveal information on cellulose activity throughout enzymatic hydrolysis. This study investigates the progression and morphological changes in lignocellulose fibers throughout enzymatic hydrolysis, using (transmission electron microscopy) TEM and field emission scanning electron microscopy (FE-SEM). Softwood thermo-mechanical pulp (STMP) and softwood bleached kraft pulp (SBKP), lignocellulose substrates containing almost all the original fiber composition, and with lignin and some hemicellulose removed, respectively, was compared for morphology changes throughout hydrolysis. The difference of conversion between STMP and SBKP after 48 h of enzymatic hydrolysis is 11 and 88%, respectively. TEM images revealed an even fiber cell wall cross section density, with uneven middle lamella coverage in STMP fibers. SKBP fibers exhibited some spaces between cell wall and lamella layers due to the removal of lignin and some hemicellulose. After 1 h hydrolysis in SBKP fibers, there were more changes in the fiber cross-sectional area than after 10 h hydrolysis in STMP fibers. Cell wall degradation was uneven, and originated in accessible cellulose throughout the fiber cell wall. FE-SEM images illustrated more morphology changes in SBKP fibers than STMP fibers. Enzymatic action of STMP fiber resulted in a smoother fiber surface, along with fiber peeling and the formation of ribbon-disjunction layers. SBKP fibers exhibited structural changes such as fiber erosion, fiber cutting, and fiber splitting throughout enzymatic hydrolysis.

  6. Fiber

    MedlinePlus

    ... 2016:chap 213. National Research Council. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). The National Academies Press. ...

  7. Neuregulin 1 functionalization of organic fibers for Schwann cell guidance

    NASA Astrophysics Data System (ADS)

    Tonazzini, Ilaria; Moffa, Maria; Pisignano, Dario; Cecchini, Marco

    2017-04-01

    The repair of peripheral nerve lesions is a clinical problem where the functional recovery is often far from being satisfactory, although peripheral nerves generally retain good potential for regeneration. Here, we develop a novel scaffold approach based on bioactive fibers of poly(ε-caprolactone) where nanotopographical guidance and neuregulin 1 (NRG1) cues are combined. We interface them with rat primary Schwann cells (SCs), the peripheral glial cells that drive initial regeneration of injured nerves, and found that the combination of NRG1 with parallel nano-fibrous topographies is effective in improving SC growth up to 72 h, alignment to fiber topography, and bipolar differentiation, opening original perspectives for nerve repair applications.

  8. Fiber-laser-based photoacoustic microscopy and melanoma cell detection

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Maslov, Konstantin; Zhang, Yu; Hu, Song; Yang, Lihmei; Xia, Younan; Liu, Jian; Wang, Lihong V.

    2011-01-01

    For broad applications in biomedical research involving functional dynamics and clinical studies, a photoacoustic microscopy system should be compact, stable, and fast. In this work, we use a fiber laser as the photoacoustic irradiation source to meet these goals. The laser system measures 45×56×13 cm3. The stability of the laser is attributed to the intrinsic optical fiber-based light amplification and output coupling. Its 50-kHz pulse repetition rate enables fast scanning or extensive signal averaging. At the laser wavelength of 1064 nm, the photoacoustic microscope still has enough sensitivity to image small blood vessels while providing high optical absorption contrast between melanin and hemoglobin. Label-free melanoma cells in flowing bovine blood are imaged in vitro, yielding measurements of both cell size and flow speed.

  9. Chromatin Degradation in Differentiating Fiber Cells of the Eye Lens

    PubMed Central

    Bassnett, Steven; Mataic, Danijela

    1997-01-01

    During development, the lens of the eye becomes transparent, in part because of the elimination of nuclei and other organelles from the central lens fiber cells by an apoptotic-like mechanism. Using confocal microscopy we showed that, at the border of the organelle-free zone (OFZ), fiber cell nuclei became suddenly irregular in shape, with marginalized chromatin. Subsequently, holes appeared in the nuclear envelope and underlying laminae, and the nuclei collapsed into condensed, spherical structures. Nuclear remnants, containing DNA, histones, lamin B2, and fragments of nuclear membrane, were detected deep in the OFZ. We used in situ electrophoresis to demonstrate that fragmented DNA was present only in cells bordering the OFZ. Confocal microscopy of terminal deoxynucleotidyl transferase (TdT)–labeled lens slices confirmed that DNA fragmentation was a relatively late event in fiber differentiation, occurring after the loss of the nuclear membrane. DNA fragments with 3′-OH or 3′-PO4 ends were not observed elsewhere in the lens under normal conditions, although they could be produced by pretreatment with DNase I or micrococcal nuclease, respectively. Dual labeling with TdT and an antibody against protein disulfide isomerase, an ER-resident protein, revealed a distinct spatial and temporal gap between the disappearance of ER and nuclear membranes and the onset of DNA degradation. Thus, fiber cell chromatin disassembly differs significantly from classical apoptosis, in both the sequence of events and the time course of the process. The fact that DNA degradation occurs only after the disappearance of mitochondrial, ER, and nuclear membranes suggests that damage to intracellular membranes may be an initiating event in nuclear breakdown. PMID:9105035

  10. Hollow fibers - Their applications to the study of mammalian cell function

    NASA Technical Reports Server (NTRS)

    Hymer, W. C.; Angeline, M.; Harkness, J.; Chu, M.; Grindleland, R.

    1984-01-01

    The use of hollow fiber technology in cell culture and transplantation is examined. The morphologies of encapsulated pituitary cells before and after implantation into the rat are defined. Implantation experiments using hollow fibers to study mammalian cell functions are described. Consideration is given to examining somatotroph, prolactin, prostrate, fibroblast, and retinal cell functions. These experiments demonstrate that hollow fiber technology is applicable for studying mammalian cell functions.

  11. Microintegrating smooth muscle cells into a biodegradable, elastomeric fiber matrix.

    PubMed

    Stankus, John J; Guan, Jianjun; Fujimoto, Kazuro; Wagner, William R

    2006-02-01

    Electrospinning permits fabrication of biodegradable elastomers into matrices that can resemble the scale and mechanical behavior of the native extracellular matrix. However, achieving high-cellular density and infiltration with this technique remains challenging and time consuming. We have overcome this limitation by electrospraying vascular smooth muscle cells (SMCs) concurrently with electrospinning a biodegradable, elastomeric poly(ester urethane)urea (PEUU). Trypan blue staining revealed no significant decrease in cell viability from the fabrication process and electrosprayed SMCs spread and proliferated similar to control unprocessed SMCs. The resulting SMC microintegrated PEUU constructs were cultured under static conditions or transmural perfusion. Higher cell numbers resulted with perfusion culture with 131% and 98% more viable cells versus static culture at days 4 and 7 (p<0.05). Fluorescent imaging and hematoxylin and eosin staining further illustrated high cell densities integrated between the elastomeric fibers after perfusion culture. SMC microintegrated PEUU was strong, flexible and anisotropic with tensile strengths ranging from 2.0 to 6.5 MPa and breaking strains from 850 to 1,700% dependent on the material axis. The ability to microintegrate smooth muscle or other cell types into a biodegradable elastomer fiber matrix embodies a novel tissue engineering approach that could be applied to fabricate high cell density elastic tissue mimetics, blood vessels or other cardiovascular tissues.

  12. Microintegrating smooth muscle cells into a biodegradable, elastomeric fiber matrix

    PubMed Central

    Stankus, John J.; Guan, Jianjun; Fujimoto, Kazuro; Wagner, William R.

    2010-01-01

    Electrospinning permits fabrication of biodegradable elastomers into matrices that can resemble the scale and mechanical behavior of the native extracellular matrix. However, achieving high-cellular density and infiltration with this technique remains challenging and time consuming. We have overcome this limitation by electrospraying vascular smooth muscle cells (SMCs) concurrently with electrospinning a biodegradable, elastomeric poly(ester urethane)urea (PEUU). Trypan blue staining revealed no significant decrease in cell viability from the fabrication process and electrosprayed SMCs spread and proliferated similar to control unprocessed SMCs. The resulting SMC microintegrated PEUU constructs were cultured under static conditions or transmural perfusion. Higher cell numbers resulted with perfusion culture with 131% and 98% more viable cells versus static culture at days 4 and 7 (p < 0.05). Fluorescent imaging and hematoxylin and eosin staining further illustrated high cell densities integrated between the elastomeric fibers after perfusion culture. SMC microintegrated PEUU was strong, flexible and anisotropic with tensile strengths ranging from 2.0 to 6.5 MPa and breaking strains from 850 to 1700% dependent on the material axis. The ability to microintegrate smooth muscle or other cell types into a biodegradable elastomer fiber matrix embodies a novel tissue engineering approach that could be applied to fabricate high cell density elastic tissue mimetics, blood vessels or other cardiovascular tissues. PMID:16095685

  13. Flexible and dynamic nucleosome fiber in living mammalian cells.

    PubMed

    Nozaki, Tadasu; Kaizu, Kazunari; Pack, Chan-Gi; Tamura, Sachiko; Tani, Tomomi; Hihara, Saera; Nagai, Takeharu; Takahashi, Koichi; Maeshima, Kazuhiro

    2013-01-01

    Genomic DNA is organized three dimensionally within cells as chromatin and is searched and read by various proteins by an unknown mechanism; this mediates diverse cell functions. Recently, several pieces of evidence, including our cryomicroscopy and synchrotron X-ray scattering analyses, have demonstrated that chromatin consists of irregularly folded nucleosome fibers without a 30-nm chromatin fiber (i.e., a polymer melt-like structure). This melt-like structure implies a less physically constrained and locally more dynamic state, which may be crucial for protein factors to scan genomic DNA. Using a combined approach of fluorescence correlation spectroscopy, Monte Carlo computer simulations, and single nucleosome imaging, we demonstrated the flexible and dynamic nature of the nucleosome fiber in living mammalian cells. We observed local nucleosome fluctuation (~50 nm movement/30 ms) caused by Brownian motion. Our in vivo/in silico results suggest that local nucleosome dynamics facilitate chromatin accessibility and play a critical role in the scanning of genome information.

  14. E-Spun Composite Fibers of Collagen and Dragline Silk Protein: Fiber Mechanics, Biocompatibility, and Application in Stem Cell Differentiation

    PubMed Central

    2015-01-01

    Biocomposite matrices with high mechanical strength, high stability, and the ability to direct matrix-specific stem cell differentiation are essential for the reconstruction of lesioned tissues in tissue engineering and cell therapeutics. Toward this end, we used the electrospinning technique to fabricate well-aligned composite fibers from collagen and spider dragline silk protein, obtained from the milk of transgenic goats, mimicking the native extracellular matrix (ECM) on a similar scale. Collagen and the dragline silk proteins were found to mix homogeneously at all ratios in the electrospun (E-spun) fibers. As a result, the ultimate tensile strength and elasticity of the fibers increased monotonically with silk percentage, whereas the stretchability was slightly reduced. Strikingly, we found that the incorporation of silk proteins to collagen dramatically increased the matrix stability against excessive fiber swelling and shape deformation in cell culture medium. When human decidua parietalis placental stem cells (hdpPSCs) were seeded on the collagen–silk matrices, the matrices were found to support cell proliferation at a similar rate as that of the pure collagen matrix, but they provided cell adhesion with reduced strengths and induced cell polarization at varied levels. Matrices containing 15 and 30 wt % silk in collagen (CS15, CS30) were found to induce a level of neural differentiation comparable to that of pure collagen. In particular, CS15 matrix induced the highest extent of cell polarization and promoted the development of extended 1D neural filaments strictly in-line with the aligned fibers. Taking the increased mechanical strength and fiber stability into consideration, CS15 and CS30 E-spun fibers offer better alternatives to pure collagen fibers as scaffolds that can be potentially utilized in neural tissue repair and the development of future nanobiodevices. PMID:25405355

  15. Cell Attachment to Hydrogel-Electrospun Fiber Mat Composite Materials

    PubMed Central

    Han, Ning; Johnson, Jed K.; Bradley, Patrick A.; Parikh, Kunal S.; Lannutti, John J.; Winter, Jessica O.

    2012-01-01

    Hydrogels, electrospun fiber mats (EFMs), and their composites have been extensively studied for tissue engineering because of their physical and chemical similarity to native biological systems. However, while chemically similar, hydrogels and electrospun fiber mats display very different topographical features. Here, we examine the influence of surface topography and composition of hydrogels, EFMs, and hydrogel-EFM composites on cell behavior. Materials studied were composed of synthetic poly(ethylene glycol) (PEG) and poly(ethylene glycol)-poly(ε-caprolactone) (PEGPCL) hydrogels and electrospun poly(caprolactone) (PCL) and core/shell PCL/PEGPCL constituent materials. The number of adherent cells and cell circularity were most strongly influenced by the fibrous nature of materials (e.g., topography), whereas cell spreading was more strongly influenced by material composition (e.g., chemistry). These results suggest that cell attachment and proliferation to hydrogel-EFM composites can be tuned by varying these properties to provide important insights for the future design of such composite materials. PMID:24955629

  16. Production of cell-free xanthan fermentation broth by cell adsorption on fibers

    PubMed

    Yang; Lo; Chattopadhyay

    1998-03-01

    Xanthan gum is a microbial polysaccharide widely used in food and oil-drilling industries. Xanthan gum produced from the current commercial fermentation process usually contains cells and cell debris, which lower the filterability of the xanthan solution and limit its applications. The production of cell-free xanthan gum fermentation broth is thus desirable. The feasibility of removing cells from the xanthan fermentation broth by cell adsorption to various woven fibrous materials was studied. It was found that both cotton and polyester fibers could be used to adsorb Xanthomonas campestris cells present in the fermentation broth either during batch fermentation or after the fermentation. Almost all cells were removed from the fermentation broth by adsorption to fibers. Cotton terry cloth had rough surfaces and was the preferred material for cell adsorption. Cell adsorption to cotton was faster than to polyester fibers. The adsorption kinetics can be modeled by a first-order rate equation. The adsorption rate constants were 30-40% higher for cotton than for polyester. Cell adsorption was not efficient in the absence of xanthan gum, suggesting that the exopolysaccharide, xanthan gum, was important for efficient cell adsorption to fibers.

  17. The nuclear envelope in the crystalline lens fiber cell.

    PubMed

    Harding, C V; Susan, S R

    1976-05-01

    Rabbit lenses which have been fixed, dehydrated, and dried by a critical-point drying method, can be fractured through the cytoplasm of the differentiating lens fibers, exposing the cell nuclei. The fracture, under these conditions, causes a complete separation of the two membranes of the nuclear envelope from one another, thus exposing entire membrane surfaces (those which line the perinuclear space). These surfaces are not seen in their entirety in typical freeze-fracture or freeze-etch preparations, and consequently have not been described previously. The exposed membrane surfaces which line the perinuclear space have numerous convex structures of approximately 1,000 A, and some larger more irregularly shaped structures. These appear to be fragments of the nuclear pore complexes. Differences in these structures between young fibers and those nearing completion of differentiation is suggested.

  18. Fiber diameters control osteoblastic cell migration and differentiation in electrospun gelatin.

    PubMed

    Sisson, Kristin; Zhang, Chu; Farach-Carson, Mary C; Chase, D Bruce; Rabolt, John F

    2010-09-15

    Defined electrospinning conditions were used to create scaffolds with different fiber diameters to investigate their interactions with osteoblastic MG63 cells. Nonwoven gelatin scaffolds were electrospun with varied fiber diameters to investigate the effect of fiber size and resultant porosity on cell proliferation, viability, migration, and differentiation. The low toxicity solvent acetic acid:ethyl acetate:water ratio and gelatin concentrations were optimized to create small and large diameter fibers. The fiber diameters obtained by this procedure were 110 +/- 40 nm for the small and 600 +/- 110 nm for the large fibers. Cell viability assays showed that MG63 cells grew similarly on both fibers at the early time point (day 3) but preferred the scaffold with large diameter fibers by the later time points (day 5 and day 7). Confocal microscopic imaging showed that MG63 cells migrated poorly (maximum depth of 18 microm) into the scaffold of small diameter fibers, but readily penetrated (maximum depth of 50 microm) into the scaffold of large diameter fibers. Alkaline phosphatase (ALP) assays showed that MG63 cells differentiated on scaffolds made from both diameter fibers. In longer term experiments, MG63 cells differentiated to a greater extent on scaffolds made from small diameter fibers compared to large diameter fibers at days 3 and 7, but the ALP levels were the same for both diameter fibers by day 14. These results indicate that cells can perceive differences in the diameter and resultant pore size of electrospun gelatin fibers and that they process this information to alter their behavior.

  19. The control of cell orientation using biodegradable alginate fibers fabricated by near-field electrospinning.

    PubMed

    Fuh, Yiin-Kuen; Wu, Yun-Chung; He, Zhe-Yu; Huang, Zih-Ming; Hu, Wei-Wen

    2016-05-01

    For spatially controlling cell alignment, near field electrospinning (NFES) was developed to direct-write alginate fiber patterns. Compared to randomly electrospun fibers, NFES fibers guided the extension of HEK 293T cells and the levels of cell alignment increased with decreasing fiber distances. However, these guiding fibers were unfavorable for cell adhesion and limited cell growth. To preserve cell alignment ability and improve biocompatibility, the stability of patterned alginate fibers was adjusted by regulating the level of ion crosslinking. These partially crosslinked NFES fibers demonstrated parallel line-patterns in the initial stage while gradually degraded with time. The reduction of fiber density increased the available area for cell growth and enhanced cell viability. On the other hand, aligned cells were still found on these degraded patterns, suggesting that cell morphologies were mainly guided during cell seeding. This dynamically controlled fiber pattern system fulfilled the need of controlling cell orientation and biocompatibility, thus was potential to modify scaffold surfaces for tissue engineering application.

  20. Liquid crystal cells and optical fibers in neural network implementation

    NASA Astrophysics Data System (ADS)

    Domanski, Andrzej W.; Buczynski, Ryszard; Sierakowski, Marek W.

    1995-08-01

    Optical binary computer may be as easy to operate as parallel system. For such configuration Boolean logic is not very convenient and therefore neural networks should be introduced. In works leading to the paper we used liquid crystal cells as a standard system of liquid crystalline layer between to conducting electrodes in 'sandwich' geometry. We have used 25 micrometers display cells filled with nematic 6CHBT working on 'twisted nematic' effect. Based on such elements a mode of a simple Hopfield network was set up. More advanced experiments were carried out on a model of neurone with supervised learning. The model consists of four laser diodes pigtailed to the multimode optical fibers with 50 micrometers core diameter. The directional couplers help to control the level of input optical power. Four liquid crystal cells allow to change the transmission level according to superivised learning requirements. All the signals were detected by one photodiode. The presented results of experiments are in excellent agreement with theoretical predictions. An additional study was done to check the possibility to build up a linear neural network with Grossberg layer, a neural network with Kohonen layer, and a counter propagation network with two layers of neurones. We have proved that such models may be set up based on simple liquid crystals cells and optical fiber networks.

  1. Hypoxic stellate cells of pancreatic cancer stroma regulate extracellular matrix fiber organization and cancer cell motility.

    PubMed

    Sada, Masafumi; Ohuchida, Kenoki; Horioka, Kohei; Okumura, Takashi; Moriyama, Taiki; Miyasaka, Yoshihiro; Ohtsuka, Takao; Mizumoto, Kazuhiro; Oda, Yoshinao; Nakamura, Masafumi

    2016-03-28

    Desmoplasia and hypoxia in pancreatic cancer mutually affect each other and create a tumor-supportive microenvironment. Here, we show that microenvironment remodeling by hypoxic pancreatic stellate cells (PSCs) promotes cancer cell motility through alteration of extracellular matrix (ECM) fiber architecture. Three-dimensional (3-D) matrices derived from PSCs under hypoxia exhibited highly organized parallel-patterned matrix fibers compared with 3-D matrices derived from PSCs under normoxia, and promoted cancer cell motility by inducing directional migration of cancer cells due to the parallel fiber architecture. Microarray analysis revealed that procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2 (PLOD2) in PSCs was the gene that potentially regulates ECM fiber architecture under hypoxia. Stromal PLOD2 expression in surgical specimens of pancreatic cancer was confirmed by immunohistochemistry. RNA interference-mediated knockdown of PLOD2 in PSCs blocked parallel fiber architecture of 3-D matrices, leading to decreased directional migration of cancer cells within the matrices. In conclusion, these findings indicate that hypoxia-induced PLOD2 expression in PSCs creates a permissive microenvironment for migration of cancer cells through architectural regulation of stromal ECM in pancreatic cancer.

  2. Electrospinning of unidirectionally and orthogonally aligned thermoplastic polyurethane nanofibers: Fiber orientation and cell migration

    PubMed Central

    Mi, Hao-Yang; Salick, Max R.; Jing, Xin; Crone, Wendy C.; Peng, Xiang-Fang; Turng, Lih-Sheng

    2015-01-01

    Unidirectionally and orthogonally aligned thermoplastic polyurethane (TPU) nanofibers were electrospun using a custom-built electrospinning device. The unidirectionally aligned fibers were collected using two parallel copper plates, and the orthogonally aligned fibers were collected using two orthogonal sets of parallel copper plates with alternate negative connections. Carbon nanotubes (CNT) and polyacrylic acid (PAA) were added to modify the polymer solution. It was found that both CNT and PAA were capable of increasing solution conductivity. The TPU/PAA fiber showed the highest degree of fiber orientation with more than 90% of the fibers having an orientation angle between −10° and 10° for unidirectionally aligned fibers, and for orthogonally aligned fibers, the orientation angle of 50% fibers located between −10° and 10° and 48% fibers located between 80° and 100°. Viability assessment of 3T3 fibroblasts cultured on TPU/PAA fibers suggested that the material was cytocompatible. The cells’ orientation and migration direction closely matched the fibers’ orientation. The cell migration velocity and distance were both enhanced with the guidance of fibers compared with cells cultured on random fibers and common tissue culture plastic. Controlling cell migration velocity and directionality may provide ways to influence differentiation and gene expression and systems that would allow further exploration of wound repair and metastatic cell behavior. PMID:24771704

  3. Functional analyses of cotton (Gossypium hirsutum L.) immature fiber (im) mutant reveal that fiber cell wall development is associated with sensitivity to stress.

    USDA-ARS?s Scientific Manuscript database

    Background: Cotton fiber maturity refers the degree of fiber cell wall development and is an important factor for determining commercial value of cotton. The molecular mechanism regulating the fiber cell wall development has not been well characterized. Microscopic image analysis of the cross-sect...

  4. Organization of lipids in fiber-cell plasma membranes of the eye lens.

    PubMed

    Subczynski, Witold K; Mainali, Laxman; Raguz, Marija; O'Brien, William J

    2017-03-01

    The plasma membrane together with the cytoskeleton forms the only supramolecular structure of the matured fiber cell which accounts for mostly all fiber cell lipids. The purpose of this review is to inform researchers about the importance of the lipid bilayer portion of the lens fiber cell plasma membranes in the maintaining lens homeostasis, and thus protecting against cataract development. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. A FIBER APPARATUS IN THE NUCLEUS OF THE YEAST CELL

    PubMed Central

    Robinow, C. F.; Marak, J.

    1966-01-01

    The structure and mode of division of the nucleus of budding yeast cells have been studied by phase-contrast microscopy during life and by ordinary microscopy after Helly fixation. The components of the nucleus were differentially stained by the Feulgen procedure, with Giemsa solution after hydrolysis, and with iron alum haematoxylin. New information was obtained in cells fixed in Helly's by directly staining them with 0.005% acid fuchsin in 1% acetic acid in water. Electron micrographs have been made of sections of cells that were first fixed with 3% glutaraldehyde, then divested of their walls with snail juice, and postfixed with osmium tetroxide. Light and electron microscopy have given concordant information about the organization of the yeast nucleus. A peripheral segment of the nucleus is occupied by relatively dense matter (the "peripheral cluster" of Mundkur) which is Feulgen negative. The greater part of the nucleus is filled with fine-grained Feulgen-positive matter of low density in which chromosomes could not be identified. Chromosomes become visible in this region under the light microscope at meiosis. In the chromatin lies a short fiber with strong affinity for acid fuchsin. The nucleus divides by elongation and constriction, and during this process the fiber becomes long and thin. Electron microscopy has resolved it into a bundle of dark-edged 150 to 180 A filaments which extends between "centriolar plaques" that are attached to the nuclear envelope. PMID:5331666

  6. The influence of fiber diameter of electrospun substrates on neural stem cell differentiation and proliferation.

    PubMed

    Christopherson, Gregory T; Song, Hongjun; Mao, Hai-Quan

    2009-02-01

    Neural stem/progenitor cells (NSCs) are capable of self-renewal and differentiation into all types of neural lineage under different biochemical and topographical cues. In this study, we cultured rat hippocampus-derived adult NSCs (rNSCs) on laminin-coated electrospun Polyethersulfone (PES) fiber meshes with average fiber diameters of 283+/-45 nm, 749+/-153 nm and 1452+/-312 nm; and demonstrated that fiber diameter of PES mesh significantly influences rNSC differentiation and proliferation. Under the differentiation condition (in the presence of 1 microM retinoic acid and 1% fetal bovine serum), rNSCs showed a 40% increase in oligodendrocyte differentiation on 283-nm fibers and 20% increase in neuronal differentiation on 749-nm fibers, in comparison to tissue culture polystyrene surface. SEM imaging revealed that cells stretched multi-directionally to follow underlying 283-nm fibers, but extended along a single fiber axis on larger fibers. When cultured on fiber meshes in serum free medium in the presence of 20 ng/mL of FGF-2, rNSCs showed lower proliferation and more rounded morphology compared to that cultured on laminin-coated 2D surface. As the fiber diameter decreased, higher degree of proliferation and cell spreading and lower degree of cell aggregation were observed. This collective evidence indicates fiber topography can play a vital role in regulating differentiation and proliferation of rNSCs in culture.

  7. Continual Cell Deformation Induced via Attachment to Oriented Fibers Enhances Fibroblast Cell Migration

    PubMed Central

    Qin, Sisi; Ricotta, Vincent; Simon, Marcia; Clark, Richard A. F.; Rafailovich, Miriam H.

    2015-01-01

    Fibroblast migration is critical to the wound healing process. In vivo, migration occurs on fibrillar substrates, and previous observations have shown that a significant time lag exists before the onset of granulation tissue. We therefore conducted a series of experiments to understand the impact of both fibrillar morphology and migration time. Substrate topography was first shown to have a profound influence. Fibroblasts preferentially attach to fibrillar surfaces, and orient their cytoplasm for maximal contact with the fiber edge. In the case of en-mass cell migration out of an agarose droplet, fibroblasts on flat surfaces emerged with an enhanced velocity, v = 52μm/h, that decreases to the single cell value, v = 28μm/h within 24 hours and remained constant for at least four days. Fibroblasts emerging on fibrillar surfaces emerged with the single cell velocity, which remained constant for the first 24 hours and then increased reaching a plateau with more than twice the initial velocity within the next three days. The focal adhesions were distributed uniformly in cells on flat surfaces, while on the fibrillar surface they were clustered along the cell periphery. Furthermore, the number of focal adhesions for the cells on the flat surfaces remained constant, while it decreased on the fibrillar surface during the next three days. The deformation of the cell nuclei was found to be 50% larger on the fiber surfaces for the first 24 hours. While the mean deformation remained constant on the flat surface, it increased for the next three days by 24% in cells on fibers. On the fourth day, large actin/myosin fibers formed in cells on fibrillar surfaces only and coincided with a change from the standard migration mechanism involving extension of lamellipodia, and retraction of the rear, to one involving strong contractions oriented along the fibers and centered about the nucleus. PMID:25774792

  8. Cell-mediated fiber recruitment drives extracellular matrix mechanosensing in engineered fibrillar microenvironments

    PubMed Central

    Baker, Brendon M.; Trappmann, Britta; Wang, William Y.; Sakar, Mahmut S.; Kim, Iris L.; Shenoy, Vivek B.; Burdick, Jason A.; Chen, Christopher S.

    2015-01-01

    To investigate how cells sense stiffness in settings structurally similar to native extracellular matrices (ECM), we designed a synthetic fibrous material with tunable mechanics and user-defined architecture. In contrast to flat hydrogel surfaces, these fibrous materials recapitulated cell-matrix interactions observed with collagen matrices including stellate cell morphologies, cell-mediated realignment of fibers, and bulk contraction of the material. While increasing the stiffness of flat hydrogel surfaces induced mesenchymal stem cell spreading and proliferation, increasing fiber stiffness instead suppressed spreading and proliferation depending on network architecture. Lower fiber stiffness permitted active cellular forces to recruit nearby fibers, dynamically increasing ligand density at the cell surface and promoting the formation of focal adhesions and related signaling. These studies demonstrate a departure from the well-described relationship between material stiffness and spreading established with hydrogel surfaces, and introduce fiber recruitment as a novel mechanism by which cells probe and respond to mechanics in fibrillar matrices. PMID:26461445

  9. Growth changes of 3T3 cells in the presence of mineral fibers

    SciTech Connect

    Dumas, L.; Page, M.

    1986-01-01

    The relationship between exposure to asbestos fibers and the development of mesothelioma or bronchial carcinoma prompted many countries to ban its use from commercial products. The biological mechanism by which asbestos induces or promotes mesothelioma or carcinoma is still unknown. In order to study the influence of fibers on the cell surface, 3T3 fibroblasts were cultured in the presence of various mineral fibers. The acute cytotoxicity produced by mineral fibers was evaluated by the trypan blue dye exclusion method; growth of 3T3 cells was measured as well as the maximum cell density at saturation. It was found that growth of 3T3 cells was slower in the presence of chrysotile while light microscopy revealed an increased cellular chromogenicity and a modification of the cell-cell arrangement in the presence of this fiber. An assay is described in which chrysotile causes an increase in the maximum cell density at saturation.

  10. Cell proliferation on PVA/sodium alginate and PVA/poly(γ-glutamic acid) electrospun fiber.

    PubMed

    Yang, Jen Ming; Yang, Jhe Hao; Tsou, Shu Chun; Ding, Chian Hua; Hsu, Chih Chin; Yang, Kai Chiang; Yang, Chun Chen; Chen, Ko Shao; Chen, Szi Wen; Wang, Jong Shyan

    2016-09-01

    To overcome the obstacles of easy dissolution of PVA nanofibers without crosslinking treatment and the poor electrospinnability of the PVA cross-linked nanofibers via electrospinning process, the PVA based electrospun hydrogel nanofibers are prepared with post-crosslinking method. To expect the electrospun hydrogel fibers might be a promising scaffold for cell culture and tissue engineering applications, the evaluation of cell proliferation on the post-crosslinking electrospun fibers is conducted in this study. At beginning, poly(vinyl alcohol) (PVA), PVA/sodium alginate (PVASA) and PVA/poly(γ-glutamic acid) (PVAPGA) electrospun fibers were prepared by electrospinning method. The electrospun PVA, PVASA and PVAPGA nanofibers were treated with post-cross-linking method with glutaraldehyde (Glu) as crosslinking agent. These electrospun fibers were characterized with thermogravimetry analysis (TGA) and their morphologies were observed with a scanning electron microscope (SEM). To support the evaluation and explanation of cell growth on the fiber, the study of 3T3 mouse fibroblast cell growth on the surface of pure PVA, SA, and PGA thin films is conducted. The proliferation of 3T3 on the electrospun fiber surface of PVA, PVASA, and PVAPGA was evaluated by seeding 3T3 fibroblast cells on these crosslinked electrospun fibers. The cell viability on electrospun fibers was conducted with water-soluble tetrazolium salt-1 assay (Cell Proliferation Reagent WST-1). The morphology of the cells on the fibers was also observed with SEM. The results of WST-1 assay revealed that 3T3 cells cultured on different electrospun fibers had similar viability, and the cell viability increased with time for all electrospun fibers. From the morphology of the cells on electrospun fibers, it is found that 3T3 cells attached on all electrospun fiber after 1day seeded. Cell-cell communication was noticed on day 3 for all electrospun fibers. Extracellular matrix (ECM) productions were found and

  11. Compact and Robust Refilling and Connectorization of Hollow Core Photonic Crystal Fiber Gas Reference Cells

    NASA Technical Reports Server (NTRS)

    Poberezhskiy, Ilya Y.; Meras, Patrick; Chang, Daniel H.; Spiers, Gary D.

    2007-01-01

    This slide presentation reviews a method for refilling and connectorization of hollow core photonic crystal fiber gas reference cells. Thees hollow-core photonic crystal fiber allow optical propagation in air or vacuum and are for use as gas reference cell is proposed and demonstrated. It relies on torch-sealing a quartz filling tube connected to a mechanical splice between regular and hollow-core fibers.

  12. Compact and Robust Refilling and Connectorization of Hollow Core Photonic Crystal Fiber Gas Reference Cells

    NASA Technical Reports Server (NTRS)

    Poberezhskiy, Ilya Y.; Meras, Patrick; Chang, Daniel H.; Spiers, Gary D.

    2007-01-01

    This slide presentation reviews a method for refilling and connectorization of hollow core photonic crystal fiber gas reference cells. Thees hollow-core photonic crystal fiber allow optical propagation in air or vacuum and are for use as gas reference cell is proposed and demonstrated. It relies on torch-sealing a quartz filling tube connected to a mechanical splice between regular and hollow-core fibers.

  13. Smooth muscle-like tissue constructs with circumferentially oriented cells formed by the cell fiber technology.

    PubMed

    Hsiao, Amy Y; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

    2015-01-01

    The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments.

  14. Smooth Muscle-Like Tissue Constructs with Circumferentially Oriented Cells Formed by the Cell Fiber Technology

    PubMed Central

    Hsiao, Amy Y.; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

    2015-01-01

    The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments. PMID:25734774

  15. The Potential to Improve Cell Infiltration in Composite Fiber-Aligned Electrospun Scaffolds by the Selective Removal of Sacrificial Fibers

    PubMed Central

    Baker, Brendon M.; Gee, Albert O.; Metter, Robert B.; Nathan, Ashwin S.; Marklein, Ross L.; Burdick, Jason A.; Mauck, Robert L.

    2008-01-01

    Aligned electrospun scaffolds are a promising tool for engineering fibrous musculoskeletal tissues as they reproduce the mechanical anisotropy of these tissues and can direct ordered neo-tissue formation. However, these scaffolds suffer from a slow cellular infiltration rate, likely due in part to their dense fiber packing. We hypothesized that cell ingress could be expedited in scaffolds by increasing porosity, while at the same time preserving overall scaffold anisotropy. To test this hypothesis, poly(ε-caprolactone) (a slow-degrading polyester) and poly(ethylene oxide) (a water-soluble polymer) were co-electrospun from two separate spinnerets to form dual-polymer composite fiber-aligned scaffolds. Adjusting fabrication parameters produced aligned scaffolds with a full range of sacrificial (PEO) fiber contents. Tensile properties of scaffolds were a function of the ratio of PCL to PEO in the composite scaffolds, and were altered in a predictable fashion with removal of the PEO component. When seeded with mesenchymal stem cells (MSCs), increases in the starting sacrificial fraction (and porosity) improved cell infiltration and distribution after three weeks in culture. In pure PCL scaffolds, cells lined the scaffold periphery, while scaffolds containing >50% sacrificial PEO content had cells present throughout the scaffold. These findings indicate that cell infiltration can be expedited in dense fibrous assemblies with the removal of sacrificial fibers. This strategy may enhance in vitro and in vivo formation and maturation of a functional constructs for fibrous tissue engineering. PMID:18313138

  16. Molecular mechanism of parallel fiber-Purkinje cell synapse formation.

    PubMed

    Mishina, Masayoshi; Uemura, Takeshi; Yasumura, Misato; Yoshida, Tomoyuki

    2012-01-01

    The cerebellum receives two excitatory afferents, the climbing fiber (CF) and the mossy fiber-parallel fiber (PF) pathway, both converging onto Purkinje cells (PCs) that are the sole neurons sending outputs from the cerebellar cortex. Glutamate receptor δ2 (GluRδ2) is expressed selectively in cerebellar PCs and localized exclusively at the PF-PC synapses. We found that a significant number of PC spines lack synaptic contacts with PF terminals and some of residual PF-PC synapses show mismatching between pre- and postsynaptic specializations in conventional and conditional GluRδ2 knockout mice. Studies with mutant mice revealed that in addition to PF-PC synapse formation, GluRδ2 is essential for synaptic plasticity, motor learning, and the restriction of CF territory. GluRδ2 regulates synapse formation through the amino-terminal domain, while the control of synaptic plasticity, motor learning, and CF territory is mediated through the carboxyl-terminal domain. Thus, GluRδ2 is the molecule that bridges synapse formation and motor learning. We found that the trans-synaptic interaction of postsynaptic GluRδ2 and presynaptic neurexins (NRXNs) through cerebellin 1 (Cbln1) mediates PF-PC synapse formation. The synaptogenic triad is composed of one molecule of tetrameric GluRδ2, two molecules of hexameric Cbln1 and four molecules of monomeric NRXN. Thus, GluRδ2 triggers synapse formation by clustering four NRXNs. These findings provide a molecular insight into the mechanism of synapse formation in the brain.

  17. Adenovirus type 2 expresses fiber in monkey-human hybrids and reconstructed cells

    SciTech Connect

    Zorn, G.A.; Anderson, C.W.

    1981-02-01

    Adenovirus type 2 protein expression was measured by indirect immunofluorescence in monkey-human hybrids and in cells reconstructed from monkey and human cell karyoplasts and cytoplasts. Monkey-human hybrid clones infected with adenovirus type 2 expressed fiber protein, whereas infected monkey cells alone did not. Hybrids constructed after the parental monkey cells were infected with adenovirus type 2 demonstrated that fiber synthesis in these cells could be rescued by fusion to uninfected human cells. Thus, human cells contain a dominant factor that acts in trans and overcomes the inability of monkey cells to synthesize fiber. These results are consistent with the hypothesis that the block to adenovirus replication in monkey cells involves a nuclear event that prevents the formation of functional mRNA for some late viral proteins including fiber polypeptide.

  18. PTEN deletion from adult-generated dentate granule cells disrupts granule cell mossy fiber axon structure.

    PubMed

    LaSarge, Candi L; Santos, Victor R; Danzer, Steve C

    2015-03-01

    Dysregulation of the mTOR-signaling pathway is implicated in the development of temporal lobe epilepsy. In mice, deletion of PTEN from hippocampal dentate granule cells leads to mTOR hyperactivation and promotes the rapid onset of spontaneous seizures. The mechanism by which these abnormal cells initiate epileptogenesis, however, is unclear. PTEN-knockout granule cells develop abnormally, exhibiting morphological features indicative of increased excitatory input. If these cells are directly responsible for seizure genesis, it follows that they should also possess increased output. To test this prediction, dentate granule cell axon morphology was quantified in control and PTEN-knockout mice. Unexpectedly, PTEN deletion increased giant mossy fiber bouton spacing along the axon length, suggesting reduced innervation of CA3. Increased width of the mossy fiber axon pathway in stratum lucidum, however, which likely reflects an unusual increase in mossy fiber axon collateralization in this region, offsets the reduction in boutons per axon length. These morphological changes predict a net increase in granule cell innervation of CA3. Increased diameter of axons from PTEN-knockout cells would further enhance granule cell communication with CA3. Altogether, these findings suggest that amplified information flow through the hippocampal circuit contributes to seizure occurrence in the PTEN-knockout mouse model of temporal lobe epilepsy. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. PTEN deletion from adult-generated dentate granule cells disrupts granule cell mossy fiber axon structure

    PubMed Central

    LaSarge, Candi L.; Santos, Victor R; Danzer, Steve C.

    2015-01-01

    Dysregulation of the mTOR-signaling pathway is implicated in the development of temporal lobe epilepsy. In mice, deletion of PTEN from hippocampal dentate granule cells leads to mTOR hyperactivation and promotes the rapid onset of spontaneous seizures. The mechanism by which these abnormal cells initiate epileptogenesis, however, is unclear. PTEN-knockout granule cells develop abnormally, exhibiting morphological features indicative of increased excitatory input. If these cells are directly responsible for seizure genesis, it follows that they should also possess increased output. To test this prediction, dentate granule cell axon morphology was quantified in control and PTEN-knockout mice. Unexpectedly, PTEN deletion increased giant mossy fiber bouton spacing along the axon length, suggesting reduced innervation of CA3. Increased width of the mossy fiber axon pathway in stratum lucidum, however, which likely reflects an unusual increase in mossy fiber axon collateralization in this region, offset the reduction in boutons per axon length. These morphological changes predicts a net increase in granule cell >> CA3 innervation. Increased diameter of axons from PTEN-knockout cells would further enhance granule cell >> CA3 communication. Altogether, these findings suggest that amplified information flow through the hippocampal circuit contributes to seizure occurrence in the PTEN-knockout mouse model of temporal lobe epilepsy. PMID:25600212

  20. Selective targeting of human cells by a chimeric adenovirus vector containing a modified fiber protein.

    PubMed Central

    Stevenson, S C; Rollence, M; Marshall-Neff, J; McClelland, A

    1997-01-01

    The adenovirus fiber protein is responsible for attachment of the virion to unidentified cell surface receptors. There are at least two distinct adenovirus fiber receptors which interact with the group B (Ad3) and group C (Ad5) adenoviruses. We have previously shown by using expressed adenovirus fiber proteins that it is possible to change the specificity of the fiber protein by exchanging the head domain with another serotype which recognizes a different receptor (S. C. Stevenson et al., J. Virol. 69:2850-2857, 1995). A chimeric fiber cDNA containing the Ad3 fiber head domain fused to the Ad5 fiber tail and shaft was incorporated into the genome of an adenovirus vector with E1 and E3 deleted encoding beta-galactosidase to generate Av9LacZ4, an adenovirus particle which contains a chimeric fiber protein. Western blot analysis of the chimeric fiber vector confirmed expression of the chimeric fiber protein and its association with the adenovirus capsid. Transduction experiments with fiber protein competitors demonstrated the altered receptor tropism of the chimeric fiber vector compared to that of the parental Av1LacZ4 vector. Transduction of a panel of human cell lines with the chimeric and parental vectors provided evidence for a different cellular distribution of the Ad5 and Ad3 receptors. Three cell lines (THP-1, MRC-5, and FaDu) were more efficiently transduced by the vector containing the Ad3 fiber head than by the Ad5 fiber vector. In contrast, human coronary artery endothelial cells were transduced more readily with the vector containing the Ad5 fiber than with the chimeric fiber vector. HeLa and human umbilical vein endothelial cells were transduced at equivalent levels compared with human diploid fibroblasts, which were refractory to transduction with both vectors. These results provide evidence for the differential expression of the Ad5 and Ad3 receptors on human cell lines derived from clinically relevant target tissues. Furthermore, we show that exchange

  1. Dissecting Regional Variations in Stress Fiber Mechanics in Living Cells with Laser Nanosurgery

    SciTech Connect

    Tanner, Kandice; Boudreau, Aaron; Bissell, Mina J; Kumar, Sanjay

    2010-03-02

    The ability of a cell to distribute contractile stresses across the extracellular matrix in a spatially heterogeneous fashion underlies many cellular behaviors, including motility and tissue assembly. Here we investigate the biophysical basis of this phenomenon by using femtosecond laser nanosurgery to measure the viscoelastic recoil and cell-shape contributions of contractile stress fibers (SFs) located in specific compartments of living cells. Upon photodisruption and recoil, myosin light chain kinase-dependent SFs located along the cell periphery display much lower effective elasticities and higher plateau retraction distances than Rho-associated kinase-dependent SFs located in the cell center, with severing of peripheral fibers uniquely triggering a dramatic contraction of the entire cell within minutes of fiber irradiation. Image correlation spectroscopy reveals that when one population of SFs is pharmacologically dissipated, actin density flows toward the other population. Furthermore, dissipation of peripheral fibers reduces the elasticity and increases the plateau retraction distance of central fibers, and severing central fibers under these conditions triggers cellular contraction. Together, these findings show that SFs regulated by different myosin activators exhibit different mechanical properties and cell shape contributions. They also suggest that some fibers can absorb components and assume mechanical roles of other fibers to stabilize cell shape.

  2. High temperature battery cell comprising stress-free hollow fiber bundle

    SciTech Connect

    Anand, J.N.; Revak, T.T.; Rossini, F.J.

    1982-06-01

    Thermal stressing of hollow fibers constituting the electrolyteseparator in a high temperature battery cell, and of certain other elements thereof, is avoided by suspending the assembly comprising the anolyte tank, the tubesheet, the hollow fibers and a cathodic current collector-distributing means, within the casing and employing a limp connection between the latter means and the cathode terminal of the cell.

  3. Curvature and Rho activation differentially control the alignment of cells and stress fibers

    PubMed Central

    Bade, Nathan D.; Kamien, Randall D.; Assoian, Richard K.; Stebe, Kathleen J.

    2017-01-01

    In vivo, cells respond to a host of physical cues ranging from substrate stiffness to the organization of micro- and nanoscale fibrous networks. We show that macroscale substrates with radii of curvature from tens to hundreds of micrometers influence cell alignment. In a model system of fibroblasts, isolated cells aligned strongly in the axial direction on cylinders with radii similar to the cell length and more weakly on cylinders of much larger radius. Isolated vascular smooth muscle cells did not align as effectively as fibroblasts. However, both cell types aligned robustly in weak curvature fields when in confluent monolayers. We identified two distinct populations of stress fibers in both cell types: long, apical stress fibers that aligned axially and short, basal stress fibers that aligned circumferentially. Circumferential alignment of the basal stress fibers is in apparent disagreement with a long-standing hypothesis that energetic penalties for bending enforce axial alignment on cylinders. To explore this phenomenon, we manipulated stress fibers by activating Rho, a small guanosine triphosphatase that regulates stress fiber assembly. In response, apical stress fibers disassembled, whereas basal stress fibers thickened and aligned more strongly in the circumferential direction. By activating Rho in confluent monolayers of vascular smooth muscle cells, we recapitulated the circumferential alignment pattern of F-actin within these cells that is observed in cylindrical vessels in vivo. In agreement with recent theory, these results suggest that stress fiber bending penalties are overcome when stress fiber contractility is enhanced and motivate deeper study of the mechanics of these distinct stress fiber populations. PMID:28913421

  4. Curvature and Rho activation differentially control the alignment of cells and stress fibers.

    PubMed

    Bade, Nathan D; Kamien, Randall D; Assoian, Richard K; Stebe, Kathleen J

    2017-09-01

    In vivo, cells respond to a host of physical cues ranging from substrate stiffness to the organization of micro- and nanoscale fibrous networks. We show that macroscale substrates with radii of curvature from tens to hundreds of micrometers influence cell alignment. In a model system of fibroblasts, isolated cells aligned strongly in the axial direction on cylinders with radii similar to the cell length and more weakly on cylinders of much larger radius. Isolated vascular smooth muscle cells did not align as effectively as fibroblasts. However, both cell types aligned robustly in weak curvature fields when in confluent monolayers. We identified two distinct populations of stress fibers in both cell types: long, apical stress fibers that aligned axially and short, basal stress fibers that aligned circumferentially. Circumferential alignment of the basal stress fibers is in apparent disagreement with a long-standing hypothesis that energetic penalties for bending enforce axial alignment on cylinders. To explore this phenomenon, we manipulated stress fibers by activating Rho, a small guanosine triphosphatase that regulates stress fiber assembly. In response, apical stress fibers disassembled, whereas basal stress fibers thickened and aligned more strongly in the circumferential direction. By activating Rho in confluent monolayers of vascular smooth muscle cells, we recapitulated the circumferential alignment pattern of F-actin within these cells that is observed in cylindrical vessels in vivo. In agreement with recent theory, these results suggest that stress fiber bending penalties are overcome when stress fiber contractility is enhanced and motivate deeper study of the mechanics of these distinct stress fiber populations.

  5. In vivo cultivation of tumor cells in hollow fibers.

    PubMed

    Hollingshead, M G; Alley, M C; Camalier, R F; Abbott, B J; Mayo, J G; Malspeis, L; Grever, M R

    1995-01-01

    Advancement of potential anti-cancer agents from "discovery" in an in vitro screen to pre-clinical development requires a demonstration of in vivo efficacy in one or more animal models of neoplastic disease. Most such models require considerable materials in terms of laboratory animals and test compound as well as substantial amounts of time (and cost) to determine whether a given experimental agent or series of agents have even minimal anti-tumor activity. The present study was initiated to assess the feasibility of employing an alternate methodology for preliminary in vivo evaluations of therapeutic efficacy. Results of experimentation to date demonstrate that a hollow fiber encapsulation/implantation methodology provides quantitative indices of drug efficacy with minimum expenditures of time and materials. Following further pharmacologic calibrations, the hollow fiber technique is anticipated (a) to identify compounds having moderate to prominent anti-cancer activity and (b) to facilitate the identification of sensitive tumor cell line "targets" and optimal or near-optimal treatment regimens for subsequent testing using standard in vivo solid tumor models. The potential suitability of this methodology is demonstrated with several standard anti-neoplastic agents.

  6. Adenovirus Vector Pseudotyping in Fiber-Expressing Cell Lines: Improved Transduction of Epstein-Barr Virus-Transformed B Cells

    PubMed Central

    Von Seggern, Dan J.; Huang, Shuang; Fleck, Shonna Kaye; Stevenson, Susan C.; Nemerow, Glen R.

    2000-01-01

    While adenovirus (Ad) gene delivery vectors are useful in many gene therapy applications, their broad tropism means that they cannot be directed to a specific target cell. There are also a number of cell types involved in human disease which are not transducible with standard Ad vectors, such as Epstein-Barr virus (EBV)-transformed B lymphocytes. Adenovirus binds to host cells via the viral fiber protein, and Ad vectors have previously been retargeted by modifying the fiber gene on the viral chromosome. This requires that the modified fiber be able to bind to the cell in which the vector is grown, which prevents truly specific vector targeting. We previously reported a gene delivery system based on a fiber gene-deleted Ad type 5 (Ad5) vector (Ad5.βgal.ΔF) and packaging cells that express the viral fiber protein. Expression of different fibers in packaging cells will allow Ad retargeting without modifying the viral chromosome. Importantly, fiber proteins which can no longer bind to the producer cells can also be used. Using this approach, we generated for the first time pseudotyped Ad5.βgal.ΔF particles containing either the wild-type Ad5 fiber protein or a chimeric fiber with the receptor-binding knob domain of the Ad3 fiber. Particles equipped with the chimeric fiber bound to the Ad3 receptor rather than the coxsackievirus-adenovirus receptor protein used by Ad5. EBV-transformed B lymphocytes were infected efficiently by the Ad3-pseudotyped particles but poorly by virus containing the Ad5 fiber protein. The strategy described here represents a broadly applicable method for targeting gene delivery to specific cell types. PMID:10590124

  7. Observation of Chinese Hamster Ovary Cells retained inside the non-woven fiber matrix of the CellTank bioreactor.

    PubMed

    Zhang, Ye; Chotteau, Véronique

    2015-12-01

    This data article shows how the recombinant Chinese Hamster Ovary (CHO) cells are located in the interstices of the matrix fibers of a CellTank bioreactor after completion of a perfusion culture, supporting the article entitled "Very high cell density perfusion of CHO cells anchored in a non-woven matrix-based bioreactor" by Zhang et al. [1]. It provides a visualization of the cell distribution in the non-woven fiber matrix in a deeper view.

  8. Observation of Chinese Hamster Ovary Cells retained inside the non-woven fiber matrix of the CellTank bioreactor

    PubMed Central

    Zhang, Ye; Chotteau, Véronique

    2015-01-01

    This data article shows how the recombinant Chinese Hamster Ovary (CHO) cells are located in the interstices of the matrix fibers of a CellTank bioreactor after completion of a perfusion culture, supporting the article entitled “Very high cell density perfusion of CHO cells anchored in a non-woven matrix-based bioreactor” by Zhang et al. [1]. It provides a visualization of the cell distribution in the non-woven fiber matrix in a deeper view. PMID:26958613

  9. Sliding Fibers: Slidable, Injectable, and Gel-like Electrospun Nanofibers as Versatile Cell Carriers.

    PubMed

    Lee, Slgirim; Yun, Seokhwan; Park, Kook In; Jang, Jae-Hyung

    2016-03-22

    Designing biomaterial systems that can mimic fibrous, natural extracellular matrix is crucial for enhancing the efficacy of various therapeutic tools. Herein, a smart technology of three-dimensional electrospun fibers that can be injected in a minimally invasive manner was developed. Open surgery is currently the only route of administration of conventional electrospun fibers into the body. Coordinating electrospun fibers with a lubricating hydrogel produced fibrous constructs referred to as slidable, injectable, and gel-like (SLIDING) fibers. These SLIDING fibers could pass smoothly through a catheter and fill any cavity while maintaining their fibrous morphology. Their injectable features were derived from their distinctive rheological characteristics, which were presumably caused by the combinatorial effects of mobile electrospun fibers and lubricating hydrogels. The resulting injectable fibers fostered a highly favorable environment for human neural stem cell (hNSC) proliferation and neurosphere formation within the fibrous structures without compromising hNSC viability. SLIDING fibers demonstrated superior performance as cell carriers in animal stroke models subjected to the middle cerebral artery occlusion (MCAO) stroke model. In this model, SLIDING fiber application extended the survival rate of administered hNSCs by blocking microglial infiltration at the early, acute inflammatory stage. The development of SLIDING fibers will increase the clinical significance of fiber-based scaffolds in many biomedical fields and will broaden their applicability.

  10. Receptor mobility and the binding of cells to lectin-coated fibers

    PubMed Central

    1975-01-01

    The ability of cells to bind to nylon fibers coated with lectin molecules interspaced with varying numbers of albumin molecules has been analyzed. The cells used were lymphoma cells, normal lymphocytes, myeloid leukemia cells, and normal and transformed fibroblasts, and the fibers were coated with different densities of concanavalin A or the lectins from soybean or wheat germ. Cells fixed with glutaraldehyde did not bind to lectin-coated fibers. The number of cells bound to fibers could be increased by increasing the density of lectin molecules on the fiber, the density of specific receptors on the cell, or the mobility of the receptors. It is suggested that binding of cells to fibers involves alignment and binding of specific cell surface receptors with lectin molecules immobilized on the fibers, and that this alignment requires short-range rapid lateral mobility (RLM) of the receptors. The titration of cell binding to fibers coated with different densities of lectin and albumin has been used to measure the relative RLM of unoccupied cell surface receptors for the lectin. The results indicate a relationship of RLM to lectin-induced cell-to-cell binding. The RLM or receptors for concanavalin A (Con A) was generally found to be higher than that of receptors for the lectins from wheat germ or soybean. Receptor RLM could be decreased by use of metabolic inhibitors or by lowering the temperature. Receptors for Con A had a lower RLM on normal fibroblasts than on SV40-transformed fibroblasts, and trypsinization of normal fibroblasts increased Con A receptor RLM. Normal lymphocytes, lymphoma cells, and lines of myeloid leukemia cells that can be induced to differentiate had a high receptor RLM, whereas lines of myeloid leukemia cells that could not be induced to differentiate had a low receptor RLM. These results suggest that the RLM of Con A receptors is related to the transformation of fibroblasts and the ability of myeloid leukemia cells to undergo differentiation PMID

  11. Adenovirus type 2 expresses fiber in monkey-human hybrids and reconstructed cells.

    PubMed Central

    Zorn, G A; Anderson, C W

    1981-01-01

    Adenovirus type 2 protein expression was measured by indirect immunofluorescence in monkey-human hybrids and in cells reconstructed from monkey and human cell karyoplasts and cytoplasts. Monkey-human hybrid clones infected with adenovirus type 2 expressed fiber protein, whereas infected monkey cells alone did not. Hybrids constructed after the parental monkey cells were infected with adenovirus type 2 demonstrated that fiber synthesis in these cells could be rescued by fusion to uninfected human cells. Thus, human cells contain a dominant factor that acts in trans and overcomes the inability of monkey cells to synthesize fiber. Cells reconstructed from infected human karyoplasts and monkey cytoplasts expressed fiber, whereas cells reconstructed from infected monkey karyoplasts and human cytoplasts did not. These results are consistent with the hypothesis that the block to adenovirus replication in monkey cells involves a nuclear event that prevents the formation of functional mRNA for some late viral proteins including fiber polypeptide. Furthermore, they suggest that the translational apparatus of monkey cells is competent to translate functional fiber mRNA synthesized in human cells. Images PMID:7218436

  12. Engineering cholesterol-based fibers for antibody immobilization and cell capture

    NASA Astrophysics Data System (ADS)

    Cohn, Celine

    In 2015, the United States is expected to have nearly 600,000 deaths attributed to cancer. Of these 600,000 deaths, 90% will be a direct result of cancer metastasis, the spread of cancer throughout the body. During cancer metastasis, circulating tumor cells (CTCs) are shed from primary tumors and migrate through bodily fluids, establishing secondary cancer sites. As cancer metastasis is incredibly lethal, there is a growing emphasis on developing "liquid biopsies" that can screen peripheral blood, search for and identify CTCs. One popular method for capturing CTCs is the use of a detection platform with antibodies specifically suited to recognize and capture cancer cells. These antibodies are immobilized onto the platform and can then bind and capture cells of interest. However, current means to immobilize antibodies often leave them with drastically reduced function. The antibodies are left poorly suited for cell capture, resulting in low cell capture efficiencies. This body of work investigates the use of lipid-based fibers to immobilize proteins in a way that retains protein function, ultimately leading to increased cell capture efficiencies. The resulting increased efficiencies are thought to arise from the retained three-dimensional structure of the protein as well as having a complete coating of the material surface with antibodies that are capable of interacting with their antigens. It is possible to electrospin cholesterol-based fibers that are similar in design to the natural cell membrane, providing proteins a more natural setting during immobilization. Such fibers have been produced from cholesterol-based cholesteryl succinyl silane (CSS). These fibers have previously illustrated a keen aptitude for retaining protein function and increasing cell capture. Herein the work focuses on three key concepts. First, a model is developed to understand the immobilization mechanism used by electrospun CSS fibers. The antibody immobilization and cell capturing

  13. High performance methanol-oxygen fuel cell with hollow fiber electrode

    NASA Technical Reports Server (NTRS)

    Lawson, Daniel D. (Inventor); Ingham, John D. (Inventor)

    1983-01-01

    A methanol/air-oxygen fuel cell including an electrode formed by open-ended ion-exchange hollow fibers having a layer of catalyst deposited on the inner surface thereof and a first current collector in contact with the catalyst layer. A second current collector external of said fibers is provided which is immersed along with the hollow fiber electrode in an aqueous electrolyte body. Upon passage of air or oxygen through the hollow fiber electrode and introduction of methanol into the aqueous electrolyte, a steady current output is obtained. Two embodiments of the fuel cell are disclosed. In the first embodiment the second metal electrode is displaced away from the hollow fiber in the electrolyte body while in the second embodiment a spiral-wrap electrode is provided about the outer surface of the hollow fiber electrode.

  14. Cotton fiber cell walls of Gossypium hirsutum and Gossypium barbadense have differences related to loosely-bound xyloglucan.

    PubMed

    Avci, Utku; Pattathil, Sivakumar; Singh, Bir; Brown, Virginia L; Hahn, Michael G; Haigler, Candace H

    2013-01-01

    Cotton fiber is an important natural textile fiber due to its exceptional length and thickness. These properties arise largely through primary and secondary cell wall synthesis. The cotton fiber of commerce is a cellulosic secondary wall surrounded by a thin cuticulated primary wall, but there were only sparse details available about the polysaccharides in the fiber cell wall of any cotton species. In addition, Gossypium hirsutum (Gh) fiber was known to have an adhesive cotton fiber middle lamella (CFML) that joins adjacent fibers into tissue-like bundles, but it was unknown whether a CFML existed in other commercially important cotton fibers. We compared the cell wall chemistry over the time course of fiber development in Gh and Gossypium barbadense (Gb), the two most important commercial cotton species, when plants were grown in parallel in a highly controlled greenhouse. Under these growing conditions, the rate of early fiber elongation and the time of onset of secondary wall deposition were similar in fibers of the two species, but as expected the Gb fiber had a prolonged elongation period and developed higher quality compared to Gh fiber. The Gb fibers had a CFML, but it was not directly required for fiber elongation because Gb fiber continued to elongate rapidly after CFML hydrolysis. For both species, fiber at seven ages was extracted with four increasingly strong solvents, followed by analysis of cell wall matrix polysaccharide epitopes using antibody-based Glycome Profiling. Together with immunohistochemistry of fiber cross-sections, the data show that the CFML of Gb fiber contained lower levels of xyloglucan compared to Gh fiber. Xyloglucan endo-hydrolase activity was also higher in Gb fiber. In general, the data provide a rich picture of the similarities and differences in the cell wall structure of the two most important commercial cotton species.

  15. Connexin 50 Regulates Surface Ball-and-Socket Structures and Fiber Cell Organization

    PubMed Central

    Wang, Eddie; Geng, Andrew; Maniar, Ankur M.; Mui, Byron W. H.; Gong, Xiaohua

    2016-01-01

    Purpose The roles of gap junction protein connexin 50 (Cx50) encoded by Gja8, during lens development are not fully understood. Connexin 50 knockout (KO) lenses have decreased proliferation of epithelial cells and altered fiber cell denucleation. We further investigated the mechanism for cellular defects in Cx50 KO (Gja8−/−) lenses. Methods Fiber cell morphology and subcellular distribution of various lens membrane/cytoskeleton proteins from wild-type and Cx50 KO mice were visualized by immunofluorescent staining and confocal microscopy. Results We observed multiple morphological defects in the cortical fibers of Cx50 KO lenses, including abnormal fiber cell packing geometry, decreased F-actin enrichment at tricellular vertices, and disrupted ball-and-socket (BS) structures on the long sides of hexagonal fibers. Moreover, only small gap junction plaques consisting of Cx46 (α3 connexin) were detected in cortical fibers and the distributions of the BS-associated beta-dystroglycan and ZO-1 proteins were altered. Conclusions Connexin 50 gap junctions are important for BS structure maturation and cortical fiber cell organization. Connexin 50–based gap junction plaques likely form structural domains with an array of membrane/cytoskeletal proteins to stabilize BS. Loss of Cx50-mediated coupling, BS disruption, and altered F-actin in Cx50 KO fibers, thereby contribute to the small lens and mild cataract phenotypes. PMID:27281269

  16. Climbing fiber synapse elimination in cerebellar Purkinje cells.

    PubMed

    Watanabe, Masahiko; Kano, Masanobu

    2011-11-01

    Innervation of Purkinje cells (PCs) by multiple climbing fibers (CFs) is refined into mono-innervation during the first three postnatal weeks of rodents' lives. In this review article, we will integrate the current knowledge on developmental process and mechanisms of CF synapse elimination. In the 'creeper' stage of CF innervation (postnatal day 0 (P0)∼), CFs creep among PC somata to form transient synapses on immature dendrites. In the 'pericellular nest' stage (P5∼), CFs densely surround and innervate PC somata. CF innervation is then displaced to the apical portion of PC somata in the 'capuchon' stage (P9∼), and translocate to dendrites in the 'dendritic' (P12∼) stage. Along with the developmental changes in CF wiring, functional and morphological distinctions become larger among CF inputs. PCs are initially innervated by more than five CFs with similar strengths (∼P3). During P3-7 only a single CF is selectively strengthened (functional differentiation), and it undergoes dendritic translocation from P9 on (dendritic translocation). Following the functional differentiation, perisomatic CF synapses are eliminated nonselectively; this proceeds in two distinct phases. The early phase (P7-11) is conducted independently of parallel fiber (PF)-PC synapse formation, while the late phase (P12-17) critically depends on it. The P/Q-type voltage-dependent Ca(2+) channel in PCs triggers selective strengthening of single CF inputs, promotes dendritic translocation of the strengthened CFs, and drives the early phase of CF synapse elimination. In contrast, the late phase is mediated by the mGluR1-Gαq-PLCβ4-PKCγ signaling cascade in PCs driven at PF-PC synapses, whose structural connectivity is stabilized and maintained by the GluRδ2-Cbln1-neurexin system.

  17. Climbing Fiber Regulation of Spontaneous Purkinje Cell Activity and Cerebellum-Dependent Blink Responses123

    PubMed Central

    Bengtsson, Fredrik

    2016-01-01

    Abstract It has been known for a long time that GABAergic Purkinje cells in the cerebellar cortex, as well as their target neurons in the cerebellar nuclei, are spontaneously active. The cerebellar output will, therefore, depend on how input is integrated into this spontaneous activity. It has been shown that input from climbing fibers originating in the inferior olive controls the spontaneous activity in Purkinje cells. While blocking climbing fiber input to the Purkinje cells causes a dramatic increase in the firing rate, increased climbing fiber activity results in reduced Purkinje cell activity. However, the exact calibration of this regulation has not been examined systematically. Here we examine the relation between climbing fiber stimulation frequency and Purkinje cell activity in unanesthetized decerebrated ferrets. The results revealed a gradual suppression of Purkinje cell activity, starting at climbing fiber stimulation frequencies as low as 0.5 Hz. At 4 Hz, Purkinje cells were completely silenced. This effect lasted an average of 2 min after the stimulation rate was reduced to a lower level. We also examined the effect of sustained climbing fiber stimulation on overt behavior. Specifically, we analyzed conditioned blink responses, which are known to be dependent on the cerebellum, while stimulating the climbing fibers at different frequencies. In accordance with the neurophysiological data, the conditioned blink responses were suppressed at stimulation frequencies of ≥4 Hz. PMID:26839917

  18. Quantitative analysis of granule cell axons and climbing fiber afferents in the turtle cerebellar cortex.

    PubMed

    Tolbert, D L; Conoyer, B; Ariel, M

    2004-11-01

    The turtle cerebellar cortex is a single flat sheet of gray matter that greatly facilitates quantitative analysis of biotylinated dextran amine labeled granule cell and olivocerebellar axons and Nissl-stained granule and Purkinje neurons. On average, ascending granule cell axons are relatively thicker than their parallel fiber branches (mean +/- SD: 0.84 +/- 0.17 vs 0.64 +/- 0.12 microm, respectively). Numerous en passant swellings, the site of presynaptic contact, were present on both ascending and parallel fiber granule cell axons. The swellings on ascending axons (1.82 +/- 0.34 microm, n = 52) were slightly larger than on parallel fibers (1.43 +/- 0.24 microm, n = 430). In addition, per unit length (100 microm) there were more swellings on ascending axons (11.2 +/- 4.2) than on parallel fibers (9.7 +/- 4.2). Each parallel fiber branch from an ascending axon is approximately 1.5 mm long. Olivocerebellar climbing fiber axons followed the highly tortuous dendrites of Purkinje cells in the inner most 15-20% of the molecular layer. Climbing fibers displayed relatively fewer en passant swellings. The spatial perimeter of climbing fiber arbors (area) increased 72% from anteriorly (1797 microm2) to posteriorly (3090 microm2) and 104% from medially (1690 microm2) to laterally (3450 microm2). Differences in the size and spacing of en passant swellings on granule cell axons suggest that ascending axons may have a functionally more significant impact on the excitability of a limited number of radially overlying Purkinje cells than the single contacts by parallel fiber with multiple orthogonally aligned Purkinje cell dendrites. The spatially restricted distribution of climbing fibers to the inner most molecular layer, the paucity of en passant swellings, and different terminal arbor areas are enigmatic. Nevertheless, these finding provide important anatomical information for future optical imaging and electrophysiological experiments.

  19. Light Weight Design Nickel-Alkaline Cells Using Fiber Electrodes

    NASA Technical Reports Server (NTRS)

    Pickett, David F.; Willis, Bob; Britton, Doris; Saelens, Johan

    2005-01-01

    Using fiber electrode technology, currently produced by Bekaert Corporation (Bekaert), Electro Energy, Inc., (EEI) Mobile Energy Products Group (formerly, Eagle-Picher Technologies, LLC., Power Systems Department) in Colorado Springs, CO has demonstrated that it is feasible to manufacture flight weight nickel-hydrogen cells having about twice the specific energy (80 vs. 40 watt-hr/kg) as state-of-the-art nickel-hydrogen cells that are flown on geosynchronous communications satellites. Although lithium-ion battery technology has made large in-roads to replace the nickel-alkaline technology (nickel-cadmium, nickel-metal hydride), the technology offered here competes with lithium-ion weight and offers alternatives not present in the lithium-ion chemistry such as ability to undergo continuous overcharge, reversal on discharge and sustain rate capability sufficient to start automotive and aircraft engines at subzero temperatures. In development to date seven 50 ampere-hour nickel-hydrogen have been constructed, acceptance tested and briefly tested in a low earth orbit (LEO) cycle regime. The effort was jointly funded by Electro Energy, Inc. and NASA Glenn Research Center, Cleveland, OH. Five of the seven cells have been shipped to NASA GRC for further cycle testing. Two of the cells experienced failure due to internal short circuits during initial cycle testing at EEL Destructive Physical Analysis (DPA) of one of the cells has shown the failure mode to be due to inadequate hydrogen catalyst electrodes that were not capacity balanced with the higher energy density nickel oxide electrodes. In the investigators opinion, rebuild of the cells using proper electrode balance would result in cells that could sustain over 30,000 cycles at moderate depths-of-discharge in a LEO regime or endure over 20 years of geosynchronous orbit (GEO) cycling while realizing a two-fold increase in specific energy for the battery or a 1.1 kg weight savings per 50 ampere-hour cell. Additional

  20. Light Weight Design Nickel-Alkaline Cells Using Fiber Electrodes

    NASA Technical Reports Server (NTRS)

    Pickett, David F.; Willis, Bob; Britton, Doris; Saelens, Johan

    2005-01-01

    Using fiber electrode technology, currently produced by Bekaert Corporation (Bekaert), Electro Energy, Inc., (EEI) Mobile Energy Products Group (formerly, Eagle-Picher Technologies, LLC., Power Systems Department) in Colorado Springs, CO has demonstrated that it is feasible to manufacture flight weight nickel-hydrogen cells having about twice the specific energy (80 vs. 40 watt-hr/kg) as state-of-the-art nickel-hydrogen cells that are flown on geosynchronous communications satellites. Although lithium-ion battery technology has made large in-roads to replace the nickel-alkaline technology (nickel-cadmium, nickel-metal hydride), the technology offered here competes with lithium-ion weight and offers alternatives not present in the lithium-ion chemistry such as ability to undergo continuous overcharge, reversal on discharge and sustain rate capability sufficient to start automotive and aircraft engines at subzero temperatures. In development to date seven 50 ampere-hour nickel-hydrogen have been constructed, acceptance tested and briefly tested in a low earth orbit (LEO) cycle regime. The effort was jointly funded by Electro Energy, Inc. and NASA Glenn Research Center, Cleveland, OH. Five of the seven cells have been shipped to NASA GRC for further cycle testing. Two of the cells experienced failure due to internal short circuits during initial cycle testing at EEL Destructive Physical Analysis (DPA) of one of the cells has shown the failure mode to be due to inadequate hydrogen catalyst electrodes that were not capacity balanced with the higher energy density nickel oxide electrodes. In the investigators opinion, rebuild of the cells using proper electrode balance would result in cells that could sustain over 30,000 cycles at moderate depths-of-discharge in a LEO regime or endure over 20 years of geosynchronous orbit (GEO) cycling while realizing a two-fold increase in specific energy for the battery or a 1.1 kg weight savings per 50 ampere-hour cell. Additional

  1. Effectiveness of two synthetic fiber filters for removing white cells from AS-1 red cells.

    PubMed

    Pikul, F J; Farrar, R P; Boris, M B; Estok, L; Marlo, D; Wildgen, M; Chaplin, H

    1989-09-01

    Two commercially available synthetic fiber filters were studied for their effectiveness at removing white cells (WBCs) from AS-1-preserved red cells (RBCs) stored less than or equal to 14 days. In all, 65 filtrations were performed. An automated microprocessor-controlled hydraulic system designed for use with cellulose acetate fiber filters was employed to prepare filtered RBCs before release for transfusion. Studies were also carried out on polyester fiber filters, which are designed to be used in-line during transfusion. Residual WBCs were below the accurate counting range of Coulter counters and of conventional manual chamber counts. An isosmotic ammonium chloride RBC lysis method, plus a modified chamber counting technique, permitted a 270-fold increase over the number of WBCs counted by the conventional manual method. For the polyester fiber-filtered products, residual WBCs per unit were not affected by speed of filtration, prior length of storage, or mechanical tapping during filtration. The effectiveness of WBC removal (mean 99.7%), total residual WBCs (means, 4.8 and 5.5 x 10(6], and RBC recovery (mean, 93%) was the same for both filters. The majority of residual WBCs were lymphocytes. WBC removal and RBC recovery were strikingly superior to results reported with nonfiltration methods.

  2. Effects of asbestos fibers on cell division, cell survival, and formation of thioguanine-resistant mutants in Chinese hamster ovary cells

    SciTech Connect

    Kenne, K.; Ljungquist, S.; Ringertz, N.R.

    1986-04-01

    The ability of crocidolite fibers to induce point mutations and mitotic abnormalities in Chinese hamster ovary (CHO) cells was examined in cell cultures. The purpose has been to study the possibilities for establishing in vitro test methods to quantify genetic damage induced by asbestos and other mineral fibers. Results obtained with the CHO/hypoxanthine guanine phosphoribosyl transferase system indicated that crocidolite fibers per se do not significantly increase the number of thioguanine-resistant mutants. Crocidolite fibers also failed to potentiate the mutagenicity of benzo(a)pyrene. Time-lapse cinematography and microscopy showed that asbestos (crocidolite) fibers were markedly cytotoxic. Among surviving cells some underwent abnormal cell divisions which resulted in multi- and micronucleate cells. Many cells that contained a few asbestos fibers, however, underwent mitosis and successfully formed two mononucleate daughter cells capable of further divisions. Individual, fiber-containing cells were examined by time-lapse television recordings for 4-5 days. During this time period some cells underwent six divisions and generated an almost normal number of daughter cells. Cells which contained fibers that were longer or equivalent to the diameter of the mitotic cell (20 ..mu..m), showed different forms of mitotic abnormalities. The frequency of multinucleate cells was drastically increased following exposure to asbestos fibers. Only rarely, however, did these cells divide to produce viable daughter cells capable of continued cell multiplication. The frequency of multinucleate cells was dependent on the dose of exposure to asbestos fibers and could possible be used as an index of the degree of mitotic disturbances induced by mineral fibers.

  3. Comparative transcriptome analysis of epithelial and fiber cells in newborn mouse lenses with RNA sequencing

    PubMed Central

    Hoang, Thanh V.; Kumar, Praveen Kumar Raj; Sutharzan, Sreeskandarajan; Tsonis, Panagiotis A.; Liang, Chun

    2014-01-01

    Purpose The ocular lens contains only two cell types: epithelial cells and fiber cells. The epithelial cells lining the anterior hemisphere have the capacity to continuously proliferate and differentiate into lens fiber cells that make up the large proportion of the lens mass. To understand the transcriptional changes that take place during the differentiation process, high-throughput RNA-Seq of newborn mouse lens epithelial cells and lens fiber cells was conducted to comprehensively compare the transcriptomes of these two cell types. Methods RNA from three biologic replicate samples of epithelial and fiber cells from newborn FVB/N mouse lenses was isolated and sequenced to yield more than 24 million reads per sample. Sequence reads that passed quality filtering were mapped to the reference genome using Genomic Short-read Nucleotide Alignment Program (GSNAP). Transcript abundance and differential gene expression were estimated using the Cufflinks and DESeq packages, respectively. Gene Ontology enrichment was analyzed using GOseq. RNA-Seq results were compared with previously published microarray data. The differential expression of several biologically important genes was confirmed using reverse transcription (RT)-quantitative PCR (qPCR). Results Here, we present the first application of RNA-Seq to understand the transcriptional changes underlying the differentiation of epithelial cells into fiber cells in the newborn mouse lens. In total, 6,022 protein-coding genes exhibited differential expression between lens epithelial cells and lens fiber cells. To our knowledge, this is the first study identifying the expression of 254 long intergenic non-coding RNAs (lincRNAs) in the lens, of which 86 lincRNAs displayed differential expression between the two cell types. We found that RNA-Seq identified more differentially expressed genes and correlated with RT-qPCR quantification better than previously published microarray data. Gene Ontology analysis showed that genes

  4. A model for cell density effect on stress fiber alignment and collective directional migration.

    PubMed

    Abeddoust, Mohammad; Shamloo, Amir

    2015-12-31

    In this study, numerical simulation of collective cell migration is presented in order to mimic the group migration of endothelial cells subjected to the concentration gradients of a biochemical factor. The developed 2D model incorporates basic elements of the cell, including both the cell membrane and the cell cytoskeleton, based on a viscoelastic cell mechanic model. Various cell processes--including cell random walk, cell-cell interactions, cell chemotaxis, and cellular cytoskeleton rearrangements--are considered and analyzed in our developed model. After validating the model by using available experimental data, the model is used to investigate various important parameters during collective cell chemotaxis, such as cell density, cytoskeleton organization, stress fiber reorientations, and intracellular forces. The results suggest that increasing the cell density causes the cell-cell interactions to affect the orientation of stress fibers throughout the cytoskeleton and makes the stress fibers more aligned in the direction of the imposed concentration gradient. This improved alignment of the stress fibers correlates with the intensification of the intracellular forces transferred in the gradient direction; this improves the cell group migration. Comparison of the obtained results with available experimental observations of collective chemotaxis of endothelial cells shows an interesting agreement.

  5. A model for cell density effect on stress fiber alignment and collective directional migration

    NASA Astrophysics Data System (ADS)

    Abeddoust, Mohammad; Shamloo, Amir

    2015-12-01

    In this study, numerical simulation of collective cell migration is presented in order to mimic the group migration of endothelial cells subjected to the concentration gradients of a biochemical factor. The developed 2D model incorporates basic elements of the cell, including both the cell membrane and the cell cytoskeleton, based on a viscoelastic cell mechanic model. Various cell processes—including cell random walk, cell-cell interactions, cell chemotaxis, and cellular cytoskeleton rearrangements—are considered and analyzed in our developed model. After validating the model by using available experimental data, the model is used to investigate various important parameters during collective cell chemotaxis, such as cell density, cytoskeleton organization, stress fiber reorientations, and intracellular forces. The results suggest that increasing the cell density causes the cell-cell interactions to affect the orientation of stress fibers throughout the cytoskeleton and makes the stress fibers more aligned in the direction of the imposed concentration gradient. This improved alignment of the stress fibers correlates with the intensification of the intracellular forces transferred in the gradient direction; this improves the cell group migration. Comparison of the obtained results with available experimental observations of collective chemotaxis of endothelial cells shows an interesting agreement.

  6. Development of secondary cell wall in cotton fibers as examined with Fourier transform-infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Our presentation will focus on continuing efforts to examine secondary cell wall development in cotton fibers using infrared Spectroscopy. Cotton fibers harvested at 18, 20, 24, 28, 32, 36 and 40 days after flowering were examined using attenuated total reflection Fourier transform-infrared (ATR FT-...

  7. Compact and Robust Refilling and Connectorization of Hollow Core Photonic Crystal Fiber Gas Reference Cells

    NASA Technical Reports Server (NTRS)

    Poberezhskiy, Ilya Y.; Meras, Patrick; Chang, Daniel H.; Spiers, Gary D.

    2007-01-01

    A simple method for evacuating, refilling and connectorizing hollow-core photonic crystal fiber for use asgas reference cell is proposed and demonstrated. It relies on torch-sealing a quartz filling tube connected to amechanical splice between regular and hollow-core fibers.

  8. Compact and Robust Refilling and Connectorization of Hollow Core Photonic Crystal Fiber Gas Reference Cells

    NASA Technical Reports Server (NTRS)

    Poberezhskiy, Ilya Y.; Meras, Patrick; Chang, Daniel H.; Spiers, Gary D.

    2007-01-01

    A simple method for evacuating, refilling and connectorizing hollow-core photonic crystal fiber for use asgas reference cell is proposed and demonstrated. It relies on torch-sealing a quartz filling tube connected to amechanical splice between regular and hollow-core fibers.

  9. Extent of mossy fiber sprouting in patients with mesiotemporal lobe epilepsy correlates with neuronal cell loss and granule cell dispersion.

    PubMed

    Schmeiser, Barbara; Zentner, Josef; Prinz, Marco; Brandt, Armin; Freiman, Thomas M

    2017-01-01

    The most frequent finding in temporal lobe epilepsy is hippocampal sclerosis, characterized by selective cell loss of hippocampal subregions CA1 and CA4 as well as mossy fiber sprouting (MFS) towards the supragranular region and granule cell dispersion. Although selective cell loss is well described, its impact on mossy fiber sprouting and granule cell dispersion remains unclear. In a single center series, we examined 319 human hippocampal specimens, collected in a 15-years period. Hippocampal specimens were stained for neuronal loss, granule cell dispersion (Wyler scale I-IV, Neu-N, HE) and mossy fiber sprouting (synaptoporin-immunohistochemistry). For seizure outcome Engel score I-IV was applied. In Wyler I and II specimens, mossy fibers were found along their natural projection exclusively in CA4 and CA3. In Wyler III and IV, sprouting of mossy fibers into the molecular layer and a decrease of mossy fibers in CA4 and CA3 was detected. Mean granule cell dispersion was extended from 121μm to 185μm and correlated with Wyler III-IV as well as mossy fiber sprouting into the molecular layer. Wyler grade, mossy fiber sprouting and granule cell dispersion correlated with longer epilepsy duration, late surgery and higher preoperative seizure frequency. Parameters analyzed above did not correlate with postoperative seizure outcome. Mossy fiber sprouting might be a compensatory phenomenon of cell death of the target neurons in CA4 and CA3 in Wyler III-IV. Axonal reorganization of granule cells is accompanied by their migration and is correlated with the severity of cell loss and epilepsy duration. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Topographical effects on fiber-mediated microRNA delivery to control oligodendroglial precursor cells development.

    PubMed

    Diao, Hua Jia; Low, Wei Ching; Lu, Q Richard; Chew, Sing Yian

    2015-11-01

    Effective remyelination in the central nervous system (CNS) facilitates the reversal of disability in patients with demyelinating diseases such as multiple sclerosis. Unfortunately until now, effective strategies of controlling oligodendrocyte (OL) differentiation and maturation remain limited. It is well known that topographical and biochemical signals play crucial roles in modulating cell fate commitment. Therefore, in this study, we explored the combined effects of scaffold topography and sustained gene silencing on oligodendroglial precursor cell (OPC) development. Specifically, microRNAs (miRs) were incorporated onto electrospun polycaprolactone (PCL) fiber scaffolds with different fiber diameters and orientations. Regardless of fiber diameter and orientation, efficient knockdown of differentiation inhibitory factors were achieved by either topography alone (up to 70%) or fibers integrated with miR-219 and miR-338 (up to 80%, p < 0.05). Small fiber promoted OPC differentiation by inducing more RIP(+) cells (p < 0.05) while large fiber promoted OL maturation by inducing more MBP(+) cells (p < 0.05). Random fiber enhanced more RIP(+) cells than aligned fibers (p < 0.05), regardless of fiber diameter. Upon miR-219/miR-338 incorporation, 2 μm aligned fibers supported the most MBP(+) cells (∼17%). These findings indicated that the coupling of substrate topographic cues with efficient gene silencing by sustained microRNA delivery is a promising way for directing OPC maturation in neural tissue engineering and controlling remyelination in the CNS.

  11. Differentiation of pluripotent stem cells to muscle fiber to model Duchenne muscular dystrophy.

    PubMed

    Chal, Jérome; Oginuma, Masayuki; Al Tanoury, Ziad; Gobert, Bénédicte; Sumara, Olga; Hick, Aurore; Bousson, Fanny; Zidouni, Yasmine; Mursch, Caroline; Moncuquet, Philippe; Tassy, Olivier; Vincent, Stéphane; Miyanari, Ayako; Bera, Agata; Garnier, Jean-Marie; Guevara, Getzabel; Hestin, Marie; Kennedy, Leif; Hayashi, Shinichiro; Drayton, Bernadette; Cherrier, Thomas; Gayraud-Morel, Barbara; Gussoni, Emanuela; Relaix, Frédéric; Tajbakhsh, Shahragim; Pourquié, Olivier

    2015-09-01

    During embryonic development, skeletal muscles arise from somites, which derive from the presomitic mesoderm (PSM). Using PSM development as a guide, we establish conditions for the differentiation of monolayer cultures of mouse embryonic stem (ES) cells into PSM-like cells without the introduction of transgenes or cell sorting. We show that primary and secondary skeletal myogenesis can be recapitulated in vitro from the PSM-like cells, providing an efficient, serum-free protocol for the generation of striated, contractile fibers from mouse and human pluripotent cells. The mouse ES cells also differentiate into Pax7(+) cells with satellite cell characteristics, including the ability to form dystrophin(+) fibers when grafted into muscles of dystrophin-deficient mdx mice, a model of Duchenne muscular dystrophy (DMD). Fibers derived from ES cells of mdx mice exhibit an abnormal branched phenotype resembling that described in vivo, thus providing an attractive model to study the origin of the pathological defects associated with DMD.

  12. Fiber diffraction patterns for general unit cells: the cylindrically projected reciprocal lattice

    PubMed

    Finkenstadt; Millane

    1998-03-01

    The positions of reflections on the diffraction pattern from a polycrystalline fiber are described by a cylindrical projection of the reciprocal lattice. The characteristics of the projection depend on the crystal system and the orientation of the fiber axis relative to the unit-cell axes. Expressions describing the cylindrically projected reciprocal lattice for a general triclinic system and any orientation of the fiber axis are derived. Calculations using these expressions illustrate characteristics of the projected reciprocal lattice and aid in the interpretation of fiber diffraction patterns.

  13. Cell Attachment and Viability Study of PCL Nano-fiber Modified by Cold Atmospheric Plasma.

    PubMed

    Atyabi, Seyed Mohammad; Sharifi, Fereshteh; Irani, Shiva; Zandi, Mojgan; Mivehchi, Houri; Nagheh, Zahra

    2016-06-01

    The field of tissue engineering is an emerging discipline which applies the basic principles of life sciences and engineering to repair and restore living tissues and organs. The purpose of this study was to investigate the effect of cold and non-thermal plasma surface modification of poly (ϵ-caprolactone) (PCL) scaffolds on fibroblast cell behavior. Nano-fiber PCL was fabricated through electrospinning technique, and some fibers were then treated by cold and non-thermal plasma. The cell-biomaterial interactions were studied by culturing the fibroblast cells on nano-fiber PCL. Scaffold biocompatibility test was assessed using an inverted microscope. The growth and proliferation of fibroblast cells on nano-fiber PCL were analyzed by MTT viability assay. Cellular attachment on the nano-fiber and their morphology were evaluated using scanning electron microscope. The result of cell culture showed that nano-fiber could support the cellular growth and proliferation by developing three-dimensional topography. The present study demonstrated that the nano-fiber surface modification with cold plasma sharply enhanced the fibroblast cell attachment. Thus, cold plasma surface modification greatly raised the bioactivity of scaffolds.

  14. Mesothelial cell proliferation after instillation of long or short asbestos fibers into mouse lung.

    PubMed Central

    Adamson, I. Y.; Bakowska, J.; Bowden, D. H.

    1993-01-01

    The relationship of asbestos deposition in the lung to subsequent cell proliferation at the pleural surface is not clear. The present study examines DNA synthesis by various pulmonary cells, particularly those at the pleura after intratracheal injection of 0.1 mg crocidolite to mice using: 1) long fibers (> 20 mu), which are deposited in bronchiolar regions and induce fibrosis; 2) short fibers (< 1 mu), which reach alveoli but do not induce fibrosis. Mice also received 2 microCi/g tritiated thymidine 1 hour before death at intervals to 16 weeks. Short fibers induced only a small increase in labeling of bronchiolar epithelial and interstitial cells, which subsided by 5 days, when a small increase in labeled mesothelial and subpleural cells was seen. In contrast, long fibers damaged the bronchiolar epithelium and became incorporated into connective tissue. During regeneration, 12% of cells were labeled at 3 days and labeling was greater than controls to 4 weeks. Increased peribronchiolar labeling of fibroblasts and interstitial macrophages was seen around long fibers, and increased DNA synthesis by mesothelial and subpleural cells was found. Up to 2% of mesothelial cells were labeled 1 week after long fibers compared to near zero in controls. No long fibers were found at the pleura. Activation of interstitial macrophages in response to long crocidolite fibers is associated with fibroblast proliferation. It is now suggested that mesothelial cells may also be stimulated by cytokines from activated interstitial macrophages that diffuse across the interstitium, without requiring actual fiber translocation to the pleura. Images Figure 1 Figure 2 Figure 3 Figure 6 Figure 9 Figure 11 PMID:8475994

  15. Stromal fibers in oral squamous cell carcinoma: A possible new prognostic indicator?

    PubMed Central

    Kardam, Priyanka; Mehendiratta, Monica; Rehani, Shweta; Kumra, Madhumani; Sahay, Khushboo; Jain, Kanu

    2016-01-01

    Background: Many studies have been carried out to study the role of extracellular matrix proteins, growth factors and matrix metalloproteinases on tumor invasion. However, literature related to the analysis of connective tissue fibers in varying grades of oral squamous cell carcinoma (OSCC) is very limited. Aim: To analyze the changes in collagen and elastic fibers in varying grades of (OSCC). Settings and Design: This retrospective study was carried out using a light and polarizing microscope. Materials and Methods: Three sections each were cut from fifty samples of varying grades of OSCC and ten samples of control followed by staining with H and E, Picrosirius-Red and Verhoeff–Van Gieson. Qualitative and quantitative analysis of collagen and elastic fibers were accomplished using set criteria. Statistical Analysis: Data were entered into the Statistical Package for Social Sciences (SPSS) version 13.5 for analysis. Results: A change in colors of collagen fibers was seen on progressing from well to poorly differentiated OSCC. Thin collagen fibers predominantly exhibited greenish yellow, but the thick fibers exhibited a variety of colors. As the grade of OSCC progressed, collagen fibers were loosely packed haphazardly arranged. Statistically insignificant results were obtained for quantitative analysis of collagen and qualitative analysis of elastic fibers. Conclusion: The collagen fibers undergo a change in color, orientation and packing in the stroma of varying grades of OSCC. The uniqueness of this study lies in the exploration of elastic fibers in OSCC which has not been done so far. PMID:27721605

  16. Fiber-based optical trapping for cell mechanics study and microrheology

    NASA Astrophysics Data System (ADS)

    Ti, Chaoyang; Thomas, Gawain M.; Yu, Xiaokong; Wen, Qi; Tao, Mingjiang; Liu, Yuxiang

    2016-09-01

    In this work, we developed fiber based optical trapping system and explored its applications in biology and physics. We aim to replace objective lenses with optical fibers, both for optical trapping and particle position detection. Compared with objective lens based counterparts, fiber based optical trapping systems are small, low-cost, integratable, independent of objective lenses, and can work in turbid mediums. These advantages make fiber optical trapping systems ideal for applications in tightly confined spaces as well as integration with various microscopy techniques. We demonstrate the applications of fiber optical trapping systems in both single-cell mechanics and microrheology study of asphalt binders. Fiber optical trapping system is being used to study mechanical properties of viscoelastic hydrogel, as an important extra cellular matrix (ECM) material that is used to understand the force propagation on cell membranes on 2D substrates or in 3D compartments. Moreover, the fiber optical trapping system has also been demonstrated to measure the cellular response to the external mechanical stimuli. Direct measurements of cellular traction forces in 3D compartments are underway. In addition, fiber optical trapping systems are used to measure the microscale viscoelastic properties of asphalt binders, in order to improve the fundamental understanding of the relationship between mechanical and chemical properties of asphalt binders. This fundamental understanding could help targeted asphalt recycling and pavement maintenance. Fiber optical trapping systems are versatile and highly potential tools that can find applications in various areas ranging from mechanobiology to complex fluids.

  17. Gibberellin Overproduction Promotes Sucrose Synthase Expression and Secondary Cell Wall Deposition in Cotton Fibers

    PubMed Central

    Zhao, Juan; Song, Shui-Qing; Hu, Lin; Zeng, Jian-Yan; Li, Xian-Bi; Hou, Lei; Luo, Ming; Li, De-Mou; Pei, Yan

    2014-01-01

    Bioactive gibberellins (GAs) comprise an important class of natural plant growth regulators and play essential roles in cotton fiber development. To date, the molecular base of GAs' functions in fiber development is largely unclear. To address this question, the endogenous bioactive GA levels in cotton developing fibers were elevated by specifically up-regulating GA 20-oxidase and suppressing GA 2-oxidase via transgenic methods. Higher GA levels in transgenic cotton fibers significantly increased micronaire values, 1000-fiber weight, cell wall thickness and cellulose contents of mature fibers. Quantitative RT-PCR and biochemical analysis revealed that the transcription of sucrose synthase gene GhSusA1 and sucrose synthase activities were significantly enhanced in GA overproducing transgenic fibers, compared to the wild-type cotton. In addition, exogenous application of bioactive GA could promote GhSusA1 expression in cultured fibers, as well as in cotton hypocotyls. Our results suggested that bioactive GAs promoted secondary cell wall deposition in cotton fibers by enhancing sucrose synthase expression. PMID:24816840

  18. Fiber biology

    USDA-ARS?s Scientific Manuscript database

    Cotton fiber cells arising from seed epidermis is the most important agricultural textile commodity in the world. To produce fully mature fibers, approximately two months of fiber developmental process are required. The timing of four distinctive fiber development stages consisting of initiation, ...

  19. Rho and Rab Small G Proteins Coordinately Reorganize Stress Fibers and Focal Adhesions in MDCK Cells

    PubMed Central

    Imamura, Hiroshi; Takaishi, Kenji; Nakano, Katsutoshi; Kodama, Atsuko; Oishi, Hideto; Shiozaki, Hitoshi; Monden, Morito; Sasaki, Takuya; Takai, Yoshimi

    1998-01-01

    The Rho subfamily of the Rho small G protein family (Rho) regulates formation of stress fibers and focal adhesions in many types of cultured cells. In moving cells, dynamic and coordinate disassembly and reassembly of stress fibers and focal adhesions are observed, but the precise mechanisms in the regulation of these processes are poorly understood. We previously showed that 12-O-tetradecanoylphorbol-13-acetate (TPA) first induced disassembly of stress fibers and focal adhesions followed by their reassembly in MDCK cells. The reassembled stress fibers showed radial-like morphology that was apparently different from the original. We analyzed here the mechanisms of these TPA-induced processes. Rho inactivation and activation were necessary for the TPA-induced disassembly and reassembly, respectively, of stress fibers and focal adhesions. Both inactivation and activation of the Rac subfamily of the Rho family (Rac) inhibited the TPA-induced reassembly of stress fibers and focal adhesions but not their TPA-induced disassembly. Moreover, microinjection or transient expression of Rab GDI, a regulator of all the Rab small G protein family members, inhibited the TPA-induced reassembly of stress fibers and focal adhesions but not their TPA-induced disassembly, indicating that, furthermore, activation of some Rab family members is necessary for their TPA-induced reassembly. Of the Rab family members, at least Rab5 activation was necessary for the TPA-induced reassembly of stress fibers and focal adhesions. The TPA-induced, small G protein-mediated reorganization of stress fibers and focal adhesions was closely related to the TPA-induced cell motility. These results indicate that the Rho and Rab family members coordinately regulate the TPA-induced reorganization of stress fibers and focal adhesions that may cause cell motility. PMID:9725912

  20. The Hagfish Gland Thread Cell: A Fiber-Producing Cell Involved in Predator Defense

    PubMed Central

    Fudge, Douglas S.; Schorno, Sarah

    2016-01-01

    Fibers are ubiquitous in biology, and include tensile materials produced by specialized glands (such as silks), extracellular fibrils that reinforce exoskeletons and connective tissues (such as chitin and collagen), as well as intracellular filaments that make up the metazoan cytoskeleton (such as F-actin, microtubules, and intermediate filaments). Hagfish gland thread cells are unique in that they produce a high aspect ratio fiber from cytoskeletal building blocks within the confines of their cytoplasm. These threads are elaborately coiled into structures that readily unravel when they are ejected into seawater from the slime glands. In this review we summarize what is currently known about the structure and function of gland thread cells and we speculate about the mechanism that these cells use to produce a mechanically robust fiber that is almost one hundred thousand times longer than it is wide. We propose that a key feature of this mechanism involves the unidirectional rotation of the cell’s nucleus, which would serve to twist disorganized filaments into a coherent thread and impart a torsional stress on the thread that would both facilitate coiling and drive energetic unravelling in seawater. PMID:27258313

  1. A fast platform for simulating semi-flexible fiber suspensions applied to cell mechanics

    NASA Astrophysics Data System (ADS)

    Nazockdast, Ehssan; Rahimian, Abtin; Zorin, Denis; Shelley, Michael

    2017-01-01

    We present a novel platform for the large-scale simulation of three-dimensional fibrous structures immersed in a Stokesian fluid and evolving under confinement or in free-space in three dimensions. One of the main motivations for this work is to study the dynamics of fiber assemblies within biological cells. For this, we also incorporate the key biophysical elements that determine the dynamics of these assemblies, which include the polymerization and depolymerization kinetics of fibers, their interactions with molecular motors and other objects, their flexibility, and hydrodynamic coupling. This work, to our knowledge, is the first technique to include many-body hydrodynamic interactions (HIs), and the resulting fluid flows, in cellular assemblies of flexible fibers. We use non-local slender body theory to compute the fluid-structure interactions of the fibers and a second-kind boundary integral formulation for other rigid bodies and the confining boundary. A kernel-independent implementation of the fast multipole method is utilized for efficient evaluation of HIs. The deformation of the fibers is described by nonlinear Euler-Bernoulli beam theory and their polymerization is modeled by the reparametrization of the dynamic equations in the appropriate non-Lagrangian frame. We use a pseudo-spectral representation of fiber positions and implicit time-stepping to resolve large fiber deformations, and to allow time-steps not excessively constrained by temporal stiffness or fiber-fiber interactions. The entire computational scheme is parallelized, which enables simulating assemblies of thousands of fibers. We use our method to investigate two important questions in the mechanics of cell division: (i) the effect of confinement on the hydrodynamic mobility of microtubule asters; and (ii) the dynamics of the positioning of mitotic spindle in complex cell geometries. Finally to demonstrate the general applicability of the method, we simulate the sedimentation of a cloud of

  2. Mesoscopic Adaptive Resolution Scheme toward Understanding of Interactions between Sickle Cell Fibers.

    PubMed

    Lu, Lu; Li, He; Bian, Xin; Li, Xuejin; Karniadakis, George Em

    2017-07-11

    Understanding of intracellular polymerization of sickle hemoglobin (HbS) and subsequent interaction with the membrane of a red blood cell (RBC) is important to predict the altered morphologies and mechanical properties of sickle RBCs in sickle cell anemia. However, modeling the integrated processes of HbS nucleation, polymerization, HbS fiber interaction, and subsequent distortion of RBCs is challenging as they occur at multispatial scales, ranging from nanometers to micrometers. To make progress toward simulating the integrated processes, we propose a hybrid HbS fiber model, which couples fine-grained and coarse-grained HbS fiber models through a mesoscopic adaptive resolution scheme (MARS). To this end, we apply a microscopic model to capture the dynamic process of polymerization of HbS fibers, while maintaining the mechanical properties of polymerized HbS fibers by the mesoscopic model, thus providing a means of bridging the subcellular and cellular phenomena in sickle cell disease. At the subcellular level, this model can simulate HbS polymerization with preexisting HbS nuclei. At the cellular level, if combined with RBC models, the generated HbS fibers could be applied to study the morphologies and membrane stiffening of sickle RBCs. One important feature of the MARS is that it can be easily employed in other particle-based multiscale simulations where a dynamic coarse-graining and force-blending method is required. As demonstrations, we first apply the hybrid HbS fiber model to simulate the interactions of two growing fibers and find that their final configurations depend on the orientation and interaction distance between two fibers, in good agreement with experimental observations. We also model the formation of fiber bundles and domains so that we explore the mechanism that causes fiber branching. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  3. Kinetochore fiber formation in animal somatic cells: dueling mechanisms come to a draw

    PubMed Central

    2008-01-01

    The attachment to and movement of a chromosome on the mitotic spindle are mediated by the formation of a bundle of microtubules (MTs) that tethers the kinetochore on the chromosome to a spindle pole. The origin of these “kinetochore fibers” (K fibers) has been investigated for over 125 years. As noted in 1944 by Schrader [Mitosis, Columbia University Press, New York, 110 pp.], there are three possible ways to form a K fiber: (a) it grows from the pole until it contacts the kinetochore, (b) it grows directly from the kinetochore, or (c) it forms as a result of an interaction between the pole and the chromosome. Since Schrader's time, it has been firmly established that K fibers in centrosome-containing animal somatic cells form as kinetochores capture MTs growing from the spindle pole (route a). It is now similarly clear that in cells lacking centrosomes, including higher plants and many animal oocytes, K fibers “self-assemble” from MTs generated by the chromosomes (route b). Can animal somatic cells form K fibers in the absence of centrosomes by the “self-assembly” pathway? In 2000, the answer to this question was shown to be a resounding “yes.” With this result, the next question became whether the presence of a centrosome normally suppresses K fiber self-assembly or if this route works concurrently with centrosome-mediated K-fiber formation. This question, too, has recently been answered: observations on untreated live animal cells expressing green fluorescent protein-tagged tubulin clearly show that kinetochores can nucleate the formation of their associated MTs in a unique manner in the presence of functional centrosomes. The concurrent operation of these two “dueling” routes for forming K fibers in animal cells helps explain why the attachment of kinetochores and the maturation of K fibers occur as quickly as they do on all chromosomes within a cell. PMID:16270218

  4. Effects of extracellular fiber architecture on cell membrane shear stress in a 3D fibrous matrix.

    PubMed

    Pedersen, John A; Boschetti, Federica; Swartz, Melody A

    2007-01-01

    Interstitial fluid flow has been shown to affect the organization and behavior of cells in 3D environments in vivo and in vitro, yet the forces driving such responses are not clear. Due to the complex architecture of the extracellular matrix (ECM) and the difficulty of measuring fluid flow near cells embedded in it, the levels of shear stress experienced by cells in this environment are typically estimated using bulk-averaged matrix parameters such as hydraulic permeability. While this is useful for estimating average stresses, it cannot yield insight into how local matrix fiber architecture-which is cell-controlled in the immediate pericellular environment-affects the local stresses imposed on the cell surface. To address this, we used computational fluid dynamics to study flow through an idealized mesh constructed of a cubic lattice of fibers simulating a typical in vitro collagen gel. We found that, in such high porosity matrices, the fibers strongly affect the flow fields near the cell, with peak shear stresses up to five times higher than those predicted by the Brinkman equation. We also found that minor remodeling of the fibers near the cell surface had major effects on the shear stress profile on the cell. These findings demonstrate the importance of fiber architecture to the fluid forces on a cell embedded in a 3D matrix, and also show how small modifications in the local ECM can lead to large changes in the mechanical environment of the cell.

  5. Fiber-optic Raman sensing of cell proliferation probes and molecular vibrations: Brain-imaging perspective

    NASA Astrophysics Data System (ADS)

    Doronina-Amitonova, Lyubov V.; Fedotov, Il'ya V.; Ivashkina, Olga I.; Zots, Marina A.; Fedotov, Andrei B.; Anokhin, Konstantin V.; Zheltikov, Aleksei M.

    2012-09-01

    Optical fibers are employed to sense fingerprint molecular vibrations in ex vivo experiments on the whole brain and detect cell proliferation probes in a model study on a quantitatively controlled solution. A specifically adapted spectral filtering procedure is shown to allow the Raman signal from molecular vibrations of interest to be discriminated against the background from the fiber, allowing a highly sensitive Raman detection of the recently demonstrated EdU (5-ethynyl-2'-deoxyuridine) labels of DNA synthesis in cells.

  6. N-cadherin regulates signaling mechanisms required for lens fiber cell elongation and lens morphogenesis.

    PubMed

    Logan, Caitlin M; Rajakaruna, Suren; Bowen, Caitlin; Radice, Glenn L; Robinson, Michael L; Menko, A Sue

    2017-08-01

    Tissue development and regeneration involve high-ordered morphogenetic processes that are governed by elements of the cytoskeleton in conjunction with cell adhesion molecules. Such processes are particularly important in the lens whose structure dictates its function. Studies of our lens-specific N-cadherin conditional knockout mouse (N-cadcKO) revealed an essential role for N-cadherin in the migration of the apical tips of differentiating lens fiber cells along the apical surfaces of the epithelium, a region termed the Epithelial Fiber Interface (EFI), that is necessary for normal fiber cell elongation and the morphogenesis. Studies of the N-cadcKO lens suggest that N-cadherin function in fiber cell morphogenesis is linked to the activation of Rac1 and myosin II, both signaling pathways central to the regulation of cell motility including determining the directionality of cellular movement. The absence of N-cadherin did not disrupt lateral contacts between fiber cells during development, and the maintenance of Aquaporin-0 and increased expression of EphA2 at cell-cell interfaces suggests that these molecules may function in this role. E-cadherin was maintained in newly differentiating fiber cells without interfering with expression of lens-specific differentiation proteins but was not able to replace N-cadherin function in these cells. The dependence of migration of the fiber cell apical domains along the EFI for lens morphogenesis on N-cadherin provides new insight into the process of tissue development. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Purkinje cell stripes and long-term depression at the parallel fiber-Purkinje cell synapse

    PubMed Central

    Hawkes, Richard

    2014-01-01

    The cerebellar cortex comprises a stereotyped array of transverse zones and parasagittal stripes, built around multiple Purkinje cell subtypes, which is highly conserved across birds and mammals. This architecture is revealed in the restricted expression patterns of numerous molecules, in the terminal fields of the afferent projections, in the distribution of interneurons, and in the functional organization. This review provides an overview of cerebellar architecture with an emphasis on attempts to relate molecular architecture to the expression of long-term depression (LTD) at the parallel fiber-Purkinje cell (pf-PC) synapse. PMID:24734006

  8. Removing PAH`s with cells on fibers

    SciTech Connect

    Clyde, R.

    1996-12-31

    There are over 1,500 sites contaminated with polycyclic aromatic hydrocarbons from coal gas plants. White rot fungi degrade PAH`s in soil, but the problem is to supply oxygen needed for growth of the fungus. When old cardboard boxes are buried with the fungus, oxygen is entrapped in the corrugations. A method for growing the fungus quickly is also described. Pseudomonade also degrade PAH and several strains of this bacterium have been grown on fibers. The fibers have high area, and when Celite is entrapped in the fibers, more area is provided.

  9. Molecular markers associated with the immature fiber (im) gene affecting the degree of fiber cell wall thickening in cotton (Gossypium hirsutum L.).

    PubMed

    Kim, Hee Jin; Moon, Hong S; Delhom, Christopher D; Zeng, Linghe; Fang, David D

    2013-01-01

    Cotton fiber fineness and maturity measured indirectly as micronaire (MIC) are important properties of determining fiber grades in the textile market. To understand the genetic control and molecular mechanisms of fiber fineness and maturity, we studied two near isogenic lines, Gossypium hirsutum, Texas Marker-1 wild type (TM-1) and immature fiber (im) mutant showing a significant difference in MIC values. The fibers from im mutant plants were finer and less mature with lower MIC values than those from the recurrent parent, TM-1. A comprehensive fiber property analysis of TM-1 and im mutant showed that the lower MIC of fibers in im mutant was due to the lower degree of fiber cell wall thickening as compared to the TM-1 fibers. Using an F(2) population comprising 366 progenies derived from a cross between TM-1 and im mutant, we confirmed that the immature fiber phenotype present in a mutant plant was controlled by one single recessive gene im. Furthermore, we identified 13 simple sequence repeat markers that were closely linked to the im gene located on chromosome 3. Molecular markers associated with the im gene will lay the foundation to further investigate genetic information required for improving cotton fiber fineness and maturity.

  10. Solid-state, polymer-based fiber solar cells with carbon nanotube electrodes.

    PubMed

    Liu, Dianyi; Zhao, Mingyan; Li, Yan; Bian, Zuqiang; Zhang, Luhui; Shang, Yuanyuan; Xia, Xinyuan; Zhang, Sen; Yun, Daqin; Liu, Zhiwei; Cao, Anyuan; Huang, Chunhui

    2012-12-21

    Most previous fiber-shaped solar cells were based on photoelectrochemical systems involving liquid electrolytes, which had issues such as device encapsulation and stability. Here, we deposited classical semiconducting polymer-based bulk heterojunction layers onto stainless steel wires to form primary electrodes and adopted carbon nanotube thin films or densified yarns to replace conventional metal counter electrodes. The polymer-based fiber cells with nanotube film or yarn electrodes showed power conversion efficiencies in the range 1.4% to 2.3%, with stable performance upon rotation and large-angle bending and during long-time storage without further encapsulation. Our fiber solar cells consisting of a polymeric active layer sandwiched between steel and carbon electrodes have potential in the manufacturing of low-cost, liquid-free, and flexible fiber-based photovoltaics.

  11. Disassembly of the lens fiber cell nucleus to create a clear lens: the p27 descent

    USDA-ARS?s Scientific Manuscript database

    The eye lens is unique among tissues: it is transparent, does not form tumors, and the majority of its cells degrade their organelles, including their cell nuclei. A mystery for over a century, there has been considerable recent progress in elucidating mechanisms of lens fiber cell denucleation (LFC...

  12. Beta-1 integrin is important for the structural maintenance and homeostasis of differentiating fiber cells

    PubMed Central

    Scheiblin, David A.; Gao, Junyuan; Caplan, Jeffrey L.; Simirskii, Vladimir N.; Czymmek, Kirk J.; Mathias, Richard T.; Duncan, Melinda K.

    2014-01-01

    β1-integrin is a heterodimeric transmembrane protein that has roles in both cell-extracellular matrix and cell-cell interactions. Conditional deletion of β1-integrin from all lens cells during embryonic development results in profound lens defects, however, it is less clear whether this reflects functions in the lens epithelium alone or whether this protein plays a role in lens fibers. Thus, a conditional approach was used to delete β1-integrin solely from the lens fiber cells. This deletion resulted in two distinct phenotypes with some lenses exhibiting cataracts while others were clear, albeit with refractive defects. Analysis of “clear” conditional knockout lenses revealed that they had profound defects in fiber cell morphology associated with the loss of the F-actin network. Physiological measurements found that the lens fiber cells had a two-fold increase in gap junctional coupling, perhaps due to differential localization of connexins 46 and 50, as well as increased water permeability. This would presumably facilitate transport of ions and nutrients through the lens, and may partially explain how lenses with profound structural abnormalities can maintain transparency. In summary, β1-integrin plays a role in maintaining the cellular morphology and homeostasis of the lens fiber cells. PMID:24607497

  13. Coding channels for taste perception: information transmission from taste cells to gustatory nerve fibers.

    PubMed

    Yoshida, Ryusuke; Yasumatsu, Keiko; Shigemura, Noriatsu; Ninomiya, Yuzo

    2006-12-01

    Taste signals are first detected by the taste receptor cells, which are located in taste buds existing in the tongue, soft palate, larynx and epiglottis. Taste receptor cells contact with the chemical compounds in oral cavity through the apical processes which protrude into the taste pore. Interaction between chemical compounds and the taste receptor produces activation of taste receptor cells directly or indirectly. Then the signals are transmitted to gustatory nerve fibers and higher order neurons. A recent study demonstrated many similarities between response properties of taste receptor cells with action potentials and those of the gustatory nerve fibers innervating them, suggesting information derived from receptor cells generating action potentials may form a major component of taste information that is transmitted to gustatory nerve fibers. These findings may also indicate that there is no major modification of taste information sampled by taste receptor cells in synaptic transmission from taste cells to nerve fibers although there is indirect evidence. In the peripheral taste system, gustatory nerve fibers may selectively contact with taste receptor cells that have similar response properties and convey constant taste information to the higher order neurons.

  14. Unique and Analogous Functions of Aquaporin 0 for Fiber Cell Architecture and Ocular Lens Transparency

    PubMed Central

    Kumari, S. Sindhu; Eswaramoorthy, Subramaniam; Mathias, Richard T.; Varadaraj, Kulandaiappan

    2011-01-01

    Aquaporin (AQP) 1 and AQP0 water channels are expressed in lens epithelial and fiber cells, respectively, facilitating fluid circulation for nourishing the avascular lens to maintain transparency. Even though AQP0 water permeability is 40-fold less than AQP1, AQP0 is selectively expressed in the fibers. Delimited AQP0 fiber expression is attributed to a unique structural role as an adhesion protein. To validate this notion, we determined if wild type (WT) lens ultrastructure and fiber cell adhesion are different in AQP0−/−, and TgAQP1+/+/AQP0−/− mice that transgenically express AQP1 (TgAQP1) in fiber cells without AQP0 (AQP0−/−). In WT, lenses were transparent with ‘Y’ sutures. Fibers contained opposite end curvature, lateral interdigitations and hexagonal shape, and were arranged as concentric growth shells. AQP0−/− lenses were cataractous, lacked ‘Y’ sutures, ordered packing and well-defined lateral interdigitations. TgAQP1+/+/AQP0−/− lenses showed improvement in transparency and lateral interdigitations in the outer cortex while inner cortex and nuclear fibers were severely disintegrated. Transmission electron micrographs exhibited tightly packed fiber cells in WT whereas AQP0−/− and TgAQP1+/+/AQP0−/− lenses had wide extracellular spaces. Fibers were easily separable by teasing in AQP0−/− and TgAQP1+/+/AQP0−/− lenses compared to WT. Our data suggest that the increased water permeability through AQP1 does not compensate for loss of AQP0 expression in TgAQP1+/+/AQP0−/− mice. Fiber cell AQP0 expression is required to maintain their organization, which is a requisite for lens transparency. AQP0 appears necessary for cell-to-cell adhesion and thereby to minimize light scattering since in the AQP0−/− and TgAQP1+/+/AQP0−/− lenses, fiber cell disorganization was evident. PMID:21511033

  15. Induction of heme oxygenase in mammalian cells by mineral fibers: distinctive effect of reactive oxygen species.

    PubMed

    Suzuki, K; Hei, T K

    1996-04-01

    Exponentially growing human-hamster hybrid [AL] cells treated with a 40 micrograms/ml (8 micrograms/cm2) dose of UICC standard reference chrysotile fibers induced heme oxygenase (HO) protein with a maximum expression level at 8 h post-treatment. While the constitutive HO expression was detectable in non-treated AL cells, the protein level was increased approximately 4.5-fold in fiber-treated cells. The induction was dose-dependent at fiber concentration between 2.5 micrograms/ml (0.5 microgram/cm2) and 40 micrograms/ml (8 micrograms/cm2) with the induced HO concentrated mostly in the cytoplasm as shown by immunostaining. Several other types of mineral fibers examined including crocidolites, tremolites, and erionites also induced HO synthesis with varying degree of efficiency. In general, chrysotile and crocidolite were more efficient inducers of HO than tremolite and erionite when compared at fiber doses that resulted in approximately 50% survival (LD50) level. The effects of antioxidant enzymes on HO induction were examined by concurrent treatment of fiber-exposed cultures with SOD and catalase. Although addition of superoxide dismutase (SOD) and catalase inhibited HO induction in a dose-dependent manner, they offered no protection on fiber-mediated clonogenic toxicity in the same population of treated cells. These results suggest that reactive oxygen species (ROS) produced by asbestos fibers play an essential role in the induction of HO and that different mineral fibers, when applied at equitoxic doses, often result in different oxidative stress status as determined by the induction of HO proteins.

  16. Heteromannan and Heteroxylan Cell Wall Polysaccharides Display Different Dynamics During the Elongation and Secondary Cell Wall Deposition Phases of Cotton Fiber Cell Development

    PubMed Central

    Hernandez-Gomez, Mercedes C.; Runavot, Jean-Luc; Guo, Xiaoyuan; Bourot, Stéphane; Benians, Thomas A.S.; Willats, William G.T.; Meulewaeter, Frank; Knox, J. Paul

    2015-01-01

    The roles of non-cellulosic polysaccharides in cotton fiber development are poorly understood. Combining glycan microarrays and in situ analyses with monoclonal antibodies, polysaccharide linkage analyses and transcript profiling, the occurrence of heteromannan and heteroxylan polysaccharides and related genes in developing and mature cotton (Gossypium spp.) fibers has been determined. Comparative analyses on cotton fibers at selected days post-anthesis indicate different temporal and spatial regulation of heteromannan and heteroxylan during fiber development. The LM21 heteromannan epitope was more abundant during the fiber elongation phase and localized mainly in the primary cell wall. In contrast, the AX1 heteroxylan epitope occurred at the transition phase and during secondary cell wall deposition, and localized in both the primary and the secondary cell walls of the cotton fiber. These developmental dynamics were supported by transcript profiling of biosynthetic genes. Whereas our data suggest a role for heteromannan in fiber elongation, heteroxylan is likely to be involved in the regulation of cellulose deposition of secondary cell walls. In addition, the relative abundance of these epitopes during fiber development varied between cotton lines with contrasting fiber characteristics from four species (G. hirsutum, G. barbadense, G. arboreum and G. herbaceum), suggesting that these non-cellulosic polysaccharides may be involved in determining final fiber quality and suitability for industrial processing. PMID:26187898

  17. Scalable air cathode microbial fuel cells using glass fiber separators, plastic mesh supporters, and graphite fiber brush anodes.

    PubMed

    Zhang, Xiaoyuan; Cheng, Shaoan; Liang, Peng; Huang, Xia; Logan, Bruce E

    2011-01-01

    The combined use of brush anodes and glass fiber (GF1) separators, and plastic mesh supporters were used here for the first time to create a scalable microbial fuel cell architecture. Separators prevented short circuiting of closely-spaced electrodes, and cathode supporters were used to avoid water gaps between the separator and cathode that can reduce power production. The maximum power density with a separator and supporter and a single cathode was 75 ± 1 W/m(3). Removing the separator decreased power by 8%. Adding a second cathode increased power to 154 ± 1 W/m(3). Current was increased by connecting two MFCs connected in parallel. These results show that brush anodes, combined with a glass fiber separator and a plastic mesh supporter, produce a useful MFC architecture that is inherently scalable due to good insulation between the electrodes and a compact architecture.

  18. Preparation of adult muscle fiber-associated stem/precursor cells.

    PubMed

    Conboy, Michael J; Conboy, Irina M

    2010-01-01

    In our studies of muscle regeneration we have developed, modified, and optimized techniques to isolate and study the stem and precursor cells to muscle tissue. Our goals have been to obtain for study muscle fibers in bulk, or the fiber-associated cells, separately from the other cells found in muscle. Using these techniques, myofiber-associated cells may be isolated from neonatal through adult muscle, from resting or from regenerating muscle, thus allowing one to investigate the cellular populations participating during the time course of these events. The protocol is applicable to any age and condition of muscle and may be adapted for other tissues.

  19. Eccentric exercise increases satellite cell content in type II muscle fibers.

    PubMed

    Cermak, Naomi M; Snijders, Tim; McKay, Bryon R; Parise, Gianni; Verdijk, Lex B; Tarnopolsky, Mark A; Gibala, Martin J; Van Loon, Luc J C

    2013-02-01

    Satellite cells (SCs) are of key importance in skeletal muscle tissue growth, repair, and regeneration. A single bout of high-force eccentric exercise has been demonstrated to increase mixed muscle SC content after 1-7 d of postexercise recovery. However, little is known about fiber type-specific changes in SC content and their activation status within 24 h of postexercise recovery. Nine recreationally active young men (23 ± 1 yr) performed 300 eccentric actions of the knee extensors on an isokinetic dynamometer. Skeletal muscle biopsies from the vastus lateralis were collected preexercise and 24 h postexercise. Muscle fiber type-specific SC content and the number of activated SCs were determined by immunohistochemical analyses. There was no difference between Type I and Type II muscle fiber SC content before exercise. SC content significantly increased 24 h postexercise in Type II muscle fibers (from 0.085 ± 0.012 to 0.133 ± 0.016 SCs per fiber, respectively; P < 0.05), whereas there was no change in Type I fibers. In accordance, activation status increased from preexercise to 24 h postexercise as demonstrated by the increase in the number of DLK1+ SCs in Type II muscle fibers (from 0.027 ± 0.008 to 0.070 ± 0.017 SCs per muscle fiber P < 0.05). Although no significant changes were observed in the number of Ki-67+ SCs, we did observe an increase in the number of proliferating cell nuclear antigen-positive SCs after 24 h of postexercise recovery. A single bout of high-force eccentric exercise increases muscle fiber SC content and activation status in Type II but not Type I muscle fibers.

  20. Retinal flat cells are a substrate that facilitates retinal neuron growth and fiber formation.

    PubMed

    Li, H P; Sheffield, J B

    1986-03-01

    When embryonic chick neural retinas are dissociated into a suspension of single cells and plated in stationary cultures, "flat cells" spread out and form a monolayer to which the neuronal cells attach. It has been shown previously that the flat cells are related to the Müller cell population of the retina. The neuronal cells form aggregates interconnected by bundles of axon-like fibers. The authors have been able to isolate relatively pure flat cells by shaking off the neuronal aggregates after 5 or 6 days of culture. In order to determine if the flat cells have a unique relationship with the neuronal cells, freshly dissociated neural retina cells were added to monolayers of flat cells and their behavior compared to that on chick embryo mesodermal cells. It has been observed by phase contrast and scanning electron microscopy that the growth behavior of the retina cells on flat cells is significantly different from that on mesodermal cells. On flat cells, neuronal retina cells form flat patches in which new growing flat cells fuse with the monolayer, and neuronal cells attach as single cells or small clusters. Axon-like fibers are present several hours after plating, and by day 4 an extensive network of fibers connects single cells and clusters on the surface of the monolayer. When retina cells are plated onto mesodermal cells, the cells form aggregates which are organized along the long axis of the mesodermal cells. The flat cells provide a unique substrate for the differentiation and neurite extension of neuronal cells from embryonic chick retina.

  1. Cell-type-dependent enzymatic hydrolysis of palm residues: chemical and surface characterization of fibers and parenchyma cells.

    PubMed

    Li, Ning; Liu, Hao; Fu, Shiyu; Chen, Shicheng

    2013-02-01

    Chemical and surface characteristics of sulfite-pretreated royal palm sheath (RPS) fibers and parenchyma cells were investigated in order to study cell-type-dependent biomass hydrolysis by cellulase. Size, chemical composition, cellulose crystallinity and the exposure of cellulose microfibrils in pretreated RPS biomass affected the enzymatic accessibility and digestibility of different cell-type substrates.

  2. Rechargeable lithium-ion cells using graphitized mesophase-pitch-based carbon fiber anodes

    SciTech Connect

    Takami, Norio; Satoh, Asako; Hara, Michikazu; Ohsaki, Takahisa

    1995-08-01

    The electrochemistry of lithium intercalation into a graphitized mesophase-pitch-based carbon fiber with a radial-like texture used as the anode material in rechargeable lithium-ion cells was characterized. The radial-like texture in the cross section of the carbon fiber contributed to the rapid diffusion of lithium ions, resulting in the high rate capability. The anode performance of the graphitized carbon fiber was superior to that of the graphite. Experimental flat-plate C/LiCoO{sub 2} lithium-ion cells using the graphitized carbon fiber anode exhibited a high mid-discharge voltage of 3.7 V, a high rate capability, and a long cycle life of more than 400 cycles at 2 mA/cm{sup 2} mA/cm{sup 2} during charge-discharge cycling between 4.2 and 2.7 V. The long cycle life obtained for the cell was due to no significant change in resistance associated with the passivating films on the graphitized carbon fiber with extended cycles. It was also demonstrated that A size C/LiCoO{sub 2} cells using the graphitized carbon fiber anode have excellent rate performance at discharge currents between 0.25 and 3 A, a large discharge capacity of 0.95 Ah, and a high energy density of 310 Wh/dm{sup 3} and 120 Wh/kg.

  3. Effect of dietary fibers on losartan uptake and transport in Caco-2 cells.

    PubMed

    Iwazaki, Ayano; Takahashi, Naho; Miyake, Reiko; Hiroshima, Yuka; Abe, Mariko; Yasui, Airi; Imai, Kimie

    2016-05-01

    The objective of this study was to assess the effect of dietary fibers on the transport of losartan, an angiotensin II type 1 receptor blocker, in small intestinal cells. Using Caco-2 cells in vitro, losartan uptake and transport were evaluated in the presence of various fibers (cellulose, chitosan, sodium alginate and glucomannan). Dietary fibers caused a decrease in the uptake of losartan, with chitosan causing a significant reduction. Chitosan and glucomannan significantly reduced the transport of losartan, while cellulose or sodium alginate did not. Dietary fibers also reduced the level of free losartan; however, this did not correlate with the observed reduction in losartan uptake and transport. In summary, chitosan had the greatest inhibitory effect on losartan uptake and transport, and this potential interaction should be considered in patients taking losartan. Copyright © 2016 John Wiley & Sons, Ltd.

  4. Local alignment vectors reveal cancer cell-induced ECM fiber remodeling dynamics.

    PubMed

    Lee, Byoungkoo; Konen, Jessica; Wilkinson, Scott; Marcus, Adam I; Jiang, Yi

    2017-01-03

    Invasive cancer cells interact with the surrounding extracellular matrix (ECM), remodeling ECM fiber network structure by condensing, degrading, and aligning these fibers. We developed a novel local alignment vector analysis method to quantitatively measure collagen fiber alignment as a vector field using Circular Statistics. This method was applied to human non-small cell lung carcinoma (NSCLC) cell lines, embedded as spheroids in a collagen gel. Collagen remodeling was monitored using second harmonic generation imaging under normal conditions and when the LKB1-MARK1 pathway was disrupted through RNAi-based approaches. The results showed that inhibiting LKB1 or MARK1 in NSCLC increases the collagen fiber alignment and captures outward alignment vectors from the tumor spheroid, corresponding to high invasiveness of LKB1 mutant cancer cells. With time-lapse imaging of ECM micro-fiber morphology, the local alignment vector can measure the dynamic signature of invasive cancer cell activity and cell-migration-induced ECM and collagen remodeling and realigning dynamics.

  5. Local alignment vectors reveal cancer cell-induced ECM fiber remodeling dynamics

    PubMed Central

    Lee, Byoungkoo; Konen, Jessica; Wilkinson, Scott; Marcus, Adam I.; Jiang, Yi

    2017-01-01

    Invasive cancer cells interact with the surrounding extracellular matrix (ECM), remodeling ECM fiber network structure by condensing, degrading, and aligning these fibers. We developed a novel local alignment vector analysis method to quantitatively measure collagen fiber alignment as a vector field using Circular Statistics. This method was applied to human non-small cell lung carcinoma (NSCLC) cell lines, embedded as spheroids in a collagen gel. Collagen remodeling was monitored using second harmonic generation imaging under normal conditions and when the LKB1-MARK1 pathway was disrupted through RNAi-based approaches. The results showed that inhibiting LKB1 or MARK1 in NSCLC increases the collagen fiber alignment and captures outward alignment vectors from the tumor spheroid, corresponding to high invasiveness of LKB1 mutant cancer cells. With time-lapse imaging of ECM micro-fiber morphology, the local alignment vector can measure the dynamic signature of invasive cancer cell activity and cell-migration-induced ECM and collagen remodeling and realigning dynamics. PMID:28045069

  6. Sorbitol and gluconic acid production using permeabilized zymomonas mobilis cells confined by hollow-fiber membranes.

    PubMed

    Ferraz, H C; Borges, C P; Alves, T L

    2000-10-01

    Immobilization of Zymomonas mobilis by different methods was investigated. Experiments were performed in order to choose the most appropriate support for the immobilization of the cells. The most advantageous option was to use permeabilized cells in the bore of microporous hollow fibers. Whereas the reaction rate was about 33 g of gluconate/(g of protein x h) using hollow fibers, which is comparable to that observed by using free cells, the calcium alginate immobilized cells presented a reaction rate of 4 g of gluconate/(g of protein x h). These results can be explained by the mass transfer resistance effect, which, indeed, was much lower in the case of hollow-fiber membranes than in the alginate gel beads. A loss of enzymatic activity during the reaction was observed in all experiments, which was attributed to the lactone produced as an intermediate of the reaction.

  7. Processing and properties of multiscale cellular thermoplastic fiber reinforced composite (CellFRC)

    NASA Astrophysics Data System (ADS)

    Sorrentino, L.; Cafiero, L.; D'Auria, M.; Iannace, S.

    2015-12-01

    High performance fiber reinforced polymer composites are made by embedding high strength/modulus fibers in a polymeric matrix. They are a class of materials that owe its success to the impressive specific mechanical properties with respect to metals. In many weight-sensitive applications, where high mechanical properties and low mass are required, properties per unit of mass are more important than absolute properties and further weight reduction is desirable. A route to reach this goal could be the controlled induction of porosity into the polymeric matrix, while still ensuring load transfer to the reinforcing fibers and fiber protection from the environment. Cellular lightweight fiber reinforced composites (CellFRC) were prepared embedding gas bubbles of controlled size within a high performance thermoplastic matrix reinforced with continuous fibers. Pores were induced after the composite was first saturated with CO2 and then foamed by using an in situ foaming/shaping technology based on compression moulding with adjustable mould cavities. The presence of micro- or submicro-sized cells in the new CellFRC reduced the apparent density of the structure and led to significant improvements of its impact properties. Both structural and functional performances were further improved through the use of a platelet-like nanofiller (Expanded Graphite) dispersed into the matrix.

  8. Effect of polyvinylidene fluoride electrospun fiber orientation on neural stem cell differentiation.

    PubMed

    Lins, Luanda C; Wianny, Florence; Livi, Sebastien; Dehay, Colette; Duchet-Rumeau, Jannick; Gérard, Jean-François

    2016-08-29

    Electrospun polymer piezoelectric fibers can be used in neural tissue engineering (NTE) to mimic the physical, biological, and material properties of the native extracellular matrix. In this work, we have developed scaffolds based on polymer fiber architectures for application in NTE. To study the role of such three-dimensional scaffolds, a rotating drum collector was used for electrospinning poly(vinylidene) fluoride (PVDF) polymer at various rotation speeds. The morphology, orientation, polymorphism, as well as the mechanical behavior of the nonaligned and aligned fiber-based architectures were characterized. We have demonstrated that the jet flow and the electrostatic forces generated by electrospinning of PVDF induced local conformation changes which promote the generation of the β-phase. Fiber anisotropy could be a critical feature for the design of suitable scaffolds for NTEs. We thus assessed the impact of PVDF fiber alignment on the behavior of monkey neural stem cells (NSCs). NSCs were seeded on nonaligned and aligned scaffolds and their morphology, adhesion, and differentiation capacities into the neuronal and glial pathways were studied using microscopic techniques. Significant changes in the growth and differentiation capacities of NSCs into neuronal and glial cells as a function of the fiber alignment were evidenced. These results demonstrate that PVDF scaffolds may serve as instructive scaffolds for NSC survival and differentiation, and may be valuable tools for the development of cell- and scaffold-based strategies for neural repair. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016. © 2016 Wiley Periodicals, Inc.

  9. Aligned fibers direct collective cell migration to engineer closing and nonclosing wound gaps.

    PubMed

    Sharma, Puja; Ng, Colin; Jana, Aniket; Padhi, Abinash; Szymanski, Paige; Lee, Jerry S H; Behkam, Bahareh; Nain, Amrinder S

    2017-09-15

    Cell emergence onto damaged or organized fibrous extracellular matrix (ECM) is a crucial precursor to collective cell migration in wound closure and cancer metastasis, respectively. However, there is a fundamental gap in our quantitative understanding of the role of local ECM size and arrangement in cell emergence-based migration and local gap closure. Here, using ECM-mimicking nanofibers bridging cell monolayers, we describe a method to recapitulate and quantitatively describe these in vivo behaviors over multispatial (single cell to cell sheets) and temporal (minutes to weeks) scales. On fiber arrays with large interfiber spacing, cells emerge (invade) either singularly by breaking cell-cell junctions analogous to release of a stretched rubber band (recoil), or in groups of few cells (chains), whereas on closely spaced fibers, multiple chains emerge collectively. Advancing cells on fibers form cell streams, which support suspended cell sheets (SCS) of various sizes and curvatures. SCS converge to form local gaps that close based on both the gap size and shape. We document that cell stream spacing of 375 µm and larger hinders SCS advancement, thus providing abilities to engineer closing and nonclosing gaps. Altogether we highlight the importance of studying cell-fiber interactions and matrix structural remodeling in fundamental and translational cell biology. © 2017 Sharma et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  10. Polymeric optical fiber tweezers as a tool for single cell micro manipulation and sensing

    NASA Astrophysics Data System (ADS)

    Rodrigues Ribeiro, R. S.; Soppera, O.; Guerreiro, A.; Jorge, P. A...

    2015-09-01

    In this paper a new type of polymeric fiber optic tweezers for single cell manipulation is reported. The optical trapping of a yeast cell using a polymeric micro lens fabricated by guided photo polymerization at the fiber tip is demonstrated. The 2D trapping of the yeast cells is analyzed and maximum optical forces on the pN range are calculated. The experimental results are supported by computational simulations using a FDTD method. Moreover, new insights on the potential for simultaneous sensing and optical trapping, are presented.

  11. Three-dimensional hierarchical cultivation of human skin cells on bio-adaptive hybrid fibers.

    PubMed

    Planz, Viktoria; Seif, Salem; Atchison, Jennifer S; Vukosavljevic, Branko; Sparenberg, Lisa; Kroner, Elmar; Windbergs, Maike

    2016-07-11

    The human skin comprises a complex multi-scale layered structure with hierarchical organization of different cells within the extracellular matrix (ECM). This supportive fiber-reinforced structure provides a dynamically changing microenvironment with specific topographical, mechanical and biochemical cell recognition sites to facilitate cell attachment and proliferation. Current advances in developing artificial matrices for cultivation of human cells concentrate on surface functionalizing of biocompatible materials with different biomolecules like growth factors to enhance cell attachment. However, an often neglected aspect for efficient modulation of cell-matrix interactions is posed by the mechanical characteristics of such artificial matrices. To address this issue, we fabricated biocompatible hybrid fibers simulating the complex biomechanical characteristics of native ECM in human skin. Subsequently, we analyzed interactions of such fibers with human skin cells focusing on the identification of key fiber characteristics for optimized cell-matrix interactions. We successfully identified the mediating effect of bio-adaptive elasto-plastic stiffness paired with hydrophilic surface properties as key factors for cell attachment and proliferation, thus elucidating the synergistic role of these parameters to induce cellular responses. Co-cultivation of fibroblasts and keratinocytes on such fiber mats representing the specific cells in dermis and epidermis resulted in a hierarchical organization of dermal and epidermal tissue layers. In addition, terminal differentiation of keratinocytes at the air interface was observed. These findings provide valuable new insights into cell behaviour in three-dimensional structures and cell-material interactions which can be used for rational development of bio-inspired functional materials for advanced biomedical applications.

  12. Cotton fiber tips have diverse morphologies and show evidence of apical cell wall synthesis

    PubMed Central

    Stiff , Michael R.; Haigler, Candace H.

    2016-01-01

    Cotton fibers arise through highly anisotropic expansion of a single seed epidermal cell. We obtained evidence that apical cell wall synthesis occurs through examining the tips of young elongating Gossypium hirsutum (Gh) and G. barbadense (Gb) fibers. We characterized two tip types in Gh fiber (hemisphere and tapered), each with distinct apical diameter, central vacuole location, and distribution of cell wall components. The apex of Gh hemisphere tips was enriched in homogalacturonan epitopes, including a relatively high methyl-esterified form associated with cell wall pliability. Other wall components increased behind the apex including cellulose and the α-Fuc-(1,2)-β-Gal epitope predominantly found in xyloglucan. Gb fibers had only one narrow tip type featuring characters found in each Gh tip type. Pulse-labeling of cell wall glucans indicated wall synthesis at the apex of both Gh tip types and in distal zones. Living Gh hemisphere and Gb tips ruptured preferentially at the apex upon treatment with wall degrading enzymes, consistent with newly synthesized wall at the apex. Gh tapered tips ruptured either at the apex or distantly. Overall, the results reveal diverse cotton fiber tip morphologies and support primary wall synthesis occurring at the apex and discrete distal regions of the tip. PMID:27301434

  13. The cause and consequence of fiber cell compaction in the vertebrate lens

    PubMed Central

    Bassnett, Steven; Costello, M. Joseph

    2016-01-01

    Fiber cells of the ocular lens are arranged in a series of concentric shells. New growth shells are added continuously to the lens surface and, as a consequence, the preexisting shells are buried. To focus light, the refractive index of the lens cytoplasm must exceed that of the surrounding aqueous and vitreous humors, and to that end, lens cells synthesize high concentrations of soluble proteins, the crystallins. To correct for spherical aberration, it is necessary that the crystallin concentration varies from shell-to-shell, such that cellular protein content is greatest in the center of the lens. The radial variation in protein content underlies the critical gradient index (GRIN) structure of the lens. Only the outermost shells of lens fibers contain the cellular machinery necessary for protein synthesis. It is likely, therefore, that the GRIN (which spans the synthetically inactive, organelle-free zone of the lens) does not result from increased levels of protein synthesis in the core of the lens but is instead generated through loss of volume by inner fiber cells. Because volume is lost primarily in the form of cell water, the residual proteins in the central lens fibers can be concentrated to levels of >500 mg/ml. In this short review, we describe the process of fiber cell compaction, its relationship to lens growth and GRIN formation, and offer some thoughts on the likely nature of the underlying mechanism. PMID:26992780

  14. The performance of primary human renal cells in hollow fiber bioreactors for bioartificial kidneys.

    PubMed

    Oo, Zay Yar; Deng, Rensheng; Hu, Min; Ni, Ming; Kandasamy, Karthikeyan; bin Ibrahim, Mohammed Shahrudin; Ying, Jackie Y; Zink, Daniele

    2011-12-01

    Bioartificial kidneys (BAKs) containing human primary renal proximal tubule cells (HPTCs) have been applied in clinical trials. The results were encouraging, but also showed that more research is required. Animal cells or cell lines are not suitable for clinical applications, but have been mainly used in studies on BAK development as large numbers of such cells could be easily obtained. It is difficult to predict HPTC performance based on data obtained with other cell types. To enable more extensive studies on HPTCs, we have developed a bioreactor containing single hollow fiber membranes that requires relatively small amounts of cells. Special hollow fiber membranes with the skin layer on the outer surface and consisting of polyethersulfone/polyvinylpyrrolidone were developed. The results suggested that such hollow fiber membranes were more suitable for the bioreactor unit of BAKs than membranes with an inner skin layer. An HPTC-compatible double coating was applied to the insides of the hollow fiber membranes, which sustained the formation of functional epithelia under bioreactor conditions. Nevertheless, the state of differentiation of the primary human cells remained a critical issue and should be further addressed. The bioreactor system described here will facilitate further studies on the relevant human cell type.

  15. Evaluation of various seeding techniques for culturing osteogenic cells on titanium fiber mesh.

    PubMed

    van den Dolder, Juliette; Spauwen, Paul H M; Jansen, John A

    2003-04-01

    The objective of the present study was to learn more about the effect of seeding and loading techniques on the osteogenic differentiation in vitro of rat bone marrow cells into titanium fiber mesh. This material was used as received or subjected to glow discharge treatment (RFGD). The seeding methods that were used included a so-called droplet, cell suspension (high and low cell density), and rotating plate method. Osteogenic cells were cultured for 4, 8, and 16 days into titanium fiber mesh. DNA, osteocalcin, scanning electron microscopy (SEM) analysis, and calcium measurements were used to determine cellular proliferation and differentiation. DNA analysis of the differently seeded specimens showed that proliferation proceeded faster in the first versus second run for droplet and cell suspension samples. No clear and distinct additional effect was found when RFGD treatment was used. Statistical analyses revealed that high cell density and low rotational speed resulted always in a significantly higher DNA content. Calcium measurements and osteocalcin analysis showed that using high cell densities during inoculation of the scaffolds prevented the occurrence of differences between experimental runs. SEM examination showed that for droplet and cell suspension samples cells were present at only one side of the mesh. The mesh side where the cell sheet was observed depended on the additional use of glow discharge treatment. On these materials, the cells had penetrated through the meshes and formed a cell sheet at the bottom side. When rotation was used, no cell sheet was formed and cells had invaded the meshes and were growing around the titanium fibers. On the basis of our results, we conclude that (1). titanium fiber mesh is indeed suitable to support the osteogenic expression of bone marrow cells, and (2). changing the initial cell density as well as the use of dynamic seeding methods can influence the osteogenic capacity of the scaffold.

  16. Effects of asbestos and man-made vitreous fibers on cell division in cultured human mesothelial cells in comparison to rodent cells.

    PubMed

    Pelin, K; Kivipensas, P; Linnainmaa, K

    1995-01-01

    We report the effects of chrysotile and crocidolite asbestos, and glass and rock wool fibers (man-made vitreous fibers, MMVF) on the induction of binucleate cells in vitro. The response of human mesothelial cells (target cells in fiber carcinogenesis) and rodent cells was compared. Human primary mesothelial cells, MeT-5A cells (an immortalized human mesothelial cell line), and rat liver epithelial (RLE) cells were exposed to asbestos and MMVF samples of similar size range. Milled glass wool, milled rock wool, and titanium dioxide were used as non-fibrous particle controls. All four fiber types caused statistically significant increases in the amount of binucleate cells in human primary mesothelial cells and MeT-5A cells (in the dose range 0.5-5.0 micrograms/cm2). Chrysotile and crocidolite asbestos were more effective (1.3-3.0-fold increases) than thin glass wool and thin rock wool fibers (1.3-2.2-fold increases). However, when the fiber doses were expressed as the number of fibers per culture area, the asbestos and MMVF appeared equally effective in human mesothelial cells. In RLE cells, chrysotile was the most potent inducer of binucleation (2.9-5.0-fold increases), but the response of the RLE cells to crocidolite, thin glass wool, and thin rock wool fibers was similar to the response of the human mesothelial cells. No statistically significant increases in the number of bi- or multinucleate cells were observed in human primary mesothelial cells or RLE cells exposed to the non-fibrous dusts. In MeT-5A cells exposed to 5 micrograms/cm2 of milled glass wool and milled rock wool, as well as in cultures exposed to 2 and 5 micrograms/cm2 of TiO2, significant increases were, however, observed. Our results show that rodent cells respond differently to mineral fibers than human cells. The results also add evidence to the suggested importance of disturbed cell division in fiber carcinogenesis.

  17. Effect of CNT on collagen fiber structure, stiffness assembly kinetics and stem cell differentiation.

    PubMed

    Kim, Taeyoung; Sridharan, Indumathi; Zhu, Bofan; Orgel, Joseph; Wang, Rong

    2015-04-01

    Collagen is a native one-dimensional nanomaterial. Carbon nanotube (CNT) was found to interface with biological materials and show promising applications in creating reinforced scaffolds for tissue engineering and regenerative medicine. In this study, we examined the unique role of CNT in collagen fiber structure, mechanical strength and assembly kinetics. The results imply that CNT interacts with collagen at the molecular level. It relaxes the helical coil of collagen fibrils and has the effect of flattening the fibers leading to the elongation of D-period, the characteristic banding feature of collagen fibers. The surface charge of oxidized CNT leads to enhanced local ionic strength during collagen fibrillogenesis, accounting for the slower kinetics of collagen-CNT (COL-CNT) fiber assembly and the formation of thicker fibers. Due to the rigidity of CNT, the addition of CNT increases the fiber stiffness significantly. When applied as a matrix for human decidua parietalis placental stem cells (hdpPSCs) differentiation, COL-CNT was found to support fast and efficient neural differentiation ascribed to the elongated D-period. These results highlight the superiority of CNT to modulate collagen fiber assembly at the molecular level. The study also exemplifies the use of CNT to enhance the functionality of collagen for biological and biomedical applications.

  18. Phytosterol content and the campesterol:sitosterol ratio influence cotton fiber development: role of phytosterols in cell elongation.

    PubMed

    Deng, Shasha; Wei, Ting; Tan, Kunling; Hu, Mingyu; Li, Fang; Zhai, Yunlan; Ye, Shue; Xiao, Yuehua; Hou, Lei; Pei, Yan; Luo, Ming

    2016-02-01

    Phytosterols play an important role in plant growth and development, including cell division, cell elongation, embryogenesis, cellulose biosynthesis, and cell wall formation. Cotton fiber, which undergoes synchronous cell elongation and a large amount of cellulose synthesis, is an ideal model for the study of plant cell elongation and cell wall biogenesis. The role of phytosterols in fiber growth was investigated by treating the fibers with tridemorph, a sterol biosynthetic inhibitor. The inhibition of phytosterol biosynthesis resulted in an apparent suppression of fiber elongation in vitro or in planta. The determination of phytosterol quantity indicated that sitosterol and campesterol were the major phytosterols in cotton fibers; moreover, higher concentrations of these phytosterols were observed during the period of rapid elongation of fibers. Furthermore, the decrease and increase in campesterol:sitosterol ratio was associated with the increase and decease in speed of elongation, respectively, during the elongation stage. The increase in the ratio was associated with the transition from cell elongation to secondary cell wall synthesis. In addition, a number of phytosterol biosynthetic genes were down-regulated in the short fibers of ligon lintless-1 mutant, compared to its near-isogenic wild-type TM-1. These results demonstrated that phytosterols play a crucial role in cotton fiber development, and particularly in fiber elongation.

  19. Shape-memory-actuated change in scaffold fiber alignment directs stem cell morphology.

    PubMed

    Tseng, Ling-Fang; Mather, Patrick T; Henderson, James H

    2013-11-01

    Tissue engineering scaffolds have traditionally been static physical structures poorly suited to mimicking the complex dynamic behavior of in vivo microenvironments. Here we present a thermoresponsive scaffold that can be programmed to change macroscopic shape and microscopic architecture during cell culture. The scaffold, which was prepared by electrospinning a shape memory polymer (SMP), was used to test the hypothesis that a shape-memory-actuated change in scaffold fiber alignment could be used to control the behavior of attached and viable cells. To test this hypothesis, we stretched an SMP scaffold of randomly oriented fibers and fixed the scaffold in a temporary but stable elongated shape in which fibers were aligned by the strain. Following seeding and culture of human adipose-derived stem cells on the strain-aligned scaffold, the scaffold was triggered to transition back to its initial shape and random fiber orientation via shape memory actuation using a cytocompatible temperature increase. We found that cells preferentially aligned along the fiber direction of the strain-aligned scaffold before shape memory actuation. After shape memory actuation, cells remained attached and viable but lost preferential alignment. These results demonstrate that shape-memory-actuated changes in scaffold fiber alignment can be achieved with attached and viable cells and can control cell morphological behavior. The incorporation of shape memory into cytocompatible scaffolds is anticipated to facilitate the development, delivery and functionality of tissue engineering scaffolds and the in vitro and in vivo study and application of mechanobiology. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  20. Damage to lens fiber cells causes TRPV4-dependent Src family kinase activation in the epithelium.

    PubMed

    Shahidullah, M; Mandal, A; Delamere, N A

    2015-11-01

    The bulk of the lens consists of tightly packed fiber cells. Because mature lens fibers lack mitochondria and other organelles, lens homeostasis relies on a monolayer of epithelial cells at the anterior surface. The detection of various signaling pathways in lens epithelial cells suggests they respond to stimuli that influence lens function. Focusing on Src Family Kinases (SFKs) and Transient Receptor Potential Vanilloid 4 (TRPV4), we tested whether the epithelium can sense and respond to an event that occurs in fiber mass. The pig lens was subjected to localized freeze-thaw (FT) damage to fibers at posterior pole then the lens was incubated for 1-10 min in Krebs solution at 37 °C. Transient SFK activation in the epithelium was detectable at 1 min. Using a western blot approach, the ion channel TRPV4 was detected in the epithelium but was sparse or absent in fiber cells. Even though TRPV4 expression appears low at the actual site of FT damage to the fibers, SFK activation in the epithelium was suppressed in lenses subjected to FT damage then incubated with the TRPV4 antagonist HC067047 (10 μM). Na,K-ATPase activity was examined because previous studies report changes of Na,K-ATPase activity associated with SFK activation. Na,K-ATPase activity doubled in the epithelium removed from FT-damaged lenses and the response was prevented by HC067047 or the SFK inhibitor PP2 (10 μM). Similar changes were observed in response to fiber damage caused by injection of 5 μl hyperosmotic NaCl or mannitol solution beneath the surface of the posterior pole. The findings point to a TRPV4-dependent mechanism that enables the epithelial cells to detect remote damage in the fiber mass and respond within minutes by activating SFK and increasing Na,K-ATPase activity. Because TRPV4 channels are mechanosensitive, we speculate they may be stimulated by swelling of the lens structure caused by damage to the fibers. Increased Na,K-ATPase activity gives the lens greater capacity to

  1. Spider Silk Fibers Spun from Soluble Recombinant Silk Produced in Mammalian Cells

    NASA Astrophysics Data System (ADS)

    Lazaris, Anthoula; Arcidiacono, Steven; Huang, Yue; Zhou, Jiang-Feng; Duguay, François; Chretien, Nathalie; Welsh, Elizabeth A.; Soares, Jason W.; Karatzas, Costas N.

    2002-01-01

    Spider silks are protein-based ``biopolymer'' filaments or threads secreted by specialized epithelial cells as concentrated soluble precursors of highly repetitive primary sequences. Spider dragline silk is a flexible, lightweight fiber of extraordinary strength and toughness comparable to that of synthetic high-performance fibers. We sought to ``biomimic'' the process of spider silk production by expressing in mammalian cells the dragline silk genes (ADF-3/MaSpII and MaSpI) of two spider species. We produced soluble recombinant (rc)-dragline silk proteins with molecular masses of 60 to 140 kilodaltons. We demonstrated the wet spinning of silk monofilaments spun from a concentrated aqueous solution of soluble rc-spider silk protein (ADF-3; 60 kilodaltons) under modest shear and coagulation conditions. The spun fibers were water insoluble with a fine diameter (10 to 40 micrometers) and exhibited toughness and modulus values comparable to those of native dragline silks but with lower tenacity. Dope solutions with rc-silk protein concentrations >20% and postspinning draw were necessary to achieve improved mechanical properties of the spun fibers. Fiber properties correlated with finer fiber diameter and increased birefringence.

  2. Modulation of Dendritic-Epithelial Cell Responses against Sphingomonas Paucimobilis by Dietary Fibers.

    PubMed

    Bermudez-Brito, Miriam; Faas, Marijke M; de Vos, Paul

    2016-07-25

    Non-fermenting Gram-negative bacilli, such as Sphingomonas paucimobilis (S.paucimobilis), are among the most widespread causes of nosocomial infections. Up to now, no definitive guidelines exist for antimicrobial therapy for S. paucimobilis infections. As we have shown that some dietary fibers exhibit pronounced immune-regulatory properties, we hypothesized that specific immune active dietary fibers might modulate the responses against S. paucimobilis. We studied the immunomodulatory effects of dietary fibers against S. paucimobilis on cytokine release and maturation of human dendritic cells (DCs) in co-cultures of DCs and intestinal epithelial cells (IECs). S. paucimobilis infection resulted in increased release of pro-inflammatory cytokines and chemokines by DCs/IECs; these effects were strongly attenuated by specific dietary fibers. Chicory inulin, sugar beet pectin, and both starches had the strongest regulatory effects. IL-12 and TNF-α were drastically diminished upon exposure to chicory inulin and sugar beet pectin, or both starches. High-maize 260, was more effective in the reduction of chemokine release than the others fibers tested. In summary, chicory inulin, sugar beet pectin, High-maize 260, and Novelose 330 attenuate S. paucimobilis-induced cytokines. These results demonstrate that dietary fibers with a specific chemical composition can be used to manage immune responses against pathogens such as S. paucimobilis.

  3. Modulation of Dendritic-Epithelial Cell Responses against Sphingomonas Paucimobilis by Dietary Fibers

    PubMed Central

    Bermudez-Brito, Miriam; Faas, Marijke M; de Vos, Paul

    2016-01-01

    Non-fermenting Gram-negative bacilli, such as Sphingomonas paucimobilis (S.paucimobilis), are among the most widespread causes of nosocomial infections. Up to now, no definitive guidelines exist for antimicrobial therapy for S. paucimobilis infections. As we have shown that some dietary fibers exhibit pronounced immune-regulatory properties, we hypothesized that specific immune active dietary fibers might modulate the responses against S. paucimobilis. We studied the immunomodulatory effects of dietary fibers against S. paucimobilis on cytokine release and maturation of human dendritic cells (DCs) in co-cultures of DCs and intestinal epithelial cells (IECs). S. paucimobilis infection resulted in increased release of pro-inflammatory cytokines and chemokines by DCs/IECs; these effects were strongly attenuated by specific dietary fibers. Chicory inulin, sugar beet pectin, and both starches had the strongest regulatory effects. IL-12 and TNF-α were drastically diminished upon exposure to chicory inulin and sugar beet pectin, or both starches. High-maize 260, was more effective in the reduction of chemokine release than the others fibers tested. In summary, chicory inulin, sugar beet pectin, High-maize 260, and Novelose 330 attenuate S. paucimobilis-induced cytokines. These results demonstrate that dietary fibers with a specific chemical composition can be used to manage immune responses against pathogens such as S. paucimobilis. PMID:27452116

  4. Complexity and health functionality of plant cell wall fibers from fruits and vegetables.

    PubMed

    Padayachee, A; Day, L; Howell, K; Gidley, M J

    2017-01-02

    The prevalence of lifestyle-related diseases is increasing in developing countries with the causes for death starting to follow the same pattern in the developed world. Lifestyle factors including inadequate dietary intake of fruits and vegetables and over consumption of nutrient-poor processed foods, are considered to be major causal risk factors associated with increased susceptibility to developing certain diseases (Alldrick, 1998 ; Kiani, 2007 ). Recent epidemiological evidence confirms a strong association between dietary fiber and reduced all-cause mortality risk, as well as a risk reduction for a number of non-communicable diseases (Chuang et al., 2012 ). The relationship between dietary fiber and mortality has been described as "convincing observations that call for mechanistic investigations" (Landberg, 2012 ). In particular, the health protective roles played by dietary fibers of different origin are not well understood. Whilst Hippocrates was the earliest known physician to study the health benefits of fiber derived from grains (Burkitt, 1987 ), the functionality of fruit and vegetable fiber, especially in association with other compounds such as polyphenols and carotenoids, is an area of more recent interest. Hence the objective of this review is to assess the complexity and health-related functional role of plant cell wall (PCW) fibers from fruits and vegetables with a particular emphasis on interactions between cell walls and phytonutrients.

  5. Unique and analogous functions of aquaporin O for fiber cell architecture and ocular lens transparency

    SciTech Connect

    Kumari, S.S.; Eswaramoorthy, S.; Mathias, R. T.; Varadaraj, K.

    2011-09-01

    Aquaporin (AQP) 1 and AQP0 water channels are expressed in lens epithelial and fiber cells, respectively, facilitating fluid circulation for nourishing the avascular lens to maintain transparency. Even though AQP0 water permeability is 40-fold less than AQP1, AQP0 is selectively expressed in the fibers. Delimited AQP0 fiber expression is attributed to a unique structural role as an adhesion protein. To validate this notion, we determined if wild type (WT) lens ultrastructure and fibercell adhesion are different in AQP0{sup -/-}, and TgAQP1{sup +/+}/AQP0{sup -/-} mice that transgenically express AQP1 (TgAQP1) in fibercells without AQP0 (AQP0{sup -/-}). In WT, lenses were transparent with 'Y' sutures. Fibers contained opposite end curvature, lateral interdigitations, hexagonal shape, and were arranged as concentric growth shells. AQP0{sup -/-}lenses were cataractous, lacked 'Y' sutures, ordered packing and well-defined lateral interdigitations. TgAQP1{sup +/+}/AQP0{sup -/-} lenses showed improvement in transparency and lateral interdigitations in the outer cortex while inner cortex and nuclear fibers were severely disintegrated. Transmission electron micrographs exhibited tightly packed fibercells in WT whereas AQP0{sup -/-} and TgAQP1{sup +/+}/AQP0{sup -/-}lenses had wide extracellular spaces. Fibers were easily separable by teasing in AQP0{sup -/-} and TgAQP1{sup +/+}/AQP0{sup -/-}lenses compared to WT. Our data suggest that the increased water permeability through AQP1 does not compensate for loss of AQP0 expression in TgAQP1{sup +/+}/AQP0{sup -/-} mice. Fibercell AQP0 expression is required to maintain their organization, which is a requisite for lenstransparency. AQP0 appears necessary for cell-to-cell adhesion and thereby to minimize light scattering since in the AQP0{sup -/-} and TgAQP1{sup +/+}/AQP0{sup -/-} lenses, fiber cell disorganization was evident.

  6. Tropomodulin1 is required for membrane skeleton organization and hexagonal geometry of fiber cells in the mouse lens

    PubMed Central

    Nowak, Roberta B.; Fischer, Robert S.; Zoltoski, Rebecca K.; Kuszak, Jerome R.

    2009-01-01

    Hexagonal packing geometry is a hallmark of close-packed epithelial cells in metazoans. Here, we used fiber cells of the vertebrate eye lens as a model system to determine how the membrane skeleton controls hexagonal packing of post-mitotic cells. The membrane skeleton consists of spectrin tetramers linked to actin filaments (F-actin), which are capped by tropomodulin1 (Tmod1) and stabilized by tropomyosin (TM). In mouse lenses lacking Tmod1, initial fiber cell morphogenesis is normal, but fiber cell hexagonal shapes and packing geometry are not maintained as fiber cells mature. Absence of Tmod1 leads to decreased γTM levels, loss of F-actin from membranes, and disrupted distribution of β2-spectrin along fiber cell membranes. Regular interlocking membrane protrusions on fiber cells are replaced by irregularly spaced and misshapen protrusions. We conclude that Tmod1 and γTM regulation of F-actin stability on fiber cell membranes is critical for the long-range connectivity of the spectrin–actin network, which functions to maintain regular fiber cell hexagonal morphology and packing geometry. PMID:19752024

  7. In Situ Liquid Cell Observations of Asbestos Fiber Diffusion in Water

    PubMed Central

    Wu, Lei; Ortiz, Carlos; Xu, Ye; Willenbring, Jane; Jerolmack, Douglas

    2016-01-01

    We present real-time observations of the diffusion of individual asbestos fibers in water. We first scaled up a technique for fluorescent tagging and imaging of chrysotile asbestos fibers and prepared samples with a distribution of fiber lengths ranging from 1 to 20 μm. Experiments were then conducted by placing a 20, 100, or 150 ppm solution of these fibers in a liquid cell mounted on a spinning-disk confocal microscope. Using automated elliptical-particle detection methods, we determined the translation and rotation and two-dimensional (2D) trajectories of thousands of diffusing chrysotile fibers. We find that fiber diffusion is size-dependent and in reasonable agreement with theoretical predictions for the Brownian motion of rods. This agreement is remarkable given that experiments involved non-idealized particles at environmentally relevant concentrations in a confined cell, in which particle–particle and particle–wall interactions might be expected to cause deviations from theory. Experiments also confirmed that highly elongated chrysotile fibers exhibit anisotropic diffusion at short time scales, a predicted effect that may have consequences for aggregate formation and transport of asbestos in confined spaces. The examined fibers vary greatly in their lengths and were prepared from natural chrysotile. Our findings thus indicate that the diffusion rates of a wide range of natural colloidal particles can be predicted from theory, so long as the particle aspect ratio is properly taken into account. This is an important first step for understanding aggregate formation and transport of non-spherical contaminant particles, in the environment and in vivo. PMID:26461183

  8. In Situ Liquid Cell Observations of Asbestos Fiber Diffusion in Water.

    PubMed

    Wu, Lei; Ortiz, Carlos; Xu, Ye; Willenbring, Jane; Jerolmack, Douglas

    2015-11-17

    We present real-time observations of the diffusion of individual asbestos fibers in water. We first scaled up a technique for fluorescent tagging and imaging of chrysotile asbestos fibers and prepared samples with a distribution of fiber lengths ranging from 1 to 20 μm. Experiments were then conducted by placing a 20, 100, or 150 ppm solution of these fibers in a liquid cell mounted on a spinning-disk confocal microscope. Using automated elliptical-particle detection methods, we determined the translation and rotation and two-dimensional (2D) trajectories of thousands of diffusing chrysotile fibers. We find that fiber diffusion is size-dependent and in reasonable agreement with theoretical predictions for the Brownian motion of rods. This agreement is remarkable given that experiments involved non-idealized particles at environmentally relevant concentrations in a confined cell, in which particle-particle and particle-wall interactions might be expected to cause deviations from theory. Experiments also confirmed that highly elongated chrysotile fibers exhibit anisotropic diffusion at short time scales, a predicted effect that may have consequences for aggregate formation and transport of asbestos in confined spaces. The examined fibers vary greatly in their lengths and were prepared from natural chrysotile. Our findings thus indicate that the diffusion rates of a wide range of natural colloidal particles can be predicted from theory, so long as the particle aspect ratio is properly taken into account. This is an important first step for understanding aggregate formation and transport of non-spherical contaminant particles, in the environment and in vivo.

  9. Interactions between lens epithelial and fiber cells reveal an intrinsic self-assembly mechanism

    PubMed Central

    Dawes, LJ; Sugiyama, Y; Lovicu, FJ; Harris, C; Shelley, EJ; McAvoy, JW

    2013-01-01

    How tissues and organs develop and maintain their characteristic three-dimensional cellular architecture is often a poorly understood part of their developmental program; yet, as is clearly the case for the eye lens, precise regulation of these features can be critical for function. During lens morphogenesis cells become organized into a polarized, spheroidal structure with a monolayer of epithelial cells overlying the apical tips of elongated fiber cells. Epithelial cells proliferate and progeny that shift below the lens equator differentiate into new fibers that are progressively added to the fiber mass. It is now known that FGF induces epithelial to fiber differentiation; however, it is not fully understood how these two forms of cells assemble into their characteristic polarized arrangement. Here we show that in FGF-treated epithelial explants, elongating fibers become polarized/oriented towards islands of epithelial cells and mimic their polarized arrangement in vivo. Epithelial explants secrete Wnt5 into the culture medium and we show that Wnt5 can promote directed behaviour of lens cells. We also show that these explants replicate aspects of the Notch/Jagged signaling activity that has been shown to regulate proliferation of epithelial cells in vivo. Thus, our in vitro study identifies a novel mechanism, intrinsic to the two forms of lens cells, that facilitates self-assembly into the polarized arrangement characteristic of the lens in vivo. In this way the lens, with its relatively simple cellular composition, serves as a useful model to highlight the importance of such intrinsic self-assembly mechanisms in tissue developmental and regenerative processes. PMID:24211762

  10. Cell flow analysis with a two-photon fluorescence fiber probe

    NASA Astrophysics Data System (ADS)

    Chang, Yu-Chung; Ye, Jing Yong; Thomas, Thommey P.; Baker, James R., Jr.; Norris, Theodore B.

    2010-11-01

    We report the use of a sensitive double-clad fiber (DCF) probe for in situ cell flow velocity measurements and cell analysis by means of two-photon excited fluorescence correlation spectroscopy (FCS). We have demonstrated the feasibility to use this fiber probe for in vivo two-photon flow cytometry previously. However, because of the viscosity of blood and the non-uniform flow nature in vivo, it is problematic to use the detected cell numbers to estimate the sampled blood volume. To precisely calibrate the sampled blood volume, it is necessary to conduct real time flow velocity measurement. We propose to use FCS technique to measure the flow velocity. The ability to measure the flow velocities of labeled cells in whole blood has been demonstrated. Our two-photon fluorescence fiber probe has the ability to monitor multiple fluorescent biomarkers simultaneously. We demonstrate that we can distinguish differently labeled cells by their distinct features on the correlation curves. The ability to conduct in situ cell flow analysis using the fiber probe may be useful in disease diagnosis or further comprehension of the circulation system.

  11. Hollow fiber membrane diffusive permeability regulates encapsulated cell line biomass, proliferation, and small molecule release.

    PubMed

    Broadhead, Kelly W; Biran, Roy; Tresco, Patrick A

    2002-12-01

    Using histological and HPLC methods, we examined the influence of hollow fiber membrane transport properties on encapsulated PC12 cell biomass, proliferation and the release of dopamine over 4 weeks in culture. Our data indicated that encapsulated cell biomass, the number of proliferating cells, and the quantity of dopamine released increased as a function of increasing hollow fiber encapsulation membrane diffusive permeability. Overall the percentage of viable cells and the biomass architecture, however, was not significantly affected by differences in membrane transport. When compared to membrane sieving properties, membrane diffusive transport and membrane hydraulic permeability were better indicators of biomass size, proliferating cell number, and dopamine release from encapsulated cells. Studies examining the sustained release of DA from membranes of differing permeability suggest that membrane diffusive permeability can be used to regulate the quantity of small molecules released per unit time at steady state, and should be considered when dosing is an important determinant of implant efficacy. Copyright 2002 Elsevier Science Ltd.

  12. Microfluidic cell counter with embedded optical fibers fabricated by femtosecond laser ablation and anodic bonding.

    PubMed

    Schafer, Dawn; Gibson, Emily A; Salim, Evan A; Palmer, Amy E; Jimenez, Ralph; Squier, Jeff

    2009-04-13

    A simple fabrication technique to create all silicon/glass microfluidic devices is demonstrated using femtosecond laser ablation and anodic bonding. In a first application, we constructed a cell counting device based on small angle light scattering. The counter featured embedded optical fibers for multiangle excitation and detection of scattered light and/or fluorescence. The performance of the microfluidic cell counter was benchmarked against a commercial fluorescence-activated cell sorter.

  13. Microfluidic cell counter with embedded optical fibers fabricated by femtosecond laser ablation and anodic bonding

    PubMed Central

    Schafer, Dawn; Gibson, Emily A.; Salim, Evan A.; Palmer, Amy E.; Jimenez, Ralph; Squier, Jeff

    2011-01-01

    A simple fabrication technique to create all silicon/glass microfluidic devices is demonstrated using femtosecond laser ablation and anodic bonding. In a first application, we constructed a cell counting device based on small angle light scattering. The counter featured embedded optical fibers for multiangle excitation and detection of scattered light and/or fluorescence. The performance of the microfluidic cell counter was benchmarked against a commercial fluorescence-activated cell sorter. PMID:19365429

  14. Isolation of satellite cells from single muscle fibers from young, aged, or dystrophic muscles.

    PubMed

    Di Foggia, Valentina; Robson, Lesley

    2012-01-01

    Skeletal muscle contains an identified resident stem cell population called the satellite cells. This cell is responsible for the majority of the postnatal growth and regenerative potential of skeletal muscle. Other cells do contribute to skeletal muscle regeneration and in cultures of minced whole muscle these cells are cultured along with the satellite cells and it is impossible to dissect out their contribution compared to the satellite cells. Therefore, a method to culture pure satellite cells has been developed to study the signaling pathways that control their proliferation and differentiation. In our studies into the role of the resident myogenic stem cells in regeneration, myopathic conditions, and aging, we have optimized the established techniques that already exist to isolate pure satellite cell cultures from single muscle fibers. We have successfully isolated satellite cells from young adults through to 24-month-old muscles and obtained populations of cells that we are studying for the signaling events that regulate their proliferative potential.

  15. Fiber-optic control and thermometry of single-cell thermosensation logic.

    PubMed

    Fedotov, I V; Safronov, N A; Ermakova, Yu G; Matlashov, M E; Sidorov-Biryukov, D A; Fedotov, A B; Belousov, V V; Zheltikov, A M

    2015-11-13

    Thermal activation of transient receptor potential (TRP) cation channels is one of the most striking examples of temperature-controlled processes in cell biology. As the evidence indicating the fundamental role of such processes in thermosensation builds at a fast pace, adequately accurate tools that would allow heat receptor logic behind thermosensation to be examined on a single-cell level are in great demand. Here, we demonstrate a specifically designed fiber-optic probe that enables thermal activation with simultaneous online thermometry of individual cells expressing genetically encoded TRP channels. This probe integrates a fiber-optic tract for the delivery of laser light with a two-wire microwave transmission line. A diamond microcrystal fixed on the fiber tip is heated by laser radiation transmitted through the fiber, providing a local heating of a cell culture, enabling a well-controlled TRP-assisted thermal activation of cells. Online local temperature measurements are performed by using the temperature-dependent frequency shift of optically detected magnetic resonance, induced by coupling the microwave field, delivered by the microwave transmission line, to nitrogen--vacancy centers in the diamond microcrystal. Activation of TRP channels is verified by using genetically encoded fluorescence indicators, visualizing an increase in the calcium flow through activated TRP channels.

  16. Fiber-optic control and thermometry of single-cell thermosensation logic

    PubMed Central

    Fedotov, I.V.; Safronov, N.A.; Ermakova, Yu.G.; Matlashov, M.E.; Sidorov-Biryukov, D.A.; Fedotov, A.B.; Belousov, V.V.; Zheltikov, A.M.

    2015-01-01

    Thermal activation of transient receptor potential (TRP) cation channels is one of the most striking examples of temperature-controlled processes in cell biology. As the evidence indicating the fundamental role of such processes in thermosensation builds at a fast pace, adequately accurate tools that would allow heat receptor logic behind thermosensation to be examined on a single-cell level are in great demand. Here, we demonstrate a specifically designed fiber-optic probe that enables thermal activation with simultaneous online thermometry of individual cells expressing genetically encoded TRP channels. This probe integrates a fiber-optic tract for the delivery of laser light with a two-wire microwave transmission line. A diamond microcrystal fixed on the fiber tip is heated by laser radiation transmitted through the fiber, providing a local heating of a cell culture, enabling a well-controlled TRP-assisted thermal activation of cells. Online local temperature measurements are performed by using the temperature-dependent frequency shift of optically detected magnetic resonance, induced by coupling the microwave field, delivered by the microwave transmission line, to nitrogen—vacancy centers in the diamond microcrystal. Activation of TRP channels is verified by using genetically encoded fluorescence indicators, visualizing an increase in the calcium flow through activated TRP channels. PMID:26563494

  17. Vitronectin adsorption to chrysotile asbestos increases fiber phagocytosis and toxicity for mesothelial cells.

    PubMed

    Wu, J; Liu, W; Koenig, K; Idell, S; Broaddus, V C

    2000-11-01

    Biological modification of asbestos fibers can alter their interaction with target cells. We have shown that vitronectin (VN), a major adhesive protein in serum, adsorbs to crocidolite asbestos and increases fiber phagocytosis by mesothelial cells via integrins. Because chrysotile asbestos differs significantly from crocidolite in charge and shape, we asked whether VN would also adsorb to chrysotile asbestos and increase its toxicity for mesothelial cells. We found that VN, either from purified solutions or from serum, adsorbed to chrysotile but at a lower amount per surface area than to crocidolite. Nevertheless, VN coating increased the phagocytosis of chrysotile as well as of crocidolite asbestos. VN coating of both chrysotile and crocidolite, but not of glass beads, increased intracellular oxidation and apoptosis of mesothelial cells. The additional apoptosis could be blocked by integrin-ligand blockade with arginine-glycine-aspartic acid peptides, confirming a role for integrins in the fiber-induced toxicity. We conclude that VN increases the phagocytosis of chrysotile as well as of crocidolite asbestos and that phagocytosis is important in fiber-induced toxicity for mesothelial cells.

  18. Fiber-optic control and thermometry of single-cell thermosensation logic

    NASA Astrophysics Data System (ADS)

    Fedotov, I. V.; Safronov, N. A.; Ermakova, Yu. G.; Matlashov, M. E.; Sidorov-Biryukov, D. A.; Fedotov, A. B.; Belousov, V. V.; Zheltikov, A. M.

    2015-11-01

    Thermal activation of transient receptor potential (TRP) cation channels is one of the most striking examples of temperature-controlled processes in cell biology. As the evidence indicating the fundamental role of such processes in thermosensation builds at a fast pace, adequately accurate tools that would allow heat receptor logic behind thermosensation to be examined on a single-cell level are in great demand. Here, we demonstrate a specifically designed fiber-optic probe that enables thermal activation with simultaneous online thermometry of individual cells expressing genetically encoded TRP channels. This probe integrates a fiber-optic tract for the delivery of laser light with a two-wire microwave transmission line. A diamond microcrystal fixed on the fiber tip is heated by laser radiation transmitted through the fiber, providing a local heating of a cell culture, enabling a well-controlled TRP-assisted thermal activation of cells. Online local temperature measurements are performed by using the temperature-dependent frequency shift of optically detected magnetic resonance, induced by coupling the microwave field, delivered by the microwave transmission line, to nitrogen—vacancy centers in the diamond microcrystal. Activation of TRP channels is verified by using genetically encoded fluorescence indicators, visualizing an increase in the calcium flow through activated TRP channels.

  19. Dual membrane hollow fiber fuel cell and method of operating same

    NASA Technical Reports Server (NTRS)

    Ingham, J. D.; Lawson, D. D. (Inventor)

    1978-01-01

    A gaseous fuel cell is described which includes a pair of electrodes formed by open-ended, ion-exchange hollow fibers, each having a layer of metal catalyst deposited on the inner surface and large surface area current collectors such as braided metal mesh in contact with the metal catalyst layer. A fuel cell results when the electrodes are immersed in electrolytes and electrically connected. As hydrogen and oxygen flow through the bore of the fibers, oxidation and reduction reactions develop an electrical potential. Since the hollow fiber configuration provides large electrode area per unit volume and intimate contact between fuel and oxidizer at the interface, and due to the low internal resistance of the electrolyte, high power densities can be obtained.

  20. Ultraviolet spectroscopic breath analysis using hollow-optical fiber as gas cell

    NASA Astrophysics Data System (ADS)

    Iwata, T.; Katagiri, T.; Matsuura, Y.

    2017-02-01

    For breath analysis on ultraviolet absorption spectroscopy, an analysis system using a hollow optical fiber as gas cell is developed. The hollow optical fiber functions as a long path and extremely small volume gas cell. Firstly, the measurement sensitivity of the system is evaluated by using NO gas as a gas sample. The result shows that NO gas with 50 ppb concentration is measured by using a system with a laser-driven, high intensity light source and a 3-meter long, aluminum-coated hollow optical fiber. Then an absorption spectrum of breath sample is measured in the wavelength region of around 200-300 nm and from the spectrum, it is found that the main absorbing components in breath were H2O, isoprene, and O3 converted from O2 by radiation of ultraviolet light. Then the concentration of isoprene in breath is estimated by using multiple linear regression analysis.

  1. Somatostatin-immunoreactive nerve cell bodies and fibers in the medulla oblongata et spinalis.

    PubMed

    Forssmann, W G; Burnweit, C; Shehab, T; Triepel, J

    1979-10-01

    Complete serial sectioning of the medulla oblongata in monkey, cat, guinea pig, and japanese dancing mouse and incubation for somatostatin-immunoreaction was carried out. Numerous regions of the medulla oblongata such as the nucleus reticularis gigantocellularis, nucleus cuneatus et gracillis, nucleus raphe magnus, nucleus tractus solitarius, nucleus vestibularis, and parts of the oliva contain dense networks of somatostatin-immunoreactive nerve fibers. Cell bodies were seen in the nucleus reticularis medullae oblongatae. In the spinal cord the sections from each segment were analyzed, showing the highest concentrations of somatostatinergic fibers in the substantia gelantinosa of the columna dorsalis. Cell bodies were seen in the zona intermedia centralis, especially in the upper cervical segments. Many positive fibers were also seen in the entire zona intermedia and the columna ventralis. Especially prominent was the immunoreactivity in the zona intermediolateralis of the thoracic segments and the columna ventralis of the lower lumbar and sacral segments.

  2. Extracellular Recordings of Patterned Human Pluripotent Stem Cell-Derived Cardiomyocytes on Aligned Fibers

    PubMed Central

    Minami, Itsunari; Yu, Leqian; Nakajima, Minako; Qiao, Jing; Shimono, Ken; Nakatsuji, Norio; Kotera, Hitetoshi; Chen, Yong

    2016-01-01

    Human induced pluripotent stem cell (hiPSC) derived cardiomyocytes (CMs) hold high potential for use in drug assessment and myocardial regeneration. To create tissue-like constructs of CMs for extracellular monitoring, we placed aligned fibers (AFs) on the surface of a microelectrode array and then seeded hiPSC-CMs for subsequent monitoring for 14 days. As expected, the CMs organized into anisotropic and matured tissue and the extracellular recordings showed reduced premature beating higher signal amplitude and a higher probability of T-wave detection as compared to the culture without fibers. The CMs on the aligned fibers samples also exhibited anisotropic propagation of the field potential. These results therefore suggest that the hiPSC-CMs cultured on AFs can be used more reliably for cell based assays. PMID:27446217

  3. Dietary fiber intake and risk of renal cell carcinoma: evidence from a meta-analysis.

    PubMed

    Huang, Tian-bao; Ding, Pei-pei; Chen, Jian-feng; Yan, Yang; Zhang, Long; Liu, Huan; Liu, Peng-cheng; Che, Jian-ping; Zheng, Jun-hua; Yao, Xu-dong

    2014-08-01

    The aim of this study was to investigate the possible relationships between dietary fiber intake and risk of renal cell carcinoma (RCC). Electronic databases including MEDLINE, EMBASE and Web of Science were searched to find eligible studies. Random-effects relative risk (RR) and its corresponding 95 % confidence interval (CI) were used. Besides, random-effects dose-response analyses were also performed to clarify the dose-response relations. Finally, publication bias was assessed by Egger's test and Begg's test. All p values were two tailed. Seven studies, including two cohort studies and five case-control studies, were eligible and included in this meta-analysis. Overall analysis in highest versus lowest level revealed that total dietary fiber intake was associated with reduced RCC risk (RR 0.84, 95 % CI 0.74-0.96). In addition, pooled estimated data showed that risk of RCC was significantly associated with vegetable and legume fiber intake (RR 0.70, RR 0.80, respectively), but not with fruit and cereal fiber intake (RR 0.92, RR 1.04, respectively). However, in dose-response analysis, no significant association was reported. Finally, no publication bias was detected by Egger's or Begg's test. The dietary fiber intake, especially vegetable and legume fiber, may be associated with reduced RCC risk. Considering the limitations of the included studies, more well-designed prospective studies will be needed to confirm our findings.

  4. Supraependymal cells and fibers during the early stages of chick rhombencephalic development.

    PubMed

    Ojeda, J L; Piedra, S

    1998-09-01

    Supraependymal cellular elements are a constant feature in the adult cerebroventricular system. However, there has been no analysis of their distribution and morphology during the embryonic stages of the chick brain. The ultrastructural features of the rhombencephalic luminal surface of chick embryos ranging from stage 10 to 22 were studied with both scanning and transmission electron microscopy. In addition, immunocytochemistry and confocal laser microscopy were used to examine the presence of 68 kD neurofilaments in supraependymal elements. The ultrastructural observations revealed significant morphological differences in the apical cell surface between the cells at rhombomere boundaries and those in the rhombomere bodies. These differences support the idea that the boundary and the body of rhombomeres contain two morphologically distinct cell types. Supraependymal (SE) cells and SE fibers were present in the rhombencephalon of all embryos studied from stage 12 to 22. The cells were bipolar spindle-shaped. The SE fibers showed a characteristic spatial pattern within the rhombencephalon, following a straight course parallel to the rhombomere boundaries. The SE fibers showed varicosities and their endings contained small vesicles. Both SE cells and SE fibers were positive for 68 kD neurofilaments. Their morphology and reactivity for neurofilaments indicate a neuronal function. The constant presence of SE cells and SE fibers on the surface of the developing rhombencephalon, their special pattern and close relationship with the neural tube fluid (NTF) suggest that these supraependymal elements may be involved in a neuronal signalling pathway between different parts of the same rhombomere and also in chemical communication and integration within the ventricular system, linking distant parts of the developing central nervous system by means of NTF.

  5. Air Entrainment in a Liquid Cell due to Fiber Drawing

    NASA Astrophysics Data System (ADS)

    Simpkins, P. G.; Kuck, V. J.

    1997-11-01

    Preliminary observations of air entrainment into a liquid bath of viscous Newtonian fluid are described. The motion generated by an optical fiber moving vertically through the bath gives rise to a free surface that is cusp-like. Photomicrographs of the contact region, however, illustrate that the free surface profile becomes conical with a small included angle that is draw speed dependent. There is some evidence to suggest that tip-streaming ( Taylor, G. I. 1934 The Formation of Emulsions in Definable Fields of Flow. Proc. Roy. Soc. Lond. A146, 501-523.) footnote Sherwood, J. D. 1984 Tip Streaming from Slender Drops in a Nonlinear Extensional Flow. J. Fluid Mech. 144, 281-295. filaments of air emanate from the contact zone to give rise to minute ( 10mm) bubbles via Rayleigh-Taylor instability. Continuous operation after the onset of tip-streaming results in the creation of larger bubbles from the small ones via coalescence during recirculation in the bath. Eventually the occurrence of very large bubbles can lead to break out and the absence of any coating on the fiber.

  6. A suspended carbon fiber culture to model myelination by human Schwann cells.

    PubMed

    Merolli, Antonio; Mao, Yong; Kohn, Joachim

    2017-04-01

    Understanding of myelination/remyelination process is essential to guide tissue engineering for nerve regeneration. In vitro models currently used are limited to cell population studies and cannot easily identify individual cell contribution to the process. We established a novel model to study the contribution of human Schwann cells to the myelination process. The model avoids the presence of neurons in culture; Schwann cells respond solely to the biophysical properties of an artificial axon. The model uses a single carbon fiber suspended in culture media far from the floor of the well. The fiber provides an elongated structure of defined diameter with 360-degree of surface available for human Schwann cells to wrap around. This model enabled us to spatially and temporally track the myelination by individual Schwann cells along the fiber. We observed cell attachment, elongation and wrapping over a period of 9 days. Cells remained alive and expressed Myelin Basic Protein and Myelin Associated Glycoprotein as expected. Natural and artificial molecules, and external physical factors (e.g., p atterned electrical impulses), may be tested with this model as possible regulators of myelination.

  7. Interactions between endothelial cells and electrospun methacrylic terpolymer fibers for engineered vascular replacements.

    PubMed

    Veleva, A N; Heath, D E; Johnson, J K; Nam, J; Patterson, C; Lannutti, J J; Cooper, S L

    2009-12-15

    A compliant terpolymer made of hexylmethacrylate (HMA), methylmethacrylate (MMA), and methacrylic acid (MAA) intended for use in small diameter vascular graft applications has been developed. The mechanical properties and in vitro biostability of this terpolymer have been previously characterized. The goal of this investigation was to examine the interactions between endothelial cells and the new terpolymer and to evaluate endothelial cell function. Electrospinning was used to produce both oriented and random terpolymer fiber scaffolds. Smooth solution cast films and tissue culture polystyrene were used as negative and positive controls, respectively. Human blood outgrowth endothelial cells and human umbilical vein endothelial cells were incubated with the test and control samples and characterized with respect to initial cell attachment, proliferation, viability, and maintenance of the endothelial cell phenotype. It was found that the terpolymer is cytocompatible allowing endothelial cell growth, with random fibers being more effective in promoting enhanced cellular activities than oriented fibers. In addition, endothelial cells cultured on these substrates appeared to maintain their phenotype. The results from this study demonstrate that electrospun HMA:MMA:MAA terpolymer has the potential to be used successfully in fabricating small diameter blood vessel replacements.

  8. Air-bubbling, hollow-fiber reactor with cell bleeding and cross-flow filtration.

    PubMed

    Nishii, K; Sode, K; Karube, I

    1990-05-01

    Continuous asymmetric reduction of dyhydrooxoisophorone (DOIP) to 4-hydroxy-2,2,6-trimethylcyclo-hexanone (4-HTMCH) was achieved by a thermophilic bacterium Bacillus stearothermophilus NK86-0151. Three reactors were used: an air-bubbling hollow-fiber reactor with cell bleeding and cross-flow filtration, an air-lift reactor, and a CSTR with PAA immobilized cells. The maximum cell concentration of 11.1 g dry wt L(-1) was obtained in an air-bubbling hollow-fiber reactor, while in the other reactors the cell densities were between 3.5 and 4.1 g dry wt L(-1) The optimum bleed ratio was 0.1 at the dilution rate 0.3 h(-1) in the hollow-fiber reactor. The highest viable cell concentration was maintained in the dilution range of 0.4-0.7 h(-1) by a combination of proper cell bleeding and cross-flow filtration. The maximum volumetric productivity of 4-HTMCH reached 826 mg L(-1) h(-1) at the dilution rate 0.54 h(-1). This value was 4 and 2 times higher than those in the air-lift reactor and CSTR, respectively. The increasing viable cell concentration increased the volumetric productivity of 4-HTMCH. A cell free product solution was continuously obtained by cross-flow filtration.

  9. Fermentable dietary fiber potentiates the localization of immune cells in the rat large intestinal crypts.

    PubMed

    Ishizuka, Satoshi; Tanaka, Seiji; Xu, Hong; Hara, Hiroshi

    2004-10-01

    Intestinal crypts are composed of a well-defined hierarchy of epithelial cells, and proliferating epithelial cells reside close to the bottom of the crypts-even in the large intestine. We investigated whether CD8(+)and CD4(+)intraepithelial lymphocytes (IELs) and CD161(+) natural killer (NK) cells localized in proliferating or differentiated epithelial region of cecum and colon. Both proliferating epithelial layer cells and the immune cells along the longitudinal crypt axis of the large intestine were measured histochemically. Dietary intervention revealed that the physiological localization of the immune cells in the longitudinal crypt axis depended on the immune cell type. CD8(+) IELs were preferentially located among differentiated epithelial cells. In contrast, CD161(+) NK cells were located adjacent to the epithelial cells at the bottom of crypt. Cecal crypts contained significantly larger numbers of CD8(+) IELs than did colonic crypts. However, there was only a minor population of CD4(+) IEL in the cecal and colonic epithelia. Some dietary fibers increased the densities of CD8(+) IELs and CD161(+) NK cells in the cecum, with the magnitude of response varying among the types of fiber. There was a significant relationship between SCFA and the localization of immune cells, especially CD8(+) IEL and CD161(+) NK cells, which are considered to be involved in the maintenance of epithelial homeostasis.

  10. Proteomic Analysis of Lipid Raft-Like Detergent-Resistant Membranes of Lens Fiber Cells

    PubMed Central

    Wang, Zhen; Schey, Kevin L.

    2015-01-01

    Purpose Plasma membranes of lens fiber cells have high levels of long-chain saturated fatty acids, cholesterol, and sphingolipids—key components of lipid rafts. Thus, lipid rafts are expected to constitute a significant portion of fiber cell membranes and play important roles in lens biology. The purpose of this study was to characterize the lens lipid raft proteome. Methods Quantitative proteomics, both label-free and iTRAQ methods, were used to characterize lens fiber cell lipid raft proteins. Detergent-resistant, lipid raft membrane (DRM) fractions were isolated by sucrose gradient centrifugation. To confirm protein localization to lipid rafts, protein sensitivity to cholesterol removal by methyl-β-cyclodextrin was quantified by iTRAQ analysis. Results A total of 506 proteins were identified in raft-like detergent-resistant membranes. Proteins identified support important functions of raft domains in fiber cells, including trafficking, signal transduction, and cytoskeletal organization. In cholesterol-sensitivity studies, 200 proteins were quantified and 71 proteins were strongly affected by cholesterol removal. Lipid raft markers flotillin-1 and flotillin-2 and a significant fraction of AQP0, MP20, and AQP5 were found in the DRM fraction and were highly sensitive to cholesterol removal. Connexins 46 and 50 were more abundant in nonraft fractions, but a small fraction of each was found in the DRM fraction and was strongly affected by cholesterol removal. Quantification of modified AQP0 confirmed that fatty acylation targeted this protein to membrane raft domains. Conclusions These data represent the first comprehensive profile of the lipid raft proteome of lens fiber cells and provide information on membrane protein organization in these cells. PMID:26747763

  11. Long Life Nickel Electrodes for Nickel-Hydrogen Cells: Fiber Substrates Nickel Electrodes

    NASA Technical Reports Server (NTRS)

    Rogers, Howard H.

    2000-01-01

    Samples of nickel fiber mat electrodes were investigated over a wide range of fiber diameters, electrode thickness, porosity and active material loading levels. Thickness' were 0.040, 0.060 and 0.080 inches for the plaque: fiber diameters were primarily 2, 4, and 8 micron and porosity was 85, 90, and 95%. Capacities of 3.5 in. diameter electrodes were determined in the flooded condition with both 26 and 31% potassium hydroxide solution. These capacity tests indicated that the highest capacities per unit weight were obtained at the 90% porosity level with a 4 micron diameter fiber plaque. It appeared that the thinner electrodes had somewhat better performance, consistent with sintered electrode history. Limited testing with two-positive-electrode boiler plate cells was also carried out. Considerable difficulty with constructing the cells was encountered with short circuits the major problem. Nevertheless, four cells were tested. The cell with 95% porosity electrodes failed during conditioning cycling due to high voltage during charge. Discharge showed that this cell had lost nearly all of its capacity. The other three cells after 20 conditioning cycles showed capacities consistent with the flooded capacities of the electrodes. Positive electrodes made from fiber substrates may well show a weight advantage of standard sintered electrodes, but need considerably more work to prove this statement. A major problem to be investigated is the lower strength of the substrate compared to standard sintered electrodes. Problems with welding of leads were significant and implications that the electrodes would expand more than sintered electrodes need to be investigated. Loading levels were lower than had been expected based on sintered electrode experiences and the lower loading led to lower capacity values. However, lower loading causes less expansion and contraction during cycling so that stress on the substrate is reduced.

  12. Primary cultures of embryonic chick lens cells as a model system to study lens gap junctions and fiber cell differentiation.

    PubMed

    Musil, Linda S

    2012-07-01

    A major limitation in lens gap junction research has been the lack of experimentally tractable ex vivo systems to study the formation and regulation of fiber-type gap junctions. Although immortalized lens-derived cell lines are amenable to both gene transfection and siRNA-mediated knockdown, to our knowledge none are capable of undergoing appreciable epithelial-to-fiber differentiation. Lens central epithelial explants have the converse limitation. A key advance in the field was the development of a primary embryonic chick lens cell culture system by Drs. Sue Menko and Ross Johnson. Unlike central epithelial explants, these cultures also include cells from the peripheral (preequatorial and equatorial) epithelium, which is the most physiologically relevant population for the study of fiber-type gap junction formation. We have modified the Menko/Johnson system and refer to our cultures as dissociated cell-derived monolayer cultures (DCDMLs). We culture DCDMLs without serum to mimic the avascular lens environment and on laminin, the major matrix component of the lens capsule. Here, I review the features of the DCDML system and how we have used it to study lens gap junctions and fiber cell differentiation. Our results demonstrate the power of DCDMLs to generate new findings germane to the mammalian lens and how these cultures can be exploited to conduct experiments that would be impossible, prohibitively expensive and/or difficult to interpret using transgenic animals in vivo.

  13. Fiber-Shaped Perovskite Solar Cells with High Power Conversion Efficiency.

    PubMed

    Qiu, Longbin; He, Sisi; Yang, Jiahua; Deng, Jue; Peng, Huisheng

    2016-05-01

    A perovskite solar cell fiber is created with a high power conversion efficiency of 7.1% through a controllable deposition method. A combination of aligned TiO2 nanotubes, a uniform perovskite layer, and transparent aligned carbon nanotube sheet contributes to the high photovoltaic performance. It is flexible and stable, and can be woven into smart clothes for wearable applications.

  14. FT-IR examination of the development of secondary cell wall in cotton fibers

    USDA-ARS?s Scientific Manuscript database

    The secondary cell wall development of cotton fibers harvested at 18, 20, 24, 28, 32, 36 and 40 days after flowering was examined using attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy. Generally, a progressive intensity increase for bands assigned to cellulose Iß was ...

  15. Structural Plasticity of Dentate Granule Cell Mossy Fibers During the Development of Limbic Epilepsy

    PubMed Central

    Danzer, Steve C.; He, Xiaoping; Loepke, Andreas W.; McNamara, James O.

    2009-01-01

    Altered granule cell≫CA3 pyramidal cell synaptic connectivity may contribute to the development of limbic epilepsy. To explore this possibility, granule cell giant mossy fiber bouton plasticity was examined in the kindling and pilocarpine models of epilepsy using green fluorescent protein-expressing transgenic mice. These studies revealed significant increases in the frequency of giant boutons with satellite boutons 2 days and 1 month after pilocarpine status epilepticus, and increases in giant bouton area at 1 month. Similar increases in giant bouton area were observed shortly after kindling. Finally, both models exhibited plasticity of mossy fiber giant bouton filopodia, which contact GABAergic interneurons mediating feedforward inhibition of CA3 pyramids. In the kindling model, however, all changes were fleeting, having resolved by 1 month after the last evoked seizure. Together, these findings demonstrate striking structural plasticity of granule cell mossy fiber synaptic terminal structure in two distinct models of adult limbic epileptogenesis. We suggest that these plasticities modify local connectivities between individual mossy fiber terminals and their targets, inhibitory interneurons, and CA3 pyramidal cells potentially altering the balance of excitation and inhibition during the development of epilepsy. PMID:19294647

  16. Increased Adipogenesis of Human Adipose-Derived Stem Cells on Polycaprolactone Fiber Matrices

    PubMed Central

    Brännmark, Cecilia; Paul, Alexandra; Ribeiro, Diana; Magnusson, Björn; Brolén, Gabriella; Enejder, Annika; Forslöw, Anna

    2014-01-01

    With accelerating rates of obesity and type 2 diabetes world-wide, interest in studying the adipocyte and adipose tissue is increasing. Human adipose derived stem cells - differentiated to adipocytes in vitro - are frequently used as a model system for white adipocytes, as most of their pathways and functions resemble mature adipocytes in vivo. However, these cells are not completely like in vivo mature adipocytes. Hosting the cells in a more physiologically relevant environment compared to conventional two-dimensional cell culturing on plastic surfaces, can produce spatial cues that drive the cells towards a more mature state. We investigated the adipogenesis of adipose derived stem cells on electro spun polycaprolactone matrices and compared functionality to conventional two-dimensional cultures as well as to human primary mature adipocytes. To assess the degree of adipogenesis we measured cellular glucose-uptake and lipolysis and used a range of different methods to evaluate lipid accumulation. We compared the averaged results from a whole population with the single cell characteristics – studied by coherent anti-Stokes Raman scattering microscopy - to gain a comprehensive picture of the cell phenotypes. In adipose derived stem cells differentiated on a polycaprolactone-fiber matrix; an increased sensitivity in insulin-stimulated glucose uptake was detected when cells were grown on either aligned or random matrices. Furthermore, comparing differentiation of adipose derived stem cells on aligned polycaprolactone-fiber matrixes, to those differentiated in two-dimensional cultures showed, an increase in the cellular lipid accumulation, and hormone sensitive lipase content. In conclusion, we propose an adipocyte cell model created by differentiation of adipose derived stem cells on aligned polycaprolactone-fiber matrices which demonstrates increased maturity, compared to 2D cultured cells. PMID:25419971

  17. Cell fiber-based three-dimensional culture system for highly efficient expansion of human induced pluripotent stem cells.

    PubMed

    Ikeda, Kazuhiro; Nagata, Shogo; Okitsu, Teru; Takeuchi, Shoji

    2017-06-06

    Human pluripotent stem cells are a potentially powerful cellular resource for application in regenerative medicine. Because such applications require large numbers of human pluripotent stem cell-derived cells, a scalable culture system of human pluripotent stem cell needs to be developed. Several suspension culture systems for human pluripotent stem cell expansion exist; however, it is difficult to control the thickness of cell aggregations in these systems, leading to increased cell death likely caused by limited diffusion of gases and nutrients into the aggregations. Here, we describe a scalable culture system using the cell fiber technology for the expansion of human induced pluripotent stem (iPS) cells. The cells were encapsulated and cultured within the core region of core-shell hydrogel microfibers, resulting in the formation of rod-shaped or fiber-shaped cell aggregations with sustained thickness and high viability. By encapsulating the cells with type I collagen, we demonstrated a long-term culture of the cells by serial passaging at a high expansion rate (14-fold in four days) while retaining its pluripotency. Therefore, our culture system could be used for large-scale expansion of human pluripotent stem cells for use in regenerative medicine.

  18. Distribution of parvalbumin-immunoreactive cells and fibers in the monkey temporal lobe: the hippocampal formation.

    PubMed

    Pitkänen, A; Amaral, D G

    1993-05-01

    The distribution of parvalbumin-immunoreactive cells and fibers in the various fields of the hippocampal formation was studied in the macaque monkey. Parvalbumin-immunoreactive neurons had aspiny or sparsely spiny dendrites that often had a beaded appearance; most resembled classically identified interneurons. Parvalbumin-immunoreactive fibers and terminals were confined to certain laminae in each field and generally had a pericellular distribution. In the dentate gyrus, there was a dense pericellular plexus of immunoreactive terminals in the granule cell layer. Except for a narrow supragranular zone, there was a marked paucity of terminals in the molecular and polymorphic cell layers. Immunoreactive neurons were mainly located immediately subjacent to the granule cell layer and comprised a variety of morphological cell types. The three fields of the hippocampus proper (CA3, CA2, and CA1) demonstrated differences in their parvalbumin staining characteristics. In CA3, there was a prominent pericellular terminal plexus in the pyramidal cell layer that was densest distally (closer to CA2). Immunoreactive cells were located either in the pyramidal cell layer, where many had a pyramidal shape and prominent apical and basal dendrites, or in stratum oriens. CA2 had a staining pattern similar to that in CA3, though both the number of labeled cells and the density of the pericellular terminal plexus were greater in CA2. In CA1, there was a markedly lower number of parvalbumin-labeled cells than in CA3 and CA2 and the cells tended to be located in the deep part of the pyramidal cell layer or in stratum oriens. The pyramidal cell layer of CA1 contained a pericellular terminal plexus that was substantially less dense than in CA3 and CA2. At the border between CA1 and the subiculum there was a marked increase in the number of parvalbumin-immunoreactive neurons. The positive cells were scattered throughout the pyramidal cell layer of the subiculum and comprised a variety of

  19. Cells that emerge from embryonic explants produce fibers of type IV collagen

    PubMed Central

    1985-01-01

    Double immunofluorescence staining experiments designed to examine the synthesis and deposition of collagen types I and IV in cultured explants of embryonic mouse lung revealed the presence of connective tissue-like fibers that were immunoreactive with anti-type IV collagen antibodies. This observation is contrary to the widely accepted belief that type IV collagen is found only in sheet-like arrangements beneath epithelia or as a sheath-like layer enveloping bundles of nerve or muscle cells. The extracellular matrix produced by cells that migrate from embryonic mouse lung rudiments in vitro was examined by double indirect immunofluorescence microscopy. Affinity-purified monospecific polyclonal antibodies were used to examine cells after growth on glass or native collagen substrata. The data show that embryonic mesenchymal cells can produce organized fibers of type IV collagen that are not contained within a basement membrane, and that embryonic epithelial cells deposit fibers and strands of type IV collagen beneath their basal surface when grown on glass; however, when grown on a rat tail collagen substratum the epithelial cells produce a fine meshwork. To our knowledge this work represents the first report that type IV collagen can be organized by cells into a fibrous extracellular matrix that is not a basement membrane. PMID:3900085

  20. Phenotypic and Functional Characterization of Human Bone Marrow Stromal Cells in Hollow Fiber Bioreactors

    PubMed Central

    Li, Matthew; Tilles, Arno W.; Milwid, Jack M.; Hammad, Mohamed; Lee, Jungwoo; Yarmush, Martin L.; Parekkadan, Biju

    2011-01-01

    The transplantation of human bone marrow stromal cells (BMSCs) is a novel immunotherapeutic approach that is currently being explored in many clinical settings. Evidence suggests that the efficacy of cell transplantation is directly associated with soluble factors released by human BMSCs. In order to harness these secreted factors, we integrated BMSCs into large-scale hollow-fiber bioreactor devices in which the cells (separated by a semipermeable polyethersulfone (PES) membrane) can directly and continuously release therapeutic factors into the blood stream. BMSCs were found to be rapidly adherent and exhibited long-term viability on PES fibers. The cells also preserved their immunophenotype under physiologic fluid flow rates in the bioreactor, and exhibited no signs of differentiation during device operation, but still retained the capacity to differentiate into osteoblastic lineages. BMSC devices released growth factors and cytokines at comparable levels on a per cell basis to conventional cell culture platforms. Finally, we utilized a potency assay to demonstrate the therapeutic potential of the collected secreted factors from the BMSC devices. In summary, we have shown that culturing BMSCs in a large-scale hollow fiber bioreactor is feasible without deleterious effects on phenotype, thus providing a platform for collecting and delivering the paracrine secretions of these cells. PMID:21710576

  1. Biological effects of asbestos fibers on human cells in vitro--especially on lymphocytes and neutrophils.

    PubMed

    Ueki, A

    2001-04-01

    Biological effects of asbestos fibers were reviewed in relation to the polyclonal activation of human lymphocytes and to the release of free radicals from human neutrophils in vitro. Chrysotile, crocidolite, and amosite asbestos activate CD4+ T lymphocytes polyclonally, followed by activation-induced cell death (a type of apoptosis). The activation is HLA class II dependent, and certain Vbeta repertoire, e.g. Vbeta 5.3, are detected among the fractionated T cells with a high Ca++ level that had been stimulated by asbestos fibers. These observations support the possibility that asbestos acts as a superantigen, and that asbestos stimulate lymphocytes repeatedly in vivo. It has been reported that asbestos-induced cytotoxicity can be suppressed by the scavengers of superoxide or hydroxyl radical. Some of these scavengers such as dimethylsulfoxide (DMSO) or retinoic acid are known as inducers of cell differentiation. The biological functions of DMSO for cell differentiation of HL-60 cells to neutrophils are suppressed by co-culturing of crocidolite asbestos, because DMSO reacts with the hydroxyl radical released after the stimulation with crocidolite and spent itself. Superoxide dismutase (SOD) inhibited the effects of crocidolite, reacting rapidly with *O2- before the secondary release of *OH. It seems to be probable that asbestos fibers, especially crocidolite, suppress the tissue cell differentiation by releasing free radicals and by wasting inducers of cell differentiation as radical scavengers.

  2. Cells on fibers to degrade PAH and upgrade coal

    SciTech Connect

    Clyde, R.

    1997-12-31

    There are over 2000 sites contaminated with PAH`s from coal burning plants. White rot fungus degrades phenanthrene and anthracene, but the fungus needs air to grow. When grown on old cardboard boxes and buried, air is entrapped in the corrugations for growth of the fungus. When holes are put in the valleys of the corrugations and rotated in a half full reactor, drops are formed. Mass transfer to drops is much faster than to a flat surface, as described in Patent 5,256,570, so the fungus grows faster. Low rank coal can be upgraded to more valuable products with the fungus, say some Australians, but the problem is supplying oxygen. Celite can be entrapped in the fibers to ferment coal derived synthesis gas. The paper describes these processes.

  3. Modeling the formation of cell-matrix adhesions on a single 3D matrix fiber.

    PubMed

    Escribano, J; Sánchez, M T; García-Aznar, J M

    2015-11-07

    Cell-matrix adhesions are crucial in different biological processes like tissue morphogenesis, cell motility, and extracellular matrix remodeling. These interactions that link cell cytoskeleton and matrix fibers are built through protein clutches, generally known as adhesion complexes. The adhesion formation process has been deeply studied in two-dimensional (2D) cases; however, the knowledge is limited for three-dimensional (3D) cases. In this work, we simulate different local extracellular matrix properties in order to unravel the fundamental mechanisms that regulate the formation of cell-matrix adhesions in 3D. We aim to study the mechanical interaction of these biological structures through a three dimensional discrete approach, reproducing the transmission pattern force between the cytoskeleton and a single extracellular matrix fiber. This numerical model provides a discrete analysis of the proteins involved including spatial distribution, interaction between them, and study of the different phenomena, such as protein clutches unbinding or protein unfolding.

  4. Measurement of intrinsic optical backscattering characteristics of cells using fiber-guided near infrared light

    PubMed Central

    2010-01-01

    Background Intrinsic optical signals (IOS), which reflect changes in transmittance and scattering light, have been applied to characterize the physiological conditions of target biological tissues. Backscattering approaches allow mounting of the source and detector on the same side of a sample which creates a more compact physical layout of device. This study presents a compact backscattering design using fiber-optic guided near-infrared (NIR) light to measure the amplitude and phase changes of IOS under different osmotic challenges. Methods High-frequency intensity-modulated light was guided via optic fiber, which was controlled by micromanipulator to closely aim at a minimum cluster of cortical neurons. Several factors including the probe design, wavelength selection, optimal measuring distance between the fiber-optical probe and cells were considered. Our experimental setup was tested in cultured cells to observe the relationship between the changes in backscattered NIR light and cellular IOS, which is believed mainly caused by cell volume changes in hypo/hyperosmotic solutions (± 20, ± 40 and ± 60 mOsm). Results The critical parameters of the current setup including the optimal measuring distance from fiber-optical probe to target tissue and the linear relationship between backscattering intensity and cell volume were determined. The backscattering intensity was found to be inversely proportional to osmotic changes. However, the phase shift exhibited a nonlinear feature and reached a plateau at hyperosmotic solution. Conclusions Our study indicated that the backscattering NIR light guided by fiber-optical probe makes it a potential alternative for continuous observation of intrinsic optical properties of cell culture under varied physical or chemical challenges. PMID:20184751

  5. Necrotic regions are absent in fiber-shaped cell aggregates, approximately 100 μm in diameter.

    PubMed

    Takei, Takayuki; Kitazono, Jyunpei; Tanaka, Sadao; Nishimata, Hiroto; Yoshida, Masahiro

    2016-01-01

    Microscopic, fiber-shaped cell aggregates, have been used as building blocks for fabricating macroscopic three-dimensional tissue architectures, in the field of tissue engineering. In this study, we examined the occurrence of necrotic regions in the most widely used, fiber-shaped cell aggregates, approximately 100 μm in diameter. Alginate hydrogel hollow microfibers were used as templates for the cell aggregates. We demonstrated negligible necrotic region formation occurred in the cell aggregates formed in the hollow microfibers. Furthermore, we improved on previously-reported methods for preparing the hollow microfibers to avoid common microfiber tangling during the fiber preparation process.

  6. Tmem2 regulates cell-matrix interactions that are essential for muscle fiber attachment

    PubMed Central

    2016-01-01

    Skeletal muscle morphogenesis depends upon interactions between developing muscle fibers and the extracellular matrix (ECM) that anchors fibers to the myotendinous junction (MTJ). The pathways that organize the ECM and regulate its engagement by cell-matrix adhesion complexes (CMACs) are therefore essential for muscle integrity. Here, we demonstrate the impact of transmembrane protein 2 (tmem2) on cell-matrix interactions during muscle morphogenesis in zebrafish. Maternal-zygotic tmem2 mutants (MZtmem2) exhibit muscle fiber detachment, in association with impaired laminin organization and ineffective fibronectin degradation at the MTJ. Similarly, disorganized laminin and fibronectin surround MZtmem2 cardiomyocytes, which could account for their hindered movement during cardiac morphogenesis. In addition to ECM defects, MZtmem2 mutants display hypoglycosylation of α-dystroglycan within the CMAC, which could contribute to the observed fiber detachment. Expression of the Tmem2 ectodomain can rescue aspects of the MZtmem2 phenotype, consistent with a possible extracellular function of Tmem2. Together, our results suggest that Tmem2 regulates cell-matrix interactions by affecting both ECM organization and CMAC activity. These findings evoke possible connections between the functions of Tmem2 and the etiologies of congenital muscular dystrophies, particularly dystroglycanopathies. PMID:27471259

  7. Tmem2 regulates cell-matrix interactions that are essential for muscle fiber attachment.

    PubMed

    Ryckebüsch, Lucile; Hernandez, Lydia; Wang, Carole; Phan, Jenny; Yelon, Deborah

    2016-08-15

    Skeletal muscle morphogenesis depends upon interactions between developing muscle fibers and the extracellular matrix (ECM) that anchors fibers to the myotendinous junction (MTJ). The pathways that organize the ECM and regulate its engagement by cell-matrix adhesion complexes (CMACs) are therefore essential for muscle integrity. Here, we demonstrate the impact of transmembrane protein 2 (tmem2) on cell-matrix interactions during muscle morphogenesis in zebrafish. Maternal-zygotic tmem2 mutants (MZtmem2) exhibit muscle fiber detachment, in association with impaired laminin organization and ineffective fibronectin degradation at the MTJ. Similarly, disorganized laminin and fibronectin surround MZtmem2 cardiomyocytes, which could account for their hindered movement during cardiac morphogenesis. In addition to ECM defects, MZtmem2 mutants display hypoglycosylation of α-dystroglycan within the CMAC, which could contribute to the observed fiber detachment. Expression of the Tmem2 ectodomain can rescue aspects of the MZtmem2 phenotype, consistent with a possible extracellular function of Tmem2. Together, our results suggest that Tmem2 regulates cell-matrix interactions by affecting both ECM organization and CMAC activity. These findings evoke possible connections between the functions of Tmem2 and the etiologies of congenital muscular dystrophies, particularly dystroglycanopathies. © 2016. Published by The Company of Biologists Ltd.

  8. Transport of gases and liquids through dense microbial cell aggregates cultured within hollow fiber membrane bioreactors

    SciTech Connect

    Libicki, S.B.

    1985-01-01

    The transport properties of liquids and dissolved gases in microbial cell aggregates were examined. An annular hollow fiber membrane bioreactor designed for this purpose, allowed a cell aggregate of well-defined geometry to be cultured between two retaining fibers. The transport of an inert substance through a lamellar annular hollow fiber reactor has been modeled. Calculations showed that Starling flow, a weak toroidal flow in the reactor, may account for a large fraction of the solute transport. The theoretical predictions were verified experimentally. The effective diffusive permeability of a dissolved tracer (nitrous oxide) was measured in dense microbial cell aggregates (Escherichia coli) ranging from 15% to 95% cell volume fraction. The results showed that the diffusive permeability is a monotonically decreasing function of cell volume fraction and can be described by the Hashin-Shtrikman bounds on transport in a two phase material. Using these bounds, the effective diffusive permeability of nitrous oxide in E. coli cells at 37/sup 0/C was estimated to be 8.6 x 10/sup -9/ mol/m s or 0.24 +/- 0.03 that of the diffusive permeability of the surrounding interstitial fluid. Similar measurements of the diffusive permeability of nitrous oxide in artificial aggregates (compacted cells) and disrupted microbial cells yielded virtually identical results, showing that cell structure and viability have only a small effect. The Darcy permeability of the same microbial aggregates, measured under very low flow conditions, was found to be only weakly dependent on cell volume fraction. Electron micrographs indicate that this was due to clustering of the cells which increased the effective particle size within the cell aggregate.

  9. Efficient Gene Transduction of Dispersed Islet Cells in Culture Using Fiber-Modified Adenoviral Vectors

    PubMed Central

    Hanayama, Hiroyuki; Ohashi, Kazuo; Utoh, Rie; Shimizu, Hirofumi; Ise, Kazuya; Sakurai, Fuminori; Mizuguchi, Hiroyuki; Tsuchiya, Hiroyuki; Okano, Teruo; Gotoh, Mitsukazu

    2015-01-01

    To establish novel islet-based therapies, our group has recently developed technologies for creating functional neo-islet tissues in the subcutaneous space by transplanting monolithic sheets of dispersed islet cells (islet cell sheets). Improving cellular function and viability are the next important challenges for enhancing the therapeutic effects. This article describes the adenoviral vector-mediated gene transduction of dispersed islet cells under culture conditions. Purified pancreatic islets were obtained from Lewis rats and dissociated into single islet cells. Cells were plated onto laminin-5-coated temperature-responsive polymer poly(N-isopropylacrylamide)-immobilized plastic dishes. At 0 h, islet cells were infected for 1 h with either conventional type 5 adenoviral vector (Ad-CA-GFP) or fiber-modified adenoviral vector (AdK7-CA-GFP) harboring a polylysine (K7) peptide in the C terminus of the fiber knob. We investigated gene transduction efficiency at 48 h after infection and found that AdK7-CA-GFP yielded higher transduction efficiencies than Ad-CA-GFP at a multiplicity of infection (MOI) of 5 and 10. For AdK7-CA-GFP at MOI = 10, 84.4 ± 1.5% of islet cells were found to be genetically transduced without marked vector infection-related cellular damage as determined by viable cell number and lactate dehydrogenase (LDH) release assay. After AdK7-CA-GFP infection at MOI = 10, cells remained attached and expanded to nearly full confluency, showing that this adenoviral infection protocol is a feasible approach for creating islet cell sheets. We have shown that dispersed and cultured islet cells can be genetically modified efficiently using fiber-modified adenoviral vectors. Therefore, this gene therapy technique could be used for cellular modification or biological assessment of dispersed islet cells. PMID:26858906

  10. Retinal flat cells participate in the formation of fibers by retinal neuroblasts in vitro. Time lapse video studies.

    PubMed

    Li, H P; Sheffield, J B

    1986-03-01

    Freshly dissociated cells from embryonic chick neural retinas grow in characteristic patterns on flat cells or on chick embryo mesodermal cells. A striking difference between the two patterns is that the cells grown on flat cells are interconnected by a complex network of fibers, whereas those grown on mesodermal cells are aggregated into clusters that remain relatively isolated within the mesodermal monolayer. Analysis by time-lapse video microscopy indicates that two processes produce the fibers. (1) Fibers grow out by the extension of growth cones from cells within aggregates. (2) Neuronal cell aggregates that attach to two flat cells are pulled apart by the movement of the cells beneath them. As the aggregate is pulled apart, portions of the cells remain attached to the two halves, and their cytoplasm is drawn into thin fibers. The lack of fibers on a mesodermal substrate is due to two factors: (1) Aggregates are widely spaced on the substrate surface and do not come into contact often. (2) On those occasions when they do come into contact, the movement of the monolayer is so vigorous that emerging fibers are torn.

  11. Characteristics of mesophase pitch-based carbon fibers as anode materials for lithium secondary cells

    SciTech Connect

    Tamaki, Toshio

    1995-12-31

    Mesophase pitch-based Carbon Fibers (MPCF) have been investigated as anode materials for lithium secondary cells by examining their physical and electrochemical properties. Discharge capacity and initial charge-discharge efficiency of the materials were studied in relation to the heat treatment temperatures of MPCF. Carbon fiber which was heat treated at about 3,000 C gave the highest discharge capacity (over 300 mAh/g), good efficiency (92%) and superior current capability (600 mA/g). Carbon fiber heat treated at less than 1,000 C, also has superior discharge capacity (over 500 mAh/g) at the first cycle, however efficiency was relatively low. Some of the relationships between structure of MPCF and electrochemical properties are discussed.

  12. The development of a potassium-sulfide glass fiber cell and studies on impurities in alkali metal-sulfur cells

    NASA Technical Reports Server (NTRS)

    Tsang, F. Y.

    1977-01-01

    Potassium sulfur rechargeable cells, having as the electrolyte the thin walls of hollow glass fibers made from permeable glass, were developed. The cells had short lives, probably due to the construction materials and impurities in the potassium. The effect of the impurities in the analogous NA-S system was studied. Calcium, potassium, and NaOH/oxide impurities caused increased resistance or corrosion of the glass fibers. For long lived cell operation, the Na must contain less than 1 ppm Ca and less than a few ppm of hydroxide/oxide. Up to 150 ppm K can be tolerated. After purification of the Na anolyte, cell lifetimes in excess of 1000 deep charge-discharge cycles or over 8 months on continuous cycling at 10-30 percent depth of discharge were obtained.

  13. The dual functions of WLIM1a in cell elongation and secondary wall formation in developing cotton fibers.

    PubMed

    Han, Li-Bo; Li, Yuan-Bao; Wang, Hai-Yun; Wu, Xiao-Min; Li, Chun-Li; Luo, Ming; Wu, Shen-Jie; Kong, Zhao-Sheng; Pei, Yan; Jiao, Gai-Li; Xia, Gui-Xian

    2013-11-01

    LIN-11, Isl1 and MEC-3 (LIM)-domain proteins play pivotal roles in a variety of cellular processes in animals, but plant LIM functions remain largely unexplored. Here, we demonstrate dual roles of the WLIM1a gene in fiber development in upland cotton (Gossypium hirsutum). WLIM1a is preferentially expressed during the elongation and secondary wall synthesis stages in developing fibers. Overexpression of WLIM1a in cotton led to significant changes in fiber length and secondary wall structure. Compared with the wild type, fibers of WLIM1a-overexpressing plants grew longer and formed a thinner and more compact secondary cell wall, which contributed to improved fiber strength and fineness. Functional studies demonstrated that (1) WLIM1a acts as an actin bundler to facilitate elongation of fiber cells and (2) WLIM1a also functions as a transcription factor to activate expression of Phe ammonia lyase-box genes involved in phenylpropanoid biosynthesis to build up the secondary cell wall. WLIM1a localizes in the cytosol and nucleus and moves into the nucleus in response to hydrogen peroxide. Taken together, these results demonstrate that WLIM1a has dual roles in cotton fiber development, elongation, and secondary wall formation. Moreover, our study shows that lignin/lignin-like phenolics may substantially affect cotton fiber quality; this finding may guide cotton breeding for improved fiber traits.

  14. Biomimics of fungal cell-cell recognition by use of lectin-coated nylon fibers.

    PubMed Central

    Inbar, J; Chet, I

    1992-01-01

    When the mycoparasitic, biocontrol fungus Trichoderma harzianum was allowed to grow on nylon fibers treated with concanavalin A or Sclerotium rolfsii lectin, it coiled around the nylon fibers and produced hooks in a pattern similar to that observed with the real host hyphae. The incidence of interaction between T. harzianum and S. rolfsii lectin-treated fibers was significantly higher than that of the controls (untreated or blocked activated fibers). These findings provide direct evidence for the role of lectins in mycoparasitism. Images PMID:1732197

  15. GABAergic cells are the major postsynaptic targets of mossy fibers in the rat hippocampus.

    PubMed

    Acsády, L; Kamondi, A; Sík, A; Freund, T; Buzsáki, G

    1998-05-01

    Dentate granule cells communicate with their postsynaptic targets by three distinct terminal types. These include the large mossy terminals, filopodial extensions of the mossy terminals, and smaller en passant synaptic varicosities. We examined the postsynaptic targets of mossy fibers by combining in vivo intracellular labeling of granule cells, immunocytochemistry, and electron microscopy. Single granule cells formed large, complex "mossy" synapses on 11-15 CA3 pyramidal cells and 7-12 hilar mossy cells. In contrast, GABAergic interneurons, identified with immunostaining for substance P-receptor, parvalbumin, and mGluR1a-receptor, were selectively innervated by very thin (filopodial) extensions of the mossy terminals and by small en passant boutons in both the hilar and CA3 regions. These terminals formed single, often perforated, asymmetric synapses on the cell bodies, dendrites, and spines of GABAergic interneurons. The number of filopodial extensions and small terminals was 10 times larger than the number of mossy terminals. These findings show that in contrast to cortical pyramidal neurons, (1) granule cells developed distinct types of terminals to affect interneurons and pyramidal cells and (2) they innervated more inhibitory than excitatory cells. These findings may explain the physiological observations that increased activity of granule cells suppresses the overall excitability of the CA3 recurrent system and may form the structural basis of the target-dependent regulation of glutamate release in the mossy fiber system.

  16. Ultrastructural Analysis of the Human Lens Fiber Cell Remodeling Zone and the Initiation of Cellular Compaction

    PubMed Central

    Costello, M. Joseph; Mohamed, Ashik; Gilliland, Kurt O.; Fowler, W. Craig; Johnsen, Sönke

    2013-01-01

    The purpose is to determine the nature of the cellular rearrangements occurring through the remodeling zone (RZ) in human donor lenses, identified previously by confocal microscopy to be about 100 µm from the capsule. Human donor lenses were fixed with 10% formalin followed by 4% paraformaldehyde prior to processing for transmission electron microscopy. Of 27 fixed lenses, ages 22, 55 and 92 years were examined in detail. Overview electron micrographs confirmed the loss of cellular organization present in the outer cortex (80 µm thick) as the cells transitioned into the RZ. The transition occurred within a few cell layers and fiber cells in the RZ completely lost their classical hexagonal cross-sectional appearance. Cell interfaces became unusually interdigitated and irregular even though the radial cell columns were retained. Gap junctions appeared to be unaffected. After the RZ (40 µm thick), the cells were still irregular but more recognizable as fiber cells with typical interdigitations and the appearance of undulating membranes. Cell thickness was irregular after the RZ with some cells compacted, while others were not, up to the zone of full compaction in the adult nucleus. Similar dramatic cellular changes were observed within the RZ for each lens regardless of age. Because the cytoskeleton controls cell shape, dramatic cellular rearrangements that occur in the RZ most likely are due to alterations in the associations of crystallins to the lens-specific cytoskeletal beaded intermediate filaments. It is also likely that cytoskeletal attachments to membranes are altered to allow undulating membranes to develop. PMID:24183661

  17. Sacral Neural Crest-Derived Cells Enter the Aganglionic Colon of Ednrb−/− Mice Along Extrinsic Nerve Fibers

    PubMed Central

    Erickson, Christopher S.; Zaitoun, Ismail; Haberman, Kathryn M.; Gosain, Ankush; Druckenbrod, Noah R.; Epstein, Miles L.

    2012-01-01

    Both vagal and sacral neural crest cells contribute to the enteric nervous system in the hindgut. Because it is difficult to visualize sacral crest cells independently of vagal crest, the nature and extent of the sacral crest contribution to the enteric nervous system are not well established in rodents. To overcome this problem we generated mice in which only the fluorescent protein-labeled sacral crest are present in the terminal colon. We found that sacral crest cells were associated with extrinsic nerve fibers. We investigated the source, time of appearance, and characteristics of the extrinsic nerve fibers found in the aganglionic colon. We observed that the pelvic ganglion neurons contributed a number of extrinsic fibers that travel within the hindgut between circular and longitudinal muscles and within the submucosa and serosa. Sacral crest-derived cells along these fibers diminished in number from fetal to post-natal stages. A small number of sacral crest-derived cells were found between the muscle layers and expressed the neuronal marker Hu. We conclude that sacral crest cells enter the hindgut by advancing on extrinsic fibers and, in aganglionic preparations, they form a small number of neurons at sites normally occupied by myenteric ganglia. We also examined the colons of ganglionated preparations and found sacral crest-derived cells associated with both extrinsic nerve fibers and nascent ganglia. Extrinsic nerve fibers serve as a route of entry for both rodent and avian sacral crest into the hindgut. PMID:21858821

  18. Sacral neural crest-derived cells enter the aganglionic colon of Ednrb-/- mice along extrinsic nerve fibers.

    PubMed

    Erickson, Christopher S; Zaitoun, Ismail; Haberman, Kathryn M; Gosain, Ankush; Druckenbrod, Noah R; Epstein, Miles L

    2012-02-15

    Both vagal and sacral neural crest cells contribute to the enteric nervous system in the hindgut. Because it is difficult to visualize sacral crest cells independently of vagal crest, the nature and extent of the sacral crest contribution to the enteric nervous system are not well established in rodents. To overcome this problem we generated mice in which only the fluorescent protein-labeled sacral crest are present in the terminal colon. We found that sacral crest cells were associated with extrinsic nerve fibers. We investigated the source, time of appearance, and characteristics of the extrinsic nerve fibers found in the aganglionic colon. We observed that the pelvic ganglion neurons contributed a number of extrinsic fibers that travel within the hindgut between circular and longitudinal muscles and within the submucosa and serosa. Sacral crest-derived cells along these fibers diminished in number from fetal to postnatal stages. A small number of sacral crest-derived cells were found between the muscle layers and expressed the neuronal marker Hu. We conclude that sacral crest cells enter the hindgut by advancing on extrinsic fibers and, in aganglionic preparations, they form a small number of neurons at sites normally occupied by myenteric ganglia. We also examined the colons of ganglionated preparations and found sacral crest-derived cells associated with both extrinsic nerve fibers and nascent ganglia. Extrinsic nerve fibers serve as a route of entry for both rodent and avian sacral crest into the hindgut.

  19. Note: Compact optical fiber coupler for diamond anvil high pressure cells

    NASA Astrophysics Data System (ADS)

    Pugh, E.

    2013-10-01

    A compact optical fiber coupler has been developed to allow transmission of light through an optical fiber to and from the high pressure region of a diamond anvil high pressure cell. Despite its small size the coupler has focusing adjustments and optics, which allows the light to be focused precisely on the sample within the pressure cell. The coupler is suitable for a wide range of optical measurements and particularly for high pressure measurements at low temperatures in cryostats with no optical windows. The use of the coupler to determine the pressure in a diamond anvil cell at 1.2 K using the ruby fluorescence spectra of ruby is demonstrated. The small size of the coupler and its construction out of nonmagnetic beryllium copper makes it suitable for use in high magnetic fields and for magnetization experiments.

  20. High-capacity lithium-ion cells using graphitized mesophase-pitch-based carbon fiber anodes

    NASA Astrophysics Data System (ADS)

    Ohsaki, Takahisa; Kanda, Motoya; Aoki, Yoshiyasu; Shiroki, Hiroyuki; Suzuki, Shintaro

    We have developed high-capacity lithium-ion cells using graphitized mesophase-pitch-based carbon fiber (MCF) as an anode material. The graphitized MCF is a highly graphitized carbon fiber with a radial-like texture in the cross section. This structure contributes to the rapid diffusion of lithium ions inside the carbon fiber. The diffusion coefficient of lithium ions in the graphitized MCF was one order of magnitude larger than those for graphite, resulting in an excellent high-rate performance of the carbon electrode. The graphitized MCF anode showed larger capacity, a higher rate capability, and better reversibility than the graphite anode. The 863448 size (8.6 mm × 34 mm × 48 mm) prismatic cell with the graphitized MCF anode exhibited a large capacity of > 1000 mAh. At 3 A discharge, the prismatic cell had 95% of its capacity at 0.5 A discharge with a mid-discharge voltage of 3.35 V. The cell maintained > 85% of its initial capacity after 500 cycles and showed high capacity at -20 °C. It has thus been demonstrated that the prismatic cell using the graphitized MCF anode has excellent performance, and is an attractive choice for the power sources of cellular phones and other appliances.

  1. Distributed fiber-optic sensing in a high-temperature solid-oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Buric, M.; Ohodnicki, P.; Yan, A.; Huang, S.; Chen, K. P.

    2016-09-01

    High temperature solid-oxide fuel cells (SOFCs) present a challenging harsh environment for sensor systems with temperatures above 800C and ambient hydrogen concentration potentially ranging from 0-100% across the cell's anode. A strong gradient exists in both gas concentration and temperature from the fuel-inlet to outlet as fuel is consumed across the cell. We report a technique for measuring the spatial distribution of temperature along a solid-oxide fuel-cell interconnect channel using a distributed interrogation system coupled with a single-mode fiber optic thin-film evanescent wave absorption sensor. These sensors are to be operated inside an operating fuel-cell stack yielding spatially distributed measurements with sub-millimeter accuracy. Details are presented pertinent to the stable operation of silica optical fibers in the presence of high hydrogen concentration which can induce optical fiber losses. The stability of Rayleigh scattering centers is discussed with regard to the operational environment. The potential for extension of the approach to chemical (i.e. hydrogen) sensing as well as dual hydrogen/temperature sensor fabrication and stabilization are also briefly discussed.

  2. Three-dimensional fiber deposition of cell-laden, viable, patterned constructs for bone tissue printing.

    PubMed

    Fedorovich, Natalja E; De Wijn, Joost R; Verbout, Abraham J; Alblas, Jacqueline; Dhert, Wouter J A

    2008-01-01

    Organ or tissue printing, a novel approach in tissue engineering, creates layered, cell-laden hydrogel scaffolds with a defined three-dimensional (3D) structure and organized cell placement. In applying the concept of tissue printing for the development of vascularized bone grafts, the primary focus lies on combining endothelial progenitors and bone marrow stromal cells (BMSCs). Here we characterize the applicability of 3D fiber deposition with a plotting device, Bioplotter, for the fabrication of spatially organized, cell-laden hydrogel constructs. The viability of printed BMSCs was studied in time, in several hydrogels, and extruded from different needle diameters. Our findings indicate that cells survive the extrusion and that their subsequent viability was not different from that of unprinted cells. The applied extrusion conditions did not affect cell survival, and BMSCs could subsequently differentiate along the osteoblast lineage. Furthermore, we were able to combine two distinct cell populations within a single scaffold by exchanging the printing syringe during deposition, indicating that this 3D fiber deposition system is suited for the development of bone grafts containing multiple cell types.

  3. Overcharge studies of carbon fiber composite-based lithium-ion cells

    NASA Astrophysics Data System (ADS)

    Hossain, S.; Kim, Y.-K.; Saleh, Y.; Loutfy, R.

    Prototype lithium-ion pouch cells of 5.5 Ah have been fabricated with carbon fiber composite anodes, LiCoO 2 cathodes, and LiPF 6 electrolyte to investigate the overcharge characteristics of these cells at the 1 C rate. The cells were made with anode to cathode capacity (A/C) ratios of 1.0 and 1.1. The cells were first examined for charge-discharge characteristics at different rates in order to determine the delivered capacity, specific energy and energy density and rate capability, and to ensure that the cells are suitable for overcharge studies. The current, voltage, and temperature responses during overcharge to 12 V were recorded. Maximum temperatures of 65 and 85 °C were observed with the cells with A/C equal to 1.1 and 1.0, respectively. The overcharged cells were dissected in an inert atmosphere and their components were analyzed using scanning electron microscopy and x-ray fluorescence spectroscopy. It is believed that a relatively low amount of heat is generated with carbon fiber composite-based lithium-ion cells and a separator shutdown mechanism is operative in the cell system which prevents fire or explosion during overcharge.

  4. Secondary cell wall development in cotton fibers as examined with attenuated total reflection Fourier transform infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Cotton fibers harvested at 18, 20, 24, 28, 32, 36 and 40 days after flowering were examined using attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy. The selected harvesting points coincide with secondary cell wall (SCW) development in the fibers. Progressive but moderat...

  5. Secreted frizzled-related protein disrupts PCP in eye lens fiber cells that have polarised primary cilia

    PubMed Central

    Sugiyama, Yuki; Stump, Richard J. W.; Nguyen, Anke; Wen, Li; Chen, Yongjuan; Wang, Yanshu; Murdoch, Jennifer N.; Lovicu, Frank J.; McAvoy, John W.

    2009-01-01

    Planar cell polarity (PCP) signaling polarises cells along tissue axes. Although pathways involved are becoming better understood, outstanding issues include; (i) existence/identity of cues that orchestrate global polarisation in tissues, and (ii) the generality of the link between polarisation of primary cilia and asymmetric localisation of PCP proteins. Mammalian lenses are mainly comprised of epithelial-derived fiber cells. Concentrically arranged fibers are precisely aligned as they elongate along the anterior-posterior axis and orientate towards lens poles where they meet fibers from other segments to form characteristic sutures. We show that lens exhibits PCP, with each fiber cell having a apically situated cilium and in most cases this is polarised towards the anterior pole. Frizzled and other PCP proteins are also asymmetrically localised along the equatorial-anterior axis. Mutations in core PCP genes Van Gogh-like 2 and Celsr1 perturb oriented fiber alignment and suture formation. Suppression of the PCP pathway by overexpressing Sfrp2, shows that whilst local groups of fibers are often similarly oriented, they lack global orientation; consequently when local groups of fibers with different orientations meet they form multiple, small, ectopic suture-like configurations. This indicates that this extracellular inhibitor disrupts a global polarising signal that utilises a PCP-mediated mechanism to coordinate the global alignment and orientation of fibers to lens poles. PMID:19968984

  6. Identification and characterization of plasma membrane aquaporins isolated from fiber cells of Calotropis procera

    PubMed Central

    Aslam, Usman; Khatoon, Asia; Cheema, Hafiza Masooma Naseer; Bashir, Aftab

    2013-01-01

    Calotropis procera, commonly known as “milkweed”, possesses long seed trichomes for seed dispersal and has the ability to survive under harsh conditions such as drought and salinity. Aquaporins are water channel proteins expressed in all land plants, divided into five subfamilies plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), NOD26-like proteins (NIPs), small basic intrinsic proteins (SIPs), and the unfamiliar X intrinsic proteins (XIPs). PIPs constitute the largest group of water channel proteins that are involved in different developmental and regulatory mechanisms including water permeability, cell elongation, and stomata opening. Aquaporins are also involved in abiotic stress tolerance and cell expansion mechanisms, but their role in seed trichomes (fiber cells) has never been investigated. A large number of clones isolated from C. procera fiber cDNA library showed sequence homology to PIPs. Both expressed sequence tags (ESTs) and real-time polymerase chain reaction (PCR) studies revealed that the transcript abundance of this gene family in fiber cells of C. procera is greater than that of cotton. Full-length cDNAs of CpPIP1 and CpPIP2 were isolated from C. procera fiber cDNA library and used for constructing plant expression vectors under constitutive (2×35S) and trichome-specific (GhLTP3) promoters. Transgenic tobacco plants were developed via Agrobacterium-mediated transformation. The phenotypic characteristics of the plants were observed after confirming the integration of transgene in plants. It was observed that CpPIP2 expression cassette under 2×35S and GhLTP3 promoter enhanced the numbers of stem and leave trichomes. However, 2×35S::CpPIP2 has a more amplified effect on trichome density and length than GhLTP3::CpPIP2 and other PIP constructs. These findings imply the role of C. procera PIP aquaporins in fiber cell elongation. The PIPs-derived cell expansion mechanism may be exploited through transgenic approaches

  7. Identification and characterization of plasma membrane aquaporins isolated from fiber cells of Calotropis procera.

    PubMed

    Aslam, Usman; Khatoon, Asia; Cheema, Hafiza Masooma Naseer; Bashir, Aftab

    2013-07-01

    Calotropis procera, commonly known as "milkweed", possesses long seed trichomes for seed dispersal and has the ability to survive under harsh conditions such as drought and salinity. Aquaporins are water channel proteins expressed in all land plants, divided into five subfamilies plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), NOD26-like proteins (NIPs), small basic intrinsic proteins (SIPs), and the unfamiliar X intrinsic proteins (XIPs). PIPs constitute the largest group of water channel proteins that are involved in different developmental and regulatory mechanisms including water permeability, cell elongation, and stomata opening. Aquaporins are also involved in abiotic stress tolerance and cell expansion mechanisms, but their role in seed trichomes (fiber cells) has never been investigated. A large number of clones isolated from C. procera fiber cDNA library showed sequence homology to PIPs. Both expressed sequence tags (ESTs) and real-time polymerase chain reaction (PCR) studies revealed that the transcript abundance of this gene family in fiber cells of C. procera is greater than that of cotton. Full-length cDNAs of CpPIP1 and CpPIP2 were isolated from C. procera fiber cDNA library and used for constructing plant expression vectors under constitutive (2×35S) and trichome-specific (GhLTP3) promoters. Transgenic tobacco plants were developed via Agrobacterium-mediated transformation. The phenotypic characteristics of the plants were observed after confirming the integration of transgene in plants. It was observed that CpPIP2 expression cassette under 2×35S and GhLTP3 promoter enhanced the numbers of stem and leave trichomes. However, 2×35S::CpPIP2 has a more amplified effect on trichome density and length than GhLTP3::CpPIP2 and other PIP constructs. These findings imply the role of C. procera PIP aquaporins in fiber cell elongation. The PIPs-derived cell expansion mechanism may be exploited through transgenic approaches for

  8. Detection of Low Levels of Listeria monocytogenes Cells by Using a Fiber-Optic Immunosensor

    PubMed Central

    Geng, Tao; Morgan, Mark T.; Bhunia, Arun K.

    2004-01-01

    Biosensor technology has a great potential to meet the need for sensitive and nearly real-time microbial detection from foods. An antibody-based fiber-optic biosensor to detect low levels of Listeria monocytogenes cells following an enrichment step was developed. The principle of the sensor is a sandwich immunoassay where a rabbit polyclonal antibody was first immobilized on polystyrene fiber waveguides through a biotin-streptavidin reaction to capture Listeria cells on the fiber. Capture of cells on the fibers was confirmed by scanning electron microscopy. A cyanine 5-labeled murine monoclonal antibody, C11E9, was used to generate a specific fluorescent signal, which was acquired by launching a 635-nm laser light from an Analyte 2000 and collected by a photodetector at 670 to 710 nm. This immunosensor was specific for L. monocytogenes and showed a significantly higher signal strength than for other Listeria species or other microorganisms, including Escherichia coli, Enterococcus faecalis, Salmonella enterica, Lactobacillus plantarum, Carnobacterium gallinarum, Hafnia alvei, Corynebacterium glutamicum, Enterobacter aerogenes, Pseudomonas aeruginosa, and Serratia marcescens, in pure or in mixed-culture setup. Fiber-optic results could be obtained within 2.5 h of sampling. The sensitivity threshold was about 4.3 × 103 CFU/ml for a pure culture of L. monocytogenes grown at 37°C. When L. monocytogenes was mixed with lactic acid bacteria or grown at 10°C with 3.5% NaCl, the detection threshold was 4.1 × 104 or 2.8 × 107 CFU/ml, respectively. In less than 24 h, this method could detect L. monocytogenes in hot dog or bologna naturally contaminated or artificially inoculated with 10 to 1,000 CFU/g after enrichment in buffered Listeria enrichment broth. PMID:15466560

  9. Protein-coated poly(L-lactic acid) fibers provide a substrate for differentiation of human skeletal muscle cells.

    PubMed

    Cronin, Elizabeth M; Thurmond, Frederick A; Bassel-Duby, Rhonda; Williams, R Sanders; Wright, Woodring E; Nelson, Kevin D; Garner, Harold R

    2004-06-01

    Tissue engineering represents a potential method for repairing damaged skeletal muscle tissue. Extracellular matrix (ECM) proteins were evaluated for their ability to aid in cell attachment, whereas a poly(L-lactic acid) (PLLA) fiber scaffold was tested as a substrate for the differentiation of human skeletal muscle cells. In comparison to uncoated or gelatin-coated PLLA films, cell attachment increased significantly (p < 0.001) on PLLA films coated with ECM gel, fibronectin, or laminin. Myoblasts differentiated into multinucleated myofibers on ECM gel-coated PLLA fibers, and expressed muscle markers such as myosin and alpha-actinin. Oligonucleotide microarray analysis showed similar gene expression profiles for human skeletal muscle cells on ECM gel-coated PLLA fibers as to that observed for myofibers on tissue culture plates. Therefore, PLLA fibers coated with ECM proteins provide a scaffold for the development of skeletal muscle tissue for tissue engineering and cell transplantation applications.

  10. Egestion of asbestos fibers in Tetrahymena results in early morphological abnormalities. A step in the induction of heterogeneous cell lines?

    PubMed

    Hjelm, K K

    1989-01-01

    In Tetrahymena populations exposed to crocidolite asbestos fibers, many cells develop morphological abnormalities within 1-2 hours. The abnormalities are mainly large or small protrusions or indentations, or flattened parts of the cell surface and most often located in the posterior part of the cell. They are formed repeatedly in all cells but are also continuously repaired so that the fraction of cells affected represents an equilibrium between these two processes. Their formation is connected with egestion of the large bundles of fibers formed by phagocytosis. Such effects of egestion of fibers do not seem to have been reported previously. Egestion of a bundle of fibers is much slower than for other types of undigestible residues. In contrast to normal exocytosis occurring invariably at the cytoproct, egestion of asbestos often occurs in the posterior part of the cell outside the cytoproct. To my knowledge this is the first reported case of either very slow or extra-cytoproctal egestion in Tetrahymena. Cells with large abnormalities have a greater tendency to develop into "early heterogeneous" cells than the average abnormal cell. Some of these give rise to hereditarily stable heterogeneous cell lines of Tetrahymena. The morphological abnormalities are probably caused by mechanical action of the crocidolite fibers resulting in local damage of the cytoskeletal elements responsible for normal cell shape. The heterogenous cell lines may arise when cellular structures carrying non-genic cytotactically inherited information are modified. The relevance of these ideas to the induction of cancer by asbestos is briefly discussed.

  11. Fibroblast growth factor receptor signaling is essential for lens fiber cell differentiation.

    PubMed

    Zhao, Haotian; Yang, Tianyu; Madakashira, Bhavani P; Thiels, Cornelius A; Bechtle, Chad A; Garcia, Claudia M; Zhang, Huiming; Yu, Kai; Ornitz, David M; Beebe, David C; Robinson, Michael L

    2008-06-15

    The vertebrate lens provides an excellent model to study the mechanisms that regulate terminal differentiation. Although fibroblast growth factors (FGFs) are thought to be important for lens cell differentiation, it is unclear which FGF receptors mediate these processes during different stages of lens development. Deletion of three FGF receptors (Fgfr1-3) early in lens development demonstrated that expression of only a single allele of Fgfr2 or Fgfr3 was sufficient for grossly normal lens development, while mice possessing only a single Fgfr1 allele developed cataracts and microphthalmia. Profound defects were observed in lenses lacking all three Fgfrs. These included lack of fiber cell elongation, abnormal proliferation in prospective lens fiber cells, reduced expression of the cell cycle inhibitors p27(kip1) and p57(kip2), increased apoptosis and aberrant or reduced expression of Prox1, Pax6, c-Maf, E-cadherin and alpha-, beta- and gamma-crystallins. Therefore, while signaling by FGF receptors is essential for lens fiber differentiation, different FGF receptors function redundantly.

  12. Colonization of Fiber Cells by Colletotrichum graminicola in Wounded Maize Stalks.

    PubMed

    Venard, C; Vaillancourt, L

    2007-04-01

    ABSTRACT Colonization of wounded maize stalks by a wild-type strain of Colletotrichum graminicola was compared with colonization by a C. graminicola mutant that is avirulent on maize leaves, and by a wild-type strain of C. sublineolum that is normally a pathogen of sorghum but not maize. Local infection by all strains at the wound site resulted in formation of primary lesions consisting of disintegrated parenchyma cells beneath an intact rind and epidermis. However, subsequent rapid longitudinal expansion of the primary lesion occurred only in infections with the wild-type C. graminicola strain, and proceeded specifically through the fiber cells associated with the vascular bundles and the rind. Hyphae emerged from the fiber cells to produce discontinuous secondary lesions. There was no evidence that C. graminicola is a vascular wilt pathogen. Resistance of wounded cv. Jubilee maize stalks to the mutant strain of C. graminicola and to C. sublineolum was associated with restriction of colonization and spread of the pathogen through the fibers, as well as with the limitation of localized destruction of parenchyma cells at the wound site.

  13. Regulation of the muscle fiber microenvironment by activated satellite cells during hypertrophy

    PubMed Central

    Fry, Christopher S.; Lee, Jonah D.; Jackson, Janna R.; Kirby, Tyler J.; Stasko, Shawn A.; Liu, Honglu; Dupont-Versteegden, Esther E.; McCarthy, John J.; Peterson, Charlotte A.

    2014-01-01

    Our aim in the current study was to determine the necessity of satellite cells for long-term muscle growth and maintenance. We utilized a transgenic Pax7-DTA mouse model, allowing for the conditional depletion of > 90% of satellite cells with tamoxifen treatment. Synergist ablation surgery, where removal of synergist muscles places functional overload on the plantaris, was used to stimulate robust hypertrophy. Following 8 wk of overload, satellite cell-depleted muscle demonstrated an accumulation of extracellular matrix (ECM) and fibroblast expansion that resulted in reduced specific force of the plantaris. Although the early growth response was normal, an attenuation of hypertrophy measured by both muscle wet weight and fiber cross-sectional area occurred in satellite cell-depleted muscle. Isolated primary myogenic progenitor cells (MPCs) negatively regulated fibroblast ECM mRNA expression in vitro, suggesting a novel role for activated satellite cells/MPCs in muscle adaptation. These results provide evidence that satellite cells regulate the muscle environment during growth.—Fry, C. S., Lee, J. D., Jackson, J. R., Kirby, T. J., Stasko, S. A., Liu, H., Dupont-Versteegden, E. E., McCarthy, J. J., Peterson, C. A. Regulation of the muscle fiber microenvironment by activated satellite cells during hypertrophy. PMID:24376025

  14. Wnt signaling is required for organization of the lens fiber cell cytoskeleton and development of lens three-dimensional architecture.

    PubMed

    Chen, Yongjuan; Stump, Richard J W; Lovicu, Frank J; Shimono, Akihiko; McAvoy, John W

    2008-12-01

    How an organ develops its characteristic shape is a major issue. This is particularly critical for the eye lens as its function depends on having appropriately ordered three-dimensional cellular architecture. Recent in vitro studies indicate that Wnt signaling plays key roles in regulating morphological events in FGF-induced fiber cell differentiation in the mammalian lens. To further investigate this the Wnt signaling antagonist, secreted frizzled-related protein 2 (Sfrp2), was overexpressed in lens fiber cells of transgenic mice. In these mice fiber cell elongation was attenuated and individual fibers exhibited irregular shapes and consequently did not align or pack regularly; microtubules, microfilaments and intermediate filaments were clearly disordered in these fibers. Furthermore, a striking feature of transgenic lenses was that fibers did not develop the convex curvature typically seen in normal lenses. This appears to be related to a lack of protrusive processes that are required for directed migratory activity at their apical and basal tips as well as for the formation of interlocking processes along their lateral margins. Components of the Wnt/Planar Cell Polarity (PCP) pathway were downregulated or inhibited. Taken together this supports a role for Wnt/PCP signaling in orchestrating the complex organization and dynamics of the fiber cell cytoskeleton.

  15. Enhancing cell viability with pulsating flow in a hollow fiber bioartificial liver.

    PubMed

    Nguyen, Diem T; Brotherton, John D; Chau, Pao C

    2005-10-01

    A pulsating flow of medium was used to alleviate diffusion and transport limitations in a hollow fiber bioreactor containing a human hepatoblastoma cell line. The strategy is easy to implement but effective. The pulsating flow is introduced by a solenoid pinch valve at the outlet of the bioreactor and regulated by a timing circuit. In a permeability test, the system with pulsating flow had much less membrane fouling as compared to the control, a conventional hollow fiber unit. In hepatocyte culture test runs, the pulsating-flow bioreactor demonstrated the ability to maintain a higher cell viability. Histological sections indicated significantly smaller necrotic regions in the pulsating-flow bioreactor as compared to the conventional unit.

  16. In situ pressure calibration for piston cylinder cells via ruby fluorescence with fiber optics

    SciTech Connect

    Koyama-Nakazawa, Kazuko; Koeda, Masahito; Hedo, Masato; Uwatoko, Yoshiya

    2007-06-15

    A fiber-optic measurement technique is developed for estimating the pressure inside a piston cylinder cell up to {approx}4 GPa, based on the pressure-induced R1 fluorescence line shift of ruby (ruby scale). Ruby scale and a conventional technique (calibration on phase transitions of bismuth) were simultaneously applied to the cell filled with a pressure transmitting medium of isopropyl alcohol. The pressure readings of the two methods were consistent with each other, and no pressure gradient was observed. The ruby scale has the advantages of real time estimation and easy installation in a small space. Because of these advantages, three fibers were simultaneously introduced in the sample space at the same time, and pressure distribution was measured for Fluorinert (FC70:FC77=1:1), Daphne oil 7373, and Fomblin oil (YHVAC 130/14)

  17. In situ pressure calibration for piston cylinder cells via ruby fluorescence with fiber optics.

    PubMed

    Koyama-Nakazawa, Kazuko; Koeda, Masahito; Hedo, Masato; Uwatoko, Yoshiya

    2007-06-01

    A fiber-optic measurement technique is developed for estimating the pressure inside a piston cylinder cell up to approximately 4 GPa, based on the pressure-induced R1 fluorescence line shift of ruby (ruby scale). Ruby scale and a conventional technique (calibration on phase transitions of bismuth) were simultaneously applied to the cell filled with a pressure transmitting medium of isopropyl alcohol. The pressure readings of the two methods were consistent with each other, and no pressure gradient was observed. The ruby scale has the advantages of real time estimation and easy installation in a small space. Because of these advantages, three fibers were simultaneously introduced in the sample space at the same time, and pressure distribution was measured for Fluorinert (FC70:FC77=1:1), Daphne oil 7373, and Fomblin oil (YHVAC 13014).

  18. Myosin phosphorylation on stress fibers predicts contact guidance behavior across diverse breast cancer cells.

    PubMed

    Wang, Juan; Schneider, Ian C

    2017-03-01

    During cancer progression the extracellular matrix is remodeled, forming aligned collagen fibers that proceed radially from the tumor, resulting in invasion. We have recently shown that different invasive breast cancer cells respond to epitaxially grown, aligned collagen fibrils differently. This article develops insight into why these cells differ in their contact guidance fidelity. Small changes in contractility or adhesion dramatically alter directional persistence on aligned collagen fibrils, while migration speed remains constant. The directionality of highly contractile and adhesive MDA-MB-231 cells can be diminished by inhibiting Rho kinase or β1 integrin binding. Inversely, the directionality of less contractile and adhesive MTLn3 cells can be enhanced by activating contractility or integrins. Subtle, but quantifiable alterations in myosin II regulatory light chain phosphorylation on stress fibers explain the tuning of contact guidance fidelity, separate from migration per se indicating that the contractile and adhesive state of the cell in combination with collagen organization in the tumor microenvironment determine the efficiency of migration. Understanding how distinct cells respond to contact guidance cues will not only illuminate mechanisms for cancer invasion, but will also allow for the design of environments to separate specific subpopulations of cells from patient-derived tissues by leveraging differences in responses to directional migration cues.

  19. Succinic acid production by Actinobacillus succinogenes using hydrolysates of spent yeast cells and corn fiber.

    PubMed

    Chen, Ke-Quan; Li, Jian; Ma, Jiang-Feng; Jiang, Min; Wei, Ping; Liu, Zhong-Min; Ying, Han-Jie

    2011-01-01

    The enzymatic hydrolysate of spent yeast cells was evaluated as a nitrogen source for succinic acid production by Actinobacillus succinogenes NJ113, using corn fiber hydrolysate as a carbon source. When spent yeast cell hydrolysate was used directly as a nitrogen source, a maximum succinic acid concentration of 35.5 g/l was obtained from a glucose concentration of 50 g/l, with a glucose utilization of 95.2%. Supplementation with individual vitamins showed that biotin was the most likely factor to be limiting for succinic acid production with spent yeast cell hydrolysate. After supplementing spent yeast cell hydrolysate and 90 g/l of glucose with 150 μg/l of biotin, cell growth increased 32.5%, glucose utilization increased 37.6%, and succinic acid concentration was enhanced 49.0%. As a result, when biotin-supplemented spent yeast cell hydrolysate was used with corn fiber hydrolysate, a succinic acid yield of 67.7% was obtained from 70.3 g/l of total sugar concentration, with a productivity of 0.63 g/(l h). Our results suggest that biotin-supplemented spent yeast cell hydrolysate may be an alternative nitrogen source for the efficient production of succinic acid by A. succinogenes NJ113, using renewable resources.

  20. A direct borohydride fuel cell with a polymer fiber membrane and non-noble metal catalysts

    PubMed Central

    Yang, Xiaodong; Liu, Yongning; Li, Sai; Wei, Xiaozhu; Wang, Li; Chen, Yuanzhen

    2012-01-01

    Polymer electrolyte membranes (PEM) and Pt-based catalysts are two crucial components which determine the properties and price of fuel cells. Even though, PEM faces problem of fuel crossover in liquid fuel cells such as direct methanol fuel cell (DMFC) and direct borohydride fuel cell (DBFC), which lowers power output greatly. Here, we report a DBFC in which a polymer fiber membrane (PFM) was used, and metal oxides, such as LaNiO3 and MnO2, were used as cathode catalysts, meanwhile CoO was used as anode catalyst. Peak power density of 663 mW·cm−2 has been achieved at 65°C, which increases by a factor of 1.7–3.7 compared with classic DBFCs. This fuel cell structure can also be extended to other liquid fuel cells, such as DMFC. PMID:22880160

  1. A direct borohydride fuel cell with a polymer fiber membrane and non-noble metal catalysts.

    PubMed

    Yang, Xiaodong; Liu, Yongning; Li, Sai; Wei, Xiaozhu; Wang, Li; Chen, Yuanzhen

    2012-01-01

    Polymer electrolyte membranes (PEM) and Pt-based catalysts are two crucial components which determine the properties and price of fuel cells. Even though, PEM faces problem of fuel crossover in liquid fuel cells such as direct methanol fuel cell (DMFC) and direct borohydride fuel cell (DBFC), which lowers power output greatly. Here, we report a DBFC in which a polymer fiber membrane (PFM) was used, and metal oxides, such as LaNiO₃ and MnO₂, were used as cathode catalysts, meanwhile CoO was used as anode catalyst. Peak power density of 663 mW·cm⁻² has been achieved at 65°C, which increases by a factor of 1.7-3.7 compared with classic DBFCs. This fuel cell structure can also be extended to other liquid fuel cells, such as DMFC.

  2. Fiber and fabric solar cells by directly weaving carbon nanotube yarns with CdSe nanowire-based electrodes.

    PubMed

    Zhang, Luhui; Shi, Enzheng; Ji, Chunyan; Li, Zhen; Li, Peixu; Shang, Yuanyuan; Li, Yibin; Wei, Jinquan; Wang, Kunlin; Zhu, Hongwei; Wu, Dehai; Cao, Anyuan

    2012-08-21

    Electrode materials are key components for fiber solar cells, and when combined with active layers (for light absorption and charge generation) in appropriate ways, they enable design and fabrication of efficient and innovative device structures. Here, we apply carbon nanotube yarns as counter electrodes in combination with CdSe nanowire-grafted primary electrodes (Ti wire) for making fiber and fabric-shaped photoelectrochemical cells with power conversion efficiencies in the range 1% to 2.9%. The spun-twist long nanotube yarns possess both good electrical conductivity and mechanical flexibility compared to conventional metal wires or carbon fibers, which facilitate fabrication of solar cells with versatile configurations. A unique feature of our process is that instead of making individual fiber cells, we directly weave single or multiple nanotube yarns with primary electrodes into a functional fabric. Our results demonstrate promising applications of semiconducting nanowires and carbon nanotubes in woven photovoltaics.

  3. Material Properties and Osteogenic Differentiation of Marrow Stromal Cells on Fiber-Reinforced Laminated Hydrogel Nanocomposites

    PubMed Central

    Xu, Weijie; Ma, Junyu; Jabbari, Esmaiel

    2009-01-01

    The fibrils in the bone matrix are glued together by ECM proteins to form laminated structures (osteons) to provide elasticity and a supportive substrate for osteogenesis. The objective of this work was to investigate material properties and osteogenic differentiation of bone marrow stromal (BMS) cells seeded on osteon-mimetic fiber-reinforced hydrogel/apatite composites. Layers of electrospun poly(L-lactide) (L-PLA) fiber mesh coated with a poly(lactide-co-ethylene oxide fumarate) (PLEOF) hydrogel precursor solution were stacked and pressed together, and crosslinked to produce a laminated fiber-reinforced composite. Hydroxyapatite (HA) nanocrystals were added to the precursor solution to produce an osteoconductive matrix for BMS cells. Acrylamide-terminated RGD peptide (Ac-GRGD) was conjugated to the PLEOF/HA hydrogel phase to promote focal point adhesion of BMS cells. Laminates were characterized with respect to Young’s modulus, degradation kinetics, and osteogenic differentiation of BMS cells. The moduli of the laminates under dry and wet conditions were significantly higher than those of the fiber mesh and PLEOF/HA hydrogel, and within the range of values reported for wet human cancellous bone. At days 14 and 21, ALPase activity of the laminates was significantly higher than those of the fiber mesh and hydrogel. Lamination significantly increased the extent of mineralization of BMS cells and laminates with HA and conjugated with RGD (Lam-RGD-HA) had 2.7-, 3.5-, and 2.8-fold higher calcium content (compared to laminates without HA or RGD) after 7, 14, and 21 days, respectively. The Lam-RGD-HA group had significantly higher expression of osteopontin (OP) and osteocalcin (OC) compared to the hydrogel or laminates without HA or RGD, consistent with the higher ALPase activity and calcium content of Lam-RGD-HA. Laminated osteon-mimetic structures have the potential to provide mechanical strength to the regenerating region as well as supporting the differentiation

  4. Fiber and fabric solar cells by directly weaving carbon nanotube yarns with CdSe nanowire-based electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Luhui; Shi, Enzheng; Ji, Chunyan; Li, Zhen; Li, Peixu; Shang, Yuanyuan; Li, Yibin; Wei, Jinquan; Wang, Kunlin; Zhu, Hongwei; Wu, Dehai; Cao, Anyuan

    2012-07-01

    Electrode materials are key components for fiber solar cells, and when combined with active layers (for light absorption and charge generation) in appropriate ways, they enable design and fabrication of efficient and innovative device structures. Here, we apply carbon nanotube yarns as counter electrodes in combination with CdSe nanowire-grafted primary electrodes (Ti wire) for making fiber and fabric-shaped photoelectrochemical cells with power conversion efficiencies in the range 1% to 2.9%. The spun-twist long nanotube yarns possess both good electrical conductivity and mechanical flexibility compared to conventional metal wires or carbon fibers, which facilitate fabrication of solar cells with versatile configurations. A unique feature of our process is that instead of making individual fiber cells, we directly weave single or multiple nanotube yarns with primary electrodes into a functional fabric. Our results demonstrate promising applications of semiconducting nanowires and carbon nanotubes in woven photovoltaics.Electrode materials are key components for fiber solar cells, and when combined with active layers (for light absorption and charge generation) in appropriate ways, they enable design and fabrication of efficient and innovative device structures. Here, we apply carbon nanotube yarns as counter electrodes in combination with CdSe nanowire-grafted primary electrodes (Ti wire) for making fiber and fabric-shaped photoelectrochemical cells with power conversion efficiencies in the range 1% to 2.9%. The spun-twist long nanotube yarns possess both good electrical conductivity and mechanical flexibility compared to conventional metal wires or carbon fibers, which facilitate fabrication of solar cells with versatile configurations. A unique feature of our process is that instead of making individual fiber cells, we directly weave single or multiple nanotube yarns with primary electrodes into a functional fabric. Our results demonstrate promising applications

  5. Increased curvature of hollow fiber membranes could up-regulate differential functions of renal tubular cell layers.

    PubMed

    Shen, Chong; Meng, Qin; Zhang, Guoliang

    2013-08-01

    Tissue engineering devices as in vitro cell culture systems in scaffolds has encountered the bottleneck due to their much lower cell functions than real tissues/organs in vivo. Such situation has been improved in some extent by mimicking the cell microenvironments in vivo from either chemical or physical ways. However, microenvironmental curvature, commonly seen in real tissues/organs, has never been manipulated to regulate the cell performance in vitro. In this regard, this paper fabricated polysulfone membranes with or without polyethylene glycol modification to investigate the impact of curvature on two renal tubular cells. Regardless the varying membrane curvatures among hollow fiber membranes of different diameters and flat membrane of zero curvature, both renal cells could well attach at 4 h of seeding and form similar confluent layers at 6 days on each membrane. Nevertheless, the renal cells on hollow fibers, though showing confluent morphology as those on flat membranes, expressed higher renal functions and, moreover, the renal functions significantly increased with the membrane curvature among hollow fibers. Such upregulation on functions was unassociated with mass transport barrier of hollow fibers, because the cultures on lengthwise cut hollow fibers without mass transfer barrier showed same curvature effect on renal functions as whole hollow fibers. It could be proposed that the curvature of hollow fiber membrane approaching to the large curvature in kidney tubules increased the mechanical stress in the renal cells and thus might up-regulate the renal cell functions. In conclusion, the increase of substrate curvature could up-regulate the cell functions without altering the confluent cell morphology and this finding will facilitate the design of functional tissue engineering devices.

  6. Rac1 GTPase-deficient mouse lens exhibits defects in shape, suture formation, fiber cell migration and survival.

    PubMed

    Maddala, Rupalatha; Chauhan, Bharesh K; Walker, Christopher; Zheng, Yi; Robinson, Michael L; Lang, Richard A; Rao, Ponugoti V

    2011-12-01

    Morphogenesis and shape of the ocular lens depend on epithelial cell elongation and differentiation into fiber cells, followed by the symmetric and compact organization of fiber cells within an enclosed extracellular matrix-enriched elastic capsule. The cellular mechanisms orchestrating these different events however, remain obscure. We investigated the role of the Rac1 GTPase in these processes by targeted deletion of expression using the conditional gene knockout (cKO) approach. Rac1 cKO mice were derived from two different Cre (Le-Cre and MLR-10) transgenic mice in which lens-specific Cre expression starts at embryonic day 8.75 and 10.5, respectively, in both the lens epithelium and fiber cells. The Le-Cre/Rac1 cKO mice exhibited an early-onset (E12.5) and severe lens phenotype compared to the MLR-10/Rac1 cKO (E15.5) mice. While the Le-Cre/Rac1 cKO lenses displayed delayed primary fiber cell elongation, lenses from both Rac1 cKO strains were characterized by abnormal shape, impaired secondary fiber cell migration, sutural defects and thinning of the posterior capsule which often led to rupture. Lens fiber cell N-cadherin/β-catenin/Rap1/Nectin-based cell-cell junction formation and WAVE-2/Abi-2/Nap1-regulated actin polymerization were impaired in the Rac1 deficient mice. Additionally, the Rac1 cKO lenses were characterized by a shortened epithelial sheet, reduced levels of extracellular matrix (ECM) proteins and increased apoptosis. Taken together, these data uncover the essential role of Rac1 GTPase activity in establishment and maintenance of lens shape, suture formation and capsule integrity, and in fiber cell migration, adhesion and survival, via regulation of actin cytoskeletal dynamics, cell adhesive interactions and ECM turnover.

  7. Rac1 GTPase -deficient mouse lens exhibits defects in shape, suture formation, fiber cell migration and survival

    PubMed Central

    Maddala, Rupalatha; Chauhan, Bharesh K.; Walker, Christopher; Zheng, Yi; Robinson, Michael L.; Lang, Richard A.; Rao, Ponugoti V.

    2011-01-01

    Morphogenesis and shape of the ocular lens depend on epithelial cell elongation and differentiation into fiber cells, followed by the symmetric and compact organization of fiber cells within an enclosed extracellular matrix-enriched elastic capsule. The cellular mechanisms orchestrating these different events however, remain obscure. We investigated the role of the Rac1 GTPase in these processes by targeted deletion of expression using the conditional gene knockout (cKO) approach. Rac1 cKO mice were derived from two different Cre (Le-Cre and MLR-10) transgenic mice in which lens-specific Cre expression starts at embryonic day 8.75 and 10.5, respectively, in both the lens epithelium and fiber cells. The Le-Cre/Rac1 cKO mice exhibited an early-onset (E12.5) and severe lens phenotype compared to the MLR-10/Rac1 cKO (E15.5) mice. While the Le-Cre/Rac1 cKO lenses displayed delayed primary fiber cell elongation, lenses from both Rac1 cKO strains were characterized by abnormal shape, impaired secondary fiber cell migration, sutural defects and thinning of the posterior capsule which often led to rupture. Lens fiber cell N-cadherin/β-catenin/Rap1/Nectin-based cell-cell junction formation and WAVE-2/Abi-2/Nap1-regulated actin polymerization were impaired in the Rac1 deficient mice. Additionally, the Rac1 cKO lenses were characterized by a shortened epithelial sheet, reduced levels of extracellular matrix (ECM) proteins and increased apoptosis. Taken together, these data uncover the essential role of Rac1 GTPase activity in establishment and maintenance of lens shape, suture formation and capsule integrity, and in fiber cell migration, adhesion and survival, via regulation of actin cytoskeletal dynamics, cell adhesive interactions and ECM turnover. PMID:21945075

  8. Proliferation and differentiation of mesenchymal stem cell on collagen sponge reinforced with polypropylene/polyethylene terephthalate blend fibers.

    PubMed

    Mohajeri, Sara; Hosseinkhani, Hossein; Ebrahimi, Nadereh Golshan; Nikfarjam, Laleh; Soleimani, Masoud; Kajbafzadeh, Abdol-Mohammad

    2010-12-01

    Although tissue-engineered scaffolds made from collagen sponge are suitable for cell infiltrating, easily supplying oxygen and nutrients to cells, and removing the waste products, their mechanical properties are not satisfactory to be used as scaffold materials for tissue engineering applications. To improve mechanical properties of collagen, a novel porous scaffold for bone tissue engineering was prepared with collagen sponge reinforced by polypropylene/polyethylene terephthalate (PP/PET) fibers. Collagen solution (6.33 mg/mL) with PP/PET fibers (collagen/fiber ratio [w/w]: 1.27, 0.63, 0.42, 0.25) was freeze-dried, followed by cross-linking of combined dehydrothermal and glutaraldehyde. A scanning electron microscopy-based analysis of surface of the sponges demonstrated that the sponge with collagen/fiber <0.25 exhibited homogenous and interconnected pore structure with an average pore size of 200 μm. Incorporation of PP/PET fibers significantly enhanced the compressive strength of the collagen sponge. Proliferation and osteogenic differentiation of mesenchymal stem cell in collagen sponges reinforced with PP/PET fibers incorporation were significantly enhanced compared with collagen sponge without PP/PET incorporation. We conclude that incorporation of PP/PET fibers not only improves the mechanical properties of collagen sponge, but also enables mesenchymal stem cells to positively improve their proliferation and differentiation.

  9. Influence of brain-derived neurotrophic factor on pathfinding of dentate granule cell axons, the hippocampal mossy fibers.

    PubMed

    Tamura, Makoto; Tamura, Naohiro; Ikeda, Takamitsu; Koyama, Ryuta; Ikegaya, Yuji; Matsuki, Norio; Yamada, Maki K

    2009-01-31

    Mossy fibers, the dentate granule cell axons, are generated throughout an animal's lifetime. Mossy fiber paths and synapses are primarily restricted to the stratum lucidum within the CA3 region. Brain-derived neurotrophic factor (BDNF), a neurotrophin family protein that activates Trk neurotrophin receptors, is highly expressed in the stratum lucidum in an activity-dependent manner. The addition of a Trk neurotrophin receptor inhibitor, K252a, to cultured hippocampal slices induced aberrant extension of mossy fibers into ectopic regions. BDNF overexpression in granule cells ameliorated the mossy fiber pathway abnormalities caused by a submaximal dose of K252a. A similar rescue was observed when BDNF was expressed in CA3 pyramidal cells, most notably in mossy fibers distal to the expression site. These findings are the first to clarify the role of BDNF in mossy fiber pathfinding, not as an attractant cue but as a regulator, possibly acting in a paracrine manner. This effect of BDNF may be as a signal for new fibers to fasciculate and extend further to form synapses with neurons that are far from active BDNF-expressing synapses. This mechanism would ensure the emergence of new independent dentate gyrus-CA3 circuits by the axons of new-born granule cells.

  10. Expansion of activated lymphocytes obtained from renal cell carcinoma in an automated hollow fiber bioreactor.

    PubMed

    Hillman, G G; Wolf, M L; Montecillo, E; Younes, E; Ali, E; Pontes, J E; Haas, G P

    1994-01-01

    Immunotherapy using IL-2 alone or combined with activated lymphocytes has been promising for metastatic renal cell carcinoma. Cytotoxic lymphocytes can be isolated from tumors, expanded in vitro with IL-2, and adoptively transferred back into the tumor-bearing host. These cells can also be transduced with the genes coding for cytokines for local delivery to tumor sites. A major drawback in adoptive immunotherapy is the cumbersome and expensive culture technology associated with the growth of large numbers of cells required for their therapeutic effect. To reduce the cost, resources, and manpower, we have developed the methodology for lymphocyte activation and expansion in the automated hollow fiber bioreactor IMMUNO*STAR Cell Expander (ACT BIOMEDICAL, INC). Tumor Infiltrating Lymphocytes (TIL) isolated from human renal cell carcinoma tumor specimens were inoculated at a number of 10(8) cells in a small bioreactor of 30 ml extracapillary space volume. We have determined the medium flow rates and culture conditions to obtain a significant and repeated expansion of TIL at weekly intervals. The lymphocytes cultured in the bioreactor demonstrated the same phenotype and cytotoxic activity as those expanded in parallel in tissue culture plates. Lymphocyte expansion in the hollow fiber bioreactor required lower volumes of medium, human serum, IL-2 and minimal labor. This technology may facilitate the use of adoptive immunotherapy for the treatment of refractory malignancies.

  11. Efficient delivery of human single fiber-derived muscle precursor cells via biocompatible scaffold.

    PubMed

    Boldrin, Luisa; Malerba, Alberto; Vitiello, Libero; Cimetta, Elisa; Piccoli, Martina; Messina, Chiara; Gamba, Pier Giorgio; Elvassore, Nicola; De Coppi, Paolo

    2008-01-01

    The success of cell therapy for skeletal muscle disorders depends upon two main factors: the cell source and the method of delivery. In this work we have explored the therapeutic potential of human muscle precursor cells (hMPCs), obtained from single human muscle fibers, implanted in vivo via micropatterned scaffolds. hMPCs were initially expanded and characterized in vitro by immunostaining and flow cytometric analysis. For in vivo studies, hMPCs were seeded onto micropatterned poly-lactic-glycolic acid 3D-scaffolds fabricated using soft-lithography and thermal membrane lamination. Seeded scaffolds were then implanted in predamaged tibialis anterior muscles of CD1 nude mice; hMPCs were also directly injected in contralateral limbs as controls. Similarly to what we previously described with mouse precursors cells, we found that hMPCs were able to participate in muscle regeneration and scaffold-implanted muscles contained a greater number of human nuclei, as revealed by immunostaining and Western blot analyses. These results indicate that hMPCs derived from single fibers could be a good and reliable cell source for the design of therapeutic protocols and that implantation of cellularized scaffolds is superior to direct injection for the delivery of myogenic cells into regenerating skeletal muscle.

  12. Induced pluripotent stem cell-derived hepatocytes and endothelial cells in multi-component hydrogel fibers for liver tissue engineering.

    PubMed

    Du, Chan; Narayanan, Karthikeyan; Leong, Meng Fatt; Wan, Andrew C A

    2014-07-01

    Liver tissue engineering requires a suitable cell source, methodologies to assemble the cells within their niche microenvironments in a spatially defined manner, and vascularization of the construct in vivo for maintenance of hepatocyte viability and function. Recently, we have developed methods of encapsulating cells within separate domains in multi-component hydrogel fibers and methods of assembling fibers to form 3D-patterned tissue constructs. In the present work, we have combined these approaches to encapsulate hepatocytes and endothelial cells within their specific niches, and to assemble them into endothelialized liver tissue constructs. The hepatocytes and endothelial cells were obtained in parallel by differentiating human recombinant protein-induced human pluripotent stem cells, resulting in a construct which contained genetically identical endothelial and parenchymal elements. We were able to demonstrate that the presence of endothelial cells in the scaffold significantly improved hepatocyte function in vitro and facilitated vascularization of the scaffold when implanted in a mouse partial hepatectomy model. The in vivo studies further asserted that integration of the scaffold with host vasculature had occurred, as demonstrated by the presence of human albumin in the mouse serum. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Tropomodulin 1 Regulation of Actin Is Required for the Formation of Large Paddle Protrusions Between Mature Lens Fiber Cells

    PubMed Central

    Cheng, Catherine; Nowak, Roberta B.; Biswas, Sondip K.; Lo, Woo-Kuen; FitzGerald, Paul G.; Fowler, Velia M.

    2016-01-01

    Purpose To elucidate the proteins required for specialized small interlocking protrusions and large paddle domains at lens fiber cell tricellular junctions (vertices), we developed a novel method to immunostain single lens fibers and studied changes in cell morphology due to loss of tropomodulin 1 (Tmod1), an F-actin pointed end–capping protein. Methods We investigated F-actin and F-actin–binding protein localization in interdigitations of Tmod1+/+ and Tmod1−/− single mature lens fibers. Results F-actin–rich small protrusions and large paddles were present along cell vertices of Tmod1+/+ mature fibers. In contrast, Tmod1−/− mature fiber cells lack normal paddle domains, while small protrusions were unaffected. In Tmod1+/+ mature fibers, Tmod1, β2-spectrin, and α-actinin are localized in large puncta in valleys between paddles; but in Tmod1−/− mature fibers, β2-spectrin was dispersed while α-actinin was redistributed at the base of small protrusions and rudimentary paddles. Fimbrin and Arp3 (actin-related protein 3) were located in puncta at the base of small protrusions, while N-cadherin and ezrin outlined the cell membrane in both Tmod1+/+ and Tmod1−/− mature fibers. Conclusions These results suggest that distinct F-actin organizations are present in small protrusions versus large paddles. Formation and/or maintenance of large paddle domains depends on a β2-spectrin–actin network stabilized by Tmod1. α-Actinin–crosslinked F-actin bundles are enhanced in absence of Tmod1, indicating altered cytoskeleton organization. Formation of small protrusions is likely facilitated by Arp3-branched and fimbrin-bundled F-actin networks, which do not depend on Tmod1. This is the first work to reveal the F-actin–associated proteins required for the formation of paddles between lens fibers. PMID:27537257

  14. Tropomodulin 1 Regulation of Actin Is Required for the Formation of Large Paddle Protrusions Between Mature Lens Fiber Cells.

    PubMed

    Cheng, Catherine; Nowak, Roberta B; Biswas, Sondip K; Lo, Woo-Kuen; FitzGerald, Paul G; Fowler, Velia M

    2016-08-01

    To elucidate the proteins required for specialized small interlocking protrusions and large paddle domains at lens fiber cell tricellular junctions (vertices), we developed a novel method to immunostain single lens fibers and studied changes in cell morphology due to loss of tropomodulin 1 (Tmod1), an F-actin pointed end-capping protein. We investigated F-actin and F-actin-binding protein localization in interdigitations of Tmod1+/+ and Tmod1-/- single mature lens fibers. F-actin-rich small protrusions and large paddles were present along cell vertices of Tmod1+/+ mature fibers. In contrast, Tmod1-/- mature fiber cells lack normal paddle domains, while small protrusions were unaffected. In Tmod1+/+ mature fibers, Tmod1, β2-spectrin, and α-actinin are localized in large puncta in valleys between paddles; but in Tmod1-/- mature fibers, β2-spectrin was dispersed while α-actinin was redistributed at the base of small protrusions and rudimentary paddles. Fimbrin and Arp3 (actin-related protein 3) were located in puncta at the base of small protrusions, while N-cadherin and ezrin outlined the cell membrane in both Tmod1+/+ and Tmod1-/- mature fibers. These results suggest that distinct F-actin organizations are present in small protrusions versus large paddles. Formation and/or maintenance of large paddle domains depends on a β2-spectrin-actin network stabilized by Tmod1. α-Actinin-crosslinked F-actin bundles are enhanced in absence of Tmod1, indicating altered cytoskeleton organization. Formation of small protrusions is likely facilitated by Arp3-branched and fimbrin-bundled F-actin networks, which do not depend on Tmod1. This is the first work to reveal the F-actin-associated proteins required for the formation of paddles between lens fibers.

  15. Hollow core photonic crystal fiber for monitoring leukemia cells using surface enhanced Raman scattering (SERS)

    PubMed Central

    Khetani, Altaf; Momenpour, Ali; Alarcon, Emilio I.; Anis, Hanan

    2015-01-01

    The present paper demonstrates an antibody-free, robust, fast, and portable platform for detection of leukemia cells using Raman spectroscopy with a 785-nm laser diode coupled to a hollow core photonic crystal (HC-PCF) containing silver nanoparticles. Acute myeloid leukemia is one of the most common bone marrow cancers in children and youths. Clinical studies suggest that early diagnosis and remission evaluation of myoblasts in the bone marrow are pivotal for improving patient survival. However, the current protocols for leukemic cells detection involve the use of expensive antibodies and flow cytometers. Thus, we have developed a new technology for detection of leukemia cells up to 300 cells/ml using a compact fiber HC-PCF, which offers a novel alternative to existing clinical standards. Furthermore, we were also able to accurately distinguish live, apoptotic and necrotic leukemic cells. PMID:26601021

  16. Hollow core photonic crystal fiber for monitoring leukemia cells using surface enhanced Raman scattering (SERS).

    PubMed

    Khetani, Altaf; Momenpour, Ali; Alarcon, Emilio I; Anis, Hanan

    2015-11-01

    The present paper demonstrates an antibody-free, robust, fast, and portable platform for detection of leukemia cells using Raman spectroscopy with a 785-nm laser diode coupled to a hollow core photonic crystal (HC-PCF) containing silver nanoparticles. Acute myeloid leukemia is one of the most common bone marrow cancers in children and youths. Clinical studies suggest that early diagnosis and remission evaluation of myoblasts in the bone marrow are pivotal for improving patient survival. However, the current protocols for leukemic cells detection involve the use of expensive antibodies and flow cytometers. Thus, we have developed a new technology for detection of leukemia cells up to 300 cells/ml using a compact fiber HC-PCF, which offers a novel alternative to existing clinical standards. Furthermore, we were also able to accurately distinguish live, apoptotic and necrotic leukemic cells.

  17. Columnar deformation of human red blood cell by highly localized fiber optic Bessel beam stretcher

    PubMed Central

    Lee, Sungrae; Joo, Boram; Jeon, Pyo Jin; Im, Seongil; Oh, Kyunghwan

    2015-01-01

    A single human red blood cell was optically stretched along two counter-propagating fiber-optic Bessel-like beams in an integrated lab-on-a-chip structure. The beam enabled highly localized stretching of RBC, and it induced a nonlinear mechanical deformation to finally reach an irreversible columnar shape that has not been reported. We characterized and systematically quantified this optically induced mechanical deformation by the geometrical aspect ratio of stretched RBC and the irreversible stretching time. The proposed RBC mechanism can realize a versatile and compact opto-mechanical platform for optical diagnosis of biological substances in the single cell level. PMID:26601005

  18. Taste cell responses in the frog are modulated by parasympathetic efferent nerve fibers.

    PubMed

    Sato, Toshihide; Okada, Yukio; Miyazaki, Toshihiro; Kato, Yuzo; Toda, Kazuo

    2005-11-01

    We studied the anatomical properties of parasympathetic postganglionic neurons in the frog tongue and their modulatory effects on taste cell responses. Most of the parasympathetic ganglion cell bodies in the tongue were found in extremely small nerve bundles running near the fungiform papillae, which originate from the lingual branches of the glossopharyngeal (GP) nerve. The density of parasympathetic postganglionic neurons in the tongue was 8000-11,000/mm(3) of the extremely small nerve bundle. The mean major axis of parasympathetic ganglion cell bodies was 21 microm, and the mean length of parasympathetic postganglionic neurons was 1.45 mm. Electrical stimulation at 30 Hz of either the GP nerve or the papillary nerve produced slow hyperpolarizing potentials (HPs) in taste cells. After nicotinic acetyl choline receptors on the parasympathetic ganglion cells in the tongue had been blocked by intravenous (i.v.) injection of D-tubocurarine (1 mg/kg), stimulation of the GP nerve did not induce any slow HPs in taste cells but that of the papillary nerve did. A further i.v. injection of a substance P NK-1 antagonist, L-703,606, blocked the slow HPs induced by the papillary nerve stimulation. This suggests that the parasympathetic postganglionic efferent fibers innervate taste cells and are related to a generation of the slow HPs and that substance P is released from the parasympathetic postganglionic axon terminals. When the resting membrane potential of a taste cell was hyperpolarized by a prolonged slow HP, the gustatory receptor potentials for NaCl and sugar stimuli were enhanced in amplitude, but those for quinine-HCl and acetic acid stimuli remained unchanged. It is concluded that frog taste cell responses are modulated by activities of parasympathetic postganglionic efferent fibers innervating these cells.

  19. Degradable phosphate glass fiber reinforced polymer matrices: mechanical properties and cell response.

    PubMed

    Brauer, Delia S; Rüssel, Christian; Vogt, Sebastian; Weisser, Jürgen; Schnabelrauch, Matthias

    2008-01-01

    The development of biodegradable materials for internal fracture fixation is of great interest, as they would both eliminate the problem of stress shielding and obviate the need for a second operation to remove fixation devices. Preliminary investigations for the production of degradable fiber reinforced polymer composite materials are detailed. Composites were produced of phosphate invert glass fibers of the glass system P(2)O(5)-CaO-MgO-Na(2)O-TiO(2), which showed a low solubility in previous work. The fibers were embedded into a matrix of a degradable organic polymer network based on methacrylate-modified oligolactide. Fracture behavior, bending strength and elastic modulus were evaluated during 3-point bending tests and the fracture surface of the composites was investigated using a scanning electron microscope. Short-term biocompatibility was tested in an FDA/EtBr viability assay using MC3T3-E1 murine pre-osteoblast cells and showed a good cell compatibility of the composite materials. Results suggested that these composite materials are biocompatible and show mechanical properties which are of interest for the production of degradable bone fixation devices.

  20. Demonstration of actin filament stress fibers in microvascular endothelial cells in situ.

    PubMed

    Nehls, V; Drenckhahn, D

    1991-07-01

    We have developed a method for immunostaining the microvascular tree of rat mesenteric windows in situ. The procedure consists of three steps, i.e., mild fixation with formaldehyde, controlled proteolytic digestion of the mesothelial layer, and permeabilization with acetone. Discrimination between different microvascular segments was possible by double-fluorescent staining with antibodies to the smooth muscle isoform of alpha-actin and to nonmuscle myosin from platelets. Antibodies to nonmuscle myosin labeled numerous longitudinally oriented cables in endothelial cells of all microvascular segments (arterioles, metarterioles, pre-, mid-, and postcapillaries, small venules). Occasionally, the myosin-containing cables displayed the interrupted sarcomere-like staining pattern that is diagnostic for stress fibers. In contrast, staining of actin filaments with phalloidin-rhodamin resulted in a noninterrupted, continuous fluorescence of the stress fibers. A possible functional role of microvascular endothelial stress fibers is to serve as a tensile cytoskeletal scaffold that stabilizes the tubular, three-dimensional geometry of microvessels and, in addition, to help the endothelium resist the shear forces created by blood flow and by collision with red and white blood cells.

  1. A novel multi-coaxial hollow fiber bioreactor for adherent cell types. Part 1: hydrodynamic studies.

    PubMed

    Wolfe, Stephen P; Hsu, Edward; Reid, Lola M; Macdonald, Jeffrey M

    2002-01-05

    A novel multi-coaxial bioreactor for three-dimensional cultures of adherent cell types, such as liver, is described. It is composed of four tubes of increasing diameter placed one inside the other, creating four spatially isolated compartments. Liver acinar structure and physiological parameters are mimicked by sandwiching cells in the space between the two innermost semi-permeable tubes, or hollows fibers, and creating a radial flow of media from an outer compartment (ECC), through the cell mass compartment, and to an inner compartment (ICC). The outermost compartment is created by gas-permeable tubing, and the housing is used to oxygenate the perfusion media to periportal levels in the ECC. Experiments were performed using distilled water to correlate the radial flow rate (Q(r)) with (1) the pressure drop (DeltaP) between the media compartments that sandwich the cell compartment and (2) the pressure in the cell compartment (P(c)). These results were compared with the theoretical profile calculated based on the hydraulic permeability of the two innermost fibers. Phase-contrast velocity-encoded magnetic resonance imaging was used to visualize directly the axial velocities inside the bioreactor and confirm the assumptions of laminar flow and zero axial velocity at the boundaries of each compartment in the bioreactor. Axial flow rates were calculated from the magnetic resonance imaging results and were similar to the measured axial flow rates for the previously described experiments.

  2. Loss of LAP2 alpha delays satellite cell differentiation and affects postnatal fiber-type determination.

    PubMed

    Gotic, Ivana; Schmidt, Wolfgang M; Biadasiewicz, Katarzyna; Leschnik, Michael; Spilka, Rita; Braun, Juliane; Stewart, Colin L; Foisner, Roland

    2010-03-31

    Lamina-associated polypeptide 2 alpha (LAP2 alpha) is a nucleoplasmic protein implicated in cell cycle regulation through its interaction with A-type lamins and the retinoblastoma protein. Mutations in lamin A/C and LAP2 alpha cause late onset striated muscle diseases, but the molecular mechanisms are poorly understood. To study the role of LAP2 alpha in skeletal muscle function and postnatal tissue homeostasis, we generated complete and muscle-specific LAP2 alpha knockout mice. Whereas overall muscle morphology, function, and regeneration were not detectably affected, the myofiber-associated muscle stem cell pool was increased in complete LAP2 alpha knockout animals. At molecular level, the absence of LAP2 alpha preserved the stem cell-like phenotype of Lap2 alpha(-/-) primary myoblasts and delayed their in vitro differentiation. In addition, loss of LAP2 alpha shifted the myofiber-type ratios of adult slow muscles toward fast fiber types. Conditional Cre-mediated late muscle-specific ablation of LAP2 alpha affected early stages of in vitro myoblast differentiation, and also fiber-type determination, but did not change myofiber-associated stem cell numbers in vivo. Our data demonstrate multiple and distinct functions of LAP2 alpha in muscle stem cell maintenance, early phases of myogenic differentiation, and muscle remodeling.

  3. Disassembly of the lens fiber cell nucleus to create a clear lens: The p27 descent.

    PubMed

    Rowan, Sheldon; Chang, Min-Lee; Reznikov, Natalie; Taylor, Allen

    2017-03-01

    The eye lens is unique among tissues: it is transparent, does not form tumors, and the majority of its cells degrade their organelles, including their cell nuclei. A mystery for over a century, there has been considerable recent progress in elucidating mechanisms of lens fiber cell denucleation (LFCD). In contrast to the disassembly and reassembly of the cell nucleus during mitosis, LFCD is a unidirectional process that culminates in destruction of the fiber cell nucleus. Whereas p27(Kip1), the cyclin-dependent kinase inhibitor, is upregulated during formation of LFC in the outermost cortex, in the inner cortex, in the nascent organelle free zone, p27(Kip1) is degraded, markedly activating cyclin-dependent kinase 1 (Cdk1). This process results in phosphorylation of nuclear Lamins, dissociation of the nuclear membrane, and entry of lysosomes that liberate DNaseIIβ (DLAD) to cleave chromatin. Multiple cellular pathways, including the ubiquitin proteasome system and the unfolded protein response, converge on post-translational regulation of p27(Kip1). Mutations that impair these pathways are associated with congenital cataracts and loss of LFCD. These findings highlight new regulatory nodes in the lens and suggest that we are close to understanding this fascinating terminal differentiation process. Such knowledge may offer a new means to confront proliferative diseases including cancer. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Asbestos fibers mediate transformation of monkey cells by exogenous plasmid DNA

    SciTech Connect

    Appel, J.D.; Fasy, T.M.; Kohtz, D.S.; Kohtz, J.D.; Johnson, E.M. )

    1988-10-01

    The authors have tested the ability of chrysotile asbestos fibers to introduce plasmid DNA into monkey COS-7 cells and the ability of this DNA to function in both replication and gene expression. Chrysotile fibers are at least as effective as calcium phosphate in standard transfection assays at optimal ratios of asbestos to DNA. After transfection with chrysotile, a minor percentage of introduced plasmid DNA bearing a simian virus 40 origin of replication replicates after 24 hr. Fragmentation of entering DNA is more prominent with asbestos than with calcium phosphate, and after 72 hr most DNA introduced by asbestos is associated with chromosomal DNA. Cells transfected with plasmid p11-4, bearing the p53 protooncogene, express this gene. Cells transfected with pSV2-neo express a gene conferring resistance of antibiotic G418, allowing isolation of colonies of transformed cells after 18 days. The introduction of exogenous DNA into eukaryotic cells could cause mutations in several ways and thus contribute to asbestos-induced oncogenesis.

  5. A mechanical model of actin stress fiber formation and substrate elasticity sensing in adherent cells.

    PubMed

    Walcott, Sam; Sun, Sean X

    2010-04-27

    Tissue cells sense and respond to the stiffness of the surface on which they adhere. Precisely how cells sense surface stiffness remains an open question, though various biochemical pathways are critical for a proper stiffness response. Here, based on a simple mechanochemical model of biological friction, we propose a model for cell mechanosensation as opposed to previous more biochemically based models. Our model of adhesion complexes predicts that these cell-surface interactions provide a viscous drag that increases with the elastic modulus of the surface. The force-velocity relation of myosin II implies that myosin generates greater force when the adhesion complexes slide slowly. Then, using a simple cytoskeleton model, we show that an external force applied to the cytoskeleton causes actin filaments to aggregate and orient parallel to the direction of force application. The greater the external force, the faster this aggregation occurs. As the steady-state probability of forming these bundles reflects a balance between the time scale of bundle formation and destruction (because of actin turnover), more bundles are formed when the cytoskeleton time-scale is small (i.e., on stiff surfaces), in agreement with experiment. As these large bundles of actin, called stress fibers, appear preferentially on stiff surfaces, our mechanical model provides a mechanism for stress fiber formation and stiffness sensing in cells adhered to a compliant surface.

  6. N-myc regulates growth and fiber cell differentiation in lens development

    PubMed Central

    Cavalheiro, Gabriel R.; Matos-Rodrigues, Gabriel E.; Zhao, Yilin; Gomes, Anielle L.; Anand, Deepti; Predes, Danilo; de Lima, Silmara; Abreu, Jose G.; Zheng, Deyou; Lachke, Salil A.; Cvekl, Ales; Martins, Rodrigo A. P.

    2017-01-01

    Myc proto-oncogenes regulate diverse cellular processes during development, but their roles during morphogenesis of specific tissues are not fully understood. We found that c-myc regulates cell proliferation in mouse lens development and previous genome-wide studies suggested functional roles for N-myc in developing lens. Here, we examined the role of N-myc in mouse lens development. Genetic inactivation of N-myc in the surface ectoderm or lens vesicle impaired eye and lens growth, while "late" inactivation in lens fibers had no effect. Unexpectedly, defective growth of N-myc--deficient lenses was not associated with alterations in lens progenitor cell proliferation or survival. Notably, N-myc-deficient lens exhibited a delay in degradation of DNA in terminally differentiating lens fiber cells. RNA-sequencing analysis of N-myc--deficient lenses identified a cohort of down-regulated genes associated with fiber cell differentiation that included DNaseIIβ. Further, an integrated analysis of differentially expressed genes in N-myc-deficient lens using normal lens expression patterns of iSyTE, N-myc-binding motif analysis and molecular interaction data from the String database led to the derivation of an N-myc-based gene regulatory network in the lens. Finally, analysis of N-myc and c-myc double-deficient lens demonstrated that these Myc genes cooperate to drive lens growth prior to lens vesicle stage. Together, these findings provide evidence for exclusive and cooperative functions of Myc transcription factors in mouse lens development and identify novel mechanisms by which N-myc regulates cell differentiation during eye morphogenesis. PMID:28716713

  7. Miniaturized ascorbic acid fuel cells with flexible electrodes made of graphene-coated carbon fiber cloth

    NASA Astrophysics Data System (ADS)

    Hoshi, Kazuki; Muramatsu, Kazuo; Sumi, Hisato; Nishioka, Yasushiro

    2016-04-01

    Ascorbic acid (AA) is a biologically friendly compound and exists in many products such as sports drinks, fruit, and even in human blood. Thus, a miniaturized and flexible ascorbic acid fuel cell (AAFC) is expected be a power source for portable or implantable electric devices. In this study, we fabricated an AAFC with anode and cathode dimensions of 3 × 10 mm2 made of a graphene-coated carbon fiber cloth (GCFC) and found that GCFC electrodes significantly improve the power generated by the AAFC. This is because the GCFC has more than two times the effective surface area of a conventional carbon fiber cloth and it can contain more enzymes. The power density of the AAFC in a phosphate buffer solution containing 100 mM AA at room temperature was 34.1 µW/cm2 at 0.46 V. Technical issues in applying the AAFC to portable devices are also discussed.

  8. Plastic fiber optics for micro-imaging of fluorescence signals in living cells

    NASA Astrophysics Data System (ADS)

    Sakurai, Takashi; Natsume, Mitsuo; Koida, Kowa

    2015-03-01

    The fiber-coupled microscope (FCM) enables in vivo imaging at deep sites in the tissues or organs that other optical techniques are unable to reach. To develop FCM-based intravital imaging, we employed a plastic optical fiber (POF) bundle that included more than 10,000-units of polystyrene core and polymethyl methacrylate cladding. Each POF had a diameter of less than 5 μm the tip of the bundle was less than 0.5 mm wide, and the flexible wire had a length of 1,000 mm. The optical performance of the plastic FCM was sufficient for detection of significant signal changes in an acinus of rat pancreas labeled with a calcium ion-sensitive fluorescent dye. In the future, the potential power of plastic FCM is expected to increase, enabling analysis of structure and organization of specific functions in live cells within vulnerable organs.

  9. Cut-off analysis of 19-cell Yb-doped double-cladding rod-type photonic crystal fibers.

    PubMed

    Poli, F; Coscelli, E; Alkeskjold, T T; Passaro, D; Cucinotta, A; Leick, L; Broeng, J; Selleri, S

    2011-05-09

    Yb-doped double-cladding large mode area rod-type photonic crystal fibers are a key component for power scaling in fiber laser systems. Recently, designs with 19-cell core defect, that is with 19 missing air-holes in the center of the photonic crystal cladding, have been proposed, with reported core diameter up to 100 μm. In this paper an analysis of the cut-off wavelength of the first high-order mode in such low-NA fibers is reported, accounting for different approaches for the definition of the cladding effective index. Results have shown that taking into account the finite fiber cross-section and considering the first cladding mode of the actual fiber is mandatory to obtain a correct estimate of the cut-off wavelength.

  10. In vitro cytotoxicity and transforming potential of industrial carbon dust (fibers and particles) in syrian hamster embryo (SHE) cells.

    PubMed

    Darne, C; Terzetti, F; Coulais, C; Fournier, J; Guichard, Y; Gaté, L; Binet, S

    2010-07-01

    Carbon fibers have many applications, mainly in high-tech industries such as the aviation industry. Eleven carbon samples (fibers and particles) coming from an aeronautic group were tested for their cytotoxicity and carcinogenic potential using in vitro short-term assays in Syrian hamster embryo cells. These samples were taken during each important step of the process, i.e. from the initial heating of polyacrylonitrile fibers to pure carbon fibers. They were compared to an asbestos fiber, an amorphous silica, and two commercial graphite powders. Their physical-chemical characteristics and their capacity to release reactive oxygen species (ROS) were determined. This study showed that none of the carbon samples was able to generate ROS as measured by Electron Paramagnetic Resonance analysis, and in our biological assays, they demonstrated no morphological transformation potential and low cytotoxicity compared to positive control (chrysotile asbestos).

  11. Influence of parallel fiber-Purkinje cell synapse formation on postnatal development of climbing fiber-Purkinje cell synapses in the cerebellum.

    PubMed

    Hashimoto, K; Yoshida, T; Sakimura, K; Mishina, M; Watanabe, M; Kano, M

    2009-09-01

    The climbing fiber (CF) to Purkinje cell (PC) synapse in the cerebellum provides an ideal model for the study of developmental rearrangements of neural circuits. At birth, each PC is innervated by multiple CFs. These surplus CFs are eliminated during postnatal development, and mono innervation is attained by postnatal day 20 (P20) in mice. Earlier studies on spontaneous mutant mice and animals with "hypogranular" cerebella indicate that regression of surplus CFs requires normal generation of granule cells and their axons, parallel fibers (PFs), and normal formation of PF-PC synapses. Our understanding of how PF-PC synapse formation affects development of CF-PC synapse has been greatly advanced by analyses of mutant mice deficient in glutamate receptor delta2 subunit (GluRdelta2), an orphan receptor expressed selectively in PCs. Deletion of GluRdelta2 results in impairment of PF-PC synapse formation, which leads to defects in development of CF-PC synapses. In this article, we review how impaired PF-PC synapse formation affects wiring of CFs to PCs based mostly on our data on GluRdelta2 knockout mice. We propose a new scheme that CF-PC synapses are shaped by the three consecutive events, namely functional differentiation of multiple CFs into one strong and a few weak inputs from P3 to P7, "early phase" of CF synapse elimination from P7 to around P11, and "late phase" of CF synapse elimination from around P12. Normal PF-PC synapse formation is required for the "late phase" of CF synapse elimination.

  12. GMP-Compliant Expansion of Clinical-Grade Human Mesenchymal Stromal/Stem Cells Using a Closed Hollow Fiber Bioreactor.

    PubMed

    Barckhausen, Christina; Rice, Brent; Baila, Stefano; Sensebé, Luc; Schrezenmeier, Hubert; Nold, Philipp; Hackstein, Holger; Rojewski, Markus Thomas

    2016-01-01

    This chapter describes a method for GMP-compliant expansion of human mesenchymal stromal/stem cells (hMSC) from bone marrow aspirates, using the Quantum(®) Cell Expansion System from Terumo BCT. The Quantum system is a functionally closed, automated hollow fiber bioreactor system designed to reproducibly grow cells in either GMP or research laboratory environments. The chapter includes protocols for preparation of media, setup of the Quantum system, coating of the hollow fiber bioreactor, as well as loading, feeding, and harvesting of cells. We suggest a panel of quality controls for the starting material, the interim product, as well as the final product.

  13. Cytotoxic and oxidative effects induced by man-made vitreous fibers (MMVFs) in a human mesothelial cell line.

    PubMed

    Cavallo, Delia; Campopiano, Antonella; Cardinali, Giorgia; Casciardi, Stefano; De Simone, Paolo; Kovacs, Daniela; Perniconi, Barbara; Spagnoli, Giuseppe; Ursini, Cinzia L; Fanizza, Carla

    2004-09-01

    The introduction of man-made vitreous fibers (MMVFs) as a substitute for asbestos in industrial and residential applications raises concerns about their potential health hazards. The aim of our study was to assess cytotoxic and oxidative effects induced on a human mesothelial cell line (MeT-5A) by exposure to glass wool (GW), rock wool (RW) and refractory ceramic fibers (RCF) in comparison with crocidolite asbestos (CR). MeT-5A cells were exposed for 24 h to 2, 5 and 10 microg/cm2 of MMVF and crocidolite fibers and analysed by scanning electron microscope (SEM) for cell surface alterations. Cells were exposed for 2 h to 1, 2, 5 and 10 microg/cm2 of the same fibers and analysed by enzyme Fpg-modified comet test for direct and oxidative DNA damage. SEM revealed loss of microvilli in cells exposed to RCF and numerous blebs in cells exposed to higher doses of RW. Comet test showed significant direct DNA damage in cells exposed to RCF even at the lowest dose. Comet test with Fpg, that permits the detection of oxided DNA bases, showed significant oxidative DNA damage in cells exposed to higher doses of RW. The presence of DNA damage and alterations of cell surface induced by low doses of RCF and the presence of oxidative DNA damage and blebs on cell surface in cells exposed to higher dose of RW suggest possible cytotoxic, oxidative and genotoxic effects for these MMVFs.

  14. Influence of exercise contraction mode and protein supplementation on human skeletal muscle satellite cell content and muscle fiber growth

    PubMed Central

    Farup, Jean; Rahbek, Stine Klejs; Riis, Simon; Vendelbo, Mikkel Holm; de Paoli, Frank

    2014-01-01

    Skeletal muscle satellite cells (SCs) are involved in remodeling and hypertrophy processes of skeletal muscle. However, little knowledge exists on extrinsic factors that influence the content of SCs in skeletal muscle. In a comparative human study, we investigated the muscle fiber type-specific association between emergence of satellite cells (SCs), muscle growth, and remodeling in response to 12 wk unilateral resistance training performed as eccentric (Ecc) or concentric (Conc) resistance training ± whey protein (Whey, 19.5 g protein + 19.5 g glucose) or placebo (Placebo, 39 g glucose) supplementation. Muscle biopsies (vastus lateralis) were analyzed for fiber type-specific SCs, myonuclei, and fiber cross-sectional area (CSA). Following training, SCs increased with Conc in both type I and type II fibers (P < 0.01) and exhibited a group difference from Ecc (P < 0.05), which did not increase. Myonuclei content in type I fibers increased in all groups (P < 0.01), while a specific accretion of myonuclei in type II fibers was observed in the Whey-Conc (P < 0.01) and Placebo-Ecc (P < 0.01) groups. Similarly, whereas type I fiber CSA increased independently of intervention (P < 0.001), type II fiber CSA increased exclusively with Whey-Conc (P < 0.01) and type II fiber hypertrophy correlated with whole muscle hypertrophy exclusively following Conc training (P < 0.01). In conclusion, isolated concentric knee extensor resistance training appears to constitute a stronger driver of SC content than eccentric resistance training while type II fiber hypertrophy was accentuated when combining concentric resistance training with whey protein supplementation. PMID:25103976

  15. Influence of exercise contraction mode and protein supplementation on human skeletal muscle satellite cell content and muscle fiber growth.

    PubMed

    Farup, Jean; Rahbek, Stine Klejs; Riis, Simon; Vendelbo, Mikkel Holm; Paoli, Frank de; Vissing, Kristian

    2014-10-15

    Skeletal muscle satellite cells (SCs) are involved in remodeling and hypertrophy processes of skeletal muscle. However, little knowledge exists on extrinsic factors that influence the content of SCs in skeletal muscle. In a comparative human study, we investigated the muscle fiber type-specific association between emergence of satellite cells (SCs), muscle growth, and remodeling in response to 12 wk unilateral resistance training performed as eccentric (Ecc) or concentric (Conc) resistance training ± whey protein (Whey, 19.5 g protein + 19.5 g glucose) or placebo (Placebo, 39 g glucose) supplementation. Muscle biopsies (vastus lateralis) were analyzed for fiber type-specific SCs, myonuclei, and fiber cross-sectional area (CSA). Following training, SCs increased with Conc in both type I and type II fibers (P < 0.01) and exhibited a group difference from Ecc (P < 0.05), which did not increase. Myonuclei content in type I fibers increased in all groups (P < 0.01), while a specific accretion of myonuclei in type II fibers was observed in the Whey-Conc (P < 0.01) and Placebo-Ecc (P < 0.01) groups. Similarly, whereas type I fiber CSA increased independently of intervention (P < 0.001), type II fiber CSA increased exclusively with Whey-Conc (P < 0.01) and type II fiber hypertrophy correlated with whole muscle hypertrophy exclusively following Conc training (P < 0.01). In conclusion, isolated concentric knee extensor resistance training appears to constitute a stronger driver of SC content than eccentric resistance training while type II fiber hypertrophy was accentuated when combining concentric resistance training with whey protein supplementation.

  16. The effect of nutritional status and muscle fiber type on myogenic satellite cell fate and apoptosis.

    PubMed

    Powell, D J; McFarland, D C; Cowieson, A J; Muir, W I; Velleman, S G

    2014-01-01

    Satellite cells (SC) are multipotential stem cells that can be induced by nutrition to alter their cellular developmental fate, which may vary depending on their fiber type origin. The objective of the current study was to determine the effect of restricting protein synthesis on inducing adipogenic transdifferentiation and apoptosis of SC originating from fibers of the fast glycolytic pectoralis major (p. major) and fast oxidative and glycolytic biceps femoris (b. femoris) muscles of the chicken. The availability of the essential sulfur amino acids Met and Cys was restricted to regulate protein synthesis during SC proliferation and differentiation. The SC were cultured and treated with 1 of 6 Met/Cys concentrations: 60/192, 30/96 (control), 7.5/24, 3/9.6, 1/3.2, or 0/0 mg/L. Reductions in Met/Cys concentrations from the control level resulted in increased lipid staining and expression of the adipogenic marker genes peroxisome proliferator-activated receptor gamma and stearoyl-CoA desaturase during differentiation in the p. major SC. Although b. femoris SC had increased lipid staining at lower Met/Cys concentrations, there was no increase in expression of either adipogenic gene. For both muscle types, SC Met/Cys, concentration above the control increased the expression of peroxisome proliferator-activated receptor gamma and stearoyl-CoA desaturase during differentiation. As Met/Cys concentration was decreased during proliferation, a dose-dependent decline in all apoptotic cells occurred except for early apoptotic cells in the p. major, which had no treatment effect (P < 0.05). During differentiation, decreasing Met/Cys concentration caused an increase in early apoptotic cells in both fiber types and no effect on late apoptotic cells except for an increase in the p. major 7.5/24 mg/L of Met/Cys treatment. In general, the viability of the SC was unaffected by the Met/Cys concentration except during proliferation in the p. major 0/0 mg/L of Met/Cys treatment, which

  17. Multifunctional integration of thin-film silicon solar cells on carbon-fiber-reinforced epoxy composites

    SciTech Connect

    Jason Maung, K.; Hahn, H. Thomas; Ju, Y.S.

    2010-03-15

    Multifunction integration of solar cells in load-bearing structures can enhance overall system performance by reducing parasitic components and material redundancy. The article describes a manufacturing strategy, named the co-curing scheme, to integrate thin-film silicon solar cells on carbon-fiber-reinforced epoxy composites and eliminate parasitic packaging layers. In this scheme, an assembly of a solar cell and a prepreg is cured to form a multifunctional composite in one processing step. The photovoltaic performance of the manufactured structures is then characterized under controlled cyclic mechanical loading. The study finds that the solar cell performance does not degrade under 0.3%-strain cyclic tension loading up to 100 cycles. Significant degradation, however, is observed when the magnitude of cyclic loading is increased to 1% strain. The present study provides an initial set of data to guide and motivate further studies of multifunctional energy harvesting structures. (author)

  18. Diffuse fluorescence fiber probe for in vivo detection of circulating cells

    NASA Astrophysics Data System (ADS)

    Pera, Vivian; Tan, Xuefei; Runnels, Judith; Sardesai, Neha; Lin, Charles P.; Niedre, Mark

    2017-03-01

    There has been significant recent interest in the development of technologies for enumeration of rare circulating cells directly in the bloodstream in many areas of research, for example, in small animal models of circulating tumor cell dissemination during cancer metastasis. We describe a fiber-based optical probe that allows fluorescence detection of labeled circulating cells in vivo in a diffuse reflectance configuration. We validated this probe in a tissue-mimicking flow phantom model in vitro and in nude mice injected with fluorescently labeled multiple myeloma cells in vivo. Compared to our previous work, this design yields an improvement in detection signal-to-noise ratio of 10 dB, virtually eliminates problematic motion artifacts due to mouse breathing, and potentially allows operation in larger animals and limbs.

  19. Computational Modeling of Single-Cell Migration: The Leading Role of Extracellular Matrix Fibers

    PubMed Central

    Schlüter, Daniela K.; Ramis-Conde, Ignacio; Chaplain, Mark A.J.

    2012-01-01

    Cell migration is vitally important in a wide variety of biological contexts ranging from embryonic development and wound healing to malignant diseases such as cancer. It is a very complex process that is controlled by intracellular signaling pathways as well as the cell’s microenvironment. Due to its importance and complexity, it has been studied for many years in the biomedical sciences, and in the last 30 years it also received an increasing amount of interest from theoretical scientists and mathematical modelers. Here we propose a force-based, individual-based modeling framework that links single-cell migration with matrix fibers and cell-matrix interactions through contact guidance and matrix remodelling. With this approach, we can highlight the effect of the cell’s environment on its migration. We investigate the influence of matrix stiffness, matrix architecture, and cell speed on migration using quantitative measures that allow us to compare the results to experiments. PMID:22995486

  20. Fiber-Optic Array Scanning Technology (FAST) for Detection and Molecular Characterization of Circulating Tumor Cells.

    PubMed

    Ao, Zheng; Liu, Xiaohe

    2017-01-01

    Circulating tumor cell (CTC) as an important component in "liquid biopsy" holds crucial clinical relevance in cancer prognosis, treatment efficiency evaluation, prediction and potentially early detection. Here, we present a Fiber-optic Array Scanning Technology (FAST) that enables antigen-agnostic, size-agnostic detection of CTC. By immunofluorescence staining detection of a combination of a panel of markers, FAST technology can be applied to detect rare CTC in non-small cell lung cancer (NSCLC) setting with high sensitivity and specificity. In combination with Automated Digital Microscopy (ADM) platform, companion markers on CTC such as Vimentin and Programmed death-ligand 1 (PD-L1) can also be analyzed to further characterize these CTCs. FAST data output is also compatible with downstream single cell picking platforms. Single cell can be isolated post ADM confirmation and used for "actionable" genetic mutations analysis.

  1. Detection of synchrony in the activity of auditory nerve fibers by octopus cells of the mammalian cochlear nucleus.

    PubMed

    Oertel, D; Bal, R; Gardner, S M; Smith, P H; Joris, P X

    2000-10-24

    The anatomical and biophysical specializations of octopus cells allow them to detect the coincident firing of groups of auditory nerve fibers and to convey the precise timing of that coincidence to their targets. Octopus cells occupy a sharply defined region of the most caudal and dorsal part of the mammalian ventral cochlear nucleus. The dendrites of octopus cells cross the bundle of auditory nerve fibers just proximal to where the fibers leave the ventral and enter the dorsal cochlear nucleus, each octopus cell spanning about one-third of the tonotopic array. Octopus cells are excited by auditory nerve fibers through the activation of rapid, calcium-permeable, alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate receptors. Synaptic responses are shaped by the unusual biophysical characteristics of octopus cells. Octopus cells have very low input resistances (about 7 M Omega), and short time constants (about 200 microsec) as a consequence of the activation at rest of a hyperpolarization-activated mixed-cation conductance and a low-threshold, depolarization-activated potassium conductance. The low input resistance causes rapid synaptic currents to generate rapid and small synaptic potentials. Summation of small synaptic potentials from many fibers is required to bring an octopus cell to threshold. Not only does the low input resistance make individual excitatory postsynaptic potentials brief so that they must be generated within 1 msec to sum but also the voltage-sensitive conductances of octopus cells prevent firing if the activation of auditory nerve inputs is not sufficiently synchronous and depolarization is not sufficiently rapid. In vivo in cats, octopus cells can fire rapidly and respond with exceptionally well-timed action potentials to periodic, broadband sounds such as clicks. Thus both the anatomical specializations and the biophysical specializations make octopus cells detectors of the coincident firing of their auditory nerve fiber inputs.

  2. Detection of synchrony in the activity of auditory nerve fibers by octopus cells of the mammalian cochlear nucleus

    PubMed Central

    Oertel, Donata; Bal, Ramazan; Gardner, Stephanie M.; Smith, Philip H.; Joris, Philip X.

    2000-01-01

    The anatomical and biophysical specializations of octopus cells allow them to detect the coincident firing of groups of auditory nerve fibers and to convey the precise timing of that coincidence to their targets. Octopus cells occupy a sharply defined region of the most caudal and dorsal part of the mammalian ventral cochlear nucleus. The dendrites of octopus cells cross the bundle of auditory nerve fibers just proximal to where the fibers leave the ventral and enter the dorsal cochlear nucleus, each octopus cell spanning about one-third of the tonotopic array. Octopus cells are excited by auditory nerve fibers through the activation of rapid, calcium-permeable, α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate receptors. Synaptic responses are shaped by the unusual biophysical characteristics of octopus cells. Octopus cells have very low input resistances (about 7 MΩ), and short time constants (about 200 μsec) as a consequence of the activation at rest of a hyperpolarization-activated mixed-cation conductance and a low-threshold, depolarization-activated potassium conductance. The low input resistance causes rapid synaptic currents to generate rapid and small synaptic potentials. Summation of small synaptic potentials from many fibers is required to bring an octopus cell to threshold. Not only does the low input resistance make individual excitatory postsynaptic potentials brief so that they must be generated within 1 msec to sum but also the voltage-sensitive conductances of octopus cells prevent firing if the activation of auditory nerve inputs is not sufficiently synchronous and depolarization is not sufficiently rapid. In vivo in cats, octopus cells can fire rapidly and respond with exceptionally well-timed action potentials to periodic, broadband sounds such as clicks. Thus both the anatomical specializations and the biophysical specializations make octopus cells detectors of the coincident firing of their auditory nerve fiber inputs. PMID:11050208

  3. Neutrophil and asbestos fiber-induced cytotoxicity in cultured human mesothelial and bronchial epithelial cells.

    PubMed

    Kinnula, V L; Raivio, K O; Linnainmaa, K; Ekman, A; Klockars, M

    1995-03-01

    This study investigates reactive oxygen species generation and oxidant-related cytotoxicity induced by amosite asbestos fibers and polymorphonuclear leucocytes (PMNs) in human mesothelial cells and human bronchial epithelial cells in vitro. Transformed human pleural mesothelial cells (MET 5A) and bronchial epithelial cells (BEAS 2B) were treated with amosite (2 micrograms/cm2) for 48 h. After 24 h of incubation, the cells were exposed for 1 h to nonactivated or amosite (50 micrograms) activated PMNs, washed, and incubated for another 23 h. Reactive oxygen species generation by the PMNs and the target cells was measured by chemiluminescence. Cell injury was assessed by cellular adenine nucleotide depletion, extracellular release of nucleotides, and lactate dehydrogenase (LDH). Amosite-activated (but also to a lesser degree nonactivated) PMNs released substantial amounts of reactive oxygen metabolites, whereas the chemiluminescence of amosite-exposed mesothelial cells and epithelial cells did not differ from the background. Amosite treatment (48 h) of the target cells did not change intracellular adenine nucleotides (ATP, ADP, AMP) or nucleotide catabolite products (xanthine, hypoxanthine, and uric acid). When the target cells were exposed to nonactivated PMNs, significant adenine nucleotide depletion and nucleotide catabolite accumulation was observed in mesothelial cells only. In separate experiments, when the target cells were exposed to amosite-activated PMNs, the target cell injury was further potentiated compared with the amosite treatment alone or exposure to nonactivated PMNs. In conclusion, this study suggests the importance of inflammatory cell-derived free radicals in the development of amosite-induced mesothelial cell injury.

  4. Intraluminal acid activates esophageal nodose C fibers after mast cell activation

    PubMed Central

    Zhang, Shizhong; Liu, Zhenyu; Heldsinger, Andrea; Owyang, Chung

    2013-01-01

    Acid reflux in the esophagus can induce esophageal painful sensations such as heartburn and noncardiac chest pain. The mechanisms underlying acid-induced esophageal nociception are not clearly understood. In our previous studies, we characterized esophageal vagal nociceptive afferents and defined their responses to noxious mechanical and chemical stimulation. In the present study, we aim to determine their responses to intraluminal acid infusion. Extracellular single-unit recordings were performed in nodose ganglion neurons with intact nerve endings in the esophagus using ex vivo esophageal-vagal preparations. Action potentials evoked by esophageal intraluminal acid perfusion were compared in naive and ovalbumin (OVA)-challenged animals, followed by measurements of transepithelial electrical resistance (TEER) and the expression of tight junction proteins (zona occludens-1 and occludin). In naive guinea pigs, intraluminal infusion with either acid (pH = 2–3) or capsaicin did not evoke an action potential discharge in esophageal nodose C fibers. In OVA-sensitized animals, following esophageal mast cell activation by in vivo OVA inhalation, intraluminal acid infusion for about 20 min started to evoke action potential discharges. This effect is further confirmed by selective mast cell activation using in vitro tissue OVA challenge in esophageal-vagal preparations. OVA inhalation leads to decreased TEER and zona occludens-1 expression, suggesting an impaired esophageal epithelial barrier function after mast cell activation. These data for the first time provide direct evidence of intraluminal acid-induced activation of esophageal nociceptive C fibers and suggest that mast cell activation may make esophageal epithelium more permeable to acid, which subsequently may increase esophageal vagal nociceptive C fiber activation. PMID:24264049

  5. Removal of digoxin and doxorubicin by multidrug resistance protein-overexpressed cell culture in hollow fiber.

    PubMed

    Tsuruoka, S; Sugimoto, K I; Ueda, K; Suzuki, M; Imai, M; Fujimura, A

    1999-07-01

    Drug removal by hemoperfusion is not effective because of its lower capacity and nonspecificity. We invented a new hybrid type of hemodialysis system. An immortalized proximal tubular cell line (PCTL) overexpressing human multidrug resistance protein-1 (MDR-1) was cultured either on polus filter membranes or on hollow fiber modules. The modules were incubated in an incubator conditioned with 95% O2/5% CO2 that was kept at 37 degrees C. At 10 days on culture, the drug-transporting capacity of these systems was examined. MDR was successfully expressed in the PCTL as evaluated by Western blot. Basolateral to apical transport of 3H-digoxin, a substrate of MDR, was examined by using the cells cultured on a microporous membrane. PCTL-MDR showed a 10-fold increase in MDR protein and a 12-fold increase of 3H-digoxin transport through a cell layer on a microporous membrane. The increase of the transport was abolished by the addition of 5 microM verapamil, an inhibitor of MDR, to the apical side. When digoxin or doxorubicin was infused in the capillary side of the hollow fiber modules after 10 days on culture, the largest portion of the drugs was transported to the pericapillary side (P < 0.001). This transport was also abolished by an addition of verapamil to the pericapillary side. Transport of para-aminohippurate was not different between two cells, and inulin was not transported in this system. The hybrid hollow fiber system can selectively remove a significant amount of drugs that have an affinity to MDR from the medium, and perfuse them to the capillary side in vitro.

  6. Fibrous hydrogel scaffolds with cells embedded in the fibers as a potential tissue scaffold for skin repair.

    PubMed

    Lin, Hsin-Yi; Peng, Chih-Wei; Wu, Wei-Wen

    2014-01-01

    A novel approach was undertaken to create a potential skin wound dressing. L929 fibroblast cells and alginate solution were simultaneously dispensed into a calcium chloride solution using a three-dimensional plotting system to manufacture a fibrous alginate scaffold with interconnected pores. These cells were then embedded in the alginate hydrogel fibers of the scaffold. A conventional scaffold with cells directly seeded on the fiber surface was used as a control. The encapsulated fibroblasts made using the co-dispensing method distributed homogeneously within the scaffold and showed the delayed formation of large cell aggregates compared to the control. The cells embedded in the hydrogel fibers also deposited more type I collagen in the extracellular matrix and expressed higher levels of fgf11 and fn1 than the control, indicating increased cellular proliferation and attachment. The results indicate that the novel co-dispensing alginate scaffold may promote skin regeneration better than the conventional directly-seeded scaffold.

  7. Miniature fiber optic spectrometer-based quantitative fluorescence resonance energy transfer measurement in single living cells

    NASA Astrophysics Data System (ADS)

    Chai, Liuying; Zhang, Jianwei; Zhang, Lili; Chen, Tongsheng

    2015-03-01

    Spectral measurement of fluorescence resonance energy transfer (FRET), spFRET, is a widely used FRET quantification method in living cells today. We set up a spectrometer-microscope platform that consists of a miniature fiber optic spectrometer and a widefield fluorescence microscope for the spectral measurement of absolute FRET efficiency (E) and acceptor-to-donor concentration ratio (RC) in single living cells. The microscope was used for guiding cells and the spectra were simultaneously detected by the miniature fiber optic spectrometer. Moreover, our platform has independent excitation and emission controllers, so different excitations can share the same emission channel. In addition, we developed a modified spectral FRET quantification method (mlux-FRET) for the multiple donors and multiple acceptors FRET construct (mD˜nA) sample, and we also developed a spectra-based 2-channel acceptor-sensitized FRET quantification method (spE-FRET). We implemented these modified FRET quantification methods on our platform to measure the absolute E and RC values of tandem constructs with different acceptor/donor stoichiometries in single living Huh-7 cells.

  8. Enhanced adhesion and proliferation of human umbilical vein endothelial cells on conductive PANI-PCL fiber scaffold by electrical stimulation.

    PubMed

    Li, Yumei; Li, Xiang; Zhao, Rui; Wang, Chuying; Qiu, Fangping; Sun, Bolun; Ji, He; Qiu, Ju; Wang, Ce

    2017-03-01

    Recently, electrically conductive biomaterial scaffolds have shown great potential in tissue regeneration. Herein, we reported an electrically conductive polyaniline (PANI) coated poly(ε-caprolactone) (PCL) electrospun micron-fiber scaffold for the enhanced attachment and proliferation of human umbilical vein endothelial cells (HUVECs) under electrical stimulation conditions. After the O2 plasma treatment toward PCL electrospun fiber, PANI could be polymerized onto their surfaces successfully. The obtained PANI-PCL fibers were characterized by SEM observations, FT-IR spectra, XPS analysis, and water contact angle measurement. The mechanical tests indicated that the fibers could satisfy the practical vascular scaffold requirements. The conductivity of the PANI-PCL fibers was 6.71×10(-3)S/cm which could provide a conductive in-vitro platform to study the effect of electrical stimulation on HUVECs proliferation. When PANI-coated PCL fibers were compared with PCL fibers, HUVECs exhibited highly enhanced adhesion and viability, especially under electrical stimulation (ES) of 200, 300, and 400mV/cm. Proliferation of HUVECs on PANI-PCL fibers was strongly dependent on electrical stimulation intensity. The results showed new insights into conductive scaffolds for vascular tissue engineering. Copyright © 2016. Published by Elsevier B.V.

  9. The effect of various denier capillary channel polymer fibers on the alignment of NHDF cells and type I collagen.

    PubMed

    Sinclair, Kristofer D; Webb, Ken; Brown, Philip J

    2010-12-15

    If tissue engineers are to successfully repair and regenerate native tendons and ligaments, it will be essential to implement contact guidance to induce cellular and type I collagen alignment to replicate the native structure. Capillary channel polymer (CC-P) fibers fabricated by melt-extrusion have aligned micrometer scale surface channels that may serve the goal of achieving biomimetic, physical templates for ligament growth and regeneration. Previous work characterizing the behavior of normal human dermal fibroblasts (NHDF), on the 19 denier per filament (dpf) CC-P fibers, demonstrated a need for improved cellular and type I collagen alignment. Therefore, 5 and 9 dpf CC-P fibers were manufactured to determine whether their channel dimensions would achieve greater alignment. A 29 dpf CC-P fiber was also examined to determine whether cellular guidance could still be achieved within the larger dimensions of the fiber's channels. The 9 dpf CC-P fiber appeared to approach the topographical constraints necessary to induce the cellular and type I collagen architecture that most closely mirrored that of native ACL tissue. This work demonstrated that the novel cross-section of the CC-P fiber geometry could approach the necessary surface topography to align NHDF cells along the longitudinal axis of each fiber.

  10. Intake of fiber and fiber-rich plant foods is associated with a lower risk of renal cell carcinoma in a large US cohort1234

    PubMed Central

    Park, Yikyung; Chow, Wong-Ho; Graubard, Barry I; Hollenbeck, Albert R; Sinha, Rashmi

    2013-01-01

    Background: Plant-based and fiber-rich diets high in vegetables, fruit, and whole grains are recommended to prevent cancer and chronic conditions associated with renal cell carcinoma (RCC), such as obesity, hypertension, and diabetes. Diet may play a role in the etiology of RCC directly and/or indirectly. Objective: In a large prospective cohort of US men and women, we comprehensively investigated dietary intake and food sources of fiber in relation to RCC risk. Design: Participants of the NIH-AARP Diet and Health Study (n = 491,841) completed a self-administered questionnaire of demographics, diet, lifestyle, and medical history. Over 9 (mean) years of follow-up we identified 1816 incident cases of RCC. HRs and 95% CIs were estimated within quintiles by using multivariable Cox proportional hazards regression. Results: Total dietary fiber intake was associated with a significant 15–20% lower risk of RCC in the 2 highest quintiles compared with the lowest (P-trend = 0.005). Intakes of legumes, whole grains, and cruciferous vegetables were also associated with a 16–18% reduced risk of RCC. Conversely, refined grain intake was positively associated with RCC risk in a comparison of quintile 5 with quintile 1 (HR: 1.19; 95% CI: 1.02, 1.39; P-trend = 0.04). The inverse association between fiber intake and RCC was consistent among participants who never smoked, had a body mass index [BMI (in kg/m2)] <30, and did not report a history of diabetes or hypertension. Conclusions: Intake of fiber and fiber-rich plant foods was associated with a significantly lower risk of RCC in this large US cohort. This trial was registered at clinicaltrials.gov as NCT00340015. PMID:23515007

  11. Three-dimensional multilayers of smooth muscle cells as a new experimental model for vascular elastic fiber formation studies.

    PubMed

    Ishiwata, Ryo; Yokoyama, Utako; Matsusaki, Michiya; Asano, Yoshiya; Kadowaki, Koji; Ichikawa, Yasuhiro; Umemura, Masanari; Fujita, Takayuki; Minamisawa, Susumu; Shimoda, Hiroshi; Akashi, Mitsuru; Ishikawa, Yoshihiro

    2014-04-01

    Elastic fiber formation is disrupted with age and by health conditions including aneurysms and atherosclerosis. Despite considerable progress in the understanding of elastogenesis using the planar culture system and genetically modified animals, it remains difficult to restore elastic fibers in diseased vessels. To further study the molecular mechanisms, in vitro three-dimensional vascular constructs need to be established. We previously fabricated vascular smooth muscle cells (SMCs) into three-dimensional cellular multilayers (3DCMs) using a hierarchical cell manipulation technique, in which cells were coated with fibronectin-gelatin nanofilms to provide adhesive nano-scaffolds. Since fibronectin is known to assemble and activate elastic fiber-related molecules, we further optimized culture conditions. Elastica stain, immunofluorescence, and electron microscopic analysis demonstrated that 3DCMs, which consisted of seven layers of neonatal rat aortic SMCs cultured in 1% fetal bovine serum (FBS) in Dulbecco's modified Eagle's medium, exhibited layered elastic fibers within seven days of being in a static culture condition. In contrast, the application of adult SMCs, 10% FBS, ε-poly(lysine) as an alternative adhesive for fibronectin, or four-layered SMCs, failed to generate layered elastic fiber formation. Radioimmunoassay using [(3)H]valine further confirmed the greater amount of cross-linked elastic fibers in 3DCMs than in monolayered SMCs. Layered elastic fiber formation in 3DCMs was inhibited by the lysyl oxidase inhibitor β-aminopropionitrile, or prostaglandin E2. Furthermore, infiltration of THP-1-derived macrophages decreased the surrounding elastic fiber formation in 3DCMs. 3DCMs may offer a new experimental vascular model to explore pharmacological therapeutic strategies for disordered elastic fiber homeostasis. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  12. Carbon-fiber microelectrode amperometry reveals sickle-cell-induced inflammation and chronic morphine effects on single mast cells.

    PubMed

    Manning, Benjamin M; Hebbel, Robert P; Gupta, Kalpna; Haynes, Christy L

    2012-03-16

    Sickle cell disease, caused by a mutation of hemoglobin, is characterized by a complex pathophysiology including an important inflammatory component. Mast cells are tissue-resident leukocytes known to influence a range of immune functions in a variety of different ways, largely through the secretion of biologically active mediators from preformed granules. However, it is not understood how mast cells influence the inflammatory environment in sickle cell disease. A notable consequence of sickle cell disease is severe pain. Therefore, morphine is often used to treat this disease. Because mast cells express opioid receptors, it is pertinent to understand how chronic morphine exposure influences mast cell function and inflammation in sickle cell disease. Herein, carbon-fiber microelectrode amperometry (CFMA) was used to monitor the secretion of immunoactive mediators from single mast cells. CFMA enabled the detection and quantification of discrete exocytotic events from single mast cells. Mast cells from two transgenic mouse models expressing human sickle hemoglobin (hBERK1 and BERK) and a control mouse expressing normal human hemoglobin (HbA-BERK) were monitored using CFMA to explore the impact of sickle-cell-induced inflammation and chronic morphine exposure on mast cell function. This work, utilizing the unique mechanistic perspective provided by CFMA, describes how mast cell function is significantly altered in hBERK1 and BERK mice, including decreased serotonin released compared to HbA-BERK controls. Furthermore, morphine was shown to significantly increase the serotonin released from HbA-BERK mast cells and demonstrated the capacity to reverse the observed sickle-cell-induced changes in mast cell function.

  13. Long and short fiber amosite asbestos alters at a different extent the redox metabolism in human lung epithelial cells.

    PubMed

    Riganti, Chiara; Aldieri, Elisabetta; Bergandi, Loredana; Tomatis, Maura; Fenoglio, Ivana; Costamagna, Costanzo; Fubini, Bice; Bosia, Amalia; Ghigo, Dario

    2003-11-15

    The mechanism by which asbestos fibers are fibrogenic and tumorigenic is still matter of debate. The higher pathogenicity of longer fibers has been traditionally associated with their slower clearance in respiratory airways. However, short amosite fibers, obtained by grinding longer ones, exhibited a lower potential to damage nude DNA and a lower in vitro cytotoxicity. We have thus revisited the two sets of long and short fibers in order to compare their surface properties to their activity in cell systems. In this study we report that, in human lung epithelial cells A549, long amosite fibers, more effectively than the short ones, initiate free radical reactions, inhibit the glucose 6-phosphate dehydrogenase activity and the pentose phosphate pathway, decrease the intracellular level of reduced glutathione, and increase the generation of thiobarbituric acid reactive substances and the leakage of lactate dehydrogenase in the extracellular medium. These results suggest that the shortening of fibers by prolonged milling affects not only their biopersistence, but also their surface properties, hence their interaction with cellular metabolism. Our data provide also a mechanism by which asbestos fibers inhibit the pentose phosphate pathway, i.e., via the oxidative inhibition of glucose 6-phosphate dehydrogenase, which is prevented by reduced glutathione.

  14. Influence of the structure of poly (L-lactic acid) electrospun fibers on the bioactivity of endothelial cells: proliferation and inflammatory cytokines expression.

    PubMed

    Liu, Xiaoyan; Zhang, Xiazhi; Wu, Keke; Yang, Wufeng; Jiao, Yanpeng; Zhou, Changren

    2017-02-01

    Electrospinning has been used to fabricate random and aligned poly (L-lactic acid) (PLLA) fibers with three kinds of diameter under optimal conditions. The main purpose of this paper was to investigate the influence of the diameter and orientation of fibers on the bioactivity of endothelial cells, especially on the inflammatory cytokines expression. The morphology of electrospun fibers and the cells on the fibers after 3 and 6 days culture were observed by scanning electron microscopy. Also the cell proliferation activity and cell cycle were tested and the results showed that the random fibers were more favorable for endothelial cells growth. The effect of PLLA film (served as a control) and six kinds of PLLA fibers mats on the inflammatory cytokines expression after cells incubated for 2 and 4 days were investigated. It was concluded that there was more intense inflammatory cytokines expression by cells on flat PLLA film than that on electrospun fiber mats. Also the fiber diameter has greater effect on the activity and inflammatory cytokines expression of endothelial cells than the fiber orientation, in which fibers with smaller size has weaker inflammatory reaction.

  15. Identification and Ultrastructural Characterization of a Novel Nuclear Degradation Complex in Differentiating Lens Fiber Cells

    PubMed Central

    Costello, M. Joseph; Brennan, Lisa A.; Gilliland, Kurt O.; Johnsen, Sönke; Kantorow, Marc

    2016-01-01

    An unresolved issue in structural biology is how the encapsulated lens removes membranous organelles to carry out its role as a transparent optical element. In this ultrastructural study, we establish a mechanism for nuclear elimination in the developing chick lens during the formation of the organelle-free zone. Day 12–15 chick embryo lenses were examined by high-resolution confocal light microscopy and thin section transmission electron microscopy (TEM) following fixation in 10% formalin and 4% paraformaldehyde, and then processing for confocal or TEM as described previously. Examination of developing fiber cells revealed normal nuclei with dispersed chromatin and clear nucleoli typical of cells in active ribosome production to support protein synthesis. Early signs of nuclear degradation were observed about 300 μm from the lens capsule in Day 15 lenses where the nuclei display irregular nuclear stain and prominent indentations that sometimes contained a previously undescribed macromolecular aggregate attached to the nuclear envelope. We have termed this novel structure the nuclear excisosome. This complex by confocal is closely adherent to the nuclear envelope and by TEM appears to degrade the outer leaflet of the nuclear envelope, then the inner leaflet up to 500 μm depth. The images suggest that the nuclear excisosome separates nuclear membrane proteins from lipids, which then form multilamellar assemblies that stain intensely in confocal and in TEM have 5 nm spacing consistent with pure lipid bilayers. The denuded nucleoplasm then degrades by condensation and loss of structure in the range 600 to 700 μm depth producing pyknotic nuclear remnants. None of these stages display any classic autophagic vesicles or lysosomes associated with nuclei. Uniquely, the origin of the nuclear excisosome is from filopodial-like projections of adjacent lens fiber cells that initially contact, and then appear to fuse with the outer nuclear membrane. These filopodial

  16. Muscle cell membranes from early degeneration muscle cell fibers in Solenopsis are leaky to lanthanum: electron microscopy and X-ray analysis

    SciTech Connect

    Jones, R.G.; Davis, W.L.

    1985-06-01

    Lanthanum infusion techniques, transmission electron microscopy, and X-ray microanalysis were utilized to compare the permeability of muscle cell membranes from normal and degenerating muscle fibers of Solenopsis spp. In normal fibers, the electron-dense tracer was limited to components of the sarcotubular system. However, the insemination-induced degeneration of muscle fibers was characterized by the presence of an electron-dense precipitate within the myofibrils and mitochondria as well as in the extramyofibrillar spaces. The electron-dense material was subsequently identified by elemental analysis to be lanthanum. Such data indicate that one of the earliest stages of muscle degeneration involves an alteration in cell membrane permeability.

  17. A comparative evaluation of the effect of polymer chemistry and fiber orientation on mesenchymal stem cell differentiation

    PubMed Central

    Rowland, David C.L.; Aquilina, Thomas; Klein, Andrei; Hakimi, Osnat; Alexis‐Mouthuy, Pierre; Carr, Andrew J

    2016-01-01

    Abstract Bioengineered tissue scaffolds in combination with cells hold great promise for tissue regeneration. The aim of this study was to determine how the chemistry and fiber orientation of engineered scaffolds affect the differentiation of mesenchymal stem cells (MSCs). Adipogenic, chondrogenic, and osteogenic differentiation on aligned and randomly orientated electrospun scaffolds of Poly (lactic‐co‐glycolic) acid (PLGA) and Polydioxanone (PDO) were compared. MSCs were seeded onto scaffolds and cultured for 14 days under adipogenic‐, chondrogenic‐, or osteogenic‐inducing conditions. Cell viability was assessed by alamarBlue metabolic activity assays and gene expression was determined by qRT‐PCR. Cell‐scaffold interactions were visualized using fluorescence and scanning electron microscopy. Cells grew in response to scaffold fiber orientation and cell viability, cell coverage, and gene expression analysis showed that PDO supports greater multilineage differentiation of MSCs. An aligned PDO scaffold supports highest adipogenic and osteogenic differentiation whereas fiber orientation did not have a consistent effect on chondrogenesis. Electrospun scaffolds, selected on the basis of fiber chemistry and alignment parameters could provide great therapeutic potential for restoration of fat, cartilage, and bone tissue. This study supports the continued investigation of an electrospun PDO scaffold for tissue repair and regeneration and highlights the potential of optimizing fiber orientation for improved utility. © 2016 The Authors Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2843–2853, 2016. PMID:27399850

  18. Smooth Muscle Cell Alignment and Phenotype Control by Melt Spun Polycaprolactone Fibers for Seeding of Tissue Engineered Blood Vessels

    PubMed Central

    Agrawal, Animesh; Lee, Bae Hoon; Irvine, Scott A.; An, Jia; Bhuthalingam, Ramya; Singh, Vaishali; Low, Kok Yao; Chua, Chee Kai; Venkatraman, Subbu S.

    2015-01-01

    A method has been developed to induce and retain a contractile phenotype for vascular smooth muscle cells, as the first step towards the development of a biomimetic blood vessel construct with minimal compliance mismatch. Melt spun PCL fibers were deposited on a mandrel to form aligned fibers of 10 μm in diameter. The fibers were bonded into aligned arrangement through dip coating in chitosan solution. This formed a surface of parallel grooves, 10 μm deep by 10 μm across, presenting a surface layer of chitosan to promote cell surface interactions. The aligned fiber surface was used to culture cells present in the vascular wall, in particular fibroblasts and smooth muscle cells. This topography induced “surface guidance” over the orientation of the cells, which adopted an elongated spindle-like morphology, whereas cells on the unpatterned control surface did not show such orientation, assuming more rhomboid shapes. The preservation of VSMC contractile phenotype on the aligned scaffold was demonstrated by the retention of α-SMA expression after several days of culture. The effect was assessed on a prototype vascular graft prosthesis fabricated from polylactide caprolactone; VSMCs aligned longitudinally along a fiberless tube, whereas, for the aligned fiber coated tubes, the VSMCs aligned in the required circumferential orientation. PMID:26413093

  19. Light coupling into the Whispering Gallery Modes of a fiber array thin film solar cell for fixed partial Sun tracking

    PubMed Central

    Mariano, Marina; Rodríguez, Francisco J.; Romero-Gomez, Pablo; Kozyreff, Gregory; Martorell, Jordi

    2014-01-01

    We propose the use of whispering gallery mode coupling in a novel configuration based on implementing a thin film cell on the backside of an array of parallel fibers. We performed numerical calculations using the parameters of a thin film organic cell which demonstrate that light coupling becomes more effective as the angle for the incident light relative to the fiber array normal increases up to an optimal angle close to 55 deg. At this angle the power conversion efficiency of the fiber array solar cell we propose becomes 30% times larger than the one from an equivalent planar cell configuration. We demonstrate that the micro fiber array solar cell we propose may perform an effective partial tracking of the sun movement for over 100 degrees without any mechanical help. In addition, in the event that such fiber array cell would be installed with the adequate orientation on a vertical façade, an optimal photon-to-charge conversion would be reached for sunlight incident at 55 deg with respect to the horizon line, very close to the yearly average position for the sun at Latitude of 40 deg.

  20. Enhanced performance of electrospun carbon fibers modified with carbon nanotubes: promising electrodes for enzymatic biofuel cells

    NASA Astrophysics Data System (ADS)

    Both Engel, A.; Cherifi, A.; Tingry, S.; Cornu, D.; Peigney, A.; Laurent, Ch

    2013-06-01

    New nanostructured electrodes, promising for the production of clean and renewable energy in biofuel cells, were developed with success. For this purpose, carbon nanofibers were produced by the electrospinning of polyacrylonitrile solution followed by convenient thermal treatments (stabilization followed by carbonization at 1000, 1200 and 1400° C), and carbon nanotubes were adsorbed on the surfaces of the fibers by a dipping method. The morphology of the developed electrodes was characterized by several techniques (SEM, Raman spectroscopy, electrical conductivity measurement). The electrochemical properties were evaluated through cyclic voltammetry, where the influence of the carbonization temperature of the fibers and the beneficial contribution of the carbon nanotubes were observed through the reversibility and size of the redox peaks of K3Fe(CN)6 versus Ag/AgCl. Subsequently, redox enzymes were immobilized on the electrodes and the electroreduction of oxygen to water was realized as a test of their efficiency as biocathodes. Due to the fibrous and porous structure of these new electrodes, and to the fact that carbon nanotubes may have the ability to promote electron transfer reactions of redox biomolecules, the new electrodes developed were capable of producing higher current densities than an electrode composed only of electrospun carbon fibers.

  1. Enhanced performance of electrospun carbon fibers modified with carbon nanotubes: promising electrodes for enzymatic biofuel cells.

    PubMed

    Engel, A Both; Cherifi, A; Tingry, S; Cornu, D; Peigney, A; Laurent, Ch

    2013-06-21

    New nanostructured electrodes, promising for the production of clean and renewable energy in biofuel cells, were developed with success. For this purpose, carbon nanofibers were produced by the electrospinning of polyacrylonitrile solution followed by convenient thermal treatments (stabilization followed by carbonization at 1000, 1200 and 1400° C), and carbon nanotubes were adsorbed on the surfaces of the fibers by a dipping method. The morphology of the developed electrodes was characterized by several techniques (SEM, Raman spectroscopy, electrical conductivity measurement). The electrochemical properties were evaluated through cyclic voltammetry, where the influence of the carbonization temperature of the fibers and the beneficial contribution of the carbon nanotubes were observed through the reversibility and size of the redox peaks of K3Fe(CN)6 versus Ag/AgCl. Subsequently, redox enzymes were immobilized on the electrodes and the electroreduction of oxygen to water was realized as a test of their efficiency as biocathodes. Due to the fibrous and porous structure of these new electrodes, and to the fact that carbon nanotubes may have the ability to promote electron transfer reactions of redox biomolecules, the new electrodes developed were capable of producing higher current densities than an electrode composed only of electrospun carbon fibers.

  2. Chromatin remodeling enzyme Brg1 is required for mouse lens fiber cell terminal differentiation and its denucleation

    PubMed Central

    2010-01-01

    Background Brahma-related gene 1 (Brg1, also known as Smarca4 and Snf2β) encodes an adenosine-5'-triphosphate (ATP)-dependent catalytical subunit of the (switch/sucrose nonfermentable) (SWI/SNF) chromatin remodeling complexes. SWI/SNF complexes are recruited to chromatin through multiple mechanisms, including specific DNA-binding factors (for example, heat shock transcription factor 4 (Hsf4) and paired box gene 6 (Pax6)), chromatin structural proteins (for example, high-mobility group A1 (HMGA1)) and/or acetylated core histones. Previous studies have shown that a single amino acid substitution (K798R) in the Brg1 ATPase domain acts via a dominant-negative (dn) mechanism. Genetic studies have demonstrated that Brg1 is an essential gene for early (that is, prior implantation) mouse embryonic development. Brg1 also controls neural stem cell maintenance, terminal differentiation of multiple cell lineages and organs including the T-cells, glial cells and limbs. Results To examine the roles of Brg1 in mouse lens development, a dnBrg1 transgenic construct was expressed using the lens-specific αA-crystallin promoter in postmitotic lens fiber cells. Morphological studies revealed abnormal lens fiber cell differentiation in transgenic lenses resulting in cataract. Electron microscopic studies showed abnormal lens suture formation and incomplete karyolysis (that is, denucleation) of lens fiber cells. To identify genes regulated by Brg1, RNA expression profiling was performed in embryonic day 15.5 (E15.5) wild-type and dnBrg1 transgenic lenses. In addition, comparisons between differentially expressed genes in dnBrg1 transgenic, Pax6 heterozygous and Hsf4 homozygous lenses identified multiple genes coregulated by Brg1, Hsf4 and Pax6. DNase IIβ, a key enzyme required for lens fiber cell denucleation, was found to be downregulated in each of the Pax6, Brg1 and Hsf4 model systems. Lens-specific deletion of Brg1 using conditional gene targeting demonstrated that Brg1 was

  3. Guidance of in vitro migration of human mesenchymal stem cells and in vivo guided bone regeneration using aligned electrospun fibers.

    PubMed

    Lee, Ji-hye; Lee, Young Jun; Cho, Hyeong-jin; Shin, Heungsoo

    2014-08-01

    Tissue regeneration is a complex process in which numerous chemical and physical signals are coordinated in a specific spatiotemporal pattern. In this study, we tested our hypothesis that cell migration and bone tissue formation can be guided and facilitated by microscale morphological cues presented from a scaffold. We prepared poly(l-lactic acid) (PLLA) electrospun fibers with random and aligned structures and investigated their effect on in vitro migration of human mesenchymal stem cells (hMSCs) and in vivo bone growth using a critical-sized defect model. Using a polydopamine coating on the fibers, we compared the synergistic effects of chemical signals. The adhesion morphology of hMSCs was consistent with the direction of fiber alignment, whereas the proliferation of hMSCs was not affected. The orientation of fibers profoundly affected cell migration, in which hMSCs cultured on aligned fibers migrated 10.46-fold faster along the parallel direction than along the perpendicular direction on polydopamine-coated PLLA nanofibers. We implanted each fiber type into a mouse calvarial defect model for 2 months. The micro-computed tomography (CT) imaging demonstrated that regenerated bone area was the highest when mice were implanted with aligned fibers with polydopamine coating, indicating a positive synergistic effect on bone regeneration. More importantly, scanning electron microscopy microphotographs revealed that the direction of regenerated bone tissue appeared to be consistent with the direction of the implanted fibers, and transmission electron microscopy images showed that the orientation of collagen fibrils appeared to be overlapped along the direction of nanofibers. Taken together, our results demonstrate that the aligned nanofibers can provide spatial guidance for in vitro cell migration as well as in vivo bone regeneration, which may be incorporated as major instructive cues for the stimulation of tissue regeneration.

  4. Gravitational Loading Stimulates Adhesion of Satellite Cells and Myonuclear Accretion During Fiber Growth in Rat Soleus Muscle

    NASA Astrophysics Data System (ADS)

    Kawano, Fuminori; Wang, Xiao Dong; Nakai, Naoya; Higo, Yoko; Terada, Masahiro; Ohira, Takashi; Nonaka, Ikuya; Ohira, Yoshinobu

    2008-06-01

    Effects of gravitational loading on the growth-associated increase in the soleus muscle mass of rats were studied. New-born pups were hindlimb-unloaded from postnatal day 4 to month 3. The pups were returned to their dam for 1 hr after every 5 hrs of unloading. Such treatment was repeated until day 21, and the suspension was continuously performed thereafter. Control pups were also separated from their dam and followed the same feeding schedule. After 3 months of suspension, the suspension was terminated and ambulation recovery was allowed in the unloaded rats for 3 months. The sampling of soleus muscle was performed before and immediately, 1, 2, and 3 months after suspension. The fiber cross-sectional area and number of total muscle fibers, myonuclei, and satellite cells were measured in whole single muscle fibers sampled from tendon-to-tendon or cross-section of the muscle. The total fiber number was ~800 at day 4. The number was increased to ~2,500 after 3 months in both control and unloaded rats, suggesting that fiber formation is not load-dependent. Increase of fiber cross-sectional area during the first 3 months was ~69% less in the unloaded than the age-matched controls. Growth-related increases of the number of quiescent and mitotic active satellite cells were inhibited by unloading. The number of myonuclei was also less in the unloaded rats. However, all of these parameters, inhibited by unloading, were increased toward the control levels generally by reloading. These results suggest that the adhesion of satellite cells to growing muscle fibers and subsequent proliferation of satellite cells and accretion of myonuclei are load-dependent, although the formation of fibers might be genetically programmed.

  5. The importance of endometrial nerve fibers and macrophage cell count in the diagnosis of endometriosis

    PubMed Central

    Cetin, Cihan; Serdaroglu, Hasan; Tuzlali, Sitki

    2013-01-01

    Background: Endometriosis is a disease that is hard to diagnose without the gold standard method, laparoscopy. An easier diagnostic method is needed. Objective: The aim of the study is to determine whether the number of macrophage cells in the endometrium and/or the detection of nerve fibers can be used in the diagnosis of endometriosis. Materials and Methods: Endometrial sampling was done to 31 patients prior to laparoscopy (L/S) or laparotomy (L/T) at Istanbul University Istanbul School of Medicine Hospital between January 2010 February 2011. Also 34 patients who were retrospectively chosen from their files were added to the study. 5 patients were excluded from the study. Totally, 31 patients were placed in the endometriosis and 29 patients in the control group. Endometrial samples were evaluated immunohistochemically with the markers protein gene product 9.5 (PGP 9.5) and neurofilament (NF) for nerve fibers and CD68 for macrophages. Results: None of the samples were stained with PGP 9.5 and NF. As for CD68+cells, no statistically significant difference was observed between groups (endometriosis: 216.10±104.41; control: 175.93±43.05, p=0.06). Results were also evaluated in the subgroups of menstruel phases and disease stages. Only in the proliferative phase there was a significant increase in the endometriosis group (p=0.03). No significant difference was observed between the stages. Conclusion: The detection of nerve fibers in the eutopic endometrium with the markers of PGP 9.5 and NF is not found to be helpful in the diagnosis of endometriosis. Macrophage cells may be helpful in the diagnosis only in the proliferative phase. PMID:24639773

  6. Independent replication of mitochondrial genes supports the transcriptional program in developing fiber cells of cotton (Gossypium hirsutum L.).

    PubMed

    Thyssen, Gregory N; Song, Xianliang; Naoumkina, Marina; Kim, Hee-Jin; Fang, David D

    2014-07-01

    The mitochondrial genomes of flowering plants exist both as a "master circle" chromosome and as numerous subgenomic sublimons that are generated by intramolecular recombination. Differential stability or replication of these sublimons allows individual mitochondrial gene copy numbers to vary independently between different cell types and developmental stages. Our objective was to determine the relationship between mitochondrial gene copy number and transcript abundance in the elongating fiber cells of Upland cotton (Gossypium hirsutum L.). We compared RNA and DNA from cotton fiber cells at five developmental time points from early elongation through secondary cell wall thickening from the Ligon-lintless 2 (Li2) short fiber mutant and its wild type near isogenic line (NIL) DP5690. Mitochondrial gene copy number decreased from 3 to 8-DPA in the developing cotton fiber cells while transcript levels remained low. As secondary cell wall biosynthesis began in developing fibers, the expression levels and copy numbers of mitochondrial genes involved in energy production and respiration were up-regulated in wild type cotton DP5690. However, the short fiber mutant Li2, failed to increase expression of these genes, which include three subunits of ATP synthase, atp1, atp8 and atp9 and two cytochrome genes cox1 and cob. At the same time, Li2 failed to increase the copy numbers of these highly expressed genes. Surprisingly, we found that when mitochondrial genes were highly transcribed, they also had very high copy numbers. This observation suggests that in developing cotton fibers, increased mitochondrial sublimon replication may support increases in gene transcription.

  7. Development of a Micro-Fiber Nickel Electrode for Nickel-Hydrogen Cell

    NASA Technical Reports Server (NTRS)

    Britton, Doris L.

    1996-01-01

    The development of a high specific energy battery is one of the objectives of the lightweight nickel-hydrogen (NiH2) program at the NASA Lewis Research Center. The approach has been to improve the nickel electrode by continuing combined in-house and contract efforts to develop a more efficient and lighter weight electrode for the nickel-hydrogen fuel cell. Small fiber diameter nickel plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products and have an advantage of increased surface area available for the deposition of active materials. Initial tests include activation and capacity measurements at different discharge levels followed by half-cell cycle testing at 80 percent depth-of-discharge in a low Earth orbit regime. The electrodes that pass the initial tests are life cycle tested in a boiler plate nickel-hydrogen cell before flightweight designs are built and tested.

  8. Ultrafine polybenzimidazole (PBI) fibers. [separators for alkaline batteries and dfuel cells

    NASA Technical Reports Server (NTRS)

    Chenevey, E. C.

    1979-01-01

    Mats were made from ultrafine polybenzimidazole (PBI) fibers to provide an alternate to the use of asbestos as separators in fuel cells and alkaline batteries. To minimize distortion during mat drying, a process to provide a dry fibrid was developed. Two fibrid types were developed: one coarse, making mats for battery separators; the other fine, making low permeability matrices for fuel cells. Eventually, it was demonstrated that suitable mat fabrication techniques yielded fuel cell separators from the coarser alkaline battery fibrids. The stability of PBI mats to 45% KOH at 123 C can be increased by heat treatment at high temperatures. Weight loss data to 1000 hours exposure show the alkali resistance of the mats to be superior to that of asbestos.

  9. Development of a Micro-Fiber Nickel Electrode for Nickel-Hydrogen Cell

    NASA Technical Reports Server (NTRS)

    Britton, Doris L.

    1996-01-01

    The development of a high specific energy battery is one of the objectives of the lightweight nickel-hydrogen (NiH2) program at the NASA Lewis Research Center. The approach has been to improve the nickel electrode by continuing combined in-house and contract efforts to develop a more efficient and lighter weight electrode for the nickel-hydrogen fuel cell. Small fiber diameter nickel plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products and have an advantage of increased surface area available for the deposition of active materials. Initial tests include activation and capacity measurements at different discharge levels followed by half-cell cycle testing at 80 percent depth-of-discharge in a low Earth orbit regime. The electrodes that pass the initial tests are life cycle tested in a boiler plate nickel-hydrogen cell before flightweight designs are built and tested.

  10. Development of a micro-fiber nickel electrode for nickel-hydrogen cell

    NASA Technical Reports Server (NTRS)

    Britton, Doris L.

    1995-01-01

    Development of a high specific energy nickel electrode is the main goal of the lightweight nickel electrode program at the NASA Lewis Research Center. The approach has been to improve the nickel electrode by continuing combined in-house and contract efforts to develop a more efficient and lighter weight electrode for the nickel-hydrogen cell. Small fiber diameter nickel plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products and have an advantage of increased surface area available for the deposition of active material. Initial tests include activation and capacity measurements at different discharge levels followed by half-cell cycle testing at 80 percent depth-of-discharge in a low-Earth-orbit regime. The electrodes that pass the initial tests are life cycle-tested in a boiler plate nickel-hydrogen cell before flightweight designs are built and tested.

  11. Fabrication of Carbon Nanowalls on Carbon Fiber Paper for Fuel Cell Application

    NASA Astrophysics Data System (ADS)

    Hiramatsu, Mineo; Mitsuguchi, Shinji; Horibe, Takeyoshi; Kondo, Hiroki; Hori, Masaru; Kano, Hiroyuki

    2013-01-01

    Carbon nanowalls (CNWs) can be described as self-assembled, vertically standing, few-layered graphene sheet nanostructures. In order to demonstrate the usefulness of CNWs in fuel cell application, CNWs were directly grown on carbon fiber paper (CFP) using the inductively coupled plasma-enhanced chemical vapor deposition (ICP-CVD) method. Subsequently, highly dispersed platinum (Pt) nanoparticles were formed on the surface of CNWs using metal-organic chemical fluid deposition (MOCFD) employing a supercritical fluid (SCF). Moreover, a single proton exchange membrane (PEM) fuel cell unit using a Pt-supported CNW/CFP electrode was constructed, and its voltage-current characteristics were measured. This configuration ensures that all the supported Pt nanoparticles are in electrical contact with the external electrical circuit. Such a design would improve Pt utilization and potentially decrease Pt usage. Pt-supported CNWs grown on CFP will be well suited to the application in electrodes of fuel cells.

  12. Close Vicinity of PrP Expressing Cells (FDC) with Noradrenergic Fibers in Healthy Sheep Spleen

    PubMed Central

    Lezmi, S.; Hunsmann, G.; Baron, T.

    2001-01-01

    In naturally and experimentally occurring scrapie in sheep, prions invade the immune system and replicate in lymphoid organs. Here we analysed immunohistochemically, in seven spleens of 6-month-old healthy sheep, the nature of the cells expressing prion protein (PrP) potentially supporting prion replication, as well as their relationship with autonomic innervation. PrP was identified using either RB1 rabbit antiserum or 4F2 monoclonal antibody directed against AA 108–123 portion of the bovine and AA 79–92 of human prion protein respectively. Using double labelling analysis, we demonstrated that PrPc is expressed by follicular dendritic cells using a specific monoclonal antibody (CNA42). We also showed the close vicinity of these PrP expressing cells with noradrenergic fibers, using a polyclonal tyrosine hydroxylase antibody. Our results may help the study of the cellular requirements for the possible neuroinvasion from the spleen. PMID:11785673

  13. Registration of Charged Particles by Scintillating Fibers Coupled with μ-CELL SI APDG

    NASA Astrophysics Data System (ADS)

    Basharuli, N.; Bondarenko, G.; Bekenov, B.; Golovin, V.; Petrov, V.; Ponomarev, N.; Grigoriev, E.

    2002-11-01

    Silicon μ-cell Avalanche Photodiode operating in Geiger mode (APDG) was used to detect light produced in scintillating fibers of 1 mm diameter by electrons from a 90Sr-source and by α-particles from a 238Pu-source. This recently developed in mesa-technology square 1 mm2 APDG, consisting of 1370 μ-cells, has enhanced inter-cell optical isolation and individual quenching resistors. It showed at room temperature and low biasing voltages (45-47 V) very high gain (up to 106), low dark counting rates (below 3 × 105sec-1) and high detection efficiency for photons of green light (> 35%). Basic characteristics - internal gain, dark counting rate and average number of detected photoelectrons as a function of bias voltage were measured.

  14. High Intensity Training May Reverse the Fiber Type Specific Decline in Myogenic Stem Cells in Multiple Sclerosis Patients

    PubMed Central

    Farup, Jean; Dalgas, Ulrik; Keytsman, Charly; Eijnde, Bert O.; Wens, Inez

    2016-01-01

    Multiple sclerosis (MS) is associated with loss of skeletal muscle mass and function. The myogenic stem cells (satellite cells—SCs) are instrumental to accretion of myonuclei, but remain to be investigated in MS. The present study aimed to compare the SC and myonuclei content between MS patients (n = 23) and age matched healthy controls (HC, n = 18). Furthermore, the effects of 12 weeks of high intensity training on SC and myonuclei content were explored in MS. Muscle biopsies were obtained from m. Vastus Lateralis at baseline (MS and HC) and following 12 weeks of training (MS only). Frozen biopsies were sectioned followed by immunohistochemical analysis for fiber type specific SCs (Pax7+), myonuclei (MN) and central nuclei content and fiber cross-sectional area (fCSA) was quantified using ATPase histochemistry. At baseline the SCs per fiber was lower in type II compared to type I fibers in both MS (119%, p < 0.01) and HC (69%, p < 0.05), whereas the SCs per fCSA was lower in type II fibers compared to type I only in MS (72%, p < 0.05). No differences were observed in MN or central nuclei between MS and HC. Following training the type II fiber SCs per fiber and per fCSA in MS patients increased by 165% (p < 0.05) and 135% (p < 0.05), respectively. Furthermore, the type II fiber MN content tended (p = 0.06) to be increased by 35% following training. In conclusion, the SC content is lower in type II compared to type I fibers in both MS and HC. Furthermore, high intensity training was observed to selectively increase the SC and myonuclei content in type II fibers in MS patients. PMID:27303309

  15. Facilitation of granule cell epileptiform activity by mossy fiber-released zinc in the pilocarpine model of temporal lobe epilepsy.

    PubMed

    Timofeeva, Olga; Nadler, J Victor

    2006-03-17

    Recurrent mossy fiber synapses in the dentate gyrus of epileptic brain facilitate the synchronous firing of granule cells and may promote seizure propagation. Mossy fiber terminals contain and release zinc. Released zinc inhibits the activation of NMDA receptors and may therefore oppose the development of granule cell epileptiform activity. Hippocampal slices from rats that had experienced pilocarpine-induced status epilepticus and developed a recurrent mossy fiber pathway were used to investigate this possibility. Actions of released zinc were inferred from the effects of chelation with 1 mM calcium disodium EDTA (CaEDTA). When granule cell population bursts were evoked by mossy fiber stimulation in the presence of 6 mM K(+) and 30 microM bicuculline, CaEDTA slowed the rate at which evoked bursting developed, but did not change the magnitude of the bursts once they had developed fully. The effects of CaEDTA were then studied on the pharmacologically isolated NMDA receptor- and AMPA/kainate receptor-mediated components of the fully developed bursts. CaEDTA increased the magnitude of NMDA receptor-mediated bursts and reduced the magnitude of AMPA/kainate receptor-mediated bursts. CaEDTA did not affect the granule cell bursts evoked in slices from untreated rats by stimulating the perforant path in the presence of bicuculline and 6 mM K(+). These results suggest that zinc released from the recurrent mossy fibers serves mainly to facilitate the recruitment of dentate granule cells into population bursts.

  16. Fatigue and human umbilical cord stem cell seeding characteristics of calcium phosphate-chitosan-biodegradable fiber scaffolds.

    PubMed

    Zhao, Liang; Burguera, Elena F; Xu, Hockin H K; Amin, Nikhil; Ryou, Heon; Arola, Dwayne D

    2010-02-01

    Calcium phosphate cement (CPC) has in situ-setting ability and bioactivity, but the brittleness and low strength limit CPC to only non-load-bearing bone repairs. Human umbilical cord mesenchymal stem cells (hUCMSCs) can be harvested without an invasive procedure required for the commonly studied bone marrow MSCs. However, little has been reported on hUCMSC delivery via bioactive scaffolds for bone tissue engineering. The objectives of this study were to develop CPC scaffolds with improved resistance to fatigue and fracture, and to investigate hUCMSC delivery for bone tissue engineering. In fast fracture, CPC with 15% chitosan and 20% polyglactin fibers (CPC-chitosan-fiber scaffold) had flexural strength of 26mPa, higher than 10mPa for CPC control (p<0.05). In cyclic loading, CPC-chitosan-fiber specimens that survived 2x10(6) cycles had the maximum stress of 10MPa, compared to 5MPa of CPC control. CPC-chitosan-fiber specimens that failed after multiple cycles had a mean stress-to-failure of 9MPa, compared to 5.8MPa for CPC control (p<0.05). hUCMSCs showed excellent viability when seeded on CPC and CPC-chitosan-fiber scaffolds. The percentage of live cells reached 96-99%. Cell density was about 300cells/mm(2) at day 1; it proliferated to 700cells/mm(2) at day 4. Wst-1 assay showed that the stronger CPC-chitosan-fiber scaffold had hUCMSC viability that matched the CPC control (p>0.1). In summary, this study showed that chitosan and polyglactin fibers substantially increased the fatigue resistance of CPC, and that hUCMSCs had excellent proliferation and viability on the scaffolds.

  17. Phagosomal pH and glass fiber dissolution in cultured nasal epithelial cells and alveolar macrophages: a preliminary study.

    PubMed Central

    Johnson, N F

    1994-01-01

    The dissolution rate of glass fibers has been shown to be pH sensitive using in vitro lung fluid simulant models. The current study investigated whether there is a difference in phagosomal pH (ppH) between rat alveolar macrophages (AM) and rat nasal epithelial cells (RNEC) and whether such a difference would influence the dissolution of glass fibers. The ppH was measured in cultured AM and RNEC using flow cytometric, fluorescence-emission rationing techniques with fluorescein-labeled, amorphous silica particles. Glass fiber dissolution was determined in AM and RNEC cultured for 3 weeks with fast dissolving glass fibers (GF-A) or slow dissolving ones (GF-B). The mean diameters of GF-A were 2.7 microns and of GF-B, 2.6 microns, the average length of both fibers was approximately 22 to 25 microns. Dissolution was monitored by measuring the length and diameter of intracellular fibers and estimating the volume, assuming a cylindrical morphology. The ppH of AM was 5.2 to 5.8, and the ppH of RNEC was 7.0 to 7.5. The GF-A dissolved more slowly in RNEC than in AM, and no dissolution was evident in either cell type with GF-B. The volume loss with GF-A after a 3-week culture with AM was 66% compared to 45% for cultured RNEC. These results are different from those obtained using in vitro lung fluid-simulant models where dissolution is faster at higher pH. This difference suggests that dissolution rates of glass fibers in AM should not be applied to the dissolution of fibers in epithelial cells. Images Figure 1. a Figure 1. b Figure 2. a Figure 2. b Figure 3. a Figure 3. b PMID:7882965

  18. Transgenic Expression of AQP1 in the Fiber Cells of AQP0 Knockout Mouse: Effects on Lens Transparency

    PubMed Central

    Varadaraj, K.; Kumari, S.S.; Mathias, R.T.

    2010-01-01

    Mutations and knockout of aquaporin 0 (AQP0) result in dominant lens cataract. To date, several functions have been proposed for AQP0; however, two functions, water permeability and cell-to-cell adhesion have been supported by several investigators and only water channel function has been readily authenticated by in vitro and ex vivo studies. Lens shifts protein expression from the more efficient AQP1 in the equatorial epithelial cells to the less efficient water channel, AQP0, in the differentiating secondary fiber cells; perhaps, AQP0 performs a distinctive function. If AQP0 has only water permeability function, can the more efficient water channel AQP1 transgenically expressed in the fiber cells compensate and restore lens transparency in the AQP0 knockout (AQP0-/-) mouse? To investigate, we generated a transgenic wild type mouse line expressing AQP1 in the fiber cells using αA-crystallin promoter. These transgenic mice (TgAQP1+/+) showed increase in fiber cell membrane water permeability without any morphological, anatomical or physiological defects compared to the wild type indicating that the main purpose of the shift in expression from AQP1 to AQP0 may not be to lessen the membrane water permeability. Further, we transgenically expressed AQP1 in the lens fiber cells of AQP0 knockout mouse (TgAQP1+/+/AQP0-/-) to determine whether AQP1 could restore AQP0 water channel function and regain lens transparency. Fiber cells of these mice showed 2.6 times more water permeability than the wild type. Transgene AQP1 reduced the severity of lens cataract and prevented dramatic acceleration of cataractogenesis. However, lens fiber cells showed deformities and lack of compact cellular architecture. Loss of lens transparency due to the absence of AQP0 was not completely restored indicating an additional function for AQP0. In vitro studies showed that AQP0 is capable of cell-to-cell adhesion while AQP1 is not. To our knowledge, this is the first report which uses an animal

  19. Regulation of the muscle fiber microenvironment by activated satellite cells during hypertrophy.

    PubMed

    Fry, Christopher S; Lee, Jonah D; Jackson, Janna R; Kirby, Tyler J; Stasko, Shawn A; Liu, Honglu; Dupont-Versteegden, Esther E; McCarthy, John J; Peterson, Charlotte A

    2014-04-01

    Our aim in the current study was to determine the necessity of satellite cells for long-term muscle growth and maintenance. We utilized a transgenic Pax7-DTA mouse model, allowing for the conditional depletion of > 90% of satellite cells with tamoxifen treatment. Synergist ablation surgery, where removal of synergist muscles places functional overload on the plantaris, was used to stimulate robust hypertrophy. Following 8 wk of overload, satellite cell-depleted muscle demonstrated an accumulation of extracellular matrix (ECM) and fibroblast expansion that resulted in reduced specific force of the plantaris. Although the early growth response was normal, an attenuation of hypertrophy measured by both muscle wet weight and fiber cross-sectional area occurred in satellite cell-depleted muscle. Isolated primary myogenic progenitor cells (MPCs) negatively regulated fibroblast ECM mRNA expression in vitro, suggesting a novel role for activated satellite cells/MPCs in muscle adaptation. These results provide evidence that satellite cells regulate the muscle environment during growth.

  20. Adhesion and migration of ovarian cancer cells on crosslinked laminin fibers nanofabricated by multiphoton excited photochemistry

    PubMed Central

    Chen, Xiyi; Brewer, Molly A.; Zou, Changping; Campagnola, Paul J.

    2013-01-01

    Ovarian cancer is the deadliest gynecological cancer, which may arise in part due to the concurrent invasion and metastasis of high grade tumors. It is thus crucial to gain insight into the adhesion and migration mechanisms in vivo, as this may ultimately lead to new treatment/detection options. To explore this possibility, we have used multiphoton excited photochemistry (MPE) to synthesize models of the ovarian basal lamina consisting of crosslinked laminin nanofibers to quantify the adhesion/migration dynamics. The nanostructured laminin patterns permit the systematic comparison of total migration, directed migration, adhesion, and morphology of “normal” immortalized human ovarian epithelial cells (IOSE) and three lines of varying metastatic potential (OVCA433, SKOV-3.ip1, and HEY-1 cells). We find that the migration of all the cell lines is directed by the crosslinked fibers, and that the contact guidance enhances the total migration rates relative to monolayers. These rates increase with increasing metastatic potential, and the more invasive cells are less rigid and more weakly adhered to the nanofibers. The extent of directed migration also depends on the cell polarity and focal adhesion expression. For the invasive cells, these findings are similar to the integrin-independent ameboid-like migration seen for polar cells in collagen gels. Collectively, the results suggest that contact mediated migration as well as decreased adhesion may be operative in metastasis of ovarian cancer in vivo. PMID:20023757

  1. Polypropylene hollow fiber for cells isolation: methods for evaluation of diffusive transport and quality of cells encapsulation.

    PubMed

    Granicka, Ludomira H; Kawiak, Jerzy; Snochowski, Marek; Wójcicki, Jan M; Sabalińska, Stanisława; Weryński, Andrzej

    2003-08-01

    Formulation of membrane properties is important prior the successful implantation of encapsulated cells producing therapeutically relevant compounds. The purpose of our study was to specify the methods allowing preliminary evaluation of hollow fibers (HF) chosen for immunoisolation. We have selected as estimates (1) diffusive permeability for small and large solutes, and HF cut off (in vitro), (2) histological evaluation of tissue overgrowth after sc. implantation into mice. It was found that diffusive coefficients were linearly dependent on the particle diameter except that of albumin (2-3 times higher than theoretically estimated). This discrepancy imply that for certain particles the interaction with membrane material may be significant. The histological evaluation showed that siliconized HF implanted for 105 days were accepted (there was thin fibrotic layer on the external surface of the HF, no surrounding haemopoietic cells were found). It is concluded that proposed methods for preliminary evaluation of hollow fibers chosen for immunoisolation seems to be reliable and suitable for testing diffusive permeability of each relevant cell product.

  2. A method to integrate patterned electrospun fibers with microfluidic systems to generate complex microenvironments for cell culture applications

    PubMed Central

    Wallin, Patric; Zandén, Carl; Carlberg, Björn; Hellström Erkenstam, Nina; Liu, Johan; Gold, Julie

    2012-01-01

    The properties of a cell’s microenvironment are one of the main driving forces in cellular fate processes and phenotype expression invivo. The ability to create controlled cell microenvironments invitro becomes increasingly important for studying or controlling phenotype expression in tissue engineering and drug discovery applications. This includes the capability to modify material surface properties within well-defined liquid environments in cell culture systems. One successful approach to mimic extra cellular matrix is with porous electrospun polymer fiber scaffolds, while microfluidic networks have been shown to efficiently generate spatially and temporally defined liquid microenvironments. Here, a method to integrate electrospun fibers with microfluidic networks was developed in order to form complex cell microenvironments with the capability to vary relevant parameters. Spatially defined regions of electrospun fibers of both aligned and random orientation were patterned on glass substrates that were irreversibly bonded to microfluidic networks produced in poly-dimethyl-siloxane. Concentration gradients obtained in the fiber containing channels were characterized experimentally and compared with values obtained by computational fluid dynamic simulations. Velocity and shear stress profiles, as well as vortex formation, were calculated to evaluate the influence of fiber pads on fluidic properties. The suitability of the system to support cell attachment and growth was demonstrated with a fibroblast cell line. The potential of the platform was further verified by a functional investigation of neural stem cell alignment in response to orientation of electrospun fibers versus a microfluidic generated chemoattractant gradient of stromal cell-derived factor 1 alpha. The described method is a competitive strategy to create complex microenvironments invitro that allow detailed studies on the interplay of topography, substrate surface properties, and soluble

  3. Recurrent mossy fibers preferentially innervate parvalbumin-immunoreactive interneurons in the granule cell layer of the rat dentate gyrus.

    PubMed

    Blasco-Ibáñez, J M; Martínez-Guijarro, F J; Freund, T F

    2000-09-28

    Detection of vesicular zinc and immunohistochemistry against markers for different interneuron subsets were combined to study the postsynaptic target selection of zinc-containing recurrent mossy fiber collaterals in the dentate gyrus. Mossy fiber collaterals in the granule cell layer selectively innervated parvalbumin-containing cells, with numerous contacts per cell, whereas the granule cells were avoided. Under the electron microscope, those boutons made asymmetrical contacts on dendrites and somata. These findings suggest that, in addition to the hilar perforant path-associated (HIPP) interneurons, the basket and chandelier cells also receive a powerful feed-back drive from the granule cells, and thereby are able to control population synchrony in the dentate gyrus. On the other hand, the amount of monosynaptic excitatory feed-back among granule cells is shown to be negligible.

  4. Nuclear removal during terminal lens fiber cell differentiation requires CDK1 activity: appropriating mitosis-related nuclear disassembly

    PubMed Central

    Chaffee, Blake R.; Shang, Fu; Chang, Min-Lee; Clement, Tracy M.; Eddy, Edward M.; Wagner, Brad D.; Nakahara, Masaki; Nagata, Shigekazu; Robinson, Michael L.; Taylor, Allen

    2014-01-01

    Lens epithelial cells and early lens fiber cells contain the typical complement of intracellular organelles. However, as lens fiber cells mature they must destroy their organelles, including nuclei, in a process that has remained enigmatic for over a century, but which is crucial for the formation of the organelle-free zone in the center of the lens that assures clarity and function to transmit light. Nuclear degradation in lens fiber cells requires the nuclease DNase IIβ (DLAD) but the mechanism by which DLAD gains access to nuclear DNA remains unknown. In eukaryotic cells, cyclin-dependent kinase 1 (CDK1), in combination with either activator cyclins A or B, stimulates mitotic entry, in part, by phosphorylating the nuclear lamin proteins leading to the disassembly of the nuclear lamina and subsequent nuclear envelope breakdown. Although most post-mitotic cells lack CDK1 and cyclins, lens fiber cells maintain these proteins. Here, we show that loss of CDK1 from the lens inhibited the phosphorylation of nuclear lamins A and C, prevented the entry of DLAD into the nucleus, and resulted in abnormal retention of nuclei. In the presence of CDK1, a single focus of the phosphonuclear mitotic apparatus is observed, but it is not focused in CDK1-deficient lenses. CDK1 deficiency inhibited mitosis, but did not prevent DNA replication, resulting in an overall reduction of lens epithelial cells, with the remaining cells possessing an abnormally large nucleus. These observations suggest that CDK1-dependent phosphorylations required for the initiation of nuclear membrane disassembly during mitosis are adapted for removal of nuclei during fiber cell differentiation. PMID:25139855

  5. Nuclear removal during terminal lens fiber cell differentiation requires CDK1 activity: appropriating mitosis-related nuclear disassembly.

    PubMed

    Chaffee, Blake R; Shang, Fu; Chang, Min-Lee; Clement, Tracy M; Eddy, Edward M; Wagner, Brad D; Nakahara, Masaki; Nagata, Shigekazu; Robinson, Michael L; Taylor, Allen

    2014-09-01

    Lens epithelial cells and early lens fiber cells contain the typical complement of intracellular organelles. However, as lens fiber cells mature they must destroy their organelles, including nuclei, in a process that has remained enigmatic for over a century, but which is crucial for the formation of the organelle-free zone in the center of the lens that assures clarity and function to transmit light. Nuclear degradation in lens fiber cells requires the nuclease DNase IIβ (DLAD) but the mechanism by which DLAD gains access to nuclear DNA remains unknown. In eukaryotic cells, cyclin-dependent kinase 1 (CDK1), in combination with either activator cyclins A or B, stimulates mitotic entry, in part, by phosphorylating the nuclear lamin proteins leading to the disassembly of the nuclear lamina and subsequent nuclear envelope breakdown. Although most post-mitotic cells lack CDK1 and cyclins, lens fiber cells maintain these proteins. Here, we show that loss of CDK1 from the lens inhibited the phosphorylation of nuclear lamins A and C, prevented the entry of DLAD into the nucleus, and resulted in abnormal retention of nuclei. In the presence of CDK1, a single focus of the phosphonuclear mitotic apparatus is observed, but it is not focused in CDK1-deficient lenses. CDK1 deficiency inhibited mitosis, but did not prevent DNA replication, resulting in an overall reduction of lens epithelial cells, with the remaining cells possessing an abnormally large nucleus. These observations suggest that CDK1-dependent phosphorylations required for the initiation of nuclear membrane disassembly during mitosis are adapted for removal of nuclei during fiber cell differentiation. © 2014. Published by The Company of Biologists Ltd.

  6. Asbestos-induced endothelial cell activation and injury. Demonstration of fiber phagocytosis and oxidant-dependent toxicity.

    PubMed

    Garcia, J G; Gray, L D; Dodson, R F; Callahan, K S

    1988-10-01

    Vascular endothelial cell injury is important in the development of a variety of chronic interstitial lung disorders. However, the involvement of such injury in the inflammatory response associated with the inhalation of asbestos fibers is unclear and the mechanism of asbestos fiber cytotoxicity remains unknown. In the present study, human umbilical vein endothelial cells were challenged with amosite asbestos and several parameters of cellular function were examined. Electron microscopic examination revealed that endothelial cell exposure to asbestos resulted in active phagocytosis of these particulates. Biochemical evidence of dose-dependent asbestos-mediated endothelial cell activation was indicated by increased metabolism of arachidonic acid. For example, amosite asbestos (500 micrograms/ml) produced a ninefold increase in prostacyclin (PGI2) levels over those levels in non-exposed cells. Incubation of human endothelial cells with asbestos fibers induced specific 51Cr release in both a dose- and time-dependent fashion indicative of cellular injury. Injury induced by amosite asbestos was not significantly attenuated by treatment of the endothelial cell monolayer with either the iron chelator deferoxamine, which prevents hydroxyl radical (.OH) formation, or by the superoxide anion (O2-) scavenger, superoxide dismutase. However, significant dose-dependent protection was observed with the hydrogen peroxide (H2O2) scavenger, catalase. Chelation of elemental iron present within amosite asbestos fibers by deferoxamine produced a 33% reduction in asbestos cytotoxicity, suggesting a potential role for hydroxyl radical-mediated injury via the iron-catalyzed Haber-Weiss reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Mineral fiber-induced malondialdehyde formation and effects of oxidant scavengers in phagocytic cells.

    PubMed

    Yano, E

    1988-01-01

    Malondialdehyde (MDA) is a product of free-radical reaction with lipids and has been implicated in a variety of pathological processes including inflammation and carcinogenesis. In order to document the toxic reactions related to the pathogenic mechanisms of mineral fibers, asbestos and other mineral dusts were examined for their potency to produce lipid peroxidation using the thiobarbital method for MDA measurement. Human peripheral blood-derived neutrophils (PMN), guinea pig peritoneal macrophages, and guinea pig alveolar lavage cells produced MDA when treated with crocidolite asbestos. Of the various mineral dusts tested, only crocidolite showed a significant increase of MDA production. The amount of MDA produced by PMN treated with crocidolite increased with milling the fiber and with the incubation time. Both superoxide dismutase (SOD) and catalase were examined for their ability to inhibit MDA formation. At concentrations of up to 50 micrograms/10(6) cells, SOD did not inhibit the MDA formation in macrophages. However, catalase at the same concentration inhibited MDA formation in macrophages completely. A possible mechanism of MDA formation and its relationship with superoxide production are discussed.

  8. Characteristics of boron doped mesophase pitch-based carbon fibers as anode materials for lithium secondary cells

    SciTech Connect

    Tamaki, Toshio; Kawamura, Toshifumi; Yamazaki, Yoshinori

    1998-07-01

    Mesophase pitch-based Carbon Fibers(MCF) have been investigated as anode materials for lithium secondary cells by examining their physical and electrochemical properties. Discharge capacity and initial charge-discharge efficiency of the materials were studied in relation to the heat treatment temperatures of MCF. MCF heat treated at about 3,000 C gave high discharge capacity over 310mAh/g, good efficiency (93%) and superior current capability of 600mA/g (6mA/cm2). On the other hand, to improve the battery capacity, Boron was doped to the fiber about several {degree} by adding B{sub 4}C to the pre-carbonized milled fibers and then heat-treated up to 3,000 C in Ar. Then heat treated at 2,500 C under vacuum condition to remove remained B{sub 4}C. The structure of Boron-doped fibers was characterized and compared with that of non-doped standard fibers, and also Li ion battery performances are evaluated. The Boron-doped MCF indicated improvement in graphitization and increased discharge capacity as high as 360mAh/g. The voltammograms of both fibers are different from each other. The cell mechanism is discussed based on the unique structure of Boron-doping to the MCF is very effective for the battery performance.

  9. Growth of ZnO nanowires on fibers for one-dimensional flexible quantum dot-sensitized solar cells.

    PubMed

    Chen, Haining; Zhu, Liqun; Liu, Huicong; Li, Weiping

    2012-02-24

    One-dimensional flexible solar cells were fabricated through vertical growth of ZnO nanowires on freestanding carbon fibers and subsequent deposition of CdS quantum dots (QDs). Under light illumination, excitons were generated in the CdS QDs and dissociated in the ZnO/CdS interface. Photoelectrochemical characterization indicates that fiber quantum dot-sensitized solar cells (QDSCs) could effectively absorb visible light and convert it to electric energy. The photoelectrochemical performance was enhanced after the deposition of a ZnS passivating layer on the CF/ZnO/CdS surface. The highest conversion efficiency of about 0.006% was achieved by the fiber QDSCs. A higher conversion efficiency was expected to be achieved after some important parameters and cell structure were optimized and improved.

  10. Self-powered textile for wearable electronics by hybridizing fiber-shaped nanogenerators, solar cells, and supercapacitors

    PubMed Central

    Wen, Zhen; Yeh, Min-Hsin; Guo, Hengyu; Wang, Jie; Zi, Yunlong; Xu, Weidong; Deng, Jianan; Zhu, Lei; Wang, Xin; Hu, Chenguo; Zhu, Liping; Sun, Xuhui; Wang, Zhong Lin

    2016-01-01

    Wearable electronics fabricated on lightweight and flexible substrate are believed to have great potential for portable devices, but their applications are limited by the life span of their batteries. We propose a hybridized self-charging power textile system with the aim of simultaneously collecting outdoor sunshine and random body motion energies and then storing them in an energy storage unit. Both of the harvested energies can be easily converted into electricity by using fiber-shaped dye-sensitized solar cells (for solar energy) and fiber-shaped triboelectric nanogenerators (for random body motion energy) and then further stored as chemical energy in fiber-shaped supercapacitors. Because of the all–fiber-shaped structure of the entire system, our proposed hybridized self-charging textile system can be easily woven into electronic textiles to fabricate smart clothes to sustainably operate mobile or wearable electronics. PMID:27819039

  11. Self-powered textile for wearable electronics by hybridizing fiber-shaped nanogenerators, solar cells, and supercapacitors.

    PubMed

    Wen, Zhen; Yeh, Min-Hsin; Guo, Hengyu; Wang, Jie; Zi, Yunlong; Xu, Weidong; Deng, Jianan; Zhu, Lei; Wang, Xin; Hu, Chenguo; Zhu, Liping; Sun, Xuhui; Wang, Zhong Lin

    2016-10-01

    Wearable electronics fabricated on lightweight and flexible substrate are believed to have great potential for portable devices, but their applications are limited by the life span of their batteries. We propose a hybridized self-charging power textile system with the aim of simultaneously collecting outdoor sunshine and random body motion energies and then storing them in an energy storage unit. Both of the harvested energies can be easily converted into electricity by using fiber-shaped dye-sensitized solar cells (for solar energy) and fiber-shaped triboelectric nanogenerators (for random body motion energy) and then further stored as chemical energy in fiber-shaped supercapacitors. Because of the all-fiber-shaped structure of the entire system, our proposed hybridized self-charging textile system can be easily woven into electronic textiles to fabricate smart clothes to sustainably operate mobile or wearable electronics.

  12. Tensile properties of single stress fibers isolated from cultured vascular smooth muscle cells.

    PubMed

    Deguchi, Shinji; Ohashi, Toshiro; Sato, Masaaki

    2006-01-01

    Stress fibers (SFs), a contractile bundle of actin filaments, play a critical role in mechanotransduction in adherent cells; yet, the mechanical properties of SFs are poorly understood. Here, we measured tensile properties of single SFs by in vitro manipulation with cantilevers. SFs were isolated from cultured vascular smooth muscle cells with a combination of low ionic-strength extraction and detergent extraction and were stretched until breaking. The breaking force and the Young's modulus (assuming that SFs were isotropic) were, on average, 377 nN and 1.45 MPa, which were approximately 600-fold greater and three orders of magnitude lower, respectively, than those of actin filaments reported previously. Strain-induced stiffening was observed in the force-strain curve. We also found that the extracted SFs shortened to approximately 80% of the original length in an ATP-independent manner after they were dislodged from the substrate, suggesting that SFs had preexisting strain in the cytoplasm. The force required for stretching the single SFs from the zero-stress length back to the original length was approximately 10 nN, which was comparable with the traction force level applied by adherent cells at single adhesion sites to maintain cell integrity. These results suggest that SFs can bear intracellular stresses that may affect overall cell mechanical properties and will impact interpretation of intracellular stress distribution and force-transmission mechanism in adherent cells.

  13. Mixed Electrical-Chemical Transmission between Hippocampal Mossy Fibers and Pyramidal Cells

    PubMed Central

    Vivar, Carmen; Traub, Roger D.; Gutiérrez, Rafael

    2011-01-01

    Morphological and electrophysiological studies have shown that granule cell axons, the mossy fibers (MFs), establish gap junctions and, therefore, electrical communication among them. That granule cells express gap junctional proteins in their axons suggests the possibility that their terminals express them as well. If this were to be the case, mixed electrical-chemical communication could be supported, as MF terminals normally use glutamate for fast communication with their target cells. Here we present electrophysiological and modeling studies consistent with this hypothesis. We show that MF activation produced fast spikelets followed by excitatory postsynaptic potentials in pyramidal cells (PCs), which, unlike the spikelets, underwent frequency potentiation and were strongly depressed by activation of metabotropic glutamate receptors, as expected from transmission of MF origin. The spikelets, which persisted during blockade of chemical transmission, wee potentiated by dopamine and suppressed by the gap junction blocker carbenoxolone. The various waveforms evoked by MF stimulation were replicated in a multi-compartment model of a PC by brief current pulse injections into the proximal apical dendritic compartment, where MFs are known to contact PCs. Mixed electrical and glutamatergic communication between granule cells and some PCs in CA3 may ensure the activation of sets of PCs, bypassing the strong action of concurrent feed-forward inhibition that granule cells activate. Importantly, MF-to-PC electrical coupling may allow bidirectional, possibly graded communication that can be faster than chemical synapses and subject to different forms of modulation. PMID:22151275

  14. Enhanced proliferation and osteogenic differentiation of rat mesenchymal stem cells in collagen sponge reinforced with different poly(ethylene terephthalate) fibers.

    PubMed

    Takamoto, Tomoaki; Hiraoka, Yosuke; Tabata, Yasuhiko

    2007-01-01

    The objective of this study was to investigate the feasibility of collagen sponges mechanically reinforced by the incorporation of poly(ethylene terephthalate) (PET) fibers in stem cell culture. A collagen solution with homogeneously dispersed PET fibers was freeze-dried, followed by dehydrothermal cross-linking to obtain the collagen sponge incorporating PET fibers. By scanning electron microscopy observation, the collagen sponges exhibited isotropic and interconnected pore structures with an average size of 200 microm, irrespective of PET fiber incorporation. As expected, PET fibers incorporation significantly enhanced the compression strength of collagen sponge. When used for rat mesenchymal stem cells (MSC), the collagen sponge incorporating PET fibers was superior to the original collagen sponge without PET fibers incorporation in terms of the initial attachment, proliferation and osteogenic differentiation of cells, irrespective of the amount and diameter of fibers incorporated. The shrinkage of sponges during cell culture was significantly suppressed by the fiber incorporation. It is possible that the shrinkage suppression maintains the three-dimensional inner pore structure of collagen sponges without impairing the cell compatibility, resulting in the superior MSC attachment and the subsequent osteogenic differentiation in the sponge incorporating PET fiber.

  15. Rotation and deformation of human red blood cells with light from tapered fiber probes

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoshuai; Huang, Jianbin; Li, Yuchao; Zhang, Yao; Li, Baojun

    2016-08-01

    Dynamic rotation and deformation of human red blood cells (RBCs) are extremely important to investigate the survival and mechanical features of cells, which will be of great physiological and pathological significance. Here, we report an optical approach that is capable of both rotating and deforming RBCs with light from two tapered fiber probes (TFPs). With laser beams at the wavelength of 980 nm injected into the TFPs, a single RBC was rotated around different axes while single or multiple RBCs were stretched by adjusting the points of action and magnitude of the optical forces from the TFPs. The biological safety of the approach was also discussed by taking the laser power required into account.

  16. Rotation and deformation of human red blood cells with light from tapered fiber probes

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoshuai; Huang, Jianbin; Li, Yuchao; Zhang, Yao; Li, Baojun

    2017-01-01

    Dynamic rotation and deformation of human red blood cells (RBCs) are extremely important to investigate the survival and mechanical features of cells, which will be of great physiological and pathological significance. Here, we report an optical approach that is capable of both rotating and deforming RBCs with light from two tapered fiber probes (TFPs). With laser beams at the wavelength of 980 nm injected into the TFPs, a single RBC was rotated around different axes while single or multiple RBCs were stretched by adjusting the points of action and magnitude of the optical forces from the TFPs. The biological safety of the approach was also discussed by taking the laser power required into account.

  17. Impact of elastin incorporation into electrochemically aligned collagen fibers on mechanical properties and smooth muscle cell phenotype.

    PubMed

    Nguyen, Thuy-Uyen; Bashur, Chris A; Kishore, Vipuil

    2016-03-17

    Application of tissue-engineered vascular grafts (TEVGs) for the replacement of small-diameter arteries is limited due to thrombosis and intimal hyperplasia. Previous studies have attempted to address the limitations of TEVGs by developing scaffolds that mimic the composition (collagen and elastin) of native arteries to better match the mechanical properties of the graft with the native tissue. However, most existing scaffolds do not recapitulate the aligned topography of the collagen fibers found in native vessels. In the current study, based on the principles of isoelectric focusing, two different types of elastin (soluble and insoluble) were incorporated into highly oriented electrochemically aligned collagen (ELAC) fibers and the effect of elastin incorporation on the mechanical properties of the ELAC fibers and smooth muscle cell (SMC) phenotype was investigated. The results indicate that elastin incorporation significantly decreased the modulus of ELAC fibers to converge upon that of native vessels. Further, a significant increase in yield strain and decrease in Young's modulus was observed on all fibers post SMC culture compared with before the culture. Real-time polymerase chain reaction results showed a significant increase in the expression of α-smooth muscle actin and calponin on ELAC fibers with insoluble elastin, suggesting that incorporation of insoluble elastin induces a contractile phenotype in SMCs after two weeks of culture on ELAC fibers. Immunofluorescence results showed that calponin expression increased with time on all fibers. In conclusion, insoluble elastin incorporated ELAC fibers have the potential to be used for the development of functional TEVGs for the repair and replacement of small-diameter arteries.

  18. Muscle Fiber Characteristics, Satellite Cells and Soccer Performance in Young Athletes

    PubMed Central

    Metaxas, Thomas I.; Mandroukas, Athanasios; Vamvakoudis, Efstratios; Kotoglou, Kostas; Ekblom, Björn; Mandroukas, Konstantinos

    2014-01-01

    This study is aimed to examine the muscle fiber type, composition and satellite cells in young male soccer players and to correlate them to cardiorespiratory indices and muscle strength. The participants formed three Groups: Group A (n = 13), 11.2 ± 0.4yrs, Group B (n=10), 13.1 ± 0.5yrs and Group C (n = 9), 15.2 ± 0.6yrs. Muscle biopsies were obtained from the vastus lateralis. Peak torque values of the quadriceps and hamstrings were recorded and VO2max was measured on the treadmill. Group C had lower type I percentage distribution compared to A by 21.3% (p < 0.01), while the type IIA relative percentage was higher by 18.1% and 18.4% than in Groups A and B (p < 0.05). Groups B and C had higher cross-sectional area (CSA) values in all fiber types than in Group A (0.05 < p < 0.001). The number of satellite cells did not differ between the groups. Groups B and C had higher peak torque at all angular velocities and absolute VO2max in terms of ml·min-1 than Group A (0.05 < p < 0.001). It is concluded that the increased percentage of type IIA muscle fibers noticed in Group C in comparison to the Groups A and B should be mainly attributed to the different workload exercise and training programs. The alteration of myosin heavy chain (MHC) isoforms composition even in children is an important mechanism for skeletal muscle characteristics. Finally, CSA, isokinetic muscle strength and VO2max values seems to be expressed according to age. Key Points Fifteen years old soccer players have higher IIA percentage distribution than the younger players by approximately 18%. The age and the training status play a crucial role in muscle fibers co-expression. Specific training in young athletes seems to alter significantly the muscular metabolic profile. PMID:25177173

  19. "allometry" Deterministic Approaches in Cell Size, Cell Number and Crude Fiber Content Related to the Physical Quality of Kangkong (Ipomoea reptans) Grown Under Different Plant Density Pressures

    NASA Astrophysics Data System (ADS)

    Selamat, A.; Atiman, S. A.; Puteh, A.; Abdullah, N. A. P.; Mohamed, M. T. M.; Zulkeefli, A. A.; Othman, S.

    Kangkong, especially the upland type (Ipomoea reptans) is popularly consumed as a vegetable dish in the South East Asian countries for its quality related to Vitamins (A and C) and crude fiber contents. Higher fiber contents would prevent from the occurrence of colon cancer and diverticular disease. With young stem edible portion, its cell number and size contribute to the stem crude fiber content. The mathematical approach of allometry of cell size, number, and fiber content of stem could be used in determining the 'best' plant density pressure in producing the quality young stem to be consumed. Basically, allometry is the ratio of relative increment (growth or change) rates of two parameters, or the change rate associated to the log of measured variables relationship. Kangkog grown equal or lower than 55 plants m-2 produced bigger individual plant and good quality (physical) kangkong leafy vegetable, but with lower total yield per unit area as compared to those grown at higher densities.

  20. Cell division in Apicomplexan parasites is organized by a homolog of the striated rootlet fiber of algal flagella.

    PubMed

    Francia, Maria E; Jordan, Carly N; Patel, Jay D; Sheiner, Lilach; Demerly, Jessica L; Fellows, Justin D; de Leon, Jessica Cruz; Morrissette, Naomi S; Dubremetz, Jean-François; Striepen, Boris

    2012-01-01

    Apicomplexa are intracellular parasites that cause important human diseases including malaria and toxoplasmosis. During host cell infection new parasites are formed through a budding process that parcels out nuclei and organelles into multiple daughters. Budding is remarkably flexible in output and can produce two to thousands of progeny cells. How genomes and daughters are counted and coordinated is unknown. Apicomplexa evolved from single celled flagellated algae, but with the exception of the gametes, lack flagella. Here we demonstrate that a structure that in the algal ancestor served as the rootlet of the flagellar basal bodies is required for parasite cell division. Parasite striated fiber assemblins (SFA) polymerize into a dynamic fiber that emerges from the centrosomes immediately after their duplication. The fiber grows in a polarized fashion and daughter cells form at its distal tip. As the daughter cell is further elaborated it remains physically tethered at its apical end, the conoid and polar ring. Genetic experiments in Toxoplasma gondii demonstrate two essential components of the fiber, TgSFA2 and 3. In the absence of either of these proteins cytokinesis is blocked at its earliest point, the initiation of the daughter microtubule organizing center (MTOC). Mitosis remains unimpeded and mutant cells accumulate numerous nuclei but fail to form daughter cells. The SFA fiber provides a robust spatial and temporal organizer of parasite cell division, a process that appears hard-wired to the centrosome by multiple tethers. Our findings have broader evolutionary implications. We propose that Apicomplexa abandoned flagella for most stages yet retained the organizing principle of the flagellar MTOC. Instead of ensuring appropriate numbers of flagella, the system now positions the apical invasion complexes. This suggests that elements of the invasion apparatus may be derived from flagella or flagellum associated structures.

  1. Cotton GhMYB7 is predominantly expressed in developing fibers and regulates secondary cell wall biosynthesis in transgenic Arabidopsis.

    PubMed

    Huang, Junfeng; Chen, Feng; Wu, Siyu; Li, Juan; Xu, Wenliang

    2016-02-01

    The secondary cell wall in mature cotton fibers contains over 90% cellulose with low quantities of xylan and lignin. However, little is known regarding the regulation of secondary cell wall biosynthesis in cotton fibers. In this study, we characterized an R2R3-MYB transcription factor, GhMYB7, in cotton. GhMYB7 is expressed at a high level in developing fibers and encodes a MYB protein that is targeted to the cell nucleus and has transcriptional activation activity. Ectopic expression of GhMYB7 in Arabidopsis resulted in small, curled, dark green leaves and also led to shorter inflorescence stems. A cross-sectional assay of basal stems revealed that cell wall thickness of vessels and interfascicular fibers was higher in transgenic lines overexpressing GhMYB7 than in the wild type. Constitutive expression of GhMYB7 in Arabidopsis activated the expression of a suite of secondary cell wall biosynthesis-related genes (including some secondary cell wall-associated transcription factors), leading to the ectopic deposition of cellulose and lignin. The ectopic deposition of secondary cell walls may have been initiated before the cessation of cell expansion. Moreover, GhMYB7 was capable of binding to the promoter regions of AtSND1 and AtCesA4, suggesting that GhMYB7 may function upstream of NAC transcription factors. Collectively, these findings suggest that GhMYB7 is a potential transcriptional activator, which may participate in regulating secondary cell wall biosynthesis of cotton fibers.

  2. Modulation, Plasticity and Pathophysiology of the Parallel Fiber-Purkinje Cell Synapse

    PubMed Central

    Hoxha, Eriola; Tempia, Filippo; Lippiello, Pellegrino; Miniaci, Maria Concetta

    2016-01-01

    The parallel fiber-Purkinje cell (PF-PC) synapse represents the point of maximal signal divergence in the cerebellar cortex with an estimated number of about 60 billion synaptic contacts in the rat and 100,000 billions in humans. At the same time, the Purkinje cell dendritic tree is a site of remarkable convergence of more than 100,000 parallel fiber synapses. Parallel fiber activity generates fast postsynaptic currents via α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, and slower signals, mediated by mGlu1 receptors, resulting in Purkinje cell depolarization accompanied by sharp calcium elevation within dendritic regions. Long-term depression (LTD) and long-term potentiation (LTP) have been widely described for the PF-PC synapse and have been proposed as mechanisms for motor learning. The mechanisms of induction for LTP and LTD involve different signaling mechanisms within the presynaptic terminal and/or at the postsynaptic site, promoting enduring modification in the neurotransmitter release and change in responsiveness to the neurotransmitter. The PF-PC synapse is finely modulated by several neurotransmitters, including serotonin, noradrenaline and acetylcholine. The ability of these neuromodulators to gate LTP and LTD at the PF-PC synapse could, at least in part, explain their effect on cerebellar-dependent learning and memory paradigms. Overall, these findings have important implications for understanding the cerebellar involvement in a series of pathological conditions, ranging from ataxia to autism. For example, PF-PC synapse dysfunctions have been identified in several murine models of spino-cerebellar ataxia (SCA) types 1, 3, 5 and 27. In some cases, the defect is specific for the AMPA receptor signaling (SCA27), while in others the mGlu1 pathway is affected (SCA1, 3, 5). Interestingly, the PF-PC synapse has been shown to be hyper-functional in a mutant mouse model of autism spectrum disorder, with a selective deletion of Pten in

  3. [Changes in cell respiration of postural muscle fibers under long-term gravitational unloading after dietary succinate supplementation].

    PubMed

    Ogneva, I V; Veselova, O M; Larina, I M

    2011-01-01

    The intensity of cell respiration of the rat m. soleus, m. gastrocnemius c.m. and tibialis anterior fibers during 35-day gravitational unloading, with the addition of succinate in the diet at a dosage rate of 50 mg per 1 kg animal weight has been investigated. The gravitational unloading was modeled by antiorthostatic hindlimb suspension. The intensity of cell respiration was estimated by polarography. It was shown that the rate of oxygen consumption by soleus and gastrocnemius fibers on endogenous and exogenous substrates and with the addition of ADP decreases after the discharge. This may be associated with the transition to the glycolytic energy path due to a decrease in the EMG-activity. At the same time, the respiration rate after the addition of exogenous substrates in soleus fibers did not increase, indicating a disturbance in the function of the NCCR-section of the respiratory chain and more pronounced changes in the structure of muscle fibers. In tibialis anterior fibers, no changes in oxygen consumption velocity were observed. The introduction of succinate to the diet of rats makes it possible to prevent the negative effects of hypokinesia, although it reduces the basal level of intensity of cell respiration.

  4. Anisotropic Poly (glycerol sebacate)-Poly (ε-caprolactone) Electrospun Fibers Promote Endothelial Cell Guidance

    PubMed Central

    Gaharwar, Akhilesh K.; Nikkhah, Mehdi; Sant, Shilpa; Khademhosseini, Ali

    2015-01-01

    Topographical cell guidance is utilized to engineer highly organized and aligned cellular constructs for numerous tissue engineering applications. Recently, electrospun scaffolds fabricated using poly(glycerol sebacate) (PGS) and poly(ε-caprolactone) (PCL) have shown a great promise to support valvular interstitial cell functions for the development of tissue engineered heart valves. However, one of the major drawbacks of PGS-PCL scaffolds is the lack of control over cellular alignment. In this work we investigate the role of scaffold architecture on the endothelial cell alignment, proliferation and formation of organized cellular structures. In particular, PGS-PCL scaffolds with randomly oriented and highly aligned fibers with tunable mechanical properties were fabricated using electrospinning technique. After one week of culture, endothelial cells on the aligned scaffolds exhibit higher proliferation compared to those cultures on randomly oriented fibrous scaffolds. Furthermore, the endothelial cells reorganize in response to the topographical features of anisotropic scaffolds forming highly organize cellular constructs. Thus, the topographical contact guidance, provided by aligned PGS-PCL scaffolds, is envisioned to be useful in developing aligned cellular structures for vascular tissue engineering. PMID:25516556

  5. Anisotropic poly (glycerol sebacate)-poly (ϵ-caprolactone) electrospun fibers promote endothelial cell guidance.

    PubMed

    Gaharwar, Akhilesh K; Nikkhah, Mehdi; Sant, Shilpa; Khademhosseini, Ali

    2014-12-17

    Topographical cell guidance is utilized to engineer highly organized and aligned cellular constructs for numerous tissue engineering applications. Recently, electrospun scaffolds fabricated using poly(glycerol sebacate) (PGS) and poly(ϵ-caprolactone) (PCL) have shown a great promise to support valvular interstitial cell functions for the development of tissue engineered heart valves. However, one of the major drawbacks of PGS-PCL scaffolds is the lack of control over cellular alignment. In this work, we investigate the role of scaffold architecture on the endothelial cell alignment, proliferation and formation of organized cellular structures. In particular, PGS-PCL scaffolds with randomly oriented and highly aligned fibers with tunable mechanical properties were fabricated using electrospinning technique. After one week of culture, endothelial cells on the aligned scaffolds exhibited higher proliferation compared to those cultures on randomly oriented fibrous scaffolds. Furthermore, the endothelial cells reorganized in response to the topographical features of aligned scaffolds forming highly organized cellular constructs. Thus, topographical contact guidance, provided by aligned PGS-PCL scaffolds, is envisioned to be useful in developing cellular structures for vascular tissue engineering.

  6. Electrospun Collagen/Silk Tissue Engineering Scaffolds: Fiber Fabrication, Post-Treatment Optimization, and Application in Neural Differentiation of Stem Cells

    NASA Astrophysics Data System (ADS)

    Zhu, Bofan

    Biocompatible scaffolds mimicking the locally aligned fibrous structure of native extracellular matrix (ECM) are in high demand in tissue engineering. In this thesis research, unidirectionally aligned fibers were generated via a home-built electrospinning system. Collagen type I, as a major ECM component, was chosen in this study due to its support of cell proliferation and promotion of neuroectodermal commitment in stem cell differentiation. Synthetic dragline silk proteins, as biopolymers with remarkable tensile strength and superior elasticity, were also used as a model material. Good alignment, controllable fiber size and morphology, as well as a desirable deposition density of fibers were achieved via the optimization of solution and electrospinning parameters. The incorporation of silk proteins into collagen was found to significantly enhance mechanical properties and stability of electrospun fibers. Glutaraldehyde (GA) vapor post-treatment was demonstrated as a simple and effective way to tune the properties of collagen/silk fibers without changing their chemical composition. With 6-12 hours GA treatment, electrospun collagen/silk fibers were not only biocompatible, but could also effectively induce the polarization and neural commitment of stem cells, which were optimized on collagen rich fibers due to the unique combination of biochemical and biophysical cues imposed to cells. Taken together, electrospun collagen rich composite fibers are mechanically strong, stable and provide excellent cell adhesion. The unidirectionally aligned fibers can accelerate neural differentiation of stem cells, representing a promising therapy for neural tissue degenerative diseases and nerve injuries.

  7. Progressive Failure of a Unidirectional Fiber-Reinforced Composite Using the Method of Cells: Discretization Objective Computational Results

    NASA Technical Reports Server (NTRS)

    Pineda, Evan J.; Bednarcyk, Brett A.; Waas, Anthony M.; Arnold, Steven M.

    2012-01-01

    The smeared crack band theory is implemented within the generalized method of cells and high-fidelity generalized method of cells micromechanics models to capture progressive failure within the constituents of a composite material while retaining objectivity with respect to the size of the discretization elements used in the model. An repeating unit cell containing 13 randomly arranged fibers is modeled and subjected to a combination of transverse tension/compression and transverse shear loading. The implementation is verified against experimental data (where available), and an equivalent finite element model utilizing the same implementation of the crack band theory. To evaluate the performance of the crack band theory within a repeating unit cell that is more amenable to a multiscale implementation, a single fiber is modeled with generalized method of cells and high-fidelity generalized method of cells using a relatively coarse subcell mesh which is subjected to the same loading scenarios as the multiple fiber repeating unit cell. The generalized method of cells and high-fidelity generalized method of cells models are validated against a very refined finite element model.

  8. Electrospun Matrices for Pelvic Floor Repair: Effect of Fiber Diameter on Mechanical Properties and Cell Behavior.

    PubMed

    Vashaghian, Mahshid; Zandieh-Doulabi, Behrouz; Roovers, Jan-Paul; Smit, Theodoor Henri

    2016-12-01

    Electrospun matrices are proposed as an alternative for polypropylene meshes in reconstructive pelvic surgery. Here, we investigated the effect of fiber diameter on (1) the mechanical properties of electrospun poly (lactic-co-glycolic acid)-blended-poly(caprolactone) (PLGA/PCL) matrices; (2) cellular infiltration; and (3) the newly formed extracellular matrix (ECM) in vitro. We compared electrospun matrices with 1- and 8 μm fiber diameter and used nonporous PLGA/PCL films as controls. The 8-μm matrices were almost twice as stiff as the 1-μm matrices with 1.38 and 0.66 MPa, respectively. Matrices had the same ultimate tensile strength, but with 80% the 1-μm matrices were much more ductile than the 8-μm ones (18%). Cells infiltrated deeper into the matrices with larger pores, but cellular activity was comparable on both substrates. New ECM was deposited faster on the electrospun samples, but after 2 and 4 weeks the amount of collagen was comparable with that on nonporous films. The ECM deposited on the 1-μm matrices, and the nonporous film was about three times stiffer than the ECM found on the 8-μm matrices. Cell behavior in terms of myofibroblastic differentiation and remodeling was similar on the 1-μm matrices and nonporous films, in comparison to that on the 8-μm matrices. We conclude that electrospinning enhances the integration of host cells as compared with a nonporous film of the same material. The 1-μm matrices result in better mechanical behavior and qualitatively better matrix production than the 8-μm matrices, but with limited cellular infiltration. These data are useful for designing electrospun matrices for the pelvic floor.

  9. Online quantitative monitoring of live cell engineered cartilage growth using diffuse fiber-optic Raman spectroscopy.

    PubMed

    Bergholt, Mads S; Albro, Michael B; Stevens, Molly M

    2017-09-01

    Tissue engineering (TE) has the potential to improve the outcome for patients with osteoarthritis (OA). The successful clinical translation of this technique as part of a therapy requires the ability to measure extracellular matrix (ECM) production of engineered tissues in vitro, in order to ensure quality control and improve the likelihood of tissue survival upon implantation. Conventional techniques for assessing the ECM content of engineered cartilage, such as biochemical assays and histological staining are inherently destructive. Raman spectroscopy, on the other hand, represents a non-invasive technique for in situ biochemical characterization. Here, we outline current roadblocks in translational Raman spectroscopy in TE and introduce a comprehensive workflow designed to non-destructively monitor and quantify ECM biomolecules in large (>3 mm), live cell TE constructs online. Diffuse near-infrared fiber-optic Raman spectra were measured from live cell cartilaginous TE constructs over a 56-day culturing period. We developed a multivariate curve resolution model that enabled quantitative biochemical analysis of the TE constructs. Raman spectroscopy was able to non-invasively quantify the ECM components and showed an excellent correlation with biochemical assays for measurement of collagen (R(2) = 0.84) and glycosaminoglycans (GAGs) (R(2) = 0.86). We further demonstrated the robustness of this technique for online prospective analysis of live cell TE constructs. The fiber-optic Raman spectroscopy strategy developed in this work offers the ability to non-destructively monitor construct growth online and can be adapted to a broad range of TE applications in regenerative medicine toward controlled clinical translation. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  10. Fluorescence image-guided photodynamic therapy of cancer cells using a scanning fiber endoscope

    NASA Astrophysics Data System (ADS)

    Woldetensae, Mikias H.; Kirshenbaum, Mark R.; Kramer, Greg M.; Zhang, Liang; Seibel, Eric J.

    2013-03-01

    A scanning fiber endoscope (SFE) and the cancer biomarker 5-aminolevulinic acid (5-ALA) were used to fluorescently detect and destroy superficial cancerous lesions, while experimenting with different dosimetry levels for concurrent or sequential imaging and laser therapy. The 1.6-mm diameter SFE was used to fluorescently image a confluent monolayer of A549 human lung cancer cells from culture, previously administered with 5 mM solution of 5-ALA for 4 hours. Twenty hours after therapy, cell cultures were stained to distinguish between living and dead cells using a laser scanning confocal microscope. To determine relative dosimetry for photodynamic therapy (PDT), 405-nm laser illumination was varied from 1 to 5 minutes with power varying from 5 to 18 mW, chosen to compare equal amounts of energy delivered to the cell culture. The SFE produced 500-line images of fluorescence at 15 Hz using the red detection channel centered at 635 nm. The results show that PDT of A549 cancer cell monolayers using 405nm light for imaging and 5-ALAinduced PpIX therapy was possible using the same SFE system. Increased duration and power of laser illumination produced an increased area of cell death upon live/dead staining. The ultrathin and flexible SFE was able to direct PDT using wide-field fluorescence imaging of a monolayer of cultured cancer cells after uptaking 5-ALA. The correlation between light intensity and duration of PDT was measured. Increased length of exposure and decreased light intensity yields larger areas of cell death than decreased length of exposure with increased light intensity.

  11. Polyphosphazene functionalized polyester fiber matrices for tendon tissue engineering: in vitro evaluation with human mesenchymal stem cells.

    PubMed

    Peach, M Sean; James, Roshan; Toti, Udaya S; Deng, Meng; Morozowich, Nicole L; Allcock, Harry R; Laurencin, Cato T; Kumbar, Sangamesh G

    2012-08-01

    Poly[(ethyl alanato)(1)(p-methyl phenoxy)(1)] phosphazene (PNEA-mPh) was used to modify the surface of electrospun poly(ε-caprolactone) (PCL) nanofiber matrices having an average fiber diameter of 3000 ± 1700 nm for the purpose of tendon tissue engineering and augmentation. This study reports the effect of polyphosphazene surface functionalization on human mesenchymal stem cell (hMSC) adhesion, cell-construct infiltration, proliferation and tendon differentiation, as well as long term cellular construct mechanical properties. PCL fiber matrices functionalized with PNEA-mPh acquired a rougher surface morphology and led to enhanced cell adhesion as well as superior cell-construct infiltration when compared to smooth PCL fiber matrices. Long-term in vitro hMSC cultures on both fiber matrices were able to produce clinically relevant moduli. Both fibrous constructs expressed scleraxis, an early tendon differentiation marker, and a bimodal peak in expression of the late tendon differentiation marker tenomodulin, a pattern that was not observed in PCL thin film controls. Functionalized matrices achieved a more prominent tenogenic differentiation, possessing greater tenomodulin expression and superior phenotypic maturity according to the ratio of collagen I to collagen III expression. These findings indicate that PNEA-mPh functionalization is an efficient method for improving cell interactions with electrospun PCL matrices for the purpose of tendon repair.

  12. Graphene-coated carbon fiber cloth for flexible electrodes of glucose fuel cells

    NASA Astrophysics Data System (ADS)

    Hoshi, Kazuki; Muramatsu, Kazuo; Sumi, Hisato; Nishioka, Yasushiro

    2016-02-01

    In this work, we fabricated flexible electrodes for a miniaturized, simple structured, and flexible glucose biofuel cell (BFC) using a graphene-coated carbon fiber cloth (GCFC). The areas of the anode and cathode electrodes were 3 × 10 mm2. The anode area was coated with the enzyme glucose oxidase, and the cathode area was coated with the enzyme bilirubin oxidase. No ion-exchange film was needed because glucose oxidase selectively oxidizes glucose and bilirubin oxidase selectively reduces oxygen. The power density of the BFC with GCFC electrodes in a phosphate buffer solution of 200 mM glucose solution at room temperature was 34.3 µW/cm2 at 0.43 V. The power density of a BFC using carbon fiber cloth (CFC) without graphene modification was 18.5 µW/cm2 at 0.13 V. The BFC with the GCFC electrode continued to function longer than 24 h with a power density higher than 5 µW/cm2. These effects were attributed to the much larger effective surface areas of the GCFC electrodes that maintain more enzymes than those of the CFC electrodes.

  13. Comparison of infiltrated ceramic fiber paper and mica base compressive seals for planar solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Le, Shiru; Sun, Kening; Zhang, Naiqing; Shao, Yanbin; An, Maozhong; Fu, Qiang; Zhu, Xiaodong

    Solid oxide fuel cells using non-glass sealants have become increasingly common. In this paper, fumed silica infiltrated ceramic fiber paper with pre-compression was compared with plain and pre-compressed at 10 MPa hybrid mica as compressive seals. Leakage tests were measured under a 0.1-1.0 MPa compressive load with the pressure gradient varying from 2 to 15 kPa. The results demonstrated that the leakage rate of infiltrated fiber paper was 0.04 sccm cm -1 for a 10 kPa gradient, under 1.0 MPa compressive load, while for mica it was 0.60 and 0.63 sccm cm -1 which indicated that the infiltrated ceramic fiber paper showed a much lower leakage than mica. Long-term thermal cycling tests demonstrated that although the leakage of fumed silica infiltrated fiber paper was slightly higher than that of hybrid mica, it remained stable after 20 thermal cycles and no interlayer was needed. The mass loss of the fiber paper was 1.7 × 10 -2 mg cm -2 h -1 in a hydrogen environment at 1073 K for 200 h. The leakage of infiltrated fiber paper remained about 0.06 sccm cm -1 after reduction.

  14. Selective effects of a fiber chimeric conditionally replicative adenovirus armed with hep27 gene on renal cancer cell.

    PubMed

    Fang, Lin; Cheng, Qian; Liu, Wenshun; Zhang, Jie; Ge, Yan; Zhang, Qi; Li, Liantao; Liu, Junjie; Zheng, Junnian

    2016-06-02

    ASBTARCT Adenoviruses mediated cancer gene therapies are widely investigated and show a promising effect on cancer treatment. However, efficient gene transfer varies among different cancer cell lines based on the expression of coxsakie adenovirus receptor (CAR). Hep27, a member of dehydrogenase/reductase (SDR) family, can bind to Mdm2, resulting in the attenuation of Mdm2-mediated p53 degradation. Here we constructed a fiber chimeric adenovirus carrying hep27 gene (F5/35-ZD55-Hep27), in which the fiber protein of 5-serotype adenovirus (Ad5) was substituted by that of 35-serotype adenovirus (Ad35), aiming to facilitate the infection for renal cancer cells and develop the role of hep27 in cancer therapy. We evaluated the CAR and CD46 (a membrane cofactor protein for Ad35) expression in four kinds of renal cancer cells and assessed the relationship between receptors and infection efficiency. 5/35 fiber-modified adenovirus had a much promising infectivity compared with Ad5-based vector in renal cancer cells. F5/35-ZD55-Hep27 had enhanced antitumor activity against human renal cancer cells compared to the other groups. Further, hep27 mediated p53 and cleaved-PARP upregulation and mdm2 downregulation was involved and caused increased apoptosis. Moreover, F5/35-ZD55-Hep27 significantly suppressed tumor growth in subcutaneous renal cancer cell xenograft models. Our data demonstrated that 5/35 fiber-modified adenovirus F5/35-ZD55-Hep27 transferred into renal cancers efficiently and increased p53 to induce cancer cell apoptosis. Thus 5/35 fiber-modified adenoviral vector F5/35-ZD55-Hep27 might a promising vector and antitumor reagent for renal cancer gene therapy.

  15. Cytotoxicity, oxidative stress and genotoxicity induced by glass fibers on human alveolar epithelial cell line A549.

    PubMed

    Rapisarda, Venerando; Loreto, Carla; Ledda, Caterina; Musumeci, Giuseppe; Bracci, Massimo; Santarelli, Lory; Renis, Marcella; Ferrante, Margherita; Cardile, Venera

    2015-04-01

    Man-made vitreous fibers have been widely used as insulation material as asbestos substitutes; however their morphology and composition raises concerns. In 1988 the International Agency for Research on Cancer classified fiberglass, rock wool, slag wool, and ceramic fibers as Group 2B, i.e. possibly carcinogenic to humans. In 2002 it reassigned fiberglass, rock and slag wool, and continuous glass filaments to Group 3, not classifiable as carcinogenic to humans. The aim of this study was to verify the cytotoxic and genotoxic effects and oxidative stress production induced by in vitro exposure of human alveolar epithelial cells A549 to glass fibers with a predominant diameter <3 μm (97%) and length >5 μm (93%). A549 cells were incubated with 5, 50, or 100 μg/ml (2.1, 21, and 42 μg/cm(2), respectively) of glass fibers for 72 h. Cytotoxicity and DNA damage were tested by the MTT and the Comet assay, respectively. Oxidative stress was determined by measuring inducible nitric oxide synthase (iNOS) expression by Western blotting, production of nitric oxide (NO) with Griess reagent, and concentration of reactive oxygen species by fluorescent quantitative analysis with 2',7'-dichlorofluorescein-diacetate (DCFH-DA). The results showed that glass fiber exposure significantly reduced cell viability and increased DNA damage and oxidative stress production in a concentration-dependent manner, demonstrating that glass fibers exert cytotoxic and genotoxic effects related to increased oxidative stress on the human alveolar cell line A549. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. [Effects of acupuncture with different filiform needles on tissues, cells and collagenous fiber of fascia in acupoint area of rats].

    PubMed

    Li, Cheng; Chen, Bo; Hu, Tiehan; Chen, Lei

    2015-08-01

    To explore the effects of acupuncture with different filiform needles on structure of fascial connective tissues, cellular activity, arrangement and content of collagen fibers in acupoint area of rats. A total of 32 SD rats were randomly divided into a blank group, a thin needle group, a medium needle group and a thick needle group, 8 rats in each one. Except for the blank group, rats in the remaining groups were treated with horizontal acupuncture at "Zhongwan" (CV 12) towards Conception Vessel with different filiform needles, and twirling mild reinforcing-reducing method was applied, once a day. Rats in the blank group were treated with identical anesthesia, grasping and fixation. After 3-day intervention, the fascial connective tissue of acupoint area was collected. HE staining, immumohistochemical staining of proliferating cell nuclear antigen (PCNA) and MASSON staining were adopted to observe the morphology of fascial connective tissues, expression of PCNA in cells and arrangement and expression of collagenous fiber. After acupuncture in each group, the consistency of morphology of fascial connective tissues and arrangement of collagenous fiber were changed; the expression of PCNA protein in the fascial connective tissue in each group was significantly increased (P<0. 01, P<0. 05). The area distribution of collagenous fiber were changed, and that in the thin needle group was insignificantly increased compared with that in the blank group (P>0. 05), and that in the medium needle group and thick needle group were reduced compared with that in the blank group (both P<0. 05). Acupuncture with different filiform needles can change the local tissue morphology of acupoints, strengthen cell activity and adjust the exyression of collagenous fiber protein, which may be one of the cellular biomechanics principles of the acupuncture therapy's "regulating meridians" effects. However, the stimulation is produced by different fifiform needles, and the complex relationships

  17. Continuous rhamnolipid production using denitrifying Pseudomonas aeruginosa cells in hollow-fiber bioreactor.

    PubMed

    Pinzon, Neissa M; Cook, Aaron G; Ju, Lu-Kwang

    2013-01-01

    Rhamnolipids are high-value effective biosurfactants produced by Pseudomonas aeruginosa. Large-scale production of rhamnolipids is still challenging especially under free-cell aerobic conditions in which the highly foaming nature of the culture broth reduces the productivity of the process. Immobilized systems relying on oxygen as electron acceptor have been previously investigated but oxygen transfer limitation presents difficulties for continuous rhamnolipid production. A coupled system using immobilized cells and nitrate instead of oxygen as electron acceptor taking advantage of the ability of P. aeruginosa to perform nitrate respiration was evaluated. This denitrification-based immobilized approach based on a hollow-fiber setup eliminated the transfer limitation problems and was found suitable for continuous rhamnolipid production in a period longer than 1,500 h. It completely eliminated the foaming difficulties related to aerobic systems with a comparable specific productivity of 0.017 g/(g dry cells)-h and allowed easy recovery of rhamnolipids from the cell-free medium.

  18. Redox-filled Carbon-Fiber Microelectrodes for Single-Cell Exocytosis.

    PubMed

    Cox, Jonathan T; Gunderson, Christopher G; Zhang, Bo

    2013-09-01

    Carbon-fiber microelectrodes (CFEs) are the primary electroanalytical tool in single-cell exocytosis and in-vivo studies. Here we report a new study on the kinetic properties of electrolyte-filled CFEs in single-cell measurements and demonstrate that the addition of outer sphere redox species, such as Fe(CN)6(3-) and Ru(NH3)6(3+), in the backfill electrolyte solution can greatly enhance the kinetic response of CFEs. We show that at 750 mV, a voltage normally applied for detection of dopamine, the presence of fast outer sphere redox species in the backfilling solution significantly enhances the kinetic response of CFEs toward fast dopamine detection at single PC12 cells. Moreover, we also demonstrate that the use of Fe(CN)6(3-) in the backfilling solution has enabled direct measurement of dopamine at applied voltages as low as 200 mV. This kinetic enhancement is believed to be due to faster electron-transfer kinetics on the coupling pole as compared to the sluggish reduction of oxygen. We anticipate that such redox-filled CFE ultramicroelectrodes will find many useful applications in single cell exocytosis and in-vivo sensing.

  19. Sef is a negative regulator of fiber cell differentiation in the ocular lens.

    PubMed

    Newitt, Peter; Boros, Jessica; Madakashira, Bhavani P; Robinson, Michael L; Reneker, Lixing W; McAvoy, John W; Lovicu, Frank J

    2010-07-01

    Growth factor signaling, mediated via receptor tyrosine kinases (RTKs), needs to be tightly regulated in many developmental systems to ensure a physiologically appropriate biological outcome. At one level this regulation may involve spatially and temporally ordered patterns of expression of specific RTK signaling antagonists, such as Sef (similar expression to fgfs). Growth factors, notably FGFs, play important roles in development of the vertebrate ocular lens. FGF induces lens cell proliferation and differentiation at progressively higher concentrations and there is compelling evidence that a gradient of FGF signaling in the eye determines lens polarity and growth patterns. We have recently identified the presence of Sef in the lens, with strongest expression in the epithelial cells. Given the important role for FGFs in lens developmental biology, we employed transgenic mouse strategies to determine if Sef could be involved in regulating lens cell behaviour. Over-expressing Sef specifically in the lens of transgenic mice led to impaired lens and eye development that resulted in microphthalmia. Sef inhibited primary lens fiber cell elongation and differentiation, as well as increased apoptosis, consistent with a block in FGFR-mediated signaling during lens morphogenesis. These results are consistent with growth factor antagonists, such as Sef, being important negative regulators of growth factor signaling. Moreover, the lens provides a useful paradigm as to how opposing gradients of a growth factor and its antagonist could work together to determine and stabilise tissue patterning during development and growth.

  20. Osteogenic and osteoclastogenic differentiation of co-cultured cells in polylactic acid-nanohydroxyapatite fiber scaffolds.

    PubMed

    Morelli, Sabrina; Salerno, Simona; Holopainen, Jani; Ritala, Mikko; De Bartolo, Loredana

    2015-06-20

    The design of bone substitutes involves the creation of a microenvironment supporting molecular cross-talk between cells and scaffolds during tissue formation and remodelling. Bone remodelling process includes the cooperation of bone-building cells and bone-resorbing cells. In this paper we developed polylactic acid (PLA) and composite PLA-nanohydroxyapatite (nHA) scaffolds with 20 and 50wt.% of nHA by electrospinning technique to be used in bone tissue engineering. The developed scaffolds have different fiber diameter, porosity with interconnected pores and mechanical properties. Taking cues from the bone environment features we investigated the differentiation of human mesenchymal stem cells (hMSCs) from bone marrow in osteoblasts and the osteoclastogenesis in the developed scaffolds in homotypic and in co-culture up to 46 days. PLA and composite PLA-nHA scaffolds induced osteogenic and osteoclastogenic differentiation. Both osteoblasts and osteoclasts displayed high expression of specific markers (osteopontin, osteocalcin, RANK, RANKL) and functions such as secretion of ALP, cathepsin K and TRAP activity on composite scaffolds especially on PLA-nHA containing 20wt.% of nHA. The heterotypic interactions between osteoblasts and osteoclasts co-cultured in the developed scaffolds triggered their functional differentiation and activation.

  1. 3D cell culture and osteogenic differentiation of human bone marrow stromal cells plated onto jet-sprayed or electrospun micro-fiber scaffolds.

    PubMed

    Brennan, Meadhbh Á; Renaud, Audrey; Gamblin, Anne-Laure; D'Arros, Cyril; Nedellec, Steven; Trichet, Valerie; Layrolle, Pierre

    2015-08-04

    A major limitation of the 2D culture systems is that they fail to recapitulate the in vivo 3D cellular microenvironment whereby cell-cell and cell-extracellular matrix (ECM) interactions occur. In this paper, a biomaterial scaffold that mimics the structure of collagen fibers was produced by jet-spraying. This micro-fiber polycaprolactone (PCL) scaffold was evaluated for 3D culture of human bone marrow mesenchymal stromal cells (MSCs) in comparison with a commercially available electrospun scaffold. The jet-sprayed scaffolds had larger pore diameters, greater porosity, smaller diameter fibers, and more heterogeneous fiber diameter size distribution compared to the electrospun scaffolds. Cells on jet-sprayed constructs exhibited spread morphology with abundant cytoskeleton staining, whereas MSCs on electrospun scaffolds appeared less extended with fewer actin filaments. MSC proliferation and cell infiltration occurred at a faster rate on jet-sprayed compared to electrospun scaffolds. Osteogenic differentiation of MSCs and ECM production as measured by ALP, collagen and calcium deposition was superior on jet-sprayed compared to electrospun scaffolds. The jet-sprayed scaffold which mimics the native ECM and permits homogeneous cell infiltration is important for 3D in vitro applications such as bone cellular interaction studies or drug testing, as well as bone tissue engineering strategies.

  2. Study of the Peripheral Nerve Fibers Myelin Structure Changes during Activation of Schwann Cell Acetylcholine Receptors

    PubMed Central

    Verdiyan, Ekaterina E.; Allakhverdiev, Elvin S.; Maksimov, Georgy V.

    2016-01-01

    In the present paper we consider a new type of mechanism by which neurotransmitter acetylcholine (ACh) regulates the properties of peripheral nerve fibers myelin. Our data show the importance of the relationship between the changes in the number of Schwann cell (SC) acetylcholine receptors (AChRs) and the axon excitation (different intervals between action potentials (APs)). Using Raman spectroscopy, an effect of activation of SC AChRs on the myelin membrane fluidity was investigated. It was found, that ACh stimulates an increase in lipid ordering degree of the myelin lipids, thus providing evidence for specific role of the “axon-SC” interactions at the axon excitation. It was proposed, that during the axon excitation, the SC membrane K+- depolarization and the Ca2+—influx led to phospholipase activation or exocytosis of intracellular membrane vesicles and myelin structure reorganization. PMID:27455410

  3. Effects of long-term microgravitation exposure on cell respiration of the rat musculus soleus fibers.

    PubMed

    Veselova, O M; Ogneva, I V; Larina, I M

    2011-07-01

    Cell respiration of the m. soleus fibers was studied in Wistar rats treated with succinic acid and exposed to microgravitation for 35 days. The results indicated that respiration rates during utilization of endogenous and exogenous substrates and the maximum respiration rate decreased in animals subjected to microgravitation without succinate treatment. The respiration rate during utilization of exogenous substrate did not increase in comparison with that on endogenous substrates. Succinic acid prevented the decrease in respiration rate on endogenous substrates and the maximum respiration rate. On the other hand, the respiration rate on exogenous substrates was reduced in vivarium control rats receiving succinate in comparison with intact control group. That could indicate changed efficiency of complex I of the respiratory chain due to reciprocal regulation of the tricarbonic acid cycle.

  4. A Novel Isoform of Sucrose Synthase Is Targeted to the Cell Wall during Secondary Cell Wall Synthesis in Cotton Fiber[C][W][OA

    PubMed Central

    Brill, Elizabeth; van Thournout, Michel; White, Rosemary G.; Llewellyn, Danny; Campbell, Peter M.; Engelen, Steven; Ruan, Yong-Ling; Arioli, Tony; Furbank, Robert T.

    2011-01-01

    Sucrose (Suc) synthase (Sus) is the major enzyme of Suc breakdown for cellulose biosynthesis in cotton (Gossypium hirsutum) fiber, an important source of fiber for the textile industry. This study examines the tissue-specific expression, relative abundance, and temporal expression of various Sus transcripts and proteins present in cotton. A novel isoform of Sus (SusC) is identified that is expressed at high levels during secondary cell wall synthesis in fiber and is present in the cell wall fraction. The phylogenetic relationships of the deduced amino acid sequences indicate two ancestral groups of Sus proteins predating the divergence of monocots and dicots and that SusC sequences form a distinct branch in the phylogeny within the dicot-specific clade. The subcellular location of the Sus isoforms is determined, and it is proposed that cell wall-localized SusC may provide UDP-glucose for cellulose and callose synthesis from extracellular sugars. PMID:21757635

  5. Tmod1 and CP49 Synergize to Control the Fiber Cell Geometry, Transparency, and Mechanical Stiffness of the Mouse Lens

    PubMed Central

    Gokhin, David S.; Nowak, Roberta B.; Kim, Nancy E.; Arnett, Ernest E.; Chen, Albert C.; Sah, Robert L.; Clark, John I.; Fowler, Velia M.

    2012-01-01

    The basis for mammalian lens fiber cell organization, transparency, and biomechanical properties has contributions from two specialized cytoskeletal systems: the spectrin-actin membrane skeleton and beaded filament cytoskeleton. The spectrin-actin membrane skeleton predominantly consists of α2β2-spectrin strands interconnecting short, tropomyosin-coated actin filaments, which are stabilized by pointed-end capping by tropomodulin 1 (Tmod1) and structurally disrupted in the absence of Tmod1. The beaded filament cytoskeleton consists of the intermediate filament proteins CP49 and filensin, which require CP49 for assembly and contribute to lens transparency and biomechanics. To assess the simultaneous physiological contributions of these cytoskeletal networks and uncover potential functional synergy between them, we subjected lenses from mice lacking Tmod1, CP49, or both to a battery of structural and physiological assays to analyze fiber cell disorder, light scattering, and compressive biomechanical properties. Findings show that deletion of Tmod1 and/or CP49 increases lens fiber cell disorder and light scattering while impairing compressive load-bearing, with the double mutant exhibiting a distinct phenotype compared to either single mutant. Moreover, Tmod1 is in a protein complex with CP49 and filensin, indicating that the spectrin-actin network and beaded filament cytoskeleton are biochemically linked. These experiments reveal that the spectrin-actin membrane skeleton and beaded filament cytoskeleton establish a novel functional synergy critical for regulating lens fiber cell geometry, transparency, and mechanical stiffness. PMID:23144950

  6. Lipid-Protein Interactions in Plasma Membranes of Fiber Cells Isolated from the Human Eye Lens

    PubMed Central

    Raguz, Marija; Mainali, Laxman; O’Brien, William J.; Subczynski, Witold K.

    2014-01-01

    The protein content in human lens membranes is extremely high, increases with age, and is higher in the nucleus as compared with the cortex, which should strongly affect the organization and properties of the lipid bilayer portion of intact membranes. To assess these effects, the intact cortical and nuclear fiber cell plasma membranes isolated from human lenses from 41- to 60-year-old donors were studied using electron paramagnetic resonance spin-labeling methods. Results were compared with those obtained for lens lipid membranes prepared from total lipid extracts from human eyes of the same age group [Mainali,L., Raguz, M., O’Brien, W. J., and Subczynski, W. K. (2013) Biochim. Biophys. Acta]. Differences were considered to be mainly due to the effect of membrane proteins. The lipid-bilayer portions of intact membranes were significantly less fluid than lipid bilayers of lens lipid membranes, prepared without proteins. The intact membranes were found to contain three distinct lipid environments termed the bulk lipid domain, boundary lipid domain, and trapped lipid domain. However, the cholesterol bilayer domain, which was detected in cortical and nuclear lens lipid membranes, was not detected in intact membranes. The relative amounts of bulk and trapped lipids were evaluated. The amount of lipids in domains uniquely formed due to the presence of membrane proteins was greater in nuclear membranes than in cortical membranes. Thus, it is evident that the rigidity of nuclear membranes is greater than that of cortical membranes. Also the permeability coefficients for oxygen measured in domains of nuclear membranes were significantly lower than appropriate coefficients measured in cortical membranes. Relationships between the organization of lipids into lipid domains in fiber cells plasma membranes and the organization of membrane proteins are discussed. PMID:24486794

  7. Wet-laid soy fiber reinforced hydrogel scaffold: Fabrication, mechano-morphological and cell studies.

    PubMed

    Wood, Andrew T; Everett, Dominique; Budhwani, Karim I; Dickinson, Brenna; Thomas, Vinoy

    2016-06-01

    Among materials used in biomedical applications, hydrogels have received consistent linear growth in interest over the past decade due to their large water volume and saliency to the natural extracellular matrix. These materials are often limited due to their sub-optimal mechanical properties which are typically improved via chemical or physical crosslinking. Chemical crosslinking forms strong inter-polymer bonds but typically uses reagents that are cytotoxic while physical crosslinking is more temperamental to environmental changes but can be formed without these toxic reagents. In this study, we added a fiber-reinforcement phase to a poly(vinyl alcohol) (PVA) hydrogel formed through successive freezing-thawing cycles by incorporating a non-woven microfiber mat formed by the wet-lay process. By reinforcing the hydrogel with a wet-laid fibrous mat, the ultimate tensile strength and modulus increased from 0.11 ± 0.01 MPa and 0.17 ± 0.02 kPa to 0.24 ± 0.02 MPa and 5.76 ± 1.12 kPa, respectively. An increase in toughness and elongation was also found increasing from 2.52 ± 0.37 MPa to 25.6 ± 3.84 and 51.89 ± 5.16% to 111.16 ± 9.68%, respectively. The soy fibers were also found to induce minimal cytotoxicity with endothelial cell viability showing 96.51% ± 1.91 living cells after a 48 h incubation. This approach to hydrogel-reinforcement presents a rapid, tunable method by which hydrogels can attain increased mechanical properties without sacrificing their inherent biologically favorable properties.

  8. Lipid-protein interactions in plasma membranes of fiber cells isolated from the human eye lens.

    PubMed

    Raguz, Marija; Mainali, Laxman; O'Brien, William J; Subczynski, Witold K

    2014-03-01

    The protein content in human lens membranes is extremely high, increases with age, and is higher in the nucleus as compared with the cortex, which should strongly affect the organization and properties of the lipid bilayer portion of intact membranes. To assess these effects, the intact cortical and nuclear fiber cell plasma membranes isolated from human lenses from 41- to 60-year-old donors were studied using electron paramagnetic resonance spin-labeling methods. Results were compared with those obtained for lens lipid membranes prepared from total lipid extracts from human eyes of the same age group [Mainali, L., Raguz, M., O'Brien, W. J., and Subczynski, W. K. (2013) Biochim. Biophys. Acta]. Differences were considered to be mainly due to the effect of membrane proteins. The lipid-bilayer portions of intact membranes were significantly less fluid than lipid bilayers of lens lipid membranes, prepared without proteins. The intact membranes were found to contain three distinct lipid environments termed the bulk lipid domain, boundary lipid domain, and trapped lipid domain. However, the cholesterol bilayer domain, which was detected in cortical and nuclear lens lipid membranes, was not detected in intact membranes. The relative amounts of bulk and trapped lipids were evaluated. The amount of lipids in domains uniquely formed due to the presence of membrane proteins was greater in nuclear membranes than in cortical membranes. Thus, it is evident that the rigidity of nuclear membranes is greater than that of cortical membranes. Also the permeability coefficients for oxygen measured in domains of nuclear membranes were significantly lower than appropriate coefficients measured in cortical membranes. Relationships between the organization of lipids into lipid domains in fiber cells plasma membranes and the organization of membrane proteins are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. The Control of Single-Celled Cotton Fiber Elongation by Developmentally Reversible Gating of Plasmodesmata and Coordinated Expression of Sucrose and K+ Transporters and Expansin

    PubMed Central

    Ruan, Yong-Ling; Llewellyn, Danny J.; Furbank, Robert T.

    2001-01-01

    Each cotton fiber is a single cell that elongates to 2.5 to 3.0 cm from the seed coat epidermis within ∼16 days after anthesis (DAA). To elucidate the mechanisms controlling this rapid elongation, we studied the gating of fiber plasmodesmata and the expression of the cell wall–loosening gene expansin and plasma membrane transporters for sucrose and K+, the major osmotic solutes imported into fibers. Confocal imaging of the membrane-impermeant fluorescent solute carboxyfluorescein (CF) revealed that the fiber plasmodesmata were initially permeable to CF (0 to 9 DAA), but closed at ∼10 DAA and re-opened at 16 DAA. A developmental switch from simple to branched plasmodesmata was also observed in fibers at 10 DAA. Coincident with the transient closure of the plasmodesmata, the sucrose and K+ transporter genes were expressed maximally in fibers at 10 DAA with sucrose transporter proteins predominately localized at the fiber base. Consequently, fiber osmotic and turgor potentials were elevated, driving the rapid phase of elongation. The level of expansin mRNA, however, was high at the early phase of elongation (6 to 8 DAA) and decreased rapidly afterwards. The fiber turgor was similar to the underlying seed coat cells at 6 to 10 DAA and after 16 DAA. These results suggest that fiber elongation is initially achieved largely by cell wall loosening and finally terminated by increased wall rigidity and loss of higher turgor. To our knowledge, this study provides an unprecedented demonstration that the gating of plasmodesmata in a given cell is developmentally reversible and is coordinated with the expression of solute transporters and the cell wall–loosening gene. This integration of plasmodesmatal gating and gene expression appears to control fiber cell elongation. PMID:11158528

  10. Macrophage deficiency in osteopetrotic (op/op) mice inhibits activation of satellite cells and prevents hypertrophy in single soleus fibers.

    PubMed

    Ohira, T; Wang, X D; Ito, T; Kawano, F; Goto, K; Izawa, T; Ohno, H; Kizaki, T; Ohira, Y

    2015-05-15

    Effects of macrophage on the responses of soleus fiber size to hind limb unloading and reloading were studied in osteopetrotic homozygous (op/op) mice with inactivated mutation of macrophage colony-stimulating factor (M-CSF) gene and in wild-type (+/+) and heterozygous (+/op) mice. The basal levels of mitotically active and quiescent satellite cell (-46 and -39% vs. +/+, and -40 and -30% vs. +/op) and myonuclear number (-29% vs. +/+ and -28% vs. +/op) in fibers of op/op mice were significantly less than controls. Fiber length and sarcomere number in op/op were also less than +/+ (-22%) and +/op (-21%) mice. Similar trend was noted in fiber cross-sectional area (CSA, -15% vs. +/+, P = 0.06, and -14% vs. +/op, P = 0.07). The sizes of myonuclear domain, cytoplasmic volume per myonucleus, were identical in all types of mice. The CSA, length, and the whole number of sarcomeres, myonuclei, and mitotically active and quiescent satellite cells, as well as myonuclear domain, in single muscle fibers were decreased after 10 days of unloading in all types of mice, although all of these parameters in +/+ and +/op mice were increased toward the control values after 10 days of reloading. However, none of these levels in op/op mice were recovered. Data suggest that M-CSF and/or macrophages are important to activate satellite cells, which cause increase of myonuclear number during fiber hypertrophy. However, it is unclear why their responses to general growth and reloading after unloading are different.

  11. Human proximal tubule epithelial cells cultured on hollow fibers: living membranes that actively transport organic cations.

    PubMed

    Jansen, J; De Napoli, I E; Fedecostante, M; Schophuizen, C M S; Chevtchik, N V; Wilmer, M J; van Asbeck, A H; Croes, H J; Pertijs, J C; Wetzels, J F M; Hilbrands, L B; van den Heuvel, L P; Hoenderop, J G; Stamatialis, D; Masereeuw, R

    2015-11-16

    The bioartificial kidney (BAK) aims at improving dialysis by developing 'living membranes' for cells-aided removal of uremic metabolites. Here, unique human conditionally immortalized proximal tubule epithelial cell (ciPTEC) monolayers were cultured on biofunctionalized MicroPES (polyethersulfone) hollow fiber membranes (HFM) and functionally tested using microfluidics. Tight monolayer formation was demonstrated by abundant zonula occludens-1 (ZO-1) protein expression along the tight junctions of matured ciPTEC on HFM. A clear barrier function of the monolayer was confirmed by limited diffusion of FITC-inulin. The activity of the organic cation transporter 2 (OCT2) in ciPTEC was evaluated in real-time using a perfusion system by confocal microscopy using 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide (ASP(+)) as a fluorescent substrate. Initial ASP(+) uptake was inhibited by a cationic uremic metabolites mixture and by the histamine H2-receptor antagonist, cimetidine. In conclusion, a 'living membrane' of renal epithelial cells on MicroPES HFM with demonstrated active organic cation transport was successfully established as a first step in BAK engineering.

  12. Human proximal tubule epithelial cells cultured on hollow fibers: living membranes that actively transport organic cations

    PubMed Central

    Jansen, J.; De Napoli, I. E; Fedecostante, M.; Schophuizen, C. M. S.; Chevtchik, N. V.; Wilmer, M. J.; van Asbeck, A. H.; Croes, H. J.; Pertijs, J. C.; Wetzels, J. F. M.; Hilbrands, L. B.; van den Heuvel, L. P.; Hoenderop, J. G.; Stamatialis, D.; Masereeuw, R.

    2015-01-01

    The bioartificial kidney (BAK) aims at improving dialysis by developing ‘living membranes’ for cells-aided removal of uremic metabolites. Here, unique human conditionally immortalized proximal tubule epithelial cell (ciPTEC) monolayers were cultured on biofunctionalized MicroPES (polyethersulfone) hollow fiber membranes (HFM) and functionally tested using microfluidics. Tight monolayer formation was demonstrated by abundant zonula occludens-1 (ZO-1) protein expression along the tight junctions of matured ciPTEC on HFM. A clear barrier function of the monolayer was confirmed by limited diffusion of FITC-inulin. The activity of the organic cation transporter 2 (OCT2) in ciPTEC was evaluated in real-time using a perfusion system by confocal microscopy using 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide (ASP+) as a fluorescent substrate. Initial ASP+ uptake was inhibited by a cationic uremic metabolites mixture and by the histamine H2-receptor antagonist, cimetidine. In conclusion, a ‘living membrane’ of renal epithelial cells on MicroPES HFM with demonstrated active organic cation transport was successfully established as a first step in BAK engineering. PMID:26567716

  13. Functions of Cholesterol and the Cholesterol Bilayer Domain Specific to the Fiber-Cell Plasma Membrane of the Eye Lens

    PubMed Central

    Subczynski, Witold K.; Raguz, Marija; Widomska, Justyna; Mainali, Laxman; Konovalov, Alexey

    2012-01-01

    The most unique feature of the eye lens fiber-cell plasma membrane is its extremely high cholesterol content. Cholesterol saturates the bulk phospholipid bilayer and induces formation of immiscible cholesterol bilayer domains (CBDs) within the membrane. Our results (based on EPR spin-labeling experiments with lens-lipid membranes), along with a literature search, have allowed us to identify the significant functions of cholesterol specific to the fiber-cell plasma membrane, which are manifest through cholesterol-membrane interactions. The crucial role is played by the CBD. The presence of the CBD ensures that the surrounding phospholipid bilayer is saturated with cholesterol. The saturating cholesterol content in fiber-cell membranes keeps the bulk physical properties of lens-lipid membranes consistent and independent of changes in phospholipid composition. Thus, the CBD helps to maintain lens-membrane homeostasis when the membrane phospholipid composition changes significantly. The CBD raises the barrier for oxygen transport across the fiber-cell membrane, which should help to maintain a low oxygen concentration in the lens interior. It is hypothesized that the appearance of the CBD in the fiber-cell membrane is controlled by the phospholipid composition of the membrane. Saturation with cholesterol smoothes the phospholipid-bilayer surface, which should decrease light scattering and help to maintain lens transparency. Other functions of cholesterol include formation of hydrophobic and rigidity barriers across the bulk phospholipid-cholesterol domain and formation of hydrophobic channels in the central region of the membrane for transport of small, nonpolar molecules parallel to the membrane surface. In this review, we will provide data supporting these hypotheses. PMID:22207480

  14. The Effects of Elastic Fiber Protein Insufficiency and Treatment on the Modulus of Arterial Smooth Muscle Cells

    PubMed Central

    Gabriela Espinosa, M.; Gardner, William S.; Bennett, Lisa; Sather, Bradley A.; Yanagisawa, Hiromi; Wagenseil, Jessica E.

    2014-01-01

    Elastic fibers are critical for the mechanical function of the large arteries. Mechanical effects of elastic fiber protein deficiency have been investigated in whole arteries, but not in isolated smooth muscle cells (SMCs). The elastic moduli of SMCs from elastin (Eln-/-) and fibulin-4 (Fbln4-/-) knockout mice were measured using atomic force microscopy. Compared to control SMCs, the modulus of Eln-/- SMCs is reduced by 40%, but is unchanged in Fbln4-/- SMCs. The Eln-/- SMC modulus is rescued by soluble or α elastin treatment. Altered gene expression, specifically of calponin, suggests that SMC phenotypic modulation may be responsible for the modulus changes. PMID:24322348

  15. Asbestos fibers and interleukin-1 upregulate the formation of reactive nitrogen species in rat pleural mesothelial cells.

    PubMed

    Choe, N; Tanaka, S; Kagan, E

    1998-08-01

    Nitric oxide radical (.NO) and peroxynitrite anion (ONOO-) have been implicated in lung inflammation and may be important in pleural injury. The present study was undertaken to determine the effects of asbestos exposure and cytokine stimulation on .NO and ONOO- production by rat pleural mesothelial cells. Accordingly, rat parietal pleural mesothelial cells were cultured for 2 to 72 h with or without 50 ng/ml of recombinant interleukin-1beta (IL-1beta) in the presence (1.05 to 8.4 microg/cm2) or absence of crocidolite or chrysotile asbestos fibers. The effects of asbestos were compared with those of carbonyl iron, a nonfibrogenic particulate. Mesothelial cell messenger RNA (mRNA) expression of the inducible form of .NO synthase (iNOS), assessed with the reverse transcription-polymerase chain reaction (RT-PCR), increased progressively from 2 to 12 h in IL-1beta-containing cultures. Nitrite (NO2-), the stable oxidation product of .NO in mesothelial cell conditioned medium, was assayed through the Griess reaction. Both types of asbestos fibers (chrysotile > crocidolite) upregulated the formation of NO2- in mesothelial cells costimulated with IL-1beta in a concentration-dependent and time-dependent fashion. In contrast, carbonyl iron did not upregulate NO2- formation in IL-1beta-stimulated cells. Both types of asbestos fibers also induced iNOS protein expression and the formation of nitrotyrosine in mesothelial cells and greatly induced the formation of nitrate (NO3-), a surrogate marker of ONOO- formation, in IL-1beta-stimulated cells. However, the effects of chrysotile were notably greater than those of crocidolite. These findings may have significance for the induction of pleural injury by asbestos fibers.

  16. The use of fiber-reinforced scaffolds cocultured with Schwann cells and vascular endothelial cells to repair rabbit sciatic nerve defect with vascularization.

    PubMed

    Gao, Hongyang; You, Yang; Zhang, Guoping; Zhao, Feng; Sha, Ziyi; Shen, Yong

    2013-01-01

    To explore the feasibility of biodegradable fiber-reinforced 3D scaffolds with satisfactory mechanical properties for the repair of long-distance sciatic nerve defect in rabbits and effects of vascularized graft in early stage on the recovery of neurological function, Schwann cells and vascular endothelial cells were cocultured in the fiber-reinforced 3D scaffolds. Experiment group which used prevascularized nerve complex for the repair of sciatic nerve defect and control group which only cultured with Schwann cells were set. The animals in both groups underwent electromyography to show the status of the neurological function recovery at 4, 8, and 16 weeks after the surgery. Sciatic nerve regeneration and myelination were observed under the light microscope and electron microscope. Myelin sheath thickness, axonal diameter, and number of myelinated nerve fiber were quantitatively analyzed using image analysis system. The recovery of foot ulcer, the velocity of nerve conduction, the number of regenerating nerve fiber, and the recovery of ultrastructure were increased in the experimental group than those in the control group. Prevascularized tissue engineered fiber-reinforced 3D scaffolds for the repair of sciatic nerve defects in rabbits can effectively promote the recovery of neurological function.

  17. Design of fibers spun from carbon nanotube-sphere binary colloidal systems as substrates for cell behaviour control

    NASA Astrophysics Data System (ADS)

    Polizu, Stefania

    spinnability of the mixture for the fabrication of macroscopic threads. Moreover, by spinning from a binary colloidal system, we generate new conditions for the coagulation mechanism. By initiating the suspension of PLGA nanoparticles, we tailor the characteristics of new fibers, particularly their biodegradability and their biocompatibility. Thanks to PLGA, the fibers become partially biodegradable, which is an important achievement, considering that biodegradabilty in physiological conditions is a limitation for CNTs and PVA. The degradation process gives rise to a fibrillar structure in which CNTs form a framework-like arrangement that overwhelms the releasing effects of nanotubes, a critical point for long term biocompatibility. The permanence of nanotubes in a structured network increases the contact with cells and maintains their biofunctionality during and after the biodegradation of macroscopic fiber. We propose a hybrid approach to produce CNT-fibers as neural biomaterial. The characteristics of these fibers, as determined through this work, demonstrate the validity of this method for the design of new fibrillar substrates for cell sustaining the growth of cells. Moreover, the presence of an aqueous coagulant medium results in the material's cleanness and allows the introduction of numerous active agents or biological molecules without their denaturation. This is an opportunity for the application of pre- or post-treatments in order to manufacture complex hybrid biomaterials containing CNTs. The future of these fibers looks promising. They are the first fibers produced by a hybrid approach using the wet spinning process. They are in vitro biocompatible and biodegradable. (Abstract shortened by UMI.)

  18. Osteogenesis of human adipose-derived stem cells on poly(dopamine)-coated electrospun poly(lactic acid) fiber mats.

    PubMed

    Lin, Chi-Chang; Fu, Shu-Juan

    2016-01-01

    Electrospinning is a versatile technique to generate large quantities of micro- or nano-fibers from a wide variety of shapes and sizes of polymer. The aim of this study is to develop functionalized electrospun nano-fibers and use a mussel-inspired surface coating to regulate adhesion, proliferation and differentiation of human adipose-derived stem cells (hADSCs). We prepared poly(lactic acid) (PLA) fibers coated with polydopamine (PDA). The morphology, chemical composition, and surface properties of PDA/PLA were characterized by SEM and XPS. PDA/PLA modulated hADSCs' responses in several ways. Firstly, adhesion and proliferation of hADSCs cultured on PDA/PLA were significantly enhanced relative to those on PLA. Increased focal adhesion kinase (FAK) and collagen I levels and enhanced cell attachment and cell cycle progression were observed upon an increase in PDA content. In addition, the ALP activity and osteocalcin of hADSCs cultured on PDA/PLA were significantly higher than seen in those cultured on a pure PLA mat. Moreover, hADSCs cultured on PDA/PLA showed up-regulation of the ang-1 and vWF proteins associated with angiogenesis differentiation. Our results demonstrate that the bio-inspired coating synthetic degradable PLA polymer can be used as a simple technique to render the surfaces of synthetic biodegradable fibers, thus enabling them to direct the specific responses of hADSCs.

  19. Catalytic Improvement on Counter Electrode of Dye-Sensitized Solar Cells Using Electrospun Pt Nano-Fibers.

    PubMed

    Seol, Hyunwoong; Shiratani, Masaharu; Seneekatima, Kannanut; Pornprasertsuk, Rojana

    2016-04-01

    A dye-sensitized solar cell is one of cost-competitive photovoltaic devices. For higher performance, all components have been actively studied and improved. However, Pt is still a dominant catalyst since first development although some catalytic materials were studied so far. Catalytic materials of counter electrode play an important role in the performance because it supplies electrons from counter electrode to electrolyte. Therefore, the catalytic activation of counter electrode is closely connected with the performance enhancement. In this work, Pt nano-fiber was fabricated by electrospinning and applied for the counter electrode. Its wide surface area is advantageous for good conductivity and catalytic activation. Morphological characteristics of nano-fibers were analyzed according to electrospinning conditions. Photovoltaic properties, cyclic voltammetry, impedance analysis verified the catalytic activation. Consequently, dye-sensitized solar cell with Pt nano-fiber electrospun at 5.0 kV of applied voltage had higher performance than conventional dye-sensitized solar cell with Pt thin film. This work is significant for related researches because all nano-fibers counter electrode material proposed so far never exceeded the performance of conventional Pt counter electrode.

  20. Three-dimensional matrix fiber alignment modulates cell migration and MT1-MMP utility by spatially and temporally directing protrusions.

    PubMed

    Fraley, Stephanie I; Wu, Pei-Hsun; He, Lijuan; Feng, Yunfeng; Krisnamurthy, Ranjini; Longmore, Gregory D; Wirtz, Denis

    2015-10-01

    Multiple attributes of the three-dimensional (3D) extracellular matrix (ECM) have been independently implicated as regulators of cell motility, including pore size, crosslink density, structural organization, and stiffness. However, these parameters cannot be independently varied within a complex 3D ECM protein network. We present an integrated, quantitative study of these parameters across a broad range of complex matrix configurations using self-assembling 3D collagen and show how each parameter relates to the others and to cell motility. Increasing collagen density resulted in a decrease and then an increase in both pore size and fiber alignment, which both correlated significantly with cell motility but not bulk matrix stiffness within the range tested. However, using the crosslinking enzyme Transglutaminase II to alter microstructure independently of density revealed that motility is most significantly predicted by fiber alignment. Cellular protrusion rate, protrusion orientation, speed of migration, and invasion distance showed coupled biphasic responses to increasing collagen density not predicted by 2D models or by stiffness, but instead by fiber alignment. The requirement of matrix metalloproteinase (MMP) activity was also observed to depend on microstructure, and a threshold of MMP utility was identified. Our results suggest that fiber topography guides protrusions and thereby MMP activity and motility.

  1. Actin stress fiber disruption and tropomysin isoform switching in normal thyroid epithelial cells stimulated by thyrotropin and phorbol esters

    SciTech Connect

    Roger, P.P.; Rickaert, F.; Lamy, F.; Authelet, M.; Dumont, J.E. )

    1989-05-01

    Thyrotropin (TSH), through cyclic AMP, promotes both proliferation and differentiation expression in dog thyroid epithelial cells in primary culture, whereas the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) also stimulates proliferation but antagonizes differentiating effects of TSH. In this study, within 20 min both factors triggered the disruption of actin-containing stress fibers. This process preceded distinct morphological changes: cytoplasmic retraction and arborization in response to TSH and cyclic AMP, cell shape distortion, and increased motility in response to TPA and diacylglycerol. TSH and TPA also induced a marked decrease in the synthesis of three high M{sub r} tropomyosin isoforms, which were not present in dog thyroid tissue but appeared in culture during cell spreading and stress fiber formation. The tropomyosin isoform switching observed here closely resembled similar processes in various cells transformed by oncogenic viruses. However, it did not correlate with differentiation or mitogenic activation. Contrasting with current hypothesis on this process in transformed cells, tropomyosin isoform switching in normal thyroid cells was preceded and thus might be caused by early disruption of stress fibers.

  2. Enhanced electron collection efficiency in dye-sensitized solar cells based on nanostructured TiO(2) hollow fibers.

    PubMed

    Ghadiri, Elham; Taghavinia, Nima; Zakeeruddin, Shaik M; Grätzel, Michael; Moser, Jacques-E

    2010-05-12

    Nanostructured TiO(2) hollow fibers have been prepared using natural cellulose fibers as a template. This cheap and easily processed material was used to produce highly porous photoanodes incorporated in dye-sensitized solar cells and exhibited remarkably enhanced electron transport properties compared to mesoscopic films made of spherical nanoparticles. Photoinjected electron lifetime, in particular, was multiplied by 3-4 in the fiber morphology, while the electron transport rate within the fibrous photoanaode was doubled. A nearly quantitative absorbed photon-to-electrical current conversion yield exceeding 95% was achieved upon excitation at 550 nm and a photovoltaic power conversion efficiency of 7.2% reached under simulated AM 1.5 (100 mW cm(-2)) solar illumination.

  3. GeO2-SiO2-chitosan-medium-coated hollow optical fiber for cell immobilization.

    PubMed

    Zhong, Nian-Bing; Zhu, Xun; Liao, Qiang; Wang, Yong-Zhong; Chen, Rong

    2013-08-15

    A GeO(2)-SiO(2)-chitosan-medium (GSCM)-coated hollow optical fiber (HOF) is proposed. The HOF consists of three parts: the fiber core (air), cladding (SiO(2)), and coating (GSCM), which shows the highest refractive index of the three. The HOF's luminescence properties and surface morphology are investigated. Their adsorption capacity for Rhodopseudomonas palustris CQK 01 is also assayed. We discovered that when the amount of 2GeO(2)-SiO(2) sol dopant is 0.9 mass percent, the HOF exhibits the highest luminous intensity and uniform light distribution, and the adsorption capacity for the cell is 3.2 times higher than that of a normal solid optical fiber.

  4. Improving the performance of microbial fuel cells by reducing the inherent resistivity of carbon fiber brush anodes

    NASA Astrophysics Data System (ADS)

    Xie, Yang'en; Ma, Zhaokun; Song, Huaihe; Wang, Huiyao; Xu, Pei

    2017-04-01

    This study investigated the effect of carbon fibers as brush anode materials on the performance of microbial fuel cells (MFCs). Two types of carbon fibers with different electrical resistivity and functionality - polyacrylonitrile (PAN) (ρ: 28.0 μΩ m) and pitch (ρ: 2.05 μΩ m) were investigated. X-ray photoelectron spectroscopy analysis showed that the PAN- and pitch-based carbon fibers presented almost the same surface elements and functional groups, and there was no significant difference in microbial growth on the brush anodes. Current interrupt and steady discharging methods demonstrated the pitch-based carbon brush anodes had lower ohmic resistance and generated higher power density. After nitric acid treatment, the power density generated by the PAN- and pitch-based anodes increased by 29.3% and 26.7%, achieving 816 and 895 mW m-2, respectively. Using pitch-based carbon fiber brush as anode attained better performance than the widely used PAN-based carbon brush. The acid treated pitch-based carbon fibers provide a promising alternative to highly efficient anode materials for the extensive application of MFCs.

  5. Role of mast cells in wound healing process after glass - fiber composite implant in rats

    PubMed Central

    Rodella, L F; Rezzani, Rita; Buffoli, Barbara; Bonomini, Francesca; Tengattini, Sandra; Laffranchi, Laura; Paganelli, C; Sapelli, P L; Bianchi, Rossella

    2006-01-01

    Glass-fiber composites are frequently used in dentistry. In order to evaluate their biocompatibility we tested, in an experimental model “in vivo”, their tissue response pointing our attention on presence of mast cells (MCs) and fibrotic process. Sprague Dawley rats were used for the experimental design. The fibers were introduced in a subcutaneous pocket along the middle dorsal line between the two scapulas for 7, 14 or 21 days. At the end of the treatments the skins were excised and then processed for Toluidine Blue, to determine the presence of MCs, and Picrosirius Red staining, to evaluate the presence of fibrotic tissue. Our preliminary results showed and increase of both MC number and deposition of collagen type I, which characterized the fibrotic tissue. So, subsequent aims of our study were to evaluate the role played by MCs in tissue fibrosis and to give a possible explanation regarding the mechanisms that were responsible of biological response observed, through the analyses of some proteins, such as metalloproteinase-2 (MMP-2), its inhibitor (TIMP-2) and transforming growth factor-β (TGF-β). Our data confirmed the involvement of TGF-β, released by MCs, in the disruption of the equilibrium between MMP-2 and TIMP-2 that were implicated in the enhancement of fibrosis. In summary, this study demonstrate that this type of materials induced an inflammatory response at the site of implant and help to clarify what type of mechanism and which proteins are involved in this biological response. Nevertheless, more extensive investigations are in progress to better evaluate the inflammatory process. PMID:17125597

  6. Structure of a pentameric virion-associated fiber with a potential role in Orsay virus entry to host cells

    PubMed Central

    Yuan, Wang; Zhou, Ying; Wang, Tao; Demeler, Borries; Zhong, Weiwei; Tao, Yizhi J.

    2017-01-01

    Despite the wide use of Caenorhabditis elegans as a model organism, the first virus naturally infecting this organism was not discovered until six years ago. The Orsay virus and its related nematode viruses have a positive-sense RNA genome, encoding three proteins: CP, RdRP, and a novel δ protein that shares no homology with any other proteins. δ can be expressed either as a free δ or a CP-δ fusion protein by ribosomal frameshift, but the structure and function of both δ and CP-δ remain unknown. Using a combination of electron microscopy, X-ray crystallography, computational and biophysical analyses, here we show that the Orsay δ protein forms a ~420-Å long, pentameric fiber with an N-terminal α-helical bundle, a β-stranded filament in the middle, and a C-terminal head domain. The pentameric nature of the δ fiber has been independently confirmed by both mass spectrometry and analytical ultracentrifugation. Recombinant Orsay capsid containing CP-δ shows protruding long fibers with globular heads at the distal end. Mutant viruses with disrupted CP-δ fibers were generated by organism-based reverse genetics. These viruses were found to be either non-viable or with poor infectivity according to phenotypic and qRT-PCR analyses. Furthermore, addition of purified δ proteins to worm culture greatly reduced Orsay infectivity in a sequence-specific manner. Based on the structure resemblance between the Orsay CP-δ fiber and the fibers from reovirus and adenovirus, we propose that CP-δ functions as a cell attachment protein to mediate Orsay entry into worm intestine cells. PMID:28241071

  7. The Dual Functions of WLIM1a in Cell Elongation and Secondary Wall Formation in Developing Cotton Fibers[C][W

    PubMed Central

    Han, Li-Bo; Li, Yuan-Bao; Wang, Hai-Yun; Wu, Xiao-Min; Li, Chun-Li; Luo, Ming; Wu, Shen-Jie; Kong, Zhao-Sheng; Pei, Yan; Jiao, Gai-Li; Xia, Gui-Xian

    2013-01-01

    LIN-11, Isl1 and MEC-3 (LIM)-domain proteins play pivotal roles in a variety of cellular processes in animals, but plant LIM functions remain largely unexplored. Here, we demonstrate dual roles of the WLIM1a gene in fiber development in upland cotton (Gossypium hirsutum). WLIM1a is preferentially expressed during the elongation and secondary wall synthesis stages in developing fibers. Overexpression of WLIM1a in cotton led to significant changes in fiber length and secondary wall structure. Compared with the wild type, fibers of WLIM1a-overexpressing plants grew longer and formed a thinner and more compact secondary cell wall, which contributed to improved fiber strength and fineness. Functional studies demonstrated that (1) WLIM1a acts as an actin bundler to facilitate elongation of fiber cells and (2) WLIM1a also functions as a transcription factor to activate expression of Phe ammonia lyase–box genes involved in phenylpropanoid biosynthesis to build up the secondary cell wall. WLIM1a localizes in the cytosol and nucleus and moves into the nucleus in response to hydrogen peroxide. Taken together, these results demonstrate that WLIM1a has dual roles in cotton fiber development, elongation, and secondary wall formation. Moreover, our study shows that lignin/lignin-like phenolics may substantially affect cotton fiber quality; this finding may guide cotton breeding for improved fiber traits. PMID:24220634

  8. Charge-discharge characteristics of mesophase-pitch-based carbon fibers for lithium cells

    SciTech Connect

    Imanishi, N.; Kashiwagi, H.; Ichikawa, T.; Takeda, Y.; Yamamoto, O. ); Inagaki, M. )

    1993-02-01

    Mesophase-pitch-based carbon fibers were heat-treated at high temperatures (2,600 or 2,800 C) and examined as anodes for lithium secondary batteries. Four types of carbon fibers were used whose cross-sectional views are: a radial texture with wedge (type A), a radial texture with fine zigzag layers (type B), a double texture (type C), and a concentric texture (type D). Lithium could not be deintercalated after the first lithium intercalation in the type A carbon fiber. The structure of the type A fiber was destroyed during lithium intercalation. The other three types of carbon fibers showed good rechargeability on the first cycle, but demonstrated different behavior after 30 cycles. The highest lithium intercalation and deintercalation capacity was observed for the radially oriented carbon fiber (type B). The x-ray results showed a reversible change in the lattice along the c-axis during the intercalation and deintercalation cycle.

  9. Follicular dermal papilla structures by organization of epithelial and mesenchymal cells in interfacial polyelectrolyte complex fibers.

    PubMed

    Lim, Tze Chiun; Leong, Meng Fatt; Lu, Hongfang; Du, Chan; Gao, Shujun; Wan, Andrew C A; Ying, Jackie Y

    2013-09-01

    The hair follicle is a regenerating organ that produces a new hair shaft during each growth cycle. Development and cycling of the hair follicle is governed by interactions between the epithelial and mesenchymal components. Therefore, development of an engineered 3D hair follicle would be useful for studying these interactions to identify strategies for treatment of hair loss. We have developed a technique suitable for assembly of different cell types in close proximity in fibrous hydrogel scaffolds with resolutions of ∼50 μm. By assembly of dermal papilla (DP) and keratinocytes, structures similar to the native hair bulb arrangement are formed. Gene expression of these constructs showed up-regulation of molecules involved in epithelial-mesenchymal interactions of the hair follicle. Implantation of the follicular structures in SCID mice led to the formation of hair follicle-like structures, thus demonstrating their hair inductive ability. The transparency of the fiber matrix and the small dimensions of the follicular structures allowed the direct quantitation of DP cell proliferation by confocal microscopy, clearly illustrating the promoting or inhibitory effects of hair growth regulating agents. Collectively, our results suggested a promising application of these 3D engineered follicular structures for in vitro screening and testing of drugs for hair growth therapy.

  10. Regional correlation among ganglion cell complex, nerve fiber layer, and visual field loss in glaucoma.

    PubMed

    Le, Phuc V; Tan, Ou; Chopra, Vikas; Francis, Brian A; Ragab, Omar; Varma, Rohit; Huang, David

    2013-06-21

    To analyze the relationship among macular ganglion cell complex (GCC) thickness, peripapillary nerve fiber layer (NFL) thickness, and visual field (VF) defects in patients with glaucoma. A Fourier-domain optical coherence tomography (FD-OCT) system was used to map the macula and peripapillary regions of the retina in 56 eyes of 38 patients with perimetric glaucoma. The macular GCC and peripapillary NFL thicknesses were mapped and standard automated perimetry (SAP) was performed. Loss of GCC and NFL were correlated with the VF map on both a point-by-point and regional basis. Correlation between GCC thickness and peripapillary NFL thickness produced a detailed correspondence map that demonstrates the arcuate course of the NFL in the macula. Corresponding regions within the GCC, NFL, and VF maps demonstrate significant correlation, once parafoveal retinal ganglion cell (RGC) displacement is taken into account. There are significant point-specific and regional correlations between GCC loss, NFL loss, and deficits on SAP. Using these different data sources together may improve our understanding of glaucomatous damage and aid in the management of patients with glaucoma.

  11. Regional Correlation Among Ganglion Cell Complex, Nerve Fiber Layer, and Visual Field Loss in Glaucoma

    PubMed Central

    Le, Phuc V.; Tan, Ou; Chopra, Vikas; Francis, Brian A.; Ragab, Omar; Varma, Rohit; Huang, David

    2013-01-01

    Purpose. To analyze the relationship among macular ganglion cell complex (GCC) thickness, peripapillary nerve fiber layer (NFL) thickness, and visual field (VF) defects in patients with glaucoma. Methods. A Fourier-domain optical coherence tomography (FD-OCT) system was used to map the macula and peripapillary regions of the retina in 56 eyes of 38 patients with perimetric glaucoma. The macular GCC and peripapillary NFL thicknesses were mapped and standard automated perimetry (SAP) was performed. Loss of GCC and NFL were correlated with the VF map on both a point-by-point and regional basis. Results. Correlation between GCC thickness and peripapillary NFL thickness produced a detailed correspondence map that demonstrates the arcuate course of the NFL in the macula. Corresponding regions within the GCC, NFL, and VF maps demonstrate significant correlation, once parafoveal retinal ganglion cell (RGC) displacement is taken into account. Conclusions. There are significant point-specific and regional correlations between GCC loss, NFL loss, and deficits on SAP. Using these different data sources together may improve our understanding of glaucomatous damage and aid in the management of patients with glaucoma. PMID:23716631

  12. Beyond “all-or-nothing” climbing fibers: graded representation of teaching signals in Purkinje cells

    PubMed Central

    Najafi, Farzaneh; Medina, Javier F.

    2013-01-01

    Arguments about the function of the climbing fiber (CF) input to the cerebellar cortex have fueled a rabid debate that started over 40 years ago, and continues to polarize the field to this day. The origin of the controversy can be traced back to 1969, the year David Marr published part of his dissertation work in a paper entitled “A theory of cerebellar cortex.” In Marr’s theory, CFs play a key role during the process of motor learning, providing an instructive signal that serves as a “teacher” for the post-synaptic Purkinje cells. Although this influential idea has found its way into the mainstream, a number of objections have been raised. For example, several investigators have pointed out that the seemingly “all-or-nothing” activation of the CF input provides little information and is too ambiguous to serve as an effective instructive signal. Here, we take a fresh look at these arguments in light of new evidence about the peculiar physiology of CFs. Based on recent findings we propose that at the level of an individual Purkinje cell, a graded instructive signal can be effectively encoded via pre- or post-synaptic modulation of its one and only CF input. PMID:23847473

  13. Adsorption of albumin on flax fibers increases endothelial cell adhesion and blood compatibility in vitro.

    PubMed

    Michel, Sophie A A X; Knetsch, Menno L W; Koole, Leo H

    2014-01-01

    The physical and chemical properties of flax (linen) are attractive from the perspective of biomaterials science and engineering. Flax textiles uniquely combine hydrophilicity and strength, with the technical know-how to produce precisely engineered two- and three-dimensional knitted or woven structures. It is, however, extremely difficult to completely remove endotoxins from the flax, and this essentially precludes the use of linen for implant purposes. Herein, the potential utility of flax textiles for blood-contacting applications is investigated, using purified two-dimensional mesh specimens, with and without an albumin surface coating. It was hypothesized that the albumin coating will abolish the effect of adherent endotoxins at the flax's surface. In vitro cell viability assays showed that the flax mesh ± albumin is not cytotoxic. The albumin coating reduced (but not abolished) the effect of surface-exposed endotoxins (Limulus amebocyte lysate test). Under dynamic conditions, the albumin coating favors coverage with endothelial cells. Experiments with fresh human blood plasma (platelet-rich and platelet-free) showed that the albumin coating reduces the thrombogenicity in vitro. Platelets adhered to the albumin-coated flax mesh showed a less flattened structure. Although the results of this work cannot be extrapolated easily to in vivo situations, the data reveal that woven or knitted tubular structures produced from flax fibers may hold promise as implantable blood contacting devices like for instance vascular grafts.

  14. Effect of nickel impregnated hollow fiber anode for micro tubular solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    He, Beibei; Ling, Yihan; Xu, Jianmei; Zhao, Ling; Cheng, Jigui

    2014-07-01

    A micro tubular solid oxide fuel cells (MT-SOFCs) with a cell configuration of Ni impregnated Ni-Gd0.1Ce0.9O1.95 (GDC)/GDC/La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF)-GDC has been prepared by the phase inversion and impregnation technique. A special asymmetrical structure consisting of a sponge-like layer and a finger-like porous layer for hollow fiber anode is obtained by the phase inversion. Fine Ni specie particles are then coated on the surface of anode using impregnation method. The enhancement in electronic conductivity of anode by Ni modification is beneficial to current collection of MT-SOFCs. Meanwhile, the catalytic activity of anode is also improved due to the introduction of Ni nano-particles. Thus, the Ni modified MT-SOFCs exhibit high power densities, such as 0.69 W cm-2 at 600 °C. The encouraging results demonstrate that the Ni impregnation is an effective way to improve anode microstructure of MT-SOFCs.

  15. [Research on fiber methane sensing system based on prism gas cell].

    PubMed

    Wu, Xi-Jun; Wang, Yu-Tian; Liu, Xue-Cai; Li, Shu-Jun

    2010-05-01

    A novel fiber methane detection system was constructed based on integration of prism gas cell and harmonic detection technique. The system can be applied to broad-range concentration detection. Grounded on the Beer-Lambert approximation, the detection of various concentration (0-20%) of methane was completed using subtraction of background and ratio processing method, as the atmosphere surroundings was treated as background. The direct absorption spectra for various concentration were measured using GRIN gas cell, combined with available DFB-LD, and the R5 line of the 2v3 band of methane was selected as absorption peak. The system was tested online during gas mixing process and the linear relation between system indication and concentration variation was validated, while the stability and dynamic response characteristics was confirmed by experiments. The system sensitivity can be adjusted according to the concentration level of various field environments by changing the prism distance using step motor. So that, the system can be applied to various application fields and can be adopted as a monitoring instrument for coalmine tunnel and natural gas pipeline.

  16. Flow perfusion enhances the calcified matrix deposition of marrow stromal cells in biodegradable nonwoven fiber mesh scaffolds.

    PubMed

    Sikavitsas, Vassilios I; Bancroft, Gregory N; Lemoine, Jeremy J; Liebschner, Michael A K; Dauner, Martin; Mikos, Antonios G

    2005-01-01

    In this study, we report on the ability of resorbable poly(L-lactic acid) (PLLA) nonwoven scaffolds to support the attachment, growth, and differentiation of marrow stromal cells (MSCs) under fluid flow. Rat MSCs were isolated from young male Wistar rats and expanded using established methods. The cells were then seeded on PLLA nonwoven fiber meshes. The PLLA nonwoven fiber meshes had 99% porosity, 17 microm fiber diameter, 10 mm scaffold diameter, and 1.7-mm thickness. The nonwoven PLLA meshes were seeded with a cell suspension of 5 x 10(5) cells in 300 microl, and cultured in a flow perfusion bioreactor and under static conditions. Cell/polymer nonwoven scaffolds cultured under flow perfusion had significantly higher amounts of calcified matrix deposited on them after 16 days of culture. Microcomputed tomography revealed that the in vitro generated extracellular matrix in the scaffolds cultured under static conditions was denser at the periphery of the scaffold while in the scaffolds cultured in the perfusion bioreactor the extracellular matrix demonstrated a more homogeneous distribution. These results show that flow perfusion accelerates the proliferation and differentiation of MSCs, seeded on nonwoven PLLA scaffolds, toward the osteoblastic phenotype, and improves the distribution of the in vitro generated calcified extracellular matrix.

  17. Efficient single muscle fiber isolation from alcohol-fixed adult muscle following β-galactosidase staining for satellite cell detection.

    PubMed

    Verma, Mayank; Asakura, Atsushi

    2011-01-01

    Staining for β-galactosidase activity for whole tissues, sections, and cells is a common method to detect expression of β-galactosidase reporter transgene as well as senescence-dependent β-galactosidase activity. Choice of fixatives is a critical step for detection of β-galactosidase activity, subsequent immunostaining, and enzymatic digestion of tissue to dissociate cells. In this report, the authors examined several aldehyde and alcohol fixatives in mouse skeletal muscle tissues for their efficiency at improving detection of β-galactosidase activity as well as detection by immunostaining. In addition, fixatives were also analyzed for their efficiency for collagenase digestion to isolate single muscle fibers on postfixed β-galactosidase-stained whole skeletal muscle tissues. The results show that fixing cells with isopropanol yields the greatest reliability and intensity in both β-galactosidase staining as well as double staining for β-galactosidase activity and antibodies. In addition, isopropanol and ethanol, but not glutaraldehyde or paraformaldehyde, allow for the isolation of single muscle fibers from the diaphragm and tibialis anterior muscles following postfixed β-galactosidase staining. Using this method, it is possible to identify the amount of cells that occupy the satellite cell compartment in single muscle fibers prepared from any muscle tissues, including tibialis anterior muscle and diaphragm.

  18. Salinomycin inhibits growth of pancreatic cancer and cancer cell migration by disruption of actin stress fiber integrity.

    PubMed

    Schenk, Miriam; Aykut, Berk; Teske, Christian; Giese, Nathalia A; Weitz, Juergen; Welsch, Thilo

    2015-03-28

    Pancreatic ductal adenocarcinoma (PDAC) is characterized by aggressive growth, early metastasis and high resistance to chemotherapy. Salinomycin is a promising compound eliminating cancer stem cells and retarding cancer cell migration. The present study investigated the effectiveness of salinomycin against PDAC in vivo and elucidated the mechanism of PDAC growth inhibition. Salinomycin treatment was well tolerated by the mice and significantly reduced tumor growth after 19 days compared to the control group (each n = 16). There was a trend that salinomycin also impeded metastatic spread to the liver and peritoneum. Whereas salinomycin moderately induced apoptosis and retarded proliferation at 5-10 µM, it strongly inhibited cancer cell migration that was accompanied by a marked loss of actin stress fibers after 6-9 h. Salinomycin silenced RhoA activity, and loss of stress fibers could be reversed by Rho activation. Moreover, salinomycin dislocated fascin from filopodia and stimulated Rac-associated circular dorsal ruffle formation. In conclusion, salinomycin is an effective and promising compound against PDAC. Besides its known stem cell-specific cytotoxic effects, salinomycin blocks cancer cell migration by disrupting stress fiber integrity and affecting the mutual Rho-GTPase balance. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  19. Induction of leukemia-specific CD8+ cytotoxic T cells with autologous myeloid leukemic cells maturated with a fiber-modified adenovirus encoding TNF-alpha.

    PubMed

    Saudemont, Aurore; Corm, Selim; Wickham, Thomas; Hetuin, Dominique; Quesnel, Bruno

    2005-06-01

    Acute myeloid leukemia (AML) cells can be differentiated into dendritic cells (DCs) using appropriate combinations of cytokines but generation of autologous antileukemic cytotoxic T cells using leukemic DCs remains difficult. Transduction by adenoviral vectors has been reported to induce efficient maturation of monocyte-derived DCs but AML cells are generally resistant to adenoviral gene transfer. In this study we tested the effects of adenoviral TNF-alpha gene transfer on maturation of AML cells using the fiber-modified AdTNF.F(pK7) adenovirus. All samples expressed high and sustained levels of TNF-alpha following transduction. AdTNF.F(pK7) induced significantly greater maturation of AML cells into antigen-presenting cells (APC) than did recombinant TNF-alpha or control adenoviral vector. Maturation of leukemic cells into APCs was mediated at least partially via a PI3K/mTOR pathway, as the inhibitors LY294002, wortmannin, and rapamycin inhibited the maturation effect induced by the AdTNF.F(pK7) adenovirus. In addition, CD8+ T cells expanded with AdTNF.F(pK7)-transduced AML cells showed greater expansion and specific CD8+ CTL activity against autologous AML cells than T cells expanded by other means. Thus, fiber-modified adenoviral vectors encoding TNF-alpha are able to maturate AML cells into APCs with high efficacy and reproducibility, providing a useful tool to generate efficiently specific CD8+ CTLs against leukemic disease.

  20. Gradation of mechanical properties in gas-diffusion electrode. Part 2: Heterogeneous carbon fiber and damage evolution in cell layers

    NASA Astrophysics Data System (ADS)

    Poornesh, K. K.; Cho, C. D.; Lee, G. B.; Tak, Y. S.

    In PEM fuel cell, gas-diffusion electrode (GDE) plays very significant role in force transmission from bipolar plate to the membrane. This paper investigates the effects of geometrical heterogeneities of gas-diffusion electrode layer (gas-diffusion layer (GDL) and catalyst layer (CL)) on mechanical damage evolution and propagation. We present a structural integrity principle of membrane electrode assembly (MEA) based on the interlayer stress transfer capacity and corresponding cell layer material response. Commonly observable damages such as rupture of hydrophobic coating and breakage of carbon fiber in gas-diffusion layer are attributed to the ductile to brittle phase transition within a single carbon fiber. Effect of material inhomogeneity on change in modulus, hardness, contact stiffness, and electrical contact resistance is also discussed. Fracture statistics of carbon fiber and variations in flexural strength of GDL are studied. The damage propagation in CL is perceived to be influenced by the type of gradation and the vicinity from which crack originates. Cohesive zone model has been proposed based on the traction-separation law to investigate the damage propagation throughout the two interfaces (carbon fiber/CL and CL/membrane).

  1. Reconstitution of the hippocampal mossy fiber and associational-commissural pathways in a novel dissociated cell culture system.

    PubMed Central

    Baranes, D; López-García, J C; Chen, M; Bailey, C H; Kandel, E R

    1996-01-01

    Synapses of the hippocampal mossy fiber pathway exhibit several characteristic features, including a unique form of long-term potentiation that does not require activation of the N-methyl-D-aspartate receptor by glutamate, a complex postsynaptic architecture, and sprouting in response to seizures. However, these connections have proven difficult to study in hippocampal slices because of their relative paucity (<0.4%) compared to commissural-collateral synapses. To overcome this problem, we have developed a novel dissociated cell culture system in which we have enriched mossy fiber synapses by increasing the ratio of granule-to-pyramidal cells. As in vivo, mossy fiber connections are composed of large dynorphin A-positive varicosities contacting complex spines (but without a restricted localization). The elementary synaptic connections are glutamatergic, inhibited by dynorphin A, and exhibit N-methyl-D-aspartate-independent long-term potentiation. Thus, the simplicity and experimental accessibility of this enriched in vitro mossy fiber pathway provides a new perspective for studying nonassociative plasticity in the mammalian central nervous system. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:8643467

  2. Metal-free polymer/MWCNT composite fiber as an efficient counter electrode in fiber shape dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Ali, Abid; Mujtaba Shah, Syed; Bozar, Sinem; Kazici, Mehmet; Keskin, Bahadır; Kaleli, Murat; Akyürekli, Salih; Günes, Serap

    2016-09-01

    Highly aligned multiwall carbon nanotubes (MWCNT) as fiber were modified with a conducting polymer via a simple dip coating method. Modified MWCNT exhibited admirable improvement in electrocatalytic activity for the reduction of tri-iodide in dye sensitized solar cells. Scanning electron microscopy images confirm the successful deposition of polymer on MWCNT. Cyclic voltammetry, square wave voltammetry and electrochemical impedance spectroscopy studies were carried out to investigate the inner mechanism for the charge transfer behaviour. Results from bare and modified electrodes revealed that the MWCNT/(poly (3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) composite electrode is much better at catalysing the {{{{I}}}3}-/{{{I}}}- redox couple compared to the pristine fiber electrode. The photoelectric conversion efficiency of 5.03% for the modified MWCNT electrodes was comparable with that of the conventional Pt-based electrode. The scientific results of this study reveal that MWCNT/PEDOT:PSS may be a better choice for the replacement of cost intensive electrode materials such as platinum. Good performance even after bending up to 90° and in-series connection to enhance the output voltage were also successfully achieved, highlighting the practical application of this novel device.

  3. A Raman cell based on hollow core photonic crystal fiber for human breath analysis

    SciTech Connect

    Chow, Kam Kong; Zeng, Haishan; Short, Michael; Lam, Stephen; McWilliams, Annette

    2014-09-15

    Purpose: Breath analysis has a potential prospect to benefit the medical field based on its perceived advantages to become a point-of-care, easy to use, and cost-effective technology. Early studies done by mass spectrometry show that volatile organic compounds from human breath can represent certain disease states of our bodies, such as lung cancer, and revealed the potential of breath analysis. But mass spectrometry is costly and has slow-turnaround time. The authors’ goal is to develop a more portable and cost effective device based on Raman spectroscopy and hollow core-photonic crystal fiber (HC-PCF) for breath analysis. Methods: Raman scattering is a photon-molecular interaction based on the kinetic modes of an analyte which offers unique fingerprint type signals that allow molecular identification. HC-PCF is a novel light guide which allows light to be confined in a hollow core and it can be filled with a gaseous sample. Raman signals generated by the gaseous sample (i.e., human breath) can be guided and collected effectively for spectral analysis. Results: A Raman-cell based on HC-PCF in the near infrared wavelength range was developed and tested in a single pass forward-scattering mode for different gaseous samples. Raman spectra were obtained successfully from reference gases (hydrogen, oxygen, carbon dioxide gases), ambient air, and a human breath sample. The calculated minimum detectable concentration of this system was ∼15 parts per million by volume, determined by measuring the carbon dioxide concentration in ambient air via the characteristic Raman peaks at 1286 and 1388 cm{sup −1}. Conclusions: The results of this study were compared to a previous study using HC-PCF to trap industrial gases and backward-scatter 514.5 nm light from them. The authors found that the method presented in this paper has an advantage to enhance the signal-to-noise ratio (SNR). This SNR advantage, coupled with the better transmission of HC-PCF in the near-IR than in the

  4. GluD2 Endows Parallel Fiber-Purkinje Cell Synapses with a High Regenerative Capacity.

    PubMed

    Ichikawa, Ryoichi; Sakimura, Kenji; Watanabe, Masahiko

    2016-04-27

    Although injured axons usually do not regenerate in the adult CNS, parallel fibers (PFs) regenerate synaptic connections onto cerebellar Purkinje cells (PCs). In this study, we investigated the role of GluD2 in this regenerative process after PF transection using GluD2-knock-out (KO) mice. All dendritic spines on distal dendrites were innervated by PFs in sham-operated wild-type controls, whereas one-third were devoid of innervation in GluD2-KO mice. In both genotypes, a steep drop in the number of PF synapses occurred with a reciprocal surge in the number of free spines on postlesion day 1, when the PF territory aberrantly expanded toward the proximal dendrites. In wild-type mice, the territory and number of PF synapses were nearly fully restored to normal on postlesion day 7, although PF density remained low. Moreover, presynaptic and postsynaptic elements were markedly enlarged, and the PF terminal-to-PC spine contact ratio increased from 1:1 to 1:2 at most synapses. On postlesion day 30, the size and contact ratio of PF synapses returned to sham-operated control values and PF density recovered through the sprouting and elongation of PF collaterals. However, GluD2-KO mice showed neither a hypertrophic response nor territorial restoration 7 d postlesion, nor the recovery of PF axons or synapses on postlesion day 30. This suggests that PF wiring regenerates initially by inducing hypertrophic responses in surviving synaptic elements (hypertrophic phase), followed by collateral formation by PF axons and retraction of PF synapses (remodeling phase). Without GluD2, no transition to these regenerative phases occurs. The glutamate receptor GluD2 expressed at parallel fiber (PF)-Purkinje cell (PC) synapses regulates the formation and maintenance of the synapses. To investigate the role of GluD2 in their extraordinarily high regenerative capacity, the process after surgical transection of PFs was compared between wild-type and GluD2-knock-out mice. We discovered that, in

  5. A Raman cell based on hollow core photonic crystal fiber for human breath analysis.

    PubMed

    Chow, Kam Kong; Short, Michael; Lam, Stephen; McWilliams, Annette; Zeng, Haishan

    2014-09-01

    Breath analysis has a potential prospect to benefit the medical field based on its perceived advantages to become a point-of-care, easy to use, and cost-effective technology. Early studies done by mass spectrometry show that volatile organic compounds from human breath can represent certain disease states of our bodies, such as lung cancer, and revealed the potential of breath analysis. But mass spectrometry is costly and has slow-turnaround time. The authors' goal is to develop a more portable and cost effective device based on Raman spectroscopy and hollow core-photonic crystal fiber (HC-PCF) for breath analysis. Raman scattering is a photon-molecular interaction based on the kinetic modes of an analyte which offers unique fingerprint type signals that allow molecular identification. HC-PCF is a novel light guide which allows light to be confined in a hollow core and it can be filled with a gaseous sample. Raman signals generated by the gaseous sample (i.e., human breath) can be guided and collected effectively for spectral analysis. A Raman-cell based on HC-PCF in the near infrared wavelength range was developed and tested in a single pass forward-scattering mode for different gaseous samples. Raman spectra were obtained successfully from reference gases (hydrogen, oxygen, carbon dioxide gases), ambient air, and a human breath sample. The calculated minimum detectable concentration of this system was ∼15 parts per million by volume, determined by measuring the carbon dioxide concentration in ambient air via the characteristic Raman peaks at 1286 and 1388 cm(-1). The results of this study were compared to a previous study using HC-PCF to trap industrial gases and backward-scatter 514.5 nm light from them. The authors found that the method presented in this paper has an advantage to enhance the signal-to-noise ratio (SNR). This SNR advantage, coupled with the better transmission of HC-PCF in the near-IR than in the visible wavelengths led to an estimated seven

  6. Circuit mechanisms of seizures in the pilocarpine model of chronic epilepsy: cell loss and mossy fiber sprouting.

    PubMed

    Mello, L E; Cavalheiro, E A; Tan, A M; Kupfer, W R; Pretorius, J K; Babb, T L; Finch, D M

    1993-01-01

    We used the pilocarpine model of chronic spontaneous recurrent seizures to evaluate the time course of supragranular dentate sprouting and to assess the relation between several changes that occur in epileptic tissue with different behavioral manifestations of this experimental model of temporal lobe epilepsy. Pilocarpine-induced status epilepticus (SE) invariably led to cell loss in the hilus of the dentate gyrus (DG) and to spontaneous recurrent seizures. Cell loss was often also noted in the DG and in hippocampal subfields CA1 and CA3. The seizures began to appear at a mean of 15 days after SE induction (silent period), recurred at variable frequencies for each animal, and lasted for as long as the animals were allowed to survive (325 days). The granule cell layer of the DG was dispersed in epileptic animals, and neo-Timm stains showed supra- and intragranular mossy fiber sprouting. Supragranular mossy fiber sprouting and dentate granule cell dispersion began to appear early after SE (as early as 4 and 9 days, respectively) and reached a plateau by 100 days. Animals with a greater degree of cell loss in hippocampal field CA3 showed later onset of chronic epilepsy (r = 0.83, p < 0.0005), suggesting that CA3 represents one of the routes for seizure spread. These results demonstrate that the pilocarpine model of chronic seizures replicates several of the features of human temporal lobe epilepsy (hippocampal cell loss, supra- and intragranular mossy fiber sprouting, dentate granule cell dispersion, spontaneous recurrent seizures) and that it may be a useful model for studying this human condition. The results also suggest that even though a certain amount of cell loss in specific areas may be essential for chronic seizures to occur, excessive cell loss may hinder epileptogenesis.

  7. Altered position of cell bodies and fibers in the ventromedial region in SF-1 knockout mice

    PubMed Central

    Büdefeld, Tomaz; Tobet, Stuart A.; Majdic, Gregor

    2011-01-01

    The ventromedial nucleus of the hypothalamus (VMH) is a key cell group in the medial-basal hypothalamus that participates in the regulation of energy balance. Previous studies have shown that the cellular organization of the VMH is altered in mice with a disruption of the steroidogenic factor-1 (NR5a1) gene (SF-1 KO mice). The present study examined orexigenic/anorexigenic peptides (neuropeptide Y (NPY), agouti-related peptide (AgRP) and cocaine- and amphetamine-regulated transcript (CART)) and neural connections to and from the VMH in SF1 KO mice. NeuroVue tracing and Golgi staining were used to evaluate connections between the preoptic area (POA) and VMH and the orientation of dendrites in the VMH, respectively. Results of this study reveal changes in the cytoarchitecture of the region of the VMH with respect to the distribution of immunoreactive NPY, AgRP and CART. In WT mice projections from the POA normally surround the VMH while in SF-1 KO mice, projections from the POA stream through the region that would otherwise be VMH. Golgi impregnation of the region revealed fewer dendrites with ventrolateral orientations and in general, more variable dendritic orientations in SF-1 KO mice providing additional evidence that the connectivity of cells in the region is likely altered due to the cellular rearrangements consequent to disruption of the NR5a1 gene. In conclusion, this study greatly extends the data showing that the morphology of the regions containing the VMH is disrupted in SF-1 KO mice and suggests that changes in the location of cells or fibers containing NPY, AgRP and CART may, in part, account for changes in body weight homeostasis in these mice. PMID:21906594

  8. A role for γS-crystallin in the organization of actin and fiber cell maturation in the mouse lens.

    PubMed

    Fan, Jianguo; Dong, Lijin; Mishra, Sanghamitra; Chen, Yingwei; FitzGerald, Paul; Wistow, Graeme

    2012-08-01

    γS-crystallin (γS) is a highly conserved component of the eye lens. To gain insights into the functional role(s) of this protein, the mouse gene (Crygs) was deleted. Although mutations in γS can cause severe cataracts, loss of function of γS in knockout (KO) mice produced no obvious lens opacity, but was associated with focusing defects. Electron microscopy showed no major differences in lens cell organization, suggesting that the optical defects are primarily cytoplasmic in origin. KO lenses were also grossly normal by light microscopy but showed evidence of incomplete clearance of cellular organelles in maturing fiber cells. Phalloidin labeling showed an unusual distribution of F-actin in a band of mature fiber cells in KO lenses, suggesting a defect in the organization or processing of the actin cytoskeleton. Indeed, in wild-type lenses, γS and F-actin colocalize along the fiber cell plasma membrane. Relative levels of F-actin and G-actin in wild-type and KO lenses were estimated from fluorescent staining profiles and from isolation of actin fractions from whole lenses. Both methods showed a two-fold reduction in the F-actin/G-actin ratio in KO lenses, whereas no difference in tubulin organization was detected. In vitro experiments showed that recombinant mouse γS can directly stabilize F-actin. This suggests that γS may have a functional role related to actin, perhaps in 'shepherding' filaments to maintain the optical properties of the lens cytoplasm and normal fiber cell maturation.

  9. Flax Fiber Hydrophobic Extract Inhibits Human Skin Cells Inflammation and Causes Remodeling of Extracellular Matrix and Wound Closure Activation

    PubMed Central

    Styrczewska, Monika; Kostyn, Anna; Kulma, Anna; Majkowska-Skrobek, Grazyna; Augustyniak, Daria; Prescha, Anna; Czuj, Tadeusz; Szopa, Jan

    2015-01-01

    Inflammation is the basis of many diseases, with chronic wounds amongst them, limiting cell proliferation and tissue regeneration. Our previous preclinical study of flax fiber applied as a wound dressing and analysis of its components impact on the fibroblast transcriptome suggested flax fiber hydrophobic extract use as an anti-inflammatory and wound healing preparation. The extract contains cannabidiol (CBD), phytosterols, and unsaturated fatty acids, showing great promise in wound healing. In in vitro proliferation and wound closure tests the extract activated cell migration and proliferation. The activity of matrix metalloproteinases in skin cells was increased, suggesting activation of extracellular components remodeling. The expression of cytokines was diminished by the extract in a cannabidiol-dependent manner, but β-sitosterol can act synergistically with CBD in inflammation inhibition. Extracellular matrix related genes were also analyzed, considering their importance in further stages of wound healing. The extract activated skin cell matrix remodeling, but the changes were only partially cannabidiol- and β-sitosterol-dependent. The possible role of fatty acids also present in the extract is suggested. The study shows the hydrophobic flax fiber components as wound healing activators, with anti-inflammatory cannabidiol acting in synergy with sterols, and migration and proliferation promoting agents, some of which still require experimental identification. PMID:26347154

  10. Flax Fiber Hydrophobic Extract Inhibits Human Skin Cells Inflammation and Causes Remodeling of Extracellular Matrix and Wound Closure Activation.

    PubMed

    Styrczewska, Monika; Kostyn, Anna; Kulma, Anna; Majkowska-Skrobek, Grazyna; Augustyniak, Daria; Prescha, Anna; Czuj, Tadeusz; Szopa, Jan

    2015-01-01

    Inflammation is the basis of many diseases, with chronic wounds amongst them, limiting cell proliferation and tissue regeneration. Our previous preclinical study of flax fiber applied as a wound dressing and analysis of its components impact on the fibroblast transcriptome suggested flax fiber hydrophobic extract use as an anti-inflammatory and wound healing preparation. The extract contains cannabidiol (CBD), phytosterols, and unsaturated fatty acids, showing great promise in wound healing. In in vitro proliferation and wound closure tests the extract activated cell migration and proliferation. The activity of matrix metalloproteinases in skin cells was increased, suggesting activation of extracellular components remodeling. The expression of cytokines was diminished by the extract in a cannabidiol-dependent manner, but β-sitosterol can act synergistically with CBD in inflammation inhibition. Extracellular matrix related genes were also analyzed, considering their importance in further stages of wound healing. The extract activated skin cell matrix remodeling, but the changes were only partially cannabidiol- and β-sitosterol-dependent. The possible role of fatty acids also present in the extract is suggested. The study shows the hydrophobic flax fiber components as wound healing activators, with anti-inflammatory cannabidiol acting in synergy with sterols, and migration and proliferation promoting agents, some of which still require experimental identification.

  11. Comparison of adenovirus fiber, protein IX, and hexon capsomeres as scaffolds for vector purification and cell targeting

    SciTech Connect

    Campos, Samuel K.; Barry, Michael A. . E-mail: mab@bcm.edu

    2006-06-05

    The direct genetic modification of adenoviral capsid proteins with new ligands is an attractive means to confer targeted tropism to adenoviral vectors. Although several capsid proteins have been reported to tolerate the genetic fusion of foreign peptides and proteins, direct comparison of cell targeting efficiencies through the different capsomeres has been lacking. Likewise, direct comparison of with one or multiple ligands has not been performed due to a lack of capsid-compatible ligands available for retargeting. Here we utilize a panel of metabolically biotinylated Ad vectors to directly compare targeted transduction through the fiber, protein IX, and hexon capsomeres using a variety of biotinylated ligands including antibodies, transferrin, EGF, and cholera toxin B. These results clearly demonstrate that cell targeting with a variety of high affinity receptor-binding ligands is only effective when transduction is redirected through the fiber protein. In contrast, protein IX and hexon-mediated targeting by the same set of ligands failed to mediate robust vector targeting, perhaps due to aberrant trafficking at the cell surface or inside targeted cells. These data suggest that vector targeting by genetic incorporation of high affinity ligands will likely be most efficient through modification of the adenovirus fiber rather than the protein IX and hexon capsomeres. In contrast, single-step monomeric avidin affinity purification of Ad vectors using the metabolic biotinylation system is most effective through capsomeres like protein IX and hexon.

  12. Composite pullulan-dextran polysaccharide scaffold with interfacial polyelectrolyte complexation fibers: a platform with enhanced cell interaction and spatial distribution.

    PubMed

    Cutiongco, Marie Francene Arnobit; Tan, Ming Hao; Ng, Martin Yoke Kuang; Le Visage, Catherine; Yim, Evelyn King Fai

    2014-10-01

    Hydrogels are highly preferred in soft tissue engineering because they recapitulate the hydrated extracellular matrix. Naturally derived polysaccharides, like pullulan and dextran, are attractive materials with which to form hydrophilic polymeric networks due to their non-immunogenic and non-antigenic properties. However, their inherent hydrophilicity prevents adherent cell growth. In this study, we modified pullulan-dextran scaffolds with interfacial polyelectrolyte complexation (IPC) fibers to improve their ability to support adherent cell growth. We showed that the pullulan-dextran-IPC fiber composite scaffold laden with extracellular matrix protein has improved cell adhesion and proliferation compared to the plain polysaccharide scaffold. We also demonstrated the zero-order release kinetics of the biologics bovine serum albumin and vascular endothelial growth factor (VEGF) incorporated in the composite scaffold. Lastly, we showed that the VEGF released from the composite scaffold retained its capacity to stimulate endothelial cell growth. The incorporation of IPC fibers in the pullulan-dextran hydrogel scaffold improved its functionality and biological activity, thus enhancing its potential in tissue engineering applications.

  13. In vitro performance of 13-93 bioactive glass fiber and trabecular scaffolds with MLO-A5 osteogenic cells.

    PubMed

    Modglin, Vernon C; Brown, Roger F; Fu, Qiang; Rahaman, Mohamed N; Jung, Steven B; Day, Delbert E

    2012-10-01

    This in vitro study was performed to evaluate the ability of two types of porous bioactive glass scaffolds to support the growth and differentiation of an established osteogenic cell line. The two scaffold types tested included 13-93 glass fiber and trabecular-like scaffolds seeded with murine MLO-A5 cells and cultured for intervals of 2 to 12 days. Culture in MTT-containing medium showed metabolically active cells both on the surface and within the interior of the scaffolds. Scanning electron microscopy revealed well-attached cells on both types of scaffolds with a continual increase in cell density over a 6-day period. Protein measurements also showed a linear increase in cell density during the incubation. Activity of alkaline phosphatase, a key indicator of osteoblast differentiation, increased about 10-fold during the 6-day incubation with both scaffold types. The addition of mineralization media to MLO-A5 seeded scaffolds triggered extensive formation of alizarin red-positive mineralized extracellular material, additional evidence of cell differentiation and completion of the final step of bone formation on the constructs. Collectively, the results indicate that the 13-93 glass fiber and trabecular scaffolds promote the attachment, growth, and differentiation of MLO-A5 osteogenic cells and could potentially be used for bone tissue engineering applications.

  14. Dual targeting of gene delivery by genetic modification of adenovirus serotype 5 fibers and cell-selective transcriptional control.

    PubMed

    Work, L M; Ritchie, N; Nicklin, S A; Reynolds, P N; Baker, A H

    2004-08-01

    Adenovirus (Ad)-mediated gene delivery is a promising approach for genetic manipulation of the vasculature and is being used in both preclinical models and clinical trials. However, safety concerns relating to infection of nontarget tissue and the poor infectivity of vascular cells compared to other cell types necessitates Ad vector refinement. Here, we combine a transductional targeting approach to improve vascular cell infectivity through RGD peptide insertion into adenovirus fibers, combined with transcriptional targeting to endothelial cells using a approximately 1 kb fragment of the fms-like tyrosine kinase receptor-1 (FLT-1) promoter. Single- and double-modified vectors were characterized in human cell lines that either support or have silenced FLT-1 expression. In rat hepatocytes and endothelial cells, the double modification substantially shifted transduction profiles toward vascular endothelial cells. Furthermore, in intact aortae derived from spontaneously hypertensive rats that display enhanced alphav integrin expression on dysfunctional endothelium, enhanced levels of transduction were observed using the double-modified vector but not in aortae derived from normotensive control rats. Our data indicate that Ad-mediated transduction can be beneficially modified in vitro and in vivo by combining fiber modification and a cell-selective promoter within a single-component vector system.

  15. The Effect of Electrospun Gelatin Fibers Alignment on Schwann Cell and Axon Behavior and Organization in the Perspective of Artificial Nerve Design

    PubMed Central

    Gnavi, Sara; Fornasari, Benedetta Elena; Tonda-Turo, Chiara; Laurano, Rossella; Zanetti, Marco; Ciardelli, Gianluca; Geuna, Stefano

    2015-01-01

    Electrospun fibrous substrates mimicking extracellular matrices can be prepared by electrospinning, yielding aligned fibrous matrices as internal fillers to manufacture artificial nerves. Gelatin aligned nano-fibers were prepared by electrospinning after tuning the collector rotation speed. The effect of alignment on cell adhesion and proliferation was tested in vitro using primary cultures, the Schwann cell line, RT4-D6P2T, and the sensory neuron-like cell line, 50B11. Cell adhesion and proliferation were assessed by quantifying at several time-points. Aligned nano-fibers reduced adhesion and proliferation rate compared with random fibers. Schwann cell morphology and organization were investigated by immunostaining of the cytoskeleton. Cells were elongated with their longitudinal body parallel to the aligned fibers. B5011 neuron-like cells were aligned and had parallel axon growth when cultured on the aligned gelatin fibers. The data show that the alignment of electrospun gelatin fibers can modulate Schwann cells and axon organization in vitro, suggesting that this substrate shows promise as an internal filler for the design of artificial nerves for peripheral nerve reconstruction. PMID:26062130

  16. Hydrodynamically stable adhesion of endothelial cells onto a polypropylene hollow fiber membrane by modification with adhesive protein.

    PubMed

    Takagi, Mutsumi; Shiwaku, Kouji; Inoue, Takeomi; Shirakawa, Yukitoshi; Sawa, Yoshiki; Matsuda, Hikaru; Yoshida, Toshiomi

    2003-01-01

    The effect on the adhesion of endothelial cells of immobilization of adhesion proteins onto a microporous polypropylene hollow fiber membrane for a conventional artificial lung was investigated with the aim of constructing a hybrid artificial lung bearing endothelial cells on the modified membrane. The membrane was modified by adsorption or covalent bonding of adhesion proteins of fibronectin, gelatin, or Pronectin. The density of adherent cells on the membrane modified by adsorption of or covalent bonding with fibronectin reached 1 x 10(5) cells/cm(2) after 1 day of incubation, which corresponds to the confluent cell density in a conventional culture dish, while the cell densities on the membranes modifieds with gelatin and Pronectin were 1-5 x 10(4) cells/cm(2) and 0.5-1 x 10(4) cells/cm(2), respectively. The loading of hydrodynamic shear force (0.23 N/m(2)) for 30 min to the membranes bearing endothelial cells had little effect on the density of adhered cells. The membrane covalently bonded with fibronectin could well maintain a high cell density even after the loading of a higher shear force of 1.15 N/m(2) for 180 min, however, at this level of shear force 49% of adhered cells on the fibronectin-adsorbed membrane were lost after 30 min. A partial cardiopulmonary bypass in rats employing the hybrid artificial lung model composed of a polypropylene hollow fiber membrane covalently bonded with fibronectin and endothelial cell adhesion showed the inhibition of tumor necrosis factor-Alpha release and an increase in IL-10 concentration in the circulating blood compared with that employing an artificial lung without cells. Long-term partial cardiopulmonary bypass employing the hybrid artificial lung model should be studied further.

  17. A change in the pattern of activity affects the developmental regression of the Purkinje cell polyinnervation by climbing fibers in the rat cerebellum.

    PubMed

    Andjus, P R; Zhu, L; Cesa, R; Carulli, D; Strata, P

    2003-01-01

    Pattern of activity during development is important for the refinement of the final architecture of the brain. In the cerebellar cortex, the regression from multiple to single climbing fiber innervation of the Purkinje cell occurs during development between postnatal days (P) 5 and 15. However, the regression is hampered by altering in various ways the morpho-functional integrity of the parallel fiber input. In rats we disrupted the normal activity pattern of the climbing fiber, the terminal arbor of the inferior olive neurons, by administering harmaline for 4 days from P9 to P12. At all studied ages (P15-87) after harmaline treatment multiple (double only) climbing fiber EPSC-steps persist in 28% of cells as compared with none in the control. The ratio between the amplitudes of the larger and the smaller climbing fiber-evoked EPSC increases in parallel with the decline of the polyinnervation factor, indicating a gradual enlargement of the synaptic contribution of the winning climbing fiber synapse at the expense of the losing one. Harmaline treatment had no later effects on the climbing fiber EPSC kinetics and I/V relation in Purkinje cells (P15-36). However, there was a rise in the paired-pulse depression indicating a potentiation of the presynaptic mechanisms. In the same period, after harmaline treatment, parallel fiber-Purkinje cell electrophysiology was unaffected. The distribution of parallel fiber synaptic boutons was also not changed. Thus, a change in the pattern of activity during a narrow developmental period may affect climbing fiber-Purkinje cell synapse competition resulting in occurrence of multiple innervation at least up to 3 months of age. Our results extend the current view on the role of the pattern of activity in the refinement of neuronal connections during development. They suggest that many similar results obtained by different gene or receptor manipulations might be simply the consequence of disrupting the pattern of activity.

  18. Lens fiber cell elongation and differentiation is associated with a robust increase in myosin light chain phosphorylation in the developing mouse.

    PubMed

    Maddala, Rupalatha; Skiba, Nikolai; Vasantha Rao, Ponugoti

    2007-10-01

    Myosin II, a molecular motor, plays a critical role in cell migration, cell shape changes, cell adhesion, and cytokinesis. To understand the role of myosin II in lens fiber cell elongation and differentiation, we determined the distribution pattern of nonmuscle myosin IIA, IIB, and phosphorylated regulatory myosin light chain-2 (phospho-MLC) in frozen sections of the developing mouse lens by immunofluorescence analysis. While myosin IIA was distributed uniformly throughout the differentiating lens, including the epithelium and fibers, myosin IIB was localized predominantly to the epithelium and the posterior tips of the lens fibers. In contrast, immunostaining with a di-phospho-MLC antibody localized intensely and precisely to the elongating and differentiating primary and secondary lens fibers, co-localizing with actin filaments. An in situ analysis of Rho GTPase activation revealed that Rho-GTP was distributed uniformly throughout the embryonic lens, including epithelium and fibers. Inhibition of myosin light chain kinase (MLCK) activity by ML-7 in organ cultured mouse lenses led to development of nuclear lens opacity in association with abnormal fiber cell organization. Taken together, these data reveal a distinct spatial distribution pattern of myosin II isoforms in the developing lens and a robust activation of MLC phosphorylation in the differentiating lens fibers. Moreover, the regulation of MLC phosphorylation by MLCK appears to be critical for crystallin organization and for maintenance of lens transparency and lens membrane function.

  19. Improving cytoactive of endothelial cell by introducing fibronectin to the surface of poly L-Lactic acid fiber mats via dopamine.

    PubMed

    Yang, Wufeng; Zhang, Xiazhi; Wu, Keke; Liu, Xiaoyan; Jiao, Yanpeng; Zhou, Changren

    2016-12-01

    A simple but straightforward approach was reported to prepare fiber mats modified with fibronectin (Fn) protein for endothelial cells activity study. Based on the self-polymerization and strong adhesion feature of dopamine, poly L-Lactic acid (PLLA) fibers mat was modified via simply immersing them into dopamine solution for 16h. Subsequently, Fn was immobilized onto the fiber mats surface by the coupling reactive polydopamine (PDA) layer and Fn. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to determine the chemical compositions of fiber mats surface, which confirmed the successful immobilization of PDA and Fn molecules on the fiber surface. Scanning electronic microscopy (SEM) was used to observe the surface morphology changes after modification with PDA and Fn. The data of water contact angle showed that the hydrophilicity of the fiber mats was improved after surface modification. The data of in vitro cell culture proved that the PDA and Fn modified surface significantly enhanced the adhesion, proliferation and cell activity of endothelial cells on the fiber mats. And the release of tumor necrosis factor-α (TNF-α) by endothelial cells on the modified surface was suppressed compared to that on culture plate and PLLA film at 2 and 4days, while the secretion of interleukin-1β (IL-1β) was increased compared to that on culture plate and PLLA film at 2days.

  20. Functionalization of electrospun fibers of poly(epsilon-caprolactone) with star shaped NCO-poly(ethylene glycol)-stat-poly(propylene glycol) for neuronal cell guidance.

    PubMed

    Klinkhammer, Kristina; Bockelmann, Julia; Simitzis, Chariklia; Brook, Gary A; Grafahrend, Dirk; Groll, Jürgen; Möller, Martin; Mey, Jörg; Klee, Doris

    2010-09-01

    Microfibers produced with electrospinning have recently been used in tissue engineering. In the development of artificial implants for nerve regeneration they are of particular interest as guidance structures for cell migration and axonal growth. Using electrospinning we produced parallel-orientated biocompatible fibers in the submicron range consisting of poly(epsilon-caprolactone) (PCL) and star shaped NCO-poly(ethylene glycol)-stat-poly(propylene glycol) (sPEG). Addition of the bioactive peptide sequence glycine-arginine-glycine-aspartate-serine (GRGDS) or the extracellular matrix protein fibronectin to the electrospinning solution resulted in functionalized fibers. Surface characteristics and biological properties of functionalized and non-functionalised fibers were investigated. Polymer solutions and electrospinning process parameters were varied to obtain high quality orientated fibers. A polymer mixture containing high molecular weight PCL, PCL-diol, and sPEG permitted a chemical reaction between hydroxyl groups of the diol and isocyanante groups of the sPEG. Surface analysis demonstrated that sPEG at the fiber surface minimized protein adhesion. In vitro experiments using dorsal root ganglia explants showed that the cell repellent property of pure PCL/sPEG fibers was overcome by functionalization either with GRGDS peptide or fibronectin. In this way cell migration and axonal outgrowth along fibers were significantly increased. Thus, functionalized electrospun PCL/sPEG fibers, while preventing non-specific protein adsorption, are a suitable substrate for biological and medical applications.

  1. Laser Frequency Stabilization for Coherent Lidar Applications using Novel All-Fiber Gas Reference Cell Fabrication Technique

    NASA Technical Reports Server (NTRS)

    Meras, Patrick, Jr.; Poberezhskiy, Ilya Y.; Chang, Daniel H.; Levin, Jason; Spiers, Gary D.

    2008-01-01

    Compact hollow-core photonic crystal fiber (HC-PCF)gas frequency reference cell was constructed using a novel packaging technique that relies on torch-sealing a quartz filling tube connected to a mechanical splice between regular and hollow-core fibers. The use of this gas cell for laser frequency stabilization was demonstrated by locking a tunable diode laser to the center of the P9 line from the (nu)1+(nu)3 band of acetylene with RMS frequency error of 2.06 MHz over 2 hours. This effort was performed in support of a task to miniaturize the laser frequency stabilization subsystem of JPL/LMCT Laser Absorption Spectrometer (LAS) instrument.

  2. Adenovirus Type 5 Viral Particles Pseudotyped with Mutagenized Fiber Proteins Show Diminished Infectivity of Coxsackie B-Adenovirus Receptor-Bearing Cells

    PubMed Central

    Jakubczak, John L.; Rollence, Michele L.; Stewart, David A.; Jafari, Jonathon D.; Von Seggern, Dan J.; Nemerow, Glen R.; Stevenson, Susan C.; Hallenbeck, Paul L.

    2001-01-01

    A major limitation of adenovirus type 5 (Ad5)-based gene therapy, the inability to target therapeutic genes to selected cell types, is attributable to the natural tropism of the virus for the widely expressed coxsackievirus-adenovirus receptor (CAR) protein. Modifications of the Ad5 fiber knob domain have been shown to alter the tropism of the virus. We have developed a novel system to rapidly evaluate the function of modified fiber proteins in their most relevant context, the adenoviral capsid. This transient transfection/infection system combines transfection of cells with plasmids that express high levels of the modified fiber protein and infection with Ad5.βgal.ΔF, an E1-, E3-, and fiber-deleted adenoviral vector encoding β-galactosidase. We have used this system to test the adenoviral transduction efficiency mediated by a panel of fiber protein mutants that were proposed to influence CAR interaction. A series of amino acid modifications were incorporated via mutagenesis into the fiber expression plasmid, and the resulting fiber proteins were subsequently incorporated onto adenoviral particles. Mutations located in the fiber knob AB and CD loops demonstrated the greatest reduction in fiber-mediated gene transfer in HeLa cells. We also observed effects on transduction efficiency with mutations in the FG loop, indicating that the binding site may extend to the adjacent monomer in the fiber trimer and in the HI loop. These studies support the concept that modification of the fiber knob domain to diminish or ablate CAR interaction should result in a detargeted adenoviral vector that can be combined simultaneously with novel ligands for the development of a systemically administered, targeted adenoviral vector. PMID:11222722

  3. Olfactory Ensheathing Cells Rescue Optic Nerve Fibers in a Rat Glaucoma Model

    PubMed Central

    Dai, Chao; Khaw, Peng T.; Yin, Zheng Qin; Li, Daqing; Raisman, Geoffrey; Li, Ying

    2012-01-01

    Purpose: To determine if transplantation of olfactory ensheathing cells (OECs) can reduce loss of optic nerve axons after raised intraocular pressure (IOP) in the rat. Methods: OECs cultured from the adult olfactory mucosa were transplanted into the region of the optic disc. The IOP was raised by injection of magnetic microspheres into the anterior chamber. Results: At 4 weeks after raising the IOP, the transplanted OECs had migrated into the dorsal area of the optic nerve head (ONH) where they surrounded the optic nerve fibers with a non-myelinated ensheathment. The mean amount of damage to the ONH astrocytic area in rats was 51.0% compared with 85.8% in those without OEC transplants (P < 0.02) and the mean loss of axons in the optic nerve was 51.0% compared with 80.3% in the absence of OECs (P < 0.01). Conclusions: OECs transplanted into the region of the ONH of the rat can reduce the loss of axons and the damage to ONH astrocytes caused by raised IOP. Translational Relevance: Confirmation of these preliminary experimental data, further understanding of possible mechanisms of axonal protection by OECs, and the longer-term time course of protection could provide a basis for future human clinical trials of autografted OECs, which would be available from autologous nasal epithelial biopsies. PMID:24049703

  4. Improved performance of microbial fuel cell using combination biocathode of graphite fiber brush and graphite granules

    NASA Astrophysics Data System (ADS)

    Zhang, Guo-dong; Zhao, Qing-liang; Jiao, Yan; Zhang, Jin-na; Jiang, Jun-qiu; Ren, Nanqi; Kim, Byung Hong

    2011-08-01

    The efficiency and sustainability of microbial fuel cell (MFC) are heavily dependent on the cathode performance. We show here that the use of graphite fiber brush (GBF) together with graphite granules (GGs) as a basal material for biocathode (MFC reactor type R1) significantly improve the performance of a MFC compared with MFCs using GGs (MFC reactor type R2) or GFB (MFC reactor type R3) individually. Compared with R3, the use of the combination biocathode (R1) can shorten the start-up time by 53.75%, improve coulombic efficiencies (CEs) by 21.0 ± 2.7% at external resistance (REX) of 500 Ω, and increase maximum power densities by 38.2 ± 12.6%. Though the start-up time and open circuit voltage (OCV) of the reactor R2 are similar to R1, the CE (REX = 500 Ω) and maximum power density of R2 are 21.4 ± 1.7% and 38.2 ± 15.6% lower than that of R1. Fluorescence in situ hybridization (FISH) analyses indicate the bacteria on cathodes of R1 and R2 are richer than that of R3. Molecular taxonomic analyses reveal that the biofilm formed on the biocathode surface is dominated by strains belonging to Nitrobacter, Achromobacter, Acinetobacter, and Bacteroidetes. Combination of GFB and GGs as biocathode material in MFC is more efficient and can achieve sustainable electricity recovery from organic substances, which substantially increases the viability and sustainability of MFCs.

  5. Glass fiber entrapped sorbent for reformates desulfurization for logistic PEM fuel cell power systems

    NASA Astrophysics Data System (ADS)

    Yang, HongYun; Lu, Yong; Tatarchuk, Bruce J.

    Glass fiber entrapped ZnO/SiO 2 sorbent (GFES) was developed to remove sulfur species (mainly hydrogen sulfide, H 2S) from reformates for logistic PEM fuel cell power systems. Due to the use of microfibrous media and nanosized ZnO grains on highly porous SiO 2 support, GFES demonstrated excellent desulfurization performance and potential to miniaturize the desulfurization reactors. In the thin bed test, GFES (2.5 mm bed thickness) attained a breakthrough time of 540 min with up to 75% ZnO utilization at 1 ppm breakthrough. At equivalent ZnO loading, GFES yielded a breakthrough time twice as long as the ZnO/SiO 2 sorbent; at equivalent bed volume, GFES provided a three times longer breakthrough time (with 67% reduction in ZnO loading) than packed beds of 1-2 mm commercial extrudates. GFES is highly regenerable compared with the commercial extrudates, and can easily be regenerated in situ in air at 500 °C. During 50 regeneration/desulfurization cycles, GFES maintained its desulfurization performance and structural integrity. A composite bed consisting of a packed bed of large extrudates followed by a polishing layer of GFES demonstrated a great extension in gas life and overall bed utilization. This approach synergistically combines the high volume loading of packed beds with the overall contacting efficiency of small particulates.

  6. Olfactory Ensheathing Cells Rescue Optic Nerve Fibers in a Rat Glaucoma Model.

    PubMed

    Dai, Chao; Khaw, Peng T; Yin, Zheng Qin; Li, Daqing; Raisman, Geoffrey; Li, Ying

    2012-01-01

    To determine if transplantation of olfactory ensheathing cells (OECs) can reduce loss of optic nerve axons after raised intraocular pressure (IOP) in the rat. OECs cultured from the adult olfactory mucosa were transplanted into the region of the optic disc. The IOP was raised by injection of magnetic microspheres into the anterior chamber. At 4 weeks after raising the IOP, the transplanted OECs had migrated into the dorsal area of the optic nerve head (ONH) where they surrounded the optic nerve fibers with a non-myelinated ensheathment. The mean amount of damage to the ONH astrocytic area in rats was 51.0% compared with 85.8% in those without OEC transplants (P < 0.02) and the mean loss of axons in the optic nerve was 51.0% compared with 80.3% in the absence of OECs (P < 0.01). OECs transplanted into the region of the ONH of the rat can reduce the loss of axons and the damage to ONH astrocytes caused by raised IOP. Confirmation of these preliminary experimental data, further understanding of possible mechanisms of axonal protection by OECs, and the longer-term time course of protection could provide a basis for future human clinical trials of autografted OECs, which would be available from autologous nasal epithelial biopsies.

  7. Hydrogen production in single chamber microbial electrolysis cells with stainless steel fiber felt cathodes

    NASA Astrophysics Data System (ADS)

    Su, Min; Wei, Liling; Qiu, Zhaozheng; Wang, Gang; Shen, Jianquan

    2016-01-01

    Microbial electrolysis cell (MEC) is a promising technology for sustainable production of hydrogen from biodegradable carbon sources. Employing a low-cost and high efficient cathode to replace platinum catalyzed cathode (Pt/C) for hydrogen generation is a challenge for commercialization of MEC. Here we show that a 3D macroporous stainless steel fiber felt (SSFF) with high electrochemical active surface area has an excellent catalytic activity for hydrogen generation, which is comparable to Pt/C cathode and superior to stainless steel mesh (SSM) cathode in the single-chamber MEC. The SSFF cathode (mean filter rating 100 μm) produces hydrogen at a rate of 3.66 ± 0.43 m3 H2 m-3d-1 (current density of 17.29 ± 1.68 A m-2), with a hydrogen recovery of 76.37 ± 15.04% and overall energy efficiency of 79.61 ± 13.07% at an applied voltage of 0.9 V. The performance of SSFF cathode improves over time due to a decrease in overpotential which caused by corrosion. These results demonstrate that SSFF can be a promising alternative for Pt catalytic cathode in MEC for hydrogen production.

  8. Development of fine-celled bio-fiber composite foams using physical blowing agents and nano-particles

    NASA Astrophysics Data System (ADS)

    Guo, Gangjian

    As one of eco-friendly bio-fibers, wood-fiber has been incorporated in plastics to make wood-fiber/plastic composites (WPC) with an increased stiffness, durability and lowered cost. However, these improvements are usually accompanied by loss in the ductility and impact strength of the composites. These shortcomings can be significantly improved by incorporating a fine-cell foam structure in the composites. This thesis presents the development of the foaming technology for the manufacture of fine-cell WPC foams with environmentally benign physical blowing agents (PBAs), and focuses on the elucidation of the fundamental foaming mechanisms and the related issues involved. One critical issue comes from the volatiles evolved from the wood-fiber during high temperature processing. The volatiles, as a blowing agent, can contribute to the foaming process. However, they lead to gross deterioration of the cell structure of WPC foams. The presence of volatiles makes foaming of WPC "a poorly understood black art". With the use of PBAs, a strategy of lowering processing temperature becomes feasible, to suppress the generation of volatiles. A series of PBA-based experiments were designed using a statistical design of experiments (DOE) technique, and were performed to establish the relationship of processing and material variables with the structure of WPC foams. Fundamental foaming behaviors for two different PBAs and two different polymer systems were identified. WPC foams with a fine-cell morphology and a desired density were successfully obtained at the optimized conditions. Another limitation for the wider application of WPC is their flammability. Innovative use of a small amount of nano-clay in WPC significantly improved the flame-retarding property of WPC, and the key issue was to achieve a high degree of exfoliation of nano-particles in the polymer matrix, to achieve a desired flammability reduction. The synergistic effects of nano-particles in foaming of WPC were

  9. Intron-mediated alternative splicing of WOOD-ASSOCIATED NAC TRANSCRIPTION FACTOR1B regulates cell wall thickening during fiber development in Populus species.

    PubMed

    Zhao, Yunjun; Sun, Jiayan; Xu, Peng; Zhang, Rui; Li, Laigeng

    2014-02-01

    Alternative splicing is an important mechanism involved in regulating the development of multicellular organisms. Although many genes in plants undergo alternative splicing, little is understood of its significance in regulating plant growth and development. In this study, alternative splicing of black cottonwood (Populus trichocarpa) wood-associated NAC domain transcription factor (PtrWNDs), PtrWND1B, is shown to occur exclusively in secondary xylem fiber cells. PtrWND1B is expressed with a normal short-transcript PtrWND1B-s as well as its alternative long-transcript PtrWND1B-l. The intron 2 structure of the PtrWND1B gene was identified as a critical sequence that causes PtrWND1B alternative splicing. Suppression of PtrWND1B expression specifically inhibited fiber cell wall thickening. The two PtrWND1B isoforms play antagonistic roles in regulating cell wall thickening during fiber cell differentiation in Populus spp. PtrWND1B-s overexpression enhanced fiber cell wall thickening, while overexpression of PtrWND1B-l repressed fiber cell wall thickening. Alternative splicing may enable more specific regulation of processes such as fiber cell wall thickening during wood formation.

  10. Small intestinal goblet cell proliferation induced by ingestion of soluble and insoluble dietary fiber is characterized by an increase in sialylated mucins in rats.

    PubMed

    Hino, Shingo; Takemura, Naoki; Sonoyama, Kei; Morita, Akio; Kawagishi, Hirokazu; Aoe, Seiichiro; Morita, Tatsuya

    2012-08-01

    The study aimed to examine the effects of insoluble and soluble fibers on mucin sialylation and sulfation in the small intestine. First, diets containing soluble [konjac mannan (KM), psyllium, or guar gum; 50 g/kg) or insoluble (polystyrene foam, wheat bran, or cornhusk; 80 g/kg) fiber were fed to rats for 13 d. The fiber-fed groups had more goblet cells in the ileum than the fiber-free control group. High-iron diamine/alcian blue staining showed more sialylated mucin-producing cells in the fiber-fed groups than in the control, whereas sulfated mucin-producing cells were fewer (insoluble fibers) or unchanged (soluble fibers). Second, feeding KM (50 g/kg) and beet fiber (BF) (80 g/kg) diets for 7 d yielded a higher ileum Siat4C expression than the control, but Gal3ST2 and Gal3ST4 expression was comparable. Luminal mucin content correlated with sialic acid (r = 0.96; P < 0.001) or sulfate (r = 0.62; P < 0.01), but the slope of the sialic acid-derived equation was greater than that of the sulfate-derived equation, indicating a preferred increase in sialylated mucins. Third, rats were fed the control diet for 10 d while receiving antibiotic treatment. Analysis of the luminal mucin showed that sialylated mucins were more vulnerable to bacterial degradation than sulfated mucins. Finally, a study of bromo-deoxyuridine incorporation in rats fed a BF diet indicated that goblet cell proliferation accompanied by increased sialylated mucin appeared to be related to accelerated ileal epithelial cell migration. We conclude that intestinal goblet cell responses to insoluble and soluble fibers are characterized by increases in sialylated mucin production.

  11. Nerve fiber layer thinning lags retinal ganglion cell density following crush axonopathy.

    PubMed

    Munguba, Gustavo C; Galeb, Sanja; Liu, Yuan; Landy, David C; Lam, Daisy; Camp, Andrew; Samad, Sinthia; Tapia, Mary L; Lee, Richard K

    2014-09-16

    We investigated the progressive nature of neurodegenerative structural changes following injury to retinal ganglion cell (RGC) axons using quantifiable and noninvasive in vivo imaging techniques. To track degenerative RGC progression in retinas following optic nerve crush (ONC) injury, spectral-domain optical coherence tomography (SD-OCT) was used to quantitate the RGC nerve fiber layer (NFL) density. The RGC soma cell density (RCD) was measured by confocal scanning laser ophthalmoscopy (CSLO). The RCD counts were performed using blood vessels as landmarks to anatomically track defined progressive changes in enhanced yellow fluorescent fusion protein (EYFP)-labeled RGCs. Following ONC injury, 68% of the observed decrease in RCD measured by CSLO and 54% of the NFL thickness obtained by SD-OCT imaging (N=4 retinas) occurred within the first week. Between days 7 and 14, an additional 22% decrease in RCD was concurrent with a 31% decrease in overall NFL thickness. Finally, between days 14 and 21, an additional 10% decrease in RCD measured in vivo by CSLO and 15% decrease in NFL thickness by SD-OCT was observed. Our data suggest that in vivo CSLO imaging of EYFP-RGC expression and SD-OCT measured NFL thickness are fast and reliable methods that longitudinally track neurodegenerative progression following ONC injury. Neurodegenerative changes in NFL thickness measured by SD-OCT imaging have the same overall trajectory as those observed by CSLO for RCD; however, changes in NFL thickness initially lag behind in vivo RGC soma counts with a slower decline in overall measurable change. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  12. Nerve Fiber Layer Thinning Lags Retinal Ganglion Cell Density Following Crush Axonopathy

    PubMed Central

    Munguba, Gustavo C.; Galeb, Sanja; Liu, Yuan; Landy, David C.; Lam, Daisy; Camp, Andrew; Samad, Sinthia; Tapia, Mary L.; Lee, Richard K.

    2014-01-01

    Purpose. We investigated the progressive nature of neurodegenerative structural changes following injury to retinal ganglion cell (RGC) axons using quantifiable and noninvasive in vivo imaging techniques. Methods. To track degenerative RGC progression in retinas following optic nerve crush (ONC) injury, spectral-domain optical coherence tomography (SD-OCT) was used to quantitate the RGC nerve fiber layer (NFL) density. The RGC soma cell density (RCD) was measured by confocal scanning laser ophthalmoscopy (CSLO). The RCD counts were performed using blood vessels as landmarks to anatomically track defined progressive changes in enhanced yellow fluorescent fusion protein (EYFP)-labeled RGCs. Results. Following ONC injury, 68% of the observed decrease in RCD measured by CSLO and 54% of the NFL thickness obtained by SD-OCT imaging (N = 4 retinas) occurred within the first week. Between days 7 and 14, an additional 22% decrease in RCD was concurrent with a 31% decrease in overall NFL thickness. Finally, between days 14 and 21, an additional 10% decrease in RCD measured in vivo by CSLO and 15% decrease in NFL thickness by SD-OCT was observed. Conclusions. Our data suggest that in vivo CSLO imaging of EYFP-RGC expression and SD-OCT measured NFL thickness are fast and reliable methods that longitudinally track neurodegenerative progression following ONC injury. Neurodegenerative changes in NFL thickness measured by SD-OCT imaging have the same overall trajectory as those observed by CSLO for RCD; however, changes in NFL thickness initially lag behind in vivo RGC soma counts with a slower decline in overall measurable change. PMID:25228542

  13. Storage related changes of cell wall based dietary fiber components of broccoli (Brassica oleracea var. italica) stems.

    PubMed

    Schäfer, Judith; Stanojlovic, Luisa; Trierweiler, Bernhard; Bunzel, Mirko

    2017-03-01

    Storage related changes in the cell wall composition potentially affect the texture of plant-based foods and the physiological effects of cell wall based dietary fiber components. Therefore, a detailed characterization of cell wall polysaccharides and lignins from broccoli stems was performed. Freshly harvested broccoli and broccoli stored at 20°C and 1°C for different periods of time were analyzed. Effects on dietary fiber contents, polysaccharide composition, and on lignin contents/composition were much more pronounced during storage at 20°C than at 1°C. During storage, insoluble dietary fiber contents of broccoli stems increased up to 13%. Storage related polysaccharide modifications include an increase of the portions of cellulose, xylans, and homogalacturonans and a decrease of the neutral pectic side-chains arabinans and galactans. Broccoli stem lignins are generally rich in guaiacyl units. Lignins from freshly harvested broccoli stems contain slightly larger amounts of p-hydroxyphenyl units than syringyl units. Syringyl units are predominantly incorporated into the lignin polymers during storage, resulting in increased acetyl bromide soluble lignin contents. NMR-based analysis of the interunit linkage types of broccoli stem lignins revealed comparably large portions of resinol structures for a guaiacyl rich lignin. Incorporation of syringyl units into the polymers over storage predominantly occurs through β-O-4-linkages.

  14. Osteogenic induction of bone marrow-derived stromal cells on simvastatin-releasing, biodegradable, nano- to microscale fiber scaffolds.

    PubMed

    Wadagaki, Ryu; Mizuno, Daiki; Yamawaki-Ogata, Aika; Satake, Makoto; Kaneko, Hiroaki; Hagiwara, Sumitaka; Yamamoto, Noriyuki; Narita, Yuji; Hibi, Hideharu; Ueda, Minoru

    2011-07-01

    Tissue engineering is an effective approach for the treatment of bone defects. Statins have been demonstrated to promote osteoblastic differentiation of bone marrow-derived stromal cells (BMSCs). Electrospun biodegradable fibers have also shown applicability to drug delivery in the form of bone tissue engineered scaffolds with nano- to microscale topography and high porosity similar to the natural extracellular matrix (ECM). The aim of this study was to investigate the feasibility of a simvastatin-releasing, biodegradable, nano- to microscale fiber scaffold (SRBFS) for bone tissue engineering with BMSCs. Simvastatin was released from SRBFS slowly. BMSCs were observed to spread actively and rigidly adhere to SRBFS. BMSCs on SRBFS showed an increase in alkaline phosphatase activity 2 weeks after cell culture. Furthermore, osteoclastogenesis was suppressed by SRBFS in vitro. The new bone formation and mineralization in the SRBFS group were significantly better than in the biodegradable fiber scaffold (BFS) without simvastatin 12 weeks after implantation of the cell-scaffold construct into an ectopic site on the murine back. These results suggest that SRBFS promoted osteoblastic differentiation of BMSCs in vitro and in vivo, and demonstrate feasibility as a bone engineering scaffold.

  15. Effects of silk fibroin fiber incorporation on mechanical properties, endothelial cell colonization and vascularization of PDLLA scaffolds

    PubMed Central

    Stoppato, M.; Stevens, H. Y.; Carletti, E.; Migliaresi, C.; Motta, A.; Guldberg, R. E.

    2013-01-01

    Attainment of functional vascularization of engineered constructs is one of the fundamental challenges of tissue engineering. However, the development of an extracellular matrix in most tissues, including bone, is dependent upon the establishment of a well developed vascular supply. In this study a poly-D,L-lactic acid (PDLLA) salt-leached sponge was modified by incorporation of silk fibroin fibers to create a multicomponent scaffold, in an effort to better support endothelial cell colonization and to promote in vivo vascularization. Scaffolds with and without silk fibroin fibers were compared for microstructure, mechanical properties, ability to maintain cell populations in vitro as well as to permit vascular ingrowth into acellular constructs in vivo. We demonstrated that adding silk fibroin fibers to a PDLLA salt-leached sponge enhanced scaffold properties and heightened its capacity to support endothelial cells in vitro and to promote vascularization in vivo. Therefore refinement of scaffold properties by inclusion of materials with beneficial attributes may promote and shape cellular responses. PMID:23522374

  16. Influence of lactobacilli on the adhesion of Staphylococcus aureus and Candida albicans to fibers and epithelial cells.

    PubMed

    Reid, G; Tieszer, C; Lam, D

    1995-09-01

    The ability of organisms to adhere to and form biofilms on fibrous materials is believed to be an important initiating step in the induction of several diseases, such as toxic shock syndrome. Using an in vitro assay, a moderately hydrophobic strain of Staphylococcus aureus (water contact angle 35 degrees) and a hydrophilic Candida albicans (shown by a hexadecane test) were highly adherent to commercial diaper fibers. The lumen side of the diaper was porous and the fibers were very hydrophobic (> 140 degrees), but the internal section was very hydrophilic (0 degrees), presumably for lus strains was present. Surfaces precoated with lactobacilli inhibited staphylococcal adhesion by 26-97%, and candida by 0-67%. When the lactobacilli were used to challenge adherent pathogens, there was 99% displacement of the S. aureus and up to 91% displacement of C. albicans. Hydrophobic L. acidophilus 76 (54 degrees) and T-13 (80 degrees) were the most effective of five Lactobacillus isolates tested at interference by precoating. The moderately hydrophilic L. casei var rhamnosus GR-1 (33 degrees) was the most effective at displacing the yeast. Experiments with uroepithelial cells also showed that the lactobacilli could significantly interfere with the adhesion of both pathogens to the cells. The results demonstrate the rapidity with which two pathogens adhered to fibers and epithelial cells, and raised the possibility that members of the normal female urogenital flora might interfere with infections caused by these organisms.

  17. Hierarchical structural health monitoring system combining a fiber optic spinal cord network and distributed nerve cell devices

    NASA Astrophysics Data System (ADS)

    Minakuchi, Shu; Tsukamoto, Haruka; Takeda, Nobuo

    2009-03-01

    This study proposes novel hierarchical sensing concept for detecting damages in composite structures. In the hierarchical system, numerous three-dimensionally structured sensor devic